Alhafez, IA ;Ruestes, CJ ; Bringa, EM ; Urbassek, HM ; JOURNAL OF ALLOYS AND COMPOUNDS ,2019 ,803 ,618 -624 .
The plastic response of a high-entropy alloy is explored by means of simulated nanoindentation tests. We compare nanoindentation into the Cantor alloy - an equi-atomic CoCrFeMnNi fcc solid solution - with that into an elemental Ni fcc single crystal. Using molecular dynamics simulation, strong differences in the plastic behavior are identified. While the total length of the dislocation network in the Cantor alloy is higher than in Ni, the size of the plastic zone is considerably restricted. Dislocations are more localized in the Cantor alloy, both during indentation, but also during retraction of the indenter; emission of prismatic loops is absent in the Cantor alloy. Besides dislocation-mediated plasticity, considerable twinning occurs. No amorphization could be observed. These simulation results are in good qualitative agreement with our current knowledge of plasticity in high entropy alloys. (C) 2019 Elsevier B.V. All rights reserved.
Colombo, R ;Benavidez, M ; Fernandez Bidondo, L ; Silvani, V ; Bompadre, J ; Statello, M ; Scorza, M ; Scotti, A ; Godeas, A ; ,2019 ,,-.
The Riachuelo river basin (RRB) is considered one of the most polluted environmentsin the world. Knowledge of arbuscular mycorrhizal fungi (AMF) adapted to this extremely pol-luted environment is important for the establishment of future soil restoration projects. Thiswork aims to make a first list of AMF species present on the RRB. Soil and root samples wererandomly taken in an area of approximately 1500 m2, mycorrhization percentages were eval-uated. AMF species were detected by molecular and morphological techniques. Sixteen AMFmorphological species and 64 molecular species were reported in this work. Dominikia iranica, Funneliformis constrictum, Funneliformis mosseae, Rhizophagus intraradices, Rhizophagus irregularis and Septoglomus viscosum were detected by both techniques while Claroideoglomus sp. was only detected by pyrosequencing. The list of species reported in this work representsthe first description of the RRB AMF community.
Ruggeri, MF ;Lana, NB ; Puliafito, SE ; Altamirano, JC ; EMERGING CONTAMINANTS ,2020 ,6 ,103 -113 .
Global monitoring of Persistent Organic Pollutants (POPs) has allowed the knowledge of levels and distribution around the world as well as the understanding of its transport through the atmosphere. However, there are still some gaps in this regard, especially in some locations, as the case of Great Mendoza, a medium-sized urban area located in the center-west of Argentina. In this work, the WRF/CALMET/CALPUFF modeling system was used to estimate airborne levels of four families of POPs (PCBs, PBDEs, DDTs and HCB) in the study area. The model was validated from measured data obtained from eleven sites using passive air samplers with polyurethane foam disks (PUFs), subsequently analyzed by GC-ECNI/MS. Considering both sets of data, measured and simulated airborne concentrations, five statistical performance metrics were calculated for each family of POP [Mean bias error, (MBE), Fractional Bias (FB), Normalized Mean Square Error (NMSE), Factor of two (Fa2) and Pearson correlation coefficient (r)]. Results exhibited a good agreement between modeled and measured data, showing that WRF/CALMET/CALPUFF modeling system predicts POPs airborne concentrations with reasonable accuracy at a local scale. Model output was used to examine the relative source contribution to ground-level concentrations and to assess the spatial variability of the studied POPs in the study area. Source apportionment showed the prevalence of emissions from open burning of municipal solid waste (ranging from 9% to 90%) on the simulated atmospheric concentrations. HCB presented the lowest mean contribution from this activity (37%) but the highest variability (SD ¼ 20%), followed by PCBs (69 ± 9%), and PBDEs (84 ± 4%). The spatial pattern obtained from simulations exhibited that both, lowest and highest levels predicted by the model, occurred in areas where no samples were taken, suggesting that the real gradient in the POPs air concentrations would be much greater than those reflected by measured data. This work highlights the usefulness of the implementation of an atmospheric dispersion model, not only in the study of air quality and exposure levels but also as a tool for the proper design of monitoring networks, taking into account the time and cost that sampling campaigns take, and the conclusions that are intended to be made from the analysis of the obtained data.
Mammana, SB ;Abraham, EC ; Camargo, AB ; Vazquez, A ; Altamirano, JC ; CHEMISTRY SELECT ,2020 ,5 ,2179 -2184 .
Enzymatic digestion, coupled to surfactant assisted-dispersive liquid-liquid microextraction (ED-SA-DLLME), is proposed as a mild innovative sample preparation methodology to determine polybrominated diphenyl ethers (PBDEs) in human hair samples by gas chromatography. The sodium dodecyl sulfate as a promoting agent in the ED stage also acts as a dispersive agent in DLLME, providing an advantageous synergy between sample preparation stages. Experimental variables of the ED-SA-DLLME were optimized using a multivariate method. The optimal experimental conditions were: proteinase K 0.96 U mL-1, SDS 1% (w/v), 37°C, and 60 min for ED; and 50 L tetrachloroethylene for SA-DLLME. The notable analytical figures of merit showed LOQ in the range of 30-430 pg g-1, relative standard deviations <9%, and recoveries of 90-94%. The PBDEs were found in human hair samples <0.07 ng g-1.
Ramirez, D ;Altamirano, JC ; Camargo, AB ; FOOD CHEMISTRY ,2021 ,337 ,-.
Amongst functional foods, garlic and its by-products stand out given their rich phytochemical profile. A comprehensive analytical approach becomes necessary to fully address garlic preparations health-promoting activities, considering the coexistence of several active ingredients from different chemical families. For this, we developed a multi-phytochemical protocol combining Ultrasound and Dispersive Liquid-Liquid Microextraction, coupled to Liquid Chromatography, for the determination of flavonols, organosulfur compounds, and inulin. Hydrophilic interaction chromatography showed an adequate resolution of flavonols and sugars in a shorter time. The protocol showed a suitable performance and acceptable quantitative yields for garlic powder, cooked garlic, black garlic, and liquid garlic flavouring samples. Additionally, the proposed methodology represented a useful tool to assess how the different garlic products related to functional properties, taking into account the various phytochemical families present in each sample. This is the first time a comprehensive and multi-phytochemical validated analysis of garlic preparations is proposed.
Ruggeri, MF ;Bolaño Ortiz, TR ; Pascual, R ; Allende, D ; Puliafito, E ; Altamirano, JC ; PROCESSES IMPACTS ,2020 ,22 ,1491 -1501 .
This study presents the first local measurements of metals in snow from the Argentine Central Andes. Cu, Pb and Zn were selected as specific tracers of anthropogenic local emission sources in the study area. Snow samples were collected during winter (2014, 2015 and 2016) at two sites with different characteristics: Punta de Vacas and Vallecitos. The samples were analyzed by ICP-MS, and the average concentrations found were 1.4 μg L−1 (Cu), 2.2 μg L−1(Pb) and 14.2 μg L−1 (Zn) in the snow samples from Vallecitos, and 5.3 μg L−1(Cu), 2.6 μg L−1 (Pb) and 24.0 μg L−1 (Zn) in the snow samples from Punta de Vacas. These data and the snowfall amount in each sampling site were statistically analyzed. Results suggested that the levels of metals in the snow are influenced not only by the atmospheric concentrations, but also by the amount of precipitated snow. Additionally, an atmospheric dispersion model, CALPUFF, was applied in the study area to determine the origin of the studied metals and to understand the spatial distribution pattern of the concentrations found. Results showed that the metal atmospheric loads in the study area originated from local sources, especially vehicular traffic and mining. This work represents an important contribution to the knowledge and preservation of the local Andean cryosphere, and it could be used as an input to develop protection policies in the area through the combination of different and complementary tools for the evaluation of air quality.
Kuitunen, M ;Altamirano, JC ; Siegenthaler, Peter ; Taure, TH ; Häkkinena, VA ; Vanninen, PS ; ANALYTICAL METHODS ,2020 ,,-.
A simple derivatization technique was developed for the analysis of seven Schedule 3 chemicals and one Schedule 2 chemical listed in the Chemical Weapons Convention (CWC). Phosgene, phosphorus oxychloride, phosphorus trichloride, phosphorus pentachloride, thionyl chloride, sulfur monochloride and sulfur dichloride (Schedule 3) as well as arsenic trichloride (Schedule 2) were derivatized using 1- propanol in 40% pyridine solution for analysis with gas chromatography-mass spectrometry (GC-MS). Derivatization temperature and concentration of the derivatization solution were optimized for maximum derivatization recovery. The stabilities of the target analytes and their derivatives in different solvents were studied. The derivatization yield showed a linear response within the analyte concentration range of 0.1–2 mM (10–200 mg ml_1) with correlation coefficients >0.99 (r2), except for AsCl3 which did not show a linear response after derivatization. Good reproducibility with relative standard deviations (RSDs) from 3 to 13% was achieved. The derivatization recovery was 66% for phosgene and 67–80% for the P-containing chemicals phosphorus oxychloride, phosphorus trichloride and phosphorus pentachloride. Recommendations to use the method for screening the presence of these chemicals in organic liquid samples are given. The method is used when CWC-related samples are screened at VERIFIN.
Rim, DN ;Cremades, P ; Kaluza, PF ; ,2019 ,65 ,58 -63 .
We present a simple low-cost electronic circuit that is able to show two different dynamical regimens with oscillations of voltages and with constant values of them. This device is designed as a negative feedback three-node network inspired in the genetic repressilator. The circuit's behavior is modeled by a system of differential equations which is studied in several different ways by applying the dynamical system formalism, making numerical simulations and constructing and measuring it experimentally. We find that the most important characteristics of the Hopf bifurcation can be found and controlled. Particularly, a resistor value plays the role of the bifurcation parameter, which can be easily varied experimentally. As a result, this system can be employed to introduce many aspects of a research in a real physical system and it enables us to study one of the most important kinds of bifurcation.
Saiz Lopez, A ;Baidar, S ; Cuevas, CA ; Koening, TK ; Fernandez, RP ; Dix, B ; Kinnison, DE ; Lamarque, JF ; Rodriguez Lloveras, X ; Campos, TL ; Volkamer, R ; GEOPHYSICAL RESEARCH LETTERS ,2015 ,42 ,1 -8 .
We report a new estimation of the injection of iodine into the stratosphere based on novel daytime (solar zenith angle < 45°) aircraft observations in the tropical tropopause layer and a global atmospheric model with the most recent knowledge about iodine photochemistry. The results indicate that significant levels of total reactive iodine (0.25–0.7 parts per trillion by volume), between 2 and 5 times larger than the accepted upper limits, can be injected into the stratosphere via tropical convective outflow. At these iodine levels, modeled iodine catalytic cycles account for up to 30% of the contemporary ozone loss in the tropical lower stratosphere and can exert a stratospheric ozone depletion potential equivalent to, or even larger than, that of very short‐lived bromocarbons. Therefore, we suggest that iodine sources and chemistry need to be considered in assessments of the historical and future evolution of the stratospheric ozone layer.
Prados Roman, C ;Cuevas, CA ; Hay, T ; Fernandez, RP ; Mahajan, AS ; Royer, SJ ; Gali, M ; Simo, R ; Dachs, J ; Grobmann, K ; Kinnison, DE ; Lamarque, JF ; Saiz Lopez, A ; ATMOSPHERIC CHEMISTRY AND PHYSICS ,2015 ,15 ,2215 -2224 .
Naturally emitted from the oceans, iodine compounds efficiently destroy atmospheric ozone and reduce its positive radiative forcing effects in the troposphere. Emissions of inorganic iodine have been experimentally shown to depend on the deposition to the oceans of tropospheric ozone, whose concentrations have significantly increased since 1850 as a result of human activities. A chemistry–climate model is used herein to quantify the current ocean emissions of inorganic iodine and assess the impact that the anthropogenic increase in tropospheric ozone has had on the natural cycle of iodine in the marine environment since pre-industrial times. Our results indicate that the human-driven enhancement of tropospheric ozone has doubled the oceanic inorganic iodine emissions following the reaction of ozone with iodide at the sea surface. The consequent build-up of atmospheric iodine, with maximum enhancements of up to 70% with respect to pre-industrial times in continental pollution outflow regions, has in turn accelerated the ozone chemical loss over the oceans with strong spatial patterns. We suggest that this ocean–atmosphere interaction represents a negative geochemical feedback loop by which current ocean emissions of iodine act as a natural buffer for ozone pollution and its radiative forcing in the global marine environment.
Prados Roman, C ;Cuevas, CA ; Hay, T ; Fernandez, RP ; Mahajan, AS ; Royer, SJ ; Gali, M ; Simo, R ; Dachs, J ; Grobmann, K ; Kinnison, DE ; Lamarque, JF ; Saiz Lopez, A ; ATMOSPHERIC CHEMISTRY AND PHYSICS ,2015 ,15 ,583 -593 .
Emitted mainly by the oceans, iodine is a halogen compound important for atmospheric chemistry due to its high ozone depletion potential and effect on the oxidizing capacity of the atmosphere. Here we present a comprehensive data set of iodine oxide (IO) measurements in the open marine boundary layer (MBL) made during the Malaspina 2010 circumnavigation. Results show IO mixing ratios ranging from 0.4 to 1 pmol mol−1 (30% uncertainty) and, complemented with additional field campaigns, this data set confirms through observations the ubiquitous presence of reactive iodine chemistry in the global marine environment. We use a global model with organic (CH3I, CH2ICl, CH2I2 and CH2IBr) and inorganic (HOI and I2) iodine ocean emissions to investigate the contribution of the different iodine source gases to the budget of IO in the global MBL. In agreement with previous estimates, our results indicate that, globally averaged, the abiotic precursors contribute about 75 % to the IO budget. However, this work reveals a strong geographical pattern in the contribution of organic vs. inorganic precursors to reactive iodine in the global MBL.
Nicely, JM ;Anderson, DC ; Canty, TP ; Salawitch, RJ ; Wolfe, GM ; Apel, EC ; Amold, SR ; Atlas, EL ; Blake, NJ ; Bresch, JF ; Campos, TL ; Dickerson, RR ; Duncan, B ; Emmons, LK ; Eyans, MJ ; Fernandez, RP ; Flemming, J ; Hall, SR ; Hanisco, TF ; JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES ,2016 ,121 ,1 -28 .
Hydroxyl radical (OH) is the main daytime oxidant in the troposphere and determines the atmospheric lifetimes of many compounds. We use aircraft measurements of O3, H2O, NO, and other species from the Convective Transport of Active Species in the Tropics (CONTRAST) field campaign, which occurred in the tropical western Pacific (TWP) during January–February 2014, to constrain a photochemical box model and estimate concentrations of OH throughout the troposphere. We find that tropospheric column OH (OHCOL) inferred from CONTRAST observations is 12 to 40% higher than found in chemical transport models (CTMs), including CAM‐chem‐SD run with 2014 meteorology as well as eight models that participated in POLMIP (2008 meteorology). Part of this discrepancy is due to a clear‐sky sampling bias that affects CONTRAST observations; accounting for this bias and also for a small difference in chemical mechanism results in our empirically based value of OHCOL being 0 to 20% larger than found within global models. While these global models simulate observed O3 reasonably well, they underestimate NOx (NO + NO2) by a factor of 2, resulting in OHCOL ~30% lower than box model simulations constrained by observed NO. Underestimations by CTMs of observed CH3CHO throughout the troposphere and of HCHO in the upper troposphere further contribute to differences between our constrained estimates of OH and those calculated by CTMs. Finally, our calculations do not support the prior suggestion of the existence of a tropospheric OH minimum in the TWP, because during January–February 2014 observed levels of O3 and NO were considerably larger than previously reported values in the TWP.
Wang, S ;Kinnison, D ; Montzka, SA ; Apel, EC ; Hombrook, RS ; Hills, AJ ; Blake, DR ; Barletta, B ; Meinardi, S ; Sweeny, C ; Moore, F ; Long, M ; Saiz Lopez, A ; Fernandez, RP ; Tilmes, S ; Emmons, LK ; Lamarque, JF ; JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES ,2019 ,124 ,-.
Halogenated very short lived substances (VSLS) affect the ozone budget in the atmosphere. Brominated VSLS are naturally emitted from the ocean, and current oceanic emission inventories vary dramatically. We present a new global oceanic emission inventory of Br‐VSLS (bromoform and dibromomethane), considering the physical forcing in the ocean and the atmosphere, as well as the ocean biogeochemistry control. A data‐oriented machine‐learning emulator was developed to couple the air‐sea exchange with the ocean biogeochemistry. The predicted surface seawater concentrations and the surface atmospheric mixing ratios of Br‐VSLS are evaluated with long‐term, global‐scale observations; and the predicted vertical distributions of Br‐VSLS are compared to the global airborne observations in both boreal summer and winter. The global marine emissions of bromoform and dibromomethane are estimated to be 385 and 54 Gg Br per year, respectively. The new oceanic emission inventory of Br‐VSLS is more skillful than the widely used top‐down approaches for representing the seasonal/spatial variations and the annual means of atmospheric concentrations. The new approach improves the model predictability for the coupled Earth system model and can be used as a basis for investigating the past and future ocean emissions and feedbacks under climate change. This model framework can be used to calculate the bidirectional oceanic fluxes for other compounds of interest.
Tiwari, YK ;Guha, T ; Valsala, V ; Sainz Lopez, A ; Cuevas, CA ; Fernandez, RP ; Mahajan, A ; ATMOSPHERIC ENVIRONMENT ,2019 ,,-.
Atmospheric methane (CH4) is considered to be one of the most important greenhouse gases due to its increasing atmospheric concentrations and the fact that it has a warming potential 28 times that of atmospheric carbon dioxide (CO2). Over the Indian sub-continent, fluxes and transport both contribute towards CH4 seasonal variability. Its intra-seasonal variability however is more complex as it is additionally influenced by monsoonal activity during the Asian Summer Monsoon (ASM) period. In this study, the intra-seasonal variability of atmospheric CH4 is examined using ground-based observations at two sites located in the Southern Indian Peninsula, Sinhagad (SNG) and Cape Rama (CRI); and outputs from three different model simulations. Both, the ground based observations and multi-model simulations show that the dominant spectral variability of CH4 is coherent with 20–90 day oscillations in the dynamics of the monsoon (termed hereafter as Intra-Seasonal Oscillations, ISOs). The multi-model analysis revealed that CH4 is heavily influenced by advection due to this intra-seasonal variability. The simulations also display a clear northward propagation of CH4 anomalies over India. The co-evolution of CH4, outgoing long wave radiation (to represent convection) and OH radicals (proxy to CH4 sinks) is presented. The study quantifies CH4 variability at intra-seasonal timescales and also its spatial extent. The results suggest that the effect of ISOs on CH4 needs to be considered along with the corresponding observations for future inverse modeling.
Koeing, TK ;Baidar, S ; Campuzano Jost, P ; Cuevas, CA ; Dix, B ; Fernandez, RP ; Guo, H ; Halle, SR ; Kinnisone, D ; Nault, BA ; Ullmanne, K ; Jimenez, JL ; Saiz Lopez, A ; Volkamer, R ; ,2020 ,117 ,1860 -1866 .
Oceanic emissions of iodine destroy ozone, modify oxidative capacity, and can form new particles in the troposphere. However, the impact of iodine in the stratosphere is highly uncertain due to the lack of previous quantitative measurements. Here, we report quantitative measurements of iodine monoxide radicals and particulate iodine (Iy,part) from aircraft in the stratosphere. These measurements support that 0.77 ± 0.10 parts per trillion by volume (pptv) total inorganic iodine (Iy) is injected to the stratosphere. These high Iy amounts are indicative of active iodine recycling on ice in the upper troposphere (UT), support the upper end of recent Iy estimates (0 to 0.8 pptv) by the World Meteorological Organization, and are incompatible with zero stratospheric iodine injection. Gas-phase iodine (Iy,gas) in the UT (0.67 ± 0.09 pptv) converts to Iy,part sharply near the tropopause. In the stratosphere, IO radicals remain detectable (0.06 ± 0.03 pptv), indicating persistent Iy,part recycling back to Iy,gas as a result of active multiphase chemistry. At the observed levels, iodine is responsible for 32% of the halogen-induced ozone loss (bromine 40%, chlorine 28%), due primarily to previously unconsidered heterogeneous chemistry. Anthropogenic (pollution) ozone has increased iodine emissions since preindustrial times (ca. factor of 3 since 1950) and could be partly responsible for the continued decrease of ozone in the lower stratosphere. Increasing iodine emissions have implications for ozone radiative forcing and possibly new particle formation near the tropopause.
Iglesias Suarez, F ;Badia, A ; Fernandez, RP ; Cuevas, AA ; Kinnison, DE ; Tilmes, S ; Lamarque, JF ; Long, M ; Hossaini, R ; Saiz Lopez, A ; NATURE CLIMATE CHANGE ,2020 ,10 ,147 -154 .
Reactive atmospheric halogens destroy tropospheric ozone (O3), an air pollutant and greenhouse gas. The primary source of natural halogens is emissions from marine phytoplankton and algae, as well as abiotic sources from ocean and tropospheric chemistry, but how their fluxes will change under climate warming, and the resulting impacts on O3, are not well known. Here, we use an Earth system model to estimate that natural halogens deplete approximately 13% of tropospheric O3 in the present-day climate. Despite increased levels of natural halogens through the twenty-first century, this fraction remains stable due to compensation from hemispheric, regional and vertical heterogeneity in tropospheric O3 loss. Notably, this halogen-driven O3 buffering is projected to be greatest over polluted and populated regions, due mainly to iodine chemistry, with important implications for air quality.
Del Carmen Abraham, E ;D'Angelo, JA ; Mammana, SB ; Lascalea, GE ; Altamirano, JC ; ,2019 ,4 ,10856 -10862 .
Fractional distillation was applied to recycle and reuse histological xylol waste. A new sample preparation technique for analyzing liquid samples by transmission FTIR spectroscopy was developed and validated. Pressing time, sample volume, and xylol volatility were the optimized variables to acquire good quality spectra by using the KBr pellet technique. The suitability of this technique for analyzing a volatile sample, xylol, was contrasted against a non‐volatile coal sample. Semi‐quantitative IR‐derived ratios were calculated and used as input variables in principal components analysis (PCA). One‐way analysis of variance (ANOVA) test was applied to determine whether the samples of distillate, xylol waste, and commercial xylol showed significant differences among them. Unlike currently used analytical methodologies based on GC, the proposed methodology based on FTIR‐PCA‐ANOVA provided a simple way to monitor the samples (including xylol waste containing water traces and paraffin) throughout xylol recycling process. The results indicated there were no significant differences (p>0.05) between commercial and recycled xylol, being comparable. KBr pellets were prepared in order to obtain transmission FTIR spectra of liquid samples from xylol recycling process. Semi‐quantitative IR‐data were introduced in PCA analysis, and one‐way ANOVA test showed there were no significant differences between commercial and distilled xylol, which can be reused supporting waste prevention.
Rios, JM ;Ruggeri, MF ; Poma, G ; Malarvannan, G ; Covaci, A ; Puliafito, SE ; Ciocco, NF ; Altamirano, JC ; ,2019 ,,-.
The Central Andes region is considered an area of high environmental relevance in South America and it is rich in glaciers, which are the main fresh water sources and reservoirs of the region. The presence of organochlorine compounds (OCs) is an environmental threat due to their persistence and adverse effects on wildlife and humans. The levels of OCs, such as chlordane compounds (CHLs), dichlorodiphenyltrichloroethane and metabolites (DDTs), hexachlorobenzene (HCB), hexachlorocyclohexanes (HCHs), and polychlorinated biphenyls (PCBs), were determined in muscle and liver tissues of fish and in sediments collected from different sites of the central Andes: the Mendoza River and the Yaucha River (rainbow trout: Oncorhynchus mykiss) and Carrizal Dam (silverside: Odontesthes bonariensis). Regardless of studied site and fish tissue, the general OC trend was: DDTs > PCBs > HCHs > CHLs > HCB. The results showed clear geographic distribution patterns for DDTs. Among the sampling sites, silverside fish showed the highest average load of DDTs (614 and 867 ng g−1 lw in muscle and liver tissues, respectively). Based on the biota-sediment bioaccumulation factor (BSAF), both rainbow trout and silverside fish showed comparable capability to accumulate p,p′-DDT in their tissues. Intraspecific correlational analysis showed that CB-138 in muscle and p,p′-DDT in liver were clearly correlated with the lipid content in silverside specimens, which highlights the relevance of taking into account the fat content and the type of target tissues.
Berton, P ;Mammana, SB ; Locatelli, DA ; Lana, NB ; Hapon, MB ; Camargo, AB ; Altamirano, JC ; ,2017 ,38 ,460 -468 .
Ultrasound-assisted extraction (UAE), cloud point extraction (CPE), and ultrasound back-extraction (UABE) techniques have been coupled for lixiviation, preconcentration, and cleanup of polybrominated diphenyl ethers (PBDEs) from milk samples for determination by gas chromatography-electron capture detection (GC-ECD). Physicochemical parameters that affect the efficiency of the extraction system were investigated using a design of experiments based on multivariate statistical tools, and considering the sample matrix along the development. The coupling of the leaching step, UAE, enhanced ca. 3.5 times the extraction efficiency of the former sample preparation methodology (CPE-UABE) leading to cleaner sample extracts suitable for GC analysis. Under optimum conditions, the proposed methodology exhibits successful performance in terms of linearity and precision, with recoveries in the range of 68–70% and LODs within the range 0.05–0.5 ng/g dry weight (d.w.). The proposed sample preparation methodology coupled three green analytical techniques. It expands the application frontiers of CPE for the analysis of biological samples by GC. The optimized methodology was used for determination of PBDEs in powder milk samples, from both commercial and human sources.
Hunzicker, GA ;Hein, GJ ; Baldo, MN ; Hernandez, SR ; Altamirano, JC ; ,2016 ,3 ,157 -168 .
A pharmacokinetic study based on single oral administration of Tenofovir disoproxil fumarate 300 mg (tablets) to Argentinean male volunteers under fasting conditions is presented. The obtained values for test and reference products were 238±62 and 261±73 ng mL-1 for Cmax; 1658±466 and 1801±529 ng mL-1 h for AUC0–48h; 1845±579 and 2015±639 ng mL-1 h for AUC0–∞, respectively. The 90% confidence intervals obtained by analysis of variance were 85.0-97.2% for ln-Cmax, 87.2-97.9% for ln-AUC0–48h and 85.5-98.1% for ln-AUC0–∞, which are within the acceptance range of 80-125%. Both products were bioequivalent in terms of rate and extent of drug absorption and therefore interchangeable. The analytical methodology was optimized and validated for determination of Emtricitabine (FTC), Lamivudine (3TC) and Tenofovir (TFV) in human plasma samples; which is the pharmaceutical combination most commonly used for treating HIV-infected patients. The analytical methodology was based on solid phase extraction (SPE) using Oasis® MCX mixed-mode cartridges coupled to Liquid Chromatography and electrospray tandem mass spectrometry (LC-ESI-MS/MS). The analytical methodology was validated according to the US Food and Drug Administration guidelines. Under optimized conditions, the analytical methodology lead to work within a clinical of 11-5434, 11-5452 and 13-397 ng mL-1 for FTC, 3TC and TFV, respectively; resulting wider than others previously reported. The intra and inter batch precision (%RSD) across three validation runs was less than 14%. The accuracy determined at four QC levels (LOQ, Low, Middle and High) was within 13%, in terms of percent relative error.
Allende, D ;Ruggeri, MF ; Lana, B ; Garro, K ; Altamirano, JC ; Puliafito, E ; ,2015 ,,1 -12 .
The setting up of a country or region-based inventory is considered a crucial step toward the elimination of worldwide persistent organic pollutants (POPs) contamination. Moreover, the need of comparable emission inventories at city or region level is widely recognized to develop evidence-based policies accounting for the relation between emissions and institutional, socio-economic and demographic characteristics at small scale level. Due to the low spatial and temporal resolution of the available measurements, highly variable air concentrations of several POPs have been observed in Latin American and Caribbean countries. This paper presents a high resolution spatially disaggregated atmospheric emission inventory for selected POPs in order to assess the environmental fate of some of these compounds in a finer resolution. As study case we estimated releases to air of POPs in a typical mid-size urban conglomeration in Argentina. Inventoried compounds were total polychlorinated biphenyls (PCBs), total polybrominated diphenyl ethers (PBDEs), total dichlorodiphenyltrichloroethane (DDT) on a sum basis, hexachlorobenzene (HCB) and dioxins and furans (PCDD/Fs), for which emissions were estimated in 0.92 kg/year, 1.65 kg/year, 4.2E−02 kg/year (total sum of congeners), 0.86 kg/year and 4.4E−02 kg/year respectively, values that are in accordance with the geographic and economic context. Although emitting sources are quite varied, there are very clear trends, particularly in relation to open burning of municipal solid waste and agrochemical use as major contributors. Overall, the inventory provides valuable data for the analysis of the heterogeneity of POP emissions and the necessary inputs for air quality modeling.
Rios, JM ;Lana, NB ; Berton, P ; Ciocco, NF ; Altamirano, JC ; EMERGING CONTAMINANTS ,2015 ,,54 -63 .
Certain wild animals represent sentinels to address issues related to environmental pollution, since they can provide integrative data on both pollutant exposure and biological effects. Despite their technological benefits, PBDEs are considered a threat to environmental health due to their persistence, toxicity, and capacity to be accumulated. These pollutants have been found geographically widespread in fish, particularly in predator species such as trout. The aim of this work is to critically review the applicability and usefulness of wild trout for assessing PBDEs in freshwater environments. Reviewed reports include data from highly industrialized areas as well as areas from remote regions with relatively low human activity, including European and North American great lakes and freshwater environments in Europe, Greenland, subarctic areas and Patagonia, respectively. A summary of relevant factors were grouped into organism-specific factors (food habits, age, size, lipid content, sex and reproduction, tissue type, mechanism of contaminant uptake and metabolism), and PBDE levels in the surrounding environment (sediment). Five wild trout species [rainbow trout (Oncorhynchus mykiss), brown trout (Salmo trutta), lake trout (Salvelinus namaycush), arctic char (Salvelinus alpinus), and brook trout (Salvelinus fontinalis)], collected worldwide within the 1994 to present time frame, were considered. Multivariate techniques (principal component analysis-PCA) and mapping approach, showed clear differences in geographic distribution patterns of PBDE levels in trout depending on the region studied: wild trout from European and North American great lakes have the highest PBDE loads. This pattern could be due to high industrial activity at these locations. A correlational approach used to explore intraspecific relationships between PBDE levels and morphometry, showed positive relationships only for brown trout. Further, brown trout showed the highest trout-to-sediment ratios, which is suggestive of a relatively greater capacity of this species to accumulate PBDEs in relation to sediment levels. Overall, results suggest that adult wild trout could be useful as a PBDE bioindicator.
Hunzicker, GA ;Hein, GJ ; Hernandez, SR ; Altamirano, JC ; ANALYTICAL CHEMISTRY RESEARCH ,2015 ,6 ,1 -8 .
An analytical methodology based on cloud point extraction (CPE) coupled to Ultra-Fast Liquid Chromatography and electrospray tandem mass spectrometry (UFLC-MS/MS) was developed for analysis of Abacavir (ABC), Efavirenz (EFV), Lamivudine (3 TC) and Nelfinavir (NFV) in human plasma. It is the first time that CPE was used for extraction of antiretrovirals (ARV) from plasma. The effects of relevant physic-chemical variables on analytical response of each ARV, including pH, surfactant concentration, equilibration time and temperature, were study and optimized; as well as its coupling to UFLC-ESI-MS/MS. Under optimized conditions, the resulting methodology was as follows: a 500 μL aliquot of human plasma was diluted with 2 mL deionized water in a 10 mL centrifuge tube. A 500 μL aliquot Triton X-114 5% w/v was added and homogenized using a vortex stirrer. The resulting cloudy solution was kept at 65 °C for 20 min for promoting the condensation of surfactant micelles. Then it was centrifuged at 3000 × g for 5 min for separation of the surfactant-rich phase. After discarding the aqueous supernatant, 400 μL ACN were added to the remaining surfactant rich phase and centrifuged in order to precipitate proteins and separate them. A 150 μL aliquot of the supernatant was transferred to 2 mL vial and further diluted with 400 μL deionized water. A 30 μL aliquot of the so-prepared solution was injected and analyzed into the UFLC-MS/MS. The method detection limits for ABC, EFV, 3 TC and NFV under optimized conditions were 31, 77, 57 and 21 ng mL−1, respectively. The RSD% for the studied analytes were <15%, except at the LOQ, which were <19%. Recovery values ranged from 81 to 107%. The proposed methodology was successfully applied for the analysis of ABC, EFV, 3 TC and NFV in human plasma within the concentration range of 43–6816, 125–4992, 81–3248 and 49–7904 ng mL−1, respectively. Under optimized working conditions the proposed analytical methodology meets standard requirements of international guidelines, which makes it suitable for pharmacokinetic studies of the four ARV, as well as for therapeutic monitoring of HIV patients.
Baldo, MN ;Hunzicker, GA ; Altamirano, JC ; Murguia, MC ; Hein, GJ ; JOURNAL OF BIOEQUIVALENCE & BIOAVAILABILITY ,2015 ,,108 -111 .
The study was performed to compare the bioavailability of two ketoprofen capsule (50 mg) formulations: Flogofin®, as test formulation, and Profenid®, as reference formulation. The study was conducted open with randomized two period crossover design and 1 week washout period in 24 fasting, healthy latino-american male volunteers and performed at the Biopharmaceutical Research Center Dominguez Lab. After dosing, serial blood samples were collected for a period of 24 h and plasma was separated and analyzed for ketoprofen, using a sensitive, reproducible, and accurate method by liquid chromatography ? tandem mass spectrometry (LC-MS/MS). Pharmacokinetic parameters: AUC0-24, AUC0-∞, Cmax, Tmax, T1/2 and Ke, were analyzed from plasma concentrations of both formulations. The means AUC0-24 for test and reference formulation were 50.21 ([μg h]/mL) - 50.28 ([μgh]/mL), 52.38 ([μg h]/mL) - 50.84 ([μg h]/mL) for AUC0-∞, and 21.58 μg/mL - 21.65 μg/mL for Cmax, respectively. Statistical modules (ANOVA and 90% confidence intervals) were applied to AUC0?24, AUC0-∞, and Cmax to assess the bioequivalence of the two brands which revealed no significant difference between them, and 90% CI fell within the accepted bioequivalence range of 80%-125%. Based on these statistical inferences, both formulations were found to be bioequivalent.
Dellagnola, FA ;Rodriguez, C ; Castro Vazquez, A ; Vega, IA ; ,2019 ,,-.
We here compare morphological and molecular characters of some putative endosymbiotic elements of the digestive gland of three ampullariid species (Pomacea canaliculata, Pomacea scalaris and Asolene platae) which coexist in Lake Regatas (Palermo, Buenos Aires). The putative endosymbionts were reported in these species and were identified as C and K corpuscles. The three species show tubuloacinar glands, each adenomere was constituted mainly by two distinct cell types (columnar and pyramidal). C and K corpuscles together occupied from one-fourth to one-fifth of the tissue area in the three host species, where C corpuscles were round and greenish-brown, were delimited by a distinct wall, stained positively with Alcian Blue and were associated with columnar cells. K corpuscles were oval, dark-brown multilamellar bodies and were associated with pyramidal cells. Under TEM, C corpuscles occurred within vacuoles of columnar cells and contained many electron-dense clumps and irregular membrane stacks and vesicles spread in an electron-lucent matrix. Sometimes a membrane appeared detached from the inner surface of the wall, suggesting the existence of a plasma membrane. In turn, K corpuscles were contained within vacuoles of pyramidal cells and were made of concentric lamellae, which were in turn made of an electron-dense fibrogranular material. No membranes were seen in them. Interspecifically, C corpuscles vary significantly in width and inner contents. K corpuscles were also variable in length and width. However, both C and K corpuscles in the three studied species hybridised with generalised cyanobacterial/chloroplast probes for 16S rRNA. Also, both corpuscle types (isolated from gland homogenates) were sensitive to lysozyme digestion, which indicates that bacterial peptidoglycans are an integral part of their covers. The reported data confirm and extend previous studies on P. canaliculata in which the endosymbiotic nature of C and K corpuscles were first proposed. We further propose that the endosymbiotic corpuscles are related to the Cyanobacteria/chloroplasts clade. Based on the known distribution of these corpuscles in the major clades of Ampullariidae, we hypothesise they may be universally distributed in this family, and that may constitute an interesting model for studying the co-evolution of endosymbionts and their gastropod hosts.
Escpbar Correas, S ;Mendoza Porras, O ; Dellagnola, FA ; Colgrave, M ; Vega, IA ; JOURNAL OF PROTEOME RESEARCH ,2019 ,18 ,3342 -3352 .
The freshwater snail Pomacea canaliculata, an invasive species of global significance, possesses a well-developed digestive system and diverse feeding mechanisms enabling the intake of a wide variety of food. The identification of glycosidases in adult snails would increase the understanding of their digestive physiology and potentially generate new opportunities to eradicate and/or control this invasive species. In this study, liquid chromatography coupled to tandem mass spectrometry was applied to define the occurrence, diversity, and origin of glycoside hydrolases along the digestive tract of P. canaliculata. A range of cellulases, hemicellulases, amylases, maltases, fucosidases, and galactosidases were identified across the digestive tract. The digestive gland and the contents of the crop and style sac yield a higher diversity of glycosidase-derived peptides. Subsequently, peptides derived from 81 glycosidases (46 proteins from the public database and 35 uniquely from the transcriptome database) that were distributed among 13 glycoside hydrolase families were selected and quantified using multiple reaction monitoring mass spectrometry. This study showed a high glycosidase abundance and diversity in the gut contents of P. canaliculata, which participate in extracellular digestion of complex dietary carbohydrates. Salivary and digestive glands were the main tissues involved in their synthesis and secretion.
Giraud Billoud, M ;Rivera Ingraham, GA ; Moreira, DC ; Burmester, T ; Castro Vazquez, A ; Carvajalino Fernandez, JM ; Dafre, A ; Niu, C ; Tremblay, N ; Paital, B ; Rosa, R ; Storey, JM ; Vega Israel, A ; Zhang, W ; Yepiz Plascencia, G ; Zenteno Savin, T ; Storey, KB ; Hermes Lima, M ; COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY ,2019 ,234 ,36 -49 .
Freezing, dehydration, salinity variations, hypoxia or anoxia are some of the environmental constraints that many organisms must frequently endure. Organisms adapted to these stressors often reduce their metabolic rates to maximize their chances of survival. However, upon recovery of environmental conditions and basal metabolic rates, cells are affected by an oxidative burst that, if uncontrolled, leads to (oxidative) cell damage and eventually death. Thus, a number of adapted organisms are able to increase their antioxidant defenses during an environmental/functional hypoxic transgression; a strategy that was interpreted in the 1990s as a “preparation for oxidative stress” (POS). Since that time, POS mechanisms have been identified in at least 83 animal species representing different phyla including Cnidaria, Nematoda, Annelida, Tardigrada, Echinodermata, Arthropoda, Mollusca and Chordata. Coinciding with the 20th anniversary of the postulation of the POS hypothesis, we compiled this review where we analyze a selection of examples of species showing POS-mechanisms and review the most recent advances in understanding the underlying molecular mechanisms behind those strategies that allow animals to survive in harsh environments.
Sun, J ;Mu, H ; Ip, JCH ; Li, R ; Zhang, Y ; Xu, T ; Kumagai, N ; Yusa, Y ; Accorsi, A ; Sanchez Alvarado, A ; Ross, E ; Castro Vazquez, A ; Vega, IA ; Heras, H ; Ituarte, S ; Van Bocxlaer, B ; Hayes, KA ; Cowie, RH ; Zhao, Z ; Zhang, Y ; Qian, PY ; Qiu, JW ; MOLECULAR BIOLOGY AND EVOLUTION ,2019 ,36 ,1507 -1520 .
The family Ampullariidae includes both aquatic and amphibious apple snails. They are an emerging model for evolutionary studies due to the high diversity, ancient history, and wide geographical distribution. Insight into drivers of ampullariid evolution is hampered, however, by the lack of genomic resources. Here, we report the genomes of four ampullariids spanning the Old World (Lanistes nyassanus) and New World (Pomacea canaliculata, P. maculata, and Marisa cornuarietis) clades. The ampullariid genomes have conserved ancient bilaterial karyotype features and a novel Hox gene cluster rearrangement, making them valuable in comparative genomic studies. They have expanded gene families related to environmental sensing and cellulose digestion, which may have facilitated some ampullarids to become notorious invasive pests. In the amphibious Pomacea, novel acquisition of an egg neurotoxin and a protein for making the calcareous eggshell may have been key adaptations enabling their transition from underwater to terrestrial egg deposition.
Giraud Billoud, M ;Castro Vazquez, A ; Campoy Diaz, AD ; Giuffrida, PM ; Vega, IA ; COMPARATIVE BIOCHEMISTRY & PHYSIOLOGY ,2018 ,224 ,129 -137 .
Pomacea canaliculata may serve as a model organism for comparative studies of oxidative damage and antioxidant defenses in active, hibernating and arousing snails. Oxidative damage (as TBARS), free radical scavenging capacity (as ABTS+ oxidation), uric acid (UA) and glutathione (GSH) concentrations, activities of superoxide dismutase (SOD) and catalase (CAT), and the protein expression levels of heat shock proteins (Hsp70, Hsc70, Hsp90) were studied in digestive gland, kidney and foot. Tissue TBARS of hibernating snails (45 days) was higher than active snails. Hibernation produced an increase of ABTS+ in digestive gland, probably because of the sustained antioxidant defenses (UA and/or GSH and SOD levels). Kidney protection during the activity-hibernation cycle seemed provided by increased UA concentrations. TBARS in the foot remained high 30 min after arousal with no changes in ABTS+, but this tissue increased ABTS+ oxidation at 24 h to expenses increased UA and decreased GSH levels, and with no changes in SOD and CAT activities. The level of Hsp70 in kidney showed no changes throughout the activity-hibernation cycle but it increased in the foot after hibernation. The tissue levels of Hsp90 in snails hibernating were higher than active snails and returned to baseline 24 h after arousal. Results showed that chronic cooling produces a significant oxidative damage in three studied tissues and that these tissue damages are overcome quickly (between 30 min to 24 h) with fluctuations in different antioxidant defenses (UA, GSH, CAT) and heat shock proteins (Hsp70 and Hsp90).
Marone, L ;Lopez de Casenave, J ; Gonzalez del Solar, R ; JOURNAL OF HUMANITIES ,2019 ,14 ,366 -373 .
There are currently serious concerns that published scientific findings often fail to be reproducible, and that some solutions may be gleaned by attending the several methodological and sociological recommendations that could be found in the literature. However, researchers would also arrive at some answers by considering the advice of the philosophy of science, particularly semantics, about theses on truth related to scientific realism. Sometimes scientists understand the correspondence thesis of truth (CTT) as asserting that the next unique empirical confirmation of a hypothesis suffices to attribute truth to it provisionally. Such empiricist bias is not necessarily at the core of CTT, but Mario Bunge proposed the synthetic thesis of truth (STT), based on CTT, to explicitly avoid the bias. STT requires considering a hypothesis corroborated, both by purely empirical confirmation and external consistency or compatibility with the bulk of existing background knowledge (systemicity). While a capricious understanding of CTT could be rigged to recommend the “one shot game” in hypothesis testing, STT clearly demands the use of multiple approaches, empirical as well as theoretical, and it asserts that a scientific test is effective to the extent to which it is neither purely empirical, nor viewed in isolation. Pattern consistency (empirical control) together with an understanding of causal relations (rational together with empirical control) make confirmed hypotheses robust and more reliable. The militancy of the double mechanism of hypothesis control of STT can help mitigate the reproducibility crisis. Earl Werner’s research program in community ecology is an example of the (implicit) use of STT criteria, which leads to the development of reliable, cross-checked, ecological results, with high predictive capacity.
Miretti, MF ;Lopez de Casenave, J ; Pol, RG ; ARTHROPOD-PLANT INTERACTIONS ,2019 ,13 ,771 -788 .
The harvester ant Pogonomyrmex mendozanus is endemic to the central Monte desert. In this region, extensive grazing reduces grass cover and seed abundance in the soil bank. In previous studies carried out in ungrazed areas, this ant species consumes and prefers seeds of perennial grasses over forbs and shrubs. However, in grazed habitats, P. mendozanus expands its diet by including seeds from other plant groups along with fruits, dead arthropods and other non-seed items. The broader diet could be due to a flexible foraging strategy or could reflect intrinsic, context-dependent food preferences of the populations inhabiting heavy grazed areas, different from those populations studied under ungrazed conditions. We carried out food preference experiments in heavy grazed areas in the central Monte desert in order to discriminate between both hypotheses. We performed choice experiments using a paired comparison design, offering seeds and non-seed food items present in the diet of P. mendozanus. Ants preferred large- and medium-sized perennial grass seeds and, among the non-seed food items, arthropods were preferred. Forb and shrub seeds along with fruits showed intermediate preference levels, whereas the least preferred items were small grass seeds and flowers. Food preferences were similar to those reported previously in ungrazed conditions, supporting the hypothesis that seed preferences are stereotyped in this species and strongly suggesting that it behaves as an expansive specialist by including less preferred items in its diet in heavy grazed habitats where the most preferred seeds are scarce.
Miranda, EN ;JOURNAL OF MODERN PHYSICS ,2015 ,6 ,1051 -1057 .
We study the statistical mechanics of small clusters (N ~ 10 - 100) for two-level systems and harmonic oscillators. Both Boltzmann’s and Gibbs’s definitions of entropy are used. The properties of the studied systems are evaluated numerically but exactly; this means that Stirling’s approximation was not used in the calculation and that the discrete nature of energy was taken into account. Results show that, for the two-level system, using Gibbs entropy prevents temperatures from assuming negative values; however, they reach very high values that are not plausible in physical terms. In the case of harmonic oscillators, there are no significant differences when using either definition of entropy. Both systems show that for N = 100 the exact results evaluated with statistical mechanics coincide with those found in the thermodynamic limit. This suggests that thermodynamics can be applied to systems as small as these.
Bertoldi, DS ;Fernandez Guillermet, A ; Miranda, EN ; REVISTA MEXICANA DE FISICA ,2016 ,62 ,60 -65 .
We study the simplest possible model of nanocrystal consisting in a simple cubic lattice with a small number of atoms (NA ∼ 10−103), where each atom is linked to its nearest neighbor by a quantum harmonic potential. Some properties (entropy, temperature, speciﬁc heat) of the nanocrystal are calculated numerically but exactly within the framework of the microcanonical ensemble. We ﬁnd that the presence of a surface in the nanocrystal modiﬁes the thermostatistic properties to a greater extent than the small number of atoms in the system. The speciﬁc heat Cv behaves similarly to the Einstein solid, with an asymptotic value for high temperatures that differs from that of the Dulong-Petit law by a term of the order of N−1/3 A and that can be explained easily in terms of the surface. The entropy is non-additive, but this is due to the presence of the surface and we show that the additivity is recovered in the thermodynamic limit. Finally, we ﬁnd that, when calculations follow the canonical ensemble, results differ little for small systems (NA = 27) and are inexistent for larger systems (NA = 1000).
Miranda, EN ;REVISTA BRASILEIRA DE ENSINIO DE FISICA ,2016 ,38 ,-.
Heat conduction along an isolated bar placed between two reservoirs at diﬀerent temperatures is studied. The entropy production is considered in detail with two diﬀerent approaches. In the ﬁrst one, the whole system (the bar and the two reservoirs) is analysed in the steady state with the help of standard thermodynamics. In the second one, the bar is divided into n cells and a simple ﬁnite diﬀerence method is used to evaluate the time evolution of the entropy production. This approach is useful because the transient behaviour can be studied. In this way, it is shown a simple example of a non-equilibrium system where the entropy production (even its transient behaviour) can be evaluated with tools at hand of a motivated undergraduate.
Miranda, EN ;Mora Barzaga, G ; JOURNAL OF MODERN PHYSICS ,2019 ,10 ,601 -612 .
The question here is whether the Debye model is suited to evaluate the specific heat of nanocrystals. For this, the simplest possible nanocrystal is considered: a basic cubic structure made of atoms that interact through a harmonic potential. This simple model can be solved exactly. This allows the dispersion relation of the mechanical waves to be determined, so that calculating the exact specific heat turns out to be quite straightforward. Then, the same problem is solved using the Debye approximation. Our findings show that the specific heat of a nanocrystal evaluated exactly is higher than the value found in the thermodynamic limit, that is to say, the specific heat decreases as the nanocrystal size increases. In addition, it becomes clear that the Debye model is a poor approximation for calculating the specific heat of a nanocrystal. Naturally, the Einstein model yields an even worse result. The cause of the discrepancy is found in the role of the nanocrystal surface.
Miranda, EN ;EUROPEAN JOURNAL OF PHYSICS ,2019 ,40 ,065401 -.
We consider the known problem of a particle in a one-dimensional box, i.e. in an inﬁnite potential well. Speciﬁcally, we evaluate the probability density for ﬁnding a particle in a certain position when the system is in contact with a reservoir at a temperature T≠0. We observe that, when the T is increased, the density tends to become uniform in the box, except in a ‘boundary layer’ close to the walls. Then, we consider two particles in the box, discriminating between bosons and fermions. The particles are ﬁrst analyzed without accounting for the spin. Evaluating the thermalized probability density in this way, results in a clear difference between bosons and spinless fermions. Next, we consider the complete wave function for spin-½fermions, and the probability density changes signiﬁcantly with respect to the spinless case. This shows that disregarding the electron spin for the sake of simplicity may lead to misleading results.
Mouna, L ;Hernandez, E ; Bonte, D ; Brost, R ; Amazit, L ; Delgui, LR ; Brune, W ; Geballe, AP ; Beau, I ; Esclatine, A ; ,2016 ,12 ,327 -42 .
Autophagy is activated early after human cytomegalovirus (HCMV) infection but, later on, the virus blocks autophagy. Here we characterized 2 HCMV proteins, TRS1 and IRS1, which inhibit autophagy during infection. Expression of either TRS1 or IRS1 was able to block autophagy in different cell lines, independently of the EIF2S1 kinase, EIF2AK2/PKR. Instead, TRS1 and IRS1 interacted with the autophagy protein BECN1/Beclin 1. We mapped the BECN1-binding domain (BBD) of IRS1 and TRS1 and found it to be essential for autophagy inhibition. Mutant viruses that express only IRS1 or TRS1 partially controlled autophagy, whereas a double mutant virus expressing neither protein stimulated autophagy. A mutant virus that did not express IRS1 and expressed a truncated form of TRS1 in which the BBD was deleted, failed to control autophagy. However, this mutant virus had similar replication kinetics as wild-type virus, suggesting that autophagy inhibition is not critical for viral replication. In fact, using pharmacological modulators of autophagy and inhibition of autophagy by shRNA knockdown, we discovered that stimulating autophagy enhanced viral replication. Conversely, inhibiting autophagy decreased HCMV infection. Thus, our results demonstrate a new proviral role of autophagy for a DNA virus.
Tohme, MJ ;Gimenez, MC ; Colombo, MI ; Peralta, A ; Delgui, LR ; JOURNAL OF ANTIMICROBIAL AGENTS ,2019 ,,-.
Rotavirus is one of the leading causes of severe acute gastroenteritis in children under 5 years of age, mainly affecting developing countries. Once the disease is acquired, no specific treatment is available; as such, the development of new drugs for effective antirotaviral treatment is critical. Ursolic acid is a pentacyclic triterpenoid with antiviral activity, which has been studied extensively in vitro and in vivo. To study the potential antirotaviral activity of ursolic acid, its toxic potential for viral particles (virucidal effect) and cultured cells (cytotoxicity) was analysed. No effect on virion infectivity was observed with treatments of up to 40 µM ursolic acid, while incipient cytotoxicity started to be evident with 20 µM ursolic acid. The antiviral potential of ursolic acid was evaluated in in-vitro rotavirus infections, demonstrating that 10 µM ursolic acid inhibits rotavirus replication (observed by a decrease in viral titre and the level of the main viral proteins) and affects viral particle maturation (a process associated with the endoplasmic reticulum) 15 h post infection. Interestingly, ursolic acid was also found to hamper the early stages of the viral replication cycle, as a significant reduction in the number and size of viroplasms, consistent with a decrease in VP6 and NSP2 viral proteins, was observed 4 h post infection. As such, these observations demonstrate that ursolic acid exhibits antiviral activity, suggesting that this chemical could be used as a new treatment for rotavirus.
Crosio, MA ;Via, MA ; Camara, CI ; Mangiarotti, A ; Del Popolo, MG ; Wilke, N ; ,2019 ,,-.
The membrane translocation efficiency of cell penetrating peptides (CPPs) has been largely studied, and poly-arginines have been highlighted as particularly active CPPs, especially upon negatively charged membranes. Here we inquire about the influence of membrane mechanical properties in poly-arginine adsorption, penetration and translocation, as well as the subsequent effect on the host membrane. For this, we selected anionic membranes exhibiting different rigidity and fluidity, and exposed them to the nona-arginine KR9C. Three different membrane compositions were investigated, all of them having 50% of the anionic lipid 1,2-dioleoyl-sn-glycero-3-phospho-(1’-rac-glycerol) (DOPG), thus, ensuring a high affinity of the peptide for membrane surfaces. The remaining 50% was a saturated PC (1,2-dipalmitoyl-sn-glycero-3-phosphocholine, DPPC), an unsaturated PC (1,2-dioleoyl-sn-glycero-3-phosphocholine, DOPC) or a mixture of DOPC with cholesterol. Peptide-membrane interactions were studied using four complementary models for membranes: Langmuir monolayers, Large Unilamellar Vesicles, Black Lipid Membranes and Giant Unilamellar Vesicles. The patterns of interaction of KR9C varied within the different membrane compositions. The peptide strongly adsorbed on membranes with cholesterol, but did not incorporate or translocate them. KR9C stabilized phase segregation in DPPC/DOPG films and promoted vesicle rupture. DOPC/DOPG appeared like the better host for peptide translocation: KR9C adsorbed, inserted and translocated these membranes without breaking them, despite softening was observed.
Ruete, MC ;Zarelli, VEP ; Masone, D ; De Paola, M ; Bustos, DM ; Tomes, CN ; ,2019 ,,-.
N-ethylmaleimide-sensitive factor (NSF) disassembles fusion-incompetent cis soluble-NSF attachment protein receptor (SNARE) complexes making monomeric SNAREs available for subsequent trans pairing and fusion. In most cells the activity of NSF is constitutive, but in Jurkat cells and sperm it is repressed by tyrosine phosphorylation; the phosphomimetic mutant NSF–Y83E inhibits secretion in the former. The questions addressed here are if and how the NSF mutant influences the configuration of the SNARE complex. Our model is human sperm, where the initiation of exocytosis (acrosome reaction (AR)) de-represses the activity of NSF through protein tyrosine phosphatase 1B (PTP1B)-mediated dephosphorylation. We developed a fluorescence microscopy-based method to show that capacitation increased, and challenging with an AR inducer decreased, the number of cells with tyrosine-phosphorylated PTP1B substrates in the acrosomal domain. Results from bioinformatic and biochemical approaches using purified recombinant proteins revealed that NSF–Y83E bound PTP1B and thereupon inhibited its catalytic activity. Mutant NSF introduced into streptolysin O-permeabilized sperm impaired cis SNARE complex disassembly, blocking the AR; subsequent addition of PTP1B rescued exocytosis. We propose that NSF–Y83E prevents endogenous PTP1B from dephosphorylating sperm NSF, thus maintaining NSF’s activity in a repressed mode and the SNARE complex unable to dissociate. The contribution of this paper to the sperm biology field is the detection of PTP1B substrates, one of them likely being NSF, whose tyrosine phosphorylation status varies during capacitation and the AR. The contribution of this paper to the membrane traffic field is to have generated direct evidence that explains the dominant-negative role of the phosphomimetic mutant NSF–Y83E.
Sagario, MC ;Cueto, VR ; Zarco, A ; Pol, RG ; Marone, L ; AGRICULTURE ECOSYSTEMS & ENVIRONMENT ,2019 ,,-.
Numerical responses of animals to habitat perturbation often seem inconsistent, spreading skepticism about the predictive capacity of applied ecology. Domestic grazing changes several habitat variables that can affect seed-eating birds. Birds, in turn, show adaptations (e.g. in their feeding behavior) that could allow them to overcome habitat perturbations. Here we modelled habitat variables (e.g. cover of different plants, panicles, soil seed bank) in grazed and ungrazed (or lightly grazed) habitats of the central Monte desert, Argentina, to detect those affected by grazing activity. There was no effect of grazing on shrub and tree cover, but grazing reduced the abundance mostly of large grass seeds but also of small grass and forb seeds. Then, we used model’s outputs and knowledge of feeding preferences of the five most common seed-eating passerines in the Monte to make species-specific predictions: changes in abundance of grass seed specialists (Saltatricula multicolor, Microspingus torquatus and Porphyrospiza carbonaria) due to grazing activity should be consistent and should depend on large grass seeds (i.e. preferred seeds), whereas changes in abundance of more generalist species (Zonotrichia capensis and Diuca diuca) should be less consistent and explained also by the abundance of other seeds. The abundance of large grass seeds was sufficient to predict the abundances of S. multicolor, M. torquatus and P. carbonaria. The best model for predicting the abundance of Z. capensis included large grass seeds as well as small grass or forb seeds. No model including the abundance of seeds predicted the abundance of D. diuca. Therefore, feeding behavior explained the abundance of four out of the five bird species. A review of the literature showed that feeding behavior is also a good predictor of habitat use in other desert grasslands. Conservative range management should consider, and even manipulate, the level of the seeds preferred by wildlife. Grazed grasslands should be rested from grazing on a rotational basis so that grasses, especially those whose seeds are preferred by birds, can seed.
Gonzalez del Solar, R ;Marone, L ; Lopez de Casenave, R ; ,2019 ,,-.
The search for mechanisms has been a common practice in scientific research. However, since the empiricist critique of causality, and especially during the second third of the twentieth century, other non-mechanistic perspectives—especially deductivism—gained predominance. But the sustained effort of authors such as Michael Scriven, Mario Bunge and especially Wesley Salmon contributed to restoring the respectability of causality and mechanisms in philosophy of science. Some members of the causal family, usually lumped under the name of “new mechanistic philosophy”, emphasize the description of mechanisms, especially causal ones, as a central aspect of explanation and other research practices in several areas of science. This approach offers viable solutions to the various ontological and methodological objections that are opposed to the two traditional approaches (the purely deductive and the purely causal). In this work the basic characteristics of three philosophies that highlight the description of mechanisms as a central element to explanation and their suitability for the science of ecology are discussed.
Ramirez, PG ;Del Popolo, MG ; Vila, JA ; Szleifer, I ; Longo, GS ; JOURNAL OF COLLOID AND INTERFACE SCIENCE ,2019 ,552 ,701 -711 .
The mechanism that arginine-rich cell penetrating peptides (ARCPPs) use to translocate lipid membranes is not entirely understood. In the present work, we develop a molecular theory that allows to investigate the adsorption and insertion of ARCPPs on membranes bearing hydrophilic pores. This method accounts for size, shape, conformation, protonation state and charge distribution of the peptides; it also describes the state of protonation of acidic membrane lipids. We present a systematic investigation of the effect of pore size, peptide concentration and sequence length on the extent of peptide adsorption and insertion into the pores. We show that adsorption on the intact (non-porated) lipid membrane plays a key role on peptide translocation. For peptides shorter than nona-arginine, adsorption on the intact membrane increases significantly with chain length, but it saturates for longer peptides. However, this adsorption behavior only occurs at relatively low peptide concentrations; increasing peptide concentration favors adsorption of the shorter molecules. Adsorption of longer peptides increases the intact membrane negative charge as a result of further deprotonation of acidic lipids. Peptide insertion into the pores depends non-monotonically on pore radius, which reflects the short range nature of the effective membrane-peptide interactions. The size of the pore that promotes maximum adsorption depends on the peptide chain length. Peptide translocation is a thermally activated process, so we complement our thermodynamic approach with a simple kinetic model that allows to rationalize the ARCPPs translocation rate in terms of the free energy gain of adsorption, and the energy cost of creating a transmembrane pore with peptides in it. Our results indicate that strategies to improve translocation efficiency should focus on enhancing peptide adsorption. (C) 2019 Elsevier Inc. All rights reserved.
Rivero, G ;Aldana, AA ; Lopez, YRF ; Liverani, L ; Boccacini, AR ; Bustos, DM ; Abraham, GA ; JOURNAL OF MATERIALS SCIENCE-MATERIALS IN MEDICINE ,2019 ,30 ,-.
Adipose-derived mesenchymal stem cells (ASCs) accelerate the osteointegration of bone grafts and improve the efficiency in the formation of uniform bone tissue, providing a practical and clinically attractive approach in bone tissue regeneration. In this work, the effect of nanofibrous biomimetic matrices composed of poly(epsilon-caprolactone) (PCL), nanometric hydroxyapatite (nHA) particles and 14-3-3 protein isoform epsilon on the initial stages of human ASCs (hASCs) osteogenic differentiation was investigated. The cells were characterized by flow cytometry and induction to differentiation to adipogenic and osteogenic lineages. The isolated hASCs were induced to differentiate to osteoblasts over all scaffolds, and adhesion and viability of the hASCs were found to be similar. However, the activity of alkaline phosphatase (ALP) as early osteogenic marker in the PCL-nHA/protein scaffold was four times higher than in PCL-nHA and more than five times than the measured in neat PCL.
Gomez, L ;Canizo, B ; Lana, B ; Zalazar, G ; Wuilloud, R ; Aravena, R ; JOURNAL OF IBERIAN GEOLOGY ,2019 ,45 ,365 -382 .
Northeastern Mendoza is an arid area dominated by stabilized dunes and paleochannels. Groundwater is the main source of water for domestic and subsistence economy. Two types of wells are used for groundwater withdrawal. Wells operated by conventional windmills or pumps (Ws) and local traditional bucket wells operated manually (BWs). These wells are drugged a few cm below the water table, normally with a diameter of 1 m, remain always open and are located near corrals. The aim of this study was to evaluate the processes that control As in groundwater used As drinking water by rural communities. The study approach included an assessment of the natural as background levels and the use of environmental isotopes (delta O-18 and delta H-2) to determine the origin of groundwater and improve the conceptual model for groundwater flow. Significant statistical differences were found between the chemical features of groundwater from Ws and BWs. The conceptual hydrogeologic model supported by isotopic data indicated that groundwater recharge was from the main Mendoza/Tunuyan Rivers in remote areas and that local rainwater recharge is negligible. The isotopic data suggests that a faster groundwater flow recharge could occur without any influence of a previous evaporation process. The natural As background level was 104 mu g/L, with a range of between 8.6 and 394 mu g/L. The average As concentration in Ws was 114 mu g/L. Water from BWs showed higher average As concentration of 235 mu g/L with a higher dispersion, high HCO3-, NO3- PO4-3 and Cl- concentrations, and the lowest concentrations of O-2 with greater turbidity than groundwater from Ws. The increase in As concentrations in groundwater of NE Mendoza is not related to evaporation processes despite arid climatic conditions. According to the oxidizing environment in the aquifer, high pH and very fine sediments, adsorption-desorption processes from solid surfaces were the determining factors for the availability and spatial variability of As in groundwater. Spatial variability was related to type of well rather than to geomorphologic units or to flow direction. The design of bucket wells, near corrals, allows the input of windblown sediments and leachate from livestock units creating point sources of As contamination in water used for human consumption.
D'Angelo, JA ;REVIEW OF PALAEOBOTANY AND PALYNOLOGY ,2019 ,268 ,109 -124 .
Cuticles of compression-preserved Dicroidium odontopteroides and Johnstonia coriacea (Corystospermaceae, Upper Triassic, Mendoza, Argentina) are spectrochemically analyzed. The objectives included (i) studying the chemical resistance of cuticles to different oxidative conditions to gain new insights into their fine molecular structure and its likely (ii) chemotaxonomical and (iii) paleoecophysiological implications. Two experimental procedures are employed to obtain the cuticles from the compressions: (a) room-temperature (25 degrees C and up to 75 min) and (b) high-temperature (500 degrees C and up to 50 min) oxidative reactions using Schulze's reagent. Details of the molecular structure (i.e., functional groups) of cuticles are studied using Fourier transform infrared (FTIR) spectroscopy followed by data evaluation using principal component analysis and one-way ANOVA test. Morphological changes as a function of different oxidative conditions are monitored by scanning electron microscopy. Results indicate that the geomacropolymers composing the cuticles of both taxa are chemically characterized by high contents of aliphatic compounds with relatively smaller amounts of aromatic hydrocarbons. The presence of considerable contents of carbonyl groups in the cuticles indicates likely ester chemical "bridges" that cross-link aliphatic and aromatic hydrocarbons. These chemical bonds "strengthen" the molecular structure, thus increasing the overall mechanical and chemical resistance of the cuticle. Conclusions include: (i) the cuticles of both taxa are extraordinarily resistant to extremely harsh chemical conditions, which modified neither morphology nor chemical structure; (ii) independently of the oxidative procedure employed, the two taxa cannot be statistically differentiated using the cuticular FTIR information; (iii) the high chemical resistance of the studied cuticles represents likely ecophysiological adaptations of the once living plants to survive stressful environmental conditions. They could have included high temperatures, elevated CO2 concentrations, seasonal drought, and nutrient-deficient, acidic soils exposed to intensive solar irradiation, and eventual acid (H2SO4) precipitations. Chemical results are in agreement with taphonomic, sedimentological, paleopedological and (micro- and macro-) morphological data, which indicate that the studied plants were likely opportunistic and stress-tolerant colonizers that dominated flood-disturbed, waterlogged lowlands.
Rodriguez, CY ;Bustos, DA ; Sanabria, EA ; PHYSIOLOGICAL AND BIOCHEMICAL ZOOLOGY ,2019 ,92 ,473 -480 .
We studied the role of plasma glucose concentration on individuals of Rhinella spinulosa in response to annual temperature variation and freezing temperatures. Measurements and collection of toads were made every 2 mo for a period of 1 yr. To determine whether toads were exposed to low temperatures in their habitat, we proceeded with the study of operating temperatures (T (e)). The measures of operating temperature were determined by using plaster models placed in the field, simulating the situation where toads are outside or inside shelters, for which it was determined that individuals in the winter season would have been exposed to temperatures below 0 degrees C. Glucose levels measured in field specimens showed an annual variation, but laboratory specimens exposed to freezing temperatures had higher plasma glucose levels than field toads. Furthermore, the crystallization temperature for the species has been recorded at -1.6 degrees C. The increase in glucose concentration indicates its possible use as a cryoprotectant before freezing events in this species of frogs and also in the coldest months at temperatures below 0 degrees C.
Bustamante, CM ;Ramirez, FF ; Sanchez, CG ; Scherlis, DA ; JOURNAL OF CHEMICAL PHYSICS ,2019 ,151 ,-.
Molecular simulations of transport dynamics in nanostructures usually require the implementation of open quantum boundary conditions. This can be instrumented in different frameworks including Green's functions, absorbing potentials, or the driven Liouville von Neumann equation, among others. In any case, the application of these approaches involves the use of large electrodes that introduce a high computational demand when dealing with first-principles calculations. Here, we propose a hybrid scheme where the electrodes are described at a semiempirical, tight binding level, coupled to a molecule or device represented with density functional theory (DFT). This strategy allows us to use massive electrodes at a negligible computational cost, preserving the accuracy of the DFT method in the modeling of the transport properties, provided that the electronic structure of every lead is properly defined to behave as a conducting fermionic reservoir. We study the nature of the multiscale coupling and validate the methodology through the computation of the tunneling decay constant in polyacetylene and of quantum interference effects in an aromatic ring. The present implementation is applied both in microcanonical and grand-canonical frameworks, in the last case using the Driven Liouville von Neumann equation, discussing the advantages of one or the other. Finally, this multiscale scheme is employed to investigate the role of an electric field applied normally to transport in the conductance of polyacetylene. It is shown that the magnitude and the incidence angle of the applied field have a considerable effect on the electron flow, hence constituting an interesting tool for current control in nanocircuits. Published under license by AIP Publishing.
Garcia, AM ;Moguilner, S ; Torquati, K ; Garcia-Marco, E ; Herrera, E ; Munoz, E ; Castillo, EM ; Kleineschay, T ; Sedeno, L ; Ibanez, A ; NEUROIMAGE ,2019 ,197 ,439 -449 .
Research on how the brain construes meaning during language use has prompted two conflicting accounts. According to the 'grounded view', word understanding involves quick reactivations of sensorimotor (embodied) experiences evoked by the stimuli, with simultaneous or later engagement of multimodal (conceptual) systems integrating information from various sensory streams. Contrariwise, for the 'symbolic view', this capacity depends crucially on multimodal operations, with embodied systems playing epiphenomenal roles after comprehension. To test these contradictory hypotheses, the present magnetoencephalography study assessed implicit semantic access to grammatically constrained action and non-action verbs (n =100 per category) while measuring spatiotemporally precise signals from the primary motor cortex (M1, a core region subserving bodily movements) and the anterior temporal lobe (ATL, a putative multimodal semantic hub). Convergent evidence from sensor- and source-level analyses revealed that increased modulations for action verbs occurred earlier in M1 (similar to 130-190 ms) than in specific ATL hubs (similar to 250-410 ms). Moreover, machine-learning decoding showed that trial-by-trial classification peaks emerged faster in M1 (similar to 100-175 ms) than in the ATL (similar to 345-500 ms), with over 71% accuracy in both cases. Considering their latencies, these results challenge the 'symbolic view' and its implication that sensorimotor mechanisms play only secondary roles in semantic processing. Instead, our findings support the 'grounded view', showing that early semantic effects are critically driven by embodied reactivations and that these cannot be reduced to post-comprehension epiphenomena, even when words are individually classified. Briefly, our study offers non-trivial insights to constrain fine-grained models of language and understand how meaning unfolds in neural time.
Canizo, BV ;Agostini, E ; Oller, ALW ; Dotto, GL ; Vega, IA ; Escudero, LB ; WATER AIR AND SOIL POLLUTION ,2019 ,230 ,-.
It was investigated the potential of Rhodococcus erythropolis AW3 as a biosorbent for the removal of crystal violet (CV) dye from natural water and real effluents. The biosorbent was characterized by flow cytometry, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy X-ray dispersive spectroscopy (EDS), and point of zero charge (pH(ZPC)). Batch biosorption experiments were performed to optimize different parameters involved in the biosorption process. The equilibrium was reached at 90 min at the optimum biosorbent dose of 0.50 g L-1 and pH of 9.0. Results indicated that Langmuir isotherm model was the most suitable to represent the experimental data, and the highest biosorption capacity was 289.8 mg g(-1). Kinetic data were well fitted with the pseudo-second-order model. The thermodynamic study showed that the process was favorable, exothermic, and associated with an increase of entropy. Finally, it was demonstrated that the biosorption process using Rhodococcus erythropolis AW3 could be successfully applied to remove CV from natural water and effluents derived from clinical and industrial activities.
Fernandez, RP ;Carmona-Balea, A ; Cuevas, CA ; Barrera, JA ; Kinnison, DE ; Lamarque, JF ; Blaszczak-Boxe, C ; Kim, K ; Choi, W ; Hay, T ; Blechschmidt, AM ; Schonhardt, A ; Burrows, JP ; Saiz-Lopez, A ; JOURNAL OF ADVANCES IN MODELING EARTH SYSTEMS ,2019 ,11 ,2259 -2289 .
Current chemistry climate models do not include polar emissions and chemistry of halogens. This work presents the first implementation of an interactive polar module into the very short-lived (VSL) halogen version of the Community Atmosphere Model with Chemistry (CAM-Chem) model. The polar module includes photochemical release of molecular bromine, chlorine, and interhalogens from the sea-ice surface, and brine diffusion of iodine biologically produced underneath and within porous sea-ice. It also includes heterogeneous recycling of inorganic halogen reservoirs deposited over fresh sea-ice surfaces and snow-covered regions. The polar emission of chlorine, bromine, and iodine reach approximately 32, 250, and 39 Gg/year for Antarctica and 33, 271, and 4 Gg/year for the Arctic, respectively, with a marked seasonal cycle mainly driven by sunlight and sea-ice coverage. Model results are validated against polar boundary layer measurements of ClO, BrO, and IO, and satellite BrO and IO columns. This validation includes satellite observations of IO over inner Antarctica for which an iodine "leapfrog" mechanism is proposed to transport active iodine from coastal source regions to the interior of the continent. The modeled chlorine and bromine polar sources represent up to 45% and 80% of the global biogenic VSLCl and VSLBr emissions, respectively, while the Antarctic sea-ice iodine flux is similar to 10 times larger than that from the Southern Ocean. We present the first estimate of the contribution of polar halogen emissions to the global tropospheric halogen budget. CAM-Chem includes now a complete representation of halogen sources and chemistry from pole-to-pole and from the Earth's surface up to the stratopause.
Roldan, JS ;Candurra, WA ; Colombo, MI ; Delgui, LR ; JOURNAL OF VIROLOGY ,2019 ,93 ,-.
Junin virus (JUNV), a member of the family Arenaviridae, is the etiological agent of Argentine hemorrhagic fever (AHF), a potentially deadly endemicepidemic disease affecting the population of the most fertile farming land of Argentina. Autophagy is a degradative process with a crucial antiviral role; however, several viruses subvert the pathway to their benefit. We determined the role of autophagy in JUNV-infected cells by analyzing LC3, a cytoplasmic protein (LC3-I) that becomes vesicle membrane associated (LC3-II) upon induction of autophagy. Cells overexpressing enhanced green fluorescent protein (EGFP)-LC3 and infected with JUNV showed an increased number of LC3 punctate structures, similar to those obtained after starvation or bafilomycin A1 treatment, which leads to autophagosome induction or accumulation, respectively. We also monitored the conversion of LC3-I to LC3-II, observing LC3-II levels in JUNV-infected cells similar to those observed in starved cells. Additionally, we kinetically studied the number of LC3 dots after JUNV infection and found that the virus activated the pathway as early as 2 h postinfection (p.i.), whereas the UV-inactivated virus did not induce the pathway. Cells subjected to starvation or pretreated with rapamycin, a pharmacological autophagy inductor, enhanced virus yield. Also, we assayed the replication capacity of JUNV in Atg5 knockout or Beclin 1 knockdown cells (both critical components of the autophagic pathway) and found a significant decrease in JUNV replication. Taken together, our results constitute the first study indicating that JUNV infection induces an autophagic response, which is functionally required by the virus for efficient propagation.
Gandini, CL ;Garcia, LE ; Abbona, CC ; Sanchez-Puerta, MV ; MOLECULAR PHYLOGENETICS AND EVOLUTION ,2019 ,137 ,274 -284 .
Short repeats (SR) play an important role in shaping seed plant mitochondrial genomes (mtDNAs). However, their origin, distribution, and relationships across the different plant lineages remain unresolved. We focus on the angiosperm family Solanaceae that shows great variation in repeat content and extend the study to a wide diversity of seed plants. We determined the complete nucleotide sequences of the organellar genomes of the medicinal plant Physochlaina orientalis (Solanaceae), member of the tribe Hyoscyameae. To understand the evolution of the P. orientalis mtDNA we made comparisons with those of five other Solanaceae. P. orientalis mtDNA presents the largest mitogenome (similar to 685 kb in size) among the Solanaceae and has an unprecedented 8-copy repeat family of similar to 8.2 kb in length and a great number of SR arranged in tandem-like structures. We found that the SR in the Solanaceae share a common origin, but these only expanded in members of the tribe Hyoscyameae. We discuss a mechanism that could explain SR formation and expansion in P. orientalis and Hyoscyamus niger. Finally, the great increase in plant mitochondrial data allowed us to systematically extend our repeat analysis to a total of 136 seed plants to characterize and analyze for the first time families of SR among seed plant mtDNAs.
Maldonado, MB ;Aranibar, JN ; Serranoa, AM ; Chacoff, NP ; Vazquez, DP ; CATENA ,2019 ,179 ,66 -73 .
Insects are involved in the biogeochemical cycles of multiple elements and influence soil fertility. In particular, soil insects and the functions that they support can affect the response of terrestrial ecosystems to environmental changes. We experimentally studied the role of dung beetles as recyclers of cow dung in drylands of the Central Monte in mid-western Argentina; and we extrapolated these results to ecosystem impact in a grazing field, considering the dung beetle's abundance in summer. We conducted experiments with four species of dung beetles (Sulcophanaeus imperator, Eucranium arachnoides, Digitonthophagus gazelle and Malagoniella puncticollis), and quantified their abundance on the field. Dung beetles incorporated nitrogen, ammonium, and phosphorous to the soil, but this activity varied substantially among species. The highest quantity of organic matter, nitrogen and phosphate was incorporated to the soil by S. imperator, one of the larger beetle studied. While the per capita effect of S. imperator is superior to other species studied, the impact on the ecosystem of the invasive D. gazelle might be superior due to their major abundance in grazing fields. Our results highlight the importance of considering both components, per capita effect and abundance, to estimate with more reliability the relative importance of dung beetle species. Given that the effect of dung beetles on nutrient cycling is variable among species, and their abundance is variable in space, it is important to conserve beetle diversity in order to maximize their beneficial impacts on soils. Therefore, dung beetle effect on soil might be crucial in drylands to mitigate the nitrogen losses caused by grazing.
Rodriguez, C ;Prieto, GI ; Vega, IA ; Castro-Vazquez, A ; PEERJ ,2019 ,7 ,-.
Ampullariids are freshwater gastropods bearing a gill and a lung, thus showing different degrees of amphibiousness. In particular, Pomacea canaliculata (Caenogastropoda, Ampullariidae) is an obligate air-breather that relies mainly or solely on the lung for dwelling in poorly oxygenated water, for avoiding predators, while burying in the mud during aestivation, and for oviposition above water level. In this paper, we studied the morphological peculiarities of the gill in this species. We found (1) the gill and lung vasculature and innervation are intimately related, allowing alternation between water and air respiration; (2) the gill epithelium has features typical of a transporting rather than a respiratory epithelium; and (3) the gill has resident granulocytes within intraepithelial spaces that may serve a role for immune defence. Thus, the role in oxygen uptake may be less significant than the roles in ionic/osmotic regulation and immunity. Also, our results provide a morphological background to understand the dependence on aerial respiration of Pomacea canaliculata. Finally, we consider these findings from a functional perspective in the light of the evolution of amphibiousness in the Ampullariidae, and discuss that master regulators may explain the phenotypic convergence of gill structures amongst this molluscan species and those in other phyla.
Mangiarotti, A ;Galassi, VV ; Puentes, EN ; Oliveira, RG ; Del Popolo, MG ; Wilke, N ; LANGMUIR ,2019 ,35 ,9848 -9857 .
Hopanoids are pentacyclic molecules present in membranes from some bacteria, recently proposed as sterol surrogates in these organisms. Diplopterol is an abundant hopanoid that, similar to sterols, does not self-aggregate in lamellar structures when pure, but forms monolayers at the air-water interface. Here, we analyze the interfacial behavior of pure diplopterol and compare it with sterols from different organisms: cholesterol from mammals, ergosterol from fungi, and stigmasterol from plants. We prepared Langmuir monolayers of the compounds and studied their surface properties using different experimental approaches and molecular dynamics simulations. Our results indicate that the films formed by diplopterol, despite being compact with low mean molecular areas, high surface potentials, and high refractive index, depict shear viscosity values similar to that for fluid films. Altogether, our results reveal that hopanoids have similar interfacial behavior than that of sterols, and thus they may have the capacity of modulating bacterial membrane properties in a similar way sterols do in eukaryotes.
Planes, MB ;Millan, EN ; Urbassek, HM ; Bringa, EM ; MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY ,2019 ,487 ,L13 -L17 .
Using granular mechanics, we determine the stopping force acting on spherical granular projectiles impinging on a flat granular bed. We find that the stopping force is proportional to the impact energy, as in Poncelet's law. For fixed velocity, it is proportional to the projectile cross-sectional area rather than to its volume. These dependences only hold in the early stages of stopping, before the projectile has been strongly fragmented. Analogies to the stopping of atomic clusters in compact matter are pointed out.
Zarco, A ;Cueto, VR ; Sagario, MC ; Marone, L ; CANADIAN JOURNAL OF ZOOLOGY ,2019 ,97 ,606 -611 .
Animal populations often decline due to habitat disturbance, but the initial response of organisms to human-induced environmental change is usually behavioral. Intra-and inter-specific interactions can restrict or facilitate access to resources, resulting in changes to individual fitness, and resource depletion may affect the frequency and strength of interactions. In birds, it is often assumed that feeding in groups increases foraging efficiency. We assessed how the reduction of seed resources provoked by cattle grazing affected different properties of seed-eating bird flocks in woodlands having the same structural characteristics but differing in seed abundance. Under lower availability of grass seeds (i.e., under grazing), flocks were smaller and less rich and birds showed a lower flocking propensity. This pattern could be explained by three non-exclusive hypotheses. Food reduction caused by grazing (i) decreases the number of seed-eating birds and concomitantly generates smaller flocks; (ii) reduces the density of nuclear species, decreasing the group cohesion in large flocks; (iii) makes large flocks less attractive by increasing individual competence for food. Our results provide evidence that cattle grazing affect the interactions of seed-eating birds and suggest the importance of understanding flocking behavior to bring about management actions.
Canizo, BV ;Escudero, LB ; Pellerano, RG ; Wuilloud, RG ; COMPUTERS AND ELECTRONICS IN AGRICULTURE ,2019 ,162 ,514 -522 .
The knowledge of wine origin is an important aspect in winemaking industries due to the Denomination of Controlled Origin. In this work, a data mining algorithms comparison study of grape-skin samples from five regions of Mendoza, Argentina, and builds classification models capable of predicting provenance based on multi-elemental composition, were developed. Inductively coupled plasma mass spectrometry (ICP-MS) was used to determine 29 elements (Ag, As, Ce, Co, Cs, Cu, Eu, Fe, Ga, Gd, La, Lu, Mn, Mo, Nb, Nd, Ni, Pr, Rb, Sm, Te, Ti, Tl, Tm, U, V, Y, Zn and Zr). Four classification techniques, including multinomial logistic regression (MLR), k-nearest neighbors (k-NN), support vector machines (SVM), and random forests (RF) were assessed. The best results were achieved for SVM and RF models, with 84% and 88.9% prediction accuracy, respectively, on the 10 fold cross validation. The RF variable importance showed that Rb (rubidium) was the most relevant components for prediction.
Garcia, LE ;Zubko, MK ; Zubko, EI ; Sanchez-Puerta, MV ; PLANT MOLECULAR BIOLOGY ,2019 ,100 ,433 -450 .
Key messageCybrid plant mitochondria undergo homologous recombination, mainly BIR, keep a single allele for each gene, and maintain exclusive sequences of each parent and a single copy of the homologous regions.AbstractThe maintenance of a dynamic equilibrium between the mitochondrial and nuclear genomes requires continuous communication and a high level of compatibility between them, so that alterations in one genetic compartment need adjustments in the other. The co-evolution of nuclear and mitochondrial genomes has been poorly studied, even though the consequences and effects of this interaction are highly relevant for human health, as well as for crop improvement programs and for genetic engineering. The mitochondria of plants represent an excellent system to understand the mechanisms of genomic rearrangements, chimeric gene formation, incompatibility between nucleus and cytoplasm, and horizontal gene transfer. We carried out detailed analyses of the mtDNA of a repeated cybrid between the solanaceae Nicotiana tabacum and Hyoscyamus niger. The mtDNA of the cybrid was intermediate between the size of theparental mtDNAs and the sum of them. Noticeably, most of the homologous sequences inherited from both parents were lost. In contrast, the majority of the sequences exclusive of a single parent were maintained. The mitochondrial gene content included a majority of N. tabacum derived genes, but also chimeric, two-parent derived, and H. niger-derived genes in a tobacco nuclear background. Any of these alterations in the gene content could be the cause of CMS in the cybrid. The parental mtDNAs interacted through 28 homologous recombination events and a single case of illegitimate recombination. Three main homologous recombination mechanisms were recognized in the cybrid mitochondria. Break induced replication (BIR) pathway was the most frequent. We propose that BIR could be one of the mechanisms responsible for the loss of the majority of the repeated regions derived from H. niger.
de la Fuente, A ;Sedeno, L ; Vignaga, SS ; Ellmann, C ; Sonzogni, S ; Belluscio, L ; Garcia-Cordero, I ; Castagnaro, E ; Boano, M ; Cetkovich, M ; Torralva, T ; Canepa, ET ; Tagliazucchi, E ; Garcia, AM ; Ibanez, A ; NEUROPSYCHOPHARMACOLOGY ,2019 ,44 ,1425 -1434 .
Contemporary neurocognitive models of drug addiction have associated this condition with changes in interoception - namely, the sensing and processing of body signals that fulfill homeostatic functions relevant for the onset and maintenance of addictive behavior. However, most previous evidence is inconsistent, behaviorally unspecific, and virtually null in terms of direct electrophysiological and multimodal markers. To circumvent these limitations, we conducted the first assessment of the relation between cardiac interoception and smoked cocaine dependence (SCD) in a sample of (a) 25 participants who fulfilled criteria for dependence on such a drug, (b) 22 participants addicted to insufflated clorhidrate cocaine (only for behavioral assessment), and (c) 25 healthy controls matched by age, gender, education, and socioeconomic status. We use a validated heartbeat-detection (HBD) task and measured modulations of the heart-evoked potential (HEP) during interoceptive accuracy and interoceptive learning conditions. We complemented this behavioral and electrophysiological data with offline structural (MRI) and functional connectivity (fMRI) analysis of the main interoceptive hubs. HBD and HEP results convergently showed that SCD subjects presented ongoing psychophysiological measures of enhanced interoceptive accuracy. This pattern was associated with a structural and functional tuning of interoceptive networks (reduced volume and specialized network segregation). Taken together, our findings provide the first evidence of an association between cardiac interoception and smoked cocaine, partially supporting models that propose hyper-interoception as a key aspect of addiction. More generally, our study shows that multimodal assessments of interoception could substantially inform the clinical and neurocognitive characterization of psychophysiological and neurocognitive adaptations triggered by addiction.
Stocco, AF ;Diaz, ME ; Romera, MCR ; Mercado, LA ; Rivero, ML ; Ponsone, ML ; BIOLOGICAL CONTROL ,2019 ,134 ,114 -122 .
Postharvest diseases cause considerable loss of fruit during transportation and storage. Synthetic fungicides are primarily used to control them. However, the recent trend is to shift toward safer and more eco-friendly alternatives for the control of postharvest decays. In Argentina, Alternaria genus was cited as a postharvest pathogen on table grapes for the first time during 2010-2012 seasons. The aim of this study was to identify, by morphological and molecular techniques, Alternaria spp. strains isolated from table grapes cv. Red Globe in different phenological stages of vine and postharvest storage in Mendoza province. In addition, we intended to propose an alternative postharvest management to the use of sulfur dioxide (SO2) generators (traditional method). We searched for a lower environmental impacting substitute using the yeast strain Metschnikowia pulcherrima RCM2 and chitosan coatings as possible control agents. The results showed that the pathogen was present in all the stages studied and the 100% of the strains belonged to the species-group Alternaria alternata. Besides, chitosan coatings showed to be a good alternative method to SO2 generators. This work is focus on the study of the incidence of Alternaria spp. during the phenological cycle and postharvest storage of table grapes cv. Red Globe, and also on the evaluation of alternative strategies to the use of SO2 for the control of this disease during the extended cold storage.
Bessega, C ;Cony, M ; Saidman, BO ; Aguilo, R ; Villagra, P ; Alvarez, JA ; Pometti, C ; Vilardi, JC ; FOREST ECOLOGY AND MANAGEMENT ,2019 ,443 ,59 -68 .
Ecosystem restoration has gained increasing interest to mitigate the effects of climate change, loss of biodiversity and desertification. Since the genetic composition of the reproductive material to revegetate degraded areas affects the success of restoration throughout time, information on the genetic properties of possible seed sources is essential to evaluate the risks associated to management practices. Prosopis flexuosa (Leguminosae) is an important native species in Argentina valuable from an economic and ecological point of view. Aiming to give restoration recommendations for the use of this species for rapid recuperation of the plant cover in arid regions of Monte desert, our goals were to quantify the genetic basis of phenotypic differences in height and basal diameter and the genetic differentiation of neutral markers among several provenances installed in a provenance and progeny test. Ours results suggest that the morphological variation have a significant genetic basis and differences among provenances may be explained by local adaptation. Low but significant genetic differentiation was detected by microsatellites among provenances. From our results the recommendation to provide a broad genetic basis in a restoration programme is obtaining seeds representing all genetic clusters identified, rather than all provenances. This implies avoiding sampling of more than one provenance embracing the same genetic clusters. If the priority of the programme is reaching ground cover rapidly the representation of different clusters in the source sample may be adjusted according to a tradeoff between expected gain in growth rate while keeping a broad genetic basis that insures evolutionary resilience.
Fengler, E ;Totz, JF ; Kaluza, P ; Engel, H ; CHAOS ,2019 ,29 ,-.
We present an adaptive control scheme that realizes desired dynamics of an oscillator network with a given number of communities by adjusting the coupling weights between oscillators accordingly. The scheme allows, for example, to simultaneously establish different pregiven synchronization levels in the particular communities as well as phase relationships between them. We apply the method in numerical simulations with all-to-all and randomly coupled networks. Moreover, we provide an experimental proof of concept validating our numerical findings in a network of optically coupled photosensitive chemical micro-oscillators. Published under license by AIP Publishing.
Orosco, RP ;Ojeda, MW ; Gonzalez, JA ; Barbosa, LI ; SILICON ,2019 ,11 ,1413 -1419 .
A novel pyrometallurgical process for the synthesis of porous forsterite by calcination in chlorine of a mixture containing hydromagnesite and silica gel was developed. The aim of this work was to produce porous forsterite at low temperatures and short reaction times. Effects of temperature, reaction time and chlorine on the synthesis reaction were studied. Also, the reaction mechanism involved in the process was investigated. Isothermal and non-isothermal chlorination assays were carried out in a thermogravimetric equipment designed to work in corrosive atmospheres. Reagents and products were analyzed by thermogravimetry (TG) and X-ray diffraction (XRD), scanning electron microscopy (SEM) and N-2 adsorption-desorption isotherm (BET). The results showed that forsterite was obtained at 700 degrees C with a mesoporous structure and a specific surface area of 16.8 m(2)/g. Furthermore, it was observed that the presence of chlorine favored the decomposition of hydromagnesite.
Dellagnola, FA ;Montes, MM ; Martorelli, SR ; Vega, IA ; PARASITOLOGY ,2019 ,146 ,839 -848 .
In the context of a broader program dealing with the symbiotic associations of apple snails, we sampled three species that coexist in Lake Regatas (Palermo, Buenos Aires, Argentina). The population of Asolene platae, (but not those of Pomacea canaliculata and Pomacea scalaris) showed trematode larvae (echinocercariae and xiphidiocercariae) in haemocoelic spaces and connective tissue of the digestive gland. The echinocercariae resembled those of the genus Echinochasmus, but lacked sensory hairs on their body and tail; whereas xiphidiocercariae were similar to the xiphidiocercariae armatae belonging to the Opisthoglyphe type. The phylogenetical positions of these trematodes were inferred by the 28S rRNA, ITS1 and mtCOXI gene sequences. The 28S rRNA gene linked the echinocercarial sequences with the polyphyletic genus Echinochasmus (Echinochasmidae), while the xiphidiocercarial sequences were linked with the genus Phaneropsolus (Phaneropsolidae). The molecular markers used were able to distinguish two cryptic molecular entities of the single echinocercarial morphotype. Although ITS1 and mtCOXI did not allow resolving phylogeny beyond the family level because of the scarce number of sequences in the molecular databases, both cercariae (echinocercariae and xiphidiocercariae) could be distinguished by the Internal Transcribed Spacer 1 amplicon size. This is the first correlative morphological and molecular study of zoonotic trematodes in Neotropical ampullariids.
Pereyra, M ;Pol, RG ; Galetto, L ; AUSTRAL ECOLOGY ,2019 ,44 ,668 -679 .
The Chaco is the largest dry forest biome in South America and one of the regions most threatened by agricultural intensification. As a consequence, in several areas Chaco forests persist as forest remnants of different sizes embedded in an agricultural matrix. Ants are social insects that have key roles in ecosystem functioning, and the effects of this ongoing land use change process on ant communities are little known for this region. In the present study, we assessed the consequences of land use replacement by monocultures and forest fragmentation on ant communities. Particularly, we assessed whether patch size, patch isolation and edge effect affect species richness and composition of ground-dwelling ants in fragmented landscapes of Chaco forests. We collected ants by combining hand collecting and pitfall traps in 17 forest fragments and the surrounding matrix from two sites in Cordoba, Argentina. Patch size and patch isolation had no effect on ant richness; however, patch isolation and, to a lesser extent, patch size altered ant species composition. The ant community was not affected by edge but it was negatively affected by the crop matrix, which reduced richness and altered species composition. These results indicate that monoculture matrices severely affect ant communities in the Chaco forests, and that the effects of other indicators of habitat fragmentation (patch size and edge effect) are subtler and less relevant. In the present context of land use change, even small fragments could have an important value for the conservation of ant diversity.
Marquez, O ;Simondi, S ; Vargas, JA ; REVISTA DE LA UNION MATEMATICA ARGENTINA ,2019 ,60 ,45 -59 .
For a connected, noncompact simple matrix Lie group G so that a maximal compact subgroup K has a three dimensional simple ideal, in this note we analyze the admissibility of the restriction of irreducible square integrable representations for the ambient group when they are restricted to certain subgroups that contain the three dimensional ideal. In this setting we provide a formula for the multiplicity of the irreducible factors. Also, for general G such that G/K is an Hermitian G-manifold we give a necessary and sufficient condition so that an arbitrary square integrable representation of the ambient group is admissible over the semisimple factor of K.
Guida-Johnson, B ;Zuleta, GA ; WETLANDS ECOLOGY AND MANAGEMENT ,2019 ,27 ,243 -256 .
The growth of human societies worldwide has been associated with the degradation of natural resources; in particular, freshwater ecosystems are among the most seriously threatened. Riparian restoration has received much attention due to the importance of ecological functions and ecosystem services sustained by watercourses. The objective of this paper was to assess the environmental quality of riversides in a highly urbanized watershed in the Buenos Aires metropolitan area (Argentina) in order to identify rehabilitation opportunities. We conducted a stratified random sampling of 82 sites where we recorded 33 variables regarding geomorphologic traits, vegetation attributes and anthropogenic impacts. Pristine riparian habitats are almost completely extirpated throughout the watershed and most of the streams sampled showed signs of degradation related to multiple threats. We detected a degradation pattern that follows the urban-rural gradient occurring in the watershed which enabled the definition of four types of riversides. In order to identify potential river rehabilitation alternatives in accordance with each degradation driver detected, we performed a systematic review of the literature. We identified the fluvial rehabilitation techniques implemented and we grouped them into four types of measures: passive restoration, active abiotic techniques, active biotic techniques and active social techniques. We also recognized the reported social, ecological, economic and/or political constraints which were encountered in those experiences. All possible dimensions of the potential constraints should be recognized during the planning stage of rehabilitation and then properly addressed before and during the implementation of measures in order to make the interventions successful.
Ibiricu, LM ;Casal, GA ; Martinez, RD ; Luna, M ; Canale, JI ; Alvarez, BN ; Riga, BG ; CRETACEOUS RESEARCH ,2019 ,98 ,276 -291 .
A new ornithopod dinosaur, the medium-sized Sektensaurus sanjuanboscoi gen. et sp nov. from the Coniacian-Maastricthian strata of the Lago Colhue-Huapi Formation, Golfo San Jorge Basin, Patagonia, is here described. The specimen consists of disarticulated postcranial bones belonging to a single individual. It is diagnosed by an unique association of five autapomorphies on the dorsal and sacral vertebrae and the humerus. A cladistics analysis indicates that Sektensaurus was an iguanodontian ornithopod which inhabited Patagonia during the Late Cretaceous. Likewise, Sektensaurus is the first nonhadrosaurid, probably elasmarian, ornithopod recorded from the uppermost Cretaceous of central Patagonia. In a broad context, this discovery increases the anatomical knowledge of ornithopods and adds new data on the composition of dinosaur faunas that lived in Patagonia close to the Antarctica, at the end of the Cretaceous. (C) 2019 Elsevier Ltd. All rights reserved.
Fiorentini, EF ;Canizo, BV ; Wuilloud, RG ; TALANTA ,2019 ,198 ,146 -153 .
A dispersive liquid-liquid microextraction (DLLME) method was developed based on the application of a magnetic ionic liquid (MIL) used as extractant phase for trace As determination in honey samples by electrothermal atomic absorption spectrometry (ETAAS). The procedure was simple, efficient and did not require a centrifugation stage. The As(III) species was preconcentrated by chelation with ammonium diethyldithiophosphate under acidic conditions at 3 mol L-1 HCl, followed by the extraction of the chelated analyte with the MIL trihexyl(tetradecyl)phosphonium tetrachloroferrate (III) ([P-6,P-6,P-6,P-14]FeCl4) and acetonitrile as dispersant. The MIL phase containing the analyte was separated simply by a magnet. The collected aliquot of the MIL phase was injected directly into the graphite furnace of ETAAS for As determination. Under optimal experimental conditions, an extraction efficiency of 99% and a sensitivity enhancement factor of 110 were obtained. The limit of detection was 12 ng L-1 As and the relative standard deviation 3.9% (at 1 mu g L-1 As and n = 10), calculated from the peak height of the absorbance signals. The linear range obtained was 0.02-5.0 mu g L-1. This work reports the first application of the MIL [P-6,P-6,P-6,P-14]FeCl4 along with the DLLME technique for the determination of As in honeys.
Ramirez, F ;Dundas, D ; Sanchez, CG ; Scherlis, DA ; Todorov, TN ; JOURNAL OF PHYSICAL CHEMISTRY C ,2019 ,123 ,12542 -12555 .
The so-called driven Liouville von Neumann equation is a dynamical formulation to simulate a voltage bias across a molecular system and to model a time-dependent current in a grand-canonical framework. This approach introduces a damping term in the equation of motion that drives the charge to a reference, out of equilibrium density. Originally proposed by Horsfield and coworkers, further work on this scheme has led to different coexisting versions of this equation. On the other hand, the multiple-probe scheme devised by Todorov and collaborators, known as the hairy-probes method, is a formal treatment based on Green's functions that allows the electrochemical potentials in two regions of an open quantum system to be fixed. In this article, the equations of motion of the hairy-probes formalism are rewritten to show that, under certain conditions, they can assume the same algebraic structure as the driven Liouville-von Neumann equation in the form proposed by Morzan et al. (J. Chem. Phys. 2017, 146, 044110). In this way, a new formal ground is provided for the latter, identifying the origin of every term. The performances of the different methods are explored using tight-binding time-dependent simulations in three trial structures, designated as ballistic, disordered, and resonant models. In the context of first-principles Hamiltonians, the driven Liouville von Neumann approach is of special interest, because it does not require the calculation of Green's functions. Hence, the effects of replacing the reference density based on the Green's function by one obtained from an applied field are investigated, to gain a deeper understanding of the limitations and the range of applicability of the driven Liouville-von Neumann equation.
Douglas-Gallardo, OA ;Berdakin, M ; Frauenheim, T ; Sanchez, CG ; NANOSCALE ,2019 ,11 ,8604 -8615 .
In the last thirty years, the study of plasmonic properties of noble metal nanostructures has become a very dynamic research area. The design and manipulation of matter in the nanometric scale demands a deep understanding of the underlying physico-chemical processes that operate in this size regimen. Here, a fully atomistic study of the spectroscopic and photodynamic properties of different icosahedral silver and gold nanoclusters has been carried out by using a Time-Dependent Density Functional Tight-Binding (TD-DFTB) model. The optical absorption spectra of different icosahedral silver and gold nanoclusters of diameters between 1 and 4 nanometers have been simulated. Furthermore, the energy absorption process has been quantified by means of calculating a fully quantum absorption cross-section using the information contained in the reduced single-electron density matrix. This approach allows us take into account the quantum confinement effects dominating in this size regime. Likewise, the plasmon-induced hot-carrier generation process under laser illumination has been explored from a fully dynamical perspective. We have found noticeable differences in the energy absorption mechanisms and the plasmon-induced hot-carrier generation process in both metals which can be explained by their respective electronic structures. These differences can be attributed to the existence of ultra-fast electronic dissipation channels in gold nanoclusters that are absent in silver nanoclusters. To the best of our knowledge, this is the first report that addresses this topic from a real time fully atomistic time-dependent approach.
Pinna, EG ;Martinez, AA ; Tunez, FM ; Drajlin, DS ; Rodriguez, MH ; REVISTA MEXICANA DE INGENIERIA QUIMICA ,2019 ,18 ,441 -449 .
This work shows the results of a comparative hydrometallurgical study of LiCoO2 leaching, obtained from the cathodes of spent lithium-ion batteries (LIBs), with HF and HF/H2O2. The operational parameters researched were H2O2 and HF concentrations, solid-liquid ratio, stirring speed, temperature and reaction time. The experimental results indicated that the best working conditions, with dissolution values close to 100%, were 348 K, 330 rpm, 30 min, 8 g/L, HF 0.6 M and H2O2 0.7 M. Thermodynamic study of the dissociation of HF in aqueous solution and E-H-pH diagrams for Li-H2O, Co-H2O and Li-Co-F-H2O systems were performed. The results showed the feasibility of extracting and recovering metals contained in the sample.
Adessi, TG ;Borioni, JL ; Pigni, NB ; Bastida, J ; Cavallaro, V ; Murray, AP ; Puiatti, M ; Oberti, JC ; Leiva, S ; Nicotra, VE ; Garcia, ME ; CHEMISTRY & BIODIVERSITY ,2019 ,16 ,-.
Plants of the Amaryllidaceae family are well-known (not only) for their ornamental value but also for the alkaloids that they produce. In this report, the first phytochemical study of Clinanthus genus was carried out. The chemical composition of alkaloid fractions from Clinanthus microstephium was analyzed by GC/MS and NMR. Seven known compounds belonging to three structural types of Amaryllidaceae alkaloids were identified. An epimeric mixture of a haemanthamine-type compound (6-hydroxymaritidine) was tested as an inhibitor against acetyl- and butyrylcholinesterase enzymes (AChE and BChE, respectively), two enzymes relevant in the treatment of Alzheimer's disease, with good results. Structure-activity relationships through molecular docking studies with this alkaloid and other structurally related compounds were discussed.
Llaver, M ;Wuilloud, RG ; MICROCHEMICAL JOURNAL ,2019 ,146 ,763 -770 .
A highly sensitive and selective method based on dispersive micro-solid phase extraction (D-mu-SPE) technique was developed for the determination of inorganic Se species. A very simple and fast preconcentration procedure involving the use of pure nanosilica for the extraction of Se(IV) complexed with ammonium pyrrolidine dithiocarbamate (APDC) was applied. Elution of the retained Se(IV) species from nanosilica was achieved with ethyl acetate followed by electrothermal atomic absorption spectrometry determination. For speciation analysis, Se(VI) was selectively quantified based on the difference between the concentrations of total inorganic Se and Se (IV) after a pre-reduction step. The interaction between the analyte and the extractant was characterized by FT-IR and an adsorption isotherm study. A 90% extraction efficiency was achieved after optimization of all factors concerning the extraction and elution steps, such as pH, ionic strength and type of chelating agent. Optimized conditions included pH = 2.0, 4.9 mu mol L-1 APDC and the use of 1 mg nanosilica as adsorbent. A limit of detection of 1.4 ng L-1, a relative standard deviation of 4.8% and a 90-fold enhancement factor were obtained with 10 mL of sample. The developed method was finally applied to water samples from different origins and compositions, including rain, tap, underground, and sea.
Armendariz, AL ;Talano, MA ; Nicotra, MFO ; Escudero, L ; Breser, ML ; Porporatto, C ; Agostini, E ; PLANT PHYSIOLOGY AND BIOCHEMISTRY ,2019 ,138 ,26 -35 .
Inoculation practice with plant growth-promoting bacteria (PGPB) has been proposed as a good biotechnological tool to enhance plant performance and alleviate heavy metal/metalloid stress. Soybean is often cultivated in soil with high arsenic (As) content or irrigated with As-contaminated groundwater, which causes deleterious effects on its growth and yield, even when it was inoculated with rhizobium. Thus, the effect of double inoculation with known PGPB strains, Bradyrhizobiwn japonicum E109 and Azospirillwn brasilense Az39 was evaluated in plants grown in pots under controlled conditions and treated with As. First, the viability of these co-cultivated bacteria was assayed using a flow cytometry analysis using SYTO9 and propidium iodide (PI) dyes. This was performed in vitro to evaluate the bacterial population dynamic under 25 mu M AsV and AsIII treatment. A synergistic effect was observed when bacteria were co-cultured, since mortality diminished, compared to each growing alone. Indole acetic acid (IAA) produced by A. brasilense Az39 would be one of the main components involved in B. japonicum E109 mortality reduction, mainly under MITI treatment. Regarding in vivo assays, under As stress, plant growth improvement, nodule number and N content increase were observed in double inoculated plants. Furthermore, double inoculation strategy reduced As translocation to aerial parts thus improving As phytostabilization potential of soybean plants. These results suggest that double inoculation with B. japonicum E109 and A. brasilense Az39 could be a safe and advantageous practice to improve growth and yield of soybean exposed to As, accompanied by an important metalloid phytostabilization.
Zodrow, EL ;D'Angelo, JA ; INTERNATIONAL JOURNAL OF COAL GEOLOGY ,2019 ,207 ,12 -25 .
The largest known (365 mm-long) specimen of Odontopteris cantabrica Wagner from the Late Pennsylvanian Sydney Coalfield in Canada was re-examined as part of the on-going research project "Chemistry and Architecture of Carboniferous Seed Ferns" to refine the 3D plant-reconstruction concept further in the framework of natural classification. The micromorphology and functional-group content and distribution of O. cantabrica are investigated by methods of Fourier transform infrared spectroscopy. Results demonstrate that the specimen is naturally macerated, showing little or no cellular features. Two types of stomatal structures occurred, however: anomocytic on abaxial pinnule surfaces, and cyclocytic amphistomatically on the rachises. Hence, the frond was entirely photosynthetic. Chemometric analysis of the infrared data resulted not only in a 3D chemical model, but also confirmed the hypothesis of the chemical-architectural relationship in extinct medullosalean fronds. Further demonstrated is the predictive power of chemometrics for reconstruction, hence frond interpretation, in the absence of certain frond parts. Inferred from the collective data is a basally bifurcate and larger frond, of larger size than previously believed, which could indicate a self-supporting (arborescent) or semi self-supporting habit for the O. cantabrica plant. The concept of natural classification for plant fossils, underpinned by a holistic data approach, is proposed based on data from Neuropteris ovata var. simonii, Alethopteris ambigua, and O. cantabrica.
Campoy, EM ;Branham, MT ; Mayorga, LS ; Roque, M ; BMC CANCER ,2019 ,19 ,-.
Background: Cancer cells evolve and constitute heterogeneous populations that fluctuate in space and time and are subjected to selection generating intratumor heterogeneity. This phenomenon is determined by the acquisition of genetic/epigenetic alterations and their selection over time which has clinical implications on drug resistance.
Quero, G ;Bonnecarrere, V ; Fernandez, S ; Silva, P ; Simondi, S ; Borsani, O ; PHOTOSYNTHESIS RESEARCH ,2019 ,140 ,51 -63 .
One of the main limitations of rice yield in regions of high productive performance is the light-use efficiency (LUE). LUE can be determined at the whole-plant level or at the photosynthetic apparatus level (quantum yield). Both vary according to the intensity and spectral quality of light. The aim of this study was to analyze the cultivar dependence regarding LUE at the plant level and quantum yield using four rice cultivars and four light environments. To achieve this, two in-house Light Systems were developed: Light System I which generates white light environments (spectral quality of 400-700nm band) and Light System II which generates a blue-red light environment (spectral quality of 400-500nm and 600-700nm bands). Light environment conditioned the LUE and quantum yield in PSII of all evaluated cultivars. In white environments, LUE decreased when light intensity duplicated, while in blue-red environments no differences on LUE were observed. Energy partition in PSII was determined by the quantum yield of three de-excitation processes using chlorophyll fluorescence parameters. For this purpose, a quenching analysis followed by a relaxation analysis was performed. The damage of PSII was only increased by low levels of energy in white environments, leading to a decrease in photochemical processes due to the closure of the reaction centers. In conclusion, all rice cultivars evaluated in this study were sensible to low levels of radiation, but the response was cultivar dependent. There was not a clear genotypic relation between LUE and quantum yield.
Cianci, N ;Ottina, M ; TOPOLOGY AND ITS APPLICATIONS ,2019 ,256 ,235 -247 .
We characterize the Hurewicz cofibrations between finite topological spaces, that is, the continuous functions between finite topological spaces that have the homotopy extension property with respect to all topological spaces. In particular, we show that cofibrations between connected non-empty finite topological spaces are homotopy equivalences.
Mayorga, L ;Salassa, BN ; Marzese, DM ; Loos, MA ; Eiroa, HD ; Lubieniecki, F ; Samartino, CG ; Romano, PS ; Roque, M ; CELLULAR AND MOLECULAR LIFE SCIENCES ,2019 ,76 ,1397 -1417 .
Mitochondrial dysfunction represents an important cellular stressor and when intense and persistent cells must unleash an adaptive response to prevent their extinction. Furthermore, mitochondria can induce nuclear transcriptional changes and DNA methylation can modulate cellular responses to stress. We hypothesized that mitochondrial dysfunction could trigger an epigenetically mediated adaptive response through a distinct DNA methylation patterning. We studied cellular stress responses (i.e., apoptosis and autophagy) in mitochondrial dysfunction models. In addition, we explored nuclear DNA methylation in response to this stressor and its relevance in cell survival. Experiments in cultured human myoblasts revealed that intense mitochondrial dysfunction triggered a methylation-dependent pro-survival response. Assays done on mitochondrial disease patient tissues showed increased autophagy and enhanced DNA methylation of tumor suppressor genes and pathways involved in cell survival regulation. In conclusion, mitochondrial dysfunction leads to a pro-survival adaptive state that seems to be triggered by the differential methylation of nuclear genes.
Quevedo, MF ;Bustos, MA ; Masone, D ; Roggero, CM ; Bustos, DM ; Tomes, CN ; BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH ,2019 ,1866 ,612 -622 .
Sperm must undergo the regulated exocytosis of its dense core granule (the acrosome reaction, AR) to fertilize the egg. We have previously described that Rabs3 and 27 are organized in a RabGEF cascade within the signaling pathway elicited by exocytosis stimuli in human sperm. Here, we report the identity and the role of two molecules that link these secretory Rabs in the RabGEF cascade: Rabphilin3a and GRAB. Like Rab3 and Rab27, GRAB and Rabphilin3a are present, localize to the acrosomal region and are required for calcium-triggered exocytosis in human sperm. Sequestration of either protein with specific antibodies introduced into streptolysin O-permeabilized sperm impairs the activation of Rab3 in the acrosomal region elicited by calcium, but not that of Rab27. Biochemical and functional assays indicate that Rabphilin3a behaves as a Rab27 effector during the AR and that GRAB exhibits GEF activity toward Rab3A. Recombinant, active Rab27A pulls down Rabphilin3a and GRAB from human sperm extracts. Conversely, immobilized Rabphilin3a recruits Rab27 and GRAB; the latter promotes Rab3A activation. The enzymatic activity of GRAB toward Rab3A was also suggested by in silico and in vitro assays with purified proteins. In summary, we describe here a signaling module where Rab27A-GTP interacts with Rabphilin3a, which in turn recruits a guanine nucleotide-exchange activity toward Rab3A. This is the first description of the interaction of Rabphilin3a with a GEF. Because the machinery that drives exocytosis is highly conserved, it is tempting to hypothesize that the RabGEF cascade unveiled here might be part of the molecular mechanisms that drive exocytosis in other secretory systems.
Nietiadi, ML ;Millan, EN ; Bringa, EM ; Urbassek, HM ; PHYSICAL REVIEW E ,2019 ,99 ,-.
Available macroscopic theories-such as the Johnson-Kendall-Roberts (JKR) model-predict spherical particles to stick to each other at small collision velocities v; above the bouncing velocity, v(b), they bounce. We study the details of the bouncing threshold using molecular dynamics simulation for crystalline nanoparticles where atoms interact via the Lennard-Jones potential. We show that the bouncing velocity strongly depends on the nanoparticle orientation during collision; for some orientations, nanoparticles stick at all velocities. The dependence of bouncing on orientation is caused by energy dissipation during dislocation activity. The bouncing velocity decreases with increasing nanoparticle radius in reasonable agreement with JKR theory. For orientations for which bouncing exists, nanoparticles stick again at a higher velocity, the fusion velocity, v(f), such that bouncing only occurs in a finite range of velocities-the bouncing window. The fusion velocity is rather independent of the nanoparticle radius.
Scotti, A ;Silvani, VA ; Cerioni, J ; Visciglia, M ; Benavidez, M ; Godeas, A ; INTERNATIONAL JOURNAL OF PHYTOREMEDIATION ,2019 ,21 ,899 -907 .
We present a novel constructed wetland called a vegetable depuration module (VDM) as a pilot test of a bioremediation system (BS) for decontaminating water and soil polluted with heavy metals. The VDM consisted of a pool filled with stones of different granulometry and a substrate top layer composed of a mixture of soil and volcanic ash (50:50, v/v) supplemented with 350 ppm Zn. The BS of sunflower plants colonized by the arbuscular mycorrhizal fungus Rhizophagus intraradices was planted in the VDM. Initially, the substrate registered high concentrations of Zn, Cr, Mn, Cu, and Sr, and had Eh > +500 mV and pH 8.4. Irrigation with a Cu solution by vertical flow was carried out. After 3 months, bioaccumulation factors ranged from 1.00 to 8.90, and translocation rates were >1 for Sr and Cu. Total metals extracted by the BS and percolation were 31%, 34%, 50%, 45%, and 57% for Zn, Cu, Mn, Cr, and Sr, respectively. Only the BS was capable of extracting 94% of Cu and 38% of Zn. VDM allowed us to calibrate the extractive performance of the studied elements in BS. This biotechnological development holds great potential for phytoremediation of polluted areas.
Ferguson, M ;Moyano, MS ; Tribello, GA ; Crawford, DE ; Bringa, EM ; James, SL ; Kohanoff, J ; Del Popolo, MG ; CHEMICAL SCIENCE ,2019 ,10 ,2924 -2929 .
Although solvent-free mechanochemical synthesis continues to gain ever greater importance, the molecular scale processes that occur during such reactions remain largely uncharacterised. Here, we apply computational modelling to indentations between particles of crystals of aspirin and meloxicam under a variety of conditions to mimic the early stages of their mechanochemical cocrystallisation reaction. The study also extends to the effects of the presence of small amounts of solvent. It is found that, despite the solid crystalline nature of the reactants and the presence of little or no solvent, mixing occurs readily at the molecular level even during relatively low-energy collisions. When indented crystals are subsequently drawn apart, a connective neck formed by a mixture of the reactant molecules is observed, suggesting plastic-like behaviour of the reacting materials. Overall the work reveals some striking new insights including (i) relatively facile mixing of crystals under solvent-free conditions, (ii) no appreciable local temperature increases, (iii) localised amorphisation at the contact region and neck of the reacting crystals, and (iv) small amounts of solvent have relatively little effect during this early stage of the reaction, suggesting that their accelerating effect on the reaction may be exerted at later stages.
Quintas, PY ;Alvarez, MB ; Arias, AH ; Garrido, M ; Marcovecchio, JE ; ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH ,2019 ,26 ,7601 -7613 .
Several areas within the Bahia Blanca estuary (BBE), with different maritime traffic intensity, were studied in order to confirm the presence and assess the distribution of tributyltin (TBT), dibutyltin (DBT), and monobutyltin (MBT) in the water column. The organotin compounds (OTCs) were determined in the water samplestaken in summer, autumn, winter, and spring of 2014by gas chromatography coupled to mass spectrometry after liquid-liquid extraction with hexane. The incidence of TBT throughout the whole sampling period indicated a continuous presence of this compound to the study area. However, in accordance with the butyltin degradation index (BDI), TBT was not recently introduced in the BBE. Furthermore, the average TBT levels exceeded the international guideline established by the Oslo-Paris commission (0.62 ng Sn L-1). As a result, certain biological effects could be expected to occur in sensitive species such as mussels. While DBT were below the detection limit in the 75% of the samples analyzed, MBT was detected in all the samples and no significant differences were found among the concentrations measured in the different seasons (Kruskal-Wallis test, p > 0.05). In addition, no correlations were found among the OTCs levels and the evaluated physiochemical parameters (Spearman coefficient, p > 0.05).
Escudero, LB ;Quintas, PY ; Wuilloud, RG ; Dotto, GL ; ENVIRONMENTAL CHEMISTRY LETTERS ,2019 ,17 ,409 -427 .
Industrial activities play a relevant role in environmental pollution since their wastes contain high concentrations of toxic elements that can add significant contamination to natural water and other water sources if no decontamination is previously applied. As toxic metals and metalloids are not biodegradable and tend to accumulate in living organisms, it is necessary to treat the contaminated industrial wastewaters prior to their discharge into the water bodies. There are different remediation techniques that have been developed to solve elemental pollution, but biosorption has arisen as a promising cleanup and low-cost biotechnology. Biosorption is governed by a variety of mechanisms including chemical binding, ion exchange, physisorption, precipitation, and oxide reduction. This review presents applications of biosorbents for metals and metalloids removal. Biomaterials including bacteria, fungi, algae, plant derivatives, agricultural wastes, and chitin-chitosan-based materials are considered. Also, bio-nano-hybrid materials, which have superlative sorption properties due to their high surface area coming from the nanomaterials structures and multifunctional capacity incorporated from the several types of chemical groups of biomaterials, are discussed. High metal removal percentages as high as 70-100% can be found in most works reported in the literature, which demonstrates the excellent performance obtained with biosorbents. These, as well as other important aspects linked to biosorption, are fully covered in the present review.
Vaidheeswaran, A ;Clausse, A ; Fullmer, WD ; Marino, P ; de Bertodano, ML ; CHAOS ,2019 ,29 ,-.
We perform a nonlinear analysis of a fluid-fluid wavy-stratified flow using a simplified two-fluid model (TFM), i.e., the fixed-flux model (FFM), which is an adaptation of the shallow water theory for the two-layer problem. Linear analysis using the perturbation method illustrates the short-wave physics leading to the Kelvin-Helmholtz instability (KHI). The interface dynamics are chaotic, and analysis beyond the onset of instability is required to understand the nonlinear evolution of waves. The two-equation FFM solver based on a higher-order spatiotemporal finite difference scheme is used in the current simulations. The solution methodology is verified, and the results are compared with the measurements from a laboratory-scale experiment. The finite-time Lyapunov exponent (FTLE) based on simulations is comparable and slightly higher than the autocorrelation function decay rate, consistent with previous findings. Furthermore, the FTLE is observed to be a strong function of the angle of inclination, while the root mean square of the interface height exhibits a square-root dependence. It is demonstrated that this simple 1-D FFM captures the essential chaotic features of the interface dynamics. This study also adds to a growing body of work indicating that a TFM with appropriate short wavelength physics is well-behaved and chaotic beyond the KHI. Published under license by AIP Publishing.
Byrne, A ;Bringa, EM ; Del Popolo, MG ; Kohanoff, JJ ; Galassi, V ; English, NJ ; INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES ,2019 ,20 ,-.
Efficient charge transport has been observed in iodine-doped, iodide-based room-temperature ionic liquids, yielding high ionic conductivity. To elucidate preferred mechanistic pathways for the iodide exchange reactions, we have performed 10 ns reactive molecular-dynamics calculations in the liquid state for 1-butyl-3-methylimidazolium iodide ([BMIM][I]) at 450 to 750 K. Energy-barrier distributions for the iodine-swapping process were determined as a function of temperature, employing a charge-reassignment scheme drawn in part from electronic-structure calculations. Bond-exchange events were observed with rate-determining energy barriers ranging from similar to 0.19 to 0.23 +/- 0.06 eV at 750 and 450 K, respectively, with an approximately Arrhenius temperature dependence for iodine self-diffusivity and reaction kinetics, although diffusion dominates/limits the bond-exchange events. This charge transfer is not dissimilar in energetics to those in solid-state superionic conductors.
Ayala, C ;Pennacchio, GE ; Soaje, M ; Bittencourt, JC ; Celis, ME ; Jahn, GA ; Valdez, SR ; Seltzer, AM ; PEPTIDES ,2019 ,113 ,1 -10 .
The Neuropeptide EI (NEI, glutamic acid- isoleucine amide) participates in neuroendocrine function. Previously we demonstrated that NEI concentration is regulated by thyroid hormones in discrete hypothalamic areas in rats. We observed that the thyroid status affects the dopaminergic regulation of the pituitary hormones. In this study we explored possible interactions between NEI and tyrosine hydroxylase (TH) containing elements in selected hypothalamic areas of male rats. Neuronal somas, terminals and boutons were assessed by confocal microscopy, in hypo- and hyperthyroid animals. We observed a remodeling of the contacts between the TH and NEI immunoreactive elements in the incerto-hypothalamic area (IHy, also known as rostromedial zona incerta) according to thyroid function. However, in the dorsolateral zone of the peduncular part of the lateral hypothalamus (DL-PLH) the thyroid hormones affect the dendritic trees of the neurons without perturbing the overall NEI/TH contacts. Also, we demonstrated that TRH Receptor 1 (TRH-R1) is colocalized in NEI immunoreactive neurons in the peduncular part of the lateral hypothalamus (PLH) and NEI precursor mRNA expression increased by hypothyroidism indicating that NEI neurons are responsive to the feedback mechanisms of the Hypothalamic Pituitary-Thyroid Axis (HPT). In conclusion, the hypothyroid status seems to increase the interactions between the NEI neurons and the dopaminergic pathways while hyperthyroidism either decreases or displays no effects. Altogether these observations support the participation of the IHy and PLH NEI as a modulating component of the HPT suggesting that altered neuroendocrine, behavioral and cognitive dysfunctions induced by dysthyroidism could be in part mediated by NEI.
Quintas, PY ;Fernandez, EM ; Spetter, CV ; Arias, AH ; Garrido, M ; Marcovecchio, JE ; ENVIRONMENTAL MONITORING AND ASSESSMENT ,2019 ,191 ,-.
This work provides a preliminary study of the destination, mobility, and availability of tributyltin (TBT), dibutyltin (DBT), and monobutyltin (MBT) in contaminated sediments and water column within Puerto Rosales Port, located in the middle zone of the Bahia Blanca Estuary (Argentina). Therefore, this study presents the first comprehensive results of the role of several physicochemical parameters (temperature, pH, Eh, salinity, turbidity, organic matter, chlorophyll, and macronutrients) in behavior of organotin compounds (OTCs) in a marine-coastal ecosystem. The samples were collected seasonally in May, August, and November during 2014. Levels of OTCs were determined in sediments and water column samples by means of gas chromatography-mass spectrometry analysis. Degradation index analyses suggested not recent inputs of TBT at the area of study. However, results submitted a continuous input of TBT into the column water; further, its distribution and degradation pattern were shown to be influenced by salinity, turbidity, particulate organic matter, chlorophyll, and nitrates. These last two parameters, chlorophyll and nitrates, also were very important for sediment samples. Chlorophyll together with high temperatures recorded in the surface sediments triggers biodegradation process of TBT and DBT resulting in high MBT levels while nitrates seemed to promote debutylation process. Furthermore, pH appeared to influence drastically the adsorption/desorption activity of TBT and DBT in sediment. Finally, the Eh obtained suggested a degradation of TBT thanks to the presence of Fe (III) in this compartment. In addition, in fact, the results outlined a possible MBT additional input that contributes to the pollution observed in the study area.
Sanchez-Puerta, MV ;Edera, A ; Gandini, CL ; Williams, AV ; Howell, KA ; Nevill, PG ; Small, I ; MOLECULAR PHYLOGENETICS AND EVOLUTION ,2019 ,132 ,243 -250 .
Angiosperm mitochondrial horizontal gene transfer (HGT) has been widely reported during the past decades. With a few exceptions, foreign sequences are mitochondrial genes or intronic regions from other plants, indicating that HGT has played a major role in shaping mitochondrial genome evolution. Host-parasite relationships are a valuable system to study this phenomenon due to the high frequency of HGT. In particular, the interaction between mimosoid legumes and holoparasites of the genus Lophophytum represents an outstanding opportunity to discern HGT events. The mitochondrial genome of the holoparasite L. mirabile has remarkable properties, the most extraordinary of which is the presence of 34 out of 43 mitochondrial protein genes acquired from its legume host, with the stunning replacement of up to 26 native homologs. However, the origin of the intergenic sequences that represent the majority (> 90%) of the L. mirabile mtDNA remains largely unknown. The lack of mitochondrial sequences available from the donor angiosperm lineage (mimosoid legumes) precluded a large-scale evolutionary study. We sequenced and assembled the mitochondrial genome of the mimosoid Acacia ligulata and performed genome wide comparisons with L. mirabile. The A. ligulata mitochondrial genome is almost 700 kb in size, encoding 60 genes. About 60% of the L. mirabile mtDNA had greatest affinity to members of the family Fabaceae (similar to 49% to mimosoids in particular) with an average sequence identity of similar to 96%, including genes but mostly intergenic regions. These findings strengthen the mitochondrial fusion compatibility model for angiosperm mitochondrion-to-mitochondrion HGT.
Giraud-Billoud, M ;Castro-Vazquez, A ; ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY ,2019 ,169 ,573 -582 .
Ampullariidae are unique among gastropods in that females normally show a primordium of the copulatory apparatus (CApp). The aims of this study were (a) to quantitatively evaluate the development and growth of the female CApp with age; (b) to compare the effects of RXR and PPARy agonists in adult females of known age and (c) to explore the effect of masculinizing RXR agonists on the expression of RXR in the CApp. It was found that the CApp grows and develops with age. A significant increase in penile sheath length (PsL) and also in a developmental index (DI) was observed in 7-8 months old females, as compared with 4-5 months old ones. A reported endogenous agonist of RXR, 9-cis retinoic acid (9cis-RA), as well as two organotin compounds, tributyltin (TBT) and triphenyltin (TPT) which have been also reported to bind to RXR, were injected and its masculinizing effects were measured. Also, the effect of a PPARy agonist, rosiglitazone, was studied. All studied RXR agonists, but not the PPAR gamma agonist, were effective in increasing PsL, penile length (PL) and DI. Finally, the expression of the RXR in the CApp was studied (Western blot) in control, TBT, TPT, and 9cis-RA treated females. A significantly increased expression of RXR was only observed after 9cis-RA treatment. It is concluded that (a) development and growth of the CApp is significantly affected by female age; (b) reported RXR agonists, but not a PPARy agonist, cause female masculinization of young females. An appraisal of previous studies of female masculinization in the Ampullariidae has also been made and it is emphasized that the masculinizing effect of aging should be considered, particularly when interpreting field data.
Grassi, P ;Reis, C ; Drumm, FC ; Georgin, J ; Tonato, D ; Escudero, LB ; Kuhn, R ; Jahn, SL ; Dotto, GL ; WATER SCIENCE AND TECHNOLOGY ,2019 ,79 ,709 -717 .
An inactive biomass of a new fungus recently discovered, Diaporthe schini, was evaluated for the biosorption of crystal violet (CV) in simulated textile effluents. The characterization assays were performed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and N-2 adsorption/desorption isotherms. The influences of pH and biosorbent dosage on the biosorption capacity were evaluated. Kinetics, equilibrium and thermodynamic studies were also carried out. Characterization techniques showed an amorphous biosorbent, with a rough surface containing irregular particles and surface area of 6.5 m(2) g(-1). The most adequate values of pH and biosorbent dosage were 7.5 and 0.4 g L-1, respectively. The Elovich kinetic model and the Sips equilibrium model were suitable to fit the experimental data. The biosorption capacity increased with temperature, reaching a maximum biosorption capacity of 642.3 mg g(-1 )at 328 K. The biosorption was a spontaneous and endothermic process. Diaporthe schini inactive biomass was an interesting biosorbent to treat colored effluents, presenting efficiency of 87% in the decolorization of a simulated dye house effluent.
Bulgariu, L ;Escudero, LB ; Bello, OS ; Iqbal, M ; Nisar, J ; Adegoke, KA ; Alakhras, F ; Kornaros, M ; Anastopoulos, I ; JOURNAL OF MOLECULAR LIQUIDS ,2019 ,276 ,728 -747 .
The presence of organic dyes in the aquatic environment is a serious global problem because of the serious negative consequences on the quality of ecosystems. Among various physico-chemical methods, the adsorption could be considered a promising alternative for removing dyes from aqueous media, due to its efficiency, high selectivity, low cost, ease of operation, simplicity, and availability in a wide range of experimental conditions. However, all these advantages are closely related to the nature of adsorbent material used in the adsorption processes of dyes. The adsorbent materials available in large quantities requiring a simple preparation will enhance the benefits of the adsorption processes, in agreement with the concepts of green chemistry. This review is focused on the use of leaf-based materials, in raw or modified forms, as adsorbents for the removal of dyes from aqueous effluents, with applications in the wastewater treatment. This review addresses characterization of leaf-based adsorbents, possible utilization of leaf-based adsorbents (raw and activated forms) for dye removal and possible applications in pilot and full scale systems. Also, thermodynamics, equilibrium and kinetic parameters of dye adsorption on leaf-based adsorbents are discussed. The practical utility of leaf-based adsorbents for dye removal, and their possible uses in the treatment of industrial wastewater are copiously highlighted. (C) 2018 Elsevier B.V. All rights reserved.
Andrade, JA ;Lobos, AM ; PHYSICAL REVIEW B ,2019 ,99 ,-.
We theoretically consider a quantum magnetic impurity coupled to a superconductor and obtain the local density of states at the position of the impurity taking into account the effect of spin fluctuations and single-ion magnetic anisotropy. We particularly focus on the spectrum of subgap Yu-Shiba-Rusinov (YSR or Shiba) states induced by a quantum impurity with easy- or hard-axis uniaxial anisotropy. Although this is a relevant experimental situation in, e.g., magnetic adatoms on the surface of clean metals, it is customary that theoretical descriptions assume a classical-spin approximation which is not able to account for single-ion anisotropy and other quantum effects. Here, quantum fluctuations of the spin are taken into account in the equations of motion of the electronic Green's function in the weak-coupling limit and considerably modify the energy of the Shiba states compared to the classical-spin approximation. Our results point towards the importance of incorporating quantum fluctuations and anisotropy effects for the correct interpretation of scanning tunneling microscopy (STM) experiments.
Manzur, MJ ;Aguilera, MO ; Kotler, ML ; Beron, W ; Ciuffo, GM ; JOURNAL OF CELLULAR BIOCHEMISTRY ,2019 ,120 ,1835 -1849 .
Apoptosis plays an important role in cellular processes such as development, differentiation, and homeostasis. Although the participation of angiotensin II (Ang II) AT(2) receptors (AT R-2) in cellular apoptosis is well accepted, the signaling pathway involved in this process is not well established. We evaluated the participation of signaling proteins focal adhesion kinase (FAK), RhoA, and p38 mitogen-activated protein kinase (p38MAPK) in apoptosis induced by Ang II via AT R-2 overexpressed in HeLa cells. Following a short stimulation time (120 to 240minutes) with Ang II, HeLa-AT (2) cells showed nuclear condensation, stress fibers disassembly and membrane blebbing.FAK, classically involved in cytoskeleton reorganization, has been postulated as an early marker of cellular apoptosis. Thus, we evaluated FAK cleavage, detected at early stimulation times (15 to 30minutes). Apoptosis was confirmed by increased caspase-3 cleavage and enzymatic activity of caspase-3/7. Participation of RhoA was evaluated. HeLa-AT (2) cells overexpressing RhoA wild-type (WT) or their mutants, RhoA V14 (constitutively active form) or RhoA N19 (dominant-negative form) were used to explore RhoA participation. HeLa-AT (2) cells expressing the constitutively active variant RhoA V14 showed enhanced apoptotic features at earlier times as compared with cells expressing the WT variant. RhoA N19 expression prevented nuclear condensation/caspase activation. Inhibition of p38MAPK caused an increase in nuclear condensation and caspase-3/7 activation, suggesting a protective role of p38MAPK. Our results clearly demonstrated that stimulation of AT R-2 induce apoptosis with participation of FAK and RhoA while p38MAPK seems to play a prosurvival role.
Fusari, CM ;Ramirez, DA ; Camargo, AB ; ANALYTICAL METHODS ,2019 ,11 ,309 -316 .
Miniaturized extraction techniques are one of the most significant advances in analytical chemistry today. Nowadays there is a growing tendency among food researchers to develop simpler and robust methodologies that allow the determination of multiple analytes in different samples. Based on this concept, the aim of this work was to develop an optimized and validated methodology for the determination of four isothiocyanates (ITCs) and one indole: allyl ITC, erucin, sulforaphane, phenyl ITC and indole-3-carbinol present in Brassicaceae vegetables. Experimental design and multivariate analysis were the statistical tools used during the process. The dispersive liquid-liquid microextraction (DLLME) technique developed in this work was successfully applied to the analysis of nine Brassicaceae species.
Masone, D ;Bustos, DM ; PHYSICAL CHEMISTRY CHEMICAL PHYSICS ,2019 ,21 ,268 -274 .
Are the dimerization of transmembrane (TM) domains and the reorganization of the lipid bilayer two independent events? Does one event induce or interfere with the other? In this work, we have performed well-tempered metadynamics simulations to calculate the free energy cost to bend a model ternary lipid bilayer in the presence of a TM peptide in its dimer form. We have compared this result with the free energy cost needed to bend a bilayer-only system. Additionally, we have calculated the free energy cost to form a model TM peptide dimer quantitatively describing how lipids reorganize themselves in response to the increase of the membrane curvature and to the lipid-peptide interactions. Our results indicate that the formation of the peptide dimer inside the bilayer increases the cost of the membrane bending due to the spontaneous clustering of cholesterol molecules.
Dewar, G ;Marsh, EJ ; JOURNAL OF ISLAND & COASTAL ARCHAEOLOGY ,2019 ,14 ,17 -45 .
This paper evaluates chronological trends in the presence and absence of domestic animal bone (sheep, goat, and cattle) and pottery in Namaqualand, the proposed gateway to the rest of South Africa for early herders or hunter-gatherers with sheep and ceramics. We update date calibrations with local Delta R corrections and mixtures of recent calibration curves and include five previously unpublished dates. We use histograms of calibrated medians, sorted in 100-year bins, to assess sustained regional patterns with dates associated with domestic animal bone and pottery (n = 73). While too small to be useful as a population proxy, the current set of dates does reveal three pulses of occupation separated by two clear gaps, which we evaluate with a Bayesian model of three sequential phases. The model's boundaries are used as estimates of the dates of Early (AD 80-210), Middle (AD 490-790), and Late (AD 1180-1690) occupational phases separated by two substantial lapses of 280 and 380 years, respectively. The alternating phases of presence and absence are suggestively correlated with climate shifts, leading to a discussion of the idea that effective moisture was a crucial factor in choosing whether to occupy Namaqualand. The set of archaeological dates has greater temporal and spatial resolution than many regional climate data, so we suggest that these trends may more accurately reflect the variable conditions specific to Namaqualand, at least until they are refined by future climate research.
Mundo, IA ;Rovida-Kojima, EA ; Aschero, V ; BOSQUE ,2019 ,40 ,217 -226 .
Despite the extensive literature on model fitting to estimate volume in different tree species and regions of Argentina, the references related to volume equations for Populus spp. in irrigated plantations in the Province of Mendoza arc scarce. This information is essential for silvicultural management. The objectives of this study were: 1) to calculate and compare the artificial form factors for Populus x canadensis 'Conti 12' and 'Guardi' clones growing in irrigated plantations in Uco Valley, Mendoza, 2) to fit and compare different equations of stem volume with bark for these two clones and 3) to evaluate the possibility of using a single function to estimate this parameter in both clones. Seven models previously used on Populus in Argentina were fitted to estimate the total stem volume per tree. The form factors for 'Conti 12' and 'Guardi' were different between them (0.44 and 0.38, respectively). For both, 'Conti 12' and 'Guardi', the adjustment of the seven models allowed estimating the total stem volume with bark with a very high and similar degree of precision, although in both situations two models (Schumacher-Hall and a variant of the standard function with constant form factor) highlighted over the rest. The statistics of self-validation, homoscedasticity and parsimony criteria allow favoring the decision for the Schumacher-Hall model adjusted individually for each clone and not as a general expression.
Riga, BJG ;Lamanna, MC ; Otero, A ; David, LDO ; Kellner, AWA ; Ibiricu, LM ; ANAIS DA ACADEMIA BRASILEIRA DE CIENCIAS ,2019 ,91 ,-.
In the last two decades, the number of phylogenetically informative anatomical characters recognized in the appendicular skeleton of titanosaurian sauropod dinosaurs has increased dramatically with the discovery of new and comparatively complete specimens. Here we provide an overview of the appendicular skeletal morphology of South American titanosaurs and discuss its significance for phylogenetic reconstruction. The appendicular skeletal diversity of South American titanosaurs is substantially greater than was initially appreciated. Moreover, some regions of the appendicular skeleton, such as the pes, exhibit remarkable variability in form. Multiple synapomorphies of Titanosauria and the less inclusive clades Lithostrotia and Saltasauridae consist of characters of the girdles and limbs. Although the phylogenetic definitions of titanosaurian clades such as Saltasaurinae and Lognkosauria are stable, the taxonomic content of these chides has varied in recent analyses depending on the phylogenetic topology recovered. Within Titanosauria, the results of four recent, largely independent analyses support the existence of a derived titanosaurian lineage distinct from the 'Saltasaurinae line,' which is herein termed Colossosauria. At present, this clads is mainly comprised by taxa within Lognkosauria and Rinconsauria, and is useful in discussions of titanosaurian lower-level relationships.
Ubaldini, S ;Guglietta, D ; Trapasso, F ; Carloni, S ; Passeri, D ; Scotti, A ; CHEMISTRY JOURNAL OF MOLDOVA ,2019 ,14 ,32 -46 .
This paper presents an overview of the various innovative methodologies used in the recovery of valuable metals and critical raw materials (CRMs) from secondary sources. Valuable metals are interesting due to their vast industrial applications, high market prices and extensively used precious metal. The sanctuary value attributed to valuable metals such as gold during international political and economical crises and the limited resource of this metal, may explain the recent increasing gold share value. This article provides an overview of past achievements and presents scenario of studies carried out on the use of some promising methods which could serve as an economical means for recovering valuable metals and CRMs. The review also highlights the used varieties of application on large scale in real situations and hopes to provide insights into valorization of spent sources.
Calvo, JO ;Riga, BG ; ANAIS DA ACADEMIA BRASILEIRA DE CIENCIAS ,2019 ,91 ,-.
We describe a dentary of a new titanosaur sauropod, Baalsaurus mansillai, gen. et sp. nov. from the Late Cretaceous of Patagonia, Argentina. The material comes from the Portezuelo Formation, Neuquen Group. Titanosaur sauropods lower jaws are scarce and only nine taxa with dentaries have been described. There are two types of morphology in titanosaur dentaries; "L" shaped or "U" shaped based on the shape, without a phylogenetic issue. In this paper; we recognize a new taxa, Baalsaurus mansillai, represented by an "L" shaped dentary with three apomorphic characters that are not present in other taxa: dentary alveoli with 10 teeth in the anterior ramus, a ventrally and anteriorly inclined symphysis and a wide ventral Meckelian groove surrounded by a thin lamina that forms a keel on the ventral border of the dentary.
Romero, ALN ;Moratta, MAH ; Rodriguez, MR ; Quiroga, LB ; Echegaray, M ; Sanabria, EA ; ECOTOXICOLOGY ,2019 ,28 ,48 -61 .
We evaluated the toxicity of the winery effluent and the efficiency of a symbiotic depuration system by means an experiment with Rhinella arenarum tadpoles. The studied effluent was taken from warehouses during the cleaning season. These effluents subsequently subjected to the purification treatment under evaluation. The effluent samples differentiated into two treatment levels: raw where the effluent was evaluated with field conditions and treated where the effluent was previously filtered with the symbiotic depuration system. The results of the bioassays compared with the physicochemical parameters determined in the effluent samples. The lethal response had a clear-cut correspondence with the effluent quality assessed utilizing physicochemical parameters. In all cases, dilution of the samples resulted in a significant reduction of their toxicity. It concluded that (a) winery effluents could be harmful to tadpoles of R. arenarum, (b) the symbiotic purification system used to treat wine effluents it would produce a significant reduction in the contaminant levels of the effluent. However, this reduction in contaminant levels does not provide sufficient safety for the release of the effluents into the environment.
Hernandez, IG ;Palottini, F ; Macri, I ; Galmarini, CR ; Farina, WM ; JOURNAL OF EXPERIMENTAL BIOLOGY ,2019 ,222 ,-.
The honey bee is the most frequently used species in pollination services for diverse crops. In onion crops (Allium cepa), however, bees avoid visiting certain varieties, being attracted differently to male sterile (MS) and fertile (OP) lines. These differences might be based on the phenolic profiles of the cultivars' nectars. To understand the relationship between nectar composition and pollinator attraction to different onion lines, we tested sensory and cognitive abilities and palatability in honey bees exposed to MS and OP onion nectars and sugar solutions mimicking them. We evaluated the proboscis extension response (PER) after antennal contact (unconditioned response) to MS or OP onion nectars, finding no statistical differences, which indicates similar gustatory perception for the two nectars. We also performed food uptake assays to test palatability of different artificial nectars, considering their flavonoids and potassium content. The presence of potassium decreased the palatability of the artificial nectars. Finally, we evaluated the bees' cognitive abilities when the reward (unconditioned stimulus) offered during conditioning PER assays presents differences in composition. We found that potassium by itself impaired learning; however, such impairment was even higher when naringenin and quercetin were added in the unconditioned stimulus (MS nectar mimic). Interestingly, potassium together with luteolin (OP nectar mimic) improved learning. Our study demonstrates that the differences in the nectars' flavonoid profiles combined with their high potassium content could explain the previously reported differences in attractiveness between onion lines, suggesting an important role of nectar compounds other than sugars for the attractiveness of flowers to pollinators.
Gonzalez, CV ;Jerez, DN ; Jofre, MF ; Guevara, A ; Prieto, J ; Mazza, C ; Williams, LE ; Giordano, CV ; ENVIRONMENTAL AND EXPERIMENTAL BOTANY ,2019 ,157 ,112 -120 .
Grapevine is one of the most important fruit crops worldwide. Vineyard management practices affect light interception and spectral characteristics inside the canopy. Plant photoreceptors drive shade acclimation responses after the perception of light signals such as low photosynthetic active radiation (PAR), low blue light (BL) levels and low red-to-far red ratios (R:FR). Grapevine plants effectively acclimate to shade but are irresponsive to variations in R:FR perceived by phytochromes. To determine if BL attenuation mediate shade acclimation in this species, we manipulated sunlight reaching the plants by filtering. Vitis vinifera cv. Malbec plants were grown under low (LOW PAR) and high (HIGH PAR) neutral light environments, and under high light but attenuating the BL component of the spectrum (-BLUE). We evaluated morphological, biochemical and architectural responses to shade, and modelled light interception (LIE) and absorption (E-a) efficiencies. We found that plants grown under -BLUE mimicked morphological and architectural responses of plants cultivated under LOW PAR. In addition, LIE and E-a were higher in plants grown under -BLUE and LOW PAR than in HIGH PAR. Our findings suggest that morphological and architectural responses to shade are under the control of BL-photo-receptors in grapevine. However, BL attenuation failed to induce the accumulation of photosynthetic pigments in leaves observed under LOW PAR. Unchanged biomass accumulation across light treatments suggests that improved light capture counterbalanced irradiance reduction. These results might help in the design of practices that manipulate irradiance in the field, and that are increasingly being used as environment-friendly management tools to improve crop performance.
Riga, BJG ;Tomaselli, MB ; CRETACEOUS RESEARCH ,2019 ,93 ,49 -59 .
The discovery of new Titanopodus trackways (Loncoche Formation, Argentina) shed light on the locomotion of titanosaur sauropods. Two patterns related with different size of trackmakers are identified based on ichnological and anatomical evidences. AC-1 and AC-4 trackways (pattern 1) are characterized by alternated manus and pes tracks. This is congruent with an asynchronous gait produced by large individuals that walked at 4.7-4.8 km/h. AC-3 trackway (pattern 2) shows some elongated and distorted tracks interpreted as overlapped manus and pes prints. This interpretation is supported by the presence of clear juxtaposed or partially overlapped manus and pes prints in some parts of the trackway. Pattern 2 is preliminary assigned to an amble gait produced by a smaller individual that walked at 3.7 km/h. These two patterns can be analyzed as different gaits in titanosaurs that walked together. (C) 2018 Elsevier Ltd. All rights reserved.
Barberena, R ;Fernandez, MV ; Rughini, AA ; Borrazzo, K ; Garvey, R ; Lucero, G ; Della Negra, C ; Villanueva, GR ; Duran, V ; Cortegoso, V ; Giesso, M ; Klesner, C ; MacDonald, BL ; Glascock, MD ; GEOARCHAEOLOGY-AN INTERNATIONAL JOURNAL ,2019 ,34 ,30 -41 .
Northwestern Patagonia is located in a tectonically active part of the southern Andes (Argentina), which has facilitated the formation of obsidian, including pyroclastic deposits that have been affected by geomorphic processes, resulting in a complex obsidian landscape. To date, the geomorphic relocation of obsidian in the landscape has not been a focus of systematic research, and this hampers our understanding of prehistoric human mobility. We present an updated assessment of the regional availability of different obsidian types based on results from our research program, which combines geoarchaeological survey and geochemical characterization to understand the properties and distribution of obsidian. This robust "source-scape" provides the foundation for reconstructing patterns of lithic provisioning and discard. Our results suggest that interpretations of obsidian availability across the landscape should be more nuanced than is typically acknowledged. Based on our improved "source-scape," we discuss the patterns observed in an archaeological X-ray fluorescence database. When compared with the geoarchaeological reconstruction of obsidian availability, the archaeological record conforms to a distance-decay pattern. Contrary to previous interpretations, we suggest that the distribution of obsidian types is not isomorphic with human home ranges. This geoarchaeological research program provides a basis for integrating the archaeological record of different Andean regions.
Grossi, J ;Shah, SH ; Artacho, E ; Bristowe, PD ; PHYSICAL REVIEW MATERIALS ,2018 ,2 ,-.
The stability of (Cr-x, V1-x)(2)AlC MAX phases, materials of interest for a variety of magnetic as well as high-temperature applications, has been studied using density-functional-theory first-principles calculations. The enthalpy of mixing predicts these alloys to be unstable towards unmixing at 0 K. The calculations also predict, however, that these phases would be thermally stabilized by configurational entropy at temperatures well below the values used for synthesis. The temperature T-s below which they become unstable is found to be quite sensitive to the presence of magnetic moments on Cr ions, as well as to the material's magnetic order, in addition to chemical order and composition. Allowing for magnetism, the value of T-s for (Cr-0.5, V-0.5)(2)AlC with chemically disordered Cr and V atoms is estimated to be between 516 and 645 K depending on the level of theory, while if constrained to spin paired, T-s drops to similar to 142 K. Antiferromagnetic spin arrangements are found to be favored. The combination of antiferromagnetic frustration and configurational disorder should give rise to interesting spin textures at low temperatures.
Cappa, AI ;de Paola, M ; Wetten, P ; De Blas, GA ; Michaut, MA ; BIOLOGY OPEN ,2018 ,7 ,-.
Oocyte in vitro maturation does not entirely support all the nuclear and cytoplasmic changes that occur physiologically, and it is poorly understood whether in vitro maturation affects the competence of cortical granules to secrete their content during cortical reaction. Here, we characterize cortical granule exocytosis (CGE) in live mouse oocytes activated by strontium chloride using the fluorescent lectin FITC-LCA. We compared the kinetic of CGE between ovulated (in vivo matured, IVO) and in vitro matured (IVM) mouse oocytes. Results show that: (1) IVM oocytes have a severely reduced response to strontium chloride; (2) the low response was confirmed by quantification of remnant cortical granules in permeabilized cells and by a novel method to quantify the exudate in non-permeabilized cells; (3) the kinetic of CGE in IVO oocytes was rapid and synchronous; (4) the kinetic of CGE in IVM oocytes was delayed and asynchronous; (5) cortical granules in IVM oocytes show an irregular limit in regards to the cortical granule free domain. We propose the analysis of CGE in live oocytes as a biological test to evaluate the competence of IVM mouse oocytes.
Sales, RG ;Guida-Johnson, B ; REVISTA DE GEOGRAFIA NORTE GRANDE ,2018 ,,109 -124 .
Drylands degradation is a threat to the well-being of the population living in that territory, which also presents imbalances around the historical polarized configuration between irrigated and non-irrigated lands. In this research we applied a qualitative methodology to study the environmental perceptions of small livestock ranching producers living in the non-irrigated area of Mendoza in order to identify problems related to the access and quality of water and the production of food for self-consumption. We highlight the importance of knowing the environmental perception of the local community to define the conflicts and then carry out specific studies that enable the identification of the causes of degradation. Incorporating the social dimension during the design of the measures to be implemented will allow the public policy to readjust its guidelines to improve the obtained results. In addition, it will enrich the generation of management recommendations.
Mayorga, LS ;Cebrian, I ; Verma, M ; Hoops, S ; Bassaganya-Riera, J ; BIOLOGY DIRECT ,2018 ,13 ,-.
BackgroundReproducing cell processes using an in silico system is an essential tool for understanding the underlying mechanisms and emergent properties of this extraordinary complex biological machine. However, computational models are seldom applied in the field of intracellular trafficking. In a cell, numerous molecular interactions occur on the surface or in the interior of membrane-bound compartments that continually change position and undergo dynamic processes of fusion and fission. At present, the available simulation tools are not suitable to develop models that incorporate the dynamic evolution of the cell organelles.ResultsWe developed a modeling platform combining Repast (Agent-Based Modeling, ABM) and COPASI (Differential Equations, ODE) that can be used to reproduce complex networks of molecular interactions. These interactions occur in dynamic cell organelles that change position and composition over the course of time. These two modeling strategies are fundamentally different and comprise of complementary capabilities. The ODEs can easily model the networks of molecular interactions, signaling cascades, and complex metabolic reactions. On the other hand, ABM software is especially suited to simulate the movement, interaction, fusion, and fission of dynamic organelles. We used the combined ABM-ODE platform to simulate the transport of soluble and membrane-associated cargoes that move along an endocytic route composed of early, sorting, recycling and late endosomes. We showed that complex processes that strongly depend on transport can be modeled. As an example, the hydrolysis of a GM2-like glycolipid was programmed by adding a trans-Golgi network compartment, lysosomal enzyme trafficking, endosomal acidification, and cholesterol processing to the simulation model.ConclusionsThe model captures the highly dynamic nature of cell compartments that fuse and divide, creating different conditions for each organelle. We expect that this modeling strategy will be useful to understand the logic underlying the organization and function of the endomembrane system.ReviewersThis article was reviewed by Drs. Rafael Fernandez-Chacon, James Faeder, and Thomas Simmen.
Godoy, PD ;Cayssials, RL ; Garino, CGG ; COMPUTERS & ELECTRICAL ENGINEERING ,2018 ,72 ,846 -858 .
Wireless sensor networks (WSN) may be composed by tens or hundreds of nodes. Nodes measure variables and send their values to a base station through a shared low data rate wireless communication channel. Communication protocols for WSNs have been developed in order to support a large number of nodes. However, if a great deal of data is transmitted through a low speed communication channel, data packet congestion may happen. Congestion may lead to high latencies or data loss. Data congestion could take place in WSNs with a large number of nodes sending data periodically, or in WSNs where the data rate can increase when a specific event is detected. In this paper we analyze the conditions that lead to congestion of the communication channel considering the following nodes configuration parameters: (1) transmission time intervals, (2) data packet generation rate, and (3) transmitter output power level. (C) 2017 Elsevier Ltd. All rights reserved.
Elola, MT ;Ferragut, F ; Mendez-Huergo, SP ; Croci, DO ; Bracalente, C ; Rabinovich, GA ; CELLULAR IMMUNOLOGY ,2018 ,333 ,34 -45 .
Tumor cells corrupt surrounding normal cells instructing them to support proliferative, pro-angiogenic and immunosuppressive networks that favor tumorigenesis and metastasis. This dynamic cross-talk is sustained by a range of intracellular signals and extracellular mediators produced by both tumoral and non-tumoral cells. Galectins-whether secreted or intracellularly expressed- play central roles in the tumorigenic process by delivering regulatory signals that contribute to reprogram fibroblasts, endothelial and immune cell programs. Through glycosylation-dependent or independent mechanisms, these endogenous lectins control a variety of cellular events leading to tumor cell proliferation, survival, migration, inflammation, angiogenesis and immune escape. Here we discuss the role of galectin-driven pathways, particularly those activated in non-tumoral stromal cells, in modulating tumor progression.
Valencia, FJ ;Gonzalez, RI ; Vega, H ; Ruestes, C ; Rogan, J ; Valdivia, JA ; Bringa, EM ; Kiwi, M ; JOURNAL OF PHYSICAL CHEMISTRY C ,2018 ,122 ,25035 -25042 .
Palladium nanoparticles are technologically important for catalysis, hydrogen storage, and many other applications. Here, we investigate the mechanical properties of Pd hollow nanoparticles of different sizes and thicknesses by means of classical molecular dynamics simulations. Hollow nanospheres of sizes ranging from 5 to 40 nm are compressed using planar indenters. Our results suggest that the mechanical response of hollow nanoparticles can be tailored by tuning the external radius (R) and shell thickness (omega). The largest elastic limit for a given thickness is achieved when the aspect ratio A = R/omega is 3 <= A <= 4. This delay of the onset of plastic deformation is due to the fact that, for this geometry, hollow nanoparticles can buckle, avoiding stress concentration in the contact; this in turn favors stress accumulation and dislocation behavior of solid nanoparticles and "bulk" surfaces.
Craine, JM ;Elmore, AJ ; Wang, LX ; Aranibar, J ; Bauters, M ; Boeckx, P ; Crowley, BE ; Dawes, MA ; Delzon, S ; Fajardo, A ; Fang, YT ; Fujiyoshi, L ; Gray, A ; Guerrieri, R ; Gundale, MJ ; Hawke, DJ ; Hietz, P ; Jonard, M ; Kearsley, E ; Kenzo, T ; Makarov, M ; Maranon-Jimenez, S ; McGlynn, TP ; McNeil, BE ; Mosher, SG ; Nelson, DM ; Peri, PL ; Roggy, JC ; Sanders-DeMott, R ; Song, MH ; Szpak, P ; Templer, PH ; Van der Colff, D ; Werner, C ; Xu, XL ; Yang, Y ; Yu, GR ; Zmudczynska-Skarbek, K ; NATURE ECOLOGY & EVOLUTION ,2018 ,2 ,1735 -1744 .
Human societies depend on an Earth system that operates within a constrained range of nutrient availability, yet the recent trajectory of terrestrial nitrogen (N) availability is uncertain. Examining patterns of foliar N concentrations and isotope ratios (delta N-15) from more than 43,000 samples acquired over 37 years, here we show that foliar N concentration declined by 9% and foliar delta N-15 declined by 0.6-1.6 parts per thousand. Examining patterns across different climate spaces, foliar delta N-15 declined across the entire range of mean annual temperature and mean annual precipitation tested. These results suggest declines in N supply relative to plant demand at the global scale. In all, there are now multiple lines of evidence of declining N availability in many unfertilized terrestrial ecosystems, including declines in delta N-15 of tree rings and leaves from herbarium samples over the past 75-150 years. These patterns are consistent with the proposed consequences of elevated atmospheric carbon dioxide and longer growing seasons. These declines will limit future terrestrial carbon uptake and increase nutritional stress for herbivores.
Quero, G ;Gutierrez, L ; Monteverde, E ; Blanco, P ; de Vida, FP ; Rosas, J ; Fernandez, S ; Garaycochea, S ; McCouch, S ; Berberian, N ; Simondi, S ; Bonnecarrere, V ; PLANT GENOME ,2018 ,11 ,-.
Rice (Oryza sativa L.) is one of the most important staple food crops in the world; however, there has recently been a shift in consumer demand for higher grain quality. Therefore, understanding the genetic architecture of grain quality has become a key objective of rice breeding programs. Genome-wide association studies (GWAS) using large diversity panels have successfully identified genomic regions associated with complex traits in diverse crop species. Our main objective was to identify genomic regions associated with grain quality and to identify and characterize favorable haplotypes for selection. We used two locally adapted rice breeding populations and historical phenotypic data for three rice quality traits: yield after milling, percentage of head rice recovery, and percentage of chalky grain. We detected 22 putative quantitative trait loci (QTL) in the same genomic regions as starch synthesis, starch metabolism, and cell wall synthesis-related genes are found. Additionally, we found a genomic region on chromosome 6 in the tropical japonica population that was associated with all quality traits and we identified favorable haplotypes. Furthermore, this region is linked to the OsBEI gene that codes for a starch branching enzyme I, which is implicated in starch granule formation. In tropical japonica, we also found two putative QTL linked to OsBEII, OsDEP1, and OsDEP2. Our study provides an insight into the genetic basis of rice grain chalkiness, yield after milling, and head rice, identifying favorable haplotypes and molecular markers for selection in breeding programs.
Tripp, NG ;Mirasso, AE ; Preidikman, S ; JOURNAL OF INTELLIGENT MATERIAL SYSTEMS AND STRUCTURES ,2018 ,29 ,3533 -3549 .
Larger and more flexible wind turbine blades are currently being manufactured. Those highly flexible blades suffer from loading of aeroelastic nature which increases the fatigue damage. Smart blade concepts are being developed to reduce the aerodynamic loading. The state of the art favors the discrete deformable trailing edge concept. Many authors have reported adequate performance of this type of actuators in reducing the blade vibrations. However, the question of whether the actuator can maintain its authority under strong external loading remains still answered. To solve this question, actuator models that include the loading produced by the blade vibration are required. In this article, a smart morphing trailing edge model is presented that includes the inertial forces produced by the blade dynamics. The model is applied to a commercial actuator and the influence of its parameters is analyzed. Finally, a simple estimation of the inertial loading produced by a 35-m wind turbine blade at the flutter instability condition is analyzed to understand the design requirements of this type of systems.
Santos-Florez, PA ;Ruestes, CJ ; de Koning, M ; JOURNAL OF CHEMICAL PHYSICS ,2018 ,149 ,-.
Using molecular dynamics simulations, we assess the uniaxial deformation response of ice I-h as described by two popular water models, namely, the all-atom TIP4P/Ice potential and the coarse-grained mW model. In particular, we investigate the response to both tensile and compressive uniaxial deformations along the  and [0 (1) over bar 10] crystallographic directions for a series of different temperatures. We classify the respective failure mechanisms and assess their sensitivity to strain rate and cell size. While the TIP4P/Ice model fails by either brittle cleavage under tension at low temperatures or large-scale amorphization/melting, the mW potential behaves in a much more ductile manner, displaying numerous cases in which stress relief involves the nucleation and subsequent activity of lattice dislocations. Indeed, the fact that mW behaves in such a malleable manner even at strain rates that are substantially higher than those applied in typical experiments indicates that the mW description of ice I-h is excessively ductile. One possible contribution to this enhanced malleability is the absence of explicit protons in the mW model, disregarding the fundamental asymmetry of the hydrogen bond that plays an important role in the nucleation and motion of lattice dislocations in ice I-h. Published by AIP Publishing.
Rodriguez, C ;Prieto, GI ; Vega, IA ; Castro-Vazquez, A ; PEERJ ,2018 ,6 ,-.
Knowledge on the immune system of Pomacea canaliculata is becoming increasingly important, because of this gastropod's role as intermediate host and vector of Angiostrongylus cantonensis, the etiologic agent of eosinophilic meningitis in humans and domestic animals. Immune defenses of this gastropod comprise both humoral and cellular components, but they may also involve organs that act as immune barriers to prevent the spread of alien molecules and organisms. Both the kidney and lung are here shown to serve this function, because of (1) their positions in blood circulation, (2) the intricate architecture of their blood spaces, and (3) the proliferative and nodulation reactions of hemocytes to an immune challenge. However, these organs differ in that only the kidney shows permanent hemocyte aggregations. Microcirculation in the kidney was found to flow through an intricate vascular bed containing the permanent aggregations, which occurred either as hemocyte islets anchored by cytoplasmic projections of the renal epithelium or as perivascular accretions. Within 96 h of the injection of yeast cells, hemocyte nodules were formed both in the kidney and lung. Moreover, cell proliferation in renal hemocyte islets was measured by bromodeoxyuridine (BrdU) incorporation. The proportion of BrdU positive nuclei increased 48 h after injection. Signs of nodule regression (apoptotic bodies, lipofuscin-like deposits) and a decrease in the proportion of BrdU positive nuclei were found at 96 h. In addition, the area of renal hemocyte islets was significantly increased 96 h after injection. Nevertheless, the high complexity of the small vascular chambers that constitute the lung's respiratory lamina would also facilitate hemocyte-antigen contacts, required to elicit cellular aggregation, and hence, nodulation. To our knowledge, this paper includes the first quantitative indication of hemocyte proliferation after an immune challenge among Caenogastropoda.
Ramos-Jiliberto, R ;de Espanes, PM ; Franco-Cisterna, M ; Petanidou, T ; Vazquez, DP ; SCIENTIFIC REPORTS ,2018 ,8 ,-.
Plant-pollinator systems are essential for ecosystem functioning, which calls for an understanding of the determinants of their robustness to environmental threats. Previous studies considering such robustness have focused mostly on species' connectivity properties, particularly their degree. We hypothesized that species' phenological attributes are at least as important as degree as determinants of network robustness. To test this, we combined dynamic modeling, computer simulation and analysis of data from 12 plant-pollinator networks with detailed information of topology of interactions as well as species' phenology of plant flowering and pollinator emergence. We found that phenological attributes are strong determinants of network robustness, a result consistent across the networks studied. Plant species persistence was most sensitive to increased larval mortality of pollinators that start earlier or finish later in the season. Pollinator persistence was especially sensitive to decreased visitation rates and increased larval mortality of specialists. Our findings suggest that seasonality of climatic events and anthropic impacts such as the release of pollutants is critical for the future integrity of terrestrial biodiversity.
Monferran, MD ;D'Angelo, JA ; Cabaleri, NG ; Gallego, OF ; Garban, G ; JOURNAL OF PALEONTOLOGY ,2018 ,92 ,1054 -1065 .
Spinicaudatans ('clam shrimps') are small branchiopod crustaceans enclosed in a chitinous bivalved carapace that is often the only preserved element in the fossil record. However, few studies have analyzed the preservation of these carapaces, which have been found in continental facies from the Devonian to the present. The aim of this study was to contribute to a better understanding of the chemical preservation of fossil spinicaudatan carapaces, and it focused on spinicaudatan carapaces of the Cariadon Asfalto Formation from the Jurassic of Argentina. Semiquantitative energy-dispersive X-ray spectrometry (EDS) analysis provided elemental composition data that were interpreted using principal component analysis (PCA). The results showed a complex chemical mode of preservation for spinicaudatan carapaces. In some parts, EDS spectra of the specimens exhibit peaks of calcium, phosphorous, aluminum, and fluorine, representing the retention of original carapace material with some diagenetic recrystallization. Certain zones of the carapace show low-intensity peaks of the elements mentioned, while silicon and oxygen peaks (from the rock matrix) become the dominant spectral signals. These modes of preservation modify the interpretations and observations of the ornamentation of the carapace, which are used as taxonomic features. Our results suggest that specific diagenetic processes play a fundamental role in the preservation of spinicaudatans.
Aguilera, MO ;Delgui, LR ; Romano, PS ; Colombo, MI ; CELLS ,2018 ,7 ,-.
Multiple tissues and systems in the organism undergo modifications during aging due to an accumulation of damaged proteins, lipids, and genetic material. To counteract this process, the cells are equipped with specific mechanisms, such as autophagy and senescence. Particularly, the immune system undergoes a process called immunosenescence, giving rise to a chronic inflammatory status of the organism, with a decreased ability to counteract antigens. The obvious result of this process is a reduced defence capacity. Currently, there is evidence that some pathogens are able to accelerate the immunosenescence process for their own benefit. Although to date numerous reports show the autophagy-senescence relationship, or the connection between pathogens with autophagy or senescence, the link between the three actors remains unexplored. In this review, we have summarized current knowledge about important issues related to aging, senescence, and autophagy.
D'Angelo, JA ;Zodrow, EL ; INTERNATIONAL JOURNAL OF COAL GEOLOGY ,2018 ,198 ,63 -76 .
A theoretical biomechanical model is proposed for the largest known 650 mm-long frond segment Neuropteris ovata var. simonii (Medullosales, Pennsylvanian, Sydney Coalfield, Canada). The study procedure includes, amongst others, a novel methodology for calculating density of fossil pinnules and rachides. This, in conjunction with the trait relationships and mathematical models that linked density and material/structural properties established for modern plant-leaf tissues, permits the estimation of tensile strength, tensile modulus of elasticity, flexural stiffness, and leaf mass per area. Results suggest that, theoretically, (a) the living frond invested a considerable amount of resources for the construction of metabolically expensive, hard, tough, and resistant pinnule and rachial tissues, which were "made to last", and (b) were used as part of a combination of strategies that increased the plant's biomechanical stability. This translated in resistance to damage during the application of external loads such as those exerted by strong winds or tropical storms. High leaf mass per area (dry-mass investment) of pinnules and rachial tissues points to a slow photosynthetic return that was sustained for long periods of time (long leaf lifespan). The latter possibly indicates a plant adaptation to wet, levee-top habitats, which were characterized by nutrient-deficient soils exposed to intensive solar irradiation. The 3D, chemistry based model of the N. ovata specimen provided new insights into the hitherto poorly-known biomechanical and related traits of this iconic medullosalean plant that inhabited Pennsylvanian wetlands. Other implications of using our chemistry-based methodology include the estimation of (i) frond size and shape (plant reconstructions), (ii) plant ecophysiological adaptations to different wetland environments, and (iii) plant phylogenetic and ontogenetic adaptations.
Troncoso, M ;Bannoud, N ; Carvelli, L ; Asensio, J ; Seltzer, A ; Sosa, MA ; BIOLOGY OPEN ,2018 ,7 ,-.
Neuronal excitotoxicity induced by glutamatergic receptor overstimulation contributes to brain damage. Recent studies have shown that lysosomal membrane permeabilization (LMP) is involved in ischemia-associated neuronal death. In this study we evaluated the effect of neonatal hypoxia-ischemia (HI), as a model of excitotoxicity, on the lysosomal integrity throughout the distribution of the lysosomal proteins cathepsin D and prosaposin. Rat pups (7 days old) of the Wistar Kyoto strain were submitted to HI and they were euthanized 4 days after treatment and the cerebral cortex (Cx) and hippocampus (HIP) were processed for immunohistochemistry or immunoblotting. Treatment induced an increase of gliosis and also a redistribution of both prosaposin and cathepsin D (as intermediate and mature forms), into the cytosol of the HIP and Cx. In addition, HI induced a decrease of LAMP-1 in the membranous fraction and the appearance of a reactive band to anti-LAMP-1 in the cytosolic fraction, suggesting a cleavage of this protein. From these results, we propose that the abnormal release of Cat D and PSAP to the cytosol is triggered as a result of LAMP-1 cleavage in HI animals, which leads to cell damage. This could be a common mechanism in pathological conditions that compromises neuronal survival and brain function.
Giraud-Billoud, M ;Castro-Vazquez, A ; Campoy-Diaz, AD ; Giuffrida, PM ; Vega, IA ; COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY B-BIOCHEMISTRY & MOLECULAR ,2018 ,224 ,129 -137 .
Pomacea canaliculata may serve as a model organism for comparative studies of oxidative damage and antioxidant defenses in active, hibernating and arousing snails. Oxidative damage (as TBARS), free radical scavenging capacity (as ABTS(+) oxidation), uric acid (UA) and glutathione (GSH) concentrations, activities of superoxide dismutase (SOD) and catalase (CAT), and the protein expression levels of heat shock proteins (Hsp70, Hsc70, Hsp90) were studied in digestive gland, kidney and foot. Tissue TBARS of hibernating snails (45 days) was higher than active snails. Hibernation produced an increase of ABTS(+) in digestive gland, probably because of the sustained antioxidant defenses (UA and/or GSH and SOD levels). Kidney protection during the activity hibernation cycle seemed provided by increased UA concentrations. TSARS in the foot remained high 30 min after arousal with no changes in ABTS, but this tissue increased ABTS oxidation at 24 h to expenses increased UA and decreased GSH levels, and with no changes in SOD and CAT activities. The level of Hsp70 in kidney showed no changes throughout the activity-hibernation cycle but it increased in the foot after hibernation. The tissue levels of Hsp90 in snails hibernating were higher than active snails and returned to baseline 24 h after arousal. Results showed that chronic cooling produces a significant oxidative damage in three studied tissues and that these tissue damages are overcome quickly (between 30 min to 24 h) with fluctuations in different antioxidant defenses (UA, GSH, CAT) and heat shock proteins (Hsp70 and Hsp90).
Kaluza, P ;EPL ,2018 ,123 ,-.
We present a model for the time evolution of network architectures based on dynamical systems. We show that the evolution of the existence of a connection in a network can be described as a stochastic non-Markovian telegraphic signal (NMTS). Such signal is formulated in two ways: as an algorithm and as the result of a system of differential equations. The autonomous learning conjecture (Kaluza P. and Mikhailov A.S., Phys. Rev. E, 90 (2014) 030901(R)) is implemented in the proposed dynamics. As a result, we construct self-organizing dynamical systems (networks) able to modify their structures in order to learn prescribed target functionalities. This theory is applied to two systems: the flow processing networks with time-programmed responses, and a system of first-order chemical reactions. In both cases, we show examples of the evolution and a statistical analysis of the obtained functional networks with respect to the model parameters. Copyright (C) EPLA, 2018
Riga, BJG ;Mannion, PD ; Poropat, SF ; David, LDO ; Coria, JP ; ZOOLOGICAL JOURNAL OF THE LINNEAN SOCIETY ,2018 ,184 ,136 -181 .
The titanosaurian sauropod dinosaur Mendozasaurus neguyelap is represented by several partial skeletons from a single locality within the Coniacian (lower Upper Cretaceous) Sierra Barrosa Formation in the south of Mendoza Province, northern Neuquen Basin, Argentina. A detailed revision of Mendozasaurus, including previously undocumented remains from the holotype site, allows us to more firmly establish its position within Titanosauria, as well as enabling an emended diagnosis of this taxon. Autapomorphies include: (1) middle and posterior cervical vertebrae with tall and transversely expanded neural spines that are wider than the centra, formed laterally by spinodiapophy-seal laminae that are not connected with the pre- or postzygapophyses; (2) anterior caudal vertebrae (excluding anterior-most) with ventrolateral ridge-like expansion of prezygapophyses; and (3) humerus with divided lateral distal condyle on anterior surface. New remains demonstrate that the presacral vertebrae of Mendozasaurus were not unusually short anteroposteriorly, with this compression instead resulting from taphonomic crushing. Comparative studies of articulated pedes of other taxa allow us to interpret that the pedal formula of Mendozasaurus was 2-2-2-2-0, based on disarticulated bones that form a right hind foot. Mendozasaurus was incorporated into an expanded version of a titanosauriform-focussed phylogenetic data matrix, along with several other contemporaneous South American titanosaurs. The resultant data matrix comprises 84 taxa scored for 423 characters, and our phylogenetic analysis recovers Mendozasaurus as the most basal member of a diverse Lognkosauria, including Futalognkosaurus and the gigantic titanosaurs Argentinosaurus, Notocolossus, Patagotitan and Puertasaurus. Lognkosauria forms a clade with Rinconsauria (Muyelensaurus + Rinconsaurus), with Epachthosaurus and Pitekunsaurus recovered at the base of this grouping. A basal lithostrotian position for this South American clade is well supported, contrasting with some analyses that have placed these taxa outside of Lithostrotia or closer to Saltasauridae. The sister clade to this South American group is composed of an array of near-global taxa and supports the hypothesis that most titanosaurian clades were widespread by the Early-middle Cretaceous.
Nasif, D ;Campoy, E ; Laurito, S ; Branham, R ; Urrutia, G ; Roque, M ; Branham, MT ; CLINICAL EPIGENETICS ,2018 ,10 ,-.
Background: Inhibitor of differentiation protein 4 (ID4) is a dominant negative regulator of the basic helix-loophelix (bHLH) family of transcription factors. During tumorigenesis, ID4 may act as a tumor suppressor or as an oncogene in different tumor types. However, the role of ID4 in breast cancer is not clear where both an oncogenic and a tumor suppressor function have been attributed. Here, we hypothesize that ID4 behaves as both, but its role in breast differs according to the estrogen receptor (ER) status of the tumor.
Marti, JML ;English, NJ ; Del Popolo, MG ; PHYSICAL CHEMISTRY CHEMICAL PHYSICS ,2018 ,20 ,19234 -19239 .
Phase segregation of multicomponent lipid bilayers leads to, under phase-coexistence conditions, domain formation, featuring delimitation by essentially one-dimensional borders. (Micro-)phase segregation of bilayers is proposed to influence the physiological behaviour of cell membranes and provides the driving force for lipid-raft formation. Experiments show a maximum in the electrical-conductivity of membranes at the phase-transition point, which has been conjectured to arise from border-nucleated transmembrane-conducting defects or pores. However, recent electroporation experiments on phase-segregated bilayers demonstrate electro-pore detection in the liquid disordered phase (L-d), wherein they diffuse over macroscopic periods without absorption into the liquid ordered phase (L-o). Here, we scrutinise transmembrane-pore formation via molecular dynamics simulations on a multicomponent phase-segregated bilayer. We find that pores created in L-o domains always migrate spontaneously to the L-d phase, via recruitment' of unsaturated lipids to the pore's rim to transport the pore to the fluid phase under a large stress-field driving force. Once in L-d domains, pores migrate towards their centre, never returning or pinning to L-o. These findings are explained by thermodynamics. By comparing the free-energy cost for creating pores in the bulk of L-d and L-o membranes, and in the phase-segregated system, we show that it is always more energetically tractable to create pores in L-d domains, independent of the pore size.
Moguilner, S ;Garcia, AM ; Mikulan, E ; Hesse, E ; Garcia-Cordero, I ; Melloni, M ; Cervetto, S ; Serrano, C ; Herrera, E ; Reyes, P ; Matallana, D ; Manes, F ; Ibanez, A ; Sedeno, L ; SCIENTIFIC REPORTS ,2018 ,8 ,-.
The search for biomarkers of neurodegenerative diseases via fMRI functional connectivity (FC) research has yielded inconsistent results. Yet, most FC studies are blind to non-linear brain dynamics. To circumvent this limitation, we developed a "weighted Symbolic Dependence Metric" (wSDM) measure. Using symbolic transforms, we factor in local and global temporal features of the BOLD signal to weigh a robust copula-based dependence measure by symbolic similarity, capturing both linear and non-linear associations. We compared this measure with a linear connectivity metric (Pearson's R) in its capacity to identify patients with behavioral variant frontotemporal dementia (bvFTD) and controls based on resting-state data. We recruited participants from two international centers with different MRI recordings to assess the consistency of our measure across heterogeneous conditions. First, a seed-analysis comparison of the salience network (a specific target of bvFTD) and the default-mode network (as a complementary control) between patients and controls showed that wSDM yields better identification of resting-state networks. Moreover, machine learning analysis revealed that wSDM yielded higher classification accuracy. These results were consistent across centers, highlighting their robustness despite heterogeneous conditions. Our findings underscore the potential of wSDM to assess fMRI-derived FC data, and to identify sensitive biomarkers in bvFTD.
Diaz, MAL ;D'Angelo, JA ; Del Fueyo, GM ; Zodrow, EL ; PALAIOS ,2018 ,33 ,323 -337 .
The present study is a holistic approach to the relationship between volcaniclastic host rock characteristics and the fossilization processes of short leafy coniferous branches of Squamastrobus tigrensis, preserved as fossilized-cuticles (Lower Cretaceous, Baquero Group, Patagonia, Argentina). The question of diagenetic influences of Aptian volcaniclastic sedimentation on preservation chemistry and taphonomic processes is addressed. Whereas infrared spectroscopy provided chemical information on the leaves, vitrinite reflectance and complementary thermal indicators provided data on the thermal maturity of the dispersed organic matter in the host rock. Three sample types were analyzed: fossilized-cuticle, macerated fossilized-cuticle (by infrared spectroscopy), and associated organic host rock matter (by light microscopy). Results clearly show chemical variability between, and within the fossilized-cuticle and cuticle, as well as a similarity to type I/II kerogen, i.e., high contents of both aliphatic groups and oxygen-containing compounds. Combined with the lower maturity of the host rock, the importance of the depositional environment during burial and taphonomic conditions that affected the fossilization of S. tigrensis arc summarized in a general fossilization model.
Monge, DA ;Pacini, E ; Mateos, C ; Garino, CG ; COMPUTERS & ELECTRICAL ENGINEERING ,2018 ,69 ,364 -377 .
Cloud Computing is the delivery of on-demand computing resources over the Internet on a pay-per-use basis and is very useful to execute scientific experiments such as parameter sweep experiments (PSEs). When PSEs are executed it is important to reduce both the makespan and monetary cost. We propose a novel tri-objective formulation for the PSEs autoscaling problem considering unreliable virtual machines (VM) pursuing the minimization of makespan, monetary cost and probability of failures. We also propose a new autoscaler based on the Non-dominated Sorting Genetic Algorithm II able to automatically determine the right amount for each type of VM and pricing scheme, as well as the bid prices for the spot instances. Experiments show that the proposed autoscaler achieves great improvements in terms of makespan and cost when it is compared against Scaling First and Spot Instances Aware Autoscaling. (C) 2017 Elsevier Ltd. All rights reserved.
Fiorentini, EF ;Escudero, LB ; Wuilloud, RG ; ANALYTICAL AND BIOANALYTICAL CHEMISTRY ,2018 ,410 ,4715 -4723 .
A simple, highly efficient, batch, and centrifuge-less dispersive liquid-liquid microextraction method based on a magnetic ionic liquid (MIL-DLLME) and electrothermal atomic absorption spectrometry (ETAAS) detection was developed for ultra-trace Cd determination in honey. Initially, Cd(II) was chelated with ammonium diethyldithiophosphate (DDTP) at pH 0.5 followed by its extraction with the MIL trihexyl(tetradecyl)phosphonium tetrachloroferrate(III) ([P-6,P-6,P-6,P-14]FeCl4) and acetonitrile as dispersant. The MIL phase containing the analyte was separated from the aqueous phase using only a magnet. A back-extraction procedure was applied to recover Cd from the MIL phase using diluted HNO3 and this solution was directly injected into the graphite furnace of ETAAS instrument. An extraction efficiency of 93% and a sensitivity enhancement factor of 112 were obtained under optimal experimental conditions. The detection limit (LOD) was 0.4 ng L-1 Cd, while the relative standard deviation (RSD) was 3.8% (at 2 mu g L-1 Cd and n = 10), calculated from the peak height of absorbance signals. This work reports the first application of the MIL [P-6,P-6,P-6,P-14]FeCl4 along with the DLLME technique for the successful determination of Cd at trace levels in different honey samples.
Perez, MB ;Maniero, MA ; Londonio, A ; Smichowski, P ; Wuilloud, RG ; JOURNAL OF FOOD COMPOSITION AND ANALYSIS ,2018 ,70 ,54 -62 .
The effect of traditional thermal treatments, normally applied during cooking practices, on the stability of Se amino acids and Se-proteins present in Se-enriched garlic was studied. Five heat treatments including, convection oven (180 degrees C, 10 min), boiling (100 degrees C, 10 min), microwave oven (800 W, 3 min), steaming (10 min) and stir-frying (180 degrees C, 3 min) were assayed. Modifications on the molecular weight fractions profiles of protein extracts were evaluated by size exclusion chromatography with UV-visible and inductively coupled plasma mass spectrometry (ICP-MS) detection using a 0.05 M Tris(hidroxymethyl)aminomethane solution at pH 7.3 as the mobile phase. Possible modifications of Se-amino acids were evaluated by anion exchange chromatography (AEC), with a 30 mM Na2HPO4 solution (pH 6) as the mobile phase, coupled to ICP-MS after enzymatic hydrolysis. SEC chromatograms showed the incorporation of Se to high (7 kDa) and low molecular weight fractions (2-4 kDa) while AEC chromatograms showed mostly the presence of Se-methylselenocysteine. However, it could be observed that heat treatments significantly affect this important Se-amino acid.
Cianci, N ;Ottina, M ; JOURNAL OF COMBINATORIAL THEORY SERIES A ,2018 ,157 ,120 -161 .
We prove that the fundamental group and the integral homology groups of a poset with fewer than 13 points are torsion free, settling a conjecture of Hardie, Vermeulen and Witbooi and answering a question of Barmak. In addition, we prove that if a poset has fewer than 16 points then the geometric realization of its order complex can not be homotopy equivalent to either the torus or the Klein bottle, answering another open question. Furthermore, we find all the posets of 16 points (resp. of 13 points) such that the geometric realizations of their order complexes are homotopy equivalent to either the torus or the Klein bottle (resp. to the real projective plane). (C) 2018 Elsevier Inc. All rights reserved.
Valencia, FJ ;Hernandez-Vazquez, EE ; Bringa, EM ; Moran-Lopez, JL ; Rogan, J ; Gonzalez, RI ; Munoz, F ; PHYSICAL CHEMISTRY CHEMICAL PHYSICS ,2018 ,20 ,16347 -16353 .
We studied the soft landing of Ni atoms on a previously damaged graphene sheet by means of molecular dynamics simulations. We found a monotonic decrease of the cluster frequency as a function of its size, but few big clusters comprise an appreciable fraction of the total number of Ni atoms. The aggregation of Ni atoms is also modeled by means of a simple phenomenological model. The results are in clear contrast with the case of hard or energetic landing of metal atoms, where there is a tendency to form mono-disperse metal clusters. This behavior is attributed to the high diffusion of unattached Ni atoms, together with vacancies acting as capture centers. The findings of this work show that a simple study of the energetics of the system is not enough in the soft landing regime, where it is unavoidable to also consider the growth process of metal clusters.
Lujan, AL ;Croci, DO ; Tudelaa, JAG ; Losinno, AD ; Cagnoni, AJ ; Marino, KV ; Damiani, MT ; Rabinovich, GA ; PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF ,2018 ,115 ,E6000 -E6009 .
Chlamydia trachomatis (Ct) constitutes the most prevalent sexually transmitted bacterium worldwide. Chlamydial infections can lead to severe clinical sequelae including pelvic inflammatory disease, ectopic pregnancy, and tuba! infertility. As an obligate intracellular pathogen, Ct has evolved multiple strategies to promote adhesion and invasion of host cells, including those involving both bacterial and host glycans. Here, we show that galectin-1 (Gall), an endogenous lectin widely expressed in female and male genital tracts, promotes Ct infection. Through glycosylation-dependent mechanisms involving recognition of bacterial glycoproteins and N-glycosylated host cell receptors, Gall enhanced Ct attachment to cervical epithelial cells. Exposure to Gall, mainly in its dimeric form, facilitated bacterial entry and increased the number of infected cells by favoring Ct-Ct and Ct-host cell interactions. These effects were substantiated in vivo in mice lacking Gall or complex 01-6-branched Nglycans. Thus, disrupting Gall-N-glycan interactions may limit the severity of chlamydial infection by inhibiting bacterial invasion of host cells.
Klug, J ;Triguero, C ; Del Popolo, MG ; Tribello, GA ; JOURNAL OF PHYSICAL CHEMISTRY B ,2018 ,122 ,6417 -6422 .
A reaction coordinate that can be used when investigating binding to dynamical surfaces with molecular dynamics is introduced. This coordinate measures the distance between the adsorbate and an isocontour in a density field. Furthermore, the coordinate is continuous so simulation biases that are a function of this coordinate can be added to the Hamiltonian to increase the rate of adsorption/desorption. The efficacy of this new coordinates is demonstrated by performing metadynamics simulations to measure the strength with which a hydrophilic nanoparticle binds to a lipid bilayer. An investigation of the binding mechanism that is performed using the coordinate demonstrates that the lipid bilayer undergoes a series of concerted changes in structure as the nanoparticle binds.
Hierro, R ;Steiner, AK ; de la Torre, A ; Alexander, P ; Llamedo, P ; Cremades, P ; ATMOSPHERIC MEASUREMENT TECHNIQUES ,2018 ,11 ,3523 -3539 .
Gravity waves (GWs) and convective systems play a fundamental role in atmospheric circulation, weather, and climate. Two usual main sources of GWs are orographic effects triggering mountain waves and convective activity. In addition, GW generation by fronts and geostrophic adjustment must also be considered. The utility of Global Positioning System (GPS) radio occultation (RO) observations for the detection of convective systems is tested. A collocation database between RO events and convective systems over subtropical to midlatitude mountain regions close to the Alps and Andes is built. From the observation of large-amplitude GW structures in the absence of jets and fronts, subsets of RO profiles are sampled. A representative case study among those considered at each region is selected and analyzed. The case studies are investigated using mesoscale Weather Research and Forecasting (WRF) simulations, ERA-Interim reanalysis data, and measured RO temperature profiles. The absence of fronts or jets during both case studies reveals similar relevant GW features (main parameters, generation, and propagation). Orographic and convective activity generates the observed GWs. Mountain waves above the Alps reach higher altitudes than close to the Andes. In the Andes case, a critical layer prevents the propagation of GW packets up to stratospheric heights. The case studies are selected also because they illustrate how the observational window for GW observations through RO profiles admits a misleading interpretation of structures at different altitude ranges. From recent results, the distortion introduced in the measured atmospheric vertical wavelengths by one of the RO events is discussed as an illustration. In the analysis, both the elevation angle of the sounding path (line of tangent points) and the gravity wave aspect ratio estimated from the simulations and the line of sight are taken into account. In both case studies, a considerable distortion, over- and underestimation of the vertical wavelengths measured by RO, may be expected.
Ruestes, CJ ;Anders, C ; Bringa, EM ; Urbassek, HM ; JOURNAL OF APPLIED PHYSICS ,2018 ,123 ,-.
Irradiation by light ions may change the mechanical properties of nanofoams. Using molecular-dynamics simulation, we study the effect of irradiating a Au foam (porosity, 50%, and ligament diameter, 3 nm) with heavy ions: here, 10 keV Au ions up to a dose of 4 x 10(16) m(-2). We demonstrate that in consequence, the ligament morphology changes in the irradiated region, caused by local melting. The changes in mechanical properties are monitored by simulated nanoindentation tests. We find that the foam hardness is only around 1/3 of the hardness of a bulk Au crystal. Irradiation increases the hardness of the foam by around 10% in the central irradiated area. The plastic zone extends to only 1.5 a(c), where a(c) denotes the contact radius; this value is unchanged under irradiation. The hardness increase after irradiation is attributed to two concurring effects. To begin with, irradiation induces melting and annealing of the ligaments, leading to their coarsening and alleviating surface stress, which in turn increases the dislocation nucleation threshold. In addition, irradiation introduces a stacking fault forest that acts as an obstacle to dislocation motion. Published by AIP Publishing.
Gimenez, MC ;Zanetti, FA ; Terebiznik, MR ; Colombo, MI ; Delgui, LR ; JOURNAL OF VIROLOGY ,2018 ,92 ,-.
Birnaviruses are unconventional members of the group of double-stranded RNA (dsRNA) viruses that are characterized by the lack of a transcriptionally active inner core. Instead, the birnaviral particles organize their genome in ribonucleoprotein complexes (RNPs) composed by dsRNA segments, the dsRNA-binding VP3 protein, and the virally encoded RNA-dependent RNA polymerase (RdRp). This and other structural features suggest that birnaviruses may follow a completely different replication program from that followed by members of the Reoviridae family, supporting the hypothesis that birnaviruses are the evolutionary link between single-stranded positive RNA (+ssRNA) and dsRNA viruses. Here we demonstrate that infectious bursal disease virus (IBDV), a prototypical member of the Birnaviridae family, hijacks endosomal membranes of infected cells through the interaction of a viral protein, VP3, with the phospholipids on the cytosolic leaflet of these compartments for replication. Employing a mutagenesis approach, we demonstrated that VP3 domain PATCH 2 (P2) mediates the association of VP3 with the endosomal membranes. To determine the role of VP3 P2 in the context of the virus replication cycle, we used avian cells stably overexpressing VP3 P2 for IBDV infection. Importantly, the intra- and extracellular virus yields, as well as the intracellular levels of VP2 viral capsid protein, were significantly diminished in cells stably overexpressing VP3 P2. Together, our results indicate that the association of VP3 with endosomes has a relevant role in the IBDV replication cycle. This report provides direct experimental evidence for membranous compartments such as endosomes being required by a dsRNA virus for its replication. The results also support the previously proposed role of birnaviruses as an evolutionary link between +ssRNA and dsRNA viruses. IMPORTANCE Infectious bursal disease (IBD; also called Gumboro disease) is an acute, highly contagious immunosuppressive disease that affects young chickens and spreads worldwide. The etiological agent of IBD is infectious bursal disease virus (IBDV). This virus destroys the central immune organ (bursa of Fabricius), resulting in immunosuppression and reduced responses of chickens to vaccines, which increase their susceptibility to other pathogens. IBDV is a member of Birnaviridae family, which comprises unconventional members of dsRNA viruses, whose replication strategy has been scarcely studied. In this report we show that IBDV hijacks the endosomes of the infected cells for establishing viral replication complexes via the association of the ribonucleoprotein complex component VP3 with the phospholipids in the cytosolic leaflet of endosomal membranes. We show that this interaction is mediated by the VP3 PATCH 2 domain and demonstrate its relevant role in the context of viral infection.
Marsh, EJ ;Bruno, MC ; Fritz, SC ; Baker, P ; Capriles, JM ; Hastorf, CA ; RADIOCARBON ,2018 ,60 ,925 -940 .
Because the C-14 calibration curves IntCal and SHCal are based on data from temperate latitudes, it remains unclear which curve is more suitable for archaeological and paleoenvironmental records from tropical South America. A review of climate dynamics reveals a significant influx of Northern Hemisphere air masses and moisture over a substantial part of the continent during the South American Summer Monsoon (SASM). Areas affected by the SASM receive unknown amounts of input from both hemispheres, where an argument could be made for either curve. Until localized tree-ring data can resolve this, we suggest using a mixed calibration curve, which accounts for inputs from both hemispheres, as a third calibration option. We present a calibration example from a crucial period of environmental and cultural change in the southern Lake Titicaca. Given our current lack of data on past C-14 variation in South America, our calibrations and chronologies will likely change in the future. We hope this paper spurs new research into this topic and encourages researchers to make an informed and explicit choice of which curve to use, which is particularly relevant in research on past human-environmental relationships.
Edera, AA ;Gandini, CL ; Sanchez-Puerta, MV ; PLANT MOLECULAR BIOLOGY ,2018 ,97 ,215 -231 .
Our understanding of the dynamic and evolution of RNA editing in angiosperms is in part limited by the few editing sites identified to date. This study identified 10,217 editing sites from 17 diverse angiosperms. Our analyses confirmed the universality of certain features of RNA editing, and offer new evidence behind the loss of editing sites in angiosperms.
Valdovinos, FS ;Berlow, EL ; de Espanes, PM ; Ramos-Jiliberto, R ; Vazquez, DP ; Martinez, ND ; NATURE COMMUNICATIONS ,2018 ,9 ,-.
Species invasions constitute a major and poorly understood threat to plant-pollinator systems. General theory predicting which factors drive species invasion success and subsequent effects on native ecosystems is particularly lacking. We address this problem using a consumer-resource model of adaptive behavior and population dynamics to evaluate the invasion success of alien pollinators into plant-pollinator networks and their impact on native species. We introduce pollinator species with different foraging traits into network models with different levels of species richness, connectance, and nestedness. Among 31 factors tested, including network and alien properties, we find that aliens with high foraging efficiency are the most successful invaders. Networks exhibiting high alien-native diet overlap, fraction of alien-visited plant species, most-generalist plant connectivity, and number of specialist pollinator species are the most impacted by invaders. Our results mimic several disparate observations conducted in the field and potentially elucidate the mechanisms responsible for their variability.
Wales, PA ;Salawitch, RJ ; Nicely, JM ; Anderson, DC ; Canty, TP ; Baidar, S ; Dix, B ; Koenig, TK ; Volkamer, R ; Chen, DX ; Huey, LG ; Tanner, DJ ; Cuevas, CA ; Fernandez, RP ; Kinnison, DE ; Lamarque, JF ; Saiz-Lopez, A ; Atlas, EL ; Hall, SR ; Navarro, MA ; Pan, LL ; Schauffler, SM ; Stell, M ; Tilmes, S ; Ullmann, K ; Weinheimer, AJ ; Akiyoshi, H ; Chipperfield, MP ; Deushi, M ; Dhomse, SS ; Feng, WH ; Graf, P ; Hossaini, R ; Jockel, P ; Mancini, E ; Michou, M ; Morgenstern, O ; Oman, LD ; Pitari, G ; Plummer, DA ; Revell, LE ; Rozanov, E ; Saint-Martin, D ; Schofield, R ; Stenke, A ; Stone, KA ; Visioni, D ; Yamashita, Y ; Zeng, G ; JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES ,2018 ,123 ,5690 -5719 .
We quantify the stratospheric injection of brominated very short-lived substances (VSLS) based on aircraft observations acquired in winter 2014 above the Tropical Western Pacific during the CONvective TRansport of Active Species in the Tropics (CONTRAST) and the Airborne Tropical TRopopause EXperiment (ATTREX) campaigns. The overall contribution of VSLS to stratospheric bromine was determined to be 5.02.1ppt, in agreement with the 53ppt estimate provided in the 2014 World Meteorological Organization (WMO) Ozone Assessment report (WMO 2014), but with lower uncertainty. Measurements of organic bromine compounds, including VSLS, were analyzed using CFC-11 as a reference stratospheric tracer. From this analysis, 2.90.6ppt of bromine enters the stratosphere via organic source gas injection of VSLS. This value is two times the mean bromine content of VSLS measured at the tropical tropopause, for regions outside of the Tropical Western Pacific, summarized in WMO 2014. A photochemical box model, constrained to CONTRAST observations, was used to estimate inorganic bromine from measurements of BrO collected by two instruments. The analysis indicates that 2.12.1ppt of bromine enters the stratosphere via inorganic product gas injection. We also examine the representation of brominated VSLS within 14 global models that participated in the Chemistry-Climate Model Initiative. The representation of stratospheric bromine in these models generally lies within the range of our empirical estimate. Models that include explicit representations of VSLS compare better with bromine observations in the lower stratosphere than models that utilize longer-lived chemicals as a surrogate for VSLS.
Fernandez, A ;Munoz, A ; Gonzalez-Reyes, A ; Aguilera-Betti, I ; Toledo, I ; Puchi, P ; Sauchyn, D ; Crespo, S ; Frene, C ; Mundo, I ; Gonzalez, M ; Vignola, R ; HYDROLOGY AND EARTH SYSTEM SCIENCES ,2018 ,22 ,2921 -2935 .
Streamflow in south-central Chile (SCC, similar to 3742 degrees S) is vital for agriculture, forestry production, hydroelectricity, and human consumption. Recent drought episodes have generated hydrological deficits with damaging effects on these activities. This region is projected to undergo major reductions in water availability, concomitant with projected increases in water demand. However, the lack of long-term records hampers the development of accurate estimations of natural variability and trends. In order to provide more information on long-term streamflow variability and trends in SCC, here we report findings of an analysis of instrumental records and a tree-ring reconstruction of the summer streamflow of the Rio Imperial (similar to 37 degrees 40' S-38 degrees 50' S). This is the first reconstruction in Chile targeted at this season. Results from the instrumental streamflow record (similar to 1940 onwards) indicated that the hydrological regime is fundamentally pluvial with a small snowmelt contribution during spring, and evidenced a decreasing trend, both for the summer and the full annual record. The reconstruction showed that streamflow below the average characterized the post-1980 period, with more frequent, but not more intense, drought episodes. We additionally found that the recent positive phase of the Southern Annular Mode has significantly influenced streamflow. These findings agree with previous studies, suggesting a robust regional signal and a shift to a new hydrological scenario. In this paper, we also discuss implications of these results for water managers and stakeholders; we provide rationale and examples that support the need for the incorporation of tree-ring reconstructions into water resources management.
Chillo, V ;Vazquez, DP ; Amoroso, MM ; Bennett, EM ; FUNCTIONAL ECOLOGY ,2018 ,32 ,1390 -1399 .
1. Land-use change is known to affect biodiversity, and there is increasing concern regarding how these changes may impact the provision of ecosystem services. Although functional composition (diversity and identity) could influence ecosystem properties and services at the community level, there is little quantitative understanding of these relationships in the field. Here, we evaluate the direct and indirect effects (through ecosystem properties) of biodiversity on the provision of multiple ecosystem services in native mixed forest in north-west Patagonia, and how land-use intensity influences these relationships.
Reyes, PN ;Valencia, FJ ; Vega, H ; Ruestes, C ; Rogan, J ; Valdivia, JA ; Kiwi, M ; INORGANIC CHEMISTRY FRONTIERS ,2018 ,5 ,1139 -1144 .
Hollow nanoparticles (hNPs) are of interest because their large cavities and small thickness give rise to a large surface to volume ratio. However, in general they are not in equilibrium and far from their global energy minimum, which often makes them unstable against perturbations. In fact, a temperature increase can induce a structural collapse into a nanoparticle, and consequently a loss of their unique properties. This problem has been studied by means of molecular dynamics (MD) simulations, but without emphasis on the speed of the temperature increase. Here we explore how the temperature variation, and the rate at which it is varied in MD simulations, determines the final conformation of the hNPs. In particular, we show how different temperature ramps determine the final shape of Pt hNPs that initially have an external radius between 0.7 and 24 nm, and an internal radius between 0.19 and 2.4 nm. In addition, we also perform the simulations of other similar metals like Ag and Au. Our results indicate that the temperature ramp strongly modifies the final hNP shape, even at ambient temperature. In fact, a rapid temperature increase leads to the formation of stacking faults and twin boundaries which are not generated by a slower temperature increase. Quantitative criteria are established and they indicate that the stacking fault energy is the dominant parameter.
Grijalba, AC ;Quintas, PY ; Fiorentini, EF ; Wuilloud, RG ; JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY ,2018 ,33 ,822 -834 .
Different ionic liquids (ILs) were studied in this work as mobile phase modifiers for the separation and determination of Hg2+, methylmercury (CH3Hg+) and ethylmercury (C2H5Hg+) species by reversed-phase high-performance liquid chromatography coupled to UV-cold vapor atomic fluorescence spectrometry (RP-HPLC-UV-CV-AFS). Several parameters influencing the chromatographic separation of Hg species, such as pH, sodium chloride concentration, organic solvent concentration, as well as chemical structure and concentration of ILs were evaluated. After a careful optimization, the separation of Hg species was achieved within 12 min using a C-18 column and a gradient developed by mixing methanol and a solution composed of 0.4% (v/v) 1-octyl-3-methylimidazolium chloride [C(8)mim]Cl, 100 mmol L-1 NaCl and 20 mmol L-1 buffer citric acid/citrate at pH 2.0. In addition, a multivariate methodology was applied to optimize the parameters involved in UV-CV-AFS detection of Hg species. The proposed method allowed the separation of inorganic and organic Hg species in a single chromatographic run. The limits of detection obtained for Hg species were in the range of 0.05-0.11 mu g L-1. The usefulness of the proposed method was demonstrated by performing Hg speciation analysis in highly complex samples, such as seafood, yeast and garlic, obtaining accurate and precise results in all cases.
Pinna, EG ;Barbosa, LI ; Suarez, DS ; Rodriguez, MH ; INDIAN JOURNAL OF CHEMICAL TECHNOLOGY ,2018 ,25 ,287 -293 .
The kinetics mechanism on the dissolution of metakaolin by hydrofluoric acid has been studied. The effects of temperature, reaction time, and stirring speed have been examined. Experimental results show that reaction rate increases with both temperature and reaction time. The global process of metakaolin dissolution with HF is characterized with an apparent activation energy of 21.096 kcal/mol, which indicates that the reaction rate is mainly controlled by the chemical stage. Experimental data fitted the sequential nucleation and growth model.
Sanabria, E ;Quiroga, L ; Vergara, C ; Banchig, M ; Rodriguez, C ; Ontivero, E ; JOURNAL OF THERMAL BIOLOGY ,2018 ,74 ,195 -200 .
Rhinella spinulosa is distributed from Peru to Argentina (from 1200 to 5000 m elevation), inhabiting arid mountain valleys of the Andes, characterized by salty soils. The variations in soil salinity, caused by high evapotranspiration of water, can create an osmotic constraint and high thermal oscillations for metamorphsed Andean toad (R. spinulosa), affecting their thermoregulation and extreme thermal tolerances: We investigated the changes in thermal tolerance parameters (critical thermal maximum and crystallization temperature) of a population of metamorphosed R. spinulosa from the Monte Desert of San Juan, Argentina, under different substrate salinity conditions. Our results suggest that the locomotor performance of metamorphs of R. spinulosa is affected by increasing salinity concentrations in the environment where they develop. On the other hand, the thermal extremes of metamorphs of R. spinulosa also showed changes associated with different salinity conditions. According to other studies on different organisms, the increase of the osmolarity of the internal medium may increase the thermal tolerance of this species. More studies are needed to understand the thermo-osmolar adjustments of the metamorphs of toads to environmental variability.
Ruestes, CJ ;Schwen, D ; Millan, EN ; Aparicio, E ; Bringa, EM ; COMPUTATIONAL MATERIALS SCIENCE ,2018 ,147 ,154 -167 .
Nanoscale metallic foams display mechanical properties which make them attractive for a variety of technological applications. We report simulated nanoindentation tests for a model polycrystalline nanoporous gold structure with 11 nm mean filament diameter and 35 nm average grain size, comparable to foams produced by dealloying. Hardness, plasticity mechanisms, the extension of the plastic zone and the applicability of several scaling laws are discussed. Plasticity occurs at the nodes mainly and is dominated by nucleation of dislocations at the atomic steps of the ligament surfaces, in a dislocation accumulation scenario. Shockley partials, perfect dislocations, Hirth partials, Lomer-Cottrel locks and twins were identified. Grain boundary sliding appears to play a minor role in deformation at the indentation rates used. Several scaling laws are tested and their results and applicability are discussed based on the structural parameters of the foam and the deformation mechanisms identified. (C) 2018 Elsevier B.V. All rights reserved.
Franco, NV ;Cortegoso, V ; Lucero, GF ; Duran, V ; QUATERNARY INTERNATIONAL ,2018 ,473 ,278 -289 .
Storage of artifacts is a common behavior among hunter-gatherers. Archaeologically, caches have been identified in different places and time periods. In this paper, we focus on the discussion of the role of caches recovered along the southern boundary of the Deseado Massif, Argentine Patagonia. Two caches, attributed to the colonization of this environment have been identified. Cache information is integrated into the known archaeological record of this space and spaces nearby and compared with data on raw material availability. In order to evaluate the location of the caches and understand human strategies of landscape utilization during this time period, we use GIS approaches along with available paleoenvironmental data. (C) 2017 Elsevier Ltd and INQUA. All rights reserved.
Rojas-Nunez, J ;Gonzalez, RI ; Bringa, EM ; Allende, S ; Sepulveda, P ; Arancibia-Miranda, N ; Baltazar, SE ; JOURNAL OF PHYSICAL CHEMISTRY C ,2018 ,122 ,8528 -8534 .
Bimetallic nanoparticles (NPs) can be tailored by varying the concentration of their constituent elements, resulting in novel structures and/or configurations, leading to interesting electronic, mechanical, and chemical properties. In this paper, by means of molecular dynamics calculations, we study the morphology of bimetallic FeCu NPs as a function of the Cu concentration. Our results evidence a core shell (CS) structure for low Cu concentrations and a Janus (JN)-like morphology for high Cu content. Structural and energy characterizations were performed to determine the atomic-scale behavior of the NPs. Using a continuous model to describe immiscible components, we obtain a stability transition curve between CS and JN-like structures for several NP sizes and concentrations. Results from both methods are compared with experimental data obtained for NPs with low and high Cu content, evidencing a good agreement among the three approaches.
Rojo, LD ;Mehl, AE ; Zarate, MA ; Garcia, A ; Chivas, AR ; PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY ,2018 ,495 ,205 -213 .
Stable carbon isotopes (delta C-13) and C/N ratios in bulk sediment organic matter were used as indicators of C-3 and C-4 vegetation functional types in a ca. 40-kyr, predominantly alluvial sequence from Arroyo La Estacada (33.5 degrees S, 69 degrees W), in the arid Andean piedmont of central Argentina. Although this sediment sequence has the potential to contribute to the knowledge of past vegetation dynamics through its fossil pollen content, previous palynological studies provided scant information, constrained to a few time windows, because of poor pollen preservation. Stable isotope results for the total organic carbon fraction from three lithostratigraphic sections that span the past 40 kyr show shifts in delta C-13 values associated with changing contributions from C-3 and C-4 plants, suggesting this proxy can detect changes in these photosynthetic pathways, representative of Patagonian (and/or stream margin macrophytes) and Monte phytogeographic units, respectively. Climate and local factors, such as water availability in the basin, are inferred to be the main drivers of vegetation dynamics. The C/N ratios in a few samples show that organic matter sources are algae and/or phytoplankton, not solely C-3 or C-4 vascular plants. The delta C-13 record from Arroyo La Estacada is an example of how isotope geochemistry has overcome difficulties with pollen analysis and provided a reliable tool to investigate past vegetation changes in regions where C-3 and C-4 are differentially distributed. Isotope values during part of the Marine Isotope Stage 3 (MIS 3) and the middle Holocene are attributed to C-3 local floodplain plants, with a little or no contribution from regional terrestrial (Patagonian) vegetation. Late Pleistocene-Holocene palaeosols have a clear C-4 signal of terrestrial dominance, representative of Monte plants, thus, carbon isotope values constrain the early times of MIS 1, particularly where the Pleistocene Holocene transition occurs. A mixture of C-3 and C-4 values during the last 3-4 kyr is indicative of environmental conditions that prevail in the region today.
Cuevas, CA ;Maffezzoli, N ; Corella, JP ; Spolaor, A ; Vallelonga, P ; Kjaer, HA ; Simonsen, M ; Winstrup, M ; Vinther, B ; Horvat, C ; Fernandez, RP ; Kinnison, D ; Lamarque, JF ; Barbante, C ; Saiz-Lopez, A ; NATURE COMMUNICATIONS ,2018 ,9 ,-.
Atmospheric iodine causes tropospheric ozone depletion and aerosol formation, both of which have significant climate impacts, and is an essential dietary element for humans. However, the evolution of atmospheric iodine levels at decadal and centennial scales is unknown. Here, we report iodine concentrations in the RECAP ice-core (coastal East Greenland) to investigate how atmospheric iodine levels in the North Atlantic have evolved over the past 260 years (1750-2011), this being the longest record of atmospheric iodine in the Northern Hemisphere. The levels of iodine tripled from 1950 to 2010. Our results suggest that this increase is driven by anthropogenic ozone pollution and enhanced sub-ice phyto-plankton production associated with the recent thinning of Arctic sea ice. Increasing atmospheric iodine has accelerated ozone loss and has considerably enhanced iodine transport and deposition to the Northern Hemisphere continents. Future climate and anthropogenic forcing may continue to amplify oceanic iodine emissions with potentially significant health and environmental impacts at global scale.
Gojanovich, AD ;Gimenez, MC ; Masone, D ; Rodriguez, TM ; Dewey, RA ; Delgui, LR ; Bustos, DM ; Uhart, M ; FRONTIERS IN CELL AND DEVELOPMENTAL BIOLOGY ,2018 ,6 ,-.
Human Adipose-derived mesenchymal stem/stromal cells (hASCs) are of great interest because of their potential for therapeutic approaches. The method described here covers every single step necessary for hASCs isolation from subcutaneous abdominal adipose tissue, multicolor phenotyping by flow cytometry, and quantitative determination of adipogenic differentiation status by means of lipid droplets (LDs) accumulation, and Western blot analysis. Moreover, to simultaneously analyze both LDs accumulation and cellular proteins localization by fluorescence microscopy, we combined Oil Red O (ORO) staining with immunofluorescence detection. For LDs quantification we wrote a program for automatic ORO-stained digital image processing implemented in Octave, a freely available software package. Our method is based on the use of the traditional low cost neutral lipids dye ORO, which can be imaged both by bright-field and fluorescence microscopy. The utilization of ORO instead of other more expensive lipid-specific dyes, together with the fact that the whole method has been designed employing cost-effective culture reagents (standard culture medium and serum), makes it affordable for tight-budget research laboratories. These may be replaced, if necessary or desired, by defined xeno-free reagents for clinical research and applications.
Duran, VA ;Cortegoso, V ; Barberena, R ; Frigole, C ; Novellino, P ; Lucero, G ; Yebra, L ; Gasco, A ; Winocur, D ; Benitez, A ; Knudson, KJ ; JOURNAL OF ARCHAEOLOGICAL SCIENCE-REPORTS ,2018 ,18 ,668 -678 .
The Andes mountain range is one key physiographic feature of South America with the potential to have acted as a barrier and corridor for human societies. The goal of this paper is to assess from where and how were the highlands utilized during the last 2000 years, which is a key period witnessing the development of productive economies and changes in the organization of mobility. We develop a regional case study focused on the highland wetland Laguna del Diamante (3300 masl), which is a highly productive ecosystem only accessible during summer. This case is based on a multidisciplinary approach combining: a) geochemical characterization of obsidian sources located in the highlands and artifacts; b) isotopic approach to ranges of paleomobility of individuals by means of Sr-87/Sr-86; and c) stylistic study of ceramic assemblages.
Masone, D ;Uhart, M ; Bustos, DM ; JOURNAL OF CHEMICAL THEORY AND COMPUTATION ,2018 ,14 ,2240 -2245 .
Curvature-related processes are of major importance during protein membrane interactions. The illusive simplicity of membrane reshaping masks a complex molecular process crucial for a wide range of biological functions like fusion, endo- and exocytosis, cell division, cytokinesis, and autophagy. To date, no functional expression of a reaction coordinate capable of biasing molecular dynamics simulations to produce membrane curvature has been reported. This represents a major drawback given that the adequate identification of proper collective variables to enhance sampling is fundamental for restrained dynamics techniques. In this work, we present a closed-form equation of a collective variable that induces bending in lipid bilayers in a controlled manner, allowing for straightforward calculation of free energy landscapes of important curvature-related events, using standard methods such as umbrella sampling and metadynamics. As a direct application of the collective variable, we calculate the bending free energies of a ternary lipid bilayer in the presence and the absence of a Bin/Amphiphysin/Rvs domain with an N-terminal amphipathic helix (N-BAR), a well-known peripheral membrane protein that induces curvature.
Campoy-Diaz, AD ;Arribere, MA ; Guevara, SR ; Vega, IA ; CHEMOSPHERE ,2018 ,196 ,196 -205 .
Pomacea canaliculata is a mollusk potentially useful as a biomonitor species of freshwater quality. This work explores the ability of snail tissues and symbiotic corpuscles to bioconcentrate and depurate mercury, arsenic, and uranium. Adult snails cultured in metal-free reconstituted water were exposed for eight weeks (bioaccumulation phase) to water with Hg (2 mu gL(-1)), As (10 mu gL(-1)), and U (30 mu gL(-1)) and then returned to the reconstituted water for other additional eight weeks (depuration phase). Elemental concentrations in digestive gland, kidney, symbiotic corpuscles and particulate excreta were determined by neutron activation analysis. The glandular symbiotic occupancy was measured by morphometric analysis. After exposure, the kidney showed the highest concentration of Hg, while the digestive gland accumulated mainly As and U. The subcellular distribution in symbiotic corpuscles was similar to 71%, similar to 48%, and similar to 11% for U, Hg, and As, respectively. Tissue depuration between weeks 8 and 16 was variable amongst elements. At week 16, the tissue depuration of U was the highest (digestive gland = 92%; kidney = 80%), while it was lower for Hg (digestive gland = 51%; kidney = 53%). At week 16, arsenic showed a differential pattern of tissue depuration (digestive gland = 23%; kidney = 88%). The symbiotic detoxification of the three elements in excreta was fast between weeks 8 and 10 and it was slower after on. At the end of the depuration, each element distributed differentially in digestive gland and symbiotic corpuscles. Our findings show that symbiotic corpuscles, digestive gland and kidney P. canaliculata are sensitive places for biomonitoring of Hg, As and U. (C) 2017 Elsevier Ltd. All rights reserved.
Acena, A ;Lopez, E ; Llerena, M ; PHYSICAL REVIEW D ,2018 ,97 ,-.
We study the existence and stability of isoperimetric surfaces in a family of rotating black holes in new massive gravity. We show that the stability of such surfaces is determined by the sign of the hair parameter. We use the isoperimetric surfaces to find a geometric inequality between the area and the angular momentum of the black hole, conjecturing geometric inequalities for more general black holes.
Shiryaev, AA ;Hinks, JA ; Marks, NA ; Greaves, G ; Valencia, FJ ; Donnelly, SE ; Gonzalez, RI ; Kiwi, M ; Trigub, AL ; Bringa, EM ; Fogg, JL ; Vlasov, II ; SCIENTIFIC REPORTS ,2018 ,8 ,-.
Nanoparticles are ubiquitous in nature and are increasingly important for technology. They are subject to bombardment by ionizing radiation in a diverse range of environments. In particular, nanodiamonds represent a variety of nanoparticles of significant fundamental and applied interest. Here we present a combined experimental and computational study of the behaviour of nanodiamonds under irradiation by xenon ions. Unexpectedly, we observed a pronounced size effect on the radiation resistance of the nanodiamonds: particles larger than 8 nm behave similarly to macroscopic diamond (i.e. characterized by high radiation resistance) whereas smaller particles can be completely destroyed by a single impact from an ion in a defined energy range. This latter observation is explained by extreme heating of the nanodiamonds by the penetrating ion. The obtained results are not limited to nanodiamonds, making them of interest for several fields, putting constraints on processes for the controlled modification of nanodiamonds, on the survival of dust in astrophysical environments, and on the behaviour of actinides released from nuclear waste into the environment.
D'Angelo, JA ;Zodrow, EL ; INTERNATIONAL JOURNAL OF COAL GEOLOGY ,2018 ,189 ,70 -74 .
For the first time, a cutin polymer was obtained from specimens of Johnstonia coriacea (Corystospermales, Corystospermaceae) from the Upper Triassic of Cacheuta, Argentina. These are preserved as fossilized cuticles i.e., naturally macerated compressions under anoxic conditions. Laboratory oxidation reactions were used to obtain the cuticle, which after additional, long-term oxidation yielded the cutin polymer. Cutin, cuticles, and fossilized cuticles, were analyzed by semi-quantitative Fourier transform infrared (FTIR) spectroscopy. Cutin IR spectrum was mainly characterized by intense peaks of aliphatic stretching bands at 3000-2600 cm(-1), ester C=O groups centered at 1730-1715 cm(-1), and aromatic C=C absorption bands at 1645-1640 cm(-1). Values of semi-quantitative, IR-derived ratios of cutin were lower than those of the cuticle. The only exception was the notably higher C=O/C=C ratio found in cutin, which is supportive of the presence of ester C=0 groups. CHal/C=O value (0.8) of J. coriacea compares with those recorded for Iycopenicon esculentum (0.8; extant) and Macroneuropte is sheuchseti (0.9; Pennsylvanian), which indicates a similar cross-linking degree of the monomers characterizing the cutin of both extant and fossil taxa.
Via, MA ;Del Popolo, MG ; Wilke, N ; LANGMUIR ,2018 ,34 ,3102 -3111 .
Cell-penetrating peptides (CPPs) are polycationic sequences of amino acids recognized as some of the most effective vehicles for delivering membrane-impermeable cargos into cells. CPPs can traverse cell membranes by direct translocation, and assessing the role of lipids on the membrane permeation process is important to convene a complete model of the CPP translocation. In this work, we focus on the biophysical basis of peptide-fatty acid interactions, analyzing how the acid-base and electrostatic properties of the lipids determine the CPP adsorption and incorporation into a Langmuir monolayer, focusing thus on the first two stages of the direct translocation mechanism. We sense the binding and insertion of the peptide into the lipid structure by measuring the changes in the surface pressure, the surface potential, and the reflectivity of the interface. We show that, beyond the presence of anionic moieties, negative dipole potentials and carboxylic polar head groups significantly promote the insertion of the peptide into the monolayer. On the basis of our results, we propose the appearance of stable CPP-lipid complexes whose kinetics of formation depends on the length of the lipids' hydrocarbon chains.
Sassi, PL ;Menendez, J ; Cuevas, MF ; JOURNAL OF ZOOLOGY ,2018 ,304 ,210 -216 .
Variation in life-history traits is shaped by intrinsic and extrinsic factors. Climate influences the availability of energy and nutrients in the environment, and thus animals' energy balance, their allocation of resources to reproduction and ultimately, fitness. Temperature is reported as a prevailing influence on animals' investment in reproduction, and diverse hypotheses propose mechanisms by which it occurs. Central and external limits to energy acquisition have been traditionally assumed. Hence, digestive limitations, periods of low food availability or demanding cold conditions would restrict this input. However, under warm conditions endotherms also face the need to dissipate heat from metabolic processes. From this perspective, a high metabolic rate process, such as lactation, would be restricted under increasing ambient temperatures (T-a). Our research addresses the variation in reproductive parameters in Phyllotis xanthopygus, a rodent species broadly distributed in the west highlands and southern parts of South America. Across a pronounced elevation gradient in the central Andes Mountains we found that litter size is comparatively smaller in pregnant females collected at lower elevations. This is congruent with expectations from the heat dissipation limit hypothesis. To disentangle the role of temperature on this pattern, we bred individuals under two thermal treatments. We recorded no changes in the litter size, but pups' body mass was lower at higher T-a during lactation, also in agreement with decreased metabolism. Offspring size and number are relevant to a species' fitness. The evidence suggests that in P.xanthopygus these traits vary geographically and are shaped by T-a in the laboratory. A species that evolved in high altitudes, inhabits cold and temperate areas and is sensitive to T-a increases in the laboratory, appears as an excellent candidate to further explore the ecophysiology-thermal landscape interface, crucial to develop accurate predictive models of biodiversity dynamics.
Galassi, VV ;Salinas, SR ; Montich, GG ; EUROPEAN BIOPHYSICS JOURNAL WITH BIOPHYSICS LETTERS ,2018 ,47 ,165 -177 .
We studied the conformational changes of the fatty acid-binding protein ReP1-NCXSQ in the interface of anionic lipid membranes. ReP1-NCXSQ is an acidic protein that regulates the activity of the Na+/Ca2+ exchanger in squid axon. The structure is a flattened barrel composed of two orthogonal beta-sheets delimiting an inner cavity and a domain of two alpha-helix segments arranged as a hairpin. FTIR and CD spectroscopy showed that the interactions with several anionic lipids in the form of small unilamellar vesicles (SUVs) induced an increase in the proportion of helix secondary structure. Lower amount or no increase in alpha-helix was observed upon the interaction with anionic lipids in the form of large unilamellar vesicles (LUVs). The exception was 1,2-dimyristoyl-sn-glycero-3-phosphoglycerol (DMPG) that was equally efficien to to induce the conformational change both in SUVs and in LUVs. In solution, the infrared spectra of ReP1-NCXSQ at temperatures above the unfolding displayed a band at 1617 cm(-1) characteristic of aggregated strands. This band was not observed when the protein interacted with DMPG, indicating inhibition of aggregation in the interface. Similarly to the observed in L-BABP, another member of the fatty acid binding proteins, a conformational change in ReP1-NCXSQ was coupled to the gel to liquid-crystalline lipid phase transition.
Alhafez, IA ;Ruestes, CJ ; Urbassek, HM ; TRIBOLOGY LETTERS ,2018 ,66 ,-.
Nanoscratching of ductile materials creates plastic zones surrounding the scratch groove. We approximate the geometry of these zones by a semicylinder with its axis oriented along the scratch direction. The radius and the length of the cylinder, as well as the length of the dislocations in the network created quantify the plasticity generated. Using molecular dynamics simulations, we characterize the plastic zones in six metals with fcc, bcc, and hcp crystal structures. We find that the plastic zone sizes after scratch are comparable to those after indent. Due to dislocation reactions, the dislocation networks simplify, reducing the total length of dislocations. As a consequence, the average dislocation density in the plastic zone stays roughly constant. Individually, we find exceptions from this simple picture. Fcc metals show strong plastic activity, which even increases during scratch. The hcp metals on the other side show the least plastic activity. Here the plasticity may be strongly reduced during scratch and particularly during tip withdrawal.
David, LDO ;Riga, BJG ; Kellner, AWA ; CRETACEOUS RESEARCH ,2018 ,83 ,40 -46 .
A giant humerus (450 mm total length) belonging to one of the largest pterosaur recorded in South America is described. The specimen (UNCUYO-LD 350) was discovered in the Upper Cretaceous (upper Coniacian - lower Santonian) Plottier Formation of the Mendoza Province, northern Neuquen Basin, Argentina. It was found associated with a smaller pterosaur specimen represented by around thirty postcranial bones. The specimen is assigned to Tapejaroidea and show characters of both Tapejaridae and Azhdarchidae. Based on comparisions with other Azdharchidae species, a wingspan of 9.1 m is estimated for UNCUYO-LD 350, showing that giant pterosaurs were present in South America during the Upper Cretaceous. (C) 2017 Elsevier Ltd. All rights reserved.
Canizo, BV ;Escudero, LB ; Perez, MB ; Pellerano, RG ; Wuilloud, RG ; FOOD CHEMISTRY ,2018 ,242 ,272 -278 .
The feasibility of the application of chemometric techniques associated with multi-element analysis for the classification of grape seeds according to their provenance vineyard soil was investigated. Grape seed samples from different localities of Mendoza province (Argentina) were evaluated. Inductively coupled plasma mass spectrometry (ICP-MS) was used for the determination of twenty-nine elements (Ag, As, Ce, Co, Cs, Cu, Eu, Fe, Ga, Gd, La, Lu, Mn, Mo, Nb, Nd, Ni, Pr, Rb, Sm, Te, Ti, Tl, Tm, U, V, Y, Zn and Zr). Once the analytical data were collected, supervised pattern recognition techniques such as linear discriminant analysis (LDA), partial least square discriminant analysis (PLS-DA), k-nearest neighbors (k-NN), support vector machine (SVM) and Random Forest (RF) were applied to construct classification/discrimination rules. The results indicated that nonlinear methods, RF and SVM, perform best with up to 98% and 93% accuracy rate, respectively, and therefore are excellent tools for classification of grapes.
De Francesco, AM ;Barca, D ; Bocci, M ; Cortegoso, V ; Barberena, R ; Yebra, L ; Duran, V ; QUATERNARY INTERNATIONAL ,2018 ,468 ,134 -140 .
By means of inductively Coupled Plasma Mass Spectrometry associated with Laser Ablation (LA-ICP-MS) we analyzed several obsidian artifacts from the Natural Protected Area Laguna del Diamante (Mendoza, Argentina) and upper Maipo valley (Chile). This analytical method, almost non-destructive, is a powerful tool for the determination of trace elements and is very useful in characterizing and determining the provenance of obsidian fragments of archeological interest, although care must be taken to avoid or account for heterogeneities within obsidian such as microcrysts.
Via, MA ;Klug, J ; Wilke, N ; Mayorga, LS ; Del Popolo, MG ; PHYSICAL CHEMISTRY CHEMICAL PHYSICS ,2018 ,20 ,5180 -5189 .
Cell-penetrating peptides (CPP) are short sequences of cationic amino-acids that show a surprising ability to traverse lipid bilayers. CPP are considered to be some of the most effective vectors to introduce membrane-impermeable cargos into cells, but the molecular basis of the membrane translocation mechanisms and its dependence on relevant membrane physicochemical properties have yet to be fully determined. In this paper we resort to Molecular Dynamics simulations and experiments to investigate how the electrostatic potential across the lipid/water interface affects the insertion of hydrophilic and amphipathic CPP into two-dimensional lipid structures. Simulations are used to quantify the effect of the transmembrane potential on the free-energy profile associated with the transfer of the CPP across a neutral lipid bilayer. It is found that the electrostatic bias has a relatively small effect on the binding of the peptides to the membrane surface, but that it significantly lowers the permeation barrier. A charge compensation mechanism, arising from the segregation of counter-ions while the peptide traverses the membrane, determines the shape and symmetry of the free-energy curves and underlines relevant mechanistic considerations. Langmuir monolayer experiments performed with a variety of amphiphiles model the incorporation of the CPP into the external membrane leaflet. It is shown that the dipole potential of the monolayer controls the extent of penetration of the CPP into the lipid aggregate, to a greater degree than its surface charge.
Drack, JME ;Vazquez, DP ; ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY ,2018 ,148 ,571 -577 .
Cement dust from cement plants around the world has multiple negative effects on organisms and their environment. Cement's effects come from its strongly alkaline nature and high content of heavy metals. Previous studies on plants have documented that cement dust deposition can influence plant vegetative growth, the lipid and ionic composition of tissues, and foliar temperature. Here we evaluate the effects of cement dust coming from a plant in westem Argentina on the morphology of the cactus Tephrocactus aoracanthus. In sites located at 0.15 km, 2 km and 6 km from the cement plant, we recorded five morphological attributes of the cactus: length and number of spines, cladode (stem) diameter, and fresh and dry weight. We also transplanted plants in situ to evaluate the effect of distance from the cement plant. In addition, we set an experiment spreading cement dust weekly on the aerial and ground parts of the cactus. Results of our field observational and experimental studies indicate that cement dust deposition on aerial parts of the plant leads to increased spine length, number of spines, and wet and dry weights of cladodes.
Maniero, MA ;Guerrero-Gimenez, ME ; Fanelli, MA ; Wuilloud, RG ; BIOMETALS ,2018 ,31 ,69 -80 .
The viability, cellular uptake and subcellular distribution of heavy metal Hg, were determined in human mammary cell lines (MCF-7, MDA-MB-231 and MCF-10A). It was observed that Hg had the capacity of being excluded from the cells with a different type of possible transporters. MCF-7 cells showed the lowest viability, while the other two cell lines were much more resistant to Hg treatments. The intracellular concentration of Hg was higher at lower exposure times in MCF-10A cells and MCF-7 cells; but as the time was increased only MDA-MB-231 showed the capacity to continue introducing the metal. In MCF-7 and MCF-10A cells the subcellular distribution of Hg was higher in cytosolic fraction than nucleus and membrane, but MDA-MB-231 showed membrane and nucleus fraction as the enriched one. The analysis of RNA-seq about the genes or family of genes that encode proteins which are related to cytotoxicity of Hg evidenced that MCF-10A cells and MCF-7 cells could have an active transport to efflux the metal. On the contrary, in MDA-MB-231 no genes that could encode active transporters have been found.
Rosandi, Y ;Grossi, J ; Bringa, EM ; Urbassek, HM ; JOURNAL OF APPLIED PHYSICS ,2018 ,123 ,-.
The incidence of energetic laser pulses on a metal foam may lead to foam ablation. The processes occurring in the foam may differ strongly from those in a bulk metal: The absorption of laser light, energy transfer to the atomic system, heat conduction, and finally, the atomistic processes-such as melting or evaporation-may be different. In addition, novel phenomena take place, such as a reorganization of the ligament network in the foam. We study all these processes in an Au foam of average porosity 79% and an average ligament diameter of 2.5 nm, using molecular dynamics simulation. The coupling of the electronic system to the atomic system is modeled by using the electron-phonon coupling, g, and the electronic heat diffusivity, kappa(e), as model parameters, since their actual values for foams are unknown. We show that the foam coarsens under laser irradiation. While kappa(e) governs the homogeneity of the processes, g mainly determines their time scale. The final porosity reached is independent of the value of g. Published by AIP Publishing.
Duran, V ;Novellino, P ; Menendez, L ; Gasco, A ; Marsh, E ; Barberena, R ; Frigole, C ; RELACIONES ,2018 ,43 ,55 -86 .
We present an interdisciplinary research of the human remains and grave goods recovered from the Barrio Ramos I burial, localized in the Uspallata Valley (Mendoza, Argentina). We reassess the traditional assignment of the site to the late 'Agroalfarero' period. Based on a bayesian analysis of the available radiocarbon dates for the site, and by integrating regional contexts with similar chronology, we suggest that Barrio Ramos I falls within the period of Inca domination. The analysis of lithic, ceramic, and bone artifacts recovered from the burial support this inference. By means of isotopic and bioarchaeological studies of the remains, we offer valuable insights on the lifeway and geographic origin of some of the individuals found at the site.
Gimenez, VMM ;Camargo, AB ; Kassuha, D ; Manucha, W ; CURRENT PHARMACEUTICAL DESIGN ,2018 ,24 ,4681 -4684 .
Atherosclerosis provokes a continuous worsening of affected vessels causing a blood flow diminution with several complications and with clinical manifestations that generally appear in advanced phases of the illness. Hence, the conventional therapies are not enough because the atherosclerotic injuries are often irrevocable. For this reason, emerges the necessity to implement smart ways of drug supply and develop new therapeutic targets that decrease the advance atherosclerotic lesion. It results due to particular interest to use new tools for prevention, diagnosis, and treatment of this cardiovascular disease, thus concentrating our attention to accomplish better management on the immune system. Finally, this mini-review highlights the most recent knowledge about nanotechnology as a robust, novel and promissory therapeutic option applied to atherosclerotic pathology, nevertheless, we also alert for possible issues associated with their use.
Zarco, A ;Benitez, VV ; Fasola, L ; Funes, G ; Guichon, ML ; HYSTRIX-ITALIAN JOURNAL OF MAMMALOGY ,2018 ,29 ,223 -228 .
Knowledge of food habits of invasive species is necessary to predict invasion success and potential interactions in the invaded community. The Asiatic red-bellied squirrel Callosciurus erythraeus has been introduced in Asia, Europe and South America. We studied feeding habits of red-bellied squirrels in Argentina in two sites 600 km apart where wild populations have become established. We used both faecal microhistological analysis and behavioural records to describe diet composition and feeding habits. We also analysed diet selection and the potential role of the squirrels as seed disperser. Squirrels consumed items from 35 species of exotic trees and shrubs and one native tree species; fruits and seeds represented the bulk of the diet in all seasons (faeces analysis: >44%; behavioural observations: >38%). Squirrels also consumed epiphytic and climbing plants, ferns, invertebrates, fungi, lichens, mosses and bird eggs. Diet composition varied throughout the year according to food availability. We did not find evidence of endozoochoric dispersal but we observed squirrels carrying and dropping nuts and acorns during transport. The consumption of a wide range of food items and species, the ability to modify the diet according to food availability, and the capacity to hoard food indicate that feeding habits of red-bellied squirrels favour their invasive potential.
Frontini-Lopez, YR ;Gojanovich, AD ; Masone, D ; Bustos, DM ; Uhart, M ; BIOCELL ,2018 ,42 ,67 -77 .
In the last years, much work has shown that the most effective repair system of the body is represented by stem cells, which are defined as undifferentiated precursors that own unlimited or prolonged self-renewal ability, which also have the potential to transform themselves into various cell types through differentiation. All tissues that form the body contain many different types of somatic cells, along with stem cells that are called 'mesenchymal stem (or stromal) cells' (MSC). In certain circumstances, some of these MSC migrate to injured tissues to replace dead cells or to undergo differentiation to repair it. The discovery of MSC has been an important step in regenerative medicine because of their high versatility. Moreover, the finding of a method to isolate MSC from adipose tissue, so called 'adipose-derived mesenchymal stem cells' (ASC), which share similar differentiation capabilities and isolation yield that is greater than other MSC, and less bioethical concerns compared to embryonic stem cells, have created self-praised publicity to procure almost any treatment with them. Here, we review the current techniques for isolation, culture and differentiation of human ASC (hASC), and describe them in detail. We also compile some advantages of the hASC over other stem cells, and provide some concepts that could help finding strategies to promote their therapeutic efficiency.
Laurito, S ;Cueto, JA ; Perez, J ; Roque, M ; BIOCELL ,2018 ,42 ,87 -91 .
Spinal muscular atrophy (SMA) is caused by dysfunction of the alpha motor neurons of the spinal cord. It is an autosomal recessive disease associated to the SMN1 gene, located in the subtelomeric region of 5q13. A paralog SMN2 gene is located at the centromeric region of the same chromosome, which apparently originated by an ancestral inverted duplication occurring only in humans. The exon sequence differs in two nucleotides in exon 7 and exon 8, which leads to an SMN2 transcript that lacks exon 7 and results in a truncated protein. Part (10%) of the SMN2 transcripts avoids the splicing of exon 7 but most of the copies are dysfunctional. In a disease scenario, the more SMN2 copies the higher possibility to restore at least partly the effects of SMN1 deficiency. Some therapeutic approaches are being developed to increase the expression of SMN2. To determine the number of SMN1 and SMN2 copies, the methodology must distinguish accurately between both genes. In this work, we present the results obtained using multiplex ligation-dependent probe amplification (MLPA) in 60 SMA suspected patients/carriers derived from different regions of Argentina. In 32 of these DNA samples we found alterations in SMN1. Among these, 16 presented a heterozygous deletion (carrier status) and 14 an homozygous deletion (patient status) in exon 7 and 8 of SMN1. In one case, exon 7 was found homozygously deleted but exon 8 presented a single copy, and in another case, exon 7 was found heterozygously deleted while exon 8 was normal. Almost half of the patients (7/15) presented a normal diploid number of SMN2 while the other half (8/15) presented an increased number. In this work we showed how a probe-based methodology such as MLPA was able to distinguish between the paralog genes and determine the amount of copies in DNA samples from suspected patients/carriers of SMA.
Escudero, LB ;Agostini, E ; Dotto, GL ; CHEMICAL ENGINEERING COMMUNICATIONS ,2018 ,205 ,122 -133 .
Tobacco hairy roots (THR) were used to evaluate its potential for the biosorption and removal of malachite green (MG) from aqueous solutions. A 3(2) full factorial design was applied to study the effects of pH and THR concentration on the biosorption capacity. Under the optimal conditions (pH of 7.0 and THR concentration of 1gL(-1)), dye removal efficiency was around 92%. Experimental data obtained from kinetic studies demonstrated good concordance with the pseudo-second-order model. Equilibrium studies were developed and the data were evaluated by Langmuir, Freundlich, and Sips models, being the Sips model the most adequate (maximum biosorption capacity of 277.2mgg(-1)). Thermodynamically, the biosorption of MG on THR proved to be endothermic, spontaneous, and favorable. Desorption was feasible under acidic conditions and the biosorbent could be reused three times. THR was tested in simulated effluent and the removal percentage was 87%, demonstrating that this material is a promising biosorbent which can be used to treat colored wastewaters.
Escudero, LB ;Vanni, G ; Duarte, FA ; Segger, T ; Dotto, GL ; CHEMICAL ENGINEERING COMMUNICATIONS ,2018 ,205 ,325 -337 .
The potential of wine industry wastes (grape peel, seed, and stem) as alternative biosorbents to remove Ag from aqueous media was investigated in this work. Wine industry wastes were washed, lyophilized and pulverized to obtain the biosorbents. The powdered biosorbents were characterized in detail and several batch experiments were performed to found the most suitable conditions for Ag biosorption. Kinetic, equilibrium, and thermodynamic studies were also performed. The interactions Ag-biosorbent were elucidated by analyses before and after the biosorption. For all wastes, the maximum removal percentages were found using a biosorbent dosage of 3.0 g L-1 at pH of 7.0. The kinetic data were well represented by the pseudo-first-order model. The equilibrium was satisfactorily represented by the Sips model. The maximum biosorption capacities, found at 298K, were: 41.7, 61.4, and 46.4 mg g(-1) for grape peel, seed, and stem, respectively. Thermodynamically, the biosorption was a spontaneous, favorable, exothermic, and enthalpy-controlled process. The magnitude of H-0 indicated a physical sorption. These results showed that the wine industry wastes can be considered alternative efficient, low-cost, and eco-friendly biosorbents to remove Ag from aqueous media.
Berberian, MV ;Pocognoni, CA ; Mayorga, LS ; INTERNATIONAL JOURNAL OF NANOMEDICINE ,2018 ,13 ,8075 -8086 .
Background: Nanoparticles' intracellular fate requires proper internalization. Most cells make use of a battery of internalization pathways, but some are practically sealed, as they lack the biochemical machinery for cellular intake. Non-endocytic cells, such as mammals' spermatozoa, challenge standard drug-delivery strategies.
Laurito, S ;Roque, M ; MEDICINA-BUENOS AIRES ,2018 ,78 ,1 -5 .
Human chromosome 15q11-q13 region is prone to suffer genetic alterations. Some genes of this region have a differential monoallelic imprinting-regulated expression pattern. Defects in imprinting regulation (IE), uniparental disomy (UPD) or copy number variation (CNV) due to chromosomal breakpoints (BP) in 15q11-q13 region, are associated with several diseases. The most frequent are Prader-Willi syndrome, Angelman syndrome and 15q11-q13 microduplication syndrome. In this work, we analyzed DNA samples from 181 patients with phenotypes which were compatible with the above-mentioned diseases, using Methyl specific-multiplex ligation-dependent probe amplification (MS-MLPA). We show that, of the 181 samples, 39 presented alterations detectable by MS-MLPA. Of those alterations, 61.5% (24/39) were deletions, 5.1% (2/39) duplications and 33.3% (13/39) UPD/IE. The CNV cases were 4 times more frequent than UPD/IE (OR=4; IC 95%: 1.56-10.25), consistent with the literature. Among the CNVs, two atypical cases allow to postulate new possible BP sites that have not been reported previously in the literature.
Gari, Y ;Monge, DA ; Mateos, C ; Garino, CG ; HIGH PERFORMANCE COMPUTING ,2018 ,796 ,353 -369 .
Spot instances are extensively used to take advantage of large-scale Cloud infrastructures at lower prices than traditional on-demand instances. Autoscaling scientific workflows in the Cloud considering both spot and on-demand instances presents a major challenge as the autoscalers have to determine the proper amount and type of virtual machine instances to acquire, dynamically adjusting the number of instances under each pricing model (spots or on-demand) depending on the workflow needs. Under budget constraints, this adjustment is performed by an assignment policy that determines the suitable proportion of the available budget intended for each model. We propose an approach to derive an adaptive budget assignment policy able to reassign the budget at any point in the workflow execution. Given the inherent variability of the resources in a Cloud, we formalize the described problem as a Markov Decision Process and derive adaptive policies based on other baseline policies. Experiments demonstrate that our policies outperform all the baseline policies in terms of makespan and most of them in terms of cost. These promising results encourage the future study of new strategies aiming to find optimal budget policies applied to the execution of workflows on the Cloud.
Castro, SC ;ARQUEOLOGIA ,2018 ,24 ,99 -121 .
The ARQ-18 rock shelter, located in the northwestern cordillera of the San Juan Province of Argentina, has a long occupational sequence (ca. 8,000 years BP). A middle Holocene hiatus of 1,600 years separates high residential mobility hunter-gatherer occupation from transhumant herder occupation. This article evaluates changes in the organization of lithic technology linked to transformations in subsistence and mobility. Our analysis addresses the origin of resources, artifact density, reduction sequences, artifact variability, and technical classes. The data demonstrates that the transition to a diversified economy resulted in longer stays, a greater diversity of tasks, the use of mostly expedient and opportunistic strategies, and a decrease in time invested in the making of lithic implements. Curation strategies are linked to a continuity of hunting as an economic activity.
Erquiaga, MJ ;Garcia, S ; Garino, CG ; COMPUTER SCIENCE (CACIC 2017) ,2018 ,790 ,272 -281 .
During the last couple of years there has been an important surge on the use of HTTPs by malware. The reason for this increase is not completely understood yet, but it is hypothesized that it was forced by organizations only allowing web traffic to the Internet. Using HTTPs makes malware behavior similar to normal connections. Therefore, there has been a growing interest in understanding the usage of HTTPs by malware. This paper describes our research to obtain large quantities of real malware traffic using HTTPs, our use of man-in-the-middle HTTPs interceptor proxies to open and study the content, and our analysis of how the behavior of the malware changes after being intercepted. The research goal is to understand how malware uses HTTPs and the impact of intercepting its traffic. We conclude that the use of an interceptor proxy forces the malware to change its behavior and therefore should be carefully considered before being implemented.
Llambias, PE ;Garrido, PS ; Jefferies, MM ; Fernandez, GJ ; JOURNAL OF ORNITHOLOGY ,2018 ,159 ,221 -231 .
The study of geographic variation of social mating systems can shed new light on our understanding of how ecological variables shape extant mating associations. We report data on the social mating system, parental care and life history traits of a temperate population of southern Sedge Wrens (Cistothorus platensis platensis) in South America. We compared our results with published records of two temperate populations of northern Sedge Wren (Cistothorus platensis stellaris) in North America. The southern temperate population had a lower social polygyny rate, greater male contribution to feeding nestlings and smaller clutch sizes than northern temperate populations. A similar pattern of low rates of social polygyny and smaller clutch sizes in the south versus moderate rates of social polygyny and bigger clutch sizes in the north has been reported for the House Wren (Troglodytes aedon). This suggests that different selective forces may be operating in northern and southern wren populations. Future work in additional study populations is essential to establishing the generality of our results.
Chacoff, NP ;Resasco, J ; Vazquez, DP ; ECOLOGY ,2018 ,99 ,21 -28 .
Ecological interactions are highly dynamic in time and space. Previous studies of plant-animal mutualistic networks have shown that the occurrence of interactions varies substantially across years. We analyzed interannual variation of a quantitative mutualistic network, in which links are weighted by interaction frequency. The network was sampled over six consecutive years, representing one of the longest time series for a community-wide mutualistic network. We estimated the interannual similarity in interactions and assessed the determinants of their persistence. The occurrence of interactions varied greatly among years, with most interactions seen in only one year (64%) and few (20%) in more than two years. This variation was associated with the frequency and position of interactions relative to the network core, so that the network consisted of a persistent core of frequent interactions and many peripheral, infrequent interactions. Null model analyses suggest that species abundances play a substantial role in generating these patterns. Our study represents an important step in the study of ecological networks, furthering our mechanistic understanding of the ecological processes driving the temporal persistence of interactions.
Gomez, LC ;Sottile, ML ; Guerrero-Gimenez, ME ; Zoppino, FCM ; Redondo, AL ; Gago, FE ; Orozco, JI ; Tello, OM ; Roque, M ; Nadin, SB ; Marzese, DM ; Vargas-Roig, LM ; JOURNAL OF CLINICAL PATHOLOGY ,2018 ,71 ,52 -58 .
Aim Accumulated evidence suggests that aberrant methylation of the TP73 gene and increased levels of Delta Np73 in primary tumours correlate with poor prognosis. However, little is known regarding the transcriptional and functional regulation of the TP73 gene in breast cancer. The aim of the present study was to determine the expression of the Delta Np73 isoform, its relationship with DNA methylation of TP73 and their clinical prognostic significance in breast cancer patients.
Koenig, TK ;Volkamer, R ; Baidar, S ; Dix, B ; Wang, SY ; Anderson, DC ; Salawitch, RJ ; Wales, PA ; Cuevas, CA ; Fernandez, RP ; Saiz-Lopez, A ; Evans, MJ ; Sherwen, T ; Jacob, DJ ; Schmidt, J ; Kinnison, D ; Lamarque, JF ; Apel, EC ; Bresch, JC ; Campos, T ; Flocke, FM ; Hall, SR ; Honomichl, SB ; Hornbrook, R ; Jensen, JB ; Lueb, R ; Montzka, DD ; Pan, LL ; Reeves, JM ; Schauffler, SM ; Ullmann, K ; Weinheimer, AJ ; Atlas, EL ; Donets, V ; Navarro, MA ; Riemer, D ; Blake, NJ ; Chen, DX ; Huey, LG ; Tanner, DJ ; Hanisco, TF ; Wolfe, GM ; ATMOSPHERIC CHEMISTRY AND PHYSICS ,2017 ,17 ,15245 -15270 .
We report measurements of bromine monoxide (BrO) and use an observationally constrained chemical box model to infer total gas-phase inorganic bromine (Br-y) over the tropical western Pacific Ocean (tWPO) during the CONTRAST field campaign (January-February 2014). The observed BrO and inferred Bry profiles peak in the marine boundary layer (MBL), suggesting the need for a bromine source from sea-salt aerosol (SSA), in addition to organic bromine (CBry). Both profiles are found to be C-shaped with local maxima in the upper free troposphere (FT). The median tropospheric BrO vertical column density (VCD) was measured as 1 : 6 X 10(13) molec Cm-2, compared to model predictions of 0 : 9 X 10(13) molec cm(-2) in GEOS-Chem (CBry but no SSA source), 0 : 4 X 10(13) molec cm(-2) in CAM-Chem (CBry and SSA), and 2 : 1 X 10(13) molec cm(-2) in GEOS-Chem (CBry and SSA). Neither global model fully captures the C-shape of the Br-y profile. A local Br-y maximum of 3.6 ppt (2.9-4.4 ppt; 95% confidence interval, CI) is inferred between 9.5 and 13.5 km in air masses influenced by recent convective outflow. Unlike BrO, which increases from the convective tropical tropopause layer (TTL) to the aged TTL, gas-phase Br-y decreases from the convective TTL to the aged TTL. Analysis of gas-phase Br-y against multiple tracers (CFC-11, H2O = O-3 ratio, and potential temperature) reveals a Br-y minimum of 2.7 ppt (2.3-3.1 ppt; 95% CI) in the aged TTL, which agrees closely with a stratospheric injection of 2 : 6 X 0 : 6 ppt of inorganic Br-y (estimated from CFC-11 correlations), and is remarkably insensitive to assumptions about heterogeneous chemistry. Br-y increases to 6.3 ppt (5.6-7.0 ppt; 95% CI) in the stratospheric "middle-world" and 6.9 ppt (6.5-7.3 ppt; 95% CI) in the stratospheric "overworld". The local Br-y minimum in the aged TTL is qualitatively (but not quantitatively) captured by CAM-Chem, and suggests a more complex partitioning of gas-phase and aerosol Br-y species than previously recognized. Our data provide corroborating evidence that inorganic bromine sources (e.g., SSA-derived gas-phase Br-y) are needed to explain the gas-phase Br-y budget in the upper free troposphere and TTL. They are also consistent with observations of significant bromide in Upper Troposphere-Lower Stratosphere aerosols. The total Br-y budget in the TTL is currently not closed, because of the lack of concurrent quantitative measurements of gas-phase Br-y species (i.e., BrO, HOBr, HBr, etc.) and aerosol bromide. Such simultaneous measurements are needed to (1) quantify SSA-derived Br-y in the upper FT, (2) test Br-y partitioning, and possibly explain the gas-phase Bry Br-y minimum in the aged TTL, (3) constrain heterogeneous reaction rates of bromine, and (4) account for all of the sources of Br-y to the lower stratosphere.
Klug, J ;Torresan, MF ; Lurgo, F ; Borioli, G ; Lacconi, GI ; JOURNAL OF COLLOID AND INTERFACE SCIENCE ,2017 ,508 ,532 -541 .
We developed a highly sensitive silicon platform, suitable to assess the molecular organization of protein samples. Prototype platforms were obtained using different electrochemical protocols for the electrode position of Ag-nanoparticles onto the hydrogenated silicon surface. A platform with high Surface Enhanced Raman Scattering efficiency was selected based on the surface coverage and the number density of particles size distribution. The performance of the platform was determined by studying the interaction of Myristoylated Alanine-Rich C Kinase Substrate (MARCKS) protein with the substrate according to its molecular organization. The chemical and structural characteristics of MARCKS molecules were examined under two configurations: i) a disordered distribution given by a MARCKS solution drop deposited onto the platform and, ii) a compact monolayer transferred to the platform by the Langmuir-Blodgett method. Raman spectra show vibrational bands of Phenylalanine and Lysine residues specific for the protein effector domain, and evidence the presence of alpha helix structure in both configurations. Moreover, we distinguished the supramolecular order between the compact monolayer and random molecular distribution. The platforms containing Ag-nanoparticles are suitable for studies of protein structure and interactions, advancing a methodological strategy for our long term goal, which is to explore the interaction of proteins with model membranes. (C) 2017 Elsevier Inc. All rights reserved.
Llaver, M ;Coronado, EA ; Wuilloud, RG ; SPECTROCHIMICA ACTA PART B-ATOMIC SPECTROSCOPY ,2017 ,138 ,23 -30 .
A highly sensitive and efficient dispersive micro-solid phase extraction (D-mu-SPE) method was developed for inorganic Se speciation analysis. A novel ionic liquid (IL)-nanomaterial hybrid consisting of 1-dodecyl-3-methylimidazolium bromide-functionalized nanosilica was used for the efficient retention of Se(IV) complexed with ammonium pyrrolidine dithiocarbamate, followed by elution with an ethyl acetate/Triton X-114 mixture and determination by electrothermal atomic absorption spectroscopy. The Se(VI) species was selectively determined by difference between total inorganic Se and Se(IV) after pre-reduction. The IL-nanomaterial hybrid was characterized by Fourier transform infrared spectroscopy and transmission electronic microscopy. Likewise, Se(IV) sorption capacity of the retention material and maximum amount of IL loaded on its surface were determined. Several factors concerning the functionalization, extraction and elution steps were optimized, yielding a 100% extraction efficiency for Se(IV) under optimal conditions. A limit of detection of 1.1 ng L-1, a relative standard deviation of 5.7% and a 110-fold enhancement factor were obtained. The D-mu-SPE method was successfully applied to several water samples from different origins and compositions, including rain, tap, underground, river and sea. (C) 2017 Elsevier B.V. All rights reserved.
Martinis, EM ;Grijalba, AC ; Perez, MB ; Llaver, M ; Wuilloud, RG ; TRAC-TRENDS IN ANALYTICAL CHEMISTRY ,2017 ,97 ,333 -344 .
Nanomaterials and ionic liquids (ILs) have very attractive properties for improved analytical preconcentration methods. Thus, ILs have been used as excellent tools to functionalize nanomaterials, giving them specific chemical properties for higher selectivity, extraction efficiency and extended re-utilization in pre-concentration. Moreover, incorporation of IL-nanomaterial hybrids in miniaturized solid phase and liquid phase microextraction procedures is being increasingly exploited to obtain high analytical recoveries while developing environmentally friendly analytical methods. In this review, the design and application of innovative and efficient analytical methods for sensitive and selective determination of inorganic and organic analytes is described. The synthesis of some IL-nanomaterial hybrids is presented along with a revision of the most important synergistic physicochemical properties useful for the extraction of analytes. Finally, practical considerations concerning the application of IL-nanomaterial hybrids for the development of modern analytical separation and preconcentration techniques are fully discussed in this work. (C) 2017 Elsevier B.V. All rights reserved.
Novitskaya, E ;Ruestes, CJ ; Porter, MM ; Lubarda, VA ; Meyers, MA ; McKittrick, J ; JOURNAL OF THE MECHANICAL BEHAVIOR OF BIOMEDICAL MATERIALS ,2017 ,76 ,85 -96 .
Almost all species of modern birds are capable of flight; the mechanical competency of their wings and the rigidity of their skeletal system evolved to enable this outstanding feat. One of the most interesting examples of structural adaptation in birds is the internal structure of their wing bones. In flying birds, bones need to be sufficiently strong and stiff to withstand forces during takeoff, flight, and landing, with a minimum of weight. The cross-sectional morphology and presence of reinforcing structures (struts and ridges) found within bird wing bones vary from species to species, depending on how the wings are utilized. It is shown that both morphology and internal features increases the resistance to flexure and torsion with a minimum weight penalty. Prototypes of reinforcing struts fabricated by 3D printing were tested in diametral compression and torsion to validate the concept. In compression, the ovalization decreased through the insertion of struts, while they had no effect on torsional resistance. An elastic model of a circular ring reinforced by horizontal and vertical struts is developed to explain the compressive stiffening response of the ring caused by differently oriented struts.
Mescua, JF ;Porras, H ; Duran, P ; Giambiagi, L ; de Moor, M ; Cascante, M ; Salazar, E ; Protti, M ; Poblete, F ; TECTONICS ,2017 ,36 ,2936 -2949 .
Contractional deformation in Costa Rica is usually attributed to the subduction of the aseismic Cocos Ridge. In this work, we review the evidences for contraction in the middle to late Miocene, prior to the arrival of the Cocos Ridge at the Middle America Trench. We find that the Miocene phase of contractional deformation is found in all of Costa Rica, probably extending to Nicaragua as well. The widespread distribution of this event requires a regional or plate geodynamic trigger. We analyze the possible mechanisms that could produce the onset of contractional deformation, using the better known case of subduction orogeny, the Andes, as an analog. We propose that a change in the direction of the Cocos plate since similar to 19 Ma led to a change from oblique to orthogonal convergence, producing contractional deformation of the upper plate.
Escudero, LB ;Smichowski, PN ; Dotto, GL ; WATER SCIENCE AND TECHNOLOGY ,2017 ,76 ,3379 -3391 .
In the present work, Iridaea cordata (IC), a red marine macroalgae, was used as an efficient biosorbent for the removal of crystal violet (CV) and methylene blue (MB) dyes from aqueous solutions. The effects of pH (5, 7, and 9) and IC concentration (1, 3, and 5 g L-1) on the biosorption were studied through a 32 full factorial design. Under the optimal conditions (pH: 7, biosorbent concentration: 1 g L-1), biosorption kinetic studies were developed and the obtained experimental data were evaluated by pseudo-first order and pseudo-second order models. The results showed that the pseudo-second order model was in agreement with the experimental kinetic data for both dyes. Equilibrium studies were also carried out, and results exhibited good concordance with the Brunauer-Emmett-Teller isotherm. The biosorption capacities were 36.5 and 45.0 mg g(-1) for CV and MB dyes, respectively. The dye removal percentages were around 75% for CV and 90% for MB. Thermodynamically, the biosorption process proved to be exothermic, spontaneous, and favorable. These results showed that IC biomass is a promising biosorbent for removal of CV and MB dyes from aqueous solutions.
Bertoldi, DS ;Millan, EN ; Guillermet, AF ; JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS ,2017 ,111 ,286 -293 .
The paper presents a thermodynamic study of the melting transition in Au nano-clusters with a number of atoms (N) in the range 10(3) < N < 10(6) using a Molecular Dynamics (MD) technique. This range of sizes allows an analysis of the relations between the properties of the clusters and macroscopic Au. Four steps in the progress of the transition occurring upon heating are identified on thermodynamic and structural basis, and the corresponding temperature ranges are determined. In particular, the step where most of the transition takes place (the "melting step") is identified and described in terms of the change in the relative amount of two kinds of atoms, viz., those forming solid phase-like (SPL) aggregates and those in the liquid phase-like (LPL) aggregates. The energy and entropy change involved in the "melting step" are established as a function of N. These properties are used to evaluate the temperature T-0 at which the SPL and the LPL have equal values of the Helmholtz energy. Furthermore, the possibility of describing the thermodynamics of the "melting step" by means of a formalism involving an isomerization-type reaction between the atoms in the SPL and the LPL is explored. To this aim, an equilibrium constant (K-eq) involving the concentration of such types of atoms is introduced. Finally, it is shown that a thermodynamic, van't Hoff analysis of the size-dependence of k(eq) yields values of the T-0 temperature which are in very good agreement with those obtained from the energy and entropy values.
Aguilera, AC ;Boschin, V ; Robina, I ; Elias-Rodriguez, P ; Sosa, MA ; THERIOGENOLOGY ,2017 ,104 ,134 -141 .
The mammalian epididymis provides an appropriate environment for sperm maturation. During the epididymal transit, spermatozoa undergo biochemical and morphological changes that lead to the acquisition of the fertilizing capacity. In this study we analysed the fucosylation status of membrane glycoproteins in the spermatozoa obtained from different regions of the bull epididymis. High amounts of fucose were detected on caput spermatozoa (R.F.I. = 1010 +/- 20.35), mostly located in the post-acrosome zone. A significant decrease in the fucose levels was detected toward the cauda (R.F.I. = 540.5 +/- 49.93) (P < 0.05). This decrease was in line with the increased activity of alpha-L-fucosidase in the cauda fluid. In sperm from the cauda, the defucosylation occurred in some proteins, whereas others showed higher fucosylation rates. A significant decrease of fucose in the gametes was observed upon incubation of crude cauda fluid with caput spermatozoa (from R.F.I. = 1.45 +/- 0.08 to 1.06 +/- 0.03) (P < 0.05) indicating that the alpha-L-fucosidase present in the epididymal fluid is active on spermatozoa. Moreover, this effect was blocked with specific enzyme inhibitors. These results provide direct evidence that the alpha-L-fucosidase from epididymal fluid participates in the fucose removal from spermatozoa, as a step of sperm maturation in the bull epididymis. (C) 2017 Elsevier Inc. All rights reserved.
Nietiadi, ML ;Umstatter, P ; Alhafez, IA ; Rosandi, Y ; Bringa, EM ; Urbassek, HM ; GEOPHYSICAL RESEARCH LETTERS ,2017 ,44 ,10822 -10828 .
Collisions between ice grains are ubiquitous in the outer solar system. The mechanics of such collisions is traditionally described by the elastic contact theory of adhesive spheres. Here we use molecular dynamics simulations to study collisions between nanometer-sized amorphous water ice grains. We demonstrate that the collision-induced heating leads to grain melting in the interface of the colliding grains. The large lateral deformations and grain sticking induced considerably modify available macroscopic collision models. We report on systematic increases of the contact radius, strong grain deformations, and the prevention of grain bouncing.
Zodrow, EL ;D'Angelo, JA ; Cleal, CJ ; PALAEONTOGRAPHICA ABTEILUNG B-PALAEOPHYTOLOGIE ,2017 ,295 ,91 -133 .
The postulated relationship between chemistry and frond architecture is further tested based on a 450 mm frond segment Alethopteris ambigua Lesquereux pars from the Sydney Coalfield (Canada), this being the largest specimen known for this species. Micromorphology demonstrated amphistomatic rachides with larger anomocytic stomata than on the hypostomatic pinnules, and rachial epidermal cells that are irregularly elongate to polygonal-rectangular, intermingled with more rectangular isodiametric cells, with hardly any change over the segment. Functional groups or chemical structural groups, however, are continuously variable over the frond segment, allowing meaningful comparisons between frond parts. Based on these data, a three-dimensional "model" is derived which explains the relationship between the frond architecture and changes in chemical structural groups. Furthermore, the aromatic-rich compounds correlate with robust and stiffer proximal frond parts, whereas the aliphatic-rich compounds correlate with the slender and flexible distal parts. The former reflects lignin-related compounds in the basal part of the frond, and the latter tannin and resin-like chemicals as secondary metabolites in pinnules and midveins as the defense against herbivory. Strengthening the relationship between the hypothesized fossil chemistry-frond architecture is the testable prediction of chemistry of the "missing parts" in the likely quadripinnate A. ambigua frond, i.e. the petiole, frond bifurcation, and their adjacent proximal and most robust parts.
Marone, L ;Olmedo, M ; Valdes, DY ; Zarco, A ; de Casenave, JL ; Pol, RG ; CONDOR ,2017 ,119 ,673 -682 .
Although bird population declines associated with land degradation are common, the initial response of organisms to rapid human-induced environmental change is usually behavioral. Reductions in seed availability due to cattle grazing may trigger diet switching in seed-eating birds, but empirical examples of such behavior are lacking. We asked whether cattle grazing changed the composition and reduced the size of seed reserves, and whether seed shortage caused diet shifts in 4 species of seed-eating birds wintering in the central Monte Desert, Argentina. We assessed the soil seed bank composition and the granivorous fraction of each species' diet. Digestive tract or crop contents were obtained by using the flushing method on individuals captured with mist nets, and seeds were sorted and assigned to 1 of 3 functional groups (small grass seeds, large and medium-sized grass seeds, or forb seeds). Cattle grazing reduced the abundance of the preferred large and medium-sized grass seeds by 60-90%. The grass-seed specialists Many colored Chaco Finch (Saltatricula multicolor) and Ringed Warbling-Finch (Microspingus torquatus) did not change their diets in grazed areas, but the expanding specialists Common Diuca-Finch (Diuca diuca) and Rufous-collared Sparrow (Zonotrichia capensis) incorporated increased proportions of small grass seeds as well as forb seeds into their diets. These results were correctly predicted from species-specific differences in feeding flexibility previously established in cafeteria experiments. Based on species-specific diet composition, the energy reward of seeds by unit mass consumed decreased moderately (5-21%) in the grazed sites for S. multicolor, M. torquatus, and D. diuca. Starch content was similar between grazing conditions for all 3 birds. Although such deficits might be compensated for by a slight increase in absolute mass of seeds or alternative food items consumed in degraded lands, substantial reduction in the availability of grass seeds may reduce the capacity of degraded lands to support specialist granivorous birds.
Miranda, EN ;EUROPEAN JOURNAL OF PHYSICS ,2017 ,38 ,-.
The statistical mechanics of small clusters ( n similar to 10-50 elements) of harmonic oscillators and two-level systems is studied exactly, following the microcanonical, canonical and grand canonical formalisms. For clusters with several hundred particles, the results from the three formalisms coincide with those found in the thermodynamic limit. However, for clusters formed by a few tens of elements, the three ensembles yield different results. For a cluster with a few tens of harmonic oscillators, when the heat capacity per oscillator is evaluated within the canonical formalism, it reaches a limit value equal to k(B), as in the thermodynamic case, while within the microcanonical formalism the limit value is k(B)(1-1/n). This difference could be measured experimentally. For a cluster with a few tens of two-level systems, the heat capacity evaluated within the canonical and microcanonical ensembles also presents differences that could be detected experimentally. Both the microcanonical and grand canonical formalism show that the entropy is non-additive for systems this small, while the canonical ensemble reaches the opposite conclusion. These results suggest that the microcanonical ensemble is the most appropriate for dealing with systems with tens of particles.
Rios, JM ;Lana, NB ; Ciocco, NF ; Covaci, A ; Barrera-Oro, E ; Moreira, E ; Altamirano, JC ; ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY ,2017 ,145 ,630 -639 .
In the present study, the possible associations between selected persistent organic pollutants (POPs) and biological factors were assessed in different tissues of two Antarctic notothenioid fish: Notothenia rossii (NOR) and Trematomus newnesi (TRN) collected at Potter Cove, King George Island/Isla 25 de Mayo, South Shetland Islands. Specifically, association patterns between biological factors (body size, lipid content, body condition) and POP concentrations (polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT) and metabolites, polybrominated diphenyl ethers (PBDEs), and hexachlorocyclohexane (HCH), hexachlorobenzene (HCB), chlordanes (CHLs) and methoxylated polybrominated diphenyl ethers (MeO-PBDEs)), were explored by using two approaches: multivariate analyses (principal component analysis: PCA) and intraspecific correlations. Integrating results suggest that biological factors such as size, KI and tissue type seemed to be associated to selective accumulation of POPs for immature specimens of N. rossii, and KI and tissue type for mature specimens of T. newnesi. Each particular factor should be considered when choosing N. rossii or T. newnesi as sentinels for POPs pollution in Antarctic marine environments. Further, both nototheniids showed a selective accumulation pattern in their gonads of penta-chlorinated biphenyls (penta-CBs; 55.5 and 29 ng g(-1) lw for N. rossii and T. newnesi, respectively) and organochlorine pesticides such as DDTs (199 and 13.3 ng g(-1) lw, for N. rossii and T. newnesi respectively), and of polybrominated diphenyl ethers (PBDEs) in gills (97.2 and 22.1 for ng g(-1) lw, for N. rossii and T. newnesi, respectively), highlighting the importance of these tissues in monitoring studies of pollution in fish. The current study expands the knowledge concerning the biological factors to be investigated when specific pollutants are monitored and supports the importance of tissue type for the selective accumulation of POPs in Antarctic fish. Additionally, a contribution to the scarce data on concentration of MeO-PBDEs in Antarctic marine organisms, particularly in the highly diverse perciform suborder Notothenioidei is provided.
Peralta, G ;Stevani, EL ; Chacoff, NP ; Dorado, J ; Vazquez, DP ; JOURNAL OF ANIMAL ECOLOGY ,2017 ,86 ,1372 -1379 .
Fire represents a frequent disturbance in many ecosystems, which can affect plant-pollinator assemblages and hence the services they provide. Furthermore, fire events could affect the architecture of plant-pollinator interaction networks, modifying the structure and function of communities.
Planes, MB ;Millan, EN ; Urbassek, HM ; Bringa, EM ; ASTRONOMY & ASTROPHYSICS ,2017 ,607 ,-.
Context. Dust impact into granular materials leads to crater formation and material ejection. Aims. The impact of dust aggregates, composed of a number Np of grains, into a granular bed consisting of the same grains is studied as a function of impact velocity v and projectile size Np. No gravitational effects are included.
Anderson, DC ;Nicely, JM ; Wolfe, GM ; Hanisco, TF ; Salawitch, RJ ; Canty, TP ; Dickerson, RR ; Apel, EC ; Baidar, S ; Bannan, TJ ; Blake, NJ ; Chen, DX ; Dix, B ; Fernandez, RP ; Hall, SR ; Hornbrook, RS ; Huey, LG ; Josse, B ; Jockel, P ; Kinnison, DE ; Koenig, TK ; Le Breton, M ; Marecal, V ; Morgenstern, O ; Oman, LD ; Pan, LL ; Percival, C ; Plummer, D ; Revell, LE ; Rozanov, E ; Saiz-Lopez, A ; Stenke, A ; Sudo, K ; Tilmes, S ; Ullmann, K ; Volkamer, R ; Weinheimer, AJ ; Zeng, G ; JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES ,2017 ,122 ,11201 -11226 .
Formaldehyde (HCHO) directly affects the atmospheric oxidative capacity through its effects on HOx. In remote marine environments, such as the tropical western Pacific (TWP), it is particularly important to understand the processes controlling the abundance of HCHO because model output from these regions is used to correct satellite retrievals of HCHO. Here we have used observations from the Convective Transport of Active Species in the Tropics (CONTRAST) field campaign, conducted during January and February 2014, to evaluate our understanding of the processes controlling the distribution of HCHO in the TWP as well as its representation in chemical transport/climate models. Observed HCHO mixing ratios varied from similar to 500 parts per trillion by volume (pptv) near the surface to similar to 75 pptv in the upper troposphere. Recent convective transport of near surface HCHO and its precursors, acetaldehyde and possibly methyl hydroperoxide, increased upper tropospheric HCHO mixing ratios by similar to 33% (22 pptv); this air contained roughly 60% less NO than more aged air. Output from the CAM-Chem chemistry transport model (2014 meteorology) as well as nine chemistry climate models from the Chemistry-Climate Model Initiative (free-running meteorology) are found to uniformly underestimate HCHO columns derived from in situ observations by between 4 and 50%. This underestimate of HCHO likely results from a near factor of two underestimate of NO in most models, which strongly suggests errors in NOx emissions inventories and/or in the model chemical mechanisms. Likewise, the lack of oceanic acetaldehyde emissions and potential errors in the model acetaldehyde chemistry lead to additional underestimates in modeled HCHO of up to 75 pptv (similar to 15%) in the lower troposphere.
Zarco, A ;Cueto, VR ; ARDEA ,2017 ,105 ,89 -97 .
Flocking behaviour has been studied for decades around the world, but there is little knowledge of this subject in desert bird communities. We investigate winter flock structure in open woodlands of the central Monte desert, Argentina, during two consecutive years. Of the 22 bird species that were recorded in flocks, most were granivorous. There were differences in flock density between years, probably due to fluctuation in seed abundance. More than half of the observed flocks were composed of different species (i.e. mixed-species flocks). We detected only two regular species (found in more than 75% of flocks): Rufous-collared Sparrow Zonotrichia capensis and Ringed Warbling Finch Poospiza torquata, both granivorous birds. Ringed Warbling Finch and Cinnamon Warbling Finch Poospiza ornata co-occurred at a higher frequency than expected by chance, and formed subgroups within flocks. Many-colored Chaco Finch Saltatricula multicolor, Greater Wagtail-tyrant Stigmatura budytoides, Brown Cacholote Pseudoseisura lophotes and Short-billed Canastero Asthenes baeri were found to form family groups, which may be related to delayed natal dispersal. The observed flocking propensity of granivorous birds and the small number of species per flock were similar to that found in other desert bird communities. We discuss some differences and similarities between granivorous and insectivorous flocking patterns, and propose hypotheses on the plausible causes. Our results provide a basis for a better understanding of the flocking behaviour patterns of birds in arid environments.
Ruestes, CJ ;Alhafez, IA ; Urbassek, HM ; CRYSTALS ,2017 ,7 ,-.
This review covers areas where our understanding of the mechanisms underlying nanoindentation has been increased by atomistic studies of the nanoindentation process. While such studies have been performed now for more than 20 years, recent investigations have demonstrated that the peculiar features of nanoplasticity generated during indentation can be analyzed in considerable detail by this technique. Topics covered include: nucleation of dislocations in ideal crystals, effect of surface orientation, effect of crystallography (fcc, bcc, hcp), effect of surface and bulk damage on plasticity, nanocrystalline samples, and multiple (sequential) indentation. In addition we discuss related features, such as the influence of tip geometry on the indentation and the role of adhesive forces, and how pre-existing plasticity affects nanoindentation.
Carvelli, L ;Yuan, LB ; Esfandnia, S ; Zhang, Y ; Presley, JF ; Morales, CR ; HISTOLOGY AND HISTOPATHOLOGY ,2017 ,32 ,1017 -1027 .
A number of pathogens for which there are no effective treatments infect the cells via endocytosis. Once in the endosomes, the pathogens complete their life cycle by overriding normal lysosomal functions. Recently, our laboratory identified the lysosomal targeting signal of prosaposin, which is recognized by the sorting receptor "sortilin". Based on this evidence, we tested whether the antimicrobial peptide beta-Defensin linked to the targeting sequence of prosaposin (beta D-PSAP) could be redirected from its secretory pathway to the endolysosomal compartment. To this effect, beta D-PSAP was transfected into COS-7 cells. The sub-cellular distribution of beta D-PSAP was analyzed by confocal microscopy and differential centrifugation. Confocal microscopy demonstrated that beta D-PSAP overlaid with the lysosomal marker LAMP1, indicating that the construct reached endosomes and lysosomes. Differential centrifugation also showed that beta D-PSAP was in the lysosomal fractions. In addition, our binding inhibition assay demonstrated that beta D-PSAP bound specifically to sortilin. Similarly, the delivery of beta D-PSAP was abolished after overexpressing a truncated sortilin. These results indicate that the prosaposin C-terminus and D/C-domain (prosaposin targeting sequence) was an effective "guidance system" to redirect beta D-PSAP to the endolysosomal compartment. In the future, this and other fusion proteins with antimicrobial properties will be assembled to our "biotic vehicle" to target pathogens growing within these compartments.
Barberena, R ;Duran, VA ; Novellino, P ; Winocur, D ; Benitez, A ; Tessone, A ; Quiroga, MN ; Marsh, EJ ; Gasco, A ; Cortegoso, V ; Lucero, G ; Llano, C ; Knudson, KJ ; AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY ,2017 ,164 ,305 -320 .
ObjectivesThe goal of this article is to assess the scale of human paleomobility and ecological complementarity between the lowlands and highlands in the southern Andes during the last 2,300 years. By providing isotope results for human bone and teeth samples, we assess a hypothesis of high residential mobility suggested on the basis of oxygen isotopes from human remains.
Paz, RC ;Kozaczek, ME ; Rosli, HG ; Andino, NP ; Sanchez-Puerta, MV ; GENETICA ,2017 ,145 ,417 -430 .
Transposable elements are the most abundant components of plant genomes and can dramatically induce genetic changes and impact genome evolution. In the recently sequenced genome of tomato (Solanum lycopersicum), the estimated fraction of elements corresponding to retrotransposons is nearly 62%. Given that tomato is one of the most important vegetable crop cultivated and consumed worldwide, understanding retrotransposon dynamics can provide insight into its evolution and domestication processes. In this study, we performed a genome-wide in silico search of full-length LTR retroelements in the tomato nuclear genome and annotated 736 full-length Gypsy and Copia retroelements. The dispersion level across the 12 chromosomes, the diversity and tissue-specific expression of those elements were estimated. Phylogenetic analysis based on the retrotranscriptase region revealed the presence of 12 major lineages of LTR retroelements in the tomato genome. We identified 97 families, of which 77 and 20 belong to the superfamilies Copia and Gypsy, respectively. Each retroelement family was characterized according to their element size, relative frequencies and insertion time. These analyses represent a valuable resource for comparative genomics within the Solanaceae, transposon-tagging and for the design of cultivar-specific molecular markers in tomato.
Arcos, A ;de Paola, M ; Gianetti, D ; Acuna, D ; Velasquez, ZD ; Miro, MP ; Toro, G ; Hinrichsen, B ; Munoz, RI ; Lin, Y ; Mardones, GA ; Ehrenfeld, P ; Rivera, FJ ; Michaut, MA ; Batiz, LF ; SCIENTIFIC REPORTS ,2017 ,7 ,-.
The balance between ovarian folliculogenesis and follicular atresia is critical for female fertility and is strictly regulated by a complex network of neuroendocrine and intra-ovarian signals. Despite the numerous functions executed by granulosa cells (GCs) in ovarian physiology, the role of multifunctional proteins able to simultaneously coordinate/modulate several cellular pathways is unclear. Soluble N-ethylmaleimide-sensitive factor (NSF) attachment protein (alpha-SNAP) is a multifunctional protein that participates in SNARE-mediated membrane fusion events. In addition, it regulates cell-to-cell adhesion, AMPK signaling, autophagy and apoptosis in different cell types. In this study we examined the expression pattern of a-SNAP in ovarian tissue and the consequences of alpha-SNAP (M105I) mutation (hyh mutation) in folliculogenesis and female fertility. Our results showed that alpha-SNAP protein is highly expressed in GCs and its expression is modulated by gonadotropin stimuli. On the other hand, a-SNAP-mutant mice show a reduction in a-SNAP protein levels. Moreover, increased apoptosis of GCs and follicular atresia, reduced ovulation rate, and a dramatic decline in fertility is observed in a-SNAP-mutant females. In conclusion, a-SNAP plays a critical role in the balance between follicular development and atresia. Consequently, a reduction in its expression/function (M105I mutation) causes early depletion of ovarian follicles and female subfertility.
Rivera, A ;Olivares, J ; Prada, A ; Crespillo, ML ; Caturla, MJ ; Bringa, EM ; Perlado, JM ; Pena-Rodriguez, O ; SCIENTIFIC REPORTS ,2017 ,7 ,-.
The irradiation of silica with ions of specific energy larger than similar to 0.1 MeV/u produces very high electronic excitations that induce permanent changes in the physical, chemical and structural properties and give rise to defects (colour centres), responsible for the loss of sample transparency at specific bands. This type of irradiation leads to the generation of nanometer-sized tracks around the ion trajectory. In situ optical reflection measurements during systematic irradiation of silica samples allowed us to monitor the irradiation-induced compaction, whereas ex situ optical absorption measurements provide information on colour centre generation. In order to analyse the results, we have developed and validated an atomistic model able to quantitatively explain the experimental results. Thus, we are able to provide a consistent explanation for the size of the nanotracks, the velocity and thresholding effects for track formation, as well as, the colour centre yield per ion and the colour centre saturation density. In this work we will discuss the different processes involved in the permanent modification of silica: collective atomic motion, bond breaking, pressure-driven atom rearrangement and ultra-fast cooling. Despite the sudden lattice energy rise is the triggering and dominant step, all these processes are important for the final atomic configuration.
Holz, A ;Paritsis, J ; Mundo, IA ; Veblen, TT ; Kitzberger, T ; Williamson, GJ ; Araoz, E ; Bustos-Schindler, C ; Gonzalez, ME ; Grau, HR ; Quezada, JM ; PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF ,2017 ,114 ,9552 -9557 .
The Southern Annular Mode (SAM) is the main driver of climate variability at mid to high latitudes in the Southern Hemisphere, affecting wildfire activity, which in turn pollutes the air and contributes to human health problems and mortality, and potentially provides strong feedback to the climate system through emissions and land cover changes. Here we report the largest Southern Hemisphere network of annually resolved tree ring fire histories, consisting of 1,767 fire-scarred trees from 97 sites (from 22 05 to 54 05) in southern South America (SAS), to quantify the coupling of SAM and regional wildfire variability using recently created multicentury proxy indices of SAM for the years 1531-2010 AD. We show that at interannual time scales, as well as at multidecadal time scales across 37-54 degrees s, latitudinal gradient elevated wildfire activity is synchronous with positive phases of the SAM over the years 1665-1995. Positive phases of the SAM are associated primarily with warm conditions in these biomass-rich forests, in which widespread fire activity depends on fuel desiccation. Climate modeling studies indicate that greenhouse gases will force SAM into its positive phase even if stratospheric ozone returns to normal levels, so that climate conditions conducive to widespread fire activity in SAS will continue throughout the 21st century.
Mundo, IA ;Villalba, R ; Veblen, TT ; Kitzberger, T ; Holz, A ; Paritsis, J ; Ripalta, A ; ECOSPHERE ,2017 ,8 ,-.
Fire is a major disturbance affecting forests worldwide with significant economic, social, and ecological impacts. The southernmost forests on Earth extend continuously along the Andes from mid-to subantarctic latitudes in South America. In this region, warming and drying trends since the mid-20th century have been linked to a positive trend in the Southern Annual Mode (SAM), the leading mode of extratropical climate variability in the Southern Hemisphere. Due to the scarcity of documentary fire records and the lack of tree-ring fire histories, little is known about how wildfire activity responds to shifts in the westerly circulation pattern and associated climatic variability in the Andean region south of similar to 44 degrees S. For the first time, we applied dendrochronological techniques to reconstruct fire history from the angiosperm Nothofagus pumilio at 16 sites distributed from similar to 44 degrees to 50 degrees S to determine relationships between fire occurrence and the two primary drivers of wildfire activity: climate variability and human activities. Partial cross-sections with fire scars were collected from 363 trees in Argentina and Chile. Chronologies of annually resolved fire-scar dates start in 1791 and show a pattern of higher fire frequency during the 20th century, concurrent with the human occupation and colonization processes in southern Patagonia. Years of widespread fire occurring synchronously in two or more disjunct sites are associated with broad-scale climatic anomalies. Intense droughts inferred from extreme departures in temperature, precipitation, and the Standardized Precipitation-Evapotranspiration Index (SPEI) during the growing seasons of 1944 and 1962 are consistent with the two most severe fires at northern sites. Extended droughts, reflected by the association of fire occurrence with six-month cumulative precipitation and SPEI, create conditions for widespread fires at the southern sites (south of similar to 46 degrees S). Regional fires were concurrent with significant positive departures of SAM during the austral spring-summer. This tree-ring fire record reveals the influences of both climate variability and human activities on fire in the N. pumilio forests across the Andes, and also establishes the feasibility of using this tree species as a natural archive of fire history.
Guida-Johnson, B ;Zuleta, GA ; AMBIO ,2017 ,46 ,578 -587 .
In the present context of global change and search for sustainability, we detected a gap between restoration and society: local communities are usually only considered as threats or disturbances when planning for restoration. To bridge this gap, we propose a landscape design framework for planning riparian rehabilitation in an urban-rural gradient. A spatial multi-criteria analysis was used to assess the priority of riversides by considering two rehabilitation objectives simultaneously-socio-environmental and ecological-and two sets of criteria were designed according to these objectives. The assessment made it possible to identify 17 priority sites for riparian rehabilitation that were associated with different conditions along the gradient. The double goal setting enabled a dual consideration of citizens, both as beneficiaries and potential impacts to rehabilitation, and the criteria selected incorporated the multi-dimensional nature of the environment. This approach can potentially be adapted and implemented in any other anthropic-natural interface throughout the world.
Gimenez, VMM ;Ruiz-Roso, MB ; Camargo, AB ; Kassuha, D ; Manucha, W ; CLINICA E INVESTIGACION EN ARTERIOSCLEROSIS ,2017 ,29 ,224 -230 .
Atherosclerosis, a known and prevalent disease, causes progressive deterioration of affected vessels, inducing a blood flow reduction with different complications, and its symptoms usually manifest in advanced stages of the disease. Therefore, the classic therapeutic alternatives are insufficient because the damages are many times irreversible. For this reason, there is a need to implement intelligent forms of drug administration and develop new therapeutic targets that reduce the progression of atherosclerotic lesion. The implementation of new tools for prevention, diagnosis and treatment of this cardiovascular disease is of special interest, focusing our attention on achieving a more effective control of the immune system. Finally, this review highlights the latest knowledge about nanotechnology as a powerful, modern, and promising therapeutic alternative applied to atherosclerotic disease, as well as warning of the potential complications with their use. (C) 2016 Sociedad Espanola de Arteriosclerosis. Published by Elsevier Espana, S.L.U. All rights reserved.
Millan, EN ;Wolovick, N ; Piccoli, MF ; Garino, CG ; Bringa, EM ; CLUSTER COMPUTING-THE JOURNAL OF NETWORKS SOFTWARE TOOLS AND ,2017 ,20 ,2763 -2777 .
Cellular automata (CA) models are of interest to several scientific areas, and there is a growing interest in exploring large systems which would need high performance computing. In this work a CA implementation is presented which performs well in five different NVIDIA GPU architectures, from Tesla to Maxwell, simulating systems with up to a billion cells. Using the game of life (GoL) and a more complex variation of GoL as examples, a performance of 5.58e6 evaluated cells/s is achieved. The two optimizations most often used in previous studies are the use of shared memory and Multicell algorithms. Here, these optimizations do not improve performance in Fermi or newer architectures. The GoL CA code running in an NVIDIA Titan X obtained a speedup of up to similar to 85 x and up to similar to 230 x for a more complex CA, compared to an optimized serial CPU implementation. Finally, the efficiency of each GPU is analyzed in terms of cell performance/transistors and cell performance/bandwidth showing how the architectures improved for this particular problem.
Vanni, G ;Escudero, LB ; Dotto, GL ; WATER SCIENCE AND TECHNOLOGY ,2017 ,76 ,1177 -1187 .
An alternative, low-cost and efficient biosorbent, powdered grape seeds (PGS), was prepared from wastes of a wine industry, and used to remove brilliant blue (BB) and amaranth red (AR) dyes from aqueous solutions. The biosorbent was properly characterized before and after the biosorption operation. The potential of PGS to remove BB and AR dyes was investigated thought kinetic, isotherm and thermodynamic studies. The biosorption of BB and AR was favored at pH 1.0 using biosorbent dosage of 0.500 g L-1, being attained more than 85% of removal percentage. For BB and AR dyes, pseudo-second-order and Elovich models were able to explain the biosorption kinetic. The biosorption equilibrium of BB on PGS was well represented by the Langmuir model, while for AR, the Sips model was the most adequate. The maximum biosorption capacities were 599.5 and 94.2 mg g(-1) for BB and AR, respectively. The biosorption of BB and AR on PGS was a spontaneous, favorable and endothermic process. These findings indicated that PGS is a low-cost and efficient biosorbent, which can be used to treat dye containing waters.
Valencia, FJ ;Gonzalez, RI ; Valdivia, JA ; Kiwi, M ; Bringa, EM ; Rogan, J ; JOURNAL OF PHYSICAL CHEMISTRY C ,2017 ,121 ,17856 -17861 .
The large surface-to-volume ratio of hollow palladium nanoparticles (hNPs) offers room to improve their hydrogen storage capacity as well as their catalytic activity. However, a less explored possibility is to use, in addition, the internal cavity. Here we explore, through classical molecular dynamics, the possibility of boring channels across the hNP wall by collision with solid Pd nanoprojectiles at high velocities, as well as their resilience to maintain their spherical geometry. We choose a stable hNP with an inner diameter of 13 nm and an outer diameter of 15 nm. The projectiles are Pd NPs of 1.5, 2.4, and 3.0 nm, respectively. We consider collision speeds between 3 and 15 km/s, with an impact parameter between 0 to 7 nm. Four different regimes, as a function of kinetic energy and impact parameter of the projectile, are found. For low speeds, the projectile is not able to penetrate the target and only creates surface craters. For a narrow range of intermediate speeds, the projectile enters the target, but the hNP shell is able to self-heal, either totally or partially. For large speeds, the projectile penetrates the target without altering its spherical hollow geometry, but for even larger speeds, the hNP collapses into a solid structure. The specific threshold speed for each regime depends on the mass and speed of the projectile. In all noncollapsing cases, the results show a linear relationship between projectile kinetic energy and crater or perforation size. We also studied its behavior when the hNP suffers successive collisions, finding that it keeps its hollow shape but forms faceted structures, such as nanoframes or hollow cuboctahedron nanoparticles. All of our results suggest that Pd hNPs, with adequate combinations of external radius and thickness are very robust, can withstand hypervelocity impacts and that channels can be opened to allow molecules to reach the internal cavity.
Navarro, MA ;Saiz-Lopez, A ; Cuevas, CA ; Fernandez, RP ; Atlas, E ; Rodriguez-Lloveras, X ; Kinnison, D ; Lamarque, JF ; Tilmes, S ; Thornberry, T ; Rollins, A ; Elkins, J ; Hintsa, EJ ; Moore, FL ; ATMOSPHERIC CHEMISTRY AND PHYSICS ,2017 ,17 ,9917 -9930 .
The stratospheric inorganic bromine (Br-y)burden arising from the degradation of brominated very short-lived organic substances (VSLorg) and its partitioning between reactive and reservoir species is needed for a comprehensive assessment of the ozone depletion potential of brominated trace gases. Here we present modeled inorganic bromine abundances over the Pacific tropical tropopause based on aircraft observations of VSLorg from two campaigns of the Airborne Tropical TRopopause EXperiment (ATTREX 2013, carried out over the eastern Pacific, and ATTREX 2014, carried out over the western Pacific) and chemistry-climate simulations (along ATTREX flight tracks) using the specific meteorology prevailing. Using the Community Atmosphere Model with Chemistry (CAM-Chem) we model that BrO and Br are the daytime dominant species. Integrated across all ATTREX flights, BrO represents similar to 43 and 48% of daytime Bry abundance at 17 km over the western and eastern Pacific, respectively. The results also show zones where Br / BrO > 1 depending on the solar zenith angle (SZA), ozone concentration, and temperature. On the other hand, BrCl and BrONO2 were found to be the dominant nighttime species with similar to 61 and 56% of abundance at 17 km over the western and eastern Pacific, respectively. The western-to-eastern differences in the partitioning of inorganic bromine are explained by different abundances of ozone (O-3), nitrogen dioxide (NO2), total inorganic chlorine (Cl-y), and the efficiency of heterogeneous reactions of bromine reservoirs (mostly BrONO2 and HBr) occurring on ice crystals.
Lisandrini, FT ;Lobos, AM ; Dobry, AO ; Gazza, CJ ; PHYSICAL REVIEW B ,2017 ,96 ,-.
We study, by means of the density-matrix renormalization group (DMRG) technique, the evolution of the ground state in a one-dimensional topological insulator, from the noninteracting to the strongly interacting limit, where the system can be mapped onto a topological Kondo-insulator model. We focus on a toy model Hamiltonian ( i.e., the interacting "sp-ladder" model), which could be experimentally realized in optical lattices with higher orbitals loaded with ultracold fermionic atoms. Our goal is to shed light on the emergence of the strongly interacting ground state and its topological classification as the Hubbard U interaction parameter of the model is increased. Our numerical results show that the ground state can be generically classified as a symmetry-protected topological phase of the Haldane type, even in the noninteracting case U = 0 where the system can be additionally classified as a time-reversal Z(2)-topological insulator, and evolves adiabatically between the noninteracting and strongly interacting limits.
Gatica, MG ;Aranibar, JN ; Pucheta, E ; AUSTRAL ECOLOGY ,2017 ,42 ,533 -543 .
Spatial variation in mean annual precipitation is the principal driver of plant water and nitrogen status in drylands. The natural abundance of carbon stable isotopes (delta C-13) in photosynthetic tissues of C3 plants is an indicator of time-integrated behaviour of stomatal conductance; while that of nitrogen stable isotopes (delta N-15) is an indicator of the main source of plant N (soil N vs. atmospheric N-2). Previous studies in drylands have documented that plant delta C-13 and delta N-15 values increase with decreasing mean annual precipitation due to reductions in stomatal conductance, and soil enriched in N-15, respectively. However, evidence for this comes from studies focused on stable isotopes measurements integrated at the plant community level or on dominant plants at the site level, but little effort has been made to study C and N isotope variations within a species growing along rainfall gradients. We analysed plant delta C-13, delta N-15 and C/N values of three woody species having different phenological leaf traits (deciduous, perennial and aphyllous) along a regional mean annual precipitation gradient from the central-western Argentinian drylands. Noticeably, plant delta C-13 and delta N-15 values in the three woody species did not increase towards sites with low precipitation or at the start of the growing season (drier period), as we expected. These results suggest that environmental factors other than mean annual precipitation may be affecting plant delta C-13 and delta N-15. The short-term environmental conditions may interact with species-specific plant traits related to water and nitrogen use strategies and override the predictive influence of the mean annual precipitation on plant delta C-13 and delta N-15 widely reported in drylands.
Ramirez, DA ;Locatelli, DA ; Gonzalez, RE ; Cavagnaro, PF ; Camargo, AB ; JOURNAL OF FOOD COMPOSITION AND ANALYSIS ,2017 ,61 ,4 -19 .
Plant organosulfur compounds represent one of the main groups of phytochemicals that evidence an ample spectrum of biological activities. There are two major sources of sulfur-containing compounds in plant foods; Allium vegetables, such as garlic, onion, and leek; and cruciferous vegetables, such as broccoli, cabbage, and cauliflower. Among them, garlic is the most studied species, mainly due to the multiple health-enhancing effects attributed to its consumption. Most of these properties have been attributed to organosulfur compounds. Thus, knowledge on the analytical determinations available for the main bioactive sulfur compounds in Allium is of interest. In the present review, an extensive bibliographic survey was performed to compile information regarding the different methodologies that can be used for the determination of alk(en)yl cysteine sulfoxides (ACSOs), S-allyl cysteine (SAC), thiosulfinates (mainly allicin), diallyl, mono- di-, and tri-sulfides, vinyldithiins and (E)- and (Z)-ajoene, as influenced by plant matrices and other factors. The gathered information was analyzed and presented in a systemic and comparative way, describing advantages and disadvantages of the methodologies, considering both extractive and separative techniques, the type of matrices, columns and analytical performance data. In addition, new trends and future prospects for the analysis of sulfur compounds in plants were critically discussed. (C) 2016 Elsevier Inc. All rights reserved.
Sedeno, L ;Piguet, O ; Abrevaya, S ; Desmaras, H ; Garcia-Cordero, I ; Baez, S ; de la Fuente, LA ; Reyes, P ; Tu, SC ; Moguilner, S ; Lori, N ; Landin-Romero, R ; Matallana, D ; Slachevsky, A ; Torralva, T ; Chialvo, D ; Kumfor, F ; Garcia, AM ; Manes, F ; Hodges, JR ; Ibanez, A ; HUMAN BRAIN MAPPING ,2017 ,38 ,3804 -3822 .
Biomarkers represent a critical research area in neurodegeneration disease as they can contribute to studying potential disease-modifying agents, fostering timely therapeutic interventions, and alleviating associated financial costs. Functional connectivity (FC) analysis represents a promising approach to identify early biomarkers in specific diseases. Yet, virtually no study has tested whether potential FC biomarkers prove to be reliable and reproducible across different centers. As such, their implementation remains uncertain due to multiple sources of variability across studies: the numerous international centers capable conducting FC research vary in their scanning equipment and their samples' socio-cultural background, and, more troublingly still, no gold-standard method exists to analyze FC. In this unprecedented study, we aim to address both issues by performing the first multicenter FC research in the behavioral-variant frontotemporal dementia (bvFTD), and by assessing multiple FC approaches to propose a gold-standard method for analysis. We enrolled 52 bvFTD patients and 60 controls from three international clinics (with different fMRI recording parameters), and three additional neurological patient groups. To evaluate FC, we focused on seed analysis, inter-regional connectivity, and several graph-theory approaches. Only graph-theory analysis, based on weighted-matrices, yielded consistent differences between bvFTD and controls across centers. Also, graph metrics robustly discriminated bvFTD from the other neurological conditions. The consistency of our findings across heterogeneous contexts highlights graph-theory as a potential gold-standard approach for brain network analysis in bvFTD. Hum Brain Mapp 38:3804-3822, 2017. (c) 2017 Wiley Periodicals, Inc.
Valencia, FJ ;Gonzalez, RI ; Bringa, EM ; Kiwi, M ; CARBON ,2017 ,119 ,219 -224 .
Hillock formation on nanocrystalline (nc) diamond under swift heavy ion irradiation is studied by means of classical molecular dynamics. The irradiation is simulated by means of a thermal spike model, the nc samples include as many as 5 millions atoms. Our results show that hillocks on nc diamond can be created for stopping powers (SPe) in the range of 12-17 keV/nm, and grain sizes less than 13 nm. For smaller values of the SPe only point defects are observed on the nc surface, while for larger SPe hillocks suffer a transition to crater-rim, because of the increased sputtering that is due to the large energy that the ions deposit. We observe that the sputtering yields depend quadratically on the stopping power, contrary to what has been obtained by simulations for some single crystal solids. In addition, our results show that hillocks are smaller for 5 and 7 nm grain sizes, due to the large free volume that is available on the grain boundaries. Instead, for 10 and 13 nm the hillock is limited only to the amorphization of the grain closest to the surface. No hillock formation is expected for larger grain sizes, because of the transition of the nc to pristine diamond, where no hillock formation has been observed. (C) 2017 Elsevier Ltd. All rights reserved.
Arbocco, FCV ;Persia, FA ; Hapon, MB ; Jahn, GA ; MOLECULAR AND CELLULAR ENDOCRINOLOGY ,2017 ,450 ,14 -23 .
Thyroid pathologies have deleterious effects on lactation. Especially hypothyroidism (HypoT) induces premature mammary involution at the end of lactation and decreases milk production and quality in mid lactation. Milk synthesis is controlled by JAK2/STAT5 signaling pathway and prolactin (PRL), which activates the pathway. In this work we analyzed the effect of chronic 6-propyl-2-thiouracil (PTU)-induced HypoT on PRL signaling pathway on mammary glands from rats on lactation (L) days 2, 7 and 14. HypoT decreased prolactin receptor expression, and expression and activation of Stat5a/b protein. Expression of members of the SOCS-CIS family, inhibitors of the JAK-STAT pathway, decreased in L2 and L7, possibly as a compensatory response of the mammary cells to maintain PRL responsiveness. However, on L14, the level of these inhibitors was normal and the transcription of alpha-lactoalbumin (lalba), a target gene of the PRL pathway, decreased by half. HypoT altered the transcriptional capacity of the cell and decreased mRNA levels of Prlr and Stat5b on L14. Stat5b gene has functional thyroid hormone response elements in the regulatory regions, that bind thyroid hormone receptor beta (TR beta) differentially and in a thyroid hormone dependent manner. The overall decrease in the PRL signaling pathway and consequently in target gene (lalba) mRNA transcription explain the profound negative impact of HypoT on mammary function through lactation. (C) 2017 Elsevier B.V. All rights reserved.
Emile-Geay, J ;McKay, NP ; Kaufman, DS ; von Gunten, L ; Wang, JG ; Anchukaitis, KJ ; Abram, NJ ; Addison, JA ; Curran, MAJ ; Evans, MN ; Henley, BJ ; Hao, ZX ; Martrat, B ; McGregor, HV ; Neukom, R ; Pederson, GT ; Stenni, B ; Thirumalai, K ; Werner, JP ; Xu, CX ; Divine, DV ; Dixon, BC ; Gergis, J ; Mundo, IA ; Nakatsuka, T ; Phipps, SJ ; Routson, CC ; Steig, EJ ; Tierney, JE ; Tyler, JJ ; Allen, KJ ; Bertler, NAN ; Bjorklund, J ; Chase, BM ; Chen, MT ; Cook, E ; de Jong, R ; DeLong, KL ; Dixon, DA ; Ekaykin, AA ; Ersek, V ; Filipsson, HL ; Francus, P ; Freund, MB ; Frezzotti, M ; Gaire, NP ; Gajewski, K ; Ge, QS ; Goosse, H ; Gornostaeva, A ; Grosjean, M ; Horiuchi, K ; Hormes, A ; Husum, K ; Isaksson, E ; Kandasamy, S ; Kawamura, K ; Kilbourne, KH ; Koc, N ; Leduc, G ; Linderholm, HW ; Lorrey, AM ; Mikhalenko, V ; Mortyn, PG ; Motoyama, H ; Moy, AD ; Mulvaney, R ; Munz, PM ; Nash, DJ ; Oerter, H ; Opel, T ; Orsi, AJ ; Ovchinnikov, DV ; Porter, TJ ; Roop, HA ; Saenger, C ; Sano, M ; Sauchyn, D ; Saunders, KM ; Seidenkrantz, MS ; Severi, M ; Shao, XM ; Sicre, MA ; Sigl, M ; Sinclair, K ; St George, S ; St Jacques, JM ; Thamban, M ; Thapa, UK ; Thomas, ER ; Turney, C ; Uemura, R ; Viau, AE ; Vladimirova, DO ; Wahl, ER ; White, JWC ; Yu, ZC ; Zinke, J ; SCIENTIFIC DATA ,2017 ,4 ,-.
Reproducible climate reconstructions of the Common Era (1 CE to present) are key to placing industrial-era warming into the context of natural climatic variability. Here we present a community-sourced database of temperature-sensitive proxy records from the PAGES2k initiative. The database gathers 692 records from 648 locations, including all continental regions and major ocean basins. The records are from trees, ice, sediment, corals, speleothems, documentary evidence, and other archives. They range in length from 50 to 2000 years, with a median of 547 years, while temporal resolution ranges from biweekly to centennial. Nearly half of the proxy time series are significantly correlated with HadCRUT4.2 surface temperature over the period 1850-2014. Global temperature composites show a remarkable degree of coherence between high-and low-resolution archives, with broadly similar patterns across archive types, terrestrial versus marine locations, and screening criteria. The database is suited to investigations of global and regional temperature variability over the Common Era, and is shared in the Linked Paleo Data (LiPD) format, including serializations in Matlab, R and Python.
Nietiadi, ML ;Umstatter, P ; Tjong, T ; Rosandi, Y ; Millan, EN ; Bringa, EM ; Urbassek, HM ; PHYSICAL CHEMISTRY CHEMICAL PHYSICS ,2017 ,19 ,16555 -16562 .
Using molecular dynamics simulations, we study collisions between amorphous silica nanoparticles. Our silica model contains uncontaminated surfaces, that is, the effect of surface hydroxylation or of adsorbed water layers is excluded. For central collisions, we characterize the boundary between sticking and bouncing collisions as a function of impact velocity and particle size and quantify the coefficient of restitution. We show that the traditional Johnson-Kendall-Roberts (JKR) model provides a valid description of the ingoing trajectory of two grains up to the moment of maximum compression. The distance of closest approach is slightly underestimated by the JKR model, due to the appearance of plasticity in the grains, which shows up in the form of localized shear transformation zones. The JKR model strongly underestimates the contact radius and the collision duration during the outgoing trajectory, evidencing that the breaking of covalent bonds during grain separation is not well described by this model. The adhesive neck formed between the two grains finally collapses while creating narrow filaments joining the grains, which eventually tear.
Grossi, J ;Kohanoff, JJ ; English, NJ ; Bringa, EM ; Del Popolo, MG ; JOURNAL OF PHYSICAL CHEMISTRY B ,2017 ,121 ,6436 -6441 .
Efficient charge transport has been observed in iodide-based room-temperature ionic liquids when doped with iodine. To investigate preferred pathways for the iodide (I-)-to-triiodide (I-3(-)) exchange reaction and to clarify the origin of this high ionic conductivity, we have conducted electronic structure calculations in the crystal state of 1-butyl-3methylimidazolium iodide ([BMIM] [I]). Energy barriers for the different stages of the iodine-swapping process, including the reorientation of the I-center dot center dot center dot I3- moiety, were determined from minimum energy paths as a function of a reaction coordinate. Hirshfeld charges and structural parameters, such as bond lengths and angles, were monitored during the reaction. Several bond exchange events were observed with energy barriers ranging from 0.17 to 0.48 eV and coinciding with the formation of a twisted I-center dot center dot center dot I-3(-) complex. Striking similarities were observed in the mechanics and energetics of this charge-transfer process in relation to solid-state superionic conductors.
Katzer, L ;Zumbo, PG ; Chiavazza, H ; Gasull, VM ; Velez, S ; RELACIONES ,2017 ,42 ,345 -367 .
In the Latin American and Argentinean scientific imaginary, nomadic life forms lack current existence. However, the ethnographic records of Lavalle's dryland show the opposite. The following article proposes to analyze the social and cultural mechanisms through which the ethnic ascripts construct territoriality and structure their forms of sociability on the basis of a reactivated nomadism, based on an interdisciplinary reading from ecology, archeology and ethnography. We approach the territorial production in the NE of Mendoza in a multidimensional way proposing as a central hypothesis that native forms of sociability tend to activate and give continuity in a reconfigured and updated way, the historical forms of nomadism (archaeologically and ethno historically recorded) in these dimensions Work, residence and management of local natural resources.
Romero, G ;Barberena, R ; RELACIONES ,2017 ,42 ,369 -377 .
Monge, DA ;Gari, Y ; Mateos, C ; Garino, CG ; COMPUTER SYSTEMS SCIENCE AND ENGINEERING ,2017 ,32 ,291 -306 .
Autoscaling strategies achieve efficient and cheap executions of scientific workflows running in the cloud by determining appropriate type and amount of virtual machine instances to use while scheduling the tasks/data. Current strategies only consider on-demand instances ignoring the advantages of a mixed cloud infrastructure comprising also spot instances. Although the latter type of instances are subject to failures and therefore provide an unreliable infrastructure, they potentially offer significant cost and time improvements if used wisely. This paper discusses a novel autoscaling strategy with two features. First, it combines both types of instances to acquire a better cost-performance balance in the infrastructure. And second, it uses heuristic scheduling to deal with the unreliability of spot instances. Simulated experiments based on 4 scientific workflows showed substantial makespan and cost reductions of our strategy when compared with a reference strategy from the state of the art entitled Scaling First. These promising results represent a step towards new and better strategies for workflow autoscaling in the cloud.
Guida-Johnson, B ;Faggi, AM ; Zuleta, GA ; RIVER RESEARCH AND APPLICATIONS ,2017 ,33 ,959 -969 .
Compact urbanization is the main strategy for sustainable urban development. However, it is yet unclear whether compact urban forms are ecologically more favourable than dispersed ones. In this paper, we studied the effects of urban sprawl on the riparian vegetation condition in one of the most degraded watersheds in the Buenos Aires metropolitan area, Argentina. We conducted random sampling of the riparian vegetation at sites along streams in the basin and assessed urban indicators at the reach and sub-watershed scales for each of those sites in a geographic information system: urban area, impervious surface, population density and two landscape metrics of dispersion. The indicators assessed explained a high proportion of the variability of the vegetation response variables, thereby confirming the importance of urban sprawl pressure in shaping riparian communities in fluvial ecosystems. Dispersed urbanization had more positive than negative effects on the vegetation in the study area. Riverbanks associated with dispersed urbanization had more plant species, including exotics, when urban sprawl was assessed at the local scale. At the sub-watershed scale, dispersed urbanized areas were richer in native plants and most of the functional groups, and poorer in exotic species. The model of the compact city, including bio-corridors along watercourses, has been proposed for the Buenos Aires conurbation process for the next decades. Our results showed that the quality of existing river corridors across the compact matrix was not desirable and best practices for redesigning a more sustainable landscape structure are necessary, including the restoration of habitats for wetland species. Copyright (c) 2017 John Wiley & Sons, Ltd.
Galassi, VV ;Del Popolo, MG ; Fischer, TM ; Wilke, N ; JOURNAL OF PHYSICAL CHEMISTRY B ,2017 ,121 ,5621 -5632 .
Langmuir monolayers of certain surfactants show a negative derivative of the surface pressure with respect to temperature. In these monolayers, a local temperature gradient leads to local yielding of the solid phase to a kinetically flowing liquid, so that the material flows toward the hotter regions that act as sinks. The accumulation of material leads to the formation of nonequilibrium multilamellar bubbles of different sizes, Here we investigate the molecular factors leading to such a peculiar behavior. First, we identify the required structural molecular moieties, and second we vary the composition of the subphase in order to analyze its influence. We conclude that esters appear to be unique in two key aspects: they form monolayers whose compression isotherms shift to lower areas as the temperature increases, and thus collapse into a hot spot; and they bind weakly to the aqueous subphase, i.e., water does not attach to the monolayer at the molecular level, but only supports it. Molecular simulations for a selected system confirm and help explain the observed behavior: surfactant molecules form a weak hydrogen bonding network, which is disrupted upon heating, and also the molecular tilting changes with temperature, leading to changes in the film density.
Barberena, R ;Mendez, C ; de Porras, ME ; JOURNAL OF ANTHROPOLOGICAL ARCHAEOLOGY ,2017 ,46 ,68 -81 .
Building on previous research at smaller scales, in this paper we assemble paleoecological data and archaeological time-series for deserts located in three latitudinal bands along the South American Arid Diagonal (16-41 S, 1,236,000 km(2) of area). Diverse proxies suggest the existence of arid and extremely arid conditions in large parts of these deserts. Working with a database composed of 914 archaeological dates falling between the first human presence in each region and 3000 years BP, which produce a minimum number of 578 occupational events, we identify a series of patterns at a macro-regional scale: a robust increase in the temporal signal at the beginning of the mid-Holocene (8000-7600 years BP) followed by two troughs (7600-7200, 6800-6400 years BP) during this period. The spatial scope of the data presented provides an opportunity for disentangling processes of spatial re-localization from actual changes in population size. We present a demographic hypothesis at a macro-regional scale, which suggests the existence of mid-Holocene population bottleneck(s). This hypothesis would account not only for the mid-Holocene troughs, but also for the posterior record of an intense and relatively rapid population growth (release) observed in many regions of the arid diagonal. These mid-Holocene events provide the context for independent trajectories of economic intensification based on different sets of resources marine foods, camelids, and also probably wetland resources-, some of which lead to domestication processes. These cases occur in association with a tendency towards reduced residential mobility in regions that may have acted as refugia during arid periods of the mid-Holocene.
Cabrillana, ME ;Monclus, MD ; Lancellotti, TES ; Boarelli, PV ; Vincenti, AE ; Fornes, MM ; Sanabria, EA ; Fornes, MW ; REPRODUCTION FERTILITY AND DEVELOPMENT ,2017 ,29 ,1435 -1446 .
Male infertility is a disorder of the reproductive system defined by the failure to achieve a clinical pregnancy after 12 months or more of regular unprotected sexual intercourse. The presence of low-motile or immotile spermatozoa is one of many causes of infertility; however, this observation provides little or no information regarding the pathogenesis of the malfunction. Good sperm motility depends on correct assembly of the sperm tail in the testis and efficient maturation during epididymal transit. Thiols of flagellar proteins, such as outer dense fibre protein 1 (ODF1), are oxidised to form disulfides during epididymal transit and the spermatozoa become motile. This study was designed to determine how oxidative changes in protein thiol status affect progressive motility in human spermatozoa. Monobromobimane (mBBr) was used as a specific thiol marker and disruptor of sperm progressive motility. When mBBr was blocked by dithiothreitol it did not promote motility changes. The analysis of mBBr-treated spermatozoa revealed a reduction of progressive motility and an increased number of spermatozoa with non-progressive motility without affecting ATP production. Laser confocal microscopy and western blot analysis showed that one of the mBBr-positive proteins reacted with an antibody to ODF1. Monobromobimane fluorescence intensity of the sperm tail was lower in normozoospermic than asthenozoospermic men, suggesting that thiol oxidation in spermatozoa of asthenozoospermic men is incomplete. Our findings indicate that mBBr affects the thiol status of ODF1 in human spermatozoa and interferes with progressive motility.
Barberena, R ;CURRENT ANTHROPOLOGY ,2017 ,58 ,398 -399 .
Barberena, R ;McDonald, J ; Mitchell, PJ ; Veth, P ; JOURNAL OF ANTHROPOLOGICAL ARCHAEOLOGY ,2017 ,46 ,1 -11 .
This introductory overview presents the frame of research and general goals of the special volume "Archaeological Discontinuities: Comparative Frameworks for the southern hemisphere". We begin by deconstructing archaeological discontinuities in terms of time and space in order to assess what sort of past phenomena are we dealing with when assessing discontinuities in different scales. It is one of our main contentions that we need theory and data connecting discontinuities as recorded on different analytical scales, thereby contributing to evaluate often-undescribed mechanisms that produce archaeological discontinuities. On this basis, we face the key task of deconstructing archaeological discontinuities from 'top to bottom', moving from the averaged material record that is visible in archaeological scale toward the short-term human decisions and interactions that, when occurring cumulatively, produce those discontinuities. Nevertheless, while an understanding of the short-term behavioral mechanisms and social agency behind discontinuities is necessary, it is certainly not sufficient for building a frame in which to make sense of the long-term record.
Fernandez, MV ;Barberena, R ; Rughini, AA ; Giesso, M ; Cortegoso, V ; Duran, V ; Villanueva, GR ; Borrazzo, K ; Lucero, G ; Garvey, R ; MacDonald, BL ; Glascock, MD ; JOURNAL OF ARCHAEOLOGICAL SCIENCE-REPORTS ,2017 ,13 ,372 -381 .
We studied the organization of mobility of hunter-gatherers groups of northwestern Patagonia (Argentina) from an interdisciplinary perspective. We combined geochemical and technological characterization of obsidian assemblages from surface and stratigraphic contexts spanning the Holocene, and a preliminary geoarchaeological study of the sources. The goals were to assess the provenance, mode of supply, use, and discard of obsidian artifacts on the basis of information on the structure of the two main regional sources: Cerro Huenul, located in the lowlands, and Laguna del Maule, located in the Andean highlands. We conducted geoarchaeological field sampling at different altitudes of the Barrancas River fluvial deposits to study the geomorphic impact on the secondary structure of the highland source. Preliminary geoarchaeological results allow extending the area of availability up to 90 km towards the lowlands from the outcrops. In addition, we performed non-destructive XRF analyses on 266 lithic artifacts, which were placed along a continuum of reduction. 89% of the artifacts corresponded to the local Cerro Huenul source, while 11% to Laguna del Maule. While the artifacts made on Cerro Huenul obsidian were represented by the full reduction sequence, those from Laguna del Maule are only represented by advanced stages. We integrate these results with information on the frequencies of projectile points, ceramics, and rock-art motifs for the two main archaeological sites in the region: Cueva Huenul 1 and Cueva Yagui. These proxies indicate that the sites have different place use histories, providing a scheme for the analysis of human use of the regional landscape.
Guida-Johnson, B ;Abraham, EM ; Cony, MA ; REVISTA DE LA FACULTAD DE CIENCIAS AGRARIAS ,2017 ,49 ,205 -215 .
Drylands are characterized among other things by low rainfall and soils with insufficient water. In these regions, agricultural production depends on irrigation, which transforms arid ecosystems into irrigated arableareas, as in the Cuyo region, in the central-western Argentina. Although these lands support the majority of the population, they are often associated with degradation processes. One of the main consequences of unsustainable agriculture is soil salinization, which occurs either because perennial deep-rooted native vegetation is replaced by annual crops or as a result of excessive irrigation and deficient drainage. Salinization is a global problem, since it reduces the productivity of large arable areas, decreases land value and leads to their abandonment. In this context, ecosystem restoration is a strategic approach to reverse the degradation of irrigated drylands, recover services and promote the conservation of arid ecosystems at the regional scale. In this paper we review the factors, both those linked to the biophysical environment and those determined by human activities, which are associated with salinization in different regions, as well as the implemented measures for rehabilitating these environments. Furthermore, the terminology associated with the practice of restoration is revised and a suitable alternative for exploring this approach in Cuyo is proposed: the productive restoration using species of the Prosopis genus.
Pol, RG ;Vargas, GA ; Marone, L ; ECOLOGICAL ENTOMOLOGY ,2017 ,42 ,283 -293 .
1. Human-induced rapid environmental change may decrease food resources and create unfavourable conditions for native species. Organisms showing a flexible foraging behaviour can exploit novel or alternative foods and are more likely to persist, whereas less flexible organisms might suffer starvation and numerical reductions. 2. This study assessed whether declines in the quality and availability of seeds prompted by grazing provoke behavioural and numerical responses in Pogonomyrmex mendozanus ants, and aimed to test whether behavioural flexibility buffers habitat degradation and prevents numerical declines. 3. Heavy grazing caused seed reductions, especially of the highly consumed and preferred grass seeds, and triggered two kinds of ant responses. Ants expanded their diet by incorporating a greater proportion of non-seed items, and they reduced foraging activity. As a consequence, the rate of food intake per colony lessened, particularly that of carbohydrate-rich seeds like grass seeds. Colony density under heavy grazing also fell. 4. Habitat degradation triggered a cascade of mechanisms that starts with a decrease in the seed resources and continues with changes in ant behaviour. However, behavioural responses were insufficient to prevent ant numerical declines. The results of this study suggest that the reduction in the colony density under habitat degradation was provoked by ant nutritional deficit and starvation, and predict a deterioration in body condition, colony performance and reproduction of ants, which deserve further assessment.
Bilen, AM ;Kaluza, P ; EUROPEAN PHYSICAL JOURNAL B ,2017 ,90 ,-.
We present a discrete-time formulation for the autonomous learning conjecture. The main feature of this formulation is the possibility to apply the autonomous learning scheme to systems in which the errors with respect to target functions are not well-defined for all times. This restriction for the evaluation of functionality is a typical feature in systems that need a finite time interval to process a unit piece of information. We illustrate its application on an artificial neural network with feed-forward architecture for classification and a phase oscillator system with synchronization properties. The main characteristics of the discrete-time formulation are shown by constructing these systems with predefined functions.
Ridano, ME ;Subirada, PV ; Paz, MC ; Lorenc, VE ; Stupirski, JC ; Gramajo, AL ; Luna, JD ; Croci, DO ; Rabinovich, GA ; Sanchez, MC ; ONCOTARGET ,2017 ,8 ,32505 -32522 .
Neovascular retinopathies are leading causes of irreversible blindness. Although vascular endothelial growth factor (VEGF) inhibitors have been established as the mainstay of current treatment, clinical management of these diseases is still limited. As retinal impairment involves abnormal neovascularization and neuronal degeneration, we evaluated here the involvement of galectin-1 in vascular and non-vascular alterations associated with retinopathies, using the oxygen-induced retinopathy (OIR) model. Postnatal day 17 OIR mouse retinas showed the highest neovascular profile and exhibited neuro-glial injury as well as retinal functional loss, which persisted until P26 OIR. Concomitant to VEGF up-regulation, galectin-1 was highly expressed in P17 OIR retinas and it was mainly localized in neovascular tufts. In addition, OIR induced remodelling of cell surface glycophenotype leading to exposure of galectin-1-specific glycan epitopes. Whereas VEGF returned to baseline levels at P26, increased galectin-1 expression persisted until this time period. Remarkably, although anti-VEGF treatment in P17 OIR improved retinal vascularization,neithergalectin-1 expression nor non-vascular and functional alterations were attenuated. However, this functional defect was partially prevented in galectin-1-deficient (Lgals1(-/-)) OIR mice, suggesting the importance of targeting both VEGF and galectin-1 as non-redundant independent pathways. Supporting the clinical relevance of these findings, we found increased levels of galectin-1 in aqueous humor from patients with proliferative diabetic retinopathy and neovascular glaucoma. Thus, using an OIR model and human samples, we identified a role for galectin-1 accompanying vascular and non-vascular retinal alterations in neovascular retinopathies.
Kaluza, P ;EUROPEAN PHYSICAL JOURNAL B ,2017 ,90 ,-.
We present a study about the construction of functional flow processing networks that produce prescribed output patterns (target functions). The constructions are performed with a process of mutations and selections by an annealing-like algorithm. We consider the coevolution of the prescribed target functions during the optimization processes. We propose three different paths for these coevolutions in order to evolve from a simple initial function to a more complex final one. We compute several network properties during the optimizations by using the different path-coevolutions as mean values over network ensembles. As a function of the number of iterations of the optimization we find a similar behavior like a phase transition in the network structures. This result can be seen clearly in the mean motif distributions of the constructed networks. Coevolution allows to identify that feed-forward loops are responsible for the development of the temporal response of these systems. Finally, we observe that with a large number of iterations the optimized networks present similar properties despite the path-coevolution we employed.
Suarez, DS ;Pinna, EG ; Rosales, GD ; Rodriguez, MH ; MINERALS ,2017 ,7 ,-.
Lithium (Li) is considered a strategic element whose use has significantly expanded. Its current high demand is due to its use in lithium ion batteries for portable electronic devices, whose manufacture and market are extensively growing every day. These days there is a great concern about the final disposal of these batteries. Therefore, the possibility of developing new methodologies to recycle their components is of great importance, both commercially and environmentally. This paper presents results regarding important operational variables for the dissolution of the lithium and cobalt mixed-oxide (LiCoO2) cathodes from spent lithium ion batteries (LIBs) with hydrofluoric acid. The recovery and synthesis of Co and Li compounds were also investigated. The dissolution parameters studied were: temperature, reaction time, solid-liquid ratio, stirring speed, and concentration of HF. The investigated recovery parameters included: pH, temperature, and time with and without stirring. The final precipitation of lithium fluoride was also examined. The results indicate that an increase in the HF concentration, temperature, and reaction time favors the leaching reaction of the LiCoO2. Dissolutions were close to 60%, at 75 degrees C and 120 min with a HF concentration of 25% (v/v). The recovery of Co and Li were 98% and 80%, respectively, with purities higher than 94%. Co and Li compounds, such as Co3O4 and LiF, were synthesized. Furthermore, it was possible to almost completely eliminate the F- ions as CaF2.
Millan, EN ;Goiran, S ; Aranibar, JN ; Bringa, EM ; ECOLOGICAL INFORMATICS ,2017 ,39 ,84 -98 .
Human settlements in arid environments are becoming widespread due to population growth, and without planning, they may alter vegetation and ecosystem processes, compromising sustainability. We hypothesize that in an arid region of the central Monte desert (Mendoza, Argentina), surface and groundwater availability are the primary factors controlling livestock settlements establishment and success as productive units, which affect patterns of degradation in the landscape. To evaluate this hypothesis we simulated settlement dynamics using a Monte Carlo based model of Settlement Dynamics in Drylands (SeDD), which calculates probabilities on a gridded region based on six environmental factors: groundwater depth, vegetation type, proximity to rivers, paved road, old river beds, and existing settlements. A parameter sweep, including millions of simulations, was run to identify the most relevant factors controlling settlements. Results indicate that distances to rivers and the presence of old river beds are critical to explain the current distribution of settlements, while vegetation, paved roads, and water table depth were not as relevant to explain settlement distribution. Far from surface water sources, most settlements were established at random, suggesting that pressures to settle in unfavorable places control settlement dynamics in those isolated areas. The simulated vegetation, which considers degradation around livestock settlements, generally matched the spatial distribution of remotely sensed vegetation classes, although with a higher cover of extreme vegetation classes. The model could be a useful tool to evaluate effects of land use changes, such as water provision or changes on river flows, on settlement distribution and vegetation degradation in arid environments. (C) 2017 Elsevier B.V. All rights reserved.
Mammana, SB ;Berton, P ; Camargo, AB ; Lascalea, GE ; Altamirano, JC ; ELECTROPHORESIS ,2017 ,38 ,1334 -1343 .
An analytical methodology based on coprecipitation-assisted coacervative extraction coupled to HPLC-UV was developed for determination of five organophosphorus pesticides (OPPs), including fenitrothion, guthion, parathion, methidathion, and chlorpyrifos, in water samples. It involves a green technique leading to an efficient and simple analytical methodology suitable for high-throughput analysis. Relevant physicochemical variables were studied and optimized on the analytical response of each OPP. Under optimized conditions, the resulting methodology was as follows: an aliquot of 9 mL of water sample was placed into a centrifuge tube and 0.5 mL sodium citrate 0.1 M, pH 4; 0.08 mL Al-2(SO4)(3) 0.1 M; and 0.7 mL SDS 0.1 M were added and homogenized. After centrifugation the supernatant was discarded. A 700 L aliquot of the coacervate-rich phase obtained was dissolved with 300 L of methanol and 20 L of the resulting solution was analyzed by HPLC-UV. The resulting LODs ranged within 0.7-2.5 ng/mL and the achieved RSD and recovery values were <8% (n = 3) and >81%, respectively. The proposed analytical methodology was successfully applied for the analysis of five OPPs in water samples for human consumption of different locations of Mendoza.
Dellagnola, FA ;Vega, IA ; Castro-Vazquez, A ; JOURNAL OF MOLLUSCAN STUDIES ,2017 ,83 ,186 -193 .
Two types of pigmented intracellular bodies have been reported in the digestive glands of several caenogastropods, particularly in the families Ampullariidae (Architaenioglossa: Ampullarioidea), Strombidae and Struthiolariidae (Littorinimorpha: Stromboidea). Rounded corpuscles, which are usually light brown, are identified here as C corpuscles, while corpuscles that are oval, darker and larger are identified as K corpuscles. We studied both corpuscular types in Lobatus gigas (Strombidae) using (1) differential-interference contrast microscopy, (2) transmission electron microscopy, (3) in situ hybridization with a generalized cyanobacterial 16S rRNA probe and (4) autofluorescence before and after lysozyme digestion. Results indicated that C corpuscles were located in the basal regions of columnar cells and the intensity of their pigmentation and alcianophily (indicative of glycosaminoglycans) was variable. They showed an electron-dense wall and contained abundant electron-dense clumps and irregularly arranged membranes, but no thylakoids or nuclei. Hybridization with the 16S rRNA probe varied from none to intense in C corpuscles, indicative of variations in the rRNA content during their life cycles. Their walls were sensitive to lysozyme digestion, which strongly suggests that peptidoglycans are an integral part of this structure. K corpuscles were located within pyramidal cells and were uniformly dark brown but variably alcianophilic. They showed multiple lamellae of moderate electron density, organized around one to three cores, each one containing one or several small spherical bodies. All K corpuscles hybridized with the 16S rRNA probe and were partly digested by lysozyme. Both C and K corpuscles showed red autofluorescence, which suggests the presence of chlorophyll-like pigments. It is concluded that C and K corpuscles in the digestive gland of L. gigas may be forms of a prokaryotic symbiont related to the Cyanobacteria.
Pena-Rodriguez, O ;Prada, A ; Olivares, J ; Oliver, A ; Rodriguez-Fernandez, L ; Silva-Pereyra, HG ; Bringa, E ; Perlado, JM ; Rivera, A ; SCIENTIFIC REPORTS ,2017 ,7 ,-.
In this work we have studied the elongation of silver nanoparticles irradiated with 40 MeV Bromine ions by means of in situ optical measurements, transmission electron microscopy and molecular dynamics simulations. The localized surface plasmon resonance of silver nanoparticles has a strong dependence on the particle shape and size, which allowed us to obtain the geometrical parameters with remarkable accuracy by means of a fit of the optical spectra. Optical results have been compared with transmission electron microscopy images and molecular dynamics simulations and the agreement is excellent in both cases. An important advantage of in situ measurements is that they yield an extremely detailed information of the full elongation kinetics. Final nanoparticle elongation depends on a complex competition between single-ion deformation, Ostwald ripening and dissolution. Building and validating theoretical models with the data reported in this work should be easier than with the information previously available, due to the unprecedented level of kinetic details obtained from the in situ measurements.
Masone, D ;Uhart, M ; Bustos, DM ; SCIENTIFIC REPORTS ,2017 ,7 ,-.
Twenty years ago, a novel concept in protein structural biology was discovered: the intrinsically disordered regions (IDRs). These regions remain largely unstructured under native conditions and the more are studied, more properties are attributed to them. Possibly, one of the most important is their ability to conform a new type of protein-protein interaction. Besides the classical domain-todomain interactions, IDRs follow a 'fly-casting' model including 'induced folding'. Unfortunately, it is only possible to experimentally explore initial and final states. However, the complete movie of conformational changes of protein regions and their characterization can be addressed by in silico experiments. Here, we simulate the binding of two proteins to describe how the phosphorylation of a single residue modulates the entire process. 14-3-3 protein family is considered a master regulator of phosphorylated proteins and from a modern point-of-view, protein phosphorylation is a three component system, with writers (kinases), erasers (phosphatases) and readers. This later biological role is attributed to the 14-3-3 protein family. Our molecular dynamics results show that phosphorylation of the key residue Thr31 in a partner of 14-3-3, the aralkylamine N-acetyltransferase, releases the flycasting mechanism during binding. On the other hand, the non-phosphorylation of the same residue traps the proteins, systematically and repeatedly driving the simulations into wrong protein-protein conformations.
Crespo, S ;Aranibar, J ; Gomez, L ; Schwikowski, M ; Bruetsch, S ; Cara, L ; Villalba, R ; HYDROLOGICAL SCIENCES JOURNAL-JOURNAL DES SCIENCES HYDROLOGIQUES ,2017 ,62 ,588 -605 .
The Mendoza River is mainly dependent on the melting of snow and ice in the Upper Andes. Since predicted changes in climate would modify snow accumulation and glacial melting, it is important to understand the relative contributions of various water sources to river discharge. The two main mountain ranges in the basin, Cordillera Principal and Cordillera Frontal, present differences in geology and receive differing proportions of precipitation from Atlantic and Pacific moisture sources. We propose that differences in the origin of precipitation, geology and sediment contact times across the basin generate ionic and stable isotopic signatures in the water, allowing the differentiation of water sources. Waters from the Cordillera Principal had higher salinity and were more isotopically depleted than those from the Cordillera Frontal. Stable isotope composition and salinity differed among different water sources. The chemical temporal evolution of rivers and streams indicated changes in the relative contributions of different sources, pointing to the importance of glacier melting and groundwater in the river discharge.
Sanchez-Puerta, MV ;Garcia, LE ; Wohlfeiler, J ; Ceriotti, LF ; NEW PHYTOLOGIST ,2017 ,214 ,376 -387 .
Horizontal gene transfer (HGT) among flowering plant mitochondria occurs frequently and, in most cases, leads to nonfunctional transgenes in the recipient genome. Parasitic plants are particularly prone to this phenomenon, but their mitochondrial genomes (mtDNA) have been largely unexplored.
Cerliani, JP ;Blidner, AG ; Toscano, MA ; Croci, DO ; Rabinovich, GA ; TRENDS IN BIOCHEMICAL SCIENCES ,2017 ,42 ,255 -273 .
The vast range and complexity of glycan structures and their dynamic variations in health and disease have presented formidable challenges toward understanding the biological significance of these molecules. Despite these limitations, compelling evidence highlights a major role for galectins, a family of soluble glycan-binding proteins, as endogenous decoders that translate glycan-containing information into a broad spectrum of cellular responses by modulating receptor clustering, reorganization, endocytosis, and signaling. Here, we underscore pioneer findings and recent advances in understanding the biology of galectin-glycan interactions in myeloid, lymphoid, and endothelial compartments, highlighting important pathways by which these multivalent complexes control immune and vascular programs. Implementation of novel glycoanalytical approaches, as well as the use of genetically engineered cell and organism models, have allowed glycans and galectins to be explored across a range of cellular processes.
Locatelli, DA ;Nazareno, MA ; Fusari, CM ; Camargo, AB ; FOOD CHEMISTRY ,2017 ,220 ,219 -224 .
The antioxidant properties and the main beneficial organosulphur compounds of home-cooked garlic samples were studied in order to establish relationships between them. Antioxidant activity was tested by free radical scavenging against 2,2-diphenyl-1-picrylhydrazyl radical (DPPH center dot) and 2,2'-azino-bis(3-ethylbenzo-thiazoline-6-sulfonic acid) diammonium salt (ABTS(+center dot)), Fe(III) reducing ability (FRAP) and linoleic acid co-oxidation initiated by soybean lipoxygenase in a micelle system. DPPH, ABTS and FRAP assays showed the highest activity for raw garlic samples, while beta-carotene bleaching assay yielded the highest activity for stir-fried garlic. Pure organosulphur compounds tested by DPPH, FRAP and beta-carotene bleaching assays showed that allicin had an antiradical action mechanism, as well as iron reducing capacity; while antioxidant activity was the main mechanism for ajoenes and 2-VD. To our knowledge, this study is the first demonstration that home-cooked garlic retains its antioxidant activity, and, at the same time, elucidates the mechanisms involved in this activity. (C) 2016 Elsevier Ltd. All rights reserved.
Grijalba, AC ;Fiorentini, EF ; Wuilloud, RG ; JOURNAL OF CHROMATOGRAPHY A ,2017 ,1491 ,117 -125 .
Different ionic liquids (ILs) were assayed as mobile phase modifiers for the separation and determination of selenite [Se(IV)1, selenate [Se(VI)], selenomethionine (SeMet) and Se-methylselenocysteine (SeMeSeCys) by reversed-phase high-performance liquid chromatography coupled to hydride generation atomic fluorescence spectrometry (RP-HPLC-HG-AFS). The use of several ILs: 1-butyl-3-methylimidazolium chloride, 1-hexyl-3-methylimidazolium chloride ([C(6)mirn]Cl), 1-octy1-3-methylimidazolium chloride, 1-dodecyl-3-methylimidazolium bromide, 1-hexadecy1-3-methylimidazolium bromide and tributyl(methyl)phosphonium methylsulphate was evaluated. Also, the effect of pH, buffer type and IL concentration on the separation of Se species was studied. Complete separation was attained within 12 min using a C-8 column and a gradient performed with a mobile phase containing 0.1% (v/v) [C(6)mim]Cl at pH 6.0. The proposed method allows the separation of inorganic and organic Se species in a single chromatographic run, adding further benefits over already reported methods based on RP-HPLC. In addition, the influence of ILs on the AFS signals of each Se species was evaluated and a multivariate methodology was used for optimization of AFS sensitivity. The limits of detection were 0.92, 0.86,1.41 and 1.19 mu gL(-1) for Se(IV), Se(VI), SeMet and SeMeSeCys, respectively. The method was successfully applied for speciation analysis of Se in complex samples, such as wine, beer, yeast and garlic. (C) 2017 Elsevier B.V. All rights reserved.
Grijalba, AC ;Martinis, EM ; Wuilloud, RG ; FOOD CHEMISTRY ,2017 ,219 ,102 -108 .
A highly sensitive vortex assisted liquid-liquid microextraction (VA-LLME) method was developed for inorganic Se [Se(IV) and Se(VI)] speciation analysis in Allium and Brassica vegetables. Trihexyl(tetrade cyl)phosphonium decanoate phosphonium ionic liquid (IL) was applied for the extraction of Se(IV)ammonium pyrrolidine dithiocarbamate (APDC) complex followed by Se determination with electrothermal atomic absorption spectrometry. A complete optimization of the graphite furnace temperature program was developed for accurate determination of Se in the IL-enriched extracts and multivariate statistical optimization was performed to define the conditions for the highest extraction efficiency. Significant factors of IL-VA-LLME method were sample volume, extraction pH, extraction time and APDC concentration. High extraction efficiency (90%), a 100-fold preconcentration factor and a detection limit of 5.0 ng/L were achieved. The high sensitivity obtained with preconcentration and the non-chromatographic separation of inorganic Se species in complex matrix samples such as garlic, onion, leek, broccoli and cauliflower, are the main advantages of IL-VA-LLME. (C) 2016 Elsevier Ltd. All rights reserved.
Fosco, CD ;Remaggi, ML ; EUROPEAN PHYSICAL JOURNAL C ,2017 ,77 ,-.
We study the Casimir interaction energy due to the vacuum fluctuations of the electromagnetic (EM) field in the presence of two mirrors, described by 2 + 1-dimensional, generally nonlocal actions, which may contain both parity-conserving and parity-breaking terms. We compare the results with the ones corresponding to Chern-Simons boundary conditions and evaluate the interaction energy for several particular situations.
Gandini, CL ;Sanchez-Puerta, MV ; SCIENTIFIC REPORTS ,2017 ,7 ,-.
Angiosperm mitochondrial genomes (mtDNA) exhibit variable quantities of alien sequences. Many of these sequences are acquired by intracellular gene transfer (IGT) from the plastid. In addition, frequent events of horizontal gene transfer (HGT) between mitochondria of different species also contribute to their expanded genomes. In contrast, alien sequences are rarely found in plastid genomes. Most of the plant-to-plant HGT events involve mitochondrion-to-mitochondrion transfers. Occasionally, foreign sequences in mtDNAs are plastid-derived (MTPT), raising questions about their origin, frequency, and mechanism of transfer. The rising number of complete mtDNAs allowed us to address these questions. We identified 15 new foreign MTPTs, increasing significantly the number of those previously reported. One out of five of the angiosperm species analyzed contained at least one foreign MTPT, suggesting a remarkable frequency of HGT among plants. By analyzing the flanking regions of the foreign MTPTs, we found strong evidence for mt-to-mt transfers in 65% of the cases. We hypothesize that plastid sequences were initially acquired by the native mtDNA via IGT and then transferred to a distantly-related plant via mitochondrial HGT, rather than directly from a foreign plastid to the mitochondrial genome. Finally, we describe three novel putative cases of mitochondrial-derived sequences among angiosperm plastomes.
Rosales, GD ;Pinna, EG ; Suarez, DS ; Rodriguez, MH ; MINERALS ,2017 ,7 ,-.
This work describes the development of a new process for the recovery of Li, Al and Si along with the proposal of a flow sheet for the precipitation of those metals. The developed process is comprised of lepidolite acid digestion with hydrofluoric acid, and the subsequent precipitation of the metals present in the leach liquor. The leaching operational parameters studied were: reaction time, temperature and HF concentration. The experimental results indicate that the optimal conditions to achieve a Li extraction higher than 90% were: solid-liquid ratio, 1.82% (w/v); temperature, 123 degrees C; HF concentration, 7% (v/v); stirring speed, 330 rpm; and reaction time, 120 min. Al and Si can be recovered as Na3AlF6 and K2SiF6. LiF was separated from the leach liquor during water evaporation, with recovery values of 92%.
Gutierres, LI ;Lima, NW ; Thomaz, RS ; Papaleo, RM ; Bringa, EM ; COMPUTATIONAL MATERIALS SCIENCE ,2017 ,129 ,98 -106 .
Impacts of swift heavy ions of different energy loss in amorphous and crystalline Lennard-Jones (L.) thin films (2-60 nm) were simulated using classical molecular dynamics to study cratering and sputtering in model molecular thin films. Crater size is determined mostly by evaporation and melt flow from the hot ion track, while rim size is determined both by melt flow and by coherent displacement of particles due to the large pressure developed in the excited region, with minor influence of particles from the substrate. Sputtering yields from both crystalline and amorphous samples are similar (including the scaling with energy loss), due to the extremely high temperature and disordered condition of the track region from where most ejected particles originate in the early stages of the track evolution. Cratering, however clearly depends on the crystallinity of the film. Craters and rims are much smaller in crystalline films mainly due to faster energy dissipation, higher stress threshold for plasticity and smaller free-volume in the ordered phase. We also found a large dependence of the induced surface effects on film thickness below a critical thickness value. The pressure pulse due to the ion impact is weaker and cooling of the excited track is more efficient in short tracks, both contributing to the decreased radiation damage efficiency on ultrathin layers. Despite the simplicity of the LJ model, the simulations in the amorphous films reproduce remarkably well several of the experimental features seen recently on polymer thin and ultra thin films irradiated by swift heavy ions. (C) 2016 Elsevier B.V. All rights reserved.
Marrero, HJ ;Torretta, JP ; Vazquez, DP ; Hodara, K ; Medan, D ; AGRICULTURE ECOSYSTEMS & ENVIRONMENT ,2017 ,239 ,304 -309 .
Agricultural land management modifies ecosystem structure and functioning in natural landscapes. Pollinators are a key functional group that may suffer from such intensification. Here we evaluate how agricultural land management influences the diversity of pollen transported by pollinators and the pollination niche overlap among plants. We described pollen transport networks (which allow assessing the contribution of pollinators to the flow of pollen among plants) in agricultural and restored fragments in three sites representative of the pampas region of Argentina. We analyzed diversity of pollen transported by pollinators and the pollination niche overlap among plants in both types of fragments with general and generalized linear mixed models. The agricultural fragments were associated to increased diversity of transported pollen and pollination niche overlap among plants. Greater pollination niche overlap in agricultural fragments was associated with increased abundance of exotic plants. Our results indicate that agricultural intensification has significantly increased the diversity of pollen and the pollination niche overlap in natural communities by promoting exotic plants and generalized plant pollinator interactions. Strategies to encourage improvements in the quality of pollination in agroecosystems could range from controlling the levels of exotic species to mechanisms that promote increased diversity of native plants. (C) 2017 Elsevier B.V. All rights reserved.
Martinez-Asencio, J ;Ruestes, CJ ; Bringa, E ; Caturla, MJ ; NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM ,2017 ,393 ,44 -48 .
Irradiation with low energy Ar ions of graphene membranes gives rise to changes in the mechanical properties of this material. These changes have been associated to the production of defects, mostly isolated vacancies. However, the initial state of the graphene membrane can also affect its mechanical response. Using molecular dynamics simulations we have studied defect production in graphene membranes irradiated with 140 eV Ar ions up to a dose of 0.075 x 10(14) ions/cm(2) and different initial strains, from 0.25% (compressive strain) to 0.25% (tensile strain). For all strains, the number of defects increases linearly with dose with a defect production of about 80% (80 defects every 100 ions). Defects are mostly single vacancies and di-vacancies, although some higher order clusters are also observed. Two different types of di-vacancies have been identified, the most common one being two vacancies at first nearest neighbours distance. Differences in the total number of defects with the applied strain are observed which is related to the production of a higher number of di-vacancies under compressive strain compared to tensile strain. We attribute this effect to the larger out-of-plane deformations of compressed samples that could favor the production of defects in closer proximity to others. (C) 2016 Elsevier B.V. All rights reserved.
Pennacchio, GE ;Neira, FJ ; Soaje, M ; Jahn, GA ; Valdez, SR ; MOLECULAR AND CELLULAR ENDOCRINOLOGY ,2017 ,442 ,40 -50 .
Hyperthyroidism (HyperT) compromises pregnancy and lactation, hindering suckling-induced PRL release. We studied the effect of HyperT on hypothalamic mRNA (RT-qPCR) and protein (Western blot) expression of tyrosine hydroxylase (TH), PRL receptor (PRLR) and signaling pathway members, estrogen-alpha (ER alpha) and progesterone (PR) receptors on late pregnancy (days G19, 20 and 21) and early lactation (L2) in rats. HyperT advanced pre-partum PRL release, reduced circulating PRL on L2 and increased TH mRNA (G21 and L2), p-TH, PRLR mRNA, STAT5 protein (G19 and L2), PRLR protein (G21) and CIS protein (G19). PRs mRNAs and protein decreased on G19 but afterwards PRA mRNA (G20), PRB mRNA (G21) and PRA mRNA and protein (L2) increased. ER alpha protein increased on G19 and decreased on G20. Thus, the altered hypothalamic PRLR, STAT5, PR and ER alpha expression in hyperthyroid rats may induce elevated TH expression and activation, that consequently, elevate dopaminergic tone during lactation, blunting suckling-induced PRL release and litter growth. (C) 2016 Elsevier Ireland Ltd. All rights reserved.
Cianci, N ;Ottina, M ; TOPOLOGY AND ITS APPLICATIONS ,2017 ,217 ,1 -19 .
We develop a new method to compute the homology groups of Alexandroff topological spaces (or equivalently of partially ordered sets) by means of spectral sequences giving a complete and simple description of the corresponding differentials. Applying our tools, we obtain a generalization of a result of Minian in homological Morse theory for posets. (C) 2016 Elsevier B.V. All rights reserved.
Fernandez, RP ;Kinnison, DE ; Lamarque, JF ; Tilmes, S ; Saiz-Lopez, A ; ATMOSPHERIC CHEMISTRY AND PHYSICS ,2017 ,17 ,1673 -1688 .
Active bromine released from the photochemical decomposition of biogenic very short-lived bromocarbons (VSLBr) enhances stratospheric ozone depletion. Based on a dual set of 1960-2100 coupled chemistry-climate simulations (i.e. with and without VSLBr), we show that the maximum Antarctic ozone hole depletion increases by up to 14% when natural VSLBr are considered, which is in better agreement with ozone observations. The impact of the additional 5 pptv VSLBr on Antarctic ozone is most evident in the periphery of the ozone hole, producing an expansion of the ozone hole area of similar to 5 million km(2), which is equivalent in magnitude to the recently estimated Antarctic ozone healing due to the implementation of the Montreal Protocol. We find that the inclusion of VSLBr in CAM-Chem (Community Atmosphere Model with Chemistry, version 4.0) does not introduce a significant delay of the modelled ozone return date to 1980 October levels, but instead affects the depth and duration of the simulated ozone hole. Our analysis further shows that total bromine-catalysed ozone destruction in the lower stratosphere surpasses that of chlorine by the year 2070 and indicates that natural VSLBr chemistry would dominate Antarctic ozone seasonality before the end of the 21st century. This work suggests a large influence of biogenic bromine on the future Antarctic ozone layer.
Marsh, EJ ;Kidd, R ; Ogburn, D ; Duran, V ; RADIOCARBON ,2017 ,59 ,117 -140 .
The chronology of the Inca Empire has traditionally relied on ethnohistoric dates, which suggest that a northern expansion into modern Ecuador began in AD 1463 and a southern expansion into modern Argentina began in AD 1471. We test the validity of these dates with two Bayesian models, which show that the ethnohistoric dates are incorrect and that the southern expansion began before the northern one. The first model of seven dates shows that the site of Chamical, Ecuador, was first occupied cal AD 1410-1480 (95% probability) and has a high probability of being built prior to the ethnohistoric date. The second is an outlier model of 26 C-14 dates and 19 thermoluminescence (TL) dates from 10 sites along the empire's southeastern limit in northwestern Mendoza, Argentina. Here, the Inca occupation began cal AD 1350-1440 (95% probability), also earlier than the ethnohistoric date. The model also suggests that the Inca occupation of Mendoza lasted 70-230 yr (95% probability), longer than previously thought, which calls for new perspectives on the timing and nature of Inca conquests and relationships with local groups. Based on these results, we argue it is time to abandon the traditional chronology in favor of Inca chronologies based on Bayesian models.
Moyano, LG ;EUROPEAN PHYSICAL JOURNAL-SPECIAL TOPICS ,2017 ,226 ,499 -518 .
In this review I present several representation learning methods, and discuss the latest advancements with emphasis in applications to network science. Representation learning is a set of techniques that has the goal of efficiently mapping data structures into convenient latent spaces. Either for dimensionality reduction or for gaining semantic content, this type of feature embeddings has demonstrated to be useful, for example, for node classification or link prediction tasks, among many other relevant applications to networks. I provide a description of the state-of-the-art of network representation learning as well as a detailed account of the connections with other fields of study such as continuous word embeddings and deep learning architectures. Finally, I provide a broad view of several applications of these techniques to networks in various domains.
Mazzolari, AC ;Marrero, HJ ; Vazquez, DP ; BIOLOGICAL INVASIONS ,2017 ,19 ,615 -623 .
The type of reproductive system may be an important trait for the establishment and maintenance of populations of invasive plant species in new areas, as it can influence their demography and genetics. We studied the breeding system of two exotic invasive species, Rosa rubiginosa and R. canina, in a natural reserve in Argentina, using a combination of pollination experiments. We asked how the different reproductive modes of these species affect the quantity and quality of the fruits and seed produced. Our results show that both invasive rose species have an array of reproductive strategies, and that they are able to invade without pollinators, as they can produce seeds in the same quantity and quality through wind-pollination, self-pollination, and apomixis. Such lack of dependence on pollinators and pollination for reproduction should enhance colonization into new areas, suggesting the need of intensive monitoring of spread and dispersal. Considering that both species are successful invaders in the region, our results are in line with Baker's rule, which posits that plants capable of uniparental reproduction are more likely to invade new areas.
Vitale, N ;Vazquez, DP ; APIDOLOGIE ,2017 ,48 ,31 -40 .
Studying bee nests can enlighten our understanding of feeding specialization and phylogenetic relationships of bees. We studied the nesting and feeding habits of Trichothurgus laticeps in the Monte desert ecosystem. Our results show that T. laticeps is attracted to pre-existing cavities in wood (trap nests), which were further excavated for nest construction; nest cells are unlined and provisioned almost exclusively with pollen of the cactus Opuntia sulphurea. The species overwinters inside a hard cocoon. Our results reinforce the hypothesis previously proposed by other authors that the unworked pollen mass and oligolecty are plesiomorphic characters in the Megachilidae, and that the wood-boring behavior for nest construction indicates convergent evolution with the Xylocopinae. We also propose that the cocoon structure might represent an evolutionary novelty for the Lithurginae.
Vazquez, DP ;Gianoli, E ; Morris, WF ; Bozinovic, F ; BIOLOGICAL REVIEWS ,2017 ,92 ,22 -42 .
While average temperature is likely to increase in most locations on Earth, many places will simultaneously experience higher variability in temperature, precipitation, and other climate variables. Although ecologists and evolutionary biologists widely recognize the potential impacts of changes in average climatic conditions, relatively little attention has been paid to the potential impacts of changes in climatic variability and extremes. We review the evidence on the impacts of increased climatic variability and extremes on physiological, ecological and evolutionary processes at multiple levels of biological organization, from individuals to populations and communities. Our review indicates that climatic variability can have profound influences on biological processes at multiple scales of organization. Responses to increased climatic variability and extremes are likely to be complex and cannot always be generalized, although our conceptual and methodological toolboxes allow us to make informed predictions about the likely consequences of such climatic changes. We conclude that climatic variability represents an important component of climate that deserves further attention.
Meglioli, PA ;Aranibar, JN ; Villagra, PE ; Riveros, CV ; CATENA ,2017 ,149 ,86 -97 .
Changes in the spatial distribution of resources constitute an indicator of degradation of arid grazing lands. In arid and semi-arid ecosystems, the distribution of soil resources has been commonly associated with the structure and the spatial arrangements of the vegetation. Although the formation of "fertile islands" beneath vegetation patches is well documented, much less is known about the changes induced by grazing systems on the distribution of soil resources. We examine how pastoralist settlements are affecting the spatial distribution of soil resources and the soil nutrient balance in central-western woodlands of Argentina. We analyzed the distribution of soil water, chloride, nitrate, total nitrogen, and organic matter at increasing distances from livestock corrals and in undisturbed woodlands, at different soil depths. We also calculated variation indexes of soil organic matter and total nitrogen produced by livestock settlements, as an indicator of degree of deterioration or improvement of the soils. The transects located in pastoralist settlements demonstrated an increasing centripetal gradient in availability of soil water and nutrients compared to transects outside of these disturbed areas. Livestock corrals create local hotspots of nutrient enrichment, but when we analyzed the effects of livestock settlements at a higher spatial scale, we found net losses of soil organic matter and total nitrogen. We conclude that the coupling between nutrient and patch dynamics is disrupted by the pastoralist settlements, which caused a redistribution of soil resources, controlled by the location from the livestock corrals. The processes that promote nutrient losses, such as ammonium volatilization, denitrification, nitrate leaching, organic matter oxidation, manure exports, and soil erosion, are relatively higher than the extra inputs of dung and urine. Therefore, this study emphasizes the role of grazing systems as modulators of water and nutrient fluxes, and soil nutrient balance. (C) 2016 Elsevier B.V. All rights reserved.
Moguilner, S ;Garcia, AM ; Mikulan, E ; Garcia, MD ; Vaucheret, E ; Amarillo, Y ; Bekinschtein, TA ; Ibanez, A ; NEUROSCIENCE OF CONSCIOUSNESS ,2017 ,3 ,-.
Consciousness impairments have been described as a cornerstone of epilepsy. Generalized seizures are usually characterized by a complete loss of consciousness, whereas focal seizures have more variable degrees of responsiveness. In addition to these impairments that occur during ictal episodes, alterations of consciousness have also been repeatedly observed between seizures (i.e. during interictal periods). In this opinion article, we review evidence supporting the novel hypothesis that epilepsy produces consciousness impairments which remain present interictally. Then, we discuss therapies aimed to reduce seizure frequency, which may modulate consciousness between epileptic seizures. We conclude with a consideration of relevant path-ophysiological mechanisms. In particular, the thalamocortical network seems to be involved in both seizure generation and interictal consciousness impairments, which could inaugurate a promising translational agenda for epilepsy studies.
Delgui, LR ;Colombo, MI ; FRONTIERS IN CELLULAR AND INFECTION MICROBIOLOGY ,2017 ,7 ,-.
Viruses are lifeless particles designed for setting virus-host interactome assuring a new generation of virions for dissemination. This interactome generates a pressure on host organisms evolving mechanisms to neutralize viral infection, which places the pressure back onto virus, a process known as virus-host cell co-evolution. Positive-single stranded RNA (+sRNA) viruses are an important group of viral agents illustrating this interesting phenomenon. During replication, their genomic +sRNA is employed as template for translation of viral proteins; among them the RNA-dependent RNA polymerase (RdRp) is responsible of viral genome replication originating double-strand RNA molecules (dsRNA) as intermediates, which accumulate representing a potent threat for cellular dsRNA receptors to initiate an antiviral response. A common feature shared by these viruses is their ability to rearrange cellular membranes to serve as platforms for genome replication and assembly of new virions, supporting replication efficiency increase by concentrating critical factors and protecting the viral genome from host anti-viral systems. This review summarizes current knowledge regarding cellular dsRNA receptors and describes prototype viruses developing replication niches inside rearranged membranes. However, for several viral agents it's been observed both, a complex rearrangement of cellular membranes and a strong innate immune antiviral response induction. So, we have included recent data explaining the mechanism by, even though viruses have evolved elegant hideouts, host cells are still able to develop dsRNA receptors-dependent antiviral response.
Ramirez, DA ;Locatelli, DA ; Torres-Palazzolo, CA ; Altamirano, JC ; Camargo, AB ; FOOD CHEMISTRY ,2017 ,215 ,493 -500 .
Organosulphur compounds (OSCs) present in garlic (Allium sativum L.) are responsible of several biological properties. Functional foods researches indicate the importance of quantifying these compounds in food matrices and biological fluids. For this purpose, this paper introduces a novel methodology based on dispersive liquid-liquid microextraction (DLLME) coupled to high performance liquid chromatography with ultraviolet detector (HPLC-UV) for the extraction and determination of organosulphur compounds in different matrices. The target analytes were allicin, (E)- and (Z)-ajoene, 2-vinyl-4H-1,2-dithiin (2-VD), diallyl sulphide (DAS) and diallyl disulphide (DADS). The microextraction technique was optimized using an experimental design, and the analytical performance was evaluated under optimum conditions. The desirability function presented an optimal value for 600 mu L of chloroform as extraction solvent using acetonitrile as dispersant. The method proved to be reliable, precise and accurate. It was successfully applied to determine OSCs in cooked garlic samples as well as blood plasma and digestive fluids. (C) 2016 Elsevier Ltd. All rights reserved.
Masone, D ;Gojanovich, AD ; Frontini-Lopez, YR ; Del Veliz, S ; Uhart, M ; Bustos, DM ; BIOCELL ,2017 ,41 ,55 -58 .
In this study, we propose an automatic procedure for digital image processing. We describe a method that can efficiently quantify and characterize lipid droplets distributions in different cell types in culture. Prospectively, the lipid droplets detection method described in this work could be applied to static or time-lapse data, collected with a simple visible light or fluorescence microscopy equipment. Fully automated algorithms were implemented in Octave, a freely available scientific package.
Koch, E ;Vega, IA ; Castro-Vazquez, A ; BIOCELL ,2017 ,41 ,59 -61 .
The digestive gland of the apple snail Pomacea canaliculata lodges two types of pigmented corpuscles (identified as C and K corpuscles) which has been proposed as endosymbiont/s. Both corpuscular types are always present in the digestive gland of adult snails, they are released into the tubuloacinar lumen and are later expelled in the feces. On their part, hatchlings lack any C or K corpuscles in the digestive gland as well as in their feces, whereas C corpuscles appear in both the gland and feces within one week after hatching. Hence, it is possible that the detritivorous hatchlings acquire the putative C-endosymbiont from feces in the sediments where they live, i.e. through 'lateral' or 'horizontal' transmission. This possibility was put to test in an experiment in which we prevented any lateral transmission, by a 7-days aseptic culture, with no food, of aseptically obtained hatchlings. At the end of the experiment, we observed that most juveniles had survived the culture period, and hence the digestive glands and feces of survivors were studied by light microscopy of resin embedded, toluidine blue-stained sections. All studied glands and fecal samples showed C corpuscles. It is concluded that lateral transmission of the endosymbiont, if any, is not indispensable for the acquisition of the endosymbiont by hatchlings.
Barberena, R ;Villanueva, GR ; Lucero, G ; Fernandez, MV ; Rughini, AA ; Sosa, P ; ESTUDIOS ATACAMENOS ,2017 ,,57 -75 .
The analysis of internodal spaces in archaeological scale offers a frame useful for integrating questions produced from different theoretical stands, which are actually complementary. The goal of this paper is to assess the role of internodal spaces for inter-group interaction in northern Patagonia from a biogeographical perspective. First, we present the theoretical-methodological frame that guides this proposal. There is important geographical and ecological variation in those parts of a given landscape that can be considered as internodes during the past, which should be characterized as a first step to assess their socio-demographic dynamics. We suggest that there are two key ecological variables that make up the basis of internodes: a) gradient of ecological variation in resources; b) spatial scale of the internodes. Secondly, based on ethnographic information, we describe in a simple manner the possible social mechanisms of interaction that structure and regulate the access to and circulation across internodes. By using this frame, we intend to model the archaeological dynamics of the human use of internodal areas in northern Patagonia. In third place, we explore the role of two lines of research that may constitute proxies on social interaction and circulation of information/objects in space: rock art and obsidian geochemistry. Finally, we consider the preliminary contribution of this research, suggesting paths for future development of these ideas.
Pinna, EG ;Ruiz, MC ; Ojeda, MW ; Rodriguez, MH ; HYDROMETALLURGY ,2017 ,167 ,66 -71 .
This paper presents the study of an innovative process: the reductive dissolution of mixed lithium cobalt oxide contained in the cathodes of spent Li-ion batteries with phosphoric acid. The studied parameters were: reaction time, temperature, stirring speed, solid-liquid ratio and concentrations of the leaching agent (H3PO4) and the reducing agent (H2O2). Reactants and products were characterized by atomic absorption spectroscopy (AAS), X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The results showed that the reducing dissolution process with phosphoric acid is an efficient way for the extraction of lithium and cobalt, achieving dissolution values close to 100%. In addition, a recovery of 88% of Li + as Li3PO4 and 99% of Co+2 as CoC2O4, with purities of 98.3% and 97.8% was found respectively. (C) 2016 Elsevier B.V. All rights reserved.
Evans, PD ;Mundo, IA ; Wiemann, MC ; Chavarria, GD ; McClure, PJ ; Voin, D ; Espinoza, EO ; IAWA JOURNAL ,2017 ,38 ,266 -+ .
Determining the species source of logs and planks suspected of being Araucaria araucana (Molina) K. Koch (CITES Appendix I) using traditional wood anatomy has been difficult, because its anatomical features are not diagnostic. Additionally, anatomical studies of Araucaria angustifolia (Bertol.) Kuntze, Araucaria heterophylla (Salisb.) Franco, Agathis australis (D. Don) Lindl., and Wollemia nobilis W. G. Jones, K. D. Hill & J. M. Allen have reported that these taxa have similar and indistinguishable anatomical characters from A. araucana. Trans-national shipments of illegal timber obscure their geographic provenance, and therefore identification using wood anatomy alone is insufficient in a criminal proceeding. In this study we examine the macroscopic appearance of selected members of the Araucariaceae and investigate whether analysis of heartwood chemotypes using Direct Analysis in Real Time (DART) Time-of-Flight Mass Spectrometry (TOFMS) is useful for making species determinations. DART TOFMS data were collected from 5 species (n = 75 spectra). The spectra were analyzsed statistically using supervised and unsupervised classification algorithms. Results indicate that A. araucana can be distinguished from the look-alike taxa. Another statistical inference of the data suggests that Wollemia nobilis is more similar and within the same clade as Agathis australis. We conclude that DART TOFMS spectra can help in making species determination of the Araucariaceae even when the geographic provenance is unknown.
Vitale, N ;Gonzalez, VH ; Vazquez, DP ; JOURNAL OF APICULTURAL RESEARCH ,2017 ,56 ,497 -509 .
Using a total of 14,043 trap-nests (potential nest for bees), we documented the nest architecture, host plants, seasonality, and associated organisms of the following six native species of Anthidium (Megachilidae: Anthidiini) from the Central Monte Desert in Mendoza, Argentina: A. andinum Jo "rgensen; A. chubuti Cockerell; A. decaspilum Moure; A. friesei Cockerell; A. rubripes Friese; and A. vigintipunctatum Friese. Each species exhibited unique features in the arrangement of the fibers used to make their cells, and in the type of material used in the nest plug. Bees used a total of 41 plant species, but relied heavily on Prosopis flexuosa (Fabaceae) and Larrea spp. (Zygophyllaceae). Most bee species are univoltine and exhibited delayed emergence. The oil beetle Nemognatha sp. (Coleoptera: Meloidae) and the cuckoo wasp Chrysis striatula Bohart (Hymenoptera: Chrysididae) are recorded for the first time for Anthidium. Nemognatha sp. was the most common brood parasite but C. striatula caused the highest brood mortality.
Klug, J ;Masone, D ; Del Popolo, MG ; RSC ADVANCES ,2017 ,7 ,30862 -30869 .
Solutions of the cationic amino-acid arginine (Arg(+)) in contact with a phospholipid monolayer are investigated by molecular dynamics simulations. The results show that Arg(+) binds strongly to the lipid/water interface, with adsorption free-energies ranging from -43.8 to -22.2 kJ mol(-1), depending on the amino-acids concentration. The large binding energies are attributed to hydrogen bonding between the charged moieties Arg(+) and the phosphate and carbonyl groups of the phospholipids, that compensate for changes in the levels of hydration upon adsorption. We show that a concentrated layer of Arg(+), tightly bound to the interface, has little effect on the compression isotherm and the lateral mechanical properties of the monolayer, while having a substantial impact on the interfacial electrostatic potential and the lateral mobility of the lipids. These effects are readily explained in terms of the arrangement that the amino-acids adopt when bound to the monolayer.
Castro-Grijalba, A ;Reyes-Gallardo, EM ; Wuilloud, RG ; Lucena, R ; Cardenas, S ; RSC ADVANCES ,2017 ,7 ,42979 -42985 .
In the present article a new approach for the synthesis of magnetic polymeric ionic liquid nanocomposites based on the Radziszewski reaction is presented. The Radziszewski reaction is a simple and successful procedure to obtain imidazolium-containing polymers under mild conditions and consists of the reaction between diamine compounds, glyoxal and formaldehyde in an acidic media. If magnetic nanoparticles coated with amino groups are introduced, they can participate as polyamines in the synthesis thus providing a final nanocomposite where polymeric ionic liquids and nanoparticles are combined. The resulting nanocomposite has been characterized using several instrumental techniques aimed at elucidating its chemical composition (infrared spectroscopy and elemental analysis), properties (zeta potential) and morphology (microscopy, X-ray diffraction and dynamic light scattering). Finally, its sorptive ability towards three non-steroidal anti-inflammatory drugs (NSAIDs) such as salicylic acid, ketoprofen and naproxen was evaluated considering the main variables involved in the process. According to the results, the polymeric ionic liquid nanocomposite is a promising sorptive material for analytical purposes.
Ito, M ;Appel, AP ; de Santana, VF ; Moyano, LG ; MEDINFO 2017: PRECISION HEALTHCARE THROUGH INFORMATICS ,2017 ,245 ,412 -416 .
Care teams are formed by physicians of different specialties who take care of the same patient. Hence, if we find physicians that share patients with each other probably they configure an informal care team. Thus, the objective of this work is to explore the possibility of finding care teams using Social Network Analysis techniques in physician-physician networks where the physicians have patients in common. For this, we used healthcare insurance claims to build the network. There was the agreement on the metrics of degree and eigenvalue and of betweenness and closeness, also physicians with the 5 highest eigenvalues are highly interconnected. We discuss that the analysis of the physician-physician network with metrics of centrality is promising to reveal informal care teams. The high potential in calculating these metrics is verified from the results to evaluate member's performance and with that how to take actions to improve the work of the team.
Gonzalez, R ;Vidoni, M ; Locatelli, D ; Camargo, A ; INTERNATIONAL JOURNAL OF FOOD PROPERTIES ,2017 ,20 ,S1016 -S1024 .
In this study, the effects of two garlic-flavouring processes on quality parameters and the organosulphur compound profile were investigated. The results showed that the addition of fresh garlic increased acidity and peroxide values in all flavoured vegetable oils. Mono-, di-, and trisulphides were mainly present in aromatised oils, while allicin, ajoene, and vinyl-dithiins were found in macerated oils. Analyses of the principal components demonstrate that flavoured oils could be discriminated according to the flavouring processes. The experiments carried out in this study would allow one to predict the results of a flavouring procedure on an unknown sample and, consequently, its potential beneficial effects.
Persia, FA ;Rinaldini, E ; Carrion, A ; Hapon, MB ; Gamarra-Luques, C ; MEDICINA-BUENOS AIRES ,2017 ,77 ,283 -290 .
Higher plants have provided various natural derived drugs used currently in western medicine. Tessaria absinthioides (Hook. & Arn.) DC, Asteraceae, is a native plant from South-America with reported ethnopharmacological and culinary uses. Despite recent scientific reports about plants properties, there is not a well conducted research about its anticancer and potential toxic effects. The current work demonstrates the plant aqueous extract composition; the in vitro induced cytotoxicity, and explores, in vivo, its oral toxicity and antitumoral effects. Composition of aqueous extract was determined by phytochemical reactions. Cytotoxicity was tested in tumoral (Hela, Gli-37, HCT-116 and MCF-7) and non-tumoral (HBL-100) cells, using MTT assay. Oral toxicity and the antitumor activity against colorectal carcinoma were studied in rodents. The chemical analysis revealed the presence of flavonoids, carbohydrates, sterols, terpenes and tannins. Cytotoxicity towards tumoral cells was observed (CV50: 3.0 to 14.8 mu g/ml); while in non-tumoral cells, extracts evidenced a selective reduced toxicity (CV50: 29.5 mu g/ ml). Oral administration of the extract does not induce acute nor dose-repeated toxicity at doses up to 2000 mg/kg and 1000 mg/kg/day, respectively. The antitumoral effect was confirmed by a significant increase in a median survival from 24 weeks (non-treated) to 30 weeks (T. absinthioides treated). The present data indicate that T. absinthioides extract exhibits cytotoxicity against cancer cell lines, with no-toxic effects and significant antitumoral effects in colorectal cancer when is orally administrated. In conclusion, T. absinthioides possesses selective cytotoxicity and antitumoral activities, making its plant derivatives products promising for cancer research and treatment.
Tramontina, DR ;Hahn, EN ; Meyers, MA ; Bringa, EM ; SHOCK COMPRESSION OF CONDENSED MATTER - 2015 ,2017 ,1793 ,-.
We simulate strong shock waves in nanocrystalline tantalum using atomistic molecular dynamics simulations, for particle velocities in the range 0.35-2.0 km s(-1), which induce pressures in the range 20-195 GPa. Our simulations explore strain rates in the range 108 s(-1) - 1010 s(-1), and lead to a peak strength in the range 3-15 GPa. Nanocrystalline tantalum exposed to strong shock waves demonstrates deformation enabled by concomitant dislocations, twinning, and grain boundary activity at a variety of particle velocities. Twinning is observed for a mean grain size of 7 nm, starting at around 32 GPa, in disagreement with models which predict a Hall-Petch behavior for twinning, i.e. a twinning stress scaling with grain size d as d(-0.5), and supporting the presence of an inverse Hall-Petch effect for twinning at small grain sizes.
Sassi, PL ;Cuevas, MF ; Menendez, J ; Dacar, MA ; ETHOLOGY ECOLOGY & EVOLUTION ,2017 ,29 ,351 -366 .
Knowledge of feeding habits not only contributes information related to the resources that individuals need to survive and breed, but also leads to insights about the interactions between a species and its environment. The optimal foraging theory explains diet selection by several attributes of the trophic scenario such as availability, diversity, quality and predictability of food. Other models propose that digestive tract mass increases under high metabolic demands by cold, affecting food choice and intake. Thus, diet selection emerges as a behavioural trait shaped by intrinsic and extrinsic factors. The goal of our study was to determine variation in the trophic scenario among sites at different elevations, as well as variation in phenotypic traits relevant to the nutritional and energy balance in Phyllotis xanthopygus. This small rodent is widely distributed along the Andes Mountains. We assessed diet selection and digestive tract size in individuals collected at three elevations across its distribution range. Results on dietary proportion of specific trophic categories (green parts, fruits and arthropods) showed that P. xanthopygus alternates between omnivory and granivory/frugivory. Richness, diversity and quality of the available resources evidenced a relatively low-quality trophic scenario at high altitude. Nevertheless, the diets built in by animals from diverse altitudes lacked differentiation in quality or diversity. P. xanthopygus seems to behaviourally compensate environmental variation to cope with nutritional requirements, by changing diet composition and proportion of items included. The resultant uniform diet quality is consistent with the absence of variation in the gastrointestinal tract size. Considering the spatial variability and seasonality of the region, a behavioural response is probably the most convenient strategy to overcome short-term environmental heterogeneity. In a plastic species such as P. xanthopygus, behaviour is a fundamental aspect to take into account by predictive models in the forecasts of climate change effects on biological diversity.
Fernandez, L ;Sanabria, EA ; Quiroga, LB ; ANIMAL BIODIVERSITY AND CONSERVATION ,2017 ,40 ,41 -47 .
Description of Silvinichthys pedernalensis n. sp. (Teleostei, Siluriformes) from the Andean Cordillera of southern South America.-Silvinichthys pedernalensis, a new species, is described from an Andean stream in Provincia San Juan, Argentina, based on its coloration pattern, and its meristic, morphometric and osteological characters. S. pedernalensis differs markedly from all other known members of the genus Silvinichthys as a result of the combination of the absence of pelvic girdle and fin, the wide supraorbital bone, the number of interopercle odontodes 14-18, the number of opercular odontodes 6-8, the branched pectoral-fin rays 7, the dorsal-fin rays 11, the number of dorsal pterygiophore 7, the branchiostegal rays 6, the dorsal procurrent caudal-fin rays 14 and ventral 15, the ribs 16, the vertebrae 39, the dark marmorated pigmentation on the body and head, the head depth 9.9-12.2% SL, the interorbital wide 28.3-36.1% HL, the nasal barbel length 27.3-39.0% SL, the maxillary barbel length 39.5-61.7% SL, the submaxillary barbel length 24.7-41.9% SL, the snout length 40.6-44.4% HL, the body depth 10.1-12.6% SL, the anal base fin 10.2-11.7% SL, and the caudal peduncle length 19.3-21.5% SL.
Cremades, PG ;Fernandez, RP ; Allende, DG ; Mulena, GC ; Puliafito, SE ; ATMOSFERA ,2017 ,30 ,11 -25 .
A proper representation of dust sources is critical to accurately predict atmospheric particle concentration in regional windblown dust simulations. The Weather Research and Forecasting model with Chemistry (WRF/Cheni) includes a topographic-based erodibility map originally conceived for global scale modeling, which fails to identify the geographical location of dust sources in many regions of Argentina. Therefore, this study aims at developing a method to obtain a high-resolution erodibility map suitable for regional or local scale modeling using WRF/Chem. We present two independent approaches based on global methods to estimate soil erodibility using satellite retrievals, i.e. topography from the Shuttle Radar Topography Mission (SRTM) and surface reflectance from the Moderate Resolution Imaging Spectroradiometer (MODIS). Simulation results of a severe Zonda wind episode in the arid central-west Argentina serve as bases for the analysis of these methods. Simulated dust concentration at surface level is compared with particulate matter measurements at one site in Mendoza city. In addition, we use satellite aerosol optical depth (AOD) retrievals to investigate model performance in reproducing spatial distribution of dust emissions. The erodibility map based on surface reflectance from MODIS improves the representation of small scale features, and increases the overall dust aerosol loading with respect to the standard map included by default. Simulated concentrations are in good agreement with measurements as well as satellite derived dust spatial distribution.
Segura, DM ;Masuelli, RW ; Sanchez-Puerta, MV ; GENOME ,2017 ,60 ,17 -25 .
Genomic analyses have shown that most genes in eukaryotic lineages belong to families. Gene families vary in terms of number of members, nucleotide similarity, gene integrity, expression, and function. Often, the members of gene families are arranged in clusters, which contribute to maintaining similarity among gene copies and also to generate duplicates through replication errors. Gene families offer us an opportunity to examine the forces involved in the evolution of the genomes and to study recombination events and genomic rearrangements. In this work, we focused on the evolution of two plant resistance gene families, Sw5 and Mi-1, and analyzed the completely sequenced nuclear genomes of potato and tomato. We first noticed that the potato genome carries larger resistance gene families than tomato, but all gene copies are pseudogenes. Second, phylogenetic analyses indicated that Sw5 and Mi-1 gene families had dissimilar evolutionary histories. In contrast to Sw5, Mi-1 homologues suffered repeated gene conversion events among the gene copies, particularly in the tomato genome.
Curiale, AH ;Colavecchia, FD ; Kaluza, P ; Isoardi, RA ; Mato, G ; 2017 XLIII LATIN AMERICAN COMPUTER CONFERENCE (CLEI) ,2017 ,,-.
Cardiac function is of paramount importance for both prognosis and treatment of different pathologies such as mitral regurgitation, ischemia, dyssynchrony and myocarditis. Cardiac behavior is determined by structural and functional features. In both cases, the analysis of medical imaging studies requires to detect and segment the myocardium. Nowadays, magnetic resonance imaging (MRI) is one of the most relevant and accurate non-invasive diagnostic tools for cardiac structure and function.
Camargo, AB ;Manucha, W ; CLINICA E INVESTIGACION EN ARTERIOSCLEROSIS ,2017 ,29 ,36 -45 .
Atherosclerosis, one of the main pathologic entities considered epidemic and a worldwide public health problem, is currently under constant review as regards its basic determining mechanisms and therapeutic possibilities. In this regard, all patients afflicted with the disease exhibit mitochondrial dysfunction, oxidative stress and inflammation. Interestingly, nitric oxide a known vasoactive messenger gas has been closely related to the inflammatory, oxidative and mitochondrial dysfunctional process that characterizes atherosclerosis. In addition, it has recently been demonstrated that alterations in the bioavailability of nitric oxide would induce the expression of heat shock proteins. This agrees with the use of functional foods as a strategy to prevent both vascular aging and the development of atherosclerosis. Finally, a greater knowledge regarding the mechanisms implied in the development of atherosclerosis will enable proposing new and possible hygiene, health and therapeutic interventions. (C) 2016 Sociedad Espanola de Arteriosclerosis. Published by Elsevier Espana, S.L.U. All rights reserved.
de la Fuente, MS ;Maniel, I ; Jannello, JM ; Sterli, J ; Riga, BG ; Novas, F ; CRETACEOUS RESEARCH ,2017 ,69 ,147 -168 .
A new genus and species of panchelid turtle (Mendozachelys wichmanni gen. et sp. nov.) from the upper Campanian-lower Maastrichtian Loncoche Formation (southern Mendoza Province, Argentina) is described here. This species is represented by only one complete and articulated large specimen (carapace length estimated in 950 mm) that was recovered from tidal flat deposits. A detailed morphological and osteohistological description is made, recognizing autapomorphic characters that allow differentiating this taxon from the rest of extant and extinct panchelids. Osteohistological characters suggest an aquatic to semi-aquatic life style for Mendozachelys wichmanni gen. et sp. nov. Phylogenetic analysis based on morphological data suggested that this new taxon is nested within crown Chelidae. Both phylogenetic signals (morphological and molecular) about the assessment of long-necked chelids monophyly or polyphyly are discussed. (C) 2016 Elsevier Ltd. All rights reserved.
Hossaini, R ;Chipperfield, MP ; Saiz-Lopez, A ; Fernandez, R ; Monks, S ; Feng, WH ; Brauer, P ; von Glasow, R ; JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES ,2016 ,121 ,14271 -14297 .
Chlorine atoms (Cl) are highly reactive toward hydrocarbons in the Earth's troposphere, including the greenhouse gas methane (CH4). However, the regional and global CH4 sink from Cl is poorly quantified as tropospheric Cl concentrations ([Cl]) are uncertain by similar to 2 orders of magnitude. Here we describe the addition of a detailed tropospheric chlorine scheme to the TOMCAT chemical transport model. The model includes several sources of tropospheric inorganic chlorine (Cly), including (i) the oxidation of chlorocarbons of natural (CH3Cl, CHBr2Cl, CH2BrCl, and CHBrCl2) and anthropogenic ( CH2Cl2, CHCl3, C2Cl4, C2HCl3, and CH2ClCH2Cl) origin and ( ii) sea-salt aerosol dechlorination. Simulations were performed to quantify tropospheric [Cl], with a focus on the marine boundary layer, and quantify the global significance of Cl atom CH4 oxidation. In agreement with observations, simulated surface levels of hydrogen chloride (HCl), the most abundant Cl-y reservoir, reach several parts per billion (ppb) over polluted coastal/continental regions, with sub-ppb levels typical in more remote regions. Modeled annual mean surface [Cl] exhibits large spatial variability with the largest levels, typically in the range of 1-5x10(4) atoms cm(-3), in the polluted northern hemisphere. Chlorocarbon oxidation provides a tropospheric Cly source of up to similar to 4320 Gg Cl/yr, sustaining a background surface [Cl] of < 0.1 to 0.5 x 10(3) atoms cm(-3) over large areas. Globally, we estimate a tropospheric methane sink of similar to 12-13 Tg CH4/yr due the CH4 + Cl reaction (similar to 2.5% of total CH4 oxidation). Larger regional effects are predicted, with Cl accounting for similar to 10 to > 20% of total boundary layer CH4 oxidation in some locations.
Gonzalez, CV ;Jofre, MF ; Vila, HF ; Stoffel, M ; Bottini, R ; Giordano, CV ; PLOS ONE ,2016 ,11 ,-.
Plants have evolved an array of specific photoreceptors to acclimate to the light environment. By sensing light signals, photoreceptors modulate plant morphology, carbon-and water-physiology, crop yield and quality of harvestable organs, among other responses. Many cultural practices and crop management decisions alter light quantity and quality perceived by plants cultivated in the field. Under full sunlight, phytochromes perceive high red to far red ratios (R:FR; 1.1), whereas overhead or lateral low R:FR (below 1.1) are sensed in the presence of plant shade or neighboring plants, respectively. Grapevine is one of the most important fruit crops in the world. To date, studies on grapevine response to light focused on different Photosynthetic Active Radiation (PAR) levels; however, limited data exist about its response to light quality. In this study we aimed to investigate morphological, biochemical, and hydraulic responses of Vitis vinifera to variations in R:FR. Therefore, we irradiated Syrah and Torronte's Riojano plants, grown in a glasshouse, with lateral FR light (low lateral R:FR treatment), while others, that were kept as controls, were not irradiated (ambient lateral R:FR treatment). In response to the low lateral R:FR treatment, grapevine plants did not display any of the SAS morphological markers (i.e. stem length, petiole length and angle, number of lateral shoots) in any of the cultivars assessed, despite an increase in gibberelins and auxin concentrations in leaf tissues. Low lateral R:FR did not affect dry matter partitioning, water-related traits (stomata density and index, wood anatomy), or water-related physiology (plant conductance, transpiration rate, stem hydraulic conductivity, stomatal conductance). None of the Vitis vinifera varieties assessed displayed the classical morphological and hydraulic responses associated to SAS induced by phytochromes. We discuss these results in the context of natural grapevine environment and agronomical relevance.
Rosales, GD ;Ruiz, MC ; Rodriguez, MH ; MINERALS ,2016 ,6 ,-.
Parameters affecting the kinetics of the dissolution of beta-spodumene with hydrofluoric acid have been investigated. The experimental tests were carried out in a closed vessel. The influence of several parameters, such as stirring speed, temperature, and reaction time were studied in order to deduce the kinetics of the dissolution reaction. The other parameters, particle size-45 m; HF concentration 4% v/v, and the solid-liquid ratio 0.95% w/v were kept constant. The results indicate that the stirring speed does not have an important effect on the dissolution of the mineral above 330 rpm. The extent of the leaching of beta-spodumene increases with temperature and reaction time augmentations. Scanning electron microscope (SEM) analyses of some residues in which the conversion was lower than 30% indicated a selective attack on certain zones of the particle. The treatment of the experimental data was carried out using the Modelado software. The model that best represents the dissolution of the mineral is the following: ln(1- X) =-b(1) [ln(1 + b(2)t)- b(2)t/(1 + b(2)t)]. This model is based on nucleation and growth of nuclei theory, and describes the style of attack physically observed by SEM on the residues.
Mutlu, B ;Veas, E ; Trattner, C ; ACM TRANSACTIONS ON INTERACTIVE INTELLIGENT SYSTEMS ,2016 ,6 ,-.
Visualizations have a distinctive advantage when dealing with the information overload problem: Because they are grounded in basic visual cognition, many people understand them. However, creating proper visualizations requires specific expertise of the domain and underlying data. Our quest in this article is to study methods to suggest appropriate visualizations autonomously. To be appropriate, a visualization has to follow known guidelines to find and distinguish patterns visually and encode data therein. A visualization tells a story of the underlying data; yet, to be appropriate, it has to clearly represent those aspects of the data the viewer is interested in. Which aspects of a visualization are important to the viewer? Can we capture and use those aspects to recommend visualizations? This article investigates strategies to recommend visualizations considering different aspects of user preferences. A multi-dimensional scale is used to estimate aspects of quality for visualizations for collaborative filtering. Alternatively, tag vectors describing visualizations are used to recommend potentially interesting visualizations based on content. Finally, a hybrid approach combines information on what a visualization is about (tags) and how good it is (ratings). We present the design principles behind VizRec, our visual recommender. We describe its architecture, the data acquisition approach with a crowd sourced study, and the analysis of strategies for visualization recommendation.
Munoz, AA ;Gonzalez-Reyes, A ; Lara, A ; Sauchyn, D ; Christie, D ; Puchi, P ; Urrutia-Jalabert, R ; Toledo-Guerrero, I ; Aguilera-Betti, I ; Mundo, I ; Sheppard, PR ; Stahle, D ; Villalba, R ; Szejner, P ; LeQuesne, C ; Vanstone, J ; CLIMATE DYNAMICS ,2016 ,47 ,4051 -4066 .
As rainfall in South-Central Chile has decreased in recent decades, local communities and industries have developed an understandable concern about their threatened water supply. Reconstructing streamflows from tree-ring data has been recognized as a useful paleoclimatic tool in providing long-term perspectives on the temporal characteristics of hydroclimate systems. Multi-century long streamflow reconstructions can be compared to relatively short instrumental observations in order to analyze the frequency of low and high water availability through time. In this work, we have developed a Biobio River streamflow reconstruction to explore the long-term hydroclimate variability at the confluence of the Mediterranean-subtropical and the Temperate-humid climate zones, two regions represented by previous reconstructions of the Maule and Puelo Rivers, respectively. In a suite of analyses, the Biobio River reconstruction proves to be more similar to the Puelo River than the Maule River, despite its closer geographic proximity to the latter. This finding corroborates other studies with instrumental data that identify 37.5A degrees S as a latitudinal confluence of two climate zones. The analyzed rivers are affected by climate forcings on interannual and interdecadal time-scales, Tropical (El Nio Southern Oscillation) and Antarctic (Southern Annular Mode; SAM). Longer cycles found, around 80-years, are well correlated only with SAM variation, which explains most of the variance in the Biobio and Puelo rivers. This cycle also has been attributed to orbital forcing by other authors. All three rivers showed an increase in the frequency of extreme high and low flow events in the twentieth century. The most extreme dry and wet years in the instrumental record (1943-2000) were not the most extreme of the past 400-years reconstructed for the three rivers (1600-2000), yet both instrumental record years did rank in the five most extreme of the streamflow reconstructions as a whole. These findings suggest a high level of natural variability in the hydro-climatic conditions of the region, where extremes characterized the twentieth century. This information is particularly useful when evaluating and improving a wide variety of water management models that apply to water resources that are sensitive to agricultural and hydropower industries.
Amiri, F ;Millan, D ; Arroyo, M ; Silani, M ; Rabczuk, T ; COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING ,2016 ,312 ,254 -275 .
We apply a fourth order phase-field model for fracture based on local maximum entropy (LME) approximants. The higher order continuity of the meshfree LME approximants allows to directly solve the fourth order phase-field equations without splitting the fourth order differential equation into two second order differential equations. We will first show that the crack surface can be captured more accurately in the fourth order model. Furthermore, less nodes are needed for the fourth order model to resolve the crack path. Finally, we demonstrate the performance of the proposed meshfree fourth order phase-field formulation for 5 representative numerical examples. Computational results will be compared to analytical solutions within linear elastic fracture mechanics and experimental data for three-dimensional crack propagation. (C) 2016 Elsevier B.V. All rights reserved.
Marsh, E ;Cortegoso, V ; Castro, S ; QUATERNARY INTERNATIONAL ,2016 ,422 ,66 -80 .
In the southern Andes, Holocene climate records show drastic changes in moisture during the early and middle Holocene. To generate a more refined chronology of climate changes in this region, we present a Bayesian model that combines published cosmogenic dates from the Encierro Valley (29.1 degrees S) and radiocarbon dates on peat and soils from the western slope of the Andes (27-33 degrees S). We compare this to a similar model from the high-altitude archaeological site ARQ-18 in the Las Taguas Valley (29.5 degrees S), San Juan, Argentina. These chronologies indicate synchronous changes in climate and occupational intensity, which shed light on hunter-gatherer mobility decisions. This site was first occupied in the early Holocene, when nearby valleys were deglaciated by around 10,700 cal BP. ARQ-18 was occupied a few centuries later around 10,100 cal BP. The site was first colonized during a regional wet phase, probably by hunters from the highlands to north who moved quickly among humid high-altitude valleys. As regional moisture began dropping around 8700-7800 cal BP, occupational intensity at ARQ-18 reached a maximum as diverse groups gathered in the valley. At this point, an important environmental threshold was crossed as groups reversed their mobility patterns and decisions and did not occupy the site for 1700 years. This "archaeological silence" correlates closely with the middle Holocene's hyperaridity during 7800-5700 cal BP. As soon as humidity returned, groups began visiting the site again. From this point on, strategies increasingly incorporated herding in response to less stable environmental conditions. (C) 2015 Elsevier Ltd and INQUA. All rights reserved.
Cortegoso, V ;Barberena, R ; Duran, V ; Lucero, G ; QUATERNARY INTERNATIONAL ,2016 ,422 ,81 -92 .
We have carried out long-term comparative in a wide latitudinal range of the Andes (29 degrees - 37 degrees south), encompassing selected areas that differ in ecology and biogeography. This latitudinal span shows diversity in subsistence modes across time and space, ranging from Andean agro-pastoralists in the north to Patagonian hunter-gatherers in the south. As part of this research, a program of geochemical and archaeological characterization of obsidian sources and distributions is being developed, attempting to assess connections between different biogeographical contexts. This work has allowed recognizing five Andean sources with different geological and topographical properties. Stemming from this macro-regional endeavor, in this paper we present a comparative analysis of the human use of two sources that, based on the intensity of human use on a macro-regional scale, can be interpreted as 'minor' sources.
Marsh, EJ ;QUATERNARY INTERNATIONAL ,2016 ,422 ,123 -134 .
The mid-Holocene was an extremely dry period in the Lake Titicaca Basin of South America, when lake levels were at their lowest point in the Holocene. South of the lake, a lack of outflow and very low and irregular precipitation would have created desert-like conditions. This area's 'archaeological silence' seems to reflect an effective lack of population. This situation changed drastically as lake levels rose suddenly in the centuries following 3540 cal BP. As the desert disappeared, a flux of migrants filled the landscape, probably from the population concentration in the basin's western highlands. They imported and developed new technologies and economic practices and reorganized them into an agropastoral lifeway. The emergence of agropastoralism was both rapid and widespread, as people throughout the Lake Titicaca Basin adopted this practice. This major, regional shift can be productively framed as an adaptive cycle or Holling loop. This approach builds on the robust foundation of complexity theory, emphasizes the integrated nature of humans and their environment in a single system, highlights how systems fluctuate between slow and accelerated change, and is useful for developing hypotheses. Cascading feedback loops in climate, ecology, and cultural practices generated the emergence of agropastoralism. This resilient system is still in use today and is currently facing major climate changes, which makes understanding its origins especially relevant. (C) 2016 Elsevier Ltd and INQUA. All rights reserved.
Frigole, C ;Gasco, A ; QUATERNARY INTERNATIONAL ,2016 ,422 ,152 -162 .
This study addresses the risk-management activities of Andean pastoralists in northwestern, Mendoza. We compare data from one high-altitude site, Agua de la Cueva, located near a spring and an excellent hunting ground, and a domestic pit house at the site San Ignacio in a nearby mountain valley. We analyze data from roughly contemporaneous contexts dating to 1100-1400 cal BP. Osteometric measurements of camelid post-cranial bones and comparisons to modern camelids with multivariate statistics confirmed the presence of wild guanacos and vicunas as well as castrated and uncastrated domestic llamas. Hence, this is one of the southernmost areas where Andean pastoralism was practiced. Petrographic analysis of pottery and comparisons to local geology suggest strong similarities between the sites. Similar fabrics suggest a closely-connected group that probably made effective and complementary use of these two environments. Previous studies have established the presence of vessels from the other side of the Andes indicating long-distance contacts between populations on both sides of the Andes. These contacts may have been made via caravans that included castrated llamas, which are ethnographically preferred among drovers. The possibility of caravans is a hypothesis to be tested with future research. Our data suggest these groups participated in seasonal and perhaps long-distance movements in addition to other activities such as hunting, herding, and storing food. The combination of these risk-management strategies provided a stable economic base for the potters and herders of northwestern Mendoza. This case can be broadly compared to better-known archaeological and ethnographic examples from other parts of the Andes. (C) 2016 Elsevier Ltd and INQUA. All rights reserved.
Lima, NW ;Gutierres, LI ; Gonzalez, RI ; Muller, S ; Thomaz, RS ; Bringa, EM ; Papaleo, RM ; PHYSICAL REVIEW B ,2016 ,94 ,-.
In this paper, the surface effects of individual heavy ions impacting thin polymerlike films were investigated, using molecular dynamics simulations with the finite extensible nonlinear elastic (FENE) potential to describe the molecular chains. The perturbation introduced by the ions in the lattice was modeled assuming that the initial excitation energy in the ion track is converted into an effective temperature, as in a thermal spike. The track was heated only within the film thickness h, leaving a nonexcited substrate below. The effect of decreasing thickness on cratering and sputtering was evaluated. The results were compared to experimental data of thin polymer films bombarded by MeV-GeV ions and to simulations performed with the Lennard-Jones potential. While several qualitative results observed in the experiments were also seen in the simulations, irrespective of the potential used, there are important differences observed on FENE films. Crater dimensions, rim volume, and sputtering yields are substantially reduced, and a threshold thickness for molecular ejection appears in FENE simulations. This is attributed to the additional restrictions on mass transport out of the excited track region imposed by interchain interactions (entanglements) and by the low mobility of the molten phase induced by the spike.
Millan, EN ;Goiran, S ; Forconesi, L ; Aranibar, JN ; Garino, CG ; Bringa, EM ; ECOLOGICAL INFORMATICS ,2016 ,36 ,135 -144 .
We developed an open source Monte Carlo based model to simulate Settlement Dynamics in Drylands (SeDD). The model assigns partial probabilities to each pixel within a grid region, based on several factors that can influence the establishment and subsistence of settlements: groundwater depth, vegetation type, proximity to rivers, paved roads, old river beds, and existing settlements. Partial probabilities are considered to be independent from each other, and therefore multiplied to calculate an overall probability for each pixel. Settlements are assigned by maximum probabilities or randomly, according to pre-established threshold probability values. We also modeled the gradual reduction of vegetation caused by a new settlement in neighboring pixels, decreasing the probabilities related to vegetation type. The final distribution of settlements is given by an average over multiple Monte Carlo simulations. The model is computationally efficient and could be used to rapidly explore different scenarios of settlement dynamics and vegetation degradation in arid environments, and other environmental factors that can be added to the framework without performing changes in the source code. (C) 2016 Elsevier B.V. All rights reserved.
Aguilera, AC ;Boschin, V ; Carvelli, L ; Cavicchia, JC ; Sosa, MA ; JOURNAL OF CELLULAR BIOCHEMISTRY ,2016 ,117 ,2464 -2472 .
Glycosidases may play a role in sperm maturation during epididymal transit. In this work, we describe the interaction of these enzymes with bull spermatozoa. We found that -galactosidase associated to spermatozoa can be released under low ionic strength conditions, whereas the interaction of N-acetyl--D-glucosaminidase and -glucuronidase with spermatozoa appeared to be stronger. On the other hand, -mannosidase and -fucosidase cannot be removed from the gametes. In addition, part of N-acetyl--D-glucosaminidase, -galactosidase, and -glucuronidase can also be released by mannose-6-phosphate. Taking into account these data, we explored the presence of cation-independent- and cation-dependent-mannose-6-phosphate receptors in the spermatozoa and found that cation-independent mannose-6-phosphate receptor is highly expressed in bull spermatozoa and cation-dependent-mannose-6-phosphate receptor is expressed at a lesser extent. In addition, by immunofluorescence, we observed that cation-independent-mannose-6-phosphate receptor is mostly located at the acrosomal zone, whereas cation-dependent-mannose-6-phosphate receptor presents a different distribution pattern on spermatozoa during the epididymal transit. N-acetyl--D-glucosaminidase and -glucuronidase isolated from epididymal fluid interacted mostly with cation-independent-mannose-6-phosphate receptor, while -galactosidase was recognized by both receptors. We concluded that glycosidases might play different roles in bull spermatozoa and that mannos-6-phosphate receptors may act as recruiters of some enzymes. J. Cell. Biochem. 117: 2464-2472, 2016. (c) 2016 Wiley Periodicals, Inc.
Valencia, FJ ;Gonzalez, RI ; Tramontina, D ; Rogan, J ; Valdivia, JA ; Kiwi, M ; Bringa, EM ; JOURNAL OF PHYSICAL CHEMISTRY C ,2016 ,120 ,23836 -23841 .
The potential and properties of palladium hollow nano particles (hNPs) as a possible H storage material are explored by means of classical molecular dynamics (MD) simulations. First, we study the stability of pure Pd hNPs for different sizes and thicknesses, obtaining good agreement with experimental results for nanometer size Pd hNP. Next we add, every 100 fs, single H atoms into the NP cavity. During the first stages of the simulation, our results show hydride formation on the inner surface, similar to what has been observed in experiments on Pd surfaces and NPs. Formation of the Pd hydride decreases the absorption rate, and H gas is formed inside the cavity. The maximum H gas pressure that is reached is of 7 GPa, before fractures appear in the hNP, and consequently the hNP breaks up. We obtain a maximum H/Pd ratio of 1.21 when H is introduced only inside the cavity. However, when H is deposited both on the inside and outside surfaces, this ratio reaches 1.70, which is 25% larger than previous reports. Beyond this ratio, the hNP breaks up, and the H gas is ejected from the hNP cavity.
Martinis, EM ;Wuilloud, RG ; SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY ,2016 ,167 ,111 -115 .
This article presents an efficient, simple, and cost-effective method for the determination of trace amounts of Hg by vortex-assisted liquid-liquid microextraction (VALLME) coupled to microvolume UV-Vis spectrophotometry. This method correlates changes in the intensity of localized surface plasmon resonance (LSPR) of tetraoctylammonium bromide (TOABr) coated Au nanoparticles (NPs) after interaction with Hg2+ ion. Spectroscopic measurements of the TOABr-coated Au NPs phase with particular absorption properties (strong and well-defined absorption bands) after analyte extraction by VALLME, provide an accurate and sensitive determination of Hg in water samples, comparable with measurements obtained by atomic absorption spectrometry (AAS). Different variables including sample volume, extraction time, and TOABr-coated Au NPs dispersion volume were carefully studied; final experimental conditions were 5 mL, 120 mu L and 5 min respectively. The limit of detection (LOD) was 0.8 ng mL(-1). The calibration curve was linear at concentrations between the limit of quantification (LOQ) (4.9 ng mL(-1)) and up to at least 120 ng mL(-1) of Hg. The relative standard deviation for six replicate determinations of 20 ng mL(-1) of Hg was 4.7%. This method exhibited an excellent analytical performance in terms of selectivity and sensitivity and it was finally applied for Hg determination in spiked tap and mineral water samples. (C) 2016 Elsevier B.V. All rights reserved.
Zodrow, EL ;D'Angelo, JA ; Taylor, WA ; Catelani, T ; Heredia-Guerrero, JA ; Mastalerz, M ; INTERNATIONAL JOURNAL OF COAL GEOLOGY ,2016 ,167 ,184 -200 .
Secretory organs likely evolved with land plants in Silurian-Devonian time, but it is questionable if they were passed on to living cycadaleans upon the extinction of seed ferns (Triassic-Jurassic?). They are defined as ducts of schizo-, lysig- or rhexigenous origin that exuded a heterogeneous lipoid mixture that fossilized as secretory products (droplets). In this study we detailed (1) the physical properties and distributions based on the compression-preserved Neuropteris ovata var. simonii and Laveineopteris rarinervis frond sections (Late Pennsylvanian Sydney Coalfield, Canada). Examined were also 1300 cuticular slides representing a number of plant groups, complemented by published data to infer biomass accumulation as potential kerogen in the geological column. In addition, (2) from select pinnules of the two species mentioned, nine secretory products and four surrounding cuticles were analyzed by micro-FTIR to evaluate statistically (PCA) the chemotaxonomic potential, and the kerogen chemistry. Further studies in support of (1), or (2) included methods of NICI, SEM, TEM and AFM, and by EDS.
Bello, OD ;Cappa, AI ; de Paola, M ; Zanetti, MN ; Fukuda, M ; Fissore, RA ; Mayorga, LS ; Michaut, MA ; EXPERIMENTAL CELL RESEARCH ,2016 ,347 ,42 -51 .
Fusion of cortical granules with the oocyte plasma membrane is the most significant event to prevent polyspermy. This particular exocytosis, also known as cortical reaction, is regulated by calcium and its molecular mechanism is still not known. Rab3A, a member of the small GTP-binding protein superfamily, has been implicated in calcium-dependent exocytosis and is not yet clear whether Rab3A participates in cortical granules exocytosis. Here, we examine the involvement of Rab3A in the physiology of cortical granules, particularly, in their distribution during oocyte maturation and activation, and their participation in membrane fusion during cortical granule exocytosis. Immunofluorescence and Western blot analysis showed that Rab3A and cortical granules have a similar migration pattern during oocyte maturation, and that Rab3A is no longer detected after cortical granule exocytosis. These results suggested that Rab3A might be a marker of cortical granules. Overexpression of EGFP-Rab3A colocalized with cortical granules with a Pearson correlation coefficient of +0.967, indicating that Rab3A and cortical granules have almost a perfect colocalization in the egg cortical region. Using a functional assay, we demonstrated that microinjection of recombinant, prenylated and active GST-Rab3A triggered cortical granule exocytosis, indicating that Rab3A has an active role in this secretory pathway. To confirm this active role, we inhibited the function of endogenous Rab3A by microinjecting a polyclonal antibody raised against Rab3A prior to parthenogenetic activation. Our results showed that Rab3A antibody microinjection abolished cortical granule exocytosis in parthenogenetically activated oocytes. Altogether, our findings confirm that Rab3A might function as a marker of cortical granules and participates in cortical granule exocytosis in mouse eggs. (C) 2016 Elsevier Inc. All rights reserved.
Grijalba, AC ;Fiorentini, EF ; Martinez, LD ; Wuilloud, RG ; JOURNAL OF CHROMATOGRAPHY A ,2016 ,1462 ,44 -54 .
The application of different ionic liquids (ILs) as modifiers for chromatographic separation and determination of arsenite [As(III)], arsenate [As(V)], dimethylarsonic acid (DMA) and monomethylarsonic acid (MMA) species in wine samples, by reversed-phase high performance liquid chromatography coupled to hydride generation atomic fluorescence spectrometry detection (RP-HPLC-HG-AFS) was studied in this work. Several factors influencing the chromatographic separation of the As species, such as pH of the mobile phase, buffer solution concentration, buffer type, IL concentration and length of alkyl groups in ILs were evaluated. The complete separation of As species was achieved using a C-18 column in isocratic mode with a mobile phase composed of 0.5% (v/v) 1-octyl-3-methylimidazolium chloride ([C-8 mim]Cl) and 5% (v/v) methanol at pH 8.5. A multivariate methodology was used to optimize the variables involved in AFS detection of As species after they were separated by HPLC. The ILs showed remarkable performance for the separation of As species, which was obtained within 18 min with a resolution higher than 0.83. The limits of detection for As(III), As(V), MMA and DMA were 0.81, 0.89, 0.62 and 1.00 mu g As L-1. The proposed method was applied for As speciation analysis in white and red wine samples originated from different grape varieties. (C) 2016 Elsevier B.V. All rights reserved.
Curiale, AH ;Vegas-Sanchez-Ferrero, G ; Aja-Fernandez, S ; MEDICAL IMAGE ANALYSIS ,2016 ,32 ,184 -200 .
Speckle Tracking is one of the most prominent techniques used to estimate the regional movement of the heart based on ultrasound acquisitions. Many different approaches have been proposed, proving their suitability to obtain quantitative and qualitative information regarding myocardial deformation, motion and function assessment. New proposals to improve the basic algorithm usually focus on one of these three steps: (1) the similarity measure between images and the speckle model; (2) the transformation model, i.e. the type of motion considered between images; (3) the optimization strategies, such as the use of different optimization techniques in the transformation step or the inclusion of structural information. While many contributions have shown their good performance independently, it is not always clear how they perform when integrated in a whole pipeline. Every step will have a degree of influence over the following and hence over the final result. Thus, a Speckle Tracking pipeline must be analyzed as a whole when developing novel methods, since improvements in a particular step might be undermined by the choices taken in further steps. This work presents two main contributions: (1) We provide a complete analysis of the influence of the different steps in a Speckle Tracking pipeline over the motion and strain estimation accuracy. (2) The study proposes a methodology for the analysis of Speckle Tracking systems specifically designed to provide an easy and systematic way to include other strategies. We close the analysis with some conclusions and recommendations that can be used as an orientation of the degree of influence of the models for speckle, the transformation models, interpolation schemes and optimization strategies over the estimation of motion features. They can be further use to evaluate and design new strategy into a Speckle Tracking system. (C) 2016 Elsevier B.V. All rights reserved.
Beltrame, MO ;De Porras, ME ; Barberena, R ; Llano, CL ; Sardella, NH ; PARASITOLOGY INTERNATIONAL ,2016 ,65 ,352 -356 .
The present paper reports the first paleoparasitological results obtained from coprolites of fossil rodent middens and demonstrates the potential of rodent middens as a source of paleoparasitological evidences in South America. Ten fossil rodent middens from northwestern Patagonia, Argentina, were studied. Five coprolites of each midden were fully processed, rehydrated, homogenized, subjected to spontaneous sedimentation, and examined through light microscopy. Eight of the 10 examined rodent middens contained parasite eggs. The eggs of parasites were assigned to Heteroxynema (Cavioxyura) viscaciae Sutton & Hugot, 1989 and Helminthoxys sp. (Nematoda: Oxyuridae), Trichuris sp. (Nematoda: Trichuridae) and one unidentified nematode. Fossil rodent middens were assigned to Lagidium viscacia (Caviomorph: Chinchillidae). The excellent preservation of parasite remains in coprolites from fossil rodent middens provided an opportunity to perform paleoparasitological inferences. The results of this papers demonstrates that fossil rodent middens offer an excellent opportunity for the recovery of parasite remains for future paleoparasitological studies in the southwest of South America. (C) 2016 Elsevier Ireland Ltd. All rights reserved.
Dorado, J ;Vazquez, DP ; PEERJ ,2016 ,4 ,-.
Background: Diverse flower communities are more stable in floral resource production along the flowering season, but the question about how the diversity and stability of resources affect pollinator reproduction remains open. High plant diversity could favor short foraging trips, which in turn would enhance bee fitness. In addition to plant diversity, greater temporal stability of floral resources in diverse communities could favor pollinator fitness because such communities are likely to occupy the phenological space more broadly, increasing floral availability for pollinators throughout the season. In addition, this potential effect of flower diversity on bee reproduction could be stronger for generalist pollinators because they can use a broader floral spectrum. Based on above arguments we predicted that pollinator reproduction would be positively correlated to flower diversity, and to temporal stability in flower production, and that this relationship would be stronger for the most generalized pollinator species.
Gonzalez, RI ;Valencia, F ; Mella, J ; van Duin, ACT ; So, KP ; Li, J ; Kiwi, M ; Bringa, EM ; APPLIED PHYSICS LETTERS ,2016 ,109 ,-.
The improvement of radiation resistance in nanocomposite materials is investigated by means of classical reactive molecular dynamics simulations. In particular, we study the influence of carbon nanotubes (CNTs) in an Ni matrix on the trapping and possible outgassing of He. When CNTs are defect-free, He atoms diffuse alongside CNT walls and, although there is He accumulation at the metal-CNT interface, no He trespassing of the CNT wall is observed, which is consistent with the lack of permeability of a perfect graphene sheet. However, when vacancies are introduced to mimic radiation-induced defects, He atoms penetrate CNTs, which play the role of nano-chimneys, allowing He atoms to escape the damaged zone and reduce bubble formation in the matrix. Consequently, composites made of CNTs inside metals are likely to display improved radiation resistance, particularly when radiation damage is related to swelling and He-induced embrittlement. Published by AIP Publishing.
Gonzalez, RI ;Rogan, J ; Bringa, EM ; Valdivia, JA ; JOURNAL OF PHYSICAL CHEMISTRY C ,2016 ,120 ,14428 -14434 .
The mechanical response of aluminosilicate nano tubes (imogolite) under compression is investigated by means of classical molecular dynamics simulations using the CLAYFF potential. Using the uncompressed length L-0, when there is no strain, to describe each nanotube, we have found that imogolite tends to coil for L-0 > 15 nm to prevent the failure of the nanotube. The simulation also shows that the nanotubes do not break under stress for L-0 >= 100 nm. Hence, the imogolite is a very flexible nanotube, which has been observed with lengths up to 500 nm. Finally, we can report a Young modulus of the order of 200 GPa, which is relatively independent of L-0.
Campoy, EM ;Laurito, SR ; Branham, MT ; Urrutia, G ; Mathison, A ; Gago, F ; Orozco, J ; Urrutia, R ; Mayorga, LS ; Roque, M ; PLOS ONE ,2016 ,11 ,-.
During the last decades it has been established that breast cancer arises through the accumulation of genetic and epigenetic alterations in different cancer related genes. These alterations confer the tumor oncogenic abilities, which can be resumed as cancer hallmarks (CH). The purpose of this study was to establish the methylation profile of CpG sites located in cancer genes in breast tumors so as to infer their potential impact on 6 CH: i.e. sustained proliferative signaling, evasion of growth suppressors, resistance to cell death, induction of angiogenesis, genome instability and invasion and metastasis. For 51 breast carcinomas, MS-MLPA derived-methylation profiles of 81 CpG sites were converted into 6 CH profiles. CH profiles distribution was tested by different statistical methods and correlated with clinical-pathological data. Unsupervised Hierarchical Cluster Analysis revealed that CH profiles segregate in two main groups (bootstrapping 90-100%), which correlate with breast laterality (p = 0.05). For validating these observations, gene expression data was obtained by RealTime-PCR in a different cohort of 25 tumors and converted into CH profiles. This analyses confirmed the same clustering and a tendency of association with breast laterality (p = 0.15). In silico analyses on gene expression data from TCGA Breast dataset from left and right breast tumors showed that they differed significantly when data was previously converted into CH profiles (p = 0.033). We show here for the first time, that breast carcinomas arising on different sides of the body present differential cancer traits inferred from methylation and expression profiles. Our results indicate that by converting methylation or expression profiles in terms of Cancer Hallmarks, it would allow to uncover veiled associations with clinical features. These results contribute with a new finding to the better understanding of breast tumor behavior, and can moreover serve as proof of principle for other bilateral cancers like lung, testes or kidney.
Meglioli, PA ;Villagra, PE ; Aranibar, JN ; ECOHYDROLOGY ,2016 ,9 ,738 -752 .
In the woodlands of the Central Monte desert (Argentina), phreatophyte vegetation is exposed to different levels of disturbance. Livestock and settlement activity produce mainly nutrient inputs and partial vegetation removal, with a consequent reduction on water use by vegetation. We hypothesize that because of the increased soil water and nutrient resources associated with livestock stations, water stress will be relieved for the remaining Prosopis flexuosa trees, favouring water and nutrient status, and plant growth at the plant scale. The goal of this research was to analyse the physiological responses of P. flexuosa trees that grow in interdune valleys under different land uses, and the changes in relative importance of environmental factors controlling these responses. We compared the ecophysiological responses of adult P. flexuosa trees in two contrasting types of disturbance: disturbed (livestock stations) and relatively undisturbed (control woodlands) stands, in the 2011-2013 growing seasons. Pre-dawn and midday leaf water potential and stomatal conductance were higher in livestock stations than in control woodlands, suggesting a better water status of P. flexuosa in livestock stations. Isotopic composition (lower delta C-13, and higher delta N-15) and foliar nitrogen concentration (lower C:N ratios) indicated lower water use efficiency and higher nitrogen absorption from the soil in livestock stations. Both growth of new leaves (foliar area) and the length of young branches were higher in the first season for both land uses, but branch length was higher in livestock stations. This is consistent with the idea that vegetation removal and nutrient contribution of settlement activities improved water and nutrient status of remaining vegetation, and modified the relative importance of factors controlling ecophysiological processes. We concluded that physiological responses and vegetative growth of P. flexuosa were not only affected by meteorological conditions (rainfalls, vapour pressure deficit), but also by the ecohydrological changes caused by changes in land use. Copyright (C) 2015 John Wiley & Sons, Ltd.
Calori, A ;Santos, JR ; Blanco, M ; Pessano, H ; Llamedo, P ; Alexander, P ; de la Torre, A ; ATMOSPHERIC RESEARCH ,2016 ,176 ,267 -275 .
Mendoza is a province of Argentina located between 32 degrees S and 34 degrees S at the leeside of the Andes Foothills. Very intense thunderstorms form between October and March (southern hemisphere summer), which produce large hail and damage in crops and properties. Although some hypotheses and conceptual models were proposed in order to identify key possible mechanisms that contribute to trigger convection, they are still waiting for the validation process. As moisture is the main ingredient for storms formation, the identification of its geographical distribution could be used together with other synoptic and mesoscale forcing features to forecast intense convective events. A novel technique in estimating moisture concentration and its geographical distribution has been introduced in order to observe the influx and variability of humidity at this region, during a 45-day period in midsummer. In doing so, we resort to the information provided by the ground-basedGlobal Navigation Satellite System (GNSS) network. More than 300 active stations constitute the continuously operating GNSS network over Southern and Central America (SIRGAS-CON, Sistema de Referencia Geocentric para las Americas de Operation Continua). This network allows to retrieve integrated water vapor (IWV) content, mapping this variable by the use of a digital model of terrain. In the period and region under study, a prevailing influx of humidity from N and NE and a high correlation between the accumulation/depletion of humidity and the hail/no hail precipitation days is observed. We discuss in particular the development of five storms detected by the S-Band radar network belonging to the Province of Mendoza. Although the results strongly suggest that IWV maps are capable to represent the humidity dynamics in the considered region, it is still important to highlight that the calculated values for IWV are unrealistic at some locations as the consequence of deep atmospheric gradients. These biases may be explained by the fact that the GNSS observations are made over the whole horizon of each given site. (C) 2016 Elsevier B.V. All rights reserved.
Millan, EN ;Tramontina, DR ; Urbassek, HM ; Bringa, EM ; PHYSICAL REVIEW E ,2016 ,93 ,-.
While at small collision velocities collisions of nanoparticles (NPs) are elastic, they become plastic at higher velocities. We study the elastic-plastic threshold and the onset of plasticity using molecular dynamics simulation for a Lennard-Jones material. The reasons behind the R-2/3 increase of the threshold velocity for small NP radii R found recently are discussed. At the threshold, NP orientation strongly influences the generation of plasticity, and averaging over many orientations is required to predict the critical velocity for dislocation generation. The onset of plasticity is governed by the generation of isolated stacking faults and nanotwins spanning the entire NP. At higher velocities, the fraction of defects becomes proportional to the total number of atoms in the NP.
Kaluza, P ;Inoue, M ; EUROPEAN PHYSICAL JOURNAL B ,2016 ,89 ,-.
Genetic regulatory networks with adaptive responses are widely studied in biology. Usually, models consisting only of a few nodes have been considered. They present one input receptor for activation and one output node where the adaptive response is computed. In this work, we design genetic regulatory networks with many receptors and many output nodes able to produce delayed adaptive responses. This design is performed by using an evolutionary algorithm of mutations and selections that minimizes an error function defined by the adaptive response in signal shapes. We present several examples of network constructions with a predefined required set of adaptive delayed responses. We show that an output node can have different kinds of responses as a function of the activated receptor. Additionally, complex network structures are presented since processing nodes can be involved in several input-output pathways.
Gunkelmann, N ;Rosandi, Y ; Ruestes, CJ ; Bringa, EM ; Urbassek, HM ; COMPUTATIONAL MATERIALS SCIENCE ,2016 ,119 ,27 -32 .
Shock waves are produced in Al nanofoams by a piston moving with velocity U-p. They induce plastic activity in the ligaments before eventually the foam structure is crushed and a compact material results. We demonstrate dislocation formation in the foams and correlate it with the velocity and stress profiles in the shock wave. The profiles exhibit a 3-wave structure indicating 3 wave regimes: elastic precursor, plastic activity in the ligaments, and foam crushing. The shock wave velocity V follows well macroscopic predictions, V proportional to U-p. The length of the non-collapsed part of the foam is well described by an analytical compaction model. (C) 2016 Elsevier B.V. All rights reserved.
Acena, A ;Clement, MEG ; CLASSICAL AND QUANTUM GRAVITY ,2016 ,33 ,-.
We study deformations of axially symmetric initial data for Einstein-Maxwell equations satisfying time-rotation (t-phi) symmetry and containing one asymptotically cylindrical end and one asymptotically flat end. We find that the t-phi symmetry implies the existence of a family of deformed data having the same horizon structure. This result allows us to measure how close the solutions are to the Lichnerowicz equation when arising from nearby free data.
Hahn, EN ;Zhao, S ; Bringa, M ; Meyers, MA ; SCIENTIFIC REPORTS ,2016 ,6 ,-.
Dislocations are the primary agents of permanent deformation in crystalline solids. Since the theoretical prediction of supersonic dislocations over half a century ago, there is a dearth of experimental evidence supporting their existence. Here we use non-equilibrium molecular dynamics simulations of shocked silicon to reveal transient supersonic partial dislocation motion at approximately 15 km/s, faster than any previous in-silico observation. Homogeneous dislocation nucleation occurs near the shock front and supersonic dislocation motion lasts just fractions of picoseconds before the dislocations catch the shock front and decelerate back to the elastic wave speed. Applying a modified analytical equation for dislocation evolution we successfully predict a dislocation density of 1.5 x 10(12) cm(-2) within the shocked volume, in agreement with the present simulations and realistic in regards to prior and on-going recovery experiments in silicon.
Duran, V ;Winocur, D ; Stern, C ; Garvey, R ; Barberena, R ; Monne, JLP ; Benitez, A ; INTERSECCIONES EN ANTROPOLOGIA ,2016 ,17 ,33 -46 .
A prolonged period of decreased human occupation has been proposed for Mendoza Province, provoked by conditions of increasing aridity during the mid-Holocene. It has also been suggested that the systematic human peopling of the high-altitude Andean environments started ca. 2000-1500 years BP, because of a process of economic intensification in lowland areas with higher availability of resources. In this paper, we present the results of a project designed to assess the role of volcanic activity and glacial advances as the main cause for archaeological discontinuities recorded in the archaeological record of the high Andes. This study covers a latitudinal range between 35 degrees-37 degrees S. We present geochemical and chronological results for tephras recorded in archaeological and geological sites, attempting to define the volcanic sources and their impact on the landscape. The analysis includes a geoarchaeological study of the Valenzuela River, which shows the magnitude of the volcanic activity in the Planchon-Peteroa complex, as well as the extent of Holocene glacial processes. The results presented allow suggesting alternative explanation for the temporal sequences of the archaeological record, inasmuch as highlighting the contribution of geoarchaeology.
Monteoliva, JM ;Villalba, A ; Acena, A ; Pattini, A ; REVISTA HABITAT SUSTENTABLE ,2016 ,6 ,51 -59 .
One of the most efficient ways to reduce the energy consumption of artificial lighting is through the proper use of daylight in indoor spaces. However, current regulations governing the use of daylight in indoor spaces are outdated and in some cases are not easy to apply. Thus, designers are not encouraged to seek energy efficient solutions that enhance the use of daylight to illuminate interior spaces during daytime hours. This paper proposes a simplified model for calculating the useful daylight illuminance (UDI) for individual perimeter rooms under clear skies. This model seeks to combine the precision and validity of dynamic simulations in the study of daylight, in a simple and appropriate prediction tool for professionals in real environments.
Escudero, LB ;Maniero, MA ; Agostini, E ; Smichowski, PN ; TRAC-TRENDS IN ANALYTICAL CHEMISTRY ,2016 ,80 ,531 -546 .
Biological substrates have been introduced in Analytical Chemistry to encourage the development of environment-friendly methodologies. This kind of substrates offers advantages such as low cost, very simple production and biodegradability. Moreover, they are considered highly efficient materials for extraction and separation of elemental species.
Osimani, VLR ;Valdez, SR ; Guinazu, N ; Magnarelli, G ; REPRODUCTIVE TOXICOLOGY ,2016 ,61 ,47 -57 .
The impact of environmental organophosphate (OP) pesticide exposure on respiratory complexes, enzymatic antioxidant defense activities, and oxidative damage markers in the syncytiotrophoblast and cytotrophoblast mitochondria was evaluated. Placenta] progesterone (PG) levels and endothelia] nitric oxide synthase (eNOS) expression were studied. Samples from women non-exposed (control group-CG) and women living in a rural area (rural group-RG) were collected during pesticide spraying season (RG-SS) and non-spraying season (RG-NSS).
Metcalf, JL ;Turney, C ; Barnett, R ; Martin, F ; Bray, SC ; Vilstrup, JT ; Orlando, L ; Salas-Gismondi, R ; Loponte, D ; Medina, M ; De Nigris, M ; Civalero, T ; Fernandez, PM ; Gasco, A ; Duran, V ; Seymour, KL ; Otaola, C ; Gil, A ; Paunero, R ; Prevosti, FJ ; Bradshaw, CJA ; Wheeler, JC ; Borrero, L ; Austin, JJ ; Cooper, A ; SCIENCE ADVANCES ,2016 ,2 ,-.
The causes of Late Pleistocene megafaunal extinctions (60,000 to 11,650 years ago, hereafter 60 to 11.65 ka) remain contentious, with major phases coinciding with both human arrival and climate change around the world. The Americas provide a unique opportunity to disentangle these factors as human colonization took place over a narrow time frame (similar to 15 to 14.6 ka) but during contrasting temperature trends across each continent. Unfortunately, limited data sets in South America have so far precluded detailed comparison. We analyze genetic and radiocarbon data from 89 and 71 Patagonian megafaunal bones, respectively, more than doubling the high-quality Pleistocene megafaunal radiocarbon data sets from the region. We identify a narrow megafaunal extinction phase 12,280 +/- 110 years ago, some 1 to 3 thousand years after initial human presence in the area. Although humans arrived immediately prior to a cold phase, the Antarctic Cold Reversal stadial, megafaunal extinctions did not occur until the stadial finished and the subsequent warming phase commenced some 1 to 3 thousand years later. The increased resolution provided by the Patagonian material reveals that the sequence of climate and extinction events in North and South America were temporally inverted, but in both cases, megafaunal extinctions did not occur until human presence and climate warming coincided. Overall, metapopulation processes involving subpopulation connectivity on a continental scale appear to have been critical for megafaunal species survival of both climate change and human impacts.
Aschero, V ;Morris, WF ; Vazquez, DP ; Alvarez, JA ; Villagra, PE ; FOREST ECOLOGY AND MANAGEMENT ,2016 ,369 ,184 -190 .
One of the most important current challenges for ecologists is to evaluate how human-induced changes in ecosystems would impact viability of populations. Demographic response to anthropogenic impact could help us to understand how to manage those impacts. Using demographic techniques and population projection models, here we assess if demography and population dynamics of the tree Prosopis flexuosa change in cattle grazed areas compared to ungrazed areas in the Central Monte desert, Mendoza, Argentina. To this end, we quantified vital rates and constructed a population projection matrix model to compare the deterministic population growth rate (lambda) between grazed and ungrazed areas. We also estimated elasticities of vital rates to evaluate their potential importance for future changes in lambda and performed a life table response experiment (LTRE) to identify the life cycle transitions that contribute the most to the observed differences in lambda between the two treatments. Although we found differences in demographic processes, such as lower seed production and higher probability of reversion to smaller size classes in young individuals when cattle were present, our results indicate that cattle grazing had no significant effect on lambda for this species. According to the elasticity analysis, survival of large trees is the main driver of the population growth rate (lambda) of P. flexuosa, and the vital rates related to tree reproduction, such as seed production and germination, have a poor contribution to lambda. Therefore, limitations of activities that can affect survival of large trees should be considered as part of the conservation strategy for this species. Our study provides a compilation of demographic information that can be useful to set policies connecting the conservation objectives for this woodlands with that of ranch managers of the area. (C) 2016 Published by Elsevier B.V.
Martinez-Asencio, J ;Ruestes, CJ ; Bringa, EM ; Caturla, MJ ; PHYSICAL CHEMISTRY CHEMICAL PHYSICS ,2016 ,18 ,13897 -13903 .
Ripples present in free standing graphene have an important influence on the mechanical behavior of this two-dimensional material. In this study, we show through nanoindentation simulations, how out-of-plane displacements can be modified by strain, resulting in softening of the membrane under compression and stiffening under tension. Irradiation also induces changes in the mechanical properties of graphene. Interestingly, compressed samples, irradiated at low doses are stiffened by the irradiation, whereas the samples under tensile strain do not show significant changes in their mechanical properties. These simulations indicate that vacancies produced by the energetic ions cannot be the ones directly responsible for this behavior. However, changes in roughness induced by the momentum transferred from the energetic ions to the membrane, can explain these differences. These results provide an alternative explanation to recent experimental observations of the stiffening of graphene under low dose irradiation, as well as the paths to tailor the mechanical properties of this material via applied strain and irradiation.
Marsh, EJ ;CAMBRIDGE ARCHAEOLOGICAL JOURNAL ,2016 ,26 ,305 -327 .
A community is an active assemblage of human and non-human elements bound together by interactions. Archaeologies of communities shed light on sets of overlapping and geographically emplaced assemblages of individuals, practices, spaces, buildings, objects, animals and landscapes. This article presents an archaeology of communities based a remarkably well preserved Late Formative (ad 1-500) patio group at Khonkho Wankane, Bolivia. Excavation data provide a high-resolution chronology and document two varieties of assemblages: (1) those that played a greater role in biologically and socially reproducing the community, such as daily food and tool production; and (2) those that played a greater role in its transformation, such as gatherings, work parties and construction projects. In the patio group, intimate meetings took place in small, private spaces where incense was burned. Larger gatherings took place in an outdoor space where painted Kalasasaya small jars and bowls were active elements in interactions between residents and visitors. These events most likely involved work parties that contributed to the physical and social construction of the community. Assemblages at multiple scales built a diverse Late Formative community, which played a principal role in regional interaction networks. Within a few generations of residents leaving their homes in Khonkho, local and regional interactions generated the emergence of a state at Tiwanaku.
Ruestes, CJ ;Farkas, D ; Caro, A ; Bringa, EM ; ACTA MATERIALIA ,2016 ,108 ,1 -7 .
We report the results of compressive tests for a model bi-continuous nanoporous gold structure using atomistic simulations focusing on the densification regime and the plasticity mechanisms taking place. The stress - strain response follows a logarithmic evolution proportional to the inverse of strain and we provide a simple scaling law for this behavior. Hardening is correlated to the dislocation density and an exponential dependence is revealed. The plasticity mechanisms were inspected revealing the presence of Hirth and Frank partials contributing to the hardening of the sample. Lomer-Cottrel locks, perfect dislocations, and twinning were also found. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
So, KP ;Chen, D ; Kushima, A ; Li, MD ; Kim, S ; Yang, Y ; Wang, ZG ; Park, JG ; Lee, YH ; Gonzalez, RI ; Kiwi, M ; Bringa, EM ; Shao, L ; Li, J ; NANO ENERGY ,2016 ,22 ,319 -327 .
We can mass-produce metal/carbon nanotube (CNT) composites that show improved radiation tolerance. The 0.5 wt% Al+CNT composite showed improved tensile strength without reduction of tensile ductility before radiation, and reduced void/pore generation and radiation embrittlement at high displacements per atom (DPA). Under helium ion irradiation up to 72 DPA, the 1D carbon nanostructures survive, while sp(2) bonded graphene transforms to spa tetrahedral amorphous carbon. Self-ion (Al) irradiation converts CNTs to a metastable form of Al4C3, but still as slender 1D nanorods with prolific internal interfaces that catalyze recombination of radiation defects, reducing radiation hardening and porosity generation. The 1D fillers may also form percolating paths of "nano-chimneys" that outgas the accumulated helium and other fission gases, providing an essential solution to the gas accumulation problem. (C) 2016 Elsevier Ltd. All rights reserved.
Saiz-Lopez, A ;Fernandez, RP ; GEOPHYSICAL RESEARCH LETTERS ,2016 ,43 ,2928 -2935 .
Halogens produced by ocean biological and photochemical processes reach the tropical tropopause layer (TTL), where cold temperatures and the prevailing low ozone abundances favor the diurnal photochemical enhancement of halogen atoms. Under these conditions atomic bromine and iodine are modeled to be the dominant inorganic halogen species in the sunlit TTL, surpassing the abundance of the commonly targeted IO and BrO radicals. We suggest that due to the rapid photochemical equilibrium between halogen oxides and halogen atoms a natural atmospheric phenomenon evolves, which we have collectively termed tropical rings of atomic halogens. We describe the main causes controlling the modeled appearance and variability of these superposed rings of bare bromine and iodine atoms that circle the tropics following the Sun. Some potential implications for atmospheric oxidizing capacity are also explored. Our model results suggest that if experimentally confirmed, the extent and intensity of the halogen rings would directly respond to changes in oceanic halocarbon emissions, their atmospheric transport, and photochemistry.
Anders, C ;Bringa, EM ; Urbassek, HM ; APPLIED PHYSICS LETTERS ,2016 ,108 ,-.
Impact of energetic nanoparticles on solids produces craters on the surface. We use molecular dynamics simulations to compare crater production on a compact Au solid with that in a porous (foam) target. Our results show a complex picture: (i) At low impact velocities, the nanoparticles produce permanent craters in the foam while they cannot penetrate the compact target. (ii) With increasing velocity and/or projectile mass, the crater depth in the foam target increases less strongly than for the compact target. The plasticity-affected zone in the foam target is of similar size as in the compact target. Our results are relevant for the use of porous structures as shields against nanoparticle impact. (C) 2016 AIP Publishing LLC.
Camin, SR ;Martin-Albarracin, V ; Jefferies, M ; Marone, L ; JOURNAL OF AVIAN BIOLOGY ,2016 ,47 ,245 -251 .
The neophobia threshold hypothesis (NTH) suggests that the acquisition and maintenance of a high behavioral and ecological flexibility in the evolutionary and adaptive history of a species is the consequence of lower levels of neophobia towards new micro-habitats and of dietary wariness of novel foods. To test this idea we assessed the degree of neophobia and dietary wariness in two seed-eating bird species with contrasting degrees of ecological flexibility that inhabit the central Monte desert (Argentina): a grass-seed specialist, the many-colored chaco-finch, and a generalist feeder, the rufous-collared sparrow. We expected that both species would exhibit neophobia and wariness when faced with new foraging opportunities but that the rufous-collared sparrow would be less neophobic and less wary than the specialized many-colored chaco-finch. Experimental indicators of neophobia and dietary wariness included willingness to eat near novel objects and willingness to eat novel seeds, respectively. Both species showed similar levels of reluctance to novelty, although the sparrow could be slightly more reluctant than the finch. Contrary to our predictions, the sparrow was neither less hesitant nor faster or greedier than the finch. This experimental evidence does not support a negative relationship between neophobia/wariness and ecological flexibility in these two seed-eating birds and it coincides with the growing evidence that challenges the NTH. Some of our results provide support for the dangerous niche hypothesis, especially as the rufous-collared sparrow, that feeds on more diverse and potentially dangerous food, showed higher levels of neophobia in some cases. Although the idea of neophobia and wariness being plausible causes of ecological specialization sounds attractive, the current situation calls for further research so that the causes of ecological flexibility in granivorous birds can be better understood.
Millan, EN ;Goiran, SB ; Piccoli, MF ; Garino, CG ; Aranibar, JN ; Bringa, EM ; CLUSTER COMPUTING-THE JOURNAL OF NETWORKS SOFTWARE TOOLS AND ,2016 ,19 ,557 -566 .
Recently, a Monte Carlo model was proposed in order to simulate settlement dynamics in drylands, including several environmental factors, and it was implemented as a serial CPU code. In this work we present a parallel implementation of that code using graphics processing units (GPU) and NVIDIA CUDA. The code was tested with two experiments, a Baseline case and a Realistic case. We take advantage of the GPU architecture to obtain significant speedups: 8 to 20 with the Baseline case in a NVIDIA Tesla C2050 versus a Phenom 1055T CPU. The Realistic case obtained 80 of speedup in the same hardware. The GPU performance of the code will allow the inclusion of additional factors affecting settlements and large grid sizes for detailed environmental degradation models.
Millan, EN ;Tramontina, DR ; Urbassek, HM ; Bringa, EM ; PHYSICAL CHEMISTRY CHEMICAL PHYSICS ,2016 ,18 ,3423 -3429 .
When nanoparticles (NPs) collide with low velocities, they interact elastically in the sense that - besides their fusion caused by their mutual van-der-Waals attraction - no defects are generated. We investigate the minimum velocity, v(c), necessary for generating defects and inducing plasticity in the NP. The determination of this elastic-plastic threshold is of prime importance for modeling the behavior of granular matter. Using the generic Lennard-Jones interaction potential, we find v(c) to increase strongly with decreasing radius. Current models do not agree with our simulations, but we provide a model based on dislocation emission in the contact zone that quantitatively describes the size dependence of the elastic-plastic transition.
Alhafez, IA ;Ruestes, CJ ; Gao, Y ; Urbassek, HM ; NANOTECHNOLOGY ,2016 ,27 ,-.
Using molecular dynamics simulation, we study the nanoindentation of three hcp metals: Mg, Ti, and Zr. Both the basal and two prismatic surface planes are considered. We focus on the characterization of the plasticity generated in the crystal. The similarities to, and the differences from, the behavior of the more commonly investigated fcc and bcc metals are highlighted. We find that hcp metals show a larger variety than the fcc and bcc metals studied up until now. The prolific emission of prismatic loops can lead to extended plastic zones. The size of the plastic zone is quantified by the ratio f of the plastic zone radius to the radius of the contact area. We find values of between 1.6 (an almost collapsed zone) and > 5; in the latter case, complex dislocation networks build up which are extended in the direction of easy glide.
Berton, P ;Lana, NB ; Rios, JM ; Garcia-Reyes, JF ; Altamirano, JC ; ANALYTICA CHIMICA ACTA ,2016 ,905 ,24 -41 .
Green chemistry principles for developing methodologies have gained attention in analytical chemistry in recent decades. A growing number of analytical techniques have been proposed for determination of organic persistent pollutants in environmental and biological samples. In this light, the current review aims to present state-of-the-art sample preparation approaches based on green analytical principles proposed for the determination of polybrominated diphenyl ethers (PBDEs) and metabolites (OH-PBDEs and MeO-PBDEs) in environmental and biological samples. Approaches to lower the solvent consumption and accelerate the extraction, such as pressurized liquid extraction, microwave-assisted extraction, and ultrasound-assisted extraction, are discussed in this review. Special attention is paid to miniaturized sample preparation methodologies and strategies proposed to reduce organic solvent consumption. Additionally, extraction techniques based on alternative solvents (surfactants, supercritical fluids, or ionic liquids) are also commented in this work, even though these are scarcely used for determination of PBDEs. In addition to liquid-based extraction techniques, solid-based analytical techniques are also addressed. The development of greener, faster and simpler sample preparation approaches has increased in recent years (2003e2013). Among green extraction techniques, those based on the liquid phase predominate over those based on the solid phase (71% vs. 29%, respectively). For solid samples, solvent assisted extraction techniques are preferred for leaching of PBDEs, and liquid phase microextraction techniques are mostly used for liquid samples. Likewise, green characteristics of the instrumental analysis used after the extraction and clean-up steps are briefly discussed. (C) 2015 Elsevier B.V. All rights reserved.
Riga, BJG ;Lamanna, MC ; David, LDO ; Calvo, JO ; Coria, JP ; SCIENTIFIC REPORTS ,2016 ,6 ,-.
Titanosauria is an exceptionally diverse, globally-distributed clade of sauropod dinosaurs that includes the largest known land animals. Knowledge of titanosaurian pedal structure is critical to understanding the stance and locomotion of these enormous herbivores and, by extension, gigantic terrestrial vertebrates as a whole. However, completely preserved pedes are extremely rare among Titanosauria, especially as regards the truly giant members of the group. Here we describe Notocolossus gonzalezparejasi gen. et sp. nov. from the Upper Cretaceous of Mendoza Province, Argentina. With a powerfully-constructed humerus 1.76 m in length, Notocolossus is one of the largest known dinosaurs. Furthermore, the complete pes of the new taxon exhibits a strikingly compact, homogeneous metatarsus-seemingly adapted for bearing extraordinary weight-and truncated unguals, morphologies that are otherwise unknown in Sauropoda. The pes underwent a near-progressive reduction in the number of phalanges along the line to derived titanosaurs, eventually resulting in the reduced hind foot of these sauropods.
Zhao, S ;Hahn, EN ; Kad, B ; Remington, BA ; Wehrenberg, CE ; Bringa, EM ; Meyers, MA ; ACTA MATERIALIA ,2016 ,103 ,519 -533 .
High-power, short-duration, laser-driven, shock compression and recovery experiments on  silicon unveiled remarkable structural changes above a pressure threshold. Two distinct amorphous regions were identified: (a) a bulk amorphous layer close to the surface and (b) amorphous bands initially aligned with (111) slip planes. Further increase of the laser energy leads to the re-crystallization of amorphous silicon into nanocrystals with high concentration of nano-twins. This amorphization is produced by the combined effect of high magnitude hydrostatic and shear stresses under dynamic shock compression. Shockinduced defects play a very important role in the onset of amorphization. Calculations of the free energy changes with pressure and shear, using the Patel-Cohen methodology, are in agreement with the experimental results. Molecular dynamics simulation corroborates the amorphization, showing that it is initiated by the nucleation and propagation of partial dislocations. The nucleation of amorphization is analyzed qualitatively by classical nucleation theory.
Arbocco, FCV ;Sasso, CV ; Actis, EA ; Caron, RW ; Hapon, MB ; Jahn, GA ; MOLECULAR AND CELLULAR ENDOCRINOLOGY ,2016 ,419 ,18 -28 .
Thyroid diseases have deleterious effects on lactation, litter growth and survival, and hinder the suckling induced hormone release, leading in the case of hyperthyroidism, to premature mammary involution. To determine the effects of hypothyroidism (HypoT) on late lactation, we analyzed the effect of chronic 6-propyl-2-thiouracil (PTU)-induced HypoT on mammary histology and the expression of members of the JAK/STAT/SOCS signaling pathway, milk proteins, prolactin (PRLR), estrogen (ER), progesterone (PR) and thyroid hormone (TR) receptors, markers of involution (such as stat3, lif, bcl2, BAX and PARP) on lactation (L) day 21. HypoT mothers showed increased histological markers of involution compared with control rats, such as adipose/epithelial ratio, inactive alveoli, picnotic nuclei and numerous detached apoptotic cells within the alveolar lumina. We also found decreased PRLR, 13-casein and alpha-lactoalbumin mRNAs, but increased SOCS1, SOCS3, STAT3 and LIF mRNAs, suggesting a decrease in PRL signaling and induction of involution markers. Furthermore, Caspase-3 and 8 and PARP labeled cells and the expression of structural proteins such as beta-Actin, alpha-Tubulin and Lamin B were increased, indicating the activation of apoptotic pathways and tissue remodelation. HypoT also increased PRA (mRNA and protein) and er,6 and decreased era mRNAs, and increased strongly TR alpha 1, TR beta 1, PRA and ER alpha protein levels. These results show that lactating HypoT rats have premature mammary involution, most probably induced by the inhibition of prolactin signaling along with the activation of the LIF-STAT3 pathway. (C) 2015 Elsevier Ireland Ltd. All rights reserved.
Zodrow, EL ;D'Angelo, JA ; Cleal, CJ ; BULLETIN OF GEOSCIENCES ,2016 ,91 ,669 -704 .
The primary study material consists of the 65-cm frond Neuropteris ovata (Hoffmann) var. simonii, associate petiole with organically attached cyclopteroid leaflets and trunk. Ancillary N. ovata material is used, all from the Asturian-Cantabrian strata of the Sydney Coalfield, Canada. This material is appropriate for the objective of the study to present an ovata-frond Aufbau in terms of micromorphology coupled with chemistry using an holistic sampling design (co-ordinating epidermal microscopy with chemistry per sample location). Chemical analyses were obtained by the reliable FTIR technique (Fourier transform infrared spectroscopy) and interpreted via chemometrics by methods of principal component analysis. Fractal geometry is introduced as a promising taxonomic parameter. The main conclusions include that the N. ovata plant can be characterized by three distinct epidermal structures: (1) rectangular elongate (trunk and petiole), (2) elongate (rachides of three orders), and (3) undulate (pinnule), which to a certain extent agrees with the chemistry of the frond Aufbau. The frond was also complex - architecturally, histologically, physiologically, chemically and autecologically. It was photosynthetic, had secretory organs (implying a characteristic plant aroma), supporting rodlets, divers epicuticular features, and a distinct chemical composition/structure. The frond was likely 4 m long with complex-pinnate cyclopteroid leaflets, fimbriate or entire-margined, below and above the main bifurcation, which begs the question of cyclopteroid definition and function. The overall results will be beneficial to taxonomy/systematics, and guide pteridospermous reconstruction into a new paradigm.
Erquiaga, MJ ;Catania, C ; Garcia, S ; 2016 IEEE BIENNIAL CONGRESS OF ARGENTINA (ARGENCON) ,2016 ,,-.
Some botnets use special algorithms to generate the domain names they need to connect to their command and control servers. They are refereed as Domain Generation Algorithms. Domain Generation Algorithms generate domain names and tries to resolve their IP addresses. If the domain has an IP address, it is used to connect to that command and control server. Otherwise, the DGA generates a new domain and keeps trying to connect. In both cases it is possible to capture and analyze the special behavior shown by those DNS packets in the network. The behavior of Domain Generation Algorithms is difficult to automatically detect because each domain is usually randomly generated and therefore unpredictable. Hence, it is challenging to separate the DNS traffic generated by malware from the DNS traffic generated by normal computers. In this work we analyze the use of behavioral detection approaches based on Markov Models to differentiate Domain Generation Algorithms traffic from normal DNS traffic. The evaluation methodology of our detection models has focused on a real-time approach based on the use of time windows for reporting the alerts. All the detection models have shown a clear differentiation between normal and malicious DNS traffic and most have also shown a good detection rate. We believe this work is a further step in using behavioral models for network detection and we hope to facilitate the development of more general and better behavioral detection methods of malware traffic.
Pacini, E ;Mateos, C ; Garino, CG ; 2016 IEEE BIENNIAL CONGRESS OF ARGENTINA (ARGENCON) ,2016 ,,-.
Federated Clouds are infrastructures arranging physical resources from different datacenters. A Cloud broker intermediates between users and datacenters to support the execution of jobs through Virtual Machines (VM). We exploit federated Clouds to run CPU-intensive jobs, in particular, Parameter Sweep Experiments (PSE). Specifically, we study a broker-level scheduler based on Ant Colony Optimization (ACO), which aims to select the datacenters taking into account both the network latencies and the availability of resources. The less the network latency, the lower the influence on makespan. Moreover, when more VMs can be allocated in datacenters with lower latency, more physical resources can be taken advantage of, and hence job execution time decreases. Then, once our broker-level scheduler has selected a datacenter to execute jobs, VMs are allocated in the physical machines of that datacenter by another intra-datacenter scheduler based on ACO. Experiments performed using CloudSim and job data from a real PSE show that our ACO-based broker-level scheduler succeeds in reducing the makespan compared to similar schedulers based on latency-aware greedy and round robin heuristics.
Aguilera, AC ;Carvelli, L ; Boschin, V ; Mohamed, F ; Zyla, L ; Sosa, MA ; REPRODUCTION FERTILITY AND DEVELOPMENT ,2016 ,28 ,1608 -1617 .
One of the most striking features of the mammalian epididymis is the secretion of lysosomal enzymes (LE). These LE may play a role in sperm maturation. In the present study we investigated the activity and distribution of four LE (-galactosidase (-Gal), N-acetyl--D-glucosaminidase (-NAG), -mannosidase (-Man) and -glucuronidase (-Glu)) in bull epididymis at two different ages (6 months and 4 years) to determine whether these enzymes vary with sexual maturity. In young, sexually immature (SI) bulls we found high LE activity in the epididymal tissue that accounts for a developed and active lysosomal apparatus. In contrast, low LE activity was measured in sexually mature (SM) bulls, and -NAG and -Gal were mostly secreted into the lumen. We also attempted to correlate LE distribution with the expression and functionality of mannose-6-phosphate receptors (MPRs), which are thought to be involved in proper delivery of LE to lysosomes. The cation-dependent MPR was highly expressed in SI bulls, with expression decreasing during adulthood, whereas the expression of the cation-independent MPR was higher in SM than SI bulls. In addition, the four enzymes recovered from the epididymal lumen interact with both MPRs at each age. We conclude that the activity and distribution of LE in bull epididymis varies with sexual maturity and that the distribution is regulated differently by the two types of MPR. These findings could provide some molecular basis for male infertility.
Pacini, E ;Mateos, C ; Garino, CG ; Careglio, C ; Mirasso, A ; JOURNAL OF INTELLIGENT & FUZZY SYSTEMS ,2016 ,31 ,1731 -1743 .
Computational Mechanics (CM) concerns the use of computational methods to study phenomena under the principles of mechanics. A representative CM application is parameter sweep experiments (PSEs), which involves the execution of many CPU-intensive jobs and thus computing environments such as Clouds must be used. We focus on federated Clouds, where PSEs are processed via virtual machines (VM) that are lauched in hosts belonging to different datacenters, minimizing both the makespan and flowtime. Scheduling is performed at three levels: a) broker, where datacenters are selected based on their network latencies via three policies, b) infrastructure, where two bio-inspired schedulers based on Ant Colony Optimization (ACO) and Particle Swarm Optimization (PSO) for VM-host mapping in a datacenter are implemented, and c) VM, where jobs are assigned into the preallocated VMs based on job priorities. Simulated experiments performed with job data from two real PSEs show that our scheduling approach allows for a more agile job handling while reducing PSE makespan and flowtime.
Neme, G ;Sugranes, N ; Salgan, L ; Gil, A ; Otaola, C ; Giardina, M ; Morgan, C ; Llano, C ; RELACIONES ,2016 ,41 ,101 -130 .
This paper presents the results of fieldwork at Risco de los Indios, an archaeological site situated at 2.400 m elevation in the upper Diamante River watershed. The site contains twenty nine stacked-rock residential structures and dates to ca. 500 cal BP. Recovered faunal and macrobotanical remains indicate the site focused mainly on hunting camelids, underwritten by exploitation of local plants as well as transport and consumption of domestic beans (Phaseolus vulgaris). Extralocal ceramics and obsidian sourcing indicates substantial mobility and contact with other groups within and across the southern Andes. These results are discussed in the context of the other high-altitude residential sites in the southern Mendoza region.
D'Angelo, JA ;Zodrow, EL ; INTERNATIONAL JOURNAL OF COAL GEOLOGY ,2016 ,153 ,12 -27 .
The largest known 65-cm frond segment of Neuropteris ovata var. simonii (Order: Medullosales) from the Late Pennsylvanian of Sydney Coalfield, Canada, is preserved as compression and naturally macerated cuticle and comprises the study sample. The study objectives included (i) analyzing the chemical variability throughout the frond, (ii) interpreting chemical differences in the lower from the upper part of the frond (impossible to do from fragmented specimens), (iii) inferring the likely biopolymeric make-up of the tissues of the once-living plant, (iv) estimating the likely metabolic cost of plant tissue production, and (v) suggesting autecological aspects.
Rodriguez, MH ;Rosales, GD ; Pinna, EG ; Suarez, DS ; HYDROMETALLURGY ,2016 ,159 ,60 -64 .
The effect of different leaching media on the dissolution of ferrocolumbite from the province of San Luis, Argentina, in an autoclave was investigated. The leaching agents used were aqueous solutions of HF-NaF or HF-Na2C2O4.
Fort, H ;Vazquez, DP ; Lan, BL ; ECOLOGY LETTERS ,2016 ,19 ,4 -11 .
A frequent observation in plant-animal mutualistic networks is that abundant species tend to be more generalised, interacting with a broader range of interaction partners than rare species. Uncovering the causal relationship between abundance and generalisation has been hindered by a chicken-and-egg dilemma: is generalisation a by-product of being abundant, or does high abundance result from generalisation? Here, we analyse a database of plant-pollinator and plant-seed disperser networks, and provide strong evidence that the causal link between abundance and generalisation is uni-directional. Specifically, species appear to be generalists because they are more abundant, but the converse, that is that species become more abundant because they are generalists, is not supported by our analysis. Furthermore, null model analyses suggest that abundant species interact with many other species simply because they are more likely to encounter potential interaction partners.
Ottina, M ;TOPOLOGY AND ITS APPLICATIONS ,2016 ,197 ,60 -74 .
We develop a cofibrantly generated model category structure in the category of topological spaces in which weak equivalences are A-weak equivalences and such that the generalized CW(A)-complexes are cofibrant objects. With this structure the exponential law turns out to be a Quillen adjunction. (C) 2015 Elsevier B.V. All rights reserved.
Anderson, DC ;Nicely, JM ; Salawitch, RJ ; Canty, TP ; Dickerson, RR ; Hanisco, TF ; Wolfe, GM ; Apel, EC ; Atlas, E ; Bannan, T ; Bauguitte, S ; Blake, NJ ; Bresch, JF ; Campos, TL ; Carpenter, LJ ; Cohen, MD ; Evans, M ; Fernandez, RP ; Kahn, BH ; Kinnison, DE ; Hall, SR ; Harris, NRP ; Hornbrook, RS ; Lamarque, JF ; Le Breton, M ; Lee, JD ; Percival, C ; Pfister, L ; Pierce, RB ; Riemer, DD ; Saiz-Lopez, A ; Stunder, BJB ; Thompson, AM ; Ullmann, K ; Vaughan, A ; Weinheimer, AJ ; NATURE COMMUNICATIONS ,2016 ,7 ,-.
Air parcels with mixing ratios of high O-3 and low H2O (HOLW) are common features in the tropical western Pacific (TWP) mid-troposphere (300-700 hPa). Here, using data collected during aircraft sampling of the TWP in winter 2014, we find strong, positive correlations of O-3 with multiple biomass burning tracers in these HOLW structures. Ozone levels in these structures are about a factor of three larger than background. Models, satellite data and aircraft observations are used to show fires in tropical Africa and Southeast Asia are the dominant source of high O-3 and that low H2O results from large-scale descent within the tropical troposphere. Previous explanations that attribute HOLW structures to transport from the stratosphere or mid-latitude troposphere are inconsistent with our observations. This study suggest a larger role for biomass burning in the radiative forcing of climate in the remote TWP than is commonly appreciated.
Monge, DA ;Holec, M ; Zelezny, F ; Garino, CG ; CLUSTER COMPUTING-THE JOURNAL OF NETWORKS SOFTWARE TOOLS AND ,2015 ,18 ,1317 -1329 .
The adequate management of scientific workflow applications strongly depends on the availability of accurate performance models of sub-tasks. Numerous approaches use machine learning to generate such models autonomously, thus alleviating the human effort associated to this process. However, these standalone models may lack robustness, leading to a decay on the quality of information provided to workflow systems on top. This paper presents a novel approach for learning ensemble prediction models of tasks runtime. The ensemble-learning method entitled bootstrap aggregating (bagging) is used to produce robust ensembles of M5P regression trees of better predictive performance than could be achieved by standalone models. Our approach has been tested on gene expression analysis workflows. The results show that the ensemble method leads to significant prediction-error reductions when compared with learned standalone models. This is the first initiative using ensemble learning for generating performance prediction models. These promising results encourage further research in this direction.
Saen-Oon, S ;de Vaca, IC ; Masone, D ; Medina, M ; Guallar, V ; BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS ,2015 ,1847 ,1530 -1538 .
In the photosynthetic electron transfer (ET) chain, two electrons transfer from photosystem I to the flavin-dependent ferredoxin-NADP reductase (FNR) via two sequential independent ferredoxin (Fd) electron carriers. In some algae and cyanobacteria (as Anabaena), under low iron conditions, flavodoxin (Fld) replaces Fd as single electron carrier. Extensive mutational studies have characterized the protein-protein interaction in FNR/Fd and FNR/Fld complexes. Interestingly, even though Fd and Fld share the interaction site on FNR, individual residues on FNR do not participate to the same extent in the interaction with each of the protein partners, pointing to different electron transfer mechanisms. Despite of extensive mutational studies, only FNR/Fd X-ray structures from Anabaena and maize have been solved; structural data for FNR/Fld remains elusive. Here, we present a multiscale modelling approach including coarse-grained and all-atom protein-protein docking, the QM/MM e-Pathway analysis and electronic coupling calculations, allowing for a molecular and electronic comprehensive analysis of the ET process in both complexes. Our results, consistent with experimental mutational data, reveal the ET in FNR/Fd proceeding through a bridge-mediated mechanism in a dominant protein-protein complex, where transfer of the electron is facilitated by Fd loop-residues 40-49. In FNR/Fld, however, we observe a direct transfer between redox cofactors and less complex specificity than in Fd; more than one orientation in the encounter complex can be efficient in ET. (C) 2015 Elsevier B.V. All rights reserved.
Zhao, S ;Kad, B ; Hahn, EN ; Remington, BA ; Wehrenberg, CE ; Huntington, CM ; Park, HS ; Bringa, EM ; More, KL ; Meyers, MA ; EXTREME MECHANICS LETTERS ,2015 ,5 ,74 -80 .
Here we report that high-power, pulsed, laser-driven shock compression of monocrystalline silicon produces directional amorphization, revealed by high-resolution transmission electron microscopy and confirmed by molecular dynamics simulations. At the lowest energy level experiment, generating a pressure of similar to 4 GPa, silicon reacts elastically. At intermediate energy levels (P similar to 11 and 22 GPa), amorphization is observed both at the surface and directionally, along planes making angles close to the maximum shear. At the highest laser energy level explored here, (P-peak similar to 28 GPa), the recovered sample shows a nanocrystalline microstructure near the surface. This nanocrystalline structure forms by crystallization from the amorphous phase and is thought to be a post-shock phenomenon. Shearinduced lattice defects (stacking faults and twins) on crystallographic slip planes play a crucial role in the onset of amorphization. Molecular dynamics show that silicon behaves elastically until similar to 10 GPa and, at slightly higher pressures, partial dislocations and stacking faults are emitted from the surface. Driven by the high-amplitude stress pulse, these defects travel inwards along specific crystallographic orientations and intersect, leading to further defect creation, additional plastic work, and, at higher pressures, amorphous bands in intersecting patterns. The typical high-pressure solid-solid phase transitions of silicon are not observed whereas the high shear stresses are relaxed by localized dislocation motion/interactions and eventually by directional amorphization, which occurs below the critical hydrostatic pressure for melting of silicon in shock compression. It is therefore proposed that the combined effects of hydrostatic and shear stresses lead to directional amorphization. (C) 2015 Elsevier Ltd. All rights reserved.
Marsh, EJ ;Schreiber, K ; JOURNAL OF ARCHAEOLOGICAL SCIENCE-REPORTS ,2015 ,4 ,54 -64 .
The Wari empire (AD 600-1000) deployed a variety of strategies to consolidate its provinces in Middle Horizon Peru. One strategy may have been building imperial sites in places with large visual magnitudes, which are attractive to empires because they are more defensible, they are suitably located for direct and implied surveillance, and they project a visually-dominant presence on the landscape. In the Sondondo Valley, Peru, the Wari empire made a significant investment of labor and resources in the construction of terraces, roads, and five imperial sites. The viewsheds of these sites are compared to those of 20 non-imperial sites, 495 randomly-placed individual sites, and 99 randomly-placed groups of five sites each. Parametric and non-parametric comparisons reject the null hypothesis that there is no difference between viewsheds. Imperial sites had significantly larger and better-coordinated viewsheds, as estimated from overlap and coverage indices. These results support-the argument that imperial agents' site-placement decisions considered the benefits of locations with large viewsheds. From these sites, the empire's representatives effectively advanced imperial goals for two and half centuries. Similar factors may have been salient in other imperial settings, so this approach may help explore site-placement decisions in other regions. (C) 2015 Elsevier Ltd. All rights reserved.
Figueroa, E ;Tramontina, D ; Gutierrez, G ; Bringa, E ; JOURNAL OF NUCLEAR MATERIALS ,2015 ,467 ,677 -682 .
In this work we study, by means of molecular dynamics simulation, the change in the mechanical properties of a gold nanowire with pre-existing radiation damage. The gold nanowire is used as a simple model for a nanofoam, made of connected nanowires. Radiation damage by keV ions leads to the formation of a stacking fault tetrahedron (SFT), and this defect leads to a reduced plastic threshold, as expected, when the nanowire is subjected to tension. We quantify dislocation and twin density during the deformation, and find that the early activation of the SFT as a dislocation source leads to reduced dislocation densities compared to the case without radiation damage. In addition, we observed a total destruction of the SFT, as opposed to a recent simulation study where it was postulated that SFTs might act as self-generating dislocation sources. The flow stress at large deformation is also found to be slightly larger for the irradiated case, in agreement with recent experiments. (C) 2015 Elsevier B.V. All rights reserved.
Ruestes, CJ ;Bringa, EM ; Rudd, RE ; Remington, BA ; Remington, TP ; Meyers, MA ; SCIENTIFIC REPORTS ,2015 ,5 ,-.
Plasticity is often controlled by dislocation motion, which was first measured for low pressure, low strain rate conditions decades ago. However, many applications require knowledge of dislocation motion at high stress conditions where the data are sparse, and come from indirect measurements dominated by the effect of dislocation density rather than velocity. Here we make predictions based on atomistic simulations that form the basis for a new approach to measure dislocation velocities directly at extreme conditions using three steps: create prismatic dislocation loops in a near-surface region using nanoindentation, drive the dislocations with a shockwave, and use electron microscopy to determine how far the dislocations moved and thus their velocity at extreme stress and strain rate conditions. We report on atomistic simulations of tantalum that make detailed predictions of dislocation flow, and find that the approach is feasible and can uncover an exciting range of phenomena, such as transonic dislocations and a novel form of loop stretching. The simulated configuration enables a new class of experiments to probe average dislocation velocity at very high applied shear stress.
Gunkelmann, N ;Bringa, EM ; Urbassek, HM ; JOURNAL OF APPLIED PHYSICS ,2015 ,118 ,-.
Intense shock waves may lead to spallation of the sample. Recent experiments show differences of shock spallation in iron depending on whether the samples underwent the pressure-induced bcchcp phase transformation or not. In this study, we perform molecular dynamics simulations of shock-induced spallation in polycrystalline iron. Our results show that the phase transformation decreases the probability of multiple spallation and crack formation. In agreement with experiments, the phase transformation changes the surface morphology showing smoother spallation surfaces. (C) 2015 AIP Publishing LLC.
Giri, N ;Del Popolo, MG ; Melaugh, G ; Greenaway, RL ; Ratzke, K ; Koschine, T ; Pison, L ; Gomes, MFC ; Cooper, AI ; James, SL ; NATURE ,2015 ,527 ,216 -+ .
Porous solids such as zeolites(1) and metal-organic frameworks(2,3) are useful in molecular separation and in catalysis, but their solid nature can impose limitations. For example, liquid solvents, rather than porous solids, are the most mature technology for post-combustion capture of carbon dioxide because liquid circulation systems are more easily retrofitted to existing plants. Solid porous adsorbents offer major benefits, such as lower energy penalties in adsorption-desorption cycles(4), but they are difficult to implement in conventional flow processes. Materials that combine the properties of fluidity and permanent porosity could therefore offer technological advantages, but permanent porosity is not associated with conventional liquids(5). Here we report free-flowing liquids whose bulk properties are determined by their permanent porosity. To achieve this, we designed cage molecules(6,7) that provide a well-defined pore space and that are highly soluble in solvents whose molecules are too large to enter the pores. The concentration of unoccupied cages can thus be around 500 times greater than in other molecular solutions that contain cavities(8-10), resulting in a marked change in bulk properties, such as an eightfold increase in the solubility of methane gas. Our results provide the basis for development of a new class of functional porous materials for chemical processes, and we present a one-step, multigram scale-up route for highly soluble 'scrambled' porous cages prepared from a mixture of commercially available reagents. The unifying design principle for these materials is the avoidance of functional groups that can penetrate into the molecular cage cavities.
Millan, EN ;Bederian, CS ; Piccoli, MF ; Garino, CG ; Bringa, EM ; COMPUTERS & ELECTRICAL ENGINEERING ,2015 ,48 ,12 -24 .
Cellular Automata (CA) are of interest in several research areas and there are many available serial implementations of CA. However, there are relatively few studies analyzing in detail High Performance Computing (HPC) implementations of CA which allow research on large systems. Here, we present a parallel implementation of a CA with distributed memory based on MPI. As a first step to insure fast performance, we study several possible serial implementations of the CA. The simulations are performed in three infrastructures, comparing two different microarchitectures. The parallel code is tested with both Strong and Weak scaling, and we obtain parallel efficiencies of similar to 75%-85%, for 64 cores, comparable to efficiencies for other mature parallel codes in similar architectures. We report communication time and multiple hardware counters, which reveal that performance losses are related to cache references with misses, branches and memory access. (C) 2015 Elsevier Ltd. All rights reserved.
Garcia, V ;Aranibar, J ; Pietrasiak, N ; ACTA OECOLOGICA-INTERNATIONAL JOURNAL OF ECOLOGY ,2015 ,69 ,35 -45 .
Biological soil crusts (BSC) play diverse roles in arid and semi-arid ecosystems such as increasing soil fertility and reducing soil loss due to aeolian and hydric erosion, but they are very sensitive to disturbances. These attributes point to the relevance of BSC for soil conservation and restoration. In order to use BSC for restoration of degraded soils, we need to understand the ecological drivers of BSC. In this study, we analyzed the effect of environmental factors on BSC cover at different spatial scales in the central Monte Desert (Argentina), including landform, slope, aspect, vascular plants, and disturbance intensity. We evaluated the effects of different factors with linear mixed effect models, comparing the adjustment of models of different complexity, which included different number of factors. First, at the landscape scale, we analyzed BSC cover in two geomorphological units with different soils, topography, and vegetation. BSC cover was higher in the old riverbed, which has a higher proportion of fine clay soil particles, than in the aeolian plain. Disturbance effects were apparent in the old riverbed, showing increasing BSC cover at higher distances from settlements, and BSC located both, under and outside plant canopies. At the mesoscale, we found no differences of BSC cover in dune flanks and inter-dune valleys of the aeolian plain. Finally, at the microscale, BSC patches of higher surface cover were found in association with vascular plants (Larrea divaricata, Bulnesia retama, Lycium sp.), on mounds, and in microsites of southern exposure and high slopes. Our findings suggest that BSC develop preferentially associated with vascular plants, which generate mounds and sloped microsites with southern exposure, where lower irradiances reduce desiccation in these extremely dry environments. (C) 2015 Elsevier Masson SAS. All rights reserved.
Gonzalez, C ;Panizo-Laiz, M ; Gordillo, N ; Guerrero, CL ; Tejado, E ; Munnik, F ; Piaggi, P ; Bringa, E ; Iglesias, R ; Perlado, JM ; Gonzalez-Arrabal, R ; NUCLEAR FUSION ,2015 ,55 ,-.
The trapping and mobility of hydrogen in nanostructured tungsten grain boundaries (GBs) have been studied by combining experimental and density functional theory (DFT) data. Experimental results show that nanostructured W coatings with a columnar grain structure and a large number of (1 1 0)/(2 1 1) interfaces retain more H than coarsed grained W samples. To investigate the possible influence of GBs on H retention, a complete energetic analysis of a non-coherent W(1 1 0)/ W(1 1 2) interface has been performed employing DFT. Our results show that this kind of non-coherent interface largely attracts point defects (both a H atom and a metallic monovacancy separately) and that the presence of these interfaces contributes to a decrease in the migration energy of the H atoms with respect to the bulk value. When both the W monovacancy and H atom are introduced together into the system, the HV complex becomes the most stable configuration and one of the mechanisms explaining the H retention in the radiation damaged GB observed experimentally.
Valencia, F ;Mella, JD ; Gonzalez, RI ; Kiwi, M ; Bringa, EM ; CARBON ,2015 ,93 ,458 -464 .
Swift heavy ion irradiation does not generate amorphous tracks in diamond, contrary to what happens in graphite or in diamond-like carbon. Since nanocrystalline diamond is of interest for several technological applications we investigate the reason for this difference, by means of large scale atomistic simulations of ion tracks in nanocrystalline diamond, using a thermal spike model, with up to 2.5 million atoms, and grain sizes in the range 5-10 nm. We conclude that tracking can be achieved under these conditions, when it is absent in single crystal diamond: for 5 nm samples the tracking threshold is below 15 keV/nm. Point defects are observed below this threshold. As the energy loss increases the track region becomes amorphous, and graphitic-like, with predominant sp(2) hybridization. This higher sensitivity to irradiation can be related to a very large decrease in thermal conductivity of nanocrystalline diamond, due to grain boundary confinement of the heat spike which enhances localized heating of the lattice. (C) 2015 Elsevier Ltd. All rights reserved.
Lu, CH ;Hahn, EN ; Remington, BA ; Maddox, BR ; Bringa, EM ; Meyers, MA ; SCIENTIFIC REPORTS ,2015 ,5 ,-.
The structural and mechanical response of metals is intimately connected to phase transformations. For instance, the product of a phase transformation (martensite) is responsible for the extraordinary range of strength and toughness of steel, making it a versatile and important structural material. Although abundant in metals and alloys, the discovery of new phase transformations is not currently a common event and often requires a mix of experimentation, predictive computations, and luck. High-energy pulsed lasers enable the exploration of extreme pressures and temperatures, where such discoveries may lie. The formation of a hexagonal (omega) phase was observed in recovered monocrystalline body-centered cubic tantalum of four crystallographic orientations subjected to an extreme regime of pressure, temperature, and strain-rate. This was accomplished using high-energy pulsed lasers. The omega phase and twinning were identified by transmission electron microscopy at 70 GPa (determined by a corresponding VISAR experiment). It is proposed that the shear stresses generated by the uniaxial strain state of shock compression play an essential role in the transformation. Molecular dynamics simulations show the transformation of small nodules from body-centered cubic to a hexagonal close-packed structure under the same stress state (pressure and shear).
Pacini, E ;Mateos, C ; Garino, CG ; IEEE LATIN AMERICA TRANSACTIONS ,2015 ,13 ,3359 -3369 .
For executing current simulated scientific experiments it is necessary to have huge amounts of computing power. A solution path to this problem is the federated Cloud model, where custom virtual machines (VM) are scheduled in appropriate hosts belonging to different providers to execute such experiments, minimizing response time. In this paper, we study schedulers for federated Clouds. Scheduling is performed at three levels. First, at the broker level, datacenters are selected by their network latencies via three policies - Lowest-Latency-Time-First, First-Latency-Time-First, and Latency-Time-In-Round-. Second, at the infrastructure level, two Cloud VM schedulers based on Ant Colony Optimization (ACO) and Particle Swarm Optimization (PSO) are implemented. At this level the scheduler is responsible for mapping VMs to datacenter hosts. Finally, at the VM level, jobs are assigned for execution into the pre-allocated VMs. We evaluate, through simulated experiments, how the proposed three-level scheduler performs w.r.t. the response time delivered to the user as the number of Cloud machines increases, a property known as horizontal scalability.
Arbocco, FCV ;Sasso, CV ; Nasif, DL ; Hapon, MB ; Jahn, GA ; MOLECULAR AND CELLULAR ENDOCRINOLOGY ,2015 ,412 ,26 -35 .
Thyroid hormones (TH) regulate mammary function. Hypothyroidism (HypoT) has deleterious effects on lactation, litter growth and survival. We analyzed the effect of chronic 6-propyl-2-thiouracil (PTU)-induced HypoT in the expression of nuclear receptors, co-regulators and oxytocin receptor (OTR) on lactation (L) days 2, 7 and 14. TH receptors (TRs) were increased on L7 at mRNA and protein levels, except TR alpha protein, that fell on L14. HypoT decreased TR alpha 2 mRNA on L7 and TR alpha 1 protein on L2, while TR beta 1 protein increased on L14. HypoT increased estrogen receptor beta (ER beta) mRNA on L7 but decreased its protein levels on L14. Progesterone receptor A (PRA) mRNA decreased from L2 to L14 while PRB increased, and at protein levels PRA levels showed a nadir on L7, while PRB peaked. HypoT decreased PRA mRNA and protein and increased PRB mRNA at L14. Nuclear receptor co-activator (NCOA) 1 and RXR alpha mRNA showed an opposite pattern to the TRs, while NCOA2 increased at L14; HypoT blocked the variations in NCOA1 and NCOA2. HypoT increased NCOR1 on L2 and decreased OTR at L2 and circulating estradiol and NCOR2 at L14. In controls the most notable changes occurred on L7, suggesting it is a key inflection point in mammary metabolism. The low levels of TR alpha 1, NCOA1 and OTR, and increased NCOR1 produced by HypoT on L2 may hinder the mammary ability to achieve normal milk synthesis and ejection, leading to defective lactation. Later on, altered ER and PR expression may impair further mammary function. (C) 2015 Elsevier Ireland Ltd. All rights reserved.
Monge, DA ;Holec, M ; Zelezny, F ; Garino, CG ; IEEE LATIN AMERICA TRANSACTIONS ,2015 ,13 ,3088 -3095 .
One of the central issues for the efficient management of Scientific workflow applications is the prediction of tasks performance. This paper proposes a novel approach for constructing performance models for tasks in data-intensive scientific workflows in an autonomous way. Ensemble Machine Learning techniques are used to produce robust combined models with high predictive accuracy. Information derived from workflow systems and the characteristics and provenance of the data are exploited to guarantee the accuracy of the models. A gene-expression analysis workflow application was used as case study over homogeneous and heterogeneous computing environments. Experimental results evidence noticeable improvements while using ensemble models in comparison with single/standalone prediction models. Ensemble learning techniques made it possible to reduce the prediction error with respect to the strategies of a single-model with values ranging from 14.47% to 28.36% for the homogeneous case, and from 8.34% to 17.18% for the heterogeneous case.
Ochoa, P ;COMMUNICATIONS ON PURE AND APPLIED ANALYSIS ,2015 ,14 ,1841 -1863 .
In this work, we propose and analyse approximation schemes for fully non-linear second order partial differential equations defined on the Heisenberg group. We prove that a consistent, stable and monotone scheme converges to a viscosity solution of a second order PDE on the Heisenberg group provided that comparison principles exists for the limiting equation. We also provide examples where this technique is applied.
Pol, RG ;Lopez de Casenave, J ; Milesi, FA ; MYRMECOLOGICAL NEWS ,2015 ,21 ,1 -12 .
Foraging strategy determines the way harvester ants use space and therefore their access and impact on seed resources. In this study, we described the foraging strategy of three sympatric South American species of Pogonomyrmex ants to confirm that they are solitary foragers as is suggested anecdotally in the literature. Then we tested whether those foraging strategies are fixed or flexible in response to seed density and distribution. Based on individual and group movements of foraging ants, we determined that P. rastratus MAYR, 1868 is exclusively a solitary foraging species, P. inermis FOREL, 1914 use a group-foraging strategy with limited recruitment, and P. mendozanus CUEZZO & CLAVER, 2009 displays an intermediate foraging system in which workers are typically solitary foragers but also recruit nestmates to high-density seed patches. The addition of seeds near the nest modified the foraging behavior of the three species by different amounts. Individual foragers of each species reduced their search time and search area, and colonies increased their foraging activity rate, probably as a result of a higher returning rate of successful foragers after seed addition. Such behavioral responses were much more conspicuous in P. mendozanus than in the other two species. Flexibility in foraging and diet breadth reported for some of these harvester ants may constitute important adaptive features in the central Monte desert where seed abundance is highly heterogeneous, irregular, and severely affected by anthropic disturbances.
Baldo, MN ;Hunzicker, GA ; Altamirano, JC ; Murguia, MC ; Hein, GJ ; INTERNATIONAL JOURNAL OF PHARMACEUTICAL SCIENCES AND RESEARCH ,2015 ,6 ,3752 -3760 .
The use of noninvasive biological samples such as saliva, it is of great interest for therapeutic drug monitoring (TDM), including the anticonvulsants Phenytoin (PHT). A simple analytical methodology by liquid chromatography-tandem mass spectrometry was developed and validated to carry out a relative comparative bioavailability (RBA) study of two PHT formulations in human plasma and saliva and the subsequent correlation between both matrixes. A single-dose, randomized-sequence, open-label, two-way crossover study, was conducted in 24 healthy Latin American male volunteers. The bioequivalence of 200 mg PHT tablet was evaluated using plasma and saliva to determine C-max, T-max, AUC(0-t) and AUC(0-infinity). Figures of merit of the proposed methodology were as follows: linear ranges of 40-5055 ng/mL and 5-1340 ng/mL for plasma and saliva, respectively, with a correlation coefficient of (r)>0.999. The LOD and LOQ were 15 ng/mL -40ng/mL for plasma and 1.5 ng/mL -5.0 ng/mL for saliva. Accuracy, precision (as % CV) and recovery were accepted according the bioequivalence criteria. Stability showed % bias<15%. The PHT saliva/PHT plasma ratios for all parameters were: 5.4, 2.2, 1.4 for C-max, and 1.7, 1.2, 1.1 for AUC. Plasma and saliva results were correlated (R=0.9889 and R=0.9947 for Reference and Test, respectively). Saliva not only is a suitable matrix for RBA studies and TDM, but also a more convenient tool since it provides analogous information with mayor analytical, ethical, and biosafety advantages. However, an additional pre-study of product dissolution in oral cavity is suggested before carrying out complete RBA studies for prompt-release drugs.
Barberena, R ;LATIN AMERICAN ANTIQUITY ,2015 ,26 ,304 -318 .
In this paper I present an intensively dated chrono-stratigraphic sequence for the Cueva Huenul 1 archaeological site, Neuquen Province, Argentina. Located in the inland deserts of northwestern Patagonia, Cueva Huenul 1 offers a remarkable temporal record of events for a largely unstudied desert region. I connect this local record with available data on a macro-regional scale to reassess (1) the timing of the first human colonization of the area and its implications for explaining the extinction of megafauna (ca. 14,000-10,000 cal B.P.) and (2) the decrease in human occupation recorded in several South American deserts during parts of the mid-Holocene (ca. 8000-6000 cal B.P.). The data presented here show a gap of about 1,500 calendar years between the extinction of megafauna and the appearance of humans. A review of evidence from the northern Patagonia and southern Cuyo regions is consistent with this record, favoring ecological causes for regional extinction of megafaunal taxa. Integration of this record with those indicating the earliest human presence in South America (e.g., Monte Verde, Chile) is consistent with a process of human radiation to the inland Patagonian deserts from nodes of initial occupation. The chrono-stratigraphic sequence from Cueva Huenul 1 also contributes to an assessment of a trough in human occupation along the South American Arid Diagonal around 8000-6000 cal B.P. Evidence for a decrease in occupational intensity during this period is found in the highland and lowland deserts in Mendoza and San Juan, the Puna region in northwestern Argentina, the Atacama Desert in Chile, and possibly the Pampean region. Previous researchers have suggested that persistent arid conditions would have produced increasing landscape fragmentation, particularly affecting desert areas. A more specific understanding of the demographic processes underlying this archaeological signal is needed. In this paper I suggest that this trough reflects not only spatial and social rearrangements, but also a macro-regional demographic retraction. This could have caused a population bottleneck with lasting biological and cultural implications.
Cuervo, PF ;Di Cataldo, S ; Fantozzi, MC ; Deis, E ; Isenrath, GD ; Viberti, G ; Artigas, P ; Peixoto, R ; Valero, MA ; Sierra, RMY ; Mas-Coma, S ; ACTA PARASITOLOGICA ,2015 ,60 ,536 -543 .
Fascioliasis has recently been included in the WHO list of Neglected Zoonotic Diseases. Besides being a major veterinary health problem, fascioliasis has large underdeveloping effects on the human communities affected. Though scarcely considered in fascioliasis epidemiology, it is well recognized that both native and introduced wildlife species may play a significant role as reservoirs of the disease. The objectives are to study the morphological characteristics of Fasciola hepatica adults and eggs in a population of Lepus europaeus, to assess liver fluke prevalence, and to analyze the potential reservoir role of the European brown hare in northern Patagonia, Argentina, where fascioliasis is endemic. Measures of F. hepatica found in L. europaeus from northern Patagonia demonstrate that the liver fluke is able to fully develop in wild hares and to shed normal eggs through their faeces. Egg shedding to the environment is close to the lower limit obtained for pigs, a domestic animal whose epidemiological importance in endemic areas has already been highlighted. The former, combined with the high prevalence found (14.28%), suggest an even more important role in the transmission cycle than previously considered. The results obtained do not only remark the extraordinary plasticity and adaptability of this trematode species to different host species, but also highlight the role of the European brown hare, and other NIS, as reservoirs capable for parasite spillback to domestic and native cycle, representing a potentially important, but hitherto neglected, cause of disease emergence.
de Paola, M ;Bello, OD ; Michaut, MA ; PLOS ONE ,2015 ,10 ,-.
Cortical granule exocytosis (CGE), also known as cortical reaction, is a calcium- regulated secretion that represents a membrane fusion process during meiotic cell division of oocytes. The molecular mechanism of membrane fusion during CGE is still poorly understood and is thought to be mediated by the SNARE pathway; nevertheless, it is unkown if SNAP (acronym for soluble NSF attachment protein) and NSF (acronym for N-ethilmaleimide sensitive factor), two key proteins in the SNARE pathway, mediate CGE in any oocyte model. In this paper, we documented the gene expression of alpha-SNAP, gamma-SNAP and NSF in mouse oocytes. Western blot analysis showed that the expression of these proteins maintains a similar level during oocyte maturation and early activation. Their localization was mainly observed at the cortical region of metaphase II oocytes, which is enriched in cortical granules. To evaluate the function of these proteins in CGE we set up a functional assay based on the quantification of cortical granules metaphase II oocytes activated parthenogenetically with strontium. Endogenous alpha-SNAP and NSF proteins were perturbed by microinjection of recombinant proteins or antibodies prior to CGE activation. The microinjection of wild type alpha-SNAP and the negative mutant of alpha-SNAP L294A in metaphase II oocytes inhibited CGE stimulated by strontium. NEM, an irreversibly inhibitor of NSF, and the microinjection of the negative mutant NSF D1EQ inhibited cortical reaction. The microinjection of anti-alpha-SNAP and anti-NSF antibodies was able to abolish CGE in activated metaphase II oocytes. The microinjection of anti-gamma SNAP antibody had no effect on CGE. Our findings indicate, for the first time in any oocyte model, that alpha-SNAP, gamma-SNAP, and NSF are expressed in mouse oocytes. We demonstrate that alpha-SNAP and NSF have an active role in CGE and pro