Angular dispersion of protons passing through thin metallic films Archubi, Claudio Darío; Denton, C.; Eckardt, J. C.; Lantschner, G. H.; Arista, N. R.; Valdés, J.; Ferrón, J. The angular distributions of protons after traversing thin polycrystalline Al targets (∼15 nm) with an incident energy of 10 keV have been measured and an analysis of the targets by means of transmission electron microscopy (TEM) techniques has been made. The separate influence of the different crystal characteristics and defects has been evaluated by numerical simulation considering the interaction of the ion with all the nearest neighboring atoms simultaneously. In the analysis we included the evaluation of the effects of lattice vibrations, oxide layers and foil roughness on the angular distributions. Previous experimental data in monocrystalline and polycrystalline Au targets has also been analyzed. For a consistency check a comparison with the results of the MARLOWE code for the simpler case of proton channeling in 〈1 0 0〉 Al has been performed. As in the case of Au, the present results indicate that the experiments can be explained in terms of a modified Moliere potential, and confirm the critical influence of crystal characteristics, in this case the amorphous oxide layer on the surface and the thermal vibration of the lattice atoms.

Galectin-1 sensitizes resting human T lymphocytes to Fas (CD95)-mediated cell death via mitochondrial hyperpolarization, budding, and fission. Matarrese, Paola; Tinari, Antonella; Mormone, Elisabetta; Bianco, German Ariel; Toscano, Marta Alicia; Ascione, Barbara; Rabinovich, Gabriel Adrián; Malorni, Walter Galectins have emerged as a novel family of immunoregulatory proteins implicated in T cell homeostasis. Recent studies showed that galectin-1 (Gal-1) plays a key role in tumor-immune escape by killing antitumor effector T cells. Here we found that Gal-1 sensitizes human resting T cells to Fas (CD95)/caspase-8-mediated cell death. Furthermore, this protein triggers an apoptotic program involving an increase of mitochondrial membrane potential and participation of the ceramide pathway. In addition, Gal-1 induces mitochondrial coalescence, budding, and fission accompanied by an increase and/or redistribution of fission-associated molecules h-Fis and DRP-1. Importantly, these changes are detected in both resting and activated human T cells, suggesting that Gal-1-induced cell death might become an excellent model to analyze the morphogenetic changes of mitochondria during the execution of cell death. This is the first association among Gal-1, Fas/Fas ligand-mediated cell death, and the mitochondrial pathway, providing a rational basis for the immunoregulatory properties of Gal-1 in experimental models of chronic inflammation and cancer.

El agua en la Produccion de cultivos extensivos: III. Impacto de las practicas de manejo sobre la eficiencia de uso del agua Micucci, Federico; Alvarez, Carina Rosa El agua es el factor más limitante en la producción de cultivos extensivos en secano en la región pampeana argentina y en muchas otras regiones del mundo. Por lo tanto, debemos saber producir haciendo un uso eficiente del recurso más escaso, el agua. El objetivo de este artículo es brindar algunos conceptos básicos relacionados con la eficiencia de uso del agua (EUA) y las prácticas de manejo que la mejoran. Para ello es necesario conocer cuales son los componentes de la EUA posibles de modificar y como las prácticas agronómicas pueden afectarla.

Sunflower chlorotic mottle virus in compatible interactions with sunflower: ROS generation and antioxidant response Arias, Maria Cecilia; Luna, Celina Mercedes; Rodríguez, Marianela; Lenardon, Sergio Luis; Taleisnik, Edith Sunflower chlorotic mottle virus (SuCMoV) is a recently described potyvirus that causes systemic infections in sunflower plants leading to chlorotic mottling and important growth reductions and yield losses. Oxidative damage is expressed after symptom development in this host-pathogen combination. The involvement of antioxidant enzyme activities in disease susceptibility was studied in two sunflower lines differing in the intensity and rate of development of SuCMoV infections: L2 is more susceptible than L33. A transient superoxide production peak was detected in leaves of both lines before symptom development. H2O2 accumulation increased before symptom expression in infected plants of L33 but in L2 such increase was registered only after symptoms became evident. In healthy plants of both lines, superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) showed similar activity levels. In inoculated plants of line L2, but not in L33, SOD and CAT activities increased significantly before the appearance of symptoms, and APX increases were detected later. A 1 mM SA treatment effectively decreased SuCMoV accumulation in plants of L2 but it did not affect it in L33. This treatment increased H2O2 accumulation and prevented the increase in antioxidant enzyme activities in infected plants of L2. It is suggested that increases in antioxidant enzyme activities interrupted the signals generated by the increase in ROS, which may have otherwise triggered defence reactions in the host and thus, resulted in a compatible interaction.

Scanning electron microscopy of Chordodes moutoni Camerano, 1895 (Gordiida, Nematomorpha) Zanca, Fernanda Mariel; De Villalobos, Cristina Taxonomic characters of both male and female horse-hair worms Chordodes moutoni Camerano, 1895 (Nematomorpha) are re-described using scanning electron microscopy. The features are compared with the original description. C. moutoni cuticle has five different areolar types in male while female have six types of areoles. The crowned areoles, characteristic of Chordodes, are surrounded by other areoles forming pairs or clusters. Sexual dimorphism was found in the cuticular pattern, the female showing two different types of crowned areoles with distinct distribution pattern while the male has only one type of crowned areoles. These data are compared to other Chordodes species that have been studied.

Neuronal differentiation in the adult hippocampus recapitulates embryonic development Esposito, Maria Soledad; Piatti, Veronica del Carmen; Laplagne, Diego Andres; Morgenstern, Nicolás Andrés; Ferrari, Carina Cintia; Pitossi, Fernando Juan; Schinder, Alejandro Fabián In the adult hippocampus and olfactory bulb, neural progenitor cells generate neurons that functionally integrate into the existing circuits. To understand how neuronal differentiation occurs in the adult hippocampus, we labeled dividing progenitor cells with a retrovirus expressing green fluorescent protein and studied the morphological and functional properties of their neuronal progeny over the following weeks. During the first week neurons had an irregular shape and immature spikes and were synaptically silent. Slow GABAergic synaptic inputs first appeared during the second week, when neurons exhibited spineless dendrites and migrated into the granule cell layer. In contrast, glutamatergic afferents were detected by the fourth week in neurons displaying mature excitability and morphology. Interestingly, fast GABAergic responses were the latest to appear. It is striking that neuronal maturation in the adult hippocampus follows a precise sequence of connectivity (silent → slow GABA → glutamate → fast GABA) that resembles hippocampal development. We conclude that, unlike what is observed in the olfactory bulb, the hippocampus maintains the same developmental rules for neuronal integration through adulthood.

Fetal but not adult Leydig cells are susceptible to adenoma formation in response to persistently high hCG level; a study on hCG overexpressing transgenic mice Ahtianen, Petteri; Rulli, Susana Beatriz; Shariatmadari, Ramin; Pelliniemi, Lauri J.; Toppari, Jorma; Poutanen, Matti; Huhtaniemi, Ilpo T. We have previously demonstrated that male transgenic (TG) mice overexpressing human chorionic gonadotropin (hCG+) develop reproductive organ defects, but no tumors, in adult age. In this study, the effects of persistently elevated hCG were followed in TG males between day 5 postpartum and adulthood. Leydig cell (LC) adenomas were found in prepubertal mice, most prominently at the age of 10 days, but not in adult age. Serum testosterone concentrations were significantly increased in TG males at all ages studied. The phenotype of the prepubertal hCG+ males resembled that found in boys upon expression of constitutively activating luteinizing hormone (LH) receptor mutations. The temporal expression patterns of the fetal LC marker gene, thrombospondin 2, and those of adult LCs, hydroxysteroid dehydrogenase-6, delta5-3-beta and prostaglandin D synthase, were similar in wild-type and hCG+ males. Hence, the postnatal adenomas resemble functionally fetal LCs, and only these cells are susceptible to hCG-induced tumorigenesis. Our findings demonstrate a novel intriguing difference between the fetal and adult LC populations and provide further insight into the potential tumorigenic effects of gonadotropins.

Diversity of rhizobia isolated from an agricultural soil in Argentina based on carbon utilization and effects of herbicides on growth Zabaloy, Maria Celina; Gomez, Marisa Anahi Seventy-six rhizobial isolates belonging to four different genera were obtained from root nodules of several legumes (Vicia sativa, Vicia faba, Medicago sativa, Melilotus sp., Glycine max and Lotus corniculatus). The action of five commonly used herbicides (2,4-dichlorophenoxyacetic acid [2,4-D], glyphosate [GF], dicamba, atrazine and metsulfuron-methyl), on the growth of rhizobial strains was assessed. Subsequently, GF and 2,4-D were tested in a minimum broth as C and energy sources for twenty tolerant strains. The ability of these strains to metabolize different carbon sources was studied in order to detect further differences among them. Tolerance of the bacteria to agrochemicals varied; 2,4­-D and GF in solid medium inhibited and diminished growth, respectively, in slow-growing rhizobial strains. Among slow-growing strains we detected Bradyrhizobium sp. SJ140 that grew well in broth+GF as the sole C and energy source. No strain was found which could use 2,4-D as sole C source. The twenty strains studied exhibited different patterns of C sources utilization. Cluster analysis revealed three groups, corresponding to four genera of rhizobia: Rhizobium (group I), Sinorhizobium (group II) and Mesorhizobium-Bradyrhizobium (group III). On the basis of the results obtained on responses to herbicides and C sources utilization by the isolates investigated, it was possible to differentiate them at the level of strains. These results evidenced a considerable diversity in rhizobial populations that has not been previously described for Argentinean soils, and suggested a physiological potential to use natural and xenobiotic C sources.

Analysis of the use of voltammetric results as a steady state approximation to evaluate kinetic parameters of the hydrogen evolution reaction Marozzi, Carlos Alberto; Canto, Mario Ruben; Costanza, Vicente; Chialvo, Abel Cesar The use of the voltammetric response jvol(η) of a potentiodynamic sweep at a slow scan rate vs in place of a steady state polarization curve jss(η) for the determination of the kinetic parameters of the hydrogen evolution reaction is analyzed. It is proposed to consider jvol(η, vs) ∼= jss(η) when the condition 0.99 ≤ jvol(η, vs)/jss(η) ≤ 1.01 is verified in the overpotentials range η≤−0.05V. It has been also established a simple relationship between the maximum admissible scan rate vmax s and the equilibrium polarization resistance Rp. Finally, the application of this criterion on different electrodes is described and discussed.

Effects of formulation concentration on intravenous pharmacokinetics, chirality and in vitro solubility of oxfendazole and its metabolites in sheep Sanchez Bruni, Sergio Fabian; Jones, Douglas G.; Small, John; McKellar, Quintin A. This study compared pharmacokinetic (PK) profiles in sheep dosed intravenously with three different concentrations of oxfendazole (OFZ).  An in vitro plasma OFZ dissolution study provided additional information on plasma saturation.  For the PK study, 18 adult, parasite-free, female Suffolk cross sheep, allocated into three groups (n=6), were treated intravenously, at a dose rate of 5mg/kg bodyweight, with aqueous solutions containing at 4, 8 or 16% OFZ.  Plasma drug concentrations were measured, for up to 72 hours post-treatment, by a validated high performance liquid chromatography (HPLC) method with UV detection.  OFZ and fenbendazole sulphone (FBZSO2) were the main metabolites detected in all three experimental groups. In animals given the 4% solution, OFZ depleted according to a biexponential concentration vs. time curve.  In contrast, those given 8 or 16% preparations produced atypical curves fitted by monoexponential equations. No statistically significant differences in area under concentration-time curves (AUC) were observed, but concentration-dependent differences in distribution and mean residence time (MRT) were evident.  Compared with 4% OFZ, animals treated with 8 and 16% formulations had slower half-lives of metabolite formation,and lower AUC’s, suggesting that OFZ sulphonation may have been modified.  In vitro there was evidence of plasma saturation and precipitation associated with 8 and 16% OFZ preparations.  It is concluded that differences in PK profiles, in vivo, may have been related to inadequate dissolution and/or tissue drug precipitation.

Impact of the Placental Cytokine-Chemokine Balance on Regulation of Cell-Cell Contact-Induced Human Immunodeficiency Virus Type 1 Translocation across a Trophoblastic Barrier In Vitro Derrien, Muriel; Faye, Albert; Dolcini, Guillermina Laura; Chaouat, Gérard; Barré Sinoussi, Françoise; Menu, Elisabeth Cells constituting the placental barrier secrete soluble factors that may participate in controlling human immunodeficiency virus type 1 (HIV-1) transmission from the mother to the fetus. In this study, we asked whether placental soluble factors (PSF) could limit cell-cell contact inducing HIV-1 production that occurs after inoculation of HIV-1-infected peripheral blood mononuclear cells (HIV-1+ PBMCs) onto trophoblast-derived BeWo cells grown as tight and polarized barriers in a two-chamber system. The activity of recombinant chemokines and cytokines expressed by placental tissue and of factors secreted by either early or term placentae of HIV-1-negative women, was analyzed. We identified chemokines (RANTES and MIP-1beta) and cytokines (tumor necrosis factor alpha and interleukin-8) that decreased and increased, respectively, viral production in trophoblast barrier cells inoculated with HIV-1+ PBMCs. Unexpectedly, factors secreted by either early or term placentae of HIV-1-negative women enhanced viral production. Nevertheless, the same PSF did not favor infection of trophoblastic barriers with cell-free HIV-1 and strongly reduced viral production in PBMCs infected with cell-free HIV-1. Moreover, PSF contained chemokines (RANTES and MIP-1beta) and a cytokine, leukemia inhibitory factor, exhibiting a strong anti-HIV-1 activity in our model of cell-to-cell infection. Together these data suggested that at the maternal interface the global activity of PSF is related to the synergistic action of several soluble factors with a balance in favor of an enhancing activity on the passage of viruses across the trophoblast barrier. This could explain the presence of viral sequences in trophoblasts in all placentae of HIV-1-infected women.

The effect of different slurry compositions and solvents upon the properties of ZSM5-washcoated cordierite honeycombs for the SCR of NO x with methane Zamaro, Juan Manuel; Ulla, Maria Alicia del H.; Miro, Eduardo Ernesto ZSM5-washcoated monoliths were prepared using different slurry compositions and the following solvents: water, methyl alcohol, ethyl alcohol, isopropyl alcohol, butyl alcohol, ethyl acetate, and acetone. The effect of the different solvents on the coating characteristics was studied and two of their properties, viscosity and volatility, were used to analyze the results obtained. The solvents giving rise to high-viscosity slurries - butyl alcohol, ethyl acetate, and acetone - were not effective for the washcoating process. In the case of the other solvents, when viscosity and vapor pressure increased the load obtained was higher, probably due to a combined effect of viscosity and partial evaporation during the blowing step. Water yielded zeolite coatings with the best mechanical stability, measured by ultrasonic test. When water was used as solvent, the zeolite load increased linearly with the square root of viscosity. Finally, an In/HZSM5-coated honeycomb was tested for NOx reduction with methane under excess oxygen. It showed a behavior very similar to that of the powder catalyst, which is one of the main objectives pursued when coating monoliths.

Time’s arrow and irreversibility in time-asymmetric quantum mechanics Castagnino, Mario Alberto G. J.; Gadella, Manuel; Lombardi, Olimpia Iris The aim of this paper is to analyze time‐asymmetric quantum mechanics with respect to the problems of irreversibility and of time’s arrow. We begin with arguing that both problems are conceptually different. Then, we show that, contrary to a common opinion, the theory’s ability to describe irreversible quantum processes is not a consequence of the semigroup evolution laws expressing the non‐time‐reversal invariance of the theory. Finally, we argue that time‐asymmetric quantum mechanics, either in Prigogine’s version or in Bohm’s version, does not solve the problem of the arrow of time because it does not supply a substantial and theoretically founded criterion for distinguishing between the two directions of time.

Las aporías de la democracia recobrada: la construcción del ciudadano en Argentina Cernadas, Mabel Nelida El proceso de democratización en la Argentina de las últimas décadas se produjo en medio de los cambios del contexto internacional y de una crisis intensa y sostenida que han condicionado su consolidación. Conspiran contra el mismo entre otras cuestiones, la erosión del orden estatal, los desajustes económicos, el endeudamiento externo, la desintegración y exclusión social así como también las marcadas tendencias de fragmentación cultural. A todo esto se suma la profunda crisis de legitimidad y representación política. El presente artículo realiza una breve reflexión respecto a los profundos cambios que se advierten en la sociedad argentina en las últimas décadas y la manera que ellos han transformado los ejes en torno a los cuales se articulan la participación y el ejercicio de la ciudadanía, entendidas ambas como prácticas culturales que varían de acuerdo a los contextos en que se insertan. Se repasa la historia de la democracia argentina desde el período de la ilusión democrática, inaugurado en 1983, hasta la crisis que sacudió las instituciones y la vida política del país, prestando especial atención a la participación de los nuevos movimientos sociales.

Sol-gel coatings on carbon steel: Electrochemical evaluation Pepe, Andrés; Galliano, Pablo German; Aparicio, Mario; Duran, Hebe Alicia; Ceré, Silvia Degradation of carbon steel has always been a concern. The use of coatings is especially recommended in aggressive atmospheres at moderate temperatures. Ceramic films can be used to improve the resistance against high temperature oxidation and corrosion of metals. Amid the different options, a sol-gel process provides a low cost, simple and non-hazardous method for processing ceramic coating with controllable composition and microstructure. This work evaluates the electrochemical behaviour of carbon steel coated by sol-gel method. Hybrid organic-inorganic silica sol-gel coatings were obtained by dip coating of planar samples in an organically modified silica sol made from hydrolysis and polycondensation of tetra-orthosilicate (TEOS) and methyltriethoxisilane (MTES) by acidic catalysis. Coatings free of defects were obtained at a sintering temperature of 400 °C. The coated samples were inspected by optical and electron microscopy and coating thickness was measured by using a Talystep surface roughness tester. Electrochemical evaluation was made by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curves. A comparison of the corrosion resistance of the coated metal with the uncoated one is presented. The measurements show the improvement of the corrosion resistance of the coated carbon steel.

The influence of dehydroepiandrosterone on early pregnancy in mice Sander, Valeria Analía; Solano, Maria Emilia; Elia, Evelin Mariel; Luchetti, Carolina Griselda; Di Girolamo, Guillermo; Gonzalez, Claudio; Motta, Alicia Beatriz The aim of the present report was to study the role of high levels of dehydroepiandrosterone (DHEA) on the ovarian function and embryonic resorption during early pregnancy in BALB/c mice. Pregnant animals were injected with DHEA following both the post-implantatory (DHEA-2) and peri-implantatory (DHEA-6) models. Morphological studies of implantation sites showed 40% of embryonic resorption in the DHEA-2 group while 100% of resorption was observed in the DHEA-6 group. Serum samples of both DHEA-2 and DHEA-6 groups showed higher estradiol levels and a lower progesterone concentration than those of control groups. Ovarian prostaglandin E levels after both DHEA-2 and DHEA-6 treatments increased when compared to control groups. The antioxidant metabolite glutathione diminished during both DHEA treatments. In summary, the data presented here suggest that DHEA treatment during early pregnancy modulates the ovarian function and is responsible for embryonic resorption with different degrees depending on when it is administered.

Galaxy groups in the third data release of the sloan digital sky survey Merchan, Manuel Enrique; Zandivarez, Arnaldo Ariel We present a new sample of galaxy groups identified in the Sloan Digital Sky Survey Data Release 3. Following previous works, we use the well-tested friends-of-friends algorithm developed by Huchra and Geller, which takes into account the number density variation due to the apparent magnitude limit of the galaxy catalog. To improve the identification, we implement a procedure to avoid the artificial merging of small systems in high-density regions and then apply an iterative method to recompute the group centers position. As a result, we obtain a new catalog with 10,864 galaxy groups with at least four members. The final group sample has a mean redshift of 0.1 and a median velocity dispersion of 230 km s-1.

Development of an electroanalytical method for the quantification of zearalenone (ZEA) in maize samples Ramírez, Eduardo Alejandro; Molina, Patricia Gabriela; Zón, María Alicia; Fernández, Héctor The application of electroanalytical techniques to detect and quantify zearalenone (ZEA) mycotoxin that frequently contaminates maize and foodstuff is studied in this work. Rice and maize grains were inoculated with Fusarium fungus to obtain ZEA in artificially infected samples. The electro-oxidation of ZEA adsorbed on the surface of glassy carbon (GC) electrodes in 20% acetonitrile (ACN) + 80% 1 M HClO4 (aqueous solution) reaction medium was studied by using square-wave voltammetry (SWV). Studies were conducted to find the most favorable accumulation potential (Eacc) and accumulation time (t acc) to perform the ZEA preconcentration on the electrode surface. It was found that Eacc was any value in the range from 0.00-0.90 V and the best tacc was 120 s, respectively, for ZEA separated from extracting solution by TLC (ZEATLC) while Eacc = 0.90 V corresponded to ZEA in non separated matrix solution (ZEAmatrix). The ZEA quantitative determination was performed by SWV combined with the standard addition method. Linear plots were obtained from the net peak current (I p, n) vs c*ZEA in the concentration range from 20 to 3184 ppb. Detection limit of 30 ppb at a signal to noise ratio of 3:1 was obtained. On the other hand, recovery experiments were performed on uncontaminated maize samples spiked with ZEA.

Cloud point preconcentration prior to capillary zone electrophoresis: Simultaneous determination of platinum and palladium at trace levels Cerutti, Estela Soledad; Silva, María Fernanda; Gasquez, José Antonio; Olsina, Roberto Antonio; Martinez, Luis Dante The incorporation of a cloud point extraction (CPE) step prior to capillary electrophoresis (CE) for simultaneously determining platinum and palladium at sub-μg/L levels is presented and evaluated. The analytes were extracted as 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol complexes, at pH 2.0, mediated by micelles of the nonionic surfactant polyethyleneglycolmono-p-nonylphenyl ether (PONPE 7.5). The separation-determination step was developed from 150 μL of the extracted surfactant-rich phase diluted with 50 μL of acetonitrile (ACN). An exhaustive study of the variables affecting the cloud point extraction with PONPE 7.5 and the CZE step was done. The type and composition of the background electrolytes (BGEs) were investigated with respect to separation selectivity, reproducibility, and stability. A BGE of 50 mM monobasic sodium phosphate containing 30% ACN, pH 4.53 was found to be optimal for the separation of metal chelates. Detection was performed at 576 nm. An enrichment factor of 250 was obtained for the preconcentration of 50 mL of sample solution. The detection limits for the preconcentration of 50 mL of sample were 0.04 μg/L for Pt and 0.08 μg/L for Pd. As an analytical demonstration, ultratrace concentrations of platinum and palladium were conveniently quantitated in spiked water and urine samples. © 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Multichannel radiometer calibration: A new approach Diaz, Susana Beatriz; Booth, Charles R.; Armstrong, Roy; Brunat, Claudio; Cabrera, Sergio; Camilion, Carolina; Casiccia, Claudio; Deferrari, Guillermo Alejandro; Fuenzalida, Humberto; Lovengreen, Charlotte; Paladini, Alejandro Alberto; Pedroni, Jorge; Rosales, Alejandro; Zagarese, Horacio Ernesto; Vernet, Maria The error in irradiance measured with Sun-calibrated multichannel radiometers may be large when the solar zenith angle (SZA) increases. This could be particularly detrimental in radiometers installed at mid and high latitudes, where SZAs at noon are larger than 50° during part of the year. When a multi-regressive methodology, including the total ozone column and SZA, was applied in the calculation of the calibration constant, an important improvement was observed. By combining two different equations, an improvement was obtained at almost all the SZAs in the calibration. An independent test that compared the irradiance of a multichannel instrument and a spectroradiometer installed in Ushuaia, Argentina, was used to confirm the results.