1940, un año en revisión. La Argentina y la repercusión regional de la Segunda Guerra Mundial Figallo, Beatriz Josefina Este trabajo pretende abordar la confluencia entre repercusiones producidas por la guerra en el cono sur, la neutralidad de la Argentina -postura que entonces compartió activamente con el resto de América- y los problemas que se suscitaron en el plano de la defensa hemisférica y de las vinculaciones con los países lindantes, entendiendo que son conocidos los aportes clásicos que han tratado aquellos días. Nuestra mirada revisa un año en particular, el de 1940, crucial como todos los de la guerra, aunque decisivo para la Argentina cuando crisis internacional, regional e institucional convergieron, con actitudes y decisiones que se explican mutuamente y se comprenden más, en la comparación.

Effect of the nature of the starting material on the formation of Mg2FeH6 Castro, F. J.; Gennari, Fabiana Cristina The compound Mg2FeH6 was synthesized in a single process by reactive mechanical alloying (RMA) a 2MgH2+Fe mixture under hydrogen atmosphere at room temperature. The process yield is 15.6 wt.% of Mg2FeH6, after 100 h of milling. The synthesis of Mg2FeH6 takes almost twice the time and gives nearly half the yield obtained when milling a 2Mg+Fe mixture under similar conditions. The differences observed are explained in terms of the contrast between the mechanical properties and the microstructures of the starting mixtures.

Isobornyl Methacrylate as a Reactive Solvent of Polyethylene Schnell, Matthias; Borrajo Fernandez, Julio; Williams, Roberto Juan Jose; Wolf, Bernhard A. Solutions containing 15 wt % of a low-molar-mass polyethylene (PE) in isobornyl methacrylate (IBoMA), containing 0, 5 or 10 wt % of 1,4 butanediol dimethacrylate (BDDMA) as crosslinker, were polymerized using either benzoyl peroxide (BPO), at 80 ºC, or dicumyl peroxide (DCPO), with a thermal cycle attaining 150 ºC, as initiators. Phase separation of an amorphous PE-rich phase took place when carrying out the reaction at temperatures higher than the PE melting temperature. Partial crystallization of PE was observed when cooling to room temperature. Depending on the initial amount of BDDMA, the fraction of PE that was phase separated varied between 57 % and 66 % of the initial amount, with crystalline fractions in the range of 15 % to 42 %. The use of IBoMA as a reactive solvent of PE has two main advantages over other reactive solvents reported in the literature: a) it has a very low vapor pressure, and b) its free-radical polymerization gives a polymer with a relatively high glass transition temperature.

DAWN en América Latina y el Caribe Gagliardino, Juan Jose Relativamente pocos estudios han examinado el impacto psicosocial de la diabetes. El programa DAWN (Diabetes, Attitudes, Wishes and Needs) trató este problema en un estudio en el que participaron personas con diabetes de 13 países. La conclusión fue que la depresión era mucho más común entre las personas con diabetes que entre quienes no tienen la afección, y se asoció a alteraciones del autocontrol y de la calidad de vida. Aunque los países de América Latina y el Caribe no participaron del estudio DAWN, sus concluisiones aplican a la atención de la diabetes de la región. En este artículo, Juan José Gagliardino nos habla de la aplicación de las conclusiones del programa DAWN dentro de un contexto latinoamericano y caribeño.

Metodología para evaluar riesgo de erosión hídrica en el suroeste de la provincia de Córdoba, Argentina; A methodology to evaluate water erosion risk in the southwest of Cordoba province, Argentina Cantu, Mario Pablo; Becker, Analia Rosa; Musso, Telma Belén The aim of this work was to prove a methodology to evaluate water erosion risk in La Colacha basin in the Southwest of Cordoba Province, Argentina. The susceptibility to soil erosion was established through the evaluation of parameters which are involved in water erosion such as geomorphologic, lithologic, previous erosion and soil parameters. In this area, changes in land use have produced an increment in water erosion processes due to the alteration of physical, chemical and biochemical soil conditions. This led us to consider these changes as the hazard. Erosion risk was considered as the product between susceptibility and hazard. Susceptibility, hazard and risk maps were obtained through a GIS. The results showed that La Colacha basin presented low water erosion risk in most of its area. Units with slopes lower than 1% under a beef cattle production system did not present water erosion risk. Areas with slopes higher than 3% under a conventional tillage crop production system showed a moderately water erosion risk. Low water erosion risk classes corresponded to sites with intermediate slopes. This methodology permits to obtain a rapid assessment of water erosion risk and can be used in a medium scale territorial and environmental planification. The method can be applied in other environments through assigning indexes according with the characteristics of the site and with a right evaluation of land use pressure. The advantage of this methodology is that it may be easily applied using only a soil map.

Lipase-catalysed deacetylation of androstane and pregnane derivatives: Influence of ring D substitution Bruttomesso, Andrea; Baldessari, Alicia A series of acetoxy derivatives of androstane and pregnane was deacetylated in organic solvents by microbial lipases. The best results were obtained with lipase from Candida antarctica (CAL B), Candida rugosa (CRL) and Pseudomonas sp. (PSL). In some derivatives, CAL B and CRL showed a regioselective behaviour towards the removal of the 3β- or 16α/16β-acetyl group. The results of the enzymatic deacetylation of pregnanes and androstanes substituted by various groups containing an sp2-hybridised C-atom in ring D could suggest that CAL B activity seems to be conditioned by the occurrence of a polar carbon double bond in this part of the steroid skeleton. Ten new steroid derivatives were obtained through this approach.

Adrenal gland involvement in the regulation of renal 11beta-hydroxysteroid dehydrogenase 2 Zallocchi, Marisa Laura; Matkovic, Laura Beatriz; Calvo, Juan Carlos; Damasco, Maria Cristina Renal 11beta-hydroxysteroid dehydrogenase 2 (HSD2) catalyzes the conversion of active glucocorticoids to inert 11beta-keto compounds, thereby preventing the illicit binding of these hormones to mineralocorticoid receptors (MRs) and, thus, conferring aldosterone specificity. Absence or inhibition of HSD2 activity, originates a hypertensive syndrome with sodium retention and increased potassium elimination. Recent studies from our laboratory reported an increment of HSD2 activity in intact-stressed rats. To evaluate the adrenal involvement in this increase, we analyzed HSD2 activity and protein abundance in Intact, Sham-operated, and adrenalectomized rats under stress situations (gavage with an overload of 200 mM HCl (10 ml) and simulated gavage) or with corticosterone replacement. HSD2 activity was assessed in renal microsomal preparations obtained from different groups of animals. HSD2 protein abundance was measured by Western-blot. Circulating corticosterone was determined by radioimmunoassay. Sham-operated animals showed an increase in HSD2 activity and abundance compared to Intact and adrenalectomized rats suggesting the involvement of stress-related adrenal factors in HSD2 regulation. In the case of acidotic adrenalectomized animals, there was an increase in renal HSD2 activity when, along with the HCl overload, the rats were injected with corticosterone. This increment occurred without an increase in enzyme abundance. These results suggest the importance of circulating levels of glucocorticoids to respond to a metabolic acidosis, through regulation of HSD2 stimulation. The group subjected to a simulated gavage showed an increase in enzyme activity and protein abundance, thus demonstrating the need for both adrenal and extra-factors in the modulation of renal HSD2. The adrenalectomized animals injected with different doses of corticosterone, produced a progressive increase in enzyme activity and abundance, being significant for the dose of 68 microg corticosterone/100 g body weight. The highest dose (308 microg/100 g body weight) did not show any variation in activity and abundance compared to the control group. This biphasic effect of glucocorticoids could be explained taking into account their permissive and suppressive actions, depending on their blood levels. Knowing that stress induces multifactorial responses, it should not be surprising to observe a differential regulation in renal HSD2, confirming that different stressors act through different factors of both, adrenal and extra-adrenal origin.

Continuum approach to the numerical simulation of material failure in concrete Oliver, J.; Huespe, Alfredo Edmundo; Samaniego, E.; Chaves, E. W. V. Some new aspects of the continuum strong discontinuity approach (CSDA) to model material failure in geomaterials are addressed. A new global algorithm, for tracking multiple crack lines/surfaces in 2D/3D cases is proposed. It is based on solving a simple heat conduction-like problem accompanying the standard mechanical algorithm. A viscous perturbation method on the crack surface is also proposed to remedy the instabilities caused by mutual interactions of multiple developing cracks. A simple procedure to compute the critical time step that ensures algorithmic uniqueness is then provided. Numerical simulations of two and three-dimensional problems displaying a multi-crack pattern are finally presented

ALE method for solidification modelling Bellet, Michel; Fachinotti, Victor Daniel In this paper an arbitrary Lagrangian-Eulerian (ALE) formulation has been developed for the simulation of casting processes. The method is applied both to mould filling simulation, where it can provide accurate free surface description, and to the study of thermo-mechanical phenomena occurring in the subsequent cooling down of cast parts: prediction of solute transport and of distortions and stresses. In the first three sections, all governing equations
(constitutive equations, momentum, energy, solute transport) are given. Then the ALE formulation is presented: mesh updating with evolving free surfaces, using "conservative" normal vectors to enforce mass conservation; treatment of advection terms, using an original nodal upwind method; definition of Lagrangian and Eulerian-Lagrangian regions. Finally, examples of applications are given.

Surface Reconstruction and Decahedral Structure of Bimetallic Nanoparticles Rodríguez-López J. L.; Montejano-Carrizales, J. M.; Pal, U.; Sánchez-Ramírez, J. F.; Troiani, Horacio Esteban; García, D.; Miki-Yoshida, M.; José-Yacamán, M. We report on energetic surface reconstruction phenomena observed on bimetallic nanoparticle systems of AuPd and AuCu, similar to a resolidification effect observed during the cooling process in lead clusters. These binary alloy nanoparticles show the fivefold edges truncated, resulting in { 100 } facets on decahedral structures, an effect largely envisioned and reported theoretically, with no experimental evidence so far. We demonstrate experimentally as well as by computational simulations that this new eutectic structure is favored in such nanoalloy systems.

Effect of chlorine on filamentous microorganisms present in activated sludge as evaluated by respirometry and INT-dehydrogenase activity Caravelli, Alejandro Horacio; Giannuzzi, Leda; Zaritzky, Noemi Elisabet Activated sludge technology is more used than any other for biological treatment of wastewater. However, filamentous bulking is a very common problem in activated sludge plants, chlorine being the chemical agent normally used to control it. In this work the effect of chlorine on micro-organisms present in activated sludge flocs was assessed by a respirometric technique (oxygen uptake rate, OUR) and by the INT-dehydrogenase activity test (DHA) measured by two techniques: spectrophotometry (DHA a) and image analysis (DHA i). Both DHA tests were optimized and correlated with the respirometric technique (OUR) using pure cultures of a filamentous micro-organism (Sphaerotilus natans) under chlorine inhibition. Using these correlations the tested methods were applied to determine the action of chlorine on respiratory activity in activated sludge. The OUR and the DHA a quantifies the action of chlorine on the total respiratory activity (RA) of flocs (filamentous and floc-forming bacteria); in contrast, the DHA i test evaluates specific action of chlorine on the RA of filamentous micro-organisms. In activated sludge flocs containing filamentous microorganisms, a chlorine dose of 4.75 mgCl2 (gVSS)-1 with a contact time of 20 minutes reduced about 80% of the RA of filamentous bacteria while affecting only 50-60% of the total RA of flocs. Besides, a chlorine dose of 7.9 mgCl2 (gVSS)-1 produced the total respiratory inactivation of filamentous micro-organisms after 10 min contact, however, with this dose the total RA of activated sludge flocs was reduced only about 45-65%; controlling filamentous bulking without affecting too much floc-forming bacteria. At the tested chlorine concentrations the inhibition of filamentous micro-organisms was higher than in the whole activated sludge. Although floc-forming micro-organisms were demonstrated to be more susceptible to chlorine than filamentous in pure cultures, results obtained in the present work confirmed that it is the location of the filamentous micro-organisms in the flocs and the presence of extracellular polymers substances which largely determines their higher susceptibility to chlorine; consequently this feature plays a critical role in bulking control. Although floc-forming micro-organisms were demonstrated to be more susceptible to chlorine than filamentous in pure cultures, results obtained in the present work confirmed that it is the location of the filamentous micro-organisms in the flocs and the presence of extracellular polymers substances which largely determines their higher susceptibility to chlorine; consequently this feature plays a critical role in bulking control.

Herpes simplex virus thymidine kinase/ganciclovir system in multicellular tumor spheroids Finocchiaro, Liliana Maria Elena; Bumaschny, Viviana Florencia; Karara, Armando Luis; Fiszman, Gabriel Leon; Casais, Cecilia C.; Glikin, Gerardo Claudio We have developed multicellular spheroids (MCS) established from LM05e and LM3 spontaneous Balb/c-murine mammary adenocarcinoma and B16 C57-murine melanoma derived cell lines as an in vitro model to study the efficacy of the herpes simplex virus thymidine kinase/ganciclovir (HSVtk/GCV) suicide system. We demonstrated for the first time that HSVtk-expressing cells assembled as MCS manifested a GCV resistance phenotype compared to the same cells grown as sparse monolayers. HSVtk-expressing LM05e, LM3 and B16 spheroids were 16-, three- and nine-fold less sensitive to GCV than their respective monolayers, even though they could express transgenes 10-, eight- and five-fold more efficiently. Mixed populations of HSVtk- and their respective βgal-expressing cells displayed a cell-type specific bystander effect that was higher in monolayers than in MCS. However, HSVtk-expressing cells in two- or three-dimensional cultures were always significantly more sensitive to GCV than the βgal-expressing counterparts, supporting the feasibility of this suicide approach in vivo. We present evidence showing that HSVtk-expressing tumor cells, when transferred from monolayers to MCS, displayed: (i) lower GCV cytotoxic activity and bystander effect; (ii) higher and efficient expression of genes transferred as lipoplexes; (iii) lower cell proliferation rates; and (iv) changes in intracellular Bax/Bcl-xL rheostat of mitochondria-mediated apoptosis.

A 2-D model of Rayleigh instability in capillary tubes–surfactant effects Campana, Diego Martin; Di Paolo, José; Saita, Fernando Adolfo The Rayleigh instability of stagnant liquid films lining the interior of capillary tubes is analyzed with the aid of a 2-D free surface flow model; this axisymmetric model is previously validated using already published theoretical and experimental results. The Galerkin-finite element method is used to transform the complete set of governing equations and boundary conditions into a discrete set, which is then simultaneously solved at each time step by Newton’s method. Predictions of well known simplified models represented by nonlinear evolution equations derived on the one-dimensional flow assumption are compared with those obtained from the present one. The comparisons are made for pure liquids and also for liquids contaminated with insoluble surfactants; they show that the simpler models represent the free surface evolution reasonable well. However, the 1-D models generally underestimate the time needed to complete the unstable process that ends––if the film is thick enough––when the inner gas phase becomes disconnected due to the formation of liquid lenses regularly spaced; these discrepancies become larger when surface active agents are present. Surfactant effects and the wealth of information produced by the 2-D model are both evidenced through sample results presented at the end of the paper.

Large long-range F-F indirect spin-spin coupling constants. Prediction of measurable F-F couplings over a few nanometers Provasi, Patricio Federico; Aucar, Gustavo Adolfo; Sauer, Stephan P. A. Large long-range indirect nuclear spin coupling constants are of great interest for quantum computers. But they are rarely observed and are usually considered very small, unless the coupled nuclear spins are proximate in space. Looking for counterexamples, we have calculated F−F couplings in four different series of acyclic hydrocarbons (alkanes, conjugated polyenes, conjugated polyynes, and cumulenes) where the coupled fluorine nuclei are separated by up to 11 bonds or 1.4 nm. The calculations were carried out at the level of the second-order polarization propagator approximation using locally dense basis sets. This approach has, in recent years, been shown to be particularly successful in reproducing indirect nuclear spin−spin couplings in organic molecules. We find that the F−F couplings in saturated alkanes diminish very quickly with the number of bonds between the coupled fluorine atoms, whereas in the conjugated polyenes and in particular polyynes the F−F couplings can be transmitted over much longer distances. We predict that the F−F coupling over 9 bonds or 1.1 nm is 12 Hz in (1E,3E,5E,7E)-1,8-difluoroocta-1,3,5,7-tetraene and the coupling over 11 bonds or 1.4 nm is 7 Hz in difluorodecapentayne. Analyzing the four Ramsey contributions, we find that the F−F couplings in the polyenes are dominated by the spin−dipolar term, which is known to be favored by π-electronic systems, whereas in the case of the polyynes the orbital paramagnetic terms make the largest contributions, although the spin−dipolar and the Fermi contact contributions are also significant.

Beak deformation in an Antarctic Cormorant Phalacrocorax [atriceps] bransfieldensis chick Casaux, Ricardo Jorge

Dispersed phase morphology of impact PP copolymers. Effects of blend composition as determined by TREF Zacur Martinez, Ruth Maria; Goizueta, Graciela Susana; Capiati, Numa Jose Polypropylene (PP) blends, commercially known as 'impact polypropylene copolymers' (IPC), are produced by a sequential gas phase polymerization process. The final product is a complex mixture of polypropylene (PP) and a range of ethylene-propylene copolymers (EPC) with different ethylene contents. In the present work, the composition of three different IPC was estimated by performing a step elution mode Analytical Temperature Rising Elution Fractionation (TREF) separation. The recovered fractions were analyzed by Differential Scanning Calorimetry (DSC), Size Exclusion Chromatography (SEC) and Fourier Transform Infrared Spectroscopy (FTIR). The morphology was examined by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). Amorphous EPC were isolated in an independent way in order to perform a more careful characterization. The distinct particle size and shape of the dispersed phase for different IPC was interpreted in terms of the molecular characteristics of the blend components and their compositions.

Antioxidant Activity in Hepatopancreas of the Shrimp (Pleoticus muelleri ) by Electron Paramagnetic Spin Resonance Spectrometry Díaz, Ana Cristina; Fernandez Gimenez, Analia Veronica; Mendiara, Sara Noemí; Fenucci, Jorge Lino Free radical scavenging properties of hepatopancreas extracts of Pleoticus muelleri were evaluated by electron paramagnetic spin resonance spectrometry methods (EPR) against the stable 1,1-diphenyl2-picrylhydrazyl (DPPH) radical. The present study was carried out to characterize different physiological stages of the shrimp under environmental and nutritional stress, evaluating the effect on growth, survival, and functional morphology of the hepatopancreas. Feeding trials were carried out on juveniles (1 g initial weight) held in aquaria. Each diet, with different concentrations of vitamins A and E, was tested in triplicate groups during 25 days. The control groups were fed with fresh squid mantle and with a vitamin-free diet. For all of the diets, the extracts exhibited strong DPPH radical scavenging activity, suggesting that the tissue is a powerful natural antioxidant. Individuals fed with different concentrations of vitamin E showed the strongest effect on the DPPH radicals, reducing the DPPH radicals to 50%, after an incubation period of 3 min. In contrast, the extracts of control animals, fed with squid mantle, had the weakest antioxidant activity (4%). These data indicated that the presence of vitamin E in the diet can provide immediate protection against free radicals.

Mass transfer of cadmium ions in a hollow-fiber module by pertraction Marchese, Jose; Campderrós, Mercedes Edith The facilitated transport of Cd(II) ions through a hollow-fiber-supported liquid membrane with bis-2-ethylhexyl phosphoric acid as carrier was studied. The mass transfer rate, expressed as permeability P, was measured as a function of mean aqueous solution velocity and carrier concentration. Characteristic ion permeabilities of 10-26×10-7m/s were measured at feed velocities between 1×10-2-19×10-2 m/s at stripping velocities between 0.22×10-2-7×10-2 m/s with constant feed flow. The measured permeabilities were compared to generally accepted mass transfer correlations. The predicted permeabilities adequately fit the experimental data, indicating that the rate limiting step in the transport of the ion was the diffusion through both aqueous films, feed and stripping, whereas the organic resistance of the membrane was negligible. Furthermore, the proposed model allowed the prediction of the permeability of cadmium for different experimental conditions, which is useful to perform experiments to reduce metal levels in water or other effluents.

Diagnosis of Clostridium perfringens intestinal infections in sheep and goats Uzal, Francisco Alejandro Clostridium perfringens produces disease in sheep, goats and other animal species, most of which are generically called enterotoxemias. This micro-organism can be a normal inhabitant of the intestine of most animal species including humans, but when the intestinal environment is altered by sudden changes in diet or other factors, C. perfringens proliferates in large numbers and produces several potent toxins that are absorbed into the general circulation or act locally with usually devastating effects on the host. History, clinical signs and gross post-mortem findings are useful tools for establishing a presumptive diagnosis of enterotoxaemia by C. perfringens in sheep and goats, although no definitive diagnosis of these diseases can be made without laboratory confirmation. Because all types of C. perfringens can be normal inhabitants of the intestine of most animals, culture of this micro-organism from intestinal contents of animals has no diagnostic value unless a colony count is performed and large numbers (usually more than 104–107 CFU/g) of C. perfringens are found. The most accepted criterion in establishing a definitive diagnosis of enterotoxaemia by C. perfringens is the detection of its toxins in intestinal contents. However, some of the major toxins of C. perfringens (i.e. epsilon toxin) can also be found, albeit in small amounts, in the small intestine of clinically normal sheep, and this poses a diagnostic challenge. In such cases the histopathology of the brain must be used as an alternative diagnostic tool, since the lesions produced by epsilon toxin in the brains of sheep and goats are unique and pathognomonic for C. perfringens type D enterotoxaemia. Ancillary tests, such as measurement of urine glucose or observation of Gram stained smears of intestinal mucosa can be used and, although they have a presumptive diagnostic value when positive, they cannot be used to rule out a diagnosis of enterotoxaemia if they are negative. In conclusion, the diagnosis of C. perfringens infections in animals is complex and it is appropriate to rely on a combination of diagnostic techniques rather than one singe test.

Design for Operability: A Review of Approaches and Solution Strategies; Diseño para operabilidad: Una revisión de enfoques y estrategias de solución Blanco, Anibal Manuel; Bandoni, Jose Alberto In the last decades the chemical engineering scientific research community has largely addressed the design-foroperability problem. Such an interest responds to the fact that the operability quality of a process is determined by design, becoming evident the convenience of considering operability issues in early design stages rather than later when the impact of modifications is less effective and more expensive. The necessity of integrating design and operability is dictated by the increasing complexity of the processes as result of progressively stringent economic, quality, safety and environmental constraints. Although the design-for-operability problem concerns to practically every technical discipline, it has achieved a particular identity within the chemical engineering field due to the economic magnitude of the involved processes. The work on design and analysis for operability in chemical engineering is really vast and a complete review in terms of papers is beyond the scope of this contribution. Instead, two major approaches will be addressed and those papers that in our belief had the most significance to the development of the field will be described in some detail.; En las últimas décadas, la comunidad científica de ingeniería química ha abordado intensamente el problema de diseño-para-operabilidad. Tal interés responde al hecho de que la calidad operativa de un proceso esta determinada por diseño, resultando evidente la conveniencia de considerar aspectos operativos en las etapas tempranas del diseño y no luego, cuando el impacto de las modificaciones es menos efectivo y más costoso. La necesidad de integrar diseño y operabilidad esta dictada por la creciente complejidad de los procesos como resultado de las cada vez mayores restricciones económicas, de calidad de seguridad y medioambientales. Aunque el problema de diseño para operabilidad concierne a prácticamente toda disciplina, ha adquirido una identidad particular dentro de la ingeniería química debido a la magnitud económica de los procesos involucrados. El trabajo sobre diseño y análisis para operabilidad es realmente vasto y una revisión completa en términos de artículos supera los alcances de este trabajo. En su lugar, se discutirán los dos enfoques principales y aquellos artículos que en nuestra opinión han tenido mayor impacto para el desarrollo de la disciplina serán descriptos con cierto detalle.