Modeling of Phase and Chemical Equilibrium on the Quaternary System Acetic Acid, n-Butanol, Water and n-ButylAcetate Mandagaran, Beatriz Adriana; Campanella, Enrique Angel The correlation of the data for phase and chemical equilibrium in acetic acid-n-butanol-watern- butylacetate is presented. The azeotropic properties, the topological structure and the existence of a reactive azeotrope are discussed. The data are correlated by Hayden-O’Connell second virial coefficients and NRTL. Chemical equilibrium constant has a strong influence on the reactive azeotrope.

Boundary lipids in the nicotinic acetylcholine receptor microenvironment Barrantes, Francisco Jose; Bermudez, Vicente; Borroni, Maria Virginia; Antollini, Silvia Susana; Pediconi, Maria Filomena; Baier, Carlos Javier; Bonini, Ida Clara; Gallegos, Cristina Eugenia; Roccamo, Ana Maria; Valles, Ana Sofia; Ayala Peña, Victoria Belen; Kamerbeek, Constanza Belén The structural and functional properties of the nicotinic acetylcholine receptor (AChR), the archetype molecule in the superfamily of Cys-looped ligand-gated ion channels, are strongly dependent on the lipids in the vicinal microenvironment. The influence on receptor properties is mainly exerted by the AChR-vicinal (“shell” or “annular”) lipids, which occur in the liquid-ordered phase as opposed to the more disordered and “fluid” bulk membrane lipids. Fluorescence studies from our laboratory have identified discrete sites for fatty acids, phospholipids, and cholesterol on the AChR protein, and electron-spin resonance spectroscopy has enabled the establishment of the stoichiometry and selectivity of the shell lipid for the AChR and the disclosure of lipid sites in the AChR transmembrane region. Experimental evidence supports the notion that the interface between the protein moiety and the adjacent lipid shell is the locus of a variety of pharmacologically relevant processes, including the action of steroids and other lipids. I surmise that the outermost ring of M4 helices constitutes the boundary interface, most suitable to convey the signals from the lipid microenvironment to the rest of the transmembrane region, and to the channel inner ring in particular

Innovations in the development of healthier chicken sausages formulated with different lipid sources Andres, Silvina Cecilia; Zaritzky, Noemi Elisabet; Califano, Alicia Noemi Long chain polyunsaturated n-3 fatty acids (PUFA) are critical nutrients for human health and the fortification of foods with these fatty acids is an important emerging area from the commercial and academic point of view. Development, characterization and changes during refrigerated vacuum storage of low-fat chicken sausages formulated with pre-emulsified squid oil were examined and compared to those formulated with beef tallow. Physico chemical analysis and process yield after heat treatment were determined; the heat treated sausages were evaluated by purge loss, color, texture, microstructure by SEM, microbial counts, fatty acid profile, lipid oxidation and sensory analysis during refrigerated vacuum storage. Process yield of both formulations were higher than 97% and purge losses during storage lower than 7%. Purge losses of oil formulated sausages were lower than those with beef tallow. Sausages with squid oil resulted in higher lightness, lower redness and yellowness, and lower Texture Profile Analysis parameters than the formulation prepared with beef tallow. Microstructure of both formulations were similar, except for the fat droplets that microscopic observations showed in the sausages made with beef tallow. Low lipid oxidation was detected in formulation with squid oil due to the the combination of ingredients and storage conditions. Microbial counts of both products were less than 5 log CFU/g at the end of 90 days of storage. The sausage formulated with squid oil presented more than 30 and 40 g/100 g of monounsaturated and polyunsaturated fatty acids, respectively. Docosahexaenoic acid was the predominant polyunsaturated fatty acid, followed by eicosapentaenoic acid and linoleic acid. Both products showed safe sanitary conditions, good sensory acceptability and presented very good stability and quality attributes but sausages formulated with squid oil showed a better fatty acid profile according to nutritional criteria.

An efficient approach to homochiral indane nucleosides Ugliarolo, Esteban Ariel; Lantaño, Beatriz; Moltrasio, Graciela Yolanda; Moglioni, Albertina Gladys A series of new chiral 6-substituted purinyl and 8-aza-purinyl carbonucleosides based on indanol were synthesized from the commercially available (1R,2S)-1-amino-2-indanol and (1S,2R)-1-amino-2-indanol based on a well-known methodology.

La oposición argentina a la organización panamericana impulsada por Estados Unidos (Segunda Conferencia, México, 1901-1902) Morgenfeld, Leandro Ariel Este artículo analiza el enfrentamiento entre Argentina y Estados Unidos en la Segunda Conferencia Panamericana, realizada en México en 1901-1902. Es parte de una investigación más general, que estudia las tensiones argentino-estadounidenses en el ámbito interamericano durante las distintas conferencias que se realizaron entre 1889 y 1955. Con amplia documentación inédita de las cancillerías argentina y estadounidense, se analiza un capítulo fundamental del proceso panamericano en el que se expresaban las distintas visiones sobre la integración continental. Como en la Primera Conferencia Panamericana, la delegación argentina puso todo su empeño en dificultar en lo posible el avance de la organización impulsada por Estados Unidos.; This article analyzes the confrontation between Argentina and the United States in the Second Pan-American Conference that took place in Mexico between 1901 and 1902. Is part of a more general study about the ArgentineAmerican tensions during the different inter-american conferences between 1889 and 1955. Based on documents from the Argentine and the American Foreign Ministers that were not previously released, this work analyzes a fundamental chapter of the Pan-American process in which the different visions about continental integration were discussed. As they did in the First PanAmerican Conference, the Argentine delegation tried to prevent the progress of the organization driven by the United States.

ICTs in Latin America: An overview Santos, Rodrigo Martin In this paper, the state-of-the-art on the field of Information and Communications Technologies (ICTs) in Latin America is presented. Its main contribution consists in the localization of common objectives for the majority of the countries in the region. Although the countries are very heterogeneous from the cultural and geographical perspectives, there are many common factors that can be exploited in order to develop their economies. At first sight, Brazil or Mexico with their huge populations and big economies are giants compared to other countries like Bolivia or Costa Rica. However there are many common problems in all of them that can be addressed with a common strategy. An important question that this presentation tries to answer is the ICT profile of Latin America: consumer or producer. Data from the World Bank on ICT infrastructure and from the academic sector on the actual situation of the R&D activities in the region are analyzed to answer this question.

Early Cretaceous Radiolarians from southernmost Patagonia, Argentina; Radiolarios del Cretácico Temprano de la Patagonia Austral, Argentina Hollis, Chris; Archangelsky, Sergio; Cardenas, Orlando Se presenta una asociación de radiolarios hallada en el sector inferior de la Formación Río Mayer expuesta en la Estancia La Federica en la provincia Santa Cruz, Argentina. Los elementos dignósticos de valor bioestratigráfico indican una edad Berriasiano tardío-Barremiano temprano (Cretácico Temprano inicial) para este conjunto. Los radiolarios tienen afinidades faunísticas con asociaciones halladas costa afuera del noroeste de Australia y en el Pacífico occidental, al noreste de Nueva Zelanda. Se sugiere que la asociación de radiolarios patagónicos se desarrolló en aguas frías. Diez metros por debajo de los niveles portadores de radiolarios se hallan sedimentos continentales portadores de palinomorfos que fueron referidos a la Formación Springhill de edad BerriasianoValanginiano.; A radiolarian assemblage found in the lowermost strata of the Río Mayer Formation, as exposed at Estancia La Federica in Santa Cruz Province, Argentina, is described. The biostratigraphic markers of this assemblage indicate a late Berriasian-early Barremian age (early Early Cretaceous). The radiolarians have faunal affinities with early Cretaceous assemblages reported from offshore northwestern Australia and the western Pacific, northeast of New Zealand. A cool-water affinity is suggested for the Patagonian assemblage. Ten meters below the levels with radiolarians sediments bearing continental palynomorphs are found. They are referred to the Springhill Formation of Berriasian to Valanginian age.

Proteolytic activity of three probiotic strains in semi-hard cheese as single and mixed cultures: Lactobacillus acidophilus, Lactobacillus paracasei and Bifidobacterium lactis Bergamini, Carina Viviana; Hynes, Erica Rut; Palma, Susana Beatriz; Sabagg, Nora; Zalazar, Carlos Antonio The influence of three probiotic strains (Lactobacillus acidophilus, Lactobacillus paracasei and Bifidobacterium lactis) in semi-hard cheese proteolysis patterns was assessed. Probiotics were inoculated both as single cultures and as a three-strains mix, and added to milk by two different techniques: after a pre-incubation step or directly to vat. B. lactis did not show any effect on proteolysis of cheeses, while L. paracasei showed a little impact at the end of the ripening. On the contrary, L. acidophilus significantly influenced secondary proteolysis from the beginning of ripening, causing an increase in the levels of small nitrogen-containing compounds and free amino acids and changes in the peptide profiles. Lactobacillus acidophilus effect on peptidolysis was more noticeable when it was added to cheese-milk after pre-incubation in an enriched milk-fat substrate. Similar results obtained with the three-strain mixed culture suggest that L. acidophilus played a major role in secondary proteolysis of probiotic cheeses in this trial.

Estudio de la resistencia de fagos temperados de Lactobacillus delbrueckii a factores físicos de conservación e higiene Ebrecht, Ana Cristina; Guglielmotti, Daniela Marta; Reinheimer, Jorge Alberto; Capra, María Luján; Suárez, Viviana Beatriz Se estudió la viabilidad de dos fagos temperados de Lactobacillus delbrueckii subsp. lactis (Cb1/204 y Cb1/342) al pH, a diferentes temperaturas de conservación y a distintos tratamientos térmicos aplicados en la industria. Ambos fagos mantuvieron su nivel de recuento entre pH 4 y 9, hasta 30 min de exposición y el fago Cb1/342 mantuvo igual recuento aún a pH 3. A 4 ºC diminuyeron su recuento en 2 órdenes logarítmicos, mientras que a -80 ºC el fago Cb1/204 resultó levemente menos resistente. En leche, el tratamiento a 63 ºC no fue eficiente. A 72 ºC, el fago Cb1/204 resultó más resistente que el Cb1/342. A 82 ºC, ambos fagos fueron inactivados a los 2 min.

An elasto-visco-plastic model using the finite element method for crustal and lithospheric deformation Quinteros, Javier; Ramos, Victor Alberto; Jacovkis, Pablo Miguel A novel numerical model based on solid deformation is presented in this paper. This thermo-mechanical model can simulate the tectonic evolution of crust and (lithospheric and asthenospheric) mantle under different conditions. Our implementation uses the finite element method (FEM) in order to solve the equations. As a Lagrangian approach is employed, remeshing techniques are implemented to avoid distortion problems when a certain deformation threshold is reached. The translation of the state between the old and new mesh is achieved by means of the information stored on Lagrangian particles, which minimizes the diffusion. The model is able to represent elastic, viscous and plastic behaviour inside the studied domain. Three types of creep mechanism (diffusion, dislocation and Peierls) are included. Two different quadrilateral isoparametric elements were implemented and can be employed to perform the calculations. The first one is an element with 4 nodes, selective reduced integration and a stabilization operator to diminish hourglass modes, which reduces the computational time needed. The second one has 8 nodes located in standard positions, uses full integration scheme and has no hourglass modes as it satisfies the Inf-Sup condition. Several test cases with known solutions were run to validate the different aspects of the implementation.

Melampolides from Argentinean Acanthospermum australe Sánchez, Marianela; Kramer, Fernando Luis; Bargardi, Severino; Palermo, Jorge Alejandro The investigation of the ethanol extract of Acanthospermum australe, collected in the province of Misiones, Argentina, yielded eight melampolides (1-8) of the acanthospermal type. Two of them, 8β-hydroxy-9α-(2-methylbutyryloxy)-14-oxo-acanthospermolide (3) and 9α-hydroxy-8β-(2-methylbutyryloxy)-14-oxo-acanthospermolide (7) are new compounds. Two other compounds (4 and 8) have been previously reported, and the NMR data of 4 are corrected. Compounds 1, 2, 5 and 6 have not been previously reported, but are probably artifacts formed during extraction. Compounds 3, 6 and 7 showed slight antibiotic activity against Gram-positive bacteria.

Cost minimization in a non-catalytic biodiesel production plant Espinosa, Susana; Díaz, María Soledad; Brignole, Esteban Alberto In the present study, we propose an optimization model for the minimization of capital and operating costs in a supercritical methanol biodiesel plant, considering alternative process schemes together with the convenience or not to use a cosolvent in the chemical reaction. A rigorous process simulation model, based on a group contribution equation of state is integrated with a successive quadratic programming algorithm to solve the nonlinear problem. Optimization results show that noncatalytic biodiesel production with supercritical methanol can be economically competitive with conventional catalyzed production. © 2009 Elsevier B.V. All rights reserved.

A new colorimetric method for determination of alkylresorcinols in ground and whole-cereal grains using the diazonium salt Fast Blue RR Sampietro, Diego Alejandro; Vattuone, Marta Amelia; Catalan, Cesar Atilio Nazareno A fast and inexpensive method was developed to determine the content of alkylresorcinols (ARs) in ground and whole-cereal grains. This method is based on the ability of ARs to couple with Fast Blue RR salt in alkaline medium, yielding coloured azo-derivatives that can be quantified colorimetrically. Good linearity was observed for olivetol in the range of 1-10 μg with methanol as solvent (λmax = 480 nm) and 1-7 μg with butanol as solvent (λmax = 530 nm). Sensitivity obtained in butanol was comparable to that obtained in the Fast Blue B based method (methanol as solvent, λmax = 520 nm). In the new colorimetric method described here, incubation time was reduced to 20 min and the stability of the reaction products was as long as 3 h. The method appears promising for the analysis of 1,3-dihydroxybenzene derivatives in samples from plant breeding and food analyses.

First record of scelidodon chiliense (LYDEKKER) (Phyllophaga, Scelidotheriinae) from the lujanian stage (Late Pleistocene Early Holocene) of Argentina Miño Boilini, Ángel Ramón; Carlini, Alfredo Armando; Chiesa, Jorge Orlando; Lucero, Natalia Paola; Zurita, Alfredo Eduardo The Scelidotheriinae constitutes a group of sloth with numerous problematics, mainly related to their origin and phylogenetic relationships. This subfamily is principally characterized by a narrow and elongated skull, a coincident modification of the dental series and having a medium size. It is reported the first record of Scelidodon chiliense (LYDEKKER) (Phyllophaga, Scelidodieriinae), exhumed from Lujanian sediments (Late Pleistocene - Early Holocene) belonging to the Uspara Formation of San Luis Province (Argentina). The fossil (MHIN-UNSL GEO V-199) consists of a sub-complete skull without teeth, except the right Ml. The specific assignation is mainly based on: sagittal and temporal crests with little development and parietal and squamosal bones separated by an horizontal suture. This reports broad the geographical distribution of the species, known so far only for northern Chile, Bolivia, Peru and Ecuador. Finally, it allows raising and discussing some hypothesis related to its presence into the current territory of Argentina.

Geastrum episcopale: a new noticeable species with red-violet exoperidium Kuhar, José Francisco; Papinutti, Víctor Leandro A new species, Geastrum episcopale, is described from Argentina. Detailed descriptions and illustrations of fresh and dry basidiomata are provided along with photographs of microscopic elements, such as spores, capillitium, calcium oxalate crystals, and exo- and endoperidium surfaces. This fungus is typical of the genus in its morphology and ecology but clearly differs from every known species. This species can be distinguished easily by the red-violet (to magenta) exoperidium and the lilac endoperidium. Specimens were collected on wet soil composed of a superficial layer of ca. 5 cm leaf litter and 15 cm of particulate and melanized lignocellulosic material (pH 6.5) under Eugenia uruguayensis and Nectandra sp.

La temperatura como principal determinante de la germinación en especies del Chaco seco de Argentina; Temperature as a main factor determining germination in Argentinean dry Chaco species Funes, Guillermo; Díaz, Sandra Myrna; Venier, Maria Paula La composición de especies vegetales de una región es el resultado de procesos que operan a distintas escalas espaciales y temporales. Las especies que conviven en una comunidad perciben una serie de factores ambientales que condicionan el período del año para la germinación y emergencia que maximiza el establecimiento y supervivencia de los individuos. En este trabajo estudiamos cómo la temperatura y la luz afectan la germinación de semillas de un grupo de especies comunes en los bosques chaqueños del centro de la Argentina. Se seleccionaron 25 especies de angiospermas que abarcan un espectro amplio de formas de vida. Se llevaron a cabo experimentos de germinación bajo tres regímenes de temperatura (15/ 5 ºC, 25/15 ºC y 35/20 ºC), bajo luz (12/ 12 h luz/sombra) y oscuridad permanente. La temperatura fue el principal factor regulador del proceso de germinación en las especies estudiadas. En general las semillas de las diferentes especies fueron indiferentes a la luz. Los patrones observados en este estudio apoyan la idea de que la germinación se asocia con las temperaturas del momento del año en el que se concentran las precipitaciones, y que en estos sistemas de precipitación fuertemente estacional la luz no sería un factor determinante en el proceso de germinación.; Temperature is a main factor determining germination in Chaco woodland species. Plant species composition is the result of processes that operate at different spatial and temporal scales. Species that coexist in a community are affected by environmental factors that influence the periods of the year when seed germination and seedling emergence occur, thus maximising establishment and survival. In this study we investigated the effects of temperature and light on seed germination of a wide range of plant species common in the Chaco woodlands of central Argentina. Twenty five species of angiosperms were selected, covering a wide range of life forms. Experimental treatments were three temperature regimes (15/5 °C, 25/15 °C and 35/20 °C) in light (12/12 h daily photoperiod) and in continuous darkness. Temperature was the main factor triggering the germination and most species were indifferent to light. Our results support the idea that seed germination is associated with the highly seasonal nature of rainfall in this region.

Importadora electrónica: an argentine company with more than fifty years buying and selling electron tubes Santoro, Abel Reinaldo Describe una empresa de fabricación de válvulas.

Renta básica: ¿una herramienta para satisfacer deberes humanitarios, de justicia o de legitimidad?; Basic income: A means to satisfy humanitarian, justice or legitimacy duties? Seleme, Hugo Omar El objetivo del presente trabajo es mostrar que en circunstancias de ilegitimidad política utilizar la herramienta de la renta básica como un medio para satisfacer deberes humanitarios o de justicia distributiva se encuentra injustificado. La hipótesis que defenderé es que, en tales circunstancias, la renta básica debe ser utilizada para garantizar la posibilidad efectiva de participación política. Adicionalmente, esta justificación de la renta básica nos permite enfrentar una de las objeciones más poderosa que ha recibido, su aparente violación del principio de reciprocidad.; The objective of the present work is to show that in circumstances of political illegitimacy using the basic income device as a means to satisfy humanitarian or distributive justice duties is unjustified. The hypothesis I shall defend is that, in such circumstances, the basic income should be used to guarantee the effective possibility of political participation. Additionally, that justification of the basic income enables us to face one of the most powerful objections the basic income has received, its apparent violation of the reciprocity principle.

Measurement of charge distribution in actin bundles by surface potential microscopy Zhang, Peng; Cantiello, Horacio Fabio Bundles of filamentous actin (F-actin) deposited on a gold-plated surface were concurrently imaged using atomic force microscopy (AFM) and surface potential microscopy (SPM). The surface potential was mapped as a function of tip distance to surface using a constant bias potential. There was an uneven spatial distribution of charges detected by SPM, consistent with the segmented topological features shown by AFM of the actin bundles. SPM analysis showed localized changes in surface potential between the axial and transversal sections of the bundles, which are consistent with nonuniform charge distributions of adsorbed salt ions on F-actin.

Boron biodistribution study in colorectal liver metastases patients in Argentina Cardoso Cúneo, Jorge Eduardo Carlos; Nievas, S.; Pereira, M.; Schwint, Amanda Elena; Trivillin, Verónica Andrea; Pozzi, Emiliano César Cayetano; Heber, Elisa Mercedes; Monti Hughes, Andrea; Sanchez, P.; Bumaschny, E.; Itoiz, María Elina; Liberman, Susana Alcira Ex-situ BNCT for multifocal unresectable liver metastases employing whole or partial autograft techniques requires knowledge of boron concentrations in healthy liver and metastases following perfusion and immersion in Wisconsin solution (W), the procedure employed for organ preservation during ex-situ irradiation. Measurements of boron concentration in blood, liver and metastases following an intravenous infusion of BPA-F in five colorectal liver metastases patients scheduled for surgery were performed. Tissue samples were evaluated for boron content pre and post perfusion and immersion in W. Complementary histological studies were performed. The data showed a dose-dependent BPA uptake in liver, a boron concentration ratio liver/blood close to 1 and a wide spread in the metastases/liver concentration ratios in the range 0.8-3.6, partially attributable to histological variations between samples. Based on the boron concentrations and dose considerations (liver < or =15 Gy-Eq and tumor> or =40 Gy-Eq) at the RA-3 thermal neutron facility (mean flux of about (6+/-1) x 10(9) n cm(-2)s(-1)), ex-situ treatment of liver metastases at RA-3 would be feasible.