Two-phase flow instabilities: A review Ruspini, Leonardo; Marcel, Christian Pablo; Clausse, Alejandro An updated review of two-phase flow instabilities including experimental and analytical results regarding density-wave and pressure-drop oscillations, as well as Ledinegg excursions, is presented. The latest findings about the main mechanisms involved in the occurrence of these phenomena are introduced. This work complements previous reviews, putting all two-phase flow instabilities in the same context and updating the information including coherently the data accumulated in recent years. The review is concluded with a discussion of the current research state and recommendations for future works.

Electrode/Electrolyte Interphase Studies of Ceria Based Electrolytes for IT-SOFCs Baque, Laura Cecilia; Padmasree, Karinjilottu; Fuentes, Antonio F.; Serquis, Adriana Cristina; Soldati, Analía Leticia Solid oxide fuel cells (SOFCs) require high operation temperatures (up to 800°C) in order to allow oxygen ion conduction through the ceramic electrolyte. Lowering SOFC operation temperature implies enhancing the transport and electrochemical properties of both electrolyte and cathode. In this work, the electrochemical performance of nanostructured La0.4Sr0.6Co0.8Fe0.2O3-d (LSCFO)/Ce0.8Gd0.2O2-d(CGO)/LSCFO and LSCFO/Ce0.8Nd0.2O2-d (CNO)/LSCFO symmetrical cells was investigated. The bulk conductivity is similar for both electrolytes, while the grain boundary and total conductivities is higher for the CGO electrolyte. Nevertheless, CGO electrolyte exhibits large pores that compromise its mechanical properties. In addition, cathode performance degrades in LSCFO/CGO/LSCFO cells.

Direct recoil spectroscopy of adsorbed atoms and self-assembled monolayers on Cu(001) Salazar Alarcón, Leonardo; Jia, J.; Carrera, Alvaro Daniel; Esaulov, V. A.; Ascolani, Hugo del Lujan; Gayone, Julio Esteban; Sánchez, Esteban Alejandro; Grizzi, Oscar We present results of adsorption experiments of Sn and 1,4-benzenedimethanethiol (BDMT) on Cu(001), which illustrate the capabilities of a new setup specifically designed to perform surface studies by Direct Recoil Spectroscopy (DRS). The system consists of three UHV chambers connected in series with a 1–100 keV ion accelerator. In the main UHV chamber the DRS technique is combined with other more standard techniques such as Auger and Energy Loss Electron Spectroscopy, and Low Energy Electron Diffraction. The capabilities of the instrument are exemplified by two adsorption studies on the (001) face of Cu. First we describe measurements for 0.5 monolayer of Sn adsorbed on Cu that are in agreement with the crystallographic symmetry (3√2x√2) R45° seen by LEED and the appearance of Cu vacancies along the [100] direction. Then we present a study of self-assembling of 1,4-benzenedimethanethiol (BDMT) on Cu(001) from the vapour phase. For this system we show that it is possible to form a standing-up phase at large exposures, of the order of 106 L, and discuss its stability with temperature. We also discuss a S enrichment effect induced during the first adsorption stages of BDMT.

On the relation between Seyfert 2 accretion rate and environment at z < 0.1 Coldwell Lloveras, Georgina Vanesa; Gurovich, Sebastian; Diaz Tello, Jorge Andres; Söchting, Ilona K.; Garcia Lambas, Diego Rodolfo We analyse different properties of the small-scale environment of Seyfert 2 for two samples selected according to the accretion rate parameter, R, from the Sloan Digital Sky Survey, Data Release 7 survey. We compare the results with two control samples of non-active galaxies that cover the same redshift range, luminosity, colours, morphology, age and stellar mass content. Our study shows that both high and low accretion rate subsamples reside in bluer and lower density environments than the control samples. However, we find that this difference is at least two times stronger for the low accretion rate Seyferts. In the vicinity of Seyfert 2, red galaxies have systematically lower values of stellar mass as compared with corresponding control samples. The lower values of stellar mass for red neighbours is more significant at higher density environments and it is more evident for low accretion rate Seyfert. We also find that this effect is independent of the host's stellar mass. Our results are consistent with a scenario where active galactic nucleus occurrence is higher in lower/medium density environments with a higher merger rate and a lack of a dense intergalactic medium (that can strip gas from these systems) that provide suitable conditions for the central black hole feeding. We find this particularly evident for the low accretion rate Seyferts that could compensate through the intergalactic medium the lack of gas of their hosts.

Mercado de trabajo y trayectorias laborales en contextos de pobreza. Desafíos para pensar la política social; Labour Market and Career Paths in Contexts of Poverty. Challenges for Social Policy Freyre, Maria Laura El presente artículo analiza las principales características del mercado de trabajo en Argentina desde las recientes transformaciones neoliberales y específicamente tras la caída del régimen de Convertibilidad con el objetivo de considerar sus efectos diferenciales sobre los hogares de menores recursos. A partir de este diagnóstico se propone reflexionar sobre los desafíos que suponen las características de la fuerza de trabajo presente en las familias pobres, para el diseño e implementación de la política social de empleo y sostenimiento de ingresos.; Recent research on the labor market in Argentina highlights the positive effects of the recovery phase and initiated economic growth from 2003 to 2009. The specific literature on the subject point emphasizes the context of overall economic recovery after the crisis and devaluation of 2001-2002, both in terms of growth in economic activity, measured from GDP growth, as the conditions in the labor market due to the sustained recovery in employment levels and progressive restructuring of labor income. In this phase of economic expansion, there was a reduction in labor costs. This paper analyzes the main features of the labor market in Argentina since the recent neoliberal transformations and specifically after the collapse of the Convertibility regime in order to consider their differential effects on low-income households. From this analysis it intends to reflect on the challenges of the features of the present workforce in poor families, for the design and implementation of social policy and employment income support.

Assessing the reliability of friends-of-friends groups on the future Javalambre Physics of the Accelerating Universe Astrophysical Survey Zandivarez, Arnaldo Ariel; Diaz, Maria Eugenia; Oliveira, Claudia Mendes de; Ascaso, B.; Benítez, N.; Dupke, R.; Sodré, L.; Irwin, J. Aims: We have performed a detailed analysis of the ability of the friends-of-friends algorithm to identify real galaxy systems in deep surveys such as the future Javalambre Physics of the Accelerating Universe Astrophysical Survey. Our approach was twofold: assessing the reliability of the algorithm in real and in redshift space. In the latter, our intention was also to determine the degree of accuracy that could be achieved when using spectroscopic or photometric-redshift determinations as a distance indicator. Methods: We built a light-cone mock catalogue using synthetic galaxies constructed from the Millennium Run Simulation I plus a semi-analytical model of galaxy formation. We explored different ways to define the proper linking length parameters of the algorithm to identify the best-suited galaxy groups in each case. Results: We found that when one identifies systems in redshift space using spectroscopic information, the linking lengths should take into account the variation of the luminosity function with redshift as well as the linear redshift dependence of the radial fiducial velocity in the line-of-sight direction. When we tested the purity and completeness of the group samples, we found that the best resulting group sample reaches values of ~40% and ~70% of systems with high levels of purity and completeness, when spectroscopic information was used. To identify systems using photometric redshifts, we adopted a probabilistic approach to link galaxies in the line-of-sight direction. Our result suggests that it is possible to identify a sample of groups with fewer than ~40% false identifications at the same time as we recover around 60% of the true groups. Conclusions: This modified version of the algorithm can be applied to deep surveys provided that the linking lengths are selected appropriately for the science to be made with the data.

Central α- and β-thujone: Similar anxiogenic-like effects and differential modulation on GABAA receptors in neonatal chicks Rivera, E. M.; Cid, Mariana Paula; Zunino, María Paula; Baiardi, Gustavo Carlos; Salvatierra, Nancy Alicia The convulsant effects of α-thujone are attributed to inhibitory actions on the GABAA receptor. We investigated, for the first time, the effects of α-thujone or β-thujone administrated centrally on the fear/anxiety behaviour of 3-day-old chicks in an Open Field and their modulation on the GABAA receptor. Higher doses were convulsant by eliciting a toxic and excitatory action, with the results showing that a dose of 78 nmol of either of the two diastereoisomers had an anxiogenic-like effect observed as an increased latency to ambulate and a reduced locomotor activity in an Open Field. Nevertheless, only the central administration of α-thujone reversed the increase induced by acute stress in the flunitrazepam-sensitive GABAA receptor recruitment. These findings demonstrated that α-thujone, when intracerebroventricularly administered, suppressed the GABAA receptor recruitment induced by acute stress, maybe due to α-thujone blocking the benzodiazepine binding site or another site of the GABAA complex. However, it should not be discarded that acute stress associated with novelty may have induced the recruitment of a subpopulation of GABAA receptors more sensitive to α-thujone than to the constitutive receptors, or that this monoterpene could have inhibited any protein or enzyme trafficking that modulated the phosphorylation of the receptor involved in the turnover of GABAA receptor. β-Thujone showed behavioural effects similar to its diastereoisomer α-thujone. However, its action mechanism may have been mediated by other neurotransmitter systems, such as the serotonergic one or by a different biological effectiveness due to a distinct stereochemistry at the specific site of the GABAA receptor.

β3-Chimaerin, a novel member of the chimaerin Rac-GAP family Zubeldia Brenner, Lautaro; Gutierrez Uzquiza, Alvaro; Barrio Real, Laura; Wang, Hongbin; Kazanietz, Marcelo Gabriel; Coluccio Leskow, Federico Chimaerins are a family of diacylglycerol- and phorbol ester-regulated GTPase activating proteins (GAPs) for the small G-protein Rac. Extensive evidence indicates that these proteins play important roles in development, axon guidance, metabolism, cell motility, and T cell activation. Four isoforms have been reported to-date, which are products of CHN1 (α1- and α2-chimaerins) and CHN2 (β1- and β2-chimaerins) genes. Although these gene products are assumed to be generated by alternative splicing, bioinformatics analysis of the CHN2 gene revealed that β1- and β2-chimaerins are the products of alternative transcription start sites (TSSs) in different promoter regions. Furthermore, we found an additional TSS in CHN2 gene that leads to a novel product, which we named β3-chimaerin. Expression profile analysis revealed predominantly low levels for the β3-chimaerin transcript, with higher expression levels in epididymis, plasma blood leucocytes, spleen, thymus, as well as various areas of the brain. In addition to the prototypical SH2, C1, and Rac-GAP domains, β3-chimaerin has a unique N-terminal domain. Studies in cells established that β3-chimaerin has Rac-GAP activity and is responsive to phorbol esters. The enhanced responsiveness of β3-chimaerin for phorbol ester-induced translocation relative to β2-chimaerin suggests differential ligand accessibility to the C1 domain.

Simulations of cold nuclear matter at sub-saturation densities Giménez Molinelli, Pedro Agustín; Nichols, Juan Ignacio; Lopez, J. A.; Dorso, Claudio Oscar Ideal nuclear matter is expected to undergo a first order phase transition at the thermodynamic limit. At such phase transitions the size of density fluctuations (bubbles or droplets) scale with the size of the system. This means that simulations of nuclear matter at sub-saturation densities will inexorably suffer from what is vaguely referred to as “finite size effects”. It is usually thought that these finite size effects can be diminished by imposing periodic boundary conditions and making the system large enough, but as we show in this work, that is actually not the case at sub-saturation densities. In this paper we analyze the equilibrium configurations of molecular dynamics simulations of a classical model for symmetric ideal (uncharged) nuclear matter at sub-saturation densities and low temperatures, where phase coexistence is expected at the thermodynamic limit. We show that the most stable configurations in this density range are almost completely determined by artificial aspects of the simulations (i.e. boundary conditions) and can be predicted analytically by surface minimization. This result is very general and is shown to hold true for several well known semi-classical models of nuclear interaction and even for a simple Lennard-Jones potential. Also, in the limit of very large systems, when “small size” effects can be neglected, those equilibrium configurations seem to be restricted to a few structures reminiscent to the “Pasta Phases” expected in Neutron Star matter, but arising from a completely different origin: In Neutron Star matter, the non-homogeneous structures arise from a competition between nuclear and Coulomb interactions while for ideal nuclear matter they emerge from finite (yet not “small”) size effects. The role of periodic boundary conditions and finite size effects in Neutron Star matter simulations are reexamined.

Insects found in birds’ nests from Argentina. Pseudoseisura lophotes Reichenbach, 1853 and Anumbius annumbi (Vieillot, 1817) (Aves: Furnariidae), hosts of Triatoma platensis Neiva, 1913 (Hemiptera: Reduviidae: Triatominae) Turienzo, Paola Noemí; Di Iorio, Osvaldo Rubén The insect fauna of the nests of Pseudoseisura lophotes (Reichenbach, 1853) (Aves: Furnariidae) from Argentina was investigated. A total of 110 species (68 identified to species, 22 identified to genus, 20 identified to family) in 40 families of 10 orders of insects was found in these nests. Triatoma platensis Neiva, 1913 (Hemiptera: Reduviidae) was found again in nests of P. lophotes, corroborating after 73 years the first observations made by Mazza in 1936. The occurrence of the insects in nests of P. lophotes is compared with the previously known insect fauna in nests of A. annumbi, Furnarius rufus (Furnariidae), and Myiopsitta monachus (Psittacidae). The insect fauna in additional nests of Anumbius annumbi from the same and/or different localities is given, and used in comparisons. The first occurrence of Cuterebridae (Diptera) in birds’ nests, their pupae as the overwintering stage, and the second simultaneous infestation by two species of Philornis (Diptera: Muscidae) on the same nestlings are presented. Other simultaneous infestations of different hematophagous arthropods (Hemiptera: Cimidae; Reduviidae: Triatominae, and Acari: Argasidae) are remarked and discussed.

Screen-printed electrodes for electroanalytical sensing, of chromium VI in strong acid media Miscoria, Silvia Alejandra; Jacq, C.; Maeder, T.; Negri, Ricardo Martin Simple, low-cost and acid-resistant carbon-based screen-printed electrodes (SPEs) addressed to detection of hexavalent chromium species, Cr(VI), in sulfuric acid at pH about 1, were prepared and characterized. Working and counter electrodes were prepared jointly on the same substrate in a single strip (working-counter electrodes pair). The batch printing process allowed obtaining many working-counter electrode pairs in a unique step. The developed working electrodes are comprised of several layers deposited on an alumina substrate: (1) bottom silver conductor, (2) dense organic–graphite composite conductor, (3) active layer consisting of a porous organic–graphite composite which contains a Cr(III) ionophore for testing Cr(III) obtained after reducing Cr(VI), and (4) an insulating and protective dielectric. All materials except the bottom Ag conductor were made on an organic matrix based on a thermoplastic polymer, polyvinylbutyral (PVB). The amperometric determination of Cr(VI) species at pH 1 was performed over a wide concentration range (dynamic range 3 μM–40 mM). The range for linear amperometric response is 3 μM–10 mM, with sensitivity about 0.08 mA mM−1. The sensitivity is improved in comparison with previously developed sensors, while keeping a low limit of detection (LOD about 1 μM). The response of the sensors are not interfered by the presence of Cr(III) in the solution, although the sensor can detect local formation of Cr(III) at the electrode surface after the reduction of Cr(VI) when diethylenetriamine-pentaacetic acid (DTPA), a complexing agent for Cr(III) is incorporated into the pastes.

Protein Antigens Increase the Protective Efficacy of a Capsule-Based Vaccine against Staphylococcus aureus in a Rat Model of Osteomyelitis Lattar, Santiago Martín; Noto Llana, Mariangeles; Denoël, Philippe; Germain, Sophie; Buzzola, Fernanda Roxana; Lee, Jean C.; Sordelli, Daniel Oscar Staphylococcus aureus is an invasive bacterial pathogen, and antibiotic resistance has impeded adequate control of infections caused by this microbe. Moreover, efforts to prevent human infections with single-component S. aureus vaccines have failed. In this study, we evaluated the protective efficacy in rats of vaccines containing both S. aureus capsular polysaccharides (CPs) and proteins. The serotypes 5 CP (CP5) and 8 CP (CP8) were conjugated to tetanus toxoid and administered to rats alone or together with domain A of clumping factor A (ClfA) or genetically detoxified alpha-toxin (dHla). The vaccines were delivered according to a preventive or a therapeutic regimen, and their protective efficacy was evaluated in a rat model of osteomyelitis. Addition of dHla (but not ClfA) to the CP5 or CP8 vaccine induced reductions in bacterial load and bone morphological changes compared with immunization with either conjugate vaccine alone. Both the prophylactic and therapeutic regimens were protective. Immunization with dHla together with a pneumococcal conjugate vaccine used as a control did not reduce staphylococcal osteomyelitis. The emergence of unencapsulated or small-colony variants during infection was negligible and similar for all of the vaccine groups. In conclusion, addition of dHla to a CP5 or CP8 conjugate vaccine enhanced its efficacy against S. aureus osteomyelitis, indicating that the inclusion of multiple antigens will likely enhance the efficacy of vaccines against both chronic and acute forms of staphylococcal disease.

Core promoter: A critical region where the hepatitis B virus makes decisions Quarleri, Jorge Fabian The core promoter (CP) of the viral genome plays an important role for hepatitis B virus (HBV) replication as it directs initiation of transcription for the synthesis of both the precore and pregenomic (pg) RNAs. The CP consists of the upper regulatory region and the basal core promoter (BCP). The CP overlaps with the 3’-end of the X open reading frames and the 5’-end of the precore region, and contains cis-acting elements that can independently direct transcription of the precore mRNA and pgRNA. Its transcription regulation is under strict control of viral and cellular factors. Even though this regulatory region exhibits high sequence conservation, when variations appear, they may contribute to the persistence of HBV within the host, leading to chronic infection and cirrhosis, and eventually, hepatocellular carcinoma. Among CP sequence variations, those occurring at BCP may dysregulate viral gene expression with emphasis in the hepatitis B e antigen, and contribute to disease progression. In this review these molecular aspects and pathologic topics of core promoter are deeply evaluated.

Density Functional Theory study of the hydrogen storage in a vacancy zone of an iron-nickel cell Canto, G.; Salazar Ehuan, I.; González Sánchez, J.; Tapia, A.; Quijano, R.; Simonetti, Sandra Isabel Calculations using the SIESTA code have been performed to study the location of one and two hydrogens in a vacancy zone of a Fe50Ni50 cell. H debilitates the original metal–metal bonds by forming strong interactions with the metallic matrix. The Fe–H interaction is stronger than the Ni–H interaction. The H–metal exchange contributes to this process. After first H atom adsorption, the strength of the nearest Fe–Fe, Fe–Ni and Ni–Ni bonds decreases to about 89%, 15% and 1%, respectively. Then, the Fe–Fe bond is the most affected. The adsorption of an additional H atom modified the metal–metal strength in a lesser percent. Then, no additional decohesion is observed in the metallic bonds when two H atoms are present but in this case more metallic bonds are affected. The H–H interaction is small; an H2 molecule is not formed in the vacancy zone of the Fe50Ni50 cell.

Crisis y venta de grandes empresas en Argentina en los años noventa: el caso de Alpargatas; Crisis and Sale of Large Companies in Argentina in the 90s: the Alpargatas Case; Crise et vente de grandes entreprises en argentine dans les années 1990: le cas de Alpargatas; Crise e venda de grandes empresas na argentina nos anos noventa: o caso de Alpargatas Perez Artica, Rodrigo Un intenso proceso de extranjerización de grandes empresas ha tenido lugar en Argentina desde 1990. Este artículo analiza el caso de la desnacionalización de la empresa Alpargatas, ocurrida en 1999. se concluye que la interrupción en el acceso a crédito local e internacional, la recesión doméstica e internacional y la agudización de la competencia en los años finales de la década cumplieron un papel determinante en la extranjerización. Las ventajas comerciales y financieras con que dicha firma contó al principio de la década no alcanzaron para evitar su crisis.; A sharp process of denationalization of large firms has taken place in Argentina since 1990. This paper analyses the case of the denationalization of the firm Alpargatas, occurred in 1999. It concludes that the interruption of access to foreign and domestic credit, the local economic recession and the exacerbation of competence that occurred in the final years of the decade, played a key role in determining the lost of national control over the firm. The commercial and financial advantages that the firm exerted at the beginning of the decade were not enough to avoid its crisis.; Un intense processus de dénationalisation (dans le sens de passé en mains étrangères) des grandes entreprises a eu lieu en Argentine depuis 1990. Cet article analyse le cas de la dénationalisation (en 1999) de l'entreprise Alpargatas. Nous concluons que l'interruption de l'accés au crédit local et international, la récession domestique et internationale et l'intensification de la concurrence à la fin de cette décennie ont joué un rôle décisif pour la dénationalisation. Les avantages commerciaux et financiers dont cette firme avait bénéficié au début de la décennie n'ont pas suffi pour lui éviter la crise.; Um intenso processo de "estrangeirização" de grandes empresas aconteceu na Argentina desde 1990. Este artigo analisa o caso da desnacionalização da empresa Alpargatas, ocorrida em 1999. Conclui-se que a interrupção no acesso a crédito local e internacional, a recessão interna e internacional e o aprofundamento da competência nos anos finais da década tiveram um papel determinante na "estrangeirização". As vantagens comerciais e financeiras com que essa firma contou no início da década não foram suficientes para evitar a sua crise.

Discursos de lo social en problemáticas ambientales: Agua y minería en el centro-oeste argentino Saldi, Leticia; Wagner, Lucrecia Soledad; Escolar, Diego Since the nineteenth century, in the province of Mendoza (Argentina) state policies favored the centralization and distribution of water to benefit  irrigation oasis and the wine industry, controlled by the political elite and European immigrants. Such distribution was legitimized by arguments that posited an environmental rationality supposedly scientific and universal care associated subsequent water and nature.Since the recent conflict megamineros project installation would be sources of exploitation and water pollution on a large scale, we analyze the state conceptions of socio-environmental relations, contradictions and political effects on both social distribution of resources and in environmental configuration itself. We conclude that the State Mendoza challenges the nature according to their potential exchange value, under the rhetorical appeal to technical efficiency, development, modernization and consensus at the expense of social and cultural rights.; En la provincia de Mendoza (Argentina) las políticas estatales favorecieron desde el siglo XIX la centralización y distribución de agua en beneficio de los oasis de riego y la actividad vitivinícola, controlada por la elite política e inmigrantes europeos. Tal distribución fue legitimada por argumentos que postularon una racionalidad ambiental supuestamente científica y universal, ulteriormente asociada al cuidado del agua y la naturaleza. A partir del reciente conflicto por la instalación de proyectos megamineros que serían fuentes de explotación y contaminación del agua en gran escala, analizamos las concepciones estatales sobre las relaciones socio-ambientales, sus contradicciones y efectos tanto en las políticas de distribución social de recursos como en la propia configuración ambiental. Concluimos que el Estado mendocino interpela a la naturaleza según su potencial valor de cambio, bajo la apelación retórica a la eficiencia técnica, el desarrollo, la modernización y el consenso, en detrimento de derechos sociales y culturales.

Assessing degradation of abandoned farmlands for conservation of the monte desert biome in Argentina Yanelli, Florencia A.; Tabeni, Maria Solana; Mastrantonio, Leandro Eloy; Vezzani, Nazareth Land abandonment is a major issue worldwide. In Argentina, the Monte Desert is the most arid rangeland, where the traditional conservation practices are based on successional management of areas excluded to disturbances or abandoned. Some areas subjected to this kind of management may be too degraded, and thus require active restoration. Therefore, the aim of this study was to assess whether passive succession-based management is a suitable approach by evaluating the status of land degradation in a protected area after 17–41 years of farming abandonment. Soil traits and plant growth forms were quantified and compared between sites according to time since abandonment and former land use (cultivation and grazing). Two variables were calculated using the CORINE-CEC method, i.e., potential (PSER) and actual (ASER) soil erosion risk. PSER indicates the erosion risk when no vegetation is present, while ASER includes the protective role of vegetation cover. Results showed that land use history had no significant effect on plant growth forms or soil traits (p > 0.05). After more than 25 years since abandonment of farming activities, soil conditions and vegetation cover had improved, thus having a lower ASER. Nevertheless, the present soil physical crusts may have delayed the full development of vegetation, enhancing erosion processes. Overall, this study indicates that succession-based management may not be the best practice in terms of conservation. Therefore, any effort for conservation in the Monte Desert should contemplate the current status of land degradation and potential vegetation recovery.

Prey composition of Peregrine Falcons (Falco peregrinus cassini) preying upon a mixed-species seabird colony in Argentine Patagonia; Composición de la dieta de Halcones Peregrinos (Falco peregrinus cassini) depredando en una colonia mixta de aves marinas en la Patagonia Argentina García, Germán Oscar; Bó, Maria Susana; Yorio, Pablo Martin Predation is one of the main factors determining breeding strategies in many seabird species (Lack 1968, Burger & Gochfeld 1994, Gaston 2004). Among avian predators, raptors such as eagles, owls and falcons regularly prey on seabird adults and offspring (Paine et al. 1990, Holt 1994, Hayward et al. 2010). The Peregrine Falcon (Falco peregrinus) has a cosmopolitan distribution (White et al. 2002), and is regularly found along coastal areas of Argentine Patagonia which are characterized by large seabird breeding assemblages (Yorio et al. 1999). Peregrine Falcons from coastal populations in the Northern Hemisphere have been shown to be important predators of seabirds (Ratcliffe 1980, Paine et al. 1990, Velarde 1993), but very little is known on the contribution of seabird prey to Peregrine Falcon diet in coastal Argentina. Few studies have quantified their diet in Patagonia, and they indicate that prey composition may vary depending on location (Ellis et al. 2002, Santillán et al. 2010). Our goal was to determine the prey composition and contribution of seabirds to the diet of a pair of Peregrine Falcons breeding near a mixed-species seabird colony on the coast of Argentine Patagonia.

Preparation and characterization of polymorphs of the glucocorticoid deflazacort Kassuha, Diego Enrique; Aiassa, Virginia; Bruno, Flavia Paola; Cuadra, Gabriel R.; Sperandeo, Norma Rebeca The polymorphism of new and old active pharmaceutical ingredients (APIs) is of great importance due to performance, stability and processability aspects. The objective of this study was to investigate the polymorphism of deflazacort (DEF), a glucocorticoid discovered >40 years ago, since this phenomenon has not been previously investigated for this API. Using different methods for solid form screening, it was determined for the first time that DEF is able to exist as three forms: a crystalline (DEF-1); a hydrated X-ray amorphous (DEF-t-bw) and an anhydrous amorphous phase (DEF-g) obtained from manually grinding DEF-1. The in vitro and in vivo dissolution rates (DRs) of DEF-1 and DEF-t-bw, which were measured using the rotating disk method in water at 37 °C and the pellet implantation technique in rats, respectively, indicated that DEF-t-bw exhibited slightly faster in vitro and in vivo DRs than those of the crystalline form, but the values were not significantly different. In addition, it was determined that DEF-t-bw devitrifies to DEF-1 by the effect of pressure, humidity and heat. It was concluded that DEF is glucorticoid with low tendency to exhibit different crystalline forms and that DEF-t-bw has no advantages over DEF-1 in terms of solubility, DRs and solid-state stability.

Rheological and barrier properties of nanocomposites of HDPE and exfoliated Montmorillonite Horst, María Fernanda; Quinzani, Lidia Maria; Failla, Marcelo Daniel Polyethylene (PE) / clay nanocomposites were prepared by melt mixing using polyethylene grafted with maleic anhydride (PEg) as compatibilizer. Concentrations between 2 and 15 wt% of an organophilic montmorillonite (MMT) and concentration ratios of 1:1, 2:1 and 3:1 of PEg/MMT were employed. The materials were characterized using X-ray diffraction, scanning electron microscopy (SEM) and thermogravimetry. The SEM images show that the presence of PEg gives place to a large degree of exfoliation at all clay concentrations. For 5 wt% MMT, the best degree of exfoliation is obtained for a 2:1 ratio of PEg/MMT. This ratio also gives place to the largest increase of the elastic modulus, mainly at low frequencies, with respect to that of the corresponding matrix. As the clay concentration increases, for a 2:1 ratio of PEg/MMT, the dynamic moduli increases showing pseudo solid-like behavior at clay concentrations higher than 8 wt%. Moreover, the nanocomposites show rheological properties that are affected by annealing at 200°C signaling further exfoliation or improved platelet and tactoid distributions. The oxygen permeability of PE gradually decreases with clay concentration, reaching a maximum reduction of ~30% for 15 wt% MMT.