Morphology of supported polymer electrolyte ultra-thin films: a numerical study

Morphology of polymer electrolytes membranes (PEM), e.g., Nafion, inside PEM fuel cell catalyst layers has significant impact on the electrochemical activity and transport phenomena that determine cell performance. In those regions, Nafion can be found as an ultra-thin film, coating the catalyst and the catalyst support surfaces. The impact of the hydrophilic/hydrophobic character of these surfaces on the structural formation of the films has not been sufficiently explored yet. Here, we report about Molecular Dynamics simulation investigation of the substrate effects on the ionomer ultra-thin film morphology at different hydration levels. We use a mean-field-like model we introduced in previous publications for the interaction of the hydrated Nafion ionomer with a substrate, characterized by a tunable degree of hydrophilicity. We show that the affinity of the substrate with water plays a crucial role in the molecular rearrangement of the ionomer film, resulting in completely different morphologies. Detailed structural description in different regions of the film shows evidences of strongly heterogeneous behavior. A qualitative discussion of the implications of our observations on the PEMFC catalyst layer performance is finally proposed

The changing form of Antarctic biodiversity

Antarctic biodiversity is much more extensive, ecologically diverse and biogeographically structured than previously thought. Understanding of how this diversity is distributed in marine and terrestrial systems, the mechanisms underlying its spatial variation, and the significance of the microbiota is growing rapidly. Broadly recognizable drivers of diversity variation include energy availability and historical refugia. The impacts of local human activities and global environmental change nonetheless pose challenges to the current and future understanding of Antarctic biodiversity. Life in the Antarctic and the Southern Ocean is surprisingly rich, and as much at risk from environmental change as it is elsewher

Paracoccidioidomicose enzoótica em tatus (Dasypus novemcinctus) no estado do Pará

Paracoccidioides brasiliensis foi encontrado, por inoculação de triturado de fígado e baço em hamsters, em 4 de 20 tatus (Dasypus novemcinctus) examinados na região de Tucuruí, Pará. Hamsters inoculados por via intradérmica e peritoneal com o parasito desenvolveram infecções generalizadas e morreram em 1½ a 13 meses. A diagnose do fungo foi confirmada por histopatologia e cultura. Não se observaram sinais macroscópios de doenças nos tatus. A distribuição geográfica de D. novemcinctus abrange a área endêmica de paracoccidioidomicose humana, sugerindo-se que o tatu tenha algum papel na ecologia do fungo

Características del consumo de sustancias recreativas en establecimientos nocturnos del Valle de Aburrá

Objetivo: Identificar las características demográficas y de consumo de sustancias recreativas de las personas que acuden a establecimientos nocturnos de algunos municipios del Valle de Aburra.  Metodología: Estudio cross-sectional, la población estuvo compuesta por personas de ambos sexos y mayores de edad que frecuentan establecimientos nocturnos en el Valle de Aburra. Se aplicó el cuestionario SONAR 98 modificado y adaptado por los investigadores. Resultados: Se realizó en 17 centros nocturnos, participaron 789 personas, mujeres 57,7%, edad promedio 23 años, estudiantes 61,0%. La mayoría de los  encuestados habían consumido alguna vez en su vida alcohol 95%, cigarrillo 46,0%, cannabis 25,0%, nitrito de amilo “Popper” 10,0%, “drogas de diseño” como anfetaminas y metanfetaminas 9,0% y sedantes e hipnóticos 10,0%. El primer consumo, se inició de manera temprana con las llamadas drogas sociales: alcohol 14 años, y tabaco 15 años. Discusión: A diferencia de los resultados obtenidos a nivel mundial, este estudio mostró que el consumo de drogas recreativas se inicia con sustancias socialmente aceptadas, como el alcohol y el tabaco, mientras que las drogas de diseño y otras tienen un uso más restringido, y su consumo se ve relegado a edades más tardías

Effect of previous slurry ice treatment on the quality of cooked sardine (Sardina pilchardus)

6 páginas, 2 figuras, 2 tablas.-- The final publication is available at www.springerlink.comThe use of slurry ice was evaluated as a technological treatment prior to cooking processing of fish. Thus, sardine (Sardina pilchardus) was stored in slurry ice for 2, 5 and 8 days. At such times, sardine specimens were taken and subjected to steam cooking, and the results were compared with those from a parallel control batch previously stored in flake ice. Quality assessment of lipid damage in cooked fish was performed by measuring the formation of free fatty acids, peroxides, thiobarbituric acid-reactive substances and interaction compounds. The volatile amines–total and trimethylamine– assessment was also carried out. A significant (p<0.05) inhibition of lipid damage–peroxides and fluorescent compounds assessment–and trimethylamine formation was observed in cooked sardine as a consequence of the preliminary treatment in slurry ice. This work opens the way to the use of slurry ice as a preliminary treatment of fish material prior to its thermal processing.This work was supported by a project granted by the Secretar´ıa Xeral de I+D from the Xunta de Galicia (Spain) (Project PGIDIT 02 RMA 18E).Peer reviewe