A family of oxide ion conductors based on the ferroelectric perovskite Na0.5Bi0.5TiO3

Oxide ion conductors find important technical applications in electrochemical devices such as solid-oxide fuel cells (SOFCs), oxygen separation membranes and sensors1, 2, 3, 4, 5, 6, 7, 8, 9. Na0.5Bi0.5TiO3 (NBT) is a well-known lead-free piezoelectric material; however, it is often reported to possess high leakage conductivity that is problematic for its piezo- and ferroelectric applications10, 11, 12, 13, 14, 15. Here we report this high leakage to be oxide ion conduction due to Bi-deficiency and oxygen vacancies induced during materials processing. Mg-doping on the Ti-site increases the ionic conductivity to ~0.01 S cm−1 at 600 °C, improves the electrolyte stability in reducing atmospheres and lowers the sintering temperature. This study not only demonstrates how to adjust the nominal NBT composition for dielectric-based applications, but also, more importantly, gives NBT-based materials an unexpected role as a completely new family of oxide ion conductors with potential applications in intermediate-temperature SOFCs and opens up a new direction to design oxide ion conductors in perovskite oxides

High throughput screening of hydrolytic enzymes from termites using a natural substrate derived from sugarcane bagasse

<p>Abstract</p> <p>Background</p> <p>The description of new hydrolytic enzymes is an important step in the development of techniques which use lignocellulosic materials as a starting point for fuel production. Sugarcane bagasse, which is subjected to pre-treatment, hydrolysis and fermentation for the production of ethanol in several test refineries, is the most promising source of raw material for the production of second generation renewable fuels in Brazil. One problem when screening hydrolytic activities is that the activity against commercial substrates, such as carboxymethylcellulose, does not always correspond to the activity against the natural lignocellulosic material. Besides that, the macroscopic characteristics of the raw material, such as insolubility and heterogeneity, hinder its use for high throughput screenings.</p> <p>Results</p> <p>In this paper, we present the preparation of a colloidal suspension of particles obtained from sugarcane bagasse, with minimal chemical change in the lignocellulosic material, and demonstrate its use for high throughput assays of hydrolases using Brazilian termites as the screened organisms.</p> <p>Conclusions</p> <p>Important differences between the use of the natural substrate and commercial cellulase substrates, such as carboxymethylcellulose or crystalline cellulose, were observed. This suggests that wood feeding termites, in contrast to litter feeding termites, might not be the best source for enzymes that degrade sugarcane biomass.</p

Saúde mental e atenção básica em saúde: análise de uma experiência no nível local Mental health and primary care: analysis of a local experience

Este artigo apresenta os resultados de uma pesquisa que teve como principal objetivo mapear as modalidades de atenção em saúde mental desenvolvidas numa unidade de saúde mista, do município do Rio de Janeiro. Partiu-se do pressuposto que os espaços de produção do cuidado à saúde mental na atenção primária podem contribuir para o processo de inversão do modelo de atenção em saúde mental, em curso no Brasil. Procura-se conhecer os modos de cuidado oferecidos pelos profissionais da unidade às necessidades de saúde identificadas como problemas de saúde mental, elencando para tal alguns eixos de análise: a noção de vínculo/acolhimento, de escuta do sujeito e de integralidade. Esta análise pautou-se na observação participante, na condução de entrevistas semi-estruturadas com profissionais da unidade de saúde e da equipe de Saúde da Família e na coleta de informações dos prontuários, através de um instrumento desenvolvido para tal finalidade. Os resultados deste estudo apontaram que, nas ações de saúde mental na atenção primária, ainda predomina o modelo biomédico de organização da atenção à saúde, a psiquiatrização do cuidado em saúde mental, a burocratização do processo de trabalho e o centramento nas ações intramuros.<br>This article presents the results of a research aimed at mapping the mental care services provided in a Primary Care Unit in the city of Rio de Janeiro. The study is based on the premise that today Primary Care can contribute to a change in the mental care model in Brazil. The practices used by the professionals of the units for dealing with problems classified as mental problems are analyzed from the perspective of concepts such as patient-centered care, listening and integrality. The study is based on participant observation, semi-structured interviews with professionals working in a Health Unit and in a Family Health Program besides information collected from medical records using a tool especially conceived for this purpose. The results of this study show that in the mental care actions offered in primary care, the biomedical model, psychiatrization of mental care and bureaucratization of the work process restricting the actions to the Unit are still prevailing