Materiais Avançados para Aplicações Especiais

Abstract

Scientifically based technological development of new materials has enabled the advent of very specific materials for special applications. One of these applications includes the direct utilization of ethanol as fuel in a solid oxide fuel cell -SOFC. SOFCs are among the most efficient electric energy generators known to date and the use of a liquid fuel, which is easy to store and transport, and is also easily available, is of great interest. However, the use of ethanol in fuel cells usually requires to be previously reformed to produce hydrogen, which, once purified, is used as fuel. The reason for that is that the direct utilization of ethanol as fuel in an SOFC induces the deposition of solid carbon, as a result of ethanol's pyrolysis at the elevated operating temperature of the fuel cell. The deposition of solid carbon on a conventional SOFC anode fills up its pores, making it difficult for the fuel gas to go through and building up internal pressure, which ends up causing the complete inactivation of the anode and, moreover, of the fuel cell itself. Figure 2. In this case, the ceramic electrocatalist was synthesized by the amorphous citrate method. The synthesis procedures were designed to produce nanometric sized powders for which the calcination conditions were selected in order to fulfill requirements such as ease to be sintered; formation of selected phases upon calcinations at different temperatures; particle size control; surface area and morphology well suited for the production of ceramic suspensions to be processed into an SOFC functional anode. The main results have shown that [4] calcination under an oxidizing atmosphere induces the CeAlO3 phase with a tetragonal perovskite type structure to undergo a phase transformation to CeO2, with cubic fluorite type structure, and Al2O3. However, the structure is able to be reversed and reduced back to the CeAlO3 phase if calcined under a hydrogen atmosphere.As a result, the controlled synthesis of the new advanced ceramic material [3,4] and its incorporation into a ceramic suspension that allows the fabrication of the functional anode was successfully used in the special application that involves the direct utilization of ethanol as fuel in an SOFC with adequate performance [1]. This was possible because the anode microstructure was not seriously affected by the direct use of ethanol, showing good stability and resistance to coking, carbon clogging and cracking.The journal Materia is receptive to publish reports on new materials developments that may open new applications for engineering devices.

Conhecimento de acadêmicos de Odontologia sobre o uso de anestésicos locais

“…Os dados foram analisados por meio de estatísticas descritivas. Para analisar a associação em relação às variáveis categóricas foi utilizado o teste do qui-quadrado de Pearson 13 , com nível de significância de 5%. O software utilizado na análise foi o Epi-Info versão 3.5.3 para Windows 14 , que é desenvolvido e distribuído gratuitamente pelo CDC (www.cdc.org/epiinfo).…”