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Síntese e processamento mecânico de nanocompósitos à base de magnésio para armazenagem de hidrogênio
(Universidade Federal de São Carlos, 2009-03-31) Leiva, Daniel Rodrigo; Botta Filho, Walter José; https://lattes.cnpq.br/8956458007749112
Les alliages nanocrystallines et les nanocomposites à base de magnesium sont des matériaux prometteurs pour le stockage d hydrogène dans l état solide, pour offrir une plus grande sécurité et efficaté de stockage que le H2 aux états gazeux ou liquide. Dans ce travail, la synthèse et l élaboration de ces matériaux par les techniques de broyage à haute énergie (HEBM High-energy Ball milling) et de déformation plastique sévère (SPD Severe Plastic Deformation) ont été étudiés. Nanocomposites à base de MgH2 et de Mg2FeH6 ont été préparés par broyage réactif sous atmosphère d hydrogène (une technique de HEBM) sous plusieurs conditions, pour obtenir une meilleure compréhension des effets des différents paramètres d élaboration sur la synthèse des hydrures. De plus, l utilisation des techniques de SPD de torsion sous haute pression (HPT High-pressure Torsion) et extrusion en canal angulaire (ECAP Equal Channel Angular Pressing) ont été explorés pour composer des routes d élaboration de mélanges réactifs à base de Mg pour le stockage de H2. Les matériaux preparés par les différentes méthodes ont été caracterisés par des techniques d analyse structurale comme, parmi d autres, difraction de rayons-X, microscopie optique, microscopie electronique en transmission et à balayage. Le comportement pendant la désorption a été étudié par calorimetrie différentielle de balayage, et des échantillons séléctionnés on été soumis à cycles d absorption et désorption de H2 pour mesures cinétiques. La corrélation des résultats pour les plusieurs systèmes à base de Mg a permis l obténtion d un meilleur contrôle de la synthèse des nanocomposites et une meilleure connaissance du potentiel d utilisation des techniques de SPD pour composer des routes d élaboration en envisageant les applications pour le stockage d hydrogène.
Divulgação científica em Museus de Ciências: diálogos possíveis entre as concepções dos responsáveis e a montagem das exposições
(Universidade Federal de São Carlos, 2009-03-31) Prudêncio, Christiana Andrea Vianna; Freitas, Denise de; https://lattes.cnpq.br/7915790476046108
The current work searched and analysed the conceptions that directors and coordinators responsible for the Scientific and Cultural Divulgence Center (CDCC) of São Carlos/SP (CDCC/USP) and also responsible for the Sciences Center of Araraquara/SP (CCA) have about science, the importance of scientific divulgence and the adoption of a conceptual or cultural approach of science in the interactive exibitions. The aim of this analysis was to investigate the existence of relations between these two conceptions and the organization of these exhibitions spatial distribution, the choice of the experiments and environment. The methodology used was the Discursive Textual Analysis, because it allows more comprehensive data interpretation by the researcher, who, in this process, impresses her own subjectivity in them. The research revealed that, among the responsible personnel, there is a conception of science as the language which explains nature, then its importance for the understanding of the world. The research also showed that the Brazilian Science museums are much more organized and adapted to attend school students and despite the fact that the responsible personnel recognize the importance of scientific divulgence for the citizenship experience and for a more critical positioning when facing technological-scientific subjects and the fact that the exhibitions are organized in subjects and the activities are focused mainly on the school students, still makes scientific divulgence happen within a much more conceptual approach and not in the understanding that sciences are also influenced by nonscientific factors, such as the social, political, economic and cultural ones. However, the museums which were studied have developed strategies which represent movements to warrant the lay population tools for the fight against exclusion from the scientific knowledge. Research also highlighted the need of dialog among different areas of knowledge the scientific and the traditional ones inside these institutions, and if your commitment is to help in the holistic formation of the human being and also to recognize that there are other kinds of nonscientific knowledge, but these ones are no less important, and that for a long time they have been helping the lay population to understand the world.