8 resultados para Zatulovskaja, Irina
Resumo:
Nucleic Acid Research (2007) Vol.37 N. 14 4755-4766
Resumo:
Journal of Bacteriology (Apr 2006) 3024-3036
Resumo:
Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para a obtenção do grau de Mestre em Engenharia do Ambiente,Perfil Gestão de Sistemas Ambientais
Resumo:
Dissertação Apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em Ciências da Conservação, especialização em Pintura
Resumo:
Dissertação para obtenção do Grau de Mestre em Engenharia do Ambiente, perfil Engenharia Sanitária
Resumo:
Dissertação para obtenção do Grau de Mestre em Tecnologia e Segurança Alimentar
Resumo:
Este trabalho tem como objetivo central dar conta das atividades realizadas no âmbito da prática de ensino supervisionada em Português Língua Materna e Espanhol Língua Estrangeira. A prática pedagógica alicerçou-se na indissociabilidade entre a literatura e a gramática. Defende-se que o texto literário deve ser entendido como uma várias manifestações da língua, criada num contexto comunicativo particular em que são empregues determinadas estruturas linguísticas, mediante os objetivos comunicativos de quem o produz. Esta orientação pragmática e funcional do ensino-aprendizagem das línguas faz do aluno um agente atuante no processo de comunicação e, por isso, é da maior importância que apreenda e consolide os mecanismos linguísticos que façam dele um falante eficaz e socialmente integrado
Resumo:
With the projection of an increasing world population, hand-in-hand with a journey towards a bigger number of developed countries, further demand on basic chemical building blocks, as ethylene and propylene, has to be properly addressed in the next decades. The methanol-to-olefins (MTO) is an interesting reaction to produce those alkenes using coal, gas or alternative sources, like biomass, through syngas as a source for the production of methanol. This technology has been widely applied since 1985 and most of the processes are making use of zeolites as catalysts, particularly ZSM-5. Although its selectivity is not especially biased over light olefins, it resists to a quick deactivation by coke deposition, making it quite attractive when it comes to industrial environments; nevertheless, this is a highly exothermic reaction, which is hard to control and to anticipate problems, such as temperature runaways or hot-spots, inside the catalytic bed. The main focus of this project is to study those temperature effects, by addressing both experimental, where the catalytic performance and the temperature profiles are studied, and modelling fronts, which consists in a five step strategy to predict the weight fractions and activity. The mind-set of catalytic testing is present in all the developed assays. It was verified that the selectivity towards light olefins increases with temperature, although this also leads to a much faster catalyst deactivation. To oppose this effect, experiments were carried using a diluted bed, having been able to increase the catalyst lifetime between 32% and 47%. Additionally, experiments with three thermocouples placed inside the catalytic bed were performed, analysing the deactivation wave and the peaks of temperature throughout the bed. Regeneration was done between consecutive runs and it was concluded that this action can be a powerful means to increase the catalyst lifetime, maintaining a constant selectivity towards light olefins, by losing acid strength in a steam stabilised zeolitic structure. On the other hand, developments on the other approach lead to the construction of a raw basic model, able to predict weight fractions, that should be tuned to be a tool for deactivation and temperature profiles prediction.