Singular perturbations for phase transitions

nuloWe present a short overview of some singular perturbation problems that arise in the  context of phase transitions

Caracterização de membranas microporosas de titanossilicatos por permeação de um gás puro

Mestrado em Engenharia QuímicaNos últimos anos, as membranas inorgânicas microporosas têm vindo a ganhar cada vez mais interesse na comunidade científica, devido às vantagens que apresentam em relação às poliméricas. Neste âmbito, o Laboratório Associado CICECO, sediado na Universidade de Aveiro, tem desenvolvido investigação intensiva na preparação de novas membranas microporosas de titanossilicatos, particularmente de ETS-10 e AM-3. Todavia, os processos de síntese baseiam-se em métodos de tentativa e erro, ou seja, depois de preparadas, as membranas são caracterizadas para se optimizarem as condições de síntese até completa eliminação dos seus defeitos. Neste trabalho pretendeu-se caracterizar dinamicamente algumas membranas de ETS-10 e AM-3 por ensaios de permeação com azoto gasoso. Efectuaram-se testes a temperatura fixa e a temperatura programada para diferentes quedas de pressão transmembranar. Os primeiros permitiram detectar a presença de macro e mesodefeitos e confirmar as propriedades hidrofílicas dos cristais. As experiências a temperatura programada possibilitaram discriminar os mecanismos responsáveis pelo transporte de massa na membrana. Assim, constatou-se a ausência de fluxo viscoso e de difusão gasosa activada, tendose identificado as contribuições de Knudsen e de difusão superficial. A modelação da permeância do ETS-10 em função da temperatura confirmou estes resultados e forneceu um desvio absoluto médio de apenas 0.88%. ABSTRACT: Microporous inorganic membranes have been increasingly studied during last few years, due to their advantages in comparison with the polymeric ones. ETS-10 and AM-3 titanossilicate microporous membranes have been synthesised in the Associated Laboratory CICECO at University of Aveiro. The process is based on a trial and error method, i.e. once prepared, the membranes are characterized and the preparation conditions subsequently optimized until total elimination of defects. In this work the dynamic characterization of microporous ETS-10 and AM-3 membranes has been carried out by measuring pure nitrogen permeation. Fixed temperature and programmed temperature experiments were performed at several transmembrane pressure drops. The first ones allowed us to identify the presence of rough defects in the membrane and to confirm the hydrophilic properties of these crystals. The temperature programmed assays supplied information about the mass transport mechanisms involved. Accordingly, viscous and activated gaseous diffusion were absent and both adsorption and Knudsen contributions have been found. The modeling of the ETS-10 membrane permeance confirmed such findings, and gave rise to an average absolute deviation of only 0.88%

Prevalence and factors associated with diabetes mellitus among tuberculosis patients: a nationwide cohort

In Press, Corrected ProofThe association between diabetes mellitus (DM) and tuberculosis (TB) has been a matter of study worldwide, since it is assumed that DM triples the risk of TB. Recent studies have found discrepant prevalence of DM among TB patients, ranging from 5.3% in Denmark to 44% in India. There is an urgent need to control both epidemics in order to achieve the World Health Organization (WHO) TB elimination goal. To reach this goal, an integrated approach between TB elimination strategies and control of noncommunicable diseases that perpetuate the risk for TB is fundamental.(undefined

P.M.: Characterization of generalized Young measures in the A-quasiconvexity context

Abstract This work is devoted to the characterization of generalized Young measures generated by sequences of bounded Radon measures {µn} ⊂ M(Ω; such that {Aµn} converges to zero strongly in W −1,q , for some q ∈ " 1, , and A is a first order partial differential operator with constant rank