A simulation study on the abatement of CO2 emissions by de-absorption with monoethanolamine

Because of the adverse effect of CO2 from fossil fuel combustion on the earth's ecosystems, the most cost-effective method for CO2 capture is an important area of research. The predominant process for CO2 capture currently employed by industry is chemical absorption in amine solutions. A dynamic model for the de-absorption process was developed with monoethanolamine (MEA) solution. Henry's law was used for modelling the vapour phase equilibrium of the CO2, and fugacity ratios calculated by the Peng-Robinson equation of state (EOS) were used for H2O, MEA, N-2 and O-2. Chemical reactions between CO2 and MEA were included in the model along with the enhancement factor for chemical absorption. Liquid and vapour energy balances were developed to calculate the liquid and vapour temperature, respectively.

Malaria transmission model for different levels of acquired immunity and temperature-dependent parameters (vector)

OBJECTIVE: Describe the overall transmission of malaria through a compartmental model, considering the human host and mosquito vector. METHODS: A mathematical model was developed based on the following parameters: human host immunity, assuming the existence of acquired immunity and immunological memory, which boosts the protective response upon reinfection; mosquito vector, taking into account that the average period of development from egg to adult mosquito and the extrinsic incubation period of parasites (transformation of infected but non-infectious mosquitoes into infectious mosquitoes) are dependent on the ambient temperature. RESULTS: The steady state equilibrium values obtained with the model allowed the calculation of the basic reproduction ratio in terms of the model's parameters. CONCLUSIONS: The model allowed the calculation of the basic reproduction ratio, one of the most important epidemiological variables.

Avaliação da dose absorvida na tiróide, em cintigrafias com 123I e Na99mTcO4 utilizando modelos biocinéticos e métodos de Monte Carlo

Mestrado em Radiações Aplicadas às Tecnologias da Saúde. Área de especialização: Protecção contra Radiações

A mathematical model for malaria transmission relating global warming and local socioeconomic conditions

OBJECTIVE: Sensitivity analysis was applied to a mathematical model describing malaria transmission relating global warming and local socioeconomic conditions. METHODS: A previous compartment model was proposed to describe the overall transmission of malaria. This model was built up on several parameters and the prevalence of malaria in a community was characterized by the values assigned to them. To assess the control efforts, the model parameters can vary on broad intervals. RESULTS: By performing the sensitivity analysis on equilibrium points, which represent the level of malaria infection in a community, the different possible scenarios are obtained when the parameters are changed. CONCLUSIONS: Depending on malaria risk, the efforts to control its transmission can be guided by a subset of parameters used in the mathematical model.

Contact angle of a hemispherical bubble: An analytical approach

We have calculated the equilibrium shape of the axially symmetric Plateau border along which a spherical bubble contacts a flat wall, by analytically integrating Laplace's equation in the presence of gravity, in the limit of small Plateau border sizes. This method has the advantage that it provides closed-form expressions for the positions and orientations of the Plateau border surfaces. Results are in very good overall agreement with those obtained from a numerical solution procedure, and are consistent with experimental data. In particular we find that the effect of gravity on Plateau border shape is relatively small for typical bubble sizes, leading to a widening of the Plateau border for sessile bubbles and to a narrowing for pendant bubbles. The contact angle of the bubble is found to depend even more weakly on gravity. (C) 2009 Elsevier Inc. All rights reserved.

Cyclic deformation of bidisperse two-dimensional foams

In-plane deformation of foams was studied experimentally by subjecting bidisperse foams to cycles of traction and compression at a prescribed rate. Each foam contained bubbles of two sizes with given area ratio and one of three initial arrangements: sorted perpendicular to the axis of deformation (iso-strain), sorted parallel to the axis of deformation (iso-stress), or randomly mixed. Image analysis was used to measure the characteristics of the foams, including the number of edges separating small from large bubbles N-sl, the perimeter (surface energy), the distribution of the number of sides of the bubbles, and the topological disorder mu(2)(N). Foams that were initially mixed were found to remain mixed after the deformation. The response of sorted foams, however, depended on the initial geometry, including the area fraction of small bubbles and the total number of bubbles. For a given experiment we found that (i) the perimeter of a sorted foam varied little; (ii) each foam tended towards a mixed state, measured through the saturation of N-sl; and (iii) the topological disorder mu(2)(N) increased up to an "equilibrium" value. The results of different experiments showed that (i) the change in disorder, Delta mu(2)(N), decreased with the area fraction of small bubbles under iso-strain, but was independent of it under iso-stress; and (ii) Delta mu(2)(N) increased with Delta N-sl under iso-strain, but was again independent of it under iso-stress. We offer explanations for these effects in terms of elementary topological processes induced by the deformations that occur at the bubble scale.

Effect of the number of shells on the pressure and energy of two-dimensional free bubble clusters

We have performed Surface Evolver simulations of two-dimensional hexagonal bubble clusters consisting of a central bubble of area lambda surrounded by s shells or layers of bubbles of unit area. Clusters of up to twenty layers have been simulated, with lambda varying between 0.01 and 100. In monodisperse clusters (i.e., for lambda = 1) [M.A. Fortes, F Morgan, M. Fatima Vaz, Philos. Mag. Lett. 87 (2007) 561] both the average pressure of the entire Cluster and the pressure in the central bubble are decreasing functions of s and approach 0.9306 for very large s, which is the pressure in a bubble of an infinite monodisperse honeycomb foam. Here we address the effect of changing the central bubble area lambda. For small lambda the pressure in the central bubble and the average pressure were both found to decrease with s, as in monodisperse clusters. However, for large,, the pressure in the central bubble and the average pressure increase with s. The average pressure of large clusters was found to be independent of lambda and to approach 0.9306 asymptotically. We have also determined the cluster surface energies given by the equation of equilibrium for the total energy in terms of the area and the pressure in each bubble. When the pressures in the bubbles are not available, an approximate equation derived by Vaz et al. [M. Fatima Vaz, M.A. Fortes, F. Graner, Philos. Mag. Lett. 82 (2002) 575] was shown to provide good estimations for the cluster energy provided the bubble area distribution is narrow. This approach does not take cluster topology into account. Using this approximate equation, we find a good correlation between Surface Evolver Simulations and the estimated Values of energies and pressures. (C) 2008 Elsevier B.V. All rights reserved.

Iniciação da marcha em indivíduos com AVE. Sequência de ativação muscular do tibial anterior e solear

Introdução: A iniciação da marcha, enquanto tarefa motora complexa que consiste na transição de uma postura mantida pelo apoio simultâneo dos dois membros inferiores para um equilíbrio dinâmico, permitindo a progressão anterior do corpo, constitui um exemplo que implica uma correta sequência de ativação muscular. Objetivos: Verificar a modificação da fase de iniciação da marcha face à aplicação de um programa de recuperação funcional, analisando a sequência de ativação dos músculos tibial anterior e solear. Registar as repercussões funcionais na participação nas diferentes atividades da vida diária, em contexto padronizado e social. Metodologia: Nos dois participantes em estudo foi realizada uma avaliação antes e após um programa de intervenção, segundo a abordagem do Conceito de Bobath, através da Classificação Internacional de Funcionalidade, Incapacidade e Saúde, da Fugl Meyer Assessment of Sensorymotor Recovery After Stroke, electromiografia e plataforma de forças. Resultados: Após a aplicação do programa de recuperação funcional, verificaram-se alterações na sequência de ativação do tibial anterior e solear. O músculo tibial anterior passou a ser o primeiro a ser recrutado nesta sequência. Conclusão: Foi possível verificar modificações durante a fase de iniciação da marcha, face a um programa de recuperação funcional, em que a sequência de ativação do tibial anterior e solear, tendencialmente, se assemelharam ao comportamento em indivíduos saudáveis, repercutindo-se numa melhoria funcional na participação nas atividades da vida diária.

Associação entre polimorfismo inserção/delecção da enzima conversora da angiotensina na diabetes mellitus tipo 2: estudo da população portuguesa

A Diabetes mellitus tipo 2 (DM2) é uma patologia de etiologia múltipla à qual estão associados vários factores genéticos. A Enzima Conversora da Angiotensina (ECA) tem sido alvo de vários estudos pela sua relação com factores pró-inflamatórios, pró-oxidantes e pró-fibrose, sendo o polimorfismo de Inserção/Delecção o mais estudado. Neste contexto, o objectivo deste estudo é assim verificar a distribuição deste polimorfismo numa amostra de indivíduos de nacionalidade portuguesa e verificar a sua possível associação com a DM2. Para tal, foram analisadas 87 amostras (controlos n =24 e diabéticos n =63) de indivíduos de nacionalidade portuguesa. As amostras foram submetidas a um processo de extracção de ADN, sendo posteriormente amplificadas por Polymerase Chain Reaction e analisadas por eletroforese em gel de agarose a 1%. Observou-se uma prevalência de 8% (n=7) com genótipo I/I, 38% (n=33) com genótipo I/D e 54% (n=47) com genótipo D/D. A amostra em estudo demonstrou assim estar sob o equilíbrio Hardy-Weinberg. Observou-se também uma associação entre níveis mais elevados de glicemia e o genótipo I/I (p=0,019). Na análise da utilização de insulina no controlo dos níveis de glicemia na DM2, observou-se uma maior proporção de indivíduos com genótipo D/D. Este estudo demonstra a importância do investimento da caracterização genética em patologias metabólicas multifactoriais como a DM2.

Spontaneous leptonic CP violation and nonzero theta(13)

We consider a simple extension of the Standard Model by adding two Higgs triplets and a complex scalar singlet to its particle content. In this framework, the CP symmetry is spontaneously broken at high energies by the complex vacuum expectation value of the scalar singlet. Such a breaking leads to leptonic CP violation at low energies. The model also exhibits an A(4) X Z(4) flavor symmetry which, after being spontaneously broken at a high-energy scale, yields a tribimaximal pattern in the lepton sector. We consider small perturbations around the tribimaximal vacuum alignment condition in order to generate nonzero values of theta(13), as required by the latest neutrino oscillation data. It is shown that the value of theta(13) recently measured by the Daya Bay Reactor Neutrino Experiment can be accommodated in our framework together with large Dirac-type CP violation. We also address the viability of leptogenesis in our model through the out-of-equilibrium decays of the Higgs triplets. In particular, the CP asymmetries in the triplet decays into two leptons are computed and it is shown that the effective leptogenesis and low-energy CP-violating phases are directly linked.

Chromatographic behaviour of monoclonal antibodies against wild-type amidase from Pseudomonasaeruginosa on immobilized metal chelates

The aim of this work was to devise a one-step purification procedure for monoclonal antibodies (MAbs) of IgG class by immobilized metal affinity chromatography (IMAC). Therefore, several stationary phases were prepared containing immobilized metal chelates in order to study the chromatographic behaviour of MAbs against wild-type amidase from Pseudomonas aeruginosa. Such MAbs adsorbed to Cu(II), Ni(II), Zn(II) and Co(II)-IDA agarose columns. The increase in ligand concentration and the use of longer spacer arms and higher pH values resulted in higher adsorption of MAbs into immobilized metal chelates. The dynamic binding capacity and the maximum binding capacity were 1.33 +/- 0.015 and 3.214 +/- 0.021 mg IgG/mL of sedimented commercial matrix, respectively. A K(D) of 4.53 x 10(-7) M was obtained from batch isotherm measurements. The combination of tailor-made stationary phases of IMAC and the correct selection of adsorption conditions permitted a one-step purification procedure to be devised for MAbs of IgG class. Culture supernatants containing MAbs were purified by IMAC on commercial-Zn(II) and EPI-30-IDA-Zn(II) Sepharose 6B columns and by affinity chromatography on Protein A-Sepharose CL-4B. This MAb preparation revealed on SDS-PAGE two protein bands with M(r) of 50 and 22 kDa corresponding to the heavy and light chains, respectively. Copyright (C) 2011 John Wiley & Sons, Ltd.

Communication: The criticality of self-assembled rigid rods on triangular lattices

The criticality of self-assembled rigid rods on triangular lattices is investigated using Monte Carlo simulation. We find a continuous transition between an ordered phase, where the rods are oriented along one of the three (equivalent) lattice directions, and a disordered one. We conclude that equilibrium polydispersity of the rod lengths does not affect the critical behavior, as we found that the criticality is the same as that of monodisperse rodson the same lattice, in contrast with the results of recently published work on similar models. (C) 2011 American Institute of Physics. [doi:10.1063/1.3556665]

Reentrant Phase Diagram of Network Fluids

We introduce a microscopic model for particles with dissimilar patches which displays an unconventional "pinched'' phase diagram, similar to the one predicted by Tlusty and Safran in the context of dipolar fluids [Science 290, 1328 (2000)]. The model-based on two types of patch interactions, which account, respectively, for chaining and branching of the self-assembled networks-is studied both numerically via Monte Carlo simulations and theoretically via first-order perturbation theory. The dense phase is rich in junctions, while the less-dense phase is rich in chain ends. The model provides a reference system for a deep understanding of the competition between condensation and self-assembly into equilibrium-polymer chains.

Efeito do calçado MBT, na variação do centro de pressão, durante o equilíbrio estático

Objectivo: Analisar a variação do centro de pressão (CP) com a utilização do calçado MBT, no equilíbrio estático a curto e longo prazo. Metodologia: A amostra é constituída por dois grupos, experimental e controlo. O estudo consistiu em dois momentos de avaliação, na recolha os indivíduos estão sobre a plataforma, estáticos. Os dados recolhidos foram a área, distância e velocidade das oscilações do CP. Resultados: As variáveis estudadas estão aumentadas com o uso das MBT. A longo prazo não se verificou diferenças significativas entre os grupos. Conclusão: As sapatilhas MBT proporcionam o aumento das oscilações do CP a curto prazo.

Análise da actividade electromiográfica durante o equilíbrio estático, com calçado MBT e descalço

O objectivo deste estudo foi analisar a influência das sapatilhas MBT na actividade electromiográfica dos músculos tibial anterior (TA) e gastrocnémio medial (GM), no equilíbrio estático, a curto e longo prazo. Foi recolhido o sinal electromiográfico de 30 indivíduos em dois momentos distintos, com 8 semanas de intervalo entre eles. Cada momento consistiu em três ensaios de equilíbrio estático descalço e três com sapatilhas MBT. As variáveis em estudo aumentaram a curto prazo com o calçado MBT. A longo prazo não se verificaram diferenças significativas. Os resultados confirmam que as sapatilhas MBT aumentam a actividade muscular do GM, no equilíbrio estático.