Fast oxide-ion and proton conductors are the subject of considerable research due to their technological applications in sensors, ceramic membranes and solid oxide fuel cells (SOFCs). This thesis describes the use of computer modelling techniques to study point defects, dopants and clustering effects in fluorite-and perovskitetype ion conductors with potential SOFC applications. Bi2O3 related phases are being developed with the objective of high oxide-ion conductivities at lower operating temperatures than 1000°C, as in current generation SOFC electrolytes. Doped Bi2O3 phases have shown promise as materials capable of accomplishing this goal. First, the Y-doped phase, Bi3YO6, has been investigated including the ordering of intrinsic vacancies. The defect and dopant characteristics of Bi3YO6 have been examined and show that a highly mobile oxygen sub-lattice exists in this material. A preliminary structural modelling study of a new Re-doped Bi2O3 phase was also undertaken. A comprehensive investigation of the proton-conducting perovskites BaZrO3, BaPrO3 and BaThO3 is then presented. Our results suggest that intrinsic atomic disorder in BaZrO3 and BaThO3 is unlikely, but reduction of Pr4+ in BaPrO3 is favourable. The water incorporation energy is found to be less exothermic for BaZrO3 than for BaPrO3 and BaThO3, but in all cases the results suggest that the proton concentration would decrease with increasing temperature, in accord with experimental data. The high binding energies for all the dopant-OH pair clusters in BaPrO3 and BaThO3 suggest strong proton trapping effects. Finally, a study of multiferroic BiFeO3 is presented, in which the defect, dopant and migration properties of this highly topical phase are investigated. The reduction process involving the formation of oxygen vacancies and Fe2+ is the most favourable redox process. In addition, the results suggest that oxide-ion migration is anisotropic within this system.

"Electrohydrodynamic (EHD) pumping relies on the interaction between electrical and flow fields in a dielectric fluid medium. Advantages such as simple and robust design as well as negligible vibration and noise during operation make EHD conduction pumping suitable for various applications. This work investigates meso-scale EHD conduction pumping used as an active flow distribution control mechanism for thermal management systems. Two different scenarios are considered for this purpose: alteration of uniform flow distribution and flow maldistribution correction. Its capability of actively controlling the flow distribution is examined in terms of the value of applied potential for initiation of flow divergence or flow equalization and the flow rate difference between each branch. Experimental results confirm that the reverse pumping direction configuration of EHD pumping is more effective than the same pumping direction configuration. A fundamental explanation of the heterocharge layer development is provided for the effect of flow direction on EHD conduction pumping performance. This study also involves a macro-scale EHD conduction pump used as an alternative mechanism of mixing liquid within a storage tank, for example under low-g condition. A numerical analysis of a simplified model of the experimental setup is provided to illustrate the liquid mixing and thermal homogenization process. The experimental and numerical study provide fundamental understanding of liquid mixing and thermal homogenization via EHD conduction pumping. Liquid-vapor phase change phenomena are used as effective mechanisms for heat transfer enhancement and have many applications such as HVAC&R systems. With this in mind, two detailed studies in pool boiling and in-tube flow condensation are carried out. Specifically, nucleate pool boiling on nano-textured surfaces, made of alumina ceramic substrate covered by electrospun nanofiber, is experimentally investigated. Also, the role of surface roughness and orientation in pool boiling is experimentally characterized. The in-tube convective condensation of pure water in mini-channels under sub-atmospheric pressure is also experimentally explored. This study provides valuable information for the design of condensers in a vapor compression cycle of HVAC&R systems using water as the refrigerant, this process has zero global warming potential. "

The Cone Calorimeter has been used widely for various purposes as a bench - scale apparatus. Originally the retainer frame (edge frame) was designed to reduce unrepresentative edge burning of specimens. In general, the frame has been used in most Cone tests without enough understanding of its effect. It is very important to have one - dimensional (1D) conditions in order to estimate thermal properties of materials. It has been implicitly assumed that the heat conduction in the Cone Calorimeter is 1D using the current specimen preparation. However, the assumption has not been corroborated explicitly to date. The first objective of this study was to evaluate the heat transfer behavior of a Cone specimen by examining its three - dimensional (3D) heat conduction. It is essential to understand the role of wall lining materials when they are exposed to a fire from an ignition source. Full - scale test methods permit an assessment of the performance of a wall lining material. Fire growth models have been developed due to the costly expense associated with full - scale testing. The models require heat flux maps from the ignition burner flame as input data. Work to date was impeded by a lack of detailed spatial characterization of the heat flux maps due to the use of limited instrumentation. To increase the power of fire modeling, accurate and detailed heat flux maps from the ignition burner are essential. High level spatial resolution for surface temperature can be provided from an infrared camera. The second objective of this study was to develop a heat flux mapping procedure for a room test burner flame to a wall configuration with surface temperature information taken from an infrared camera. A prototype experiment is performed using the ISO 9705 test burner to demonstrate the developed heat flux mapping procedure. The results of the experiment allow the heat flux and spatial resolutions of the method to be determined and compared to the methods currently available.

Digitized by Kansas Correctional Industries

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1979. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / by James R. Rinderle. / M.S.

A neuropatia motora multifocal (NMM) é uma neuropatia inflamatória de baixa prevalência, 0,6/100.000 pacientes, caracterizada por uma fraqueza muscular progressiva, assimétrica e distal, sem comprometimento sensitivo. A NMM pode mimetizar a esclerose lateral amiotrófica (ELA), outras variantes da doença do neurônio motor e outras polineuropatias inflamatórias desmielinizantes crônicas, com início assimétrico. A diferenciação é importante, tendo em vista as especificidades da evolução e do tratamento das referidas neuropatias. O principal achado eletrofisiológico é o bloqueio de condução nervosa na ausência de anormalidades sensitivas. A fisiopatogenia da NMM é pouco conhecida. O frequente achado de anticorpos circulantes contra o monoassialogangliosídeo (GM1) é sugestivo de que possa haver seu comprometimento em alterações estruturais nodais e perinodais, com comprometimento multifocal da condução nervosa. O corolário desses distúrbios são paresias e paralisias, também de distribuição multifocal. A Imunoglobulina humana por via endovenosa em altas doses constitui o tratamento de escolha. Novas estratégias de tratamento alternativas são necessárias para prevenir fraqueza muscular permanente e incapacidade. Poucos estudos e revisões bibliográficas têm elucidado as características clínicas da NMM, com a ausência na literatura de publicações de série de casos nacionais. No presente estudo, a partir de uma revisão retrospectiva, serão avaliados os aspectos clínicos- eletrofisiológicos da NMM, a fim de se obter um maior entendimento da evolução da doença. / The multifocal motor neuropathy (MMN) is an inflammatory neuropathy that has low prevalence (0.6 / 100,000 patients). It is characterized by progressive, asymmetric and distal muscle weakness without sensory impairment. The MMN can mimic amyotrophic lateral sclerosis (ALS), other motor neuron disease variants and other chronic inflammatory demyelinating polyneuropathy, with asymmetric start. Differentiation is important, given the specificities of the development and treatment of these neuropathies. The main electrophysiological finding is the nerve conduction block in the absence of sensory abnormalities. The pathophysiology of MMN is little known. The frequent finding of circulating antibodies against monoassialogangliosides (GM1) is suggestive that there may be their involvement in nodal and perinodal structural changes with multifocal impairment of nerve conduction. The corollary of these disorders is paresis and paralysis, with also multifocal distribution. The human immunoglobulin intravenously in high doses constitutes the treatment of choice. New alternative treatment strategies are needed to prevent permanent muscle weakness and disability. Few studies and literature reviews have elucidated the clinical features of MMN and there are no case series publications in the national literature. In this study, from a retrospective review, will be assessed clinic and electrophysiological features of MMN in order to obtain a greater understanding of disease progression.

Xie Jian Li. / "August 2003." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (p. 106-109). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

O presente trabalho utiliza o método Design Construtal para desenvolver o estudo numérico de uma configuração de caminhos de alta condutividade de geometria trifurcada que minimiza a resistência ao fluxo de calor, quando a área do caminho trifurcado é mantida constante. O objetivo deste trabalho é o estudo da influência da geometria sobre o desempenho térmico do sistema bem como a otimização do mesmo, assim obtendo uma configuração que minimiza a resistência térmica para cada condição imposta. São apresentadas as considerações e hipóteses utilizadas para a análise, obtendo a equação do calor regente e as condições de contorno do problema, bem como a função objetivo. Para a solução numérica da equação da condução do calor, é utilizado o software MATLAB ®, especificamente as ferramentas PDETOOL, Partial Differential Equations Tool, e GA, Algoritmo Genético. A resistência térmica é minimizada para cada grau de liberdade. A cada nível de otimização, a influência do grau de liberdade em questão é estudada, obtendo um mapeamento da importância de cada grau de liberdade sobre o sistema trifurcado. Também são obtidas as configurações ótimas para diferentes frações de área. Posteriormente, é estudado o comportamento da configuração ótima do sistema para diferentes temperaturas do final das bifurcações do sistema, mostrando que, para as temperaturas estudadas neste trabalho, a configuração ótima não se altera, apenas a resistência térmica, com a alteração na temperatura do sumidouro direito sendo mais influente sobre essa, seguida do sumidouro central e, por fim, do sumidouro esquerdo. Finalmente, este trabalho mostra, com esses resultados, que a geometria ótima é aquela que melhor distribui as imperfeições do sistema, de acordo com o princípio da ótima distribuição das imperfeições e, também, possui robustez quanto às pequenas imperfeições inseridas no sistema. / The present work employs Constructal Design method to develop a numerical study of a triforked high conductivity pathway that minimizes the heat flow resistance when the triforked pathway area is kept constant. The objective of this work is the study of the influence of the geometry over the thermal performance of the system as well as the optimization of the latter, thus obtaining a configuration that minimizes the thermal resistance for each imposed condition. The considerations and hypothesis for the analysis are shown, obtaining a reigning heat equation and boundary conditions for the system, as well as the objetctive function (minimization of the maximum temperature). For the numerical solution of the heat conduction equation, it is utilized MATLAB ® software, specifically the PDETOOL, Partial Differential Equations Tool, and GA, Genetic Algorithm, toolboxes. The thermal resistance is minimized for every degree of freedom. In each level of optimization, the influence of the degree of freedom in question is studied, obtaining a mapping of the importance of each degree of freedom over the performance of the triforked pathway. Optimal configurations are also obtained for different area fractions. Posteriorly, the behavior of the optimal geometry is studied for different temperatures of the branches of the system. Results show that, for the temperatures studied in this work, the optimal configuration does not change, only the thermal resistance, with the increase of temperature of the right sink being more influential over it, followed by the temperature of the middle sink and, at last, the temperature of the left sink. Finally, this work shows, with these results, that the optimal geometry is the one that better distributes the imperfections of the systems, which is in accordance to the principle of the optimal distribution of imperfections, while possessing a certain robustness over small imperfections inserted in the system.

As células a combustível a etanol direto (DEFCs) são consideradas geradores de energia eficientes e de baixo impacto ambiental. O foco deste trabalho é avançar o entendimento sobre eletrólitos compósitos híbridos do tipo Nafion-cerâmica visando o aumento do desempenho das DEFCs operando em T ~ 130 °C. Partículas inorgânicas foram crescidas na matriz polimérica formando os compósitos Nafion-Sílica (NS), Nafion-Fosfato de Zircônio (NZ) e Nafion-Titânia (NT). Este último (NT) serviu como material precursor para a conversão in situ da titânia em nanotubos de titanato de hidrogênio por uma rota hidrotérmica alcalina assistida por micro-ondas (NNTH). A relação microestrutura-propriedades elétricas foi estudada por meio de medidas de espectroscopia dielétrica, análise dinâmico-mecânica, calorimetria diferencial exploratória e espalhamento de raios X em baixo ângulo. Estas técnicas contribuíram, por exemplo, para inferir a localização das partículas inorgânicas na estrutura multifásica do Nafion e estabelecer a sua influência nas propriedades gerais dos compósitos. Os resultados indicaram que as interações de repulsão eletrostática de longo alcance entre os grupos sulfônicos do Nafion hidratado provocam a transição conformacional das cadeias principais do estado enovelado para a conformação tipo bastão. Tal transição promove a redução da condutividade protônica e da estabilidade mecânica do Nafion para temperaturas acima da temperatura da relaxação (Tα ~ 110 °C), a qual pode ser deslocada para maiores temperaturas (T > 160 °C) nos compósitos híbridos. A interação das partículas de sílica e de titânia com a fase condutora do Nafion é maximizada, enquanto que as partículas de fosfato de zircônio estão localizadas majoritariamente nos domínios apolares. As interações entre os grupos sulfônicos do Nafion e as partículas de titânia contribuíram para a melhora das propriedades mecânicas em altas temperaturas e para a redução da permeabilidade ao etanol, as quais promoveram o aumento do desempenho da DEFC em altas temperaturas. A baixa permeabilidade ao etanol e as melhores propriedades termomecânicas e de transporte protônico dos compósitos NNTH refletiram em um elevado desempenho das DEFCs a 130 °C, evidenciando que estes eletrólitos compósitos são promissores para a aplicação pretendida. / Direct Ethanol Fuel Cells (DEFCs) are considered a clean and high efficient power source. The focus of this thesis is to contribute to advance the understanding of Nafion-based hybrid composites aiming at high-performance DEFCs operating at elevated temperatures (T ~ 130 °C). Three inorganic particles were grown in the polymer matrix forming the electrolyte composites Nafion-Silica (NS), Nafion-Zirconium Phosphate (NZ), and Nafion-Titania (NT). The latter (NT) served as a precursor composite for the in situ conversion of titania into hydrogen titanate nanotubes by a microwave-assisted alkaline hydrothermal reaction (NNTH). The relation microstructure-eletrical property was studied by dielectric spectroscopy, dynamic-mechanical analysis, differential scanning calorimetry, and small angle X-ray scattering. Such techniques contributed, for example, to infer the localization of the inorganic particles in the Nafion multiphase structure and to establish its influence in the general properties of the composites. The results indicated that long range electrostatic repulsion occurring within Nafion ionic groups promotes a conformational transition of the polymer main chains from entangled to rodlike. Such transition reduces both the proton conductivity and the mechanical stability at temperatures higher than relaxation temperature (Tα ~ 110 °C), which was found to be shifted to higher T > 160 ºC in the hybrid composites. The interaction between silica and titania particles with Nafion conducting phase is maximized, while the zirconium phosphate particles occupy preferably the hydrophobic domains. The interactions between Nafion sulfonic acid groups and titania particles contributed to the improvement of the mechanical properties at high temperature and to the lowering of ethanol permeability that increased DEFC performance at high temperature. The low ethanol permeability, high mechanical and electrical properties of NNTH reflected in the high DEFC performance at 130 °C, evidencing this composite as a promising electrolyte for the intended application.

O envolvimento do sistema nervoso periférico em diversas doenças auto-imunes é bem estabelecido. No entanto, não existem estudos, com desenho metodológico apropriado, que tenham investigado a relação entre síndrome antifosfolípide primária (SAFP) e neuropatia periférica. Nosso objetivo nesse trabalho foi investigar a ocorrência de neuropatia periférica em pacientes com SAFP. Vinte e seis pacientes com SAFP (critérios de Sapporo) e vinte controles, saudáveis, pareados por sexo e idade, foram recrutados em dois centros de referência. Foram excluídas as causas secundárias de neuropatia periférica e um exame neurológico completo, seguido de estudo de neurocondução, foi realizado em todos os indivíduos. Parestesias foram observadas em oito pacientes (31%). Leve fraqueza distal e anormalidades nos reflexos tendíneos profundos, foram observados em três (11,5%) pacientes. Evidência eletrofisiológica de neuropatia periférica foi observada em nove (35%) pacientes: quatro (15,5%) pacientes apresentaram neuropatia sensitiva ou sensitivo-motora axonal distais (em dois deles, com a superposição de síndrome do túnel do carpo), um (4%) paciente apresentou neuropatia sensitivo-motora, axonal e desmielinizante, acometendo os membros superiores e inferiores, enquanto que em quatro (15,5%) pacientes, observou-se a presença isolada de síndrome do túnel do carpo. As alterações clínicas e sorológicas dos pacientes com SAFP não guardaram qualquer correlação, com as alterações eletrofisiológicas. Em conclusão, neuropatia periférica, em geral assintomática, é comum na SAFP. Estudo de condução nervosa deve ser considerado na avaliação desses pacientes. / The involvement of the peripheral nervous system in diverse autoimmune diseases is well established. However, no appropriately designed studies have been performed in primary antiphospholipid syndrome (PAPS)-related peripheral neuropathy. We aimed to investigate the occurrence of peripheral neuropathy in patients diagnosed with PAPS. Twenty-six consecutive PAPS (Sapporo\'s criteria) patients and twenty age- and gender-matched healthy controls were enrolled at two referral centers. Exclusion criteria were secondary causes of peripheral neuropathy. A complete clinical neurological exam followed by nerve conduction studies (NCSs) were performed. Paresthesias were reported in 8 patients (31%). Objective mild distal weakness and abnormal symmetric deep tendon reflexes were observed in three (11.5%) patients. With regard to the electrophysiological evidence of peripheral neuropathy, nine (35.0%) patients had alterations: four (15.5%) had pure sensory or sensorimotor distal axonal neuropathy (in two of them a carpal tunnel syndrome was also present) and one (4%) had sensorimotor demyelinating and axonal neuropathy involving upper and lower extremities, while four patients (15.5%) showed isolated carpal tunnel syndrome. Clinical and serological results were similar in all PAPS patients, regardless of the presence of electrophysiological alterations. In conclusion, peripheral neuropathy is a common asymptomatic abnormality in PAPS patients. The routine performance of NCS may be considered when evaluating such patients.