With the growing interest in low-permeability gas plays, foam fracturing fluids are now well established as a viable alternative to traditional fracturing fluids. Present practices in energized fracturing treatments remain nonetheless rudimentary in comparison to other fracturing fluid technologies because of our limited understanding of multi-phase fluid-loss and phase behavior occurring in these complex fluids. This report assesses the fluid-loss benefits introduced by energizing the fracturing fluid. A new laboratory apparatus has been specifically designed and built for measuring the leak-off rates for both gas and liquid phases under dynamic fluid-loss conditions. This report provides experimental leak-off results for linear guar gels and for N2-guar foam-based fracturing fluids under a wide range of fracturing conditions. In particular, the effects of the rock permeability, the foam quality, and the pressure drop are investigated. Analysis of dynamic leak-off data provide an understanding of the complex mechanisms of viscous invasion and filter-cake formation occurring at the pore-scale. This study presents data supporting the superior fluid-loss behavior of foams, which exhibit minor liquid invasion and limited damage. It also shows direct measurements of the ability of the gas component to leak-off into the invaded zone, thereby increasing the gas saturation around the fracture and enhancing the gas productivity during flowback. Our conclusions not only confirm, but add to the findings of McGowen and Vitthal (1996) for linear gels, and the findings of Harris (1985) for nitrogen foams. / text

published_or_final_version / Mechanical Engineering / Master / Master of Philosophy

UCP1 is a member of the mitochondrial transmembrane anion carrier protein superfamily and is required to mediate adaptive thermogenesis in brown adipose tissue (BAT). Once activated, UCP1 uncouples mitochondrial respiration from ATP synthesis, thereby wasting the protonmotive force formed across the mitochondrial inner membrane as heat. It is hypothesized that proton leaks through UCP1 could be a molecular target to combat certain forms of obesity. Although it is well established that UCP1 is regulated by allosteric mechanisms, alternative methods such as post-translational modification still remain to be explored. The aims of the present study were to confirm the phosphorylation of UCP1 and the physiological relevance of this modification. Using isoelectric focusing, we confirmed that UCP1 displayed acidic shifts consistent with phosphorylation in BAT mitochondria isolated from cold exposed versus warm acclimated mice. A mouse model that ectopically expressed UCP1 in skeletal muscle was used to explore the link between the mitochondrial redox status and UCP1 function. Our results show that the expression of UCP1 in skeletal muscle led to decreases in body and tissues weights. In contrast, glucose uptake into skeletal muscle, food intake and energy expenditure was increased with the expression of UCP1. Finally, proton leaks through UCP1 were determined to be increased in isolated mitochondria from transgenic versus wild-type mice. Taken together these results indicate a complex interplay between mitochondrial redox status, post-translational modification and UCP1 function. Elucidation of novel mechanisms regulating UCP1 offers alternatives strategies that can be explored in order to modulate BAT thermogenesis.

Thesis (M. Phil.)--University of Hong Kong, 2000. / Includes bibliographical references (leaves 187-190).

L’AE1 (SLC4A1) est un échangeur chlorure/bicarbonate. Cette protéine est la protéine membranaire la plus abondante à la surface des globules rouges des vertébrés. Elle est participe au transport du CO2 et à l’ancrage du cytosquelette à la membrane plasmique. Des mutations ponctuelles dans la partie membranaire de l’AE1, liées à des pathologies humaines, convertissent l’échange électroneutre en voie de conductance pour le sodium et le potassium ou induisent une fuite de cations dans un échangeur d’anions toujours fonctionnel. Les déterminants moléculaires qui induisent les mouvements d’ions au travers de cet échangeur sont encore inconnus. Le travail présenté a eu pour but d’identifier et de cartographier le site de transport de la protéine normale ou « pathologique ». Nous avons adapté à l’AE1 des outils basés sur la chimie des sulfhydriles capable de donner des informations sur le rôle d’acides aminés dans le site de transport de la protéine. Cette stratégie combinée à l’élaboration d’un modèle tridimensionnel de la protéine in silico basé sur le symporteur uracile/proton nous a permis de définir le site de transport de l’AE1. Nos résultats démontrent qu’un site de transport unique dans l’AE1 peut basculer entre 3 conformations différentes : échange chlorure/bicarbonate, fuite de cation et échange anionique ou fuite de cation uniquement. Ce site met en jeu les segments transmembranaires (TM) 3, 5 et 8 ainsi qu’une boucle intracellulaire très conservée située entre les TM 8 et 9. Le site de transport se structure autour des acides aminés L468, F471, L530, I533 et L673 se terminant au niveau du E681. La boucle intracellulaire 690 à 705 agissant comme un filtre à cations. / AE1 (SLC4A1, band 3) is a member of the SLC4 bicarbonate transporter family. This protein is the most abundant membrane protein on the surface of vertebrate red blood cells. The AE1 exchanges chloride and bicarbonate ions in physiological conditions. In red blood cells, it is essential to many tasks including CO2 transport and cytoskeleton anchoring in the plasma membrane. Point mutations in the membrane spanning domain of AE1 convert the electroneutral exchange into a conductance for sodium and potassium cations or induce a cation leak in a still functional anionic exchanger.The molecular determinants that induce the movement of ions through the exchanger are still unknown. This work aims at identifying and mapping the transport site of AE1 protein in normal and pathological conditions. We modified a sulfhydryl-based chemistry to AE1. This provided information on the role of amino acids in the transport site of the protein. This strategy combined with the development of a three-dimensional model of the protein in silico, based on the uracil/proton symporter, allowed us to define the transport site of AE1. Analysis of our results showed that a single transport site in AE1 can switch between three different conformations depending on protein mutation: classical chloride/bicarbonate exchange, cation leak and anion exchange, cation leak only. The transport site involves the transmembrane segments 3, 5 and 8 and a highly conserved intracellular loop between transmembrane segments 8 and 9. The transport site is centered around the amino acids L468, F471, L530, L673, I533 and ends at glutamic acid 681. The intracellular loop 690-705 acts as a cation filter.

Made available in DSpace on 2014-12-17T15:03:20Z (GMT). No. of bitstreams: 1 DanielMMG_capa_ate_cap5.pdf: 2872095 bytes, checksum: d55fa9a7b43ef3592993ec83a2ef30e5 (MD5) Previous issue date: 2008-09-04 / This paper presents a study on coastal hydrodynamics and the spread of an oil spill in waters off Macau and Galinhos, on the east coast of the state of Rio Grande do Norte in Northeast Brazil. This area has a very marked coastal dynamic owing to the complexity of its geomorphological features, developed in a regime of semidiurnal mesotides involving reefs, spits, estuaries, mangroves, lakes and dunes. The region also plays an important role in the socioeconomic development of the state, given that the production of oil, natural gas, salt and shrimp is concentrated there. The series of oil platforms is interconnected by a pipeline system that carries oil to the local terminal. This pipeline could leak at any moment, causing immense ecological damage. To gauge the risks of an oil leak and resulting contamination of the coastal region, two hydrodynamic scenarios were simulated. The results obtained were used to implement a contaminant transport model with the creation of various oil leak scenarios modeled at different volumes (from small to large) and intensities (sporadic and continuous), at points considered critical for the model (on two platforms and at two pipeline intersections), under different wind (summer and winter) and tidal (high and low at new, full and quarter moon phases) conditions. The use of hydrodynamic circulation computer models as a tool for representing a real project design has been increasingly frequent in recent years, given that they enable the realistic simulation of the hydrodynamic circulation pattern in bodies of water and an analysis of the impacts caused by contaminants released into the water. This study used the computer models contained in SisBAHIA?, in continuous development in the area of Coastal Engineering and Oceanography at COPPE/UFRJ / Esta disserta??o apresenta um estudo sobre a hidrodin?mica costeira e a dispers?o da nuvem contaminante de ?leo na regi?o frontal a Macau e Galinhos, no litoral setentrional do Estado do Rio Grande do Norte no Nordeste do Brasil. Essa regi?o apresenta uma din?mica costeira muito acentuada devido a uma complexidade em suas fei??es geomorfol?gicas, desenvolvidas em regime de mesomar?s semidiurnas, que apresenta praias, recifes, spit, estu?rios, mangues, lagoas e dunas. A regi?o tamb?m possui um papel importante no desenvolvimento s?cio-econ?mico do Estado, por concentrar a produ??o de petr?leo e g?s natural, sal e, mais recentemente, a carcinicultura. O conjunto de plataformas petrol?feras ? interligado por dutos que levam o ?leo para o P?lo Petrol?fero localizado na regi?o e que podem a qualquer instante apresentar um vazamento que pode tomar propor??es de grande estrago ecol?gico. Para que os riscos de vazamento e contamina??o da regi?o praial fossem levantados, dois cen?rios hidrodin?micos foram simulados. Os resultados obtidos foram utilizados na implementa??o de um modelo de transporte de contaminantes com a cria??o de v?rios cen?rios de vazamentos modelados em diferentes volumes (de pequeno e grande porte) e intensidades (pontuais e cont?nuos), em pontos tomados como cr?ticos para o modelo (em duas plataformas e em duas interse??es de dutos), em diversas condi??es de ventos (ver?o e inverno) e mar?s (preamar e baixamar de siz?gia e de quadratura). A utiliza??o de modelos computacionais de circula??o hidrodin?mica como ferramenta para a representa??o de uma situa??o real de projeto tem sido cada vez mais freq?ente nos ?ltimos anos, visto que eles possibilitam a simula??o, com bastante realismo, do padr?o de circula??o hidrodin?mica em corpos d ?gua e analisam os impactos causados por lan?amentos de contaminantes na ?gua. Neste trabalho utilizou-se os modelos computacionais contidos no SisBAHIA?, em desenvolvimento continuado na ?rea de Engenharia Costeira e Oceanogr?fica da COPPE/UFRJ

No processo de abastecimento de Ãgua por meio de redes de distribuiÃÃo de Ãgua podem acontecer perdas do recurso hÃdrico associadas a vÃrias causas, tais como: vazamentos, erros de mediÃÃo e consumos nÃo autorizados. Com o avanÃo da informÃtica modelos matemÃticos cada vez mais complexos tÃm possibilitado o surgimento de tÃcnicas avanÃadas nas questÃes relacionadas ao projeto e dimensionamento Ãtimo de redes de distribuiÃÃo de Ãgua, incluindo, por exemplo, a tÃcnica de identificaÃÃo de vazamentos. O mÃtodo empregado na soluÃÃo do problema inverso à a utilizaÃÃo de dados transientes para calibraÃÃo do vazamento por meio do algoritmo genÃtico (MTI-AG) e para soluÃÃo das equaÃÃes diferenciais parciais do movimento para escoamento do transiente à usado o mÃtodo das caracterÃsticas (MOC). Nas 3 redes em estudo à analisado o efeito da severidade do transiente provocada por mudanÃas no tipo de manobra de vÃlvula, onde vÃrias simulaÃÃes foram feitas e comparados os resultados com as condiÃÃes permanentes iniciais, mostrando a eficiÃncia do mÃtodo empregado. / In the process of water supply through water distribution networks can happen losses of water resources associated with various causes, such as leaks, metering errors and unauthorized consumption. With the advancement of computer mathematical models increasingly complex have allowed the emergence of advanced techniques in matters relating to the design and optimal design of water distribution networks, including, for example, leak identification technique. The method used to solve the inverse problem is the use of transient data for calibration leak through genetic algorithm (MTI-AG) and for solution of partial differential equations of motion for the flow of the transient is used the method of characteristics (MOC) . In the three networks in study analyzes the transient severity of the effect caused by changes in the type of valve maneuver where several simulations were performed and compared the results with the initial permanent conditions, showing the method employed efficiency.

Orientador: Carlos Takahiro Chone / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-18T05:37:15Z (GMT). No. of bitstreams: 1 Sampaio_MarceloHamilton_D.pdf: 2255683 bytes, checksum: 64e5351d5d01506d6f0127054945558d (MD5) Previous issue date: 2010 / Resumo: Introdução: A Fístula liquórica da base anterior do crânio é a comunicação anormal entre a cavidade nasal ou os seios paranasais e o espaço subaracnóideo. Sua presença aumenta a incidência de complicações, como principalmente a meningite, com riscos de morte ou de seqüelas, como surdez, déficits motores e cognitivos. O diagnóstico precoce e correto da fistula liquórica é importante para que o tratamento cirúrgico seja realizado o mais brevemente possível. A detecção de liquor em fluidos nasais é realizada como método diagnóstico da fistula liquórica e baseia-se na pesquisa de proteínas específicas do líquor em secreções nasais, e pode ser feita através da pesquisa da ß2-transferrina, um teste imunológico caro e pouco disponível no Brasil. Recentemente foi descrita a quantificação nefelométrica da proteína ß-trace para a identificação da fístula liquórica, uma proteína específica do cérebro e presente em altas concentrações no líquor. Os dados da literatura sugerem a mesma sensibilidade e especificidade que a ß2-transferrina. Grande parte dos laboratórios de análises clínicas possuem o equipamento nefelômetro para a quantificação da proteína ß-trace. Objetivo: Determinar o valor de corte para a medida da concentração da proteína ß-trace e a previsibilidade do teste em confirmar ou não a presença de fístula liquórica em secreções nasais no dois lados da cavidade nasal. Métodos: Secreção nasal foi coletada de pacientes com suspeita de fístula liquórica e de voluntários saudáveis. Amostras de liquor puro foram usadas. O teste nefelométrico foi utilizado para determinar a concentração da proteína ß-trace nas amostras. Os achados durante a cirurgia endonasal endoscópica foram o padrão ouro para o diagnóstico da fístula liquórica. RESULTADOS: Foi encontrado um valor de corte entre 0,244 e 0,496 mg/L. Os valores preditivos positivo e negativo foram de 100%. As médias de concentração de proteína ß- trace no lado nasal acometido foram maiores que as médias de concentração de proteína ß- trace no lado nasal não acometido, com diferença estatisticamente significante. Conclusão: Concentrações de proteína ß-trace acima de 0,496 mg/L são altamente sugestivas da presença de liquor nas secreções nasais examinadas. O teste nefelométrico da proteína ß-trace pode prever o lado nasal acometido pela fístula liquórica. O teste da proteína ß-trace é uma boa / Abstract: Background: Cerebrospinal fluid (CSF) leak of the anterior skull base is an abnormal communication between the subarachnoid space and the nasal cavity or the paranasal sinus. Its presence increases the incidence of complications, as meningitis, with risk of sequels. The early and correct diagnosis of the CSF leaks is important in order to perform surgical treatment as soon as possible. The CSF detection in nasal fluids is performed as a diagnostic method of CSF leak, based on the detection of brain-specific proteins in nasal fluids, and could be made through the ß2-transferrin test, an expensive immunological test, not available to the majority of the Brazilian hospitals. Recently, the detection of ß-trace protein for identification of CSF leaks has been described. Literature data suggests the same sensibility and specificity to the ß2-transferrin, because ß-trace protein is also a specific brain protein and it is present in CSF in high concentrations. The majority of Brazilian laboratories of clinical analysis have the nephelometric equipment for ß-trace protein detection. Objective: To determine threshold values for ß-trace protein concentrations in nasal cavity secretions as a predictor of CFS leak. Methods: Nasal secretions were collected from patients with suspicion of CSF leak and from healthy volunteers. Pure CSF samples were used. A nephelometric assay was used to determine the ß-trace protein concentration in samples. The gold standard diagnostic method was the surgery. Results: Values between 0.244 and 0.496 mg/L were determined for the cut-off. Positive predictive value and negative predictive value were 100%. The concentration in the affected side were higher than the contralateral side. Conclusion: ß-trace concentrations above 0.496 mg/L are highly suggestive of the presence of cerebrospinal fluid in examined nasal secretion. ß-trace protein nephelometric test can predict the side of the CSF leak. The ß-trace protein test is a good alternative for the detection of CSF leak in Brazilian hospitals / Doutorado / Otorrinolaringologia / Doutor em Ciências Médicas

Esta avaliação buscou validar a técnica de retrabalho utilizada no processo de fabricação de evaporadores automotivos, onde a falha na operação de brasagem e tratamento térmico é um dos principais motivos para o alto índice de sucata. A técnica de retrabalho consiste em refazer a operação de brasagem e tratamento térmico nos evaporadores que apresentaram falhas no teste de estanqueidade. Os evaporadores foram submetidos ao processo de rebrasagem em forno de brasagem NOCOLOK e o tratamento superficial em forno de tratamento térmico e avaliados por meio de teste de estanqueidade, utilizando-se gás Hélio (He) à pressão de 16bar e ensaio metalográfico comparativo entre peças produzidas com o ciclo normal de brasagem e tratamento térmico e com o ciclo de rebrasagem, avaliando as modificações nas juntas brasadas. Os resultados obtidos nos 05 experimentos demonstraram que houve modificações significativas nas juntas brasadas após os evaporadores terem sidos submetidos ao processo normal de brasagem, seguido de mais 04 ciclos de rebrasagem e tratamento térmico. Portanto, para a fabricação dos evaporadores automotivos fica recomendado a execução de brasagem e no máximo uma rebrasagem, eliminando a possibilidade de execução de novas rebrasagens. / This evaluation sought the validation of the rework technique used in automotive evaporators manufacturing, where this failure on brazing operation is a main reason to high level of scrap. The rework technique consists in redoing the brazing operation and thermal treatment on evaporators which fail the leak test. The evaporators were subjected to rebrazing process in NOCOLOK furnace and surface treatment in thermal treatment furnace and evaluated through leak test device, using Helium (He) at 16bar of pressure and metallographic test to compare normally produced parts with rebrazing ones, evaluating the structural changes of the material. The results got from 05 experiments made showed that there were significant changes in the brazing joint, after the evaporators being subjected to the normal brazing process, followed by 04 more rebrazing cycles and thermal treatment. Therefore, for the automotive evaporators manufacturing the brazing execution is recommended and at the most a rebrazing, eliminating the possibility of execution of new rebrazing.

A ocorrência de elevados índices de perdas por vazamentos em sistemas de abastecimento de água é frequentemente ligada às inúmeras quebras de tubulações originadas em decorrência de elevados níveis de pressão atuantes. O controle efetivo de tais perdas requer a detecção e localização dos vazamentos para uma rápida reparação do sistema. Neste sentido, a consideração de análises hidráulicas no escoamento transitório tem se revelado especialmente útil aos propósitos de calibração e detecção de vazamentos. Tal análise pode revelar substancial quantidade de informações sobre as propriedades físicas e o nível de integridade do sistema, pois as ondas de pressão resultantes são afetadas pelos diversos dispositivos e fenômenos, incluindo os vazamentos. Assim, o presente trabalho visa o estudo dos transitórios hidráulicos para a calibração e detecção de vazamentos em modelos de sistemas de distribuição de água. Para tanto, são utilizados dados de redes hipotéticas e de laboratório, e modelos inversos resolvidos por métodos de busca global e local. Devido o emprego de tubos plásticos no circuito de laboratório, o clássico modelo da coluna elástica demonstrou-se ineficiente na reprodução do comportamento hidráulico de tal sistema. Resultados satisfatórios foram obtidos somente com um modelo hidráulico que considere o comportamento viscoelástico dos materiais dos tubos do circuito experimental. / The occurrence of large leakage losses in water supply systems has been frequently linked with pipe breaks resulting from high pressures levels in pipes. Efficient location of leakages is required in order to effectively control water losses and quickly repair the system. Analysis of hydraulic transients has been particularly useful for calibration and leak detection purposes. System observation for such analysis can reveal a substantial amount of information concerning physical properties and the integrity of the system, since water hammer waves are affected by different features and phenomena, including leaks. Thus, this research focuses on hydraulic transients for leak detection and calibration of water distribution system models. These objectives are achieved using data obtained from experiments performed on an experimental facility and numerical experiments on hypothetical networks. Inverse methods were based on both global and local search methods. Classic water hammer theory proved to be imprecise in describing the observed behavior of the hydraulic system composed of plastic pipes. Satisfactorily results were obtained with a hydraulic transient solver considering viscoelastic behavior of the pipe material.