661 resultados para Suspensões de cristais
Resumo:
The partial fixed prosthodontics restoration is used to rehabilitate form and function of partial or total compromised teeth, having to remain permanently joined to remainder tooth. The most useful material on prosthodontics is the feldspar porcelain, commercialized as aluminosilicate powders. Dental porcelains are presented with limited mechanical properties to rehabilitate extensive spaces. The association with Ni-Cr metallic systems (metal-ceramic system) allows that the metallic substructure compensates the fragile porcelain nature, preserving the thermal insulation and aesthetics desirable, as well as reducing the possibility of cracking during matication efforts. Cohesive flaws by low mechanical strength connect the metallic substructure to the oral environment, characterized by a electrolytic solution (saliva), by aggressive temperature, pH cyclic changes and mechanical requests. This process results on ionic liberation that could promote allergic or inflammatory responses, and/or clinical degradation of ceramometal system. The aim of this study was to evaluate the presence of an intermediate titanium layer on the microscopic fracture behavior of porcelains on ceramometal systems. Plasma deposition of titanium films result in regular passivating oxide layers which act as barriers to protect the metallic substrate against the hazardous effects of corrosive saliva. Tribocorrosion tests were performed to simulate the oral environment and mechanical stress, making it possible the early detection of crack formation and growth on metal-ceramic systems, which estimate the adherence between the compounds of this system. Plain samples consisting of dental feldspar porcelain deposited either onto metallic substrates or titanium films were fired and characterized by scanning electron microscopy. The result showed that the titanium film improved the adherence of the system compared to conventional metal-ceramic interfaces, thus holding crack propagation
Resumo:
In view of a field research carried out by a team connected to the universe of body modification, it is possible to discern some uses and meanings linked to these forms of body interventions. Body modification or body change is part of the circuit of piercings and tattoos, although they are socially less thinned and more extreme, like scarifications, subcutaneous implants, bifurcated tongues, surfaces and body suspensions. The aim of this paper is to cast an anthropological glance on these practices, joining at the same context all the subjects involved with these techniques, placing them inside the same relational focus and capturing their journeys and trajectories. The discussions are concentrated on the notion of body building and urban life style. Ideas as personal distinctness and prestige imitation are also present in this universe, as well as matters attached to genre, pleasure, art, and to the so-called alternative circuit . This way, the ethnography so far presented here, reveals the complex and contemporaneous character of these practices of body markings in which the body appears as the central element in the experiences of the subjects of this study
Resumo:
Dissertação de Mestrado, Ciências Biomédicas, Departamento de Ciências Biomédicas e Medicina, Universidade do Algarve, 2014
Resumo:
Dissertação mest. em Imagiologia Médica, Faculdade de Ciências e Tecnologia da Univ. do Algarve, 2006
Resumo:
The environmental impacts, caused by the solid residues generation, are an often quoted concern nowadays. Some of these residues, which are originated from different human activities, can be fully reused, reducing the effects of the poor waste management on the environment. During the salt production process, the first formed crystals are discarded as industrial waste. This is mainly made of gypsum that is a calcium sulfate dihydrate (CaSO4.2H2O). The gypsum in question may go through a calcination process due to the plaster (CaSO4.0,5H2O) production and then the application on the cement industry. Considering the necessity of development and application for these industrial wastes, this paper aims to analyze the plaster, called Salgesso, from the gypsum that was generated during the salt production, and its use viability on the civil construction industry in order to create environmental and economical benefits. For characterization, the following experiments were performed: X-ray Fluorescence (XRF), X-ray Diffraction (XRD), thermal analysis (TG/DTG) and Scanning Electron Microscopy (SEM) with EDS. The following tests were also performed to obtain the mechanical characteristics: Thinness Modulus, Unit Mass, Setting Time and Compressive Resistance. Three commercial plasters used on civil construction were taken as references. All of these tests were performed according to the current standards. It was noticed that although there were some conflicting findings between the salt and commercial plasters in all of the studied properties, the Salgesso has its values within the standard limits. However, there is the possibility to improve them by doing a more effective calcination process. Three commercial plasters, used in construction, were used as reference material. All tests were performed according to standards in force. It was observed that although some tests present conflicting findings between the salt and gypsum plasters commercial properties in all of the studied Salgesso have values within the limits imposed by the standard, but can be improved simply by calcination process more effective
Resumo:
Avaliou-se o efeito de Metarhizium anisopliae (Metsch.) para Astyanax scabripinnis (Jenyns, 1842)(Pisces, Characidae), em condições de laboratório. Suspensões aquosas de conídios recémproduzidos, viáveis (viabilidade mínima 90%) e inviabilizados por meio de autoclavagem (121º C, 20 minutos, a 1 atm), na concentração de 6,5 x 1010 conídios/aquário (equivalente a 5 x 1015 conídios/ ha, que representa 1.000 vezes a concentração recomendada para o controle de cigarrinhas de pastagens, principal praga-alvo deste entomopatógeno no Brasil), foram aplicadas em aquários contendo A. scabripinnis. Foram analisadas amostras de água e dos peixes, dos quais foram dissecados as brânquias e o estômago, em diferentes intervalos de tempo, a fim de se avaliar a presença dos conídios. Observaram-se diariamente o comportamento e a mortalidade de peixes em ambos os tratamentos. Avaliou-se nos peixes sobreviventes a morfologia das células das brânquias e do fígado. Verificou-se que nas brânquias não houve alteração no número de conídios ao longo de 16 dias de contato, sendo que no estômago houve um ligeiro acréscimo inicial seguido de redução constante. A viabilidade dos conídios em todos os locais avaliados decresceu após 24 horas da aplicação. Constatou-se que não houve morte ou quaisquer alterações comportamentais após 30 dias de contato, indicando a ausência de efeitos adversos associados à capacidade do fungo em provocar infecção ou exercer efeitos tóxicos em ambos os organismos-teste.
Resumo:
Deep bed filtration occurs in several industrial and environmental processes like water filtration and soil contamination. In petroleum industry, deep bed filtration occurs near to injection wells during water injection, causing injectivity reduction. It also takes place during well drilling, sand production control, produced water disposal in aquifers, etc. The particle capture in porous media can be caused by different physical mechanisms (size exclusion, electrical forces, bridging, gravity, etc). A statistical model for filtration in porous media is proposed and analytical solutions for suspended and retained particles are derived. The model, which incorporates particle retention probability, is compared with the classical deep bed filtration model allowing a physical interpretation of the filtration coefficients. Comparison of the obtained analytical solutions for the proposed model with the classical model solutions allows concluding that the larger the particle capture probability, the larger the discrepancy between the proposed and the classical models
Resumo:
The general objective of this study was to contribute to the understanding of the chemical evolution of fluids that percolate through carbonate rocks of the Jandaíra Formation. The oxidation and reduction conditions in which grains, source and cement were formed was investigated using the cathodoluminescence technique (CL). The study area is located in the west part of the Potiguar Basin (Fazenda Belém field) and Rosário Ledge (Felipe Guerra municipality, State of Rio Grande do Norte, Brazil). The analysis of thin sections of carbonate rocks under CL revealed that grains (allochemical or not) and diagenetic products (micritization, dolomitization, neomorphism and cementation) exhibit since absence of luminescence the various luminescence colors (yellow, orange, red, brown, and blue) in a variety of intensities. As pure calcite shows dark blue luminescence, the occurrence of different luminescence colors in calcite crystals suggest one or more punctual crystal defects such as free electron, free space and impurity. The dyeing of thin sections with alizarin and potassium ferrocyanide revealed the absence of ferrous carbonate in the different lithotypes of Jandaíra Formation. Therefore, the different colors and intensities of CL observed in these rocks are probably caused by the presence of ion activators such as Mn2+ and is not an activator/inhibitor combination. In the same way, the absence of luminescence is very probably caused by the absence of activator ions and not due to the low concentration of inhibitor ions such as Fe2+. The incorporation of Mn2+ in the different members of the Jandaíra Formation must have been controlled by the redox state of the depositional environment and diagenesis. Therefore, it is possible that the luminescent members have been formed (e.g.,ooids) or have been modified (gastropod neomorphism) under reduction conditions in the depositional environments, in subsurface during the burial, or, in the case of Rosario Ledge samples , during the post-burial return to surface conditions. As regards the sudden changes from low to moderate and to strong luminescence, these features should indicate the precipitation of a fluid with chemical fluctuations, which formed the frequent zonations in the block cement of the Rosario Ledge samples. This study suggests that the different intensities and colors of CL should be correlated with the Mn2+ and Fe2+ contents, and stable isotopes of samples to determine the salinity, temperature, pH e Eh conditions during deposition
Resumo:
Injectivity decline, which can be caused by particle retention, generally occurs during water injection or reinjection in oil fields. Several mechanisms, including straining, are responsible for particle retention and pore blocking causing formation damage and injectivity decline. Predicting formation damage and injectivity decline is essential in waterflooding projects. The Classic Model (CM), which incorporates filtration coefficients and formation damage functions, has been widely used to predict injectivity decline. However, various authors have reported significant discrepancies between Classical Model and experimental results, motivating the development of deep bed filtration models considering multiple particle retention mechanisms (Santos & Barros, 2010; SBM). In this dissertation, inverse problem solution was studied and a software for experimental data treatment was developed. Finally, experimental data were fitted using both the CM and SBM. The results showed that, depending on the formation damage function, the predictions for injectivity decline using CM and SBM models can be significantly different
Resumo:
Modeling transport of particulate suspensions in porous media is essential for understanding various processes of industrial and scientific interest. During these processes, particles are retained due to mechanisms like size exclusion (straining), adsorption, sedimentation and diffusion. In this thesis, a mathematical model is proposed and analytical solutions are obtained. The obtained analytic solutions for the proposed model, which takes pore and particle size distributions into account, were applied to predict the particle retention, pore blocking and permeability reduction during dead-end microfiltration in membranes. Various scenarios, considering different particle and pore size distributions were studied. The obtained results showed that pore blocking and permeability reduction are highly influenced by the initial pore and particle size distributions. This feature was observed even when different initial pore and particle size distributions with the same average pore size and injected particle size were considered. Finally, a mathematical model for predicting equivalent permeability in porous media during particle retention (and pore blocking) is proposed and the obtained solutions were applied to study permeability decline in different scenarios
Resumo:
Dissertação (mestrado)—Universidade de Brasília, Faculdade de Agronomia e Medicina Veterinária, Programa de Pós-Graduação em Saúde Animal, 2016.
Resumo:
O presente relatório tem como propósito a obtenção de grau de mestre em Educação PréEscolar e Ensino do 1.º Ciclo do Ensino Básico. Para tal neste encontra – se incluído os pressupostos teóricos e metodológicos que fundamentam a minha prática pedagógica. A minha intervenção na vertente Pré-Escolar foi realizada com um grupo de crianças com idades compreendidas entre os três e os seis anos, da Sala dos Cristais na EB1/PE da Achada. Na vertente de 1.º Ciclo do Ensino Básico intervim com a turma do 2º B da EB1/PE da Pena. Durante a prática pedagógica foi utilizada a investigação-ação como metodologia essencial que permite ao professor ter o papel de investigador ao refletir sobre o processo de ensino-aprendizagem. No decorrer dos estágios pedagógicos foram desenvolvidas duas problemáticas. No 1º ciclo surgiu a problemática: Como utilizar uma aprendizagem cooperativa na sala de aula? E no Pré-Escolar a problemática intitulou-se: Como melhorar as competências sociais e afetivas no Pré-escolar? A utilização da investigação permitiu a implementação de estratégias com o intuito de proporcionar aprendizagens de melhor qualidade. Para abordar esta metodologia recorri à observação participante para desenvolver estratégias com o intuito de estimular, respeitar os seus ritmos e os modos de aprendizagem de cada um, tendo sempre em conta as suas necessidades e os interesses das crianças. Este relatório relata todo o percurso realizado nas duas vertentes pedagógicas sendo também um instrumento de reflexão de todo o processo dando continuidade à construção de uma identidade profissional.
Resumo:
O presente relatório tem como propósito a obtenção de grau de mestre em Educação PréEscolar e Ensino do 1.º Ciclo do Ensino Básico. Para tal neste encontra – se incluído os pressupostos teóricos e metodológicos que fundamentam a minha prática pedagógica. A minha intervenção na vertente Pré-Escolar foi realizada com um grupo de crianças com idades compreendidas entre os três e os seis anos, da Sala dos Cristais na EB1/PE da Achada. Na vertente de 1.º Ciclo do Ensino Básico intervim com a turma do 2º B da EB1/PE da Pena. Durante a prática pedagógica foi utilizada a investigação-ação como metodologia essencial que permite ao professor ter o papel de investigador ao refletir sobre o processo de ensino-aprendizagem. No decorrer dos estágios pedagógicos foram desenvolvidas duas problemáticas. No 1º ciclo surgiu a problemática: Como utilizar uma aprendizagem cooperativa na sala de aula? E no Pré-Escolar a problemática intitulou-se: Como melhorar as competências sociais e afetivas no Pré-escolar? A utilização da investigação permitiu a implementação de estratégias com o intuito de proporcionar aprendizagens de melhor qualidade. Para abordar esta metodologia recorri à observação participante para desenvolver estratégias com o intuito de estimular, respeitar os seus ritmos e os modos de aprendizagem de cada um, tendo sempre em conta as suas necessidades e os interesses das crianças. Este relatório relata todo o percurso realizado nas duas vertentes pedagógicas sendo também um instrumento de reflexão de todo o processo dando continuidade à construção de uma identidade profissional.
Resumo:
O pinhão, sementes de Araucaria angustifolia, tem o amido como componente principal. Os amidos oxidados melhoram as características físico-química, de pasta e térmicas dos produtos em processos industriais. O amido de pinhão nativo foi tratado com soluções padronizadas de permanganato de potássio (KMnO4) e as amostras foram analisadas por técnicas termoanalíticas (TG-DTA) em atmosfera inerte. As amostras foram oxidadas da seguinte forma: quatro porções de 20 g (base seca) foram separadas e três foram suspensas em solução de KMnO4 (0,001; 0,002; 0,005 mol L-1) em agitação constante durante 30 minutos, a quarta amostra foi mantida como recebida. As suspensões de amido foram filtradas, lavadas, secas e analisadas. As modificações oxidativas provocaram mudanças estruturais das moléculas de amido, registradas pelos diferentes resultados calculados a partir das curvas TGA e DTA. A amostra (3) teve as mudanças mais significativas na degradação com o 3ª evento exotérmico com temperaturas acima de 330 °C.
Resumo:
Os efeitos dos extratos clorofórmico de folhas de tagetes minuta e etanólico de folhas de Vernonia condensata foram avaliados sobre a germinação de uredosporos de hemileia vastatrix. Gotas das suspensões dos extratos foram colocadas sobre laminas de vidro, sendo a seguir adicionada determinada quantidade de uredosporos de Hemileia vastatrix. Após 6 horas de incubação com umidade relativa de aproximadamente 100% e escuro, foi efetuada a avaliação através de contagem de uredosporos germinados. Para as concentrações de 1, 10, 100, 1000 e 10000 ppm de extrato de V. condensata as porcentagens de inibição dos uredosporos de H. vastatrix foram de 24, 40, 63, 71 e 96%, respectivamente. Para o extrato de T. minuta foram de 21, 71, 86, 91 e 96%, respectivamente.