384 resultados para Microscópio óptico


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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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This study aims to evaluate the corrosion resistance of Ti-30Ta alloy when subjected to different strain rates. Samples of the alloy Ti-30Ta were obtained from the melting of pure elements in the arc furnace in inert atmosphere (argon gas). Then, the samples were subjected to a thermal treatment and to cold worked to obtain bars. After forging, the samples were machined in accordance with ASTME9-09 standard for carried out compression tests. To microstructural characterization, samples were sectioned longitudinal and transversally and embedded in resin. After, the wet sanding and polishing were performed, followed by a chemical attack, in order to study the microstructure under an optical microscope. Microhardness was measured on the samples that were subjected to microstructural characterization by using microhardness tester. Phases were evaluated by x-rays diffraction. Corrosion tests were carried out to evaluate the influence of deformation on the corrosion resistance. Results show that microstructure was not influenced by deformation

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The machining process is so much important in the economic world. Many machining parameters have been studied to maximize results, in terms of cost and lifetime. (decrease of cutting tool wear, improved surface finish, among others). The objective of this study is to evaluate the wear of a ceramic tool in the machining of the aluminum alloy 6005 A. The analysis of the wear of the cutting tools is very important due to its big impact on the final finishing of the piece as a whole. The evaluation took place in two stages, first it was done a detailed study of the literature of the whole machining process, where the study of the formation and swarf classification were among the most important steps in this phase. The second step consisted in the machining of the piece of aluminum 6005 A with a ceramic cutting tool constituded of aluminum oxide and magnesium oxide with silicon carbide impregnation. The swarf generated in this process was then photographed with a Zeiss optical microscope and analyzed for its size and shape. Through this comparison it was concluded that the swarf are generated shear swarfs, shaped like a tangled, fragmented and arcs connected, thus classifying the material as medium difficulty machining. Through the image analysis tool it was concluded that the parameter of lower wear was the: Vc = 500m / min, f = 0.10mm / rev and ap = 0.5mm

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Foram estudados os aspectos morfológicos de nove placentas de paca (Agouti paca, L., 1766) mediante análises em microscopia de luz e eletrônica de transmissão dos fragmentos teciduais correspondentes à porção de maior conexão placentária em diferentes fêmeas gestantes, nos estágios intermediário e final da prenhez. Realizamos este estudo, pois, aliada à necessidade da procura de novas espécies que atuem como modelos experimentais adequados, havia a disponibilidade deste roedor em nosso meio; por outro lado, o melhor conhecimento dos aspectos reprodutivos destes animais oferece subsídios ao estabelecimento de criatórios racionais desta espécie, uma vez que a preservação deste vertebrado é necessária, além do grande interesse comercial em torno de sua carne. Os resultados mostraram que este roedor possui uma placenta do tipo vitelina e outra do tipo corioalantoidiana, sendo este órgão do tipo hemocorial, labiríntico, que se apresenta histologicamente composto por lóbulos divididos em três regiões distintas: o centro do lóbulo, o labirinto e o interlóbulo. Na região do centro do lóbulo, verificou-se a presença de artérias e veias; e em sua região periférica estavam presentes dois sistemas tubulares arranjados de forma paralela, onde as lacunas sangüíneas e os capilares estavam em íntimo contato, formando a região do labirinto. O interlóbulo era composto de artérias e veias. O trofoblasto era o principal componente da placenta, que, independentemente da região onde se encontrava, mostrava-se de natureza sincicial. Ultra-estruturalmente a barreira placentária da paca foi classificada como hemomonocorial.

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Avaliou-se a espessura corneana central de 13 gatos normais com microscópio especular de não-contato Topcon SP-2000P e paquímetro ultra-sônico. Foi observado aumento da espessura corneana mensurada pelo paquímetro ultra-sônico comparado ao microscópio especular.

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The morphology of the midgut epithelium cells of Anticarsia gemmatalis (Hübner) larvae is described by light and transmission electron microscopy. The midgut of A. gemmatalis is the largest portion of the digestive tract, with three distinct regions: proximal, media and distal. Its wall is formed by pseudostratified columnar epithelial tissue having four cell types: columnar, goblet, regenerative, and endocrine cells. The columnar cells are numerous and long, with the apical portion showing many lengthy microvilli and the basal portion invaginations forming a basal labyrinth. The goblet cells have a large goblet-shaped central cavity delimited by cytoplasmic projections filled with mitochondria. The regenerative cells present electron-dense cytoplasm and few organelles. The endocrine cells are characterized by electron-dense secretory granules, usually concentrated in the cytoplasm basal region.