Negative Thermal Expansion
Mostrando 1-12 de 14 artigos, teses e dissertações.
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1. Physicomechanical and thermal analysis of bulk-fill and conventional composites
Abstract The aim of this study was to evaluate the degree of conversion (DC) and the thermal stability of bulk-fill and conventional composite resins. Eleven composite resin samples were prepared to evaluate the DC, Vickers microhardness (VMH), mass and residue/particle loss, glass transition temperature (Tg), enthalpy, and linear coefficient of thermal expa
Braz. oral res.. Publicado em: 18/03/2019
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2. Avaliação de diferentes potenciais interatômicos no cálculo do tensor de elasticidade do tungstato de zircônio
O Tungstato de Zircônio (ZrW2O8) é um material que exibe Expansão Térmica Negativa (ETN), isotrópica em um amplo intervalo de temperatura (0,3 a 1050 K). Apesar de amplamente estudado, existem controvérsias acerca dos mecanismos microscópicos responsáveis por este comportamento. A fase cúbica deste composto, denominada a-ZrW2O8, já foi motivo de es
Publicado em: 2009
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3. Atomistic simulations of supercooled gallium / Simulações atomisticas do galio super-resfriado
Recently, the existence of a liquid-liquid transition in pure substances has been proposed as an explanation of anomalous behaviors such as the increase of response functions (isothermal compressibility, coefficient of thermal expansion, specific heat) with decreasing temperature displayed by some liquids. The existence of this type of transition has been de
Publicado em: 2009
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4. Eutrophication of Cruzeta reservoir in the representative basin of the Seridó river - RN. Natal / Eutrofização do Reservatório Cruzeta na bacia representativa do rio Seridó RN
Eutrophication has been listed as one of the main problems of water pollution on a global level. In the Brazilian semi-arid areas this problem takes even greater proportions due to characteristical water scarcity of the region. It is extremely important to the predictive eutrophication models development and to the reservoirs management in the semi-arid regi
Publicado em: 2008
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5. SÍNTESE E CARACTERIZAÇÃO DE ÓXIDOS COM BAIXA EXPANSÃO TÉRMICA / SYNTHESIS AND CHARACTERIZATION OF LOW THERMAL EXPANSION OXIDES
Negative and low thermal expansion materials have important potential applications as resistance to thermal shock, as well as, for odontological applications, printed circuit boards, optical components and to produce composites to compensate the positive thermal expansion of materials. For this reason, the study and production of materials with controlled th
Publicado em: 2007
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6. Expansão térmica sintonizável do ZrW2O8
Zirconium tungstate (a-ZrW2O8) exhibits isotropic negative thermal expansion over a wide range of temperature. Under high-pressures this material transforms to a metastable amorphous phase (a-ZrW2O8). a-ZrW2O8 can be fully recovered by annealing the amorphous phase at temperatures slightly above 600oC, at room pressure. The amorphous phase, in principle, sho
Publicado em: 2007
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7. Estrutura e propriedades elásticas das fases alpha e gama do ZrW2O8
The crystalline structure and some elastic properties of the alpha and gamma phases of zirconium tungstate, ZrW2O8, were calculated according to Density Functional Theory using the B3LYP functional (DFT/B3LYP). The structure of alpha ZrW2O8, was optimized at different pressures and its elastic constants were estimates. The interatomic iterations, ranked in t
Publicado em: 2007
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8. Imobilização da enzima frutosiltransferase extracelular de Rhodotorula sp. e aplicação na produção de frutooligossacarideos. / Imobilization of extracellular enzyme fructosyltransferase from Rhodotorula sp. and application in fructooligosaccharides production.
Fructooligosaccharides (FOS) production by immobilized enzymes encloses two concepts that have faced great expansion in the last few years: industrial application of enzymes and functional foods. The option for enzyme immobilization is mainly induced by the easiness of controlling the reaction and the possibility of reusing the biocatalyst, besides the fact
Publicado em: 2007
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9. Filmes intermediários para deposição de diamantes CVD sobre aços / Intermediate films for diamond deposition on steel
The present work is inserted in the area of Chemical Vapor Deposition of Diamond thin and freestanding films. The CVD diamond deposition on steel substrates is still a great challenge to overcome. Iron-like materials present negative effects for the CVD diamond growth process, as catalytic effects in the preferential nucleation of the graphitic phase and hig
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 31/08/2006
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10. Thermal expansion contribution to the temperature dependence of excitonic transitions in GaAs and AlGaAs
Photoluminescence and photoreflectance measurements have been used to determine excitonic transitions in the ternary Al xGa1-xAs alloy in the temperature range from 2 to 300 K. The effect of the thermal expansion contribution on the temperature dependence of excitonic transitions for different aluminum concentrations in the Al xGa1-xAs alloy is presented. Re
Brazilian Journal of Physics. Publicado em: 2004-06
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11. Raman analyses of residual stress in diamond thin films grown on Ti6Al4V alloy
The stress evolution in diamond films grown on Ti6Al4V was investigated in order to develop a comprehensive view of the residual stress formation. Residual stress is composed of intrinsic stress induced during diamond film growth and extrinsic stress caused by the different thermal expansion coefficients between the film and substrate. In the coalescence sta
Materials Research. Publicado em: 2003-01
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12. Expansion of the host range of coliphage P1 and gene transfer from enteric bacteria to other gram-negative bacteria.
The bacterial host range of coliphage P1 was extented by using the heat-inducible phage P1clr100KM. A gene for kanamycin resistance was transferred from Escherichia coli to members of the family Enterobacteriaceae and some other genera of gram-negative bacteria. P1 phage was produced by thermal induction from the lysogens of all these kanamycin-resistant bac