Liquid Helium
Mostrando 1-12 de 39 artigos, teses e dissertações.
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1. Reduction of Aqueous Ag+ Steered by Electrochemical Plasma: Connecting the Bulk pH Variation with the Reaction Pathways for Hydrated Electrons
Reduction of silver cations followed by nanoparticle (Ag-NPs) synthesis is a model process to understand the reduction mechanism induced by a discharge over an aqueous surface, termed electrochemical plasma. This work aims at studying the silver reduction reaction steered by electrochemical plasma in the presence of other chemically active plasma-related int
J. Braz. Chem. Soc.. Publicado em: 23/05/2019
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2. Entropy variation in isothermal fluid flow considering real gas effects
Abstract The present paper concerns on the estimative of the pressure loss and entropy variation in an isothermal fluid flow, considering real gas effects. The 1D formulation is based on the isothermal compressibility module and on the thermal expansion coefficient in order to be applicable for both gas and liquid as pure substances. It is emphasized on the
J. Aerosp. Technol. Manag.. Publicado em: 2011-04
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3. Single-phase resistive superconductor electrical current limiter
This paper presents the analysis, design, construction and ac test results of low voltage single-phase resistive superconductor electrical current limiters. Two different types of resistive superconductor current limiter are presented: the first one is built with three concentric, cylindrical and helicoidal coils connected in parallel and the second one is b
Publicado em: 2011
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4. Simulações Monte Carlo de integrais de trajetória : propriedades elásticas do 4He sólido / Path integrals Monte Carlo simulations : elastic properties of 4He
The path-integral Monte Carlo (PIMC) method is a sophisticated approach for the simulation of many-body quantum systems. In particular, it has been extensively used for the study of manybody bosonic systems such as 4He. The main objective of the present dissertation is to apply the PIMC method to determine the elastic constants of solid 4He in its hcp phase.
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 30/11/2010
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5. Espectroscopia de alcalinos em Hélio líquido / Spectroscopy of Alkali in Liquid Helium
Alkali atoms are good probes for the understanding of liquid He properties. As such considerable experimental attention has been devoted to the analysis of the changes of line position and widths of the absorption spectra of alkali atoms in liquid He environment. On the theoretical side, several studies have used simplified models such as bubble and cluster
Publicado em: 2010
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6. Folatos, capacidade antioxidante e trans-2-nonenal em cerveja brasileira / Folate, antioxidant capacity and E-2-nonenal in Brazilian beer
In the present study methods were adapted and applied to quantify levels of folate, antioxidant capacity assessment and E-2-nonenal quantification in Brazilian beers. 5 brands of Pilsen, non-alcoholic and Malzbier beers were used, in can and amber bottle. For determination of folates (folic acid - FA, 10-methyl-folic acid - 10Methyl, 5-methyltetrahydrofolate
Publicado em: 2010
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7. Mathematical Modeling and Numeriacal Methods for Simulation of the Heat Conduction in Liquid Helium / Modelagem Matemática e Métodos Numéricos para Simulação da Condução do Calor no Hélio Líquido
The element helium, found mainly in natural gas reserves, condenses at temperature of 4.2K, and is the unique known substance that remains in liquid to absolute zero. In the liquid phase, the helium presents still another phase change in 2.19K, where passes of common liquid to superfluous liquid, with almost zero viscosity. These properties give the helium i
Publicado em: 2009
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8. Sistemas eletrônicos em duas dimensões : desordem e resposta dinâmica
In disordered systems the pinning strength on the carriers due to impurities or defects is one of the most important mechanisms that produce insulator behavior. A transition to a metal phase should occur if a driving field is applied to the system. In the last three decades, such transition in two-dimensional systems has attracted much attention in light of
Publicado em: 2009
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9. Filtro a base de nanofibras de carbono para sequestro de enxofre em efluentes gasosos ricos em H2S / Carbon nanofibers based filter to sulfur removal from efluents rich in H2S.
Over the last few decades, sulfur recovery from the H2S-containing acid gases have become more and more important due to the ever increasing standards of efficiency required by environmental protection measures. The general trend is to selectively transform H_2S into elemental sulfur which is a valuable product, by the modified Claus process. However, due to
Publicado em: 2009
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10. Determining plasma morphine levels using GC-MS after solid phase extraction to monitor drug levels in the postoperative period
OBJECTIVE: To implement a selective and sensitive analytical method to quantify morphine in small volumes of plasma by gas-liquid chromatography-mass spectrometry (GC-MS), aimed at post-operatively monitoring the drug. METHOD: A gas-liquid chromatographic method with mass detection has been developed to determine morphine concentration in plasma after solid
Clinics. Publicado em: 2008
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11. Two-dimensional Wigner crystal on helium films: an indication of quantum melting
Using molecular dynamics simulation (MD) we have investigated the melting of the two-dimensional Wigner crystal on 240Å-500Å liquid helium films supported by substrates of dielectric constants epsilons = 2.2-7.3. Our results show good agreement with available theoretical and experimental results for densities below 1.0×10(10)cm-2. For higher densities, we
Brazilian Journal of Physics. Publicado em: 2006-09
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12. Numerical simulation of N-vector spin models in a magnetic field
Three-dimensional N-vector spin models may define universality classes for such diverse phenomena as i) the superfluid transition in liquid helium (currently investigated in the micro-gravity environment of the Space Shuttle) and ii) the transition from hadronic matter to a quark-gluon plasma, studied in heavy-ion collisions at the laboratories of Brookhaven
Brazilian Journal of Physics. Publicado em: 2006-09