Results 301 to 310 of about 313,034 (335)
Some of the next articles are maybe not open access.
Acta Radiologica, 1998
Purpose: To evaluate histological changes and duration of enhancement after the intra-arterial injection of helium gas microbubbles in comparison with conventionally used carbon dioxide (CO2) microbubbles at US Material and Methods: Four different doses of helium gas microbubbles (0, 0.1, 0.2 and 0.5 ml/kg) mixed with normal saline and own blood were
T. Nishiharu +5 more
openaire +3 more sources
Purpose: To evaluate histological changes and duration of enhancement after the intra-arterial injection of helium gas microbubbles in comparison with conventionally used carbon dioxide (CO2) microbubbles at US Material and Methods: Four different doses of helium gas microbubbles (0, 0.1, 0.2 and 0.5 ml/kg) mixed with normal saline and own blood were
T. Nishiharu +5 more
openaire +3 more sources
Solid State Phenomena, 2006
Gas quenching in vacuum furnaces is an increasingly attractive option because it has a low environmental impact and the least distortion of parts being treated. Whilst nitrogen is by far the most common quenching gas, helium is a viable option where higher cooling rates are required, particularly for carburised components.
Paul Stratton +2 more
openaire +1 more source
Gas quenching in vacuum furnaces is an increasingly attractive option because it has a low environmental impact and the least distortion of parts being treated. Whilst nitrogen is by far the most common quenching gas, helium is a viable option where higher cooling rates are required, particularly for carburised components.
Paul Stratton +2 more
openaire +1 more source
Polarizability of Helium and Gas Metrology
Physical Review Letters, 2007Using a quasispherical, microwave cavity resonator, we measured the refractive index of helium to deduce its molar polarizability A(epsilon) in the limit of zero density. We obtained (A(epsilon,meas) - A(epsilon,theory))/A(epsilon) = (-1.8 +/- 9.1) x 10(-6), where the standard uncertainty (9.1 ppm) is a factor of 3.3 smaller than that of the best ...
J. W. SCHMIDT +3 more
openaire +2 more sources
Transitions to turbulence in helium gas
Physical Review A, 1987Experimental study in gaseous helium at low temperature (4 K) of thermal convection up to a Rayleigh number $R={10}^{11}$. Three regimes are observed, a chaotic state up to $R=2.5\ifmmode\times\else\texttimes\fi{}{10}^{5}$, a soft-turbulence state up to $R=4\ifmmode\times\else\texttimes\fi{}{10}^{7}$, and then a hard-turbulence state.
, Heslot, , Castaing, , Libchaber
openaire +2 more sources
Turbulence in helium-gas free convection
Physical Review A, 1989Results on a Rayleigh-B\'enard experiment in helium gas at 5 K in a cylindrical cell of aspect ratio 1 are presented. The Rayleigh number spans a range from ${10}^{5}$ to ${10}^{12}$. A large-scale coherent flow is observed via the correlation of two adjacent temperature probes.
, Sano, , Wu, , Libchaber
openaire +2 more sources
Diffusion of hydrogen atoms in helium gas and helium atoms in hydrogen gas
Physical Review A, 2002The potential of Meyer and Frommhold describing the interaction between hydrogen and helium atoms is used to calculate the diffusion coefficients of hydrogen atoms in helium gas and helium atoms in hydrogen gas as functions of temperature, taking into account higher-order corrections of transport theory.
H-K. Chung, A. Dalgarno
openaire +1 more source
Turbulent convection in helium gas
Physica D: Nonlinear Phenomena, 1992Abstract Various changes in measured signals were observed in thermal convective experiments of low-temperature helium gas, indicating that there are more than one turbulent states in the system. The more recently observed transition occurs at a Rayleigh number of about 1011, within the hard turbulence regime.
Emily S.C. Ching +3 more
openaire +1 more source
1970
Only small users of liquid helium — or those blessed with more money than they know what to do with — can afford to let helium out into the atmosphere. Where liquid helium is bought out, it is a matter of returning the helium gas in cylinders to the supplier.
openaire +1 more source
Only small users of liquid helium — or those blessed with more money than they know what to do with — can afford to let helium out into the atmosphere. Where liquid helium is bought out, it is a matter of returning the helium gas in cylinders to the supplier.
openaire +1 more source
Oxygen and helium gas mixtures for dyspnoea
Current Opinion in Supportive & Palliative Care, 2007Recent reports of the benefits of helium/oxygen gas mixtures (heliox) use for the relief of dyspnoea and exercise limitation have stimulated interest in the use of heliox in the palliation of dyspnoea especially in chronic obstructive pulmonary disease patients.
Elizabeth A, Laude, Sam H, Ahmedzai
openaire +2 more sources
Electron Transport in Helium-Rare-Gas Mixtures
Physical Review Letters, 1994New calculations of electron transport in helium-rare-gas mixtures are presented. It is shown that the elastic collisions with helium in helium Ramsauer rare gas mixtures play analogous roles to weak inelastic collisions in molecular gas Ramsauer rare gas mixtures.
, Nagpal, , Garscadden
openaire +2 more sources