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The expansions of plasma in neon plus helium under a modulated high voltage pulse regime has been studied. Photomultiplier studies of the striated appearance show that the bright regions are developed in sequence. 相似文献
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Abstract A pseudo-potential technique has been applied to calculate the annihilation rates for positrons in bubbles of helium gas in gold and silver. The positron pseudo-wavefunction in each case was found to be in a surface state of the metal, the exact form of which displayed a slight dependance on the density of the helium gas. The annihilation rate of the positron was the sum of a nearly constant surface rate and a strongly density dependant annihilation rate with the helium electrons. There is a trend for annihilation with the helium to be greater in metals with low free electron densities, the helium in such metals resting closer to the metal surface thus increasing the overlap of the positron wavefunction with the helium. 相似文献
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PC. M. Gubbens G. J. Boender A. M. van der Kraan K. H. J. Buschow 《Hyperfine Interactions》1992,68(1-4):329-332
DyFe12?xMx (M=Si,Ti,Cr) were studied with57Fe and161Dy Mössbauer spectroscopy. The deduced coupling constants JRFe of these compounds are about equal. It is found that Si is substituting one particular Fe-site, while Cr is substituting Fe randomly. In DyFe10Si2 two Fe-sites favour a c-axis anisotropy, while the third one favours the basal plane. 相似文献
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The gamma spectrum from Cobalt 60 decay has been investigated with a 40 cc Ge(Li) detector. A peak at 822 keV is shown to be not a gamma transition but a single escape peak and an upper limit of 10 is given to the branching ratio of the 2158 keV level. 相似文献
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Proteggente AR Basu-Modak S Kuhnle G Gordon MJ Youdim K Tyrrell R Rice-Evans CA 《Photochemistry and photobiology》2003,78(3):256-261
There is considerable interest in the biological properties of flavonoids in terms of their antioxidant and cytoprotective actions. The interaction of the flavanone hesperetin with human skin fibroblasts (FEK4) has revealed the potential for metabolism to hesperetin glucuronide and its subsequent extrusion. As a consequence of this observation, the effectiveness of hesperetin glucuronides, in comparison with that of the aglycone form, in protecting against UV-A radiation has been investigated. The results indicate that hesperetin glucuronides, but not hesperetin, protect against UV-A-induced necrotic cell death. 相似文献
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MR Eskildsen AB Abrahamsen PL Gammel DJ Bishop NH Andersen K Mortensen PC Canfield 《Pramana》2002,58(5-6):903-905
We compare the results of small angle neutron scattering on the flux line lattice (FLL) obtained in the borocarbide superconductor
LuNi2B2C with the applied field along the c- and a-axes. For H‖c the temperature dependence of the FLL structural phase transition from square to hexagonal symmetry was investigated. Above
10 K the transition onset field. H
2(T), rises sharply, bending away from H
c2(T) in contradiction to theoretical predictions of the two merging. For H‖a a first order FLL reorientation transition is observed at H
tr=3–3.5 kOe. Below H
tr the FLL nearest neighbor direction is parallel to the b-axis, and above H
tr to the c-axis. This transition cannot be explained using nonlocal corrections to the London model. 相似文献
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The Doppler-broadening of the positron annihilation line in 5N indium has been studied over the temperature range 77 K to 427 K. No evidence for self-trapping has been discovered; rather, the prevacancy rise in the F-parameter appears linear. The best value for EV is 0.59±0.03 eV. 相似文献