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981.
982.
Unusual behavior of nuclear relaxation in CeCu2Si2 “possible evidence for triplet superconductivity”
Yoshio Kitaoka Koh-ichi Ueda Takao Kohara Kunisuke Asayama 《Solid State Communications》1984,51(7):461-466
Nuclear relaxation of 63Cu in the superconducting state of the Kondo-lattice system CeCu2Si2 has been studied with the use of the 63Cu nuclear quadrupole resonance technique under zero field and down to 65mK. The nuclear spin-lattice relaxation rate (1/T1) decreases drastically just below Tc=0.67 K down to 0.5Tc without the apparent enchanced behavior and then is found to be almost temperature independent below 0.3Tc. These results suggest that the superconductivity in CeCu2Si2 is not in the usual BCS regime. The analysis based upon the existing triplet pairing model with an anisotropic energy gap describes well the behavior from Tc down to 0.5Tc, while the temperature independence below 0.3Tc remains unexplained. 相似文献
983.
984.
985.
An attractive Bose-Einstein condensate with a vortex splits into two pieces via the quadrupole dynamical instability, which arises at a weaker strength of interaction than the monopole and the dipole instabilities. The split pieces subsequently unite to restore the original vortex or collapse. 相似文献
986.
We investigate the possibility of geometrical electrophoresis, which is based on nanofabrication techniques. (GEE) utilizes geometrical effects during electrophoresis, which are generated by physical interactions between walls and a macromolecule confined in spaces smaller than the Flory radius. When a polymer is injected into a small space, confinement energy is usually required. However, the confinement energy form depends on the geometry of the space. In the case of electrophoresis, the electric field itself changes depending on the geometry. Using a nanofabricated quartz chip with a curved channel, we investigated electrophoretic behavior of high molecular weight DNA based on the curvature effect. 相似文献
987.
Zhang YJ Tanaka T Betsumiya Y Kusano R Matsuo A Ueda T Kouno I 《Chemical & pharmaceutical bulletin》2002,50(2):258-262
The association of 10 different tannins and related polyphenols with gramicidin S, a cyclic peptide having a rigid beta-turn structure, has been examined using 1H-NMR spectroscopy. In the presence of pentagalloylglucose and epigallocatechin-3-O-gallate, the proton signals due to proline and the adjacent phenylalanine moieties selectively shifted to up field, suggesting a regioselective association with the beta-turn structure. The association was also supported by the observation of intermolecular nuclear Overhauser effects between epigallocatechin-3-O-gallate and the peptide. In contrast, ellagitannins, biogenetically derived from pentagalloylglucose, showed small and non-selective chemical shift changes, suggesting that interaction with these tannins is relatively weak. The hydrophobicity of the tannin molecules and the steric hindrance of the interaction site are thought to be important in the association. 相似文献
988.
A reliable and efficient procedure for constructing five- to eight-membered oxacycles has been developed. Allenes with both a phosphoryl group and a suitable delta-hydroxyalkyl side chain at the C1-position underwent an endo mode ring-closing reaction to give five- to seven-membered oxacycles. Changing the phosphoryl group to a phosphono functionality facilitated the preparation of eight-membered congeners. Introduction of a cis double bond to the alkyl side chain of the starting allenes made possible the easy formation of medium-sized oxacycles, such as the dihydrooxocin and tetrahydrooxonin frameworks, regardless of the electron-withdrawing group (POPh2, PO(OEt)2, SOPh, and SO2Ph) at the C1-position. 相似文献
989.
990.