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81.
82.
I. P. Kuranova K. M. Polyakov E. A. Smirnova W. E. Höhne V. S. Lamzin R. Meijer 《Crystallography Reports》2003,48(6):953-958
Crystals of Saccharomyces cerevisiae inorganic pyrophosphatase suitable for X-ray diffraction study were grown by cocrystallization of the enzyme with cobalt chloride and imidodiphosphate. Saccharomyces cerevisiae is a metal-dependent enzyme which catalyzes hydrolysis of inorganic pyrophosphate to orthophosphate. The three-dimensional structure of this enzyme was solved by the molecular-replacement method and refined at 1.8 Å resolution to an R factor of 19.5%. Cobalt and phosphate ions were revealed in the active centers of both identical subunits (A and B) of the pyrophosphatase molecule. In subunit B, a water molecule was found between two cobalt ions. It is believed that this water molecule acts as an attacking nucleophile in the enzymatic cleavage of the pyrophosphate bond. It was demonstrated that cobalt ions and a phosphate group occupy only part of the potential binding sites (two chemically identical and crystallographically independent subunits have different binding sites). The arrangement of ligands and the structure of the nucleophile-binding site are discussed in relation to the mechanism of action of the enzyme and the nature of the metal activator. 相似文献
83.
L. M. Vasilyak M. N. Vasil’ev S. P. Vetchinin D. N. Polyakov V. E. Fortov 《Journal of Experimental and Theoretical Physics》2003,96(3):440-443
The action of an electron beam on ordered dust structures in glow and low-pressure RF discharges was studied experimentally. The electron beam produces destruction and dynamic displacement of the dust structure. In the center of a dust structure, an electron beam with a low electron energy (tens of eV) at currents up to 1 mA caused structural disordering and “melting” in the region of its action but did not excite external crystal regions. Local action of an electron beam with a high electron energy (25 keV) and a beam current above 10 mA caused deformation of the whole dust structure and shifted it in the horizontal direction so that it was carried away from the RF discharge zone. The effect of dust structure displacements can be used to locally remove particles from a plasma. 相似文献
84.
85.
86.
87.
G. E. Volovik 《JETP Letters》1997,65(7):522-527
The efficiency of conversion of the heat flux into hard x radiation (HXR) is analyzed, via time-dependent two-temperature
one-dimensional non-LTE-radiation-hydrodynamic numerical modeling, for a heat-to-radiation flux converter linked to the edge
of a low-atomic-number hot Z-pinch. The domain of parameters in this scheme is found where about the same HXR yield can be
achieved at values of input energy which are an order of magnitude lower than in the conventional scheme of a radially imploding
plasma.
Pis’ma Zh. éksp. Teor. Fiz. 65, No. 7, 502–506 (10 April 1997)
Published in English in the original Russian Journal. Edited by Steve Torstveit. 相似文献
88.
89.
N. P. Venediktov M. Yu. Glyavin V. E. Zapevalov A. N. Kuftin A. S. Postnikova M. V. Yulpatova 《Radiophysics and Quantum Electronics》1997,40(4):336-342
A scheme for automated study of current-voltage characteristics of gyroresonance devices is developed. The effective emission
spread at the cathodes of powerful gyrotrons is studied by analysis of current-voltage characteristics. Experimental data
on the effective emission spread parameter for different modes are given. The permissible emission spread at the cathodes
of powerful gyrotrons is estimated, and the dependence of the electron beam parameters on the cathode emission spread is presented.
A complex measurement technique showing the contribution of different physical mechanisms to the cathode emission spread is
proposed.
Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia. Translated from Izvestiya Vysshikh Uchebnykh
Zavedenii, Radiofizika, Vol. 40, No. 4, pp. 506–516, April, 1997. 相似文献
90.
Processing-induced residual strains in solid cylinders of Nickel 200 were investigated using phase shifting moiré interferometry. Two different experimental approaches were used to study the strains produced during Tungsten-inert gas spot welding. A comparison of results for a ‘hot/fast’ and a ‘cool/slow’ weld demonstrate the capabilities of the general approach. Both experimental methods revealed distinct differences in the residual displacement and strain fields between the two types of welds. 相似文献