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171.
Srivastava Santosh Weissler G. L. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1973,1(4):17-22
The lowering of the ionization potentials of hydrogen and carbon atoms immersed in a high temperature and high density thermal plasma generated in a wall stabilized arc have been estimated from the advance or shift of their respective series limits in the vacuum ultraviolet region of the spectrum for different electron densities and temperatures. Results show a close agreement with those theoretical calculations in which the effects of both microfield and polarization terms are added. However, our electron densities are lower by about two orders of magnitude than the critical electron densities required by theory for the inclusion of the microfield term. The question of validity of a critical electrom density will be discussed. 相似文献
172.
173.
The band gaps of the polytypic crystals of lead iodide have been determined by studying the temperature variation of conductivity. Results obtained on several polytypic crystals show that the band gaps of the higher polytypes are lower than that of the parent 2H structure (2.56 eV). As for example the band gaps for 12H, 14H, 18H and 20H (disordered) were found to be 1.65, 1.44, 1.07 and 1.01 eV. The significance of the band gap determination in regard to the recent anomalous results on the physical properties of lead iodide crystals, has been indicated. 相似文献
174.
175.
R. S. Srivastava 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1980,31(2):297-303
Summary The motion of an incompressible viscous fluid in a curved pipe of elliptic cross-section is examined. The flux ratio in this pipe and in a straight pipe of elliptic cross-section has been evaluated under the same pressure conditions.
Zusammenfassung Die vorliegende Arbeit untersucht die Strömung einer inkompressiblen, zähen Flüssigkeit durch ein gekrümmtes Rohr mit elliptischem Querschnitt. Das Verhältnis des Durchflusses in diese Rohr und durch ein geradliniges Rohr von elliptischem Querschnitt unter demselben Druckgefälle wurde berechnet.相似文献
176.
K.S. Srivastava 《Journal of Electron Spectroscopy and Related Phenomena》1981,22(3):211-221
Using the theory of plasmon oscillations in solids, an alternative explanation is given for the line-like structure observed by Liefeld, Burr and Chamberlain [1] which moves with incident electron energy, resonates in intensity near the excitation energy of the Mα and Mβ lines, and leaves residual shoulders on the low-energy side of the lanthanum Mα and Mβ lines. 相似文献
177.
Eight mixed copper(II) complexes of the type [Cu(II)(D)(HL)], where D = anion of glycylglycine, glycyl-L-tyrosine or glycyl-L-phenylalanine, and HL = imidazole, 1-methylimidazole, 2-methylimidazole or benzimidazole have been prepared and characterised. The visible and EPR spectral studies of these complexes indicate that they are monomeric having five coordinate square pyramidal geometry (possibly distorted) about Cu(II). The dipeptide behaves as terdentate ligand in these complexes with amino, ionised amide nitrogen and carboxylate oxygen donor atoms approximately tetragonally disposed about Cu(II). The magnetic and bonding parameters obtained by detailed EPR spectral analysis coupled with electronic absorption spectral data suggest that imidazole, 1-methylimidazole, 2-methylimidazole or benzimidazole occupies the fourth position in the tetragonal plane and water molecule occupies an axial position about Cu(II) in solid state and in solution. 相似文献
178.
L.?FeligioniEmail author O.?Panella Y. N.?Srivastava A.?Widom 《The European Physical Journal B - Condensed Matter and Complex Systems》2005,48(2):233-242
An investigation of two-time correlation functions is reported
within the framework of (i) stochastic quantum mechanics and (ii)
conventional Heisenberg-Schr?dinger quantum mechanics. The
spectral functions associated with the two-time electric dipole moment
correlation functions are worked out in detail for the case of the
hydrogen atom. While the single time averages are identical for
stochastic and conventional quantum mechanics, differences arise in
the two approaches for multiple time correlation functions. 相似文献
179.
S.?SaxenaEmail author R.?Srivastava 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2004,30(1):23-35
We have carried out distorted wave calculations for electron impact 5
2P, 6 2S and 4 2D excitations of rubidium atom at incident electron energies in the range of 10-200 eV. Results are presented for differential and total cross-sections of these excitations, Stokes parameters of the excitation of the fine-structure resolved and unresolved 5 2P and 4 2D states, complete experiment parameters for the excitation of 5 2P state and the STU spin parameters of its fine structure states. Good agreement is found on comparison of our results with the available experimental data and the earlier theoretical calculations. Except for the resonance 5
2P transition no earlier calculations were reported for the excitation of the higher 6 2S and 4 2D states.Received: 25 February 2004, Published online: 22 June 2004PACS:
34.80.Dp Atomic excitation and ionization by electron impact - 34.80.Nz Spin dependence of cross-sections; polarized electron beam experiments 相似文献
180.
Embryogenic tissues of Dioscorea bulbifera were cryopreserved using the encapsulation-dehydration technique. Genetic stability of plants regenerated from cryopreserved embryogenic tissues was assessed using molecular, biochemical and morphological analysis. The random amplified polymorphic DNA (RAPD) analysis of 60 cryopreserved-derived and 20 in vitro grown (control) plantlets showed that 10 primers produced 62 clear reproducible DNA fragment profiles. The amplification products were monomorphic for all the plantlets except one. A total of 4960 DNA fragments were obtained from this study showing no variation in RAPD profiles. The diosgenin content of cryopreserved-derived plants, analyzed using HPLC, was similar to that of control plants. Morphology and the ability to form microtuber were also found to be unaltered in cryopreserved embryo-derived plantlets. Thus, the D. bulbifera plants regenerated from cryopreserved embryogenic tissues were genetically stable at the molecular, biochemical and morphological levels. 相似文献