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Natural frequencies of a two layered elastic ring, on equi-spaced, identical radial supports, are obtained by using a wave approach. Two types of support conditions are investigated. With the outer layer viscoelastic, the theory of forced damped normal modes is used to obtain the resonant frequencies and the modal loss factors of the structure. Results presented show the effect of the thickness ratio on the resonant frequency and the modal loss factor. The effect of rotational constraints at the supports is also reported. 相似文献
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The syntheses of several saturated, pyrene-containing, metal-chelating lipids are described. These lipids are capable of strongly binding to transition metal ions employing the metal-chelating headgroup. The excimer-to-monomer ratio of the pyrene groups changes with addition of cupric ions to the liposomes. Three other transition metal ions (Zn(2+), Ni(2+), and Hg(2+)) did not cause any appreciable changes in the excimer-to-monomer ratio. [reaction--see text] 相似文献
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Priya Budhani Sayed Aftab Iqbal Suman Malik Mamta Bhattacharya Liviu Mitu 《Journal of Saudi Chemical Society》2010,14(3):281-285
The present paper deals with the synthesis and characterization of Schiff base complexes of pyrazinamide an antitubercular drug. Metals selected for complexation are copper, silver, gold, zinc, mercury, iron and cobalt. The complexes have been suitably synthesized and isolated in pure powdered form. Analytical data agrees with the compositions M(L), M′(L)2 and M″(L)2·2H2O, respectively where M = Ag, M′ = Cu, Au, Zn and Hg and M″ = Fe and Co, ligand metal ratios were also confirmed by monovariation method and Job’s method of continuous variation. Molar conductance values suggest the non ionic nature of the complexes. The tentative structure assigned to the complexes on the basis of stoichiometry and analytical data were further supported by spectral studies viz; IR, NMR, magnetic susceptibility and electronic spectra. A preliminary attempt has also been made to compare the potencies of metal complexes with parent drug. The Cu and Ag complexes are giving encouraging results. Particle size studies further suggest that the drug molecule undergoes reduction in size on complexation. 相似文献
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Sabyasachi Ghosh S. Mallik Sourav Sarkar 《The European Physical Journal C - Particles and Fields》2010,70(1-2):251-262
We analyse the structure of one-loop self-energy graphs for the ρ meson in real time formulation of finite temperature field theory. We find the discontinuities of these graphs across the unitary and the Landau cuts. These contributions are identified with different sources of medium modification discussed in the literature. We also calculate numerically the imaginary and the real parts of the self-energies and construct the spectral function of the ρ meson, which are compared with an earlier determination. A significant contribution arises from the unitary cut of the π ω loop, that was ignored so far in the literature. 相似文献
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A new chromone-substituted dihydrotriflavonol, (2S,3S)[6-{(3S) 3″,5″-dihydroxy-6″-methoxydihydrochromone}5,3′,4′,5′-tetrahydroxy-7-methoxy-3-O-8-dihydroflavone]2 3-O-8[6-{(3S) 3″,5″-dihydroxy-6″methoxydihydrochromone}3,5,3′,4′,5′-pentahydroxy-7-methoxydihydroflavonol] was isolated from the leaves
of Anogeissus pendula. The structure was determined by UV, 1H NMR, 13C NMR, HMBC, and CD data. 相似文献