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101.
Abstract— Anabaena doliolum , when exposed to either ultraviolet-B (UVB) radiation or Pb, showed reduced growth rate, carbon fixation, O2 -evolution, photosynthetic electron transport activity and ATP pool size. The rate of respiration was found to increase in UVB-treated cells; this increase was more pronounced in the cells exposed to UVB and Pb simultaneously. The UVB-induced inhibition of 2,6-dichlorophenol indophenol (DCPIP) photoreduction and lowering of chlorophyll a fluorescence could not be reversed by artificial electron donors (diphenyl carbazide, NH2 OH and MnCl2 ). These electron donors, however, substantially reversed the inhibition caused by Pb, thereby suggesting that UVB primarily inhibits the photosys-tem II (PS II) reaction center and Pb arrests the electron flow at the water splitting site. Nevertheless, the suppressed fluorescence intensity and the reduced emission and excitation peaks of phycobilisomes indicate the involvement of Pb in inhibition of PS II. All combinations of UVB and Pb inhibited the different metabolic processes in a synergistic manner. 相似文献
102.
103.
Purple colored single crystals of the β-modification of Li3TiF6 have been prepared by heating an appropriate mixture of LiF and TiF3 at 820°C under an argon atmosphere. β-Li3TiF6 crystallizes in C2/c with a = 14.452(2) Å, b = 8.798(1) Å, c = 10.113(1) Å and β = 96.30(1)º. The structure is isotypic to β-Li3VF6 and contains isolated compressed TiF6 octahedra (dTi–F = 1.91–2.01 Å). Magnetic properties of β-Li3TiF6 were studied and discussed. Band structure calculations and calculations of the Madelung part of the lattice energy, MAPLE, were performed to discuss the chemical bonding. 相似文献
104.
Powder samples of the new oxide fluoride V2GeO4F2 have been obtained by the reaction of appropriate amounts V2O3, VF3, and GeO2 at 700°C for 18 h in an argon-filled sealed platinum tube. V2GeO4F2 crystallizes in the space group Pnma with a=9.336(1), b=8.898 (1), and c=4.912 (1) Å. The structure has been refined from X-ray powder diffraction data using the Rietveld method (Rint=5.5% and Rp=9.8%). The structure of V2GeO4F2 exhibits close packed layers of the anions with an ordering of O and F. The characteristic building units are discrete GeO4 tetrahedra with Ge-O distances of 1.75-1.80 Å. The V are coordinated by four O and two F to form VO4F2 octahedra connected via two common edges to give zigzag chains. These chains are linked via corners to form a three-dimensional network. The temperature dependence of the magnetic susceptibility of V2GeO4F2 indicates antiferromagnetic correlations. 相似文献
105.
106.
J. Tyagi 《Applied Mathematics Letters》2013,26(6):624-626
The purpose of this note is to show a generalization to Picone’s identity in a nonlinear framework. The classical Picone’s identity turns out to be a particular case of our result. We show, as an application of our results, that the Morse index of the zero solution to a semilinear elliptic boundary value problem is 0 and also establish a linear relationship between the components of the solution of a nonlinear elliptic system. 相似文献
107.
S. N. Achary O. D. Jayakumar S. J. Patwe A. B. Shinde P. S. R. Krishna S. K. Kulshreshtha A. K. Tyagi 《Pramana》2008,71(5):941-946
Herein we report the results of detailed crystallographic studies of Ca1−x
Ba
x
Zr4P6O24 compositions from combined Rietveld refinements of powder X-ray and neutron diffraction data. All the studied compositions
crystallize in rhombohedral lattice (space group R-3 No. 148). A continuous solid solution is concluded from the systematic
variation of unit cell parameters. The variation of unit cell parameters with the composition indicates decreasing trend in
a parameter with increasing Ba2+ concentration contrast to an increasing trend in c parameter.
相似文献
108.
Singh Gurjeet Singh P. J. Tyagi V. V. Barnwal P. Pandey A. K. 《Journal of Thermal Analysis and Calorimetry》2019,137(4):1381-1400
Journal of Thermal Analysis and Calorimetry - Cream is a milk derivative comparatively rich in fat, present in the form of emulsion of fat in skimmed milk, and acquired by physical extraction from... 相似文献
109.
110.
Intramolecular cyclopropanation of alkenes occurs thermally with iodonium ylides in the absence of conventional metal catalysts such as Rh(II) and Cu(II). In rigid molecular systems conversions are near quantitative. A mechanism is proposed involving formal 2+2 cycloaddition followed by reductive elimination of PhI to yield the cyclopropane. 相似文献