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11.
Study of EPR, optical properties and electrical conductivity of vanadyl doped Bi2O3.PbO.B2O3 glasses
Gahlot PS Agarwal A Seth VP Sanghi S Gupta SK Arora M 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,61(6):1189-1194
Heavy metal based oxide glasses having composition xBi(2)O(3).(0.30 - x)PbO.0.70B(2)O(3) have been prepared (0.00 < or = x < or = 0.15, mol%) containing 2.0mol% of V(2)O(5) by normal melt-quenching technique. Electron paramagnetic resonance (EPR), optical spectra and dc conductivity of these glasses have been studied. Spin Hamiltonian parameters (SHP) of VO(2+) ions, dipolar hyperfine parameter, P and Fermi contact interaction parameter, K, molecular orbital coefficients (alpha(2) and gamma(2)) and optical band gap have been calculated. It is observed that in these glasses, the tetragonal nature of V(4+)O(6) complex increases with Bi(2)O(3) content. Increase in Bi(2)O(3):PbO ratio results in the contraction of 3d(xy) orbit of the unpaired electron in the vanadium ion, and the SHP are dependent on the theoretical optical basicity, Lambda(th). In present glasses, the conductivity (activation energy) first decreases (increases) with increase in mol% of Bi(2)O(3) content upto x = 0.08 and then shows a maxima (minima) at x = 0.10 and then starts decreasing (increasing) upto x < or = 0.15 with mol% of Bi(2)O(3) content. 相似文献
12.
B.R. Arora R.K. Banerjee T.S.R.Prasad Rao N.K. Mandal N.C. Ganguli S.P. Sen 《Thermochimica Acta》1973,7(1):25-40
Kinetics of decomposition of the precipitates of the ZnO&2sbndAl2O3 system, prepared by coprecipitation and mechanical mixing of the individual precipitates, have been studied. The decomposition of zinc basic carbonate is a first order rate process with an activation energy of 34.5 kcal/mole (Coats and Redfern equation). The decomposition of aluminium hydroxide is also best described as a first order rate process with one break in the Coats and Redfern plot corresponding to activation energies of 29.4 and 8.3 kcal/mole respectively. The entire course of decomposition of coprecipitated as well as mechanically mixed samples cannot be described by any one of the many rate equations available. Consequently, the Coats and Redfern equation has been employed. The plots indicate one or two breaks and thus two to three values of activation energy are reported. From the results it is to be concluded that decomposition of these precipitates is a heterogeneous process. The first step is definitely the decomposition of zinc basic carbonate followed by decomposition of aluminium hydroxide and/or interaction of the two precipitates resulting in the formation of “precursor” to spinel. The results of our earlier investigation on the same system (especially the formation of precursors) are well supported by the results reported in this investigation. p]A new equation (a modified form of the Elovich equation) has been proposed for such heterogeneous decomposition processes. The proposed equation also appears to be the general form of the equations where diffusion is the rate controlling process. 相似文献
13.
Heats of mixing aniline, o-toluidine, and N,N-dimethyl aniline with chloroform have been determined by an adiabatic calorimeter. The results have been examined for molecular interactions between them, and they indicate that aniline and o-toluidine are associated through hydrogen bonds. Enthalpy of bond formation in a 1:1 complex has also been determined. 相似文献
14.
Nonpeptidic foldamers capable of displaying protein-like functionality were prepared by swapping amide bonds with 1,2,3-triazole rings. The overall conformation of these triazole oligomers is largely dictated by dipole-dipole interactions between adjacent rings. Solution NMR studies suggest that a zigzag conformation, which closely mimics the beta-strand structure, predominates in two different tetramers. 相似文献
15.
Kartar S. Arora C. G. Overberger 《Journal of polymer science. Part A, Polymer chemistry》1986,24(1):37-60
The synthesis of carbazola substituted N-acylated polyethylenimines, namely, poly[N-(9-carbazolyl)acetylethylenimine] 20 and poly[N-(2-(9-carbazolyl))propanoylethylenimine] 21 by a grafting reaction onto PEI and isomerization polymerization of the carbazole substituted 2-oxazolines is reported. A complete acylation of amino groups in PEI by the 9-carbazolylacetyl groups was achieved by the p-nitrophenyl active ester method but PEI was only partially N-acylated by the 2-(9-carbazolyl)propanoyl groups under similar reaction conditions. The carbazole substituted 2-oxazolines, namely, 2-(9-carbazolyl)methyl-2-oxazoline 18 and (R,S)-2-[1-(9-carbazolyl)]ethyl-2-oxazoline 19 , were prepared by a base induced cyclization of ß-chloroamides. The ring-opening isomerization polymerization of 18 and 19 in the molten state with a cationic initiator (dimethyl sulfate, methyl triflate, or ethylene glycol ditosylate) gave 20 and 21. Gel permeation chromatography of 20 and 21 obtained with different monomerto-initiator ratios gave evidence of a chain transfer reaction with the monomer. The polymers were characterized by elemental analyses, IR, and 1H-NMR spectroscopy. 相似文献
16.
Lal Sohan Arora Sanjiv Kumar Vinod Rani Shikha Sharma Chetan Kumar Parvin 《Journal of Thermal Analysis and Calorimetry》2018,132(3):1707-1716
Journal of Thermal Analysis and Calorimetry - The synthesis of Schiff bases of chitosan is performed by the reaction of chitosan with different heteroaryl aldehydes, i.e., furfuraldehyde,... 相似文献
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19.
We present a seventh order iterative method for solving systems of nonlinear equations. The algorithm is derivative free per full iteration. A comparison between the computational efficiencies of proposed technique and existing techniques of similar nature is made. It is shown that for large system the new method is more efficient. The performance is tested through numerical experimentation which also confirms the theoretical results. 相似文献
20.
Anurag Shukla Urvashi Arora N. Sukavanam 《Journal of Applied Mathematics and Computing》2015,49(1-2):513-527
This paper deals with the approximate controllability of retarded semilinear stochastic system with nonlocal conditions in Hilbert Spaces under the assumption that the corresponding linear system is approximately controllable. The control function for this system is suitably constructed by using the infinite dimensional controllability operator. With this control function, the sufficient conditions for the approximate controllability of the proposed problem in Hilbert Space are established. The results are obtained by using Banach fixed point theorem. Finally, two examples are provided to illustrate the application of the obtained results. 相似文献