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71.
The results are reported of an MO-SCF-CNDO/2 study of the experimental and optimal geometries of the N4O62+ion cluster. The calculations are shown to support the stable existence of the N4O62+ complex and the suggestion of its discoverers [1] on the role of NO+ in the N2O4 solutions. The proposed interpretation of the bonding interaction explains why the shortest N β O distances are found with the NO+ ions which have their nitrogen atoms displaced out of the NO3? plane. 相似文献
72.
P. K. Manna P. K. Choudhury 《Journal of polymer science. Part A, Polymer chemistry》1972,10(7):2159-2167
Sodium amylopectin xanthate, prepared by xanthation of potato amylopectin in alkaline medium, was fractionated and the fractions in 1M NaOH were characterized by viscometry and light scattering. The expansion factor α was determined from the expression due to Orofino and Flory. The value of a of the Mark-Houwink relation, [η] = KMa, was also determined. Its weight-average molecular weight, end-to-end distance, branching, and other parameters in alkali solution were also evaluated. From the data, it was concluded that the sodium amylopectin xanthate molecule had a polydisperse random-coil chain configuration in 1M NaOH and had no tendency to aggregate in this medium. 相似文献
73.
A CNDO/2 calculation of ths total energy and electron distribution of propiolic acid and propynal shows that their dipole moment originates almost entirely from the charge distribution of the COOH and CHO groups and receives only a small contribution from the CCH group. These results provide a satisfactory explanation of very recent microwave dipole moment measurements on propiolic acid. 相似文献
74.
Semigroup Forum - In the endeavour of obtaining semigroup theoretic analogues i.e., the analogues of structure theorems of completely regular semigroups in the setting of additively regular... 相似文献
75.
Dario Duca Zsuzsanna Varga Gianfranco La Manna Tamás Vidóczy 《Theoretical chemistry accounts》2000,104(3-4):302-311
The hydrogenation mechanism of acetylene–ethylene mixtures on Pd catalysts under different experimental conditions was studied
by employing a time-dependent Monte Carlo approach set to use a fixed series of event probabilities. The dependence of the
catalyst activity and selectivity on the sizes of the metal particles was simulated at microscopic level and the results,
also refined by fitting procedures, suggested proper explanations for the apparent nonuniformity of the related experimental
findings. The use of the steric hindrance parameter of the surface species and the available surface energy on the metallic
catalyst sites was decisive for reproducing the experimental results.
Received: 16 September 1999 / Accepted: 3 February 2000 / Published online: 2 May 2000 相似文献
76.
Exchange bias and magnetic proximity effects are two novel phenomena that are in the limelight because of their fundamental and technological importance. Since both phenomena are interfacial in origin, we review these together. In the first part of this review, we have discussed the basics of these two phenomena. Subsequently, we have described numerous experimental examples involving a variety of composite magnetic materials and heterostructures. The recent theoretical models of these two interface phenomena have also been described. Finally, we have shed light on an obvious question: can one expect both these phenomena to occur together in any magnetically coupled system? We conclude that one can enhance the operating temperature of an exchange biased device by exploiting the magnetic proximity effect. 相似文献
77.
The title compound 1 has been synthesised through the intermediacy of the salt 5 obtained by acid hydrolysis of the obtically active β-carboline derivative 10,11-cyclohexylidene-12β-hydroxy-13β-(l-tetrahydro-β-carbolinyl)tetrahydrofuran (4). 相似文献
78.
79.
Propagation of SH‐wave in an initially stressed orthotropic medium sandwiched by a homogeneous and an inhomogeneous semi‐infinite media
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Santimoy Kundu Santanu Manna Shishir Gupta 《Mathematical Methods in the Applied Sciences》2015,38(9):1926-1936
The paper presents a study of propagation of shear wave (SH‐wave) in an orthotropic elastic medium under initial stress sandwiched by a homogeneous semi‐infinite medium and an inhomogeneous half‐space. The technique of separation of variables has been adopted to get the analytical solutions for the dispersion relation in a closed form. The propagation of SH‐waves is influenced by inhomogeneity parameters and initial stress parameter. Velocities of SH‐waves are calculated numerically for different cases. As a special case when the intermediate layer and half‐space are homogeneous, computed frequency equation coincides with general equation of Love wave. To study the effect of inhomogeneity parameters and initial stress parameter, we have plotted the velocity of SH‐wave in several figures and observed that the velocity of wave decreases with the increases of non‐dimensional wave number. It can be found that the phase velocity decreases with the increase of inhomogeneity parameters. We observed that the velocity of SH‐wave decreases with the increases of initial stress parameter in both homogeneous and inhomogeneous media. GUI has been developed by using MATLAB to generalize the effect of the parameters discussed. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
80.