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991.
Hydrochloric acid solutions (0.05–1.18m) containing p-nitroaniline (8×10–5M) as indicator base have H
o
values which increase with increase of ethylene carbonate (EC) content in the solvent mixture for a fixed molality of the acid. This behavior confirms similar results obtained in AN-H2O, MCS-H2O, DMSO-H2O and NMF-H2O systems. This trend indicates that the solvent basicity increases by successive addition of the organic solvent. The partition of the proton between water and EC has been calculated using Sadek's theory. It is clear that [H3O+] decreases gradually with increase of EC content. The change in the dissociation constant of p-nitroanilinium ion,
decreases sharply with increasing dielectric constant. The free energy change of transfer, G
t
o
, has been attributed to an electrostatic, G
t(el)
o
, and a nonelectrostatic, electrostatic, G
t(non)
o
component. It has been found that G
t(non)
o
is negative. 相似文献
992.
Yoshio Yuge 《Journal of statistical physics》1977,16(4):339-348
A site percolation approach to classical transport in disordered two-phase materials is presented. A Monte Carlo computer experiment gives the bulk conductivity of a 30 x 30 x 30 site simple cubic resistor network consisting of two kinds of unit resistor with different conductance. A modified effective-medium theory predicts very accurately the bulk conductivity of the network. This theory is found to agree well with available data for the thermal conductivity of real two-phase materials: glass particle-silicon rubber; glass fiber-plastics; air-saturated porous sandstone; and air-saturated fire brick. 相似文献
993.
Measurements relating to molar magnetic susceptibility, dc electrical conductivity and thermoelectric power of Nd, Sm, Eu
and Gd are reported. The ac electrical conductivity at a few temperature ranges is also given. It is found that it follows
the Curie-Weiss law behaviour and this has been attributed to the crystal field effect. The experimental value of Bohr magneton
for the magnetic ions has been found to be in good agreement with theory. Thermoelectric power is negative in the measured
temperature range suggesting these materials to bep-type semi-conductors and holes as the dominant charge carriers. The results are explained using band theory. 相似文献
994.
Denninger G Baldenhofer K Gessler R Binet L Gourier D 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2001,148(2):248-256
Electron nuclear magnetic double resonance on conduction electrons reveals the hyperfine interaction hidden by the fast electron spin exchange. We used the Overhauser shift technique to investigate the electron spin density of the conduction band of gallium oxide, beta-Ga(2)O(3). Due to the monoclinic structure, the conduction band of beta-Ga(2)O(3) is anisotropic and it is dominated by contributions from the two nonequivalent Ga sites. The large quadrupole couplings of the two gallium isotopes (69)Ga and (71)Ga (both with I = 3/2) are completely resolved in our double-resonance experiments. This resolved quadrupole interaction allows the determination of the electric field gradients at both gallium sites with high precision and high sensitivity. The resolved quadrupole splitting is the key to the site-selected determination of the hyperfine interaction. The concepts behind these double-resonance techniques are rather general and should be applicable in similar semiconductor systems. 相似文献
995.
Mingxin?QiuEmail author Toru?Mizunaml Terao?Shimomura Michitaka?Ohtaki 《Optical Review》2001,8(3):159-162
Generation of bulk second-order nonlinearity in silica glass requires higher poling temperature or longer poling time than that of near-surface second-order nonlinearity. The threshold conditions for initiating the bulk second-order nonlinearity are studied on Infrasil fused silica glass. The threshold poling time is strongly dependent on the poling temperature. The near-surface second-order nonlinearity is also studied, especially the dependence of thickness of the nonlinear layer on the poling temperature, poling voltage and poling time. Secondary-ion mass-spectroscopy measurement showed depletion of Na+ ions at the anodic surface. We assume there is an ionic wave during poling traveling from the anodic surface to generate the dipolar electric field that induces the near-surface second-order nonlinearity. 相似文献
996.
The reactions of acetophenone in water by pulsed corona discharges have been investigated to provide fundamental information concerning the reactions of acetophenone in water. Experimental results indicated that photolysis of acetophenone did not involve a hydroxyl radical mechanism and the majority flux of hydroxyl radicals originated from the dissociation of gas-phase oxygen in the plasma channels. The rate constants for photolysis and pyrolysis were determined to be 1.5×10–7 M-s–1, 2.2×10–4 s–1, respectively. The rate constant for the oxidative reactions was measured as 1.2×10–7 M-s–1. Results from this study support the proposal that acetophenone degradation reaction proceed through the oxidative reaction pathway, where molecular oxygen accelerates acetophenone degradation, photolysis, and pyrolysis pathways. 相似文献
997.
998.
999.
J.E. Barrios-Vargas 《哲学杂志》2013,93(29):3844-3857
The next-nearest neighbor interaction (NNN) is included in a tight-binding Kubo formula calculation of the electronic spectrum and conductivity of doped graphene. As a result, we observe a wide variation of the behavior of the conductivity, as happens in carbon nanotubes, since the Fermi energy and the resonance peak are not shifted by the same amount when the NNN interaction is included. This finding may have a profound effect on the idea of explaining the minimal conductivity of graphene as a consequence of impurities or defects. Finally, we also estimate the mean free path and relaxation time due to resonant impurity scattering. 相似文献
1000.
The present paper deals with the determination of quasi-static thermal stresses due to an instantaneous point heat source of strength gpi situated at certain circle along the radial direction of the circular plate and releasing its heat spontaneously at time t = τ. A circular plate is considered having arbitrary initial temperature and subjected to time dependent heat flux at the fixed circular boundary of r = b. The governing heat conduction equation is solved by using the integral transform method, and results are obtained in series form in terms of Bessel functions. The mathematical model has been constructed for copper material and the thermal stresses are discussed graphically. 相似文献