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991.
Barrett formula has been obtained in the framework of the effective field approach by including the zero-point energy. By fitting with experimental data of dielectric constant of SrTiO3, we find that they agree in the whole temperature range fairly well if the zero-point energy is assumed to change from a small value at low temperature to a large value at high temperature. 相似文献
992.
Saqib Ali Syed Usman Ahmad Sadiq‐ur‐Rehman Saira Shahzadi Masood Parvez Muhammad Mazhar 《应用有机金属化学》2005,19(1):200-200
A trigonal bipyramidal C2ClS2 coordination geometry for tin is found in Ph2Sn(S2CN(CH2)5)Cl. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
993.
An aspiration based simulated annealing algorithm for continuousvariables has been proposed. The new algorithm is similar to the one givenby Dekkers and Aarts (1991) except that a kind of memory is introduced intothe procedure with a self-regulatory mechanism. The algorithm has beenapplied to a set of standard global optimization problems and a number ofmore difficult, complex, practical problems and its performance comparedwith that of the algorithm of Dekkers and Aarts (1991). The new algorithmappears to offer a useful alternative to some of the currently availablestochastic algorithms for global optimization. 相似文献
994.
S. R. Mishra G. J. Long F. Grandjean R. P. Hermann S. Roy N. Ali A. Viano 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,24(1-3):93-96
The structural and magnetic properties of the granular
iron nitride-alumina composite materials,
(FexN)0.2(Al2O3)0.8
and
(FexN)0.6(Al2O3)0.4,
fabricated using high-energy ball milling have been determined
by using X-ray diffraction, Mössbauer spectroscopy, and
magnetization measurements. The Mössbauer spectra, fit with a
distribution of hyperfine fields between zero and 40 T, indicate
that the weighted average field decreases with increasing
milling time. The isomer shift increases with milling time
because of a reduced iron 4s-electron density at the grain
boundaries. Coercive fields as high as 325 and 110 Oe are
obtained for
(FexN)0.2(Al2O3)0.8
at 5 and 300 K, respectively; the increase in the coercive field
upon cooling indicates the presence of superparamagnetic
particles. The coercive field increases with milling time
because of the reduced particle size. The decrease in the
magnetization results from the increase in both the
superparamagnetic fraction and the concentration of surface
defects with increased milling time. 相似文献
995.
Azeeza Ali Ismaeel 《Semigroup Forum》1992,45(1):283-287
For an inverse semigroupS with its idempotents dually well-ordered, we prove thatS is isomorphic to the semigroup of all one-to-one partial right translations ofS. Also, we prove for a Bruck semigroupS=B(T, α) thatS isE-unitary if and only ifT isE-unitary and α is an idempotent pure homomorphism. Moreover, we characterize allE-unitary covers ofB(T, α), whereT is a finite chain of groups. 相似文献
996.
M. Ali R. Watts W.J. Karl M.R.J. Gibbs 《Journal of magnetism and magnetic materials》1998,190(3):1667
Magnetostrictive FeSiBC amorphous thin films based on the METGLAS® 2605SC composition have been produced by RF magnetron sputtering. The magnetic properties were investigated using the magneto-optical Kerr effect, with both point hysteresis measurements and domain imaging. Significant in-plane anisotropy is observed in the as-grown samples, which was attributed to the residual field from the magnetron sputter source. The effects of various treatments on the samples were investigated, including the use of forming fields, stress, and thermal processing. The deliberate introduction of stress into these materials is found to allow excellent control of both the direction and magnitude of magnetic anisotropy, and can also be used as a novel method for the absolute measurement of magnetostriction. The treatments are evaluated for their potential to control anisotropy in magnetostrictive device applications. 相似文献
997.
The effect of heat treatment on the Fe2+/Fe3+ ratio in some alkali phosphate glasses containing antimony and iron oxides has been investigated. Differential thermal analysis, Mossbauer spectroscopy, magnetic susceptibility and density measurements as well as the molar volume calculations were used in this study. The obtained data indicate that all glasses show approximately unchangeable stability. It is found, from the area under the Mossbauer absorption spectra that ferrous transformed gradually to ferric ions and the transformation rate constant was found to be 48 min−1. The elapsed time was found to be 160 min. This transformation represents a first-order solid state reaction. The molar magnetic susceptibility measurements confirm the above results. 相似文献
998.
The purpose of this study was to examine the efficiency with which rice bran (treated or untreated) removes heavy metals, especially Cr(III) and Hg(II), from acidic solution. Sorption assays were done in shaken flasks in the presence of rice bran. Different experimental conditions such as pH, volume of solution, bran weight, particle size, exchange time and stirring time were improved. The efficiency of bran was studied before and after treatments. For treatment, solutions of acid, alkali and salt were used. The results show that after treating with 4 M sodium chloride solution, its efficiency in removal of Cr(III) and Hg(II) was improved. Kinetic measurements of chromium and mercury removal by bran have revealed that sorption equilibrium was obtained after 10 min of contact. Sorption experiments done with various granulometric fractions of rice bran have shown that this sorbent has the same efficiencies in meshes higher than 20. Further research is necessary in order to determine a mechanism for cations removal by the bran. It is mentioned that the process of making polished rice from brown rice discharges rice bran; therefore, it is very inexpensive, with a cost of 1/50 ? 1/40 of that of synthetic sorbent, and thus its use would significantly lower the cost of wastewater treatment. 相似文献
999.
1000.
A new homologous series of thermotropic polyesters has been synthesized by polycondensation reaction between isophthaloyl chloride and mesogenic diols 4,4′-bis(ω-hydroxyalkoxy)biphenyl in which the spacer length is varied from 3 to 6 methylene units. The thermal behavior of the polymers has been characterized using polarized light microscopy and differential scanning calorimetry (DSC). The odd members exhibit a smectic C (SC) phase in a narrow temperature interval, while the even members form a smectic A (SA) phase in a broader temperature range. All of the obtained compounds were characterized by conventional spectroscopic methods. 相似文献