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941.
The energy levels of neutral anion (VA) and cation (VC) vacancies and antisite defects are calculated for the anion CA and cation AC sublattices of III–V semiconductors. An averaged energy level position for these defects is estimated to be Eav
abs = 4.9 eV. The position coincides with the local charge electroneutrality level. It is shown that the case, where the total
energies of formation of VA, VC and antisite CA, AC defects in the sublattices of binary semiconductors are similar, corresponds to the point-defect equilibrium condition and
stabilization of the Fermi level in the proximity of the local charge electroneutrality level.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 17–22, May, 2007. 相似文献
942.
943.
A technique for variation of the temperature factor of free-flight models by varying their initial temperature is described. An experiment on a ballistic range is carried out with a free-flying supersonic blunt cone with a half-angle of 15° at a Mach number of 2.3. The flow at the cone base is studied in the transition range (from the laminar to turbulent flow) of Reynolds numbers. The base flow pattern is determined from the shadowgraphs of the flow about the models. The drag coefficient of the blunt cone at a zero angle of attack is found by processing trajectory data. It is found that the near wake geometries and the drag coefficients of the models tested at the laboratory temperature and a temperature of 120 K differ. Explanations of this effect are given. 相似文献
944.
N. P. Kobelev 《Physics of the Solid State》2002,44(1):195-198
The relaxation contribution of the molecular reorientation in an elastic field of an acoustic wave to the effective shear moduli is calculated in the framework of the phenomenological two-level model of orientational states in the low-temperature phase of solid C60. The polarity of the rotation axis of C60 molecules and the possible existence of orientational domains in the structure of the low-temperature phase are taken into consideration. The estimates obtained are compared with the available experimental data. 相似文献
945.
Yozo Miura Hiroyuki Dote Hiroyuki Kubonishi Kenichi Fukuda Tomoko Saka 《Journal of polymer science. Part A, Polymer chemistry》2007,45(6):1159-1169
A dendritic macroinitiator having 16 TEMPO‐based alkoxyamines, Star‐16 , was prepared by the reaction of a dendritic macroinitiator having eight TEMPO‐based alkoxyamines, [G‐3]‐OH , with 4,4′‐bis(chlorocarbonyl)biphenyl. The nitroxide‐mediated radical polymerization (NMRP) of styrene (St) from Star‐16 gave 16‐arm star polymers with PDI of 1.19–1.47, and NMPR of 4‐vinylpyridine from the 16‐arm star polymer gave 16‐arm star diblock copolymers with PDI of 1.30–1.43. The ring‐opening polymerization of ε‐caprolactone from [G‐3]‐OH and the subsequent NMRP of St gave AB8 9‐miktoarm star copolymers with PDI of 1.30–1.38. The benzyl ether linkages of the 16‐arm star polymers and the AB8 9‐miktoarm star copolymers were cleaved by treating with Me3SiI, and the resultant poly(St) arms were investigated by size exclusion chromatography (SEC). The SEC results showed PDIs of 1.23–1.28 and 1.18–1.22 for the star polymers and miktoarm stars copolymers, respectively, showing that they have well‐controlled poly(St) arms. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1159–1169, 2007. 相似文献
946.
O. N. Filimonova 《Russian Journal of Applied Chemistry》2007,80(7):1213-1217
Influence of the process conditions on the production of “STAM” copolymer from waste products formed at join producing of styrene and propylene oxide, the acetophenone bottom residue at styrene rectification, with maleic acid. Effects of temperature, copolymerization process duration, weight ratio of acetophenone bottom residue to maleic acid and styrene content in the bottom residue are studied. 相似文献
947.
948.
A. Ray R. Sriravindrarajah J.-P. Guerbois P. S. Thomas S. Border H. N. Ray J. Haggman P. Joyce 《Journal of Thermal Analysis and Calorimetry》2007,88(1):279-283
The use of supplementary cementitious materials (SCM) is a well established practice worldwide in the manufacture of Portland cement (PC)-based construction materials. While utilisation of industrial by-products has been successful, the potential of mining wastes is yet to receive adequate attention in the context of construction materials. In an expanded form perlite, which is a naturally occurring, hydrated volcanic siliceous glass, is an ideal material as a lightweight aggregate for use in a wide range of construction materials including concrete. The mining and processing of the grades of perlite required for the production of lightweight aggregate results in the creation of a fine grained waste which currently has no economic value. This paper reports preliminary data on the utilisation of waste perlite fines as a SCM in calcium silicate-based construction material and discusses the potential of this mining waste to reduce the environmental impact of the production of conventional cement-based construction materials. 相似文献
949.
N-Acylalkylation of neutral and anionic N-nucleophiles with α-halocarbonyl compounds was investigated by quantum chemical methods
in terms of the density functional theory and by experimental methods for 2,3-dihydroimidazo[2,1-b]quinazolin-1(10)H-5-one, its N-anion, and simpler model structures. High reactivity of these reagents is determined primarily by stabilization
of transition states (TS) by bridge bonds involving halogen or nitrogen atoms rather than by conjugation, as has been commonly
accepted. Bridged TS are formed by both the substitution mechanism S
N
2 and the addition-elimination mechanism. α-Haloalkyl-substituted zwitterions, which are potential intermediates of stepwise
N-acylalkylation of neutral N-nucleophiles, do not exist in the isolated state, but they are rather efficiently stabilized
upon solvation. These zwitterions, as well as analogous O-anions generated from anionic N-nucleophiles, can serve as intermediates
of N-acylalkylation, as was demonstrated by localization of the corresponding TS.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1150–1164, June, 2007. 相似文献
950.
G. N. Kichigin 《Doklady Physics》2003,48(10):565-567