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981.
Stanisław Urban Joanna Czub Roman Dąbrowski Albert Würflinger 《Phase Transitions》2013,86(4-5):331-342
Differential thermal analysis (DTA) method was applied to study the pressure–temperature phase diagrams for four members of the 4′-alkyl-4-isothiocyanato-biphenyl (nBT) homologous series (n?=?9–12). These compounds exhibit a smectic E polymorphism enriched by a smectic A phase for two longest members. Measurements were performed in the temperature range 25–110°C and the pressure range up to 165?MPa. For all substances studied the pressure-induced phases were established with one or two triple points in the examined pressure range. In addition, for the 11BT and the 12BT the phases existing under atmospheric pressure disappeared under relatively low pressures. The results are compared with recently studied smectogenic n-alkyl-cyanobiphenyl (nCB) compounds. 相似文献
982.
Fusheng Liu Weiqin Ao Laicai Pan Qibao Wang Jialing Yan Junqin Li 《Phase Transitions》2013,86(6):585-597
The isothermal section of the Lu–Fe–Ga ternary system at 773?K was investigated and constructed based on X-ray powder diffraction analysis. Thirteen binary compounds, Lu2Fe17, Lu6Fe23, LuFe2, LuGa3, LuGa2, Lu3Ga5, LuGa, Lu3Ga2, Lu5Ga3, Fe3Ga, Fe6Ga5, Fe3Ga4, FeGa3, nine ternary solid solutions, T1-LuFe2–1.43Ga0–0.57, T2-LuFe1.34–0.92Ga0.68–1.08, T3-LuFe0.52–0.26Ga1.48–1.74, T5-LuFe2.04–1.72Ga0.96–1.28, T6-Lu6Fe23–21.4Ga0–1.6, T7-Lu2Fe17–14.5Ga0–3.5, T8-Lu2Fe12.9–8.1Ga4.1–8.9, T9-LuFe6.8–5.5Ga5.2–6.5, T10-LuFe5.2–4.5Ga6.8–7.5, and two ternary compounds, T4-LuFe2.35Ga0.65 and T11-Lu2FeGa8 have been confirmed. The structures of the five new ternary compounds or solid solution T2, T3, T4, T5 and T8 are determined by Rietveld refinement method. 相似文献
983.
We study the dynamics of a coupled two-channel ASEP in which intra-channel transition rates are dependent on the configuration of neighboring channel. The binding constant k, which signifies the ratio of inter-channel transition rates, is introduced and the symmetric and asymmetric coupling conditions are analyzed for different values of k. The vertical cluster mean-field theory is used to study the system behavior exactly in strong coupling conditions and approximately in intermediate coupling conditions. Additionally, the consequences of particular dynamics such as totally asymmetric simple exclusion process (TASEP), partially asymmetric simple exclusion process (PASEP) and symmetric simple exclusion process (SSEP) in either one or both channels are investigated. It is found that the transition rates have a significant influence on both the qualitative and quantitative nature of the phase diagrams. The mathematical computation shows how the number of phases varies from 3 via 6 to 7 under different environments. Interestingly, in the fully asymmetric coupling case, the results are found to be independent of the magnitude of non-zero vertical transition rate. Our theoretical arguments are in well agreement with extensively performed Monte-Carlo simulation results. 相似文献
984.
Abstract Optical measurements in the diamond anvil cell (DAC) as well as thermodynamics, show cubic GaAs I to be unstable at 300 K, at 13 GPa. The thermodynamic phase line from GaAs I to the high pressure (H.P.) form(s) is at 11 ± 2 GPa. Large hyteresis makes the actual I→II transition observable only at 17.5 ± 1 GPa. 相似文献
985.
Janusz Jurczak 《高压研究》2013,33(2):99-113
Abstract Some important problems of organic synthesis and ways to solve them by the use of hgh pressure are the topic of this paper. Three representative groups of organic reactions, cycloadditions, simple additions, and nucleophilic and electrophilic substitutions, illustrate the possibilities and usefulness of the high-pressure technique in organic synthesis. Moreover, applications of high-pressure methodology to syntheses of natural products are described. Examples are given of the influence of pressure on organic reactions in the following essential aspects: acceleration of the reaction rate, modification of regio-and stereochemistry, and changes in the reaction equilibrium. 相似文献
986.
D. Makow 《Molecular Crystals and Liquid Crystals》2013,570(1):347-353
Polysiloxanes with suitable side-chains form a cholesteric liquid crystal phase that can be applied to a substrate to produce a durable coating which exhibits strong colours below the glass transition temperature. The peak reflectance is almost 0.5 and a nearly 1.0 peak reflectance can be obtained using a half-wave retardation plate coated on both sides with the material and viewed from one direction against a black background. Values below 0.5 and between 0.5 and 1.0 have been also obtained using suitable solvents and alignment techniques. Many desired spectral reflectance distributions can be then obtained because of the additive color properties of such cholesteric coatings. As a result it is possible to produce a larger colour gamut than with real surface colours such as pigments and dyes. Employing commercially available material experimental work was carried out demonstrating a greatly expanded colour gamut on the chro-maticity diagram. Also it is possible to modify the spectral reflectance distribution of coloured substrates by coating them with a material having a reflectance peak at the desired band of wavelength. 相似文献
987.
PCILO conformational calculations have been carried out on several model compounds of thermotropic liquid crystalline polyesters [- OC-R1 -CO-O-R2]- where R1 = biphenyl, terphenyl and R2 = (-CH2-)3, -CH2-C(CH3)2-CH2–CH2-C(C2H5-) CH2-. The calculated structures can be compared to the X-ray crystallographic data. The conformational characteristics of the carboxyl groups are independent of the number of phenyl rings. The introduction of substituents into the flexible spacer results in a sharpening of the potential energy wells and an increase in the energy barriers. 相似文献
988.
989.
990.
根据Voronoi胞的几何性质,获得了积分点的二阶Voronoi胞顶点的表达式,并对各邻近结点相关的顶点进行排序以使其生成的二阶Voronoi胞切割面为凸多边形,从而获得各切割凸多边形面域的面积表达式;最后,基于复合函数链式求导法则,获得了三维自然单元法non-Sibson插值形函数导数的显式格式。相比Lasserre算法,该方法具有直观、便于编程且计算量小的特点。悬臂梁的算例结果进一步说明了该方法的可靠性,证实了文献[2,7,8]关于自然单元法具有比有限元中常应变单元更高的精度,理论上和双线性单元的精度同阶的结论。 相似文献