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61.
L. V. El’nikova 《Journal of Superconductivity and Novel Magnetism》2007,20(2):197-199
We describe the lyotropic liquid crystalline phase transitions in the lipid mixture dipalmitoil-PC/dilauroy-PC/cholesterol
by 3D spin-1 lattice model. The formation of nanoscale domains with the characteristic size about 300 nm was studied in experiments
on confocal fluorescence microscopy (CFM) (G. V. Feigenson and J. T. Buboltz, Biophys. J.
80, 2775 (2001)). The structure parameters of the lamellar vesicle in dipalmitoil-PC-rich phase, corresponding to these regions,
are verified by numerical Monte Carlo simulations on the lattice. We point its superconductivity analogy properties at the
region of phase stability for composition-dependent nanoscopic region. 相似文献
62.
采用SE 3 0为固定液进行色谱柱分离 ,用外标定量法测定泥土中的微量六氯环戊二烯 ,结果最小检知量为 0 .18× 10 - 6 ,相关系数为 0 .99992。 相似文献
63.
TiSiW12O40/TiO2催化合成丙酸正丙酯 总被引:2,自引:0,他引:2
研究了固载杂多酸盐TiSiW12O40/TiO2催化丙酸与正丙醇的酯化反应,探讨了催化剂用量,反应时间及醇酸摩尔比对酯收率的影响。当醇酸摩尔比为1.3:1,催化剂的量为醇酸总质量的1.5%。反应时间为1.0h,酯产率可达71.4%以上,采用该催化剂合成丙酸正丙酯不仅酯化反应温度低,反应时间较短,催化剂用量少,而且可较好地回收利用,可降低成本;因此,TiSiW12O40/TiO2是合成丙酸正丙酯的优良催化剂,具有良好的应用前景。 相似文献
64.
J.-P. Croisille 《Computing》2006,78(4):329-353
We introduce a new box-scheme, called ``hermitian box-scheme' on the model of the one-dimensional Poisson problem. The scheme
combines features of the box-scheme of Keller, [20], [13], with the hermitian approximation of the gradient on a compact stencil,
which is characteristic of compact schemes, [9], [21]. The resulting scheme is proved to be 4th order accurate for the primitive
unknown u and its gradient p. The proved convergence rate is 1.5 for (u,p) in the discrete L
2 norm. The connection with a non standard mixed finite element method is given. Finally, numerical results are displayed on
pertinent 1-D elliptic problems with high contrasts in the ellipticity, showing in practice convergence rates ranging from
1 to 2.5 in the discrete H
1 norm.
This work has been performed with the support of the GDR MOMAS, (ANDRA, CEA, EDF, BRGM and CNRS): Modélisation pour le stockage des déchets radioactifs. The author thanks especially A. Bourgeat for his encouragements and his interest in this work. 相似文献
65.
通过适当的工艺措施,采用Bridgman法生长了直径为30mm的X射线及γ射线探测器级的Cd.9Zn0.1Te晶锭.测试结果表明:该晶锭结晶质量良好,位错密度低,成分均匀,杂质含量低,红外透过率和电阻率都十分接近本征Cd.9Zn0.1Te的值.并从晶体的生长特性、缺陷和杂质的角度,分析了生长高性能晶体的条件,研究了生长Cdl-xZnxTe晶体的x值与缺陷和杂质浓度之间的关系. 相似文献
66.
A ternary blend system comprising poly(cyclohexyl methacrylate) (PCHMA), poly(α‐methyl styrene) (PαMS) and poly(4‐methyl styrene) (P4MS) was investigated by thermal analysis, optical and scanning electron microscopy. Ternary phase behaviour was compared with the behaviour for the three constituent binary pairs. This study showed that the ternary blends of PCHMA/PαMS/P4MS in most compositions were miscible, with an apparent glass transition temperature (Tg) and distinct cloud‐point transitions, which were located at lower temperatures than their binary counterparts. However, in a closed‐loop range of compositions roughly near the centre of the triangular phase diagram, some ternary blends displayed phase separation with heterogeneity domains of about 1 µm. Therefore, it is properly concluded that ternary PCHMA/PαMS/P4M is partially miscible with a small closed‐loop immisciblity range, even though all the constituent binary pairs are fully miscible. Thermodynamic backgrounds leading to decreased miscibility and greater heterogeneity in a ternary polymer system in comparison with the binary counterparts are discussed. © 2003 Society of Chemical Industry 相似文献
67.
Five new salts based on 1-alkyl-2-methyl pyrrolinium ion are reported, two involving the iodide ion and three involving the bis(trifluoromethanesulfonyl) amide ion. The iodide salts have melting points around 100 °C, while the amide salts have melting points around room temperature. Two of the amide salts can be easily quenched into the glassy state and exhibit glass transition temperatures around −70 °C. The 2-methyl pyrrolinium cation bears structural similarities to the aromatic imidazolium cations on one hand and the cyclic ammonium cation family based on the pyrrolidinium cation on the other. The properties of the salts reported here are compared within these two related families of salts. 相似文献
68.
K. Y. Cheah T. S. Tang Fujio Mizukami Shu-ichi Niwa Makoto Toba Y. M. Choo 《Journal of the American Oil Chemists' Society》1992,69(5):410-416
A new catalyst, ruthenium-tin-alumina is found to selectively hydrogenate oleic acid to 9-octadecen-1-ol (oleyl + elaidyl
alcohol) at low pressure with high yield. Catalyst preparation methods, catalyst raw materials and activation conditions have
a significant effect on the activity of the catalyst. The optimum atomic ratio of ruthenium to tin is about 1:2. Catalyst
prepared by an improved sol-gel method shows higher activity and selectivity than catalysts prepared by impregnation and coprecipitation
methods. Chloride is found to have a negative effect on catalytic activity. The best catalyst is prepared from chloride-free
ruthenium and tin raw materials. Under the optimum reaction conditions of 250°C and 5.6 MPa, the selectivities for 9-octadecen-1-ol
and total alcohol (9-octadecen-1-ol + stearyl alcohol) formation are 80.9% and 97%, respectively, at a conversion of 81.3%. 相似文献
69.
Numerical Modeling of Silicon Photodiodes for High-Accuracy Applications Part I. Simulation Programs
Jon Geist Deane Chandler-Horowitz A. M. Robinson C. R. James 《Journal of research of the National Institute of Standards and Technology》1991,96(4):463-469
The suitability of the semiconductor-device modeling program PC-1D for high-accuracy simulation of silicon photodiodes is discussed. A set of user interface programs optimized to support high-accuracy batch-mode operation of PC-1D for modeling the internal quantum efficiency of photodiodes is also described. The optimization includes correction for the dark current under reverse- and forward-bias conditions before calculating the quantum efficiency, and easy access to the highest numerical accuracy available from PC-1D, neither of which is conveniently available with PC-1D’s standard user interface. 相似文献
70.
J Strother Moore 《Formal Aspects of Computing》1994,6(1):60-91
We present a formal model of asynchronous communication between two digital hardware devices. The model takes the form of a function in the Boyer-Moore logic. The function transforms the signal stream generated by one processor into that consumed by an independently clocked processor, given the phases and rates of the two clocks and the communications delay. The model can be used quantitatively to derive concrete performance bounds on communications at ISO protocol level 1 (physical level). We use the model to show that an 18-bit/cell biphase mark protocol reliably sends messages of arbitrary length between two processors provided the ratio of the clock rates is within 5% of unity. 相似文献