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A. Kriaa M. Hajji F. Jamoussi A. H. Hamzaoui 《Surface Engineering and Applied Electrochemistry》2014,50(1):84-94
The A.C. impedance plots were used as tools to analyze the electrical response of two varieties of Tunisian halloysite 1: 1 and illitic samples 2: 1 as a function of frequency at different temperatures (80–800°C). The real and imaginary parts of the complex impedance trace semicircles in the complex plane. Except for the illite, It-1, the second sample analyzed in this study, these plots give evidence for the presence of both bulk and grain boundary effect, above 600°C onwards. The bulk resistance of the materials decreases with the rise in temperature. Impedance Spectroscopy data reveal a non-Debye type of dielectric relaxation. The Nyquist plots show the negative temperature coefficient of resistance of both pure Tunisian illite and halloysite samples. The results of bulk electrical conductivity and its activation energy are presented for the two mineral clay samples. For illite It-1, the activation energy values estimated from the AC conductivity pattern and modulus pattern are very similar and suggest a possibility of a long-range mobility of charge carriers (ions) via hopping mechanism of electrical transport processes at higher temperature. On the other hand, for the halloysite sample provided from kasserine, (Ha-Kass), the modulus analysis admit that the electrical transport processes of the material are very likely of electronic nature. Relaxation frequencies follow an Arrhenius behavior with the activation energy values not comparable to those found for the electrical conductivity. 相似文献
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H. Okamoto 《Journal of Phase Equilibria and Diffusion》1992,13(3):325-326
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《Acta Materialia》2007,55(17):5917-5923
Extended stacking faults, with lengths of up to 10 nm, that join {1 1 1}/{1 1 2} twin-boundary junctions were observed by high-resolution transmission electron microscopy (HRTEM) in gold thin films. Circuit analysis shows that these defects possess a Burgers vector of 1/3〈1 1 1〉. In order to explain the generation of these extended defects, we consider the behavior of 1/3〈1 1 1〉 dislocations at {1 1 1}- and {1 1 2}-type twin boundaries and near {1 1 1}/{1 1 2} twin-boundary junctions using HRTEM observations and theoretical modeling. By establishing the interaction forces that lead to this defect configuration, our analysis shows that the relief of intrinsic strain at the junction corners, which results from the incompatibility of the translation states at the intersecting boundaries, is sufficient to stabilize the stacking fault extension. Because grain–boundary junctions possess intrinsic strain fields whenever they join boundaries with incompatible translation states, similar mechanisms for stacking fault emission may arise between other closely spaced grain–boundary junctions. 相似文献
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The ternary alloys of the rare earths with lead and palladium were studied for the stoichiometric ratios 1:1:1 and 1:1:2 with respect to the structure of these alloys and their existence field. RPbPd (R = La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Y, Ho, Er, Tm, Yb) compounds have a hexagonal structure, hP9 Fe2P type, while RPbPd2 (R = Pr, Sm, Gd, Tb, Dy, Ho, Er, Yb) alloys have the cubic AlCu2Mn-type structure (cF16, BiF3 superstructure). 相似文献
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《腐蚀工程科学与技术》2013,48(1):34-46
AbstractOxidation tests in CO2 atmospheres on nominally identical casts of low alloy steels have revealed wide variation in oxidation resistance. A study has been made of the influence of chemical composition, mechanical and thermal treatment, and remelting on the CO2 oxidation behaviour of steels of the 21/4 Cr 1 Mo and 1 Cr 1/2 Mo type.Statistical analyses of CO2 oxidation results have shown a strong positive correlation of oxidation rate with sulphur content in certain instances, but a number of anomalies have been found. A similar relationship has been obtained between ‘MnS’ content and oxidation rate by area count studies of the inclusions in a range of 2 1/4 Cr 1 Mo steels. These have also indicated a possible effect of ‘MnS’ particle size and particle size distribution which could account for some of the anomalous results obtained in the statistical work. Conventional solid state heat treatments appear to have no significant effect on the oxidation behaviour of 2 1/2 Cr 1 Mo and while remelting in argon did not generally improve oxidation behaviour, remelting in vacuo followed by forging and rolling resulted in a material of high oxidation resistance. 相似文献
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人体存在多种类型的药物转运体,对于药物的吸收、分布和排泄起重要作用。参与药物跨膜转运的转运体功能受影响,将可能导致诸多临床药物的疗效、毒副作用甚至药物相互作用的发生。在各种影响因素中,遗传多态性所起的作用最为重要,可导致基因表达和蛋白功能发生改变。目前,阐明转运体基因的多态性以及基因型与表型之间的相互关系已成为应用遗传信息指导临床个体化用药的必要步骤。本文就肝脏有机阴离子转运多肽1B1(OATP1B1[OATP-C],编码基因SLCO1B1)基因多态性对药代动力学和药效动力学的影响及其临床意义等方面的进展作一综述。 相似文献