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11.
《Journal of the European Ceramic Society》2005,25(6):857-862
Compressive creep tests in air were carried out on 1 cat.% Fe-doped alumina at a temperature T=1400 °C. Iron doping affected the plastic deformation by different ways in relation with Fe2+ cations population. Fe2+ cations sped up the deformation rates. FeAl2O4 spinel precipitates were identified and they were found (i) to interact with alumina grain boundaries (ii) to limit the grain growth within a range of strain. The Fe2+ cations underwent oxidation and this resulted in the dissolution of the some precipitates and in the decrease of deformation rates. It was suggested that deformation sped up this evolution through mass transport and that time was not a dominating parameter. 相似文献
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The use of quartz crystal microbalance (QCM) for on-line monitoring of the adsorption of low-density lipoprotein (LDL) onto cholesterol-modified dextran (CMD) was described. Kinetics studies were made and molecule interaction mechanism was discussed. Experimental results showed that kinetic curves fitted Langmuir adsorption equation quite well. When LDL concentrations (ng/μl) were 9.9, 12.38 and 14.14, respectively, the apparent rate constants (s− 1) and adsorption capacities (ng/cm2) were estimated to be 0.0477, 0.0536, 0.0628 and 124.5, 161.6, 194.3, respectively. The maximal LDL adsorption capacity attained 329.6 ng/cm2 and the adsorptive efficiency was calculated to be 72.91%. Moreover, a new method to evaluate the adsorption behavior was provided. 相似文献
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《Materials Letters》2006,60(25-26):3088-3090
In this paper, we doped p-type conductivity dehydrated nanotubed titanic acid (DNTA) into insulator polymer poly(methyl methacrylate) (PMMA). The electric properties of this nanocomposite were investigated. The photoluminescence efficiency of fluorescent dye 4-(dicyanomethylene)-2-t-butyl-6(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) in PMMA matrix was enhanced by doping with DNTA. Moreover, screen effect by DNTA with high permittivity caused the emission from DCJTB to be blue-shifted. 相似文献
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Ab initio method was employed to determine the mechanism of alkylation reaction of 2-butene with isobutane. The results indicated that 2-butene is rapidly protonated to form sec-butyl carbonium ion, which then reacts with isobutane to form tert-butyl carbonium ion. The resulting carbonium ion is then deprotonated to form isobutene that reacts rapidly with tert-butyl carbonium ion to form trimethylpentane (TMP) carbonium ion. Finally, the TMP+ carbonium ion is converted to TMP via the hydride transfer process. The transition states of the interactions were obtained by using the SCAN method (a calculation key word for potential energy surface) first and then the intrinsic reaction coordinates were traced using the Gaussian program. In addition, the energy changes and geometric parameters of the interactions were analyzed. The computed results indicated that the energy barriers are close to or less than zero for the interaction of isobutane with protonated 2-butene or for the interaction of tert-butyl carbonium ion with isobutene, suggesting rapid reaction steps of the carbonium ions. The 2,2,3-TMP is kinetically controlled, while the formation of 2,2,4-TMP is controlled by reaction equilibrium. The calculated results were in good agreement with the experimental results. 相似文献
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This article presents an optimization technique for the design of substrate‐integrated waveguide (SIW) filters using knowledge‐embedded space mapping. An effective coarse model is proposed to represent the SIW filter. The proposed coarse model can be analyzed in the available commercial software ADS. The embedded knowledge includes not only formulas but also extracted design curves, which help to build the mapping between the coarse and fine models. The effectiveness of the proposed method is demonstrated through a design example of a six‐pole SIW filter. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2012. 相似文献