SO2-4/MxOy型固体超强酸催化剂的研究进展

概述了SO2-4/Mx Oy 型固体超强酸催化剂的分类、制备方法及表征手段,详细说明了通过促进剂、催化剂载体及引入金属或离子等对SO2-4/ZrO2型固体超强酸改性方面的研究进展,指出目前在SO2-4/Mx Oy 型固体超强酸催化剂研究方面存在的问题,展望了SO2-4/Mx Oy 型固体超强酸催化剂的发展前景。     

SO42-/MxOy型固体超强酸催化剂改性及应用研究进展

SO₄^2-/M_xO_y型固体超强酸型催化剂具有活性高、污染小、不腐蚀设备和可重复使用等优点,是一种典型的环境友好催化剂。分析微乳液法、水热法、回流老化法和模板法等制备方法对催化剂催化性能的影响,介绍催化剂载体改性、引入金属或分子筛、促进剂等改性方面的研究进展,综述SO₄^2-/M_xO_y型固体超强酸催化剂在有机反应包括异构化反应、酯化反应、烷基化反应、酰化反应、脱水反应和齐聚反应中的应用。今后研究重点是如何利用新技术改进催化剂的制备过程和提高固体酸比表面积。     

基于Flash Mx的《电力电子学》虚拟实验系统

采用Flash Mx开发的<电力电子学>虚拟实验系统具有电路动态仿真功能,以双极性正弦脉宽调制电路为例,定义变量、函数、MC的初始状态,据输入参数,计算电路工作模态间过渡时刻和电压电流波形点的位置参数,显示对应时刻的电压电流波形点和动态波形.利用Flash Mx开发相应的组件,编辑视图对象、编写程序.引用定义的数组实现电流流通路径显示.     

An Uncleaved Signal Peptide Directs the Malus xiaojinensis Iron Transporter Protein Mx IRT1 into the ER for the PM Secretory Pathway

Malus xiaojinensis iron-regulated transporter 1 (Mx IRT1) is a highly effective inducible iron transporter in the iron efficient plant Malus xiaojinensis. As a multi-pass integral plasma membrane (PM) protein, Mx IRT1 is predicted to consist of eight transmembrane domains, with a putative N-terminal signal peptide (SP) of 1–29 amino acids. To explore the role of the putative SP, constructs expressing Mx IRT1 (with an intact SP) and Mx DsIRT1 (with a deleted SP) were prepared for expression in Arabidopsis and in yeast. Mx IRT1 could rescue the iron-deficiency phenotype of an Arabidopsis irt1 mutant, and complement the iron-limited growth defect of the yeast mutant DEY 1453 (fet3fet4). Furthermore, fluorescence analysis indicated that a chimeric Mx IRT1-eGFP (enhanced Green Fluorescent Protein) construct was translocated into the ER (Endoplasmic reticulum) for the PM sorting pathway. In contrast, the SP-deleted Mx DsIRT1 could not rescue either of the mutant phenotypes, nor direct transport of the GFP signal into the ER. Interestingly, immunoblot analysis indicated that the SP was not cleaved from the mature protein following transport into the ER. Taken together, data presented here provides strong evidence that an uncleaved SP determines ER-targeting of Mx IRT1 during the initial sorting stage, thereby enabling the subsequent transport and integration of this protein into the PM for its crucial role in iron uptake.     

Numerical analysis of crystal growth of an InAs-GaAs binary semiconductor by the Travelling Liquidus-Zone method under microgravity conditions

We investigate the crystal growth process of an InAs-GaAs binary semiconductor by the Travelling Liquidus-Zone (TLZ) method numerically and discuss the possibility of growing a bulk In_0.3Ga_0.7As crystal. First, we explain this new crystal growth technique and then develop a numerical model and calculation method of the growth of binary crystals, by which the flow field in the solution, the temperature and concentration fields in both the solution and crystals, and the shape and movement of the crystal-solution interfaces are determined. We focus, in particular, on the effect of the solution zone width on the crystal growth process and the generation of supercooling in the solution in order to grow In_0.3Ga_0.7As. We find that a uniform In_0.3Ga_0.7As can be grown by the TLZ method under 1 μg conditions by adjusting the solution zone width and the temperature gradient in the solution at appropriate values, in which case buoyancy convection and supercooling induced in the solution are remarkably reduced.     

Statistical inference for equivalence trials with ordinal responses: A latent normal distribution approach

Testing of equivalence/non-inferiority has become an essential component in modern drug and treatment assessment. Before a newly developed treatment is introduced and applied to its target population, it is necessary to compare it to an existing (reference/standard) treatment. Unlike the traditional trial of testing the equality between two treatments, an equivalence trial, for instance, attempts to demonstrate that the responses to two treatments differ by an amount which is clinically insignificant. In many applications, the outcome measures of interest are usually recorded in ordinal scale (e.g., very good; good; moderate; poor). This paper presents a simple approach to the problem of equivalence testing in the presence of ordered categorical data. The proposed methodology operates on the assumption that the observed ordinal variable is governed by an underlying normally distributed trait. The new approach can be readily adopted for (i) commonly used equivalence limits such as difference and the ratio of treatment means and (ii) both one-sided non-inferiority and two-sided equivalence trials. We illustrate our methodology with two medical examples and demonstrate how test results and confidence interval estimates can be obtained from a freely available computer program.