用三元共聚改性剂制PVC耐热管材

利用自行研制的三元共聚耐热改性剂与聚氯乙烯（PVC）共混制成耐热管材专用料，考察了共混体系中耐热改性剂、抗冲改性剂、填料及热稳定剂等各组分对材料拉伸强度、冲击强度和维卡软化点等综合性能的影响，同时对氯化聚氯乙烯和自制耐药改性剂的耐药和加工性能进行了比较，所研制的耐热改性剂与PVC混合后耐热效果较好，且易挤出加工。研制的耐热管材的维卡软化点可达100℃，比无规聚丙烯管材的维卡耐热性能要高。     

Phase evolution and thermophysical properties of high-entropy RE2(Y0.2Yb0.2Nb0.2Ta0.2Ce0.2)2O7 oxides

Pursuing novel thermal barrier–coating materials with lower thermal conductivity and high-temperature stability can simultaneously improve the working efficiency and service temperature of a gas turbine. In this study, a series of high-entropy RE₂(Y_0.2Yb_0.2Nb_0.2Ta_0.2Ce_0.2)₂O₇ (RE = La, Nd, Sm, Gd, Dy, and Er) oxides were prepared though solid-state reaction. Through tuning the rare-earth cations, an order–disorder transition occurs from certain partially ordered weberite structure (C222₁) to disordered defective fluorite structure (Fm$\overline{3}$m). All the high-entropy RE₂(Y_0.2Yb_0.2Nb_0.2Ta_0.2Ce_0.2)₂O₇ oxides possess low thermal conductivity in the range of 0.91–1.34 W m⁻¹ K⁻¹ at room temperature, which can be attributed to increased lattice anharmonicity and disorder, resulting in additional phonon scattering. Herein, we proved that the incorporation of heterovalent cations at B-sites in high-entropy A₂B₂O₇ crystals is an effective strategy to reduce the thermal conductivity without compromising the decrease of oxygen vacancy. Moreover, the high-entropy RE₂(Y_0.2Yb_0.2Nb_0.2Ta_0.2Ce_0.2)₂O₇ oxides show the relatively higher thermal expansion coefficients of 10.3–10.7 × 10⁻⁶°C⁻¹ and excellent phase stability at elevated temperatures.     

控制紫外波长合成维生素D3的研究

在合成维生素D3的过程中有多种光异构化产物．光异构产物取决于激发的紫外波长。束用一步光异构法。加入两种滤光液窄化禹压汞灯紫外波长在270hm-320hm．授维生素D3的转化率达到67％。     

泡沫塑料加工过程中的气泡成核理论(Ⅱ)——剪切能成核理论及其发展

介绍了剪切流场中泡沫塑料加工的气泡成核理论,分析评述了剪切流场中泡核拉伸模型、空穴成核模型对气泡成核机理的解释及存在的不足;对静态熔体中气泡成核过程进行了能量描述;介绍了最新的气泡成核中的剪切能成核理论,该理论较完善地解释了剪切流场中气泡成核过程;最后指出了气泡成核理论研究的发展方向。     

新显色剂2，6－二溴－4－乙氧基偶氮胂直接吸光光度法测定微量铋

新显色剂２，６－二溴－４－乙氧基偶氮肿在１．５ｍｏｌ·Ｌ－１ＨＣｌＯ４介质中，与Ｂｉ（Ⅲ）生成稳定的深色络合物，最大吸收波长为６３９ｕｍ，摩尔吸光系数为９．６７×１０４Ｌ·ｍｏｌ－１·ｃｍ－１，灵敏度高，常见离子允许量大。Ｂｉ（Ⅲ）在０～２５μｇ／２５ｍＬ范围内符合比耳定律。以试样空白为参比，直接吸光光度法测定铜及铜合金中的铋，方法简便，结果令人满意。     

溶胶-凝胶法制备的钛酸钡铁电微晶玻璃的显微结构与介电特性

通过对钛酸钡铁电微晶玻璃的体系选择和成分设计，利用溶胶-凝胶法合成了具有纯钛酸钡结晶相的微晶玻璃。研究了合成过程中凝胶结构变化和析晶行为。结果表明：纯钛酸钡铁电晶体可以在BaO-TiO2-Al2O3-SiO2凝胶中通过调整热处理条件而控制析晶，钛酸钡晶体的析晶活化能为657 kJ／mol。通过控制玻璃体中钛酸钡晶粒的尺寸，利用Raman光谱研究了其铁电本征尺寸效应。结果表明：钛酸钡晶体在玻璃体中的铁电临界尺寸为19nm。     

A Truncated Sum of Processing‐Times–Based Learning Model for a Two‐Machine Flowshop Scheduling Problem

Scheduling with learning effects has gained increasing attention in recent years. A well‐known learning model is called “sum‐of‐processing‐times‐based learning” in which the actual processing time of a job is a nonincreasing function of the jobs already processed. However, the actual processing time of a given job drops to zero precipitously when the normal job processing times are large. Moreover, the concept of learning process is relatively unexplored in a flowshop environment. Motivated by these observations, this article addresses a two‐machine flowshop problem with a truncated learning effect. The objective is to find an optimal schedule to minimize the total completion time. First, a branch‐and‐bound algorithm incorporating with a dominance property and four lower bounds is developed to derive the optimal solution. Then three simulated annealing algorithms are also proposed for near‐optimal solution. The experimental results indicated that the branch‐and‐bound algorithm can solve instances up to 18 jobs, and the proposed simulated annealing algorithm performs well in item of CPU time and error percentage. © 2011 Wiley Periodicals, Inc.     

碳化物陶瓷的研究现状及发展趋势

本文综述了现阶段碳化物陶瓷超细粉末的主要制备工艺以及烧结方法,同时指出了碳化物陶瓷今后的发展趋势。     

脱硫石膏粉煤灰胶结材水化硬化机理及耐水性研究

以火电厂的两种废渣即脱硫石膏和粉煤灰为主要原料制得的胶结材，其强度明显高于普通石膏制品，软化系数大于０．８５。采用水化热测定、ＸＲＤ和ｐＨ值测定及ＳＥＭ／ＥＤＸＡ分析，并结合宏观试验结果，分析了这种胶结材的水化硬化机理和微结构特点，并对其耐水性提高的原因进行了讨论。     

Hydrogen evolution in alkaline solution on electrolytic nickel-cobalt and nickel-iron deposited with different bath compositions and current densities

Nickel-cobalt and nickel-iron electrodeposits were characterized as hydrogen electrodes in alkaline water electrolysis (6 mol/L KOH, 25°C). The nickel-based codeposits were fabricated with different bath compositions and at different current densities. The hydrogen evolution in water electrolysis on the nickel-based codeposits was apparently enhanced as compared with that on nickel. The improvement of the electrocatalytic behaviour of the hydrogen electrodes is attributed to their composition and an increase of their active surface, which are dependent on the electrodeposition conditions.