铁(Ⅲ)—苯芴酮—聚乙二醇辛基苯基醚显色反应的研究及应用

详细研究了非离子表面活性剂聚乙二醇辛基苯基醚（OP）存在下铁（Ⅲ）与苯芴酮的显色反应。结果表明铁（Ⅲ）与苯芴酮形成了蓝紫色的配合物，其最大吸收波长λmax为614nm，对比度（△λ）为74nm，摩尔吸光系数ε614为6．41×104L·emol(-1)·cm(-1)，铁量在0～16μg／25mL范围内服从比耳定律。所拟方法用于磷矿样中铁的分析与邻菲罗啉法结果一致。     

Electron Emission from Barium Strontium Titanate Ceramics

This paper focuses on understanding the influence of materials' properties on the ferroelectric electron emission. Ferroelectric ( x =1.0 and 0.8) and paraelectric ( x =0.67 and 0.5) compositions of barium strontium titanate (Ba _x Sr_{(1− x )}TiO₃) system were chosen for study based on their different ferroelectric and dielectric properties. Similar emission current waveforms were obtained from four compositions with negative triggering voltage applied to the rear electrode of the samples. It was difficult to explain the experimental results using the spontaneous polarization-switching model. The mechanism of electron emission from Ba _x Sr_{(1− x )}TiO₃ ceramics was ascertained to surface plasma emission.     

Analysis of the oscillatory behavior of double-walled carbon nanotube-based oscillators

Molecular dynamics simulations of oscillatory behaviors of double-walled carbon nanotube-based oscillators are performed. The second-generation empirical bond-order potential is used for the atomic interactions within a wall, and a registry-dependent and four different registry-independent van der Waals potentials are used for the atomic interactions between walls. It is found that the frequencies of the nanotube oscillators are sensitive to the choice of the van der Waals potentials. An almost non-decay oscillation is observed for the registry-dependent potential when there is no rocking motion. However, an apparent decay oscillation is observed when rocking motion occurs. A decay oscillation is observed for all registry-independent potentials even without rocking motion. Mechanisms leading to unstable oscillatory behavior are analyzed.     

环己烷液相无催化剂的氧化动力学研究

采用搅拌釜反应器,在确认已排除传质因素对反应速率影响的情况下,研究了环己烷液相无催化剂的氧化反应动力学。应用自由基理论及最优化计算技术,从导出的8个候选动力学模型中,确定了最佳的动力学模型,它能满意地描述环已烷氧化过程。该动力学可为环己烷氧化工业生产操作条件的优化、反应器的选型及工业设计提供依据。     

结晶性高聚物作为相变材料的应用

本文研究了结晶性高聚物聚乙烯及其共混物作为相变材料对模拟发热体铜片热量的吸收作用，由于相变的吸热，铜片的温度在一定时间范围内保持在一个定值。选择不同的相变材料，可使这种温度平台出现在不同的温度范围，不共晶的共混物可有两个以上的温度平台，提高了降温效果。     

Synthesis,characterization, and thermal properties of phosphorus‐containing,wholly aromatic thermotropic copolyesters

A series of phosphorus‐containing, wholly aromatic thermotropic copolyesters from acetylated 2‐(6‐oxide‐6H‐dibenz〈c,e〉〈1,2〉oxa phosphorin‐6‐yl)‐1,4‐dihydroxy phenylene, p‐acetoxybenzoic acid, terephthalic acid, and isophthalic acid were prepared by melting polycondensation. The structure and basic properties of the polymers, such as the glass‐transition temperature (T_g), melting temperature (T_m), thermal stability, crystallinity, and liquid crystallinity, were investigated with Fourier transform infrared, elemental analysis, differential scanning calorimetry (DSC), thermogravimetric analysis, wide‐angle X‐ray diffraction, and hot‐stage polarizing optical microscopy. The copolyesters had relatively high T_g values ranging from 183 to 192°C. The T_m values obtained from DSC curves for samples P‐20 and P‐25 were 290 and 287°C, respectively (where the number in the sample name indicates the molar fraction of the phosphorus‐containing monomer in the reactants). The initial flow temperatures of other samples observed with hot‐stage polarizing microscopy were 271–290°C. The 5% degradation temperatures in nitrogen ranged from 431 to 462°C, and the char yields at 640°C were 41–52%. All the copolyesters, except P‐40, were thermotropic and nematic. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1278–1284, 2002     

大学毕业生就业中的几对矛盾及其化解

我国大学毕业生就业形势日趋严峻,就业问题已经引起了社会的广泛关注,社会各界都在为大学生就业出主意、想办法.笔者对目前毕业生就业中的几对矛盾及其化解作了一些探索,本文就如何解决这些矛盾谈一点看法.     

原子吸收光谱法测定生产金刚石电解触媒废液沉渣中的锰

通过正交实验确定了利用原子吸收分光光度法测定锰的最佳测试条件,并测定了生产金刚石电解触媒废液沉渣中的锰含量,实验准确度和精密度较高,适合工业快速分析.     

种子法制备聚合物乳液技术的进展

从建筑乳液的生产现状、自生种子法与外加种子法的区别、种子乳液的特点及外加种子法生产的乳液特性等方面介绍了种子法制备乳液技术的进展。