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。     

The role of crystallization kinetics in the development of the structure and properties of polypropylene filaments

The processing, structure, and properties of filaments melt spun from three polypropylenes with similar rheology but substantially different crystallization kinetics were studied. The crystallization kinetics of the homopolymer was increased by the addition of a nucleating agent, whereas slower crystallization kinetics was obtained through a small amount of random copolymerization with ethylene. The relative crystallization kinetics of these three polymers was examined under quiescent conditions using differential scanning calorimetry. The technique of on-line diameter and birefringence measurement was used to show the characteristics of the on-line crystallization of the different resins. It was found that changing the quiescent crystallization kinetics by either the addition of a nucleating agent or through copolymerization with ethylene can produce profound effects on the structure and properties of polypropylene as-spun filaments when they are spun under relatively low stress and low takeup velocity conditions. Higher takeup velocities and spinline stresses reduce the effect of differences in quiescent crystallization due to the influence of on-line stress-induced (molecular orientation-enhanced) crystallization. © 1993 John Wiley & Sons, Inc.     

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。     

FeS2@TiO2 nanorods as high-performance anode for sodium ion battery

Sodium-ion battery (SIB) is an ideal device that could replace lithium-ion battery (LIB) in grid-scale energy storage system for power because of the low cost and rich reserve of raw material. The key challenge lies in developing electrode materials enabling reversible Na⁺ insertion/desertion and fast reaction kinetics. Herein, a core-shell structure, FeS₂ nanoparticles encapsulated in biphase TiO₂ shell (FeS₂@TiO₂), is developed towards the improvement of sodium storage. The diphase TiO₂ coating supplies abundant anatase/rutile interface and oxygen vacancies which will enhance the charge transfer, and avoid severe volume variation of FeS₂ caused by the Na⁺ insertion. The FeS₂ core will deliver high theoretical capacity through its conversion reaction mechanism. Consequently, the FeS₂@TiO₂ nanorods display notable performance as anode for SIBs including long-term cycling performance (637.8 mA·h·g^-1 at 0.2 A·g^-1 after 300 cycles, 374.9 mA·h·g^-1 at 5.0 A·g^-1 after 600 cycles) and outstanding rate capability (222.2 mA·h·g^-1 at 10 A·g^-1). Furthermore, the synthesized FeS₂@TiO₂ demonstrates significant pseudocapacitive behavior which accounts for 90.7% of the Na⁺ storage, and efficiently boosts the rate capability. This work provides a new pathway to fabricate anode material with an optimized structure and crystal phase for SIBs.     

几种血卟啉3,8—烷氧（硫）基衍生物产生单重态氧能力的研究

在“血卟啉衍生物”(HPD)肿瘤光动力疗法取得令人瞩目成就的同时,化学家们证明了临床使用的HPD制剂并非原意义上的血卟啉衍生物,而是一种复杂的卟啉混合物,其中血卟啉(HP),羟乙基-乙烯基-次卟啉(HVD),原卟啉(PP)约占总量的80％,Dougherty等分离得到其余20％未知结构羧基卟啉,认为此为HPD的有效成分,经进一步分析测定其主要成分是二血卟啉醚(DHE)。但最近的工作又表明,全合成得到的DHE与HPD有效成分的化学组成及生物活性亦不相同。显然这类药物组分复杂、结构的不确定限制了肿瘤光动力疗法的进一步发展。近年来,人们正试图从已知结构的化合物中探索新的光敏药物,作者在合成出一系列结构确定的单一组分血卟啉     

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。     

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.     

用瞬时法测定液体导热系数

以珠状热敏电阻为加热元件,建立了用瞬时法测定液体导热系数的装置,在25℃下用乙二醇等7个标准样品,对该装置进行了标定,平均偏差为2%.为了核实装置和所得关系式的可靠性,又测定了13个已知导热系数的样品,多数偏差在2%以内,最大偏差为5%.单次测量的精度为0.2%.本文叙述了这一方法的原理,并对实验结果进行了讨论.     

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.