弹性钢丝绳理论研究进展

对弹性钢丝绳理论的研究现状进行了较为全面、系统的介绍和总结,重点概述了离散模型的发展情况,对其它模型如半离散模型,则作了简要介绍;将几种离散模型的计算结果与实验情况进行了对照研究,提出并讨论了目前钢丝绳理论的某些不足之处及今后的研究方向．     

服从正态分布的强度变量在多个独立应力作用下的结构可靠性估计

本文讨论了服从正态分布的强度变量在(分布不一定相同的)多个独立应力作用下的结构可靠性估计.在假设应力参数已知,强度参数部分未知或全部未知的条件下,给出了结构可靠度的点估计和置信下限.     

Advanced AC calorimetry of polycaprolactone in melting region

The new capabilities of AC calorimetry, when working at frequencies above the classical limit were demonstrated. The appropriate frequency range of classical AC calorimetry was substantially enlarged. It was shown that the advanced AC calorimetry can be applied for studying dynamic heat capacity of polymers in the frequency range 0.1–1 Hz. Thus, the processes with characteristic time as short as ca. 5 s was registered. The advanced AC technique was applied for investigation of the melting kinetics in polycaprolactone. It was found that melting in polycaprolactone is related to an activated process. The activation of the melting process after a step heating is described by a stretched exponent and the decay of the melting by only one exponent at short times. The dependencies of the exponent on temperature and thermal treatment were investigated at frequencies in the range 0.1–1Hz and modulation amplitudes 0.005–0.2 K.     

含间苯基聚醚酮醚酮酮的合成和性能研究

自英国ＩＣＩ公司开发聚醚醚酮（ＰＥＥＫ）并于八十年代初期商品化以来［１］,聚芳醚酮作为一类新型结构的高性能特种工程塑料得到了惊人的发展,不同结构的聚芳醚酮相继出现．Ｊａｎｓｏｎ［２］等以对苯二甲酰氯（ＴＰＣ）和４,４′ 二苯氧基二苯酮（ＤＰＢＰ）为单...     

苯乙烯/甲基丙烯酸和苯乙烯/甲基丙烯酸(β-羟丙酯)嵌段共聚物的表面动态行为

通过测定表面动态接触角研究了两亲性的苯乙烯／甲基丙烯酸嵌段共聚物（ＰＳ ｂ ＰＭＡＡ）和苯乙烯／甲基丙烯酸（β 羟丙酯）嵌段共聚物（ＰＳ ｂ ＰＨＰＭＡ）的表面动态行为及温度、嵌段长度比等因素对其值的影响,讨论了聚合物表面当接触介质改变时链段或基团的再取向行为和表面性质     

GaAs(100)解理面的能带弯曲

在真空中解理后,用XPS测得了GaAs样品（110）断面能带弯曲的动态过程．两组重掺杂n型和p型GaAs样品的费米能级分别向禁带中间的方向移动了0.4eV和0．3eV.实验测得重掺杂n型和p型GaAs样品费米能级之差为1．3eV,它们的禁带宽度理论值为1．42eV,这说明结果是合理的．根据实验结果,对引起GaAs表面能带弯曲的可能原因进行了分析讨论．排除了本征表面态、真空中残留气体和X射线辐射等原因,认为解理过程在表面产生的缺陷和解理后表面晶格弛豫过程中产生的缺陷可能是导致能带弯曲的主要原因．     

破乳剂对复合驱乳状液的破乳机理研究

针对模拟采出液和三元复合驱矿场采出液,研究了破乳剂对复合体系界面张力和膜强度的影响.破乳剂浓度增加,二元复合体系界面张力降低,而三元复合体系界面张力升高.破乳剂分子部分顶替乳化剂分子并显著降低了界面膜强度.     

Use of immobilized amyloglucosidase as chiral selector in chromatography. Control of enantioselective retention and resolution in liquid chromatography

Summary Several mobile phase parameters were investigated for controlling enantioselective retention and resolution on a chiral stationary phase made in-house. The chiral selector was the enzyme amyloglucosidase, which was immobilized onto a silica support via reductive amination. The influences of the mobile phase pH, concentration and type of uncharged organic modifier, ionic strength and column temperature on enantios-electivity were studied. The analysis time for resolving enantiomers could be adjusted with only a minor decrease in enantioselectivity by using a high ionic strength mobile phase buffer. This indicated a retention mechanism involving ion-exchange interactions. It was further confirmed by the decreasing enantioselectivity of amines when using a mobile phase pH below the isoelectric point of the native protein. Interesting effects were observed when the organic modifier concentration was increased and also when the column temperature was raised. Both retention and enantioselectivity increased with increasing concentration of 2-propanol in the mobile phase. Examples are given where both enantioselectivity and retention increased with increasing column temperature. Thermodynamic studies were performed to calculate the entropy and enthalpy constants. The results showed that, depending on mobile phase composition, the enantioselective retention may be caused by differences in entropy or enthalpy.     

Effects of electron beam irradiation on cork volatile compounds by gas chromatography-mass spectrometry

Summary The effects of electron beam irradiation on cork volatile compounds was studied at different doses (25, 100, 1000 kGy). Volatiles were isolated from cork using the dynamic headspace-sampling technique, then identified by gas chromatography-mass spectrometry (GC-MS). Similar gas chromatographic profiles were obtained for non-irradiated and irradiated corks. Quantitative differences induced by the three doses were evaluated by calculating peak areas for each compound identified. The quantitative differences between non-irradiated corks and those irradiated at 25 kGy were significant for only a few substances, whereas significant quantitative differences were found in samples irradiated at 100 and 1000 kGy. For these doses, the content of volatile compounds generally increased, especially that of aliphatic hydrocarbons and carbonyl compounds. The behaviour of radiolytic hydrocarbons indicates that the mechanisms proposed for their formation in irradiated foods could take place even in cork.     

Electronic structure of C60 films

A complete set of fundamental optical functions of fullerite (C₆₀) films in energy ranges of 2.5–5.0 and 4.0–9.0 eV is calculated using the known spectra of the imaginary and real parts of the dielectric constant. An integrated spectrum of the dielectric constant is decomposed into elementary components. Three basic parameters of each component (the maximum and halfwidth energies and oscillator strength) are determined. Based on the known theoretical calculations of fullerite zones, a scheme of the nature of these components of the dielectric constant is suggested. Udmurt State University, 71, Krasnogeroiskaya Str., Izhevsk, 426034, Russia. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 2, pp. 227–232, March–April, 1999.