Deposition of Brownian particles in packed beds

An analysis is presented to describe the deposition of Brownian particles from suspensions flowing through granular media. The constricted tube porous media model recently proposed by Payatakes et al.[8] was used to characterize the media and the deposition process was assumed to be controlled by convective diffusion as well as the nature of the surface interaction between the media grains and the Brownian particles. Three different tube configurations were considered and the differences among the results were found to be relatively unimportant. Agreement between the analysis and available experimental data was found to be reasonably good for the limiting case when the surface effect is favorable.     

Bubble dissolution with chemical reaction

The dissolution of an isolated stationary gas bubble, enhanced by a chemical reaction, in a large body of liquid is investigated. A theoretical model which properly accounts for the movement of the interface due to dissolution is formulated and solved using the method of finite differences. The finite difference results are used as a standard of comparison for the testing of various approximate solutions. These include a perturbation expansion, a quasi-stationary approximation and a quasi-steady approximation. The results of this work indicate that the quasi-steady approximation, which provides very simple analytical solutions, is an excellent one in the presence of a sufficiently rapid chemical reaction.     

ZLI－1565液晶纯相位调制特性的实验研究

本文简介了国内外向列相液晶相位调制特性的研究概况，对ＺＬＩ－１５６５型平行、扭曲型向列相液晶的相位调制特性进行了实验研究。结果表明平行式向列液晶相移量大、光强变化小，并利用这一特性，将相移技术引入到剪切电子散斑干涉术中，提高了检测精度；相移方法简单、可靠。用该系统进行应变场的测量实验，取得了满意的效果。     

Is tubal sterilization associated with an increased risk of subsequent hysterectomy but a decreased risk of ovarian cancer? A review of recent literature

Recent epidemiologic studies have suggested that tubal sterilization (TS) may lead to an increased incidence of subsequent hysterectomy but a decreased risk of ovarian cancer. This review evaluates the nature and magnitude of these two relationships, which should be of great concern and interest to women, clinicians and the administrators of family planning programs. The positive relationship between TS and subsequent hysterectomy is more likely to be of a motivational rather than biological nature, and a considerable number of unnecessary hysterectomies after TS could be avoided by changing the attitudes of physicians and women. The inverse relationship between TS and ovarian cancer appears causal, although the exact biological mechanisms remain to be clarified. Theoretically, this non-contraceptive beneficial effect of TS could be used as a primary preventive measure to curb the incidence of the highly fatal ovarian cancer. However, a number of medical, ethical, and economic questions attending use of a generally irreversible contraceptive procedure as a preventive measure must first be answered. The issue of whether TS is associated with any long-term sequelae, and, if so, whether the association is of a cause-and-effect nature or a by-product of time passage and aging of the woman, should be addressed by well-designed studies.     

Effects of ductility on seismic response of piping systems and their implication on design and qualification

This study is concerned with the inelastic seismic response of nuclear power plant piping systems. Two systems are examined. The first one is an idealized four-equal-span pipe run and the second one consists of two configurations modified from an existing pipe run. Detailed finite element seismic time history analyses are performed using the computer program. By varying the various geometrical and physical parameters, calculations are made for a total of 76 cases. The results show that ductility generally contributes to reducing the response of piping systems. An empirical relation between the support load reduction factor and support ductility demand is given and a chart and simple procedures are suggested for the design and qualification of piping supports taking ductility into consideration.     

Study of segmented ethylene terephthalate–caprolactone copolymer by differential refractometry and light scattering

A segmented ethylene terephthalate (ET)–caprolactone (CL) copolymer was characterized by light scattering in chloroform tetrahydrofuran and butanone. The flexibility of the copolymer chain is comparable with that of typical flexible chains, such as polystyrene. In the process of applying the Bushuk–Benoit light scattering theory to the segmented PET–PCL copolymer, we encountered not only the problem of finding three solvents with different refractive index but also the problem of determining the specific refractive index increments for the PET and PCL segments in the copolymer, i.e., ν_PET and ν_PCL . In principle, the approximate values of ν_PET and ν_PCL can be obtained from the PET and PCL homopolymers, respectively. In reality, it involves many practical problems, e.g., to find three solvents not only for copolymer but also for the PET and PCL homopolymers. In this study, a different method was used to find both ν_PET and ν_PCL , wherein the ν values of at least two segmented PET–PCL copolymers with different PET compositions were used. With ν_PET , ν_PCL , and ν, we characterized the absolute molecular weight. Further, we show that the composition of an unknown segmented PET–PCL copolymer can be estimated from ν_PET , ν_PCL , and ν. © 1994 John Wiley & Sons, Inc.     

Mixing of pharmaceutical solids. IV. Effects of concentration and material properties on multicomponent mixing of cohesive powders

The results of mixing three cohesive drugs in different concentrations with a fixed concentration of a cohesive excipient were compared. The mixing index, s/σ_A, which is based on setting standard specifications was used to analyze the data. The results suggested that the homogeneity of the three drug components with similar individual concentrations (6 – 7%) approached acceptable homogeneity at a faster rate compared to the mixture where the concentration of drugs varied over a wider range (2 – 12%). However, the mixing of the three drugs in similar concentrations indicated that the rate of mixing of the drug components was dependent on the material properties, such as tensile strength of the drugs and the excipient.     

硒与老鹰茶黄酮复配对山茶油的抗氧化效果

为了促进天然抗氧化剂的开发,以过氧化值为指标,以硒代蛋氨酸、甲基硒代半胱氨酸、亚硒酸钠和老鹰茶黄酮(HTTF)为研究对象,采用Schaal烘箱法对比单独和复配使用对山茶油的抗氧化效果。结果表明：硒代蛋氨酸、甲基硒代半胱氨酸和亚硒酸钠对山茶油均有抗氧化效果,且加入量越高,抗氧化效果越好;硒代蛋氨酸和亚硒酸钠与HTTF复配对山茶油的抗氧化效果均优于各单一组分,而甲基硒代半胱氨酸与HTTF复配对山茶油的抗氧化效果优于HTTF,但逊于甲基硒代半胱氨酸;硒代蛋氨酸、甲基硒代半胱氨酸、亚硒酸钠和HTTF单独使用和复配使用对山茶油的抗氧化效果均弱于TBHQ。综上,不同的硒与HTTF复配对山茶油的抗氧化效果不同。