Polystyrene Suspension Polymerization: The Effect of Polymerization Parameters on Particle Size and Distribution

Effects of polymerization parameters are studied to better understand interactions between parameters in stirred-tank polymerization reactors and to derive a regression model correlating polymer particle size and particle-size distribution with agitator speed, agitator diameter, tricalcium phosphate, dodecyl benzene sodium sulfonate concentrations, and mass cycle period. The derived equations give way to prediction of the polymerization conditions in order to obtain desired particle size and particle-size distributions which covers particle sizes between 0.3 and 5 mm. The roles of some other parameters and limiting agitation parameters are also investigated.     

Improved cure optimization in pultrusion with pre-heating and die-cooler temperature

Optimization studies are performed on the pultrusion of a thermosetting composite. The three-dimensional finite element/nodal control volume procedure developed for simulation and optimization of the process is employed for this purpose. The aim of optimization is to achieve the desired degree of cure with minimum local variations across the pultrudate cross-section. The die-heating environment is optimized for a few cases with different initial temperatures for a glass/epoxy wet preform and for the cooler installed within the pultrusion die near its entrance. The role of these temperature parameters in moderating the optimization constraints is examined. Simultaneous optimization of die-heater temperatures and pull-speed is also considered. It is observed that the temperature overshoot within the composite pultrudate can be reduced and better optimization results can be achieved by a proper choice of a pre-die temperature for the composite and the die-cooler temperature.     

溶剂萃取在无机盐工业中的应用和研究

溶剂萃取是一种高效的分离方法,投资少,无污染,应用萃取富集、分离、提纯,可以由矿石直接生产金属无机盐,纯度高、成本低。将萃取用于无机盐制备开创出许多新型高效流程,利用谇取技术开发、改进的许多碱土金属无机盐生产流程可提高回收率和产品纯度、降低生产成本。     

大型工业厂房可靠度分析方法的研究

以可靠度理论为基础 ,建立了厂房系统与子系统的层次概率分析 (AHP)模型 ,重点探讨了承重结构系统的传力树分析方法 ,在同一棵传力树内建立了直接构件和间接构件的概念 .分析了厂房系统的子系统之间、子系统的传力树之间、传力树内的直接构件和间接构件之间的逻辑关系 ,从而得到了大型工业厂房系统可靠度分析方法的实用计算方法 .     

Aging, hearing acuity, and the attentional costs of effortful listening.

A dual-task interference paradigm was used to investigate the effect of perceptual effort on recall of spoken word lists by young and older adults with good hearing and with mild-to-moderate hearing loss. In addition to poorer recall accuracy, listeners with hearing loss, especially older adults, showed larger secondary task costs while recalling the word lists even though the stimuli were presented at a sound intensity that allowed correct word identification. Findings support the hypothesis that extra effort at the sensory–perceptual level attendant to hearing loss has negative consequences to downstream recall, an effect that may be further magnified with increased age. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

立式配平转台工作原理及数值仿真研究

为了验证立式配平转台原理的正确性,建立了配平转台的力学模型,并通过动力学仿真求出了当旋转体存在动不平衡量时,水平方向和垂直方向两测力仪的输出值,在此基础上对配平修正过程进行了数值仿真．仿真结果表明,配平修正过程是收敛的,说明配平转台在原理上是正确的．仿真结果可为配平转台的设计提供初步依据．     

On the optimum design of rotating two-layered composite tubes subject to internal heating or pressure

Subject of this analytical investigation is a rotating two-layered hollow cylinder under generalized plane strain subject to an elevated temperature at the inner surface or to internal pressure. It is presupposed that the inner cylindrical layer consists of the heavier material, whereas the outer layer is made of a material with lower density, like for example in a steel/aluminum tube. Criterion for the maximum permissible stress is the yield criterion by von Mises, and the device is optimized with respect to its weight. It is found that plasticization may start at different radii, and the study provides not only a comprehensive overview of the elastic limits of composite tubes of the above type but also a straightforward procedure for determining the optimum composition.     

Genetic polymorphism of the 3' VNTR region of the human dopaminergic function gene DAT1 (human dopamine transporter gene) in the Mongolian population

The hypervariable region of the dopamine transporter gene (DAT1) was amplified from samples in the Mongolian population. This region includes a variable number of tandem repeats of a 40-bp core unit in the 3' untranslated region of DAT1. Vandenbergh et al. (1992) reported variability in the number of repeats of this 3' flanking region ranging from 3 to 11 times in white and black populations. We examined polymorphism at the DAT1 locus in 78 native Mongolian subjects. We found alleles with 7 to 13 repeats, which is different from the findings of Vandenbergh et al. (1992). The allele distribution of the Mongolian population is similar to that in the Japanese population, reported previously by Nakatome et al. (1995). Chi-square analysis showed a significant lack of homogeneity between our findings in Mongolian subjects and those reported previously in white and black populations. The DAT1 locus was estimated to have a heterozygosity index of 14.1%, and the polymorphic information content was calculated to be 0.16.     

Prolonged effect of troglitazone (CS-045) on xenograft survival of hybrid artificial pancreas

Troglitazone (CS-045), a thiazolidinedione derivative, is a new oral antidiabetic agent that enhances insulin sensitivity and improves insulin responsiveness. In this study we examined the effects of CS-045 on the survival of xenografted bioartificial pancreas. Isolated rat islets were microencapsulated with three-layer agarose microcapsules (polybrene, carboxymethyl cellulose, and an agarose-polystyrene sulfonic acid mixture). Diabetes was induced by intraperitoneal injection of streptozotocin 220 mg/kg. Recipient diabetic mice were separated into two groups. In the CS-045 treated group, the recipient mice were given feed mixed with CS-045 (0.2% w/w) starting from 1 wk before transplantation up to graft failure. The mice in the control group had feed without CS-045. Three hundred microencapsulated rat islets were xenotransplanted into the intraperitoneal cavity of each recipient mouse in both groups. One month after xenotransplantation, IVGTT was performed for all recipients. Xenotransplantation of 300 rat islets in microcapsules decreased the nonfasting blood glucose levels of both groups within 2 days. In the CS-045-treated group (n = 3), the normoglycemic period lasted for more than 1 mo without administration of immunosuppressive drugs (45 +/- 4.3 days). However, in the control group (n = 4), the blood glucose levels of all recipients were already elevated on day 4. In the IVGTT study, the glucose assimilation was markedly and significantly better in the CS-045-treated group than in the control group (K = 1.7 +/- 0.1 vs. 0.7 +/- 0.28 respectively, p < 0.01). This study demonstrates that a newly developed oral antidiabetic agent, CS-045 could favorably ameliorate the diabetic state of the recipients xenotransplanted with the bioartificial pancreas, leading to an improved glucose tolerance and longer xenograft survival.     

ICS-SVM: A user retweet prediction method for hot topics based on improved SVM

In social networks, many complex factors affect the prediction of user forwarding behavior. This paper proposes an improved SVM prediction method for user forwarding behavior of hot topics to improve prediction accuracy. Firstly, we consider that the improved Cuckoo Search algorithm can select the optimal penalty parameters and kernel function parameters to optimize the SVM and thus predict the user's forwarding behavior. Secondly, this paper considers the factors that affect the user forwarding behavior comprehensively from the user's own factors and external factors. Finally, based on the characteristics of the user's forwarding behavior changing over time, the time-slicing method is used to predict the trend of hot topics. Experiments show that the method can accurately predict the user's forwarding behavior and can sense the trend of hot topics.