用DMSO/水复合溶剂制备PVA凝胶纺原液及其流变性能的研究

本工作以聚合度DP=1750的市售聚乙烯醇(PVA)为原料,以乙二醇(EG)及各混合比例的DMSO/水的混合物为溶剂,借助于扫描电子显微镜(SEM)和差热扫描量热法(DSC)等手段,对溶解过程作了研究。研究表明:当DMSO/水的比例为70/30时,该混合溶剂的溶解性能最好。通过对PVA—DMSO/水体系的流变研究发现,在80～100℃之间,浓度为14～17.4％时,该溶液具有很好的流变性能。     

Expression and proteolytic activity of calpain in lens epithelial cells of oxidative cataract

Objective: To study the role of calpain in the mechanism of oxidative cataract through detecting the level of intracellular free Ca^2 , the expression and proteolytic activity of calpain in the lens epithelial cells (LECs) of H2O2-induced cataract. Methods:Rat lenses were cultured in vitro and cataract was induced by H2O2. The level of intracellular free Ca^2 was measured by fluorescence determination with fura-2/AM. The expression of m-calpain protein in LECs was detected with immunohistochemical method. The proteolytic activity in LECs was measured using a fluorogenic synthetic substrate.Results: There were significant differences of the level of intracellular free Ca^2 (P=0.001, 0.000, 0.000), the expression of m-calpain (P=0.001, 0.000, 0.000) and the proteolytic activity ofcalpain (P=O.O01,0.000, 0.000) between H2O2-induced and control group at 6, 12 and 24 h, respectively. Conclusions: H2O2 can increase intracellular free Ca^2 , then enhance the expression and proteolytic activity of calpain which may play a role in the mechanism of oxidative cataract of rat.     

Relationship between toxicity and molecular volume of dioxins,organic phosphorous compounds and <Emphasis Type="Italic">n</Emphasis>-alkanols

The molecular volumes of dioxins, organic phosphorous compounds and n-alkanols were computed at the B3LYP/6-311G** level, and were then correlated with their toxicity. It was surprisingly found that there exists the so-called “critical volume of toxicity“ (CVT) in each series of compound of the present study, i.e. the toxicity increases with increase of the molecular volume when less than CVT, while decreasing with increase of the molecular volume when larger than CVT. The CVT for the three series of compounds is quite similar, ranging 0.309----0.320 nm^3. It was proposed that the ordinary linear solvation energy relationship (LSER) should be modified with respect to the new findings, and accordingly the anaesthetic potency of partial fluorinated n-alkanols was predicted.     

难熔金属梯度合金的进展

文中概述了双相结构梯度硬质合金(DP合金)的性能与结构特点以及研究现状;介绍了脱β层梯度合金形成的过程机理以及β相溶解模型;阐明了金属熔体渗透制备梯度合金的方法;介绍了硬质合金和金属陶瓷组合梯度材料强化机理和材料设计的理论基础,并介绍了近十年国内外难熔金属梯度材料的发展状况.     

Geological records of marine environmental changes in the southern Okinawa Trough

Indexes of sediment grain size,sedimentation rates,geochemical composition,heavy,minerals,benthic foraminiferal fauna,indicator species of the Kuroshio Current,paleo-SST and carbonate dissolution of core E017 conformably suggest a great marine environmental change occurring at about 10.1-9.2cal.kaBP in the southern Okinawa Trough,which may correspond to the strengthening of the Kuroshio Warm Current and re-entering the Okinawa Trough through the sea area off northeast Taiwan.The invasion of Kuroshio current has experienced a process of gradual strengthening and then weakening,and its intensity became more fluctuation during the last 5000 years.Compared to the transition of sediment grain size,geochemical composition and heavy minerals,the foraminiferal faunas show a 900-year lag,which may indicate that the invasion of Kuroshio Current and the consequent sea surface and deep-water environmental chanages is a gradual process,and fauna has an obvious lag compared to environment altering.The carbonate dissolution of the Okinawa Trough has had an apparent strengthening since 9.2cal.kaBP,and reached a maximum in the late 3000 years,which may be caued by the deep-water environmental changes due to the invasion of Kuroshio Current.     

2MgO·2B_2O_3·MgCl_2·14H_2O溶解及相转化的动力学机制研究

研究了温度、搅拌速度对２ＭｇＯ·２Ｂ２Ｏ３·ＭｇＣｌ２·１４Ｈ２Ｏ在水中溶解及相转化动力学的影响。给出了溶解和转化结晶动力学方程;根据Ａｒｒｈｅｎｉｕｓ公式,估算了溶解和结晶反应的活化能。依据反应级数、活化能及搅拌效应,确定了该复盐的溶解和转化结晶反应动力学机制。     

珠江口表层水中主要常量离子的研究

１９９４年９月采集了珠江口表层海水水样,并对其溶解态的Ｋ＾＋、Ｎａ＾＋、Ｃａ＾２＋、Ｍｇ＾２＋、ＳＯ４＾２－、Ｃｌ等化学要素进行了测定。结果表明,珠江口调查海域表层水中溶解态的Ｋ＾＋、Ｎａ＾＋、Ｃａ＾２＋、Ｍｇ＾２＋、ＳＯ４＾２－主要受陆源淡水与外海水物理混合稀释的影响,与Ｃｌ具有良好的直线正相关,Ｃａ＾２＋／Ｃｌ、ＳＯ４＾２＋／Ｃｌ明显高于大洋水相应比值,Ｎａ＾＋／Ｃｌ、Ｍｇ＾２＋／Ｃｌ略高,而     

对吕·查德里原理的二点讨论

本文讨论了吕·查德里原理在中文化学教科书中的两种表述以及吕·查德里原理在溶解平衡体系中的应用。     

甲基丙烯酸甲酯与琼脂糖的接枝反应及其共聚物的研究

本文研究硝酸铈铵作引发剂，甲基丙烯酸甲酯与琼脂糖的接枝共聚反应．考察了引发剂浓度、单体浓度、反应温度、反应时间及加料顺序对转化率，接技效率等的影响．红外光谱及热分析结果表明，所得产物为接枝共聚物．共聚物的玻璃化转变温度随接枝百分率的增加而降低，接枝共聚物可溶解于部分有机溶剂剂，并具有良好的热压成型性质．     

碳酸盐及其酸式盐溶解度的讨论

采用热力学原理和溶解自由能数据，分析了易溶碳酸盐的溶解度大于其酸式盐式盐的溶解度以及与一般碳酸盐的情况相反的原因。Ｎａ２Ｃｏ３、ＮａＨＣＯ３等类盐溶解度影响的主要因素是由于溶解焓变不同，而影响的ＣａＣｏ３、Ｃａ（ＨＣＯ３）２等类盐溶解度的主要原因则是由于溶解熵变的不同所引起的。