低温反相悬浮合成AA/AM共聚型吸水树脂

采用氧化还原引发体系，反相悬浮法低温合成AA／AM共聚型吸水树脂。研究了不同引发体系、单体组成、交联剂和引发剂浓度、温度、单体中和度对共聚物吸液能力的影响。与单一引发剂相比，采用复合引发体系，反应温度降低，聚合时间缩短，产物吸水速度和吸液能力高于聚丙烯酸钠，保水性略低于后者。共聚物最大吸液能力为：Q去离子水=970mL／g，Q生理盐水=129mL／g，Q人工尿=130mL／g。     

Stress-corrosion cracking of a monel 400 tube

A bent Ni-Cu Monel 400 alloy tube, which operated as part of a pipeline in a petrochemical distillery installation, failed by through-thickness cracking. The pipeline was used to carry a stream of gaseous hydrocarbons containing hydrochloric acid (HCl) into a reaction tower. The tower provided a caustic solution (NaOH) to remove HCl from the stream, before the latter was directed to a burner. Metallographic examination showed that the cracks were intergranular and were frequently branched. Although nominal chemical composition of the component was found within the specified range, electron dispersive analysis by X-ray (EDXA) indicated significant segregation of sulfur and chlorine on grain boundaries. Failure was attributed to hypochlorous-acid (HClO)-induced stress-corrosion cracking (SCC). The HClO was formed by the reaction of HCl with atmospheric O₂, and the oxygen entered the tube during shutdowns/startups of the installation. Residual stresses, originating from the in situ bend forming of the tube during assembly of the line, provided a driving force for crack growth, and the segregation of sulfur on grain boundaries enhanced the susceptibility of the material to cracking.     

几种聚乳酸／生物活性陶瓷复合材料细胞相容性的比较

采用溶解共混法制备含30%硅灰石的聚乳酸/硅灰石新型生物医用复合物膜.将大鼠成骨细胞ROS 17/28系种植在复合物表面使其存活,考察生长情况和复合物的生物活性,并与目前研究应用较多的聚乳酸/羟基磷灰石、聚乳酸/磷酸三钙及聚乳酸/珍珠层粉复合物进行比较.荧光染色实验及MTT测试表明,4种复合物膜表面细胞均可以正常的生长和增殖,且呈现出聚乳酸/珍珠层粉>聚乳酸/硅灰石>聚乳酸/羟基磷灰石>聚乳酸/磷酸三钙的结果,说明聚乳酸/硅灰石复合物材料具有较好的细胞相容性,适于应用在骨修复及骨组织工程领域.     

蒙旦蜡化学组成的研究Ⅲ游离蜡酸

本文将阴离子树脂交换色谱法分离出的蒙旦蜡游离酸通过重氮甲烷(CH_2N_2)酯化,得到蜡酸甲酯。经GC/MS分析,碳数分布为XDCWFAC_(20)～C_(84),XDOWFA C_(20)～C_(34),SLCWFA C_(20)～C_(33),SLOWFA C_(20)～C_(33)。经硝酸氧化后,游离酸的碳数分布未发生变化。气相色谱分析结果表明,正构一元烷酸在游离蜡酸中的百分含量为:XDCWFA50.52,XDOWFA78.47;SLCWFA83.01,SLOWFA97.63。在纯蜡中相应百分含量为:6.32,32.96,35.69,54.67。最高含量碳分布:SLCWFA和SLOWFA中为C_(28),XDCWFA为C_(28),而XDOWFA为C_(26)。与蒙旦蜡烷醇一样,表现出很好的奇偶规律,即偶数碳烷酸占绝对优势。XDCWFA和XDOWFA有着比SLCWFA和SLOWFA更复杂的化学结构。     

固体酸催化剂上线性烷基苯生成反应动力学研究

在确定线性烷基苯反应生成动力学方程基础上 ,在消除外扩散影响前提下 ,用苯烯摩尔比为 1 0∶1的反应原料 ,在中孔分子筛负载杂多酸催化剂上进行苯与长链烯烃烷基化反应 ,采用气相色谱法分析反应组成 ,获得了不同反应温度、质量空速、催化剂粒度的烷基化反应试验数据。对模型进行参数估值 ,确定了线性烷基苯生成反应速率常数、扩散系数 ,以及反应活化能和扩散活化能参数 ,建立了考虑内扩散影响的线性烷基苯生成反应动力学模型 ,并开展模型评价、模型预测和反应规律研究。研究结果表明 ,线性烷基苯收率试验值和计算值的相关指数为 0 .9892 ,说明该模型具有较强的拟合试验数据能力 ,可信度较高。模型预测结果表明 ,线性烷基苯收率随着反应温度提高和原料与催化剂接触时间延长而不断提高 ,随催化剂粒径增大而降低。     

Rapid and Sensitive Liquid Chromatography-Tandem Mass Spectrometry for Quantification of Glycyrrhetic Acid in Human Plasma

A simple, rapid and sensitive liquid chromatography-tandem mass spectrometry(LC-MS/MS) for the determination of glycyrrhetic acid in human plasma with ginsenoside Rh2 as internal standard was developed and validated. The plasma samples were prepared via liquid-liquid extraction with ethyl acetate. Chromatographic separation was accomplished on a Venusil MP-C18(50 mm×2.1 mm, 5μm i.d.) column at 25℃. The mobile phase consisted of acetonitrile/5 mmol·L-1 ammonium acetate(10:90, volume ratio) at a flow rate of 0.4 mL/min. Negative electrospray ionization was utilized as the ionization source. Glycyrrhetic acid and internal standard were determined via the mutiple reaction monitoring of precursor→production ion transitions at m/z 469→425, 409 and m/z 621→161,respectively. Each sample was chromatographed within 2.5 min. The lower limit of uantification was 0.50 ng/mL for 200 μL of plasma sample and the linear range was from 0.50 ng/mL to 800 ng/mL. The intra-and inter-day precisions were less than 8.76% in terms of relative standard deviation(RSD), and the accuracy was within a range of -3.25%-1.32% in terms of relative error(RE). The method was successfully applied to the pharmacokinetic studies of glycyrrhetic acid in healthy male Chinese volunteers after a single oral administration of 75 mg of glycyrrhizin.     

采用DOE实验设计方法改进电容器级铌粉酸洗工艺

采用DOE实验设计方法,对制备电容器用铌粉的酸洗除杂工艺进行研究,确定了影响铌粉性能的关键因素是酸洗除杂工艺使用酸的浓度和酸洗时间。通过关键因素的全因子正交试验,对产品质量和工艺参数进行量化分析,确定最佳的酸洗工艺,可有效减低和控制电容器级铌粉中的主要C、O非金属及Fe、Ni、Cr金属杂质含量,降低电容器级铌粉的漏电流和损耗,提高电容器级铌粉的性能。     

PE－AA辐射接枝共聚合的反应历程研究

研究了聚乙烯（ＰＥ）与丙烯酸（ＡＡ）、甲基丙烯酸（ＭＡＡ）的接枝共聚反应，探讨了接枝反应过程及特征：单体首先在ＰＥ表面接枝，然后进入内部进行本体接枝。研究表明：表面接枝为动力学控制，本体接技系扩散控制，单体在膜内的扩散与单体极性及聚合物的结晶度等有关     

碱性氨基酸辐射保护机理的电子自旋共振研究

本文研究了组氨酸和精氨酸对胸腺嘧啶的辐射保护机理。用ESR方法和分子轨道计算确证其辐射保护是由于电子清除和从胸腺嘧啶阴离子向碱性氨基酸的转移。碱性氨基酸的亲电子性能随质子化程度而异,在pH=7的条件下,组氨酸对胸腺嘧啶的辐射保护机理可能是电子转移与氢原子转移的协同过程。