On the effect of montmorillonite in the curing reaction of epoxy nanocomposites

The procedure for the fabrication of epoxy-based polymer layered silicate nanocomposites is important in respect of the nanostructure that is developed. To further our understanding of this, the influence of an organically modified clay (montmorillonite, MMT) on the curing kinetics of an epoxy resin has been studied by differential scanning calorimetry. Clay loadings of 10 and 20 mass% are used, and isothermal as well as dynamic cures have been investigated. For both cure schedules the effect of the MMT is to advance the reaction. Kinetic analysis yields values for the activation energy, but shows that the reaction cannot be described simply by the usual autocatalytic equation. The glass transition of the cured nanocomposites is lower than that for the cured neat resin, a result that is attributed to homopolymerisation taking place in addition to the epoxy–amine reaction.     

Solid-state interactions and drug release of teicoplanin in binary combinations with peracetylated α-, β-, and γ-cyclodextrins

Triacetyl α-cyclodextrin, triacetyl β-cyclodextrin and triacetyl γ-cyclodextrin were tested as possible hydrophobic carriers to prolong the release of hydrophilic teicoplanin (TCP). Physical–chemical characterization of individual components, drug-carrier physical mixtures at 0.5, 0.67 and 0.75 mass fraction of carrier, and the respective interaction products by kneading or evaporative crystallization under microwave irradiation was carried out using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). In vitro drug release in pH 7.4 phosphate buffer at 37 °C was determined by intrinsic dissolution rate (IDR) measurements on non disintegrating compressed discs. Solid-state interactions of TCP with triacetyl α-cyclodextrin by evaporative crystallization and kneading and with triacetyl β-cyclodextrin by evaporative crystallization (probably resulting in carrier amorphization) were demonstrated. The role of carrier hydrophobicity, carrier mass fraction and preparation method of solid drug-carrier combinations on solid-state drug-carrier interactions and slowing down of TCP release was assessed. Modulation of drug release can be achieved using TCP-triacetyl γ-cyclodextrin combinations at 0.5 mass fraction of carrier.     

催化裂解富气吸收液的离子色谱法测定

以催化裂解富气吸收液为测定对象，建立吸收液中目标离子（包括NO2^-，NO3^-，SO4^2-）的离子色潜分析方法。在选定色谱柱的前提下，通过优化淋洗液浓度等色谱条件，实现了在大量干扰离子S^2-及与SO4^2-相邻的未知离子存在的三乙醇胺溶液中目标离子的定量。方法的检出限分别为NO2^- 62μg／L，NO3^- 26μg／L，SO4^2- 90μg/L，RSD值为0．73％～1．19％，加标回收率在91％～109％。     

三线性直接分解法分析高维灰色体系

对于由多个两维测量数据组成的三维阵，本文提出一种新三线性直接分解方法。采用高维ＰＣＡ分解，从三维阵中直接提取抽象光谱和抽象浓度，再结合ＱＺ算法，唯一地确定混合物中各组分光谱的浓度。该方法可以排除其它未知组分的干扰，适用于高维灰色体系定性定量分析和多点校准。用模拟数据讨论了光谱分离度对该方法的影响，应用于混合维生素Ｂ１、Ｂ２和Ｂ６的荧光分析，求得的光谱和浓度与实验值吻合很好。     

12,14-二羟基紫韧革烯的分离和结构测定

由紫韧革菌(Stereum purpureum)代谢产物中分离出一个新的三环倍半萜烯醇(sterpurenol), 12,14-二羟基紫韧革烯。用二维核磁共振确定了它具有紫韧革烯(sterpurene,1)的骨架及它的整个分子结构。     

La2O3对氧化铝透明陶瓷显微结构和透光性能的影响

采用传统无压烧结工艺在氢气氛下制备Al2O3透明陶瓷。实验结果表明：MgO和La2O3复合添加时，随着La2O3掺杂量的增加体积密度总体上保持上升的趋势。随着保温时间的延长，陶瓷的致密化程度增大，残余气孔逐步排出，晶粒进一步长大。采用La2O3和MgO复合添加比单独掺入MgO陶瓷样品透过率更高，掺杂效果更好。在烧结温度为1750℃，保温时问为1h条件下，在波艮为300～800nm测试范围内，陶瓷样品的全透过率大于82％，最大值为86％。     

气相色谱法分析生产过程中的邻甲基苯胺

气相色谱法测定工业生产过程中邻甲基苯胺及其杂质邻硝基甲苯、间甲基苯胺、对甲基苯胺的含量。4种物质的浓度与色谱峰面积呈良好的线性关系,测定结果与标准值基本一致。邻甲基苯胺、邻硝基甲苯、间甲基苯胺、对甲基苯胺的RSD分别为0.0025%、1.4081%、0.9929%、1.1365%,检出限分别为0.065、0.044、0.062、0.056mg/L。     

1，2—二氯丙烷裂解反应光窗结焦机理的研究

有机化合物在光窗上的结焦严重地影响激光引发化学反应及光学原位实时探测。本文报道在1，2－二氯丙烷反应系统中，光窗结焦现象同时存在于激光引发反应及热反应过程中，对光窗在300℃条件 下的结焦机理研究表明，少量氧气在光窗结焦过程中起关键作用。结焦前驱体的红外光谱研究表明，前驱体的可能结构为1－丙炔－1，3－二醇的缩聚体。该化合物极易通过缩聚反应形成更大的分子，最终导致光 窗结焦。对系统及反应物进行彻底除氧，光窗结焦现象大为改善。     

CO氢化催化剂表面活性位的动态法研究

用程序升温表面反应(TPSR)和程序升温还原(TPR)以及过渡应答(TR)等动态手段研究Ni/Al_2O_3催化剂表面上CO氢化反应的活性位状况。结果表明, 催化剂表面存在两种类型的活性位。其中A位来自表面上的聚晶体Ni, B位来自Ni与载体Al_2O_3强相互作用形成的Ni-Al化合物。实验结果还表明, CO在两个活性位都有吸附, 但在有H_2参与的条件下, 会影响二个活性位上的CO吸附量。     

Chelatometric titration of tin in non-ferrous alloys with hedta

A new titrimetric method for determination of tin (4%) in aluminium alloys, tin- and lead-base alloys, solders, white bearing alloys, special bronzes and silver brazing alloys is proposed. HEDTA, Semi-Xylenol Orange and bismuth perchlorate are used as titrant, indicator and back-titrant respectively. Measures are taken to overcome the hydrolysis of Sn(IV). Monochloroacetic acid and ethylene glycol are added as auxiliary agents. The standard deviation of this method was found to be 0.2 mg and its coefficient of variation to vary from 0.25 to 2%, according to amount of tin. A novel method of sample decomposition and a modified method for separating Sn(IV) are also suggested.