弱碱性条件下α,β-二溴-3-(3'-硝基苯基)丙酸的消除反应研究

以α,β-二溴3-(3'-硝基苯基)丙酸为原料,在不同浓度的乙醇溶液中,以碳酸氢钠和碳酸钠等弱碱为消除试剂进行消除反应,实验表明α,β-二溴-3-(3'-硝基苯基)丙酸经消除反应可得到3-硝基苯乙炔和3-(3'-硝基苯基)-2,3-环氧丙酸,同时采用核磁共振谱和液质联谱进行了结构表征,并对其消除反应的机制进行了探讨.     

3-氧代和4-氧代紫罗兰醇乙酸酯的合成路线改进

以叔丁基过氧化氢(TBHP)和次氯酸钠氧化α-紫罗兰酮,得到关键中间体3-氧代-α-紫罗兰酮(1),同时,进行了条件试验,最佳条件为:在室温条件下,无水乙腈和K2CO3中,n(α-紫罗兰酮):n(TBHP):n(NaCIO)为1:8:3时,反应得到产物,最佳得率为50.9%.产物再经硼氢化钠选择性还原得氧代紫罗兰醇,经...     

合成镁铝尖晶石中β″-Al2O3结构的研究

采用工业氧化铝和轻烧氧化镁烧结合成镁铝尖晶石（MgAl2O4,MA）,当MA中Al2O3含量超过72%（质量分数,下同）时,在晶间生成少量呈板状自形习性的晶体,借助于场发射扫描电子显微镜（field emission scanning electron microscope,FESEM）、能谱仪和X-射线衍射仪研究了晶...     

Influence of porosity on the mechanical properties of microporous β-TCP bioceramics by usual and instrumented Vickers microindentation

Beta-tricalcium phosphate [Ca₃(PO₄)₂, β-TCP] is a bioresorbable material showing an excellent biocompatibility. However, sintering of β-TCP is difficult and the material presents poor mechanical strength and a low resistance to crack-growth propagation. In this study, influence of the porosity on the hardness and the elastic modulus is studied by means of usual and instrumented microindentation tests. Nevertheless, indentation diagonals measurement by optical observations is not accurate due to the crack formation around the residual indent. That is why instrumented indentation test which allows deducing the hardness and the bulk modulus from the load-depth curve analysis is used as an alternative method. The corresponding hardness number can be calculated by using the maximum indentation depth (Martens Hardness) or the contact depth determined by Oliver and Pharr's method (Contact Hardness). But in order to give representative values when comparing classical and instrumented hardness measurements, Martens hardness is preferred because its value can be directly related to the value of the Vickers hardness number by simple geometrical considerations.In this work, bioceramics were produced by conventional sintering of β-TCP powders synthesized by aqueous precipitation. Different process conditions were chosen to obtain microporous ceramics with a porosity rate between 0 and 14% in volume. As main results, the elastic modulus is found decreasing between 166 GPa and 108 GPa and the hardness number from 4.4 GPa to 2.2 GPa when increasing the porosity rate. A model connecting mechanical properties to porosity rate and grain arrangement is validated for the elastic modulus whereas deviation is observed for the hardness number. However, we propose an original approach where the relative variation of the two mechanical properties can be expressed with a unique relation as a function of the porosity volume fraction.     

β-Sialon对刚玉质耐火材料性能影响的研究

在刚玉质耐火材料的基质中引入硅粉和铝粉,通过原位氮化反应形成β-Sialon,并制备β-Sialon结合刚玉复相材料。研究了β-Sialon生成量对材料的物理性能、力学性能、热震稳定性等性能的影响。用XRD和SEM分析了材料的物相组成和显微结构。     

A novel route for the preparation of thermally sensitive core-shell magnetic nanoparticles

This study has developed a novel route for the synthesis of the thermoresponsive core-shell nanoparticles that consist of the magnetite core and the poly(N-isopropylacrylamide) (poly(NIPAAm) shell in aqueous medium. Magnetic nanoparticles (MNPs) were coated first with oleic acid (OA) and then vinyl carboxylic acid-β-cyclodextrin (MAH-β-CD). The OA-MNPs and the MAH-β-CD-MNPs showed mono-dispersion in n-hexane and aqueous medium, respectively. NIPAAms were successfully polymerized from the vinyl double bonds of the MAH-β-CD MNPs and cross-linked with N, N-methylenebisacrylamide (MBA) to make the stable thermoresponsive core-shell morphology with the MNP core and the poly(NIPAAm) shell (poly(NIPAAm)-MNP). The aqueous solutions dispersed with poly(NIPAAm)-MNPs showed magnetic heating due to a superparamagnetic property, and the poly(NIPAAm) shell shrank above its LCST temperature. The combination of these properties are potentially important in the targeted delivery of therapeutic agents in vivo, hyperthermic treatment of tumors, magnetic resonance imaging (MRI) as a contrasting agents, tissue repair, immunoassay, cell separation, biomagnetic separation of biomolecules, etc.     

乙烯基三（β-甲氧基乙氧基）硅烷的合成工艺研究

以乙烯基三氯硅烷（ViSiCl3）、甲醇（MeOH）及乙二醇甲醚为主要原料,采用醇解、酯交换两步反应合成了ViSi（OEtOMe）3。确定了其最佳醇解反应条件为：n（ViSiCl3）：n（MeOH）为1：3.6,反应温度为80℃,在此条件下中间体ViSi（OMe）3收率在85%左右;最佳酯交换反应条件为：n（ViSi（OMe）3）：n（乙二醇甲醚）为1：3.6,反应温度为100℃,反应时间为1.5～2.0h,产物ViSi（OEtOMe）3酯交换的单程收率可达到92%。最后采用GC-MS法对最终产物结构进行了表征。     

纤维增强等规聚丙烯复合材料的界面β横晶研究进展

综述了近年来纤维增强等规聚丙烯复合材料界面β横晶的研究进展。重点介绍了几种可获得界面β横晶的方法。从结晶动力学的角度阐述了界面β横晶的形成条件及结构特点,并对影响界面β横晶形成的因素进行了分析。     

气相色谱法测定β-D-葡萄糖五乙酸酯含量

采用三氟丙基甲基聚硅氧烷毛细管色谱柱,用面积归一法进行β-D-葡萄糖五乙酸酯的气相色谱分析.结果表明,该方法操作简便、快速,分离效果好,准确度高,回收率在99.58％～ 100.4％,可用于β-D-葡萄糖五乙酸酯的产品质量分析.     

MgO含量对微晶玻璃结构及性能的影响

锂铝硅系微晶玻璃是一种具有优异的光学、力学性能的微晶玻璃材料。本文制备了以透锂长石和二硅酸锂为主晶相的锂铝硅系透明微晶玻璃,并通过DSC、XRD与SEM研究了MgO含量对该微晶玻璃析晶行为及结构的影响,利用维氏硬度、抗弯强度等测试方法研究了MgO含量对该微晶玻璃力学性能的影响。结果表明,当MgO含量(质量分数)从0%增加至3%,基础玻璃的析晶温度从771 ℃降低至729 ℃,析晶能力增强,微晶玻璃的结晶度从62%增加至72%,晶粒尺寸从29 nm增大至33 nm。随着MgO含量的增加,微晶玻璃中会析出β-石英固溶体,抗弯强度增大。