纳米CeO2的表面改性及其在聚丙烯中的分散性研究

选用4种不同的偶联剂以无水乙醇为溶剂对纳米氧化铈进行表面处理,测定处理好的样品分别在环己烷中的分散性.选择经不同偶联剂处理过的样品在环己烷体系中分散效果最好的比例与聚丙烯切片共混,在扫描电镜上观察共混物断面纳米CeO2的分散情况.结果表明,表面处理有利于纳米氧化铈在聚丙烯中的分散,其中以钛酸酯3#比例为8%时处理的效果最好.钛酸酯3#处理后样品的红外光谱表明,纳米CeO2与偶联剂发生了化学键合作用,它们之间并不是简单的物理包覆.     

纳米Fe2O3/端羟基聚丁二烯(HTPB)复合粒子的制备与表征

为改善纳米Fe₂O₃在固体推进剂中的分散性, 以端羟基聚丁二烯(HTPB)和异氟尔酮二异氰酸酯(IPDI)为包覆和固化材料, 分别采用直接共混法和分步共混法制得纳米Fe₂O₃/HTPB复合粒子. 采用HRTEM, TGA, FTIR和XRD等手段表征了复合粒子的结构, 对比了复合前后纳米Fe₂O₃的分散性, 测量了HTPB包覆量和包覆层厚度. 结果表明, 这两种方法均能实现HTPB对纳米Fe₂O₃物理包覆, 但分步共混法明显优于直接共混法|在分步共混法制得的纳米Fe₂O₃/ HTPB复合粒子中, 内层的纳米Fe₂O₃分散性好, 外层HTPB厚度均一. 复合粒子亲油性结果表明, 将纳米Fe₂O₃与HTPB进行复合, 可有效改善纳米Fe₂O₃在固体推进剂中的分散性.     

表面改性对CeO2纳米粉体特性的影响

研究了表面改性对CeO2纳米粉体特性的影响，采用表面活性剂．十二烷基硫酸钠对CeO2粉末颗粒表面进行了改性。未改性和改性的纳米氧化铈用粉体综合性能测试仪、激光粒度仪、比表面积测试仪、X射线仪、扫描电子显微镜进行了表征。结果表明，用十二烷基硫酸钠表面改性能提高纳米氧化铈的流动性和分散性，减小比表面积和团聚，同时也对CeO2粉体颗粒表面改性的机制进行了探讨。     

纳米CeO2的制备及其在PMMA中的分散

制备得到一Ce-三乙醇胺(TEA)配合物,以该配合物作为制备纳米CeO2的前驱体.将甲基丙烯酸甲酯(MMA)分散于配合物水溶液中,然后在同一反应器中依次进行水解、乳液聚合反应,得到纳米CeO2分散于聚甲基丙烯酸甲酯(PMMA)基质中的复合物粉末.分别运用XRD,TEM,TGA和DSC对复合物进行了表征.结果表明,纳米CeO2粒径为3～5nm,其均匀分散于聚合物基质中且单分散性良好.聚合物的热稳定性和玻璃化温度得到提高.     

MMA接枝改性PVC/CaCO3纳米复合材料的力学性能

采用熔融共混法制备PMMA接枝改性纳米CaCO3增韧PVC（PVC/CaCO3）复合材料,并研究了复合材料的力学性能.结果表明,通过表面PMMA的接枝改性,可以显著提高纳米CaCO3增韧聚氯乙烯复合材料的拉伸强度和拉伸模量,在纳米CaCO3颗粒表面PMMA包覆层厚度为2nm时,复合材料的拉伸强度和拉伸模量达到极大值.对比于未处理纳米CaCO3和钛酸酯偶联剂处理纳米CaCO3,PMMA接枝改性纳米CaCO3增韧PVC复合材料的拉伸强度得到较大幅度提高.SEM显示,经过PMMA接枝改性后的碳酸钙在PVC基体中分散均匀,与基体界面结合良好.     

疏水上转换纳米晶的均相体系聚合物包覆及在发光检测中的应用

选用水解的十八碳烯-马来酸酐共聚物(PMAO)为表面修饰分子,发展了一种以疏水纳米粒子吸附表面活性剂十二烷基磺酸钠(Na YF_4-SDS)为中间体的均一液相聚合物包覆纳米粒子方法.该方法解决了油溶性纳米晶与弱极性聚合物分子难以在单一体系下均匀分散的问题,实现了在均一液相体系下对疏水纳米晶的单分散包覆以及表面羧酸官能团修饰.红外光谱与表面Zeta电位测试结果表明纳米晶已被聚合物包覆,粒子表面为强电负性的羧酸基团.电镜结果表明聚合物包覆的上转换纳米晶粒径无明显的变化,具有良好的单分散性.发射光谱表明聚合物包覆前后粒子的发射谱带无显著变化,保持了原油相粒子的发光性能.进一步的特异性识别荧光显微成像实验证实聚合物包覆后的粒子(Na YF_4-PMAO)可用于生物学检测.     

超声场中纳米TiO2表面包覆氧化硅的研究

在超声场中，通过硅酸钠水解生成的无定形氧化硅对金红石相纳米TiO₂进行表面包覆，利用红外光谱、X射线光电子能谱、X射线衍射和透射电镜对所得样品进行了表征，并对纳米TiO₂的光稳定性和分散性进行了评价。红外光谱和X射线光电子能谱表明，氧化硅以化学键合的方式沉积在纳米TiO₂的表面，在包覆层和纳米TiO₂颗粒之间的界面上形成了Ti-O-Si键。TEM照片、表面元素分析和光稳定性实验显示，氧化硅在纳米TiO₂表面形成了均匀的包覆层，超声场有助于提高包覆层的均匀性和致密性。氧化硅的表面包覆提高了纳米TiO₂在水中的分散性、紫外线屏蔽能力和可见光透过性。随着氧化硅含量的增加，纳米TiO₂的光稳定性逐渐提高，当m(SiO₂)∶m(TiO₂)>1∶5时，纳米TiO₂的光稳定性基本不变，而且在热处理过程中纳米TiO₂的晶粒生长得到有效抑制。     

荧光增强核壳结构NaYF_4:Yb,Er@NaGdF_4@SiO_2@Ag上转换荧光纳米粒子的制备与性能

通过热分解法合成了NaYF_4:Yb,Er油溶性上转换荧光纳米粒子,并以NaYF_4:Yb,Er为晶种制备了核壳结构的NaYF_4:Yb,Er@Na Gd F4荧光纳米粒子,经荧光测试纳米粒子的荧光性能提高了8倍。用反相微乳液法在纳米粒子表面包覆了一层Si O2-(CH2)3-NH2,有效地改善了纳米粒子的水溶性。在Si O2表面沉积Ag纳米粒子,通过贵金属纳米粒子表面等离子共振效应进一步增强了复合纳米粒子的荧光性能,经测试纳米粒子荧光性能又提高了8倍。通过小鼠体内成像实验,发现所合成的纳米粒子生物体内具有较强荧光成像功能。试验中还发现表面活性剂Igepal CO-520和TEOS对包覆层形貌有着重要的影响。     

一种复合熔融碳酸盐燃料电池基体阴极的制备和性质研究

采用电泳沉积技术将LiCoO2和CeO2两种纳米颗粒同时沉积至多孔镍基阴极表面,获得一种新型复合基体阴极材料——LiCoO2-CeO2-Ni。研究了其在模拟熔融碳酸盐燃料电池(MCFC)工作条件下的形变/溶解行为,并对其实验前后的表面进行了详细分析。结果表明,与传统多孔镍基阴极相比,新基体阴极材料在模拟MCFC启动及运行条件下形变微小,镍溶出速率低。材料表面所修饰的纳米颗粒薄层对镍基体包覆致密且与之形成稳定新相,从而有效抑制了材料的形变和溶解。     

二氧化硅/聚苯乙烯单分散性核/壳复合球的制备

采用无皂乳液聚合包覆 ,制备了二氧化硅 聚苯乙烯单分散核 壳 (SiO2 PS)复合颗粒 ,包覆层厚度达到 10 0nm .选择 80～ 2 5 0nm二氧化硅粒径作为核颗粒 .为提高包覆效率 ,二氧化硅颗粒先用偶联剂甲基丙烯酰 (3 三甲氧基硅烷 )丙酯 (MPS)进行不同程度的表面改性 .控制MPS的结合率和单体的初始浓度可提高包覆效率 ,同时得到了单分散性复合颗粒 ,用透射电镜 (TEM)观察复合粒子的核 壳形态 .用动态光散射法 (DLS)测量表明所得复合颗粒具有单分散性 .     

Dichroism of absorption and polarization of phosphorescence of molecules of the closed form of nitrobenzospirothiopyran

The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997.     

非那雄胺合成工艺改进

非那雄胺能抑制5α-还原酶的活性,明显降低二氢睾酮水平,是一种治疗良性前列腺增生的有效药品。该合成工艺以甾烯酮酸为原料,将其与氯化亚砜反应,无须分离即与叔丁胺反应得17β-酰胺化合物,再氧化开环,环合,氢化,脱氢合成了非那雄胺。经元素分析、IR、1HNMR、13CNMR、MS分析表征了其结构。该法无须使用昂贵的2,2-二吡啶二硫化物和剧毒药品苯亚硒酸酐,且以乙酸铵代替氨气,降低了对设备的要求和腐蚀,更适用于工业生产。     

Acid hydrolysis of carboxymethylcellulose of low degree of substitution

Cotton cellulose was swollen in a sodium hydroxide solution and carboxymethylated by a two-bath method for different periods of time for each process. The kinetics of acid hydrolysis and the crystallinity of the swollen and carboxymethylated samples were measured. The proportion of broken bonds, rate constants for hydrolysis, and permeability of cellulose to hydrolyzing agents were calculated. The susceptibility of glycosidic linkages to acid hydrolysis was improved by carboxymethylation more than by swelling in alkali. The increased accessibility of carboxymethylcellulose to acid was regarded as a consequence of increased intra-and intercrystalline swelling and of the glycosidic bonds' weakness caused by the electron-attracting carboxymethyl group on the C-6 position.     

恶臭嗅辨实验室建设探讨

针对恶臭测试的环境影响问题,提出了解决的实例方案,并对方案的要点及优缺点进行讨论,此方案在实际操作中具有较好的效果。     

Estimation of Kinetic Parameters of Thermal Oxidation of Ilmenite

The aim of the presented work was the investigation of thermal oxidation of ilmenite in static air atmosphere. The investigations were carried out by use of a derivatograph (MOM, Hungary). The changes of crystallographic structure of investigated samples were identified by X-ray diffractometry on Philips PW-1710 diffractometer. In temperature above 500°C appears structure of hematite Fe₂O₃. On the basis of the thermogravimetric measurements, the contracting area and contracting volume models were found as the best fitting experimental data. This revised version was published online in August 2006 with corrections to the Cover Date.     

Mechanism of action of base-catalyzed oxygenation of phenol derivatives

Cyclopropyl derivative of 2,6-di-tert-butylphenol is synthesized as a probe to investigate the mechanism of base-catalyzed autooxidation of phenol derivatives. Our study indicates that one electron reduction of molecular oxygen from phenolate gives phenoxyl radical 3, a key intermediate of autooxidation. The coupling of phenoxyl radical and superoxide radical gives peroxylate anion 4 and produces the final epoxy alcohol adduct 6.     

氯氧化镁生成热的研究

用氧化镁氯化镁水溶液制备了8水合氯氧化镁[nMg(OH)2·MgCl2·8H2O], 并测定了其在盐酸中的溶解热, 实验结果表明, 氯氧化镁溶解热与n值呈线性关系, 根据溶解热求出5Mg(OH)2·MgCl2·8H2O和3Mg(OH)2·MgCl2·8H2O的生成热分别为-7727.1和5888.1kJ·mol^1^-。     

Determination of heats of detonation and influence of components of composite explosives on heats of detonation of high explosives

The heats of detonation of 20 simple high explosives and explosive mixtures were determined by means of an adiabatic detonation calorimeter designed by the authors. The results indicated that the performance of the instrument was reliable and the experimental data were very accurate. For explosive mixtures, there was a linear accumulative relationship between the heats of detonation of the explosive mixture and its components. Accordingly, the heats of detonation of explosive mixtures could be calculated directly from the heats of detonation of simple explosives and the characteristic heats of other components. The experiments showed that the gold or brass shell of the cylindrical charge could be substituted by a thick-walled porcelain shell, which had the advantage of cheapness.

     

化学计量中不确定度评定研究进展

测量不确定度是表征合理地赋予被测量之值的分散性的参数。本文针对化学计量不确定度评定基础模型仅适用于线性模型、概率分布为正态分布或缩放位移t分布等局限,介绍了近年来不确定度评定的研究热点:蒙特卡罗方法(Monte Carlo Method,MCM),不确定度评定的来源、评定概念、评估方法及其发展过程,扩大了测量不确定度评定与表示的适用范围。     

微量钙的测定方法研究进展

介绍了1995-2006年期间测定微量和痕量钙的方法,如电感耦合等离子体-原子发射光谱法、原子吸收光谱法以及离子色谱法等的工作原理和特点,并说明了其测定微量钙的应用领域。并对微量钙的测定技术进行了展望(引用文献55篇)。