Controlled hydrothermal synthesis and structural characterization of a nickel selenide series

A series of nickel selenides (NiSe2 microcrystals, Ni(1-x)Se and Ni3Se2 microspheres) has been successfully synthesized through a convenient, low-temperature hydrothermal method. A good nucleation and growth environment has been created by forming a uniform and transparent solution reaction system. The compositions (including the x value of Ni(1-x)Se), phase structures, as well as the morphologies of nickel selenides, can be controlled by adjusting the Ni/Se ratio of the raw materials, the pH, the reaction temperatures and times, and so forth. The newly produced Se microspheres in the system have been used as both reactant and in situ template to the Ni(1-x)Se microspheres. It is found that Ni(1-x)Se microspheres act as the intermediate precursor during the formation of Ni3Se2 microspheres. Under certain conditions, hexagonal NiSe microspheres can be converted into rhombohedral NiSe nanowires in solution. The formation mechanisms of a series of nickel selenides has been investigated in detail by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses. This work has provided a general, simple, and effective method to control the composition, phase structure, and morphology of metal selenides in aqueous solution, which will be important for inorganic synthesis methodology and further applications of selenides.     

动,静态硫化（NR＋SBR）／PE共混体系的结构与性能

用TEM研究了(NR SBR)/PE共混体系经动、静态硫化后的形态结构及其与力学性能的关系。未硫化和静态硫化体系的形态结构与其组成有关,均以含量大的组份为连续相;对动态硫化体系,当(NR=SBR)/PE<70/30时,均以PE为连续相,其性能主要依赖于构成连续相组份的性质。 动态硫化体系的T_g值低于静态体系,随PE组份含量的增加变化不大,而静态硫化体系的T_g值则随PE含量增加向高温方向迁移。用DSC测得动态硫化体系的结晶度比静态体系的大。前者的应力-应变性能也低于后者。     

二价氯化稀土催化丁二烯聚合的活性

<正> 稀土催化聚合双烯烃的研究表明,不同稀土元素的催化活性极不一样,对此虽有不同的解释,但通常公认Sm、Eu等活性骤低,可归之于它们在制备催化剂过程中极易被烷基铝从三价还原到二价,又根据大部分具活性的其它稀土元素在催化体系中总是三价的事实,进而推断:只有在体系中能保持三价的稀土化合物方有产生活性的可能,二价化合物则不具活性。然而,由于二价稀土化合物,特别是除Sm、Eu之外的二价化合物难以制得,迄今为止并无直接的实验事实来判断这些推断是否正确。     

黄芪中微量锌的测定

用分光光度法测定了黄芪中锌的含量,该法的平均回收率为99.01%.变异系数为1.50%.     

CdSe/ZnS-labeled carboxymethyl chitosan as a bioprobe for live cell imaging

A simple and convenient method for the construction of CdSe/ZnS-labeled polysaccharides as bioprobes were developed, which are highly biocompatible and photostable, and have been proven to be suitable for live cell imaging.     

容量法测定氧化钒中的各种价态钒

用NaOH溶液处理样品，分离V（V）然后以Fe(Ⅱ）滴定测定之。定量加入过量的V（V）到上述残渣中并用H2SO4溶解，用Fe(Ⅱ）滴定，计算出V（Ⅱ），V（Ⅲ）的含量。V（Ⅳ）的测定是通过从总钒量中扣除V（Ⅱ）、V（Ⅲ）、V（Ⅴ）的含量得到。V（Ⅱ）、V（Ⅲ）和V（Ⅴ）的回收率均大于96％，其8次测定结果的相对标准偏差分别为：9．8％、0．4％、1．2％；本法快速、简便，在实际应用中效果良好。