LiMn2O4的湿法合成及锰的光度法测定研究

The LiMn₂O₄ spinel was prepared by wet method using Li₂CO₃， Mn(CH₃COO)₂·4H₂O and CO₂ as raw ma-terials. The products were measured by TG/DTA， XRD， IR. The results Showed that the sample calcined at 800℃ for 10h was well crystallized monophase product. The contents of Mn(Ⅲ) and Mn(Ⅳ) of LiMn₂O₄ spinel were determined simultaneously by spectrophotometric analysis with pyrophosphoric acid.     

Detection of single nucleotide polymorphisms using electrospray ionization mass spectrometry: validation of a one-well assay and quantitative pooling studies

Single nucleotide polymorphisms (SNPs) are currently being mapped and databased at a remarkable pace, providing a viable means for understanding disease susceptibility, differential drug response and human evolution. Consequently, there is an increasing demand for SNP genotyping technologies that are simple, rapid, cost effective and readily amenable to automation for high-throughput analyses. In this study, we improved the Survivor Assay, a SNP detection method based on electrospray ionization mass spectrometry (ESI-MS), with several developments. One improvement is the development of a one-well assay, requiring no off-line purification of the polymerase chain reaction product, achieved by simple addition of reagent solution into a single well. Another is the on-line separation of magnesium and dideoxynucleotides using an in-house made monolithic metal chelating column, eliminating any off-line sample preparation prior to mass spectrometric analysis. Here the Survivor Assay is extended from a proof-of-principle concept to a validated method by genotyping six SNPs from five different regions of human genomic DNA in 55 individual samples with 100% accuracy. This improved Survivor Assay eliminates the tedious and time-consuming steps of sample preparation, minimizes sample handing and offers a high-throughput analysis of SNPs by ESI-MS. The current combined preparation and analysis time is 2 min per sample. The simplicity of this method has potential for full automation and parallel chromatography and, thus, reduced analysis time. In addition, we have adapted the Survivor Assay for quantitative SNP analysis in pooled DNA samples. The capabilities and sensitivity of this approach were evaluated. We demonstrate that an allele occurring at a frequency of 2% can consistently be quantitated.     

Metal Oxide Thin Films Containing Au Nano-Particles Prepared with Gas Diffusion Method

Au particles dispersed thin metal oxide films were prepared from precursor films containing HAuCl₄ with H₂S gas diffusion method. HAuCl₄ was uniformly dissolved in the films as promoted by hydroxypropyl cellulose (HPC). The mechanism of the Au particle formation was studied. It was found that HAuCl₄ was converted directly to Au metal particles upon contacting with H₂S gas. Au particles generated by this method were characterized with small particle size, sharp size distribution and high volume fraction in the films. The surface plasma resonance absorption of Au particles shifted to longer wavelength when TiO₂ component was introduced in the matrix.     

Calculation of the proton affinities of polyfluorobenzenes and the activation energies for 1,2-hydrogen shifts in their carbocations

Isolated polyfluorobenzene (PFB) molecules and their protonated forms are investigated by the AM1 method with full geometry optimization. The proton affinities of PFB are estimated for different protonated positions. The proton affinity of PFB averaged over all isomers is shown to decrease monotonically as the number of fluorine atoms in the molecule increases. The relative populations of different isomers of arenonium ions (AI) formed by PFB protonation are determined. From the calculated data, the value of ⁺ for the F atom in theipso-position is estimated as 1.00. The activation energies of the 1,2-hydrogen shifts in AI are calculated. The dependences of the proton affinity and the activation energies of 1,2-hydrogen shifts on the number of halogen atoms are found to have distinct characters for PFB and polychlorobenzenes. The physical reasons for these difference are discussed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1878–1882, November, 1993.     

铬天青S共振光散射法测定脱氧核糖核酸

介绍在阳离子表面活性剂十六烷基三甲基溴化铵(CTMAB)存在下阴离子染料铬天青S(CAS)共振光散射(RLS)法测定脱氧核糖核酸(DNA)的方法。在pH=5．27的六次甲基四铵一盐酸缓冲溶液中，研究了CAS—CT-MAB—yDNA体系的RLS光谱特征、影响因素和最佳反应条件。在最佳条件下，体系的RLS强度增加值△I与yDNA的浓度在50～800μg／L和1000～2000μg／L呈线性关系，其线性回归方程分别为△I=0．48c 2．56和△I=0．14c 17．86，相关系数分别为0．9997和0．9991，检出限为4．3ng／mL。该方法简便、快速，应用于合成样品中yDNA的测定，测定结果的相对标准偏差为2．93％～4．71％，回收率为97．8％～105．2％。     

取代苯体系的二阶非线性光学性质:动力学李代数方法

提出了一种动力学李代数方法来研究取代苯体系的非线性光学性质. 对于给定的PPP模型(Pariser-Parr-Pople)哈密顿量, 生成了一个动力学李代数. 依据这些代数元构造出演化算子作为群参数的函数, 通过求解一组非线性微分方程能够得到这些群参数. 再按照统计力学中的密度算子公式给出取代苯分子体系偶极矩的统计平均值. 于是导出二阶极化率的表达式. 与其他量子力学计算结果比较, 表明这种动力学李代数方法在预言有机共轭分子的非线性光学性质上同样有用.     

Dynamic Lie algebraic formulation of second‐order optical nonlinearity for substituted benzenes

A dynamic Lie algebraic (DLA) formulation is applied to the study of nonlinear optical properties of the substituted benzenes. We have described the generation of the dynamic Lie algebra for the model Hamiltonian used in the present study. In terms of these elements of the dynamic algebra we express the evolution operator as a function of the group parameters, which can be determined by means of solving a system of coupled nonlinear differential equations. Thus, in terms of the density matrix operator formalism in statistical mechanics we obtain the statistical averages of the electric polarization and then derive readily an expression for the hyperpolarizability of the paradisubstituted benzenes. Comparisons with experimental observations and other quantum calculations of the hyperpolarizabilities for the paradisubstituted benzenes are made qualitatively and quantitatively. These results imply that the DLA method appears useful in describing the nonlinear optical phenomena in the substituted benzene molecules. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem 93: 335–343, 2003     

微型柱在线分离-ICP-MS法测定高纯氧化铕中的14个稀土杂质

研究了微型柱在线分离-电感耦合等离子质谱法（ICP-MS）测定高纯Eu2O3中痕量Tm的方法，研制了Cyanex272负载树脂微型分离柱，优化了分离Eu2O3基体的实验条件，在线分离测定时间为25min。建立了在线柱分离测定Tm，内标补偿法直接测定其余稀土杂质的高纯Eu2O3中14个稀土杂质的ICP-MS分析方法。方法检出限为0.01μg/g-0.15μg/g，加标回收率为91.5%-110%,相对标准偏差为1.7%-4.9%。可满足快速测定99.999%Eu2O3中14个稀土杂质的要求。     

二溴羟基苯基荧光酮—乳化剂OP荧光熄灭法测定微量铬（Ⅵ）

本文基于Ｃｒ（Ⅵ）－二溴羟基苯基荧光酮（ＤＢＨ－ＰＦ）－ＯＰ体系的荧光熄灭效应，提出一种测定痕量铬（Ⅵ）的新荧光方法。在ｐＨ２．４－４．１的ＨＣｌ－ＮａＡｃ缓冲介质和ＯＰ存在下，Ｃｒ（Ⅵ）与ＤＢＨ－ＰＦ形成１：２的橙红色络合物，络合物的最大激发发工和发射波长分别是３６５ｍｍ和５２８ｎｍ。铬（Ⅵ）量在０．０５－１．５μｇ／２５ｍｌ范围内与△Ｆ呈线性关系，检测限是２．０ｎｇ／ｍｌ。方法用于电镀废液，废     

混合模式硅胶基质毛细管电色谱整体柱的制备及其电色谱性能研究

采用温和条件下的溶胶-凝胶技术，成功制备了阴离子交换-反相混合模式硅胶基质毛细管电色谱整体柱。通过调整反应液中不同前体的比例，优化了整体柱的制备条件。通过扫瞄电镜，对柱床进行了表征和分析。实验发现，所制备的整体柱电渗流的方向和大小可随流动相pH值的改变而改变，在酸性和中性条件下，具有从阴极流向阳极的电渗流；当流动相pH值升至约7．5时，电渗流方向发生了反转（由阳极流向阴极）。在优化的实验条件下，用所制备的整体柱对所考察的酸性（中性）化合物实现了快速分离，并获得了高达160，000N／m的柱效。