Physical properties from association models

Equation of state models with a ‘chemical’ contribution that accounts for association and solvation effects, are computationally intensive as they have to solve an internal chemical equilibrium calculation.

Frequently, only the final results of this internal calculation are used in the subsequent evaluation of physical properties from the model. As a consequence, a substantial amount of unneeded work is performed. We show here how the state function minimization in the chemical equilibrium calculation can be utilized to simplify the calculation of physical properties like pressure and chemical potentials and the derivatives of these properties with respect to temperature, volume and composition.     

原子吸收光谱法间接测煤中形态硫

利用 SO2 -4 在 Ba Cr O4溶液中 ,可定量置换出 Cr O2 -4 ,进行原子吸收光谱法测铬 ,间接测定煤中形态硫的研究。方法较现行使用的重量法简便、快速 ,干扰少 ,硫含量在 1× 1 0 - 4 ～ 3× 1 0 - 3mg·ml- 1 呈良好线性关系。用于样品分析 ,结果满意。     

Instrument for generation of volatile organic compounds for the development of chemical sensors and evaluation of tube-type diffusive sampling

An automatic calibration apparatus for the dynamic generation of organic vapours was developed. The accurately controlled stream of nitrogen was drawn at a low flow-rate through a thermostated container filled with the standard substance, thus generating a continuous stream of saturated vapour of the compound. The compound holder vessel was thermostated at −16°C. A large stream of pure carrier gas was mixed with a low stream of substance in a mixing chamber for dilution. The fittings were manufactured from PTFE, and tubes were made of special PTFE with an inert inner surface to eliminate the wall adsorption and to decrease the cross-diffusion. Moisture interferences were reduced using a Nafion membrane filter. The vapour generator was validated by diffusive sampling and gas chromatographic methods. Standard mixtures have been prepared containing toluene at concentrations ranging from 3 to 3000 ppm. The combined uncertainty of preparative and analytical error components associated with the concentration of the analytes at the 95% confidence level typically ranges from 2 to 5% relative, depending upon the concentration. The measured and the calculated values were compared and good correlation (r²>0.99) was found.     

Chemical bonding and optical properties of germanium–carbon alloy films prepared by magnetron co-sputtering as a function of substrate temperature

Amorphous non-hydrogenated germanium carbide (a-Ge_{1 − x}C_x) films have been prepared by magnetron co-sputtering system designed by ourselves. The chemical bonding and microstructure have been analyzed using X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. The optical properties of the films have been investigated by means of spectroscopic ellipsometry. The relationship between the chemical bonding and the optical properties has been explored. It has been found that all films with the constant carbon content are amorphous. The sp² CC and sp³ GeC bonds increase with T_s, and some sp² CC bonds gain infrared activity. The fraction of sp³ GeC bonds rises with T_s, but the fraction of sp³ GeGe bonds gradually drops down. In addition, the refractive index and extinction coefficient increase with T_s. The film optical gap is seen to reach 1.15 eV when T_s is 200 °C. However, the optical properties of a-Ge_{1 − x}C_x films almost remain stable with the substrate temperature.     

银黄口服液的质量控制及其高效液相色谱指纹图谱的研究

利用高效液相色谱方法,建立了复方银黄口服液及其原料药材黄芩和金银花的指纹图谱,测定了银黄口服液中黄芩苷 和绿原酸的含量。以Lichrospher C18色谱柱(250 mm×4.6 mm i.d.,5 μm)为分离柱,以甲醇和0.1%磷酸水溶液为流动 相进行二元梯度洗脱,流速0. 6 mL/min,在254 nm波长下检测。采用夹角余弦和相关系数的方法,计算6批银黄口服液指 纹图谱的相似度均在0.99以上,表明银黄口服液的质量未见显著差异。将银黄口服液指纹图谱中的共有峰与原料药材黄芩 和金银花的指纹图谱中的共有峰相比较,对其归属进行确认,大部分共有峰可以匹配。     

Determination of 6-Mercaptopurine in Rat Blood by Microdialysis Coupled with High Performance Liquid Chromatography on a Functionalized Multi-wall Carbon Nanotubes Modified Electrode

Introduction Sincecarbonnanotubeswerediscoveredin 1991,theyhaveattractedmuchattentionbecause oftheirremarkablenanostructureswithhighsur- facearea,highelectricalconductivity,goodchemi- calstabilityandsignificantmechanicalstrength[1]. Reportshavealreadybeenpublishedonthecata- lyst[2],nanoscaleelectronicandmechanicalsys- tems[3],andscannedprobemicroscopesandelec- tronfieldemissiontips[4].Itwasreportedthatcar- bonnanotubescouldbemadeintocarbonnan- otubeselectrodesandhavebeensuccessfullyused intheo…     

苯与铂化学吸附作用及其溶剂效应的量子化学研究

The chemical adsorption of Benzene on Pt under the effect of water has been full optimally computed with density functional B3LYP/LanL2DZ from Gaussian 98(A.9 version). The result showed the adsorption of benzene on Pt is a spontaneous process. The adsorption energies are -149.6535 and -202.1635 kJ/mol respectively in two cases, without water and in water. The adsorption energy is decreased in water solvent and the effect of water solvent is shown. The transition state of the transfer Pt on benzene was found by QST2 computation, and corresponding transfer active energies are 61.2537 and 70.8356 kJ/mol without water and in water respectively.     

具有油水分配系数测算功能的中药指纹图谱

建立了一种能同时测算中药中主要成分的油水分配系数Pow的功能化中药指纹图谱。采用微乳液电动色谱,以中药女贞子为例,对运行缓冲液浓度、pH值、十二烷基硫酸钠浓度等参数进行了优化。利用SPSS程序对磺胺等从女贞子中提取的6种标准化合物组分的迁移时间tm与其log Pow文献值进行非线性拟合,得到女贞子提取组分的标准方程线性关系良好（r=0.9880）。在相同的实验条件下测得化合物的log Pow与文献报道值较好的符合,证明该方法可靠。获得了能代表组分疏水化学特征的中药指纹图谱,测得女贞子的主要有效成分齐墩果酸的log Pow为3.63。该指纹图谱较为可靠地提供了女贞子中各种成分的log Pow,直观地反映出各组分油水分配性质的分布,对中药有效成分提取溶剂的选择、剂型的设计及制剂工艺的改进具有指导意义。     

宽叶秦岭藤根部的化学成分

通过正相和反相硅胶柱层析从宽叶秦岭藤根部乙醇提取物中分离纯化得到19个化合物,经波谱分析并结合化学方法鉴定了其结构,其中4个为新化合物,它们分别是3,5-二羟基二十烷酸羽扇豆醇酯(3),2-羟甲基-5-甲氧基苯基-O-β-D-吡喃葡萄糖甙(11),Δ5-孕甾烯-3β,20(S)-二醇-20-O-β-D-吡喃葡萄糖基(1→6)-β-D-吡喃葡萄糖甙(18,秦岭藤甙C)和Δ5-孕甾烯-3β,20(S)-二醇-3-O-β-D-吡喃葡萄糖基-20-O-β-D-吡喃葡萄糖基(1→6)-β-D-吡喃葡萄糖甙(19,秦岭藤甙D).