Fingerprint quality control of Tianjihuang by high-performance liquid chromatography-photodiode array detection

A novel, simple and accurate fingerprint method was developed using high-performance liquid chromatography-photodiode array detection (HPLC-DAD) for the quality control of Hypericum japonicum thunb (Tianjihuang), a Chinese herbal medicine used for the treatment of several bacterial diseases, infectious hepatitis, gastrointestinal disorder, internal hemorrhage and tumors. For the first time, the feasibility and advantages of employing chromatographic fingerprint were investigated and demonstrated for the evaluation of Tianjihuang by systematically comparing chromatograms with a professional analytical software recommended by State Food and Drug Administration (SFDA). Our results revealed that the chromatographic fingerprint combining similarity evaluation could efficiently identify and distinguish raw herbs of Tianjihuang from different sources. The effects resulted from collecting locations, harvesting time and storage time on herbal chromatographic fingerprints were also examined.     

Development and certification of a coal fly ash certified reference material for selected polycyclic aromatic hydrocarbons

The development and certification of a coal fly ash certified reference material (CRM) for polycyclic aromatic hydrocarbons (PAH) is described; this is the first natural matrix CRM for organic environmental analysis in China. The homogeneity and stability of this material have been tested by HPLC. The concentrations of several PAH were determined by use of two independent, different methods--solvent extraction-HPLC analysis with UV detection coupled with fluorescence detection (FLD) and solvent extraction, isolation with a silica column, and GC analysis with flame ionization detection (FID). Five certified values were determined: phenanthrene 7.1 +/- 2.6 microg g(-1), anthracene 2.0 +/- 0.8 microg g(-1), fluoranthene 7.4 +/- 1.9 microg g(-1), pyrene 7 +/- 2 microg g(-1), and benzo[a]pyrene 1.3 +/- 0.3 microg g(-1). Reference values for several other PAH are also suggested.     

Influences of permeation of vanadium ions through PVDF-g-PSSA membranes on performances of vanadium redox flow batteries

The preparation and physical characterization of a poly(vinylidene fluoride)-graft-poly(styrene sulfonic acid) (PVDF-g-PSSA) membrane prepared by a solution-grafting method were described. These membranes exhibited high conductivity with a value 3.22 x 10(-2) S/cm at 30 degrees C. ICP studies revealed that the PVDF-g-PSSA membrane showed dramatically lower vanadium ion permeability compared to Nafion 117. Trivalent vanadium ions had the highest permeability through all these membranes in contrast to pentavalent vanadium ions with the lowest. The VRB with the low-cost PVDF-g-PSSA membrane exhibited a higher performance than that with Nafion 117 under the same operating conditions, and its energy efficiency reached 75.8% at 30 mA/cm(2). The performance of VRB with the PVDF-g-PSSA membrane can be maintained after more than 200 cycles at a current density of 60 mA/cm(2).     

光谱电化学法研究亚甲基蓝的电还原反应

用极谱法研究亚甲基蓝(MB)的电极吸附过程早有报道.近几年,用光谱电化学法研究其电化学行为又引起了许多人的兴趣.但在光透薄层电极上,由于光程太短,测试溶液浓度较高,导致亚甲基蓝发生聚合,影响实验结果的准确测定.为此本文利用特制的比色皿型长光程薄层光谱电化学池,在低浓度条件下研究其在SnO_2镀膜玻璃电极上的电还原反应.     

Preparation and Characterization of Three-dimensionally Ordered Crystalline Macroporous CeO2

Three-dimensional ordered macroporous (3DOM) materials are of great potential importance in catalysis, selective separation, sensor arrays and communications with optical band gaps1. Many results in the synthesis of 3DOM materials have been reported, such as closed-packed silica spheres or polystyrenes (PS) templating routes for silica2, metal oxides1-6 and metals7. Recently, poly(methyl methacrylate) (PMMA) colloidal crystal templates have been used to prepare 3DOM materials of metals8,…     

连接基团链长度对季铵盐二聚表面活性剂C12-s-C12·2Br在水溶液中胶团化行为的影响

用电导法、稳态荧光法和粘度法研究了二聚表面活性剂C12-s-C12*2Br分子中的连接基团链长度(s=2, 3, 4, 6)对其在水溶液中聚集行为的影响. 实验发现, C12-s-C12*2Br的胶团生成能力远比其单体C12TABr强得多, 前者cmc值较后者降低一个数量级. 胶团聚集数N随表面活性剂浓度c的增大而增大, 其中当s=2时的N值在c=7.7 mmol/L后开始急剧增大. 计算结果表明, 此时胶团形状发生了明显变化, 形成了椭球形的胶团. 粘度测定结果也证实了这一点.     

Investigation on solvent casting films of surfactant-encapsulated clusters

The surfactant-encapsulated cluster (SEC) composed of a hydrophobic dimethyl dioctadecyl ammonium (DODA) shell and an encapsulated hydrophilic polyoxoanion core can form casting films. The structure of the casting film is influenced by evaporation rates of organic solvent. When the casting films are prepared by slow evaporation of chloroform, the alkyl chains are considered to possess a partial interdigitation, and the interdigitated length is 1.6 nm. The casting film structure is characterized by scanning force microscopy (SFM), Fourier transformation infrared (FT-IR), wide-angle X-ray diffraction, and differential scanning calorimetry (DSC).     

STM study on quinacridone derivative assemblies: modulation of the two-dimensional structure by coadsorption with dicarboxylic acids

We describe the two-dimensional (2D) assemblies of N,N'-dialkyl-substituted quinacridone derivatives on highly orientated pyrolytic graphite observed by scanning tunneling microscopy, and focus our discussion on whether the supramolecular organization can be modulated by the coadsorption of dicarboxylic acids. Our experiments have demonstrated that the quinacridone derivatives can form different 2D nanostructures when coadsorbed with dicarboxylic acids of different length at the liquid/graphite interface. Interestingly, N,N'-dihexadecyl-substituted quinacridone derivative alternately takes two different conformations in two columns for its coadsorption with pentadecanedioic acid and form a gridlike structure. It is shown that a cooperative effect of different interactions can be modulated by introducing guest molecule, leading to formation of different self-assembled nanostructures.     

Zn-Al-Ce三元类水滑石的制备及性质研究

采用共沉淀法，水热合成层状化合物一硝酸根柱撑锌铝铈三元类水滑石，分别测定了各种单一金属盐溶液及M^2 ／M^3 摩尔比为2，Ce^3 ／Al^3 摩尔比为0．25的混合金属盐的NaOH滴定曲线，并利用XRD对不同条件下合成产物进行物相分析。实验结果表明：在M^2 ／M^2 =2，Ce^3 ／Al^3 =0．07～0．50，pH=5．8～6．5条件下进行多种离子共沉淀，并经120℃、6h水热处理后，均能合成结构单一的ZnAlCe—HTLLcs，利用TG—DTlA、FT—IR、ICP对合成物进行了表征，筛选出适宜的合成条件，并对HTLcs层状结构的热行为进行初步研究，结果表明ZnAlCe—HTLcs热稳定性较差，层间结合水、层板羟基及层间客体物种(NO3^-)失去温度在240℃左右，易于转化为复合氧化物，将此复合氧化物应用于NO的催化?肖除反应，680℃下NO的转化率高达近100％。     

玉米叶片残体腐解过程的傅里叶变换红外光谱研究

采用傅里叶变换红外光谱对玉米植株叶片残体腐解过程进行了研究。结果表明，随着玉米叶片残体腐解的进行，羟基，酮碳基，甲基，在和次甲基的含量逐渐降收据 的含量增加。