Liquid chromatography electrospray mass spectrometry with variable fragmentor voltages gives simultaneous elemental and molecular detection of arsenic compounds

A single quadrupole high performance liquid chromatography electrospray mass spectrometry system with a variable fragmentor voltage facility was used in the positive ion mode for simultaneous recording of elemental and molecular mass spectral data for arsenic compounds. The method was applicable to the seven organoarsenic compounds tested: four arsenic-containing carbohydrates (arsenosugars), a quaternary arsonium compound (arsenobetaine), dimethylarsinic acid, and dimethylarsinoylacetic acid. It was not suitable for the two inorganic arsenic species arsenite and arsenate. In the case of arsenosugars, qualifying ion data for a characteristic common fragment (m/z 237) was also simultaneously obtained. The method was used to identify and quantify the major arsenosugars in crude extracts of two brown algae.     

Y_2O_3－Nb_2O_5－B_2O_3：Eu~（3＋）·Bi~（3＋）的燐光体的晶体结构与光谱性质

采用常规固相反应于１２００℃下制备了具有褐钇铌矿结构的Ｙ２Ｏ３·Ｎｂ２Ｏ５·Ｂ２Ｏ３（Ｙ（０．９３）Ｅｕ（０．０７））２Ｏ３·Ｎｂ２Ｏ５·Ｂ２Ｏ３和（Ｙ（０．９１）Ｅｕ（０．０７）Ｂｉ０．０２））２Ｏ３·Ｎｂ２Ｏ５·Ｂ２Ｏ３等光体，研究了它们的发光性质：结果表明，在２６８ｎｍ紫外光激发下，由于ＮｂＯ４基团于４１０ｎｍ处发生１Ｔ→１Ａ１跃迁，致使Ｙ２Ｏ５·Ｎｂ２Ｏ５·Ｂ２Ｏ３呈现更亮的紫外发射。体系中的Ｂ２Ｏ３可降低反应温度，增强ＮｂＯ４和Ｅｕ（３＋）的发光强度。（Ｙ（０．０９１）Ｅｕ（０．０７）Ｂｉ（０．０２））２Ｏ３·Ｎｂ２Ｏ５·Ｂ２Ｏ３燐光体系中所观察到的ＮｂＯ４→Ｅｕ（３＋）和Ｂｉ（３＋）→Ｅｕ（３＋）的能量传递使红光发射明显增强。     

氢气辅助的水中埋弧法制备小直径碳纳米管

用改进的石墨电弧放电方法制备了小直径、高质量的碳纳米管,以水为打弧介质,氢气为保护气体.该方法具有装置简单,电流小,无催化剂,制备出的多壁碳纳米管直径小于10 nm等优点.     

烯烃聚合数学模拟研究与现状

综述了近年来国内外在烯烃聚合微观形态和宏观反应器数学模拟方面取得的研究成果，指出了烯烃聚合过程数学模拟的发展方向。     

Reaction Ergodography and Transition State Analyses of the Addition of AIH_3 to Acetylene

The present paper covers the reaction ergodography for the addition of AlH3 to acetylene investigated by ab initio calculation with RHF/3-21G basis set. The changes in some physical properties along the reaction path (IRC) are presented. The formations of FMOs of the transition state have been analyzed according to the Fukui' s method. On the basis of the perturbation theory and Wolfsborg Helmholtz formula, we calculated the FMO' s energy orders of TS and its formation that shows the HOMO of TS consists of LUMO, HOMO of AlH3 and HOMO of HCCH.     

Procedure for background estimation in energy-dispersive X-ray fluorescence spectra

A method for semi-automatic background estimation in energy-dispersive x-ray fluorescence spectra is outlined. Two cubic splines were investigated and the spline called the Butland interpolant was chosen for further investigation. Prior to the calculation of the spline, peak regions are set up, and suitable knots are defined outside the peak regions. To set up the peak regions, an automatic peak-search routine and a calibration equation are used. For a given peak, the latter relates the full width at half maximum (FWHM) to the peak centre. In turn, the size of the peak regions are defined by the FWHM multiplied by a constant given by the user. The method was tested on several types of spectra. It was found that the optimal size of the peak region decreased with increasing peak density. Reproducibility tests showed that the standard deviation of the summation of counts within a peak region and after background subtraction was less than would be expected from the counting statistics.     

二氯亚甲基环己烷的卤化反应和2-取代二氯亚甲基环己烷的构象

多卤代烃在有机反应机理和结构研究中有着重要意义,作为一个有用的合成中间体,其制备也受到人们重视。我们在此报道二氯亚甲基环已烷(1)与氯及溴的反应和其它有关反应的实验结果。 1 于氯作用,主要得到加成产物1—氯—1—     

双核磺化酞菁铜(Ⅱ)催化氧化α-萘酚

本文研究了以乙醇为溶剂,CaCl_2为助催化剂,双核磺化酞菁铜(Ⅱ)催化氧化α-萘酚制备α-萘醌的各种因素。提出了可能的反应机理。     

Liquid-liquid Extraction System Based on Non-ionic Surfactant-salt-H_2O and Mechanism of Drug Extraction

The utilization of solid-liquid extraction system based on polymer-(NH4)2SO4 -H2O on separation of metal ions and bio-active substances has been summarized1. Cloud point extraction (CPE) benefits the environment and has been used in separation of metal chelates, biomacromolecules and in pretreatment of environmental samples2-4. In a 10 mL color comparison tube 20% PEG-1000 and 2.5 g (NH4)2SO4 were chosen as phase separation condition at pH 5.5. The average extraction efficiencies we…     

Apparent Specific Volume Measurements of Poly(ethylene oxide), Poly(butylene oxide), Poly(propylene oxide), and Octadecyl Chains in the Micellar State as a Function of Temperature

Apparent specific densities of aqueous solutions of the diblock copolymers C18(EO)100, C18(EO)20, and (EO)92(BO)18 and the triblock copolymers (EO)25(PO)40(EO)25 and (EO)21(PO)47(EO)21 in the micellar state have been measured over a temperature range from 10 to 90 degrees C at concentrations between 1% and 5%, using an oscillating tube densitometer. From these measurements, apparent specific volumes of poly(ethylene oxide) (PEO), poly(propylene oxide) (PPO), poly(butylene oxide) (PBO), and octadecane in the micellar state have been determined. The composition of the block copolymers was checked by NMR spectroscopy. Results were compared with published data for the polymers and bulk values for octadecane, respectively. The apparent specific density of PEO chains in the dissolved state was also measured for PEG4600 solutions at different concentrations and compared with results in the micellar state. The results presented in the paper are crucial in connection with analysis and modeling of small-angle X-ray scattering (SAXS) data from polymer and block copolymer micellar systems. PEO and PPO have a relatively low apparent partial specific volume in water at low temperatures. It is associated with water molecules making strong hydrogen bonds with the oxygen atoms on the polymer backbone. These water molecules gradually become disordered when the temperature is increased and the polymer apparent specific volume increases. For PBO in the micellar cores of PBO-PEO block copolymer micelles and in PNiPAM microgels, pronounced temperature dependence with the same origin is also found. The application of the derived results for the apparent specific volume of PEO for deriving contrast factors is demonstrated and the results are used in the analysis of SAXS data for semidilute solutions of PEG4600 in a broad temperature range.