The determination of chlorinated biphenyls,chlorinated dibenzodioxins,and chlorinated dibenzofurans by GC-MS

High resolution gas chromatography, with mass selective detection, has been used for the analysis of PCB on methyl 50 % octyl polysiloxane (SB 50 Octyl), methyl octadecyl polysiloxane, and a smectic polysiloxane (SB Smectic); and for the analysis of polychlorodibenzodioxins and polychlorodibenzofurans with 1 to 8 chlorine substituents on 100 % cyanopropyl siloxane (SP 2331), smectic polysiloxane (SB Smectic), a new polar stationary phase (DB-Dioxin). The analysis has also been performed by column coupling.     

Radiation: Waves or particles? A quantized approach to time

A fundamental difficulty in theoretical physics is the dual and apparently incompatible interpretations of radiation as showing both continuous and extensive wave properties but also those of discrete atomic or smaller individual particles. Some of these contradictions are outlined. The explanation offered is of a quantized nature of time; units t_o=h/m_oc² for a particle at rest, and of similar interval unit s_o when in relative motion, with conventional relativistic corrections.

For many purposes this form of quantization replaces the need for a wave concept which then appears as a mathematical approach, chosen to avoid the physical concept of an intrinsicc time for any particle, just as we have for its intrinsic mass, spin and electrical charge. t_o and s_o are directly related to its frequency, energy and mass. The uncertainty principle and interference relations follow directly from this model, without any physical wave concept.     

平台蒸发溴化铟分子吸收光谱法测定痕量溴的研究

本文对 InBr 分子吸收光谱法测定溴进行了研究。使用平台大大降低了 InO 背景吸收,使信-背比增大十倍。铟先于溴进样可提高 InBr 吸收信号。铬空心阴极灯可代替氘灯作为测定光源。方法灵敏度为8.5ng/0.0044吸收。     

Vapor pressure of R227ea + ethanol at 343.13 K by molecular simulation

A new molecular model for 1,1,1,2,3,3,3-heptafluoropropane (R227ea) was developed on the basis of quantum chemical calculations and optimized using experimental vapor pressure and bubble density data. In combination with an existing model for ethanol, a molecular model for the binary mixture R227ea + ethanol was defined, using the Lorentz–Berthelot combining rule. It was validated at 283.17 K, where, considering the statistical uncertainties, it agrees to the experimental vapor pressure. The vapor–liquid equilibrium, comprising both bubble line and dew line data, was predicted at 343.13 K by molecular simulation. The Peng–Robinson equation of state fails for this system.     

ZnCl2熔盐的分子动力学模拟

近年来，若干作者根据几种粒子间函数，对ZnCl2熔盐结构做过分子动力学模拟［1－3］其出的Zn－Cl和Cl－Cl离子间的偏径向分布函数与中子衍射实测值符合较好，但Zn－Zn离子间距以及Zn－Zn间配位数计算值多偏高．鉴于Busing势函数在多价卤化物馆盐的分子动力学计算中应用效果较好[4],我们试用Busing势函数为基础对ZnCl2熔盐结构和能量做分子动力学计算．1研究方法计算所用粒子势为Busing势函数此处，Zi为离子的电行数（ZZn。＋＝2，Zcl－＝1），几；是离子有效半径，人为＊离子的“硬度”参数·据文献问，f二0．005071，尸zn。十二0．…     

Determination of rare earth impurities in high purity uranium by isotope dilution analysis

Summary An isotope dilution method for the determination of rare earth impurities in uranium has been developed and Ce, Nd, Sm, Eu and Gd have been determined in uranium oxide samples. The method involves isotopic dilution with enriched isotopes of the rare earths being measured, followed by the separation of rare earths from uranium. A mass spectrometer with thermionic source was used to determine the relative isotopic abundances in each of these rare earths. All these five elements were analysed selectively by preferential evaporation technique. Trace concentrations down to parts per billion range can be measured with good sensitivity and accuracy.

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Bestimmung von Verunreinigungen an Seltenen Erden in hochreinem Uran durch Isotopenverdünnungsanalyse

Zusammenfassung Eine Isotopenverdünnungsmethode wurde ausgearbeitet zur Bestimmung von Ce, Nd, Sm, Eu und Gd in Uranoxidproben. Das Verfahren umfaßt isotopische Verdünnung mit angereicherten Isotopen der zu bestimmenden Elemente und nachfolgende Abtrennung der Seltenen Erden von Uran. Die relativen Isotopenhäufigkeiten wurden mit Hilfe eines Massenspektrometers mit thermischer Ionenquelle bestimmt. Alle fünf Elemente wurden durch selektive Verdampfung analysiert. Spurenkonzentrationen bis herab zum ppb-Bereich konnten mit guter Empfindlichkeit und Genauigkeit erfaßt werden.

     

An investigation of the reliability of the Galerkin-Petrov method

It is shown that the Galerkin-Petrov method if applied in a controlled way yields reliable results for excited states of the same symmetry classifications as the ground state. Computations are performed for the 2¹ S and 3¹ S states of He. The problem of optimizing nonlinear parameters of the basis functions by means of the GP method is discussed. A special optimization scheme is suggested and numerically illustrated for someS states of He.     

On the configuration interaction method for singlet states

The direct CI method, which avoids explicit calculation of the Hamiltonian matrix, is presented in a new form. The method is linked with Davidson's algorithm for iterative evaluation of the ground state eigenvector. The viability of the method is indicated by the test calculations on water which are described.     

Sterically hindered aliphatic amines in the controlled synthesis of polystyrene

The kinetic features of radical polymerization of styrene in the presence of primary and secondary aliphatic amines combined with benzoyl peroxide and the molecular-mass characteristics of the resulting polymers were studied. In the presence of peroxide initiators, aliphatic amines, as potential sources of stable aminoxyl radicals, provide the synthesis of polystyrene with a controlled molecular mass without gel effect at a relatively high rate. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 159–164, January, 2007.     

Dialkyldithiocarbamate als Reagentien zur gas-chromatographischen Bestimmung von Metallen

Zusammenfassung Kleine Mengen Ni, Cu und Zn in wäßrigen Lösungen können nach Ausschütteln ihrer Dipropyldithiocarbamatochelate gas-chromatographisch bestimmt werden. Arbeitsbedingungen für den 0,01–1 ppm-Bereich werden angegeben. Die Reproduzierbarkeit der Bestimmung wird durch Zusatz eines inneren Standards verbessert.

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Dialkyldithiocarbamates as reagents for the gas-chromatographic determination of metalsII. Determination of zinc, copper and nickel as dipropyldithiocarbamato chelates after extraction from aqueous solution

Summary Small amounts of Ni, Cu and Zn in aqueous solutions can be determined by gas chromatography after extraction of their dipropyldithiocarbamatochelates. Working details for the 0.01–1 ppm range are reported. Reproducibility is markedly improved by addition of an inner standard.

Die Untersuchungen wurden in dankenswerter Weise durch Mittel der Deutschen Forschungsgemeinschaft und des Verbands der chemischen Industrie unterstützt.