Linearization of column responses by correlation chromatography. Separation improvement and reduction of undesired adsorption effects

Summary Experiments and simulations prove that correlation chromatography can greatly reduce the disadvantage of a non-linear response of the chromatographic column. A factor that has been accepted as being an important source of error in correlation or multiplex chromatography, has been shown not to be. Separations affected, improve dramatically when correlation chromatography is used, and a substantial amount of correlation noise only arises when there is a large difference in separation between a conventional chromatogram and a correlogram.A model has been developed for simulating these nonlinearities. It is shown that, especially for correlation chromatography, the simulation results match the practical measurements very well.     

Modelling and design of a travelling-wave electro-optic modulator on InP

Based on a rigorous vectorial analysis, a fast travelling-wave Mach–Zehnder modulator is modelled and designed. The cross-section of the semiconductor layer stack and the lossy electrodes are carefully modelled using the method of lines in order to investigate propagation characteristics, velocity and losses. This yields an accurate microwave and optical field distribution to explain the behaviour of the component. In order to enhance the modulation efficiency, design curves are derived and the cross-sectional dimensions for minimum microwave loss are determined. The loss of the optimized modulator agrees very well with small-signal measurements up to 40 GHz and HFSS simulations. The layerstack of the fabricated device is suitable for integration with InP multi-wavelength lasers.     

The role of electronic factors in reagents in controlling thestereochemistry of arylsulfenyl chlorides addition

For a series of substituted arylsulfenyl chlorides the stereochemistry of Ad_E-reactions with a series of substituted Z- and E-β-deuterostyrenes has been elucidated. Non-stereospecific reaction was observed only for the pair 2,4-dinitrobenzenesulfenyl chloride-p-methoxystyrene; for all the other reactants the reaction proceeded in a strictly stereospecific manner.     

Polyfunctional compounds containing the 4,6-dialkoxy-7-arylthioheptene moiety as synthetically useful intermediates. The course of lewis acid-induced transformations

Data on the selectivity of the Lewis acids induced transformations of the title compounds are presented, and the routes leading to formation of products containing either cyclohexane or 1,3-diene units are described.     

Acylation of norcarane and its derivatives by pivaloyl tetrafluoroborate

Conclusions The decomposition of the complex obtained in the reaction of pivaloyl tetrafluoroborate with norcarane and its 1-methyl and 1-phenyl derivatives by water gives 1-hydroxy-3-pivaloyl derivatives of cyclohexanes and the corresponding unsaturated ketones. The hydride decomposition of the same complex leads to derivatives of 6-oxabicyclo[3.2.1]octane.For preliminary report see [1].Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2512–2518, November, 1976.     

Convergent synthesis of the tetracyclic bcde structural fragment of retigeranic acid

A two-step synthesis was proposed for the tetracyclic triquinane bis-enone from two monocyclic precursors. The bis-enone obtained is a structural fragment of retigeranic acid.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1908–1910, August, 1990.     

β-Arylthioalkylation of 2-methoxy-1,3-butadiene

The -arylthioalkylation of 2-methoxy-1,3-butadiene is regiospecific at the alkoxy-substituted C=C bond, giving 6-arylthioalk-1-en-3-ones.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2036–2040, September, 1990.