On generalized Erd?s spaces

During the last years both Erd?s space and complete Erd?s space were topologically characterized by Dijkstra and van Mill. Applications include results about Erd?s type spaces in ?p-spaces as well as results about Polishable ideals on ω. We present an unifying theorem in terms of sets with a reflexive relation that among other things contains these apparently dissimilar results as special cases.     

Enantioseparations of non-benzenoid and oligo-Tröger’s bases by HPLC on Whelk O1 column

The separation of enantiomers of several ‘bis- and tris-Tröger’s bases’ by HPLC on commercially available chiral stationary phase Whelk O1 is described for the first time. The observed structure–enantioselectivity relationships are in agreement with the previously established molecular recognition model. For all ‘bis- and tris-Tröger’s bases’ studied, satisfactory to excellent enantioselectivities were observed.     

Elution order in liquid chromatography on cyclodextrin phases. Dependence on the amount of organic modifier in the eluent

Summary The composition of the eluent system in some instances determines the resolution and elution order of solutes in the reversed-phase chromatographic separation on cyclodextrin stationary phases. Both the identity and the concentration of the organic modifier can play a large role. The effect is particularly pronounced with naphthalene and its methyl derivatives with alcohol eluents.

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Elutionsfolge bei der Flüssig-Chromatographie auf Cyclodextrinphasen. Abhängigkeit vom Gehalt an organischem Modifier im Eluenten

     

The kinetics of successive addition of oxirane to alkanethiols in the presence of basic catalysts

Rate constants and activation parameters of direct reaction of oxirane with certain alkyl-2-hydroxyethyl sulfides and/or successive oxyethylene adducts in the presence of basic catalyst were studied at temperatures 323–353 K. The reactions were found to be of the first order with respect to oxirane, sulfide, and catalyst concentrations. The kinetics are consistent with a termolecular mechanism.     

Selective pressurized liquid extraction of polychlorinated biphenyls in sediment.

A selective pressurized liquid extraction procedure (SPLE) was developed for a fast determination of polychlorinated biphenyls in sediment. The final method was performed at 100 degrees C with heptane/dichloromethane (90:10, v/v) as extraction solvent for 2x5 min. Sulfuric acid impregnated silica was placed downstream of the sample in the extraction cell to remove interfering components. This simultaneous extraction/clean-up was performed in 20 min, with an average congener recovery of 92% compared to a classical 24 h Soxhlet methodology and 2 h of external manual clean-up.     

The effect of Co(II)‐mediated catalytic chain transfer on the emulsion polymerization kinetics of methyl methacrylate

The effect the catalytic chain transfer agent, bis[(difluoroboryl) dimethylglyoximato] cobalt(II) (COBF), on the course of the ab initio emulsion polymerization of methyl methacrylate, and the product properties in terms of the molecular weight distribution were investigated. The emulsion polymerization kinetics have been studied with varying surfactant, initiator, and COBF concentrations. The experimentally determined average number of radicals per particle strongly depends on the concentration of COBF and proves to be in good agreement with the results of model calculations. The apparent chain transfer constant, determined up to high conversion, is in excellent agreement with the predicted value based on a mathematical model based on COBF partitioning and the Mayo equation. The results of this work enhance the fundamental understanding of the influence a catalytic chain transfer agent has on the course of the emulsion polymerization and the control of the molecular weight distribution. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5078–5089, 2009     

Membrangleichgewichte und Harmonien

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