Visible‐Light‐Induced Passerini Multicomponent Polymerization

Herein, we introduce an additive‐free visible‐light‐induced Passerini multicomponent polymerization (MCP) for the generation of high molar mass chains. In place of classical aldehydes (or ketones), highly reactive, in situ photogenerated thioaldehydes are exploited along with isocyanides and carboxylic acids. Prone to side reactions, the thioaldehyde moieties create a complex reaction environment which can be tamed by optimizing the synthetic conditions utilizing stochastic reaction path analysis, highlighting the potential of semi‐batch procedures. Once the complex MCP environment is understood, step‐growth polymers can be synthesized under mild reaction conditions which—after a Mumm rearrangement—result in the incorporation of thioester moieties directly into the polymer backbone, leading to soft matter materials that can be degraded by straightforward aminolysis or chain expanded by thiirane insertion.     

Structural,microchemical and superconducting properties of ultrathin NbN films on silicon

Structural, chemical and superconducting properties of thin NbN films used for development of fast and sensitive hot‐electron bolometer (HEB) detectors for wide spectra range are reported. The thin NbN films with a thickness between 4 and 10 nm were deposited on the (001)Si substrates by magnetron sputtering. In order to investigate the film morphology and microchemistry, diffraction‐contrast and high‐resolution transmission electron microscopy (TEM) in combination with scanning TEM and electron energy loss spectroscopy (EELS) were performed. In addition, the zero‐resistance critical temperature of the NbN films was measured and correlated to their thickness. The interrelations between fabrication conditions, crystalline and superconducting properties of the differently thick NbN films are discussed. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Fluorometric assay of lipoperoxides and chromatographic analysis of alpha-tocopherol and fatty acids as biomarkers of risk from coronary atherosclerosis

There has been growing interest in the quantitative determination of biochemical predictors of atherogenesis. The aim of the present study was to investigate association of lipoperoxidation biomarkers known to be pro-atherogenic (thiobarbituric acid reactive substance activity, TBARS) or anti-atherogenic (alpha-tocopherol) with the fatty acid status, and relate it to the coronary artery disease (CAD) as assessed by coronary angiography in patients with stable angina pectoris. We found that serum lipoproteins and TBARS did not differ significantly. However there was significant correlation of TBARS with total vitamin E (P=0.02) and vitamin E in very low-density lipoprotein (VLDL) (P=0.02) and low-density lipoprotein (LDL) (P=0.01), with LDL-linoleic acid (P=0.01), and high-density lipoprotein-linoleic acid (P=0.02). There was significant correlation of total vitamin E (P=0.01) and VLDL-vitamin E (P=0.01) with the degree of CAD. We conclude that TBARS and alpha-tocopherol could not be evaluated as biomarkers for the severity of CAD among the patients with stable angina pectoris.     

The vertical distribution of halocarbons in the stratosphere

Summary By means of cryogenic sampling and subsequent gas-chromatographic analysis vertical profiles of CCl₄, CCl₃F, CCl₂F₂, CClF₃, CF₄, C₂Cl₃F₃, C₂Cl₂F₄, C₂ClF₅, C₂F₆, CH₃Cl and CH₃CCl₃ were derived for stratospheric heights up to 35 km. Vertical profiles of halocarbons computed by means of one-dimensional and two-dimensional models fall off less rapidly in the stratosphere than the measured profiles, this systematic discrepancy being due to deficiencies in the radiation and transport schemes of present models. It is shown that measured profiles of fully halogenated hydrocarbons provide a tool for systematically studying these deficiencies and thus improving the models. Sources and sinks of halocarbons are discussed, and an assessment of past and future sources of organically bound chlorine in the atmosphere is made.

---

Die vertikale Verteilung halogenierter Kohlenwasserstoffe in der stratosphäre

Zusammenfassung Die vertikalen Profile von CCl₄, CCl₃F, CCl₂F₂, CClF₃, CF₄, C₂Cl₃F₃, C₂Cl₂F₄, C₂ClF₅, C₂F₆, CH₃Cl und CH₃CCl₃ wurden für stratosphärische Höhen bis zu 35 km mit Hilfe kryogener Probenahme und anschließender gas-chromatographischer Analyse bestimmt. Die mit Hilfe von ein- und zweidimensionalen Modellen berechneten Profile fallen in der Stratosphäre weniger schnell ab als die gemessenen. Dieser systematische Unterschied ist auf Mängel in den Strahlungs- und Transportmechanismen der gegenwärtigen Modelle zurückzuführen. Es wird gezeigt, daß die gemessenen Profile der vollhalogenisierten Kohlenwasserstoffe dazu dienen können, diese Mängel zu untersuchen und die Modelle zu verbessern. Ursprung und Verbleib der halogenierten Kohlenwasserstoffe werden beschrieben und vergangene und zukünftige Quellen organisch gebundenen Chlors in der Atmosphäre diskutiert.

     

Influences of temperature,pressure and eluent composition on the behavior of binary eluents at sub- and supercritical conditions. Pentane and diethyleneglycol dimethyl ether

Summary In supercritical fluid chromatography (SFC), studies on binary eluents composed of pentane and diethyleneglycol dimethylether were performed in the concentration rage of 5 to 15% of the ether compound and at pressures of 20 to 50 bar. Influences of temperature, pressure and eluent composition on the behavior of the mobile phase were found to closely resemble those for pentane-dioxane mixtures. Resolution depended on variations in capacity ratios, selectivities, and plate numbers. The critical data for diethyleneglycol dimethylether were estimated by means of different group contribution methods.