Gas Phase Catalysis by Metal Nanoparticles in Nanoporous Alumina Membranes

Nanoporous alumina membranes, loaded with palladium and ruthenium nanoparticles of various size, were used for gas phase hydrogenation of 1, 3‐butadiene and for oxidation of carbon monoxide, respectively. Those membranes contain 10⁹ ‐ 10¹¹ pores per cm², all running perpendicular to the surface. Membrane discs of 20 mm in diameter and only 60 μm thick, incorporated in a reactor in which the reactants can be pumped in a closed circuit through the pores, turned out to very actively catalyze hydrogenation of butadiene (Pd) and oxidation of CO (Ru). The activity of the Pd catalysts depends characteristically on the particles size, the gas flow, and of the educts ratio. As could be expected, larger particles are less active than smaller ones, whereas increasing gas flows in case of hydrogenation accelerates the reactions. Excessive hydrogen reduces selectivity with respect to the various butenes, but favours formation of butane.     

A comprehensive two-dimensional map of cytosolic proteins of Bacillus subtilis

Proteomics relying on two-dimensional (2-D) gel electrophoresis of proteins followed by spot identification with mass spectrometry is an excellent experimental tool for physiological studies opening a new perspective for understanding overall cell physiology. This is the intriguing outcome of a method introduced by Klose and O'Farrell independently 25 years ago. Physiological proteomics requires a 2-D reference map on which most of the main proteins were identified. In this paper, we present such a reference map with more than 300 entries for Bacillus subtilis proteins with an isoelectric point (pI) between 4 and 7. The most abundant proteins of exponentially growing cells were compiled and shown to perform mainly housekeeping functions in glycolysis, tricarboxylic acid cycle (TCC), amino acid biosynthesis and translation as well as protein quality control. Furthermore, putative post-translational modifications were shown at a large scale, with 47 proteins in total forming more than one spot. In a few selected cases evidence for phosphorylation of these proteins is presented. The proteome analysis in the standard pI range was complemented by either stretching the most crowded regions in a narrow pH gradient 4.5-5.5, or by adding other fractions of the total B. subtilis proteome such as alkaline proteins as well as extracellular proteins. A big challenge for future studies is to provide an experimental protocol covering the fraction of intrinsic membrane proteins that almost totally escaped detection by the experimental procedure used in this study.     

Zur Chemie der Pyrrolpigmente, 56. Mitt.

From an investigation of the ICD of bilatrienes-abc and 2,3-dihydrobilatrienes-abc induced by mixtures of CCl₄ with (+)-cis-Pinane, (–)-lactic and (+)-tartaric acid esters it is concluded that specific interactions between chromophore and the chiral reagents afford a partial resolution of the labile racemate of helices. Attaching chiral residues covalently to the chromophore induces very low resolution of the same kind in case of apolar ligands like a cholesteryl-residue. However, with polar ligands as in the case ofBoc-lysyl derivatives enantiomeric excesses up to 90% are achieved depending on the solvent used.

Herrn Prof. Dr.Karl Schlögl zu seinem 60. Geburtstag gewidmet.     

Phononen fn Polymeren unter Berücksichtigung von Strukturdefekten

Zusammenfassung In den Schwingungsspektren teilkristalliner Polymerer findet man Banden, die von Falten, Kinken und anderen Konformationsdefekten herrühren, die also von der physikalischen Struktur abhängen und daher in engem Zusammenhang mit Herstellungsparametern und technologischen Eigenschaften stehen. Eine Zuordnung dieser Banden ist als Hilfsmittel zur StrukturAufklärung wünschenswert. Die klassische Normalkoordinaten-Analyse ist für diese Zwecke unbrauchbar, da nicht die regelmäßig wiederkehrenden Strukturelemente, vielmehr die Strukturdefekte maßgeblich sind. Abgesehen von Modellrechnungen an kleinen Molekülen oder Kontinuumstheorien gibt es zur Zeit nur zwei praktisch erprobte Verfahren auf molekularer Basis: Eine vonZerbi und Mitarbeitern entwickelte rein numerische Methode und eine vom Verfasser und Mitarbeitern entwickelte semianalytische Methode.Die vorliegende Arbeit gibt eine erste Gesamtdarstellung der semianalytischen Methode für beliebige Polymere von atomistischen Grundlagen bis zum Defekt-Zusatzspektrum, wobei einige für praktische Rechnungen wichtige theoretische Beziehungen erstmalig hier veröffentlicht werden. Nach einer Diskussion der Vorteile des semianalytischen Verfahrens wird ein überblick über bisherige Anwendungen dieser Methode auf Polyäthylen (Skelettmodell und Schalenmodell) gegeben.

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Summary In the vibrational spectra of semicrystalline polymers there are extra peaks due to folds, kinks and other conformational defects. They depend on the physical structure in close connection to the parameters of the fabrication process as well as to technological properties. An assignment of these peaks is desirable for structure elucidation. The classical normal coordinate analysis cannot be used because of the irregularity of the defects. Aside from model calculations at small molecules and continuum theories there are essentially two practically working molecular methods: A purely numerical method, developed byZerbi and coworkers, and a semianalytical method, developed by the author and coworkers.This paper is a review of the semianalytical method for arbitrary polymers, starting from atomistic considerations and ending with the defect induced density of states. It contains some hitherto unpublished theoretical relations of importance for practical calculations. The advantages of the semianalytical method are discussed. Recent applications on polyethylene (skeletal model and shell model) are reviewed.

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Mit 2 Abbildungen und 1 Tabelle     

Synthesis and reactions of 2-(alkylthio)-4,4-dimenthyl-1,3-thiazole-5(4H)-thiones

Six 2-(alkylthio)-substituted 4,4-dimethyl-1,3-thiazole-5(4H)-thiones were synthesized according to a new method. The reactions of these compounds with allyl- and benzyllithium reagents, 1,3-dipoles, and dimethyl acetylenedicarboxylate proceeded in a similar manner to 2-alkyl-substituted analogues, while methyllithium reacted in a different way yielding trithio-orthoester derivatives.     

UV-VIS and CD-spectroscopic investigations of intermolecular interactions of bile pigments with small proteins

Summary The intermolecular complex formation of bilirubin and biliverdin with two proteins (basic pancreatic trypsin inhibitor and lysozyme) were studied by optical and chiroptical methods. Evidence for specific intermolecular interactions of biliverdin with both proteins was found. Bilirubin forms a soluble complex only with lysozyme.

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UV-VIS und CD-spektroskopische Untersuchungen intermolekularer Wechselwirkungen von Gallenpigmenten mit kleinen Proteinen

Zusammenfassung Die intermolekulare Komplexbildung von Bilirubin und Biliverdin mit zwei Proteinen (basischer pankreatischer Trypsininhibitor und Lysozym) wurden mittels optischer und chiroptischer Spektroskopie untersucht. Für Biliverdin konnten intermolekulare Wechselwirkungen mit beiden Proteinen nachgewiesen werden. Bilirubin bildet nur mit Lysozym einen löslichen Komplex.