New analytical method for determination and speciation of forms of carbon

A new analytical method is presented, allowing the identification and determination of various forms of carbon (elemental and combined) present in materials. The method is based on temperature-controlled heating of the sample in oxygen or an inert atmosphere, with continuous recording of the amount of carbon oxides evolved, as a function of temperature. The application of the method is demonstrated with typical examples (cast iron, artificial diamond, carbides isolated from steel, electrographite).     

NMR study of the structure of poly(N-benzoyl-8-octanelactam)

The structure of a polymer prepared by the polymerization of N-benzoyl-8-octanelactam initiated with benzoic acid was studied by ¹H and ¹³C NMR, using S-INEPT, COSY, COLOC, and ROSEY methods, with the aid of model oligomers. Beside the expected N-benzoylated segments, the polymer also contained deacylated segments and about 50% of branching units. The polymer can be characterized as a statistical, highly branched copolymer of N-benzoyl-8-octanelactam and 8-octanelactam. © 1993 John Wiley & Sons, Inc.     

Theoretical investigation of the interaction between the hydrogen atom and Pd clusters

The chemisorption of hydrogen on small Pd_n clusters (n = 1–3) has been investigated using the pseudopotential procedure followed by configuration interaction (PP-CI). The interaction of H with the cluster modeling the three-fold hollow site of the Pd(111) surface is found to be stronger than that at the bridge and the top site models. When H occupies a top site the bonding has a partial ionic character as a consequence of charge transfer from the metal to H. At the bridge and hollow sites the bonding is essentially covalent. The MO energy spectrum of the Pd₃-H (hollow) cluster is characterized by the presence of a well separated MO level ～ 7 eV below the Fermi level which is consistent with the experimentally observed photoelectron spectra of H on Pd(111) surface. The bonding between H and Pd clusters occurs mainly via d-orbitals and seems to be of quite local nature.     

Steroidal,Aldosterone Antagonists: Increased selectivity of 9α,11-epoxy derivatives

In the search for aldosterone antagonists with an optimal activity profile, twelve 9α, 11-epoxy-steroids were prepared and compared with their 9α, 11α -unsubstituted analogues in terms of steroid receptor binding in vitro and electrolyte excretion in vivo. Substitution of the parent structures by an epoxy group at positions 9α, 11 resulted in marginal effects on mineralocorticoid receptor binding and electrolyte excretion, but greatly reduced androgen and gestagen receptor binding. This finding is reflected in the largely lacking unwanted anti-androgenic and gestagenic side effects in animal models of the three most interesting 9α, 11 -epoxy-spirolactones 4 (CGP 33033), 18 (CGP 29245), and 25 (CGP 30083).     

Linearity and Unprovability of Set Union Problem Strategies

In this paper we prove that strong postorder path compression systems have linear growth.     

Logic and Natural Selection

Is logic, feasibly, a product of natural selection? In this paper we treat this question as dependent upon the prior question of where logic is founded. After excluding other possibilities, we conclude that logic resides in our language, in the shape of inferential rules governing the logical vocabulary of the language. This means that knowledge of (the laws of) logic is inseparable from the possession of the logical constants they govern. In this sense, logic may be seen as a product of natural selection: the emergence of logic requires the development of creatures who can wield structured languages of a specific complexity, and who are capable of putting the languages to use within specific discursive practices.     

Mechanism of levulinic acid formation

Based on the intermediates revealed by ¹³C-NMR spectroscopy, the mechanism of levulinic acid ($\text{6}$) formation in acid catalysed hydrolysis of 2-hydroxymethylfurane ($\text{1}$) and 5-hydroxymethylfuran-2-carbaldehyde ($\text{14}$) is proposed.     

Oxydimetrische Bestimmung des Osmiums in alkalischem Medium

Zusammenfassung Eine Methode der oxydimetrischen Bestimmung des vierwertigen Osmiums wurde ausgearbeitet. Sie beruht auf der potentiometrischen Titration des durch Hydrolyse des Chlorokomplexes OsCl₆ ^2– entstandenen OsO₂ in alkalischem Medium mit einer Permanganatmaßlösung in Anwesenheit von Tellursäure. Der Reaktionsmechanismus wird erklärt.

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Summary A method has been worked out for the oxydimetric determination of quadrivalent osmium. It is based on the potentiometric titration of the OsO₂ resulting from the hydrolysis of the ohlorocomplex OsCl₆ ^2– in alkaline surroundings with a solution of permanganate in the presence of telluric acid. The reaction mechanism is explained.

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Résumé On a mis au point une méthode de dosage oxydimétrique de l'osmium tétravalent. Elle repose sur le titrage potentiométrique de OsO₂ prenant naissance par hydrolyse du complexe chloré OsCl₆ ^2– en milieu alcalin par une solution de permanganate en présence d'acide tellurique. On interprête le mécanisme de la réaction.

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Herrn Prof. Dr. Ing.M. Jureek zum 60. Geburtstag gewidmet.