A new derivation and interpretation of Yule's ‘Characteristic’K

Zusammenfassung Die Reynoldsche Gleichung der hydrodynamischen Schmierungstheorie, unter ungefährer Berücksichtigung der Trägheit des Schmiermittels, wird für ein schiefes Gleitschuhlager im stationären Zustand angewendet, um den Einfluss der Trägheit des Schmiermittels auf die Belastungskapazität zu ermitteln. Man findet einen einfachen Zusammenhang sowohl zwischen der Trägheitswirkung und den physikalischen Eigenschaften des Schmiermittels wie den Bedingungen, welche das Arbeiten des Gleitschuhlagers spezifizieren. Man stellt fest, dass der Einfluss der Trägheit die Lastkapazität um einen Betrag erhöht, der wichtig sein kann in der laminaren Region.     

Herstellung keramischer Pulver. III [1]: Über die Struktur diamagnetischer Titan(III)-alkoxide

Inhaltsübersicht. Es wird über die Darstellung der Verbindung Ti(OCH₂CH₂OC₂H₅)₃ berichtet. Diamagnetismus und VIS-NIR-Absorptionsspektrum weisen auf eine ungewöhnliche Struktur hin. Semiempirische MO-Berechnungen (EHT) an ausgewählten Koordinationspolyedern ergeben für die Struktur eines flächenverknüpften Doppelwürfels qualitative Übereinstimmung mit den experimentellen Befunden. Preparation of Ceramic Powders. III. About the Structure of Diamagnetic Titan (III) Alkoxides The preparation of the compound Ti(OCH₂CH₂OC₂H₅)₃ is reported. Diamagnetism and absorption spectrum indicate an unusual structure. The results of semiempirical MO computations (EHT) for selected coordination polyhedra agree qualitatively with the experimental data for a double-cube structure of the compound.     

Quantum Lie Algebras, Their Existence, Uniqueness and q-Antisymmetry

Quantum Lie algebras are generalizations of Lie algebras which have the quantum parameter h built into their structure. They have been defined concretely as certain submodules of the quantized enveloping algebras . On them the quantum Lie product is given by the quantum adjoint action. Here we define for any finite-dimensional simple complex Lie algebra an abstract quantum Lie algebra independent of any concrete realization. Its h-dependent structure constants are given in terms of inverse quantum Clebsch-Gordan coefficients. We then show that all concrete quantum Lie algebras are isomorphic to an abstract quantum Lie algebra . In this way we prove two important properties of quantum Lie algebras: 1) all quantum Lie algebras associated to the same are isomorphic, 2) the quantum Lie product of any is q-antisymmetric. We also describe a construction of which establishes their existence. Received: 23 May 1996 / Accepted: 17 October 1996     

Spektroskopische Untersuchungen an organischen Carbonylverbindungen, 5. Mitt.: Zum Einfluß des π-Chromophors auf das elektronische Spektralverhalten von dimethylaminophenyl-substituierten β-Diketonen bei Kettenverlängerung und Variation der Arylsubstituenten

Summary Absorption and fluorescence data of dimethylaminophenyl-substituted -dicarbonyl compounds are discussed in dependence on the size of the -electronic system. The variation of the chain length and of the aryl moiety shows the strong influence of the intramolecular donor-acceptor properties on the deactivation processes. The stabilization of the S₁-state in polar solvents gives rise to fluorescences with large Stokes shifts.

     

Gleichgewichtsgeometrie und spektroskopische Eigenschaften des Biphenyls im S0-und S1-Zustand

Equilibrium geometry and spectroscopic properties of biphenyl in the S₀ and S₁ state Equilibrium geometries for the S₀ and S₁ state of biphenyl were determined by minimization of the total energy with respect to all cartesian coordinates. The molecule is twisted in the S₀ state (20°), but becomes planar in the S₁ state. Using these results, an interpretation of the fluorescence and absorption spectra can be given. In passing from the S₀ to the S₁ state equilibrium geometry a remarkable change of the state ordering occurs.     

Cationic and pseudocationic polymerization of aromatic olefins—III. [1a.b]: A re-investigation of the polymerization of styrene by perchloric acid in methylene dichloride

A reinvestigation of the polymerization of styrene by perchloric acid in methylene dichloride at 0° with improved techniques has shown that the polymerizations are not of first order throughout; after the first half-life, the reaction accelerates and the electrical conductivity of the reaction mixture increases concurrently. These phenomena are ascribed to the slow ionization of the propagating polystyrylperchlorate ester to much more rapidly propagating polystyryl ions present in very low concentrations, and in equilibrium with a much larger concentration of non-propagating polystyrylindanyl ions. Our observations, together with those of other authors on the bimodal DP distribution of polystyrenes formed under similar conditions, confirm that the pseudocationic polymerization propagated by the polystyryl perchlorate ester is indeed a distinct form of reaction.     

Über die Halogenide des Europiums

Monatshefte für Chemie - Chemical Monthly -