Disordered charge distributions and dielectric loss in extra dense flint glasses

The complex permittivities of some extra dense flint glasses (EDF glasses) have been studied. The dielectric features of the samples are dominated by their PbO content. Both refractive indices and dielectric losses exhibit a close relation to the concentration of Pb ions. The latter are located either at sites of the network atoms or filling the potential minima interstitially. They can be identified by their different relaxation mechanisms. The dispersion in the submillimeter wave and FIR area is characterized by a very broad distribution of comparably sharp resonant states. Thermal lens — or hysteresis effects can be excluded.     

Large deviation estimates for a conditional probability distribution. Applications to random interaction Gibbs measures

Summary Let (X _i ,Y _i ) ^d , be independent identically distributed random variables with arbitrary distribution. We show that, for almost every(Y _i ) _i , the conditional law of the empirical field given(Y _i ) _i satisfies to large deviation inequalities. This applies to the study of Gibbs measures with random interaction, in the case of some mean-field models as well as of short range summable interaction. We show that the pressure is nonrandom, and is given by a variational formula. These random Gibbs measures have the same large deviation rate, which does not depend on the particular realization of the interaction; their local behaviour is described in terms of conditional probabilities given the interaction of solutions to the variational formula.     

Crystal structure oftrans-[PtCl2(Me2PhP)(cis-2,5-dimethylpyrrolidine)]

The complextrans-[PtCl₂ (Me₂PhP)(cis-2,4-dimethylpyrrolidine)] has been characterized by X-ray crystallography. It crystallizes in the monoclinic space group P 2₂/c witha=8.762(3),b=16.034(5),c=12.600(4)Å,=93.43(3)° andZ=4. The structure was solved by heavy atom method and refined toR=0.052 for 3251 observed counter reflections. The coordination sphere of the Pt atom is square-planar with a geometry very similar to that of the studied complexes of the type trans-[PtCl₂(R₃P)L] whereL is either one of the possible isomers of theC,C-dimethylpyrrolidine or the unsubstituted pyrrolidine. In the present complex the puckered five-membered ring of the dimethylpyrrolidine ligand assumes an envelope conformation with the maximum puckering at the N atom.     

Forces of a fluid in a rotating straight pipe

The fluid flow through a rotating straight pipe is considered, the axis of rotation being perpendicular to the pipe axis. The flow of the fluid is taken as fully developed, i.e. the velocity field is assumed to be the same in all transverse cross sections of the pipe. The derivation presented applies to viscous and nonviscous incompressible fluids. For constant angular pipe velocity a simple and exact (Coriolis type) relationF=2Q(t) is derived between the forceF by which the fluid acts on the (unit length of the) pipe in the direction perpendicular to the two axes, the fluid mass flow rateQ(t) through the pipe, and the angular velocity. Variable angular velocities, i.e. , introduce an additional term into the expression for the inertial forceF, which depends only on and on known (constant) parameters; this term is known for given angular velocity(t). The flow configuration investigated here is an idealization of those appearing (over short space and time intervals) in the devices measuring mass flow rateQ(t) through the (Coriolis) forceF. Therefore the exact results derived here cast some light on the degree of precision one expects in these devices, where more complicated flow configurations are present than those looked at in this paper.     

Superbranching processes and projections of random Cantor sets

We study sequences (X ₀, X ₁, ...) of random variables, taking values in the positive integers, which grow faster than branching processes in the sense that , for m, n0, where the X _n (m, i) are distributed as X _n and have certain properties of independence. We prove that, under appropriate conditions, X _n ^1/n almost surely and in L ¹, where =sup E(X _n )^1/n . Our principal application of this result is to study the Lebesgue measure and (Hausdorff) dimension of certain projections of sets in a class of random Cantor sets, being those obtained by repeated random subdivisions of the M-adic subcubes of [0, 1] ^d . We establish a necessary and sufficient condition for the Lebesgue measure of a projection of such a random set to be non-zero, and determine the box dimension of this projection.Work done partly whilst visiting Cornell University with the aid of a Fulbright travel grant     

Pseudo-cross-conjugated mesomeric betaines. 1. Synthesis of pseudo-cross-conjugated mesomeric betaines from quinoxaline derivatives

A new method for the synthesis of pseudo-cross-conjugated mesomeric betainic heterocyclic compounds with an angular nitrogen atom has been developed consisting in the reaction of 1,4-dielectrophile — -carbethoxy-2-(3-chloro)quinoxalylacetonitrile with azoles. Experimental regularities have been studied and a reaction mechanism has been proposed including the stage of formation of an ylide from a quaternary azolium salt. A pseudo-crossconjugated mesomeric betainic heterocyclic compound containing a thiazole ring compound has been synthesized for the first time.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1528–1533, November, 1992.     

Relativistic correction to the triton binding energy in the framework of relativistic Hamiltonian dynamics

The relativistic correction to the triton binding energy approximated to the order (v/c)² is calculated in the framework of relativistic Hamiltonian dynamics. We discuss the generator representation of the Poincaré group for three relativistic particles and its connection with the Feynman diagrams in the infinite-momentum frame (the light-front dynamics). The relativistic correction enhances the attraction in the three-nucleon system. The five-channel calculation with the Reid soft-core potential yeilds the result =–0.54 MeV, which is governed mainly by theD-wave contribution. TheS-wave contributions to are only –0.10 MeV.     

Einwirkung von Schwefel und Ammoniak auf Methyl-neopentylketon

Zusammenfassung Bei der Einwirkung von Schwefel und Ammoniak auf Methylneopentylketon in Pyridin bei Raumtemp. bilden sich die beiden theoretisch möglichen Thiazoline-³, das 2,4-Dimethyl-2-neopentyl-5-tert. butyl-thiazolin-³ und das 2-Methyl-2,4-di-neopentyl-thiazolin-³ (etwa im Verhältnis 793). Daneben entsteht 2-Methyl-2,4-dineopentyl-imidazolin-³. Die Darstellung und Charakterisierung der sich vom Methylneopentylketon ableitenden reinen isomeren -Brom- bzw. -Mercaptoketone sowie einiger daraus synthetisierter Thiazoline-³ bzw. Thiazole wird beschrieben.Für Korrespondenz ist diese Adresse zu verwenden.49. Mitt.:F. Asinger, W. Schäfer undA. Saus, Mh. Chem.96, 1278 (1965).Teil der DissertationF. Gentz, Techn. Univ. Dresden 1963.     

Quantum dynamics of H2 formation on a graphite surface through the Langmuir Hinshelwood mechanism

We have studied the formation of the H2 molecule on a graphite surface, when both H atoms are initially physisorbed. The graphite surface is assumed to be planar, and a model potential is obtained in a semiempirical way to reproduce the experimental properties of H physisorption on graphite. The reaction probability has been computed in the case when the angular momentum of the relative H-H motion lies parallel to the surface plane. Three-dimensional wave packet calculations have been performed for collision energies ranging from 2 to 50 meV. It is shown that the reaction occurs with a significant probability and produces the H2 molecule with a considerable amount of vibrationnal energy. A simple mechanical model is presented, where desorption of the nascent H2 molecule results from two successive binary elastic collisions.