Convergence Towards the End Space for Random Walks on Schreier Graphs

Journal of Theoretical Probability - We consider a transitive action of a finitely generated group G and the Schreier graph $$\varGamma $$ defined by this action for some fixed generating set. For...     

Preliminary studies on arsenic species in some environmental samples

Arsenic compounds have been determined in some environmental samples from the German Environmental Specimen Bank (ESB) (marine mussels, freshwater mussel and fish, sea-gull eggs) and certified reference materials (DORM-1, DOLT-1, NBS Oyster Tissue) after separation by open column cation and anion exchange chromatography by two different methods of total arsenic determination in separated fractions (instrumental neutron activation analysis or hydride generation atomic absorption spectrometry). Arsenobetaine has been identified as the major species in all the different materials.     

A functional relation among the pair correlations of the two-dimensional one-component plasma

We map the classical two-dimensional one-component plasma of charged particles with coupling constant an even positive integer onto a one-dimensional fermionic system. We then show that, in the thermodynamic limit of the fluid regime, translational invariance of the two-body density implies an infinite sequence of interrelations among the coefficients of its short-distance expansion. The existence of these sum rules turns out to be related to a general symmetry of the Coulomb system, providing a functional relation for the two-body density for arbitrary coupling .     

Stereoelectronic effects of substituents at silicon on the hydrosilylation of 1-hexene catalysed by [RhCl(cod)(1-hexene)]

Summary Trisubstituted silanes, HSiR_3-n X _n (R = Me or Et, X = Cl, OEt, or Ph; n = 0–3) oxidatively add to the complex [RhCl(cod)(1-hexene)] (cod = cycloocta-1,5-diene) to yield [RhCl(cod)(1-hexene)(H)(SiR₃)] [(1)]. Subsequent steps of hydrosilylation follow, i.e. cis-insertion of the alkene (- rearrangement) and then reductive elimination of the product, according to the general Chalk and Harrod scheme. A quantitative correlation between the second order rate constant, k ₁, of the oxidative addition (followed spectrophotometrically) at 20°C in benzene solution and the structure of the trisubstituted silane represented by Stereoelectronic parameters , and E' for the SiR_3-n X _n groups was established. The maximal hydrosilylation rate followed by g.l.c., is strongly retarded by highly electronegative substituents X on silicon and results from the elimination rate of the hydrosilylation product from (1) and the maximal concentration of (1) in solution.Dedicated to Professor K. Rühlmann on the occasion of his 65th birthday. Part XXVII in the series Catalysis of Hydrosilylation; for Part XXVI see Polish J. Appl. Chem., 38, 169 (1994).     

World spinors—Construction and some applications

The existence of a topological double-covering for the GL(n, R) and diffeomorphism groups is reviewed. These groups do not have finite-dimensional faithful representations. An explicit construction and the classification of all (n, R), n=3,4 unitary irreducible representations is presented. Infinite-component spinorial and tensorial fields, “manifields”, are introduced. Particle content of the ladder manifields, as given by the (3, R) “little” group, is determined. The manifields are lifted to the corresponding world spinorial and tensorial manifields by making use of generalized infinite-component frame fields. World manifields transform w.r.t. corresponding representations, which are constructed explicitly. Supported in part by the Science Foundation (Belgrade).     

Comment on determination of electron temperature from Langmuir probe data in tokamak edge plasma

Langmuir probe measurements of electron temperature in a plasma in the limiter shadow of a tokamak are presented together with a method of probe data analysis which takes into account the influence of the ion current vs voltage dependence in the determination of electron temperature, The method is based on the transformation of a single into a double probe characteristic. Values of the electron temperature calculated using this method are compared with the values estimated from single probe characteristic data.     

Superplasticity in single-phase Zn-0·25 wt. % Cd alloy

A single-phase Zn-0·25 wt. % Cd alloy was prepared with the mean grain sized¯ 1m. Superplastic characteristics (A _max=320% andm _max>0·4) were established at room temperature at the strain rates.10^–4s^–1. Because of the absence of any second phase particles the fine-grained structure was not stable and an intense grain coarsening was observed both during the long-term ageing and during straining at room temperature. The increasing temperature accelerated this grain coarsening and suppressed the superplastic behaviour. Nevertheless, the stress relaxation tests suggested that the superplastic behaviour might be expected at higher temperatures in coarser grained specimens, too, but at substantially lower strain rates.     

Optimization of energy consumption for NOx removal in multistage gas irradiation process

Previously reported results of the tests performed on industrial pilot plant for EB flue gas treatment has proved the theoretical assumption that multistage gas irradiation leads to power consumption savings in comparison with single gas irradiation process. In this paper the results of theoretical and experimental studies are presented concerning optimization of the ratio of dose distribution between the particular stages. Nonuniform dose distribution causes further decrease in power consumption for NO_x removal.     

Investigation of {1,2-bis(diphenylphosphino)ethane-P,P′}-(dithiocarbonato-S,S′)-nickel(II)

Summary The reaction of bis(iso-propylxanthato)nickel(II) with 1,2-bis(diphenylphosphino)ethane (dppe) in a 11 molar ratio affords [Ni(S₂CO)(dppe)], which, on the basis of its magneto-chemical and spectral properties, has been characterized as a square-planar Ni complex. The complex was one-electron irreversibly oxidized at a potential of 0.673 V versus s.c.e. The crystal and molecular structure of a twinned crystal of the complex has been elucidated, and consists of two crystallographically independent molecules in which each Ni atom is coordinated by two S atoms from the dithiocarbonate ligand and two P atoms from the dppe ligand in an approximately square-planar arrangement.