On the lattice of weak congruence relations

We consider the setC _w (A) of weak congruences on an algebraA, i.e. of all symmetric and transitive subalgebras ofA ×A. (Some other generalizations of compatible relations were given in [2] and [6]).C _w (A) coincides with the set of all congruences on all subalgebras ofA.We prove here that (^iC _w(A),) is an algebraic lattice having as a sublattice the lattice of all congruences onA, and as a retract the lattice of all its subalgebras. In the second part we give necessary and sufficient conditions (one is the CEP) for modularity as well as for distributivity of the lattice of weak congruences.Presented by H. P. Gumm.     

Off-shell effects inpp↔πd spin observables

We show that spin observables inppd are fairly sensitive to small changes in the off-shell N helicity amplitudes. This is illustrated at proton laboratory kinetic energies ofT _p=515 MeV andT _p=578 MeV. A reduction of the helicity-flip amplitude by 13% brings the predictions of the relativistic rescattering model much closer to experiment.     

A simple current pulsed low-pressure CO2 laser with passive Q-switching

We report on a simple and stable pulse tunable CO₂ laser suitable for many investigations in the region around 10m. The pulsed discharge when combined with the passiveQ-switching technique provides pulses of 100 ns duration with a peak power of few kilowatts.Due to the interest in pulsed low-pressure CO₂ lasers as useful irradiation sources, extensive investigations have been carried out. In particular, various Q-switching techniques have been developed to generate short CO₂ laser pulses [1–4].     

Interaction of 1-methyl-1-({2-[4-(trifluoromethyl)phenyl]-1,3-thiazol-4-yl}methyl) piperidinium chloride with β-CD: spectroscopic,calorimetric and molecular modeling approaches

Spectroscopic investigation supported by molecular modeling methods has been used to describe the inclusion complex of β-cyclodextrin (β-CD) with 1-Methyl-1-({2-[4-(trifluoromethyl)phenyl]-1,3-thiazol-4-yl}methyl) piperidinium chloride (1MPTMPC) in solution and in solid state. The formation of inclusion complex between the β-CD and the 1MPTMPC has been investigated both in solution and in the solid state. Solution-state complexation between the 1MPTMPC and β-CD was established using ¹H NMR spectroscopy and isothermal titration calorimetry (ITC). From the ¹H NMR spectroscopic studies, 1:1 complex stoichiometry was deduced with an association constant (K) of 925 M^?1. Using an independent binding model, the ITC technique provides a K value of the same order with the one determined by NMR and the thermodynamic parameters ΔH, ΔS and ΔG which reveals driving forces involved during complex formation. The formation of the solid inclusion compound was confirmed by X-ray powder diffraction and differential scanning calorimetry. The most probable conformation of the inclusion complex obtained through a molecular docking investigation corroborates well to ROESY experiment.     

Electrochemical detection and removal of pharmaceuticals in waste waters

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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).