Measurement of γp→K + Λ and γp→K + Σ 0 at photon energies up to 1.47 GeV

The reactions pK ⁺ and pK ^{+ 0} have been measured with the multiparticle detector system SAPHIR at ELSA in Bonn. Besides the differential cross sections the polarization and, for the first time, the ⁰ polarization have been determined in a photon induced reaction. All data are presented as functions of the photon energy (from threshold up to 1.47 GeV) and of the kaon production angle (0°–180°). The polarization of both and ⁰ is substantial at all energies and varies strongly with the production angle.This work is supported by the Bundesminister für Forschung und Technologie (BMFT), FK 06 BN 621 I     

Vanillic acid 4-O-beta-D-(6'-O-galloyl) glucopyranoside and other constituents from the bark of Terminalia macroptera Guill.et Perr

A new phenolic glucoside gallate, vanillic acid 4-O-beta-D-(6'-O-galloyl) glucopyranoside (1) was isolated from the bark of Terminalia macroptera Guill.et Perr., together with 3,3',4'-tri-O-methylellagic acid (2) and two triterpene glucopyranosyl esters, 24-deoxysericoside (3) and chebuloside II (4). Compounds 2-4, not described previously for this plant, showed antimicrobial activities against Bacillus subtilis, while 3 and 4 possessed haemolytic properties. In both assays 1 was found to be inactive.     

Synthesis of stable and cell-type selective analogues of cyclic ADP-ribose, a Ca(2+)-mobilizing second messenger. Structure--activity relationship of the N1-ribose moiety

We previously developed cyclic ADP-carbocyclic ribose (cADPcR, 2) as a stable mimic of cyclic ADP-ribose (cADPR, 1), a Ca(2+)-mobilizing second messenger. A series of the N1-ribose modified cADPcR analogues, designed as novel stable mimics of cADPR, which were the 2"-deoxy analogue 3, the 3"-deoxy analogue 4, the 3"-deoxy-2"-O-(methoxymethyl) analogue 5, the 3"-O-methyl analogue 6, the 2",3"-dideoxy analogue 7, and the 2",3"-dideoxydidehydro analogue 8, were successfully synthesized using the key intramolecular condensation reaction with phenylthiophosphate-type substrates. We investigated the conformations of these analogues and of cADPR and found that steric repulsion between both the adenine and N9-ribose moieties and between the adenine and N1-ribose moieties was a determinant of the conformation. The Ca(2+)-mobilizing effects were evaluated systematically using three different biological systems, i.e., sea urchin eggs, NG108-15 neuronal cells, and Jurkat T-lymphocytes. The relative potency of Ca(2+)-mobilization by these cADPR analogues varies depending on the cell-type used: e.g., 3"-deoxy-cADPcR (4) > cADPcR (2) > cADPR (1) in sea urchin eggs; cADPR (1) > cADPcR (2) approximately 3"-deoxy-cADPcR (4) in T-cells; and cADPcR (2) > cADPR (1) > 3"-deoxy-cADPcR (4) in neuronal cells, respectively. These indicated that the target proteins and/or the mechanism of action of cADPR in sea urchin eggs, T-cells, and neuronal cells are different. Thus, this study represents an entry to cell-type selective cADPR analogues, which can be used as biological tools and/or novel drug leads.     

First enzymatic synthesis of an N1-cyclised cADPR (cyclic-ADP ribose) analogue with a hypoxanthine partial structure: discovery of a membrane permeant cADPR agonist

Nicotinamide 8-Br-hypoxanthine dinucleotide (8-Br-NHD+) was cyclised at the N1 position by the ADP-ribosyl cyclase from Aplysia californica to give cyclic 8-Br-inosine diphosphoribose (8-Br-N1-cIDPR), a novel membrane-permeant agonist of Ca2+ release in human T cells.     

Polymorphic transformation in TlSe and the electrical properties of phases

Alloys in the TlSe-Se system on the side of the TlSe compound in the phase diagram have been investigated using differential thermal, X-ray powder diffraction, and microstructural analyses. The phase diagram of the system has been constructed, and the temperature dependences of the electrical conductivity of the phases obtained have been examined. An analysis of the thermograms of alloys in the (TlSe)_0.96-Se_0.04 system has revealed a structural phase transition at a temperature of 470 ± 1 K. Investigations into the temperature dependences of the electrical conductivity in the range 120–450 K have demonstrated that the temperature dependence of the electrical conductivity for the (TlSe)_0.96-Se_0.04 alloy exhibits metallic behavior.     

Manganese hydride potential energy curves

The potential energy curves of the ⁷Σ⁺ and the ⁵Σ⁺ states of MnH are calculated using restricted Hartree-Fock, unrestricted Hartree-Fock and the perfect pairing generalized valence bond methods. Both of these states are bound, with the ⁷Σ⁺ lowest in energy. The bonding for both states is to the 4s² shell rather than to any of the five singly occupied d orbitals. The MnH bonding orbitals are sp hydribs. These results are compared to similar studies of H on Sc, Fe, Ni and Cu. The implications of these results to hydrocarbon catalysis by first row transition metal catalysis are considered.     

Perturbation calculation of atomic correlation energies for the first transition period

Results are presented for calculations of Hartree—Fock and correlation energies for the 3dⁿ 4s² and 3dⁿ⁺¹ 4s ground and excited states of the first transition series atoms using second-order Møller—Plesset perturbation theory starting with an unrestricted Hartree—Fock wavefunction.     

A direct synthetic approach to vanadium pentoxide nanofibres modified with silver nanoparticles

Small amounts of silver ions have been found to significantly enhance the growth rate of vanadium pentoxide (V(2)O(5)) nanofibres in aqueous solution at room temperature, yielding fibres with lengths of several micrometers within a few days; the V(2)O(5) fibres are decorated with silver nanoparticles with sizes in the range of 5-15 nm, which opens perspectives for applications in chemical sensors.