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     

Aspects of nucleon Compton scattering

We consider the spin-averaged nucleon forward Compton scattering amplitude in heavy baryon chiral perturbation theory including all terms to order . The chiral prediction for the spin-averaged forward Compton scattering amplitude is in good agreement with the data for photon energies110 MeV. We also evaluate the nucleon electric and magnetic Compton polarizabilities to this order and discuss the uncertainties of the various counter terms entering the chiral expansion of these quantities.     

Production of fast evaporation residues by the reaction20Ne+208Pb at projectile energies of 8.6, 11.4 and 14.9 A.MeV

Velocity distributions and production cross sections of evaporation residues have been measured in the reaction²⁰Ne+²⁰⁸Pb at projectile energies of 8.6, 11.4, 14.9 A.MeV. Essential deviations from statistical model of deexcitation have been observed. Monte Carlo simulations involving emission of non-equilibrium particles have been used in order to reproduce experimental velocity, charge and mass distributions of evaporation residues and to estimate indirectly multiplicities of pre-equilibrium particles. Communicated by V. Metag     

Electrochemical oxidation of 6-hydroxy-1,2,3,4-tetrahydro-β-carboline in aqueous solution

The electrochemical oxidation of 6-hydroxy-1,2,3,4-tetrahydro-β-carboline (1), an alkaloid which occurs naturally in the mammalian brain, has been studied in aqueous solution particularly at physiological pH. The first voltammetric oxidation peak of 1 observed at the pyrolytic graphite electrode generates a radical intermediate which dimerizes to give 5,5′-bi-(6-hydroxy-1,2,3,4-tetrahydro-β-carboline) (3). However, the putative radical intermediate can also be further oxidized (1e) to give a C(5)-centered carbocation which can either dimerize in an ion-substrate reaction to give 3 or be attacked by water to give 5,6-dihydroxy-1,2,3,4-tetrahydro-β-carboline (8) which is rapidly oxidized further to 1,2,3,4-tetrahydro-β-carboline-5,6-dione (9). In the presence of glutathione dione 9 forms the 8-S-glutathionyl conjugate of 8 which is easily oxidized to the 8-S-glutathionyl conjugate of 9. It is suggested that 1 might be an alkaloid which is elevated in the brain as a result of chronic alcoholism, and the roles of the oxidative transformations of this compound in some of the addictive and neurophathological consequences of ethanol consumption are discussed.     

Single-run analysis of retinal isomers, retinol and photooxidation products by high-performance liquid chromatography

A high-performance liquid chromatographic (HPLC) procedure was developed to allow the rapid separation, in a single run, of a mixture of the main retinal isomers (all-trans, 13-cis, 9-cis), all-trans-retinol, and of the two major photooxygenated photoproducts (5,8-peroxyretinal and 5,6-epoxyretinal). The mixture was separated by HPLC on an octadecyl (ODS) column with 16% (v/v) diethyl ether in hexane as mobile phase and anthracene as the internal standard. A commercial type cosmetic formulation containing 0.05% all-trans-retinal was analyzed successfully for this analyte.     

Phase Selectively Soluble Dendritic Derivative of 4-(Dimethylamino)- pyridine: An Easily Recyclable Catalyst for Baylis-Hillman Reactions

Among the reactions in which C-C bonds are formed, the Baylis-Hillman coupling of aldehydes with α, β-unsaturated carbonylic compounds is currently attracting much interest due to the atom economy, the mild conditions and the generation of functional groups1,2. Furthermore, compared to the Heck, Suzuki and other palladium catalyzed C-C bond forming reaction3, the Baylis-Hillman reaction can be promoted by using organic bases in the complete absence of any metal4. However, almost all the …     

Slurry sampling for graphite furnace atomic absorption spectrometry

Summary Slurry preparations are an effective way to introduce solids into the graphite furnace. Ultrasonic agitation keeps samples mixed prior to analysis. Several aspects of the ultrasonic slurry sampling approach are discussed including contamination concerns, analyte partitioning, and the effect of particle size. In addition, sample preparation strategies for slurry preparations of non-powdered materials are reviewed. The suitability of this method for assessing homogeneity is demonstrated.     

The isotopes259106,260106, and261106

In irradiations of²⁰⁷Pb and²⁰⁸Pb, respectively, with⁵⁴Cr theα-decay of the isotopes²⁵⁹106,²⁶⁰106, and²⁶¹106 could be observed for the first time. For²⁶⁰106 a spontaneous fission branch of (50 _?20 ⁺³⁰ )% was observed. The isotopes were identified by genetic relationships of α-decay after separation in-flight with the velocity filter SHIP and implantation into a position-sensitive silicon surface-barrier detector. The measured partial fission halflife of the doubly even isotope²⁶⁰106 of (7.2 _?2.7 ^+4.8 )ms exceeds the predicted values by at least a factor of 40. This result could be explained by the high shell corrections of the ground state mass, derived from the measured α-decay energies. The experimental results show evidence for an island of purely shell stabilized nuclei in the region of deformed isotopes beyond the actinides.     

Synthesis and modeling study of (2S,5R,6R)- and (2S,5R,6S)-6-hydroxy- 8-(1-decynyl)-benzolactam-V8 as protein kinase C modulators

[structures: see text] Both (2S,5R,6R)- and (2S,5R,6S)-6-hydroxy-8-(1-decynyl)benzolactam-V8 were designed and synthesized as PKC modulators. Biological assays reveal the (6R)-ligand to be 20-fold more potent than its (6S)-counterpart in binding to PKC alpha.