Σatomic states and the nucleon distribution in Pb

The analyses of (K^-,π) and (π^-, K⁺) reactions indicate that the nuclear potential of the Σ-hyperon is repulsive inside the nucleus, in agreement with the prediction of model F of the Nijmegen baryon-baryon interaction. This is consistent with the recent calculation of the strong-interaction shifts and widths of the observed levels of Σ^- atoms, including the precise data on the Σ^-Pb atom. In this paper, the sensitivity of this calculation to the neutron and proton density distributions is used to determine these densities in ²⁰⁸Pb.     

Kinetics of decomposition pathways of an energetic GZT molecule

This investigation uses the Gaussian 98 program, density functional theory (DFT) B3LYP/6‐31G(d,p), and ab initio MP2/6‐31G(d,p) and HF/6‐31G(d) methods to model energetic diguanidinium 5,5′‐azotetrazolate (GZT) ionic species in order to determine their decomposition mechanisms. GZT was initially cracked into two guanidinium cations (G⁺) and a 5,5′‐azotetrazolate anion (ZT^2?). Three routes—the elimination of a hydronium ion (H⁺), the elimination of a hydrogen radical (H·), and the elimination of an amine radical (·NH₂)—are suggested for the decomposition of the G⁺ cation, and three routes—single ring opening, double ring opening and N? N bond cleavage outside the ring—are proposed for the further decomposition of the ZT^2? anion. Fourteen decomposition species were obtained on splitting both the cation and anion. This result reveals the reliability of the aforementioned decomposition mechanisms. The transition state species were also obtained using a two‐structure or three‐structure synchronous transit‐guided quasi‐Newton (STQN) between the Cartesian coordinates of related particles at specific decomposition stages in this research. The corresponding activation energies in all decomposition stages were considered to infer the most feasible pathways of GZT decomposition. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008     

Solid phase synthesis of benzamidine and butylamine-derived hydantoin libraries

We have constructed a number of benzamidine- and butylamine-based hydantoin compounds by means of an efficient route using solid phase synthesis in which neat diisopropylamine was employed for a novel cyclization/traceless cleavage step. All library compounds were obtained in excellent yield and high purity. This revised version was published online in August 2006 with corrections to the Cover Date.     

Improved methods for supergraphs

We introduce some new techniques into superfield perturbation theory which allow considerable simplifications in calculations. As a result, we show that all contributions to the effective action can be written as integrals over a single d⁴θ. We also give the background group field formalism for supersymmetric non-abelian gauge theories. To illustrate our methods, we give examples of loop calculations: in particular, we show that in O(4) extended supersymmetric non-abelian gauge theories all one-loop propagator corrections cancel identically (both infinite and finite parts) and that these theories, at one loop, are finite and have no renormalizations (in the Fermi-Feynman gauge).     

Polyethylene/poly(styrene-co-divinylbenzene) sodium sulphonate membranes : Part 1. Synthesis and properties

Transport properties of cation-exchange membranes have been studied. The self-diffusion coefficients of sodium and chloride ions, the transport numbers of sodium ions and water, and the conductivities were measured in 0.1 M sodium chloride at 25°C. The concentration potentials were determined in the system 0.05/0.15 M sodium chloride.The membranes were prepared by sulphonation of oriented polyethylene (PE) film modified with 30 wt % of styrene—divinylbenzene copolymer (poly(St-co-DVB)). The copolymer was introduced by interpolymerization of the monomers within the film without its dissolution. A sequence of membranes having similar ion-exchange capacity but differing in water content was then obtained from sheets of normal PE/poly(St-co-DVB)SO₃Na membranes by expanding them by heating in water followed by a thermal treatment in air.The deviations of the measured transport properties from the behaviour of homogeneous membranes and the analysis of the Kedem—Katchalsky relationships for composite membranes have led to the conclusion that in PE/poly(St-co-DVB)SO₃Na membranes a structure prevails with a series arrangement of layers with different properties.     

Anwendungsmöglichkeiten des Anionenaustausches mit Salpetersäure-Methanol-Gemischen für die Trennung der Seltenen Erden

Der Anionenaustausch mit Salpetersäure-Methanol-Gemischen kann erfolgreich zur Reindarstellung vieler Elemente genutzt werden. Es werden Möglichkeiten der praktischen Anwendung solcher Glemische für die Trennung der leichten Lanthaniden, für die Reinigung der Lanthaniden von Zr und Hf und die Ausnutzung fūr die Produktion von radioaktiven Isotopen genannt.     

Layered TiO2 :PVK nano-composite thin films for photovoltaic applications

The influence of the solvent used for spin-coating on the homogeneity of poly(N-vinylcarbazole) (PVK) films is investigated. Homogenous films are obtained only by the use of toluene, solution in tetrahydrofuran (THF) and chloroform results in radially oriented inhomogeneities and films prepared by use of N-methylpyrrolidone and dimethylacetamide show particle formation during spin-coating. Layered nano-composite thin films are prepared by spin-coating a PVK film on top of a nano-structured titanium dioxide ( TiO2) layer. The TiO2 thin films are prepared by a sol-gel process using an amphiphilic copolymer as structure-directing agent. Structural characterisation of the TiO2 :PVK nano-composite films is done by field emission scanning electron microscopy (FESEM) and grazing-incidence small-angle scattering (GISAXS). Bare TiO2 films are probed for comparison. Light is basically only absorbed in the ultraviolet regime and absorption slightly increases upon addition of PVK, which makes the layered TiO2 :PVK nano-composite thin films good candidates for UV photovoltaic devices. Furthermore, absorption remains stable over a period of several days.