PHOTOREACTIVITY OF 5-GERANOXYPSORALEN AND LACK OF PHOTOREACTION WITH DNA

5-Geranoxypsoralen, commonly called bergamottin, a major furocoumarin contained in bergamot oil, is reported in vitro as a highly photoreactive psoralen. In ethanol, it exhibits quite a high triplet state quantum yield (approximately 0.37). The triplet state is involved in subsequent photochemistry which depends on the initial concentration and on the presence of oxygen. In contrast to most psoralens, absorption and fluorescence data suggest that 5-geranoxypsoralen does not interact with DNA in the dark. No UVA-induced interstrand cross-links in DNA were shown.     

From the Hamiltonian to the Lagrangean formalism for 1-reducible theories. The Freedman-Townsend model

The paper presents a possible path to the sp(3) BRST Lagrangean formalism for a 1-reducible gauge field theory starting from the Hamiltonian one. This appears to be not at all a trivial attempt and will allow explanation of the structure of generators and the form of the master equations in the Lagrangean sp(3) theories. The Freedman-Townsend model, for which a Lagrangean (covariant) sp(3) theory is important, is presented.     

Structure formation under steady-state isothermal planar elongational flow of n-eicosane: a comparison between simulation and experiment

We use nonequilibrium molecular dynamics simulations to investigate the structural properties of an oriented melt of n-eicosane under steady-state planar elongational flow. The flow-induced structure was evaluated using the structure factor s(k) taken as the Fourier transform of the total pair correlation function g(r). We found that the equilibrium liquid structure factor is in excellent agreement with the one determined via x-ray diffraction. Moreover, a new x-ray diffraction experiment has been performed on a crystalline n-eicosane sample. The resulting intramolecular contribution to the structure factor was found to be in very good agreement with the simulated one at a high elongation rate, indicating the existence of a possible crystalline precursor structure.     

Differential non-destructive image current detection in a fourier transform quadrupole ion trap

Dual-detector differential non-destructive Fourier transform detection in a quadrupole ion trap is shown to improve signal intensity and reduce noise compared with spectra recorded using a single detector. A larger area detector in each end-cap electrode is machined to fit its hyperbolic shape and so minimize field imperfections on the z-axis. Argon, acetophenone and bromobenzene spectra were recorded to allow a comparison between single- and dual-detector (differential) modes of detection and to demonstrate the improvement achieved with differential detection. Copyright 1999 John Wiley & Sons, Ltd.     

Orthotropic strain rate potential for the description of anisotropy in tension and compression of metals

In this paper, a macroscopic anisotropic strain rate potential, which can describe both the anisotropy and tension-compression asymmetry of the plastic response of textured metals is derived. This strain rate potential is the exact work-conjugate of the anisotropic stress potential CPB06 of Cazacu et al. (2006). Application of the developed strain rate potential to HCP high-purity alpha-titanium is presented.     

Overall kinetic model for oscillating catalytic oxidation of methanol

An overall kinetic model for the deep catalytic oxidation of methanol is presented. It is based on the balance of chemical species and could described self-sustained oscillations.

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Quantum study of the active sites of the γ alumina surface (II): QM/MM (LSCF) approach to water, hydrogen disulfide and carbon monoxide adsorption

The mixed quantum mechanics/molecular mechanics (QM/MM) local self consistent field (LSCF) method is applied to study the adsorption of water, hydrogen sulfide, and carbon monoxide molecules on γ alumina surfaces. The effect of the long-range contributions included in the LSCF adsorption/dissociation energies are compared to cluster results. For the carbon monoxide, the long-range contributions do not change the adsorption energies in comparison with the cluster approach. In opposition, the long-range contributions lower the adsorption and dissociation energies of water and hydrogen disulfide. Cautions to be taken on the application of the LSCF method to γ alumina are also discussed.     

Nafronyl ion-selective membrane electrodes and their use in pharmaceutical analysis

A simple potentiometric method is described for the rapid determination of nafronyl-drugs in pharmaceutical preparations such as tablets. Nafronyl ion-selective membrane electrodes with either the nafronyl-dipicrylamine ion-pair complex in 1,2-dichloroethane or the nafronyl-dinonylnaphthalenesulphonic acid ion-pair complex in a PVC matrix as electroactive materials were used. Both electrodes exhibit near-Nernstian responses to protonated-nafronyl activity from 10(-2) to about 10(-5)M, in pH ranges that depend on the nature of the electroactive material used in the membrane. Nafronyl in the mg-range can be determined by potentiometric titration with sodium tetraphenylborate solution, with a relative standard deviation of less than 2.0%. No interference from any excipients in the tablets was observed.     

Kinetic model for methanol conversion over Mg-ZSM-5 zeolite

The catalytic conversion of methanol to olefins over ZSM-5 zeolite modified by ion exchange with Mg exhibits an autocatalytic character. On this basis an overall kinetic model of the reaction was proposed which allowed the determination of rate constants and apparent activation energy.

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