An effective force field for molecular dynamics simulations of dimethyl sulfone

A rigid five-site united atom model for dimethyl sulfone (DMSO₂) compatible with the GROMOS force field is parametrized and tested. The parameters were optimized with respect to experimental quantities such as liquid density, heat of vaporization, shear viscosity and excess free energy. Good agreement with pure component properties is achieved except for the static dielectric permittivity which is calculated too low. Together with the SPC model for water the new DMSO₂ model was used to study aqueous mixtures at low concentrations and compared to aqueous mixtures of DMSO. It is concluded that interaction parameters for sulfoxide oxygen are not directly transferable to sulfonyl oxygen.     

Recent advances in the organic synthesis at high pressure. Effect of pressure on the macrocyclization reaction

Abstract

α,ω-Tertiary diamines react under high pressure with α,ω-di-iodo compounds to give cyclic or bicyclic bis-quaternary salts in almost quantitative yields. The role of high-pressure-induced changes in conformation of linear intermediates and the viscosity factor are discussed.     

Investigation of neutron emission from relativistic heavy ion interactions by nuclear tracks

Fast neutrons produced in 44 and 22 GeV ¹²C+Cu interactions have been recorded and analysed with a CR-39 detector stack. The irradiation of the CR-39 stack to fast neutrons was carried out at the accelerator Synchrophasotron, Joint Institute for Nuclear Research, Dubna, Russia. Areal and volume densities of tracks induced by fast neutrons in the CR-39 at different positions and for different etching time have been measured. The neutron production ratio of 44 GeV to 22 GeV ¹²C+Cu interactions has been obtained, which is 2.17 ± 0.30 by areal track density, or 2. 12±0.33 by step etch technique, or 2.03±0.34 by volume track density measurement. These results confirm that the production rate at 44 GeV ¹²C+Cu interactions is more than theoretical estimation.     

Conduction studies on electrodeposited indium selenide thin films

Indium Selenide thin films were electrodeposited on Indium Tin Oxide (ITO) coated glass substrates from a mixture of Indium trichloride (InCl₃) and selenium dioxide (SeO₂) in aqueous solution by the potentiostatic electrodeposition technique. The InSe films showed that Mott’s variable-range hopping conductivity (VRH) is dominant under low field (∼2×10⁵ Vcm⁻¹) condition. At high field the Current-Voltage studies (in the temperature range 300 – 380 K) revealed that the conductivity of Indium selenide thin films is of Poole-Frenkel type. The plot drawn between Ln (I/V) and tV showed a straight line and also the experimental data and the theoretical data closely matches. Hence Poole-Frenkel mechanism is confirmed and discussed in detail. Paper presented at the 2nd International Conference on Ionic Devices, Anna University, Chennai, India, Nov. 28–30, 2003.     

Celtine,celtisine and breoganine,new phenolic cularine alkaloids from fumariaceae

Three new phenolic cularines have been isolated from Sarcocapnos and Corydalis species. Their structures have been elucidated on the basis of spectroscopic studies and chemical transformations.     

Prescribed Mean Curvature Hypersurfaces in Hn+1(-1) with Convex Planar Boundary, I

We study immersed prescribed mean curvature compact hypersurfaces with boundary in Hⁿ⁺¹(-1). When the boundary is a convex planar smooth manifold with all principal curvatures greater than 1, we solve a nonparametric Dirichlet problem and use this, together with a general flux formula, to prove a parametric uniqueness result, in the class of all immersed compact hypersurfaces with the same boundary. We specialize this result to a constant mean curvature, obtaining a characterization of totally umbilic hypersurface caps.     

Generation of the derivative of out-of-plane displacements in the high-sensitivity grating interferometry configuration

A simple method for determining the surface slope of a specimen under test in the high-sensitivity grating interferometry setup is proposed. The information on the derivative of out-of-plane displacement is obtained by software subtraction of two primary interferograms: a conventional one and one with diffraction orders laterally displaced in the image plane. Very good coincidence between the theoretical and experimental results has been obtained. The method can be used for studying static and transient events depending on the fringe pattern analysis method used.     

New oxidized isocularine alkaloids from sarcocapnos plants

Structures 1a, 3 and 6 were deduced for the new oxoisocularine alkaloids, oxosarcophylline, yagonine and aristoyagonine, respectively, on the basis of spectroscopic studies and synthesis.