Application of single point imaging (SPI) to solid state materials.

Single Point Imaging (SPI) is a 3D phase encoding MRI method proposed by S. Emid and J.H.N. Creyghton [1] to study solid state materials with a very short T(2) value (>50 micros). In this short communication experimental results of SPI applications to various industrial important solid materials, such as porosity of chocolate samples, connectivity of micro-channels in earth samples, etc. are reported.     

High pressure neutron-scattering experiments on phospholipid model biomembranes

Abstract

By use of neutron small-angle scattering (SANS) the structural properties of saturated and unsaturated phosphatidylcholine model biomembrane systems have been investigated in the temperature range from 0°C to 70°C and at pressures up to 3.5 kbar. The effect of chemical constitution of the hydrocarbon chains of the lipids and the effect of cholesterol on the thermotropic and barotropic phase behaviour is discussed.     

UV light‐mediated alkylation of inorganic selenium

In the presence of low molecular weight organic acids (formic, acetic, propionic and malonic), inorganic selenium(IV) is converted by UV irradiation to volatile selenium carbonyl, dimethylselenide and diethylselenide, depending on the acid used. Gas chromatography–mass spectrometry analysis of the volatile products shows that, in 0.7 M formic acid solution, approximately 60–70% (v/v) SeH₂ and 30–40% (v/v) SeCO are formed. The presence of nitrate ion appears to increase threefold the formation of SeCO while completely suppressing formation of SeH₂. Copyright © 2003 Crown in the right of Canada. Published by John Wiley & Sons, Ltd.     

Homogenization of the Three-dimensional Hall Effect and Change of Sign of the Hall Coefficient

The notion of a Hall matrix associated with a possibly anisotropic conducting material in the presence of a small magnetic field is introduced. Then, for any material having a microstructure we prove a general homogenization result satisfied by the Hall matrix in the framework of the H-convergence of Murat–Tartar. Extending a result of Bergman, we show that the Hall matrix can be computed from the corrector associated with the homogenization problem when no magnetic field is present. Finally, we give an example of a microstructure for which the Hall matrix is positive isotropic almost everywhere, while the homogenized Hall matrix is negative isotropic.     

Neutralization of Na+-ions in grazing scattering from the surface of thin Al-films

A theoretical study on the formation of the Na I 3s-term in grazing scattering of Na⁺-ions from the (111)-surface of an aluminum crystal and a thin film is performed. For the crystal-surface we find quantitative agreement between experimental and theoretical results. For a thin film the quantization of the electronic states in the direction normal to the surface strongly influences the charge-exchange process. The dependence of the neutral fractions in the scattered beam on the projectile velocity is predicted to be clearly different for electron capture from the film and the semi-infinite crystal.