Dipole rotational band in137Nd

It is suggested that nuclear reactions induced by medium mass projectiles, with A/q close to that of the primary beam, could explain the anomalous positron-electron peaks observed in sub-barrier collisions of very heavy nuclei. The reactions result in prominent -rays which convert to e⁺e^– pairs in material near the target. Possible experiments to examine this hypothesis are suggested.     

Mechanistic studies of reactions catalysed by diamine oxidase using isotope effects

Diamine oxidase (DAO), the enzyme that is responsible for amine biodegradation in animals, plants and humans, catalyses the biotransformation of amines such as histamine (HA), putrescine, 1-phenylethylamine, tyrosine, tryptamine, serotonine and spermine. The kinetic and solvent isotope effects (SIEs) were applied to study the mechanism of the biotransformation using HA and its methylderivatives. The SIE for the biotransformation of HA, N^τ-methylhistamine and N^π-methylhistamine was found to be 3.58, 2.22 and 5.70 on V_max, and 1.58, 1.06 and 1.14 on V_max/K_M, respectively. On the other hand, the kinetic isotope effect for oxidation of stereospecifically deuterium-labelled [(α R)-²H]-N^τ-methylhistamine and [(α R)-²H]-N^π-methylhistamine was 0.69 and 0.62 on V_max, and 15.06 and 7.50 on V_max/K_M, respectively. These results demonstrate that DAO catalyses amine biotransformation by stereospecifically cleaving the αC\bond H bond in the pro-S position. Moreover, the oxidation of amine to aldehyde involves several transition states, including hybridisation change from sp³ (Schiff base) to sp² (imine), then back again to sp³ to give a final product with hybridisation sp² (aldehyde).     

On the electronic contribution to the elastic constants in strained quantum wire superlattices of non-parabolic semiconductors with graded structures: Theory and suggestion for experimental determination

Summary  We study the electronic contribution to the second- and third-order elastic constants in strained quantum wire superlattices of non-parabolic semiconductors with graded structures and compare the same with the constituent materials, by formulating the appropriate dispersion laws. It is found, taking InSb/GaSb quantum wire superlattice as an example, that the said contributions increase with decreasing thickness and with increasing electron concentration in oscillatory manners together with the fact that the influence of the finite interface width enhances their numerical values. An experimental method is suggested for determining the electronic contribution to the elastic constants in materials having arbitrary dispersion laws. In addition, the well-known results for constituent semiconductors in the absence of stress have also been obtained as special cases of our generalized formulations.