Laser generated ultrasound at modified metal surfaces

A study has been made of the ultrasonic pulses generated at modified metal surfaces by laser irradiation. Both longitudinal and shear acoustic modes have been investigated, generation at modified and free surfaces being compared. The use of a Q-switched Nd: YAG laser enabled experiments to be carried out at optical power densities above and below the threshold for plasma formation. Qualitative models of the acoustic sources existing in each case are proposed, which explain the experimental effects of surface modification; these include the observed changes in generation efficiency and longitudinal directivity.     

Magnet assisted fabrication of microtubule arrays

Magnetic fields were used to fashion permanently aligned microtubule arrays allowing formation of highly ordered platforms for assembly, separation, and single molecule motor studies.     

Activation of glassy carbon electrodes by alternating current electrochemical treatment

Glassy carbon electrodes subjected to “severe” electrochemical treatment is saturated chloride solutions exhibit enhanced electrochemical reversibility compared to untreated electrodes. Apparently faster rates of electron-transfer result in lowering of the overpotential by 110–300 mV for eight electroactive species tested. Systematic alterations in the response in terms of peak potential, sensitivity, background current, and stability are reported. Scanning electron micrographs show the introduction of pits of random size distribution. From the practical point of view, the most significant improvement is observed in differential pulse measurements, that are highly sensitive to small changes in the rate of electron transfer. In amperometric detection for liquid chromatography, the pretreated electrodes are shown to facilitate the quantitation of different eluting species. It appears that the surface and bulk properties of the glassy carbon have profound effects on the observed behavior.     

Highly stereoselective synthesis of cyclic primary amines via hydride reductions.

The Reduction of p,p'-dimethoxybenzhydryl imines of substituted cyclohexanones with lithium tri-sec-butyl or tri-ethylborohydride and subsequent cleavage of the resulting secondary amines with formic acid affords the corresponding axial cyclohexyl primary amines with high stereoselectivity.     

Developments in the Coordination Chemistry of Dicoordinate Phosphenium Ion Ligands

Abstract

Phosphenium ion ligands display synergic [sgrave]-donor, σ-acceptor properties which resemble other small molecules and the coordination chemistry of X₂P⁺ ligands is compared here with NO and SO₂.