EFFECT OF ULTRASOUND ON THE KINETICS OF OXIDATION OF OCTAN-2-OL AND OTHER SECONDARY ALCOHOLS WITH SODIUM-BROMATE, MEDIATED BY RUTHENIUM TETRAOXIDE IN A BIPHASIC SYSTEM

The initial rate of oxidation of octan-2-ol and other secondary alcohols to their ketones with NaBrO3, mediated by RuO4 in an aqueous-CCl4 biphasic system, is greater with ultrasonic irradiation than by stirring alone. Under ultrasonic irradiation the initial rate of oxidation of octan-2-ol increases with increasing % duty cycle, [RuO4] and [NaBrO3]. The kinetics of alcohol oxidation appear to be closely linked with the oxidative dissolution of RuO2 to RuO4 by NaBrO3. The observed enhancement in rate with ultrasonic irradiation appear to be association, at least in part, with the increase in interfacial surface area via the formation of an emulsion of aqueous microdroplets containing NaBrO3 in the CCl4 layer containing the non-water-soluble secondary alcohol.

EFFECT OF ULTRASOUND ON THE KINETICS OF REDUCTION OF HEXACYANOFERRATE(III) BY THIOSULFATE IONS MEDIATED BY RUTHENIUM DIOXIDE HYDRATE

Ultrasound promotes the reduction of hexacyanoferrate(III) by thiosulfate ions mediated by RuO2 . xH(2)O under diffusion-controlled conditions. There is a strong correlation between the measured first-order rate constant and the absorbance of the dispersion, which, in turn, is closely related to the specific surface area of the catalyst. The enhancement in rate with ultrasonic irradiation appears to be largely associated with the dispersive action of the ultrasound on the aggregated particles of RuO2 . xH(2)O. The rate of reaction increases with increasing %duty cycle and ultrasonic intensity. The measured overall activation energies for the reaction with and without ultrasound, i.e. 18 +/- 1 and 20 +/- 1 kJ mol(-1), respectively, are very similar to those expected for a diffusion-controlled reaction. The homogeneous reaction is not promoted by ultrasound.

EFFECT OF PH ON THE STABILITY OF TIO2 COATINGS ON GLASS PHOTOCATALYSIS REACTORS FOR WATER-PURIFICATION

TiO2 coated glass shows excellent stability in the range pH 2-9, however, there is rapid and complete stripping of the TiO2 coating between pH 11 and 12.

THE EFFECT OF DIAMPHENETHIDE ON PROTEIN-SYNTHESIS BY THE LIVER FLUKE, FASCIOLA-HEPATICA

The effect of the deacetylated (amine) metabolite of diamphenethide (DAMD, 10 mug ml-1) on the uptake and incorporation by adult Fasciola hepatica of radioactively labelled precursors of DNA, RNA and protein synthesis ([H-3]thymidine, [H-3]uridine and [H-3]leucine, respectively) was measured by liquid scintillation counting. Comparison was made between the effects of DAMD and those of specific inhibitors of DNA, RNA and protein synthesis, namely, 5-fluorouracil, cordycepin and cycloheximide, respectively. DAMD caused a significant decrease in the overall uptake and incorporation of [H-3]uridine by F. hepatica, decreased the incorporation of [H-3]leucine and also caused a significant decrease in the overall protein content of the flukes. The effect of DAMD was similar to that of cycloheximide (I x 10(-3) M), a potent inhibitor of protein synthesis, which also caused a significant decrease in the incorporation of [H-3]leucine by the fluke and a decrease in the overall protein content of the fluke. Cordycepin(100 mug ml-1) caused a significant decrease in the protein content of the fluke, but had no effect on the uptake or incorporation of [H-3]uridine. 5-Fluorouracil (I x 10(-4) m) did not affect the uptake or incorporation of VH]thymidine, nor did it decrease the protein content of the fluke. The results indicate that DAMD inhibits protein synthesis by F. hepatica, possibly by inhibiting RNA synthesis. The results are also consistent with previous morphological investigations involving DAMD.

EFFECT OF EXERCISE ON THE NASAL TRANSMUCOSAL POTENTIAL DIFFERENCE IN PATIENTS WITH CYSTIC-FIBROSIS AND NORMAL SUBJECTS

Background - Normal subjects have a negative nasal transmucosal potential difference (TPD) at rest which becomes more negative with exercise. Patients with cystic fibrosis have a more negative resting nasal TPD than controls. The present study was designed to determine the effects of exercise on the TPD of patients with cystic fibrosis.

The effect of nicotine on basophil histamine release

Background:Changes in the immune and inflammatory response are induced by smoking tobacco but underlying mechanisms remain to be elucidated.

Effect of glucose on endothelin-1-induced calcium transients in cultured bovine retinal pericytes

Published work has shown that endothelin-l-induced contractility of bovine retinal pericytes is reduced after culture in high concentrations of glucose. The purpose of the present study was to establish the profile of endothelin-l-induced calcium transients in pericytes and to identify changes occurring after culture in high concentrations of glucose. Glucose had no effect on basal levels of cytosolic calcium or on endothelin-l-induced calcium release from intracellular stores. However, influx of calcium from the extracellular medium after endothelin-l stimulation was reduced in pericytes that had been cultured in 25 mM D-glucose. L-type Ca2+ currents were identified by patch clamping. The L-type Ca2+ channel agonist, (-)-Bay K8644, caused less influx of calcium from the extracellular medium in pericytes that had been cultured in 25 mM D-glucose than in those cultured with 5 mM D-glucose. However, 3-O-methylglucose, a nonmetabolizable analogue of glucose which can cause glycation, had similar effects to those of high concentrations of glucose. The results suggest that reduced function of the L-type Ca2+ channel that occurs in bovine retinal pericytes after culture in high concentrations of D-glucose is probably due to glycation of a channel protein.