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Notes: —The effect of 1-hydroxy-3-aminopyrrolidone-2(HA-966), a CNS depressant, was studied on the metabolism of [14C]glucose and [3H]acetate in the brain in mice. HA-966 had a marked effect on glucose metabolism. The conversion of glucose carbon into amino acids associated with the tricarboxylic acid cycle (‘cycle’) was severely reduced, while the concentration of brain glucose was approximately doubled. Relative to the specific radioactivity of glucose in the brain, the specific radioactivity of alanine was 60–70 per cent of the control, indicating a reduction in the rate of glycolysis, and those of the‘cycle’amino acids were also lowered. A reduction in‘cycle’flux of 30–35 per cent was estimated. It was established that the depressed glucose utilization flux was not due to either impaired uptake of glucose from blood to brain or to hypothermia. In contrast to [14C]glucose, there was no change in the labelling of the amino acid fraction from [3H]acetate, which is preferentially metabolized in the 'small’compartment believed to be associated with glia. Thus it seems that CNS depression caused by HA-966 resulted in a selective decrease in energy production in the‘large’metabolic compartment where glucose is oxidized preferentially and which is believed to be associated with neuronal structures.The results also suggested that communication between the metabolic compartments mediated via glutamine and GABA was reduced, since the labelling from [3H]acetate of glutamine was increased and that of GABA decreased by HA-966.

Notes: Abstract— Thiamine deficiency produced by administration of pyrithiamine to rats maintained on a thiamine-deficient diet resulted in a marked disturbance in amino acid and glucose levels of the brain.In the two pyrithiamine-treated groups of rats (Expt. A and Expt. B) there was a significant decrease in the levels of glutamate (23%, 9%) and aspartate (42%, 57%), and an increase in the levels of glycine (26%, 27%) in the brain, irrespective of whether the animals showed signs of paralysis (Expt. A) or not (Expt. B). as a result of thiamine deficiency. A significant decrease in the levels of γ-aminobutyrate (22%) and serine (28%) in the brain was also observed in those pyrithiamine-treated rats which showed signs of paralysis (Expt. A). Threonine content increased by 57% in Expt. A and 40% in Expt. B in the brain of pyrithiamine-treated rats, but these changes were not statistically significant.The utilization of [U-14C]glucose into amino acids decreased and accumulation of glucose and [U-14C]glucose increased significantly in the brain after injection of [U-14C]glucose to pyrithiamine-treated rats which showed abnormal neurological symptoms (Expt. A). The decrease in 14C-content of amino acids was due to decreased conversion of [U-14C]glucose into alanine, glutamate, glutamine, aspartate and γ-aminobutyrate. The flux of [14C]glutamate into glutamine and γ-aminobutyrate also decreased significantly only in the brain of animals paralysed on treatment with pyrithiamine.The decrease in the labelling of, amino acids was attributed to a decrease in the activities of pyruvate dehydrogenase and α-oxoglutarate dehydrogenase in the brain of pyrithiamine-treated rats. The measurement of specific radioactivity of glucose, glucose-6-phosphate and lactate also indicated a decrease in the activities of glycolytic enzymes in the brain of pyrithiamine-treated animals in Expt. A only. It was suggested that an alteration in the rate of oxidation in vivo of pyruvate in the brain of thiamine-deficient rats is controlled by the glycolytic enzymes, probably at the hexokinase level.The lack of neurotoxic effect and absence of significant decrease in the metabolism of [U-14C]glucose in the brain of pyrithiamine-treated animals in Expt. B were probably due to the fact that animals in Expt. B were older and weighed more than those in Expt. A, both at the start and the termination of the experiments.

Notes: The application of surface specific X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) will be shown to be an effective means for the elucidation of hair fiber surface chemistry and structure. Example studies of bleaching and fiber conditioning treatments are discussed. The bleached fiber surface is found to become more hydrophilic due to the loss of the naturally occurring hydrocarbon overlayer and oxidation of surface functional groups as a result of bleaching. Comparison between generic bleaching regimens illustrates the importance of increased pH and the presence of surfactant for effective treatment. Adsorption of conditioning diester quat and dimethicone molecules reintroduces a hydrophobic like surface layer on the hair fiber. Spectroscopic data indicate a segregated adsorption structure of the chemically different conditioning molecules. Electron microscope images of the conditioned hair show a smooth uniform surface.

Notes: The shift of the volume plasmon energy with particle size in cadmium sulphide nanoparticles was examined by energy filtered transmission electron microscopy. This technique allowed the plasmon energy of individual, well-separated particles to be measured. The measured plasmon energy was found to increase with decreasing particle size, in general agreement with the theoretical approximation for plasmon shifting due to the quantum size effect. The nanoparticle diameters ranged between 1.5 and 3.8 nm and they were prepared by mechanochemical processing techniques and then electrophoretically deposited on the transmission electron microscope specimen grids. © 1999 American Institute of Physics.

Notes: InSb enhancement-mode, metal-insulator-semiconductor, field-effect transistors with 1 μm gate lengths have been fabricated. When operated at room temperature with less than 0.5 V applied between the source and drain, the transistors have a static dynamic range in excess of 20 dB, a cut-off frequency (fT) of 14 GHz and a transconductance, at 1 GHz, of 230 mS mm−1. Analysis of the parasitic capacitances indicates an intrinsic fT of about 90 GHz. The static electron mobility in the channel is 2×104 cm2 V−1 s−1, so a carrier velocity of about 3.7×107 cm s−1 should be attained. This leads to a predicted frequency response of 84 GHz, in reasonable agreement with the intrinsic microwave data.

Notes: Stimulated emission at 5.1 μm was demonstrated from a broad area In1−xAlxSb/InSb heterostructure diode laser grown by molecular beam epitaxy. For a 5 μs pulse and a 500 Hz repetition rate the threshold current density was 1480 A cm−2 at 77 K and the maximum operating temperature was 90 K at a current density of 2680 A cm−2. Maximum peak power output was estimated to be 28 mW per facet at 77 K and 4500 A cm−2.