The electroless plating of a cobalt layer containing tungsten onto a copper substrate was investigated, using hydrazine as a reducing agent. The plating reaction was initiated by placing a strip of ...aluminium foil in contact with the substrate in the plating bath. Under optimized conditions, a uniform cobalt layer containing 0.9% tungsten was deposited with a deposition rate of 1.6μm h−1. As the concentration of tungstate in the plating bath was increased, the tungsten content of the resulting cobalt layer increased while the deposition rate decreased.
An accumulation of recent evidence suggests that the mechanism in ischemic preconditioning (IPC) may involve the activation of protein kinase C (PKC) regulatory pathway. In this study, we examined ...whether the content of 1,2-diacylglycerol (1,2-DAG) and ceramide, which are intracellular second messengers regulating PKC activity, change during IPC in isolated perfused rat hearts, and whether the observed change in 1,2-DAG is accompanied with alteration in its fatty acid composition. Hearts subjected to IPC, consisting of 5-min transient global ischemia followed by 5-min reperfusion, presented a significant functional recovery during subsequent 40-min reperfusion following 40-min global ischemia compared with non-preconditioned hearts. An increase in 1,2-DAG content was observed in hearts subjected to 5-min transient ischemia compared with non-ischemic control hearts, however this was not seen in hearts harvested after 5-min reperfusion following 5-min ischemia. While fatty acid composition in 1,2-DAG was virtually unchanged in hearts subjected to 5-min ischemia, saturated 1,2-DAG decreased and monounsaturated/polyunsaturated 1,2-DAG increased in hearts reperfused for 5-min following 5-min ischemia compared with the non-ischemic control hearts. Ceramide mass did not change significantly, suggesting that the contribution of ceramide may be small in IPC. These data are in concert with the hypothesis that 1,2-DAG is a second messenger in IPC and the changes in fatty acid composition of 1,2-DAG may add new insight concerning signal transduction pathway in IPC.
We report on an investigation of commensurability oscillations in antidot square-lattices, and show that the commensurate peaks in resistivity ρxxderive from two kinds of electron: runaway and ...quasipinned electrons. The runaway electrons, which skip away along the antidot arrays, increase the value of conductivity σxx; and the quasipinned electrons, which orbit some antidots for a long time, decrease the value of σxx. Therefore, by competition between the two different types of electron, the conductivity σxxis determined. The conductivity σyxin the antidot lattice always has dips at the peaks in ρxx. As a result, by combining the of values of σxxand σyx, the resistivity is determined through the orthodox relation of ρxx= σxx/ (σxx2 + σyx2).
We pharmacologically investigated the potential involvement of nitric oxide (NO), prostacyclin, adenosine, adenosine triphosphate (ATP)-sensitive K (K(ATP)) channel opening and Ca2+-activated K ...(K(Ca)) channel opening in coronary vasodilatation during 15 min of hypoxia in isolated rat hearts perfused at a constant pressure of 70 mm Hg. The coronary flow suppressed by 10(-4) M Nomega-nitro-L-arginine methyl ester (L-NAME), which corresponds to the NO-dependent flow, decreased to almost zero during hypoxia. In contrast, the NO-dependent coronary flow amounted to approximately 40% of the total coronary flow during normoxia. The suppression of coronary flow by 10(-5) M 8-phenyltheophylline (8-PT), which corresponds to the adenosine-dependent flow, was remarkable in the middle and the late phases of a 15-min hypoxia. The coronary flow suppressed by 2 x 10(-6) M glibenclamide, which corresponds to the K(ATP) channel opening-dependent flow, depended on the agents added to the perfusate. However, there was a marked increase in coronary flow in the early phase of hypoxia in the heart perfused with the combination of 8-PT, 10(-2) M tetraethylammonium (TEA) and L-NAME. During hypoxia, the coronary flow suppressed by TEA, which corresponds mainly to the K(Ca) channel opening-dependent flow, also depended on the agents added to the perfusate. However, during reoxygenation, there was a transient significant increase in any combination of the agents. Our study suggests that hypoxia almost completely inhibits NO production, and that K(ATP) channel opening immediately after hypoxia and subsequent enhanced adenosine production cause a marked hypoxic coronary vasodilatation. It also suggests that K(Ca) channel opening causes vasodilatation during reoxygenation.
Radionuclide angiography with technetium-99m hexamethylpropylene amine oxime (99mTc-HMPAO) or technetium-99m ethyl cysteinate dimer (99mTc-ECD) enables the non-invasive estimation of absolute ...cerebral blood flow (CBF) to be determined by using spectral analysis (SA). We previously demonstrated the clinical use of SA; however, this method involves a few manual steps. The aim of this study was to evaluate the interobserver variability of CBF estimations made using SA and compare these results with those obtained by using graphical analysis (GA). In twenty patients with various brain diseases (27-74 years old), radionuclide angiography examinations were performed using 99mTc-labeled compounds (10 patients, 99mTc-HMPAO; 10 patients, 99mTc-ECD). Bilateral cerebral hemispheres were studied in all patients, and the brain perfusion index (BPI) values were estimated using SA and GA. The interobserver variability between two observers was then assessed. A good correlation between the BPI values assessed using both SA (BPI(S)) and GA (BPI(G)) was obtained. The correlation coefficient for BPI(S) (r = 0.987) was almost the same as that for BPI(G) (r = 0.982). The degree of interobserver variability was not affected by the measurement of elevated BPI values. Measurements carried out by two observers using both SA and GA exhibited a similar degree of interobserver variability. SA appears to have a satisfactory interobserver variability and may be more suitable for clinical applications.
The intensity and decay profile of the photoluminescence (PL) in glassy GeSe2 are measured as a function of temperature from 2 to 200 K. The intensity decreases exponentially in the temperature ...region > 100 K. The complicated temperature dependence of the decay profile as well as the dependence of the intensity are explained in a unified framework by adopting a model of the luminescent sites whose thermal activation energy for the nonradiative process is distributed. Authors show that the intensity variation is affected by the nonradiative process while the decay life time depends almost only on the radiative transition rate. 5 refs.
Potentiostatic cathodic electrodeposition of CdTe compound on a gold-plated substrate was studied at 70ºC using new acidic aqueous electrolytic baths (pH3.0) containing citric acid. The composition ...of the deposits was controlled by changing the deposition potential, which depended on the concentrations of Te(IV) and citrate. The stoichiometric CdTe layers obtained were polycrystalline, having a uniform surface morphology without pinholes. In the presence of citrate ions, the solubility of tetravalent tellurium species in the citrate bath at pH3.0 was more than 10mM, which was about one or two orders higher than that in conventional acidic sulfate baths. The increase in the solubility will be accounted for by a complexation between Te(IV) and citrate ions, which has not been reported so far. A set of linear sweep cathodic voltammograms for Te(IV)-citrate baths suggested the presence of the complex.
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