Silicon nitride film was deposited on silicon by gas phase reaction between SiH4 and NH3 using N2 as the carrier gas and a horizontal resistance-heated furnace at the temperature range of 650 to 950°C. The higher the substrate temperature became, the larger the wave number of the infrared, which corresponds to the maximum absorption. Film deposited at lower temperature always showed the hysteresis of C-V curve, but it almost disappeared by elevating substrate temperature and supplying much amount of ammonia. MNS diode was very stable to the BT-treatment even if it was intentionally contaminated with NaOH. Interface charge density was nearly 1.5×1012e/cm2 which was little dependent of surface treatments before depositing the film, and seemed to be almost determined by the positive charge in nitride film. C-V curve of the diode showed the frequency dependence, which was due to the accumulation of electrons in nitride film near the interface.
SUMMARYCardiac energy metabolism of pressure-overloaded rat hearts was examined under in vivo and in vitro conditions. Two, 4 and 6 weeks after constriction of the abdominal artery, the hemodynamic and metabolic profiles of hearts in vivo and of perfused hearts were determined. Significant increases in left ventricular weight/body weight (30 to 45% increase relative to the sham group), systolic and diastolic blood pressure (22 to 33% increase) and pressure-rate product (31 to 33% increase) were observed 2, 4 and 6 weeks after the operation, and a slight but significant decrease in heart rate was observed at 2 weeks after the operation. Tissue hydroxyproline content increased (17 to 93%) with time after pressure-overload. These findings are indicators of pressure-overloaded cardiac hypertrophy. The total high-energy phosphates of the in vivo rat myocardium under artificial respiration were lower than those of sham-operated rat myocardium 2 (23%) and 4 weeks (21%), but not 6 weeks after aortic constriction. The maximal oxygen consumption rates of mitochondria, when determined in the skinned cardiac fibers, also decreased 2 (47%) and 4 weeks (36%), but reversed 6 weeks after pressure-overload. However, the myocardial ATP, a utilizing form of high-energy phosphate, of pressure-overloaded rat myocardium remained normal at all times after cardiac hypertrophy. This suggests that alterations in hemodynamic variables of in vivo pressure-overloaded rats may not be attributable to a reduction in the myocardial energy production. In the perfused hearts isolated from pressure-overloaded rats, tissue ATP levels were similar to those of sham-operated rats, although the tissue creatine phosphate tended to be reduced in the pressure-overloaded animals at all stages of cardiac hypertrophy examined. Only a marginal decrease in the tissue high-energy phosphate (13%) was observed 4 weeks after the operation relative to that of sham-operated rats. In contrast, the developed tension of the perfused pressure-overloaded rat hearts was consistently lower (27 to 36%) than
The synthesis of 3,4‐methylenedioxymethamphetamine(MDMA), a serotonergic neurotoxin, labeled with tritium is described. Labeling was accomplished by N‐alkylation of the free base of the corresponding desmethyl compound using [3H]methyl iodide. The compound was purified by preparative HPLC. The radiochemical yield was about 60% based on [3H]methyl iodide. The radiochemical purity was more than 95% from HPLC and TLC. Furthermore, S(+)‐ and R(‐)‐[3H]MDMA were completely separated by analytical HPLC with chiral column.
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