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1.
Pharmacodynamic Comparison of a Nasal Formulation of Verapamil and Intravenous and Oral Dosage Forms
The nasal route has been shown to be effective for the administration of numerous drugs in order to improve drug bioavailability. A nasal gel of verapamil hydrochloride was formulated and evaluated pharmacodynamically in humans, using electrocardiographic results, with comparison to oral and IV routes. Seven volunteers were involved in the study and the pharmacodynamic parameters were evaluated statistically. Experimental nasal gel showed similar pharmacodynamic results with the intravenous route, which is a hint to the reduction in verapamilinduced first-pass metabolism. However, oral route of administration showed a tendency of less efficacy. No reasonable effect of verapamil could be obtained with the placebo group. 相似文献
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The dispersive refractive index n(λ) and extinction coefficient k(λ) of CdS thin films were evaluated from spectrophotometric transmittance characteristic in the visible region. A method is presented to determine n(λ) and k(λ) in the region k2 n2, using wavelength and transmittance values. This method has been used for the investigation of the effect of the deposition rate on the optical properties of cadmium sulfide films. The refractive indices are found to depend on the deposition rate with values between 2.48 and 2.60. The energy gap of the samples is found to be independent of deposition rate with the value 2.44 eV. The real and imaginary parts of the dielectric constant have also been evaluated. 相似文献
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Plasma glow‐discharge application is known as a technique to coat or modify the surfaces of various materials. In this study, the influence of oxygen rf‐plasma treatment on surface and bulk properties of a biological polyester, poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate), were studied by determining water content and water contact angle, and by using X‐ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The plasma‐treated films absorbed more water than the untreated film, and the absorbance increased with the total power applied. The water contact angles decreased and O/C atomic ratio increased on treatment, indicating that the material became more hydrophilic due to increases in the oxygen‐containing functional groups on the surface of the polymer. A direct relation could be observed when the O/C ratio was plotted against the total power applied (treatment duration × treatment power). SEM revealed a visual record of surface modification, the extent of which increased with increased total power. It was thus possible to alter the surface chemistry and relevant properties of the polymer film using oxygen plasma as a tool. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1285–1289, 2003 相似文献
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In wind energy conversion systems, one of the operational problems is the changeability and discontinuity of wind. In most cases, wind speed can fluctuate rapidly. Hence, quality of produced energy becomes an important problem in wind energy conversion plants. Several control techniques have been applied to improve the quality of power generated from wind turbines. Pitch control is the most efficient and popular power control method, especially for variable-speed wind turbines. It is a useful method for power regulation above the rated wind speed. This paper proposes an artificial neural network-based pitch angle controller for wind turbines. In the simulations, a variable-speed wind turbine is modeled, and its operation is observed by using two types of artificial neural network controllers. These are multi-layer perceptrons with back propagation learning algorithm and radial basis function network. It is shown that the power output was successfully regulated during high wind speed, and as a result overloading or outage of the wind turbine was prevented. 相似文献
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Sevan Platin Elif Ö. Özer Ugur Akman Öner Hortaçsu 《Journal of the American Oil Chemists' Society》1994,71(8):833-837
Effects of temperature (at 35, 45 or 55°C) and pressure (10–110 atm) on the relative distribution coefficients of the twelve
key components of spearmint oil (essential oil ofMentha cardiaca; Scotch spearmint) at equilibrium in dense CO2 were investigated under conditions ranging from subcritical to supercritical regions. Effects of vapor pressure, molecular
weight and polarity of the key components on their equilibrium distributions in sub/supercritical CO2 are discussed. At 35°C, all key components of spearmint oil are equally soluble in dense CO2 within the 12–102 atm pressure region. At 45 and 55°C, the key components are equally soluble for pressures greater than
about 60 atm. However, around either 45°C/27 atm or 55°C/35 atm conditions, the relative distribution coefficients of all
monoterpene hydrocarbons and of isomenthone (an oxygenated monoterpene) exhibit maxima, which are due to significantly higher
vapor pressures of these components and significantly lower solvating power of the dense-gas solvent at these particular temperatures
and pressures. Vapor-pressure effects, coupled with the decrease in solvating power, dominate the effects of polarity and
molecular mass of the key components. Deterpenation of spearmint oil with dense CO2 is possible around either 45°C/27 atm or 55°C/35 atm, where the monoterpene hydrocarbons tend to concentrate in the CO2-rich phase. 相似文献
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Metal spinning is a plastic forming process in which a disk or tube of metal is rotated at high speed and forced onto a mandrel. It is widely used in industry as an efficient, modern and economical production technique. This research proposes to develop a versatile robotic forming method and expand the application areas of robotic manufacturing processes to the metal spinning area. A lathe-type laboratory setup has been built and an industrial robot manipulator has been used to implement the metal spinning process. Experiments have been conducted with enhanced cascaded trajectory tracking algorithms with an add-on vibration suppressor. The potential of the proposed method has been illustrated with extensive case studies using both constant and variable speed trajectory profiles. Analyses for the growth of wrinkles have been performed through the topographical measurements of the products and the forming forces have been inspected. Results indicate that the efficiency of the process can be significantly improved with suitably selected variable speed trajectory profiles and the process parameters. The developed scheme successfully reduces the excessive oscillations of the manipulator during the metal spinning process and it requires no additional hardware to employ. The investigations demonstrate the feasibility of robotic metal spinning using an industrial serial link manipulator. 相似文献
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Powder Metallurgy and Metal Ceramics - In this study, different heat treatment regimes, such as sintering, sintering with low-pressure cementation, and only low-pressure cementation were applied to... 相似文献