The track etch rates of
1020
Ne-ion in cellulose nitrate (LR-115) have been measured for different temperatures and the activation energy is determined.
The experimental results show that both the track etch rate and the normalized track etch rate depend on the energy loss as
well as on etching temperature. The maximum etched track length of
1020
Ne-ion agrees with the theoretically computed range. The experimental results show that there is no sharp threshold, at least
in CN(LR-115). 相似文献
A wisely chosen geometry of micro textures with the favorable relative motion of lubricated surfaces in contacts can enhance tribological characteristics. In this paper, a computational investigation related to the combined influence of bearing surface texturing and journal misalignment on the performances of hydrodynamic journal bearings is reported. To this end, a numerical analysis is performed to test three texture shapes: square “SQ”, cylindrical “CY”, and triangular “TR”, and shaft misalignment variation in angle and degree. The Reynolds equation of a thin viscous film is solved using a finite differences scheme and a mass conservation algorithm (JFO boundary conditions), taking into account the presence of textures on both full film and cavitation regions. Preliminary results are compared with benchmark data and are consistent with a positive enhancement in misaligned bearing performances (load carrying capacity and friction). The results suggest that the micro-step bearing mechanism is a key parameter, where the micro-pressure recovery action present in dimples located at the second angular part of the bearing (from 180° to 360°) can compensate for the loss on performances caused by shaft misalignment, while the micro-pressure drop effect at the full film region causes poor performances. Considering the right arrangement of textures on the contact surface, their contours geometries can have a significant impact on the performance of misaligned journal bearings, particularly at high eccentricity ratios, high misalignment degrees and when the misalignment angle α approaches to or . 相似文献
In the present research, an effective on chip electromembrane extraction (CEME) coupled with high performance liquid chromatography was presented for analysis of nortriptyline (NOR) and amitriptyline (AMI) as basic model analytes from urine samples. The chip consists of two polymethyl methacrylate (PMMA) parts with two craved microfluidic channels in each part. These channels were used as flow path for the sample solution and a thin compartment for the acceptor phase. A porous polypropylene sheet membrane impregnated with an organic solvent was placed between two parts of chip device to separate the channels. Two platinum electrodes were mounted at the bottom of these channels that were connected to a power supply providing the electrical driving force for migration of ionized analytes from sample solution through the porous sheet membrane into the acceptor phase. This new setup provides effective and reproducible extractions with low volume of sample solution. Efficient parameters on CEME of the model analytes were optimized using one variable at a time method. Under the optimized conditions, the calibration curve was linear in the range of 10.0–500 μg L−1 with coefficient of determination (r2) more than 0.9902. The relative standard deviations (RSDs %) for extraction and determination of the analytes were less than 6.8% based on six replicate measurements. LODs less than 4.0 μg L−1 were obtained for both of the model analytes. The preconcentration factors higher than 17.0-fold were obtained. The results demonstrated that CEME would be used efficiently for extraction and determination of AMI and NOR from urine samples. 相似文献
A novel magnetic acidic catalyst comprising Preyssler (H14[NaP5W30O110]) heteropoly acid support‐ed on silica coated nickel ferrite nanoparticles (NiFe2O4@SiO2) was prepared. The catalyst was character... 相似文献
Poly-2-(2,3-dimethylanilino) benzoic acid (PMF) coatings on copper and brass alloy were synthesized by electrochemical oxidation of 2-(2,3-dimethylanilino) benzoic acid in the presence of oxalic acid as the reaction medium. Electrodeposition was carried out using the cyclic voltammetry technique using a silver/silver-chloride standard electrode, with a scan rate of 600 mV min–1. Smooth and well adhered PMF coatings were electrosynthesized during sequential scanning of the potential in the range–500 mV to 1400 mV on copper and brass alloy. The electrodeposited coatings were characterized by recording the oxidation peaks at 122 mV for Cu and–0.7 mV for brass, in cyclic voltammetry and using scanning electron microscopy (SEM). Corrosion inhibition efficiency of coated copper and brass alloy was investigated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques. The impedance results showed that the inhibition efficiency of coated copper is 89% and for coated brass 79.4% compared to the uncoated copper and brass in 0.1 M H2SO4.
Sofosbuvir (SOF) and ledipasvir (LED) are recently approved and coformulated as directly acting antiviral agents used for treatment of hepatitis C virus (HCV). A reversed phase high performance liquid chromatography - diode array detector (RP-HPLC/DAD) method was developed and validated for the first time for the analysis of newly formulated anti-HCV combination, in pure form, pharmaceutical formulation and in human plasma. In the developed method, separation was performed on Zorbax® Eclipse C18 column using a gradient mixture of acetonitrile–water as a mobile phase and scanning was performed at 260?nm (for SOF) and 330?nm (for LED). The two drugs were completely separated from each other and from plasma, where plasma peak appeared at 2.76?±?0.05?min, SOF at 4.25?±?0.05, and LED at 7.35?±?0.05. The developed method showed high sensitivity, the drugs showed linearity in the range of 1–45?µg/mL for both pure form and spiked human plasma. Three freeze–thaw cycles were performed separately at two different temperatures, ?8 and ?20°C. No significant loss of the studied drugs were observed during repeated thawing and freezing. Validation parameters such as accuracy, precision, robustness, and ruggedness were tested in compliance with USP recommendations, where acceptable results were obtained. Applying to pharmaceutical formulation showed no interference from tablet excipients. 相似文献