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排序方式: 共有2609条查询结果,搜索用时 15 毫秒
961.
M. Bououdina Y. Oumellal L. Dupont L. Aymard H. Al-Gharni A. Al-Hajry T.A. Maark A. De Sarkar R. Ahuja M.D. Deshpande Z. Qian A.B. Rahane 《Materials Chemistry and Physics》2013
In this study, amorphous TiNi phase was successfully prepared using mechanically milling for a very short time of 8 h. HRTEM confirms the formation of amorphous phase with the presence of nanocrystalline Fe particles. After hydrogenation (30 bars of H2 for a duration of 2 h), the electrochemical reaction shows that TiNi hydride/Li cell discharges at a current of one Li for 10 h between 3 V and 0.005 V. The discharge of TiNiH electrode around x = 1 Li corresponds to a capacity of 251 mAh g−1 and a hydride composition of TiNiH1.0 at an average voltage of 0.4 V. Ex-situ X-ray diffraction pattern collected at the end of the discharge shows a mixture of amorphous TiNi compound and LiH. A general mechanism for the electrochemical reaction is then proposed: α-TiNiH + Li+ + e− → α-TiNi + LiH. The results from DFT calculations yield an average cell voltage of 0.396 V, which is in good agreement with the experimental pseudo-plateau occurring at 0.4 V. 相似文献
962.
Liang Wu Yuehui He Ting Lei Bo Nan Nanping Xu Jin Zou Baiyun Huang C.T. Liu 《Materials Chemistry and Physics》2013
The hydrogen evolution reactions on porous Ni3Al electrodes, as well as their electrochemical properties in 6 M KOH solutions have been investigated by the polarization measurement, cyclic voltammetry and EIS technique. Results show that the porous Ni3Al electrodes with lower pore size possess higher catalytic activity for hydrogen evolution in KOH solutions. Their stability in 6 M KOH at 298 K and 358 K under the condition of the reverse polarization is shown to be very good. The electrodes exhibit long term stability and retain high catalytic performance under industrial conditions. 相似文献
963.
In this work, Si80Ge20P2 alloys were fabricated by mechanical alloying (MA) and spark plasma sintering (SPS). SiO2 and ZrO2 were taken as milling media respectively to investigate the effect of milling media on the fabricating process and the thermoelectric properties of SiGe alloys. The results show that, compared with the zirconia ball, though the agate one contains less kinetic energy, the solid solution of SiGe taken it as the milling media forms more quickly and at the same time has smaller average grain size through the whole milling time. The solid solution of Ge to Si crystal of samples under ZrO2 media remains stably around 98% and is much higher than that of specimens with agate as the media. In the sintering process, the previous application of ZrO2 easily causes the enrichment of elementary P and the loss of Si and leads to serious deviation from the original stoichiometric proportion of the compounds which is beneficial to the following machining and finally does harm to the thermoelectric properties of the Si80Ge20P2 alloys. 相似文献
964.
《Drug development and industrial pharmacy》2013,39(7):599-612
The factors affecting powder mixing are reviewed. Methods of analyzing a random mix are discussed (indices, the Poisson distribution, and analyses of variance [ANOVA]). The influence of particle size, shape, and density are described, along with scale of scrutiny and sampling. Segregation and agglomeration are major problems in powder mixing, and their prevention and minimization are therefore paramount. Ordered mixing reduces segregation, but also introduces other problems. Regulating the particle size of the drug and altering particle shape minimizes segregation and agglomeration. 相似文献
965.
《Drug development and industrial pharmacy》2013,39(6):573-580
GI197111X is a 5‐alpha reductase inhibitor for the treatment of androgenetic alopecia. Equilibrium solubilities of GI197111X were determined in multiple solvents or cosolvents. A polymorph screen was conducted using suspension equilibration and solution recrystallization methods. Single crystals were grown from pyridine/water and crystal structure was determined using a Bruker SMART diffractometer. Crystal structure data were imported into Cerius2 to provide visualization of the crystal structure and calculation of the simulated X‐ray powder diffraction (XRPD) pattern. The solubility of GI197111X was low at 25°C in all vehicles suitable for animal and human dosing. The solubility of 6.4 mg/mL in Capmul MCM made it the only choice for a soft gel dosage form for phase I/II. Solution recrystallization and suspension equilibration of GI197111X have produced only one crystal form. Crystal structure data: orthorhombic P21 21 21; a?=?10.8960(6) Å, b?=?11.5683(6) Å, c?=?20.9019(11) Å; unit cell volume 2634.65(24) Å3; Z?=?4; calculated density?=?1.248 g/cc. The molecule has seven chiral centers, and single‐crystal analysis eliminated all possible stereoisomers except the expected conformation or its enantiomer. Hydrogen bonds occur from both carbonyl oxygens to an H–N group. Simulated vacuum‐based crystal morphology (habit) calculated using the Bravais–Friedel–Donnay–Harker, Growth Morphology, and Hartman‐Perdok modules in Cerius2 was a close match to the morphology observed by light microscopy. 相似文献
966.
A. Khorsand Zak W.H. Abd. Majid M.R. Mahmoudian Majid Darroudi Ramin Yousefi 《Advanced Powder Technology》2013,24(3):618-624
Zinc oxide nanoparticles (ZnO–NPs) were synthesized via the sol–gel method in starch media. Starch was used as a stabilizer to control of the mobility of zinc cations and then control growth of the ZnO–NPs. Because of the special structure of the starch, it permits termination of the particle growth. Thermogravimetry analysis (TGA) was applied on dried gel to obtain the certain calcination temperature(s) of the ZnO–NPs. The dried gel was calcined at different temperatures of 400, 500, and 600 °C. Several techniques such as X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR), and high-magnification transmission electron microscopy (TEM) were used to characterize the ZnO–NPs. The ZnO–NPs calcined at different temperatures exhibited a hexagonal (wurtzite) structure with sizes from 30 to 50 nm. The optical properties of the prepared samples were investigated using UV–vis spectroscopy. The results showed that starch is a suitable stabilizer in the sol–gel technique, and this method is a reasonable and facile method to prepare ZnO–NPs for large-scale production. 相似文献
967.
A.Y. Kandeil J-P.A. Immarigeon W. Wallace M.C. de Malherbe 《Materials at High Temperatures》2013,30(4):201-207
Some means by which the grain size and flow strength of nickel-base superalloy powder .compacts can be controlled during processing have been examined. The compacts were prepared by hot isostatic pressing and their flow behaviour studied by constant true strain rate compression testing under conditions simulating isothermal forging. It was found that the selection of a finer starting powder results in slight lowering of flow strength at forging temperatures. Prior cold working of the compact by hydrostatic extrusion also leads to small reductions in strength at these temperatures. Both the . grain size and flow strength may change substantially during plastic deformation at forging temperatures. This depends on the conditions of strain rate and temperature. Under all the testing conditions examined this transient flow behaviour is followed by a stesdy state regime of flow during which neither the grain size nor the flow strength continue to change. These observations and their practical implications are discussed. 相似文献
968.
Spouted bed drying of milk–blackberry pulp mixture at different ratios (V/V) was analyzed in this work. The effects of addition of adjuvant (maltodextrin, casein, and palm oil) in the milk–blackberry mixture and maltodextrin in the pure blackberry pulp were analyzed focusing on enhancing powder production efficiency. The best results were obtained for the paste composition of 25% concentrated milk–75% blackberry pulp (V/V) without addition of adjuvant, yielding stable fluid dynamic behavior, powder production efficiency greater than 60%, linear powder production kinetics, high anthocyanin content, and low final moisture content of the powder (3.08% wb). 相似文献
969.
Process control of a spray dryer that is usually used as the last step of production is very crucial in obtaining a quality standard product. To this end, predicting the effect of various operating and environmental parameters on product properties is essential. Modeling has been done in microscopic and macroscopic scales by modifying the mass and heat transfer equations used in investigating the drying mechanism. However, as far as momentum transfer is concerned, the equations are the same as the ones used in the available literature models. Unlike conventional models that take only the two streams of hot air and sprayed droplets into account, a third stream is considered in our proposed model and this modification improves the results significantly. The model equations have been solved numerically and new simulation software has been developed using Visual C++ 6.0. The model results are in good agreement with industrial data obtained from a detergent-producing plant and show maximum errors of about 10%. 相似文献
970.