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921.
922.
923.
Nano-porous Composites Based on Heteropolyacid Functionalized Ionic Liquid: Synthesis,Characterization, and Catalytic Performance in Esterification
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Functionalized ionic liquid samples (bmim-PW12) were synthesized by 1-butyl-3-methyl-imidazolium bromide (bmimBr) and 12-phosphotungstic heteropolyacid (PW12). The sam-ples were annealed at 100-450 oC and were characterized by Fourier transform infrared spec-troscopy, X-ray diffraction, scanning electron microscope, thermal gravity-DTG, brunauer emmett teller, and NH3-temperature programmed desorption. The results showed that the bmim-PW12 samples were crystal and maintained intact Keggin structure. The organic parts of those samples were partly decomposed at a temperature more than 350 oC. The sample annealed at 400 oC exhibited nano-porous structure, strong acidity, and excellent catalytic activity on the esterification of n-butanol with acetic acid. The higher ester yield was ob-tained when the mass ratio of catalyst over the reactants amount was 5% for bmim-PW12 catalyst annealed at 400 oC. 相似文献
924.
Youbao Wan Junhao Chu Shaoling Guo Lingxian Bo Tianyan Yu Bingkun Yu 《International Journal of Infrared and Millimeter Waves》2001,22(1):197-205
The potassium lithium niobate crystals have been grown up. The shapes of solid-melt interfaces which maintaining the steady growth of the potassium lithium niobate crystals have been described. The optical transmission spectrum of the crystal has been surveyed. The perfected crystals showed good Second Harmonic Generation properties. 相似文献
925.
H. Jory D. Wagner M. Blank S. Chu K. Felch 《International Journal of Infrared and Millimeter Waves》2001,22(10):1395-1407
A microwave system is described which allows testing of the quasi-optical mode converter in a gyrotron, which is completely assembled except for the attachment of the electron gun. Test results are presented for a TE6,2,1 gyrotron, and a similar design for a TE28,7,1 gyrotron is shown. 相似文献
926.
Enhanced fatigue property of PZT thin films using LaNiO3 thin layer as bottom electrode 总被引:2,自引:0,他引:2
X.J. Meng J.L. Sun J. Yu G.S. Wang S.L. Guo J.H. Chu 《Applied Physics A: Materials Science & Processing》2001,73(3):323-325
A highly (100)-oriented metallic LaNiO3 film was prepared directly on a Si substrate by a simple metalorganic decomposition (MOD) technique using lanthanum nitrate
and nickel acetate as the starting sources. Subsequent Pb(Zr,Ti)O3 (PZT) thin films deposited on the LaNiO3-coated Si substrate were obtained by a modified sol–gel method. It was found that the PZT thin films began to form a single
perovskite phase at a low annealing temperature of 530 °C, and exhibited highly (100) orientation. A ferroelectric capacitor
of Pt/Pb(Zr,Ti)O3/LaNiO3/Si annealed at 600 °C displayed a good P-E hysteresis characteristic and was fatigue-free even after 1011 switching cycles.
Received: 25 May 2000 / Accepted: 9 August 2000 / Published online: 30 November 2000 相似文献
927.
Investigation has been carried out on the thermal performance of sintered miniature heat pipes with 3 mm outer diameter.
In the theoretical analysis, the influence of wick structure parameters is determined by using the theory of capillary limitation.
As a result, the degree of importance is found to be as follows: porosity, powder diameter and thickness of wick structure.
In the experiments, heat pipes with sintered dendritic copper powder wicks were fabricated and tested. The maximum heat transfer
rate is about 13 W with an effective heat pipe length of 20 cm. By adopting the formulae developed for both sintered spherical
powder and fiber and adjusting their proportion, the agreement between experimental results and prediction is found to be
quite good in the tested operation temperature range.
Received on 26 February 2001 相似文献
928.
The relationship between the transported ion current and the cathodic arc current is determined in a vacuum arc plasma source equipped with a curved magnetic filter. Our results suggest that the outer and inner walls of the duct interact with the plasma independently. The duct magnetic field is a critical factor of the plasma output. The duct transport efficiency is to maximize at a value of bias plate voltage in the range +10 V to +20 V, and independent (within our limit of measurement) of the magnetic field strength in the duct. The plasma flux is composed of two components: a diffusion flux in the transverse direction due to particle collisions, and a drift flux due to the ion inertia. The inner wall of the magnetic duct sees only the diffusion flux while the outer wall receives both fluxes. Thus, applying a positive potential to the outer duct wall can reflect the ions and increase the output current. Our experimental data also show that biasing both sides of the duct is more effective than biasing the outer wall alone. 相似文献
929.
Theory of the coherent-mode decomposition of laser beams is proposed. The new model for the flat-topped beams proposed by Li recently is taken as an example. The analytical expressions for the M^2-factor and mode coherence coefficients of flat-topped beams have been derived in the rectangular coordinate system, by means of which the mode correlation, mode structure, and coherent-mode decomposition of flat-topped beams can be analysed. 相似文献
930.
假定二元液态混合物分子间的相互作用势能可以表示成多体相互作用势能的和,分子间的力为短程力,相互作用势能只与分子间的相对距离有关.利用分布函数理论导出了二元液态混合物的过剩内能和内压的公式.二元液态混合物的过剩内能和内压可以表示成体积的幂级数形式,其中的系数可以用多体相互作用势和多体径向分布函数表出.讨论了单元液体的内压和过剩内能的表达式,在两种特殊情形下,过剩内能和内压的表达式分别与Egelstaff的微扰论结果及Frank的实验结果具有相同的形式.讨论了二元混合物内压和内能的两个特例,其一,在特殊情形下,给出了混合液体过剩内能的混合规则的一个证明.其二,给出的二元混合物的过剩内能和内压的表达式与Frank的实验结果具有相同的形式. 相似文献