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751.
C_(22)-三元酸三酯的合成 总被引:1,自引:0,他引:1
C22-三元酸三酯的合成以棉籽油甲酯为原料,将非共轭的亚油酸甲酯在催化剂作用下转化成共轭亚油酸甲酯,同时与富马酸二酯发生D iels-A lder反应,生成C22-三元酸三酯。采用正交实验设计探讨了C22-三元酸的甲基二异戊酯的投料比、温度、催化剂用量、反应时间对合成反应的影响。富马酸二酯加入量按照富马酸二酯∶亚油酸甲酯(摩尔比)=1.1∶1投料,反应温度选择在200~210℃,催化剂碘的用量在0.6%,反应控制在2 h,最佳转化率相对于亚油酸甲酯可达96%。 相似文献
752.
A highly porous and absorbable crosslinked polystyrene, prepared by the concentrated emulsion polymerization method, was used as host polymer for the preparation of conducting, large objects, polymer composites. The composites, whose conductivity can be as high as 0.80 S/cm, were prepared by (i) imbibing the host polymer with a pyrrole (or oxidant) solution, (ii) partially drying the imbibed host polymer, and (iii) imbibing again with an oxidant (or pyrrole) solution for polymerization to take place. The electrical conductivity of the composite and the penetration of polypyrrole in the host polymer are influenced by the polymerization conditions (i.e., the concentrations of oxidant and pyrrole and the nature of the solvents used for the oxidant and pyrrole), the order in which the two imbibing solutions are introduced, and the drying time used after the first imbibation. The mechanical properties of the host polymer are improved with the incorporation of polypyrrole. Scanning electron micrographs of the composites indicate that the polypyrrole coats uniformly as a film the inside of the porous host polymer. 相似文献
753.
Hydrophobic–hydrophilic composite membranes, containing polystyrene as the dispersed phase and polyacrylamide as the continuous phase, have been prepared by the concentrated emulsion polymerization method. They are highly absorptive for methyl chloride, benzene, and toluene, but poorly absorptive for cyclohexane. The absorption from toluene–cyclohexane mixtures was found to increse with increasing temperature and toluene concentration and to decrease with increasing fraction of polyacrylamide in the composite. The absorption is controlled by diffusion. The permeation rate through the membrane, which was determined by the pervaporation method, exhibits similar trends with respect to temperature, concentration, and fraction of polyacrylamide as absorption does. Higher permeation was obtained by increasing the temperature and by increasing the toluene concentration or by decreasing the fraction of polyacrylamide. The selectivity which was in the range of 4–8 varies inversely with the permeation rate through the membrane which was in the range of 2 × 103?1.0 × 104 g/m2 h. 相似文献
754.
Catalytic Combustion 总被引:9,自引:0,他引:9
Increased awareness of the problems caused by air pollution and the decrease of fossil fuel reserves have resulted in great interest in combustion techniques that reduce pollutant emission levels from combustors while simultaneously increasing combustion efficiency. The development of catalytic combustors has two primary objectives: to attain levels of NOX emissions substantially below those possible with conventional ones, and/or to carry out stable combustion for low concentrations of fuel in air. 相似文献
755.
756.
共轭亚油酸粉末化微胶囊的制备 总被引:1,自引:0,他引:1
研究了喷雾干燥法制备共轭亚油酸微胶囊的工艺参数及配比条件。结果表明,最佳的工艺参数及配比条件为:乳液80℃热处理60 m in,乳化剂蔗糖酯加入量为水液的1%~1.5%,大豆分离蛋白与麦芽糊精质量比为1∶4,壁材中玉米糖浆含量38.5%,固形物含量16.7%,共轭亚油酸理论含量16%左右,进风温度130~150℃,进料流量(2.5~3.5)×150 mL/h,进料温度35℃,进风流量1.1 m3/m in左右,喷嘴压力180 kPa。制备出的共轭亚油酸微胶囊有较好的产品质量。 相似文献
757.
The complex formation between β-cyclodextrin and nitrophenol isomers was studied with the aid of reversed phase liquid chromatography. The effects of temperature, pH, and methanol content on the formation constants of the nitrophenol/β-cyclodextrin complexes were investigated. The complex formation constants were found to decrease with increasing temperatures. This decrease in formation constant was independent of the pH of the mobile phase. From the temperature dependence of the formation constants we were able to extract enthalpies and entropies of the complex formation. The values calculated in this work agree favorably with published values. Three pHs were examined: 3.57, 4.65, and 5.6. The formation constants of the ortho and meta isomers were highest at the lowest pH and leveled off at the two higher pHs. The para isomer showed a minimum in the formation constant at pH 4.65. This behavior was independent of the pH of the mobile phase. 相似文献
758.
Giray A. Birkan Jeffery L. Kennington Eli V. Olinick Augustyn Ortynski Gheorghe Spiride 《Telecommunication Systems》2006,31(1):61-83
Dense wavelength division multiplexing (DWDM) opaque networks use expensive optical/electrical/optical (O/E/O) conversion at each end of a fiber link. Several technological advances have
been used in an attempt to reduce the O/E/O conversion cost component: improved optical amplifiers using distributed Raman
amplification allow signals to traverse longer distances without amplification and/or regeneration; optical switches allow
the signal to remain in the optical domain most of the time. Networks that use this equipment to eliminate some of the O/E/O
conversions are called transparent or all-optical networks and benefit from reduced capital costs at the expense of operational costs and complexity in order to handle potential adjustments
in traffic demand. In this investigation, we develop optimization-based algorithms for DWDM network design and traffic routing
for both opaque and all-optical networks. This study compares the performance of AMPL/CPLEX implementations of both algorithms
on realistically sized networks with up to 36 nodes and 67 links. In all test cases considered the all-optical network design
is substantially less expensive than the traditional opaque network design with cost reductions in the range of 12% to 26%. 相似文献
759.
This article highlights the potential benefits and challenges related to implementation of IT-sup-ported strategic competence management as part of a human resource management system. A case study of the implementation of a competence management system in the global telecommunications company Ericsson reveals several implementation challenges, and also shows how the system supports Ericsson's knowledge networking strategy, through locating experts and stimulating emerging “communities of knowing.” 相似文献
760.
Purely Organic Thermally Activated Delayed Fluorescence Materials for Organic Light‐Emitting Diodes
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The design of thermally activated delayed fluorescence (TADF) materials both as emitters and as hosts is an exploding area of research. The replacement of phosphorescent metal complexes with inexpensive organic compounds in electroluminescent (EL) devices that demonstrate comparable performance metrics is paradigm shifting, as these new materials offer the possibility of developing low‐cost lighting and displays. Here, a comprehensive review of TADF materials is presented, with a focus on linking their optoelectronic behavior with the performance of the organic light‐emitting diode (OLED) and related EL devices. TADF emitters are cross‐compared within specific color ranges, with a focus on blue, green–yellow, orange–red, and white OLEDs. Organic small‐molecule, dendrimer, polymer, and exciplex emitters are all discussed within this review, as is their use as host materials. Correlations are provided between the structure of the TADF materials and their optoelectronic properties. The success of TADF materials has ushered in the next generation of OLEDs. 相似文献