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921.
R. Tala-Ighil M. Boumaour M.S. Belkaïd A. Maallemi K. Melhani A. Iratni 《Solar Energy Materials & Solar Cells》2006,90(12):1797-1814
In order to improve the solar cell conversion efficiency, a thin film of doped tin oxide (SnO2: F) has been deposited by the spray-pyrolysis technique on a monocrystalline diffused silicon wafer. Subsequently, the layer must undergo the firing step of screen-printed contacts with temperatures up to 830 °C. After annealing, one notices with the naked eye the appearance of speckles disturbing the uniformity of the as-deposited blue-coloured SnO2:F. Characterizations such as XPS, FTIR, RBS, XRD, SEM, Hall Effect, four point probe...etc, are all consistent to reveal a net increase of the SnO2:F layer resistivity which leads to efficiency degradation. Annealing the thin films under CO and 90% N2–10% H2 atmospheres was investigated to seek possibilities to preserve the expected improvements. Unlike forming gas, CO reducing ambient was found to be very effective for the high temperature contact firing with no thin film conductivity deterioration. 相似文献
922.
Tello M Rejzek M Wilkinson B Lawson DM Field RA 《Chembiochem : a European journal of chemical biology》2008,9(8):1295-1302
Understanding the structure and mechanism of sugar nucleotide processing enzymes is invaluable in the generation of designer enzymes for biotransformation, for instance, in connection with engineering antibiotic glycosylation. In this study, homology modelling and mechanistic comparison to the structurally related RmlC epimerase family has been used to identify and assign functions to active-site residues in the Tyl1a-catalysed keto-sugar nucleotide isomerisation process. Tyl1a His63 is implicated as the base that initiates the isomerisation process by substrate C-3 deprotonation, with Arg109 stabilising the resulting enolate. Subsequent O-3 deprotonation (potentially by His65) and C-4 protonation (potentially by Tyr49) complete the isomerisation process. 相似文献
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The PIROGAS process consists in replacing, in part or in total, the hot blast blown through the blast furnace tuyeres by reducing gas heated to a temperature of about 2000°C. The heating or the overheating and, eventually, the production of the reducing gas, can be achieved directly in the plasma heater. Up to 80% of the coke required for a conventional blast furnace operation can be replaced by substitute fuels. The PIROGAS process makes it possible to optimize the ratio between fossil fuels and electric power consumption to achieve an economic optimum. Trials carried out on an experimental blast furnace have shown that an operation with co'~e consumption as low as 105 kg of coke/ton of hot metal can be easily attained. Furthermore, it appeared during these trials that the quality of the hot metal can be instantaneously modified by appropriate action on reducing gas temperature and composition. Thus, the control of the process becomes easier and more rapid. Trials carried out on a full size commercial blast furnace have confirmed that the plasma heater in no way disturbs the operation of the blast furnace and, reciprocally, the unavoidable fluctuations in blast furnace operation do not perturb the functioning of the plasma heater. Plasma heaters have a high thermal efficiency (80%) and their electrical behaviour is excellent (power factor 0.92; no harmonics). 相似文献
928.
木质纤维素资源丰富,高效制取可利用的纤维素水解糖是实现其高附加值产品生产的关键,能够促进后续生物基产品的开发和产业化进程。预处理和水解糖化技术将木质纤维素转化为含有单糖的纤维素水解液,利用活性碳和离子交换等方法净化脱毒后的水解液再经浓缩、结晶等步骤最终可获得纤维素水解糖晶体。文章综述了木质纤维素水解糖制取中原料的预处理、水解糖化、净化脱毒和浓缩结晶等关键技术的最新研究进展,并展望了今后的发展趋势。 相似文献
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研究了乳酸精制过程中硫酸浓度、酸解温度对脱除总糖的作用,得出了酸解最佳工艺条件为:硫酸浓度98%,酸解温度为95℃,此时,残糖脱除率为96.2%。 相似文献
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