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排序方式: 共有1063条查询结果,搜索用时 15 毫秒
91.
Xiang XuFangzhong Wang Yihui LiuJian Pu Bo Chi Li Jian 《Journal of power sources》2011,196(22):9365-9368
Solution impregnated La0.8Sr0.2Co0.8Ni0.2O3 + Gd-doped CeO2 (LSCN + GDC) cathodes for intermediate temperature solid oxide fuel cells (IT-SOFC) are prepared and their electrochemical properties are evaluated and compared with the conventional LSCN cathodes. The results indicate that the cathode performance can be enhanced by the presence of the nanosized microstructure produced with the solution impregnation method. It is determined that the amount of LSCN loading in the LSCN + GDC composite cathode needs to be higher than 35 wt% in order to achieve a performance superior to that of the conventional LSCN cathode. The optimum amount of LSCN loading is in the range of 45-55 wt% with an activation energy near 1.32 eV for oxygen reduction. At temperatures between 600 and 750 °C, the polarization resistance of the 55 wt% LSCN loaded LSCN + GDC cathode is in the range of 1.07 and 0.08 Ω cm2, which is only about one half of that for the conventional cathode. 相似文献
92.
High surface area MoO2/MgO was prepared by the reaction of MgO (250–300 m2 g−1) with a slurry of ammonium heptamolybdate in methanol or anhydrous ethanol at the alcohol boiling point. The low solubility
of ammonium heptamolybdate was sufficient for its gradual transport to the support surface: molybdena species were deposited
and ammonia was evolved. Catalytic activities in the hydrodesulphurization of benzothiophene of the MoO3/MgO samples were comparable to the activity of the reference commercial MoO3/Al2O3 catalyst.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
93.
Giampaolo Blanda Lorenzo Cerretani Alessandra Bendini Andrea Cardinali Giovanni Lercker 《European Food Research and Technology》2008,227(1):191-197
Nectarines (Prunus persica L. cv. Maria Laura) were manually selected, cut in slices and divided into four groups: fresh, untreated frozen, soaked in osmotic solution
and subsequently frozen, and vacuum impregnated (VI) and subsequently frozen. This investigation was focused on evaluation
of consumer acceptance with respect to treated versus untreated frozen nectarine slices. In a preliminary acceptance test
of untreated frozen nectarine slices, fruits were generally rejected on the basis of a darkened appearance and “oxidized”
taste. These negative attributes were probably linked to the activity of polyphenol oxidase (PPO) and depletion of phenols
due to cell rupture during freeze–thaw procedures. For these reasons, in order to evaluate the tendency of fruit to oxidation,
several analyses were performed: the antioxidant capacity of phenolic fraction and the o-diphenol content were estimated by spectrophotometric assays, whereas the hydroxycinnamic acid (chlorogenic and neochlorogenic
acids) composition was evaluated by high performance liquid chromatography (HPLC). Phenolic content and antioxidant capacity
were found to correlate well with the acceptance level of frozen nectarine slices. In this regard a higher phenolic content
associated with a higher acceptance level of nectarine samples. 相似文献
94.
M. Zdražil 《Catalysis Letters》1994,27(3-4):337-344
A new slurry impregnation method (SIM) of the preparation of a catalyst or catalyst precursor MoO3/Al2O3 is described. Aqueous slurry of powdered MoO3 is mixed with alumina extradátes and the mixture is refluxed. A low solubility of MoO3 is sufficient for transport of MoO3 from powder form via solution to the surface of the support. The catalysts were tested by hydrodesulfurization of thiophene at 1.6 MPa and 280–400°C. Their activity was similar to the activity of industrial and laboratory MoO3/Al2O3 samples prepared by conventional impregnation with solution of ammonium heptamolybdate. The advantage of the SIM method is that calcination, producing nitrogeneous waste gases, is not required and that all deposited molybdenum species are adsorbed and not precipitated. 相似文献
95.
Lin Ye Klaus Friedrich Joachim Kstel Yiu-Wing Mai 《Composites Science and Technology》1995,54(4):349-358
Relationships between impregnation mechanisms, consolidation quality and resulting mechanical properties of CF/PEEK thermoplastic composites manufactured from a commingled yarn system have been investigated. A small compression mould was used to apply the different processing conditions (i.e. pressure, holding time and processing temperature). The consolidation quality of finished samples was characterized mainly through microscopic studies of the microstructure of the material associated with density measurements and evaluations of mechanical properties using a small transverse flexure testing facility. A model for qualitatively describing the impregnation and consolidation processes in commingled-yarn-based thermoplastic composites was developed, which predicts variations of void content during consolidation as well as the time, temperature and pressure required to reach full consolidation. Good correlations between predictions and the experimental data indicate the success of the approach. For a desired, minimum level of void content (Xv = 0.5%), optimum processing windows for manufacturing of CF/PEEK composite parts from the commingled yarn preform are suggested. 相似文献
96.
Alexei V. Shevchenko Elena V. Dudnik Alexei K. Ruban Vladimir M. Vereshchaka Viktor P. Red’ko Lidiya M. Lopato 《Powder Metallurgy and Metal Ceramics》2005,44(3-4):105-111
The properties of ZrO2 - 3 mole% Y2O3 nanocrystalline powder prepared by diffusion impregnation are studied. The original nanocrystalline powder of M-ZrO2 is prepared with hydrothermal treatment of aqueous zirconium hydroxychloride solution by different regimes. It is found that after diffusion impregnation for all of the powders with yttrium oxide two solid solutions are formed (F-ZrO2 and M-ZrO2) in mixture. It is established that the morphological features typical for the original powders are retained. The efficiency of diffusion impregnation is determined by the slightly-agglomerated powder with a high degree of crystallinity.__________Translated from Poroshkovaya Metallurgiya, Nos. 3–4(442), pp. 3–11, March–April, 2005. 相似文献
97.
王清玉 《水电自动化与大坝监测》1999,(1)
某大坝零星分布有浸水现象,利用高频电磁波在不同介质传播特征的差异,借助地质雷达勘察坝体“散浸”,从而揭示了坝体介质的富水特征及其不均匀特性,为地质论证“散浸”范围进而推断其原因提供了部分依据。 相似文献
98.
本文首次报导了湖北省微细浸染型金矿金的赋存状态。通过研究确定了金属于超显微粒级的不可见金,查明了金的赋存形式多样:毒砂中的金是以类质同象晶格金的形式存在,Au~(1+)替代毒砂中的Fe~(2+);粘土矿物中的金呈小园球状的次显微金和胶体金粒被吸附在水云母、高岭石晶体边缘,自然金粒度为0.02~0.35微米。此成果为研究本矿床成因,矿床综合评价和工业利用提供了可信依据。 相似文献
99.
以四硫代钼酸铵溶液和硝酸镍溶液为浸渍液,根据活性组分Ni和Mo浸渍顺序的不同,采用真空饱和浸渍法制备了MN系列和NM系列 NiMoS/γ-Al2O3催化剂。在固定床加氢中试反应装置上研究了NiMoS/γ-Al2O3催化剂对二苯并噻吩加氢反应的催化性能,结果表明,NiMoS/γ-Al2O3催化剂对二苯并噻吩加氢反应具有良好的活性和选择性。Ni助剂的加入,有利于二苯并噻吩加氢反应的活性和选择性。MN-0.3为最优NiMoS/γ-Al2O3催化剂。在空速10 h-1、反应压力2.0 MPa、氢油体积比300∶1、氢气预处理温度320 ℃和反应温度300 ℃条件下,催化剂对二苯并噻吩加氢反应转化率达83.9%,加氢反应活性较高。 相似文献
100.
Jinshuo Qiao Kening Sun Naiqing Zhang Bing Sun Jiangrong Kong Derui Zhou 《Journal of power sources》2007
In this paper, Ni/YSZ and Ni–CeO2/YSZ anodes for a solid oxide fuel cell (SOFC) were prepared by tape casting and vacuum impregnation. By this method, the Ni content in the anode could be reduced compared to the traditional tape casting method. It was found that adding CeO2 into the Ni/YSZ anode by a Ni(NO3)2 and Ce(NO3)3 mixed impregnation could further enhance cell performance. This was investigated in H2 at 1073 K. XRD patterns indicated that CeO2 and Ni were separate phases, and the CeO2 addition could enhance the Ni dispersion on the YSZ framework surface which was observed by SEM images. It was shown that adding CeO2 into the Ni anodes could decrease the cell polarization resistance. The maximum power density for cells with 25 wt.% Ni, 5 wt.% CeO2–25 wt.% Ni/YSZ, or 10 wt.% CeO2–25 wt.% Ni/YSZ anode was 230 mW cm−2, 420 mW cm−2 and 530 mW cm−2, respectively, in H2 at 1073 K. The OCV for these cells was 1.05–1.09 V, indicating that a dense electrolyte film was obtained by co-firing porous YSZ layer and dense YSZ layer. 相似文献