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Development of Preparation Systems with K_2CsSb Photocathodes and Study on the Preparation Process

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Chinese Physics Letters 2019年第2期36卷 8-11页

作者： Fan Zhang xiao-ping li xiao-Shen li Institute of High Energy Physics Chinese Academy of Sciences Key Laboratory of Particle Acceleration Physics and Technology Institute of High Energy PhysicsChinese Academy of Sciences

The next generation of advanced light sources requires photons with large average flux and high brightness,which needs advanced electron gun matched with excellent photocathode materials. K_2CsSb photocathode has the advantages of high quantum efficiency, long lifetime and instantaneous response. This study introduces the design of a set of K_2CsSb photocathode preparation systems and detailed preparation process of K_2CsSb photocathodes, including sequential deposition process and co-deposition process, and finally develops a K_2CsSb photocathode. The influence of laser power on the quantum efficiency is also investigated.

关键词： Cs Sb St Development of Preparation Systems with K2CsSb Photocathodes and Study on the Preparation Process

Improved QO-STBC for three and four transmit antennas

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The Journal of China Universities of Posts and Telecommunications 2010年第4期17卷 42-46页

作者： JIA Ming-ru xiao li-ping College of Information Science and Engineering Yanshan Universitys Qinhuangdao 066004 China

A new quasi-orthogonal space-time block code （QO-STBC） based on ABBA code with lower decoding complexity and higher bit error statistics （BER） performance was proposed by U. Park recently, which can obtain full transmission rate and full diversity. In this article, the authors proposed an improved U. Park scheme based on rotational ABBA code. For eliminating the interference terms resulting from neighboring signals during signal detection, two different matrixes are used. And independent decoding can be realized when maximum-likelihood decoding at the receiver is used. Simulation results demonstrate that the BER performance is improved dramatically without increasing the decoding complexity compared with U. Park scheme.

关键词： independent decoding multiple antennas QO-STBC

Microscopic characterization of semi-solid aluminium alloys

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International Journal of Minerals,Metallurgy and Materials 2010年第3期17卷 290-296页

作者： Ya-lin Lu Miao-quan li Xing-cheng li xiao-ping li School of Materials Science and Engineering Northwestern Polytechnical University Xi＇an 710072 China School of Materials Engineering Jiangsu Teachers University of Technology Changzhou 213000 China

The microstructural evolution and element distribution of the Al-4Cu-Mg alloy during semi-solid compression were investigated, and the precipitate behavior and dislocation morphology were discussed. The experimental results show that the microstructure, the number of CuAl2 （θ phase） precipitates, and the dislocation density of the Al-4Cu-Mg alloy depend apparently on the process parameters. More segregation of Cu at the grain boundary happens with an increase of deformatinn temperature and a decrease of strain rate, leading to an increase in the number of θ phase. With an increase of height reduction, Cu segregation at the grain boundary decreases gradually. Moreover, unique dislocation morphologies including helical dislocations and dislocation loops appear at different process parameters and evolve to reduce the stored energy.

关键词： aluminum alloys semi-solid state microstructural evolution dislocation

A New Route for Synthesis of Entecavir

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Chinese Chemical Letters 2006年第7期17卷 907-910页

作者： li Wei GUO Yuan Jing xiao li ping YANG Department of chemistry East China Normal University Shanghai 200062

A new economical synthetic route of the key intermediate 6. The synthesis of a modified Mitsunobu reaction. of entecavir was presented, involving the preparation 6 was conveniendy achieved in good overall yield by a m... 详细信息

关键词： Entecavir new route synthesis.

1,25-dihydroxyvitamin D_3 regulates LPS-induced cytokine production and reduces mortality in rats

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World Journal of Gastroenterology 2008年第24期14卷 3897-3902页

作者： xiao-ping Qi Pei li Gang li Zhen Sun Jie-Shou li School of Medicine Nanjing University Department of GeneralSurgery Jinling Hospital 305 Zhongshandong Road Nanjing210002 Jiangsu Province China

AIM： To study the immunoregulatory effect of 1,25-dihydroxyvitamin-D3 Von dominant Thl response in rats. METHODS： Sixty adult Lewis rats were randomized into three groups. Rats in group 1 （n=25） were treated with 1,25-（OH）2D3 first and then challenged with LPS, rats in group 2 （n=25） were treated with vehicle first and then challenged with LPS. Ten animals in groups 1 and 2 were preserved for mortality observation. The remaining animals were injected （i.p） with endotoxin, 24 h after the last administration of 1,25-（OH）2D3 and vehicle. Rats in group 3 （n=10） were treated with 1,25-（OH）2D3 only. Serum IL-12, IFN-y, IL-2 and IL-4 levels were measured and target gene of 1,25-（OH）2D3 on Th cells was studied after 6 h. Gene abundance was verified by real-time quantitative PCR. RESULTS： No death occurred in rats pretreated with 1,25-（OH）2D3 after LPS injection. Death occurred 9 h after LPS injection in rats pretreated with the vehicle, and the number of deaths was 5 within 24 h, with a mortality rate of 50%. There was no change in the number of deaths within 96 h. Six hours after endotoxin stimulation, serum IL-12 and IFN-y levels decreased significantly in rats pretreated with 1,25-（OH）2D3 as compared with those in rats pretreated with the vehicle. The serum content of these two cytokines was very low in rats not challenged by endotoxin, and there was a significant difference as compared with the previous two groups. CONCLUSION： 1,25-（OH）2D3 attenuates injuryinduced by the lethal dose of 1PS, regulates Thl and Th2 cells at the transcription level, and dominantly responds to cytokine production in rats.

关键词： Endotoxin Cytokine 1,25-dihydroxy-vitamin-D3 Immunoregulation Mortality

Microstructure and mechanical properties of as-extruded Mg-Sn-Zn-Ca alloy with different extrusion ratios

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Transactions of Nonferrous Metals Society of China 2018年第11期28卷 2191-2199页

作者： Yang ZHANG xiao-yang CHEN Ya-lin LU xiao-ping li School of Materials Engineering Jiangsu University of TechnologyChangzhou 213001China School of Mechanical Engineering Jiangsu University of TechnologyChangzhou 213001China

The effect of extrusion ratio on microstructure and mechanical properties of as-extruded Mg-6Sn-2Zn-1Ca （TZX621）（mass fraction, %） alloy was investigated. It is found that incomplete dynamic recrystallization （DRX） took place in as-extrudedTZX621 alloy. As the extrusion ratio was increased from 6 to 16, both fraction of un-DRXed grains and average size of DRXedgrains in as-extruded TZX621 alloy decreased and the basal texture was weakened. Coarse CaMgSn phase was broken into particlesand fine Mg2Sn phase precipitated from α-Mg matrix during hot extrusion. Yield strength, ultimate tensile strength and elongation ofas-extruded TZX621 alloy with extrusion ratio of 16 reached 226.9 MPa, 295.6 MPa and 18.1%, which were improved by 36.0%,17.7% and 13.5%, respectively, compared to those of as-extruded TZX621 alloy with extrusion ratio of 6.

关键词： Mg-Sn alloy extrusion ratio microstructure texture mechanical properties

Microstructure and mechanical properties of AZ91-Ca magnesium alloy cast by different processes

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China Foundry 2018年第4期15卷 263-269页

作者： xiao-yang chen yang zhang ya-lin lu xiao-ping li Key lab of advanced Materials Design and Additive Manufacturing of Jiangsu Province Jiangsu University of TechnologyChangzhou 213001China

The microstructure and mechanical properties of magnesium （Mg） alloys are significantly influenced by the casting process. In this paper, a comparative study on microstructure and mechanical properties at ambient and elevated temperatures of AZ91-2wt.% Ca （AZX912） Mg alloy samples prepared by gravity casting （GC）, squeeze casting （SC） and rheo-squeeze casting （RSC）, respectively, was carried out. The results show that mMg grains in SC and RSC samples are significantly refined compared to the GC sample. The average secondary dendritic arm spacing of AZX912 alloy samples decreases in the order of GC, SC and RSC. As testing temperature increases from 25 ~C to 200 ~C, strength of AZX912 alloy samples is reduced, while their elongation is increased continuously. Compared to GC and SC processes, RSC process can improve the mechanical properties of AZX912 alloy at both ambient and elevated temperatures. The enhancement of mechanical properties of RSC sample over GC and SC samples mainly results from grain refinement in the as-cast microstructure of AZX912 alloy.

关键词： magnesium alloys casting process microstructure mechanical properties

Point defect concentrations of L12-Al3X(Sc, Zr, Er)

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Rare Metals 2018年第8期37卷 699-706页

作者： Shun-ping Sun xiao-ping li Jie Yang Hong-Jin Wang Yong Jiang Dan-Qing Yi School of Materials Engineering Jiangsu University of Technology Changzhou 213001 China School of Materials Science and Engineering Central South University Changsha 410083 China

The point defect concentrations of L12-A13X（Sc, Zr, Er） were systematically investigated using the first- principle calculations with thermodynamics approach. The results show that the constitutional point defects of off- stoichiometric L12-A13X（Sc, Zr, Er） prefer to occur in X sublattice, that is X anti-site in X-rich alloy and X vacancy in Al-rich alloy, respectively. And A1 anti-site also has a high density in Al-rich Llz-A13X（Sc, Er）. It is found that the point defect concentrations of stoichiometric L12-A/3X（Sc, Zr） follow in the sequence as： A1 vacancies （VA0 〉 X vacancies （Vx）〉 X anti-sites （XA1）〉 A1 anti- sites （Alx）. The point defect concentration of stoichio- metric A13Er is similar to that of L12-A13X（Sc, Zr）. The result suggests that the A1 vacancy （VA1） is a dominant point defect in L12-A13X（Sc, Zr, Er）. A simple parameter Hvx-HVA1 can be used for a rough estimation of the point defect concentrations in L12-A13X structure. Some rules of point defect concentrations for L12-A13X（Sc, Zr, Er） are also revealed.

关键词： L12-A13X(Sc Zr Er) Point defect First-principle calculation

Dual-porosity model of rate transient analysis for horizontal well in tight gas reservoirs with consideration of threshold pressure gradient

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Journal of Hydrodynamics 2018年第5期30卷 872-881页

作者： li-na Cao xiao-ping li Ji-qiang Zhang Cheng Luo xiao-hua Tan China ZhenHua Oil Co. Ltd. Beijing 100031 China State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum University Chengdu 610500 China CNOOC Zhanjiang Co. Ltd. Zhanjiang 524057 China Geological Exploration and Development Research Institute of CNPC Chuanqing Drilling Engineering Ltd. Chengdu 610056 China

Most researches of the threshold pressure gradient in tight gas reservoirs are experimental and mainly focus on the transient pressure response, without paying much attention to the transient rate decline. This paper establishes a dual-porosity rate transient decline model for the horizontal well with consideration of the threshold pressure gradient, which represents the non-Darcy flow in a fracture system. The solution is obtained by employing the Laplace transform and the orthogonal transform. The bi-logarithmic type curves of the dimensionless production rate and derivative are plotted by the Stehfest numerical inversion method. Seven different flow regimes are identified and the effects of the influence factors such as the threshold pressure gradient, the elastic storativity ratio, and the cross flow coefficient are discussed. The presented research could interpret the production behavior more accurately and effectively for tight gas reservoirs.

关键词： Rate transient analysis horizontal well dual-porosity threshold pressure gradient tight gas reservoirs