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Role of gallium wetting layer in high-quality ZnO growth on sapphire (0001) substrates

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Science china(Physics,Mechanics & Astronomy) 2004年第5期47卷 612-620页

作者： ZENG Zhaoquan1,3, WANG Yong2, du Xiaolong1, MEI Zengxia1, KONG Xianghe3, JIA Jinfeng1, xuE Qikun1 & ZhanG Ze2, 4 1. State Key Laboratory for Surface Physics, Institute of Physics, Chinese Academy of sciences, beijing 100080, china 2. Laboratory of Electron Microscopy, Institute of Physics, Chinese Academy of sciences, beijing 100080, china 3. college of Physics and Engineering, Qufu Normal university, Qufu 273165, china 4. beijing university of technology, beijing 100022, china State Key Laboratory for Surface Physics Institute of Physics Chinese Academy of Sciences Beijing China college of Physics and Engineering Qufu Normal University Qufu China Laboratory of Electron Microscopy Institute of Physics Chinese Academy of Sciences Beijing China beijing university of technology Beijing China

A Ga wetting layer was used to modify the surface structure of sapphire (0001) substrate to prepare high-quality ZnO film by radio frequency plasma-assisted molecule beam epitaxy. We found that this Ga layer plays a crucial role in eliminating 30 rotation domains, controlling polarity and decreasing defect density in ZnO epilayers, as demonstrated by in situ reflection high energy electron diffraction, ex situ high resolution X-ray diffraction and high resolution cross-sectional transmission electron microscopy. Zn-polar film of ZnO was determined by convergent beam electron diffraction. A Ga bilayer model is proposed to understand the effects of the Ga wetting layer on high-quality ZnO growth.

关键词： Ga wetting layer, sapphire, polarity, defect density, zinc oxide, rf-MBE, RHEED, HRXRD, TEM, CBED.

Analysis of china’s Water Security and Virtual Water Trade

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Chinese Journal of Population,Resources and Environment 2006年第4期4卷 18-23页

作者： Wang Hongrui1,2,Liu Xinghan3,Dong Yanyan1,2,Wang Junhong1,2 1.college of Water sciences,beijing Normal university,beijing 100875,china 2.Key Laboratory for Water and Sediment sciences Ministry of Education,beijing 100875,china 3.college of Economics&Management,beijing university of technology,beijing 100022,china college of Water sciences Beijing Normal University Key Laboratory for Water and Sediment sciences Ministry of Education

Producing goods and services all needs water *** water used in the process of an agricultural or industrial product is called the"Virtual Water"contained in this product. Through international trade,water-scarce countries and regions could purchase water-intensive products--especially foods,from water-rich countries to balance their water deficits and achieve water *** is one of the 13 most water-deficit countries whose water safety have been severely *** paper generalized the recent global research development and made a brief introduction about the methods calculating virtual water content in specific *** a case study,we qualified china's annual virtual water flows from year 2000 to 2002 with trade in crops,and ended with some policy advice for application and practice of virtual water strategy.

关键词： water security virtual water virtual water trade crops

Synchronization of Digital Chaos in Secure Communication Systems

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Journal of university of Science and technology beijing 2001年第4期8卷 299-305页

作者： Geng Zhao, Deling Zheng, ShaojunHuang 1)college of Electric Science and technology beijing. beijing 100070, china 2)Information Engineering School, university of Science and technology beijing. beijing 100083, china college of Electric Science and technology beijing Beijing 100070 China Information Engineering School University of Science and Technology Beijing Beijing 100083 China

The theories of synchronization based on secure communications using digital chaos are presented. A new synchronous method-cycles-interval Pulse drive is developed and realized. Experimental results show it is available, and in order to reduce synchronous noise, a method using model references solves the ratio of signal power to noise power, so the secure communication system can be realized.

关键词： digital chaotic synchronization cycles-interval pulses drive synchronous noise model reference

A new scheme of climate-vegetation regionalization in the Hengduan Mountains Region

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Science china Earth sciences 2024年第3期67卷 751-768页

作者： xueqin ZhanG Xiaoming xu Xiang LI Peng CUI du ZHENG Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China university of Chinese Academy of sciences Beijing 100049China china-Pakistan Joint Research Center on Earth sciences Chinese Academy of Sciences-Higher Education Commission of PakistanIslamabad 45320Pakistan

The Hengduan Mountains Region(HMR) is essential for the future ecological protection, clean energy production,Sichuan-Xizang and Yunnan-Xizang railways, and other major infrastructure projects in china. The distributions of climate and vegetation exhibit significant regional differentiation and vertical zonality due to the rugged longitudinal ranges and gorges and the complex disaster-prone environments in HMR. Therefore, it is urgent to develop the climate-vegetation regionalization in HMR to effectively satisfy the national requirements such as agricultural production and ecological protection, mountain disaster risk prevention, and major project construction. We here develop a new scheme of climate-vegetation regionalization with the latest demarcation outcome of HMR, the ground observation from 122 meteorological stations in HMR and its surrounding areas during 1990–2019, and the high-precision remote sensing data of land cover types. The new scheme first constructs the regionalization index system, fully considering the extraordinarily complicated geomorphic pattern of mountains and valleys, the scarcity of meteorological observations, and the remarkable differentiation of climate and vegetation in HMR. The system consists of three primary regionalization indices(i.e., days with daily average temperature steady above 10°C, aridity index, and main vegetation types, dividing the temperature zones, moisture regions, and vegetation subregions, respectively) and three auxiliary indices of the accumulated temperature above 10°C, and the temperatures in January and July. Then, the HMR is divided into five temperature zones, 20 moisture regions, and 55 vegetation subregions. Compared with previous regionalization schemes, the new scheme optimizes the climate spatial interpolation model of thin plate smoothing spline suitable for the unique terrain in HMR. Moreover, the disputed division index threshold between different climatic zones(regions) is scientifically clarifi

关键词： Climate-vegetation regionalization Thin plate smoothing spline(TPSS) GeoDetector Stepwise downscaling pane division method Hengduan Mountains Region

Analysis of moment invariants under general linear transformation

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Science china(Information sciences) 2010年第7期53卷 1305-1311页

作者： DIAO LuHong1, LI Hua2, ZhanG Sen1 & LIU Lei1 1college of applied sciences, beijing university of technology, beijing 100124, china 2National Center of Intelligent Computing, Institute of Computing technology, Chinese Academy of Science, beijing 100080, china college of applied sciences Beijing University of Technology National Center of Intelligent Computing Institute of Computing Technology Chinese Academy of Science

This paper presents the necessary and sufficient condition of moment invariants under general linear transformation. Based on this condition, arbitrary order and dimensional moment invariant sets can be constructed. D... 详细信息

关键词： moment invariants independence linear transformation

GM-CSF-induced Ca_(2+) -activated non-voltage-dependent inwardly rectifying K_+ channel in murine peritoneal exudate macrophages

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Chinese Science Bulletin 1997年第11期42卷 947-952页

作者： ZhanG Xiaofeng, FENG Meifu, WU Caihong and ZHOU Pei’aiState Key Laboratory of Biomembrane and Membrane Biotechnology, Chinese Academy of sciences, beijing 100080, china 1 . In-stitute of Zoology, Chinese Academy of sciences, beijing 100080, china 2 college of Life sciences, Peking university, beijing 100871, china State Key Laboratory of Biomembrane and Membrane Biotechnology Chinese Academy of Sciences Beijing 100080 China

GRANULOCYTE-MACROPHAGE colony-stimulating factor(GM-CSF),a member in the family ofglycoprotein cytokines,can not only act to stimulate proliferation of immature progenitors,butalso enhance differentiated functions of mature effector *** has two kinds of biologicaleffects on mature effector cells,*** effect and indirect *** latter is also

关键词： K+ channel patch clamp GM-CSF macrophage.

Phase relationship of complex multi-component system in chromate cleaner production

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Progress in Natural Science:Materials International 2007年第7期17卷 845-850页

作者： Ge Xinlei~1 Wang Xidong~(1,3**) Zheng Shili~2 Zhang Mei~1 Zhang Yi~2 (1.Department of Physical Chemistry,university of Science and technology beijing,beijing 100083,china 2.Institute of Process Engineering,Chinese Academy of sciences,beijing 100080,china 3.college of Engineering,Peking university,beijing 100871,china) Department of Physical Chemistry University of Science and Technology Beijing Beijing 100083 China college of Engineering Peking University Beijing 100871 China Institute of Process Engineering Chinese Academy of Sciences Beijing 100080 China

The phase relationships of the complex multi-component systems in the liquid-phase oxidization and separation process related with the chromate cleaner production are investigated theoretically and *** phase diagram of main system Fe- Cr2O4-KOH-O2of oxidization process and the relationship of its standard Gibbs free energy change with temperature are calculated.A se- ries of phase diagrams of the separation process at different temperatures,such as K（Na）OH-K（Na）2CrO4-H2O,KOH-KAlO2-H2O, K（Na）OH-K（Na）2CO3-H2O,K（Na）OH-K（Na）HCO3-H2O and K（Na）HCO3-K（Na）2CrO4-H2O have also been *** ex- periments are carried out to verify the calculated *** results showed that the sub-molten salt media are suitable for the oxidization and separation processes;FeCr2O4can be oxidized across a wide range of temperature;K（Na）2CrO4can be separated from K（Na）AlO2system at appropriate temperature and proper concentration;the crystallization of carbonate is easier than that of K（Na）2CrO4.

关键词： chromite chromate system thermodynamics calculation phase diagram

Structural Analysis and Identification of Cis-Elements of Rice osRACD Gene

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Acta Biochimica et Biophysica Sinica 2004年第3期36卷 191-198页

作者： Yun-Zhe xu, Rui-Lin YOU and Nai-Hu WU Institute of Genetics and Developmental Biology, Chinese Academy of sciences, beijing 100080, china 2college of Life sciences, Peking university, beijing 100871, china Institute of Genetics and Developmental Biology Chinese Academy of Sciences college of Life sciences Peking University

The osRACD gene correlated with fertility transformation in the photoperiod sensitive genic male sterile rice (PGMR), Nongken 58S, encoded a rice (Oryza sativa L. ssp. japonica) small GTPase belonging to the Rac/Rho family. Inverse PCR was performed to amplify a fragment about 1.4 kb in 5' upstream region of the osRACD promoter. Deletion mutation and gel mobility shift assay characterized two fragments (–799 to –686 nt, and –686 to –431 nt) in the osRACD promoter that could be involved in its transcriptional regulation. When these two deletion fragments were used as probe respectively, a retarded band appeared in the nuclear extracts of fertile 58S rice under short day (58S-SD). Whereas no retarded band was shown in the nuclear extracts of sterile 58S rice under long day (58S-LD). Competition assay indicated that the factors in the retarded bands binding to these two fragments were the same trans-acting factor (termed rice factor, RF). The binding affinity of RF was affected by phosphorylation and was higher in SD-growth rice than that of LD-growth rice.

关键词： photoperiod-sensitive male genic sterile rice osRACD gene photoperiod fertility transformation cis-element

Parameter identification theory of a complex model based on global optimization method

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Science china(Physics,Mechanics & Astronomy) 2008年第11期51卷 1722-1732页

作者： QU Jie1, JIN QuanLin2 & xu BingYe3.1.college of Automotive Engineering, South china university of technology, Guangzhou 510640, china 2 beijing Research Institute of Mechanical and Electrical technology, beijing 100083, china 3 Department of Engineering Mechanics, Tsinghua university, beijing 100084, china college of Automotive Engineering South China University of Technology Guangzhou China beijing Research Institute of Mechanical and Electrical technology Beijing China Department of Engineering Mechanics Tsinghua University Beijing China

With the development of computer technology and numerical simulation technology, computer aided engineering (CAE) technology has been widely applied to many fields. One of the main obstacles, which hinder the further application of CAE technology, is how to successfully identify the parameters of the selected model. An elementary framework for parameter identification of a complex model is provided in this paper. The framework includes the construction of objective function, the design of the optimization method and the evaluation of the identified results, etc. The parameter identification process is described in this framework, taking the parameter identification of the superplastic constitutive model considering grain growth for Ti-6Al-4V at 927°C as an example. The objective function is the weighted quadratic sums of the difference between the experimental and computational data for the stress-strain relationship and the grain growth relationship; the designed optimization method is a hybrid global optimization method, which is based on the feature of the objective function and incorporates the strengths of genetic algorithm (GA), the Levenberg-Marquardt algorithm and the augmented Gauss-Newton algorithm. The reliability evaluation of parameter identification result is made through the comparison between the calculated and experimental results and between the theoretical values of the parameters and the identified ones.

关键词： constitutive model parameter identification theory inverse analysis global optimization