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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 {1. for Surface Physics, institute of Physics, chinese academy of sciences, beijing 1.0080, China 2. {1. of Electron Microscopy, institute of Physics, chinese academy of sciences, beijing 1.0080, China 3. College of Physics and Engineering, Qufu Normal University, Qufu 2731.5, China 4. beijing University of Technology, beijing 1.0022, China 1. State key {1. for Surface Physics Institute of Physics Chinese Academy of Sciences 100080 Beijing China 2. College of Physics and Engineering Qufu Normal University 273165 Qufu China 3. laboratory of Electron Microscopy Institute of Physics Chinese Academy of Sciences 100080 Beijing China 4. beijing University of Technology 100022 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.

SHRIMP zircon U-Pb age and Nd isotopic study on the Nyainqêntanglha Group in Tibet

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Science China Earth sciences 2005年第9期48卷 1377-1386页

作者： HU Daogong1. WU Zhenhan1. JIANG Wan1. SHI Yuruo2, YE Peisheng1.& LIU Qisheng1.1. institute of Geomechanics, {1. academy of Geological sciences, beijing 1.0081. China 2. institute of {14., {1. academy of Geological sciences, beijing SHRIMP Centre, beijing 1.0037, China 1. institute of Geomechanics Chinese Academy of Geological Sciences 100081 Beijing China 2. institute of {1. Chinese Academy of Geological Sciences Beijing SHRIMP Centre 100037 Beijing China

The Nyainqêntanglha Group is traditionally viewed as the oldest metamorphic basement in the Lhasa block, but its formation age and tectonic setting remain debate. Zircons extracted from the metamorphic sequence of volcanics and intrusions of the Nyainqêntanglha Group, 1. km west of Nam Co in northern Lhasa block, have been investigated by cathodolu- minescence (CL), backscattered (BSE) and dated by ion microprobe (SHRIMP). We conclude that the U-Pb age of 787±9 Ma of zircons from the trondhjemite imposes a constraint on maxi- mum protolith age, and minimum formation age of the Nyainqêntanglha Group is constrained by U-Pb age of 74.±8 Ma of zircons from the granite. The formation age of the Nyainqêntanglha Group is consistent with sedimentary age of Greater Himalayan rocks, showing that they devel- oped coevally in an arc-basin tectonic setting of Neoproterozoic active continental margin along the northern margin of the India shield. The inherited zircons from the tholetiite and granite give older 207Pb/206Pb ages from 94. to 1.66 Ma. The positive εNd( t ) value indicates that the mafic rocks were derived from the depleted mantle, but contaminated by the older continental crustal material. Integrated Nd model age and U-Pb age data provide excellent evidence for the exis- tence of Mesoproterozoic basement in the Lhasa block during Neoproterozoic time.

关键词： Nyainqêntanglha Group, SHRIMP dating, Nd isotope, Neoproterozoic, Tibet.

Carbon Storage and Vertical Distribution in Three Shrubland Communities in Gurbantünggüt Desert,Uygur AutonomousRegion of Xinjiang,Northwest China

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chinese Geographical Science 2012年第5期22卷 541-549页

作者： GONG Yanming 1 ,HU Yukun 1 ,FANG Fei 1 ,LIU Yanyan 1 ,LI Kaihui 1 ,ZHANG Guangming 2 (1.key laboratory of Biogeography and Bioresource in Arid Land,Xinjiang institute of Ecology and Geography,chinese {4. of sciences,Urumqi 830011,China 2.State key laboratory of Vegetation and Environmental Change, institute of Botany,chinese {4. of sciences,beijing 100093,China) 1. key {1. of Biogeography and Bioresource in Arid Land Xinjiang Institute of Ecology and Geography Chinese Academy of Sciences Urumqi 830011 China 2. State key {1. of Vegetation and Environmental Change Institute of Botany Chinese Academy of Sciences Beijing 100093 China

This study was carried out in the Gurbantünggüt Desert,Uygur Autonomous Region of Xinjiang,Northwest China in August,*** quantify the storage,contribution and vertical distribution patterns of plant biomass carbon (PBC)and soil organic carbon(SOC)in the study area,we investigated the carbon concentrations and its vertical distribution in three different desert shrubland communities dominated by Reaumuria soongorica,Haloxylon ammodendron+*** and Tamarix ramosissima+***,*** analyzed vertical distribution of root biomass carbon and soil carbon contents by excavating soil profiles for each dominated *** results show that SOC is considerably the larger carbon pool in the soil layers of 1.0-3.0 m(the mean value of three shrubland communities is 38.4.%)and 3.0-5.0 m(the mean value is 4..24.).In contrast,70.74.of belowground biomass carbon storage in 0-1.0 m layer,and its content decrease with increasing soil *** Haloxylon ammodendron+R. soongorica shrubland community has the highest belowground biomass carbon among three selected communities. This study highlights the importance of SOC stored in deep soil layers(lower than 3.0 m from the surface)in arid shrubland communities in the global carbon *** addition,it provides the data support for revealing deep soil solid carbon potential,and offers scientific basis for the further research in the carbon cycle of terrestrial ecosystem.

关键词： shrubland community plant biomass carbon soil organic carbon vertical distribution Gurbantünggüt desert

Cesium accumulation by bacterium Thermus sp. TibetanG7:hints for biomineralization of cesium-bearing geyserite in hot springs in Tibet,China

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chinese Science Bulletin 2007年第19期52卷 2680-2686页

作者： WANG HaiLei1,2,3, ZHENG MianPing1,2,3 & HUANG XiaoXing4.1 institute of mineral resources, chinese {4. of Geological sciences (CAGS), beijing 100037, China 2 R&D Center for Saline Lake and Epithermal Deposits, CAGS, beijing 100037, China 3 Open laboratory of Saline Lake Resourses and Environment, CAGS, beijing 100037, China 4.laboratory of Microbial resources, institute of Microbiology, chinese academy of sciences, beijing 100081, China institute of {1. resources Chinese Academy of Geological Sciences (GAGS) Beijing 100037 China

The bacterium Thermus sp. TibetanG7, isolated from hot springs in Tibet, China, was examined for the ability to accumulate cesium from solutions. Environmental conditions were simulated and the effects of pH, K+, Na+ and K+-regimes were then studied to determine the possible role of the bacterium in the formation of cesium-bearing geyserite around these hot springs. In despite of the inhibition of K+ and Na+, the bacterium Thermus sp. TibetanG7 revealed noticeable accumulation of cesium from solutions, with maximum accumulations of 53.4. and 4..4.0}μmol Cesium/g cell dry weight in Na+ and K+ inhibition experiments, respectively. The accumulation of cesium by this microorganism is rapid, with 4.%―50% accumulated within the first 5 min. K+-deficient cells showed a much higher capacity of cesium accu- mulation compared with K+-sufficient cells. It is evident that the bacteria within the genus thermus play a significant role in the cesium assembly. The formation of cesium-bearing geyserite is also considered.

关键词：铯元素沉积物硅华生物矿化

Principles and methods of quantitative analysis on b-axis disorder in 2 : 1.dioctahedral phyllosilicate

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chinese Science Bulletin 1997年第22期42卷 1908-1912页

作者： WANG Ling and ZHANG Zhenyu1. Changsha institute of Geotectonics,{1., Changsha 4.0}01., China 2. institute of geology,{1., beijing 1.0029, China Changsha institute of Geotectonics Chinese Academy of Sciences Changsha China institute of {1. Chinese Academy of Sciences Beijing China

IN XRD patterns of clay minerals, a phenomenon that strong peaks often have (00l) and(hkl) (k=3n) indices and show symmetric figures can be seen commonly, while a minorityof reflection peaks (hkl) (k≠3n) are comparat... 详细信息

关键词： b-axis disorder pyrophvllile 2 phyllosilicate clay minerals dioctahedral minerals orientating structure of hy-droxyls crystal structure analysis DTA-TG.

Effects of diatoms on reproduction and growth of marine copepods

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Progress in Natural Science:Materials International 2004年第10期14卷 1-7页

作者： ZHANG Guangtao 1,2 and SUN Song 1 (1.key laboratory of Marine Ecology&Environment sciences,institute of Oceanology,{4. academy of sciences,Qingdao266071,China 2.Graduate School,{4. academy of sciences,beijing100039,China) chinese Acad Sci Inst Oceanol Key Lab Marine Ecol & Environm Sci Qingdao 266071 Peoples R China chinese Acad Sci Grad Sch Beijing 100039 Peoples R China

Two hot spots in marine ecology,deleterious effects of diatoms and feeding selectivity of copepods,as well as new progress on these two issues achieved in the recent ten years,are *** two issues are considered correlated *** and their metabolites can induce deleterious effects on growth,reproduction and development of copepods,including increase of mortality and decrease of egg production,hatching and growth *** negative effects,resulting from either chemical toxin or nutritional defi-ciency,can be conquered in natural environments by diverse *** is therefore concluded that deleterious effects of diatoms observed in laboratory or during blooming period are only a special case that accommodation of feeding strategy of copepods is *** under-stand their feeding strategy in natural environments is a prerequisite to explaining the mechanisms of deleterious effects caused by diatoms,and makes it possible to re-evaluate the energy flow in marine ecosystems.

关键词： diatoms copepod feeding strategy reproduction deleterious effects

Input function and simulated distributions of tritium in the North Pacific

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Science China Earth sciences 2010年第3期53卷 441-453页

作者： BA Qi1.2 & XU YongFu1.1.State key {1. of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, institute of Atmospheric Physics, chinese academy of sciences, beijing 1.0029, China 2 Graduate University of chinese academy of sciences, beijing 1.004., China 1. State key {1. of Atmospheric Boundary Layer Physics and Atmospheric Chemistry Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China2. Graduate University of Chinese Academy of Sciences Beijing 100049 China

An ocean general circulation model (OGCM) of the North Pacific with a southern open boundary condition is used to simulate the distribution and transport of tritium in the North Pacific. First, the observed tritium in precipitation dataset of GNIP/ISOHIS is chosen, and used to develop an input function of tritium for the model domain from 1.51.to 1.97 in terms of the triangulation for interpolation. Then, the input function is used as an upper flux for the tritium model. The OGCM with tritium is integrated for 4. years with the initial condition of zero tritium concentrations. Compared with the observations from GEOSECS and WOCE, the model generates a meridional gradient of surface tritium concentrations and the high tritium concentrations in the subsurface layer, which is consistent with that indicated in the observations. The simulated time series of total tritium fluxes from the atmosphere to the ocean shows a spike in 1.63. The total inventory of tritium in the ocean changes slowly with time after 1.75. Tritium enters the higher-latitude region, and then is mainly transported by the subsurface process towards the equatorial region, which is well simulated in the model. However, the difference mainly occurs at 30°N–4.°N, which can be seen also in the simulation of CFCs. This difference may partly originate from the insufficient description of physical processes in the OGCM. Nevertheless, some uncertainties exist in the development of the tritium input function, which can also influence the simulated results.

关键词： North Pacific basin-wide ocean general circulation model tritium input function tritium distributions

Palynological record during the Pleistocene (between 1.05 Ma and 0.36 Ma) from ODP1.4., northern South China Sea

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Science China Earth sciences 2004年第1期47卷 30-36页

作者： HUANG Fei & SUN Xiangjuninstitute of {1. and Paleontology, chinese academy of sciences, Nanjing 21.008, China institute of Botany, chinese academy of sciences, beijing 1.0093, China key laboratory of Marine {1., Ministry of Education, Tongji University, Shanghai 200092, China Correspondence should be addressed to Huang Fei 1. institute of {1. and Paleontology Chinese Academy of Sciences 210008 Nanjing China 2. institute of Botany Chinese Academy of Sciences 100093 Beijing China 3. key {1. of Marine geology Ministry of Education Tongji University 200092 Shanghai China

This paper presents the pollen record from the lower section of ODP1.4. (depth 501.3-225.7 m, ca. 1.05-0.36 Ma). Two pollen zones (PA and PB) and eleven pollen subzones are recognized. Within zone PB, the 1. pollen subzones (PB21.1.) are defined according to the pine, fern and herb variations, and are equivalent to the marine isotope stages 21.1. (MISs 21.1.). The interglacial periods are typified by an increase in pine pollen and fern spores, and a decrease in herbaceous pollen, while the patterning during the glacial periods is just the opposite. During the interglacial periods, pollen assemblages were dominated by pine similar to those of the present day, suggesting that the paleoenvironment of the interglacial periods was similar to that of the present day, whereas the glacial periods are marked by an increase in herbaceous pollen, mainly Gramineae and Cyperaceae, indicating that grassland covered the exposed continental shelf when sea level declined. Increased Artemisia percentages and the highest pine influx during MIS1. may result from a stronger winter monsoon.

关键词： pollen record, Pleistocene, ODP1.4., northern South China Sea.

Dynamic tree-based authenticated group key exchange protocol

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Science China(Information sciences) 2010年第8期53卷 1591-1602页

作者： LI Hui 1.2 , WU ChuanKun 1.& TENG JiKai 1.2 1.State {4. {1. of Information Security, institute of Software, chinese academy of sciences, beijing 1.01.0, China 2 Graduate University of chinese academy of sciences, beijing 1.004., China 1. State key {1. of Information Security Institute of Software Chinese Academy of Sciences Beijing 100190 China2. Graduate University of Chinese Academy of Sciences Beijing 100049 China

Authenticated group key exchange protocols allow a group of users over a public network to establish a shared secret key for the subsequent cryptographic goals. In this paper, we extend BD-II scheme into a dynamic setting, and propose a tree-based authenticated key exchange protocol which is more suitable for dynamic groups in such as ad hoc networks. Our protocol is proven secure in random-oracle model. Additionally, we analyze the costs of our protocols in both communication and computation terms, and compare its performance with three well-known protocols.

关键词： tree-based group key exchange dynamic provable security