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Impact of thickness of GaN buffer layer on properties of AlN/GaN distributed Bragg reflectors grown by metalorganic chemical vapor deposition

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science china(Technological sciences) 2010年第2期53卷 313-316页

作者： WU ChaoMin1, SHANG JingZhi1, ZHANG BaoPing1,2, ZHANG JiangYong1,3, YU JinZhong1,3 & WANG QiMing1,31 Department of Physics and Semiconductor Photonics Research Center, xiamen university, xiamen 361.05, china 2 Pen-Tung Sah Micro/Nano Technology Research Center, xiamen university, xiamen 361.05, china 3 State key laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of sciences, Beijing 100083, china 1. Department of Physics and Semiconductor Photonics Research Center Xiamen University Xiamen 361005 China2. Pen-Tung Sah Micro/Nano Technology Research Center Xiamen University Xiamen 361005 China3. State Key Laboratory on Integrated Optoelectronics Institute of Semiconductors Chinese Academy of Sciences Beijing 100083 China

We studied the impact of the thickness of GaN buffer layer on the properties of distributed Bragg reflector (DBR) grown by metalorganic chemical vapor deposition (MOCVD). The samples were characterized by using metallographic microscope, transmission electron microscope (TEM), atomic force microscopy (AFM), X-ray diffractometer (XRD) and spectrophotometer. The results show that the thickness of the GaN buffer layer can significantly affect the properties of the DBR structure and there is an optimal thickness of the GaN buffer layer. This work would be helpful for the growth of high quality DBR structures.

关键词： MOCVD DBR high-reflectivity nitride

Performance analysis of a noise-normalized FFH/MFSK receiver over Rayleigh fading channels with partial-band noise jamming

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science china(Information sciences) 2011年第1期54卷 129-135页

作者： ZHOU ZhiQiang,LI ShaoQian & CHENG YuFan National key laboratory of science and Technology on Communications,university of Electronic science and Technology of china,Chengdu 610054,china 1. National key laboratory of science and Technology on Communications University of Electronic Science and Technology of China Chengdu 610054 China

Fast frequency hopping can reduce the degradation caused by *** performance of noise-normalized fast frequency-hopped M-ary orthogonal frequency-shift-keying(FFH/MFSK)receivers over frequency nonselective Rayleigh fading channels with partial-band noise jamming is *** of numerical evaluation,a closed-form error probability expression is given based on the theory of complex variables. The simulation results validate the analytical *** is shown that there is an optimum diversity order and the system performance gets better with an increase in the modulation order.

关键词： anti-jamming fast frequency hopping noise normalization combining Rayleigh fading

Adsorption and reduction of palladium (Pd^(2+)) by Bacillus licheniformis R08

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Chinese science Bulletin 2002年第15期47卷 1262-1266页

作者： LIN Zhongyu, ZHOU Chaohui, WU Jianming, CHENG Hu, LIU Bilan, Nl Zimian, ZHOU Jianzhang & FU JinkunState key laboratory for Physical Chemistry of Solid Surface, Department of Chemistry, xiamen university, xiamen 361.05, china State key laboratory for Physical Chemistry of Solid Surface Department of Chemistry Xiamen University Xiamen China

Preliminary study on the mechanism of Pd2+ biosorption by resting cells of Bacillus licheniformis R08 biomass has been carried out by means of chemical kinetics and AAS, TEM, XRD and FTIR methods. The results showed that at 30°C and pH 3.5, when dry R08 biomass powder (800 mg/L) was mixed with Pd2+ (100 mg/L) for 45 min, the rate constant k of biosorption of Pd2+ attained a maximum of 5.97×10-2 min-1 and the half life period of the reaction reached 12 min. The part of Pd2+ adsorbed by R08 biomass was reduced to elemental, cell-bound Pd0 at the same condition. The cell wall of R08 biomass was the primary location for accumulating Pd2+, and aldoses, i. e. hy-drolysate of a part of polysaccharides on the peptidoglycan layer in the acidic medium, serving as the electron donor, in situ reduced the Pd2+ to Pd0.

关键词： Bacillus licheniformis biosorption palladium non-en-zymatically mediated bioreduction FTIR.

Sequential injection spectrophotometric determination of nanomolar nitrite in seawater by on-line preconcentration with HLB cartridge

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Acta Oceanologica Sinica 2010年第1期29卷 100-107页

作者： ZHANG Min YUAN Dongxing HUANG Yongming CHEN Guohe ZHANG Zhen State key laboratory of Marine Environmental science Enviromnental Science Research Center Xiamen University Xiamen 361005 China College of Life science Shaoxing University Shaoxing 312000 China

The unstable state of nitrite results in its very low concentration in seawater, which is below the limit of detection （LOD） of conventional techniques of analysis. Some sensitivity-enhanced methods have been proposed for the determination of nitrite at nanomolar level to illustrate the role of nitrite in the marine nitrogen cycle. However, most of previous reports are not widely accepted, because of their complexity and cost equipment or intensive labor requirement. In this study, a simple automatic system for the determination of nanomolar level nitrite using on-line preconcentration with spectrophotometric detection was described..An Oasis HLB cartridge was adopted to quantitatively enrich the pink-colored azo compound, formed from nitrite via Griess reaction. The cartridge was rinsed with water and ethanol （volume fraction is 55%, the same below）, in turn, then eluted by an eluent containing 50% ethanol and 0.25 M（mol/dm^3） H2SO4, and determined at 543 nm with a 2 cm path-length flow cell. Under the optimized experimental conditions, the calibration curve showed a good linearity in the range of 1.4 85.7 aM, and the LOD （3a） was estimated to be 0.5 nM. The relative standard deviations of 7 measurements were 4.0% and 1.0% for the samples spiked at 7.1 and 28.6 nM, respectively. The recoveries for the different natural water samples were between 92.2%-108.4%. Each HLB cartridge could be reused for at least 50 times. As compared with other SPE methods, the advantages of this method included the free of interference from salinity variation and less sample consuming. The results of the application of the proposed method to natural water showed good agreement with liquid waveguide capillary cell detection method.

关键词： nitrite seawater on-line preconcentration sequential injection solid phase extraction

An initial note on quasi- stationary, cold-core Lanyu eddies southeast off Taiwan Island

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Chinese science Bulletin 2003年第19期48卷 2101-2107页

作者： JING Chunsheng1,2 & LI Li1 1. Third Institute of Oceanography, State Oceanic Administration, xiamen 361.05, china 2. Department of Oceanography, xiamen university, xiamen 361.05, china Third Institute of Oceanography State Oceanic Administration Xiamen China Department of Oceanography Xiamen University Xiamen China

Drifting buoys, satellite altimetry and satellite-derived sea surface thermal images are used to identify the existence of a large cold-core, cyclonic Kuroshio frontal eddy between Hengchun Peninsula and Lanyu, southeast off Taiwan Island around March 1996. The cold eddy accompanies an offshore meander of the Kuroshio near Lanyu, about 70 km and 100 km in horizontal zonal and meridional scales, respectively. The cold eddy is different from normal Kuroshio frontal eddies for its persisting of about 2 months near Lanyu. Supporting evidence suggests that the Kuroshio intruded into the South china Sea (SCS, hereafter) forming a loop-like structure during the persisting period of the cold eddy and that similar eddies occur occasionally in the same location. Compared with the corresponding studies in the Gulf of Mexico, it is suggested that Lanyu cold eddies are SCS analogues of Tortugas eddies found in the southern Straits of Florida. Overshooting of the meandering Kuroshio when it leaves the SCS and effects from conservation of potential vorticity are the possible mechanism of eddy genesis.

关键词：台湾省黑潮暖流涡流寒潮飓风

Evolution of a coastal upwelling event during summer 2004 in the southern Taiwan Strait

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Acta Oceanologica Sinica 2011年第1期30卷 1-6页

作者： ZHANG Caiyun HONG Huasheng HU Chuanmin SHANG Shaoling State key laboratory for Marine Environmental science College of Oceanography and Environmental Sciences Xiamen University Xiamen 361005 China College of Marine science University of South Florida St. Petersburg USA

A coastal upwelling event in the southern Taiwan Strait （STWS） was investigated using intensive cruise surveys （four repeated transects in a month） and satellite data in July and early August 2004. The extensive upwelling-associated surface cold water was first observed in early July （-2.0×10a km2） along the STWS coast. Then, the cold surface water reduced in size by -50% with decreased chlorophyll concentrations after 15 days, indicating the weakening of the upwelling event. At the end of July, the cold surface water disappeared. The temporal variations of the surface cold water and the 3-D hydrography around Dongshan Island are thought to be mainly attributed to the weakened upwelling-favorable southwestern wind, the asymmetric spatial structure of the wind field and the intrusion of warm water from the northern South china Sea.

关键词： coastal upwelling evolution SST ocean color remote sensing Taiwan Strait

Phylogenetic analysis of aerobic anoxygenic phototrophic bacteria and their relatives based on farnesyl pyrophosphate synthase gene

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Acta Oceanologica Sinica 2010年第5期29卷 82-89页

作者： FENG Fuying JIAO Nianzhi DU Hailian ZENG Yonghui State key laboratory of Marine Environmental science Xiamen University Xiamen 361005 China College of Life sciences Innermongolia Agriculture University Huhhot 010018 China

The study aims to reveal phylogenetic and evolutionary relationship between aerobic anoxygenic phototrophic bacteria（AAnPB） and their relatives,anaerobic anoxygenic phototrophic bacteria（AnAnPB） and nonphototrophic bacteria（NPB,which had high homology of 16S rDNA gene with AAnPB and fell into the same genus）,and validate reliability and usefulness of farnesyl pyrophosphate synthase（FPPS） gene for the phylogenetic *** genes with our modified primers and 16S rDNA genes with general primers,were amplified and sequenced or retrieved from GenBank *** contrast to 16S rDNA gene phylogenetic tree,AAnPB were grouped into two clusters and one branch alone with no intermingling with NPB and AnAnPB in the tree constructed on *** branch of AAnPB,in both trees,was located closer to outgroup species than AnAnPB,which implicated that some AAnPB would be diverged earlier in FPPS evolutionary history than AnAnPB and *** AAnPB and NPB were closer located in both trees and this suggested that they were the closer relatives than *** codon usage in FPPS with phylogenetic analysis,the results indicates that FPPS gene and 16S rRNA gene have similar evolutionary pattern but the former seems to be more reliable and useful in determining the phylogenic and evolutionary relationship between AAnPB and their *** is the first attempt to use a molecular marker beside 16S rRNA gene for studying the phylogeny of AAnPB,and the study may also be helpful in understanding the evolutionary relationship among phototrophic microbes and the trends of photosynthetic genes transfer.

关键词： aerobic anoxygenic phototrophic bacteria farnesyl pyrophosphate synthase phylogeny anaerobic anoxygenic phototrophic bacteria nonphototrophic bacteria

Size and support effects for CO oxidation on supported Pd catalysts

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science china Chemistry 2010年第9期53卷 2047-2056页

作者： WANG ZhaoWen,LI Bin,CHEN MingShu,WENG WeiZheng & WAN HuiLin State key laboratory of Physical Chemistry of Solid Surfaces National Engineering laboratory for Green Chemical Productions of Alcohols-Ethers-Esters Department of Chemistry,College of Chemistry and Chemical Engineering,xiamen university,xiamen 361.05,china 1. State key laboratory of Physical Chemistry of Solid Surfaces Xiamen University Xiamen 361005 China2. National Engineering Laboratory for Green Chemical Productions of Alcohols-Ethers-Esters Xiamen University Xiamen 361005 China3. Department of Chemistry College of Chemistry and Chemical Engineering Xiamen University Xiamen 361005 China

Supporting Pd catalysts characterized significant different size distribution were obtained using PdCl2,[Pd(NH3)4](NO3)2 and Pd(acac)2 as ***-resolution transmission electron microscopy(TEM),X-ray diffraction(XRD),in-situ Fourier transform infrared spectroscopy(FTIR) and Raman spectroscopy were used to examine the dispersion of *** performance measurements show that the activities for CO oxidation increase as the Pd particle size decreases and the O2/CO ratio *** activities under oxygen rich conditions are significantly higher than those at near the stoichiometric *** on TiO2 prepared by the Pd(acac)2 precursor is highly dispersed,leading to a considerable activity for CO oxidation at near room *** oxidation on the 1 wt% Pd/TiO2 and under an O2/CO ratio of 1 characterized an apparent activation energy of 36.7 kJ/mol,which is closed to those reported for CO oxidation on the supported Au *** present work demonstrates a high catalytic activity of highly dispersed noble metals,and suggests a promising approach of using noble metals as catalysts with exceeding high efficiency.

关键词： noble metals supported palladium CO oxidation size effect support effect

STUDIES ON“CLUSTER-SURFACE ANALOGY”—CLUSTER MODEL CALCULATIONS FOR CO/Pd CHEMISORPTION SYSTEM

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Journal of Energy Chemistry 1994年第3期 231-243页

作者： XU Xin WANG Nan-QinCHEH Ming-Dan ZHANG Qian-ErState key laboratory for Physical Chemistry in Sur face science Department of Chemistry, xiamen university xiamen, Fujian 361.05

Ab initio calculations with relativistic effective core potential havebeen performed to study Pdand Pd-CO clusters with n ranging from 1 to *** has been focused on what can be done for better cluster modeling ofchemisorption. The calculated electronic Properties of a small cluster can becompared favorably with bulk metal properties. when the multiplicity and thebesis functions in calculatioas are properly chosen according to the metallic con-figuration in the bulk. Reasonably good agreement botween pd-CO cluster andCO/Pd chemisorption system demontrates that the calculation procedure sup-posed in this work may be useful and practical in cluster study of chemisotp-tion.

关键词： Pd STUDIES ON CLUSTER MODEL CALCULATIONS FOR CO/Pd CHEMISORPTION SYSTEM CLUSTER-SURFACE ANALOGY CO