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Charge order and spin order in Nd_(0.5)Sr_(0.5)Mn_(1.x)(Ga_x, Ti_x)O_3 system

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Science China(physics,Mechanics & Astronomy) 2007年第3期50卷 294-302页

作者： REN QingBao1.2. ZHU WeiTing1. {2. Bo{1. ZHANG YuHeng2.1.department of {2., lishui university, lishui 32.000, China 2.National High Magnetic Field laboratory, university of Science and Technology of China, Hefei 2.002., China 1. department of {1. Lishui University Lishui 323000 China 2. National High Magnetic Field laboratory University of Science and Technology of China Hefei 230026 China

Magnetic properties of Nd_(0.5)Sr_(0.5)Mn_(1.x)(Ga_x, Ti_x)O_3 system (0.04≤x≤0.4) were inves- tigated through magnetization and electron spin resonance (ESR) measurements. It was observed that a small amount of Ti substitution for Mn will destroy the charge-ordering (CO) phase completely and induce the cluster-spin-glass phase in the system, which displays a procedure of collapse of CO and of an enhancement of spin ordering (SO) phase. In contrast, the Ga substitution for Mn induces a melt- ing of CO phase in the system. It was observed that with substitution the CO phase is suppressed gradually and the remanent CO phase is retained all the while, and withal, there is a co-existence of AFM CO phase and FM SO at low temperature. In addition, an abrupt rise of magnetization was observed in M-T curves. We attributed this abnormal phenomenon to a transition from canted AFM SO to FM SO in CO region.

关键词： charge ordering spin ordering antiferromagnetic transition

Variation of reactivity of particulate and sedimentary organic matter along the Zhujiang River Estuary

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Acta Oceanologica Sinica 2003年第4期22卷 557-568页

作者： Chen Jianfang 1.2. Jin Haiyan 1.2. Yin Kedong3, li Yan 1.2.1. Key laboratory of Submarine Geosciences of State Oceanic Administration, Hangzhou 31.01., China. 2. laboratory of Regional Oceanography, Second Institute of Oceanography, State Oceanic Aedministration, Hangzhou,31.01., China 3. department of Biology, {1. Kong {2. of Science and Technology, {1. Kong Kay lab Submarine Geosci State Ocean Adm Hangzhou 310012 Peoples R China State Ocean Adm Inst Oceanog 2 Lab Reg Oceanog Hangzhou 310012 Peoples R China hong Kong Univ Sci & Technol Dept Biol Hong Kong Hong Kong Peoples R China

To investigate organic matter source and reactivity in the Zhujiang River (Pearl River) Estuary and its adjacent areas, particulate organic carbon (POC), particulate hydrolysable amino acids (PHAA), and Chl a during two cruises in July 1.99 and July 2.00 were measured. The highest POC and PHAA concentration was observed in the waters with maximum Chl a. The spectra distribution, relative content (dry weight in milligram per gram), PHAA-C% POC and other indicators such as the ratios of amino acids vs. amino sugars (AA/AS) and glucosamine vs. galactosamine (Glum/Gal) suggested that particulate amino acids in the water column and sediments in the Zhujiang River Estuary were mainly derived from biogenic processes rather than transported from terrestrial erosion. In inner estuary where high turbidity was often observable, organic matter was mainly contributed by re-suspension of bottom sediments with revealed zooplankton, microbial reworked characteristics, which suggest that these organic matters were relatively 'old'. In the estuarine brackish region, organic matter in water column is mainly contributed by relatively fresh, easily degradable phytoplankton derived organic matter. During physical - biological processes within the eastuary, organic matter derived from phytoplankton was subjected to alteration by zooplankton grazing and bacterial reworking.

关键词： organic matter reactivity amino acids the Zhujiang River Estuary

Empirical likelihood confidence regions of the parameters in a partially linear single-index model

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Science China Mathematics 2005年第10期48卷 1333-1348页

作者： XUE liugen~1.& ZHU lixing~2.1. College of Applied Sciences,Beijing {2. of Technology,Beijing 1.002.,China 2. {1. of Mathematics,{2. Kong Baptist {2.,{2. Kong,China 1. College of Applied Sciences Beijing University of Technology 100022 Beijing China 2. department of Mathematics Hong Kong Baptist University Hong Kong China

In this paper, a partially linear single-index model is investigated, and three empirical log-likelihood ratio statistics for the unknown parameters in the model are suggested. It is proved that the proposed statistics are asymptotically standard chi-square under some suitable conditions, and hence can be used to construct the confidence regions of the parameters. Our methods can also deal with the confidence region construction for the index in the pure single-index model. A simulation study indicates that, in terms of coverage probabilities and average areas of the confidence regions, the proposed methods perform better than the least-squares method.

关键词： partially linear single-index model, empirical likelihood, confidence region, chi-square distribution, coverage probability.

Prediction for RNA planar pseudoknots

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Progress in Natural Science:Materials International 2007年第6期17卷 717-724页

作者： li Hengwu1.2. Zhu Daming1. liu Zhendong1.and li hong2.1. School of Computer Science and Technology, Shandong {1., Jinan 2.01.0, China 2. {2. of Computer, Shandong Economic {1., Jinan 2.001., China) [a]School of Computer science and Technology Shandong University Jinan China [b]department of Computer Shandong Economic University Jinan China

Based on m-stems and semi-extensible structure, a model is presented to represent RNA planar pseudoknots, and corresponding dynamic programming algorithm is designed and implemented to predict arbitrary planar pseudoknots and simple non-planar pseudoknots with O(n4) time and O(n3) space. The algorithm folds total 2.5 sequences in the Pseudobase database, and the test results indicate that the algorithm has good accuracy, sensitivity and specificity.

关键词： algorithm RNA secondary structure pseudoknot dynamic programming.

Ability of Agrogyron elongatum to accumulate the single metal of cadmium, copper, nickel and lead and root exudation of organic acids

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Journal of Environmental Sciences 2001年第3期13卷 368-375页

作者： YANG hong 1. Jongathan W.C.Wong 2. YANG Zhi min\+1. ZHOU li xiang 1.1. College of Science, Nanjing Agricultural {1., Nanjing\ 2.1}095, China. 2. {2. of Biology, hong Kong Baptist {1., China) College of Science Nanjing Agricultural University Nanjing 210095 China.

Agrogyron elongatum were grown in nutrient solution containing moderate to high amounts of separate heavy metal of Cd, Cu, Ni and Ph in a greenhouse for a 9 - day. Cd, Cu, Ni and Ph generally led to decrease in the elongation of roots although the length of seedlings exposed to Cd and Ph at 0.05 and 0.5 mg/l showed to be slightly greater than that of controls. Of the four metals in the experiment, Ph was absorbed and accumulated to the highest level, with the concentrations of 92.54 mg/kg dry weight (DW) in roots and 1.683 mg/kg DW in shoots. Cd was moderately accumulated in Agrogyron elongatum, but the maximum bioaccumulation coefficients (BCs) for roots and shoots were observed. The patterns for Cu and Ni uptake and distribution in plants differed from those of Ph and Cd, as it was showed that the shoot accumulation of Cu and Ni was significantly higher than in roots. A. elongation had the highest Ni concentration in shoots (302.1.mg/kg DW) at the external concentration of 2.0 mg/l. Cu ranked second, with a shoot concentration of 1.2.0 mg/kg DW when 50 mg/l Cu in solution was applied. For the four trace elements tested, the highest concentrations in shoots decreased by the order of Ni > Cu > Ph > Cd (mg/kg DW), and those in roots were Ph > Cd > Ni > Cu (mg/kg DW). Malic, oxalic and citric acids exuded by roots exposed to 1.and 50 mg/l of the metals were detected. Release of organic acids from plants significantly differed among the metal treatments. Cu was most effectively in inducing root exudation of the three types of organic acids. Cd, and Ni were also the inducers of secretion of malic and oxalic acids. With reference of Pb, a small amounts of malic and oxalic acids were detected in the root exudates, but few quantities, of citric acid were. found. However, no correlation between alternations in root exudation of organic acids and metal accumulation could be established.

关键词： heavy metal organic acid Agrogyron elongation hyperaccumulation

Utilization of a spiropyran derivative in a polymeric film optode for selective fluorescent sensing of zinc ion

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Science China Chemistry 2006年第3期49卷 246-255页

作者： ZHANG Ying1. SHAO Na1. YANG Ronghua1. lI Ke’an1. lIU Feng1. CHAN Winghong{1. MO Tian2.1. College of Chemistry and Molecular Engineering, Peking university, Beijing 1.0871. China 2. {2. of Chemistry, hong Kong Baptist university, hong Kong, China 1. College of Chemistry and Molecular Engineering Peking University Beijing 100871 China 2. department of Chemistry Hong Kong Baptist University Hong Kong China

A new spiropyran derivative was synthesized and first utilized in a polymericfilm-based optical sensor for zinc ion. Spiropyrans, combining the characteristics of metal bindingand signal transduction, show potential function in the design of optical chemical sensors(optodes) toward metal ions. When embedded in a plasticized poly (vinyl chloride) (PVC) membrane,the newly synthesized spiropyran derivative 1.exhibits obvious fluorescence enhancement at 630 nm inthe presence of zinc ion in aqueous solution. With the optimum condition described, the optodemembrane responds to zinc ion over a dynamic range of 4.94x1.^(-7) to 4.1.x1.^(-4)mol·l^(-1., witha detection limit of 1.51.1.^(-7) mol·l^(-1.. The membrane not only displays excellentphotostability, reproducibility and reversibility, but also exhibits high selectivity toward zincion over transition metal ions including Hg^(2.), Cd^(2.), Pb^(2.), Cu^(2.), Fe^(3+) and commoncationic ions presented in the physiological fluids.

关键词： spiropyran, sensor, PVC membrane, zinc ion, fluorescent spectroscopy.

latest cosmological constraints on Cardassian expansion models including the updated gamma-ray bursts

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Research in Astronomy and Astrophysics 2011年第9期11卷 1019-1030页

作者： Nan liang Pu-Xun Wu Zong-hong Zhu department of Astronomy Beijing Normal University Beijing 100875 China Center for High Energy physics Peking University Beijing 100871 China Center of Nonlinear Science and department of {1. Ningbo University Ningbo 315211 China

We constrain the Cardassian expansion models from the latest observa- tions, including the updated Gamma-ray bursts （GRBs）, which are calibrated using a cosmology independent method from the Union2.compilation of type Ia supernovae （SNe Ia）. By combining the GRB data with the joint observations from the Union2.SNe Ia set, along with the results from the Cosmic Microwave Background radia- tion observation from the seven-year Wilkinson Microwave Anisotropy Probe and the baryonic acoustic oscillation observation galaxy sample from the spectroscopic Sloan Digital Sky Survey Data Release. we find significant constraints on the model oarameters of the original Cardassian model ΩM0=0.2.2.0.01.^0.01.,n=0.03-0.05^＋0.05 and n=-0.1.-3.2.^＋0.2.,β=0.76-0.58^＋0.34 of the modified polytropic Cardassian model, which are consistent with the ACDM model in a l-or confidence region. From the reconstruction of the deceleration parameter q（z） in Cardassian models, we obtain the transition redshift ZT = 0.73 ± 0.04 for the original Cardassian model and ZT = 0.68 ± 0.04 for the modified polytropic Cardassian model.

关键词： gamma-rays bursts -- cosmology cosmological parameters

Characteristics of vertical ozone distribution in the lower troposphere in the Yangtze River Delta at lin'an in the spring of 2.01

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Science China Earth Sciences 2005年第9期48卷 1519-1528页

作者： ZHENG Xiangdong1. CHAN Chuenyu2. CUI hong2. QIN Yu3, CHAN loyan2. ZHENG Yongguang3 & lEE Yusiang2.1. Chinese Academy of Meteorological Sciences, Beijing 1.0081. China 2. {1. of Civil and Structural Engineering, hong Kong Polytechnic university, Hung Hom, hong Kong, China 3. {1. of Atmospheric Sciences, Peking university, Beijing 1.0871. China 1. Chinese Academy of Meteorological Sciences 100081 Beijing China 2. department of Civil and Structural Engineering Hong Kong Polytechnic University Hung Hom Hong Kong China 3. department of Atmospheric Sciences Peking University 100871 Beijing China

We analyzed vertical distributions of ozone (O3) in the lower troposphere (< 5 km above ground) at lin’an (1.9.75°E, 30.30°N), Zhejiang Province using electrochemical concen- tration cell (ECC) ozonesonde data obta... 详细信息

We analyzed vertical distributions of ozone (O3) in the lower troposphere (lin’an (1.9.75°E, 30.30°N), Zhejiang Province using electrochemical concen- tration cell (ECC) ozonesonde data obtained from February 2.0}to April 1., 2.01. The results showed that the vertical O3 distributions are controlled by metrological conditions and the char- acteristics of O3 profiles are related to those of wet bulb potential temperature and wind field. O3 below 2.km showed that the strongest variability and enhanced O3 mixing ratios were associated with easterly winds that blow pollutants from the upwind source region of the Yangtze River Delta (YRD) region. Vertical O3 profiles below 5 km can be grouped into 5 categories: (1. peak mixing ratio type, (2. well-mixed type, (3) layered-structure type, (4) episodic pollution type and (5) alti- tudinal increasing type. Vertical distributions of O3 affected by regional transport of polluted air masses were investigated. Transport of polluted air from high latitudes of northern China, ac- companying subsiding motion of air and stagnant atmospheric conditions are important factors that lead to high mixing ratios of O3 at lin’an. The stagnant atmospheric conditions associated with a continental high pressure system and pollution plume transported from the YRD and cen- tral-eastern China also lead to regional accumulation of O3 and high O3 mixing ratio at lin’an. long-range transport of O3 and pollutants from the Pearl River Delta in South China and in-situ O3 formation also resulted in elevated O3 mixing ratios at around 1.km altitudes and layered O3 distribution in the lower troposphere.

关键词： vertical ozone distribution, lower troposphere, Yangtze River Delta, lin'an.

Determination of Young's modulus by nanoindentation

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Science China(Technological Sciences) 2004年第4期47卷 398-408页

作者： MA Dejun1. Chung Wo Ong2. lIU Jianmin1.& HE Jiawen3 1. Surface Engineering Research Institute, CMES, Beijing 1.0072. China 2. department of Applied {1. and Materials Research Center, The {2. Kong Polytechnic university, {2. Kong, China 3. State Key laboratory for Mechanical Behavior of Materials, Xian Jiaotong university, Xian 71.049, China 1. Surface Engineering Research Institute CMES 100072 Beijing China 2. department of Applied {1. and Materials Research Center The Hong Kong Polytechnic University Hong Kong China 3. State Key laboratory for Mechanical Behavior of Materials Xi’an Jiaotong University 710049 Xi’an China

A methodology for determining Youngs modulus of materials by non-ideally sharp indentation has been developed. According to the principle of the same area-to-depth ratio, a non-ideally pyramidal indenter like a Berkovich one can be approximated by a non-ideally conical indenter with a spherical cap at the tip. By applying dimensional and finite element analysis to the non-ideally conical indentation, a set of approximate one-to-one relationships between the ratio of nominal hardness/reduced Youngs modulus and the ratio of elastic work/total work, which correspond to different tip bluntness, have been revealed. The nominal hardness is defined as the maximum indentation load divided by the cross-section area of the conical indenter specified at the maximum indentation depth. As a consequence, Youngs modulus can be determined from a nanoindentation test only using the maximum indentation load and depth, and the work done during loading and unloading processes. The new method for determining Youngs modulus is referred to as pure energy method. The validity of the method was examined by performing indentation tests on five materials. The experimental results and the standard reference values are in good agreement, indicating that the proposed pure energy method is a promising substitution for the most widely used analysis models at present.

关键词： Young's modulus, nanoindentation, nominal hardness, indentation work.