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Systematic distortion in cosmic microwave background maps

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Science china(Physics,Mechanics & Astronomy) 2009年第5期52卷 804-808页

作者： LIU Hao 1,3 &LI TiPei 1,2 1Key Laboratory of Particle Astrophysics,institute of High Energy Physics,chinese academy of sciences,beijing 100049,china 2center for Astrophysics,Tsinghua University,beijing 100084,china 3 Graduate University of chinese academy of sciences,beijing 100049,china Key Laboratory of Particle Astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 China center for Astrophysics Tsinghua University Beijing 100084 China Graduate University of chinese academy of sciences Beijing 100049 China

To minimize instrumentally the induced systematic errors,cosmic microwave background(CMB)anisotropy experiments measure temperature differences across the sky using pairs of horn antennas, temperature map is recovered from temperature difference obtained in sky survey through a map-making *** inspect and calibrate residual systematic errors in the recovered temperature maps is important as most previous studies of cosmology are based on these *** analyzing pixel-ring coupling and latitude dependence of CMB temperatures,we find notable systematic devia- tion from CMB Gaussianity in released Wilkinson Microwave Anisotropy Probe(WMAP)*** detected deviation cannot be explained by the best-fit LCDM cosmological model at a confidence level above 99%and cannot be ignored for a precision cosmology study.

关键词： cosmology cosmic microwave background methods data analysis

Carbazole-containing lightemitting polymers:Properties of excited states

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chinese Science Bulletin 2003年第7期48卷 637-642页

作者： LIN Hongzhen, ZHENG Min, YANG Junlin & BAI Fenglian Laboratory of Organic Solids, center for Molecular Science, institute of chemistry, chinese academy of sciences, beijing 100080, china 1. Laboratory of Organic Solids Center for Molecular Science Institute of Chemistry Chinese Academy of Sciences Beijing 100080 China

A series of light-emitting conjugated polymers alternatively involving carbazole and bivinylene arylene moieties in the main chain were synthesized via Wit-tig-Horner type copolymerization. The photoinduced charge transfer process relating to these polymers was investigated by using the technique of fluorescence spectroscopy. The interaction between excited copolymers and C60 in benzene solution was studied. The fluorescence quenching can be well described by the 搒phere-of-action?mechanism. It is be-lieved that two basic steps are involved in the quenching process, i.e. the diffusion of excitation within the conjugated polymers and the dissociation of the exctions trapped by fullerene. The radius of the sphere-of-action can be related to the excitation diffusion length, which depends on the lifetime of the exciton. The dynamic fluorescence quenching of the copolymers by another quencher, 1,4-dicyanobenzene (DCB) was also surveyed. Copolymers with different chain confor-mations show different temperature effects in the dynamic quenching. A planar conformation is beneficial for the quenching via bimolecular collision.

关键词：共轭发光聚合体咔唑光致能量传递作用范围荧光猝灭

MB_8^(2-) (M=Be,Mg,Ca,Sr,and Ba):Planar octacoordinate alkaline earth metal atoms enclosed by boron rings

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Science china chemistry 2010年第8期53卷 1737-1745,1829-1832页

作者： PU ZhiFeng1,GE MaoFa1 & LI QianShu2 1State Key Laboratory for Structural chemistry of Unstable and Stable Species beijing National Laboratory for Molecular sciences (BNLMS) institute of chemistry,chinese academy of sciences,beijing 100190,china 2center for Computational Quantum chemistry,South china Normal University,Guangzhou 510631,china 1. State Key Laboratory for Structural chemistry of Unstable and Stable Species beijing National Laboratory for Molecular sciences (BNLMS) institute of chemistry Chinese Academy of Sciences Beijing 100190 China2. Center for Computational Quantum Chemistry South China Normal University Guangzhou 510631 China

Complexes involving planar octacoordinate alkaline earth metal atoms in the centers of eight-membered boron rings have been investigated by two density functional theory (DFT) ***82-with D8h symmetry is predicted to be stable,both geometrically and electronically,since a good match is achieved between the size of the central beryllium atom and the eight-membered boron *** contrast,the other alkaline earth metal atoms cannot be stabilized in the center of a planar eight-membered boron ring because of their large *** following the out-of-plane imaginary vibrational frequency,pyramidal C8v MgB82-,CaB82-,SrB82-,and BaB82-structures are *** presence of delocalized π and σ valence molecular orbitals in D8h BeB82-gives rise to aromaticity,which is reflected by the value of the nucleus-independent chemical *** D8h BeB82-structure is confirmed to be the global minimum on the potential energy surface.

关键词： density functional theory octacoordinate alkaline earth metal aromatic molecular orbital

Structures and physical properties of rigid polyurethane foams with water as the sole blowing agent

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Science china chemistry 2006年第4期49卷 363-370页

作者： LI Xiaobin1,2, CAO Hongbin1 & ZHANG Yi1 1. institute of Process Engineering, chinese academy of sciences, beijing 100080, china 2. Graduate School of the chinese academy of sciences, beijing 100039, china 1. institute of Process Engineering Chinese Academy of Sciences Beijing 100080 China 2. Graduate School of the chinese academy of sciences Beijing 100039 China

Rigid polyurethane foams blown by varying water level were prepared in this study. The structures and physical properties of rigid polyurethane foams blown by water were measured with FT-IR, universal testing machine (Instron3365), scanning electron microscope (SEM) and differential scanning calorimeter (DSC). The results show that polyurea and polybiuret were the typical charac- teristics, and the cream time and gel time were shorter for the fully water blown rigid foams than that for the fully cyclopentane blown foams. The density of foam samples decreased from 45.0 kg/m3 to 27.4 kg/m3 with the increase of water level from 3 pph to 7 pph. Compressive strength exhibited the similar behavior with density. The average cell size of foam samples ranged from 241 μm to 356 μm with the increase of water level from 3 pph to 7 pph, respectively. At the same time, poorer dimen- sional stability was encountered with the increase of average cell size due to fast diffusion rate of CO2 out of the foam. The results of thermal analysis show that the glass transition temperature (Tg) shifted to a higher temperature with the increase of isocyanate level when more water was used as chemical blowing agent.

关键词： polyether polyol, polyurethane rigid foam, compressive strength, dimensional stability, cell size, glass transition temperature.

POLYMERIZATION OF ETHYLENE WITH UNSYMMETRIC 2,6-BIS(IMINO)PYRIDINE IRON(Ⅱ)COMPLEX

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chinese Journal of Polymer Science 2002年第3期20卷 205-211页

作者： Zhi Ma Wen-hua Sun Zi-long Li Chang-xing Shao You-liang Hu State Key Laboratory of Engineering Plastics and the center for Molecular sciences institute of chemistry chinese academy of sciences, beijing 100080 china State Key Lab. of Engineering Plast. Institute of Chemistry Chinese Academy of Sciences Beijing 100080 China

An unsymmetric 2,6-bis(imino)pyridine iron(II) complex 1' was synthesized. The relationship between catalyststructure and its activity in ethylene polymerization is discussed. The kinetic behavior of ethylene polymerization and theeffects of polymerization conditions such as temperature, aluminum/iron molar ratio on the activity of catalyst and thecharacteristics of polyethylene were reported. The unsymmetric catalyst 1' has a good catalytic performance of 3.47×10~6 gPE·mol^(-1)·Fe·h^(-1) at 40℃ with aluminum/iron molar ratio = 2500. A dependence of catalyst activity on themethylaluminoxane (MAO) concentration and reaction temperature was found. The molecular weight (MW) of polyethylenewith broad dispersity is about 10~4-10~5 g/mol. The melting temperature and branching of polyethylenes vary with changingreaction temperature and aluminum/iron molar ratio.

关键词： Unsymmetric 2,6-bis(imino)pyridine iron(Ⅱ) complex Ethylene polymerization Catalyst structure Catalytic activity

Analysis of the linkage positions and isomers of monosaccharide units in oligosaccharides by negative secondary ion mass spectrometry in combination with the stereoselective reaction with substituted boronic acid

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chinese Journal of chemistry 1993年第1期11卷 53-58页

作者： YAN,Lin FANG,Yi-Wei institute of chemistry,chinese academy of sciences,beijing 100080 institute of chemistry Chinese Academy of Sciences Beijing 100080

The negative secondary ion mass spectrometry,in combination with the stereoselective derivatizations with substituted boronic acid RB(OH)_2,was used in the analysis of fourteen oligosac- *** mass spectra of the derivatives provide information on their linkage Positions and iso- merism of the individual monoscaccharide *** results indicated that among the derivatives of the oligosaccharides analyzed,those with 1—4 and 1—6 linkages all presented the ion peaks at m/z 287,sometimes one more peak at m/z ***,a relationship was found between the linkage positions and the intensity orders of the derivative ***,the derivatives of the disaccharides with a galactose presented an intense ion peak at m/z 347,and those of oligosaccharides with 1—6 linkage to a galactose at terminal presented the ion at m/z *** the case of oligosaccharides with a fructose residue,characteristic ion of m/z 155 was *** conditions of stereoselective derivatizations and mass spectrometry were studied,in order to obtain a better reproducibility of the mass spectra.

关键词： Analysis of the linkage positions and isomers of monosaccharide units in oligosaccharides by negative secondary ion mass spectrometry in combination with the stereoselective reaction with substituted boronic acid acid

POLYMERIZATION OF p-DIETHYNYLBENZENE INITIATED BY Ni(C≡CC_6H_4C≡CH)_2(PPH_3)_2

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chinese Journal of Polymer Science 2001年第3期19卷 303-309页

作者： Mu-jie Yang Xiao-wei Zhan Department of Polymer Science and Engineering Zhejiang University Hangzhou 310027, china Present address: institute of chemistry, chinese academy of sciences, beijing 100080, china 浙江大学浙江杭州

Homogeneous polymerization of p-diethynylbenzene initiated by nickel acetylide Ni(C ≡ C C_6H_4 C ≡ CH)_2(PPh_3)_2has been investigated in terms of different solvents, addition agents, atmosphere gases, catalyst concentrations, monomerconcentrations and polymerization temperatures. The yield and catalytic efficiency approach 88% and 11. 1 kg polymer/molNi, respectively, under the optimum conditions: [cat] = 0.01 mol/L, [M] = 1.0 mol/L, NEt_3/cat (mol ratio) = 3～5, 1,4-dioxane/toluene (volume ratio) = 1 and T = 25℃ for 5 h. The polymerization rate equation can be expressed as R_p =k_p[M][cat]~2, where k_p= 0.47 L^2. mol^(-2)·S^(-1) (25℃). The overall polymerization activation energy was found to be203 kJ·mol^(-1). Poly(p-diethynylbenzene) so obtained is soluble in THF, CHCl_3 and toluene with weight-average molecularweights as high as 27, 100 and a rich-trans extended π-conjugated polyene chain structure with pendent groups ofp-C_6H_4C≡CH.

关键词： Polymerization p-Diethynylbenzene Nickel acetylide Catalyst

Synthesis of a ball-chain system C_(60) aza-derivative

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chinese Journal of chemistry 1996年第4期14卷 367-369页

作者： WANG, Nai-Xing LI, Ji-Sheng ZHU, Dao-Beninstitute of chemistry, chinese academy of sciences, beijing 100080, china institute of chemistry Chinese Academy of Sciences Beijing 100080 China

Nitrenes generated by thermolysis of alkyl azides were found to add to C60 in chloroben-zene solvent. The product was isolated by means of silica gel chromatography and identified by field desorption mass spectroscopy... 详细信息

关键词： C60 fullerene Cao derivative synthesis

Recent progress in fingerprint recognition

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Progress in Natural Science:Materials International 2006年第3期16卷 231-240页

作者： TIAN Jie, CHEN Xinjian, ZHANG Yangyang, YANG Xin, HE Yuliang, LI Liang, XIE Weihua and ZHENG Zhipeng (center for Biometrics and Security Research, Key Laboratory of Complex Systems and Intelligence Science, institute of Automation, chinese academy of sciences, beijing 100080, china Graduate School of the chinese academy of sciences, beijing 100080, china) [a]center for Biometrics and Security Research Key Laboratory of Complex Systems and Intelligence Science Institute of Automation Chinese Academy of Sciences Beijing China [b]Graduate School of the chinese academy of sciences Beijing China

Fingerprint recognition has been increasingly used to realize personal identification in civilian' s daily life, such as ID card, fingerprints hard disk and so on. Great improvement has been achieved in the on-line fingerprint sensing technology and automatic fingerprint recognition algorithms. Various fingerprint recognition techniques, including fingerprint acquisition, classification, enhancement and matching, are highly improved. This paper overviews recent advances in fingerprint recognition and summarizes the algorithm proposed for every step with special focuses on the enhancement of low-quality fingerprints and the matching of the distorted fingerprint images. Both issues are believed to be significant and challenging tasks. In addition, we also discuss the common evaluation for the fingerprint recognition algorithm of the Fingerprint Verification Competition 2004 (FVC2004) and the Fingerprint Vendor Technology Evaluation 2003 (FpVTE2003), based on which we could measure the performance of the recognition algorithm objectively and uniformly.

关键词： biometrics fingerprint enhancement matching minutia image registration similarity measures.