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Table of Content

    24 May 1999, Volume 20 Issue 5
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    Articles
    Giant Magnetoresistive Nanocrystalline Films of La1-xSrxMnO3Prepared by Sol gel Method
    ZHANG Zhi-Li, WANG Zhe-Ming, HUANG Yun-Hui, CHENG Fu-Xiang, LIAO Chun-Sheng, GAO Song, YAN Chun-Hua
    1999, 20(5):  665-669　. 
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    The nanocrystalline films of perovskite like manganites La1-xSrxMnO3(LSMO, x= 0～0.6 ) on the single silicon(100) substrates have been fabricated by sol gel method. The annealing dependence of the phase formation, grain size and film morphorlogy have been investigated. The measurement on the magnetoresistance of the films with standard four electrode method shows a widened peak of resistance for each sample due to the boundary effect and a MR value of about -30% at room temperature in6Tmagnetic field for the sample La0.7Sr0.3MnO3.
    Synthesis and Characterization of High quality Mesoporous Molecular Sieve MCM-41s
    XU Yi-Ming
    1999, 20(5):  670-674. 
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    Siliceous MCM-41 samples with two different pore size and metal substituted MCM-41 samples with different metals have been synthesized at different pH of the mixture, and characterized by X-ray powder diffraction and nitrogen adsorption analysis. The results show that all the samples exhibit a typical XRD diffraction of MCM-41 and an adsorption isotherm of type Ⅳ, but there exists a considerable amount of amorphous siliCA In the samples. The sample prepared at pH=11(MCM-3) shows the best in quality among the others, and has less content of amorphous silica phase. When the MCM-3 is regarded as a standard, the sample prepared without pH adjustment contains only 36% of pure MCM-41 crystallites, while the sample prepared at pH=10.5 has 84% of pure MCM-41 phase. It has also been observed that the quality of the resulted samples is decreased when a shorter chain surfactant is used. When the metal substituted M-MCM-41 (M=Al, Mn, Fe, V) is prepared at pH=11, their quality can be improved. However, the diffraction intensity of d100phase is still lower than that of the corresponding siliceous MCM-41, and decreases accordingly from Al to V.
    The Synthesis of Mesoporous Molecular Sieve MCM-48
    CAI Qiang, ZHANG Hui-Bo, LIN Wen-Yong, PANG Wen-Qin
    1999, 20(5):  675-679. 
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    Mesoporous molecular sieve MCM-48 was prepared hydrothermally with CTAB, NaOH, TEOS as source materials. Characterization results obtained from the determination of XRD, TEM, N2-adsorption, IRspectra and TG-DTAshow that the products possess similar structure properties as those reported in literatures. Various synthesis parameters, including crystallization time, crystallization temperature and starting gel composition, have been studied. It was found that the crystallization temperature of 373K was preferable, lower temperature leading to weak crystallinity, higher temperature leading to amorphous material. Crystallization time of 3d was found suitable for MCM-48 formation, shorter time resulting in a low crystallinity. The influence of composition features such as n(H2O)/n (SiO2) and n(CTAB)/n(SiO2) on the product was studied.
    The Preparation of Self assembled Films of C60on Ethyldiamine modified Glass Surface and Its Photoluminescence
    LI Tian-Bao, LI Xin-Hai, HUANG Ke-Xiong, JIANG Han-Ying, LI Jing, CAI Zhi-Guang, LI Jun, ZHAO Shan-Kai
    1999, 20(5):  680-683. 
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    Anew self assembled monolayer and dilayer films were prepared by the reaction of C60with ethyldiamine modified glass surface and with ethyldiamine modified C60self-assembled monolayer surface, respectively. The films were examined by XPS and LDI-TOF-MS etc. The results show that C60has been bound firmly to the ethyldiamine modified glass surface. The photoluminescence spectra of the self assembled films was measured, and it was found that a broad photoluminescence peak centred at 680 nm which is different from the photoluminescence peak of C60.
    Hydrothermal Synthesis and Transport Properties of Nanocrystalline (CeO2)1-x(BiO1.5)xSolid Solution
    LI Guang-She, MAO Ya-Chun, LI Li-Ping, FENG Shou-Hua, WANG Min-Qiang, YAO Xi
    1999, 20(5):  684-689. 
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    By means of XRD and XPS measurements, the structural characteristics and valence states of a series of nanocrystalline solid solutions(CeO2)1-x(BiO1.5)x(x =0.0～0.50) synthesized under mild hydrothermal conditions at 240 ℃ were investigated. The solution limit of Bi2O3in ceria is as high as ca . 50 %. XRD data showed that all solid solutions crystallized in single phase cubic fluorite type structure. This result is different from the solid state reaction routes. The average grain size of all solid solutions was within a narrower range of 10～18 nm. XPS data gave evidence of the presence of Bi(Ⅲ) and Ce(Ⅳ) in all doped ceria. When the content of dopant Bi2O3in ceria was lower than the limit, air firing of the as made doped ceria up to 800 ℃ did not lead to any structural transformation. For the solid solution of (CeO2)0.5(BiO1.5)0.5, sintering it in air at 800 ℃ would cause the limit exceeded as well as segregation of an unknown phase. The ionic conduction measured by impedance spectroscopy showed that the solid solutions with bismuth content lower than the limit exhibited only the bulk conduction. The bulk conduction of solution(CeO2)0.6(BiO1.5)0.4was due to oxide ions and the grain boundary to silver from the electrode.
    Synthesis and Structure of a 2D Woven Network Structure Supramolecule Complex Containing 72-Membered Macrocycles
    LIU Hong-Ke, SUN Wei-Yin, ZHU Hai-Liang, TANG Wen-Xia
    1999, 20(5):  690-692. 
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    Anew flexible aryl heterocyclic tripodal ligand: 1,3,5-tris(imidazol-1-ylmethyl)-2,4,6-trimethylbenzene(titb) was prepared. The titled complex {Cu3(dien)3(titb)2(ClO4)6?(CH3CN)0.5(H2O)0.25}n , where dien=diethylenetriamine, was synthesised by two different methods. The complex crystallizes in triclinic system, space group P2 with a = 1.3630(3) nm , b =1.5837(2) nm, c =2.1105(3) nm, α =70.860(10)°, β =86.700(10)°, γ = 64.900(10)°, V =3.8797(11) nm3, Z =2, Dc=1.577 g/cm3, F (000)=1905, R = 0.0586 , wR2= 01359 , S =0.948, Δρmax=1.190×103e/nm3, Δρmin=-0.472×103e/nm3. There are two kinds of conformation of the titb ligand in the structure of the titled complex, one is cis, trans, trans conformation, the other is cis, cis, cis conformation. Each Cu(dien)2+unit binds with two titb ligands to form a two dimensional woven network structure containing 72-membered macrocycles.
    Synthesis of Low Si/Al β-Zeolite by Using Nucleation Gel
    ZHOU Qun, LI Bao-Zong, QIU Shi Lun, PANG Wen Qin
    1999, 20(5):  693-695. 
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    β-Zeolite was synthesized by using nucleation gel with minimal use of TEAOH and characterized by XRD, 29SiMASNMR and thermal analysis. The results show that β-zeolite possesses aluminium rich framework, and the acid sites of β-zeolite are mainly occupied by sodium ions.
    183WNMR Chemical Shift Characteristic Patterns of the Keggin Trisubstituted Polyoxoanions
    LIU Jing-Fu, WANG Xiao-Hong, MA Jian-Fang, MENG Lu, YANG Qi-Hua
    1999, 20(5):  696-698. 
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    The reaction of SiW9O3410-and GeW9O3410-with metal cations leads to Keggin trisubstituted polyoxoanions. Areview of all known trisubstituted Keggin anions demonstrates characteristic patterns of 183WNMR chemical shifts.
    Quantitative Analysis by Solid-phase Microextraction in Nonequilibrium Situations
    WANG Yi-Ru, WANG Xiao-Ru, Frank S. C. Lee
    1999, 20(5):  699-703. 
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    Solid-base microextraction technique has the advantages of a high efficiency, sensitivity, sinple operation and solvent free An optical fiber coated with 100μm Ennpolyd ethylsiloxane is used to extract 10 PAHs Since the absorption rate is stable w ithin 60min before equilibrium，the quantitative analysis may be realized in nonequilibrium situations The linear concentration、range from 0. 1μg/L to 100μg/L，the detection lin its are in the range of 0. 01-0. 03μg/L，the recoveries crew ithin 80% and 100%，and relative standard deviatants are below 20% for these PAHs
    Studies on an Immunosensor of Album in Based on Surface Plasmon Resonance
    ZHAO Xiao-Jun, MU Ying, WANG Zhen, ZHANG Han-Qi, JIN Qin-Han, XU Han Ying
    1999, 20(5):  704-708. 
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    A practical and simple immunosensor based on surface plasmon resonance(SPR) technique has been developed to determine the albumin antigen. The SPRdevice was different from popular SPR instrument that modulated angle of incident light at fixed excitation wavelength. The device used in the experimental process is designed on the basis of fixing the angle of incident light and measuring the change of resonant wavelength. The protein A was chosen as the substrate membrane because it can not only form a stable complex with gold, but also form complex with ordinary antibodies. The process of combination between gold and protein Awas monitored, and the kinetic adsoption constant is 23×105L·mol-1·s-1. The other combination processed, such as protein Aand albumin antibody, and albumin antibody and antigen had also been studied in real time through observing the change of resonant wavelengths in SPR spectra. The kinetic adsoption constants of all process had been obtained. Using the citrate buffer to rinse the sensing surface, the complex of antibody and antigen could be rinsed out from protein A, and protein Acould be recovered. The relationship between concentrations of albumin antigen and changes of resonant wavelength is linear in the range of 0.02-10 mg/mL. The amounts of albumin antigen in the urine of diabetics have been determined with the SPR sensor. The results are in good agreement with those obtained with standard method.
    Studies on an Immunosensor of Albumin Based on Surface Plasmon Resonance
    CAO Ying, LI Yi-Jun, HE Xi-Wen
    1999, 20(5):  709-712. 
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    The possibilities of neutral red (NR) as DNA interacting mode spectroscopic probe instead of ethidium bromide (EB) is investigated in th is paper based on the studies of interaction of phenoth iozine drugs with DNA by EB probe. The result indicates that as DNA interacting mode probe, NR could match with EB. And with lower toxicity and higher stability than EB, NR has good potentialities to be used as interacting mode spectroscopic probe of DNA.
    Computerized Scanning Voltammetric Detector for Capillary Electrophoresis
    WANG Li-Shi, YANG Xiao-Yun, MO Jin-Yuan, ZOU Xiao-Yong
    1999, 20(5):  713-716. 
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    This work describes the development of a scanning voltammetric detector for capillary electrophoresis. The scanning electrode potential waveform generation and the current signal acquisition are controlled by a microcomputer interfaced with a home-made card which is equipped with 12 bit digital-analog converter(D/A) and a 12 bit analog-digital converter (A/D). The D/A is connected to a Ag/AgCl reference electrode and used to control the cell potential via a voltammeter, and the A/D is connected to the working electrode for data acquisition. The methods of potential control and signal acquisition are discussed. An example of separating mixture of p-diphenol and pyrocatechol is demonstrated. The results obtained are satisfactory.
    Studies on Intrazeolite Electron Transfer Mechanism of Zeolite modified Electrodes
    JIANG Yan-Xia, SONG Wen-Bo, LIU Ying, Lü Nan, ZOU Ming-Zhu, XU Hong-Ding, ZHANG Ai Ling
    1999, 20(5):  717-721. 
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    This paper is concerned with the mechanism of intrazeolite electron transfer in zeolite modified electrodes(ZMEs) where the zeolite have been modified with polyaniline. First, data were obtained from ZMEs prepared with zeolite Yloading aniline and the electropolymerizing of anilines was performed by cyclic voltammery. Polyaniline might not leak out from zeolite due to the bulk size of polyaniline being bigger than the channel of zeolite Y. At the absence of electron transfer mediators, the Pan +Y ZME showed the expected presence of electron hopping of adjacent polyaniline cations. Second, the data were obtained for the determining Cd 2+and ascorbic acid using Pan+Y-ZME. The Cd2+might not be preconcentrated at open circuit and could be done at constant potential. At the absence of ion exchange between zeolite and surrounding electrolyte the electron transfer was performed via the electron hopping, i.e . by an intrazeolite mechanism; rather than by an extrazeolite mechanism. In addition, the ascorbic acid molecule and its anion could not cross zeolite film to base electrode therefore, its current was conducted also by the electron hopping between the chains of polyaniline. Experimental results indicate that the electron transfer of Pan+Y-ZME was dominated by intrazeolite processes.
    Studies on Synthesis, Structure and Antitumor Activities of Analogues of Papaver Somniferum Pollen Tridecapeptide
    XU Jia-Xi, JIN Sheng
    1999, 20(5):  722-726. 
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    Five analogues and five segments were designed and synthesized by using solid phase synthesis method according to separated papaver somniferum pollen tridecapeptide with antitumor activities as leading peptide. Their primary secondary structures in solution were determined by CD spectra and their inhibitive activities to human liver and mammary gland cancer cells were assayed by MTT method. The relationship of structure activity was studied and discussed.
    Studies on the Peptidic Inhibitors of Trypsin
    QI Jie, WANG Li-Ping, FANG Rui, ZHOU Hui, LI Wei
    1999, 20(5):  727-730. 
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    Trypsin was screened in a phage displayed 15-residue peptide library for three rounds basically according to the method described by G. P. Smith. To improve the effectiveness and specificity of screening, the mothod was modified as follows. (1) During the whole screening, trypsin was kept in 0.1mol/L HEPES/20 mmol/L CaCl2buffer(pH7.6) in order to remove most(if not all) of trypsin substrates from the peptide library.(2) Phages binding to the active site of trypsin(potential inhibitors of trypsin) were specifically eluted with trypsin inhibitor BPTI. After three rounds of screening, the potential inhibitors of trypsin were riched. Eighteen of the insert peptide sequences were determined. The result showed that the P1' residues and residues flank the scissile bonds in inhibitors are both important for the inhibitory activities. Compared with the naturally occurring inhibitors of trypsin, a 9-residue peptide DGCCRAQIT was synthesized and its inhibition constant to trypsin was determined to be 89±10 mmol/L.
    Studies on Mechanism of SO4·-Induced Formation ofRadicals Containing Sulphur Three electron Bond
    XU Ye-Ping, LI Quan-Xin, SONG Qin-Hua, SUN Hai-Hong, YAO Si-De, YU Shu-Qin, CHEN Cong-Xiang, MA Xing-Xiao
    1999, 20(5):  731-735. 
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    The oxidation mechanism of D-methioine(Met), L-methioine-methyl ester(MME) and Met-Met dipeptides by SO4·-was investigated by using 248nm laser photolysis of K2S2O8and absorption spectrum. The presence of three electron radical cation intermediated [S∴S]+、[S∴N]+and [S∴O] were observed by transient absorption spectra. The results are compared to those of pulse radiolysis. Adetail oxidation mechanism of sulphur containing amino acids was proposed.
    Synthesis of Some Antagonists of PAF of MK 287's Kind
    LIN Hui, SHI Hong-Xin, MandvillG., BlochR
    1999, 20(5):  736-740. 
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    Trans 2,5-diaryltetrahydrofuran is a potent antagonist of platelet activating factor. It is obtained in high stereoselectivity by the reactions of arylation, oxidation, arylation, cyclization, hot decomposition and hydrogenation starting from (±)4,10-dioxatricyclo[5,2,1,02,6]-dec-8-ene-3-ole and PhTi(OPr-i)3.
    Synthesis and Preliminary Bio-activity Studies of α-Pyrazyl-N phenyl-α-aminophosphonates
    ZHANG Ke-Sheng, MU Lin-Jing, LONG Yun-Xian
    1999, 20(5):  741-743. 
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    Aseries of α-pyrazyl-N-phenyl-α-aminophosphonates was synthesized by the reaction of phosphites with Schiff bases prepared through condensation of substituted anilines with 5-chloro-1-benzyl-3-methyl-4-pyrazylaldehyde. The reaction can be easily carried out without solvent. The two alkoxyl groups linking to phosphorus atom show unequivalent behavior in 1HNMR. The structures of compounds were confirmed by IR, 1HNMR and elemental analysis. The preliminary bioassay shows that some of them possess good fungicide and anti virus activities on some plants.
    Selection of Peptide Ligands Binding to Fibroblast Growth Factor from a Phage Peptide Library
    LIU Ying, FAN Hong-Kuan, ZHOU Hui, WANG Li-Ping, SHI Yu-Hua, LI Wei
    1999, 20(5):  744-746. 
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    Fibroblast growth factor(FGF) is known to bind to its cell-surface receptor in a heparin dependent manner. By mimicking this in vivo process, we designed a novel screening strategy for the identification of FGFligands that bind to the receptor binding region of FGF. After three cycles of selection, the phage recovery increased from 3.1×10-4% to 3.3×10-3%. The DNA inserts of phage clones were sequenced and a group of related peptide sequences were identified. Compared with a key FGF binding loop on the receptor (aa.342～357), these peptide sequences show similarities at several positions. Further ELISA experiment demonstrates that some phage containing these sequences can specifically bind to FGF. And cell proliferation assay suggest that the synthesized peptide can strongly inhibit the mitogenic activity of a FGF. Therefore, these peptides may specifically block the receptor binding to FGFand have the potential of becoming therapeutic agents as FGF antagonists.
    Synthesis and Bioactivity of Substituted Benzaldehyde Oxime Tetramethylcyclopropanecarboxylates(Ⅲ)Synthesis and Bioactivity of Substituted Benzaldehyde Oxmie Tetram ethylcyclopropanecarboxylates
    MA Jun-An, HUANG Run-Qiu, CHAI You-Xin
    1999, 20(5):  747-749. 
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    Twenty of new substituted benzaldehyde oxime tetramethylcyclopropane carboxylates were synthesized. The preliminary bioassays indicated that compounds 5m and 5n showed high insecticidal activity.
    Preparation of Europium doped Porous Silicon by Constant potential Electrolysis and Photoluminescence of Porous Silicon∶Eu
    GONG Meng-Lian, ZENG Chun-Lian, SHI Jian-Xin, WONG Waikwok, CHEAH Kokwai, ZHENG Wan-Hua 
    1999, 20(5):  750-753. 
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    Anovel electrochemical approach, constant potential electrolysis and a new electrolyte system, rare earth nitrate supporting electrolyte substance nonethanol organic solvent, for doping of porous silicon(PS) with europium were reported. By this approach and system, the doping products were well controlled, and a high concentration of Eu(about 1021/cm3) was doped into PS. The effects of solvents, applied voltage, concentration of Eu(NO3)3and doping time on photoluminescence of Eu doped PS were investigated, and the optimum doping conditions were optimized. PS∶Eu prepared under suitable conditions was found to emit much more intense visible room temperature luminescence with blue shift in wavelength than that of corresponding PS wafer. The photoluminescence mechanism for PSand PS∶Eu was also discussed.
    Travelling Waves in an Open Quadralic Autocatalytic Chemical System Coupled with the Quadralic Decay Reaction
    FENG Chang-Gen, XU Shi-Ying, LIU Zhao-Miao, ZENG Qing-Xuan, ZHANG Rui
    1999, 20(5):  754-758. 
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    Theoretical model of an open quadralic autocatalytic chemical reaction system coupled with the quadratic decay reaction is set up. Through the kinetics analysis, the stability of the two stationary states is found. The estimation of the solution for the initial value and bounds problem is established, and a necessary condition for travelling waves to exist is μ≥φ . The minimum speed of the chemical waves are given, that is cmin=2 δ(μ-φ) . The effect of open quadralic decay reaction on the patterns of the chemical waves is also given. With the increase of the decay parameter, the quadratic decay reaction become progressively a decisive element of wave patterns in the reaction diffusion system.
    Studies on Demulsification Mechanism of Demulsifier for the Three compound Combination Flooding Effluent Emulsions
    KANG Wan-Li, SHAN Xi-Lin, LONG An-Hou, LI Jun-Gang
    1999, 20(5):  759-761. 
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    The effects of demulsifiers on interfacial tensions and membrane strength were studied for the model and effluence systems from the three compound combination flooding field. The interfacial tensions owned by the two compound combination system decreased but those owned by the three compound combination system increased with increasing the demulsifier concentrations. Membrane strength decreased with the increase of demulsifier. The demulsification mechanism of demulsifier is suggested that demulsifier partially replaces the stabilizers and greatly decreases the intensity of interfacial film.
    Theoretical Studies on the Structures and Electronic Spectra of Various Possible Isomers of C70O2
    XIA Shu-Wei, SHANG Zhen-Feng, CHEN Zhong-Fang, CHEN Lan, PAN Yin-Ming, ZHAO Xue-Zhuang, TANG Ao-Qing, FENG Ji-Kang
    1999, 20(5):  762-767. 
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    Various possible isomers of C70O2were studied by using AM1, PM3 and INDO methods. Forty five isomers of C70O2were investigated on the basis of the most stable structure of C70O . The calculated results indicate that the structure of C70O2in which the two oxygen atoms are added to the two different 66 bonds of the same six membered ring to form epoxide at the pole of C70is the most stable. The differences of energy between the isomers of C70O2in which the two oxygen atoms are added to α, α; α, β; β, β bonds and the one in which the two oxygen atoms are added to α, γ; α, ε; β, γ; β, ε bonds are about 60-80 kJ/mol. The former is more stable than the latter. By using the optimized geometries, the electronic spectra of C70O2were calculated by INDO/CI and compared with those of C70and C70O.
    A Study of New Solid Electrolytes Based on Urea and Thiourea
    ZHAO Di-Shun, ZHANG Xing-Chen, ZHOU Qing-Ze, LI Hui-Yong, ZHANG Yue, XIONG Pei-Wen
    1999, 20(5):  768-771. 
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    New solid electrolytes based on urea and thiourea have been synthesized. Their ionic conductivity detected by electronic conductivity instrument is higher than 6.84×10-3S·cm-1at room temperature. The main factors influencing the ionic conductivity are analyzed. These are amorphous solid solution. The thiourea changes to ammonium thiocyanate, which can ionize and conduct in the solid electrolyte.
    Interrelation of Carbon Numbers in Microemulsion with Nonionic Surfactant
    TENG Hong-Ni, SUN Yong, HUANG Bin, KONG Bin, CHEN Zong-Qi 
    1999, 20(5):  772-776. 
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    The interrelation of carbon numbers was studied in microemulsions containing nonionic surfactant, n-alcohol, n-hydrocarbon and water by construction of pseduo ternary phase diagrams. Mixtures of the surfactant, alcohol and hydrocarbon were titrated at 30 ℃ with water to the points of turbidity and clarity to determine the microemulsion area. The total area of the microemulsion of different types for AEO9, n-alcohol, n hydrocarbon and water reached a maximum value when NO, carbon number of the oil, NO, carbon number plus that of the alcohol, NA, was equal to that of the AEO9, NS(NS= NO+ NA). The results are discussed theoretically.
    Volumetric Properties of Formamide, Acetamide and Urea in Two Kinds of Polar Non aqueous Solvents
    BAI Tong-Chun, YAO Jia, HAN Shi-Jun
    1999, 20(5):  777-781. 
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    Densities of solutions containing formamide, acetamide and urea in non aqueous polar solvents of N,N-dimethylformamide(DMF)and dimethylsulfoxide(DMSO), and solutions containing DMF and DMSO in formamide solvents were measured at 298.15 K. The apparent molar volume of solutes( V2φ) and the volumetric second virial coefficients( v22) were evaluated. The cavity volumes of solute in solvents and the interaction volumes were calculated by using scaled particle theory. Anegative effect of solute solvent interaction on v22was observed.
    Comparative Investigation of the Structure and IR of Tetrazolate Ion with Density Functional Theory and MP2 Ab initio Methods
    CHEN Zhao-Xu, XIAO He-Ming
    1999, 20(5):  782-787. 
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    Anumber of DFTmethods were used to calculate the geometry, electronic structure, IRand thermodynamic properties of tetrazolate ion. Comparisons were made between the DFT computed results and the MP2 ab initio ones. Compared with the ab initio results, it was found that the hybrid DFT method: B3LYP, has the best performance in calculating all these properties than the other DFT methods. Therefore, it can be used for systematic investigation of tetrazole derivatives and their complexes.
    Theoretical Studies of Various Possible Structures of CnSi( n =49,50)
    GE Mao-Fa, FENG Ji-Kang, CUI Meng, WANG Su-Fan, TIAN Wei-Quan, SUN Chia-Chung
    1999, 20(5):  788-793. 
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    The possible structures of CnSi( n =49, 50) are studied by using quantum chemistry ab initio method. Our studies show that C49Si has a closed cage structure with the silicon atom networked into the fullerene cage, and C49Si has a lower stability and higher chemical activity than the C50fullerene. There are two kinds of structures for C50Si, namely, Ⅰ exohedral and Ⅱ hole defect(the silicon atom connects to four carbon atoms). The calculated results show that, for C50Si, the exohedral complexes are more stable, i. e ., complexes Ⅰ are the main ingredient. The calculated results are in agreement with those of experimental observations.
    Selective One Step Synthesis of Acetic Acid from Syngas over Rh/NaY Catalyst
    XU Bo-Qing, Sachtler W. M. H.
    1999, 20(5):  794-796. 
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    Rhodium catalyst entrapped in the supercages of NaYzeolite(Rh/NaY) was used for syngas conversion at 1.0MPa and 250 ℃. It was shown that the catalyst was highly stable and selective for a direct synthesis of acetic acid. The selectivity of acetic acid was about 50% with a syngas that contains equal moles of CO and H2The selectivity increases up to 70% when n(CO)/n(H2)=3. No formation of ethanol was detected under steady catalysis, and the formation of all other C2oxygenates was below 5%.
    The Quantum Scattering Study for Ion pair Formation Reaction with LCAC-SW Method
    MA Wan-Yong, CAI Zheng-Ting, FENG Da-Cheng, DENG Cong-Hao
    1999, 20(5):  797-799. 
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    LCAC-SW method has been extended to study the reaction dynamics for ion pair formation processes. M+X2→M++X2-reaction system involves two potential energy surfaces, i. e., the covalence state(M++X2-) and the ionic state(M++X2-) and their crossing effect. The working equations for calculating state to state probability have been derived based on the above two state model. The selected state reaction probabilities of collinear ion pair formation process M+I2→M++I2-(M=Na, K, Cs) on Aten Lanting Los two state potential energy surface have been calculated. The results show that the reaction probabilities are of resonance effect.
    Electrochemical Studies of the Alkanethiols Film Adsorbed on Gold in the Solution of K3Fe(CN)6/K4Fe(CN)6
    CUI Xiao-Li, JIANG Dian-Lu, LI Jun-Xin, DIAO Peng, TONG Ru-Ting, WANG Xin-Kui
    1999, 20(5):  800-802. 
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    The self assembled monolayers(SAMs) of octadecanethiol and dodecylthiol are prepared. Its electrochemical behaviors in the solution of Fe(CN)63-/Fe(CN)64-with various concentrations are investigated by electrochemical impedance spectroscopy and cyclic voltammetry technology. Although there are no diffusion behavior in CV and EIS results, comparing with the theoretical results, it can be induced that there may be some collapsed or loosely packed sites (defects) in monolayers which provide a mechanism for rapid electron transfer.
    Synthesis and Properties of Optically Active Poly(amide-imide)s Containing Axially Dissymmetric 1,1′-Binaphthyl Moieties
    SONG Nai-Heng, GAO Lian-Xun, DING Meng-Xian
    1999, 20(5):  803-808. 
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    Novel optically active aromatic poly(amide imide)s(PAIs) containing 1,1′-binaphthyl 2,2′-diylunits in the main chain were prepared by polycondensation reactions of newly synthesized dianhydride, 2,2′-bis(3,4 dicarboxylzenzamido) 1,1′-binaphthyl dianhydride[(S)-BNDADA and (±)-BNDADA], with diamines. The properties of the resulted PAIs were fully characterized by a combination of investigations on inherent viscosity, thermal properties(DSC and TGA), specific rotation, CD and UV Vis absorbance. These PAIs showed good solubilities, thermal properties and optical stabilities. Interesting UV Vis absorption behavior of films casted from these PAIs was observed and analyzed.
    Morphological Evolution with Phase Inversion Process in Emulsifying Epoxy Resin
    YANG Zhen-Zhong, ZHAO De-Lu, XU Yuan-Ze, XU Mao
    1999, 20(5):  809-813. 
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    The morphological evolution with phase inversion process in emulsifying bisphenol Aepoxy resin was observed by SEM. It is revealed that the phase inversion process is completely achieved at the phase inversion point(PIP) when the concentration of the emulsifier is high, and a kind of sub micro waterborne particles of narrow size distribution is prepared. When the concentration of the emulsifier is low, the phase inversion process is incompletely achieved at PIP, and a kind of porous complex big waterborne particles of wide size distribution is obtained. In the former case, the interfacial layer of W/O structure is strong enough to impede the coalescence among water droplets before PIP. When the content of water reaches a critical value, the attraction between water droplets exceeds the repulsion, the nearest water droplets coalesce simultaneously to be continuous phase, which causes the complete phase inversion. In the latter case, the coalescence among the water droplets is noticeable due to the weak interfacial layer of W/O structure. Thus, the water droplets become larger after the coalescence and randomly dispersed in the continuous phase. The larger water drops coalesce furtherly to be continuous phase promoted by strong shear field and the W/O/W structure is formed. This is the feature of incomplete phase inversion.
    Synthesis and In vitro Blood compatibility of Polyurethane Graft Stearyl Poly(ethylene oxide)
    JI Jian, JI Ren-Tian, QIU Yong-Xing, CHEN Bao-Lin, FENG Lin-Xian
    1999, 20(5):  814-818. 
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    Anew grafted polyether, poly(tetramethylene glycol)-graft-ω-stearyl-poly(ethylene glycol)(PTMG-g-PEG-C18), was synthesized by the cationic polymerization of α-ω-bifunctional PEG macromonomer and THF. Polyurethane-graft-ω-stearyl poly(ethylene glycol)(PEU-g-PEO-C18), the new polyether as a soft segment, was synthesized. The results of platelet adhesion on PEU-g-PEG-C18surface indicated that the polyurethane can resist platelet adhesion on the original surface and pre adsorption albu min surface.
    Microscopic Kinetic Interpretation for "Cage Effect" of Initiator
    HUANG Qi-Shan, WENG Zhi-Xue, HUANG Zhi-Ming, PAN Zu-Ren
    1999, 20(5):  819-823. 
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    Considering that the diffusion phenomena of primary radical, which leads to the "cage effect" of initiator, is an unsteady process, we proposed an interpretation for this phenomena microscopically based on the free volume theory. The effects of initiator and monomer on the initiator efficiency are considered, then the applied range of classic theory fitting was given.
    Preparation of Monolithic Silica Glass by an Ultra fast Sol gel Process
    WANG Ce, ZHANG Ya-Hong, DONG Lin, FU Li-Min, BAI Yu-Bai, LI Tie-Jin, LIU Zhi Hong, WEI Yan
    1999, 20(5):  824-826. 
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    An ultra-fast sol-gel process has been developed to get high content silica materials, in which, the solvent tetrahydrofuran(THF) for hydrolysis of precursor tetraethyl orthosilicate, was removed through solvent extraction to obtain bulk sol. The bulk sol can be molded in different shapes such as discoid, pellet, octagon, cylinder, and half sphere. They solidified and gelled in a very short time in the presence of lithium salt. Measurements show that the silica monoliths possess volume shrinkage of 52%, high silica content of 82.4% and transmittance of 70% in the UV/Vis region, and are crack-free indefinitely.
    Chloromethylation and Hydroxymethylation of SEBS
    SHEN Zhong, ZHANG Yan, XIE Jing-Wei, YANG Yi-Qing
    1999, 20(5):  827-829. 
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    Hydroxymethyl groups were introduced into hydrogenated poly(styrene-block-butadiene-block-styrene)(SEBS) via chemical modification of the PSblocks by a simple three step procedure, i.e. , chloromethylation via Friedel-Crafts reaction with stannic chloride(SnCl4) as catalyst in chloroform solution in the presence of trioxane and chlorotrimethylsilane, followed by esterification and hydrolysis by using phase transfer catalyst TBAB. 1H NMR, FTIR, SEC and elemental analysis were employed to characterize the products. The results show that the degree of functionalization could be controlled in the first step, and the convertions of chloromethyl to ester and ester to hydroxyl were complete. Meanwhile molecular weight distribution of the product was still narrow. Crosslinking could be avoided when the polymer concentration was kept lower than its overlap concentration.
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