Table of Content

24 December 2003, Volume 24 Issue 12

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Articles

Syntheses and Characterization of Two Iron Complexes with N-Picoloylhydrazide

WU Wen-Shi, LIU Shi-Xiong

2003, 24(12):  2137-2142. 

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Two iron complexes with N-acetylpicoloylhydrazide (Haphz) and N-phenylpicoloylhydrazide(Hphphz), [Fe₂(aphz)₂(μ-CH₃OH)₂Cl₂]·CH₃OH(1, C₁₉H₂₆Cl₂Fe₂N₆O₇, Mr= 633.06) and Fe(phphz)Cl₂(2, C₁₃H₁₀Cl₂FeN₃O₂, Mr=366.99), were synthesized. Complex 1 belongs to a triclinic system, space group P1, with cell parameters a=0.83359(6) nm, b=1.09990(9) nm, c=0.75054(7) nm, α=91.412(3)°, β=96.683(3)°, γ=107.997(6)°, V=0.64869(9)nm³, Z=1, Dc=1.621Mg/m³, F(000)₃₂₄, μ(Mo Kα)=1.374mm^-1, R=0.0318 and _wR=0.0864 for 2547 observed reflections, GOF=1.112. Complex 2 belongs to triclinic system, space group P1, a=0.69038(6) nm, b_0.94607(9) nm, c=1.18582(7) nm, α=89.383(5)°, β=81.515(2)°, γ=69.214(2)°, V=0.7155(1)nm³, Z=2, Dc=1.704 Mg/m³, F(000)=370, μ(Mo Kα)=1.433 mm^-1, R=0.0681 and _wR=0.1352 for 1720 observed reflections, GOF=1.056. The binuclear complex 1 has a crystallographic center. The two methanol oxygen atoms in complex 1 bridges two iron atoms, forming a Fe₂(μ-O)₂core with crystallographic centrosymmetry and Fe...Fe distance is 0.31609 nm. The iron atom is octahedrally coordinated by two nitrogen atoms and one oxygen of the N-acetylpicoloylhydrazide ligand, two methanol oxygen atoms and one chloride ion. The neighboring molecules in complex 1 are connected by hydrogen bonding, forming an infinite chain structure. The iron(Ⅲ) ion in complex 2 has a strongly distorted square pyramidal geometry with three donors of the N-phenylpicoloylhydrazide ligand and two chloride ions. The two centrosymmetry-related molecules of complex 2 are connected as a pair by two N-H...Ohydrogen bonds. In the two title complexes, ν(C=O) and ν(C-N) are shifted to lower frequencies in IRspectra; π-π^*charge transitions and d-π^*charge-transitions are observed in their electronic spectra. The emission lines (λ_ex=310 nm) are shifted to higher frequencies in fluorescence spectra.

Preparation of Au Nanowires by a Liquid Crystal Template

ZHANG Dong-Bai, QI Li-Min, CHENG Hu-Min, MA Ji-Ming

2003, 24(12):  2143-2146. 

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Au nanowires were synthesized in lamellar liquid crystals of C₁₂E₄by using aqueous HAuC_l4solution as the aqueous phase of the liquid crystals and the C₁₂E₄itself as reducing agent. The effects of the reactant concentration, the surfactant/water molar ratio in the liquid crystal system and the reaction time on the morphology and size of the Au particles were investigated. The prepared Au nanoparticles are regular nanowires with a width of about 20 nm and a length of about several microns, showing a large aspect ratio under proper conditions. Alamellar liquid crystal templating mechanism has been proposed to interpret the experimental results.

Controlled Synthesis of HgS Nanocrystals with Artificial Active Membrane as Template

LIU Jin-Ku, WU Qing-Sheng, DING Ya-Ping, WANG Bin

2003, 24(12):  2147-2150. 

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Polynanocrystals of HgSwere synthesized with artificial active membrane of collodion as the template. The results indicated that approximately spherical HgS particles about 33 nm, which has a cubic zinc-blende structure with a cell parameter a=0.58516 nm, could be formed at room temperature with 0.1 mol/L HgS and 0.1 mol/L Na₂S as the reactants. In addition, the tentative research for the reaction mechanism has been carried out.

Synthesis of Co₃O₄Nanopowder with Different Morphologies by Hydrothermal Treatment Followed by Decomposition

ZHANG Wei-Min, SUN Si-Xiu, YU Hai-Yun, SONG Xin-Yu

2003, 24(12):  2151-2154. 

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The powder of Co₃O₄with a cubic structure and well-developed hexagonal platelets were synthesized hydrothermally, followed by decomposition of the precursors in the Co(NO₃)₂-NH₃or KOH system. The results of XRD and TEM which were used to monitor the processes of hydrothermal treatment and calcination showed that NO₃^-played a key role in the formation of Co₃O₄with different morphologies. Co₃O₄with a cubic structure could be directly prepared hydrothermally from the system with NO₃^-. After the NO₃^-was rinsed from the system, a topotactic phenomena was observed. Well-developed hexagonal platelets of β-Co(OH)₂were obtained from the hydrothermal system, and then, being baked at 300 ℃ in air, β-Co(OH)₂was transformed into Co₃O₄with the same morphology as the precursor.

Preparation of Ternary Metals Disulfide Nanotube

LI Guo-Hua, XU Zhu-De, CHEN Wei-Xiang, NIE Qiu-Lin, XIA Jun-Bao

2003, 24(12):  2155-2157. 

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Ternary metals disulfide nano-compound, Mn_x(MoW)_1-xS₂, was prepared by exfoliating-restacking-structure controlling approach, and characterized by XRD, TEM, SAED and EDS respectively. XRDresults show that the phases of the intermediate were composed of MoS₂, WS₂, MnCl₂·H₂O and one unclear phase. The end product was composed of MnS₂, MoS₂and WS₂phases. TEM results show that the morphologies of the sample are nano-tubular with ringent. EDS results show that the components of nanotube is Mn_x(MoW)₁-xS_2.More detailed work is needed to study the precise structure and formation mechanism for sure.

Synthesis and Characterization of CoW₁₁Ti/Starch Nanomaterials

WANG Xiao-Hong, WANG Li-Min, LI Feng, LIU Jing-Fu

2003, 24(12):  2158-2160. 

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Using a reversed-phase microemulsion polymerization method, polyoxometalates(POMs) CoW₁₁Ti loaded starch nanoparticles were prepared and structurally characterized by elemental analyses, IR, UV-Vis and ESRspectroscopy. The particle size of CoW₁₁Ti/starch was estimated by transmission electron microscope(TEM) and the size ranges by a 1000HSA MALVIRN Zetasizer instrument. The result shows that the polyoxometalate retained the parent structure after encapsulated by starch microspheres, which are able to enhance the stability and antitumoral activity of POMs and decrease the toxicity of POMs as well.

Measurement of Cardiac Troponin I by Sandwich Immunobiosensor Prepared with the Polyclonal Antibody

WEI Jing-Yan, MU Ying, XU Hai-Bo, HU Xin, SONG Da-Qian, LIU Xia, ZHANG Han-Qi, JIN Qin-Han, LUO Gui-Min

2003, 24(12):  2161-2164. 

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Cardiac and skeletal muscle troponin I(cTnI, sTnI) were purified from human left ventricular tissue and skeletal muscle tissue by affinity chromatographic method, respectively. The specific polyclonal antibody to cTnIwas prepared by immuned pure New Zeal and rabbit with the purified cTnIand purified by nitrocellulose membrance filtration-affinity chromatography with sTnI. Aspecific immunobiosensor for cTnIwas developed by using surface plasmon resonance(SPR) biosensor with biotin as an intermediate layer and with the biotinylated-specific polyclonal antibody as capture antibody and used in a direct detection of cTnIin sera with the lowest detection limit of 2.5 μg/L. Amore sensitive sandwich immunobiosensor for cTnIwas developed by using biotinylated-specific polyclonal antibody as capture antibody(the first antibody) and polyclonal antibody as the second antibody. The sandwich immunoassay showed an excellent sensitivity of 0.5μg/Land the detection range of 0.5-20 μg/Land within-run variation of 3.5%-4.9% and between-run variation of 6.1%-7.4%. The cTnI′s in the sera of 40 healthy donors and 20 patients with acute myocardiaLInfarction(AMI) were monitored by using the sandwich immunoassay and the Lifesign MI Troponin Itest device, respectively and it was found that the coincidence of the two assays was 95%, indicating that the developed sandwich immunoassay with SPRbiosensor is suitable in clinical determination.

Separation of N-(2-Ethyl-6-methylphenyl)alanine Enantiomers by Capillary Electrophoresis

ZHENG Liang-Yu, ZHANG Suo-Qin, GAO Gui, CAO Shu-Gui, ZHANG Gui-Rong, WANG Zhi, HAN Si-Ping, QUAN Jing

2003, 24(12):  2165-2168. 

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Capillary electrophoresis was used for the chiral separation of N-(2-ethyl-6-methylphenyl)alanine enantiomers in this paper. Capillary zone electrophoresis conditions were used with β-cyclodextrin or its derivatives as a chiral mobile phase additive. The effects of cyclodextrin type, variation of cyclodextrin concentration, background electrolyte pH, temperature and field strength were investigated. Optimum separation was achieved for N-(2-ethyl-6-methylphenyl)alanine enantiomers by using 2,6-di-O-methyl-β-cyclodextrin(40 mmol/L), the temperature(20 ℃) and pH(5.5). The mass concentration range from 20 to 200 mg/Lproved to be sufficient for exact quantification. The detection limitation is 10 mg/L. Anew method of using capillary electrophoresis for the chiral separation of N-(2-ethyl-6-methylphenyl)alanine enantiomers has been established.

Research on the Stability of Relative Strength of Sub-ion in ESI-MS-MS Analysis

SUN Ping, LUO Guo-An, QU Jun

2003, 24(12):  2169-2172. 

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The work presents an electrospray tandem mass spectrometric(ESI-MS-MS) method capable of validating the stability of the product ion ratios of alkaloids at the optimal collision energy(OCE). The mass spectrometer was operated in MS-MSmultiple reaction monitoring(MRM) mode, monitoring four reactions of one alkaloid. The product ion ratios are specific and reproducible(relative standard deviation: <6%, the percent deviation between two different matrixes: <4.5%). This unreported result shows the ion ratios at OCE are stable and independent of the analyte concentration and matrix. This described method can be used in the qualitative analysis in the complex matrix.

The Difference of FTIR Spectroscopic Studies on Normal and Malignant Tissues of Lung

ZHANG Li, WANG Jian-Sheng, YANG Zhan-Lan, XU Yi-Zhuang, WENG Shi-Fu, SHI Jing-Sen, WU Jin-Guang

2003, 24(12):  2173-2176. 

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Fourier transform infrared spectroscopy(FTIR) was applied to study the malignant and normal tissues of lung. The distinct differences were observed in the FTIR spectra between the normal and malignant lung tissues. Amide Ⅱ bands were weak in malignant tissues but strong in normal tissues; CHbending bands of malignant tissues around 1460cm^-1became lower than those of normal tissues; the bands around 1240 and 1080 cm^-1, related to P-Oand C-O stretching, respectively, both revealed different changes in malignant and normal tissues. The results also show that four groups of relative intensity ratios, including I₁₆₄₀/I₁₅₅₀, I₁₄₆₀/I₁₄₀₀, I₁₂₄₀/I₁₃₁₀and I₁₀₈₀/I₁₁₆₀, were used to distinguish the normal and malignant tissues. The relative intensities of I₁₆₄₀/I₁₅₅₀and I₁₀₈₀/I ₁₁₆₀of the malignant tissues were higher than that of the normal tissues; nevertheless those ratios of I₁₄₆₀/I₁₄₀₀, I₁₂₄₀/I₁₃₁₀were lower in the malignant tissues. This might indicate that the FTIRspectroscopy can be used in the clinical diagnoses.

Surface-enhanced Raman Spectroscopy of the Coupling Molecules in Self-assemblies of Silver Nanoparticles

ZHOU Yao-Guo, ZHENG Jun-Wei, LI Xiao-Wei, JI Yuan, GU Ren-Ao

2003, 24(12):  2177-2180. 

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Ordered mono^-and double-layer structures of silver nanoparticles on smooth silver substrates were fabricated by self-assembly technique, where 1,4-benzenedithiol and p-aminothiophenol were used as the coupling molecules, respectively. The results of surface-enhanced Raman spectroscopic characterization shows that Raman scattering of the coupling molecules in the self-assemblies is greatly enhanced. The results demonstrate that the enhancement of 1,4-benzenedithiol results from the electromagnetic coupling of the smooth silver substrate with the mono-layer of silver nanoparticles, whereas the enhancement for p-aminothiophenol arises from the coupling interaction of two layers of silver nanoparticles. The enhancement effects in both cases are comparable to each other.

Identifying the Authenticity of Chinese Medicinal Material with Chemical Fingerprint Features

CHEN Min-Jun, QU Hai-Bin, CHENG Yi-Yu

2003, 24(12):  2181-2185. 

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Amethod for identifying the authenticity of Chinese Medicinal Material(CMM), using Fisher factor(FF) as chemical fingerprint features, is proposed. According to the principle of maximizing the distance among classes and minimizing the distance within classes, the weights of different peaks in chromatograms are calculated, and then a transformation vector is composed by these weights. FF can be obtained by multiplying the transformation vector with the vector composed of the area values of every peak selected based on user's threshold. As a typical example, identifying the authenticity of the main root of red ginseng was used to verify the effectivity of the proposed method. Comparing FFs with principal components and chromatographic peaks from three aspects of the quantitative evaluation, visual analysis and cluster analysis, it is shown that FFhas the highest accuracy in identifying the authenticity of the main root of red ginseng. Therefore, as a chemical fingerprint feature, FFcan be used to identify the authenticity of CMM.

Detection-visualized Genechips For HBV

LI Wei, PANG Dai-Wen, WANG Ye-Fu, YAN Qin, ZHANG Zhi-Ling

2003, 24(12):  2186-2188. 

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Visual method based on nanogold-supported probes was optimized and used to detect HBV extracted from positive serum samples, which was compared with fluorescence method based on FITC-labeled probes. The resultant detection-visualized genochips have special advantages, such as simple operation and low cost etc.. So such genochips will be hopefully used for virus detection.

Studies on Droplet Optical Chemistry Sensor of Thiamine Based on It′s Oxidation by Mercury Ion

FENG Feng, WANG Ke-Min, YANG Rong-Hua, ZHOU Lei-Ji, HUANG Hong-Mei, HUANG Shan-Sheng, LI Du

2003, 24(12):  2189-2191. 

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Anovel renewable liquid drop sensor was proposed for quantitative assay of thiamine based on it′s oxidation by Hg²⁺in basic medium. The dynamically growing and falling drops formed at the end of a silanized silica capillary tube served as the reactors for a chromogenic reaction and windowless optical cells as well. The optimum analytical conditions have been established. The sensor showed a linear response in the measuring range from 1.0×10^-4to 5.0×10^-3mg/mLthiamine, and with a detection limit of 8.0×10^-4mg/mL. Besides its high sensitivity, the sensor permits a simple, fast, and inexpensive measurement with only micro-quantities reagent consumption.

Preparation and Characterization of Zirconia Nanoparticle Multilayers on Micrometer-sized Silica Particle for HPLC Support

DUN Hui-Juan, SONG Xiu-Qin, WEI Yu, LI Yong-Min, CHEN Li-Ren

2003, 24(12):  2192-2194. 

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The uniform zirconia nanoparticle multilayers/micrometer-sized silica particle(ZrO₂/SiO₂) was prepared for HPLC support material by layer-by-layer(LbL)self-assembly technique. XRD pattern shows that the crystalline of nanometer particles on the surface is pure tetragonal zirconia, with a diameter of 13.9 nm. The specific surface area, pore volume and pore size of the material are 172.53m²/g, 0.3784cm³/g, and 8.5 nm, respectively. The novel support not only has the mechanical strength and chemical stability of zirconia, but also has the good chromatographic features such as larger surface area, better permeability, less background pressure.

Synthesis, Characterization and Substitution Effect on Mesogenic Properties of Ferrocene-containing Liquid Crystal Without Soft End Group

HU Ping, ZHAO Ke-Qing, XU Hong-Bo, ZHANG Liang-Fu

2003, 24(12):  2195-2201. 

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Seventeen ferrocene-containing compounds with four phenyl rings and ester, imine group as the central bridge were synthesized. The structures were characterized by IR, NMR and elemental analysis. The mesogenic properties were studied by DSC and polarized optical microscopy. The effect of substituents on the mesogenic behavior was discussed. The results show that most of these compounds have a liquid crystal phase.

Comparative Proteome Analysis of Human Brain Occipital Lobes During the Course of Aging

ZHOU Bo, YANG Wei, ZHANG Jing-Hua, TONG Yuan-Peng, ZHAO Rui, JI Jian-Guo+, RU Bing-Gen

2003, 24(12):  2202-2207. 

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Proteomic analysis is a powerful tool to reveal the mechanisMOf functional changes of central nervous system and the origination, development and prognosis of central nervous disease. Human brain proteins were isolated from human occipital lobes at five ages from 23 to 94 years old, and separated by two dimensional gel electrophoresis. Over one thousand protein spots were resolved in one gel with commassie brilliant blue staining. Differential expression of proteins with increasing ages was analyzed by Image Master 2D Elite software processing. Seven protein spots were found to increase or decrease with increasing ages consistently. Taking advantage of the high sensitivity and accuracy of mass spectrometry, 11 proteins with significant changes were identified by peptide fingerprinting map(PMF) or peptide sequence tag(PST) obtained from MS or tandem MS(MS/MS). Among the identified proteins, the amount of 5 proteins were increased or decreased consistently, including neurofilament triplet Lprotein(NF-L), a protein involved in the maintenance of neuronal caliber; peroxiredoxin(EC 1.11.1.), an antioxidant enzyme; aconitate hydratase(EC 4.2.1.3), a key enzyme in tricarboxylic acid(TCA) cycle; enolase 2(EC 4.2.1.11), a key enzyme in glycolysis pathway; T-complex protein 1, a chaperone. In summary, the two dimensional map of human brain occipital lobe proteins was firstly established, significantly changed proteins during the course of aging were identified and their possible biological significance was discussed.

Synthesis and iNOS Inhibitory Activity of S-Alkyl(or aralkyl)-1-alkyl (or aryl)-3-[4-(benzimidazole-2-mercapto)phenyl] Isothioureas

XU Yun-Gen, HUA Wei-Yi, ZHU Dong-Ya, SHI Yu, FENG Xiao-Qin

2003, 24(12):  2208-2214. 

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In order to get some novel potent compounds with iNOS inhibitory activity for the treatment of septic shock and inflammation, 20 target compounds of S-alkyl(or aralkyl)-N-[4-(benzimidazole-2-mercapto) phenyl] isothioureas(6a-6j) and S-alkyl(or aralkyl)-1-alkyl(or aryl)-3-[4-(benzimidazole-2-mercapto) phenyl] isothioureas(8a-8j) were synthesized by two different synthetic methods from 2-mercaptobenzimidazole(1). Compounds 6a-6j were synthesized from 2-(4-aminophenylmercapto) benzimidazole(3) by reaction with benzoyLIsothiocyanate to form the corresponding benzoylthioureas 4 which was hydrolyzed with 2.0 mol/Lsodium hydroxide solution containing tetrahydrofuran, followed by S-alkylation with alkyLIodide or (substituted) benzyl halogen. Compounds 8a-8j were synthesized from compound 3 by reaction with alkyl(or aryl) isothiocyanate to form the corresponding 1,3-disubstituted thioureas 7 which was S-alkylated with alkyLIodide or (substituted) benzyl halogen. The intermediate 3 was synthesized from 2-mercaptobenzimidazole(1) by reaction with 1-chloro-4-nitrobenzene to form 2-(4-nitrophenylmercapto)benzimidazole(2) which was reduced by iron powder and hydrochloric acid. The structures of these compounds were confirmed by IR, MS, ¹HNMR and elemental analysis. The results of preliminary pharmacological test show that most of these compounds possess iNOS inhibitory activity, among which compounds 6b, 8d and 8f have a comparable activity to the control aminoguanidine.

Isolation and Structure Identification of the Novel Alkaloid Constituent from Epimedium Koreanum Naki

LIU Chun-Ming, LIU Zhi-Qiang, DOU Jian-Peng, LI Li, LIU Shu-Ying

2003, 24(12):  2215-2217. 

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Anovel kind of alkaloid was isolated from the aerial of Epimedium koreanum Naki. The molecular weight and molecular formula were achieved by FT-ICRMS as 370.1285012 and C₂₀H₂₀O₆N. The molecular structure of the compound C₂₀H₂₀O₆N was determined on the basis of spectral analyses as 6-hydroxy-11,12-dimethoxy-2,2-dimethyl-1,8-dioxo-1,3,4,8-tetrahydro-2H-7-oxa-2-azonia-benzo phenanthene. Using electrospray ionization multi-stage mass spectrometry, the structure was confirmed further. The compound was first reported from this kind of plant.

Preparation of dl-Dibenzophenanthrene by Using Benzyl-type Binaphthyl Disulfone

AN De-Lie, TAN Xiao-Hua, PENG Zhi-Hong, SHAO Guang

2003, 24(12):  2218-2220. 

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We reported that a benzyl-type binaphthyl disulfone could be conveniently converted into dibenzophenanthrene. Thus, racemic 1 was treated with lithium diisopropylamide (LDA) afforded dl-dibenzophenanthrene in a moderate yield, together with an unknown benzensulfonyl-substituted derivative 2. The structures were confirmed by MS, ¹H, ¹³CNMR and elemental analysis. The reaction might involve the initiaLIntramolecular nucleophilic substitution to produce an intermediate 3, followed by elimination of benzenesulfinic acid to form dibenzophenanthrene.

Relationships Between Structure and Activity for Flavonoids to Lipid Peroxidation in Liver Microsomer from Rat

JIANG Hui-Di, FANG Wei-Jie, FU Xu-Chun, LIU Feng-Lan, HU Yong-Zhou

2003, 24(12):  2221-2223. 

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IC₅₀values of 13 flavonoids to lipid peroxidation induced by OH^·in liver microsomer from rat were evaluated and the relationship between structure and activity was studied. The flavonoids with catechol group, which usually have a higher energy in the highest occupied molecular orbital and lower ΔHOF values, have higher inhibitory activities than those without catechol group. The flavonoids without catechol group in Bring not being suitable structure to chelate with Fe²⁺have little inhibitory activities. The results suggest the anti-lipid peroxidation activity of flavonoids is related with the structure of flavonoids.

On the Theoretical Study of the Potential Energy Surface for the C₂H+NO₂Reaction

WEI Zhi-Gang, HUANG Xu-Ri, SUN Yan-Bo, SUN Chia-Chung

2003, 24(12):  2224-2226. 

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Asinglet potential energy surface for the reaction of C₂H radical with molecular NO₂is studied at the CCSD(T)/6-311G(d,p)//B3LYP/6-311G(d,p)+ZPE level to give three products P1(HCCO+NO), P2(HCNO+CO) and P3(HCN+CO₂). The RRKM calculations are performed to estimate the total and individual rate constants. It is shown that the total rate for the reaction C₂H+NO₂can be expressed as 1.427×10^-12×T^0.556×exp(190.547/T) cm·molecule·s^-1, and the major products P1 is more than 96% and the minor products P2 and P3 are less than 4%.

A Valence Bond Method Study for S_N2 Reaction X_l^-+CH₃X_r→X_lCH₃+X_l^-(X_l=X_r=F,Cl,Br,I)

CHEN Yan-Fen, SONG Ling-Chun, WU Wei, ZHANG Qian-Er

2003, 24(12):  2227-2230. 

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Barriers and VBquantities for S_N2 reaction X_l^-+CH₃Xr→XlCH³⁺X_r^-(X_l=X_r=F, Cl, Br, I) are calculated by valence bond configuration interaction(VBCI) method. The computational results show that the VB results obtained by using CImethod are in good agreement with those obtained by using the molecular orbital based coupled cluster CCSD method. The reaction parameters for the S _N2 identity reaction, including promotion gap G, height of crossing point, resonance energy B, and curvature factor f, are discussed. They show the same trend as that predicted by semiempirical VBtheory, and provide quantitative data for understanding the reaction mechanism.

DFT Studies on Electronic Spectra and Nonlinear Optical Properties of Symmetric Squaraine Derivatives Linked with Borazine

YUE Shu-Mei, TAN Ke, ZHANG Min, LAN Ya-Qian, SU Zhong-Min

2003, 24(12):  2231-2234. 

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The geometrical structures of symmetric 2,4-squaraine compounds have been optimized by using DFT-B3LYP/6-31G(d). On the basis of them, electronic absorption spectra of the compounds were investigated with TD-DFT and second-order hyperpolarizability γ were calculated by means of finite field (FF) method by introducing an external electronic filed. It is shown from the calculation that the borazine is a donor, different from benzene. Charge population, FMO and NLO properties change distinctly with change of the the atom linked to squaraine. To increase the γ value of a donor group, the atom linked to other group must be Natom. The best value of γ in the symmetric squaraine derivatives linked with borazine can reach 2.3808×10^-24C·m.

Catalytic Activity of Fe₂O₃/YSZ-γ-Al₂O₃for Methane Combustion

LI Li-Na, CHEN Yao-Qiang, GONG Mao-Chu, XIANG Yun

2003, 24(12):  2235-2238. 

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Catalysts for methane combustion were prepared by Fe₂O₃supported on γ-Al 2O₃, ZrO₂-γ-Al₂O₃, YSZ(Yttria stabilize Zirconia)-γ-Al₂O₃, respectively. Among the three kinds of catalysts, Fe₂O₃/YSZ-γ-Al₂O₃show the highest activity and best thermal stability. XPS result demonstrates that the addition of ZrO₂and Y₂O₃can increase and stabilize the surface concentration of Fe₂O₃and decrease the interaction between iron species and γ-Al₂O₃support. Fe₂O₃/YSZ-γ-Al₂O₃catalyst with a mass fraction of Fe₂O₃10% has the highest catalytic activity. XRD result indicate that the catalytic activity is related to the state of Fe₂O₃dispersion on the support.

Synthesis of Conductive Polyaniline in AEOT/iso-Octane/Water Reversed Micelle System

LIU Cheng-Zhan, CHU Ying, XING Shuang-Xi, SUI Xiao-Meng, WU Zi-Sheng

2003, 24(12):  2239-2242. 

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Conductive polyanilne with small and uniform size was prepared by using reversed micelle formed from self-made anion surfactant called sodium bis sulfosuccinate(AEOT) as the template. The effects of polymerization conditions including reaction time, reaction temperature, molar ratio of oxidant to aniline, concentration of the acid, dosage of the surfactant and recycle use of the surfactant on the properties of the product were discussed. The characterizations of the product were measured by IRspectra, UV-Vis spectra, X-ray diffraction, Olympus microscope and TEM.

Studies on Interfacial Dilational Visoelasticity of Active Constituents in Crude Oil with Different Molecular Weights by Interfacial Tension Relaxation Methods

SUN Tao-Lei, ZHANG Lu, WANG Yi-Yang, ZHAO Sui, YU Jia-Yong

2003, 24(12):  2243-2247. 

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The dilational viscoelasticity behavior on oil-water interfaces formed by surface active constituents with different average molecular weights and atom ratios of H to C, which were distilled by supercritical fluid extraction and fractionation(SFEF) method from Iranian heavy oil, were investigated. The interfacial relaxation processes were investigated by interfacial tension relaxation method. The dependencies of dilational elasticities and viscosities on dilational frequency were expounded. It is shown that when the dilational frequency was lower, dilational elasticities of the constituents was about zero; dilational elasticities increased when the dilational frequency became bigger at a medial frequency; and when the dilational frequency was higher, the dilational elasticities was close to its limiting value. It is also shown that the dilational viscosities showed a maximum value with the change of frequency. The dilational elasticities increased along with the increase of number average molecular weights and decrease of atom ratios of Hto Cin the samples. With the increase of average molecular weights and decrease of atom ratios of Hto Cin the samples, slow relaxation processes gradually appeared and the contribution of them increased, the characteristic time of similar processes of different samples also increased. The results illustrate that the constituents containing large condensed ring aromatic compounds that have large conjugated structure played a more important role in film-forming and film rigidity than the constituents of small molecule.

Physio-chemical Properties of Adsorbing Pd²⁺by Saccharomyces Cerevisiae Waste Biomass

LIU Yue-Ying, DU Tian-Sheng, CHEN Ping, TANG Ding-Liang, NI Zi-Mian, GU Ping-Ying, FU Jin-Kun

2003, 24(12):  2248-2251. 

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Saccharomyces cerevisiae waste biomass procured from the beer brewery, was used as the adsorbent for Pd²⁺. The physico-chemical properties of adsorbing Pd²⁺by the biomass were investigated. The results indicate that the adsorption of Pd²⁺by the biomass was affected by adsorption time, pHvalue, adsorbent concentration and Pd²⁺initial concentration in the solution. The biosorption is a rapid process, the capacity of the adsorption after 45 min reached the maximum, and 92.0% of the maximal capacity was obtained at the first 3 min of the adsorption. The optimum pH value was 3.5. In the range of 5-60 ℃, the biosorption was not affected by temperature. The isotherMOf the adsorption of Pd²⁺by the biomass followed Langmuir and Freundich models under the conditions of initial Pd²⁺mass concentration(30-300 mg/L) and biomass mass concentration(2g/L). Biosorptive capacity of 94.5 mg/g was obtained under the conditions of pH=3.5, mass ratio of an initial Pd²⁺to biomass being 0.2 and at 30 ℃ for 60 min of the adsorption. Palladium was removed from the treated solution of waste palladium catalyst with 32.2 mg/g of biosorptive capacity. The results of X-ray photoelectron spectrometer analysis indicate that the biomass could adsorb Pd²⁺ions from the aqueous solution. The observation in the transmission electron microscope shows that without the extra-electron donor, the waste biomass of Saccharomyces cerevisiae could adsorb and reduce Pd²⁺ions in the solution to microbial Pd⁰particles, which could become well-formed palladium crystals, as well as Pd²⁺ions adsorbed on the γ-Al₂O₃could be reduced to Pd⁰particles by the biomass.

Symmetrization of the Localized Fragment Molecular Orbital Basis

YU Zhong-Heng, XU Hong, MA Yan-Ping

2003, 24(12):  2252-2255. 

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The UHFcomputation for a fragment resulted from the breaking of the single bonds can′t ensure that each of the opened-shell delocalized FMO s (fragment molecular orbitals) Ψ_i^ohas a correct electronic occupancy. It is necessary to localize Ψ_i^owith the Kost method. However, the Kost localization destroys the symmetry of the localized FMO basis set Ψ iin the case of fragments such as -CHCH- and CH that are the fragments of polynorbornyl diene and resulted from the breaking of two and three carbon-carbon single bonds respectively. In this work, the localized FMO basis Ψ_ifor ethylenic group was taken as an example, the procedures for symmetrizing Ψ_iare detailed. At a higher Gaussian basis level such as 3-21G, the method that determines the length r of the bond between carbon atom and its one referential hydrogen HR is introduced.

Effect of Additive Elements on Electrochemical Properties of AB₂-type Laves Phase Alloys

HAN Shu-Min, ZHAO Min-Shou, WU Lai-Lei, ZHENG Yang-Zeng

2003, 24(12):  2256-2259. 

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For examining the effect of the additive elements on the AB₂-type Laves phase alloys Zr_0.9Ti_0.1Ni_0.1Mn_0.7V_0.3M_0.1(M=None, Ni, Mn, V, Co, Cr, Al, Fe, Mo, Si, C, Zn, Cu and B), the phase structure, the electrochemical capacity, high rate dischargeability, charge retention, cycling stability, high-temperature and low-temperature dischargeability of the alloys have been investigated. The XRD results show that all alloys consist of a large amount of the hexagonal C₁₄Laves phase along with a small level of the cubic C₁₅Laves phase and some non-Laves phases. The addition of Vand Mn increases the discharge capacity of the AB₂alloy electrodes and the high rate capacity, and low-temperature dischargeability is dramatically increased with Band Mn addition, the Zr_0.9Ti_0.1Ni_1.1Mn_0.7V_0.3B_0.1exhibited the discharge capacity of 200mAh/g at discharge current of 1320mA/g. It is found that a small amount ddition of Al, C, Si and Co greatly improved the cycle life, but addition of Mn, V, Ni, Fe, Cu, Mo and Bdecreased the cycling stability of the AB₂alloy electrodes to some extent, especially addition of Mn resulted in decreasing of cycling stability drastically. The addition of Si, Mo, V, Cr and ALIs useful to improving self-discharge characteristics. Considerable improvement in the high-temperature dischargeability was observed by addition of Si, Cr and V, the discharge capacity was up to 210 mAh/g at 65 ℃ for Zr_0.9Ti_0.1Ni_1.1Mn_0.7V_0.3Si_0.1alloy electrode.

Preparation of LiMn₂O₄as Cathode Materials of Lithium Ion Batteries and Its Electrochemical Properties

CHEN Bin, FU Qiang, HUANG Xiao-Wen, XIE Zhong-Wei, HE Xing-Quan, SUN Hai-Zhu, XIE De-Min

2003, 24(12):  2260-2262. 

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Lithium ion batteries were intensively used in the field of portable computer and communication. If one doubles the specific capacity of the positive electrode, e.g. by using an oxide that could reversibly intercalate 1 Li instead of 0.5 Li per 3d-metal, one could increase the specific capacity of the cell by 68%. In contrast, if one doubles the specific capacity of the negative electrode, one could increase the overall specific capacity of the cell by only 12%. Thus, to improve the specific capacity of lithium ion batteries, we should dedicate our effort to the synthesis of new positive electrode materials, i.e.. Vacious lithiated oxides that could reversibly intercalate one Li atom per 3d-metal atom at about 4 Vversus Li. LiMn₂O₄is a promising candidate for cathode because of its high voltage, low coat and nonpolluting for environment. Sol-gel method is used to synthesize the cathode materials recently. The material has a high first-discharge capacity and long cycle life, and the synthetic process is simple: it reacts at a low temperature and the sample particle is uniform in size.

Studies on Electrocatalytic Performance of TitaniuMOxide Electrode Modified with Pt Toward Oxidation of CO

LIU Jing-Hua, YU Chun-Bo, WANG Yu-Jiang, XING Wei, LU Tian-Hong, ZHOU Yong-qing

2003, 24(12):  2263-2267. 

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Electrocatalytic performance of the Pt-TiO_x/Ti electrode prepared with electrochemical reduction-oxidation method toward the oxidation of CO was studied. The effects of preparation conditions on the electrocatalytic oxidation of CO were also investigated. The experimental results show that the Pt-TiO_x/Ti electrode has a high electrocatalytic activity, which was manifested through the negative shift of the peak potentiaLIn the positive scanning of the cyclic voltammogram, and good stability for the electrocatalytic oxidation of CO. By means of XPS techniques, it is found that the Pt in the Pt-TiO_x/Ti electrode is in a state of metal and the Ti is in a state of TiO_x. The reason for the electrode to exhibit an excellent performance is attributed to the high dispersion between nanosized Pt and TiO_xparticles and the low adsorption ability of the CO on the electrode surface is due to the interaction between Pt and TiO_x.

Electrochemical Study of Microperoxidase-11 Immobilized on the Surface of a Poly-L-lysine Modified Gold Electrode

WAGN Feng-Bin, ZHENG Jun-Wei, LI Xiao-Wei, JI Yuan, GAO Ying, XING Wei, LU Tian-Hong

2003, 24(12):  2268-2270. 

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MP-11 was immobilized on the surface of the poly-L-lysine modified gold electrode. Direct electron transfer between the heme and the electrode was observed. The formal redox potential for MP-11 immobilized at the gold electrode is -0.39 Vin the phosphate buffer solution(pH=7.0). The MP-11 modified electrode possesses the good electrocatalytic activity for the reduction of O₂When imidazole becomes the sixth ligand, the formal redox potential of MP-11 would shift to the negative direction and the electrocatalytic activity of MP-11 for the reduction of O₂is significantly inhibited.

GNP Synthesis and Electrical Conduction Properties of La_0.6Sr_0.4Co_1-yFe_yO₃Perovskite-type Oxides

XU Qing, HUANG Duan-Ping, CHEN Wen, WANG Hao, YUAN Run-Zhang

2003, 24(12):  2271-2274. 

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La_0.6Sr_0.4Co_1-yFe_yO₃(y=0-1.0) fine powders were synthesized by a Glycine-Nitrate Process (GNP) method, and a perovskite-type structure with rhombohedral symmetry was certified for the powders by XRD. The electrical conductivity of La_0.6Sr_0.4CoO₃(y=0) decreased monotonously with the increase of temperature in the range from room temperature to 900℃, while the electrical conductivities of it in other n(Co)/n(Fe) ratios increased with increasting temperature and reached the maximums of 3.22×10²-1.5×10³S/cm near 600 ℃ and then decreased. The hopping of small polarons is the dominating mechanism for the electrical conduction at low temperatures. The activation energy of the small polarons hopping increased from 3.378 to 17.471 kJ/mol with the decrease of n(Co)/n(Fe) ratio. Compared with the La_0.6Sr_0.4Co_1-yFe_yO₃synthesized by a conventional solid state reaction method, those synthesized by the GNP method exhibit a higher sintering activity and electrical conductivities. The differences in the temperature of electrical conductivity maximum and activation energy between the La_0.6Sr_0.4Co_1-yFe_yO₃oxides with an identical composition synthesized by the GNP method and solid state synthesis method, respectively, are attributed to the influences of stoichiometry and microstructure on electrical transportation process.

Resonant Two-photon Ionization Spectra of van der Waals Complexes C₆H₄(CH₃₂:Ar, N₂, NH₃(ND₃)

HU Yi-Hua, CHEN Li, WU Huai-Xuan, WANG Xiao-Juan, LIU Mei-Xi, YANG Shi-He

2003, 24(12):  2275-2278. 

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Resonant two-photon ionization spectra of van der Waals complexes C₆H₄(CH₃)₂:Ar, N₂, NH₃were reported by using one-color resonant ionization technique, together with time-of-flight mass spectrometry, in supersonic molecular beam. All observed bands were rationally assigned by calculated levels, isotope effect, and spectral analysis. According to the spectra assignment, the frequencies of van der waals vibrations for these complexes were obtained.

3D Modeling of SARS Virus Proteinase and Study of Imaginable Peptide Inhibitor

GAO Xue-Feng, ZHAO Xi, HUANG Xu-Ri, SUN Chia-Chung

2003, 24(12):  2279-2281. 

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SARS is a positive-stranded virus featuring the largest viral RNA genomes today. The viral main proteinase(Hydrolase), controlling the activities of SARS virus replication, is an attractive target for therapy. We determined crystal structure for transmissible gastroenteritis virus(TGEV) hydrolase, and constructed a homology model for SARS coronavirus proteinase on Silicon Graphics station by Insight Ⅱ molecule simulation software. The structure may reveal remarkable degree of conservation of the substrate binding sites. We design an imaginable peptide precursor for inhibitor, and the base shape of pocket and property of the residues may be used as a basis for designing anti-SARS drugs.

Surface Photo-generated Charges Study of Nanometer TiO₂

LI Zi-Heng, WANG De-Jun, ZHANG Qing-Lin, YANG Qiu-Jing, XU Zi-Li, DU Yao-Guo

2003, 24(12):  2282-2284. 

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The photo-generated charge property of TiO₂nanoparticles annealed at different temperatures was studied by the field induced surface photovoltage spectrum (FISPS) technique. The powder of TiO₂was prepared and annealed at 400, 600 and 800 ℃, respectively. The crystalline of TiO₂transformed from anatase to rutile with the annealing temperature increasesing. And the photo-generated charges property of TiO₂behaves differently after it was annealed at different temperatures. When the powder was annealed at 400 ℃, the particle size is so small that the energy band can not be formed completely, so the bound exciton state was formed when it was illuminated by the proper incident light, and it inverse antisymmetrically under external field for locatization effect. While, the powder was annealed at 600 ℃, the surface phtovoltaic response presents the characteristics of homojunction for different crystalline interfaces. After being annealed at 800 ℃, the energy band was formed completely and the larger particle size(36nm) was got. Consequently, a band for the dissociation of free exciton emerged in the band edge of the surface photovotaic response distinguished from the band-band transition, and the direction of the photovoltaic response resulted from the free excition is consistent with the external field, that is positive under positive field, and it inverse symmetrically under external field.

Rapid Synthesis of Pt/Carbon Nanometer Catalyst by Microwave Irradiation and Its Electrocatalytic Activity for Electrooxidation of Methanol

CHEN Wei-Xiang, HAN Gui, LEE Jim-Yang, LIU Zhao-Lin

2003, 24(12):  2285-2287. 

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As a rapid uniform and efficient heating method, microwave irradiation has been widely used in chemical reaction and preparing nanomaterials. Here Pt/carbon nanotube(CNT) catalysts with w(Pt)=18.1% and 9.4 % were rapidly synthesized by microwave irradiation heating polyol process and employing the ethylene glycol solution of H₂PtCl₆as the precursors in the presence of CNT support. TEM imaging showed that microwave-prepared Pt nanoparticles were very uniform in size, with an average size of 3.1 nm, and uniformly dispersed on the CNT surface. Electrochemical experiments demonstrated that microwave-synthesized Pt/CNT catalysts exhibited a higher catalytic activity for electrooxidation of liquid methanol than E-TEK Pt/C. The significant improvement in catalyst performance derives from that microwave-synthesized Pt nanoparticles have a uniform small particle size and uniforml dispersion on the CNT surface.

Surface Photovoltaic Properties of TiO₂Nanoribbons

CAO Jian, SUN Jing-Zhi, HONG Jian, CHEN Hong-Zheng, WANG Mang

2003, 24(12):  2288-2289. 

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TiO₂nanoribbons were synthesized hydrothermally via the reaction of TiO₂particles and NaOH solution. Their photovoltaic properties were studied by surface photovoltage spectroscopy (SPS) and electric field-induced surface photovoltage spectroscopy (FISPS). Under the external field, new photovoltaic response bands were found from 375 nm to 550 nm. It is suggested that these response bands resulted from the surface states, which can be ascribed to the formation of steps and kinks in the TiO₂nanoribbons.

Electrical-magnetic Properties of Nanocomposites of Conducting Polyaniline and γ-Fe₂O₃Nanoparticles

YANG Qing-Lin, ZHAI Jin, SONG Yan-Lin, WAN Mei-Xiang, JIANG Lei, XU Wen-Guo, LI Qian-Shu

2003, 24(12):  2290-2292. 

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Nanocomposites of PAn-DBSA/γ-Fe₂O₃with electrical and ferromagnetic behavior(σ= 2.18×10^-3-5.00×10^-5S/cm, M_s=3.7-16.6m²·A/kg, H_c=8805.2-9133.1A/m) were prepared by a chemical modification-redoping method in a neutral medium. The products were characterized by TEM, XRD, UV-Vis, four-probe method, and magnetometer. The results indicate that the electrical and magnetic properties of the nanocomposites strongly depend on γ-Fe₂O₃content. With the increase of γ-Fe₂O₃content, the electrical conductivity is decreased and saturation magnetization is increased.

Studies on the Wettability of Molecular Deposition (MD) Films of Phthalocyanine Copper Cation and Anion on Quartz Substrate

GAO Mang-Lai, CHEN Gang, ZHANG Hua

2003, 24(12):  2293-2295. 

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The result of UV-Vis adsorbance indicates that phthalocyanine copper cation and anion monolayers are alternately deposited, and dimmer is the major form. Through analyzing the 20th phthalocyanine MD film AFM image, we know that the surface of MD film is flat and compact. The physical-chemical properties of molecular end-group have influence on the MD films surface character notably. The contact angles of water on the odd and even layer MD films vary greatly complying with "odd-even" regularity, and the value increases slightly with the increment of MD film layers due to the decrease of van der Waals force reinforced by substrate through MD films.

Effect of ZnCl₂Doping on the Structure and Properties of Carbonized Phenolic Resin Material

ZHOU De-Feng, ZHAO Yan-Ling, HAO Jie, MA Yue, ZHANG Xi-Yan, SU Zhong-Min, WANG Rong-Shun

2003, 24(12):  2296-2299. 

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The influence of ZnCl₂doping on the structure and properties of carbonized phenolic resin material was investigated in detail. The structure and electrochemical properties of the carbonaceous material were measured by means of XRD, SEM, BETand Raman analyses, respectively. The results show that after doping ZnCl₂, the crystallinic size and distance between layers become larger, the partical size also tends to be uniform, the apertures and specific surface area of the product tend to be uniform, the apertures and specific and specific surface area of the product are obviousely increased. Moreover, the product size and internal aperture are alLIn nano-level range. By using this carbonaceous product as the electrode material, the reversible discharge capacity of the battery can reach 745mA·h/g.

Crystal Morphology of Phenyl-capped Tetraaniline in the Leucoemeraldine Oxidation State

ZHOU Yun-Chun, GENG Jian-Xin, CHEN Jian-Feng, LI Gao, ZHOU En-Le, CHEN Liang, ZHANG Wan-Jin

2003, 24(12):  2300-2303. 

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Aseries of crystals of phenyl-capped tetraaniline in the leucoemeraldine oxidation state were obtained with three different preparation methods and were observed directly under transmission electron microscope(TEM). The crystals that crystallized at a higher temperature have a more perfect structure than those at a lower temperature. Both the lamella thickness and the crystal size increase as the isothermal temperatures increase. The oligomer is apt to form a larger scale crystal under a low degree of supercooling. Additionally, the crystal morphology has an important relationship with the kind of substrate on which the oligomer grows, and it will also change with the variation of solvents in which tetraaniline dissolves.

Synthesis of Three Different Carbon Bridged Dinuclear Titanocene Complexes as Catalysts for Ethylene Polymerization

BAN Qing, SUN Jun-Quan

2003, 24(12):  2304-2307. 

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Three different dinuclear titanocene complexes (CH₃)₂C[(C₅H₄)TiCl₂(C₅H₅)]₂(3),(CH₂)·n[(C₅H₄)TiCl₂(C₅H₅)]₂(6, n=3; 7, n=4) were synthesized by the reaction of the corresponding dilithiumed salts with two equivalents of CpTiCl₃in toluene. The yield of the corresponding dinuclear titanocene complex in toluene is higher than that in THF, in which CpTiCl₃may be disproportionated to form Cp²TiCl₂. All titanocenes are characterized by ¹HNMR. The catalytic properties of the dinuclear titanocene complexes for ethylene polymerization were investigated in the presence of MAO(methylaluminoxane). For the ethylene polymerization catalyzed by compound 7/MAO, the catalytic activity increases with the increase of n(Al)/n(Cat.), the moleculer weight of polyethylene reaches 9.0102×10⁴. With the prolongation of the polymerization time, the catalytic activity declines while the molecular weight of polyethylene increases. At50 ℃, the molecular weight of the polymer reaches up to 7.77×10⁴. However, it decreases rapidly along with rising reaction temperature. When the length of the bridged ligand increases, the polymerization activity increases with the increase of the bridge length while the molecular weight decreases accordingly.

Preface

Synthesis and Photo-responsive Behavior of a Novel Main-chain Azo Polyester

HE Ya-Ning, WANG Hao-Peng, WANG Xiao-Gong, ZHOU Qi-Xiang

2003, 24(12):  2308-2311. 

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Anovel polyester with a high density of azobenzene groups in the main chain was synthesized by ester-interchange reaction of ethyl-4-4-[(2-hydroxyethyl)ethylamino]-phenylazobenzoate. The structure and properties of the azo polyester were characterized by ¹HNMR, GPC, TA, UV-Vis and others. On irradiation with a linearly polarized laser beam, birefringence was induced in the azo polymer film to the level of 007. Surface profile grating was optically inscribed upon exposure to an interference pattern of Ar⁺laser beam at modest intensities. The first order of diffraction efficiency of the surface relief grating was up to 18%.

Articles

Studies on the Sequence Structure and Crystallinity of Poly(butylene succinate) Copolymers with Terephthalic Acid

GUO Bao-Hua, DING Hui-Ge, XU Xiao-Lin, XU Jun, SUN Yuan-Bi

2003, 24(12):  2312-2316. 

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Aseries of high molecular weight polyesters, poly(butylene succinate)(PBS) and poly(butylene succinate-co-terephthalate)s(PBST), were obtained from succinic acid and/or dimethyl terephthalate reacting with 1,4-butanediol through a polycondensation process in the presence of a highly effective catalyst. The compostions and physical properties of both homopolyesters and copolyesters were investigated by ¹HNMR, gel permeation chromatography(GPC), differential scanning calorimetry(DSC), dynamic mechanical thermal analyzer(DMA), X-ray analysis and tensile test. Their number-average molecular weights are in the range of 1.25×10⁴-3.09×10⁴.The effect of copolymer composition on the thermal properties was investigated. The incorporation of rigid aromatic segments into aliphatic polyester was used for improving mechanical properties. Especially, the elongations at break(>500%) of the copolyesters(PBST) were much greater than that(80%) of the homopolyester(PBS).The results suggest that PBSTis a random copolyester and it has crystallinity in all the terephthalic acid contents.

Organic and Inorganic Hybrid Thin Film with NLO and Pyroelectric Properties

ZHAO Lei, WANG Shi-Min, XU Zu-Xun, FU Jing, WU Chong-Hao, CHENG Shi-Yuan

2003, 24(12):  2317-2320. 

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Anovel organic and inorganic hybrid material was prepared from a nonlinear optically active imidazole derivative 4HAPN and metal alkoxide of Ta(Ⅴ) via sol-gel process. The structure of hybrids film was analyzed by FTIR and SEM, the poled film exhibits a good oriention stability analyzed by electrochromic method. The permitivity and dielectric loss were calculated from measurements made with HP4192A Impedance Analyzer. The hybrid film shows low dielectric constants and low dielectric loss. The second order nonlinear and pyroelectric properties of the hybrid film were investigated in terms of the SHG and pyroelectric coefficient measurement. The SHG coefficient, d₃₃was found to be 17.2 pm/Vat the fundamental wavelength of 1064 nm and the pyroelectric coefficient was found to be 4.3×10^-6C/(cm²·K).

Single Crystal Structure of Crystalline Syndiotactic1,2-Polybutadiene

CHEN Ye, YANG De-Cai, HU Yan-Ming, ZHANG Xue-Quan

2003, 24(12):  2321-2323. 

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The crystalline syndiotactic 1,2-polybutadiene was synthesized with a catalytic system consisting of iron acetylacetonate, triisobutylaluminum and diethyl phosphite (DEP), and its single crystal structure was studied by transmission electron microscopy (TEM) and electron diffraction (ED) techniques. The polymer with melting point 179 ℃ was found to have 89.3% 1,2 content and 86.5% sydiotacticity based on ¹³CNMR measurement. The single crystals of the polymer were achieved by melt crystallization of the solution cast thin films at 150 ℃ for 2h. Bright field electron micrograph shows that the single crystal exhibits a hexagonal prism shape with its long axis along the crystallographic b-axis, as revealed by the corresponding ED pattern. The strong (hk₀) reflections of the ED pattern indicate that the single crystal possesses a very good crystallographic orientation with the c-axis perpendicular to the film plane. According to the orthorhombic packing of the planar zigzag chains, all of the diffraction points can be indexed, and the unit cell parameters calculated from the ED result are a=1.102 nm and b=0.664 nm. In order to obtain the unit cell parameter c, α highly oriented thin filMOf the polymer was prepared with a special melt drawn technique. The TEM bright field image indicates that the melt drawn thin films contain highly oriented lamellae with their growing direction perpendicular to the drawing direction. The corresponding ED pattern reveals the molecular chains are highly oriented, with the c-axis parallel to the drawing direction. The unit cell parameter c is 0.513 nm, as calculated from the (hk₀) reflections.

Influence of Nanostructured Polymer Surface on Cell Growth

LU Hai-Wei, LU Qing-Hua, CHEN Wan-Tao, XU Hong-Jie, YIN Jie

2003, 24(12):  2324-2326. 

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The nanogrooved surface of polystyrene(PS) petri-dishes was induced by an ultraviolet laser irradiation method. The influence of the surface nanostructure on the growth of the human tongue squamous cells carcinomas (HTSCC) was investigated. Cells cultured on laser-irradiated PS surface show an enhanced attachment and spreading in HTSCC cell culture test, and cell orientation was successfully controlled by selectively treating the PSsurface. We also prove that the nanostructures on polymer surface improved the cell attachment and spreading.

Synthesis and Properties of Degradable Graft Copolymer of Vinyl Acetate and Sericin

YAO Yan-Qing, BIAN Ping-Feng, CHEN Wen-Xing, LING Rong-Guo, SHEN Zhi-Quan

2003, 24(12):  2327-2329. 

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Degradable graft copolymers of vinyl acetate and sericin were prepared firstly. Their structures, mechanical and biodegradable properties, and thermal stability were examined by IR, TGand the tensile machine.The results indicate that the graft copolymers prepared have higher tensile strength, Young's modulus, elongation, thermostability and degradation rate than poly(vinyl acetate).

Synthesis and Characterization of Thermoplastic Chitin Derivative N,O-Benzyl Chitosan

DONG Yan-Ming, GUO Zhen-Chu, WU Yu-Song, RUAN Yong-Hong, TONG Bi-Hai, ZHAO Ya-Qing, WANG Hui-Wu

2003, 24(12):  2330-2332. 

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Chitin derivatives are difficult to be melten because of their very strong inter-molecular and intra-molecular hydrogen bonds. In this paper, N,O-benzyl chitosan was synthesized by means of phase-transfer method. The total degree of substitution for this derivative was 0.8 as determined with ¹HNMR and the degree of substitution on nitrogen was 0.3 as determined with elemental analysis. This is a thermoplastic chitin derivative. It's melting point was 470 Kas measured with DSC. Aviscous isotropic melt occurred at the temperatures between the melting point and the decomposition temperature(513K) while N,O-benzyl chitosan was heated on a hot stage. DSC results agreed with the results of microscopy observation. The benzyl group can not form hydrogen bonds. It is also non-polar and has larger volume. These factors weaken the interactions between chitosan chains, and therefore decrease the melting point, which was lower than the decomposition temperature. As a result, N,O-benzyl chitosan was able to melt.