Table of Content

24 February 2004, Volume 25 Issue 2

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Articles

Synthesis and Characterization of Sandwich Rare Earth Metal Mono-substituted Polyoxometalates with γ-[SiW₁₀O₃₆]^8- as Ligand

YUE Bin, JIANG Lei, KONG Zu-Ping, JIAO Feng, LIN Xin-Rong, JIN Song-Lin

2004, 25(2):  199-203. 

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Twelve rare earth metal mono-substituted polyoxometalates, K₁₃[Ln(γ-SiW₁₀O₃₆)₂]·nH₂O(Ln=La³⁺, Ce³⁺, Pr³⁺, Nd³⁺, Sm³⁺, Eu³⁺, Gd³⁺, Tb³⁺, Dy³⁺, Ho³⁺, Er³⁺, Yb³⁺), were synthesized by vacant sites-filling method by using γ- [SiW₁₀O₃₆]^8- as the ligand. The compounds were characterized by elemental analysis, UV-Vis absorption spectra, IR spectra, CV, paramagnetic measurement, fluorescence spectra and ¹⁸³W NMR. These results indicate that the rare earth metal ion is coordinated with eight terminal oxygen atoms of two γ- [SiW₁₀O₃₆]^8- ligands with D_2d symmetry and the title compounds have 1;2 sandwich structure.

Synthesis of ZnAPO-34 Films by Vapor-phase Transport Method

ZENG Chang-Feng, ZHANG Li-Xiong, WANG Huan-Ting, XU Nan-Ping

2004, 25(2):  204-207. 

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ZnAPO-34 films on dense alumina plates were synthesized by the vapor-phase transport(VPT) method. XRD and SEM were used to examine the powders and films. The water content in the synthesis had a strong influence on the crystal sizes and the morphology of ZnAPO-34 powders and films, and played a critical role on the successful preparation of a uniform ZnAPO-34 film. The optimum VPT synthesis was conducted at 170 ℃ for 24 h with the gel prepared as a composition of n(P₂O₅);n(Al₂O₃);n(ZnO);n(H₂O)=1;0.8;0.4 ;150 and the liquid phase composed of triethylamine and water [n(triethylamine);n(H₂O)=1;75]. Repeated synthesis cycles were necessary to obtain a continuous and uniform ZnAPO-34 film.

Hydrothermal Synthesis and Photoluminescent Properties of CaBPO₅;RE(RE=Eu,Tb) Phosphors

LIU Xiao-Tang, XIE De-Min, SHI Chun-Shan

2004, 25(2):  208-211. 

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CaBPO₅;RE(RE=Eu,Tb) phosphors were synthesized by hydrothermal method under a mild condition. The products were characterized by X-ray powder diffraction, scanning electron microscopy and luminescence spectrometer, etc.. Photoluminescence characteristics of the rare earth ions and sensitization of Ce³⁺ were investigated and compared with that of products prepared by solid state reaction at a high temperature. The results show that Eu³⁺, Tb³⁺ and Eu²⁺ co-exist in one matrix because there is an electron transfer process between Eu³⁺and Tb³⁺. It is interesting that the emission spectrum is peaked at 428 nm for Eu²⁺ in CaBPO₅;Eu,Tb prepared by hydrothermal method. Sensitization of Ce³⁺ improves the intensity of emission of Eu³⁺, Tb³⁺ and Eu²⁺. The reasons maybe are the competitions between the electron transfer among conjugate rare earth ions and the energy transfer between Ce³⁺ and Eu³⁺, Eu²⁺ and Tb³⁺.

Hydrothermal Synthesis and Crystal Structure of a New Mixed-valent Copper Complex [Cu^ⅠCu^Ⅱ(Ophen)₂Cl]·H₂O (HOphen=2-Hydroxy-1,10-phenanthroline)

DEGE Jihu, HUANG Ru-Dan, LI Yang-Guang, WANG En-Bo, HU Chang-Wen, XU Lin

2004, 25(2):  212-215. 

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A new mixed-valent copper complex [Cu^ⅠCu^Ⅱ(Ophen)₂Cl]·H₂O(HOphen=2-hydroxy-1,10-phenanthroline) was hydrothermally synthesized and its structure was characterized by the single crystal X-ray diffraction. The compound crystallizes in the triclinic system, space group P1 with a= 0.916 67(18) nm, b=1.054 6(2) nm, c=1.170 5(2) nm, α=80.50(3)°, β=80.56(3)°, γ=66.87(3)°, V= 1.020 2(3) nm³, Z=2, D_c=1.872 Mg/m³, R₁(wR₂)=0.050 8(0.148 1). The title compound consists of a new dinuclear copper complex [Cu^ⅠCu^Ⅱ(Ophen)₂Cl]·H₂O and one crystal water. Furthermore, two such complexes form a dimer via the van der Waals interactions between Cu…Cu centers. Furthermore, such dimers are stacked into a 3D supramolecular frameworks via the π-π interactions between adjacent Ophen groups and the weak C—H…Cl intermolecular forces. The water molecules are resided into the cavities of the frameworks.

Synthesis and Crystal Structure of Dinuclear and Trinuclear Ruthenium Carbonyl Clusters with P, S-Contained Ligand

HAN Rui-Min, WU Bing-Fang, HU Xiang, LIU Shu-Tang

2004, 25(2):  216-220. 

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The reactions of carbonyl ruthenium Ru₃(CO)₁₂ with two cyclic dithiophosphinate SP(C₆H₄OR)(S)N(C₆H₅)N C(Me)(R=Me, Et) yields four novel dinuclear and trinuclear ruthenium carbonyl clusters with P, S-containing lignads Ru₃(CO)₈(μ₃-S)₂ [ P (C₆H₄OR)N(C₆H₅)NC(Me)S](1; R=Me; 3; R=Et) and Ru₂(CO)₆ [μ-η₂-P(C₆H₄OR)N(C₆H₅)NC(Me)S](2; R=Me; 4; R=Et). These clusters were characterized by elementary analysis, IR, ¹H NMR and MS spectroscopy. The crystal structures of clusters 1 and 2 were determined by X-ray diffraction techniques. The crystal of cluster 1 belongs to triclinic system with space group P1, a=1.075 5(2) nm, b=1.576 0(2) nm, c=0.907 8(1) nm, α= 98.12(7)°, β=96.64(4)°, γ=79.67(5)°, V=1.492 1(4) nm³, Z=2, R(wR)=0.030 3(0.061 5). The molecule consists of a opened triangle of ruthenium atoms capped above and below the plane by sulphur. Ru₃(μ₃-S)₂ core is a distorted square pyramid geometry. The site of five-membered hetero cyclic phosphine substitution is equatorial to the tri-ruthenium plane and is at an axial site of Ru1. The crystal of cluster 2 belongs to monoclinic system with space group P2(1)/n, a= 1.124 3(4) nm, b=1.410 5(5) nm, c=1.629 45(7) nm, β=107.06(5)°, V=2.470 2(2) nm³, Z=4, R(wR)=0.024 8(0.044 1). The dinuclear cluster contains two six-membered chelate rings Ru1SCNNP and Ru2SCNNP, they enhance the stability of the cluster.

Crystal Structures and UV-Vis Spectral Properties of Sulfato and Carbonato Bridged Dinuclear Iron(Ⅲ) Complexes

PENG Yi, YAN Shi-Ping, LIAO Dai-Zheng, JIANG Zong-Hui, CHENG Peng

2004, 25(2):  221-226. 

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Sulfato and carbonato bridged dinuclear iron(Ⅲ) complexes {2[(TPA)₂Fe₂O(SO₄)]·(ClO₄)₂·1.5H₂O (1), [(TPA)₂Fe₂O(CO₃)](ClO₄)₂·CH₃OH (2)} were synthesized at room temperature. The crystal structures were characterized by X-ray diffraction structural analyses. Complex 1 crystallized in the monoclinic space group P2₁/c with a=1.150(2) nm, b=2.659(5) nm, c= 2.933(5) nm, and β=99.40(3)°. The structure was determined at 293 K from 15.503 out of a total of 36.459 reflections with R=0.056 4, wR=0.110 6. Complex 2 crystallized in the monoclinic space group P2₁/c with a=1.136 8(3) nm, b=1.828 0(5) nm, c=2.054 2(5) nm, and β=94.867(5)°. The structure was determined at 293 K from 7.420 out of a total of 17.309 reflections with R=0.056 7, wR=0.136 2. Complexes 1 and 2 were compared with some (μ-O) dinuclear iron complexes in crystal structures and the UV-Vis spectra were recorded at room temperature.

Synthesis of Cobalt Nanocrystals by High Temperature Solution Phase Reducing Method and Their Two-dimensional Ordered Superlattices

SU Yi-Kun, SHEN Cheng-Min, YANG Tian-Zhong, YANG Hai-Tao, GAO Hong-Jun, LI Hu-Lin

2004, 25(2):  227-229. 

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The monodisperse magnetic cobalt nanocrystals(NCs) of 7 nm in diameter were prepared by using high temperature solution phase reducing method. The UV-Vis spectrum showed that the cobalt NCs was stable. The structure of the cobalt NCs were determined by XRD. The results showed that each of the cobalt nanoparticles is a single crystal with a complex cubic structure relating to the β phase of manganese. The XPS spectra indicate that the surface of Co nanoparticles was not oxidized or formed other compound. Two-dimensional order superlattices of the Co nanoparticles were formed by self-assembly technique.

Hydrothermal Synthesis and Structure Characterization of C₄H₈N₂H₄·Zn(HPO₃)₂

SHI Su-Hua, LI Guang-Hua, XIN Ming-Hong, LI Yue-Ming, DING Hong, XU Jia-Ning, ZHU Guang-Shan, SONG Tian-You, QIU Shi-Lun

2004, 25(2):  230-232. 

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A new zinc hydrogen phosphite C₄H₈N₂H₄·Zn(HPO₃)₂ was prepared by hydrothermal method in the presence of piperazine as a structure-directing agent and the crystal structure was determined by single-crystal X-ray diffraction analysis and further characterized by X-ray powder diffraction, IR, ICP, elemental analysis and TG analysis. This compound has one-dimensional anionic chains containing four-membered rings built from corner-sharing linked alternating ZnO₄ tetrahedra and HPO₃ pseudo pyramids. The zinc hydrogen phosphite chains are interacted with the templates of diprotonated piperazine by N—H…O hydrogen bond. Crystal data for C₄H₈N₂H₄·Zn(HPO₃)₂;monoclinic, space group C2/c. a=1.774 8(2) nm, b=0.724 28(9) nm, c=0.880 87(11) nm, β= 105.345(3)°, V=1.091 9(2) nm³, Z=4, D_c=1.907 Mg/m³, R₁=0.022 9, wR₂=0.058 8.

Simultaneous Separation and Determination of Arginine and Methylated Arginines in Human Plasma with LC-APCI-MS Method

HUANG Lan-Fang, LIANG Yi-Zeng, GUO Fang-Qiu, CHEN Ben-Mei

2004, 25(2):  233-237. 

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A simple, sensitive and fast high-performance liquid chromatography-mass spectrometry method was developed for simultaneous separation and determination of L-arginine(ARG), asymmetric N^G,N^G-dimethylarginine(ADMA) and symmetric N^G,N′^G-dimethylarginine(SDMA) in human plasma. An APCI interface and the selective ion monitoring(SIM) mode were used. Satisfactory separation was achieved on a 2.0 mm×150 mm Shimadzu VP-ODS column by using the mobile phase consisting of water(95%), acetonitrile(5%) and trifluoroacetic acid(TFA, 0.4%). L-Homoarginine was used as the internal standard for the assay. The total LC-APCI-MS analysis time was less than 5 min. The limits of quantification(LOQ) were found to be 0.2 μmol/L for ARG, ADMA and SDMA. The inter- and intra-assay precisions were in the range of 2.9%—6.7% and 2.1%—5.2%, respectively. The recoveries were between 94.0% and 105.0%. The levels of ARG, ADMA and SDMA in human plasma were determined with the developed method and the results were satisfactory.

Optimization Method of Multi-segment Gradient for Separation of Ginsenosides in Reversed Phase-High Performance Liquid Chromatography

MA Xiao-Qiong, WANG Long-Xing, XU Qing, ZHANG Feng, XIAO Hong-Bin, LIANG Xin-Miao

2004, 25(2):  238-242. 

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A multi-segment gradient method for the separation of ginsenosides in reversed phase-high performance liquid chromatography(RP-HPLC) was developed. The retention parameters of 8 ginsenosides(Rg1, Re, Rf, Rg2, Rb1, Rc, Rb2 and Rd) were obtained on an ODS2 C18 column(4.6 mm×250 mm) from a series of isocratic acetonitrile-water elution. It is found that two-parameter retention equation of ginsenosides can′t be used to accurately predict the resolution, but the three-parameter retention equation can. The reason is that the retention factor k′ decreases fast while the volume fractions of acetonitrile increase in mobile phase, which make the precision of two-parameter retention equation can′t satisfy the predicting need of resolution. Based on the three-parameter retention equation, an optimum elution program consisting of three segments was developed. Under the optimized gradient conditions, the retention time and resolution of ginsenosides are in good agreement with the predicted ones. The analysis time of ginsenosides is shortened and the resolution is improved by the method.

Interaction Between DNA and Terbium(Ⅲ)-Ciprofloxacin Fluorescence Complex and New Tissue Staining Method

YANG Jun, REN Yu, XU Yi-Zhuang, SU Yun-Lan, ZHANG Li, LIU Zhi, WANG Fan, YANG Li-Min, WANG Jing, GAO Hong-Cheng, YE Fang, WU Jin-Guang

2004, 25(2):  243-246. 

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A new lanthanide complex that gives off green fluorescence upon exciting by UV radiation was synthesized by using terbium chloride and ciprofloxacin. The complex binds firmly on DNA and induces conformation changes of DNA based on the analysis of FTIR and fluorescence spectra. Strong fluorescence from terbium ions can be observed from the resultant composite under UV light. Thus, it is possible that the terbium ciprofloxacin complex can be developed as a fluorescent dye in biological and pathological studies. The results indicate that the complex is concentrated on the nuclei regions in the sections of oral tissues and the nuclei are highlighted under fluorescent microscope.

Studies on the Characteristics of Co, Ni and Cu Adsorption to Natural Surface Coatings

DONG De-Ming, JI Liang, HUA Xiu-Yi, LI Yu, ZHENG Na

2004, 25(2):  247-251. 

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Surface coatings developed in the Nanhu Lake(Changchun) were used to study the characteristics of thermodynamics and kinetics of Co, Ni, and Cu adsorption to them. Statistical analysis of the adsorption data show that the thermodynamic data of each metal fit the Langmuir isotherms. At low ion concentrations(<0.5 μmol/L), the adsorption capacity of these metals to the surface coatings decreased in the order Co, Cu, and Ni, while at high ion concentrations(>0.5 μmol/L), the capacity decreased in the order Cu, Co, and Ni. The kinetic data indicate that the adsorption reached equilibrium in several hours. Four kinetic models, i.e., Elovich equation, double-constant rate equation, first-order kinetics equation and Langmuir kinetics equation, can all be used to describe the adsorption process, especially the Langmuir kinetics equation.

Matrix Effects of Micro-sampling System for Inductively Coupled Plasma Mass Spectrometry

KANG Jian-Zhen, DUAN Tai-Cheng, GUO Peng-Ran WANG Chang, CHEN Hang-Ting, ZENG Xian-Jin

2004, 25(2):  252-255. 

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Matrix effects of inductively coupled plasma mass spectrometry(ICP-MS) with the self-installed micro-sampling system at 22 μL/min of solution uptake rate were studied. In the presence of 2 g/L matrix elements with different masses or ionization potentials, the signal intensity of analyzed elements was measured. For light analyzed elements, the interferences were observed; while for high mass analyte elements, the normalized intensity was close to 1. In the presence of 5% organic matrix, the normalized intensity was near to 0 5. When common elements such as K, Na, Ca, Mg at 500 mg/L or 1% organic solvents such as ethanol and acetic acid existed in the solution, the signals of analyzed elements were almost not affected. The results show that the micro-sampling system has a good capability of anti-interference to matrixes.

Enantiomeric Separation of Galantamine in Drug for Alzheimer's Disease and Its Quality Control by Capillary Electrophoresis

YAN Liu-Shui, ZHAO Ji-Yuan, LUO Guo-An, SUN Ming, WANG Yi-Ming, YANG Xue-Dong

2004, 25(2):  256-260. 

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A method for capillary electrophoretic enantiomeric separation of a novel drug for Alzheimers disease, Galantamine, has been established with α-cyclodextrin as the chiral additive. General equations and data analysis approach are presented to relate molibilities to equalibrium constants in simple binding equilibria and used to determine bonding constants and thermodynamic parameters for host-guest complexation of galantamine enantiomers with cyclodextrin selector. The effects of cyclodextrin concentration and type, buffer concentration and its pH, and separation voltage were investigated. The mechanism of enantioselectivity is discussed by combining with the computer simulating conformational analysis. The maximal resolution of 3.60 was obtained . The bonding constants of host-guest complex of galantamine enantiomers with α-cyclodextrin, K_R-CD and K_S-CD, is 33.98 L/mol and 23.90 L/mol, respectively. The established method was successfully applied to the detect ion of the non-effective component in the raw material of galantamine. Ten structural analogues were found, and the content of R enantiomer is 0.82%. The concentration linear rang is 0.015—1.0 mmol/L with the analysis precision of 0.20% and 2.6% for the measurement of migration time and peak area, respectively. Thus, the method could be used as a rapid and reliable tool for quantity control of the drug.

Stopped-flow Liquid-liquid Extraction on Microfluidic Chips

FANG Qun, CHEN Hong, CAI Zeng-Xuan

2004, 25(2):  261-263. 

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In this work, two novel approaches were developed for miniaturized liquid-liquid(L-L) extraction on microfluidic chips, based on a stopped-flow extraction technique. In the first approach, trapped droplets extraction mode, organic solvent droplets of a few hundred 10^-12 L were trapped within micro recesses fabricated in the channel walls of microfluidic chips, and analytes in aqueous streams flowing over the droplets were transferred into them, affecting a preconcentration. In the second approach, a stable interface between stationary organic phase and continuously flowed aqueous phase was formed by stopping the flow of organic phase. Analytes were transferred from the aqueous phase into the organic phase on the interface. Enrichment factors exceeding 1 000 and 300 were achieved with a preconcentration period of 20 min with sample consumption lower than 10 μL for trapped droplets and stopped-flow microextraction. In situ laser induced fluorescence detection of the concentrated analyte was performed following the preconcentration.

A Novel Aerodynamic Force Capillary Microdrop-injection Determination of Ethamsylate with Chemiluminescence

HUN Xu, YANG Wei-Ping, ZHANG Zhu-Jun

2004, 25(2):  264-266. 

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A novel aerodynamic force capillary microdrop-injection-chemiluminescence(AFCM-CL) system for the determination of ethamsylate was proposed in this paper. In this system the ethamsylate microdrop formed at the end of the capillary droped into the reactor cell by the force of the gravity and the high press gas automatically. Then the ethamsylate was directly oxidized by dissolved oxygen in the presence of hexacyanoferrate(Ⅲ) to generate a CL signal in sodium hydroxide medium. The phenomena of sample zone dilution and spreading disappeared as the capillary was used as the sample channel and gas pressure was used as driving force without the carrier stream. Therefore, a high sensitivity was obtained compared with the FI-CL method. The analysis sample volume is only about 8 μL and the sample throughput is 180 h^-1. The system shows that the ethamsylate is detected linearly in the mass concentration range from 5×10^-10—1×10^-6 g/mL. The detection limit is 1.4×10^-10 g/mL(1.1 pg). The relative standard deviation is 3.1% at 2.5×10^-8 g/mL(n=7).

Studies on the Kinetics and Mechanism of Intermediates of Rexaction between Oxyhemoglobin and H₂O₂ Using Stopped-flow Time-resolved Spectrophotometry

WANG Rui-Yong, CAI Ru-Xiu, LIN Zhi-Xin

2004, 25(2):  267-269. 

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Interaction between oxyhemoglobin and H₂O₂ was studied by the aid of stopped-flow time-resolved spectrophotometry. The consecutive reaction kinetics of oxyhemoglobin with H₂O₂ suggested the presence of an intermediate species. The influence of pH, concentration of H₂O₂, and temperature on the pseudo-first order rate constants was studied. The kinetic experiments performed at different temperatures allowed to calculate the activation energy. A reasonable mechanism was also proposed.

Fast Identification of Polymorphic RAPD Fragments of P. Taiwanensis Hayata Using an Integrated Microfluidic Chip-based System

LIU Jin-Hua, YIN Xue-Feng, TANG Juan-Juan

2004, 25(2):  270-272. 

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The microfluidic chip-based system in conjunction with the t-test, was found applicable to identify the polymorphic RAPD fragments from P. Taiwanensis Hayata, whose polymorphism was weak and the sizes of each allele were unknown. The suggested microchip electrophoresis was very sensitive, and it requires much less sample and only a quarter of the time compared to the agarose gel method. The standard deviations of the fragment sizes and peaks area, for replicates number 10, ranged from 0.97%(701 bp) to 1%(301 bp) and 10%(301 bp) to 11.9%(701 bp), respectively. The average values of three alleles in the polymorphic RAPD fragments were identified as 301, 708 and 1069 bp with standard deviations of 3, 7, and 12 bp.

Reaction Between Pyridinium N-Ylides and 1,4,4a,8a-Tetrahydro-1,4- methanonaphthalene-5,8-dione in the Presence of Oxidant

WANG Bing-Xiang, HU Hong-Wen

2004, 25(2):  273-275. 

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Some tricyclic indolizine compounds having sPLA₂ inhibitory activities have been reported. A general method for preparing multi-cyclic indolizine compounds(1a—1c, 2a—2b and 3) in moderate yields(45%—71%) by a 1,3-dipolar cycloaddition reaction of pyridinium N-ylides, isoquinolinium N-ylides or quinolinium N-ylides to 1,4,4a,8a-tetrahydro-1,4-methanonaphthalene-5,8-dione, followed by an aromatization, in the presence of tetrakispyridine cobalt(Ⅱ) dichromate(TPCD) is described. The method features cheap reagents ,simple workup procedure. The above compounds(1a—1c, 2a—2b and 3) are of great value for evolution in medicinal research studies.

Synthesis of Novel Type ALS Inhibitors Based on Pharmacophore Model Design

CHENG Yong-Hao, CHEN Kai, LI Yong-Hong, ZOU Xiao-Mao, YANG Hua-Zheng

2004, 25(2):  276-280. 

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Derived from the postulated ALS inhibitors′ pharmacophore model, the generalized function-based queries were defined and used for three-dimensional(3D) searching in two different 3D databases(NCI-3D and ACD-3D). More than 100 novel structural hits were found by performing different 3D searching programs(3DFS and ISIS/3D). The novel structure hits provide a lot of structural information, the novel type ALS inhibitors were designed and synthesized by the information. The preliminary bioassay data indicate that some compounds with an anticipated good biological activity have ALS inhibitions in some degree.

Synthesis and Biological Activities of Bis[4-hydroxy-5,6-dihydro-6- alkyl(aryl)-2H-pyran-2-one-3-] methane

LI Yu-Xin, WANG You-Ming, WANG Su-Hua, YANG Xiao-Ping, LI Zheng-Ming

2004, 25(2):  281-283. 

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We attempted to build a carbon-carbon single bond in 3 position of 5,6-dihydro-6-alkyl(aryl)-2H-pyran-2,4-diones by Mannich reaction, but failed to gain the title compounds and the unexpected products were obtained. 5,6-Dihydro-6-alkyl(aryl)-2H-pyran-2,4-diones with aldehydes and a series of bis[4-hydroxy-5,6-dihydro-6-alkyl(aryl)-2H-pyran-2-one-3-] methanes were obtained. Their structures were confirmed by ¹H NMR spectra and elemental analyses. In order to discuss this new condensation reaction, its reaction conditions were discussed. Compounds 3 were tested in vitro against many fungi such as P. Zeae, C. Arachidicala, P. Piricola, A. Solani, B. Cinerae, S. Sclerotiorum and H. Oryzae. The bioassay results show that they have some fungicidal tobacco virucidal activities.

Studies on Flavonoids from Sophora Flavescens Ait Using ESI-MS~n

BAI Yu, GUO Ming-Quan, SONG Feng-Rui, LIU Zhi-Qiang, LIU Shu-Ying

2004, 25(2):  284-288. 

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Two kinds of flavonoids from Sophora Flavecens Aits, dihydroflavonoids and dihydroflavonols, were studied by using electrospray ionization tandem mass spectrometry(ESI-MSⁿ). [M-H]^- of these two kinds of flavonoids were observed in the negative ion mode under ESI conditions, which provided us the molecular weights of them. Cross-ring reactions, arisen from MS² spectra of both dihydroflavonoids and dihydroflavonols, gave the fragment ions by the loss of neutral species. The differences of their cleavage positions were then proposed, dihydroflavonoids cleave at C2—O bond and C4—C10 bond, but dihydroflavonols cleave at C2—O bond and C3—C4 bond. The loss of neutral species from dihydroflavonoids and dihydroflavonols were also discussed, the former were several relative big neutral species, while the latter were some small species, such as CO, CO₂, H₂O and B-ring. The differences between dihydroflavonoids and dihydroflavonols were mainly arisen by hydroxy group at C-3 of the C-ring, which were the characteristic for dihydroflavonoids and dihydroflavonols under the ESI-MS n conditions.

Studies on Preparation and Property of Azobenzene-contained Pullulan Derivatives

JIAO Yong-Hua, ZHANG Li-Mei, JIANG Zhen-Hua

2004, 25(2):  289-291. 

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Azobenzene-modified pullulan with different substitution degrees were prepared by changing feed molar ratio of 4-phenylazophenyloxybutyrate acid to pullulan. The structure of the modified pullulan were characterized by ¹H NMR and FTIR spectroscopies. The substitution degrees were determined by elemental analysis and UV-Vis spectra. Photochromism property in solution was investigated by UV-Vis spectroscopy, isomerization behavior of azobenzene moeties of polymer under irradiation at 350 nm is obvious. After 4 min irradiation, trans isomer of sample 3 change into cis isomer completely. Furthermore, unlike pullulan, which is soluble only in H₂O or DMSO, the solubility of these products in common organic solvent increased greatly.

Total Syntheses of (±)-3,5-Dihydroxy-7,4′-dimethoxy-dihydroflavonol and (±)-3,5,7-Trihydroxy-4′-methoxy-dihydroflavonol

ZHANG Ying-Peng, LI Ying, XUE JI-Jun, NIU Ying-Hui, WU Jiang

2004, 25(2):  292-293. 

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Dihydroxy-7,4′-dimethoxy-dihydroflavonol and (±)-3,5,7-trihydroxy-4′-methoxy-dihydroflavonol were found in many medicinal plants, here we describe a concise synthesis route by selective protection, aldol-condensation, 30% H₂O₂ epoxidation, cyclization and deprotection from²,4,6-trihydroxyacetophone and anisaldehyde.

Synthesis of Several Novel Benzoylurea Chitin Inhibitors(ê)

XU Rong, LIN Jun, MAO De-Shou, YAN Sheng-Jiao, ZONG Qian-Shou, YANG Li-Juan, LIU Fu-Chu

2004, 25(2):  294-296. 

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Chlorothalonil 1 was treated with anhydrous KF in DMF at 110 ℃ to give the corresponding crystalline fluorine-containing 1,3-benzenedicarbonitrile 2. KF was used in an equivalent to the number of chlorine atoms to be substituted. Compound 2 was subsequently reacted with ammonia to yield compound 3. In addition, halobenzamide 4 were refluxed with oxalyl chloride in anhydrous 1,2-dichloroethane(DCE) to yield benzoylisocyanates 5. Finally, seven novel BPUs chitin inhibitors 6a—6g were synthesized via the selective reaction of compound 3 with benzoylisocyanate derivatives 5, the total yield is over 30%—50%.

Preparation of α-Nitroketene Dithioacetals

ZHAO Yu-Long, LIU Qun, SUN Ran, CHI Ying-Nan

2004, 25(2):  297-298. 

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Nitroketene dithioacetals(2) were prepared in moderate to high yields by nitrodeacetylation reaction from α-acetyl ketenedithioacetals(1) when treated with mixed acid in dichloromethane at room temperature. This reaction involves an electrophilic addition-deacetylation mechanism and shows the nucleophilicity of the α-carbon atom in α-oxo ketenedithioacetals.

A Scheme for Jointed Two Component-scalar Relativistic Density Functional Calculations of Systems Containing Heavy Elements

WANG Fan, LI Le-Min, LIU Wen-Jian

2004, 25(2):  299-303. 

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A scheme for joined two component-scalar relativistic density functional calculations of systems containing a few heavy atoms is proposed based on the relativistic density functional ZORA method with an atomic model potential approximation. The two component-relativistic density functional computation is performed only for a few heavy atoms with strong spin-orbit effects in the system, while the reminder part of the system is treated with the scalar relativistic density functional method, resulting in considerably reduction of computational efforts. The two kinds of computations are joined through a reasonable approximation in the calculation of kinetic energy matrix elements. The calculations for a series of molecules containing 6p block heavy elements are performed by using the proposed scheme and the normal two component-ZORA method. It is found that the results from the two kinds of calculations are in excellent agreement to each other when the lighter atoms belong to the second or third period. If the “non-heavy” atoms belong to the fourth period, the results from the proposed scheme slightly deviate from those obtained by the normal two component-ZORA calculations, showing that the spin-orbit effects have become significant relatively and cannot be neglected in the calculations with a high accuracy required. However, even in that case, the accuracy of the calculated results is still compatible with that of the current approximate density functionals and can satisfied the requirement for ordinary theoretical studies. The proposed scheme can effectively save computation efforts while the defects in Dyall′s method can be avoided.

Studies on Hydrothermal Electrodeposition of Hydroxyapatite Coatings

LIU Rong-Fang, XIAO Xiu-Feng, LIN Lan-Yun, CHEN Gu-Yong

2004, 25(2):  304-308. 

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Hydroxyapatite coatings were formed on titanium electrode by using the hydrothermal electrodeposition method in an autoclave. The electrolyte contained 0.010 5 mol/L Ca(NO₃)₂, 0.006 3 mol/L NH₄H₂PO₄ and 0.1 mol/L NaNO₃. The electrolyte temperature was controlled at 60—200 ℃ and pH value was adjusted at 4.6. After loading of a constant current at 0.4 mA/cm² for 2 h, the deposits were characterized by XRD, FTIR, environment scanning electron microscopy and energy dispersive X-ray spectroscopy. The experiment results show that the deposit crystals are rods in shape, the edge face of rod is a defined flat hexagon and the width and length of the crystal rods increases continuously with increasing the electrolyte temperature. The component of coatings is calcium-deficient hydroxyapatite [Ca_10-x(HPO₄)_x(PO₄)_6-x(OH)_2-x, 0≤x≤1], which decomposed into the mixture of hydroxyapatite and β-calcium phosphate after sintering at 800 ℃. The n(Ca)/n(P) ratio of the coatings increased and was close at 1.67 with the electrolyte temperature increasing. These results suggest that the component of coating is continuously close to stoichiometric hydroxyapatite with the electrolyte temperature increasing. Furthermore, mass gain of the coatings and bonding strength of coatings increase with electrolyte temperature increasing up to 160 ℃. The bonding strength of coatings after sintering at 800 ℃ for 6 h attained 16.7 MPa when the electrolyte temperature was controlled at 160 ℃.

Theoretical Study on the Ground State Energy Splitting of 9-Hydroxyphenalenone

LIU Hai-Ying, DING Shi-Liang, LI Yan

2004, 25(2):  309-312. 

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Proton transfer is the most general and important reaction in chemistry. This work presented a sextic function to describe the potential energy surface(PES) of proton transfer. The picture of the sextic function V(R,γ)=R⁶+2(R⁴+(γ²+μ)R² is a double-well curve, when γ and μ satisfy specific conditions. Moreover, its corresponding Schrdinger equation has exactly analytic solutions via transformation. But to the generally used quartic function V(R)=A(R⁴-BR²), the corresponding Schrdinger equation can′t be solved exactly. Combined this potential function with one-dimensional double-well model and variational method, the energy splitting of the ground state of 9-hydroxyphenalenone, which is a typical system of intramolecular proton transfer, was studied in this work. The structure and energy were calculated with density-functional theory(DFT) at the B3P86/6-311G level for the equilibrium configuration and the transition state. The produced barrier height was 722.85 cm^-1. The energy splitting obtained Δ_H(0)=86.13 cm^-1 was satisfactorily compared with the experimental observations and other theoretical values.

Theoretical Study on Structures and Stabilities of Molecule SiCS

CHEN Guang-Hui, HUANG Xu-Ri, SUN Chia-Chung

2004, 25(2):  313-315. 

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The singlet and triplet PESs of SiCS were investigated by the DFT, QCISD and CCSD(T) levels. At the QCISD level, it is shown that total five minimum isomers are connected by 3 transitional states. The global minima is a linear triplet isomer SiCS ³1 followed by a second low-lying singlet linear SiCS(¹1) and a cyclic isomer cSiCS(¹2).

A Revised Formulation for TST Involving the Non-equilibrium Effects in the Activated Complexation Process

ZHAO Nan-Rong, LUO Jiu-Li

2004, 25(2):  316-319. 

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The activated complex as a transition state in chemical kinetics processes is actually at a kind of non-equilibrium steady state. In this paper, the non-equilibrium statistical problems concerning with the non-equilibrium behavior of the activated complex was commented at the level of phenomenological theory. By analyzing the effects on the reaction rate from the dissipation-fluctuations in the activated complexation process, we further proposed a revised formulation for TST in which the non-equilibrium effects of the activated complexation process were involved. As a result, a basic relationship between reaction rate and non-equilibrium dissipation function, instead of equilibrium constant, of the activated complexation, was established. Finally, the statistical “drift” of the reaction rate constant induced by what influence the dissipation-fluctuations in the activated complexation process was also discussed briefly.

Synthesis and Characterization of Cu(Ⅱ)-contained MCM41 with High Content of Copper

KONG Yan, CHEN Jia-Yi, GUO Xian-Ji, MA Hui-Xuan, HOU Wen-Hua, YAN Qi-Jie

2004, 25(2):  320-324. 

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A series of Cu-containing MCM41 with high contents of copper was synthesized at room temperature by using Na₂SiO₃ as Si sources and Cu(NH₃)₄(NO₃)₂ as Cu sources and cetyltrimethyl ammonium bromide(CTAB) as the template. The influence of reaction conditions such as time, temperature, pH value and copper contents upon the structure of the materials was systematically studied. The mesoporous material containing up to 26%(mass fraction) copper was successfully synthesized under the best reaction conditions(t=20 ℃; pH=9—10; t=72 h). The structure of the materials was characterized by XRD, HRTEM, BET, TG-DTA, FTIR, ICP and XPS. The obtained material has a high surface area of 525 m²/g with a narrow pore distribution at 3.11 nm.

Preparation and Characterization of Monolithic TiO₂/SiO₂ Aerogels Obtained by Non-supercritical Drying Method

WANG Yu-Dong, CHEN Long-Wu, GAN Li-Hua, HOU Ji-Xiao

2004, 25(2):  325-329. 

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TiO₂/SiO₂ aerogels, a special kind of mesoporous materials, is comprised of linked nano-sized pores which possess a high photocatalytic activity. In our work, sols of TiO₂ and SiO₂ were prepared separately and mixed to prepare TiO₂/SiO₂ gels. Formamide as the drying control chemical additive(DCCA) was added to stiffen the microstructure of TiO₂/SiO₂ gels. TiO₂/SiO₂ gels were immersed in the tetraethoxysilane/ethanol solutions, exchanged pore fluid with low surface tension solvent, aged and then dried in different stages to realize the preparation of TiO₂/SiO₂ aerogels by non-supercritical drying. The resultant aerogels were transparent or translucent, highly porous and low density foams with bulk densities in the range of 0.4—0.9 g/cm³ and porosity about 80%—95%. The TiO₂/SiO₂ aerogels were comprised of dispersed TiO₂ and SiO₂ particles. The average particle diameter is about 10 nm, and average pore diameter is tens of nanometers. The phase of SiO₂ is amorphous and TiO₂ remains anatase microcrystal until 800 ℃. The effects of molar ratio of TiO₂ to SiO₂ and amount of formamide on sol-gel process and aerogel properties were also discussed.

Studies on Relationship Between Temperature and Pressure of the Supercritical CO₂+EtOH+CO+H₂ Quaternary System and Its Super-critical Properties

ZHANG Jing-Chang, ZHANG Jian-Jun, LIU Wei-Wei, CAO Wei-Liang

2004, 25(2):  330-333. 

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The dependent relationship between temperature and pressure of supercritical CO₂+EtOH+ CO+H₂ quaternary system in the pressure range from 5 to 11 MPa in densities of CO₂ ranging from 0.542 to 0.590 g/cm³ was investigated by the static visual method in a constant volume. The critical temperature and pressure were experimentally determined simultaneously. The molar fraction of ethanol is 0.2% and that of CO and H₂ whose molar ratio is 1;1 changes from 0 to 4%. The phase behavior of the hydroformylation of propylene in supercritical CO₂ was simulated. It was found that the addition of CO and H₂ could change the supercritical properties of the CO₂+EtOH+CO+H₂ quaternary system obviously. Its critical temperature decreases linearly while its critical pressure increases linearly with the increasing molar fraction of CO and H₂. It was also found that pressure of the quaternary system in definite density of CO₂ increases linearly with increasing temperature and the slopes of p-T lines were basically the same. Simultaneously, pressure of the same quaternary system increases linearly with the increasing molar fraction of CO and H₂ in definite temperature and the rates of change at different temperatures were almost identical.

Electrochemical Storage Hydrogen of the Aligned Multi-walled Carbon Nanotubes

LIU Jing, MAO Zong-Qiang, HAO Dong-Hui, ZHANG Xian-Feng, XU Cai-Lu, WU De-Hai

2004, 25(2):  334-337. 

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The mechanism of electrochemical storage hydrogen in the aligned multi-walled carbon nanotubes(AMWCNTs) was investigated by using charge-discharge test, cyclic voltammetry(CV) and electrochemical impedance spectra. A high discharge capacity of 1 162 mA·h/g of the AMWCNTs-Cu was obtained at a current density of 1 500 mA/g. The high capacity of the AMWCNTs is related to the space structure. The addition of copper power into the AMWCNTs is advantageous to increase the electro-catalyzed reaction areas of the AMWCNTs electrode and improve its electrochemical activity. The copper powder could also accelerate the diffusion of hydrogen in AMWCNTs-Cu electrode, so the AMWCNTs-Cu electrode has a higher capacity of storage hydrogen.

Spectral Study of 5,10,15,20-Tetra(p-Chlorophenyl) PorphyrinLanthanide Complexes

JIA Hui-Ying, XU Wei-Qing, QI Ming-Hui, LIU Guo-Fa, LI Xiao-Ling, ZHAO Bing

2004, 25(2):  338-341. 

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The UV-Vis spectra, Infrared spectra and resonance Raman spectra of tetra(para-chlorophenyl)porphyrin and its coordination compounds LnT(%p%-Cl)PPOH(Ln; Tb, Lu, Er, Gd) were measured and investigated respectively. In UV-Vis spectra the effect of rare earth ions were discussed. Metal sensitive bands in IR spectra were found, and the effect of metal ion size on the marker bands frequencies in resonance Raman spectra was also discussed.

Visible Light Induced Photocatalytic Oxidation of Ethylene over Pt/Pt ⁴⁺-TiO₂ Catalyst

CHEN Yi-Lin, LI Dan-Zhen, FU Xian-Zhi, LIU Ping

2004, 25(2):  342-344. 

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Pt/Pt⁴⁺-TiO₂ photocatalyst prepared by a modified sol-gel process was investigated by X-ray diffraction, UV-Vis diffuse reflectance spectra, X-ray photoelectron spectroscopy, time-resolved photoconductivity and terephthalic acid fluorescence probing. The photocatalytic activities of catalysts were evaluated by using ethylene oxidation studies under visible light irradiation(λ>450 nm) from 40 to 62 ℃. It is found that the platinum doping in titania caused significant absorption shift to the visible region and the surface recombination of photogenerated carriers was inhibited. The results show that ethylene was not converted on conventional TiO₂ while the conversion was 90% and the complete mineralization was achieved over Pt-Pt⁴⁺/TiO₂ at 62 ℃ in our experiment. Besides the exponential increase of thermalcatalytic activity, pure photocatalytic activity of the planitized sample enhanced linearly with the increase of temperature.

Hydrothermal Preparation of Highly-oriented ZnO Nanorod Array Films

GUO Min, DIAO Peng, CAI Sheng-Min

2004, 25(2):  345-347. 

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By using a simply and low-temperature hydrothermal method, ZnO nanorod array films with narrow size distribution and high orientation consistence were successfully prepared on ITO substrates, which were pre-treated with ZnO colloid solution. The obtained ZnO nanostructure was characterized by XRD and SEM. The results of characterization indicate that the nanorods are high-quality single crystals growing along (001) direction with a high consistent orientation perpendicular to the substrate. SEM images show that the nanorods have a very narrow size distribution of 20—50 nm with the average diameter about 40 nm. The room temperature photoluminescence of the as-prepared ZnO films exhibits a strong UV emission at about 390 nm and a weak emission at about 460 nm. The ease of fabricating high-quality ZnO nanorod arrays in large scales will greatly promote the fundamental research and practical applications of the ordered one-dimention ZnO structure in various fields of nanoscale science and technology.

In Vivo and Rapid Detection of the Malignancy Tumor of Oral Tissues Using Mid-FTIR Fiber Optics Spectroscopy

XU Yi-Zhuang, ZHANG Yuan-Fu, YANG Li-Min, PENG Xin, SUN Kai-Hua, LI Qing-Bo, ZHOU Wei-Jin, WU Hui-Zhong, YU Guang-Yan, LIU Zhi, WENG Shi-Fu, WANG Jing, ZHAO Ying, XU Duan-Fu, WU Jin-Guang

2004, 25(2):  348-350. 

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Our previous studies show that mid-FTIR spectroscopy can be used to distinguish malignant oral tissue from normal tissue under in vitro condition. Here, an in-situ FTIR spectroscopic measurement was performed to record FTIR spectra of normal and malignant oral tissues including salivary gland, tongue, parotid gland, submandibular gland etc. during clinical examination. The FTIR spectra of various oral tissues were acquired when an ATR probe linked to the FTIR spectrometer via mid-IR optical fibers was pressed on the tissues of the patients. For example, a patient(male, 76 years old) with tumor on the left parotid and the corresponding normal tissue on the right parotid were measured and obvious differences were observed. The spectral features of normal tissue and tumor are in good agreement with the criteria established in our previous work. (1) 1 389 cm^-1 band is quite strong in tumor, while the corresponding band in normal tissue is weaker than 1 452 cm^-1 band. (2) In normal tissue, 1 250 cm^-1 band is stronger, but the 1 250 cm^-1 band disappeared in the skin of malignant tissue. The above results demonstrate that in vivo FTIR spectra are in good agreement with our previous results obtained under in vitro condition. We believe that in vivo FTIR spectroscopy, providing the first-hand information concerning whether the suspected tissue is cancerous or not, is helpful for doctors in clinical activity.

Ti-V-based BCC Phase Hydrogen Storage Alloys with a High Capacity

YU Xue-Bin, WU Zhu

2004, 25(2):  351-353. 

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The hydrogen storage performance of single BCC phase Ti-V-based alloys was investigated. A hydrogen absorption capacity of 4.2% was achieved at 293 K at a modest pressure(3 MPa) for Ti-40V-10Cr-10Mn alloy. The effective hydrogen capacity of this alloy is 2.6% at 353 K. Moreover, the alloy exhibits a better activation property and flatter hydrogen absorption-desorption plateau. In order to meet different practical application needs, a series of Ti-V-based alloys with various PCT plateau pressures could be obtained by varying the element contents of the alloys, which opened the hope to bring Ti-V-based alloy into reaching the practical application for onboard hydrogen storage systems in fuel cell powered vehicles.

Alkylation of Benzene with Propene over SO₄^2-/ZrO₂-MCM-41 Catalyst

WEI Chang-Ping, WANG Wei-Dong, SHAO Jing, ZHEN Kai-Ji

2004, 25(2):  354-356. 

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Super acid catalyst SO_42-/ZrO₂ was introduced in pure silicone MCM-41 by macerating method and characterized by XRD, IR and Py-IR. The selectively catalytic gas phase flow reaction of benzene and propene over the catalysts was tested. The result show that the SO_2-4/ZrO₂-MCM-41(SZM-41) can be used as a catalyst for the title reaction and has a high catalytic activity under some conditions.

Correlation Between Oxidation-induced Crosslinking and Rheological Behavior of HDPE

WU Gang, ZHENG Qiang, JIANG Lei, SONG Yi-Hu

2004, 25(2):  357-360. 

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Studies on the dynamic viscoelastic properties of high-density polyethylene(HDPE) were carried out at 200 ℃ in the atmosphere of air, nitrogen, and in the case of blending with antioxidant B215 respectively. The results revealed that there existed specific character in dynamic rheological behavior corresponding to the conditions above. Especially, in a low frequency range the dynamic storage modulus(G') increased while the dynamic loss tangent(tanδ) decreased obviously in air atmosphere. For the HDPE samples exposed to air, compared with N₂ and the condition of blending with B215, the second plateau appeared in G'~ω curves in a low frequency range and the value of peak appeared in tanδ~ω curves decreased simultaneously, together with shifting of the peak in a higher frequency range, were attributed to the change of structure in HDPE because of the oxidation-induced crosslinking of HDPE.

Synthesis and Properties of the Hydrophilic Copolymer Support Containing Oxirane for Immobilized Penicillin Acylase

XUE Ping, LU Guan-Zhong, GUO Yang-Long, WANG Yun-Song

2004, 25(2):  361-365. 

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Oxirane groups can react with the amino groups of enzyme under mild conditions so that the enzyme molecules are immobilized on the copolymer support containing oxirane. A series of macroporous hydrophilic copolymers(GNM) containing oxirane were synthesized by inverse suspension polymerization with glycidyl methacrylate(GMA) as the reactive monomer, N-vinyl-2-pyrrolidone(NVP) as the hydrophilic comonomer, N,N′-methylene-bis-acrylamide(MBAA) as the crosslinking agent, and methanol and water as the porogenic agent and used as the support for the immobilization of penicillin G acylase(PA). The effects of the amount of the crosslinking agent on the structure properties and the apparent activity of immobilized enzyme were investigated. The specific surface area of GNM copolymer increased, its average pore diameter and pore volume decreased, and swelling degree in water increased and then decreased with increasing the amount of the crosslinking agent. The apparent activity of 625 U/g(dry weight) was obtained when the enzyme immobilized on GNM polymer [m(NVP)/m(GMA)=1/5, {w(MABB)=}40%] with a mean pore diameter of 16.5 nm, an oxirane group content of 0.906 mmol/g and swelling degree of 203% in water. The optimal pH value and temperature of the hydrolysis of penicillin G over the immobilized enzyme was 8.0 and 50 ℃, respectively. The immobilized enzyme was kept at 4 ℃ for 40 d, the change of the activity was not observed.The apparent activity of the immobilized enzyme reached a relatively steady value(about 601 U/g) after the immobilized enzyme was used for the hydrolysis of penicillin G for 3 times at 37 ℃. It was used continuously and repeatedly for 12 times, the activity was hardly changed.

Studies on Dispersion Copolymerization of St-AA-EGDMA for Preparing Monodisperse Micron-size Functional Microspheres

ZHANG Hong-Tao, LÜ Rui, CHEN Min

2004, 25(2):  366-371. 

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Dispersion copolymerization of styrene(St), acrylic acid(AA) as functional monomer and ethylene glycol dimethacrylate(EGDMA) as the crosslinking monomer was carried out in ethanol/water mixture as the media by using poly(N-vinylpyrrolidone)(PVP), 2,2-azo-bisisobutyronitrile(AIBN) as the stabilizer and initiator, respectively. Monodisperse micron-size crosslinked polystyrene microspheres-containing carboxyl were directly prepared by one-step method of dispersion copolymerization. Polymerization kinetics was researched and kinetics formula, R_p=k[I]^0.13([St]^1.87+[AA]^0.13+[EGDMA]^0.2)·({1+[PVP]^0.2)exp(-E/RT), was rendered. The effects of concentration of AA, EGDMA, PVP and solvent polarity on the carboxyl distribution were discussed in detail. The effects of concentration of AA and EGDMA on particle morphology, particle size and size distribution and carboxyl distribution were also researched.

Preparation, Third-order Nonlinear Optical Property and Optical Information Storage of Polyimide Attached with Azobenzene Chromophore Side-chain

SUN Jian-Ping, WU Hong-Cai, LI Bao-Ming, YING Zu-Jin

2004, 25(2):  372-375. 

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Using aniline and benzaldehyde as raw materials, p,p'-diaminotriphenylmethane(DTM) was synthesized. Co-condensation type poly(amic acid) was prepared by using p,p'-diaminotriphenylmethane as the co-diamine monomer and pyromellitic dianhydride(PMDA) as the the dianhydride monomer. And then the nonlinear optical polyimide(NLOPI) attached with azobenzene chromophore side-chain was synthesized by diazo coupling reaction of 4-nitrobenzenediazonium tetrafluoroborate to poly(amic acid) in 1-methyl-2-pyrrolidone(NMP) and imidization reaction at 250 ℃. The designed chemical structure of production can be proved in the infrared spectrum and ultraviolet-visible absorption spectrum. The NLOPI exhibits UV-Vis absorption of the azobenzene chromophore at the wavelength of about 330 nm and 490 nm. The third-order nonlinear optical property of NLOPI was studied by degenerate four-wave mixing(DFWM). Third-order nonlinear susceptibility of NLOPI is 3.28×10^-10 esu(4.58×10^-18 m²/W). It is indicated that NLOPI has strong optical information storage through DFWM. Forward pumping light(I_f) and detecting light(I_p) are prime writing light, however backward pumping light(I_b) is principal reading light. It is proved that optical information storage can be caused by photo-induced trans-cis isomerization of azobenzene.

Synthesis and Characterization of Poly(butylene terephthalate-co- cyclohexylene dimethylene terephthalate)-b-poly (ethylene glycol) Block Copolymers

ZHANG Yong, WU Chun-Hong, FENG Zeng-Guo, LIU Feng-Xiang, ZHANG Ai-Ying, WANG Lian-Cai

2004, 25(2):  376-381. 

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A series of poly(butylene terephthalate-co-cyclohexylene dimethylene terephthalate)-b-poly(ethylene glycol) block copolymers(PBCG) with aromatic moieties PCT molar fraction(x_PCT) varying from 10% to 60% were synthesized and characterized by means of GPC, NMR, thermal analysis and mechanical properties testing. The copolymers exhibit a good symmetric peak in GPC chromatograph with the number average molecular weight more than 3.5×10⁴ and polydispersity less than 1.70. Sequence distribution analysis reveals that the average sequence length of hard segment PBT decreases from 4.02 to 1.41, while that of PCT increases from 1.17 to 2.50 with the increase of x_PCT. The random distribution of the two hard segments is also confirmed in the same way. Microphase-separation structure was demonstrated for the appearance of two glass transition temperatures(T_g,s, T_g,h) and one melting point(T_m,h) belonging to the soft and hard segments, respectively. And the variation of average sequence length and the co-crystallization of two hard segments should be responsible for the minimum of melting point and crystallinity of hard segments at x_PCT being equal to about 20%. The higher thermal stability was justified for increasing decomposition temperature with ascending x_PCT from 10% to 30% in TGA thermograms as well. The mechanical properties testing shows that the lower crystallinity imparts the copolymer higher elongation, while the higher one improves the elastic modulus, tensile strength and yield strength.

Preparation and Properties of Physically Cross-linked Poly(vinyl alcohol)/ Hydroxy-terminated Polyamidoamine Dendrimer Hydrogels

WU Xu-Ye, HUANG Shi-Wen, ZHANG Jian-Tao, ZHUO Ren-Xi

2004, 25(2):  382-384. 

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Novel physically cross-linked hydrogels, composed of PVA and hydroxy-terminated polyamidoamine(PAMAM) dendrimer G6-OH, were prepared by cyclic freezing/thawing treatment of aqueous solutions containing PVA and G6-OH. FTIR analysis indicates that PAMAM dendrimer G6-OH was successfully introduced into PVA hydrogels. Higher contents of G6-OH in PVA/G6-OH hydrogels resulted in higher swelling ratios, and faster reswelling rates. With the increase of freezing/thawing cyclic times, the swelling ratios and reswelling rates of PVA/G6-OH hydrogels decreased, which is similar to that of physically cross-linked PVA hydrogel.

IR Studies on Conformation Changes of Poly(ethylene oxide) Thin Films

CHEN Zhou, WANG Zhen, YANG Rui, XIE Xu-Ming

2004, 25(2):  385-387. 

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The conformation changes in PEO thin films were studied by means of FTIR-ATR. The results showed that there were some pronounced intensity changes of some bands in IR spectra of PEO thin films when the film thickness was changed. With the decrease of the thickness of the PEO films, the amount of the gauche conformation relative to the trans conformation of PEO crystal increased. This conformation change indicates PEO chains prefer to assume the helical structure near the surface of the substrate, which should be resulted from the interactions between PEO chains and the substrate. This suggests the possibility for using thickness to adjust PEO chains conformation in the crystalline area.

Proton Conducting Composite Membranes from Sulfonated Polyether Ether Ketone and Phosphotungstic Acid

LI Lei, XU Li, WANG Yu-Xin

2004, 25(2):  388-390. 

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A novel inorganic-organic composite membrane based on sulfonated polyether ether ketone(SPEEK) with embedded phosphotungstic acid(PWA) for direct methanol fuel cells(DMFC) was prepared. IR spectra results indicate that PWA was kept in SPEEK matrix as the Keggin structure. From SEM micrograph, it could be found that the solid PWA were well mixed with SPEEK matrix and showed no agglomeration in the membrane. Proton conductivity of the PWA/SPEEK composite membrane is higher than that of pure SPEEK membrane, and is similar or superior to that of Nafion ^?115 membrane in the temperature range 80—110 ℃. Methanol permeability of the PWA/SPEEK membrane was considerably smaller than that of Nafion ^?115 membrane. Because of its high conductivity and low methanol permeability, the PWA/SPEEK membrane seems to be an excellent candidate for DMFC applications.

Studies on Sound Absorption Coefficient on Polymer Damping Materials

MENG Yan, YU Xiao-Qiang, LI Hong-Tu, WANG Jing-Yuan, YANG Song-Ru, TANG Xin-Yi, SUN Jia-Zhong

2004, 25(2):  391-393. 

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The sound absorption coefficients of PVC were measured at different frequencies and temperatures. The results show that the sound absorption coefficient of polymer as a function of the loss factor was detected when the sample′s thickness is fixed. And the polymer materials exhibit the special sound absorption frequencies. It is supposed that the damping polymer materials with a better sound absorption at a fixed frequency can be synthesized.

Studies on UV Transparent Characteristics of Carbon Nanotube Filled LDPE Films

DI Ze-Chao, LU Wei-Zhe, WANG Kun-Lin, LIANG Ji

2004, 25(2):  394-396. 

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The carbon nanotubes(CNTs) and two types of low density polyethylene(LDPE, DFDA7042 and EF7B) were melting blended and blown into films with thickness 10 μm. The ultraviolet(UV) transparent characteristics and the mechanical properties of the films were investigated. The UV transparency of the films can be reduced significantly when the content of CNTs was very low; the UV transparency of the DFDA7042 film filled with 0 01% CNTs and the EF7B film filled with 0 01% CNTs was decreased by 52.1% and 50.8%, respectively compared to the blank films. CNTs would agglomerate in the LDPE matrix with the CNTs content increasing, which lead to the increase of the UV transparency.