Table of Content

24 January 2004, Volume 25 Issue 1

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Articles

Inhibition of Influenza Virus Infections in MDCK Cells by Rare Earth Borotungstates Heteropoly Blues with Mixed Valence

LIU Jie, MEI Wen-Jie, LI An-Xing, TAN Cai-Ping, SHI Shuo, JI Liang-Nian

2004, 25(1):  1-6. 

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Transition} metal-substituted mixed-valence rare earth borotungsto-heteropoly blues, Ln₂H₃[BW₉^ⅥW₂^ⅤCo(H₂O)O₃₉]·nH₂O(Ln=La, Ce, Pr, Nd, Sm, Eu, Gd), were prepared and characterized by IR, UV, CV, TG-DTA, XPS and electrochemistry. The cell toxicity and antiviral activity of these rare earth borotungstate heteropoly blues were investigated on the inhibitory effect against influenza(A/H1N1/Jingfang/1/91, A/H₃N₂/Jingfang/30/95, B/Hufang/1/87) in MDCK cells, and the results suggest that these complexes exhibit an significantly inhibitory activity, which are comparable with those obtained from virazole, against influenza virus infection, and no cytotoxicity is shown on normal cells. The correlation(relation) between the structure of these complexes and their anti-virus activities was also discussed.

Synthesis and Structure Characterization of (EnH₂)₂Ge₂S₆

BAIYIN Meng-He, LIU Xin, JI Min, JIA Cui-Ying, AN Yong-Lin, WANG De-He

2004, 25(1):  7-10. 

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Solvothermal technique was used for the synthesis of (EnH₂)₂Ge₂S₆ and the crystal structure was determined by single crystal X-ray diffraction method. The compound comprises of isolated diborane-like Ge₂S_64- formed by edge-sharing of two tetrahedral GeS₄. The atoms in Ge₂S_64- are located in two orthogonal planes, two Ge atoms and bridging sulfur atoms are in one plane and terminal sulfurs and Ge in the other one. The compound belongs to the monoclinic system, space group P2(1)/n, with a=0.671 25(5)_nm, b=1.122 90(4)_nm, c=1.075 18(4)_nm, β=92.288(2)°, Z=2; V=0.809 77 nm³. DSC-TG studies show that the compound is stable below 200 ℃.

Synthesis of Spherical YBO₃∶Eu Phosphors by Spray Pyrolysis Method

WANG Lie-Song, LIN Jun, ZHOU Yong-Hui

2004, 25(1):  11-15. 

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Non-aggregated and spherical YBO₃∶Eu phosphor particles with a narrow size distribution(1—2 μm) were first prepared by a two-step spray pyrolysis process. The effects of PEG concentration on the phosphor morphology and emission intensity, the annealing temperature on the crystallinity, the precursor concentration on the particle size and the doping concentration of Eu³⁺ on the emission intensity were investigated, respectively. The phosphor particle size can be controlled by changing the concentrations of precursor and PEG. Solid and spherical phosphor particles with a size of 1—2 μm were obtained with a certain precursor concentration (0.07 mol/L) and PEG concentration (0.04 mol/L), and the aggregation between particles did not appear even after annealing at a high temperature. Higher or lower concentration of PEG makes the phosphor particles broken or hollow, which will low the emission intensity. The results of XRD indicate that the powders begin to crystallize at 700 ℃ and completely crystallized at 1 100 ℃, and the optimum concentration for Eu³⁺ was determined to be 10%(molar fraction) of Y³⁺ in YBO₃ host lattices.

A Novel Liquid-solid Isomorphous Substitution Route for Preparing Zeolite Ti-β

ZHOU Wei, CHUN Yuan, XU Qin-Hua, WANG Cheng, DONG Jia-Lu

2004, 25(1):  16-20. 

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A novel convenient method, liquid-solid isomorphous substitution(LSIS) of Ti(SO₄)₂, was used to post-synthesize titanium beta(Ti-β) zeolite in this paper. The prepared Ti-β zeolites were characterized by XRD, IR, Raman, UV-Vis, XPS, adsorption of hexane, as well as catalytic testing. Ti-β zeolite prepared from 30% Ti(SO₄)₂ showed good catalytic properties, while excessive usage of Ti(SO₄)₂ rendered an inferior catalyst. The results from Raman, UV-Vis and adsorption of hexane indicate that fewer extra-framework Ti species were formed on these modified samples. The presence of the strong absorption band around 220 nm in UV-Vis spectra and the appearance of the band around 960 cm^-1 in IR spectra demonstrate that the tetrahedrally coordinated Ti-atoms exist in the framework of Ti-containing zeolites. These Ti-β zeolites prepared by LSIS method were active in the epoxidation of olefin with H₂O₂, and the main products are the alcoholysis and hydrolysis product of the epoxide, due to the stronger acidic sites remained on the catalysts. The significantly higher activity can be achieved on these Ti-β zeolites in epoxidation of cyclohexene with respect to conventional TS-1 zeolite.

Crystalline Carbon Nitride Deposited by Glow Discharge in Liquid Phase

LI Chao, CAO Chuan-Bao, ZHU He-Sun, Lü Qiang, ZHANG Jia-Tao, XIANG Xu

2004, 25(1):  21-23. 

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A new electrodeposition system, with a thin nickel wire as the anode, was used to deposit the CN x thin film on Si(100) substrate from a dicyandiamide-saturated solution in acetonitrile at a high potential. During the experiment, when a certain high potential was applied, spark occurred between the Ni wire anode and the Si(100) substrate. The films were characterized by X-ray photoelectron spectroscopy(XPS), Fourier-transform infrared spectroscopy(FTIR), scaning electron microscopy(SEM) and X-ray diffraction(XRD). It was indicated that multiphase of α-C₃N₄, β-C₃N₄ and g-C₃N₄ was obtained in the films. This work is the first attempt to deposit carbon nitride material through a thin nickel wire anode and might provide a new route for preparing pure crystalline C₃N₄.

Luminescence Modulation of Porous Silicon-Zinc Sulfide Nanocomposite by in situ Synthesis of Zinc Sulfide

XING De-Song, SHI Jian-Xin, GONG Meng-Lian, PANG Qi

2004, 25(1):  24-26. 

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Porous silicon-zinc sulfide nanocomposite(PS-ZnS) was prepared by in situ synthesis of ZnS via a simple polyphase reaction on the base of nano-PS. The formation of the composite was confirmed by X-ray diffraction(XRD), field emission scanning electron microscopy(FE-SEM), energy dispersive spectroscopy(EDS) and photoluminescence(PL) measurements. Based on the XRD data and the Debye-Scherrer equation, the size of the formed ZnS particles both on the surface and in the holes of the PS was calculated to be nano-scaled, ca. 5—7 nm. FE-SEM observation showed agglomeration for the ZnS particles with an average crystallite size of 30—40 nm, and the hole diameter of the PS was below 100 nm. PL measurements and CIE diagram analysis for the PS-ZnS composite samples indicated that the emitted light color from the composites could be modulated and controlled by changing the annealing conditions, from orange to violet-blue, and finally, white-light emitter of the composite was obtained.

Hydrothermal Synthesis and Crystal Structure of Polyoxovanadate Linked by Transition Metal Complex Fragments [Co(o-phen)]V₂O₆·H₂O

WANG Shu-Tao, HOU Yu, WANG En-Bo, LI Yang-Guang, HU Chang-Wen

2004, 25(1):  27-29. 

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The hydrothermal reaction of NH₄VO₃, CoCl₂·6H₂O, o-phen and H₂O gave a novel two-dimensional layered polyoxovanadate, [Co(o-phen)]V₂O₆·H₂O, which was constructed from {V₂O₆} chains linked by Co(o-phen) complex fragments. [Co(o-phen)]V₂O₆·H₂O was characterized by IR, TG and single-crystal X-ray diffraction. It crystallizes in monoclinic space group P2(1)/c with a= 0.785 2(9)_nm, b=2.118 3(2)_nm, c=0.946 3(11)_nm, β=112.827(2)°, V=0.145 1(3)_nm³, D_c=2.074 g/cm³, Z=4, R₁=0.038 8, wR₂=0.094 1.

Automatic Continuously Amplification of Long Fragments DNA with Spiral Flow Through PCR Microchip

LIU Jin-Hua, YIN Xue-Feng, FANG Zhao-Lun

2004, 25(1):  30-34. 

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A spiral-channel flow-through PCR microchip reactor with 35 cycles, which reduced the dispersion and flow resistance of reaction solution, has been developed. A PCR amplification of a 6 012 bp-base pair fragment from λ-DNA was successfully performed on the chip in₂6 min, which is much faster than the reaction time(3 h) with conventional PCR. By transporting the solutions through the capillary instead of PTFE tubing, the dead volume of the sequential injection(SI) system was reduced from 14 to 0.30 μL. The SI system is capable of automatic manipulation of microliter samples in the PCR system, including continuous PCR amplification, autosampling and microchannel washing. Seven samples could be continuously amplified in 1 h and no cross-contamination between samples in serial treatments was observed. The standard deviations of the amplified fragment sizes and peaks area analyzed by a microfluidic chip-based capillary electrophoresis system, for replicates number 7, were 0.4% and 6.7%, respectively.

Studies on the Microwave-assisted Extraction of Efficacious Ingredients in Salvia Mltiorrhiza Bunge

CHEN Lei, YANG Yi, ZHANG Xin-Xiang, GUO Zhen-Ku

2004, 25(1):  35-38. 

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A microwave-assisted extraction procedure was developed for transhinone Ⅰ, transhinone ⅡA and cryptotranshinone in Chinese herbal medicine Salvia mltiorrhiza Bunge, using an obturated microwave-assisted extraction device with a pressure controlling part. The effects of the solvent consistence, solid/liquid ratio, the microwave radiation time and sample particles on the leached output was studied. Compared with Soxhlet extraction and ultrasonic extraction, microwave-assisted extraction is more efficient.

A Method for Analysis of Extracting Solution of Panax Notoginseng Using Near-infrared Spectroscopy and Support Vector Regression

QU Hai-Bin, LIU Xiao-Xuan, CHENG Yi-Yu

2004, 25(1):  39-43. 

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A new method for building near-infrared spectroscopy(NIRS) calibration model using support vector regression(SVR) was proposed. After NIRS data of the extracting solution of Panax notoginseng herb were processed with pretreatment and principal component analysis, NIRS calibration models of ginsenoside R_g1,R_b1, R_d and panax notoginseng saponins(PNS) were built by using SVR. The reference measurements of ginsenoside were performed by HPLC method for ginsenoside R_g1,R_b1, R_d and colourimetric method for PNS. The proposed method was compared with partial least square regression(PLSR) and radial-basis function neural network(RBFNN) modeling methods. The results showed that the predictive accuracy of NIR calibration models built by SVR was much better than that of the models built by PLSR and RBFNN. Therefore, the method could be applied to NIR analysis for extraction process of Chinese medicine.

Studies on Piezoelectric Insulin-C Peptide Micro-array Immunosensor

ZHANG Bo, FU Wei-Ling, MAO Qiong-Guo, ZHANG Xue, TANG Wan-Li, YU Fan

2004, 25(1):  44-49. 

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A new 2×5 type of piezoelectric insulin-C peptide micro-array immunosensor was developed for the determination of insulin and C peptide. The energy converters were 10 MHz AT-cut quartz crystals with gold-coated electrodes. The monoclonal antibodies of insulin and C peptide were immobilized onto the surfaces of crystals gold electrodes respectively, then piezoelectric insulin-C peptide micro-array immunosensor was constructed by 2×5 type of immobilization clamping apparatus. The effects of methods, work concentrations, the amount and coherence of immobilization of antibody and the response parameters of the micro-array immunosensor such as temperature, time-cost and specificity etc. were investigated. Under the optimized conditions, the experimental results showed piezoelectric immunosensor had good response to insulin and C peptide whose frequency shifts were linearly dependent on insulin concentration in the range of 2.5—160.0 mIU/L and C peptide concentration in the range of 0.375—12.0 ng/mL. The piezoelectric micro-array immunosensor were used to detect insulin and C peptide in serum, the analytical results given by this approach were in satisfactory agreement with those given by radiometric immunoassay(P>0 05), with correlation coefficients 0 92 and 0 94. The piezoelectric micro-array immunosensor for the determination of insulin and C peptide is of high sensitivity, high specificity, low density micro-array structure, high analysis speed, unnecessary labelling, simple operation, real-time detection and repeated use, etc.. It is suitable for detecting insulin and C peptide of serum in clinical laboratory.

Studies on the Chemical Modification and Its Mechanism of Acetylacetone in Low Temperature ETV-ICP-AES

WU Ying-Liang, HU Bin, JIANG Zu-Cheng

2004, 25(1):  50-52. 

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The vaporization and transport modes of Be and Cr(Ⅲ) from the graphite tube were studied by using the low temperature vaporization technique combined with ICP-AES. The main factors of influencing the formation of Be and Cr(Ⅲ) acetylacetonates were investigated. It was found that the Be and Cr(Ⅲ)} acetylacetonates were able to vaporize and introduce quantitatively into ICP with good thermal stability and volatility. The chelation reaction between the analyte and acetylacetone should be completed before the sample introduction to avoid the formation of refractory carbide and to eliminate the memory effect.

Nondestructive Quantitative Analysis of Paracetamol Tablet Medicines by NIR Spectroscopy

DOU Ying, QIU Fang-Ping, LIU Pei-Yi, REN Yu-Qiu, REN Yu-Lin

2004, 25(1):  53-55. 

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The application of artificial neural network(ANN) and near-infrared spectroscopy for pharmaceutical nondestructive quantitative analysis of Paracetamol was investigated. The artificial neural network patterns of Paracetamol tablet medicines, powder medicines, first derivative spectra and second derivative spectra were established, and they were compared each other. The uncertain specimens were predicted. The parameters affecting ANN were discussed. A new network evaluation criterion, i.e., the degree of approximation, was employed, and the predicted results were reliable.

Solid Phase Synthesis of N-2-Chlorobenzylbenzamide and Its Crystal Structure

LUO Jun-Tao, HUANG Wen-Qiang

2004, 25(1):  56-59. 

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The title compound was prepared by solid phase synthesis technique. Polystyryl sulfonyl chloride resin 1 was treated with 2-chlorobenzylamine in the presence of pyridine to yield polymer-supported N-2-chlorobenzyl sulfonamide 2. Resin 2 was acylated with benzoyl chloride catalyzed by pyridine to give N-2-chlorobenzyl-N-benzoyl sulfonamide resin 3. After the cleavage of resin 3 using TiCl₄/Zn/THF in a radical way, N-2-chlorobenzylbenzamide(4) was obtained in 92% overall yield. The crystal structure of N-2-chlorobenzylbenzamide was reported as follows: N-2-chlorobenzylbenzamide crystallizes in the monoclinic space group P2₁ with cell parameters: a=0.714 9(3)_nm, b=0.877 2(4)_nm, c=0.970 4(4)_nm; β=95.172(7)°. N-2-Chlorobenzylbenzamide has two kinds of intermolecular hydrogen bonds in the crystal.

Studies on the Helical Structure and Optical Rotation of Methyl Substituted Chiral Cyclic Ester Compounds

FENG Feng

2004, 25(1):  60-62. 

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Four cyclic esters(1—4) and four cyclic esters substituted by methyl(5—8) were synthesized and their values of optical rotation were determined by polarimeter. The relationships of their optical active behavior and helical structure were investigated with the Rules Finding out Helical Segment combining X-ray structure image and its model structure. The variation of optical rotation value was analyzed. The experimental results accord with the quantitative analysis. It is proved that the optical ratation of compound is determined by the net optical value of the molecule and the Rules Finding Out Helical Segment can be applied to the analysis of the chiral cyclic ester.

Culture of Primary Rat Hepatocytes on Porous Chitosan Scaffolds

LI Jie-Liang, PAN Ji-Lun, ZHANG Li-Guo, YU Yao-Ting

2004, 25(1):  63-66. 

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Chitosan is considered to be a very promising biopolymer for various biomedical uses because of its nontoxic and biocompatible properties. In this study, porous chitosan scaffolds were prepared by freezing and lyophilization of chitosan gel. Scaffolds were modified with water-soluble polyanionic alginate. These scaffolds were viewed via scanning electron microscopy. The scaffolds with mean pore sizes from 50 to 200 μm had a high porosity of about 90%. Because of their large surface-to-volume ratio and the three-dimensional structure, they were used as the substrate for hepatocytes culture. The cell attachment ratio was much higher than on monolayer membrane. On the porous scaffolds, hepatocytes exhibited a round cellular morphology with many microvilli evidences on the surfaces indicating healthy cells. Metabolic activities were evaluated in terms of albumin secretion and urea synthesis. It was found that hepatocytes cultured on the modified scaffolds showed an increase in albumin secretion in the first 4 days and exhibited more stable albumin secretion than those on monolayer membrane and non-modified scaffold. Therefore, the primary rat hepatocytes culture using these modified scaffolds would be beneficial to liver assist device.

Synthesis of Rhenium(Ⅰ) Bipyridyl and Ruthenium(Ⅱ) Tris-bipyridyl Photosensitive Dyes Used for Solar Cells

SUN Shi-Guo, PENG Xiao-Jun, XU Yong-Qian, GAO Yun-Ling, SUN Li-Cheng

2004, 25(1):  67-70. 

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There has been a growing effort to convert solar energy into electricity in recent years. In order to get a stable solar cell system and acquire a high incident photon-to-current conversion efficiency(IPCE), two novel rhenium(Ⅰ) bipyridyl and ruthenium(Ⅱ) tris-bipyridyl photosensitive dyes were synthesized, the ethoxycarbonyl group in the dyes could be employed for covalently linking to the surface of the nanostructured TiO₂. Their structures, photophysical and electrochemical properties were studied. The UV-Vis absorption maxima were 382 and 476 nm; emission maxima were 622 and 672 nm, respectively. The Re(Ⅰ/Ⅱ) oxidation potential is significantly positive than that of Ru(Ⅱ/Ⅲ) which provides a larger driving force for electron transfer. The results show that they both have proper redox potentials, enough stability and are suitable for being used as photosensitizers of solar cells.

Synthesis, Fugicidal Activity and Quantitative Structure-activity Relationships of Novel Flavanone Derivatives

YANG Guang-Fu, DING Yu, YANG Hua-Zheng, WU Xiao-Jun

2004, 25(1):  71-75. 

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Fourteen novel flavanone derivatives containing various substituents were designed and synthesized, whose structures were confirmed by ¹H NMR, MS and elemental analysis. The fungicidal IC₅₀ in vitro against rice blast disease of the title compounds were tested and the quantitative relationship between their structures and fungicidal activities was analyzed by using comparative molecular field analysis(CoMFA) and Hansch-Fujita approach. The results show that the hydrophobicity, polarity effect and the energy of the highest unoccupied orbital are very important for fungicidal activity. If the molecule was easy to polarize and had a lower LUMO energy, it would show a high fungicidal activity. Correlation results show that lgK is the most suitable parameter to describe the hydrophobicity of the title compounds compared to two other hydrophobic parameters, Σπand clgP. The results of 3D-QSAR analysis suggests that the introduction of steric bulk group onto the 2,3,4-position and small steric bulk onto the 6-position of B ring will be favorable to the activity of the compound. The CoMFA analyses about the electronic property requirement are consistent with those derived from the Hansch-Fujita approach.

Synthesis, Structure and Photo-physical Properties of Two Novel Compounds DMSSB and CSSB with Up-conversion Fluorescence

CAO Du-Xia, FANG Qi, WANG Dong, XUE Gang, YU Wen-Tao, LIU Zhi-Qiang, ZHOU Yu-Fang

2004, 25(1):  76-81. 

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Two novel organic compounds with benzothiazolyl as π electron acceptor, dimethylamino and carbazolyl respectively as π electron donor: DMSSB(trans, trans-2-{4-[4-(N,N-dimethylamino)styryl]styryl}-1,3-benzothiazole) and CSSB(trans, trans-2-{4-[(4-N-carbazolyl)styryl]styryl}-1,3-benzothiazole) were synthesized. The crystal structure of CSSB was determined by X-ray diffraction method. Pumped by 800 nm laser, DMSSB and CSSB respectively exhibited strong up-converted orange(λ_max=589 nm) and blue-green(λ_max=488 nm) fluorescence in THF, large two-photon absorption cross-section and large two-photon fluorescence emission cross-section. The photo-physical data in various solvents and theoretical calculation results indicate that benzothiazolyl is a good electron acceptor.

Enantioselective Synthesis of a Natural 8-O-4′ Neolignan Compound

CHEN Xiao-Chuan, REN Xin-Feng, PENG Kun, WU Tong-Xing, PAN Xin-Fu

2004, 25(1):  82-84. 

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An enantioselective synthesis approach to erythro 8-O-4′ neolignans was reported. In this route a chiral six-membered cyclic acetal was a key intermediate that was obtained from Sharpless AD reaction followed by change of acetals. Then the stereoselective coupling between the intermediate and phenols by Mitsunobu reaction formed the frame of 8-O-4′ lignans. A natural 8-O-4′ norneolignan was enantioselectively synthesized as a single isomer for the first time by the route.

Studies on the Aconitum Alkaloids in the Sini Concoction by Electrospray Ionization Mass Spectrometry

WANG Yong, SONG Feng-Rui, JIN Dong-Ming, LIU Zhi-Qiang, LIU Shu-Ying

2004, 25(1):  85-89. 

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Electrospray ionization mass spectrometry(ESI-MS) was used for the analysis of the aconitum alkaloids in the complex prescription of TCM, Sini concoction, which consists of prepared aconite roots, liquorice and dried ginger, without needing chromatographic separation. [M⁺H]+ are formed for aconitum alkaloids in the positive ion mode. Eighteen aconitum alkaloids including benzoylaconines, aconitines and lipo-alkaloids were found. Benzoylaconines were detected as the main aconitum alkaloids in Sini concoction.

Effect of Amounts of Urea on Mn-substituted Hexaaluminate Catalysts Prepared by Hydrothermal Synthesis

XU Jin-Guang, TIAN Zhi-Jian, WANG Jun-Wei, XU Yun-Peng, XU Zhu-Sheng, LIN Li-WU

2004, 25(1):  90-94. 

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Mn-substituted hexaaluminate catalysts were prepared by hydrothermal synthesis based on hydrolysis of urea. The effects of amounts of urea[n(Urea)/ n(M⁺), M⁺ is metal cation with a single charge] added on chemical composition, phase, pore structure and methane combustion activity of the LaMnAl₁₁O_19-α catalysts were investigated. When n(Urea)/n(M⁺)=1.0, Mn²⁺ ions did not precipitated completely and the activity of the catalyst for methane combustion was low. With n(Urea)/ n(M⁺) ratio increasing to 2.0, the activity of catalyst was increased due to more amounts of hexaaluminate phase and larger pore diameter in the catalyst. With increasing of n(Urea)/n(M⁺) ratio further more, the activity of catalyst was decreased because amounts of hexaaluminate phase in the catalyst were decreased and the pore diameter of the catalyst became smaller. The life test during 100 h the catalyst prepared with n(Urea)/n(M⁺)=2.0 was carried out and the results showed that the activity of the catalyst for methane combustion and the specific surface area of the catalyst were maintained during 100 h life test.

Kinetics and Mechanism of Oxidation of Butylene-glycol by Dihydroxy- diperiodatonickelate(Ⅳ) with Spectrophotometry in Alkaline Media

SHAN Jin-Huan, QIAN Jing, WANG Meng-Ge, SHEN Shi-Gang, SUN Han-Wen, WANG An-Zhou

2004, 25(1):  95-98. 

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The kinetics of oxidation of β-butylene-glycol(β-BG) and γ-butylene-glycol(γ-BG) by DPN in alkaline medium was studied with spectrophotometry in a temperature range of 25—40 ℃.The reaction was found to be pseudo-first order with respect to DPN and to be fractional order to β-BG and γ-BG. The rate increased with the increase of [OH^-] and decreased with the increase of [IO₄^-]. Adding salts did not affect the rate and no free radical was detected. A mechanism involving a pre-equilibrium of an adduct formation between MPN and BG was proposed. The activation parameters of the rate-determining step were calculated.

Surface Activity of Amphiphilic Derivatives of Carboxymethylchitosan

SUI Wei-Ping, JIANG Xiao-Jie, ZHAI Li-Min, CHEN Guo-Hua

2004, 25(1):  99-102. 

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A new type of amphiphilic derivatives of carboxymethylchitosan(CMCHS) was prepared by reaction of CMCHS with alkyl glycidol ether. The surface properties were studied by means of surface tension. It was found that for the same chitosan derivative, within some substitution degree(SD), the efficiency and effectiveness of the decreasing of surface tension increased with the increase of SD. For the similar SD of the same series of carboxymethylchitosan derivatives, the longer the amphiphilic group chain length, the more the surface activity. When the SD of the carboxymethylchitosan derivatives was high and the amphiphilic group chain length was not very long, two transitions points appeared in the surface tension vs. concentration curve, which means the possibilities of the formation of intramolecular micelle. These phenomena did not appear for the derivatives with less SD and long amphiphilic group chain length.

Stability, Kinetics of Acid Decomposition of Cu(Ⅱ) Complexes of Novel Polyamide-polyamino Ligand

GUO Yan-He, GAO Dong-Zhao, LIN Hai, GE Qing-Chun, LIN Hua-Kuan, ZHU Shou-Rong

2004, 25(1):  103-107. 

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A polyamide polyamino ligand was synthesized. The stability constants of its copper (Ⅱ) complexes at 5, 10, 15 and 25 ℃ were determined. The standard molar entropy of formation ΔS_m⁰ and standard molar enthalpy of formation ΔH_m⁰ were obtained and used to discuss the effect of temperature on the stability of the complexes. The acid decomposition of CuL assisted by 0.04—2.34 mol/L(I= 2.34 mol/L NaCl) hydrochloride was investigated by using stopped-flow technique. The mechanism was given and the activation energy E_a, standard molar entropy of activation Δ^≠S_m⁰ and standard molar enthalpy of activation Δ^≠H_m⁰ of the rate-determining step were calculated.

Dispertion of ZnO to Ag in Ag/SiO₂ Catalyst and Its Effect on the Stability of Indole Synthesis

SHI Lei, SUN Ren-An, CAI Tian-Xi, WANG Xin-Ping

2004, 25(1):  108-111. 

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Indole, which is an important raw organic material and fine chemical product, has many uses in the fields of industry, agriculture and medicine. There are many known methods to produce indole. One of the most promising routes, from an economic point of view, seems to be the direct catalytic synthesis from aniline and ethylene glycol. For the reaction, Ag/SiO₂ catalyst exhibits very high activity. However the activity of Ag/SiO₂ catalyst declined with increase of time on stream in the reaction. In order to improve the stability of the catalyst ZnO promoter was doped into Ag/SiO₂ catalyst. Cu/SiO₂-ZnO catalysts were prepared by separative impregnation method. It was found that ZnO could enhance the stability of the catalyst greatly. It was firstly obtained from the characterization of XRD and TEM that ZnO could efficiently improve the dispersion of silver on the support and inhibit the sintering of silver crystallite during the reaction process. ZnO is a structure promoter.

Field Ionization of N₂ Molecule in Strong Laser Field

GAO Li-Rong, WANG Wei, WANG Su-Fan, KONG Fan-Ao

2004, 25(1):  112-115. 

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The field-assisted ionization of N₂ molecules in strong laser pulse was investigated. The theoretical ionization probabilities and the apparent ionization efficiencies with different angles are studied. The potential surfaces of N₂⁺ ions along different orientations were calculated by the ab initio method. The predicted ionization probabilities were obtained with the computation of tunneling efficiency by using the transfer matrix method. The probabilities were modified by the laser spatial and temporal corrections. The results agree with the observations in an experiment with a 800 nm and 70 fs laser. The yield dependences of laser intensity and of polarization plane are coincident with the theoretical predictions.

Calculations of Solvation Free Energies of NH₂^-, NH₃ and NH₄⁺ by Using the Discrete-continuum Model

CAO Zhi-Ji, WANG Chao-Jie, TAN Kai, LIN Meng-Hai, ZHANG Qian-Er

2004, 25(1):  116-119. 

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The solvation free energies of NH₂^-, NH₃, and NH₄⁺ in aqueous solution were calculated by means of a mixed discrete-continuum model, in which the solute and a limited number of solvent molecules were treated quantum chemically and the remaining solvent was simulated by the polarizable continuum model(PCM) method. The numbers of water molecules hydrogen-bonding directly with NH₂^-, NH₃, and NH₄⁺ are predicted to be 2, 4, and 4 respectively at the HF level. By comparing with the results obtained with the PCM method, our results show that because specific solute-solvent interactions are described at the quantum level and long-range interactions are introduced through a continuum model, the discrete-continuum model could simulate the solvation effects more accurately than the continuum model, especially in case where the solvent and the solute are strongly bound. The predicted solvation free energies for NH₂^- and NH₄⁺ are in good agreement with available experimental data. Due to the explicit consideration of specific solute-solvent interactions, the electron correlation effect is significant in the discrete-continuum model. Furthermore, from the gas phase to the solution, the large changes of geometries of hydrated solutes caused by the continuum field suggest that the geometry reoptimization in the solvent is necessary. In the discrete-continuum model, the geometries of hydrated ions closer to the real case would lead more accurate solvation free energies.

Theoretical Study on the Interconversion of α-Monosubstituted Cyclododecanone Conformations

LU Hui-Zhe, WANG Ming-An, WANG Dao-Quan

2004, 25(1):  120-123. 

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Under the CVFF force field and in DMSO, the conformations of α-monosubstituted cyclododecanones were studied by molecular dynamics at room temperature. The results show that the ring skeleton of the preferred conformation is [3333], with the carbonyl group being present in the C2 position, which is consistent with the experimental results. The interconversion between α-corner-syn-[3333]-2-one and α-side-exo-[3333]-2-one was analyzed by using dynamics mimesis method. The calculated results show that their interconversion paths are consistent basically, the preferred conformation is α-side-exo-[3333]-2-one and the interconversion energy barrier is increased along with the increase of the volume augmentation of the substituent groups. For α-chloro- and bromo-cyclododecanones, the maximum barriers are 43.9 and 44.3 kJ/mol, respectively, and the corresponding conformation is α-side-exo-[31233]-2-one. For α-alkylcyclododecanones, the maximum barrier is as high as 53.9 kJ/mol, and the corresponding conformation is α-side-exo-[31233]-2-one. While α-amino- and hydroxy-cyclododecacones, the conformation of the maximum energy is α-side-exo-[31323]-1-one, and α-phenylthio- and benzyl-cyclododecanones, apart from {α-side-}exo-[3333]-2-one conformation, the another stable conformation is α-side-exo-[4233]-3-one instead of α-corner-syn-[3333]-2-one.

Ab initio Studies on the Structures of the Hydrogen-bond Clusters C₅H₁₀NH(NH₃)_n(n=1—3)

SHI Tu-Jin, WANG Xu, TIAN Zhi-Xin, ZHU Qi-He

2004, 25(1):  124-127. 

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The equilibrium geometrical structures of hydrogen-bond clusters C₅H₁₀NH(NH₃)_n(n=1—3) were studied by ab initio MO theory with RHF/6-31G(d) basis set level. The calculated results show that the most stable structures of C₅H₁₀NH(NH₃)_n are one linear hydrogen-bonding, three-cyclic and four-cyclic structures for n=1, 2, 3, respectively. At MP2/6-31G(d)//B3LYP/6-31G(d) level, the MO population analysis of the most stable configurations C₅H₁₀NH(NH₃)_n(Ⅰ)(n=1—3) has been employed, and the corresponding occupied molecular orbitals have been assigned. Their calculated vertical ionization potentials(P_Ⅵ) show that the formation of hydrogen bonds causes the P_Ⅵ values to decrease.

Electrochemical Properties of LiMn_2-xCr_xO₄ as Cathode Materials of Lithium Ionic Batteries

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

2004, 25(1):  128-130. 

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To improve the specific of lithium ion batterise, main effort should be directed toward the synthesis of new positive electrode materials, i.e.. various lithiated oxide that could reversibly intercalate one Li atom per 3d-metal atom at about 4 V %versus% Li. Spinel lithium manganese oxide(LiMn₂O₄) attracted interest because of its economical and environmental advantages compared to other lithiated transition metal oxide such as lithium cobalt oxide(LiCoO₂) or lithium nickel oxide(LiNiO₂). However, efforts to substitute LiMn₂O₄ for LiCoO₂, in commercial Li-ion batteries have not been successful due to the rapid capacity fade upon cycling. This capacity fading has been suggested to be due to spinel dissolution, the Jahn-Teller effect and lattice instability. In the paper, doped LiMn_2-xCr_xO₄ compounds(0<x≤0.2) were synthesized. Though LiMn_2-xCr_xO₄ has a lower specific discharge capacity than that of LiMn₂O₄, it show the best cycle performance, the improvement of cycle performance is attributed to the stabilization of the spinel structure.

Application of Pt-Al₂O₃ Catalyst in Selective Catalytic Reduction of Nitrogen Oxide by Propene

LI Jun-Hua, HAO Ji-Ming, FU Li-Xin, ZHU Tian-Le, CHEN Ling-Lin, CUI Xiang-Yu, LIU Zhi-Ming

2004, 25(1):  131-135. 

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Pt-Al₂O₃ is an excellent catalyst for selective catalytic reduction nitrogen oxide at a lower temperature in the presence of oxygen. A series of Pt-Al₂O₃ catalysts with various platinium loadinds were prepared by the sol-gel(SG) and impregnation(IM) methods and the selective catalytic reduction activity of NO with propene(C₃H₆) as the reductant in the presence of excess oxygen was investigated in a fixed-bed microreactor. The results show that Pt-Al₂O₃ has a high activity. Based on the preparation method used in this paper, the optimal Pt loading in mass fraction is 0.35% for IM and 2% for SG respectively; the relationships between the activities over these catalysts and the reaction temperature and the concentrations of reactants and the operation condition were studied respectively. The increase of the C₃H₆ concentration and O₂ concentration in a certain range both promoted the reduction of NO, the optimal oxygen mass fraction is about 8%. The presence of 0.009% SO₂ decreases the catalytic activity, but the ability of resistance SO₂ of 2%Pt-Al₂O₃(SG) is better than 0.35% Pt-Al₂O₃(IM), 10% water present in the feed can enhance the catalytic activity above 250 ℃, and promoted the selective catalytic reduction of NO_x over a wide window(200—450 ℃).

Research of Selective Catalystic Reduction of NO with Propene over Catalyst Cu/Al₂O₃ in Excess Oxygen

ZHANG Chang-Bin, HE Hong, YU Yun-Bo, ZHANG Run-Duo

2004, 25(1):  136-139. 

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The selective catalytic reduction (SCR) of NO with propylene was investigated over Cu/Al₂O₃ catalyst by using fixed-bed reactor and in situ FTIR and compared with Ag/Al₂O₃ which has a relative high activity in C₃H₆-SCR of NO. The highest conversion of NO is only 40% at about 650 K, when the catalyst was exposed to a gas mixture of NO/C₃H₆/O₂/N₂=0.08%/0.171 4%/10%/balance with W/F=0.018 g·s/mL. Surface R—NO₂ and R—ONO species, which were observed on Ag/Al₂O₃ catalyst as the precursor of —NCO species, can hardly be found on Cu/Al₂O₃ catalyst surface in FTIR spectra under the same condition. This results in the low activity of Cu/Al₂O₃ catalyst for NO reduction. Through dynamic FTIR experiment, it was found that NO₃^- species, which are dominant surface species over Cu/Al₂O₃ catalyst, have a low activity with C₃H₆, so that the reaction producing R—NO₂ and R—ONO is very difficult to take place.

Criterion for Quantities of Surfactants Used in the Emulsifications

WANG Hai-Bo, LI Yan-Mei, LIU De-Shan

2004, 25(1):  140-143. 

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From the detailed investigation on the quantities of surfactants used in the emulsification of the systems oil/water/surfactant, it can be seen that the exceeding amount of surfactant added in the system was not only useless to the emulsification but also harmful to the stability of the emulsion. There was a limit of the quantity of surfactant used in the emulsification. This limit corresponds CMC (CMC_w + CMC_O). CMC is the criterion for the determination of the quantity of surfactant used in the emulsification.

Studies on the SERS-Active Optic Fiber Probe

XU Wei-Qing, XU Shu-Ping, HU Bing, WANG Kui-Xiang, ZHAO Bing, XIE Yu-Tao, FAN Yu-Guo

2004, 25(1):  144-147. 

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Surface-enhanced Raman scattering(SERS)-active optic fiber probe was fabricated with single optic fiber which modified the surface of the coned-shape fiber tip by two methods, vacuum deposited silver island and self-assemblied silver colloid. The fiber was used for both transporting the exciting laser radiation and collecting Raman scattering from the molecules absorbed onto the SERS-active substrates. Several molecules were selected to be analyzed and the molar detection limit reached 10^-9 mol/L. The SERS-active optic fiber probes were used for on line or in situ detection.

Studies on Electrochemical Generation System of Superoxide Free Radical

WEI Ying-Liang, WANG Ya-Zhen, HU Sheng-Shui

2004, 25(1):  148-150. 

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A mercury-free solid electrode system for the electrochemical generation of O ·- 2 was described. The effects of pH, the amount of the surfactant and electrode materials on the reduction of O₂ were investigated. The electrogeneration of O ·- 2 was only obtained at the Pt electrode in this medium system. The different electrochemical behaviour of O₂ at Pt electrode and Au electrode were explained in terms of the different adsorptions of DSAB, which was confirmed by quartz crystal microbalance(QCM). The frequency responses for the reduction of O₂ at Pt electrode and Au electrodes were compared by electrochemical quartz crystal microbalance(EQCM), suggesting that the electrogenerated O ·- 2 was adsorbed on the surface of the Pt electrode. The one-electron reduction of oxygen in this system was also confirmed by using chronocoulometry. The scavenging activities of two kinds of antioxidants(ascorbic acid and cysteine) were examined and compared.

A New Method Based on Ion Chromatography Technology for the Speedy Determination and Analysis in Organic Electrosynthesis

CHEN Sheng-Pei, HUANG Tao, ZHANG Qi, HUANG Wei-Xiong, SUN Shi-Gang

2004, 25(1):  151-153. 

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Based on ion chromatography technology, we have developed a new method that combines ion chromatography with a conductivity detector to separate and determine the substances of oxalic acid and glyoxalic acid, which are the main substances in the electrosynthesis of glyoxalic acid. The experimental results demonstrate that the detection sensitivity is ahead of 10^-6 grade, the cofficient of variation of retention time, the height of peak and the area of peak outperform 1%. All the recoveries of the detected substances are ranged between 98% and 102%. The method exhibits advantages of high selectivity, sensitivity, speediness and simple equipment. Furthermore, simultaneous determination of a mixture of several substances can be carried out by the method. We have demonstrated in the current paper that the ion chromatography is a speedy, effective, new detection method, which may be used to determine the substances existing in the electrosynthesis process of glyoxalic acid.

Photo-electric Conversion Properties of Oligo-thiophene Carboxylic Acid Sensitized Porous TiO₂ Films

LUO Zhen, TAN Shu-Xin, ZHAI Jin, FANG Hong-Juan, LI Yu-Liang, JIANG Lei, ZHU Dao-Ben

2004, 25(1):  154-156. 

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TiO₂ films with nano-porous structures were obtained by adding the poly-ethylene glycol(PEG) in the TiO₂ colloid. Then the as-prepared films were sensitized by the trithiophene carboxylic diacid(TTDA), pentathiophene carboxylic diacid(PTDA), N3[Ru(Ⅱ)L₂(SCN)₂, L=2,2′-bipyridyl-4,4′-dicarboxylate] dye and the mixture of PTDA and N3 dye, respectively. After fabricating the films into devices, the I-V curves were determined and their photovoltaic properties were studied. The results show that the porous TiO₂ films can be sensitized by both TTDA and PTDA effectively, while the film sensitized by the mixture of PTDA and N3 dye has a maximum photo-electric conversion efficiency.

Control of Thermally Induced Pattern Formation in Bilayer Metal/Polymer Films

ZHUANG Ke, XIAO Ke, WANG Guo-Jie, JIANG Lei

2004, 25(1):  157-158. 

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We described the appearance of complex, patterned structures induced by the buckling of metal thin films owing to thermal contraction on a polymer substrate. Polystyrene(PS) films with thickness of 100 μm were casted onto a glass substrate, and the Pt thin films with thickness of 30 nm were deposited onto the polymer surface. The sample films were heated above the glass transition temperature of PS. After cooling to ambient temperature, the disordered wrinkles generated over the whole surface. When we ablated the top metal thin film by laser before heating the polymer, the disordered bucking wrinkles would transfer into ordered ridges pattern. This patterning process is arresting and potentially useful to fabricate optical devices such as diffraction gratings and optical sensors.

Synthesis of BaC₂O₄ Crystals with Novel Morphologies in the Presence of a Double-hydrophilic Block Copolymer

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

2004, 25(1):  159-161. 

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The crystallization of barium oxalate in the presence of a double-hydrophilic block copolymer poly(ethylene glycol)-block-poly(methacrylic acid) (PEG-b-PMAA) was investigated. Barium oxalate crystals with a complex form, such as fan-like aggregates consisting of rod-like BaC₂O₄·H₂O crystals and spherical aggregates consisting of flake-like BaC₂O₄·3.5H₂O crystals were readily produced in aqueous solutions of PEG-b-PMMA. This result may provide an effective method for controlling the morphology and polymorph of inorganic crystals.

Preparation and in Vitro Release of Rifampin Microspheres Encapsulated in Biodegradable Polyesters

YANG Ya-Nan, LOU Ling, LIANG Qi-Zhi, CHEN Xue-Si, JING Xia-Bin

2004, 25(1):  162-165. 

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Microspheres containing antiphthisic drug Rifampin were prepared from poly(lactide-co-glycolide) (PLGA) as carrier by emulsion and solvent evaporation method. The conditions of the microsphere preparation such as the drug/carrier molar ratio, the volume ratio of organic solvent to water, PLGA concentration in organic solvent, speed of emulsification, kind of stabilizer, relative molecular weight of {PLGA}, LLA/GA mass ratio were discussed. The surface morphology of the microspheres in original and degraded states was observed by SEM. The mean diameter and drug content of microspheres were examined, and the drug release %in vitro% was evaluated. The morphology of the microspheres prepared from {PLGA} and by 1% gelatin as the stabilizer was integral with 10—30 μm diameter range, 24.3% average drug content, 42—84 d drug-release time. The drug-release kinetics with zero order satisfies the requirements of controlled drug-release.

Studies on the Second Aggregation Behavior of Primary Aggregates from BAB Triblock Copolymers with a Hydrophilic Middle Block A in Aqueous Media

YUAN Jian-Jun, YANG Zi-Gang, CHENG Shi-Yuan, JIANG Lei, FENG Lin-Xian, FAN Zhi-Qiang

2004, 25(1):  166-169. 

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The second aggregation behavior of spherical micelles, spherical vesicles and worm-like micelles made from PS₄₃-b-PEO₄₅-b-PS₄₃ and PS₃₉-b-P4VP₉₈-b-PS₃₉ triblock copolymers was investigated by conventional Transmission Electron Microscope(TEM) and Atomic Force Microscope(AFM) techniques. It was observed that the second aggregation behaved the different complexity for different primary aggregates. For the symmetrical primary aggregates, such as spherical micelles and vesicles, the second aggregates displayed a symmetrical sphere. In contrast, for the unsymmerical worm-like primary micelles, the second aggregation tended to have an unsymmetrical shape. The BAB chain architecture was molecularly suggested to be responsible for the second aggregation.

Studies on a Carbosilane Liquid Crystalline Dendrimer of the Third Generation Containing 108 4-Hexyloxyazobenzene Mesogenic Groups in Periphery

ZHANG Qi-Zhen, YIN Xiao-Ying, WANG Da-Qing, LI Guang, JI Yi-Ping, ZHAO Xiao-Guang

2004, 25(1):  170-173. 

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The divergent synthesis of a new carbosilane liquid crystalline(LC) dendrimer of the third generation(D3) was discribed. One hundred and eight 4-hexyloxyazobenzene groups were used as mesogenic fragments and attached in periphery and four carbosilane as the core. The structure and properties of D3 were characterized by elemental analysis, ¹H NMR, MALDI-TOF-MS, IR, UV-Vis, polarizing optical micrograph, DSC and WAXD. D3 is a nematic liquid crystal, which is the same as M3.The mesomorphic behaviour of the dendrimer depends on that of the mesogenic units. The phase behavior of D3 is K79N136I132N. The melting point of D3 is 19 ℃ lower than that of M3, and the clearing point of D3 is 16 ℃ higher than that of M3 and the mesophase region of D3 is 35 ℃ wider than that of M3.

Synthesis of Hyperbranched Polystyrene and Its Fullerene End-capped Derivatives with Multifunctional Atom Transfer Radical Polymerization Initiator

YANG Jun-Wei, WANG Chang-Chun, MING Wei-Hua

2004, 25(1):  174-178. 

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A novel multifunctional ATRP initiator was synthesized by esterfication of a hyperbranched polyester Z5[from pentaerythritol and 2,2-bis(hydroxymethyl)propionic acid]. The macroinitiator contained approximately 19 initiating sites per molecule. It was used for the ATRP of styrene mediated by CuCl and N,N,N,N",N"-pentamethyldiethylenetriamine(PMDETA) in cyclohexanone at 100 ℃. The molar ratio of monomer to initiator was 100/1, 200/1, 300/1, respectively. Through hydrolysis of hyperbranched polymer, the arm chain length of the hyperbranched polystyrene was detected by GPC, the results showed that ATRP process under these conditions was well controlled. The hyperbranched PS was further reacted with sodium azide in dimethyl formamide at room temperature to yield an azide end-functional hyperbranched polymer. Then a covalently bonded C₆₀-hyperbranched polymeric derivative was achieved by reacting C₆₀ with the sodium azide end-capped hyperbranched polymer in 1,2-dichlobenzene solution at 130 ℃. In the hyperbranched polymeric derivatives, the mass fraction of the fullerene was about 1%—2.5%.

Monte Carlo Study on Conformation Properties of Tail-like Chain of Block Copolymer

HUANG Jian-Hua, JIANG Wen-Hua, HAN Shi-Jun

2004, 25(1):  179-183. 

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The conformation properties and the spatial segment distribution of AB tail-like block copolymer are studied by means of dynamic Monte Carlo simulations based on the Metropolis method. The chain is self-avoiding on the simple cubic lattice, and the flat surface is located at z=0. An attractive energy -ε(ε>0) is assumed between segment B and the flat surface when segment B is at z=1. It is found that the chain dimension, shape and spatial segment distribution are dependent on the attraction energy -ε. At small ε, the sub-chain A contracts at first, while with increasing ε farther, the sub-chain B extends along the surface. In conclusion, we find that both the mean-square radius of gyration 〈S²〉 and the mean asphericity parameter 〈A〉 drop firstly and then go up with the increase of the energy ε. The spatial segment distribution also shows that both the segments A and B shift to the surface with increasing ε. At large ε, roughly all segments B are at the first layer z=1. The dependence of the conformation properties on the proportion of segment B is also investigated. With the increase of the attractive segment B, the variation of conformation properties with the energy ε becomes much more obvious.

Preparation of PS/PAN Self-compatibility Alloy via Concentrated Emulsion Polymerization and Self-compatibilization Mechanism

DU Zhong-Jie, ZHANG Chen, LI Hang-Quan

2004, 25(1):  184-187. 

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A novel self-compatibilization mechanism of concentrated emulsion polymerization was proposed. A kind of pseudo-block copolymer was generated directly on the interfaces of different droplets constituting the compatibilzers of polystyrene and polyacrylonitrile. The self-compatibility alloy was investigated by elemental analysis, Fourier transform infra-red spectrum(FTIR), scanning electron microscopy(SEM) and transmission electron microscopy(TEM). The results show that the higher the conversion of partial polymerization is, the better the compatibilization is. It can be concluded that the compatibilization was mainly influenced by the dispersion of monomers between different droplets of styrene and acrylonitrile concentrated emulsions, and the conversion of 9.0% was the benefit for the compatibilization.

A Bioinspired Phospholipid Polymer as Drug-laden Coating for Biomedical Device

XU Jian-Ping, JI Jian, CHEN Wei-Dong, FAN De-Zeng, SUN Fu-Yu, SHEN Jia-Cong

2004, 25(1):  188-190. 

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A novel bioinspired phospholipid copolymer was synthesized by the free radical polymerization of poly-2-methacryloyloxyethylphosphorylcholine(MPC), stearyl methacrylate(SMA), hydroxypropyl methacrylate(HPMA) and trimethoxysilylpropyl methacrylate(TSMA). A stable cross-linked coating was obtained via dip-coating, followed by curing at 70 ℃ for 9 h. Contact angle results indicate the coating surface rearrange to get a more hydrophilic surface on the polymer/water interface. The membrane mimic phosphorylcholine coating surface can resist the platelet adhesion and prolong plasma recalcification time significantly. Rhodamine S was used as model drugs to prepare drug-containing coating under the same conditions. Drug-releasing curves fall into Fickian release mechanism and there exists an efficient releasing-amount of the drug until 60 h.

Isothermal Crystallization Kinetics of iPP During Self-nucleation Process

WANG Song, YANG De-Cai

2004, 25(1):  191-193. 

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In this paper, the isothermal crystallization kinetics of polypropylene(iPP) during self-nucleation was studied by means of differential scanning calorimetry(DSC). The iPP was melted at 438 K and then isothermally crystallized in the range of temperature between 421 and 425 K. The mechanism of nucleation and growth of iPP was discussed. The Avrami equation was applied to analyzing the process of isothermal crystallization of iPP from the melt. The average value of Avrami exponent is n=3.01, suggesting that the primary crystallization maybe corresponds to three-dimensional spherulitic growth.The K_g value obtained from Lauritzen-Hoffman equation is 1.128×10⁵ K², which suggests that crystallization species should be regime Ⅱ. The decrease of crystallization active energy and chain folding work indicates that the self-nucleation can greatly promote the overall crystallization of iPP.

A Novel Chiral Conjugated Polymer Whose Chiral Property Has Different Responses with Different Metal Ions

BIAN Zheng, HE Ya-Bing, GAO Lian-Xun

2004, 25(1):  194-196. 

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A novel chiral conjugated polymer with chiral 1,1-binaphthyl and 2,2-bipyridyl units was prepared. The ion responsive properties of the polymer were measured in tetrahydrogenfuran by using absorption, emission spectra and optical rotation. The results show that absorption, emission spectra and optical rotation of the polymer solutions have different responses with interactions of different transition metal ions. The mechanism is that different changes of electrical and steric effects of the polymer can cause different changes of the properties of the polymer when interacting with different transition metal ions. The novel chiral polymer could be used for metal ion sensing.

UV Photoaging of Polyamide 6/Montmorillonite Nanocomposite

QIN Huai-Li, ZHANG Shi-Min, YANG Ming-Shu, SHEN De-Yan

2004, 25(1):  197-198. 

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Photo-oxidative degradation is critical to polymer materials. A UV photo-oxidation study on polyamide 6/montmorillonite nanocomposite was carried out by FTIR technique. Through the comparison of the infrared spectra of PA6 and PA6/MMT nanocomposite during different times of UV irradiation, it is indicated that the rate of photo-oxidation of PA6/MMT nanocomposite is faster than that of PA6.