Table of Content

24 May 2004, Volume 25 Issue 5

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Articles

Preparation of Lead Nanowires and Nanoparticles by Solution-based Method

XU Jian, LI Ya-Dong

2004, 25(5):  595-597. 

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A solution-based method was developed to obtain Pb nanowires in diameters of 70—120 nm and lengths up to~40 μm. Pb nanoparticles in diameter of 10—100 nm were also received under specific conditions. The products were characterized by XRD, SEM, and TEM. Based on the morphology and size evolution of products as varying reaction temperature, reactant concentration, as well as reaction time, the growth mechanism for Pb nanowires was suggested. Different reductants, such as diethyl glycol and hydrazine hydrate, were also compared.

Effects of Hydrothermal Synthetic Conditions on Co₃O₄ Cubes Morphologies

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

2004, 25(5):  797-801. 

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As a continued part of our research endeavor in the synthesis of Co₃O₄ with different morphologies by hydrothermal treatment followed by decomposition, the effects of hydrothermal synthetic conditions, such asthe starting concentration of Co(NO₃)₂ solution, pH of the suspension, hydrothermal temperature, holding time and the stocking mode, on the Co₃O₄ cubes were reported in this paper. The results of XRD, TEM and IR were used to monitor the procedures of hydrothermal treatment. The cube size increased with the increasing of the acidity of solution, but decreased at a higher temperature. Prolonging the treating time helped the growth of the Co₃O₄ cubes. Moreover, the phase transformation and mechanism of Co₃O₄ spinel formation during the hydrothermal synthetic process were also discussed.

Modulation of Urinary Macromolecules Induced by DPPC Monolayers on Morphology and Crystal Face of Calcium Oxalate Crystals

OUYANG Jian-Ming, DENG Sui-Ping, ZHONG Jiu-Ping

2004, 25(5):  802-805. 

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The effect of urinary macromolecules such as chondroitin sulfate A(C₄S), chondroitin sulfate C(C₆S) and serum albumin(SA) on urinary crystal calcium oxalate grown beneath dipalmitoylphosphatidylcholine (DPPC) monolayer was investigated by using scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and Fourier transform infrared analysis(FTIR). Only the calcium oxalate monohydrate (COM) was nucleated and grown beneath the monolayer with the (101) face oriented preferentially towards the monolayer interface. On the monolayer in the absence of additives, the tri-dimensional prismy COM crystals precipitated. However, the (101) face of COM was doubly strengthened and the other faces were weakened in the presence of urinary macromolecule inhibitors. This leads to the formation of two-dimensional plate-like COM crystals. The result is attributed to the interaction between the positively charged calcium-rich (101) face of COM with the negative-charged headgroups of the monolayer and the negatively charged macromolecules. All the three additives can inhibit the growth of COM crystals.

Synthesis,Structure and Dielectric Properties of New Niobates Ba₅LnZnNb₉O₃₀(Ln=Y,La)

FANG Liang, YANG Jun-Feng, HUANG Tao-Hua, ZHANG Hui, LIU Han-Xing, YUAN Run-Zhang

2004, 25(5):  806-809. 

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Two new niobates Ba₅YZnNb₉O₃₀ and Ba₅LaZnNb 9O₃₀ were synthesized by high temperature solid-state reaction in the BaO-Ln₂O₃-ZnO-Nb₂O₅ system. The crystal structure and dielectric properties were characterized by using X-ray powder diffraction, scanning electron microscope and dielectric measurements. The results show that Ba₅YZnNb₉O₃₀ belongs to ferroelectric phase of fully filled tetragonal tungsten bronze structure at room temperature with unit cell parameters: a=1.252 55(4) nm, c=0.395 30(2) nm. Ba₅YZnNb₉O₃₀ has significant relaxor behavior, and the phase transition from ferroelectric to paraelectric occurred at 25 ℃ as frequency was at 10 kHz. The room temperature dielectric constant(ε_r) of Ba₅YZnNb₉O₃₀ ceramic reached 456 at 1 MHz. While Ba₅LaZnNb₉O₃₀ belongs to paraelectric phase of fully filled tetragonal tungsten bronze structure at room temperature with unit cell parameters: a=1.257 31(3) nm, c=0.398 12(2) nm. The room temperature dielectric constant(ε_r) of Ba₅LaZnNb 9O₃₀ ceramic reached 316 combined with a low dielectric loss of 0.017 at 1 MHz.

A Study of Synthesis of LiCoO₂ Thin Films by Sol-gel Method

HUANG Zu-Fei, WEI Ying-Jin, LIU Wei, XU Xiao-Guang, WANG Chun-Zhong, MENG Xing, CHEN Gang

2004, 25(5):  810-813. 

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Layered LiCoO₂ thin films were synthesized on the substrates of monocrystalline silicon(111) wafers by sol-gel and spin-coating methods. LiNO₃ and Co(NO₃)₂ were used as raw materials. XRD results show that the total concentration of metal ions(Li⁺+Co²⁺) and the metal atomic ratio n(Li)/n(Co) in the coating solution can affect the composition in the films severely, and the best annealing temperature and time are between 600—700 ℃ and 30—60 min, respectively. Meanwhile, the contents of PEG, citric acid and deionized water in the coating solution and the speed of rising temperature have influence on the surface morphologies of the films strongly.

Synthesis and Crystal Structure of a Novel Pentanuclear Mo/Cu/S Cluster Compound [MoOS₃Cu₄(α-MePy)₆Br₂]

ZHANG Wen-Hua, LI Hong-Xi, CHEN Jin-Xiang, XU Qing-Feng, LANG Jian-Ping

2004, 25(5):  814-816. 

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Reaction of(NH₄)₂MoOS₃ with CuBr and AgBr(molar ratio=1∶4∶1) in α-MePy produced dark red crystals of [MoOS₃Cu₄(α-MePy)₆Br₂]. The product was characterized by elemental analysis, IR and X-ray diffraction. It crystallizes in a triclinic system with space group P1 and unit cell parameters a=0.950 9(3) nm, b=1.066 8(2) nm, c=2.153 6(3) nm, α=94.846(9)°, β=92.054(7)°, γ=99.299(8)°, V=2.145 5(8) nm³, Z=2, D c=1.828 g·cm^-3, F(000)=1 168, μ=42.79 cm^-1, R=0.049 and R_w=0.051. The compound consists of a nido-shaped MoS₃Cu₃ cluster unit and a four-membered CuBrCuS ring by sharing the same Cu3—S3 bond. The Mo atom and the four Cu atoms adopt a distorted tetrahedral geometry coordination. The Mo…Cu1, Mo…Cu2 and Mo…Cu3 distances are 0.271 1(3), 0 269 8(2), and 0.268 1(1) nm, respectively.

Synthesis and Crystal Structure of Zinc Coordination Polymer with Ferrocenedicarboxylic Acid as Ligand

LENG Si-Wei, WU Gang, XIN Ming-Hong, TANG Lu-Lu, ZHU Guang-Shan, FAN Yong, SHI Su-Hua

2004, 25(5):  817-819. 

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The title compound [Zn(Py)₂L]_n(L=1,2′-ferrocenedicarboxylate) was synthesized under mild conditions and its crystal structure was characterized. It crystallizes in a monoclinic system, space group C2/c with the cell parameters a=1.683 0(5) nm, b=1.380 4(3) nm, c=1.746 2(3) nm, β=108.78(2)°, V=3.840 8(15) nm³, Z=8, M_r=485.52, T=293(2) K, D_c=3.359 Mg/m³, μ= 4.073 mm^-1, F(000)=3 872, R₁=0.040 1, wR₂=0.113 2. The compound exhibits an unusual one-dimensional chain consisting of two zigzag chains.

Synthesis of a Series of Rhenium(Ⅰ) Bipyridyl Complexes as Photosensitive Dyes

SUN Shi-Guo, PENG Xiao-Jun, GAO Yun-Ling, L� Rong-Wen, SUN Li-Cheng

2004, 25(5):  820-822. 

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In order to study the effects of the substituted groups on the properties of the complexes, a series of rhenium(Ⅰ)₂,2′-bipyridyl complexes [fac-(4,4′-di-COOEt-bpy)Re(CO)₃(X—pyridine)PF₆], where bpy is 2,2′-bipyridine and X is 4-methyl, 3-hydroxy, 4-hydroxy, 4-amino, or H, were synthesized with a yield more than 90%, and characterized by ¹H NMR, ¹³C NMR, 2D-NMR( ¹H-¹H COSY, HMBC, HSQC), ESI-MS and HRMS. The δ H values on the X—pyridine ring were shifted to up-field in ¹H NMR and the MLCT absorbance maxima were red-shifted asthe X groups became more electron-donating from H to 4-methyl, 4-hydroxy or 4-amino. The ESI-MS and HRMS showed the mono-charged peaks and their isotopic peaks of the complexes. The absorption maximum of 1d(X= 4-amino) is 20 nm longer than that of 1e(X=H). It might be used to broaden the absorption range of solar cells.

Determination of Chemical Oxygen Demand with a New Photocatalytic Oxidation System

AI Shi-Yun, LI Jia-Qing, YANG Ya, CHAI Yi-Hao, SUN Zheng-Dong, JIN Li-Tong

2004, 25(5):  823-826. 

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A new photocatalytic method for the determination of chemical oxygen demand(COD) using nano ZnO-KMnO₄ co-existed system is described. The measuring principle is based on the fact that KMnO₄ acts as an acceptor of photogenerated electrons and then increases the rate of photocatalytic oxidation of organic compounds. The optimized operation conditions were selected and the photocatalytic oxidation mechanism was discussed. It is indicated that this method has mild operation conditions, it won′t cause secondary pollution, and can realize rapid and accurate determination of COD of surface water and drinking water. The application range is 1.5—10 mg/L and the lowest detection limit is 0.5 mg/L. The method was also applied to determining COD of real water samples. The results were in good agreement with those from the conventional methods(permanganate index method).

Simultaneous Separation of Five Anthraquinone Compounds inChinese Herb Rhubarb Extracts by Pressurized Gradient Capillary Electrochromatography

YAN Liu-Shui, WANG Zong-Hua, LUO Guo-An, WANG Yi-Ming

2004, 25(5):  827-830. 

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A pressurized capillary electochromatography with gradient elution for simultaneous separation of five active anthraquinone compounds in Chinese herb rhubarb extracts has been proposed. The experimental results show that under the optimal conditions the five anthraquinone compounds of Rhein, Aloe-emodin, Chrysophanol, Emodin and Physcion in Chinese herb Rhubarb extracts can be completely separated in 22 min. The column efficiency obtained by capillary electrochromatography with gradient elution is 4.6 times that by μ-HPLC with gradient elution, and the latter is 6.63 times that by μ-HPLC with isocratic elution. The developed method hasthe advantages of higher separation capacity, faster separation rate and less consumption of samples and solvents compared with previously reported HPLC and CE methods, and thus may be applied to the separation and determination of active components in complex matrix systems.

Analysis and Prediction of Protein Transmembrane Helical Regions

QIU Jian-Ding, LIANG Ru-Ping, TAN Xue-Cai, ZOU Xiao-Yong, MO Jin-Yuan

2004, 25(5):  831-836. 

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Membrane protein is a kind of especial protein in its structure, which is of vital importance for living cells and play a role in communication and in the transport of the cells with the outside world. Due to difficulties of experimental techniques, only a handful of membrane proteins have been characterized. Therefore, theoretical prediction methods are important for structure determination of this class of proteins. In this paper, a new method based on the combining of the continuous wavelet transform(CWT) with the hydrophobicity of amino acids is introduced to predict the number and locations of helices in membrane proteins. 1YST is chosen from the protein database as an example to describe the prediction of the number and locations of helices in membrane proteins by using this method. The performance and factors influencing the predicted results are studied in detail. To further investigate the feasibility of this method, we randomly choose 36 proteins from protein database asthe test objects, there are 232 transmembrane helices(HTM), 222 of them can be predicted accurately, the average predicted accuracy is 96.1%, which indicates that this method is an efficient tool to predict the HTM of proteins.

Studies on Icariin by Electrospray Ionization Mass Spectrometry

DOU Jian-Peng, LIU Zhi-Qiang, LIU Shu-Ying

2004, 25(5):  837-840. 

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Electrospray ionization mass spectrometry(ESI-MS) in both the positive and the negative ion modes has been used to analyze Icariin(Anhydroicaritin-3-O-α-L-rhamnoside-7-O-β-D-glucopyranoside). The results show that strong peak of [M+2H₂O-H]^- in the negative ion mode was readily observed. Through an experimental method of hydrogen and deuterium exchange, it is proved that the two H₂O is crystal water of Icariin. The collision-induced dissociation fragmentation pathways are different in the positive and the negative ion mode and they are proposed.

Electrochemical Property Study of Polyoxometalates Acid-polypyrrole Nanopaticles Glass Carbon Electrode Modified with a Macroporous Anodic Alumina Membrane

WANG Sheng-Tian, QIN Yu-Hua, ZHAI Sheng-Yong, ZHOU Li-Heng, XU Hong-Ding, LI Jing-Hong

2004, 25(5):  841-843. 

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A novel modified electrode was prepared by electrochemicaly cycling scanning the glass carbon electrode covered with a macroporous alumina membrane in a solution containing PPy and PMo 12O₃- 40. The reversibility of the cyclic voltammograms was improved obviously. The remarkable advantage of the modified electrode wasthe high sensitivity and favorable electrocatalytic behavior toward NO₂^-. The peak current increased linearly with the concentration of NO₂^- in the range of 8.0×10^-7—0.01 mol/L. The detection limit of NO₂^- was 1.0×10^-9mol/L. The polyoxometalates nanopaticles modified electrode exhibited almost the same electrochemical behavior after 7 d. It is indicated that the PMo₁₂-PPy/AGCE has a good reproducibility, stability and wide linearity range.

An Integrated Capillary Electrophoresis-Amperometric Detection Chip with Replaceable and Quasi-self-aligned Working Electrode

MENG Fei, CHEN Heng-Wu, DOU Yue-Hua, FANG Zhao-Lun

2004, 25(5):  844-846. 

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A glass capillary electrophoresis microchip with integrated amperometric detection cell equipped by replaceable micro-disk working electrode is described. The detection cell was fabricated as a buffer reservoir on the microchip. A micro-electrode-guiding hole, which was in alignment with the exit of the separation channel, was drilled into the bottom edge of the chip. When a micro-disk copper working electrode, the outside diameter of which being matched with the inside diameter of the guiding hole, was inserted into the hole, passed through detection cell and finally got access to the exit of the separation channel, the electrode could be quasi-self-aligned to the channel exit and fixed inside the guiding hole without the help of a micro-positioner. Thus an integrated end-column amperometric detection system with replaceable disk working electrode was established on the microchip. Good reproducibility of the electrode alignment was demonstrated by a 4 1% RSD in the detection of sucrose after repeated(n=9) alignment of a micro-copper disk electrode. The developed michrochip was used for separation and detection of oligosaccharides.

Enzyme Immobilization Technique in Microfluidic Channel on Integrated Chip

TIAN Yu-Ping, WU Hui-Ling, CHEN Shu-Gui, YANG Peng-Yuan

2004, 25(5):  847-849. 

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A new method for the immobilization of enzyme in microfluidic channel on the integrated chip for proteomic analysis was reported. The PDMS film immersing in the acrylic acid solution was irradiated under UV lamp to produce active free radicals and then immersed alternatively into the PDDA solution and trypsin solution for self-assemble. The monomer solution of the produced chip was characterized with the reflectance IR technique, contact angle determination and SEM observations. A standard protein BSA was selected to test the performance of the product. It was verified that CE and MALDI-TOF/TOF-MS detection can be on-line carried out in a single, successive running.

Microwave-assisted Dynamic Extraction of Flavonoids from Flos Sophaoae

LI Min-Jing, YOU Jing-Yan, LIU Zhong-Ying, ZHANG Han-Qi

2004, 25(5):  850-852. 

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Microwave-assisted dynamic extraction of the total flavonoids, rutin and quercetin from Flos Sophaoae was studied. The dynamic extraction with household microwave oven was applied, and at the same time was compared with Soxhlet extraction and the method of bath extraction with special microwave oven. The results indicated that comparing with Soxhlet extraction this method not only needed a shorter time, but also simplified the procedure, and made higher yield of the extraction, and comparing with bath extraction with special microwave oven, this method have the advantage of cheap, safe and being helpful to investigating the extraction process.

Purification and Structure Characterization of the Hyaluronic Acid Produced by a Streptococcus Zooepidemicus Mutation Strain

HONG Shui-Sheng, CHEN Jia, TENG Li-Rong, MENG Qing-Fan, ZHANG Jian-Guo, LIU Lan-Ying

2004, 25(5):  853-857. 

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A mutated strain of Streptococcus zooepidemicus capable of producing the polysaccharide in a high yield was obtained after being mutated bythe chemical agent N-methyl-N′-nitro-N- nitrosoguanidine(NTG). Polysaccharide produced bythe mutated strain of Streptococcus zooepidemicus was purified bythe procedure including Savage method, quaternary ammonium compound precipitation, DEAE-cellulose(DE52) column chromatograph and Sephadex G-75 gel filtration. The purified polysaccharide was proved to be hyaluronic acid(HA) by means of chemical composition analysis, ¹³C NMR, Infrared spectra, and circular dichroism. The single helix conformation of the purified HA was studied by Congo red experiment. The molecular weight of the HA was about 1.16×10⁶, which was measured by viscosity method.

Expression and Application of a Baterial Hemoglobin Gene in Penicillium Chrysogenum

ZHU Yan-Min, LIU Xiao-Jun, SUN Yan-Hong, ZHANG Jin

2004, 25(5):  858-861. 

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A exogenous gene expression system was established in P. chrysogenum strain by using acetamidase(amds) gene as selection markers. The Cytoplasm-PEG transformation system was constructed including preparations and reuses of P. chrysogenum Cytoplasm and expression of exogenous gene. The two plasmids pVHbM and pVHbⅠ for expression of VHb in filamentous fungi were constructed. We were able to introduce VHb gene into P. chrysogenum by co-transformation of plasmid pVHbM or/and pVHbI with the Selection pUcamds markers. Some of transformants integrated the VHb gene. The expression level of VHb protein was related with the position and copies for integrating VHb gene into chromosome of filamentous fungi, different transformants had different efficiency. Valence of penicillin enhanced by a factor of 39% in shake-flask experiments for penicillium chrysogenun YH876 variants.

Stereoselective Total Synthesis of (S)-(+)-α-Curcumene

LI An-Pai, LI Yang, DU Zhen-Ting, SHE Xue-Gong, PAN Xin-Fu

2004, 25(5):  862-865. 

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A facile stereoselective synthetic route to (S)-(+)-α-curcumene 1 was achieved by employing asymmetric dihydroxylation and reduction by Raney Ni in situ. After three steps, the key intermediates 7a and 7b were obtained. They were subjected the to reduction by AlHCl 2 to result in (S)-(+)-α-curcumene (1) in a high enantioselectivity and high yield. In the protective step of compounds 7a and 7b with MsCl in the presence of NEt 3, the elimination reaction and rearrangement were found and the corresponding diene 8 was afforded and elucidated by NMR method.

Chemoselective Reduction of 21-Azidocorticosteroids to Primary 21-Primary Aminocorticosteroids

PENG Jiu-He, LI Bing-Jie, HAN Chong, LI Zu-Cheng, CHENG Jin-Pei

2004, 25(5):  866-869. 

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The chemoselective reduction of 21-azidocorticosteroids to the corresponding 21-primary aminocorticosteroids was achieved with Zn/NH₄Cl as a reductant in reasonable yields(70%—85%). 11β-Hydroxyl-21-azidocorticosteroids were found to be easier to reduced to their amino counterparts more easily than 11-carbonyl and 11-deoxyl-21-azides. Aqueous THF was found to be the most suitable solvent for this reaction, and the ratio of water in the reducing system was crucial. In THF of 95%—97% in volume fraction and at 15 ℃, Zn/NH₄Cl can only reduce 11β-hydroxyl-21-azidocorticosteroids. To reduce the 11-carbonyl and 11-deoxy-21-azides, the volume fraction of water should be raised to 10% at least. This reduction method hasthe advantages of rather mild conditions, cheap and easily accessible reagents, and reasonable overall yields. Moreover, its simple work up and easy manipulation in large scale make our method superior to the reported Gabriel and 21-aldehyde oxime reduction procedures in the literature.

Studies on Synthesis of Multiaryl-substituted Imidazoles and Reversal Activity on the Multidrug Resistance

RUAN Ji-Wu, FU Li-Wu, HUANG Zhi-Shu, CHEN Li-Ming, MA Lin, GU Lian-Quan

2004, 25(5):  870-873. 

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Multidrug resistance(MDR) is one of the major obstacles to successful chemotherapy treatment of tumour. One of the main causes of MDR is linked to the overexpression of P-glycoprotein( P-gp). This study aimed to synthesize and characterize a novel class of triaryl-substituted imidazoles, a kind of potent inhibitors of P-gp mediated MDR. Their structures were characterized by elemental analysis, IR, ¹H NMR and MS spectra. Their reversal activities on the P-gp mediated MDR were tested by MTT method. The results reveal that compounds Ⅱ and Ⅲ have remarkable reversal activity in vitro, without apparently enhancing the toxicity of the co-administered drugs. Hence, they hold great promise as a kind of MDR modulators for the treatment of P-gp mediated MDR cancers.

Enantioselective Synthesis of MK-287

SHI Hong-Xin, LIN Hui, R. Bloch, G. Mandville

2004, 25(5):  874-876. 

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(2″S,5″S)-2-{3′-Methoxy-2′-propoxy-5′-[5″-(3′″,4′″,5′″-trimethoxyphenyl)tetrahydrofuran-2″-yl] phenylsulfonyl}ethanol(MK-287) which was potent PAF antagonist, was enantioselectively synthesized in eight steps by addition, oxidation, hot decomposition, hydrogenation and so on from (-)-4,10-dioxatricyclo-[5.2.1.0^2,6]-decene-3-ole(1). Asymmetry was introduced using the nucleophilic addition of the triisopropoxytitanium to the lactol 1. The second asymmetric center was installed by a highly stereocontrolled acid-assisted reduction with sodium cyanoborohydride of the hemiketal formed. The product MK-287 was optically pure.

Studies on the Mechanism of Deacylation and Condensation Reactions of α,α-Diacetyl Ketene Dibenzylthioacetal

AI Lin, XIAO You-Ping, LIU Qun, ZHANG Qian, WANG Mang

2004, 25(5):  877-879. 

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The behavior of α,α-diacetyl ketene dibenzylthioacetal 1a under basic conditions was studied. Catalyzed by steric hindered base ast-BuONa(int-BuOH), α-acetyl ketene dibenzylthioacetal 2a could be obtained in 98% yield within 3 min via deacylation of 1a. Assisted byt-BuONa(int-BuOH), α-cinnamoyl ketene dibenzylthioacetals were produced in high yields by reacting both 1a and 2a with arylaldehydes; whereas, under the same conditions, the corresponding α,α-dicinnamoyl ketene dibenzylthioacetals 4 were formed when furan-2-carbaldehyde and thiophene-2-carbaldehyde were used asthe electrophiles. These evidences support the proposed mechanism that, catalyzed byt-BuONa (int-BuOH), the reaction of 1a with arylaldehydes may normally proceed via a sequential deacylation-condensation process and the formation of double condensation products 4 may be due to the higher activity of furan-2-carbaldehyde and thiophene-2-carbaldehyde under the selected reaction conditions.

Theoretical Study of the Tautomerization Between Benzaldoximes and Their Polar Tautomers

XU Wei-Ren, WANG Jian-Wu, LIU Cheng-Bu

2004, 25(5):  880-883. 

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Three tautomerization reactions between benzaldoximes and their polar tautomers have been studied theoretically. All geometries of reactants, products and transition states were optimized by DFT method at B3LYP/6-31G(d) level with Gaussian 98 software package. The species with Z and E configurations have similar transition states in the three reactions. Compared with E isomers, Z isomers are favorable to the polar products. The mechanism of the first reaction involves proton migration from hydroxyl to nitrogen of oxime within single molecule through a triangle transition state . This reaction takes place difficultly at room temperature because of the high energy barrier. The second reaction is related to proton exchange within the dimers. The proton of hydroxyl group in one oxime moves to the nitrogen of another oxime of the dimer through a hexaangular ring transition state with a lower barrier. The reaction rate of this reaction is large,but the thermodynamic balances is not favorable to the products. The third path is a catalyzed reaction by methanol with a pentagonal transition states. The hydroxyl of methanol acts as a bridge of proton transfer. The reaction barrier and rate are moderate. Our results show that the tautomerization between benzadoxime and their polar tautomers can take place at room temperature. The main reaction path is the proton exchange within the dimers duo to its large reaction rate. The reaction will reach the end asthe product is consumed continuously.

Selective Hydrogenation of Halonitroaromatic Compounds Catalyzed by Water-soluble Bimetallic Catalyst Containing Ruthenium and Platinum

ZHOU Ya-Fen, CHEN Jun-Ru, LI Rui-Xiang, ZHAO Song-Lin, LI Xian-Jun

2004, 25(5):  884-887. 

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Selective hydrogenation of halonitroaromatic compounds catalyzed by water-soluble bimetallic catalyst containing ruthenium and platinum in the aqueous/organic two-phase system was studied. It was found that the reaction rate increased obviously due to the addition of Pt and Pd. Ru/Pt-TPPTS bimetallic catalyst exhibits a strong synergic effect when the molar ratio of Ru to Pt is 1/1. Under the conditions of 70 ℃, p H₂=1.0 MPa, the conversion of p-Cl-C₆H₄NO₂ is 100% in the presence of Ru/Pt-TPPTS catalyst, which is higher than that of Ru-TPPTS or Pt-TPPTS, the selectivity of p-Cl-C₆H₄NH₂ is more than 99%. The catalyst also exhibits a high activity and selectivity for the hydrogenation of other haloaromatic nitro-compounds with different substituents and substituted positions. Meanwhile, the amount of dehalogenation product(aniline) is about 1%.

Specific Saturation Capacity of Clusterization in Cluster of ROSO₃Na with Water-soluble Nonionic Macromolecules

FANG Yun, CAI Kun, ZONG Li-Yan, LIU Xue-Feng, HE Mo-Sha

2004, 25(5):  888-891. 

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The characteristics of bis-transition points in γ-lgc curves of surface active sodium alkylsulfates with water-soluble nonionic macromolecules such as PVP or PEG were studied, and saturation capacity of clusterization Γ_∞ and specific saturation capacity of clusterization [Γ_∞] of surfactant on macromolecule were calculated in accordance with the phenomena of pseudo double-plateau. [Γ_∞] of ROSO₃Na changes little with the chain length of both surfactant and macromolecule, as well as concentration of macromolecule. [Γ_∞]_reg are 8.96 and 3.74 mmol/L, or 0.394 m/n and 0.415 m/n for ROSO₃Na-PEG and ROSO₃Na-PVP respectively, which was obtained from regression of Γ_∞-c P. The results of t-test show that there is no significant difference between [Γ_∞]_reg and [Γ_∞]_exp, therefore, it is reasonable to express [Γ_∞], a supramolecular interaction parameter, as a constant for soft cluster of ROSO₃Na homologue with PEG or PVP respectively. It is deduced from the experimental results that the soft clusters are formed between normal pseudo-micelles of ROSO₃Na and macromolecules by supramolecular self-assembly force in which electrostatic interaction is dominant.

Interaction Mechanism Between Microperoxidase-8 and Eu³⁺

CHEN Ting-Ting, HUANG Xiao-Hua, DU Jiang-Yan, FENG Yu-Ying, LIU Chang-Peng, XING Wei, LU Tian-Hong

2004, 25(5):  892-895. 

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The interaction mechanism of microperoxidase-8 (MP-8) and Eu³⁺ was determined by using UV-Vis absorption spectroscopic and electrochemical techniques. The study of the UV-Vis absorption spectra indicated that when Eu³⁺ is added into the MP-8 solution, the Sored band shifts to the red direction and its absorbance decreases. The difference between the absorbance of the Soret band of the MP-8 solution without and with Eu³⁺ increases linearly with increasing the molar ratio of Eu³⁺ to MP-8 when the molar ratio is less than 3. When the molar ratio is larger than 3, the difference decreases with increasing the molar ratio. Their extension lines intersect at the molar ratio of 2. The electrochemical study showed that after MP-8 was added into the Eu³⁺ solution with the molar ratio of 10, the area of the anodic or cathodic peak of Eu³⁺ decreases about 20% comparing with that before adding MP-8. All the UV-Vis absorption spectroscopic and elelctrochemical results illustrated that Eu³⁺ ions would coordinate strongly with carboxy oxygen of two propionic acid groups of the heme group in an MP-8 molecule, leading to an increase in the non-planarity of the porphyrin ring, greater exposure degree of the heme group, and better reversibility of the electrochemical reaction of the MP-8 molecule. The excessive Eu³⁺ ions weakly interact with the oxygen-contained groups in the peptide chain, resulting in a slight alteration of the structure of the prophyrin group.

The Multicriteria-decision-making Simultaneous Optimization Based onGenetic Algorithm in Chiral Capillary Electrophoresis Separation

XIONG Jian-Hui, ZHANG Pu-Dun, SHI Xian-Zhe, ZHANG Yu-Kui, XU Guo-Wang

2004, 25(5):  896-899. 

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A methodology based on the combination of desirability function approach and genetic algorithm was applied to the multicriteria-decision-making simultaneous optimization of epinephrine enantiomers by capillary electrophoresis. Uniform design, an experimental design method, was employed to examine how the factors such as electrolyte concentration, pH, concentration of chiral selector and voltage affected resolution, analysis time and peak height. In order to achieve the simultaneous optimization of the three goals for efficient, fast and highly sensitive separation, the Derringer desirability functions were tested. The real-value encoded genetic algorithm was used to acheive the search for maximizing desirability and several optimal separation conditions were obtained. Under the optimized conditions, the values of total desirability functions were increased by 10.4% in comparison to those under the optimal condition defined by the uniform design experiment.

Studies on Diffusion Behavior of Simple Fluid in Micropores by Molecular Dynamics Simulation

LIU Ying-Chun, WANG Qi, LU Ling-Hong

2004, 25(5):  900-903. 

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The diffusion behavior of simple fluid argon confined in micropores was studied by molecular dynamics simulation. The effects of micropore type, pore width, temperature, and density on diffusivity were simulated and analyzed. The diffusivity in micropores is much lower than that of the bulk, and it decreases as the pore width decreases. The parallel diffusivity is obviously larger than the perpendicular one, and the diffusivity in the channel pores is lower than that in the slit pores. The temperature and density are also important factors that affect the diffusivity in micropores.

Synthesis,Structure and Electrochemical Performance of Vanadium Oxide Nanotubes

CHEN Wen, MAI Li-Qiang, XU Qing, PENG Jun-Feng, ZHU Quan-Yao

2004, 25(5):  904-907. 

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Vanadium oxide nanotubes (VO_x-NTs) were synthesized in a rheological phase reaction followed by self-assembling process and characterized by XRD, SEM, TEM, Raman, ESR, TG-DTA, XPS, and simulated battery. The results show that the black products consist majority of VO_x-NTs with length of 1—10 μm and diameter of 30—100 nm, whose walls consist of 3—10 VO_x layers with interlayer distance of 3.53 nm. Raman spectrum indicates the stretching or bending vibration of V—O, lattice vibration of layered structure and organic group vibration of template. ESR spectrum with no superfine structure confirms the presence of V⁴⁺ and the average valence of vanadium in the product is +4.30 on the basis of TG and XPS. The initial charge and discharge capacity of VO_x-NTs are 404 and 383 mA·h/g, respectively. The discharge capacity decreases to 180 mA·h/g after 50 cyclee, which can be attributed to the VO_x-NTs reacting with the electrolyte and isolating from the carbon particles during the charge-discharge.

Studies on Molecular Recognition of Imidazole Derivatives by Novel Chiral Tyrosine Tetraphenylporphinatozinc Complex

WANG Shu-Jun, RUAN Wen-Juan, ZHAO Xiao-Jing, NAN Jing, ZHU Zhi-Ang

2004, 25(5):  908-912. 

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Two kinds of novel chiral Zn porphyrin complexes were synthesized and characteried by means of elementary analysis, UV-Vis, ¹H NMR. Molecular recognition was studied between hosts and imidazole derivatives. Association constants of Zn(o-BocTyr)TAPP and Zn(p-BocTyr)TAPP with imidazoles increased in the sequence K(2-MeIm>K(Im)>K(N-MeIm)>K(2-Et-4-MeIm). Through circular dichroism spectra and theoretical calculation method, the chang of position in which imidazoles coordinated to host 1 was studied, it is important to study the structral characterization of porphyrin.

Theoretical Studies on Effect of Conformation on the Spin Multiplicity Ground State in Parity Ethylene Type Biradical System and Stability

WANG Li-Min, ZHANG Jing-Ping, XUAN Yu-Shi, WANG Rong-Shun

2004, 25(5):  913-916. 

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The effect of conformation on the spin multiplicity of ground state and it′s stability were investigated for parity ethylene type biradical system by means of comparative study with DFT, CASSCF and QCISD(T) methods. It is found that based on the continuous twisting of radical centers out of conjugation with the ethylene, both the absolute values and the tendency for the stability of triplet ground state (ΔE_S-T) of the investigated system change dramatically with variation the calculation methods. DFT and CASSCF methods cannot give a smooth change for ΔE_S-T, when the radical centers in the ethylene are twisted. However, the ΔE_S-T result obtained by QCISD(T) method offers a smooth change in the continuous twisting of radical centers. It is suggested that QCISD(T) method is reliable for dealing with the conformational problem of high-spin molecules. Furthermore, the ΔE_S-T values for ethylene type biradicals with one and two twisted radical centers were explored, respectively. When two or one radical centers in the ethylene are twisted sufficiently out of conjugation, and dihedral angles are close to 90°, ethylene turns into a weak antiferromagnet and weak ferromagnetic coupling units, respectively. Though the ethylene is a robust ferromagnetic coupling unit under planar conformation.

Studies on Promoting Catalysis of Sm³⁺ Towards Oxidation of Methanol on the Pt Electrode

DU Bing-Chen, LIU Jing-Hua, XUE Xin-Zhong, XU Wei-Lin, XING Wei, LU Tian-Hong, SANG Ge

2004, 25(5):  917-921. 

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Electrocatalytic performance of Sm³⁺ adsorbed on the smooth surface of Pt electrode toward the oxidation of methanol has been studied. The experimental results show that Sm³⁺ has a high promoting catalysis for electrocatalytic oxidation of methanol in electrolyte. According to the positive experimental data(cyclic voltammograms) and the theoretical analysis, one coordination complex Pt-Sm³⁺-CH₃OH may be formed and acted as a critical intermediate during the reaction of methanol oxidation. Some in-situ spectral characterizations are in the process to confirm the existence of the complex. The mechanism of promoting effect of Sm³⁺ toward the electrocatalytic oxidation of methanol was deduced.

Preparation of P(VDF-HFP)/PMMA Blend Polymer Electrolyte Membrane with Water as Material for Phase Separation and Pore Producer

ZHAO Yi, WANG Tao, XU Fan, JIANG Zhi-Yu

2004, 25(5):  922-925. 

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A new method is proposed to prepare blend polymer electrolyte by using water as the material for phase separation and pore producer instead of traditional organic material. The blend polymer electrolyte consisting of polyvinylidene fluoride-co-hexafluoropropylene P(VDF-HFP) and poly(methyl methacrylate) (PMMA) was prepared by this method. The SEM images show that the blend polymer electrolyte films have alveolate network structures, which benefit the increase of ionic conductivity. The interaction between two kinds of polymers within the blend polymer was confirmed by FTIR, XRD and DSC studies. The ionic conductivity for the blend polymer electrolyte film with m(VDF-HFP)∶ m(PMMA)=1∶1 was measured as 0.804×10^-3S/cm at 30 ℃ by using electrochemical impedance method. Compared with other approaches the method introduced here is a very easy, cost-saving, and more environmental friendly method.

New Photochemical Reaction of Uracil in Phosphate-buffered Saline Under UV Irradiation

LIN Feng, WANG Zhi-Min, WANG Yi-Fei

2004, 25(5):  926-929. 

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Under UV irradiation the photoreaction of pyrimidine bases in aqueous solution has involved three types of reactions, (1) namely nucleophilic addition of water, ethanol, or hydrogen cyanide at the 5,6-double bond; (2) dimerization by addition at the same double bond; (3) ring cleavage. It was reported that the presence of phosphates altered the course of the photolysis process of pyrimidine bases and derivatives under the irradiation of low pressure mercury lamp(LPML, 254 nm), but the role of phosphate in the mechanism was not clear. In previous papers we found a new type of the photoreaction(replacement reaction) of pyrimidine bases in phosphate aqueous solutions under the irradiation of medium pressure mercury lamp(MPML). The photoreaction of 1.0×10^-4 mol/L uracil in 0.05 mol/L phosphate solution by irradiation of MPML was reported and the photoreactive enhancement of uracil by adding phosphate was found, which produced a novel compound. The composition and structure of the compound was identified by elemental analysis, EI-MS, UV, IR, ¹H NMR, ¹³C NMR,³¹P NMR. Filter experiments demonstrate that the wavelengths(190—220 nm) in the spectrum of MPML are responsible for the phosphate-induced enhancement.

Synthesis of Methyl N-Phenyl Carbamate from Methanol and Phenyl Urea

WANG Jun-Wei, LI Qi-Feng, DONG Wen-Sheng, KANG Mao-Qing, WANG Xin-Kui, PENG Shao-Yi

2004, 25(5):  930-933. 

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In this paper, methyl N-phenyl carbamate(MPC) was firstly synthesized from methanol and phenyl urea. The effects of catalysts, including PbO, Pb₃O₄, Pb/SiO₂, ZnCl₂, FeCl₃, Mo/HZSM-5 and Pb/HZSM-5, material ratio and reaction condition on the synthesis of MPC were investigated, and the optimum reaction conditions were obtained. It was found that PbO showed a higher catalytic activity and MPC selectivity than those of other catalysts. The selectivity of MPC decreased while the conversion of phenyl urea increased with the increase of reaction temperature. Prolonging the reaction time enhanced the conversion of phenyl urea while suppressed the formation of MPC. Higher methanol/phenyl urea molar ratio favored the formation of MPC. The conversion of phenyl urea and the yield of methyl N-phenyl carbamate were reached 95.2% and 80.6%, respectively, under the optimum reaction conditions at 140 ℃ after 4 h reaction. The reaction mechanism was discussed based on the distribution of products.

Photoelectrochemical Study of Nanoporous TiO₂ Electrodes Sensitized by Porphyrin Derivatives with Different Substituents

PAN Kai, LIU Zhao-Yue, XU Jin-Jie, YU Miao, WANG De-Jun, BAI Yu-Bai, LI Tie-Jin

2004, 25(5):  934-937. 

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Nanoporous TiO₂ electrodes were sensitized by different porphyrin derivatives, terahydro- xyphenyl porphyrin(THPP) and teracarboxylphenyl porphyrin(TCPP). Both kinds of the sensitized electrodes were characterized by UV-Vis, FTIR and XPS. The results show that the interaction between TiO₂ and TCPP was stronger than that between TiO₂ and THPP. Under the same soaking conditions the amount of TCPP adsorbed by TiO₂ electrode was more than that of THPP adsorbed by TiO₂ electrode. Both kinds of the sensitized electrodes were assembled to photoelectrochemical cells. The photocurrent responses of the photoelectrochemical cell under different illumination directions were studied. Calculated from the current-voltage curve of photoelectrochemical cells, the overall light-to-electric energy conversion yield(η) of TCPP-sensitized cell was 0.13%, while the conversion efficiency of THPP-sensitized cell was 0.06%.

Nonequilibrium Thermodynamic Analysis for Extractive Distillation Process

LEI Zhi-Gang, LI Cheng-Yue, CHEN Biao-Hua

2004, 25(5):  938-941. 

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Nonequilibrium thermodynamic analysis for extractive distillation process was made. The separation criteria for implementing extractive distillation process were proposed, which will be theoretically helpful to the design of extractive distillation process. The mathematical equation of entropy generation, which can be used for energy-saving analysis, was deduced and verified to be reliable. The results presented in this work can only be applied to the tray distillation column and are in the linear range of nonequilibrium thermodynamics. Moreover, it is valuable for other special distillations with separating agent about why the process can be carried out.

A Primary Study on Photocatalytic Properties of ZSM-5 Zeolite

YAN Gui-Yang, WANG Xu-Xu, FU Xian-Zhi

2004, 25(5):  942-944. 

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The photocatalytic degradation of several organic compounds in airstreams was studied at room temperature by using a bed reactor packed with the commercial HZSM-5 and operated in a circulating mode. It was found that the raw HZSM-5 shows an unanticipated photocatalytic activity for oxidating ethylene, bromomethane and methyl orange. XRF and AAS analyses reveal that the photocatalytic activity of the ZSM-5 results from the trace amount of iron impurity in the sample, and the photoactivity is positively related with the content of iron. The primary results of characterization by XRD, DRS, XPS and SPVS suggest that the most of Fe existed in the framework of zeolite and in a tetrahedral coordination. The iron species might be excited by UV irradiation to form a charge transfer excited complex along with the ligands and an electron excited state of Fe 3+, which are responsible for the photocatalytic behavior of zeolites.

Preparation and Electrochemical Capacitance Characteristics of Co(OH)₂/HY Nano-composite

CAO Lin, LIANG Yan-Yu, KONG Ling-Bin, LI Hu-Lin

2004, 25(5):  945-947. 

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A novel strategy, which is better-suited for preparing materials with a very microscopic structure, is described and the whisker-like composite of Co(OH)₂/HY was prepared by using this strategy. In addition, the mechanism by which the growth proceeds is not very rigorously worked out. Due to the high dispersed capability of HY towards to Co(OH)₂ resulting in loose whisker-like microstructure of Co(OH)₂, small channels become available for the diffusion of OH - electrolyte ions through all Co(OH)₂ thin layer. Consequentially, the prepared composite shows a very high specific capacitance (483 F/g) and utilization (93%) of effective electroactive composition of composite.

Dynamic Mechanical Analysis for Network Structure of High Crosslinking Degree Unsaturated Polyester Modified by Polyethylene Glycol

ZHU Li-Xin, XU Jia-Rui

2004, 25(5):  948-951. 

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A series of reactive maleic anhydride terminated polyethylene glycol was synthesized and used as a toughening modifier of the unsaturated polyester specified for Bulk Moulding Compounds (BMC). It was shown that the toughening modifier could participate in the curing reaction of the unsaturated polyester and construct different lengths of soft segments in the network, which has significantly increased the impact strength of the unsaturated polyester, whereas other mechanical properties such as tensile strength, flexural strength and modulus remain unchanged. The dynamic mechanical behavior of the cross-linked unsaturated polyester network was investigated by DMA.

Interaction Between the Bimodal Micelles Self-assembled by PS-b-PAA and PS-b-PAPMA

ZHANG Wang-Qing, SHI Lin-Qi, AN Li-Ying, GAO Li-Chao, LIU Zhen, SHEN Xu-Dong, ZHANG Bang-Hua, HE Bing-Lin

2004, 25(5):  952-956. 

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The interaction between the binary micelles self-assembled by polystyrene-block-poly(acrylic acid) (PS-b-PAA) and polystyrene-block-poly(amino propylene-glycol methacrylate) (PS-b-PAPMA) in water was discussed in this paper. The results show the interaction between the binary micelles under a suitable condition results in the formation of a kind of special micelles called half-bred micelles through polymer chain exchanging between PS-b-PAA micelles and PS-b-PAPMA in water. A possible mechanism of chain exchanging is suggested for formation of the half-bred micelles.

Complexes of Interpenetrating Polymer Networks Exhibiting Synergistic Effect of Ionic and Electronic Conductivities

XIE Hong-Quan, HUANG Xu-Dong, GUO Jun-Shi

2004, 25(5):  957-960. 

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Interpenetrating polymer network was synthesized via reaction of castor oil, poly(ethylene glycol), toluene 2,4-diisocyanante and 2-vinyl pyridine in the presence of redox initiator and dibutyl tin dilaurate as the catalyst. Both yield and gel content of most IPNs are higher than 93%. The IPN was characterized by IR spectrum and gel content. The IPM obtained exhibits good mechanical properties, which are related with its crystallinity. When the IPN is complexed with LiClO₄, it exhibits an ion-conductivity, whereas when it is complexed with TCNE or TCNQ, it shows an electronic conductivity. When the IPN is complexed with both LiClO₄ and TCNE or TCNQ, it shows a mixed conductivity with a synergistic effect, i.e. the mixed conductivity is higher than either electronic conductivity or ionic conductivity. The mixed conductivity can reach 10^-3—10^-2S/cm at room temperature.

Influence of pH Value on the Conformation Transition of Silk Fibroin

XIE Xun, ZHOU Ping, DENG Feng, WU Pei-Yi, ZONG Xiao-Hong, YAO Wen-Hua

2004, 25(5):  961-965. 

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Both ¹³C CP-MAS solid state NMR and laser Raman scattering spectroscopy were used to investigate the influence of pH values on the conformation transition of silk fibroin of Bombyx mori silkworm. The regenerated silk fibroins in the phosphate buffer solution were used to imitate the silk fibroins of the gland. A series of membranes formed in buffer solutions with different pH values were obtained by the evaporation of water at room temperature(for mimicking the gradual loss of water in spinning process). The composes and conformation in the fibroin membranes were determined qualitatively by Raman and Generalized Two-Dimensional Correlation Raman Spectroscopy for amide Ⅰ region( 1 600—1 700 cm^-1) of the silk fibroins. There are four types of conformations at least existing in the fibroin membranes, including conformations of typical silk Ⅰ(α-form and/or random coil), typical silk Ⅱ(β-sheet), silk Ⅰ transition and silk Ⅱ transition, etc.. Based on the qualitative results from 2D Raman spectrum, the relationship between pH value and conformation contents in the studied systems was determined quantitatively by simulation of C_β peak (δ14.5—22) in ¹³C CP-MAS solid state NMR spectrum. The results show that acidic solution(pH=5.2) is more favorable than neutral(pH=6.9) and basic(pH=8.0) ones for the conformation transition from Silk Ⅰ to Silk Ⅱ because the silk fibroin molecular backbones are easier to extend and then to form β-sheets in acidic solution.

Studies on Grafting Modification of Collagen and Application to Preparation of Low IR Emissivity Coating

ZHOU Yu-Ming, SHAN Yun, CAO Yong, XU Qun-Hua, JU Huang-Xian, WU Zong-Han

2004, 25(5):  966-970. 

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More and more requirements are put forward to infrared stealth coating with the development of detection technology, therefore, the key point in the infrared stealth coating research is how to achieve the lowest infrared emissivity under the circumstance of being compatible of visible light and radar stealth. Indium oxide powder, which is commonly used for the sake of visible light stealth as a coloring pigment in the preparation of coating, has a high emissivity and cannot lower the emissivity of coating consequently. Collagen, a biomacromolecule material, is a triple helix composed of three polypeptide chains. Owing to a great number of dipoles and molecule-bound charges in collagen molecules, actually collagen is a bioelectret and has the properties of polarization, electrostatics and so on. Additionally, collagen molecule abounds in elements such as oxygen and nitrogen, which shows a good affinity to metal oxide, so collagen can be used to modify and stabilize metal oxide powder. But the native collagen adsorbs water easily so that it cant be directly put into application. In this paper, grafting copolymerization of collagen with methyl methacrylate(MMA) initiated by ammonium cerium nitrate(CAN) and 2,2-azo-bis-iso-butyronitrile(AIBN) was carried out in an aqueous medium. The coating was prepared by the composites of collagen-g-MMA copolymer and indium oxide nanoparticles. The effect of the grafting temperature and the extractive solvent on the copolymer and the IR emissivity of the coating of the composites thereof was studied, and at the same time, the mechanism for the decrease in the IR emissivity of the coating was discussed by contrasting the microstructures of the collagen/indium oxide and copolymer/indium oxide composites. The results showed that the collagen-g-MMA copolymer with a grain size of 40—80 nm could be prepared at 50—55 ℃ with acetone and distilled water as the extractive solvents. The coating prepared by t

Effect of the End-group Structure of Hyperbranched Polymers on Their Electrostatic Self-assembly Behavior

QIU Teng, TANG Li-Ming, TUO Xin-Lin, YOU Hu, WANG Xiao-Gong, LIU De-Shan

2004, 25(5):  971-974. 

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The electrostatic adsorption self-assembly behavior of three anionic hyperbranched polymers with the same backbone but different end-groups in the presence of poly(diallyldimethylammonium chloride)(PDAC) were investigated. The three hyperbranched polyanions all showed good self-assembly properties and the increase of bilayers were monitored by UV-Vis spectra. Similar to the linear weak polyanions, their self-assembly were much affected by the solution conditions, such as pH value and salt concentration. However, these behavior under different solution conditions was also controlled by the variation of their end-group structures. Furthermore, the surface morphology and the contact angle for water of the self-assembly film with hyperbranched polymers as the out-layer were also affected by the variation of end-group strutures of these polymers.

Molecular Dynamics Simulation of Single Polymer Chain Interpenetrating into a Two-chain Condensed Coils

ZHANG Zhu-Qing, YANG Xiao-Zhen

2004, 25(5):  975-978. 

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A merging process of one condensed polyethylene chain into a two-chain globule(each of which consists of 300 CH₂) was simulated by molecular dynamics. Examination of the energy variation during whole structural evolution and evaluation of the perturbation of new chain to the well-penetrated two chains were performed. It was found that after the two parts become one globule, each of the chains attempts either to be inside under anisotropy of surface tension, or to occupy all the space possibly in the system by conformational entropy. The interpenetration process was thus carried out under such competition. It was also found that the third chain perturbs the distance between mass centers of the two previous chains and causes the distance increasing, which was also supported by the radial distribution function analysis.

Fabrication of Microlens with Acrylated Hyperbranched Polyisophthalate

KOU Hui-Guang, ZHANG Wen-Quan, WANG Ke-Yi, SHI Wen-Fang

2004, 25(5):  979-981. 

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The fabrication of microlens based on a novel photopolymerizable formulation, consisting of acrylated hyperbranched polyisophthalate (HPIPA), 1,6-hexanediol diacrylate (HDDA) and Irgacure 184, with the free flow technique was presented. The good focalization and low chromatism of the fabricated microlens were obtained with scanning near-field optical microscope and measuring the optical transfer function versus spatial frequency, respectively. The positive effects of good compatibility with acrylated monomers and a low shrinkage degree for HPIPA on focalization have also been described. The further research work about the fabrication of microlens with acrylated hyperbranched polyisophthalate is in progress.

Application of Quantum Dots Labeling to the Interaction Between Reconstructed-phage Display Peptide and Insulin Receptor

LI Hong-Mei, LIU Han-Zhi, ZHANG Hao, ZHU Gui-Bin, WANG Li-Ping, YANG Bai, LI Wei

2004, 25(5):  982-984. 

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Luminescent quantum dots(QDs) are a promising alternative to organic dyes for fluorescence-based applications. Filamentous phage was labeled with QDs and its infective capability is observed after labeling. The experimental result shows that the labeling phage can still infect E.coli K91 normally. We have also developed the procedures for using QDs to label CHO-IR cells and Mouse Kidney tissue slice. The tissue slice remained stably labeled for over 10 d and the cells remained stably labeled even for over 5 months.

Dynamic Rheological Properties of Poly(methyl vinyl)siloxane Filled with Untrafine Porous Silica

HU Hong-Guo, ZHENG Qiang, TAO Xiao-Le

2004, 25(5):  985-987. 

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Dynamic rheological properties of poly(methyl vinyl)siloxane(PMVS) filled with ultratra silica (SiO₂) were analyzed on an advanced rheometric expansion system(ARES) at 25 ℃ by varying the strain (γ) and the frequency (ω). The results show that an incorporation of 5% SiO₂ into PMVS at 25 ℃ could be enough to impact a significant increase on the storage modulus (G′) of the uncured system, which is believed to be caused by the strong interactions among silica fillers. Meanwhile, γ dependence of G′ related to Payne effect was observed upon increasing γ amplitude, and no distinct “second plateau” was observed even the content of SiO₂ approached 20%. We owe this phenomenon partly to the surface esterification of silanols and partly to the unvulcanized PMVS.

Studies on Liquid Crystalline of Carbosilane Dendrimer of the Second Generation Containing Thirty-six 4-Nitroazobenzene Mesogenic Groups in Its Periphery

ZHANG Qi-Zhen, SHENG Xin, YIN Xiao-Ying, LI Guang, JI Yi-Ping

2004, 25(5):  988-990. 

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Liquid crystalline of a new carbosilane dendrimer of the second generation(D2) containing thirty-six 4-nitroazobenzene groups in its periphery was characterized by means of polarizing optical micrograph, DSC and WAXD. Mesogenic compound M5 exhibits threaded, schlieren and inversion lines texture of the nematic phase on the cooling from isotropic phase to solidified temperature. Dendrimer D2 shows the focal conic fan-shaped texture of the smectic A phase on the heating course from 69 to 187 ℃ and on the cooling course from 183 to 64 ℃. After cooling, the smectic E(S_E) phase with a texture of the focal conic fan-shape with stripes and concentric arcs appears from smectic A(S_A) phase. Phase behavior of dendrimer D2 in liquid crystalline state was K69S_A187I182S_A57S_E47K. The isotropic-smectic A transition enthalpy, smectic A-smectic E transition enthalpy and isotropic-smectic A transition entropy were 1.8, 4.5 and 4.0 J/(K·mol), respectively, and were in agreement with or close to those of small molecular liquid crystal.