Table of Content

24 March 2003, Volume 24 Issue 3

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Preface

Hydrothermal Synthesis and Characterization of an Open Framework Zincophosphate with Zn₄O₄ Tetrameric Clusters

XING Yan, FU Yun-Long, SHI Zhan, HUA Jia, ZHANG Ping, CUI Yan-Jie, PANG Wen-Qin

2003, 24(3):  377-380. 

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The organically templated single crystal of Zn₅(PO₄)₄·H₃N(CH₂)₄NH₃ was synthesized by hydrothermal method and its structure was determined by single-crystal X-ray diffraction. Crystal data: orthorhombic, space group Pnma with lattice parameters a=1.834 40(6) nm, b= 1.330 34(4)} nm, c={0^744 97(2)} nm, β=90°, V=1.818 01(9) nm³, Z=4, R₁=0.030 9, wR₂={0^080 4} . The framework is built up of a network of ZnO₄ and PO₄ tetrahedra. The Zn₄O₄ clusters in the compound are linked to PO₄ tetrahedra to form basket-shaped building units, which are connected to each other via oxygens, in an alternate up-down manner, to form the three-dimensional architecture.

Crystallization Kinetics of Zn(Val)SO₄·H₂O in Mixed Solvent of Water with Acetone

GAO Sheng-Li, FANG Yan, HU Rong-Zu, CHEN San-Ping, SHI Qi-Zhen

2003, 24(3):  381-385. 

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The optimum volume ratio of water to acetone for Zn(Val)SO₄·H₂O crystalling from the mixed solvent of water with acetone has been determined, which is 1∶10. The crystal growth process of the compound at 298.15 K is investigated by microcalorimetry. The experimental results show that it obeys the Burton-Cabrera-Frank dislocation theory. Moreover, the enthalpy of solution of Zn(Val)SO₄·H₂O in water has been measured at 298.15 K. The standard enthalpy of formation of Zn(Val) ²⁺(aq) has been calculated.

Cloning, Expression and Purification of a Functional Fusion Protein with Cytoplasmic Domain of Human Band 3

ZHENG Yu-Juan, XING Fei-Fei, SUN Li-Wei, LIU Li-Yan, ZHAO Da-Qing, NI Jia-Zuan

2003, 24(3):  386-389. 

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The cytoplasmic domain of human erythrocyte band 3(CDB3) gene was amplified by standard PCR method from plasmid pHB3 and constructed to be a recombinant plasmid pCDBHistag with an expression vector pET28b. Recombinant CDB3 fusion protein with Polyhistidine-tag was strongly expressed as soluble protein in E coli BL21(DE3) after induction with isopropyl-β-D-thiogalactopyranoside. Affinity chromatograpy chelating with Ni ²⁺ was employed to purify the recombinant fusion CDB3 protein. About 70% of aldolase activity could be inhibited by purified recombinant CDB3 similar as the result in human erythrocyte. It suggested that aldolase could bind with the purified CDB3 fusion protein in vitro. The high-level expression and easy purification of this recombinant protein should permit thorough studies of the interaction mechanism of CDB3 with its peripheral binding proteins.

Effects of CuCl₂ on Slow Vacuolar Ion Channels in Radish by Patch-clamp

ZHANG Li-Ping, YANG Pin

2003, 24(3):  390-393. 

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The action mechanism of Cu ²⁺ to Slow Vacuolar(SV) channels of Radish(Raphanus satirus L.) was investigated by using whole-vacuolar patch-clamp recording mode. It is shown that SV channel was a cation selective channel and it had voltage- and time-dependence. Cytoplasmic Ca ²⁺ could activate SV channel and the increase in cytoplasmic Ca ²⁺ led to enhancement of SV-type currents. The changes of SV current was shown after Cu ²⁺ with different concentrations was added to the bath. When CuCl₂ with different concentrations was added to the bath solution, SV currents have different effects. It was found that CuCl₂ with a lower concentration(<0.1 mmol/L) promoted the channel currents, while CuCl₂ with a higher concentration(>0.1 mmol/L) inhibited SV currents. When 1 μmol/L CuCl₂ was added to pipette solution, SV currents were inhibited remarkably. This result provides an important basis at the channel level for researching further the effects of Cu ²⁺ on physiological activities of plants and the effects of copper fertilizers on crops.

Hydrothermal Synthesis and Characteristic of [C₆N₂H₁₈]₂[Mo₅O₁₅(HPO₄)₂]·H₂O

LI Ya-Feng, CUI Wei, ZHU Guang-Shan, QIU Shi-Lun, FANG Qian-Rong, WANG Chun-Lei

2003, 24(3):  394-397. 

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C₆N₂H 18]₂[Mo₅O 15(HPO₄)₂]·H₂O has been obtained by using hydrothermal synthesis, and the results of X-ray single crystal diffraction show that the compound crystalliized in space group {P3(2)₂1} of trigonal system with a=1.123 1(1) nm, c=2.280 2(5) nm, V=2.491 1(7) nm³, D_x=2^835 {Mg/m³}, Z=6 and R=0.022 7, wR=0.067 5. The crystal structure of [C₆N₂H 18]₂[Mo₅O 15(HPO₄)₂]·H₂O is composed of two protoned tertramethyldiamine, [C₆N₂H 18] 4+₂, [Mo₅O 15(HPO₄)₂] 4- and one molecule water. In the anion H₂Mo₅P₂O 4- 23, five octahedral MoO₆ are connected by sharing-angle to form a pentagon and three oxygen atoms of two PO₄ tetrahedral is connected to five Mo atoms. Five octahedral MoO₆ and two PO₄ tetrahedral are connected to form this anion like flying saucer.

Preparation of PVC Membrane Electrode Modified by Novel Calix[4]arene Derivative and Electrochemical Recognition for Ag~+ in Acidic Solution

LU¨ Jian-Quan, HE Xi-Wen, ZENG Xian-Shun, WAN Qi-Jin,ZHANG Zheng-Zhi

2003, 24(3):  398-403. 

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Novel PVC membrane glassy carbon electrode modified by 25,27-dihydroxy-26,28-bis(3-benzothiazolylthiapropoxy)-5,11,17,23-tetra-tert-butyl calixarene(CAL-GCE) was firstly reported. The preparation method, voltammetric characteristic of the modified electrode and application in recognition for metal ions were investigated. The results show that the CAL-GCE has a selective voltammetic response to silver ion in 0.2 mol/L HNO₃ solution and can be applied in analysis. The calibration curve of Ag + ion covered a range of 5.0×10^-8-1.3×10^-6 mol/L, and the detection limit of the presented method for Ag + ion was 3.8×10^-8 mol/L. The method was simple, sensitive and reliable. The mechanism of the interaction of this system was also discussed.

A Thylakoid Membrane Biosensor Based on the Antagonism of Thylakoid-bound Enzymes for Determining Herbicide

LI Jian-Ping, PENG Tu-Zhi, HE Xiao-Rong, XIAO Hai-Jun

2003, 24(3):  404-409. 

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An electrochemical biosensor for determination of herbicide was prepared. It was based on the antagonism of herbicides on the decomposition of hydrogen peroxide catalyzed by the thykaloid-bound enzymes. The thylakoid membrane isolated from spinach leaves was immobilized by entrapment in polyvinylalcohol bearing styrylpyridinium groups(PVA-SbQ). The thylakoid membrane was fixed on the head of a platinum electrode. Oxidative current of hydrogen peroxide was detected by differential pulse voltammetry in Tris-HCl buffer solution(pH=7.4) containing 1×10^-3 mol/L NaCl, 5×10^-3 mol/L MgCl₂ and 0.01 mol/L hydrogen peroxides. Some herbicides have been detected in the concentration ranges of 3×10^-9-1.5×10^-7 mol/L for paraquat, 1×10^-8-3×10^-7 mol/L for diuron, 4×10^-8-3×10^-6 mol/L for prometryn, 1×10^-7- 5×10^-6 mol/L for atrazine and 1×10^-7- 5×10^-6 mol/L for ametryn, respectively. The method for immobilizing thylakoid in PVA-SbQ membrane was found to be promising to make enzymes stable for several months. The mechanism for this antagonism on the enzymatic decomposition of hydrogen peroxide has been discussed.

Square-wave Amperometric Detection for Capillary Electrophoresis

XIE Tian-Yao, LI Na, TANG Ya-Jun, RUAN Xiao-Lin, MO Jin-Yuan

2003, 24(3):  410-413. 

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A square-wave amperometric detection(SWAD) method for capillary electrophoresis(CE) using end-column detection was investigated. An alternating square-wave potential instead of a constant potential previously used was adapted on the working electrode and the alternating current was sampled as the analytical signal. The effect of square-wave amplitude, frequency, initial voltage and the influence of high separation voltage on the S/N ratio were discussed in detail. The advantages of SWAD over the other reported methods using constant potential amperometric detection were of higher stability and reproducibility of the metal working microelectrode and remarkable sensitivity in the reversible electrode process. A detection limit of 1×10^-7 mol/L(S/N=3) was obtained for dapamine.

Studies on Electrochemically Induced DNA Cleavage by Imidazole Copper Complex

ZHAO Guang-Chao, ZHU Jun-Jie, CHEN Hong-Yuan

2003, 24(3):  414-418. 

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There are a couple of quasi-reversible redox peaks of Cu(Ⅱ)-imidazole[Cu(Ⅱ)Im₄] with one electron process on Pt electrode. Fluorescence spectroelectrochemical experiments reveal that the Cu(Ⅰ) complex reduced by electrochemistry can be reoxidized by O₂ in air. In neutral Tris-HCl buffer, {Cu(Ⅱ)Im₄} can bind to DNA with the binding constant of 2.7×10 2 L/mol. Obviously, this is a weak interaction. However, it is an intercalative model which has been identified by the experiments of fluorescence and electrochemistry. A novel method for the cleavage of DNA by the electrochemically-induced process of the reduction of Cu(Ⅱ)Im₄ is established and differential scanning calorimetries(DSC) are used to detect the results of DNA cleavage.

Photo-induced Electron Transfer Between Adsorbed Heme Proteins and Nanosized Silver Particles

ZHENG Jun-Wei, ZHOU Qun, DING Hong

2003, 24(3):  419-421. 

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Photo-induced electron transfer between the adsorbed heme proteins and nanosized silver particles was studied by surface-enhanced Raman spectroscopy. The results show that the adsorbed microperoxidase and cytochrome c can be reduced under a continuous irradiation of 413 nm laser. The photo-induced reduction of heme proteins is ascribed to the excitation of free electrons in silver metal due to the surface plasmon absorption of the nanosized silver particles. The excited electrons are transferred into the affinity level of the adsorbed molecules, resulting in the reduction of the adsorbed molecules.

Nanometer Fluorescent Hybrid Silica Particle as Ultrasensitive and Photostable Biological Labels

QU Hui-Ying, YANG Huang-Hao, LIN Peng, LI Shun-Hua, YANG Wei, XU Jin-Gou

2003, 24(3):  422-424. 

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Recent advances in the nanomaterials, such as luminescent quantum dots, latex fluorescent nanospheres and dye-doped silica nanoparticles, have opened a promising field toward the development of luminescent biolabel. In this paper, we develop a kind of novel nanometer-sized fluorescent hybrid silica(NFHS) particles used as a sensitive and photostable fluorescent probe in biological staining and diagnostics. The NFHS particles are prepared by controlled hydrolysis of the fluorophore silica precursor using the reverse micelle technique. The fluorophores are dispersed homogeneously in the silica network of the NFHS particles and well protected from the environmental oxygen. In comparison with single organic fluorophores without incorporation, these nanoparticle probes are brighter, more stable against photobleaching and do not suffer from intermittent on/off light emission(blinking). The NFHS particles have also shown unique advantages over the existing common organic fluorophores, quantum dots, and latex-based fluorescent particles for biomolecule recognition in the following four major points: easy preparation, good photostability, high sensitivity, and low toxicity. The approach proposed in this article for making NFHS nanoparticles is a general one, and it is not restricted to a particular type of fluorophore molecule as selected in this study.

Spatial and Temporal Amperometric Monitoring Dopamine Release from Single PC12 Cells with Carbon Fiber Nanoelectrode

HUANG Wei-Hua, ZHANG Li-Yao, CHENG Wei, PANG Dai-Wen WANG Zong-Li, CHENG Jie-Ke

2003, 24(3):  425-427. 

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Carbon fiber nanoelectrodes(200-300 nm) were firstly used to amperometricaly monitor the dopamine release from single PC12 cells with temporal resolution and especially more higher spatial resolution than those obtained by using microelectrodes. When the nanoelectrode was in a distance 1 μm above the PC12 cell, only one peak signal corresponding to a single vesicle exocytotic event was detected caused from the stimulation with 1 mmol/L nicotine. The spatial difference of exocytosis was also detected by placing the electrode onto the different locations of the cell body, the results have demostrated that the spatial distribution of dopamine in cells is not uniform and the time for stimulating secretion is very different. Nanoelectrodes electrochemical method can provide a powerful tool for observing the temporal and spatial characteristics of the secretion from single cells directly.

Adsorptive Voltammetric Behavior of Resveratrol and Its Application at Silver Electrode

DONG She-Ying, ZHENG Jian-Bin, NING Yan-Li, GAO Hong

2003, 24(3):  428-430. 

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Adsorptive voltammetric behavior of resveratrol at a silver electrode was investigated. And based on this, a linear scan voltammetry for determination of resveratrol had been found. The adsorption corresponded to the Langmuir type isotherm curve, and the free energy of adsorption was caculated to be -46.21 kJ/mol at 298 K. The electrochemical parameters such as charge transfer coefficient α and standard electron transfer rate constant k_s were estimated. In 0.2 mol/L KNO₃+1.2×10 -4 mol/L KCl solution, resveratrol can give a sensitive anode peak at potential about 0.29 V(vs. SCE). The linear range between the peak current and the concentration of resveratrol is 2.0×10^-9 to 1.0×10^-8 mol/L and 1.0×10^-8 to 9.0×10^-8 mol/L, respectively. The detection limit is 4.0×10 -10 mol/L. The method had been applied to the determination of resveratrol in wine.

Cyclization Reactions of 3,3-Dimethyl-1-(1H-1,2,4-triazolo-1-yl)-2- butanone or Substituted 1-(1H-1,2,4-Triazolo-1-yl)acetophenone with Dibromide Compounds and Its Biological Activities

ZHANG Yao-Mou, CHEN Wen-Bin, JIN Gui-Yu

2003, 24(3):  431-435. 

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The title compounds 3 and 4 were prepared by nucleophilic substitution reaction of compounds 1 with dibromide 2. Their structures were determined by elementary analysis, 1H NMR, IR, EI-MS and X-ray diffraction method. The reaction procedure was also studied in detail. From the screening results of biological activities, most compounds possess good fungicidal activities, especially against Puccinia recondita.

Chemical Constituents from the Roots of Biondia Hemsleyana

TAN Xing-Gen, ZHANG Xiao-Rong, PENG Shu-Lin, LIAO Xun, DING Li-Sheng

2003, 24(3):  436-441. 

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Nineteen compounds were isolated from the ethanol extract of the roots of Biondia hemsleyana(Warb.) Tsiang through the repeated column chromatography on normal and reversed phase silica gel. By the spectroscopic and chemical evidence, their structures were elucidated as α-amyrin-3β-acetate(1), lupeol 3-hydroxyoctadencanoate(2), lupeol 3,5-dihydroxyeicosanoate(3), cycloeucalenol(4), 4-methoxy salicylic aldehyde(5), 4-methoxy salicylic acid(6), isovanillin(7), scopoletin(8), isovanillic acid(9), cleomiscosin A(10), 2-hydroxymethyl-5-methoxylphenyl-O-β-D-glucopyranoside(11), pregn-4-ene-3,20-dione(12), neridienone(13), daucosterol(14), pregn-5-ene-3β,17α,20α-triol-20-O-β-D-canaropyranoside(15), periplogenin-3-O-β-D-gluco pyranosyl-(1→4)-β-D-cymaropyranoside(16), pregn-5-ene-3β,20(S)-diol-3-O-[2-O-acetyl-β-D-digitalopyranosyl(1→4)-β-D-cymaropyranosyl]-20-O-β-D-glucopyranosyl-(1→6)-β-D-glucopyranosyl-(1→4)-β-D-digitalo pyranoside(17), pregn-5-ene-3β,20(S)-diol-20-O-β-D-glucopyranosyl-(1→6)-β-D-glucopyranoside(18, biondianoside C) and pregn-5-ene-3β,20(S)-diol-3-O-[β-D-glucopyranosyl]-20-O-β-D-glucopyranosyl-(1→6)-β-D-glucopyranoside(19, biondianoside D) respectively. All compounds were isolated from this genus for the first time and 3, 11, 18 and 19 were new compounds among them.

Studies on Molecular Recognition of Amino Acid Derivatives by Macrocyclic Chiral Phosphoramidates

DU Da-Ming, HUA Wen-Ting

2003, 24(3):  442-448. 

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In this paper, a series of new chiral macrocyclic phosphoramidates containing 2,5-diaryl- 1,3,4-oxadizole and (S)-methylbenzylamine and L-amino acid methyl ester units were synthesized and the structures were determined by 1H NMR, MS, IR spectra and elemental analyses. FABMS, NMR and IR techniques were used to study the molecular recognition phenomena. The phosphoramidate molecules can form hydrogen bond or aromatic π-π interaction with D-phenylglycine, L-phenylglycine or L-phenylalanine methyl ester hydrochloride and dipeptide according to the appearance of 1+1 host guest molecular peak in FABMS spectra, NMR chemical shift and coupling constant changes. The chiral molecular recognition ability of chiral macrocyclic phosphoramidate for D-phenylglycine methyl ester hydrochloride is stronger than L-phenylglycine methyl ester hydrochloride. The side chain also affect the recognition ability, smaller substituent is better than larger substituent for the recongnition. As for the guest molecules, the {D-phenylglycine} and L-phenylglycine methyl ester hydrochloride are better than D- or L-phenylalanine methyl ester hydrochloride for the recongnition, no inclusion for the D- or L-alanine and L-histine methyl ester hydrochloride.

Studies on Synthesis and Biological Activities of Analogues of Melittin

LI Shun-Zi, YAN Hu-Sheng, LIU Guo-Dong, HE Bing-Lin, JIANG Lu

2003, 24(3):  449-453. 

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Melittin(GIGAVLKVLTTGLPALISWIKRKRQQ-NH₂), a 26-residue peptide, is the major component of the venom of the honey bee Apis mellifera, exhibits highly potent antibacterial activity in addition to its hemolytic activity. A peptide corresponding to Melittin′s C-terminal 15 residues and 4 analogues with 15 residues, respectively, were designed and synthesized. The pure peptides were obtained by semi-preparative RP-HPLC. Analytical RP-HPLC showed a single peak and amino acid analysis showed that the peptides had expected amino acid compositions. Antibiotic activities, hemolytic activities, hydrophobicities and secondary structures of the peptides were studied. All these analogues exhibited potent antibacterial activities and had much decreased abilities to lyse human red blood cells. The antibiotic activities were roughly correlated with the hydrophobicities. The hydrophobicities of the residues farther from the basic cluster(KRKR), however, contributed more to the antibiotic activities. While the mechanism of hemolysis of peptides is not the same as antibacterial action. No clear correlation between the hydrophobicities or the hemolytic activities and the secondary structures(α-helical structures) was found.

Studies on Adsorption of Bilirubin by Crosslinking Poly(2-hydroxyethyl methacrylate) Adsorbents Containing Amino Group

LU Ling, YUAN Zhi, SHI Ke-Yu, HE Bing-Lin, LIU Bin, SHEN Bin, WANG Qi-Shun

2003, 24(3):  454-458. 

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Adsorbents for bilirubin were prepared by immobilizing amino group on crosslinking poly(2-hydroxyethyl methacrylate)(PHEMA) resins. The effects of adsorption temperature, ion strength, bilirubin concentration and human serum albumin on the adsorption properties for bilirubin were studied. It was shown that, this kind of adsorbent had a good adsorption efficiency and high adsorption capacity, and the adsorption performances of resins immobilizing hexanediamine and protonized hexanediamine were better than others. When adsorption temperature rose from 20 ℃ to 45 ℃, the adsorption percentage of resins immobilizing hexanediamine and protonized hexanediamine for bilirubin increased slightly, while that of resins immobilizing triethylenetetraamine increased below 37 ℃ and decreased above 37 ℃, which could be due to the stronger interaction between hexanediamine and bilirubin than that between triethylenetetraamine and bilirubin. The adsorption percentage decreased when ion strength increased. With the increase of the concentration of bilirubin in solution, the adsorption percentage decreased while the adsorption capacity increased. When the concentration of bilirubin was 750 mg/L, the adsorption percentage of resins bearing hexanediamine was near 80% and that of resins bearing protonized hexanediamine was over 90%, and the adsorption capacity were 29.84 mg/g and 34.60 mg/g respectively. Resins immobilizing hexanediamine and protonized hexanediamine could also adsorb bilirubin in the presence of albumin. The adsorption of bilirubin by the PHEMA adsorbents containing amino groups could be attributed to the interaction between amino groups on adsorbents and carboxyl groups in bilirubin and also the hydrophobic interaction and hydrogen bonds.

Determination of the Gas-Phase Proton Affinity of N-Dipropyloxy-phosphoryl Alkyl-alanine by Electrospray Ionization Mass Spectrometry with the Kinetic Method

CHEN Jing, CHEN Yi, JIANG Yang, ZHAO Yu-Fen

2003, 24(3):  459-461. 

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In this work, the change of gas-phase proton affinity of alkyl-alanine through the phosphorylation reaction was studied by the electrospray ionization mass spectrometry with kinetic method. It was proved that the phosphorylation could increase the proton affinity of small peptide. A proposal that proton affinity increase might be responsible for the sensitivity improvement of small peptide in mass spectrometry has been provided.

Synthesis and Characterization of LiAl_0.3Co_0.7-xMg_xO₂ with High Electrical Conductivity

LI Chang, XU Xiao-Guang, MENG Xing, WANG Chun-Zhong, DU Fei, JING Yan, HUANG Gui-Chun, CHEN Gang

2003, 24(3):  462-464. 

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A series of LiAl_0.3Co_0.7-xMg_xO₂(x=0.01-0.13) powders were synthesized and characterized by XRD and TEM measurements. The results show that the crystal size is under 1 μm. When x≤0.11, the peaks in the XRD patterns are very sharp which indicate that the materials are well crystallized. After indexing the peaks, it was confirmed that the materials formed an α-NaFeO₂ structure which ensured the lithium ions pass fluently during the charge-discharge process.

Studies on Nanometer TiO₂ Film Photocatalyst Supported on Stainless Steel Wire Gauze

ZHU Yong-Fa, LI Wei, HE Yu, SHANG Jing

2003, 24(3):  465-468. 

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Nanometer TiO₂ film photocatalyst on stainless steel wire gauze was prepared by using sol-gel method. The structure of the TiO₂ film on stainless steel wire gauze was characterized by SEM, TEM, AES and Raman techniques. The effects of dipping time, the concentration of PEG and calcining temperature on the photocatalytic activity of TiO₂ film were studied. The best photocatalyst was obtained when sol contained 10%(molar fraction) PEG 400 and the film was calcined at 400 ℃.

Preparation and Structure Characterization of a Mesoporous Solid Superacid Catalyst SO₄^2-/Zr-HMS

LIAO Shi-Jun, JI Shan, JIAN Qi-Fei, WANG Le-Fu, Vladimir Linkov, Leslie Petrik

2003, 24(3):  469-472. 

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A mesoporous solid superacid catalyst, SO₄^2-/Zr-HMS, was prepared by sulfating the mesoporous Zr-HMS, which was synthesized from TEOS-zrconium-HDA-H₂O-ethanol system, with aqueous solution of 0.5 mol/L H₂SO₄ followed by calcining at 550 ℃ for 3 h in static air. The structure of catalyst was characterized by XRD, and the acidity of the catalyst was investigated by Hammit indicator method, TG and NH₃-TPD. It is shown that the catalyst SO₄^2-/Zr-HMS possesses the structure of HMS and with the acid strength by -13.75(H₀). The catalytic activity of SO₄^2-/Zr-HMS in the esterification of phthalic anhydride with butanol is higher than that of SO₄^2-/ZrO₂.

In situ XPS Studies on the Anti-oxidation Effects of Nano-sized Ni-Co-B Amorphous Alloy

DAI Wei-Lin, CAO Yong, FAN Kang-Nian, DENG Jing-Fa

2003, 24(3):  473-476. 

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In situ XPS was used to study the anti-oxidation behavior of Co and B in nano-sized Ni-Co-B amorphous alloy and the relationship between the surface contents and the treating oxidation conditions by O₂ as well as the changes of the surface elemental contents with the depth of the sample. It was found that the elemental B was preferably oxidized, then the elemental Co could be oxidized. After all elemental B and Co were used up, the surface elemental Ni began to be oxidized by O₂. In addition, the oxides from B and Co were inclined to enrich on the surface after the oxidation. It was the preferential oxidation of B and Co that protected the Ni active centers from oxidation during the catalytic hydrogenation.

TD-DFT Study on Electronic Spectrum Property for Bis(8-hydroxyquinoline) Beryllium and Its Derivatives

LIAO Yi, SU Zhong-Min, CHEN Ya-Guang, KAN Yu-He, DUAN Hong-Xia, QIU Yong-Qing, WANG Rong-Shun

2003, 24(3):  477-480. 

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The molecular structures of the ground state and the first singlet excited state for organometalic complexes bis(8-hydroxyquinoline) beryllium (BeQ₂) and its three derivatives were optimized with the DFT B3LYP method and ab initio "configuration interaction with single excitations"(CIS) method respectively. The frontier molecular orbital characteristics and energy levels of BeQ₂ have been analyzed systematically in order to study the electronic transition mechanism. Electronic spectrum property of complexes have been investigated with time-dependent density functional theory(TD-DFT), which indicates that the emissions of BeQ₂ and its derivatives originate from the electronic π→π * transitions within ligands. These theoretical results suggest that it might be possible to tune the emission wavelengths and improve charge transfer properties through the effect of ligand substituent on the distribution of frontier molecular orbital.

Theoretical Calculation and Experiments of Diameter of Calcium Alginate Gel Microspheres

CHEN Yi-Qing, SUN Duo-Xian, SU Jing, YANG Jun

2003, 24(3):  481-484. 

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Gel microspheres of calcium alginate and alginate-polycation microcapsules are widely used as the mobilization of biology, controlled release of drug and biologic adsorbents. In this paper, gel microspheres of calcium alginate are prepared through electrostatic droplet generator and formula of theoretical calculation of diameter of gel microspheres is accordingly given under different conditions. The results of theoretical calculation show that diameter of gel microspheres is determined by the voltage, distance between positive pole and negative pole, inner diameter of needle, flow rates of syringe pump and physicochemical properties of alginate. The diameter of gel microspheres will decrease with increasing voltage and decreasing the distance between electrode and it has the lowest value, which is defined as the critical diameter of gel microspheres and is in a direct proportion to the inner diameter of needle. The uniform gel microspheres with different diameters are prepared through changing physicochemical properties of alginate and parameters of electrostatic droplet generator. In order to obtain good spherical and homogeneous beads, the optimum mass concentration range of sodium alginate is from 0.15 to 0.20 g/L. The experimental results match the theoretical calculation well. The formula of theoretical calculation can be widely used to study the effect of physicochemical properties of alginate and parameters of electrostatic droplet generator on the diameter of gel microspheres of calcium alginate.

Computer Simulation on the Change of Polymer Structure During Yielding

XU Chen-Guang, LIANG Tai-Ning, SUN Juan, HAN Ming, YANG Xiao-Zhen

2003, 24(3):  485-487. 

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Whether there is a structural change during yielding was studied by molecular modeling. The results indicate that bond length and bond angle change little while intermolecular interaction dominates the yielding process just as other studies showed. But a structural transition phenomenon called "atom jump" was found during the yielding. The displacements of some atoms exceed ten times of the average displacement of all atoms. In addition, the complexity of polymer chain packing induces the multiple atomic jumps around the yielding point, which can be used to explain properly why polymers have a broad yielding peak.

Theoretical Study on the Organic NLO Chromophores^-1,3-dithiol-2-ylidene Moiety as the Electron-donating Part

LIU Xiao-Juan, FENG Ji-Kang, REN Ai-Min, SUN Jia-Zhong

2003, 24(3):  488-491. 

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We designed 12 organic NLO chromophores with 1,3-dithiol-2-ylidene moiety as the electron-donating part. At first we optimize the geometry with AM1 method, then gain the spectroscopy using INDO/CI method which has been tested to be effective for the conjugated molecules. On the basis of this, we designed the program-SOS expression for calculating the first hyperpolarizability β and explained micro-mechanically in order to offer a theoretical instruction for exploring NLO materials possessing good properties.

Photo-induced Intramolecular Electron Transfer of Fluorescein-anthraquinone-methyl Ester and Detection of Its Charge-separated State

ZHANG Hai-Ping, ZHOU Ya-Lin, ZHANG Man-Hua, SHEN Tao, LI Yu-Liang, ZHU Dao-Ben

2003, 24(3):  492-495. 

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The diad composed of fluorescein and 2-methyl-anthraquinone(FL-AQ) has been synthesized and its photophysical properties have been examined by absorption, fluorescence spectroscopy and fluorescence lifetime. The charge-separated state formed by photo-induced intramolecular electron transfer has been detected by nanosecond transient absorption spectroscopy for the first time. When FL is excited in solution, the photo-induced electron transter from FL to AQ proceeds efficiently. The rate constant and the efficiency of intramolecular electron transfer are 3.95×10⁹s^-1 and 95% respectively. Its charge-separated state lifetime is too short to detect obviously by transient absorption spectroscopy. Adding of nanometer-size TiO₂ colloids to FL-AQ ethanol solution can prolong the lifetime of charge-separated state, so its transient absorption signal is recorded significantly. The decay lifetime of FL^+· at 480 nm is 11.1 μs. The decay lifetime of AQ^-· at 560 nm is 8.93 μs.

Studies on Deformation and Dissolution Behavior of Porous Nickel During the Oxidation/Lithiation in Molten Carbonates

CHEN Li-Jiang, LIN Chang-Jian, FENG Zu-de, CHENG Xuan

2003, 24(3):  496-500. 

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Based on the previous work, the deformation of porous nickel with time during the oxidation/lithiation in molten carbonates at 923 K under mix atmospheres was measured, under loading and without loading, respectively. The morphology of nickel samples after testing for different time was characterized by SEM. And the corresponding concentration of nickel ions dissolving in molten carbonates was detected by Atomic Adsorption Spectrometry(ABS). The results indicate that there was a severe dissolution of nickel during the oxidation/lithiation of porous nickel under loading condition, in addition, even if without loading, the dissolution of nickel from porous nickel was still obvious.

An EQCM Study of Adsorption and Oxidation of Glycine at a Pt Electrode in Acid and Alkaline Solutions

GU Yan-Juan, ZHOU Zhi-You, CHEN Sheng-Pei, ZHEN Chun-Hua, SUN Shi-Gang

2003, 24(3):  501-505. 

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Adsorption and oxidation of glycine at a Pt electrode were studied by using electrochemical quartz crystal microbalance(EQCM) in both acid and alkaline solutions. The results demonstrate that the behavior of adsorption and oxidation of glycine depends strongly on the acidity of solutions. The adsorption of glycine is weak in acid solution. However, glycine can be decomposed in alkaline solution to produce adsorbates that are stable on Pt surface below 0.0 V(vs. SCE). It has been revealed that the activity of glycine oxidation is higher in alkaline solutions than that in acid solutions. The surface mass change(Δm) and the average molar mass(M/n) of all adsorbates on Pt electrode surface per electron transferred in the above processes have been determined quantitatively through EQCM. An increase of 58.6 ng/cm² in Δm was detected in acid solutions for the process of hydrogen desorption from -0.25 to 0.11 V(vs. SCE) at Pt electrode, which was ascribed to the replacement of adsorbed hydrogen by the adsorption of water molecules or/and glycine anions. The EQCM frequency change in the oxygen region(between 0.35 and 1.20 V) was mainly caused by the adsorption of oxygen, the oxidation of adsorbed species and the oxidation of glycine, which resulted in an increase of 43.4 ng/cm² in the surface total mass change. This value is smaller than that(61.2 ng/cm²) acquired in a sulfuric acid solution free of glycine in the same potential region. In the case of alkaline solutions, the surface mass change of Pt electrode is related directly to the dissociative adsorption of glycine. When the upper limit of potential scan was set at 0.60 V, an increase in surface mass of 17.6 ng/cm² in the hydrogen region and an increase in surface mass of 43.0 ng/cm² in the oxygen region at Pt electrode have been determined.

Electrochemical Properties of La_0.8Sr (0.2)Ga_0.8Mg_0.2O_2.8 Electrolyte and Its Application to SOFCs

ZHA Shao-Wu, LI Hai-Bin, XIA Chang-Rong, LIU Xing-Qin, MENG Guang-Yao

2003, 24(3):  506-508. 

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Sr- and Mg-doped LaGaO₃(La_0.8Sr_0.2Ga_0.8Mg_0.2O_2.8) powders have been successfully synthesized from carbonate and oxides based on the principle of gelcasting. XRD patterns indicate the perovskite structure is formed without any second phases after sintering the powders at 1 400 ℃ for 6 h. The pellet sample was sintered to 98.3% of theoretical density at 1 450 ℃ for 18 h. The total electrical conductivity was greatly depended on the sintering time, and reached the maximum when the pellet was sintered at 1 450 ℃ for 24 h. Planar SOFC was constructed using Ni-Ce_0.8Gd_0.2O_1.9 and La_0.8Sr_0.2Ga_0.6Ni_0.4O_2.7 as the anode and cathode, respectively. When humidified hydrogen and air were introduced to the two electrodes, maximum power density of 252 mW/cm²(U=0.48 V, J=525 mA/cm²) was achieved with the open circuit voltage of 1.04 V at 750 ℃.

Studies on Electrooxidation of 3-Picoline to Nicotinic Acid

ZHANG Yu-Min, ZHANG Heng-Bin, CAO Xue-Jing, WANG Xin, JI Chang-Zheng

2003, 24(3):  509-512. 

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In an electrolytical cell with cation exchange membrane, the electrooxidatione reactions of 3-picoline on Pt or PbO₂/Ti electrodes were examined with steady state polarization curves. It was found that PbO₂/Ti electrode possesses electrocatalysis activity for synthesizing nicotinic acid. The effects of various factors on current efficiency were also examined by the product analysis with HPLC.

Branched Platinum Nanowires Prepared by Using Template Method

KONG Ling-Bin, LI Meng-Ke, LU Mei, GUO Xin-Yong, LI Hu-Lin

2003, 24(3):  513-515. 

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Porous anodic aluminum oxide(AAO) templates, obtained by anodization of aluminum sheets at relatively high voltages, were used for fabricating branched platinum nanowires which copy the three-dimensional branching structure of the nanochannels in the template. The formation of these branched nanochannels is the characteristic of AAO templates grown at 60 V in 0.15 mol/L H₂C₂O₄ solution. When AAO templates are grown at 40 V or lower, straight channels and platinum nanowires are obtained. Platinum nanowires array was alter-current(AC)-electrodeposited in AAO at a lower frequency(20 Hz) and increasing voltage(5-15 V). Compared with traditional AC electrodeposition condition, the deposition rate of platinum nanowires under this condition is slower and more controllable. Therefore, the platinum nanowires can perfectly copy the structure of the template. The as-obtained Al/AAO/Pt composite and branched platinum nanowires were characterized by X-ray diffraction(XRD) and transmission electron microscope(TEM), respectively.

Synthesis, Crystal Structure and Activity Study of 2D Polymeric Complex [MnNa(Salicylate)₂(CH₃OH)(H₂O)]_n·0.5nH₂O

SHI Wei, XU Ying-Kai, WANG Hong-Mei, LIU Yang 

2003, 24(3):  516-518. 

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In this paper, a novel polymeric complex [MnNa(Salicylate)₂(CH₃OH)(H₂O)]_n·0.5nH₂O was obtained and characterized by IR spectra, elemental analysis and single crystal X-ray diffraction. The titled complex is crystallized in triclinic system, space group P1 with a=0.763 82(15) nm, b= 1.037 1(2) nm, c=1.290 9(3) nm, α= 103.59(3)°, β=104.65(3)°, γ=109.50(3)°, V=0.873 6(3) nm³, Z=2, D_c=1.556 Mg/m³, M_r=409.20, μ=0.823 mm^-1, F(000)=418, R=0.0614, _wR= 0.147 6. The activity in catalyzing the superoxygen anionic free radical dismutation was determinated.

Preparation of Mono-component Silica Monolith via the Improved Bulk Sol-gel Process

LIU Wei, ZHANG Ya-Hong, GUO Na, ZHAO Yi-Yang, HAO Xiu-Feng, ZHANG Wan-Jin, WANG Ce {1}, WEI Yen

2003, 24(3):  519-521. 

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An improved bulk sol-gel process was found to prepare transparent, non-cracking, highly pure and mono-component monolithic silica gels with a low volume shrinkage. HSi(OC₂H₅)₃ was used as a gel acceleration to shorten the whole sol-gel processing time in the place of the carbonate powders in bulk sol-gel process. The mono-component silica gel monoliths prepared via the improved bulk sol-gel process possess a microporous structure and a good transmittance in the UV-Vis region, and the mass fraction of silica is 89%, the mass fraction of small molecules is 11%.

A Study on Catalytic Oxychlorination of Ethane to Vinyl Chloride

LU Xue-Ju, FEI Qiang, CHENG Tie-Xin, BI Ying-Li, ZHEN Kai-Ji, ZHANG Chun-Lei, CUI Yuan-Jun

2003, 24(3):  522-524. 

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Alumina supported CuCl₂ catalyst for oxychlorination of ethane was prepared by impregnation of γ-alumina with an aqueous solution of CuCl₂·2H₂O and KCl of a various mass fractions. Some samples containing 1%, 3%, 5%, 7%, 9% of Cu and 0%, 2%, 4%, 6%, 8% of K respectively have been investigated. The experiment results indicate that the catalyst containing 5%Cu and 6%K shows the highest yield and selectivity of vinyl chloride. With raising reaction temperature, the catalytic properties of the sample changes dramatically. The conversion of ethane was increased sharply from 320 to 395 ℃ and it was increased slightly from 3 95 to 440 ℃. At 440 ℃ the conversion of ethane and the yield of vinyl chloride are the highest. Then they are decreased slowly.

In situ MAS NMR Study on Propane Activation over Ga-modified H-ZSM-5 Under Mild Condition

ZOU Yan, SHI Lei, MA Zhuo-Na, ZHU Ka-Ke, HE He-Yong

2003, 24(3):  525-527. 

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C MAS NMR has been performed in situ to investigate the activation of ¹³C labeled propane under a mild condition over Ga-modified H-ZSM-5 catalysts prepared via different methods. The results indicate that the ion-exchanged and/or its related Ga species are the highly active catalytic components, while impregnated Ga species is not the active species for propane activation at 573 K.

Studies on Chitosan Rods Prepared by in situ Precipitation Method

HU Qiao-Ling, QIAN Xiu-Zhen, LI Bao-Qiang, SHEN Jia-Cong

2003, 24(3):  528-531. 

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A novel and simple method, in situ precipitation, was developed to prepare a high performance chitosan rod which is a potential material as the internal fixation of bone fracture, by using CS coagulation membrane as model to separate CS solution from 5% NaOH coagulation solution. CS rod(d=4.5 mm) with bending strength, bending modulus and shear strength of 92.4 MPa, 4.1 GPa and 36.5 MPa respectively was obtained when molecular weight(M_η) of CS was 56.3×10⁴ and the degree of deacetylate was 91%. SEM observed shows that CS rods prepared by in situ precipitation method has a concentric structure. The mechanism for preparing the gel rod was also discussed in this paper.

Studies on Viscosity Effects on Phase Separation Dynamics of Polymer Mixtures

JIANG Xiu-Li, ZHANG Hong-Dong, ZHANG Zhen-Li, YANG Yu-Liang

2003, 24(3):  532-536. 

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The simulation on the phase separations of binary fluids with the same and different viscosities has been done and the viscosity effects on the dynamics of phase separations are considered. We found that the domain growth exponent is controlled by the more viscouse phase in the on-critical cases. It reveals that the domain growth at the late stage is dominated by the component with a larger viscosity, which could be used to properly explain some experimental phenomena resulted from the viscosity effects. In off-critical cases, the growth exponent is the characteristic exponent of 1/3. It can be explained by the mechanism of droplet coalescene at the late stage of phase separation in an off-critical binary mixture. It is also demonstrated that in the absence of shear flow, the viscosity difference is not the reason for the inversed phase structure since no inversed phase structure has emerged during the phase separations in our simulation, even if the differences between the two components′ viscosities are very large.

Studies on Bulk Intercalation Polymerization of PMMA/Montmorillonite Intercalated Nanocomposite by Dynamic Torsion Vibration Method

ZOU Gang, FANG Kun, SHENG Xia, HE Ping-Sheng

2003, 24(3):  537-540. 

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The intercalation and dynamic mechanics behavior of PMMA in organ clay have been investigated by the dynamic torsional vibration methods. With the mechanical methods the cure process can be studied successfully. The Flory′s gelation theory and non-equilibrium thermodynamic fluctuation theory were used to predict the gel time t_g and the cure behavior of PMMA/organo-montmorillonite intercalated nanocomposites at various temperatures and Org-MMT loadings. The theoretical prediction is in good agreement with the experimental results obtained by so-called dynamic torsional vibration method, and the results show that the addition of Org-MMT increases the gel time t_g and reduces the rate of curing reaction. The last stage of polymerization of the PMMA in Org-MMT is similar to the cure process of the thermosetting resin and that implies the crosslinkings form. We can estimate the apparent curing activation energy and study the change of the mechanical behavior of the resin system corresponds to the change of the Org-MMT content. The addition of Org-MMT(MMT/MMA<5%) has no apparent effect on the apparent activation energy of the cure reaction.

Synthesis and Fluorescent Property of the Coordination Polymer of Eu(Ⅲ)-Dibenzoyl Methane-poly(acrylic acid/Styrene-acrylic acid)

TANG Jie-Yuan, ZHANG Wen-Gong

2003, 24(3):  541-546. 

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Luminescent rare earth complexes, particularly europium β-diketonates, have been intensively studied with respect to applications for luminescence. Recently, rare earth complexes have attracted considerable attention for organic electroluminescent(EL) devices as well as for optical microcavity emitters owing to their inherent extremely sharp emission bands and potentially high internal quantum efficiency. Their coordination polymers [Eu(Ⅲ)-DBM-PAA and NaEu(Ⅲ)-DBM-PSAA] were synthesized by the reaction of metal organic complex(NaEu(DBM)₄) with polyacrylic acid(M_n= 5 000) and copolymer of acrylic acid and styrene(M_n=3 000), the yields of Eu(Ⅲ)-DBM-PAA and NaEu(Ⅲ)-DBM-PSAA are about 89.7% and 87.3%, respectively. The coordination polymer was characterized by FTIR, UV, XPS and its composition and the structure were determinated. The result of electrical conductivity and elemental analysis indicate that each Eu(Ⅲ) ion is coordinated by carboxyl from two units in the Eu(Ⅲ)-DBM-PAA molecule or three units in the NaEu(Ⅲ)-DBM-PSAA molecule and one DBM^-. Their coordination polymer with Eu(Ⅲ) content reached up to 28.46% and 12.23%. The Eu-copolymer luminophores exhibited intense red light at 615 nm under UV excitation at room temperature, which is attributed to the ⁵D₀→ ⁷F₂ transition of Eu(Ⅲ) ions.

Preparation and Facilitated Oxygen Transport of Poly(vinylimidazole-co- fluoroalkyl methacrylate)-Cobaltporphyrin Complexed Membrane

SHENTU Bao-Qing, WENG Zhi-Xue, NISHIDE Hiroyuki

2003, 24(3):  547-550. 

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The membrane of poly(vinylimidazole-co-fluoroalkyl methacrylate)(FIm) complexed with meso-α,α,α,α-tetrakis(o-pivalamidophenyl)-porphyrinatocobalt(Ⅱ)(CoP) was prepared by complexing the imidazole residue of the copolymer on the fifth coordination site of CoP. Solvents had some effect on keeping CoP active during the preparation of the complexed membrane. The oxygen-binding properties and facilitated oxygen transport of the membrane were also studied. It was found that CoP fixed in the membrane had rapid and reversible oxygen-binding properties in response to the partial oxygen pressures. The oxygen-binding affinity of CoP fixed in the membrane was larger than that in the solution state. With the decrease of temperature, the oxygen-binding affinity of CoP increased. Oxygen permeation was selectively facilitated with CoP fixed in the membrane, and a high oxygen permeability [10^-10 cm³(STP)·cm·cm^-2·s^-1·Pa^-1] was observed in the FIm/CoP complexed membrane.

The Effect of Polymer Film Thickness on the Polymer Crystallization Restricted on Substrate

WANG Zhen, KONG Xiang-Ming, GAO Feng, HU Ping, XIE Xu-Ming

2003, 24(3):  551-554. 

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The study of thermal behavior of the crystalline polymer ultra-thin films was carried out in this paper. We focused on the effect of the thickness of the ultra-thin films on the melting temperature T_m and the crystallization temperature T_c. The ultra-thin films were made by means of spin-coater. The thicknesses of the films vary from about 20 nm to over 1 500 nm. The T_m and T_c of the ultra-thin films were measured by using differential scanning calorimetry(DSC). The results show that with the decrease of the film thickness, the T_m of PHB thin films first decrease gradually and then rise dramatically in a specific range, finally with further decreases of film thickness T_m decrease again sharply and the crystallization temperature T_c descended. The thermal behavior of the thickness of the ultra-thin films is discussed under a restrained condition.

Synthesis and Properties of Poly(ether imide)s Containing 3,5-Dimethyl Phthalazinone Moities

WANG Jin-Yan, XIAO Shu-De, JIAN Xi-Gao, ZHANG Shou-Hai

2003, 24(3):  555-558. 

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A series of novel poly(ether imide)s based on the dianhydride containing 3,5-dimethyl phthalazinone was synthesized and characterized. Poly(ether imide)s with intrinsic viscosities of 0.55-1.88 dL/g[in N-methyl-2-pyrrolidinone (NMP) at 30 ℃] were obtained by one-step solution polymerization in m-cresol. These poly(ether imide)s were readily soluble in some common organic solvents such as N,N-dimethylacetamide and NMP. The poly(ether imide)s derived from 4,4-oxydianiline and 4,4-methylenedianiline were also well soluble in 1,1,2,2-tetrachloroethane and chloroform. Glass transition temperatures determined by differential scanning calorimeter were in the range of 583-628 K. Degradation temperatures for 5% weight loss occurred all above 439 ℃ in nitrogen.

Circular Dichroism and Circularly Polarized Photoluminescence Spectra of a New Chiral Conjugated Polymers Based-on 1,1’-Binaphthyl Structure

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

2003, 24(3):  559-561. 

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A new chiral conjugated polymer was synthesized by the Wittig-Horner polymerization of optically active binaphthyl monomer at the 3,3-positions. The circular dichroism spectrum of the polymer shows that the degree of circular polarization in absorption, g_ abs, is 1.9×10^-3 in chloroform at room temperature. The circularly polarized photoluminescence spectrum of the polymer shows that the degree of circular polarization in emission, g_lum, is -1.6×10^-3 in chloroform at room temperature. As the polymer is readily soluble in chloroform, the results indicate that the circular polarization in absorption and emission is originated from molecularly dissolved chains and is due to exciton coupling between chain segments of the same polymer molecule. The results also show that the polymer could emit partially circularly polarized light when irradiated in chloroform at room temperature.

Oxygen-enriching Properties of a New Silicone Rubber Ionomer Membranes Containing Cobalt

ZHANG Zi-Yong, LIU Zong-Hua

2003, 24(3):  562-564. 

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A new type of silicone rubber membranes with facilitated transport properties for oxygen was prepared by using 11-alkenoic acid cobalt, a silicone rubber containing vinyl groups of 5%(molar fraction), a hydrogen-containing silicon oil and chlorine platinum acid. The solution casting and vulcanization were carried out simultaneously at room temperature. The studies on permselectivities show that O₂ permeability coefficients increase with decreasing oxygen pressure difference, but N₂ permeability coefficients are independent of nitrogen pressure difference. The cause is considered that a polymer cobalt complex is formed to possess an ability of facilitated transport for oxygen. This result leads to the increases in both oxygen permeability coefficient and oxygen/nitrogen separation coefficient at the same time. For example, oxygen permeability coefficient of 750 Barrer and oxygen nitrogen separation coefficient of 3.09 were obtained at a pressure difference of 0.05 MPa for the membrane containing 11-alkenoic acid cobalt of 2.5%(mass fraction). As high as 5% of 11-alkenoic acid cobalt could be added into the membrane, its oxygen permeability coefficient and oxygen/nitrogen separation coefficient increase to 802 Barrer and 3.34 at the pressure difference of 0.05 MPa, respectively.