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Table of Content

    24 July 2001, Volume 22 Issue 7
    Articles
    Studies on the Kinetics of Cobalt(Ⅲ) Complexes with Various Charge and Chirality Crossing Human Erythrocyte Membrane
    WU Gang, LI Rong-Chang, QIAO Xiu-Wen, WANG Jian-Cheng
    2001, 22(7):  1077-1080. 
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    The kinetics that four complexes with various charge and chirality crossed human erythrocyte membrane was studied, and their rate constants(k) of first-order kinetics were determined. The experimental results showed that the [Co(C2O4)3]3- has an obviously higher rate of cross-membrane[Co(en)3]3+than, [Co(en)2(C2O4)]+ and [Co(en)(C2O4)2]-,[Co(en)2(C2O4)]+and[Co(en)(C2O4)2]- the k values of the latter three kinds of complexes increased gradually with the decreasing of their positive charge, their mechanism of transmembrane transport are simple passive diffusion. The rate of transmembrane transport of [Co(C2O4)3]3- was obviously inhibited by DIDS, an anion channel inhibitor, the inhibition rate is 51.95%, its mechanism of transmembrane transport has been considered involving anion channel transport and passive diffusion. The uptake rate of L-[Co(C2O4)3]3- is larger than that of D-[Co(C2O4)3]3- by human erythrocytes, this exhibited that there was chiral selectivity when erythrocytes took up the optical isomers.
    Site Substitution and Energy Transfer of Eu2+ and Ce3+ in KMgF3:Eu and KMgF3:Eu-Ce Single Crystals
    SU Hai-Quan, JIA Zhi-Hong, SHI Chun-Shan
    2001, 22(7):  1081-1085. 
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    The high-resolution emission spectra of KMgF3:Eu and KMgF3:Eu-Ce single crystals were measured at 77 K. The site substitution of Eu 2+ and Eu 2+-Ce 3+ co-doped system in KMgF3 was discussed. Eu 2+ substituted for K+ sites on three differentsite symmetry: cubic, trigonal and tetragonal. The attribution of all lines occuring in the emission spectra were ascertained.The indirect energy transfer from 6P5/2 states of Eu 2+ to 4f 5d states of Ce 3+ in KMgF3:Eu-Ce was observed and the energy transfer mechanism was studied. The d-d interaction among levels was proposed.
    Effect of Chelate Reagents on Terbium-apotransferrin (Ⅱ)——The Properties of Anions Binding to Terbium-apotransferrin
    YANG Bin-Sheng, LI Ying-Qi
    2001, 22(7):  1086-1090. 
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    The removal of terbium from terbium apotransferrin by the chelate reagents, EDTA, HEDTA, CDTA, CIT, NTA, EDDA, IDAand SUC, were studied in 0.1mol/L N-(2-hydroxyethyl) piperazine-N'-2-ethanesulfonic acid and pH7.4 using UVdifferential spectra and fluorescence spectroscopies. Terbium fluorescence at 549 nm can be used to monitor the change from terbium-apotransferrin to terbium chelate. In the process of terbium removal there exists an intermediate, which is a ternary complex formed from terbium-apotransferrin (Tb-CapoTf) and the chelate reagent (L). When Lis a synergistic anion, the ternary complex is L-Tb-CapoTf while the ternary complex is Tb-CapoTf-Lwhen Lis a nonsynergistic anion. For the removal of terbium L-Tb-CapoTf is more effective than Tb-CapoTf-L. HEDTA, EDTA, NTAcan make Tb-CapoTf change into Tb-Lor Tb-L2 completely.
    Solvothermal Synthesis of Alkline Met al Selenides Cs2PdSe16 and Studies of Thermal Stabilities
    CHEN Zhen, WANG Ru-Ji, LI Jing
    2001, 22(7):  1091-1094. 
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    The solvothermal technique was used for the synthesis of Cs2PdSe16 and the crystal structure was determined by single crystal X-ray diffraction methods. Cs2PdSe16 crystallizes in the tetragonal, space group P4b2b2 with a =1.2601(2) nm, b =1.2601(2) nm, c =0.7044(1) nm, V =1.1185(3) nm3, Z=2, R=0.0514, wR =0.0991. The crystal structure consists of two dimensional layers of alternate layers of [CsPd(Se 4)2]- and [CsSe8]+. DSCresult indicates its decomposition temperature at 334 ℃.
    Preparation and Biodistribution of the 99mTcN-CPDTC Complex as a New Potential Brain Perfusion Imaging Agent
    ZHANG Jun-Bo, WANG Xue-Bin
    2001, 22(7):  1095-1097. 
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    The complex 99m TcN-CPDTC(CPDTC: N-cyclopropyl dithiocarbamate trihydrate) is synthesized through ligand exchange reaction. The two-step procedure involves the initial reaction of 99m TcO4- with succinic dihydrazide(SDH) as a donor of nitrido ligand(N3-) in the presence of stannous chloride dihydrate as reducing agent and propylenediamine tetraacetic acid(PDTA) as complex agent, followed by the addition of sodium N-cyclopropyl dithiocarbamate trihydrate. The radiochemical purity(RCP) of the product is over 90% as measured by thin layer chromatography(TLC). It is stable over 6 h at room temperature. Its partition coefficient indicates it is a good lipophilic complex. The biodistribution results in mice indicate that 99m TcN-CPDTCis significantly retained into the brain. The brain uptake(%, ID/g) is 4.64, 3.54 and 2.59 and the brain/blood ratio is 1.08, 1.27 and 1.28 at 5, 30 and 60 min post injection respectively. These results suggest potential usefulness of the complex as a brain perfusion imaging agent.
    Synthesis and GC Properties of Heptakis(2,6-di-O-pentyl-3-O-benzyl)-β-cyclodextrin
    SHI Xue-Yan, SHAO Qing-Long, TAO Dan-Ni, GU Jun-Ling, FU Ruo-Nong 
    2001, 22(7):  1098-1011. 
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    A β-cyclodextrin derivative, heptakis(2,6-di-O-pentyl-3-O-benzyl)-β-CD, was synthesized and used as GCstationary phase. The chromatographic results show that the CDs is a good GCstationary phase with a good film forming property, moderate polarity and good separation ability to disubstituted benzene isomers such as cresols and xylene isomers. The chromatographic properties of heptakis(2,6-di-O-pentyl-3-O-benzyl)-β-CDare better than OV-225 because of the peculiar cavity of β-cyclodextrin.
    Studies of Applications of a New Matrix——α-Cyano Ferulic Acid in MALDI-TOFMS
    DENG Hui-Min, ZHA Qing-Min, LI Jun, SHAO Wei-Yan, LAI Zhi-Hui, ZHAO Shan-Kai
    2001, 22(7):  1102-1104. 
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    This paper reports for the first time an experiment designed in which synthesized α-cyano ferulic acid used as a new matrix for the analysis of cytochrome c, trypsin, bovine serum albumin, β-cyclodextrin, dextrans and DNAd(T)18. The results demonstrated that α-cyano ferulic acid used as a new matrix could effectively desorb and ionize different kinds of samples, such as proteins and peptides, oligosaccharides, polysaccharides and oligonucleotides. In analysis of dextrans the new matrix gave better results when comparing with the normally used DHB. In analysis of DNAd(T)18, the sample could be desorbed and ionized more efficiently even withoutsample purification, which is normally needed when using 3-HPAas a matrix.
    A Solid-state Unsymmetrical Cyanine Dye Sensitized Nanoporous TiO2 Photoelectrochemical Cell
    ZHANG Li, REN Yan-Jie, ZHANG Zheng-Cheng, FANG Shi-Bi, TIAN He, CAI Sheng-Min
    2001, 22(7):  1105-1107. 
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    Anovel unsymmetrical cyanine dye(noted as CD) was applied to dye-sensitized nanoporous TiO2 photoelectrochemical cells. The incident photon-to-electron conversion efficiency up to 84.34% was achieved, which is notably high for cells employing pure organic dyes. To circumvent the sealing difficulties present in wet type cells, the solid-state cell was fabricated using poly(ethyleneoxide)(PEO) based gel network polymer electrolyte as charge transfer material between two electrodes. The resulting solid-state cell had an energy conversion efficiency of 0.86%, with open circuit voltage of 053 Vand short circuit current density of 0.96 mA/cm2 under 381 mW/cm2 white light illumination. The results show that the gel network polymer electrolyte is appropriate for assembling solid-state photoelectrochemical cells.
    Sol-gel-derived Macrocyclic Dioxopolyamine Stationary Phase for Open-tubular Electrochromatography
    ZENG Zhao-Rui, XIE Chuan-Hui, WANG Yuan-Chao, GUAN Na, FU En-Qin, CHENG Jie-Ke
    2001, 22(7):  1108-1110. 
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    This paper covers the preparation of a sol-gel-derived macrocyclic dioxopolyamine(1,4,7,10-tetraazaclotridecane-11,13-dione) stationary phase for open tubular capillary electrochromatography(OTCEC). The sol-gel-derived macrocyclic dioxopolyamine capillary columns have shown improved separations of neurotransmitters, isomeric nitrophenols, isomeric dihydroxybenzenes, isomeric aminophenols, isomeric diaminobenzenes and three ortho-halogen anilines, in comparison with those of untreated capillaries. The characteristics of the solgel-derived macrocyclic dioxopolyamine capillary columns are compared with the capillary column modified with the macrocyclic dioxopolyamine by chemically bonded method after etching. The sol-gel method provided a porous silica material with stationary phase in place within the same experimental procedure. This provided speedy fabrications of high-efficiency columns with high surface area and improved phase ratio. We achieved high efficiencies of 60000-340000 plates/m for the various isomeric compounds. The reproducibility migration time and the plate number were pretty good.
    Gaseous Dipeptide Complexes with Met al Ions by Electrospray Ionization and Tandem Mass Spectrometry
    CUI Meng, LIU Zhi-Qiang, SONG Feng-Rui, LIU Shu-Ying
    2001, 22(7):  1111-1113. 
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    Electrospray ionization(ESI) and tandem mass spectrometry have been used to investigate the gas phase interactions of five met al ions and seven dipeptides. For silver ion, two complexes([M+Ag]+ and [2M+Ag]+) were obtained as well as the one complex ([2M+M et2H]+) for transition met al ions. Upon collision activation, there is an obvious difference in MS/MSdata between met al ion complex and the protonated molecule. The fragment pathway of each complex is related to the structures of dipeptide and the nature of met al ion which suggest that there are several interaction between the met al ions and dipeptides in gas phase.
    Studies on High-resolution Hadamard Transform Microscopic Image Detection System Using One-dimensional Mechanical Mask
    CHEN Guan-Quan, TANG Hong-Wu, ZHOU Jin-Song, WU Qiong-Shui
    2001, 22(7):  1114-1116. 
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    Anovel Hadamard transform(HT) microscopic image detection system which can generate 511× 512 pixel format images of fluorescence or absorptive light for small samples has been developed, when spatial multiplexing is performed with a 511-slit one-dimensional Hadamard mask and a highly sensitive linear CCD. The weak native fluorescence imaging for Zephyranthes candida (Lindl.) Herb. Pollen cells can be realized within 1 min. The spatial resolution of 06 μm per pixel has been achieved with a 40× objective. The imaging speed, sensitivity and spatial resolution are satisfactory, hence the system has a good application prospect in cell biology and medicine. Some factors that influence imaging speed and quality have been discussed preliminarily.
    A CD and FT-Raman Study on the Secondary Structure of Saporin-S6
    WANG Yong-Ting, HUANG Pin-Wei, LI Zheng-Qiang, XU Fei, MENG Qing-Fan, YANG Yi, SHI Xue-Hui, LI Qing-Shan
    2001, 22(7):  1117-1119. 
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    Saporin-S6 is purified from the seeds of Saponaria officinalis and its CDand FT-Raman spectra are determined. From the CDspectra of fresh protein aqueous and the same aqueous that was laid aside for 90 days, it is proved thatsaporin S6 has unusual stability. Throughout the FT-Raman spectra of saporin-S6, we work out that the α-helix of saporin-S6 is 26%, while β-fold is 37%, and random coil is 37%.
    Studies on Tetra-substituted Amino Aluminum Phthalocyanine as a New Red-region Substrate for Mimetic Peroxidase
    CHEN Xiao-Lan, LI Dong-Hui, YANG Huang-Hao, ZHU Qing-Zhi, ZHENG Hong, XU Jin-Gou
    2001, 22(7):  1120-1121. 
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    Tetra-substituted amino aluminum phthalocyanine (TAAlPc) has been synthesized and used for the first time as a new red region fluorescentsubstrate for the determination of hydrogen peroxide catalyzed by peroxidase or mimetic peroxidase. Under optimum conditions, the calibration graph has a linear range of 0.0-3.0×10-7 mol/L H2O2 with a detection limit of 3.7×10-9 mol/L. The feasibility of TAAlPc as a new promising red region substrate in practical application has been proven in the determination of H2O2 in rainwater.The proposed method can largely minimize the interference that results from background fluorescence or scattering light and has a high analytical sensitivity.
    Investigation of Separation of Caffeine and Theophylline on Molecular Imprinted Polymer Stationary Phases by High Performance Liquid Chromatography
    SU Li-Qiang, LIU Xue-Liang, WANG Jun-De, SHANG Zhen-Hua
    2001, 22(7):  1122-1124. 
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    Molecularly imprinted polymer(MIP) stationary phases against caffeine and against theophylline were prepared. Separation abilities of the phases were investigated by HPLC. The results showed that the theophylline based MIPstationary phase is highly selective to theophylline, and base-lined separation of caffeine and theophylline was achieved. However, the caffeine based MIPstationary phase did not possess specific selectivity to the template molecule, caffeine. MIPwith specific selectivity to template molecule can only be prepared when interactions between template and monomer go together.
    Dual Fluorescence from Aqueous1-Naphthylamine Solutions of High pH——Excited-State Acidic Dissociation of Naphthylamine
    MA Li-Hua, WEN Zhen-Chang, SUN Xiang-Ying, JIANG Yun-Bao 
    2001, 22(7):  1125-1127. 
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    Dual fluorescence at ca. 447 nm and 545 nm was observed from the aqueous 1-naphthylamine (NA) solutions at pHhigher than 13.6. Similar dual fluorescence was also found with sodium 1-naphthylaminoacetate(NAA), but not with N, N-disubstituted 1-aminonaphthalenes such as sodium 1-naphthylaminodiacetate(NADA) and 1-dimethylaminonaphthalene(DMAN). No change in absorption spectra of NAand NAAwas observed in this pHregion.It was proposed that the dual fluorescence observed with NAand NAAwas due to the excited state dissociation of the primary and secondary amines at high pH. From the dual fluorescence intensity ratio pHtitration curve, the p Ka*' s of NAand NAAwere estimated to be between 14 and 15 which are much lower than the ground state p Ka. The novel approatch is such a simple, convenient and frequent analysis technique that it can be widely used in detecting the substitutional derivatives of aminonaphthalene.
    Studies on Electrostatic Adsorption of Proteins on Modified Surface
    PEI Ren-Jun, CUI Xiao-Qiang, YANG Xiu-Rong, WANG Er-Kang
    2001, 22(7):  1128-1130. 
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    The elucidation of key influence factors for electrostatic adsorption is very important to control protein nonspecific adsorption on modified surfaces. In this study, real-time surface plasmon resonance technique is used to characterize the electrostatic adsorption of two proteins (mouse IgGand protein A) on carboxymethyldextran-modified surface. The results show that protein solution pHand ionic strength are key influence factors for efficient electrostatic adsorption. The influence of protein solution pHon the amount of electrostatic adsorption depends on the type of the charge and the charge density of both protein and modified matrix on the surface. The electrostatic adsorption process involves a competition between the positively charged protein and other positively charged species in the buffer solution. Adecrease of ionic strength leads to an increasing electrostatic adsorption. The kinetic adsorption constants of protein Aat different pHvalues were also calculated and compared.
    Investigation of Thermal Unfolding Process of Cyanic Adduct of Horseradish Peroxidase by Fourier Transform Infrared and Circular Dichroism Spectrometry
    JIANG Jun-Guang, WANG Zhen-Xin, LIU Chang-Wei, LIU Dian-Jun, YANG Xiu-Rong, DONG Shao-Jun
    2001, 22(7):  1131-1133. 
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    Detailed circular dichroism(CD) and Fourier transform infrared(FTIR) studies have been carried out to monitor thermal unfolding of horseradish peroxidase isoenzyme C(HRP) inhibited by CN-(HRP-CN). The results suggest that HRP CNis quite different from native HRP with differentspin states of Fe of heme and different coordinated states. Cyanide becomes the sixth ligand of Fe(Ⅲ) of heme and the hydrogen binding network is destroyed partly at the same time, which cause the drastic decrease of thermal stability of HRP. The FTIRand Soret-CD spectra analysis demonstrate that during the heating process there is an intermediate state(I') which has both partly destroyed secondary and tertiary structures of native HRP, then it is the appearance of protein aggregation state(A) after fully unfolding. The unfolding pathway thus can be shown as follows: I——I'——U——A.
    Selection for Variables in Quantitative Structure-activity/Property Relationship Studies——Comparison Between Methods of Orthogonal Descriptors and Leaps-and-Bounds Regression Analysis
    ZHANG Wen-Jun, XU Lu
    2001, 22(7):  1134-1136. 
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    In this paper, the comparison of orthogonal descriptors and Leaps and Bounds regression analysis is performed. The results obtained by using orthogonal descriptors are better than that obtained by using Leaps and Bounds regression for the data set of nitrobenzenes used in this study. Leaps and Bounds regression can be used effectively for selection of variables in quantitative structure-activity/property relationship(QSAR/QSPR) studies. Consequently, orthogonalisation of descriptors is also a good method for variable selection for studies on QSAR/QSPR.
    EPR Study of Soluble Hydrogenase from Photosynthetic Bacteria Chromatium vinosum
    LONG Min-Nan, SU Wen-Jin, Albracht-S. P. J., ZHANG Feng-Zhang, XU Liang-Shu
    2001, 22(7):  1137-1140. 
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    Asoluble hydrogenase(SH) was purified from Chromatium vinosum by five step chromatography(DE-23, TSK-DEAE(I), Ultragel AcA-44, TSK-DEAE(Ⅱ), Superdex TM75) with a specific activity of 8.4 μmol H2/(min·mg prot). The oxidized SHyield two Ni(Ⅲ) EPR(electron paramagnetic resonance) signals( gx,y,z = 2.37, 2.16, 2.016 and gx,y,z = 2.30, 2.23, 2.016 ) at 45 Kwhich occurred in the other NiFe-hydrogenases. However, no[3Fe-4S] cluster EPRsignal was obtained at 10 K. When the SHwas reduced by H2 (over night at 8 ℃), the Ni(Ⅲ) EPRsignals disappeared, and an EPR signal from a reduced[4Fe-4S] cluster appeared( gx,y,z = 1.88, 1.90, 2.045). The results show that the soluble hydrogenase from C.vinosum is a new NiFe hydrogenase which catalyzes H2 production.
    Studies on the Asymmetry Total Synthesis of d-Biotin(Ⅱ)
    CHEN Fen-Er, LING Xiu-Hong, LÜ Yin-Xiang, ZHANG Xiao-Yue, PENG Xiao-Hua
    2001, 22(7):  1141-1146. 
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    An efficient and practical total synthesis of d-biotin is described.(4S,5R )-cis-1,3-dibenzyl-5-methoxycarbonyl-2-oxo-imidazoline-4-carboxylic acid, prepared from 1,3-dibenzylimidazolidone-2-cis-4,5-dicarboxylic acid via dehydration, monoesterification, optical resolution was subjected to reduction cyclization, sulfuration to produce (3aS,6aR )-1,3-dibenzyl tetrahydro 4-Hthienoimidazol-2, 4(1H NMR) dione(7). Compound 7 via Grignard reaction, dehydration, reduction, cleavage cyclization in one pot procedure led to (3aR, 8aS, 8bS )-1,3-dibenzyl-2-oxo-decahydromidazo thienothiolium bromide(11), which was converted to d-biotin via condensation, ring opening, hydrolysis, decarboxylation, debenzylation in an overall yield of 14.5%.
    Studies on Synthesis and Biological Activities of Novel Triazole Compounds Containing Sulfur
    CHEN Wen-Bin, JIN Gui-Yu 
    2001, 22(7):  1147-1151. 
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    The novel triazole compounds containing sulfur are synthesized by 1,4-nucleophilic addition-1,3-diaryl-2-[(1H NMR-1,2,4-triazol-1-yl)-methyl]-2 propen-1 one to substituted thiophenol. The structures of these compounds are determined by elemental analyses, 1H NMR and IRspectral data. These compounds are found to possess moderate degree fungicidal and better pesticidal activities by biological assay.
    Synthesis and Characterization of Main Chain Optically Active Copolymer of ω-Undecylenic Acid with Carbon Monooxide
    YUAN Jian-Chao, ZHANG Yu-Hua, CHEN Min-Dong, LÜ Shi-Jie, Wang-Dong-Mei
    2001, 22(7):  1152-1154. 
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    Enantioselective alternating copolymerization of carbon monoxide with ω undecylenic acid was carried out using cationic palladium catalyst modified by 1,4-3,6-dianhydro-2,5-dideoxy-2,5-bis(diphenylphosphino)-L-iditol (DDPPI). The chiral diphosphine was proved to be effective in the enantioselective copolymerization. The pure poly(1,4-ketone) was obtained by dissolving the copolymer containing spiroket al and 1,4-ketone units in1,1,1,3,3,3-hexafluoro-2-propanol and reprecipitating with methanol. Optical rotation, elemental analysis, spectra of 1H NMR, 13C NMRand IRshowed that our copolymer was an optically active, isotatic, alternating poly(1,4-ketone) structure. The copolymerization was carried out at 45 ℃ for 20 h. Molecular weight: Mn=1.1× 104 versus polystyrene,Mw/Mn=1.84. Molar optical rotation: [α]58920 =+43°(CH3COOC2H5, 5.0 mg/mL). The productivity of the copolymer of ω-undecylenic acid with carbon monoxide was 40.6 g copolymer/(g Pd·h).
    Epoxidation of Olefins by Ketone-H2O2 System
    ZHENG Yan-Song, XIAO Qin
    2001, 22(7):  1155-1156. 
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    Epoxidation of olefins was carried with an excellent yield by dioxiranes generated in situ by reaction of ketone with H2O2 in the presence of NaHCO3 in mixed solvent of acetonitrile and water. The catalytic activity of various ketones on epoxidation was studied for the first time. It is found that the ketone with electron-withdrawing group has an excellent catalytic activity and trifluromethyl ketone has the highest catalytic activity. Some bulky ketones with electron-withdrawing group show a very low catalytic activity. For olefins, the electron withdrawing group decreased the reactivity of the olefin and the electron donating group increased the reactivity, but the steric factor has little effect on the reactivity of olefins.
    Synthesis and Action of Opiate Receptor Binding of Endomorphin-1 and Their Analogs
    HUO Xiao-Feng, WU Ning, REN Wei-Hua, WANG Rui, Chen-Xin-Zi
    2001, 22(7):  1157-1159. 
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    Endomorphin-1(EM-1) and its six analogs which were designed by rationally replacing the 2-/3-amino acid(Aa) of EM-1 were synthesized by using liquid phase peptides synthesis method to study their action of opiate receptor binding(AORB). The order of their affinity intensity for μ opiate receptor(MOR) was  EM-1 >[ D-Ala2]EM-1 >[ D-Pro2]EM-1 > EM-1 >[ L-Tyr3]EM >[ L-Pro 3]EM >EM The sequence of their selectivity for MORis  EM-1 >[ D-Pro2]EM-1 =[ L-Tyr3]EM >[ D-Ala2]EM-1 =[ L-Pro3]EM >EM The results showed that, comparatively speaking, the 2-Aa was more closely related to the selectivity of EM-1 while the 3-Aa to their affinity, though the different replacement changed the AORBof EM-1 dissimilarly.
    Synthesis and Conformational Study of Schiff Bases Derived from o-Vanillin and Amino Acids
    SUN Ming, DUAN Yue-Qin, WANG Jin-Ling, LIU Xiao-Lan, MIAO Fang-Ming
    2001, 22(7):  1160-1162. 
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    Four Schiff bases derived from o-vanillin and amino acids have been synthesized and characterized by elemental analysis and IR. The conformations of four Schiff bases have been studied using molecular dynamics and quantum chemistry analysis approaches. The results revealed that the trans C=N with Rconfiguration of the title compounds are more stable than their Sconfiguration and there was a negative charge hole in the Schiff base, which shows the high possibility of forming stable complexe because met al ion is easy to enter this negative charge hole.
    Crosslinked Cornstarch Matrix for Slow Release of Carboxylic-containing Herbicides
    ZHU Zhi-Feng
    2001, 22(7):  1163-1165. 
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    Anew way for preparing crosslinked starch matrix for slow release of carboxylic-containing herbicides had been investigated and proposed. The matrix was crosslinked by formaldehyde in encapsulation process in order to reduce the swellability and release rates, and to raise the performance of slow release and resistance to water. By using 2,4,5-T and 2,4-D as model herbicides, the improvement on swellability, encapsulation efficiency and release characteristic of the crosslinked matrix as compared with native starch had been evaluated. The effects of formaldehyde amount, herbicide contents, and particle sizes on the matrix behavior and release rates were also investigated.
    Separation and Analyses of Uremic Middle Molecules by Chromatography and Matrix-assisted Laser Desorption/Ionization Time-of-flight Mass Spectrometry
    CHU Jie-Gen, YUAN Zhi, WU Qiang, HE Bing-Lin
    2001, 22(7):  1166-1168. 
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    Sera and urine from patients with severe uremia and healthy subjects were seperated by means of gel permeation chromatography on Sephadex G15 column with N(C2H5)3 H2CO3 buffer as eluent. Two middle molecular peaks(A and B) were detected at 206 nm in normal urine, uremic serum and uremic urine, but these two peaks were hardly observed in the profile of normal sera. In contrast, the absorption at 206 nm of fractions Aand Bfrom uremic serum and urine were less than that of fractions Aand Bfrom normal urine. Fractions Afrom normal urine, uremic serum and urine were collected and resolved into 8 to 9 subpeaks at 230 nm by anion exchange chromatography. One of these subpeaks, A-3, was detected in uremic serum and normal urine but undetectable in uremic urine. After a gel permeation chromatography with bidistilled water as eluent for desalting, subfraction A-3 was seperated into two parts designated A-3-Ⅰ and A-3-Ⅱ in order. The results of MALDI-TOF-MSrevealed that the two peaks from both samples were identical respectively, fraction A-3-Ⅰ contained three kinds of components with molecular weight 839.69, 1007.94 and 2015.16 and fraction A-3-Ⅱ consisted of other three kinds of components with molecular weight 873.69, 1106.67 and 1680.28.
    Studies on 12-Tungstophosphoric Heteropolyacid Supported SBA-15 Catalysts
    ZHANG Xue-Zheng, YUE Ying-Hong, GAO Zi
    2001, 22(7):  1169-1172. 
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    Aseries of SBA-15 supported H3PW12O40 (PW) catalysts were prepared and characterized. PWcrystal phase was not observed in XRDpatterns at PWloading as high as 60%. PWdispersed on the supports retains its Keggin structure, but a strong chemical interaction between PWand SBA-15 supports is present. The activity of the catalysts can be adjusted by varying PWloading. PW/SBA-15 catalysts are promising mesoporous solid acid catalysts for medium strong and weak acid catalyzed reactions.
    Studies on the Thixotropy of Ferric Aluminum Magnesium Hydroxide/Montmorillonite Suspension
    LI Shu-Ping, HOU Wan-Guo, SUN De-Jun, ZHANG Chun-Guang
    2001, 22(7):  1173-1176. 
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    The study on the thixotropy of aqueous dispersion consisting of ferric aluminum magnesium Hydroxide(Fe-Al-Mg-MMH) possessing permanent positive charges and Na montmorillonite(MT) possessing permanent nagative charges is reported. It was found that the suspension studied may display positive thixotropy, negative thixotropy or complex thixotropy depending on the Fe-Al-Mg-MMH/MTmass ratio(R). Two kinds of complex thixotropy were found, one is that the system may display a positive thixotropic character and negative thixotropic character successively, and the other is that the system may display a negative thixotropic character and positive thixotropic character successively. In the studied range of R (0-0.091), with increasing R, the thixotropy of the suspension changes from positive thixotropy through complex thixotropy and then to negative thixotropy. The effects of rest time( ts) after cessation of high intensity and the low shear rate( DL) used at measuring viscosity on the viscosity change for Fe-Al-Mg-MMH/MTsuspension were examined. It was found that the suspension which shows negative thixotropy at low D Lmay display complex thixotropy, first negative thixotropic character and then positive thixotropic character, at high DL. The system which is negative thixotropy at low ts may display complex thixotropy at high ts. The mechanism of the thixotropy is discussed, and the change process of "dispersed particles steric continuous network structures over the whole system-densed floc units" and "dispersed particles-densed floc units clusters of densed floc units" is proposed to explain the complex thixotropic phenomenon observed.
    Relationship Between Stability and Topological Properties of Two-dimensional Foam
    HAN Guo-Bin, WU Jin-Tian, XU Xiao-Ming
    2001, 22(7):  1177-1180. 
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    An experimental study of the evolution of two dimensional foam is presented. The topological properties of two-dimensional foam as a function of the evolution time were investigated, and the relationship between the topological properties and stability of two dimensional foam was discussed. In the evolution of two dimensional foam, two distincts tates were observed: a transients tate characterized by the presence of ordered state and a long-term fully disordered state. The long-term behavior of the foam shows that the average bubble area increases as a power law with exponent a =1.5, which is deviated from Von Neumann law and the possible reasons discussed. In addition, the distribution of sides of bubbles and the second moment of the distribution of number of sides are also discussed.
    Calculation of RRKM Microcanonical Dissociation Rate Constant of Small Linear Carbon Clusters Cn(n=7~10)(Ⅱ)
    WANG Hai-Yan, HUANG Rong-Bin, CHEN Hong, ZHANG Qiang, ZHENG Lan-Sun 
    2001, 22(7):  1181-1184. 
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    Ab initio calculation has been applied to calculating the dissociated pathways of small carbon clusters. Linear C7, C8, C9 and C10 and their transition states were optimized at MP2/6-31G* level, and their vibration frequencies were also calculated and analyzed. Based on the calculations, activation energies of the clusters were computed and their microcanoncial decomposition rates of different dissociation pathways were estimated by RRKMtheory. The calculation resultshows that the small carbon clusters tend to lose a C3 fragment during dissociation. It is also the main dissociation channel observed in the dissociation experiments of carbon cluster ions with a linear or ring configuration.
    Theoretical Study on Electric Structure and Ferroelectric Property of PbTiO3 Nanocrystals
    YU Hai-Tao, FU Hong-Gang, CHI Yu-Juan, MIN Xin-Min, ZHANG Xin
    2001, 22(7):  1185-1188. 
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    Quantum chemistry calculations of PbTiO3 nanocrystals were carried out by means of the cluster model via DFT-DVMcalculating program on which the regularity among the bond lengths, bond orders, and valance charges are drawn. The analyses of the population and the density of state (DOS) show that the interaction among3 d of Ti, 2 p of O, and 6 s and 6 p of Pb atomic orbitals causes the dipole moment and spontaneous polarization on the axis of the crystal, which results in the appearance of ferroelectric phase, the dipole moment and the intensity of the spontaneous polarization were calculated as well.
    Theoretical Studies on Vibrational Spectra of ClC(O)NCS
    XUE Ying, XIE Dai-Qian, YAN Guo-Sen
    2001, 22(7):  1189-1192. 
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    The optimized geometries, vibrational force fields and infrared intensities of trans and cis forms of ClC(O)NCSwere calculated by density functional theory (DFT) method with 6-31G* basis set. The theoretical force fields of B3LYP/6-31G* were scaled by using the scaled quantum mechanical (SQM) force field method. The scale factors were taken from the previous results of Pulay. The average deviations between the experimental and computed frequencies are 7.3 and 8.1 cm-1 for the trans-and cis-isomers of ClC(O)NCS, respectively. The assignments of the fundamentals for the two rotational conformers of this molecule were also performed according to the potential energy distribution (PED) and the infrared intensities.
    Lewis Acidity of Boron Trihalide: with Density Functional Theory Study
    YU Dian, CHEN Zhi-Da, WANG Fan, LI Shu-Zhou
    2001, 22(7):  1193-1196. 
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    Density functional theoretical calculations on BX3 (X=F, Cl, Br) have been carried out at LDA/NLlevels in order to interpret the experimental Lewis acidity scale for these molecules studied. An alternative calculation method for chemical hardness, based on the Janak's extension of density functional theory for fractional occupancies, is employed in the study of the Lewis acidity of boron trihalide. It is shown that the acidity of boron trihalide can be understood in term of the hardness. The molecular hardness calculated from the valence orbital hardness is found to be the best characteristic for the Lewis acidity of boron trihalide.
    Studies on the Two Photon Absorption Cross-sections of trans-Stilbene Derivatives
    REN Ai-Min, FENG Ji-Kang, ZHAO Xian, LIU Chun-Ling, SU Zhong-Min
    2001, 22(7):  1197-1200. 
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    The geometry, electronic structures and electronic spectra of trans-stilbene derivatives are systematically studied by PM3 and INDO/CImethods. On the basis of correct UV-Vis spectra, the position and strength of the two photon absorption cross-sections can be predicted. We deviced a program of Sum Over-States expression and calculated the nonlinear third-order optical susceptibilities and two photon absorption cross-sections by it. The influences of various substituents on two photon absorption cross-sections are discussed micromechanically.
    Kinetics and Characteristics of Electrocatalytic Oxidation of Formic Acid on Pt(110)/Sb Electrodes
    YANG Yi-Yun, ZHOU Zhi-You, WU Qi-Hui, ZHENG Ming-Sen, GU Yan-Juan, CHENG Sheng-Pei, SUN Shi-Gang
    2001, 22(7):  1201-1204. 
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    The electrochemical behavior of irreversibly adsorbed antimony on Pt(110) was studied by using cyclic voltametry. The results demonstrated that the Sbad atoms are stable on Pt(110) when the electrode potentials are below 0.45 V( vs. SCE). We illustrated that various coverages of Sbad can be easily obtained by controlling the number of potential cycling and the upper limit of potential scan. It was found that the dissociative adsorption of formic acid was inhibited by the presence of Sbad on Pt(110) surface. The electrocatalytic effects of Sbad toward HCOOHelectrooxidation is demonstrated by the negative shift of oxidation potential(about 0.35 V) and the enhancement of oxidation current. The maximum current density was measured for a Sb coverage of 0.126. Based on methods developed in our previous papers, the kinetics of HCOOHelectrooxidation on Pt(110)/Sb electrodes of different θSb has been studied, and both the rate constant k f and transfer coefficient β were determined quantitatively.
    Thermodynamic Studies on the Functionalized Substituted Dioxotetraamine Macrocyclic Super-molecular Met al Complexes in the Solution
    SU Xun-Cheng, LIN Hua-Kuan, ZHU Shou-Rong, SUN Hong-Wei, YANG Yi, CHEN Rong-Ti
    2001, 22(7):  1205-1208. 
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    New C-functionalized dioxotetraamine macrocycles, which contained two independent chelating groups, were synthesized and characterized. At (25.0±0.1) ℃, I =0.1 mol/L NaNO3, the thermodynamic properties of such supramolecular coordination compounds formed by the ligand with met al ions in aqueous solution were studied by pHtitrations and structures of coordination species were also suggested.
    Energy-saving Nonequilibrium Thermodynamic Analysis for Distillation Mathematical Model Development
    LIU Qing-Lin, LI Peng, ZHANG Zhi-Bing
    2001, 22(7):  1209-1212. 
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    Ageneral thermodynamic model was presented by analyzing distillation processes. The mass transfer in these processes was assumed in an irreversible thermodynamic state during the model development. The simulated results showed that this model could be applied not only to analyzing entropy generation in distillation processes, but also to compare the effects of the tray parameters on the entropy generation in a column, with which energy-saving distillation tower can thus be designed and the distillation operation can be controlled in an optimal mode.
    Pervaporation Dehydration of Alcohol with Polyelectrolyte Membrane
    ZHOU Zhi-Jun, CHEN Huan-Lin, LIU Mo-E, ZHANG Ying
    2001, 22(7):  1213-1215. 
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    Polyelectrolytes have a high hydrophilicity and can be used in pervaporation(PV) dehydration of alcohol. Chitosan(CS) used as polycation polysaccharide and carboxymethyl cellulose(CMC) used as polyanion polysaccharide were chosen as PVmembrane materials. CSmembrane cross-linked with oxalic acid or citric acid and CS-CMCpolyelectrolyte membrane were prepared. The results showed that the polyelectrolyte membranes had an excellent PVperformance for alcohol dehydration. For example, when the separation factor gone up to 2300, the total flux of CS-CMCpolyelectrolyte membrane was above 800 g/(m2·h) in95% EtOHand at 72 ℃. The nature and content of cross-linking agents affected the separation properties of cross-linked CSmembrane. The total flux of the cross-linked CSmembrane increased with operating temperature increasing and corresponded to the Arrhenius equation.
    Site-selective Assembly of Gold Nanoparticles on Silicon Using AFM Nano-oxidation Technique
    LI Qi-Guang, ZHENG Ji-Wen, LIU Zhong-Fan
    2001, 22(7):  1216-1218. 
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    Patterned nanoparticle arrays on solid surface have drawn much attention because of their potential for fabricating nanoelectronic devices. Here, we report a novel method to realize the site selective assembly of gold nano-particles on silicon, which combines the AFMnano-oxidation technique and wet chemical assembly technique. Nanosized oxide dots were generated by AFM nano-oxidation on OTS-covered silicon, followed by modification of APTMSmonolayer on the oxide dots. Because of the specific electrostatic attraction between gold nanoparticles and the amino terminated APTMSmonolayers, gold nanoparticles were only deposited on the oxidized regions. With this approach, we have successfully fabricated site-selective gold nanoparticle assemblies.
    The Oxidative Carbonylation of Aniline and Its Derivatives in the Presence of Resin Supported Gold
    SHI Feng, DENG You-Quan, SIMA Tian-Long, GONG Cheng-Ke
    2001, 22(7):  1219-1221. 
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    Novel resin supported gold catalysts were developed for the synthesis of carbamates by oxidative carbonylation of aniline and its derivatives. At 175 ℃ and 5.0 MPa, the oxidative carbonylation of aniline to the corresponding carbamates over these catalysts could be proceeded with a high conversion(96%), selectivity(99%) and 532 for TOFwas achieved. The resin supported gold castalyst would be reusable and the catalytic performance was much better than that of the resin supported Pd catalyst.
    STM Thermochemical Hole Burning Memory——Influence of Pulse Voltage and Duration on Hole Size
    LEI Xiao-Jun, CHEN Hai-Feng, LIU Zhong-Fan 
    2001, 22(7):  1222-1224. 
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    Recently we reported STM THB(Thermochemical Hole Burning) Data Storage. Here we study the influence of pulse voltage and duration on hole size. It is demonstrated that with the increase of pulse voltage and duration, the hole size increases correspondingly. Furthermore, theoretical analysis was conducted, which was successfully used to interpret our experimental results.
    Studies on Molecule-Exchanging Energy on Surface of Binary Surfactant Aqueous Solutions with Dimensional Crystal Model
    WANG Zheng-Wu, LI Gan-Zuo, MU Jian-Hai, GUAN Da-Ren
    2001, 22(7):  1225-1227. 
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    The relationship between activity coefficient and molecule-exchanging energy of surfactants in the surface monolayer of binary surfactant aqueous solutions has been deduced with the help of two-dimensional crystal model. The results show the relationship between the synergism of surfactants and the molecule-exchanging energy. Through the parameter of molecule interaction( βs), the value of the molecule-exchanging energy can be obtained by equation ε =2.3×10-24 βs T that has been examined with six typical surfactant systems.
    Cd2+ Ions Induced Conformation Change of DNA
    CHEN Xia, YANG Wen-Sheng, JIN Jian, XU Li, YANG Bai-Quan, JIANG Lin, LI Tie-Jin, Chen-Xi
    2001, 22(7):  1228-1229. 
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    Interactions between Cd 2+ ions and salmon sperm DNAwere investigated via UV-Vis, Circular Dichroism(CD) and FT-Raman spectroscopies. The experimental results show that Cd 2+ ions can coordinate with the phosphate groups of DNAand thus induce conformation changes of the DNAfrom Bto Atype.
    Studies on Electrochemical Behavior of Fe(Ⅱ)-EDTA Cleaving DNA on HMDE
    LI Mei-Xian, LI Nan-Qiang 
    2001, 22(7):  1230-1232. 
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    Electrochemical behavior of Fe(Ⅱ)-EDTAcleaving DNAon hanging mercury drop electrode(HMDE) was studied. It was found that the changes in the DNAstructure due to Fe(Ⅱ)-EDTAbreaking DNAresult in the increasing of a reduction peak current of DNAon HMDE, indicating that the electrochemical methods are hopeful to be used as an auxiliary means for probing changes in the DNAstructure. Furthermore, the standard rate constant of the surface reaction k s was determined as 0.59 s-1.
    Allyl Containing Iron Post-Met allocene Catalyst for Ethylene Polymerization
    LIU Chang-Kun, JIN Guo-Xin 
    2001, 22(7):  1233-1236. 
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    Tridentate ligand[(2,6-ArN[CDS1]C(Me))2C5H3N](Ar=4-allyl-2,6-( i-Pr)2C6H3)((Ar=4-allyl-2,6-( i-Pr)2C6H3)(4)which contains allyl groups on each aryl ring was ready prepared and reacted with FeCl2·4H2Oto give the precatalyst [(2,6-ArN[CDS1]C(CH3))2C5H3N]. FeCl2(FeCl2(5). Compounds 2-5 were characterized by 1H NMR, EI MS,and IR. The complex 5 which was actived by methylaluminoxane(MAO) exhibits high activity for ethylene polymerization[1.9×106 g pE·(mol Fe·h)-1 at 0℃]. It was showed that the activity was decreased with increasing temperature and the polymer product was highly linear PEwith M η varing from 50000 to 260000.
    Ultrasonic Induced Microemulsion Polymerization of MMA
    LIAO Yong-Qin, WANG Qi, WANG Liang-Wen
    2001, 22(7):  1237-1240. 
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    In this work, ultrasonic induced microemulsion polymerization of MMAwas successfully performed and the monomer conversion reached about 90% in 40 min. TEMobservation showed that the average diameter of PMMAlatex was 365 nm with a narrow distribution. Several influencing factors such as power output, surfactant, co emulsifier, monomer and chemical initiator were investigated detailedly from the view of formation of microemulsion and the growth of latex by spectraphotometry.
    A New Protein Lattice Model
    ZHANG Lin-Xi, ZHAO De-Lu
    2001, 22(7):  1241-1243. 
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    Anew protein lattice model basing on the bond fluctuation model is performed in this paper. Through investigation of two-dimensional protein structure using our lattice model, we find that our two-dimensional protein chains have more contacts. The conformations Ω0 may be expressed as Ω0N, here Nis chain length and γ =4768, and the average compactness < ρ(N) > is close to 0.31-0.32. For the given HPsequences, our protein lattices have lower ground state energies. Comparisons with two-dimensional square lattice model are also made.
    Reactive Compatibilization of Nylon6/Polycarbonate Blends by Addition of PP-g-(GMA-co-St)
    LI Zhi-Jun, GUO Bao-Hua, HU Ping, XIE Xu-Ming
    2001, 22(7):  1244-1248. 
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    The glycidyl methacrylate(GMA) and styrene(St) multi monomers melt grafted PP, PP-g-(GMA-co-St), was used as a reactive compatibilizer of PA6/PCblends in this study. The effect of the addition of PP-g-(GMA-co-St) on compatibility of the blends was investigated. It was found that the addition of PP-g-(GMA-co-St) greatly reduced the MFRvalues of the PA6/PC, implying enhanced compatibility between PA6 and PCin the presence of the PP-g-(GMA-co-St). The phase morphologies of the blends with increasing content of PP-g-(GMA-co-St) were observed by SEM. The particle size of PCdecreased with increasing content of PP-g-(GMA-co-St) in the blend. Much finer dispersion of discrete polycarbonate phase with average domain size 0.2 μm was reached when the content of the PP-g-(GMA-co-St) was 10%(PA6/PC, mass ratio 72/28). This should be due to the formation of the PA6 PP PCcopolymer by chemical reactions between GMAin PP-g-(GMA-co-St) and the terminal amino or carboxylic groups of PA6 and between GMAin PP-g-(GMA-co-St) and terminal -OHgroup of PCduring the melt extrusion process. The formation of PA6 PP PCcopolymer is also characterized by FTIR. The mechanical properties of the PA6/PCblends, particularly the Izod impactstrength and elongation at break were markedly improved by addition of a small amount of PP-g-(GMA-co-St). Itshould be noted that tensile strength of the PA6/PC/PP-g-(GMA-co-St) was also kept with increasing PP-g-(GMA-co-St) content. The PA6/PCblends with balanced mechanical properties can be obtained by addition of PP-g-(GMA-co-St).
    Real-time Kinetics Study on the Infrared Laser-induced Photopolymerization of TMPTA
    ZHANG Shi-Hai, LI Bin, TANG Li-Ming, WANG Xiao-Gong, YANG Rui, ZHOU Qi-Xiang 
    2001, 22(7):  1249-1253. 
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    The infrared laser induced photopolymerization kinetics of TMPTA, with a novel cationic cyanine dye borate complex(CBC), 1,3,3,1',3',3'-hexamethyl-11-chloro-10,12-propyleneindo-tricarbocyanine triphenylbutyl borate as photoinitiator, was investigated by Real-Time FTIR(RTFTIR) in this paper. The CBCadopted here has maximum absorption wavelength λmax at 790 nm(in TMPTAphotopolymerization sample). The photopolymerization system consisted of equal weight of a monomer (trimethylolpropanetriacrylate, TMPTA), a binder(AA/MMA/St/BAcopolymer), and different content of CBC. The double bond conversion( Y ) was determined from the drop of the absorption at 1620 and 1635 cm-1 in FTIRspectra and was continuously monitored by RTFTIRduring laser irradiation. Yincreased rapidly in the first 10 seconds and reached 37% for laser irradiation power of 17.0 mW/cm2, CBCcontent of 2.0% and sample thickness of 20 μm. Higher Yand polymerization rate( Rp) could be achieved by increasing the laser power or decreasing the sample thickness. Furthermore, there existed a critical content for CBC, below which the increasing of CBCconcentration would improve Yand Rp. Higher CBCcontent over the critical value would lead to the "filter effect", which prevents the laser beam from penetrating into the deep layer of the sample, and then deteriorates the photopolymerization. The quantum photopolymerization yield of this system was 41.8 mol/einstein.
    A Novel Macroscopic Pattern Formation During Volume Phase Transition of Polymeric Hydrogel
    JI Shi-Chen, DING Jian-Dong 
    2001, 22(7):  1254-1255. 
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    Pattern formation in polymeric hydrogel associated with volume phase transition was observed in strong gel shrinking. Chemically cross linked poly(sodium acrylate/acrylamide) gel was prepared and shaped by capillary. The gel cylinder was suddenly dipped into acetone or into an acid aqueous solution. The former exhibited bamboo-like pattern, similar to the report in the literature. But a novel pattern, gel helix or gel spring, was found in the latter case. Macroscopic patterns only occurred in a strong gel collapse, and nothing was found in a step by step volume shrinking. The helix is with period between 0.1 to 1 mm and formed within 100 second. Both right hand sense and left hand sense could be obtained. Once formed, the gel helix cannot be recovered by re swelling in basic solution. Surface crack and its helical growth were observed and could account for the formation of gel helix preliminarily.
    Purification and Characterization of Human Immunodeficiency virus Type2 External Glycoprotein Expressed in Pichia Pastoris
    ZHANG Ying-Jiu, JIN Ning-Yi, WANG Hong-Wei, SHEN Jia-Cong
    2001, 22(7):  1256-1258. 
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    Expression conditions of human immunodeficiency virus type 2 external glycoprotein gp105 in the recombinant Pichia Pastoris strain were optimized via orthogonal test of some factors such as the rate of aeration, the inductive duration, the initial pHand the concentration of methanol. The results from tests of between-subjects effects showed that the most important parameter for efficient expression of gp105 in recombinant Pichia Pastoris strain is adequate aeration during methanol induction, and the optimum inductive condition for gp105 expression was: more than 80% aeration, 3 days for induction, th einitial pHof 6.0-7.0, the final methanol concentration of 1.0%-1.5%. With this condition, the expressed gp105 was secreted into fermentation broth and reached a ield of 30%, approximately 200 mg/L. Expressed gp105 was isolated and purified by sating out and Sephadex G-100 chromatography and the yield of gp105 was 40%. gp105 was purified to electrophoretic purity and its pIwas about 5.0 by SDS-PAGEand isoelectrofocusing. Its N-terminal amino acid was arginine by Dansyl-Cl and the result indicated that expressed gp105 was secreted and cleavaged correctly. The results from ELISAdemonstrated that the purifiec gp105 showed good reactiongenicity and antigenic specificity.
    Studies on Syndiospecific Polymerization of Styrene Catalyzed by CpTiCl2(OR)/MAO System
    MA Hai-Yan, ZHANG Yue, CHEN Bin, HUANG Ji-Ling, QIAN Yan-Long 
    2001, 22(7):  1259-1261. 
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    Five new alkoxyl substituted half sandwich complexes CpTiCl2(OR), R=methoxylethyl(1), methoxylpropyl(2), methoxylisopropyl(3), o methoxylphenyl(4), tetrahydrofurfuryl(5), were synthesized, characterized and tested as catalyst precursors for the syndiospecific polymerization of styrene. When activated with methylaluminoxane(MAO), the new precursors 1-5 exhibited high catalytic activity for the syndiospecific polymerization of styrene and were more active than CpTiCl3. The differentstructures of alkoxyl ligands affected the activity slightly. When the polymerization was carried in bulk, all the five precursors exhibited high catalytic activity even at low ratio of c (Al)/ c (Ti)=300, the s PS% of the polymer produced by alkoxyl substituted complexes was much higher than that of CpTiCl3. The polymerization temperature of 70 ℃ was more suitable for this kind of complexes. The existence of the additional oxygen atom in the alkoxyl ligands stabilized the active species at the higher temperature.
    The Solvation and Desolvation Process in the Course of Coil-globule Transition of Aqueous Poly( N-isopropylacrylamide) Solution
    CHENG Rong-Shi, YANG Hu, YAN Xiao-Hu, WANG Zhi-Liu, LI Li
    2001, 22(7):  1262-1264. 
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    The temperature dependence of the specific refractive index increment d n /d c of aqueous poly( N-isopropylacrylamide) solution in the range of 20 ℃ to 35 ℃ were determined by a differential refractometer. The measured d n /d c of the solution decreases regularly and smoothly with increasing temperature until to the specific coil globule transition temperature of PNIPAM (around 32 ℃) and afterwards it increases with increasing temperature on the contrary. This extraordinary phenomenon is successfully explained and treated by a quantitative theory in terms of accompanying solvation desolvation process in the course of coil-globule transition of the polymer chain in solution.
    Binding of Ionic Derivative of Pyrene to Strong Polyelectrolyte
    WANG Chao-Yang, SUN Qi-Long, TONG Zhen, LIU Xin-Xing, ZENG Fang, GAO Feng
    2001, 22(7):  1265-1267. 
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    Binding of pyrene probe cation of 1-pyrenemethylamine hydrochloride(PyMeAH+) to sulfonate polyelectrolyte PAMPSin aqueous solution was investigated by the relative fluorescent intensity IE/ IM of the excimer to monomer. The saturation amount of repeat unit AMPSfor the polyelectrolyte bound to one PyMeAH+ ion was about 2.5 estimated from the maximum on the curve of IE/ IMvs. the probe concentrations. The increase of the ionic strength of the solution by adding salt or excess alkali ions of 10-4 mol/Lgreatly reduced the IE/ IMvalue. This factsuggested that the probe cation PyMeAH+ form a loose ion pair with the sulfonate anion on the polyelectrolyte.
    Thermal Evolution Behavior of Solution-cast Film of PPO/PS Blends
    PAN Yan, FU Wei-Wen, XUE Feng, CHENG Rong-Shi, LUO Yuan-Fang, GU Ju
    2001, 22(7):  1268-1270. 
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    Thermal evolution behavior of solution-cast film of Poly(2,6-dimethyl 1,4-phenylene oxide)(PPO)/polystyrene(PS) blend was investigated by conventional and modulated differential scanning calorimetry. It was found that the original PPO/PSblend film is actually composed by a crystalline PPOphase and a non crystalline compatible PPO-PSphase. The phase-segregated structure state(A) will evolve to non-crystalline homogenous structure(B) by subsequent thermal treatment. The effect of annealing temperature on the evolution process was discussed.
    Preparation of LLDPE with Dual-functional Catalytic System Ti(OBu-n)4/AlEt3-[Me2SiNtBuInd]ZrCl2/MAO
    LIU Zhong-Yang, WANG Jun, LI Xiu-Hua, HE Da-Wei, HU You-Liang, Yan-Wei-Dong
    2001, 22(7):  1271-1273. 
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    This paper reports a new kind catalytic system to produce linear low density polyethylene(LLDPE) from ethylene alone in a single reactor by combining the ability of Ti(OBu-n )4/AlEt3 to produce 1-butene with the ability of [Me2SiNt BuInd]ZrCl2/MAOto copolymerize ethylene with 1 butene. It was found that the dual functional catalytic system has high activity and get the good polymer with density ranging from 0.91-0.95 g/cm3 in ethylene polymerization.