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    24 August 1998, Volume 19 Issue 8
    Articles
    Non-framework Cation Locations in Zeolite Beta
    WANG Ying-Xia, MENG Xian-Ping, LI Neng, ZHANG Wan-Jing, LIN Bing-Xiong, LIU Xi-Yao
    1998, 19(8):  1185-1190. 
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    On the basis of fundamental principle of structural chemistry and through atom distance-least-square refinement, the non-framework cation locations in zeolite beta were determined, which was then confirmed by X-ray scattering experiment analysis using Cu2+as the probe ion. The result shows that in the stack faulting structure of zeolite beta, the non framework cation positions lie in the 12-membered ring intersecting channels, near the double six memberedring of building unit Ⅰ and coordinated by six framework oxygen atoms. These cation positions belong to six kinds of different crystallographic sites: two sets of equivalent positions in polytype A, one set in polytype Band three sets in polytype C. The geometric circumstances and the coordination state around the cations are very similar to each other and the average coordination bonding distances of M_O are almost equal, so all the non-framework cations in zeolite beta act as one type of cations. Correspondingly, zeolite Hβ has only one kind of Brnsted acid sites, which was also proved by the NH3-TPD curves of the samples. The cations with this kind of distribution can contact with reagent molecules easily and efficiently. Therefore it can be conclude that Hβ is a kind of acid catalyst with a high activity and excellent selectivity, and M-zeolite beta may become a potential redox catalyst.
    Synthesis and Properties of CdS/TiO2Coupled Semiconductor Nanoparticles
    HAO En-Cai, SUN Yi-Peng, YANG Bai, SHEN Jia-Cong
    1998, 19(8):  1191-1194. 
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    A new kind of preparation method of CdS/TiO2coupled semiconductor nanoparticle in aqueous solution is described, in which CdSis in-situ formed on the surface of TiO2.Furthermore, coupling of the two semiconductor particles via the bifunctional thiols offers an opportunity to sensitize TiO2with a large bandgap and energetically low-lying conduction band by CdS with a small bandgap and an energetically high lying conduction band. IR spectra were used to follow the formation process of this coupled nanoparticles. UV-V is spectra illustrated well the stability effect of TiO2on the formation of CdS nanoparticles. The quenching of CdSemission indicated that there were an effective charge separation between dissimilar semiconductor particles.
    Hydrothermal Synthesis and Mössbauer Spectra Study of Hydrogarnet Sr3Fe2(OH)12
    LI Guang-She, MAO Ya-Chun, LI Xi-Rong, ZHU Lian-Jie, FENG Shou-Hua
    1998, 19(8):  1195-1199. 
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    A single phase hydrogarnet Sr3Fe2(OH)12was synthesized from mild hydrothermal systems. For Sr3Fe2(OH)12, the hydroxyl groups of Sr_OH dodecahedra were decomposed in the form of four water molecules around 573 K. On heating Sr-Fe hydrogarnet in air or oxygen, an oxidation process from Fe(Ⅲ) to Fe(Ⅳ) takes place. Valence variation of the framework ions Fe(Ⅲ) determined the decomposition process and the structural types of the products. Two octahedra of Fe(OH)6in Sr-Fe hydrogarnet were first detected by combining Mössbauer spectra and XPS.
    Synthesis and Properties of Rare Earth Molybdosilicic Heteropoly Blues Substituted by Cobalt
    LIU Jie, Wang-En-Bo, WANG Zuo-Ping, HU Chang-Wen
    1998, 19(8):  1200-1204. 
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    Rare earth molybdosilicic heteropoly blues substituted by cobalt, Ln2H2[SiMo11Co·(H2O)O39]·nH2O(Ln=La, Ce, Pr, Nd, Sm, Gd) have been prepared and systematically characterized by IR, UV, CV, TG DTA, XPS, 29SiNMR, polarography and magnetic susceptibility. Based on the experimental results, it is reported that the reduced products(heteropoly blues) slightly change their structures compared with unreduced compounds. Co2+and Ln3+do not change in the reduced processes.
    Synthesis and Crystal Structure of Binuclear Copper(I) Complex Through Reduction Reaction
    YANG Rui-Na, ZHANG Shao-Wen, SUN Yu-An, DUAN Zheng, JIN Dou-Man, LUO Bao-Sheng
    1998, 19(8):  1205-1207. 
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    Binuclear copper(Ⅰ) complex [Cu2(dppm)2(Py)2(NO3)](NO3)·CH3OH(2), Py=pyridine, dppm=bi(diphenylphosphine)methane has been synthesized by ligand reduction of cupric nitrate with dppm and characterized by means of specific elemental analyses, molecular weight determination, 31PNMR and electronic conductivity measurement. The X-ray crystal structure of complex (2) shows that dppm coordinates as a bridging bidentate ligand to the two Cu(Ⅰ) atoms, and two NO3behave as a bidentate ligand and an outer sphere respectively in the newly prepared binuclear copper(Ⅰ) complex. The crystal is monoclinic, space group P21with unit cell parameters a=1.3650(4) nm, c=1.3653(2) nm, b=1.5970(7) nm; β=105.4(2)°, Z=2, V=2.8689nm3, F(000)=1252, Dc=1.373 g.cm-3, μ=90 cm-1, R=0.026, Rw=0.028.
    A Study of the Ternary System of Zn(ClO4)2-BAPHDCA-H2O at 30℃ and the Preparation and Characterization of the Zn(BAPHDCA)(ClO4)2·2H2O
    CUI Bin, TANG Zong-Xun, GUO Zhi-Zhen, CHEN Kai-Xun
    1998, 19(8):  1208-1210. 
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    The solubilities and the refractive indexes of the saturated solutions of the titled system at 30 ℃ have been studied and the corresponding equilibrium diagram and refractive index diagram were constructed, both solubility curves and refractive index curves of the system consist of three branches, corresponding to BAPHDCA, Zn(BAPHDCA)(ClO4)2·2H2O and Zn(ClO4)2·6H2O, respectively. The Zn(BAPHDCA)(ClO4)2·2H2O is a new compound, which was characterized by chemical and elemental analysis, IRspectra and thermoanalysis.
    Studies of Synthesis and Magnetic Resonance of Lanthanide Complexes with Noncyclic Polyether 2,4-dihydroxybenzaldehyde Schiff Base
    WU Jing, YAO Ke-Min, CHEN De-Yu, SHEN Lian-Fang, YUAN Han-Zhen
    1998, 19(8):  1211-1213. 
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    Nine new Ln(Ⅲ) complexes with a Schiff base, 2,4-dihydroxybenzylidene diglycol diamine, [Ln2(DHYDA)3(NO3)3](NO3)3· nH2O (Ln=La, Pr, Nd, n=5; Ln=Sm, Gd, Tb, Er, Yb, Y, n=6), have been synthesized. Intramolecular Hbond in free ligand, the coordination of 2-OH and the uncoordination of 4-OH group in the obtained complexes have been proved by UV, IRspectra especially by 500 MHz 1H and 12CNMRs pectra. The existence of two different structure ligands in the complexes has been suggested as well. One of the ligands acts as a bridge to connect two Ln3+. The EPR spectra of the Gd(Ⅲ) complex exhibits the "U" spectrum feature. The crystal field strength, the local symmetry around Gd3+in the complex have been discussed. The possible coordination number 10 is suggested tentatively.
    Studies on Surface Plasmon Resonace Sensor
    ZHAO Xiao-Jun, WANG Zhen, XU Han-Ying, LIANG Feng, ZHANG Han-Qi, JIN Qin-Han
    1998, 19(8):  1214-1218. 
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    Based on surface plasmon resonance(SPR), a novel optical chemical sensor was developed. Traditionally SPRsensing method was to fix wavelength and modulate angle of incidence light, which needed an expensive and complicated apparatus. The device presented here is a relatively simple and inexpensive. It was designed on the basis of fixing angle of incidence light in the range of the wavelength of 400~800 nm. The reflected light intensity is the minimum at the resonant wavelength, a smaller increase in refractive index of the analyzed solution would cause a clear shift in the SPRreflection spectra toward larger resonant wavelength. The sensitivity to refractive index changes was found to be 4.6×10-4index of refraction units at a wavelength of 575 nm. Some sample were analyzed with the sensor. The results obtained are in good agreement with those obtained with other method. Under the selected experimental conditions, the sensor has a good repeatability(RSD≤1.4).
    Effects of Microemulsion Composition on Microemulsion Electrokinetic Capillary Chromatography
    Lü Jian-De, FU Xiao-Yun, XU Xiu-Zhu
    1998, 19(8):  1219-1222. 
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    A set of wide polar aromatic analytes was separated by microemulsion electrokinetic capillary chromatography(MEEKC). The effects of microemulsion compositions, including the core phases(n-hexane, n-heptane, n-octane) alkyl chain length, the concentrations of core phase heptane, surfactant sodium dodecyl sulfate and co-surfactant n-butanol, on electrokinetic separation were studied. The results showed that the surfactant had the similar effects on the retention time of all analytes. And both core phase and co-surfactant had different effects on analytes with hydrophilic functional groups and without any hydrophilic functional group. The separation mechanism of microemulsion electrokinetic chromatography was discussed. Using microemulsion consisting of 80 mmol/L n-heptane-120 mmol/L SDS-900 mmol/L n-butanol-10 mmol/Lborate, the complete separation was obtained within 14minutes. The numbers of theoretical plate ranged 3×105-9×105per meter.
    The Kinetic Simulation Study of Laccase Catalyzed Formation and Decay of Semiquinone Radicals
    WU Xing-Guo, CAI Ru-Xiu, HUANG Hou-Ping, WANG Peng
    1998, 19(8):  1223-1226. 
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    The kinetic model is built based on the kinetic process of laccase catalyzed oxidation from 5,6-dibromo 2,3-dicyano hydraquinone to semiquinone radicals. By simulating the real kinetic curves, the mechanism regarding the formation and decay of semiquinone radicals is proposed, which provides basis for the further study on the interaction between semiquinone radicals and other biologically active substance.
    Qualitative and Quantitative Analysis of Two-way Chromatographic/Spectroscopic Data with Overlapping Peaks(Ⅱ) Annihilation of Rank and Resolution by Projection and Determination of Polycyclic Aromatic Hydrocarbons in Air-borne Particulate
    CHEN Di-Zhao, LIANG Yi-Zeng, SHEN Hai-Lin, CUI Hui, YU Ru-Qin
    1998, 19(8):  1227-1231. 
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    A new chemometric approach, annihilation of rank and resolution by projection(ARRP) has been developed in this paper. The chromatographic peaks can be directly qualified and quantified without resolution of the other chromatographic peaks. The approach has been successfully applied to the qualitative and quantitative analysis of complex real multicomponent system with PAHs phenanthrene, anthracene, fluoranthene and pyrene as desired components in air-borne paritculate.
    Separation of Cobalt, Nickel and Copper by Pre-column Derivatization Capillary Electrophoresis in Nonaqueous Medium
    LIU Bi-Feng, LIU Liang-Bin, CHENG Jie-Ke
    1998, 19(8):  1232-1235. 
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    Separation of cobalt, nickel and copper elements as their 2-(6-methyl-2-benzothiazolyazo)-5-dimethylaminophenol complexes by capillary electrophoresis in nonaqueous medium was first presented. Ethanol and N,N-dimethylformamide(DMF) were evaluated for the effect of nonaqueous solvents on electroosmotic flow. The influence of the pre column derivitization conditions, some parameters such as choice and selection of organic solvents, concentration ratio in mixed nonaqueous medium, applied voltage on the separation were also investigated. Under the optimum conditions(buffer: 40 mmol/L, pH5.0 NaAc-HAc in ethanol(50%) and DMF(50%) mixture, 30 kV, 575 nm as detection wavelength), the three ions were separated in6min successfully, and detection limits of 9.18×10-8mol/L, 2.79×10-7mol/L and 4.47×10-7mol/Lfor cobalt, nickel and copper were achieved, respectively. The theoretical plate number reached up to 3.2×105/m.
    Studies on the Transport and Enrichment of Trace Metal Ions Cd2+and Cr3+by W/O Microemulsion
    HAN Li-Xin, LI Ke-An, TONG Shen-Yang
    1998, 19(8):  1236-1238. 
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    The water-in-oil(W/O) microemulsions, which have been prepared by using the surfactant diethylhexyl sodium sulphasuccinate(AOT) and the oil solvent n-heptane, were used to transport and enrich trace metal ions Cd2+and Cr3+. The experimental results show that the two metal ions have high transport ratios(>90%) under the optimum conditions, Cd2+has high enrich times(6-7 times) and recovery ratio(100%), but Cr3+has very low enrich times(1-2 times) and recovery ratio(0%) under the given conditions of de emulsion.
    A Study of Hemoglobin at Silver Colloid by Surface Enhanced Raman Spectroscopy
    YE Bao-Xian, LIN Lin, ZHANG Wu-Ming, ZHOU Xing-Yao
    1998, 19(8):  1239-1241. 
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    The properties of Hemoglobin adsorbed on the silver colloid surface were investigated by using surface enhanced Raman spectroscopy(SERS) in the determination of oxygen-hemoglobin, deoxygen-hemoglobin and heme. The results show that the heme chromophore of oxygen-hemoglobin interacts directly with silver colloid, as a result of either its detachment from the protein matrix or denaturation from the protein. The deoxygen-hemoglobin would not release its heme at the silver colloid as normally expected.
    Paramagnetic Metal Chelates of DTPA-and EDTA-dipyridoxolester Derivatives and Their NMR T1Relaxivities in Water
    WEI Jun-Fa, ZHUO Ren-Xi
    1998, 19(8):  1242-1246. 
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    Several novel ligands of DTPAa-nd EDTA-dipyridoxolester derivatives have been synthesized by reaction of DTPA-dianhydride and EDTA-dianhydride with pyridoxol(vitamin B6) in dry DMF. Their complexes of gadoliniun, manganese and iron were prepared and the measurements of T1relaxivities in solution of water in vitro were performed with the gadolinium and the manganese complexes. The results show that all of the complexes are highly water soluble and very slightly light and air sensitive both in solid state and in solution. The T1relaxivities of the complexes, for example, gadolinium-DTPA-dipyridoxolester, GdDTPA-BPN, and manganese-EDTA-dipyridoxolester, MnEDTA-BPN, were determined to be 5.5 and 3.1 L·mmol-1·s-1, respectively. These can be compared to the values of the corresponding complexes of their parent ligands, GdDTPA2-and MnEDTA2-, indicating the complexes are potentially useful contrast agents for magnetic resonance imaging.
    Studies on Schiff Bases Possessing Hormone Activity(Ⅱ) Synthesis and Activity on Schiff Bases of Triazole
    WANG Yan-Gang, CAO Lei, YANG Jun, YE Wen-Fa, ZHOU Qing-Chun
    1998, 19(8):  1247-1250. 
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    Eleven new Schiff bases of triazole have been synthesized for the first time. Their physical constants, UV, IR, 1HNMR, elementary analysis and biological activity were originally studied. It is found from the results of biological activity tests that nine compounds have a remarkable activity on plant growth regulation. Compounds Ⅰb, Ⅰc, Ⅰeand Ⅱehave a good activity on cytokinin, compounds Ⅰa, Ⅰe, Ⅰi, Ⅰjand Ⅱahave a excellent activity on growth of root.
    The Relationship Between the Bridging Alkyl Group and Electrochemical Behavior of Some Biferrocenyl Alkanes
    LIU Wan-Yi, YUAN Yao-Feng, ZHANG Ling-Yun, WANG Ji-Tao
    1998, 19(8):  1251-1255. 
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    The cyclic voltammetric behavior of some alkyl-bridged biferrocene compounds are reported. It was found that the stable conformation is the decisive factor influencing their electrochemical properties. The larger the angle between the two ferrocenyl groups and the bridge carbon deviates from 109°28', the greater the Δ Epvalue bocomes. Besides, the electrochemical behavior of some 6-acyl, 6,6'-diacyl alkyl bridged biferrocene derivatives are investigated and the factors affecting their electrochemical behavior are also discussed. Acyl group exerts an electron withdrawing effect on the ferrocenyl moieties, which makes them more difficult to be oxidized than their parent compound.
    Asymmetric Synthesis of Optically Active 2-Ethyl-1-Amino-cyclopropanecarboxylic Acid via Pianone Ketimine
    SU Gui-Fa, Philippe Dorizon, Jean Ollivier, Jacques Salaün
    1998, 19(8):  1256-1261. 
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    Optically active cyclopropanes(4) were obtained by using 2-hydroxypinan-3-one 1 as a chiral auxiliary, condensed with aminoacetonitrile to form a chiral ketimine 2 followed by Pd(0) catalyzed tandem alkylation and SN'cyclisation of 1,4-dichlorobut-2-ene 3 with chiral ketimine 2. The yields are 69% and the diastereoselectivities of reaction are 100%. After the selective reduction of ethenyl group of 4, then by simple acid hydrolysis, optically active-2-ethyl 1-amino-cyclopropanecarboxylic acid 6 could be obtained, the e.e. value of 6 is 33%.
    The Synthesis of Two Series Novel Sulfur-containing Chiral Macrocyclic Ligands
    ZHANG Xiao-Ling, LI Xing-Shu, XIE Ru-Gang
    1998, 19(8):  1262-1266. 
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    In this paper, we report that two series of novel optically active sulfur containing macrocyclic ligands have been synthesized by using L-cysteine as the source of chirality. The synthetic method is in the following: in the presence of NaHCO3, L-cysteine reacts with dibromoalkane to form bridged bis-amino acids under a very mild condition, then, are transformed to the bis esters and cyclized with bis acid chlorides to give the targets 3a-3e. The other series are macrocyclic ligands with sulfur containing pendant. Firstly, L-cysteine reacts with PhCH2Cl to give β-benzylthio-L-alanine, and then it is reduced to 2-amino-3-benzylthio-propanol by BH3·THF. The amino alcohol reacts with bis-toluene-p-sulphonate of diethylene glycol to give the diamine 4f. The synthesis of 4g-4h is just like that of 4f.The cyclization of 4f-4h with 2,6-pyridinedicarbonyl dichloride gives the macrocyclic ligands 5f-5h. The structures proposed for these novel macrocycles are consistent with the data obtained from their 1HNMR, MS and IRspectra and elemental analysis.
    Studies on Ca2+Binding of Thermostable α-Amylase
    ZHAO Ying, FEI Xiao-Fang, ZHENG Yu-Juan, DONG Qing-Chu, WANG Jie, CHENG Gang
    1998, 19(8):  1267-1270. 
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    It was determined that α-amylase contained ten Ca2+.Resulted from the study of stability and activity of Ca2+-free α-amylase after adding Ca2+, the first eight Ca2+related to catalytic function of the enzyme, the other two Ca2+made the structure of enzyme stable. According to the CDand fluorescence spectra of α-amylase at room temperature, no significant change of the enzyme structure was observed. Furthermore, according to the CDspectra of α-amylase after adding Ca2+(heated at 90 ℃ for 15 min), some α-helix structures of the enzyme still existed. Fluorescence spectra of α-amylase at 90 ℃ for 15 min also showed that enzyme kept the conformation maximum stability when the Ca2+-free α-amylase was binding to 10 Ca2+.All the results indicated that the dependence of enzyme conformation on Ca2+was low.
    Studies on Total Synthesis of Methyl Ether of Isoamericanol A, Methyl Ether of Isoamericanin A and (±)-3-Methoxy-3',7-epoxy-8,4'- oxyneoligna-4,9,9'-triol
    SHE Xue-Gong, GAN Yong-Hong, WU Tong-Xing, PAN Xin-Fu
    1998, 19(8):  1271-1273. 
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    Methyl ether of isoamericanol A, methyl ether of isoamericanin A and (±)-3-methoxy-3',7-epoxy-8,4'-oxyneoligna-4,9,9'-triol have been synthesized with coupling reaction as a key step.
    Studies on the Synthesis and Biological Activity of N-Aryl-5-aryl-2-furoamides and N-(5-Aryl)-2-furoyl-N′-Aryloxyacetylhydrazines
    WANG Xi-Cun, CHEN Ji-Chou, WANG Xiu-Chu
    1998, 19(8):  1274-1276. 
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    A series of new N-aryl-5-aryl-2-furoamides and N-5-aryl-2-furoyl-N′-aryloxyacetylhydrazines were synthesized by liquid liquid phase transfer catalysis. Their structures were confirmed by elementary analysis, IRspectra and 1HNMR. Compared with classical methods, this method has the advantages of simple operation, mild conditions and high yields. The promoting effects of these new compounds on wheat growth were tested preliminary.
    Synthysis of para-Substituted 1,2-Diphenylethene and Its Asymmetric Dihydroxylation
    ZHANG Sheng-Yong, SUN Xiao-Li, LI Xiao-Ye
    1998, 19(8):  1277-1279. 
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    The para-substituted (E)-stilbenes 2a-2e were prepared respectively by Wittig reaction and nucleophilic substitution in 59%~80% yields. The asymmetric dihydroxylation was carried out by the modified Sharpless method. The amount of OsO4was increased to 1%(mole ratio) and the amount of ligand to 5%(mole ratio). All asymmetric dihydroxylation was performed at 0 ℃, affording the corresponding chiral 1,2-diol in 77%~87% yield with 82%~93% e.e..
    Synthesis and Bioactivity or Substituted Benzaldehyde Oxime Carboxylate(Ⅱ) Synthesis and Bioactivity of α-Alkylthio Substituted Benzaldehyde Oxime Carboxylate
    HUANG Run-Qiu, SUN Jian-Yu, LI Hui-Ying, CHAI You-Xin
    1998, 19(8):  1280-1282. 
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    In this paper, nineteen new α-substituted benzaldehyde oxime carboxylates were synthesized. Their structures were confirmed by elementary analysis and 1HNMR. The preliminary bioassays indicated that some compounds showed a high insecticide activity and high antiviral activity.
    Electronic Structure and Biodegradability of Azo-dyes Molecule(Ⅰ) Effect of the Charge Distribution on the Reduction Breakdown of Azo-bond
    ZHANG Xiao-Yi, LAN Wei, PAN Yu-Sheng, REN Da-Gong, DU Guo-You, DUAN Zheng-Kun, LIU Zhi-Chun, YAO Sha
    1998, 19(8):  1283-1287. 
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    The electronic structure of a series of azo-dye molecules was calculated by MNDOmethod in this paper. It was found that the biodegradation of azo-bond was greatly affected by the symmetry of the charges distribution in molecular structure in comparison with the anaerobic breakdown experimental results, then the electronic structure biodegradability relationship was described by means of LUMOlp(lowest unoccupied molecular orbit with the characteristics of lone electron pair) and molecular dipole moment.
    The Kinetics Study on Dismutation of Superoxide Catalyzed by Cu(Ser)2and Cu(Gly-Gly)2by Using Stopped-flow Method
    XIE Ying, JIN Qiu, LI Da-Zhen, GAO Pan-Liang, ZI Jun-Qing
    1998, 19(8):  1288-1291. 
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    In order to estimate the activities of natural SOD and the analogue of SOD on dynamics, the kinetics of Cu(Ser)2and Cu(Gly-Gly)2catalyzed the dismutation of superoxide were studied at pH=7.8 by using stopped-flow method. The rate constants kcat, reaction order n, activation energy Eaand Arrhenius equation were obtained. the reaction mechanism was probed, and it was proved that the first step of the reaction was the determining step.
    The Relationship Between Framework Topological Structures and Lattice Energies of Aluminophosphate Molecular Sieves
    XU Wen-Guo, LI Bao-Zong, QIU Shi-Lun, PANG Wen-Qin , XU Ru-Ren
    1998, 19(8):  1292-1295. 
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    By using computer modelling based on the lattice energy minimization technique, the lattice energies of nineteen types of aluminophosphate molecular sieves have been calculated. The studies on the relationship between the topological structures of these molecular sieves and framework lattice energies have been performed by monovariate, multivariate regression analysis and standard back-propagation(BP) algorithm of artifical neural networks. The predicted results by using multiregression analysis are in agreement with the calculated lattice energies and show a good multivariate linear relationship between the coordination sequences(N2~N3) of these molecular sieves and framework lattice energies. The lattice energies of ten types of the topological structures have been predicted.
    Phase Diagram, Structure and Fluorescence Spectra of CsxRb1-xYbI3System
    XU Min, WANG Shi-Hua, WANG Mei-Tian, LIU Chun-Sheng
    1998, 19(8):  1296-1299. 
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    The CsxRb1-xYbI3system in the composition 0≤ x ≤1 was synthesized and the phase diagram of CsxRb1-xYbI3was measured by the different thermal analyses(DTA). This phase diagram was completed and certified by the X-ray powder diffraction and flourescent spectra. This system is a limited solid solution with peritectic reaction and eutectoid reaction. The temperature of peritectic point and eutectoid point are 627 ℃ and 371 ℃ respectively. There are three kinds of solid solution in the system: a RbYbI 3 type solid solution and a high temperature phase of RbYbI3type solid solution when 0≤ x ≤0.5 and a CsYbI3type solid solution when0.75≤ x ≤1.0.
    Partial Oxidation of Methane to Syngas over Pt/Al2O3and Pt/CeO2/Al2O3
    YAN Qian-Gu, GAO Li-Zhen, YUAN Song-Yue, YU Zuo-Long
    1998, 19(8):  1300-1303. 
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    The catalytic oxidation of methane to syngas has been carried out over Pt/Al2O3and Pt/CeO2/Al2O3.It was found that the catalysts with ceria exhibit a higher activity and selectivity than those without ceria. The catalysts were characterized by means of TPR, TPD, SEM EDX and XRD. There is a strong interaction between ceria and platinum under the reaction condition, which increase the dispersion of platinum over catalysts, preventing the sinter of the Pt particles. As a result of the synergistic effect between Pt and ceria, the activity of Pt/Al2O3for combustion reaction was suppressed, the activity and selectivity for partial oxidation were improved greatly. Another role of ceria in the catalyst is the enhancing of the WGSR, which leads to the increase of the selectivity of catalyst for hydrogen and accelerating the equilibrium of the reaction.
    Crystal Structure and Colossal Magnetoresistance of Self doped La1-δ Mn1-δ O3Compounds
    XIANYU Wen-Xu, QIAN Zheng-Nan, LI Bao-He, WANG Xiang-Qun, ZHAO Tie-Song
    1998, 19(8):  1304-1307. 
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    La1-δ Mn1-δ O3compounds were prepared by the sol-gel technique. The effect of sintered condition on the crystal structure, magnetic property, conductivity and magnetoresistance for La1-δMn1-δO3was investigated. It was found, for the first time, that there exist two peaks in the R-T curve for the sample sintered at 1473 Kfor 24 hours.
    Interaction Energy and Force of Spherical Colloidal Particles at Moderate Potential
    GUO Ji-Zhi, LUO Gen-Xiang, WANG Hao-Ping, ZHAO Xiong-Hu
    1998, 19(8):  1308-1311. 
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    Using the definition of the effective reduced surface potential and resorting to improved Derjaguin method, we derive the formula for the interaction energy and force of identical and dissimilar spherical colloidal particles, valid up to the moderate potential. The agreement with exact numerical values is considerably improved on providing the surface potential ≤100 mV (for identical) and ≤75 mV (for dissimilar), the maximum relative errors are less than ±10%. For the identical and dissimilar spherical particles, our formula are best approximate expressions at present.
    Effects of Electrodeposition Conditions on the Structure and Surface Characteristics of Amorphous Fe-Mo Alloys
    NIU Zhen-Jiang, YAO Shi-Bing, ZHOU Shao-Min
    1998, 19(8):  1312-1316. 
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    The effects of molybdenum content in the bath, current density and temperature on the structure and surface characteristics of amorphous Fe Mo alloys electrodeposited from the bath containing FeSO4, Na2MoO4, H3Cit and NaCl (pH=3~5) were investigated by using XRD, SEM and XPS. The results show that amorphous Fe-Mo alloys can be obtained as long as the molar fraction of Mo in Mo/Mo+ Fe in the bath is larger than 50%,the applied current density larger than 25mA/cm2and the temperature of electrolyte lower than 40 ℃. The SEM observation of the microstructure of the electrodeposited Fe-Mo alloys shows that the deposits contain numerous granules and cracks. According to the results of XPS, both Fe and Mo exist in metallic state in the bulk alloys but in oxidized states on the surface of the alloys. The results indicate that Fe and Mo on the surface of the alloys are easy to react with H2O or O2in air resulting in the formation of oxide films. The corrosion resistance of the amorphous alloys in 3% NaCl solution surpasses that of pure iron.
    Catalytic Oxidation of CO at Ambient Temperature and Humidity on Au/NiO Prepared by Using Different Methods
    ZHANG Wen-Xiang, TAO Yu-Guo, JIA Ming-Jun, WU Tong-Hao, LI Xue-Mei
    1998, 19(8):  1317-1319. 
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    The activities and durability of the oxidation of COat ambient temperature and humidity on nanometer Au/NiO prepared by using different methods were studied. It was found that the activities and durability of the catalysts were greatly changed with the preparation methods and calcining temperature. Active and durable catalyst can be obtained by careful control of the preparation procedures. Among the samples tested, Au/NiO prepared by the following conditions--Na2CO3solution was added into an aqueous solution of Ni(NO3)2, HAuCl4and dodecylbenzene sulfonic acid sodium salt (DBS), the resultant precipitate was heated to 70 ℃ and washed with deionized hot water of 70 ℃, followed by drying at room temperature for 48 h, and then the precipitate was calcined at 300 ℃--showed the highest activity and durability, it was even able to oxidize CO completely at 20 ℃ in the presence of 1.8% water vapor for 27 h.
    Electrocatalytic Oxidation of Methanol at the Titanium Oxide Electrode Modified with Pt Microparticles
    YANG Hui, XUE Kuan-Hong, LU Tian-Hong
    1998, 19(8):  1320-1322. 
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    The electrocatalytic oxidation of methanol at the Titanium oxide(TiOx, x <2) film modified with Pt microparticles has been studied. The results show that the modified electrodes exhibit a significant electrocatalytic activity and good stability for the oxidation of methanol. Under the optimal conditions, the peak current density at 0.58 Vfor the oxidation of methanol in the positive-going sweep is about 526 mA/cm2at the scan rate of 5 mV/s in0.5mol/L CH3OH and 0.5 mol/L H2SO4solution and the over potential of the methanol oxidation at the modified electrode increases about 30~40 mV after 70 minutes at the current density of 100 mA/cm2and 50 mA/cm2. The enhanced electrocatalytic activity and good stability are ascribed to the high dispersion of Pt microparticles in and on the TiOx film and the synergistic effect between Pt microparticles and TiOx.
    Studies on the Langmuir Films of the Quinone Compounds with Long Alkyl Side Chains and Their Surface Potential
    HUANG Yan-Yi, GAN Liang-Bing, HUANG Chun-Hui, ZHAO Yi-Lei, ZHAI Jin, ZOU Yong-De, TAN Jun, ZHAO Xin-Sheng
    1998, 19(8):  1323-1325. 
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    The Langmuir films of three quinone (ubiquinone or plastoquinone) molecules with long alkyl side chains, 2,3-dimethyl-5-nonadecyl-1,4-quinone(1), 2,3-dimethyl-5,6-dinonadecyl-1,4-quinone(2) and 6-methyl-2,3-dimethoxyl-5-nonadecyl-1,4-quinone(3) were investigated. The surface potential isotherms of these molecules have been studied for the first time by using Kelvin probe method. The phenomena presented by the surface pressure and surface potential isotherms have been well explained theoretically. By using the semi empirical molecular orbital theory, the simulation of molecular dipole moments were calculated and the packing orientation of different molecules on the air/water interface were deduced according to the results of surface potential measurements.
    The Explaination for Thermal Lens Spectroscopy of C60
    YU Yong, ZHANG Zhen-Man, HOU Hui-Qi
    1998, 19(8):  1326-1328. 
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    The mathematical explaination for thermal lens spectroscopy of C60was indicated. The theoretical results are in agreement with the experiment ones. The theoretical model for C60′s thermal lens spectroscopy and the lifetime of C60triplet state are also given in this paper.
    The Curing Theory of AfType Free Radical Homopolymerization(Ⅰ) Distribution Function and Its Invariant Property
    WANG Hai-Jun, Lü Zhong-Yuan, HUANG Xu-Ri, LI Ze-Sheng
    1998, 19(8):  1329-1334. 
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    By means of the polymer statistical theory, the sol fraction, gelation condition for the Af type free radical homopolymerization reaction are deduced. Furthermore, the number fraction distribution is obtained by means of the Lagrange expansion technique and the invariant property of this distribution is revealed. This invariant property make the characterization of average polymer quantities for postgel easier.
    Synthesis of Amphiphilic Phosphate Carbonate-Copolymers and Drug Release Property of Their Microspheres
    KE Tian-Yi, ZHUO Ren-Xi
    1998, 19(8):  1335-1338. 
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    Four amphiphilic phosphate carbonate copolymers were synthesized by polycondensation of bisphenol A, phosgene and 2-bromoethyl phosphorodichloridate, and then quaternized with trimethylamine. The copolymers obtained were characterized by IR, 1HNMR and elemental analysis. Average molecular weight(Mn) and water contact angle were measured. The in vitro degradation of copolymers was studied in pH7.4 phosphate buffer solution at 37 ℃. Microspheres of these coploymer were prepared, their morphology, size and in vitro drug release of 5-Fu were also investigated.
    Characterization of the Phase separation in PMMA/α-MSAN Blends Using the Dynamic Viscoelastic Functions
    ZHENG Qiang, ARAKI Osamu, MASUDA Toshiro
    1998, 19(8):  1339-1342. 
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    The dynamic viscoelasticity of poly(methyl methacrylate)/poly(α-methylstyrene-co-acrylonitrile)(PMMA/α-MSAN) blends in the molten state was measured. By examining the correlation between dynamic storage modulus(G ′) and dynamic lose modulus (G ″), it was found that for the two components, the plots of lgG ′vs. lgG ″show no discernible or a little temperature dependence, and the slopes of the plots in the terminal region approach 2. But for PMMA/ α-MSAN blends, the slopes are less than2, exhibiting temperature dependence relevant to compositions of the blends. By comparing the lgG ′ vs. lgG ″ correlation between the two components and the blends, we obtained so called "critical temperatures(Tb)", which are useful for characterizing the phase separation of PMMA/ α-MSAN blends.
    Synthesis and Characterization of a New Chitosan Derivatives with Liquid Crystalline Behavior--O-Cynaoethylchitosan
    DONG Yan-Ming, LI Zhi-Qiang
    1998, 19(8):  1343-1345. 
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    O-cyanoethylchitosan was prepared at room temperature using sodium hydroxide as catalyst. Solubility of O-cyanoethylchitosan was prior to chitosan. While it dissolved, O-cyanoethylchitosan formed typical cholesteric liquid crystalline texture--fingerprint texture. The fingerprint texture can be frozen in films casted from 5% aqueous acetic acid solution. The droplet texture of positive birefriengence can also be observed in these films. Critical concentrations of cyanoethylchitosan in four acidic solvents were determined using polarized microscopy. All critical concentration values were in the range of 19%~20%(volume fraction), independing of the acidity of solvents.
    Preparation and Stability of Glucoamylase Immobilized on Porous Starch Graft Copolymer Beads
    WU Yong-Ge, GE Yu-Bin, SUN Wen-Tian, WANG Shu-Yan, ZHOU Hui, LI Wei
    1998, 19(8):  1346-1348. 
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    Glucoamylase from Aspergillus niger(EC3.2.1.3) was immobilized on porous starch graft copolymer beads (PSGC) which were synthesized in our laboratory. Some of the factors which influence the activity of the immobilized enzyme and the stability of the immobilized enzyme were investigated. The activity and special activity is 1340 IUper gram dry gel and 58.1 IUper millgram protein respectively when GA was immobilized under best condition found by ourselves. The optimium pHof the immobilized glucoamylase shifted 1.2 unit towards basic direction as compared to that of soluble enzyme. The thermostability of immobilized glucoamylase is longer than that of soluble enzyme, the operational half life of immobilized glucoamylase was 28 d and 8d with 20% dextrin as substrate at 55 ℃ and 60 ℃, respectively.
    Preparation and Photoconductivity of C60-containing Polystyrene Microspheres
    HU Jian-Hua, WANG Chang-Chun, YANG Wu-Li, MING Wei-Hua, FU Shou-Kuan
    1998, 19(8):  1349-1351. 
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    Polystyrene microspheres with diameter of 20μm were prepared by dispersion polymerization through two step swelling method. C60was successfully introduced to the surface of polystyrene microspheres through chloromethylation, azidation and cycloaddition. The C60-containing PSmicrospheres have photoconductivity, which orginates from the existence of C60.
    Synthesis and Characterization of Hybrid Inorganic/Organic Interpenetrating Polymer Networks
    WANG Jing-Yuan, QIN Dong-Qi, XI Chun-Yu, YU Xiao-Qiang, LI Yu-Wei
    1998, 19(8):  1352-1354. 
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    A hybrid inorganic/organic interpenetrating polymer networks of a three-dimensional network structure zeolite 13X and crosslinked or linear polybutylmethacrylate was prepared in this paper. By changing the content of crosslinker and the composition ratio, the size of zeolite channels and the crosslinking density were controlled. The results of DSC, SEM, TBAand mechanical properties show that zeolite 13Xis an inorganic skeleton and some organic PBMArun through it, which makes the whole inorganic/organic IPNmaterial not only have the rigidity of inorganic substance but also have the toughness of organic substance. At the same time it improves the thermal stability of organic material.
    Synthesis and Characterization of Poly(p-diethynylbenzene)
    LEI Zi-Qiang, YANG Mu-Jie, ZHAN Xiao-Wei
    1998, 19(8):  1355-1357. 
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    p-Diethynylbenzene was polymerized in the presence of cobalt-phosphine in diethylamine at room temperature with the yield of ca. 73.0% and the poly(p-diethynylbenzene) was obtained with the molecular weight of 11000. The polymers, being highly soluble in common organic solvents, possess the structure containing π conjugated linear polyenes as the main chain as well as p-ethynylbenzene component as pendant groups and emit intense fluorescence at 451.8 nm excited at UVlight in a toluene solution at room temperature.