Table of Content

24 November 2001, Volume 22 Issue 11

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Articles

Bilayer Electroluminescent Devices of Langmuir-Blodgett Films of Amphiphilic Complex Derivated from 8-Hydroxyquinoline Lanthanum

OUYANG Jian-Ming, LIN Wei-Han, HUANG Chun-Hui, ZHANG Li-Dong, LI Yong-Hang, YANG Chun-He

2001, 22(11):  1781-1784. 

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Organic electroluminescent (EL) devices with a bilayer structure (ITO/LBfilm/PBD/Al) were fabricated with an Langmuir Blodgett (LB) film of amphiphilic complex bis[ Nhexadecyl 8-hydroxy-2-quinoline carboxamide] lanthanum[La(HQ)₂Cl] as the emitting material. Excellent performance of the ELdevices originates from the insertion of an electron transport layer between the electrode and the emitting layer. Greenish yellow ELemission with a luminance of about 1219cd/m² was observed with a low voltage drive(7.5 V). The number of the layers of LBfilms and the deposited surface pressure have a strong influence on the I-Vcharacteristics, ELintensity, as well as break down voltage of the ELdevices. When the LBfilms were prepared at the surface pressure of 25 mN/m, the current density crossing this kind of diodes had stronger nonlinear I-Vcharacteristics and the organic ELdevice had a higher ELintensity than another device prepared at lower surface pressure(5 and 15 mN/m). At a lower surface pressure, there may be some point defects or pinholes in the LBfilm, in which the high tunnel current would increase exponentially with the field, leading to an increase in the current density crossing the ELdevice and a decrease in the recombination probability of electrons and holes at a higher voltage.

Solvothermal Syntheses and Crystal Structures of Chalcogenides SbSe₄ and In₃Te₇

CHEN Zhen, CHEN Ri-Yao, ZHENG Xi, LAN Rui-Fang, LIN Zhi-Hong

2001, 22(11):  1785-1789. 

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[Ni(en)₃][Hen]SbSe₄ (1)and [Sb(en)₃]In₃Te₇ (2) have been synthesized at180 ℃ by solvothermal technique by using ethylenediamine(en) as solvent for 7d. The crystal structures have been-determined by single crystal X-ray diffraction techniques. Compound 1 shows an isolated structure containing a Zintlanion, [SbSe₄]^3-, and a complex cation, [Ni(en)₃]²⁺, and a monoprotonated en cation [Hen]⁺. Compound belongs to the triclinic system, space group P1 with unit cell parameters: a=0.88143(18) nm, b=0.96235(19) nm, c=1.4278(3) nm, α=104.74(3)°, β=92.47(3)°, γ-=109.55(3)°, V=1. 0927(4) nm 3, Z=2. The structure of compound 2 consists of a Zintl anion, ²∞[In₃Te₇]^3- and a complex cation, [Sb(en)³]³⁺. Compound 2 belongs to the monoclinic system, space group P₂1/c, with unit cell parameters: a=1.0691(2) nm, b=1.6932(3) nm, c=1.5152(3) nm, α=90°, β=94.86(3)°, γ-=90°, V=2.7328 (9) nm³, Z=4.

Studies of Bound Form on Rare Earths in a Natural Plant Fern Dicranopteris Dichotoma by Spectroscopy

HONG Fa-Shui, WEI Zheng-Gui, ZHAO Gui-Wen

2001, 22(11):  1790-1794. 

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Distribution of REand structure characterization of REchlorophyll in a natural plant fern Dicranopteris Dichotoma in rare earth mining area were studied by spectrocopy. The results showed that the cerium content in total rare earths(79.43%, 66.71%) was the highest in leaf and chlorophyll, respectively. The fluorescence emission peaks of photosystem Ⅱ in D. Dichotoma were more violet shift by 15～25 nm than that of common plant. The fluorescence intensity of photosystem Ⅱ was as 6.79 time as that of photosystem Ⅰ. It showed that REScan increase the activities of photosystem Ⅱ. The spectral characterization of UV Vis and FTIRon chlorophyll a in D. dichotoma are similar as standard chlorophyll a and couldn't suggest coordination information on REs for its very low contents of REchlorophyll in D. Dichotoma. Extended X-ray absorption fine structure(EXAFS) spectral analysis revealed that cerium coordinated two porphyrin rings with coordination number of eight, the bond length of Ce-Nwas 0.252 nm, respectively; Ce-chlorophyll a may have bilayer structure in D. Dichotoma.

Studies on Phase Structures of N,N-Dimethyl-n-dodecyl Amine/Inorganic Oxyacid System

YIN Zhi-Lei, YANG Yong-Hui, SHAO Hua, SONG Xin-Yu, SUN Si-Xiu, YANG Tian-Lin

2001, 22(11):  1795-1799. 

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The phase structures of N,Ndimethyl n-dodecyl amine/inorganic acid systems have been investigated by the methods of the pseudo ternary phase diagrams, conductance, polarizing microscope, UV Vis spectra and FTIRspectra. The results can be expressed as follows: (1) With the increase of water phase content, the amine salt aggregated orderly in-different forms such as W/Omicro emulsion, nodus knot catenulate aggregates, layer liquid crystal and O/Wmicro emulsion. (2) In layer liquid crystal, SO₄^2- mainly combined with amine salt cation by two oxygen atoms in bridge. (3) In UV Vis spectrum of layer L.C., there is an absorption about 500 nm and light short circuit" appeared at about 430 nm. These phenomena may be very important for measuring the distance between the layers of the L.C..

Synthesis and Structure of a Tetracapped Keggin Polyarsenomolybdovanadate [Co(en)₂(H₂O)₂] ₂· [Mo₄^Ⅴ Mo₄^ⅥV₈^ⅣO₄₀ (AsO₄)] Containing Different Coordinated Cations

ZENG Qing-Xin, XU Ji-Qing, YANG Guo-Yu, LI Ya-Feng, CUI Xiao-Bing, ZHAO Xiao-Li, LI Chuan-Bi

2001, 22(11):  1800-1802. 

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The title compound [Co(en)₂(H₂O)₂] 2· [Mo^4Ⅴ Mo^4Ⅵ V^8Ⅳ O₄₀ (AsO₄)] was synthesized by hydrothermal method and its structure was determined with single crystal X-ray analysis. The cluster anion is a tetracapped Keggin polyanion, which contains different coordinated cations. The crystal is monoclinic, space group C2/c with a=1.4583(2) nm, b=2.17407(13) nm, c=1.8932(2) nm, β=91.532°, V=6.0002(10) nm³, Z=2, D_c=1.452 g/cm³, R=0.0359, Rw=0.0798, S=1.092.

Sodium Ion Transfer Across Micro Water/1,2-DCE Interface Facilitated by Liquid Crystal Crown Ether

TONG Yue-Hong, HUANG Zai-Fu, SHAO Yuan-Hua, WANG Er-Kang

2001, 22(11):  1803-1806. 

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The sodium ion transfer across the micro water/1,2-dichloroethane interface facilitated by a novel ionophore, liquid crystal crown ether was studied systematically. The sodium ion transfer facilitated by LCCEis controlled by diffusion studied by cyclic voltammetry. The diffusion coefficient of LCC-Ein-1,2-dichloroethane was calculated to be equal to (2.61±0.12)×10^-6 cm²/s and the stability constant of the complex between Na⁺ and LCCEwas determined as lg β_o=5.7 in 1,2-dichloroethane.

Studies on Anticoagulation Factor Ⅱ from Agkistrodon Acutus Venom by Rare Earth Ion Fluorescence Probes

XU Xiao-Long, LIU Qing-Liang, XIE Yong-Shu

2001, 22(11):  1807-1812. 

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The anticoagulation factor Ⅱ (ACF-Ⅱ) from Agkistrodon acutus venom has two Ca ²⁺ binding sites and Ca ²⁺ ions enhance the intrinsic fluorescence of ACF-Ⅱ. Rare earth ions (Nd ³⁺, Sm³⁺, Eu ³⁺, Gd ³⁺, Tb ³⁺ ) can replace the Ca ²⁺ ions in ACF-Ⅱ and have significant quenching effects on the fluorescence of ACF-Ⅱ. The characteristic fluorescence of Tb ³⁺ is enhanced through the nonradiative energy transfer from Trp residues in ACF-Ⅱ to bound Tb ³⁺. The fluorescence titration of ACF-Ⅱ with rare earth ions demonstrates that ACF-Ⅱ has two RE ³⁺ binding sites, and the rare earth ions and Ca ²⁺ ions bind to ACF-Ⅱ competitively in the same two sites. Although the ionic radii of Nd ³⁺, Sm ³⁺, Eu ³⁺, Gd ³⁺ and Tb ³⁺ are different, their apparent association constant K₁ or K₂ are similar, respectively. Linear free energy relationships for Tb ³⁺ and RE ³⁺ (RE=Nd, Sm, Eu, Gd) indicate that there is not an obvious size restriction for the binding of lanthanide ions at the two binding sites of ACF-Ⅱ, which reveals the conformational flexibility of the two binding sites in ACF-Ⅱ. This conformational flexibility offers a possibility for Ca ²⁺ ions, when they take place in the inducing conformational changes of ACF-Ⅱ and the binding of ACF-Ⅱ with the activated coagulation factor Ⅹ.

Preface

A Type of Fuzzy Classification Neural Networks for Complex Nonlinear Chemical Pattern Recognition

CHENG Yi-Yu, ZHAO Ming-Jie

2001, 22(11):  1813-1818. 

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For a type of classification problems of complex chemical patterns, in which the edges between pattern classes are rather irregular or ill defined, a new fuzzy computing method for chemical pattern classification is proposed. The new method was realized with a fuzzy neural network. An algorithm for training the fuzzy neural networks, which makes the fuzzy pattern classifier has the ability of learning from examples, is given. An example of classifying complex chemical pattern was used to verify the efficiency of the new method.

Articles

Investigation of Proton Transfer Across the Water/1,2-Dichloroethane Interface by o-Phenanthroline Using Glass Micro/Nano-pipets and Cyclic Voltammetry

YUAN Yi, SU Bin, SHAO Yuan-Hua

2001, 22(11):  1819-1823. 

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Facilitated proton transfer across the water/1,2 dichloroethane(DCE) interface supported on the tips of micro and nano pipets by o phenanthroline(Phen) was studied by using cyclic voltammetry. The formed micro and nano liquid/liquid interfaces functioned as micro and nano electrodes under certain experimental conditions. The dependence of the half wave potentials on the aqueous solutions acidities was studied and the ratio of association constants between Phen and proton in the aqueous and DCEphases was calculated by the method proposed by Matsuda et al.. The standard rate constant(k₀) and the transfer coefficient(α) evaluated by using nano pipets were equal to 0183±0054 cm/s and 070±009, respectively.

Isolation, Identification and Physiological Activities of₂-(1',2',3',4'-Tetrahydroxybutyl)-6-(2",3",4"-trihydroxybutyl)- pyrazine from Panax Notoginseng

LI Qi, YE Yun-Hua, YAN Ai-Xin, ZHOU Ya-Wei, SHEN Hong, XING Qi-Yi

2001, 22(11):  1824-1828. 

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Awater soluble polyhydroxy derivative of1,4 diazine has been isolated from panax notoginseng for the first time Its structure was determined as 2 (1',2',3',4'-tetrahydroxybutyl)₆ (2',3',4'-trihydroxybutyl) pyrazine by MS, NMR,¹H₁H COSY,¹H₁₃ C-COSY, HMBCetc, it was also confirmed by the synthesized sample Its activity of anticancer was studied.

Asymmetric Synthesis and Crystal Structure of β-Lactam Derivatives of₁,5-Benzothiazepines

LI Yuan, ZHANG Ping, LI Xu, ZHANG Li-Jun

2001, 22(11):  1829-1832. 

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Five optially active β-lactam derivatives of1,5 benzothiazepine have been synthesized by the reaction of 1,5 benzothiazepines with Nprotected glycine chloride using chiral oxazolidone as the chiral auxiliary and characterized by elementary analysis, IR,¹H NMR, MSand [α]_D²⁰. The crystal structure of compound Ⅱb was determined by single crystal X-ray diffraction. Crystal data: Mr=553.05, monoclinic with P2₁2_{121 space group, a=1.2293(2) nm, b=2.6026(5) nm, c=1.0146(2) nm, β=90°, V=3.2461(10) nm³, F (000)=1344, Z=4, Dc=1.312 g/cm³, R=0.0584, wR=0.1140. The structure analysis reveals that the conformation of sever-membered ring is chair-like, the substituents at C8 and C9 in β-lactam ring are located on the same side.}

Synthesis of 1,3-Bis(aryloxy acetyl)-1,3,2-diazaphospholidine-2-sulfide(selenide) Derivatives and Study of Their Herbicidal Activity

DENG Sheng-Lou, CHEN Ru-Yu, YANG Xiu-Feng

2001, 22(11):  1833-1837. 

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Aseries of new five membered phosphorus heterocycles were synthesized by cyclizing reaction of P(NEt-2)₃ with substrates containing diamino groups.The products were characterized by elemental analysis and spectrascopy. The preliminary bioassays showed that some compounds possessed a good selective herbicidal activity. In addition for the first time, the rearrangement of P⁼Se to P-Se in such phosphorus heterocycle was found, and the structure of the product together with intermolecular hydrogen bonds was confirmed by X-ray diffraction.

Investigation of Retention and Chiral Recognition Mechanism of the Derivative β-Cyclodextrin Bonded Stationary Phase(Ⅱ)

HUANG Jun-Min, CHEN Hui, GAO Ru-Yu, WANG Qin-Sun

2001, 22(11):  1837-1842. 

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The phenyl carbamate derivative β-cyclodextrin bonded phase CSP₁ and CSP₂ were prepared by the reaction of phenyl isocyanate. In normal phase condition, the enantiomers of a series of α-aminophosphonates have been separated on CSP₁ and CSP₂ by HPLC. In order to compare the different chromatographic property between the two CSPs, four molecular describing parameters reflecting the properties of the solutes were chosen to correlate against the experimental logarithim value of the capacity factor to form the quantitative structure enantioselective retention relationships(QSERRs) by the multivariable regression analysis and the factor analysis method. Through the QSERRs, the retention and enantioselectivity mechanism were examined.

Studies on Adsorption of TNF-α with Macroporous Resin

WEI Jiao, YU Yao-Ting

2001, 22(11):  1843-1845. 

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There are increasing evidences that high serum levels of Tumor Necrosis Factor(TNF-α) have been shown to be associated with disease severity in fulminant hepatic failure and dyscrasia, which is a principal mediator in the cascade of pathophysioligic events following endotoxic shock. In the present study, NK₁₁₀, carbonized resin and MET1004 are selected as adsorbents in the static adsorption experiments of TNF-α. We have investigated the adsorption capacity, kinetic profiles and adsorption isotherm of the three macroporous resins. Experimental results show that_mET1004 and NK₁₁₀ have higher adsorption capacities than carbonized resin. Compared with NK₁₁₀, the velocity of adsorption of MET1004 towards TNF-α is much faster than the former. From experimental data the adsorption rate constants k are calculated to be 0.0163 min^-1 (NK₁₁₀); 0.0189 min^-1 (carbonized resin); 0.0079 min^-1 (MET1004) at 37 ℃, respectively. Furthermore, their adsorption isotherms are also in-different shapes. They are shown to be'H"(MET1004);'L"(NK₁₁₀);'S"(carbonized resin) at 37 ℃, respectively. This demonstrated that the surface to volume ratio and the pore size of macroporous resins had an strong impact on the adsorption capacity and as the pore size increased, the adsorptive rate increased.

Studies on the Synthesis of Squaric Acid Ephedrine and Their Application in Asymmetric Catalytic Borane Reduction of Prochiral Ketones

L� Shou-Mao, ZHOU Hai-Bing, ZHANG Ji, XIE Ru-Gang, ZHOU Zhong-Yuan, CHAN Albert-S.C., YANG Deng-Kuei

2001, 22(11):  1846-1851. 

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Seven squaric acid ester amides or squaric acid diamides have been conveniently prepared by the reaction of natural ephedrine and squaric acid diesters, in which the later can be sythesized by refluxing squaric acid in the corresponding alcohols. When squaric acid amide ester 4a reacted with alkyl amines or was treated with aqueous sodium hydrosulfide, the new ligands which contain nitrogen or sulfur atom at C₃ of squaric acid were obtained. Five ligands were synthesized for the first time. The chiral oxazaborolidines formed in situ have been used in the enantioselective borane reduction of prochiral ketones and diketones to afford the alcohols in the range 85%-98% yields and 52.5%-87.4% enantiomeric excess respectively. All new ligand structures were comfirmed by IR,¹H NMR, MSand elemental analysis, the crystal structure of compound 4b was lerrified by X-ray diffraction.

Time-parameter Method(Ⅵ) Studies on Thermokinetics for Consecutive First-order Reactions

CHEN Yong, WANG Hai-Dong, LI Yan-Tuan, ZENG Xian-Cheng

2001, 22(11):  1852-1855. 

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According to the theoretical basis of thermokinetics, the integral and differential thermokinetic equations of consecutive first order reaction have been-deduced, and the mathematical models of the time parameter method for consecutive first order reaction have been established in this paper. Only needing the characteristic time parameter t_m, 2 t_m and 3 t_m and the corresponding thermoanalytical data from the same curve, the rate constants of the two steps can be determined simultaneously. Additionally, a novel method to determine the values of d Δ /dt by using the time parameter t_m, the peak height Δ m at time t_m and the total area of the curve, rather than by the use of slop from thermoanalytical curve at time t-with differential method, is proposed. The thermokinetics of saponifications of diethyl phthalate and diethyl adipate in aqueous ethanol solvent has been studied and the validation of the theory and method of the time parameter method for consecutive first order reactions is verified by the experimental results.

Studies on the Luminescence Properties and Decay Dynamics of Eu(Ⅲ) Enhanced Fluorescence Systems in Micelle Solutions

SUN Zhao-Yong, AI Xi-Cheng, FENG Juan, ZHANG Qi-Yuan, ZHANG Xing-Kang

2001, 22(11):  1856-1859. 

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The influence factors of luminescent properties of Eu ³⁺ in-different aqueous systems and the fluorescence enhancement_mechanism of Gd ³⁺ for Eu ³⁺ were studied by absorption and stable and transient fluorescence methods. The results of the fluorescence decay dynamics show that the first ligand(TTA), the second ligand(Phen), Gd ³⁺ and TX-100 can increase all the luminescence of Eu ³⁺. The lifetimes of 5-D-0 level of Eu ³⁺ in four systems are 980, 670, 400 and 260 μs, separately. Moreover, 5-D-1 level of Eu ³⁺ can transfer energy to 5-D-0 level.

Enhancement of IR Absorption of CO Adsorbed on Palladium-loading Zeolite Thin Film Electrode

JIANG Yan-Xia, SUN Shi-Gang, CHEN Sheng-Pei, DING Nan

2001, 22(11):  1860-1863. 

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In the present paper, clusters or nanoparticles of palladium were synthesized by using ship in a bottle technology in supercages of Yzeolite. In situ electrochemical FTIRreflection spectroscopy was employed to study COadsorption on nanoparticles of Pd in supercages of Yzeolte. Anovel phenomenon of enhancement of IRabsorption of adsorbed COwas revealed for the first time. In comparison with IRabsorption of COadsorbed on a massive palladium electrode, IRabsorption of COadsorbed on nanoparticles of Pd has been enhanced up to about 40 times. The results also demonstrated that the new phenomenon of enhancement of IR-absorption is related to the nanometer scale of Pd clusters and also to the particular environment of supercages of Yzeolite.

Comparative Molecular Field Analysis of γ--Hydroxy Butenolide Endothelin Antagonists

GU Chang-Ming, HOU Ting-Jun, XU Xiao-Jie

2001, 22(11):  1864-1868. 

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Three dimensional structure activity relationships of γ- hydroxy butenolide endothelin antagonists were studied using CoMFAtechnique. Besides the steric and the electrostatic fields, the Hbond field was introduced into the computations. The QSARresults showed that the introduction of the Hbond field improved the quality of the obtained CoMFAmodel obviously. The model can forecast not only the compounds in the training set but also the compounds in the test set. The CoMFAcontour plots identified several key features including steric, electrostatic and Hbond fields, which were valuable for us to get insight into the potential mechanisms of the intermolecular interactions between inhibitor and receptor. Suitable steric and electrostatic effects as well as Hbond donor and acceptor are required for a higher activity.

Nonlinearity Enhancement by Proton Transfer: A New Strategy for the Design of Nonlinear Optical Materials

FU Wei, FENG Ji-Kang, PAN Ge-Bo

2001, 22(11):  1869-1872. 

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The theoretical considerations of the molecular hyperpolarizabilities of donor acceptor substituted aromatic molecules show that the transfer of a proton from the electron-donor group of an acid HO-C₆H₄-CHCH-C₆H₄-NO₂(OSN) to the electron acceptor group of a base Me 2N-C₆H₄-CHCH-C₅H₄N(DAMS) could significantly increase β and γ for both resulting ionic species relative to the corresponding neutral molecules by using ZINDO SOS, FF/PM3 and CPHF/PM3 three methods.

Effect of Precipitant on the Performances and Structures of Au/ZnO Catalysts for CO Oxidation

WANG Gui-Ying, LIAN Hong-Lei, XU Yue, ZHANG Wen-Xiang, JIANG Da-Zhen, WU Tong-Hao

2001, 22(11):  1873-1876. 

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Various Au/ZnOcatalysts were prepared by a coprecipitation method with four kinds of precipitants, Na₂CO₃, (NH₄)₂CO₃, NaOHand NH₄OH, and the catalytic performance of COoxidation at an ambient temperature and humidity were studied. It was found that the precipitants play an important role for the Au/ZnOcatalyst structure, such as the precursors, the particle size of ZnOand metallic gold and the BETsurface area of Au/Zn Ocatalysts. The sample prepared by using NH₄OHas precipitant exhibited a lower activity and poorer stability, while the Au/ZnOcatalysts prepared by other three precipitants can maintain COcompletely oxidized to CO₂ for at least1100 h. The feed gas mixture can result in sintering of metallic gold and accumulation of carbonate like species on the surface of Au/ZnOcatalysts during the CO-oxidation process. The stability is related to the rate of gold sintering and the amount of hydrozincite formed on the catalyst surface.

Preparation of Solid Acid SO₄^2-/Fe₂O₃-SiO₂ by Stearic Acid Method and Preliminary Study on Its Catalytic Activity

WU Dong-Hui, LI Dan, YANG Juan, YANG Xu-Jie, LU Lu-De, WANG Xin

2001, 22(11):  1877-1880. 

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Fe₂O₃ SiO₂ mixed oxides were prepared by stearic acid method for the first time. After being impregnated by H₂SO₄ solution and calcined at a certain temperature, the mixed oxides formed a solid acid. The samples were characterized by XRD,TEM, N₂ adsorption/desorption and TG-DTAmethods. The results showed that with the increasing of SiO₂ content the specific surface areas of Fe₂O₃ SiO₂ mixed oxides increased significantly, but the porous sizes decreased. The catalytic activities of the solid acid catalysts were evaluated by esterification of acetic acid and butanol.

Converting Octadecanol to Unsaturated Fatty Acids Catalyzed by Mortierella Isbellina

XIAN Mo, YAN Ji-Chang, ZHEN Ming, ZHOU Guang-Dong, LI Wen-Xing, BI Ying-Li, ZHEN Kai-Ji

2001, 22(11):  1881-1884. 

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Mortierella isabellina was found to be used to synthesize unsaturated fatty acids when the fungus was cultivated in a medium consisting of 2% octadecanol,1% yeast extract and Mg ²⁺ with concentration at 25 mmol/Lat 23 ℃ for120 h. The harvested dry cells contained 47.5% lipids, 28.9% carbohydrate and 31.5% protein. The results showed that the lipid selectivity was 30.6%, at a yield of 20.6%. The data also indicated the selectivity of fatty acids in the lipids, was palmatioleic(0.81%), oleic(20.75%), linoleic(1.95%), linolenic(2.19%) respectively. Lowering the concentration of substrates in the medium led to increasing selectivities of both lipids and unsaturated fatty acids synthesized by the fungus, and when mass fraction of octadecanol was 0.5%, the maximal selectivities of the corresponding fatty acid were obtained. Astudy of initial pHof the medium suggested that the maximal selectivity and yield of lipids were obtained at a pHvalue of 7. The octadecanol conversion reached a maximum(88%) when cultivated at 33 ℃, however, the lipid yield reached a maximum(9.7%) at 23 ℃. Mg ²⁺ was found to strongly influence the productivity of lipids and unsaturated fatty acids. For instance, a concentration of 25 mmol/Lof Mg ²⁺ in the culture broth may cause a maximal selectivity(25.7%) and yield(17.6%) of lipids.

Electronic Paramagnetic Resonance Characteristics of ZnO Ultrafine Particles and Their Photocatalytic Performance

JING Li-Qiang, ZHENG Ying-Guang, XU Zi-Li, DONG Feng-Xia, SUN Xiao-Jun, CAI Wei-Min, XU Ying-Kai

2001, 22(11):  1885-1888. 

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EPRproperties of ZnOultrafine particles(UFP) and their photocatalytic activities were studied by using XRD, TEM, XPSand EPR. Results show that UFPobtained by calcining the precursor, zinc carbonate hydroxide at 320, 430, 550 and 700 ℃, have sizes of 13.5,19.3, 26.1 and 38.5 nm, respectively, with wurtzite structure attached to the hexagonal system. Results also show that at room temperature ZnO UFPhad a significant EPRsignal with single line resulting from the O₂-deficiencies on the surface of ZnO UFPwhich can capture and trap electrons so as to form a spin resources with S=1/2. Their EPRintensity decreased with the increase of their sizes. But at the liquid nitrogen temperature, the EPRhad six hyperfine structures resulting from the hyperfine interaction between the electrons traped by O₂-deficiencies and the17 Omagnetic nucleus with I=5/2 attached to the absorbed oxygen on the surface of ZnO UFP. The photocatalytic activities of ZnO UFPdecreased as their EPRintensity decreased during the process of photocatalytic oxidation SO₂ and C₇H₁₆, suggesting that oxygen-deficiencies on the surface of ZnO UFPplayed an important role in photocatalysis.

Electronic Structure of Carbon Nanotube in the Growth

ZHOU Gang, DUAN Wen-Hui, GU Bing-Lin

2001, 22(11):  1889-1892. 

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The electronic structure of single walled carbon nanotube (SWNT) in the growth is studied by using the first principle discrete variable calculations. We find the electronic structure of the mouth is remarkably different from that of the body due to dangling bonds. The corresponding valence electrons not only directly change the bonding model of the mouth, strengthen the bonding between carbon atoms and induce carbon atoms shift to tube core along the radial, which is in good agreement with the morphology of perfect tip observed in the experiments, but also reduce the chemical stability of carbon nanotube. The electronic structure differing from the closed carbon nanotube determines the different operation behavior of carbon nanotube in the growth in the synthesis of nano material.

Theoretical Study on the Potential Felt by a Single Electron within a Molecule

ZHAO Dong-Xia, GONG Li-Dong, YANG Zhong-Zhi

2001, 22(11):  1893-1895. 

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The potential felt by a single electron within a molecule represents the total interaction energy of this electron with all nuclei and the rest electrons in the molecule and is an important quantity. It is formulated and then calculated by using the ab initio MELDprogram plus a separate calculation program. We have systematically investigated and discussed this kind of potentials for a series of molecules. In terms of the three dimensional graph, the variation of the potential acting on the single electron within a molecule has clearly and visually been shown, and hence the electronic movement and the chemical bonding can be deeply understood.

Configuration Interaction in Valence Bond Theory

SONG Ling-Chun, WU Wei, CAO Ze-Xing, ZHANG Qian-Er

2001, 22(11):  1896-1897. 

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Configuration interaction tenichque is applied to the valence bond theory. Virtual VBorbitals are built, which are localized and orthogonal to their corresponding occupied orbitals and the excited VBstructures are defined, which come from their corresponding fundamental VBstructures. The testing calculations of H₂, LiH, HFshow that the VBresults using CImethod match those of the molecular orbital based on the coupled cluster CCSDmethod, and the CItechnique may become a useful tool in VBmethod.

Synthesis and Characterization of a Novel Layered Zeolite MCM-56

XU Ning, WU Tong-Hao, WANG Dong-Yang, WU Peng, KAN Qiu-Bin, SUN Jia-Zhong

2001, 22(11):  1898-1900. 

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MCM-56, a novel layered zeolite, has been synthesized under a stirring condition by hydrothermal method and characterized by XRD, TEM, TGand DTA. TEMshows that most of the crystals exist in the form of single layer. Based on the experimental facts and framework type which MCM-56 belongs to, MCM-56 should consist of very thin MWWtype layers which are just one unit cell along the c direction, and have a unique architecture with two dimensional10 MRpore system inside the layer and 12-MRcups(half of the MWWcages described in the MCm-22 or MCM-49) on the crystal exterior without cages between layers.

In situ Measurement of pH Value on the Cathode/Solution Interface

ZHANG Jian-Min, YANG Chang-Chun, SHI Qiu-Zhi, WU Qiang, CHENG Peng-Li

2001, 22(11):  1901-1903. 

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In this paper, a pHmicroprobe technique was developed to measure in situ the pHvalue on the cathode/solution interface, and iridium oxide was used as a pHsensitive material which is of a good response behavior in the measured solutions. During electrodeposition process of bioceramic coatings of calcium phosphates, the interfacial pHchange, for example, was first_measured. The experimental results indicated that the pHvalue on the cathode/solution interface first jumped to a maximum, then slowly decreased with the increase of the electrodeposition time. The interfacial pHvalue was increased with the applied current density or cathode overpotential.

Nuclear Magnetic Resonance Studies on the Effects of Rare Earth in Rats Urine

LI Xiao-Jing, FENG Jiang-Hua, PEI Feng-Kui, CHEN Xi, LI Shu-Lei, NIE Yu-Xiu

2001, 22(11):  1904-1906. 

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Male Wistar rats were administrated orally with La(NO₃)₃ at doses of 0.05, 0.2, 2.0,10 and 20 mg/kg body weight. Urine was collected over a 24 h period after dosing. Resonances for a large number of low molecular weightmetabolites were assigned in a high resolution₁H NMRspectra of rat urine. The variation of some low molecular weightmetabolites in urine provided a sensitive measurement of Rare Earth induced renal and liver lesions, in which DMA, DMG, urea, Kg, TMAO, succinate, citrate and amino acids have been suggested as NMRmarkers for renal damage and ethanol, lactate, taurine as the markers for liver damage. The method could be applicable to study of the toxicological effects of other compounds and drugs.

Styrene Epoxidation with t-Butyl Hydroperoxide Catalyzed by Nanometer TiO₂(Ⅱ)

QI Jian-Ying, YANG Qi-Yun, LIU Zhen-Yi, KAN Jia-De, YUAN Bo, MO Wei

2001, 22(11):  1907-1909. 

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The catalysts of nanometer TiO₂/BuOHand hydrous TiO₂ were prepared by the liquid phase method from Ti(SO₄)₂. The properties of the catalysts were characterized by TG-DTA, IR, XRD, TEMmethods. The results showed that nanometer TiO₂/BuOHwas anatase particles with10 nm×20 nm. The main product in styrene epoxidation with t butyl hydroperoxide(TBPH) was styrene epoxide, by product was phenylformaldehyde under the condition of 80 ℃ for 6 h. Hydrous TiO₂ prepared below 260 ℃ was non crystal powder and converted into anatase particles with10 nm×300 nm when it was roasted at 500 ℃. The catalytic activity of10 nm×300 nm anatase particles had only 50% that of particles with10 nm×20 nm. The centers of acid on the catalyst surface made the epoxide selectivity decrease obviously. The order of the influence of solvent on epoxidation reaction:1,2 dichloroethane>butanol>cyclohexanone>methyl cyclohexane>cyclohexanol>acetic acid.

Effect of Sn-doping on Photocatalytic Activity of TiO₂ Film for Degradation of Phenol

CAO Ya-An, SHEN Dong-Fang, ZHANG Xin-Tong, MENG Qing-Ju, MA Ying, WU Zhi-Yun, BAI Yu-Bai, LI Tie-Jin, YAO Jian-Nian

2001, 22(11):  1910-1912. 

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We prepared TiO₂(anatase) and Sn-doped TiO₂ nanoparticlate film by Plasma enhanced Chemical Vapor Deposition(PECVD) method. XR-Dand XP-Sexperiments showed that Sn was doped into the lattice of TiO₂ with a ratio of n-(Sn): n-(Ti)=1:10. Sn-doping largely enhanced the photocatalytic activity of TiO₂ film for phenol degradation. The enhancement in photoactivity by doping was discussed, based on the characterization with AFM, FTIRand EFISPS. Sn-doping produced localized level of Sn ⁴⁺ in the band gap of TiO₂, about 0.4 eVbelow the conduction band, which could capture photogenerated electrons and reduce O₂ adsorbed on the surface of TiO₂ film, thus accelerated the photocatalytic reaction.

Direct Synthesis of Isocyanates by Electrocatalytical Carbonylation of Amines at Atmospheric Pressure

YANG Hong-Zhou, DENG You-Quan, SHI Feng, SIMA Tian-Long

2001, 22(11):  1913-1915. 

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Anovel synthesis of several isocyanates by direct electrocatalytical carbonylation of corresponding amines can proceed through an electrochemically regenerable palladium(Ⅱ) catalyst in combination with copper acetate as cocatalyst with an excellent conversion and selectivity under mild conditions. The results show that Pd(PPh-3)₂Cl₂ was the best catalyst. For aromatic amines, the main products were the corresponding isocyanates. And for aliphatic amines, various products were detected.

Preparation and Characterization of Monolithic TiO₂ Aerogels

CHEN Long-Wu, GAN Li-Hua, XU Zi-Jie

2001, 22(11):  1916-1918. 

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Monolithic TiO₂ aerogels have been prepared from titanium n butoxide by sol-gel process and supercritical drying technique, and the structural properties of the aerogel samples have been characterized by means of SEM, TEM, XRD, IR, BETand pore distribution analysis. The results indicated that the optimum condition for preparing monolithic TiO₂ aerogels was n-[Ti(OC₄H₉)₄]: n-(C₂H₅OH): n-(H₂O): n-(HNO₃)=1:18.3:3.75:0.14. The final aerogels which consist of colloidal particles with diameters of about 5 nm were found to be with coherent uniform size and low density solid inorganic materials with porosity of about 90%, and contained mesopore in the range of 10-20 nm. The monolithic TiO₂ aerogels were of the pure amorphous form at room temperature, which would be converted into anatase and then into rutile by increasing the temperature of heat treatment.

Studies on Chain Extension Reaction of Poly( ε-caprolactone) Segmented Polyurethane with Different Soft-segment_molecular Weights

LU Yu-Chen, LUO Xiao-Lie, MA Jing-Wen, ZHANG Zhong-Ping, MA De-Zhu

2001, 22(11):  1919-1923. 

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Aseries of poly(ε-caprolactone) segmented polyurethane with different molecular weights (PCL) were synthesized. The kinetics of the chain extension reaction was studied by infrared (IR) spectroscopy. The kinetics parameters show the following characteristics of the chain extension reaction. The rate constants decrease with increase in the number average molecular weightmn of the soft segment at the same hard segment reactant content. The influences of M_n on the reaction rate vary with the variation of the hard segment reactant contents. All of the chain extension reactions studied in this work were of second order. The activation energies were essentially insensitive to the M_n, but they increased a little with increase of hard segment reactant content.

Preparation and Property Study of Novel Composite Epoxy-type Optical Resins

LV Chang-Li, CUI Zhan-Chen, ZHAO Dong-Xue, YANG Bai

2001, 22(11):  1924-1928. 

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Bis( β-epoxypropylthioethyl) sulfide(DGEMES) was synthesized from 2,2'-dimercaptoethyl sulfide(MES) and epichlorohydrin and it's structure was characterized by FTIRand MS. Ethylenediamine was used to cure the mixture of DGEMESand DGEBA, a novel optical resins with a high refractive index and low dispersion were obtained. The studies indicated that DGEMESis a good monomer for copolymerization. With increasing it's content, the refractive index and Abbe number of the copolymer can be increased at the same time. The cured resins of DGEMES/DGEBA/ethylenediamine have a higher refractive index 1.59-1.62 and a large Abbe's number 35-39; especially, when the content of DGEMESis 40% in weight, the cured copolymer has a high refractive index(nd>1.60) and a higher impact strength(22.5 kJ/m²), and other well balanced properties, which is also important for optical materials. In addition, B-650 was used as a curing agent, the cured resins of DGEMES/DGEBA/B-650 were prepared, which possess middle degree of refractive index. The n_d and ν_d values of the resins, ranging between 154-156 and 38-40, were measured by refractometer, the optical and mechanical properties of them were discussed in this paper.

The Preparation of Amphiphilic Colloidal Particles with Hydrophobic Core and Hydrophilic Shell

YUN Yang, LI Hang-Quan

2001, 22(11):  1929-1931. 

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Amphiphilic colloidal particles were prepared with hydrophobic polystyrene cores encapsulated by hydrophilic polyacrylamide shells. The polystyrene colloidal particles were prepared by using a concentrated emulsion as a precursor. The polyacrylamide shell is prepared via redox initiation. Anotable feature of the particles is that no copolymer jointing portions exist. The hydrophobic cores were just encapsulated by hydrophilic shells. The porous shell ensured the hydrophobic cores accessible to the outside media. As a result, such particles could be dispersed in both water and diesel oil. That is to say, they were compatible with both polar and nonpolar solvents. SEMphotographs confirmed the shell structure. The amphiphilicity of the particles was characterized by their water and diesel oil absorbabilities. It was found that polymerization recipes and reaction conditions, the amount of redox initiator, diluent, hydrophilic monomer, crosslinker and the temperature of polymerization, could adjust the structure and thickness of the hydrophilic shells. Such amphiphilic colloidal particles can be used widely in-drug delivery and catalytic processes.

Studies on Synthesis and Properties of Novel Polyarylether Containing Dimethyl-substituted Phthalazinone Moieties

JIAN Xi-Gao, ZHU Xiu-Ling, CHEN Lian-Zhou

2001, 22(11):  1932-1935. 

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Anovel bisphenol like compound, 4-(3,5-dimethyl-4-hydroxylphenyl)-2,3 phthalazine1 none (DM HPPZ) was used to successfully prepare a kind of thermal stable polyarylethers with 4,4'-diflourodiphenylketone(Ⅰ) and 4,4'-dichlorodiphenylsulphone(Ⅱ) via nucleophilic substitution. High molecular weight polymers with inherent viscosity more than 44.2-75 mL/g are acquired in 7-75 h. These polymers exhibit a higher glass transition temperature( T_g=568-595 K) than unsubstituted polymers( T_g=536-578 K) and good thermostability with 5% weight loss at the temperature above 689 Kin nitrogen. Also the copolymers(PPESK) with different ratios of Ⅰ to Ⅱ aimed at the combination of the excellent strength of PPEKand the high temperature resistance of PPESare obtained. The polymers have a tensile strength in the range of 454-850 MPa. They are readily soluble in polar aprotic solvents such as chloroform, N,Ndimethylacetamide etc, and are easily cast into flexible, transparent films from them.

Single-chain Microgels from Poly( N-isopropylacrylamide) Copolymer

ZHOU Nan, ZHOU Ru-Ling, YAN Xiao-Hu, WANG Zhi-Liu, CHENG Rong-Shi

2001, 22(11):  1936-1937. 

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The'single chain" microgels were synthesized successfully from the crosslinkable Poly( Nisopropylacrylamide) copolymers. The viscosity properties show that the microgels have an even higher LCST than that of the corresponding linear copolymers.

The Effect of Self-nucleation on Structure and Properties of iPP

WANG Song, YANG De-Cai

2001, 22(11):  1938-1939. 

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The effects of self seeding nucleation on the crystallization behavior and properties of polypropylene (iPP) were studied. DSCresults indicated that the crystallization temperature of iPPincreased obviously after the process of self seeding nucleation. The results of polarized light microscopy showed that the spherulite size decreased markedly, as a result, the mechanical properties and the transparency of iPPwere all improved.

A Comparative Study on Morphology of Block Copolymer Using Atomic Force Microscopy and Transmission Electronics Microscopy

WANG You, LI Ying-Shun, SONG Rui, SHEN Jing-Shu, LONG Cheng-Fen

2001, 22(11):  1940-1942. 

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The morphology of poly(styrene ethylene/butylene styrene)(SEBS) triblock copolymer cast from heptane and toluene was studied by combining atomic force microscopy(AFM) with transmission electronics microscopy(TEM). The quantitative agreement of the results of AFMand TEMplays a key role in-determining the phase attribution for the AFMimages. It is confirmed that under the moderate tapping condition, the hills in AFMheight images correspond to the polystyrene phase and the valleys to the rubbery phase.

Preface

Preparation of Photosensitive Polyimide/Titania Hybrid by Sol-gel Method

LIU Li, LU Qing-Hua, YIN Jie, ZHU Zi-Kang, WANG Zong-Guang

2001, 22(11):  1943-1944. 

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Photosensitive polyimide/titania hybrid was prepared successfully by sol gel process. This hybrid material posseses a good photolithographic property under UVexposure. The introduction of titania leads to the increase in refractive index of the hybrid.

Articles

Fabrication of Polystyrene Colloidal Crystals

HAO Ling-Yun, ZHOU Yong, JIANG Wan-Quan, ZHU Yu-Rui, LI Fan-Qing, HU Yuan, CHEN Zu-Yao

2001, 22(11):  1945-1947. 

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In this paper, we have successfully fabricated the colloidal crystals of monodispersed polystyrene latex. Styrene was polymerized in-degassed water at 75 ℃, using potassium persulfate as an initiator. The surfactant was sodium dodecyl sulfate(SDS). Firstly, the monodispersed polystyrene latex with an average diameter of some nanometers was synthesized via emulsion polymerization, then these small latex particles were used to act as seeds for further growth. The size of polystyrene latex was controlled between₅₀ nm and 400 nm via diversifying the condition of polymerization. The resulted emulsion solution could accumulate slowly to form three dimensional ordered structure, which was induced by capillary as the solvent evaporating at room temperature. The opal is close packed face center cubic(f.c.c) lattice of polystyrene latex. Defects such as vacancies, dislocations or grain boundaries could be obviously observed from the SEMimages. Reflectance spectra showed the red shift of specular reflectivity peak for the polystyrene colloidal crystal as the size of polystyrene latex increasing. It was demonstrated that the reflectance is intrinsic property of these colloidal crystals. This provides ideal model for the research and application of photonic crystals and form useful template for growth of various ordered macroporous materials.

UV Studies on Aluminoxane EBAO and Its Influence on Ethylene Polymerization

ZHAO Yan, WANG Qi, FENG Lin-Xian

2001, 22(11):  1948-1950. 

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Ethyl-(iso-butyl) aluminoxane(EBAO) was synthesized and characterized by UV Visible spectrum. The four absorption peaks of UV Visible spectrum of EBAOwere assigned to the different sequence distributions of alkyl groups of EBAO. Ethylene copolymerization by Et(Ind)₂ZrCl₂/EBAOand MAOwas investigated. The interaction between metallocene and aluminoxanes was monitored by UV-Visible spectra. It was found that EBAOwould form looser ion pair than MAOand accounted for the high comonomer incorporation of copolymers synthesized by EBAO.

Atom Transfer Radical Copolymerization of Unsaturated Cyclic Acetal with Styrene

YUAN Jin-Ying, XU Xu-Rong, PAN Cai-Yuan

2001, 22(11):  1951-1953. 

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This paper is the first report on the atom transfer radical copolymerization of unsaturated cyclic acetal, 4,7-dimethyl-2-methylene-1,3-dioxepane(DMMDO) and styrene(St) in the presence of α bromobutyrate as the initiator and CuBr/2,2'-bipyridine as the catalyst/ligand at 110 ℃ was investigated. Both DMMDO and St components could be found in main chains of the obtained polymer, and the copolymer had a narrow molecular weight distribution. DMMDO component in the copolymer contained both addition and ring opening units, thus the ester bond was introduced into the main chain, and the copolymer could be chemically degradable and biologically degradable.