Table of Content

10 February 2012, Volume 33 Issue 02

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Content

Cover and Content of Chemical Journal of Chinese Universities Vol.33 No.2(2012)

2012, 33(02):  0-0. 

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Article: Inorganic Chemistry

Synthesis, Structure and Properties of Novel Homochiral Metal-organic Coordination Polymers

CHEN Wan, SU Sheng-Qun, SONG Shu-Yan, SONG Xue-Zhi, ZHANG Hong-Jie

2012, 33(02):  215-218.  doi:10.3969/j.issn.0251-0790.2012.02.001

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Two new homochiral metal-organic coordination polymers[M(D-cam)(H₂mbdpz)]_n[M=Zn(complex 1), Co(complex 2); D-H₂cam=D-(+)-camphoric acid, H₂mbdpz=4,4'-methylenebis(3,5-dime-thylpyrazole)] were prepared by mixing ligands with corresponding transition metal ions under hydrothermal conditions. The complexes were characterized by means of single-crystal X-ray diffraction, elemental analysis, thermograrimetri analysis(TGA), powder X-ray diffraction(XRD) and photoluminescent(PL) spectrometry. X-ray crystallography reveals that complexes 1 and 2 are isomorphous and homochiral, exhibiting the three-dimensional open structure with a ThSi₂ type of uninodal 3-connected networks.



In vitro Evaluation of Antibacterial and Osteogenic Properties and Synthesis of Mesoporous Hydroxyapatite/Chitosan Composite Loaded with Vancomycin as a Drug Delivery

ZHANG Jing-Zhe, LI Dong-Dong, LIU Gui-Feng, WU Qiong, WANG Jin-Cheng

2012, 33(02):  219-224.  doi:10.3969/j.issn.0251-0790.2012.02.002

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Mesoporous hydroxyapatite/chitosan(HA/CS) composite loaded with vancomycin(VCM) was synthesized using a freeze-drying method, and characterized by SEM, XRD and FTIR. The results showed that mesoporous HA/CS presents higher surface area and porosity. The concentration of vancomycin released from mesoporous HA/CS, the efficacy of the mesoporous HA/CS against methicillin-resistant Staphylococcus aureus(MRSA), the effect of mesoporous HA/CS on early adhesion, proliferation and differentiation of osteoblast cells in vitro were measured. Antibacterial assays indicated that mesoporous HA/CS loaded with vancomycin had the effect on growth of organisms and keep the diameter of inhibition zone until it disappeared for 13 d. MTT cytotoxicity test and cell adhesion test show that the materials have good biocompatibility and make cell viability and proliferation. In vitro testing using osteoblast-like cells show that the surfaces of the cells are able to adhere, proliferate, and migrate through the pores. These cells maintained similar expression levels of osteoblastic-associated markers, namely collagen type Ⅰ(COL-1), alkaline phosphatase(ALP), bone morphogenetic protein-2(BMP-2). It can be concluded that the mesoporous HA/CS loaded with vancomycin possesses good antibacterial capability and osteogenic properties in vitro and represents a promising candidate for bone regeneration as a drug delivery.



Structure-tunable Synthesis and Structural Stabilities of the Multilayered Titanate Nanotube Thin Films Grown on Titanium Metal Surface

PAN Yan, GUO Yu-Peng, SONG Wen-Bo, LIU Zhi-Hui

2012, 33(02):  225-229.  doi:10.3969/j.issn.0251-0790.2012.02.003

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Multilayered titanate nanotube thin films were grown on titanium metal surface via a hydrothermal surface treatment process. A general formation mechanism for oriented titanate nanotube thin film was proposed on the basis of detailed SEM and TEM observation of the products. The overall formation of titanate nanotube can be summarized as a sequence of four steps: (1) titanium dissolution and alkali titanate hydrogel formation; (2) alkali titanate hydrogel dissolution and layered Na₂Ti₃O₇ formation; (3) layered Na₂Ti₃O₇ growth; (4) nanotube formation via Na₂Ti₃O₇ splitting and the multilayer scrolling process. The effects of post-treatment conditions on the film morphology and stability were examined. The layer-delaminating of multilayered titanate nanotube thin films were obtained after ultrasonic treatment.



Third-order Nonlinear Optical Properties of CuInS₂ Quantum Dots Doped Glass

XIANG Wei-Dong, ZHAO Hai-Jun, YANG Xin-Yu, ZHONG Jia-Song, LUO Hong-Yan, GUO Yu-Qing, LIANG Xiao-Juan, YANG Xin-Qi

2012, 33(02):  230-235.  doi:10.3969/j.issn.0251-0790.2012.02.004

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CuInS₂ nanocrystals doped sodium borosilicate glass were prepared by employing both sol-gel and atmosphere control methods. Morphology and microstructure of CuInS₂ nanocrystals in the glass were characte-rized by means of X-ray powder diffraction(XRD) and transmission electron microscope(TEM). Femtosecond Z-scan technique was employed to study the third-order nonlinear optical properties of the glass. The results show that CuInS₂ nanocrystals in tetragonal crystal system form uniformly in the glass, and the size of the nanocrystals is about 10 nm. The results of femtosecond Z-scan technique show that the glass exhibits excellent third-order nonlinear optical properties, and the third-order nonlinear optical refractive index γ, absorption coefficient β and susceptibility χ⁽³⁾ of the glass are determined to be 8.57×10^-16 m²/W, 3.74×10^-8 m/W, and 1.95×10^-17 m²/V², respectively.



Structure and Electrochemical Performance of LiFePO₄ Cathode with Coating Super Iron Conductor Li₃ V₂(PO₄)₃

ZHANG Xiao-Ping, GUO Hua-Jun, LI Xin-Hai, WANG Zhi-Xing, PENG Wen-Jie, WU Ling

2012, 33(02):  236-242.  doi:10.3969/j.issn.0251-0790.2012.02.005

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The composite 9LiFePO₄@Li₃ V₂ (PO₄)₃ was prepared by coating super ion conductor Li₃ V₂ (PO₄)₃ on the surface of LiFePO₄ particles through mechanical activation method. X-ray diffraction, scanning electron microscopy, high resolution transmission electron microscopy, energy disperse spectroscopy and electrochemical measurements were used to evaluate the properties of the cathodes. The coated LiFePO₄ contains olivine LiFePO₄, monoclinic Li₃V₂ (PO₄)₃ and orthorhombic Li₃ PO₄ phases . As LiFePO₄ particles are encapsulated with a layer of Li₃ V₂ (PO₄)₃ and some V³⁺ ions are incorporated into the olivine structure, the LiFePO₄ lattice parameters decrease. Subsequently, the exchange current density and lithium ion diffusion coefficients of coated LiFePO₄ are separately improved one order of magnitude. Electrochemical measurements indicate that the rate capability and cycle performance of coated LiFePO₄ are significantly enhanced. Compared with bare LiFePO₄, the first discharge capacity of coated LiFePO₄ is raised 34.09% and 78.97% at 1C and 2C rates, while the capacity retention increases 27.77% and 65.54% after 150 cycles, respectively. Furthermore, the 9LiFePO₄@Li₃ V₂ (PO₄)₃ exhibits initial discharge capacity of 121.379 mA·h/g at the rate of 5C and its capacity retention is 94.03% after 350 cycles, while the pure LiFePO₄ almost shows no capacity at the same rate.



Synthesis, Characterization and PTP1B Inhibitory Activity of the Vanadium Complexes with Amino-acids

ZHANG Heng-Qiang, ZHANG Qi-Ying, LI Jia, LIU Dong, WU Xiao-Fang, SHAN Yong-Kui

2012, 33(02):  243-250.  doi:10.3969/j.issn.0251-0790.2012.02.006

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Two vanadium-amino acid-hydroxylamido complexes,[VO(NH₂O)₂(C₅H₁₀O₂N] (1) and K[VO(NH₂O)₂(C₆H₁₂NO₂N]₂Cl·H₂O(2) were synthesized. Their structures and components were characterized by elemental analysis, IR spectrometry, UV-Vis spectrometry, thermal analysis and X-ray single crystal diffraction and their PTP1B inhibitory activities were also explored. Complexes 1 and 2 both crystallize in triclinic system with space group P1. The central vanadium and seven coordinated atoms form a distorted pentagonal bipyramidal. Two O atoms and three N atoms from hydroxylamine and amino-acids define an equatorial plane approximately perpendicular to V＝O. The N of hydroxylamine is cis to N of amino-acids and the O of amino-acids is trans to V＝O. Complex 2 displays a good inhibitory activity against PTP1B(inhibition rate is 90.51% at 20 μg/mL).



Analytical Chemistry

Surface Plasmon Resonance Imaging System with Fixed and Compact Optical Path, 2× Zoom Mechanism and Wide Variable Incident Angle

ZHANG Yi-Ming, CHEN Jun, LIAO Tao, XU Ji-Ying, CHEN Yi

2012, 33(02):  251-256.  doi:10.3969/j.issn.0251-0790.2012.02.007

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A new surface plasmon resonance imaging(SPRi) system was designed and fabricated using a right angle trapezoid prism as SPR coupler, which allows the fixation of left optical elements in a compact space and addition of a 1—2× zooming adjuster. This design simplifies the angle scanning mechanism, enables a very fine adjustment of incident angle from 40° to 80° at 0.001° angle resolution, and makes the observation possible of size-variable chips(1—4 cm²), providing a lateral spatial resolution up to 3600 Point/cm². Its sensiti-vity was evaluated with sucrose solutions, giving the data up to 7×10^-6 RIU(Refractive index unit). A linear relationship was obtained between resonance angle and sample refractive index, with correlation coefficients of 0.99953. The new system has been further validated in the immuno-reaction of BSA with anti-BSA, which enables to produce both of kinetic reaction curves and differentiated dot images. These results indicate that the newly designed SPRi system is highly promising for high-through binding affinity applications.



Elemental Signal Response of Sulfide Minerals in LA-ICP-MS Microanalysis

KE Yu-Qiu, ZHANG Lu-Yuan, CHAI Xin-Na, ZHENG Hong-Tao, JIN Lan-Lan, HU Sheng-Hong

2012, 33(02):  257-262.  doi:10.3969/j.issn.0251-0790.2012.02.008

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Five natural sulfide minerals were determined using laser ablation inductively coupled plasma mass spectrometry(LA-ICP-MS) with a 193 nm ArF excimer laser ablation system. Elemental fractionation effect and influences of spot size, repetition rate and laser energy on laser ablation behavior of different sulfides were investigated based on different laser ablation profiles and transient signal response. The results show that laser ablation characteristics and elemental fractionation effect of sulfides vary significantly with the physical properties and chemical components of sulfides. The ablation halos of pyrite, molybdenite and sphalerite are approximately 10 times the diameter of the corresponding spot size, whereas chalcopyrite and pyrrhotite are about 14 times. The elemental fractionation indexes(EFI) indicate that pyrite and molybdenite behave apparent elemental fractionation while chalcopyrite, pyrrhotite and sphalerite, EFI of which approached to 1.0, do not. For sulfide minerals microanalysis by LA-ICP-MS, accurate analysis results can be obtained under the laser ablation parameters of large spot size, low repetition rate and low laser energy.



Proton Transfer Reaction Mass Spectrometer with Multi-reagent Ions

SHEN Cheng-Yin, LI Jian-Quan, WANG Hong-Zhi, WANG Yu-Jie, WANG Hong-Mei, HUANG Chao-Qun, LI Hu, LIU Sheng, CHU Yan-Nan

2012, 33(02):  263-267.  doi:10.3969/j.issn.0251-0790.2012.02.009

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Clean sources of reagent ions H₃O⁺, NH₄⁺, NO⁺ and O₂⁺ were obtained in conventional proton transfer reaction mass spectrometry(PTR-MS) without any radioactive substance and any mass pre-selection. The intensity of these reagents is at 10⁵cps. Three kinds of new reagents, NH₄⁺, NO⁺ and O₂⁺ tested with some volatile organic compounds(VOCs) show different ionization characters. The isomers propanal and acetone were detected with reagent ions H₃O⁺, NH₄⁺, NO⁺ and O₂⁺. The results show that NO⁺ and O₂⁺ can discriminate propanal from acetone. New multi-reagent ions PTR-MS can detect more compounds, whose proton affinities(PA) are not always higher than that of H₂O(691.0 kJ/mol). And it is shown to be a more versatile technique than conventional PTR-MS with the potential for analysis of isocompounds.



Preparation of Multi-layer Open Capillary Immobilized Enzyme Reactor and Its Application in Digestion of Proteins

HU Jia-Wei, SHEN Ye-Hua, QIN Wei-Jie, ZHANG Yang-Jun, Qian Xiao-Hong

2012, 33(02):  268-275.  doi:10.3969/j.issn.0251-0790.2012.02.010

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With the capillary as the carrier of enzyme immobilization, poly(amidoamine) was gradually bon-ded to the inner wall of the capillary, then the trypsin was attached at the amino group of poly(amidoamine) with glutaraldehyde, and finally the multi-layer open capillary immobilized enzyme reactor was prepared after enzyme immobilization conditions had been optimized. Cyt-c was chosen as a model protein for evaluation of the performance of the multi-layer open capillary immobilized enzyme reactor, and its digestion conditions were optimized. The results demonstrate that the multi-layer immobilized enzyme reactor has high efficiency, good reproducibility and stability, and can be further applied in future proteomics study.



Organic Chemistry

Theoretical Study on the Thermodynamic Hydricity of Imidazole-based Organic Hydrides in Acetonitrile

YU Ao, WANG Hui-Kai, XUE Xiao-Song, CAI Yu, WANG Yong-Jian, HE Jia-Qi

2012, 33(02):  276-281.  doi:10.3969/j.issn.0251-0790.2012.02.011

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Theoretical thermodynamic hydricities of imidazole-based hydrides in acetonitrile were calculated by different methods. Compared with the available experimental values, it was found that the MP2/6-311++G^**//B3LYP/6-31+G^* protocol with the IEF-PCM(interval equation formalism-polarized continuam model) solvent model could predict the thermodynamic hydricity with a good precision. With this method, the thermodynamic hydricities of 14 imidazole-based organic hydrides(IHs) in acetonitrile were estimated. The results show that all of the properties of substituent, the aromatization ability of IH after releasing a hydride anion, the contribution from the frontier orbital of the 2-phenyl of imidazole to the whole frontier orbital of IH and IC(the cation of IH), the natural bond orbital(NBO) charge distribution and the solvent effect have influences on the thermodynamic hydricities of imidazole-based hydrides in acetonitrile.



Interaction of Cucurbit[n=7,8] uril with Ranitidine Hydrochloride and Slow Release Properties

LI Li-Fan, LIN You-Wen, HUANG Zhi-Wen, LUO Hong-Bin

2012, 33(02):  282-287.  doi:10.3969/j.issn.0251-0790.2012.02.012

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Cucurbit[n]urils(Q[n]) has hydrophobic central cavity and negatively charged carbonyl portals, can bind to a variety of cationic organic guest molecules and neutral species with high affinity, and therefore show great promise as a drug delivery system. In this work, interaction of cucurbit[n=7,8]urils with ranitidine hydrochloride(RH) which is a histamine H₂ receptor antagonists were investigated by means of ¹H NMR and UV-Vis spectroscopy, and the drug slow-release properties of inclusion complexes were observed in vitro. The effect of pH value on the interaction was studied; the inclusion ratio m, formation constant K_a and the drugs cumulative release of inclusion complexes in vitro were determined. The results reveal that RH form a 1∶1 complex with the Q[n](n=7,8). Formation constant of K_a was found to be 1.21×10⁴ and 2.06×10⁴ L/mol for Q[7]-RH and Q[8]-RH systems, respectively. RH can both form inclusion complexes with Q[7] and Q[8] in acidic, neutral conditions respectively, but they can't form inclusion complexes in alkaline conditions. The cumulative release rate in vitro of RH, Q[7]-RH and Q[8]-RH in artificial gastric juice(pH=1.2) at 60 min were 89.1%, 56.6% and 38.4%, respectively; and in artificial intestinal fluid(pH=6.8) at 60 min were found to be 90.2%, 58.7% and 38.0%, respectively. The drug release rates of Q[7]-RH and Q[8]-RH were obviously slower than that of RH. Q[7]-RH and Q[8]-RH had obviously sustained-release in vitro.



Mechanisms of the Oxidations of NAD(P)H Model Hantzsch 1,4-Dihydropyridines by 2-Nitro-2-nitrosopropane

LI Xin, DONG Nan, CHENG Jin-Pei

2012, 33(02):  288-291.  doi:10.3969/j.issn.0251-0790.2012.02.013

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Hantzsch 1,4-dihydropyridine derivatives which contain 1,4-dihydropyridine structure of natural reduced nicotinamide adenine dinucleotide[NAD(P)H] coenzyme and possess a high biological activity as a class of useful drugs, can be chosen as models of NAD(P)H to react with NO or its donor to mimic the oxidation of NAD(P)H by NO in vivo. Herein, 4-substituted derivatives of Hantzsch 1,4-dihydropyridine were treated by 2-nitro-2-nitrosopropane to give the corresponding pyridine derivatives. Replacement of HEH by N-d-HEH and 4,4'-2d-HEH to react with 2-nitro-2-nitrosopropane gave the observed kinetic isotope effects of 1.03 and 1.78. The study of the redox potentials(cyclic voltametry) of the two reactants indicated that the oxidation of HEH by 2-nitro-2-nitrosopropane initiated by one-electron transfer was extremely unfavorable in thermodynamics. In addition, the ineffectiveness of p-dinitrobenzene on the reaction can also support it. These results indicate that the oxidation of HEH by 2-nitro-2-nitrosopropane is initiated by nitrosation to give the corresponding N-nitroso compound, which is subsequently subjected to two steps of homolytic cleavage to afford the aromatized Hantzsch pyridine. We believe that the present work will stimulate the investigations of the chemical features of C-nitroso compounds and its role in biological and medicinal chemistry.



Supramolecular Self-assembly Between Viologen and Cucurbit[8]uril and Its Application for the DNA Photocleavage

ZHANG Tong-Yan, SUN Shi-Guo, PENG Xiao-Jun, TAO Bin-Bin

2012, 33(02):  292-297.  doi:10.3969/j.issn.0251-0790.2012.02.014

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Combining supramolecular chemistry with biochemistry was a new research direction. In this paper, self-assembly between a host compound CB[8] with a guest molecule benzyl viologen(BEV) was examined by UV absorption measurement, cyclic voltammetric method and ¹H NMR technique. The experimental results revealed that CB[8] included benzyl and part of pyridinum of BEV to form binary compounds BEV-CB[8], and when BEV²⁺ was reduced to BEV^+·, a new stable ternary complex (BEV^+·)₂/CB[8] would be formed. The two kinds of viologens, BEV and BEV-CB[8], were used for DNA photocleavage stu-dies in physiological environment following the research results that CB[8] could enhance the interaction between BEV and CT DNA with intercalation and electrostatic interaction. Only 50 μmol/L of the complex BEV-CB[8] could cleave SC pBR 322 DNA completely compared with BEV, which showed no ability for DNA clea-vage under the irradiation of Xe lamp. The main reason was that BEV²⁺ was reduced to BEV^+· under irradiation and CB[8] bound BEV^+· tightly to form (BEV^+·)₂/CB[8], which prolonged the lifetime of viologen radical BEV^+·, causing the dissolved oxygen in water activation and the reactive oxygen species, · OH and O₂^-·, could cleave SC pBR 322 DNA. The results indicate an important application by host molecule CB in supramolecular chemistry, which gives an obviously evidence for the field of DNA cleavage.



Design, Synthesis and Biological Activities of Amides(Sulfonamides) Containing N-Pyridylpyrazole

XU Jun-Ying, DONG Wei-Li, XIONG Li-Xia, LI Zheng-Ming

2012, 33(02):  298-302.  doi:10.3969/j.issn.0251-0790.2012.02.015

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Referring to the structure of Rynaxypyr^TM, a series of novel amides(sulfonamides) containing N-pyridylpyrazole was designed and synthesized. Their chemical structures were characterized by means of ¹H NMR and elemental analysis. The results of the biological assay show that some of the amide(subfonamides) exhibite good insecticidal activities against Oriental Armyworm(Mythimna separata Walker) and Culex pipiens pallens. The death rates for Oriental Armyworm of compounds 4a, 4k and 5b are all higher than 50% at 100 mg/L, and the death rate of compound 4g for Culex pipiens pallens was 100% at 2 mg/L.



Biological Chemistry

Purification of Histidine-tagged Fusion Proteins Based on Fe₃O₄@SiO₂/Ni-NTA Magnetic Spheres

WANG Wen-Jia, GUO Xiao-Lin, WEI An-Hui, FU Chang-Hao, HAN Zhen-Guo

2012, 33(02):  303-307.  doi:10.3969/j.issn.0251-0790.2012.02.016

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The development of reliable and efficient methods to separate proteins of interest from a biological source is still a challenging work. Currently, using the His-tagged fusion proteins to separate and purifiy proteins has been the most widely used technology. This study deals with the synthesis of Ni-nitrilotriacetic acid(Ni-NTA) modified Fe₃O₄@SiO₂ magnetic spheres, which can act as a general agent to separate and purify Histidine-tagged fusion proteins. The spheres have a core composed of carbon particles and a shell composed of Fe₃O₄ having a uniform size of ca.402 nm, which provides the spheres with excellent magnetic responsivity and dispersity. The recombinant proteins that had been engineered to have six consecutive histidine residues(6×His) were separated by means of Fe₃O₄@SiO₂/Ni-NTA magnetic spheres. The results show that 10 mg of Fe₃O₄@SiO₂/Ni-NTA spheres are able to purify about 1 mg of 6×His-tagged proteins from 10 mL crude E. coli. lysate. Owing to the high separation capacity, Fe₃O₄@SiO₂/Ni-NTA spheres can be used to separate 6×His-tagged proteins with low-concentrations.



Purification and Synthesis of ACE Inhibitory Peptide from Acaudina molpadioidea Protein Hydrolysate

ZHAO Yuan-Hui, LI Ba-Fang, MA Jing-Jun, DONG Shi-Yuan, LIU Zun-Ying, ZENG Ming-Yong

2012, 33(02):  308-312.  doi:10.3969/j.issn.0251-0790.2012.02.017

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A novel ACE inhibitory peptide was isolated from the sea cucumber(Acaudina molpadioidea) hydrolysate using the chromatographic methods including gel filtration, ion-exchange chromatography and reversed phase high-performance liquid chromatography. The purified ACE inhibitory peptide was sequenced as MEGAQEAQGD, with a IC₅₀ value of 15.9 μmol/L. The ACE inhibitory peptide was synthesized by a method of gradual condensation and fragmental condensation. The purity of the decapeptide was 99.72%, and the molecular weight and sequence structure of the decapeptide equate with the fact. It was found that the inhibitory activity of the peptide was intensified by 3.5 times after incubation with pepsin and chymotrypsin. The ACE inhibitory peptide from Acaudina molpadioidea showed a clear antihypertensive effect on spontaneously hypertensive rats(SHR), at a dosage of 3 μmol/kg.



Screen and Verification of Interactive Protein of Selenoprotein K in Human Liver

LIANG Xue-Ying, LIU Qiong, CHEN Ping, HUO Ke-Ke, HU Tian-Yong, NI Jia-Zuan

2012, 33(02):  313-320.  doi:10.3969/j.issn.0251-0790.2012.02.018

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Selenium, an essential trace element for human health, plays important roles in maintaining redox balance in vivo. Selenium deficiency is associated with many diseases, such as cancer, neurodegenerative diseases and cardiovascular diseases. The biological function of selenium in vivo is mainly exerted through selenoproteins. Selenoprotein K(SelK) is a newly discovered selenoprotein with unknown biological function and molecular mechanism. In this work, human SelK gene was cloned, site-directedly mutated and inserted into the "bait" plasmid to screen the human liver cDNA library using the yeast two-hybrid system. An interactive protein, homo sapiens cAMP responsive element binding protein 3(CREB3), was screened out and analyzed. SelK' and CREB3 genes were then co-transformed into yeast cells to verify the protein interaction, followed by the co-transfection into HEK293T cells to further verify the interaction via three methods of fluorescence resonance energy transfer technique, including the receptor photobleaching, sensitized emission and fluorescence lifetime. The results show that SelK interacte with CREB3 independent of its selenocysteine residue. By interacting with CREB3, SelK may participate in CREB3-mediated endoplasmic reticulum-asso-ciated degradation and make impact on cancer migration and development.



Physical Chemistry

Self-supporting Macroscopic Carbon Nanotubes Microfiber Hybrid Electrodes for Capacitive Deionization

WANG Xi-Wen, JIANG Fang-Ting, SUO Quan-Ling, FANG Yu-Zhu, LU Yong

2012, 33(02):  321-326.  doi:10.3969/j.issn.0251-0790.2012.02.019

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A promising self-supporting macroscopic carbon nanotubes(CNTs) electrode was prepared by catalytic chemical vapor deposition method through CNTs growth on a three-dimensional network of sinter-locked conductive 8 μm-nickel fibers, namely CNTs/SMF-Ni(CNTs mass fraction 50%), in which the Ni-microfibrous network serves as current collector and CNTs as ion storage reservoir. This approach permits the desirable large area fabrication and unique combinations of binderlessness, excellent thermal/electrical conductivity, macro-/meso-sized hierarchical porous structure, and individual/uniform dispersion of CNTs. This CNTs electrode was characterized by scanning electron microscopy(SEM), transmission electron microscopy(TEM), Fourier transform infared spectrometry(FTIR), N₂ isothermal adsorption-desorption and X-ray diffraction. The desalination performance for 0.01%NaCl aqueous solution was tested using the CNTs/SMF-Ni as the electrodes of the capacitive deionization. Owing to the excellent ion diffusivity, high conductivity and high mesopore surface area, such hybrid electrodes delivered the maximum electrosorption capacity of 159 μmol/g CNTs with a salt removal rate of 57%, using the direct current voltage of 1.2 V and water flow rate of 5 mL/min. The desalination performance of such hybrid electrodes could be further promoted by oxidation treatment using H₂O₂ solution, due to significantly enhanced hydrophilicity stemmed from formation of large amount of O-containing groups on the CNTs surface.



Electrochemical Behavior of Mn(Ⅱ) in the Melt LiCl-KCl-MgCl₂-MnCl₂

CHEN Li-Jun, ZHANG Mi-Lin, HAN Wei, YAN Yong-De, CAO Peng

2012, 33(02):  327-330.  doi:10.3969/j.issn.0251-0790.2012.02.020

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The reduction of Mn(Ⅱ) on a molybdenum electrode in the melt LiCl-KCl-MgCl₂-MnCl₂ at 898 K and the conditions of the co-deposition of Mg-Li-Mn alloys were investigated. Cyclic voltammetry and chronopotentiometry show that the reductions of Mn(Ⅱ), Mg(Ⅱ) and Li(Ⅰ) start at -1.14, -1.78 and -2.19 V, respectively. And the underpotential deposition of magnesium on pre-deposited manganese leads to the formation of a liquid Mg-Mn solution, then a liquid Mg-Li-Mn solution forms for the succeeding underpotential deposition of lithium on pre-deposited Mg-Mn. The diffusion coefficient of Mn(Ⅱ) in the melts was also calculated with different methods, which was about 10^-5 cm²/s. The analysis of X-ray diffraction indicats that there are three phases(β-Li, α-Mg and Mn) in the Mg-Li-Mn alloy.



Electrooxidation of Formic Acid on Palladium Nanoparticles Supported on Ordered Mesoporous Carbon

CHEN Ming-Hui, HE Chun-Lan, ZHANG Bin-Wei, JIANG Yan-Xia, CHEN Sheng-Pei, SUN Shi-Gang

2012, 33(02):  331-335.  doi:10.3969/j.issn.0251-0790.2012.02.021

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Ordered mesoporous carbon(MPC) supported palladium catalysts were prepared by impregnation(MPC/Pd-1) and the method of using sulfur to embed noble metal[MPC/(S)Pd-2], respectively. The properties of the MPC/Pd were investigated by XRD, HRTEM, BET and electrochemical methods. Cyclic voltammetry and current-time curve show that MPC/Pd exhibits a very high catalytic activity for the oxidation of formic acid, which is 4.0(MPC/Pd-1) and 2.4 times[MPC/(S)Pd-2] that of commercial Pd black. Pd nanoparticles on MPC/Pd-1 are confined in the pores of MPC(5—6 nm), which increases the reaction interfaces of the three-phase boundary(catalyst-electrolyte-reactive), whereas Pd nanoparticles on MPC/(S)Pd-2 are loaded inside the small mesoporous of the pore wall(2—3 nm), which decreases utilization of the catalyst.



Electrochemical Study of Au@Pt Nanoparticles for Oxygen Reduction Reaction

DENG Xiao-Cong, TIAN Xiang-Dong, WEN Fei-Peng, YI Fei, CHENG Mei-Qin, ZHONG Qi-Ling, YAN Jia-Wei, REN Bin, TIAN Zhong-Qun

2012, 33(02):  336-340.  doi:10.3969/j.issn.0251-0790.2012.02.022

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Core-shell nanostructure Au@Pt nanoparticles were synthesized with a diameter of 100 nm Au nanoparticles as cores, ascorbic acid as reducing agent and H₂PtCl₆@6H₂O as the precursor. The synthesized nanoparticles and commercial electrocatalysts were dropped on glassy carbon electrodes(Au@Pt/GC) to form the oxygen reduction electrodes(Au@Pt/GC, Pt/C/GC). The reaction activities for oxygen reduction and methanol tolerance of Au@Pt/GC and commercial Pt/C/GC electrodes were compared with those of rotating disk electrode and other conventional electrochemical methods. At a significantly reduced amount of Pt, the oxygen reduction activity of Au@Pt nanoparticles is still comparable with the commercial Pt/C. The oxygen reduction proceeds via a four-electron transfer reaction to water on Au@Pt nanoparticles. Futhermore, it shows a good tolerance to methanol.



Combustion Mechanism of n-Decane at High Temperatures and Kinetic Modeling of Ignition Delay for Aviation Kerosene

WANG Hui-Ru, JIN Jie, WANG Jing-Bo, TAN Ning-Xin, LI Xiang-Yuan

2012, 33(02):  341-345.  doi:10.3969/j.issn.0251-0790.2012.02.023

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A detailed mechanism for the combustion of n-decane, which is the single surrogate component of the Chinese aviation kerosene, was constructed by our program ReaxGen-Combustion for automatically generating reaction mechanisms of hydrocarbon fuels. Then referencing the observations of the Chinese aviation kerosene in the heating-up shock wave tube reactor, contrast studies were done on the reliability of the follo-wing models predicting the ignition delay behavior of gas-phase Chinese aviation kerosene: the three-component surrogate model(model Ⅰ), the two-component surrogate model(model Ⅱ), and the present single surrogate model(model Ⅲ). The results show that the ignition delay time predicted by model Ⅰ is in bad agreement with the observations during the temperature range of 1052-1538 K; model Ⅲ can give reasonable ignition delay time when the temperature is higher than 1176 K, but give results different from the observations in the range of 1052-1176 K; the ignition delay time predicted by model Ⅱ is close to those by model Ⅲ, however, the former takes the low-temperature mechanisms into account, so can give better results than model Ⅲ in the range of 1052-1176 K, though still different from the observations. In addition, the additive 20%(mass fraction) of 1,2,4-trimethylbenzene in model Ⅱ has little effect on the ignition delay time at high temperature.



Improving the Accuracy of DFT Calculation for Homolysis Bond Dissociation Energies of Y—NO Bond via Back Propagation Neural Network Based on Mean Impact Value

LI Hong-Zhi, TAO Wei, GAO Ting, LI Hui, LV Ying-Hua, SU Zhong-Min

2012, 33(02):  346-352.  doi:10.3969/j.issn.0251-0790.2012.02.024

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The back propagation neural network(BPNN) approach based on mean impact value(MIV)(MIV-BPNN) was used to improve the accuracy of density functional theory(DFT) calculation for homolysis bond dissociation energies of Y—NO bond. Quantum chemistry calculations and MIV-BPNN were used jointly to calculate the homolysis bond dissociation energy(BDE) of 92 Y—NO organic molecular systems. The results show that compared to a single density functional theory B3LYP/6-31G(d) approach, full parameters BPNN approach reduces the root-mean-square(RMS) of the calculated homolysis BDE of 92 organic molecules from 22.25 kJ/mol to 1.84 kJ/mol and MIV-BPNN approach further reduces the RMS to 1.36 kJ/mol. It is clear that the combined B3LYP/6-31G(d) and MIV-BPNN approach can improve the accuracy of the homolysis BDE calculation in quantum chemistry and can predict homolysis BDE which can not be obtained experimentally.



Preparation and Non-isothermal Kinetics of Thermal Decomposition of AgO-loaded Diatomite Composite

SHEN Wen-Ning, FENG La-Jun, FENG Hui

2012, 33(02):  353-360.  doi:10.3969/j.issn.0251-0790.2012.02.025

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AgO-loaded diatomite composite was prepared by chemical oxidation-deposit method using potassium persulfate as oxidant. The composite was characterized by X-ray diffraction, scanning electron microscope and the laser particle size analyzer. The process and kinetic behavior of thermal decomposition of the composite were studied by means of thermogravimetry. The results show that the AgO-loaded diatomite composite with a AgO content(mass fraction) of 12.7% is made up of tetragonal christobalite and monoclinic silver peroxide. The size of the composite is in the range of 0.614—116.5 μm and the median-particle-size and specific surface area of the composite are 18.53 μm and 203.32 m²/kg, respectively. The composite decomposes at 171 ℃ along with the formation of silver oxide followed by decomposing into silver at higher temperature. The mechanism of decomposition reaction is random nucleation and subsequent growth mechanism(A1), and the apparent activation energy and reaction frequency factor are 131.37 kJ/mol and 3.19×10¹³ s^-1, respectively. Compared with reference silver peroxide powders, the thermal decomposition temperature of the composite rises and a considerable increase of the activation energy up to 40 kJ/mol was observed.



Fabrication of Inverted Pyramidal Microstructures with Antireflective Properties

HAO Juan-Ting, HE Da-Cheng, HAO Juan-Yuan

2012, 33(02):  361-364.  doi:10.3969/j.issn.0251-0790.2012.02.026

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The inverted pyramidal microstructures were fabricated by anisotropic wet etching on the domain structure patterned Si substrate, which was obtained by transferring stearic acid monolayer onto Si substrate via Langmuir-Blodgett(LB) technique. The height of inverted pyramidal structures and the antireflective properties were mainly dependent on etching duration. This method combines the simplicity and scalability of self-assembly and low cost of chemical etching. It is an inexpensive and effective method to fabricate antireflective surface over large area, which has potential applications on reducing the cost of optical devices and solar cells.



Preparation of Mg-Al Mixed Oxide Supported Nickel Catalysts and Their Catalytic Activities in Low Temperature Reforming of Liquified Petroleum Gas

SHEN Kui, WANG Xue-Guang, WANG Xin-Xing, ZOU Xiu-Jing, LU Xiong-Gang, DING Wei-Zhong

2012, 33(02):  365-372.  doi:10.3969/j.issn.0251-0790.2012.02.027

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Ni/Mg(Al)O catalysts with different mass fractions of Ni were prepared by co-precipitation-impregnation method and used for low temperature steam reforming of liquified petroleum gas(LPG). X-ray diffraction and temperature-programmed reduction results showed that in the Ni/Mg(Al)O catalysts calcined at 800 ℃ Mg-Ni-O solid solution was formed, which could be reduced to produce metal Ni nanoparticles. The effects of Ni loading, reaction temperature and steam/carbon(n_H2O/n_C) ratio on the catalytic performance were discussed in detail. The experimental results revealed that the 15%Ni/Mg(Al)O catalyst showed the optimal catalytic performance. Elevating reaction temperature could remarkably enhance the catalytic activity of the Ni/Mg(Al)O catalysts. In the temperature range of 400-500 ℃ and at n_H2O/n_C=2, the highest space velo-city for completely converting LPG was enhanced from 28900 mL·h^-1·g^-1Cat to 86800 mL·h^-1·g^-1Cat. The proper increase in n_H2O/n_C favored reforming of LPG to small gas molecules. However, excessive amount of steam led to the decrease in LPG conversion when LPG molar flow rate was kept constant. The XRD and TG analyses showed that the excellent catalytic activity and stability of the used Ni/Mg(Al)O catalyst could likely be due to highly stable Ni crystallites on the catalyst surface and good resistance to carbon deposition.



Catalytic Properties of Cobalt Tetracarbonyl/Imidazolium Ionic Liquids in the Synthesis of Dimethyl Manolate by Carbonylation

JIANG Wen-Jie, MO Wan-Ling, JIA Yong-Mei, LI Guang-Xing

2012, 33(02):  373-377.  doi:10.3969/j.issn.0251-0790.2012.02.028

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A series of [Co(Co)₄]^-/imidazolium ionic liquids was synthesized, and their catalytic properties were evaluated in the carbonylation reaction of methyl chloroacetate. The effect of imidazolium with different branched chains on the catalytic properties of [Co(Co)₄]^- species was investigated. The experimental results show that 1-butyl-3-methylimidazolium cobalt tetracarbonyl([Bmim][Co(Co)₄]) is an efficient and reusable catalyst for the carbonylation of methyl chloroacetate. At reaction conditions of p_CO=2 MPa, 85 ℃, and t=3 h, the average conversion of methyl chloroacetate was 94.3%, the average selectivity to malonic ester was 98.5% and the average yield of dimethyl malonate was 92.9% for [Bmim][Co(Co)₄] catalyst at four recycles. Compared with the traditional Na[Co(Co)₄] catalyst, [Bmim][Co(Co)₄]catalyst exhibited high activity and good reusability, which could be mostly attributed to the good stability for air of the versatile [Co(Co)₄]^- species at the circumstance of imidazolium ionic liquids.



Gd³⁺ and RGD Functionalized Quantum Dots for Fluorescent and MR Dual-modality Imaging of Pancreatic Cancer Cells

LIU Feng-Jun, ZHANG Bing-Bo, SONG Ge, CHENG Ying-Sheng

2012, 33(02):  378-382.  doi:10.3969/j.issn.0251-0790.2012.02.029

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Though early diagnosis of pancreatic cancer is difficult, it brings challenges and opportunities to the molecular imaging. The existing diagnostic imaging technologies are limited as a result of single functiona-lity, making it difficult for accurate diagnosis. In this work, magnetic resonance image(MRI) and fluorescence imaging were combined by several key contrast agents including gadolinium ion, quantum dots(QDs) and arginine(R)-glycine(G)-D-aspartic acid(D)(RGD) for high relaxation rate, strong fluorescent emission and good targeting. The integrated dual-modality QDs@Gd³⁺-RGD nanoprobes were used for dual-modality imaging of pancreatic cancer cells. TEM and dynamic light scattering(DLS) results indicate complete dispersion of QDs@Gd³⁺-RGD nanoprobes in water. In vitro relaxivity measurement shows high relaxation rate of QDs@Gd³⁺-RGD nanoprobes. Their r₁ and r₂ are 7.6 and 9.5 L@mmol^-1@s^-1, respectively. Fluorescent and MR dual-modality imaging suggest the prepared QDs@Gd³⁺-RGD nanoprobes can sever as both fluorescent and MR imaging of patu8988 pancreatic cancer cells.



Investigation of Selectivity over HDS Catalysts by in situ IR Spectra of Adsorbed CO and Molecular Simulation Calculation

QIHE Ri-Ma, ZHAO Xiao-Guang, ZHANG Yun-Hong, YUAN Hui, XU Guang-Tong

2012, 33(02):  383-388.  doi:10.3969/j.issn.0251-0790.2012.02.030

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Two CoMo/Al₂O₃ catalysts with different supports(Al₂O₃-A and Al₂O₃-B) were prepared by pore-filling impregnation. Active phases of the sulfided CoMo/Al₂O₃ catalysts were identified and analyzed quantitatively by means of in situ FTIR spectrum of adsorbed CO. The charge distribution, adsorption energy and activation energies of hydrotreating reaction of thiophene and 1-hexene on the MoS₂ surface before and after adding Co were calculated by molecular simulation, respectively. The results reveal that the increase of CoMoS phase on the catalyst surface improves the HDS/HYD selectivity. Compared with HYD site of 1-hexene, the electron accepting ability of thiophene HDS site can be improved significantly by the adding of Co support, which benefits to improve the adsorptions of thiophene on the surface over catalyst and decrease the activation energy barrier of HDS for thiophene. This fact also points out that the CoMoS phase is the active site of high HDS and HDS/HYD selectivity.



Polymer Chemistry

Preparation and Characterization of Gelatin/PLLA Composite Fibrous Scaffold and Evaluation for Corneal Cells Supports

YAN Jing, GAO Yan, WANG Qing, CUI Xue-Jun, ZHONG Shuang-Ling, WANG Ping, WANG Hong-Yan

2012, 33(02):  389-394.  doi:10.3969/j.issn.0251-0790.2012.02.031

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Gelatin and polylactic acid(PLLA) composite membranes were obtained via electrospun. The membranes composition on the surface properties, pore structure and mechanical properties were studied. The membranes were further used as scaffolds for rabbit corneal epithelial cells culture in vitro. The adhesion and proliferation of cells on these scaffolds were evaluated by immunofluorescence staining and thiazolyl bule tetrazolium bromide(MTT) assay. The results show that the fiber diameter distribution and surface hydrophilicity are significantly affected by composition of electrospinning solution. All of these scaffolds have high porosity and inter-connected pores. Gelatin could maintain high cell adhesion while PLLA improved mechanical properties of the composited scaffolds.



Properties of Microemulsion Formed by Different Alkyl Aryl Sulfonates

ZHANG Zhi-Wei, DING Wei, LI Zhong, DONG Zhi-Long, YU Tao, QU Guang-Miao, WANG Hui-Min, LUO Shi-Qiong

2012, 33(02):  395-399.  doi:10.3969/j.issn.0251-0790.2012.02.032

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The properties of microemulsion formed by three alkyl aryl sulfonates(synthesized in the laboratory) in the multi-component systems were investigated by Winsor phase diagram and pseudo-ternary phase diagram methods. The influences of molecular structure, inorganic salt and short chain alcohol on these microemulsion properties were discussed, respectively. The results show that as the concentration of inorganic salt increases, the surfactants/n-butanol/n-octane/NaCl/water microemulsion systems transform from WinsorⅠ to Winsor Ⅲ and then to WinsorⅡ at certain temperature. With the increase of the number of long alkyl carbon atoms in alkyl aryl sulfonate molecule, the salt-toleran ability decreases but the solubilization capacity increases. With the increase of carbon atom number of the alcohol, the area of microemulsion region increases first and then decreases. When molecular structure of alkyl aryl sulfonate is fixed, the choice of alcohol is based on Bansal theory for the biggest microemulsion region. When the chain length of alcohol is determined, with the increase of the number of long alkyl carbon atoms in alkyl aryl sulfonate molecule, the area of microemulsion region will decrease.



Properties of Poly(lactic acid) Toughened by Epoxy-functionalized Elastomer

FENG Yu-Lin, YIN Jing-Hua, JIANG Wei, ZHAO Gui-Yan

2012, 33(02):  400-403.  doi:10.3969/j.issn.0251-0790.2012.02.033

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Poly(lactic acid)(PLA) was toughened by reactive blending with epoxy-functionalized elastomer glycidyl methacrylate grafted poly (ethylene octane)(POE-g-GMA) and ethylene-methyl acrylate-glycidyl methacrylate random terpolymer(E-MA-GMA). The result shows that POE-g-GMA is more effective than E-MA-GMA to toughen PLA. When the mass fraction of POE-g-GMA is 15%(mass fraction), the notched impact strength of the PLA/POE-g-GMA blend is as high as 72.5 kJ/m², while the impact strength of PLA/E-MA-GMA blend is only 32.4 kJ/m² when the E-MA-GMA is 15%(mass fraction). The scanning electron microscopy displayed better interfacial adhesion for PLA/POE-g-GMA blends than PLA/E-MA-GMA, which was well consistent with their results of mechanical properties.



Construction of Biomimetic Cross-linking Polyplexes with Thiolated-HA Shielding

XU Zhi-Xue, YANG Lu, TANG San, HU Qiao-Ling, WANG You-Xiang

2012, 33(02):  404-408.  doi:10.3969/j.issn.0251-0790.2012.02.034

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The preparation of biomimetic cross-linking polyplexes was an effective way to solve the contradiction between extracellular stability and intracellular dissociation of polyplexes. In this research, thiolated-HA(hyaluronic acid) was synthesized and then added to PEI[poly(ethleneimine)]/DNA polyplexes. Due to the electrostatic attraction, cross-linking polyplexes via disulfide bonds were constructed. Gel retardation assay indicated that these ternary polyplexes showed efficient DNA condensation ability. The biomimetic cross-linking shell improved the stability in physiological salt condition. The in vitro cell culture indicated that the cross-linking polyplexes reduced cytotoxicity and showed efficient transfection efficiency. This facile approach to constructing biomimetic cross-linking polyplexes might have great potential application in non-viral gene delivery research.



Rheological Properties of New Stimuli-responsive Energetic Gels

LÜ Shao-Yi, SHAO Zi-Qiang, ZHANG Zhen-Ling, WANG Fei-Jun, WANG Wen-Jun

2012, 33(02):  409-415.  doi:10.3969/j.issn.0251-0790.2012.02.035

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The relationships between the microstructure and the rheological behavior of energetic gels prepared by carboxymethyl cellulose nitrate(CMCN) of different content group as a gelator were investigated. The yield stress, thixotropy, creep and thermosensitivity of energetic gels were investigated by linear rheological methods and the gel mechanism was discussed. The flow data, creep data and angular frequency data of gels were fitted by Herschel-Bulkley model, Burger model and Carreau-Yasuda model, respectively. The experimental results show that CMCN gel is a physical gel with a relative homogeneous crosslinking network structure which is formed by non-covalent interaction of interchain hydrogen bonds and hydrophobic bonds on the group of amphiphilic CMCN. The non-Newton coefficients n of CMCN gels are all less than 0.5. With the increase of the content of hydrophilic carboxylic group, the yield stress and thixotropy recovery of gels increase gradually. The elastic compliance and viscous compliance of gel decrease while the ratio between them increase.The creep viscous responsivity decrease while elastic responsivity increase. The thermosensitivity of gels have a mechanical relaxation transition region which become more clearly with the increase of the content of carboxylic group, and thermosensitivity of gels increase.



Enzymatic Biodegradation and Thermal Properties of Phosphorylcholine Functionalized Poly(butylene succinate)

ZHANG Shi-Ping, WANG Dan, DANG Yuan, SHI Su-Qing, GONG Yong-Kuan

2012, 33(02):  416-420.  doi:10.3969/j.issn.0251-0790.2012.02.036

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Enzymatic degradation of poly(butylene succinate)(PBS) and phosphorylcholine functionalized poly(butylene succinate)(PBS-PC) were performed in the presence of lipase AY30. It was found that PBS-PC was effectively biodegraded by lipase AY30, and PBS was hardly degraded even after an experimental time scale of 21 d. By means of differential scanning calorimetry(DSC), thermal properties of PBS and PBS-PC were studied. The results show that the melting point(T_m) of PBS-PC is decreased and glass transition tempe-rature(T_g) is increased compared with unmodified PBS. PBS-PC may have potential applications in biological environments as new carriers for controlled drug release, gene therapy, and scaffold for tissue engineering systems.



Preparation and Characterization of Polyaniline Film by Potentiostatic Pulse Method

WANG Hong-Zhi, LIU Wei-Hong, LI Jian, YAO Su-Wei, ZHANG Wei-Guo

2012, 33(02):  421-425.  doi:10.3969/j.issn.0251-0790.2012.02.037

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The polyaniline(PANI) films were prepared by constant potential pulse method. The morphology, structure and optic properties of the films were characterized by scanning electron microscopy(SEM), X-ray diffraction(XRD), infrared ray(IR) and luminescence spectrum. We investigated the impact of duty cycle, cycle and pulse time on the morphology of films. The SEM images show that the grain size of films decreases with the decreases of the duty cycle; with the increase of cycles, the lamellar structure films change to granular structure which is longitudinal growth. The luminescence spectrum revealed that the emitting peak of the PANI films located at about 520 nm, and the luminescent intensity increases with the increase of the duty cycle. Electrochemical performance test shows that the PANI films which prepared by constant potential pulse method has good capacitive characteristics.



Synthesis and Properties of a Novel Contrast Agent

YANG Xiao-Lu, YANG Xing-Wang, HUANG Yan, ZHANG Qi, WU Jing-Bo, CAO Ben-Nan, ZHANG Xiao-Yan

2012, 33(02):  426-429.  doi:10.3969/j.issn.0251-0790.2012.02.038

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Chitosan oligosaccharides(CS_n, n=6, 8, 11) with narrow molecular weight distribution and low polymerization degree were introduced into diethylenetriamine pentaacetic(DTPA) by acylation reaction. The synthesized novel ligands were coordinated to Mn²⁺, then the paramagnetic Mn²⁺-based complexes were gained. The structures of synthesized ligands and the corresponding complexes were characterized by IR, elemental analysis, and ICP-AES. The longitudinal relaxivities(r₁) were measured. The results show that r₁ of Mn-DTPA-CS_n are higher than that of commercial contrast agent Gd-DTPA. Besides, the thermodynamical parameters of the interaction between the functional complexes and bovine serum albumin(BSA) were conducted by isothermal titration calorimetry(ITC).



Rheological Behavior of Impact Polypropylene Copolymer and Its Fractions

ZHANG Chun-Hui, SHANGGUAN Yong-Gang, TAN Ye-Qiang, CHEN Feng, HUANG Zhen-Zhi, ZHENG Qiang

2012, 33(02):  430-436.  doi:10.3969/j.issn.0251-0790.2012.02.039

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The dynamic rheological behavior of the melts for an impact propylene copolymer(IPC) and its three fractions were examined. The results show that the dynamic storage modulus(G') of IPC exhibits "pseudo solid-like" behavior at low frequency(ω), i.e. a "second plateau" appears in the lgG' vs. lgω plotting. This phenomenon indicates that the IPC melt is endowed with a characteristic of heterogeneous phase. The differences in G' and complex viscosity(η^*) among the fractions of IPC appear dramatic, which are probably induced by the differences of the molecular weight and the length of the molecular chains among the fractions. The dynamic rheological behavior of the EPR and HPP fractions well accord with the linear viscoelasticity, implying that these fractions are homogeneous system. Moreover, the dynamic rheological behavior of the EbP exhibits "pseudo solid-like" behavior at low ω, meaning that this fraction is a heterogeneous system. On the other hand, the "second plateau" can be observed in low ω region for the HPP/EPR blends when the proportion of the EPR is the same as the proportion of EPR in IPC, suggesting that the "second plateau" in IPC results from the phase-separation between HPP and EPR, and the existence of EbP does not play a key role in the generation of "second plateau" in IPC.