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Synthesis of Cyclic Oligo(ethylene adipate)s and Their Melt Polymerization to Poly(ethylene adipate)

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Chinese Journal of Polymer Science 2017年第9期35卷 1051-1060页

作者： min lu xiang zhu xiao-hong li xiao-ming yang 屠迎锋 Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials College of Chemistry Chemical Engineering and Materials Science Soochow University Suzhou 215123 China

We present here the first synthesis of cyclic oligo（ethylene adipate）s （COEAs） via pseudo-high dilution condensation reaction of adipoyl chloride with ethylene glycol, and the synthesis of corresponding poly（ethylene adipate）（PEA） via the melt polymerization of COEAs. The structure of COEAs was characterized and proved by 1H-NMR and MALDI-TOF mass measurements. The effects of organic base, reaction temperature and the ratio of adipoyl chloride to ethylene glycol on the yield of COEAs were studied, and the optimum reaction condition was revealed. PEA, a diacid and diol based semi-crystalline green aliphatic polyester, was synthesized by the melt polymerization of COEAs using Ti（n-C4H90）4 as catalyst and 1,10-decanediol as initiator at 200 ℃, which follows the polycondensation-coupling ring- opening polymerization method. Our strategy should be applicable to the synthesis of versatile aliphatic polyesters based on diacid and diol monomers, which have potential applications as biocompatible and biodegradable materials.

关键词： Cyclic oligoesters Pseudo-high dilution reaction condition Polycondensation-coupling ring-openingpolymerization Aliphatic polyesters

Thermodynamics of Aromatic Cyclic Ester Polymerization in Bulk

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Chinese Journal of Polymer Science 2019年第1期37卷 89-93页

作者： Chong He Xiang Zhu xiao-Hong Li xiao-ming yang Ying-Feng Tu Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application College of Chemistry Chemical Engineering and Materials ScienceSoochow University

We present here the thermodynamic investigation of in situ cascade polycondensation-coupling ring-opening polymerization(PROP)for three cyclic aromatic ester monomers,i.e.,cyclic oligo(2-methyl-1,3-propylene terephthalate)s(COMPTs),cyclic oligo(neopentylene terephthalate)s(CONTs)and cyclic oligo(2-methyl-2-propyl-1,3-propylene terephthalate)s(COMPPTs).The equibrium monomer to polymer weight ratio in bulk at different polymerization temperatures for each monomer was estimated by the size exclusion chromatography(SEC),and the thermodynamic parameters were estimated by Dainton *** different from the thermodynamics of aliphatic lactones polymerization,which is an exothermic process with entropy reduction,our results showed the polymerization thermodynamics for three cyclic aromatic ester monomers was a weak exothermic process with slight entropy increment,i.e.,a both enthalpy and entropy driving *** them,CONTs showed the largest value of enthalpy change,due to its symmetric dimethyl substitution onβ-position of propandiol segments.

关键词： Lactone Polyester Polycondensation-coupling ring-opening polymerization Thermodynamic parameters

Pricing in combinatorial double auction-based grid allocation model

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The Journal of China Universities of Posts and Telecommunications 2009年第3期16卷 59-65页

作者： LI Li LIU Yuan-an LIU Kai-ming MA xiao-lei yang ming Key Laboratory of Universal Wireless Communications Ministry of Education Beijing University of Posts and Telecommunications Beijing 100876 China

This article proposes a novel grid resource allocation model, in which the users and the grid service providers participate in the combinatorial double auction for the resource allocation. To obtain the detailed resource allocation status and the price information, a novel pricing algorithm is designed for the allocation model. Simulation results demonstrate that the proposed algorithm completes the resource allocation and pricing efficiently, and exhibits incentive compatible characteristic. Moreover, users with the higher average price and providers with the lower average price get compensation during the pricing process.

关键词： grid combinatorial double auction resource allocation pricing

Non-line-of-sight error mitigating algorithm based on scattering models via multi-antenna system

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The Journal of China Universities of Posts and Telecommunications 2008年第1期15卷 18-22页

作者： ZHU xiao-xuan SHI ming-yang ZHANG Jing TAO xiao-feng Key Laboratory of Universal Wireless Communications Beijing University of Posts and Telecommunications Ministry of Education Wireless Technology Innovation Institute (WTI) Beijing 100876 China

In urban environment with serious blocking of direct paths, the non-line-of-sight （NLOS） propagation influences the location estimation accuracy. In this article, a novel algorithm is developed, which can mitigate the NLOS errors in location estimation significantly. Utilizing multiantenna array, the information of scatterers that cause the NLOS propagation is obtained. Then, we combine the information with TOA/TDOA based location algorithm to estimate the location of mobile station （MS）. The simulation results show that our method can mitigate NLOS errors and enhance the location accuracy greatly.

关键词： multi-antenna location algorithm NLOS time of arrival (TOA)

Hydrogen peroxide biosensor based on electrodeposition of zinc oxide nanoflowers onto carbon nanotubes film electrode

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Chinese Chemical Letters 2008年第3期19卷 314-318页

作者： Hui Ping Bai Xu xiao Lu Guang ming yang Yun Hui yang Department of Chemistry and Chemical Engineering Yunnan Normal University Kunming 650092 China

A new amperometric biosensor for hydrogen peroxide was developed based on adsorption of horseradish peroxidase at the glassy carbon electrode modified with zinc oxide nanoflowers produced by electrodeposition onto multi-walled carbon nanotubes （MWNTs） film. The morphology of the MWNTs/nano-ZnO electrode has been investigated by scanning electron microscopy （SEM）, and the electrochemical performance of the electrode has also been studied by amperometric method. The resulting electrode offered an excellent detection for hydrogen peroxide at -0.11 V with a linear response range of 9.9×10^-7 to 2.9×10^-3 mol/L with a correlation coefficient of 0.991, and response time 〈5 s. The biosensor displays rapid response and expanded linear response range, and excellent stability.

关键词： Multi-walled carbon nanotubes Biosensor Electrodeposition Horseradish peroxidase ZnO nanoflowers

Physiological Responses of Limonium aureum Seeds to Ultra-drying

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Journal of Integrative Plant Biology 2007年第5期49卷 569-575页

作者： Yi Li Hu-Yuan Feng Tuo Chen xiao-ming yang Li-Zhe An School of Life Sciences Lanzhou University Lanzhou 730000 China Cold and Arid Region Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou 730000 China

The seeds of Limonium aureum （L.） Hill. were dried from 8.92% to 2.88% moisture content in a desiccating container with silica gel. After ultra-drying the seeds were accelerated aged （50 ℃, 1 month）, and some physiological indices, including the electrical conductivity, dehydrogenase activity, superoxide dismutase （SOD）, peroxidase （POD）, glutathione reductase （GR）, ascorbate peroxidase （APX）, catalase （CAT）, volatile aldehydes and malondialdehyde （MDA） were tested. The results indicated that dehydrogenase, POD, SOD, GR, APX and CAT activities of the ultra-dry seeds were higher than the control seeds, while volatile aldehydes and malondialdehyde were lower than the control group. The results suggest that ultra-drying is beneficial for maintaining the vigor of L. aureum seeds at a high level. Thus, L. aureum seeds could be stored under ultra-dry conditions.

关键词： electrical conductivity Limonium aureum seed physiological indices ultra-dry.

Crystalline-amorphous M@MN_x(M=Co,Fe,Ni)encapsulated in nitrogen-doped carbon for enhanced efficient and durable hydrogen evolution reaction

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Rare Metals 2024年第4期43卷 1547-1556页

作者： yang yang xiao-Chuan Duan Shao-Hui Guo Xian-ming Zhang College of Materials Science and Engineering College of ChemistryKey Laboratory of Interface Science and Engineering in Advanced MaterialsTaiyuan University of TechnologyYuci030600China

Developing earth-abundant electrocatalysts for hydrogen evolution reaction(HER)is important for the sustainable energy ***,efficient and stable heterocatalysts consisting of crystalline-amorphous M@MN_(x)(M=Co,Fe,Ni)encapsulated in N-doped carbon layers supported with N-doped graphene sheets(denoted as M@MN_(x)@NC-NG)are synthesized by facile hydrothermal reaction and nitridation *** the nitriding process,metal ions in M(tzbc)_2(H_(2)O)_4(tzbc=4-(1H-1,2,4-triazol-1-yl)benzoic acid)complexes are reduced to crystalline M cores,accompanied by the formation of amorphous MN_(x)shells;the tzbc ligands are insitu carbonized to form outermost N-doped carbon(NC)layers that connect with inner MN_(x)via M-N-C motifs inherited from the complex precursors and inhibit the transition of MN_(x)from amorphous to crystalline *** Co@CoN_(x)@NC-NG catalyst exhibits excellent HER activity with small overpotentials of 45 and 64 mV at a cathode current density of 10 mA·cm^(-2)and low Tafel slopes of 40 and 85 mV·dec^(-1)in 0.5 mol·L^(-1)H_(2)SO_4 and1.0 mol·L^(-1)KOH electrolytes,*** Co@CoN_(x)@NC-NG retains 97%of the initial overpotential after 100,000 s in both acidic and alkaline *** outstanding HER performance originates from the crystalline-amorphous Co@CoN_(x)that redistributes electrons around the heterointerfaces,facilitating the conversion process of H^(+)/H_(2)O to hydrogen and thereby promoting HER *** outermost NC layers serve as the armor of Co@CoN_(x),and graphene nanosheets act as carriers of egg-like Co@CoN_(x)@NC and conduction paths for electron shuttles,ensuring stable and continuous electrocatalytic hydrogen production.

关键词： Hydrogen evolution reaction Electrocatalysts Iron group metals Heterojunction Crystalline-amorphous structure

Special Odd-Even Effect of Degree of Oligomerization on Properties of Cyclic Oligoesters

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Chinese Journal of Polymer Science 2015年第8期33卷 1069-1069,1070-1073页

作者： Jun Wu Tao-guang Qu Ling-feng Gao xiao-ming yang xiao-hong Li 屠迎锋 Xiu-lin Zhu Suzhou Key Laboratory of Macromolecular Design and Precision Synthesis Jiangsu Key Laboratory of Advanced Functional Polymer Design and ApplicationCollege of ChemistryChemical Engineering and Materials ScienceSoochow University

We demonstrate here seven pure cyclic samples, which belongs to two series of oligoesters, cyclic oligo（trimethylene terephthalate）s （COTTs） and cyclic oligo（butylene terephthalate）s （COBTs）, showing odd-even effect of degree of oligomerization （repeating units number） on properties. The pentamer of COTT and trimer of COBT show much lower melting temperature, and the trimer of COTT and trimer of COBT show significant lower refractive index, which can be ascribed to the low packing density of cyclic oligoesters with odd number of degree of oligomerization. Our results reveal the discrete property change as a function of cyclic size of oligomers, which can be used to design materials with special properties.

关键词： Cyclic polymer Oligomer Odd-even effect Refractive index.

Screening and Characterization of a Bioflocculant Produced by Aeromonas sp

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Biomedical and Environmental Sciences 2007年第4期20卷 274-278页

作者： JIN-JING LIU xiao-ming LI QI yang KAI HUANG GUANG-ming ZENG DE-XIANG LIAO WEN-FANG LONG College of Environmental Science and Engineering Hunan University Changsha 410082 Hunan China

To isolate the bioflocculant-producing bacteria from activated sludge and investigate the flocculating characteristics of the newly isolated bioflocculant. Methods Bacteria were screened from activated sludge samples to isolate bioflocculant-producing bacteria. Flocculating activity was used as a measure of the flocculating capability of the bioflocculant. Results A novel bioflocculant-producing bacterium was isolated, which was identified to belong to genus Aeromonas and named as Aeromonas sp. Nil. Flocculating activity increased in the presence of K, Na^＋, or Ca^2＋. The highest flocculating activities for kaolin suspension were obtained in acidic pH ranges, and optimum pHs for it were 3.0, 4.0, and 5.0 with 1 mmol/L K^＋, Ca^＋, and Na^＋ present, respectively. The highest flocculating activities for soil suspension were observed at pH 8.0. The bioflocculant had a good flocculating activity and could achieve a flocculating activity of 92.4% for kaolin suspension at a dosage of only 1 mg.L-1, and its activity in kaolin suspension was decreased by only 9.2% after heating at 100℃ for 60 min. Conclusion The bioflocculant produced by Aeromonas sp. Nil has strong flocculating activity and high stability, which affords high possibility of its practical use.

关键词： Aeromonas sp. Bioflocculant Biopolymer Flocculation