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REACTION MECHANISM OF BENZOPHENONE-PHOTOINITIATED CROSSLINKING OF POLYETHYLENE

Chinese Journal of Polymer science 2002年第4期20卷 291-307页

作者： Bao-jun Qu State Key Laboratory of Fire science and Department of Polymer science and engineering University of science and Technology of china Hefei 230026 china Univ Sci & Technol china State Key Lab Fire Sci Hefei 230026 Peoples R China Univ Sci & Technol china Dept Polymer Sci & Engn Hefei 230026 Peoples R China

The radical intermediates, the crosslink microstructures, and the reaction mechanism of benzophenone (BP)-photoinitiated crosslinking of low-density polyethylene (LDPE) and model compounds (MD) have been reviewed in detail. The spin-trapping electron spin resonance (ESR) spectra obtained from the LDPE/BP systems with spin-trap agents show that two kinds of polymer radical intermediates are mainly formed: tertiary carbon and secondary carbon radicals. The spin-trapping ESR studies of MD/BP systems give further evidence that photocrosslinking reactions of PE predominantly take place a sites of tertiary carbon, secondary carbon, and especially allylic carbon when available. The high resolution C-13-NMR spectra obtained from LDPE and MD systems show that the crosslink microstructures have H- and Y-type links and that their concentrations are of the same order. The fluorescence, ESR, C-13 and H-1-NMR spectra from the PE and MD systems demonstrate that the main photoreduction product of BP (PPB) is benzpinacol formed by the recombination of two diphenylhydroxymethyl (K-.) radical intermediates. Two new PPB products: an isomer of benzpinacol with quinoid structure, 1-phenylhydroxymethylene-4-diphenylhydroxymethyl-2,5-cyclobexadiene and three kinds of alpha-alkyl-benzhydrols have been detected and identified. These results provide new experimental evidence for elucidating the reaction mechanism in the BP-photoinitiated crosslinking of polyethylene.

关键词： photocrosslinking mechanism polymer radical intermediates crosslink microstructures photolytic products of benzophenone polyethylene model compound

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Mesh theory of angle modified dual tori double-enveloping toroidal worm drive

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science china(Technological sciences) 2010年第7期53卷 1913-1927页

作者： ZHAO YaPing1, SU DaiZhong2, ZHANG Zhao1, WEI WenJun3 & DONG XueZhu3 1 college of Machinery and Automation, Wuhan University of science and Technology, Wuhan 430081, china 2 Advanced Design and Manufacturing engineering Center, Nottingham Trent University, Nottingham NG1 4BU, UK 3 college of engineering, china Agricultural University, Beijing 100083, china 1. college of Machinery and Automation Wuhan University of Science and Technology Wuhan 430081 China2. Advanced Design and Manufacturing Engineering Center Nottingham Trent University Nottingham NG1 4BU UK3. College of Engineering China Agricultural University Beijing 100083 China

In this paper, the meshing theory of the angle modified hourglass worm drive is enriched and developed. The ordinary condition of the angle modification is derived and the physical significance of the modification is interpreted. A normal section methodology is proposed for meshing analysis, which can be used to compute the normal distance near a singular meshing point of a conjugate surface couple. By means of the method and after analyzing the normal transversals, it is specified that the worm helicoid, the nominal former contact zone and the new contact zone intersect each other along the locus of singular points of the instantaneous contact lines of an angle-modified worm pair. As a result, it is explained clearly that those three osculate each other but the osculations are different in degree. Moreover, the mechanism of removing the twice-contacted zone from the worm gear tooth surface is clarified and the reason of shortening the worm working length is also elucidated. With the help of the theory described in the present paper and the thorough and systematic research on the relevant meshing characteristics, the angle modified dual tori double-enveloping toroidal worm drive has been shown to be an excellent new-fashioned hourglass worm set.

关键词： hourglass worm angle modification double-enveloping osculation normal transversal

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Sensitization and Intra-molecular Energy Transfer of Eu^(3+) by Tb^(3+) in Eu-Tb Binuclear Complexes/PMMA

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Journal of Wuhan University of Technology(Materials science) 2011年第3期26卷 398-402页

作者：韩晶 college of Mechatronic engineering North University of China

A series of Eu0.5Tb0.5（TTA）3Phen/PMMA （TTA=thenoyltrifluoroacetone,Phen=phenanthroline） and Eu0.5Tb0.5（TTA）3Dipy/PMMA （Dipy=2,2’-dipyridyl） were prepared by in-situ *** structures of the composites were characterized by IR spectra and electron *** properties were investigated by UV-Vis spectra and fluorescence ***,the energy transfer models were set *** results indicated that polymer parts were attached with the rare-earth molecular parts in the composite luminescent ***0.5Tb0.5（TTA）3Phen/PMMA and Eu0.5Tb0.5（TTA）3Dipy/PMMA emitted mostly characteristic fluorescence of europium ion and intense red fluorescence with peak wavelength at 611.8 nm and bandwidth of 10.4 nm under UV excitation at 365 *** intensity of Eu0.5Tb0.5（TTA）3Phen/PMMA was found to be influenced with the content of *** fluorescence emission of europium ions was greatly sensitized by terbium ions and the enhancement of red emission was most likely due to the energy transfer enhancement from Tb3＋ to Eu3＋.

关键词： sensitization energy transfer rare-earth polymer in-situ polymerization

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Numerical Simulation of Solidification Microstructure and Effects of Phase-field Parameters on Grain Growth Morphologies

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Journal of Materials science & Technology 2005年第6期21卷 921-924页

作者： Jingfeng LIU+, Ruixiang LIU and Liliang CHEN Research Studio of Solidification Simulation, college of Materials science and engineering, Huazhong University of science and Technology, Wuhan 430074, china Research Studio of Solidification Simulation College of Materials Science and Engineering Huazhong University of Science and Technology Wuhan 430074 China

By a simple phase field model, a series of numerical simulations of solidification microstructure was performed to show a rich variety of dendritic patterns. At the same time, the relation between the morphology of grain growth and some parameters including the strength of anisotropy, dimensionless latent heat and the size of initial solid zone was studied. It is for the first time that patterns of grain growth were associated with the size of initial solid zone, which is an interesting issue. The possible reason for this may be that variation in the size of initial solid zone may bring about fluctuation of the interface energy, making the interface unstable.

关键词： Phase-field model Dendritic pattern Simulation

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Dark respiration in the light and in darkness of three marine macroalgal species grown under ambient and elevated CO_2 concentrations

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Acta Oceanologica Sinica 2011年第1期30卷 106-112页

作者： ZOU Dinghui GAO Kunshan XIA Jianrong college of Environmental science and engineering South China University of Technology Guangzhou 510006 China The Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters Ministry of Education Guangzhou 510006 China State Key Laboratory of Marine Environmental science Xiamen University Xiamen 361005 China college of Environmental science and engineering Guangzhou University Guangzhou 510006 China

Dark respiration （non-photorespiratory mitochondrial respiration）, which occurs both in the light and in darkness, is vital for growth and survival of algae and plays a critical role in modulating the carbon balance of them. In the present study, we have investigated dark respiration in the light （RL） and in darkness （RD） in three marine macroalgal species, Hizikia fusiformis （phaeophyta）, Gracilaria lemaneiformis （Rhodophyta） and Ulva lactuca （Chlorophyta）, cultured at 20 ℃ using aeration with two CO2 conditions： current ambient （CO2 concentration about 380 μl/L） and elevated CO2 （approximately 720 μl/L） air. RL was estimated by using the Kok method, whereas RD was determined as the rate of O2 influx at zero light. The results showed that both RL and RD were unchanged for the elevated CO2-grown algae relative to ambient CO2 concentration for all the algal species tested. However, RL was significantly lower than RD across all the algal species and growth CO2 treatments, demonstrating that daytime respiration was partly depressed by the light. The percentage of inhibition of respiration by light was similar between ambient and elevated CO2- grown algae. The ratio of respiration to photosynthesis, which tended to decrease when estimated using RL instead of RD, was not altered for the elevated relative to ambient CO2 concentration. The results suggest that RL, rather than RD, is a more accurate estimate of nonphotorespiratory carbon loss in marine macroalgae during the daytime. It would not be anticipated that elevated atmospheric CO2 would exert a substantial influence on respiratory flux either in the light or in darkness in these particular marine macroalgal species.

关键词： marine macroalgae respiration CO2 carbon balance

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Immunohistochemical localization of Ca^(2+)/calmodulin-dependent kinase in tobacco

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Chinese science Bulletin 2001年第3期46卷 230-233页

作者： YANG Wannian, LIANG Shuping & LU YingtangCenter of Developmental Biology, college of life science, Wuhan University, Wuhan 430072, china Center of Developmental Biology College of Life Science Wuhan University Wuhan China

The existence of Ca2+/calmodulin-dependent kinase (CaM kinase, CaMK) in tobacco is verified immuno-logically and its distribution in different tissues of tobacco is studied. It has been demonstrated that CaMK is mainly distributed in early developing anthers, developing ovules and embryos, lateral root primordium, apical meristem and leaf primordium of buds and mesophyll cells and developing vascular bundles of leaves. There is enormous CaM kinase distributed in leaf epidermis fair cells and guard cells of stomas too. Little kinase is found in mature stem or root cells. The distribution properties of CaM kinase in tobacco are consistent with those of CaM, suggesting that there exists the Ca2+ signal transduction pathway mediated by CaM kinase in tobacco and it plays an important role in the plant growth and development.

关键词： CaM kinase immunohistochemical localization tobacco anthers.

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Synthesis,characterization and photodynamic activity of ethanolamino-substituted hypocrellin B(EAHB2)

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生物物理学报 2009年第S1期25卷 441-442页

作者： Zhixiang Zhou, Lina Zhang,Ping Ai,Hongtao Ma college of life science and Bio-engineering, Beijing University of Technology, Beijing, 100124, china

The limitations of currently used clinical phototherapeutic agent, Photofrin, have prompted a search for more ideal photodynamic sensitizer. The hypocrellins, have been paid the

关键词： Photodynamic therapy(PDT) ethanolamino-substituted hypocrellin B(EAHB2) MGC-803 cell MCF-7 cells cell cycle arrest apoptosis

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Role of Friction in Cold Ring Rolling

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Journal of Materials science & Technology 2005年第6期21卷 914-920页

作者： He YANG+, Lianggang GUO and Mei ZHAN college of Materials science and engineering, Northwestern Polytechnical University, Xi’an 710072, china college of Materials science and engineering Northwestern Polytechnical University Xi'an 710072 China

Cold ring rolling is an advanced but complex metal forming process under coupled effects with multi-factors, such as geometry sizes of rolls and ring blank, material, forming process parameters and friction, etc. Among these factors, friction between rolls and ring blank plays an important role in keeping the stable forming of cold ring rolling. An analytical method was firstly presented for proximately determining the critical friction coefficient of stable forming and then a method was proposed to determine the critical friction coefficient by combining analytical method with numerical simulation. And the influence of friction coefficient on the quality of end-plane and side spread of ring,rolling force, rolling moment and metal flow characteristic in the cold ring rolling process have been explored using the three dimensional （3D） numerical simulation based on the elastic-plastic dynamic finite element method （FEM） under the ABAQUS software environment, and the results show that increasing the friction on the contact surfaces between rolls and ring blank is useful not only for improving the stability of cold ring rolling but also for improving the geometry and dimension precision of deformed ring.

关键词： Cold ring rolling Friction Elastic-plastic dynamic explicit FEM ABAQUS

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Cu(Ⅱ) Potentiation of Alzheimer Aβ1-40 Cytotoxicity and Transition on its Secondary Structure

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Acta Biochimica et Biophysica Sinica 2006年第11期38卷 765-772页

作者： Xue-Ling DAI~1 Ya-Xuan SUN~2 Zhao-Feng JIANG~2* 1 college of life science,Capital Normal University,Beijing 100037,china 2 college of Applied sciences and Humanities,Beijing Union University,Beijing 100083,china college of life science Capital Normal UniversityBeijing 100037 China college of Applied sciences and Humanities Beijing Union UniversityBeijing 100083 China

Mounting evidence has shown that dyshomeostasis of the redox-active biometals such as Cuand Fe can lead to oxidative stress,which plays a key role in the neuropathology of Alzheimer's disease（AD）.Here we demonstrate that with the formation of Cu（Ⅱ）·Aβ1-40 complexes,copper markedly potentiatesthe neurotoxicity exhibited by β-amyloid peptide （Aβ）.A greater amount of hydrogen peroxide was releasedwhen Cu（Ⅱ）·Aβ1-40 complexes was added to the xanthine oxidase/xanthine system detected by potassiumiodide *** bound to Aβ1-40 was observed by electron paramagnetic resonance（EPR） *** dichroism （CD） studies indicated that copper chelation could cause a structuraltransition of Aβ.The addition of copper to Aβ introduced an increase on β-sheet as well as α-helix,whichmay be responsible for the aggregation of Aβ.We hypothesized that Aβ aggregation induced by copper maybe responsible for local injury in *** interaction between Cu2+and Aβ also provides a possible mechanismfor the enrichment of metal ions in amyloid plaques in the AD brain.

关键词： Alzheimer’s disease Cu(Ⅱ)·Aβ1-40 complex neuron injury Aβ secondary structure

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Synthesis of a novel benzoxazine containing benzoxazole structure

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Chinese Chemical Letters 2010年第5期21卷 558-562页

作者： Po Yang,Yi Gu State Key Laboratory of Polymer Materials engineering,college of Polymer science and engineering, Sichuan University,Chengdu 610065,china [a] State Key Laboratory of Polymer Materials engineering College of Polymer Science engineering Sichuan University Chengdu 610065 China

A high-purity benzoxazine（Boz-BOA） containing benzoxazole structure was successfully synthesized by three-step synthetic method using 2-（4-aminophenyl）-1H-benzoxazole-5-amine（BOA） and *** structure of Boz-BOA was confirmed by FTIR and;H NMR *** DSC was utilized to probe the curing behavior of Boz-BOA and exhibited a narrow melting peak and curing exothermic peak.

关键词： Benzoxazine Benzoxazole Synthesis Characterization

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