最新刊期
      期 4 ， 2002
      • LI Rongqun,YAO Side,ZHANG Cong,LI Wei,HAN Zhenhui,LIN Weizhen
        Vol. 20, Issue 4, Pages: 225-230(2002)
        摘要：The influences of processing conditions on polyethylene/carbon black composites with two types of PE are studies in this paper, including mixing temperature, mixing time, additives, heating treatment and irradiation. And the optimized process conditions are obtained. It is found that the composites based on different PE matrices exhibit different properties, which is attributed to the different viscosity of the matrices. PE20/CB composites show excellent mixing properties, low room —temperature resistivity and considerable PTC effect when containing 18%—26% content of CB, while PE2/CB composites are much better in stability and the elimination of NTC effect. It is suggested that the combination of different matrices in one composite may be a convenient method to fabricate more superior polymeric PTC materials.  
        关键词：Polymer composite;PTC effect;Processing conditions   
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        发布时间：2023-05-04
      • ZHAO Yaping,QIAN Suping,YU Wenli,YAO Side,WANG Wenfeng,Wang Dapu
        Vol. 20, Issue 4, Pages: 231-234(2002)
        摘要：The antioxidant activity of natural α-tocopherol (α-TH) is investigated towards trichloromethylperoxyl free radical (CCl3O2·) by means of a pulse radiolysis technique. CCl3O2· was generated from a pulsed solution containing 2-propanol (2M) and CCl4(10-2M) in the presence of air. The observed spectrum showed two transient absorption peaks at 340nm and 430nm, which were assigned to α-TH radical. The rate constant was calculated to be 2.65×104 M-1s-1, which suggested a quick interaction between α-TH and CCl3O2·. The reaction between α-TH and CCl3O2· may go on via hydrogen transfer mechanism.  
        关键词：α-tocopherol;Trichloromethyl peroxyl radical;Pulse radiolysis;Rate constant   
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        发布时间：2023-05-04
      • PAN Jingxi,LIN Weizhen,HAN Zhenhui,LI Rongqun,WANG Wenfeng,YAO Side,LIN Nianyun,ZHU Dayuan
        Vol. 20, Issue 4, Pages: 235-240(2002)
        摘要：By using of laser flash photolysis and pulse radiolysis techniques, a study of photophysics of ADE, which is a kind of model compound of actinomycin D, was carried out in varied solutions. The transient species generated by photolysis were identified, and the self—quenching rate constant, extinction coefficient and quantum yield of the triplet state ADE were determined. These results will be helpful for understanding the photodynamic processes of ADE and actinomycin D.  
        关键词：Actinomycin D;Laser flash photolysis;Excited triplet state;Photophysics   
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        发布时间：2023-05-04
      • ZHAO Hongwei,DOU Daying,MIAO Jinling,YAO Side,JIANG Zhiqin,ZHAO Chunlei
        Vol. 20, Issue 4, Pages: 241-245(2002)
        摘要：The absorption spectra of N-4-desmethylwyosine (dYt), a derivative of the tricyclic modified nucleoside wyosine, in aqueous solutions were studied by time-resolved laser photolysis. The oxidizing radical SO4·- was used to produce dYt radical cation. The mechanism of dYt monophotonic ionization was suggested. Distinct triplet was not observed in this work. The quantum yield of formation of hydrated electrons (Φe-) was determined to be 0.04 at room temperature in neutral aqueous solution by using KI solution as a reference.  
        关键词：Derivative of tricyclic modified nucleoside;Monophotonic ionization;Radical;Laser photolysis;Transient absorption spectrum   
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        发布时间：2023-05-04
      • SONG Chunlei,ZHANG Wende,LUO Yunxia,FUMIO Yoshii
        Vol. 20, Issue 4, Pages: 246-250(2002)
        摘要：A new biodegradable polymer coating fibre cloth composites has been achieved by γ rays irradiation in the present study. The mechanical properties (Bending Strength and Bending Modulus ) of poly (ε-caprolactone), PCL/carbon or glass fibre composites were investigated. γ rays irradiation improved the mechanical properties of composites due to the formation of gel by crosslinking. PCL/glass fibre cloth reinforced composites by irradiation at supercooled state in vacuum with increasing dose up to 270kGy, the composites gave higher bending strength of 1.5 times and bending modulus of 1.35 times compared with unirradiated composites. PCL in composites degraded by microorganisms in soil burial test and enzymatic degradation test. The degradation led to a weight loss. During enzymatic degradation test, after 23h immersion there were a 100% PCL weight loss for the unirradiated composite and 54% PCL weight loss for the irradiated composite. Weight loss of PCL gradually increases with increasing burial time. After 12 weeks in burial time, weight loss of 30% PCL was achieved for the uncrosslinked composite, while, for crosslinked composite (gel content 69%) , weight loss of 20% was achieved.  
        关键词：Poly (ε-caprolactone) (PCL);Glass fibre cloth;Carbon fibre cloth;Irradiation crosslinking;Mechanical properties;Biodegradation   
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        发布时间：2023-05-04
      • AI Biankai,WEI Jie
        Vol. 20, Issue 4, Pages: 251-254(2002)
        摘要：Polyethylene glycol diacrylate (PEGDA), which contained acrylic end - groups, was prepared for solid polymer electrolytes(SPE) with a solid acid as catalyst. A novel type of SPE was obtained by mixing PEGDA with photoinitiator, LiClO4, and plasticizer, and then being irradiated by UV light. The UV-curing, conducting and mechanical performances, depending on the type and the contend of plasticizer, were primarily discussed. The conclusion showed: plasticizing was an efficient method of improving the conductivity of UV-curable solid polymer electrolytes, and the conductivity of this kind of electrolytes was up to about 10-4S/cm when the mechanical performance of it was satisfying.  
        关键词：Plasticizing;UV- curing;Polymer solid electrolytes;Conductivity   
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        发布时间：2023-05-04
      • SUN Fang,LIU Ji,HUANG Yuli
        Vol. 20, Issue 4, Pages: 255-259(2002)
        摘要：The influences of different free radical photoinitiators and their contents on the photosensitivity of cycloaliphyatic epoxy polysiloxane(CEPS) photopolymerization systems initiated by diaryliodonium salts SR-1012 were investigated. The results shown that free radical photoinitiators could significantly amplify the photosensitivity of CEPS initiated by SR-1012. The value of optimized photosensitivity dropped to 121mJ/cm2 using Irgacure 184 as a sensitizer. It was also found that the suitable ratio of free radical photoinitiator and SR-1012 is not more than 1:2(wt).  
        关键词：Cationic polymerization;UV-curing;Sensitization;Polysiloxane   
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        发布时间：2023-05-04
      • WANG Chunyan,ZHANG Wei,CHEN Deqing,I. Hayata,M. Minamihisamatsu,H. Morishima,YUAN Yongling,WEI Luxin,Sugahara T
        Vol. 20, Issue 4, Pages: 260-264(2002)
        摘要：Chromosome translocations were analyzed by chromosome painting techniques using No. 12 and 4 whole chromosome painting probes to examine the effect of high-level natural radiation on the frequencies of chromosome translocations in human peripheral lymphocytes. The subjects were 5 children and 13 old men from the high background radiation area and 6 children and11old men from the control area. Children had lesser translocations and smaller variation compared with the old men. The frequency of translocations among the old subjects varied widely from person to person. No difference of the frequency of chromosome translocations between high background radiation area and control area. No effect of high-level natural background radiation on the frequencies of stable chromosome translocation was detected.  
        关键词：High background radiation;Human lymphocyte;Chromosome painting;Chromosome translocation;Health effect of radiation   
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        发布时间：2023-05-04
      • DING Yunsheng,ZHANG Zhicheng,HU Keliang,SHI Tiejun
        Vol. 20, Issue 4, Pages: 265-270(2002)
        摘要：A study on the oxidation of high density polyethylene (HDPE) by γ ray irradiation in oxygen atmosphere has been made. The influence of irradiated time on the oxidation has been investigated with the help of Fourier Transform Infrared– Photoacoustics Spectroscopy (FTIR-PAS) . Results of FTIR-PAS show after irradiation groups like -C=O, -O-C-O-, O=C-O- were introduced into the HDPE. Although the γ ray has powerful penetrability, the oxidation mainly takes place on the surface of HDPE. After 4h irradiation in oxygen (dose rate 66Gy/min. ) , -C=O is the main group which was introduced into the surface of HDPE. Lengthening the irradiation process makes the pre-produced oxidized section in HDPE surface continue their reactions to yield some oxidation products with the structures of -O-C-O-, O=C-O- and so on. FTIR shows there are reactions or week interaction like hydrogen bond between the irradiated HDPE and PA6 in the binary blends, this is helpful to increase the compatibility of the phase of HDPE and polyamide-6(PA6) in the blend. Scanning Electron Microscope (SEM) result shows that the interface between HDPE matrix and PA6 domains is much clear and smoother in 0γHDPE/PA6 blends than in 4γHDPE/PA6 and 7γHDPE/PA6 blends. These suggested the miscibility of PA6 and HDPE was improved after HDPE irradiating in oxygen by γ ray radiation.  
        关键词：Photoacoustics spectroscopy;Oxidation by γray irradiation;High density polyethylene;Compatibility   
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        发布时间：2023-05-04
      • LIU Xiaodong,LIU Shuzheng,MA Shumei,LIU Yang
        Vol. 20, Issue 4, Pages: 271-274(2002)
        摘要：To observe the effects of LDR on the p38 MAPK expression and the secretion of IL-12 in J774A.1 cell line, we used ELISA and flow cytometry to examine the changes in these two specialities. Results showed that IL-12p70 in J774A. 1increased 2-8h after 75mGy X irradiation, and consistently, p38 MAPK expression increased at the 2nd h after exposure. Both of these increases showed statistic significance. Conclusions were drawn that LDR might stimulate IL-12 expression , and p38 MAPKmight play some role in the activation of IL-12, which would provide theoretic basis for the hormesis effect of LDR.  
        关键词：Low dose radiation;Radiation hormesis;IL-12;p38MAPK   
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        发布时间：2023-05-04
      • CONG Yuwen,CHEN Jiapei,SHAO Yuan,WANG Jinhui,YUAN Xiaoling,ZHAO Zhenhu,LIU Xiaolan
        Vol. 20, Issue 4, Pages: 275-280(2002)
        摘要：To deepen the cognition of the molecular mechanism of radiation injury of hematopoietic cells. Using receptor ligand binding assay the changes of the characteristic of G—CSF receptors of NFS-60 cells were observed after irradiation. The Kd and Bmax of G-CSF receptor of NFS-60 cells were elevated with the radiation dose increasing in 30min after irradiation, and the Kd was increased more markedly. 30min after irradiation , the Kd and Bmax recovered for1Gy irradiated cells; but even 24h after irradiation, the Kd(s) and Bmax(s) for 3Gy and 5Gy-irradiated cells did not decrease markedly and the Bmax(s) were even larger than those 30h after irradiation. The increase of Kd of G-CSF receptor after irradiation might be one of the reasons for radiation injury of hematopoietic cells.  
        关键词：Radiation;G-CSF;Receptor;Hematopoietic cells   
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        发布时间：2023-05-04
      • YANG Yepeng,CHEN Guanying,GUAN Zengwei,ZHOU Mei,SHEN Qinjian,SHEN Lei
        Vol. 20, Issue 4, Pages: 281-283(2002)
        摘要：To investigate the effects of ionizing radiation on cell cycle progress of tumor cell lines, the human breast cancer MCF-7 cell line cultured in vitro was exposed to 60Co γ rays and the alterations in cell cycle progress after irradiation were measured by flow cytometry.The results indicated that the MCF-7 cells showed a transient S arrest continuing for about 6h and an obvious G2 arrest continuing for about 63h after irradiation with 5.0Gy γ rays. S and G2 arrest culminated at 9h and 18h respectively after irradiation and the peak values of S and G2 arrest reached respectively 1.6 times and 6.2 times as many as normal value. The dose-effect curve examined 9h after irradiation was quite different from that examined 18h after irradiation. Both of the S arrest at 9h after irradiation and the G2 arrest at 18h after irradiation presented significant relationship with irradiation dose.  
        关键词：Ionizing radiation;MCF-7 cell line;Cell cycle   
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        发布时间：2023-05-04
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