| Project/Area Number |
11308019
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Nuclear engineering
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| Research Institution | Osaka University |
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Principal Investigator |
TAGAWA Seiichi Osaka University, the Institute of Scientific and Industrial Research, Professor, 産業科学研究所, 教授 (80011203)
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| Co-Investigator(Kenkyū-buntansha) |
KOBAYASHI Kazuo Osaka University, the Institute of Scientific and Industrial Research, Research associate, 産業科学研究所, 助手 (30116032)
OKUDA Shuichi Osaka University, the Institute of Scientific and Industrial Research, Associate Professor, 産業科学研究所, 助教授 (00142175)
YOSHIDA Yoichi Osaka University, the Institute of Scientific and Industrial Research, Associate Professor, 産業科学研究所, 助教授 (50210729)
KOZAWA Takahiro Osaka University, the Institute of Scientific and Industrial Research, Research associate, 産業科学研究所, 助手 (20251374)
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| Project Period (FY) |
1999 – 2001
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥39,100,000 (Direct Cost: ¥37,000,000、Indirect Cost: ¥2,100,000)
Fiscal Year 2001: ¥9,100,000 (Direct Cost: ¥7,000,000、Indirect Cost: ¥2,100,000)
Fiscal Year 2000: ¥7,000,000 (Direct Cost: ¥7,000,000)
Fiscal Year 1999: ¥23,000,000 (Direct Cost: ¥23,000,000)
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| Keywords | pulse radiolysis / femtosecond / DNA / water / hydrated electron / guanine / coherent radiation / primary processes of radiation chemistry / 溶媒和電子 / コヒーレント放射 / 電子ビーム / レーザー / 生体 / 初期過程 |
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| Research Abstract |
To investigate the primary processes of radiation chemistry in aqueous solution, a high time-resolution pulse radiolysis system was developed. The system consists of a femtosecond electron linac, a femtosecond laser, a jitter compensation system and a high resolution detection system for optical absorption spectroscopy. The jitter compensation system was designed to avoid the degradation of time resolution caused by synchronization jitter between the laser and the accelerator. In this method, the time interval between a laser pulse and an electron pulse was measured at every shot with a femtosecond streak camera with the time resolution of 185 fs. The degradation of S/N ratio caused by the vibration of optical elements was reduced with the double pulse method. The time resolution was estimated with water sample whose refractive index is 1.33. The time resolution (10-90% rise time) were 2.0 ps in the use of 2.0 mm cell and 800 fs in the use of 0.5 mm cell. Far-infrared coherent radiation was applied to the spectroscopy of water sample. The refractive indices and absorption coefficients of water and their temperature dependency were obtained in the far-infrared wavelength region. To make clear the radiation damage mechanism of DNA, one-electron oxidized forms of double stranded DNA were investigated by the technique of pulse radiolysis. The radical cation of quanosine, resulted in the reaction of SO_4^-, deprotonated to form the radical with a rate constant of 1.7 x 10^7 s^<-1>. In contrast, the deprotection process of the oxidized guanine moiety in E.coli DNA (3.5 x 106 s^<-1>) is slower than that of guanosine. We further analyzed the deprotonation process in different oligonucleotide sequence after generation of the one-electron oxidized form in double stranded oligonucleotides. The absorbance changes followed at 625 nm were found to consist with the faster and slower phase.
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