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Journal Articles

Recent progress of radiation physicochemical process (third part)

Kai, Takeshi; Yokoya, Akinari*; Fujii, Kentaro*; Watanabe, Ritsuko*

Hoshasen Kagaku (Internet), (106), p.21 - 29, 2018/11

It is thought to that the biological effects such as cell death or mutation are induced by complex DNA damage which are formed by several damage sites within a few nm. As the prediction of complex DNA damage at an electron track end, we report our outcomes. These results indicate that DNA damage sites comprising multiple nucleobase lesions with a single strand breaks can be formed by multiple collisions of the electrons within 1 nm. This multiple damage site cannot be processed by base excision repair enzymes. Pre-hydrated electrons can also be produced resulting in an additional base lesion over a few nm from the multi-damage site. This clustered damage site may be finally converted into a double strand break. These DSBs include another base lesion(s) at their termini that escape from the base excision process and which may result in biological effect. Our simulation is useful to reveal phenomena involved in radiation physico-chemistry as well as the DNA damage prediction.

Journal Articles

Microfabrication of fluoropolymers using ion beam irradiation

Kitamura, Akane; Kobayashi, Tomohiro*

Hoshasen Kagaku (Internet), (104), p.29 - 34, 2017/10

no abstracts in English

Journal Articles

Reactivity of an antioxidant, edaravone, with reactive oxygen species and its chemical repair properties against oxidative damage on DNA

Hata, Kuniki; Lin, M.*; Yokoya, Akinari*; Fujii, Kentaro*; Yamashita, Shinichi*; Muroya, Yusa*; Katsumura, Yosuke*

Hoshasen Kagaku (Internet), (103), p.29 - 34, 2017/04

Reactivity of edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one), which is known to show high antioxidative properties, with oxidative species, such as hydroxyl radical ($${}^{bullet}$$OH) and azide radical (N$$^{bullet}$$$$_{3}$$), was investigated by a pulse radiolysis experiment, and generation behavior of edaravone radicals produced through these reactions were observed. It was shown that OH-adducts are produced by the reaction with $${}^{bullet}$$OH in contrast to the other oxidative radicals, which react with edaravone by an electron transfer reaction. Chemical repair properties of edaravone against DNA lesions produced by reactions of DNA with oxidative species were also investigated by a pulse radiolysis experiment with deoxyguanosine monophosphate (dGMP) and a $$gamma$$-radiolysis experiment with plasmid DNA solutions. It was observed that edaravone reduced dGMP radicals just after produced in a dilute aqueous solution and inhibited some base lesions on plasmid DNA more effectively than single strand breaks. These results show that edaravone may protect living system from oxidative stress, such as radiation, by not only scavenging oxidative species but also reducing precursors of DNA leisons.

Journal Articles

Report on the stay in Norway as a secondee of OECD Halden Reactor Project

Hata, Kuniki

Hoshasen Kagaku (Internet), (103), P. 65, 2017/04

no abstracts in English

Journal Articles

Recent progress of radiation physicochemical process (first part)

Kai, Takeshi; Yokoya, Akinari; Fujii, Kentaro; Watanabe, Ritsuko

Hoshasen Kagaku (Internet), (101), p.3 - 11, 2016/04

Behavior analysis of low energy electrons in liquid water provides the fundamentals for successive radiation chemistry, and it makes analysis of DNA damage implication involved in the electrons possible. We have progressed theoretical studies for radiation physicochemical process of liquid water to clear the role of low-energy secondary electrons damage to DNA. The process has included many unknown factors for the DNA damage so far. Based on the results, we implied a newly formation process of unrepair DNA damage produced by the secondary electrons assumed that it was ejected from DNA by impact of a high energy electron. We report our outcomes separately in three manuscripts entitled "Recent progress of radiation physicochemical process (first, second, third parts)" to journal of radiation chemistry. In this first part, we outline recent status of studies for the DNA damage and the radiation physicochemical process, we also show calculation method of electron impact cross sections involved strongly in electron deceleration in liquid water in the topics of our outcomes. From the calculated results, we also report our prediction, which are different from previous one, for electron thermalization.

Journal Articles

Recent progress of radiation physicochemical process (second part)

Kai, Takeshi; Yokoya, Akinari*; Fujii, Kentaro*; Watanabe, Ritsuko*

Hoshasen Kagaku (Internet), (102), p.49 - 56, 2016/00

Behavior analysis of low energy electrons in liquid water provides the fundamentals for successive radiation chemistry, and it makes analysis of DNA damage implication involved in the electrons possible. We have progressed theoretical studies for radiation physicochemical process of water to clear the role of secondary electrons damage to DNA. The process has included many unknown factors for the DNA damage so far. We implied a newly formation process of unrepair DNA damage produced by the secondary electrons. We report our outcomes separately in three manuscripts entitled "Recent progress of radiation physicochemical process (first, second, third parts)". In this second part, we show calculated results of thermalization lengths and times of electrons in water to verify a dynamic Monte Carlo code developed in this study. From the calculated results, we also report our prediction, which are different from previous one, for thermalization and pre-hydration processes.

Journal Articles

Pulse beam formation technique for a cyclotron

Kurashima, Satoshi

Hoshasen Kagaku (Internet), (100), p.49 - 51, 2015/10

no abstracts in English

Journal Articles

Radiation processing in my research life

Tamada, Masao

Hoshasen Kagaku (Internet), (100), P. 16, 2015/10

Collection of a rare metal form hot spring water attracted medias and had a public response by reports of numerous newspapers and television programs in my 35 years' research and development of radiation processing technologies and its technology management. Collection experiments of the rare metal were carried out in Kusatsu Onsen, Gunma prefecture, where discharge of hot spring water is the largest in Japan. We were on standby 6 am there when morning live broadcast started from 8 am. The invention of emersion grafting solved the problems in the cost reduction of adsorbent production owing to its high grafting yield and led the way for technology transfer of filter for the removal of metal ions in ppb level from semiconductor cleaning liquid and adsorbent for radio-active cesium.

Journal Articles

Current status and future prospects of ion beam breeding

Hase, Yoshihiro

Hoshasen Kagaku (Internet), (100), p.86 - 88, 2015/10

no abstracts in English

Journal Articles

Degradation of 2-chlorophenol by $$gamma$$-ray irradiation in zeolite/water mixtures

Kumagai, Yuta

Hoshasen Kagaku (Internet), (99), p.53 - 56, 2015/04

Radiation-induced degradation of 2-chlorophenol (2-ClPh) in zeolite/water mixtures was studied in order to consider a possibility of adsorption on zeolites to improve efficiencies of irradiation treatments of water contaminated by organic compounds. The degradation of 2-ClPh by $$gamma$$-ray irradiation was investigated as a model compound. The degradation was evaluated by chloride ion (Cl$$^{-}$$) production. A high concentration of Cl$$^{-}$$ was observed after the irradiation of a mixture with a mordenite-type zeolite (NaMOR), whereas A-type and X-type zeolites showed no significant effect. Therefore, for the mixture with NaMOR, effects of pH of the solution and of the 2-ClPh concentration were examined. At pH 5.7, the excess production of Cl$$^{-}$$ was induced by the addition of NaMOR. Concurrently, adsorption of 2-ClPh on NaMOR was observed. When the mixture contained a higher concentration of 2-ClPh at pH 5.7, the Cl$$^{-}$$ production increased. The adsorption of 2-ClPh also increased with increasing concentration. The results suggest that organics adsorbed on zeolites are decomposed by irradiation effectively at high adsorption concentrations.

Journal Articles

Radiation processing using quantum beams

Tamada, Masao

Hoshasen Kagaku (Internet), (96), P. 1, 2013/09

Innovations in scientific technology are expected to revive the Japanese economy. Advantages of quantum beam technology are to be able to develop materials which have novel properties and superior functionality to those achieved by chemical methods. Such materials are favorable for technology transfer since they have higher potential than conventional products. This point is advantageous in quantum beam technology. Hence, it is extremely important that research and development of both new technology of quantum beams and new seeds aiming at industrial applications.

Journal Articles

R&D of removal technology of radioactive contaminants from the environment by using polymer absorbents

Ito, Hisayoshi; Seko, Noriaki; Kuroki, Ryota; Yaita, Tsuyoshi; Naganawa, Hirochika; Nakayama, Shinichi

Hoshasen Kagaku (Internet), (93), p.31 - 36, 2012/03

For removing radioactive contaminants from the environment due to the nuclear plant accident, we have synthesized highly efficient cesium absorbents by introducing molybdophosphoric acid groups into polyethylene matrix with radiation grafting. Cesium absorbents based on protein or crown ether materials have been newly developed. We have also established immobilization-collection technology of cesium-adsorbed surface soil by using a mixture of polyion and bentonitic clay material. The effectiveness of these materials has been demonstrated through the field examination in Fukushima.

Journal Articles

Radiation chemistry of high temperature and supercritical water

Lin, M.; Katsumura, Yosuke*; Muroya, Yusa*

Hoshasen Kagaku (Internet), (93), p.3 - 13, 2012/03

The state-of-the-art in the field of water radiolysis at elevated temperatures and supercritical water are reviewed, with the emphasis on the temperature and density effects on the radiolytic yields of water decomposition products, the reaction rate constants and the spectral properties of hydrated electron. The latest studies on supercritical water by picosecond pulse radiolysis as well as some main results about pulse radiolysis of alcohols at elevated temperatures are also introduced.

Journal Articles

Introduction to T$$_{rm E}$$X, 2; How to use it

Oka, Toshitaka; Ito, Kenji*

Hoshasen Kagaku (Internet), (93), p.57 - 61, 2012/03

no abstracts in English

Journal Articles

Foundations of radiation chemistry; Early processes of radiolysis by V. M. Byakov and S. V. Stepanov, 2

Kobayashi, Yoshinori*; Oka, Toshitaka

Hoshasen Kagaku (Internet), (93), p.47 - 56, 2012/03

no abstracts in English

Journal Articles

Studies on radiation effects in decomtamination of radioactive water by using zeolites as absorbents for radioactive nuclides

Nagaishi, Ryuji

Hoshasen Kagaku (Internet), (92), p.15 - 21, 2011/09

AA2011-0467.pdf:0.57MB

Radioactive water has been emitted following incidents at the Fukushima Dai-ichi Nuclear Power Station, and needed to be quickly decontaminated by the adsorption and/or the coagulation sedimentation of radioactive nuclides, where hydrogen molecules are produced by water radiolysis. The decontamination process with zeolites as absorbents of radioactive cesium was assumed, the observed yields of hydrogen production were determined in mixtures of seawater and zeolite, and then the production rates were estimated for the safety operation of process before the operation started.

Journal Articles

Foundations of radiation chemistry; Early processes of radiolysis by V. M. Byakov and S. V. Stepanov, 1

Kobayashi, Yoshinori*; Oka, Toshitaka

Hoshasen Kagaku (Internet), (92), p.39 - 49, 2011/09

Contents of the lecture note by Prof. V. M. Byakov and Dr. S. V. Stepanov (Institute of Theoretical and Experimental Physics, Russia) are described in a series of articles. The first article concerns basic concepts, classification and sources of ionizing radiations.

Journal Articles

Introduction to TeX, 1; How to install it

Oka, Toshitaka; Ito, Kenji*

Hoshasen Kagaku (Internet), (92), p.51 - 53, 2011/09

no abstracts in English

Journal Articles

Experiences in bio-chemistry laboratories

Fujii, Kentaro

Hoshasen Kagaku (Internet), (92), p.65 - 66, 2011/09

no abstracts in English

Journal Articles

Application of ionic liquid as a reaction field of radiation chemistry

Kimura, Atsushi

Hoshasen Kagaku (Internet), (91), p.28 - 31, 2011/03

no abstracts in English

119 (Records 1-20 displayed on this page)