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Journal Articles

Time-dependence of differential G-values of OH radicals in water under Ne ion radiolysis

Taguchi, Mitsumasa; Kojima, Takuji

JAEA-Review 2005-001, TIARA Annual Report 2004, p.181 - 182, 2006/01

The yields of OH radicals in water containing phenol have been investigated for several ten MeV/n C ion and Ne ion having the same LET value, as a function of the residual ion energy at the specific depth in water. In this study, beside such energy dependence, the dependence of reaction time of OH radical yield was examined by changing the concentration of phenol as solute. The defferential G'-values of OH radicals, those G-values per kinetic energy of ions increase with specific energy of Ne ions. The G'-value just after irradiation(1.5ns) is relatively high but become lower with reaction time to be the value (2.7) obtained for $$^{60}$$Co $$gamma$$-rays. It suggests the diffusion behavior of OH radicals locally induced in water.

Journal Articles

Chain terminations in the decomposition reactions of chloroethylenes in air through the deposition of alkylperoxy radicals on the wall of an irradiation vessel

Hakoda, Teruyuki; Kojima, Takuji

Radiation Physics and Chemistry, 74(5), p.302 - 309, 2005/12

 Times Cited Count:0 Percentile:0.01(Chemistry, Physical)

no abstracts in English

Journal Articles

Gas purification technology using electron beams

Kojima, Takuji

Shinku, 47(11), p.789 - 795, 2004/11

When flue gas/off gas is irradiated by EB, many free radicals such as OH and active oxygen atom are formed from major components of air: namely nitrogen, oxygen, water and carbon dioxide ecules. The similer reaction can be achieved using UV light and plasma-discharging, but ionizing radiations produce such free radicals at higher density. Such radiation-induced radicals react efficiently with air pollutants, SOx and NOx in coal/oil combustion flue gas at thermal power plants, dioxins in waste incineration flue gas and volatile organic compounds (VOC) even in very low concentration and decompose them into non-toxic substances or change them to removable substances. R & D on EB treatment of flue gas/off gas done in JAERI on the basis of this principle process, as an example, is described in the present paper.

Journal Articles

On the radiation-induced polyaddition of bisperfluoroisopropenyl terephthalate with 1,4-dioxane

Enomoto, Kazuyuki*; Narita, Tadashi*; Maekawa, Yasunari; Yoshida, Masaru; Hamana, Hiroshi*

Journal of Fluorine Chemistry, 125(7), p.1153 - 1158, 2004/07

 Times Cited Count:3 Percentile:11.6(Chemistry, Inorganic & Nuclear)

Radical polyaddition of bis($$alpha$$-trifluoromethyl-$$beta$$,$$beta$$-difluorovinyl) terephthalate (BFP) with 1,4-dioxane (DOX) afforded higher molecular weight polymers under $$gamma$$-rays compared to those yielded by benzoyl peroxide initiation. More detailed study on the radiation-induced polyaddition of BFP with DOX and optimization of the reaction conditions were carried out. It was necessary to irradiate with doses of 2000, 1500, and 750 kGy, to obtain quantitative conversion of BFP at the feed molar ratio DOX/BFP of 8.0, 16, and 32, respectively. Step-growth polymerization mechanism was suggested by the measurements of molecular weights of the polymers obtained with several irradiation doses. It was concluded that the molecular weight of the polymer could be controlled by the feed molar ratio of DOX/BFP and irradiation doses. The reaction between polymers might take place after the quantitative conversion of BFP. Radiation-induced radical polyaddition mechanism of BFP with DOX was proposed.

Journal Articles

Production mechanism of DNA bases radical induced by inner-shell excitation

Yokoya, Akinari

Hoshako, 17(3), p.111 - 117, 2004/05

To reveal the mechanism of oxidative base damages, such as 8-oxo-G, in DNA molecule by ionizing radiation, DNA base radicals were examined around oxygen and nitrogen K-edge region using an EPR spectrometer installed in a synchrotron soft X-ray beamline (BL23SU) in SPring-8. In situ measurements of EPR spectrum of guanine base revealed that short-lived transient radical species are specifically induced by photoexcitation of a 1s electron to $$sigma$$* antibonding orbital at carbonyl oxygen atom. They promptly disappear by "beam-off". On the other hand, a long-lived radical whose EPR spectrum is consistent with previous reports for guanine cation radical was accumulated during the irradiation. The yield of the stable radical decreased by These results indicate that chemically stable DNA base lesions, such as 8-oxo-G, would result from transient species that are inferred to be one electron oxidized radicals after decay of Auger final state.

Journal Articles

Application of electron beams for the treatment of VOC streams

Hirota, Koichi; Sakai, Hiroki*; Washio, Masakazu*; Kojima, Takuji

Industrial & Engineering Chemistry Research, 43(5), p.1185 - 1191, 2004/03

 Times Cited Count:42 Percentile:78.98(Engineering, Chemical)

Twenty volatile organic compounds (VOCs) were irradiated with electron beams in laboratory scale to obtain an electron-beam energy required for a 90% treatment. The experiments showed that the energy was related with the chemical structure and roughly estimated from rate constants for reactions with OH radicals. The cost analysis revealed that the unification of a self-shielding electron accelerator with a reactor could reduce the capital cost for an electron-beam system. Electron-beam technology is a promising method for the treatment of VOCs.

Journal Articles

Electron beam technologies for control of flue gases/wastewaters and their applications

Kojima, Takuji

Oyo Butsuri, 72(4), p.405 - 414, 2003/04

The advanced technologies are required to control pollutants e.g. dioxins in gas or water at extremely low concentration. The present paper introduces typical basic studies, developments of control technologies, and example of their industrial applications of electron beam technology having the features of oxidation, decomposition and detoxifying of such pollutants even at low concentration. It covers removal of SOx and NOx from coal-combustion flue gas, decomposition of gaseous volatile organic compound in off gas and dioxins in incineration flue-gas, purification of tap and wastewaters, and treatment of sewage/sludge.

Journal Articles

Electron-beam treatment of PCDD/Fs in the flue gas from a municipal solid waste incinerator

Hirota, Koichi; Hakoda, Teruyuki; Taguchi, Mitsumasa; Takigami, Machiko*; Kojima, Takuji

Proceedings of 9th International Conference on Radiation Curing (RadTech Asia '03) (CD-ROM), 4 Pages, 2003/00

The flue gas from a municipal solid waste incinerator (MSWI) was irradiated with electron beams to destroy polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). A flue gas of 1,000 m$$^{3}$$/h N for the irradiation was obtained at 200$$^{circ}$$C from a main gas stream of the MSWI. The decomposition efficiencies of PCDD/Fs were increased with absorbed dose and reached 90% at a dose of 14 kGy. The reaction mechanisim for PCDD/Fs was also considered.

Journal Articles

Potential energy surface for the C$$_{2}$$H$$_{4}$$ + Cl$$_{2}$$ $$rightarrow$$ C$$_{2}$$H$$_{4}$$Cl + Cl reaction; Ab initio molecular orbital study

Kurosaki, Yuzuru

Journal of Molecular Structure; THEOCHEM, 545(1-3), p.225 - 232, 2001/07

The CASSCF and MRCI calculations with the cc-pVTZ basis set have been carried out for the C$$_{2}$$H$$_{4}$$ + Cl$$_{2}$$ $$rightarrow$$ C$$_{2}$$H$$_{4}$$Cl + Cl reaction. It has been revealed that the reaction has a small barrier from the C$$_{2}$$H$$_{4}$$Cl + Cl side at the CASSCF level of theory, but it has no barrier at the MRCI level. Namely, the C$$_{2}$$H$$_{4}$$Cl + Cl $$rightarrow$$ C$$_{2}$$H$$_{4}$$ + Cl$$_{2}$$ reaction was predicted to be a spontaneous reaction. The result of the MRCI calculation strongly supports the prediction of our previous PMP4(SDTQ) calculation [J. Mol. Struct. (Theochem) 503 (2000) 231].

Journal Articles

ESR study on chemical crosslinking reaction mechanisms of polyethylene using a chemical agent, 4; Effect of sulfur- and phosphorous-type antioxidants

Yamazaki, Takanori*; Seguchi, Tadao

Journal of Polymer Science, Part A; Polymer Chemistry, 38(17), p.3092 - 3099, 2000/09

no abstracts in English

Journal Articles

Electron spin resonance study on chemical crosslinking reaction mechanisms of polyethelene using a chemical agent, 5; Comparison with polyproplyene and ethylene-propylene copolymer

Yamazaki, Takanori*; Seguchi, Tadao

Journal of Polymer Science, Part A; Polymer Chemistry, 38(18), p.3383 - 3389, 2000/09

no abstracts in English

Journal Articles

ESR study on free radicals trapped in crosslinked polytetrafluoroetylene(PTFE), 2;Radical formation and reactivity

*; Seguchi, Tadao; Tabata, Yoneho*

Radiation Physics and Chemistry, 55(1), p.61 - 71, 1999/00

 Times Cited Count:69 Percentile:97.2(Chemistry, Physical)

no abstracts in English

Journal Articles

Radiation induced free radicals and its behaviors in crosslinked polytetrafluoroethylene (PTFE)

Oshima, Akihiro; Seguchi, Tadao; Tabata, Yoneho*

Proceedings of IUPAC World Polymer Congress 37th International Symposium on Macromolecules (MACRO 98), P. 56, 1998/00

no abstracts in English

Journal Articles

ESR study on free radicals trapped in crosslinked polytetrafluoroethyene (PTFE)

*; Seguchi, Tadao; Tabata, Yoneho*

Radiation Physics and Chemistry, 50(6), p.601 - 606, 1997/00

 Times Cited Count:66 Percentile:96.95(Chemistry, Physical)

no abstracts in English

Journal Articles

Cyclodextrin addition effect on radiation-induced decomposition of chlorophenols in deoxygenated water

X.Huang*; Arai, Hidehiko; Matsuhashi, Shimpei; Miyata, Teijiro

Chemistry Letters, 0(2), p.159 - 160, 1996/00

no abstracts in English

Journal Articles

Enhanced phenol yield from radiation-induced decomposition of chlorophenols in deaerated water by addition of cyclodextrin and glucose

X.Huang*; Arai, Hidehiko; Matsuhashi, Shimpei; Miyata, Teijiro

Chemistry Letters, 0(4), p.273 - 274, 1996/00

no abstracts in English

Journal Articles

Dose intercomparison experiment for gamma rays and 3-MeV electrons by mailing dosimetry using free-radical dosimeters

S.R.Nilekani*; G.R.Narayan*; B.Suseela*; R.M.Bhat*; B.L.Gupta*; Kojima, Takuji; Takizawa, Haruki; Sunaga, Hiromi; Tanaka, Ryuichi

Applied Radiation and Isotopes, 46(3), p.205 - 207, 1995/00

 Times Cited Count:5 Percentile:58.92(Chemistry, Inorganic & Nuclear)

no abstracts in English

Journal Articles

Reaction mechanisms of silicon carbide fiber synthesis by heat treatment of polycarbosilane fibers cured by radiation, II; Free radical reaction

Sugimoto, Masaki; *; *; Seguchi, Tadao

Journal of the American Ceramic Society, 78(7), p.1849 - 1852, 1995/00

 Times Cited Count:37 Percentile:84.7(Materials Science, Ceramics)

no abstracts in English

Journal Articles

Study of polyethylene crosslinking by ESR

Yamazaki, T.*; Seguchi, Tadao

DEI-93-157, 0, p.35 - 44, 1993/12

no abstracts in English

Journal Articles

Heat resistant SiC-fiber synthesis and reaction mechanisms from radiation-cured polycarbosilane fiber

Seguchi, Tadao; Sugimoto, Masaki*; *

High Temperature Ceramic Matrix Composites; 6th European Conf. on Composite Materials: HT-CMC, p.51 - 57, 1993/00

no abstracts in English

61 (Records 1-20 displayed on this page)