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Journal Articles

Mechanism of radiation-induced reactions in aqueous solution of coumarin-3-carboxylic acid; Effects of concentration, gas and additive on fluorescent product yield

Yamashita, Shinichi; Baldacchino, G.*; Maeyama, Takuya*; Taguchi, Mitsumasa; Muroya, Yusa*; Lin, M.*; Kimura, Atsushi; Murakami, Takeshi*; Katsumura, Yosuke

Free Radical Research, 46(7), p.861 - 871, 2012/07

 Times Cited Count:15 Percentile:53.87(Biochemistry & Molecular Biology)

Radiation-induced reactions in aqueous solutions of a water-soluble coumarin derivative, coumarin-3-carboxyl acid (C3CA), have been investigated by pulse radiolysis with 35-MeV electron beam, final product analysis after $$^{60}$$Co $${gamma}$$-irradiations, and deterministic model simulations. It was found that C3CA reacts with the hydroxyl radical ($$^{bullet}$$OH) as well as the hydrated electron at nearly diffusion-controlled rate constants: 6.8$${times}$$10$$^{9}$$ and 2.1$${times}$$10$$^{10}$$ M$$^{-1}$$s$$^{-1}$$, respectively. Reactivity of C3CA toward O$$_{2}$$$$^{-}$$$$^{bullet}$$ was not confirmed. Production of a fluorescent molecule 7-hydroxy-coumarin-3-carboxylic acid (7OH-C3CA) was detected by a fluorescence spectrometer coupled with high performance liquid chromatography. Production yields of 7OH-C3CA were in a range from 0.025 to 0.18 (100 eV)$$^{-1}$$, depending on irradiation conditions. A variety of the yield with saturating gas, additive, and C3CA concentration implied that there are at least two pathways from scavenging reaction of C3CA toward $$^{bullet}$$OH to 7OH-C3CA: peroxidation reaction followed by elimination of perhydroxyl radical and disproportionation reaction. A reaction mechanism involving the two pathways was proposed and incorporated into the simulations, showing good explanation of experimentally measured 7OH-C3CA yields with a constant conversion factor from $$^{bullet}$$OH scavenging to 7OH-C3CA production, 4.7%, unless $${t}$$-BuOH is not added.

Journal Articles

Production of a fluorescence probe in ion-beam radiolysis of aqueous coumarin-3-carboxylic acid solution, 2; Effects of nuclear fragmentation and its simulation with PHITS

Maeyama, Takuya*; Yamashita, Shinichi; Taguchi, Mitsumasa; Baldacchino, G.*; Sihver, L.*; Murakami, Takeshi*; Katsumura, Yosuke

Radiation Physics and Chemistry, 80(12), p.1352 - 1357, 2011/12

 Times Cited Count:11 Percentile:31.31(Chemistry, Physical)

Coumari-3-carboxylic acid scavenges OH radical produced in water radiolysis, leading to production of a fluorescence probe at almost constant ratio relative to the amount of the scavenged OH radicals. This was applied in estimation of OH radical yield in water radiolysis especially with therapeutic heavy ions of GeV-class energies, i.e. $$^{12}$$C$$^{6+}$$ beams of 135, 290 and 400 MeV/u. OH yields upstream of the Bragg peaks decreased with increasing penetration depth of the projectile ions while that downstream suddenly jumped up to near the value for low-LET radiations such as $$gamma$$-rays. This is due to low-LET secondary fragmentation ions produced during long trajectory of the primary projectile C ion. Quantitative explanation by nuclear fragmentation simulations with PHITS code was attempted and resulted in 15-45% underestimation in the region behind the Bragg peaks, which would be due to the difference in geometries between irradiations of the sample solutions and dosimetry with a small ionization chamber.

Journal Articles

Production of a fluorescence probe in ion-beam radiolysis of aqueous coumarin-3-carboxylic acid solution, 1; Beam quality and concentration dependences

Maeyama, Takuya*; Yamashita, Shinichi; Baldacchino, G.*; Taguchi, Mitsumasa; Kimura, Atsushi; Murakami, Takeshi*; Katsumura, Yosuke

Radiation Physics and Chemistry, 80(4), p.535 - 539, 2011/04

 Times Cited Count:23 Percentile:10.3(Chemistry, Physical)

Aqueous coumarin-3-carboxylic Acid (3CCA) solutions were irradiated with eight different ion beams covering LET range from 0.5 to above 2000 eV/nm. $$G$$-values of 7OH-3CCA, one of hydroxylated products in radiolysis of the solutions, have been determined by fluorescence-HPLC technique in 3CCA concentration range from 0.1 to 26 mM. The formation yield of 7OH-3CCA increased with increasing concentration of 3CCA while it decreased with increasing LET value of ion beam. Compared with our previous reports on $$G$$($$^{bullet}$$OH) at a scavenging capacity of 10$$^{7}$$ s with absorption spectroscopy, it was found that $$G$$(7OH-3CCA) is about (4.7$$pm$$0.6)% of $$G$$($$^{bullet}$$OH), which is consistent for all of the ion beams used in the present study. However, 7OH-3CCA yields in high CCA concentration region, especially by using extremely high LET ions, were much higher than expected values based on the above conversion factor and $$G$$($$^{bullet}$$OH) value predicted in theoretical work.

Journal Articles

Radiation chemistry of liquid water with heavy ions; Steady-state and pulse radiolysis studies

Yamashita, Shinichi; Taguchi, Mitsumasa; Baldacchino, G.*; Katsumura, Yosuke

Charged Particle and Photon Interactions with Matter; Recent Advances, Applications, and Interfaces, p.325 - 354, 2010/12

Irradiation effects induced by heavy ions are much different from those by low-LET radiations. Such distinctiveness has been applied to cancer therapy, surface processing, analytical techniques, and so on. However, detailed mechanism through which such distinctiveness appears has not been clarified yet. In this chapter, what have experimentally been found recently, especially within these five years, in water radiolysis with positively-charged atomic heavy ions are shown. Steady-state radiolysis studies and pulse radiolysis studies are separately summarized because these two approaches inherently involve own advantages and limitations. Gathering reported products yields and kinetics, track structures and intra-track dynamics are discussed. One of the most characteristic features of recent studies is that track-segment or -differential yields were intensively measured compared to earlier studies.

Journal Articles

Radiolysis of supercritical water

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

Recent Trends in Radiation Chemistry, p.255 - 277, 2010/05

In this review paper, we have summarized the important results obtained in the last decade concerning the radiation chemistry studies on high temperature and supercritical water, especially the radiolytic yields of water decomposition products, the reaction rate constants, and the spectral properties of transient species, etc. The importance of density effects under supercritical conditions is pointed out.

Journal Articles

Transient absorption measurement system using pulsed energetic ion

Taguchi, Mitsumasa; Baldacchino, G.*; Kurashima, Satoshi; Kimura, Atsushi; Sugo, Yumi; Katsumura, Yosuke*; Hirota, Koichi

Radiation Physics and Chemistry, 78(12), p.1169 - 1174, 2009/12

 Times Cited Count:4 Percentile:65.63(Chemistry, Physical)

no abstracts in English

Journal Articles

Determination of the time-dependent OH-yield by using a fluorescent probe; Application to heavy ion irradiation

Baldacchino, G.*; Maeyama, Takuya*; Yamashita, Shinichi; Taguchi, Mitsumasa; Kimura, Atsushi; Katsumura, Yosuke; Murakami, Takeshi*

Chemical Physics Letters, 468(4-6), p.275 - 279, 2009/01

 Times Cited Count:30 Percentile:23.23(Chemistry, Physical)

This paper reports a sensitive method using HPLC-fluorescence detection of $$^{bullet}$$OH in liquid water under high-energy heavy-ion irradiation. The coumarin-3-carboxylic-acid (3CCA) molecule was selected for probing $$^{bullet}$$OH and providing the fluorescent 7-hydroxy-coumarin-3-carboxylic-acid (7OH-3CCA). Since the concentration limit achievable is better than 1 nM, the radiolytic yields were determined with a sensitivity of 2$$times$$10$$^{-9}$$ mol/J for 4.8-GeV-$$^{12}$$C$$^{6+}$$ of and 20-GeV-$$^{40}$$Ar$$^{18+}$$ in the ns time-range. They decrease with the linear energy transfer from 2.8$$times$$10$$^{-7}$$ to 1.3$$times$$10$$^{-7}$$ mol/J ($$^{12}$$C$$^{6+}$$ of 11 eV/nm) and 1.5$$times$$10$$^{-7}$$ to 0.9$$times$$10$$^{-7}$$ mol/J ($$^{40}$$Ar$$^{18+}$$ of 90 eV/nm) which is in agreement with the literature data.

Journal Articles

Development of optical system for direct observation of behavior of transient species under pulsed-heavy ion irradiation

Taguchi, Mitsumasa; Kimura, Atsushi; Hirota, Koichi; Kurashima, Satoshi; Baldacchino, G.*; Katsumura, Yosuke*

JAEA-Review 2007-060, JAEA Takasaki Annual Report 2006, P. 158, 2008/03

no abstracts in English

Journal Articles

Characteristics study on suspended fine particles in aqueous phenol solution formed by electron beam irradiations

Taguchi, Mitsumasa; Zennyoji, Yoshihiro*; Takigami, Machiko*; Baldacchino, G.*; Kimura, Atsushi; Hiratsuka, Hiroshi*; Namba, Hideki; Kojima, Takuji

Radiation Physics and Chemistry, 75(5), p.564 - 571, 2006/03

 Times Cited Count:6 Percentile:55.2(Chemistry, Physical)

The suspended fine particles formed in aqueous phenol solution under high dose irradiation were studied using the MeV electron beam and $$^{60}$$Co $$gamma$$-ray irradiations. The fine particle's size was 100-800 nm in diameter and became bigger at higher dose and lower dose rate. The distributions of the particle size became narrower for irradiation at higher dose rate. The fine particles were regarded to consist of molecules of about 1.9$$times$$10$$^{2}$$ molecular weight.

Oral presentation

Direct observation of superoxide radicals produced in water by 70 MeV/u Kr ion irradiations

Taguchi, Mitsumasa; Baldacchino, G.*; Pin, S.*; Vigneron, G.*; Hichel, B.*; Kojima, Takuji

no journal, , 

no abstracts in English

Oral presentation

Water radiolysis with extreme conditions of temperature and LET; Application to the nuclear industry

Baldacchino, G.*; Taguchi, Mitsumasa; Hichel, B.*

no journal, , 

no abstracts in English

Oral presentation

Development of optical system for direct observation of behavior of transient species under heavy ion irradiation

Taguchi, Mitsumasa; Kimura, Atsushi; Hirota, Koichi; Kurashima, Satoshi; Baldacchino, G.*; Katsumura, Yosuke*

no journal, , 

no abstracts in English

Oral presentation

Water radiolysis with heavy-ion beams, 1; Yield measurements of water decomposition products

Maeyama, Takuya*; Katsumura, Yosuke; Yamashita, Shinichi*; Lin, M.; Muroya, Yusa*; Miyazaki, Toyoaki*; Murakami, Takeshi*; Baldacchino, G.*

no journal, , 

no abstracts in English

Oral presentation

On OH radicals in water under heavy ion irradiation

Taguchi, Mitsumasa; Kimura, Atsushi; Baldacchino, G.*; Katsumura, Yosuke*; Hirota, Koichi

no journal, , 

Heavy ions give unique irradiation effects on target materials. Reactions in water under heavy ion irradiation are mainly induced by OH (hydroxyl) radicals. OH radicals yields have been investigated by the (1) product analysis and (2) pulse radiolysis methods. (1) Aqueous phenol solutions were irradiated with He, C and Ne ions. The yields of the OH radicals were estimated by analyzing the yields of the irradiation products of phenol. The yields of the OH radicals increased with the specific energy, but decreased with both the mass of each ion and elapsed time. (2) Transient absorption measurement system was developed for the direct observation of radical behaviors in water under heavy ion irradiation. A small absorbance change less than 10$$^{-4}$$ was recorded. The transient absorbance of (SCN)$$_{2}$$$$^{-}$$ formed by the reaction of OH radicals with SCN$$^{-}$$ in aqueous KSCN solution was observed under pulsed C ion irradiation.

Oral presentation

Development of pulse radiolysis system for spectroscopic observation of transient species under heavy ion irradiation

Taguchi, Mitsumasa; Kimura, Atsushi; Hirota, Koichi; Kurashima, Satoshi; Baldacchino, G.*; Katsumura, Yosuke*

no journal, , 

no abstracts in English

Oral presentation

Development of transient absorption measurement system for heavy ion radiolysis in TIARA facility

Taguchi, Mitsumasa; Baldacchino, G.*; Kurashima, Satoshi; Kimura, Atsushi; Katsumura, Yosuke*; Hirota, Koichi

no journal, , 

no abstracts in English

Oral presentation

Development of transient absorption measurement system for pulsed-heavy ion irradiation

Taguchi, Mitsumasa; Baldacchino, G.*; Kimura, Atsushi; Kurashima, Satoshi; Hirota, Koichi

no journal, , 

no abstracts in English

Oral presentation

Sensitive measurements of $$^{.}$$OH yields with fluorescent probe, 1; Investigation into reaction mechanism and reactivity toward water decomposition radicals of coumarin-3-carboxylic acid

Maeyama, Takuya*; Yamashita, Shinichi; Baldacchino, G.*; Muroya, Yusa*; Taguchi, Mitsumasa; Kimura, Atsushi; Katsumura, Yosuke

no journal, , 

no abstracts in English

Oral presentation

Sensitive measurement of OH yield with fluorescent probe, 2; Evaluation of temporal behavior of OH yield after high-energy heavy-ion irradiation

Maeyama, Takuya*; Yamashita, Shinichi; Baldacchino, G.*; Taguchi, Mitsumasa; Kimura, Atsushi; Katsumura, Yosuke; Murakami, Takeshi*

no journal, , 

no abstracts in English

Oral presentation

Sensitive yield measurement of OH in water radiolysis at the Bragg peak of high; Energy heavy-ions with CCA as a fluorescent probe

Maeyama, Takuya*; Yamashita, Shinichi; Baldacchino, G.*; Katsumura, Yosuke; Taguchi, Mitsumasa; Kimura, Atsushi; Muroya, Yusa*; Murakami, Takeshi*

no journal, , 

Detailed mechanism in which effectiveness of heavy ions in cancer therapy are derived from is not known well. It is inevitably important to examine water radiolysis with high-energy heavy ions because water is main component of human body. Among several water decomposition products, OH is known to be most responsible for radiation induced cell death in indirect actions. OH yield has been reported for heavy-ion irradiations in several works employing absorption analyses. With increasing LET, OH yield decreases monotonically (at least up to several hundred eV per nm). Then, more sensitive way to determine OH yield is preferable for higher LET region. In this work, a fluorescent probe, coumarin-3-carboxylic acid, was applied for OH-yield determination as a sensitive way of quantification of OH radical production. Especially, OH yield near the Bragg peaks was discussed.

41 (Records 1-20 displayed on this page)