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Journal Articles

Repeatability and reproducibility of measurements of low dissolved radiocesium concentrations in freshwater using different pre-concentration methods

Kurihara, Momo*; Yasutaka, Tetsuo*; Aono, Tatsuo*; Ashikawa, Nobuo*; Ebina, Hiroyuki*; Iijima, Takeshi*; Ishimaru, Kei*; Kanai, Ramon*; Karube, Jinichi*; Konnai, Yae*; et al.

Journal of Radioanalytical and Nuclear Chemistry, 322(2), p.477 - 485, 2019/11

https://doi.org/10.1007/s10967-019-06696-2
 Times Cited Count：6 Percentile：55.39(Chemistry, Analytical)

We assessed the repeatability and reproducibility of methods for determining low dissolved radiocesium concentrations in freshwater in Fukushima. Twenty-one laboratories pre-concentrated three of 10 L samples by five different pre-concentration methods (prussian-blue-impregnated filter cartridges, coprecipitation with ammonium phosphomolybdate, evaporation, solid-phase extraction disks, and ion-exchange resin columns), and activity of radiocesium was measured. The z-scores for all of the $$^{137}$$Cs results were within $$pm$$2, indicating that the methods were accurate. The relative standard deviations (RSDs) indicating the variability in the results from different laboratories were larger than the RSDs indicating the variability in the results from each separate laboratory.

Journal Articles

The Air dose rate around the Fukushima Dai-ichi Nuclear Power Plant; Its spatial characteristics and temporal changes until December 2012

Mikami, Satoshi; Maeyama, Takeshi*; Hoshide, Yoshifumi*; Sakamoto, Ryuichi*; Sato, Shoji*; Okuda, Naotoshi*; Sato, Tetsuro*; Takemiya, Hiroshi; Saito, Kimiaki

Journal of Environmental Radioactivity, 139, p.250 - 259, 2015/01

https://doi.org/10.1016/j.jenvrad.2014.08.020
 Times Cited Count：49 Percentile：77.12(Environmental Sciences)

Journal Articles

Spatial distributions of radionuclides deposited onto ground soil around the Fukushima Dai-ichi Nuclear Power Plant and their temporal change until December 2012

Mikami, Satoshi; Maeyama, Takeshi*; Hoshide, Yoshifumi*; Sakamoto, Ryuichi*; Sato, Shoji*; Okuda, Naotoshi*; Demongeot, S.*; Gurriaran, R.*; Uwamino, Yoshitomo*; Kato, Hiroaki*; et al.

Journal of Environmental Radioactivity, 139, p.320 - 343, 2015/01

https://doi.org/10.1016/j.jenvrad.2014.09.010
 Times Cited Count：102 Percentile：92.58(Environmental Sciences)

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

https://doi.org/10.3109/10715762.2012.684879
 Times Cited Count：26 Percentile：53.21(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

https://doi.org/10.1016/j.radphyschem.2011.07.004
 Times Cited Count：15 Percentile：71.11(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

https://doi.org/10.1016/j.radphyschem.2010.11.013
 Times Cited Count：42 Percentile：93.17(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

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

https://doi.org/10.1016/j.cplett.2008.12.006
 Times Cited Count：44 Percentile：81.49(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

Water radiolysis with heavy ions of energies up to 28 GeV, 2; Extension of primary yield measurements to very high LET values

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

Radiation Physics and Chemistry, 77(10-12), p.1224 - 1229, 2008/10

https://doi.org/10.1016/j.radphyschem.2008.05.037
 Times Cited Count：22 Percentile：78.05(Chemistry, Physical)

Measurements of primary ${it g}$-values (at $$sim$$ 10$$^{-7}$$ s after the initial ionizing event) of e$$^{-}$$$$_{aq}$$, $$^{.}$$OH and H$$_{2}$$O$$_{2}$$ were extended to the very high linear energy transfer (LET) region ($$sim$$ 700 eV per nm) near the Bragg peak. Heavy ions ($$^{4}$$He$$^{2+}$$, $$^{12}$$C$$^{6+}$$, $$^{20}$$Ne$$^{10+}$$, $$^{28}$$Si$$^{14+}$$, $$^{40}$$Ar$$^{18+}$$ and $$^{56}$$Fe$$^{26+}$$) of energies up to 28 GeV were provided by the Heavy Ion Medical Accelerator in Chiba (HIMAC) of the National Institute of Radiological Sciences (NIRS) in Chiba, Japan. Energies of the ions were decreased down to about 10 MeV per u for $$^{4}$$He$$^{2+}$$ using an energy absorber made of polymethylmethacrylate (PMMA) plates in order to vary the LET values. Beam was visualized after passing through the energy absorber using agarose gel of aqueous solution containing methyl viologen and sodium formate in order to determine how long ions can penetrate into water. Based on the information of the penetration depth of ions in samples, much attention was paid to dose correction and LET evaluation. The obtained data were plotted as a function of (${it Z}$ $$_{eff}$$/$$beta$$)$$^{2}$$ also instead of LET in order to discuss effects of physical track structures on product yields, resulted in better universality.

Oral presentation

Ion beam radiation chemistry relevant to radiation therapy

Katsumura, Yosuke; Yamashita, Shinichi; Lin, M.; Maeyama, Takuya*; Muroya, Yusa*; Baldacchino, G.*; Jay-Gerin, J.-P.*; Meesungnoen, J.*; Murakami, Takeshi*

no journal, , 

Oral presentation

Radiolysis of CCA aqueous solution; OH-scavenging and mechanism of fluorescent probe production

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

no journal, , 

no abstracts in English

Oral presentation

Water radiolysis with heavy ions; Correlation between heavy-ion track structure and primary yields

Yamashita, Shinichi; Katsumura, Yosuke; Maeyama, Takuya*; Murakami, Takeshi*; Meesungnoen, J.*; Jay-Gerin, J.-P.*

no journal, , 

Primary yields in water radiolysis with relativistic heavy ions from Heavy Ion Medical Accelerator in Chiba (HIMAC) of National Institute of Radiological Sciences (NIRS) have been measured covering wide range of beam conditions. Experimental results were summarized and compared with results obtained not only in a deterministic simulation but also in a stochastic one. Heavy-ion track structure was discussed from microscopic viewpoints based on the experimental and simulation results.

Oral presentation

Water radiolysis with heavy ions; Measurement of $$^{.}$$OH yield near the Bragg peak

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

no journal, , 

Aqueous solution of Coumarin-3-carboxylic acid (CCA) has been applied to yield measurement of $$^{.}$$OH in water. Production yield of a fluorescent probe, 7OH-CCA, which is a stable product produced after scavenging reaction for $$^{.}$$OH by CCA, was determined by using HPLC connected to a fluorometer. Taking sensitiveness of fluorometry as an advantage, $$^{.}$$OH yields near the Bragg peaks, which are known very small compared to those in plateau LET region, have been measured. Contribution of fragmentations, which are known to be significant near the Bragg peaks of high-energy heavy ions, is also being discussed.

Oral presentation

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

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

no journal, , 

no abstracts in English

Oral presentation

Yield determination of $$bullet$$OH with therapeutic ion beam

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

no journal, , 

Solution of Coumarin-3-carboxylic acid (CCA) has been applied to yield measurement of $$bullet$$OH in water radiolysis with carbon ion beams. Production yield of a fluorescent probe, 7OH-CCA, which is a stable product produced after scavenging reaction for $$bullet$$OH by CCA, was determined by using HPLC connected to a fluorometer. By using this chemical system, $$bullet$$OH yields near the Bragg peak have been measured. Contribution of fragmentations, which are known to be significant near the Bragg peak of high-energy heavy ions, is also discussed by conducting fragmentation simulation with deterministic, semi-empirical and one-dimensional code named HIBRAC.

Oral presentation

Water radiolysis with heavy ions

Yamashita, Shinichi; Katsumura, Yosuke; Maeyama, Takuya*; Lin, M.; Muroya, Yusa*; Murakami, Takeshi*; Meesungnoen, J.*; Jay-Gerin, J.-P.*

no journal, , 

Water radiolysis with high-energy heavy ions has been investigated through measurement of product yield and simulation of intra-track reactions. Ions from helium to xenon of energies up to 500 MeV per nucleon were taken for irradiation at the biological irradiation port of HIMAC installed at NIRS, Japan. Taking long range of the ions, typically longer than 10 cm, as an advantage, track-segment yields of main water decomposition products, e$$^{-}$$$$_{aq}$$, $$bullet$$OH and H$$_{2}$$O$$_{2}$$, have been determined. Utilizing energy absorber made of PMMA, ion energies were decreased down to about 10 MeV per nucleon to vary beam properties in sample solutions, and then, product yields for wide ranges of ion types and energies were accumulated. Influences of scavenger concentration have also been discussed and yield of approximate sum of $$bullet$$OH, H$$bullet$$ and e$$^{-}$$$$_{aq}$$ was measured. In parallel to these measurements, Monte-Carlo simulation of intra-track reactions has been conducted not only to reproduce the experimental results but also to discuss further track structure and its dynamics from microscopic viewpoint.

Oral presentation

Yield of OH near the Bragg peak of heavy-ion beam from HIMAC

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

no journal, , 

Cancer therapy needs ions of several GeV to attain sufficiently long penetration depth into human body (normally 30 cm) to treat cancer in deep position. While advantages of heavy ion therapy are well-known phenomenologically, details of mechanism in which heavy ion irradiation leads to distinctive biological effectiveness have not been clarified yet. Then, understanding of water radiolysis with heavy ions is necessary because water is main component of human body. Aqueous solution of Coumarin-3-carboxylic acid (CCA) has been applied to yield-measurement of $$^{.}$$OH produced in water radiolysis with therapeutic carbon ion beam provided from HIMAC at NIRS. Production yield of a fluorescent probe, 7OH-CCA, which is a stable product produced after scavenging reaction for $$^{.}$$OH by CCA, was determined by using HPLC connected to a fluorometer. By using this chemical system, $$^{.}$$OH yields near the Bragg peak have been measured. Contribution of fragmentations, which are known to be significant near the Bragg peak of high-energy heavy ions, is also discussed by conducting fragmentation simulation.

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

Water radiolysis near the Bragg peak of therapeutic heavy ions, 1; Measurement of OH yield with a fluorescent probe

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

no journal, , 

Recently, cancer therapy with high-energy heavy ions has been utilized, showing high efficiency in actual treatment. While its effectiveness has already been certificated phenomenologically, detailed mechanism through which such a feature appears has not been clarified yet. Water is a main component of human body, and then, it is inevitably important to comprehend water radiolysis. In this study, water radiolysis near the Bragg peak was focused on because the peak is overlapped to cancer in actual treatment, and yield of hydroxyl radical ($$^{.}$$OH) has been determined because $$^{.}$$OH is assumed as a species most responsible to indirect action. In addition, contribution of fragmentation reactions which is significant for high-energy heavy ions were discussed from the viewpoint of $$^{.}$$OH yield.

Oral presentation

Measurement of OH yields around the Bragg Peak with therapeutic carbon ion beams and its simulation with the PHITS code

Maeyama, Takuya*; Yamashita, Shinichi; Baldacchino, G.*; Taguchi, Mitsumasa; Kimura, Atsushi; Muroya, Yusa*; Kudo, Hisaaki*; Oka, Toshitaka; Sato, Tatsuhiko; Katsumura, Yosuke; et al.

no journal, , 

no abstracts in English

Oral presentation

Water radiolysis with heavy ions of energies up to 28 GeV

Yamashita, Shinichi; Katsumura, Yosuke; Maeyama, Takuya*; Baldacchino, G.*; Murakami, Takeshi*; Meesungnoen, J.*; Jay-Gerin, J.-P.*

no journal, , 

Water radiolysis with heavy ions has been investigated from the viewpoint of correlation between track structure and yields of water decomposition products. Primary yields of main products were determined for wide variety of heavy ion beams of energies up to 28 GeV provided at HIMAC (Heavy Ion Medical Accelerator in Chiba). A fluorescent probe, 7-hydroxyl-coumarin-3-carboxylic acid, was utilized in sensitive detection and quantification of hydroxyl radical. This method was extended to investigation of water radiolysis near the Bragg peak with considering fragmentation reactions. Gaseous products detection has also been started.

37 (Records 1-20 displayed on this page)