JAEA
  • help
  • PC | SP
  • JP | EN
          
Refine your search：     
Report No.
 - 
Clear All
Search Results: Records 1-20 displayed on this page of 37

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

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：5 Percentile：39.86(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：78.08(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：92.78(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：53.93(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：71.63(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：41 Percentile：93.07(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：81.82(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：78.39(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

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 therapeutic ion beam, 1; Measurement of $$^{.}$$OH yield near the Bragg peak

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

no journal, , 

no abstracts in English

Oral presentation

Water radiolysis with therapeutic ion beam; Contribution of fragmentations to $$^{.}$$ OH yields estimated by PHITS

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

no journal, , 

no abstracts in English

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 therapeutic high-energy heavy-ion beams; Yield of OH radical near the Bragg peak

Yamashita, Shinichi; Funtowiez, D.*; Maeyama, Takuya*; Midorikawa, Masamichi*; Oka, Toshitaka; Baldacchino, G.*; Taguchi, Mitsumasa; Kimura, Atsushi; Kudo, Hisaaki*; Katsumura, Yosuke; et al.

no journal, , 

Product yields of water radiolysis are inevitably important in understanding detailed mechanism of indirect action of ionizing radiations. We have conducted yield measurement of main products such as hydrated electron, hydroxyl radical ($$^{.}$$OH) and hydrogen peroxide. We have also developed a sensitive method to determine $$^{.}$$OH yield with a fluorescent probe. In the method, aqueous solution of coumarin-3-carboxylic acid (CCA) is irradiated and $$^{.}$$OH is scavenged by CCA, resulting in production of fluorescent product 7OH-CCA. Applying this method, $$^{.}$$OH yield near the Bragg peak has been measured in this study because the Bragg peak is overlapped cancer position in actual therapy. Beams of C 290 and 135 MeV/u and so on were taken for irradiation at the biological irradiation port at HIMAC facility of NIRS. It was found that $$^{.}$$OH yield show minimal value around the Bragg peak for every ion beam and it drastically jumps up several times at just downstream of the Bragg peak. It is already well known that contributions of fragmentation particles become non-negligible for high-energy heavy ions. Thus, further consideration including fragmentations is necessary to separate contributions of different fragmentation particles. Such consideration is being attempted by using simulations with HIBRAC and PHITS.

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

Water radiolysis with heavy ions of energies up to 28 GeV; Measurement of primary yields and simulation based on diffusion kinetic model

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

no journal, , 

no abstracts in English

Oral presentation

Water radiolysis with relativistic heavy ions from HIMAC; Yield measurements and simulations of track reactions

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

no journal, , 

Water radiolysis with highly energetic heavy ions from helium to iron ions (up to 500 MeV per nucleon, corresponding to beta = 0.758) provided from HIMAC (Heavy Ion Medical Accelerator in Chiba) at NIRS (National Institute of Radiological Sciences) has been investigated through yield measurements and simulations of intra-track reactions. Primary yields, which are defined as yields at sub microsecond after irradiation, were measured for wide range of LET (2.2-700 eV/nm). Dynamics of heavy ion tracks were also discussed based on yield measurement, in which various scavenger concentrations were used. In parallel to the measurements, simulations based on Monte-Carlo method and diffusion kinetic model were conducted.

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.

Oral presentation

Using a fluorescent probe for the OH-yield determination with high-LET particles

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

no journal, , 

Fluorescent probe 7-Hydroxy-coumarin-3-carboxylic acid, which is a product of reaction between Coumarin-3-carboxylic acid (CCA) and hydroxyl radical (OH), was applied to estimation of the yield of OH produced in water radiolysis with heavy ions of energies up to 28 GeV provided from HIMAC (Heavy Ion Medical Accelerator in Chiba). LET was varied from 0.2 for $$gamma$$-ray or fast electron beam to 346 eV/nm for iron ion beam. With changing the concentration of CCA in the range from 0.1 to 26 mM, scavenging time scale was varied from 4 ns to 1 $$mu$$s, at which time scale intra-track reactions between water decomposition radicals including OH are significant.

37 (Records 1-20 displayed on this page)