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Tamura, Koji; Nakanishi, Ryuzo; Oba, Hironori; Karino, Takahiro; Shibata, Takuya; Taira, Takunori*; Wakaida, Ikuo
Journal of Nuclear Science and Technology, 61(8), p.1109 - 1116, 2024/08
Times Cited Count:1 Percentile:23.64(Nuclear Science & Technology)Ishikawa, Akihisa; Koba, Yusuke*; Furuta, Takuya; Chang, W.*; Yonai, Shunsuke*; Matsumoto, Shinnosuke*; Hashimoto, Shintaro; Hirai, Yuta*; Sato, Tatsuhiko
Radiological Physics and Technology, 17(2), p.553 - 560, 2024/06
Sekine, Yurina; Nankawa, Takuya; Hiroi, Kosuke; Oba, Yojiro*; Nagakawa, Yoshiyasu*; Sugita, Tsuyoshi; Shibayama, Yuki; Ikeda-Fukazawa, Tomoko*
Carbohydrate Polymers, 327, p.121538_1 - 121538_11, 2024/03
Times Cited Count:12 Percentile:87.28(Chemistry, Applied)We describe non-toxic, tough nanocellulose (NC) hydrogels formed from chemically unmodified NC by cellulose crystalline transformation and subsequent freeze cross-linking reaction. Using low-concentration NaOH and freezing together induced the crystalline transformation of NC from cellulose I to II via freeze concentration. After the crystalline transformation, cross-linking between the NC and CA in the freeze concentration layer (FCL) provided a strong NC network structure, forming NC hydrogels with high mechanical strength. The freeze-cross-linked NC hydrogel easily retained powder adsorbents in its inner space by mixing the NC-NaOH sol and the powder, and the hydrogel showed high removal efficiency for heavy metals. The results highlight the versatility of chemically unmodified celluloses in developing functional materials, suggest possible practical applications.
Koyama, Shinichi; Ikeuchi, Hirotomo; Mitsugi, Takeshi; Maeda, Koji; Sasaki, Shinji; Onishi, Takashi; Tsai, T.-H.; Takano, Masahide; Fukaya, Hiroyuki; Nakamura, Satoshi; et al.
Hairo, Osensui, Shorisui Taisaku Jigyo Jimukyoku Homu Peji (Internet), 216 Pages, 2023/11
In FY 2021 and 2022, JAEA perfomed the subsidy program for "the Project of Decommissioning and Contaminated Water Management (Development of Analysis and Estimation Technology for Characterization of Fuel Debris (Development of Technologies for Enhanced Analysis Accuracy, Thermal Bahavior Estimation, and Simplified Analysis of Fuel Debris)" started in FY 2021. This presentation material summarized the results of the project, which will be available shortly on the website of Management Office for the Project of Decommissioning, Contaminated Water and Treated Water Management.
Miura, Daisuke*; Sekine, Yurina; Nankawa, Takuya; Sugita, Tsuyoshi; Oba, Yojiro; Hiroi, Kosuke; Ozawa, Tatsuhiko
Carbohydrate Polymer Technologies and Applications (Internet), 4, p.100251_1 - 100251_9, 2022/12
The reaction mechanism of carboxymethyl cellulose nanofiber (CMCF) hydrogel formed by freeze-crosslinking was investigated. We succeeded in observing the hierarchical structural changes during the freeze-crosslinking reaction. Freeze-crosslinked CMCF hydrogels exhibited a characteristic hierarchical alignment structure from the angstrom to micrometer scale that differed from normal cross-linked CMCF hydrogels produced by a conventional method without freezing. It was shown that the characteristic hierarchical structure contributes the excellent mechanical properties of freeze-crosslinked CMCF hydrogels.
Furuta, Takuya; Koba, Yusuke*; Hashimoto, Shintaro; Chang, W.*; Yonai, Shunsuke*; Matsumoto, Shinnosuke*; Ishikawa, Akihisa*; Sato, Tatsuhiko
Physics in Medicine & Biology, 67(14), p.145002_1 - 145002_15, 2022/07
Times Cited Count:8 Percentile:68.93(Engineering, Biomedical)Carbon ion radiotherapy has an advantage over conventional radiotherapy such that its superior dose concentration on the tumor helps to reduce unwanted dose to surrounding normal tissues. Nevertheless, a little dose to normal tissues, which is a potential risk of secondary cancer, is still unavoidable. The Monte Carlo simulation is a good candidate for the tool to assess secondary cancer risk, including the contributions of secondary particles produced by nuclear reactions. We therefore developed a new dose reconstruction system implementing PHITS as the engine. In this system, the PHITS input is automatically created from the DICOM data sets recorded in the treatment planning. The developed system was validated by comparing to experimental dose distribution in water and treatment plan on an anthropomorphic phantom. This system will be used for retrospective studies using the patient data in National Institute for Quantum and Science and Technology.
Saeki, Morihisa*; Matsumura, Daiju; Nakanishi, Ryuzo*; Yomogida, Takumi; Tsuji, Takuya; Saito, Hiroyuki*; Oba, Hironori*
Journal of Physical Chemistry C, 126(12), p.5607 - 5616, 2022/03
Times Cited Count:2 Percentile:12.33(Chemistry, Physical)The reaction mechanism of the direct photoreduction of a Rh ion complex to a Rh
species induced by pulsed ultraviolet laser irradiation was studied using dispersive X-ray absorption fine structure (DXAFS) spectroscopy. The time-resolved X-ray absorption near edge structure (XANES) showed the absence of isosbestic points and suggested that more than two Rh
species contribute toward the direct photoreduction of Rh
. Analysis of the time-resolved XANES data by singular value deposition showed that the direct photoreduction involves three Rh
species. Multivariate curve resolution by alternating least-squares analysis (MCR-ALS) of the time-resolved XANES data gave pure spectra and concentration profiles of the three Rh
species. The Rh
species were assigned to Rh
, Rh
, and Rh
species based on the features of the pure XANES spectra. The concentration profiles suggested that the direct photoreduction proceeds in the order of Rh
Rh
Rh
. A reaction mechanism, which was proposed involving photoreductions of Rh
and Rh
, photoinduced autocatalytic reductions of Rh
and Rh
, and photooxidation of Rh
, well reproduced the concentration profiles of three Rh
species.
Chang, W.*; Koba, Yusuke*; Furuta, Takuya; Yonai, Shunsuke*; Hashimoto, Shintaro; Matsumoto, Shinnosuke*; Sato, Tatsuhiko
Journal of Radiation Research (Internet), 62(5), p.846 - 855, 2021/09
Times Cited Count:4 Percentile:32.45(Biology)With the aim of developing a revaluation tool of treatment plan in carbon-ion radiotherapy using Monte Carlo (MC) simulation, we propose two methods; one is dedicated to identify realistic-tissue materials from a CT image with satisfying the well-calibrated relationship between CT numbers and stopping power ratio (SPR) provided by TPS, and the other is to estimate dose to water considering the particle- and energy-dependent SPR between realistic tissue materials and water. We validated these proposed methods by computing depth dose distribution in homogeneous and heterogeneous phantoms composed of human tissue materials and water irradiated by a 400 MeV/u carbon beam with 8 cm SOBP using a MC simulation code PHITS and comparing with results of conventional treatment planning system (TPS). Our result suggested that use of water as a surrogate of real tissue materials, which is adopted in conventional TPS, is inadequate for dose estimation from secondary particles because their production rates cannot be scaled by SPR of the primary particle in water. We therefore concluded that the proposed methods can play important roles in the reevaluation of the treatment plans in carbon-ion radiotherapy.
Oikawa, Kenichi; Harjo, S.; Pham, A. H.*; Kawasaki, Takuro; Morito, Shigekazu*; Kiyanagi, Yoshiaki*; Shinohara, Takenao; Kai, Tetsuya; Oba, Takuya*; Ito, Masakazu*
JPS Conference Proceedings (Internet), 33, p.011062_1 - 011062_6, 2021/03
Saeki, Morihisa*; Yomogida, Takumi; Matsumura, Daiju; Saito, Takumi*; Nakanishi, Ryuzo*; Tsuji, Takuya; Oba, Hironori*
Analytical Sciences, 36(11), p.1371 - 1378, 2020/11
Times Cited Count:6 Percentile:20.69(Chemistry, Analytical)We measured X-ray absorption fine structure (XAFS) and Raman spectra of isopolymolybdates(VI) in HNO solution (0.15- 4.0 M), which change their geometries depending on acid concentration, and performed simultaneous resolution of the XAFS and Raman data using a multivariate curve resolution by alternating least-squares (MCR-ALS) analysis. In iterative ALS optimization, initial data matrices were prepared by two different methods. The MCR-ALS result of single XAFS data matrix shows large dependence on the preparation method of the initial data matrices. The MCR-ALS result of an augmented matrix of Raman and XAFS data has little dependence on the initial data matrices. It indicates that the augmentation method effectively improves the rotation ambiguities in the MCR-ALS analysis of the XAFS data. Based on the model fitting of the pure EXAFS oscillations, we revealed the change of [Mo
O
(H
O)
]
[Mo
O
(H
O)
]
[HMoO
(H
O)
]
in the highly concentrated HNO
solution.
Oikawa, Kenichi; Kiyanagi, Yoshiaki*; Sato, Hirotaka*; Omae, Kazuma*; Pham, A.*; Watanabe, Kenichi*; Matsumoto, Yoshihiro*; Shinohara, Takenao; Kai, Tetsuya; Harjo, S.; et al.
Materials Research Proceedings, Vol.15, p.207 - 213, 2020/02
Saeki, Morihisa*; Matsumura, Daiju; Yomogida, Takumi; Taguchi, Tomitsugu*; Tsuji, Takuya; Saito, Hiroyuki*; Oba, Hironori*
Journal of Physical Chemistry C, 123(1), p.817 - 824, 2019/01
Times Cited Count:17 Percentile:52.72(Chemistry, Physical)Reaction kinetics of laser-induced particle formation in an aqueous solution of PdCl was investigated by transmission electron microscope (TEM) and dispersive X-ray absorption fine structure (DXAFS). The Pd particle was generated by irradiation of nanosecond pulsed 266-nm laser. The TEM observation showed dependence of the particle size on the laser fluence and promotion of the particle growth by irradiation of high-fluence laser. The DXAFS data give us the Pd
concentration. Temporal changes of the Pd
concentration analyzed based on Finke-Watzky two step mechanism. The analysis elucidates that the laser photon contributes to the reduction of the PdCl
ion by the one-photon process and to the autocatalytic growth of the Pd particles by the multi-photon process.
Saeki, Morihisa*; Taguchi, Tomitsugu*; Oba, Hironori*; Matsumura, Daiju; Tsuji, Takuya; Yomogida, Takumi
Denki Gakkai Kenkyukai Shiryo, Denshi Zairyo Kenkyukai (EFM-17-010021), p.15 - 18, 2017/09
Irradiation of nanosecond pulsed UV laser into a solution of palladium ion leads to formation of palladium particles with sub-micron size particles by time-resolved X-ray absorption spectroscopy.
Yamaguchi, Mika; Hidaka, Akihide; Ikuta, Yuko; Murakami, Kenta*; Tomita, Akira*; Hirose, Hiroya*; Watanebe, Masanori*; Ueda, Kinichi*; Namaizawa, Ken*; Onose, Takatoshi*; et al.
JAEA-Review 2017-002, 60 Pages, 2017/03
Since 2010, IAEA has held the NEM School to develop future leaders who plan and manage nuclear energy utilization in their county. Since 2012, JAEA together with Japan Nuclear HRD Network, University of Tokyo, Japan Atomic Industrial Forum and JAIF International Cooperation Center have cohosted the school in Japan in cooperation with IAEA. Since then, the school has been held in Japan every year. In 2006, Japanese nuclear technology and experience, such as lessons learned from the Fukushima Daiichi Nuclear Power Plant accident, were provided to offer a unique opportunity for the participants to learn about particular cases in Japan. Through the school, we contributed to the internationalization of Japanese young nuclear professionals, development of nuclear human resource of other countries including nuclear newcomers, and enhanced cooperative relationship with IAEA. Additionally, collaborative relationship within the network was strengthened by organizing the school in Japan.
Kushida, Hiroaki*; Fukuda, Kodai*; Terai, Tomoyuki*; Fukuda, Takashi*; Kakeshita, Tomoyuki*; Oba, Takuya*; Osakabe, Toyotaka; Kakurai, Kazuhisa; Kato, Kenichi*
Journal of Physics; Conference Series, 165, p.012054_1 - 012054_4, 2009/06
Onuma, Yuichi; Ishida, Takuya; Sakata, Ikuma*; Kodaira, Akira*; Sakai, Jun*; Oba, Seiichiro*; Kanno, Masaru; Saito, Takashi; Kinase, Muneyuki*; Ishitsuka, Etsuo
JAEA-Technology 2008-078, 39 Pages, 2008/12
Decommissioning of the water loop irradiation facility polluted by fission products and cruds was studied, and the reasonable waste classification occurring by the decommissioning was also studied. A out-pile equipment of the irradiation loop facility installed in JMTR is considered as a decommissioning object. Measurement of ambient dose rate in the out-pile facility and evaluation of the deposited radionuclide concentration in the cooling pipe were carried. In result, it was clear that the significant radionuclide is Co, and that occurred waste can classify as the shallow-ground trench disposal level, clearance level, non-radioactive waste. Furthermore, through the investigation of the cutting method for minimizing secondary waste generation, plumbing cutting machine with preventing scattering function was developed by trial manufactured cutter that surrounds the cutting pipe by box.
Kushida, Hiroaki*; Fukuda, Kodai*; Terai, Tomoyuki*; Fukuda, Takashi*; Kakeshita, Tomoyuki*; Oba, Takuya*; Osakabe, Toyotaka; Kakurai, Kazuhisa; Kato, Kenichi*
European Physical Journal; Special Topics, 158(1), p.87 - 92, 2008/05
Times Cited Count:22 Percentile:71.26(Physics, Multidisciplinary)Chang, W.*; Koba, Yusuke*; Furuta, Takuya; Yonai, Shunsuke*; Hashimoto, Shintaro; Matsumoto, Shinnosuke*; Sato, Tatsuhiko
no journal, ,
In the treatment planning system (TPS) for radiotherapy, approximate calculation by replacing all materials with water and accounting only the density variation is adopted to reduce the computational cost. On the other hand, conversion from patient CT data to elemental compositions and densities is required to conduct Monte Carlo simulation. Especially for the assessment of secondary cancer risk in carbon therapy, secondary particles produced in the nuclear reaction between incident carbons and human tissues are important so that the difference of the elemental compositions is essential. We have therefore developed a method to convert CT number to human tissues keeping the consistency with the water stopping power table embedded in TPS. We applied this conversion method to 9 different human tissues and confirmed the range of carbon beams are reproduced within 1 mm precision for all the materials.
Saeki, Morihisa*; Yomogida, Takumi; Matsumura, Daiju; Nakanishi, Ryuzo*; Taguchi, Tomitsugu*; Tsuji, Takuya; Saito, Hiroyuki*; Oba, Hironori*
no journal, ,
In the absence of a photoactivator, the laser-induced particle formation in an HO/ EtOH solution of PdCl
was performed by three kinds of irradiation condition using fourth harmonics of the pulsed UV laser (266 nm). In the irradiation, pulsed laser energy was arranged to 5, 10 and 25 mJ, where average laser power is kept to 250 mW. The reaction kinetics of the laser-induced particle formation was observed using dispersive XAFS measurement. About half of Pd ions were reduced with 5 mJ pulsed laser irradiation. In contrast, all Pd ions were reduced with 25 mJ pulsed laser irradiation. The result elucidates that the laser photon contributes to the generation of Pd metals by the multi-photon process.
Shibata, Takuya; Oba, Hironori; Seko, Noriaki*; Tagawa, Akihiro; Wakaida, Ikuo
no journal, ,