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Journal Articles

Quantitative micro-X-ray fluorescence scanning spectroscopy of wet sediment based on the X-ray absorption and emission theories; Its application to freshwater lake sedimentary sequences

Katsuta, Nagayoshi*; Takano, Masao*; Sano, Naomi; Tani, Yukinori*; Ochiai, Shinya*; Naito, Sayuri*; Murakami, Takuma*; Niwa, Masakazu; Kawakami, Shinichi*

Sedimentology, 66(6), p.2490 - 2510, 2019/10

 Times Cited Count:2 Percentile:30.17(Geology)

Micro-X-ray fluorescence (XRF) scanning spectroscopy of marine and lake sedimentary sequences can provide detailed paleoenvironmental records available through element intensities proxy data. However, problems for effects of interstitial pore water on the micro-XRF intensities have been pointed out so far because of direct measurement on the split wet sediment surfaces. In this study, new methods for the XRF corrections were developed by being considered with the micro-X-ray scanning spectroscopy.

Journal Articles

Hydrological and climate changes in southeast Siberia over the last 33 kyr

Katsuta, Nagayoshi*; Ikeda, Hisashi*; Shibata, Kenji*; Kokubu, Yoko; Murakami, Takuma*; Tani, Yukinori*; Takano, Masao*; Nakamura, Toshio*; Tanaka, Atsushi*; Naito, Sayuri*; et al.

Global and Planetary Change, 164, p.11 - 26, 2018/05

 Times Cited Count:8 Percentile:48.18(Geography, Physical)

Paleoenvironmental and paleoclimate changes in Siberia were reconstructed by continuous, high-resolution records of chemical compositions from a sediment core retrieved from the Buguldeika Saddle, Lake Baikal, dating back to the last 33 cal. ka BP. The Holocene climate followed by a shift at ca. 6.5 cal. ka BP toward warm and dry, suggesting that the climate system transition from the glacial to interglacial state occurred. In the last glacial period, the deposition of carbonate mud from the Primorsky Range was associated with Heinrich events (H3 and H1) and the Selenga River inflow was caused by meltwater of mountain glaciers in the Khamar-Daban Range. The anoxic bottom-water during Allerod-Younger Dryas was probably a result of weakened ventilation associated with reduced Selenga River inflow and microbial decomposition of organic matters from the Primorsky Range. The rapid decline in precipitation during the early Holocene may have been a response to the 8.2 ka cooling event.

Journal Articles

Characteristics and formation process of fractures in crystalline rocks in northern Kyushu

Murakami, Hiroaki; Ashizawa, Masaomi*; Tanaka, Kazuhiro*

Oyo Chishitsu, 59(1), p.2 - 12, 2018/04

This study describes the features of fractures and their fillings along with the long-term behavior of their hydrogeological structures in an underground environment based on the results of a geological investigation conducted at an underground facility in northern Kyushu. Fractures were classified into five groups on the basis of fracture orientation: A, B, C, D, and low-angle groups. The genesis of all fractures is the cooling process of granodiorite pluton. Almost all of the water-conducting fractures are included in the B group. Because a number of fracture fillings in the B group are filled by prehnite and crushed fragments of epidote and quartz, the fractures in this group alternated sealing and re-opening. The fracture characteristics in the B group are follow as: accompanying many alteration halos, long trace length, and cutting off other fractures. These results indicate that fractures in the B group have possibly functioned as pathways for groundwater flow in the long term.

Journal Articles

Genetic changes in progeny of bystander human fibroblasts after microbeam irradiation with X-rays, protons or carbon ions; The Relevance to cancer risk

Autsavapromporn, N.*; Plante, I.*; Liu, C.*; Konishi, Teruaki*; Usami, Noriko*; Funayama, Tomoo; Azzam, E.*; Murakami, Takeshi*; Suzuki, Masao*

International Journal of Radiation Biology, 91(1), p.62 - 70, 2015/01

 Times Cited Count:28 Percentile:94.21(Biology)

Radiation-induced bystander effects have important implications in radiotherapy. Their persistence in normal cells may contribute to risk of health hazards, including cancer. This study investigates the role of radiation quality and gap junction intercellular communication (GJIC) in the propagation of harmful effects in progeny of bystander cells. Confluent human skin fibroblasts were exposed to microbeam radiations with different linear energy transfer (LET) by which 0.036$$sim$$0.4% of the cells were directly targeted by radiation. Following 20 population doublings, the cells were harvested and assayed for micronucleus formation, gene mutation and protein oxidation. The results showed that expression of stressful effects in the progeny of bystander cells is dependent on LET.

Journal Articles

Radiation-quality-dependent bystander effects induced by the microbeams with different radiation sources

Suzuki, Masao*; Autsavapromporn, N.*; Usami, Noriko*; Funayama, Tomoo; Plante, I.*; Yokota, Yuichiro; Muto, Yasuko*; Suzuki, Michiyo; Ikeda, Hiroko; Hattori, Yuya; et al.

Journal of Radiation Research, 55(Suppl.1), P. i54, 2014/03

Journal Articles

Experimental study for the production cross sections of positron emitters induced from $$^{12}$$C and $$^{16}$$O nuclei by low-energy proton beams

Akagi, Takashi*; Yagi, Masashi*; Yamashita, Tomohiro*; Murakami, Masao*; Yamakawa, Yoshiyuki*; Kitamura, Keiji*; Ogura, Koichi; Kondo, Kiminori; Kawanishi, Shunichi*

Radiation Measurements, 59, p.262 - 269, 2013/12

 Times Cited Count:11 Percentile:68.43(Nuclear Science & Technology)

In proton therapy, positron emitters are induced from $$^{12}$$C and$$^{16}$$O nuclei by protons on the beam path in the patient. Many studies for monitoring positron emitters with beam-induced PET technique have been performed by various groups to verify the proton beam range and the dose in the patient for quality assurance. The aim of this study was to develop a method for measuring the production cross sections of positron emitters using standard equipment for proton therapy. The time-activity curve was then obtained with a high-sensitivity PET scanner to extract the number of positron emitters produced in the target. The production cross sections for four reaction channels: $$^{16}$$O(p,pn)$$^{15}$$O, $$^{16}$$O(p,3p3n)$$^{11}$$C, $$^{16}$$O(p,2p2n)$$^{13}$$N, and $$^{12}$$C(p,pn)$$^{11}$$C were then measured. The cross sections for the $$^{16}$$O(p,pn)$$^{15}$$O reaction channel were consistent with data of previous experiments within the uncertainties, while those of $$^{12}$$C(p,pn)$$^{11}$$C were generally lower than data of previous experiments.

Journal Articles

Gap junction communication and the propagation of bystander effects induced by microbeam irradiation in human fibroblast cultures; The Impact of radiation quality

Autsavapromporn, N.*; Suzuki, Masao*; Funayama, Tomoo; Usami, Noriko*; Plante, I.*; Yokota, Yuichiro; Muto, Yasuko*; Ikeda, Hiroko; Kobayashi, Katsumi*; Kobayashi, Yasuhiko; et al.

Radiation Research, 180(4), p.367 - 375, 2013/10

 Times Cited Count:53 Percentile:90.3(Biology)

We investigated the role of gapjunction intercellular communication (GJIC) in the propagation of stressful effects in confluent normal human fibroblast cultures wherein only 0.036-0.144% of cells in the population were traversed by primary radiation tracks. Confluent cells were exposed to graded doses from X ray, carbon ion, neon ion or argon ion microbeams in the presence or absence of an inhibitor of GJIC. After 4 h incubation, the cells were assayed for micronucleus (MN) formation. Micronuclei were induced in a greater fraction of cells than expected based on the fraction of cells targeted by primary radiation, and the effect occurred in a dose-dependent manner with any of the radiation sources. Interestingly, the inhibition of GJIC depressed the enhancement of MN formation in bystander cells from cultures exposed to high-LET radiation but not low-LET radiation. The results highlight the important role of radiation quality and dose in the observed effects.

Journal Articles

Chemical forms of uranium, thorium and trace elements in sedimentary rocks distributed in Horonobe area, Hokkaido

Kosemura, Takashi*; Honda, Teruyuki*; Mizuno, Takashi; Murakami, Hiroaki; Nomura, Masao*

Fisshion, Torakku Nyusureta, (26), p.16 - 20, 2013/00

We Analyze existence form of REE in the rock from HDB-6 borehole at the Horonobe Town, Hokkaido. As a result, U and Th is mainly sulfate at fault. REE is mainly silicate at fault.

Journal Articles

Development of laser-driven quasi-monoenergetic proton beam line for radiobiology

Yogo, Akifumi; Maeda, Takuya; Hori, Toshihiko; Sakaki, Hironao; Ogura, Koichi; Nishiuchi, Mamiko; Sagisaka, Akito; Bolton, P.; Murakami, Masao*; Kawanishi, Shunichi; et al.

Nuclear Instruments and Methods in Physics Research A, 653(1), p.189 - 192, 2011/10

 Times Cited Count:9 Percentile:60.25(Instruments & Instrumentation)

Journal Articles

Radiobiology with laser-accelerated quasi-monoenergetic proton beams

Yogo, Akifumi; Maeda, Takuya*; Hori, Toshihiko*; Sakaki, Hironao; Ogura, Koichi; Nishiuchi, Mamiko; Sagisaka, Akito; Bolton, P.; Murakami, Masao*; Kawanishi, Shunichi*; et al.

Proceedings of SPIE Europe Optics + Optoelectronics 2011, Vol.8079, 8 Pages, 2011/04

Journal Articles

Measurement of relative biological effectiveness of protons in human cancer cells using a laser-driven quasimonoenergetic proton beamline

Yogo, Akifumi; Maeda, Takuya; Hori, Toshihiko; Sakaki, Hironao; Ogura, Koichi; Nishiuchi, Mamiko; Sagisaka, Akito; Kiriyama, Hiromitsu; Okada, Hajime; Kanazawa, Shuhei; et al.

Applied Physics Letters, 98(5), p.053701_1 - 053701_3, 2011/02

 Times Cited Count:90 Percentile:94.31(Physics, Applied)

Journal Articles

A Parameter study of pencil beam proton dose distributions for the treatment of ocular melanoma utilizing spot scanning

Sutherland, K.*; Miyajima, Satoshi*; Date, Hiroyuki*; Shirato, Hiroki*; Ishikawa, Masayori*; Murakami, Masao*; Yamagiwa, Mitsuru; Bolton, P.; Tajima, Toshiki

Radiological Physics and Technology, 3(1), p.16 - 22, 2010/01

Journal Articles

Application of laser-accelerated protons to the demonstration of DNA double-strand breaks in human cancer cells

Yogo, Akifumi; Sato, Katsutoshi; Nishikino, Masaharu; Mori, Michiaki; Teshima, Teruki*; Numasaki, Hodaka*; Murakami, Masao*; Demizu, Yusuke*; Akagi, Takashi*; Nagayama, Shinichi*; et al.

Applied Physics Letters, 94(18), p.181502_1 - 181502_3, 2009/05

 Times Cited Count:102 Percentile:94.73(Physics, Applied)

Journal Articles

Radiotherapy using a laser proton accelerator

Murakami, Masao*; Hishikawa, Yoshio*; Miyajima, Satoshi*; Okazaki, Yoshiko; Sutherland, K.*; Abe, Mitsuyuki*; Bulanov, S. V.; Daido, Hiroyuki; Esirkepov, T. Z.; Koga, J. K.; et al.

AIP Conference Proceedings 1024, p.275 - 300, 2008/08

no abstracts in English

Journal Articles

Super-parallel simulation systems for sophisticated radiation therapy

Saito, Kimiaki; Saito, Hidetoshi*; Kunieda, Etsuo*; Narita, Yuichiro*; Myojoyama, Atsushi*; Fujisaki, Tatsuya*; Kawase, Takatsugu*; Kaneko, Katsutaro*; Ozaki, Masahiro*; Deloar, H. M.*; et al.

Joho Shori, 48(10), p.1081 - 1088, 2007/10

no abstracts in English

JAEA Reports

Research and development for the high-temperature helium-leak detection system, 2; Development of temperature sensors using optical fibre for the HTTR (Joint research)

Sakaba, Nariaki; Nakazawa, Toshio; Kawasaki, Kozo; Urakami, Masao*; Saishu, Sadanori*

JAERI-Tech 2003-041, 106 Pages, 2003/03


In the second stage of the research and development for a high-temperature helium-leak detection system, the temperature sensor using optical fibres was studied. The sensor detects the helium leakage by the temperature inclease surrounded opitical fibre with or without heat insulator. Moreover, the applicability of high temperature equipments as the HTTR system was studied. With the sensor we detected 5.0-20.0 cm$$^{3}$$/s helium leakages within 60 minutes. Also it was possible to detect earlier when the leakage level is at 20.0 cm$$^{3}$$/s.

JAEA Reports

Research and development of a high-temperature helium-leak detection system, 1; Survey on leakage events and current leak detection technology (Joint research)

Sakaba, Nariaki; Nakazawa, Toshio; Kawasaki, Kozo; Urakami, Masao*; Saishu, Sadanori*

JAERI-Review 2002-041, 86 Pages, 2003/03


In High Temperature Gas-cooled Reactors (HTGR), the detection of leakage of helium at an early stage is very important for the safety and stability of operations. Since helium is a colourless gas, it is generally difficult to identify the location and the amount of leakage when very little leakage has occurred. The purpose of this R&D is to develop a helium-leak detection system for the high temperature environment appropriate to the HTTR. This system can shorten the time of detection to several hours from about one week in the current detection time. In addition, it can also identify easily the leak location using the optical fibre network. As the first step in the development, this paper describes the result of surveying leakage events at nuclear facilities inside and outside Japan and current gas leakage detection technology to adapt optical fibre detection technology to HTGRs.

JAEA Reports

Research and development for a high-temperature helium-leak detection system, 3; Development of radiation sensors (Joint research)

Sakaba, Nariaki; Nakazawa, Toshio; Kawasaki, Kozo; Urakami, Masao*; Saishu, Sadanori*

JAERI-Research 2003-006, 65 Pages, 2003/03


In the final third stage of the research and development for a high-temperature helium-leak detection system, the radiation sensor was developed in order to detect very small helium leakage. Applying the radiation sensor, we proposed not only the direct detection method which uses the detection of FP gas in helium, but also the active method which uses the difference in the radiation absorption between helium and air. From obtained data it was found that we can detect 0.2 cm$$^{3}$$/s leakage within 10 minutes by the active method.

JAEA Reports

Study on disposal method of graphite blocks and storage of spent fuel for modular gas-cooled reactor (Joint research)

Sumita, Junya; Sawa, Kazuhiro; Tsuchie, Yasuo*; Urakami, Masao*; Kunitomi, Kazuhiko

JAERI-Tech 2002-104, 23 Pages, 2003/02


This report describes the result of study on disposal method of graphite blocks in future block-type reactor. Present study was carried out within a framework of joint research, "Research of Modular High Temperature Gas-cooled Reactors (No. 3)", between Japan Atomic Energy Research Institute (JAERI) and the Japan Atomic Power Company (JAPCO), in 2000. In this study, activities in fuel and reflector graphite blocks were evaluated and were compared with the disposal limits defined as low-level of radioactive waste. As a result, it was found that the activity for only C-14 was higher than disposal limits for the low-level of radioactive waste and that the amount of air in the graphite is important to evaluate precisely of C-14 activity. In addition, spent fuels can be stored in air-cooled condition at least after two years cooling in the storage pool.

JAEA Reports

Development of a position-sensitive fission counter and measurement of neutron flux distributions

Yamagishi, Hideshi; Soyama, Kazuhiko; Kakuta, Tsunemi; Ochiai, Masaaki; Iwamura, Takamichi; Saishu, Sadanori*; Urakami, Masao*; Masuda, Naohiro*; Yamauchi, Yuki*; Otani, Junichi*; et al.

JAERI-Tech 2001-053, 19 Pages, 2001/08


no abstracts in English

40 (Records 1-20 displayed on this page)