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Volume 61, Issue 4
Displaying 1-6 of 6 articles from this issue
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Articles
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Kouhei TEJIMA, Katsuya SATOH, Kiyoko TAKEDA, Tadashi YOKOYAMA, Issay N ...2012 Volume 61 Issue 4 Pages 161-171
Published: 2012
Released on J-STAGE: April 28, 2012
JOURNAL OPEN ACCESSA biofertilizer is a substance that holds beneficial microorganisms for plant growth in a carrier material. γ-irradiation is expected to sterilize the carrier material without changing its physical and chemical properties. To demonstrate the effect of γ-sterilization, the survival of the nitrogen-fixing bacterium Bradyrhizobium japonicum was monitored to assess the shelf life of biofertilizers. As biofertilizer carriers, five kinds of typical Japanese soil-based materials were used in this study. Following the sterilization of carrier materials by γ-irradiation (50kGy) or autoclaving (121°C for 40min), B. japonicum strain USDA110 was inoculated into each material. The biofertilizer was packed into polyethylene bags and stored for 12 months at 4°C or 30°C. After storage, viable inoculants in the biofertilizer were enumerated. Results indicated that inoculant density after storage was greater than the initial density in biofertilizers made from sterilized carriers, whereas it decreased significantly in biofertilizers made from non-sterilized carriers. γ-sterilization was superior to autoclave sterilization in enhancing inoculant survival in some cases. Due to the stability of supply, the high sterilization effect with lower radiation doses, and the high performance in maintaining a suitable inoculant density, Japanese peat soil (Keto-tsuchi) seems best suited as a biofertilizer carrier for B. japonicum among the tested soil materials.View full abstractDownload PDF (1405K) -
Yuto NAGAO, Hajime SEITO, Yohei MOMOKI, Hirohisa KANEKO, Kazumichi NAK ...2012 Volume 61 Issue 4 Pages 173-177
Published: 2012
Released on J-STAGE: April 28, 2012
JOURNAL OPEN ACCESSApplications of alanine dosimeter are widen to dosimetry in space environment and so on. The effect of temperature during and after irradiation between 20°C and 80°C on the dose response of alanine dosimeters was investigated under low dose of about 10 - 20Gy and long time of about 100 hours irradiations. Differences in dose response to that irradiated at 20°C were within ±2% for irradiation temperature of 60°C or less, and ±5% at irradiation temperature of 80°C, although the response was nonlinear to dose and 5 - 8% lower than that calculated based on the irradiation temperature coefficient of +0.24%/°C which was previously reported for high dose range of 103 - 105Gy. The dose response decreased only for the storage temperatures of 40 - 80°C which were higher than the irradiation temperature of 20°C. When a stable component of the dose response under high irradiation temperature is estimated on the basis of the effect of storage temperature after irradiation taking into account the known irradiation temperature coefficient, dose evaluation using alanine dosimeter should be more accurate even suffering from combined temperature effects during and after irradiation.View full abstractDownload PDF (903K)
Technical Reports
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Masato NAKAYAMA, Yuka TOGASHI, Masanori HARA, Masao MATSUYAMA2012 Volume 61 Issue 4 Pages 179-183
Published: 2012
Released on J-STAGE: April 28, 2012
JOURNAL OPEN ACCESSThe characteristics of three liquid scintillation cocktails for measuring a tritiated water sample have been investigated because the scintillator used in Hydrogen Isotope Research Center, University of Toyama was stopped selling hastily. Ecoscint XR and Ultima Gold AB are promising candidate scintillators for a replacement of LumaSafe Plus. For the evaluation of the applicability of candidate scintillators, three kinds of tritiated water samples were prepared:tritiated water samples, an acid solution contained metallic ions, and a drain water sample from the radiation controlled area. Tritium activities measured by using Ecoscint XR agreed with those measured by using LumaSafe Plus within about 10% of experimental error. However, the deterioration of the counting efficiency by Ecoscint XR was observed during measurements of the acidic sample. On the other hand, Ultima Gold AB showed a similar characteristic with LumaSafe Plus, and no deterioration of counting efficiency was observed for measurements of acidic solution. Therefore, Ultima Gold AB is more suitable as a scintillator for our sample water.View full abstractDownload PDF (1232K) -
Etsuko FURUTA, Keiji KUSAMA2012 Volume 61 Issue 4 Pages 185-192
Published: 2012
Released on J-STAGE: April 28, 2012
JOURNAL OPEN ACCESSSince the accident at Fukushima Daiichi nuclear power plant, many people purchased hand-held dosimeters for radiation measurement. However, each dosimeter showed different measurement value with μSv/h unit in many cases. So it became a serious issue whether those dosimeters were reliable or not. Eleven kinds of commercial hand-held dosimeters were purchased and the descriptions of the catalogues were checked according to the instructions of JIS Z4333. Also radiation dose rate for sealed and unsealed radioactive sources were measured by them. Some of the GM-type hand-held dosimeters could not measure β-rays;though it was described “possible” in their catalogues. It was disclosed for the usage of the dosimeters that some useful data were not mentioned in their catalogues. Also, some proposals were mentioned for the manufacturers and/or selling agents of the dosimeters.View full abstractDownload PDF (2897K)
Review Articles
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Hideki NARIAI2012 Volume 61 Issue 4 Pages 193-207
Published: 2012
Released on J-STAGE: April 28, 2012
JOURNAL OPEN ACCESSA big earthquake attacked north-eastern Japan at 14:46 on March 11, 2011. After about 40 minutes to one hour from the first quake, large tsunami attacked the coast of Tohoku and Kanto area, resulting the disaster named as the Great East Japan Earthquake. The earthquake and tsunami caused the reactor accident with meltdown of the fuels for operating three reactors at Fukushima Daiichi Nuclear Power Station of the Tokyo Electric Power Co.(TEPCO). The radioactive materials were discharged in atmosphere. The residents around the Nuclear Power Station were evacuated. The activities for settlement of the accident started and many lessons were learned from the accident. Present paper reviews the sequence of the accident, the actions for the settlement of the accident conducted by the TEPCO, the Government, et al., the lessons learned and the actions for them, and finally author's impression for the fundamental cause of the accident.View full abstractDownload PDF (2617K)
Serial Lecture
Current Perspectives of Radiation Therapy
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Koji ONO, Minoru SUZUKI, Shinichiro MASUNAGA, Natsuko KONDO, Yoshinori ...2012 Volume 61 Issue 4 Pages 209-222
Published: 2012
Released on J-STAGE: April 28, 2012
JOURNAL OPEN ACCESSBNCT is a therapy which selectively destroys the cancer cells by high LET and short track range particles through 10B(n, α)7Li reaction. Their ranges of particle and 7Li nucleus are respectively 9μm and 4μm, and do not exceed the diameter of general cancer cell. For this reason, selective accumulation of 10B compound in tumor cell or tissue is necessary. The clinical study which started in the U.S.A. was continued by the researchers in Japan, and BNCT has entered into new era at the beginning of 21st century supported by the results of basic and clinical researches, especially those in the end of 1980s and 1990s. An area of clinical study has expanded from malignant brain tumor and malignant melanoma to recurrent H & N tumor after standard treatment, liver cancer with multiple lesions, malignant pleural mesothelioma, etc. For a long time, research reactor has been used as neutron source. But it is quite inconvenient as clinical facility because of heavy task for safety control and limited site for construction. To dissolve this problem, the accelerator for BNCT has been developed by Kyoto University Research Reactor Institute and Sumitomo Heavy Industries, Ltd. as a substitute of research reactor first in the world.View full abstractDownload PDF (2485K)
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