RADIOISOTOPES
Online ISSN : 1884-4111
Print ISSN : 0033-8303
ISSN-L : 0033-8303
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Volume 58, Issue 1
Displaying 1-5 of 5 articles from this issue
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Articles
  • A Study of Degradation Mechanism of Alginate by Gamma-irradiation
    Le Quang LUAN, Naotsugu NAGASAWA, Vo Thi Thu HA, Tomoko M. NAKANISHI
    2009 Volume 58 Issue 1 Pages 1-11
    Published: 2009
    Released on J-STAGE: January 29, 2009
    DOIhttps://doi.org/10.3769/radioisotopes.58.1
    JOURNAL OPEN ACCESS
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    Alginate of an average molecular weight(Mw) of approx. 900kDa with the ratio of M(mannuronate)/G(guluronate)about 1.3 in aqueous solution was irradiated with 60Co gamma-rays at doses up to 800kGy. With the increase of the irradiation dose Mw of irradiated products was reduced and the dose was correlated with the molecular weight distribution of degraded products. The new bands appeared at 265 nm and 1709cm-1 in UV and FTIR spectra of irradiated alginate suggested that the scission was accompanied by side reactions leading to the formation of carbonyl groups. The chemical analysis proved the increase of carboxyl groups and reduction of reducing groups of irradiated alginate. The NMR spectra indicated not only the formation of carbonyl groups but also the generation of unsaturated product with C1 and C4 double bonds at nonreducing terminal and reducing end product. The degradation mechanism of alginate by irradiation was proposed.
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  • 238U-230Th-226Ra Radioactive Disequilibria in the Lava Flows of the 1986 Eruption from Izu-Oshima Volcano, Japan
    Yuichi KURIHARA, Masaomi TAKAHASHI, Jun SATO
    2009 Volume 58 Issue 1 Pages 13-24
    Published: 2009
    Released on J-STAGE: January 29, 2009
    DOIhttps://doi.org/10.3769/radioisotopes.58.13
    JOURNAL OPEN ACCESS
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    Time scale of magmatic processes in the 1986 eruptive activity of Izu-Oshima volcano, Japan, was estimated by the 238U-230Th-226Ra disequilibria observed in the 1986 lava flows. The activity ratios of 226Ra/230Th in the products were larger than unity, being enriched in 226Ra relative to 230Th. The 226Ra/230Th activity ratio versus 238U/230Th activity ratio and Ba/Th concentration ratio diagrams for the 1986 products showed positive correlations, suggesting that the 238U-230Th-226Ra disequilibria occurred during the magma genesis of Izu-Oshima volcano by the additions of U- and Ra-(Ba-)rich fluids derived from the subducting slab by dehydration to the mantle wedge. The 230Th-226Ra disequilibria in the 1986 products suggested that the time scale from the magma genesis to the eruption, including the melting of the mantle wedge, magma storage and magmatic differentiation from basalt to basaltic andesite, was less than 8000years.
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Materials(Data)
  • Quantity and Economic Scale of Food Irradiation in the World
    Tamikazu KUME, Masakazu FURUTA, Setsuko TODORIKI, Naoki UENOYAMA, Yasu ...
    2009 Volume 58 Issue 1 Pages 25-35
    Published: 2009
    Released on J-STAGE: January 29, 2009
    DOIhttps://doi.org/10.3769/radioisotopes.58.25
    JOURNAL OPEN ACCESS
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    The status of food irradiation in the world in 2005 was studied using a questionnaire survey and direct interview. The total quantity and economic scale of irradiated foods in the world were estimated as 405000 tons and 1.61 trillion Japanese Yen(JPY), respectively. Processed foods totaled 183000 tons(45%) in Asia and Oceania, 116000 tons(29%) in the American region, 90000 tons(22%) in Africa and Ukraine, and 15000 tons(4%) in the EU. The economic scale, estimated using the price at retail stores converted to JPY using an IMF conversion table, was 1.07 trillion JPY(67%) in the American region, 309 billion JPY(19%) in Asia and Oceania, 181 billion JPY(11%) in Africa and Ukraine, and 50 billion JPY(3%) in the EU.
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  • Application of Return Period to Evaluation of Extreme Events of Gamma Ray Dose Rate Due to Precipitation
    Yayoi INOMATA, Yasuhito IGARASHI, Masaru CHIBA, Michio AOYAMA, Katsumi ...
    2009 Volume 58 Issue 1 Pages 37-42
    Published: 2009
    Released on J-STAGE: January 29, 2009
    DOIhttps://doi.org/10.3769/radioisotopes.58.37
    JOURNAL OPEN ACCESS
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    The concept of the return period, which is a recurrence interval for the establishment of criteria whether the high level of gamma (γ) ray dose rate is an unusual value, is very effective. In this study, estimation method of the return period is described with using two probability functions, the Hazen plot and the Gumbel distribution. The practical application and its procedures of return period how to judge an extremely high γ ray dose rate as an unusual value are plainly described.
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