RADIOISOTOPES
Online ISSN : 1884-4111
Print ISSN : 0033-8303
ISSN-L : 0033-8303
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Volume 60, Issue 4
Displaying 1-4 of 4 articles from this issue
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Articles
  • A Rapid Detection for Irradiated Fresh Papayas Using ESR Spectroscopy
    Masahiro KIKUCHI, Yuhei SHIMOYAMA, Mitsuko UKAI, Yasuhiko KOBAYASHI
    2011 Volume 60 Issue 4 Pages 163-171
    Published: 2011
    Released on J-STAGE: April 28, 2011
    DOIhttps://doi.org/10.3769/radioisotopes.60.163
    JOURNAL OPEN ACCESS
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    The detections of radicals induced in irradiated both fresh and dried papayas were carried out at liquid nitrogen and room temperature using electron spin resonance (ESR) spectroscopy.
    Fresh papayas irradiated by the γ-rays were separated into flesh and skin that subjected to the ESR detection. The ESR spectra of the specimen at liquid-nitrogen temperature were observed clearly at a week after the γ-irradiation. Those signals were consisted from main peak at g=2.000 and side peaks at g=2.018 and 1.982. They showed a linear response against the dose. Furthermore, the side peaks from freeze-dried papaya flesh stored at 4°C were observed clearly at two weeks after the γ-irradiation. Those signals also showed the linear dose-response. The detection scheme for irradiated fresh fruits can be done by two stages:
    1) A screening test of ESR signals at liquid nitrogen temperature using fresh samples.
    2) A room temperature ESR measurement using freeze-dry samples.
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  • ESR Analysis of Irradiated Red Peppers and Commercial Red Peppers in Japan
    Hiromi KAMEYA, Mitsuko UKAI
    2011 Volume 60 Issue 4 Pages 173-180
    Published: 2011
    Released on J-STAGE: April 28, 2011
    DOIhttps://doi.org/10.3769/radioisotopes.60.173
    JOURNAL OPEN ACCESS
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    ESR analysis of γ-ray irradiated and being treated with different processing red pepper was studied. All the red peppers were commercial expect irradiated one. Processing treatment of red pepper was sun drying, mechanical processing(heating sterilization and powdering treatment). All the samples were weighted and analyzed. The ESR spectrum of the red pepper is composed of a singlet at g=2.00. This signal was originated from organic free radical. It is suggested the effect of heating treatment on the radical formation is not so large and powdering treatment will promote the radical formation of red pepper. ESR singlet signal of the irradiated red pepper showed the large signal intensity and the dose-dependence. The singlet signal intensity of irradiated powder sample showed the almost same value as compared with that of the powder sample with heating treatment. Relaxation times (T1 and T2) of the singlet signal were calculated. The relaxation behavior and relaxation times of the irradiated sample were different from that of the non-irradiated sample. The value of T1, the spin lattice relaxation time, of irradiated sample was increased and T2, the spin-spin relaxation time, of irradiated sample was decreased. We concluded that the radical formation of the red pepper is mainly depended on the powdering treatment and irradiation.
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  • Terrestrial Gamma Ray Dose Rates in Granitic Rock Terrains in Japan
    Susumu MINATO
    2011 Volume 60 Issue 4 Pages 181-187
    Published: 2011
    Released on J-STAGE: April 28, 2011
    DOIhttps://doi.org/10.3769/radioisotopes.60.181
    JOURNAL OPEN ACCESS
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    Air absorbed dose rates evaluated from uranium, thorium and potassium contents in rock samples (rock dose rate) have been compared with K2O data in order to understand lithologic characteristics of terrestrial γ-ray dose rate levels in granitic rock terrains. The comparison showed that the dose rate increased with increasing K2O content of rock. The crystallization differentiation model of magma was used to analyze this trend quantitatively. Next, data sets were compiled with respect to dose rate measured on soil (soil dose rate) and K2O content of bedrock at the corresponding site. A semi-empirical formula expressing the soil dose rate as a function of K2O content of rock was derived by comparing with the rock dose rate analysis.
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