The contents of iodine in the dry and wet laminaria collected from several local markets were found to be very close each other ranging from 2380 to 2510μg/g and 48.2 to 81.6μg/g, respectively. The contents of iodine remained in the solid part of laminaria either after being immersed in water or after being boiled in water for a long time were found to be the same around 60μg/g, although, by boiling, the leaching rate of iodine from the laminaria was more rapid than by immersing. The major component of iodine in the laminaria was apparently of the water solube species and was speculated to be an inorganic form, e.g., iodide. The fact of similar iodine content remaining in the laminaria after both treatments, with cold and boiling water, may tell that there is a particular iodine species bonded in the laminaria (ca. 2.5%) which can not be leached out by water. No loss of iodine by volatilization was observed during the leaching of laminaria even by boiling, since all the iodine leached out could be found in the waters.
It is expected that gamma (γ) and ultraviolet (UV) rays are applicable to sterilize agricultural products for reducing storage losses. In practical application, D10-and D99.9-value in γ and UV irradiation have been used as sterilization indices. However, our preliminary results showed that these survival curves were exponential having a shoulder at a beginning in many strains of molds. This suggests the difficulty in assessing a sterilization level accurately using these indices. The survival curves of several molds infecting agricultural products for γ irradiation were simulated with a multi hit theory in molecular radiation biology. On the other hand, the effect of UV irradiation on the survival curves was simulated by multi hit theory, taking into account the decrease in UV-intensity in liquid suspensions due to Lambert's law. It was found that the models based on a multi hit theory well simulated the effects of γ and UV irradiation. Among molds tried in this study, the four hits model best fit to the observed data in cases of Phycomycetes. These results demonstrated that D10-and L-values, instead of conventional indices based on D10-and D99.9-values, should be used to assess the sterilization level accurately. To obtain more reliable measurement, a target area and a hit number, a parameter of penetration in UV-sterilization should be taken into considerations.
Some glaze samples of cloisonne works, as one of the radioactive consumer products are studied. γ-Ray spectrum of the glaze measured by a high purity Ge detector shows peaks of γ-rays from234mPa, 234Paand234Thas well as235U.These glaze samples seem to be based on depleted uranium. The calculated radioactivity of uranium in 1g of glaze“extra gold”is 700 Bq. The results of dose equivalent measured by film badges prove that most of the dose is contributed by β-rays of uranium series elements and that the dose is independent of glaze thickness because of strong self-absorption of β-rays.