Decomposition of fatty acid hydroperoxide is found to be proportional to the radiation dose. A dose of 20 kGy was found to decompose the hydroperoxide by 98%. Addition of phenolic antioxidants at 4.5 mM could not prevent the decomposition at 20 kGy but the phenolic antioxidants at 20 mM prevented the decomposition.
Concentrations of40K, thorium and uranium contained in the front glass of CRT (cathode ray tube) of television sets are measured by the γ-ray spectrometry. Although the obtained concentrations of thorium and uranium show the difference more than twice as much depending on the manufacturers, those of40K are almost equal for all CRTs. The dose rates are estimated for the CRT. Even the dose rate for the highest concentration of thorium and uranium is smaller than about one-tenth of that for the background radiations. It is practically negligible at a distance larger than 20 cm from the surface of the front glass of CRT.
A temporal increase in the atmospheric concentration of210Pb was observed in December, 1991, and January, 1992, at Seoul, the Republic of Korea. This increase was estimated to be due to the fallout of the stratospheric210Pb originating from the 1991 eruption of Pinatubo volcano, Philippines, along with the aerosol particles injected into the stratosphere by the eruption. The present observation was similar to the previous observations made at Tsukuba Science City, Japan.
Experiment on the effect of tooth position in oral cavity for various irradiation geometries was performed by using a human head phantom containing 32 permanent teeth. The head phantom was connected with the upper part of Rando phantom and irradiated by60Co gamma-rays with anteroposterior (AP), posteroanterior (PA) and right lateral (RLAT) geometries. Exposure for AP geometry was about 1290×10-4C/kg (500 R) at the labial side of upper central incisors, while for PA and RLAT geometries the phantom was turned by 180 and 90 degrees, respectively, and irradiated for the same period of time as for AP geometry. Although an established trend on the whole was found, correlation between dose of tooth enamel and its location in the oral cavity was not strong at least for high energy gamma-rays from60Co (average 1.25 MeV) .