To examine the effect of the valence of iron in starting material, the composites were manufactured from iron (II) and (III) sulfates by sol-gel method. The obtained gel were calcinated from 700 to 1000°C, and Mössbauer spectra of composites were obtained. Mössbauer spectra showed that ε-Fe2O3 phase appeared in both composites. Iron (II) sulfate in the composites transformed to ε-Fe2O3 at lower calcination temperature than those of iron (III) sulfate, and that the content of ε-Fe2O3 phase appeared at higher temperature in composites prepared from iron (II) sulfate. Magnetization measurement supported the results derived by Möossbauer effect measurement.
We studied on the validity of combination of 210Pb concentration and sulfur isotope ratio of non-sea salt sulfate in aerosols as an index of long-range transported aerosols. As a result, it was found that multi-isotope method using 210Pb and δ34S was useful for long-range transported aerosols from the Asian continent.
Tritium monitoring using liquid scintillation method was summarized as part of environmental radioactivity monitoring programs by the prefectural governments in Japan which have nuclear facilities in their regions, was also described the current condition of the environmental tritium monitoring in Fukui prefecture.
In 1971, Aloka Co. Ltd. developed the world's first low background liquid scintillation counter for 100mL vials to measure the low level of 3H occurring in the nature, based on the characteristics of radiation measurement by the liquid scintillation method. Numerous performance enhancements, including low background technique for liquid scintillation counting have achieved by Hitachi Aloka Medical Co. Ltd. An overview of the enhancements and development of low background liquid scintillation counter are reviewed briefly.
he concentrations of 14C in the atmosphere are employed to check biomass fuels for their natural vegetation origin at present, because the vegetation is growing up by photosynthesis accompanying the fixation of carbon dioxide in the present atmosphere. Fossil fuels such as petroleum oil are free from the 14C. Bio Diesel Fuel(BDF) is vegetable origin attracting as a new alternative to diesel fuel from petroleum oil. Liquid scintillation counting system Quantulus 1220TM(LSC) is applied to the 14C measurement of BDF, as a direct measurement of the oil samples without any sample preparation. The Ultima Gold LLT was a good scintillator cocktail for the 14C measurement of the BDF. The 1g BDF sample mixed to the Ultima Gold LLT of 19mL showed evidently a good 14C βray spectrum. The 14C radioactivity of the BDF was consistent to the 14C concentration in the atmosphere at present time whereas the 14C in diesel oil of fossil fuel was negligible for the detection. The liquid scintillation counting method with low background is advantageous for the direct measurements of liquid samples without any sample preparation to the environmental radioactivity with a natural level.
Main target medias were seawater, river water, tap water and ambient samples and most of laboratories operated one liquid scintillation counter for measuring mainly 3H and 14C. Relationship between background count rate(B) and efficiency of counting(E) was observed in the distribution of the reported data, a few laboratories showing both lower background counting rate and higher efficiency, which indicates higher figure of merit derived by E2/B. Figure of merit ranged from 63 to 443. Since almost all the laboratories used commercially available standards, the comparability of the liquid scintillation measurements were ensured. Efforts to lower background counting rate were mainly carried out by counter manufactures.
Particle therapy using protons or carbon ions is capable of delivering high-dose radiation to tumors while minimizing the dose delivered to organs at risk because of its precise dose distribution. Furthermore, carbon ions show higher biological effects compared to photons. More than thirty particle therapy facilities are currently available in the world, but most of them are proton centers and only six centers can utilize carbon ions. In Japan, nine particle therapy facilities are in operation, five are under construction or determined to be constructed, and many are in the planning phase. In general, primary malignant tumors without metastases are good indications of particle therapy, such as skull base tumors, head and neck cancers, lung cancers, liver cancers, prostate cancer, postoperative recurrence of rectal cancer, and bone and soft tissue tumors. This form of therapy has recently been used to treat an increasing number of patients. We will discuss the overview of clinical outcomes of particle therapy in this article.