As a quality control of 99mTc-labeled radiopharmaceuticals, a quick and convenient method of radiochemical purity(RCP) measurement were investigated. In this study, two methods to measure the RCP of 99mTc-hydroxymethylene diphosphonate(99mTc-HMDP) and 99mTc-human serum albumin(99mTc-HSA) were proposed. The RCP of 99mTc-HMDP was measured by thin-layer chromatography(TLC) using a mixture of 1M ammonium chloride, 1M carbamide, and acetic acid(70:28:2) as a solvent and a high-performance thin-layer chromatography cellulose plate. Development time taken by this method was a quarter of the time taken by the method using a mixture of 2M ammonium chloride, 10M carbamide, and acetic acid(49:49:2)as a solvent and a thin-layer cellulose chromatography plate without loss of measurement accuracy. The RCP of 99mTc-HSA was measured by paper chromatography using 100% acetone as the solvent. Development time taken by this method was one sixteenth of the time taken by the method using 75% methanol as a solvent without loss of measurement accuracy.
Multi-wire chambers are used in the field of elementary particle and nuclear physics. A new multi-wire chamber with the narrow anode wire pitch pa of 1mm has been constructed. The chamber has an anode wire plane and a grid wire plane in parallel. Also wire directions of both planes are mutually perpendicular in order to obtain 2-dimensional information. Main items on the design such as charge and electric field were calculated by analytical equations, not depending upon simulations by computers and some experiences. A new method called “modified charge division” for read out of signals has been developed. The signals were handled with only 4 pre-amplifiers. To confirm the properties of the chamber, we took a 2-dimensional image of a maple leaf as a sample by exposing to α particles out of an emitter 241Am. The chamber can be operated, even if the pitch pa is so narrow. A vivid picture was obtained on the screen by using the chamber which was designed due to a few analytical formulae.
After the emission of radioactive plumes from the Fukushima Daiichi Nuclear Power Plant in mid March, 2011, predominantly Cs nuclei have been responsible for radiation doses since June. The data of air dose rates at 155 points in central and eastern Fukushima prefecture acquired by the central and local governments through the period of June 10th and December 5th are analyzed to investigate their temporal and spatial variations. The calculated average rate of reduction is 22±2%, being twice as large as 11%, which is based on the radioactive decay process of 134Cs and 137Cs during the same period. Therefore, weathering effects are found comparable to those of radioactive decay. Owing to the strong weathering effects, the reduction rate of air dose rate tends to depend on the season. It is also found that some areas are still being contaminated through principally westward winds blowing from more contaminated areas like central-Namie and its vicinity.
Recent research developments are explained on the paleoenvironmnet, which is elucidated by the deep ice core analysis, and on the cryosphere changing due to the global warming. The 2503m and 3035m deep ice cores were drilled in Dome Fuji, Antarctica, and the glacial-interglacial cycles with the periodic air temperature variation of 20, 40 and 100 thousand years cycles were recognized clearly. Cryosphere changing are especially remarkable in the Northern Hemisphere. There are many scientific reports dealing with the sea ice extent decreasing in the Arctic sea, the mountain glacier retreat, and the permafrost degradation. We need the reliable data accumulation which serves as the basis of scientific discussions.
NRU in Canada and HFR in the Netherlands which had been producing the most important medical isotope, 99Mo, were shut down in 2009-2010. As the production of more than 95% of global 99Mo supply were performed in only five research reactors in the world including the two reactors mentioned above, these shutdowns resulted in global supply shortage of 99Mo. Although the medical isotope crisis were alleviated after the two reactors returning to service, all of these five 99Mo producing reactors are approximately 50 years old. Because the remaining life time of these reactors is not so long, the construction of new reactors or the development of new technologies to produce bulk 99Mo, such as the neutron activation of 98Mo in a reactor or charged particle reaction by accelerator, are proposed for the long-term security of supply of 99Mo. The methods using the molybdenum target lead to much lower specific activity of 99Mo compared to the production with fission method. The new chemical processing technologies, such as manufacturing 99mTc-labeled radiopharmaceuticals from such low specific activity 99Mo, are required for the development of domestic practical production of 99Mo.