The food processing retention factor (Fr) is an important parameter to estimate radiation dose by food ingestion. Since rice is a staple food in Japan, we measured radiocaesium Fr for rice collected in 2011, which was contaminated with radiocaesium due to the accident at TEPCO's Fukushima Daiichi Nuclear Power Plant. Brown rice samples were polished at yield rates down to 82%, and at each yield rate, Fr was obtained. At a typical white rice polishing yield of 90 - 92%, the Fr value was 0.43 - 0.46. When the obtained white rice sample was washed, Fr decreased further to 0.27. Additional removal of radiocaesium is not expected by cooking (usually boiling) the rice, because the cooking temperature is not high enough to evaporate Cs. In rice bran samples, radiocaesium had the highest concentration in the middle layer;but in the same samples, the rice germ content was also high. Possibly because the radiocaesium concentration in the germ could be higher than that in the bran, apparent radiocaesium concentration in the middle layer was high.
Radon inhalation activates antioxidative functions in some organs of mice. We examined the prevention effects of pre radon inhalation and the alleviation effects of post radon inhalation on carbon tetrachloride (CCl4)-induced oxidative damage in the brain, heart, lung, liver, and kidney of mice. In addition, we compared the effect of pre and post radon inhalation on oxidative damage. Mice inhaled radon at a concentration of 18000Bq/m3 for 6hrs before or after CCl4 administration. As a result, the total glutathione(t-GSH) contents and catalase(CAT) activities in the brain, heart, lung, liver, and kidney and superoxide dismutase(SOD) activities in the heart and lung were significantly higher in pre and post radon-inhaled mice than in mice treated with only CCl4. Pre radon inhalation inhibited and post radon inhalation reduced lipid peroxidation induced by CCl4. In addition, there were no significant differences in lipid peroxide(LPO) levels in the brain, heart, lung, liver, and kidney between pre and post radon-inhaled mice. These findings suggested that post radon inhalation has the same effects as pre radon inhalation against CCl4-induced oxidative damage in the brain, heart, lung, liver, and kidney.
For a practice of a safety operating of a X-ray diffraction equipment (XRD) at a lecture room, not a controlled area, a commercial XRD was altered by RIGAKU Co., Ltd. A shielded acryl window was installed on the top, and a cable was passed through the back to measure dose inside the equipment. In practice, X-ray irradiated area emitted by the luminescence from a X-ray phosphor sheet were observed. A dose value of 5000μSv for 12's irradiation was observed as a maximum around a sample holder. Scattered X-rays from a glass plate set in the sample holder were able to observe using an X-ray detector. The interlock system was certified using the X-ray detector, slightly turning the knob of the door left to 45° to become 0V of the indication value of the detector. Finally, 88% of the attendance evaluated to be good and excellent for the practice.
Determination of human urinary metabolites after oral administration of 13C-labeled theophylline (TP) was examined by 13C-NMR spectroscopy. 13C-labeled TP(1,7-dimethyl-13C2-xanthine)was administered at a dose of 50mg to 5male volunteers who have normal hepatic and renal functions. Urinary samples were prepared by solid phase extraction with Sep-Pac Vac RC columns. NMR spectra of the urinary extracts indicated the specific resonances signals of unchanged TP and its main metabolites, 1, 3-dimethyluric acid(13U), 3-methylxanthine(3X) and 1-methyluric acid(1U). The integral signal intensity ratio of authentic 13C-labeled metabolites to [3-methyl-13C] caffeine(3-13C-CF) as an internal standard was directly proportional to the molar ratio of the compounds. Similar relationship was expected to other metabolites. From the results of quantification of urinary metabolites of 13C-labeled TP, remarkable individual difference was observed in the urinary excretion of metabolites between smoker and nonsmoker due to influence of hepatic CYP1A2 activity. In drug metabolism study, 13C-NMR spectroscopy with 13C-tracer was useful technique for detection and quantification of the metabolites.
The year's first crop of tea in Kanagawa Prefecture was contaminated with radioactive caesium derived from the Fukushima Daiichi nuclear power plant accident due to the East Japan earthquake disaster on March 11, 2011. In the present study, we investigated the distribution of radioactive caesium in the tea plants and examined how to eliminate radioactive caesium from them. The results obtained were as follows: 1)The radioactive caesium concentration(134Cs+137Cs)was 207Bq/kg in the first crop of tea leaves, was 650 - 800Bq/kg in old leaves, twigs and branches and it was 11 - 51Bq/kg in roots and trunks. 2)Radioactive caesium concentration in regenerated new shoots was reduced to 95Bq/kg by pruning after plucking. However, no change in the radioactive caesium concentration was observed in the second crop of tea leaves without pruning after plucking. 3)These results suggested that the radioactive caesium was fallout on old leaves, twigs and branches, absorbed into the tea plant and then translocated to the new shoots and that reduction of radioactive caesium in regenerated new shoots can be made possible by cutting off the contaminated old leaves, twigs and branches.
Radionuclides have been released to the environment from several sources, e.g., nuclear weapons testing and discharges from nuclear facilities. Mathematical models have been used for assessment of potential exposures to humans from released radionuclides. In the models, intake of foods is one of the important pathways, and thus, the mechanisms of radionuclide transfer to crops from environmental media (air, water, soil) are of interest. The mechanisms can be also applicable to all types of higher plants (wood and herbaceous plants) thus the topic is extended to plants. There are two main transport pathways to plant, i.e. direct deposition to plant surface and root uptake from soil. When plants absorb radionuclides, Cs could be translocated to other parts of plants, while Sr, Zn, Pu and Am were less mobile and remained at the absorbed area of the plant. After the releases of radionuclides to the air are ceased, the main radionuclide transfer pathway is root uptake. The uptake is controlled by a combination of several environmental and plant physiological factors;if the soil fixes a radionuclide then the uptake by root is not high, and if the radionuclide is a non-essential element, then the amount of root uptake is limited. Once Cs is absorbed by woody plants, Cs is partially removed when leaves are off from the trees, but a part of Cs remained in the wood body which can cause Cs contamination in newly emerged parts in the following growing season.
Neutron beam is one of important tools to obtain the transmission image of an object. Until now, steady state neutron sources such as reactors are mainly used for this imaging purpose. Recently, it has been demonstrated that pulsed neutron imaging based on accelerator neutron sources can provide a real-space distribution of physical information of materials such as crystallographic structure, element, temperature, hydrogen bound state, magnetic field and so on, by analyzing wavelength dependent transmission spectrum, which information cannot be observed or difficult to obtain with a traditional imaging method using steady state neutrons. Here, characteristics of the pulsed neutron source and principle of the pulsed neutron imaging are explained as a basic concept of the new method.