We present 28Mg imaging analysis in rice roots to study Mg uptake activity along the position of the root. The Mg uptake activity of 1mm root tip was relatively higher than those of the other parts. When the root was treated with aluminum, the Mg uptake activity was increased approximately twofold, suggesting that the increase of Mg uptake activity in root is one of the mechanisms of Al tolerance in a rice plant. The treatment with uncouplers (carbonyl cyanide m-chlorophenyl hydrazone and 2,4-dinitrophenol) and ATPase inhibitor (orthovanadate) showed the uniform decrease of Mg uptake activity in the root. On the other hand, the Mg uptake activity in the root tip was drastically reduced by hexaaminecobalt(III), an analog of hydrated Mg2+. The results suggest that hydrated Mg2+ is the dominant chemical form in Mg uptake in the root tip.
Electron absorbed fractions(AFs) and S values were evaluated in a voxel-based mouse phantom for preclinical evaluations of radiopharmaceuticals. The sources were considered monoenergetic in the electron energy range 10keV to 4MeV, and to be distributed uniformly with isotropic emission in the organs. The radiation transport was simulated using a Monte Carlo method. It was confirmed that electron AFs were dependent on the volume, density, and geometry of the source and target organs. The electron AFs for organ self-irradiation (i.e., the target is the source) decreased with increasing electron energy. The results from this study were consistent with other published data and indicated that the electron AF for self-irradiation was not always 1.0 and strongly depended on electron energy. The electron AFs for organ cross-fire (i.e., the target is not the source) were dependent on the electron energy emitted by the source and the geometries of source and target. Additionally, S values in the major organs of the voxel-based mouse phantom were tabulated for 131I, 153Sm, 188Re, and 90Y using the photon and electron AFs. The results of this study will be useful in determining organ doses in mice for radiopharmaceutical development.
The film dose distribution method is used for profile measurements of non-physical wedges, because three-dimensional automatic control water phantoms cannot be used. Recently, many hospitals have adopted computed radiography(CR) systems in preference to automatic developing processors and films. This may allow use of automatic processors to be discontinued. In this study, a beam was irradiated to an Imaging Plate(IP), and then IP was exposed to a fixed amount of light with fading, and we then measured the off-center ratio(OCR) absorbed dose distribution in external radiation therapy with non-physical wedge. This was compared with the OCR measured with an ionization chamber dosimeter. It was consequently possible for IP to approximate the value measured by the ionization chamber dosimeter by using a metal filter. This method offers a simple quality assurance technique for absorbed dose distribution in external radiation therapy with non-physical wedges in consideration of the character of the IP.
A number of dose rate data taken after the Fukushima Daiichi reactor accident occurred have been collected through official websites of prefectural governments. Subtracting natural background dose rates from these data, contributions due to fallout alone were evaluated. A train-borne survey was carried out to verify the accuracy of the contour map. The dose rate variation pattern obtained by the survey coincided fairly well with that of the map.
In this third part, discussion is focused on the undiscovered particles and the future development of particle physics, while preceding two parts concerned the elementary particles that had been already uncovered. The most promising framework that leads to new particles would be supersymmetry, and the possibility of its imminent discovery is introduced. Also, the relation between elementary particles and cosmic physics such as Dark Matter Problem is briefly mentioned.