We updated our imaging system, namely real-time radioisotope imaging system (RRIS) to observe 32P movement in large plants using a large size scintillator. In the previous version of RRIS, the view was limited by the size of a CsI (Tl) scintillator deposited on a fiber optic plate (FOS). However, owing to the high price and difficulty in handling of FOS, the view area was limited to 100×200 mm. In this study, we evaluated 5 large and low-cost plastic scintillators and showed that plastic scintillators can be used in RRIS for the quantitative analysis of 32P. We also evaluated the resolution of the imaging system with plastic scintillator.
Radiocaesium (134Cs+137Cs) concentrations in surface air of Tsukuba (Ibaraki prefecture) and Iitate (Fukushima prefecture) about one year after Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident were levels of 10−5 Bq m−3 and 10−4 Bq m−3, respectively. The atmospheric radiocaesium at two sites of Iitate occasionally showed high concentrations due to resuspension of soil particles accompanied with strong wind and operation of local decontamination. A marked high concentration event on August 2013 seems to occur due to the removal of the debris at FDNPP. The activity median aerodynamic diameters of 134Cs- and 137Cs-bearing particles were larger than 1.2 µm. Radiocaesium-bearing aerosols with particle size of larger than 1 µm may partly be reached into the alveoli by respiration, although they will be excreted from lung thereafter. It is thought that the influence of annual internal radiation exposure by inhalation estimated from the atmospheric concentrations of radiocaesium was low.
The effects of low-dose rate/low-dose intrauterine exposure during organogenesis were investigated using pregnant mice and an experimental system employing both 2-D electrophoresis and mass spectrometry. Ras GTPase-activating protein-binding protein 1 and Rho GDP-dissociation inhibitor 1 are known to play vital roles in the morphological development of the nervous system such as synaptic plasticity and elongation of axons. These proteins showed a marked increase in fetal tissues collected 3 days after mothers were administered 3.7 MBq 33P-ATP. This suggests that active GTPase decreases and inactive GTPase increases resulting in a disruption of neurotransmission. To confirm if these changes were associated with microcephaly, PQBP1 (Polyglutamine binding protein 1) expression was determined by Western blot assay. Administration of 3.7 MBq resulted in a marked inhibition of PQBP1 expression in fetal tissues proving that even low-dose internal exposure was enough to induce changes suggestive of microcephaly. Actual measured values from the maternal injection site confirmed that the total dose over the 3 days after administration is about 50 mGy. This demonstrates that even low-dose intrauterine exposure warrants caution, suggesting that appropriate radiation safety measures such as education pertaining to the risks of exposure is important for pregnant workers.
We observed the distribution of 129I concentration off the Pacific coast in Aomori Prefecture from 2004 to 2007 and discussed the mean concentration of 129I in each water mass and origin of 129I concentration. The mean concentration of 129I in each water mass ranged from 14×106 to 19×106 atoms/L, which showed different between water masses. Considering global fallout level of 129I and amount of 129I produced by cosmic rays, 129I concentration in each water mass off the Pacific coast in Aomori Prefecture might be effected by the atmospheric release from European nuclear fuel reprocessing plants. The 129I concentration in each water mass seemed to reflect the differences in impact of westerly winds and air masses at the area that each water mass are formed.
This review describes the synthesis of iron-based nanoparticles. Iron oxyhydroxide, iron oxide, iron carbide, and iron sulfide nanoparticles have been produced using various methods. Feroxyhyte δ-FeOOH nanoparticles were produced by the oxidation of precipitates obtained by hydrazine reduction of iron chloride. Similar nanocomposites doped with foreign atoms (Ag, Cu, or Zn) have been produced as well. Iron oxide (γ-Fe2O3) nanoparticles have been produced by a polyol method. When a sulfide source was added into the solution during synthesis, iron sulfide nanoparticles were obtained. Using this technique, a metastable trivalent iron sulfide (Fe2S3) was successfully synthesized. Amorphous iron/carbon particles were obtained by the sonochemical synthesis of ferrocene in diphenylmethane. Subsequent heating of the amorphous particles produced Fe3C, α-Fe, and γ-Fe nanoparticles. Laser ablation of iron metal in an organic solvent produced iron carbide nanoparticles. The reaction mechanism and the structures of the nanoparticles were studied using Mössbauer spectroscopy as well as X-ray diffraction and transmission electron microscopy.