Fujiia Y.,Tokyo Institute of Technology |
Fujiia Y.,ATOX Co. |
Kima S.-H.,Tokyo Institute of Technology |
Kima S.-H.,Daegu Technopark Nano Convergence Practical Application Center |
And 2 more authors.
Zeitschrift fur Naturforschung - Section C Journal of Biosciences
A one hundred meter long ion-exchange chromatograph was used to establish rigorously the mass effects in the iron isotope fractionation in the Fe(II)-Fe(III) electron exchange equilibration.We used a highly porous, strongly basic anion exchange resin packed in glass columns. The abundance ratios of all natural iron isotopes, 54Fe, 56Fe, 57Fe, and 58Fe, in the effluent at the iron adsorption band boundary were measured with a mass spectrometer. The enrichment correlations among these isotopes were analyzed by three-isotope plots. The results clearly showed that the isotope fractionation of Fe(II)-Fe(III) is governed by the normal mass effect; the iron isotope fractionation is not proportional to the nuclear size, but proportional to the reduced mass difference of the pair of iron isotopes. © 2013 Verlag der Zeitschrift für Naturforschung, Tübingen. Source
Fujii Y.,ATOX Co. |
Nomura M.,Tokyo Institute of Technology |
Kaneshiki T.,Tokyo Institute of Technology |
Sakuma Y.,Tokyo Institute of Technology |
And 3 more authors.
Isotopes in Environmental and Health Studies
Benzo 18-crown-6-ether resin was synthesised by the phenol condensation polymerisation process in porous silica beads, of which particle diameter was ca 60μ Calcium adsorption chromatography was performed with the synthesised resin packed in a glass column. The effluent was sampled in fractions, and the isotopic abundance ratios of 42Ca, 43Ca, 44Ca, and 48Ca against 40Ca were measured by a thermo-ionisation mass spectrometer. The enrichment of heavier calcium isotopes was observed at the front boundary of calcium adsorption chromatogram. The mass dependence of mutual separation of calcium isotopes was analysed by using the three-isotope-plots method. The slopes of three-isotope-plots indicate the relative values of mutual separation coefficients for concerned isotopic pairs. The results have shown the normal mass dependence; isotope fractionation is proportional to the reduced mass difference, (M - M')/MM', where M and M' are masses of heavy and light isotope, respectively. The mass dependence clarifies that the isotope fractionations are originated from molecular vibration. The observed separation coefficient ε is 3.1×10-3 for the pair of 40Ca and 48Ca. Productivity of enriched 48Ca by crown-ether-resin was discussed as the function of the separation coefficient and the height equivalent to the theoretical plate. © 2010 Taylor & Francis. Source
Sakamoto F.,Japan Atomic Energy Agency |
Ohnuki T.,Japan Atomic Energy Agency |
Kozai N.,Japan Atomic Energy Agency |
Yamasaki S.,Japan Atomic Energy Agency |
And 2 more authors.
Transactions of the Atomic Energy Society of Japan
The local area distribution and relocation of radioactive cesium deposited in trees after the 2011 tsunami-related accident at the Fukushima Daiichi Nuclear Power Plant (FDNPP) have been studied by measuring the spatial distribution of cesium on/in trees by autoradiography analysis. Samples of trees were collected from places located between 4 and 55 km from FDNPP approximately 2, 8, 20, and 22 months after the accident. The autoradiography analyses of Cryptomeria japonica, Torreya nucifera, and Thujopsis dolabrata var. hondae samples collected approximately 2 and 8 months after the accident showed that radioactive Cs was mainly distributed as spots on the branches and leaves of the trees emerged before the accident, and was detected in negligible amounts in new branch and leaves that emerged after the accident. On the contrary, radioactive Cs was detected at the outermost tip of the branches in the trees collected 20 months after the accident. Morus alba samples collected 22 months after the accident contained radioactive Cs inside and outside their stems, even though no radioactive Cs was detected in their roots, strongly suggesting that a certain amount of radioactive Cs was translocated from the outside to the inside of stems. These results indicate that the distribution of radioactive Cs deposited on/in the trees gradually changes with time (scale: year). © 2013 Atomic Energy Society of Japan, All Rights Reserved. Source
Suto Y.,Japan National Institute of Radiological Sciences |
Hirai M.,Japan National Institute of Radiological Sciences |
Akiyama M.,Japan National Institute of Radiological Sciences |
Yuki M.,Tokyo Nuclear Services Co. |
And 6 more authors.
Among radiation-induced chromosome aberrations, multicentric chromosomes, as represented by dicentric chromosomes (dicentrics), are regarded as sensitive and specific biomarkers for assessing radiation dose in the 0 to 5 Gy range. The objective of this study was to characterize chromosome aberrations induced in vitro by a higher dose of radiation. Peripheral blood lymphocytes were exposed to 15 Gy gamma rays at a dose rate of 0.5 Gy/min and harvested at 48, 50, 52, 54, 56 and 72 h. The first mitotic peak appeared at 52-54 h, showing about a 6 h mitotic delay as compared with nonirradiated control cultures. Cell-cycle analysis of parallel and simultaneous cultures by sister-chromatid differentiation staining suggests that metaphase cells examined in 48-56 h cultures were in the first mitosis after culture initiation. The mean dicentric equivalent counts ranged from 9.0 to 9.3 in consecutively harvested cultures with no significant differences among them. At 72 h, about 20% of dividing cells were tetraploid, persisting with faithfully replicated unstable chromosome aberrations. The non-random distribution of replicated chromosome pairs, deduced from multicolor fluorescence in situ hybridization analysis, led us to surmise that the predominant mechanism underlying the induction of tetraploid cells is endoreduplication. These findings suggest that a high-dose in vitro irradiation applied to peripheral blood lymphocytes may affect on the replication process, in addition to structural chromosome damage. © 2012 The Japan Mendel Society. Source
Takeishi T.,Kyushu University |
Kotoh K.,Kyushu University |
Kawabata Y.,Kyushu University |
Tanaka J.-I.,Kyushu University |
And 2 more authors.
Fusion Science and Technology
In the decommissioning project of tritium handling laboratories or/and facilities, oils such as used in the vacuum pumps have been left conventionally in their comprehensive facilities. Existence of oils, especially highly-contaminated with tritium, is becoming one of the serious problems in projects for decommissioning tritium handling laboratories because of no disposal way of the tritiated waste oils. Experiments using bubblers were carried out to examine the tritium contamination and decontamination of a volume of rotary-vacuum-pump-oil. Contamination of pump oil was observed by bubbling with tritiated water vapor and tritiated hydrogen gas. And then, subsequent decontamination of tritiated oil was processed by bubbling with pure water vapor and dry argon gas. The bubbling with water vapor was more effective than with the dry gas. Experimental results show that the water vapor bubbling in an oil bottle can remove tritium efficiently from the contaminated oil into another water-bubbling bottle. © 2015, American Nuclear Society. All rights reserved. Source