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Summary  

The behavior rhenium in surface seawater (0-30 m) was studied using the samples collected at three locations off the coast of Aomori Prefecture, Japan. The physico-chemical forms of Re in seawater from other locations were also studied to verify the Aomori findings. It was found that almost 100% of Re was in dissolved forms, mainly ReO4 -, therefore, the Re concentration was constant from the surface to 30 m depth and ranged from 6.1-7.4 ng. kg-1. The Re concentration in the Sea of Japan side was slightly lower than those in the Pacific Ocean side. Possibly, low Re concentration was added by river waters from Japan and/or the Asian continent to the Sea of Japan side.

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Abstract  

Use of an enriched156Dy isotope as an activable yield tracer for the determination of lanthanoid contents in various biological reference materials has been proposed. The method consists of preconcentration of the lanthanoid in the156Dy doped samples followed by neutron irradiation and further chemical purification steps. The chemical behaviour of lanthanoid elements in the whole procedure was found, in separate runs, similar to that of the added156Dy within experimental errors. Simple purification steps after irradiation allow the measurement of relatively short-lived nuclides and diminish the radiation dose received during the chemical treatment. The present results for orchard leaves (NBS SRM 1571) are generally in good agreement with the previously reported data. Some new data are obtained for other biological reference materials.

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Abstract  

The improvement obtained by epithermal neutron activation analysis was studied in terms of the detection sensitivity and precision in the γ-ray spectrometry for geological and biological reference samples. For geological samples, small improvement was observed only for the elements As, Ba, Sb, Se and U. For biological samples, however, large improvement was observed for As, Br, Sb and U. The ratio of the resonance integral to the effective thermal-neutron capture cross section was observed for 19 nuclides. The effect of the (n, p) reaction to the determination of Al and Mg by the ordinary reaktor-neutron activation analysis was estimated.

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Abstract  

Use of an enriched isotope as an activable tracer is proposed for the preconcentration of trace elements in neutron activation analysis. As a test of this method, contents of cadmium in various biological standard samples were determined by addition of an enriched116Cd tracer in the preconcentration step followed by neutron irradiation and -ray spectrometry. The principle, advantage, and limitations of the method are also discussed.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: K. Akiyama, H. Haba, K. Tsukada, M. Asai, A. Toyoshima, K. Sueki, Y. Nagame, and M. Katada

Abstract  

The properties of a metallofullerene that encapsulates 225Ac were studied by radio-chromatographic methods. The results of chromatography on a Buckyclutcher column suggest that there are some metallofullerene isomers of AcC82. The identical HPLC retention time of the major AcC82 peak with that of La@C82 indicates that the structure of one of the AcC82 isomers is the same as La@C82.

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Abstract  

Anion-exchange behavior of the group-5 elements, Nb and Ta, and their pseudo homologue Pa in HF and HF/HNO3 solutions was investigated by a batch method to find suitable conditions for the anion-exchange experiment of element 105 (Dubnium, Db). We determined the distribution coefficients of those elements on the anion-exchange resin as a function of the F and NO3 concentrations. Clearly different anion-exchange behavior was observed among these elements. Based on the results, we discuss the fluoro-complex formation of each element and suggest experimental conditions for the study of fluoride complexation of Db.

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Abstract  

The primary fragment mass-yield distribution for the asymmetric fission path in heavy nuclei, 233Pa, 239Np, 245Am and 249Bk at the excitation energy of ~20 MeV are experimentally constructed based on the intensities of total kinetic energies for individual mass splits. The results revealed an interesting phenomenon: in all the studied fissioning systems, the inner wings of the mass-yield distributions in the asymmetric fission path appear along the same mass-wall of A = 130 fragment mass. The asymmetric mass-yield distribution indicates the strong effect of structural shells in fragments on the final mass division process of the asymmetric fission path.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: K. Akiyama, K. Sueki, H. Haba, K. Tsukada, M. Asai, T. Yaita, Y. Nagame, K. Kikuchi, M. Katada, and H. Nakahara

Abstract  

We have, previously, reported on the HPLC elution behavior of the Th, Pa, U, Np, and Am metallofullerenes and the UV/vis/NIR absorption spectra of the Th@C84 and U@C82 species. In this paper, the followings are reported: (1) Pu metallofullerenes were produced and their HPLC elution behavior was investigated using a radiotracer technique. The HPLC chromatogram of this metallofullerene was found to be almost the same as that of the Np and Am metallofullerenes. (2) The oxidation states of Th@C84 and U@C82 produced in macroscopic quantities were examined by XANES (X-ray absorption near edge structure) measurements. The oxidation state of the U atom in the C82 fullerene cage was estimated to be 3+ with the formal charge of the ionic molecule being U3+@C82 3-.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: S. Mitsuoka, H. Ikezoe, T. Ikuta, S. Hamada, Y. Nagame, K. Tsukada, I. Nishinaka, and T. Ohtsuki

Abstract  

In order to separate rare fusion evaporation residues from the primary beam in flight, a recoil mass separator has been constructed at the JAERI tandem-booster facility. By using the recoil mass separator, new neutron-deficient isotopes209Th and212Pa have been produced. After a brief facility description, some recent experimental results are presented.

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