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Abstract  

Silver cationic clusters formed in γ-irradiated AgCs-rho zeolites in hydrated and dehydrated forms have been studied by electron spin resonance (ESR) spectroscopy and diffuse reflectance spectrophotometry. It was found that tetrameric silver clusters, Ag 4 3+ in dehydrated zeolites and Ag 4 2+ in hydrated samples, are stabilized at room temperature. Tetrameric silver is trapped inside octagonal prism of zeolite framework and does not show any noticeable decay as far as samples are evacuated.

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This study was aimed at elucidating numerical variation of chromosomes in newly synthesized hexaploid wheats. We carried out artificial crosses between Triticum carthlicum (2n = 4x = 28, AABB) as female parent and Aegilops tauschii (2n = 2x = 14, DD) as male parent, obtaining intergeneric F1 hybrids (2n = 3x = 21, ABD). After self-fertilization of the F1 hybrids having 21 somatic chromosomes, we obtained F2 seeds (synthetic hexaploid wheats), and determined their somatic chromosome number. Of the expected 150 cross combinations of F1 hybrids between six strains of T. carthlicum and 25 strains of Ae. tauschii, 67 cross combinations of synthetic hexaploid wheats were obtained. Compared to strains of Ae. tauschii ssp. tauschii, those of Ae. tauschii ssp. strangulata produced synthetic hexaploid wheats showing euploidy with a high frequency. In addition, among strains of Ae. tauchii ssp. tauschii, those from Iran contributed more to the production of synthetic hexaploid wheats showing euploidy than those from Afghanistan, Pakistan, Turkey or the former USSR.

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Abstract  

The UV photolysis of pentacarbonyliron isolated in low temperature nitrogen matrix was studied by the Mössbauer Technique. Besides stable compounds /Fe2/CO/9 and Fe3/CO/12/ unstable species such as Fe/Co/4 and Fe2/CO/8 were produced by UV irradiation. Furthermore, the unstable species were found to react with nitrogen matrix, leading to the formation of Fe/CO/4N2. Mössbauer parameters of the products were obtained.

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Abstract  

The state of dispersion and photochemical behaviour of tris/-diketonato/ iron/III/ complexes isolated in low temperature matrices were characterized by means of57Fe Mössbauer spectroscopy. Tris/acetylacetonato/iron/III/ iron/III/ molecules isolated in a nitrogen matrix were aggregated by photoexcitation. Photoreduction of tris/hexafluoroacetylacetonato/-iron/III/ in solid ethanol was also monitored by the Mössbauer technique.

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Abstract  

Mössbauer parameters of tin compounds, Sn(CH3)nCl4–n (n=0, 1, 2, 3, 4), isolated in low temperature matrices are correlated with electronic properties at the tin nuclei obtained by molecular orbital calculations. The Mössbauer isomer shift and quadrupole splitting show good correlation with electron density and electric field gradient estimated by molecular orbital calculations, respectively. Structures of novel species (Sn(CH3)2CH2 and [Sn(CH3)2CH2]2) produced via photodissociation of Sn(CH3)4 in low temperature matrices were estimated by means of molecular orbital calculations as compared with Mössbauer parameters.

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Summary  

From the viewpoint of environmental radioactivity monitoring, the determination of uranium and its isotope ratio is important for identifying and assessing the environmental impact of any unexpected release from nuclear facilities. In this work, a survey was conducted to determine 238U concentrations and 235U/238U atom ratios in coastal waters off Rokkasho Village, Aomori, Japan, where several uranium-related nuclear facilities have been operating since 1992, and a newly constructed nuclear fuel reprocessing plant is scheduled to be commissioned in 2006. Seawater samples were analyzed directly after a 10-fold dilution using isotope dilution sector-field ICP-MS. Based on the results, we concluded that there is no observable uranium contamination in the investigated sites. In addition, for the first time, a correlation between uranium concentration and salinity was established in coastal waters using the SF-ICP-MS technique.

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Abstract  

For Mössbauer -rays in the in-beam Mössbauer experiments using various beams such as heavy ion, secondary short-lived isotope, and neutron beams, it is important to develop a detector. A parallel-plate avalanche counter (PPAC) is the most suitable gas counter for on-line measurements, because PPAC collects the internal conversion electrons emitted by the Mössbauer effect even under high -background. We evaluated the influences of the pressure and flow rate of the counter gas against the counting efficiency of PPAC, and determined the optimum conditions for use in the in-beam Mössbauer experiments.

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Abstract  

Reaction mechanism of base hydrolysis of halobis/8-quinolinolato/oxotechnetium (V) /TcOX (ox)2 X=Cl and Br/ was investigated by means of solvent extraction and spectrophotometric methods. Furthermore, distribution coefficients of tris/acetylacetonato/technetium/III/, dichlorobis/8-quinolinolato/technetium/IV/ and TcOX/ox/2 between chloroform and aqueous solutions were determined. In an alkaline solution, TcOX/ox/2 decomposed to pertechnetate as a final product. On the basis of the established base hydrolysis, the respective rate constants were determined.

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Abstract  

An analytical method for the determination of 239Pu and 240Pu in marine particle samples by sector field high-resolution ICP-MS was developed. The method was applied for large and small particle samples (particle diameter: >70 μm and 1–70 μm, respectively, collected with a large volume in situ filtration and concentration system at different depths in the water column off Rokkaho, Japan, where the spent nuclear fuel reprocessing plant of Japan Nuclear Fuel Ltd. has started test operation since March 2006.

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Journal of Thermal Analysis and Calorimetry
Authors:
K. Moriya
,
T. Yamada
,
K. Sakai
,
S. Yano
,
S. Baluja
,
T. Matsuo
,
I. Pritz
, and
Y. Vysochanskii
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