Authors:T. Nakanishi, M. Kusakabe, T. Aono, and M. Yamada
A technique to determine concentrations of 32P, 33P and 7Be in dissolved and particulate forms, in the upper ocean was developed. By using a large volume in situ filtration and concentration
system (LV-FiCS), several tons of seawater at different depths were filtered concurrently through two kinds of filters. The
dissolved radionuclides were concentrated onto adsorbents in the LV-FiCS. The radionuclides obtained were further purified
by precipitation and ion-exchange chromatography, and quantified by gamma-spectrometry and ultra-low level liquid scintillation
counter measurements. The technique was used with good results in a coastal area of Ibaraki, Japan.
Authors:T. Ohya, K. Tanoi, H. Iikura, H. Rai, and T. Nakanishi
To study the effect of rhizosphere pH condition on the cadmium uptake movement, 109Cd, was applied as a radioisotope tracer to a soybean plant grown in a water culture at pH 4.5 or pH 6.5. The distribution
of 109Cd in the soybean plant was observed radiographically with an imaging plate (IP). The amount of Cd transported from the root
to the upper part of the plant at pH 4.5 was approximately two times higher than that at pH 6.5. However, the movement of
Cd in the upper part of the plant was similar under both pH conditions. The distribution of Cd inside the internodes at pH
4.5 also showed similar pattern to that at pH 6.5, suggesting that once Cd reached to the vessel of the root, the movement
of Cd was not dependent on rhizosphere pH conditions.
Authors:Y. Yoshida, T. Nakazawa, H. Yoshikawa, and T. Nakanishi
A partition coefficient (λ) for Ra in gypsum was determined from coprecipitation experiment using oversaturation method. The λ-value derived for Ra was: λRa = 0.32±0.15. Saturation state was estimated with the initial concentration of Ca and SO42− in an experiment of the present study. Saturation index was calculated to be (0.49±0.02). This value was similar to those
corresponds to analogous case where slow precipitation rate was kept in coprecipitation experiment for Sr in gypsum. Therefore,
derived λ-value is thought to describe partition of Ra and Ca in solid phase and solution under an equilibrium condition without the
effect of kinetic of precipitation. Determined λ-value was compared with those of other alkaline elements in sulfate minerals. The derived λ-value is smaller than that of Ra in barite and is similar to those of Sr in gypsum. This trend agrees with mechanical understanding
for the size effect against partition coefficient.
Authors:K. Norisuye, K. Okamura, Y. Sohrin, H. Hasegawa, and T. Nakanishi
The present paper describes a new analytical method for determining the 240Pu/239Pu isotopic ratio and 238Pu/239+240Pu α -activity ratio in seawater, both of which are important parameters for determining Pu sources in the ocean. Plutonium
isotopes were preconcentrated from a large volume of seawater (4700-10800 liter) by solid phase extraction using MnO2-impregnated fibers and eluted into 3M HCl. After the elution, the Pu species of all oxidation states were converted to Pu(IV)
using NaNO2, purified by solvent extraction using thenoyltrifluoroacetone (TTA)-benzene, and concentrated in 5 ml of 0.2M HNO2. The 240Pu/239Pu and 238Pu/239+240Pu ratios in the 5-ml final solution were determined by inductively coupled plasma-mass spectrometry (ICP-MS) and α-spectrometry,
respectively. A pg level of Pu, which was a sufficiently large amount for the determination, was obtained by the solid phase
extraction. Through the redox conversion and solvent extraction, the Pu species, such as Pu(III), Pu(IV) and Pu(VI), were
collected at a high recovery of 96±2% (n=3) despite the presence of large amounts of Mn, and interfering 238U (3.3 µg. l-1in seawater) was effectively removed with a decontamination factor of 1.7·107. The accuracy of the method for the 240Pu/239Pu ratio was verified using reference materials of seawater and a terrestrial soil sample. The present technique was applied
to the determination of the 240Pu/239Pu and 238Pu/239+240Pu ratios in coastal and oceanic water.
Authors:Y. Miyamoto, A. Kajikawa, J. Zaidi, T. Nakanishi, and K. Sakamoto
INAA, RNAA and IPAA were employed to determine upto 26 trace elements in 32 spices of 18 species and 16 pulses of 8 species originating from different localities. The results are compared with each other and the reported values. The concentration levels, their variations and the correlations of the analysed elements in these samples were also investigated. The variability of concentrations among the samples of different origin are small. The levels and ranges of the concentration are highly variable which are found to be characteristic to each element. High elemental correlations exist in some sets of elements, reflecting characteristics of chemical nature of elements and/or of their physiological functions.
Authors:S. Takai, T. Nakanishi, T. Tojo, H. Kawaji, T. Atake, and T. Esaka
Heat capacity measurements were carried out on Pb1-xLaxWO4+x/2 (x=0.2) and Pb1-xLa2x/3WO4 (x=0.2, 0.5) solid solutions prepared by sintering and mechanical alloying (MA) methods. For all the solid solutions, sintered
samples showed slightly larger heat capacity around 100 K in comparison with MA samples, which was presumably caused by the
excitation of mobile oxide ion motion. For sintered scheelite-type structured PbWO4s, high-temperature synthesis introduced oxide ion interstitials even for the Pb1-xLa2x/3WO4 system, which resulted in the excess heat capacity at low temperature for excitation. On the other hand, for the samples
prepared by room-temperature MA technique, oxide ion seemed to occupy the regular sites rather than interstitial ones and
excess heat capacities were not observed.
Authors:T. Saito, K. Tanoi, H. Matsue, H. Iikura, Y. Hamada, S. Seyama, S. Masuda, and T. Nakanishi
We present chemometric study to identify the provenance of agricultural product, beef. Combination of instrumental neutron
activation analysis (INAA) and prompt gamma-ray analysis (k0-PGA) were performed to determine 10 elements, C, H, N, S, Sm, Br, Mg, Na, K, Cl, nondestructively. We measured elemental
profiles in beef samples produced from different districts in Japan, Australia and USA. In the case of PGA, k0-method was employed to determine the elemental concentrations. There was a difference in elemental profiles between Japanese
black cattle beef and that produced in USA through principal component analysis (PCA). However, Holstein beef of Japan and
that of Australia was not sufficiently grouped by the PCA modeling with the elemental data set. This is the first study to
identify the provenance of beef through elemental analysis.
Authors:K. Sakamoto, N. Aota, Y. Miyamoto, S. Kosanda, Y. Oura, T. Okui, M. Igarashi, and T. Nakanishi
Fifteen GSJ (Geological Survey of Japan) and six KIER (Korean Institute of Energy and Resources; now Korean Institute of Geology, Mining and Materials, KIGAM) igneous rock series and nine GSJ sedimentary rock series reference samples were analysed for 21–29 elements by neutron and/or photon activation analysis (NAA and PAA); 14 MeV-NAA for Si and Al, fission track method for U, radiochemical and instrumental NAA for rare earth elements, with reactor neutrons for the latter two. Instrumental neutron and photon AA for the remaining elements were performed with reactor neutrons and bremsstrahlung of end-point energy of 30 MeV, respectively. The reactor irradiations were performed at core sites and also a thermal column of the Kyoto University Research Reactor. All of the radioassays were performed by -ray spectrometry with HPGe-detectors. The present results from the different types of irradiation are compared and discussed in terms of elemental abundances and rock types.
Authors:K. Takamiya, T. Inoue, K. Nakanishi, A. Yokoyama, N. Takahashi, T. Saito, H. Baba, and Y. Nakagome
In order to estimate the deformation rate of fission fragment at the scission point for thermal neutron-induced fission of233,235U and239Pu, double-velocity and double-energy measurements were carried out. As the result of the estimation of the deformation rate,
two types of scission point configurations were found. One type is composed of deformed light and heavy fragments, and the
other type is a combination of deformed light and spherical heavy fragments. Mass and total kinetic energy distributions were
sorted in two distributions by means of the type of configuration.