Authors:I. Satoh, T. Watanabe, Y. Ishii, M. Kawasaki, and H. Suganuma
The stability constants (b1) of the monofluoro complex of Cm(III) have been determined in mixed solvents of methanol and water using the solvent extraction technique. The values of lnb1 increase as the molar fraction of methanol (Xs) in the mixed solvent increases. The variation in the stability constants mainly depends on the solvation of F- and slightly depends on both (1) the solvation of cations in connection with the complexation of CmF2+ and (2) the electrostatic attraction of Cm3+-F-. The variation in lnb1 for Cm(III) due to the effect of both (1) and (2) is similar to that for Sm(III). By variation of lnb1 the coordination number in the primary hydration sphere (CN) of Cm(III) decreased from a value between CN = 9 and CN = 8 to CN = 8, at about Xs = 0.02. The Xs value of the inflection point of the CN for Cm is slightly lower than Xs = 0.06 for Sm(III) and Xs = 0.03 for Eu(III), previously obtained.
Authors:M. Yoshida, S. Sumiya, H. Watanabe, and K. Tobita
A rapid separation method was developed for determination of low level promethium-147 and samarium-151. The rapid method, applied to environmental samples, provided speed and efficiency for the respective separation of Pm and Sm from other lanthanides with the simplified technique of high performance liquid chromatography (HPLC) system. The separation time of Pm and Sm in HPLC separation was shortened by stepwise eluent method of -hydroxyisobutyric acid as compared with a gradient eluent method of lactic acid with HPLC despite increase in sample volume for significant determination of Pm-147 and Sm-151. This method permitted the detection limit around 0.1 Bq/kg-dry-soil for Pm-147 and Sm-151 in 200 g soil sample by counting for 500 min with a liquid scintillation counter.
Authors:T. Kambara, J. Suzuki, H. Yoshioka, and Y. Watanabe
Radiometric titration of antimony(III) with potassium bromate in hydrochloric acid media using the standard series method
provided much valuable informations on the titration errors which depended on the concentrations of the acid and antimony(III).
The hydrochloric acid concentrations between 2.5 and 3.0M were found to be optimum for the oxidation of antimony(III) amounts
of 4 μg or less. Under these optimum reaction conditions the redox substoichiometric isotope dilution analysis was applied
to the determination of antimony in metallic zinc and the satisfactory results were obtained, without the separation of matrix
element. Also, the merits of various oxidizing agents hitherto studied for the quantitative oxidation of antimony(III) were
compared and discussed.
Authors:T. Watanabe, G. Zhang, H. Yoshida, and T. Kawai
The miscibility of crystalline syndiotactic polystyrene (SPS)/non-crystalline atactic polystyrene (APS) blend was estimated
by the crystallization dynamics method, which evaluated the nucleation rate, the crystal growth rate and the surface free
energy parameter. The melting temperature depression suggested that SPS/APS blends were the miscible system but not in molecular
level. The relationship between the blend content and the chemical potential difference evaluated at a constant crystal growth
rate showed a good linear relationship. These facts suggested that SPS/APS blends contained the concentration fluctuation
with the size between few nm to less than 80 nm.
Authors:M. Takeyasu, T. Iida, H. Watanabe, M. Takeishi, and A. Yamamoto
The performance of the computer code system, SIERRA-II, for calculating the environmental radiation dose due to an accident
was assessed over a coastal area, using the environmental monitoring data around the coastally located Tokai Reprocessing
Plant (TRP) when 85Kr was discharged during its operation. The agreement within a factor of 5 between the calculated and observed air concentrations
of 85Kr in areas of a few km from the TRP was achieved in 57% of the comparison data, disregarding the internal boundary layer.
The mean fraction bias was −0.6, which meant a slight overestimation. According to the vertical profile of the atmospheric
temperatures, the internal boundary layer was modeled with the SIERRA-II and the agreement became better than when the internal
boundary layer was not considered.
Authors:S. Watanabe, T. Katabuchi, N. Ishioka, S. Matsuhashi, and H. Muramatsu
Endohedral 133Xe-higher fullerenes (133Xe@C76 and 133Xe@C84) were produced by implantation of 133Xe ions using an isotope separator. A high performance liquid chromatography (HPLC) analysis showed that the peak of endohedral
133Xe-higher fullerenes shifted backward from that of empty fullerenes, suggesting a possibility of the separation of endohedral
133Xe-higher fullerenes from empty fullerenes. The yields of endohedral 133Xe-fullerenes were in the order of 133Xe@C76<133Xe@C84<133Xe@C60<133Xe@C70.
Authors:T. Tsuji, Y. Yamamura, H. Watanabe, K. Saito, and M. Sorai
The heat capacities and magnetic susceptibilities of powdered samples of FexNbS2 (x=0.14, 0.21 and 0.30) were measured at temperatures from 8 to 303 K and from 5 to 300 K, respectively. For Fe0.14NbS2, the magnetic susceptibility exhibited an anomaly as a shoulder at about 57 K, but no heat capacity anomaly was observed at this temperature, indicating the appearance of a spin-glass state. Anomalies in the heat capacity for FexNbS2 (x=0.21 and 0.30) occurred at 100.5 and 45.0 K, respectively, where the magnetic susceptibility displayed a maximum, corresponding to an antiferro-paramagnetic phase transition. The electronic state of the iron atom is discussed on the basis of entropy analysis.
Authors:R. Watanabe, T. Iyoda, T. Yamada, and H. Yoshida
Phase transition process of PEOm-b-PMA(Az)n was investigated
by the simultaneous DSC-XRD measurement using the synchrotron radiation facility.
Four endothermic DSC peaks were observed during heating process. These DSC
peaks were assigned to the melting of PEO, the transition from SmX, which
is a mixture of super-cooled SmC and crystal, to SmC, from SmC to SmA, and
from SmA to isotropic liquid state as determined by XRD profiles. In SmC phase,
the liner expansion coefficient calculated from the spacing variation of the
smectic layer distance was larger than that of the other phases. This result
reflected the fact azobenzene moieties in the long-side chains of PMA(Az)n
forming the smectic layers and then they were tilted and stood up during the
Authors:S. Watanabe, N. S. Ishioka, T. Sekine, H. Kudo, H. Shimomura, H. Muramatsu, and T. Kume
Hydrophilic endohedral 133Xe-fullerenols, [133Xe@C60(OH)xand 133Xe@C70(OH)x], were synthesized from hydrophobic endohedral 133Xe-fullerenes. The yield of endohedral 133Xe-fullerenols extracted in water was about 40% and 23% for C60and C70, respectively. The products stored in 0.9% NaCl solution at 20 °C were stable enough to be used in nuclear medicine.
Authors:M. Nakano, H. Watanabe, T. Shimizu, N. Miyagawa, S. Morita, H. Katagiri, and H. Ishiguro
The fire and explosion of the Bituminization Demonstration Facility at PNC Tokai Works were occurred on March 11th, 1997. As soon as the fire occurred, environmental monitoring was started. The influence of accidental release was recognized from some samples of airborne dust and surface soil on site. No influence was recognized from the samples off site except the airborne dust collected at O-arai (20 km south). The official statement by the Nuclear Safety Commission of Japan was: "It was less than the value which has an influence on the environment and health."