In some tea tree planting areas within 300 km from the TEPCO’s Fukushima Daiichi Nuclear Power Plant (FNPP), it was found
that newly emerged tea plant leaves for green tea contained two radiocesium species (cesium-134 and cesium-137). In this study,
using processed green tea leaves for drinking, extraction ratios of radiocesium under several brew conditions were observed.
When 90 °C water was used, 50–70% of radiocesium was extracted into the water, while 54–60% of radiocesium was extracted with
60 °C water. A part of radiocesium would be removed from leaves if the leaves were washed with 20 and 60 °C water before brewing,
and the efficiencies were 11 and 32%, respectively. Newly emerged camellia leaves were used to simulate the radiocesium removal
ratio from raw tea leaves by washing and boiling; radioactivity concentration was decreased to 60% of the original concentration
with washing and 10 min boiling. From these results, it was found that almost half of the radiocesium would not be removed
from raw or processed tea leaves. The values obtained in the present study could be used for internal radiation dose estimation
from tea leaves.
Authors:M. Ishikawa, K. Kitao, H. Imaseki, T. Ishii, and S. Uchida
The resolution of a 33±3 m microprobe focussed with quadrupole doublet installed at the 3 MV Van de Graaff of the National Institute of Radiological Sciences was used for this analysis. Brown algae, Hijiki,Hizikia fusiforme was the sample target bombarded with a 2 MeV proton beam collimated mechanically into a rectangular image of 100 m × 700 m. Scanning across the sample target prepared into a longitudinal section from the caulis of the algae provided the following observations. More than 12 elements such as Al, Si, P, Cl, Ca, Mn, Fe, Cu, Zn, As, Br and Sr were determined simultaneously, together with their distributional information across the diameter. In the medullary layer, Mn and Zn were specific in their accumulation, while the deposition of Fe, Cu, As and Br were observed to be high in the epithelial layer, especially Fe and Cu which were found on the surface, where they contact ambient sea water, but no significant change in pattern was indicated for such elements as Al, P and Cl. The PIXE microprobe analysis was, therefore, effective in its detectability for elements below a few ppm level, resultantly provides further possibilities for collecting information from bio-medical and environmental samples on trace characterization of elements.
Authors:T. Chong, S. Kambe, H. Kawaji, T. Atake, and O. Ishii
In this study, GdBaSr(Cu3−xMx)O7−δ bulk samples (M=Zn and Ni; 0≤x≤0.1) were prepared via solid-state reaction. Specific heat measurement (measured with thermal relaxation technique using
PPMS) shows an obvious specific heat jump around the Tc for GdBaSrCu3O7−δ sample as observed in most of the high temperature superconductors. It shifts towards lower temperature with increasing of
both Zn and Ni doping contents, whose tendency is similar to the decreasing of Tc. Debye temperature, ΘD (derived from specific heat measurements) calculated at around 10 K is found to be directly proportional to the Tc.
Authors:T. Ishii, R. Furuichi, Y. Hara, and S. Shimada
Interesting effects of fluoride additives, LiF, NaF and CaF2, on the solid-state reactions in the MgO - Cr2O3 and ZnO - Cr2O3 systems under an atmosphere of nitrogen were observed by means of DTA. For the MgO Cr2O3 - MF (M=Li, Na) systems, it was concluded that the melting of the fluoride additives plays an important role in accelerating the second reaction step at around 1000°. On the other hand, for the ZnO- Cr2O3 - MF (M=Li, Na) systems, a great acceleration by the additives was observed in the first reaction step at around 700°, a much lower temperature than the melting points of the fluorides. The effect of CaF2 was not clear in either system.
Authors:K. Yanagisawa, H. Takeda, K. Miyamoto, S. Fuma, and N. Ishii
Tracer experiments on the transfer of carbon from culture solution to Daphnia magna through phytoplankton have been carried out using 13C and infrared absorption method. The purpose of this experiment is to investigate the experimental systems for the use of 13C in aquatic system. Daphnia magna was cultured in a 100 ml of solution containing phytoplankton and 20 mg of NaH13CO3 for 24 hours in the light and dark conditions (2000 lux, 14 hour light and 10 hours dark at 25 C). The concentration of 13C in Daphnia magna under light condition was about 2.0% (atom% excess), while in the dark condition 13C tracer was not detected. The concentration of 13C in phytoplankton under light condition was around 20%. It was suggested that 13C added as carbonate in the culture solution was photosynthetically assimilated by phytoplankton and then transferred to Daphnia magna. Using this system, the effect of UV-B exposure on the 13C uptake of Daphnia magna has been examined. The UV-B intensity was 95 mW/cm2 and exposure time was 15, 30, and 60 minutes. The concentration of 13C in Daphnia magna decreased with increasing exposure time. The Daphnia magna exposed to UV-B for 15 minutes intakes phytoplankton as much as control, while 30 minutes and 60 minutes exposures were lower than control. The lower concentrations of 13C observed in Daphnia magna were due to less intake of phytoplankton caused by the UV-B exposure.
Authors:S. Watanabe, Y. Iida, N. Suzui, T. Katabuchi, S. Ishii, N. Kawachi, H. Hanaoka, S. Matsuhashi, K. Endo, and N. Ishioka
Copper-64 was produced by the 64Ni(p, n)64Cu reaction using enriched 64NiO target. We investigated and compared the production yield of 64Cu for proton beams of various energies by using a thick target. Enriched 64Ni was recovered with high yield by simple procedures. Imaging studies using positron emission tomography (PET) and positron
emitting tracer imaging system (PETIS) were performed. We obtained clear images in PET and PETIS studies. The results of this
study indicate that 64Cu can be utilized as a biomedical tracer for the molecular imaging both in animals and plants.
Authors:T. Sakashita, T. Hama, S. Fuma, M. Doi, Y. Nakamura, N. Ishii, and H. Takeda
To investigate the possibility of 14CO2 fixation using microorganisms in a high-dose area, the photosynthetic activity (specific production rate: SPR) and cellular proliferation (colony forming unit: CFU) of Euglena gracilis Z irradiated with gamma-rays at a dose of 0 to 500 Gy were determined. The dose responses of SPR and CFU suggested that it was possible to operate a CO2 fixation system of Euglena up to 100 Gy. Even at a dose of 500 Gy, about half of the photosynthetic activity under non-irradiated condition was considered possible.
Authors:T. Chu, V. Navarrete, H. Kaji, G. Izawa, T. Shiokawa, K. Ishii, S. Morita, and H. Tawara
Proton induced X-ray analysis has been studied by the 5 MV Van de Graaff of Tohoku University emphasizing on backing materials
and angular dependence of background. The method has further been applied to analyses of some environmental samples. From
experimental results, it was found that 4 μm Mylar foil among Formvar, Mylar and carbon gives sufficiently low background
spectrum, high sensitivity and good mechanical strength. The detection limit is much improved at the backward direction with
respect to the incident beam comparing with that at 90° which has usually been adopted. The analytical results on soil and
aerosol samples were compared with those by the Atomic Absorption Spectrophotometrical method (AAS). Vanadium can easily be
analysed by this method, but not by the AAS method. Milk and human milk were also analysed.
Authors:H. Muramatsu, S. Yoshizawa, T. Abe, T. Ishii, M. Wada, Y. Horiuchi, and R. Kanekatsu
The concentration of 7Be in surface air at Nagano City has been measured during the period from August 2000 to March 2005. The average monthly concentrations
of 7Be in surface air were in the range of 3.3–14 mBq/m3 with pronounced two peaks in spring and autumn. It took 30–40 hours to recover the 7Be concentrations observed before, once 7Be was washed out by wet precipitations. For a pronounced increase in the concentrations of 7Be found in winter, a low-pressure trough coming close to the Japanese Islands with high concentrations of 7Be is responsible under the characteristic distribution of atmospheric pressure around the Japanese Islands.
Authors:Y. Wu, S.-Y. Kim, D. Tozawa, T. Ito, T. Tada, K. Hitomi, E. Kuraoka, H. Yamazaki, and K. Ishii
A macroporous silica-based supramolecular recognition absorbent (Calix + Dodecanol)/SiO2–P, was prepared by successive impregnation and fixing the 1,3-[(2,4-diethylheptylethoxy)oxy]-2,4-crown-6-Calixarene (Calixarene-R14)
and its molecule modifier 1-Dodecanol onto SiO2 silica-based polymer support. The characterization of (Calix + Dodecanol)/SiO2–P was examined by thermal gravimetry and differential thermal analysis and electron probe microanalysis. Relatively large
separation factors of Cs and other metal ions (αCs/Mn+) above 60 were obtained in the presence of 3 M HNO3. The adsorption data of Cs(I) fitted well with Langmuir isotherm and the maximum adsorption capacity was estimated to be
0.19 mmol g−1. The Cs(I) in 3 M HNO3 were also effectively adsorption on (Calix + Dodecanol)/SiO2–P in the column operation, and the loaded Cs(I) was successfully eluted with an eluent of H2O. The column packed with (Calix + Dodecanol)/SiO2–P had excellent reusability after three cycles.