Authors:J. Koarashi, K. Akiyama, T. Asano, and T. Yokota
The effects of incorporating tritiated water into a 14C-sampling system in sample preparation and 14C activity measurement by liquid scintillation counting were investigated. Experiments derived the limit of water content in the prepared sample, and also demonstrated that 14C activity can be determined without any interference from 3H contamination for a clear-sample solution. The results enabled us to estimate the permissible relative humidity of air required for accomplishing sample preparation and 14C activity measurement. These showed that for sampling of air with less than the permissible relative humidity, total 14C activity in airborne effluent can be evaluated accurately without dehumidification of air.
Authors:A. Murotomi, M. Yokota, Y. Miyano, T. Sakane, and K. Fukuchi
The infinite dilution activity coefficients of alkane (hexane, octane, decane and dodecane) in alkane (hexadecane and octadecane)
were measured in the region of 313–470 K using a gas stripping method. The experimental results were predicted by the modified
ASOG previously proposed.
Authors:T. Hashizume, A. Yokota, A. Saiki, and K. Terayama
Potassium tantalate was formed to pyrochlore structures on the tantalum substrate by hydrothermal or electrochemical method.
In synthesizing process of potassium tantalate, a crystal structure of the substrate surface seemed to be an important factor.
Potassium tantalate was synthesized with a simple equipment only, low temperature of 323 K or over, low concentration of 2–4
mol per liter potassium hydroxide aqueous solution and short time.
Authors:S. Kojima, T. Saito, J. Takada, M. Furukawa, H. Oda, T. Nakamura, and K. Yokota
Concentrations of eighteen trace elements at the sediment-water interface in Biwa Lake were determined by neutron activation analysis. Release of iron, manganese and arsenic from the sediment to the pore water was observed under anoxic conditions. The concentrations of Sb in the pore water as well as Na were nearly constant between the surface and the depth of 40 cm. The behavior of Sb differed from that of As at the sediment-water interface, since the partition coefficient of Sb differed from that of As.
Authors:T. Nakanishi, Y. Okuni, J. Furukawa, K. Tanoi, H. Yokota, N. Ikeue, M. Matsubayashi, H. Uchida, and A. Tsiji
We present water imaging of a plant sample both by neutron beam and positron emission tracer imaging system (PETIS). The former method provided static water profile in a plant sample as well as that in the vicinity of a root imbedded in soil. Not only X-ray film but also CT method using a cooled CCD camera is presented. Through non-destructive water image in an X-ray film, root development as well as 2-dimensional water movement toward the root was analyzed. Spatial water image was constructed from 180 CT projection images, taken at an interval of one degree while rotating the sample, through a CCD camera. In the case of a soybean root, there was a water gradient toward a root in soil and gave minimum value at about 1 mm far from the surface of a root. The water absorbing part in a root was gradually shifted downward with the root development. We also present real time water movement by PETIS, where water was labeled with a positron emitting nuclide, 15O. The transportation of 15O-water within a plant was relatively slow and water uptake was observed only at the lowest internode, between a root and the first leaf, during 20-minute measurement.