The spontaneous deposition behavior of polonium on several kinds of metallic wires was studied by using a liquid scintillation counting technique. After isolating210Po from Ra-DEF mixture, an aliquot of the 0.1 N HNO3-Po solution was subjected to the deposition procedure by dipping a fixed end part (10 mm) of a metallic wire for about 15 h at room temperature. By using liquid scintillation technique, the Po deposited on the wire were examined from aspects of the shape and peak shift of alpha-spectrum as well as the integral counts. It was found that the Al wire source gave an excellently resolved single peak at the highest pulse height, while the Pd, Pt, and Ni wire sources showed a tendency to shift toward lower pulse height side. The former was considered to reflect a sort of physico-chemical adsorption on the thin oxide layer of Al-wire surface, while the latter group is presumably due to diffusion effects as metallic Po deposits on metal surface. In the case of Al wire, the oxide layer formed by anodic oxidation also brought a superior alpha-spectrum. The Po adsorbed on active sites of Al oxide layer was satisfactorily sealed to prevent from dissolution into the scintillator by heating treatment at 120°C for 30 min. Thus, the210Po wire source suitable for varieties of nuclear researches could be easily prepared. Finally, the210Po Al-wire source (0.5 mm in diameter) was fairly well applied to the quenching correction in the determination of low-level tritium in recent precipitations.
Determinations of Mg-, Ca-, Cr-, Mn-, Fe- and Ni-content in akamatsu (P. densiflora), konara (Q. serrata) and ryoubu (C. barbinervis) which were grown on the serpentine soil, as well as in soil, were performed by the neutron activation method or the atomic absorption spectrophotometry. It turned out that contents of these elements was higher in leaves than wood. It was also found that Ni content in the leaves of konara as well as of ryoubu reflected the concentration of the acid extractable Ni in the serpentine soil. The elemental contents in akamatsu leaves were heavily affected by the characteristic contents of the serpentine soil. It is suggested that these trees are available for the indicator of soil-environment.
Biosyntehsis of13C-labeled starch was examined by using a small-scale apparatus. Tobacco leaves were placed in the cylindric photosynthesis chamber (14φ×50 cm) . After preincubation for 30 h in the dark, incubation with13C-labeled CO2was carried out for 48 h under irradiation with fluorescent lights. Labeled starch was extracted from the leaves and was purified. About 500 mg of13C-labeled starch can be obtained from 50 g of the leaves. The13C-abundance of the starch formed by the incubation was determined to be 82.0-92.0 atom % by mass spectrometry.
The variations of environmental gamma radiation flux were observed by using a new portable spectrometry recording system for 1 year. Spectrum analyses by the response matrix method have provided much information, and the artificial contribution can be separated from natural back ground dose by using the Thmethod or the three component method.
Chemical constituents of the commercially available “biodegradable” liquid scintillator solvents were elucidated by means of GC/MS analysis etc, as either the mixture of monosubstituted benzenes with the alkyl chain of carbon 10 to 13, or 1- (3, 4-dimethylphenyl) -1-phenylethane.