Observation of γ-ray background has been done by using a Ge (Li) semiconductor detector when it was placed inside the lead shielding material. With the aid of a very simple model calculation, the concentration of210Pb radioisotope embedded in the lead material has been estimated to be 0.1-0.4 (Bq/Pb-g) (3-12 (pCi/Pb-g) ) . The origin of Pb-KX-ray emission, the highest peak in the background spectrum, has been investigated by comparing the210Pb-47 keV 7-ray and Pb-KX-ray peak counts. As the result, about 50±30% of Pb-KX-ray production is estimated to be due to the Pb-K shell photoionization which is induced by the bremsstrahlung of210Bi β-ray.
A radiochemical group separation using APDC extraction was applied to the neutron activation analysis of normal and cadmium injected rat liver. In order to optimize determinations of induced radionuclides with various half lives, the gamma-ray spectra were obtained after various decay times. Eight elements, Cd, Co, Cu, Fe, Mn, Mo, Se and Zn, were determined from rat liver samples within 12 day after irradiation. Although Cd, Cu and Mo in normal rat liver could not be detected by nondestructive method, they could be determined after the extraction. The tendency was seen that the concentration of all the elements as mentioned above are increased by cadmium injection. In particular, zinc and copper exhibited high values.
The adsorption behavior of radionuclides (137Cs and85Sr) on sand and the influence of pH on the distribution coefficient have been studied. The adsorption obeys the Henry adsorption isotherm, which is an approximation of Freundlich adsorption isotherm, in the concentration range of 10-9-10-12mol/l for both137Cs and85Sr. Their distribution coefficients do not depend on the concentration of radionuclides provided that sand particle size, pH, concentration of coexisting cations and so on are fixed.
Absorption, distribution, excretion, and metabolism of 5, 8-dihydro-5-methoxy-8-oxo-2H-1, 3-dioxolo [4, 5-g] quinoline-7-carboxylic acid (miloxacin), a new antimicrobial agent, were studied in female rats by using14C-miloxacin which was administered orally to the animals in a dose of 50 mg/kg. 14C-Miloxacin was absorbed rather fast and the radioactivity of14C distributed widely in a variety of tissues. Peak concentrations of14C in serum and tissues occurred 1 to 2 hr after dosing, and were approximately 60 μg equivalent of miloxacin per ml or g in serum, liver and kidney. Excretion of14C in urine and feces was fast, and recoveries of14C during 48 hr period were approximately 30% in urine and 60% in feces. Concentrations of intact14C-miloxacin were higher in serum and kidney while lower in liver. Major metabolites in excreta were the demethoxy derivative (M-1) and the glucuronide of miloxacin; and as minor metabolites five other metabolites were identified. As sex differences, the following facts were observed; concentrations of14C in serum and tissues were generally 1.2 to 1.6 times higher in female rats than those in male rats, and the capacity to metabolize miloxacin, especially in the glucuronic acid conjugation, was rather lower in female rats than that in male rats.