Diffusion coefficient of36Cl in silver chloride was revealed to be about 1×10-10-4×10-11cm2⋅s-1in the range of 400°C-200°C by means of radioactive tracer measurements. Activation energy for diffusion was calculated about 0.13 eV. These results were different from those obtained by Maurer and Compton.
A landfill leachate, which contains large amounts of mierobially refractory humie substances, was irradiated with60Co γ-rays under several conditions and the modification of its biodegradability was examined. The effects of initial pH and dose rate on the modification were found to be insignificant. The apparent effect was observed for the initial concentration of the humie substances. High biochemical oxygen demand (BOD) value was obtained as the initial concentration was higher. As the initial concentration was lower, in contrast, the decreasing rates of total organic carbon (TOG) and chemical oxygen demand (COD) were high. Therefore two possible designs of the combined radiation-microbial processes with and without dilution are proposed. Both processes require only about 30% of the irradiation dose, compared with a simple radiation process.
Organ volume was experimentally and clinically determined using single photon emission computed tomography (SPECT) . In organ phantom filling with99mTcO4-, the error was less than 3.3% in the volume over 400 ml but 11% at 200 ml. In 28 cases of patient, liver and spleen volume were measured by SPECT and X -CT. Good correlation was founded between SPECT volume and X-CT volume (r=0.99, n=49), although SPECT volume were 16% higher than X-CT volume (y=1.16 x+11.6, x: X-CT volume, y: SPECT volume) .
In order to know the potential merits of99mTc-pyrophosphate (99mTc-PYP) skeltal imaging, a comparative study was carried out by administering to the rabbit85Sr-chloride (85Sr), classical bone-seeking agent, and99mTc-PYP simultaneously. Radioisotopic distribution was investigated as regards their deposition in the pelvic bones, and sharpness of the skeletal scintigrams, too. Both agents were remarkably afnitive to the skeletal system and there were remarkably differences in their temporal deposition pattern. Marked deposition was observed of either agent in the metaphyses. With99mTc-PYP, the vertebral and costal systems were delineated symmetrically and each vertebral body was distinctly depicted as such99mTc-PYP many possess the following merits over85Sr; (1) owing to its physical properties, sullieiently large radioactivity of99mTc-can be administered; (2) body burden of radiation absorption is reduced; (3) skeletal scintigrams of high quality are obtainable in ashort period of time.
Based on the high radioactivity uptake of some14C-labeled D-amino acids in tumors and pancreas of mice, this investigation was undertaken to ascertain possible usefulness of radioactive D-methionine as a nuclear imaging agent. Radioactivity derived from D- [3, 4-14C] -methionine in Ehrlich solid tumor was approximately three times higher than that from the Lisomer, but was the same as for mouse pancreas. Excretion rate of the radioactivity of D- [14C] -methionine into urine was approximately two times faster than that of the L-isomer. As compared with two potential imaging agents, 1-aminocyclopentane-1-carboxylic acid and α-aminoisobutyric acid, D-methionine showed almost the same radioactivity biodistribution in tumor and pancreas. These results suggest potential for D-methionine as a mother compound for use in tumor and pancreas imaging.
Extremely large separation factors (>102) were found for Na-Mg, K-Ca and Rb-Sr metal ion pairs on a cyptomelane-type hydrous manganese dioxide (CRYMO) ion exchanger. Ca2+and Sr2+ions were quantitatively separated from a thousand times of K+and Rb+ions on mole basis, respectively, by using the CRYMO column. The hopeful utilities of the CRYMO are suggested for the radiochemical ion-exchange separation of radiomagnesium and radiostrontium from K and Rb salt targets.