Harlan's method for liquid scintillation counting of14CO2was modified to achieve rapid sample preparation and optimum counting results for 14CO2in aqueous Na214CO3-NaOH sample solutions, in which total concentration of Na2CO3and NaOH ranged from 0.2N to 1.0N and carbonate fraction in normality varied from 10% to 50%. The original procedure for sample preparation was not simple enough to prepare many samples. It also had a possibility to increase error owing to use of eye-measured gel powder, Cab-O-Sil. An attempt was made to find an improved procedure. Suitability of the original scintillator solution for counting of the above sample solutions was open to question, because relation between samples and counting results had not been fully described in Harlan's report. Various scintillator solutions were examined to select the optimum one. Scintillation mixtures subjected to examination were counted in Packard Tri-Garb liquid scintillation spectrometer Model 3002, the sample chamber being kept at 5°C. As a result, the following modified procedure was found to be advantageous for rapid sample preparation and accurate counting of our samples. Four handred milliliters of absolute ethanol and 25g of the gel powder are mixed and the resultant slurry is partially diluted with toluene. The mixture, 4g of PPO, and 15mg of POPOP are placed in a 1-liter volumetric flask and again diluted to the mark with toluene. A counting sample is made up by mixing 15ml of the scintillator solution and 0.5ml of a Na214CO3-NaOH sample solution in the standard glass counting vial. A piece of aluminum foil is attached on top of the vial prior to capping, if protection of the vial cap against contamination is desired. The scintillation mixtures are counted in the counter at a gain setting of 21 with window openings 50-1000 to obtain maximum counting efficiency. The aluminum foil attached on top of a vial increased counting efficiency by 2%. This effect being included, the mean counting efficiency over scintillation mixtures, which were made up in four combinations of total alkalinity and carbonate fraction levels, was 73.5%. Counting efficiency increased within the range of ±0.6% from the mean as total alkalinity and carbonate fraction increased. Background was about 65cpm.
With basic lavas in radioactive disequilibrium, the content of uranium and thorium was determined by the neutron activation method, and also the content of lead-214 and lead-212 by gamma-ray spectrometry. These lavas revealed radioactive disequilibrium by means of alpha-and gamma-ray interpretation. It seems that Th/U ratio of basaltic lava of historical age is higher than that o f andesitic one, and that the radium content of tholeiite lava is nearly normal as compared with its uranium content, while that of alkali and high-alumina lava highly excessive.
In order to reserve fixedly the hydrophylic and lipophylic metabolites labelled with soft β emitters in a light microscopic specimen, a new microautoradiography technique was devised. The technique, so called “Dry Method”, is related to nuclear emulsion coating method as follows; (1) stripping the nuclear emulsion from the glass plate in glycerin water, (2) inverting and then mounting the emulsion on saranwrap-covered glass plate in the same water, (3) desiccating the emulsion at room temperature, (4) mounting the emulsion-saranwrap plate on the labelled specimen and then removing only glass plate, (5) expanding the emulsion on the specimen glass slide by slight exposure to the hot-vapour for a moment, in order to give a good contact, (6) keeping in a dark box at 4°C for an adequate period, (7) stripping only saranwrap piece from the emulsion in distilled water, (8) developing and fixing the emulsion, and (9) staining the specimen. Counting efficiency (silver grains/μ2//μCi) was enhanced by this technique compared to the ordinary wet technique. The dry technique was not increasing physical and chemical fogging. Silver grains in Fuji ET-2F and in Fuji ET-2E, respectively, were plotted against tritium contents in arbitrary units after different short exposure times, using both dry and wet method. From the results obtained by dry method as well as wet method, the silver grains in ET-2F increased quite substantially with increasing contents, whereas the grains in ET-2E and3H contents were not parallel.
Skeletal muscle scanning with I-125 MAA and131CsCl was developed for obtaining definitive data on the distribution of muscles involved in patients with progressive muscular dystrophy. With these labeled compounds delineation of the distribution of radioactivity corresponded exactly with the contour of each independent muscle mass, and the muscles involved were seen as cold area of decreased radioactivity. By serial scanning, evaluation of the progress of the disease is possible, and the scans might be useful in making decision regarding surgical procedure and rehabilitation program.