Volatilization behavior of210Po contained in airborne dusts in the temperature range of 200-800°C was investigated in an atmosphere of nitrogen. It is revealed that the volatilization feature of210Po in airborne dusts in an atmosphere of nitrogen as a function of temperature can be expressed in a stair-like shape with two steps. The tendency is similar to the previous results obtained in air. The previous and present data may suggest that210Po in airborne dusts consists of two or more different kinds of chemical species.
A direct reading high dose rate-meter which was composed of a measuring cell enclosing dodecane and a tera ohm-meter was devised. Dependence of electric resistance upon dose rate and effect of temperature of this measuring cell during γ-irradiation were compared with those of the detector enclosing liquid parafne reported previously. It was thereby found that this cell was superior in the linearity of electric resistance for the dose rate and reproducible to about ±2% on repeated irradiation. In addition, this measuring cell was easier to make and could be regenerated by washing the cell of decreased resistance. This dose rate-meter was suitable for the measurements within a range of dose rate of 103to106 R/h.
A study of the gas chromatographic/mass spectrometric/computer assay (GC-MS-CPU) for isotope ratio of nitrogen-15 amino acids as their N-TFA butyl esters has been carried out. A Shimadzu-LKB 9000 gas chromatograph mass spectrometer computer combined system was used. 15N isotope ratio of separated amino acid peaks by gas chromatography was measured their mass spectral fragmentation. These was a good agreement among the samples. And mass chromatography assay was useful in the analytical separation and determination for gas chromatogram peaks of amino acids.
A freeze-dried-microautoradiographic technique by whole body sectioning was improved in order to observe the distribution of radioactivity in the main organs or tissues of a rat. The whole body of a fetal rat was cut at 7μ with a sledge microtome (Leitz, 1400) in a cryostat kept at -20°C. The section was placed on a cooled glass slide and transferred to a specimen chamber which was vacuous at about 10-2mmHg. To prevent the water in the section from evaporating unequivalently as ice vapor, about 20 ml of water was frozen in the specimen chamber. After the freezedrying was completed, the specimen chamber was allowed to be warmed to room temperature. An improved dry-mounting autoradiogram was prepared. The stripping type of nuclear emulsion was put on a thin plastic film, such as Saranwrap, suported with the glass plate in a dark room. A section slide was put on the dried emulsion plate very gently. In order to reduce shifting of the section and to avoid loose contact of the emulsion with the specimen section, the film face has been exposed to steam (about 50°C) for a second. Then the section slide was stood in a dark box at -4°C for exposure. After four weeks of exposure, the specimen was photographically processed. A double staining method with haematoxylin-eosin was used. Distribution of3H-thymidine in a fetal rat was investigated with the above-mentioned modified autoradiographic techniques. Cell proliferation in the intestinal epithelium was almost confined to the Lieberkühn crypt. Numerous mitctic figures were seen in the periosteum. These information on cell dynamics not only indicate proliferation of these cells but also elucidate the relationship between the functional development and morpho genesis of these tissues in fetal life.
In routine clinical studies, we have experienced some cases of transferring anatomical marks to scintigrams through the scintillation camera. It was thought that radioactive point sources could be used as anatomical marks.However, this method resulted in an ill-defined area of brightness. A marking equipment for scintillation camera used in this study consists of linear potentiometer and sine-cosine potentiometer. Moreover we designed a marking method for a data processing system using the marking equipment for scintillation camera. A data processing system of scintillation camera is composed of EDR-4000 (8K core memories), MT recorder, CRT display, graphic display unit, and is connected by on-line with scintillation camera. A marking program was made in order to record marking addresses on a processed image. Using this soft program and graphpen of graphic display unit, we transferred marks to processed image by points and lines. The subtraction scintigraphy using198Au-colloid and75Se-selenomethionine was performed on cases of pancreas carcinoma. After marking addresses were recorded on a processed image by this marking method, the signals from the scintillation camera were fed into input controller. Then these signals with marking points were transferred from computer to MT recorder. The subtraction scintigraphy by this system made it possible to examine each picture with198Au-colloid or75Se-selenomethionine at different times.