It was previously reported by K. Takei that the color of HgI2·2HgS (yellow) turned black in sunlight and was restored when the darkened salts were kept in the dark or heated. The mechanisms of this reversible change in color were discussed by him and the discoloration was attributed to the evaporation of colloidal mercury printed-out by sunlight on the crystal surface and to the formation of HgI2and HgS on the crystal surface by the reaction between mercury and iodine or sulfur. The evaporation of mercury, however, was not experimentally ascertained by him. In the present work, we have studied the behaviour of mercury or iodine in this reversible color change utilizingHg*I2·2Hg*S orHgI*2·2HgSlabeled with203Hg or131I. Experimental results indicate the following mechanism. In sunlight, mercury is printed-out and I2 gas is formed and given of into the atmosphere. When the darkened salts are heated, the colloidal mercury vaporizes rapidly and yellow is restored. Also when they are kept in the dark at room temperature, it remains on the crystal surface, and yellow is restored.
In the supervoltage radiation therapy, it is theoretically natural that some activity is produced in the body of patient and the treatment bed. This activity is caused by (γ, n) nuclear reaction. Details of the radio-contamination induced by 26 Me V betatron were examined from the standpoint of radiation protection. 1) Main nuclides produced in the body by supervoltage X-ray irradiation are158O and118C. 2) If 20 cm thick portion of a human body is irradiated by 26 Me V X-rays, dose rate 40“R”/min and field size 10×10 cm, for 7.5 minutes, 150 μCi of15O and 5 μCi of11C are produced in the body. The activity is clearly detected by scintillation camera. 3) Also in the treatment bed, either of wood or of acrylite, 15O and11C are produced by the irradiation. 4) At present, X-ray dose rate of betatron is not very high and the amount of15O and11C produced causes no problem of radiation protection. 5) In future, however, some counterplan against room contamination should be considered when supervoltage X-rays of higher dose rate is used. Also some measure should be taken for the safe handling of irradiation field cone. 6) The amount of X-ray contamination in the electron beam is measured by utilizing (γ, n) nuclear reaction.
6-Iodopurine-131 I was synthesized by the exchange reaction of 6-IP with Na131 I. Specific activity of synthesized 6-iodopurine was 0.42 mCi/mg (0.52 mCi/ml), and the yield of 6-iodo purine-131 I was 52%. The autoradiol ysis was not detected in 25 days. Studies of distribution of 6-iodopurine131 I in mice and scintiphotography indicated that the intraperitoneally injected 6-iodopurine-131 I-was incorporated into the stomach and tumor. Considerably large amount of 6-iodopurine-131 I was found in the implanted tumor tissue 2 hours after intraperitoneal injection. Incorporation of 6-iodopurine-131 I in tumor nucleus was showed by the microautoradiography.
The difference in concentration of90Sr (S.U.) in bones was investigated by means of radiochemical analysis. The specimens were obtained from skull, sternum, rib, lumber vertebrae and pelvis of thirteen Japanese male adults. The mean value of the concentration of90Sr in each bone was: 0.33±0.08 S.U. in skull, 1.75±0.66 S.U. in sternum, 0.96±0.23 S.U. in rib, 1.42±0.30 S.U. in lumbar vertebrae and 1.40±0.29 S.U. in pelvis. Through statistical studies it was found that the difference between the90Sr concentrations in bones in two skeletal localities was significant with regard to all possible combinations but vertebrae pelvis party.