Radiolysis of hydrogen cyanide is studied to elucidate the chemical action of ionizing radiation on simple compound which is of interest in primordial organic chemistry.
G (-HCN) is seen to increase with increasing hydrogen cyanide concentration tending to 8 ?? 9 at 0.1 M in either air-free or aerated system, however the presence of oxygen reduces G (-HCN) very effectively at lower concentration.
The limiting value in G (-HCN) when all the free radicals produced by water radiolysis are assumed to react with hydrogen cyanide is obtained as 5.9. This is in close agreement with well established values in radical yield in water and indicates the participation of these radicals in radiolysis of hydrogen cyanide at low concentration.
High G (-HCN) at higher concentration is too large to be accounted for in this way and some other effect principally like polymerization of hydrogen cyanide must contribute to the increase in radiolytic yield.
At high concentration of hydrogen cyanide, an absorption band at 295 mu appears, which is assigned to HCN tetramer by comparing with the absorption curve of tetramer extracted from azulmic acid prepared from hydrogen cyanide and triethylamine.
As the radiolysis products, ammonia, carbon dioxide and hydrogen are observed.

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Comparative studies of Cs and Rb metabolism were made with an adult male of human subject using ¹³²Cs and ⁸⁶Rb double-tracer method. Whole body retention and distribution after single oral administration were investigated by a whole body counter-scanner at the National Institute of Radiological Sciences, and total excreta in urine and feces that were collected for 9 days after the administration were measured separately by the same detector.
Marked differences were found in the biological half-lives, excretion patterns and distributions in the whole body between the two radionuclides.
Whole body retention could be expressed by two-component exponential function of time for the both nuclides, but short-term component had a shorter half-life (1.0 day) for ¹³²Cs than that for ⁸⁶Rb (6.0 days) and long-term component had a longer-life (72 days) for ¹³²Cs than that for ⁸⁶Rb (53 days).
Total excretion of ¹³²Cs for the first 5 days after the administration was correspondingly larger than that of ⁸⁶Rb, but fecal excretion of ⁸⁶Rb was slightly larger than that of ¹³²Cs which resulted in a large disagreement in values of urinary-to-fecal excretion ratio between the two.
Whole body distributions obtained with the elapse of time since the administration indicated that ⁸⁶Rb was transferred to its final compartments within 3 days, but ¹³²Cs needed more than 10 days. At the equilibrium in distribution ¹³²Cs concentrated in muscular tissues more specifically than did ⁸⁶Rb, but ⁸⁶Rb was present more in liver, heart, and brain etc., than ¹³²Cs.
These results suggest that Cs must have a different metabolic pathway to that of Rb, and that effective elimination of ¹³⁷Cs from the human body can be made by some means when applied before 3 days after accidental ¹³⁷Cs intake.

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The yearly changes of the exposure doses received by workers in radiological occupations at Kyushu University Hospital from September 1962 to March 1966 were reported.
The exposure doses have been gradually decreasing every year. By quality of radiation, it was noted that there has been a marked decrease in the γ-ray exposures, and by occupation there has been a notable decrease in the doses received by nurses. However, the X-ray exposure doses received by non-radiologists show a slight increase.
Further efforts should be devoted to reduce the exposure doses received by workers. Education on radiation disturbances and information on scattered rays as well as training on radioisotope handling should be continued.

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The measurement of the gamma ray spectra from the radioactive fallout produced by the fifth and sixth Chinese nuclear test explosions were made with a Ge (Li) detector. Many nuclides were identified in the gamma ray spectra without any chemical processing. The fission products as ^85mKr, ⁹¹Sr-^91mY, ⁹⁵Zr-⁹⁵Nb, ⁹⁷Zr-⁹⁷Nb, ⁹⁹Mo-^99mTc, ¹⁰³Ru ¹³¹I, ¹³²Te-¹³²I, ¹³³I-¹³³Xe, ¹³⁹Ba, ¹⁴⁰Ba-¹⁴⁰La, ¹⁴¹Ce, ¹⁴³Ce, and ¹⁴⁷Nd were identified. In addition to them, ²³⁷U and ²³⁹Np produced from ²³⁸U were also identified.

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Comparative study on the whole-body retention and distribution of ¹³⁴Cs was carried out for the rats of three different ages : new born, young, and adult rats. All measurements were made by gamma counting with a liquid scintillation counter for small animals. The ¹³⁴Cs retention in young and adult rats might be approximated to a exponential function associated with a few components, but in new born rats, being rather complicated, ¹³⁴Cs body burden decreased slowly in initial phase followed by faster decrease. The ¹³⁴Cs distribution in young rats did not differ significantly from that in adult rats. A more detailed study on ¹³⁴Cs metabolism in new born rats is in progress.

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Conditioned aversion to saccharin solution was demonstrated by whole-body irradiation at doses of more than 25 R in 100-day-old Wistar rats. The degree of aversion depended on radiation dose and the duration of this effect depended on the age of the irradiated rats. The repeated conditioning produced the same degree of aversion as in the first conditioning. The sugar solution had no effect as a conditioning stimulus.

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No significant effect of anaesthesia during irradiation on saccharin avoidance behavior was found in the 100 R X-irradiated rats in both cases of initial presentation of saccharin as a conditioning stimulus given either before or after the irradiation. The results obtained seem to indicate that saccharin avoidance behavior did not result from the discrimination of irradiated rats while receiving radiation.

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Differences in 30-day percent survival in dd/YF male mice after a single dose of 600 R were observed after three kinds of hematopoietic stimulation, i. e., fasting and refeeding, heavy breeding and low barometric treatment. Erythropoietic activity was estimated by measuring ⁵⁹Fe uptake for six hours into the femur and spleen after the stimulation. Number of colony forming cells in the bone marrow was determined by adopting the transplantation method. Mice appeared to be resistant when the hematopoietic activity is high and hematopoietic stem cells in the marrow are reduced.

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