Abstract: Mice of different ages ranging from 1.5 to 12 months have been exposed to gamma rays in an effort to determine the change in radiosensitivity with age. The dose necessary to cause 50% killing was determined for each age group and sex. No change in sensitivity with age was observed with either sex, although the experimental error in the case of the males was quite large. The females were found to be more resistant than the males.

Introduction. The main objective of the Metallurgical Project was the preparation of large quantities of plutonium 239, an isotope of element 94, by the interaction of neutrons and uranium. At the beginning, only predictions of its chemical and biological properties could be made since it is a new element. It was predicted that it would be toxic to tissue by virtue of its high atomic weight, and in addition, that it would be toxic by virtue of its radioactivity. Thus, the preparation and use of the element on a large scale meant the manipulation of, and possible exposure to, toxic quantities. It was, therefore, of practical importance to obtain data which would elaborate on the predicted toxicity. The objectives of the work reported here were to establish the acute toxicity of plutonium in experimental animals and to study the distribution of the element in the body after the administration of a wide range of doses. In the interest of economy of what was, at that time, a rare substance, and of animals and facilities, these two objectives were frequently pursued in the same experiment. The information obtained from the separate experiments is therefore frequently incomplete in one or another respect. …

From introductory paragraph: "In a slightly hypocritical water boiler the introduction of a single neutron may give rise to a fairly large burst of neutrons which dies out slowly. As was shown some time ago by Frankel and Nelson with the help of A. Horn the statistics of this multiplication process can be treated in a simple way for the hypothetical case that the number of neutrons produced per fission is two."

From abstract: "The report describes the complete structure of barium hydrogen phosphate, Ba HPO4, as determined by means of x-ray diffraction. The crystal is orthorhombic, with cell dimensions given by a=5.71 A b=7.05 A c=4.61 A. The calculated density is 4.15gm/cm[^]3 for two molecules in the unit cell. The space group is C[subscript]2v[superscript]7-pmn. The barium, phosphorus, and two sets of oxygen lie in the plane of symmetry. The third set of oxygens are in general positions. Parameters for these atoms have been found, and interatomic distances calculated. The positions of the hydrogens are indicated by the characteristics O-H-O distance (2.58A) between two oxygens."