[en] Cells were irradiated with 60, 150, or 250 rad of paired and single deuterons in three separate experiments and mitoses were continuously accumulated with colcemid or sequentially accumulated at hourly intervals. Graphs are presented to show percentages of cells in mitosis after irradiation. There was a decline in frequency of mitoses after irradiation and induced delay was considerably greater for the 250 rad dose. All three doses showed a clear cell stage sensitivity effect with the period closest to mitosis at the time of irradiation being most susceptible to radiation. Irradiation with paired deuterons resulted in more aberrations than single deuterons

[en] Radiobiological measurements were made on the 80 MeV d⁺ → Be beam. Biological test systems included growth inhibition of Vicia seedlings under aerated and hypoxic conditions and determination of survival curves of Chinese hamster cells under aerated and hypoxic conditions. Results showed no indication of decreasing OER with increasing neutron energy

[en] Following irradiation with monoenergetic neutrons of 15.1, 1.91, 0.43, and 0.23 MeV, cells of broad bean roots are delayed in progression through the cell cycle. There is an exponential relation between cells progressing (''surviving'') into mitosis and dose over a range of time periods. Relative biological effectiveness (RBE) increases with decreasing neutron energy and the two lowest energies are similar in effect. The RBE-neutron energy dependence for this largely transitory delay phenomenon in general approximates that found for permanent radiobiological endpoints, possibly indicating that this effect depends on the square of the energy absorbed in sites of nuclear size or smaller

[en] A study has been made of the biological effects of the neutron beam produced by 80 MeV deuterons on Be at the University of Maryland. Measurements of OER were obtained from dose-response curves for inhibition of root growth of Vicia seedlings (1.68), and from the survival curves of a line of V79 Chinese hamster cells (approximately 1.7). Comparison with other OER values gives no indication of decreasing OER with increasing neutron energy. (U.K.)