(1978). Effect of Metronidazole on the Split-dose Recovery of Yeast. International Journal of Radiation Biology and Related Studies in Physics, Chemistry and Medicine: Vol. 34, No. 5, pp. 471-474.
Abstract Gamma irradiation of coumarin in aqueous solution gives fluorescent products proportional to radiation dose. Our earlier results showed that hydroxyl radical is mainly responsible for this effect. Fast neutron irradiation gave similar results but with a dose response of 0.4 relative to that of gamma dose response. This report gives the effect of adding boric acid to coumarin and irradiating with thermal neutrons in a nuclear reactor. The relative response to the high LET alphas and 7Li recoils from 10B(n, α)7Li reaction, is found to be approximately 8% as compared to gamma rays. This value is compatible with the G OH value for these heavy charged particles as compared to G OH of gamma rays in neutral aqueous solution.
Monte Carlo estimates of neutron backscatter from an infinite slab of standard man composition have been arrived at, in the incident neutron energy range of 0.025 eV-10 MeV, for normal and isotropic incidence. The information obtained includes (i) the total and thermal components; (ii) the spectrum; and (iii) the angular distribution of the backscatter component. As the thermal neutron component of the backscatter would be recorded by thermal neutron personnel monitoring devices, the thermal backscatter response of such devices for various incident energies has been estimated, and appropriate correction factors recommended. This correction is negligible at higher incident neutron energies (it is of the order of 0.5% in the range 1–10 MeV) whereas it increases to 50–60% in cases where thermal and intermediate energy neutrons are incident. Further, the secondary gamma dose resulting from (n, gamma) capture in tissue was considered. This dose was estimated at the surface of an infinite slab of standard man composition, and was found to agree with reported experimental values. This gamma dose would be recorded in the gamma radiation personnel monitoring device, as a superfluous dose. The relevant correction factor has therefore been estimated. This correction is negligible in the neutron energy range 1–10 MeV and reaches a steady value of about 10% in the neutron energy range of 10 keV to thermal. A composite personnel monitoring device for both thermal and intermediate energy neutrons, is suggested.
(1976). Effect of Chemical Protectors on Fast-neutron-induced Reversions in Yeast. International Journal of Radiation Biology and Related Studies in Physics, Chemistry and Medicine: Vol. 30, No. 6, pp. 585-588.
Abstract Abstract: Gamma dose response curve for phosphate (pi) release from dilute aqueous solutions of thymidine monophosphate (TMP) has been extended for very low and high doses, viz. 3 K rad to 200 K rad. Results show that Pi release in nitrogen saturated solution increases as dose increases. Possible reasons are discussed. The oxygen enhancement ratio for low doses is higher thaft what is reported earlier; whereas for high doses It is less than 1.
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