Distinct Effects of Chemical Toxicity and Radioactivity on Metabolic Heat of Cultured Cells Revealed by "Isotope-Editing".

Studying the toxicity of chemical compounds using isothermal microcalorimetry (IMC), which monitors the metabolic heat from living microorganisms, is a rapidly expanding field. The unprecedented sensitivity of IMC is particularly attractive for studies at low levels of stressors, where lethality-based data are inadequate. We have revealed via IMC the effect of low dose rates from radioactive β-decay on bacterial metabolism.

Measurement of the scattered neutrons using the shadow cone methodology in a neutron calibration bunker.

In this work, the contribution of scattered neutrons, in a neutron calibration bunker, was determined using the shadow cone technique. The measurements of the ambient dose equivalent rate in the presence and absence of the shadow cone were used to calculate the contribution ratio of scattered neutron, and to perform the needed correction for the scattered neutrons. The scattered neutron correction was performed according the recommendation of the ISO/DIS8529-2, and the results agreed to the inverse-square law.