Use of a dual-labelled oligonucleotide as a DNA dosemeter for radiological exposure detection.

A reporter molecule consisting of a synthetic oligonucleotide is being characterised for a novel damage detection scenario for its potential use as a field-deployable, personal deoxyribonucleic acid (DNA) dosemeter for radiation detection. This dosemeter is devoid of any biological properties other than being naked DNA and therefore has no DNA repair capabilities. It supports biodosimetry techniques, which require lengthy analysis of cells from irradiated individuals, and improves upon inorganic dosimetry, thereby providing for a more relevant means of measuring the accumulated dose from a potentially mixed-radiation field. Radiation-induced single strand breaks (SSBs) within the DNA result in a quantifiable fluorescent signal. Proof of concept has been achieved over 250 mGy-10 Gy dose range in radiation fields from 6°Co, with similar results seen using a linear accelerator X-ray source. Further refinements to both the molecule and the exposure/detection platform are expected to lead to enhanced levels of detection for mixed-field radiological events.

A discrete model for streaming potentials in a single osteon.

A mathematical model for streaming potentials in an osteon is proposed, taking into account the microstresses in the vicinity of the Haversian Canal. With the help of the finite element method, a boundary problem for the fluid pressure amplitude in the osteon is investigated when the bone sample is subjected to harmonic loading. A numerical analysis of the intra-osteonal potential is performed. It is found that there exists an azimuthal asymmetry which increases with the enlargement of the Haversian Canal. The results of the numerical modeling of the intra-osteonal potential are in accordance with the available experimental data.

An anatomical model for streaming potentials in osteons.

An anatomical model for streaming potentials in osteons is developed to characterize the electromechanical effect in bone. The model accounts for the microstructure of the osteon and is based upon first principles of electrochemistry, electrokinetics, continuum mechanics and fluid dynamics. Intra-osteonal potentials and their relaxation times are numerically evaluated. Many of the previously reported observations of potentials in osteons and across macroscopic specimens are explained for the first time in terms of an electrokinetic model. The cusp-like behavior of intra-osteonal potentials is explained, the dependence of the potentials on solution viscosity and conductivity is demonstrated, and insight is gained relative to the time dependence of stress generated potentials.