New imidazopyridopyrimidine:naphthyridine base-pairing motif, ImN^[N]:NaO^[O], consisting of a DAAD:ADDA hydrogen bonding pattern, markedly stabilize DNA duplexes

The new imidazopyridopyrimidine:naphthyridine base-pairing motifs, ImO^[O]:NaN^[N] and ImN^[N]:NaO^[O], were designed. Among the base pairs examined, DNA duplexes containing ImN^[N]:NaO^[O] pair(s) consisting of a DAAD:ADDA hydrogen bonding pattern (D = donor, A = acceptor) were markedly stabilized thermally and thermodynamically

Determination of radiation produced by neutrons in heavily exposed workers of the JCO criticality acccident in Tokai-mura for estimating an individual\u27s neutron fluence.

In the Tokai-mura criticality accident, three workers were heavily exposed. Biological materials, such as blood, urine, vomit and hair, were collected from the workers and analyzed for radioactivities, produced by the neutron irradiation. Activation products, such as 24Na, 42K and 82Br, were found in these materials by gamma-ray spectrometry. The radionuclide of the highest activity observed in biological materials was 24Na, e.g. the concentrations of this nuclide in the blood samples from the three patients at the accident time were 169, 92 and 23 Bq/ml, respectively. The concentrations of stable sodium in the same samples were determined by ICP-AES to obtain specific activities of 24Na (concentration ratio between the produced 24Na and stable 23Na), which are essential for estimating the neutron fluences and radiation doses. The specific activities of 24Na obtained for the three patients through the blood analysis were 8.2 x104, 4.3 x104 and 1.2 x104 Bq24Na/g23Na. Based on these values, individual\u27s neutron fluences were estimated to be 5.7 x1011, 3.0 x 1011 and 0.85 x 1011 cm-2, respectively

Estimation of radiation doses for three exposed patients in the Tokai-mura accident based on 24Na in their biological materials.

Concentrations of radionuclides in blood, urine, vomit and hair samples from three heavily exposed patients were determined by gamma-spectrometry. Activation products such as 24Na, 42K and 82Br were identified in these materials. The radionuclide of the highest activity observed in biological material was 24Na, e. g. the concentrations of this nuclide in the blood samples from the three patients at the accident time were 169, 92 and 23 Bq ml^-1^. Concentrations of the stable Na in the same samples were determined by ICP-AES to obtain specific activities (concentration ratio between the produced 24Na and stable 23Na). The specific activities of 24Na obtained for the three patients through the blood analysis were 8.24*10^4^, 4.34*10^4^ and 1.23*10^4^Bq24Na/g23Na, respectively. Based on these values, neutron fluences for the three patients were estimated to be 5.7*10^11^, 3.0*10^11^ and 0.85 *10^11^ cm^-2^, respectively. Absorbed doses for three patients due to neutrons were estimated to be 5.4, 2.9 and 0.81Gy, those due to gamma-rays 8.5-13, 4.5-6.9 and 1.3-2.0Gy, respectively