Damages of DNA in tritiated water.

Tritium is a radioisotope of hydrogen emitting low energy ß-rays in disintegration to 3He. DNA molecules are damaged mainly by ß-ray irradiation, and additional damages can be induced by break of chemical bond by nuclear transmutation to inert 3He. Deep knowledges of the mechanisms underlying DNA damages lead to better understanding of biological effects of tritium. This chapter reviews recent experimental and computer simulation activities on quantitative evaluation of damage rates by ß-ray irradiation and nuclear transmutation. The rate of DNA double-strand breaks in tritiated water has been examined using a single molecule observation method. The effects of ß-ray irradiation were not noticeable at the level of tritium concentration of ∼kBq/cm3, while the irradiation effects were clear at tritium concentrations of ∼MBq/cm3. The factors affecting on the DSB rate are discussed. A new image processing method for the automatic measurement of DNA length using OpenCV and deep learning is also introduced. The effects of tritium transmutation on hydrogen bonds acting between the two main strands of DNA have been examined using molecular dynamics simulations. The study showed that the collapsing of DNA structure by the transmutation can be quantitatively evaluated using the root mean square deviation of atomic positions.

High-precision robust monitoring of charge/discharge current over a wide dynamic range for electric vehicle batteries using diamond quantum sensors.

Accurate prediction of the remaining driving range of electric vehicles is difficult because the state-of-the-art sensors for measuring battery current are not accurate enough to estimate the state of charge. This is because the battery current of EVs can reach a maximum of several hundred amperes while the average current is only approximately 10 A, and ordinary sensors do not have an accuracy of several tens of milliamperes while maintaining a dynamic range of several hundred amperes. Therefore, the state of charge has to be estimated with an ambiguity of approximately 10%, which makes the battery usage inefficient. This study resolves this limitation by developing a diamond quantum sensor with an inherently wide dynamic range and high sensitivity for measuring the battery current. The design uses the differential detection of two sensors to eliminate in-vehicle common-mode environmental noise, and a mixed analog-digital control to trace the magnetic resonance microwave frequencies of the quantum sensor without deviation over a wide dynamic range. The prototype battery monitor was fabricated and tested. The battery module current was measured up to 130 A covering WLTC driving pattern, and the accuracy of the current sensor to estimate battery state of charge was analyzed to be 10 mA, which will lead to 0.2% CO2 reduction emitted in the 2030 WW transportation field. Moreover, an operating temperature range of - 40 to + 85 °C and a maximum current dynamic range of ± 1000 A were confirmed.

Refractive index measurements of solid deuterium-tritium.

Physical properties of tritium (T) and deuterium (D) have been of great interest as a fuel for nuclear fusion. However, several kinds of the physical properties in a cryogenic environment have not been reported. Optical properties in liquid and solid phases are indispensable for the quality control of the DT fuel. We study the dependence of the refractive index of solid DT on temperature. A dedicated cryogenic system has been developed and forms a transparent solid DT in a prism cell. Refractive index measurements based on Snell's law were conducted. The refractive indexes of solid DT are from 1.1618 ± 0.0002 to 1.1628 ± 0.0002 in the temperature range of 19.40 K to 17.89 K.

Effects of bulk impurity concentration on the reactivity of metal surface: sticking of hydrogen molecules and atoms to polycrystalline Nb containing oxygen.

Nonmetallic impurities segregated onto metal surfaces are able to drastically decrease the chemical reactivity of metals. In the present paper, effects of bulk impurities on the reactivity of metallic surfaces were investigated in a wide temperature range on an example of the sticking of hydrogen molecules and atoms to Nb [polycrystalline, with mainly (100)] containing solute oxygen. At all the investigated surface temperatures, T(S) (300-1400 K), we found the bulk oxygen concentration C(O) to have a strong effect on the integral probability, alpha(H(2) ), of dissociative sticking of H(2) molecules followed by hydrogen solution in the metal lattice: alpha(H(2) ) monotonically decreased by orders of magnitude with increasing C(O) from 0.03 to 1.5 at. %. The sticking coefficient alpha(H(2) ) was found to depend on T(S) but not on the gas temperature. The effect of C(O) on alpha(H(2) ) is explained by the presence of oxygen-free sites (holes in coverage) serving as active centers of the surface reaction in the oxygen monolayer upon Nb. In contrast to H(2) molecules, H atoms were found to stick to, and be dissolved in, oxygen-covered Nb with a probability comparable to 1, depending neither on C(O) nor on T(S). This proves that, unlike H(2) molecules, H atoms do stick to be dissolved mainly through regular surface sites covered by oxygen and not through the holes in coverage.