Hidehisa Hagiwara,Shintaro Ida, Tatsumi Ishihara

Abstract
Photocatalytic hydrogen production on graphitic carbon nitride (g-C₃N₄) from a hydrogen iodide (HI) aqueous solution was investigated with respect to light energy conversion. The photoabsorption and surface area of g-C₃N₄ depended strongly on the preparation temperature. The highest photocatalytic activity for HI decomposition was obtained with g-C₃N₄ prepared at 773 K, which had high photoabsorption capacity. This study revealed that the activity for I₂ formation on the g-C3N4 surface could be improved to achieve efficient HI decomposition with stoichiometric H₂ and I₂ formation.

Satoshi Akamaru, Mikako Murai, Masanori Hara

Abstract

In this paper, the hydrogen-controllable switch of electric circuits was proposed. The concept of the switch is based upon hydrogen gas pressure controlling the switch condition, either opened or closed, without any electrical supports. The switch has been designed so that it is closed in an atmosphere that does sot contain hydrogen. To study its switching behaviors, the switch was placed in the argon gas flow. When flowing gas was changed to a gas mixture containing 9% H₂ – 91%Ar, the switch was open after 201 s. However, when the mixture was replaced by argon gas, the switch was closed again. In addition, we determined that the threshold for hydrogen concentration while turning the switch on could be adjusted by an arranging a magnet in the switch.

Masanori Hara, Kana Kobayashi, Satoshi Akamaru, Masato Nakayama, Miki Shoji, Yoshinari Oshimi, Osamu Machida, Takuyo Yasumatsu

Abstract

When measuring the tritium concentration in environmental water by liquid scintillation counting, distillation of the water sample is indispensable. To investigate changes the tritium concentration during distillation, tritiated water was distilled under vacuum at around ambient temperature. During vacuum distillation, the tritium concentration in the residual sample water increased and that in the condensed sample water decreased. The change in the tritium concentration during the distillation process was explained by Rayleigh distillation model. When the volume of the condensed water sample was about 80 % of that of the original sample, its tritium concentration was about 97 % of that in the original sample. Therefore, water sample should be distilled above 80 % of sample water to keep an underestimation of tritium concentration within 3 %.