Enhancement of hydrogen response by forming an Au submonolayer on nanogap Pd nanoparticles

Nakamura Nobutomo, Yoshikawa Kazushi, Ishii Akio. Applied Physics Letters 125, 021902 (2024) https://doi.org/10.1063/5.0204024.When Pd nanoparticles dispersed on a glass substrate with nanometer order gaps are exposed to H2 gas, H atoms are adsorbed on the nanoparticle surface, and the electrical resistance between the nanoparticles increases because of the tunneling current suppression. In contrast, when Au nanoparticles are exposed to H2 gas, the resistance remains unchanged because H atoms are not adsorbed on the Au surface. Considering these behaviors, the change ratio of the electrical resistance is expected to be smaller when the surface of Pd nanoparticles is partially covered with Au. However, the experimental results show the opposite resistance change. Density functional theory simulation indicates that H atoms are adsorbed and absorbed on the pure Pd surface, but H atoms are adsorbed and tend to remain on the partially covered Pd surface. These results indicate that the decrease in the resistance due to the gap narrowing by hydrogen absorption occurs in Pd nanoparticles, but it does not occur in Au/Pd nanoparticles, resulting in a larger resistivity increase compared with the Pd nanoparticles. This result implies that in certain cases, the low reactivity of Au to H2 contributes to the enhancement of the electrical resistance response

Time domain Sound Field Analysis Using the Finite Element Method and the Fast Multipole Boundary Element Method

This paper presents a noise evaluation system based on acoustic wave theory. This paper utilizes two methods – the finite element method and the boundary element method using a fast multipole method, and compares the numerical results of the benchmark problem. In addition, we show the results using the analytical model of the complex shape based on standard specifications of noise barriers and discuss the difference of the numerical results and auralization results between the two methods

Development of Microsatellite Markers for the Two Giant Salamander Species (Andrias japonicus and A. davidianus)

The Japanese giant salamander (Andrias japonicus) is a near threatened species endemic to western Japan and is strictly protected by law. However, available information regarding the genetic diversity and genetic structure in this species, essential for its effective conservation, has been limited. We developed four microsatellite markers from A. japonicus and characterized these markers for two populations of this species, as well as for some captive Chinese giant salamanders (A. davidianus) of unknown original locality or localities. These markers, showing expected heterozygosities of 0. 00–0. 50 in the former and 0. 63–0. 89 in the latter, will be useful in documenting population genetic properties for each of the two species