Intercalative and non-intercalative photo-recharge using all-solid-state cells for solar energy conversion and storage

Yoshimoto, Masataka*; Tamura, Kazuhisa; Watanabe, Kenta*; Shimizu, Keisuke*; Horisawa, Yuhei*; Kobayashi, Takeshi*; Tsurita, Hanae*; Suzuki, Kota*; Kanno, Ryoji*; Hirayama, Masaaki*

Sustainable Energy & Fuels (Internet), 8(6), p.1236 - 1244, 2024/03

https://doi.org/10.1039/D3SE01636F

Photo-rechargeable systems, which can efficiently convert and store solar energy into chemical energy within single devices, are essential to harness sunlight effectively. Photo-(de)intercalation plays a pivotal role in the functionality of photorechargeable systems. Nevertheless, the photo-(de)intercalation process has not been conclusively confirmed owing to potential interference from side reactions, such as the decomposition of liquid electrolytes and the elution of electrode materials. In this study, we successfully demonstrated photo-responsive Li-deintercalation using an all-solid-state thin-film battery comprised of epitaxially-grown anatase TiO doped with Nb (a-TiO:Nb) as the cathode. Under light irradiation, Li-deintercalation occurred and was subsequently reversibly intercalated into a-TiO:Nb during discharge.

Estimation of external dose for wild Japanese macaques captured in Fukushima prefecture; Decomposition of electron spin resonance spectrum

Mitsuyasu, Yusuke*; Oka, Toshitaka; Takahashi, Atsushi*; Kino, Yasushi*; Okutsu, Kenichi*; Sekine, Tsutomu*; Yamashita, Takuma*; Shimizu, Yoshinaka*; Chiba, Mirei*; Suzuki, Toshihiko*; et al.

Radiation Protection Dosimetry, 199(14), p.1620 - 1625, 2023/09

https://doi.org/10.1093/rpd/ncad146

We have been conducting dose assessments for Japanese macaques captured in Fukushima to reveal radiobiological effects on the low-dose expose animals. To accurately determine the external exposure dose, it is desirable to examine the analysis of the CO radical intensity. We examined ESR spectra of teeth of 10 macaques captured in Fukushima by two spectrum-decomposition algorithms.

Remnants of the nonrelativistic Casimir effect on the lattice

Nakayama, Katsumasa*; Suzuki, Kei

Physical Review Research (Internet), 5(2), p.L022054_1 - L022054_6, 2023/06

https://doi.org/10.1103/PhysRevResearch.5.L022054

The Casimir effect is a fundamental quantum phenomenon induced by the zero-point energy for a quantum field. It is well-known for relativistic fields with a linear dispersion relation, while its existence or absence for nonrelativistic fields with a quadratic dispersion is an unsettled question. Here, we investigate the Casimir effects for various dispersion relations on the lattice. We find that Casimir effects for dispersions proportional to an even power of momentum are absent in a long distance under some types of boundary conditions, while a remnant of the Casimir effect survives in a short distance. The concepts of such absence and remnants of Casimir effect help us to understand observables in finite-size materials with quantum fields on the lattice, such as thin films, narrow nanoribbons, and short nanowires. In terms of this effect, we also give a reinterpretation of the Casimir effect for massive fields.

Strong decays of singly heavy baryons from a chiral effective theory of diquarks

Kim, Y.*; Oka, Makoto; Suenaga, Daiki*; Suzuki, Kei

Physical Review D, 107(7), p.074015_1 - 074015_15, 2023/04

https://doi.org/10.1103/PhysRevD.107.074015

A chiral effective theory of scalar and vector diquarks is formulated, which is based on chiral symmetry and includes interactions between scalar and vector diquarks with one or two mesons. We find that the diquark interaction term with two mesons breaks the and flavor symmetries. To determine the coupling constants of the interaction Lagrangians, we investigate one-pion emission decays of singly heavy baryons (, and , , ), where baryons are regarded as diquark-heavy-quark two-body systems. Using this model, we present predictions of the unobserved decay widths of singly heavy baryons. We also study the change of masses and strong decay widths of singly heavy baryons under partial restoration of chiral symmetry.

Casimir effect for fermions on the lattice

Nakayama, Katsumasa*; Suzuki, Kei

Proceedings of Science (Internet), 430, p.379_1 - 379_9, 2023/04

https://doi.org/10.22323/1.430.0379

The conventional Casimir effect has been studied in the continuous spacetime, but to elucidate its counterpart in the lattice space is an important subject. Here, we discuss various types of Casimir effects for quantum fields on the lattice. By using a definition of the Casimir energy on the lattice, we show that the Casimir effect for the Wilson fermion is similar to that for the continuous Dirac fermion. We apply our definition to an effective Hamiltonian describing Dirac semimetals, such as CdAs and NaBi, and find an oscillatory behavior of the Casimir energy as a function of film thickness of semimetals. We also study contributions from Landau levels under magnetic fields and the Casimir effect for nonrelativistic particle fields on the lattice.

Magnonic Casimir effect in ferrimagnets

Nakata, Koki; Suzuki, Kei

Physical Review Letters, 130(9), p.096702_1 - 096702_6, 2023/03

https://doi.org/10.1103/PhysRevLett.130.096702

Quantum fluctuations of quantum fields induce a zero-point energy shift under spatial boundary conditions. This quantum phenomenon, called the Casimir effect, has been attracting much attention beyond the hierarchy of energy scales, whereas its application to spintronics has not yet been investigated enough, particularly to ferrimagnetic thin films. Here we fill this gap. Using the lattice field theory, we investigate the Casimir effect induced by quantum fields for magnons and find that the magnonic Casimir effect can arise not only in antiferromagnets but also in ferrimagnets (e.g., YIG). Thus, we pave the way for magnonic Casimir engineering.

Extraction properties of trivalent rare earth ions from nitric acid using a triamide-amine extractant

Uchino, Seiko*; Narita, Hirokazu*; Kita, Keisuke*; Suzuki, Hideya*; Matsumura, Tatsuro; Naganawa, Hirochika*; Sakaguchi, Koichi*; Oto, Keisuke*

Solvent Extraction Research and Development, Japan, 30(1), p.39 - 46, 2023/00

https://doi.org/10.15261/serdj.30.39

The extraction of trivalent rare earth ions (RE) from HNO solution using a triamide amine, tris(N,N-di-2-ethylhexyl-ethylamide)amine (DEHTAA), was conducted, and the extraction mechanism was estimated from extraction behavior of HNO and RE and the relationship between atomic number and extraction percentages (E%) for RE. A DEHTAA molecule dominantly formed a DEHTAA HNO at 1.0 M HNO and a DEHTAA(HNO) at 6.0 M HNO in the acid-equilibrated organic phase. This would provide the unique dependence of E% for the light RE on the HNO concentration, in which the E% value had a minimum and maximum at 0.5 M and 2 M HNO, respectively. The results of the slope analyses for the distribution ratios for RE suggested that the dominant RE complex was RE(NO)DEHTAA(DEHTAA HNO) at 1.0 M HNO. The E% for RE decreased from La to Lu at 1.0 M HNO; on the other hand, those increased from La to Nd at 0.25 M and from La to Sm and 6.0 M HNO.

Preliminary measurement of prompt gamma-ray from nuclear material for the classification of fuel debris and waste

Shiba, Tomooki; Kaburagi, Masaaki; Nomi, Takayoshi; Suzuki, Risa; Kosuge, Yoshihiro*; Nauchi, Yasushi*; Takada, Akira*; Nagatani, Taketeru; Okumura, Keisuke

Proceedings of International Topical Workshop on Fukushima Decommissioning Research (FDR2022) (Internet), 3 Pages, 2022/10

Detection limit of electron spin resonance for Japanese deciduous tooth enamel and density separation method for enamel-dentine separation

Oka, Toshitaka; Takahashi, Atsushi*; Koarai, Kazuma; Kino, Yasushi*; Sekine, Tsutomu*; Shimizu, Yoshinaka*; Chiba, Mirei*; Suzuki, Toshihiko*; Osaka, Ken*; Sasaki, Keiichi*; et al.

Journal of Radiation Research (Internet), 63(4), p.609 - 614, 2022/07

https://doi.org/10.1093/jrr/rrac033

Electron spin resonance (ESR) dosimetry is one of the most powerful tools for radiation dose reconstruction. The detection limit of this technique using human teeth is reported to be 56 mGy or 67 mGy; however, the absorbed dose of Fukushima residents after the Fukushima Daiichi Nuclear Power Plant (FNPP) accident was estimated to be lower than this detection limit. Our aim is to assess the absorbed radiation dose of children in Fukushima Prefecture after the accident; therefore, it is important to estimate the detection limit for their teeth. The detection limit for enamel of deciduous teeth of Japanese children separated by the mechanical method is estimated to be 115.0 mGy. The density separation method can effectively separate enamel from third molars of Japanese people. As we have collected thousands of teeth from children in Fukushima, the present technique may be useful to examine their external absorbed dose after the FNPP accident.

What is chiral susceptibility probing?

Aoki, Shinya*; Aoki, Yasumichi*; Fukaya, Hidenori*; Hashimoto, Shoji*; Rohrhofer, C.*; Suzuki, Kei

Proceedings of Science (Internet), 396, p.050_1 - 050_9, 2022/07

https://doi.org/10.22323/1.396.0050

In the early days of QCD, the axial anomaly was considered as a trigger for the breaking of the symmetry through topological excitations of gluon fields. However, it has been a challenge for lattice QCD to quantify the effect. In this work, we simulate QCD at high temperatures with chiral fermions. The exact chiral symmetry enables us to separate the contribution from the axial breaking from others among the susceptibilities in the scalar and pseudoscalar channels. Our result in two-flavor QCD indicates that the chiral susceptibility, which is conventionally used as a probe for breaking, is actually dominated by the axial breaking at temperatures MeV.