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Rajeev, H. S.*; Hu, X.*; Chen, W.-L.*; Zhang, D.*; Chen, T.*; 古府 麻衣子*; 梶本 亮一; 中村 充孝; Chen, A. Z.*; Johnson, G. C.*; et al.
Journal of the Physical Society of Japan, 94(3), p.034602_1 - 034602_14, 2025/03
被引用回数：0Two-dimensional hybrid organic-inorganic perovskites (HOIPs) have emerged as promising materials for light-emitting diode applications. In this study, by using time-of-flight neutron spectroscopy we identified and quantitatively separated the lattice vibrational and molecular rotational dynamics of two perovskites, butylammonium lead iodide (BA)
PbI
and phenethyl-ammonium lead iodide (PEA)PbI. By examining the corresponding temperature dependence, we found that the lattice vibrations, as evidenced by neutron spectra, are consistent with the lattice dynamics obtained from Raman scattering. We revealed that the rotational dynamics of organic molecules in these materials tend to suppress their photoluminescence quantum yield (PLQY) while the vibrational dynamics did not show predominant correlations with the same. Additionally, we observed photoluminescence emission peak splitting for both systems, which becomes prominent above certain critical temperatures where the suppression of PLQY begins. This study suggests that the rotational motions of polarized molecules may lead to a reduction in exciton binding energy or the breaking of degeneracy in exciton binding energy levels, enhancing non-radiative recombination rates, and consequently reducing photoluminescence yield. These findings offer a deeper understanding of fundamental interactions in 2D HOIPs and could guide the design of more efficient light-emitting materials for advanced technological applications.
都留 智仁; Han, S.*; Chen, Z.*; Lobzenko, I.; 乾 晴行*
まてりあ, 63(10), p.695 - 702, 2024/10
BCC相の代表的なハイエントロピー合金であるVNbMoTaWは、第5、第6周期の高融点金属で構成されており、それらの合金系の融点も高いことから高耐熱性(Refractory)ハイエントロピー合金と呼ばれている。VNbMoTaWとともにBCC相の代表的なハイエントロピー合金として知られているTiZrNbTaHfは同じく単相であり、VNbMoTaWに比べて融点は500
C低いものの、他のBCC合金に見られない室温以下の低温における優れた延性を示すことが知られている。VNbMoTaWとTiZrNbTaHfの二つの高耐熱性ハイエントロピー合金は、強度以外にもすべり挙動などの異なる特性を示すことが報告されているが、どのような特性が力学特性を支配しているかを理解することが、高温強度に優れかつ低温の延性を持つような高耐熱性合金などの優れた合金設計のためには不可欠である。VNbMoTaWとTiZrNbTaHfはいずれも単相合金であることを考えると、構成元素と転位などの変形の基礎となる特性の関係にその鍵があるはずである。本稿では、この二つの高耐熱性ハイエントロピー合金の力学特性の違いについて、実験、理論、計算機シミュレーションを駆使して、延性と強度を制御する重要な因子について検討した結果を紹介する。
archaea host diverse and interacting extrachromosomal elementsShi, L.-D.*; West-Roberts, J.*; Schoelmerich, M. C.*; Penev, P. I.*; Chen, L.-X.*; 天野 由記; Lei, S.*; Sachdeva, R.*; Banfield, J. F.*
Nature Microbiology (Internet), 9(9), p.2422 - 2433, 2024/09
被引用回数：1 パーセンタイル：0.00(Microbiology)Methane emissions that contribute to climate change can be mitigated by anaerobic methane-oxidizing archaea such as . Some have huge extrachromosomal genetic elements (ECEs) called Borgs that may modulate their activity, yet the broader diversity of ECEs is little studied. Here, we report small enigmatic linear ECEs, circular viruses and unclassified ECEs, that we predict replicate within . The linear ECEs have features such as inverted terminal repeats, pervasive tandem repeats, and coding patterns that are strongly reminiscent of Borgs, but they are only 52 kb to 145 kb in length. They share proteins with Borgs and . Thus, we refer to them as mini-Borgs. Mini-Borgs are genetically diverse and we assign them to at least five family-level groups. We also identify eight novel families of viruses, some of which encode multiheme cytochromes, and unclassified circular ECEs that encode TnpB genes. A population-heterogeneous CRISPR array is encoded in close proximity to TnpB and has spacers that target other ECEs including previously reported plasmids. The diverse groups of ECEs exchange genetic information with each other and with , likely impacting the activity and evolution of these environmentally important archaea.
Hu, F. F.*; Qin, T. Y.*; Ao, N.*; Su, Y. H.; Zhou, L.*; 徐 平光; Parker, J. D.*; 篠原 武尚; Chen, J.*; Wu, S. C.*
Engineering Fracture Mechanics, 306, p.110267_1 - 110267_18, 2024/08
被引用回数：2 パーセンタイル：65.22(Mechanics)Non-destructive and quantitative mapping of gradient residual strain distribution in surface-hardened railway S38C axles could provide a positive reference for determining service lifetime and maintenance strategy. To tackle this concern, time-of-flight neutron Bragg-edge transmission imaging was employed by real axle samples with and without impacted crater. A novel and simple procedure to formulate the residual strain field was also developed in this work, with the transmission batch code in Appendix A. By mapping the global two- dimensional residual strains, it can be verified that the residual strains into the axle are uniformly distributed in the hoop direction. Subsequently, it was revealed that the axial and hoop residual strains, respectively in the cylinder and the long strip samples prepared from a real S38C hollow axle, indicated a gradient evolution distribution with a depth of 
8 mm, covering a range of -5500 1000 
for axial strains and -6500 1000 for hoop strains. More importantly, the maximum compressive lattice strain of the cylinder sample was increased by 15.61%, and 22.35% at the impacting speeds of 100, and 125 m/s, respectively; and that of the long strip sample increased by 29.17%, and 43.70%, respectively. It can thus be concluded that lattice strains have redistributed around the impact crater, demonstrating the local alteration of the residual strain field. These new findings suggest the localized variation in residual strains should be taken into account while evaluating the service damage evolution of railway axles, especially those affected by high-speed impacts during operation.
Wang, S.*; Wang, J.*; Zhang, S.*; Wei, D.*; Chen, Y.*; Rong, X.*; Gong, W.; Harjo, S.; Liu, X.*; Jiao, Z.*; et al.
Journal of Materials Science & Technology, 185, p.245 - 258, 2024/06
被引用回数：13 パーセンタイル：98.32(Materials Science, Multidisciplinary)Nanoprecipitates and nanoscale retained austenite (RA) with suitable stability play crucial roles in determining the yield strength (YS) and ductility of ultrahigh strength steels (UHSSs). However, owing to the kinetics incompatibility between nanoprecipitation and austenite reversion, it is highly challenging to simultaneously introduce high-density nanoprecipitates and optimized RA in UHSSs. In this work, through the combination of austenite reversion treatment (ART) and subsequent flash austenitizing (FA), nanoscale chemical heterogeneity was successfully introduced into a low-cost UHSS prior to the aging process. This chemical heterogeneity involved the enrichment of Mn and Ni in the austenite phase. The resulting UHSS exhibited dual-nanoprecipitation of Ni(Al,Mn) and (Mo,Cr) C and nanoscale austenite stabilized via Mn and Ni enrichment. The hard martensitic matrix strengthened by high-density dual-nanoprecipitates constrains the plastic deformation of soft RA with a relatively low fraction, and the presence of relatively stable nanoscale RA with adequate Mn and Ni enrichment leads to a marginal loss in YS but keeps a persistent transformation-induced plasticity (TRIP) effect. As a result, the newly-developed UHSS exhibits an ultrahigh YS of 1.7 GPa, an ultimate tensile strength (UTS) of 1.8 GPa, a large uniform elongation (UE) of 8.5 percent, and a total elongation (TE) of 13 percent. The strategy of presetting chemical heterogeneity to introduce proper metastable phases before aging can be extended to other UHSSs and precipitation-hardened alloys.
Guo, B.*; Chen, H.*; Chong, Y.*; Mao, W.; Harjo, S.; Gong, W.; Zhang, Z.*; Jonas, J. J.*; 辻 伸泰*
Acta Materialia, 268, p.119780_1 - 119780_11, 2024/04
被引用回数：7 パーセンタイル：94.10(Materials Science, Multidisciplinary)This paper focused on the characterization and mechanism of the dynamic transformation from the alpha to beta phase during the hot deformation of Ti-6Al-4V alloy and pure titanium. The investigation employed in-situ neutron diffraction and atomistic simulations for a comprehensive understanding of the process. Dynamic transformations were observed during deformation of the Ti-6Al-4V alloy and pure titanium below the beta transus temperatures. During isothermal holding after unloading, the in-situ neutron diffraction results for Ti-6Al-4V and pure titanium indicated a sluggish reverse transformation from the beta to alpha phase. The mechanism of dynamic transformation was explored through in-situ neutron diffraction and atomistic simulations, which revealed twofold effects of deformation on dynamic transformation. Firstly, deformation led to a significant rise in the Gibbs energy of the alpha phase relative to the beta phase, expanding the beta phase region and diminishing the alpha phase region. Secondly, deformation lowered the energy barriers associated with dynamic transformation, facilitating the activation of dynamic transformation more readily than in the equilibrium state before deformation.
Linh, B. D.*; Corsi, A.*; Gillibert, A.*; Obertelli, A.*; Doornenbal, P.*; Barbieri, C.*; Duguet, T.*; G
mez-Ramos, M.*; Holt, J. D.*; Hu, B. S.*; et al.
Physical Review C, 109(3), p.034312_1 - 034312_15, 2024/03
被引用回数：1 パーセンタイル：63.95(Physics, Nuclear)理化学研究所RIビームファクトリーにて中性子過剰核
Arビームからの1中性子ノックアウト反応実験を行い、
Arのエネルギー準位および分光学的因子を導出した。特に、第一励起状態の
への分光学的因子が大きいことから、始状態のArの基底状態において中性子が
軌道を多く占めていることがわかった。これは、中性子数32がよい魔法数として知られる
Caとは異なった性質であり、カルシウムからアルゴンへと陽子が2個減ることで閉殻構造が大きく崩れることが明らかになった。
Shavers, M. R.*; Semones, E. J.*; Shurshakov, V.*; Dobynde, M.*; 佐藤 達彦; 込山 立人*; Tomi, L.*; Chen, J.*; El-Jaby, S.*; Straube, U.*; et al.
Journal of Medical Physics - Zeitschrift f
r medizinische Physik -, 34(1), p.31 - 43, 2024/02
本論文では、国際宇宙ステーションに協力している宇宙機関が、それぞれの評価方法で推定した宇宙線被ばく線量及びそのリスクを相互比較した結果を報告する。比較するミッションには、30日間の磁気圏外ミッションを選択し、宇宙線源として銀河宇宙線と太陽高エネルギー粒子の両方を考慮した。本比較結果より、各機関の線量・リスク評価方法に関する一貫性を確認することができた。本成果は、国際放射線防護委員会(ICRP)のタスクグループ115のレポートとして将来、まとめられる予定である。
Rhm, W.*; 伴 信彦*; Chen, J.*; Li, C.*; Dobynde, M.*; Durante, M.*; El-Jaby, S.*; 込山 立人*; 小笹 晃太郎*; 佐藤 達彦; et al.
Journal of Medical Physics - Zeitschrift fr medizinische Physik -, 34(1), p.4 - 13, 2024/02
国際放射線防護委員会(ICRP)は、過去90年間に渡って世界各国や国際的な放射線防護の枠組み作りに貢献してきた。2019年、ICRPは宇宙飛行士の放射線防護に関わる様々な問題に対応したタスクグループ(TG115)を立ち上げ、地上の放射線防護体系と宇宙の放射線防護体系との共通の枠組み作りに取り組んでいる。本論文では、現時点でICRPが定めている宇宙放射線防護体系についてとりまとめて報告する。
都留 智仁; Han, S.*; 松浦 周太郎*; Chen, Z.*; 岸田 恭輔*; Lobzenko, I.; Rao, S.*; Woodward, C.*; George, E.*; 乾 晴行*
Nature Communications (Internet), 15, p.1706_1 - 1706_10, 2024/02
被引用回数：25 パーセンタイル：98.58(Multidisciplinary Sciences)耐火ハイエントロピー合金(RHEA)は、超高温用途への応用の可能性から注目されている。しかし、体心立方結晶をもつため面心立方HEAよりも脆く、さらに、主要なNi基超合金やFCC合金系の材料よりも著しく低いクリープ強度を示す。これらの欠点を克服し、RHEAを実用的な構造材料に発展させるためには、強度と延性を制御する要因の基礎的な理解を深める必要がある。本研究では、TiZrHfNbTaとVNbMoTaWという2つのモデルRHEAを調査し、前者は77Kまで塑性圧縮可能であるのに対し、後者は298K以下では圧縮不可能であることを示した。TiZrHfNbTaの六方最密充填(HCP)元素は、すべての構成元素がBCCであるVNbMoTaWと比較して、転位芯エネルギーを下げ、格子歪みを大きくし、せん断弾性率を下げることで、高い延性と相対的に高い降伏強度につながることがわかった。転位芯構造はVNbTaMoWではコンパクトで、TiZrHfNbTaでは拡張しており、2つのRHEAで異なる滑り面が活性化していることがわかった。これらは、いずれもHCP元素の濃度に起因していることが第一原理計算により明らかになった。この結果は、HCP元素とBCC元素の比率に関連した電子構造の変化を利用して、強度、延性、すべり挙動を制御し、より効率的な発電所や輸送のための次世代高温材料を開発できることを実証している。
CoSi山内 宏樹; Sari, D. P.*; 安井 幸夫*; 坂倉 輝俊*; 木村 宏之*; 中尾 朗子*; 大原 高志; 本田 孝志*; 樹神 克明; 井川 直樹; et al.
Physical Review Research (Internet), 6(1), p.013144_1 - 013144_9, 2024/02
-Mn-type family alloys Mn
have three-dimensional antiferromagnetic (AFM) corner-shared triangular network. The antiferromagnet MnRhSi shows magnetic short-range order (SRO) over a wide temperature range of approximately 500 K above the N
el temperature 
= 190 K. MnCoSi has the smallest lattice parameter and the lowest in the family compounds. The quantum critical point (QCP) from AFM to the quantum paramagnetic state is expected near a cubic lattice parameter of 6.15 
of MnCoSi is only 140 K, quantum critical behavior is observed in MnCoSi as the enhancement of the electronic specific heat coefficient 
. We study how the magnetic SRO appears in MnCoSi by using neutron scattering, SR, and physical property measurements. The experimental results show that the neutron scattering intensity of the magnetic SRO does not change much regardless of the suppressed magnetic moment in the long-range magnetic ordered state compared to those of MnRhSi. The initial asymmetry drop ratio of SR above becomes small, and the magnetic SRO temperature 
is suppressed to 240 K. The results suggest that the MnCoSi is close to the QCP in the Mn system.
Zhang, A.*; Deng, K.*; Sheng, J.*; Liu, P.*; Kumar, S.*; 島田 賢也*; Jiang, Z.*; Liu, Z.*; Shen, D.*; Li, J.*; et al.
Chinese Physics Letters, 40(12), p.126101_1 - 126101_8, 2023/12
被引用回数：9 パーセンタイル：81.90(Physics, Multidisciplinary)In a Dirac semimetal, the massless Dirac fermion has zero chirality, leading to surface states connected adiabatically to a topologically trivial surface state as well as vanishing anomalous Hall effect. Recently, itis predicted that in the nonrelativistic limit of certain collinear antiferromagnets, there exists a type of chiral "Dirac-like" fermion, whose dispersion manifests four-fold degenerate crossing points formed by spin-degenerate linear bands, with topologically protected Fermi arcs. Here, by combining with neutron diffraction and first-principles calculations, we suggest a multidomain collinear antiferromagnetic configuration, rendering the existence of the Fermi-arc surface states induced by chiral Dirac-like fermions.
Be ground-state molecular structure using Be(
)
He triple differential reaction cross-section measurementsLi, P. J.*; Beaumel, D.*; Lee, J.*; Assi
, M.*; Chen, S.*; Franchoo, S.*; Gibelin, J.*; Hammache, F.*; Harada, T.*; 延与 佳子*; et al.
Physical Review Letters, 131(21), p.212501_1 - 212501_7, 2023/11
被引用回数：18 パーセンタイル：91.30(Physics, Multidisciplinary)Beのクラスター構造を()反応を用いて調査した。三重微分断面積が実験的に測定され、Tohsaki-Horiuchi-Schuck-R
pke波動関数の方法や反対称化分子動力学を用いた歪曲波インパルス近似計算と比較した。実験データと理論計算の顕著な一致が確認され、Beの比較的コンパクトな分子状態を確認した。
RhSi社本 真一; 山内 宏樹; 飯田 一樹*; 池内 和彦*; Hall, A. E.*; Chen, Y.-S.*; Lee, M. K.*; Balakrishnan, G.*; Chang, L.-J.*
Communications Physics (Internet), 6, p.248_1 - 248_6, 2023/09
被引用回数：2 パーセンタイル：42.04(Physics, Multidisciplinary)MnRhSi単結晶の中性子散乱測定により、局所スピン相関秩序がらせん構造を持つことがわかった。磁気クラスター形成の起源の可能性を、リフシッツ不変量とグリフィス相の観点から議論し、Co
ZnMn
の室温スキルミオン相とMnの非フェルミ液体挙動と比較した。
Yang, D. S.*; Wu, Y.*; Kanatzidis, E. E.*; Avila, R.*; Zhou, M.*; Bai, Y.*; Chen, S.*; 関根 由莉奈; Kim, J.*; Deng, Y.*; et al.
Materials Horizons, 10(11), p.4992 - 5003, 2023/09
被引用回数：12 パーセンタイル：0.00(Chemistry, Multidisciplinary)本論文では、ハード及びソフトハイブリッド材料システムでの3Dプリントによって形成されたマイクロ流体ネットワーク、統合バルブ、およびマイクロスケール光学キュベットにより、汗成分に対してその場で分光および蛍光分析した成果を紹介する。一連の試験により、これらのマイクロキュベットシステムが汗中の銅、塩化物、グルコースの濃度と汗のpHを実験室レベルの精度と感度で評価できることが実証された。
SnSeRen, Q.*; Gupta, M. K.*; Jin, M.*; Ding, J.*; Wu, J.*; Chen, Z.*; Lin, S.*; Fabelo, O.*; Rodriguez-Velamazan, J. A.*; 古府 麻衣子; et al.
Nature Materials, 22(8), p.999 - 1006, 2023/08
被引用回数：72 パーセンタイル：99.21(Chemistry, Physical)Ultralow thermal conductivity and fast ionic diffusion endow superionic materials with excellent performance both as thermoelectric converters and as solid-state electrolytes. Yet the correlation and interdependence between these two features remain unclear owing to a limited understanding of their complex atomic dynamics. Here we investigate ionic diffusion and lattice dynamics in argyrodite AgSnSe using synchrotron X-ray and neutron scattering techniques along with machine-learned molecular dynamics. We identify a critical interplay of the vibrational dynamics of mobile Ag and a host framework that controls the overdamping of low-energy Ag-dominated phonons into a quasi-elastic response, enabling superionicity. Concomitantly, the persistence of long-wavelength transverse acoustic phonons across the superionic transition challenges a proposed 'liquid-like thermal conduction' picture. Rather, a striking thermal broadening of low-energy phonons, starting even below 50 K, reveals extreme phonon anharmonicity and weak bonding as underlying features of the potential energy surface responsible for the ultralow thermal conductivity (
0.5 Wm
K) and fast diffusion. Our results provide fundamental insights into the complex atomic dynamics in superionic materials for energy conversion and storage.
Ca cast doubt on a doubly magic 
CaChen, S.*; Browne, F.*; Doornenbal, P.*; Lee, J.*; Obertelli, A.*; 角田 佑介*; 大塚 孝治*; 茶園 亮樹*; Hagen, G.*; Holt, J. D.*; et al.
Physics Letters B, 843, p.138025_1 - 138025_7, 2023/08
被引用回数：7 パーセンタイル：83.07(Astronomy & Astrophysics)
Scからの1陽子ノックアウト反応を用いて、
Caと
Caのガンマ崩壊を観測した。Caでは1456(12)keVの線遷移が、Caでは1115(34)keVの遷移が観測された。どちらの遷移も暫定的に
と割り当てられた。有効核子間相互作用をわずかに修正した広い模型空間での殻模型計算では、
準位エネルギー、2中性子分離エネルギー、反応断面積が実験とよく一致し、N=34閉殻の上に新しい殻が形成されていることを裏付けた。その構成要素である
と
軌道はほぼ縮退しており、これはCaが二重魔法核である可能性を排除し、Ca同位体のドリップラインを
Caあるいはそれ以上にまで広げる可能性がある。
Dong, F.*; Chen, S.*; 出町 和之*; 吉川 雅紀; 関 暁之; 高屋 茂
Nuclear Engineering and Design, 404, p.112161_1 - 112161_15, 2023/04
被引用回数：20 パーセンタイル：99.14(Nuclear Science & Technology)To ensure nuclear safety, timely and accurate anomaly detection is of utmost importance in the daily condition monitoring of Nuclear Power Plants (NPPs), as any slight anomaly in a plant may result in an irreversible and serious accident, as well as high costs of maintenance and management. Nevertheless, due to the unique inherent attributes of anomalies, the difficulty of automatic detection in NPPs is increased. Previous model-driven anomaly detection approaches required skilled priori knowledge, leading to their limited usability. Commonly adopted deep learning-based data-driven anomaly detection approaches may not easily acquire the most relevant features when dealing with sensor data containing redundant information with uneven distribution of anomalies. To alleviate these issues, this paper propose an attention-based time series model for anomaly detection to ensure safety in NPPs. First, we employ one-dimension convolutional neural network (1D-CNN) backbone for feature extraction to preserve original inherent features of time series inputs. Subsequently, we originally adopt soft-attention mechanism to automatically extract the most relevant temporal features considering the specificity of anomaly detection in NPPs. The performance of the proposed model was experimentally validated on the High Temperature Gas-cooled Reactor (HTGR) anomaly case dataset simulated using the analytical code. The experimental results indicate that the proposed model was capable of detecting anomalies in NPPs with superior performance to the baseline model, while ensuring fast detection at short time steps.
Chen, J.*; 山本 慧; Zhang, J.*; Ma, J.*; Wang, H.*; Sun, Y.*; Chen, M.*; Liu, S.*; Gao, P.*; Yu, D.*; et al.
Physical Review Applied (Internet), 19(2), p.024046_1 - 024046_9, 2023/02
被引用回数：6 パーセンタイル：66.92(Physics, Applied)Coherent coupling in magnon based hybrid system has many potential applications in quantum information processing. Magnons can propagate in magnetically ordered materials without any motion of electrons, offering a unique method to build low-power-consumption devices and information channels free of heat dissipation. In this article, we demonstrate the coherent propagation of hybridized modes between spin waves and Love surface acoustic waves in a multiferroic BiFeO and ferromagnetic La
Sr
MnO based heterostructure. The magneto-elastic coupling enables a giant enhancement of strength of the hybridized mode by a factor of 26 compared to that of the pure spin waves. A short wavelength down to 250 nm is demonstrated for the hybridized mode, which is desirable for nanoscale acousto-magnonic applications. Our combined experimental and theoretical analyses represent an important step towards the coherent control in hybrid magnonics, which may inspire the study of magnon-phonon hybrid systems for coherent information processing and manipulation.
phase to phase in zirconium alloy revealed by in-situ neutron diffraction during high temperature deformationGuo, B.*; Mao, W.; Chong, Y.*; 柴田 曉伸*; Harjo, S.; Gong, W.; Chen, H.*; Jonas, J. J.*; 辻 伸泰*
Acta Materialia, 242, p.118427_1 - 118427_11, 2023/01
被引用回数：12 パーセンタイル：71.25(Materials Science, Multidisciplinary)Dynamic transformation from alpha (HCP) to beta (BCC) phase in a zirconium alloy was revealed by the use of in-situ neutron diffraction during hot compression. The dynamic transformation was unexpectedly detected during isothermal compression at temperatures of 900C and 950C (alpha + beta two-phase region) and strain rates of 0.01 s and 0.001 s, even though equilibrium two-phase states were achieved prior to the hot compression. Dynamic transformation was accompanied by diffusion of Sn from beta to alpha phase, which resulted in changes of lattice parameters and a characteristic microstructure of alpha grains. The details of dynamic transformation are discussed using the evolution of lattice constants.
