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論文

Strong low-energy rattling modes enabled liquid-like ultralow thermal conductivity in a well-ordered solid

Liu, P.-F.*; Li, X.*; Li, J.*; Zhu, J.*; Tong, Z.*; 古府 麻衣子*; 楡井 真実; Xu, J.*; Yin, W.*; Wang, F.*; et al.

National Science Review, 11(12), p.nwae216_1 - nwae216_10, 2024/12

https://doi.org/10.1093/nsr/nwae216
 被引用回数：12 パーセンタイル：91.22(Multidisciplinary Sciences)

Crystalline solids exhibiting inherently low lattice thermal conductivity ($$kappa_{rm L}$$) are of great importance in applications such as thermoelectrics and thermal barrier coatings. However, $$kappa_{rm L}$$ cannot be arbitrarily low and is limited by the minimum thermal conductivity related to phonon dispersions. In this work, we report the liquid-like thermal transport in a well-ordered crystalline CsAg$$_5$$Te$$_3$$, which exhibits an extremely low $$kappa_{rm L}$$ value of $$sim$$ 0.18 Wm$$^{-1}$$K$$^{-1}$$. On the basis of first-principles calculations and inelastic neutron scattering measurements, we find that there are lots of low-lying optical phonon modes at $$sim$$ 3.1 meV hosting the avoided-crossing behavior with acoustic phonons. These strongly localized modes are accompanied by weakly bound rattling Ag atoms with thermally induced large amplitudes of vibrations. Using the two-channel model, we demonstrate that coupling of the particle-like phonon modes and the heat-carrying wave-like phonons is essential for understanding the low $$kappa_{rm L}$$, which is heavily deviated from the $$1/T$$ temperature dependence of the standard Peierls theory. In addition, our analysis indicates that the soft structural framework with liquid-like motions of the fluctuating Ag atoms is the underlying cause that leads to the suppression of the heat conduction in CsAg$$_5$$Te$$_3$$. These factors synergistically account for the ultralow $$kappa_{rm L}$$ value. Our results demonstrate that the liquid-like heat transfer could indeed exist in a well-ordered crystal.

論文

Brightening triplet excitons enable high-performance white-light emission in organic small molecules via integrating n-$$pi^*/pi$$-$$pi^*$$ transitions

Yang, Q.*; Yang, X.*; Wang, Y.*; Fei, Y.*; Li, F.*; Zheng, H.*; Li, K.*; Han, Y.*; 服部 高典; Zhu, P.*; et al.

Nature Communications (Internet), 15, p.7778_1 - 7778_9, 2024/09

https://doi.org/10.1038/s41467-024-52196-7
 被引用回数：9 パーセンタイル：88.46(Multidisciplinary Sciences)

明るい一重項励起子と三重項励起子を同時に発現する発光材料は、オプトエレクトロニクス、サイネージ、情報暗号化において大きな可能性を秘めている。しかしながら、高性能の白色発光を実現するためには、蛍光と燐光の寄与が不均衡であることが大きな障害となっている。ここでは、水素結合の協同効果による圧力処理エンジニアリングによって、n-$$pi^*/pi$$-$$pi^*$$遷移の混合を実現し、イソフタル酸(IPA)中で三重項状態の発光を7%から40%に高めることで、この課題に対処した。加圧処理したIPAでは、蛍光と燐光のハイブリッドに基づく優れた白色発光が得られ、フォトルミネッセンス量子収率は当初の19%(青色発光)から75%に増加した。その場での高圧IRスペクトル、X線回折、中性子回折から、圧力の上昇に伴い水素結合が連続的に強化されることが明らかになった。さらに、この強化された水素結合は、圧力処理後も常圧条件下まで保持され、バランスの取れた一重項/三重項励起子集団のための効率的な系間交差を目的としたIPAに与え、効率的な白色発光をもたらした。この研究は、有機低分子の三重項状態を明るくするルートを提案するだけでなく、一重項励起子と三重項励起子の比率を調節して、高性能の白色発光を構築するものである。

論文

Antiferromagnetism and phase stability of CrMnFeCoNi high-entropy alloy

Zhu, L.*; He, H.*; Naeem, M.*; Sun, X.*; Qi, J.*; Liu, P.*; Harjo, S.; 中島 健次; Li, B.*; Wang, X.-L.*

Physical Review Letters, 133(12), p.126701_1 - 126701_6, 2024/09

https://doi.org/10.1103/PhysRevLett.133.126701
 被引用回数：1 パーセンタイル：48.32(Physics, Multidisciplinary)

It has long been suspected that magnetism could play a vital role in the phase stability of multi- component high-entropy alloys. However, the nature of the magnetic order, if any, has remained elusive. Here, by using elastic and inelastic neutron scattering, we demonstrate evidence of antiferromagnetic order below $$sim$$80 K and strong spin fluctuations persisting to room temperature in a single-phase face-centered cubic (fcc) CrMnFeCoNi high-entropy alloy. Despite the chemical complexity, the magnetic structure in CrMnFeCoNi can be described as $$gamma$$-Mn-like, with the magnetic moments confined in alternating (001) planes and pointing toward the $$langle$$111$$rangle$$ direction. Combined with first-principles calculation results, it is shown that the antiferromagnetic order and spin fluctuations help stabilized the fcc phase in CrMnFeCoNi high-entropy alloy.

論文

Signatures of Kitaev interactions in the van der Waals ferromagnet VI$$_{3}$$

Gu, Y. Q.*; Gu, Y. M.*; Liu, F.*; 河村 聖子; 村井 直樹; Zhao, J.*

Physical Review Letters, 132(24), p.246702_1 - 246702_7, 2024/06

https://doi.org/10.1103/PhysRevLett.132.246702
 被引用回数：2 パーセンタイル：48.32(Physics, Multidisciplinary)

Materials manifesting the Kitaev model, characterized by bond-dependent interactions on a honeycomb lattice, can host exotic phenomena like quantum spin liquid states and topological magnetic excitations. However, finding such materials remains a formidable challenge. Here, we report high-resolution inelastic neutron scattering measurements performed on VI$$_{3}$$, a van der Waals ferromagnetic Mott insulator, covering a wide range of reciprocal space. Our measurements unveil highly anisotropic magnetic excitations in momentum space. Through a comprehensive comparative analysis of various models that incorporate diverse symmetry-allowed magnetic interactions, we find the observed excitations are well captured by a model with a large bond-dependent Kitaev interaction. These results not only help to understand the intriguing properties of VI$$_{3}$$, such as the pronounced anomalous thermal Hall effects and strong pressure or structure dependence of magnetism, but also open a new avenue for exploring Kitaev physics.

論文

Onset of collectivity for argon isotopes close to $$N=32$$

Linh, B. D.*; Corsi, A.*; Gillibert, A.*; Obertelli, A.*; Doornenbal, P.*; Barbieri, C.*; Duguet, T.*; G$'o$mez-Ramos, M.*; Holt, J. D.*; Hu, B. S.*; et al.

Physical Review C, 109(3), p.034312_1 - 034312_15, 2024/03

https://doi.org/10.1103/PhysRevC.109.034312
 被引用回数：2 パーセンタイル：58.81(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$$^{50}$$Arビームからの1中性子ノックアウト反応実験を行い、$$^{49}$$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$$1/2^-$$への分光学的因子が大きいことから、始状態の$$^{50}$$Arの基底状態において中性子が$$p_{1/2}$$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$$^{52}$$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。

論文

Chiral Dirac fermion in a collinear antiferromagnet

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

https://doi.org/10.1088/0256-307X/40/12/126101
 被引用回数：11 パーセンタイル：83.08(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.

論文

Petrophysical properties of representative geological rocks encountered in carbon storage and utilization

Hu, Q.*; Wang, Q. M.*; Zhang, T.*; Zhao, C.*; Iltaf, K. H.*; Liu, S. Q.*; 深津 勇太

Energy Reports (Internet), 9, p.3661 - 3682, 2023/12

https://doi.org/10.1016/j.egyr.2023.02.020
 被引用回数：10 パーセンタイル：66.70(Energy & Fuels)

This study evaluates petrophysical properties of representative geological rocks in the context of injectivity, storage space, and caprock integrity for effective utilization and long-term storage of carbon dioxide. A total of 10 geological rocks were selected as representative storage media for consideration as saline aquifers & depleted oil and gas reservoirs, basalts, and cap rocks, as well as utilization in organic-rich shale and coal seams. An integrated suite of laboratory tests, including liquid immersion porosimetry, gas expansion porosimetry, grain size distribution, mercury intrusion porosimetry, and gas diffusion, were performed on these various rock samples. The results exhibit a disparity of petrophysical properties among two broad groups of rocks: rocks selected for possible storage of CO$$_{2}$$ have porosities of $$sim$$10-25%, permeabilities of $$sim$$10$$^{-16}$$-10$$^{-13}$$ m$$^{2}$$, $$mu$$m-sized pore-throat size distribution, and mostly good pore connectivity; in contrast, the potential caprocks have porosities of $$sim$$0.5-5%, permeabilities of $$sim$$10$$^{-20}$$-10$$^{-18}$$ m$$^{2}$$, pore throat sizes of $$<$$50 nm, and probably poorly connected pore networks. An understanding of the measured facets of pore structure and contribution of fractures is also critical in the context of different testing principles and data interpretation of petrophysical analyses, as well as observational scales in the laboratory and field, and therefore reliable confidence of CO$$_{2}$$ storage and utilization performance. Our work further illustrates the controlling influence of grain size distribution and geological processes on pore size distribution and pore connectivity for a wide range of rock types and lithologies, and particularly presents the extent and behavior of CO$$_{2}$$ gas diffusion with a custom-designed apparatus for a holistic understanding of various petrophysical attributes of widely different geological rocks.

論文

Validation of the $$^{10}$$Be ground-state molecular structure using $$^{10}$$Be($$p,palpha$$)$$^{6}$$He triple differential reaction cross-section measurements

Li, P. J.*; Beaumel, D.*; Lee, J.*; Assi$'e$, 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

https://doi.org/10.1103/PhysRevLett.131.212501
 被引用回数：21 パーセンタイル：93.59(Physics, Multidisciplinary)

$$^{10}$$Beのクラスター構造を($$p,palpha$$)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$"o$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、$$^{10}$$Beの比較的コンパクトな分子状態を確認した。

論文

Level structures of $$^{56,58}$$Ca cast doubt on a doubly magic $$^{60}$$Ca

Chen, 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

https://doi.org/10.1016/j.physletb.2023.138025
 被引用回数：9 パーセンタイル：85.35(Astronomy & Astrophysics)

$$^{57,59}$$Scからの1陽子ノックアウト反応を用いて、$$^{56}$$Caと$$^{58}$$Caのガンマ崩壊を観測した。$$^{56}$$Caでは1456(12)keVの$$gamma$$線遷移が、$$^{58}$$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$$2^{+}_{1} rightarrow 0^{+}_{gs}$$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、$$2^{+}_{1}$$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$$0_{f5/2}$$と$$0_{g9/2}$$軌道はほぼ縮退しており、これは$$^{60}$$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$$^{70}$$Caあるいはそれ以上にまで広げる可能性がある。

論文

Pressure-modulated magnetism and negative thermal expansion in the Ho$$_2$$Fe$$_{17}$$ intermetallic compound

Cao, Y.*; Zhou, H.*; Khmelevskyi, S.*; Lin, K.*; Avdeev, M.*; Wang, C.-W.*; Wang, B.*; Hu, F.*; 加藤 健一*; 服部 高典; et al.

Chemistry of Materials, 35(8), p.3249 - 3255, 2023/04

https://doi.org/10.1021/acs.chemmater.3c00158
 被引用回数：2 パーセンタイル：21.90(Chemistry, Physical)

静水圧や化学圧力は、結晶構造を変化させる効率的な刺激であり、材料科学において電気的、磁気的特性のチューニングによく利用されている。しかし、化学圧力は定量化が困難であり、これら両者の定量的な対応関係はまだよくわかっていない。本研究では、負の熱膨張(NTE)を持つ永久磁石の候補である金属間化合物を調べた。放射光X線その場観察により、AlをドープしたHo$$_2$$Fe$$_{17}$$に負の化学圧力があることを明らかにし、単位セル体積の温度・圧力依存性を用いそれを定量的に評価した。また、磁化測定と中性子回折測定を組み合わせることで、磁気秩序に対する化学圧力と静水圧の違いを比較した。興味深いことに、圧力はNTEの抑制と増強を制御するために使用することができた。電子状態計算から、圧力がFermiレベル(EF)に対する主要バンドの上部に影響を与えたことを示しており、これは磁気安定性に影響を与え、それが磁気とNTEを調節する上で重要な役割を果たしていることがわかった。本研究は、圧力の影響を理解し、それを利用して機能性材料の特性を制御する良い例を示している。

論文

Multiple mechanisms in proton-induced nucleon removal at $$sim$$100 MeV/nucleon

Pohl, T.*; Sun, Y. L.*; Obertelli, A.*; Lee, J.*; G$'o$mez-Ramos, M.*; 緒方 一介*; 吉田 数貴; Cai, B. S.*; Yuan, C. X.*; Brown, B. A.*; et al.

Physical Review Letters, 130(17), p.172501_1 - 172501_8, 2023/04

https://doi.org/10.1103/PhysRevLett.130.172501
 被引用回数：12 パーセンタイル：88.25(Physics, Multidisciplinary)

大きなフェルミ面非対称性を持つ陽子過剰な$$^{14}$$O原子核からの100MeV/nucleonでの陽子による陽子・中性子除去反応について報告した。この結果は、quasi-freeノックアウト反応、非弾性散乱、核子移行反応を含む複数の反応機構の定量的寄与を初めて示すものである。このようなエネルギー領域では通常無視される非弾性散乱と核子移行の寄与が、弱束縛陽子と強束縛中性子の除去反応断面積にそれぞれ約50%と30%寄与していることが示された。

論文

Corrosion fatigue crack growth behavior of a structurally gradient steel for high-speed railway axles

Ao, N.*; Zhang, H.*; Xu, H. H.*; Wu, S. C.*; Liu, D.*; 徐 平光; Su, Y. H.; Kang, Q. H.*; Kang, G. Z.*

Engineering Fracture Mechanics, 281, p.109166_1 - 109166_14, 2023/03

https://doi.org/10.1016/j.engfracmech.2023.109166
 被引用回数：12 パーセンタイル：83.88(Mechanics)

Considering the complex service environments that high-speed railway axles are subjected to, the fatigue crack growth (FCG) behavior of a structurally gradient axle steel with different pre-crack depths both in air and corrosive medium was investigated at a frequency of 5 Hz. The results indicated that in the high $$Delta$$$$K$$ region, FCG rate was dramatically accelerated by corrosion, but the gap narrows as $$Delta$$$$K$$ decreased. The accelerated corrosion FCG rate was a comprehensive result of the acceleration effect of the anodic dissolution, hydrogen-enhanced localized plasticity and the retardation effect of corrosion-induced crack-tip blunting. Despite the fact that the corrosion resistance gradually decreased as the pre-crack depth increased, the FCG rate in the corrosive medium gradually decreased. This was because fatigue loading played a more important role than corrosion in accelerating the corrosion FCG rate.

論文

"Southwestern" boundary of the $$N = 40$$ island of inversion; First study of low-lying bound excited states in $$^{59}$$V and $$^{61}$$V

Elekes, Z.*; Juh$'a$sz, M. M.*; Sohler, D.*; Sieja, K.*; 吉田 数貴; 緒方 一介*; Doornenbal, P.*; Obertelli, A.*; Achouri, N. L.*; 馬場 秀忠*; et al.

Physical Review C, 106(6), p.064321_1 - 064321_10, 2022/12

https://doi.org/10.1103/PhysRevC.106.064321
 被引用回数：3 パーセンタイル：32.42(Physics, Nuclear)

$$^{59}$$Vと$$^{61}$$Vの低励起準位構造を初めて探索した。$$^{61}$$Vについては中性子ノックアウト反応と陽子非弾性散乱が、$$^{59}$$Vについては中性子ノックアウト反応データが得られた。$$^{59}$$Vについては4つ、$$^{61}$$Vについては5つの新たな遷移が確認された。Lenzi-Nowacki-Poves-Sieja (LNPS)相互作用に基づく殻模型計算との比較によって、それぞれの同位体について確認されたガンマ線のうち3つが、first 11/2$$^{-}$$状態とfirst 9/2$$^{-}$$状態からの崩壊と決定された。$$^{61}$$Vについては、($$p$$,$$p'$$)非弾性散乱断面積は四重極変形と十六重極変形を想定したチャネル結合法により解析されたが、十六重極変形の影響により、明確に反転の島に属するとは決定できなかった。

論文

Extended $$p_{3/2}$$ neutron orbital and the $$N = 32$$ shell closure in $$^{52}$$Ca

Enciu, M.*; Liu, H. N.*; Obertelli, A.*; Doornenbal, P.*; Nowacki, F.*; 緒方 一介*; Poves, A.*; 吉田 数貴; Achouri, N. L.*; 馬場 秀忠*; et al.

Physical Review Letters, 129(26), p.262501_1 - 262501_7, 2022/12

https://doi.org/10.1103/PhysRevLett.129.262501
 被引用回数：18 パーセンタイル：84.65(Physics, Multidisciplinary)

$$sim$$230MeV/nucleonでの$$^{52}$$Caからの中性子ノックアウト反応が$$gamma$$線分光と行われ、$$1f_{7/2}$$と$$2p_{3/2}$$軌道からの中性子ノックアウト反応の運動量分布が測定された。断面積は$$N=32$$の閉殻と整合し、Ca同位体での$$N=28$$と$$N=34$$閉殻と同程度に強い閉殻であることが確認された。運動量分布の分析から$$1_{f7/2}$$と$$2p_{3/2}$$軌道の平均二乗根半径の差は0.61(23)fmと決定され、これはmodified-shell-modelによる予言の0.7fmと整合した。これは、中性子過剰なCa同位体での$$2p_{3/2}$$軌道半径が大きいことが、中性子数にしたがって線形的に荷電半径が増える意外な現象の原因であることを示唆している。

論文

Two-dimensional quantum universality in the spin-1/2 triangular-lattice quantum antiferromagnet Na$$_{2}$$BaCo(PO$$_{4}$$)$$_{2}$$

Sheng, J.*; Wang, L.*; Candini, A.*; Jiang, W.*; Huang, L.*; Xi, B.*; Zhao, J.*; Ge, H.*; Zhao, N.*; Fu, Y.*; et al.

Proceedings of the National Academy of Sciences of the United States of America, 119(51), p.e2211193119_1 - e2211193119_9, 2022/12

https://doi.org/10.1073/pnas.2211193119
 被引用回数：30 パーセンタイル：93.24(Multidisciplinary Sciences)

Although considerable progress has been made in the theoretical understanding of the low-dimensional frustrated quantum magnets, experimental realizations of a well-established scaling analysis are still scarce. This is particularly true for the two-dimensional antiferromagnetic triangular lattices. Owing to the small exchange strength, the newly discovered compound Na$$_{2}$$BaCo(PO$$_{4}$$)$$_{2}$$ provides a rare opportunity for clarifying the quantum criticality in an ideal triangular lattice with quantum spin S=1/2. In addition to the establishment of the complete phase diagrams, the spin Hamiltonian with a negligible interplane interaction has been determined through the spin wave dispersion in the polarized state, which is consistent with the observation of a two-dimensional quantum critical point with the Bose-Einstein condensation of diluted free bosons.

論文

First observation of the decay of the 13/2$$^+$$ isomer in $$^{183}$$Hg and $$B$$(${it M}$2) systematics of neutron transitions across the nuclear chart

Huang, H.*; Zhang, W. Q.*; Andreyev, A. N.; Liu, Z.*; Seweryniak, D.*; Li, Z. H.*; Guo, C. Y.*; Barzakh, A. E.*; Van Duppen, P.*; Andel, B.*; et al.

Physics Letters B, 833, p.137345_1 - 137345_8, 2022/10

https://doi.org/10.1016/j.physletb.2022.137345
 被引用回数：1 パーセンタイル：18.16(Astronomy & Astrophysics)

The decay of the 13/2$$^+$$ isomeric state in $$^{183}$$Hg was observed for the first time following the $$alpha$$ decay of the 13/2$$^+$$ isomer in $$^{187}$$Pb produced in the $$^{142}$$Nd$$(^{50}$$Cr$$, 2p3n)$$ reaction. Using $$alpha$$-$$gamma$$ delayed coincidence measurements, the half-life of this isomer was measured to be 290(30) $$mu$$s. This isomer is proposed to deexcite by an unobserved low-energy $$M$$2 transition to the known 9/2$$^-$$ member of a strongly prolate-deformed 7/2$$^-$$[514] band, followed by a 105-keV $$M$$1 transition to the bandhead. A lower limit of B($$M$$2)$$geq$$0.018 W.u. was deduced for the unobserved transition. The presumed retardation is proposed to be due to the notable shape change between the initial, nearly spherical, and the final, strongly deformed, states. A similar scenario is also considered for the 13/2$$^+$$ isomer in $$^{181}$$Hg, suggesting both are cases of shape isomers. The B($$M$$2) systematics of neutron transitions across the nuclear chart is discussed.

論文

Synergistic hybrid electrocatalysts of platinum alloy and single-atom platinum for an efficient and durable oxygen reduction reaction

Liu, B.*; Feng, R.*; Busch, M.*; Wang, S.*; Wu, H.*; Liu, P.*; Gu, J.*; Bahadoran, A.*; 松村 大樹; 辻 卓也; et al.

ACS Nano, 16(9), p.14121 - 14133, 2022/09

https://doi.org/10.1021/acsnano.2c04077
 被引用回数：97 パーセンタイル：98.70(Chemistry, Multidisciplinary)

Pt single-atom materials possess an ideal atom economy but suffer from limited intrinsic activity and side reaction of producing H$$_{2}$$O$$_{2}$$ in catalyzing the oxygen reduction reaction (ORR). Here, we demonstrate that anchoring platinum alloys on single-atom Pt-decorated carbon (Pt- SAC) surmounts their inherent deficiencies, thereby enabling a complete four-electron ORR pathway catalysis with high efficiency and durability. Pt$$_{3}$$Co@Pt-SAC demonstrates an exceptional mass and specific activities 1 order of magnitude higher than those of commercial Pt/C. They are durable throughout 50000 cycles, showing only a 10 mV decay in halfwave potential. The superior durability is attributed to the shielding effect of the Pt-SAC coating, which significantly mitigates the dissolution of Pt$$_{3}$$Co cores.

論文

Identification of excited states in $$^{188}$$Bi and $$^{188}$$Po

Zhang, W. Q.*; Andreyev, A. N.; Liu, Z.*; Seweryniak, D.*; Huang, H.*; 他37名*

Physical Review C, 106(2), p.024317_1 - 024317_11, 2022/08

https://doi.org/10.1103/PhysRevC.106.024317
 被引用回数：4 パーセンタイル：53.47(Physics, Nuclear)

The neutron-deficient $$^{188}$$Bi and $$^{188}$$Po isotopes have been studied by $$gamma$$-ray spectroscopy using the recoil-decay tagging technique with the Argonne Gas-Filled Analyzer. A new 0.25(5)-micro second isomeric state and a prompt cascade formed by 319-, 366-, and 462-keV $$gamma$$ rays have been established on top of the (10$$^{-}$$) $$alpha$$-decaying isomer in $$^{188}$$Bi. The first excited (2$$^{+}$$) state in $$^{188}$$Po was identified, its excitation energy of 242(2) keV continues the nearly constant trend for the first 2$$^{+}$$ states in $$^{190,192,194}$$Po. The state is most likely a member of a prolate rotational band built on the ground state, albeit mixing with other coexisting configurations cannot be excluded. The new results obtained in the present work provide new information to shape coexistence in bismuth and polonium isotopes near the neutron midshell at $$N$$ = 104. In this mass region, a reduction in the prompt $$gamma$$-ray yield obtained with recoil decay tagging was observed for a few nuclides, and the possible reasons are presented.

論文

First observation of a shape isomer and a low-lying strongly-coupled prolate band in neutron-deficient semi-magic $$^{187}$$Pb

Zhang, W. Q.*; Andreyev, A. N.; Liu, Z.*; Seweryniak, D.*; Huang, H.*; Li, Z. H.*; Li, J. G.*; Guo, C. Y.*; 他34名*

Physics Letters B, 829, p.137129_1 - 137129_7, 2022/06

https://doi.org/10.1016/j.physletb.2022.137129
 被引用回数：6 パーセンタイル：67.20(Astronomy & Astrophysics)

Prompt and delayed $$gamma$$-ray spectroscopy of the neutron-deficient, semi-magic isotope $$^{187}$$Pb has been performed at the Argonne Gas-Filled Analyzer. A new 5.15(15)-$$mu$$s isomeric state at only 308 keV above the spherical 3/2$$^{-}$$ ground state is identified and classified as a shape isomer. A strongly-coupled band is observed on top of the isomer, which is nearly identical to the one built on the prolate 7/2$$^{-}$$[514] Nilsson state in the isotone $$^{185}$$Hg. Based on this similarity and on the result of the potential-energy surface calculations, the new isomer in $$^{187}$$Pb is proposed to originate from the same configuration. The retarded character of the 308-keV transition can be well explained by the significant difference between the prolate parent and spherical daughter configurations, leading to the shape isomerism. The combined results of the present work and the previous $$alpha$$-decay and laser spectroscopy studies present evidence for triple shape coexistence at low energy in the negative-parity configurations of $$^{187}$$Pb, which is well reproduced by the potential-energy surface calculations.

論文

Effect of particle size on the colonization of biofilms and the potential of biofilm-covered microplastics as metal carriers

Wu, C.*; 田中 万也; 谷 幸則*; Bi, X.*; Liu, J.*; Yu, Q.*

Science of the Total Environment, 821, p.153265_1 - 153265_9, 2022/05

https://doi.org/10.1016/j.scitotenv.2022.153265
 被引用回数：48 パーセンタイル：96.66(Environmental Sciences)

異なる粒径のマイクロプラスチックを淡水性の真菌である${it Acremonium strictum}$ KR21-2株とともに培養し、マイクロプラスチック表面にバイオフィルムを形成させた。それらの物理化学的特性を調べた結果、バイオフィルムによる被覆により表面への重金属元素の吸着容量が高くなり、その程度はマイクロプラスチックの粒径に関係していることが明らかとなった。このことは、マイクロプラスチックがバイオフィルム形成を通じて環境中における重金属の重要なキャリアとなり得ることを示している。

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