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論文

In situ reaction and alteration of mudstone-cement interfaces at the Horonobe URL; Comparison between ordinary Portland cement and low alkaline cement

出井 俊太郎; 柴田 真仁*; 根岸 久美*; 杉浦 佑樹; 天野 由記; Bateman, K.*; Wilson, J.*; 横山 立憲; 鏡味 沙耶; 武田 匡樹; et al.

Results in Earth Sciences (Internet), 3, p.100097_1 - 100097_16, 2025/12

高レベル放射性廃棄物の地層処分において、セメントと泥岩の相互作用による化学的擾乱領域が形成され、岩盤中の核種移行特性に影響を及ぼす可能性がある。本研究では、11年前に幌延深地層研究センターの140m調査坑道に施工されたセメント(普通ポルトランドセメント(OPC)および低アルカリ性セメント(LAC))と泥岩の界面における変質状態について調査した。複数の分析手法を組み合わせることで、セメントの溶解、方解石やC-(A-)S-H相などの二次鉱物の析出、モンモリロナイトの陽イオン交換、泥岩の空隙率の低下など、セメントと岩石の界面における主要な反応が特定された。また、空隙率の低下による拡散の低下や、変質した泥岩中の二次鉱物への取り込みによる収着の促進など、セメントと泥岩の相互作用が放射性核種の移行に及ぼす影響についても明らかになった。

論文

Which radionuclides contribute most to seafood ingestion dose?

Johansen, M. P.*; Gwynn, J. P.*; Carpenter, J. G.*; Charmasson, S.*; 森 愛理; Orr, B.*; Simon-Cornu, M.*; Osvath, I.*; McGinnity, P.*

Journal of Environmental Radioactivity, 287, p.107706_1 - 107706_8, 2025/07

 被引用回数:0 パーセンタイル:0.00(Environmental Sciences)

Radiological ingestion doses from eating seafood are regularly evaluated near coastal nuclear facilities, following accidents/events and frequently in national studies worldwide. However, a recent global review found that published seafood doses varied greatly depending on which radionuclides were selected for evaluation and that there has been a tendency to omit important radionuclides or focus on less significant ones. This indicates a need for clear guidance on which radionuclides to prioritise in such studies. Here, we use worldwide data for 16 key radionuclides contributing to typical background seafood ingestion dose. We account for the loss of radionuclides during cooking and the radioactive decay of the short-lived $$^{210}$$Po. Results indicate that for the typical world consumer, naturally-occurring radionuclides account for $$>$$99% of the total seafood ingestion dose, of which about 84% comes from $$^{210}$$Po and 8% from $$^{210}$$Pb. About 5% comes from $$^{228}$$Ra, a far greater proportion than the more frequently-assessed $$^{226}$$Ra ($$<$$1%). Other Th- and U-series radionuclides provide far lower contributions (0.07%-0.70%), while $$^{14}$$C provides about 0.09%. In comparison, the contribution to total seafood ingestion dose from background anthropogenic radionuclides is $$<$$1%, with $$^{137}$$Cs contributing most (0.08%) and $$^{90}$$Sr, $$^{99}$$Tc, $$^{110m}$$Ag and $$^{239}$$Pu adding a further 0.05% together. These percentage contributions to dose can vary somewhat depending on consumption patterns (e.g., differing proportions of fish, bivalves, etc.). However, $$^{210}$$Po is the dominant contributor irrespective of country-specific diets or restricted diet scenarios (fish-only, seaweed-only, etc.). Study results provide new guidance to improve the design, interpretation and communication of seafood ingestion dose assessments.

論文

Temperature-dependent deformation behavior of dual-phase medium-entropy alloy; In-situ neutron diffraction study

Gu, G. H.*; Jeong, S. G.*; Heo, Y.-U.*; Harjo, S.; Gong, W.; Cho, J.*; Kim, H. S.*; 他4名*

Journal of Materials Science & Technology, 223, p.308 - 324, 2025/07

 被引用回数:0 パーセンタイル:0.00(Materials Science, Multidisciplinary)

Face-centered cubic (FCC) equi-atomic multi-principal element alloys (MPEAs) exhibit excellent mechanical properties from cryogenic to room temperatures. At room temperature, deformation is dominated by dislocation slip, while at cryogenic temperatures (CTs), reduced stacking fault energy enhances strain hardening with twinning. This study uses in-situ neutron diffraction to analyze the temperature-dependent deformation behavior of Al$$_{7}$$(CoNiV)$$_{93}$$, a dual-phase (FCC/BCC) medium-entropy alloy (MEA). At liquid nitrogen temperature (LNT), deformation twinning in the FCC matrix leads to additional strain hardening through the dynamic Hall-Petch effect, giving the appearance of improved strengthening at LNT. In contrast, BCC precipitates show dislocation slip at both 77 K and 298 K, with temperature-dependent lattice friction stress playing a significant role in strengthening. The study enhances understanding of deformation behaviors and provides insights for future alloy design.

論文

Complementary layer thickness effects of Q235 and SUS304 layers of multilayered steels for improving of tensile strength and plasticity simultaneously

Lin, Z. M.*; Liu, B. X.*; Ming, K. S.*; 徐 平光; Yin, F. X.*; Zheng, S. J.*

Scripta Materialia, 263, p.116692_1 - 116692_7, 2025/07

 被引用回数:0 パーセンタイル:0.00(Nanoscience & Nanotechnology)

Complementary layer thickness effects on strength and plasticity in Q235 and SUS304 steels provide a novel strategy to realize high strength and high plasticity of heterogeneous Q235/SUS304 multilayered steel. In this work, the tensile deformation behaviors and fracture characteristics of vacuum hot-rolled Q235/SUS304 multilayered steel with various layer thicknesses ranging from 223 $$mu$$m to 5 $$mu$$m were deeply investigated. The tensile strength improved with the reduction of layer thickness, and the uniform elongation were first increasing and then decreasing with the decrease of layer thickness, and the peak value appeared at the layer thickness of 20 $$mu$$m. Interestingly, the fracture elongation forms a high plateau value within the 10$$sim$$20 $$mu$$m range. Further analysis reveals that the severe strain localization in the brittle SUS304 thin layers is delayed by the ductile Q235 layers, which is mainly attributed to the different texture evolution and dislocation configuration characteristics during tensile deformation.

論文

Methods for regulating depth of corrosion fissures in simulated fastener holes of 7050-T7451 aluminum alloy

青山 高士; Choudhary, S.*; Pandaleon, A.*; Burns, J. T.*; Kokaly, M.*; Restis, J.*; Ross, J.*; Kelly, R. G.*

Corrosion, 81(6), p.609 - 621, 2025/06

This study presents a new test method for inducing controlled corrosion damage within simulated fastener holes of aluminum alloys, aimed at pretreating fatigue test specimens. The method involves insulating the outer surface while exposing the fastener hole surface to electrolytes containing 0.66 M NaCl + 0.1 M AlCl $$_{3}$$ with varying concentrations of K $$_{2}$$S $$_{2}$$O $$_{8}$$. The evolution of corrosion damage within the fastener hole was examined as a function of exposure duration, electrolyte composition, and volume, as well as the effect of galvanic coupling with a SS316 cathode. Results indicate that fissure depth increases with an increase in K $$_{2}$$S $$_{2}$$O $$_{8}$$ concentration but does not progress further after 24-48 hours of exposure in the chemical, or freely-corroding, exposure test. In contrast, galvanic coupling with a SS316 plate significantly accelerates corrosion, leading to much deeper fissures in a shorter time. The importance of electrolyte replenishment has been explored using electrochemical measurements, revealing the impact of evolving electrolyte chemistry. Beyond its application in fatigue specimen pretreatment, this method provides a simple yet effective approach for studying localized corrosion and evaluating mitigation strategies for fastener holes in aerospace structures.

論文

DECOVALEX-2023: An International collaboration for advancing the understanding and modeling of coupled thermo-hydro-mechanical-chemical (THMC) processes in geological systems

Birkholzer, J. T.*; Graupner, B. J.*; Harrington, J.*; Jayne, R.*; Kolditz, O.*; Kuhlman, K. L.*; LaForce, T.*; Leone, R. C.*; Mariner, P. E.*; McDermott, C.*; et al.

Geomechanics for Energy and the Environment, 42, p.100685_1 - 100685_17, 2025/06

 被引用回数:0

The DECOVALEX initiative is an international research collaboration (www.decovalex.org), initiated in 1992, for advancing the understanding and modeling of coupled thermo-hydro-mechanical-chemical (THMC) processes in geological systems. DECOVALEX stands for "DEvelopment of COupled Models and VALidation against EXperiments". DECOVALEX emphasizes joint analysis and comparative modeling of the complex perturbations and coupled processes in geologic repositories and how these impact long-term performance predictions. More than fifty research teams associated with 17 international DECOVALEX partner organizations participated in the comparative evaluation of eight modeling tasks covering a wide range of spatial and temporal scales, geological formations, and coupled processes. This Virtual Special Issue on DECOVALEX-2023 provides an in-depth overview of these collaborative research efforts and how these have advanced the state-of-the-art of understanding and modeling coupled THMC processes. While primarily focused on radioactive waste, much of the work included here has wider application to many geoengineering topics.

論文

Magnetism of kagome metals (Fe$$_{1-x}$$Co$$_x$$)Sn studied by $$mu$$SR

Cai, Y.*; Yoon, S.*; Sheng, Q.*; Zhao, G.*; Seewald, E. F.*; Ghosh, S.*; Ingham, J.*; Pasupathy, A. N.*; Queiroz, R.*; Lei, H.*; et al.

Physical Review B, 111(21), p.214412_1 - 214412_17, 2025/06

 被引用回数:0

We study the magnetic properties of the metallic kagome system (Fe$$_{1-x}$$Co$$_x$$)Sn by a combination of muon spin relaxation ($$mu$$SR), magnetic susceptibility, and scanning tunneling microscopy (STM) measurements in single crystal specimens with Co concentrations $$x$$ = 0, 0.11, 0.8. In the undoped antiferromagnetic compound FeSn, we find possible signatures for a previously unidentified phase that sets in at $$T^{*}sim 50$$~K, well beneath the Neel temperature $$T_{N}sim 376$$~K as indicated by a peak in the relaxation rate 1/$$T_1$$ observed in zero field (ZF) and longitudinal field (LF) $$mu$$SR measurements, with a corresponding anomaly in the ac and dc susceptibility, and an increase in the static width 1/$$T_2$$ in ZF-$$mu$$SR measurements. No signatures of spatial symmetry breaking are found in STM down to 7~K. Related to the location and motion of muons in FeSn, we confirmed a previous report that about 40% of the implanted muons reside at a field-cancelling high symmetry site at $$T < 250$$~K, while an onset of thermal hopping changes the site occupancy at higher temperatures. In Fe$$_{0.89}$$Co$$_{0.11}$$Sn, where disorder eliminated the field-cancellation effect, all the implanted muons exhibit precession and/or relaxation in the ordered state. In Fe$$_{0.2}$$Co$$_{0.8}$$Sn, we find canonical spin glass behavior with freezing temperature $$T_gsim 3.5$$~K; the ZF and LF-$$mu$$SR time spectra exhibit results similar to those observed in dilute alloy spin glasses CuMn and AuFe, with a critical behavior of $$1/T_1$$ at $$T_g$$ and $$1/T_1to 0$$ as $$Tto 0$$. The absence of spin dynamics at low temperatures makes a clear contrast to the spin dynamics observed by $$mu$$SR in many geometrically frustrated spin systems on insulating kagome, pyrochlore, and triangular lattices. The spin glass behavior of CoSn doped with dilute Fe moments is shown to originate primarily from the randomness of doped Fe moments rather than due to geometrical frustration of the underlying lattice.

論文

Impact of microdosimetric modeling on computation of relative biological effectiveness for carbon ion radiotherapy

Hartzell, S.*; Furutani, K. M.*; Parisi, A.*; 佐藤 達彦; 加瀬 優紀*; Deglow, C.*; Friedrich, T.*; Beltran, C. J.*

Radiation (Internet), 5(2), p.21_1 - 21_24, 2025/06

Microdosimetry is essential in particle therapy for understanding the biological effects of treatments by quantifying energy depositions within microscopic volumes. The calculation of the microdosimetric distributions can be carried out with physical models such as the Kiefer-Chatterjee (KC) track structure function and the Sato analytical microdosimetric function (AMF). Comprehensive comparisons across these physical models are lacking. The AMF is calculated for spherical domains, while the KC is traditionally calculated for a cylindrical domain. This study introduces a novel version of the KC function for spherical domains, allowing a direct comparison with AMF. The influence of each function on the calculation of the relative biological effectiveness (RBE) in carbon ion radiotherapy (CIRT) was evaluated.

論文

Nacre-like MXene/polyacrylic acid layer-by-layer multilayers as hydrogen gas barriers

Auh, Y. H.*; Neal, N. N.*; Arole, K.*; Regis, N. A.*; Nguyen, T.*; 小川 修一*; 津田 泰孝; 吉越 章隆; Radovic, M.*; Green, M. J.*; et al.

ACS Applied Materials & Interfaces, 17(21), p.31392 - 31402, 2025/05

 被引用回数:0 パーセンタイル:0.00(Nanoscience & Nanotechnology)

MXenes are a promising class of 2D nanomaterials and are of particular interest for gas barrier application. However, MXene nanosheets naturally bear a negative charge, which prevents assembly with negatively charged polymers, such as polyacrylic acid (PAA), into gas barrier coatings. Here, we present MXene- and PAA-based layer-by-layer (MXene/PAA LbL) multilayers formed by leveraging hydrogen bonding interactions. When assembled in acidic conditions, MXene/PAA LbL films exhibit conformal, pin-hole free, nacre-like structures. The MXene/PAA LbL films yield high blocking capability and low permeability (0.14$$pm$$0.01 cc mm m$$^{-2}$$ day$$^{-1}$$ MPa$$^{-1}$$) for hydrogen gas. These nacre-like structures are also electronically conductive (up to 370$$pm$$30 S cm$$^{-1}$$). Specifically, the reversible deconstruction of these films under basic conditions is experimentally verified. This study shows that hydrogen bonding interactions can be leveraged to form MXene LbL multilayers as gas barriers, electronically conducive coatings, and deconstructable thin films via pH control.

論文

A Review on the effect of iron on bentonite stability

Wilson, J.*; 笹本 広; 舘 幸男; 川間 大介*

Applied Clay Science, 275, p.107862_1 - 107862_15, 2025/05

 被引用回数:0

高レベル放射性廃棄物の処分場では、鉄または鋼製ベースの容器/オーバーパック及びベントナイト緩衝材が用いられる。25年以上にわたり、鉄とベントナイトの相互作用に関わる研究が行われ、その中では、特に膨潤性粘土(スメクタイト)の鉄に富んだ層状珪酸塩(膨潤能が欠落する鉱物も存在)への変質可能性について検討がなされた。このような変質が生じると、人工バリア材の一つである緩衝材に期待されている膨潤性の欠落或いは低下を引き起こし、せん断応力に対するオーバーパックの保護性、水や溶質の移行抑制にも影響を与える。鉄とベントナイトの相互作用に関わるデータの多くは、実験及び地球化学モデリングによるものであり、ナチュラルアナログによるデータには乏しい。これらの既往データによれば、スメクタイト(アルミ質のモンモリロナイト)が鉄に富んだ固相(層状珪酸塩を含む)に変質したものや、グリーンラスト又は磁鉄鉱のような腐食生成物を伴う鉄に富んだ変質ゾーンが生成される可能性が示唆される。一方、このような変質ゾーンについての実態は複雑であり、現状での理解は不十分な部分もある。25年以上にもわたり研究が行われているにもかかわらず不確実な部分も多いが、今回のレビューにより、鉄とベントナイトの相互作用に伴い生じる尤もらしいシナリオが認識され、考えられ得る緩衝材特性への影響についても提示された。

論文

Extending TOPAS with an analytical microdosimetric function; Application and benchmarking with nBio track structure simulations

Hartzell, S.*; Parisi, A.*; 佐藤 達彦; Beltran, C. J.*; Furutani, K. M.*

Physics in Medicine & Biology, 70(10), p.105010_1 - 105010_19, 2025/05

 被引用回数:0 パーセンタイル:0.00(Engineering, Biomedical)

In this study, we presented the implementation of the Analytical Microdosimetric Function (AMF) within the TOPAS Monte Carlo platform as an efficient and accurate surrogate for track structure simulations. The AMF extension demonstrated strong agreement with TOPAS nBio track structure simulations for ions relevant to particle therapy and space applications, while offering significant computational advantages.

論文

Electrocatalytic nitrous oxide reduction reaction at Sn-modified Pd-Pt single crystalline electrodes in acidic media

加藤 優*; Zheng, J.*; Deng, Y.*; 斎藤 史恵*; 鵜沼 佑規*; 岡 紗雪*; 田村 和久; 八木 一三*

ACS Catalysis, 15(10), p.7710 - 7719, 2025/04

 被引用回数:0 パーセンタイル:0.00(Chemistry, Physical)

Nitrous oxide (N$$_{2}$$O) is a greenhouse and an ozone-depleting gas. Electrocatalytic N$$_{2}$$O reduction reaction (N$$_{2}$$ORR) is known to be catalyzed at noble metal electrodes such as Pd and Pt, and the surface modification of such noble metals with Sn is known to increase the N$$_{2}$$ORR in acidic media. However, the role of Sn at the surface remains unclear. In this work, N$$_{2}$$ORR activity was investigated for single-crystalline Pt, Pd, and Pd-Pt electrodes with the (111) or (100) plane in the presence and absence of Sn at the electrode surface in acidic media. In situ X-ray crystal truncation rod (CTR) measurements of Sn-modified Pt(111) and Pd(111) electrodes revealed the presence of metallic Sn and SnO at their surfaces. The surface Sn modification enhances the N$$_{2}$$ORR activity for Pd-Pt(100) or Pd(100) electrodes but not for the Pt(111), Pd-Pt(111), or Pt(100) electrodes.

論文

Synthesis of BaSiH$$_6$$ hydridosilicate at high pressures; A Bridge to BaSiH$$_8$$ polyhydride

Beyer, D. C.*; Spektor, K.*; Vekilova, O. Y.*; Grins, J.*; Barros Brant Carvalho, P. H.*; Leinbach, L. J.*; Sannemo-Targama, M.*; Bhat, S.*; Baran, V.*; Etter, M.*; et al.

ACS Omega (Internet), 10(15), p.15029 - 15035, 2025/04

 被引用回数:0 パーセンタイル:0.00(Chemistry, Multidisciplinary)

SiH$$_6$$八面体部位を特徴とするヒドリドケイ酸塩は、水素貯蔵と水素化物イオン伝導に関連する潜在的な性質を持つかなり新しい化合物のクラスである。ここでは、Zintl相水素化物BaSiH$$_{sim 1.8}$$を4GPa以上の圧力でH$$_2$$流体と反応させ、その後常圧まで減圧して得られた新しい代表的なBaSiH$$_6$$について報告する。SiH$$_{6}^{2-}$$イオンはBa$$^{2+}$$対イオンによって八面体に配位している。Ba原子とSi原子の配置は理想的なfcc NaCl構造からわずかにずれている。IRとラマンスペクトルからSiH$$_{6}^{2-}$$の屈曲と伸縮モードがそれぞれ800-1200と1400-1800cm$$^{-1}$$の範囲で観測された。BaSiH$$_6$$は95$$^circ$$Cまで熱的に安定であり、それ以上ではBaH$$_2$$とSiに分解する。DFT計算により、直接バンドギャップは2.5eVであることが示された。BaSiH$$_6$$の発見により、ギガパスカル圧力(10GPa以下)のシリサイドの水素化反応からアクセス可能なヒドリドケイ酸塩の化合物クラスが固まった。BaSiH$$_6$$の構造的性質は、超伝導ポリハイドライドBaSiH$$_8$$を予測されるより高い圧力で水素化するための中間体(あるいは前駆体)であることを示唆している。

論文

Residual stress measurement and lifetime evaluation of railway axles by neutron scattering technology

Hu, F.-F.*; Qin, T.-Y.*; Ao, N.*; 徐 平光; Su, Y. H.; Parker, J. D.*; 篠原 武尚; 菖蒲 敬久; Kang, G.-Z.*; Ren, M.-M.; et al.

Journal of Traffic and Transportation Engineering, 25(2), p.75 - 93, 2025/04

To accurately predict the remaining lifetime of surface-strengthened railway axles, a damage tolerance method considering three-dimensional (3D) residual stresses was proposed. By taking the induction-hardened carbon steel S38C axle as an example, two-dimensional (2D) distribution characterization of residual strain and 3D residual stress measurement were performed through comprehensive application of the neutron Bragg-edge transmission imaging and angle-dispersive neutron diffraction experiments. A numerical method was employed to implant the 3D residual stress into the axle model, and the remaining lifetime of the full-scale axle was studied by coupling the measured load spectrum, press-fit loads, and residual stresses. Experimental results shows that, both axial and hoop directions present a compressive residual strain gradient layer of about 3 mm, with a maximum compressive residual strain of up to -4500 $$mu$$$$varepsilon$$ in the surface layer, yet a maximum tensile strain of up to 1000 $$mu$$$$varepsilon$$ in the core. The maximum axial and hoop compressive stresses of the axle are about -500 MPa and -303 MPa respectively, while radial stresses overall fluctuate in the zero mean stress range. At depths beyond 4.5 mm from the surface layer, all three components are tensile stresses. The axle surface layer is subjected to compressive residual stresses, and crack propagation does not occur if the crack depth is less than 4.5 mm. Nevertheless, cracks propagate accelerates when the crack depth is greater than 4.5 mm. Different crack propagation depth thresholds lead to a larger calculated remaining lifetime for the residual stress-free condition than for the case where 3D residual stresses are taken into account. However, the axle remaining service mileage of the axle of 227000 Km under the most conservative conditions exceeds 3.5 non-destructive inspection (NDI) cycles, with a large safety margin. The experimental results can provide a scientific reference for the development and optimization of NDI cycles for surface-strengthened railway axles.

論文

Ordered graphane nanoribbons synthesized via high-pressure diels-alder polymerization of 2,2'-bipyrazine

Li, F.*; Tang, X.*; Fei, Y.*; Zhang, J.*; Liu, J.*; Lang, P.*; Che, G.*; Zhao, Z.*; Zheng, Y.*; Fang, Y.*; et al.

Journal of the American Chemical Society, 147(17), p.14054 - 14059, 2025/04

 被引用回数:1 パーセンタイル:0.00(Chemistry, Multidisciplinary)

2,2'-ビピラジン(BPZ)の圧力誘起重合により結晶性グラファンナノリボン(GANR)を合成した。中性子回折データのリートベルト精密化,核磁気共鳴スペクトル,赤外スペクトル,理論計算を行った結果、BPZは$$pi$$ $$cdots$$ $$pi$$積層した芳香環の間でディールス・アルダー重合し、並外れた長距離秩序を持つ伸びたボート型GANR構造を形成することがわかった。未反応の-C=N-基がボートの両端を橋渡ししており、さらなる機能化の余地がある。このGANRのバンドギャップは2.25eVであり、光電応答は良好である(I$$_{on}$$/I$$_{off}$$ =18.8)。われわれの研究は、高圧トポケミカル重合法が、特定の構造と望んだ特性を持つグラファンの精密な合成に有望な方法であることを強調している。

論文

Neutron spectroscopy study on crystalline electric field excitations in NdB$$_4$$

山内 宏樹; 目時 直人; 綿貫 竜太*; Hong, T.*; Fernandez-Baca, J. A.*; 萩原 雅人; 益田 隆嗣*; 吉沢 英樹*; 伊藤 晋一*

Journal of the Physical Society of Japan, 94(5), p.054705_1 - 054705_8, 2025/04

The $textit{f}$-electron states of NdB$$_4$$ were determined by observing crystalline electric field (CEF) excitations with inelastic neutron scattering experiments. Our analysis yields CEF excitation energies of 2.8, 12.4, 17.2, and 25.4 meV. The $textit{f}$-electron states are simply described by one of $$J$$-multiplets $$left|pm J_z rightrangle$$ with negligibly small mixing. The ground state is the pseudo-quartet consist of the ground doublet dominated by $$left|pm frac{5}{2} rightrangle$$ and the first excited doublet dominated by $$left|pm frac{7}{2} rightrangle$$ at 2.8 meV, which is consistent with magnetic specific heat and entropy reported in earlier study. The simple $textit{f}$-electron states in NdB$$_4$$ are the consequence of the strong uniaxial and in-plane isotropic CEF potential due to the local structure of Nd$$^{3+}$$ ions with point symmetry $$C_{2v}$$.

論文

Competition between mass-symmetric and asymmetric fission modes in $$^{258}$$Md produced in the $$^{4}$$He + $$^{254}$$Es reaction

西尾 勝久; 廣瀬 健太郎; 牧井 宏之; Orlandi, R.; Kean, K. R.*; 塚田 和明; 豊嶋 厚史*; 浅井 雅人; 佐藤 哲也; Chiera, N. M.*; et al.

Physical Review C, 111(4), p.044609_1 - 044609_12, 2025/04

 被引用回数:0 パーセンタイル:0.00(Physics, Nuclear)

In spontaneous fission (SF) it is found that the mass-asymmetric fission of well-known actinides suddenly changes to the symmetric fission when nucleus has a mass number $$A_{c}$$ larger than 257. We have measured for the first time fission-fragment mass and total-kinetic-energy (TKE) distributions of the excited compound nucleus $$^{258}$$Md, populated in the reaction $$^{4}$$He+$$^{254}$$Es, using the rare isotope $$^{254}$$Es with a short half-life, $$T_{1/2}$$=276 days. The fission of $$^{258}$$Md can be interpreted as involving 3 fission modes: an mass-asymmetric mode and two modes of mass-asymmetric fissions, the latter two are manifested by different TKE values. Predominantly symmetric fission was obtained at the excitation energy of 15.0 MeV. By increasing the energy to 18.0 MeV, the asymmetric fission mode dominates. Both such a strong change of fission modes within a small increase of excitation energy and the enhancement of asymmetric split are new phenomena in fission.

論文

Electronic approach to understand the wettability of surface treated titanium with liquid sodium

浪江 将成; 斉藤 淳一; 岡 涼太郎*; Kim, J.-H.*

Vacuum, 234, p.114038_1 - 114038_9, 2025/04

 被引用回数:0 パーセンタイル:0.00(Materials Science, Multidisciplinary)

Wettability of titanium (Ti) and surface-modified (Oxidized or Fluorinated) Ti with liquid sodium (Na) were investigated via experiments and theoretical calculations. From the experimental results, a sliding angle of Na droplet on oxidized Ti was smaller than that on untreated Ti, indicating the worsening of wettability by oxidation. In contrast, the sliding angle of Na droplet on fluoridated Ti was larger than that on untreated Ti, indicating an improvement in wettability by fluorination. Additionally, the cluster models for the interface between Na droplets and treated or untreated Ti were constructed for theoretical calculations of electronic states at the interface, covalent and ionic bonds at the interface were evaluated from the calculation results. The sliding angles obtained in the wettability tests and the strength of covalent bonding at the interface showed no correlation, but good correlation was observed between the sliding angles and ionic bonding at the interface. Thus, the wettability of surface-modified Ti with liquid Na can be theoretically understood based on the atomic interactions at the interface.

論文

Magnetite stoichiometry (Fe(II)/Fe(III)) controls on trivalent chromium surface speciation

Scaria, J.*; P$'e$drot, M.*; Fablet, L.*; 蓬田 匠; Nguyen, T. T.*; Sivry, Y.*; Catrouillet, C.*; Pradas del Real, A. E.*; Choueikani, F.*; Vantelon, D.*; et al.

Environmental Science & Technology, 59(11), p.5747 - 5755, 2025/03

 被引用回数:1 パーセンタイル:0.00(Engineering, Environmental)

クロム(Cr)とマグネタイトの相互作用メカニズムを理解し予測することは、環境中のCrの物地球化学的挙動を解明し、最適な土壌浄化および水処理戦略を開発する上で特に重要である。最も毒性の高いCr(VI)がCr(III)に還元されて除去されることは広く報告されているが、Cr(III)のマグネタイトへの吸着に関わる正確なメカニズムは解明されていなかった。本研究では、Cr(III)溶液と10nmサイズのマグネタイトの相互作用を調べた。本研究では、pHとマグネタイトの化学量論の双方がCr(III)吸着メカニズムに及ぼす複合的な影響を調べることで、Cr(III)-(hydr)Oxide沈殿の生成が必ずしも溶液からのCr(III)の除去を駆動するプロセスではないことが明らかになった。これらの結果は、環境中のCrの輸送と終着点の予測、およびマグネタイトを用いたCr浄化プロセスの開発に役立つと期待される。

論文

Comparative analysis of primary variables selection in modeling non-isothermal two-phase flow; Insights from EBS experiment at Horonobe URL

Kim, M.*; Lee, C.*; 杉田 裕; Kim, J.-S.*; Jeon, M.-K.*

Geomechanics for Energy and the Environment, 41, p.100628_1 - 100628_9, 2025/03

 被引用回数:1 パーセンタイル:0.00(Energy & Fuels)

この研究では、DECOVALEX-2023プロジェクトの一環として幌延の地下研究施設で実施された実規模大の人工バリア試験の数値解析を使用して、非等温二相流のモデリングに対する主要変数の選択の影響を調査した。検証済みの数値モデルを使用して、人工バリアシステム内の不均質多孔質媒体の熱-水連成挙動を解析した。支配方程式を離散化する際の2つの異なる主要変数スキームを比較したところ、結果に大きな違いがあることが明らかになった。

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