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Journal Articles

Development of a non-destructive depth-selective quantification method for sub-percent carbon contents in steel using negative muon lifetime analysis

Ninomiya, Kazuhiko*; Kubo, Kenya*; Inagaki, Makoto*; Yoshida, Go*; Chiu, I.-H. ; Kudo, Takuto*; Asari, Shunsuke*; Sentoku, Sawako*; Takeshita, Soshi*; Shimomura, Koichiro*; et al.

Scientific Reports (Internet), 14, p.1797_1 - 1797_8, 2024/01

The amount of C in steel, which is critical in determining its properties, is strongly influenced by steel production technology. We propose a novel method of quantifying the bulk C content in steel non-destructively using muons. This revolutionary method may be used not only in the quality control of steel in production, but also in analyzing precious steel archaeological artifacts. A negatively charged muon forms an atomic system owing to its negative charge, and is finally absorbed into the nucleus or decays to an electron. The lifetimes of muons differ significantly, depending on whether they are trapped by Fe or C atoms, and identifying the elemental content at the muon stoppage position is possible via muon lifetime measurements. The relationship between the muon capture probabilities of C/Fe and the elemental content of C exhibits a good linearity, and the C content in the steel may be quantitatively determined via muon lifetime measurements. Furthermore, by controlling the incident energies of the muons, they may be stopped in each layer of a stacked sample consisting of three types of steel plates with thicknesses of 0.5 mm, and we successfully determined the C contents in the range 0.20 - 1.03 wt% depth-selectively, without sample destruction.

Journal Articles

Machine learning molecular dynamics reveals the structural origin of the first sharp diffraction peak in high-density silica glasses

Kobayashi, Keita; Okumura, Masahiko; Nakamura, Hiroki; Itakura, Mitsuhiro; Machida, Masahiko; Urata, Shingo*; Suzuya, Kentaro

Scientific Reports (Internet), 13, p.18721_1 - 18721_12, 2023/11

The first sharp peak diffraction peak (FSDP) in the structure factor of amorphous materials is thought to reflect the medium-range order structure in amorphous materials, and the structural origin of the FSDP has been a subject of ongoing debate. In this study, we employed machine learning molecular dynamics (MLMD) with nearly first-principles calculation accuracy to investigate the structural origin of the FSDP in high-density silica glass. First, we successfully reproduced various experimental data of high-density silica glass using MLMD. Furthermore, we revealed that the development (or reduction) of the FSDP in high-density silica glass is characterized by the deformation behavior of ring structures in Si-O covalent bond networks under compression.

Journal Articles

Exploring spin-polarization in Bi-based high-$$T_c$$ cuprates

Iwasawa, Hideaki*; Sumida, Kazuki; Ishida, Shigeyuki*; Le F$`e$vre, P.*; Bertran, F.*; Yoshida, Yoshiyuki*; Eisaki, Hiroshi*; Santander-Syro, A.*; Okuda, Taichi*

Scientific Reports (Internet), 13, p.13451_1 - 13451_7, 2023/08

Journal Articles

Atomic reconstruction induced by uniaxial stress in MnP

Kozawa, Tatsuya*; Fujihara, Masayoshi; Uchihara, Takeru*; Mitsuda, Setsuo*; Yano, Shinichiro*; Tamatsukuri, Hiromu; Munakata, Koji*; Nakao, Akiko*

Scientific Reports (Internet), 13, p.13750_1 - 13750_8, 2023/08

In condensed matter physics, pressure is frequently used to modify the stability of both electronic states and atomic arrangements. Under isotropic pressure, the intermetallic compound MnP has recently attracted attention for the interplay between pressure-induced superconductivity and complicated magnetic order in the vicinity. By contrast, we use uniaxial stress, a directional type of pressure, to investigate the effect on the magnetism and crystal structure of this compound. An irreversible magnetisation response induced by uniaxial stress is discovered in MnP at uniaxial stress as low as 0.04 GPa. Neutron diffraction experiments reveal that uniaxial stress forms crystal domains that satisfy pseudo-rotational symmetry unique to the MnP-type structure. The structure of the coexisting domains accounts for the stress-induced magnetism. We term this first discovered phenomenon atomic reconstruction (AR) induced by uniaxial stress. Furthermore, our calculation results provide guidelines on the search for AR candidates. AR allows crystal domain engineering to control anisotropic properties of materials, including dielectricity, elasticity, electrical conduction, magnetism and superconductivity. A wide-ranging exploration of potential AR candidates would ensure that crystal domain engineering yields unconventional methods to design functional multi-domain materials for a wide variety of purposes.

Journal Articles

Neutron resonance absorption imaging of simulated high-level radioactive waste in borosilicate glass

Oba, Yojiro; Motokawa, Ryuhei; Kaneko, Koji; Nagai, Takayuki; Tsuchikawa, Yusuke; Shinohara, Takenao; Parker, J. D.*; Okamoto, Yoshihiro

Scientific Reports (Internet), 13, p.10071_1 - 10071_8, 2023/06

 Times Cited Count:0 Percentile:0.01

Journal Articles

Ultrafast electron dynamics in a topological surface state observed in two-dimensional momentum space

Reimann, J.*; Sumida, Kazuki; Kakoki, Masaaki*; Kokh, K. A.*; Tereshchenko, O. E.*; Kimura, Akio*; G$"u$dde, J.*; H$"o$fer, U.*

Scientific Reports (Internet), 13, p.5796_1 - 5796_8, 2023/04

 Times Cited Count:0 Percentile:0(Multidisciplinary Sciences)

Journal Articles

Analysis of gadolinium oxide using microwave-enhanced fiber-coupled micro-laser-induced breakdown spectroscopy

Ikeda, Yuji*; Soriano, J. K.*; Oba, Hironori; Wakaida, Ikuo

Scientific Reports (Internet), 13, p.4828_1 - 4828_9, 2023/03

 Times Cited Count:0 Percentile:97.97(Multidisciplinary Sciences)

Journal Articles

Breaking the hard-sphere model with fluorite and antifluorite solid solutions

Vauchy, R.; Hirooka, Shun; Watanabe, Masashi; Kato, Masato

Scientific Reports (Internet), 13, p.2217_1 - 2217_8, 2023/02

 Times Cited Count:1 Percentile:94.96(Multidisciplinary Sciences)

Journal Articles

Dependence of column ozone on future ODSs and GHGs in the variability of 500-ensemble members

Akiyoshi, Hideharu*; Kadowaki, Masanao; Yamashita, Yosuke*; Nagatomo, Toshiharu*

Scientific Reports (Internet), 13, p.320_1 - 320_12, 2023/01

 Times Cited Count:0 Percentile:67.22

State-of-the-art chemistry climate models (CCMs) have indicated that a future decrease in ozone-depleting substances (ODSs) combined with an increase in greenhouse gases (GHGs) would increase the column ozone amount in most regions except the tropics and Antarctic. However, large Arctic ozone losses have occurred at a frequency of approximately once per decade since the 1990s, despite the ODS concentration peaking in the mid-1990s. To understand this, CCMs were used to conduct 24 experiments with ODS and GHG concentrations set based on predicted values for future years; each experiment consisted of 500-member ensembles. The 50 ensemble members with the lowest column ozone in the mid- and high latitudes of the Northern Hemisphere showed a clear ODS dependence associated with low temperatures and a strong westerly zonal mean zonal wind. Even with high GHG concentrations, several ensemble members showed extremely low spring column ozone in the Arctic when ODS concentration remained above the 1980-1985 level. Hence, ODS concentrations should be reduced to avoid large ozone losses in the presence of a stable Arctic polar vortex. The average of the lowest 50 members indicates that GHG increase towards the end of the twenty-first century will not cause worse Arctic ozone depletion.

Journal Articles

Magnon mode transition in real space

Iida, Kazuki*; Kodama, Katsuaki; Inamura, Yasuhiro; Nakamura, Mitsutaka; Chang, L.-J.*; Shamoto, Shinichi

Scientific Reports (Internet), 12, p.20663_1 - 20663_7, 2022/12

 Times Cited Count:0 Percentile:0(Multidisciplinary Sciences)

Spin excitation of an ilmenite FeTiO$$_{3}$$ powder sample is measured by time-of-flight inelastic neutron scattering. The dynamic magnetic pair-density function $$D_{M}(r,E)$$ is obtained from the dynamic magnetic structure factor $$S_{M}(Q,E)$$ by the Fourier transformation.

Journal Articles

Crystallinity in periodic nanostructure surface on Si substrates induced by near- and mid-infrared femtosecond laser irradiation

Miyagawa, Reina*; Kamibayashi, Daisuke*; Nakamura, Hirotaka*; Hashida, Masaki*; Zen, H.*; Somekawa, Toshihiro*; Matsuoka, Takeshi*; Ogura, Hiroyuki*; Sagae, Daisuke*; Seto, Yusuke*; et al.

Scientific Reports (Internet), 12, p.20955_1 - 20955_8, 2022/12

 Times Cited Count:0 Percentile:0(Multidisciplinary Sciences)

We evaluated Laser-Induced Periodic Surface Structure (LIPSS) crystal structures using the stress imaging station at BL22XU of JAEA-BL on SPring-8. Crystallization of LIPPS was used different two types laser these are Ti:Sapphire laser (wavelength: 800 nm) and MIR-FEL (mid-infrared free electron laser, wavelength 11.4 $$mu$$m). These lasers are different in the laser pulse structure and the wavelength. We investigated on the effects of formed LIPSS crystallization using different kind of laser. Measured synchrotron X-ray energy is 30 keV and beam size is 20 $$mu$$m. Detector of diffracted X-ray is two-dimensional detector (PILATUS300K, DECTRIS). LIPSS formed using Ti:Sapphire laser has deformed structure with good crystallinity. LIPSS formed using MIR-FEL has dislocation or fault without structural stress. These results show depending on select of laser forming LIPPS structure. These information becomes important a point of the functional application of LIPSS.

Journal Articles

Cleavages along {110} in bcc iron emit dislocations from the curved crack fronts

Suzudo, Tomoaki; Ebihara, Kenichi; Tsuru, Tomohito; Mori, Hideki*

Scientific Reports (Internet), 12, p.19701_1 - 19701_10, 2022/11

 Times Cited Count:0 Percentile:47.64(Multidisciplinary Sciences)

Body-centered-cubic (bcc) transition metals, such as $$alpha$$-Fe and W, cleave along the {100} plane, even though the surface energy is the lowest along the {110} plane. To unravel the mechanism of this odd response, large-scale atomistic simulations of curved cleavage cracks of $$alpha$$-Fe were conducted in association with stress intensity factor analyses of straight crack fronts using an interatomic potential created by an artificial neural network technique. The study provides novel findings: Dislocations are emitted from the crack fronts along the {110} cleavage plane, and this phenomenon explains why the {100} plane can be the cleavage plane. However, the simple straight crack-front analyses did not yield the same conclusion. It is suggested that atomistic modeling, at sufficiently large scales to capture the inherent complexities of materials using highly accurate potentials, is necessary to correctly predict the mechanical strength. The method adopted in this study is generally applicable to the cleavage problem of bcc transition metals and alloys.

Journal Articles

Impact of the Lorentz force on electron track structure and early DNA damage yields in magnetic resonance-guided radiotherapy

Yachi, Yoshie*; Kai, Takeshi; Matsuya, Yusuke; Hirata, Yuho; Yoshii, Yuji*; Date, Hiroyuki*

Scientific Reports (Internet), 12, p.16412_1 - 16412_8, 2022/09

 Times Cited Count:3 Percentile:52.59(Multidisciplinary Sciences)

Recently, magnetic resonance-guided radiotherapy (MRgRT) which can visualize tumors in real time has been developed and installed in several clinical facilities. It is known that Lorentz force modulate macroscopic dose distribution by a charged particle, however, the impact by the force on microscopic radiation-track structure and early DNA damage induction remain unclear. In this study, we simulated the electron-track structure in a static magnetic field using a PHITS, and estimated features of biological effects. We indicated that the macroscopic dose distributions are changed by the force, while early DNA damage such as double strand breaks is attributed to the secondary electrons below a few tens of eV which are independent of the force. We expect that our insight significantly contributes to the MRgRT.

Journal Articles

Atomistic weak interaction criterion for the specificity of liquid metal embrittlement

Yamaguchi, Masatake; Tsuru, Tomohito; Itakura, Mitsuhiro; Abe, Eiji*

Scientific Reports (Internet), 12(1), p.10886_1 - 10886_7, 2022/07

 Times Cited Count:0 Percentile:0(Multidisciplinary Sciences)

no abstracts in English

Journal Articles

Machine learning molecular dynamics simulations toward exploration of high-temperature properties of nuclear fuel materials; Case study of thorium dioxide

Kobayashi, Keita; Okumura, Masahiko; Nakamura, Hiroki; Itakura, Mitsuhiro; Machida, Masahiko; Cooper, M. W. D.*

Scientific Reports (Internet), 12(1), p.9808_1 - 9808_11, 2022/06

 Times Cited Count:1 Percentile:71.95(Multidisciplinary Sciences)

no abstracts in English

Journal Articles

Effect of sample density in prompt $$gamma$$-ray analysis

Maeda, Makoto; Segawa, Mariko; Toh, Yosuke; Endo, Shunsuke; Nakamura, Shoji; Kimura, Atsushi

Scientific Reports (Internet), 12(1), p.6287_1 - 6287_8, 2022/06

 Times Cited Count:2 Percentile:37.28(Multidisciplinary Sciences)

Journal Articles

Analysis of particles containing alpha-emitters in stagnant water at torus room of Fukushima Dai-ichi Nuclear Power Station's Unit 2 reactor

Yomogida, Takumi; Ouchi, Kazuki; Oka, Toshitaka; Kitatsuji, Yoshihiro; Koma, Yoshikazu; Konno, Katsuhiro*

Scientific Reports (Internet), 12(1), p.7191_1 - 7191_10, 2022/05

 Times Cited Count:3 Percentile:60.07(Multidisciplinary Sciences)

Particles containing alpha ($$alpha$$) nuclides were identified from sediment in stagnant water at the torus room of the Fukushima Dai-ichi Nuclear Power Station (FDiNPS)'s Unit 2 reactor. Several uranium-bearing particles were identified by SEM observation. These particles contained Zr and other elements which constituted fuel cladding and structural materials. The $$^{235}$$U/$$^{238}$$U isotope ratio in the solid fractions that included U particles was consistent with the nuclear fuel in the Unit 2 reactor, which indicated that the U particles had been derived from nuclear fuel. The particles with alpha-emitters detected by alpha track analysis were several tens to several hundred $$mu$$m in size. The EDX spectra showed that these particles mainly comprised iron, which indicated Pu, Am, and Cm were adsorbed on the Fe-baring particles. This study clarifies that the major morphologies of U and other $$alpha$$-nuclides were differed in the sediment of stagnant water in the torus room of FDiNPS's Unit 2 reactor.

Journal Articles

In-situ neutron diffraction study of lattice deformation behaviour of commercially pure titanium at cryogenic temperature

Lee, M.-S.*; Kawasaki, Takuro; Yamashita, Takayuki*; Harjo, S.; Hyun, Y.-T.*; Jeong, Y.*; Jun, T.-S.*

Scientific Reports (Internet), 12(1), p.3719_1 - 3719_10, 2022/03

 Times Cited Count:2 Percentile:65.83(Multidisciplinary Sciences)

Journal Articles

Radiochemical analysis of the drain water sampled at the exhaust stack shared by Units 1 and 2 of the Fukushima Daiichi Nuclear Power Station

Shimada, Asako; Taniguchi, Yoshinori; Kakiuchi, Kazuo; Ohira, Saki; Iida, Yoshihisa; Sugiyama, Tomoyuki; Amaya, Masaki; Maruyama, Yu

Scientific Reports (Internet), 12(1), p.2086_1 - 2086_11, 2022/02

 Times Cited Count:0 Percentile:35.78(Multidisciplinary Sciences)

no abstracts in English

Journal Articles

Tumor radioresistance caused by radiation-induced changes of stem-like cell content and sub-lethal damage repair capability

Fukui, Roman*; Saga, Ryo*; Matsuya, Yusuke; Tomita, Kazuo*; Kuwahara, Yoshikazu*; Ouchi, Kentaro*; Sato, Tomoaki*; Okumura, Kazuhiko*; Date, Hiroyuki*; Fukumoto, Manabu*; et al.

Scientific Reports (Internet), 12(1), p.1056_1 - 1056_12, 2022/01

 Times Cited Count:6 Percentile:89.56(Multidisciplinary Sciences)

Alive cancer cells after fractionated irradiations with 2 Gy X-rays per day for more than 30 days show clinically relevant radioresistant. Such radioresistance is experimentally interpreted to attributed to the increment of stem-like cell content. However, only an experimental approach cannot clarify the cell responses (DNA damage and cell death induction) of cancer stem cells, so the radioresistant mechanisms remain uncertain. In addition to the conventional cell experiments using radio-resistant cell lines established after fractionated irradiations, in this study we developed a mathematical model (so called integrated microdosimetric-kinetic (IMK) model) explicitly considering cancer stem-like cell content and DNA damage responses and investigated radioresistant mechanisms acquired after fractionated irradiations. The IMK model analysis suggested that the changes of stem-like cell fraction and DNA repair efficiency play important roles of radioresisitance acquired after irradiations. Considering these into the IMK model, we successfully reproduced the experimental survival of various cell lines and various irradiation conditions. This work would contribute to not only the precise understanding of the radioresistant mechanisms induced after irradiation but also predicting curative effects with high precision.

126 (Records 1-20 displayed on this page)