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Journal Articles

Neutron spin-echo studies of the structural relaxation of network liquid ZnCl$$_2$$ at the structure factor primary peak and prepeak

Luo, P.*; Zhai, Y.*; Leao, J. B.*; Kofu, Maiko; Nakajima, Kenji; Faraone, A.*; Zhang, Y.*

Journal of Physical Chemistry Letters (Internet), 12(1), p.392 - 398, 2021/01

 Times Cited Count:1 Percentile:70.6(Chemistry, Physical)

Using neutron spin-echo spectroscopy, we studied the microscopic structural relaxation of a prototypical network ionic liquid ZnCl$$_2$$ at the structure factor primary peak and prepeak. The results show that the relaxation at the primary peak is faster than the prepeak and that the activation energy is $$sim 33$$% higher. A stretched exponential relaxation is observed even at temperatures well-above the melting point $$T_{rm m}$$. Surprisingly, the stretching exponent shows a rapid increase upon cooling, especially at the primary peak, where it changes from a stretched exponential to a simple exponential on approaching the $$T_{rm m}$$. These results suggest that the appearance of glassy dynamics typical of the supercooled state even in the equilibrium liquid state of ZnCl$$_2$$ as well as the difference of activation energy at the two investigated length scales are related to the formation of a network structure on cooling.

Journal Articles

DMFT reveals the non-Hermitian topology and Fermi arcs in heavy-fermion systems

Nagai, Yuki; Qi, Y.*; Isobe, Hiroki*; Kozii, V.*; Fu, L.*

Physical Review Letters, 125(22), p.227204_1 - 227204_7, 2020/11

 Times Cited Count:7 Percentile:77.76(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Distance-selected topochemical dehydro-diels-alder reaction of 1,4-Diphenylbutadiyne toward crystalline graphitic nanoribbons

Zhang, P.*; Tang, X.*; Wang, Y.*; Wang, X.*; Gao, D.*; Li, Y.*; Zheng, H.*; Wang, Y.*; Wang, X.*; Fu, R.*; et al.

Journal of the American Chemical Society, 142(41), p.17662 - 17669, 2020/10

 Times Cited Count:6 Percentile:75.63(Chemistry, Multidisciplinary)

Solid-state topochemical polymerization (SSTP) is a promising method to construct functional crystalline polymeric materials, but in contrast to various reactions that happen in solution, only very limited types of SSTP reactions are reported. Diels-Alder (DA) and dehydro-DA (DDA) reactions are textbook reactions for preparing six-membered rings in solution but are scarcely seen in solid-state synthesis. Here, using multiple cutting-edge techniques, we demonstrate that the solid 1,4-diphenylbutadiyne (DPB) undergoes a DDA reaction under 10-20 GPa with the phenyl as the dienophile. The crystal structure at the critical pressure shows that this reaction is "distance-selected". The distance of 3.2${AA}$ between the phenyl and the phenylethynyl facilitates the DDA reaction, while the distances for other DDA and 1,4-addition reactions are too large to allow the bonding. The obtained products are crystalline armchair graphitic nanoribbons, and hence our studies open a new route to construct the crystalline carbon materials with atomic-scale control.

Journal Articles

Ultralow thermal conductivity from transverse acoustic phonon suppression in distorted crystalline $$alpha$$-MgAgSb

Li, X.*; Liu, P.-F.*; Zhao, E.*; Zhang, Z.*; Guide, T.*; Le, M. D.*; Avdeev, M.*; Ikeda, Kazutaka*; Otomo, Toshiya*; Kofu, Maiko; et al.

Nature Communications (Internet), 11(1), p.942_1 - 942_9, 2020/02

 Times Cited Count:15 Percentile:93.25(Multidisciplinary Sciences)

In high-performance thermoelectric materials, there are two main low thermal conductivity mechanisms: the phonon anharmonic and phonon scattering resulting from the dynamic disorder, which have been successfully revealed by inelastic neutron scattering. Using neutron scattering and ab initio calculations, we report here a mechanism of static local structure distortion combined with phonon-anharmonic-induced ultralow lattice thermal conductivity in $$alpha$$-MgAgSb. Since the transverse acoustic phonons are almost fully scattered by the intrinsic distorted rocksalt sublattice in this compound, the heat is mainly transported by the longitudinal acoustic phonons. The ultralow thermal conductivity in $$alpha$$-MgAgSb is attributed to its atomic dynamics being altered by the structure distortion, which presents a possible microscopic route to enhance the performance of similar thermoelectric materials.

Journal Articles

Investigation of the electronic structure and lattice dynamics of the thermoelectric material Na-doped SnSe

Wu, P.*; Zhang, B.*; Peng, K. L.*; Hagiwara, Masayuki*; Ishikawa, Yoshihisa*; Kofu, Maiko; Lee, S. H.*; Kumigashira, Hiroshi*; Hu, C. S.*; Qi, Z. M.*; et al.

Physical Review B, 98(9), p.094305_1 - 094305_7, 2018/09

 Times Cited Count:5 Percentile:39.54(Materials Science, Multidisciplinary)

Using angle-resolved photoemission spectroscopy and inelastic neutron scattering, we have studied how electronic structures and lattice dynamics evolve with temperature in Na-doped SnSe.

Journal Articles

Self-learning Monte Carlo method; Continuous-time algorithm

Nagai, Yuki; Shen, H.*; Qi, Y.*; Liu, J.*; Fu, L.*

Physical Review B, 96(16), p.161102_1 - 161102_6, 2017/10

 Times Cited Count:43 Percentile:91.96(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Precise determination of $$^{12}_{Lambda}$$C level structure by $$gamma$$-ray spectroscopy

Hosomi, Kenji; Ma, Y.*; Ajimura, Shuhei*; Aoki, Kanae*; Dairaku, Seishi*; Fu, Y.*; Fujioka, Hiroyuki*; Futatsukawa, Kenta*; Imoto, Wataru*; Kakiguchi, Yutaka*; et al.

Progress of Theoretical and Experimental Physics (Internet), 2015(8), p.081D01_1 - 081D01_8, 2015/08

 Times Cited Count:13 Percentile:70.14(Physics, Multidisciplinary)

Level structure of the $$^{12}_{Lambda}$$C hypernucleus was precisely determined by means of $$gamma$$-ray spectroscopy. We identified four $$gamma$$-ray transitions via the $$^{12}$$C$$(pi^{+},K^{+}gamma)$$ reaction using a germanium detector array, Hyperball2. The spacing of the ground-state doublet $$(2^{-}, 1^{-}_{1})$$ was measured to be $$161.5pm0.3$$(stat)$$pm0.3$$ (syst)keV from the direct $$M1$$ transition. Excitation energies of the $$1^{-}_{2}$$ and $$1^{-}_{3}$$ states were measured to be $$2832pm3pm4$$, keV and $$6050pm8pm7$$, keV, respectively. The obtained level energies provide definitive references for the reaction spectroscopy of $$Lambda$$ hypernuclei.

Journal Articles

Hydroxyl radical, sulfate radical and nitrate radical reactivity towards crown ethers in aqueous solutions

Wan, L. K.*; Peng, J.*; Lin, M.; Muroya, Yusa*; Katsumura, Yosuke*; Fu, H. Y.*

Radiation Physics and Chemistry, 81(5), p.524 - 530, 2012/05

 Times Cited Count:15 Percentile:78.3(Chemistry, Physical)

Rate constants of common crown ethers ((C$$_{2}$$H$$_{4}$$O)$$_{n}$$, n=4, 5, 6) and their model compound, 1,4-dioxane(6C2) with some important oxidative radicals, $$^{cdot}$$OH, SO$$_{4}^{cdot-}$$, and NO$$_{3}^{cdot}$$ were determined in various aqueous solutions using pulse radiolysis and laser photolysis techniques. The rate constants for 6C2 and crown ethers with $$^{cdot}$$OH and SO$$_{4}^{cdot-}$$ increase with the number of H-atom in the ethers, indicating that H-abstraction is dominant reaction between crown ethers and these two radicals. The presence of cations in solution has negligible effect on the rate constants for $$^{cdot}$$OH and SO$$_{4}^{cdot-}$$. However, for NO$$_{3}^{cdot}$$, the rate constants is not in proportional to H-atom number in crown ethers, and the 12-crown-4 is most reactive compared with the others. For the studied crown ethers, the rate constants of these oxidative radicals have the order: $$^{cdot}$$OH $$>$$ SO$$_{4}^{cdot-}$$ $$>$$ NO$$_{3}^{cdot}$$. This is the first report on the kinetic behavior of crown ethers with NO$$_{3}^{cdot}$$, and it would be helpful for the understanding of stability of crown ethers in the nuclear fuel reprocessing.

Journal Articles

Pulse radiolysis studies of intermolecular charge transfers involving tryptophan and three-electron-bonded intermediates derived from methionine

Fu, H. Y.*; Lin, M.; Muroya, Yusa*; Katsumura, Yosuke*

Research on Chemical Intermediates, 38(1), p.135 - 145, 2012/01

 Times Cited Count:2 Percentile:3.5(Chemistry, Multidisciplinary)

In the present work, pulse radiolysis was used to demonstrate the oxidizing nature of various intermediates of $$N$$-AcMetNH$$_{2}$$ and $$N$$-AcMetOMe via the oxidation of tryptophan (Trp) in a free aqueous solution. The reaction was examined at different pH levels. Electron transfer processes involving Trp and the sulfur-containing three-electron-bonded intermediates were investigated. The results revealed that Trp-Met pairs can form very favorable redox couples in biological systems, which is consistent with earlier reports of more efficient and rapid intramolecular charge transfers in synthetic as well as natural peptides containing methionine (Met).

Journal Articles

Free-radical scavenging activities of silybin and its analogues; A Pulse radiolysis study

Fu, H. Y.*; Lin, M.; Katsumura, Yosuke*; Muroya, Yusa*

International Journal of Chemical Kinetics, 43(10), p.590 - 597, 2011/10

 Times Cited Count:1 Percentile:2.08(Chemistry, Physical)

Free radical scavenging and antioxidant activities of four natural flavonoids, namely silybin, naringenin, naringin and hesperetin, have been studied using nanosecond pulse radiolysis techniques. The kinetics and mechanisms of the reactions of silybin and analogues with various oxidizing radicals have been investigated. Further, the transient species has been assigned and radical scavenging rate constants have also been measured. Moreover, the structure-activity relationships (SAR) between chemical structures of the flavonoids and their radical scavenging activities are further analyzed by theoretical calculation. Combined our previous observation of the fast reparation of DNA damage and efficient DNA protection against radiation damage in vitro, it can be confirmed that test flavonoids are promising molecules to be used for their potential antioxidant properties.

Journal Articles

Nitration activates tyrosine toward reaction with the hydrated electron

Shi, W.-Q.*; Fu, H.-Y.*; Bounds, P. L.*; Muroya, Yusa*; Lin, M.; Katsumura, Yosuke*; Zhao, Y.-L.*; Chai, Z.-F.*

Radiation Research, 176(1), p.128 - 133, 2011/07

 Times Cited Count:3 Percentile:19.48(Biology)

3-Nitrotyrosine (3-NT) has been reported as an important biomarker of oxidative stress and potential source of reactive oxygen species (ROSs). In this work, the UV-visible absorption spectra of the transients formed by hydrated electron (e$$_{rm aq}$$$$^{-}$$) reacting with 3-NT and its derivatives were investigated, the spectra showed many characteristics of aromatic nitro anion radical. The reaction rate constants of e$$_{rm aq}$$$$^{-}$$ reacting with 3-NT, N-acetyl-3-nitrotyrosine ethyl ester (NANTE) and nitrotyrosine-containing peptide Gly-nitroTyr-Gly at neutral pH were determined, respectively, which were almost two orders of magnitude higher than that of tyrosine and tyrosine-containing peptides. The pH-dependence of e$$_{rm aq}$$$$^{-}$$ decay rate constants in presence of 3-NT was also studied.

Journal Articles

Temperature dependent absorption spectra of Br$$^{-}$$, Br$$_{2}$$$$^{.-}$$, and Br$$_{3}$$$$^{-}$$ in aqueous solutions

Lin, M.; Archirel, P.*; Van-Oanh, N. T.*; Muroya, Yusa*; Fu, H.*; Yan, Y.*; Nagaishi, Ryuji; Kumagai, Yuta; Katsumura, Yosuke*; Mostafavi, M.*

Journal of Physical Chemistry A, 115(17), p.4241 - 4247, 2011/04

 Times Cited Count:12 Percentile:43.18(Chemistry, Physical)

The absorption spectra of Br$$_{2}$$$$^{.-}$$ and Br$$_{3}$$$$^{-}$$ in aqueous solutions are investigated by pulse radiolysis techniques from room temperature to 380 and 350$$^{circ}$$C, respectively. The weak temperature effect on the absorption spectra of Br$$_{2}$$$$^{.-}$$ and Br$$_{3}$$$$^{-}$$ is because in these two systems, the transition occurs between two valence states. We performed classical dynamics of hydrated Br$$^{-}$$ system at 20 and 300$$^{circ}$$C under pressure of 25 MPa. This shows that the first water shell is strongly bound to the anion whatever the temperature. The first two water shells form a cavity of a roughly spherical shape around the anion. By TDDFT method, we calculated the absorption spectra of hydrated Br$$^{-}$$ at two temperatures and we compared the results with the experimental data.

Journal Articles

Pulse radiolysis study on free radical scavenger edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one), 2; A Comparative study on edaravone derivatives

Hata, Kuniki; Lin, M.; Katsumura, Yosuke*; Muroya, Yusa*; Fu, H. Y.*; Yamashita, Shinichi; Nakagawa, Hidehiko*

Journal of Radiation Research, 52(1), p.15 - 23, 2011/01

 Times Cited Count:18 Percentile:61.61(Biology)

Journal Articles

Solvated electrons at elevated temperatures in different alcohols; Temperature and molecular structure effects

Yan, Y.*; Lin, M.; Katsumura, Yosuke*; Fu, H.*; Muroya, Yusa*

Radiation Physics and Chemistry, 79(12), p.1234 - 1239, 2010/12

 Times Cited Count:1 Percentile:11(Chemistry, Physical)

The absorption spectra of solvated electrons in various alcohols were measured at different temperatures using pulse radiolysis technique, and then compared with currently available experimental data on the temperature dependent energy of absorption maximum $$E$$$$_{rm max}$$ of solvated electrons in monohydric alcohols, diols and triol. $$E$$$$_{rm max}$$ is larger in those alcohols having more OH groups at all the temperatures. The molecular structure effect, including OH numbers, OH position and carbon chain length, are investigated. For the primary alcohols with same OH group number and position, the temperature coefficient increases with increasing chain length. For the alcohols with same chain length and OH numbers, the temperature coefficient is larger for the symmetric alcohols than the asymmetric ones.

Journal Articles

Protective effects of silybin and analogues against X-ray radiation-induced damage

Fu, H. Y.*; Lin, M.; Katsumura, Yosuke*; Yokoya, Akinari; Hata, Kuniki; Muroya, Yusa*; Fujii, Kentaro; Shikazono, Naoya

Acta Biochimica et Biophysica Sinica, 42(7), p.489 - 495, 2010/07

 Times Cited Count:11 Percentile:32.4(Biochemistry & Molecular Biology)

Silybin (SLB) and similar analogues, namely, hesperetin (HESP), naringenin (NAN) and naringin (NAR), are believed to be active constituents of natural flavonoids that have been reported as chemopreventive agents for certain cancers. Moreover, SLB and analogues have been determined to fast repair DNA bases from oxidative damage by pulse radiolysis techniques. The present study was designed to evaluate the protective effects of SLB and analogues on soft X-ray-induced damage to plasmid DNA in vitro. Among the compounds tested, HESP and SLB were the most effective in preventing X-ray-induced formation of DNA single-strand breaks (SSB). A comparison of these results with other experiments showed that the ability of SLB and analogues to inhibit DNA damage in vitro correlated with the ability of the compounds to scavenge free radicals. Our work revealed that natural flavonoids, SLB and analogues may be used as potent protectors against radiation damage.

Journal Articles

Pulse radiolysis studies on the temperature-dependent spectrum and the time-dependent yield of solvated electron in Propane-1,2,3-triol

Lin, M.; Fu, H.*; Lampre, I.*; De Waele, V.*; Muroya, Yusa*; Yan, Y.*; Yamashita, Shinichi; Katsumura, Yosuke; Mostafavi, M.*

Journal of Physical Chemistry A, 113(44), p.12193 - 12198, 2009/10

 Times Cited Count:7 Percentile:24.43(Chemistry, Physical)

With a revisit of the absorption coefficient of the solvated electron in propane-1,2,3-triol, the temperature dependent behavior of the absorption spectrum of solvated electron was studied from room temperature to 573 K by pulse radiolysis techniques. The change in the absorption spectrum of solvated electron in propane-1,2,3-triol observed by cooling down from a high temperature to 333 K is compared with that occurring during the electron solvation process at 333 K. The effect of the specific molecular structure of propane-1,2,3-triol compared to other alcohols is discussed.

Journal Articles

Free radical scavenging reactions and antioxidant activities of silybin; Mechanistic aspects and pulse radiolytic studies

Fu, H. Y.*; Lin, M.; Muroya, Yusa*; Hata, Kuniki; Katsumura, Yosuke; Yokoya, Akinari; Shikazono, Naoya; Hatano, Yoshihiko

Free Radical Research, 43(9), p.887 - 897, 2009/09

 Times Cited Count:24 Percentile:50.89(Biochemistry & Molecular Biology)

Journal Articles

Alf$'e$n eigenmodes driven by Alf$'e$nic beam ions in JT-60U

Shinohara, Koji; Kusama, Yoshinori; Takechi, Manabu; Morioka, Atsuhiko; Ishikawa, Masao*; Oyama, Naoyuki; Tobita, Kenji; Ozeki, Takahisa; Takeji, Satoru; Moriyama, Shinichi; et al.

Nuclear Fusion, 41(5), p.603 - 612, 2001/05

 Times Cited Count:78 Percentile:90.62(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Fast particle experiments in JT-60U

Kramer, G. J.; Iwase, Makoto; Kusama, Yoshinori; Morioka, Atsuhiko; Nemoto, Masahiro; Nishitani, Takeo; Shinohara, Koji; Takeji, Satoru; Tobita, Kenji; Ozeki, Takahisa; et al.

Nuclear Fusion, 40(7), p.1383 - 1396, 2000/07

 Times Cited Count:44 Percentile:78.44(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Characteristics of Alfv$'e$n eigenmodes, burst modes and chirping modes in the Alfv$'e$n frequency range driven by negative ion based neutral beam injection in JT-60U

Kusama, Yoshinori; Kramer, G. J.; Kimura, Haruyuki; Saigusa, Mikio*; Ozeki, Takahisa; Tobita, Kenji; Oikawa, Toshihiro; Shinohara, Koji; Kondoh, Takashi; Moriyama, Shinichi; et al.

Nuclear Fusion, 39(11Y), p.1837 - 1843, 1999/11

 Times Cited Count:63 Percentile:87.19(Physics, Fluids & Plasmas)

no abstracts in English

48 (Records 1-20 displayed on this page)