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Journal Articles

Horizontal line nodes in Sr$$_2$$RuO$$_4$$ proved by spin resonance

Iida, Kazuki*; Kofu, Maiko; Suzuki, Katsuhiro*; Murai, Naoki; Kawamura, Seiko; Kajimoto, Ryoichi; Inamura, Yasuhiro; Ishikado, Motoyuki*; Hasegawa, Shunsuke*; Masuda, Takatsugu*; et al.

Journal of the Physical Society of Japan, 89(5), p.053702_1 - 053702_5, 2020/05

 Times Cited Count:1 Percentile:24.83(Physics, Multidisciplinary)

Journal Articles

Turbulence intensity profile in high Reynolds number pipe flow

Wada, Yuki; Furuichi, Noriyuki*; Kusano, Eisuke*; Tsuji, Yoshiyuki*

Proceedings of 11th International Symposium on Turbulence and Shear Flow Phenomena (TSFP-11) (Internet), 6 Pages, 2019/07

This paper reports characteristics of turbulence intensity profile obtained in high Reynolds number actual flow facility in Japan. The experiments were performed in a pipe flow with water, and the friction Reynolds number was varied up to $$Re_{tau}$$ = 2.0 $$times$$ 10$$^{4}$$. The streamwise velocity was measured by laser Doppler velocimetry (LDV). The new procedure to correct the measurement volume effect of LDV is suggested and we discuss turbulence intensity issues such as the inner peak Reynolds number dependence and the outer logarithmic behavior, it was found that these characteristic behaviors are consistent with previous turbulence studies.

Journal Articles

A Correction method based on probability density function and measurement volume for turbulence intensity profile measured by LDV in turbulent pipe flow

Wada, Yuki; Furuichi, Noriyuki*; Kusano, Eisuke*; Tsuji, Yoshiyuki*

Proceedings of 15th International Conference on Flow Dynamics (ICFD 2018) (USB Flash Drive), p.778 - 779, 2018/11

Spatial resolution effect of LDV (Laser Doppler Velocimetry) on the time-averaged statistics is presented in high Reynolds number turbulent pipe flow. Employing PDF (Probability Density Function) of streamwise velocity, we report the study of overestimation of time-averaged statistics based on the size of measurement volume. We proposed a simple equation to estimate their spatial resolution effect. Using the proposed equation, the measurement position and the measurement volume calculated precisely based on experimental setup, it was found that the correction for spatial resolution effect is possible. Analyzing the pipe flow data measured by LDV, we estimated the expected turbulence intensity profile. The validity of the present correction method was confirmed by comparing the correction result based on the low-resolution experimental result with the high-resolution experimental result.

Journal Articles

Speciation of ruthenium(III) chloro complexes in hydrochloric acid solutions and their extraction characteristics with an amide-containing amine compound

Suzuki, Tomoya*; Ogata, Takeshi*; Tanaka, Mikiya*; Kobayashi, Toru; Shiwaku, Hideaki; Yaita, Tsuyoshi; Narita, Hirokazu*

Metals, 8(7), p.558_1 - 558_10, 2018/07

 Times Cited Count:5 Percentile:39.76(Materials Science, Multidisciplinary)

The refining of platinum group metals is based mainly on solvent extraction methods, whereas Ru is selectively recovered by distillation as RuO$$_4$$. Replacement of distillation byextraction is expected to simplify the purification process. To develop an effective extraction system for Ru, we analyzed the Ru species in HCl with UV-Vis and EXAFS spectroscopies, and we examined the properties of Ru extracted with N-2-ethylhexyl-bis(N-di-2-ethylhexyl-ethylamide) amine (EHBAA). EXAFS and UV-Vis spectra of Ru in HCl solutions revealed that the predominant Ru species in 0.5-10 M HCl solutions changed from [RuCl$$_4$$(H$$_2$$O)$$_2$$]$$^-$$ to [RuCl$$_6$$]$$^3$$$$^-$$ with the HCl concentration. The extraction percentages of Ru in the EHBAA system increased with increasing HCl concentration, reached 80% at [HCl] = 5 M, and decreased athigher HCl concentrations. EXAFS analysis of the extracted complex indicated that the Ru$$^3$$$$^+$$ had 5 Cl$$^-$$ and 1 H$$_2$$O in its inner coordination sphere. The similarity of the dependence on HCl concentrations of the extraction in the EHBAA system and the distribution profile of [RuCl$$_5$$(H$$_2$$O)]$$^2$$$$^-$$ on [RuCl$$_n$$(H$$_2$$O)$$_6$$$$_-$$$$_n$$]$$^3$$$$^-$$$$^n$$ suggested that the EHBAA extracted the pentachlorido species.

Journal Articles

Further experiments for mean velocity profile of pipe flow at high Reynolds number

Furuichi, Noriyuki*; Terao, Yoshiya*; Wada, Yuki; Tsuji, Yoshiyuki*

Physics of Fluids, 30(5), p.055101_1 - 055101_7, 2018/05

 Times Cited Count:0 Percentile:100(Mechanics)

Journal Articles

Photo-oxidative doping in $$pi$$-conjugated zig-zag chain of carbon atoms with sulfur-functional group

Ikeura, Hiromi*; Sekiguchi, Tetsuhiro

Applied Physics Letters, 111(23), p.231605_1 - 231605_4, 2017/12

 Times Cited Count:0 Percentile:100(Physics, Applied)

Photo-oxidative doping processes were studied for the trans-polyacetylene (PA) backbone with the -SCH$$_{3}$$ side group as a chemically representative of the S-functionalized zig-zag graphene nanoribbon edge. Sulfur K-edge X-ray absorption near edge structure (XANES) spectroscopy indicates that photochemical reaction of S-CH$$_{3}$$ with atmospheric O$$_{2}$$ forms selectively oxidized products such as -S(O)CH$$_{3}$$ and -SO$$_{3}$$$$^{-}$$ bound to the (PA) backbone. Using the correlation between the oxidation states of sulfur and the XANES peak positions, the partial charge distribution of CH$$_{3}$$S$$^{delta+}$$ -PA$$^{delta-}$$ has been estimated. The results can provide some strategy for area-selective and controllable doping processes of atomic-scale molecular systems with the assistance of UV light.

Journal Articles

Comparison of the extractabilities of tetrachloro- and tetrabromopalladate(II) ions with a thiodiglycolamide compound

Narita, Hirokazu*; Maeda, Motoki*; Tokoro, Chiharu*; Suzuki, Tomoya*; Tanaka, Mikiya*; Motokawa, Ryuhei; Shiwaku, Hideaki; Yaita, Tsuyoshi

Analytical Sciences, 33(11), p.1305 - 1309, 2017/11

 Times Cited Count:3 Percentile:76.11(Chemistry, Analytical)

Journal Articles

Spin resonance in the new-structure-type iron-based superconductor CaKFe$$_{4}$$As$$_{4}$$

Iida, Kazuki*; Ishikado, Motoyuki*; Nagai, Yuki; Yoshida, Hiroyuki*; Christianson, A. D.*; Murai, Naoki; Kawashima, Kenji*; Yoshida, Yoshiyuki*; Eisaki, Hiroshi*; Iyo, Akira*

Journal of the Physical Society of Japan, 86(9), p.093703_1 - 093703_4, 2017/09

 Times Cited Count:18 Percentile:13.2(Physics, Multidisciplinary)

Journal Articles

Non-aqueous selective synthesis of orthosilicic acid and its oligomers

Igarashi, Masayasu*; Matsumoto, Tomohiro*; Yagihashi, Fujio*; Yamashita, Hiroshi*; Ohara, Takashi; Hanashima, Takayasu*; Nakao, Akiko*; Moyoshi, Taketo*; Sato, Kazuhiko*; Shimada, Shigeru*

Nature Communications (Internet), 8, p.140_1 - 140_8, 2017/07

 Times Cited Count:5 Percentile:63.43(Multidisciplinary Sciences)

Journal Articles

Recent research in solvent extraction of platinum group metals

Narita, Hirokazu*; Suzuki, Tomoya*; Motokawa, Ryuhei

Nippon Kinzoku Gakkai-Shi, 81(4), p.157 - 167, 2017/04

 Times Cited Count:3 Percentile:66.31(Metallurgy & Metallurgical Engineering)

Journal Articles

Selective extraction of Pt(IV) over Fe(III) from HCl with an amide-containing tertiary amine compound

Maeda, Motoki*; Narita, Hirokazu*; Tokoro, Chiharu*; Tanaka, Mikiya*; Motokawa, Ryuhei; Shiwaku, Hideaki; Yaita, Tsuyoshi

Separation and Purification Technology, 177, p.176 - 181, 2017/04

 Times Cited Count:8 Percentile:52.37(Engineering, Chemical)

Journal Articles

The Role of low-temperature organic matter diagenesis in carbonate precipitation within a marine deposit

Miyakawa, Kazuya; Ishii, Eiichi; Hirota, Akinari*; Komatsu, Daisuke*; Ikeya, Kosuke*; Tsunogai, Urumu*

Applied Geochemistry, 76, p.218 - 231, 2017/01

 Times Cited Count:8 Percentile:37.13(Geochemistry & Geophysics)

no abstracts in English

Journal Articles

Elastically-homogeneous lattice models of damage in geomaterials

Asahina, Daisuke*; Aoyagi, Kazuhei; Kim, K.*; Birkholzer, J.*; Birkholzer, J. T.*; Bolander, J. E.*

Computers and Geotechnics, 81, p.195 - 206, 2017/01

 Times Cited Count:19 Percentile:9.08(Computer Science, Interdisciplinary Applications)

Journal Articles

Small-angle neutron scattering study of specific interaction and coordination structure formed by mono-acetyl-substituted dibenzo-20-crown-6-ether and cesium ions

Motokawa, Ryuhei; Kobayashi, Toru; Endo, Hitoshi*; Ikeda, Takashi; Yaita, Tsuyoshi; Suzuki, Shinichi; Narita, Hirokazu*; Akutsu, Kazuhiro*; Heller, W. T.*

Journal of Nuclear Science and Technology, 53(8), p.1205 - 1211, 2016/08

 Times Cited Count:0 Percentile:100(Nuclear Science & Technology)

Journal Articles

Method of dynamic image measurement for analyzing cricket behavior

Takahashi, Satoru*; Okuda, Yasutake*; Kawabata, Kuniaki; Aonuma, Hitoshi*; Sato, Yutaka*; Iwata, Kenji*

Journal of Signal Processing, 20(2), p.65 - 74, 2016/03

Journal Articles

Observation of oriented organic semiconductor using Photo-Electron Emission Microscope (PEEM) with polarized synchrotron

Sekiguchi, Tetsuhiro; Baba, Yuji; Hirao, Norie; Honda, Mitsunori; Izumi, Toshinori; Ikeura, Hiromi*

Molecular Crystals and Liquid Crystals, 622(1), p.44 - 49, 2015/12


 Times Cited Count:0 Percentile:100(Chemistry, Multidisciplinary)

The molecular orientation is one of the important factors for controlling various properties in organic semiconductor materials. Films are usually heterogeneous. Thus they exist as a mixture of microscopic domains which have a variety of orientation directions. Therefore, it is essential to observe selectively microscopic domains with different orientation direction. In this work, we have developed the photoelectron emission microscopy (PEEM) system combined with the linearly polarized vacuum ultraviolet (VUV) light or synchrotron radiation (SR) X-rays. PEEM images (FOV = ca.50 micro m) for poly(3-hexylthiophene), P3HT thin films were observed under the UV irradiation with various polarization angles, including in-plain and out-of-plain polarization. Morphologies at some bright parts are different each other. The resultant observation suggests that it enables us to distinguish oriented micro-domains with specific directions of polymer chain axis from other amorphous parts.

Journal Articles

Electronic properties of 6,13-Bis(triisopropylsilylethynyl)pentacene probed by inner-shell spectroscopy

Ikeura, Hiromi*; Sekiguchi, Tetsuhiro

Molecular Crystals and Liquid Crystals, 622(1), p.50 - 54, 2015/12

 Times Cited Count:0 Percentile:100(Chemistry, Multidisciplinary)

Organic electrically conducting $$pi$$-stacked molecules are widely regarded as promising materials for future application of nanoelectronics. Direct measurements of electronic structures of unoccupied states in organic semiconductors lead to better understanding of mechanism of electron conduction. For probing unoccupied partial density of states (DOS), X-ray absorption spectroscopy (XAS) is commonly used, where selective excitation of the 1s core electron to the unoccupied conduction band is possible. However, XAS cannot distinguish localized and delocalized features without comparing any theoretical approach. In this work, the core-hole-clock method in resonant Auger spectroscopy (RAS) has been applied to probe electron delocalization through the empty conduction band in the attosecond domain for the purpose of exploring electronic materials with high-speed electron transport. We will discuss some organic molecules such as pentacenes.

Journal Articles

Investigation of unoccupied electronic states near the fermi level of polysilane using resonant Auger spectroscopy

Ogawa, Hiroshi*; Ikeura, Hiromi*; Sekiguchi, Tetsuhiro

Molecular Crystals and Liquid Crystals, 622(1), p.164 - 169, 2015/11

 Times Cited Count:0 Percentile:100(Chemistry, Multidisciplinary)

Unoccupied electronic states near the Fermi level of poly(dimethylsilane) were probed using Si 1s X-ray absorption spectroscopy (XAS) and Si KL$$_{2,3}$$L$$_{2,3}$$ resonant Auger spectroscopy (RAS). The measured resonance peaks of XAS spectra near Si K-edge have been assigned in comparison with the discrete variational (DV)-X$$alpha$$ molecular orbital calculations. The rapid delocalization of Si 1s core-excited electron through the empty conduction band was observed along the polymer chain with the energy dependent RAS measurement, and the electron delocalization time was estimated based on the core-hole clock method.

Journal Articles

Fabrication of hard-coated optical absorbers with microstructured surfaces using etched ion tracks; Toward broadband ultra-low reflectance

Amemiya, Kuniaki*; Koshikawa, Hiroshi; Yamaki, Tetsuya; Maekawa, Yasunari; Shitomi, Hiroshi*; Numata, Takayuki*; Kinoshita, Kenichi*; Tanabe, Minoru*; Fukuda, Daiji*

Nuclear Instruments and Methods in Physics Research B, 356-357, p.154 - 159, 2015/08

 Times Cited Count:5 Percentile:53.24(Instruments & Instrumentation)

Broadband low reflectance materials have various applications in the field of optical energy management; however, materials with ultra-low reflectance (below 0.1%) have been considered as mechanically delicate. We have developed a novel hard-surface optical absorber with microstructured, diamond-like carbon coated ion tracks on CR-39 plastic substrate. The spectral reflectance of the first prototype was below 2% for wavelengths ranging from 400 nm to 1400 nm; moreover, the optical absorber had mechanically hard surface and exhibited temporal durability. Choosing the appropriate design of the surface structure and coating layer is likely to reduce the reflectance to the order of 0.1%. This technique yields easy-to-handle broadband ultra-low reflectance absorbers.

Journal Articles

Temperature of thermal spikes in amorphous silicon nitride films produced by 1.11 MeV C$$_{60}^{3+}$$ impacts

Kitayama, Takumi*; Nakajima, Kaoru*; Suzuki, Motofumi*; Narumi, Kazumasa; Saito, Yuichi; Matsuda, Makoto; Sataka, Masao*; Tsujimoto, Masahiko*; Isoda, Shoji*; Kimura, Kenji*

Nuclear Instruments and Methods in Physics Research B, 354, p.183 - 186, 2015/07

 Times Cited Count:2 Percentile:73.66(Instruments & Instrumentation)

267 (Records 1-20 displayed on this page)