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Sakamaki, Tatsuya*; Suzuki, Akio*; Otani, Eiji*; Terasaki, Hidenori*; Urakawa, Satoru*; Katayama, Yoshinori; Funakoshi, Kenichi*; Wang, Y.*; Hernlund, J. W.*; Ballmer, M. D.*
Nature Geoscience, 6(12), p.1041 - 1044, 2013/12
Times Cited Count：156 Percentile：97.04(Geosciences, Multidisciplinary)The bounday between Earth's rigid lighosphere and the underlying, ductile ashenosphere is marked by a distinct siseismic discontinuity. We measure the density, viscosity and structure of basaltic magmas using high-pressure and high-temperature experiments and in situ X-ray analysis under pressure of up to 5.5 GPa. We find that the magmas rapidly become denser with increasing presure and show a viscosity minimum near 4 GPa. Magma mobility determined by the density and viscosity data exhibits a peak at pressures corresponding to depths of 120-150 km, within the asthenosphere. The diminishing mobility of magma in Earth's asthenosphere as the mlets ascend could lead to excessive melt accumulation at depths of 80-100 km, at the lithosphere-asthenosphere boundary. It is concluded that the observed seismic discontinuity at the lithosphere-asthenosphere boundary records this accumulation of melt.
Shiraki, Fumiya*; Yoshikawa, Taeko*; Oshima, Akihiro*; Oshima, Yuji*; Takasawa, Yuya*; Fukutake, Naoyuki*; Oyama, Tomoko*; Urakawa, Tatsuya*; Fujita, Hajime*; Takahashi, Tomohiro*; et al.
Nuclear Instruments and Methods in Physics Research B, 269(15), p.1777 - 1781, 2011/08
Times Cited Count：8 Percentile：50.36(Instruments & Instrumentation)The graded energy deposition of heavy ion beam irradiation to polymeric materials was utilized to synthesize a novel proton exchange membrane (PEM) with the graded density of sulfonic acid groups toward the thickness direction. Stacked Poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP) films were irradiated by Xe
ion beam with the energy of 6 MeV/u under a vacuum condition. Irradiated films were grafted with styrene monomer and then sulfonated. The membrane electrode assembly (MEA) fabricated by the function graded PEM showed improved fuel cell performance in terms of voltage stability. It was expected that the function-graded PEM could control the graded concentration of sulfonic acid groups in PEM.
Nishida, Keisuke*; Otani, Eiji*; Urakawa, Satoru*; Suzuki, Akio*; Sakamaki, Tatsuya*; Terasaki, Hidenori*; Katayama, Yoshinori
American Mineralogist, 96(5-6), p.864 - 868, 2011/05
Times Cited Count：34 Percentile：66.85(Geochemistry & Geophysics)The density of liquid iron sulfide (FeS) was measured up to 3.8 GPa and 1800 K using the X-ray absorption method. The compression curve of the liquid FeS can be fitted using the Vinet equation of state. Isothermal bulk modulus and its temperature and pressure derivatives were determined by a non-linear least squares fit. Liquid FeS is more compressible than Fe-rich Fe-S liquid.
Sakamaki, Tatsuya*; Otani, Eiji*; Urakawa, Satoru*; Terasaki, Hidenori*; Katayama, Yoshinori
American Mineralogist, 96(4), p.553 - 557, 2011/04
Times Cited Count：33 Percentile：65.90(Geochemistry & Geophysics)The density of carbonated peridotite magma was measured up to 3.8 GPa and 2100 K using an X-ray absorption method. The bulk modulus of carbonated peridotite magma is larger than that of hydrous peridotite magma. The partial molar volume of CO
in magma under high pressure and temperature conditions was calculated. Our results show that the partial molar volume of CO is less compressible than that of HO, suggesting that, on an equal molar basis, CO is more effective than HO in reducing peridotite melt density at high pressure.
Gowa, Tomoko*; Shiotsu, Tomoyuki*; Urakawa, Tatsuya*; Oka, Toshitaka; Murakami, Takeshi*; Oshima, Akihiro*; Hama, Yoshimasa*; Washio, Masakazu*
Radiation Physics and Chemistry, 80(2), p.264 - 267, 2011/02
Times Cited Count：11 Percentile：60.70(Chemistry, Physical)High linear energy transfer (LET) heavy ion beams were irradiated to poly(tetrafluoroethylene-co-ethylene) (ETFE) under vacuum and in air. The irradiation effects in ETFE as a function of the depth was precisely evaluated by analyzing each one of the films of the irradiation samples which were made of stacked ETFE films. It was indicated that conjugated double bonds would be generated by heavy ion beam irradiation, and their amounts should show the Bragg-curve-like distributions. Also, it was suggested that higher LET beams would induce radical formation in high density and longer conjugated C=C double bonds could be generated by the second-order reactions. Moreover, for irradiation samples in air, C=O was produced correlating to the yield of oxygen molecules diffusing from the sample surface.
Sakamaki, Tatsuya*; Otani, Eiji*; Urakawa, Satoru*; Suzuki, Akio*; Katayama, Yoshinori; Zhao, D.*
Earth and Planetary Science Letters, 299(3-4), p.285 - 289, 2010/11
Times Cited Count：31 Percentile：59.28(Geochemistry & Geophysics)The density of the Apollo 14 black glass melt, which has the highest TiO content of pristine mare glasses, was measured to 4.8 GPa and 2100 K using an X-ray absorption method. A fit of the pressure-density-temperature data to the high-temperature Birch-Murnaghan equation of state yielded the isothermal bulk modulus, its pressure derivative, and the temperature derivative of the bulk modulus. Implication for heterogeneities in the lunar mantle is discussed.
Sakamaki, Tatsuya*; Otani, Eiji*; Urakawa, Satoru*; Suzuki, Akio*; Katayama, Yoshinori
American Mineralogist, 95(1), p.144 - 147, 2010/01
Times Cited Count：39 Percentile：70.75(Geochemistry & Geophysics)The density of a peridotite magma was measured up to 2.5 GPa and 2300 K using an X-ray absorption method. The method allowed measurement of the density of a peridotite melt under seven different conditions and clarified the pressure and temperature dependence of the density. A fit of the pressure-density-temperature data to the high-temperature Birch-Murnaghan equation of state yielded the isothermal bulk modulus, 
GPa, its pressure derivative, 
, and the derivative of bulk modulus 
GPa/K at 2100 K. The large bulk modulus and its pressure derivative of the peridotite melt compared with that of basaltic melt is consistent with previous results from sink-float experiments.
Sakamaki, Tatsuya*; Otani, Eiji*; Urakawa, Satoru*; Suzuki, Akio*; Katayama, Yoshinori
Earth and Planetary Science Letters, 287(3-4), p.293 - 297, 2009/10
Times Cited Count：63 Percentile：79.35(Geochemistry & Geophysics)The density of hydrous peridotite magma containing 5wt.% HO was measured at pressures and temperatures up to 4.3 GPa and 2073 K, respectively, using the X-ray absorption method. A fit of pressure-density-temperature data to the high-temperature Birch-Murnagan equation of state yields isothermal bulk modulus 
GPa, its pressure derivative 
and the temperature derivative of the bulk modulus 
GPa/K at 1773K. The small bulk modulus of the hydrous peridotite magma compared with that of the dry peridotite magma reflects the effect of water, which is more compressible than the silicate melt.
Gowa, Tomoko*; Shiotsu, Tomoyuki*; Urakawa, Tatsuya*; Oka, Toshitaka; Murakami, Takeshi*; Oshima, Akihiro*; Hama, Yoshimasa*; Washio, Masakazu*
no journal, ,
Takasawa, Yuya*; Fukutake, Naoyuki*; Takahashi, Tomohiro*; Urakawa, Tatsuya*; Oshima, Yuji*; Gowa, Tomoko*; Shiraki, Fumiya*; Fujita, Hajime*; Oka, Toshitaka; Murakami, Takeshi*; et al.
no journal, ,
