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Yoshiaki Kinemuchi Ken-ichi Mimura Atsuya Towata Kazumi Kato 《Journal of Electronic Materials》2014,43(6):2011-2016
A giant Seebeck coefficient of ?890 μV/K at 500 °C has been observed in Y0.2Sr0.8TiO3 prepared using nanocubes. Doping rare earth elements, RE, has revealed that small RE is effective to enhance the Seebeck coefficient. Through soft mode observations by Raman spectroscopy and structural calculations based on density functional theory, it has been found that the breakdown of inversion symmetry of the perovskite structure near the surface of nanocubes can be recovered by doping with small RE. Because the dielectric constant is strongly related to the surface structure in this compound, we suggest that RE doping modulates the potential barrier at the grain boundary, resulting in a pronounced energy filtering effect in Y doped SrTiO3. 相似文献
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Tatsuo Noritake Kazutoshi Miwa Masakazu Aoki Mitsuru Matsumoto Shin-ichi Towata Hai-Wen Li Shin-ichi Orimo 《International Journal of Hydrogen Energy》2013
Complex hydride Mg(BH4)(NH2), which consists of double anion BH4− and NH2−, was synthesized and the crystal structure was analyzed by synchrotron X-ray diffraction. The mixture sample of Mg(BH4)2 + Mg(NH2)2 prepared by ball milling was reacted and crystallized to Mg(BH4)(NH2) by heating at about 453 K. This crystal phase transforms into amorphous phase above 473 K and subsequently the dehydrogenation begins. The crystal structure of Mg(BH4)(NH2) was determined from measurement data at 453 K (chemical formula: Mg0.94(BH4)1(NH2)0.88, crystal system: tetragonal, space group: I41 (No.80), Z = 8, lattice constants: a = 5.814(1), c = 20.450(4) Å at 453 K). Mg(BH4)(NH2) is ionic crystal which the cation (Mg2+) and the anions (BH4− and NH2−) are stacking alternately along the c-axis direction. Two BH4− and two NH2− tetrahedrally coordinate around Mg2+ ion. 相似文献
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Dense and fine micro-structured lead zirconate titanate (PZT) fibers were successfully fabricated by sol-gel process from lead acetate dehydrate, zirconium normal butoxide, and titanium isopropoxide. An addition of perovskite seed particles (2 wt%) can lower the formation temperature of the perovskite phase and a single-phase perovskite PZT fiber can be obtained by heat-treating the precursor fiber at 500°C. Crystallization of perovskite phase was improved with the seed content. The diffraction peaks of (200) and (002) in the PZT fiber with 6 wt% seed was better split than in the PZT fiber without seed, which indicates that the tetragonality of PZT fiber was increased by adding seed particles. Seed particles also affected microstructure development of the PZT fibers. 相似文献
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Jun-ichi Ozaki Shin-ichi Tanifuji Atsuya Furuichi Katsutoshi Yabutsuka 《Electrochimica acta》2010,55(6):1864-1871
Nanoshell carbon is a type of catalytically grown nanocarbon with a hollow, round, shell-like structure, with a diameter in the range of approximately 20-50 nm. It has been shown to possess the electrocatalytic activity for oxygen reduction reaction (ORR) and is also expected to be a non-Pt catalyst for polymer electrolyte fuel cells. This paper reports the synergetic enhancement of the ORR activity of nanoshell carbons caused by the coexistence of nitrogen atoms. The nanoshell carbons were prepared by the carbonization of furan resin in the presence of acetylacetonates (AAs) and of phthalocyanines (Pcs), which contained Fe, Co, and Ni. The Pc-derived nanoshells (MP-T series; M = Co or Fe, T = carbonization temperature) showed higher ORR activities than the AA-derived nanoshells (MA-T series; M = Co or Fe, T = carbonization temperature) when the same metal elements were employed. An XPS study revealed that nitrogen species were introduced to the surface of the nanoshells when Pcs were used as the nanoshell-forming catalysts, and that no metal species remained on the nanoshells. Principally, the ORR activity of the carbons was governed by the presence of the nanoshells and further enhancement could be achieved by the introduction of nitrogen atoms. 0.78 V of OCV and 0.21 W cm−2 of the maximum power density were observed for a fuel cell whose MEA consisted of 3CoP1000 cathode and a commercial Pt/C anode, when it was operated at 80 °C under a pressurized condition of 0.35 MPa. 相似文献
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Ifeanyi A. Anyanwu Yasuhiro Gokan Atsuya Suzuki Shigeharu Kamado Yo Kojima Suguru Takeda Taketoshi Ishida 《Materials Science and Engineering: A》2004,380(1-2):93-99
Mg–Zn–Al–Ca–RE alloys have been found to be promising materials for substituting aluminum alloys used for automatic transmission case applications in the automobile industry. Particularly, Mg–0.5%Zn–6%Al–1%Ca–3%RE (ZAXE05613) alloy exhibits comparable creep resistance as ADC12 die-casting aluminum alloy that is currently used for automatic transmission case applications. Changing the rare earth (RE) content of the alloy from mischmetal to lanthanum gives a further improvement in the creep properties of the alloy. Lanthanum addition results in the crystallization of a large amount of acicular Al11RE3 (Al11La3) compound along the grain boundaries as well as across the grain boundaries and this effectively controls grain boundary sliding and dislocation motion in the vicinity of the grain boundaries. As a result, die-cast ZAXLa05613 alloy exhibits a higher creep resistance than that of ZAXE05613 alloy. 相似文献
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Atsuya Matsui Jean-Pierre Bellier Takeshi Kanai Hiroki Satooka Akio Nakanishi Tsukasa Terada Takafumi Ishibe Yoshiaki Nakamura Hiroyasu Taguchi Nobuyasu Naruse Yutaka Mera 《International journal of molecular sciences》2022,23(2)
The most common type of dementia, Alzheimer’s disease, is associated with senile plaques formed by the filamentous aggregation of hydrophobic amyloid-β (Aβ) in the brains of patients. Small oligomeric assemblies also occur and drugs and chemical compounds that can interact with such assemblies have attracted much attention. However, these compounds need to be solubilized in appropriate solvents, such as ethanol, which may also destabilize their protein structures. As the impact of ethanol on oligomeric Aβ assembly is unknown, we investigated the effect of various concentrations of ethanol (0 to 7.2 M) on Aβ pentameric assemblies (Aβp) by combining blue native-PAGE (BN-PAGE) and ambient air atomic force microscopy (AFM). This approach was proven to be very convenient and reliable for the quantitative analysis of Aβ assembly. The Gaussian analysis of the height histogram obtained from the AFM images was correlated with band intensity on BN-PAGE for the quantitative estimation of Aβp. Our observations indicated up to 1.4 M (8.3%) of added ethanol can be used as a solvent/vehicle without quantitatively affecting Aβ pentamer stability. Higher concentration induced significant destabilization of Aβp and eventually resulted in the complete disassembly of Aβp. 相似文献
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Atsuya Towata Hae Jin Hwang Masaki Yasuoka Mutsuo Sando Koichi Niihara 《Journal of the American Ceramic Society》1998,81(9):2469-2472
This paper involves novel fabrication processes for polycrystalline α-Al2 O3 -matrix composite fibers that contain nanosized yttrium aluminum garnet (YAG) particles. Dense α-Al2 O3 /YAG nanocomposite fibers with a fine and homogeneous microstructure can be successfully fabricated via a modified sol-gel process and α-Al2 O3 seed-particle addition. YAG nanoparticles have been homogeneously dispersed within Al2 O3 -matrix grains as well as at grain boundaries. Effects of α-Al2 O3 seed particles and YAG nanodispersions on crystallization and microstructure development of nanocomposite fibers are discussed. 相似文献
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Magnesium borohydride (Mg(BH4)2) is a promising material for hydrogen storage because of its high gravimetric storage density (15.0 mass%). We intended to synthesize Mg(BH4)2 by decomposition reaction of LiBH4 with MgCl2 by heat treatment without using a solvent, where the product consists of LiCl and a compound of magnesium, boron and hydrogen. Hydrogen desorption temperature of the product is approximately 100 K lower than that of LiBH4 and the decomposition consists of a two-step reaction. The products of the 1st and 2nd decomposition reactions are MgH2 and Mg, respectively. This result indicates the following two-step reaction (1st reaction: Mg(BH4)2→MgH2+2B+3H2, 2nd reaction: MgH2→Mg+H2). The first decomposition peak is dominant and is around 563 K. The 2nd decomposition occurs at the temperature greater than 590 K. 相似文献
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We study bifurcations of invariant graphs in skew-product dynamical systems driven by hyperbolic surface maps T like Anosov surface diffeomorphisms or baker maps and with one-dimensional concave fibre maps under multiplicative forcing when the forcing is scaled by a parameter r = e ?t . For a range of parameters two invariant graphs (a trivial and a non-trivial one) coexist, and we use thermodynamic formalism to characterize the parameter dependence of the Hausdorff and packing dimension of the set of points where both graphs coincide. As a corollary we characterize the parameter dependence of the dimension of the global attractor : Hausdorff and packing dimension have a common value , and there is a critical parameter γ? c determined by the SRB measure of T ?1 such that for t?γ? c and is strictly decreasing for t∈[γ? c , γmax ). 相似文献