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Hashimoto I.,National Institute of Technology, Toyama College | Kozono H.,Waseda University
Journal of Differential Equations | Year: 2017

We consider the large time behavior of the radially symmetric solution to the equation for a quasilinear hyperbolic model in the exterior domain of a ball in general space dimensions. In the previous paper , we proved the asymptotic stability of the stationary wave of the Burgers equations in the same exterior domain when the solution is also radially symmetric. On the other hand, in the 1D-case, a similar asymptotic structure as above to the damped wave equation with a convection term has been established by Ueda and Ueda-Kawashima Assuming a certain condition on the boundary data on the ball and the behavior at infinity of the fluid, we shall prove that the stationary wave of our quasilinear hyperbolic model is asymptotically stable. The weighted L2-energy method plays a crucial role in removing such a restriction on the sub-characteristic condition on the stationary wave. © 2017 Elsevier Inc.


Omata T.,Osaka University | Nagatani H.,Osaka University | Suzuki I.,Osaka University | Kita M.,National Institute of Technology, Toyama College | And 2 more authors.
Journal of the American Chemical Society | Year: 2014

An oxide semiconductor β-CuGaO2 with a wurtzite-derived β-NaFeO2 structure has been synthesized. Structural characterization has been carried out by Rietveld analysis using XRD and SAED, and it was shown that the lattice size is very close to that of zinc oxide. The optical absorption spectrum indicated that the band gap is 1.47 eV, which matches the band gap required to achieve the theoretical maximum conversion efficiency for a single-junction solar cell. The thermoelectromotive force indicated p-type conduction in its intrinsic state. Density functional theory calculations were performed to understand the electronic structure and optical properties of the semiconductor. These calculations indicated that β-CuGaO2 is a direct semiconductor and intense absorption of light occurs near the band edge. These properties render this new material promising as an absorber in solar cells. © 2014 American Chemical Society.


Aijaz A.,Japan National Institute of Advanced Industrial Science and Technology | Karkamkar A.,Pacific Northwest National Laboratory | Choi Y.J.,Pacific Northwest National Laboratory | Tsumori N.,National Institute of Technology, Toyama College | And 4 more authors.
Journal of the American Chemical Society | Year: 2012

Ultrafine Pt nanoparticles were successfully immobilized inside the pores of a metal-organic framework, MIL-101, without aggregation of Pt nanoparticles on the external surfaces of framework by using a "double solvents" method. TEM and electron tomographic measurements clearly demonstrated the uniform three-dimensional distribution of the ultrafine Pt NPs throughout the interior cavities of MIL-101. The resulting Pt@MIL-101 composites represent the first highly active MOF-immobilized metal nanocatalysts for catalytic reactions in all three phases: liquid-phase ammonia borane hydrolysis, solid-phase ammonia borane thermal dehydrogenation, and gas-phase CO oxidation. © 2012 American Chemical Society.


Jiang H.-L.,Japan National Institute of Advanced Industrial Science and Technology | Tsumori N.,Japan National Institute of Advanced Industrial Science and Technology | Tsumori N.,National Institute of Technology, Toyama College | Xu Q.,Japan National Institute of Advanced Industrial Science and Technology
Inorganic Chemistry | Year: 2010

A series of microporous lanthanide-organic framework enantiomers, Ln(BTC)(H 2O)•(DMF) 1.1 (Ln = Y 1a, 1b; Tb 2a, 2b; Dy 3a, 3b; Er 4a, 4b; Yb 5a, 5b, BTC = 1,3,5-benzenetricarboxylate; DMF = N,N-dimethylformamide) with unprecedented (6,6)-connected topology have been prepared and characterized. All these compounds exhibit very high thermal stability of over 450 °C. The pore characteristics and gas sorption properties of these compounds were investigated at cryogenic temperatures by experimentally measuring nitrogen, argon, and hydrogen adsorption/desorption isotherms. The studies show that all these compounds are highly porous with surface areas of 1080 (1), 786 (2), 757 (3), 676 (4), and 774 m 2/g (5). The amounts of the hydrogen uptakes, 1.79 (1), 1.45 (2), 1.40 (3), 1.51 (4), and 1.41 wt % (5) at 77 K (1 atm), show their promising H 2 storage performances. These porous materials with considerable surface areas, high voids of 44.5% (1), 44.8% (2), 47.7% (3), 44.2% (4), and 45.7% (5), free windows of 6-7 Å, available exposed metal sites and very high thermal stability can be easily prepared on a large scale, which make them excellent candidates in many functional applications, such as, gas storage, catalysis, and so on. © 2010 American Chemical Society.


Zhu Q.-L.,Japan National Institute of Advanced Industrial Science and Technology | Tsumori N.,Japan National Institute of Advanced Industrial Science and Technology | Tsumori N.,National Institute of Technology, Toyama College | Xu Q.,Japan National Institute of Advanced Industrial Science and Technology
Chemical Science | Year: 2013

Highly dispersed Pd nanoparticles (NPs) deposited on nanoporous carbon MSC-30 have been successfully prepared with a sodium hydroxide-assisted reduction approach. The modification by NaOH during the formation and growth of particles results in the well-dispersed ultrafine Pd NPs on carbon. The combination of distinct interaction between metal and support and high dispersion of NPs drastically enhances the catalytic performance of the resulted catalyst, over which the turnover frequency (TOF) for heterogeneously catalyzed decomposition of formic acid (FA) reaches 2623 h-1 at 50 °C with 100% H2 selectivity, the highest value ever reported under ambient conditions, comparable to those acquired from the most active homogeneous catalysts. Even at 25 °C, the complete dehydrogenation of FA with a TOF as high as 750 h-1 can be achieved. © 2013 The Royal Society of Chemistry.


Chen Y.,Japan National Institute of Advanced Industrial Science and Technology | Zhu Q.-L.,Japan National Institute of Advanced Industrial Science and Technology | Tsumori N.,Japan National Institute of Advanced Industrial Science and Technology | Tsumori N.,National Institute of Technology, Toyama College | Xu Q.,Japan National Institute of Advanced Industrial Science and Technology
Journal of the American Chemical Society | Year: 2015

In this work, we have developed a non-noble metal sacrificial approach for the first time to successfully immobilize highly dispersed AgPd nanoparticles on reduced graphene oxide (RGO). The Co3(BO3)2 co-precipitated with AgPd nanoparticles and subsequently sacrificed by acid etching effectively prevents the primary AgPd particles from aggregation. The resulted ultrafine AgPd nanoparticles exhibit the highest activity (turnover frequency, 2739 h-1 at 323 K) among all the heterogeneous catalysts for the dehydrogenation of formic acid to generate hydrogen without CO impurity. The sacrificial approach opens up a new avenue for the development of high-performance metal nanocatalysts. © 2014 American Chemical Society.


Yadav M.,Japan National Institute of Advanced Industrial Science and Technology | Singh A.K.,Japan National Institute of Advanced Industrial Science and Technology | Tsumori N.,Japan National Institute of Advanced Industrial Science and Technology | Tsumori N.,National Institute of Technology, Toyama College | Xu Q.,Japan National Institute of Advanced Industrial Science and Technology
Journal of Materials Chemistry | Year: 2012

Palladium nanoparticles (Pd NPs) encapsulated within hollow silica nanospheres (Pd@SiO 2) (20-35 nm) were synthesized using Pd(NH 3) 4Cl 2 as precursor in a polyoxyethylene- nonylphenyl ether/cyclohexane reversed micelle system followed by NaBH 4 reduction. Pd NPs supported on silica nanospheres (Pd/SiO 2) were prepared by the conventional impregnation of Pd(NH 3) 4Cl 2 precursor to silica nanospheres, which were prepared using a similar reversed micelle system without Pd precursor, followed by NaBH 4 reduction. The as-sythesized Pd@SiO 2 and Pd/SiO 2 catalysts have high catalytic activities, in comparison to Pd NPs supported on commercial silica, for the decomposition of formic acid at convenient temperature for chemical hydrogen storage. Remarkably, it has been observed that the interactions of the Pd nanoparticles with surface groups of silica supports are important for the catalytic performance. This journal is © The Royal Society of Chemistry.


Yadav M.,Japan National Institute of Advanced Industrial Science and Technology | Akita T.,Japan National Institute of Advanced Industrial Science and Technology | Tsumori N.,Japan National Institute of Advanced Industrial Science and Technology | Tsumori N.,National Institute of Technology, Toyama College | Xu Q.,Japan National Institute of Advanced Industrial Science and Technology
Journal of Materials Chemistry | Year: 2012

We report the first example of monometallic gold nanoparticles, functionalized with amine and encapsulated in silica nanospheres, as a high-performance catalyst for hydrogen generation from aqueous formic acid for chemical hydrogen storage. Remarkably, the presence of amine in the silica sphere can make the gold nanoparticles highly active although the unsupported or silica-supported gold NPs being inactive for this reaction. The strong metal-molecular support interaction (SMMSI) could be extended, as a general strategy, to the development of nanocatalysts which need necessary environments around the active sites for a variety of catalytic reactions. © 2012 The Royal Society of Chemistry.


Kitamura T.,National Institute of Technology, Toyama College
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2016

Usually, the solution of the conventional extreme learning machine, which is a type of single-hidden-layer feedforward neural networks, is not sparse. In this paper, to overcome this problem, we discuss a sparse extreme learning machine using empirical feature mapping. Here, the basis vectors of empirical feature space are the linearly independent training vectors. Then, unlike the conventional extreme learning machine, only these linearly independent training vectors become support vectors. Hence, the solution of the proposed method is sparse. Using UCI bench-mark datasets, we evaluate the effectiveness of the proposed method over the conventional methods from the standpoints of the sparsity and classification capability. © Springer International Publishing Switzerland 2016.


Aijaz A.,Japan National Institute of Advanced Industrial Science and Technology | Akita T.,Japan National Institute of Advanced Industrial Science and Technology | Tsumori N.,National Institute of Technology, Toyama College | Xu Q.,Japan National Institute of Advanced Industrial Science and Technology
Journal of the American Chemical Society | Year: 2013

For the first time, this work presents surfactant-free monometallic and bimetallic polyhedral metal nanocrystals (MNCs) immobilized to a metal-organic framework (MIL-101) by CO-directed reduction of metal precursors at the solid-gas interface. With this novel method, Pt cubes and Pd tetrahedra were formed by CO preferential bindings on their (100) and (111) facets, respectively. PtPd bimetallic nanocrystals showed metal segregation, leading to Pd-rich core and Pt-rich shell. Core-shell Pt@Pd nanocrystals were immobilized to MIL-101 by seed-mediated two-step reduction, representing the first example of core-shell MNCs formed using only gas-phase reducing agents. These MOF-supported MNCs exhibited high catalytic activities for CO oxidation. © 2013 American Chemical Society.

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