Browsing by Author "Kobayashi, H."

Now showing 1 - 3 of 3

The 3D atomic scale and electronic structure characterization of novel fcc ruthenium nanoparticles using synchrotron light source
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Kumara, L.S.R.; Sakata, O.; Kohara, S.; Song, C.; Yang, A.; Kusada, K.; Kobayashi, H.; Kitagawa, H.
Ruthenium (Ru) is a 4d transition metal that in the bulk adopts hexagonal closepacked (hcp) structure at all temperature ranges, and novel face-centered cubic (fcc) Ru nanoparticles (NPs) have been observed to be more efficient than conventional hcp Ru NPs larger than 3 nm. It has recently attracted much attention as a potential application in removal of car exhausts due to high catalytic activity for CO oxidation and preventing CO poisoning in fuel-cell system. We here report the 3-dimentational atomic-scale structures of fcc and hcp Ru NPs using high-energy X-ray diffraction (HEXRD), Rietveld analysis, pair distribution function (PDF), and reverse Monte Carlo (RMC) modelling. Hard X-ray photoelectron spectroscopy (HAXPES) can provide important information on the influence of NP size on electronic properties. The HEXRD and HAXPES of Ru NPs were performed at BL04B2 and BL15XU at SPring-8, the world largest third-generation (8 GeV) synchrotron radiation facility located in Hyōgo prefecture, Japan. We observed higher stability of the lattice distortion of fcc Ru NPs with increasing particle size. The PDF analysis results show that the structural disordered Ru NPs at short- to intermediate-range atomic distances. The order parameter for fcc Ru NPs decreased with increasing particle size due to the loosely packing atomic arrangement and may explain an origin of higher catalytic activity of fcc Ru NPs. In this study, the observed trend of increasing catalytic activity of fcc Ru NPs was also discussed using their core-levels and valence band electronic structures. This work was partly supported by ACCEL, Japan Science and Technology Agency (JST) and also partly supported by Ministry of Education, Culture, Sports, Science and Technology of Japan (OS: 15K04616).
Correlation between the Izumiyama porcelain ceramics and the red-overglaze enamels of the Kakiemon-style porcelains
(Ceramics International, 2008) Kajihara, S.; Hidaka, M.; Wijesundera, R.P.; Kumara, L.S.R.; Kobayashi, H.; Koga, M.; Tsuru, T.; Koga, K.; Shimomura, K.; Choi Jae-Young; Sung, N.E.; Park, Y.J.
The Kakiemon-style porcelains made from 17th century at Arita are famous Japanese porcelains, characterized mainly by their colored underglaze and overglaze and by their original design of coloring spatial patterns in the porcelain surface. Raw materials of the red-overglaze enamels have been investigated by means of X-ray diffraction and X-ray absorption spectra using synchrotron radiations. It is found that Izumiyama porcelain ceramics of yellow color can produce the Kakiemon red-overglaze enamels by thermal treatment and water-washing, where Izumiyama is a collecting place of the raw porcelain ceramic at Arita. The brightness of the red-overglaze enamels is related on the local structure around Fe ions and the electronic band states of Fe ions near a Fermi level in ?-Fe2O3, in addition to the spatial density of the ?-Fe2O3 fine particles. The structural and electronic properties are slightly affected by an electron-hybridization between Fe ions of ?-Fe2O3 and oxygen ions of the (SiO2?Al2O3) complexes in the red overglaze.
Developing and Strengthening Farmer-Agribusiness Models in Sri Lanka: Lessons from Agriculture Cooperatives in Japan
(2011) Esham, M.; Kobayashi, H.; Matsumura, I.; Alam, A.
In a small farmer dominated agrarian economy like Sri Lanka, farmer based organizations (FBOs) and collective action are often seen as key factors in enhancing farmers? access to markets. Therefore, developing and strengthening FBOs consisting of farmer companies and farmer organization are important to ensure effective farmer participation in agrifood supply chains. In this paper, an attempt is made to draw from long accumulated experiences of Japanese agriculture cooperatives to develop and strengthen FBOs in Sri Lanka. Some key recommendations for FBOs in Sri Lanka arising from this study include setting up of federated structures, formation of farmer groups to capitalize on collective action, practice joint use in terms of purchasing, marketing, credit, machinery and facilities use and adoption of an integrated service provision model.