Ono Y.,Kanagawa Industrial Technology Center
Materials Research Bulletin | Year: 2016
Crystalline meso-/macroporous TiO2 aggregate was synthesized by using a hydroxyapatite template. The hydroxyapatite could be removed by treating it with hydrochloric acid even after it was heated at 800 °C. The aggregate included macropore with sizes of 1-5 μm in diameter and longer than 5 μm in length, penetrating into the aggregate, with walls that consisted of nanoparticles. Based on the results of N2-BET and X-ray diffraction measurements, decline in specific surface area and anatase-rutile phase transformation during heating were suppressed by the addition of the hydroxyapatite. That is, the aggregate had higher specific surface area and higher anatase phase ratio than the control sample obtained without using the hydroxyapatite. Photocatalytic activity evaluated by a photo-decomposition of methylene blue dye increased with increasing heating temperature. The aggregate heat-treated at 800 °C had three times higher photocatalytic activity and twenty times larger aggregate diameter than the commercial ST-01 TiO2 powder. © 2016 Elsevier Ltd. All rights reserved.
Noguchi T.,Nagoya University |
Noguchi T.,University of Tsukuba |
Suzuki H.,University of Tsukuba |
Tsuno M.,Nagoya University |
And 4 more authors.
Biochemistry | Year: 2012
Photosynthetic oxygen evolution by plants and cyanobacteria is performed by water oxidation at the Mn 4CaO 5 cluster in photosystem II. The reaction is known to proceed via a light-driven cycle of five intermediates called S i states (i = 0-4). However, the detailed reaction processes during the intermediate transitions remain unresolved. In this study, we have directly detected the proton and protein dynamics during the oxygen-evolving reactions using time-resolved infrared spectroscopy. The time courses of the absorption changes at 1400 and 2500 cm -1, which represent the reactions and/or interaction changes of carboxylate groups and the changes in proton polarizability of strong hydrogen bonds, respectively, were monitored upon flash illumination. The results provided experimental evidence that during the S 3 → S 0 transition, drastic proton rearrangement, most likely reflecting the release of a proton from the catalytic site, takes place to form a transient state before the oxidation of the Mn 4CaO 5 cluster that leads to O 2 formation. Early proton movement was also detected during the S 2 → S 3 transition. These observations reveal the common mechanism in which proton release facilitates the transfer of an electron from the Mn 4CaO 5 cluster in the S 2 and S 3 states that already accumulate oxidizing equivalents. In addition, relatively slow rearrangement of carboxylate groups was detected in the S 0 → S 1 transition, which could contribute to the stabilization of the S 1 state. This study demonstrates that time-resolved infrared detection is a powerful method for elucidating the detailed molecular mechanism of photosynthetic oxygen evolution by pursuing the reactions of substrate and amino acid residues during the S-state transitions. © 2012 American Chemical Society.
Nakagomi S.,Ishinomaki Senshu University |
Kaneko S.,Kanagawa Industrial Technology Center |
Kokubun Y.,Ishinomaki Senshu University
Physica Status Solidi (B) Basic Research | Year: 2015
We have used X-ray pole figure analyses to study crystal orientations of β-Ga2O3 thin films formed on (100) m-plane or (102) r-plane sapphire substrates prepared by gallium evaporation in oxygen plasma. The (-201) plane of β-Ga2O3 on the (100) m-plane was inclined to be along two (110) a-planes. Crystals of (-201)-oriented β-Ga2O3 exhibit six-fold symmetry in which a β-Ga2O3 crystal is rotated every 60° from  for each a-plane. In all, twelve kinds of β-Ga2O3 crystals formed on m-plane sapphire substrate. Similarly, the (-201) plane of β-Ga2O3 on the (102) r-plane was inclined to be along to two (113) n-plane. Crystals of (-201)-oriented β-Ga2O3 exhibit three-fold symmetry with a β-Ga2O3 crystal rotated every 120° from the opposite direction of projection of the c-axis of each n-plane. In all, six kinds of β-Ga2O3 crystals formed on the r-plane sapphire substrate. These observations can be explained by comparing oxygen atomic arrangements on the β-Ga2O3 (-201) plane with those on the sapphire (110) a-plane and (113) n-plane. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Itoh Y.,Kanagawa Industrial Technology Center
Nihon Kikai Gakkai Ronbunshu, C Hen/Transactions of the Japan Society of Mechanical Engineers, Part C | Year: 2013
The main purpose of the current study is to model and identify vibrations in mechanical systems subject to arbitrary external excitations. In this paper, we propose a method based on infinite impulse response digital filter technology - termed time-frequency analysis - to analyze transient and steady-state vibrations. Firstly, we introduce the time-frequency analysis procedure and the algorithm to implement this procedure. Secondly, we analyze typical discrete signal inputs such as impulse, sinusoidal and swept sine signals, and present time-frequency characteristics for transient and steady-state signals. Thirdly, we apply our analysis method to the mechanical vibration behavior of a single- degree-of-freedom system subjected to various types of external excitations. The results of our analysis for steady-state vibration are verified as being equivalent to those from a fast Fourier transform (FFT) analysis. Moreover, the proposed analysis has the advantage over FFT analysis that we can also analyze transient vibration phenomena. © 2013 The Japan Society of Mechanical Engineers.
Ono Y.,Kanagawa Industrial Technology Center
Ceramics International | Year: 2015
Macroporous α-cristobalite was successfully synthesized by using a colloid-sized template of cylindrical hydroxyapatite particles that were heat-treated at 1300 °C for 1 hour. The template was easily removed by treating it with hydrochloric acid at room temperature. The macroporous structure was confirmed with a scanning electron microscope. The pore size differed depending on the location; it was mainly 100 nm to 1 μm and larger than 2 μm in some locations. The specific surface area measured by the N2-BET method was 3 m2/g, which was three times larger than that of ordinary cristobalite. Moreover, the amount of methylene blue dye adsorbed was twice as large as that of ordinary cristobalite. © 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved.