Anode performance control of micro-tubular SOFC via wet coating method

A cathode-supported micro SOFC was prepared via co-sintering technique of a scandia-stabilized zirconia (ScSZ) electrolyte layer and a micro-tubular (La,Sr)_xMnO_3−δ (LSM) support, and subsequent deposition of various anode layers by dip-coating method. The micro-tubular SOFCs were electrochemically evaluated in a humidified H₂ (3% H₂O) atmosphere. An LSM-Ce_0.9Gd_0.1O_1.95 activation layer was also introduced between the cathode tube and the electrolyte layer in order to improve the catalytic activation at the cathode side. The micro SOFCs exhibited a stable open circuit voltage above 1.05 V at 650 °C, and the cells with the anode film thicknesses of 8, 30 and 50 μm generated a maximum power density of 36, 49 and 126 mW/cm², respectively. And, the cell with 50 μm thick anode layer showed about 10 times higher exchange current density than the others, which indicates that the anode performance on the cathode-supported micro SOFC was greatly affected by the thickness of the anode coating layer.     

Effect of intercalated aromatic sulfonates on uptake of aromatic compounds from aqueous solutions by modified Mg-Al layered double hydroxide

In this study, we utilized Mg-Al layered double hydroxide (Mg-Al LDH) modified by intercalation with three aromatic sulfonates—2,7-naphthalene disulfonate (2,7-NDS²⁻), benzenesulfonate (BS⁻), and benzenedisulfonate (BDS²⁻)—for the uptake of two aromatics—1,3-dinitrobenzene (DNB) and anisole (AS)—from aqueous solution and determined the effect of the aromatic sulfonates on the uptake of these aromatics. We found that the electron-rich aromatic ring of the intercalated aromatic sulfonates such as 2,7-NDS²⁻ undergoes strong π-π stacking interactions with the electron-poorer benzene ring of DNB in aqueous solution, and these interactions result in a higher uptake of DNB by the modified Mg-Al LDHs. In contrast, the electron-poor aromatic ring of the aromatic sulfonates such as BDS²⁻ undergoes weak π-π stacking interactions with the electron-poorer benzene ring of DNB, and these interactions result in a lower uptake of DNB by the modified Mg-Al LDHs.     

The effect of nonequilibrium condensation on hysteresis phenomenon of under-expanded jets

Under-expanded jets which are discharged from an orifice or a nozzle have long been subject of researches for aeronautical and mechanical applications. Provided that the jet pressure ratio and nozzle configuration are known, the major features of the steady jet are now well known. However, the jet pressure ratio is often varied even during the process in many practical applications. Many questions remain unanswered with regard to how the supersonic jet responds to the transient process of the pressure ratio and whether the steady jet data for a specific pressure ratio can still bear the same during the transient process of pressure ratio. In the present study, the hysteric phenomenon of under-expanded jets has been investigated with the help of computational fluid dynamics methods. The under-expanded jets of both dry and moist air have been employed to investigate the transient processes of the pressure ratio. The effects of nonequilibrium condensation occurring in the under-expanded moist air jets are explored on the hysteresis phenomenon. It is known that under-expanded air jet produced during the startup transient of jet behaves differently from the shutdown transient process, leading to the hysteric phenomenon of under-expanded jet. It is also known that the moist air jet reduces the hysteric phenomenon, compared with the dry air jet, and that non-equilibrium condensation which occurs in the underexpanded moist air jet is responsible for these findings. This paper was recommended for publication in revised form by Associate Editor Do Hyung Lee Heuy-Dong Kim received his B.S. and M.S. degrees in Mechanical Engineering from Kyungpook National University, Korea, in 1986 and 1988, respectively. He then received his Ph.D. degree from Kyushu University, Japan, in 1991. Dr. Kim is currently a Professor at the School of Mechanical Engineering, Andong National University, Korea. His research interests include High-Speed Trains, Ramiet and Scramiet, Shock Tube and Technology, Shock Wave Dynamics, Explosions & Blast Waves, Flow Measurement, Aerodynamic Noises and Supersonic Wind Tunnels. Min-Sung Kang received his B.S. and M.S degrees in Mechanical Engineering from Andong National University, Korea, in 2007 and 2009, respectively. Mr. Kang is currently a researcher at the School of Mechanical Engineering at Andong National University, Korea. His research interests include cavity and supersonic nozzle flows. Yumiko Otobe received her B.S. degree in Faculty of Engineering from Yamaguchi University, Japan, in 1978. She then received her Eng. D. degree from Saga University, Japan, in 2007. Dr. Otobe is currently a Research Associate at the Department of Control & Information Systems Engineering, Kitakyushu National College of Technology, Japan. Dr. Otobe’s research interests include sonic and supersonic jets of various gases as well as nonequilibrium condensation phenomena. Toshiaki Setoguchi received his B.S. degree in Mechanical Engineering from Tokyo University of Agriculture and Technology, Japan, in 1976. He then received his M.S. and Ph.D. degrees from Kyushu University, Japan, in 1978 and 1981, respectively. Dr. Setoguchi is currently a Professor at the Department of Mechanical Engineering, Saga University, Japan. His research interests include Nonequilibrium Condensation, Ramiet and Scramiet, Shock Tube and Technology, Shock Wave Dynamics, Explosions & Blast Waves, Aerodynamic Noises and Turbomachinery.     

Analysis of heat-treated graphite oxide by X-ray photoelectron spectroscopy

X-ray photoelectron spectroscopy (XPS) is among the most powerful methods to determine the surface chemical properties of carbon materials. Because heat-treated graphite oxide includes various defects, analyses of the structure by XPS help us understand the structures of various carbon materials. Thus, XPS spectra of graphene-related materials containing various functional groups and other defects on edges and in the basal plane were simulated and full width at half maximums (FWHMs) and peak shifts were obtained by density functional theory calculation. Shifts of whole C1s spectra were influenced by the electron-withdrawing functional groups such as C=O-containing functional groups. FWHMs of the main peak of C1s spectra were influenced by mainly electron-withdrawing functional groups in addition to defects such as vacancy, pentagons, and heptagons. Analyses using only XPS provide us limited information, even though the peak tops and FHWMs of simulated XPS spectra are used for assignment. Combination use of peak shifts and FWHMs of XPS spectra, infrared spectroscopy, and density functional theory calculation provided more reliable assignments of defects including oxygen-containing functional groups of carbon materials than commonly used methods using only peak shifts of XPS spectra.     

A series of modeling of plasma etching and damage reduction: vertically integrated computer aided design for device processing

The present stage of a series of numerical modelings of the plasma etching processes is overviewed. Physical, chemical and electrical linkage among modules describing low-temperature plasma structure/function in a reactor, the profile and local charging evolution in a hole/ trench, and electrical device damage during etching will make it possible to preparea technology computer aided design (TCAD) for the practical purpose of prediction and design of the etching process. This system will also help us to determine device arrangement and size in the system on a chip (SoC) in a closed integration system. Vertically integrated CAD for device processing (VicAddress) has been recently proposed by the authors. VicAddress will also provide a tool for discussing the etching processes between process engineers and device designers in the age of nanometer-scale device technology.     

THERMAL STRESSES IN A NONHOMOGENEOUS THICK PLATE UNDER STEADY DISTRIBUTION OF TEMPERATURE

This paper is concerned with a method for calculating the thermal-stress distribution in a nonhomogeneous medium whose shear modulus and coefficient of thermal expansion are assumed to be functions of z. The solution of the problem is determined by using displacement functions. A solution is then derived for the thermal-stress distribution in a nonhomogeneous, thick elastic plate under steady distribution of the surface temperature. Numerical results are presented.     

Stress-Focusing Effect Following Dynamically Transforming Anisotropic Strains in a Spherical Zirconia Inclusion

When an infinite elastic medium with a spherical inclusion of zirconia is suddenly subjected to an instantaneous transversely anisotropic phase transformation caused by impact cooling, stress waves occur at the surface of spherical inclusion the moment instantaneous transformation strains are applied. The stress waves in an inclusion proceeds radially inward to the center of the inclusion and show the stress-focusing effects. This paper analyzes the stress-focusing effects caused by the transversely isotropic phase transformation in the spherical inclusion of zirconia embedded in the infinite domain. By using the ray theory, the numerical results give a clear indication of the mechanism of stress-focusing effects caused by the phase transformation.     

Counter-Rotating Type Tidal Range Power Unit

The counter-rotating type tidal range power unit composed of the axial flow type tandem runners and the peculiar generator with double rotational armatures is proposed to utilize effectively the tidal range. In the unit, the front and the rear runners counter-drive the inner and the outer armatures of the generator, respectively. Besides, the flow runs in the axial direction at the rear runner outlet while the flow has not the swirling component at the front runner inlet, because the angular momentum change through the rear runner must coincides with that through the front runner. Such operations are suitable for bidirectional flows, namely working at the seashore with the rising and the falling tidal ranges, and the unit may be able to take place of the traditional bulb type turbines. To promote more the tidal power generation by this type unit, the runners were modified so as to be suitable for both rising and falling flows. The hydraulic performances are acceptable and take the optimum efficiency at the on-cam operation, while the trailing profiles of the runner blades determine mainly the theoretical output.     

Numerical Flow Simulation in Turbine Mode of Counter-Rotating Type Pumping Unit to Cooperate with Wind Turbine

This serial research has proposed the hybrid power system combined the wind power unit with the counter-rotating type pump-turbine unit, to provide the constant output for the grid system, even at the suddenly fluctuating/turbulent wind circumstance. In this paper, the tandem impellers prepared for the counter-rotating type pumping unit were operated at the turbine mode, and the performances and the flow conditions were investigated numerically with accompanying the experimental results. Even though providing the pumping unit for the turbine mode, the maximum hydraulic efficiency is close to one of the counter-rotating type hydroelectric unit designed exclusively for the turbine mode. Besides, the runners/impellers of the unit work evidently so as to coincide the angular momentum change through the front runners/impellers with that through the rear runners/impellers, namely to take the axial flow at not only the inlet but also the outlet, without the guide vanes. From these results, it can be concluded that this type unit is effective to work at not only the pumping but also the turbine modes.     

Efficient total synthesis of novel bioactive microbial metabolites

Bioactive natural products produced by microbes have almost limitless potential in pharmaceutical applications, and the organic synthesis of such products as lead compounds will result in the creation of new and widely useful pharmaceutical products. A program of discovery of naturally occurring bioactive microbial metabolites has been ongoing at the Kitasato Institute. We have also developed efficient, rational, and highly flexible production methods for generation of target compounds, synthesis of related compounds, elucidation of their structure-activity relationships, and the possible creation of improved bioactive compounds. In this Account, the isolation and total synthesis of naturally occurring bioactive microbial metabolites in order to create novel medicines for specific illnesses is described. This covers diseases and conditions such as atherosclerosis, Alzheimer's disease, cancer, inflammation, and osteoporosis, among others, and focuses on six specific compounds. Pyripyropenes were discovered from Aspergillus fumigatus FO-1289 through our screening of microbial metabolites that strongly inhibit acyl-CoA cholesterol acyltransferase (ACAT) in order to develop a new class of cholesterol-lowering agents. These novel polyoxygenated mixed polyketide-terpenoid (meroterpenoid) metabolites contain a fused pyridyl alpha-pyrone moiety. We carried out the first total synthesis of (+)-pyripyropene A via a flexible, concise, and highly efficient route and also clarified the structure-activity relationships. Arisugacins were discovered from Penicillium sp. FO-4259 by our screening of microbial metabolites that strongly inhibit acetylcholinesterase (AChE) in order to create novel medicines for Alzheimer's disease (AD). Arisugacins are also meroterpenoids. We have achieved the first convergent total synthesis of arisugacins A and B. Lactacystin was isolated from Streptomyces sp. OM-6519 via our screening of microbial metabolites that promote the differentiation of the neuroblastoma cell to further discover new AD medicines. Lactacystin has a novel gamma-lactam thioester structure and is also a selective and strong proteasome inhibitor. We have developed a concise approach to synthesize lactacystin designed to afford easy access to the original compound and a variety of analogs. Macrosphelides were isolated from Microsphaeropsis sp. FO-5050 from our screening of microbial metabolites that inhibit the adhesion of HL-60 cells to human umbilical vein endothelial cells (HUVEC). Macrosphelides are the first 16-membered macrotriolides. Macrosphelides prevent cell-cell adhesion by inhibiting the binding of sialyl Lewis X to E-selectin. We have accomplished the first efficient total synthesis of macrosphelides. Madindolines were isolated from Streptomyces nitrosporeus K93-0711 by our program to discover new interleukin 6 (IL-6) modulators. Madindolines are comprised of a 3a-hydroxyfuroindoline ring connected at nitrogen via a methylene bridge to a cyclopentene-1,3-dione ring. We have developed an efficient and practical total synthesis of madindolines. Madindoline A binds to gp130 selectively and inhibits IL-6 activity. Neoxaline was isolated from Aspergillus japonicus Fg-551. Neoxaline is a member of a novel class of biologically active indole alkaloids characterized by a unique indoline spiroaminal framework and binds to tubulin, which results in inhibition of tubulin polymerization. We have developed a concise stereoselective synthesis of the indoline spiroaminal framework of neoxaline.