Kim J.D.,University of Illinois at Urbana - Champaign |
Mohseni P.K.,University of Illinois at Urbana - Champaign |
Balasundaram K.,University of Illinois at Urbana - Champaign |
Ranganathan S.,SanDisk a Western Digital Brand Milpitas 95035CA United States |
And 3 more authors.
Advanced Functional Materials | Year: 2017
Metal-assisted chemical etching (MacEtch) has shown tremendous success as an anisotropic wet etching method to produce ultrahigh aspect ratio semiconductor nanowire arrays, where a metal mesh pattern serves as the catalyst. However, producing vertical via arrays using MacEtch, which requires a pattern of discrete metal disks as the catalyst, has often been challenging because of the detouring of individual catalyst disks off the vertical path while descending, especially at submicron scales. Here, the realization of ordered, vertical, and high aspect ratio silicon via arrays by MacEtch is reported, with diameters scaled from 900 all the way down to sub-100 nm. Systematic variation of the diameter and pitch of the metal catalyst pattern and the etching solution composition allows the extraction of a physical model that, for the first time, clearly reveals the roles of the two fundamental kinetic mechanisms in MacEtch, carrier generation and mass transport. Ordered submicron diameter silicon via arrays with record aspect ratio are produced, which can directly impact the through-silicon-via technology, high density storage, photonic crystal membrane, and other related applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Toyosada K.,Fukuoka International University |
Otani T.,Fukuoka International University |
Otani T.,Kyushu University |
Shimizu Y.,Water and Lifestyle Research Laboratory |
Managi S.,Kyushu University
Water (Switzerland) | Year: 2017
This study was conducted as part of the Joint Crediting Mechanism (JCM) of the Japanese Ministry of Economy, Trade and Industry, and the Ministry of the Environment project's preparation in Vietnam. Samples were taken from hot and cold water supplies from guest rooms' faucets in 12 hotels in Hanoi city, Vietnam, and 13 hotels in Japan for comparison. A simple water quality measurement and determination of Legionella was carried out. The results showed that residual effective chlorine-which guarantees bactericidal properties-was not detected in tap water supplied in hotel rooms in Vietnam, and nitrite (an indicator of water pollution) was detected in 40% of buildings. In the hotels in Japan, the prescribed residual chlorine concentration met the prescribed levels, and nitrite was not detected. Additionally, while there was no Legionella detected in the Japanese cases, it was detected in most of the Vietnamese hotels, which were found to manage the hot water storage tank at low temperatures of 40-50 °C. It was found that there were deficiencies in cold and hot water supply quality, and that there was no effective system in place for building operation maintenance and management. © 2017 by the authors.
Mufundirwa A.,Kyushu University |
Harrington G.F.,Kyushu University |
Harrington G.F.,Massachusetts Institute of Technology |
Smid B.,Kyushu University |
And 5 more authors.
Journal of Power Sources | Year: 2017
Due to the high cost and limited availability of platinum, the development of non-platinum-group metals (non-PGM) catalysts is of paramount importance. A promising alternative to Pt are Fe-N-C-based materials. Here we present the synthesis, characterization and electrochemistry of a template-free nitrogen-doped carbon foam, impregnated with iron. This low-cost and gram-scale method results in materials with micron-scale pore size and large surface area (1600 m2g-1). When applied as an oxygen reduction reaction (ORR) electrocatalyst in alkaline solution, the Fe-N-C foams display extremely high initial activity, slightly out-performing commercially available non-PGM catalysts (NCP-2000, Pajarito Powder). The load-cycle durability in alkaline solution is investigated, and the performance steadily degrades over 60,000 potential cycles, whilst the commercial catalyst is remarkably stable. The post-operation catalyst microstructure is elucidated by transmission electron microscopy (TEM), to provide insight into the degradation processes. The resulting images suggest that potential cycling leads to leaching of atomically dispersed Fe-N2/4 sites in all the catalysts, whereas encapsulated iron nanoparticles are protected. © 2017 Elsevier B.V.
Itoh T.,Japan National Institute of Advanced Industrial Science and Technology |
Hoshikawa Y.,Tohoku University |
Matsuura S.-I.,Japan National Institute of Advanced Industrial Science and Technology |
Mizuguchi J.,Japan National Institute of Advanced Industrial Science and Technology |
And 6 more authors.
Biochemical Engineering Journal | Year: 2012
A new enzymatic process for production of l-theanine was presented using glutaminase combined with immobilization technique on carbon-coated mesoporous silica (carbon/SBA-15). For the attempt to enhance the durability against high pH conditions, the pore surface of mesoporous silica SBA-15 was coated with a thin layer of carbon. Carbon coating was done by addition of 2,3-dihydroxynaphthalene (DN) on the pore surface, followed by a dehydration reaction between surface silanol groups in SBA-15 and hydroxyl groups of DN molecules, and further carbonization of DN. A glutaminase was confined in nanospace (about 5. nm) of carbon/SBA-15. The resulting product, glutaminase/carbon/SBA-15, successfully catalyzed the reaction for production of l-theanine under high pH conditions. © 2012 Elsevier B.V.
Knauth P.,Aix - Marseille University |
Harrington G.F.,Fukuoka Institute of Technology |
Bishop S.R.,Fukuoka International University |
Saltsburg H.,Massachusetts Institute of Technology |
Tuller H.L.,Fukuoka International University
Journal of the American Ceramic Society | Year: 2016
The electrical and dilatometric properties of CeO2 nanopowders were examined as function of particle shape and size, including nanorods and nanocubes. Nanorods show continuous irreversible shrinkage, linked to particle reordering and compaction. Thermal expansion of CeO2 nanocubes was analyzed and was found to be consistent with literature data for microcrystalline ceria with no apparent nanosize effects. The electrical properties of the loosely compacted nanopowders were generally found to be characterized by n-type electronic conduction, except for proton conductivity contributions associated with adsorbed moisture at temperatures below 400°C. The PO2 and temperature dependences of the conductivity were examined in terms of defect chemical models. The lower effective enthalpy of reduction for nanorods (1.5 eV) in comparison with nanocubes (1.8 eV), both being much smaller than the value found for "bulk" ceria (4.7 eV), can be related to the larger surface to volume ratio of the nanorods, where oxide ion removal is more facile and less energy costly. © 2016 American Ceramic Society.
Shikata N.,Kyushu University |
Shikata N.,Ajinomoto Co. |
Maki Y.,Fukuoka International University |
Nakatsui M.,Kyushu University |
And 6 more authors.
Amino Acids | Year: 2010
The changes in the concentrations of plasma amino acids do not always follow the flow-based metabolic pathway network. We have previously shown that there is a control-based network structure among plasma amino acids besides the metabolic pathway map. Based on this network structure, in this study, we performed dynamic analysis using time-course data of the plasma samples of rats fed single essential amino acid deficient diet. Using S-system model (conceptual mathematical model represented by power-law formalism), we inferred the dynamic network structure which reproduces the actual time-courses within the error allowance of 13.17%. By performing sensitivity analysis, three of the most dominant relations in this network were selected; the control paths from leucine to valine, from methionine to threonine, and from leucine to isoleucine. This result is in good agreement with the biological knowledge regarding branched-chain amino acids, and suggests the biological importance of the effect from methionine to threonine. © 2009 Springer-Verlag.
Kikuchi Y.,University of Tokyo |
Kikuchi Y.,Fukuoka International University |
Kimura S.,Fukuoka International University |
Okamoto Y.,Kyushu University |
And 2 more authors.
Applied Energy | Year: 2014
The design of energy systems has become an issue all over the world. A single optimal system cannot be suggested because the availability of infrastructure and resources and the acceptability of the system should be discussed locally, involving all related stakeholders in the energy system. In particular, researchers and engineers of technologies related to energy systems should be able to perform the forecasting and roadmapping of future energy systems and indicate quantitative results of scenario analyses. We report an energy flow model developed for analysing scenarios of future Japanese energy systems implementing a variety of feasible technology options. The model was modularized and represented as functionals of appropriate technology options, which enables the aggregation and disaggregation of energy systems by defining functionals for single technologies, packages integrating multi-technologies, and mini-systems such as regions implementing industrial symbiosis. Based on the model, the combinations of technologies on both energy supply and demand sides can be addressed considering not only the societal scenarios such as resource prices, economic growth and population change but also the technical scenarios including the development and penetration of energy-related technologies such as distributed solid oxide fuel cells in residential sectors and new-generation vehicles, and the replacement and shift of current technologies such as heat pumps for air conditioning and centralized power generation. The developed model consists of two main modules; namely, a power generation dispatching module for the Japanese electricity grid and a demand-side energy flow module based on a sectorial energy balance table. Both modules are divided and implemented as submodules represented as functionals of supply- and demand-side technology options. Using the developed model, three case studies were performed. Required data were collected through workshops involving researchers and engineers in the energy technology field in Japan. The functionals of technologies were defined on the basis of the availability of data and understanding of the current and future energy systems. Through case studies, it was demonstrated that the potential of energy technologies can be analysed by the developed model considering the mutual relationships of technologies. The contribution of technologies to, e.g., the reduction in greenhouse gas emissions should be carefully examined by quantitative analyses of interdependencies of the technology options. © 2014 Elsevier Ltd. All rights reserved.
Matsunaga H.,Fukuoka International University |
Sun C.,CAS Institute of Mechanics |
Hong Y.,CAS Institute of Mechanics |
Murakami Y.,Kyushu University
Fatigue and Fracture of Engineering Materials and Structures | Year: 2015
Dominant factors affecting fatigue failure from non-metallic inclusions in the very-high-cycle fatigue (VHCF) regime are reviewed, and the mechanism for the disappearance of the conventional fatigue limit is discussed. Specifically, this paper focuses on the following: (i) the crucial role of internal hydrogen trapped by non-metallic inclusions for the growth of the optically dark area (around the non-metallic inclusion at fracture origin), (ii) the behaviour of the crack growth from a non-metallic inclusion as a small crack and (iii) the statistical aspects of the VHCF strength, in consideration of the maximum inclusion size, using statistics of extremes. In addition, on the basis of the aforementioned findings, a new fatigue design method is proposed for the VHCF regime. The design method gives the allowable stress, σallowable, for a determined design life, NfD, as the lower bound of scatter of fatigue strength, which depends on the amount of components produced. © 2015 Wiley Publishing Ltd.
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