National College of Technology, Suzuka College

www.suzuka-ct.ac.jp/english/
Suzuka, Japan
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Iwata M.,National College of Technology, Suzuka College | Jami M.S.,International Islamic University Malaysia
Drying Technology | Year: 2010

This article presents an efficient approach for the analysis of combined electroosmotic dewatering (EOD) and mechanical expression (ME) using the Terzaghi-Voigt combined model by considering creep deformation of the material. The EOD-ME process enhances dewatering because it combines the advantage of electroosmosis and mechanical dewatering, resulting in reduced void ratio compared to individual operation. The basic differential equation based on the model is solved analytically by assuming that both an electroosmotic pressure gradient Epg and a modified consolidation coefficient Ce of the material are constant, resulting in the equation of solid compressive pressure in the material as a function of time and position. The analysis also leads to the equation of the average consolidation ratio Uc, which is a measure of the progress of dewatering; this equation can describe well the empirical results under various conditions. The proposed approach can clearly explain the relationship of the driving forces of individual mode of operation. The large water content of semisolid bentonite-water mixture can effectively be reduced by the EOD-ME combined operation analyzed in this research. © 2010 Taylor & Francis Group, LLC.


Islam M.Z.,University of Shizuoka | Alam J.M.,University of Shizuoka | Tamba Y.,National College of Technology, Suzuka College | Karal M.A.S.,University of Shizuoka | Yamazaki M.,University of Shizuoka
Physical Chemistry Chemical Physics | Year: 2014

We recently developed the single giant unilamellar vesicle (GUV) method for investigating the functions and dynamics of biomembranes. The single GUV method can provide detailed information on the elementary processes of physiological phenomena in biomembranes, such as their rate constants. Here we describe the process of pore formation induced by the antimicrobial peptide (AMP), magainin 2, and the pore-forming toxin (PFT), lysenin, as revealed by the single GUV method. We obtained the rate constants of several elementary steps, such as peptide/protein-induced pore formation in lipid membranes and the membrane permeation of fluorescent probes through the pores. Information on the entry of the cell-penetrating peptide (CPP), transportan 10 (TP10), into a single GUV and its induced pore formation in lipid membranes was also obtained. We compare the single GUV method with other methods for investigating the interaction of peptides/proteins with lipid membranes (i.e., the large unilamellar vesicle (LUV) suspension method, the GUV suspension method, and single channel recording), and discuss the pros and cons of the single GUV method. On the basis of these data, we discuss the advantages of the single GUV method. This journal is © the Partner Organisations 2014.


Wada N.,National College of Technology, Suzuka College | Kojima K.,Ritsumeikan University
Optical Materials | Year: 2013

In 70B2O3-30CaO-xTb2O3 glasses (x = 0.10-20.0 (mole fraction)) prepared by the melt-quenching method, the decay behavior of the green fluorescence due to the 5D4 → 7F5 transition of Tb3+ ions was investigated by measuring the fluorescence spectra and time-resolved fluorescence spectra and then by analysis using the integrated intensity ratio of fluorescence bands due to the 5D3 → 7FJ (J = 5, 4, and 3) and 5D4 → 7FJ (J = 6, 5, 4, 3, 2, 1, and 0) transitions of Tb3+ ions, and the rate equations. In a 70B2O3-30CaO glass with high phonon energy, it was found that the 98.5% of all the excited electrons of Tb3+ ions were relaxed from the 5D3 to 5D4 level due to the multiphonon relaxation (MR) process. In addition, for x > 6.0, the green fluorescence rapidly decayed with increasing x, because the cross-relaxation process, (5D4 → 7F 0) → 3(7F0 ← 7F 6) among the excited Tb3+ ion at 5D4 and its three neighboring Tb3+ ions at 7F6 easily occurred. For x = 6, the cross-relaxation process, (5D 3 → 5D4) → (7F0 ← 7F6) between Tb3+ ions was fully promoted and the cross-relaxation process, (5D4 → 7F0) → 3(7F0 ← 7F6) was repressed, and almost 100% of excited electrons in Tb3+ ions were available for the fluorescence due to the 5D4 → 7FJ transitions. As a result, it was found that the 70B2O3-30CaO-6Tb 2O3 glass had a potential of the green fiber laser. © 2012 Elsevier B.V. All rights reserved.


Manaka H.,Kagoshima University | Miura Y.,National College of Technology, Suzuka College
Journal of the Korean Physical Society | Year: 2013

We performed temperature (T) dependence experiments on the AC magnetic susceptibility of equilateral and non-equilateral triangular spin tubes CsCrF4 and α-KCrF4, respectively. In α-KCrF4, the linear (X 0′) and the nonlinear (X 2′) magnetic susceptibilities show sharp peaks at 4.0 K, which corresponds to an antiferromagnetic phase transition. On the other hand, in CsCrF4, broad and positive X 0′ (T) peaks appear above f = 31 Hz at T ≃ 4 K, but no anomaly of X 0′ (T) occurs at f = 31 Hz. Furthermore, the X 2′ (T) curve at f = 977 Hz shows a broad and negative peak at T ∼3 K. We suspect that there is a gradual change in spin dynamics below T ≃ 4 K from the paramagnetic state at a high temperature to a slowly-fluctuating spin state without typical antiferromagnetic longrange order as one-dimensionality along the spin tubes coexists with geometrical spin frustration in the equilateral triangular planes. © 2013 The Korean Physical Society.


Oono Y.,Daido University | Sounai A.,National College of Technology, Suzuka College | Hori M.,Daido University
Journal of Power Sources | Year: 2012

The mechanism underlying the decline in cell voltage over time was investigated for high-temperature proton exchange membrane fuel cells. Five identical cells were prepared and long-term power generation tests were conducted at an operation temperature of 150 °C and a current density of 0.2 A cm -2 for periods of up to 17,860 h. Each of the cells was then analyzed using transmission electron microscopy and electron probe micro-analysis (EPMA). The results indicated that growth of the Pt catalyst particles occurred during operation, in addition to oxidation of the carbon support. Degradation of the catalyst layers was investigated by EPMA of cross sections of the membrane electrode assemblies, allowing the mechanism of cell performance reduction to be clarified. © 2012 Elsevier B.V. All rights reserved.


Oono Y.,Daido University | Fukuda T.,Daido University | Sounai A.,National College of Technology, Suzuka College | Hori M.,Daido University
Journal of Power Sources | Year: 2010

The relation between high temperature proton exchange membrane fuel cell (HT-PEMFC) operation temperature and cell durability was investigated in terms of the deterioration mechanism. Long-term durability tests were conducted at operational temperatures of 150, 170, and 190 °C for a HT-PEMFC with phosphoric acid-doped polybenzimidazole electrolyte membranes. Higher cell temperatures were found to result in a higher cell voltage, but decrease cell life. The reduction in cell voltage of approximately 20 mV during the long-term tests was considered to be caused both by aggregation of the electrode catalyst particles in the early stage of power generation, in addition to the effects of crossover due to the depletion of phosphoric acid in the terminal stage, which occurs regardless of cell temperature. It is expected that enhanced long-term durability for practical applications can be achieved through effective management of phosphoric acid transfer. © 2009.


Oono Y.,Daido University | Sounai A.,National College of Technology, Suzuka College | Hori M.,Daido University
Journal of Power Sources | Year: 2013

In a previous study on the long-term operation of high-temperature proton exchange membrane fuel cells (HT-PEMFCs) with polybenzimidazole (PBI) membranes, it was found that the main cause of the observed decrease in cell voltage with time was phosphoric acid depletion due to evaporation. Based on this result, in the present study, the effects of using a different kind of cell membrane were investigated. Instead of PBI membranes, phosphoric-acid-doped, chemically cross-linked poly(2,5-benzimidazole) (ABPBI) membranes were employed in HT-PEMFCs and long-term power generation tests were carried out. Two separate cells were operated for 1000 and 17,500 h at a temperature of 150 C and a current density of 0.2 A cm-2. Their membrane electrode assemblies were then subjected to electron probe microanalysis. The results for the cell operated for 17,500 h were directly compared with those for a cell with a PBI membrane operated for 17,800 h in a previous study, allowing the mechanism of cell performance reduction in HT-PEMFCs to be further elucidated. © 2013 Elsevier B.V. All rights reserved.


Mantani Y.,National College of Technology, Suzuka College | Kudou K.,Kanagawa University
Journal of Alloys and Compounds | Year: 2013

The purpose of this study was to investigate and discuss the effect of plastic deformation on material properties, such as Young's modulus and internal friction, of the martensite structures in Ti-Nb alloys. A characteristic of the structure of Ti-10Nb alloys is the twin α structure. For Ti-15Nb alloys, it is the α′ martensite structure and for Ti-20Nb alloys, it is the α″ martensite structure. In the twin α structure, Young's modulus decreased slightly and the internal friction increased gradually with an increase in the rolling reduction rate. In the α′ martensite structure, Young's modulus decreased slightly and the internal friction decreased gradually with an increase in the rolling reduction rate. On the other hand, in the α″ martensite structure, Young's modulus decreased and the internal friction increased drastically at a weak plastic deformation. After that, Young's modulus was almost stable and the internal friction decreased with further deformation. The change in the material properties of the α′ martensite structure was considered to be caused by a decrease in the lattice constants, like a reverse transformation from α′ to α or the emission of a dislocation. The change in the material properties of the α″ martensite structure was considered to be caused by the change in the internal microstructure, such as the increase in the dislocation or twin. © 2012 Elsevier B.V. All rights reserved.


Nozaki H.,Kyushu University | Shinohara M.,National College of Technology, Suzuka College
Journal of Combinatorial Theory. Series A | Year: 2010

A subset X in the d-dimensional Euclidean space is called a k-distance set if there are exactly k distinct distances between two distinct points in X and a subset X is called a locally k-distance set if for any point x in X, there are at most k distinct distances between x and other points in X.Delsarte, Goethals, and Seidel gave the Fisher type upper bound for the cardinalities of k-distance sets on a sphere in 1977. In the same way, we are able to give the same bound for locally k-distance sets on a sphere. In the first part of this paper, we prove that if X is a locally k-distance set attaining the Fisher type upper bound, then determining a weight function w, (X,w) is a tight weighted spherical 2. k-design. This result implies that locally k-distance sets attaining the Fisher type upper bound are k-distance sets. In the second part, we give a new absolute bound for the cardinalities of k-distance sets on a sphere. This upper bound is useful for k-distance sets for which the linear programming bound is not applicable. In the third part, we discuss about locally two-distance sets in Euclidean spaces. We give an upper bound for the cardinalities of locally two-distance sets in Euclidean spaces. Moreover, we prove that the existence of a spherical two-distance set in (d-1)-space which attains the Fisher type upper bound is equivalent to the existence of a locally two-distance set but not a two-distance set in d-space with more than d(d+1)/2 points. We also classify optimal (largest possible) locally two-distance sets for dimensions less than eight. In addition, we determine the maximum cardinalities of locally two-distance sets on a sphere for dimensions less than forty. © 2009 Elsevier Inc.


Yukawa H.,Nagoya University | Nambu T.,National College of Technology, Suzuka College | Matsumoto Y.,Oita National College of Technology
Journal of Alloys and Compounds | Year: 2011

The alloying effects of tungsten on the hydrogen solubility and the hydrogen permeability are investigated for V-based hydrogen permeable membranes. The hydrogen solubility is found to decrease by the addition of tungsten into vanadium or by increasing the temperature. It is shown that the ductile fracture occurs for V-5 mol%W alloy even in the hydrogen pressures of 0.3 MPa at 773 K. It is also found that the mechanical properties (i.e., strength and ductility) of V-based alloy are better than that of Nb-based alloy in hydrogen atmosphere at high temperature. It is demonstrated that the V-5 mol%W alloy possess excellent hydrogen permeability without showing any hydrogen embrittlement when used under appropriate permeation conditions, i.e., temperature and hydrogen pressures. © 2010 Elsevier B.V. All rights reserved.

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