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Kawasaki, Japan

Tsuruoka S.,Shinshu University | Matsumoto H.,Tokyo Institute of Technology | Koyama K.,Shinshu University | Akiba E.,Kuraray Living Co. | And 9 more authors.
Carbon | Year: 2015

Progress in the development of carbon nanotubes (CNTs) has stimulated great interest among industries providing new applications. Meanwhile, toxicological evaluations on nanomaterials are advancing leading to a predictive exposure limit for CNTs, which implies the possibility of designing safer CNTs. To pursue safety by design, the redox potential in reactions with CNTs has been contemplated recently. However, the chemical reactivity of CNTs has not been explored kinetically, so that there is no scheme to express a redox reaction with CNTs, though it has been investigated and reported. In addition, the reactivity of CNTs is discussed with regard to impurities that consist of transition metals in CNTs, which obfuscates the contribution of CNTs to the reaction. The present work aimed at modeling CNT scavenging in aqueous solution using a kinetic approach and a simple first-order reaction scheme. The results show that CNTs follow the redox reaction assumption in a simple chemical system. As a result, the reaction with multiwalled CNTs is semiquantitatively denoted as redox potential, which suggests that their biological reactions may also be evaluated using a redox potential scheme. © 2014 Elsevier Ltd. All rights reserved. Source

Yokozeki T.,University of Tokyo | Ishibashi M.,GSI Creos Corporation | Kobayashi Y.,University of Tokyo | Shamoto H.,Laserx Co. | Iwahori Y.,Japan Aerospace Exploration Agency
Advanced Composite Materials | Year: 2015

Pulsed laser surface treatment was applied to carbon fiber-reinforced plastics (CFRPs) to enhance the work efficiency as well as to establish the stable clean process of surface pre-treatment during the bonding process of CFRP structures. Surface analyses were conducted to CFRP treated by various laser conditions in order to find the optimal laser process. Adhesively bonded specimens were fabricated using CFRPs subjected to laser treatment, and adhesive lap shear strength of CFRPs bonded with adhesive films was evaluated compared with the abrasive paper treatment. Surface conditions, adhesive strength, and adhesive fracture mode depended on the treatment parameters, and adhesive strength similar to abrasive paper treatment could be obtained in the specimens with appropriate laser treatment. It was concluded that laser surface treatment can be applied to the surface treatment process of CFRP bonded structures. © 2015 Japan Society for Composite Materials, Korean Society for Composite Materials and Taylor & Francis Source

Tsuruoka S.,Shinshu University | Matsumoto H.,Tokyo Institute of Technology | Castranova V.,West Virginia University | Porter D.W.,U.S. National Institute for Occupational Safety and Health | And 4 more authors.
Carbon | Year: 2015

The present study systematically examined the kinetics of a hydroxyl radical scavenging reaction of various carbon nanotubes (CNTs) including double-walled and multi-walled carbon nanotubes (DWCNTs and MWCNTs), and carbon nano peapods (AuCl3@DWCNT). The theoretical model that we recently proposed based on the redox potential of CNTs was used to analyze the experimental results. The reaction kinetics for DWCNTs and thin MWCNTs agreed well with the theoretical model and was consistent with each other. On the other hand, thin and thick MWCNTs behaved differently, which was consistent with the theory. Additionally, surface morphology of CNTs substantially influenced the reaction kinetics, while the doped particles in the center hollow parts of CNTs (AuCl3@DWCNT) shifted the redox potential in a different direction. These findings make it possible to predict the chemical and biological reactivity of CNTs based on the structural and chemical nature and their influence on the redox potential. © 2015 Elsevier Ltd. Source

Hirano Y.,Japan Aerospace Exploration Agency | Yokozeki T.,University of Tokyo | Ishida Y.,Japan Aerospace Exploration Agency | Goto T.,Yamagata University | And 5 more authors.
Composites Science and Technology | Year: 2016

In this paper, the effectiveness of lightning damage suppression by a carbon-fiber-reinforced polymer (CFRP) laminate with a newly developed polyaniline (PANI)-based conductive thermosetting resin was experimentally examined by conducting simulated lightning and residual strength tests. We developed the PANI-based conductive thermosetting resin using dodecylbenzenesulfonic acid (DBSA) and p-toluenesulfonic acid (PTSA) as dopants and divinylbenzene (DVB) as a crosslinking agent, which improved the electrical conductivity and homogeneity of the resin. The electrical conductivity values for the PANI-based composite were 148 and 0.73 S/cm in the in-plane and out-of-plane directions, which are 5.92 times and 27.4 times greater than that of a conventional carbon fiber (CF)/epoxy composite, respectively. As a result, the PANI-based composite, when subjected to simulated lightning currents of -40 and -100 kA, showed dramatic improvements in lightning damage resistance compared to the conventional CF/epoxy composite. The residual strength examined by 4-point flexural testing after the simulated lightning test at -100 kA revealed only a 10% reduction from its initial strength, whereas the damaged CF/epoxy specimen tested at -40 kA showed a 76% reduction. Thus, the superior electrical conductivity of the CF/PANI composite quite effectively suppressed lightning damage without applying any lightning strike protection (LSP). © 2016 Elsevier Ltd. Source

GSI Creos Corporation | Date: 2003-12-16

Toys, namely, plastic scale model vehicle kits, [ jigsaw, manipulative and cube type puzzles, dolls ].

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