Thermal degradation of carboxylate‐based polyurethane anionomers

With the purpose of elucidating the thermal degradation process of carboxylated polyurethane anionomers (PUAs), characterization of PUAs containing potassium and magnesium salts was conducted using thermogravimetry and FTIR spectroscopy. Potassium salt in PUA induced pronounced acceleration on the thermal degradation of urethane linkage in the hard segment as well as ester and carbonate linkages in the soft segment. The absorption bands of ν(N? H), ν(C=O), δ(N? H), ν (C? N), and ν(C? O? C) in FTIR spectra of PUAs recorded as a function of increasing temperature demonstrated abrupt changes around the initial thermal decomposition temperature, making possible comprehensive studies of the thermal degradation process of PUAs. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 573–579, 2006     

A high-precision positioning servo controller based on phase/frequency detecting technique of two-phase-type PLL

This paper presents a new method proposed for high-precision positioning servomechanisms. The servo controller uses a two-phase-type phase-locked loop (PLL) to detect position tracking error and speed fluctuation with high resolution. Because the two-phase-type PLL has a wide frequency range and high noise suppression performance, we applied the new controller to high-power and high-velocity servo-spindles and achieved high control performance. The developed servo-spindles were used by a high-productivity numerically controlled gear grinding machine. Experiments of gear grinding were carried out, and the results confirmed the performance of the developed controller.     

Investigation of inorganic compounds on the surface of cathode materials using Li and O K-edge XANES

Inorganic compounds on the surfaces of the cathode materials LiNi_0.80Co_0.15Al_0.05O₂ and LiCoO₂ were studied using Li and O K-edge X-ray absorption near edge structure (XANES) measurements. Rietveld analysis revealed that the LiNi_0.80Co_0.15Al_0.05O₂ sample contained 2% Li₂CO₃, while the LiCoO₂ sample was single-phase. The Li and O K-edge XANES spectra indicated that the surface of LiCoO₂ was almost free of residual Li₂CO₃. In contrast, the presence of both residual Li₂CO₃ and an additional cubic phase were observed, respectively, on and near the surface of LiNi_0.80Co_0.15Al_0.05O₂. These results demonstrate that the XANES technique, using a combination of the total electron yield and fluorescence methods, is an effective tool for probing the surfaces of cathode materials.     

Room-temperature tensile and high-cycle-fatigue strength of fine TiB particulate-reinforced Ti-22Al-27Nb composites

To further improve the mechanical properties of a Ti-22Al-27Nb (mol pct) alloy, based on the ordered orthorhombic Ti₂AlNb (O phase), a TiB particulate-reinforced Ti-22Al-27Nb matrix composite was prepared using the gas-atomized powder metallurgy method. Because of the rapid solidification during the gas atomization process, the TiB particulates dispersed in the composite were extremely fine, with an average diameter of less than 1 μm and lengths ranging up to 5 μm. This composite (PM composite) showed higher tensile and high-cycle-fatigue properties at room temperature than both an unreinforced Ti-22Al-27Nb matrix alloy and a Ti-22Al-27Nb/TiB composite produced using a conventional ingot metallurgy method (IM composite) with relatively coarse (average diameter 5 μm and average length 40 μm) TiB particulates. These coarse TiB particulates in the IM composite were thought to provide only classical composite strengthening effects. On the other hand, the fine TiB particulates in the PM composite showed additional effects, such as blocking the movement of dislocations.     

Effects of fullerene derivatives on the gas permeability of thermoplastic polyurethane elastomers

In an effort to improve the gas barrier properties of thermoplastic polyurethane (TPU) elastomers, fullerene derivatives were added as fillers, and the resulting O₂ and CO₂ permeabilities were analyzed. The addition of 5 wt % polyhydroxylated fullerene {fullerenol [C₆₀(OH)_n] mixture, where n = 6–12} decreased the gas permeability by approximately 10–20%. According to the hole volumes computed with the results from positron annihilation lifetime spectroscopy, the addition of fullerene derivatives did not produce any changes in the hole volumes of the TPUs. Thus, the reduction in the TPU gas permeability was not caused by changes in the hole volumes. Instead, an inhibited diffusion of gas molecules by fullerene particles was deduced as the cause of the decrease in gas permeability from changes in the diffusion coefficient with temperature. The addition of urethanized fullerene, prepared through the chemical modification of fullerenol, markedly affected the TPU gas barrier properties. As compared to fullerenol addition, the gas barrier properties improved approximately fourfold for O₂ and approximately fivefold for CO₂. These results suggest that the dispersability of urethanized fullerene in TPU was higher than that of fullerenol. We found that the gas barrier properties were independent of the structure of polyol. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 39986.     

Quantitative analysis of the influence of conductors and ferromagnetic structures in power facilities on an ELF magnetic field environment using the finite element method

Recently, electric power transmission/substation systems need to be extended and they tend to be more compact. From the backgrounds of electromagnetic field environment, especially the magnetic field environment in and around electric power facilities becomes more important. However, many factors must be considered when investigating it, such as complicated current conditions, configurations of conductors and ferromagnetic structures, and so on. For more precise investigation of magnetic field environments, we must understand the quantitative influence of conductors and ferromagnetic structures. In this paper we describe how conductive and ferromagnetic materials influence the ELF magnetic field distribution. We carried out the measurement and finite element analysis of magnetic flux density distribution around an aluminum plate, a soft magnetic iron plate, and a 1/40 reduced model of an actual transmission tower. Based on the results, we clarified the influence of conductors and ferromagnetic substances on the magnetic flux density distribution around them. Finally, we showed the effectiveness of finite element analysis for evaluating the magnetic field around actual power facilities. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 140(3): 44–52, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10021     

Superconducting compact synchrotron light source

A superconducting compact synchrotron light source, the NIJI-III, has been completed. The development of the NIJI-III was assigned to Sumitomo Electric Industries Ltd. by the Research Development Corporation of Japan and was deemed successful in October 1991 with the attainment of the design goal of the stored beam current of 200 mA at the final beam energy of 600 MeV. The lattice has a four-sector configuration: four superconducting bending magnets and eight quadrupole magnets, achieving the optimum beam characteristics for lithography. The world's first superconducting bending magnet was developed and adapted, and was characterized by a cosθ type without an iron, a large bore of 200 mm, and a strong curvature of 0.5 m. Furthermore, a newly developed vacuum system and an rf system were installed. The high-speed electron-beam wobbling method was investigated at a 20-Hz triangular wave for the exposure of the vertical field of synchrotron light. It was demonstrated that the expansion of the vertical exposure area agreed with the theoretical calculation, and that there was no effect on the beam lifetime. The achievement of the NIJI-III can be expected to contribute much to the development of various research applications of synchrotron light.     

Selective expression of the scaffold protein JSAP1 in spermatogonia and spermatocytes

Scaffold proteins of mitogen-activated protein kinase (MAPK) intracellular signal transduction pathways mediate the efficient and specific activation of the relevant MAPK signaling modules. Previously, our group and others have identified c-Jun NH2-terminal kinase (JNK)/stress-activated protein kinase-associated protein 1 (JSAP1, also known as JNK-interacting protein 3) as a scaffold protein for JNK MAPK pathways. Although JSAP1 is expressed in the testis in adults, its expression during development has not been investigated. In addition, it is unknown which types of cells in the testis express the scaffold protein. Here, we examined the expression of JSAP1 in the testis of mice aged 14 days, 20 days, 6 weeks, and 12 weeks by immunohistochemistry and Western blotting. The specificity of the anti-JSAP1 antibody was evaluated from its reactivity to exogenously expressed JSAP1 and a structurally related protein, and by antigen-absorption experiments. The immunohistochemical analyses with the specific antibody showed that the JSAP1 protein was selectively expressed in the spermatogonia and spermatocytes, but not in other cell types, including spermatids and somatic cells, during development. However, not all spermatogonia and spermatocytes were immunopositive either, especially in the 12-week-old mouse testis. Furthermore, we found by Western blotting that the expression levels of JSAP1 protein vary during development; there is high expression until 6 weeks after birth, which approximately corresponds to the end of the first wave of spermatogenesis. Collectively, these results suggest that JSAP1 function may be important in spermatogenic cells during early postnatal development.     

Improvement in the durability of carbon black-supported Pt cathode catalysts by silica-coating for use in PEFCs

Commercially available Pt metal catalysts supported on carbon black (Pt/CB) for polymer electrolyte fuel cell (PEFC) cathodes were covered with silica layers to improve their durability under the severe cathode operating conditions. The Pt metal particles in the Pt/CB catalyst grew in size during the accelerated durability tests (potential cycling between 0.6 and 1.0 V vs. RHE in an aqueous HClO₄ electrolyte). Thus, the Pt/CB catalyst was seriously deactivated for the oxygen reduction reaction over the course of the durability tests. In contrast, the silica layers, which wrapped around the Pt metal particles in the silica-coated Pt/CB catalyst, prevented the migration of the Pt metal particles on the carbon supports and the diffusion of Pt cations out of the silica layers. Thus, the silica-coated Pt/CB catalysts maintained a high activity for the oxygen reduction reaction over the course of the durability tests. In addition, the silica-coated Pt/CB prepared from methyltriethoxysilane showed a higher activity than that prepared from tetraethoxysilane. The porous structures and hydrophobicity of silica prepared from methyltriethoxysilane promoted the diffusion of oxygen and water molecules in the silica layers of the silica-coated Pt catalysts.