Distribution Behavior of Nb,Ta, and Pa as Homologues of Db in Cation Exchange and Solid-Liquid and Liquid-Liquid Extractions by Aliquat 336 from Hydrochloric Acid

Detailed chemical studies on transactinide elements will clarify their characteristic properties caused by strong relativistic effect. In this work, to realize chemical study on transactinide element ₁₀₅Db, cation exchange, and solid-liquid and liquid-liquid extractions of micro amounts of Nb, Ta (homologues of Db), and Pa (pseudo homologue) by Aliquat 336 were performed employing hydrochloric acid. Clearly different chloride complex formations and distribution reaction kinetics were observed among these elements, and the present results are useful for studying the chemical properties of Db. Based on these results, we propose suitable experimental conditions for Db.     

Graft copolymerization onto cellulose by ceric ion initiator system: Effects of kind of acid and irradiation with ultraviolet light

The effects of kind of acid and irradiation of ultraviolet light on the graft copolymerization of methyl methacrylate onto cellulose with adsorbed ceric ion were investigated. Irrespective of ultraviolet light irradiation, the amount of reduced ceric ion in the reaction systems was increased in the order HCl > HClO₄ > HNO₃ > H₂SO₄, and the number of grafts formed was increased in the order HClO₄ > HNO₃ > HCl > H₂SO₄. Thus, it was definitely observed that the graft copolymerization is affected by the kind of acid. Ultraviolet light remarkably accelerated the reduction of ceric ion adsorbed on cellulose in the various acid mediums, but decreased the efficiency of graft formation. The most favorable results for the formation of grafts were obtained in the system in which HClO₄ and ultraviolet irradiation was employed. A combination of H₂SO₄ and ultraviolet irradiation resulted in the lowest per cent grafting and average molecular weight of grafts. It was found that H₂SO₄ characteristically dissolves out ceric ion adsorbed into an aqueous solution and accelerates the formation of homopolymer.     

Direct Reprogramming and Induction of Human Dermal Fibroblasts to Differentiate into iPS-Derived Nucleus Pulposus-like Cells in 3D Culture

Intervertebral disc (IVD) diseases are common spinal disorders that cause neck or back pain in the presence or absence of an underlying neurological disorder. IVD diseases develop on the basis of degeneration, and there are no established treatments for degeneration. IVD diseases may therefore represent a candidate for the application of regenerative medicine, potentially employing normal human dermal fibroblasts (NHDFs) induced to differentiate into nucleus pulposus (NP) cells. Here, we used a three-dimensional culture system to demonstrate that ectopic expression of MYC, KLF4, NOTO, SOX5, SOX6, and SOX9 in NHDFs generated NP-like cells, detected using Safranin-O staining. Quantitative PCR, microarray analysis, and fluorescence-activated cell sorting revealed that the induced NP cells exhibited a fully differentiated phenotype. These findings may significantly contribute to the development of effective strategies for treating IVD diseases.     

Propagation characteristics of impulse creepage discharge in perfluorocarbon liquid

In this paper, the propagation characteristics of a creepage discharge on the surface of a solid insulator with a back electrode in perfluorocarbon liquid under an impulse voltage application are investigated. The propagation process is observed in detail by means of a high‐speed schlieren optical technique, and simultaneously waveforms of a current and a charge are also measured. Consequently, the polarity effect of the streamer propagation and the positive streamer which propagates stepwise can be seen. The latter is concurrent with the sparse current pulse which corresponds to the charge step‐variation. These results are compared with ones obtained in transformer oil. © 2000 Scripta Technica, Electr Eng Jpn, 131(4): 19–28, 2000     

Giant electric double-layer capacitance of heavily boron-doped diamond electrode

The physical and electrochemical properties of boron-doped polycrystalline diamond electrodes, prepared with various B/C ratio, i.e., 0.1%, 0.5% (BDD-A), 1% (BDD-B), and 5% (BDD-C), were investigated. Electrochemical measurements of the heavily boron-doped films (BDD-C) showed giant electric double-layer capacitance and activity which is significantly larger than BDD-A and BDD-B as well as glassy carbon electrodes. However, interestingly, actual boron concentration of BDD-C was observed to be almost the same as that of BDD-B by secondary ion mass spectroscopy (SIMS) and glow discharge optical emission spectroscopy (GDOES) analysis. It is suggested that the large capacitance is due to a few sp²-bonded carbon impurities, which was observed only in BDD-C, although the amount of the sp²-bonded nondiamond species are very small. In the present work, the reason for the interesting electrochemical properties of heavily boron-doped diamond electrodes is discussed. Furthermore, dimensional stability of the electrodes was also confirmed by conducting harsh anodic treatment.     

Surface treatment of ferromagnetic nanoparticle-assembly by UV irradiation with ozone

Fe-Pt nanoparticles of 3.5 nm in average particle diameter are obtained with the simultaneous chemical reduction of platinum acetylacetonate and the thermal decomposition of iron pentacarbonyl. Because the as-synthesized particles are superparamagnetic at room temperature, they must be transformed to L1₀ ordered phase by annealing at temperatures above 773 K to apply to high-density magnetic recording media. However, the annealing at such high temperatures induces the coalescence and inter-particle sintering. In the present paper, to solve the problem caused by the annealing, we use ultraviolet-ozone treatment to modify particle surface. Even after annealing at 773 K, the crystalline size is kept at 4.4 nm. Furthermore, coercivity is higher than that without the ultraviolet-ozone treatment.     

Microphase-separated structure and mechanical properties of novel polyurethane elastomers prepared with ether based diisocyanate

A diisocyanate baring ether bonds, 1,2-bis(isocyanate)ethoxyethane (TEGDI), was used for the preparation of polyurethane elastomers (PUEs). The PUEs were synthesized with either TEGDI or HDI, poly(oxytetramethylene) glycol (PTMG), and curing agents by a prepolymer method. 1,6-Hexamethylene diisocyanate (HDI) was also used as a control diisocyanate. The TEGDI-based PUEs exhibited highly softened property on account of flexibility of TEGDI itself and weaker phase separation. Another TEGDI-based PUEs were prepared with either poly(oxypropylene) glycol (PPG) or poly(caprolactone) glycol (PCL). Microphase-separated structure of these TEGDI-based PUEs are quite different from those with general diisocyanates and the PUEs were made be greatly softened.     

Analysis of proton exchange membrane fuel cell catalyst layers for reduction of platinum loading at Nissan

The biggest issue that must be addressed in promoting widespread use of fuel cell vehicles (FCVs) is to reduce the cost of the fuel cell system. Especially, it is of vital importance to reduce platinum (Pt) loading of catalyst layers (CLs) in the membrane electrode assembly (MEA) of a proton exchange membrane fuel cell (PEMFC). In order to lower the Pt loading of the MEA, mass transport of reactants related to the performance in high current density should be enhanced significantly as well as kinetics of the catalyst, which can result in the better Pt utilization and effectiveness. In this study, we summarized our analytical approach and methods for reduction of Pt loading in CLs. Microstructure, mass transport properties of the reactants, and their relation in CLs were elucidated by applying experimental analyses and computational methods. A simple CL model for I–V performance prediction was then established, where experimentally elucidated parameters of the microstructure and the properties in CLs were taken into account. Finally, we revealed the impact of lowering the Pt loading on the transport properties, polarization, and the I–V performance.     

Effects of aging and moisture on the dynamic viscoelastic properties of oriental lacquer (urushi) film

The effects of aging and moisture on the dynamic viscoelastic properties of three oriental lacquer films were investigated. With aging over 1000 days at room temperature, the glass‐transition temperature of the lacquer films (T_α) shifted to higher temperatures, the maximum loss tangent (tanδ_α) decreased, and the storage modulus at 20°C (E) increased. These changes were analogous irrespective of lacquers. With increasing moisture content, E decreased and tanδ increased at room temperature. Although the equilibrium moisture content of the virgin lacquer (sap) film was higher than that of the clear lacquer film, its E and tanδ were more stable with an increase of moisture content. It was speculated that the polysaccharides aggregated in the sap film did not effectively contribute to the mechanical properties of the film, while their hygroscopicity resulted in higher moisture content. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2288–2294, 2002