The electrocatalytic activities of the Pd-doped MnO2 for the chlorine evolution reaction

The anodic evolution of chlorine on the massive β-MnO₂ doped with various amounts of Pd was investigated in acidic chloride solution. A second-order relation was found between the rate of the chlorine evolution reaction and the number of active Pd sites at the electrode surface. And it was confirmed that, in the relatively low doped electrodes, the active sites are more effectively dispersed on the surface with microscopic homogeneity. From the activation energies, it was also suggested that the reaction mechanism on the MnO₂ doped with relatively small amounts of Pd is somewhat different from that on the pure PdO electrode.     

Design of new catalysts for ecological high-quality transportation fuels by combinatorial computational chemistry and tight-binding quantum chemical molecular dynamics approaches

Recently, we introduced a concept of combinatorial chemistry to computational chemistry and proposed a new method called “combinatorial computational chemistry”, which enables us to perform a theoretical high-throughput screening of catalysts. In the present paper, we reviewed our recent application of our combinatorial computational chemistry approach to the design of new catalysts for high-quality transportation fuels. By using our combinatorial computational chemistry techniques, we succeeded to predict new catalysts for methanol synthesis and Fischer–Tropsch synthesis. Moreover, we have succeeded in the development of chemical reaction dynamics simulator based on our original tight-binding quantum chemical molecular dynamics method. This program realizes more than 5000 times acceleration compared to the regular first-principles molecular dynamics method. Electronic- and atomic-level information on the catalytic reaction dynamics at reaction temperatures significantly contributes the catalyst design and development. Hence, we also summarized our recent applications of the above quantum chemical molecular dynamics method to the clarification of the methanol synthesis dynamics in this review.     

Engineering Analysis and Design with ALE-VMS and Space–Time Methods

Flow problems with moving boundaries and interfaces include fluid–structure interaction (FSI) and a number of other classes of problems, have an important place in engineering analysis and design, and offer some formidable computational challenges. Bringing solution and analysis to them motivated the Deforming-Spatial-Domain/Stabilized Space–Time (DSD/SST) method and also the variational multiscale version of the Arbitrary Lagrangian–Eulerian method (ALE-VMS). Since their inception, these two methods and their improved versions have been applied to a diverse set of challenging problems with a common core computational technology need. The classes of problems solved include free-surface and two-fluid flows, fluid–object and fluid–particle interaction, FSI, and flows with solid surfaces in fast, linear or rotational relative motion. Some of the most challenging FSI problems, including parachute FSI, wind-turbine FSI and arterial FSI, are being solved and analyzed with the DSD/SST and ALE-VMS methods as core technologies. Better accuracy and improved turbulence modeling were brought with the recently-introduced VMS version of the DSD/SST method, which is called DSD/SST-VMST (also ST-VMS). In specific classes of problems, such as parachute FSI, arterial FSI, ship hydrodynamics, fluid–object interaction, aerodynamics of flapping wings, and wind-turbine aerodynamics and FSI, the scope and accuracy of the FSI modeling were increased with the special ALE-VMS and ST FSI techniques targeting each of those classes of problems. This article provides an overview of the core ALE-VMS and ST FSI techniques, their recent versions, and the special ALE-VMS and ST FSI techniques. It also provides examples of challenging problems solved and analyzed in parachute FSI, arterial FSI, ship hydrodynamics, aerodynamics of flapping wings, wind-turbine aerodynamics, and bridge-deck aerodynamics and vortex-induced vibrations.     

Preparation of Porous Ceramics with Calcium Metaphosphate Fiber Skeleton for Biomedical Use

High-strength calcium metaphosphate fibers for biomedical applications are extracted from crystallized products of calcium ultraphosphate glasses by aqueous leaching. In the present work, new types of porous ceramics with a skeleton composed of the crystalline fibers are prepared by heating the fibrous products extracted. The fibers in the ceramic are interlinked to each other by glassy phases formed during the heating. This porous material has a large porosity of >60%. The surface of the skeleton can be successfully converted into new calcium phosphate phases such as apatite by heating the porous material treated with a molten salt mixture of CaCl₂-Ca(NO₃)₂.     

Diffusion/adsorption model of cellulose dyeing. II. Ordinary cellulose–direct dye system

The diffusion and adsorption of C.I. Direct Yellow 12 and Blue 15 in water-swollen ordinary cellophane sheets were examined at various ionic strengths. The concentration dependence of apparent diffusion coefficients, D_c, for these dyes was obtained from the diffusion profiles in the substrate, which were measured by the use of the cylindrical film roll method. The decrease of apparent porosity with an increase in the amounts of adsorption was observed. To explain the diffusion/adsorption behaviors of these systems, a variable porosity model was proposed and was applied to analyze the concentration dependence of D_c's. The diffusion/adsorption behaviors of these dyes could be quantitatively described by this model at relatively low ionic strengths. At higher ionic strengths and/or lower values of C, i.e., at the large values of C_im/C_m, where the C's are the concentrations of immobilized (suffix im) and mobile (suffix m) species, it needed to introduce the concept of dynamic equilibria which occurred simultaneously with diffusion but deviated from the true equiliblia measured by the adsorption experiments.     

Prediction of the biologically active sites in eclosion hormone from the silkworm, Bombyx mori

The structure-activity relationship of eclosion hormone from the silkworm, Bombyx mori, was analyzed. First, the probable active residues in silkworm eclosion hormone and also tobacco hornworm eclosion hormone were predicted by the average distance map method. To examine the contributions of those residues to the activity of silkworm eclosion hormone, Gly-substituted mutants for those predicted residues were produced by site-directed mutagenesis and their activities were evaluated by a bioassay. Finally, Glu12, Met24 and Phe25 were estimated to be the crucial residues for the eclosion hormone activity. The possibility of the development of a blocker of an eclosion hormone receptor on the basis of the present work is also discussed.      

Reaction and diffusion of reactive disperse dye in nylon 6

The diffusion of a reactive disperse dye with a vinylsulfonyl group accompanied by simultaneous reaction with the amino end groups in nylon 6 was examined by the method of cylindrical film roll at 70°C and pH 2.2–8.0. The experimental diffusion profiles of the active and fixed species of the dye in nylon 6 were confirmed to be described by the diffusion equation accompanied by the chemical reaction with substrate taking the limited amount of the end groups into account, where the active species of dye were assumed to react only with the free base of amino end groups. The completion of the reaction with the amino end groups was observed in the first layer from the surface at pH 6.0–8.0. The value of diffusion coefficient was constant (8.0 × 10^?10 cm²/s) at all the pH's. The product of the second-order rate constant, k₂, of reaction of the dye and the dissociation constant, K_a, of the amino end groups was constant (k₂K_a = 4.0 × 10^?9 s^?1) at pH 2.2–8.0. The k₂ values of the reaction with various substrates for vinylsulfonyl and monochlorotriazinyl-reactive dyes were compared and the practical dyeing conditions were discussed.     

New class of cellulose fiber spun from the novel solution of cellulose by wet spinning method

A novel cellulose solution, prepared by dissolving an alkali-soluble cellulose, which was obtained by the steam explosion treatment on almost pure natural cellulose (soft wood pulp), into the aqueous sodium hydroxide solution with specific concentration (9.1 wt %) was employed for the first time to prepare a new class of multifilament-type cellulose fiber. For this purpose a wet spinning system with acid coagulation bath was applied. The mechanical properties and structural characteristics of the resulting cellulose fibers were compared with those of regenerated cellulose fibers such as viscose rayon and cuprammonium rayon commercially available. X-ray analysis shows that the new cellulose fiber is crystallographically cellulose II, and its crystallinity is higher but its crystalline orientation is slightly lower than those of other commercial regenerated fibers. The degree of breakdown of intramolecular hydrogen bond at C₃[X_am(C₃)] of the cellulose fiber, as determined by solid-state cross-polarization magic-angle sample spinning (CP/MAS) ¹³C NMR, is much lower than other, and the NMR spectra of its dry and wet state were significantly different from each other, indicating that cellulose molecules in the new cellulose fiber are quite mobile when wet. This phenomenon has not been reported for so-called regenerated cellulose fibers.     

Environmentally benign precipitation copolymerization of methacrylate ester and styrene to make polymeric microspheres in supercritical carbon dioxide

The polymeric microspheres were synthesized by the precipitation copolymerization of glycidyl methacrylate (GMA) with methacrylic acid(MAA) or 2‐hydoxyethyl methacrylate (2‐HEMA) containing styrene (ST) in SC‐CO₂. Scanning electron microscopy (SEM) showed that the products were spherical microparticles, with the addition of MAA and/or 2‐HEMA as the monomer, with diameter of 0.2–2 μm. The effects of copolymerization pressure, temperature, and ratios of GMA/MAA, ST, and/or GMA/2‐HEMA, on the particle size and morphology were investigated in detail. A new experiment setup is proposed for the large amount of production, based on the rule of lower monomer concentration, more stable system, and better use of the present polymerization apparatus. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2425–2431, 2007     

Ethylene carbonate-based organic electrolytes for electric double layer capacitors

A new electrolytic solution based on a mixed solvent of ethylene carbonate (EC) with sulfolane (SL) or -butyrolactone (-BL) has been examined as an electric double layer capacitor. Fundamental properties, such as electrolytic conductivity, viscosity, and thermal stability, were measured for solutions containing quaternary alkylammonium salts as the supporting electrolyte. Maximum conductivities were obtained for the solutions with mixed solvent of 20–40 mol % EC in the EC+-BL system: 1.2–1.3×10^–2S cm^–1 for EC+-BL dissolving 0.5 M Et₄ NBF₄ (Et=C₂H₅). The electrochemical and the thermal stabilities of the solution were dependent on the electrolytic salt as well as the solvent composition. A stable discharge capacitance and a high coulombic efficiency were obtained in a model capacitor using carbon fibre electrodes and the organic electrolyte of EC+-BL/Et₄NBF₄ (or EC+-BL/Et₄NPF₆).