The hydrogen permeation rate reached 860 mL/min with a single membrane. The value was achieved by the result of obtaining thin and large membranes with no defect using an electroless plating method. The obtained membranes were self-supported. They were separated from substrate with no damage by introducing a Pd-containing sacrificial layer with subsequent Pd nanoparticle activation, plating and mild removal. The increased Pd nucleus and homogeneous dispersion of Pd nuclei were effective for obtaining thin and large membranes without a pinhole. The membrane minimum thickness was less than 5 μm. The area size of obtained membranes was larger than 5600 mm2. Hydrogen permeation tests were conducted for the effective area of 1013 mm2. When a gas mixture including H2, CO, and CO2 was introduced into the feed side, gas chromatography detected no other gas but hydrogen in the permeation side. The hydrogen permeation flux data were evaluated using Sieverts’ law and the power law. The hydrogen permeation rate of the self-supported membrane was stable for nearly 1400 hrs.
The novel six-coordinate iron(II) complex [FeII(tpy)2][FeIII(Tp)(CN)3]2・2MeOH (1) was prepared, and its structure was successfully determined by single-crystal X-ray analysis. The compound is triclinic, space group P-1, with two molecules in a unit cell of dimensions a = 8.9547(16) Å, b = 14.450(3) Å, c = 23.098(5) Å, α = 88.090(11)°, β = 88.822(10)° and γ = 79.093(7)°. The crystal structure of 1 consists of a six-nitrogen-coordinate iron(II) cation, two [FeIII(Tp)(CN)3]- anions and two crystallization methanol molecules. The ligand-metal distances of Fe(II)-N, Fe(III)-NTp and Fe(III)-CCN indicate that Fe(II) and Fe(III) assume low-spin (LS) states. The magnetic susceptibility measurement shows that the value of χmT is 1.86 cm3 Kmol−1 at room temperature, which is consistent with the presence of one Fe(II) LS and two Fe(III) LS moieties.
Hydrogenated p+ and n+ doped silicon thin films deposited using radio frequency (13.56 MHz) plasma-enhanced chemical vapour deposition (PECVD) are studied in detail using micro Raman spectroscopy to investigate the impact of doping gas flow, hydrogen dilution ratio, film thickness, and substrate type on the doped silicon thin film characteristics. In particular, by deconvoluting the micro Raman spectra into amorphous and crystalline components, quantitative and qualitative information on bond angle disorder, bond length, nature of film stress, and film crystallinity can be extracted and used to predict the performance of these doped silicon thin films in heterojunction silicon wafer solar cells. By applying optimised doped silicon thin film deposition conditions to our heterojunction carrier lifetime structures and cell structures, we demonstrate an efficient field-effect passivation from these doped layers with improvement in implied open-circuit voltage and effective minority carrier lifetimes across the injection levels of interest. In particular, the device relevant heterojunction carrier lifetime structure [μc-Si:H(p)/a-Si:H(i)/c-Si(n)/a-Si:H(i)/μc-Si:H(p)] demonstrates an effective minority carrier lifetime of 2.4 ms at an injection level of 1015 cm-3, and a high implied open-circuit voltage of 723 mV.
The electrospun nanofibers of TiO2 and Nb doped TiO2 (NTO) were mixed into the TiO2 mesoporous layer in the photoelectrodes of dye sensitized solar cells (DSCs) as a conductive agent, and their effects to the carrier mobility and photovoltaic characteristics were examined. From the time-transient spectra of photocurrent excited by the pulse laser irradiation, it was found that the diffusive velocity of photoexcited carriers was increased by the mixture of the bundle of electrospun nanofibers, and the increase resulted in the improvement of short-circuit current density and efficiency. The enhancement of carrier mobility was also observed due to the band bending at the interface of NTO/TiO2. Thus, it was found that electrospun nanofibers of NTO were a good conductive agent for the accumulation of photoexcited carriers in dye/TiO2 nanoparticles.
Synthesis of zeolite from diatomite was conducted by using dilute alkali, 0.15M and 0.3M NaOH solution. Preheating treatment at 70ºC for 6 hour before hydrothermal reaction at 170ºC was necessary for activation. The synthesis product was mordenite type zeolite. The zeolite has high capacity for VOCs adsorption, represented by formaldehyde and toluene.
Anion exchange membranes for alkaline fuel cells based on phenolphthalein derivatives were prepared. First, phenolphthalein was derivatized with N,N,-dimethyl-1,3-propanediamine (DMPDA) and N,N,-dimethyl-1,2-ethanediamine (DMEDA). Copolymers containing DMPDA and DMEDA were then prepared via step-condensation or polycondensation polymerization using 4,4'-dichlorodiphenylsulfone or 2,6-dichlorobenzonitrile as an activated dihalide. These copolymers were first solution cast and then reacted with methyl iodide to generate quaternary ammonium groups. The new anion exchange membranes showed high anion conductivity of>10 mS/cm at 30 °C. Thorough investigation of the chemical stability of the copolymers under basic conditions indicated that DMPDA-containing copolymers showed higher stability than DMEDA-containing copolymers. The relationship between the chemical structure and stability was systematically studied.
Grain boundary sliding in various grain boundaries (pure, with segregation, and heterophase boundary) was investigated with molecular dynamics simulations and first-principles calculations from the atomic viewpoints. In the pure and segregated grain boundaries which have same grain boundary structure, the behavior of atomic movement during the sliding is same, and there was no correlation between the sliding rate and the grain boundary energy. First-principles calculations revealed that the sliding rate calculated by the molecular dynamics simulations increases with decreasing minimum charge density at the bond critical point in the grain boundary. In the heterophase boundary, the atomic movement was different from the pure and segregated grain boundaries according to the disordered grain boundary structure. Thus, the sliding rate depends on atomic movement enhanced by the defect structure at grain boundaries.
Magnetic separation of a phosphor having high magnetic susceptibility from waste phosphors was tried using a high gradient magnetic separator. Since the green phosphor LAP (LaPO4: Ce, Tb) has high magnetic susceptibility, it could be separated by this method. Repeating the separation procedure, most LAP could be recovered, and LAP purity of 87% was obtained. This method is a promising method of separating a single species of phosphor.
Woodceramics, a substance based on woody materials carbonized at elevated temperatures after impregnating with phenolic resin, have been developed as a new kind of porous carbonaceous material. To expand the industrial application, we attempted to produce amorphous carbon films were RF magnetron sputtering using woodceramics as its target. As a result, typical amorphous carbon films were successfully produced using woodceramics, and the films were characterized by X-ray diffractometry, Raman spectroscopy and X-ray photoelectron spectroscopy. The films produced were composed of carbon turbostratic structure or amorphous whose electron configurations consisted of sp2 and sp3. The ratio of sp3 bonding in the films were about 53% just after the sputtering, but the number increased to about 82% after etching the material using argon ions. Fundamental mechanical properties such as hardness and friction coefficient were also measured and taken into account.
A new process for silica nano-powder dispersion in an anode electrode paste for direct ethanol fuel cells was studied by applying an excess amount of solvent (acetone) that easily evaporates after mixing the paste. A well-dispersed anode electrode results in more efficient output power than an agglomerated anode paste. Nano-silica will act as an oxidant to acetaldehyde and can form a structure that supports increased ethanol penetration into the electrode. Using gas chromatography, the acetaldehyde concentration was measured to determine the mechanism of the reaction occurring in the fuel cells.
Bismuth plated films have been used as a high-temperature joining in SiC power device because of their outstanding melting point. Electroless bismuth plating intended to have a “weak acidic” was investigated using Sn2+ ion as the reducing agent and citrate as the complexing agent. Complex baths exhibited good stability, and pure bismuth films were deposited. Experiments in polarization characteristics confirmed the mixed potential theory including local potential-current relationships for bismuth deposition.
In order to clarify complicated phase behaviors and to obtain a unified explanation in such sequential phase transitions, formation of three kinds of tetragonal phases with a fundamental structure (I4/mmm) and the superstructures (P42/mnm and Ccmm) for BaTb2Mn2O7 are mainly discussed in this study. Single crystal of this compound was also grown by Floating Zone method. The crystal structure was analyzed by four circle X-ray method. As grown single crystal showed the tetragonal phase with a superstructure with the lattice parameters of √2a x √2a x c (a and c are lattice parameters of fundamental tetragonal cell). Thermal anomalies were observed at 440 K and 740 K from DSC curve. When this as-grown specimen was annealed in purified argon atmosphere at 1373K for several days and quenched to room temperature, this phase changed into the fundamental tetragonal phase. On the one hand, When same specimen was annealed in purified argon atmosphere at 573 K for several days and slowly cooled to room temperature, phase changed into the orthorhombic space group Ccmm. As grown crystals have P42/mnm type tetragonal phase within the middle temperature, Ccmm type orthorhombic phase at room temperature and I4/mmm type tetragonal phase at high temperature.
Herein, we describe a facile and green method to prepare fluorescent polymer particles by combined use of enzymatic miniemulsion polymerization and click reaction. Firstly, alkyne-bearing polymer particles were prepared by HRP-mediated miniemulsion polymerization of styrene with clickable surfmer (surfactant + monomer) 1. Then, azide-bearing fluorescence compound, i.e., dansyl azide compound 2, was introduced to polymer particles surface via click reaction using Cu(I) catalyst. This methodology will be applied to a broad range of azide-bearing compounds to generate functional polymer particles. Since both enzymatic miniemulsion polymerization and click reaction are conducted at room temperature in water, present method offers a practical and environmental friendly method for preparation of functional polymer particles.
Self-assembled (SA) monolayers of pendant-tail alkoxysilanes, 3-mercaptopropyltrimethoxy-silane and bis[3-(triethoxysilyl)propyl]disulfide, were prepared on silicon wafers and exposed to a UV/O3 environment for chemical modification of sulfurous groups. The change in chemical state and the decomposition of film molecules due to the UV/O3 treatment were investigated by X-ray photoelectron spectroscopy (XPS). The UV/O3 exposure induced oxidation of the terminal thiol and disulfide groups into predominantly sulfo or sulfonate groups. The monolayer degradation, indicated by the decrease in surface concentration of carbon species, gradually progressed as prolonging the exposure time, but a surface with a desired fraction of the oxidized sulfurous groups could be prepared with a minimal decomposition degree under an appropriate exposure time. The XPS spectra were also measured for human hair surfaces. It was implied that the oxidized SA monolayers have the same oxidized sulfur species as those on the damaged hair surfaces in terms of the binding energy. This work demonstrates that the UV/O3 exposure to the sulfurous group-terminated monolayers is an easy and useful approach to obtain the surfaces covered with the highly oxidized sulfurous groups. Such surfaces are utilizable as models of damaged hair surface for a study on adsorption characteristics of hair-conditioning agents.
We report a technique of direct patterning of Cu thin films on Pd nanoparticles photodeposited on layer-by-layer (LbL) films consisting of sodium polystyrene sulfonate (PSS) and TiO2 nanoparticles on plastic sheets. The LbL films were formed on plastic sheets by soaking the plastic sheets alternately in PSS acidic solution and TiO2 nanoparticle dispersion. The amounts of PSS and TiO2 nanoparticles in the LbL films were proportional to the number of immersion. Pd nanoparticles were formed on the PSS/TiO2 LbL films by irradiation with UV light through metal masks in acidic solution of palladium chloride. The amount of the Pd nanoparticles increased with increasing UV irradiation time. Cu films were deposited selectively on the Pd nanoparticles in the electroless plating bath of Cu. The results of the energy dispersive X-ray analysis and the elemental mapping were consistent with the above results. With an increase in the layer number of the LbL films, the growth rate of Cu films increased probably due to an increase in the amount of Pd nanoparticles on the LbL films. This technique allows for the reduced material consumption and fabrication steps in direct metal patterning on plastic sheets using light irradiation.
The syntheses of peripherally tetra-substituted nickel(II), copper(II), zinc(II), and metal-free, phthalocyanines containing 4-aryl (4-phenylsulfanyl, 4-phenylsulfinyl, and 4-phenylsulfonyl) and 4-alkyl (4-iso-amylsulfanyl, 4-iso-amylsulfinyl, and 4-iso-amylsulfonyl) groups were demonstrated to investigate water-dispersible phthalocyanine colloids fabricated by a conventional reprecipitation method. Dynamic light scattering measurements revealed that the prepared colloids were monodispersive.
We fabricated a polymer nanosphere multilayered organization consisting of aromatic polyamides with rigid main chains and flexible side chains by the Langmuir–Blodgett (LB) technique, which resulted in a high regularity along the c-axis. The particle arrangement was estimated by performing out-of-plane X-ray diffraction (XRD) analysis and atomic force microscopic (AFM) observation. The results suggest that a double-particle layered structure (Y-type) is formed by the LB technique, forming amphiphilic particles at the air/water interface. In addition, copolymers with highly hydrophobic carbazole components and both hydrogenated and fluorinated side-chains also formed polymer nanoparticle at the air/water interface. Formation of single-particle layered structure was indicated. Therefore, it is possible to control the formation of single- and double-particle layered structure. Further, it was found that multiparticle layered organization of polymer nanospheres and polymer nanosheets could be formed simultaneously with the same component material.
A "topological polymer chemistry" as a new concept in polymer science at the air/water interface is investigated by using amphiphilic linear and cyclic block copolymers consisting of butyl acrylate and ethylene oxide. The relatively stable monolayers of these two kinds of amphiphilic copolymers were formed at the air/water interface. In addition, these two kinds of amphiphilic copolymers constructed highly ordered Langmuir-Blodgett (LB) multilayers. In order to estimate the layered regularity under high temperature, the temperature-controlled out-of-plane X-ray diffraction (XRD) of LB films of amphiphilic linear and cyclic block copolymers was obtained. As a result, excellent heat-resistant propertyies of organized molecular films of the cyclic copolymer were confirmed. At room temperature, both copolymers showed clear diffraction peaks based on the formation of highly ordered layer structures. However, in the case of linear copolymers, layered structures were gradually disordered with heating. On the other hand, regularity of LB multilayers of the cyclic copolymers did not change with heating up to 50 °C. In this case, higher order reflections (d002, d003) of XRD are also unchanged, which means the formation of highly ordered regularity.
A "topological polymer chemistry" at air/water interface is investigated by using an amphiphilic linear and cyclic block copolymers. A cyclic copolymer and two kind of linear polymers (AB-type diblock and ABA-type triblock copolymers) with same components were used in the study. The relatively stable monolayers of these three kinds of copolymers were formed at the air/water interface. The analogous condensed tendency and temperature dependency were observed in surface pressure-area isotherms of three kinds of monolayers. It is considered that molecular orientation at air/water interface of two kinds of liner block copolymers is similar to that of cyclic block copolymer. From the result of atomic force microscopic observation of transfered films, monolayers of the three kinds of polymers have formed a very similar morphology at mesoscopic scale under the conditions at room temperature and the constant compression speed. It finds that ABA type triblock liner copolymer formed fiber-like surface morphology by the two-dimensional crystallization based on the low compression speed. On the other hand, cyclic block copolymer formed shapeless domain.
Ultrathin films of regularly adsorbed biological molecules have been fabricated by means of the modified Langmuir-Blodgett (LB) method using an organo-modified montmorillonite (MMT). Adsorption of enzymes onto the anionic silicate surface could be confirmed by a comparison of the IR spectra of multilayers of organo-modified clay and those of lysozyme-adsorbed films. The IR bands of lysozyme were clearly confirmed in the spectra of enzyme-adsorbed multilayers. Enzyme activity of the enzyme-adsorbed multilayers was maintained at high temperatures, up to 160 °C. This suggests that three-dimensional structure of enzyme inserted in clay particle were maintained at high temperature.
Formation and structure of single particle layer of organo-zinc oxide are investigated by surface pressure-area (π-A) isotherm, out-of-plane X-ray diffraction (XRD) analysis, and atomic force microscopy (AFM). In this study, solubilization technology of inorganic fine particles into general solvent have proposed and formation technology of single particle layer have established by using that inorganic solution as "spreading solution" of the interfacial film. The surface modification of ZnO is performed using long-chain carboxylic acid. Accordingly, it is easily achieve a regular arrangement of ZnO to overcome the relatively weak van der Walls interactions between the inorganic materials. A Langmuir monolayer of these particles is condensed. A multi-particle layered structure is constructed by the Langmuir-Blodgett (LB) technique. The results of the out-of-plane XRD measurements of the single particle layer for organo-ZnO clearly confirmed a sharp peak at 42 Å. This reflection have came from distance between ZnO in layer structure. AFM image of this single particle layer of organo-ZnO showed particle assembly with uniform height of 60 nm. These aggregated particles formed large two-dimensional crystal. That is to say, a regular periodic structure along the c-axis and condensed single particle layer have been fabricated by Langmuir and LB techniques.
Bioluminescence is widely distributed in various microorganisms, insects, shrimps, squid and fish. Bioluminescence can be also used as a reliable reporter for the assessment or monitoring of various aquatic samples containing toxicants such as pesticides, polychlorinated Biphenyls (PCBs), polyaromatic hydrocarbons, fuels, and heavy metals. In this study, luciferase were cultured from squid. Structured molecular films of adsorbed luciferase have been fabricated by means of a modified LB method using organo-modified clay. Chemisorption of luciferase to the anionic montmorillonite (MMT) surface was confirmed by a comparison between infrared spectra of multilayers of organo-clay and of chemisorbed luciferase. The bands of νC=O and δN-H of luciferase were clearly identified in the spectra of multilayers coated with chemisorbed biomolecules. Luminescence spectra of buffer solution containing luciferase and multilayers of clay/luciferase suggest that enzyme activity were maintained in the case of multilayers of clay/luciferase.