Hokkaido University Collection of Scholarly and Academic Papers
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HUSCAP (Hokkaido University Collection of Scholarly and Academic Papers) contains peer-reviewed journal articles, proceedings, educational resources and any kind of scholarly works of Hokkaido University.
Mostrando recursos 1 - 20 de 1.797
1.
Comparative Enzymatic Analysis of Azoreductases from Bacillus sp. B29 - Ooi, Toshihiko; Shibata, Takeshi; Matsumoto, Ken'ichiro; Kinoshita, Shinichi; Taguchi, Seiichi
We cloned and expressed two genes encoding azoreductase homologes, AzrB and AzrC, from Bacillus sp. B29. Purified recombinant AzrB and AzrC were homodimers with 23kDa identical subunits, and were flavoproteins. NADH was preferred as electron donors for both azoreductases. The azoreductases showed optimal activities at 70℃ (AzrB) and 55℃ (AzrC), and retained activities up to 55℃ (AzrB) and 50℃ (AzrC) after incubation for 1 h. Other enzymatic properties, including the substrate specificities of both azoreductases, were also investigated.
2.
Relationship between bone tissue strain and lattice strain of HAp crystals in bovine cortical bone under tensile loading. - Fujisaki, Kazuhiro; Tadano, Shigeru
Cortical bone is a composite material composed of hydroxyapatite (HAp) and collagen. As HAp is a crystalline structure, an X-ray diffraction method is available to measure the strain of HAp crystals. However, HAp crystals in bone tissue have been known to have the low degree of crystallization. Authors have proposed an X-ray diffraction method to measure the lattice strain of HAp crystals from the diffusive intensity profile due to low crystallinity. The precision of strain measurement was greatly improved by this method. In order to confirm the possibility of estimating the bone tissue strain with measurements of the strain of...
3.
Co-deposition of Al-Cr-Ni alloys using constant potential and potential pulse techniques in AlCl3-NaCl-KCl molten salt - Ueda, Mikito; Kigawa, Hirokuni; Ohtsuka, Toshiaki
To improve the oxidation resistance of TiAl intermetallic compound under high temperature condition, cathodic co-deposition of Al-Cr and Al-Ni alloy was carried out by constant potential control or potential pulse control in AlCl3-NaCl-KCl molten salt containing CrCl2 and/ or NiCl2 at 423 K. Cathodic reduction of Ni and Cr starts at potential of 0.8 and 0.15 V vs. Al/Al3+ in the molten salt, respectively. The co-deposition of Al, Cr, and Ni occurred at potentials more negative than -0.1 V to form a mixture of intermetallic compounds of Cr2Al, Ni3Al, and Al3Ni. Concentration of Cr in the deposit was enhanced to...
4.
Numerical reconstruction of an infrared wavefront utilizing an optical phase modulation device - Miyamoto, Naoki; Nisiyama, Shusuke; Tomioka, Satoshi; Enoto, Takeaki
We utilize nitroanisole, that absorbs infrared(IR) radiation as heat, as an optical modulation device based on a thermal process. The nitroanisole exhibits a thermal lens effect, i.e. a temperature dependent refractive index. Hence, the nitroanisole can induce phase modulation to visible light, in direct response to intensity of the incident IR radiation. The proposed method can be used to obtain the phase modulation distribution that corresponds to the IR intensity distribution, i.e. the IR hologram itself, on the nitroanisole by examining the phase map of visible light that is modulated upon passing through the nitroanisole. The IR wavefront can be...
6.
Selective optical probing of the charge-density-wave phases in NbSe3 - Shimatake, K.; Toda, Y.; Tanda, S.
We report a study of the ultrafast single particle dynamics in quasi-one-dimensional NbSe3 whisker crystals using a two-color pump-probe measurement. A selective enhancement of the relaxation dynamics connected with one of the two charge-density-wave (CDW) phases was realized by tuning the probe energy to around 1.5 eV, in which the temperature dependence across the corresponding phase transition shows a pronounced anomaly. A similar selective excitation was possible in the coherent CDW oscillation.
7.
Pulse radiolysis studies of the reactions of bromine atoms and dimethyl sulfoxide-bromine atom complexes with alcohols - Sumiyoshi, Takashi; Fujiyoshi, Ryoko; Katagiri, Miho; Sawamura, Sadashi
Dimethylsulfoxide (DMSO)–Br complexes were generated by pulse radiolysis of DMSO/bromomethane mixtures and the formation mechanism and spectral characteristics of the formed complexes were investigated in detail. The rate constant for the reaction of bromine atoms with DMSO and the extinction coefficient of the complex were obtained to be 4.6×109 M−1 s−1 and 6300 M−1 cm−1 at the absorption maximum of 430 nm. Rate constants for the reaction of bromine atoms with a series of alcohols were determined in CBrCl3 solutions applying a competitive kinetic method using the DMSO–Br complex as the reference system. The obtained rate constants were 108 M−1...
8.
High inoculation cell density could accelerate the differentiation of human bone marrow mesenchymal stem cells to chondrocyte cells. - Takagi, Mutsumi; Umetsu, Yousuke; Fujiwara, Masashi; Wakitani, Shigeyuki
The effects of the density of human mesenchymal stem cells (MSCs) on their differentioation to chondrocytes in a differentiation medium supplemented with dexamethasone, TGFβ3, and IGF-1 were investigated for the regenerative therapy of cartilage. The increase in the initial density of MSCs from 0.05×104 to 0.9×104 cells/cm2 accelerated the increase in the expression level of aggrecan mRNA during the differentiation culture for 7 d. The conditioned medium harvested at 7 d from the differentiation culture with an initial MSC density of 0.3×104 cells/cm2 accelerated the initial increase in the expression level for 3 d in the differentiation culture with an...
9.
Encapsulation-release property of amphiphilic hyperbranched d-glucan as a unimolecular reverse micelle - Kitajyo, Yoshikazu; Imai, Tomoko; Sakai, Yoko; Tamaki, Masaki; Tani, Hirofumi; Takahashi, Kenji; Narumi, Atsushi; Kaga, Harumi; Kaneko, Noriaki; Satoh, Toshifumi; Kakuchi, Toyoji
The synthesis of a novel unimolecular reverse micelle, the hyperbranched d-glucan carbamate (3), was accomplished through the carbamation reaction of the hyperbranched d-glucan (1) with the N-carbonyl l-leucine ethyl ester (2) in pyridine at 100 °C. Polymer 3 was soluble in a large variety of organic solvents, such as methanol, acetone, chloroform, and ethyl acetate, and insoluble in water, which remarkably differed from the solubility of 1. The degree of carbamate substitution (DS) for 3 was controlled by the feed rate of 2, and the DS values were in the range of 46.0–93.7%. Polymer 3 possessed the encapsulation ability for...
10.
Ellipsometry of passive oxide films on nickel in acidic sulfate solution - Iida, Masahede; Ohtsuka, Toshiaki
Nickel passive film has been studied in acidic sulfate solutions at pH 2.3 and 3.3 by ellipsometry. During anodic passivation followed by cathodic reduction, the roughness increases with dissolution of nickel, being indicated by gradual decrease of reflectance. However, the ellipsometric parameters, Ψ (arctan of relative amplitude ratio) and Δ (relative retardation of phase), are relatively insensitive to the roughness increase. From the change of Ψ and Δ, δΨ and δΔ, during the anodic passivation and reduction, thickness of the passive oxide film was estimated with assumption of refractive index of nf = 2.3 of the film. The thickness estimated...
11.
Characteristics of suspended sediment material transport in the Ishikari Bay in snowmelt season - Le, Viet Son; Yamashita, Toshihiko; Okunishi, Takeshi; Shinohara, Ryuichiro; Miyatake, Makoto
The present paper aims at studies of the suspended sediment transport in inner Ishikari Bay in snowmelt season using a numerical approach and field observation data. The sediment transport and bottom boundary layer models are coupled into the Princeton Ocean Model to compute suspended sediment concentration in the system. The following findings have been deduced: (1) The suspended sediment transport in the study area in snowmelt season is dominated by the sediment discharge from the Ishikari River. The effect of sediment resuspension due to wave current interaction is limited to a very shallow area along the coast. (2) A comparison...
12.
Coherent shear phonon generation and detection with picosecond laser acoustics - Matsuda, O.; Wright, O. B.; Hurley, D. H.; Gusev, V.; Shimizu, K.
Measurements on a film of silica on crystalline zinc using picosecond laser acoustics are theoretically analyzed to quantitatively explain the generation and detection of picosecond shear and longitudinal-acoustic waves. The theory encompasses the scattering of obliquely incident probe light of arbitrary polarization by a depth-dependent anisotropic permittivity modulation in a multilayer, including terms arising from the photoelastic effect, interface displacements, and local rotations. Sound velocities, ultrasonic attenuation, and photoelastic constants are experimentally derived.
13.
The Role of Rusts in Corrosion and Corrosion Protection of Iron and Steel - Tamura, Hiroki
The processes of atmospheric corrosion of iron and steel and the properties of corrosion products (rusts) are modeled based on a quantitative evaluation of the chemical reactions pertaining to corrosion to elucidate the conditions with which corrosion-protective rust films form. Based on the model, it is suggested that in the initial stage of corrosion, in the rusts, the pH of the aquatic system is maintained at 9.31 owing to an equilibrium with iron(II) hydroxide and the rate of air-oxidation at this pH is very fast, and that dense, self-repairing rust films form, protecting the underlying iron and steel. However, after...
14.
Fabrication of a three-dimensional micro-manipulator by laser irradiation and electrochemical techniques and the effect of electrolytes on its performance - Kikuchi, T.; Akiyama, Y.; Ueda, M.; Sakairi, M.; Takahashi, H.
Ribbon type and three-dimensional micro-actuators, consisting of three-layer structure of acrylic acid resin / Au / polypyrrole, were fabricated by aluminum anodizing, laser irradiation, and electrochemical techniques, and their performance was examined. Anodized aluminum specimens were irradiated with a pulsed Nd-YAG laser to remove anodic oxide films locally, and then an Au layer was deposited at the area where film had been removed. The subsequent electrophoretic deposition of acrylic acid resin on the Au layer, dissolution of anodic oxide film and the metal substrate, and deposition of polypyrrole on backside of Au layer by electro-polymerization enabled the fabrication of a...
15.
Fabrication of Three-Dimensional Platinum Microstructures with Laser Irradiation and Electrochemical Technique - Kikuchi, T.; Takahashi, H.; Maruko, T.
Three-dimensional platinum microstructures were fabricated by successive procedures: aluminum anodizing, laser irradiation, nickel / platinum electroplating, and removal of the aluminum substrate, the oxide films, and the nickel metal layer. Aluminum plates and rods were anodized in an oxalic acid solution to form porous type oxide films. The anodized specimens were immersed in a nickel electroplating solution, and then irradiated with a pulsed Nd-yttrium aluminum garnet (YAG) laser beam to remove the anodic oxide film with a three-dimensional XYZθstage. The specimens were cathodically polarized in the nickel and a platinum electroplating solution to form the metal micropattern at the laser-irradiated...
16.
Local Deposition of Polypyrrole on Aluminum by Anodizing, Laser Irradiation, and Electrolytic Polymerization and Its Application to the Fabrication of Micro-actuators - Akiyama, Y.; Kikuchi, T.; Ueda, M.; Iida, M.; Sakairi, M.; Takahashi, H.
Polypyrrole was deposited at selected areas on aluminum by anodizing, laser irradiation, and electrolytic polymerization, and the application of the technique for fabricating micro-actuators was attempted. Aluminum specimens covered with porous type anodic oxide films were irradiated with a pulsed Nd-YAG laser to remove the oxide films locally, and then thin Ni layers were deposited at areas where film had been removed. Polypyrrole could be successfully deposited only on the Ni layer by anodic polarization of the specimens in pyrrole monomer solution, and a polypyrrole / Ni bilayer-structure could be obtained by dissolution of the aluminum substrate and anodic oxide...
17.
無電解めっきと電気めっきによるセラミックス上への白金厚膜析出 - 菊地, 竜也; 渡辺, 健; 坂入, 正敏; 高橋, 英明; 丸子, 智弘
Thick platinum metal layer was deposited on ceramics using electroless- and electro-plating. The ceramics, which consist of ZrO2, Al2O3, SiO2, Na2O, and other oxides, were etched in HF solution, and then immersed in a platinum electroless plating solution containing Pt(NH3)2(NO2)2 and N2H4 as a reducting regent. The mass of the ceramics specimen slightly decreased with the electroless plating time and then in creased at a rate depending on temperature, but independent of Pt2+ concentration. Two μm thick platinum layer could be deposited uniformly on ceramics by electroless plating for 14.4ks at 323K. Electroplating of platinum in Pt(NH3)2(NO2)2 solution after electroless...
18.
NOx reduction and NO2 emission characteristics in rich-lean combustion of hydrogen - Shudo, Toshio; Omori, Kento; Hiyama, Osamu
Hydrogen is a clean alternative to conventional hydrocarbon fuels, but it is very important to reduce the nitrogen oxides (NOx) emissions generated by hydrogen combustion. The rich-lean combustion or staged combustion is known to reduce NOx emissions from continuous combustion burners such as gas turbines and boilers, and NOx reduction effects have been demonstrated for hydrocarbon fuels. The authors applied rich-lean combustion to a hydrogen gas turbine and showed its NOx reduction effect in previous research. The present study focused on experimental measurements of NO and NO2 emissions from a co-axial rich-lean burner fueled with hydrogen. The results were
compared with...
19.
Hydroformylation of 1-hexene using polymer-supported rhodium catalysts in supercritical carbon dioxide - Fujita, Shin-Ichiro; Akihara, Shuji; Fujisawa, Shinya; Arai, Masahiko
Hydroformylation of 1-hexene was carried out in supercritical CO2 (scCO2) and in organic solvents (toluene and ethyl acetate) using polymer-supported rhodium catalysts, which were prepared from polystyrene bound triphenylphosphine (TPP) and dicarbonylacetylecetonato rhodium. Preparation variables such as TPP/Rh ratio, time of rhodium precursor fixation on the support and time of syngas pretreatment do not produce significant effects on the reaction. The product distribution slightly changes with CO2 pressure. The conversion increases appreciably as H2 pressure is raised in scCO2 but CO retards the reaction. The influence of H2 pressure in scCO2 is slightly different from that in toluene. Changes of...
20.
Micro-patterning in anodic oxide film on aluminium by laser irradiation - Jha, H.; Kikuchi, T.; Sakairi, M.; Takahashi, H.
Microstructures such as microchannels and microchambers were fabricated on anodic oxide film of aluminium with laser direct patterning technique. The aluminium substrate covered with porous type anodic oxide film was dyed with organic dyes followed by hydrothermal treatment. The coloured and pore sealed film shows much higher absorption then as-formed porous film, that makes possible to pattern various types of microstructures on the film by removing the upper part of the film surface by laser irradiation. Structure of the crystallized hydroxide layer on the surface of the anodic oxide film, formed during pore sealing, as well as the partial removal...
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