45 results on '"Masashi, Kunitake"'
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2. Single Crystallization of Cs4PbBr6 Perovskite from Supersaturated Organic Solutions Optimized Through Solubility Studies
- Author
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Satoshi Watanabe, Taiki Hayashida, Masaru Iwai, Yusuke Inomata, Masashi Kunitake, and Tetsuya Kida
- Subjects
General Chemical Engineering ,General Chemistry - Published
- 2023
- Full Text
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Catalog
3. Preparation of water-dispersible Janus nanosheets from K4Nb6O17·3H2O and their behaviour as a two-dimensional surfactant on air–water and water-toluene interfaces
- Author
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Ryoko Suzuki, Tomoki Nagai, Emika Onitsuka, Naokazu Idota, Masashi Kunitake, Taisei Nishimi, and Yoshiyuki Sugahara
- Subjects
Inorganic Chemistry - Abstract
Water dispersible K4Nb6O17·3H2O-based Janus nanosheets were successfully prepared and exhibited unique behaviour at the water–air interface and at the water–toluene interface.
- Published
- 2022
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4. Study of Gases Permeation in Necklace-Shaped Dimethylsiloxane Polymers Bearing POSS Cages
- Author
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Roman Selyanchyn, Shigenori Fujikawa, Naohiro Katsuta, Kazuya Suwa, and Masashi Kunitake
- Subjects
POSS ,organic–inorganic hybrid ,necklace shaped polymer ,gas separation membrane ,Chemical technology ,TP1-1185 ,Chemical engineering ,TP155-156 - Abstract
The transport of small gases (H2, CO2, N2, O2) through a series of novel membranes based on necklace-shaped inorganic polymers (DMS@POSS), in which a polyhedral oligomeric silsesquioxane (POSS) cage unit and soft chains of oligo-dimethyl siloxane (DMS) were alternately connected, was investigated. The influence of the DMS chain length and crosslinking density of the DMS@POSS on membrane properties were studied. The membranes revealed characteristic structure-property relation towards both glass transition and gases transport. Specifically, clear dependence of properties from the length of DMS units (or overall siloxane content) was revealed. Gas transport properties, when compared to state-of-art polydimethylsiloxane and commercial silicone rubber, demonstrated significantly higher selectivity of DMS@POSS for carbon dioxide (in CO2/N2), hydrogen (in H2/N2) and oxygen (in O2/N2) but lowered permeability, proportional to the amount of POSS in the material. With a precise control over mechanical and thermal properties compared to conventional silicone rubbers, described materials could be considered as materials of choice in niche gas separation or other applications. more...
- Published
- 2019
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5. Construction and Scanning Probe Microscopy Imaging of Two-dimensional Nanomaterials
- Author
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Shinobu Uemura and Masashi Kunitake
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Scanning probe microscopy ,Fabrication ,Molecular level ,010405 organic chemistry ,Chemistry ,technology, industry, and agriculture ,Imaging technology ,Nanotechnology ,General Chemistry ,010402 general chemistry ,01 natural sciences ,0104 chemical sciences ,Nanomaterials - Abstract
Several fabrication technologies for molecular level ultra-thin films, from organic to organic–inorganic hybrids, are introduced using the surface imaging technology of scanning probe microscopy (S... more...
- Published
- 2020
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6. Lipophilic probe behavior in microemulsions evaluated by fluorescence correlation spectroscopy
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Johtaro Yamamoto, Yoshio Suzuki, Yoshikatsu Ogawa, Tomoyuki Kamata, Hinako Hashimoto, Masashi Kunitake, and Dai kato
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Surface-Active Agents ,Spectrometry, Fluorescence ,Vitamin E ,Emulsions ,Hydrophobic and Hydrophilic Interactions ,Analytical Chemistry - Abstract
We evaluated the dispersion and diffusion of fluorescent-labeled lipophilic vitamin E (VE) in microemulsions (MEs) including water-in-oil (W/O) type ME, oil-in-water (O/W) type ME, and bicontinuous ME (BME), using fluorescence correlation spectroscopy (FCS). We prepared a fluorescent ATTO 488 or BODIPY group labeled VE (VE-ATTO or VE-BODIPY). VE-ATTO possesses lipophilic and hydrophilic parts, while VE-BODIPY consists solely of the lipophilic part. The VE-ATTO dissolved in heptane solution as an oil phase appeared hot pink in color due to the solvatochromism effect under room light and almost no fluorescent signal, which was unlike the VE-ATTO dissolved in ME solutions and all the VE-BODIPY solutions (typical fluorescent green color). The FCS measurement proved that VE-BODIPY diffuses faster than VE-ATTO. This is presumably because the "surfactant-like" VE-ATTO is localized and trapped at the micro-water/micro-oil interface of the MEs, while the VE-BODIPY exists in the ME phase and macro-oil phase with good dispersion. These results demonstrate that FCS is a powerful tool for the rapid evaluation of the lipophilic probe behavior in heterogeneous ME solutions. more...
- Published
- 2021
7. Monomolecular covalent honeycomb nanosheets produced by surface-mediated polycondensation between 1,3,5-triamino benzene and benzene-1,3,5-tricarbox aldehyde on Au(111)
- Author
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Adam Z. Stieg, Soichiro Yoshimoto, Ryota Tanoue, Ryusei Haraguchi, Rintaro Higuchi, Masashi Kunitake, Nobuo Kimizuka, Shinobu Uemura, and James K. Gimzewski
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Materials science ,General Engineering ,Bioengineering ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,law.invention ,Adsorption ,Chemical engineering ,law ,Covalent bond ,Network covalent bonding ,Honeycomb ,General Materials Science ,Scanning tunneling microscope ,0210 nano-technology ,Electrode potential ,Electrochemical potential ,Nanosheet - Abstract
Fabrication of a two-dimensional covalent network of honeycomb nanosheets comprising small 1,3,5-triamino benzene and benzene-1,3,5-tricarboxaldehyde aromatic building blocks was conducted on Au(111) in a pH-controlled aqueous solution. In situ scanning tunneling microscopy revealed a large defect-free and homogeneous honeycomb π-conjugated nanosheet at the Au(111)/liquid interface. An electrochemical potential dependence indicated that the nanosheets were the result of thermodynamic self-assembly based not only on the reaction equilibrium but also on the adsorption (partition) equilibrium, which was controlled by the building block surface coverage as a function of electrode potential. more...
- Published
- 2020
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8. Nanocarbon Film Electrodes Can Expand the Possibility of Electroanalysis
- Author
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Dai Kato, Eisuke Kuraya, Osamu Niwa, Ryoji Kurita, Shunsuke Shiba, Kyoko Yoshioka, Tomoyuki Kamata, and Masashi Kunitake
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Materials science ,Electrode ,Nanotechnology ,Analytical Chemistry - Published
- 2018
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9. Janus Nanosheets Derived from K4Nb6O17·3H2O via Regioselective Interlayer Surface Modification
- Author
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Yoshiyuki Sugahara, Ryoko Suzuki, Naokazu Idota, Mitsuhito Sudo, Taisei Nishimi, Megumi Hirano, and Masashi Kunitake
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Crystallography ,Materials science ,Surface modification ,Regioselectivity ,Janus - Published
- 2019
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10. Janus Nanosheets Derived from K4Nb6O17·3H2O via Regioselective Interlayer Surface Modification
- Author
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Ryoko, Suzuki, Mitsuhito, Sudo, Megumi, Hirano, Naokazu, Idota, Masashi, Kunitake, Taisei, Nishimi, and Yoshiyuki, Sugahara
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InformationSystems_INFORMATIONSTORAGEANDRETRIEVAL ,GeneralLiterature_REFERENCE(e.g.,dictionaries,encyclopedias,glossaries) - Published
- 2019
11. Study of Gases Permeation in Necklace-Shaped Dimethylsiloxane Polymers Bearing POSS Cages
- Author
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Shigenori Fujikawa, Kazuya Suwa, Roman Selyanchyn, Masashi Kunitake, and Naohiro Katsuta
- Subjects
Materials science ,necklace shaped polymer, gas separation membrane ,gas separation membrane ,Filtration and Separation ,02 engineering and technology ,010402 general chemistry ,Silicone rubber ,lcsh:Chemical technology ,01 natural sciences ,Article ,organic–inorganic hybrid ,chemistry.chemical_compound ,Silicone ,Chemical Engineering (miscellaneous) ,lcsh:TP1-1185 ,Gas separation ,lcsh:Chemical engineering ,POSS ,chemistry.chemical_classification ,Polydimethylsiloxane ,Process Chemistry and Technology ,lcsh:TP155-156 ,Polymer ,necklace shaped polymer ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Membrane ,chemistry ,Chemical engineering ,Siloxane ,0210 nano-technology ,Glass transition - Abstract
The transport of small gases (H2, CO2, N2, O2) through a series of novel membranes based on necklace-shaped inorganic polymers (DMS@POSS), in which a polyhedral oligomeric silsesquioxane (POSS) cage unit and soft chains of oligo-dimethyl siloxane (DMS) were alternately connected, was investigated. The influence of the DMS chain length and crosslinking density of the DMS@POSS on membrane properties were studied. The membranes revealed characteristic structure-property relation towards both glass transition and gases transport. Specifically, clear dependence of properties from the length of DMS units (or overall siloxane content) was revealed. Gas transport properties, when compared to state-of-art polydimethylsiloxane and commercial silicone rubber, demonstrated significantly higher selectivity of DMS@POSS for carbon dioxide (in CO2/N2), hydrogen (in H2/N2) and oxygen (in O2/N2) but lowered permeability, proportional to the amount of POSS in the material. With a precise control over mechanical and thermal properties compared to conventional silicone rubbers, described materials could be considered as materials of choice in niche gas separation or other applications. more...
- Published
- 2019
12. Direct electrochemical hydrogenation of toluene at Pt electrodes in a microemulsion electrolyte solution
- Author
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Masashi Kunitake and Mitsuru Wakisaka
- Subjects
Inorganic chemistry ,02 engineering and technology ,Electrolyte ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Electrochemistry ,01 natural sciences ,Toluene ,0104 chemical sciences ,lcsh:Chemistry ,chemistry.chemical_compound ,chemistry ,lcsh:Industrial electrochemistry ,lcsh:QD1-999 ,Hydrogenolysis ,Electrode ,Microemulsion ,Methylcyclohexane ,0210 nano-technology ,Faraday efficiency ,lcsh:TP250-261 - Abstract
In the present study, we demonstrated a new concept for the direct electrochemical hydrogenation of toluene using an acidic microemulsion electrolyte with active Pt electrodes to pave the way for efficient methylcyclohexane mass production. We have achieved a Faradaic efficiency of 80% for the toluene/methylcyclohexane conversion at a Pt black electrode, under galvanostatic conditions and in a one-compartment cell. The reaction rate and selectivity of the toluene reduction were found to depend strongly on the surface structure of the Pt electrodes. Keywords: Organic hydride, Hydrogenation, Microemulsion, Pt electrode, Surface-sensitive reaction, Hydrogenolysis more...
- Published
- 2016
13. Dynamic Soft Templating of Monolithic Au Thin Film Electrodeposited from Bicontinuous Microemulsion
- Author
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Masanobu Matsuguchi, Shunsuke Shiba, Masashi Kunitake, Dai Kato, Shoei Hirabayashi, and Osamu Niwa
- Subjects
Materials science ,Chemical engineering ,Microemulsion ,Thin film - Abstract
Electrochemical deposition has been the preferred method to use for the soft templating of nanoporous metal thin film because of its low-temperature metallization processes, which prevent damage to the structures not only of soft templates, including self-assembled surfactants or copolymers, but also of the formed nanoporous metals. Recently developed soft-templating methods are based on the replication of highly ordered micelle assemblies composed of surfactants or copolymers. However, it is still difficult to achieve wide size control over 100 nanometers by soft templating, though such control is necessary for electrocatalytic or biosensing applications. We report on the fabrication of monolithic nanoporous gold (Au) thin films by electrodeposition in bicontinuous microemulsion (BME) as a dynamic soft template (Figure (a)). Au electrodeposition occurs only at the aqueous phase of BME, which has intertwined nanometer-ordered three-dimensional networks composed of aqueous and oil solution channels compartmentalized by surfactants and cosurfactants. The thermodynamically stable BME can be formed simply by “mixing” together of the components, and the solution/solution structure of BME could be controlled simply by changing the BME composition. We prepared three kinds of BME solutions, including water-rich BME (water/oil ratio: 66/34), oil-rich BME (33/67), and equally mixed BME (69/31), by mixing 5.00 mL of 1 M hydrochloric acid solution containing 50 mM tetrachloroaurate(III), 5.00 mL cyclohexane, 0.40 g sodium dodecyl sulfate (SDS), and different volumes of 2-methyl-2-butanol (470, 590, and 510 μL, respectively) as cosurfactants. Figure (b-d’) shows the top surface and cross-sectional FE-SEM images of the resultant gold thin film electrodeposited onto sputtered Au film at -0.30 V vs. Ag/AgCl for 300 sec in (a) oil-rich BME, (b) equally mixed BME, and (c) water-rich BME, respectively. The resultant Au films each had a unique monolithic nanostructure grown vertically to the electrode surface. The characteristic ligament diameters of these films increased from 40 to 200 nm as the aqueous solution content increased. These results clearly indicate that BME no doubt behaved as a soft template and successfully demonstrate that structural control can be easily achieved by changing the BME solution/solution structure. In the case of equally mixed BME, we also confirmed that the ligament axial length was controllable between 180 and 650 nm by changing the electrodeposition time from 200 to 400 s. The cross-sectional observation of all the films revealed that there were no side pores even though BME had a reticulated solution structure on the order of 100 nm or less. This indicates that monolithic BME structures changed continuously during electrodeposition depending on the film surface morphology and acted as dynamic soft templates. We conducted voltammetric experiments to assess surface characteristics such as electrochemically active surface area (ECSA), exposed facets, and electrocatalytic activity. The apparent electrode area of each Au film was defined by putting insulating tape with a 2-mm-diameter hole on the electrode surface. The linear sweep voltammetry after forming a fully oxidized surface in 0.5 M H2SO4 solution revealed that the ECSA of the monolithic nanoporous Au film electrodeposited in equally mixed BME for 300 s was 4.2 times greater than that with the sputtered Au film (before electrodeposition). The cyclic voltammetry in the same solution revealed that the oxidation potential of the main peak current of the monolithic nanoporous Au thin film was lower (+1.08 V vs. Ag/AgCl) than that of sputtered Au thin film (1.29 V). These results indicate that the existence of well-exposed {100} facets and/or dominant step/kink sites at the monolithic nanoporous Au thin film probably derived from vertically grown, highly curved nanostructures. As a test reaction, the methanol oxidation reaction (MOR) was used to investigate the electrocatalytic performance of electrodeposited nanoporous Au films. The cyclic voltammetry obtained in the 0.5 M KOH aqueous solution in the absence and presence of 1 M methanol resulted in a 1.9 times larger peak top current (446 μA cm-2 app) at the monolithic nanoporous Au film than that of sputtered Au film due to high ECSA. Interestingly, the onset potential of MOR at the monolithic nanoporous Au film was -0.58 V, which is 0.20 V more negative than that at the sputtered Au film; this might derive from the {100} facets and/or the step/kink structure of the nanoporous Au film. Figure 1 more...
- Published
- 2020
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14. Two-wavelength infrared responsive hydrogel actuators containing rare-earth photothermal conversion particles
- Author
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Masashi Kunitake, Satoshi Watanabe, and Hiroshi Era
- Subjects
Phase transition ,Multidisciplinary ,Materials science ,genetic structures ,Infrared ,lcsh:R ,lcsh:Medicine ,02 engineering and technology ,Bending ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Rod ,Article ,0104 chemical sciences ,Wavelength ,Adsorption ,Volume (thermodynamics) ,lcsh:Q ,Irradiation ,sense organs ,Composite material ,lcsh:Science ,0210 nano-technology - Abstract
Two-wavelength infrared responsive soft actuators composed of rare-earth-oxide particles composited in a thermoresponsive hydrogel have been constructed. Because Nd2O3 and Yb2O3 particles possess independent narrow infrared adsorption at 808 and 980 nm, respectively, the vicinity of the particles in the gel can be individually heated by irradiation at each adsorption wavelength, inducing a local volume phase transition. The wavelength-selective volume phase transition can be controlled based on the combination of the particles incorporated in the gels and the wavelength of the irradiation laser at the optimized water temperature. Only the alternatively correct combinations successfully induced selective local clouding at the irradiation spots in the gel sheets. The original transparency of the gel was immediately recovered by turning off the light. Furthermore, rod-shaped block gels with Nd2O3 and Yb2O3 particles separately arranged on the left and right sides at the bottom of the rods were prepared to demonstrate wavelength-selective bending motion. The correct light combination caused reversible bending motion of only the side of the rod gel with the corresponding adsorbed particles. more...
- Published
- 2018
15. Self-assembled π-conjugated macromolecular architectures — A soft solution process based on Schiff base coupling
- Author
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Ryota Tanoue, Rintaro Higuchi, Shinobu Uemura, and Masashi Kunitake
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Organic electronics ,chemistry.chemical_classification ,Schiff base ,Polymers and Plastics ,Supramolecular chemistry ,Nanotechnology ,Surfaces and Interfaces ,Polymer ,chemistry.chemical_compound ,Colloid and Surface Chemistry ,chemistry ,Polymerization ,Covalent bond ,Molecule ,Physical and Theoretical Chemistry ,Macromolecule - Abstract
Two-dimensional supramolecular covalent macromolecular architectures were visualized directly by in-situ scanning tunneling microcopy and colorful π-conjugated nanofilms with unique mesostructures formed spontaneously on hydrophobic substrates from aqueous solutions in the presence of simple aromatic building block molecules under ambient conditions. We thus report the results of surface-mediated polycondensation and chemical liquid deposition. The Schiff base coupling reaction applied for this soft solution process is a dynamic reversible covalent coupling reaction that can be managed by careful changes in solution conditions based on ‘adsorption’ and ‘polymerization’ equilibria. This low-cost and eco-friendly ‘bottom-up’ method allows great diversity in terms of the design of primary polymeric chemical structures by the selection of building blocks without the need to consider the solubility of the polymer. This paves the way to a true ‘bottom-up’ assembly of a vast array of solid-supported, designer supramolecular nanoarchitectures with potential use as functional materials for next-generation organic electronics. more...
- Published
- 2014
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16. Positional selectivity of reversible azomethine condensation reactions at solid/liquid interfaces leading to supramolecule formation
- Author
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Shinobu Uemura, Ryota Tanoue, Kiryu Ikebe, James K. Gimzewski, Nobuo Kimizuka, Rintaro Higuchi, Masashi Kunitake, and Adam Z. Stieg
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Schiff base ,General Chemical Engineering ,Condensation ,Photochemistry ,Condensation reaction ,Porphyrin ,Coupling reaction ,Analytical Chemistry ,chemistry.chemical_compound ,Crystallography ,Nanomesh ,chemistry ,Electrochemistry ,Molecule ,Selectivity - Abstract
We used in situ scanning tunneling microscopy to investigate the formation of two-dimensional supramolecules by means of reversible azomethine condensation reactions between aqueous 5,10,15,20-tetrakis(4-aminophenyl)porphyrin (TAPP) and terephthaldicarboxaldehyde (TPA) or benzaldehyde (BA) at the solid/liquid interface of an iodine-modified Au(1 1 1) surface. A nanomesh and a close-packed array were formed by the reaction of TAPP with the dicarboxaldehyde. Formation of these structures was driven by Schiff base (azomethine) bonding and simultaneous self-assembly controlled by adsorption and condensation equilibria. Surface cross coupling between TAPP and the monocarboxaldehyde (BA) formed highly ordered adlayers consisting solely of TAPP symmetrically disubstituted with two BA molecules attached at diagonally opposite corners. The position selectivity was achieved through simultaneous coupling reaction equilibria and the thermodynamic self-assembly. more...
- Published
- 2014
- Full Text
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17. Monomolecular covalent honeycomb nanosheets produced by surface-mediated polycondensation between 1,3,5-triamino benzene and benzene- 1,3,5-tricarbox aldehyde on Au(111).
- Author
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Masashi Kunitake, Ryota Tanoue, Rintaro Higuchi, Soichiro Yoshimoto, Ryusei Haraguchi, Shinobu Uemura, Nobuo Kimizuka, Stieg, Adam Z., and Gimzewski, James K.
- Published
- 2020
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18. Aqueous Dispersion and Temperature Induced Reversible Fluorescence Properties of 1-Pyrenecarboxaldehyde
- Author
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Masashi Kunitake and Ashaduzzaman
- Subjects
Solvent ,chemistry.chemical_compound ,Aqueous solution ,Monomer ,chemistry ,Analytical chemistry ,1-pyrenecarboxaldehyde ,Aqueous dispersion ,Photochemistry ,Excimer ,Temperature induced ,Fluorescence - Abstract
The fluorescence intensities for various vibronic fine structures in the 1-pyrenecarboxaldehyde (PyCHO) fluorescence show strong environment dependence. In aqueous solvent, the distribution of dye is highly depended on its concentration labels and varies from excimer to monomeric state. UV-Vis Spectroscopic analysis could not able to detect dye below 10-7M concentration, whereas a new monomeric peak at 342 nm was observed after heating and cooling treatment at above the concentration. At 10-8M concentration, only monomeric distribution of 1-PyCHO reveals a strong temperature (20-50 °C) induced reversible perturbation of the vibronic band intensities. This suggests the operation of some specific solute-solvent dipole-dipole interaction mechanism strongly influenced by heating. more...
- Published
- 2013
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19. Surface Initiated ATRP: Synthesis and Characterization of Functional Polymers Grafted on Modified Cellulose Beads
- Author
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Ashaduzzaman, Masashi Kunitake, Kei Ishikura, and Masayo Sakata
- Subjects
chemistry.chemical_classification ,chemistry.chemical_compound ,Monomer ,Aqueous solution ,chemistry ,Atom-transfer radical-polymerization ,Sodium hydroxide ,Polymer chemistry ,Surface modification ,Polymer ,Cellulose ,Functional polymers - Abstract
Atom transfer radical polymerization (ATRP) was employed to synthesize novel polymer particles. The surface of porous polymeric cellulose beads was modified by sodium hydroxide, 2-chloromethyloxirane, ethylenediamine and 2-bromo-2-methylpropionyl bromide successively in order to activate the beads surface so that it can play an important role as an initiator for ATRP reaction. ATRP on the modified cellulose beads surface was carried out with styrene and sodium p-styrenesulphonate monomers in the presence of non aqueous and aqueous phases respectively. The polymer products on the substrate surface were characterized by elemental analysis (EA), attenuated total reflectance-infrared (ATR-IR) spectroscopy and carbon13 – nuclear magnetic resonance (13C-NMR). more...
- Published
- 2013
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20. Investigation of Click Reaction at an Oil-Water Interface Using Hydrophobic and Hydrophilic Polymers
- Author
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Shu Hei Kai, Masashi Kunitake, and Ashaduzzaman
- Subjects
chemistry.chemical_classification ,chemistry.chemical_compound ,Sulfonate ,chemistry ,Polymer chemistry ,Click chemistry ,Copolymer ,Aqueous two-phase system ,Polymer ,Polystyrene ,Methacrylate ,Styrene - Abstract
Cu(I)-catalyzed Huisgen click reactions between lipophilic polymer (tri-arm azidofunctionalized polystyrene) and hydrophilic polymer (copolymer of styrene sulfonate sodium and propargyl methacrylate) were investigated and hollow capsules, consisting of composite polymer nanofilms were obtained in chloroform-water biphasic solution. Since the lipophilic polymer, or hydrophilic polymer and copper catalyst were present in the oil or aqueous phase, respectively, the cross-linking reaction proceeded only at the phase interface. The combination of lipophilic and hydrophilic polymers produced hollow capsules consisting of nanofilms with lipophilic core and hydrophilic shell. more...
- Published
- 2013
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21. Thixotropic interparticle interaction between silica and nonionic polymer particles prepared by static dispersion polymerization
- Author
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Asumi Sei, Shintaro Kawano, and Masashi Kunitake
- Subjects
Dispersion polymerization ,Materials science ,Static dispersion polymerization ,Polymers and Plastics ,Organic Chemistry ,Dispersity ,Radical polymerization ,Methacrylate ,Polystyrene particles ,Silica particles ,chemistry.chemical_compound ,Polymerization ,Chemical engineering ,chemistry ,431.9 ,Polymer chemistry ,Dispersion stability ,Materials Chemistry ,Methyl methacrylate ,Dispersion (chemistry) - Abstract
Static dispersion polymerization of styrene, methyl methacrylate, ethyl methacrylate, butyl methacrylate and benzyl methacrylate, initiated by a lipophilic initiator in an aqueous dispersion with unmodified silica particles was investigated. Polymerization of styrene gave a mixed dispersion of silica and monodisperse polystyrene (PS) particles, which was extremely stable compared with the aqueous dispersion of silica particles. The enhanced dispersion stability is due to a thixotropic effect based on weak attractive interparticle interactions between silica and PS particles in aqueous dispersion. An aggregate in which silica particles are surrounded by the smaller PS particles is formed and inhibits flocculation of silica particles, thus giving enhanced dispersion stability. The results of similar static polymerization reactions with methacrylate analogs indicate that hydrogen bonds between benzene ring and hydroxy groups on the silica surface, and not electrostatic interaction derived from initiator residues, are the origin of weak interaction for thixotropic aggregation. more...
- Published
- 2011
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22. Effect of Co-adsorption of Ascorbic Acid and Boric Acid Compared to Absorption of Each Single Component on Long-term Oxidation-resistivity for the Negative Active Materials of Lead-acid Batteries
- Author
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Katsuhiko Nishiyama, Takateru Yamamuro, Takashi Araki, Masashi Kunitake, and Nagayoshi Miyanari
- Subjects
Boric acid ,chemistry.chemical_compound ,Adsorption ,chemistry ,Inorganic chemistry ,Electrode ,Electrochemistry ,Oxide ,Electron microprobe ,Absorption (chemistry) ,Mass spectrometry ,Ascorbic acid - Abstract
A simple and useful technique for preparing an oxidation-resistant film on a Pb electrode is reported herein. A Pb electrode was dipped into a mixed solution containing 1% ascorbic acid and 5% boric acid at 40°C and then air-dried. The Pb electrode was coated with a film on its surface to protect it from oxidation. After three months, the oxide layers on the Pb plate were analyzed by treatment with pure ascorbic acid or boric acid. An oxidized layer was not observed on the plate treated with the mixed solution of ascorbic acid and boric acid; this was confirmed using an electron probe micro analyzer (EPMA). To further analyze the effect of co-absorption, the interaction between ascorbic acid and boric acid in solution was evaluated using a UV-visible spectrometer, and mixed solid samples were analyzed using FT-IR spectrometry. more...
- Published
- 2011
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23. モノズクリ カラ カンガエル クラシ ト カガク
- Author
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Masashi, Kunitake
- Subjects
377.15 - Published
- 2014
24. Sparsely-distributed silica/PMMA composite particles prepared by static polymerization in aqueous silica dispersion
- Author
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Asumi Sei, Shintaro Kawano, and Masashi Kunitake
- Subjects
Materials science ,Static dispersion polymerization ,Surface Properties ,Composite number ,Silica particles Poly(methyl methacrylate) ,Biomaterials ,chemistry.chemical_compound ,431.8 ,Colloid and Surface Chemistry ,Adsorption ,Polymer chemistry ,Polymethyl Methacrylate ,Organic–inorganic composite materials ,Methyl methacrylate ,Particle Size ,Fumed silica ,Dispersion polymerization ,Water ,Silicon Dioxide ,Poly(methyl methacrylate) ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry ,Polymerization ,Chemical engineering ,visual_art ,visual_art.visual_art_medium ,Dispersion (chemistry) - Abstract
Silica/poly(methyl methacrylate) (PMMA) composite particles, in which silica particles are sparsely distributed in the surface of PMMA particles, were formed by static dispersion polymerization of methyl methacrylate (MMA) in aqueous dispersions of submicron silica particles. The silica-modified PMMA particles were constructed via Pickering emulsion-like silica/PMMA aggregation based on weak interaction between PMMA and silica. The morphology of the composite particles is governed by the adsorption/partition equilibrium of PMMA with the silica surface. more...
- Published
- 2010
25. Molecular Dynamics in Two-Dimensional Supramolecular Systems Observed by STM
- Author
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Neval Yilmaz, Masashi Kunitake, Ryota Tanoue, Shinobu Uemura, and Akihiro Ohira
- Subjects
adsorption-induced ,Supramolecular chemistry ,Nanotechnology ,Review ,self-crystallization ,lcsh:Technology ,law.invention ,Molecular dynamics ,law ,Molecular motion ,General Materials Science ,lcsh:Microscopy ,lcsh:QC120-168.85 ,lcsh:QH201-278.5 ,lcsh:T ,Chemistry ,scanning tunneling microscopy (STM) ,Resolution (electron density) ,Intermolecular force ,dynamics ,self-assembly ,lcsh:TA1-2040 ,lcsh:Descriptive and experimental mechanics ,lcsh:Electrical engineering. Electronics. Nuclear engineering ,Self-assembly ,Scanning tunneling microscope ,lcsh:Engineering (General). Civil engineering (General) ,lcsh:TK1-9971 - Abstract
Since the invention of scanning tunneling microscopy (STM), 2D supramolecular architectures have been observed under various experimental conditions. The construction of these architectures arises from the balance between interactions at the medium-solid interface. This review summarizes molecular motion observed in 2D-supramolecular structures on surfaces using nanospace resolution STM. The observation of molecular motion on surfaces provides a visual understanding of intermolecular interactions, which are the major driving force behind supramolecular arrangement. more...
- Published
- 2010
26. Pore-size Controlled and Polycation-immobilized Cellulose Spherical Particles for Removal of Endotoxin
- Author
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Masayo Sakata, Masami Todokoro, and Masashi Kunitake
- Subjects
Pore size ,chemistry.chemical_compound ,Materials science ,Chromatography ,Polymers and Plastics ,chemistry ,Materials Science (miscellaneous) ,Chemical Engineering (miscellaneous) ,Cellulose ,General Environmental Science - Abstract
セルロース微粒子を基材とし,これに種々のポリカチオンを化学修飾した高分子球状微粒子を調製した.得られた種々のポリカチオン固定化セルロース粒子をエンドトキシン(LPS)吸着剤として用い,バッチ法により LPS 水溶液からの LPS 吸着除去を試みた.その結果,すべての粒子の LPS 吸着能は,粒子の細孔径(糖の排除限界分子;Mlim)の増大とともに著しく増大し,吸着時の緩衝液のイオン強度の上昇とともに低下した.種々の吸着剤のタンパク質溶液からの LPS 選択除去能をカラム法により評価した結果,ポリ(e-リジン)固定化セルロース粒子は pH 7,イオン強度 μ=0.17 の条件下で,アルブミンを吸着することなく,LPS を吸着除去できた.吸着処理後の溶液中の LPS 残存濃度は 10 pg/mL 以下で,タンパク質回収率は 98%であった.これらの結果から,同粒子はタンパク質水溶液からの LPS 吸着除去剤として大いに期待できることがわかった. more...
- Published
- 2007
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27. Continuous Porous Poly(N-isopropylacrylamide) Gels Prepared from a Bicontinuous Microemulsion
- Author
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Kouhei Sakata, Shintaro Kawano, Shinobu Uemura, Shun Taguchi, Taisei Nishimi, and Masashi Kunitake
- Subjects
chemistry.chemical_compound ,chemistry ,Chemical engineering ,Radical polymerization ,technology, industry, and agriculture ,Poly(N-isopropylacrylamide) ,Microemulsion ,General Chemistry ,Porosity ,Toluene - Abstract
Continuous porous poly(N-isopropylacrylamide) (pNIPAM) gels were prepared by radical polymerization in a bicontinuous microemulsion (BME) consisting of saline and toluene microphases. The BME gels ... more...
- Published
- 2014
- Full Text
- View/download PDF
28. Two Dimensional Molecular Arrangements Prepared by Adsorption-induced Self-organization
- Author
-
Masashi Kunitake
- Subjects
Surface diffusion ,Adsorption ,Aqueous solution ,Chemical physics ,Chemistry ,Computational chemistry ,Desorption ,Intermolecular force ,Molecule ,Substrate (chemistry) ,Electrode potential - Abstract
Adsorption-induced self-organization is a new concept for “wet process” techniques for preparing highly ordered molecular adlayers by spontaneous adsorption in aqueous solution. The essential step is a thermodynamically controlled “mild” adsorption, which makes possible rapid surface diffusion and adsorption/desorption equilibrium. 2D-supramolecular structures of various molecules were possible to be constructed by choosing a proper substrate and an electrode potential, that is controlled adsorption STM visualization of highly ordered molecules provides fundamental data on intermolecular interactions. more...
- Published
- 2004
- Full Text
- View/download PDF
29. The design of polymer microcarrier surfaces for enhanced cell growth
- Author
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Chuichi Hirayama, Toshihiko Sakurai, Dai Kato, Masahiko Takeuchi, Masayo Sakata, Shin Ichi Furukawa, Hiroshi Mizokami, and Masashi Kunitake
- Subjects
Anions ,Time Factors ,Materials science ,Polymers ,Cell Culture Techniques ,Biophysics ,Bioengineering ,Cell Line ,Biomaterials ,Mice ,Reaction rate constant ,Cations ,medicine ,Animals ,Organic chemistry ,Microscopy, Phase-Contrast ,Amino Acids ,Fibroblast ,Alkyl ,chemistry.chemical_classification ,Cell growth ,Temperature ,Cationic polymerization ,Microcarrier ,Polymer ,Fibroblasts ,Hydrogen-Ion Concentration ,Kinetics ,medicine.anatomical_structure ,Models, Chemical ,Polyglutamic Acid ,chemistry ,Mechanics of Materials ,Ceramics and Composites ,Particle ,Cell Division - Abstract
A variety of neutral and cationic polymers based on polyamino acids were prepared and investigated as microcarriers for cell attachment and growth. Among neutral polymer particles including the alkylated poly(gamma-methyl L-glutamate) (PG) particles, in which the hydrophobicity changes as a function of the length of the alkyl groups, and hydroxy terminal PG particles, the PG particle with the longest alkyl chain (PG-C12) demonstrated the highest cell attachment rate and highest rate of cell growth. Moreover, the introduction of hydroxyl groups (PG-OH) led to a deterioration of cell growth. Cell growth on cationic particles having primary amino groups was drastically dependent upon the anion exchange capacity (AEC). A higher AEC for aminated PG microcarriers inhibited cell growth. In contrast, a higher AEC for cross-linked poly( epsilon -lysine) (PL) microcarriers facilitated cell growth. Cell growth on cationic particles clearly showed a good correlation with the pK(a,app) of the microcarriers, but not with their AEC. The particles with low and high pK(a) values possessed toxically acidic and basic pH microenvironments near the surface, respectively. These microenvironments had cytotoxic effects. On the other hand, no correlation between attachment rate constants and high cell growth was observed. The aminated particles, in which pK(a) were controlled at neutral pH, and PG-C12 produced obviously higher cell growth than did a commercially available microcarrier. more...
- Published
- 2003
- Full Text
- View/download PDF
30. [Untitled]
- Author
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Kouchi Matsumoto, Masao Miyazakia, Masashi Kunitake, Chuichi Hirayama, and Masayo Sakata
- Subjects
chemistry.chemical_classification ,Salmonella ,Chromatography ,Lipopolysaccharide ,medicine.diagnostic_test ,Ethyleneimine ,Bioengineering ,General Medicine ,medicine.disease_cause ,Applied Microbiology and Biotechnology ,Rapid detection ,Polyester ,chemistry.chemical_compound ,Cartridge ,Enzyme ,chemistry ,Immunoassay ,parasitic diseases ,Polymer chemistry ,medicine ,Biotechnology - Abstract
Utilizing the rapidity in capturing Salmonella lipopolysaccharide (LPS) and the macroporous nature of poly(ethyleneimine) immobilized polyester cloth (PEI-cloth), a PEI-cloth disk set in a Swinnex cartridge joined at both ends with 10 ml plastic syringes was repeatedly passed through with an LPS sample in large volumes. The captured LPS on the disk were detected at up to 1 pg, which is equivalent to the amount produced of 16 cells, by cloth enzyme immunoassay. more...
- Published
- 2002
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31. [Untitled]
- Author
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Masashi KUNITAKE and Akihiro OHIRA
- Subjects
General Chemical Engineering - Published
- 2002
- Full Text
- View/download PDF
32. Formation of the ‘nanotube’ structure of β-cyclodextrin on Au(III) surfaces induced by potential controlled adsorption
- Author
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Chuichi Hirayama, Masashi Kunitake, Isao Taniguchi, Takahiro Ishizaki, Akihiro Ohira, and Masayo Sakata
- Subjects
chemistry.chemical_classification ,Nanotube ,Polymer ,Sodium perchlorate ,law.invention ,chemistry.chemical_compound ,Crystallography ,Colloid and Surface Chemistry ,Adsorption ,chemistry ,law ,Desorption ,Molecule ,Scanning tunneling microscope ,Electrode potential - Abstract
The self-organization of β-cyclodextrin (β-CyD) into a ‘nanotube’ structure, similar to that of CyD-polyrotaxane, was found to be induced by potential controlled adsorption on Au(III) surfaces in sodium perchlorate solution without a threaded polymer. In-situ scanning tunneling microscopy (STM) revealed that the cavities of β-CyD faced sideward not upward in the tubes. This ordered structure can form only under conditions where the potential is controlled (−0.45 V to −0.25 V vs. SCE). β-CyD molecules were in a disordered state on bare Au(III) surfaces without potential control (+0.00 V vs. SCE). In addition, the desorption of β-CyD from Au surfaces was observed at a negative potential of less than −0.60 V. In the range −0.45 to −0.25 V, β-CyD molecules formed ordered arrays on Au(111) surfaces. Furthermore, the discontinuity of potential control led to disordered phases and the destruction of the ‘tube’ structure. This indicates that by controlling the electrode potential a delicate balance of various interactions can be achieved, resulting in the self-organization of molecules on the surface. more...
- Published
- 2000
- Full Text
- View/download PDF
33. Two-Dimensional Highly Ordered Molecular Layers Prepared by Adsorption-Induced Self-Organization
- Author
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Masashi Kunitake
- Subjects
Surface diffusion ,Crystallography ,Aqueous solution ,Adsorption ,Chemical engineering ,Chemistry ,Desorption ,Intermolecular force ,Substrate (chemistry) ,Molecule ,Electrode potential - Abstract
Adsorption-induced self-organization is a new concept for “wet process” techniques for preparing highly ordered molecular adlayers by spontenious adsorption in aqueous solution. The essential step is a controlled “mild” adsorption, which makes possible rapid surface diffusion and adsorption/desorption equilibrium. To conduct “mild” adsorption, the choice of substrate and setting of electrode potential are most possible. STM visualization of highly ordered molecules provides fundamental data on intermolecular interactions. more...
- Published
- 2000
- Full Text
- View/download PDF
34. Selective Assay for LPS with Polylysine-Immobilized Cellulose Beads and Limulus Amebocyte Lysate
- Author
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Masashi Kunitake, Yuriko Fukuma, Masami Todokoro, and Masayo Sakata
- Subjects
Chromatography ,Lipopolysaccharide ,Bioengineering ,Surfaces and Interfaces ,Condensed Matter Physics ,Surfaces, Coatings and Films ,chemistry.chemical_compound ,Adsorption ,Adsorption kinetics ,chemistry ,Mechanics of Materials ,Limulus amebocyte lysate ,Reagent ,Polylysine ,Centrifugation ,Cellulose ,Biotechnology - Abstract
We developed a endotoxin (lipopolysaccharide; LPS) assay using poly(e-lysine)-immobilized cellulose beads and Limulus amebocyte lysate (LAL). This method is composed of two steps. First, endotoxins are selectively adsorbed on the beads in protein solutions, and then the adsorbed endotoxins are separated from the compound such as protein by centrifugation. Second, the endotoxins adsorbed on the beads are directly reacted with the LAL reagent by tubidimetric time assay using Toxinometer ET-2000 (Wako). This assay method could be used widely as a means of assaying LPS in solutions containing LAL-inhibiting or enhancing substances, such as protein. [DOI: 10.1380/ejssnt.2009.747] more...
- Published
- 2009
- Full Text
- View/download PDF
35. Visualized Polymers. Patterns Formed by Polymeric Systems. I. Adsorption-Induced Two-Dimensional Self-Organization
- Author
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Akihiro Ohira, Chuichi Hirayama, Masashi Kunitake, Masayo Sakata, and Shinobu Uemura
- Subjects
chemistry.chemical_classification ,Nanotube ,Materials science ,Adsorption ,Fullerene ,Polymers and Plastics ,Cyclodextrin ,chemistry ,Materials Science (miscellaneous) ,Chemical Engineering (miscellaneous) ,Nanotechnology ,Epitaxy ,General Environmental Science - Published
- 1999
- Full Text
- View/download PDF
36. Thermodynamic Self Assembly of Two-Dimensional pi-Conjugated Metal-Porphyrin Covalent Organic Frameworks by On-Site Equilibrium Polymerization
- Author
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Rintaro Higuchi, James K. Gimzewski, Shinobu Uemura, Adam Z. Stieg, Masashi Kunitake, Nobuo Kimizuka, Ryota Tanoue, and Kiryu Ikebe
- Subjects
Condensed Matter - Materials Science ,Aqueous solution ,Materials science ,Biomedical Engineering ,Materials Science (cond-mat.mtrl-sci) ,FOS: Physical sciences ,Bioengineering ,General Chemistry ,Conjugated system ,Condensed Matter Physics ,Porphyrin ,law.invention ,chemistry.chemical_compound ,Adsorption ,chemistry ,Polymerization ,Covalent bond ,law ,Polymer chemistry ,General Materials Science ,Self-assembly ,Scanning tunneling microscope - Abstract
Two dimensional pi conjugated metal porphyrin covalent organic frameworks were produced in aqueous solution on an iodine-modified Au(111) surface by on site azomethine coupling of Fe(III) 5,10,15,20 tetrakis(4 aminophenyl)porphyrin (FeTAPP) with terephthal dicarboxaldehyde and investigated in detail using in-situ scanning tunneling microscopy. Mixed covalent organic porphyrin frameworks consisting of FeTAPP and metal-free TAPP (H2TAPP) were prepared through simultaneous adsorption in a mixed solution as well as partial replacement of FeTAPP by H2TAPP in an as prepared metal porphyrin framework. In the mixed framework, the relative distribution of FeTAPP to H2TAPP was not random and revealed a preference for homo-connection rather than heteroconnection. The construction of substrate-supported, pi conjugated covalent frameworks from multiple building blocks, including metal centers, will be of significant utility in the design of functional molecular nanoarchitectures., 7 pages, 5 figures more...
- Published
- 2013
37. Structural Effects on Reaction Rate and Selectivity for Direct Electrochemical Hydrogenation of Aromatic Hydrocarbons at Pt Electrocatalysts
- Author
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Mitsuru Wakisaka and Masashi Kunitake
- Abstract
Organic chemical hydrides have been attracting considerable attention as hydrogen carriers.1-3 From the viewpoints of the total energy conversion efficiency, direct electrochemical hydrogenation of aromatic hydrocarbons to obtain hydrides is preferable to the conventional multistep reaction process consisting of water electrolysis and gas-solid catalytic hydrogenation with the produced hydrogen. So far, several groups have reported the direct electrochemical hydrogenation of aromatic hydrocarbons at Hg, Ni or Pt electrocatalysts in quaternary ammonium ion supporting electrolytes,4-6 at Raney Ni electrocatalysts in ethylene glycol solutions,7 at non-catalyzed carbon electrodes in bi-continuous microemulsions,8,9 or using membrane electrode assemblies (MEAs) consisting of Pt or PtRu nanoparticle electrocatalysts and proton or anion exchange membranes.10-12 Very recently, we have demonstrated the direct electrochemical hydrogenation of toluene at Pt electrodes in a microemulsion electrolyte solution.13 We have achieved a Faradaic efficiency of 80% for the toluene/methylcyclohexane conversion at a Pt black electrode with a roughness factor (RF) of 360 even under galvanostatic conditions and in a one-compartment cell filled with the Winsor III type microemulsion, as shown in Figure 1. However, the reaction rate and selectivity of the toluene reduction were found to depend strongly on the surface structure of the Pt electrodes in the microemulsion, as shown by steady-state polarization curves at the Pt black electrode and a mirror-finished Pt electrode (RF = 2) in Figure 2. Interestingly, cyclohexane rather than methylcyclohexane was found as the predominant product at the mirror-finished Pt electrode. The formation of cyclohexane can be ascribed to the further reduction (hydrogenolysis) of the produced methylcyclohexane, yielding methane. Similar phenomenon, splitting of the methyl group, has been previously reported by Heitbaum and co-workers in their study of toluene reduction at a Pt sputtered on a Teflon membrane (RF = 8) in a 0.5 M H2SO4 solution using differential electrochemical mass spectroscopy (DEMS).14 In the meeting, we will present the latest results of direct electrochemical hydrogenation of other aromatic hydrocarbons such as benzene, xylene and naphthalene, and will discuss the structural effects on the reaction rate and selectivity. This research was supported by Japan Science and Technology Agency, PRESTO. E. Newson, TH. Haueter, P. Hottinger, F. Von Roth, G. W. H. Scherer, and TH. H. Schucan, Int. J. Hydrogen Energy, 23, 905 (1998). Y. Okada, E. Sasaki, E. Watanabe, S. Hyodo, and H. Nishijima, Int. J. Hydrogen Energy, 31, 1348 (2006). R. B. Biniwale, S. Rayalu, S. Devotta, and M. Ichikawa, Int. J. Hydrogen Energy, 33, 360 (2008). J. P. Coleman and J. H. Wagenknecht, J. Electrochem. Soc., 128, 322 (1981). P. N. Pintauro and J. R. Bontha, J. Appl. Electrochem., 21, 799 (1994). E. G. Palffy, P. Starzewski, A. Labani, and A. Fontana, J. Appl. Electrochem., 24, 337 (1994). D. Robin, M. Comtois, A. Martel, R. Lemieux, A. K. Cheong, G. Belot, and Jean Lessard, Can. J. Chem., 68, 1218 (1990). M. O. Iwunze, A. Sucheta, and J. F. Rusling, Anal. Chem., 62, 644 (1990). H. Carrero, J. Gao, J. F. Rusling, C.-W. Lee, and A. J. Fry, Electrochim. Acta, 45, 503 (1999). P. Wang, T. Minegishi, G. Ma, K. Takanabe, Y. Satou, S. Maekawa, Y. Kobori, J. Kubota, and K. Domen, J. Am. Chem. Soc., 134, 2469 (2012). V. Kalousek, P. Wang, T. Minegishi, T. Hisatomi, K. Nakagawa, S. Oshima, Y. Kobori, J. Kubota, and K. Domen, ChemSusChem, 7, 2690 (2014). S. Mitsushima, Y. Takakuwa, K. Nagasawa, Y. Sawaguchi, Y. Kohno, K. Matsuzawa, Z. Awaludin, A. Kato, and Y. Nishiki, Electrocatalysis, 7, 127 (2016). M. Wakisaka and M. Kunitake, Electrochem. Commun., 64, 5 (2016). J. Zhu, T. Hartung, D. Tegtmeyer, H. Baltruschat, and J. Heitbaum, J. Electroanal. Chem., 244, 273 (1988). Figure 1 more...
- Published
- 2016
- Full Text
- View/download PDF
38. Selective removal of endotoxin from a DNA solution by cross-linked cyclodextrin beads
- Author
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Kana Yoshimura, Masayo Sakata, Masami Todokoro, Itsumi Sakamoto, and Masashi Kunitake
- Subjects
chemistry.chemical_classification ,Lipopolysaccharides ,Chromatography ,Lipopolysaccharide ,Cyclodextrin ,Osmolar Concentration ,beta-Cyclodextrins ,Cationic polymerization ,Polymer ,DNA ,Buffers ,Hydrogen-Ion Concentration ,Microspheres ,Analytical Chemistry ,Solutions ,chemistry.chemical_compound ,Adsorption ,chemistry ,Ionic strength ,lipids (amino acids, peptides, and proteins) ,A-DNA ,gamma-Cyclodextrins - Abstract
The removal of lipopolysaccharide (LPS) from a contaminated DNA solution was achieved using cross-linked cyclodextrin (CyD polymer) beads as LPS adsorbents. The LPS-removing activity of the β- and γ-CyD polymer beads was compared with that of common cationic LPS adsorbents. The γ-CyD polymer beads selectively removed LPS from a DNA solution (50 µg mL(-1), pH 6, ionic strength μ = 0.2) containing natural LPS (15 EU mL(-1)), without the adsorption of DNA. The adsorptions of LPS and DNA were 85% and1%, respectively. more...
- Published
- 2011
39. Limulus amebocyte lysate assay for endotoxins by an adsorption method with polycation-immobilized cellulose beads
- Author
-
Masami Todokoro, Masashi Kunitake, Tomofumi Inoue, and Masayo Sakata
- Subjects
chemistry.chemical_classification ,Lipopolysaccharides ,Chromatography ,Chemistry ,Surface Properties ,Osmolar Concentration ,Microspheres ,Analytical Chemistry ,Suspension (chemistry) ,Amino acid ,chemistry.chemical_compound ,Adsorption ,Limulus amebocyte lysate ,Ionic strength ,Reagent ,Cations ,lipids (amino acids, peptides, and proteins) ,Centrifugation ,Polylysine ,Cellulose ,Limulus Test - Abstract
To assay lipopolysaccharides (LPSs) in solutions containing Limulus amebocyte lysate (LAL)-inhibiting or LAL-enhancing compounds, we developed a selective endotoxin (LPS) assay using poly(epsilon-lysine)-immobilized cellulose beads (PL-Cellufine) and LAL. The PL-Cellufine can adsorb LPSs in a solution containing certain compounds (NaCl, proteins and amino acids) at an ionic strength of mu = 0.05-0.4 at neutral pH. The LPSs adsorbed on the PL-Cellufine were separated from the compounds by centrifugation and then the PL-Cellufine was suspended in LPS-free water. The LPS activities of the suspension are directly assayed by a turbidimetric time assay with the LAL reagent. The accuracy of the adsorption method was high compared with those of common solution methods. As for the common method, the apparent recovery of LPS from the compounds was 40-95%. This suggests that these compounds inhibit the LAL procedure. By contrast, the adsorption method showed good LPS recovery (88-120%) in all cases, without being inhibited or enhanced by the compounds. more...
- Published
- 2010
40. Phase Transition Dependent A. C. Impedance Response of Polymeric Ammonium Chloride Bilayer Films on a Patterned Electrode under a Usual Air Atmosphere
- Author
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Masashi Kunitake, Yoshihisa Yamaguchi, Naotoshi Nakashima, Shin-ichiro Kawahara, and Osamu Manabe
- Subjects
Phase transition ,chemistry.chemical_compound ,Materials science ,Chemical engineering ,chemistry ,Bilayer ,Electrode ,Air atmosphere ,Ammonium chloride ,General Chemistry ,A c impedance - Published
- 1992
- Full Text
- View/download PDF
41. Combination of the quartz crystal microbalance and the electrochemical technique for the characterization of self-assembled monolayers of octadecylmercaptan on gold surfaces
- Author
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Yoshitaka Narikiyo, Osamu Manabe, Masashi Kunitake, and Naotoshi Nakashima
- Subjects
Solvent ,Materials science ,Mechanics of Materials ,Mechanical Engineering ,Monolayer ,Electrode ,Analytical chemistry ,General Materials Science ,Self-assembled monolayer ,Quartz crystal microbalance ,Thin film ,Cyclic voltammetry ,Electrochemistry - Abstract
Quartz crystal microbalance (QCM) technique has been applied to the direct mass measurement of a self-assembled monolayer of octadecylmercaptan (OM) on a gold surface deposited onto a quartz-crystal. Repeated rinsing of the modified electrodes with used solvent was conducted to get self-assembled monolayers of OM. From the resonance frequency change, 2.5 nm molecular occupied area of OM on gold was obtained. The advantage of the combination of QCM and electrochemical methods was emphasized for the characterization of self-assembled monolayers. more...
- Published
- 1995
- Full Text
- View/download PDF
42. Mesostructured Polymer Materials Based on Bicontinuous Microemulsions
- Author
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Masashi Kunitake, Kouhei Sakata, Taisei Nishimi, Masashi Kunitake, Kouhei Sakata, and Taisei Nishimi
- Published
- 2012
- Full Text
- View/download PDF
43. Sophistication and Reconstruction of Environmental-oriented Student Experiments
- Author
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Masashi, Kunitake and Tsuyoshi, Sawada
- Subjects
環境教育 ,student experiment ,学生実験 ,377.15 ,Environmental education - Published
- 2008
44. カ オ トッテ ツイデニ トッキョ モ トッテ オオモウケ
- Author
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Seiko, Sakamoto and Masashi, Kunitake
- Subjects
蚊取りシート ,二酸化炭素 ,377.15 ,開発 - Published
- 2007
45. Coronene-Iodine Coadsorbed Adlayers on Au(111) Surfaces Promoted by Electrochemical Potential Control
- Author
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Masashi Kunitake
- Abstract
not Available.
- Published
- 2006
- Full Text
- View/download PDF
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