担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

DOI： https://doi.org/10.4028/p-OMIw3U

記述言語：英語   掲載種別：研究論文（学術雑誌）

Fe-based nanocrystalline alloys have high magnetic flux density and low loss. Therefore, in this study, the magnetic domain structure of the ball-milled magnetic powders of these nanocrystalline alloys was observed using a Kerr effect microscope. The effect of strain removal heat treatment on the magnetic properties of the powder was also investigated by observing and comparing the magnetic domain structure of the milled powder before and after heat treatment during the preparation process of the nanocrystalline-milled powder. Our findings showed that the strain removal heat treatment changed the size and shape of the magnetic domains to a simple structure. In addition, the domain wall motion was found to be sensitive to the magnetic field, resulting in soft magnetic properties.

DOI： 10.1109/TMAG.2023.3283211

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

To realize the effective utilization of the end material and its application to a soft magnetic composite, Fe-based nanocrystalline alloy sheets were ball-milled, and platelet particles were obtained, in this work. Instrumental analyses revealed that although a micro strain was introduced into the nanocrystalline α-Fe grains in the achieved alloy powder, almost no changes were found in the amorphous part filled among the grains. The ball-milling treatment greatly increased the coercive force of the pulverized nanocrystalline sheet. Although the coercive force of the alloy powder decreased after the heat treatment, the coercive force remained to be approximately 10 times higher than that of the heat-treated alloy sheet without the ball-milling treatment, even after the heat treatment. The magnetic process of the ball-milled and heat treated nanocrystalline alloy powder will be discussed in detail in the conference based on the obtained results and Lorentz transmission electron microscopy.

DOI： 10.1109/INTERMAGShortPapers58606.2023.10228768

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

Fe–Si–B–P–Cu nanocrystalline alloy were treated with ball-mill using a lubricant as a process control agent (PCA). The resulting alloy powder is a strong candidate material for soft magnetic composites. Two ball milling methods (continuous and interval) were employed to control the interactions between the PCA and the alloy surface, and their effect on the microstructure of the prepared alloy particles was investigated. The alloy sheet was broken into small pieces and deformed plastically into flake-shaped particles regardless of the ball milling method implemented. Friction-force microscopy of the alloy immersed in the PCA revealed that the friction coefficient of the alloy surface exposed to air for a certain period was higher than that of the unexposed alloy surface (immediately after polishing). During ball milling, the ratio of the newly generated surface to the oxidized surfaces of the alloy subjected to interval milling was smaller than that of the alloy subjected to continuous milling. Therefore, the friction coefficient of the surface of the alloy subjected to interval milling was higher than that of the alloy subjected to continuous milling. Synchrotron radiation analysis revealed that the alloy subjected to interval milling exhibited enhanced surface friction, showing an obvious steepness and inflection in the diffraction intensity as a function of the tilt angle based on the Schulz reflection method. This indicates formation of crystallographic texture in α-Fe grains in an amorphous matrix. Hence, we demonstrated successfully that the ball milling process induced a crystallographic texture in the Fe-based nanocrystalline alloy due to plastic deformation due to the enhanced surface friction. The surface of the alloy was prepared based on the effect of the interfacial interactions between the alloy surface and the PCA.

DOI： 10.1016/j.heliyon.2022.e10325

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記述言語：中国語   掲載種別：研究論文（国際会議プロシーディングス）

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

記述言語：中国語   掲載種別：研究論文（国際会議プロシーディングス）

記述言語：中国語   掲載種別：研究論文（国際会議プロシーディングス）

記述言語：英語   掲載種別：研究論文（学術雑誌）

This article is the first work to carefully investigate the characteristics of iron loss per weight and relative permeability between the flake and spherical powders with a sinusoidal excitation up to a high frequency of 3.5 MHz in experiments using three separate measurement systems. The composition of the considered powder samples contains 0.001 wt% C, 0.012 wt% Si, 0.09 wt% Mn, 0.0004 wt% P, 0.008 wt% S, and 0.06 wt% O. The flake particle has the preferred orientation that the easy axes are normal to the platelet face, and the water atomized iron powder was processed with ball milling with the lubrication. Key objectives of the utilization of the three independent measurement systems with different specialized equipment and probes are to cross-check and overcome unexpected measurement errors of the related devices in use for validating measured results thoroughly. Experimental results demonstrate the much better performances on the iron loss per weight and relative permeability of the flake powder than that of the spherical powder at high frequencies. Physics-based explanations for the measured results are also presented. Furthermore, two estimation functions based on a six-parameter Steinmetz equation for the measured iron loss of the powders are developed by using MATLAB.

DOI： 10.1109/TMAG.2020.3014282

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

Soft magnetic composites (SMCs) are consolidated ferromagnetic powders covered with polymers. Ultra-thin flat powder can effectively reduce eddy current loss of SMCs, even at the frequency at which next-generation semiconductor devices are driven. In this study, pure iron powders were processed with ball-milling to obtain the ultra-thin powder and prepare the SMC. The effect of aspect ratio of the powder on the mechanical strength of SMC was investigated. Although the maximum bending stress of SMC made of iron particles with an aspect ratio of 1140 reached 60% of the strength of sintered iron powder, the increase in the maximum bending stress with increasing aspect ratio slowed down when the aspect ratio exceeded 100. The reason for the slowdown was assumed to be a decrease in insulating film coverage on the particle at high aspect ratio ranges due to the stacking and welding of particles during the ball milling process.

DOI： 10.1080/00325899.2021.2013622

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

Fe-based nanocrystalline alloy powder prepared by ball-milling is a potential candidate as a soft magnetic composite (SMC). Since the magnetic properties of particles having a random geometry arising from brittle fracture deteriorate by the presence of a demagnetising field, plastically deformed flake-shaped powders, exhibiting better magnetic properties on account of the suppression of any demagnetising field, are desirable. Microstructure such as grain size, lattice distortion and the distribution of dislocations, are affected by ball-milling treatment which changes the magnetic properties. In this study, Fe-based nanocrystalline alloy sheets are ball-milled with lubricant oil as a process control agent (PCA) and the microstructure of the particles investigated. The PCA effectively suppresses the brittle fracture of the alloy sheet during the ball-milling treatment and plastically deformed flake-shaped particles are then successfully obtained. Transmission electron microscopy reveals that there were few lattice defects in the α-Fe grain of the alloy, which indicated that almost only grain-boundary-mediated processes such as GB diffusion/sliding/migration and grain rotation dominate the deformation mechanism. However, Williamson–Hall analysis based on synchrotron radiation exhibits a slope indicating micro-strain in the α-Fe grains. It is found that the plastic deformation induced by the ball-milling treatment forms a microstructure having lattice distortion but containing few lattice defects. It is considered that a slight growth of the existing grains, which can be induced by thermal treatment, can achieve a strain- and dislocation-free microstructure, which is desirable for soft magnetic alloys.

DOI： 10.1080/09500839.2021.1953713

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記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2020 Elsevier Ltd The role of graphite/substrate interface in low-friction behavior of graphite was investigated. Iron and graphite powder mixtures were plastically deformed in either Ar–H2 or air atmospheres to obtain bare iron or iron oxide surface. Then, graphite particles adhered to and formed interfaces with surfaces. Friction force microscopy revealed that friction on particle surface milled in Ar–H2 atmosphere was obviously higher. X-ray absorption near-edge structure and transmission electron microscopy revealed that although the basal plane of graphite oriented along the oxidized surface, it did not occur along the bare iron surface, which explains the difference in lubricity on each surface.

DOI： 10.1016/j.triboint.2020.106455

Kyutacar

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記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2020 The Society of Powder Technology Japan In this study, Eu3+-containing amorphous silica nanoparticles and Eu compounds were successfully synthesized via a mechanochemical solid-state reaction between silica nanoparticles and EuCl3·6H2O. This reaction was induced by a grinding process, and the states of Eu3+ in the silica/europium composites were investigated. The silica/europium composites exhibited orange–red color luminescence owing to the 5D0–7F0, 5D0–7F1, and 5D0–7F2 transitions, which indicated the presence of Eu3+ in the silica framework and the newly formed Eu compounds such as EuOCl and Eu(OH)2Cl. The mechanochemical reaction because of the grinding process effectively induced an interaction between the silica surface and europium chloride; subsequently, Eu(OH)2Cl was formed in the silica/europium composites. Additionally, the Eu(OH)2Cl in the silica/europium composite exhibited a higher thermal stability than that of simple Eu(OH)2Cl, indicating that the mechanochemical reaction mediated the formation of Eu(OH)2Cl and new chemical bonding between the newly formed Eu(OH)2Cl and the silica surface, providing improved thermal stability to Eu(OH)2Cl. Thus, we successfully prepared silica nanoparticles containing not only Eu(III) in the silica framework but also Eu compounds that exhibit unique chemical bonding during a mechanochemical reaction.

DOI： 10.1016/j.apt.2020.07.013

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記述言語：英語   掲載種別：研究論文（学術雑誌）

This journal is © The Royal Society of Chemistry. We synthesized nanostructured mesoporous silica (MS)/hydroxyapatite (HA) hybrid particles in the presence of amphiphilic poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO20PPO70PEO20) triblock copolymer (P123). The particles exhibited slit-shaped mesostructures and underwent hybridization reaction between the MS and HA phases containing P123. Furthermore, the aggregated form of the particles exhibited dispersion stability in water in the monodispersed state (average particle size: 145 nm and coefficient of variation: 4.3% in the case of the maximum added amount of P123). Then, the structures of the hydration layer and the adsorbed protein on the particles were investigated to understand the effect of the hydration layer structures on the protein secondary structures. The ratio of the bonding water (intermediate and nonfreezing water) to free water increased upon hybridization, and it decreased with increasing P123 concentration. Upon hybridization, the component ratio of the asymmetric O-H stretching vibration between free water molecules decreased, and that of the symmetric O-H stretching vibration of intermediate water molecules increased. With increasing P123 concentration, the asymmetric O-H stretching vibration between free water molecules increased and the symmetric O-H stretching vibration of intermediate water molecules decreased. It was found that the protein native state component ratios of α-helix and β-sheet increased with increasing symmetric O-H stretching vibration between intermediate water molecules, and they decreased with decreasing asymmetric O-H stretching vibration between free water molecules. Moreover, the cytotoxicity against osteoblasts (MC3T3-E1) was evaluated and the hybrid particles exhibited a high cell density, indicating their bioactivity. On the hybrid particles interacting with P123, the cells were three-dimensionally assembled and uniaxially grown with the culture. Therefore, this is the first successful report of the synthesis of nanostructured MS/HA hybrid particles interacting with P123, and the controlled hydration layer structures on the particle surfaces were found to contribute to the protein secondary structures, promoting cytocompatibility.

DOI： 10.1039/c9tb02534k

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担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）

<p>Milling iron particles with a lubricant such as graphite deforms them into a platelet shape, and in the process, the (001) plane is oriented parallel to the platelet face. The (001) plane contains the <001> axis, which has excellent magnetic properties, making the particles ideal candidates for use as magnetic cores in motors. The effect of the graphite lubricant on the iron particles, i.e., the lubricity, depends on the milling atmosphere. X-ray absorption near edge structure (XANES) and transmission electron microscopy (TEM) observations reveal that this dependency is due to the difference in the orientation of the basal plane of graphite, where mechanochemically formed iron oxide at the graphite/iron interface most likely plays an important role in the orientation of the basal plane.</p>

DOI： 10.4164/sptj.57.196

CiNii Article

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2020 Elsevier B.V. In ball-milled iron particles for soft magnetic composites (SMCs), milling aids with lubricity can induce a (0 0 1) fiber texture with superior magnetic properties. Effects of lubricants on the recrystallization behavior of ball-milled iron particles with fiber texture and their magnetic properties of SMCs using the iron particles were investigated. During ball milling, lubricant oil and boron nitride (a solid lubrication particle) were used as lubricants. Both as-milled iron particles have a (0 0 1) fiber texture. However, when these iron particles are recrystallized using heat treatment, the iron particles milled using the lubricant oil almost disappeared while the fiber texture in the particles milled using the boron nitride was strongly retained. Therefore, it is concluded that ball milling for iron particles using boron nitride lubricant can retain (0 0 1) fiber texture in heat-treated iron particles, and SMC using these iron particles have higher permeability and lower coercive force.

DOI： 10.1016/j.jmmm.2020.167548

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記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2019 The Author(s) The aim of this study was to reveal the mechanism of enhancement of antibacterial properties of gray titania by plasma-sprayed hydroxyapatite (HAp)–amino acid fluorescent complexes under irradiation with visible light. Although visible-light–sensitive photocatalysts are applied safely to oral cavities, their efficacy is not high because of the low energy of irradiating light. This study proposed a composite coating containing HAp and gray titania. HAp itself functioned as bacteria catchers and gray titania released antibacterial radicals by visible-light irradiation. HAp-amino acid fluorescent complexes were formed on the surface of the composite coating in order to increase light intensity to gray titania by fluorescence, based on an idea bioinspired by deep-sea fluorescent coral reefs. A cytotoxicity assay on murine osteoblastlike cells revealed that biocompatibility of the HAp–amino acid fluorescent complexes was identical with the that of HAp. Antibacterial assays involving Escherichia coli showed that the three types of HAp–amino acid fluorescent complexes and irradiation with three types of light-emitting diodes (blue, green, and red) significantly decreased colony-forming units. Furthermore, kelvin probe force microscopy revealed that the HAp–amino acid fluorescent complexes preserved the surface potentials even after irradiation with visible light, whereas those of HAp were significantly decreased by the irradiation. Such a preservative effect of the HAp–amino acid fluorescent complexes maintained the bacterial-adhesion performance of HAp and consequently enhanced the antibacterial action of gray titania.

DOI： 10.1016/j.heliyon.2019.e02207

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記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2019 ISIJ. Soft magnetic powder compacts can suppress eddy current loss compared to conventional laminated cores. However, the compacts accompany greater hysteresis losses because the easy magnetization axes are not controlled in powders. In this study, a novel soft magnetic compact was prepared from a platelet-shaped iron powder with well-controlled easy magnetization axes and its effects on magnetic properties and crystal orientation of the compact were investigated. Such platelet iron powder was produced using a ball-milling process. During milling, the iron powder was subjected to the deformation, resulting in the shape change to the platelet. Simultaneously, a (001) fiber texture was formed preferentially, as it is characteristic of the deformed bcc metal. The powder was then compacted into a toroidal shape. The platelet surface of the powder was oriented so as to become parallel to the toroidal direction. Consequently, the easy magnetization axis, which lies along the platelet surface, was also oriented to the toroidal direction. The toroidal compact prepared in this way exhibited excellent magnetic properties. For example, the permeability was approximately 2.4 times higher than that of the compact prepared from a conventional iron powder.

DOI： 10.2355/isijinternational.ISIJINT-2018-521

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記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2018 Elsevier Ltd This study aims to reveal the effects of pressure during cold isostatic pressing (CIP) on the microstructure and optical properties of fluorescent HAp complexes. Although the microsturucture-dependent properties of fluorescent HAp complexes have been reported to improve the antibacterial properties of photocatalyst coating layers, the mechanism behind the changes in the fluorescence properties of highly compressed HAp complexes has not yet been unveiled. CIP was successfully used to fabricate fluorescent HAp – amino acid complexes, and their fluorescence intensities increased with increasing fabrication pressure. Peak wavelength of fluorescence emitted by the HAp – amino acid complexes exhibited yellow to red shift. Although the thickness of the amino acid layer was saturated in higher pressure cases, the concentration of amino acids increased proportionally with pressure, which suggests changes in the packing structures of the ligands in the HAp– amino acid complexes. Polarized Raman spectroscopy measurements clearly detected ligands normally arranged to the HAp layer under high pressure fabrication conditions, which can provide the tightly packed ligand structure in the HAp– amino acid complexes. These tightly packed ligand structure in the HAp– amino acid complexes could emit stronger fluorescence owing to the increased density of complexations. This newly found pressure dependency in the optical properties of HAp–amino acid complexes is beneficial for developing biocompatible fluorescence materials or enhancement agents for antibacterial coating layers.

DOI： 10.1016/j.jmbbm.2018.09.006

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記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2018 Elsevier B.V. The aim of this study is to observe visible light-induced antibacterial effects of the luminescent complex of hydroxyapatite and 8-hydroxyquinoline with gray titania coating. Plasma-sprayed Hydroxyapatite (HAp) coating has been widely used as bonding between alveolar bones with dental implants. However, bacterial infection on the surfaces of dental implants has recently been reported and conventional antibacterial technologies cannot last long-term use. Therefore a novel technology using the complex of hydroxyapatite and 8-hydroxyquinoline (8-Hq) with gray titania was proposed, which can be activated by visible light. Ti 2 O 3 powder was used in a plasma-spraying process to fabricate visible-light-sensitive titania coating. The plasma-sprayed HAp/Ti 2 O 3 was characterized by Raman Spectroscopy, FTIR and XRD. Its photo catalytic activity was evaluated using chemiluminescence observation and antibacterial property was evaluated by optical density measurement (OD), colony forming unit (CFUs) and fluorescent microscope observation. The plasma-sprayed Ti 2 O 3 powder revealed that its phase changed to TiO 2 (Rutile) though the color of the plasma-sprayed Ti 2 O 3 powder kept dark gray, which possessed its absorbency in visible-light region. The plasma-sprayed Ti 2 O 3 powder was then called gray titania and 1O 2 was generated from the gray titania by irradiating three types of laser (blue, green and red). Antibacterial evaluation revealed that both the existence of the complex and the irradiation of LEDs could significantly decrease the numbers of colony forming unit (CFUs). Furthermore, HAp-8Hq complex decreased adhesion of E. coli even without light irradiation. An enhancement in the antibacterial property of HAp complexes with gray titania coating can be attributed to an increased power density of light on the surface of gray titania by fluorescence.

DOI： 10.1016/j.apsusc.2018.04.106

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記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2018 The Japan Institute of Metals and Materials. The s-orbital energy level (Mk) of alloying elements in a Bi cluster was used to determine the composition for alloys of this system for use as Pb-free high-temperature solders. Binary Bi-Cu and Bi-Ag alloys with ΔMk of 0.013-0.343 and ternary Bi-2.0Ag-0.5Cu and Bi-5.0Ag-0.5Cu alloys with ΔMk of 0.180 and 0.379, respectively, were fabricated and tensile tested at 423 K; here, ΔMk is the compositional average of Mk. The flow stress and fracture strain at 423 K increased after the alloying elements were added to the alloys. The relationships between the 0.2% proof stress, ultimate tensile strength or fracture strain, and ΔMk were similar to those determined previously through tests performed at 293 K. Thus, these relationships could be useful for predicting the stress and fractures strain levels based on ΔMk, regardless of the temperature and alloy composition. Moreover, a transition from ductility to brittleness was observed at 348-373 K for both ternary alloys. In addition, the melting points of the ternary alloys lay between 536 and 538 K, indicating that the alloys would be suitable as hightemperature solders. The contact angles of molten droplets of 10 of the experimental binary and ternary alloys on a Cu plate as determined at 973 K were 24-30°. This confirmed that the alloys exhibited good wettability with respect to Cu. Finally, the ternary Bi-2.0Ag-0.5Cu and Bi-5.0Ag-0.5Cu alloys showed thermal conductivities of 12.1 and 15.9 W/m/K, respectively, at 373 K; these were lower than that (30.4 W/m/K) of Pb-5Sn.

DOI： 10.2320/matertrans.MAW201710

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記述言語：日本語   掲載種別：研究論文（学術雑誌）

DOI： 10.32163/amadareport.31.0_79

CiNii Article

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記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2017 Elsevier B.V. The process of texture formation on iron particles was investigated via simple ball milling using graphite particles as milling aid. During milling, the shape of the iron particles changed from granular to platelets owing to repetitive compression and balls rolling in a direction perpendicular to the platelet faces. Simultaneously, a {001} + {111} double-fiber texture was formed, which is characteristic of a metal with a bcc structure deformed under uniaxial compression and multidirectional rolling. Based on these observations, it is concluded that the texture obtained through simple ball milling was induced by uniaxial compression and a multidirectional-rolling-like deformation. Since the main component of the double-fiber texture is {001} and the easy magnetization axes 〈001〉 are oriented toward the in-plane directions with the platelet face in the texture, the iron particles are ideal candidates for use as magnetic cores in motors, inductors, and other electromagnetic parts.

DOI： 10.1016/j.powtec.2017.08.010

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記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2017, © The Author(s) 2017. A simple rubbing treatment was used to mechanochemically modify the surface of polyacrylonitrile-based carbon fibers and its effect on their surface structure and functional groups was studied using several surface characterization techniques. To control the mechanochemical effect, the shear forces accompanying rubbing were kept constant. Scanning electron microscopy tests and the peak positions and widths of the main Raman spectroscopy bands indicated that there were no morphological changes to the carbon fibers following rubbing. In contrast, X-ray photoelectron spectroscopy showed an increase in oxygen-containing functional groups; in addition to hydroxyl species, the main groups introduced were alkoxide, carbonyl, and carboxyl groups. The ratio of carboxyl groups on the carbon fiber surface increased with the shear force magnitude, indicating carbon surface oxidation. The difference between the Raman and X-ray photoelectron spectroscopy results indicates that the modification was confined to the first few atomic layers; therefore, this rubbing method is capable of producing efficient mechanochemical surface modification of carbon fibers. This technique is simple, is relatively inexpensive, and is applicable to carbon fiber-reinforced plastic processing techniques.

DOI： 10.1177/0021998316687030

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記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2017 Elsevier B.V. Organic/inorganic hybrids of 8-hydroxyquinoline (8Hq) molecule and hydroxyapatite nanocrystal (HAp) were mechanochemically prepared. In the hybrids, a green photoluminescence peak at 500 nm newly appeared, suggesting the chemical bonding of the 8Hq molecule with the Ca2+ ions of HAp. Then, the organic/inorganic interfacial photofunction was clarified by a molecular orbital calculation. The interfacial chemical bonding between the O and N atoms of 8Hq and the Ca2+ ions of HAp was attributed to both covalent O[sbnd]Ca and ionic N[sbnd]Ca. The resultant wave functions revealed that the green luminescence was attributed to metal-to-ligand charge transfer (MLCT) from the O atoms of phosphate group (HAp) to the π-cloud (8Hq) in the HOMO of the hybrids. Therefore, the photofunctional interfaces of the hybrids were successfully demonstrated.

DOI： 10.1016/j.optmat.2017.02.036

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記述言語：英語   掲載種別：研究論文（学術雑誌）

©2017 The Japan Institute of Metals and Materials. The s-orbital energy levels (Mk) of some alloying elements in a Bi cluster model were obtained on the basis of the molecular orbital calculation. In contrast, binary Bi-Cu/-Ag/-Zn system alloys with ΔMk of 0.013-0.343 were manufactured and tension- or hardness-tested, where ΔMk was the compositional average of Mk. The ultimate tensile strength and hardness were improved as alloying elements were added and increased in alloys. There was the relation between the ultimate tensile strength, fracture strain or hardness and ΔMk. Further, the compositions of Bi-2.0Ag-0.5Cu (ΔMk: 0.180), Bi-5.0Ag-0.5Cu (ΔMk: 0.379) and Bi-0.25Cu-0.25Sb (ΔMk: 0.044) were proposed as ternary alloys. It is found that the ultimate tensile strength, fracture strain and hardness values of ternary alloys could be also able to predict using their estimation lines obtained from binary Bi system alloys.

DOI： 10.2320/matertrans.MA201605

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記述言語：英語   掲載種別：研究論文（学術雑誌）

© The Royal Society of Chemistry. To develop a novel cancer cell imaging approach, we fabricated surface-engineered mesoporous silica (MPS) particles with multi-functionalities. Specifically, mechanochemically-treated europium(iii)-doped MPS (Eu:MPS) particles were prepared, and a folate N-hydroxysuccinimidyl ester (FA-NHS) molecule was immobilized on the particle surface as a targeting ligand for specific types of cells. With the mechanochemical treatment, the siloxane bonds were changed to show better luminescence quantum efficiency as revealed by 29Si-NMR and photoluminescence spectroscopy, suggesting interaction changes between the silica framework structures and the doped Eu ions. Furthermore, the mechanochemically-treated particles immobilized with FA-NHS specifically bind to the cancer cells and the subsequent uptake by the cells was in situ observed using time-lapse optical microscopy. The particles did not exhibit any toxicity in the cellular proliferation stages. The particles after the binding and uptake also showed intense luminescence from the cells at a culture time of 24 h, demonstrating a clear imaging ability along with all the cellular shapes. Therefore, the present surface-engineered luminescent particles will be used for specific cancer targeting and imaging purposes.

DOI： 10.1039/c7ra00535k

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記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2016 American Chemical Society. To clarify hydroxyapatite (HAp) nanocrystal formation based on the interfacial interactions with organic molecules is important for controlling the dispersion states/shapes of HAp and understanding the biomineralization mechanism. In this study, the effects of cetyltrimethylammonium bromide (CTAB) micelles on the HAp nanocrystal formation process were investigated through both the morphosynthesis technique and the molecular orbital calculations. The HAp nanocrystals synthesized in the presence of CTAB exhibited a controlled rod-like shape and subsequently grew up by a thermal treatment to be larger-sized nanocrystals at a well-dispersed state. It was also found that the CTAB micelles strained and disordered at the higher temperature effectively induced heterogeneous nucleation to initiate the nucleation/growth processes. In contrast, HAp nanocrystals synthesized without CTAB exhibited irregular-shaped and aggregated nanocrystals, which are due to dominantly occurring homogeneous nucleation. According to the molecular orbital calculations, the cationic N atom of the CTAB molecule strongly interacted with the Ca ion in the a-plane as well as the hydroxyl/phosphate groups in the c-plane of HAp via ionic/covalent bonding (e.g., only ionic bonding at the closer interfacial distance at 1.0 Å), leading to effective nucleation on the micelle surfaces. Therefore, a possible reason for the rod-like and well-dispersed nanocrystal formation is due to the heterogeneous nuclei formation/growth on the N atoms of CTAB micelles and subsequent fusion growth among the CTAB micelle-directed inorganic-organic complexes in the confined spaces. The present results will be applicable for designing tailored HAp morphologies based on inorganic-organic hybrid interaction systems.

DOI： 10.1021/acs.cgd.5b01599

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記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2016 The Japan Institute of Metals and Materials. The effectiveness of the electronic parameter on the predicting the mechanical properties of Zn system alloys for high temperature applications was evaluated in order to satisfy both the tensile strength of 200 MPa and elongation of 5%. The electronic parameter was used s-orbital energy level (ΔMk) in this study. Promising composition of alloys were Zn-4Al-7Sn, Zn-10Al-0.5Sn, Zn-10Al-2Sn and Zn-5.1Al-0.5Sn in mass%, and their ΔMk values were 0.079, 0.080, 0.089 and 0.045, respectively. The experimental results of tensile test for designed alloys showed that the tensile strength of 195-225 MPa depend on the increment of ΔMk values, and elongation are 4.5-5.1%. Optimization of composition on Zn system alloys was found to be speedy and precisely achieved using the ΔMk parameter. The wetting contact angles between Cu plate and the designed alloys of Zn-4Al-7Sn, Zn-10Al-0.5Sn, Zn-10Al-2Sn and Zn-5.1Al-0.5Sn at 973 K in the Ar stream are 33.8°, 43.3°, 50.1° and 44.3°, respectively, suggesting that the designed alloys can be practically applied at high temperature. Moreover, the thermal conductivity, tensile test of designed alloys at high temperature were also evaluated.

DOI： 10.2320/matertrans.MBW201514

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記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2015 Elsevier B.V. All rights reserved. Cold isostatic pressing successfully formed a chelate complex of 8-hydroxyquinoline (8Hq) molecules on plasma-sprayed hydroxyapatite (HAp) coating by solid-state reaction. The complex emits a fluorescence peak at approximately 500 nm by UV irradiation. The red shift of the fluorescence was newly observed in the cases of highly compressed complex due to π - π stacking of aromatic ring in the molecular structure of 8Hq. The immersed complex coating in Simulated Body Fluid (SBF) demonstrated amorphous apatite precipitation and kept its fluorescence property.

DOI： 10.1016/j.msec.2015.08.020

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記述言語：日本語   掲載種別：研究論文（学術雑誌）

This study aims at forming a fluorescent complex between HAp coatings with ligands of amino acid by using CIP process in order to suppress cytotoxicity of conventional fluorescent HAp complex and also enhance antibacterial properties by visible light irradiation. Three amino acids, phenylalanine, tryptophan and tyrosine were used in the CIP process. By applying pressures from 200 MPa to 800 MPa, fluorescence of HAp with the three amino acids was successfully observed by UV irradiations. In the case of highly compressed samples, fluorescence in some regions was shifted to longer wavelength. Cytotoxicity assessments were conducted by using MC3T3-E1 osteoblast cells. Observing optical density of mediums after cultivations revealed that there were no significant differences among five groups in cases of same culture periods. The results demonstrated that biocompatibility of HAp/amino acid complex was similar to HAp itself.

DOI： 10.1299/jsmebio.2016.28._2G44-1_

CiNii Article

その他リンク： https://ci.nii.ac.jp/naid/110010052253

記述言語：英語   掲載種別：研究論文（学術雑誌）

CiNii Research

記述言語：日本語   掲載種別：研究論文（学術雑誌）

This study aims at forming a fluorescent complex between HAp coatings and amino acid ligands by using CIP process in order to suppress cytotoxicity of conventional fluorescent HAp complex and also enhance antibacterial properties by visible light irradiation. Three amino acids, phenylalanine, tryptophan and tyrosine were successfully fabricated by applying pressures 800 MPa for 1.2 ks. Fluorescence by complex of HAp with three amino acids was observed by UV irradiations. Cytotoxicity assessments were conducted by using MC3T3-E1 osteoblast cells. Observing optical density of mediums after cultivations revealed no significant differences among five groups in the same culture periods. The results demonstrated that biocompatibility of HAp/amino acid complex was similar to HAp itself. The reduction of bacterial growth rate was observed in antibacterial evaluation after irradiating visible light. The fluorescent complex HAp/ photocatalyst coating showed significant reducing of bacterial growth rate comparing with the cases by non-fluorescent HAp coating.

DOI： 10.1299/jsmehs.2016.53._917-1_

CiNii Article

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記述言語：日本語   掲載種別：研究論文（学術雑誌）

DOI： 10.11279/jfeskouen.168_98

CiNii Article

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記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2015 Author(s). Crystallographically anisotropic platelet iron particles were successfully prepared using a conventional ball mill with addition of graphite (Gp) particles. The morphological and structural changes resulting from the milling were investigated using scanning electron microscopy and X-ray diffraction. The spherical iron particles were plastically deformed into platelet shapes during the milling. Simultaneously, it is suggested that the size of the Gp particles decreased and adhered as nanoparticles on the surface of the iron particles. The adhered Gp particles affected the plastic deformation behavior of the iron particles: the {001} planes of α-iron were oriented parallel to the particle face, and no preferred in-plane orientation was observed. This study not only details the preparation of soft magnetic metal particles that crystallographically oriented to enhance their magnetic properties but also provides new insight into the activities of the well-established and extensively studied mechanical milling method.

DOI： 10.1063/1.4930915

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記述言語：英語   掲載種別：研究論文（学術雑誌）

Composites between carbon fibers (CFs) and heterogeneous materials have been widely studied and their fabrication techniques have been developed. However, their hydrophobic surfaces make it difficult to disperse CFs into hydrophilic resins, which results in weak junctions with ceramics. To develop high-strength composite fibers, it is important to design interfacial chemical bonds. Thus, surface-modification techniques of CFs have recently become the main focus and their interfaces have been characterized by various analytical methods. In this Minireview, various techniques that modify the CF surface by coating with inorganic polymers (metal oxide compounds) are highlighted, and the applications of novel nanocomposite fibers are also described. Furthermore, interfacial bonds between CFs and polymer resins are reviewed and discussed in terms of CF-reinforced plastics and their future prospects. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

DOI： 10.1002/cplu.201300356

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記述言語：英語   掲載種別：研究論文（学術雑誌）

The mechanochemical milling was utilized to control the nanostructures of plate-like graphite (Gp) microparticles in an argon atmosphere and at room temperature. The aggregated Gp nanoparticles were prepared by the simple solid-state process without organic solvent. Electron microscope observations, X-ray diffraction patterns and Raman spectra revealed the fractured plate-like Gp microparticles as well as the Gp microparticles agglomerated to each other through the dissociative edge surfaces by the milling process to finally generate the Gp nanoparticle aggregates. In the process, the ratio of the edge plane surfaces with the dangling bondings to layered internal surfaces clearly increased with the milling. Therefore, the low environmental burden process for preparing the Gp nanoparticle aggregation was achieved. © 2014 Elsevier Ltd.

DOI： 10.1016/j.ssc.2014.03.023

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記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2014 American Chemical Society. Mechanochemically activated graphite (Gp) and iron particle surfaces were prepared, and the Gp/iron composite interfaces were elucidated to utilize new functions. Activated iron particles with the oxygen atoms prepared by a milling under oxygen atmosphere were shown. Alternately, the Gp particles activated by the milling under argon atmosphere easily agglomerated because of the dangling bonds on the edge surfaces. In the composites, the interfacial bonds (e.g., Fe-O-C) between the Gp and iron oxides on the iron were clearly induced while preserving the carbon atom six-ring structures. Furthermore, the molecular orbital calculations suggested that the activated oxygen atoms in the iron oxides effectively abstract hydrogen atoms from the C-H groups of the Gp edge, resulting in the active bare carbon atoms which can form the interfacial bonds; therefore, the interfacial Fe-O-C bonds for a higher adhesive strength were successfully prepared.

DOI： 10.1021/ie501207u

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記述言語：英語   掲載種別：研究論文（学術雑誌）

Mechanochemically activated iron oxide formation on α-iron (Fe) microparticles for the efficient reaction with methane (CH4) was investigated using a simple milling process to successfully clarify the efficient CH4 adsorption as well as the C-H bonding dissociation. First, the oxides with different oxidation degrees (i.e., disordered or ordered iron oxides) were formed on the Fe by mechanochemical milling under an oxygen atmosphere. The surface analyses by X-ray diffraction, Raman, and X-ray photoelectron spectroscopy (XPS) revealed that the surface iron oxides consisted of two phases (α-Fe2O3 and Fe3O 4), and the Fe2O3-like structure was dominantly grown on the near-surface of the disordered iron oxides during the initial oxidation time (0.08 and 0.80 h). Furthermore, the signals from an electron spin resonance analysis suggested dangling bondings on the disordered oxides, indicating the successful formation of the active O sites. Second, the mechanochemical reaction of the resultant iron oxide surfaces with CH 4 was investigated. As a result, the efficient CH4 adsorption as well H2 generation were prominently observed on the disordered oxides, indicating an effectively dissociative adsorption. XPS analysis of the resultant particles revealed that the C-H bonding dissociation dominantly occurred on the near-surface oxygen atoms. Furthermore, using a molecular orbital calculation analysis, the activated O atoms with dangling bondings in the disordered iron oxides were found to affect the C-H dissociation of the adsorbate molecules (e.g., CH4 and CH3•) and exhibit an efficient H2 generation. On the other hand, the O atoms in the ordered lattice could not induce the C-H dissociation of CH3• to produce the equilibrium adsorption/desorption states and lower H2 generation amount, suggesting the importance of both the force-induced activated O atoms and closest interatomic distances. Therefore, we first achieved the efficient mechanochemical decomposition of CH4 and CH3• to generate H2 by the disordered iron oxide surfaces on α-Fe particles. © 2013 American Chemical Society.

DOI： 10.1021/jp405316t

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記述言語：英語   掲載種別：研究論文（学術雑誌）

composites between carbon fibers (CFs) and heterogeneous materials have been widely researched, and fabrication techniques have been developed. However, because the CF surfaces are hydrophobic, they poorly disperse into hydrophilic resins and do not form junctions with ceramics. For designing and developing high-strength composites, it is important to investigate and design the interfacial chemical bonds. Thus, recently, research focusses on surface modification and coating techniques of CFs. In this review paper, various surface modification and coating by inorganic polymers (metal oxide compounds) were highlighted to focus the functionalization of the CF surfaces. The applications for novel composite materials was also investigated. Furthermore, the interfacial bonding techniques between CF and polymer resin for carbon fiber reinforced plastic and their future perspectives are reviewed and discussed. ©2013, The Society of Polymer Science, Japan.

DOI： 10.1295/koron.70.242

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記述言語：英語   掲載種別：研究論文（学術雑誌）

The mechanochemical surface functionalization of iron oxides with disordered lattices on bare iron (Fe) particles was investigated using simple milling processes to clarify the formation mechanism of the oxide layer and investigate the near-surface models with different states. The homogeneous α-Fe particles at the milling equilibrium were first prepared under an argon atmosphere. After the subsequent milling reaction of the particles with oxygen molecules, the surface analyses by X-ray diffraction and Raman and X-ray photoelectron spectroscopies revealed that the near-surface layers consisted of two iron oxide phases (α-Fe2O3 and Fe 3O4) through oxygen atom diffusion, and the α-Fe2O3 was dominantly grown on the near surface. During the initial reaction, the signals from an electron spin resonance suggested the dangling bond formation on α-Fe2O3. The oxygen atoms effectively induce disordered lattices in the local area to form oxidized Fe3+ clusters, and the geometric distortion formed the dangling bonds, which were theoretically supported by a molecular orbital calculation to elucidate the increase in the unpaired electron sites on the α-Fe2O3. Therefore, the defective Fe3+ ions induced by the lattice mismatching between the clusters and bare α-Fe are found to form the disordered lattice that contains the oxygen atoms with unpaired electrons, which are successfully induced by the near-surface strain based on the simple mechanochemical reactions. The patterns of surface activation of the Fe particle surfaces by oxidization will be capable of novel chemical reactions by selective oxygen insertion as well as deep oxidation. © 2013 American Chemical Society.

DOI： 10.1021/jp401655m

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記述言語：英語   掲載種別：研究論文（学術雑誌）

The fabrication of iron-graphite composites was investigated using a milling process. Based on the milling time of the process, the average particle size of the host iron particles decreased to 10 μm. The size of the graphite particles decreased to a nanometer scale, resulting in the graphite strongly adhering to the iron surfaces. Raman spectra revealed that the graphite aromatic ring structure disappeared and the iron near-surface layer was changed to iron oxide phases. The dangling bond of the fragmented graphite combined with the oxidized iron surface by interfacial binding to efficiently form the interfacial composites. © The Author(s) 2012 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

DOI： 10.1177/0021998312446502

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記述言語：英語   掲載種別：研究論文（学術雑誌）

The mechanochemical fabrication of the composites between carbon fibers (CFs) and nylon-6 (N6) was investigated using a milling process. By the milling, defected surfaces were generated on CFs to obtain the homogeneous length with preserving the cylindrical shape of CF. Fourier transform infrared spectra revealed that the band intensities due to C-O, C-N and O-H bondings increased with the milling. The band position of C-N was shifted to a higher wavenumber, while that of C-O did not change, implying that the main chain of N6 was dissociated at the C-N neighboring the C-O bonds by the force, and subsequently, new bonds between the N atoms of the activated N6 and the C atoms on CFs would be formed. Therefore, the efficient fabrication of the CF/N6 composite fibers with the interfacial bondings was achieved using the mechanochemical reaction. © 2013 American Chemical Society.

DOI： 10.1021/ie301333n

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記述言語：英語   掲載種別：研究論文（学術雑誌）

Experimental and theoretical studies of the interfacial reactions between methane and mechanochemically activated iron particles were investigated using a milling technique and a discrete variational molecular orbital calculation. The particles were milled in a stainless steel vessel under a methane atmosphere. Scanning electron microscope (SEM) images revealed that the particles welded together to form larger particles and subsequently fractured into smaller homogeneous particles. The inner pressure of the vessel decreased with increasing milling time, indicative of methane adsorption on the particle surfaces and hydrogen was detected by gas chromatog-raphy. Two possible reactions promoted by milling are postulates: (i) fixation of adsorptive methane on the iron particles, and (iij methane conversion to hydrogen on the naturally oxidized iron. A bond overlap population (BOP) calculation was performed to evaluate the molecular orbital interactions between the methane and iron-particle surfaces. The covalent BOP exhibited a maximum positive value at a distance of 0.15 nm between the hydrogen atom of tetrahedral vertex and the iron atom facing each other at their interface, indicating methane adsorption on the iron particle surfaces. The BOP values between the hydrogen atoms of tetrahedral plane (not facing the iron) and carbon atom of methane decreased slightly with decreasing distance, indicating a dissociative adsorption state and weakened strength of the covalent C-H bond. These phenomena would be affected primarily by the strain in the iron particles and the forces between the methane and the near-surface iron and oxygen atoms. Therefore, methane adsorption and dissociation at the interface are consistent with the mechanochemical conversion of methane to hydrogen on the mechanochemically activated iron-particle surfaces.

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記述言語：英語   掲載種別：研究論文（学術雑誌）

The fabrication of copper-graphite composites by a milling process was investigated using a centrifugal ball mill. The copper particles were homogeneously milled in a graphite vessel, and the reaction time was varied. Scanning electron microscopy images clearly revealed that a fragment of graphite ground by the copper particle adheres to the copper particle surface, indicating the formation of a copper-graphite composite. The composite graphite amount per 1 g of copper particles increased to 0.46 mg at the milling time 5 min, and subsequently decreased to 0.25 mg at 60 min, indicating the suitable milling-time for the interfacial adhesion. When using only the copper particles, the naturally oxidized layer on the surface decreased with milling. On the other hand, when using only the graphite, the characteristic graphite structure is disrupted and the defect structure increased with milling. Thus, the new copper surface generated by milling strongly reacts with the defect structure of the graphite. It is suggested that the interfacial bonding between the copper and graphite was attributed to a Van der Waals attraction and/or binding force due to oxygen atoms located at the interface. © The Author(s) 2012 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

DOI： 10.1177/0021998311432947

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記述言語：英語   掲載種別：研究論文（学術雑誌）

The incorporation of anthracene (Ant) into nanoporous silica/surfactant nanocomposite spheres was successfully achieved using a mechanochemical solid state reaction. The Ant molecules were incorporated into the nanopores while preserving the silica nanostructures, indicating the effective hydrophobic interactions with the alkyl chains of the surfactant. The blue photoluminescence intensity due to the monomer state was enhanced by increasing the mechanochemical milling force, suggesting this is an efficient preparation method for a luminescent medium by monomeric assembly of the Ant molecules. © The Royal Society of Chemistry.

DOI： 10.1039/c2jm34155g

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記述言語：英語   掲載種別：研究論文（学術雑誌）

Hybrid nanocrystals of 8-hydroxyquinoline (8Hq) molecules and hydroxyapatite nanocrystals (HAp) were successfully prepared by a mechanochemical solid-state reaction. The hybrid nanocrystals exhibit a significant thermal stability and efficient photoluminescence peak at 500 nm, which were attributed to metal-ligand charge transfer at the interface between the oxygen atoms of 8Hq and the calcium ions of HAp, and the interfacial photofunctions were mechanochemically controlled. The interfacial bonding structures were also supported by a DV-Xα molecular orbital calculation. © 2012 American Chemical Society.

DOI： 10.1021/ie301755z

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

Collagen fibril membranes (CFMs) with a high mechanical property were fabricated with a lateral face evaporation method, in which type I atelocollagen extracted from tilapia scales was used. The density and thickness of the CFM obtained were 0.51 ± 0.04 mg/cm 3 and 50 ± 5 μm. The collagen fibrils in the CFM had a similar periodic stripped pattern of 67 nm with native collagen fibrils. The CFM was crosslinked in gaseous glutaraldehyde for different duration in order to increase the mechanical property. The crosslinking degrees of the CFMs analyzed by free amino groups gradually increased to 70.3 % against the exposure duration until 6 hours, and reached a plateau. The denaturation temperatures of the CFMs with the crosslinking degrees at 20.4 % to 43% were linearly increased from 49°C to 75°C. The tensile strength of the CFMs was slightly improved until the crosslinking degree at 33.3 % and then the tensile strength rapidly increased to be 68 MPa. It was suggested that a percolation phenomenon took place in the CFMs by crosslinking of collagen fibrils with polymerized GA molecules. © 2012 Materials Research Society.

DOI： 10.1557/opl.2012.396

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記述言語：英語   掲載種別：研究論文（学術雑誌）

Europium (III) (Eu 3+)-doped nanoporous silica spheres were synthesized, and the states of Eu 3+ ions in the silica framework structure were investigated. The ordered nanopores were preserved with the doping at the Eu 3+ molar concentration to Si up to 10mol%, and the O-Si-O and Si-OH groups in the structures were clearly rearranged with the doping, indicating the interaction of Eu 3+ with the O atoms. The significant morphological changes in the spheres were observed with the doping. The photoluminescence spectral shapes due to the transitions of 5D 0- 7F 1 and 5D 0- 7F 2 were indicative of the presence of the Eu 3+ in an environment of a low symmetry. It was found that the Eu 3+ was located inside the silica framework to electrostatically interact with the environmental O atoms, which would prevent the aggregation among Eu 3+ ions to show the efficient luminescence. Therefore, the interactions between the Eu 3+ ions and silica framework structures in the spheres were successfully clarified. © 2011 Elsevier Inc.

DOI： 10.1016/j.jcis.2011.07.066

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記述言語：英語   掲載種別：研究論文（学術雑誌）

Europium (III) (Eu3+)-containing nanoporous silicas were successfully synthesized by two different loading methods (adsorption or doping), and the states of the Eu3+ in the structure were investigated. The Eu3+-adsorption indicated that the Eu3+ interacts with hydroxyl groups on the pore surface and H2O molecules to enhance the quenching, whereas the Eu3+-doping indicated that the Eu3+ was located inside the structure framework that produced the efficient luminescence. The interaction between the Eu3+ and silica structure depended on the loading method. © 2011 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.matlet.2011.04.011

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

A fundamental study on the reaction between CO2 and mechanically activated metal powders has been conducted. In this research, the behavior and mechanism of CO2 reaction under various grinding conditions were investigated to fix and reduce CO2. The powder used was placed inside a grinding vessel, and was ground together with the SUJ2 balls in CO 2 atmosphere. It was found that only the adsorption of CO2 gas on the ground samples was observed, whereas the decomposition of CO 2 was not occurred. The CO2 adsorption increased proportionally with the increase in the grinding speed, weight of sample and number of SUJ2 balls. Furthermore, the CO2 adsorption increased with the decrease in the standard free energy of formation of each metal oxide. The morphology of the sample observed by SEM showed that the samples were not crushed into finer particles, but were only grazed on the sample's surface. Therefore, it can be said that the CO2 can be adsorbed on the mechanically activated samples by using the centrifugal type ball mill, but in order to enhance the amount of CO2 adsorption, another type of machine with higher grinding intensity should be considered. © (2010) Trans Tech Publications.

DOI： 10.4028/www.scientific.net/AMR.129-131.799

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受賞国：日本国