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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.

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.

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.

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. Ti2O3 powder was used in a plasma-spraying process to fabricate visible-light-sensitive titania coating. The plasma-sprayed HAp/Ti2O3 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 Ti2O3 powder revealed that its phase changed to TiO2(Rutile) though the color of the plasma-sprayed Ti2O3 powder kept dark gray, which possessed its absorbency in visible-light region. The plasma-sprayed Ti2O3 powder was then called gray titania and 1 O 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.

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.

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 Ca 2+ 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 Ca 2+ ions of HAp was attributed to both covalent O Ca and ionic N 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.

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.

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.

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 t...

Cold isostatic pressing successfully formed a chelate complex of 8-hydroxyquinoline (8 Hq) 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 8 Hq. The immersed complex coating in Simulated Body Fluid (SBF) demonstrated amorphous apatite precipitation and kept its fluorescence property.