The Oxidation of Equol by Tyrosinase Produces a Unique Di-ortho-Quinone: Possible Implications for Melanocyte Toxicity

Equol (7-hydroxy-3-(4′-hydroxyphenyl)-chroman, EQ), one of the major intestinally derived metabolites of daidzein, the principal isoflavane found in soybeans and most soy foods, has recently attracted increased interest as a health-beneficial compound for estrogen-dependent diseases. However, based on its structure with two p-substituted phenols, this study aimed to examine whether EQ is a substrate for tyrosinase and whether it produces o-quinone metabolites that are highly cytotoxic to melanocyte. First, the tyrosinase-catalyzed oxidation of EQ was performed, which yielded three EQ-quinones. They were identified after being reduced to their corresponding catechols with NaBH₄ or L-ascorbic acid. The binding of the EQ-quinones to N-acetyl-L-cysteine (NAC), glutathione (GSH), and bovine serum albumin via their cysteine residues was then examined. NAC and GSH afforded two mono-adducts and one di-adduct, which were identified by NMR and MS analysis. It was also found that EQ was oxidized to EQ-di-quinone in cells expressing human tyrosinase. Finally, it was confirmed that the EQ-oligomer, the EQ oxidation product, exerted potent pro-oxidant activity by oxidizing GSH to the oxidized GSSG and concomitantly producing H₂O₂. These results suggest that EQ-quinones could be cytotoxic to melanocytes due to their binding to cellular proteins.     

High-speed and high-backdrivable actuation system considering variable-structured elastic design

This paper proposes a high-speed high-backdrivable actuator using a new actuation structure. To realize a small-sized high-torque actuator, a reduction gear is usually used. Because of the current saturation and friction effect of the actuator, the actuator has maximum values of acceleration and rotation speed. A gear with a high gear ratio reduces these two maximum values because of the presence of a reduction mechanism. The trade-off between the output torque and rotation speed exists. Consequently, it is difficult to achieve high-speed motions using a gear. Moreover, the reduction mechanism increases the friction of the motor and deteriorates its backdrivability. Therefore, in this study, a new actuation mechanism is utilized to solve such problems. The new mechanism consists of an electromagnetic clutch and elastic spring. High backdrivability and high-speed motion are achieved by releasing the clutch and transforming the elastic potential energy accumulated by the geared motor into kinetic energy, respectively. In the proposed system, the output rotation speed exceeds the maximum rotation speed obtained after it is reduced by the gear. Finally, the validity of the proposed method is verified experimentally.     

High throughput and exhaustive analysis of diverse lipids by using supercritical fluid chromatography-mass spectrometry for metabolomics

We have developed an analytical system that enables the simultaneous rapid analysis of lipids with varied structures and polarities through the use of supercritical fluid chromatography-mass spectrometry (SFC-MS). The separation conditions for SFC (column, modifier, back pressure, etc.) and the detection conditions for mass spectrometry (ionization method, parameters, etc.) were investigated to develop a simultaneous analytical method for lipid mixtures that included phospholipids, glycolipids, neutral lipids, and sphingolipids. When cyanopropylated silica gel-packed column was used for the separation, all lipids were successfully detected and the analysis time was less than 15 min. The use of an octadecylsilylated column resulted in separation, which was dependent on the differences in the unsaturation of the fatty acid side chains and isomer separation. This system is a powerful tool for studies on lipid metabolomics because it is useful not only as a fingerprinting method for the screening of diverse lipids but also for the detailed profiling of individual components.     

Molecular dynamics studies of thin film growth by ionized cluster beam deposition

The mechanism of thin-film growth by ionized cluster beam deposition (ICBD) has been investigated, using molecular dynamics (MD) simulations with the hybrid interatomic potentials which have been developed by combining the embedded-atom-method (EAM) potentials with the screened Coulomb average modified Lenz–Jensen (AMLJ) potential. In order to clarify the conversion mechanism of cluster energy into surface migration energy in ICBD, we have investigated the cluster impact phenomena for Cu₂₀₁ impact on Cu (1 1 1) and Pt (1 1 1) with a cluster energy of 5 eV/atom. For a Cu₂₀₁ impact on a Pt (1 1 1), a half of cluster atoms migrated on the substrate surface with relatively high migration energies. On the other hand, for a Cu₂₀₁ impact on a Cu (1 1 1), most of the cluster atoms are embedded into the substrate, and a small amount of them migrate with small migration energies. In the conversion mechanism of cluster energy into surface migration energy in ICBD, the most important point is whether the high-density zone is formed in the central part of the cluster, above or below the surface.     

Solution‐processed organic TFT array for active‐matrix LCDs on a plastic substrate

Abstract— Organic TFTs (OTFTs) have been developed with a novel solution‐processed gate insulator of poly(4‐vinylphenol) (PVP) with the addition of octadecyltrichloro‐silane (OTS) and a solution‐processed organo‐silver electrode/wire to improve the performance of an OTFT and to maked high‐throughput‐manufacturing process possible. Solution‐processed PVP has also employed for a buffer layer on a plastic substrate. The OTFT backplane with these solution‐based organic‐material technologies has been successfully applied to drive a 2.5‐in. QQVGA (160 × 120 pixels) AMLCD with a resolution of 79 dpi.     

Mineral matter effects on air-oxidation of cokes from a coking coal

Indigenous mineral matter in coal affects the chemical reactivity of resulting cokes through both catalytic graphitization and catalytic gasification. The significance of both catalytic effects on air-oxidation was examined using cokes from a medium-volatile bituminous coking coal with 9 wt% mineral matter. Catalytic graphitization by mineral matter enhanced the reactivity of the resulting coke in spite of the formation of highly crystalline carbons. This effect, however, was less than that of catalytic gasification by mineral matter. The coke from the acid-treated predemineralized coal exhibited no catalytic effects but was the most reactive. The implications of these results are discussed in detail.     

A flexible OLED display with an OTFT backplane made by scalable manufacturing process

Abstract— A full‐color top‐emission AMOLED display driven by an organic TFT backplane manufactured using a scalable, lift‐off‐free, and shadow‐mask‐free process has been developed. It was shown that cost‐efficient copper can be used for S/D electrodes. The display has shown no significant degradation over a storage life of more than 10 months and operation over 25 hours during which the display is bent over 10,000 times.     

Morphology of Oxide Particles Made by the Emulsion Combustion Method

Various oxide powders were prepared by the emulsion combustion method (ECM) using metal precursors, kerosene, and a surfactant. The product particles were characterized by transmission electron microscopy (TEM), nitrogen adsorption, and X-ray diffraction. Hollow γ-Al₂O₃ particles were produced from aluminum nitrate or chloride precursors dispersed in air, whereas dispersion of the precursor emulsion in oxygen resulted in solid α-Al₂O₃ particles. Hollow spheres were obtained also for TiO₂, ZrO₂, and Y₂O₃ by ECM of TiCl₄, zirconium oxynitrate, and yttrium nitrate in aqueous solution. A simple method was developed to predict the thickness and diameter of hollow particles using the nitrogen adsorption data and initial droplet concentration of the ECM spray. The TEM diameter and shell thickness of hollow particles were consistent with those predicted. In contrast, solid particles were formed by ECM for ZnO, Fe₂O₃, CeO₂, and MgO from aqueous solutions of their corresponding nitrates.