Docosahexaenoic Acid Esters of Hydroxy Fatty Acid Is a Novel Activator of NRF2

Fatty acid esters of hydroxy fatty acids (FAHFAs) are a new class of endogenous lipids with interesting physiological functions in mammals. Despite their structural diversity and links with nuclear factor erythroid 2-related factor 2 (NRF2) biosynthesis, FAHFAs are less explored as NRF2 activators. Herein, we examined for the first time the synthetic docosahexaenoic acid esters of 12-hydroxy stearic acid (12-DHAHSA) or oleic acid (12-DHAHOA) against NRF2 activation in cultured human hepatoma-derived cells (C3A). The effect of DHA-derived FAHFAs on lipid metabolism was explored by the nontargeted lipidomic analysis using liquid chromatography-mass spectrometry. Furthermore, their action on lipid droplet (LD) oxidation was investigated by the fluorescence imaging technique. The DHA-derived FAHFAs showed less cytotoxicity compared to their native fatty acids and activated the NRF2 in a dose-dependent pattern. Treatment of 12-DHAHOA with C3A cells upregulated the cellular triacylglycerol levels by 17-fold compared to the untreated group. Fluorescence imaging analysis also revealed the suppression of the degree of LDs oxidation upon treatment with 12-DHAHSA. Overall, these results suggest that DHA-derived FAHFAs as novel and potent activators of NRF2 with plausible antioxidant function.     

Links between Immune Cells from the Periphery and the Brain in the Pathogenesis of Epilepsy: A Narrative Review

Accumulating evidence has demonstrated that the pathogenesis of epilepsy is linked to neuroinflammation and cerebrovascular dysfunction. Peripheral immune cell invasion into the brain, along with these responses, is implicitly involved in epilepsy. This review explored the current literature on the association between the peripheral and central nervous systems in the pathogenesis of epilepsy, and highlights novel research directions for therapeutic interventions targeting these reactions. Previous experimental and human studies have demonstrated the activation of the innate and adaptive immune responses in the brain. The time required for monocytes (responsible for innate immunity) and T cells (involved in acquired immunity) to invade the central nervous system after a seizure varies. Moreover, the time between the leakage associated with blood–brain barrier (BBB) failure and the infiltration of these cells varies. This suggests that cell infiltration is not merely a secondary disruptive event associated with BBB failure, but also a non-disruptive event facilitated by various mediators produced by the neurovascular unit consisting of neurons, perivascular astrocytes, microglia, pericytes, and endothelial cells. Moreover, genetic manipulation has enabled the differentiation between peripheral monocytes and resident microglia, which was previously considered difficult. Thus, the evidence suggests that peripheral monocytes may contribute to the pathogenesis of seizures.     

Spherulitic formation and characterization of partially fluorinated copolymers and their nanohybrids with functional fillers

Poly[vinylidenefluoride‐co‐(tetrafluoroethylene)] (P(VDF‐TeFE)) exhibited clear spherulitic texture with negative birefringence. The number and growth rates of the spherulites decreased at high crystallization temperature than at low crystallization temperature. Nonetheless, overall larger spherulites were found at high crystallization temperature and the brightness of the spherulites increased very fast at low crystallization temperature, thereafter it seemed as diminution of birefringence. AFM was used to investigate the impact of organo modified nanodiamond(ND) on spherulitic textures, lamellar thickness, and thickness distribution of P(VDF‐TeFE) copolymer. Poly[ethylene‐co‐(tetrafluoroethylene)] (ETFE) also confirmed spherulites structure and the boundaries could be clearly observed. By incorporation of the organo modified nanodiamond (ND) and organo‐modified montmorillonite (MMT) in fluropolymer matrix, it was found that spherulitic texture was seriously disordered and their nanohybrids was found only to have poorly developed spherulite structure. Both of the nanohybrids samples show better crystallization temperature as compared to their neat copolymer samples. Furthermore, the incorporation of nanoparticles decreased the size of the spherulites. POLYM. ENG. SCI., 57:161–171, 2017. © 2016 Society of Plastics Engineers     

Improvement of carrier diffusion length in silicon nanowire arrays using atomic layer deposition

To achieve a high-efficiency silicon nanowire (SiNW) solar cell, surface passivation technique is very important because a SiNW array has a large surface area. We successfully prepared by atomic layer deposition (ALD) high-quality aluminum oxide (Al₂O₃) film for passivation on the whole surface of the SiNW arrays. The minority carrier lifetime of the Al₂O₃-depositedSiNW arrays with bulk silicon substrate was improved to 27 μs at the optimum annealing condition. To remove the effect of bulk silicon, the effective diffusion length of minority carriers in the SiNW array was estimated by simple equations and a device simulator. As a result, it was revealed that the effective diffusion length in the SiNW arrays increased from 3.25 to 13.5 μm by depositing Al₂O₃ and post-annealing at 400°C. This improvement of the diffusion length is very important for application to solar cells, and Al₂O₃ deposited by ALD is a promising passivation material for a structure with high aspect ratio such as SiNW arrays.     

Positive-temperature-coefficient effect of electrical resistivity below melting point of poly(vinylidene fluoride) (PVDF) in Ni particle-dispersed PVDF composites

This paper discusses the positive-temperature-coefficient effects of resistivity in Ni particle-dispersed poly(vinylidene fluoride) (PVDF) composites based on experiment results from SEM, DSC, and pressure-volume-temperature (PVT) measurements. The melting points of composites with Ni content of 20, 30, 40, and 50vol.% were equal to that of pure PVDF. The PTC effects in composites with Ni content of 40 and 50vol.% occurred at temperatures near the melting point of the PVDF matrix, whereas those in composites with Ni content of 20 and 30vol.% occurred at temperatures below the melting point of the PVDF matrix. We found that the PTC effect occurs even without melting of the matrix polymer. Moreover, we determined that a slight increase in specific volume at temperatures below the melting point of the matrix polymer acts fully as a driving force for forming a gap between fillers. This suggestion was backed up by theoretical analyses using percolation theory and a thermal-fluctuation-induced tunneling model.     

Organic–silicate hybrid catalysts based on various defined structures for Knoevenagel condensation

Two types of organic–inorganic hybrid base catalysts are prepared. Organic-functionalized molecular sieves (OFMSs), particularly “amine-immobilized porous silicates”, are designed based on common idea to immobilize catalytic active sites on silicate surface. Silicate–organic composite materials (SOCMs), such as “ordered porous silicate–quaternary ammonium composite materials”, are the precursors of ordered porous silicates obtained during the synthesis. Both the OFMS and the SOCM are used as the catalysts for Knoevenagel condensation. Among the OFMSs, there is clear tendency that the use of molecular sieve with larger pore volume and/or surface area gives the product in higher yield. Aminopropylsilyl (AP)-functionalized mesoporous silicates such as AP-MCM-41 gives the product in high yield under mild conditions. No loss of activity is observed after repeated use for three times. The SOCMs are also active for the same reaction. The precursors of the mesoporous silicates are more active than those of microporous silicates. This material can be repeatedly used without significant loss of activity. High activity is not due to the leached species. The active sites of the SOCM catalysts are considered to be SiO⁻ moieties located on the pore-mouth. Activity of the SOCM increases when the reaction is carried out without solvent, whereas decrease in activity of the OFMS is observed in the solvent-free system.     

An Approach to a Higher‐Power‐Density Power Supply for a 380‐V DC Distribution System

A methodology for realizing a higher‐power‐density DC‐DC converter has been proposed for a power unit installed in a 380‐V DC distribution system. The possibility of the converter design will be strengthened by using the series–parallel connection topology for isolated DC‐DC converters. A converter prototype with a power density of 10 W/cm³ has been fabricated, and the feasibility of the converter design has been confirmed experimentally. This result contributes to the realization of a highly efficient and highly space‐saving 380‐V DC distribution system. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 186(3): 51–62, 2014; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.22494     

Kinetics of CO2 reforming of methane by catalytically activated metallic foam absorber for solar receiver-reactors

Ni–Cr–Al metallic foam absorber with high porosity was catalytically activated using a Ru/γ-Al₂O₃ catalyst, and was subsequently tested with respect to CO₂ reforming of methane in a small-scale volumetric receiver-reactor by using a sun-simulator. A chemical storage efficiency of 37% was obtained for a mean light flux of 325 kW m⁻². Furthermore, the activity and the stability of the metallic foam absorber were compared with those of a SiC foam absorber activated with the same Ru/γ-Al₂O₃ catalyst for 50 h of light irradiation, and it was found that the metallic foam absorber has superior catalytic stability in comparison to the SiC form absorber. In addition, unlike ceramic foams such as SiC, metallic foams feature superior plasticity, which prevents the emergence of cracks caused by mechanical or thermal shock.     

Activation Energy of Aggregation-Disaggregation Self-Oscillation of Polymer Chain

In this paper, we investigated the activation energies of the aggregation–disaggregation self-oscillation induced by the Belousov-Zhabotinsky (BZ) reaction by utilizing the nonthermoresponsive polymer chain in a wide temperature range. This is because the conventional type self-oscillating polymer chain, with thermoresponsive poly(Nisopropylacrylamide) (poly(NIPAAm) main-chain covalently bonded to the ruthenium catalyst (Ru(bpy)₃) of the BZ reaction, cannot evaluate the activation energy over the lower critical solution temperature (LCST). The nonthermoresponsive self-oscillating polymer chain is composed of a poly-vinylpyrrolidone (PVP) main-chain with the ruthenium catalyst (Ru(bpy)₃). As a result, we clarified that the activation energy of the aggregation–disaggregation self-oscillation of the polymer chain is hardly affected by the concentrations of the BZ substrates. In addition, the activation energy of the nonthermoresponsive self-oscillating polymer chain was found to be almost the same value as normal BZ reaction, i.e., not including the self-oscillating polymer system with Ru moiety.