Microstructures and Mechanical Properties of Solid-State Welded Steels.

This study aimed to evaluate the soundness of solid-state welded steels. STS 430F alloy with a rod type was selected as experimental material, and the friction welding was conducted at a rotation speed of 2,000 RPM and upset length of 3 mm. The application of friction welding on STS 430F rods led to significant grain refinement in the welded zone (1.3 µm) compared to that observed in the base material (16.8 µm). The refined grains in the welds contributed to the development of the mechanical properties. In particular, the Vickers microhardness was increased by approximately 25% compared to the base material, and the fracture at the tensile specimen of the welds occurred at the base material zone and not in the welded zone, which suggests a soundly welded state on the STS 430F rods.

High transmittance and deep RGB primary electrochromic color filter for high light out-coupling electro-optical devices.

We report a transmittance controllable electrochromic color filter (TCECF) by incorporating new electrochromic leuco dyes and their optimized composition. Each primary color red (R), green (G), and blue (B) electrochromic filter has an excellent transmittance of more than 84% at 650 nm, 540 nm, 450 nm, and the color coordinates are controllable from white (0.332, 0.347) to deep-red (0.621, 0.344), deep-green (0.327, 0.646), and deep-blue (0.179, 0.085), respectively. Also, each TCECF has good coloration efficiencies of 188.7 cm2 C-1 (R), 189.3 cm2 C-1 (G), and 147.8 cm2 C-1 (B) with high optical density change. A full color producible electrochromic color filter (ECF) is designed and fabricated by integrating primary RGB color filters with a refractive index matching adhesive layer. The fabricated three-stack full color producible ECF enables high transmittance of about 61% for clear white light extraction, and it can produce various colors including RGB. This TCECF technology will be very useful for high light out-coupling electro-optical applications, such as smart lighting, smart window, and display.

An accurate measurement of the dipole orientation in various organic semiconductor films using photoluminescence exciton decay analysis.

In this study, we report an accurate and more reliable approach to estimate the dipole orientation of emitters especially phosphorescence, fluorescence and even thermally activated delayed fluorescence. The dipole orientation measurements are performed by examining the variation of the photoluminescence (PL) exciton decay rate from time-resolved PL and optical analysis. Our anisotropic dipole orientation results are consistent with those of previous reports. The studied measurement approach is very reliable and accurate to estimate the dipole orientation of any organic semiconductor materials regardless of whether they are doped or neat films.

Highly efficient single-stack hybrid cool white OLED utilizing blue thermally activated delayed fluorescent and yellow phosphorescent emitters.

Highly efficient single-stack hybrid cool white organic light-emitting diodes (OLEDs) having blue-yellow-blue multiple emitting layers (EMLs) are designed and constructed by utilizing blue thermally activated delayed fluorescent (TADF) and yellow phosphorescent emitters. The out-coupling efficiencies of yellow and blue emissions are maximized by tuning the ITO and total device thickness that satisfies both of antinode positions for yellow and blue emissions in a limited multiple EML thickness. To obtain a cool white emission, the exciton formation ratio in the blue-yellow-blue multiple EML system is controlled by manipulating the recombination zone through charge conductivity variation of host medium in the blue TADF EML. The resulting device exhibits cool white emission with very high maximum external quantum efficiency of 23.1% and CIE color coordinates of (0.324, 0.337). We anticipate that the studied approach will raise the viability of single-stack hybrid cool white OLEDs for high performance display applications.

Next generation smart window display using transparent organic display and light blocking screen.

Transparent organic light emitting diodes (TOLED) have widespread applications in the next-generation display devices particularly in the large size transparent window and interactive displays. Herein, we report high performance and stable attractive smart window displays using facile process. Advanced smart window display is realized by integrating the high performance light blocking screen and highly transparent white OLED panel. The full smart window display reveals a maximum transmittance as high as 64.2% at the wavelength of 600 nm and extremely good along with tunable ambient contrast ratio (171.94:1) compared to that of normal TOLED (4.54:1). Furthermore, the performance decisive light blocking screen has demonstrated an excellent optical and electrical characteristics such as i) high transmittance (85.56% at 562nm) at light-penetrating state, ii) superior absorbance (2.30 at 562nm) in light interrupting mode, iii) high optical contrast (85.50 at 562 nm), iv) high optical stability for more than 25,000 cycle of driving, v) fast switching time of 1.9 sec, and vi) low driving voltage of 1.7 V. The experimental results of smart window display are also validated using optical simulation. The proposed smart window display technology allows us to adjust the intensity of daylight entering the system quickly and conveniently.

Ligularia fischeri extract attenuates liver damage induced by chronic alcohol intake.

Context Ligularia fischeri (Ledebour) Turcz. (Compositae) has been used as a leafy vegetable and in traditional medicine to treat hepatic disorder in East Asia. Objective The present study explores the antioxidant activity of LF aqueous extract on EtOH-induced oxidative stress accompanied by hepatotoxicity both in vitro and in vivo. Materials and methods In vitro study using the mouse liver NCTC-1469 cell line was conducted to estimate the cytotoxicity as well as the inhibitory effect of LF extract against alcohol-treated cell damage. In vivo study used an alcohol-fed Wister rat model orally administered EtOH (3.95 g/kg of body weight/d) with or without LF extract (100 or 200 mg/kg body weight) for 6 weeks. Serum and liver tissue were collected to evaluate hepatic injury and antioxidant-related enzyme activity. Results The EC50 value for the DPPH radical scavenging capacity of LF extract was 451.5 µg/mL, whereas the IC50 value of LF extract in terms of EtOH-induced reactive oxygen species (ROS) generation was 98.3 µg/mL without cell cytotoxicity. LF extract (200 mg/kg body weight) significantly reduced the triglyceride content of serum (33%) as well as hepatic lipid peroxidation (36%), whereas SOD activity was elevated three-fold. LF extract suppressed expression of CYP2E1 and TNF-α, and attenuated alcohol-induced abnormal morphological changes. Discussion and conclusion LF extract attenuated liver damage induced by alcoholic oxidative stress through inhibition of ROS generation, down-regulation of CYP2E1, and activation of hepatic antioxidative enzymes. Homeostasis of the antioxidative defence system in the liver by LF extract mitigated hepatic disorder following chronic alcohol intake.

Novel hole transporting materials based on 4-(9H-carbazol-9-yl)triphenylamine derivatives for OLEDs.

During the past few years, organic light emitting diodes (OLEDs) have been increasingly studied due to their emerging applicability. However, some of the properties of existing OLEDs could be improved, such as their overall efficiency and durability; these aspects have been addressed in the current study. A series of novel hole-transporting materials (HTMs) 3a-c based on 4-(9H-carbazol-9-yl)triphenylamine conjugated with different carbazole or triphenylamine derivatives have been readily synthesized by Suzuki coupling reactions. The resulting compounds showed good thermal stabilities with high glass transition temperatures between 148 and 165 °C. The introduction of HTMs 3b and 3c into the standard devices ITO/HATCN/NPB/HTMs 3 (indium tin oxide/dipyrazino(2,3-f:2',3'-h)quinoxaline 2,3,6,7,10,11-hexacarbonitrile/N,N'-bis(naphthalen-1-yl)-N,N'-bis(phenyl)-benzidine/HTMs)/CBP (4,4'-Bis(N-carbazolyl)-1,1'-biphenyl): 5% Ir(ppy)3/Bphen/LiF/Al (tris[2-phenylpyridinato-C2,N]iridium(III)/4,7-diphenyl-1,10-phenanthroline/LiF/Al) resulted in significantly enhanced current, power, and external quantum efficiencies (EQE) as compared to the reference device without any layers of HTMs 3.

An efficient nano-composite layer for highly transparent organic light emitting diodes.

We report highly transparent and low resistive new cathode structures, which basically consist of nano-composite layer/Ag/WO3 for transparent organic light-emitting diode (TOLED) applications. Our new cathode structure exhibits an extremely high transmittance of 91.2% at 550 nm, a low sheet resistance of 5.4 Ω â–¡(-1), and excellent electron injection properties. Such a high transmittance along with a low resistivity of the fabricated new cathode could be explained by surface-modifying behavior with the generation of a nano-composite thin silver oxide layer during Ag deposition. Chemical interaction at the interface between the electron injection layer and the electron transport layer results in good electron injection properties in TOLEDs. The fabricated TOLEDs with our new cathode structures have a full device transmittance of 85-87% at 550 nm.