Donor–acceptor-structured 1,4-diazatriphenylene derivatives exhibiting thermally activated delayed fluorescence: design and synthesis,photophysical properties and OLED characteristics

A new series of luminescent 1,4-diazatriphenylene (ATP) derivatives with various peripheral donor units, including phenoxazine, 9,9-dimethylacridane and 3-(diphenylamino)carbazole, is synthesized and characterized as thermally activated delayed fluorescence (TADF) emitters. The influence of the donor substituents on the electronic and photophysical properties of the materials is investigated by theoretical calculations and experimental spectroscopic measurements. These ATP-based molecules with donor–acceptor–donor (D–A–D) structures can reduce the singlet–triplet energy gap (0.04–0.26 eV) upon chemical modification of the ATP core, and thus exhibit obvious TADF characteristics in solution and doped thin films. As a demonstration of the potential of these materials, organic light-emitting diodes containing the D–A–D-structured ATP derivatives as emitters are fabricated and tested. External electroluminescence quantum efficiencies above 12% and 8% for green- and sky-blue-emitting devices, respectively, are achieved.     

Preparation of Alumina Fiber-Reinforced Aluminum by Squeeze Casting and Their Machinability

Alumina fiber-reinforced aluminum alloy composites were prepared by squeeze casting, and the effect of the reinforcement on the machinability of the alloy was investigated. Two kinds of short alumina fibers, which have the same fiber size but different hardness, were used. Preform in which the fibers were in a random arrangement was formed with SiO₂ binder, and then was infiltrated with the alloy melt to prepare the composite. The fiber–matrix interfacial bond via the binder is sufficient and no reaction product was detected. The cutting force of the alloy was reduced by the fiber-reinforcement. The lower the hardness of the fiber in the composite, the lower the cutting force of the composite. The roughness of the machined surface was drastically decreased by the reinforcement. Observation of the chip formed on the machined surface indicated that the fiber suppressed the formation of the built-up-edge, and this fact would lead to the reduction in the surface roughness by the reinforcement. The chips were shortened by the reinforcement. The difference in hardness of the alumina fiber hardly affected the roughness and the chip morphology. The hardness of the fiber has a strong effect to decrease the tool life.     

Control of the coating layer thickness of TiO2–SiO2 core–shell hybrid particles by liquid phase deposition

This paper describes control of the coating layer thickness and the crystallite size of the core–shell hybrid particles by controlling the process parameter. The core–shell hybrid particles were prepared using liquid phase deposition (LPD). We confirmed that the homogeneous coating was attained from the result of the zeta potential and the transmission electron microscope (TEM) observation. Furthermore, the coating layer microstructure was estimated using Brunauer–Emmett–Teller (BET) method. The obtained coating layer of titania was estimated using the band gap energy. Results indicate that the blue shift of the band gap energy signifies that the physical property of the hybrid particles was controlled by the coating layer thickness and the crystallite size, which are determined by the processing parameters.     

Strain-mediated phase control and electrolyte-gating of electron-doped manganites

A prototype Mott transistor, the electric double layer transistor with a strained CaMnO(3) thin film, is fabricated. As predicted by the strain phase diagram of electron-doped manganite films, the device with the compressively strained CaMnO(3) exhibits an immense conductivity modulation upon applying a tiny gate voltage of 2 V.     

Influence of different feeding systems on the growth performance and muscle development of Japanese Black steers

This study investigated the growth performance and gene expression for muscle development between grass hay-fed (GH) and concentrate-fed (CT) steers. Daily gain and energy intake during the fattening period of the GH group were lower than those of the CT group. Analysis of C/EBPα, PPARγ2, myosin heavy chain (MHC), and myostatin gene expressions was performed by real-time PCR. Expressions of C/EBPα and myostatin in semitendinosus and longissimus lumborum (LL) muscles were higher in the CT group than in the GH group at the end of fattening. In LL muscle, MHC expression at the end of fattening was greater in the GH group than in the CT group. These results suggest that regulation of adipogenesis and myogenesis by the expression of genes involved in muscle development might have occurred in the skeletal muscle of the GH group by the feeding of grass hay and/or because of the low energy intakes.     

Transforming growth factor-beta inhibits interferon-gamma secretion by lymphokine-activated killer cells stimulated with tumor cells

The effect of transforming growth factor-beta (TGF-beta) secreted by glioblastoma (T98G) cells on the secretion of interferon-gamma (IFN-gamma) by lymphokine-activated killer (LAK) cells stimulated with tumor cells was investigated in cocultures of LAK and Daudi cells supplemented with T98G culture supernatant, T98G culture supernatant preincubated with anti-TGF-beta 1 and anti-TGF-beta 2 neutralizing antibodies, anti-TGF-beta 1 and anti-TGF-beta 2 antibodies, or natural human TGF-beta 1 or recombinant human TGF-beta 2. LAK cells were incubated with anti-TGF-beta 1 and anti-TGF-beta 2 antibodies, and with T98G cells of which the supernatant contained both active and latent forms of TGF-beta 1 and TGF-beta 2, with or without neutralizing antibodies. Addition of the supernatant from T98G cells to LAK/Daudi culture caused inhibition of IFN-gamma secretion by LAK cells. The inhibition was abolished by pretreatment of the supernatants with anti-TGF-beta antibodies. Addition of TGF-beta 1 and TGF-beta 2 to the LAK/Daudi culture inhibited IFN-gamma secretion by LAK cells in a dose-dependent manner. Addition of anti-TGF-beta antibodies to the LAK culture resulted in increased IFN-gamma secretion. T98G cells failed to stimulate LAK cells to secrete more IFN-gamma. Addition of anti-TGF-beta antibodies to the LAK-T98G culture resulted in increased IFN-gamma secretion by LAK cells. These results suggest that most malignant glioma cells which secrete high levels of TGF-beta can inhibit IFN-gamma secretion by LAK cells even after tumor cell stimulation.     

Recrystallization and precipitation behavior of low-activation V-Cr-Ti alloys after cold rolling

Recrystallization and precipitation behavior after cold working were investigated for three V-4Cr-4Ti alloys, NIFS-HEAT-1, NIFS-HEAT-2 and US 832665, which contain different levels of impurities. The decrease in hardness and the initiation of recrystallization against test temperature do not depend on the oxygen level. However, the rate of grain growth decreased with the increase in the impurity levels. Bimodal distribution of the precipitates was observed after annealing at 1273 K. The large precipitates were Ti-rich precipitates, and the small ones were composed mainly of Ti, C and O (Ti-C-O precipitates). The impurities were dissolved from Ti-C-O precipitates above 1273 K, and the level of impurities in the matrix increased and resulted in the increase in the hardness. Based on the results, the annealing temperature for V-4Cr-4Ti alloys is recommended not to exceed 1273 K for the purpose of maintaining good mechanical properties such as tensile and impact properties.     

Development of Nanoscale Temperature Measurement Technique Using Near-field Fluorescence

A nanoscale thermal system design, especially for the precise measurement of the temperature distribution in microfabricated devices using novel nanomaterials such as carbon nanotubes and fullerene has become increasingly important along with the development of nanotechnology. A new approach has been proposed toward an optical nanoscale temperature measurement method using near-field optics and fluorescence thermometry, namely, Fluor-NOTN (fluorescent near-field optics thermal nanoscopy). The topographic image and temperature dependence of a fluorescently modified sample, excited by near-field light, are simultaneously monitored. In this article, the temperature dependence of Cy3 fluorescent dye is verified near room temperature (298–308 K). A Cy3 mono-dispersed sample of a permalloy (Ni₈₁Fe₁₉) wire heater, 500 nm in width and 100 nm in thickness, is designed and fabricated. A localized temperature gradient of ΔT = 4 K within a submicron distance from the heater was successfully detected by near-field fluorescence with 100 nm spatial resolution.