Microstructure,interfacial characteristics,and wear performances of Cu–Fe–SiC cermet composites

The Cu–Fe metal-based ceramic grinding wheel material with SiC as abrasive was prepared by the powder metallurgy process of ball milling and hot pressing sintering. Cu–Fe–SiC cermets with Cu:Fe mass ratios of 4:1, 1:1, and 1:4 were designed by changing the composition of metal binder. The phase composition, microstructure, mechanical properties, and grinding properties of Cu–Fe–SiC cermets were systematically studied. The effect of Cu–Fe binder ratio on the microstructure and properties of cermets was analyzed. The results show that with the increase of Fe content, the density and hardness of cermets increase gradually, indicating that the mechanical properties are improved. Because the Fe in the adhesive can react with the abrasive SiC to form the reaction bonding interface, the Cu–80Fe–SiC cermets with higher Fe content have better adherence. The grinding test results of Cu–80Fe–SiC cermet show that the friction coefficient is .341, the surface roughness is 6.64 μm, the residual stresses parallel to the grinding direction are 353.3 MPa, and the residual stresses perpendicular to the grinding direction are 140.9 MPa. With the increase of Fe content, the wear mechanism changes from ploughing and cutting to friction.     

Effects of Sm-substitution on dielectric,ferroelectric, and piezoelectric properties of 0.36(Bi1-xSmx)ScO3-0.64PbTiO3 ceramics

Dielectric, ferroelectric, and piezoelectric properties of 0.36(Bi_1-xSm_x)ScO₃-0.64PbTiO₃ (BSPT-xSm) ceramics were investigated to assess effects of Sm-substitution on 0.36BiScO₃-0.64PbTiO₃ for high temperature piezoelectric device application. Optimal sintering was achieved at 1200°C when the BSPT-xSm ceramics were fully densified and crystallized with a perovskite structure without any secondary phase. The substitution of Bi³⁺ with Sm resulted in degradation of rhombohedral side in BSPT-xSm ceramics having morphotropic phase boundary. In addition, variations of grain size and ferroelectric behavior after Sm-substitution were insignificant. However, dielectric constant (ε^T₃₃/ε₀) was significantly enhanced with an increasing of amount of Sm to 5%. Although a slight decrease of relative density in case of x exceeding 3% led to deterioration of piezoelectric values of d₃₃, k_p, and d₃₃*, the BSPT-3%Sm ceramic exhibited excellent values of d₃₃ of 628 pC/N, k_p of 62.4%, and d₃₃* of 718 pm/V at 4.5 kV/mm, along with a high ferroelectric transition temperature of 421°C. The highly increased diffusion coefficient of 1.909 also implies that the Sm-substitution contributed to relaxor-like ferroelectric behavior of BSPT ceramics.     

Rational Ligand Design of Heteroleptic Iridium (III) Complexes toward Nearly Perfect Horizontal Dipole Orientation for Highly Efficient Red-Emitting Phosphorescent Organic Light-Emitting Diodes

The horizontal orientation of the transition dipole moment of the phosphorescent emitters is understood to be an important factor to enhance the external quantum efficiency (EQE) of organic light-emitting diodes by improving light out-coupling in optical microcavity structures. Here, red-emitting heteroleptic iridium (III) complexes exhibiting an extremely high horizontal ratio of emitting dipole orientation (EDO) and photoluminescence quantum yield (PLQY), as well as longer device operational lifetime, without scarifying any other photophysical properties are reported. The systematic molecular design of main and ancillary ligands in heteroleptic iridium complexes leads to the achievement of both a horizontal EDO of 92% and a PLQY of 98% in the red-emitting phosphorescent devices along with a shorter exciton decay time of 0.71 µs. Accordingly, the red-emitting devices show excellent performances of maximum EQE of 32% and low-efficiency roll-off with the 1931 Commission Internationale de L′Eclariage coordinates of (0.66, 0.34). Therefore, this approach opens the way for further development of new red-emitting iridium complexes pushing the device efficiency toward the theoretical limits.     

3D simulation of hydrogen distributions affected by a passive auto-catalytic recombiner in an oxygen-starved condition

In this paper, we simulated the change in hydrogen behavior according to a Passive Autocatalytic Recombiner (PAR) under oxygen depletion conditions and compared the results with the THAI project experimental results. In order to reduce calculation cost, we calculated the hydrogen-oxygen bonding reaction in the catalyst region through correlation equations of the hydrogen removal rate according to the PAR type, and we did not consider the shape of the catalyst with a relatively small size and the detailed hydrogen-oxygen bonding reaction. The hydrogen concentration at the PAR inlet and outlet, mixed gas temperature, flow rate at PAR inlet, pressure and total hydrogen removal rate were similar to the experimental results and analysis values in all cases and the reduction in the hydrogen removal rate agreed well under oxygen depletion conditions. However, after the hydrogen injection was stopped, errors of the hydrogen concentration and flow rate at the PAR inlet increased as the buoyancy decreased because the high temperature of the catalyst was not taken into account.     

An experimental mining and analytics for discovering proportional process patterns from workflow enactment event logs

Wireless Networks - In this paper, we carry out an experimental analytics to show how much perfectly the conceptual mining framework is operable on re-discovering workflow process patterns and...     

High Triplet Energy Hosts for Blue Organic Light-Emitting Diodes

Blue organic light-emitting diodes (OLEDs) have been a bottleneck for OLEDs lighting and flexible displays. Improving the operational lifetimes and simultaneously decreasing efficiency roll-off while maintaining high quantum efficiency is currently a challenge in the scientific community and industry. Optimizing the fabrication process of devices and developing stable and efficient luminescence and transporting materials and developing host materials with high triplet energy is an effective way to overcome this obstacle. On the one hand, the host material can disperse the blue emitters to reduce the possibility of exciton annihilation. On the other hand, it can adjust the carrier transport, exciton formation, and energy transfer in the device. In recent years, many efforts have been undertaken for the design, synthesis, and applications of the novel host. A systematic summary and comments on the recent advances of high triplet energy hosts for blue OLEDs are provided here, which specifically include bipolar transport hosts, single thermally activated delayed fluorescence (TADF) hosts, TADF assistant hosts, exciplex hosts, exciplex free type mixed hosts, and electroplex hosts. Moreover, future prospects for host for high performance blue OLEDs are also proposed.     

Thermal conductivity of plasma-enhanced atomic layer deposited hafnium zirconium oxide dielectric thin films

Hafnium zirconium oxide (HZO) is promising for applications in future memory devices and energy storage and harvesting. While many studies have focused upon the dielectric and structural properties of HZO, much less investigated are their thermal properties, particularly in thin-film form. We present the first report on the thermal conductivity of plasma-enhanced atomic layer deposited (PEALD) HZO thin films. Steady-state thermoreflectance measures the effective thermal conductivity of undoped and yttrium-doped HZO films and their interfaces. The effective thermal conductivity of the undoped film is found to be 0.75 W m^–1 K^–1, which is comparable to those reported previously for thermal ALD HZO films with similar composition. With increasing yttrium doping level, the effective thermal conductivity slightly decreases down to 0.67 W m^–1 K^–1 owing to dopant scattering of phonons. Our PEALD HZO films are nanocrystalline as observed by grazing-incidence X-ray diffraction and transmission electron microscopy.     

History table-based linear analysis method for DRAM-PCM hybrid memory system

The Journal of Supercomputing - This research is to design a history table-based linear analysis method for a DRAM-PCM (phase change memory) hybrid memory system supporting irregular and complex...     

Fabrication of platinum-doped WS2 hollow spheres catalyst for high-efficient hydrogen evolution reaction

Journal of Applied Electrochemistry - In this study, tungsten disulfide (WS2) was synthesized by a facile one-step hydrothermal method, and an excellent hydrogen evolution reaction (HER) catalyst...     

Optimizing extraction conditions for functional compounds from ginger (Zingiber officinale Roscoe) using response surface methodology

Food Science and Biotechnology - Extraction process was optimized for maximizing the contents of functional compounds from ginger using response surface methodology which applied Box–Behnken...