The primary arylamines reacted with arylhalides to give the secondary arylamines by the catalysis of Pd(dba)2/P(f-Bu)3 at 80℃ in toluene. The secondary arylamines reacted with bromoanthrancenes to afford the organic light emitting diode materials of aminoanthrancene type by the catalysis of Pd(Oac)...
100 mol% activator orthorhombic Tb 2 (MoO 4 ) 3 green phosphors were prepared using a solid-state reaction method. The impact of sintering temperature on the crystalline phase structures, the compositions, the sizes and morphologies of particles, the values of energy bandgap ([Formula: see text][Formula: see text]), the photoluminescence (PL) excitation and emission spectra, the fluorescence lifetimes, PL quantum yield (PLQY), and the luminescent thermal stabilities of the prepared material were comprehensively investigated. The particle size increased from 2.54 to 5.81 [Formula: see text]m and the [Formula: see text][Formula: see text] decreased from 3.60 to 3.41 eV with the calcine temperature increased from [Formula: see text] to [Formula: see text]. The Tb 2 (MoO 4 ) 3 green phosphor prepared at [Formula: see text] exhibited optimal PL intensity though it did not possess the highest PLQY with 380 nm excitation. Moreover, the sample prepared at [Formula: see text] showed better thermal stabilities than that prepared at [Formula: see text]. The research proved the sintering temperature has great effects on the properties of Tb 2 (MoO 4 ) 3 phosphors.
Abstract Microstructures are applied in various fields to improve the friction and lubrication of mechanical components. Through-mask electrochemical etching (TMEE) has shown good feasibility in machining microstructures array. However, the machining precision of microstructures gradually decreases with increasing etching depth in TMEE. Localization and uniformity are essential indicators of machining precision in TMEE. Herein, particle assisted through-mask electrochemical etching (PA-TMEE) method was proposed to improve the localization and uniformity. Firstly, a coupled multi-physical field model, including gas-liquid two-phase flow, particle motion, and electrochemical processes, was established and adopted to predict the profiles of micro pits. Secondly, a comparison experiment between PA-TMEE and traditional TMEE was performed. The experimental results show that using PA-TMEE instead of TMEE resulted in improved localization and uniformity of the micro pits array. Then, the paper analyzed the effect of particle diameter and content on micro pits. When the particle diameter was 40 µm, and the particle content was 6 g/L, the maximum etching factor was 2.4. The minimum coefficient of variation of the diameter and depth of micro pits were 3.3% and 5.2%. Finally, The machining mechanism of PA-TMEE was analyzed by Scanning Electron Microscopy and Energy Dispersive Spectrometer.
Background: The collection of temperature is very important in life. Thermistor temperature sensors are an important part of the temperature acquisition system. Thermistor temperature sensors can convert the temperature signal into an electrical signal for output. Due to the different application fields and technical requirements, the shape, function and structure of thermistor temperature sensors are very different. Objective: The purpose of this study is to summarize and analyze the advantages and disadvantages of various devices from a large number of documents and patents. Methods: In this paper, the patents and the latest research of thermistor temperature sensors are reviewed. Results: By summarizing the characteristics of a large number of thermistor temperature sensors and analyzing the problems, the development of thermistor temperature sensors is expected. Conclusion: Thermistor temperature sensors are widely used. Therefore, it is necessary to carry out special structural design and technical research for thermistor temperature sensors in different application fields. At the same time, with the development of technology, intelligent sensors and multi-functional sensors are an inevitable development trend.
The ground fissure is one of primary geological disasters in Xi’an, China. The extension pattern and deformation failure area near fissure are studied through the FEM of elastic-plastic fracture mechanics in this paper. The results show the crack extension is not completely tension crack, it is mixed mode when the confined aquifer was pumped. The extents of earth surface deformation and stress concentration of beyond plate are larger than that of the bottom one. It is consistent with observational results.
Sealing aerodynamic characteristics are affected by the seal structure, and thus the stability of the rotor system is affected too. A 1.5-stage, three-dimensional, full-cycle model of the high-pressure cylinder of a 1000 MW steam turbine was established. The high eccentricity whirl of the rotor was realized using mesh deformation technology and the multi-frequency whirl model. The nonlinear steam-flow-exciting force of different sealing structures was obtained using CFD/FLUENT, and the motion equations with a nonlinear steam-exciting force were solved using the Runge–Kutta method. The motion characteristics and stability of the rotor system with different sealing structures were obtained. The results show that there are “inverted bifurcation” and “double bifurcation” phenomena in the bifurcation diagrams of different tooth numbers, boss numbers, and tooth lengths, and a 1/2 power frequency of different sealing structures goes through the process of weakening, disappearing, reproducing, and evolving into a 1/3 power frequency and a 2/3 power frequency. With the increasing load, the steam-flow-exciting force becomes stronger, and the multi-frequency vibration and dense frequency phenomena are significant. Under some load conditions, the change curves of three kinds of teeth in 1/3 and 2/3 power frequency vibrations are highly similar, and the tooth number has little influence on the system stability. Under the high load condition, with the boss number increasing, the chaos phenomenon is weakened. Increasing the tooth length is beneficial to the stability of the rotor.
To achieve sustainable development during urbanization, construction waste is recycled for use as an aggregate in recycled concrete (RC). To determine the influence of the brick content in coarse recycled aggregates on the damage sustained by the resultant RC, the RC was first divided into seven phases: natural crushed stone, old gravel inside waste concrete, bricks, new mortar, old mortar on waste concrete surfaces, and new and old interface transition zones. The Monte Carlo method was then applied to establish a two-dimensional random aggregate model of the RC made with coarse brick aggregates. The ABAQUS software package was used to simulate a uniaxial compression test, the results of which were combined with those of a macro-test to determine the internal damage change rule of brick-containing RC. The stress–strain curves obtained from the simulation coincided well with that of the macroscopic tests. As the brick content increased, the damage zone inside the specimen and the number of microcracks increased. The stress concentration area decreased, as indicated by a lower compressive strength in the macro-test. The results indicate that higher brick contents in RC yield more initial damage inside the concrete and a lower compressive strength.
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