Spin-filter silicene devices induced by asymmetric electrodes

Using nonequilibrium Green's function in combination with the density functional theory, we investigate the spin-dependent transport properties of three silicene-based heterojunctions. The calculated results show that the heterojunctions are promising multifunctional devices in spintronics due to their nearly perfect bipolar spin-filter effect and high rectification ratio. Also shown are the obvious negative differential resistance behaviors for both spin channels. By analyzing the spin-resolved transmission spectra and the band structure of ZSiNR electrodes, as well as the spatial resolved local density of states, the mechanisms for these intriguing properties are demonstrated in detail.     

High triplet,bipolar polymeric hosts for highly efficient solution-processed blue phosphorescent polymer light-emitting diodes

Two polymeric hosts PCzTPP and PCzTPPO with twisted geometrical configurations for blue phosphorescent polymer light-emitting diodes (PhPLEDs) were designed and synthesized by incorporating electron-accepting carbazole units with electron-donating TPP/TPPO groups. This molecular design endows PCzTPP and PCzTPPO with high glass transition temperatures of 204 °C and 215 °C, high triplet energies of 2.72 eV and bipolar features. In addition, the HOMO and LUMO of these polymers matched well with the HOMO of the hole-transport layer and the Fermi level of cathode compared with PVK, which facilitated the injection of holes and electrons. PCzTPP- and PCzTPPO-based single-emissive-layer blue PhPLEDs were fabricated with simplified device configuration by solution process using FIrpic as a dopant. These devices exhibited lower turn on voltages (<8 V) than PVK-based devices (12 V). The maximum luminances of PCzTPP- and PCzTPPO-based devices were twofold and threefold that of PVK-based devices, and the maximum current efficiencies were nearly threefold and ninefold, respectively. Moreover, PCzTPPO-based solution processed blue PhPLEDs with improved configuration showed maximum current efficiency and external quantum efficiency of 14.5 cd/A and 6.6%, respectively.     

Effect of P on glass forming ability,magnetic properties and oxidation behavior of FeSiBP amorphous alloys

The effect of P on the glass forming ability, soft magnetic properties and oxidation behavior of Fe₇₈B₁₃Si_9-xP_x (x = 0–7) amorphous alloys were investigated. It is found that the proper introduction of P, can effectively improve the glass forming ability and stability of supercooled liquid region. Fe₇₈Si₄B₁₃P₅ BMG, which exhibits high saturation flux density of 1.56 T, was readily made into rod sample with a diameter of 1.5 mm under air casting atmosphere. P bearing alloys also exhibit excellent soft magnetic properties containing low coercivity of 1.7–2.7 A/m, and high effective permeability of 8200–12,200. Slight oxidation can further improve the coercivity to a lower value of 1.1 A/m and the higher effective permeability to 11,900 for the alloys with P content no more than 3 at. %. Excessive addition of P may deteriorate the glass forming ability, soft magnetic properties and oxidation behavior. Magnetic domain revealing the magnetization process of the amorphous ribbons were characterized to explain the effect of P on magnetic properties and oxidation behavior.     

Simulation research on the influence of eroded primary key strata on dynamic strata pressure of shallow coal seams in gully terrain

In Huojitu Coal Mine of Shendong mining area,the dynamic strata pressure (DSP) accidents occurred when the working faces passed the gully terrain,Focusing on this problem,we used physical simulation ex...     

大数据流式计算框架Heron环境下的流分类任务调度策略

新型大数据流式计算框架Apache Heron默认使用轮询调度算法进行任务调度，忽略了拓扑运行时状态以及任务实例间不同通信方式对系统性能的影响。针对这个问题，提出Heron环境下流分类任务调度策略（DSC-Heron），包括流分类算法、流簇分配算法和流分类调度算法。首先通过建立Heron作业模型明确任务实例间不同通信方式的通信开销差异；其次基于流分类模型，根据任务实例间实时数据流大小对数据流进行分类；最后将相互关联的高频数据流整体作为基本调度单元构建任务分配计划，在满足资源约束条件的同时尽可能多地将节点间通信转化为节点内通信以最小化系统通信开销。在包含9个节点的Heron集群环境下分别运行SentenceWordCount、WordCount和FileWordCount拓扑，结果表明DSC-Heron相对于Heron默认调度策略，在系统完成时延、节点间通信开销和系统吞吐量上分别平均优化了8.35%、7.07%和6.83%；在负载均衡性方面，工作节点的CPU占用率和内存占用率标准差分别平均下降了41.44%和41.23%。实验结果表明，DSC-Heron对测试拓扑的运行性能有一定的优化作用，其中对接近真实应用场景的FileWordCount拓扑优化效果最为显著。     

Controllable memristive patterns in poly(9,9-dioctylfluorene)-based sandwich device

Currently, there are two prevalent types of I-V memristive patterns for memristive applications, 0-type and 8-type hysteresis loop, and their respective characteristics result in their specific applications in different situations, such as data storage and neuromorphic computing. In spite of the abundant achievements of these remarkable performances, scarce works are specially concerned about the relations and regulations between them for persuing the multiple functions in a single element, and an ideal platform with both the achievements and controllable transformations has been rarely reported. Herein, the novel organic material—poly(9,9-dioctylfluorene) (PFO) is utilized to construct the sandwich prototype. The electrical transporting properties are systematically investigated through particular programming protocols. The 0-type and 8-type memristive patterns are successfully obtained during low and high voltage sweeps, respectively. Then the sectionalized fitting results of the current curves, the carrier transporting behaviors as well as the regulations of device energy levels are associatively demonstrated to analyze the electrical activity-dependent transformations between different memristive patterns. More importantly, the appearance of the 8-type hysteresis loop can be regulated by the rectification property, and the rectification can be largely enhanced by the reconfiguration of device energy levels. Consequently, for the versatile memristive device, based on the 0-type hysteresis, it can serve as a data storage or artificial synapse element, and the rectification-modified memristive behaviors can effectively impede the unintended sneak current paths for high-density integration.     

Effect of sintering temperature on mechanical properties of magnesia partially stabilized zirconia refractory

The optimized sintering conditions for a 3.5 wt% magnesia partially stabilized zirconia (Mg-PSZ) refractory were proposed in our recent research. The influence of the sintering temperature on the development of phase composition, microstructure, densification, thermal expansion and mechanical strength was studied in detail by X-ray diffraction (XRD), scanning electron microscope (SEM), He-pycnometer, high temperature dilatometry and three-point bending test. The samples sintered at 1670 °C had the highest bend strength, the maximum densification, the lowest thermal expansion coefficient (CTE), a homogeneous microstructure and a linear change in thermal expansion.     

Cu-MOF assisted synthesis of CuS/CdS(H)/CdS(C): Enhanced photocatalytic hydrogen production under visible light

CuS/CdS(H)/CdS(C) photocatalysts were synthesized via the hydrothermal method by employing thiourea, Cd(CH₃COO)₂·3H₂O and copper 1,4-benzenedicarboxylate MOF (CuBDC). The photocatalysts were characterized by XRD, XPS, BET, TEM and UV–vis diffuse reflectance spectra. Interestingly, hexagonal CdS (CdS(H)) and cubic CdS (CdS(C)) were formed with phase junctions in one step when CuBDC was introduced in the synthesis process, in addition, CuS nanoparticles were deposited on CdS. However, only hexagonal CdS was obtained without CuBDC. It demonstrated that CuBDC was not only the precursor of CuS but also the structural modifier for CdS. With the reduction of re-combination of photo-induced electrons and holes caused by phase junctions and the enhancement of visible-light absorptions due to the loading of CuS, all CuS/CdS(H)/CdS(C) photocatalysts had higher photocurrent densities under visible-light irradiation, and consequently the higher rates of H₂ production than pure CdS(H). Typically, the catalyst with 2.89 wt% of Cu showed a highest rate of H₂ evolution at 2042 μmol/g/h.     

Three-dimensional viscous flow and heat transfer over a permeable shrinking sheet

This paper presents a numerical analysis of a steady three-dimensional fluid flow and heat transfer towards a permeable shrinking sheet. The governing nonlinear partial differential equations are transformed into a system of ordinary differential equations by a similarity transformation, which are then solved numerically by a shooting method. The effects of the governing parameters on the skin friction and heat transfer from the surface of the shrinking surface are illustrated graphically. It is found that dual solutions exist for the shrinking case. A comparison with known results from the open literature has been done and it is shown to be in excellent agreement.