The effect of substrate temperature on the microstructure and tunnelling magnetoresistance of FeCo–Al2O3 nanogranular films

A series of FeCo–Al₂O₃ granular films were prepared with a magnetron controlled sputtering system. The magnetic–transport properties and microstructure of films sputtered at various substrate temperatures were characterized by conventional four probes method, SQUID magnetometer, analytical electron microscope and transmission electron microscope, respectively. The results indicate that the tunnelling magnetoresistance reaches the peak value of about 6.9% for FeCo (41 vol.%)-Al₂O₃ granular films sputtered at 300 K, while for FeCo granular films sputtered at 473 K, the 6% peak value in tunnelling magnetoresistance vs. volume fraction curve displaces toward the lower FeCo content of about 35 vol.%. Meanwhile, FeCo (30vol.%)-Al₂O₃ granular films sputtered both at room temperature and at 473 K behave as superparamagnetic and the susceptibility of this film increases with increasing substrate temperature. Based on the feature of microstructure of FeCo (41vol.%)-Al₂O₃ granular films sputtered at both room temperature and 823 K, the evolution sequence of two-stage phase separation is suggested. In addition, the effect of the microstructure on tunnelling magnetoresistance has been discussed.     

Growth of textured LiNbO3 thin film on Si (111) substrate by pulsed laser deposition

Highly c-axis oriented LiNbO₃ thin films have been deposited on Si (111) substrates by pulsed laser deposition. A stoichiometric sintered LiNbO₃ is used as the target. The c-axis orientation and stoichiometry of LiNbO₃ films are strongly influenced by substrate temperature and oxygen pressure. The substrate temperature 600 °C and oxygen pressure 20–30 Pa are found to be optimized parameters for the growth of textured film. The results showed that the size and the density of droplets decreased with increasing substrate temperature, and droplets would disappear when substrate temperature is increased above 600 °C. The surface microstructures of LiNbO₃ films under optimized conditions are fine, uniform and dense. The AFM images ensured that the as-grown films are good enough to be integrated with the semiconductor devices.     

NiFe2O4–Ni3S2 nanorod array/Ni foam composite catalyst indirectly controlled by Fe3+ immersion for an efficient oxygen evolution reaction

A NiFe alloy was designed on nickel foam (NF) as a precursor using cathodic electrodeposition. NiFe₂O₄–Ni₃S₂ nanorods (NRs) composite catalysts were prepared by Fe³⁺ impregnation and further hydrothermal sulfuration methods. NiFe₂O₄–Ni₃S₂ nanosheets (NSs) were also prepared by direct hydrothermal sulfuration of the NiFe alloy for comparison. Compared to the dense NS structure of the NiFe₂O₄–Ni₃S₂ NSs/NF, the NiFe₂O₄–Ni₃S₂ NRs/NF showed better oxygen evolution performance due to its unique weed-like NR array structure composed of additional oxygen evolution reaction (OER) active sites, with a strong electron interaction for Ni and Fe and the active sulfide synergistic effect with oxides. Therefore, Driving a current density of 10 mA cm^?2 only requires an overpotential of 189 mV and the catalyst could provide 100 mA cm^?2 continuously and be constant for more than 80 h in 1.0 M KOH. This experiment indicated that Fe³⁺ immersion had an indirect regulating effect on the morphological growth of the catalyst, which provided a novel concept for designing better OER catalysts.     

A two-dimensional metal-organic framework composed of paddle-wheel cobalt clusters with permanent porosity

A cobalt(II)-organic framework, [Co₂(TPEC)(DMA)₂]·(DMA)₃ (1) (H₂TPEC = 1,1,2,2-tetra(4-(4-carboxyl-phenyl)benzenyl)ethene; DMA = N,N′’-dimethylacetamide), was synthesized and characterized by single crystal diffraction analysis. The structure shows a two-dimensional (2D) sheet composed of paddle-wheel Co₂(COO)₄ clusters linking TPEC ligands. The permanent porosity was established for the activated phase and gas sorption isotherms acquired.     

基于机电一体化系统设计理论的机电液综合实验台开发

为解决现有实验台实验项目综合性不强等问题,满足现代化实验教学及科研的要求,基于机电一体化系统设计理论,在现有工业滴丸机基本机械框架基础上,提出并研制机电液一体化综合实验台。采用机械设计理论对整体框架进行设计,选用精确控制液压阀组成液压控制模块。     

Improved cuckoo search algorithm for hybrid flow shop scheduling problems to minimize makespan

The multistage hybrid flow shop (HFS) scheduling problems are considered in this paper. Hybrid flowshop scheduling problems were proved to be NP-hard. A recently developed cuckoo search (CS) metaheuristic algorithm is presented in this paper to minimize the makespan for the HFS scheduling problems. A constructive heuristic called NEH heuristic is incorporated with the initial solutions to obtain the optimal or near optimal solutions rapidly in the improved cuckoo search (ICS) algorithm. The proposed algorithm is validated with the data from a leading furniture manufacturing company. Computational results show that the ICS algorithm outperforms many other metaheuristics.     

To use or not to use? Social media in higher education in developing countries

This research is a response to the universal use of social media by students for academic-related purposes. It bridges a gap in knowledge in relation to the value and use of social media as effective teaching and learning tool in higher education in developing countries. A pre-tested questionnaire survey was self-administered to faculty members in the eight public Egyptian higher institutions offering tourism and hotel management programs. The results showed that social media have a great value for academic-related purposes, particularly as teaching and learning tool; however, the actual use by faculty was at a minimal level. In-depth interviews were conducted to identify the perils, barriers and concerns for the minimal use. Several barriers were identified with some specific to developing countries' context. Nonetheless, there was consensus by faculty that if these barriers were overcome, social media could be developed as an innovative and effective tool for teaching and learning. Implications for researchers and policy makers are discussed.     

Recent progress in high efficiency polymer solar cells by rational design and energy level tuning of low bandgap copolymers with various electron-withdrawing units

AbstractThis review collects recent five-year publications on low bandgap semiconducting polymers, which are composed of electron donor (D) and electron acceptor (A) units, exhibiting the power conversion efficiency (PCE) higher than 6%. When the photovoltaic performances of different types of D−A semiconducting copolymers are compared after the copolymers are classified into several categories according to the type of A-units, it is realized that diketopyrrolopyrrole (DPP)-based copolymers exhibit high J_SCs owing to low bandgaps and low V_OCs due to high-lying HOMO levels, while thienopyrroledione (TPD)-based copolymers exhibit high V_OCs due to their deep HOMO levels and low J_SCs because of wide bandgaps. Benzothiadiazole- and thienothiophene-based copolymers show intermediate values of V_OC and J_SC between DPP- and TPD-based ones. For further enhancement of photovoltaic performance, DPP-based copolymers may be designed to have deeper HOMO level with the minimum widening of bandgap while TPD-based polymers may be designed to have lower bandgap with the minimum rise of HOMO level. Hence, the energy level tuning must be considered so as to minimize the adverse effect.     

Research on clothing design based on 5G network and FPGA

Mobile phone technology is thought to have developed in huge demand in the next few years, it exists. 5 G and related techniques, better data transmission rates, improved productivity, low latency, and high-quality services such as a number of major goals, can be solved. To analyze the cultural characteristics of the performance, explaining the characteristics of thinking of positioning principles and modern clothing brand. From the perspective of expressionism and print advertising, literary support, case studies and image analysis, Self-Organizing Map (SOM) network training analysis, summarizing the relationship with the method of painting, the influence of expressionism Conceptual picture summaries, modes, compositions and colors are represented in recent international clothing brand print advertisements. Evaluated and suitable for communication methods such as discontinuous carrier aggregation, centralized processing, and 5 G waveform coexistence Field Programmable Gate Array (FPGA) baseband processing architecture. Cost-effectiveness, and support for5G waveform candidates. Design details, key technologies, and how to actually implement a smart clothing system. A typical application for smart clothing. It still highlights some design challenges and open issues that need to be addressed to make smart clothes for a wide range of applications.     

0D/3D ZnIn2S4/Ag6Si2O7 nanocomposite with direct Z-scheme heterojunction for efficient photocatalytic H2 evolution under visible light

Constructing heterojunction structure is a feasible way to realize an efficient and durable photocatalysts. Herein, a novel Z-scheme zero/three dimensional (0D/3D) ZnIn₂S₄/Ag₆Si₂O₇ (ZIS/ASO) composite was rationally designed, synthesized and analyzed. ZIS/ASO composite possesses a layer structure for increasing light response, a special 0D/3D structure for reducing the photo-induce carriers migration path, and numerous active sites for absorbing H₂O and producing H₂. This composite retains the high oxidation and reduction ability by facilitating separation and migration as well as limiting recombination of photo-induced carriers via the intimate interface between ZIS and ASO. Undoubtedly, the synthesized ZIS/ASO photocatalyst achieved a high photocatalytic H₂ activity, and the optimum sample shows a satisfactory H₂ evolution rate of 590.56 μmol g⁻¹ h⁻¹, distinctly better than that of pure ZIS. More importantly, this composite exhibits high stability and recyclability and is expected to be applied in practical application. Based on the H₂ evolution experimental results and electrochemical tests, the Z-scheme heterostructure construction of the composite was confirmed. This work expects to inspire a unique protocol for synthesizing Z-scheme photocatalysts for water splitting under visible light irradiation.