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All-inorganic perovskite cesium lead bromide (CsPbBr3) quantum dots (QDs) have been used as charge storage centers in floating-gate transistors. In this work, CsPbBr3 QDs are integrated into thin film transistors to create transistor-based memory. Unlike the floating-gate transistors previously reported, the CsPbBr3 QDs are placed between the dielectric and semiconductor layer, leading to direct contact with the semiconductor layer. Characterization of the device performance reveals that the CsPbBr3 QDs exhibit a strong tendency to store holes instead of electrons. Analysis unravels that this property possibly comes from the junction formed between the CsPbBr3 QDs and the transistor’s semiconductor layer, which can facilitate hole injection from the semiconductor layer to the QDs under a negative gate bias, as well as the storage of the injected holes in the QDs. Devices using an organic semiconductor (P3HT) or two-dimensional material (graphene) consistently verify this speculation. Benefiting from the hole storage ability of the CsPbBr3 QDs, these devices show a benign non-volatile memory feature. As transistor-based memories, these devices can be programmed by electricity and erased by electricity or light illumination, rendering them as capable of optoelectronic memory application. This work offers an alternative approach for novel transistor-based optoelectronic memory.

There are more than 18,000 butterflies in the world. Butterflies are essential cultural insects and have great significance in the field of insect research. However, due to its high similarity, various type, and the characteristics of the distinction is not apparent, the recognition and classification of butterflies at this stage has the problems of low accuracy and slow recognition speed, so it is of great significance to make research on the automatic identification of butterflies and improve the efficiency of automatic identification of butterflies. This paper uses the Faster R-CNN algorithm for butterfly recognition and describes the whole process from butterfly dataset selection, butterfly dataset processing, to butterfly classification. The experimental results show that the butterfly automatic recognition system based on the Faster R-CNN deep learning framework can realize automatic detection and species identification of butterfly photos in the ecological environment, and the average classification accuracy can reach 70.4%.

We present a thorough study of the nucleation and growth processes of the solution-based YBa2Cu3O7?Ba2YTaO6 (YBCO?BYTO) system, carried out with a view to controlling the characteristics of the BYTO phase to meet the requirements for specific power applications. Scanning transmission electron microscopy and x-ray diffraction have been used to characterize the BYTO nucleation and phase evolution during the YBCO?BYTO conversion. At high BYTO loads (>10?mol%), the nanoparticles tend to aggregate, resulting in much less efficiency for generating nanostrained areas in the YBCO matrix, and enhancement of the vortex pinning. Our experiments show that by modifying the nucleation kinetics and thermodynamics of the BYTO, the nucleation mode (homogeneous versus heterogeneous), the particle size and the particle orientation can be controlled. We demonstrate that YBCO?BYTO nanocomposites with high concentration of nanoparticles can be prepared in such a way as to obtain small and randomly oriented nanoparticles (i.e. high incoherent interface), generating highly strained nanoareas in the YBCO, with enhancement in the vortex pinning. We have also observed that the incoherent interface is not the only parameter controlling the nanostrain. The Cu?O intergrowth characteristics must also be a key factor for controlling the nanostrain in future tuning of YBCO vortex pinning.

We report on the spontaneous segregation of double perovskite Ba2YTaO6 (BYTO) nanoparticles within YBa2Cu3O7 (YBCO) films forming a nanocomposite with two ternary oxides by the low cost and scalable chemical solution trifluoroacetate approach. Phase orientation, nanostructural and pinning studies are carried out by 2D x-ray diffraction, advanced scanning transmission electron microscopy and transport measurements, respectively. In this complex oxide nanocomposite system (YBCO–BYTO) the majority of the nanoparticles segregated within the (00l)-oriented superconducting matrix are randomly oriented. The presence of randomly oriented nanoparticles plays a key role in the generation of localized highly strained areas within the YBCO matrix which are suggested to strongly affect the superconducting properties. The incorporation of 6–10% of BYTO resulted in a maximum pinning force, at 77 K, three times higher than that obtained for a pristine sample, while Tc was maintained at 89–90 K.

YBa2Cu3O7−δ (YBCO) films with Zr doping have been prepared successfully by the trifluoroacetate metal–organic deposition (TFA-MOD) method through dissolving Zr acetylacetonate in the precursor solution. Yttria-stabilized zirconia (YSZ) nanoparticles were detected in the doped YBCO films by x-ray diffraction (XRD) and scanning electron microscopy (SEM). From the analysis of XRD ω and scans, the doped films have better out-of-plane and in-plane textures than those of the un-doped YBCO film. Although the doped YBCO films have a lower critical transition temperature (Tc) than that of un-doped YBCO film, a very significant enhancement of critical current density (Jc) is displayed as compared to the un-doped film at high applied fields. A high Jc near 106 A cm−2 at 1 T and a Jc of 105 A cm−2 at 5 T were observed in 6% doped Zr film, which are 5 times and 25 times the Jc values of the un-doped film in the same applied fields, respectively, indicating an optimal defect density created by 6% Zr doping.

Mechanically strengthened, highly cube textured Ni?7?at.%W/Ni?12?at.%W multi-layer substrates developed for coated conductors have been prepared by the advanced spark plasma sintering technique. The key innovation for developing this weakly magnetic and reinforced substrate was to use a new powder metallurgy and sintering route to bond multi-layers of Ni7W/Ni12W/Ni7W together in order to get an initial ingot, followed by the optimized cold working and annealing. Particular efforts were made in view of the optimization of the design, pressing as well as the heat treatment processes of the starting ingots to obtain a chemically gradient composite bulk, thus ensuring the subsequent cold deformation. The produced composite substrates have a strong {100} texture on Ni7W outer layers. The percentage of the biaxially orientated grains within a misorientation angle of 10? is as high as 97.5%, while the length percentage of low-angle grain boundaries ranging from 2? to 10? in the composite substrate reaches 87.2%. Moreover, the yield strength ?0.2 of the tape approaches 333?MPa, and the saturation magnetization is substantially reduced by 81.6% at 77?K when compared to that of a commercial used Ni5W substrate.

Mechanically strengthened, highly cube textured Ni-7at.%W/Ni-12at.%W multi-layer substrates used for coated conductors have been prepared by advanced spark plasma sintering technique. The key innovation for developing this weakly magnetic and reinforced substrate was to use a new powder metallurgy and sintering route to bond multi-layers of Ni7W-Ni12W-Ni7W together in order to get an initial ingot, then followed by optimized cold working and annealing. Particular efforts were made in view of the optimization of the design, pressing as well as the heat treatment processes of the starting ingots in order to obtain a chemically gradient composite bulk, thus ensuring the subsequent cold deformation of the bulk. The produced composite substrates have a strong {100} texture on the top Ni7W outer layer determined by EBSD and X-ray. The percentage of the biaxially orientated grains within a misorientation angle of 10° is as high as 97.5%, while the length percentage of low angle GBs ranging from 2° to 10° in the composite substrate reaches 87.2%. Moreover, the yield strength σ0.2 of the tape approaches 333 MPa, and the saturation magnetization is substantially reduced by 81.6% at 77K when compared to that of a commercial used Ni5W substrate.

We report on the development of mechanically strengthened, highly textured Ni–5 at.%W/Ni–12 at.%W composite materials prepared by a powder metallurgical approach as promising weakly magnetic substrates for coated superconductors. The key configuration of this composite substrate consists of a thin, sharp cubic textured Ni–5 at.%W layer on a Ni–12 at.%W alloy core, thus providing a mechanical reinforcement while decreasing the saturation magnetization of the whole substrate. The composite substrates have a sharp cubic texture at the top Ni–5 at.%W outer layer and their yield strength reaches 272 MPa, exceeding that of the commercially used Ni5W substrates by a factor of 1.6. The saturation magnetization of the composite substrate Ni5W/Ni12W/Ni5W is substantially reduced when compared to that of pure Ni and Ni–5 at.%W substrates, respectively.