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The nano-Ni-Al2O3/A356 nanocomposites prepared with nickel-plating, stir casting, and equal channel angle semi-solid extrusion (ECASE). The microstructure, tensile property, and fracture morphology of the fabricated nanocomposites have been investigated. The microstructure observation showed the nickel-plating could stimulate nucleation and break nanoparticle aggregation, resulting the matrix grains in a smaller size (63 μm) and the nanoparticles more uniform located on the grain boundary. The ECASE could further refine the grains size (23 μm) and improve the nanoparticle dispersion. Although 5 passes refine the grains to 16 μm, it would cause the particles to re-agglomerate, due to the nanoparticles exist in the semi-solid liquid phase for a long time. The fabricated nanocomposites exhibited an enhancement in both strength and ductility, about 1.2–2.5 times higher than those of the corresponding aluminum matrix composites. Due to the Orowan strengthening and fine grain strengthening, i.e., increased the number of grain boundaries and improved the resistance of particles to cooperative grain deformation. Meanwhile, the ECASE eliminated the intergranular defects and improved the grain boundary bonding. The enhanced mechanical properties of the nanocomposites were attributed to the grain boundary control increased by the nickel-plating and ECASE. The grain boundary control, such as increasing the grain boundary number, improving the particle-matrix adhesion and particle dispersion, can be applied to the development of high mechanical properties aluminum matrix composites.

Soil water content is a critical environmental parameter in research and practice, though various technological and contextual constraints limit its estimation in arid areas with vegetation cover. This study combined the multitemporal remote sensing data of Sentinel-1 and Landsat 8 to conduct an inversion study on surface soil water content under low vegetation cover in Nagqu, central Tibetan Plateau. Four vegetation indices (NDVI, ARVI, EVI, and RVI) were extracted from optical remote sensing data. A water cloud model was used to eliminate the influence of the vegetation layer on the backscattering coefficient associated with vegetation cover, and a predictive model suitable for the Nagqu area was constructed. The water cloud model effectively incorporated a vegetation index instead of vegetation water content. We found that VV polarization was more suitable for soil water content inversion than VH polarization. Among the four vegetation indices, the soil water content inversion model constructed with RVI under VV polarization had the best fit (R2 = 0.8212; RMSE = 6.30). The second-best fit was observed for vegetation water content-NDVI (R2 = 0.8201). The soil water content inversion models all had an R2 > 0.6, regardless of the vegetation index used, though the RVI had the best fitting effect, indicating that this vegetation index is highly applicable in the water cloud model, as a substitute for vegetation water content, and is expected to perform well in similar study sites.

AlCa75 with equal Ca content was used to replace pure Ca for the preparation of AlSi12 foam in a stable pore structure after foaming for 20 min. The stability mechanism was studied based on the comparison between the macroscopic pore structure evolution and the second phase composition of AlCa75 and pure Ca aluminum foam. It was found that the porosity and average pore size of the AlSi12 foam with AlCa75 were stable without any abnormal large pores, and the foaming stage was prominent. The stability of AlSi12 foam with pure Ca is inferior. After 20 min of foaming, the foam bursts in the center. Combined with the microscopic characteristic analysis, it could see that the second phase produced by AlCa75 is mainly Al2Si2Ca, which can be uniformly dispersed in the matrix. The addition of pure Ca reduces the amount of the second phase and the main phase Al4Ca is easy to agglomerate. The stability mechanism shows that the Al2Si2Ca second phase, formed by AlCa75, demonstrates a better stabilizing effect in different foaming stages. Due to the premature agglomeration caused by Al4Ca and the low content of the second phase, the AlSi12 foam with pure Ca is challenging to long-term stability.

Abstract

ZL104 alloy foam and ZL104 alloy/aluminum fiber composite foams with a porosity of 71–90% were prepared by an infiltration casting method. The pore structure and the sound absorption properties of these two kinds of foams were studied. The results show that fibers partially embedded in the porous pore walls and partially extending out of the pore in the composite foams. The sound absorption coefficient of the foams has a sound absorption peak and a sound absorption trough with increasing frequency. The fiber composite foam possesses better sound absorption properties compared with the alloy foam. As porosity, fiber diameter, and fiber content increases, the average sound absorption coefficient of the composite foam first increases and then decreases. The average sound absorption coefficient (0.88) of the composite foam with a fiber content of 5 vol%, a fiber diameter of 0.1 mm, and a porosity of 82% increased 10% compared with that of the alloy foam. The surface roughness and specific surface area of the foam increase after fiber compounding, and the sound wave drives the fibers to vibrate to enlarge the consumption of sound energy.

AbstractInSAR technology provides a powerful tool for detecting large-scale surface deformation. In particular, the newly developed DS-InSAR method fused PS points has obvious advantages in monitoring bare land and vegetation covered areas, but at present, there is a lack of effectiveness evaluation of this method. Therefore, this paper takes Hongta District of Yuxi City as an example. The 29 scenes sentinel-1A data from January 2019 to December 2019 were processed and analyzed using the DS-InSAR method fused PS points. The research results show that the position and deformation trend of the inversion results of the three methods are highly consistent, the correlation between DS-InSAR method fused PS points and PS- InSAR and SBAS-InSAR methods is 0.9473 and 0.8583, respectively. But the spatial density of the measurement points (MPs) obtained by the DS-InSAR method of PS points is 11 times and 4 times that of the PS-InSAR method and SBAS-InSAR method respectively. It clearly shows that DS-InSAR method fused PS points has greater advantages than PS-InSAR and SBAS-InSAR methods in deformation mapping displacement, because the MPs density is higher. It is conducive to the detailed analysis of the spatio-temporal characteristics and deformation mechanism of deformation.

The research on finding a suitable electrode material with high capacitance, stability, and rate performance is highly desirable for the advanced energy storage domain is a hot topic for a decade. Currently, metal selenides (MSs) are involved in considerable attention is owed to their unique physical and chemical properties. Herein, selenide/selenide composite based on NiSe2, SnSe, and their nanocomposite of NiSe2/SnSe (denoted as SN-1 and SN-2) was prepared via wet-assisted chemical method for the electrochemical energy domain. The comparative review showed that higher charge storage response was noticed for the SnSe electrode than the NiSe2electrode due to its high conductivity, which is confirmed by the impedance plot. All electrodes pseudocapacitive charge storage response due to well-defined voltage plateaus and noticeable redox peaks in their charge/discharge, and the CV diagram. The SN-2||AC||KOH hybrid supercapacitor expands the voltage to 1.8 V, which supplies high energy (65.47 Wh kg−1) and power delivery (4500 W kg−1) with robust longevity of 94.4 % after 8000 galvanostatic charge/discharge platforms at 15 A/g. This study manifests that the construction of binary, ternary, and even quarterly composites can be utilized as effective electrodes for the future electronic market.

This work proposed a facile synthesis of NiSe2-CoSe nanocomposite via an economical wet-chemical assisted method for the electrochemical energy storage domain, specifically for supercapacitor applications. The morphological, structural, and surface chemistry characterization guarantee the appropriate formation of the micro flower and nanoparticles-like morphology with high purity, crystallinity, and the existence of Ni, Co, and Se elements on the surface of the samples was verified by EDX examination. The comparative electrochemical properties reveal that the NiSe2-CoSe nanocomposite electrode yields an optimized performance than NiSe2and CoSe electrodes in an aqueous solution with improved capacitance and charge transport kinetics. The synergistic effect between metal selenide nanomaterials could effectively realize the excellent charge storage properties of the NiSe2-CoSe nanocomposite. Strikingly, a voltage runs to 1.7 V by assembling a hybrid supercapacitor of NiSe2-CoSe||AC||KOH in the two-electrode mode for utilization towards the practical aspect. More specifically, high stability of 89.6 % was sustained at 20 A/g for 20,000 cyclings with durable performance. Additionally, a high power of 8460 W/kg was achieved when the energy density progressively reached 54.9 Wh/kg. The use of chalcogenide is now the top priority for electrochemical energy conversion and storage, thanks to these encouraging results.

The rational design and impressive performance of the desired electrode material are one of the top priorities in the field of the supercapacitor era. Chalcogenides are functional materials that attracted tremendous research due to their great electrochemical activity, non-toxicity, high theoretical capacities, low cost, high environmental safety, and tunable electronic configurations. Combining two different materials (compositing strategy) is a popular route to develop novel, robust, and highly efficient electrodes for high capacity, energy, and power delivery with good durability. Herein, for the first time, a high-performance hybrid supercapacitor is developed based on NiSe2, and CdSe and their composites, e.g., NiSe2/CdSe (denoted as CN-1, CN-2, and CN-3) via hydrothermal via ex-situ wet-chemical method. By changing the stoichiometry of the host compounds (e.g., NiSe2, CdSe), various nanocomposites take birth, such as; CN-1, CN-2, and CN-3. Notably, their capacitive performance was measured and compared in an aqueous alkaline media in KOH with three milli molar concentration. Subsequently, the CN-2 electrode displayed a good electrochemical energy storage performance of 358C/g capacity and lower overall resistance, which promotes the fast diffusion of electrolyte kinetics; hence, optimized electrochemical properties prove its importance for the fabrication of full cell development. More strikingly, the CN-2//AC hybrid supercapacitor revealed a high capacitance of 90 F/g, 40.5 Wh/kg energy density, and a maximum power of 7161.2 W/kg coupled with a high stability of 87.6 % (20 A/g) when repeatedly tested for long-term 15,000 cycling. The proposed method portrays a cost-effective and appealing runner for high-energy hybrid supercapacitors in future energy storage applications.

Nanoscale low-dimensional chiral architectures are increasingly receiving scientific interest, because of their potential applications in many fields such as chiral recognition, separation and transformation. Using 6,12-dibromochrysene (DBCh), we successfully constructed and characterized the large-area two-dimensional chiral networks on Au(111) and one-dimensional metal-liganded chiral chains on Cu(111) respectively. The reasons and processes of chiral transformation of chiral networks on Au(111) were analyzed. We used scanning tunneling spectroscopy (STS) to analyze the electronic state information of this chiral structure. This work combines scanning tunneling microscopy (STM) with non-contact atomic force microscopy (nc-AFM) techniques to achieve ultra-high-resolution characterization of chiral structures on low-dimensional surfaces, which may be applied to the bond analysis of functional nanofilms. Density functional theory (DFT) was used to simulate the adsorption behavior of the molecular and energy analysis in order to verify the experimental results.