In order to solve the difficult problem in analyzing the shaping law of numerical control electrochemical machining (NC-ECM) with ball-end cathode, the process simulation based on the finite element method (FEM) is used in this paper. First, the two-dimensional analysis model of the electric field in NC-ECM with ball-end tool-electrode built by use of ANSYS software was solved, and the current density distribution and the machined surface shape on the workpiece were obtained. Then, the experiments based on the simulation parameters were carried out, and the cutting depth values were measured. Finally, the accuracy of the simulation was verified by the comparison between the calculated values and the actual values. The experiments showed that the simulation method meets the accuracy of the engineering calculations in NC-ECM.
An increase in the removal selectivity between silicon oxide and silicon nitride was attempted by adding organic additives to a ceria slurry for the application of shallow trench isolation (STI) chemical mechanical planarization (CMP). The protection behavior of poly(acrylic acid) (PAA) and the acceleration behavior of RE-610 in a ceria slurry were studied. PAA served as a protector of the silicon nitride due to the change in zeta potential. RE-610 worked as a hydration accelerator of the silicon oxide. When the two additives were added to the ceria slurry, the removal selectivity increased to 31:1. Moreover, PAA improved the stability of the ceria slurry.
In order to improve the performances of micro tillage machine blades, Ni-Co-P/BN(h) nanocomposite coatings were prepared on the surface of 65Mn by jet electrodeposition. The surface morphology, friction wear, and micro-hardness of the Ni-Co-P/BN(h) nanocomposite coatings were characterized by OLS4100, XRD, friction wear testing machine and Vickers micro-hardness tester, respectively. The corrosion resistance of coatings in the solution of 50 g/L NaCl was studied. The results showed that coatings surface could get better performances when the voltage is 16 V, bath temperature is 70 °C, poles gap is 1.6 mm and BN(h) nanoparticles concentration is 8 g/L. The microstructure of Ni-Co-P/BN(h) nanocomposite coatings is uniform and dense. The surface friction coefficient of the coatings is obviously reduced, and the corrosion resistance is improved. After the heat treatment, the hardness of coatings is higher than the 65Mn matrix.
Global climate change has increased the frequency of extreme climate events, and their effects on the nutritional quality, especially on amino acids in rice, have not been quantified. The data from a 3-year low temperature stress (LTS) experiment including two rice varieties (Huaidao 5 and Nanjing 46), seven minimum/maximum temperature levels (one optimal 21/27°C and six LTS levels from 17/23 to 6/12°C), and three LTS durations (3, 6, and 9 days) after flowering, revealed significant interactive effects of LTS at different stages, durations, and temperature levels on the content and accumulation of amino acids. LTS increased rice total amino acid content, while decreasing its accumulation, with higher sensitivities to LTS at the flowering stage than at the grain filling stage. In most treatments, the lysine (the first limiting amino acid) and phenylalanine content were increased under LTS at early and peak flowering stages but decreased at the grain filling stage in both varieties, and only leucine content was increased at all three stages after flowering, while the content of other essential amino acids differed among the two varieties. With an increase of 1°C·d per day in the accumulated cold degree days, the relative content of the essential amino acids was increased by 0.01–0.41%, depending on the rice variety and growth stage. Our results suggest that LTS can improve nutritional quality of amino acids of rice grains in terms of amino acids content, especially at flowering stage. These results provide critical insights for assessing the potential impact of extreme climates on the nutrient quality of rice under future climate change.
Microplastic pollution has become a primary global concern in the 21st century. Recyclable magnetic particles with micro-nanostructures are considered an efficient and economical way to remove microplastics from water. In this study, superhydrophobic magnetic cobalt ferrite particles were prepared by using a simple coprecipitation method combined with surface functionalization. The micromorphology, chemical composition, hysteresis loop, and surface contact angle of the functionalized cobalt ferrite were characterized. The separation efficiency and absorption capacity of cobalt ferrite particles in water-oil separation and microplastic removal were investigated. The results showed that the saturation magnetic field intensity of cobalt ferrite was 65.52 emu/g, the residual magnetization intensity (Mr) was 18.79 emu/g, and the low coercivity was 799.83 Oe. Cobalt ferrites had stable superhydrophobicity in the pH range of 1-13. The separation efficiency of cobalt ferrite powder for four oil-water mixture separations was higher than 94.2%. The separation efficiency was as high as 99.6% in the separation of the hexane and water mixtures. Due to the synergistic effect of the hydrophobic effect and van der Waals force, the functionalized magnetic cobalt ferrite had a high and stable microplastic removal efficiency and capture capacity. The removal efficiency of microplastics was close to 100%, and the capture capacity was 2.56 g/g. After ten microplastic removal cycles, the removal efficiency reached more than 98%, and the surface contact angle was still greater than 150°.
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