Coatings

High voltage direct current (HVDC) gas-insulated equipment (GIE) has become a critical component in long-distance power transmission projects, owing to its advantages such as compact structure and high reliability. However, the gas–solid interface insulation of DC GIE under long-term operation faces charge accumulation phenomenon, which will distort the electric field distribution and cause insulation flashover. Due to the lack of technical guidelines for the insulation design of DC gas-insulated equipment, the method of insulation design usually adopts increasing the insulation structure size to ensure sufficient creepage along the surface, which greatly increases the dimensions and manufacturing costs of the final equipment, and fails to fully leverage the unique advantages of GIE in compactness and lightness. Therefore, it is of importance to clarify the mechanism of charge accumulation on the surface of insulators under HVDC, and to propose an insulation design method that can effectively inhibit the charge accumulation and adjust the electric field distribution at the gas–solid interface, which holds practical significance for the safe application of large-scale DC GIE projects. In view of this, this paper firstly summarizes the characteristics of surface charge accumulation at gas–solid interface, and then reviews the existing research progress from two perspectives: surface charge suppression of insulation structure and gas–solid interface electric field regulation, providing theoretical and technical support for optimizing the design of GIE insulation structure, formulating scientific operation and maintenance measures.

Silver nanoparticles (AgNPs) have been widely employed across various industrial, medical, and consumer applications due to their unique biocidal properties, raising concerns about their potential impact on biota such as planktonic microinvertebrates, which, in turn, necessitates the rapid development of in vivo nanotoxicological bioassays. Here, we combined physicochemical particle characterization with organismal responses to assess the in vivo nanotoxicity of chemically synthesized AgNPs in the marine rotifer Brachionus plicatilis (Ploimida, Brachionidae). Particles were fully characterized by dynamic light scattering (hydrodynamic diameter and polydispersity), zeta potential, transmission electron microscopy, and UV–Vis spectroscopy in both stock and exposure media. Rotifers were exposed to low AgNP concentrations: 0 (control), 2, and 20 µg/L. After a 24 h exposure, in vivo metabolic activity was quantified via resazurin reduction. Reactive oxygen species (ROS) were measured using the fluorescent probe H₂DCF-DA (excitation 485 nm, emission 530 nm), quantified by fluorimeter and fluorescence microscopy. Results showed that AgNP exposure decreased ROS levels at both tested concentrations, a finding that can be linked to reduced aerobic metabolic activity in the rotifers. These findings demonstrate that B. plicatilis provides a rapid and sensitive in vivo toxicity assessment that integrates metabolic and ROS endpoints for nano-ecotoxicity evaluations.

Structural failure of the lead-carbon battery casing under external loads poses a serious threat to the safety of its energy storage function. To overcome the limitations of traditional protective casings regarding specific energy absorption (SEA) and crush force efficiency (CFE), this study proposes a novel thin-walled protective structure utilizing graded aperture honeycomb sandwich panels fabricated via additive manufacturing (AM). Finite element (FE) models were established using HyperMesh and validated against experimental data. Subsequently, the impact resistance and energy absorption characteristics of four distinct cellular topologies were systematically investigated under varying pore-size gradients, impact directions, and velocities. Experimental and numerical simulation results indicate that, among the investigated configurations, the triangular honeycomb structure exhibits superior impact resistance and energy absorption capability under both axial and lateral loading conditions. Furthermore, the synergistic enhancement mechanism based on topological configuration and gradient design effectively optimizes the progressive crushing mode, thereby reducing the initial peak crushing force transmitted to the battery and resulting in a pronounced advantage in impact performance. This research provides a novel design approach for optimizing next-generation high-performance, lightweight protection systems for energy storage devices.