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This article presents an experiment of rocket-triggered lightning to 10 kV power distribution lines and the characteristics of lightning current at Guangzhou Field Experiment Site for Lightning Research and Testing during 2018–2019. The return strokes (RSs) current of the triggered-lightning flashes in this study exhibits a shorter half-peak width and similar risetime and peak current compared with those of subsequent strokes current from natural lightning. The peak current of RSs shows strong power function correlations with charge transfer within 1 ms and action integral within 1 ms of RSs, with R2 of 0.80 and 0.92, respectively. Besides, the peak current of RSs is proportional to the average rate rise of RSs (dI/dt). We recommend the double HEIDLER function to simulate the RS current and provide accurate raw data for the study of lightning protection.

The impulse grounding performance of distribution lines tower is the key factor to lightning protection. Few field high-current impulse test researches are conducted on distribution line tower. In this paper, we used a mobile high-current impulse generator to conduct test on a 10 kV distribution line tower. The peak value of the current injection is 6 kA to 16 kA. The impulse impedance and the surface potential distribution are measured and analyzed. Based on the CDEGS software, an equivalent modeling of the experiment was carried out. The influence of soil ionization was taken into account by the method of changing the conductor radius through two rounds of calculation. The simulation and measured results were basically consistent. Experiments have shown that the soil ionization effect has an important impact on lightning performance of distribution line tower. The graphite earthing modules (GEMs) and pulling wires can significantly reduce the impulse impedance of the tower. The potential rise of the earth surface at a distance of 30 m from the tower can reach 1 kV at peak, under an injection of 7.15 kA.

Heterogeneous catalysts have made outstanding advancements in pollutants elimination as well as energy and materials production over the past decades. Single-atom alloys (SAAs) are novel environmental catalysts prepared by dispersing single metal atoms on other metals. Integrating the advantages of single atom and alloys, SAAs can maximize atom utilization, reduce the use of noble metals and enhance catalytic performances. The synergistic, electronic and geometric effects of SAAs are effective to modulate the activation energy and adsorption strength, consequently breaking linear scaling relationship as well as offering an excellent catalytic activity and selectivity. Moreover, SAAs possess clear atomic structure, active sites and reaction mechanisms, providing an opportunity to tailor catalytic properties and develop effective environmental catalysts. In this review, we provide the recent progress on synthetic strategies, catalytic properties and catalyst design of SAAs. Furthermore, the applications of SAAs in environmental catalysis are introduced towards catalytic conversion and elimination of different air pollutants in many important reactions including (electrochemical) oxidation of volatile organic compounds (VOCs), dehydrogenation of VOCs, CO2 conversion, NOx reduction, CO oxidation, SO3 decomposition, etc. Finally, challenges and opportunities of SAAs in a broad environmental field are proposed.

Macrophages are involved in the early inflammation during tissue repair and play a distinctive role in maintaining the stability of the tissue microenvironment. However, it is still very difficult to accurately regulate the phenotypic transformation of macrophages during bone repair. The current study innovatively used 4-octyl itaconate (OI), a cell-permeable derivative of an endogenous anti-inflammatory metabolite itaconate (IA), to regulate the polarization of macrophages and enhance the quality of bone repair. Chitosan (CS) was selected as a bridge in coating OI on demineralized bone matrix (DBM) scaffold to generate three-dimensional (3D) bone integration scaffold (OI/CS/DBM scaffold). Whether this metabolite derivative can exert the same anti-inflammatory effect as the metabolite itself was validated both in vitro and in vivo. In vitro cellular results showed that both OI and OI/CS/DBM scaffold could promote the formation of anti-inflammatory phenotype of macrophages, and the osteogenic differentiation of mesenchymal stem cells (MSCs) was indirectly enhanced by macrophage supernatant medium. In vivo studies of a rat skull defect model further proved that the OI/CS/DBM scaffold could improve the bone integration. In this study, the OI/CS/DBM scaffold was successfully fabricated as a vehicle for delivering OI, which was proved to have the ability to promote bone integration by regulating early inflammation. The present results may provide a novel method to improve bone repair with metabolites derivative to regulate the inflammation.