There are a large number of fouling organisms in the ocean, which easily attach to the surface of ships, oil platforms and breeding facilities, corrode the surface of equipment, accelerate the aging of equipment, affect the stability and safety of marine facilities and cause serious economic losses. Antifouling coating is an effective method to prevent marine biological fouling. Traditional organic tin and copper oxide coatings are toxic and will contaminate seawater and destroy marine ecology and have been banned or restricted. Environmentally friendly antifouling coatings have become a research hotspot. Among them, the use of natural biological products with antifouling activity as antifouling agents is an important research direction. In addition, some fouling release coatings without antifoulants, biomimetic coatings, photocatalytic coatings and other novel antifouling coatings have also developed rapidly. On the basis of revealing the mechanism of marine biofouling, this paper reviews the latest research strategies to develop environmentally friendly marine antifouling coatings. The composition, antifouling characteristics, antifouling mechanism and effects of various coatings were analyzed emphatically. Finally, the development prospects and future development directions of marine antifouling coatings are forecasted.

Polymer additives and surfactants as drag reduction agents have been widely used in the field of fluid drag reduction. Polymer additives can reduce drag effectively with only a small amount, but they degrade easily. Surfactants have an anti-degradation ability. This paper categorizes the mechanism of drag reducing agents and the influencing factors of drag reduction characteristics. The factors affecting the degradation of polymer additives and the anti-degradation properties of surfactants are discussed. A mixture of polymer additive and surfactant has the characteristics of high shear resistance, a lower critical micelle concentration (CMC), and a good drag reduction effect at higher Reynolds numbers. Therefore, this paper focuses more on a drag reducing agent mixed with a polymer and a surfactant, including the mechanism model, drag reduction characteristics, and anti-degradation ability.

Conductive hydrogels have great potential in the field of electrophysiological signal acquisition because of their outstanding properties.

As a new type of flexible smart material, ionic polymer-metal composite (IPMC) has the advantages of being lightweight and having fast responses, good flexibility, and large deformation ranges. However, IPMC has the disadvantages of a small driving force and short lifespan. Based on this, this paper firstly analyzes the driving mechanism of IPMC. Then, it focuses on the current preparation technology of IPMC from the aspects of electroless plating and mechanical plating. The advantages and disadvantages of various preparation methods are analyzed. Due to the special driving mechanism of IPMC, there is a problem of short non-aqueous working time. Therefore, the modification research of IPMC is reviewed from the aspects of the basement membrane, working medium, and electrode materials. Finally, the current challenges and future development prospects of IPMC are discussed.

Water management has been an unavoidable problem for proton exchange membrane fuel cells (PEMFCs), and effective water management measures can improve the performance and extend the lifespan of the PEMFC.

The vortex structure is a typically coherent structure. The influence of hydrofoil jets with different chordal positions on the vortex structure in the hydrofoil flow field is investigated to improve the suppression mechanism of cavitation by jet hydrofoils. The investigation is based on a vortex identification method and the chordal position with the best suppression effect on the large-scale vortex on the hydrofoil surface is explored. In addition, the dynamics of the vortex structure in different cavitation states are analyzed by means of vortex transport equations based on the optimal chordwise position. The results show that the U-shaped vortex is the main morphology of the hydrofoil surface bubble shedding; the results show that the U-shaped vortex is the main form of cavitation shedding on the hydrofoil surface; compared with the original hydrofoil and other jet positions, the shedding of large-scale vortex structure can be suppressed better when the jet is located at 0.6c; the dominant vorticity transport terms are different in various cavitation stages. In the primary cavitation stage, the vorticity dilatation term is dominant. In contrast, during the development, maturation, and shedding phases, the vortex stretching term dominates, reducing the pressure gradient in the hydrofoil flow field and suppressing the strength of the return jet.