Auxetic metamaterials and structures have excellent mechanical properties such as shear resistance, impact resistance, fracture resistance, energy absorption and vibration isolation, permeability variability, synclastic curvature in bending, <i>etc</i>. Auxetic metamaterials have broad application prospects in the fields of aerospace, navigation, mechanical automation, biomedicine, national defense and military and textile industry. Based on the deformation mechanism of auxetic metamaterials and structure, the physical models of re-entrant mechanism, rotating rigid mechanism, chiral/antichiral mechanism, fibril/nodule mechanism, miura-folded mechanism, buckling-induced mechanism, helical auxetic yarn structure were reviewed. These models can be widely applied in various engineering applications such as light laminated plates, fluid transportation and yarn to improve their properties. Finally, prospects to the upcoming challenges and progress trends of auxetic metamaterials and structures are made.It is pointed out that the application of negative Poisson’s ratio effect can help compensate the change of volume and area under the deformation of uniaxial loading. Then the shock resistance of turbine blade, antenna and car suction box can be improved. As a result, this review can provide benefits for the development of auxetic metamaterials.

Ferrosilicon alloy is widely used as alloying agent and deoxidizer in the steelmaking process, which containing the metallic impurities of Al, Ca, and Ti would directly affect the cleanliness of the molten steel. Therefore, metallic impurities from the ferrosilicon alloy removed by the top blowing Ar-O₂ gas was carried out. The morphology, composition, and area fraction of impurity phases of metallic impurities in the ferrosilicon alloy were compared before and after Ar-O₂ gas blowing treatment by automatic scanning electron microscopy, and contents of metallic impurities were measured by inductively coupled plasma atomic emission spectrometry (ICP-AES). The results show that a large amount of metallic impurity phases precipitate in the ferrosilicon alloy raw material, which mainly contain Al, Ca, and Ti impurities, and their contents are 1.11% (mass fraction, the same below), 0.31% and 0.11%, respectively. After blowing Ar-O₂ gas for 5 minutes, contents of Al and Ca are dropped sharply to 0.66% and 0.13%, respectively. After blowing Ar-O₂ gas from 45 minutes, the removal rate of impurity elements is slowed down and the refining reaction tends to reach equilibrium. After 120 minutes of blowing Ar-O₂ gas, contents of Al, Ca and Ti are 0.42%, 0.014% and 0.094%, respectively; meanwhile the removal efficiency of Al, Ca and Ti are 62.16%, 95.48% and 14.54%, respectively. The refining method of blowing Ar-O₂gas can effectively remove impurity elements of Al and Ca in the ferrosilicon alloy, while no significant change in Ti content is found.

Self-healing polymer materials are able to self-repair damage and recover themselves after cracks generating to maintain their structural and functional integrity. According to whether additional repair agent is added, self-healing polymers are mainly divided into two categories, namely extrinsic- and intrinsic-based polymers.The key materials of electrochemical energy storage devices will experience irreversible mechanical damage in extreme condition applications, for example, the energy storage device more prone to physical damage inwearable devices during the multiple bending and deformation processes. These problems severely reduce the stability of energy storage and delivery, and shorten the life of the devices. Therefore, the application of self-healing polymers in electrochemical energy storage devices to improve the stability and life of devices has become one of the research hotspots in recent years. Herein,this article summarizes the repair mechanism of self-healing polymer materials (capsule-based, vascular-based, and intrinsic polymers), with main focus on intrinsic self-healing polymer and its research progress in the field of electrochemical energy storage, which based on molecular interactions to achieve multi-time reversible healing without any additional repair agent.The self-healing electrode and electrolyte system were reviewed respectively, and then the self-healing mechanism and its influence on the electrochemical performance of energy storage devices were described. The research progress of self-healing functional polymer as high specific energy electrode binder, interface modification layer and self-healing electrolyte were summarized in detail. Finally, the future perspectives regarding the future development of self-healing polymer materials were also discussed.

The refractory high-entropy alloys (RHEAs) usually form a multi-principal elements alloy with equal atomic ratio or near equal atomic ratio <i>via</i> adding a variety of high melting point elements, showing simple phase composition and excellent high temperature properties, and processing a broad application prospect in the field of superalloy. Based on the performance characteristics and preparation process of RHEAs, and from the perspective of the current situation and challenges in fabrication and forming, the property tuning methods and its research progress of RHEAs were summarized, as well as the achieved breakthrough and the facing dilemma of the additive manufactured RHEAs. A prospection on the composition design and optimization, material preparation and processing, and additive manufactured forming of RHEAs was also proposed.The following suggestions are put forward for the key research trend of RHEAs in the future: tuning phase composition and phases interface to overcome the strength-ductility trade-off of RHEAs, designing alloys by combining the mature traditional strengthening and toughening theory with the properties of RHEAs, modifying the formability and properties of RHEAs by drawing support from the processing characteristics of additive manufacturing technology, and investigating the servicing performance and failure mechanism in high temperature or multi-field coupling condition of RHEAs.

Among the manufacturing methods of high performance gradient functional materials, laser additive manufacturing technology can achieve the materials with gradient microstructure and property through precisely controlling the powder feeding and corresponding process adjustment, providing a new way to prepare high performance gradient functional materials more conveniently and efficiently. The basic principles and classification of laser additive manufacturing technology for high performance gradient functional materials were introduced in this paper, and the research progress in manufacturing high performance gradient functional materials by laser additive manufacturing technology at home and abroad was summarized. Furthermore, the shortcomings of this research field in material selection, process optimization and process monitoring were proposed, and its future research directions, such as the establishment of standard systems, in-depth theoretical research and the development of new manufacturing systems, were prospected, which provide guidance for the research of laser additive manufacturing technology for high performance gradient functional materials.

The physical/chemical properties and synthesis methods of nanoparticles were briefly introduced, and then the type and principle of the self-assembly of nanoparticles were discussed in detail. The research progress in the application of the nanoparticle self-assembly in lithium-ion batteries was summarized, and the existing problems such as the low production efficiency and high pollution in this field were also pointed out. The future works will be focused on developing approp-riate building blocks, disclosing the self-organization mechanisms and simplifying the fabrication processes, and the simultaneous yet effective adjustion of the self-assembly processes in the materials synthesis stage for advanced battery components with hierarchical structures or functions is one of the most important approaches.

Carbon dots(CDs) have attracted extensive attention of researchers because of their excellent fluorescence performance,low toxicity,extensive raw materials and good biocompatibility.However,the emission wavelengths of most CDs are in short-wavelength region of blue and green light,limiting their widespread application.The synthesis of multicolor CDs can guide the realization of long wavelength CDs and broaden the application of CDs.Therefore, the multicolor emitting mechanism of CDs from sizes,inner structures and surface states of CDs was reviewed,the adjusting measures of achieving multicolor CDs were presented,including raw materials,reaction conditions,surface modification,and separation and purification.Furthermore,the application of multicolor CDs in light emitting diode and bioimaging was also summarized.

The layered double hydroxides become research hot spot of oxygen evolution catalyzer for its easy preparation, feasible moderation of interlayer object,low cost and good stability but due to its low transmission speed of its electric charge,higher overpotential, so the modification is needed before mass application. The constructional character of the layered twinned material was firstly introduced, the catalytic mechanism of its oxygen evolution reaction was briefly described, then different kinds of optimization modification strategies to enhance its catalytic activity were introduced. The optimization modification strategies include:combination with conductive substrate, synthesis ultrathin nanometer plate, graphene compounding process, hybrid modification. The application of the stratified dihydride oxygen evolution catalyst in electrolysis of water to hydrogen and the advantages and disadvantages of different modification methods were put forward. The better-efficient oxygen evolution catalyst can be achieved through different kinds of modification. In the end, the difficulties in this kind of catalyzer were pointed out, including low recycle rate, catalyst stability, current density not meeting the requirements of industrialization and massive production.

A series of copolymers (P(AA-co-MPC)) with acrylic acid (AA) and 2-methacryloy-loxyethyl phosphorylcholine (MPC) monomers were synthesized <i>via</i> RAFT polymerization. Then the magnetic iron oxide nanoparticles were modified by these synthesized copolymers through chemical coprecipitation method. Copolymers and the nanoparticles were characterized by ¹H NMR, FTIR, GPC, TG, TEM, XRD, Zeta potential and particle size analyser, and Squid-VSM magnetic measure system. The results show that the P(AA-co-MPC) with narrow molecular mass distribution is successfully synthesized by RAFT polymerization and the surface of the magnetic iron oxide nanoparticles is modified by these copolymers. The modified magnetic iron oxide nanoparticles by copolymer synthesized with the monomer molar ratio of AA:MPC of 1:1 exhibit the best dispersion, the smallest hydrodynamic particle size (36.54&#177;4.00) nm, the narrowest particle size distribution and the highest Zeta potential (-30.98&#177;1.25) mV. The saturation magnetization is 65.57A&#183;m²&#183;kg^-1. The nanoparticles show superparamagnetism, with no residual magnetism and zero coercive force.

Graphene, as a rising star in materials science, is intensively studied in Li-ion batteries and supercapacitors, owing to its unique structure and excellent properties. The research status of the application of graphene in energy storage field was disscussed and the future development trend was predicted, and therefore to enhance the understanding of the structure-performance relationship of graphene and also the application of graphene in this field. Firstly, the application of graphene in cathode and anode of Li-ion battery, and the application of graphene in electrical double-layer capacitor and pseudo-capacitor were introduced. Secondly, the challenges of graphene in electrical double-layer capacitor were discussed and the ideal structure of graphene applied to electrical double-layer capacitor was proposed. Finally, the "three steps" to realize the commercial application of graphene-based electrical double-layer capacitor were put forward.