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As the main means of mastication, teeth can withstand countless functional contacts. The mechanical properties of teeth are closely related to their tissue structure. Enamel and dentin have a high hardness and modulus of elasticity, and their graded structure allows them to withstand bite forces without being susceptible to fracture. When tooth tissue is defective, full crown restoration is often needed to restore the normal shape and function of the tooth. Metal materials, ceramic materials, and polyetheretherketone (PEEK) materials are commonly used for crown restoration. Metal materials have certain disadvantages in terms of aesthetics and are relatively rarely used in clinical practice. Ceramic materials with different compositions exhibit differences in performance and aesthetics, but their elastic modulus and hardness are much higher than those of dental tissue, resulting in mismatching mechanical properties. In contrast, the elastic modulus of PEEK is lower than that of tooth tissue and similar to that of bone tissue, but its properties can be improved by fiber reinforcement. Notably, when the mechanical properties of a restoration material and tooth tissue are not fully matched, the interface between them often forms a potential weak link, which ultimately affects the stability and long-term effect of the restoration. This article introduces the mechanical properties and corresponding structural characteristics of enamel and dentin. On this basis, the advantages and limitations of existing restoration materials are analyzed, and the possibility of biomimetic design of full crowns is further explored.

Bristles in the first few rows float up from the rotor surface due to the radial airflow in the gap between the front plate and bristle pack, which directly affects seal performance and the service life of a brush seal. In this paper, firstly, two three-dimensional transient calculation models for a traditional brush seal (TBS) and a brush seal with disturbance-suppressing holes (DSBS) are established, respectively, based on the arbitrary Lagrange–Eulerian (ALE) method to study bristle deformation characteristics and leakage flow characteristics of the seals. Furthermore, effects of disturbance-suppressing (DS) hole structural parameters (i.e., height, diameter, and number of hole rows) were investigated to reveal the suppression mechanism of the DS holes on the buoyancy effect of bristles. The results showed that as soon as free ends of bristles at the first few rows moved along direction of the front plate in response to the radial airflow from the gap between front plate and bristle pack, a buoyancy effect of bristles occurred. The DSBS with DS holes set in the front plate of the TBS had a lower deformation of the bristles and a lower leakage amount of seal compared with that of TBS, indicating a good suppression to the buoyancy effect. With decreasing hole height and increasing hole diameter and number of hole rows, the suppression of bristle disturbance gradually increased due to decreases of the radial airflow and increases of torque acting on the bristles. [ABSTRACT FROM AUTHOR]

Transition metal oxide magnetite (Fe3O4) is recognized as a potential anode material for lithium-ion batteries owing to its high theoretical specific capacity, modest voltage output, and eco-friendly character. It is a challenging task to engineer high-performance composite materials by effectively dispersing Fe3O4 crystals with limited sizes in a well-designed supporting framework following sustainable approaches. In this work, the naturally abundant plant products sodium lignosulfonate (Lig) and sodium cellulose (CMC) were selected to coprecipitate with Fe3+ ions under mild hydrothermal conditions. The Fe-Lig/CMC intermediate sediment with an optimized microstructure can be directly converted to the Lig/CMC-derived carbon matrix-supported Fe3O4 nanocomposite sample (Fe3O4@LigC/CC). Compared with the controlled Fe3O4@LigC material, the Fe3O4@LigC/CC nanocomposite provides superior electrochemical performance in the anode, which has inspiring specific capacities of 820.6 mAh g−1 after 100 cycles under a current rate of 100 mA·g−1 and 750.5 mAh g−1 after 250 cycles, as well as more exciting rate capabilities. The biomimetic sample design and synthesis protocol closely follow the criteria of green chemistry and can be further developed in wider scenarios. [ABSTRACT FROM AUTHOR]

Organic bipolar electrodes can undergo both n‐type and p‐type reactions for energy storage due to numerous active sites, which can usually deliver a high theoretical specific capacity. Herein, a new bipolar polymer cathode material PQPZ is designed and synthesized. The electron‐donating phenazine group undergoes a two‐electron redox reaction which can store anions, the electron‐withdrawing phenanthraquinone can store sodium‐ions through a two‐electron redox reaction. Notably, as a bipolar cathode material for sodium‐ion batteries, PQPZ exhibits a reversible specific capacity of up to 270 mAh g−1 in the voltage range of 1.0–4.0 V (vs. Na+/Na) and achieves a high energy density of 696 Wh kg−1 in a half‐cell. A capacity retention rate of 90% is obtained after 300 cycles at a current density of 0.5C. More excitingly, even after being cycled for 10000 cycles at 10C, the PQPZ electrode shows an average decay rate as low as 0.0036% per cycle, manifesting a very stable cycling performance. In addition, PQPZ also shows excellent performances when tested at −10 °C, making it promising in practical applications. Considering the bipolar character of PQPZ, symmetric batteries are also successfully constructed, fulfilling the “ready‐to‐charge” property without a pre‐activation process. The results reveal the potential application of PQPZ in practical use. [ABSTRACT FROM AUTHOR]