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Objective To evaluate the applicability of a modified U-shaped forearm flap for the repair of small- and medium-sized defects in the oral and maxillary areas to provide a reference for clinicians. Methods This study was reviewed and approved by the Ethics Committee, and informed consent was obtained from the patients. Ten patients with small- and medium-sized defects in the oral and maxillary areas underwent surgical repair using modified U-shaped forearm flaps. There were 8 males and 2 females aged 43-72 years. The donor site was apposed primarily after harvesting the modified U-shaped forearm skin flap. The flaps ranged from 6 cm × 4 cm to 8 cm × 5 cm in size. Six months after the operation, hand movements (finger extension, fist clenching, wrist rotation upward and wrist rotation downward), the forearm donor site, hand sensations and the satisfaction score for the postoperative quality of the scar at the donor site were evaluated (0 to 10; 0: very unattractive, 10: very satisfactory). Results A total of 10 patients with modified U-shaped forearm flaps survived. One patient developed venous crisis 24 hours after surgery and survived after surgical exploration. Delayed healing occurred at the donor site of the forearm in 1 patient, and the wounds at the donor site of the forearm in the other patients all healed in the first stage. One patient presented with dysesthesia in the hand 2 weeks after surgery and recovered within 3 months. Six months after surgery, all patients had no limited hand movement and no paresthesia at the forearm donor site or hand. The patients were basically satisfied with the appearance of the donor site,and the average satisfaction score of the subjective questionnaire was 8.4 points. Conclusion Modified U-shaped forearm flaps can directly close forearm donor site wounds, which avoids surgical trauma to the secondary donor site and significantly reduces related complications. Modified U-shaped forearm flaps provide an alternative to conventional forearm flaps for the repair of small- and medium-sized defects in the oral and maxillary areas.

Dung beetle leg joints exhibit a remarkable capacity to support substantial loads, which is a capability significantly influenced by their surface microstructure. The exploration of biomimetic designs inspired by the surface microstructure of these joints holds potential for the development of efficient self-locking structures. However, there is a notable absence of research focused on the surface microstructure of dung beetle leg joints. In this study, we investigated the structural characteristics of the surface microstructures present in dung beetle leg joints, identifying the presence of fish-scale-like, brush-like, and spike-like microstructures on the tibia and femur. Utilizing these surface microstructural characteristics, we designed a self-locking structure that successfully demonstrated functionality in both the rotational direction of the structure and self-locking in the reverse direction. At a temperature of 20 °C, the biomimetic closure featuring a self-locking mechanism was capable of generating a self-locking force of 18 N. The bionic intelligent joint, characterized by its unique surface microstructure, presents significant potential applications in aerospace and various engineering domains, particularly as a critical component in folding mechanisms. This research offers innovative design concepts for folding mechanisms, such as those utilized in satellite solar panels and solar panels for asteroid probes. [ABSTRACT FROM AUTHOR]

Beetle femur–tibial joints can bear large loads, and the joint structure plays a crucial role. Differences in living habits will lead to differences in femur–tibial joint structure, resulting in different mechanical properties. Here, we determined the structural characteristics of the femur–tibial joints of three species of beetles with different living habits. The tibia of Scarabaeidae Protaetia brevitarsis and Cetoniidae Torynorrhina fulvopilosa slide through cashew-shaped bumps on both sides of the femur in a guide rail consisting of a ring and a cone bump. The femur–tibial joint of Buprestidae Chrysodema radians is composed of a conical convex tibia and a circular concave femur. A bionic structure design was developed out based on the characteristics of the structure of the femur–tibial joints. Differences in the failure of different joint models were obtained through experiments and finite element analysis. The experimental results show that although the spherical connection model can bear low loads, it can maintain partial integrity of the structure and avoid complete failure. The cuboid connection model shows a higher load-bearing capacity, but its failure mode is irreversible deformation. As key parts of rotatable mechanisms, the bionic models have the potential for wide application in the high-load engineering field. [ABSTRACT FROM AUTHOR]

Based on the laminar composite structure, the hardness distribution pattern and crack arrest property of Rapana venosa shell, bionic layered composite materials were prepared via hot-pressing sintering by using B4C/5083Al system and pure 5083Al as materials. The microstructure and mechanical properties were investigated by scanning electron microscope (SEM) and universal tester. The results show that on the macroscopic level, the bionic layered composite material has a multi-layered structure which is composed of hard layer of B4C/5083Al and flexible layer of 5083Al. The bionic composites exhibit “soft and hard” distribution characteristic of hardness. On the microscopic level, the hard layer of B4C/5083Al consists of B4C and 5083Al matrix, and B4C is staggered and interlinked in 5083Al matrix with combination of "soft and hard" properties. The bionic layered composites own higher compressive strength and impact toughness, and the layered overlapping structure can reset the direction of crack in the next layer, which lead the crack deflection phenomena and high impact resistance.

Fiber-reinforced composites are an ideal high-performance composite material made from a combination of high-strength continuous fibers and a polymer matrix. Compared to short cut fibers, continuous long strand fibers can improve the mechanical properties of fiber composites more effectively. Herein, continuous aramid fiber-reinforced PLA filaments with fiber centering were prepared by modifying the outlet design of a desktop-grade thermoplastic single-screw melt extruder. Inspired by the cross-laminated structure of a beetle's mandible fibers, a biomimetic structure composite was printed, which demonstrates a significant influence on the mechanical properties. The G-code printing program was developed, and the microstructure of the fracture surface of the specimen was analyzed. The uniform and orderly arrangement of aramid fibers within the PLA resin-based 3D-printed specimen was found. Consequentially, the bionic composites exhibits a 12% increase in tensile strength and a 5% increase in impact toughness, confirming the feasibility of utilizing continuous 3D printing to manufacture long bundles of aramid fiber composite filaments for enhanced mechanical performances. [ABSTRACT FROM AUTHOR]