[Preparation of vascularized forearm dermal fat flap and repairing of donor site].

Objective:This study prepared vascularized dermal fat flaps and introduced a local split-thickness skin graft from an in situ cutaneous area cutaneous area to manage forearm flap donor sites and evaluated the esthetic and functional outcomes post-operatively. From July 2020 to June 2023, 13 patients with soft tissue defects in Oral and Maxillary Area were repaired with tvascular forearm dermal fat flap. There were 8 males and 5 females, aged from 42-71 years. The flaps ranged from 8 cm×7 cm to 7 cm×5 cm in size. The donor site defects were covered by local split-thickness skin graft from the in situ skins. The color matching degree, surgical scars, ranges of wrist movement and hand sensations in donor forearms were assessed at 6 months after surgery. Results:The tvascular forearm dermal fat flaps for 15 cases all survived. All the local split-thickness skin grafts transplanted with this technique showed primary healing. The follow-up period for 6 months, Donor site exhibited suitabler color matching and there was not severe complications. Conclusion:The vascularized dermal fat flap provides an alternative to conventional forearm flap harvest, which enables primary donor site closure with reduced rates of delayed donor site healing. The vascularized dermal fat flap is a relatively reliable repair method for soft defects in Oral and Maxillary Area.

Bionic Design of High-Performance Joints: Differences in Failure Mechanisms Caused by the Different Structures of Beetle Femur-Tibial Joints.

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.

Study of Self-Locking Structure Based on Surface Microstructure of Dung Beetle Leg Joint.

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.

[Application of free forearm flap in reconstruction of postoperative defect of external nasal malignant tumor].

Objective:To investigate the therapeutic effect of free forearm flaps in repairing the postoperative defect of external nasal malignant tumor. Methods:Six patients with nasal malignant tumor were treated with radical operation of external nasal malignant tumor and simultaneous reconstruction of external nasal defects with free forearm flap. Preoperative Allen experiment, ultrasonic Doppler blood flow meter or CT angiography confirmed that the forearm blood vessels were in good condition. Results:The free forearm flaps were obtained from six patients, and completely survived. During the follow-up period of 6-12months, all patients had good external nasal morphology, good nasal function, no nasal obstruction and anterior nostril stenosis, no obvious complications in donor hand and no local cancer recurrence. Conclusion:The free forearm flap is a reliable method to reconstruction the postoperative defect of external nasal malignant tumor, with a high success rate and good recovery of morphology and function recovery.

Study of the influence of macro-structure and micro-structure on the mechanical properties of stag beetle upper jaw.

Macrostructural control of stress distribution and microstructural influence on crack propagation is one of the strategies for obtaining high mechanical properties in stag beetle upper jaws. The maximum bending fracture force of the stag beetle upper jaw is approximately 154, 000 times the weight of the upper jaw. Here, we explore the macro and micro-structural characteristics of two stag beetle upper jaws and reveal the resulting differences in mechanical properties and enhancement mechanisms. At the macroscopic level, the elliptic and triangular cross-sections of the upper jaw of the two species of stag beetles have significant effects on the formation of cracks. The crack generated by the upper jaws with a triangular section grows slowly and deflects easily. At the microscopic level, the upper jaw of the two species is a chitin cross-layered structure, but the difference between the two adjacent fiber layers at 45° and 50° leads to different deflection paths of the cracks on the exoskeleton. The mechanical properties of the upper jaw of the two species of stag beetle were significantly different due to the interaction of macro-structure and micro-structure. In addition, a series of bionic samples with different cross-section geometries and different fiber cross angles were designed, and mechanical tests were carried out according to the macro-structure and micro-structure characteristics of the stag beetle upper jaw. The effects of cross-section geometry and fiber cross angle on the mechanical properties of bionic samples are compared and analyzed. This study provides new ideas for designing and optimizing highly loaded components in engineering. STATEMENT OF SIGNIFICANCE: The upper jaw of the stag beetle is composed of a complex arrangement of chitin and protein fibers, providing both rigidity and flexibility. This structure is designed to withstand various mechanical stresses, including impacts and bending forces, encountered during its burrowing activities and interactions with its environment. The study of the upper jaw of the stag beetle can provide an efficient structural design for engineering components that are subjected to high loads. Understanding the relationship between structure and mechanical properties in the stag beetle upper jaw holds significant implications for biomimetic design and engineering.

Soft Actuator with Biomass Porous Electrode: A Strategy for Lowering Voltage and Enhancing Durability.

Electroactive artificial muscles with deformability have attracted widespread interest in the field of soft robotics. However, the design of artificial muscles with low-driven voltage and operational durability remains challenging. Herein, novel biomass porous carbon (BPC) electrodes are proposed. The nanoporous BPC enables the electrode to provide exposed active surfaces for charge transfer and unimpeded channels for ion migration, thus decreasing the driving voltage, enhancing time durability, and maintaining the actuation performances simultaneously. The proposed actuator exhibits a high displacement of 13.6 mm (bending strain of 0.54%) under 0.5 V and long-term durability of 99.3% retention after 550,000 cycles (∼13 days) without breaks. Further, the actuators are integrated to perform soft touch on a smartphone and demonstrated as bioinspired robots, including a bionic butterfly and a crawling robot (moving speed = 0.08 BL s-1). This strategy provides new insight into the design and fabrication of high-performance electroactive soft actuators with great application potential.

Multi-Level Structural Enhancement Mechanism of the Excellent Mechanical Properties of Dung Beetle Leg Joint.

The multi-level structure is a strategy to enhance the mechanical properties of dung beetle leg joints. Under external loads, the microstructure facilitates energy dissipation and prevents crack extension. The macrostructure aids in transferring the load to more reliable parts. The connection established by the two hemispheres is present in the dung beetle leg joint. The micron-layered and nanoscale crystal structures further constitute the leg joint with excellent mechanical properties. The maximum compression fracture force is ≈101000 times the weight of the leg. Here, the structural design within the dung beetle leg joints and reveal the resulting mechanical response and enhancement mechanisms is determined. A series of beetle leg joints where the macrostructure and microstructure of the dung beetle leg provide mechanical strength at critical strains while avoiding catastrophic failure by transferring the load from the joint to the exoskeleton of the femur is highlighted. Nanocrystalline structures and fiber layers contribute to crack propagation of the exoskeleton. Based on this, the bionic joint with multi-level structures using resin and conducted a series of tests to verify their effectiveness is prepared. This study provides a new idea for designing and optimizing high-load joints in engineering.

Bio-Inspired Interlocking Structures for Enhancing Flexible Coatings Adhesion.

The flexible protective coatings and substrates frequently exhibit unstable bonding in industrial applications. For strong interfacial adhesion of heterogeneous materials and long-lasting adhesion of flexible protective coatings even in harsh corrosive environments. Inspired by the interdigitated structures in Phloeodes diabolicus elytra, a straightforward magnetic molding technique is employed to create an interlocking microarray for reinforced heterogeneous assembly. Benefiting from this bio-inspired microarrays, the interlocking polydimethylsiloxane (PDMS) coating recorded a 270% improvement in tensile adhesion and a 520% increase in shear resistance, approaching the tensile limitation of PDMS. The elastic polyurethane-polyamide (PUPI) coating equipped with interlocking structures demonstrated a robust adhesion strength exceeding 10.8 MPa and is nearly unaffected by the corrosion immersion. In sharp contrast, its unmodified counterpart exhibited low initial adhesion and maintain ≈20% of its adhesion strength after 30 d of immersion. PUPI coating integrated with microarrays exhibits superior resistance to corrosion (30 d, |Z|0.01HZ ≈1010 Ω cm2, Rct≈108 Ω cm2), cavitation and long-term adhesion retention. These interlocking designs can also be adapted to curved surfaces by 3D printing and enhances heterogeneous assembly of non-bonded materials like polyvinylidene fluoride (PTFE) and PDMS. This bio-inspired interlocking structures offers a solution for durably bonding incompatible interfaces across varied engineering applications.

Exogenous GDNF promotes peripheral facial nerve regeneration in rats through the PI3K/AKT/mTOR signaling pathway.

Facial nerve regeneration still lacks a well-defined and practical clinical intervention. The survival of central facial motoneuron is a critical component in the successful peripheral facial nerve regeneration. Endogenous GDNF is vital for facial nerve regeneration according to earlier investigations. Nevertheless, the low endogenous GDNF level makes it challenging to achieve therapeutic benefits. Thus, we crushed the main trunk of facial nerve in SD rats to provide a model of peripheral facial paralysis, and we administered exogenous GDNF and Rapa treatments. We observed changes in the animal behavior scores, the morphology of facial nerve and buccinator muscle, the electrophysiological of facial nerve, and the expression of GDNF, GAP-43, and PI3K/AKT/mTOR signaling pathway-related molecules in the facial motoneurons. We discovered that GDNF could boost axon regeneration, hasten the recovery of facial paralysis symptoms and nerve conduction function, and increase the expression of GDNF, GAP-43, and PI3K/AKT/mTOR signaling pathway-related molecules in the central facial motoneurons. Therefore, exogenous GDNF injection into the buccinator muscle can enhance facial nerve regeneration following crushing injury and protect facial neurons via the PI3K/AKT/mTOR signaling pathway. This will offer a fresh perspective and theoretical foundation for the management of clinical facial nerve regeneration.

Study on Design and Preparation of Conductive Polyvinylidene Fluoride Fibrous Membrane with High Conductivity via Electrostatic Spinning.

The novel conductive polyvinylidene fluoride (PVDF) fibrous membrane with high conductivity and sensitivity was successfully prepared via electrostatic spinning and efficient silver reduction technology. Based on the selective dissolution of porogen of polyvinylpyrrolidone (PVP), the porous PVDF fibrous membrane with excellent adsorbability and mechanical strength was obtained, providing a structure base for the preparation of conductive PVDF fibrous membrane with silver nanoparticles (AgNPs-PVDF). The Ag+ in the AgNO3 mixed solution with PVP was absorbed and maintained in the inner parts and surface of the porous structure. After the reducing action of ascorbic acid-mixed solution with PVP, silver nanoparticles were obtained tightly in an original porous PVDF fibrous membrane, realizing the maximum conductivity of 2500 S/m. With combined excellent conductivity and mechanical strength, the AgNPs-PVDF fibrous membrane effectively and sensitively detected strain signals of throat vocalization, elbow, wrist, finger, and knee (gauge factor of 23). The electrospun conductive AgNPs-PVDF combined the characteristics of low resistance, high mechanical strength, and soft breathability, which provided a new and effective preparation method of conductive fibers for practical application in wearable devices.

Composite Flexible Sensor Based on Bionic Microstructure to Simultaneously Monitor Pressure and Strain.

To achieve the human sense of touch, a strain sensor needs to be coupled with a pressure sensor to identify the compliance of the contacted material. However, monitoring the pressure-strain signals simultaneously and ensuring no coupling effect between the two signals is the technical bottleneck for the flexible tactile sensor to. Herein, a composite flexible sensor based on microstructures of lotus leaf is designed and manufactured, which integrates the capacitive pressure sensor and the resistance strain sensor into one pixel to realize the simultaneous detection of pressure and strain. The electrode layer of the capacitance sensor also plays the role of the resistance strain sensor, which greatly simplifies the structure of the composite flexible sensor and obtains the compact size to integrate more easily. The device can simultaneously detect pressure and deformation, and more importantly, there is no coupling effect between the two kinds of signals. Here, the sensor has high pressure sensitivity (0.784 kPa-1 when pressure less than 100 kPa), high strain sensitivity (gauge factor = 4.03 for strain 0-40%), and can identify materials with different compliance, which indicates the tactile ability as the human skin performs.

Continuous 3D Printing of Biomimetic Beetle Mandible Structure with Long Bundles of Aramid Fiber Composites.

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.

Low-Voltage Driven Ionic Polymer-Metal Composite Actuators: Structures, Materials, and Applications.

With the characteristics of low driving voltage, light weight, and flexibility, ionic polymer-metal composites (IPMCs) have attracted much attention as excellent candidates for artificial muscle materials in the fields of biomedical devices, flexible robots, and microelectromechanical systems. Under small voltage excitation, ions inside the IPMC proton exchange membrane migrate directionally, leading to differences in the expansion rate of the cathode and the anode, which in turn deform. This behavior is caused by the synergistic action of a three-layer structure consisting of an external electrode layer and an internal proton exchange membrane, but the electrode layer is more dominant in this process due to the migration and storage of ions. The exploration of modifications and alternatives for proton exchange membranes and recent advances in the fabrication and characterization of conductive materials, especially carbon-based materials and conductive polymers, have contributed significantly to the development of IPMCs. This paper reviews the progress in the application of proton exchange membranes and electrode materials for IPMCs, discusses various processes currently applied to IPMCs preparation, and introduces various promising applications of cutting-edge IPMCs with high performance to provide new ideas and approaches for the research of  new generation of low-voltage ionic soft actuators.

Bouncing dynamics of impact droplets on bioinspired surfaces with mixed wettability and directional transport control.

Kingfishers stand on a branch, and raindrops tumble translationally from feathers during raining, enlightening functional surfaces design and liquid transport control. Far-ranging studies on oriented transportation are confined to vertical impacting, which is, to date, in-depth philosophy of horizontal droplets transport on motionless surface deems to be rather serviceable. This study, employed mixed-wettability surface inspired by kingfishers' feather, occurs on directional transportation issues, such as the synergies of wettability-controlled, driving force and transportation capability. Here we conduct both experimental testing and CFD-aided numerical modelling to reproduce the asymmetric bouncing and directional transport phenomena. We found that the anisotropic surface manipulates to convert normally vertical impacting to horizontal droplets transport. Law of the thrown droplet, on the other hand, is predominated by the wettability-controlled surface, while the coexistence of contact angle difference and surface offset location cooperatively dictates the intensity and patterns of the thrown droplet. Of all these factors, the post-optimized surfaces are designed first and then the regime map of transportation pattern is elaborated. Results manifest that the elements induce the maximum horizontal transport distance by up to 6.2D0, and first desorption time is only 7.8 ms. The findings shed light on engineering design principles that can pave the way for novel applications in anti-icing, lubrication, and spray cooling.

Bio-Design, Fabrication and Analysis of a Flexible Valve.

Fluid-driven soft robots offer many advantages over robots driven by other means in terms of universal preparation processes and high-power density ratios, but are largely limited by their inherit characteristics of rigid pressure sources, fluid control elements and complex fluid pipelines. In this paper, inspired by the principle of biofluid control and actuation, we combine simulation analysis and experimental validation to conduct a bionic design study of an efficient flexible fluid control valve with different actuation diaphragm structures. Under critical flexural load, the flexible valve undergoes a continuous flexural instability overturning process, generating a wide range of displacements. The sensitivity of the flexible valve can be improved by adjusting the diaphragm geometry parameters. The results show that the diaphragm wall thickness is positively correlated with the overturning critical pressure, and the radius of curvature is negatively correlated with the overturning critical pressure. When the wall thickness of the flexible valve maintains the same value, as the radius of curvature increases, the critical buckling load and recovery load of diaphragm overturning is a quadratic function of opposite opening, and the pressure difference converges to the minimum value at the radius of curvature R = 7.

Effects of Cathepsins on Gel Strength and Water-Holding Capacity of Myofibrillar Protein Gels from Bighead Carp (Aristichthys nobilis) under a Hydroxyl Radical-Generation Oxidizing System.

This study investigates the effects of cathepsins on the gel strength and water-holding capacity (WHC) of myofibrillar protein gels from bighead carp (Aristichthys nobilis) under a hydroxyl radical-generation oxidizing system. The myofibrillar proteins were divided into control group (with cathepsins) and E64 group (without cathepsins). The changes of cathepsin B and cathepsin L activities, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), protein oxidation (total sulfhydryl and carbonyl contents), and chemical interactions (nonspecific association, ionic bonds, hydrogen bonds, hydrophobic interactions, and disulfides) of myofibrillar protein and gels, as well as the gel strength and WHC of two groups under 0-100 mM H2O2, were measured. The results indicated that mild oxidation (10 mM H2O2) made a better gel strength and WHC. Cathepsin B and L activities decreased with increasing H2O2 concentrations but their effects on myofibrillar protein degradation still existed during 0.1-50 mM H2O2, which was expressed by higher carbonyl contents and ionic bonds at 0.1 and 50 mM H2O2, higher total sulfhydryl contents at 0 mM H2O2, and a lower intensity of MHC and actin of the control group than the E64 group. Besides more protein degradation, cathepsin proteolysis also resulted in lower gel strength and WHC in control gels than E64 gels under mild oxidation, which could be explained by lower hydrophobic interaction and moderate disulfides bonds between gel protein molecules of control gels.

Ethanol Phase Change Actuator Based on Thermally Conductive Material for Fast Cycle Actuation.

Artificial muscle actuator has been devoted to replicate the function of biological muscles, playing an important part of an emerging field at inter-section of bionic, mechanical, and material disciplines. Most of these artificial muscles possess their own unique functionality and irreplaceability, but also have some disadvantages and shortcomings. Among those, phase change type artificial muscles gain particular attentions, owing to the merits of easy processing, convenient controlling, non-toxic and fast-response. Herein, we prepared a silicon/ethanol/(graphene oxide/gold nanoparticles) composite elastic actuator for soft actuation. The functional properties are discussed in terms of microstructure, mechanical properties, thermal imaging and mechanical actuation characteristics, respectively. The added graphene oxide and Au nanoparticles can effectively accelerate the heating rate of material and improve its mechanical properties, thus increasing the vaporization rate of ethanol, which helps to accelerate the deformation rate and enhance the actuation capability. As part of the study, we also tested the performance of composite elastomers containing different concentrations of graphene oxide to identify GO-15 (15 mg of graphene oxide per 7.2 mL of material) flexible actuators as the best composition with a driving force up to 1.68 N.

Modeling relationship between protein oxidation and denaturation and texture, moisture loss of bighead carp (Aristichthys Nobilis) during frozen storage.

To evaluate the effects of protein oxidation and denaturation on the fish texture and moisture loss during frozen storage, we measured the changes of protein oxidation and denaturation (salt-soluble protein (SSP), total sulfhydryl (SH), disulfide (SS), carbonyl contents and Ca2+ -ATPase activity), texture (hardness), and moisture loss (drip loss) of bighead carp fillets stored at -12, -20 and -28°C during 16 weeks. These data were employed to develop partial least squares regression (PLSR) model, radial basis function neural network (RBFNN) model, PLSR-RBFNN (PR) model and RBFNN-PLSR (RP) model. The results showed that the RP model provided no enhancement to RBFNN model because it had the exactly same root mean square error (RMSE) and R2 . PLSR model showed better performance than other models when predicting hardness. More appropriate linear or linearity-dominant hybrid model needed to be explored to establish the relationship between protein oxidation and denaturation and texture. The PR model performed better than other models in predicting drip loss with its lower RMSE and higher R2 , which revealed both linear and nonlinear relationship between protein oxidation and denaturation and moisture loss. Therefore, the PR model was a promising and encouraging tool to provide a more comprehensive understanding of the relationship between protein oxidation and denaturation and moisture loss of fish during frozen storage. PRACTICAL APPLICATION: The study explored the effects of protein oxidation and denaturation on the texture and moisture loss of bighead carp during frozen storage (-12 to -28°C). PLSR model showed better performance than other models when predicting the relationship between protein oxidation and denaturation and texture. The PR model was an available tool for manufacturers to predict the relationship between protein oxidation and denaturation and moisture loss.

Bionic Design and 3D Printing of Continuous Carbon Fiber-Reinforced Polylactic Acid Composite with Barbicel Structure of Eagle-Owl Feather.

Inspired by eagle-owl feather with characteristics of light weight and high strength, the bionic continuous carbon fiber-reinforced polylactic acid composite with barbicel structure was successfully 3D printed. Under the action of external load, angles between barbicels and rachis structure of eagle-owl feather decreased, which consumed a part of energy and built structure base of bionic feather structure model with a certain arrangement angle of continuous carbon fiber. Variation of bionic structure model design parameters significantly affected the mechanical properties of the 3D printing bionic composites. The relatively low continuous carbon fiber content on tensile force direction restricted enhancement of tensile strength of bionic composite. However, attributed to different angle arrangement of continuous carbon fiber, the propagation of cracks in bionic composite was hindered, exhibiting high impact resistance. The effective and feasible bionic feather design and 3D printing of continuous carbon fiber-reinforced polylactic acid composite extended the corresponding application in the areas with high impact loads.