The increasing occurrence of hot summer days causes stress for both humans and animals, particularly in urban areas where temperatures remain high, even at night. Nature offers potential solutions that require minimal energy and material costs. For instance, the Saharan silver ant can endure the desert heat by means of passive radiative cooling induced by its triangular hairs. Shi et al. experimentally demonstrated this effect. The aim of this project is to transfer the structural cooling property of the Ant to various surfaces using an epoxy mould or stamp. Shrimp shells are chosen as the first target surface due to their low cost (as a waste product), biodegradability, and similarity in material to the ants' bodies (Chitin).
In the initial phase of the project, shrimp shells are scratched with a diamond tip. Some of the samples are subjected to simulated hot and cold climates inside a climate chamber for three weeks. Comparing the exposed to the unexposed samples provides insight into the weatherability of the shells. The measurements are carried out with optical, confocal, and electron microscopy.
In the second part, a stamp of the silver ant's surface is manufactured using the process described in the paper by Zobl et al. This stamp is used to modify the shrimp shell surface, with the aim of increasing its emissivity. We want to show that it is possible to decrease the surface temperature purely through functionalities induced via structural modification. This shall then be scaled up for larger surfaces, such as house facades, to reduce the need for conventional cooling.

The humpback whale's unique and sensitive hunting ability in the ocean is due to the leading-edge protuberances of its flippers, which is also a viable passive control method for flow separation and cavitation. In this paper, the linear leading-edge of NACA 63₄-021 foil was modified, and a bionic hydrofoil with discontinuous sinusoidal leading-edge was constructed. The wavelength and amplitude were λ=0.25C and A=0.025C, respectively, and the distance between adjacent protuberances was 0.25λ. The cavitation performances of the basic hydrofoil and the bionic hydrofoil with a cavitation number of 0.8 were numerically studied using the large eddy simulation method. The instantaneous flow characteristics of the hydrofoils were reported, including the lift and drag coefficients, pressure fluctuations, and the cavitation evolution. It was found that the flow of the discontinuous sinusoidal leading-edge hydrofoil showed obvious periodic patterns in the span direction, which changed the cavitation characteristics of the hydrofoil. The streamwise vortices induced by the protuberances restricted the incipient cavitation to the trough region and inhibited the cavitation near the peak section. Compared with the basic hydrofoil, the cavitation volume of the bionic hydrofoil was reduced by 35.94% at the 15° angle of attack, the stability of cavitation flow was stronger, and the standard deviation of pressure coefficient near the leading-edge of the suction surface was reduced by up to 50%. This study verified the feasibility of the discontinuous protuberance structure to inhibit the hydrofoil cavitation, which can provide theoretical guidance for the blade design of hydraulic machinery.

The aim of the presented research was the physicochemical characterization of a biomaterial based on chitosan, hyaluronic acid and titanium dioxide(IV) in relation to biocompatibility and antibacterial characteristics for application in the cosmetic, medical and pharmaceutical industries. Chitosan and hyaluronic acid were chosen due to their potential application (e.g., artificial skin and wound dressings), and titanium oxide(IV) was chosen to increase mechanical stability. The parameters with crucial effects on stability and biological environment response, and also those responsible for the antibacterial properties of the biomaterials, were described. The physicochemical properties of two- and three-component dispersions based on chitosan, hyaluronic acid and/or titanium oxide(IV) of different mass ratios were described in relation to energetic and topographic parameters. Knowledge of such parameters is necessary to predict and control the behavior of cells, which determines the proper functioning of the biomaterial in the living organism, indirectly providing information about biocompatibility.

The experimental data provided using the Langmuir technique, coupled with the Brewster angle microscope, gave insight into the interactions existing between the individual dispersion constituents and phospholipid molecules forming the model biological membranes. In order to characterize the biomaterial/cell membrane interactions precisely, two kinds of phospholipids which differ in their structure, 1,2-dipalmitoilo-sn-glycero-3-phosphocholine (DPPC) and 1,2-dioleoilo-sn-glycero-3- phosphocholine (DOPC), were used. Moreover, the 1,2-dipalmitoilo-sn-glycero-3-phospho-rac-(1-glycerol) sodium salt, being the typical component of bacterial Escherichia coli and Staphylococcus aureus membrane, as well as lipids extracted from these bacteria were used. The bactericidal capacity of the tested system was interpreted based on the colony forming the unit (CFU)-counting assay and LIVE/DEAD staining shared with the fluorescence intensity measurements. The obtained results significantly contribute to a broader understanding of the interactions of components of different polarities, with biological membranes confirming the need for a multifaceted view using biomimetic methods.

Biomimetic sol–gel synthesis using alkoxysilane derivatives (gel precursors) and natural polysaccharides (templates) is one of the current directions used for obtaining hybrid hydrogel materials for medical purposes.

In this work, polymeric glycerohydrogels, in the form of thin-film plates, were obtained using biomimetic sol–gel synthesis with silicon tetraglycerolate, chitosan L-(D-)aspartate (CS·L-(D-)AspA), and glucomannan. The surface microrelief of the samples was examined by atomic force microscopy, and the level of supramolecular structuring in their polymer phase was assessed by X-ray diffractometry. A comparative analysis of the adhesion, spreading, and proliferation rate in vitro of epithelial-like cells of the rhesus macaque embryonic kidney MA-104 and epithelial cells of human fibroblasts and keratinocytes in the presence of CS·L-(D-)AspA was carried out.

It has been established our glycerohydrogel plates based on CS·L-AsрA and CS·D-AsрA are represented by interpenetrating spatial networks of both organic and inorganic nature, filled with a water–glycerol medium. For the CS·L-AsрA plates, a predominantly “needle-like” relief is visualized with a predominance of protrusions up to 4.2 µm high, while a “needle-grained” relief is characteristic for the CS·D-AsрA ones with protrusions up to 2.8 µm high and pores with diameters of ~3–10 µm. The solid phase from the corresponding plates showed a dense amorphous–crystalline ordering of the polymeric substance compared to the solid phase isolated from CS·L-(D-)AspA in the absence of silicon polyolate networks and a bioinert template. The addition of CS·L-(D-)AspA to the nutrient medium to cultivate MA-104 epithelial cells, human fibroblasts, and keratinocytes accelerates the adhesive and proliferative activity in vitro of the cell cultures tested.

These features allow us to consider our glycerohydrogel plates based on CS·L-(D-)AsрA as promising biomimetic substrates to form tissue-engineered structures with a pregiven set of properties and an accelerated growth of populations of epithelial and epitheliopod cell cultures.

The ever-increasing requirements for structural performance drive the research and development of lighter, stronger, tougher, and multifunctional composite materials. In particular, porous structures, heterogeneities, and hybrid composites have attracted great interest from the materials research community. However, strong coupling among the material composition and topology of the porous structure hinders conventional trial-and-error approaches, and current technologies that rely on traditional design and manufacturing techniques are insufficient to effectively solve the pressing challenges facing future societies. This presentation aims to adopt bio-inspired design for structural applications. Bio-inspired design solutions are widely used in different engineering disciplines. However, in structural engineering, these solutions are mainly limited to bio-inspired structures or microstructures, shapes or topologies, and materials, and the applications are mainly used to optimize stiffness, strength, weight, toughness, etc. In this work, carbon fiber-reinforced polymer matrix composite materials were adopted for structural design. In addition, 2D and 3D periodic lattice blocks inspired by biomimetics combined with topological optimization based on finite element modeling and an experimental approach were proposed. Computer modeling and topology optimization, based on finite element analysis, were conducted on the periodic representative volume elements to characterize the designed lattice structural composites’ performance. The 3D printing technique was used for prototyping the bio-inspired designed porous structures, and experimental tests were carried out to validate the design methodology. The proposed approach provides a design tool for more affordable, more effective, and higher-performance structural materials.

Mycelium-based composite (MBC) consists of the filamentous fungi of mushrooms, mycelium, forming a network with biodegradable agro-waste particles. MBC can be shaped in plastic molds; however, a higher density of mycelium was observed at the MBC surface exposed to the air (MBC/Air) than the MBC contact with plastic mold (MBC/Mold). Consequently, MBC was demolded to obtain uniform growth of mycelium on the substrate. This study investigated the effect of the oxygen transmission rate (OTR) of two different thin film materials, PVC plastic food wrap and stencil paper, on the growth of the mycelium of oyster mushrooms on sawdust. Each thin film was covered between the MBC and polypropylene (PP) mold in configurations of MBC/Film/PP Mold. The OTR of thin films was measured according to ASTM D3985. The results were compared with the OTR of a rigid PVC tube, PET-G, and PP cast, which were used as molds for shaping the MBC in previous literature. It was found that the mycelium was of a higher density in MBC/PVC film/PP and MBC/stencil paper/PP than the top surface of MBC/Air. The OTRs of stencil paper and PVC film were 11,777.78 cc-mm/m²/day and 143.88 cc-mm/m²/day, respectively, which were higher than those of the rigid PVC tube (3 cc-mm/m²/day), PET-G (9.7 cc-mm/m²/day), and PP cast (76 cc-mm/m²/day). Despite the higher OTR found in stencil paper than in PVC film, the mycelium at MBC/PVC film/PP was denser than MBC/stencil paper/PP. This suggested that sufficient oxygen transmission through film contact with the MBC surface was necessary for the mycelium to grow homogeneously. Shaping the complex geometry of MBC can be possible without using the rigid plastic mold, yet only PVC plastic wrap is acceptable. The mechanical properties of MBC will be further investigated.

The design of functional paper coatings with excellent barrier properties towards water and oxygen ingress in parallel with the enhanced recyclability of the coating layer is highly demanded, in view of sustainable applications for paper as a food packaging material in the industrial context. Therefore, enhanced functionalities of the coating layers should be incorporated through a combination of selected bio-based materials and the creation of appropriate surface textures that enhance coating performance. Bio-inspired approaches, through the replication of hierarchical surface structures with multi-scale dimensional features, in combination with the selection of appropriate bio-based functional groups offer new concepts for coating design. In this overview, some of the recent advances in the field are illustrated with a focus on the combination of hydrophobic and anti-microbial coating functionalities. Based on our long-term work with an available toolbox of bio-based building blocks and nanoscale architectures, they can be processed into applicable aqueous suspensions for paper coating deposition. The macroscopic roughness profile of paper substrates can be complemented through the decoration of nanoscale bio-based polymer particles of polyhydroxybutyrate from vegetable oil capsules with dimensions in the range of 20 to 50 nm or 100 to 500 nm, depending on the synthesis conditions. The anti-microbial properties can be provided through the surface modification of nanocellulose with biologically active molecules sourced from nature. Aside from the more fundamental issues in design and synthesis, the industrial application of bio-inspired coatings under spray-coating application becomes relevant.

Otariidae are the only marine mammals that use their foreflippers for propulsion, and the combination of hydrofoil and paddle propulsion makes them excellent hunters and swimmers. Therefore, it is of great scientific significance and engineering value to develop a novel underwater propulsion technology inspired by the propulsion mode of Otariidae foreflippers. At present, research on the Otariidae foreflipper-inspired propulsion is still in the initial stage and needs to be explored further in terms of both theory and technology. The bionic underwater robot team led by Prof. Liu of Tianjin University has made some achievements in this regard. Taking the California sea lion as a bionic prototype, they developed the first-generation biomimetic robotic sea lion foreflipper propulsion mechanism (Rob-flipper-I for short). In this study, the Rob-flipper-II is developed through the optimization of the Rob-flipper-I, which is composed of a driving mechanism and a pair of bionic foreflippers. The driving mechanism consists of a wobbling disk mechanism and a spatial linkage mechanism that are connected in series, and the bionic foreflippers have similar flexibility and mechanical properties to those of the sea lion foreflippers. The Rob-flipper-II can reproduce the spatial trajectory and attitude of the sea lion foreflippers by a single drive only. Based on the kinematics analysis of the Rob-flipper-II, the formulas for calculating the thrust and lift of the bionic foreflipper are derived, and the functional relationship between the motion speed of the bionic sea lion robot and the flapping frequency of the bionic foreflippers are obtained. In addition, the propulsive efficiency of the Rob-flipper-II is calculated. The tank experiment shows that the average thrust and propulsive efficiency of the Rob-flipper-II are higher than those of the Rob-flipper-I.

^INTRODUCTION

Afforestation and reforestation (A/R) serves as the crucial cornerstone for the achievement of SDGs, effectively reversing climate change and curbing desertification. Drone-supported seed sowing (UAVsSS) represents a paradigm shift in rapid forest restoration, surpassing conventional methods [1]. However, the exploration of more advanced alternatives is necessitated by certain limitations, including a low seed survival rate (0-20%), sensitivity to high wind and precipitation, concerns about seed-firing accuracy, and adherence to country-specific aviation rules [2]. Biomimetics, drawing inspiration from nature's time-tested design for resilience, stands as the contemporary answer for complex design problems. The objective of this study is to design an inventive solution for accomplishing forest landscape restoration, guided by the principles of biomimetics.

^{MATERIALS AND METHODS}

^{Deriving inspiration from the phototrophic spore dispersal of the Pilobolus fungi, ballistic seed dispersal in Sweet Violet (Viola odorata) pods, and the adaptability of spiders in forest ecosystems, a sensor-based seed dispersal device has been designed. It is equipped with a GPS locator, light sensor, obstacle, and water surface detector. The device contains two seed chambers with native tree seeds of heliophytes and sciophytes. By constantly detecting sunlight penetration while moving on the ground, it disperses heliophyte seeds where sunlight penetrates more, and sciophyte seeds in relatively shaded zones. With spider-like maneuverability, it can navigate forest clearings, overcome obstacles like fallen trees, and even swim through water surfaces. Testing is conducted to assess its effectiveness in a simulated environment.}

^RESULTS

^{Simulation demonstrates the device's adeptness in responding to varying light penetration and circumventing obstacles. The device accomplishes targeted seed dispersal based on detected light penetration by mimicking the natural dispersal behavior of Pilobolus fungi and Viola odorata effectively.}

^CONCLUSIONS

^{The results indicate that this device presents a viable alternative for UAVsSS, providing an efficient solution for precision-based rapid afforestation.}

A wound is a defect or break in the skin caused by physical or thermal damage. Depending on the area of skin affected, there may be a series of alterations in the organism, such as blood loss, dehydration, difficulty in maintaining body temperature, or infection. The wound healing process represents a complex series of biological events to restore the skin barrier function. Numerous studies have shown that low levels of reactive oxygen species (ROS) promote normal wound healing by stimulating cell migration and angiogenesis, but excessive ROS can derive in chronic wounds. In chronic wounds, a sustained inflammatory response leads to a large accumulation of ROS, which exceeds the physiological antioxidant capacity, impeding cell migration and proliferation and thus preventing tissue remodelling. It has been shown that antioxidants can accelerate wound healing, especially for chronic wounds. In this study, we developed a hydrogel based on a natural polymer and modified with selenium to add antioxidant and antimicrobial properties. The synthesis reaction has been confirmed with NMR and atomic absorption spectroscopy. The mechanical properties of the hydrogel were characterized by rheological tests. Viability assays were performed with human dermal fibroblasts. Hence, we developed an antioxidant and antimicrobial hydrogel with good biocompatible properties, which seems to be a promising therapy for the treatment of chronic wounds.