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The suction cups found in octopus tentacles are the inspiration for a synthetic adhesive that functions well in dry and wet conditions and is resistant to chemical contamination. Octopus-inspired sticky patch Adhesives fall broadly into two categories, working either through chemical bonding or attraction at the interface, or through mechanical interlocking to ensure that surfaces stick together. Finding an adhesive in either of these categories that works under dry conditions and when immersed in liquids, and isn't readily contaminated, is an ongoing challenge. Changhyun Pang and colleagues have taken inspiration from the shape of octopus suckers to develop and fabricate a textured polymer patch that adheres through mechanical deformation. The patch displays good adhesive properties in various media, yet is resistant to chemical contamination. Adhesion strategies that rely on mechanical interlocking or molecular attractions between surfaces can suffer when coming into contact with liquids 1 , 2 . Thus far, artificial wet and dry adhesives have included hierarchical mushroom-shaped or porous structures that allow suction or capillarity 3 , 4 , 5 , 6 , supramolecular structures comprising nanoparticles 7 , and chemistry-based attractants that use various protein polyelectrolytes 8 , 9 , 10 . However, it is challenging to develop adhesives that are simple to make and also perform well—and repeatedly—under both wet and dry conditions, while avoiding non-chemical contamination on the adhered surfaces 11 . Here we present an artificial, biologically inspired, reversible wet/dry adhesion system that is based on the dome-like protuberances found in the suction cups of octopi. To mimic the architecture of these protuberances 12 , 13 , 14 , we use a simple, solution-based, air-trap technique that involves fabricating a patterned structure as a polymeric master, and using it to produce a reversed architecture, without any sophisticated chemical syntheses or surface modifications. The micrometre-scale domes in our artificial adhesive enhance the suction stress. This octopus-inspired system exhibits strong, reversible, highly repeatable adhesion to silicon wafers, glass, and rough skin surfaces under various conditions (dry, moist, under water and under oil). To demonstrate a potential application, we also used our adhesive to transport a large silicon wafer in air and under water without any resulting surface contamination.

In this paper, a Ni-P-SiC composite coating was prepared on the surface of AZ91D alloy by optimizing the process, with the goal of improving the corrosion resistance of magnesium alloys. The micromorphology, microstructure, and bonding status of the Ni-P-SiC composite coating on the surface of AZ91D alloy were analyzed and evaluated using a scanning electron microscope, X-ray diffraction (XRD), and a coating adhesion automatic scratch tester. The macro surface of the Ni-P-Si composite coating is flat and gray, with large roughness. The micro surface is composed of continuously arranged cellular protuberances, with SiC microparticles dispersed across the protuberances. The composite coating has a structure dominated by an amorphous phase, mixed with a micro-crystalline phase. With the extension of plating time, the critical time for the Ni-P-SiC composite coating to peel off from the magnesium alloy matrix increases. The Ni-P-SiC composite coating with 120min plating time has better quality.

The seeds of many species in the order Caryophyllales exhibit surface protuberances called tubercles. While tubercle shape and distribution have often been proposed as taxonomic criteria, paradoxically, their description has primarily relied on adjectives, with quantitative data on tubercle width, height, and other measurements lacking in the literature. Recently, a quantitative analysis of seed surface tubercles based on tubercle width, height, and curvature values (maximum and average curvature, and maximum to average curvature ratio) was proposed and applied to individual populations of a total of 31 species, with 12 belonging to Silene subg. Behenantha and 19 to S. subg. Silene. Tubercles were classified into two categories: echinate and rugose. Echinate tubercles exhibited higher values of height and curvature, and lower width, and were more prevalent in species of S. subg. Behenantha, while the rugose type was more abundant in S. subg. Silene. This work explored infraspecific differences in tubercle size and shape. For this, measurements of tubercle width, height and curvature were applied to 31 populations of eight species of Silene. Significant differences between populations were observed for most of the species examined. A particular tubercle type, previously described as umbonate or mammillate, was identified in S. nocturna seeds, characterized by high curvature values.

The performance of vertical axis wind turbine (VAWT) is mainly affected by the dynamic stall process of the blade. Inspired by the anti-stall performance of the humpback whale flipper, leading edge protuberances (LEPs) are applied to 2-blade VAWT. Based on computational fluid dynamics simulation method, the effects of LEPs amplitude on VAWT performance are investigated when blade tip speed ratio is 2.19. The results show that the larger the amplitude of the LEP, the lower the average power coefficient. When the number of protuberances is 3, the average power coefficient of the VAWT with a protuberance amplitude of 6.625mm is 1.8% higher than prototype blade. Considering the impact of increasing the chord length of biomimetic blades, the average tangential force coefficient of all biomimetic VAWTs decreases. The peak section performance of the bionic blade decreases significantly while the trough section performance increases significantly. The difference between the peak section and trough section of the LEPS plays an important role in improving the performance. This study provides a reference for the application of bionic protuberances in VAWTs.

Abstract Sanguina nivaloides is the main alga forming red snowfields in high mountains and Polar Regions. It is non-cultivable. Analysis of environmental samples by X-ray tomography, focused-ion-beam scanning-electron-microscopy, physicochemical and physiological characterization reveal adaptive traits accounting for algal capacity to reside in snow. Cysts populate liquid water at the periphery of ice, are photosynthetically active, can survive for months, and are sensitive to freezing. They harbor a wrinkled plasma membrane expanding the interface with environment. Ionomic analysis supports a cell efflux of K + , and assimilation of phosphorus. Glycerolipidomic analysis confirms a phosphate limitation. The chloroplast contains thylakoids oriented in all directions, fixes carbon in a central pyrenoid and produces starch in peripheral protuberances. Analysis of cells kept in the dark shows that starch is a short-term carbon storage. The biogenesis of cytosolic droplets shows that they are loaded with triacylglycerol and carotenoids for long-term carbon storage and protection against oxidative stress.

Human mitochondrial ribosomes are highly divergent from all other known ribosomes and are specialized to exclusively translate membrane proteins. They are linked with hereditary mitochondrial diseases and are often the unintended targets of various clinically useful antibiotics. Using single-particle cryogenic electron microscopy, we have determined the structure of its large subunit to 3.4 angstrom resolution, revealing 48 proteins, 21 of which are specific to mitochondria. The structure unveils an adaptation of the exit tunnel for hydrophobic nascent peptides, extensive remodeling of the central protuberance, including recruitment of mitochondrial valine transfer RNA (tRNAVal) to play an integral structural role, and changes in the tRNA binding sites related to the unusual characteristics of mitochondrial tRNAs.

Salmonella utilizes a type 3 secretion system to translocate virulence proteins (effectors) into host cells during infection 1 . The effectors modulate host cell machinery to drive uptake of the bacteria into vacuoles, where they can establish an intracellular replicative niche. A remarkable feature of Salmonella invasion is the formation of actin-rich protuberances (ruffles) on the host cell surface that contribute to bacterial uptake. However, the membrane source for ruffle formation and how these bacteria regulate membrane mobilization within host cells remains unclear. Here, we show that Salmonella exploits membrane reservoirs for the generation of invasion ruffles. The reservoirs are pre-existing tubular compartments associated with the plasma membrane (PM) and are formed through the activity of RAB10 GTPase. Under normal growth conditions, membrane reservoirs contribute to PM homeostasis and are preloaded with the exocyst subunit EXOC2. During Salmonella invasion, the bacterial effectors SipC, SopE2, and SopB recruit exocyst subunits from membrane reservoirs and other cellular compartments, thereby allowing exocyst complex assembly and membrane delivery required for bacterial uptake. Our findings reveal an important role for RAB10 in the establishment of membrane reservoirs and the mechanisms by which Salmonella can exploit these compartments during host cell invasion. The plasma membrane of eukaryotic cells can fold inwards to create reservoirs that store or release excess membrane. Zhu et al. show that Salmonella -secreted effectors modulate these reservoirs to facilitate host cell invasion.

The wavy leading edge (WLE, also known as leading edge protuberances) is a passive flow control device inspired by the humpback whale pectoral flippers. It reduces the flow of three-dimensional effects on wings and increases their aerodynamic performance at high angles of attack. Despite the numerous studies on its aerodynamic benefits, research on its possible applications is still incipient. Therefore, this article addresses an evaluation of the WLE effects on the aerodynamic performance of a winglet. A rectangular wing, a base smooth leading edge winglet, and a winglet with WLE were designed and manufactured for CFD simulations and wind tunnel measurements. The winglet with WLE increased the maximum aerodynamic efficiency, i.e. this configuration reduced the induced drag by increasing wingtip vortex dissipation at a given angle-of-attack. Such results were used in re-evaluations of the aerodynamic performance of an original agricultural aircraft initially configured with a multi-winglet device. The winglet with WLE showed to be effective at increasing the aircraft operational time and range under a simulated actual condition.

Leading-edge protuberances (LEPs) suppress flow separation and improve the aerodynamic performance of fluid machinery. In this paper, bionic protuberance was added to the leading edge of the wind turbine blade. Three parameters were designed to control the protuberance shape (amplitude, attenuation, and number), and a comparative study was conducted using computational fluid dynamics. Results indicate that the bionic LEPs can influence the flow pattern. Under the rated condition with the wind speed of 11.4 m/s, using the LEPs with a larger attenuation can increase the output power of the wind turbine by 1.36 %. Research on the parameters of the LEP shows that when using LEPs with faster attenuation rate and fewer number, the vortex on the suction surface can be reduced, which brings positive gains. Unsteady characteristics indicate that LEPs can reduce the blade fluctuations during operation and can improve the operational stability. Therefore, bionic LEPs can effectively enhance the performance of wind turbines.

The aerodynamic performance of compressor blades is highly sensitive to variations in streamwise curvature near the leading edge. Inadequate curvature may lead to the formation of separation bubbles or even stall, posing challenges to the blade profile design. Inspired by the spanwise tubercles on humpback whale flippers, this study proposes the implementation of streamwise curvature-based bionic protuberances near the leading edge of the NASA Stator 37 blade profile, which aims to mitigate flow separation while preserving a smooth global profile curvature. The methodology involves first optimizing the global curvature distribution of the blade profile using Bezier curves, followed by localized curvature amplification at the junction of the leading edge and the blade profile to construct bionic protuberances. A systematic numerical investigation is conducted to evaluate the impact of the curvature amplification ratio on aerodynamic performance. Results indicate that appropriate curvature amplification effectively extends the stable operating range and improves performance at moderate and high incidence angles. Specifically, a curvature amplification ratio of 103 increases the stable operating range by 23.4%; at an incidence angle of 6°, a ratio of 82.4 significantly mitigates the adverse pressure gradient at the leading edge, reducing the total pressure loss coefficient by 57.8%; and at 10° (near-stall condition), a ratio of 136.9 effectively suppresses flow separation, reducing the trailing-edge boundary layer thickness by 53.6%.