Skin and dry adhesion

2018 ◽  
Author(s):  
Changhyun Pang ◽  
Chanseok Lee ◽  
Hoon Eui Jeong ◽  
Kahp-Yang Suh
Keyword(s):  
Material Properties ◽  
Structural Features ◽  
Mechanical Interlocking ◽  
Multi Scale ◽  
Skin Patch ◽  
Reversible Adhesion ◽  
Dry Adhesion ◽  
Close Observation ◽  
Dry Adhesives ◽  
Shed Light

Close observation of various attachment systems in animal skins has revealed various exquisite multi-scale architectures for essential functions such as locomotion, crawling, mating, and protection from predators. Some of these adhesion systems of geckos and beetles have unique structural features (e.g. high-aspect ratio, tilted angle, and hierarchical nanostructure), resulting in mechanical interlocking mediated by van der Waals forces or liquid secretion (capillary force). In this chapter, we present an overview of recent advances in bio-inspired, artificial dry adhesives, and biomimetics in the context of nanofabrication and material properties. In addition, relevant bio-inspired structural materials, devices (clean transportation device, interlocker, biomedical skin patch, and flexible strain-gauge sensor) and microrobots are briefly introduced, which would shed light on future smart, directional, and reversible adhesion systems.

scholarly journals Harnessing reversible dry adhesion using shape memory polymer microparticles

RSC Advances ◽  
2021 ◽  
Vol 11 (32) ◽  
pp. 19616-19622
Author(s):  
Wenbing Li ◽  
Junhao Liu ◽  
Wanting Wei ◽  
Kun Qian
Keyword(s):  
Shape Memory ◽  
Shape Memory Polymer ◽  
Shape Memory Polymers ◽  
Memory Effects ◽  
Reversible Adhesion ◽  
Dry Adhesion ◽  
Bonding Property ◽  
Shape Memory Effects ◽  
Polymer Microparticles

Shape memory polymers can provide excellent bonding property because of their shape memory effects. This paper proposes an adhesive unit that is capable of repeatable smart adhesion and exhibits reversible adhesion under heating.

scholarly journals Rectangle-capped and tilted micropillar array for enhanced anisotropic anti-shearing in biomimetic adhesion

2015 ◽  
Vol 12 (106) ◽  
pp. 20150090 ◽  
Author(s):  
Yue Wang ◽  
Xiangming Li ◽  
Hongmiao Tian ◽  
Hong Hu ◽  
Yu Tian ◽  
...  
Keyword(s):  
Rough Surfaces ◽  
Moulding Process ◽  
Practical Applications ◽  
Dry Adhesion ◽  
Dry Adhesives ◽  
Shearing Strength ◽  
Self Cleaning ◽  
Reverse Shearing ◽  
Orthogonal Anisotropy ◽  
Micropillar Array

Dry adhesion observed in the feet of various small creatures has attracted considerable attention owing to the unique advantages such as self-cleaning, adaptability to rough surfaces along with repeatable and reversible adhesiveness. Among these advantages, for practical applications, proper detachability is critical for dry adhesives with artificial microstructures. In this study, we present a microstructured array consisting of both asymmetric rectangle-capped tip and tilted shafts, which produce an orthogonal anisotropy of the shearing strength along the long and short dimensions of the tip, with a maximum anti-shearing in the two directions along the longer dimension. Meanwhile, the tilt feature can enhance anisotropic shearing adhesion by increasing shearing strength in the forward shearing direction and decreasing strength in the reverse shearing direction along the short dimension of the tip, leading to a minimum anti-shearing in only one of the two directions along the shorter dimension of the rectangular tip. Such a microstructured adhesive with only one weak shearing direction, leading to well-controlled attachment and detachment of the adhesive, is created in our experiment by conventional double-sided exposure of a photoresist followed by a moulding process.

Neutrophil extracellular traps in feline cardiogenic arterial thrombi: a pilot study

2021 ◽  
pp. 1098612X2110449
Author(s):  
Ronald HL Li ◽  
Nghi Nguyen ◽  
Joshua A Stern ◽  
Laetitia M Duler
Keyword(s):  
Random Fields ◽  
Histone H3 ◽  
Neutrophil Extracellular Traps ◽  
Structural Features ◽  
Proximal Region ◽  
Aortic Bifurcation ◽  
Iliac Arteries ◽  
Descending Aorta ◽  
Extracellular Traps ◽  
Shed Light

Objectives The aim of this study was to investigate the spatial distribution of neutrophil extracellular traps (NETs) in cardiogenic arterial thromboembolism (CATE). Specifically, we aimed to examine the related structural features of NETs in feline arterial thrombi in relation to their arterial locations. Methods Paraffin-embedded aortic bifurcations from nine cats with hypertrophic cardiomyopathy (four with CATE and five without) were deparaffinized, and NETs were identified by immunodetection based on colocalization of cell-free DNA, citrullinated histone H3 and neutrophil elastase. The distribution of NETs in thrombi within the aortic bifurcations and common iliac arteries (CIAs) was compared based on their proximity to the descending aorta (proximal, mid, distal). Ten random fields per section were captured at × 10 and × 20 magnification for each section of the clot and analyzed. Results The distributions of NETs in thrombi within the aortic bifurcation and CIAs were found to differ in relation to their assigned zones (proximal, mid, distal; P = 0.04); NETs were concentrated mostly in the proximal region in the aortic bifurcations (47.56%, interquartile range [IQR] 14.07–77.95) and CIAs (44.69%, IQR 24.65–85.28), compared with the distal regions (2.69%, IQR 0.10–50.04 [P = 0.027]; 7.08%, IQR 1.27–59.33 [P = 0.02]). Conclusions and relevance The variation in NET distribution within arterial thrombi may shed light on the pathogenesis of thrombus growth. This may be due to possible neutrophil entrapment or variations in shear stress.

GRAVIMETRIC SURVEY AND GRAVIMETRIC DATABASE IN UKRAIN “Dniprogeofizika” during 2000–2011 carried out works on collection, analysis and formation of an electronic gravimetric data base (GDB) of the territory of Ukraine. Based on the results of the work carried out, a systematization of the materials of all conditional gravimetric surveys in scales of 1:200000 – 1:1000 was carried out. The database was created for the purpose of systematization, reliable storage and operative application of digital attributes of gravimetric surveys of the last years with a possibility of construction of gravimetric maps of various territories and scales. Information from the database makes it possible to study both the general structure of individual tectonic structures, and to perform detailing to obtain additional information about the structural features of each element. As an example, materials on the study of the engineering and geological conditions of the southern industrial zone of Kryvbas are given. The use of the GDB allows to correctly supplement the picture of the gravitational field obtained from individual profiles when constructing multi-scale spatial maps and to reflect more detail the structural features of the upper part of the earth’s crust.GRAVIMETRIC SURVEY AND GRAVIMETRIC DATABASE IN UKRAIN

2021 ◽  
Author(s):  
V. Svistun ◽  
P. Pigulevskiy
Keyword(s):  
General Structure ◽  
Structural Features ◽  
Industrial Zone ◽  
Tectonic Structures ◽  
Gravimetric Survey ◽  
Additional Information ◽  
Multi Scale ◽  
Geological Conditions ◽  
Gravimetric Data ◽  
Individual Profiles

A multi-scale E-Jet 3D printing regulated by structured multi-physics field

2021 ◽  
Author(s):  
Kai Li ◽  
Yihui Zhao ◽  
Maiqi Liu ◽  
Xiaoying Wang ◽  
Fangyuan Zhang ◽  
...  
Keyword(s):  
Tissue Engineering ◽  
3D Printing ◽  
Aspect Ratio ◽  
Process Parameters ◽  
High Aspect Ratio ◽  
Thermal Field ◽  
Structural Features ◽  
Microfluidic Chips ◽  
Multi Scale ◽  
Fluid Field

Abstract Micro/nano scale structure as important functional part have been widely used in wearable flexible sensors, gas sensors, biological tissue engineering, microfluidic chips super capacitors and so on. Here a multi-scale electrohydrodynamic jet (E-Jet) 3D printing approach regulated by structured multi-physics fields was demonstrated to generate 800 nm scale 2D geometries and high aspect ratio 3D structures. The simulation model of jetting process under resultant effect of top fluid field, middle electric field and bottom thermal field was established. And the physical mechanism and scale law of jet formation were studied. The effects of thermal field temperature, applied voltage and flow rate on the jet behaviors were studied; and the range of process parameters of stable jet was obtained. The regulation of printing parameters was used to manufacture the high resolution gradient graphics and the high aspect ratio structure with tight interlayer bonding. The structural features could be flexibly adjusted by reasonably matching the process parameters. Finally, PCL/PVP composite scaffolds with cell-scale fiber and ordered fiber spacing were printed. The proposed E-Jet printing method provides an alternative approach for the application of biopolymer materials in tissue engineering.

scholarly journals The final steps of [FeFe]-hydrogenase maturation

2019 ◽  
Vol 116 (32) ◽  
pp. 15802-15810 ◽  
Author(s):  
Oliver Lampret ◽  
Julian Esselborn ◽  
Rieke Haas ◽  
Andreas Rutz ◽  
Rosalind L. Booth ◽  
...  
Keyword(s):  
Functional Integration ◽  
Structural Features ◽  
Site Directed Mutagenesis ◽  
Structural Reorganization ◽  
Biologically Inspired ◽  
Hydrogenase Maturation ◽  
Flexible Loop ◽  
Loop Region ◽  
Shed Light ◽  
Secondary Ligand

The active site (H-cluster) of [FeFe]-hydrogenases is a blueprint for the design of a biologically inspired H2-producing catalyst. The maturation process describes the preassembly and uptake of the unique [2FeH] cluster into apo-hydrogenase, which is to date not fully understood. In this study, we targeted individual amino acids by site-directed mutagenesis in the [FeFe]-hydrogenase CpI of Clostridium pasteurianum to reveal the final steps of H-cluster maturation occurring within apo-hydrogenase. We identified putative key positions for cofactor uptake and the subsequent structural reorganization that stabilizes the [2FeH] cofactor in its functional coordination sphere. Our results suggest that functional integration of the negatively charged [2FeH] precursor requires the positive charges and individual structural features of the 2 basic residues of arginine 449 and lysine 358, which mark the entrance and terminus of the maturation channel, respectively. The results obtained for 5 glycine-to-histidine exchange variants within a flexible loop region provide compelling evidence that the glycine residues function as hinge positions in the refolding process, which closes the secondary ligand sphere of the [2FeH] cofactor and the maturation channel. The conserved structural motifs investigated here shed light on the interplay between the secondary ligand sphere and catalytic cofactor.

A New Sampling Approach for the Multi-Scale Design of Metallic Materials

2020 ◽  
Vol 142 (8) ◽  
Author(s):  
Pinar Acar
Keyword(s):  
Material Properties ◽  
Sampling Method ◽  
Solution Space ◽  
Computational Time ◽  
Polycrystalline Materials ◽  
Microstructure Design ◽  
Multi Scale ◽  
Generate Property ◽  
Scale Design ◽  
Sampling Approach

Abstract We present a new sampling method for the multi-scale design of polycrystalline materials, which improves the computational time efficiency compared to the existing computational approaches. The solution strategy aims to find microstructure designs that optimize component-scale mechanical properties. The microstructure is represented with a probabilistic texture descriptor that quantifies the volume fractions of different crystallographic orientations. However, the original microstructure design space is high-dimensional and thus optimization in this domain is not favorable. Instead, we generate property closures, which are the reduced spaces of volume-averaged material properties that are computed in terms of the microstructural texture descriptors. We observe that the traditional design approaches which are based on sampling in the original microstructure space and sampling on the property closure are inefficient as they lead to highly concentrated design samples in the solution space. Therefore, we introduce a new sampling method in the property closure, which creates simplexes using the triangulation of the property hull and then generating samples for each simplex. Example problems include the optimization of Galfenol and α-titanium microstructures to improve non-linear material properties. The new sampling approach is shown to obtain better solutions while decreasing the required computational time compared to the previous microstructure design methods.

scholarly journals Atg8-Family Proteins—Structural Features and Molecular Interactions in Autophagy and Beyond

Cells ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 2008 ◽  
Author(s):  
Nicole Wesch ◽  
Vladimir Kirkin ◽  
Vladimir V. Rogov
Keyword(s):  
Protein Interactions ◽  
Membrane Trafficking ◽  
Structural Features ◽  
Structural Level ◽  
Interacting Proteins ◽  
Therapeutic Approaches ◽  
Basic Principles ◽  
Interaction Partners ◽  
Shed Light

Autophagy is a common name for a number of catabolic processes, which keep the cellular homeostasis by removing damaged and dysfunctional intracellular components. Impairment or misbalance of autophagy can lead to various diseases, such as neurodegeneration, infection diseases, and cancer. A central axis of autophagy is formed along the interactions of autophagy modifiers (Atg8-family proteins) with a variety of their cellular counter partners. Besides autophagy, Atg8-proteins participate in many other pathways, among which membrane trafficking and neuronal signaling are the most known. Despite the fact that autophagy modifiers are well-studied, as the small globular proteins show similarity to ubiquitin on a structural level, the mechanism of their interactions are still not completely understood. A thorough analysis and classification of all known mechanisms of Atg8-protein interactions could shed light on their functioning and connect the pathways involving Atg8-proteins. In this review, we present our views of the key features of the Atg8-proteins and describe the basic principles of their recognition and binding by interaction partners. We discuss affinity and selectivity of their interactions as well as provide perspectives for discovery of new Atg8-interacting proteins and therapeutic approaches to tackle major human diseases.

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