Inter-and intramolecular adhesion mechanisms of mussel foot proteins

Mussel foot proteins(Mfps) secreted in the byssal plaque of marine mussels are widely researched for their relevance to mussel adhesion in water. As the abundant residue in the amino acid sequences of major adhesive proteins, 3,4-dihydroxyphenylalanine(Dopa) or its catecholic moiety plays a key role in both Mfp binding to surface and cohesive cross-linking of Mfps in byssal plaques. The binding performance of an Mfp significantly depends on the content and redox state of Dopa, whereas the types of interaction vary in line with different surface chemistries and p H conditions. Thorough understanding of mussel adhesion from a molecular perspective is crucial to promote the application of synthetic mussel-bionic adhesives. This article presents a brief review of the research progress on the adhesion mechanisms of Mfps, which further emphasizes the contributions of Dopamediated interactions and considers other amino acids and factors. The involved inter-and intramolecular interactions are responsible for not only the diverse adhesion capacities of an adhesive byssal plaque as mussel's adhesion precursor but also the formation and properties of the plaque structure.

The Adhesion and Formation Mechanism of Blast Furnace Gunning Layer

Basing on the study of the equilibrium relationship of interfacial tension among gunning particles, repaired surface and atmosphere, this test is in a position to draw a conclusion concerning the adhesion mechanism of the grinning refractory and the repaired surface, which illustrates the formation of the bottom gunning layer by moist fine gunning particles on the repaired surface. Also involved within the scope of discussion and probe are the patterns formed under this contacting effect and the formation mechanism of gunning layer. The analytic research regarding the behavior of gunning interface has ascribed the influence upon adhesion intensity to the quality of furnace gunning refractory, the state of the repaired surface and the gunning techniques.

A Boron-based Adhesion Aid for Efficient Bonding of Silicone Rubber and Epoxy Resin

We improved the adhesion between silicon based insulating materials and epoxy resin composites by adding the adhesion promoter cycloborosiloxane(BSi,cyclo-1,3,3,5,7,7-hexaphenyl-1,5-diboro-3,7-disiloxane).The experimental results show that the addition of BSi in the silicone rubber(SR)system significantly increases the tensile shear strength between BSi and epoxy resin(EP),reaching 309%of the original value.On this basis,the mechanism of BSi to enhance the adhesion effect was discussed.The electron deficient B in BSi attracted the electron rich N and O in EP to enhance the chemical interaction,combined with the interfacial migration behavior in the curing process,to improve the adhesion strength.This study provides the design and synthesis ideas of adhesive aids,and a reference for further exploring the interface mechanism of epoxy resin matrix composites.

An efficient method for enhancing adhesion and uniformity of Al_(2)O_(3) coatings on nickel micro-foam used in micropacked beds

Methods of coating Al_(2)O_(3) on nickel micro-foam were compared and screened,aiming to overcome the capillary force and prepare the micro-foam monolithic catalyst coatings.The surface of micro-foam substrate was pretreated by a chemical etching method to improve the adhesion of the coatings on the substrate.The results showed that the slurry circulation at 162 ml·min^(-1) was evaluated as the optimal method.The pore size on the substrate surface can be controlled by changing the pretreatment conditions.An empirical correlation was also proposed,showing an excellent practicality for predicting the pore size.The adhesion of the coatings with substrate pretreatment was significantly better than that without substrate pretreatment.The minimum value of mass loss after ultrasonic vibration was 3.9%.This mainly attributes to the squeezing of Al_(2)O_(3) particles in the pores of substrate surface.The coatings on nickel micro-foam are hopefully used in micropacked beds for catalytic reactions.

Probing the mechanosensitivity in cell adhesion and migration: Experiments and modeling

Cell adhesion and migration are basic physiolog- ical processes in living organisms. Cells can actively probe their mechanical micro-environment and respond to the ex- ternal stimuli through cell adhesion. Cells need to move to the targeting place to perform function via cell migration. For adherent cells, cell migration is mediated by cell-matrix adhesion and cell-cell adhesion. Experimental approaches, especially at early stage of investigation, are indispensable to studies of cell mechanics when even qualitative behaviors of cell as well as fundamental factors in cell behaviors are unclear. Currently, there is increasingly accumulation of ex- perimental data of measurement, thus a quantitative formula- tion of cell behaviors and the relationship among these fun- damental factors are highly needed. This quantitative under- standing should be crucial to tissue engineering and biomed- ical engineering when people want to accurately regulate or control cell behaviors from single cell level to tissue level. In this review, we will elaborate recent advances in the ex- perimental and theoretical studies on cell adhesion and mi- gration, with particular focuses laid on recent advances in experimental techniques and theoretical modeling, through which challenging problems in the cell mechanics are sug- gested.

Research progress and application prospect of functional adhesive materials in the field of oil and gas drilling and production

By summarizing the composition,classification,and performance characterization of functional adhesive materials,the adhesion mechanisms of functional adhesive materials,such as adsorption/surface reaction,diffusion,mechanical interlocking,and electrostatic adsorption,are expounded.The research status of these materials in oil and gas drilling and production engineering field such as lost circulation prevention/control,wellbore stabilization,hydraulic fracturing,and profile control and water plugging,and their application challenges and prospects in oil and gas drilling and production are introduced comprehensively.According to the applications of functional adhesive materials in the field of oil and gas drilling and production at this stage,the key research directions of functional adhesive materials in the area of oil and gas drilling and production are proposed:(1)blending and modifying thermoplastic resins or designing curable thermoplastic resins to improve the bonding performance and pressure bearing capacity of adhesive lost circulation materials;(2)introducing low-cost adhesive groups and positive charge structures into polymers to reduce the cost of wellbore strengthening agents and improve their adhesion performance on the wellbore;(3)introducing thermally reversible covalent bond into thermosetting resin to prevent backflow of proppant and improve the compressive strength of adhesive proppant;(4)introducing thermally reversible covalent bonds into thermoplastic polymers to improve the temperature resistance,salt-resistance and water shutoff performance of adhesive water shutoff agents.

Adhesive hydrogels for bioelectronics

Benefiting from the unique advantages of superior biocompatibility,strong stability,good biodegradability,and adjustable mechanical properties,hydrogels have attracted extensive research interests in bioelectronics.However,due to the existence of an interface between hydrogels and human tissues,the transmission of electrical signals from the human tissues to the hydrogel electronic devices will be hindered.The adhesive hydrogels with adhesive properties can tightly combine with the human tissue,which can enhance the contact between the electronic devices and human tissues and reduce the contact resistance,thereby improving the performance of hydrogel electronic devices.In this review,we will discuss in detail the adhesion mechanism of adhesive hydrogels and elaborate on the design principles of adhesive hydrogels.After that,we will introduce some methods of performance evaluation for adhesive hydrogels.Finally,we will provide a perspective on the development of adhesive hydrogel bioelectronics.

Mechanisms Underlying the Biological WetAdhesion:Coupled Effects of Interstitial Liquid and Contact Geometry

Wet adhesion is widely adopted in biological adhesion systems in nature,and it is beneficial to design new materials with desired properties based on the underlying physics of wet adhesion.The aim of this work is to develop a design criterion to regulate the wet adhesion.The effects of different contact shapes(flat and sphere)and morphologies of the substrate(smooth,microstructure and nanostructure)on the adhesion force are investigated.Combining with the theoretical models,the dominated factors in the separation process and isolating the viscous contributions from the capillary interactions are evaluated.The results demonstrate that the adhesion mechanisms depend significantly on the capillary numbers of the interstitial liquid and the contact geometry,and the ratio of capillary force to viscous force is a key to regulate the wet adhesion mechanism.These findings can not only explain some phenomena of wet adhesion to organisms,but also provide some inspirations to design new adhesion technology for robotic fingers that can grasp objects in wet environments.

Applying Thermal Spraying to Forming Glass Enamel Coatings

Applying thermal spraying to forming glass enamel coatings is explored in present paper. Four kinds of glass enamel frits suited to flame spraying have been prepared and the flame spraying experiments have conducted. It is possible to form glass enamel coatings on still substrates by a proper flame spraying technique. Besides the obvious mechanical adhesion obtained by roughening the surface of the still substrates, the element micro diffusion between glass enamel coatings and substrates have been produced during the spraying process, Hence metallurgical chemical adhesion is derived.

Bridging wounds:tissue adhesives’essential mechanisms,synthesis and characterization,bioinspired adhesives and future perspectives

Bioadhesives act as a bridge in wound closure by forming an effective interface to protect against liquid and gas leakage and aid the stoppage of bleeding.To their credit,tissue adhesives have made an indelible impact on almost all wound-related surgeries.Their unique properties include minimal damage to tissues,low chance of infection,ease of use and short wound-closure time.In contrast,classic closures,like suturing and stapling,exhibit potential additional complications with long operation times and undesirable inflammatory responses.Although tremendous progress has been made in the development of tissue adhesives,they are not yet ideal.Therefore,highlighting and summarizing existing adhesive designs and synthesis,and comparing the different products will contribute to future development.This review first provides a summary of current commercial traditional tissue adhesives.Then,based on adhesion interaction mechanisms,the tissue adhesives are categorized into three main types:adhesive patches that bind molecularly with tissue,tissuestitching adhesives based on pre-polymer or precursor solutions,and bioinspired or biomimetic tissue adhesives.Their specific adhesion mechanisms,properties and related applications are discussed.The adhesion mechanisms of commercial traditional adhesives as well as their limitations and shortcomings are also reviewed.Finally,we also discuss the future perspectives of tissue adhesives.

Modeling nanoscale ice adhesion

Anti-icing is crucial for numerous instruments and devices in low temperature circum- stance. One of the approaches in anti-icing is to reduce ice adhesion strength, seeking spontaneous de-icing processes by natural forces of gravity or by winds. In order to enable tai- lored surface icephobicity design, research requires a good theoretical understanding of the atomistic interacting mechanisms between water/ice molecules and their adhering substrates. Herein, this work focuses on using atomistic modeling and molecular dynamics simulation to build a nanosized ice-cube adhering onto silicon surface, with different contact modes of solid-solid and solid-liquid-solid patterns. This study provides atomistic models for probing nanoscale ice adhesion mechanics and theoretical platforms for explaining experimental results.

A biomimetic robot crawling bidirectionally with load inspired by rock-climbing fish

Using a unique adhesive locomotion system,the rock-climbing fish(Beaufortia kweichowensis)adheres to submerged surfaces and crawls both forwards and backwards in torrential streams.To emulate this mechanism,we present a biomimetic robot inspired by the locomotion model of the rock-climbing fish.The prototype contains two anisotropic adhesive components with linkages connected to a linear actuator.Each anisotropic adhesive component consists of one commercial sucker and two retractable bioinspired fin components.The fin components mimic the abduction and adduction of pectoral and pelvic fins through the retractable part to move up and down.The robot prototype was tested on vertical and inverted surfaces,and worked successfully.These results demonstrate that this novel system represents a new locomotion solution for surface movement without detachment from the substrate.

Mechanically robust antireflective coatings

Mechanical strength is an essential parameter that influences and limits the lifetime performance of antireflective （AR） coatings in optical devices. Speciflcally, amphiphobic AR coatings with reduced reflectance are of great significance as they considerably enlarge the range of fundamental applications. Herein, we describe the design and fabrication of amphiphobic AR coatings with reduced reflectance and enhanced mechanical resilience. Introducing a thin polytetrafluoroethylene （PTFE） layer on top of the bilayer SiOz coating via vapor deposition method makes it highly liquid repellent. We achieved reduced reflectance （〈 1%） over the entire visible wavelength range, as well as tunability according to the desired wavelength region. The fabricated film showed better thermal stability （up to 300℃） with stable AR efficiency, when an ultrathin dense coat of Al2O3 was deposited via atomic layer deposition （ALD） on the polymer-based bilayer SiO2 antireflective coating （P-BSAR）. The experimental results prove that the omnidirectional AR coating in this study exhibits multifunctional properties and should be suitable for the production of protective optical equipment and biocompatible polymer films for the displays of portable electronic devices.