adhesion

摘要： The mechanisms that regulate neural stem cell(NSC)lineage progression and maintain NSCs within diffe rent domains of the adult neural stem cell niche,the subventricular zone are not well defined.Quiescent NSCs are arranged at the apical ventricular wall,while mitotically activated NSCs are found in the basal,vascular region of the subventricular zone.Here,we found that ADAM 10(a disintegrin and metalloproteinase 10)is essential in NSC association with the ventricular wall,and via this adhesion to the apical domain,ADAM10 regulates the switch from quiescent and undiffe rentiated NSC to an actively prolife rative and differentiating cell state.Processing of JAMC(junctional adhesion molecule C)by ADAM 10 increases Rap1 GAP activity.This molecular machinery promotes NSC transit from the apical to the basal compartment and subsequent lineage progression.Understanding the molecular mechanisms responsible for regulating the proper positioning of NSCs within the subventricular zone niche and lineage progression of NSCs could provide new targets for drug development to enhance the regenerative prope rties of neural tissue.

摘要： In this study, a point source mathematical model is proposed to describe the diffusion of adenosine di-phosphate (ADP) from either damaged red blood cell (RBC) or activated platelet. The convective diffusion equation is reduced to describe the suggested problem. The final differential equation is solved using Laplace transforms and ADP concentration profiles around the source are obtained. Thrombi of 5 to 20 μm3 containing platelets and a range of red blood cells (RBCs) (0%, 25%, 50%, 75%, 100%) concentrations are used to apply the model. Reported ADP concentrations in the literature are used and its dynamic release from the point source is calculated. Results suggest that RBC chemical contribution to platelet aggregation in the bulk is much less than that of platelet (almost) negligible. However, the physical effect of RBCs is dominant in the bulk through augmentation of released ADP and platelets diffusivities. Moreover, the chemical contribution reported in previous studies is suggested to be as a result of interaction of RBC with the surface under the influence of shear stresses in the boundary region.

摘要： The characterization of micro-surface mechanical and electrical properties of the natural rock materials remains inadequate,and their macroscopic performance can be better comprehended by investigating the surface properties.With this purpose,the present research focuses on characterizing the microsurface morphology,Derjaguin-Muller-Toporov(DMT)modulus,adhesion,and potential of granite,shale,and limestone by employing the atomic force microscope(AFM)as a pioneer attempt.The results show that the micro-surface morphology of the rock fluctuates within hundreds of nanometers,among which the granite micro-surface is comparatively the smoothest,followed by limestone.The morphology of the shale is the roughest,indicating that the regional difference of shale micro-surface is dominant.The distribution of the adhesion on rock micro-surface is uneven;the average adhesion of eight measuring areas for shale is 23.93 n N,accounting for three times of granite and limestone,while the surface DMT modulus of shale is relatively lower than granite and limestone.It is inferred from the obtained results that higher surface adhesion is helpful to the gas adsorption of shale,and the lower surface DMT(elastic)modulus is useful to the formation of fractures and pores.Thus,these two are the micromechanical basis of shale gas adsorption.Additionally,introducing a method to reduce the surface adhesion will benefit the exploration of unconventional resources such as shale gas.The micro-surface of the three types of rocks all shows electricity,with average potential ranging from tens of millivolts to hundreds of millivolts.Besides,the micro-surface potential of the rocks are heterogeneous,and both positive and negative points can be found.The existence and uneven distribution of micro-surface potential provide a robust physical basis for the electromagnetic radiation generated by rock fracture under loading.This study offers a new method for revealing the adsorption characteristics of unconventional gas reservoir rocks and the electromagnetic radiation mechanism of the rock fracture.

摘要： The effect of contact electrification on adhesion has been debated in recent years for gecko and bio-inspired dry adhesion material.To understand the fundamentals of this issue for Carbon Nanotube(CNT)dry adhesives,contact electrification and its relationship with adhesion are systematically studied using the first-principles calculation.Charge transfers from CNT or its special form,graphene,to the metal surface during the contact,and the transferred charge linearly correlates with the work function difference.Meanwhile,the adhesion energy is linearly related to the transferred charge for both CNT and graphene.More charge transfers from the flat graphene to metal surfaces than the curved CNT,leading to higher adhesion between graphene and metal surfaces.The curved structure of the CNT causes an irregular change of charge at the interface and hinders the charge transfer.Moreover,the curved structure induces electronic localization,which also decreases the interfacial charge transfer.The structure affects contact electrification,and hence adhesion is further demonstrated by the CNT with different deformation when contacting different surfaces.This study advances our understanding of contact electrification and its relationship with adhesion at the interface for bio-inspired carbon adhesive materials and sheds light on the control of them for engineering applications.

摘要： Natural rubber latex is the white liquid in the form of the colloidal dispersion of rubber globules suspended in the aqueous liquid. Produced in large quantities in Ivory Coast, the local transformation of natural latex has so far remained insignificant, although some attempts have been made to use it in the manufacture of flexible facade briquettes for rounded walls. Thus, this study aims to incorporate clay as a filler in natural latex for use as an adhesive for tile installation. To do this, different proportions of clay paste were added to the natural latex and the resulting mixtures were used to make the sample and tile adhesive. From the analysis of the results obtained, it appears that the samples with a clay paste density of 0.8 and 1 absorb less water and shows good pull-out strength. The mixtures of 30% and 35% latex and 0.8 and 1 clay paste density respectively have pullout stresses greater than 1 N/mm2. According to NF EN 1348, these adhesives can therefore be used as tile adhesive.

摘要： As additive manufacturing technologies advance,new opportunities are opening up for their application in the furniture industry.Wood remains one of the leading raw materials in the furniture industry;therefore,possible options for combining it with 3D printing have been researched.The bonding of 3D-printed polymer parts with wood or 3D printing with wood-plastic composites is already known,but in our research we attempted to directly 3D print polylactic acid(PLA)on wood surfaces.The effect of printing parameters,as well as the surface preparation of wood on the shear strength of the bond between wood and on-printed material was tested.Microscopic images of cross-sections of samples were analyzed.The results show that with a lower initial layer thickness(0.1 mm),a higher printing temperature(220°C),and with the use of polyvinyl acetate(PVAc)primer on the wood surface before 3D printing,a higher bond strength(5.4 MPa)was achieved,but the values for the bond strength remain low compared to the conventional bonding of wood to wood with PVAc adhesive(around 10 MPa).Microscopy studies revealed barely visible penetration of PLA into the lumens of the wood cells.However,the PVAc adhesive used as primer penetrated more into the cell lumens and served as interface layer between deposited melted PLA and the wood,thus creating stronger joints.

摘要： Cancer metastasis is still a major social issue with limited knowledge of the formation of tumors and their growth.In addition the formation of metastases is very difficult to understand,since it involves very complex physical mechanisms such as cellular interactions and cell rheology,which are flow-dependent.Previous studies investigated transendothelial migration using sophisticated techniques such as microfluidics,traction force microscopy(TFM)or Atomic Force Microscopy(AFM),combined with physical modeling.Here we summarize recent results and suggest new ways to investigate the precise mechanisms used by cancer cells to undergo transendothelial migration.

摘要： By modifying friction to the desired level,the application of friction modifiers(FMs)has been considered as a promising emerging tool in the railway engineering for increasing braking/traction force in poor adhesion conditions and mitigating wheel/rail interface deterioration,energy consumption,vibration and noise.Understanding the effectiveness of FMs in wheel–rail dynamic interactions is crucial to their proper applications in practice,which has,however,not been well explained.This study experimentally investigates the effects of two types of top-of-rail FM,i.e.FM-A and FM-B,and their application dosages on wheel–rail dynamic interactions with a range of angles of attack(AoAs)using an innovative well-controlled V-track test rig.The tested FMs have been used to provide intermediate friction for wear and noise reduction.The effectiveness of the FMs is assessed in terms of the wheel–rail adhesion characteristics and friction rolling induced axle box acceleration(ABA).This study provides the following new insights into the study of FM:the applications of the tested FMs can both reduce the wheel–rail adhesion level and change the negative friction characteristic to positive;stick–slip can be generated in the V-Track and eliminated by FM-A but intensified by FM-B,depending on the dosage of the FMs applied;the negative friction characteristic is not a must for stick–slip;the increase in ABA with AoA is insignificant until stick–slip occurs and the ABA can thus be influenced by the applications of FM.

摘要： Pelvic abdominal adhesion is a major problem in obstetrics and gynecology.The occurrence of adhesion complications,the difficulty and risk of adhesion reoperation,and the problem of postoperative adhesion not only cause great trouble to the physical and mental health of patients,but also increase the economic burden for the family and social medical system.

摘要： Focal adhesions are polyproteins linked to extracellular matrix and cytoskeleton,which play an important role in the process of transforming force signals into intracellular chemical signals and subsequently triggering related physiological or pathological reactions.The cytoskeleton is a network of protein fibers in the cytoplasm,which is composed of microfilaments,microtubules,intermediate filaments,and cross-linked proteins.It is a very important structure for cells to maintain their basic morphology.This review summarizes the process of fluid shear stress transduction mediated by focal adhesion and the key role of the cytoskeleton in this process,which focuses on the focal adhesion and cytoskeleton systems.The important proteins involved in signal transduction in focal adhesion are introduced emphatically.The relationship between focal adhesion and mechanical transduction pathways are discussed.In this review,we discuss the relationship between fluid shear stress and associated diseases such as atherosclerosis,as well as its role in clinical research and drug development.