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Note 1: Adhesion requires energy that can come from chemical and/or physical linkages, the latter being reversible when enough energy is applied. Note 2: In biology, adhesion reflects the behavior of cells shortly after contact to the surface. Note 3: In surgery, adhesion is used when two tissues fuse unexpectedly. [1]
Many mechanics theories exist on this topic. The majority of them attribute the increase in adhesion strength to the greater thermodynamic stability of the impurity element bonded with oxygen than the metal bonded to the oxygen. [2] [8] Inserting yttrium into nickel alloys to strengthen the oxide adhesion is an example of the reactive element ...
Likewise, contaminants, especially those which, due to their low surface tension, counteract wetting by the adhesive (for example, oils, release agents, etc.) hinder the adhesion interaction. Contaminants form, as it were, a barrier between the adhesive and the substrate which cannot be bridged by the adhesion forces due to their short reach.
Cohesion, along with adhesion (attraction between unlike molecules), helps explain phenomena such as meniscus, surface tension and capillary action. Mercury in a glass flask is a good example of the effects of the ratio between cohesive and adhesive forces.
Schematic of cell adhesion. Cell adhesion is the process by which cells interact and attach to neighbouring cells through specialised molecules of the cell surface. This process can occur either through direct contact between cell surfaces such as cell junctions or indirect interaction, where cells attach to surrounding extracellular matrix, a gel-like structure containing molecules released ...
Mucoadhesion involves several types of bonding mechanisms, and it is the interaction between each process that allows for the adhesive process. The major categories are wetting theory, adsorption theory, diffusion theory, electrostatic theory, and fracture theory. [5]
The process is highly regulated by cell adhesion molecules, particularly, the addressin also known as MADCAM1. This antigen is known for its role in tissue-specific adhesion of lymphocytes to high endothelium venules. [23] Through these interactions they play a crucial role in orchestrating circulating lymphocytes.
The strength of adhesion depends on many factors, including the means by which it occurs. In some cases, an actual chemical bond occurs between adhesive and substrate. Thiolated polymers, for example, form chemical bonds with endogenous proteins such as mucus glycoproteins, integrins or keratins via disulfide bridges. [41]