Exfoliation (material Science)
Exfoliation can refer to: * Exfoliation (botany), the loss of leaves (or, in some cases, pieces of bark) from a plant * Exfoliation (cosmetology), a cosmetic technique that aims to remove dead skin from the body and face * Exfoliation (geology), a process resulting in parallel fractures in the surface of rock * Exfoliation corrosion (metallurgy), a severe type of intergranular corrosion * Exfoliation - Intercalation (chemistry), the complete separation of the layers of a material * Exfoliation syndrome, an eye disease See also * Exfoliative dermatitis, sometimes known as erythroderma Erythroderma is an inflammatory skin disease with redness and scaling that affects nearly the entire cutaneous surface.Freedberg, et al. (2003). ''Fitzpatrick's Dermatology in General Medicine''. (6th ed.). McGraw-Hill. p. 436. . This term applie ...

Exfoliation (botany)
Exfoliation (from the term "foliate", meaning “related to leaves”) means the removal or loss of leaves from a plant. It is used both to describe the loss of a leaves as a natural part of a plant's life cycle (such as in the case of deciduous trees which lose their leaves in the autumn) or because of some trauma or outside cause (such as dehydration, an infestation of caterpillars or hurricane-force winds). In arboriculture, the term “exfoliating bark” describes the natural process and condition of the bark peeling-away from a tree trunk, typically in large pieces that remain partially attached to the trunk until such time as they are completely detached by the elements or the eventual and subsequent exfoliation of additional layers of bark. Examples of trees with exfoliating bark are the paperbark maple and various species of Plane (Sycamore) and birch A birch is a thin-leaved deciduous hardwood tree of the genus ''Betula'' (), in the family Betulaceae, which also ...
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Exfoliation (cosmetology)
Exfoliation is the removal of dead skin cells and built-up dirt from the skin's surface. The term comes from the Latin word ''exfoliare'' (to strip off leaves). This is a regular practice within the cosmetic industry, both for its outcome of promoting skin regeneration as well as providing a deep cleanse of the skin barrier. Being used in facials, this process can be achieved by mechanical or chemical means, such as microdermabrasion or chemical peels. Exfoliants are advertised as treatments that enhance beauty and promote a youthful and healthy appearance. History Exfoliation was first practiced among the ancient Egyptians. This was also used in Asia, specifically in China, during the Qing Dynasty (1644–1944). Mechanical Exfoliation Mechanical exfoliation methods involve physically scrubbing the skin with an abrasive material. These types of exfoliants include microfiber cloths, adhesive exfoliation sheets, micro-bead facial scrubs, crêpe paper, crushed apricot kernel or a ...
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Exfoliation (geology)
Exfoliation joints or sheet joints are surface-parallel fracture systems in rock, and often leading to erosion of concentric slabs. ''(See Joint (geology)).'' General characteristics of exfoliation joints * Commonly follow topography. * Divide the rock into sub-planar slabs. * Joint spacing increases with depth from a few centimeters near the surface to a few meters * Maximum depth of observed occurrence is around 100 meters. * Deeper joints have a larger radius of curvature, which tends to round the corners of the landscape as material is eroded * Fracture mode is tensile * Occur in many different lithologies and climate zones, not unique to glaciated landscapes. * Host rock is generally sparsely jointed, fairly isotropic, and has high compressive strength. * Can have concave and convex upwards curvatures. * Often associated with secondary compressive forms such as arching, buckling, and A-tents (buckled slabs) Formation of exfoliation joints Despite their common occurrenc ...
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Exfoliation Corrosion (metallurgy)
In metallurgy, exfoliation corrosion (also called lamellar corrosion) is a severe type of intergranular corrosion that raises surface grains from metal by forming corrosion products at grain boundaries under the surface. It is frequently found on extruded Extrusion is a process used to create objects of a fixed cross-sectional profile by pushing material through a die of the desired cross-section. Its two main advantages over other manufacturing processes are its ability to create very complex c ... sections where grain thickness is not as thick as the rolled grain. It can affect aircraft structures, marine vessels, heaters and other objects. References Corrosion {{corrosion-stub ...
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Layered Materials
In material science, layered materials are solids with highly anisotropic bonding, in which two-dimensional sheets are internally strongly bonded, but only weakly bonded to adjacent layers. Owing to their distinctive structures, layered materials are often suitable for intercalation reactions. One large family of layered materials are metal dichalcogenides. In such materials, the M-chalcogen bonding is strong and covalent. These materials exhibit anisotropic electronic properties such as thermal and electrical conductivity. Exfoliation Because the layers bond to each other by relatively weak van der Waals forces, some layered materials are amenable to exfoliation, the complete separation of the layers of the material. Exfoliation can be done using sonication, mechanical, hydrothermal, electrochemical, laser-assisted, and microwave-assisted methods. Typically aggressive conditions are required involving highly polar solvents and reagents. In the ideal case, exfoliation affor ...
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Exfoliation Syndrome
Pseudoexfoliation syndrome, often abbreviated as PEX and sometimes as PES or PXS, is an aging-related systemic disease manifesting itself primarily in the eyes which is characterized by the accumulation of microscopic granular amyloid-like protein fibers. Its cause is unknown, although there is speculation that there may be a genetic basis. It is more prevalent in women than men, and in persons past the age of seventy. Its prevalence in different human populations varies; for example, it is prevalent in Scandinavia. The buildup of protein clumps can block normal drainage of the eye fluid called the aqueous humor and can cause, in turn, a buildup of pressure leading to glaucoma and loss of vision (pseudoexfoliation glaucoma, exfoliation glaucoma). As worldwide populations become older because of shifts in demography, PEX may become a matter of greater concern. Signs and symptoms Patients may have no specific symptoms. In some cases, patients may complain of lessened visual acuity o ...
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