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Urushiol
Urushiol is an oily mixture of organic compounds with allergenic properties found in plants of the family Anacardiaceae, especially '' Toxicodendron'' ''spp.'' (e.g., poison oak, Chinese lacquer tree, poison ivy, poison sumac), ''Comocladia spp.'' (maidenplums), ''Metopium spp''. (poisonwood), and also in parts of the mango tree as well as the fruit of the cashew tree. In most individuals, urushiol causes an allergic skin rash on contact, known as urushiol-induced contact dermatitis. The name urushiol is derived from the Japanese word for the lacquer tree, . The oxidation and polymerization of urushiol in the tree's sap in the presence of moisture allows it to form a hard lacquer, which is used to produce traditional Chinese, Korean and Japanese lacquerware. History Although urushiol-containing lacquers and their skin-irritating properties were well known in East Asia for several millennia, its first recorded Western texts were in 1624 by John Smith and he initial ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Urushiol
Urushiol is an oily mixture of organic compounds with allergenic properties found in plants of the family Anacardiaceae, especially '' Toxicodendron'' ''spp.'' (e.g., poison oak, Chinese lacquer tree, poison ivy, poison sumac), ''Comocladia spp.'' (maidenplums), ''Metopium spp''. (poisonwood), and also in parts of the mango tree as well as the fruit of the cashew tree. In most individuals, urushiol causes an allergic skin rash on contact, known as urushiol-induced contact dermatitis. The name urushiol is derived from the Japanese word for the lacquer tree, . The oxidation and polymerization of urushiol in the tree's sap in the presence of moisture allows it to form a hard lacquer, which is used to produce traditional Chinese, Korean and Japanese lacquerware. History Although urushiol-containing lacquers and their skin-irritating properties were well known in East Asia for several millennia, its first recorded Western texts were in 1624 by John Smith and he initial ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Urushiol-induced Contact Dermatitis
Urushiol-induced contact dermatitis (also called Toxicodendron dermatitis or Rhus dermatitis) is a type of allergic contact dermatitis caused by the oil urushiol found in various plants, most notably species of the genus '' Toxicodendron'': poison ivy, poison oak, poison sumac, and the Chinese lacquer tree. The name is derived from the Japanese word for the sap of the Chinese lacquer tree, ''urushi''. Other plants in the sumac family (including mango, pistachio, the Burmese lacquer tree, the India marking nut tree, and the shell of the cashew) also contain urushiol, as do unrelated plants such as ''Ginkgo biloba.'' As is the case with all contact dermatitis, urushiol-induced allergic rashes are a Type IV hypersensitivity reaction, also known as delayed-type hypersensitivity. Symptoms include itching, inflammation, oozing, and, in severe cases, a burning sensation. The American Academy of Dermatology estimates that there are up to 50 million cases of urushiol-induced dermat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lacquer
Lacquer is a type of hard and usually shiny coating or finish applied to materials such as wood or metal. It is most often made from resin extracted from trees and waxes and has been in use since antiquity. Asian lacquerware, which may be called "true lacquer", are objects coated with the treated, dyed and dried sap of '' Toxicodendron vernicifluum'' or related trees, applied in several coats to a base that is usually wood. This dries to a very hard and smooth surface layer which is durable, waterproof, and attractive in feel and look. Asian lacquer is sometimes painted with pictures, inlaid with shell and other materials, or carved, as well as dusted with gold and given other further decorative treatments. In modern techniques, lacquer means a range of clear or pigmented coatings that dry by solvent evaporation to produce a hard, durable finish. The finish can be of any sheen level from ultra matte to high gloss, and it can be further polished as required. Lacquer finish ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lacquer
Lacquer is a type of hard and usually shiny coating or finish applied to materials such as wood or metal. It is most often made from resin extracted from trees and waxes and has been in use since antiquity. Asian lacquerware, which may be called "true lacquer", are objects coated with the treated, dyed and dried sap of '' Toxicodendron vernicifluum'' or related trees, applied in several coats to a base that is usually wood. This dries to a very hard and smooth surface layer which is durable, waterproof, and attractive in feel and look. Asian lacquer is sometimes painted with pictures, inlaid with shell and other materials, or carved, as well as dusted with gold and given other further decorative treatments. In modern techniques, lacquer means a range of clear or pigmented coatings that dry by solvent evaporation to produce a hard, durable finish. The finish can be of any sheen level from ultra matte to high gloss, and it can be further polished as required. Lacquer finish ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Toxicodendron Radicans
''Toxicodendron radicans'', commonly known as eastern poison ivy or poison ivy, is an allergenic Asian and Eastern North American flowering plant in the genus ''Toxicodendron''. The species is well known for causing urushiol-induced contact dermatitis, an itchy, irritating, and sometimes painful rash, in most people who touch it. The rash is caused by urushiol, a clear liquid compound in the plant's sap. The species is variable in its appearance and habit, and despite its common name, it is not a true ivy (''Hedera''), but rather a member of the cashew and pistachio family (Anacardiaceae). ''T. radicans'' is commonly eaten by many animals and the seeds are consumed by birds, but poison ivy is most often thought of as an unwelcome weed. It is a different species from western poison ivy, '' T. rydbergii'', which has similar effects. Description Numerous subspecies and/or varieties of ''T. radicans'' are known. They can be found growing in any of the following forms, al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Toxicodendron Vernicifluum
''Toxicodendron vernicifluum'' (formerly ''Rhus verniciflua''), also known by the common name Chinese lacquer tree, is an Asian tree species of genus '' Toxicodendron'' native to China and the Indian subcontinent, and cultivated in regions of China, Japan and Korea. Other common names include ''Japanese lacquer tree'', ''Japanese sumac'', and ''varnish tree''. The trees are cultivated and tapped for their toxic sap, which is used as a highly durable lacquer to make Chinese, Japanese, and Korean lacquerware. The trees grow up to 20 metres tall with large leaves, each containing from 7 to 19 leaflets (most often 11–13). The sap contains the allergenic compound urushiol, which gets its name from this species' Japanese name urushi (); "urushi" is also used in English as a collective term for all kinds of Asian lacquerware made from the sap of this and related Asian tree species, as opposed to European "lacquer" or Japanning made from other materials. Urushiol is also the oil fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Toxicodendron
''Toxicodendron'' is a genus of flowering plants in the sumac family, Anacardiaceae. It contains trees, shrubs and woody vines, including poison ivy, poison oak, and the lacquer tree. All members of the genus produce the skin-irritating oil urushiol, which can cause a severe allergic reaction. The generic name is derived from the Greek words τοξικός (''toxikos''), meaning "poison," and δένδρον (''dendron''), meaning "tree". The best known members of the genus in North America are poison ivy ''(T. radicans)'', practically ubiquitous throughout most of eastern North America, and western poison oak ('' T. diversilobum''), similarly ubiquitous throughout much of the western part of the continent. The genus is a member of the '' Rhus complex'', and has at various times been categorized as being either its own genus or a sub-genus of ''Rhus.'' There is evidence which points to keeping ''Toxicodendron'' as a separate monophyletic genus, but researchers have sta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cashew
The cashew tree (''Anacardium occidentale'') is a tropical evergreen tree native to South America in the genus ''Anacardium'' that produces the cashew seed and the cashew apple accessory fruit. The tree can grow as tall as , but the dwarf cultivars, growing up to , prove more profitable, with earlier maturity and greater yields. The cashew seed is commonly considered a snack nut (cashew nut) eaten on its own, used in recipes, or processed into cashew cheese or cashew butter. Like the tree, the nut is often simply called a cashew. Cashew allergies are triggered by the proteins found in tree nuts, and cooking often does not remove or change these proteins. In 2019, four million tonnes of cashew nuts were produced globally, with Ivory Coast and India as the leading producers. As well as the nut and fruit, the plant has several other uses. The shell of the cashew seed yields derivatives that can be used in many applications including lubricants, waterproofing, paints, and, s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Allergic Contact Dermatitis
Allergic contact dermatitis (ACD) is a form of contact dermatitis that is the manifestation of an allergic response caused by contact with a substance; the other type being irritant contact dermatitis (ICD). Although less common than ICD, ACD is accepted to be the most prevalent form of immunotoxicity found in humans. By its allergic nature, this form of contact dermatitis is a hypersensitive reaction that is atypical within the population. The mechanisms by which these reactions occur are complex, with many levels of fine control. Their immunology centres on the interaction of immunoregulatory cytokines and discrete subpopulations of T lymphocytes. Signs and symptoms The symptoms of allergic contact dermatitis are very similar to the ones caused by irritant contact dermatitis, which makes the first even harder to diagnose. The first sign of allergic contact dermatitis is the presence of the rash or skin lesion at the site of exposure. Depending on the type of allergen causing i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Toxicodendron Vernix
''Toxicodendron vernix'', commonly known as poison sumac, or swamp-sumach, is a woody shrub or small tree growing to 9 metres (30 feet) tall. It was previously known as ''Rhus vernix''. This plant is also known as thunderwood, particularly where it occurs in the southern United States. All parts of the plant contain a resin called urushiol that causes skin and mucous membrane irritation to humans. When the plant is burned, inhalation of the smoke may cause the rash to appear on the lining of the lungs, causing extreme pain and possibly fatal respiratory difficulty. Description Poison sumac is a shrub or small tree, growing up to nearly in height. Each pinnate leaf has 7–13 leaflets, each of which is long. These are oval-to-oblong; acuminate (tapering to a sharp point); cuneate (wedge-shaped) at the base; undulate (wavy-edged); with an underside that is glabrous (hairless) or slightly pubescent (down-like hair) beneath. The stems along the leaflets are red and the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxidation
Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a decrease in the oxidation state. There are two classes of redox reactions: * ''Electron-transfer'' – Only one (usually) electron flows from the reducing agent to the oxidant. This type of redox reaction is often discussed in terms of redox couples and electrode potentials. * ''Atom transfer'' – An atom transfers from one substrate to another. For example, in the rusting of iron, the oxidation state of iron atoms increases as the iron converts to an oxide, and simultaneously the oxidation state of oxygen decreases as it accepts electrons released by the iron. Although oxidation reactions are commonly associated with the formation of oxides, other chemical species can serve the same function. In hydrogenation, C=C (and other) bonds a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Specific Gravity
Relative density, or specific gravity, is the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity for liquids is nearly always measured with respect to water at its densest (at ); for gases, the reference is air at room temperature (). The term "relative density" (often abbreviated r.d. or RD) is often preferred in scientific usage, whereas the term "specific gravity" is deprecated. If a substance's relative density is less than 1 then it is less dense than the reference; if greater than 1 then it is denser than the reference. If the relative density is exactly 1 then the densities are equal; that is, equal volumes of the two substances have the same mass. If the reference material is water, then a substance with a relative density (or specific gravity) less than 1 will float in water. For example, an ice cube, with a relative density of about 0.91, will float. A substance with a relative density greater ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
