"in plasmin-mediated extracellular fibrinolysis. Episodes may be triggered by minor trauma, eye surgery, or by systemic events such as infections or antifibrinolytic therapy. Histology shows amorphous subepithelial deposits of eosinophilic material consisting predominantly of fibrin. Ligneous conjunctivitis may be managed by topical treatments of plasminogen, topical and subconjunctival fresh frozen plasma, and fibrinolytic therapy. Ligneous conjunctivitis Ligneous conjunctivitis is a rare form of chronic conjunctivitis characterized by recurrent, fibrin-rich pseudomembranous lesions of wood-like consistency that develop mainly on the underside of the eyelid (tarsal conjunctiva). It is generally a systemic disease which may involve the periodontal tissue, the upper and"
"Lignin Lignin is a class of complex organic polymers that form key structural materials in the support tissues of vascular plants and some algae. Lignins are particularly important in the formation of cell walls, especially in wood and bark, because they lend rigidity and do not rot easily. Chemically, lignins are cross-linked phenolic polymers. Lignin was first mentioned in 1813 by the Swiss botanist A. P. de Candolle, who described it as a fibrous, tasteless material, insoluble in water and alcohol but soluble in weak alkaline solutions, and which can be precipitated from solution using acid. He named the substance"
"Lignocellulosic biomass Lignocellulose refers to plant dry matter (biomass), so called lignocellulosic biomass. It is the most abundantly available raw material on the Earth for the production of biofuels, mainly bio-ethanol. It is composed of carbohydrate polymers (cellulose, hemicellulose), and an aromatic polymer (lignin). These carbohydrate polymers contain different sugar monomers (six and five carbon sugars) and they are tightly bound to lignin. Lignocellulosic biomass can be broadly classified into virgin biomass, waste biomass and energy crops. Virgin biomass includes all naturally occurring terrestrial plants such as trees, bushes and grass. Waste biomass is produced as a low value byproduct"
"“lignine”, which is derived from the Latin word ""lignum"", meaning wood. It is one of the most abundant organic polymers on Earth, exceeded only by cellulose. Lignin constitutes 30% of non-fossil organic carbon and 20 to 35% of the dry mass of wood. The Carboniferous Period (geology) is in part defined by the evolution of lignin. The composition of lignin varies from species to species. An example of composition from an aspen sample is 63.4% carbon, 5.9% hydrogen, 0.7% ash (mineral components), and 30% oxygen (by difference), corresponding approximately to the formula (CHO). As a biopolymer, lignin is unusual because"
"Lignite Lignite, often referred to as brown coal, is a soft, brown, combustible, sedimentary rock formed from naturally compressed peat. It is considered the lowest rank of coal due to its relatively low heat content. It has a carbon content around 60–70 percent. It is mined all around the world and is used almost exclusively as a fuel for steam-electric power generation, but is also mined for its germanium content in China. Lignite is brownish-black in color and has a carbon content around 60–70 percent, a high inherent moisture content sometimes as high as 75 percent, and an ash content"
"lignite used in various types of jewelry. Lignite Lignite, often referred to as brown coal, is a soft, brown, combustible, sedimentary rock formed from naturally compressed peat. It is considered the lowest rank of coal due to its relatively low heat content. It has a carbon content around 60–70 percent. It is mined all around the world and is used almost exclusively as a fuel for steam-electric power generation, but is also mined for its germanium content in China. Lignite is brownish-black in color and has a carbon content around 60–70 percent, a high inherent moisture content sometimes as high"
"Lignan The lignans are a large group of polyphenols found in plants. Some examples of lignans are enterolignans, enterodiol and enterolactone. From ""lign-"" (Latin, ""wood"") + ""-an"" (chemical suffix). Plant lignans are polyphenolic substances derived from phenylalanine via dimerization of substituted cinnamic alcohols (see cinnamic acid), known as monolignols, to a dibenzylbutane skeleton 2. This reaction is catalysed by oxidative enzymes and is often controlled by dirigent proteins. Many natural products, known as phenylpropanoids, are built up of C6C3 units (""n""-propylbenzene skeleton 1) derived from cinnamyl units just as terpene chemistry builds on isoprene units. Structure 3 is a neolignan,"
"Lignum nephriticum Lignum nephriticum (Latin for ""kidney wood"") is a traditional diuretic that was derived from the wood of two tree species, the narra (""Pterocarpus indicus"") and the Mexican kidneywood (""Eysenhardtia polystachya ""). The wood is capable of turning the color of water it comes in contact with into beautiful opalescent hues that change depending on light and angle, the earliest known record of the phenomenon of fluorescence. Due to this strange property, it became well known in Europe from the 16th to the early 18th-century Europe. Cups made from ""lignum nephriticum"" were given as gifts to royalty. Water drunk"
"index for MgO-doped : formula_3, with: for congruent (CLN) and stochiometric (SLN). Lithium niobate Lithium niobate () is a compound of niobium, lithium, and oxygen. Its single crystals are an important material for optical waveguides, mobile phones, piezoelectric sensors, optical modulators and various other linear and non-linear optical applications. It is a human-made dielectric material that does not exist in nature. Lithium niobate is sometimes referred to by the brand name linobate. Lithium niobate is a colorless solid insoluble in water. It has a trigonal crystal system, which lacks inversion symmetry and displays ferroelectricity, the Pockels effect, the piezoelectric effect,"
"Cinnamic acid Cinnamic acid is an organic compound with the formula CHCH=CHCOOH. It is a white crystalline compound that is slightly soluble in water, and freely soluble in many organic solvents. Classified as an unsaturated carboxylic acid, it occurs naturally in a number of plants. It exists as both a ""cis"" and a ""trans"" isomer, although the latter is more common. Cinnamic acid is a central intermediate in the biosynthesis of myriad natural products include lignols (precursors to lignin and lignocellulose), flavonoids, isoflavonoids, coumarins, aurones, stilbenes, catechin, and phenylpropanoids. Its biosynthesis is performed by action of the enzyme phenylalanine ammonia-lyase"
"thus allowing for maximal extraction of sugars from lignocellulosic biomass. These sugars can then be fermented, leading to bio-ethanol. Lignocellulosic biomass Lignocellulose refers to plant dry matter (biomass), so called lignocellulosic biomass. It is the most abundantly available raw material on the Earth for the production of biofuels, mainly bio-ethanol. It is composed of carbohydrate polymers (cellulose, hemicellulose), and an aromatic polymer (lignin). These carbohydrate polymers contain different sugar monomers (six and five carbon sugars) and they are tightly bound to lignin. Lignocellulosic biomass can be broadly classified into virgin biomass, waste biomass and energy crops. Virgin biomass includes all"
"resulting in different linear free energy relationships. Cinnamic acid Cinnamic acid is an organic compound with the formula CHCH=CHCOOH. It is a white crystalline compound that is slightly soluble in water, and freely soluble in many organic solvents. Classified as an unsaturated carboxylic acid, it occurs naturally in a number of plants. It exists as both a ""cis"" and a ""trans"" isomer, although the latter is more common. Cinnamic acid is a central intermediate in the biosynthesis of myriad natural products include lignols (precursors to lignin and lignocellulose), flavonoids, isoflavonoids, coumarins, aurones, stilbenes, catechin, and phenylpropanoids. Its biosynthesis is performed"
"Lime (material) Lime is a calcium-containing inorganic mineral in which oxides, and hydroxides predominate. In the strict sense of the term, lime is calcium oxide or calcium hydroxide. It is also the name of the natural mineral (native lime) CaO which occurs as a product of coal seam fires and in altered limestone xenoliths in volcanic ejecta. The word ""lime"" originates with its earliest use as building mortar and has the sense of ""sticking or adhering"". These materials are still used in large quantities as building and engineering materials (including limestone products, cement, concrete, and mortar), as chemical feedstocks, and"
"Lithium niobate Lithium niobate () is a compound of niobium, lithium, and oxygen. Its single crystals are an important material for optical waveguides, mobile phones, piezoelectric sensors, optical modulators and various other linear and non-linear optical applications. It is a human-made dielectric material that does not exist in nature. Lithium niobate is sometimes referred to by the brand name linobate. Lithium niobate is a colorless solid insoluble in water. It has a trigonal crystal system, which lacks inversion symmetry and displays ferroelectricity, the Pockels effect, the piezoelectric effect, photoelasticity and nonlinear optical polarizability. Lithium niobate has negative uniaxial birefringence which"
"a matrix of hemicellulose and lignin. This type of structure and the chemical composition of them is responsible for the mechanical properties that can be observed. Because the natural fibers make hydrogen bonds between the long chains, they have the necessary stiffness and strength. The major constituents of natural fibers (lignocelluloses) are cellulose, hemicellulose, lignin, pectin and ash. The percentage of each component varies for each different type of fiber, however, generally, are around 60-80% cellulose, 5–20% lignin, and 20% of moisture, besides hemicellulose and a small percent of residual chemical components. The properties of the fiber change depending on"
"Lineatin Lineatin is a pheromone produced by female striped ambrosia beetle, ""Trypodendron lineatum"" Olivier. These kinds of beetles are responsible for extensive damage of coniferous forest infestation in Europe and North America. Since lineatin can act as lures used for mass-trapping of ""T. lineatum"", it is being studied to apply as a pest control reagent. Lineatin was first isolated in 1977 by MacConnell. The absolute configuration of the biologically active form was later determined as (+)-(1R,4S,5R,7R)-3,3,7-trimethyl-2,9- dioxatricyclo[3.3.1.0]nonane, whereas other enatinomers process no biological attraction activity. After the absolute structure was determined, lineatin quickly attracted considerable synthetic interests due to its"
"Lignosulfonates Lignosulfonates, or sulfonated lignin, (CAS number 8062-15-5) are water-soluble anionic polyelectrolyte polymers: they are byproducts from the production of wood pulp using sulfite pulping. Most delignification in sulfite pulping involves acidic cleavage of ether bonds, which connect many of the constituents of lignin. The electrophilic carbocations produced during ether cleavage react with bisulfite ions (HSO) to give sulfonates. The primary site for ether cleavage is the α-carbon (carbon atom attached to the aromatic ring) of the propyl (linear three carbon) side chain. The following structures do not specify the structure since lignin and its derivatives are complex mixtures: the"
"Leonardite Leonardite is a soft waxy, black or brown, shiny, vitreous mineraloid that is easily soluble in alkaline solutions. It is an oxidation product of lignite, associated with near-surface mining. It is a rich source of humic acid (up to 90%) and is used as a soil conditioner, as a stabilizer for ion-exchange resins in water treatment, in the remediation of polluted environments and as a drilling additive. It was named after A. G. Leonard, first director of the North Dakota Geological Survey, in recognition of his work on these deposits. Leonardite is found associated with near surface lignite deposits."
"Carpanone Carpanone is a naturally occurring lignan-type natural product most widely known for the remarkably complex way nature prepares it, and the similarly remarkable success that an early chemistry group, that of Orville L. Chapman, had at mimicking nature's pathway. Carpanone is an organic compound first isolated from the carpano trees (""Cinnamomum sp."") of Bougainville Island by Brophy and coworkers, trees from which the natural product derives its name. The hexacyclic lignan is one of a class of related diastereomers isolated from carpano bark as mixtures of equal proportion of the ""handedness"" of its components (i.e., racemic mixtures), and is"
"Longifolene Longifolene is the common (or trivial) chemical name of a naturally occurring, oily liquid hydrocarbon found primarily in the high-boiling fraction of certain pine resins. The name is derived from that of a pine species from which the compound was isolated, ""Pinus longifolia"" (obsolete name for ""Pinus roxburghii"" Sarg.) Chemically, longifolene is a tricyclic sesquiterpene. This molecule is chiral, and the enantiomer commonly found in pines and other higher plants exhibits a positive optical rotation of +42.73°. The other enantiomer (optical rotation −42.73°) is found in small amounts in certain fungi and liverworts. Longifolene is used in organic synthesis"
"ligands, in broad terms: Mineralogy, materials science, and solid state chemistry – as they apply to metal ions – are subsets of coordination chemistry in the sense that the metals are surrounded by ligands. In many cases these ligands are oxides or sulfides, but the metals are coordinated nonetheless, and the principles and guidelines discussed below apply. In hydrates, at least some of the ligands are water molecules. It is true that the focus of mineralogy, materials science, and solid state chemistry differs from the usual focus of coordination or inorganic chemistry. The former are concerned primarily with polymeric structures,"
"Bioproducts Bioproducts or bio-based products are materials, chemicals and energy derived from renewable biological resources. Biological resources include agriculture, forestry, and biologically-derived waste, and there are many other renewable bioresource examples. One of the scientific terms used to denote renewable bioresources is lignocellulose. Lignocellulosic tissues are biologically-derived natural resources containing some of the main constituents of the natural world. 1) Holocellulose is the carbohydrate fraction of lignocellulose that includes cellulose, a common building block made of sugar (glucose) that is the most abundant biopolymer, as well as hemicellulose. 2) Lignin is the second most abundant biopolymer. Cellulose and lignin are"
"Pyroligneous acid Pyroligneous acid, also called wood vinegar or wood acid, is a dark liquid produced by the destructive distillation of wood and other plant materials. The principal components of pyroligneous acid are acetic acid, acetone and methanol. It was once used as a commercial source for acetic acid. In addition, the vinegar often contains 80-90% water along with some 200 organic compounds. Pyroligneous acid (acetum lignorum) was investigated by German chemist Johann Rudolph Glauber. The acid was eaten as a substitute for vinegar. It was also used topically for treating wounds, ulcers and other ailments. A salt can be"
"Linalyl acetate Linalyl acetate is a naturally occurring phytochemical found in many flowers and spice plants. It is one of the principal components of the essential oils of bergamot and lavender. Chemically, it is the acetate ester of linalool, and the two often occur in conjunction. Synthetic linalyl acetate is sometimes used as an adulterant in essential oils to make them more marketable. For example, it may be added to lavendin oil which is then sold as more desirable lavender oil. The chemical tastes similar to how it smells with a pleasant fruity odor reminiscent of bergamot mint oil. It"
"of two species yielding the true lignum vitae, the other being ""Guaiacum sanctum"". Guaiac, a natural resin extracted from the wood, is a colorless compound that turns blue when placed in contact with substances that have peroxidase activity and then are exposed to hydrogen peroxide. Guaiac cards are impregnated with the resin and are used in determining whether stool contains blood. The heme portion of hemoglobin contains peroxidase and will catalyze the oxidation of guaiaconic acid when hydrogen peroxide is placed on the Guaiac card if blood is present in the stool. Roughbark lignum-vitae was listed as an endangered species"
"Linear acetylenic carbon Linear acetylenic carbon (LAC), also called carbyne, is an allotrope of carbon that has the chemical structure (−C≡C−) as a repeating chain, with alternating single and triple bonds. It would thus be the ultimate member of the polyyne family. This polymeric carbyne is of considerable interest to nanotechnology as its Young's modulus is – forty times that of diamond. It has also been identified in interstellar space; however, its existence in condensed phases has been contested recently, as such chains would crosslink exothermically (and perhaps explosively) if they approached each other. The first claims of detection of"
"Pulvinone Pulvinone, an organic compound belonging to the esters, lactones, alcohols and butenolides classes, is a yellow crystalline solid. Although the pulvinone is not a natural product, several naturally occurring hydroxylated derivatives are known. These hydroxylated pulvinones are produced by fungal species, such as the in Europe common Larch Bolete (""Boletus elegans"", also known as ""Suillus grevillei""), or by moulds such as ""Aspergillus terreus"". Fungi - such as boleti -, moulds and lichens produce a wide range of pigments made up of one (monomer) or several (oligomers) units of pulvinic acid. In 1831, in the course of a study of"
"gives its name to the langbeinites, a family of substances with the same cubic structure, a tetrahedral anion, and large and small cations. Related substances include hydrated salts leonite (KMg(SO)·4HO) and picromerite (KMg(SO)·6HO). Langbeinite Langbeinite is a potassium magnesium sulfate mineral with the chemical formula KMg(SO). Langbeinite crystallizes in the isometric-tetartoidal system as transparent colorless or white with pale tints of yellow to green and violet crystalline masses. It has a vitreous luster. The Mohs hardness is 3.5 to 4 and the specific gravity is 2.83. The crystals are piezoelectric. The mineral is an ore of potassium and occurs in"
"Lawsone Lawsone (2-hydroxy-1,4-naphthoquinone), also known as hennotannic acid, is a red-orange dye present in the leaves of the henna plant (""Lawsonia inermis"") as well as in the flower of water hyacinth (""Eichhornia crassipes""). Humans have used henna extracts containing lawsone as hair and skin dyes for more than 5000 years. Lawsone reacts chemically with the protein keratin in skin and hair, in a process known as Michael addition, resulting in a strong permanent stain that lasts until the skin or hair is shed. The darker colored ink is due to more lawsone-keratin interactions occurring, which evidently break down as the"
"Ligand In coordination chemistry, a ligand is an ion or molecule (functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's electron pairs. The nature of metal–ligand bonding can range from covalent to ionic. Furthermore, the metal–ligand bond order can range from one to three. Ligands are viewed as Lewis bases, although rare cases are known to involve Lewis acidic ""ligands"". Metals and metalloids are bound to ligands in virtually all circumstances, although gaseous ""naked"" metal ions can be generated"
"of its heterogeneity and lack of a defined primary structure. Its most commonly noted function is the support through strengthening of wood (mainly composed of xylem cells and lignified sclerenchyma fibres) in vascular plants. The lignols that crosslink are of three main types, all derived from phenylpropane: 4-hydroxy-3-methoxyphenylpropane, 3,5-dimethoxy-4-hydroxyphenylpropane, and 4-hydroxyphenylpropane. The former tends to be more prevalent in conifers and the latter in hardwoods. Lignin is a cross-linked polymer with molecular masses in excess of 10,000 u. It is relatively hydrophobic and rich in aromatic subunits. The degree of polymerisation is difficult to measure, since the material is heterogeneous."
"Lithium amide Lithium amide is an inorganic compound with the chemical formula LiNH, i.e. it is composed of a lithium cation, and the conjugate base of ammonia. It is a white solid with a tetragonal crystal structure. The anionic conjugate bases of amines are known as amides. Thus a ""lithium amide"" may also refer to any compound in the class of the lithium salt of an amine. These chemicals have the general form LiNR, with the chemical lithium amide itself as the parent structure. Common lithium amides include lithium diisopropylamide (LDA), lithium tetramethylpiperidide (LiTMP), and lithium hexamethyldisilazide (LiHMDS). Lithium amide"
"Linoleic acid Linoleic acid (LA), a carboxylic acid, is a polyunsaturated omega-6 fatty acid, an 18-carbon chain with two double bonds in cis configuration. A shorthand notation like ""18:2 (n-6)"" or ""18:2 ""cis""-9,12"" may be used in literature. It typically occurs in nature as a triglyceride ester; free fatty acids are typically low in foods. It is very soluble in acetone, benzene, diethyl ether and ethanol. Linoleic acid belongs to one of the two essential fatty acids, which means that the human body cannot synthesize it from other food components. The word ""linoleic"" derived from the Greek word ""linon"" (flax)."