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Diode-pumped solid-state laser
A diode-pumped solid-state laser (DPSSL) is a solid-state laser, typically Nd:YAG, pumped by laser diodes rather than flashlamps, giving roughly ten times the efficiency and far longer lifetimes.
Diol
A diol is an organic compound containing two hydroxy groups, generally assumed alcoholic; aliphatic diols are also called glycols, ranging from ethylene glycol, the base of antifreeze, to sugar alcohols.
Diol reactivity and derivatives
Diol reactivity and derivatives covers the reactions of molecules bearing two hydroxyl groups, including cyclic acetal formation, carbonate synthesis, oxidative cleavage, and the pinacol rearrangement.
Dion Gijswijt
Dion Gijswijt is a Dutch mathematician and professor at TU Delft known for the 2016 cap set bound proved with Jordan Ellenberg, for Gijswijt's sequence, and for winning the 2019 N.G. de Bruijn Prize.
Dione (moon)
Dione is the fourth-largest moon of Saturn, an icy satellite about 1,123 km across that orbits every 2.7 days and is known for its bright wispy terrain.
Dionysius Exiguus
Dionysius Exiguus, also known as Dennis the Short, was a sixth-century monk and computist in Rome who introduced the Anno Domini system for counting years from the birth of Christ.
Dionýz Ilkovič
Dionýz Ilkovič was a Slovak physicist who derived the Ilkovič equation of polarography in 1934 and is regarded as the founder of physics in Slovakia.
Diophantine approximation
Diophantine approximation is the branch of number theory studying how closely a real number can be approximated by rationals with bounded denominators; key results include Dirichlet's and Roth's theorems.
Diophantine condition
A Diophantine condition is an arithmetic lower bound keeping frequency vectors from being too closely approximated by rationals, used in KAM theory to control small divisors.
Diophantine equation
A Diophantine equation, or Diophantine analysis, is a polynomial equation with rational coefficients whose integer or rational solutions are sought, as in Fermat's Last Theorem, proved in 1994.
Diophantine geometry
Diophantine geometry studies integral and rational points on systems of polynomial equations through algebraic geometry, named for Diophantus of Alexandria; Serge Lang coined the term in 1962.
Diophantine set
A Diophantine set is a set of tuples of positive integers that forms part of the solution set of a polynomial equation with integer coefficients, central to Hilbert's tenth problem.
Diophantus (Διόφαντος)
Diophantus (Διόφαντος), also known as Diophantus of Alexandria, was a Greek mathematician active about 250 CE, sometimes called the father of algebra, best known for his Arithmetica.
Diopside
Diopside is a calcium magnesium silicate pyroxene, MgCaSi₂O₆, common in olivine-rich basalts and metamorphosed limestones worldwide, cut into vivid green gemstones, and used to study Earth's mantle formation conditions.
Dioptase
Dioptase is a hydrated copper cyclosilicate mineral with intense emerald-green to blue-green crystals, named by René Just Haüy in 1797 and prized as a collector's specimen.
Dioptre
The dioptre, spelled diopter in American English, is the unit of optical power equal to the reciprocal of focal length in meters, standard in eyeglass and contact lens prescriptions.
Diorite
Diorite is a coarse-grained intrusive igneous rock of intermediate composition, made mainly of plagioclase feldspar and dark minerals, with a speckled salt-and-pepper appearance; its fine-grained volcanic equivalent is andesite.
Diosgenin
Diosgenin is a steroidal sapogenin, a plant-derived steroid found mainly in Dioscorea wild yams and used as the starting material for cortisone, progesterone, and other steroid drugs.
Diosmin
Diosmin is a flavone glycoside found in citrus peel, used as a venoactive drug for chronic venous insufficiency and hemorrhoids and sold over the counter.
Dioxolane
1,3-Dioxolane is a five-membered cyclic acetal with two oxygen atoms in its ring, a clear liquid used as an industrial solvent and a protecting group for aldehydes and ketones.
Dipankar Das Sarma
Dipankar Das Sarma, often published as D. D. Sarma, is an Indian condensed matter physicist and solid-state chemist at the Indian Institute of Science, Bengaluru.
Dipentaerythritol
Dipentaerythritol is an ether-linked polyol with six hydroxyl groups on a compact C10 skeleton, formed as a byproduct of pentaerythritol production and used in polyesters, PVC stabilizers, coatings, and lubricants.
Diphenyl diselenide
Diphenyl diselenide (Ph2Se2) is a stable, commercially available organoselenium compound used as a reagent in organic synthesis and as a reference antioxidant and glutathione peroxidase mimic.
Diphenyl disulfide
Diphenyl disulfide, also called phenyl disulfide, is the simplest aromatic disulfide, a white crystalline organosulfur compound melting near 60 °C used in radical chemistry and sulfenylation.
Diphenyl ether
Diphenyl ether, also called diphenyl oxide or phenoxybenzene, is a colorless aromatic ether used as a heat transfer fluid, notably in DOWTHERM A, and in soap perfumery.
Diphenyl sulfide
Diphenyl sulfide, also called phenyl sulfide, is an organosulfur compound of formula C12H10S with two phenyl groups joined by a sulfur atom, a colorless liquid with an unpleasant odor.
Diphenylamine
Diphenylamine, also called N-phenyl aniline, is an aromatic secondary amine, (C₆H₅)₂NH, used as a propellant stabilizer, antioxidant, dye intermediate, and post-harvest scald treatment for apples.
Diphenyleneiodonium
Diphenyleneiodonium, also called dibenziodolium, is a cyclic diaryliodonium cation that covalently inhibits flavin-containing enzymes; it is the most commonly used inhibitor of NADPH oxidase in experimental research.
Diphenylmethane
Diphenylmethane, also called benzylbenzene, is an aromatic hydrocarbon, C13H12, with a central methylene group linking two phenyl rings, used as a fragrance fixative, dye carrier, and chemical intermediate.
Diphenylphosphine
Diphenylphosphine, IUPAC name diphenylphosphane (Ph₂PH), is a colorless, air-sensitive, pyrophoric secondary phosphine liquid with a boiling point of 280 °C, used chiefly to make phosphine ligands and as a hydrophosphination reagent.