42,772 articles
Overpotential
Overpotential, symbol η, is the extra voltage beyond the thermodynamic requirement needed to drive an electrode reaction at a given rate, and the main benchmark for comparing electrocatalysts.
Overpressure (geology)
Overpressure, also called geopressure, is fluid pressure in a sedimentary basin exceeding hydrostatic pressure at a given depth. It is a drilling hazard behind many well blowouts.
Overshoot (signal)
Overshoot in signal processing is the excursion of a reconstructed or filtered signal above its true value near a transition, paired with an undershoot below it.
Overshooting top
An overshooting top is the dome-like protrusion of a thunderstorm's cloud top above the anvil, driven by a very strong updraft and used as a satellite indicator of storm intensity.
Overtone
An overtone, also known as an upper partial or superharmonic, is any frequency component of a complex sound above its fundamental; overtones largely determine timbre, or tone color.
Overturn
Overturn: in oceanography, the mixing of stratified water due to density instability, and the related global overturning circulation (thermohaline circulation, AMOC) that sinks dense polar water and redistributes heat, salt, and carbon worldwide.
Overturning in the Subpolar North Atlantic Program
The Overturning in the Subpolar North Atlantic Program (OSNAP) is an international program measuring the Atlantic meridional overturning circulation with a moored array since 2014.
Overview of statistics and probability journals
Statistics and probability journals are the peer-reviewed periodicals where statistical theory, methods, and applications are published, led by titles like JASA, Biometrika, and the Annals of Statistics.
Ovoid (projective geometry)
An ovoid in finite projective geometry is a set of q²+1 points in PG(3,q) with no three collinear, used to build inversive planes, generalized quadrangles, and error-correcting codes.
Owen Brian Toon
Owen Brian Toon is an American atmospheric scientist at the University of Colorado Boulder known for nuclear winter research and work on clouds, aerosols, and ozone.
Owen Chamberlain
Owen Chamberlain (1920–2006) was an American experimental physicist at UC Berkeley who co-discovered the antiproton and shared the 1959 Nobel Prize in Physics with Emilio Segrè.
Owen Gingerich
Owen Gingerich (1930–2023) was an American astronomer and historian of science at Harvard, best known for his three-decade census of copies of Copernicus's De revolutionibus.
Owen Martin Phillips
Owen Martin Phillips (1930–2010) was an Australian-born physical oceanographer at Johns Hopkins University, known for his 1957 resonance theory of wind-generated ocean waves and the standard reference The Dynamics of the Upper Ocean.
Owen Thomas Jones
Owen Thomas Jones (1878–1967) was a Welsh geologist who established the Ordovician and Silurian succession of central Wales and became the first Professor of Geology at Aberystwyth.
Owen Willans Richardson
Owen Willans Richardson (1879–1959) was an English physicist who won the 1928 Nobel Prize in Physics for discovering Richardson's law of thermionic emission, the basis of vacuum-tube technology.
Ox (牛) (zodiac)
The Ox (牛, niu) is the second animal of the Chinese zodiac, paired with the earthly branch Chou; recent Ox years include 2009, 2021, and 2033.
Oxadiazole
Oxadiazole (C2H2N2O) is a five-membered heteroaromatic ring containing two nitrogens and one oxygen, existing in four isomers, among the most used heterocycles in medicinal chemistry and materials science.
Oxalate
Oxalate, also called ethanedioate or the oxalate ion, is the dianion of oxalic acid, best known as the main component of most human kidney stones.
Oxalic acid
Oxalic acid (ethanedioic acid, C2H2O4) is the simplest dicarboxylic acid, a colorless crystalline solid that occurs widely in plants as calcium oxalate and can damage the kidneys in high doses.
Oxaloacetic acid
Oxaloacetic acid, also called oxaloacetate or OAA, is a four-carbon dicarboxylic acid that starts and ends the citric acid cycle and is the first committed intermediate of gluconeogenesis.
Oxanorbornadiene
Oxanorbornadiene (7-oxabicyclo[2.2.1]hepta-2,5-diene) is a strained bicyclic organic compound made by Diels-Alder reaction of furan with an alkyne; its dicarboxylate derivatives serve as cleavable, electrophilic linkers in bioconjugation and drug delivery.
Oxazole
Oxazole (C₃H₃NO) is a five-membered aromatic heterocycle containing one oxygen and one nitrogen atom separated by a carbon, common in pharmaceuticals and marine natural products.
Oxazolidine
Oxazolidine is a saturated five-membered heterocyclic compound with one oxygen and one nitrogen atom, made by condensing 1,2-amino alcohols with aldehydes or ketones, and used as chiral auxiliaries in asymmetric synthesis.
Oxazolidinone
An oxazolidinone is a five-membered cyclic carbamate important in asymmetric synthesis as the Evans chiral auxiliary and as the core of antibiotics such as linezolid, approved in 2000.
Oxazolone
Oxazolone (4-ethoxymethylene-2-phenyl-5(4H)-oxazolone) is a heterocyclic compound of the azlactone family, classified as an immunologic adjuvant and sensitizing agent used to induce contact hypersensitivity and colitis models in mice.
Oxepane
Oxepane, also known as hexamethylene oxide or oxacycloheptane, is a saturated seven-membered cyclic ether with formula C₆H₁₂O; its ring is harder to synthesize than six-membered ethers and appears in natural products including artemisinin.
Oxepanoprolinamide
Oxepanoprolinamides are a class of fully synthetic antibiotics developed in Andrew Myers's Harvard laboratory from the lincosamide clindamycin, first reported in 2021; its lead compound iboxamycin and later cresomycin stay active against bacteria resistant to clindamycin.
Oxetane
Oxetane, also called oxacyclobutane or trimethylene oxide, is a strained four-membered cyclic ether (C₃H₆O) first synthesized in the 1870s and widely used in medicinal chemistry.
Oxford Clay
The Oxford Clay Formation is a Jurassic mudstone rock unit of southern and eastern England, a major source of brickmaking clay and of exceptionally preserved marine fossils.
Oxford Electric Bell
The Oxford Electric Bell, also called the Clarendon Dry Pile, is an experimental electric bell at Oxford's Clarendon Laboratory that has rung almost continuously since 1840 on batteries never replaced.