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Oceanic plateau
An oceanic plateau is a vast region of anomalously thick oceanic crust, typically over 200,000 km² in area, formed by mantle plumes; the largest is the Ontong Java Plateau.
Oceanographer
An oceanographer is a scientist who studies the ocean, including its processes, seawater, seafloor, and marine life. The field divides into biological, chemical, geological, and physical branches.
Oceanographic time-series cruise programs
Oceanographic time-series cruise programs are recurring shipboard expeditions that occupy the same deep-ocean station on a monthly schedule to measure water-column physics, chemistry, and biology over decades.
Oceanography
Oceanography, also called ocean science or marine science, is the study of the ocean, drawing on physics, chemistry, geology, and biology to cover seawater, marine life, currents, and the seafloor.
Ochre
Ochre is an earthy rock rich in iron oxides, often mixed with clay, that can be ground into red, yellow, or brown pigment; humans have used it for at least 300,000 years.
Ocimene
Ocimene is an acyclic monoterpene hydrocarbon found in the essential oils of many plants, including basil, hops, and bay, and it occurs as several geometric isomers.
Octabromodiphenyl ether
Octabromodiphenyl ether, also known as octaBDE or octabromodiphenyl oxide, is a brominated flame retardant used in ABS plastic electronics housings and phased out of production in 2004.
Octadecane
Octadecane, also called n-octadecane, is a straight-chain alkane with formula C₁₈H₃₈ that melts near 28 °C and is widely used as a phase change material.
Octadecylamine
Octadecylamine, also called stearylamine or 1-octadecanamine, is a white, waxy 18-carbon primary aliphatic amine (C₁₈H₃₉N) used as a film-forming corrosion inhibitor for steam systems and as a building block for cationic surfactants.
Octadecyltrichlorosilane
Octadecyltrichlorosilane (OTS) is a long-chain organosilane, CH₃(CH₂)₁₇SiCl₃, best known for forming self-assembled monolayers on glass, silicon dioxide, and mica, and used for water-repellent coatings and surface patterning.
Octagon
An octagon is a polygon with eight sides and eight angles; a regular octagon has 135° interior angles and is the shape of the stop sign.
Octahedral molecular geometry
Octahedral molecular geometry is the arrangement of six atoms or ligands around a central atom at the corners of an octahedron, with 90° bond angles, as in sulfur hexafluoride.
Octahedral Pt–Ni oxygen-reduction nanocatalysts
Octahedral Pt–Ni oxygen-reduction nanocatalysts are octahedral platinum–nickel alloy nanoparticles whose {111} facets give high oxygen reduction activity, developed to cut platinum use in fuel cells.
Octahedron
An octahedron, also called a square bipyramid, is a polyhedron with eight triangular faces, six vertices, and 12 edges; the regular form is one of the five Platonic solids.
Octal
Octal, also known as base 8, is the numeral system using the digits 0 through 7, where each digit corresponds to three binary bits, used in Unix file permissions.
Octamethylcyclotetrasiloxane
Octamethylcyclotetrasiloxane (D4) is a cyclic volatile methylsiloxane, a colorless liquid produced from dimethyldichlorosilane and used chiefly as a monomer for silicone polymers; it is now restricted in the EU.
Octamethylenediamine
Octamethylenediamine, also called 1,8-diaminooctane or 1,8-octanediamine, is an eight-carbon aliphatic diamine, H2N(CH2)8NH2, used as a monomer in nylon synthesis and as the main polyamine in the fungicide guazatine.
Octanal
Octanal, also known as caprylic aldehyde, is a saturated straight-chain aliphatic aldehyde, C8H16O, that occurs naturally in citrus oils and is used widely as a flavoring and fragrance ingredient.
Octane
Octane is a colorless, flammable alkane hydrocarbon with the molecular formula C8H18, occurring in crude oil and natural gas; its 18 isomers include n-octane and isooctane, the anchor of the gasoline octane rating.
Octanitrocubane
Octanitrocubane is a powerful organic explosive with a nitro group on each carbon of a cubane cage, first synthesized in 2000 by Philip Eaton and Mao-Xi Zhang in Chicago.
Octanoate
Octanoate is the anion, salts, and esters of octanoic acid (caprylic acid), an eight-carbon saturated fatty acid occurring in milk, palm oil, and coconut oil, and used in IVIG purification.
Octans
Octans is a faint southern constellation, created by Nicolas Louis de Lacaille in the 1750s, that contains the south celestial pole and its dim pole star Sigma Octantis.
Octet (computing)
An octet is a group of exactly eight bits, a unit of data used especially in network protocol specifications, where byte is avoided because some systems historically used bytes of other sizes.
Octet rule
The octet rule, also called the Lewis–Langmuir theory, is a chemistry rule of thumb stating that main-group atoms tend to bond to reach eight valence electrons, a noble-gas configuration.
October 2010 Sumatra earthquake
The October 2010 Sumatra earthquake was a magnitude 7.8 thrust quake off the Mentawai Islands, west of Sumatra, on 25 October 2010; its tsunami killed several hundred people.
October 2021 Northeast Pacific bomb cyclone
The October 2021 Northeast Pacific bomb cyclone was an explosively deepening extratropical cyclone that struck the Pacific Northwest on October 24, 2021, reaching a record-low pressure of 942.5 mb.
Octonion
Octonions, also known as Cayley numbers, form an 8-dimensional normed division algebra over the real numbers, described by John Graves in 1843 and published by Arthur Cayley in 1845.
Octonions
The octonions, also known as Cayley numbers or octaves, are an eight-dimensional number system whose multiplication is neither commutative nor associative, the largest of the four normed division algebras.
Octopamine
Octopamine is a biogenic amine, first found in octopus salivary glands in 1948, that serves as a neurotransmitter and neurohormone in invertebrates, regulates insect behavior, and occurs as a trace amine in mammals.
Octopus (software)
Octopus is a free, open-source scientific code, first described in 2006, that uses time-dependent density-functional theory to simulate electron and ion dynamics in finite systems responding to electromagnetic fields.