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Pyridoxal
Pyridoxal, one of the six forms of vitamin B6, is an aldehyde compound distinguished by its formyl group, and is the immediate precursor of the coenzyme pyridoxal 5′-phosphate.
Pyridoxamine
Pyridoxamine is one of the three naturally occurring forms of vitamin B6 and a transient intermediate in enzymatic transamination; as the drug Pyridorin, it inhibits advanced glycation end products.
Pyrilamine
Pyrilamine, also known as mepyramine, is a first-generation H1 antihistamine of the ethylenediamine class, introduced in 1944 and used today chiefly in creams for insect bites and stings.
Pyrimidine
Pyrimidine is an aromatic heterocyclic compound with a six-membered ring of four carbons and two nitrogens, the core of the DNA and RNA bases cytosine, thymine, and uracil.
Pyrimidine dimer
A pyrimidine dimer, also called a thymine dimer, is a DNA lesion in which ultraviolet light covalently joins two adjacent pyrimidine bases, most often two thymines, blocking replication.
Pyrimidinone
A pyrimidinone is a six-membered heterocyclic compound derived from pyrimidine in which one ring carbon carries a carbonyl group, widely used in medicinal chemistry in drugs such as lamivudine.
Pyrite
Pyrite, also called iron pyrite, is a common iron disulfide mineral (FeS₂) with a brass-yellow metallic luster nicknamed fool's gold; its oxidation causes acid mine drainage.
Pyrocatechuic acid
Pyrocatechuic acid, also called hypogallic acid or DHBA, is 2,3-dihydroxybenzoic acid, one of six dihydroxybenzoic acid isomers, occurring naturally in plants and formed in humans as a metabolite of aspirin.
Pyrochlore
Pyrochlore is a brown to black niobium oxide mineral with a cubic crystal structure, first described in Norway in 1826, and the world's primary source of niobium.
Pyrochlore iridates
Pyrochlore iridates are complex oxides with formula A₂Ir₂O₇, where rare-earth ions and iridium occupy a cubic pyrochlore structure, studied as quantum materials and oxygen evolution catalysts.
Pyrochlore quantum spin liquid
A pyrochlore quantum spin liquid is a proposed magnetic state where moments on the pyrochlore lattice of corner-sharing tetrahedra stay disordered yet quantum-entangled to the lowest temperatures.
Pyroclastic flow
A pyroclastic flow, also called a nuée ardente, is a hot, dense mixture of volcanic ash, rock fragments, and gas that races down a volcano's flanks at over 100 km/h.
Pyrocumulonimbus
A pyrocumulonimbus, or pyroCb, is a thunderstorm generated by wildfire heat, officially named flammagenitus, that injects smoke high into the atmosphere and spreads embers and lightning.
Pyroelectricity
Pyroelectricity, or the pyroelectric effect, is the property of certain polar crystals in which a temperature change generates electric charge on opposing faces, chiefly used in uncooled infrared detectors.
Pyrogallol
Pyrogallol, also called pyrogallic acid, is the simplest benzenetriol, a white solid prepared from gallic acid by Carl Wilhelm Scheele in 1786 and long used as a photographic developer and oxygen-absorbing reagent.
Pyroglutamic acid
Pyroglutamic acid, also called pidolic acid or 5-oxoproline, is the cyclic lactam of glutamic acid, an intermediate in glutathione metabolism and a common protein modification.
Pyrolusite
Pyrolusite is a manganese oxide mineral with formula MnO₂, the most stable polymorph of manganese dioxide and the principal ore of manganese, used to decolorize glass since antiquity.
Pyrolysis gas chromatography
Pyrolysis gas chromatography (Py-GC) is an analytical technique in which a sample is thermally decomposed in an inert atmosphere and its fragments are separated by gas chromatography.
Pyrolysis–gas chromatography–mass spectrometry
Pyrolysis–gas chromatography–mass spectrometry (Py-GC-MS) is an analytical technique that thermally decomposes a sample in an inert atmosphere, separating and identifying the volatile fragments by GC-MS.
Pyromellitic acid
Pyromellitic acid, or benzene-1,2,4,5-tetracarboxylic acid, is a tetracarboxylic acid with four carboxyl groups on a benzene ring, used in powder coatings and as a metal–organic framework linker.
Pyromellitic dianhydride
Pyromellitic dianhydride (PMDA) is the dianhydride of pyromellitic acid, a white hygroscopic crystalline solid made from durene and best known as the comonomer with 4,4′-oxydianiline in DuPont's Kapton polyimide film.
Pyrometer
A pyrometer, also called an optical pyrometer or radiation thermometer, is a non-contact instrument that measures temperature by detecting thermal radiation, letting it measure moving or very hot objects.
Pyrometry
Pyrometry is the measurement of a surface's temperature from its emitted thermal radiation without contact; pyrometers infer temperature from radiance using Planck's or the Stefan–Boltzmann law.
Pyrope
Pyrope is the magnesium-aluminum garnet, a blood-red gem mineral from mantle rocks such as kimberlite, known in the jewelry trade as the classic Bohemian garnet.
Pyrophoricity
Pyrophoricity is the chemical property of a material that ignites spontaneously in air without an ignition source at or below 54.4 °C (130 °F), even in small quantities.
Pyrophosphate
Pyrophosphate (inorganic pyrophosphate, PPi, diphosphate) is the anion of pyrophosphoric acid, formed in cells by ATP hydrolysis and a key endogenous inhibitor of hydroxyapatite mineralization.
Pyrophyllite
Pyrophyllite is a soft hydrous aluminum silicate mineral with the formula Al2Si4O10(OH)2, similar to talc, named in 1829 for exfoliating into fan shapes when heated, and mined chiefly for refractories and ceramics.
Pyrotinib maleate (Irene)
Pyrotinib maleate (Irene, 马来酸吡咯替尼) is Hengrui's oral irreversible HER1/HER2/HER4 kinase inhibitor, approved in China in 2018 for HER2-positive metastatic breast cancer, with phase III PFS gains in PHOEBE and PHILA.
Pyroxene
Pyroxene is the name of a group of dark rock-forming chain silicate minerals with formula XYZ₂O₆, abundant in igneous and metamorphic rocks and important in the Earth's upper mantle.
Pyrrhotite
Pyrrhotite is a non-stoichiometric iron sulfide mineral, Fe₁₋ₓS, whose iron vacancies make it magnetic; it is abundant in the crust and common in nickel and copper ores.