All articles starting with P

Pyrenees

The Pyrenees (Pirineos, els Pirineus, Pyrénées) are a 430-km mountain range forming the France–Spain–Andorra border, uplifted by the Alpine orogeny, with over 3,000-m summits, rapidly vanishing glaciers, and the Pyrénées–Mont Perdu World Heritage site.

Pyrénées - Mont Perdu

Pyrénées - Mont Perdu (Monte Perdido), a UNESCO mixed World Heritage site (1997) of 30,639 ha on the Franco-Spanish border, centred on the 3,348-3,352 m limestone Mont Perdu, with Spanish canyons, French cirques, and living transhumance.

Pyrenees Oil and Gas Field

The Pyrenees Oil and Gas Field is a group of six offshore oil fields about 45 km northwest of Exmouth, Western Australia, producing since 2010.

Pyrénées-Orientales

Pyrénées-Orientales (Catalan: Pirineus Orientals), French department 66, prefecture Perpignan; also called Roussillon or Catalunya Nord. Created 1790 from the province ceded by the 1659 Treaty of the Pyrenees plus the Fenouillèdes; 484,215 residents (2018), tourism-led economy.

Pyrethrin

Pyrethrins: six natural insecticidal esters from pyrethrum chrysanthemum flowers, sodium-channel axonic poisons with rapid knockdown, low mammalian toxicity, high fish and bee toxicity; basis of synthetic pyrethroids.

Pyrethroid

A pyrethroid is a synthetic insecticide modeled on the pyrethrins of chrysanthemum flowers, acting on insect nerves and widely used in agriculture and mosquito control.

Pyrethrum

Pyrethrum, from Chrysanthemum cinerariaefolium (Tanacetum cinerariifolium), is powdered dried pyrethrum daisy flowers containing six insecticidal esters called pyrethrins; sodium-channel neurotoxins of low mammalian toxicity, distinct from synthetic pyrethroids and central to Kenya's pyrethrum industry.

Pyrex

Pyrex, or Pyrex glass, is a heat-resistant glassware brand introduced in 1915 by Corning Glass Works of Corning, New York, known for borosilicate laboratory glass and American bakeware.

Sep 19, 2026

Pyrgi tablets

The Pyrgi tablets, also called the Pyrgi gold plates, are three gold plates from about 500 BC recording a dedication by Thefarie Velianas of Caere to the goddess Astarte.

Pyrgomorphidae

Pyrgomorphidae, gaudy or bush grasshoppers (Orthoptera: Caelifera, Pyrgomorphoidea), a colorful family of about 500 aposematic species, mostly Old World tropical, with Zonocerus as an African crop pest.

Pyrgos (Greece)

Pyrgos (Πύργος), Greek for "tower": the Elis regional capital with its Archaeological Museum, the Minoan site of Pyrgos-Myrtos in Crete, and ancient and Ottoman towers in Argolis, Thesprotia, and Chalkidiki.

Pyrgos Kheimarrou

Pyrgos Kheimarrou (Πύργος Χειμάρρου), Tower of Cheimarros: circular 4th-century BC Hellenistic marble tower in southeastern Naxos, Cyclades, 9.20 m in diameter, with a 35 m square enclosure, Hellenistic and Roman agricultural workshops, and debated military or signal-fire function.

Pyrgos, Elis

Pyrgos (Πύργος), capital of the Elis regional unit in the Western Peloponnese, Greece; named for a 1512 tower, port Katakolo, 19 km from Ancient Olympia; municipality formed 2011, population about 25,600.

Pyrgulifera

Pyrgulifera (Meek, 1871) is an extinct cerithioidean gastropod genus, placed in Thiaridae or Hemisinidae, from Cretaceous to Eocene freshwater and brackish deposits of Europe, North America, Asia, and Oceania.

Pyrgulopsis

Pyrgulopsis (springsnails) is a genus of tiny hydrobiid freshwater snails of western North America, with about 150 mostly single-spring endemic species; gilled, operculate algae grazers with imperilment rates up to 92 percent.

Pyridaben

Pyridaben (Sanmite, Nexter) is a pyridazinone METI acaricide, IRAC group 21A, inhibiting mitochondrial Complex I. Developed by Nissan Chemical, registered in Japan in 1991, used against mites, whiteflies, aphids, and thrips.

Pyridafol

Pyridafol (CL 9673), 6-chloro-3-phenylpyridazin-4-ol, is a phenylpyridazine photosystem II inhibitor herbicide and the main hydrolysis product and metabolite of pyridate; not EU-approved, regulated as pyridate residues.

Oct 20, 2026

Pyridalyl

Pyridalyl (S-1812, Pleo) is a dihalopropene-class insecticide from Sumitomo Chemical, first launched in South Korea in 2004, active against lepidopteran and thrips pests, selectively toxic to insect cells, persistent and highly bioaccumulative in the environment.

Pyridate

Pyridate (CAS 55512-33-9) is a Group 6 photosystem II-inhibiting contact herbicide for emerged broadleaf weeds in corn, mint, canola, and other crops; first registered 1996, cancelled 2004, reregistered 2020.

Pyridazine

Pyridazine, also called 1,2-diazine or orthodiazine, is an aromatic six-membered heterocycle with the formula C4H4N2, two adjacent nitrogen atoms, and the highest dipole moment of the three diazine isomers.

Pyridine

Pyridine (C5H5N), also known as azabenzene, is a six-membered aromatic heterocycle and colorless liquid with a fish-like odor, used as a solvent, weak base, and chemical intermediate.

Oct 22, 2026

Pyridinic nitrogen edge-site ORR activity

Pyridinic nitrogen edge-site ORR activity is the catalytic behavior of pyridinic nitrogen at graphene edges in the oxygen reduction reaction, assigned as the active site in 2016.

Pyridinium chlorochromate

Pyridinium chlorochromate (PCC), also called the Corey–Suggs reagent, is a red-orange chromium(VI) salt that selectively oxidizes primary alcohols to aldehydes and secondary alcohols to ketones.

Pyridinoline

Pyridinoline, also called hydroxylysyl pyridinoline (HP), is a non-reducible trivalent collagen cross-link predominant in cartilage and bone; its structure was determined in 1978, and urinary pyridinoline serves as a biochemical marker of bone resorption.

Pyridostigmine

Pyridostigmine (Mestinon), pyridostigmine bromide, is an orally active reversible cholinesterase inhibitor approved in 1955; mainstay symptomatic treatment for myasthenia gravis, also soman nerve-agent pretreatment and off-label for orthostatic hypotension.

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.

Pyridoxal phosphate

Pyridoxal phosphate (PLP, pyridoxal 5′-phosphate) is the active coenzyme form of vitamin B6, serving over 140 EC-classified enzyme activities in transamination, decarboxylation, and related amino acid reactions via an external aldimine intermediate.

Pyridoxal phosphate biosynthesis

Pyridoxal phosphate biosynthesis produces PLP, the active form of vitamin B6 and cofactor for over 180 enzymes, through two unrelated de novo pathways, DXP-dependent and R5P, or salvage.

Pyridoxal phosphate in amino-group transfer

Pyridoxal phosphate, also known as pyridoxal 5′-phosphate, is the active form of vitamin B6 that serves as the coenzyme for amino-group transfer, or transamination, where amino acids exchange their amino groups with keto acids.