All articles starting with P

Polysaccharide

Polysaccharide (glycan): long carbohydrate polymer of >10 monosaccharide residues joined by glycosidic linkages; homoglycans vs heteroglycans; includes starch, glycogen, cellulose, chitin, pectin; about two-thirds of biomass dry weight.

Oct 20, 2026

Polysaccharide lyase

Polysaccharide lyases (PLs, EC 4.2.2.-) are CAZy-classified enzymes that cleave uronic acid-containing polysaccharides such as pectin, alginate, and heparin by β-elimination, via metal-assisted or Tyr/His mechanisms, in dozens of sequence families.

Polysemanticity

Polysemanticity is the phenomenon in which a single neuron in a trained neural network activates in multiple unrelated contexts; the leading explanation is superposition, and sparse autoencoders are the main remedy.

Polysemy

Polysemy: a single word form with multiple related senses (paper, chicken), coined by Michel Bréal in 1897; distinguished from homonymy (bank, bark) by semantic relatedness, with distinct processing and representation signatures.

PolySign, Inc.

PolySign, Inc. is an Oakland, California financial technology company founded in 2017 that built blockchain-based digital-asset custody and infrastructure for institutional investors, raising over $183 million.

Polysius

Polysius is a German cement plant engineering company founded in 1859 in Dessau, now thyssenkrupp Polysius GmbH in Beckum, known for its rotary kiln, the Lepol kiln, and cement decarbonization technologies.

Polysomnography

Polysomnography (PSG), the overnight sleep study, records EEG, EOG, EMG, breathing, oxygen, and heart activity to diagnose sleep apnea, narcolepsy, and parasomnias; term coined 1974.

Polysorbate 20

Polysorbate 20, or Polyoxyethylene sorbitan monolaurate, is a synthetic nonionic surfactant used as a stabilizer in parenteral biologic drug products, with a WHO accepted daily intake of 25 mg/kg.

Polysorbate 60

Polysorbate 60, known commercially as Tween 60, is a synthetic nonionic surfactant called polyoxyethylene (20) sorbitan monostearate, serving as an emulsifier and stabilizer in foods, cosmetics, and pharmaceuticals.

Polysorbate 80

Polysorbate 80, also sold as Tween 80, is a nonionic surfactant and emulsifier used in foods, cosmetics, medicines, and vaccines, and to stabilize protein biopharmaceuticals.

Polyspermy

Polyspermy is fertilization of an egg by multiple sperm, causing lethal polyploidy. Blocks include the fast electrical depolarization in sea urchins and the slow cortical reaction; mammals use zona pellucida and membrane blocks instead.

Oct 20, 2026

Polysplenia

Polysplenia, also called left isomerism or heterotaxy with left atrial isomerism, is a rare congenital condition of 2 to 15 spleens with midline liver, intestinal malrotation, interrupted IVC, and less severe heart disease than asplenia.

Polystachya

Polystachya Hook. (yellowspike orchid) is a conserved pantropical orchid genus of about 240-250 epiphytic, lithophytic, or terrestrial species, richest in Africa, with pseudopollen food hairs instead of nectar and a non-monophyletic Polystachya concreta complex.

Polystichum

Polystichum (hollyfern, shield fern) is a cosmopolitan fern genus of Dryopteridaceae with roughly 400-500 species, evergreen fronds, and single-row sori with peltate indusia; most diverse in East Asia.

Polystichum acrostichoides

Polystichum acrostichoides, the Christmas fern, is an evergreen Dryopteridaceae fern native from eastern Canada to northeastern Mexico. Dimorphic fronds, winter leaf prostration, spores June–October, common shade-garden ornamental.

Polystichum munitum

Polystichum munitum, western swordfern, is an evergreen Dryopteridaceae fern of Pacific Coast forests from Alaska to Baja California, with 0.3-1.2 m toothed fronds, single-row sori, and close relation to P. imbricans.

Polystictus

Polystictus is a genus of tyrant flycatchers (Tyrannidae) erected by Reichenbach in 1850 with two grassland species, the migratory Near Threatened Bearded Tachuri and the Grey-backed Tachuri; the same name also denotes a fungal genus now merged into Coltricia.

Polystoma integerrimum

Polystoma integerrimum (Frölich, 1791) is a monogenean flatworm, family Polystomatidae, parasitizing the urinary bladder of Rana temporaria; known for its dimorphic life cycle with neotenic gill-dwelling adults bearing 2 suckers versus 6-suckered bladder adults.

Polystyrene

Polystyrene, also known as Polystyrol or Thermocol, is a synthetic thermoplastic polymer of styrene, first prepared in 1839 and one of the most widely used plastics.

Polystyrene depolymerization

Polystyrene depolymerization chemically breaks down the polystyrene chain into styrene monomer or value-added chemicals such as benzoic acid and toluene, the core operation of polystyrene chemical recycling.

Polystyrene latex spheres

Polystyrene latex (PSL) spheres are highly spherical polymer particles in water, made in narrow size distributions and used to calibrate instruments that measure particle size.

Polystyrene recycling

Polystyrene recycling is the recovery of waste polystyrene, including expanded foam packaging, through mechanical reprocessing, pyrolysis back to styrene monomer, or upcycling, though low collection economics keep rates low.

Polystyrene sulfonate

Polystyrene sulfonate is a non-absorbed cation-exchange resin, sold as Kayexalate and Kionex, used to treat hyperkalemia by exchanging sodium for potassium in the gut; approved by the FDA in 1958.

Polystyrene upcycling

Polystyrene upcycling is the conversion of waste polystyrene into higher-value products, covering chemical upcycling into chemicals like benzoic acid and styrene monomer, and physical upcycling that improves recycled material, in contrast to downcycling.

Polysulfide shuttle suppression

Polysulfide shuttle suppression is the set of materials and design strategies that stop soluble lithium polysulfides from migrating between cathode and anode in lithium–sulfur batteries.

Polysulfone

Polysulfone is an amorphous, transparent engineering thermoplastic with a bisphenol A backbone, first commercialized in 1965 and best known for separation membranes in hemodialysis and water treatment.

Polysyndactyly

Polysyndactyly (PPD4, OMIM 174700, ORPHA93338) is a rare autosomal dominant limb malformation with mild thumb duplication and digit webbing, linked to GLI3 at 7p14.1, distinct from synpolydactyly and Haas type polysyndactyly.

Polysyndactyly-cardiac malformation syndrome

Polysyndactyly-cardiac malformation syndrome, or Bonneau syndrome (OMIM 263630), is an extremely rare autosomal recessive disorder combining polysyndactyly with complex congenital heart defects; usually fatal in utero or infancy, with about nine reported cases.

Polytechnic University of Turin

Politecnico di Torino (Polytechnic University of Turin, PoliTo), public Italian technical university founded 1906 from the 1859 School for Engineers; engineering, architecture, design; ~38,700 students; QS 206th in 2027.