All articles starting with P
28,818 articles
Polytene chromosome
Polytene chromosomes are giant interphase chromosomes of dipteran larvae formed by endoreduplication, with 1024+ aligned strands, banded structure, puffs of gene activity, and classic use in cytogenetic mapping.
Polytetrafluoroethylene
Polytetrafluoroethylene (PTFE), sold as Teflon, is a slippery, chemically resistant fluoropolymer discovered accidentally by Roy Plunkett at DuPont in 1938, best known as the nonstick coating on cookware.
Polytetrafluoroethylene binder
The polytetrafluoroethylene (PTFE) binder is a fluoropolymer used in dry battery electrode processing, where mechanical shear turns PTFE particles into a fibrous, solvent-free binding network.
Polytetramethylene ether glycol
Polytetramethylene ether glycol (PTMEG), also called polytetrahydrofuran or PTHF, is a linear polyether diol made from tetrahydrofuran, used mainly to make spandex fibers and polyurethane elastomers.
Polytheism
Polytheism is the belief in or worship of multiple divine beings, a term of Greek origin describing traditions such as those of ancient Greece, Egypt, Mesopotamia, and Rome, and living religions like Hinduism and Shinto.
Polythiazide
Polythiazide (Renese) is a long-acting thiazide diuretic developed by Pfizer, FDA-approved September 26, 1961 as a new molecular entity in 1-4 mg oral tablets, about 250 times as potent as chlorothiazide, now discontinued.
Polythiophene
Polythiophene is a conjugated conducting polymer of linked thiophene rings that is semiconducting when neutral and conductive when doped, first well-defined synthesis reported in 1980.
Polytope
A polytope is a geometric object bounded by lines, planes, or hyperplanes: a polygon in two dimensions, a polyhedron in three, and a bounded region of n-dimensional space in general.
Polytrichum
Polytrichum (hair-cap mosses) is the type genus of Polytrichaceae mosses, with sheathing-blade leaves bearing photosynthetic lamellae, internal hydrome/leptome conducting strands, 64-toothed peristomes on an epiphragm, and a Late Cretaceous fossil record.
Polytrichum commune
Polytrichum commune (common haircap moss), a large acrocarpous moss of Polytrichaceae with vertical photosynthetic leaf lamellae, hydrom-leptom conducting tissue, 4-angled capsules, and Northern Hemisphere temperate-boreal distribution.
Polytrichum juniperinum
Polytrichum juniperinum (juniper haircap moss), family Polytrichaceae: a cosmopolitan acrocarpous moss of dry acidic sites and burned soils, with entire leaf margins, 64-toothed capsules, and dioecious reproduction.
Polytron (electronics company)
Polytron is an Indonesian consumer electronics brand made by PT Hartono Istana Teknologi, founded in 1975 in Kudus, Central Java, known for televisions, audio, and electric vehicles.
Polytrope
A polytrope, also known as a polytropic fluid, is a model of a self-gravitating fluid sphere where pressure follows a power law of density, solved through the Lane–Emden equation.
Polyubiquitin chain
A polyubiquitin chain is a polymer of ubiquitin proteins linked through one of eight amino groups, forming a molecular code: K48 chains mark proteins for proteasomal degradation, K63 chains mediate signaling.
Polyunsaturated fat
Polyunsaturated fat, or PUFA, is dietary fat whose fatty acids contain two or more carbon–carbon double bonds, so it tends to be liquid at room temperature; linoleic and alpha-linolenic acids are essential.
Polyurea
Polyurea, also called polycarbamide, is a polymer with urea linkages in its backbone, made from isocyanates and amines, used as a spray-applied elastomer coating for waterproofing, corrosion protection, and blast mitigation.
Polyurethane
Polyurethane (PU) is a versatile polymer containing urethane linkages, first synthesized by Otto Bayer in 1937 and produced today as foams, elastomers, coatings, adhesives, and sealants.
Polyurethane adhesive
A polyurethane adhesive is an adhesive made from polyurethane polymers, formed by reacting isocyanates with polyols, and chosen where flexible bonds between dissimilar materials matter more than stiffness.
Polyurethane coating
A polyurethane coating is a protective surface film of polyurethane polymers applied to wood, metal, concrete, and other substrates, widely used in aerospace and automotive refinish.
Polyurethane foam
Polyurethane foam is a cellular thermoset polymer made by reacting isocyanates with polyols, used as rigid building insulation, spray foam, and flexible cushioning in furniture, bedding, and car seats.
Polyurethane recycling
Polyurethane recycling is the recovery of material value from waste polyurethane, a cross-linked thermoset that cannot be remelted, using mechanical regrinding or chemical depolymerization such as glycolysis.
Polyuria
Polyuria: excessive urine production, over 3 L/day in adults or 2 L/m² in children. Also called excessive urination; distinguished from urinary frequency and nocturia; caused by water diuresis (diabetes insipidus, primary polydipsia) or osmotic diuresis (hyperglycemia).
Polyus (Полюс) (spacecraft)
Polyus, also designated Skif-DM, was a Soviet experimental spacecraft launched on May 15, 1987 as the payload of the Energia rocket's maiden flight; a guidance failure prevented orbital insertion.
Polyvagal theory
Polyvagal theory, proposed by Stephen Porges in 1995, links vagal brainstem nuclei to social behavior and autonomic states; its physiological and evolutionary premises are contested by Grossman and other experts.
Polyvinyl acetate
Polyvinyl acetate (PVAc), sold as white or school glue, is a thermoplastic polymer made from vinyl acetate, used in wood and paper adhesives, latex paints, and chewing gum base.
Polyvinyl alcohol
Polyvinyl alcohol (PVA or PVOH) is a water-soluble, biodegradable synthetic polymer made by hydrolyzing polyvinyl acetate, used in textile sizing, paper coatings, and detergent films.
Polyvinyl butyral
Polyvinyl butyral (PVB), also known as Butacite, is a thermoplastic resin best known as the plastic interlayer bonding glass sheets in laminated safety glass, and also used in coatings, inks, and adhesives.
Polyvinyl chloride
Polyvinyl chloride (PVC), also called polychloroethene, is a synthetic thermoplastic polymer made by polymerizing vinyl chloride, used mainly in construction for pipes, windows, and flooring, with global production of 44.3 million tons in 2018.
Polyvinyl chloride recycling
Polyvinyl chloride recycling recovers waste PVC, the third most used thermoplastic, through mechanical, dissolution, or chemical routes; high chlorine content and legacy additives make it hard.
Polyvinyl ether
A polyvinyl ether is a polymer made from vinyl ether monomers, prepared almost exclusively by cationic polymerization, and used in adhesives, coatings, and pharmaceutical materials.