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Piezoelectricity
Piezoelectricity, also called the piezoelectric effect, is the ability of certain crystals to generate electric charge when mechanically stressed, first demonstrated by the Curie brothers in 1880.
Piezometer
A piezometer is an instrument or well that measures groundwater pressure at a specific point in the subsurface, commonly used to monitor seepage in dams.
Piezoresponse force microscopy
Piezoresponse force microscopy (PFM) is a scanning probe technique using a biased AFM tip to map piezoelectric and ferroelectric domains, detecting sub-picometer deformations with nanometer resolution.
Pig (猪) (zodiac)
The Pig (猪), also called the Year of the Pig or Year of the Boar, is the twelfth and final animal of the Chinese zodiac, paired with the Earthly Branch Hai.
Pigeonhole principle
The pigeonhole principle, also called the Dirichlet box principle, states that more than n objects placed in n boxes force one box to hold two or more.
Pigeonite
Pigeonite is a calcium-poor clinopyroxene mineral of magnesium, iron, and calcium, named in 1900 for Pigeon Point, Minnesota, and typical of rapidly cooled basaltic lavas.
Pigment
A pigment is a finely divided insoluble solid that colors a material by absorbing and scattering light, used mainly in paints, printing inks, and plastics and distinct from soluble dyes.
Pigpen cipher
The pigpen cipher, also called the masonic cipher, is a geometric substitution cipher that replaces letters with grid symbols, used by Freemasons since the 18th century.
PiHKAL
PiHKAL: A Chemical Love Story is a 1991 book by chemist Alexander Shulgin and Ann Shulgin, combining a fictionalized autobiography with a reference on 179 phenethylamines.
Pilar Ruiz-Lapuente
Pilar Ruiz-Lapuente is a Spanish astrophysicist at the University of Barcelona and CSIC who co-authored the 1998 discovery of the accelerating Universe and identified the companion star of Tycho's 1572 supernova.
Pilbara Minerals
Pilbara Minerals, since renamed PLS Group Limited, is an Australian lithium mining company whose Pilgangoora Operation in Western Australia supplies about 8 per cent of world lithium.
Pillars of Creation
The Pillars of Creation are tall columns of hydrogen gas and dust in the Eagle Nebula in Serpens, about 6,500 light-years from Earth, where new stars are forming.
Pillow lava
Pillow lava is fluid, usually basaltic lava that chills in contact with water and solidifies as rounded, pillow-shaped masses with glassy skins, forming most new ocean floor.
Pilot experiment
A pilot experiment, or pilot study, is a small-scale preliminary study that tests whether a study's methods and procedures are feasible before a larger definitive study is carried out.
Pilot wave theory
Pilot wave theory, also called the de Broglie–Bohm theory or Bohmian mechanics, is an interpretation of quantum mechanics in which particles have definite positions guided by a wave.
Pilot-wave hydrodynamics
Pilot-wave hydrodynamics is the field of fluid dynamics studying droplets that bounce on a vibrating liquid bath and walk across it, guided by their own waves.
Pimelic acid
Pimelic acid, also known as heptanedioic acid, is a seven-carbon saturated dicarboxylic acid with formula C7H12O4, serving as the precursor of biotin and a building block for polyamides.
Pimozide
Pimozide, brand name Orap, is an orally active first-generation antipsychotic of the diphenylbutylpiperidine class, used mainly for tic suppression in Tourette's disorder and known for prolonging the heart's QT interval.
Pinacidil
Pinacidil is a cyanoguanidine antihypertensive drug that opens ATP-sensitive potassium channels in vascular smooth muscle, developed by Leo Pharmaceutical Products and launched in Denmark in 1987 as Pindac.
Pinacol coupling reaction
The pinacol coupling reaction joins two aldehydes or ketones with a reductant to give a 1,2-diol, proceeding through ketyl radical anion intermediates and first reported by Rudolf Fittig in 1859.
Pinacol rearrangement
The pinacol rearrangement, also called the pinacol–pinacolone rearrangement, is the acid-catalyzed conversion of a 1,2-diol into a ketone or aldehyde, first observed by Rudolf Fittig in 1860.
Pinacolborane
Pinacolborane (HBpin), systematically named 4,4,5,5-tetramethyl-1,3,2-dioxaborolane, is a cyclic dialkoxyborane whose boron sits in a five-membered pinacol-derived ring, and is among the most widely used hydroborating and borylating reagents in modern organic synthesis.
Pincer-catalyst CO2 hydrogenation to methanol derivatives
Pincer-catalyst CO2 hydrogenation to methanol derivatives is a homogeneous catalytic route where ruthenium, manganese, and iron pincer complexes convert CO2-derived carbonates and formates to methanol.
Pindolol
Pindolol, sold as Visken, is a non-selective beta-blocker used mainly for high blood pressure, distinguished by intrinsic sympathomimetic activity, meaning it partly stimulates beta receptors while blocking them.
Pineapple Express
The Pineapple Express is an atmospheric river carrying tropical moisture from near Hawaii to the west coast of North America, bringing heavy rain and snow.
Piney Woods
The Piney Woods, also called the South Central Plains, is a temperate pine forest ecoregion covering East Texas, southern Arkansas, western Louisiana, and southeastern Oklahoma, and Texas's wettest natural region.
Ping Chang
Ping Chang is a climate and ocean scientist at Texas A&M University, where he holds the Louis & Elizabeth Scherck Chair in Oceanography and studies tropical climate variability and high-resolution Earth system prediction.
Ping Koy Lam
Ping Koy Lam (Lam Ping Koy) is an experimental physicist in quantum information and metrology, known for teleporting light fields, quantum key distribution, and co-founding QuintessenceLabs in 2006.
Pingualuit crater
Pingualuit crater, also known as Chubb Crater, is a meteorite impact crater in Ungava, northern Quebec, formed about 1.4 million years ago and filled by exceptionally pure Pingualuk Lake.
Pingyun Feng
Pingyun Feng is a materials chemist and Distinguished Professor at UC Riverside known for zeolite-analog cobalt phosphates and chalcogenide fast-ion conductors, winning the 2017 Cotton Award.