42,772 articles
Hot electron transfer
Hot electron transfer moves charge carriers carrying excess kinetic energy into an adjacent material or molecule before they cool, promising hot-carrier solar cells with up to 66% efficiency.
Hot Jupiter
A hot Jupiter is a gas-giant exoplanet like Jupiter orbiting very close to its star, with atmospheric temperatures in the thousands of degrees; 51 Pegasi b was the first found.
Hot Jupiter superrotation
Hot Jupiter superrotation is the atmospheric regime in which equatorial winds on tidally locked hot Jupiters exceed the planet's rotation, displacing the dayside hotspot eastward of the star-facing point.
Hot plate (laboratory)
A laboratory hot plate is a flat, electrically heated surface for heating flat-bottomed vessels like beakers and flasks, often built with a magnetic stirrer into one unit.
Hot spot analysis
Hot spot analysis is a spatial statistics method that identifies statistically significant clusters of high or low values in geographic data, most commonly with the Getis-Ord Gi statistic.
Hot-carrier cooling
Hot-carrier cooling is the process by which photoexcited electrons and holes lose excess energy to a semiconductor lattice by emitting phonons, typically within picoseconds; slow cooling in metal halide perovskites motivates hot-carrier solar cells.
Hot-carrier cooling bottleneck in halide perovskites
The hot-carrier cooling bottleneck in halide perovskites is the unusually slow cooling of photoexcited carriers, extending to tens of picoseconds versus femtoseconds in conventional semiconductors, attributed mainly to a hot-phonon bottleneck.
Hot-carrier extraction in perovskites
Hot-carrier extraction in perovskites collects photoexcited carriers before they lose excess energy as heat, a route toward solar cells exceeding the Shockley–Queisser limit, with extraction efficiencies up to about 80%.
Hot-carrier multiplication in graphene
Hot-carrier multiplication in graphene is an ultrafast many-particle process in which a single absorbed high-energy photon creates multiple charge carriers via Auger scattering, enabled by graphene's gapless, linear band structure.
Hot-injection synthesis
Hot-injection synthesis, or hot injection, is a nanocrystal preparation method in which precursors are rapidly injected into a hot ligand-containing solvent, giving monodisperse quantum dots.
Hot-injection synthesis of CsPbX3 perovskite nanocrystals
Hot-injection synthesis of CsPbX3 perovskite nanocrystals is a colloidal method, first reported in 2015 by Protesescu and co-workers, that makes color-tunable cesium lead halide nanocrystals used in displays.
Hot-phonon bottleneck in lead-halide perovskites
The hot-phonon bottleneck in lead-halide perovskites is a slowdown of hot-carrier cooling caused by reabsorbed hot optical phonons, discussed since 2015 as a route to hot-carrier solar cells.
Hot-spot ignition
Hot-spot ignition is the inertial confinement fusion scheme in which alpha-particle self-heating triggers a self-sustaining burn, first demonstrated at the National Ignition Facility in December 2022.
Hot-wire anemometry
Hot-wire anemometry is a technique for measuring fluid velocity in which an electrically heated fine wire is cooled by the flow, most often in the constant temperature mode.
Hot-wire method (thermal conductivity)
The hot-wire method is a transient technique for measuring thermal conductivity, in which a thin electrically heated wire embedded in the material acts as a line heat source.
Hot, dust-obscured galaxy
A hot, dust-obscured galaxy (Hot DOG) is a rare hyperluminous infrared galaxy discovered by the WISE satellite and powered by a heavily obscured, extremely luminous active galactic nucleus.
Hotelling's T-squared distribution
Hotelling's T-squared distribution is the sampling distribution of a statistic measuring a multivariate sample mean's squared distance from a hypothesized value, introduced by Harold Hotelling in 1931.
Hotspot (geology)
A hotspot is a volcanic region, usually far from plate boundaries, where magma rises from a fixed source, leaving trails of volcanoes like Hawaii, Iceland, and Yellowstone.
Houben-Weyl Methods of Organic Chemistry
Houben-Weyl Methods of Organic Chemistry, or Methoden der Organischen Chemie, is a multivolume German reference work on preparative organic chemistry published by Georg Thieme Verlag from 1909 to 2003.
Hour
The hour is a unit of time equal to 60 minutes, or 3600 seconds, conventionally one twenty-fourth of a day, and a non-SI unit accepted for use with the SI.
Hourglass
An hourglass, also called a sand timer or sand clock, is a timekeeping device in which sand falls through a narrow neck between two glass bulbs to mark a fixed interval.
Hourglass fermions
Hourglass fermions are quasiparticle excitations whose surface bands form an hourglass shape, protected by nonsymmorphic crystal symmetries and first proposed in 2016 in KHgSb family materials.
Household income in the United States
Household income in the United States, also called U.S. household income, is the combined income of all people in a housing unit, measured chiefly by the Census Bureau's surveys.
Household, Income and Labour Dynamics in Australia
The Household, Income and Labour Dynamics in Australia (HILDA) Survey, known to respondents as the Living in Australia Study, has tracked Australian households annually since 2001.
Householder transformation
The Householder transformation, also called a Householder reflection, is a symmetric orthogonal matrix reflecting vectors across a hyperplane, widely used in QR factorization since Alston Householder introduced it in 1958.
How to Solve It
How to Solve It is a 1945 book by the Hungarian mathematician George Pólya setting out a four-phase method for solving problems and a collection of heuristics.
Howard Allan Zebker
Howard Allan Zebker is an American electrical engineer and geophysicist at Stanford University, a pioneer of interferometric synthetic aperture radar elected to the National Academy of Engineering in 2024.
Howard Bishop Lewis
Howard Bishop Lewis (1887–1954) was an American biochemist who headed biological chemistry at the University of Michigan and was elected to the National Academy of Sciences in 1949.
Howard Ensign Simmons, Jr.
Howard Ensign Simmons, Jr. (1929–1997) was an American physical organic chemist at DuPont whose diiodomethane-zinc work produced the Simmons–Smith reaction, the first general cyclopropane synthesis.
Howard Georgi
Howard Georgi is an American theoretical particle physicist and Harvard professor, best known as a founder of grand unified theories and inventor of the Heavy Quark Effective Theory.