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Endothelin-1
Endothelin-1 (ET-1) is a 21-amino acid peptide produced chiefly by vascular endothelial cells and one of the most potent vasoconstrictors, isolated in 1988 in Japan.
Endothermic process
An endothermic process, also called an endothermic reaction or endoergic, is a physical or chemical change that absorbs heat from its surroundings, giving a positive enthalpy change.
Endre Szemerédi
Endre Szemerédi, born 1940 in Budapest, is a Hungarian mathematician and computer scientist at Rutgers whose 1975 proof of Szemerédi's theorem won the 2012 Abel Prize.
Ene reaction
The ene reaction, also called the Alder ene reaction, is an organic addition reaction between an alkene with an allylic hydrogen and an enophile, related to the Diels–Alder reaction.
Energetic particle mode
An energetic particle mode is a plasma instability in fusion devices whose frequency and structure are set by energetic particles rather than by the bulk plasma.
Energetic-particle-driven Alfvénic modes
Energetic-particle-driven Alfvénic modes are magnetohydrodynamic oscillations of confined fusion plasmas, destabilized by fast ions resonating with Alfvén waves, sometimes expelling over 50% of beam power.
Energy
Energy is the physical quantity measuring a system's ability to do work; it appears in forms like kinetic, thermal, and chemical, and is never created or destroyed.
Energy cascade
The energy cascade is the transfer of kinetic energy across scales in a turbulent flow, from large eddies down through smaller ones until viscosity dissipates it as heat.
Energy conditions (general relativity)
In general relativity, energy conditions are inequalities on the stress-energy tensor prescribing positive energy density and gravity's attractiveness, best known from Penrose and Hawking singularity theorems.
Energy confinement time and scaling laws
Energy confinement time is the ratio of stored thermal energy to heating power in a magnetically confined plasma, with empirical scaling laws predicting confinement across tokamak sizes.
Energy decomposition analysis
Energy decomposition analysis is a computational chemistry method that splits the interaction energy between molecules into components such as electrostatics, Pauli repulsion, polarization, and charge transfer.
Energy density
Energy density, also called fuel value, is the amount of energy stored in a system per unit volume, measured in joules per cubic meter; for fuels and batteries it is reported as watt-hours per liter.
Energy filtering (electron microscopy)
Energy filtering, known as energy-filtered TEM (EFTEM), is a transmission electron microscopy technique that removes inelastically scattered electrons or uses them to form elemental maps.
Energy Information Administration
The U.S. Energy Information Administration (EIA), established in 1977, is the independent statistical agency of the Department of Energy, collecting and publishing energy data for the public.
Energy level
An energy level, also called an energy state, is one of the allowed values of the total energy of a quantum system such as an atom or molecule.
Energy method
The energy method is a technique in the analysis of partial differential equations in which an estimate for a nonnegative quantity, called an energy, is derived from the equation itself.
Energy minimization
Energy minimization, also called geometry optimization, is the computational search for a local minimum of potential energy on a potential energy surface, using algorithms such as L-BFGS.
Energy profile (chemistry)
An energy profile is a chemistry diagram of the relative energies of reactants, transition states, intermediates, and products, with peak heights giving the activation energies that determine a reaction's rate.
Energy recovery linac
An energy recovery linac (ERL) is a linear particle accelerator whose spent electron beam is decelerated in the same cavities that accelerated it, recovering most of its energy for reuse.
Energy release rate
The energy release rate, usually written G, is a fracture mechanics quantity measuring the energy released per unit of new crack surface as a crack extends.
Energy transformation
Energy transformation, also called energy conversion, is the process by which energy changes from one form into another, such as chemical energy becoming mechanical energy in a car engine.
Energy-dispersive X-ray diffraction
Energy-dispersive X-ray diffraction, also called white-beam XRD, is a technique in which a polychromatic X-ray beam and energy-discriminating detector record diffraction patterns at a fixed angle, suited to time-resolved and bulk studies.
Energy-dispersive X-ray fluorescence
Energy-dispersive X-ray fluorescence (EDXRF) is an elemental analysis technique that excites a sample with X rays and identifies its elements from their emitted X-ray energies.
Energy-dispersive X-ray spectroscopy
Energy-dispersive X-ray spectroscopy, also called EDX or EDS, identifies the elemental composition of a sample by measuring characteristic X-rays emitted under a focused electron beam.
Energy-filtered transmission electron microscopy
Energy-filtered transmission electron microscopy, also called electron spectroscopic imaging, is a TEM technique that images electrons of a chosen energy loss to map specific elements at better than 1 nm resolution.
Energy-loss near-edge structure
Energy-loss near-edge structure (ELNES) is the fine structure on EELS ionization edges within about 50 eV of the edge onset, reporting an atom's bonding environment and oxidation state.
Energy-transfer [2+2] cycloaddition
Energy-transfer [2+2] cycloaddition is a photochemical reaction in which a visible-light photocatalyst transfers triplet energy to an alkene, allowing the otherwise UV-only, thermally forbidden formation of cyclobutanes.
Energy–momentum relation
The energy–momentum relation, also called the relativistic energy–momentum equation, is the special relativity formula E² = (pc)² + (mc²)² connecting a particle's energy, momentum, and rest mass.
Energy–time uncertainty relation
The energy–time uncertainty relation is a set of inequalities in quantum mechanics connecting energy spread to lifetimes and evolution times, with no time operator involved.
Engine braking
Engine braking, also called compression braking, is the slowing of a vehicle by using its engine, kept in gear, to absorb momentum instead of providing power.