All articles starting with H
20,046 articles
Hydrodynamic electron flow in graphene
Hydrodynamic electron flow in graphene is a transport regime in which electrons collide with one another more often than with impurities, flowing collectively like a viscous fluid.
Hydrodynamic interaction
Hydrodynamic interaction is the influence suspended particles in a viscous fluid exert on each other's motion through their generated flows, central to sedimentation, colloidal suspensions, and microrheology.
Hydrodynamic lubrication
Hydrodynamic lubrication is a regime in which a fluid film drawn between two moving surfaces fully separates them and carries the load, with a friction coefficient below 0.01.
Hydrodynamic stability
Hydrodynamic stability is the branch of fluid mechanics that studies whether laminar flows remain laminar under small disturbances or transition to turbulence, using tools like the Orr-Sommerfeld equation.
Hydroelectric power in India
Hydroelectric power in India is electricity generated from the country's rivers, supplying about 10% of installed capacity with roughly 49,600 MW of large hydro in 2025.
Hydroelectricity
Hydroelectricity, also called hydroelectric power, is electricity generated from moving or falling water; it supplies about 14% of the world's electricity, the most of any renewable source.
Hydroelectricity in Turkey
Hydroelectricity in Turkey, also called hydropower in Turkey, is generated at more than 770 plants with about 32,200 MW installed capacity, the country's largest power resource.
Hydrofining
Hydrofining is a petroleum refining hydrotreating process in which distillates are treated with hydrogen over a catalyst to remove sulfur and nitrogen, first used commercially in the 1950s.
Hydroflumethiazide
Hydroflumethiazide (Saluron, Diucardin) is an oral thiazide diuretic and antihypertensive benzothiadiazine, C8H8F3N3O4S2, inhibiting the SLC12A3 sodium-chloride symporter; discontinued in the US.
Hydrofluoric acid
Hydrofluoric acid (HF) is a solution of hydrogen fluoride in water, a weak but highly dangerous acid that binds calcium in the body and etches glass.
Hydrofluoroether
A hydrofluoroether (HFE) is a fluorinated ether developed by 3M in the 1990s as a replacement for ozone-depleting CFCs, used in precision cleaning, aerosols, and heat-transfer fluids.
Hydrofoil
A hydrofoil is a boat with underwater wing-like foils that lift its hull clear of the water at speed, cutting drag and enabling higher speeds.
Hydroforming
Hydroforming is a metal-forming process that uses pressurized fluid to expand tubes or sheets against a die, making parts like engine cradles and exhaust components.
Hydroformylation
Hydroformylation, also called the oxo process or oxo synthesis, is the catalytic addition of carbon monoxide and hydrogen to an alkene to form aldehydes, used industrially since 1938.
Hydrofunctionalization
Hydrofunctionalization is the addition of a hydrogen atom and a functional group across an unsaturated carbon–carbon bond, most often of an alkene or alkyne, an atom- and step-efficient strategy in organic synthesis.
Hydrogel
A hydrogel is a three-dimensional network of hydrophilic polymer chains that absorbs and retains water without dissolving, used in contact lenses, drug delivery, and wound care.
Hydrogel actuator
A hydrogel actuator is a soft actuator built from a water-swollen polymer network that converts stimuli like heat, light, or electricity into motion, used in soft robotics and grippers.
Hydrogel bioelectronics
Hydrogel bioelectronics is a branch of bioelectronics in which water-rich hydrogels form the interface between soft biological tissue and rigid electronics, enabling neural recording, stimulation, and wearables.
Hydrogel ionotronics
Hydrogel ionotronics is a branch of soft electronics in which stretchable, transparent hydrogels serve as ionic conductors, coupling mobile ions with electrons in devices like electronic skin and soft actuators.
Hydrogel microparticles
Hydrogel microparticles, also called microgels or hydrogel microspheres, are water-swollen, crosslinked polymer networks that can absorb several times their weight in water, used in drug delivery, tissue engineering, biosensing, and 3D bioprinting.
Hydrogel optical fibers
Hydrogel optical fibers are light-guiding filaments of water-swollen, cross-linked hydrophilic polymers with tissue-like softness, developed for biosensing, optogenetic stimulation, and photothermal therapy where rigid silica fibers damage tissue.
Hydrogel synthesis
Hydrogel synthesis is the set of chemical routes that form crosslinked hydrophilic polymer networks holding at least 10% water, used in contact lenses, drug delivery, and tissue engineering.
Hydrogen
Hydrogen, the lightest and simplest chemical element with atomic number 1, is the most abundant element in the universe and the fuel burned by stars like the Sun.
Hydrogen atom
The hydrogen atom, or atomic hydrogen, consists of a single proton and a single electron bound by Coulomb attraction, making it the simplest atom and the reference system of atomic physics.
Hydrogen atom transfer
Hydrogen atom transfer (HAT) is a chemical reaction in which a proton and an electron move together as a hydrogen atom between substrates in a single step.
Hydrogen atom transfer catalysis with thiols
Hydrogen atom transfer catalysis with thiols is a family of radical reactions in which thiol catalysts deliver or remove hydrogen atoms to generate radical intermediates.
Hydrogen atom transfer hydrofunctionalization
Hydrogen atom transfer (HAT) hydrofunctionalization adds a hydrogen atom and a functional group across an alkene, typically via cobalt metal hydride catalysis, giving Markovnikov products.
Hydrogen atom transfer photocatalysis
Hydrogen atom transfer (HAT) photocatalysis is a strategy in organic synthesis that uses light-absorbing catalysts to abstract hydrogen atoms, converting C–H bonds into C–C and C–heteroatom bonds.
Hydrogen atom transfer/nickel catalysis
Hydrogen atom transfer/nickel (HAT/nickel) catalysis is a cross-coupling method in which a HAT catalyst generates carbon radicals from C–H bonds and nickel couples them with aryl or alkyl halides, introduced in 2016 by David MacMillan.
Hydrogen attack
Hydrogen attack is the irreversible deterioration of steel caused by hydrogen at high temperature, where hydrogen reacts with carbon to form methane inside the metal.