All articles starting with H
20,046 articles
Hydrogen sulfide scavenging
Hydrogen sulfide scavenging is the removal of hydrogen sulfide from oil and gas streams by an irreversible chemical reaction, most often using aqueous triazine solutions such as MEA-triazine.
Hydrogen sulfide splitting
Hydrogen sulfide splitting is the decomposition of hydrogen sulfide (H₂S) into hydrogen and sulfur, pursued as a refinery waste treatment and a low-energy route to clean hydrogen.
Hydrogen Systems (company)
Hydrogen Systems is the name of several unrelated companies, including a Belgian electrolyser patent assignee, a Russian Norilsk Nickel fuel-cell venture, and a Saudi distributor.
Hydrogen therapy
Hydrogen therapy is a medical treatment administering molecular hydrogen by inhalation, hydrogen-rich water, or saline, aiming to reduce oxidative stress and inflammation in a range of diseases.
Hydrogen train
A hydrogen train is a rail vehicle using a fuel cell to turn onboard hydrogen into electricity, emitting only water; the first entered service in Germany in 2018.
Hydrogen trapping
Hydrogen trapping is the binding of dissolved hydrogen atoms to defects and interfaces in a metal lattice, such as dislocations and grain boundaries, slowing hydrogen diffusion and altering embrittlement risk.
Hydrogen valley
A hydrogen valley is a geographically defined region where hydrogen production, storage, distribution, and local end use grow together as one integrated regional value chain.
Hydrogen vehicle
A hydrogen vehicle is a motor vehicle that uses hydrogen as its energy source, most commonly a fuel cell electric vehicle whose exhaust is only water vapor.
Hydrogen water
Hydrogen water (hydrogen-rich water) is water with dissolved molecular hydrogen gas, made by pressurized infusion, electrolysis, or magnesium tablets; FDA GRN 520 covers beverage use, and clinical evidence remains small-scale and mixed.
Hydrogen water chemistry
Hydrogen water chemistry (HWC) is a boiling water reactor practice, developed in the United States in the late 1970s, that injects hydrogen into feedwater to stop stress corrosion cracking.
Hydrogen-bonded organic framework
A hydrogen-bonded organic framework (HOF) is a crystalline porous material whose organic building units are linked by hydrogen bonds, studied since the first microporous example in 2011.
Hydrogen-filled capillary discharge waveguide
A hydrogen-filled capillary discharge waveguide is a plasma waveguide for high-intensity laser pulses, formed by firing an electrical discharge through hydrogen gas confined in a narrow dielectric capillary.
Hydrogen-powered aircraft
A hydrogen-powered aircraft, also known as a hydrogen plane, is an aircraft that burns hydrogen in gas turbines or converts it to electricity in fuel cells, emitting no carbon dioxide.
Hydrogen–deuterium exchange mass spectrometry
Hydrogen–deuterium exchange mass spectrometry (HDX-MS) measures the exchange of protein backbone amide hydrogens with deuterium from solvent, using the resulting mass shifts to map protein structure, dynamics, and interactions.
Hydrogen–deuterium exchange measurement
Hydrogen–deuterium exchange measurement (HDX) is a biophysical technique that monitors exchange of protein backbone amide hydrogens with solvent deuterium, most often by mass spectrometry, to characterize protein structure and dynamics.
Hydrogenase
Hydrogenase, also called H2ase, is a metalloenzyme catalyzing H2 ⇌ 2H+ + 2e−. Three classes exist, [NiFe], [FeFe], and [Fe], distinguished by active-site metals, catalytic bias, and oxygen tolerance.
Hydrogenase mimic
A hydrogenase mimic is a synthetic molecule, material, or biohybrid construct that reproduces the structure or catalytic behavior of hydrogenase, the natural enzyme interconverting protons, electrons, and hydrogen.
Hydrogenase-mimetic nickel electrocatalysts for H2 oxidation
Hydrogenase-mimetic nickel electrocatalysts for H2 oxidation are molecular nickel bis(diphosphine) complexes with pendant amine proton relays, developed at PNNL as inexpensive, CO-tolerant alternatives to platinum in fuel cells.
Hydrogenated soy lecithin
Hydrogenated soy lecithin, or hydrogenated soy phosphatidylcholine (HSPC), is soybean lecithin with unsaturated fatty acids saturated by catalytic hydrogenation, giving higher oxidative stability; used in cosmetics, foods (GRN 534), and liposome drug carriers.
Hydrogenation
Hydrogenation, also called catalytic hydrogenation, is a chemical reaction that adds molecular hydrogen across unsaturated bonds, typically requiring a metal catalyst such as palladium, platinum, or nickel.
Hydrogenolysis
Hydrogenolysis is a catalytic reaction in which hydrogen cleaves C–C and C–O bonds in organic molecules, underpinning petroleum hydrotreating, biomass upgrading, benzyl deprotection, and plastic upcycling.
Hydrogenotrophic methanogenesis
Hydrogenotrophic methanogenesis is the methanogenic pathway in which archaea reduce carbon dioxide to methane using hydrogen or formate, the route most methanogens use in anoxic habitats.
Hydrogeology and water management of the Yucatán aquifer
The hydrogeology and water management of the Yucatán aquifer, also called the Maya aquifer, cover the karst groundwater system supplying over 5 million people in Mexico's Yucatán Peninsula.
Hydrogeomorphic approach to wetland classification and assessment
The hydrogeomorphic (HGM) approach is a US method for classifying wetlands and scoring their ecological functions, developed by the Army Corps of Engineers in the early 1990s.
Hydrograph separation
Hydrograph separation is a hydrology method that splits a streamflow hydrograph into baseflow and quickflow, using graphical, digital-filter, or tracer mass-balance techniques to quantify how catchments generate runoff.
Hydrographer of the Navy
The Hydrographer of the Navy is the senior Royal Navy officer heading Britain's naval hydrographic effort, overseeing Admiralty charts since the office was created in 1795.
Hydrographers Range
Hydrographers Range: forested andesitic volcanic massif in Oro Province, Papua New Guinea, extending from Mount Lamington's eastern margin to the coast; 1,915 m, Pleistocene stratovolcano, no confirmed Holocene eruptions.
Hydrographic network
Hydrographic network: geospatial datasets of surface water features (rivers, lakes, dams) and their connections, also called hydrospatial networks; examples include the US NHD/NHDPlus, Canada's CHN and NHN, and global HydroSHEDS.
Hydrographic office
A hydrographic office is a national agency responsible for surveying a country's waters and producing the nautical charts, tide tables, and Notices to Mariners that ships need to navigate safely.
Hydrographic survey
Hydrographic survey is the measurement of water depth and seafloor features to produce bathymetric models and nautical charts, using single-beam and multibeam echo sounders, airborne LiDAR, and satellite-derived bathymetry.