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Hybris (band) Hybris is a gothic rock band formed during a cold winter in the city of Kiel, in Northern Germany in 1998. The local musician scene was mostly represented by heavy- and trash-metal bands, but gothic and other dark music styles are quite popular at several clubs and local events.
Hybrot A hybrot (short for "hybrid robot") is a cybernetic organism in the form of a robot controlled by a computer consisting of both electronic and biological elements. The biological elements are rat neurons connected to a computer chip.
Hydantoin Hydantoin, which is also known as glycolylurea, is a heterocyclic organic compound which can be thought of as a cyclic "double-condensation reaction" product of glycolic acid and urea. Its chemical structure, shown in the Table of Properties at right, is similar to imidazolidine except that the molecule has carbonyl groups in the number 2 and 4 positions in the ring.
Hydathode A hydathode is a type of tissue in leaves, usually more advanced plant species, that permits the release of water through pores in the epidermis or margin of leaves. They probably evolved from modified stomata.
Hyde (UK Parliament constituency) Hyde was a parliamentary constituency represented in the House of Commons of the Parliament of the United Kingdom from 1885 until 1918. It was based around the town of Hyde, formerly in Cheshire but now part of Greater Manchester.
Hyde End Hyde End is a small hamlet in Buckinghamshire. Not really qualifying for the accolade "village", it is a row of thirties cottages and one or two large houses along the main road between Chesham and Great Missenden.
Hyde Memorial Observatory Hyde Memorial Observatory is a community astronomical observatory located in Lincoln, Nebraska (USA) surrounded Holmes lake. It is run totally by volunteers, furnished through public donations, and devoted purely to public viewing.
Hyde Park Corner (shopping centre) Hyde Park Corner is a shopping centre in Johannesburg, South Africa. It is located in Hyde Park and was completed in November 1969 as one of the first fully-enclosed decentralised shopping centres in South Africa.
Hyde Park Gate Hyde Park Gate is an address in London, England, which applies to two parallel roads in Kensington on the southern boundary of Kensington Gardens. It is probably most famous for being the death place of Sir Winston Churchill.
Hyde Park Herald The Hyde Park Herald is a weekly newspaper that serves the Hyde Park neighborhood of Chicago, Illinois. The newspaper was founded in 1882, and claims on its masthead to be "Chicago's Oldest Community Newspaper.
Hyde Park House The Hyde Park House was an upscale hotel built and run by Paul Cornell, that served as the centerpiece for Hyde Park social life from 1857 until 1879. It was located on 53rd Street adjacent to Lake Michigan on land currently occupied by the Hampton House.
Hyde Park Picture House Hyde Park Picture House in the Hyde Park area of Leeds, England, was originally built as a hotel in 1908 and converted to a cinema in 1914. It is a beautiful example of an Edwardian venue and one of the only surviving picture palaces in the United Kingdom.
Hyde Park Theatre Founded in 1992, Hyde Park Theatre (formerly Frontera@Hyde Park Theatre) is an arts centers in Austin, Texas, that has produced over 50 world and regional premieres. In addition to a mainstage season, HPT curates the largest performance festival in the Southwest, FronteraFest.
Hyde Park, Austin, Texas Hyde Park, served by the Hyde Park Neighborhood Association, is a historic neighborhood in Central Austin, located just north of The University of Texas. The neighborhood was originally developed by Monroe Martin Shipe in 1891 as a streetcar suburb with a large artificial lake, but it has since become one of the most densely populated areas in the city's urban core.
Hyde Park, Boise, Idaho A part of a Boise, ID, neighborhood known as the "North End" consisting of a number of popular eateries and shops, located on North 13th Street. Each month, the local merchants host a block party called "13th on 13th", coinciding with the 13th of the month.
Hyde Park, Guyana Hyde Park is a community in the Demerara-Mahaica Region of Guyana. It stands on the right bank of the Demerara River, at two metres above sea level, about 40 km upstream from the river's mouth, and Georgetown.
Hyde Park, Chicago Hyde Park is a neighborhood on the south side of Chicago, located seven miles south of the Chicago Loop. It is home to The DuSable Museum of African American History, the Hyde Park Art Center, the Museum of Science and Industry, The Renaissance Society, and the University of Chicago.
Hyde Park, Western Australia Hyde Park (formerly Third Swamp Reserve) is an inner-city park in Perth, Western Australia. Located within the Town of Vincent, the park is 2 km north of the CBD, surrounded by Vincent, William, Glendower and Throssell Streets.
Hyde Park/53rd St. (Metra) The Hyde Park--53rd St. Station commuter rail station within the city of Chicago serves the Metra Electric Line north to the Randolph Street Terminal and south to University Park, Blue Island, and South Chicago.
Hyder Consulting Hyder Consulting is a planning, engineering, environmental and management consultancy that works in the public and private sectors to develop complex buildings and infrastructure. The firm employs over 2,500 people and was listed on the London Stock Exchange in October 2002.
Hyderabad House Hyderabad House is a former Princely Residence of the Nizam of Hyderabad that now is used by the Government of India for banquets and meetings with visiting foreign dignitaries. It has also been a venue for joint press conferences and other media events, located in New Delhi, Delhi.
Hyderabad Public School The Hyderabad Public School, Begumpet (HPS, Begumpet), Begumpet, is one of the oldest and most prestigious public schools in Hyderabad and Andhra Pradesh. It was established in 1923 as a school for the members of the then Indian aristocracy.
Hyderabad Rationalist Forum Hyderabad Rationalist Forum (HRF) is an Indian rationalist group based in the twin cities of Hyderabad and Secundarabad in Andhra Pradesh, India. It aims to spread rationalist, humanist and atheist ideas and to encourage intercultural marriages and to curb superstitious practices.
Hyderabad State HyderÄbÄd and Berar (Telugu: ŕ°ąŕ±ŕ°¦ŕ°°ŕ°ľŕ°¬ŕ°ľŕ°¦ŕ± Urdu: Řیدر آباد) under the Nizams, was the largest princely state in India. The area of the state was bigger than Great Britain including Scotland.
Hyderabad-Karnataka Liberation Day The Hyderabad-Karnataka liberation day is celebrated by the Government of Karnataka to comemmorate the liberation and subsequent integration of the districts of Bidar, Gulbarga and Raichur with Karnataka state. It is observed on the 17th of September every year.
Hydestyle Hydestyle is a hamlet between the villages of Busbridge and Hambledon, a few miles south of Godalming in south west Surrey. Hydestyle is a very densely wooded area and is notable for Hydon's Ball (a steep, wooded hill), a Cheshire Home, and its wildlife hospital.
Hydnocarpus Hydnocarpus is genus of medium to large trees (family Flacourtiaceae) of Indonesia, Malaysia and the Philippines, having alternate leaves, small dioecious racemose flowers, and capsular fruits of which several are sources of chaulmoogra oil and hydnocarpus oil.
Hydra (Dungeons & Dragons) In the Dungeons & Dragons fantasy role-playing game, the hydra is a reptilian magical beast that has anywhere from five to twelve heads. A hydra is an especially deadly monster, since every time a head is severed, two new ones grow in its place.
Hydra (software) Hydra is a software project developed by "The Hacker's Choice" (THC) that uses a dictionary attack to test for weak or simple passwords on one or many remote hosts running a variety of different services. It was designed as a proof-of-concept utility to demonstrate the ease of cracking poorly chosen passwords.
Hydra the Revenge Hydra the Revenge is a steel floorless roller coaster at Dorney Park & Wildwater Kingdom in South Whitehall Township, Pennsylvania (USA). It was built where the Wooden roller coaster Hercules stood, which was closed for demolition at the end of the park's 2003 season.
Hydra-Cannon The Hydra-Cannon is a powerful weapon in the Transformers: Armada cartoon series. Created by the Decepticon Thrust, it is powered by the three legendary Mini-Con weapons: the Star Saber, the Skyboom Shield, and the Requiem Blaster.
Hydra-Centaurus Supercluster The Hydra-Centaurus Supercluster, or the Hydra and Centaurus superclusters, is a supercluster in two parts and the closest neighbour of Milky Way's Local Supercluster. The cluster includes four large galaxy clusters in the Centaurus part (A3526 (Centaurus cluster),A3565, A3574, A3581) and the proximity Hydra Cluster (A1060) and Norma cluster (A3627).
Hydra, Saronic Islands Hydra (Greek: ΥδĎα, IPA pronunciation: ) is one of the Saronic Islands of Greece, located in the Aegean Sea between the Saronic Gulf and the Argolic Gulf. It is separated from the Peloponnese by the narrow Hydra Gulf.
Hydralazine Hydralazine hydrochloride (1-hydrazinophthalazine monohydrochloride; Apresoline®) is a medication used to treat high blood pressure. A vasodilator, hydralazine works by relaxing blood vessels (arterioles more than venules) and increasing the supply of blood and oxygen to the heart while reducing its workload.
Hydramatic Hydramatic (also known as Hydra-Matic) was an automatic transmission developed by General Motors's Oldsmobile division. Introduced for the 1940 model year, the Hydramatic was the first fully automatic mass-produced transmission developed for passenger automobile use.
Hydran Kingdom In the fictional Star Fleet Universe the Hydrans are an original race developed specifically for the game universe. They are enemies of the Lyran Star Empire and the Klingon Empire, both of whom have occupied Hydran territory before.
Hydrangea Hydrangea (common names also Hydrangea, pronounced haidréindʒiə, and Hortensia) is a genus of about 70-75 species of flowering plants native to southern and eastern Asia (from Japan to China, the Himalaya and Indonesia) and North and South America. By far the greatest species diversity is in eastern Asia, notably China and Japan.
Hydrargyrum medium-arc iodide Hydrargyrum medium-arc iodide, or HMI, is a mercury-halide gas discharge medium arc-length lamp with a multi-line spectra emission. The name implies that hydrargyrum, an archaic term for Mercury (Hg), is held as a vapour mixed with other rare halides in a quartz-glass envelope with two tungsten-coated electrodes of medium arc separation.
Hydrargyrum quartz iodide Hydrargyrum quartz iodide (HQI) is a special type of high-intensity discharge (or HID) lighting, where the light is produced using a very high voltage electrical arc through a gas. The "H" in "HQI" comes from hydrargyrum, the Latin name for the element mercury.
Hydrated ionic compound Hydrated ionic compounds are those ionic compounds which contain water molecules inside their crystal lattice. The water is not chemically bonded to the crystal in any way, and may be driven off by heating the hydrated compound.
Hydration pack A hydration pack is a backpack or waistpack containing a [or "bladder" commonly made of rubber] or flexible [[plastic. The reservoir contains a capped mouth for filling with liquid and a hose that allows the wearer to drink hands-free.
Hydration reaction In organic chemistry, a hydration reaction is a chemical reaction in which a hydroxyl group (OH-) and a hydrogen cation (an acidic proton) are added to the two carbon atoms bonded together in the carbon-carbon double bond which makes up an alkene functional group. The reaction usually runs in a strong acidic, aqueous solution.
Hydration system In recreation and other sustained outdoor activities, a hydration system is an apparatus intended to promote its user's drinking enough liquid to support the physical effort involved in the activity. Such systems for consumers were first sold to cyclists, but by the 1990s also had found a substantial market among hikers.
Hydraulic analogy The electronic Hydraulic analogy (derisively referred to as the Drain-pipe theory by Oliver Heaviside) is the most widely used analogy for "electron fluid" in a metal conductor. Since electric current is invisible and the processes at play in electronics are often difficult to understand in an intuitive way, it is common to teach electronics using analogies to everyday objects and processes.
Hydraulic brake The hydraulic brake is an arrangement of braking mechanism which uses hydraulic fluid, typically some type of light-viscosity silicone oil, to transfer pressure from the controlling unit, which is usually near the operator of the vehicle, to the actual brake mechanism, which is usually at or near the wheel of the vehicle.
Hydraulic conductivity Hydraulic conductivity, symbolically represented as K, is a property of soil or rock, that describes the ease with which water can move through pore spaces or fractures. It depends on the intrinsic permeability of the material and on the degree of saturation.
Hydraulic empire A hydraulic empire, also known as a hydraulic despotism or water monopoly empire, is a social or government structure which maintains power and control through exclusive control over access to water. It arises through the need for flood control and irrigation, which requires central coordination and a specialized bureaucracy.
Hydraulic engineering Hydraulic engineering is a sub-discipline of civil engineering concerned with the flow and conveyance of fluids, principally water. This area of engineering is intimately related to the design of bridges, dams, channels, canals, levees, elevators, and to both sanitary and environmental engineering.
Hydraulic fill A hydraulic fill is an embankment or other fill in which the materials are deposited in place by a flowing stream of water, with the deposition being selective. Gravity, coupled with velocity control, is used to effect the selected deposition of the material.
Hydraulic fluid Hydraulic fluids are a large group of liquids made of many kinds of chemicals. They are used in automobile automatic transmissions, brakes, and power steering; forklift trucks; tractors; bulldozers; industrial machinery; and aircraft.
Hydraulic head Hydraulic head is a specific measurement of water pressure or total energy per unit weight above a datum. It is usually measured as a water surface elevation, expressed in units of length, but represents the energy at the entrance (or bottom) of a piezometer.
Hydraulic lifters A hydraulic lifter, also known as a hydraulic tappet or a hydraulic lash adjuster, is a device for maintaining zero valve clearance in an internal combustion engine. Conventional means of adjusting valve actuation always require a small clearance to be left between the valve and its rocker or cam follower to allow for thermal expansion and wear, as it is vital that a valve must never be prevented from closing completely; this rapidly burns it away, especially in the case of the exhaust valve.
Hydraulic manifold A hydraulic manifold is a component which regulates fluid flow between pumps and actuators and other components in a hydraulic system. It is like a switchboard in an electrical circuit because it lets the operator control how much fluid flows between which components of a hydraulic machinery.
Hydraulic mining Hydraulic mining, or hydraulicking, is a form of mining that employs water under pressure to dislodge rock material or move sediment. This form of mining was used in the region around Nevada City, California, c.
Hydraulic network A hydraulic network is a system of interconnected pipes carrying pressurized liquid used to transmit mechanical power from a power source, like a pump, to hydraulic equipment like lifts or motors. The system is analogous to an electrical grid transmitting power from a generating station to end-users.
Hydraulic press A hydraulic press is a hydraulic mechanism for applying a large lifting or compressive force. It is the hydraulic equivalent of a mechanical lever, and is also known as a Bramah press after the inventor, Joseph Bramah.
Hydraulic seal A hydraulic seal is a relatively soft, non-metallic ring captured in a groove or fixed in a combination of rings, forming a seal assembly, to block or separate fluid in reciprocating motion applications. Hydraulic seals are vital in machinery.
Hydrauliska Industri AB Hydrauliska Industri AB (Hiab) is a Finnish manufacturer of loader cranes, demountable containers, forestry cranes, truck-mounted forklifts and tail lifts. In some countries, 'HIAB' (pronounced high'-ab) is used as a synonym for a loader crane of any make.
Hydrazide Hydrazides in organic chemistry are a class of organic compounds sharing a common functional group characterized by a nitrogen to nitrogen covalent bond with 4 substituents with at least one of them this acyl group. The general structure for an hydrazide is R1R2-N-N-R3R4.
Hydreuma In Hellenistic and Roman Arabia and Egypt, a hydreuma (plural hydreumata) was an enclosed (and often fortified) "watering station" (Greek hydros, "water") at wadis in dry regions. A hydreuma was a manned and fortified watering hole or way station along a caravan route, providing a man-made oasis.
Hydric soil A hydric soil is a soil that formed under conditions of saturation, flooding, or ponding long enough during the growing season to develop anaerobic conditions in the upper part.This definition (Federal Register, July 13, 1994) replaced the older 1991 version and accomplished two things.
Hydride Hydride is the name given to the negative ion of hydrogen, Hâ’. It is also used as a more general term to describe compounds of hydrogen with other elements, particularly those of groups 1–16, whether or not they actually contain hydride ions.
Hydride vapour phase epitaxy Hydride Vapour Phase Epitaxy or HVPE, is an epitaxial growth technique often employed to produce semiconductors such as GaN, GaAs, InP and their related compounds. Carrier gasses commonly used include Ammonia, Hydrogen and various Chlorides.
Hydrino Hydrino is a name for a hydrogen atom in a hypothetical state which is supposed to be of lower energy than the ground state of hydrogen. Related to it are hypothetical ions and compounds of hydrogen that are supposed to have exceptionally high bond energies, and so present potentially a source of power much higher than that available from conventional chemical reactions.
Hydrino theory Hydrino theory is a colloquial term for one aspect of a controversial Grand Unified Theory developed by Randell Mills, termed "Classical Quantum Mechanics", which is claimed to be entirely based on classical physics, rejecting well-established quantum theory. The main feature of Mills's hypothesis is its "orbitsphere" model of the electron, where atomic electrons are spherical shells of charge surrounding the nucleus.
Hydrion paper Hydrion is a trademarked name for a popular line of compound pH indicators, marketed by Micro Essentials Laboratory, exhibiting a series of color changes (typically producing a recognizably different color for each pH unit) over a range of pH values. Although solutions are available, the most common forms of Hydrion are a series of papers impregnated with various mixtures of indicator dyes.
Hydriotaphia, Urn Burial Hydriotaphia, Urn Burial, or a Discourse of the Sepulchral Urns lately found in Norfolk, is a work published in 1658 by Sir Thomas Browne. It was published as the first part of a two-part work that concludes with The Garden of Cyrus.
Hydro massage Hydro massage is a type of massage based on the therapeutic use of warm water. The essence of hydro massage is applying massage techniques to the human body (thermally, mechanically, or chemically) through the water (which can be mineral, acerous or any other).
Hydro pump Hydro Pump is the name of a powerful high-tier water-type attack in the Pokemon series of videogames,anime,trading cards,and apparel created by Satoshi Tajiri. It is the most powerful water-based attack in the Pokemon series,and can only be learned by water-type Pokemon through either battle experience or by using a TM.
Hydro-Electric Power Commission of Ontario The Hydro-Electric Power Commission of Ontario was established in 1906 by the provincial Power Commission Act to build transmission lines to supply municipal utilities with electricity generated by private companies already operating at Niagara Falls. The first chairman was Adam Beck, minister without portfolio in the provincial government of Sir James P.
Hydroacoustics Hydroacoustics is a general term for the study and application of sound in water. Hydroacoustics, utilizing SONAR technology, is most commonly used for detection, assessment, and monitoring of underwater physical and biological characteristics.
Hydroamination The hydroamination reaction is the addition an N-H bond across the C=C or C=C of an alkene or alkyne. This is a highly atom economical method of preparing substituted amines that are attractive targets for organic synthesis and the pharmaceutical industry.
Hydrobiology Hydrobiology is the science of life and life processes in water. Much of modern hydrobiology can be viewed as a sub-discipline of ecology but the sphere of hydrobilogy includes taxonomy, economic biology, industrial biology, morphology, physiology etc.
Hydroblading Hydroblading is a moves in the field element of figure skating in which a skater glides on a deep edge with the body stretched in a very low position, almost horizontal to the ice. Several variations in position are possible, but one commonly performed by singles skaters is on a back inside edge with the knee of the skating leg deeply bent, the free leg crossed behind and extended outside the circle, and the upper body leaning into the circle with one hand skimming the ice.
Hydroboration-oxidation reaction In organic chemistry, the hydroboration-oxidation reaction is a two-step organic chemical reaction that converts an alkene into a neutral alcohol by the net addition of water across the double bond Organic Chemistry Help. Hydroboration of alkenes.
Hydrocarbon A hydrocarbon is a chemical compound that consists only of the elements carbon (C) and hydrogen (H). Hydrocarbons contain a backbone consisting of carbon atoms, called a carbon skeleton with hydrogen atoms attached to that backbone.
Hydrocarbon dew point The hydrocarbon dew point is the temperature (at a given pressure) at which the hydrocarbon components of any hydrocarbon-rich gas mixture, such as natural gas, will start to condense out of the gaseous phase. It is often also referred to as the HDP or the HCDP.
Hydrocarbons on other planets Basic hydrocarbons are ubiquitous in the atmospheres of Jupiter and Saturn. The parent molcule, methane (CH4), undergoes photochemical reactions which convert it to chain molecules such as acetylene (C2H2), ethylene (C2H4), and ethane (C2H6).
Hydrocephalus Hydrocephalus, sometimes known as Water on the Brain, is a condition in which abnormal accumulation of cerebrospinal fluid (CSF) in the brain causes increased intracranial pressure inside the skull. This is usually due to blockage of CSF outflow in the brain ventricles or in the subarachnoid space at the base of the brain.
Hydrocodone Hydrocodone or dihydrocodeinone (marketed as Vicodin, Anexsia, Dicodid, Hycodan, Hycomine, Lorcet, Lortab, Norco, Novahistex, Hydroco, Tussionex, Vicoprofen) is a semi-synthetic opioid derived from two of the naturally occurring opiates, codeine and thebaine. Hydrocodone is an orally active narcotic analgesic and antitussive.
Hydrocolloids Hydrocolloids describe certain chemicals (mostly polysaccharides and proteins) that are colloidally dispersible in water. Thus becoming effectively "soluble" they change the rheology of water by raising the viscosity and/or inducing gelation.
Hydrocotyle Hydrocotyle is a genus of aquatic or semi-aquatic plants formerly classified in the family Apiaceae, now in the family Araliaceae. At least two species are now classed as invasive aliens following introductions outside of their normal range.
Hydrocotyle ranunculoides Hydrocotyle ranunculoides , known as water pennywort or floating pennywort is an aquatic member of the Ranunculaceae. In the UK it is an invasive alien species which is currently spreading in waterways in England and Wales.
Hydrocotyle umbellata Hydrocotyle umbellata, is an aquatic, or water-loving, perennial that thrives in warm, temperate regions. Its is known as dollarweed, marsh or water pennywort or navelwort although the latter names are also used for unrelated plants such as Umbilicus rupestris.
Hydrodaktulopsychicharmonica The hydrodaktulopsychicharmonica is a type of musical instrument consisting of a series of crystal glasses made up of varying amount of water. It, or instruments like it, helped inspire Benjamin Franklin's glass harmonica.
Hydrodealkylation Hydrodealkylation is a chemical reaction that often involves reacting an aromatic hydrocarbon such as toluene in the presence of hydrogen gas to form a simpler aromatic hydrocarbon devoid of functional groups, for example, converting 1,2,4-trimethylbenzene to xylene.Free Patents Online
Hydrodesulfurization Hydrodesulfurization (HDS) is a catalytic chemical process widely used to remove sulfur (S) from natural gas and from refined petroleum products such as gasoline or petrol, jet fuel, kerosene, diesel fuel, and fuel oils.Hydrodesulfurization Technologies and Costs Nancy Yamaguchi, Trans Energy Associates, William and Flora Hewlett Foundation Sulfur Workshop, Mexico City, May 29-30, 2003 The purpose of removing the sulfur is to reduce the sulfur dioxide (SO2) emissions that result from using those fuels in automotive vehicles, aircraft, railroad locomotives, ships, gas or oil burning power plants, residential and industrial furnaces, and other forms of fuel combustion.
Hydroelectricity [upper reservoir and dam of the Ffestiniog Pumped-Storage Scheme in north Wales].The power station at the lower reservoir has four water turbines which can generate 360 megawatts of electricity within 60 seconds of the need arising.
Hydrofoil board The Foilboard is a type of surfboard equipped with a hydrofoil that extends below the board, causing the board to completely lift out of the water at high speeds. A jetski is used to pull the surfer into a wave.
Hydroformylation Hydroformylation, also known as oxo synthesis, is an important industrial process for the production of aldehydes from alkenes. This chemical reaction entails the addition of a formyl group (CHO) group and a hydrogen atom to a carbon-carbon double bond.
Hydrogel Hydrogel is a network of polymer chains that are water-soluble, sometimes found as a colloidal gel in which water is the dispersion medium. Hydrogels are superabsorbent (they can contain over 99% water) natural or synthetic polymers.
Hydrogen bond A hydrogen bond is a special type of attractive interaction that exists between an electronegative atom and a hydrogen atom bonded to another electronegative atom. This type of bond always involves a hydrogen atom, thus the name.
Hydrogen Breath Test A Hydrogen Breath Test (or HBT) is used as a clinical medical diagnosis for people with irritable bowel syndrome, and common food intolerances. The test is simple, non-invasive, and is performed after a short period of fasting (typically 8 hours).
Hydrogen carrier A hydrogen carrier is an organic macromolecule that transports atoms of hydrogen from one place to another inside a cell or from cell to cell for use in various metabolical processes. An example is NADPH in photosynthesis.
Hydrogen embrittlement Hydrogen embrittlement (or hydrogen grooving) is the process by which various metals, most importantly high-strength steel, become brittle and crack following exposure to hydrogen. Hydrogen cracking can pose an engineering problem especially in the context of a hydrogen economy.
Hydrogen fuel injection Hydrogen Fuel Injection, or HFI, is a system to reduce exhaust emissions of internal combustion engines and improve fuel economy. HFI systems work by injecting hydrogen as a combustion enhancement into the intake manifold of an internal combustion engine to achieve these benefits.
Hydrogen halide Hydrogen halides (or hydrohalic acids) are acids resulting from the chemical reaction of hydrogen with one of the halogen elements (fluorine, chlorine, bromine, iodine), which are found in group VII of the periodic table. Astatine is not included in the list because it is very rare, unstable and not found as the acid in substantial quantities.
Hydrogen highway A hydrogen highway is a chain of hydrogen-equipped filling stations and other infrastructure along a road or highway which allow hydrogen powered cars to travel. A hydrogen filling infrastructure is generally assumed to be a pre-requisite for mass utilization of hydrogen cars.
Hydrogen hypothesis The hydrogen hypothesis is a model proposed by William Martin and Miklos Muller in 1998 that describes a possible way in which the mitochondrion developed in the first eukaryotic cell within the endosymbiotic theory framework.
Hydrogen storage Hydrogen storage is the main technological problem of a viable hydrogen economy. Some attention has been given to the role of hydrogen to provide grid energy storage for unpredictable energy sources, like wind power, but most research into hydrogen storage is focussed on storing hydrogen in a lightweight, compact manner for mobile applications.
Hybrot A hybrot (short for "hybrid robot") is a cybernetic organism in the form of a robot controlled by a computer consisting of both electronic and biological elements. The biological elements are rat neurons connected to a computer chip.
Hydantoin Hydantoin, which is also known as glycolylurea, is a heterocyclic organic compound which can be thought of as a cyclic "double-condensation reaction" product of glycolic acid and urea. Its chemical structure, shown in the Table of Properties at right, is similar to imidazolidine except that the molecule has carbonyl groups in the number 2 and 4 positions in the ring.
Hydathode A hydathode is a type of tissue in leaves, usually more advanced plant species, that permits the release of water through pores in the epidermis or margin of leaves. They probably evolved from modified stomata.
Hyde (UK Parliament constituency) Hyde was a parliamentary constituency represented in the House of Commons of the Parliament of the United Kingdom from 1885 until 1918. It was based around the town of Hyde, formerly in Cheshire but now part of Greater Manchester.
Hyde End Hyde End is a small hamlet in Buckinghamshire. Not really qualifying for the accolade "village", it is a row of thirties cottages and one or two large houses along the main road between Chesham and Great Missenden.
Hyde Memorial Observatory Hyde Memorial Observatory is a community astronomical observatory located in Lincoln, Nebraska (USA) surrounded Holmes lake. It is run totally by volunteers, furnished through public donations, and devoted purely to public viewing.
Hyde Park Corner (shopping centre) Hyde Park Corner is a shopping centre in Johannesburg, South Africa. It is located in Hyde Park and was completed in November 1969 as one of the first fully-enclosed decentralised shopping centres in South Africa.
Hyde Park Gate Hyde Park Gate is an address in London, England, which applies to two parallel roads in Kensington on the southern boundary of Kensington Gardens. It is probably most famous for being the death place of Sir Winston Churchill.
Hyde Park Herald The Hyde Park Herald is a weekly newspaper that serves the Hyde Park neighborhood of Chicago, Illinois. The newspaper was founded in 1882, and claims on its masthead to be "Chicago's Oldest Community Newspaper.
Hyde Park House The Hyde Park House was an upscale hotel built and run by Paul Cornell, that served as the centerpiece for Hyde Park social life from 1857 until 1879. It was located on 53rd Street adjacent to Lake Michigan on land currently occupied by the Hampton House.
Hyde Park Picture House Hyde Park Picture House in the Hyde Park area of Leeds, England, was originally built as a hotel in 1908 and converted to a cinema in 1914. It is a beautiful example of an Edwardian venue and one of the only surviving picture palaces in the United Kingdom.
Hyde Park Theatre Founded in 1992, Hyde Park Theatre (formerly Frontera@Hyde Park Theatre) is an arts centers in Austin, Texas, that has produced over 50 world and regional premieres. In addition to a mainstage season, HPT curates the largest performance festival in the Southwest, FronteraFest.
Hyde Park, Austin, Texas Hyde Park, served by the Hyde Park Neighborhood Association, is a historic neighborhood in Central Austin, located just north of The University of Texas. The neighborhood was originally developed by Monroe Martin Shipe in 1891 as a streetcar suburb with a large artificial lake, but it has since become one of the most densely populated areas in the city's urban core.
Hyde Park, Boise, Idaho A part of a Boise, ID, neighborhood known as the "North End" consisting of a number of popular eateries and shops, located on North 13th Street. Each month, the local merchants host a block party called "13th on 13th", coinciding with the 13th of the month.
Hyde Park, Guyana Hyde Park is a community in the Demerara-Mahaica Region of Guyana. It stands on the right bank of the Demerara River, at two metres above sea level, about 40 km upstream from the river's mouth, and Georgetown.
Hyde Park, Chicago Hyde Park is a neighborhood on the south side of Chicago, located seven miles south of the Chicago Loop. It is home to The DuSable Museum of African American History, the Hyde Park Art Center, the Museum of Science and Industry, The Renaissance Society, and the University of Chicago.
Hyde Park, Western Australia Hyde Park (formerly Third Swamp Reserve) is an inner-city park in Perth, Western Australia. Located within the Town of Vincent, the park is 2 km north of the CBD, surrounded by Vincent, William, Glendower and Throssell Streets.
Hyde Park/53rd St. (Metra) The Hyde Park--53rd St. Station commuter rail station within the city of Chicago serves the Metra Electric Line north to the Randolph Street Terminal and south to University Park, Blue Island, and South Chicago.
Hyder Consulting Hyder Consulting is a planning, engineering, environmental and management consultancy that works in the public and private sectors to develop complex buildings and infrastructure. The firm employs over 2,500 people and was listed on the London Stock Exchange in October 2002.
Hyderabad House Hyderabad House is a former Princely Residence of the Nizam of Hyderabad that now is used by the Government of India for banquets and meetings with visiting foreign dignitaries. It has also been a venue for joint press conferences and other media events, located in New Delhi, Delhi.
Hyderabad Public School The Hyderabad Public School, Begumpet (HPS, Begumpet), Begumpet, is one of the oldest and most prestigious public schools in Hyderabad and Andhra Pradesh. It was established in 1923 as a school for the members of the then Indian aristocracy.
Hyderabad Rationalist Forum Hyderabad Rationalist Forum (HRF) is an Indian rationalist group based in the twin cities of Hyderabad and Secundarabad in Andhra Pradesh, India. It aims to spread rationalist, humanist and atheist ideas and to encourage intercultural marriages and to curb superstitious practices.
Hyderabad State HyderÄbÄd and Berar (Telugu: ŕ°ąŕ±ŕ°¦ŕ°°ŕ°ľŕ°¬ŕ°ľŕ°¦ŕ± Urdu: Řیدر آباد) under the Nizams, was the largest princely state in India. The area of the state was bigger than Great Britain including Scotland.
Hyderabad-Karnataka Liberation Day The Hyderabad-Karnataka liberation day is celebrated by the Government of Karnataka to comemmorate the liberation and subsequent integration of the districts of Bidar, Gulbarga and Raichur with Karnataka state. It is observed on the 17th of September every year.
Hydestyle Hydestyle is a hamlet between the villages of Busbridge and Hambledon, a few miles south of Godalming in south west Surrey. Hydestyle is a very densely wooded area and is notable for Hydon's Ball (a steep, wooded hill), a Cheshire Home, and its wildlife hospital.
Hydnocarpus Hydnocarpus is genus of medium to large trees (family Flacourtiaceae) of Indonesia, Malaysia and the Philippines, having alternate leaves, small dioecious racemose flowers, and capsular fruits of which several are sources of chaulmoogra oil and hydnocarpus oil.
Hydra (Dungeons & Dragons) In the Dungeons & Dragons fantasy role-playing game, the hydra is a reptilian magical beast that has anywhere from five to twelve heads. A hydra is an especially deadly monster, since every time a head is severed, two new ones grow in its place.
Hydra (software) Hydra is a software project developed by "The Hacker's Choice" (THC) that uses a dictionary attack to test for weak or simple passwords on one or many remote hosts running a variety of different services. It was designed as a proof-of-concept utility to demonstrate the ease of cracking poorly chosen passwords.
Hydra the Revenge Hydra the Revenge is a steel floorless roller coaster at Dorney Park & Wildwater Kingdom in South Whitehall Township, Pennsylvania (USA). It was built where the Wooden roller coaster Hercules stood, which was closed for demolition at the end of the park's 2003 season.
Hydra-Cannon The Hydra-Cannon is a powerful weapon in the Transformers: Armada cartoon series. Created by the Decepticon Thrust, it is powered by the three legendary Mini-Con weapons: the Star Saber, the Skyboom Shield, and the Requiem Blaster.
Hydra-Centaurus Supercluster The Hydra-Centaurus Supercluster, or the Hydra and Centaurus superclusters, is a supercluster in two parts and the closest neighbour of Milky Way's Local Supercluster. The cluster includes four large galaxy clusters in the Centaurus part (A3526 (Centaurus cluster),A3565, A3574, A3581) and the proximity Hydra Cluster (A1060) and Norma cluster (A3627).
Hydra, Saronic Islands Hydra (Greek: ΥδĎα, IPA pronunciation: ) is one of the Saronic Islands of Greece, located in the Aegean Sea between the Saronic Gulf and the Argolic Gulf. It is separated from the Peloponnese by the narrow Hydra Gulf.
Hydralazine Hydralazine hydrochloride (1-hydrazinophthalazine monohydrochloride; Apresoline®) is a medication used to treat high blood pressure. A vasodilator, hydralazine works by relaxing blood vessels (arterioles more than venules) and increasing the supply of blood and oxygen to the heart while reducing its workload.
Hydramatic Hydramatic (also known as Hydra-Matic) was an automatic transmission developed by General Motors's Oldsmobile division. Introduced for the 1940 model year, the Hydramatic was the first fully automatic mass-produced transmission developed for passenger automobile use.
Hydran Kingdom In the fictional Star Fleet Universe the Hydrans are an original race developed specifically for the game universe. They are enemies of the Lyran Star Empire and the Klingon Empire, both of whom have occupied Hydran territory before.
Hydrangea Hydrangea (common names also Hydrangea, pronounced haidréindʒiə, and Hortensia) is a genus of about 70-75 species of flowering plants native to southern and eastern Asia (from Japan to China, the Himalaya and Indonesia) and North and South America. By far the greatest species diversity is in eastern Asia, notably China and Japan.
Hydrargyrum medium-arc iodide Hydrargyrum medium-arc iodide, or HMI, is a mercury-halide gas discharge medium arc-length lamp with a multi-line spectra emission. The name implies that hydrargyrum, an archaic term for Mercury (Hg), is held as a vapour mixed with other rare halides in a quartz-glass envelope with two tungsten-coated electrodes of medium arc separation.
Hydrargyrum quartz iodide Hydrargyrum quartz iodide (HQI) is a special type of high-intensity discharge (or HID) lighting, where the light is produced using a very high voltage electrical arc through a gas. The "H" in "HQI" comes from hydrargyrum, the Latin name for the element mercury.
Hydrated ionic compound Hydrated ionic compounds are those ionic compounds which contain water molecules inside their crystal lattice. The water is not chemically bonded to the crystal in any way, and may be driven off by heating the hydrated compound.
Hydration pack A hydration pack is a backpack or waistpack containing a [or "bladder" commonly made of rubber] or flexible [[plastic. The reservoir contains a capped mouth for filling with liquid and a hose that allows the wearer to drink hands-free.
Hydration reaction In organic chemistry, a hydration reaction is a chemical reaction in which a hydroxyl group (OH-) and a hydrogen cation (an acidic proton) are added to the two carbon atoms bonded together in the carbon-carbon double bond which makes up an alkene functional group. The reaction usually runs in a strong acidic, aqueous solution.
Hydration system In recreation and other sustained outdoor activities, a hydration system is an apparatus intended to promote its user's drinking enough liquid to support the physical effort involved in the activity. Such systems for consumers were first sold to cyclists, but by the 1990s also had found a substantial market among hikers.
Hydraulic analogy The electronic Hydraulic analogy (derisively referred to as the Drain-pipe theory by Oliver Heaviside) is the most widely used analogy for "electron fluid" in a metal conductor. Since electric current is invisible and the processes at play in electronics are often difficult to understand in an intuitive way, it is common to teach electronics using analogies to everyday objects and processes.
Hydraulic brake The hydraulic brake is an arrangement of braking mechanism which uses hydraulic fluid, typically some type of light-viscosity silicone oil, to transfer pressure from the controlling unit, which is usually near the operator of the vehicle, to the actual brake mechanism, which is usually at or near the wheel of the vehicle.
Hydraulic conductivity Hydraulic conductivity, symbolically represented as K, is a property of soil or rock, that describes the ease with which water can move through pore spaces or fractures. It depends on the intrinsic permeability of the material and on the degree of saturation.
Hydraulic empire A hydraulic empire, also known as a hydraulic despotism or water monopoly empire, is a social or government structure which maintains power and control through exclusive control over access to water. It arises through the need for flood control and irrigation, which requires central coordination and a specialized bureaucracy.
Hydraulic engineering Hydraulic engineering is a sub-discipline of civil engineering concerned with the flow and conveyance of fluids, principally water. This area of engineering is intimately related to the design of bridges, dams, channels, canals, levees, elevators, and to both sanitary and environmental engineering.
Hydraulic fill A hydraulic fill is an embankment or other fill in which the materials are deposited in place by a flowing stream of water, with the deposition being selective. Gravity, coupled with velocity control, is used to effect the selected deposition of the material.
Hydraulic fluid Hydraulic fluids are a large group of liquids made of many kinds of chemicals. They are used in automobile automatic transmissions, brakes, and power steering; forklift trucks; tractors; bulldozers; industrial machinery; and aircraft.
Hydraulic head Hydraulic head is a specific measurement of water pressure or total energy per unit weight above a datum. It is usually measured as a water surface elevation, expressed in units of length, but represents the energy at the entrance (or bottom) of a piezometer.
Hydraulic lifters A hydraulic lifter, also known as a hydraulic tappet or a hydraulic lash adjuster, is a device for maintaining zero valve clearance in an internal combustion engine. Conventional means of adjusting valve actuation always require a small clearance to be left between the valve and its rocker or cam follower to allow for thermal expansion and wear, as it is vital that a valve must never be prevented from closing completely; this rapidly burns it away, especially in the case of the exhaust valve.
Hydraulic manifold A hydraulic manifold is a component which regulates fluid flow between pumps and actuators and other components in a hydraulic system. It is like a switchboard in an electrical circuit because it lets the operator control how much fluid flows between which components of a hydraulic machinery.
Hydraulic mining Hydraulic mining, or hydraulicking, is a form of mining that employs water under pressure to dislodge rock material or move sediment. This form of mining was used in the region around Nevada City, California, c.
Hydraulic network A hydraulic network is a system of interconnected pipes carrying pressurized liquid used to transmit mechanical power from a power source, like a pump, to hydraulic equipment like lifts or motors. The system is analogous to an electrical grid transmitting power from a generating station to end-users.
Hydraulic press A hydraulic press is a hydraulic mechanism for applying a large lifting or compressive force. It is the hydraulic equivalent of a mechanical lever, and is also known as a Bramah press after the inventor, Joseph Bramah.
Hydraulic seal A hydraulic seal is a relatively soft, non-metallic ring captured in a groove or fixed in a combination of rings, forming a seal assembly, to block or separate fluid in reciprocating motion applications. Hydraulic seals are vital in machinery.
Hydrauliska Industri AB Hydrauliska Industri AB (Hiab) is a Finnish manufacturer of loader cranes, demountable containers, forestry cranes, truck-mounted forklifts and tail lifts. In some countries, 'HIAB' (pronounced high'-ab) is used as a synonym for a loader crane of any make.
Hydrazide Hydrazides in organic chemistry are a class of organic compounds sharing a common functional group characterized by a nitrogen to nitrogen covalent bond with 4 substituents with at least one of them this acyl group. The general structure for an hydrazide is R1R2-N-N-R3R4.
Hydreuma In Hellenistic and Roman Arabia and Egypt, a hydreuma (plural hydreumata) was an enclosed (and often fortified) "watering station" (Greek hydros, "water") at wadis in dry regions. A hydreuma was a manned and fortified watering hole or way station along a caravan route, providing a man-made oasis.
Hydric soil A hydric soil is a soil that formed under conditions of saturation, flooding, or ponding long enough during the growing season to develop anaerobic conditions in the upper part.This definition (Federal Register, July 13, 1994) replaced the older 1991 version and accomplished two things.
Hydride Hydride is the name given to the negative ion of hydrogen, Hâ’. It is also used as a more general term to describe compounds of hydrogen with other elements, particularly those of groups 1–16, whether or not they actually contain hydride ions.
Hydride vapour phase epitaxy Hydride Vapour Phase Epitaxy or HVPE, is an epitaxial growth technique often employed to produce semiconductors such as GaN, GaAs, InP and their related compounds. Carrier gasses commonly used include Ammonia, Hydrogen and various Chlorides.
Hydrino Hydrino is a name for a hydrogen atom in a hypothetical state which is supposed to be of lower energy than the ground state of hydrogen. Related to it are hypothetical ions and compounds of hydrogen that are supposed to have exceptionally high bond energies, and so present potentially a source of power much higher than that available from conventional chemical reactions.
Hydrino theory Hydrino theory is a colloquial term for one aspect of a controversial Grand Unified Theory developed by Randell Mills, termed "Classical Quantum Mechanics", which is claimed to be entirely based on classical physics, rejecting well-established quantum theory. The main feature of Mills's hypothesis is its "orbitsphere" model of the electron, where atomic electrons are spherical shells of charge surrounding the nucleus.
Hydrion paper Hydrion is a trademarked name for a popular line of compound pH indicators, marketed by Micro Essentials Laboratory, exhibiting a series of color changes (typically producing a recognizably different color for each pH unit) over a range of pH values. Although solutions are available, the most common forms of Hydrion are a series of papers impregnated with various mixtures of indicator dyes.
Hydriotaphia, Urn Burial Hydriotaphia, Urn Burial, or a Discourse of the Sepulchral Urns lately found in Norfolk, is a work published in 1658 by Sir Thomas Browne. It was published as the first part of a two-part work that concludes with The Garden of Cyrus.
Hydro massage Hydro massage is a type of massage based on the therapeutic use of warm water. The essence of hydro massage is applying massage techniques to the human body (thermally, mechanically, or chemically) through the water (which can be mineral, acerous or any other).
Hydro pump Hydro Pump is the name of a powerful high-tier water-type attack in the Pokemon series of videogames,anime,trading cards,and apparel created by Satoshi Tajiri. It is the most powerful water-based attack in the Pokemon series,and can only be learned by water-type Pokemon through either battle experience or by using a TM.
Hydro-Electric Power Commission of Ontario The Hydro-Electric Power Commission of Ontario was established in 1906 by the provincial Power Commission Act to build transmission lines to supply municipal utilities with electricity generated by private companies already operating at Niagara Falls. The first chairman was Adam Beck, minister without portfolio in the provincial government of Sir James P.
Hydroacoustics Hydroacoustics is a general term for the study and application of sound in water. Hydroacoustics, utilizing SONAR technology, is most commonly used for detection, assessment, and monitoring of underwater physical and biological characteristics.
Hydroamination The hydroamination reaction is the addition an N-H bond across the C=C or C=C of an alkene or alkyne. This is a highly atom economical method of preparing substituted amines that are attractive targets for organic synthesis and the pharmaceutical industry.
Hydrobiology Hydrobiology is the science of life and life processes in water. Much of modern hydrobiology can be viewed as a sub-discipline of ecology but the sphere of hydrobilogy includes taxonomy, economic biology, industrial biology, morphology, physiology etc.
Hydroblading Hydroblading is a moves in the field element of figure skating in which a skater glides on a deep edge with the body stretched in a very low position, almost horizontal to the ice. Several variations in position are possible, but one commonly performed by singles skaters is on a back inside edge with the knee of the skating leg deeply bent, the free leg crossed behind and extended outside the circle, and the upper body leaning into the circle with one hand skimming the ice.
Hydroboration-oxidation reaction In organic chemistry, the hydroboration-oxidation reaction is a two-step organic chemical reaction that converts an alkene into a neutral alcohol by the net addition of water across the double bond Organic Chemistry Help. Hydroboration of alkenes.
Hydrocarbon A hydrocarbon is a chemical compound that consists only of the elements carbon (C) and hydrogen (H). Hydrocarbons contain a backbone consisting of carbon atoms, called a carbon skeleton with hydrogen atoms attached to that backbone.
Hydrocarbon dew point The hydrocarbon dew point is the temperature (at a given pressure) at which the hydrocarbon components of any hydrocarbon-rich gas mixture, such as natural gas, will start to condense out of the gaseous phase. It is often also referred to as the HDP or the HCDP.
Hydrocarbons on other planets Basic hydrocarbons are ubiquitous in the atmospheres of Jupiter and Saturn. The parent molcule, methane (CH4), undergoes photochemical reactions which convert it to chain molecules such as acetylene (C2H2), ethylene (C2H4), and ethane (C2H6).
Hydrocephalus Hydrocephalus, sometimes known as Water on the Brain, is a condition in which abnormal accumulation of cerebrospinal fluid (CSF) in the brain causes increased intracranial pressure inside the skull. This is usually due to blockage of CSF outflow in the brain ventricles or in the subarachnoid space at the base of the brain.
Hydrocodone Hydrocodone or dihydrocodeinone (marketed as Vicodin, Anexsia, Dicodid, Hycodan, Hycomine, Lorcet, Lortab, Norco, Novahistex, Hydroco, Tussionex, Vicoprofen) is a semi-synthetic opioid derived from two of the naturally occurring opiates, codeine and thebaine. Hydrocodone is an orally active narcotic analgesic and antitussive.
Hydrocolloids Hydrocolloids describe certain chemicals (mostly polysaccharides and proteins) that are colloidally dispersible in water. Thus becoming effectively "soluble" they change the rheology of water by raising the viscosity and/or inducing gelation.
Hydrocotyle Hydrocotyle is a genus of aquatic or semi-aquatic plants formerly classified in the family Apiaceae, now in the family Araliaceae. At least two species are now classed as invasive aliens following introductions outside of their normal range.
Hydrocotyle ranunculoides Hydrocotyle ranunculoides , known as water pennywort or floating pennywort is an aquatic member of the Ranunculaceae. In the UK it is an invasive alien species which is currently spreading in waterways in England and Wales.
Hydrocotyle umbellata Hydrocotyle umbellata, is an aquatic, or water-loving, perennial that thrives in warm, temperate regions. Its is known as dollarweed, marsh or water pennywort or navelwort although the latter names are also used for unrelated plants such as Umbilicus rupestris.
Hydrodaktulopsychicharmonica The hydrodaktulopsychicharmonica is a type of musical instrument consisting of a series of crystal glasses made up of varying amount of water. It, or instruments like it, helped inspire Benjamin Franklin's glass harmonica.
Hydrodealkylation Hydrodealkylation is a chemical reaction that often involves reacting an aromatic hydrocarbon such as toluene in the presence of hydrogen gas to form a simpler aromatic hydrocarbon devoid of functional groups, for example, converting 1,2,4-trimethylbenzene to xylene.Free Patents Online
Hydrodesulfurization Hydrodesulfurization (HDS) is a catalytic chemical process widely used to remove sulfur (S) from natural gas and from refined petroleum products such as gasoline or petrol, jet fuel, kerosene, diesel fuel, and fuel oils.Hydrodesulfurization Technologies and Costs Nancy Yamaguchi, Trans Energy Associates, William and Flora Hewlett Foundation Sulfur Workshop, Mexico City, May 29-30, 2003 The purpose of removing the sulfur is to reduce the sulfur dioxide (SO2) emissions that result from using those fuels in automotive vehicles, aircraft, railroad locomotives, ships, gas or oil burning power plants, residential and industrial furnaces, and other forms of fuel combustion.
Hydroelectricity [upper reservoir and dam of the Ffestiniog Pumped-Storage Scheme in north Wales].The power station at the lower reservoir has four water turbines which can generate 360 megawatts of electricity within 60 seconds of the need arising.
Hydrofoil board The Foilboard is a type of surfboard equipped with a hydrofoil that extends below the board, causing the board to completely lift out of the water at high speeds. A jetski is used to pull the surfer into a wave.
Hydroformylation Hydroformylation, also known as oxo synthesis, is an important industrial process for the production of aldehydes from alkenes. This chemical reaction entails the addition of a formyl group (CHO) group and a hydrogen atom to a carbon-carbon double bond.
Hydrogel Hydrogel is a network of polymer chains that are water-soluble, sometimes found as a colloidal gel in which water is the dispersion medium. Hydrogels are superabsorbent (they can contain over 99% water) natural or synthetic polymers.
Hydrogen bond A hydrogen bond is a special type of attractive interaction that exists between an electronegative atom and a hydrogen atom bonded to another electronegative atom. This type of bond always involves a hydrogen atom, thus the name.
Hydrogen Breath Test A Hydrogen Breath Test (or HBT) is used as a clinical medical diagnosis for people with irritable bowel syndrome, and common food intolerances. The test is simple, non-invasive, and is performed after a short period of fasting (typically 8 hours).
Hydrogen carrier A hydrogen carrier is an organic macromolecule that transports atoms of hydrogen from one place to another inside a cell or from cell to cell for use in various metabolical processes. An example is NADPH in photosynthesis.
Hydrogen embrittlement Hydrogen embrittlement (or hydrogen grooving) is the process by which various metals, most importantly high-strength steel, become brittle and crack following exposure to hydrogen. Hydrogen cracking can pose an engineering problem especially in the context of a hydrogen economy.
Hydrogen fuel injection Hydrogen Fuel Injection, or HFI, is a system to reduce exhaust emissions of internal combustion engines and improve fuel economy. HFI systems work by injecting hydrogen as a combustion enhancement into the intake manifold of an internal combustion engine to achieve these benefits.
Hydrogen halide Hydrogen halides (or hydrohalic acids) are acids resulting from the chemical reaction of hydrogen with one of the halogen elements (fluorine, chlorine, bromine, iodine), which are found in group VII of the periodic table. Astatine is not included in the list because it is very rare, unstable and not found as the acid in substantial quantities.
Hydrogen highway A hydrogen highway is a chain of hydrogen-equipped filling stations and other infrastructure along a road or highway which allow hydrogen powered cars to travel. A hydrogen filling infrastructure is generally assumed to be a pre-requisite for mass utilization of hydrogen cars.
Hydrogen hypothesis The hydrogen hypothesis is a model proposed by William Martin and Miklos Muller in 1998 that describes a possible way in which the mitochondrion developed in the first eukaryotic cell within the endosymbiotic theory framework.
Hydrogen storage Hydrogen storage is the main technological problem of a viable hydrogen economy. Some attention has been given to the role of hydrogen to provide grid energy storage for unpredictable energy sources, like wind power, but most research into hydrogen storage is focussed on storing hydrogen in a lightweight, compact manner for mobile applications.
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