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  • RCA Corporation (American company)

    RCA Corporation, major American electronics and broadcasting conglomerate that is a unit of General Electric Company. Among its subsidiaries is the National Broadcasting Company (NBC). Headquarters are in New York City. RCA was founded as Radio Corporation of America by the General Electric

  • RCA Electronic Music Synthesizer (musical instrument)

    music synthesizer: The first electronic sound synthesizer, an instrument of awesome dimensions, was developed by the American acoustical engineers Harry Olson and Herbert Belar in 1955 at the Radio Corporation of America (RCA) laboratories at Princeton, New Jersey. The information was fed to the synthesizer encoded on a punched…

  • RCA in Music City, U.S.A.: The Nashville Sound

    Chet Atkins was a respected guitarist and songwriter long before he was put in charge of RCA’s office in Nashville in 1957. Most producers took their cues from the prevailing prejudices at The Grand Ole Opry, the long-running live radio show on WSM, Nashville, which networked a traditional concept

  • RCA Records (American record company)

    RCA in Music City, U.S.A.: The Nashville Sound: Chet Atkins was a respected guitarist and songwriter long before he was put in charge of RCA’s office in Nashville in 1957. Most producers took their cues from the prevailing prejudices at The Grand Ole Opry, the long-running live radio show on WSM, Nashville, which…

  • RCA Victor (American record company)

    RCA in Music City, U.S.A.: The Nashville Sound: Chet Atkins was a respected guitarist and songwriter long before he was put in charge of RCA’s office in Nashville in 1957. Most producers took their cues from the prevailing prejudices at The Grand Ole Opry, the long-running live radio show on WSM, Nashville, which…

  • RCA VideoDisc (electronic device)

    television: Video discs: The RCA VideoDisc, which superficially resembled a long-playing phonograph record, was 300 mm (12 inches) in diameter and had spiral grooves that were read by a diamond stylus. The stylus had a metal coating and moved vertically in a hill-and-dale groove etched into the disc, thereby…

  • RCAF (Cambodian military)

    Cambodia: Security: …the armed forces, called the Royal Cambodian Armed Forces (RCAF), which include the army, navy, and air force. The RCAF was created in 1993 through the merger of the Cambodian government’s military forces and the two noncommunist resistance armies; the Khmer Rouge and royalist forces were absorbed into the RCAF…

  • RCAF (Canadian military)

    Royal Canadian Air Force (RCAF), Canadian military organization in charge of that nation’s air defense. Since its inception in 1924, the RCAF has served Canadians in peace and war. It played a vital role in the Second World War, becoming the fourth-largest Allied air force, and reached its “golden

  • RCB (bank, Russia)

    Russia: Finance: The Russian Central Bank (RCB), which took over the functions of the Soviet-era Gosbank, is exclusively responsible for regulating the country’s monetary system. The bank’s primary function is to protect and stabilize the ruble, which it attempts to do through its control of foreign exchange. Under…

  • RCC (Iraqi government)

    Iraq: Constitutional framework: …but also in the party-run Revolutionary Command Council (RCC), without whose approval no law could be promulgated. Executive power rested with the president, who also served as the chairman of the RCC, supervised the cabinet ministers, and ostensibly reported to the RCC. Judicial power was also, in theory, vested in…

  • RCC (Sudanese government)

    Gaafar Mohamed el-Nimeiri: …minister and chairman of the Revolutionary Command Council (RCC). He put down a right-wing revolt led by Sayyid ?ādiq al-Mahdī in March 1970 but was briefly overthrown by a communist coup in July 1971. In September 1971 he was elected president in a plebiscite with 98.6 percent of the vote.

  • RCD (political party, Tunisia)

    Democratic Constitutional Rally, Tunisian political party that led the movement for independence from France (1956) and ruled Tunisia until 2011. The Neo-Destour was formed in 1934 by discontented young members of the more conservative Destour. After a bitter struggle with the parent organization,

  • RCHM (British conservation organization)

    art conservation and restoration: Role of law: …Great Britain, for example, the Royal Commission on Historical Monuments (RCHM) was set up in 1908, and the Civic Amenities Act of 1967 enabled local planning authorities to define special areas for “conservation and enhancement.” In France, the Commission des Secteurs Sauvegardés was set up in 1962 under André Malraux,…

  • RCM (diagnostics)

    melanoma: Diagnosis and treatment: An approach known as reflectance confocal microscopy (RCM), sometimes described as “optical biopsy,” may used to diagnosis melanoma. RCM allows doctors to examine suspicious moles and skin abnormalities without cutting into the skin. Another diagnostic approach that does not entail cutting into the skin is adhesive patch testing, in…

  • RCMP

    Royal Canadian Mounted Police (RCMP), Canada’s federal police force. It is also the provincial and criminal police establishment in all provinces except Ontario and Quebec and the only police force in the Yukon and Northwest territories. It is responsible for Canadian internal security as well.

  • RCN (Canadian military)

    Royal Canadian Navy (RCN), naval military organization of Canada, charged with the national defense at sea, protection of shipping, and fulfillment of international military agreements. Canada’s navy has defended Canadian interests in home waters and overseas since the early 20th century—despite

  • RCOOH (chemical compound)

    Carboxylic acid, any of a class of organic compounds in which a carbon (C) atom is bonded to an oxygen (O) atom by a double bond and to a hydroxyl group (―OH) by a single bond. A fourth bond links the carbon atom to a hydrogen (H) atom or to some other univalent combining group. The carboxyl (COOH)

  • RCP (British organization)

    Royal Commission on the Press (RCP), any of three groups appointed by the government of the United Kingdom in the 20th century (1947–49; 1961–62; 1974–77) to investigate the issues of press standards and concentration of ownership and to make recommendations for improvements in those areas. Their

  • RCRA (United States [1976])

    toxic waste: Laws: The Resource Conservation and Recovery Act (RCRA) became law in 1976 and regulated the safe handling and disposal of hazardous wastes, including those that occur in underground storage tanks. It created the “cradle-to-grave” (that is, from manufacture to final disposal) system to keep track of such…

  • RCT (medicine)

    evidence-based medicine: Best evidence: …generated by systematic reviews of randomized controlled trials (RCTs), which minimize bias and allow for causal interpretations of new interventions. Properly designed RCTs, in which study subjects are assigned by chance to either the new intervention or the standard treatment, themselves represent the next-most-reliable level of evidence. Below RCTs are…

  • rd (measurement)

    Rod, old English measure of distance equal to 16.5 feet (5.029 metres), with variations from 9 to 28 feet (2.743 to 8.534 metres) also being used. It was also called a perch or pole. The word rod derives from Old English rodd and is akin to Old Norse rudda (“club”). Etymologically rod is also akin

  • RDA (political party, Africa)

    flag of Benin: …had been used by the African Democratic Rally—i.e., the legislators in the French National Assembly who represented French West Africa following World War II. The colours were also associated with Ethiopia, the oldest independent African state, and with the flags of contemporaneously independent Ghana (1957 flag design), Cameroon (1957), and…

  • RDA (diet)

    therapeutics: General requirements: Recommended Dietary Allowances (RDAs), one of many sets of recommendations put out by various countries and organizations, have been established for these essential nutrients by the Food and Nutrition Board of the National Academy of Sciences. The RDAs are guidelines and not absolute minimums. Intake of less than…

  • RDC clause

    insurance: RDC clause: The RDC, or “running down” clause, provides coverage for legal liability of either the shipper or the common carrier for claims arising out of collisions. (Collision loss to the vessel itself is part of the hull coverage.) The RDC clause covers negligence of…

  • RDD (weapon)

    Dirty bomb, explosive device designed to scatter radioactive material, hence the adjective dirty. Unlike an atomic bomb’s explosive power, which comes from a nuclear chain reaction, the explosive energy of the dirty bomb comes from ordinary conventional explosives such as dynamite or TNT. When the

  • RDF (physics)

    liquid: Molecular structure of liquids: …potential function, u, and the radial distribution function, g. The pair potential gives information about the energy due to the interaction of a pair of molecules and is a function of the distance r between their centres. Information about the structure or the distances between pairs of molecules is contained…

  • RDF site summary (computer science)

    RSS, format used to provide subscribers with new content from frequently updated Web sites. An RSS feed is a set of instructions residing on the computer server of a Web site, which is given upon request to a subscriber’s RSS reader, or aggregator. The feed tells the reader when new material—such

  • Rdio (music-streaming service)

    Janus Friis: Later ventures: In 2010 they created Rdio, a subscription-based music-streaming service. Rdio struggled, however, and in 2015 it was agreed that the service’s key assets would be sold to competitor Pandora for some $75 million. As part of the deal, Rdio also filed for bankruptcy protection. Friis’s later ventures included Starship…

  • rdo-rje (Buddhist ritual object)

    Vajra, five-pronged ritual object extensively employed in Tibetan Buddhist ceremonies. It is the symbol of the Vajrayāna school of Buddhism. Vajra, in Sanskrit, has both the meanings of “thunderbolt” and “diamond.” Like the thunderbolt, the vajra cleaves through ignorance. The thunderbolt was

  • RDR (political party, C?te d’Ivoire)

    C?te d'Ivoire: Return to normalcy: Also in 2018, Ouattara’s RDR and most of the other parties in the ruling RHDP coalition agreed to transform the coalition into a new party. Bédié’s PDCI rejected the proposal, however, largely because the RDR had dismissed the PDCI’s insistence that it was the PDCI’s turn to field the…

  • RDS-220 (Soviet thermonuclear bomb)

    Tsar Bomba, (Russian: “King of Bombs”) Soviet thermonuclear bomb that was detonated in a test over Novaya Zemlya island in the Arctic Ocean on October 30, 1961. The largest nuclear weapon ever set off, it produced the most powerful human-made explosion ever recorded. The bomb was built in 1961 by a

  • RDS-37 (thermonuclear bomb)

    nuclear weapon: Thermonuclear weapons: Known in the West as Joe-19 and RDS-37 in the Soviet Union, the thermonuclear bomb was dropped from a bomber at the Semipalatinsk (now Semey, Kazakhstan) test site. As recounted by Sakharov, this test “crowned years of effort [and] opened the way for a whole range of devices with remarkable…

  • RDS-6 (thermonuclear bomb)

    nuclear weapon: Thermonuclear weapons: …known in the West as Joe-4 and in the Soviet Union as RDS-6, was detonated on August 12, 1953, with a yield of 400 kilotons. Significantly, it was a deliverable thermonuclear bomb—a milestone that the United States would not reach until May 20, 1956—and also the first use of solid…

  • RDX (explosive)

    RDX, powerful explosive, discovered by Georg Friedrich Henning of Germany and patented in 1898 but not used until World War II, when most of the warring powers introduced it. Relatively safe and inexpensive to manufacture, RDX was produced on a large scale in the United States by a secret process

  • Re (Egyptian god)

    Re, in ancient Egyptian religion, god of the sun and creator god. He was believed to travel across the sky in his solar bark and, during the night, to make his passage in another bark through the underworld, where, in order to be born again for the new day, he had to vanquish the evil serpent

  • Re (chemical element)

    Rhenium (Re), chemical element, a very rare metal of Group 7 (VIIb) of the periodic table and one of the densest elements. Predicted by the Russian chemist Dmitry Ivanovich Mendeleyev (1869) as chemically related to manganese, rhenium was discovered (1925) by the German chemists Ida and Walter

  • Re He (river, China)

    Chengde: …northeast of Beijing, on the Re River (Re He; “Hot River”), a small tributary of the Luan River. The Re River, so called because of the various hot springs that discharge into it above Chengde, gave its name to the city and to the province of which the city was…

  • Ré Island (island, France)

    Ré Island, island in the Bay of Biscay, Charente-Maritime département, Poitou-Charentes région of France. It is located off the west coast of France, opposite La Pallice and La Rochelle. It was for long separated from the mainland by the shallow water of Pertuis Breton, 2 miles (3.2 km) wide at the

  • Re Magi chapel (chapel, Rome, Italy)

    Francesco Borromini: Later years and influence: For the Re Magi chapel in the Collegio di Propaganda Fide, on which he worked until his death, he designed six pairs of colossal pilasters to define a generally rectangular space with bevelled corners.

  • Re River (river, China)

    Chengde: …northeast of Beijing, on the Re River (Re He; “Hot River”), a small tributary of the Luan River. The Re River, so called because of the various hot springs that discharge into it above Chengde, gave its name to the city and to the province of which the city was…

  • Re-Atum (Egyptian god)

    Re, in ancient Egyptian religion, god of the sun and creator god. He was believed to travel across the sky in his solar bark and, during the night, to make his passage in another bark through the underworld, where, in order to be born again for the new day, he had to vanquish the evil serpent

  • re-designation rate (education)
  • Re-elect the President, Committee to (U.S. politics)

    Watergate scandal: Burglary, arrest, and limited immediate political effect: …the security chief of the Committee to Re-elect the President (later known popularly as CREEP), which was presided over by John Mitchell, Nixon’s former attorney general. The arrest was reported in the next morning’s Washington Post in an article written by Alfred E. Lewis, Carl Bernstein, and Bob

  • Re-Harakhte (Egyptian god)

    ancient Egyptian religion: The Gods: …were Khepri (the morning form), Re-Harakhty (a form of Re associated with Horus), and Atum (the old, evening form). There were three principal “social” categories of deity: gods, goddesses, and youthful deities, mostly male.

  • Re-Harakhty (Egyptian god)

    ancient Egyptian religion: The Gods: …were Khepri (the morning form), Re-Harakhty (a form of Re associated with Horus), and Atum (the old, evening form). There were three principal “social” categories of deity: gods, goddesses, and youthful deities, mostly male.

  • re-photography (art)

    Sherrie Levine: …either through photographic reproductions (termed re-photography), drawing, watercolour, or sculpture. Her appropriations are conceptual gestures that question the Modernist myths of originality and authenticity. She held that the loss of authenticity in art was a result of the ubiquitous mediated signs that defined contemporary reality and that it was impossible…

  • re-sequencing (genetics)

    whole genome sequencing: Next-generation technologies: …technologies originally were designed to re-sequence genomes (as opposed to de novo sequencing). In re-sequencing, short sequences are produced and aligned computationally to existing reference genome sequences generated, at least initially, using the older de novo sequencing methods. Next-generation sequencing approaches are characterized generally by the massively parallel production of…

  • Re-united National Party (political party, South Africa)

    National Party (NP), South African political party, founded in 1914, which ruled the country from 1948 to 1994. Its following included most of the Dutch-descended Afrikaners and many English-speaking whites. The National Party was long dedicated to policies of apartheid and white supremacy, but by

  • Re: Creation (poetry by Giovanni)

    Nikki Giovanni: … (1968), Black Judgement (1968), and Re: Creation (1970), her content was urgently revolutionary and suffused with deliberate interpretation of experience through a black consciousness.

  • REA (United States agency)

    United States: Agricultural recovery: …creation in 1935 of the Rural Electrification Administration (REA), which did more to bring farmers into the 20th century than any other single act. Thanks to the REA, nine out of 10 farms were electrified by 1950, compared to one out of 10 in 1935.

  • REA Express, Inc. (American company)

    REA Express, Inc., American company that at one time operated the nation’s largest ground and air express services, transporting parcels, money, and goods, with pickup and delivery. American Railway Express Company was established by the U.S. government in 1918, during World War I, at the same time

  • Rea, Stephen (actor)

    Brian Friel: …1980 Friel cofounded (with actor-director Stephen Rea) the Field Day Theatre Company in Londonderry, Northern Ireland, and in 1983 the company began publishing pamphlets, and later anthologies, aimed at the academic community on a wide variety of historical, cultural, and artistic topics. He was elected Saoi of Aosdána, Ireland’s highest…

  • reabsorption (biology)

    excretion: Mammals: …formation involves three processes: filtration, reabsorption, and secretion. Primary urine is formed by filtration from the blood. From this primary urine certain substances are reabsorbed into the blood and other substances are secreted into the primary urine from the blood. The word secretion is used by renal physiologists to imply…

  • Reaching for the Moon (film by Goulding [1930])

    Edmund Goulding: The 1930s: …The Devil’s Holiday (1930) and Reaching for the Moon (1930), the latter an ur-screwball comedy starring Douglas Fairbanks as a Wall Street millionaire who courts an aviator (Bebe Daniels) during an ocean voyage. The Night Angel (1931) came next, but it was Grand Hotel (1932) that established Goulding as one…

  • reactance (electronics)

    Reactance, in electricity, measure of the opposition that a circuit or a part of a circuit presents to electric current insofar as the current is varying or alternating. Steady electric currents flowing along conductors in one direction undergo opposition called electrical resistance, but no

  • reactant (chemistry)

    chemical reaction: …one or more substances, the reactants, are converted to one or more different substances, the products. Substances are either chemical elements or compounds. A chemical reaction rearranges the constituent atoms of the reactants to create different substances as products.

  • reaction

    Chemical reaction, a process in which one or more substances, the reactants, are converted to one or more different substances, the products. Substances are either chemical elements or compounds. A chemical reaction rearranges the constituent atoms of the reactants to create different substances as

  • reaction blading (technology)

    turbine: Blading design: …of perfection: impulse blading and reaction blading. The principle of impulse blading is illustrated in the schematic diagram of Figure 1 for a first stage. A series of stationary nozzles allows the steam to expand to a lower pressure while its velocity and kinetic energy increase. The steam is then…

  • reaction bonding

    advanced ceramics: Reaction sintering: Reaction sintering, or reaction bonding, is an important means of producing dense covalent ceramics. Reaction-bonded silicon nitride (RBSN) is made from finely divided silicon powders that are formed to shape and subsequently reacted in a mixed nitrogen/hydrogen or nitrogen/helium atmosphere at 1,200 to…

  • reaction center (biochemistry)

    Robert Huber: …a protein complex (called a photosynthetic reaction centre) that is essential to photosynthesis in certain bacteria. By 1985 the three scientists had succeeded in describing the complete atomic structure of the protein. Although bacterial photosynthesis is somewhat simpler than that carried on by plants, the scientists’ work significantly increased the…

  • reaction centre (biochemistry)

    Robert Huber: …a protein complex (called a photosynthetic reaction centre) that is essential to photosynthesis in certain bacteria. By 1985 the three scientists had succeeded in describing the complete atomic structure of the protein. Although bacterial photosynthesis is somewhat simpler than that carried on by plants, the scientists’ work significantly increased the…

  • reaction cross section (physics)

    Cross section, in nuclear or subatomic particle physics, probability that a given atomic nucleus or subatomic particle will exhibit a specific reaction (for example, absorption, scattering, or fission) in relation to a particular species of incident particle. Cross section is expressed in terms of

  • reaction dynamics (chemistry)

    chemical kinetics: Molecular dynamics: The second theoretical approach to chemical kinetics is referred to as molecular dynamics, or reaction dynamics. It is a more detailed treatment of reactions and is designed to investigate the atomic motions that occur during a chemical reaction and the quantum states of…

  • reaction formation (psychology)

    defense mechanism: Reaction formation is the fixation in consciousness of an idea, affect, or desire that is opposite to a feared unconscious impulse. A mother who bears an unwanted child, for example, may react to her feelings of guilt for not wanting the child by becoming extremely…

  • reaction injection molding (materials processing)

    major industrial polymers: Polyurethane elastomers: This technology, known as reaction injection molding, accounts for much of the production of thermosetting elastomers made from polyurethane. Polyurethane elastomers are made into automobile parts, industrial rollers, flexible molds, forklift tires, roller-skate and skateboard wheels, medical equipment, and shoe soles.

  • reaction intermediate (chemistry)

    Chemical intermediate, any chemical substance produced during the conversion of some reactant to a product. Most synthetic processes involve transformation of some readily available and often inexpensive substance to some desired product through a succession of steps. All the substances generated

  • reaction mechanism

    Reaction mechanism, in chemical reactions, the detailed processes by which chemical substances are transformed into other substances. The reactions themselves may involve the interactions of atoms, molecules, ions, electrons, and free radicals, and they may take place in gases, liquids, or

  • reaction order (chemistry)

    reaction mechanism: Kinetic order: Because the possibilities that need to be considered for the transition state have been limited by determination of the chemical structures of the participants, the most powerful method of obtaining further information is the use of the kinetic method—i.e., the study of the…

  • reaction rate (chemistry)

    Reaction rate, the speed at which a chemical reaction proceeds. It is often expressed in terms of either the concentration (amount per unit volume) of a product that is formed in a unit of time or the concentration of a reactant that is consumed in a unit of time. Alternatively, it may be defined

  • reaction rim (mineralogy)

    mineral: Mineral associations and phase equilibrium: …presence (or absence) of a reaction rim, which is a region separating two or more minerals and consisting of the products of a reaction between them. The absence of any observable reaction rims between minerals that physically touch each other suggests that they were in equilibrium at the time when…

  • reaction sintering

    advanced ceramics: Reaction sintering: Reaction sintering, or reaction bonding, is an important means of producing dense covalent ceramics. Reaction-bonded silicon nitride (RBSN) is made from finely divided silicon powders that are formed to shape and subsequently reacted in a mixed nitrogen/hydrogen or nitrogen/helium atmosphere at 1,200 to…

  • reaction staging (engineering)

    turbine: Turbine staging: Reaction staging is similar to pressure staging, except that a greater number of reaction stages are required. The first turbine stage, however, is often an impulse stage for controlling the steam flow and for rapidly reducing the pressure in stationary nozzles from its high steam…

  • reaction texture (geology)

    igneous rock: Important textural types: Reaction textures occur at the corroded margins of crystals, from the corrosive rimming of crystals of one mineral by finer-grained aggregates of another, or as a result of other features that indicate partial removal of crystalline material by reaction with magma or other fluid.

  • reaction time (psychological measurement)

    human behaviour: Central nervous system processing: …show a tendency toward decreasing speed of response. This is a gradual change occurring across the entire life span that shows up in a variety of so-called speeded tasks (those in which errors would be unlikely if the individual had an unlimited amount of time to complete the tasks). For…

  • reaction time assay (biochemistry)

    vitamin: Animal assay: In a reaction time assay, an animal is first deprived of a vitamin until a specific deficiency symptom appears; then the animal is given a known amount of a food extract containing the vitamin, and the deficiency symptom disappears within a day or two. The time required…

  • reaction turbine (technology)

    turbine: Reaction turbines: In a reaction turbine, forces driving the rotor are achieved by the reaction of an accelerating water flow in the runner while the pressure drops. The reaction principle can be observed in a rotary lawn sprinkler where the emerging jet drives the rotor…

  • reaction wood (plant anatomy)

    tree: Adaptations: In branches, reaction tissue forms where its inherent reaction force (pushing in the case of conifers and pulling in the case of hardwoods) will restore the intrinsic growth direction (equilibrium, or initial, position). This defines the locus of reaction tissue irrespective of the orientation of the structure…

  • reaction, enthalpy of (chemical reaction)

    heat of reaction: …pressure is also designated the enthalpy of reaction, represented by the symbol ΔH. If the heat of reaction is positive, the reaction is said to be endothermic; if negative, exothermic.

  • reaction, heat of (chemistry)

    Heat of reaction, the amount of heat that must be added or removed during a chemical reaction in order to keep all of the substances present at the same temperature. If the pressure in the vessel containing the reacting system is kept at a constant value, the measured heat of reaction also

  • reaction, law of (physics)

    mechanics: Centre of mass: …the orbit, but, according to Newton’s third law, it must actually be accelerated by a force due to Earth that is equal and opposite to the force that the Sun exerts on Earth. In other words, considering only the Sun and Earth (ignoring, for example, all the other planets), if…

  • reaction-bonded silicon carbide (ceramics)

    advanced ceramics: Reaction sintering: Reaction-bonded silicon carbide (RBSC) is produced from a finely divided, intimate mixture of silicon carbide and carbon. Pieces formed from this mixture are exposed to liquid or vapour silicon at high temperature. The silicon reacts with the carbon to form additional silicon carbide, which bonds…

  • reaction-bonded silicon nitride (ceramics)

    advanced ceramics: Reaction sintering: Reaction-bonded silicon nitride (RBSN) is made from finely divided silicon powders that are formed to shape and subsequently reacted in a mixed nitrogen/hydrogen or nitrogen/helium atmosphere at 1,200 to 1,250 °C (2,200 to 2,300 °F). The nitrogen permeates the porous body and reacts with the…

  • reaction-rate constant (chemistry)

    reaction rate: The rate constant, or the specific rate constant, is the proportionality constant in the equation that expresses the relationship between the rate of a chemical reaction and the concentrations of the reacting substances. The measurement and interpretation of reactions constitute the branch of chemistry known as…

  • reactionary movement (sociology)

    social movement: Types of social movements: A reactionary movement advocates the restoration of a previous state of social affairs, while a progressive movement argues for a new social arrangement. A conservative movement opposes the changes proposed by other movements, or those seeming to develop through cultural drift, and advocates preservation of existing…

  • reactions, cycle of (chemistry)

    chemical kinetics: Composite reaction mechanisms: …of reactions is called a cycle of reactions, and it can occur a number of times, in which case the reaction is referred to as a chain reaction. The two reactions in which bromine is regenerated are known as the chain-propagating steps. The average number of times the pair of…

  • reactive armour (military technology)

    armoured vehicle: Fully tracked carriers: …with metal cages and with reactive armour that exploded outward to provide better protection against improvised explosive devices and rocket-propelled grenades.

  • reactive arthritis (pathology)

    Reiter syndrome, disorder characterized by arthritis and sometimes inflammation of the eye, urogenital tract, or mucous membranes that is typically triggered by a sexually transmitted disease or a gastrointestinal infection. Presumably, Reiter syndrome reflects an aberrant immune response to

  • reactive dye (chemistry)

    Reactive dye, any of a class of highly coloured organic substances, primarily used for tinting textiles, that attach themselves to their substrates by a chemical reaction that forms a covalent bond between the molecule of dye and that of the fibre. The dyestuff thus becomes a part of the fibre and

  • reactive genotoxic carcinogen (biochemistry)

    poison: Carcinogenesis: They are either direct-acting or indirect-acting chemicals.

  • reactive ion etching (finishing process)

    integrated circuit: Etching: …with strong chemicals or by reactive ion etching (RIE). RIE is like sputtering in the argon chamber, but the polarity is reversed and different gas mixtures are used. The atoms on the surface of the wafer fly away, leaving it bare.

  • reactive oxygen species (biochemistry)

    aging: Oxidative damage theory: …particular with molecules known as reactive oxygen species (ROS). This theory was first proposed in the 1950s by American gerontologist Denham Harman and was supported in part by evidence that antioxidant proteins, which neutralize free radicals, are more abundant in aging cells, indicating a response to oxidative stress.

  • reactive regionalism (economics)

    economic integration: Reactive regionalism: Reactive regionalism is also referred to as defensive regionalism, suggesting that states choose to pursue economic integration to protect their shared interests from a specific or nebulous external threat. In a historical context, reactive regionalism was viewed by developing countries as a technique…

  • reactive vapour-phase glassmaking (technology)

    industrial glass: From the gaseous state: In another process, known as reactive vapour-phase glassmaking, the desired glass is formed by a chemical reaction. Chemical vapour deposition, or CVD, belongs to this latter category, with a good example being the making of silica glass by hydroxylation. In the hydroxylation technique, vapours of silicon tetrachloride (SiCl4) are reacted…

  • reactive waste

    hazardous-waste management: Hazardous-waste characteristics: Reactive wastes are chemically unstable and react violently with air or water. They cause explosions or form toxic vapours. Ignitable wastes burn at relatively low temperatures and may cause an immediate fire hazard. Corrosive wastes include strong acidic or alkaline substances. They destroy solid material…

  • reactive-liquid sintering (chemistry)

    advanced ceramics: Solid-state sintering: In reactive-liquid, or transient-liquid, sintering, a chemical additive produces a temporary liquid that facilitates the initial stages of sintering. The liquid is subsequently evaporated, resorbed by the solid particles, or crystallized into a solid.

  • reactivity (nuclear reactor)

    nuclear reactor: Reactor control: …in the nuclear industry is reactivity, which is a measure of the state of a reactor in relation to where it would be if it were in a critical state. Reactivity is positive when a reactor is supercritical, zero at criticality, and negative when the reactor is subcritical. Reactivity may…

  • reactivity (chemistry)

    heterocyclic compound: The nature of heteroaromaticity: Chemical reactivity can provide a certain qualitative insight into aromaticity. The reactivity of an aromatic compound is affected by the extra stability of the conjugated system that it contains; the extra stability in turn determines the tendency of the compound to react by substitution of…

  • reactivity, chemical (chemistry)

    heterocyclic compound: The nature of heteroaromaticity: Chemical reactivity can provide a certain qualitative insight into aromaticity. The reactivity of an aromatic compound is affected by the extra stability of the conjugated system that it contains; the extra stability in turn determines the tendency of the compound to react by substitution of…

  • reactor (chemistry)

    Reactor, in chemical engineering, device or vessel within which chemical processes are carried out for experimental or manufacturing purposes. Reactors range in size and complexity from small, open kettles fitted with simple stirrers and heaters to large, elaborate vessels equipped with jackets or

  • reactor (device)

    Nuclear reactor, any of a class of devices that can initiate and control a self-sustaining series of nuclear fissions. Nuclear reactors are used as research tools, as systems for producing radioactive isotopes, and most prominently as energy sources for nuclear power plants. Nuclear reactors

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