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  • Invisible Stripes (film by Bacon [1939])

    Lloyd Bacon: Warner Brothers: Invisible Stripes (1939) was better. The drama featured George Raft as an ex-convict who tries to keep his kid brother (William Holden) from hooking up with his erstwhile partner (Bogart). Bacon returned to melodrama with Three Cheers for the Irish (1940), which starred Thomas Mitchell…

  • Invisible Theatre (theatrical form)

    Augusto Boal: Invisible Theatre involves actors performing a written and rehearsed problematic situation in a public place in order to provoke responses from passersby, who are unaware that they are taking part in theatre. In Forum Theatre, actors perform a short scene based on an event involving…

  • invisible trade (economics)

    Invisible trade, in economics, the exchange of physically intangible items between countries. Invisible trade can be distinguished from visible trade, which involves the export, import, and reexport of physically tangible goods. Basic categories of invisible trade include services (receipts and

  • Invisible Woman (comic-book character)

    Fantastic Four: Origins: Reed Richards, a pompous scientist; Sue Storm, his lovely and somewhat reserved fiancée; Sue’s hotheaded teenaged brother Johnny Storm; and Richards’s beefy longtime friend pilot Ben Grimm. The foursome commandeered an untested spaceship of Richards’s design from the U.S. military in a frantic but unsanctioned effort to beat the Soviets…

  • Invisible Woman, The (film by Fiennes [2013])

    Ralph Fiennes: In his second directorial feature, The Invisible Woman (2013), Fiennes portrayed Charles Dickens, who, at the height of his career, begins a clandestine affair with a young actress. He then helmed The White Crow (2018), a biopic about the Russian ballet dancer Rudolf Nureyev, who defected to France in 1961.…

  • Invitation to a Beheading (novel by Nabokov)

    Invitation to a Beheading, anti-utopian novel by Vladimir Nabokov, published serially in Russian as Priglasheniye na kazn from 1935 to 1936 and in book form in 1938. It is a stylistic tour de force. The novel is set in a mythical totalitarian country and presents the thoughts of Cincinnatus, a

  • Invitation to the Waltz (work by Lehmann)

    Rosamond Nina Lehmann: Invitation to the Waltz (1932) is a slight, but wholly realized, work about a girl’s timid confrontation with social demands. The girl appears again, this time in an affair with a married man, in The Weather in the Streets (1936).

  • Invitation, The (work by Castillo)

    Ana Castillo: …she published a second chapbook, The Invitation, in which female speakers describe the experience of the erotic. Castillo’s work draws on the sometimes contradictory political influences of militant ethnic and economic struggles and feminist and lesbian perspectives. Women Are Not Roses (1984), for example, explores the difficulties of poor and…

  • Invitée, L’? (work by Beauvoir)

    Simone de Beauvoir: L’Invitée (1943; She Came To Stay) describes the subtle destruction of a couple’s relationship brought about by a young girl’s prolonged stay in their home; it also treats the difficult problem of the relationship of a conscience to “the other,” each individual conscience being fundamentally a predator…

  • invocation (prosody)

    Invocation, a convention of classical literature and of epics in particular, in which an appeal for aid (especially for inspiration) is made to a muse or deity, usually at or near the beginning of the work. Homer’s Odyssey, for instance, begins The word is from the Latin invocatio, meaning “to

  • Invocation of My Demon Brother (film by Anger [1969])

    Kenneth Anger: Invocation of My Demon Brother (1969) featured scenes of occult practice mixed with documentary footage and rock-and-roll performances; its synthesizer soundtrack was composed and performed by Mick Jagger. The film was created from footage not used in Anger’s next major endeavour, Lucifer Rising, which was…

  • involuntary muscle (anatomy)

    Smooth muscle, muscle that shows no cross stripes under microscopic magnification. It consists of narrow spindle-shaped cells with a single, centrally located nucleus. Smooth muscle tissue, unlike striated muscle, contracts slowly and automatically. It constitutes much of the musculature of

  • involuntary unemployment (Keynesian economics)

    economic stabilizer: Involuntary unemployment: Another possible cause of a general depression was suggested by Keynes. It may be approached in a highly simplified way by lumping all occupations together into one labour market and all goods and services together into a single commodity market. The aggregative system…

  • involute (geometry)

    Involute, of a curve C, a curve that intersects all the tangents of the curve C at right angles. To construct an involute of a curve C, use may be made of the so-called string property. Let one end of a piece of string of fixed length be attached to a point P on the curve C and let the string be

  • involution (anthropological and economic theory)

    social change: One-directional change: …Clifford Geertz has called “involution,” found in some agrarian societies when population growth is coupled with a decrease in per capita wealth. Yet another change may be a shift from one pole to the other of a continuum—from religious to secular ways of thinking, for example. Such a change…

  • Involution Ocean (novel by Sterling)

    Bruce Sterling: His first novel, Involution Ocean (1977), describes a dystopian planet where inhabitants escape their confusing lives through drug abuse. The characters in The Artificial Kid (1980) struggle to gain stability in a world of fast-paced change.

  • Inwaer the Boneless (Viking chieftain)

    Ivar the Boneless, Viking chieftain, of Danish origin, whose life story is suffused with legend. He is best known for his exploits on the British Isles, most notably his invasion, in the company of two brothers, of several Anglo-Saxon kingdoms. Unlike previous Viking raiders who came only to

  • Inward Animal, The (work by Tiller)

    Terence Tiller: Of his major poetry collections, The Inward Animal (1943) and especially Unarm, Eros (1947) contain his most highly acclaimed poems, noted for their strong formal pattern, heraldic imagery, and striking sensuousness. Later volumes include Reading a Medal (1957), Notes for a Myth (1968), and That Singing Mesh (1979).

  • inward dive (sport)

    diving: In the fourth group, the inward dives, the diver stands on the edge of the platform and springs backward but rotates forward, again toward the board. The fifth classification is that of the twisting dives, in which the diver rotates the body on its long axis while performing one of…

  • Inward Light (religious concept and movement)

    Inner Light, the distinctive theme of the Society of Friends (Quakers), the direct awareness of God that allows a person to know God’s will for him. It was expressed in the 17th century in the teachings of George Fox, founder of the Friends, who had failed to find spiritual truth in the English c

  • inward rectifier channel (biology)

    nervous system: Potassium channels: …of potassium channel is the anomalous, or inward, rectifier channel (IIR). This channel closes with depolarization and opens with hyperpolarization. By allowing an unusual inward diffusion of K+, the IIR channel prolongs depolarization of the neuron and helps produce long-lasting nerve impulses.

  • INXS (Australian rock band)

    Mark Burnett: …lead singer of the band INXS; The Contender (2005–09), which followed a group of young boxers as they competed against one another; Are You Smarter Than a 5th Grader? (2007– ), a game show hosted by comedian Jeff Foxworthy where the contestant had to correctly answer questions typical of elementary-school…

  • Inyangani, Mount (mountain peak, Zimbabwe)

    Zimbabwe: Relief: …8,504 feet (2,592 metres) at Mount Inyangani, the highest point in Zimbabwe, in the eastern highlands. This ridge is known as the Highveld and comprises about 25 percent of the country’s total area. On each side of this central spine, sloping down northward to the Zambezi River and southward to…

  • Inylchek Glacier (glacier, Asia)

    Tien Shan: Glaciation: …in the Tien Shan is Engil’chek (Inylchek) Glacier, which is approximately 37 miles (60 km) long; it descends from the western slopes of the Khan T?ngiri massif and branches into numerous tributaries. Other large glaciers in this area include North Engil’chek (24 miles [39 km]) and one at Muzat Pass…

  • inyoite (mineral)

    Inyoite, a colourless and transparent borate mineral (CaB3O3(OH)5·4H2O) that occurs as massive granular or sperulitic aggregates in borate deposits. The structure of the mineral consists of two BO2(OH)2 tetrahedrons and a BO2OH triangle linked by calcium and hydroxyl-hydrogen bonds. Inyoite alters

  • Inzest-Motiv in Dichtung and Sage, Das (work by Rank)

    Otto Rank: …Birth of the Hero) and Das Inzest-Motiv in Dichtung und Sage (1912; “The Incest Motif in Poetry and Saga”), in which he attempted to show how the Oedipus complex supplies abundant themes for poetry and myth.

  • Inzikhistn, Di (American literary group)

    Jacob Glatstein: …in 1920 helped establish the Inzikhist (“Introspectivist”) literary movement. In later years he was one of the outstanding figures in mid-20th-century American Yiddish literature.

  • Io (satellite of Jupiter)

    Io, innermost of the four large moons (Galilean satellites) discovered around Jupiter by the Italian astronomer Galileo in 1610. It was probably also discovered independently that same year by the German astronomer Simon Marius, who named it after Io of Greek mythology. Io is the most volcanically

  • Io (Greek mythology)

    Io, in Greek mythology, daughter of Inachus (the river god of Argos) and the Oceanid Melia. Under the name of Callithyia, Io was regarded as the first priestess of Hera, the wife of Zeus. Zeus fell in love with her and, to protect her from the wrath of Hera, changed her into a white heifer. Hera

  • Iō Island (island, Japan)

    Iwo Jima, island that is part of the Volcano Islands archipelago, far southern Japan. The island has been widely known as Iwo Jima, its conventional name, since World War II (1939–45). However, Japan officially changed the name to its Japanese form, Iō-tō (Iō Island), in 2007. Iwo Jima lies in the

  • Iō Jima (island, Japan)

    Iwo Jima, island that is part of the Volcano Islands archipelago, far southern Japan. The island has been widely known as Iwo Jima, its conventional name, since World War II (1939–45). However, Japan officially changed the name to its Japanese form, Iō-tō (Iō Island), in 2007. Iwo Jima lies in the

  • io moth (insect)

    saturniid moth: The io moth (Automeris io) is characterized by yellow males and red-brown females, and both sexes have a large, dark eyespot on each hindwing. The bright green caterpillars are 5–8 cm (2–3 inches) in length and have red and white stripes running along the sides of…

  • Iō-tō (island, Japan)

    Iwo Jima, island that is part of the Volcano Islands archipelago, far southern Japan. The island has been widely known as Iwo Jima, its conventional name, since World War II (1939–45). However, Japan officially changed the name to its Japanese form, Iō-tō (Iō Island), in 2007. Iwo Jima lies in the

  • Ioanesi (river, Russia)

    Yenisey River, river of central Russia, one of the longest rivers in Asia. The world’s sixth largest river in terms of discharge, the Yenisey runs from south to north across the great expanse of central Siberia. It traverses a vast region of strikingly varied landscapes where ancient peoples and

  • Ioann (Russian religious leader)

    Ioann, (IVAN MATVEYEVICH SNYCHEV), Russian Orthodox archbishop and metropolitan of St. Petersburg and Ladoga, 1990-95, whose extreme nationalist statements were criticized as xenophobic and anti-Semitic (b. Oct. 9, 1927--d. Nov. 2,

  • Ioanna, Queen (Bulgarian royal)

    Queen Ioanna, (Giovanna Elisabetta Antonia Romana Maria), Bulgarian royal (born Nov. 13, 1907, Rome, Italy—died Feb. 26, 2000, Estoril, Port.), as the daughter of the last king of Italy, Victor Emmanuel III; the wife of King Boris III of Bulgaria; and the mother of Bulgaria’s last king, Simeon I

  • Ioannidis, Demetrios (Greek military officer)

    Dimitrios Ioannidis, Greek military officer (born March 13, 1923, Athens, Greece—died Aug. 16, 2010, Athens), was a leading figure in the Greek military junta (1967–74), which imposed a repressive government and established censorship, exile of political opponents, and the torture of dissenters; he

  • Ioannidis, Dimitrios (Greek military officer)

    Dimitrios Ioannidis, Greek military officer (born March 13, 1923, Athens, Greece—died Aug. 16, 2010, Athens), was a leading figure in the Greek military junta (1967–74), which imposed a repressive government and established censorship, exile of political opponents, and the torture of dissenters; he

  • Ioánnina (Greece)

    Ioánnina, city and dímos (municipality), periféreia (region) of Epirus (Modern Greek: ípeiros), northwestern Greece. It is located on a plateau on the western side of Lake Ioánnina (ancient Pambotis), facing the gray limestone mass of Mount Mitsikéli. Ioánnina was first mentioned in ecclesiastical

  • Ioannou, Yorgos (Greek author)

    Greek literature: Literature after 1922: Yórgos Ioánnou’s part-fictional, part-autobiographical short prose pieces present a vivid picture of life in Thessaloníki (Salonika) and Athens from the 1930s to the 1980s.

  • Ioasaf (Greek hermit)

    Metéora: …king’s son and the hermit Ioasaf, a pupil of Athanasios, enlarged the Metéoron, making it the wealthiest and most prominent monastery in the area. In the period of Ottoman rule over Greece (1453–1832), the sultans left the Orthodox religion intact, and the monastic communities at Metéora thrived; several more monasteries…

  • Iobates (Greek mythology)

    Bellerophon: Proetus then sent Bellerophon to Iobates, the king of Lycia, with a message that he was to be slain. That king sent him against some dangerous antagonists, but since he always triumphed, the king finally recognized Bellerophon as more than human and married him to his daughter. Bellerophon lived in…

  • IOC

    International Olympic Committee, organization formed in Paris in 1894 to conduct, promote, and regulate the modern Olympic Games

  • Iocaste (Greek mythology)

    Martha Graham: Maturity: …about the Greek legendary figure Jocasta, the whole dance-drama takes place in the instant when Jocasta learns that she has mated with Oedipus, her own son, and has borne him children. The work treats Jocasta rather than Oedipus as the tragic victim, and shows her reliving the events of her…

  • IOCU (international organization)

    Consumers International (CI), international consortium of consumer-advocacy groups that promotes the rights and interests of consumers. CI was founded as the International Organisation of Consumers Unions (IOCU) in 1960 and by the early 21st century had grown to include more than 200 member

  • ioculare (medieval entertainer)

    Proven?al literature: Origins and development: …contemporary Latin chroniclers, who mentioned ioculares, men of a class not highly regarded, whose profession consisted in amusing their audience by jugglers’ tricks, by exhibiting performing animals, or by recitation and song. These performers were called joglars in Proven?al and jongleurs in French. From among them rose the troubadours, who…

  • iodate mineral

    nitrate and iodate minerals: iodate minerals, small group of naturally occurring inorganic compounds that are practically confined to the Atacama Desert of northern Chile; the principal locality is Antofagasta. These minerals occur under the loose soil as beds of grayish caliche (a hard cemented mixture of nitrates, sulfates, halides,…

  • iodide (chemical compound)

    halogen: Oxidation: chlorides, bromides, iodides, and astatides. Many of the halides may be considered to be salts of the respective hydrogen halides, which are colourless gases at room temperature and atmospheric pressure and (except for hydrogen fluoride) form strong acids in aqueous solution. Indeed, the general term salt is…

  • iodide ion (chemical compound)

    iodine: Physical and chemical properties: Although the iodide ion is colourless, iodide solutions may acquire a brownish tint as a result of oxidation of iodide to free iodine by atmospheric oxygen. Molecules of elemental iodine, consisting of two atoms (I2), combine with iodides to form polyiodides (typically I2 + I? → I?3),…

  • iodine (chemical element)

    Iodine (I), chemical element, a member of the halogen elements, or Group 17 (Group VIIa) of the periodic table. atomic number 53 atomic weight 126.9044 melting point 113.5 °C (236 °F) boiling point 184 °C (363 °F) specific gravity 4.93 at 20 °C (68 °F) oxidation states ?1, +1, +3, +5, +7 electron

  • iodine deficiency (pathology)

    Iodine deficiency, condition in which iodine is insufficient or is not utilized properly. Iodine is an element that directly affects thyroid gland secretions, which themselves to a great extent control heart action, nerve response to stimuli, rate of body growth, and metabolism. Iodine is essential

  • iodine number (chemistry)

    Iodine value, in analytical chemistry, measure of the degree of unsaturation of an oil, fat, or wax; the amount of iodine, in grams, that is taken up by 100 grams of the oil, fat, or wax. Saturated oils, fats, and waxes take up no iodine; therefore their iodine value is zero; but unsaturated o

  • iodine value (chemistry)

    Iodine value, in analytical chemistry, measure of the degree of unsaturation of an oil, fat, or wax; the amount of iodine, in grams, that is taken up by 100 grams of the oil, fat, or wax. Saturated oils, fats, and waxes take up no iodine; therefore their iodine value is zero; but unsaturated o

  • iodine-127 (chemical isotope)

    iodine: Occurrence and distribution: …isotope of iodine is stable iodine-127. An exceptionally useful radioactive isotope is iodine-131, which has a half-life of eight days. It is employed in medicine to monitor thyroid gland functioning, to treat goitre and thyroid cancer, and to locate tumours of the brain and of the liver. It is also…

  • iodine-131 (chemical isotope)

    iodine: Occurrence and distribution: …exceptionally useful radioactive isotope is iodine-131, which has a half-life of eight days. It is employed in medicine to monitor thyroid gland functioning, to treat goitre and thyroid cancer, and to locate tumours of the brain and of the liver. It is also used in investigations to trace the course…

  • iodized salt (food)

    Iodized salt, table salt with small amounts of iodine added, usually as potassium iodide, to ensure against dietary deficiency of iodine. Where iodized salt is used, particularly in Switzerland and the United States, endemic goitre has disappeared. In the United States, iodized salt contains 1 part

  • iodoform (chemical compound)

    Iodoform, a yellow, crystalline solid belonging to the family of organic halogen compounds, used as an antiseptic component of medications for minor skin diseases. First prepared in 1822, iodoform is manufactured by electrolysis of aqueous solutions containing acetone, inorganic iodides, and sodium

  • iodopsin (pigment)

    visual pigment: The retinal1 forms are called iodopsins; the retinal2 forms cyanopsins.

  • iodoquinol (drug)

    antiprotozoal drug: Iodoquinol inhibits several enzymes of protozoans. It is given orally for treating asymptomatic amoebiasis and is given either by itself or in combination with metronidazole for intestinal and hepatic amoebiasis.

  • Ioele, Francesco (American gangster)

    Frankie Yale, Italian-born American gangster and national president, during its heyday (1918–28), of the Unione Siciliane, a Sicilian fraternal organization that by World War I had become a crime cartel operating in several U.S. cities and active in robbery, prostitution, labour-union extortion,

  • IOF (international organization)

    Organisation Internationale de la Francophonie (OIF), international organization founded in 1970 as the Agence de Coopération Culturelle et Technique (ACCT; Agency of Cultural and Technical Cooperation), representing French-speaking countries. The OIF was created so as to facilitate cooperation

  • Iofan, Boris Mikhaylovich (Soviet architect)

    Western architecture: Europe: …government adopted Classical monuments—such as Boris Mikhaylovich Iofan’s winning design for the Palace of the Soviets (1931), which was intended to pile Classical colonnades to a height of 1,365 feet (416 metres) and have a colossal statue of Lenin at its summit. With its gigantic Corinthian columns, the building for…

  • Ioffe, Abram Moiseyevich (Russian philosopher)

    Abram Moiseyevich Deborin, Russian Marxist philosopher who advocated Hegelian dialectics. Born into a petit bourgeois family, he joined the Leninist Bolshevik movement (1903) before Georgy Plekhanov influenced his becoming a Menshevik (1907) at the University of Bern, from which he graduated in

  • Iogaila (king of Poland)

    W?adys?aw II Jagie??o, grand duke of Lithuania (as Jogaila, 1377–1401) and king of Poland (1386–1434), who joined two states that became the leading power of eastern Europe. He was the founder of Poland’s Jagiellon dynasty. Jogaila (Jagie??o in Polish) was one of the 12 sons of Algirdas (Olgierd),

  • Iohannis, Klaus (president of Romania)

    Romania: New constitution: …ahead of his chief challenger, Klaus Iohannis, the mayor of the Transylvanian city of Sibiu and a member of Romania’s small German Lutheran minority. The initial round of polling was plagued with irregularities, however, with instances of multiple voting observed in PSD strongholds and tens of thousands of Romanians living…

  • Iol (ancient city, Algeria)

    Iol, ancient seaport of Mauretania, located west of what is now Algiers in Algeria. Iol was originally founded as a Carthaginian trading station, but it was later renamed Caesarea and became the capital of Mauretania in 25 bc. The city was famous as a centre of Hellenistic culture, and under the

  • Iola (American journalist and social reformer)

    Ida B. Wells-Barnett, African American journalist who led an antilynching crusade in the United States in the 1890s. She later was active in promoting justice for African Americans. Ida Wells was born into slavery. She was educated at Rust University, a freedmen’s school in her native Holly

  • Iola Leroy; or, Shadows Uplifted (work by Harper)

    African American literature: The novel as social analysis: Harper’s Iola Leroy; or, Shadows Uplifted (1892) attempted to counter specious notions of slavery popularized by white writers who idealized plantation life, while offering models of socially committed middle-class African Americans who exemplify the ideals of uplift that motivated much of Harper’s writing. Griggs, a Baptist…

  • Iolani Palace (building, Honolulu, Hawaii, United States)

    Honolulu: …Honolulu’s civic centre is the Iolani Palace (completed 1882); it is now a museum but served as the legislative seat until replaced by the nearby new State Capitol (an unusual rectangular structure featuring legislative chambers shaped like volcanoes and columns shaped like royal palms). Within a two-block radius of the…

  • Iolanthe; or, The Peer and the Peri (operetta by Gilbert and Sullivan)

    Arthur Sullivan: These were Iolanthe (1882), Princess Ida (1884), The Mikado; or, The Town of Titipu (1885), Ruddigore (1887), The Yeomen of the Guard (1888), and The Gondoliers (1889). The collective works of Gilbert and Sullivan became known as the “Savoy Operas.”

  • Iolaus (Greek mythology)

    Iolaus, ancient Greek hero, the nephew, charioteer, and assistant of Heracles. He was the son of Iphicles, himself mortal half brother of Heracles by the same mother, Alcmene. Iolaus aided Heracles in his second Labour, the slaying of the Hydra and its ally the crab. He also went with Heracles to

  • iolite (mineral)

    Cordierite, blue silicate mineral that occurs as crystals or grains in igneous rocks. It typically occurs in thermally altered clay-rich sediments surrounding igneous intrusions and in schists and paragneisses. Precambrian deposits of the Laramie Range, Wyo., U.S., contain more than 500,000 tons of

  • Iolo Goch (Welsh poet)

    Celtic literature: The Middle Ages: …modern conception of nature; another, Iolo Goch, in his poem to the husbandman shows traces of English ideas, as seen in Piers Plowman. Llywelyn Goch Amheurug Hen wrote some early poems in the gogynfeirdd tradition, but his “Elegy to Lleucu Llwyd” successfully combined the Welsh elegy tradition with the imported…

  • Iommi, Tony (British musician)

    Black Sabbath: July 17, 1949, Birmingham), Tony Iommi (b. February 19, 1948, Birmingham), and Bill Ward (b. May 5, 1948, Birmingham).

  • ion (physics)

    Ion, any atom or group of atoms that bears one or more positive or negative electrical charges. Positively charged ions are called cations; negatively charged ions, anions. Ions are formed by the addition of electrons to, or the removal of electrons from, neutral atoms or molecules or other ions;

  • Ion (work by Plato)

    Plato: Early dialogues: The Ion considers professional reciters of poetry and develops the suggestion that neither such performers nor poets have any knowledge.

  • Ion (work by Euripides)

    Euripides: Ion: This tragicomedy’s sombre action is reversed by a recognition scene. In Ion (c. 413 bc), Creusa, the queen of Athens, is married to an immigrant king, Xuthus, but the couple do not have any children. Years before, the Queen was raped by the god…

  • ion acoustic wave (physics)

    plasma: Waves in plasmas: The result is called an ion acoustic wave. This is just one of the many types of waves that can exist in a plasma. The brief discussion that follows touches on the main types in order of increasing wave-oscillation frequency.

  • ion beam analysis (chemistry)

    mass spectrometry: Ion-beam analysis: The separation of ions according to their mass is accomplished with static magnetic fields, time-varying electric fields, or methods that clock the speeds of ions having the same energies—the time-of-flight method. Static electric fields cannot separate ions by their mass but…

  • ion beam machining (machine tool technology)

    machine tool: Ion beam machining (IBM): In IBM a stream of charged atoms (ions) of an inert gas, such as argon, is accelerated in a vacuum by high energies and directed toward a solid workpiece. The beam removes atoms from the workpiece by transferring energy and momentum to…

  • ion chamber

    Ionization chamber, radiation detector used for determining the intensity of a beam of radiation or for counting individual charged particles. The device may consist of a gas-filled, cylindrical container in which an electric field is maintained by impressing a voltage that keeps the wall negative

  • ion channel (biology)

    Ion channel, protein expressed by virtually all living cells that creates a pathway for charged ions from dissolved salts, including sodium, potassium, calcium, and chloride ions, to pass through the otherwise impermeant lipid cell membrane. Operation of cells in the nervous system, contraction of

  • ion chromatography (chemistry)

    dating: Technical advances: …by using the methods of ion-exchange chromatography. In this process, ions are variously adsorbed from solution onto materials with ionic charges on their surface and separated from the rest of the sample. After the dating elements have been isolated, they are loaded into a mass spectrometer and their relative isotopic…

  • ion cyclotron resonance heating (physics)

    fusion reactor: Plasma heating: This technique is called ion cyclotron resonance heating. Similarly, electron cyclotron resonance heating may be used to heat electrons. Such electron heating requires very high frequencies (tens to hundreds of gigahertz), such as produced by free-electron lasers and gyrotron tubes.

  • ion cyclotron wave (physics)

    plasma: Higher frequency waves: …(called the electron cyclotron and ion cyclotron waves, respectively) cause electron and cyclotron resonances (synchronization) at the appropriate resonance frequencies. Beyond these resonances, transverse wave propagation does not occur at all until frequencies comparable to and above the plasma frequency are reached.

  • ion drifting, lithium- (physics)

    radiation measurement: Silicon detectors: …detectors, a process known as lithium-ion drifting can be employed. This process produces a compensated material in which electron donors and acceptors are perfectly balanced and that behaves electrically much like a pure semiconductor. By fabricating n- and p-type contacts onto the opposite surface of a lithium-drifted material and applying…

  • ion engine (technology)

    aerospace industry: Propulsion: …simple electric propulsion systems, or ion engines, have been used as well. Ion engines give a positive electric charge to atoms or molecules and then accelerate the resulting ions to high speed to produce thrust. Boeing Satellite Systems (formerly part of Hughes Electronics) makes the Xenon Ion Propulsion System (XIPS)…

  • ion exchanger (chemistry)

    chromatography: Subsequent developments: Ion exchangers are natural substances—for example, certain clays—or deliberately synthesized resins containing positive ions (cation exchangers) or negative ions (anion exchangers) that exchange with those ions in solution having a greater affinity for the exchanger. This selective affinity of the solid is called ion, or…

  • ion exclusion (chemistry)

    sugar: Molasses processing: One prominent desugarization process is ion exclusion, which separates compounds by their molecular weight and electrical charge. A fraction containing salts and high-molecular-weight colorants and saccharides comes first off the resin column; then comes a sucrose fraction, and then a betaine fraction (trimethylglycine, a component of sugar beets), which may…

  • ion implantation (industrial process)

    radiation: Surface effects: Ion implantation involves the irradiation of solids by beams of energetic ions emanating from particle accelerators. Typical energies employed are on the order of 100 keV (100,000 electron volts). Typical depths of penetration are on the order of several thousand angstroms, depending on energy, ion…

  • ion microanalyzer (scientific instrument)

    mass spectrometry: Secondary-ion emission: …is the basis for the ion microprobe.

  • ion microprobe (scientific instrument)

    mass spectrometry: Secondary-ion emission: …is the basis for the ion microprobe.

  • Ion of Chios (Greek poet)

    biography: Antiquity: …century bce with the poet Ion of Chios, who wrote brief sketches of such famous contemporaries as Pericles and Sophocles. It continued throughout the classical period for a thousand years, until the dissolution of the Roman Empire in the 5th century ce. Broadly speaking, the first half of this period…

  • ion pair (chemistry and physics)

    Ion pair, in physics and chemistry, a duplex of charged particles (ordinarily charged atoms or molecules), one positive, the other negative. An ion pair, for the physicist, is the positively charged particle (positive ion) and the negatively charged particle (negative ion) simultaneously produced

  • ion product (chemical equation)

    acid–base reaction: Acid–base equilibria: …equation, Ks is termed the ion product or the autoprotolysis constant of the solvent. The concentrations are usually expressed in moles per litre, a mole being the molecular weight of the compound in grams. Since a solvent that is a good proton donor is normally a poor proton acceptor, and…

  • ion pump (biology)

    cell: Transport across the membrane: …(through the work of an ion pump, for example), the solute may be returned to its former concentration and state of high free energy. This “coupling” of work processes is, in effect, a transferal of free energy from the pump to the solute, which is then able to repeat the…

  • ion saturation

    radiation measurement: Ion chambers: …marks the onset of the ion-saturation region, where the current no longer depends on applied voltage; this is the region of operation normally chosen for ion chambers. Under these conditions the current measured in the external circuit is simply equal to the rate of formation of charges in the gas…

  • ion scattering spectroscopy (physics)

    surface analysis: Secondary ion mass spectroscopy and ion scattering spectroscopy: For both SIMS and ISS, a primary ion beam with kinetic energy of 0.3–10 keV, usually composed of ions of an inert gas, is directed onto a surface. When an ion strikes the surface, two events can occur. In one scenario the…

  • ion source (scientific device)

    mass spectrometry: Ion sources: Historically this was the first way of producing a beam of ions and came quite naturally out of the 19th-century experiments for observing the passage of electricity in gases at low pressure. Two planar electrodes oriented perpendicular to the axis of…

  • ion tail (astronomy)

    comet: General considerations: The ion tail forms from the volatile gases in the coma when they are ionized by ultraviolet photons from the Sun and blown away by the solar wind. Ion tails point almost exactly away from the Sun and glow bluish in colour because of the presence…

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