Ulster Volunteer Force (UVF), Protestant paramilitary organization founded in Northern Ireland in 1966. Its name was taken from a Protestant force organized in 1912 to fight against Irish Home Rule. Augustus (Gusty) Spence was the group’s best-known leader. The UVF was affiliated with the

Ireland: The 20th-century crisis: …established a paramilitary army, the Ulster Volunteer Force (UVF), to coordinate armed resistance. In September 1913 Carson announced that a provisional government of Ulster would be established in the event of Home Rule’s coming into effect. After at first seeking to reject Home Rule for all of Ireland, the unionists…

Edmund Mortimer, 5th earl of March was a friend of the Lancastrian king Henry V and an unwilling royal claimant advanced by rebel barons. Edmund was the great-grandson of Lionel, duke of Clarence, the second surviving son of Edward III, and was considered by some to be the heir presumptive of the

Hugh de Lacy, earl of Ulster was one of the most powerful Anglo-Norman lords in Ulster (in Ireland) in the first half of the 13th century. He was the younger son of Hugh de Lacy, 1st lord of Meath. For a time he was coadjutor of John de Courci in Leinster and Munster, but after 1200 the rivalry

Lionel of Antwerp, duke of Clarence was the second surviving son of King Edward III of England and ancestor of Edward IV. Before he was four years of age Lionel was betrothed to Elizabeth (d. 1363), daughter and heiress of William de Burgh, earl of Ulster (d. 1333), and he entered nominally into

Richard de Burgh, 2nd earl of Ulster was one of the most powerful Irish nobles of the late 13th and early 14th centuries. He was a member of a historic Anglo-Irish family, the Burghs, and son of Walter de Burgh (c. 1230–71), the 1st earl of Ulster (of the second creation). In 1286 he ravaged

Northern Ireland: Education: The University of Ulster was established in 1984 by the merger of the New University of Ulster (at Coleraine) and the Ulster Polytechnic. It has campuses at Coleraine, Jordanstown, Derry, and Belfast.

Richard de Burgh, 2nd earl of Ulster: 1230–71), the 1st earl of Ulster (of the second creation).

Omagh: The Ulster American Folk Park north of Omagh is an outdoor display site depicting tools, buildings, and conveyances used by Ulster’s 18th- and 19th-century Roman Catholic and Protestant emigrants to the United States.

major industrial polymers: Polyimides: …Torlon by Amoco Corporation) and polyetherimide (PEI; trademark Ultem); these two compounds combine the imide function with amide and ether groups, respectively.

Richard Garriott: The Ultima series that followed established him as a major player in the computer-gaming industry, and in 1983 Garriott cofounded Origin Systems, Inc. Garriott’s in-game avatar, Lord British, ruled the kingdom of Britannia, and players engaged in quests to defeat a series of evils. With the…

Richard Garriott: With the debut of Ultima IV: Quest of the Avatar (1985), players were faced with ethical dilemmas as well as challenges of might and magic. Nonplayer characters (NPCs) could converse more realistically, and Britannia was now a fully realized world, with shifting winds and a predictable lunar cycle. In…

María Luisa Bombal: …niebla as the basis for The House of Mist (1947), an English-language novel that she considered an entirely new work. The House of Mist details an unloving marriage between Daniel, who clings to the memory of his first wife, and Helga, who takes a mysterious blind lover who may or…

Cristina Peri Rossi: …última noche de Dostoievski (1992; Dostoevsky’s Last Night), Desastres íntimos (1997; Intimate Disasters), and El amor es una droga dura (1999; “Love Is a Strong Drug”).

Latin American literature: Post-boom writers: …noche que pasé contigo (1991; The Last Night I Spent with You) is Montero’s best-known novel. Its hilarious plot involves couples who meet during a Caribbean cruise. Chaviano’s El hombre la hembra y el hambre (1998; “Man, Woman, and Hunger”) is about a young woman in contemporary Cuba who works…

Richard Garriott: …Garriott and his team created Ultima Online, a pioneer in the burgeoning genre of online computer games. Three years later he started Destination Games, which later became part of NCsoft, the world’s largest online-game developer and publisher. In November 2007 he launched the multiplayer online computer game Tabula Rasa.

Australian literature: Nationalism and expansion: The last volume, Ultima Thule, graphically describes conditions in the goldfields and brings its character studies of the temperamentally opposite spouses Richard and Mary to a profoundly moving climax. Katharine Susannah Prichard’s realism in Working Bullocks (1926) and in Coonardoo (1929), her sympathetic portrait of an Aboriginal woman,…

New Horizons: …by another Kuiper belt object, Arrokoth, on January 1, 2019. Arrokoth was found to be a contact binary—that is, two Kuiper belt objects that had merged together.

ultima Thule, in literature, the furthest possible place in the world. Thule was the northernmost part of the habitable ancient world. (See Thule culture.) References to ultima Thule in modern literature appear in works by Edgar Allan Poe, Henry Wadsworth Longfellow, and the Australian writer Henry

coal: Chemical content and properties: …form of “proximate” and “ultimate” analyses, whose analytical conditions are prescribed by organizations such as ASTM. A typical proximate analysis includes the moisture, ash, volatile matter, and fixed carbon contents. (Fixed carbon is the material, other than ash, that does not vaporize when heated in the absence of air.…

sea level, position of the air-sea interface, to which all terrestrial elevations and submarine depths are referred. The sea level constantly changes at every locality with the changes in tides, atmospheric pressure, and wind conditions. Longer-term changes in sea level are influenced by Earth’s

biodegradability: Stages and rates of biodegradation: MineralizationMineralization, also called ultimate biodegradation or complete biodegradation, is the final stage in the biodegradation process. Having been degraded into such components as water and carbon dioxide and assimilated by living organisms, the mineral components of the original material are eventually redistributed by Earth’s various…

animal social behaviour: Proximate versus ultimate causation: …arises in animals) from its ultimate cause (that is, the evolutionary history and functional utility of the behaviour). Proximate causes include hereditary, developmental, structural, cognitive, psychological, and physiological aspects of behaviour. In other words, proximate causes are the mechanisms directly underlying the behaviour. For example, an animal separated from the…

mixed martial arts: History of MMA: The name referred to the Ultimate Fighting Championship (UFC), an organization that became the leading promoter of MMA events. The earliest aim of the UFC events was to pit fighters of different styles against each other—such as wrestler against boxer and kickboxer against judoka. Initially, the only rules decreed no…

Richard Ford: The Ultimate Good Luck (1981) presents an American in Mexico who is drawn reluctantly into violence and murder as he tries to get his girlfriend’s brother out of jail. Frank Bascombe, the protagonist of The Sportswriter (1986), is an alienated middle-aged sportswriter reflecting on his…

metallurgy: Testing mechanical properties: …the sample, is called the ultimate tensile stress (UTS). The final length minus the initial length, divided by the initial length, is called the elongation. Yield stress, UTS, and elongation are the most commonly tabulated mechanical properties of metals.

Ugo Foscolo: …lettere di Jacopo Ortis (1802; The Last Letters of Jacopo Ortis, 1970) contains a bitter denunciation of that transaction and shows the author’s disgust with Italy’s social and political situation. Some critics consider this story the first modern Italian novel.

Massimo Taparelli, marquis d’Azeglio: His chief work, Gli ultimi casi de Romagna (1846; “The Last Chances for Romagna”), is a trenchant political critique of the papal government of Romagna; it demanded that its populace renounce local revolts and show confidence in the Piedmontese king of Sardinia, Charles Albert, who would head a…

José Rizal: …Fort Santiago, Rizal wrote “Último adiós” (“Last Farewell”), a masterpiece of 19th-century Spanish verse.

Bad Bunny: …released his third solo album, El último tour del mundo (“The Last World Tour”). It became the first Spanish-language album to debut at number one on the Billboard 200 chart, and the recording won the Grammy for best música urbana album. Bad Bunny’s success continued with Un verano sin ti…

ultimobranchial gland, in biology, any of the small bodies in the pharynx that develop behind the fifth pair of gill pouches in the vertebrate embryo. In mammals the ultimobranchial tissue has become incorporated into the parafollicular cells of the thyroid gland. Ultimobranchial glands produce the

hormone: Ultimobranchial tissue and calcitonin: Its actual source is the ultimobranchial tissue, represented in vertebrates from fishes upward by the ultimobranchial gland, which develops from the hinder part of the pharynx. Ultimobranchial tissue is the source of distinctive cells (called light, C, or parafollicular cells), which are found in the thyroid gland of mammals; in…

primogeniture and ultimogeniture: ultimogeniture, preference in inheritance that is given by law, custom, or usage to the eldest son and his issue (primogeniture) or to the youngest son (ultimogeniture, or junior right). In exceptional cases, primogeniture may prescribe such preferential inheritance to the line of the eldest daughter.…

Ultisol, one of the 12 soil orders in the U.S. Soil Taxonomy. Ultisols are reddish, clay-rich, acidic soils that support a mixed forest vegetation prior to cultivation. They are naturally suitable for forestry, can be made agriculturally productive with the application of lime and fertilizers, and

ultra, the extreme right wing of the royalist movement in France during the Second Restoration (1815–30). The ultras represented the interests of the large landowners, the aristocracy, clericalists, and former émigrés. They were opposed to the egalitarian and secularizing principles of the

Ultra, Allied intelligence project that tapped the very highest level of encrypted communications of the German armed forces, as well as those of the Italian and Japanese armed forces, and thus contributed to the Allied victory in World War II. At Bletchley Park, a British government establishment

geomagnetic field: Magnetohydrodynamic waves—magnetic pulsations: …class of electromagnetic waves called ultralow-frequency (ULF) waves, with frequencies from one to 1,000 megahertz. Because the frequencies are so low, the waves are usually characterized by their period of oscillation (one to 1,000 seconds) rather than by frequency.

Frederick William Winterbotham: …general public in his book The Ultra Secret (1974).

pasteurization: Ultra-high-temperature (UHT) pasteurization involves heating milk or cream to 138–150 °C (280–302 °F) for one or two seconds. Packaged in sterile, hermetically sealed containers, UHT milk may be stored without refrigeration for months. Ultrapasteurized milk and cream are heated to at least 138 °C for…

ultra-Orthodox Judaism, any of several groups within Orthodox Judaism that strictly observe Jewish religious law and separate themselves from Gentile society as well as from Jews who do not follow the religious law as strictly as they do. Ultra-Orthodox communities are found primarily in Israel,

ultra-processed food (UPF), any of a variety of industrially produced foods that contain or are made primarily of highly processed ingredients, including artificial additives, and that typically have high levels of fat, sugar, or salt. Examples of ultra-processed foods include frozen foods,

Churrigueresque, Spanish Rococo style in architecture, historically a late Baroque return to the aesthetics of the earlier Plateresque (q.v.) style. In addition to a plethora of compressed ornament, surfaces bristle with such devices as broken pediments, undulating cornices, reversed volutes,

mineral deposit: Carbonatite deposits: …silica contents) or to the ultramafic igneous rocks (rocks with silica contents below approximately 50 percent by weight) known as kimberlites and lamproites. These associations suggest a common derivation, but details of the way that carbonatite magmas might concentrate geochemically scarce metals remain conjectural.

centrifuge: Vacuum-type centrifuges: Many vacuum-type centrifuges are ultracentrifuges; i.e., they operate at speeds of more than about 20,000 revolutions per minute. Figure 2 shows a schematic diagram of an early vacuum-type ultracentrifuge. The centrifuge rotor located inside the vacuum chamber is connected to the air-supported, air-driven turbine by a vertical, small-diameter, flexible…

H II region: Ultracompact H II region: This picture of the evolution of H II regions and molecular clouds is one of constant turmoil, a few transient O stars serving to keep the material stirred, in constant motion, continually producing new stars and churning clouds of gas and…

metalogic: Ultrafilters, ultraproducts, and ultrapowers: ) An ultrafilter on a nonempty set I is defined as a set D of subsets of I such that

dialysis: …this process is prevented by ultrafiltration, by which some of the water, along with some dissolved materials, is forced through the membrane by maintaining the blood at a higher pressure than the solution.

foundations of mathematics: Intuitionistic logic: …even more extreme position, called ultrafinitism, maintains that even very large numbers do not exist, say numbers greater than 10(1010). Of course, the vast majority of mathematicians reject this view by referring to 10(1010) + 1, but the true believers have subtle ways of getting around this objection, which, however,…

UHF, conventionally defined portion of the electromagnetic spectrum, encompassing radiations having a wavelength between 0.1 and 1 m and a frequency between 3,000 and 300 megahertz. UHF signals are used extensively in televison broadcasting. UHF waves typically carry televison signals on channels

polyethylene: Ultrahigh-molecular-weight polyethylene: Linear polyethylene can be produced in ultrahigh-molecular-weight versions, with molecular weights of 3,000,000 to 6,000,000 atomic units, as opposed to 500,000 atomic units for HDPE. These polymers can be spun into fibres and then drawn, or stretched, into a highly crystalline state, resulting…

pasteurization: Ultra-high-temperature (UHT) pasteurization involves heating milk or cream to 138–150 °C (280–302 °F) for one or two seconds. Packaged in sterile, hermetically sealed containers, UHT milk may be stored without refrigeration for months. Ultrapasteurized milk and cream are heated to at least 138 °C for…

jet engine: Medium-bypass turbofans, high-bypass turbofans, and ultrahigh-bypass engines: Moving up in the spectrum of flight speeds to the transonic regime—Mach numbers from 0.75 to 0.9—the most common engine configurations are turbofan engines, such as those shown in Figures 4 and 5. In a turbofan, only a part of the gas horsepower…

Ultraism, movement in Spanish and Spanish American poetry after World War I, characterized by a tendency to use free verse, complicated metrical innovations, and daring imagery and symbolism instead of traditional form and content. Influenced by the emphasis on form of the French Symbolists and

Ultraism, movement in Spanish and Spanish American poetry after World War I, characterized by a tendency to use free verse, complicated metrical innovations, and daring imagery and symbolism instead of traditional form and content. Influenced by the emphasis on form of the French Symbolists and

Utrecht, gemeente (municipality), central Netherlands. It lies along the Kromme Rijn (Winding, or Crooked, Rhine), Oude (Old) Rijn, and Vecht rivers and the Amsterdam–Rijn Canal. Its original Roman name, Trajectum ad Rhenum (Ford on the Rhine), later became Ultrajectum, and then Utrecht. The site

tanker: …descending order by size, are:

airplane: Heavier-than-air: Ultralights, which were originally merely hang gliders adapted for power by the installation of small engines similar to those used in chain saws, have matured into specially designed aircraft of very low weight and power but with flying qualities similar to conventional light aircraft. They…

Infrared Astronomical Satellite: …spectrum (these are known as ultraluminous infrared galaxies), apparently owing to a massive burst of star formation during the merger of two galaxies.

mineral deposit: Carbonatite deposits: …silica contents) or to the ultramafic igneous rocks (rocks with silica contents below approximately 50 percent by weight) known as kimberlites and lamproites. These associations suggest a common derivation, but details of the way that carbonatite magmas might concentrate geochemically scarce metals remain conjectural.

Council of India, supervisory body established in 1604 by Philip III of Spain, who also ruled Portugal. It oversaw Portuguese colonial affairs along the lines of the Spanish Council of the Indies. After the reestablishment of Portuguese independence from Spain in 1640, the Council of India was

marathon: Ultramarathons, which are neither Olympic nor World Athletics events, are longer races based on a specific distance or an allotted time period for competition, such as a 12-hour race.

ultramarine, pigment in the gem lapis lazuli, used by painters as early as the European Middle Ages. Ore containing the colour was ground, and the powdered lapis lazuli was separated from the other mineral matter. The pigment was first produced artificially in the late 1820s in France and Germany,

Malcolm Lowry: …University of Cambridge he wrote Ultramarine (1933; reissued 1963), a novel based on his sea voyage.

balance: The ultramicrobalance is any weighing device that serves to determine the weight of smaller samples than can be weighed with the microbalance—i.e., total amounts as small as one or a few micrograms. The principles on which ultramicrobalances have been successfully constructed include elasticity in structural elements,…

ultramicroscope, microscope arrangement used to study colloidal-size particles that are too small to be visible in an ordinary light microscope. The particles, usually suspended in a liquid, are illuminated with a strong light beam perpendicular to the optical axis of the microscope. These

Wilhelm His: In 1865 His invented the microtome, a mechanical device used to slice thin tissue sections for microscopic examination. He was the author of Anatomie menschlicher Embryonen, 3 vol. (1880–85; “Human Embryonic Anatomy”), considered the first accurate and exhaustive study of the development of the human embryo.

technology of photography: The ultraminiature or subminiature: This camera takes narrow roll film (16-mm or 9.5-mm) in special cartridges or film disks. The picture size ranges from 8 × 10 mm to 13 × 17 mm. These formats are used for making millions of snapshooting pocket-size cameras; special versions may be…

Ultramontanism, (from Medieval Latin ultramontanus, “beyond the mountains”), in Roman Catholicism, a strong emphasis on papal authority and on centralization of the church. The word identified those northern European members of the church who regularly looked southward beyond the Alps (that is, to

pasteurization: Ultrapasteurized milk and cream are heated to at least 138 °C for at least two seconds, but, because of less stringent packaging, they must be refrigerated. Shelf life is extended to 60–90 days. After opening, spoilage times for both UHT and ultrapasteurized products are similar…

metalogic: Elementary logic: …(see below Ultrafilters, ultraproducts, and ultrapowers)—in particular, the ultrapower when the structures are all copies of the same structure (just as the product of a1, . . ., an is the same as the power an, if ai = a for each i). The intuitive idea in this method is…

metalogic: Elementary logic: …special combination called the “ultraproduct” of a family of structures (see below Ultrafilters, ultraproducts, and ultrapowers)—in particular, the ultrapower when the structures are all copies of the same structure (just as the product of a1, . . ., an is the same as the power an, if ai =…

ultra, the extreme right wing of the royalist movement in France during the Second Restoration (1815–30). The ultras represented the interests of the large landowners, the aristocracy, clericalists, and former émigrés. They were opposed to the egalitarian and secularizing principles of the

ultra, the extreme right wing of the royalist movement in France during the Second Restoration (1815–30). The ultras represented the interests of the large landowners, the aristocracy, clericalists, and former émigrés. They were opposed to the egalitarian and secularizing principles of the

ultrasonics: Chemical and electrical uses: The ultrasonic delay line is a thin layer of piezoelectric material used to produce a short, precise delay in an electrical signal. The electrical signal creates a mechanical vibration in the piezoelectric crystal that passes through the crystal and is converted back to an electrical signal.…

ultrasonics: Therapy and surgery: …cases, a device called an ultrasonic lithotripter focuses the ultrasound with the help of X-ray guidance, but a more common technique for destruction of kidney stones, known as endoscopic ultrasonic disintegration, uses a small metal rod inserted through the skin to deliver ultrasound in the 22- to 30-kilohertz frequency region.

acoustic microscope, instrument that uses sound waves to produce an enlarged image of a small object. In the early 1940s Soviet physicist Sergey Y. Sokolov proposed the use of ultrasound in a microscope and showed that sound waves with a frequency of 3,000 megahertz (MHz) would have a resolution

ultrasonics: Diagnosis: Ultrasonic scanning in medical diagnosis uses the same principle as sonar. Pulses of high-frequency ultrasound, generally above one megahertz, are created by a piezoelectric transducer and directed into the body. As the ultrasound traverses various internal organs, it encounters changes in acoustic impedance, which cause…

ultrasonics: Transducers: An ultrasonic transducer is a device used to convert some other type of energy into an ultrasonic vibration. There are several basic types, classified by the energy source and by the medium into which the waves are being generated. Mechanical devices include gas-driven, or pneumatic, transducers…

ultrasonics, vibrations of frequencies greater than the upper limit of the audible range for humans—that is, greater than about 20 kilohertz. The term sonic is applied to ultrasound waves of very high amplitudes. Hypersound, sometimes called praetersound or microsound, is sound waves of frequencies

welding: Ultrasonic welding: Ultrasonic joining is achieved by clamping the two pieces to be welded between an anvil and a vibrating probe or sonotrode. The vibration raises the temperature at the interface and produces the weld. The main variables are the clamping force, power input, and…

ultrasonics, vibrations of frequencies greater than the upper limit of the audible range for humans—that is, greater than about 20 kilohertz. The term sonic is applied to ultrasound waves of very high amplitudes. Hypersound, sometimes called praetersound or microsound, is sound waves of frequencies

ultrasound, in medicine, the use of high-frequency sound (ultrasonic) waves to produce images of structures within the human body. Ultrasonic waves are sound waves that are above the range of sound audible to humans. The ultrasonic waves are produced by the electrical stimulation of a piezoelectric

ultrasonics, vibrations of frequencies greater than the upper limit of the audible range for humans—that is, greater than about 20 kilohertz. The term sonic is applied to ultrasound waves of very high amplitudes. Hypersound, sometimes called praetersound or microsound, is sound waves of frequencies

ultrasound, in medicine, the use of high-frequency sound (ultrasonic) waves to produce images of structures within the human body. Ultrasonic waves are sound waves that are above the range of sound audible to humans. The ultrasonic waves are produced by the electrical stimulation of a piezoelectric

diathermy: …in hospitals and clinics: shortwave, ultrasound, and microwave. In shortwave diathermy, the part to be treated is placed between two condenser plates, and the highest temperature is concentrated in the subcutaneous tissues. Shortwave usually is prescribed as treatment for deep muscles and joints and is sometimes used to localize deep…

human nutrition: Minerals: The term ultratrace elements is sometimes used to describe minerals that are found in the diet in extremely small quantities (micrograms each day) and are present in human tissue as well; these include arsenic, boron, nickel, silicon, and vanadium. Despite demonstrated roles in experimental animals, the exact…

radiation: Linear energy transfer and track structure: …this outer region, or “ultratrack,” is due primarily to electronic excitation and ionization by secondary electrons having sufficient energy to escape from the infratrack. In contrast to the infratrack, the ultratrack does not have well-defined physical bounds. Its spatial extent may reasonably be equated with the maximum range of…

ultraviolet astronomy, study of the ultraviolet spectra of astronomical objects. Ultraviolet radiation comes from a hotter region of the electromagnetic spectrum than visible light. For example, interstellar gas at temperatures close to 1,000,000 kelvins is quite prominent in the ultraviolet. It

radiation: Surface effects: Ultraviolet curing is a process in which polymers, generally employed as coatings, are irradiated by ultraviolet light. Such action produces electronic excitation and ionization of the long chain molecules that make up the polymer, either directly or through the mediation of imbedded, light-sensitive “activators.” This…

ultraviolet lamp, device for producing electromagnetic radiations in the wavelengths between those of visible light and X-rays. The Sun’s rays are rich in such radiation, sometimes referred to as black light because it is not visible to the unaided eye. The ultraviolet lamp usually consists of an

ultraviolet radiation, that portion of the electromagnetic spectrum extending from the violet, or short-wavelength, end of the visible light range to the X-ray region. Ultraviolet (UV) radiation is undetectable by the human eye, although, when it falls on certain materials, it may cause them to

microscope: Ultraviolet microscopes: Ultraviolet (UV) microscopy was developed in the early 20th century by the German scientists August Köhler and Moritz von Rohr. Because of the shorter wavelength of UV light, higher resolution was possible, but the opacity of conventional glass lenses to these wavelengths necessitated…

spectroscopy: Photoelectron spectroscopy: Photoelectron spectroscopy is an extension of the photoelectric effect (see radiation: The photoelectric effect), first explained by Einstein in 1905, to atoms and molecules in all energy states. The technique involves the bombardment of a sample

coloration: The selective agent: …the human eye; when an ultraviolet camera is used to photograph such flowers, however, various bright patterns and nectar guides are revealed that appear to be highly species specific (see photograph). The importance of strong contrast and contour in the attraction of insects to flowers is related to the perceptual…

ultraviolet radiation, that portion of the electromagnetic spectrum extending from the violet, or short-wavelength, end of the visible light range to the X-ray region. Ultraviolet (UV) radiation is undetectable by the human eye, although, when it falls on certain materials, it may cause them to

ultraviolet radiation: Unlike X-rays, ultraviolet radiation has a low power of penetration; hence, its direct effects on the human body are limited to the surface skin. The direct effects include reddening of the skin (sunburn), pigmentation development (suntan), aging, and carcinogenic changes. Ultraviolet sunburns can be mild, causing only…

spectroscopy: Visible and ultraviolet spectroscopy: Colours as perceived by the sense of vision are simply a human observation of the inverse of a visible absorption spectrum. The underlying phenomenon is that of an electron being raised from a low-energy

ultraviolet telescope, telescope used to examine the ultraviolet portion of the electromagnetic spectrum, between the portion seen as visible light and the portion occupied by X-rays. Ultraviolet radiation has wavelengths of about 400 nanometres (nm) on the visible-light side and about 10 nm on the

ultraviolet radiation, that portion of the electromagnetic spectrum extending from the violet, or short-wavelength, end of the visible light range to the X-ray region. Ultraviolet (UV) radiation is undetectable by the human eye, although, when it falls on certain materials, it may cause them to

chemical analysis: Ultraviolet-visible spectrophotometry: Absorption in the ultraviolet-visible region of the spectrum causes electrons in the outermost occupied orbital of an atom or molecule to be moved to a higher (i.e., farther from the nucleus) unoccupied orbital. Ultraviolet-visible absorptiometry is principally used for quantitative analysis of atoms…