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  • Proto-Karenic language

    Sino-Tibetan languages: Proto-Tibeto-Burman: The sound system of Proto-Karenic appears closely related to that of Proto-Tibeto-Burman. The tonal classes can be reduced to two, which connect Karen to Burmic, Sinitic, Tai, and Hmong-Mien.

  • Proto-Kartvelian language

    Caucasian languages: Proto-Kartvelian: A comparative study of the Kartvelian languages enables specialists to outline the general structure of the parent language, called Proto-Kartvelian, which yielded the known Kartvelian, or South Caucasian, languages. One of the most characteristic features of the Proto-Kartvelian language is the functional vowel alternation,…

  • Proto-Malayo-Polynesian language

    Austronesian languages: Phonology: …this system to that of Proto-Malayo-Polynesian (the hypothetical ancestor of all non-Formosan Austronesian languages) are the merger of *C and *t as PMP *t, the merger of *N and *n as PMP *n, and the shift of *S to PMP *h (and of *eS to *ah). A number of other…

  • Proto-Melanesian language

    Austronesian languages: Major subgroups: …which is known today as Proto-Oceanic. The Oceanic hypothesis maintains that all Austronesian languages east of a line that runs through Indonesian New Guinea at approximately 138° E longitude—except for Palauan and Chamorro of western Micronesia—are descended from a single protolanguage spoken many generations after the initial breakup of Proto-Austronesian…

  • Proto-Mongol (people)

    Manchuria: Manchuria to about 1900: …Tungus, and the Mongols and Proto-Mongols. The Tungus (from which several groups emerged) were forest and plain dwellers who had a mixed economy of agriculture, fishing, hunting, and livestock breeding. Those in Manchuria were known in various historical periods by such names as Sushen, Yilou, Fuyu, Mohe, Juchen (Nüzhen), and,…

  • proto-Moon (astronomy)

    Moon: Origin and evolution: …eject the right kind of proto-Moon. According to capture theories, the Moon formed elsewhere in the solar system and was later trapped by the strong gravitational field of Earth. This scenario remained popular for a long time, even though the circumstances needed in celestial mechanics to brake a passing Moon…

  • Proto-Oceanic language

    Austronesian languages: Major subgroups: …which is known today as Proto-Oceanic. The Oceanic hypothesis maintains that all Austronesian languages east of a line that runs through Indonesian New Guinea at approximately 138° E longitude—except for Palauan and Chamorro of western Micronesia—are descended from a single protolanguage spoken many generations after the initial breakup of Proto-Austronesian…

  • proto-oncogene

    oncogene: …from its original form, the proto-oncogene. Operating as a positive growth regulator, the proto-oncogene is involved in promoting the differentiation and proliferation of normal cells. A variety of proto-oncogenes are involved in different crucial steps of cell growth, and a change in the proto-oncogene’s sequence or in the amount of…

  • Proto-Romance (language)

    Vulgar Latin: …sometimes also used for so-called Proto-Romance (roman commun), a theoretical construct based on consistent similarities among all or most Romance languages. All three senses of the term Vulgar Latin in fact share common features but, given their different theoretical status, can hardly be called identical or even comparable. When Christianity…

  • Proto-Scandinavian language (language)

    Scandinavian languages: History of Old Scandinavian: It is known as Proto-Scandinavian, or Ancient Scandinavian, but shows few distinctively North Germanic features. The earliest inscriptions may reflect a stage, sometimes called Northwest Germanic, prior to the splitting of North and West Germanic (but after the separation of Gothic). Only after the departure of the Angles and…

  • Proto-Semitic language

    Afro-Asiatic languages: Proving genetic relationship: problems of internal comparison: , Proto-Chadic or Proto-Semitic), or a hypothetical common sound of origin. Languages are said to be genetically related when they meet two criteria: they match in phonology, vocabulary, and grammar in such a way that they can be systematically related to a common protolanguage, and the matches can…

  • Proto-Sinaitic inscriptions (ancient writing)

    Sinaitic inscriptions, archeological remains that are among the earliest examples of alphabetic writing; they were inscribed on stones in the Sinai Peninsula, where they were first discovered in 1904–05 by the British archaeologist Sir William Flinders Petrie. Apparently influenced both by E

  • Proto-Sinitic languages

    Chinese languages: …of the Chinese languages into Proto-Sinitic (Proto-Chinese; until 500 bc), Archaic (Old) Chinese (8th to 3rd century bc), Ancient (Middle) Chinese (through ad 907), and Modern Chinese (from c. the 10th century to modern times). The Proto-Sinitic period is the period of the most ancient inscriptions and poetry; most loanwords…

  • Proto-Sino-Tibetan language

    Sino-Tibetan languages: Interrelationship of the language groups: The position of Proto-Sino-Tibetan can be defined in terms of a chain of interrelated languages and language groups: Sinitic is connected with Tibetic through a body of shared vocabulary and typological features, similarly Tibetic with Baric, Baric with Burmic, and Burmic with Karenic. The chain continues at both…

  • Proto-Slavic language

    Slavic languages: Proto-Balto-Slavic: Each branch of Slavic originally developed from Proto-Slavic, the ancestral parent language of the group, which in turn developed from an earlier language that was also the antecedent of the Proto-Baltic language. Both Slavic and Baltic share with the eastern Indo-European languages (called…

  • proto-Slovene (people)

    Slovenia: The Alpine Slavs: During the 6th century ce, ancestors of the Slovenes, now referred to by historians as Alpine Slavs or proto-Slovenes, pushed up the Sava, Drava, and Mura river valleys into the Eastern Alps and the Karst. There they absorbed the existing Romano-Celtic-Illyrian cultures. At…

  • Proto-Tibeto-Burman language

    Sino-Tibetan languages: Proto-Tibeto-Burman: The Proto-Tibeto-Burman language was monosyllabic. Some grammatical units may have had the form of minor syllables before the major syllable (*ma-, *ba-) or after the major syllable (*-ma, *-ba). (An asterisk [*] indicates that the form it precedes is unattested and has been reconstructed as a…

  • Proto-Uralic language

    Uralic languages: Establishment of the family: The original homeland of Proto-Uralic is considered to have been in the vicinity of the north-central Urals, possibly centred west of the mountains. Following the dissolution of Uralic, the precursors of the Samoyeds gradually moved northward and eastward into Siberia. The Finno-Ugrians moved to the south and west, to…

  • Proto-Villanovan culture (anthropology)

    ancient Italic people: Origins: …Bronze,” and, most frequently, “Proto-Villanovan,” the social and economic changes are clear. There was an increase in population and in overall wealth, a tendency to have larger, permanent settlements, an expansion of metallurgical knowledge, and a strengthening of agricultural technology. Diagnostic archaeological criteria include the use of cremation (with…

  • Proto-Yeniseian language

    Ket language: Proto-Yeniseian, the language from which the Yeniseian languages descended, seems to have lacked nasals in the initial position. The lack of proven relatives and the absence of reliable written sources earlier than the middle of the 19th century make it uncertain whether the tone, or…

  • protoactinium (isotope)

    protactinium: The long-lived isotope protactinium-231 (originally called protoactinium for “before actinium” and later shortened to protactinium) was discovered (1917) independently by German chemist Otto Hahn and Austrian physicist Lise Meitner in pitchblende, by Fajans, and by British chemists Frederick Soddy, John Cranston, and Sir Alexander Fleck. This isotope

  • Protoarticulatae (fossil plant order)

    Equisetopsida: Annotated classification: †Order Hyeniales (Protoarticulatae) Extinct shrublike plants, with short, forked leaves in whorls; 1 family: Hyeniaceae (now placed with the Polypodiopsida—true ferns—by some paleobotanists). †Order Pseudoborniales One family, Pseudoborniaceae, with a single extinct species,

  • protobranch (bivalve subclass)

    bivalve: Internal features: …the earliest mollusks—hence the name protobranch, or “first gills.” The paired gills, separated by a central axis, are suspended from the mantle roof. Individual short gill filaments extend outward from either side of the axis, and cilia on their surfaces create an upward respiratory water current that passes from the…

  • Protobranchia (bivalve subclass)

    bivalve: Internal features: …the earliest mollusks—hence the name protobranch, or “first gills.” The paired gills, separated by a central axis, are suspended from the mantle roof. Individual short gill filaments extend outward from either side of the axis, and cilia on their surfaces create an upward respiratory water current that passes from the…

  • Protoceratops (dinosaur genus)

    Protoceratops, (genus Protoceratops), ceratopsian dinosaur found as fossils in the Gobi Desert from 80-million-year-old deposits of the Late Cretaceous Period. Protoceratops was a predecessor of the more familiar horned dinosaurs such as Triceratops. Like other ceratopsians, it had a rostral bone

  • Protoceratopsidae (dinosaur family)

    ceratopsian: Members of the Protoceratopsidae, including Protoceratops and Leptoceratops, were mostly quadrupedal and slightly larger and lived from the Early to Late Cretaceous; these dinosaurs had a somewhat larger frill but no horns.

  • protocerebrum (animal anatomy)

    nervous system: Arthropods: …of three main regions: the protocerebrum, deutocerebrum, and tritocerebrum. The anterior protocerebrum, which receives the nerves of the eyes and other organs, contains centres, or neuropils, such as the optic centres and bodies known as corpora pedunculata. The neuropils function as integrative systems for the anterior sense organs, especially the…

  • Protocetidae (fossil mammal family)

    cetacean: Annotated taxonomy: †Family Protocetidae 9 genera. Early to Middle Eocene. Europe, Africa, and possibly North America. †Family Dorudontidae 5 genera. Middle to Upper Eocene. Europe, Africa, and North America. †Family Basilosauridae 1 genus. Middle to Upper Eocene. Europe, Africa, and North America.

  • protochordate (invertebrate)

    Protochordate, any member of either of two invertebrate subphyla of the phylum Chordata: the Tunicata (sea squirts, salps, etc.) and the Cephalochordata (amphioxus). Like the remaining subphylum of the chordates, the Vertebrata, the protochordates have a hollow dorsal nerve cord, gill slits, and a

  • Protociliata (protozoan)

    Opalinid, (subphylum Opalinata), any of about 150 protozoans found in the intestinal tracts of amphibians and some other animals. The nuclei of opalinids vary in number from two (e.g., Zelleriella) to many (e.g., Cepedea); the locomotor organelles (short, hairlike projections) are arranged in

  • protocloud (cosmology)

    Protogalaxy, in cosmology, vast cloud of gas that by contraction and condensation becomes a galaxy of stars. In evolutionary (“big-bang”) models of creation, protogalaxies appear early in the expansion phase of the universe; in the steady-state model they are slowly but continually forming from

  • Protococcus (genus of green algae)

    Pleurococcus, genus of green algae (family Chaetophoraceae). Pleurococcus species sometimes form a thin green covering on the moist shaded side of trees, rocks, and soil. The spherical cells, either solitary or clumped together, have heavy cell walls that protect them against excessive water loss.

  • protocol (diplomacy)

    diplomacy: Diplomatic agreements: A protocol prolongs, amends, supplements, or supersedes an existing instrument. It may contain details pertaining to the application of an agreement, an optional arrangement extending an obligatory convention, or a technical instrument as an annex to a general agreement. It may substitute for an agreement or…

  • protocol (computer science)

    Protocol, in computer science, a set of rules or procedures for transmitting data between electronic devices, such as computers. In order for computers to exchange information, there must be a preexisting agreement as to how the information will be structured and how each side will send and receive

  • Protocol for the Pacific Settlement of International Disputes (1924)

    Geneva Protocol, (1924) League of Nations draft treaty to ensure collective security in Europe. Submitted by Edvard Beneš, the protocol proposed sanctions against an aggressor nation and provided a mechanism for the peaceful settlement of disputes. States would agree to submit all disputes to the

  • Protocol for the Prohibition of the Use in War of Asphyxiating, Poisonous or Other Gases, and of Bacteriological Methods of Warfare (1925)

    Geneva Gas Protocol, in international law, treaty signed in 1925 by most of the world’s countries banning the use of chemical and biological weapons in warfare. It was drafted at the 1925 Geneva Conference as part of a series of measures designed to avoid repetition of the atrocities committed by

  • Protocol I (international law [1977])

    Geneva Conventions: The first, Protocol I, extended protection under the Geneva and Hague conventions to persons involved in wars of “self-determination,” which were redefined as international conflicts. The protocol also enabled the establishment of fact-finding commissions in cases of alleged breaches of the convention. The second protocol, Protocol II,…

  • Protocol II (international law [1977])

    Geneva Conventions: The second protocol, Protocol II, extended human rights protections to persons involved in severe civil conflicts, which had not been covered by the 1949 accords. It specifically prohibited collective punishment, torture, the taking of hostages, acts of terrorism, slavery, and “outrages on the personal dignity, in particular humiliating…

  • Protocol on Environmental Protection (Antarctic Treaty)

    Antarctica: The Madrid Protocol: …Madrid in October 1991, the Protocol on Environmental Protection to the Antarctic Treaty (also known as the Madrid Protocol). It entered into force in 1998 and designated Antarctica “as a natural reserve, devoted to peace and science.”

  • Protocol on Environmental Protection to the Antarctic Treaty (treaty [1991])

    Antarctica: The Madrid Protocol: …Madrid in October 1991, the Protocol on Environmental Protection to the Antarctic Treaty (also known as the Madrid Protocol). It entered into force in 1998 and designated Antarctica “as a natural reserve, devoted to peace and science.”

  • protocol sentence (philosophy)

    Protocol sentence, in the philosophy of Logical Positivism, a statement that describes immediate experience or perception and as such is held to be the ultimate ground for knowledge. Such a statement is also called an atomic statement, observation statement, judgment of perception, or basic

  • Protocol to Prevent, Suppress, and Punish Trafficking in Persons, Especially Women and Children (United Nations)

    human trafficking: Legal response: …2000 the UN established the Protocol to Prevent, Suppress, and Punish Trafficking in Persons, Especially Women and Children, which provided a commonly accepted working definition of human trafficking and called upon countries to promulgate laws to combat the practice, to assist victims, and to promote coordination and cooperation between countries.

  • Protocols of the Elders of Zion (fraudulent document)

    Protocols of the Elders of Zion, fraudulent document that served as a pretext and rationale for anti-Semitism mainly in the early 20th century. The document purported to be a report of a series of 24 (in other versions, 27) meetings held at Basel, Switzerland, in 1897, at the time of the first

  • Protocols of the Learned Elders of Zion (fraudulent document)

    Protocols of the Elders of Zion, fraudulent document that served as a pretext and rationale for anti-Semitism mainly in the early 20th century. The document purported to be a report of a series of 24 (in other versions, 27) meetings held at Basel, Switzerland, in 1897, at the time of the first

  • protocontinent (geology)

    Silurian Period: Laurentia: …northeastern Russia belonged to the paleocontinent Laurentia (a name derived from Quebec’s portion of the Canadian Shield). With respect to the present-day Great Lakes and Hudson Bay, Laurentia was rotated clockwise during Wenlock time to fit fully between the latitudes 30° N and 30° S of the paleoequator. The present…

  • protocooperation (biology)

    Warder Clyde Allee: …animals; he named this phenomenon protocooperation and believed it to be the basis for the conscious and unconscious cooperation among the higher animals in their levels of community organization.

  • Protoctista (eukaryote)

    Protist, any member of a group of diverse eukaryotic, predominantly unicellular microscopic organisms. They may share certain morphological and physiological characteristics with animals or plants or both. The term protist typically is used in reference to a eukaryote that is not a true animal,

  • Protocucujidae (insect family)

    coleopteran: Annotated classification: Family Protocucujidae 2 species; Chile and Australia; similar to Sphindidae. Family Silvanidae (flat grain beetles) Closely related to Cucujidae; some feed on grain (Oryzaephilus); another genus, Silvanus. Family Smicripidae

  • protoderm (plant tissue)

    angiosperm: Vegetative structures: …the plant body: the outermost protoderm differentiates into the epidermis, a tissue that protects the plant; the adjacent ground meristem differentiates into the central ground tissues (the pith and cortex); and the procambium differentiates into the vascular tissues (the xylem, phloem, and vascular cambium). The xylem and phloem are conducting…

  • protodolomite (mineral)

    dolomite: Crystal structure: The term protodolomite is frequently applied to Holocene dolomites (those formed during approximately the last 11,700 years) that have less than ideal dolomite structures. Most dolomites of ancient dolostones, however, appear to be well ordered. Modifications that may reflect diverse calcium-versus-magnesium layering aberrations are treated extensively in…

  • Protodonata (fossil insect)

    insect: Insect phylogeny: …as the giant dragonflies or Protodonata (some of which had a wing span of more than half a metre) and the dragonflies and damselflies (Odonata) and mayflies (Ephemeroptera), both of which have persisted with little change to the present. The primitive insect stock also gave rise to a neopterous stock,…

  • Protodrilida (polychaete order)

    annelid: Annotated classification: Dinophilida, Polygordiida, Protodrilida); genera include Dinophilus and Polygordius. Order Myzostomida Body disk-shaped or oval without external segmentation; external or internal commensals or parasites of echinoderms, especially crinoids; size, minute to 1 cm; genera include Myzostoma.

  • protoenstatite (mineral)

    Protoenstatite, a variety of the silicate mineral enstatite (q.v.). Protoenstatite is stable only at high

  • protofeather (zoology)

    Dilong: …fossil specimens includes impressions of protofeathers. This is the first evidence that, like many other coelurosaurs (that is, theropod dinosaurs closely related to birds), tyrannosaurs were feathered. The protofeathers were made up of branched filaments that extended to 2 cm (0.8 inch) long, but these filaments would have resembled a…

  • protogalaxy (cosmology)

    Protogalaxy, in cosmology, vast cloud of gas that by contraction and condensation becomes a galaxy of stars. In evolutionary (“big-bang”) models of creation, protogalaxies appear early in the expansion phase of the universe; in the steady-state model they are slowly but continually forming from

  • Protogenes (Greek artist)

    Protogenes, Greek painter, contemporary and rival of Apelles, noted for the care and time he devoted to each of his paintings. He lived most of his life at Rhodes. Little else is known of him, and none of his paintings survives. The “Ialysus” and the “Resting Satyr” were among the most renowned of

  • protogenesis (geological process)

    loess: Origin and age.: In protogenesis the accumulated mineral matter already has all the main loess properties because transport occurred subsequent to weathering and soil formation.

  • protogyny (hermaphroditism)

    reproductive behaviour: Fishes: …in bony fishes is the protogynous type, in which the individual functions first as a female and later as a male; it is much more frequent than the reverse situation (protandrous hermaphroditism). The selective reasons for the predominance of the former are presumably associated with the relationship between smaller body…

  • protogyny (botany)

    pollination: Structural: Protogyny, the situation in which the pistils mature first, occurs in arum lilies and many wind-pollinated plants, such as grasses—although several grasses are self-pollinated, including common varieties of wheat, barley, and oats. Avocado has both protogynous and protandrous varieties, and these often are grown together…

  • Protohomoptera (fossil insect)

    homopteran: Evolution and paleontology: …it is probable that the Protohomoptera had three tarsal segments, three ocelli, two pairs of wings about equal in size and shape with complete venation, an alimentary tract lacking a filter chamber, and male genitalia fitted with harpogones and subgenital plates.

  • protoindustrialization (European history)

    history of Europe: Protoindustrialization: Historians favour the term “protoindustrialization” to describe the form of industrial organization that emerged in the 16th century. The word was initially applied to cottage industries in the countryside. In spite of the opposition of urban guilds, rural residents were performing many industrial tasks.…

  • Protokollsatz (philosophy)

    Protocol sentence, in the philosophy of Logical Positivism, a statement that describes immediate experience or perception and as such is held to be the ultimate ground for knowledge. Such a statement is also called an atomic statement, observation statement, judgment of perception, or basic

  • protolanguage (linguistics)

    linguistics: Development of the comparative method: …were able to reconstruct “ancestral” common forms from which the later forms found in particular languages could be derived. By convention, such reconstructed forms are marked in the literature with an asterisk. Thus, from the reconstructed Proto-Indo-European word for “ten,” *dekm, it was possible to derive Sanskrit daśa, Greek déka,…

  • Protolepidodendrales (fossil plant order)

    lycophyte: Annotated classification: †Order Protolepidodendrales Extinct herbaceous (rarely woody), homosporous lycophytes; about 8 genera, including Baragwanathia and Protolepidodendron. †Order Lepidodendrales Extinct tree lycophytes, therefore capable of secondary growth; heterosporous, with some strobili (cones)

  • Protolepidodendron (fossil plant genus)

    lycophyte: Annotated classification: …8 genera, including Baragwanathia and Protolepidodendron. †Order Lepidodendrales Extinct tree lycophytes, therefore capable of secondary growth; heterosporous, with some strobili (cones) forming seedlike structures; about 6 genera, including Lepidodendron and Sigillaria. Order

  • Protoliterate Period (Mesopotamian history)

    Mesopotamian art and architecture: Architecture: …architectural design during this so-called Protoliterate period (c. 3400–c. 2900 bce) are recognizable in the construction of religious buildings. There is, however, one temple, at Abū Shahrayn (ancient Eridu), that is no more than a final rebuilding of a shrine the original foundation of which dates back to the beginning…

  • Protolophiomys ibericus (rodent)

    maned rat: …of the maned rat (Protolophiomys ibericus) was discovered in 6-million- to 7-million-year-old deposits of southern Spain. Although most of these fossils are cranial fragments, they are easily recognized as relatives of the maned rat by a granulated, bony caplike growth over the top of the entire skull—a structure unique…

  • protolysis

    organometallic compound: Carbanion character: …containing active metals is the protolysis (proton-transfer) reaction that takes place with very weak protonic acids, including water. Alcohols react in a manner similar to the reaction of water, and this provides a convenient way of introducing an alkoxide (OR) substituent into an organometallic compound. (C2H5)3Ga + HOCH3 → [(C2H5)3GaOHCH3]…

  • protolytic reaction

    organometallic compound: Carbanion character: …containing active metals is the protolysis (proton-transfer) reaction that takes place with very weak protonic acids, including water. Alcohols react in a manner similar to the reaction of water, and this provides a convenient way of introducing an alkoxide (OR) substituent into an organometallic compound. (C2H5)3Ga + HOCH3 → [(C2H5)3GaOHCH3]…

  • Protomastigida (protozoan)

    Protomonad, (order Kinetoplastida), any of an order of protozoan zooflagellates characterized as free-living or parasitic colourless organisms, typically with one or two flagella and usually without a secreted pellicle (or envelope). Solitary and colonial free-living forms usually feed by

  • Protomognathus americanus (insect)

    ant: Workers of the slave-making ant Protomognathus americanus raid nests of Temnothorax ants, stealing the latter’s pupae. The pupae are raised by P. americanus to serve as slaves, and, because the Temnothorax pupae become imprinted on the chemical odour of the slave-making ants, the captive ants forage and routinely return to…

  • protomonad (protozoan)

    Protomonad, (order Kinetoplastida), any of an order of protozoan zooflagellates characterized as free-living or parasitic colourless organisms, typically with one or two flagella and usually without a secreted pellicle (or envelope). Solitary and colonial free-living forms usually feed by

  • Protomonadida (protozoan)

    Protomonad, (order Kinetoplastida), any of an order of protozoan zooflagellates characterized as free-living or parasitic colourless organisms, typically with one or two flagella and usually without a secreted pellicle (or envelope). Solitary and colonial free-living forms usually feed by

  • proton (subatomic particle)

    Proton, stable subatomic particle that has a positive charge equal in magnitude to a unit of electron charge and a rest mass of 1.67262 × 10−27 kg, which is 1,836 times the mass of an electron. Protons, together with electrically neutral particles called neutrons, make up all atomic nuclei except

  • Proton (Russian launch vehicle)

    Proton, Russian launch vehicle used for both government and commercial payloads. Since 1965 the Proton launch vehicle has been a workhorse means of access to space, first for the Soviet Union and now Russia. Proton has been used to launch spacecraft to Venus and Mars; elements of the space stations

  • proton accelerator, linear

    linear accelerator: The proton linac, designed by the American physicist Luis Alvarez in 1946, is a more efficient variant of Wideröe’s structure. In this accelerator, electric fields are set up as standing waves within a cylindrical metal “resonant cavity,” with drift tubes suspended along the central axis. The…

  • proton acceptor (chemistry)

    chemical compound: Classification of compounds: …on the other hand, are proton acceptors. The most common base is the hydroxide ion (OH−), which reacts with an H+ ion to form a water molecule. H+ + OH− → HOH (usually written H2O)

  • proton beam (physics)

    particle accelerator: Proton synchrotrons: …built to demonstrate that the beam could be accelerated through the transition energy in a stable manner.

  • proton decoupling (physics)

    chemical compound: Carbon-13 magnetic resonance spectroscopy: …by an instrumental technique termed proton decoupling. Proton decoupling eliminates all the splitting patterns that would normally be observed in a 13C spectrum for all carbon atoms bonded to one or more hydrogen atoms and is done routinely to simplify the spectrum.

  • proton donor (chemistry)

    chemical compound: Classification of compounds: Thus, acids are defined as proton donors. The most common acids are aqueous solutions of HCl (hydrochloric acid), H2SO4 (sulfuric acid), HNO3 (nitric acid), and H3PO4 (phosphoric acid). Bases, on the other hand, are proton acceptors. The most

  • proton linac

    linear accelerator: The proton linac, designed by the American physicist Luis Alvarez in 1946, is a more efficient variant of Wideröe’s structure. In this accelerator, electric fields are set up as standing waves within a cylindrical metal “resonant cavity,” with drift tubes suspended along the central axis. The…

  • proton magnetic resonance spectroscopy

    chemical compound: Proton magnetic resonance spectroscopy: Proton NMR spectra yield a great deal of information about molecular structure because most organic molecules contain many hydrogen atoms, and the hydrogen atoms absorb energy of different wavelengths depending on their bonding environment.

  • proton microprobe (instrument)

    chemical analysis: X-ray emission: …the apparatus utilized is a proton microprobe. An electron microprobe functions in much the same manner. The scanning electron microscope utilizes electrons to bombard a surface, but the intensity of either backscattered (deflected through angles greater than 90°) or transmitted electrons is measured rather than the intensity of X rays.…

  • proton NMR

    chemical compound: Proton magnetic resonance spectroscopy: Proton NMR spectra yield a great deal of information about molecular structure because most organic molecules contain many hydrogen atoms, and the hydrogen atoms absorb energy of different wavelengths depending on their bonding environment.

  • proton nuclear magnetic resonance spectroscopy

    chemical compound: Proton magnetic resonance spectroscopy: Proton NMR spectra yield a great deal of information about molecular structure because most organic molecules contain many hydrogen atoms, and the hydrogen atoms absorb energy of different wavelengths depending on their bonding environment.

  • proton number (physics)

    Atomic number, the number of a chemical element in the periodic system, whereby the elements are arranged in order of increasing number of protons in the nucleus. Accordingly, the number of protons, which is always equal to the number of electrons in the neutral atom, is also the atomic number. An

  • proton pump inhibitor (drug)

    Proton pump inhibitor, any drug that suppresses the secretion of gastric acid by inhibiting an enzyme in the parietal cells of the stomach that exchanges acid for potassium ions. The proton pump inhibitors are used in the treatment of erosive esophagitis and peptic ulcer. When given in sufficient

  • proton radioactivity (physics)

    radioactivity: Proton radioactivity: Proton radioactivity, discovered in 1970, is exhibited by an excited isomeric state of cobalt-53, 53mCo, 1.5 percent of which emits protons:

  • proton storage ring

    particle accelerator: Proton storage rings: In 1971 CERN pioneered the storage of protons with the Intersecting Storage Rings (ISR), in which two interlaced rings each stored protons at 31 GeV. The two beams collided at eight crossing points, giving a total collision energy of 62 GeV. This…

  • proton synchrotron (device)

    particle accelerator: Proton synchrotrons: The mode of operation of a proton synchrotron is very similar to that of an electron synchrotron, but there are two important differences. First, because the speed of a proton does not approach the speed of light until its energy is well above…

  • proton theory of acids and bases (chemistry)

    Brønsted–Lowry theory, a theory, introduced independently in 1923 by the Danish chemist Johannes Nicolaus Brønsted and the English chemist Thomas Martin Lowry, stating that any compound that can transfer a proton to any other compound is an acid, and the compound that accepts the proton is a base.

  • proton-antiproton collider (device)

    Fermi National Accelerator Laboratory: …Tevatron began operation as a proton-antiproton collider—with 900-GeV protons striking 900-GeV antiprotons to provide total collision energies of 1.8 teraelectron volts (TeV; 1.8 trillion electron volts). The original main ring was replaced in 1999 by a new preaccelerator, called the Main Injector, which delivered more-intense beams to the Tevatron and…

  • proton-precession magnetometer (measurement instrument)

    geomagnetic field: Measurement of the field: One such method involves the proton-precession magnetometer, which makes use of the magnetic and gyroscopic properties of protons in a fluid such as gasoline. In this method the magnetic moments of protons are first aligned by a strong magnetic field produced by an external coil. The magnetic field is then…

  • proton-proton cycle (astronomy)

    Proton-proton cycle, chain of thermonuclear reactions that is the chief source of the energy radiated by the Sun and other cool main-sequence stars. Another sequence of thermonuclear reactions, called the carbon cycle, provides much of the energy released by hotter stars. In a proton-proton cycle,

  • proton-proton reaction (astronomy)

    Proton-proton cycle, chain of thermonuclear reactions that is the chief source of the energy radiated by the Sun and other cool main-sequence stars. Another sequence of thermonuclear reactions, called the carbon cycle, provides much of the energy released by hotter stars. In a proton-proton cycle,

  • proton-transfer reaction (chemistry)

    acid–base reaction: Proton-transfers: This represents a proton-transfer reaction from A1 to B2, producing B1 and A2. A large number of reactions in solution, often referred to under a variety of names, can be represented in this way. This is illustrated by the following examples, in each of which the species are…

  • protonema (anatomy)

    bryophyte: Form and function: The protonema, which grows directly from the germinating spore, is in most mosses an extensive, branched system of multicellular filaments that are rich in chlorophyll. This stage initiates the accumulation of hormones that influence the further growth of newly formed cells. When specific concentrations of the…

  • protonephridium (anatomy)

    nephridium: The protonephridium consists of a hollow cell located in the body cavity and a duct leading from it to an exterior opening, called a nephridiopore. Fluid in the body cavity filters into the hollow cell, called a flame bulb (or flame cell) if it possesses cilia,…

  • protonosphere (atmospheric science)

    Protonosphere, region in the Earth’s upper atmosphere where atomic hydrogen and protons (ionic hydrogen) are the dominant constituents; it can be considered the outermost extension of the ionosphere. In the lowest part of the Earth’s atmosphere, called the homosphere (100 km [about 65 miles]),

  • protopetroleum

    petroleum: From planktonic remains to kerogen: the immature stage: …the organic materials, the so-called protopetroleum, for later diagenesis (a series of processes involving biological, chemical, and physical changes) into true petroleum.

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