| radioactive pollutants | Radioactive substances which act as pollutants. They include chemicals whose radiation is released via radioactive waste, nuclear accidents, fallout from nuclear explosions, and the like. (12 Dec 1998) |
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| radioactive probe | A nucleic acid fragment, labelled by a radioisotope, biotin, etc., that is complementary to a sequence in another nucleic acid (fragment) and that will, by hydrogen binding to the latter, locate or identify it and be detected; a diagnostic technique based on the fact that every species of microbe possesses some unique nucleic acid sequences which differentiate it from all others, and thus can be used as identifying markers or "fingerprints." (05 Mar 2000) |
| radioactive thyroxine | Thyroxine in which a radioisotope of iodine (125I or 131I) is incorporated into its molecule; used in experiments tracing the metabolism of thyroxine. Synonym: labelled thyroxine, radiolabelled thyroxine, radiothyroxin. (05 Mar 2000) |
| radioactive tracer | <physics, radiobiology> A radioisotope is an element which has the same atomic number as another but a different atomic weight, exhibiting the property of spontaneous decomposition. Decomposition gives off radiation (gamma rays) that can be detected with a counter. If a radioisotope is attached to a biological compound and injected into the body, its path may be traced through the body (resulting in an image). (27 Sep 1997) |
| radioactive tracers | Radioactive substances added in minute amounts to the reacting elements or compounds in a chemical process and traced through the process by appropriate detection methods, e.g., geiger counter. Compounds containing tracers are often said to be tagged or labelled. (12 Dec 1998) |
| radioactive waste | <radiobiology> Equipment and materials from nuclear operations which are radioactive and for which there is no further anticipated use. Wastes are generally classified as high-level (having radioactivity concentrations of hundreds to thousands of curies per gallon or cubic foot), low-level (in the range of 1 microcurie per gallon or cubic foot), or intermediate (between high and low). See: curie. (09 Oct 1997) |
| gold colloid, radioactive | <chemical> A radioactive suspension of minute particles of metallic gold, made by exposure to neutrons. It is used in the pleural cavity to treat lung cancer. Pharmacological action: antineoplastic agent, radiopharmaceuticals. (12 Dec 1998) |
| rose bengal radioactive test | A test of liver function used as a means of measuring hepatic blood flow and for scintillation scanning of the liver to determine size and contour of the liver, or the presence of space-occupying masses in the liver. (05 Mar 2000) |
| water pollutants, radioactive | Pollutants, present in water or bodies of water, which exhibit radioactivity. (12 Dec 1998) |
| colloidal radioactive gold | A radioactive isotope of gold emitting negative beta particles and gamma radiation, with a half-life of 2.7 days; formerly used for irradiation of closed serous cavities in the palliative treatment of ascites and pleural effusion due to metastatic malignancies, and for liver scans. Synonym: 198Au colloid, colloidal radioactive gold. (05 Mar 2000) |
| soil pollutants, radioactive | Pollutants, present in soil, which exhibit radioactivity. (12 Dec 1998) |
| elements, radioactive | Chemical elements which spontaneously transmute into another element with corpuscular or electromagnetic radiation. The natural radioactive elements are all those with an atomic number above 83, and some other elements, such as potassium (atomic number 19) and rubidium (atomic number 7), which are very weakly radioactive. (12 Dec 1998) |
| air | 1. The fluid which we breathe, and which surrounds the earth; the atmosphere. It is invisible, inodourous, insipid, transparent, compressible, elastic, and ponderable. By the ancient philosophers, air was regarded as an element; but modern science has shown that it is essentially a mixture of oxygen and nitrogen, with a small amount of carbon dioxide, the average proportions being, by volume: oxygen.96 per cent.; nitrogen.00 per cent.; carbon dioxide.04 per cent. These proportions are subject to a very slight variability. Air also always contains some vapor of water. 2. Symbolically: Something unsubstantial, light, or volatile. "Charm ache with air." "He was still all air and fire. (Macaulay). [Air and fire being the finer and quicker elements as opposed to earth and water]" 3. A particular state of the atmosphere, as respects heat, cold, moisture, etc, or as affecting the sensations; as, a smoky air, a damp air, the morning air, etc. 4. Any aeriform body; a gas; as, oxygen was formerly called vital air. 5. Air in motion; a light breeze; a gentle wind. "Let vernal airs through trembling osiers play." (Pope) 6. Odouriferous or contaminated air. 7. That which surrounds and influences. "The keen, the wholesome air of poverty." (Wordsworth) 8. Utterance abroad; publicity; vent. "You gave it air before me." (Dryden) 9. Intelligence; information. 10. A musical idea, or motive, rhythmically developed in consecutive single tones, so as to form a symmetrical and balanced whole, which may be sung by a single voice to the stanzas of a hymn or song, or even to plain prose, or played upon an instrument; a melody; a tune; an aria. In harmonised chorals, psalmody, part songs, etc, the part which bears the tune or melody in modern harmony usually the upper part is sometimes called the air. 11. The peculiar look, appearance, and bearing of a person; mien; demeanor; as, the air of a youth; a heavy air; a lofty air. "His very air." 12. Peculiar appearance; apparent character; semblance; manner; style. "It was communicated with the air of a secret." (Pope) 12. An artificial or affected manner; show of pride or vanity; haughtiness; as, it is said of a person, he puts on airs. 14. The representation or reproduction of the effect of the atmospheric medium through which every object in nature is viewed. Carriage; attitude; action; movement; as, the head of that portrait has a good air. 15. The artificial motion or carriage of a horse. 16. To expose to the air for the purpose of cooling, refreshing, or purifying; to ventilate; as, to air a room. "It were good wisdom . . . That the jail were aired." (Bacon) "Were you but riding forth to air yourself." (Shak) 17. To expose for the sake of public notice; to display ostentatiously; as, to air one's opinion. "Airing a snowy hand and signet gem." (Tennyson) 18. To expose to heat, for the purpose of expelling dampness, or of warming; as, to air linen; to air liquors. Air is much used adjectively or as the first part of a compound term. In most cases it might be written indifferently, as a separate limiting word, or as the first element of the compound term, with or without the hyphen; as, air bladder, air-bladder, or airbladder; air cell, air-cell, or aircell; air-pump, or airpump. Air balloon. See Balloon. Air bath. An apparatus for the application of air to the body. An arrangement for drying substances in air of any desired temperature. Air castle. See Castle in the air, under Castle. Air compressor, a machine for compressing air to be used as a motive power. Air crossing, a passage for air in a mine. Air cushion, an air-tight cushion which can be inflated; also, a device for arresting motion without shock by confined air. Air fountain, a contrivance for producing a jet of water by the force of compressed air. Air furnace, a furnace which depends on a natural draft and not on blast. Air line, a straight line; a bee line. Hence Air-line,; as, air-line road. <medicine> Air lock Unsupported and liable to be turned or taken in flank; as, the army had its wing in the air. To take air, to be divulged; to be made public. To take the air, to go abroad; to walk or ride out. Origin: OE. Air, eir, F. Air, L. Aer, fr. Gr, air, mist, for, fr. Root to blow, breathe, probably akin to E. Wind. In sense 10 the French has taking a meaning fr. It. Aria atmosphere, air, fr. The same Latin word; and in senses 11, 12, 13 the French meaning is either fr. L. Aria, or due to confusion with F. Aire, in an older sense of origin, descent. Cf. Ary, Debonair, Malaria, Wind. Source: Websters Dictionary (01 Mar 1998) |
| air ambulances | Fixed-wing aircraft or helicopters equipped for air transport of patients. (12 Dec 1998) |
| air bags | Automotive safety devices consisting of a bag designed to inflate upon collision and prevent passengers from pitching forward. (12 Dec 1998) |