| fluorinated hydrocarbon | A molecule which is almost entirely carbon and hydrogen, but has had at least one fluorine atom introduced to it that has replaced one of the hydrogen atoms. (09 Oct 1997) |
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| fluorine | <chemistry, element> A non-metallic, gaseous element, strongly acid or negative, or associated with chlorine, bromine, and iodine, in the halogen group of which it is the first member. It always occurs combined, is very active chemically, and possesses such an avidity for most elements, and silicon especially, that it can neither be prepared nor kept in glass vessels. If set free it immediately attacks the containing material, so that it was not isolated until 1886. It is a pungent, corrosive, colourless gas. Fluorine unites with hydrogen to form hydrofluoric acid, which is the agent employed in etching glass. It occurs naturally, principally combined as calcium fluoride in fluorite, and as a double fluoride of aluminium and sodium in cryolite. Atomic weight: 19 Abbreviation: F Origin: NL. Fluorina: cf. G. Fluorin, F. Fluorine. So called from its occurrence in the mineral fluorite. (30 Mar 1998) |
| fluorine compounds | Inorganic compounds that contain fluorine as an integral part of the molecule. (12 Dec 1998) |
| fluorine radioisotopes | Unstable isotopes of fluorine that decay or disintegrate emitting radiation. F atoms with atomic weights 17, 18, and 20-22 are radioactive fluorine isotopes. (12 Dec 1998) |
| fluorite | <chemical> Calcium fluoride, a mineral of many different colours, white, yellow, purple, green, red, etc, often very beautiful, crystallizing commonly in cubes with perfect octahedral cleavage; also massive. It is used as a flux. Some varieties are used for ornamental vessels. Also called fluor spar, or simply fluor. Source: Websters Dictionary (01 Mar 1998) |
| fluorite objective | Microscope objective corrected for spherical and chromatic aberration at two wavelengths. Better than an ordinary objective corrected at one wavelength but inferior to (and much cheaper than) a planapochromatic objective. (18 Nov 1997) |
| fluoro- | See: fluor-. (05 Mar 2000) |
| fluoro-2,4-dinitrobenzene | A reagent used to combine with the free NH2 group of the NH2-terminal amino acid residue in a peptide, thus marking this residue; the combined forms are known as DNP-proteins, Dnp-aminoacyl, etc., the fluorine having been replaced to leave a dinitrophenyl residue (DNP, Dnp, or N2Ph-) attached to the NH2 group. Synonym: Sanger's reagent. Acronym: FDNB (05 Mar 2000) |
| fluoroacetate-specific dehalogenase | <enzyme> Acts on fluoroacetamide at 0.1 the rate for fluoroacetate Registry number: EC 3.8.1.- Synonym: fluoroacetate-specific defluorinase, fac dehalogenase (26 Jun 1999) |
| fluorocarbons | Liquid perfluorinated carbon compounds which may or may not contain a hetero atom such as nitrogen, oxygen or sulfur, but do not contain another halogen or hydrogen atom. This concept includes fluorocarbon emulsions and fluorocarbon blood substitutes. (12 Dec 1998) |
| fluorochrome | 1. <chemistry> Those molecules that are fluorescent when appropriately excited, fluorochromes such as fluorescein or tetramethyl rhodamine are usually used in their isothiocyanate forms (FITC, TRITC). 2. <microscopy> Dyes which have little colouring effect under ordinary lighting conditions but which fluoresce when irradiated with ultraviolet radiation. (05 Aug 1998) |
| fluorochroming | 1. Tagging or "labeling" of antibody with a fluorescent dye so that it may be observed with a microscope (using ultraviolet light), as a means of studying the origin, distribution, and sites of reaction (with antigen) in tissues. 2. Microscopic detection of cellular and tissue chemical components (DNA, RNA, proteins, polysaccharides) with the aid of fluorochromes bound to these components. (05 Mar 2000) |
| fluorocyte | Term used occasionally for a reticulocyte that exhibits fluorescence. (05 Mar 2000) |
| fluorodeoxyuridylate | <chemical> 5-fluoro-2'-deoxyuridylate. An inhibitor of thymidylate synthetase. Formed from 5-fluorouracil or 5-fluorodeoxyuridine. Chemical name: 5'-Uridylic acid, 2'-deoxy-5-fluoro- (12 Dec 1998) |
| fluorodifen | <chemical> An agricultural herbicide which is a yellow, crystalline solid that melts at 92 degrees C. (09 Oct 1997) |