| condensation | <chemistry> The process whereby a gas becomes a liquid or a solid. A chemical reaction between two organic compounds which produces (among other things) water, ammonia, or a simple alcohol. A chemical reaction between two molecules which links them together and expels a molecule of water. For example: the joining of two amino acids by a peptide bond during the formation of a polypeptide. (05 Jan 1998) |
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| condensation compound | A compound resulting from the combination of two or more simple substances, with the splitting off of some other substance, such as alcohol or water; e.g., a peptide. Compare: conjugated compound. (05 Mar 2000) |
| condensation polymer | <chemistry> The kind of polymer that is formed by the combination of monomers and the release of a small molecules at the point where monomers are joined. (05 Jan 1998) |
| condense | To pack; to increase the density of; applied particularly to insertion of gold foil or silver amalgam in a cavity prepared in a tooth. (05 Mar 2000) |
| condensed milk | A thick liquid prepared by the partial evaporation of cow's milk, with or without the addition of sugar. (05 Mar 2000) |
| condenser | <microscopy> In microscopy, the lens mounted before the microscope stage, which transmits light to the object. There are two main categories of condensers: (1) bright field and (2) dark field. Bright field condensers are of four distinct types: (a) Abbe condenser,, an uncorrected condenser composed of two separable lenses, (b) aplanatic condenser, (c) achromatic condenser which has full corrections for colour and spherical aberrations, (d) aplanatic achromatic condenser. The dark field condenser for low powers may be nothing more than a low-power bright field condenser with a central stop. Medium- or high-powered dark field condensers are usually of the cardioid or paraboloid type. The lamp lens is loosely called a condenser lens, but light-collecting lens is a more definite term. All microscope condensers must be carefully focused and aligned for best results. (05 Aug 1998) |
| condenser circle | <microscopy> The image of the aperture iris diaphragm of the substage condenser as seen in the back focal plane of the objective. (05 Aug 1998) |
| condenser or condenser lens | <physics> A term applied to lenses or mirrors designed to collect, control, and concentrate radiation in an illumination system. (05 Aug 1998) |
| condenser, Abbe | <microscopy> Originally a two-lens substage condenser combination designed by Ernst Abbe. It lacks chromatic correction though designed for a minimum of spherical aberration and has only a very low-angle aplanatic cone. It may be rated with a numerical aperture as high as 1.3. (05 Aug 1998) |
| condenser, dark field | <microscopy> A condenser forming a hollow cone of light with its apex (or focal point) in the plane of the specimen. When used with an objective having a numerical aperture lower than the minimum numerical aperture of the hollow cone, only light deviated by the specimen enters the objective. Objects are seen as bright images against a dark background. The ordinary bright field condenser of low power, used with a central stop, makes a good dark field condenser. They all form a dark field while illuminating the specimen with a hollow cone of light. The lower limiting aperture of the condenser must be greater than the numerical aperture of the objective with which it is to be used. Thus, no direct light enters the objective, the specimen is seen by reflected or scattered light on a dark background. See: condensers See: special dark field condensers: paraboloid, cardioid and Cassegrainian. (05 Aug 1998) |
| condenser, darkfield, bispheric | <microscopy> A dark field condenser consisting of a convex spherical reflector mounted concentric with a larger concave reflector. The rays are formed into a diverging cone by the convex reflector. The annular concave reflector then forms a hollow converging cone which is focused on the subject. See (05 Aug 1998) |
| condenser, darkfield, paraboloid | <microscopy> A dark field condenser consisting of a reflecting surface in the form of a segment of a paraboloid of revolution. Parallel rays entering the condenser around the periphery of the central stop are reflected from the curved surfaces and converge at the focus of the paraboloid. See (05 Aug 1998) |
| condenser, variable-focus | <microscopy> Essentially an Abbe condenser in which the upper lens element is fixed and the lower movable. The lower lens may be used to focus the illumination between the elements so that it emerges from the stationary lens as a large diameter parallel bundle. The field of low-power objectives may thus be filled without removing the top element. at the opposite extreme it can be adjusted to have a numerical aperture as high as 1.3. See: illumination, critical. (05 Aug 1998) |
| condensing enzyme | Citrate (si)-synthase;an enzyme catalyzing the condensation of oxaloacetate, water, and acetyl-CoA, forming citrate and coenzyme A; an important step in the tricarboxylic acid cycle. Synonym: citrogenase, condensing enzyme, oxaloacetate transacetase. (05 Mar 2000) |
| condensing osteitis | Fusiform thickening or increased density of bones, of unknown cause; it has been considered a form of chronic nonsuppurative osteomyelitis. Synonym: condensing osteitis, Garre's disease. Osteitis tuberculosa multiplex cystica, an osteitis of tuberculous origin, marked by numerous small cavities in the osseous substance. Synonym: Jungling's disease. (05 Mar 2000) |