| Geigel, Richard | <person> German physician, 1859-1930. See: Geigel's reflex. (05 Mar 2000) |
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| Geiger, Hans | <person> German physicist, 1882-1945. See: Geiger-Muller counter, Geiger-Muller tube. (05 Mar 2000) |
| Geiger-Muller counter | <instrument> An instrument for measuring radioactivity by counting the emission of radioactive particles. It consists of a metallic cylinder, negatively charged, in a tube containing a fine, positively charged wire at its centre; radiations produce ionization of the gas molecules between the cylinder and the wire and result in an electrical discharge independent of the energy of the impinging particle or ray. (05 Mar 2000) |
| Geiger-Muller tube | <instrument> An instrument for measuring radioactivity by counting the emission of radioactive particles. It consists of a metallic cylinder, negatively charged, in a tube containing a fine, positively charged wire at its centre; radiations produce ionization of the gas molecules between the cylinder and the wire and result in an electrical discharge independent of the energy of the impinging particle or ray. (05 Mar 2000) |
| gein | <chemistry> See Humin. Origin: Gr. Earth. Source: Websters Dictionary (01 Mar 1998) |
| geissler tube | <physics> A glass tube provided with platinum electrodes, and containing some gas under very low tension, which becomes luminous when an electrical discharge is passed through it; so called from the name of a noted maker in germany. It is called also Plucker tube, from the German physicist who devised it. Source: Websters Dictionary (01 Mar 1998) |
| geitonogamy | <botany> Fertilization of flowers by pollen from other flowers on the same plant. Origin: Gr. Neighbor + marriage. Source: Websters Dictionary (01 Mar 1998) |
| gel | Jelly like material formed by the coagulation of a colloidal liquid. Many gels have a fibrous matrix and fluid filled interstices: gels are viscoelastic rather than simply viscous and can resist some mechanical stress without deformation. Examples are the gels formed by large molecules such as collagen (and gelatin), agarose, acrylamide and starch. (18 Nov 1997) |
| gel diffusion | Diffusion in a gel, as in the case of gel diffusion precipitin tests in which the immune reactants diffuse in agar. See: immunodiffusion. (05 Mar 2000) |
| gel diffusion precipitin tests | Precipitin test's in which the immune precipitate forms in a gel medium (usually agar) into which one or both reactants have diffused; generally classified in two types, in one dimension, and in two dimensions. Synonym: gel diffusion reactions. (05 Mar 2000) |
| gel diffusion precipitin tests in one dimension | Precipitin test's in which antigen solution and antibody incorporated in agar are layered in tubes, permitting effective diffusion in the vertical dimension; the antibody-containing agar may be overlaid directly with antigen solution (single (gel) diffusion in one dimension). (05 Mar 2000) |
| gel diffusion precipitin tests in two dimensions | Precipitin test's made in a layer of agar that permits radial diffusion, in both of the horizontal dimensions, of one or both reactants. Double (gel) diffusion in two dimensions (Ouchterlony test, technique, or method) incorporates antigen and antibody solutions placed in separate wells in a sheet of plain agar, permitting radial diffusion of both reactants; this method is widely used to determine antigenic relationships; the bands of precipitate that form where the reactants meet in optimal concentration are of three patterns, referred to as reaction of identity, reaction of partial identity (cross-reaction), and reaction of nonidentity. (05 Mar 2000) |
| gel diffusion reactions | Precipitin test's in which the immune precipitate forms in a gel medium (usually agar) into which one or both reactants have diffused; generally classified in two types, in one dimension, and in two dimensions. Synonym: gel diffusion reactions. (05 Mar 2000) |
| gel electrophoresis | <molecular biology> Electrophoresis using a gel supporting phase. Usually applied to systems where the gel is based on polyacrylamide. See: electrophoresis. (05 May 1997) |
| gel exclusion chromatography | <investigation> A lab technique, a type of column chromatography, used to separate the components of a mixture by molecular size and to collect the molecules which are larger than a certain size. It is similar to gel filtration, small molecules are slowed or trapped by the pores in the gel beads filling the column, while large molecules, too large to fit into the pores, slide past the beads and get to the bottom of the column first. at this point, the large molecules are collected. Gel exclusion refers to the maximum size of molecule which will fit into the gel bead pores, and this lab technique is used to collect the molecules in the mixture which are larger than, or excluded from, the pores. (09 Oct 1997) |