| gram-atomic weight | Atomic weight expressed in grams. Compare: mole. (05 Mar 2000) |
|---|---|
| microscopy, atomic force | Microscopy in which a probe systematically rides across the surface of a sample being scanned in a raster pattern. The vertical position is recorded as a spring attached to the probe rises and falls in response to peaks and valleys on the surface. A microcomputer keeps track of the vertical excursions as a function of the position of the probe in the horizontal plane and presents the sample's image. (12 Dec 1998) |
| absorption | The process of absorbing, specifically: 1. <physiology> The movement and uptake of substances (liquids and solutes) into cells or across tissues such as skin, intestine and kiidney tubules, by way of diffusion or osmosis. 2. <chemistry> The drawing of a gas or liquid into the pores of a permeable solid. 3. <psychology> The devotion of thought to one object or activity, with inattention to others. 4. <radiology> The taking up of energy by matter with which the radiation interacts. 5. <physics> The loss of (electromagnetic) energy to a medium. For instance, an electromagnetic wave which propagates through a plasma will set the electrons into motion. If the electrons make collisions with other particles, they will absorb net energy from the wave. 6. <immunology> A process in which an antigen or antibody is used to pull an analogous antigen or antibody out of a solution. Compare: adsorption. Origin: L. Absorptio (12 Nov 1997) |
| absorption band | The range of wavelengths or frequencies in the electromagnetic spectrum where radiant energy is absorbed by passage through a gaseous, liquid, or dissolved substance; it is exploited for analytical purposes in colourimetry or spectrophotometry, and is usually described in terms of the wavelength where maximum absorbance occurs (i.e., lambdamax). (05 Mar 2000) |
| absorption cell | A small glass chamber with parallel sides, in which absorption spectra of solutions can be obtained. (05 Mar 2000) |
| absorption chromatography | <investigation> Techniques for separating molecules based on differential absorption and elution. Term for separation methods involving flow of a fluid carrier over a nonmobile absorbing phase. (18 Nov 1997) |
| absorption coefficient | <physics> Measures the degree of wave absorption defined as the fraction of wave energy lost as the wave travels a unit distance. See: absorption. (15 Jan 1998) |
| absorption collapse | Pulmonary collapse due to rapid complete obstruction of a large bronchus. (05 Mar 2000) |
| absorption fever | An elevation of temperature often occurring, without other untoward symptoms, shortly after childbirth, assumed to be due to absorption of uterine discharges through abrasions of the vaginal wall. (05 Mar 2000) |
| absorption lines | The dark line's in the solar spectrum due to absorption by the solar and the earth's atmosphere; the phenomenon occurs because rays passing from an incandescent body through a colder medium are absorbed by elements in that medium. (05 Mar 2000) |
| absorption spectroscopy | <investigation> This is the use of a spectrophotometer to measure the ability of particles (solutes) in a solution to absorb light through a range of specific wavelengths. Every compound absorbs light differently, so absorption spectra can be used to identify compounds, measure concentrations, and determine reaction rates. (15 Jan 1998) |
| absorption spectrum | <chemistry> A graph of the amount of light a substance absorbs, plotted as a fuction of energy, frequency or wavelength. (15 Jan 1998) |
| parenteral absorption | Absorption by any route other than the alimentary tract. (05 Mar 2000) |
| mass energy absorption coefficient | <physics> The mass energy absorption coefficient, uen/p of a material for uncharged ionising particles is the product of the mass energy transfer coefficient, utr/p and (1 - g) where g is the fraction of the energy of secondary charged particles that is lost to bremsstrahlung in the material. (16 Dec 1997) |
| pathologic absorption | Parenteral absorption of any excremental or pathologic material into the bloodstream, e.g., pus, urine, bile, etc. (05 Mar 2000) |