| non-ionic contrast media | <radiology> A class of radiographic contrast media which do not ionise in solution, thereby decreasing effective osmolarity and toxicity. (05 Mar 2000) |
|---|---|
| ionic | Relating to an ion. (05 Mar 2000) |
| ionic coupling | <chemistry> The same as electrical coupling. (18 Nov 1997) |
| ionic medication | Movement of ions as a result of an applied electric field. For example the delivery of a charged molecule from the end of a micropipette without hydraulic flow. (18 Nov 1997) |
| ionic strength | Symbolised as g/2 or I and set equal to 0.5σmizi2, where mi equals the molar concentration and zi the charge of each ion present in solution; if molar concentrations (ci) are used instead of molality (and the solution is dilute), then I == 0.5(1/ρo)σcizi2 where ρo is the density of the solvent; a number of biochemically important events (e.g., protein solubility and rates of enzyme action) vary with the ionic strength of a solution. (05 Mar 2000) |
| alveolar gas equation | The equation defining the steady state relation of the alveolar oxygen pressure to the barometric pressure, inspired gas composition, alveolar carbon dioxide pressure, and respiratory exchange ratio; the equation is used in various forms depending upon which simplifying assumptions are acceptable for different applications. (05 Mar 2000) |
| arrhenius equation | This equation expresses the logarithmic relationship between the rate constant of a reaction and the reciprocal of the temperature (expressed in K). (09 Oct 1997) |
| Bohr's equation | An equation to calculate the respiratory dead space from the fact that gas expired from the lungs is a mixture of gas from the dead space and gas from the alveoli, i.e., the dead space volume divided by the tidal volume equals the difference between alveolar and mixed expired gas composition, divided by the difference between alveolar and inspired gas composition; gas composition can be expressed in any consistent units of concentration or partial pressure of oxygen or carbon dioxide. (05 Mar 2000) |
| boltzmann equation | <radiobiology> Fundamental equation in kinetic theory which describes the evolution of the distribution function. (See also Vlasov equation.) The actual equation is given in most texts covering plasma kinetic theory. (09 Oct 1997) |
| van't Hoff's equation | Equation for osmotic pressure of dilute solutions. See: van't Hoff's law. For any reaction, d(ln Keq/d(1/T) equals -dH/R where Keq is the equilibrium constant, T the absolute temperature, R is the universal gas constant, and dH is the change in enthalpy; thus, plotting ln Keq vs. 1/T allows the determination of dH. (05 Mar 2000) |
| Gay-Lussac's equation | The overall chemical equation for alcoholic fermentation; C6H12O6 = 2CO2 + 2CH3CH2OH. (05 Mar 2000) |
| rate equation | A mathematical expression for a chemical, radiochemical, or enzyme-catalyzed reaction. (05 Mar 2000) |
| Rayleigh equation | A ratio of red to green required by each observer to match spectral yellow. Synonym: Rayleigh test. (05 Mar 2000) |
| Gibbs-Helmholtz equation | An equation expressing the relationship in a galvanic cell between the chemical energy transformed and the maximal electromotive force obtainable. (05 Mar 2000) |
| Victor-Michaelis-Menten equation | <chemistry> Equation derived from a simple kinetic model for a single-substrate non-cooperative enzyme-catalyzed reaction that successfully accounts for the hyperbolic adsorption isotherm) relationship between substrate concentration and reaction rate. V = Vmax x S/(S + Km), where V is the initial velocity of the reaction, Km is the Michaelis constant, Vmax is the maximum rate approached by very high substrate concentrations and S is the initial substrate concentration. Similar equations can be derived for conditions in which the product is present and for multisubstrate enzymes. Synonym: Victor-Michaelis-Menten equation. (12 Jul 2000) |