| atomic number | <chemistry> Symbol Z. The number of protons in the nucleus of an atom and also its characteristic atomic number. The atomic numbers of the known elements form a complete series from 1 (hydrogen) to 103 (lawrencium). (16 Dec 1997) |
|---|---|
| Avogadro's number | <physics> The number of molecules in a mole (gram molecular weight) of a substance, equals 6.02 x 1023 molecules. (09 Oct 1997) |
| Brinell hardness number | A number related to the size of the permanent impression made by a ball indenter of specified size (usually 10 mm in diameter) pressed into the surface of the material under a specified load: where P = applied load in kg, D = diameter of the ball in mm, and d = diameter of the impression in mm. (05 Mar 2000) |
| burst number | The number of viral particles that emerge from a cell after a viralinfection has burst it open. (09 Oct 1997) |
| Mach number | A number representing the ratio between the speed of an object moving through a fluid medium, such as air, and the speed of sound in the same medium. (05 Mar 2000) |
| magnetic mach number | <physics> A dimensionless number equal to the ratio of the velocity of a fluid to the velocity of Alfven waves in that fluid. (13 Nov 1997) |
| mass number | The mass of the atom of a particular isotope relative to hydrogen-1 (or to 1/12 the mass of carbon-12), generally very close to the whole number represented by the sum of the protons and neutrons in the atomic nucleus of the isotope (indicated in the name or symbol of the isotope; e.g., oxygen-16, 16O); not to be confused with the atomic weight of an element, which may include a number of isotopes in natural proportion. (05 Mar 2000) |
| Reichert-Meissl number | An index of the volatile acid content of a fat; the number of milliliters of 0.1 n KOH required to neutralise the soluble volatile fatty acids in 5 g of fat that has been saponified, acidified to liberate the fatty acids, and then steam-distilled. Synonym: volatile fatty acid number. (05 Mar 2000) |
| volatile fatty acid number | An index of the volatile acid content of a fat; the number of milliliters of 0.1 n KOH required to neutralise the soluble volatile fatty acids in 5 g of fat that has been saponified, acidified to liberate the fatty acids, and then steam-distilled. Synonym: volatile fatty acid number. (05 Mar 2000) |
| gold number | A unit of power of the protective colloids; the number of milligrams of protective colloid just sufficient to prevent the precipitation of 10 ml of a 0.0053 to 0.0058% gold solution by the action of 1 ml of a 10% sodium chloride solution. Synonym: gold number. (05 Mar 2000) |
| Reynolds number | A dimensionless number that describes the tendency for a flowing fluid, such as blood, to change from laminar flow to turbulent flow or vice versa. (05 Mar 2000) |
| Reynold's number | <physiology> A constant without dimensions that relates the inertial and viscous drag acting to hinder a body moving through fluid medium. For cells the Reynold's number is very small, viscous drag is dominant and inertial resistance can be neglected. (18 Nov 1997) |
| MIM number | The catalog assignment for a mendelian trait in the MIM system. If the initial digit is 1, the trait is deemed autosomal dominant; if 2, autosomal recessive; if 3, then X-linked. Wherever a trait defined in this dictionary has a MIM number the number from the tenth edition of MIM is given in square brackets with or without an asterisk as appropriate e.g., Pelizaeus-Merzbacher disease is a well-established, autosomal, dominant, mendelian disorder. (05 Mar 2000) |
| wave number | <microscopy> The number of waves or cycles of light flux or radiant energy, measured through a distance of 1 cm. (05 Aug 1998) |
| writhing number | <molecular biology> The number of times the axis of a DNA helix crosses itself while the molecule is in the process of supercoiling. (09 Oct 1997) |