| Svedberg unit | A sedimentation constant of 1 × 10-13 seconds. (05 Mar 2000) |
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| Svedberg | <unit> A unit for measuring the rate at which a particle sediments in a centrifuge. The unit applied to the sedimentation coefficient of a particle in a high speed or ultracentrifuge. S= rate of sedimentation x 1/ rho exp2r Where rho is the speed of rotation in radians per second and r is the radius to a chosen point in the centrifuge tube. 1 Svedberg unit is defined as a velocity gradient of 10exp 13 seconds. Named after a pioneer of the ultracentrifuge. The units are nonadditive: a particle formed from two 5S particles will not have a sedimentation coefficient of 10S. (18 Nov 1997) |
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| Svedberg equation | See: sedimentation constant. (05 Mar 2000) |
| Svedberg of flotation | Characteristic sedimentation behaviour of a lipoprotein fraction of plasma in a centrifugal field in a medium of appropriate density, achieved by adding a salt or D2O to the plasma. Synonym: negative S, Svedberg of flotation. (05 Mar 2000) |
| Svedberg, Theodor | <person> Swedish chemist and Nobel laureate, 1884-1971. See: Svedberg equation, Svedberg of flotation, Svedberg unit. (05 Mar 2000) |
| absolute unit | A unit whose value is constant regardless of place or time and not derived from dependent on gravitation. (05 Mar 2000) |
| alexin unit | The smallest amount (highest dilution) of complement that will cause haemolysis of a unit of red blood cells in the presence of a haemolysin unit. Synonym: alexin unit. (05 Mar 2000) |
| Allen-Doisy unit | The quantity of oestrogen capable of producing in a spayed mouse a characteristic change in the vaginal epithelium, namely, disappearance of leukocytes and appearance of cornified cells, as determined by a vaginal smear; equal approximately to one-half of an estrone unit. Synonym: mouse unit. (05 Mar 2000) |
| amboceptor unit | haemolysin unit |
| androgen unit | The androgenic activity of 100 ug (0.1 mg) of crystalline androsterone as assayed by the comb growth response in capons. (05 Mar 2000) |
| antigen unit | The smallest amount of antigen that, in the presence of specific antiserum, will fix 1 complement unit. (05 Mar 2000) |
| antitoxin unit | A unit expressing the strength or activity of an antitoxin; in general, determined with reference to a preserved standard preparation of antitoxin. See: L doses. (05 Mar 2000) |
| antivenene unit | The amount of antivenum which, injected in the ear vein, will protect 1 g weight of rabbit against a fatal dose of snake venom. (05 Mar 2000) |
| atomic mass unit | <chemistry> One-twelfth the mass of a neutral atom of the most abundant isotope of carbon. (16 Dec 1997) |
| Bethesda unit | A measure of inhibitor activity: the amount of inhibitor that will inactivate 50% or 0.5 unit of a coagulation factor during the incubation period. Origin: Bethesda, MD (05 Mar 2000) |
| biological standard unit | A specific quantity of biologically active reference material (antibiotic, antitoxin, enzyme, hormone, vitamin, etc.). (05 Mar 2000) |