| oxidation-reduction potential | <chemistry, physics> The potential in volts of an inert metallic electrode measured in a system of an arbitrarily chosen ratio of [oxidant] to [reductant] and referred to the normal hydrogen electrode at absolute temperature. It is calculated from the following equation: where R is the gas constant expressed in electrical units, T the absolute temperature (Kelvin), n the number of electrons transferred, F the faraday and E0 the normal symbol for the potential of the system at pH 0; for biological systems E0' is often used (in which pH = 7). Compare: Nernst's equation. Synonym: redox potential. (05 Mar 2000) |
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| algal oxidation pond | <ecology> A wide, shallow pond used in waste water treatment, the algae produce oxygen so that bacteria can aerobically digest sewage in the water. (09 Oct 1997) |
| alpha-oxidation | A form of oxidation of fatty acids in which carbons are removed one at a time in the form of CO2; the alpha-carbon is first hydroxylated and then converted into a carbonyl; a deficiency of this pathway is associated with Refsum's disease. (05 Mar 2000) |
| auto-oxidation | The direct combination of a substance with molecular oxygen at ordinary temperatures. Synonym: autoxidation. (05 Mar 2000) |
| beta-oxidation | <biochemistry> The oxidative breakdown of fatty acids into acetyl-coenzyme A by repeated oxidation at the beta-carbon atom. Oxidation of the beta-carbon (carbon 3) of a fatty acid causes the formation of the beta-keto (beta-oxo) acid analog. This is of importance in fatty acid catabolism, the entire pathway for the catabolism of saturated fatty acids containing an even number of carbon atoms. Beta-oxidation is a part of this pathway and acetyl-CoA is a major product of this pathway. (05 Mar 2000) |
| beta-oxidation-condensation theory | <biochemistry> That the two carbon fragments split from the fatty acid molecule by beta-oxidation are converted to acetic acid and then condensed to acetoacetic acid. (05 Mar 2000) |
| biological oxidation | Decomposition of organic materials by microorganisms. (05 Dec 1998) |
| biological standard unit | A specific quantity of biologically active reference material (antibiotic, antitoxin, enzyme, hormone, vitamin, etc.). (05 Mar 2000) |
| gold standard | Term used to describe a method or procedure that is widely recognised as the best available. Origin: jargon (05 Mar 2000) |
| Meyerhof oxidation quotient | <biochemistry> An index for the effect of oxygen on glycolysis and on fermentation (i.e., on the Pasteur effect); equal to the rate of anaerobic fermentation minus the rate of aerobic respiration divided by the rate of oxygen uptake. (21 Jun 2000) |
| pyruvate oxidation factor | <biochemistry> 1,2 dithiolane 3 valeric acid. Regarded as a coenzyme in the oxoglutarate dehydrogenase complex of the citric acid cycle. Involved generally in oxidative decarboxylations of _ keto acids. A growth factor for some organisms. (18 Nov 1997) |
| standard | 1. A flag; colours; a banner; especially, a national or other ensign. "His armies, in the following day, On those fair plains their standards proud display." (Fairfax) 2. That which is established by authority as a rule for the measure of quantity, extent, value, or quality; especially, the original specimen weight or measure sanctioned by government, as the standard pound, gallon, or yard. 3. That which is established as a rule or model by authority, custom, or general consent; criterion; test. "The court, which used to be the standard of property and correctness of speech." (Swift) "A disposition to preserve, and an ability to improve, taken together, would be my standard of a statesman." (Burke) 4. The proportion of weights of fine metal and alloy established by authority. "By the present standard of the coinage, sixty-two shillings is coined out of one pound weight of silver." (Arbuthnot) 5. <botany> A tree of natural size supported by its own stem, and not dwarfed by grafting on the stock of a smaller species nor trained upon a wall or trellis. "In France part of their gardens is laid out for flowers, others for fruits; some standards, some against walls." (Sir W. Temple) 6. <botany> The upper petal or banner of a papilionaceous corolla. 7. <mechanics> An upright support, as one of the poles of a scaffold; any upright in framing. 8. An inverted knee timber placed upon the deck instead of beneath it, with its vertical branch turned upward from that which lies horizontally. 9. The sheth of a plow. 10. A large drinking cup. Standard bearer, an officer of an army, company, or troop, who bears a standard; commonly called colour sergeantor colour bearer; hence, the leader of any organization; as, the standard bearer of a political party. Origin: OF. Estendart, F. Etendard, probably fr. L. Extendere to spread out, extend, but influenced by E. Stand. See Extend. 1. Being, affording, or according with, a standard for comparison and judgment; as, standard time; standard weights and measures; a standard authority as to nautical terms; standard gold or silver. 2. Hence: Having a recognised and permanent value; as, standard works in history; standard authors. 3. <botany> Not supported by, or fastened to, a wall; as, standard fruit trees. Not of the dwarf kind; as, a standard pear tree. Standard candle, Standard gauge. See Candle, and Gauge. Standard solution. <chemistry> See Standardized solution, under Solution. Source: Websters Dictionary (01 Mar 1998) |
| standard atmosphere | The pressure of the atmosphere at mean sea level, equivalent to 1,013,250 dynes/cm2 or 101,325 Pa (N/m2 in the SI system), a standardised expression of the relation of barometric pressure, temperature, and other atmospheric variables as a function of altitude above sea level. (05 Mar 2000) |
| standard cell | An electrical cell having a definite known voltage; used to calibrate other electric cell's. (05 Mar 2000) |
| standard deviation | Statistical index of the degree of deviation from central tendency, namely, of the variability within a distribution; the square root of the average of the squared deviation's from the mean. A measure of dispersion or variation used to describe a characteristic of a frequency distribution. (05 Mar 2000) |