| buffer | <biochemistry, chemistry> A system that acts to minimise the change in concentration of a specific chemical species in solution against addition or depletion of this species. PH buffers: weak acids or weak bases in aqueous solution. The working range is given by pKa +/ 1. Metal ion buffers: a metal ion chelator for example EDTA, partially saturated by the metal ion acts, as a buffer for the metal ion. (18 Nov 1997) |
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| buffer capacity | <chemistry> The ability of a buffer solution to absorb added alkali or acid while maintaining the solution's pH. (09 Oct 1997) |
| buffer index | The power of a substance in solution to absorb acid or alkali without change in pH; this is highest at a pH value equal to the pKa value of the acid of the buffer pair. See: buffer capacity. Synonym: buffer index. (05 Mar 2000) |
| buffer pair | An acid and its conjugate base (anion). (05 Mar 2000) |
| buffer value | The power of a substance in solution to absorb acid or alkali without change in pH; this is highest at a pH value equal to the pKa value of the acid of the buffer pair. See: buffer capacity. Synonym: buffer index. (05 Mar 2000) |
| buffer value of the blood | The ability of the blood to compensate for additions of acid or alkali without disturbance of the pH. (05 Mar 2000) |
| buffer zone | <ecology> An area of land separating two distinct land uses that acts to soften or mitigate the effects of one land use on the other. (09 Oct 1997) |
| riparian buffer | Riparian areas that are managed to protect the aquatic and riparian ecosystem. A riparian buffer protects water quality and temperature, habitat along the banks, upland habitat for aquatic and riparian species, and some or all of the floodplain. (05 Dec 1998) |
| secondary buffer | See: Hamburger's law. (05 Mar 2000) |
| dipolar buffer | Buffer whose structure can include opposite charges. Synonym: dipolar buffer. (05 Mar 2000) |
| zwitterionic buffer | Buffer whose structure can include opposite charges. Synonym: dipolar buffer. (05 Mar 2000) |
| action | 1. A process or condition of acting or moving, as opposed to rest; the doing of something; exertion of power or force, as when one body acts on another; the effect of power exerted on one body by another; agency; activity; operation; as, the action of heat; a man of action. "One wise in council, one in action brave." (Pope) 2. An act; a thing done; a deed; an enterprise. (pl): Habitual deeds; hence, conduct; behavior; demeanor. "The Lord is a Good of knowledge, and by him actions are weighed." (1 Sam. Ii. 3) 3. The event or connected series of events, either real or imaginary, forming the subject of a play, poem, or other composition; the unfolding of the drama of events. 4. Movement; as, the horse has a spirited action. 5. <mechanics> Effective motion; also, mechanism; as, the breech action of a gun. 6. <physiology> Any one of the active processes going on in an organism; the performance of a function; as, the action of the heart, the muscles, or the gastric juice. 7. Gesticulation; the external deportment of the speaker, or the suiting of his attitude, voice, gestures, and countenance, to the subject, or to the feelings. 8. The attitude or position of the several parts of the body as expressive of the sentiment or passion depicted. 9. A suit or process, by which a demand is made of a right in a court of justice; in a broad sense, a judicial proceeding for the enforcement or protection of a right, the redress or prevention of a wrong, or the punishment of a public offense. A right of action; as, the law gives an action for every claim. 10. A share in the capital stock of a joint-stock company, or in the public funds; hence, in the plural, equivalent to stocks. "The Euripus of funds and actions." (Burke) 11. An engagement between troops in war, whether on land or water; a battle; a fight; as, a general action, a partial action. 12. The mechanical contrivance by means of which the impulse of the player's finger is transmitted to the strings of a pianoforte or to the valve of an organ pipe. Chose in action the product of the mass of a body by the space it runs through, and its velocity. Synonym: Action, act. In many cases action and act are synonymous; but some distinction is observable. Action involves the mode or process of acting, and is usually viewed as occupying some time in doing. Act has more reference to the effect, or the operation as complete. "To poke the fire is an act, to reconcile friends who have quarreled is a praiseworthy action." (C. J. Smith) Origin: OF. Action, L. Actio, fr. Agere to do. See Act. Source: Websters Dictionary (01 Mar 1998) |
| action current | An electrical current induced in muscle fibres when they are effectively stimulated; normally it is followed by contraction. (05 Mar 2000) |
| action potential | <physiology> The sequential, electrochemical polarization and depolarisation that travels across the membrane of a nerve cell (neuron) in response to stimulation (touch, pain, cold, etc.) (09 Oct 1997) |
| action tremor | <neurology> A tremor which arises or which is intensified when a voluntary, coordinated movement is attempted. (18 Nov 1997) |