| cathodal opening contraction | An obsolete term for the momentary contraction of a muscle under the influence of the negative pole when the circuit is broken. (05 Mar 2000) |
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| cathodal opening tetanus | An obsolete term for a tonic contraction in a muscle, to which the cathode is applied; when the circuit is opened, the contraction is suddenly interrupted. (05 Mar 2000) |
| cathode | <chemistry, physics> The electrode in an electrochemical cell toward which cations are drawn and where reduction occurs. The negatively charged electrode in a vacuum tube. (16 Mar 1998) |
| cathode ray | <physics> Electrons emitted from the surface of a cathode in a vacuum tube. (16 Mar 1998) |
| cathode ray tube | An evacuated tube containing a beam of electrons which can be deflected to various parts of a fluorescent screen; used in the cathode ray oscilloscope. (05 Mar 2000) |
| cathode rays | A stream of electrons emitted from the negative electrode (cathode) in a Crookes tube; their bombardment of the anode or the glass wall of the tube gives rise to X-ray's. (05 Mar 2000) |
| cathodic | Of, pertaining to, or emanating from a cathode. Synonym: cathodic. (05 Mar 2000) |
| cathodic protection | <chemistry> The attachment of an active metal to a system to protect the system from corrosion. The active metal serves as the anode, making the metal in the system a cathode. (16 Mar 1998) |
| catholicism | The christian faith, practice, or system of the catholic church, specifically the roman catholic, the christian church that is characterised by a hierarchic structure of bishops and priests in which doctrinal and disciplinary authority are dependent upon apostolic succession, with the pope as head of the episcopal college. (12 Dec 1998) |
| catholysis | Electrolysis with a cathode needle. (05 Mar 2000) |
| cation | <chemistry> A positively-charged ion. (16 Mar 1998) |
| cation exchange | The process by which a cation in a liquid phase exchanges with another cation present as the counter-ion of a negatively charged solid polymer (cation exchanger). A cation-exchange reaction in removal of the Na+ of a sodium chloride solution is RSO3-H+ + Na+ → RSO3-Na+ + H+ (R is the polymer, RSO3- is the cation exchanger); if this is combined with the anion-exchange reaction, NaCl is removed from the solution (desalting). Cation exchange may also be used chromatographically, to separate cations, and medicinally, to remove a cation; e.g., H+, from gastric contents, or Na+ and K+ in the intestine. See: anion exchange. (05 Mar 2000) |
| cation exchange resins | High molecular weight insoluble polymers which contain functional cationic groups that are capable of undergoing exchange reactions; used in various types of chromatography; also to treat hyperkalaemia. (12 Dec 1998) |
| cation exchanger | An insoluble solid (usually a polystyrene or a polysaccharide) that has negatively charged radicals attached to it (e.g., -COO-, -SO3-), which can attract and hold cations that pass by in a moving solution if these are more attracted to the acid groups than the counter ion present. (05 Mar 2000) |
| cation exhange resin | <chemistry> An insoluble resin with fixed anionic groups which is used in chromatography to separate cationic molecules. (16 Mar 1998) |