natural purification (자정 작용
| dental material | Any material used in dentistry. (05 Mar 2000) |
|---|---|
| discharge of dredged material | Any addition of dredged material into the waters of the U.S. The term includes, without limitation, the addition of dredged material to a specified discharge site located in waters of the U.S. And the runoff or overflow from a contained land or water disposal area. Discharges of pollutants into waters of the U.S., resulting from the onshore subsequent processing of dredged material that is extracted from any commercial use (other than fill), are not included within this term and are subject to Section 402 of the CWA even though the extraction and deposit of such material may require a permit from the Corps of Engineers. The term does not include plowing, cultivating, seeding, and harvesting for the production of food, fibre, and forest products. The term does not include de minimis, incidental soil movement occurring during normal dredging operations. (09 Oct 1997) |
| discharge of fill material | The addition of fill material into waters of the U.S. The term generally includes, without limitation, the following activities: placement of fill that is necessary for the construction of any structure in a water of the U.S., the building of any structure or impoundment requiring rock, sand, dirt, or other material for its construction, site-development fills for recreational, industrial, commercial, residential, and other uses, causeways or road fills, dams and dikes, artificial islands, property protection and/or reclamation devices such as riprap, groins, seawalls, breakwaters, and revetments, beach nourishment, levees, fill for structures such as sewage treatment facilities, intake and outfall pipes associated with power plants and subaqueous utility lines, and artificial reefs. The term does not include plowing, cultivating, seeding, and harvesting for the production of food, fibre, and forest products. (09 Oct 1997) |
| impression material | Any substance or combination of substances used for making a negative reproduction or impression. (05 Mar 2000) |
| iodinated contrast material | A substance that contains iodine that can be injected, swallowed or given as an enema for the purpose of diagnostics. Iodinated contrast is radiopaque. This means that conventional X-rays will highlight the course of the contrast in the body. (27 Sep 1997) |
| type material | <zoology> A collective term for all type specimens. Zoologists should ensure that such material is transferred as quickly as possible to public institutions where their safety is guaranteed and they are accessible to other workers. (09 Jan 1998) |
| unconsolidated parent material | <ecology> Material from which a soil develops. (09 Oct 1997) |
| fertile material | <physics> In nuclear physics, this refers to a nuclide which converts to fissile material upon neutron capture and subsequent radioactive decay. Examples include Uranium-238 and Thorium-232. (09 Oct 1997) |
| fill material | Any material used for the primary purpose of replacing an aquatic area with dry land or of changing the bottom elevation of a waterbody. The term does not include any pollutant discharged into the water primarily to dispose of waste. (09 Oct 1997) |
| fissile material | <radiobiology> Material containing a large number of easily fissionable nuclei which give off multiple neutrons in the fission process. Usual meaning is that if a sufficiently large amount of fissile material is put together, a fission chain reaction can occur. Sometimes used synonymously with fissionable material, i.e., material that can be fissioned (though often under restricted circumstances, such as only with thermal (slow) neutrons). A more restricted meaning use of fissile material limits the concept to those materials which can be fissioned by neutrons of all energies (fast & slow). Examples include Uranium-235 and Plutonium-239. (09 Oct 1997) |
| conservation of natural resources | The protection, preservation, restoration, and rational use of all resources in the total environment. (12 Dec 1998) |
| natural | 1. Fixed or determined by nature; pertaining to the constitution of a thing; belonging to native character; according to nature; essential; characteristic; not artifical, foreign, assumed, put on, or acquired; as, the natural growth of animals or plants; the natural motion of a gravitating body; natural strength or disposition; the natural heat of the body; natural colour. "With strong natural sense, and rare force of will." (Macaulay) 2. Conformed to the order, laws, or actual facts, of nature; consonant to the methods of nature; according to the stated course of things, or in accordance with the laws which govern events, feelings, etc.; not exceptional or violent; legitimate; normal; regular; as, the natural consequence of crime; a natural death. "What can be more natural than the circumstances in the behavior of those women who had lost their husbands on this fatal day?" (Addison) 3. Having to do with existing system to things; dealing with, or derived from, the creation, or the world of matter and mind, as known by man; within the scope of human reason or experience; not supernatural; as, a natural law; natural science; history, theology. "I call that natural religion which men might know . By the mere principles of reason, improved by consideration and experience, without the help of revelation." (Bp. Wilkins) 4. Conformed to truth or reality; as: Springing from true sentiment; not artifical or exaggerated; said of action, delivery, etc.; as, a natural gesture, tone, etc. Resembling the object imitated; true to nature; according to the life; said of anything copied or imitated; as, a portrait is natural. 5. Having the character or sentiments properly belonging to one's position; not unnatural in feelings. "To leave his wife, to leave his babes, . He wants the natural touch." (Shak) 6. Connected by the ties of consanguinity. "Natural friends." 7. Begotten without the sanction of law; born out of wedlock; illegitimate; bastard; as, a natural child. 8. Of or pertaining to the lower or animal nature, as contrasted with the higher or moral powers, or that which is spiritual; being in a state of nature; unregenerate. "The natural man receiveth not the things of the Spirit of God." (1 Cor. Ii. 14) 9. <mathematics> Belonging to, to be taken in, or referred to, some system, in which the base is 1; said or certain functions or numbers; as, natural numbers, those commencing at 1; natural sines, cosines, etc, those taken in arcs whose radii are 1. 10. Produced by natural organs, as those of the human throat, in distinction from instrumental music. Of or pertaining to a key which has neither a flat nor a sharp for its signature, as the key of C major. Applied to an air or modulation of harmony which moves by easy and smooth transitions, digressing but little from the original key. Natural day, the space of twenty-four hours. Natural fats, Natural gas, etc. See Fat, Gas. Etc. Natural Harmony, a classification based upon real affinities, as shown in the structure of all parts of the organisms, and by their embryology. "It should be borne in mind that the natural system of botany is natural only in the constitution of its genera, tribes, orders, etc, and in its grand divisions." (Gray) Natural theology, or Natural religion, that part of theological science which treats of those evidences of the existence and attributes of the Supreme Being which are exhibited in nature; distinguished from revealed religion. See Quotation under Natural. Natural vowel, the vowel sound heard in urn, furl, sir, her, etc.; so called as being uttered in the easiest open position of the mouth organs. See Neutral vowel. Synonym: See Native. Origin: OE. Naturel, F. Naturel, fr. L. Naturalis, fr. Natura. See Nature. Source: Websters Dictionary (01 Mar 1998) |
| natural antibody | Antibody demonstrable in the serum or plasma of various persons or animals not known to have been stimulated by specific antigen, either artificially or as the result of naturally occurring contact. Synonym: natural antibody. (05 Mar 2000) |
| natural childbirth | Psychophysical relaxation techniques that are used to facilitate childbirth. (12 Dec 1998) |
| natural classification | <zoology> Classification based on inferences concerning the phylogenetic relationships of animals. (09 Jan 1998) |