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dialysis

(Encyclopedia)dialysis dīălˈĭsĭs [key], in chemistry, transfer of solute (dissolved solids) across a semipermeable membrane. Strictly speaking, dialysis refers only to the transfer of the solute; transfer of t...

covenant

(Encyclopedia)covenant kŭvˈənənt [key], agreement entered into voluntarily by two or more parties to do or refrain from doing certain acts. In the Bible and in theology the covenant is the agreement or engageme...

chain reaction

(Encyclopedia)CE5 Chain reaction: A neutron (n) strikes the uranium nucleus (U-235), causing it to split into fission products A and B and release two neutrons. These neutrons can in turn cause further fissions....

etching

(Encyclopedia)etching, the art of engraving with acid on metal; also the print taken from the metal plate so engraved. In hard-ground etching the plate, usually of copper or zinc, is given a thin coating or ground ...

embryo screening

(Encyclopedia)embryo screening, procedure (see genetic testing) in which a single cell is removed from an embryo two or three days after it has been conceived through in vitro fertilization and tested for genetic a...

spring, in geology

(Encyclopedia)spring, in geology, natural flow of water from the ground or from rocks, representing an outlet for the water that has accumulated in permeable rock strata underground. Some of the water that falls as...

license

(Encyclopedia)license, in public law, permission by legal authority to engage in certain acts and also the document showing such permission. Some licenses are required for the protection of the public; they assure ...

John of Austria, 1545–78, Spanish admiral and general

(Encyclopedia)John of Austria, 1545–78, Spanish admiral and general; illegitimate son of Holy Roman Emperor Charles V. He was acknowledged in his father's will and was recognized by his half-brother, Philip II of...

Hastings, city, England

(Encyclopedia)Hastings, city and district, East Sussex, SE England. A resort and residential city, Hastings is backed by cliffs and has a 3-mi (4.8-km) marine esplana...

half-life

(Encyclopedia)half-life, measure of the average lifetime of a radioactive substance (see radioactivity) or an unstable subatomic particle. One half-life is the time required for one half of any given quantity of th...