critical pressure gradient
61High performance liquid chromatography — Infobox chemical analysis name = High performance liquid chromatography caption =A HPLC. From left to right: A pumping device generating a gradient of two different solvents, a steel enforced column and an apparatus for measuring the absorbance.… …
62nervous system — Anat., Zool. 1. the system of nerves and nerve centers in an animal or human, including the brain, spinal cord, nerves, and ganglia. 2. a particular part of this system. Cf. autonomic nervous system, central nervous system, peripheral nervous… …
63United States — a republic in the N Western Hemisphere comprising 48 conterminous states, the District of Columbia, and Alaska in North America, and Hawaii in the N Pacific. 267,954,767; conterminous United States, 3,022,387 sq. mi. (7,827,982 sq. km); with… …
64metamorphic rock — Any of a class of rocks that result from the alteration of preexisting rocks in response to changing geological conditions, including variations in temperature, pressure, and mechanical stress. The preexisting rocks may be igneous, sedimentary,… …
65Mechanical ventilation — In architecture and climate control, mechanical or forced ventilation is the use of powered equipment, e.g. fans and blowers, to move air  see ventilation (architecture). Mechanical ventilation Intervention …
66chromatography — chromatographer, n. chromatographic /kreuh mat euh graf ik, kroh meuh teuh /, adj. chromatographically, adv. /kroh meuh tog reuh fee/, n. Chem. the separation of mixtures into their constituents by preferential adsorption by a solid, as a column… …
67sound — sound1 soundable, adj. /sownd/, n. 1. the sensation produced by stimulation of the organs of hearing by vibrations transmitted through the air or other medium. 2. mechanical vibrations transmitted through an elastic medium, traveling in air at a… …
68Sound — /sownd/, n. The, a strait between SW Sweden and Zealand, connecting the Kattegat and the Baltic. 87 mi. (140 km) long; 3 30 mi. (5 48 km) wide. Swedish and Danish, Oresund. * * * I Mechanical disturbance that propagates as a longitudinal wave… …
69solids, mechanics of — ▪ physics Introduction science concerned with the stressing (stress), deformation (deformation and flow), and failure of solid materials and structures. What, then, is a solid? Any material, fluid or solid, can support normal forces.… …
70Contour line — This article is about lines of equal value in maps and diagrams. For more meanings of the word contour , see Contour (disambiguation). The bottom part of the diagram shows some contour lines with a straight line running through the location of… …
