helium-bearing natural gas
51moon — mooner, n. moonless, adj. /moohn/, n. 1. the earth s natural satellite, orbiting the earth at a mean distance of 238,857 miles (384,393 km) and having a diameter of 2160 miles (3476 km). 2. this body during a particular lunar month, or during a… …
52Moon — /moohn/, n. Sun Myung /sun myung/, born 1920, Korean religious leader: founder of the Unification Church. * * * Sole natural satellite of Earth, which it orbits from west to east at a mean distance of about 238,900 mi (384,400 km). It is less… …
53Molten salt reactor — scheme. A molten salt reactor (MSR) is a type of nuclear fission reactor in which the primary coolant, or even the fuel itself is a molten salt mixture. MSRs run at higher temperatures than water cooled reactors for higher thermodynamic… …
54Nuclear fuel cycle — The nuclear fuel cycle, also called nuclear fuel chain, is the progression of nuclear fuel through a series of differing stages. It consists of steps in the front end, which are the preparation of the fuel, steps in the service period in which… …
55Environmental radioactivity — is produced by radioactive materials in the human environment. While some radioisotopes, such as strontium 90 (90Sr) and technetium 99 (99Tc), are only found on Earth as a result of human activity, and some, like potassium 40 (40K), are only… …
56chromatography — 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… …
57Laserdisc — Not to be confused with disk laser, a flat configuration solid state laser. Not to be confused with VCD, DVD, or Blu ray, optical disc formats employing digital video encoding. Not to be confused with CED, a coincident but incompatible analogue… …
58United States Constitution — P …
59particle accelerator — accelerator (def. 7). [1945 50] * * * Device that accelerates a beam of fast moving, electrically charged atoms (ions) or subatomic particles. Accelerators are used to study the structure of atomic nuclei (see atom) and the nature of subatomic… …
60space exploration — Investigation of the universe beyond Earth s atmosphere by means of manned and unmanned spacecraft. Study of the use of rockets for spaceflight began early in the 20th century. Germany s research on rocket propulsion in the 1930s led to… …
