Columbia Encyclopedia

Search results

500 results found

molecular weight

(Encyclopedia)molecular weight, weight of a molecule of a substance expressed in atomic mass units (amu). The molecular weight may be calculated from the molecular formula of the substance; it is the sum of the ato...

Bergström, Sune Karl

(Encyclopedia)Bergström, Sune Karl so͞oˈnə, bĕrˈyəström [key], 1916–2004, Swedish biochemist, grad. Karolinska Institute (Ph.D., M.D., 1944). With his former pupil B. I. Samuelsson and John R. Vane, he wa...

Evans, Oliver

(Encyclopedia)Evans, Oliver, 1755–1819, American inventor, b. near Newport, Del. He joined his brothers in a flour-milling business in Wilmington, and after studying similar earlier devices, he developed, install...

rhythm, biological

(Encyclopedia)rhythm, biological, or biorhythm, cyclic pattern of physiological changes or changes in activity in living organisms, most often synchronized with daily, monthly, or annual cyclical changes in the env...

Vane, Sir John Robert

(Encyclopedia)Vane, Sir John Robert, 1927–2004, British pharmacologist, Ph.D. Oxford, 1953. With B. I. Samuelsson and Sune K. Bergström, Vane was awarded the 1982 Nobel Prize in Physiology or Medicine. The trio ...

prostaglandin

(Encyclopedia)prostaglandin prŏsˌtəglănˈdən [key], any of a group of about a dozen compounds synthesized from fatty acids in mammals as well as in lower animals. Prostaglandins are highly potent substances th...

fireproofing

(Encyclopedia)fireproofing, method of making normally combustible materials as nearly noncombustible as possible. Fireproofing generally applies to textiles and construction materials that are treated with a soluti...

solar wind

(Encyclopedia)solar wind, stream of ionized hydrogen—protons and electrons—with an 8% component of helium ions and trace amounts of heavier ions that radiates outward from the sun at high speeds. The continuous...

white dwarf

(Encyclopedia)white dwarf, in astronomy, a type of star that is abnormally faint for its white-hot temperature (see mass-luminosity relation). Typically, a white dwarf star has the mass of the sun and the radius of...

viscosity

(Encyclopedia)viscosity, resistance of a fluid to flow. This resistance acts against the motion of any solid object through the fluid and also against motion of the fluid itself past stationary obstacles. Viscosity...