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chalcedony

(Encyclopedia)chalcedony kălsĕdˈənē [key] [from Chalcedon], form of quartz the crystals of which are so minute that its crystalline structure cannot be seen except with the aid of a microscope. Chalcedony has ...

Dubochet, Jacques

(Encyclopedia)Dubochet, Jacques, 1942–, Swiss biophysicist and molecular biologist, Ph.D., Univ. of Geneva 1973. Dubochet was a researcher at the European Molecular Biology Laboratory in Heidelberg from 1978 to 1...

Nicol prism

(Encyclopedia)Nicol prism nĭkˈəl [key], optical device invented (1828) by William Nicol of Edinburgh. It consists essentially of a crystal of calcite, or Iceland spar, that is cut at an angle into two equal piec...

Claude, Albert

(Encyclopedia)Claude, Albert älbârrˈ klōd [key], 1899–1983, Belgian biologist, b. Longlier, M.D., Univ. of Liège, 1928. He joined the Rockefeller Institute (now Rockefeller Univ.) in 1929 and spent his entir...

Nilsson, Lennart

(Encyclopedia)Nilsson, Lennart lĕnˈnärt nĭlˈsôn [key], 1922–2017, Swedish photographer who made pioneering microphotographs of embryos and the human body. Nilsson began his career as a photojournalist, chro...

cyanobacteria

(Encyclopedia)cyanobacteria sīˌənōbăktĭrˈēə, sī-ănˌō– [key] or blue-green algae, photosynthetic bacteria that contain chlorophyll. For many years they were classified in the plant kingdom along with ...

Brownian movement

(Encyclopedia)Brownian movement or motion, zigzag, irregular motion exhibited by minute particles of matter when suspended in a fluid. The effect has been observed in all types of colloidal suspensions (see colloid...

Cutler, Manasseh

(Encyclopedia)Cutler, Manasseh mənăsˈə [key], 1742–1823, American clergyman, scientist, and one of the organizers of the Ohio Company of Associates, b. Killingly, Conn. A student of both law and theology, he ...

protoplasm

(Encyclopedia)protoplasm, term once used for the fundamental material of which all living things were thought to be composed. It was studied by a number of early scientists, especially by Félix Dujardin, J. E. Pur...

crossing over

(Encyclopedia)crossing over, process in genetics by which the two chromosomes of a homologous pair exchange equal segments with each other. Crossing over occurs in the first division of meiosis. At that stage each ...

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