1. The random movement of molecules or ions or small particles in solution or suspension under the influence of brownian (thermal) motion toward a uniform distribution throughout the available volume; the rate is relatively rapid among liquids and gases, but takes place very slowly among solids. 2. Light scattering.
- facilitated d. See facilitated transport.
- gel d. d. in a gel, as in the case of gel d. precipitin tests in which the immune reactants diffuse in agar. SEE ALSO: immunodiffusion.
- passive d. See facilitated transport.

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dif·fu·sion dif-'yü-zhən n
1) the process whereby particles of liquids, gases, or solids intermingle as the result of their spontaneous movement caused by thermal agitation and in dissolved substances move from a region of higher to one of lower concentration
2 a) reflection of light by a rough reflecting surface
b) transmission of light through a translucent material
dif·fu·sion·al -'yüzh-nəl, -ən-əl adj

* * *

dif·fu·sion (dĭ-fuґzhən) 1. the process of becoming diffused, or widely spread. 2. the spontaneous movement of molecules or other particles in solution, owing to their random thermal motion, to reach a uniform concentration throughout the solvent, a process requiring no addition of energy to the system. 3. the movement of solutes down concentration gradients across a semipermeable membrane such as a hemodialyzer membrane; the movement is generally of urea and low molecular weight toxins from the blood to the dialysate and of bicarbonate and acetate from the dialysate to the blood. 4. immunodiffusion.

Medical dictionary. 2011.

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  • Diffusion — Dif*fu sion, n. [L. diffusio: cf. F. diffusion.] 1. The act of diffusing, or the state of being diffused; a spreading; extension; dissemination; circulation; dispersion. [1913 Webster] A diffusion of knowledge which has undermined superstition.… …   The Collaborative International Dictionary of English

  • Diffusion [1] — Diffusion. In Gasen und Lösungen gleichen sich lokale Unterschiede der Konzentration allmählich durch Wanderung der Materie aus. Diesen Vorgang bezeichnet man im ersten Falle als Gas (Atmolyse nach Graham), im zweiten als Hydrodiffusion. Unter… …   Lexikon der gesamten Technik

  • diffusion — DIFFUSION. s. f. Terme de Physique. Il se dit Des fluides en parlant De l action de se répandre, ou de l état de ce qui est répandu. Diffusion de lumière, de la lumière. Il se dit figurément Da discours, du style, lorsqu il est trop abondant en… …   Dictionnaire de l'Académie Française 1798

  • diffusion — diffusion, diffusionism Diffusion refers to the spread of cultural attributes from one culture to another through contact between different cultural groups. Diffusion theory developed in the eighteenth and nineteenth centuries, in opposition to… …   Dictionary of sociology

  • Diffusion — Diffusion, 1) Weitläufigkeit; 2) Diffusion der Gase, die Eigenschaft der elastischen Flüssigkeiten, sich, den Gesetzen der Schwere entgegen, sowohl in anderen Gasen, als auch in Flüssigkeiten u. festen Körpern zu vertheilen, s.u. Gas …   Pierer's Universal-Lexikon

  • Diffusion — (lat., »Ergießung, Ausbreitung«), der Vorgang der allmählichen Mischung zweier miteinander in Berührung befindlicher Körper, insbes. von Flüssigkeiten oder Gasen. Gießt man Weingeist vorsichtig auf in einem Gefäß befindliches Wasser, so haben… …   Meyers Großes Konversations-Lexikon

  • diffusion — UK US /dɪˈfjuːʒən/ noun [U] ► MARKETING, COMMUNICATIONS the process by which information, ideas, changes in behaviour, etc. spread through a group of people: »The research looks at factors influencing the diffusion of innovative products in… …   Financial and business terms

  • Diffusion — Diffusion. См. Диффузия. (Источник: «Металлы и сплавы. Справочник.» Под редакцией Ю.П. Солнцева; НПО Профессионал , НПО Мир и семья ; Санкт Петербург, 2003 г.) …   Словарь металлургических терминов

  • Diffusion [2] — Diffusion des Lichts, s. Reflexion …   Lexikon der gesamten Technik

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