pores diffusion

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• Diffusion — This article is about the generic concept of the time dependent random process. For other uses, see Diffusion (disambiguation). Diffusion describes the spread of particles through random motion from regions of higher concentration to regions of… …   Wikipedia

• Gaseous diffusion — is a technology used to produce enriched uranium by forcing gaseous uranium hexafluoride, UF6, through semi permeable membranes. This produces a slight separation between the molecules containing uranium 235 and uranium 238. By use of a large… …   Wikipedia

• Knudsen diffusion — is a means of diffusion that occurs in a long pore with a narrow diameter (2–50nm) because molecules frequently collide with the pore wall. [cite web |url=http://www.mse.ufl.edu/ ssinn/Backgrounds/theo02 diff.html |title=Transport in Small Pores… …   Wikipedia

• facilitated diffusion — (= passive transport) A process by which substances are conveyed across cell membranes faster than would be possible by diffusion alone. This is generally achieved by proteins that provide a hydrophilic environment for polar molecules throughout… …   Dictionary of molecular biology

• MEMBRANES (transferts) — Si les propriétés des membranes sont connues depuis le début du XVIIIe siècle, leurs applications ne sont apparues, en laboratoire, que vers le milieu du XIXe siècle et, dans l’industrie, dans la seconde moitié du XXe siècle. Philippe de La Hire… …   Encyclopédie Universelle

• POUDRES (MÉTALLURGIE DES) — La métallurgie des poudres est aussi ancienne que l’art des potiers et des céramistes. Cependant, ce qui n’était que techniques ancestrales purement empiriques s’est transformé en une discipline scientifique dans les années 1930, dès qu’on a… …   Encyclopédie Universelle

• cell — cell1 cell like, adj. /sel/, n. 1. a small room, as in a convent or prison. 2. any of various small compartments or bounded areas forming part of a whole. 3. a small group acting as a unit within a larger organization: a local cell of the… …   Universalium

• Mass diffusivity — This article is about coefficient of molecular diffusion of mass. For other uses, see Diffusivity (disambiguation). Diffusivity or diffusion coefficient is a proportionality constant between the molar flux due to molecular diffusion and the… …   Wikipedia

• Sintering — is a method used to create objects from powders. It is based on atomic diffusion. Diffusion occurs in any material above absolute zero but it occurs much faster at higher temperatures. In most sintering processes the powdered material is held in… …   Wikipedia

• Porosity — or void fraction is a measure of the void (i.e., empty ) spaces in a material, and is a fraction of the volume of voids over the total volume, between 0–1, or as a percentage between 0–100%. The term is used in multiple fields including… …   Wikipedia

• Nuclear magnetic resonance in porous media — Nuclear magnetic resonance (NMR) in porous media covers the application of using NMR as a tool to study the structure of porous media and various processes occurring in them.[1] This technique allows the determination of characteristics such as… …   Wikipedia