Search results
Results from the WOW.Com Content Network
If the transport of nitrogen into the vascular compartment by perfusion exceeds removal of helium by perfusion, while transfer of helium into the vascular compartment by diffusion from the perilymph and endolymph exceeds the counterdiffusion of nitrogen, this may result in a temporary increase in total gas tension, as the input of nitrogen ...
It was first conceptualized by August Krogh in 1919 with the help of Agner Krarup Erlang to describe oxygen supply in living tissues from human blood vessels. [1] [2] Its applicability has been extended to various academic fields, and has been successful explaining drug diffusion, water transport, and ice formation in tissues. [3]
The term also refers to the removal of molecular oxygen (O 2) from gases and solvents, a step in air-free technique and gas purifiers. As applied to organic compounds, deoxygenation is a component of fuels production as well a type of reaction employed in organic synthesis , e.g. of pharmaceuticals .
The self-diffusion coefficient of neat water is: 2.299·10 −9 m 2 ·s −1 at 25 °C and 1.261·10 −9 m 2 ·s −1 at 4 °C. [2] Chemical diffusion occurs in a presence of concentration (or chemical potential) gradient and it results in net transport of mass. This is the process described by the diffusion equation.
The effect is also noted in the choroid rete, the network of blood vessels which carries oxygen to the retina. [3] In the absence of the Root effect, retia will result in the diffusion of some oxygen directly from the arterial blood to the venous blood, making such systems less effective for the concentration of oxygen. [ 4 ]
Gas exchange is the physical process by which gases move passively by diffusion across a surface. For example, this surface might be the air/water interface of a water body, the surface of a gas bubble in a liquid, a gas-permeable membrane, or a biological membrane that forms the boundary between an organism and its extracellular environment.
During this process the oxygen isotopes are fractionated: the clouds become enriched with 16 O, and the seawater becomes enriched in 18 O. Whereas equilibrium fractionation makes the vapor about 10 per mil (1%) depleted in 18 O relative to the liquid water, kinetic fractionation enhances this fractionation and often makes vapor that is about 15 ...
The large size of many arthropods in the Carboniferous period, when the oxygen concentration in the atmosphere reached 35%, has been attributed to the limiting role of diffusion in these organisms' metabolism. [14] But J.B.S. Haldane's essay [15] points out that it would only apply to insects.