| diffusion of innovation | The broad dissemination of new ideas, procedures, techniques, materials, and devices and the degree to which these are accepted and used. (12 Dec 1998) |
|---|---|
| diffusion potential | Potential arising from different rates of diffusion of ions at the interface of two dissimilar fluids, a junction potential. (18 Nov 1997) |
| diffusion respiration | Maintenance of oxygenation during apnea by intratracheal insufflation of oxygen at high flow rates. Synonym: apneic oxygenation. (05 Mar 2000) |
| diffusion shell | A small vessel made of a semipermeable membrane through which peptone, but not serum albumin, can pass; used in performing the Abderhalden test. (05 Mar 2000) |
| facilitated diffusion | <physiology> 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 their passage through the plasma membrane, acting as either shuttles or pores. See: symport, antiport, uniport. (18 Nov 1997) |
| fick's law of diffusion | The principle that a substance put into solution will tend to diffuse towards constant concentration throughout the solution. (09 Oct 1997) |
| Fick's laws of diffusion | The direction of movement of solutes by diffusion is always from a higher to a lower concentration and the diffusive flux JA of solute A across a plane at x is proportional to the concentration gradient of A at x; i.e., JA = -D(CA/x), the increase of concentration of solute A with time, CA/t, is directly proportional to the change in the concentration gradient, i.e., CA/t = D(fl2/x2). (05 Mar 2000) |
| lateral diffusion | Diffusion in two dimensions, usually referring to movement in the plane of the membrane, such as the motion of fluorescently labelled lipids or proteins measured by the technique of fluorescent recovery after photobleaching (FRAP). (18 Nov 1997) |
| least diffusion circle | In the configuration of rays emerging from a spherocylindrical lens system, the place where diverging rays of the lens first forming a line image are balanced by converging rays of the second lens. (05 Mar 2000) |
| agar-gel reaction | <immunology> The reaction between an antibody and an antigen during an immunology lab procedure where the two are allowed to diffuse toward each other through an agar-gel medium. Lines of precipitation form in the places on the gel where the two react with each other and shows where the reaction has occurred. (09 Oct 1997) |
| agarose gel electrophoresis | <procedure> A type of electrophoresis that uses a matrix of highly purified agar to separate large nucleotides in size. (06 May 1997) |
| aluminum hydroxide gel | A suspension containing Al2O3, mainly in the form of aluminum hydroxide, used as an antacid; a dried form, with the same use, is obtained by drying the product of interaction in aqueous solution of an aluminum salt with ammonium or sodium carbonate. (05 Mar 2000) |
| aluminum phosphate gel | An aqueous suspension of between 4.0 and 5.0% of aluminum phosphate; used as an antacid. (05 Mar 2000) |
| bag-gel implant | An implant composed of a silicone rubber bag containing a silicone gel; used in augmentation mammaplasty. (05 Mar 2000) |
| gel | Jelly like material formed by the coagulation of a colloidal liquid. Many gels have a fibrous matrix and fluid filled interstices: gels are viscoelastic rather than simply viscous and can resist some mechanical stress without deformation. Examples are the gels formed by large molecules such as collagen (and gelatin), agarose, acrylamide and starch. (18 Nov 1997) |