| van Ermengen, Emile | <person> Belgian bacteriologist, 1851-1932. See: van Ermengen's stain. (05 Mar 2000) |
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| van Ermengen's stain | <technique> A method for staining flagella which utilises glacial acetic acid, osmic acid, tannic acid, silver nitrate, gallic acid, and potassium acetate. (05 Mar 2000) |
| van Gieson, Ira | <person> U.S. Histologist and bacteriologist, 1865-1913. See: van Gieson's stain. (05 Mar 2000) |
| van Gieson's stain | <technique> A mixture of acid fuchsin in saturated picric acid solution, used in collagen staining. (05 Mar 2000) |
| van Helmont, Jean | <person> Flemish physician and chemist, 1577-1644. See: van Helmont's mirror. (05 Mar 2000) |
| van Helmont's mirror | An obsolete term for central tendon of diaphragm. (05 Mar 2000) |
| van Horne, Johannes | <person> Dutch anatomist, 1621-1670. See: van Horne's canal. (05 Mar 2000) |
| van Horne's canal | <anatomy> The major efferent lymph duct into which lymph from most of the peripheral lymph nodes drains. Recirculating lymphocytes that have left the circulation in the lymph node return to the blood through the thoracic duct. (18 Nov 1997) |
| Van Slyke apparatus | An apparatus for determining the amounts of respiratory gases in the blood. (05 Mar 2000) |
| Van Slyke, Donald | <person> U.S. Biochemist, 1883-1971. See: slyke, Van Slyke apparatus, Van Slyke's formula. (05 Mar 2000) |
| Van Slyke's formula | The value obtained when the square root of the urine flow (when below 2 ml/min) is multiplied by the urine urea concentration and divided by the whole blood urea concentration; represents an old empirical adjustment for the effect of low urine flow on urea excretion; sometimes corrected for body size by dividing by some function of body weight or surface area. Later, plasma concentration was substituted for blood concentration in the calculation. The normal value is about 54 ml/min per 1.73 m2 in an adult person. Synonym: Van Slyke's formula. (05 Mar 2000) |
| van't Hoff, Jacobus | <person> Dutch chemist and Nobel laureate, 1852-1911. See: van't Hoff's equation, van't Hoff's law, van't Hoff's theory, Le Bel-van't Hoff rule. (05 Mar 2000) |
| van't Hoff's equation | Equation for osmotic pressure of dilute solutions. See: van't Hoff's law. For any reaction, d(ln Keq/d(1/T) equals -dH/R where Keq is the equilibrium constant, T the absolute temperature, R is the universal gas constant, and dH is the change in enthalpy; thus, plotting ln Keq vs. 1/T allows the determination of dH. (05 Mar 2000) |
| van't Hoff's law | In stereochemistry, all optically active substances have one or more multivalent atoms united to four different atoms or radicals so as to form in space an unsymmetrical arrangement, the osmotic pressure exerted by any substance in very dilute solution is the same that it would exert if present as gas in the same volume as that of the solution; or, at constant temperature, the osmotic pressure of dilute solutions is proportional to the concentration (number of molecules) of the dissolved substance; i.e., the osmotic pressure, π, in dilute solutions is π = RTσci, where R is the universal gas constant, T is the absolute temperature, and ci is the molar concentration of solute i, the rate of chemical reactions increases between two-and three-fold for each 10캜 rise in temperature. (05 Mar 2000) |
| van't Hoff's theory | That substances in dilute solution obey the gas laws. Compare: van't Hoff's law. (05 Mar 2000) |