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The van Deemter equation is a hyperbolic function that predicts that there is an optimum velocity at which there will be the minimum variance per unit column length and, thence, a maximum efficiency. The van Deemter equation was the result of the first application of rate theory to the chromatography elution process.
The Cambridge Handbook of Physics Formulas. Cambridge University Press. ISBN 978-0-521-57507-2. A. Halpern (1988). 3000 Solved Problems in Physics, Schaum Series. Mc Graw Hill. ISBN 978-0-07-025734-4. R.G. Lerner, G.L. Trigg (2005). Encyclopaedia of Physics (2nd ed.). VHC Publishers, Hans Warlimont, Springer. pp. 12– 13.
The equations governing the plasma moments are called the moment or fluid equations. Below the two most used moment equations are presented (in SI units). Deriving the moment equations from the Vlasov equation requires no assumptions about the distribution function.
A review by Berthod [19] studied the combined theories presented above and applied the Knox equation to independently determine the cause of the reduced efficiency. The Knox equation is commonly used in HPLC to describe the different contributions to overall band broadening of a solute. The Knox equation is expressed as: h = An^(1/3)+ B/n + Cn ...
A modern self-contained HPLC Schematic representation of an HPLC unit (1) solvent reservoirs, (2) solvent degasser, (3) gradient valve, (4) mixing vessel for delivery of the mobile phase, (5) high-pressure pump, (6) switching valve in "inject position", (6') switching valve in "load position", (7) sample injection loop, (8) pre-column (guard column), (9) analytical column, (10) detector (i.e ...
This is considered one of the simplest unsteady problems that has an exact solution for the Navier–Stokes equations. [ 1 ] [ 2 ] In turbulent flow, this is still named a Stokes boundary layer, but now one has to rely on experiments , numerical simulations or approximate methods in order to obtain useful information on the flow.
The equations were first developed in the 1940s by Ronald Gurney [2] and have been expanded on and added to significantly since that time. The original paper by Gurney analyzed the situation of an exploding shell or bomb, a mass of explosives surrounded by a solid shell.
The original Langevin equation [1] [2] describes Brownian motion, the apparently random movement of a particle in a fluid due to collisions with the molecules of the fluid, = + (). Here, v {\displaystyle \mathbf {v} } is the velocity of the particle, λ {\displaystyle \lambda } is its damping coefficient, and m {\displaystyle m} is its mass.