Derjaguin Approximation Scheme 2
Derjaguin may refer to: * Boris Derjaguin (1902–1994), Russian chemist ** Derjaguin approximation, expression of force profile interaction between finite size bodies ** DLVO theory, force between charged surfaces interacting through a liquid medium **DMT model of elastic contact; see Contact mechanics Contact mechanics is the study of the Deformation (mechanics), deformation of solids that touch each other at one or more points. A central distinction in contact mechanics is between Stress (mechanics), stresses acting perpendicular to the cont ...

Boris Derjaguin
Boris Vladimirovich Derjaguin (or Deryagin; ) (9 August 1902 in Moscow – 16 May 1994) was a Soviet and Russian chemist. He laid the foundation of the modern science of colloids and surfaces; an epoch in the development of the physical chemistry of colloids and surfaces is associated with his name. He was elected to the Russian Academy of Sciences, Derjaguin became famous in scientific circles for his work on the stability of colloids and thin films of liquids which is now known as the DLVO theory, after the initials of its authors: Derjaguin, Landau, Verwey, and Overbeek. It is universally included in text books on colloid chemistry and is still widely applied in modern studies of interparticle forces in colloids. In particular, the Derjaguin approximation is widely used in order to approximate the interaction between curved surfaces from a knowledge of the interaction for planar ones. Derjaguin was also briefly involved in polywater research during the 1960s and early 1970 ...
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Derjaguin Approximation
The Derjaguin approximation (or sometimes also referred to as the proximity approximation), named after the Russian scientist Boris Derjaguin, expresses the force profile acting between finite size bodies in terms of the force profile between two planar semi-infinite walls. This approximation is widely used to estimate forces between colloid, colloidal particles, as forces between two planar bodies are often much easier to calculate. The Derjaguin approximation expresses the force ''F''(''h'') between two bodies as a function of the surface separation as : F(h) = 2 \pi R_ W(h), where ''W''(''h'') is the interaction energy per unit area between the two planar walls and ''R''eff the effective radius. When the two bodies are two spheres of radii ''R''1 and ''R''2, respectively, the effective radius is given by : R_^ = R_1^+R_2^. Experimental force profiles between macroscopic bodies as measured with the surface forces apparatus, surface forces apparatus (SFA) or colloidal probe te ...
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DLVO Theory
In physical chemistry, the Derjaguin–Landau–Verwey–Overbeek (DLVO) theory explains the aggregation and kinetic stability of aqueous dispersions quantitatively and describes the force between charged surfaces interacting through a liquid medium. It combines the effects of the van der Waals attraction and the electrostatic repulsion due to the so-called double layer of counterions. The electrostatic part of the DLVO interaction is computed in the mean field approximation in the limit of low surface potentials - that is when the potential energy of an elementary charge on the surface is much smaller than the thermal energy scale, k_\text T. For two spheres of radius a each having a charge Z (expressed in units of the elementary charge) separated by a center-to-center distance r in a fluid of dielectric constant \epsilon_r containing a concentration n of monovalent ions, the electrostatic potential takes the form of a screened-Coulomb or Yukawa potential, \beta U(r) = Z^2 ...
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