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Percoll was previously used in assisted reproductive technology (ART) to select sperm from semen by density gradient centrifugation, for use in techniques such as in vitro fertilization or intrauterine insemination. However, in 1996, Pharmacia sent out a letter to laboratories stating that Percoll should be used for research purposes only, not ...
Historically a cesium chloride (CsCl) solution was often used, but more commonly used density gradients are sucrose or Percoll.This application requires a solution with high density and yet relatively low viscosity, and CsCl suits it because of its high solubility in water, high density owing to the large mass of Cs, as well as low viscosity and high stability of CsCl solutions.
Differences between differential and density gradient centrifugation [ edit ] The difference between differential and density gradient centrifugation techniques is that the latter method uses solutions of different densities (e.g. sucrose , Ficoll , Percoll ) or gels through which the sample passes.
An electrochemical gradient is a gradient of electrochemical potential, usually for an ion that can move across a membrane. The gradient consists of two parts: The chemical gradient, or difference in solute concentration across a membrane. The electrical gradient, or difference in charge across a membrane.
The Marangoni stress (/), i.e., gradient in the surface tension due gradient in the surfactant concentration (from high in the centre of the expanding patch, to zero far from the patch). The viscous shear stress is simply the viscosity times the gradient in shear velocity ∼ μ ( u / l ) {\displaystyle \sim \mu (u/l)} , for l {\displaystyle l ...
Conjugate gradient, assuming exact arithmetic, converges in at most n steps, where n is the size of the matrix of the system (here n = 2). In mathematics, the conjugate gradient method is an algorithm for the numerical solution of particular systems of linear equations, namely those whose matrix is positive-semidefinite.
In numerical mathematics, the gradient discretisation method (GDM) is a framework which contains classical and recent numerical schemes for diffusion problems of various kinds: linear or non-linear, steady-state or time-dependent. The schemes may be conforming or non-conforming, and may rely on very general polygonal or polyhedral meshes (or ...
A photo of a disassembled DGT device, showing piston and cap. The device in this picture has been fitted with activated carbon for assimilating gold and/or bisphenols.. The most commonly used DGT device is a plastic "piston-type" probe, and comprises a cylindrical polycarbonate base and a tight-fitting, circular cap with an opening (DGT window).