Centrifugation basic principles

Although this introduction outlines the basic principles of centrifugation, it does not take into account other factors that influence the rate of particle sedimentation. Centrifuged particles migrate at a rate that depends on the mass, shape, and density of the particle and the density of the medium. The centrifugal force felt by the particle is defined by Equation 7.1. The term m is the effective mass of the particle, that is, the actual mass,... 

More recently, this method has been successfully extended by us18 to form the inverse systems, i.e. water core/polymer shell particles dispersed, initially in oil, but then transferred to an aqueous continuous phase. Clearly, whether one needs an oil or a water core depends on the nature of the active material to be released. Now one starts with a water/oil emulsion, rather than an oil/water emulsion, but the basic principles are very similar. A variety of shell polymer systems were prepared, including PMMA and poly(tetrahydrofuran) [PTHF]. The high vapor pressure liquid used in this case was in general, acetone. It turned out, however, that these water core systems are intrinsically more difficult to make than the equivalent oil core systems, because large amounts of acetone were required to dissolve the polymers initially in the water-acetone mixtures. An oil was then required which did not mix too well with acetone. In general, mineral oil worked reasonably well. In order to transfer the water core capsules into an aqueous continuous phase, the particles were centrifuged in... 

To reliably perform qualitative and quantitative analyses on body fluids and tissue, the clinical laboratorian must understand the basic principles and procedures that affect the analytical process and operation of the clinical laboratory. These include the knowledge of (1) the concept of solute and solvent, (2) units of measurement, (3) chemicals and reference materials, (4) basic techniques, such as volumetric sampling and dispensing, centrifugation, measurement of radioactivity, gravimetry, thermometry, buffer solution, and processing of solutions, and (5) safety. ... 

The basic principle is that the solid or semisolid sample is suspended into an aqueous solution and left under stirring to reach equilibrium of the analyte between the solid particles and water. In some methods, the solid phase is then removed by centrifugation, while in others, it is kept in the sample during the extraction. " ... 

This section addresses two basic principles of classification—sedimentation and field-flow fractionation—and the corresponding sizing techniques. Additionally, a chromatographic technique is briefly introduced. The focus lies on sedimentation or centrifugation analysis, which corresponds to its practical relevance for the characterisation of coUoidal suspensions. 

Cyclones designed for use with liquids are referred to as hydrocyclones, hydraulic cyclones or hydroclones. The basic principle employed to effect either concentration or classification of the solids is centrifugal sedimentation, caused by introducing the feed suspension tangentially into the unit they are particularly attractive for many applications because they have no moving parts. Specific aspects of design are provided by Svarovsky (1984). 

Hydrocyclones are used for solid-liquid separations as well as for solids classification, and liquid-liquid separation. It is a centrifugal device with a stationary wall, the centrifugal force being generated by the liquid motion. The operating principle is basically the same as that... 

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