Density gradient centrifugation basics.

, Overview
The separation of a single sample part in the density gradient away from the heart is achieved by the subsidence or upper floating of the mixed sample through the density gradient layer. The density of the gradient fluid increases with the increase of centrifugation. Density gradients can be formed or self-forming during centrifugation, and often, density gradients can be divided into Rate-30nal estrifugation and isodycnic centrifugation.
A very thin layer of the mixture sample is laid over the upper part of the gradient fluid in the rate zone, and several "zones" containing the first left particle are formed at some point in the centrifugation process due to differences in the rate at which different groups of "particles" subside in the gradient fluid.
centrifugation process stops before the most drooping " sample (or the fastest-sinking sample) forms a sinking temple. Samples are collected with gradient fluid after centrifugation, and a purer part is obtained after the gradient material is removed by conventional techniques. The rate of subsidion of each single group depends on their shape, size, density, size of centrifugal forces, density of gradient fluids, and viscosity coefficients.
are often similar in shape for similar organisms. In the rate zone banding away from the mind we often make the maximum density of the gradient fluid not exceed the floating density of the sample in that gradient. Using the differences in the size of these biological components to form a different rate of settlement, select a specific moment, when the distance between the various pure sample zones in them pulls the farthest distance to stop centrifugation can achieve the purpose of separation.
the rate zone belt centrifugation method, iso-density centrifugation depends on the different densities of sample particles for centrifugal separation. Mixed samples can be spread over gradient fluid, placed under gradient fluid, or even mixed with gradient fluid.
the last method relies on centrifugal forces to form gradients (self-forming gradients) in the process of forming gradients, the purpose of separation purification is achieved by the single part of the sample to their own iso-density zone.
For rate zone band centrifugation, the maximum density of gradient fluid is generally less than the density of the various parts in the sample, that is, in the process of the sample subsiding is not in the formation of a sinking temple to separate the sample later, and in the iso-density centrifugal method, the initial maximum density of the gradient fluid often exceeds the density of each part of the sample, using each single group of parts to sink or float up to their respective iso-density zones to achieve the purpose of separation.
the theoretical basis of the density gradient centrifugation method is (Reference 1)
The sethering velocity of each pure sample part in the gradient fluid can be expressed as:
V- d2÷18× (σ
-s)÷η×-2r
V is the sedation velocity (cm/s) of a sample at a certain point in time
d: the diameter (cm) of the sample particles, and we hypothesise at the initial calculation that the sample particles are spheres. Non-spherical particle samples can be modified on the basis of the above.
σ: Density of sample particles (g/cm3)
s: density gradient fluid density (g/cm3)
η: viscous coefficient of density gradient fluid (g/cm/ s)
s:
centrifuges
reconds) rotational angle speed (1/s), s2 n÷60, N: rpm
: particles The distance
between the position and the axis of rotation, i.e. centrifugal radius (cm)
when the
σ>S V>0 is the sample sedation in the direction of centrifugal force

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