Centrifuge technology.

centrifugation technique is a method of placing suspended fluid containing tiny particles in centrifugal rotors and separating tiny particles by difference in density or mass using centrifugal forces generated by the rotation of the roors around the shaft.
I. Basic Principles
1, sequendation in the gravity field
will contain particles of the suspension liquid to sit for a period of time, the particles in the liquid by gravity action, so that heavier particles sink separate from the liquid, that is, "gravity subside". The subsidion of particles in the medium is influenced by the buoyant force, medium resistance and diffusion of the medium.
2, relative centrifugal force
centrifugal technology is based on the behavior of small particles in the centrifugal force field established and developed.
centrifuge
roors are able to circle at a steady advernal velocity, resulting in a powerful radiation-out centrifugal force field that gives centrifugal acceleration to any object in it. Make it subject to an out-of-the-way centrifuge force. Centrifugal force field G produced by the centrifuge can be calculated by the following formula
G s 2r s - roor aching velocity r-rotation radius (the distance between the position of the mass mass and the center of rotation)
centrifugal force field is commonly used relative centrifugal force RCF (Relative Centrifugal Force, RCF). The size of the relative centrifugal force is expressed in a multiplied number equivalent to gravity gravity (gravity acceleration, g), i.e.:
RCF s 2r/g×g s (2 sn) 2r/602g×g s 1.119×10-10× 5×n2r×g
N-rot speed, rpm/min g-gravity acceleration, 980.6cm/s2
3, settering velocity
the sethering velocity refers to the distance at which the particles move along the radius in unit time under the action of a powerful centrifugal force.
particles (or large molecules) of the separated substance are subjected to direct centrifugal forces Fc along the radius as they rotate with the roors in the
centrifugal tube
. The mass of the particles of the separated substance, Fc.M. 2r, M.
its seiding speed v is v;v=6.092×10-4×D2 (ρ-ρm)n2r/ηm
. D-particle diameter, cm;ρ and ρm are the density of particles and media, g/cm3; ηm-media viscosity, per pa.s Pa.s
thus, the particle seidation speed is related to three factors:
a, particles themselves properties: the separation speed is directly related to particle diameter and density. Large particles sink faster than small particles at the same density, and large particles sink faster than smaller densities when they are the same size.
b, medium properties: the seition speed and the media viscosity, density inversely, medium viscosity, density is slow particle subsidon.
c, centrifugal conditions, particle sedation speed is directly related to centrifugal speed and rotation radius. If other conditions remain unchanged, the settlement velocity increases with the increase of r, and when the velocity zone is centrifuged, r's effect on the settlement velocity is not conducive to achieving a satisfactory separation effect, so the density and viscosity of the medium need to be increased accordingly along the radius direction to overcome the effect of r's increase.
4, sedation coefficient
sedation coefficient refers to the unit centrifugal force field, the rate of particle subsidon is represented by S: S s/s 2r
cells and the various components of the cell sedation coefficient is very different, we can use biological samples of the seoration coefficient difference using centrifugal technology to separate them from each other.
sedation coefficient range and centrifugal conditions
name sedation coefficient, S relative centrifugal force, g centrifugal speed, r/min
cells >107<200 <15 00
4×106-107 600-800 3000
mitochondrials 2×104-7×104 7000 7000
102-1.5×104 1×105 30000
DNA
102 2×105 4 RNA
4-50 4×105 60000
Protein 2-25 >4×105 >60,000
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