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23 Cards in this Set

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What 3 things are centrifuges used for?
-simulating gravity
-seperating two things with diff densities and one's a liquid
-removing moisture
What is the diff btn centrifugal and centripetal force?
Centrif pulls out
Centrip is pulling in
What 3 factors affect force?
mass
velocity (angular)
radius
What's the equation for force?
F = mrw'2
What is RCF?
relative centrifugal force
what is RCF for?
allows comparison of centrifuge force between different machines
What IS RCF?
The number of g's imposed on a mass by swinging it in a circle of radius r at a speed of w
What's the equation for RCF?
RCF = (1.12x10^-5)rN^2
What factors affect settling in a centrifuge, and what law tells us that?
Stoke's law
V = kr^2g(dp-dL)n
Ok, in plain english please...
What 6 factors affect settling?
-Velocity of particles
-Gravity
-Particle shape
-Particle density
-Particle size/radius
-Liquid density and viscosity
how does particle shape alter
settling?
Density?
size/radius?
the smoother, the faster.
the more dense, the faster.
the bigger, the faster.
why do RBCs settle below WBCs in the Hct?
RBCs are more streamlined and dense than WBCs and these factors simply carry more weight than size.
what are the components of the electric motor in a centrifuge?
Armature windings, field coils, carbon brushes, etc.
Potentiometer
Brake
What's better, a mechanical or electrical brake?
Electrical - prevents bumping, quicker, more gradual.
what are the 2 types of centrifuge heads?
-Fixed angle (conical)
-Horizontal (swinging
What type of centrif is the hct?
Fixed angle (conical)
What are advantages of the fixed angle?
-Gains higher speeds
-Less friction
-Particles travel less distance
-Better seperaton of supernat in shorter period of time.
What are the disadvantages of fixed angle?
Particles pack at an angle so you can't measure their surface.
What are the advantages of a Horizontal (swinging) centrif?

Disadvantages?
Allows exact measurement of sediment.

Partcls move entire tubelength, swinging tubes create air resistance.
what are 4 clinical applications of centrifuges?
1. Seperation of solids/liquids
2. Hematocrit
3. Special purposes
4. Centrifugal analyzer
what are special purposes?
-cell washing
-blood processing (during surgery)
What are Centrifugal analyzers defined as?
analytical instruments in clinical chemistry that use centrifugal force to transfer liquids and monitor several simultaneous chemical rxtns.
what is the advantage of centrifugal fast spectrophotometry?
it allows discrete analysis of each sample, seperated by an actual physical barrier at all times.