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23 Cards in this Set
- Front
- Back
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What 3 things are centrifuges used for?
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-simulating gravity
-seperating two things with diff densities and one's a liquid -removing moisture |
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What is the diff btn centrifugal and centripetal force?
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Centrif pulls out
Centrip is pulling in |
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What 3 factors affect force?
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mass
velocity (angular) radius |
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What's the equation for force?
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F = mrw'2
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What is RCF?
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relative centrifugal force
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what is RCF for?
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allows comparison of centrifuge force between different machines
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What IS RCF?
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The number of g's imposed on a mass by swinging it in a circle of radius r at a speed of w
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What's the equation for RCF?
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RCF = (1.12x10^-5)rN^2
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What factors affect settling in a centrifuge, and what law tells us that?
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Stoke's law
V = kr^2g(dp-dL)n |
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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 |
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how does particle shape alter
settling? Density? size/radius? |
the smoother, the faster.
the more dense, the faster. the bigger, the faster. |
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why do RBCs settle below WBCs in the Hct?
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RBCs are more streamlined and dense than WBCs and these factors simply carry more weight than size.
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what are the components of the electric motor in a centrifuge?
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Armature windings, field coils, carbon brushes, etc.
Potentiometer Brake |
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What's better, a mechanical or electrical brake?
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Electrical - prevents bumping, quicker, more gradual.
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what are the 2 types of centrifuge heads?
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-Fixed angle (conical)
-Horizontal (swinging |
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What type of centrif is the hct?
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Fixed angle (conical)
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What are advantages of the fixed angle?
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-Gains higher speeds
-Less friction -Particles travel less distance -Better seperaton of supernat in shorter period of time. |
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What are the disadvantages of fixed angle?
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Particles pack at an angle so you can't measure their surface.
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What are the advantages of a Horizontal (swinging) centrif?
Disadvantages? |
Allows exact measurement of sediment.
Partcls move entire tubelength, swinging tubes create air resistance. |
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what are 4 clinical applications of centrifuges?
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1. Seperation of solids/liquids
2. Hematocrit 3. Special purposes 4. Centrifugal analyzer |
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what are special purposes?
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-cell washing
-blood processing (during surgery) |
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What are Centrifugal analyzers defined as?
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analytical instruments in clinical chemistry that use centrifugal force to transfer liquids and monitor several simultaneous chemical rxtns.
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what is the advantage of centrifugal fast spectrophotometry?
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it allows discrete analysis of each sample, seperated by an actual physical barrier at all times.
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