Centrifugation components

The dimensional continuation treatment suggests a further breakdown of contributions to the energy, since the transformations described above lead to a well-defined separation of the kinetic operator into differential and centrifugal components. The relative contributions of these pieces depend on the dimensionality. For example, for the hydrogen atom, we can express the kinetic operator as follows ... 

The factor / is also called reduced transition probabihty. As in the theory of P decay ( Sect. 2.4.2.2) the quantity Ti/2 /is a measure of the internal decay rate. In the derivation of the formula ( 2.64), it was assumed that the a particle is emitted with zero angular momentum (and therefore the centrifugal component shown in Fig. 2.35 is zero). 

This is so because T does not have the centrifugal component and the mass density p(r) is equal to 0 outside the earth. (This would be trae only if the earth s atmosphere did not exist as it does exist, it has to be dealt with. This is done in a corrective fashion, as we shall see below.) This homogeneous form of Poisson equation is known as Laplace equation. A function (T, in our case) that satisfies the Laplace equation in a region (outside the earth, in our case) is known as being harmonic in that region. 

Conditions for the Separation of Selected Cellular Components by Centrifugation... 

Figure 5.7 Eight components, with AT = 0 to 7 and separated by centrifugal distortion, of the 7 = 8 — 7 microwave transition of SiH3NCS...

Fig. 1. Distribution of component cells by density in a centrifuged sample of human blood.

Fig. 5. Separation in Latham bowl (a) whole blood is pumped down the feed tube and enters bowl at bottom (b) centrifugal force spins denser cellular components outside, leaving plasma or platelet-rich plasma (PRP) in inner band (c) when bowl is full, plasma flows out effluent tube, followed by platelets and then leukocytes, until bowl is almost completely full of ted cells (d) after draw is completed, bowl stops spinning and uncoUected components are...

Reverse Osmosis. Membranes are used for the separation of smaller components (<500 daltons). They have smaller pore space and are tighter than those used for ultrafiltration. High pressure pumps, usually of the positive piston or multistage centrifugal type, provide pressures up to 4.14 MPa (600 psi). 

Some slurry processes use continuous stirred tank reactors and relatively heavy solvents (57) these ate employed by such companies as Hoechst, Montedison, Mitsubishi, Dow, and Nissan. In the Hoechst process (Eig. 4), hexane is used as the diluent. Reactors usually operate at 80—90°C and a total pressure of 1—3 MPa (10—30 psi). The solvent, ethylene, catalyst components, and hydrogen are all continuously fed into the reactor. The residence time of catalyst particles in the reactor is two to three hours. The polymer slurry may be transferred into a smaller reactor for post-polymerization. In most cases, molecular weight of polymer is controlled by the addition of hydrogen to both reactors. After the slurry exits the second reactor, the total charge is separated by a centrifuge into a Hquid stream and soHd polymer. The solvent is then steam-stripped from wet polymer, purified, and returned to the main reactor the wet polymer is dried and pelletized. Variations of this process are widely used throughout the world. 

NonmetalHc centrifugal pumps utilize polymers for all components coming into contact with the pumping media. Even the steel (qv) shaft is sleeved with plastic to isolate the shaft from the fluid. Mechanical seals are reversed so that the metal face does not come into contact with the corrosive... 

The stress resulting from the axial forces must be considered in analy2ing the parts which resist axial separation, such as bolts, nuts, rings, etc. On scroU centrifuges the axial force owing to the axial component of the conveyor torque must also be considered. 

The electric motors are often the noisiest component of the centrifuge assembly. Most standard motors in the 75—250 kW range develop noise levels of 85 dbA (weighted sound pressure level using filter A, per the ANSI standard). A quiet motor can reduce this level by 5 dbA and should be used whenever noise is of concern. 

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