Sigma centrifugal sedimentation

The so-caUed Sigma concept has been widely used in the field of centrifugal sedimentation ever since its first development by Ambler in 1952. It is a simplified relation between the machine performance in terms of X50, total volumetric flow rate Q and an index of the centrifuge size E. The cut size X50 is represented by its terminal settling velocity Vg in the given liquid under gravity so that from Stokes law (using equation 7.5b for the definition of K)... 

This approach to describing centrifuge performance has become known as the sigma theory . It provides a means for comparing the performance of sedimentation centrifuges and for scaling up from laboratory and pilot scale tests see Ambler (1952) and Trowbridge (1962). 

Step I Transfer washed eggs into 5 ml of solution A in a capped 15 ml centrifuge tube in a water bath for 1 h at 38°C. Shake vigorously for 10 min. Sediment by centrifugation and remove all but 0.5 ml of the supernatant fluid. Solution B. Artificial intestinal fluid (AIF) trypsin (Sigma, Type II 10000-13000 BAEE units/mg)... 

In order to determine the type of lipid binding the peptides w ere transferred to nitrocellulose membranes and were incubated before antibody incubation for 60 min with phospholipase A2 (Sigma, lipase concentration 1 mg/mg chlorophyll) or the PS 1 particles were incubated before SDS-PAGE for 60 min with phospholipase A2. Furthermore, the PS I particles were washed with acetone or methanol before SDS-PAGE in order to extract lipids that were only weakly bound by intemiolecular interaction. Therefore, PS I particles were incubated with methanol or acetone for 30 min at 4°C, centrifuged at 5.000 x g for 20 min and washed two limes with water. The sediments... 

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