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SynopsisThe fractions obtained from the partially hydrolyzed branched Streptococcus saliuarius levan were examined in solution. Sedimentation coefficients, So, intrinsic viscosities, [o], weight-average molecular weights, uw, and radii of gyration were obtained from sedimentation velocity, viscosity, and light-scattering measurements. Double logarithmic plots of [o] vs zW and So vs au each yielded two linear segments intersecting at Xw = lo5. Hydrodynamic data suggest that fractions of aw > lo5 behave as compact spheres, whereas for uw < lo5, the particles are best characterized as linear random coils. Calculations based on theories of random coils and spheres support the above observations.

The general hydrodynamic behavior at small clearance Reynolds numbers of two fluids of different density and viscosity occupying the finite annular space between a rotating and stationary disk is explored using a simplified version of the Navier-Stokes equations which retains only the centrifugal force portion of the inertia terms. A criterion for selecting the annular flow fields that are compatible with physical reservoirs is established and then used to determine the conditions under which two-fluid flows in the annulus might be expected for specific fluid combinations.

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