External flow separated region

This may be understood by regarding the total flow field. In the region between the two particles, the external flow field is screened considerably (i.e. the velocities are smaller than in the far field) and the local shear rates are lowered accordingly (cf. Fig. 4.14). As a result, the momentum flux from the fluid phase to the particles is not as high as for two completely separated particles. 

Other Column Features. External Zone Broadening. If attention is not paid to the extracolumn volumes in connecting tubes, injection devices, and detectors, the efficiency of a separation may be decreased by zone broadening in these regions. This is especially important for the small and microbore columns just described when they are used at low flow rates. 

Constrained Search and the related approach of SCAMPI both integrate the conformational analysis closely with the pharmacophore discovery. This has the advantage that the sampling of conformational space can be more focused on key regions. With both Catalyst and DANTE, conformational analysis was explicitly kept separate, in the latter to allow one to take advantage of any innovations in conformational analysis tools. And, indeed, there continues to be a steady flow of new approaches in conformational analysis—pharmacophore discovery is critically dependent on high-quality exhaustive conformational analysis. Based on our experience thus far, we cannot conclude that either approach is superior (integrated vs. external). Furthermore, a consensus has not yet been reached on the optimal manner to perform conformational search as needed by pharmacophore discovery. This will continue to be a fruitful area of research. 

We have seen that in an oxidation electrons are released and that in a reduction they are acquired. In a battery, the release and acquisition are spatially separated. Electrons are released into an electrode, a metallic contact, in one region of the battery, travel through an external circuit, and then attach to the species undergoing reduction at a second electrode elsewhere in the battery. Thus, the redox reaction, the joint oxidation and reduction reactions, proceed, and in doing so, the flow of electrons from one electrode to the other is used to drive whatever electrical equipment is attached to the device. Modern batteries use a range of... 

FEE is an alternative separation technique to SEC that crosses the borders from soluble region into particle region. The separation takes place in a thin channel between two parallel plates where the sample flows in the axial direction. The flow profile in the channel is parabolic with the maximum velocity in the middle. External field (e.g., flow, thermal) applied in the perpendicular direction forces molecules to different distances from the channel wall, i.e., to different velocity layers. Thus, the elution time increases with decreasing distance of particles from the channel wall. 

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