Sharpening front

Figure 8 Effect of reaction rate. Solid line computed for reaction rate constant K = 5yr, dotted line for K = 50 yr and dashed line for k = 0.5 yr L Note that front sharpens as reaction rate increases. See Figure 6 for calculation details.

Figure Bl.18.11. Confocal scanning microscope in reflection the pinliole in front of the detector is in a conjugate position to the illumination pinliole. This arrangement allows the object to be optically sectioned. The lens is used to focus the light beam onto the sample and onto the pinliole. Thus, the resulting point spread fimctioii is sharpened and the resolution increased.

Vorsatz-linse, /, lens placed in front, -papier, n. book lining paper, fiyleaf paper, vorschalten, v.t. (Elec.) introduce (into a circuit), cut in, connect, connect in series. Vorschaltwiderstand, m. (Eke.) (rheostatic) resistance, series resistance, vorschkrfen, v.t. sharpen (or strengthen) pre viously. 

More recently, there have been attempts to study band patterns as they are affected by shock layers in nonlinear chromatography.42 Shock layers are steep boundaries that develop when the boundary front of an elution band becomes very steep and self-sharpening at high concentrations. While comparison of predicted and experimental data was promising, this study, like the others mentioned above, was done with single-component samples and awaits further analysis with the kinds of multi-component feeds more frequently encountered in process purifications. 

Narahari, C.R., Strong, J.C., and Frey, D.D., Displacement chromatography of proteins using a self-sharpening pH front formed by adsorbed buffering species as the displacer, /. Chromatogr. A, 825, 115, 1998. 

Liquid-solid chromatography is representative of this theory because nonlinearity effects are usually appreciable. Mass transfer is fast and longitudinal diffusion effects may be ignored in describing the system. The net result is that the bands (zones) develop self-sharpening fronts and diffuse rear boundaries. It is because of this tailing that this technique is to be regarded... 

Figure 9.2), a step concentration increases as the column input produces a self-sharpening front, and in the case of a step decrease, a diffuse front will be formed (Figure 9.38b). 

This behavior is caused by the fact that the retention of the chemical decreases with increasing concentration in solution. In the case of the adsorption front, the retention decreases with increasing concentrations, and this effect leads to an instability and to the development of a narrow, self-sharpening front. In the case of the desorption front, the retention increases in time and leads to a broad, diffuse front (Biirgisser et al., 1993). 

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