Displacement, fractional

FIGURE 14 Purification of rHu-BDNF from its variants by displacement chromatography. (Barnthouse et a/.39) (A) Analytical chromatography of feed stock by high temperature reversed-phase acetonitrile gradient. Column 4.6 X 250 mm Vydac C4 sample 50 jj.% injection of rHu-BNDF. (B) Displacement of rHu - BDNF by protamine. Column 4.6 X 500 mm, POROS HS / M loading 20 mg / mL column volume mobile phase 50 mM phosphate buffer, pH 7.0, 500 m/W NaCI displacer 2 mM protamine sulfate. (C) High-temperature reversed-phase assay of three displacement fractions. Overlay of fractions from the early (fraction 16), intermediate (fraction 18), and late (fraction 31) parts of the displacement train. 

Experimental work of Kalasz et al. resulted in the statement of the characteristics and basic rules of displacement chromatography. They conceived properties of the fully developed displacement train, factors affecting displacement development, efficacy of separation, analysis of displaced fractions, determination of displacement diagrams from Langmuirian isotherms, as well as selection of the column, carrier, and displacer for displacement chromatography. Concentration of the sample is a particular feature of displacement chromatography. However, the displacer in the carrier is also definitely concentrated through the development of the displacement train. 

Characterization of Displaced Protein. With labelled antithrombin III, chromatography of the displaced radioactivity on heparin-Sepharose revealed that the bulk of the displaced radioactive material did not bind to heparin-Sepharose (Table II). With arvinized plasma as the displacing eluent, 65% of the antithrombin III eluted in the void volume, compared with 49% of the control I-antithrombin III (diluted in citrated plasma) that had not previously been used to inactivate thrombin the latter unbound fraction was likely labelled impurities or inhibitor modified by radiolabelling to lose its heparin affinity. With 5% (w/v) albumin used as a displacing eluent, 78% of the I-antithrombin III came out in the void volume. This increase in material that did not bind to heparin after displacement from heparin-PVA was attributed to post-complex antithrombin III, a modification of the original inhibitor resulting from the inactivation of thrombin. Neither thrombin-antithrombin III complex nor free antithrombin III were detected in the 5% (w/v) albumin displaced fractions while there was a barely detectable amount of complex (6%) and free antithrombin III (4%) in the material displaced by arvinized plasma. With the control I-antithrombin III, 25% of the radioactivity was determined to be free antithrombin III and 2% as complex. The remainder (22-27%) was not recovered from the column. 

Figure 8 Dynamic loading and unloading of a zonal rotor. (A) Gradient loaded with rotor spinning at 2000 rpm, (B) sample injected at 2000 rpm, followed by injection of overlay, (C) particles separated with rotor at speed, and (D) contents unloaded by introducing dense solution at rotor edge, displacing fractions at center. (Courtesy of Beckman Coulter, Inc.)...

The macroscopic sweep efficiency s the fraction of the total reservoir which is swept by water (or by gas in the case of gas cap drive). This will depend upon the reservoir quality and continuity, and the rate at which the displacement takes place. At higher rates, displacement will take place even more preferentially in the high permeability layers, and the macroscopic displacement efficiency will be reduced. 

The microscopic displacement efficiency is the fraction of the oil which is recovered in the swept part of the reservoir. If the initial oil saturation is S i, then... 

A large fraction of the chemical reactions known are used to form heterocyclic compounds. Displacement reactions and cycloadditions are particularly important, and their rates are therefore of great practical interest. The same is true for the rates of reverse reactions — ring opening by displacements or retrocycloadditions. It was realized over the last 40 years that... 

Hindered Settling When particle concentration increases, particle settling velocities decrease oecause of hydrodynamic interaction between particles and the upward motion of displaced liquid. The suspension viscosity increases. Hindered setthng is normally encountered in sedimentation and transport of concentrated slurries. Below 0.1 percent volumetric particle concentration, there is less than a 1 percent reduction in settling velocity. Several expressions have been given to estimate the effect of particle volume fraction on settling velocity. Maude and Whitmore Br. J. Appl. Fhys., 9, 477—482 [1958]) give, for uniformly sized spheres,... 

Leaching is the removal of a soluble fraction, in the form of a solution, from an insoluble, permeable sohd phase with which it is associated. The separation usually involves selective dissolution, with or without diffusion, but in the extreme case of simple washing it consists merely of the displacement (with some mixing) of one interstitial liquid by another with which it is miscible. The soluble constituent may be solid or liquid and it may be incorporated within, chemically combined with, adsorbed upon, or held mechanically in the pore structure of the insoluble material. The insoluble sohd may be massive and porous more often it is particulate, and the particles may be openly porous, cellular with selectively permeable cell walls, or surface-activated. 

Figure 10.16 shows the calculated velocity contours as a fraction of the average velocity in the channel (average face velocity). In addition, velocities ob- rained from the line sink model are plotted. It can be seen that, compared to the line sink model, the calculated contours are displaced somewhat in the positive direction, with the greatest relative difference near the exhaust opening and with decreasing relative difference as the dimensionless distance v/VX increases. 

Clearance is normally expres.sed as a percent or fraction of cylinder displacement. It is given by ... 

The nonuniform displacement can occur in the injection of the polymer solution and in the injection of the solvent. The former will be manifested in early fractions. The latter will be seen in the broadening of the distribution in late fractions and in the prolonged time necessary to wash the column. 

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