Schlieren pattern

The gradual increase in the formamlde fraction to solution increased the elapsed time before schlieren patterns appeared. For the solution composition formamlde/acetone (40/60), slow convection flow appeared suddenly after 650 seconds, but the formation of the pellicle at the nascent membrane Interface could be clearly seen 15 seconds after submersion in the water bath. Such pellicles could not be discerned for solutions cast from THF or pure acetone. 

The schlieren experiments employing solutions with THF and dloxane as solvents proved that at least two different coagulation mechanisms exist in an unstirred bath. It is evident that Case B applied for the THF solution, while Case A applied for the dloxane solution. The depletion and removal of the THF from the cast layer Interface via convection flow (rather than diffusive exchange with water molecules) is instantaneous, and the rapid accumulation of the solvent on the surface of the aqueous coagulation bath is notable. As for the dloxane solution (Figure 7), schlieren patterns could not be observed even after 1000 seconds - even when phase... 

Figure 7. Coagulation of polysulfone (15 wt % in dioxane). Schlieren patterns were not detected. (This was the case for any coagulation of a polymer solution with a high specific gravity solvent.) Elapsed time = 45 s.

Meticulous observation of this mixing process (the slow disappearance of the Schlieren patterns as result of the disappearance of density differences), reveals that macromixing is quickly accomplished compared to the micromixing. This time-consuming process already takes place in... 

Ultracentrifugal analysis of Con A in solution revealed two components, the relative proportions of which depended on the experimental conditions. In Figure 6 (A), the Schlieren pattern of Con A at a concentration of 5 mg/ml in PBS at 5°C shows these two components. An s.. value of 5.52 S was obtained for the fast component and 4.15 S for the slower component. By comparing the relative areas under the peaks it was found that at this temperature 66% of the Con A molecules sedimented as the faster 5.52 S species. Higher temperatures favoured this species (Table II),... 

Figure 6. Schlieren patterns of Con A (5 mg/ml) in PBS, pH 7.4 (A) 4°C (B) 20°C. Movement is from left to right, speed 60,000 rpm, phase plate angle of 50°.

Check to see that the solution is flowing between the two sides of the gradient maker. Do this by looking for the schlieren patterns that exist at the entry of the formic acid into the water. 

Figure 6 represent various Schlieren patterns of the samples of different compositions. The Schlieren peak appears upward if the re-... 

Figure 6. Ultracentrifuge Schlieren patterns of the microemulsions along the line AB in Figure 1. Note the left hand side is the meniscus, and the right hand side corresponds to the bottom of the cell.

Figure 6. Model E analytical schlieren patterns of purified LPS. Equilibrium attained at 36,000 rpm at 25°C for 18 hours in 2°C sector cells. A 34% CsCl pattern of B. abortus LPS, sample from preparation run in Figure 5A. B 34% CsCl pattern of B. abortus LPS. C 39% CsCl pattern of P. multocida LPS.

Note first row concentration of components second row schlieren pattern. 

Fig. 5 (87). Sedimentation velocity Schlieren patterns of Cuprein isolated from bovine liver (hepatocuprein). Protein concentration was 7 mg/ml in 100 inM potassium phosphate buffer, pH 7.3. Photographs were taken at 16-min intervals after reaching 60000 rpm. Sedimentation from left to right...

Mixing conditions. In a flow analyser comprising a mixing chamber e.g., for analyte separation, a Schlieren pattern is observed inside the chamber inner volume under poor mixing conditions. This effect alters the recorded peak profile, which becomes noisy and less reproducible. 

The schlieren patterns displayed in the viewing screen and the photographic plates represent the refractive index gradient distribution across the optical cell (see Figure 1). The height of the schlieren line from the base line, H, is related to the refractive index gradient dn/dr by the following expression (13) ... 

Four principal patterns of convection were distinguished when pure liquids were employed cells, streamers, ribs, and vermiculated rolls. These names were chosen in an attempt to describe the actual appearance of the convection patterns and in accordance with historical designations. Examples are shown in Fig. 21. The patterns depicted there were exhibited in all of the liquids under various conditions. In particular, cells appeared to be the dominant patterns in all liquids for depths of 2 mm or less, and the cell size for the various liquids at the 1-mm and 2-mm depths is shown in Table VI. For a thin (< 2 mm) layer of given liquid evaporating into still air, the cell size increased with the depth of the liquid layer, and the flow which the cellular schlieren pattern represented was the same as that observed by Benard (see Fig. 3). These cells were quite immobile and generally neither grew nor decayed in size with time. A direct stream of dry nitrogen onto the surface of the liquid sharpened the cell peripheries and tended to reduce the cell size. 

Fig. 2. A stylized tracing of a low-density schlieren pattern showing the subdivision into 29 standard intervals, together with the corresponding (uncorrected) integral curve. The superimposed scale demonstrates the approximate magnitude of the F versus C effect for a typical lipoprotein analysis.

Fig. 4a and b. A normal male low-density pattern (film 393) reconstructed from computer-calculated concentrations in the cell for 29 standard intervals at each stage of the program calculations curve 1 represents unoorrected concentrations (corresponding to the tracing of the original schlieren pattern) curve 2 shows the rephasing due to the F versus C correction curves 3 and 4, respectively, demonstrate the additional effects of the correction to standard conditions of temperature and density and the correction for the Johnston-Ogston effect. 

An additional need for improvement in oiu method, especially for a large-scale application, seems to be a more efficient reading proeedure. This might best be attained by using a small inexpensive computer equipped with an optical scanning device. This would not only minimize individual variation and random error in the reading of films, but could potentially provide more accurate and extensive data about the original schlieren pattern than we are able to obtain from om current manual measurements. 

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