Exhausted slices

These may be either fresh or dried. The former are prepared for analysis by reducing them to a pulp by means of the machines used for the non-exhausted slices the latter are ground to a fine powder. As a rule only the sugar in these products is determined, but in some cases also the water. 

With dry slices, the half-normal weight is introduced with basic lead acetate into a 200 c.c. flask and the volume made up to 206 c.c. or 12 64 grams of substance are made up to 200 Mohr c.c. or 12 62 grams up to 200 true c.c. The polarisation in a 20 cm. tube, multiplied by 4, gives the percentage of sugar. 

—This is determined by drying at 105 110° as with beet ( )  

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In the initial stages of purification, sucrose is recovered in juice form by crushing cane stalks or by extraction of sliced sugarbeets (cossettes) with hot water. The resulting solutions are clarified with lime, then evaporated to thick syrups from which sugar is recovered by crystallization. The final syrup obtained after exhaustive crystallization of sucrose is known as molasses. Enhanced recovery of sucrose from beet molasses is accomplished by ion-exclusion chromatography, a process used in some sugar mills in the United States, Japan, Finland, and Austria. 

An exhaustive method for obtaining the juice from beets has been proposed, in which the roots are sliced and macerated without destroying the integrity of tho slices., The weak juice thus extracted is employed for macerating a fresh portion of slices, and so on until the extract is sufficiently strong for defecation and filtration. 

Optical microscopy is the method used most frequently to obtain thicknesses directly. A portion of monolith is mounted in epoxy and sliced to obtain a cross section. The contrast between washcoat and monolith is sufficient to permit thickness measurements to be made optically. A typical cross section of a washcoat on a ceramic auto exhaust monolith is shown in Fig. 7. 

To understand the release mechanism, cryomicrotomy was used to slice 10 m-thick sections throughout the matrices. Viewed under an optical microscope, polymer films cast without proteins appeared as nonporous sheets. Matrices cast with proteins and sectioned prior to release displayed areas of either polymer or protein. Matrices initially cast with proteins and released to exhaustion (e.g., greater than 5 months) appeared as porous films. Pores with diameters as large as 100 /xm, the size of the protein particles, were observed. The structures visualized were also confirmed by Nomarski (differential interference contrast microscopy). It appeared that although pure polymer films were impermeable to macromolecules (2), molecules incorporated in the matrix dissolved once water penetrated the matrix and were then able to diffuse to the surface through pores created as the particles of molecules dissolved. Scanning electron microscopy showed that the pores were interconnected (7). 

Figure 1 shows a family of 2-D slices (Re(n) varied and Im(n) fixed) of a typical error surface obtained from data acquired for a PEG particle. The three independent factors that define the scattering pattern - size, Re(n), and Im(n) - are systematically varied to find the best possible match to the experimental data by locating the minimum in a 4-dimensional error function. From exhaustive analysis of these error surfaces from many different sized particles, we find absolute size uncertainties to be between 2 and 5 nanometers, and the uncertainty in Re(n) to be between lO- and 5 x lO " For materials with a low molar absorptivity (typical of most dielectric liquids), Im(n) is correspondingly small - on the order of lO- to 10 At these values, there is very little (if any) effect on the match to data by varying Im(n). For many polymers (polyvinyl chlorides for example) however, this is not the case and Im(n) can be as large as 10 At this order of magnitude, Im(n) does indeed influence the Mie analysis ofthe data. 

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