Disc centrifugation

The disc centrifuge, developed by Slater and Cohen and modified by Allen and Svarovsky [Allen and Svarovsky, Dechema Monogram,... 

The X-ray disc centrifuge is a centrifugal version of the gravitational instruments and extends the measuring technique well into the sub- Im-size range. 

Methods for making both forms solvent-soluble were the subject of many patents and closely guarded industrial secrets, but much of the mystery was cleared up in two papers by Gerstner [23] and Smith and Easton [24] published in 1966, by which time X-ray diffraction, electron microscopy and disc centrifuge particle sizing methods had been brought to bear on the problem. 

Another type of disc centrifuge has nozzles or orifices at the periphery where thickened solids are discharged continuously, and sometimes a fraction of this discharge is recycled to ensure that the nozzles are able to prevent breakthrough of the clarified supernatant liquid. Sometimes these nozzles are internally fitted to the bowl. Others are opened and closed electrically or hydrostatically from a build up of the sludge within the bowl. 

In some cases, microbial cell fragments may arise and can be particularly problematic. For example, the disc centrifuges often used to remove yeast after brewery fermentations are known to produce shearing forces that break off yeast cell wall fragments (Siebert et ah, 1987). Agitation of yeast by other means is also problematic (Lewis and Poerwantaro, 1991 Stoupis et ah, 2003). In beer, the resulting particles resist sedimentation and impair filtration. 

An ICI-Joyce Loebl Disc Centrifuge MK III, a photosedimento-meter, was used to measure the latex particle size distribution. The latex had a unimodal particle size distribution with a diameter of 1.05 micrometers (surface area average). The methods of separating latex particles by a centrifugal field and detecting the size distribution by a photocell may be found in the literature. 

Latex particle sizes and polydispersity were measured by use of an ICI Joyce Loebl disc centrifuge (JLDC) photosedimentometer (11,12). 

The main types of industrial centrifuges used for bioparticle separations are the tubular, the multi-chamber, and the disc centrifuges Figure 11.8). The disc centrifuge may have nozzles to allow continuous exit of the concentrated suspension. The nozzles allow operation in a continuous mode, with Rf > 0. Tubular and multi-chamber centrifuges operate with... 

Schematic drawing of centrifuges (A) tubular, (B) multi-chamber, (C) disc centrifuge.

The mixture was sonicated to eliminate aggregates. A polystyrene latex with a broad distribution was obtained from Kodak. This distribution had been characterized previously by electron microscopy, ultra centrifuge and Coulter counter. A monodlsperse, surfactant free, sulfated, polystyrene standard and a mixture of 10 such monodlsperse standards were purchased from Interfaclal Dynamics Corporation. A polyvinyl chloride latex with a broad distribution was donated by B. F. Goodrich. This sample had been characterized by Joyce Loebl disc centrifuge. These samples were diluted to 0.01% solids and sonicated to eliminate aggregates. 

An Improved Disc Centrifuge Photosedimentometer and Data System for Particle Size Distribution Analysis... 

An Improved disc centrifuge photosedimentometer (DCP) was developed for use in the determination of the particle size and size distribution of latices, pigments and other particulates. Separation is based on Stokes Law for the sedimentation of particles in a centrifugal force field and does not rely on the use of particle size calibrants or standards. The DCP Instrument provides accurate stable particle size analyses over a wide range of conditions while at the same time is rugged enough for heavy use in both a research and quality control environment. A stand-alone data collection, analysis and management system was developed both for routine quality control operation and for research use of the instrument. 

Holsworth, R. M. Provder, T. Stansbrey, J. J. "A Novel External Gradient Formation Method for Disc Centrifuge Photo-sedimentometry Particle Size Distribution Analysis" This Volume. 

The disc centrifuge used in this study has been described previously (4, 5). (A commercial verlson of the instrument is now available from Brookhaven Instruments Corporation, Ronkonkoma, NY, as the Brook-haven DCP-1000 Particle Size Analyzer.) The latexes used in this study are monodisperse Dow polystyrene latex standards covering a range of sizes and two commercial latexes designated as 2 and 4, both of which had a broader dispersity than the polystyrene latex standards. All of the latex sample preparations analyzed in the statistical study were prepared in a similar manner. All the fluids were held in a thermostatically controlled temperature bath at 25°C. The temperatures at the beginning and end of each run were recorded. 

Koehler, M. E., Zander, R. A., Gill, T.T., "An Improved Disc Centrifuge Photosedimentometer and Data System", This Volume. 

COLL AND OPPENHEIMER Improved Techniques in Disc Centrifugation... 

We note that FFF and disc centrifugation both achieve high resolution rankings in Table II. This comparable resolution has been predicted theoretically any field (such as a sedimentation field) applied directly to a sample will lead to approximately the same resolution as found in an FFF system using the same field, providing the displacement distances are comparable (10). While in theory, resolution in FFF can be amplified by the arbitrary length of the separation path (channel length), in practice the two approaches have comparable levels of resolution. 

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