Centrifugation medium

After incubation for the desired time interval, remove medium with test agent and incubate cells with fresh medium containing 40 xg ml NR dye. (An aqueous stock solution of 4 mg mH, shielded from light by foil, can be kept for several weeks.) This medium should be prepared earlier and incubated at 37°C overnight to allow for precipitation of small dye crystals. Centrifuge medium for 10 min at 1500 g before use and add 0.2 ml of decanted super-nate to each well. The first two wells on each plate should receive medium without NR and serve as blanks for spectrophotometric analysis. 

Purdenz. [Accurate Chem. Scientific] Iodine composition for laboratory use as a centrifugation medium. 

The Svedberg unit (S) is a sedimentation coefficient, which is a measure of the velocity with which a particle moves in a centrifugal field. It represents a hydrodynamic property of a particle, a property that depends on, among other factors, the size and shape of the particle. When two particles come together, the sedimentation coefficient of the resulting particle should be less than the sum of the individual coefficients because there is no frictional resistance between the contact surfaces of the particles and the centrifugal medium. 

Use in biological research culture media, centrifuging medium. 

The final and less commonly dealt-with member of the family of electrokinetic phenomena is the sedimentation potential. If charged particles are caused to move relative to the medium as a result, say, of a gravitational or centrifugal field, there again will be an induced potential E. The formula relating to f and other parameters is [72, 77]... 

In a suspension polymerisation monomer is suspended in water as 0.1—5-mm droplets, stabilised by protective coUoids or suspending agents. Polymerisation is initiated by a monomer-soluble initiator and takes place within the monomer droplets. The water serves as both the dispersion medium and a heat-transfer agent. Particle sise is controlled primarily by the rate of agitation and the concentration and type of suspending aids. The polymer is obtained as small beads about 0.1—5 mm in diameter, which are isolated by filtration or centrifugation. 

Aqueous media, such as emulsion, suspension, and dispersion polymerization, are by far the most widely used in the acryUc fiber industry. Water acts as a convenient heat-transfer and cooling medium and the polymer is easily recovered by filtration or centrifugation. Fiber producers that use aqueous solutions of thiocyanate or zinc chloride as the solvent for the polymer have an additional benefit. In such cases the reaction medium can be converted directiy to dope to save the costs of polymer recovery. Aqueous emulsions are less common. This type of process is used primarily for modacryUc compositions, such as Dynel. Even in such processes the emulsifier is used at very low levels, giving a polymerization medium with characteristics of both a suspension and a tme emulsion. 

Industrial separations are conducted in gravity or bath separators for a coarse feed, and in centrifugal separators for a fine feed (2,6,10). In gravity-type separators the feed and medium are introduced to the surface of a large quiescent pool of the medium. The float material overflows or is scraped from the pool surface. The heavy particles sink to the bottom of the separator and are removed using a pump or compressed air. The dmm separator (Fig. 13), up to 4.6 m dia and 7 m long, processes approximately 800 t/h, and treats feed of size up to 30 cm dia, operates in the gravity or the... 

Sedimentation (qv) techniques, whether based on gravitational forces or centrifugation, derive the particle size from the measured travel rates of particles in a Hquid. Before the particle analysis is carried out, the sample is usually dispersed in a medium to break down granules, agglomerates, and aggregates. The dispersion process might involve a simple stirring of the powder into a Hquid, but the use of an ultrasonic dispersion is preferred. 

Herein centrifugal separation in a Hquid medium is discussed. A brief presentation of centrifugal separation in a gaseous medium is also offered. 

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