Centrifuge-tube assembly

Figure 2 (right). Photograph of the centrifuge-tube assembly for measurements of solvent volume. 

In a second class of experiments, detailed studies of disappearance kinetics in sediment-water systems were performed. A series of centrifuge tubes was assembled containing identical concentrations of parent compound and identical sediment-to-water ratios. 

Almost every kind of holding or contacting equipment has been used as a chemical reactor at some time, from mixing nozzles and centrifugal pumps to the most elaborate towers and tube assemblies. This section is devoted to the general characteristics of the main kinds of reactors, and also provides a gallery of selected examples of working reactors. 

Step 3. Assemble the filtering apparatus with the filter. Pour the solution through the filter. Rinse the centrifuge tube twice with 5 mL of water and pour rinse water through filter. Record the time of separation of thorium from uranium. Wash and dry the precipitate with three 5-mL portions of ethanol. 

When crystallization is complete fit the matching glass rod (a close fit is essential) into the Craig tube and secure it tightly with a rubber band (Fig. 11,2b). Place the inverted assembly in a centrifuge tube and centrifuge for a few minutes (remember to use a counter-balancing tube and solvent). 

Components to contain the rotor tube assembly of a centrifuge enrichment machine... 

Now the fun part. You ve got to turn this thing upside down, put it in a centrifuge tube, and not have it come apart and spill everything. Easy to say— Solvent is now removed by inverting the Craig tube assembly into a centrifuge tube... (Mayo et al., p. 80). Easy to do. .. well ... 

Centrifuge the uncapped column/tube assemblies for 1 min at 3000 x g, then remove the spin columns and discard the flow-through. 

Sea Urchin. Ripe males (Marinus, Inc.) are blotted with paper towels to remove surface sea water, injected with 0.5 M KCl intracoelomically (--0.3 ml for L. pictus and 2 ml for S. purpuratus), and placed inside a 15°C incubator. Sperm are shed in a plastic container (weighing boat) and collected dry with a disposable transfer pipet into a 1.5-ml centrifuge tube placed on ice. Sperm can usually be stored as such however, if seawater dilutes the sample, sperm may be centrifuged for 15 sec at 1000 g in a microcentrifuge to concentrate them. Sperm can be stored without additives at 4°C for up to 5 days. We have observed low proportions of chromatin decondensation and incomplete nuclear envelope assembly with sperm stored for longer periods. 

Sperm nuclei are decondensed in 500 /il of an S o extract in a 1.5-ml centrifuge tube, and allowed to assemble a nuclear envelope in the presence of an ATP-generating system and GTP as described earlier. Nuclear swelling is promoted after 40 min as reported in Section VI,A. Swelling pronuclei are allowed to settle to the bottom of the tube for 1.5 hr. Nuclei free of membranes, or containing bound or fused membranes only, can be processed similarly. We let nuclei settle to the bottom of the tube, rather than centrifuge them, to minimize damage to the nuclear envelopes. 

Fig. 13 Separation of proteins and dipeptides by plain spiral tube and cross-pressed tube assemblies. Experimental conditions are as follows apparatus type-J coil planet centrifuge with 10 cm revolution radius separation column plain spiral tube assembly nine spiral layers about 40 m long, 1.6 mm I.D. FEP tube with a total capacity of 103 ml cross-pressed spiral tube assembly nine spiral layers about 40 m long, 1.6 mm I.D. FEP tubing cross-pressed at 1 cm interval with 95 ml capacity solvent system 12.5% (w/w) PEG-1000 and 12.5% (w/w) dibasic potassium phosphate in water (for protein separation) sample lysozyme and myoglobin, each 5 mg in 1 ml of upper phase (for protein seperation), trp-tyr (1.25 mg) and val-tyr (5 mg) in 0.5 ml of upper phase (for dipeptide separation) elution mode L-I-T flow rate 1 ml/ min (for protein separation), 2 ml/min (for dipeptide separation) detection 280 nm rpm 800.

Fig. 15 Protein separation by cross-pressed and radial groove-compressed spiral tube assembly at various revolution speeds and flow rates. Experimental conditions are as follows apparatus type-J coil planet centrifuge with a 10 cm revolution radius solvent system 12.5% (w/w) PEG-1000 and 12.5% (w/w) dibasic potassium phosphate in water sample lysozyme and myoglobin, each 5 mg in 1 ml of upper phase elution mode L-I-T detection 280 nm.

Step 7. Remove the solvent by inverting the Craig tube assembly into a centrifuge tube and spinning the mother liquors away from the crystals (Fig. 5.32). This operation should be carried out with care. First, fit the head with a thin copper wire (Fig. 5.32), held in place by a loop at the end of the wire that is placed around the narrow part of the neck. Some Teflon heads have a hole in the neck to anchor the wire. The copper wire should not be much longer than the centrifuge tube. 

Step 9. Place the assembly into a centrifuge tube, balance the centrifuge, and spin the mother liquors away from the crystals (Fig. 5.32). This... 

Place a clean 50 mL centrifuge tube on the product collection position. Remove the vessel assembly from the cavity, remove the luer ping, and immediately place the reaction vessel in to the vacnnm manifold. Transfer the cleaved peptide by vacuum filtration into the 50 mL centrifuge tube. Wash any residual peptide from the resin with a minimal amonnt of TFA (up to 1 mL). 

Assemble the reaction components (wTable 1) (reeNote 20). Gently mix by pipetting up and down. If necessary, centrifuge briefly to return the sample to the bottom of the tube. 

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