Tandem arrangement

The upi-SO screen display ( Figure 7 ) shows the A-scan signal (top) and the resulting B-scan image (bottom) for the tandem arrangement of Figure 6. The flaw reflection is seen on the left. 

Cooling is most effectively accompHshed with a tandem arrangement of two extmders, as shown ia Figure 12, whereia the first extmder ensures complete dissolution of the blowiag ageat, and the second extmder is operated at slow speed for optimum cooling. Additional information on extmsion of foams is contaiaed ia Reference 28 (see FoAAffiD plastics Insulation, thermal). 

For example, if the application is actually 800 psi, you would pressurize the barrier tank support system and the area between the two seals at 400 psi. This way the inboard seal would seal 400 psi (800 - 400 = 400 psi) and the outboard seal would also seal 400 psi (400 - 0 = 400 psi). Each seal independently could seal maybe 500 psi, but not 800 psi. Together, the two seals in this tandem arrangement ean seal 800 psi and higher depending on the barrier tank pressure. 

Some purists hold baek from ealling this type seal a true double or dual seal . This is because if one seal in this tandem arrangement fails, the other will immediately fail too. 

Figure 9.13 The DNA-binding region of the protein Oct-1, the POU region (green), comprises two domains, the POU-specific domain (dark green) and the POU homeodomain (light green) joined by a linker region (blue). These two domains bind to DNA in a tandem arrangement.

Figure 5>S4. Cutaway of a tandem arrangement non-contacting dry gas seal. Courtesy of John Crane Internationa )...

Figure 8-15. Typical dry gas seal system schematic for a tandem arrangement dry...

For the tandem arrangement gas seal, a primary seal vent must be pro vided to vent the leakage across the process side seal. This vent ma> lie to flare or other suitable gas disposal point. The back pressure under nor mal conditions should be kept to a low value. A small amount of back pressure is recommended to keep a positive differential across the see ondaiy seal. Leakage measurement may be provided in the vent line to provide health monitoring of the primary seal. Unfortunately, the rotameter, which would be the obvious choice, should not be used because of its lack o reliability. If an orifice or needle valve is used to set the back pressure to the seal vent, pressure upstream of the restriction can be measured for a relative flow measurement. This type of reading does provide trend data that may be used to judge the seal s performance. 

Giddings pointed out (32) that separated compounds must remain resolved throughout the whole process. This situation is illustrated in Figure 1.5, where two secondary columns are coupled to a primary column, and each secondary column is fed a fraction of duration Ar from the eluent from the first column. The peak capacity of the coupled system then depends on the plate number of each individual separation and on At. The primary column eliminates sample components that would otherwise interfere with the resolution of the components of interest in the secondary columns. An efficient primary separation may be wasted, however, if At is greater than the average peak width produced by the primary column, because of the recombination of resolved peaks after transfer into a secondary column. As At increases, the system approaches that of a tandem arrangement, and the resolution gained in one column may be nullified by the elution order in a subsequent column. 

C. Diffusion Pump Design and Operation. The pumping speed of a two-stage mechanical pump generally drops very rapidly below 10 J torr. By contrast, Fig. 6.3 shows that a typical diffusion pump has good pumping speed below this pressure. Therefore, a tandem arrangement of a diffusion pump with a... 

In order for an instrument to carry out MS-MS, it must be able to do the three operations outlined above. As we have seen however, ion-trap systems capable of MS-MS and MS(n) do not use a tandem arrangement of mass analyzers at all, but rather use a single ion trap for all three operations simultaneously. As has already been stated, these ion-trap tandem mass spectrometer experiments are very sensitive and are now user friendly. The ion trap brings the capability for carrying out MS-MS experiments to the benchtop at relatively low cost. 

Higashi Y,Yoshioka H,Yamane M, et al. Complete nucleotide sequence of two steroid 21-hydroxylase genes tandemly arranged in human chromosome a pseudogene and a genuine gene. Proc Natl Acad Sci USA 83 2841-2845,1986. 

Fig. 16-5 Tandemly arranged replicons in eukaryotic DNA generate a chain of replication bubbles. O denotes an origin of replication.

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