Seals, regional

For interactions between packaging and product the above descriptions of both material transport processes by diffusion and convection as well as the simultaneous chemical reactions come into consideration. The general transport equation (7-10) is the starting point for solutions of all specific cases occurring in practice. Material loss through poorly sealed regions in the package can be considered as convection currents and/or treated as diffusion in the gas phase. 

A potential sealing problem exists if (1) the vapor and liquid flow rates available for startup fall outside the area between the two curves, or (2) the area between the two curves is too narrow, and relatively small variations in flow rates during startup result in column operation outside the required sealing region. 

The sealed regions of the membrane are also included in the plot in Fig. 5.15. There, because of the fully developed flow (the radial velocity is zero, the axial velocity is constant), the pressure decreases linearly with the axial coordinate. 

Optical microscopy techniques can also be applied to packaging failure problems. Sections can be taken through a heat seal region to establish the integrity of the seal. Molecular orientation, melt flow, blend homogeneity, and crystallinity can be observed that can reveal the cause of stress cracking and other types of packaging failures. 

Nucleotide sequences were edited and forward and reverse sequences assembled with Sequencher 3.1 (Genes Code Corporation). The assembled sequences were aligned manually using Se-Al v 2.0 (http //evolve.zoo.ot.ac.uk/software.html id=seal). Regions of incomplete data and ambiguous alignment were identified and excluded from subsequent analyses. 

Figure 2.7 Cross-section of two solid electrolyte fuel cells of the bell-and-spigot type with shunt current paths in the seal region developed at Westinghouse (1963)...

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