External gradient

At any instant, pressure is uniform throughout a bubble, while in the surrounding emulsion pressure increases with depth below the surfaee. Thus, there is a pressure gradient external to the bubble which causes gas to flow from the emulsion into the bottom of the bubble, and from the top of the bubble back into the emulsion. This flow is about three times the minimum fluidization velocity across the maximum horizontal cross section of the bubble. It provides a major mass transport mechanism between bubble and emulsion and henee contributes greatly to any reactions which take place in a fluid bed. The flow out through the top of the bubble is also sufficient to maintain a stable arch and prevent solids from dumping into the bubble from above. It is thus responsible for the fact that bubbles can exist in fluid beds, even though there is no surface tension as there is in gas-liquid systems. 

Now let us consider the possibility that there will be a significant temperature difference between the bulk fluid and the external surface of the catalyst pellet. Equation 12.5.6 indicates that the temperature and concentration gradients external to the particle are related as follows ... 

Single-cell eukaryotes Linear DNA Organelle DNA (RNA) As above Ca2+ gradients (external store)... 

BLS). This paper describes a novel and alternative method for performing DCP analyses and in particular a new procedure for the formation of the spin fluid density gradient external to the DCP disc. This new patented method ( 3), known as the External Gradient Method (EGM), will be compared to the BLS method of analysis. The quantitative precision of the results obtained with EGM and BLS will be compared by statistical analysis.In addition, qualitative advantages of the EGM over the BLS method will be given. 

Acceleration force = converted momentum change partial pressure gradient + external forces - thermal diffusion force + shearing force + intermolecular friction force... 

Thermal-gradient External thermal gradient Similar to electrohydrodynamic patterning. Submicrometer to micrometer Morphology depends on film thickness, gap between the plates, thermal gradient and temperature of the plates [82, 155-165]... 

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