Linear driving force Subject

ATP synthesis can also be induced in isolated thylakoids by subjecting them to a brief electric field pulse [12,47,48]. The driving force is presumably an induced transthylakoid electric potential of about 200 mV which is induced by field pulses of around 1000 V per cm. The amount of ATP synthesized is linear with the number of pulses, with no apparent lag, and with the duration of each pulse. Less than 1 molecule of ATP is synthesized per pulse per ATP synthase, but the rate of ATP synthesis compares favorably with the rate observed during light phosphorylation if one assumes that ATP is synthesized only during the pulse. 

Interface stability in co-extrusion has been the subject of extensive analysis. There is an elastic driving force for encapsulation caused by the second normal stress difference (56), but this is probably not an important mechanism in most coprocessing instabilities. Linear growth of interfacial disturbances followed by dramatic breaking wave patterns is observed experimentally. Interfacial instabilities in creeping multilayer flows have been studied for several simple constitutive equations (57-59). Instability modes can be traced to differences in viscosity and normal stresses across the interface, and relative layer thickness is important. 

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