Titanium-nickel (TiNi) shape memory alloys (SMAs) are used in the form of coil springs in most products because the coil springs generate a large stroke and a high recovery force.
Similarly to piston in a car engine, a heart is described by PV loops, where a heart of a healthy person is capable of closing a PV loop with large surface, i.e. it is capable of generating a large stroke volume (SV); versus a failing heart that is capable of generating much smaller SV (Figure 1).
The phi29 gp16 ATPase uses a revolution mechanism of the entropy-DNA affinity switch between the subunits to generate a power stroke that pushes dsDNA inward without rotation of DNA and the pump.
Different mechanisms can be envisaged (Fig. 4B): the Rea1 ATPase ring might be fixed on the pre-60S particle and a conformational change inside the ATPase domains may generate a power stroke that moves the Rea1 tail.
The gp16 ATPase and FtsK use a novel revolution mechanism, generating a power stroke between subunits through an entropy-DNA affinity switch and pushing dsDNA inward without rotation of DNA and the motor, whereas RuvB seems to employ a rotation mechanism that remains to be further characterized.
How RuvB rotates dsDNA still remains elusive, but a mechanochemical-coupling mechanism was proposed that two subunits of RuvB hexameric rings bind dsDNA and hydrolyze ATP to generate a power stroke and rotate DNA in a DNA binding-ATP hydrolysis step that relays along the ring [ 94].
Each key stroke generates a sequence of coded electrical pulses, which are then routed by electronic switching through an appropriate transmission system to the destination.
Using an experimental model to generate a wide range of stroke volumes for a constant tidal volume, we were able to investigate the dynamic relation between ZV and ZQ.
Strikingly, high- and low-affinity subunits are spatially segregated within two contiguous hemispheres in the ring, generating an asymmetric power stroke that drives the folding cycle.
Or was it a stroke of genius – generating a huge buzz, clearing the creative slate, and thrilling the fans?
Future microrobotic applications require actuators that can generate a high actuation force and stroke in a limited volume.
