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2023-03-12T15:04:51Z

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In [[mechanosynthesis core]]s and [[Chemomechanical converter]] cores 
there is the need to provide sufficient counter-forces 
for advanced [[piezomechanochemistry]] to be possible. 

== Negative back-pressure ==

Note that required back-pressure can often be negative too. 
While VdW forces can support these too, stiffness may be lower. 
So it might be desirable to provide back-pressure from the sides such 
that compression and tension both face the same stiffness.

== Friction losses ==

'''Disclaimer:''' 
Note that minimizing friction losses is only sensible 
if losses in [[piezomechanochemistry]] can be made so small 
that they no longer massively dominate. This may or many not be possible. 
{{todo|Investigate how far efficiency in [[piezomechanochemistry]] can be driven. This was not done in [[Nanosystems]] beyond very very crude levels.}}

'''Options:''' 
To minimize friction losses from sliding over back-pressure panes 
there seem to be two options:
* reduce the contact area
* reduce contact time

=== Reduce contact area ===

As a crude first approximation: Half contact area gives half dynamic nanoscale friction. 
There are '''limits''' to this though. 
Fist '''stiffness falls''' potentially degrading efficiency in [[piezomechanochemistry]] 
potentially causing much bigger losses than gained by less contact area. 
Second for very small contact areas the '''atomic waviness may not average out well''' increasing losses again. 
See: [[Friction in gem-gum technology]]

=== Reduce contact time ===

The idea is to bring the back-pressure pane only in contact with the workpiece holding attachment chain when needed. 
So there is intermittent contact. If the attachment chain is not moving during contact then there is no sliding at all. 
Well, except in the mechanism that periodically establishes and removes contact. 
Also the chain needs to do periodic full stops. 
Or the backpressure-panes match speed with the chain and reciprocate. Complicated. 

Of peculiar concern may be that establishing and removing contact when done naively 
leads to energy turnover as VdW bonds are established and removed. 
Losses from this must be smaller than gains from the avoidance of sliding. 
Otherwise there's no point. 
One option for a less naive design may be '''[[VdW contactswap energyreplacement]]'''

== Related ==

* '''[[piezomechanochemistry]]'''
----
* [[piezomechanosynthesis]] (in [[mechanosynthesis core]]s)
* [[chemomechanical converter]]s
----
* [[Productive Nanosystems From molecules to superproducts]]

Piezomechanochemistry backpressure pane - Revision history

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