This is an interesting and potentially important article, but to divulge a bit - "nano" is not required to exceed Carnot. Probably helps though.
In fact, almost 50 years ago, working for NASA on a project which was patented and then discontinued (go figure) . Eugene Laumann exceeded the Carnot limitation at the many kilowatt level - with a hydrogen powered diesel. It was possibly OU given the losses - but that claim was carefully avoided. The term "OU" was not even around then. This particular power supply was intended for space (in a closed cycle with photoelectric water splitting) - but NASA switched to AMTEC for weight reduction - and then ignored the ICE results for many years. After all, gasoline was below 50 cents a gallon so you cannot blame them. Several years ago Eugene Laumann, who was in his eighties and almost blind, provided copies of his papers and data, some of which are not online at DTIC. The grand hope is to renew that work someday, in the context of LENR. He did these experiments using ultra-high compression and an extremely lean fuel mix (all the fuel was H2 at well below the published flammability level). Laumann was yet another of many excellent but overlooked scientists who were way ahead of NASA in civilian relevance - decades ago, who did experiments that would be called "groundbreaking" today. "fonly" (as they say) the USA was not now a debtor nation, and also had the good sense to look though its own "cold case" files. BTW - for those who have followed the overlap of LENR and CQM - the "lattice" (substitute for a metal lattice) in this design, assuming that LENR may have been involved (which is not proved or even claimed) - was provided by mostly argon atoms squeezed to several hundred bar at TDC. where their effective density was similar to a metal lattice. A lattice of extremely high mobility, shall we say? From: Roarty, Francis X Yet another perspective for the same anomalous environment? <http://prl.aps.org/abstract/PRL/v112/i3/e030602> http://prl.aps.org/abstract/PRL/v112/i3/e030602 The researchers focus on an individual ion in a squeezed state unbalancing noise along 2 axis. Isn't this what nano geometry accomplishes at a system level for bulk gas in what we often refer to as our NAE?

