Insects defy aerodynamic laws

... So we should go with planes with flapping wings? (I don't think so :-) ). Helicopters come closest. They fly by beating the air into submission. leodp

OT: Spider silk amazes researchers again!

Spiders spin unique phononic material - July 25, 2016 Excerpt: Scientists at Rice University and in Europe and Singapore studied the microstructure of spider silk to see how it transmits phonons, quanta of sound that also have thermal properties. They suggested what they learned could be useful to create strong synthetic fibers with silk-like properties.,,, New discoveries about spider silk could inspire novel materials to manipulate sound and heat in the same way semiconducting circuits manipulate electrons, according to scientists at Rice University, in Europe and in Singapore. A paper in Nature Materials today looks at the microscopic structure of spider silk and reveals unique characteristics in the way it transmits phonons, quasiparticles of sound. The research shows for the first time that spider silk has a phonon band gap. That means it can block phonon waves in certain frequencies in the same way an electronic band gap - the basic property of semiconducting materials - allows some electrons to pass and stops others. The researchers wrote that their observation is the first discovery of a "hypersonic phononic band gap in a biological material." How the spider uses this property remains to be understood, but there are clear implications for materials, according to materials scientist and Rice Engineering Dean Edwin Thomas, who co-authored the paper. He suggested that the crystalline microstructure of spider silk might be replicated in other polymers. That could enable tunable, dynamic metamaterials like phonon waveguides and novel sound or thermal insulation, since heat propagates through solids via phonons.,,, "(Spider) silk has a lot of different, interesting microstructures, and our group found we could control the position of the band gap by changing the strain in the silk fiber," Thomas said. "There's a range of frequencies that are not allowed to propagate. If you broadcast sound at a particular frequency, it won't go into the material.",,, Though silk has been studied for thousands of years, it has only recently been analyzed for its acoustic properties.,,, "Right now, we don't know how to do any of this in other macromolecular fiber materials," Thomas said. "There's been a fair amount of investigation on synthetic polymers like nylon, but nobody's ever found a band gap." http://phys.org/news/2016-07-spiders-unique-phononic-material.html

bornagain77

Praise Darwin! Andre