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Dirac cones, a band-structure of two cones touching each other, are the key to understand graphene exceptional properties. They also appear in the theory of photon waveguides and atoms in optical lattices. In here, the study of a Dirac cone deformation in an open system (a system that is perturbed by external agents) lead to the deformation of the Dirac cone, meaning a change in the fundamental properties of the system. This change is such that strange phenomena such as unidirectional transmission or reflection or lasers with single mode (really single) operation can be achieved. Proved experimentally in photonic crystals. New way for extremely pure lasers?

The problem is that the light cone angle has a limit - all particles with high momentum (mass x velocity) generate light cones with the same angle. Hence, these particles are indistinguishable. Now Chalmers researcher Philippe Tassin and his colleagues at the Free University of Brussels have designed a material that manipulates the Cherenkov cone so that also particles with high momentum get a distinct light cone angle too. The work is on the cover of this week's issue of the journal Physical Review Letters ("Controlling Cherenkov Radiation with Transformation-Optical Metamaterials").

This is about biological and technical hygromorphs, i.e. structures that change shape according to humidity. Next to pine cones, there is also a cool study on wheat awns which drill themselves into the soil just by daily variance of air humidity. Biomimetics would be passively controlled acutators or humidity driven valves in space station to open/close dehumidification devices.

Interesting, but only an abstract... do you have the full paper ?

Not yet. There is also some other nice mechanism of wheat awns and how they use changes in humidity to anchor in soil. Would maybe fit with the above mentioned work of oisin.

"V3Solar has developed a cone-shaped solar energy harvester that is claimed to generate over 20 times more electricity than a flat panel thanks to a combination of concentrating lenses, dynamic spin, conical shape, and advanced electronics."

Hmm.. that seems counter intuitive... how would it ever be that much better than a flat panel? Rotating the PV will only make sure only parts are illuminated. Operating temperature is a better argument, but that comes at the cost of exposure. Came across this little gem of a webpage, maybe we should outsource our impossibility EM drive work next time? :) https://www.metabunk.org/debunked-v3solars-spinning-solar-panel-cone-spin-cell-coolspin.t1166/

and all this without magic metamaterials ...

It's funny to see how people get more and more humble in the desperate attempt to save their stupid ideas... At the beginning was the brave and bold aim to cloak something in free space (in a sphere or a cylinder). This requires inhomogeneous, anisotropic, magnetic materials; hopeless!! So one reduces to one polarization, now we have inhomogenous, anisotropic materials; still hopeless! At this point one downgraded the pretension: instead of cloaking in free space, we make a "carpet cloak" and hide an object behind an invisible dent in a mirror. But if that shall be continuous, we still need inhomogeneity and this is very hard. So now instead of a dent we take a cone and then it is claimed to work ... for ONE polarization. But of course the cloak can't work at all incident angles... irony of fate: everything is now made from birefringent media, the antithesis of what the metamaterials dogma was at the beginning!

Hi Luzi, can you please send me the paper. We are writing a project based on sulfates and carbonates, and all this BS sounds great for the introduction (The authors used Calcite as birefringent material)

To our knowledge this is the first demonstration of in vivo optical imaging of the fast physiological processes that accompany phototransduction in individual photoreceptors.

Prince Rupert's drops (PRDs), also known as Batavian tears, have been in existence since the early 17th century. They are made of a silicate glass of a high thermal expansion coefficient and have the shape of a tadpole. Typically, the diameter of the head of a PRD is in the range of 5-15 mm and that of the tail is 0.5 to 3.0 mm. PRDs have exceptional strength properties: the head of a PRD can withstand impact with a small hammer, or compression between tungsten carbide platens to high loads of ∼15 000 N, but the tail can be broken with just finger pressure leading to catastrophic disintegration of the PRD. We show here that the high strength of a PRD comes from large surface compressive stresses in the range of 400-700 MPa, determined using techniques of integrated photoelasticity. The surface compressive stresses can suppress Hertzian cone cracking during impact with a small hammer or compression between platens. Finally, it is argued that when the compressive force on a PRD is very high, plasticity in the PRD occurs, which leads to its eventual destruction with increasing load.