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I think you can apply Euler Bernoulli beam theory. This means that the highest stress should take place closest to the wall. Why a tree branch does not break there is because it gets thicker closer to the trunk spreading the load over more material.


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It looks like you're asking about some sort of smart material, specifically a shape-memory polymer. Something, maybe, like this from inventables, or this from CRG. You could check out this from NCSU Now, if you mean textile as in cloth, I'm afraid I could not easily find one. Of course, many of these gels/polymers could be put into cloth, and may yield the ...


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To add to the replies above, you must remember that hardness tests (like Vickers or Rockwell) measure the ability of a material to resist permanent (plastic) deformation. So in practice, you take a very hard material, like diamond, and use it to indent a range of other materials. You usually don't want the indenter and indented material to have similar ...


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As John says, the Mohs criterion is useful because it may be immediately applied. One may try to rob the two materials with any force but the magnitude of the force really doesn't matter because once the force exceeds a certain threshold, the materials' atoms or molecules start to rearrange. Scratches – whatever is their exact definition – will begin to ...


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The Mohs scale is useful because you don't need any special equipment to do the tests so it can be used in the field to help identify minerals. It is not as precise as tests like the Vickers hardness nor is it intended to be. In practice it's usually obvious which mineral is scratching which. As it happens there was a recent related question at Glass ...


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There is apparently a whole industry dedicated to this (relevant google search near infrared reflective coating For instance, see this paper in Thermal Performance: Special Infrared Reflective Pigments Make a Dark Roof Reflect Almost Like a White Roof by Bill Miller et al. As user3384414 pointed out, nearly half of the solar radiance is outside the ...


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As only about 50 % of the energy of the light is in the visible spectrum is in the visible area (Wikipedia) this should be at least theoretically possible. So you would get with a close to perfect t-shirt only 50% of the energy. Whether such materials do exist, I don't know. I guess there are some materials fulfilling the condition, but I don't know whether ...


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It has been engineered, based on observations hair patterns of insects (Droplet slides down when substrate is oriented so that the hairs point downwards, while it was attached in the first two orientations)


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I've been having a play with some granulated and some icing suger (I think "icing sugar" is the same as "powdered sugar") and the thing that strikes me is that icing sugar is less free flowing than granulated sugar. I would guess this is the reason for the density difference. You mention in a comment that the packing fraction for spheres does not depend on ...


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I have recently published a paper on Zn3N2 nanocrystals (http://pubs.rsc.org/en/content/articlelanding/2014/tc/c4tc00403e#!divAbstract). The material appears to have a direct band gap around 1eV and makes nice nanophosphors so if you can work out how to p and n dope it I am sure you could make an LED.



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