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Posts by muppetry

 Exactly correct. Scratch resistance is dominated by hardness, while crack resistance is determined by both tensile strength and strain to failure.  In other words there are at least a couple of different reasons why a material may resist cracking: (1)  It has high strain to failure and will support substantial deformation without tensile failure (e.g. many plastics and ductile metals), but is not necessarily strong, and could be very weak. (2)  It has high tensile...
 I don't think everyone is saying that but, in any case, it is a misleading statement. Brittle simply means low strain to failure, but since strain is a function of stress, related by the appropriate modulus (in the elastic regime) and more complete constitutive equation (in the plastic regime), brittleness alone says nothing about ease of fracture. Sapphire is quite brittle, but also much stronger (especially in tension - which controls crack formation), and, if used on...
 Some email clients, including web-based ones, allow you to request receipts (it's just an additional header item) but they will only be returned if the recipient instructs his or her email client to do so.  Apple Mail does not request or send read receipts.
It just means that you have to press the "Load images" button in an email with linked (rather than embedded) images to view the images.
 It's not embedded programs that you need to worry about - it's linked images.  They add images to the email with unique URLs that let them know when you retrieve the image. Under Mail > Preferences > Viewing, ensure that "Display remote images in HTML messages" is unchecked.
 Looks similar - just doesn't necessarily require the additional device plugged into the vehicle.
 The fact that Al2O3 is used for bearings does not mean that it will feel smoother than glass - that depends more on polishing and surface treatments. And the coeffiecient of friction depends on the two materials interacting, not just one of them, so µsapphire-steel does not tell you anything about µsapphire-skin even without surface treatment, especially since the interaction mechanisms are quite different. 
The level of polishing and surface finish will determine the feel more than the material composition. The density difference, while large, will make no difference to the feel. The thermal diffusivity of sapphire is much higher, so thick elements feel colder than glass, but these wafers are quite thin, and may equilibriate too fast for that to be very noticeable.
 That was what I meant - was that the ruse that you meant?
 To try to restrain the outlandish WS predictions next time?
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