{HEAD ~ The bond structure} of this material provides physical properties approaching those of diamond, including {TAIL ~ a hardness} of over about 50 GPa, with certain species having hardness of up to about 80 GPa 
{ HEAD ~ The bond structure } of this material provides physical properties approaching those of diamond , including { TAIL ~ a hardness } of over about 50 GPa , with certain species having hardness of up to about 80 GPa
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