Nature has taught scientists that there is a critical size — 30 nanometers — below which tiny structures become insensitive to flaws.

Research conducted at the Max Planck Institute for Metals Research in Germany and the Austrian Academy of Sciences has found that the size of mineral particles in biological materials such as bone and tooth evolved for optimum strength and maximum tolerance of flaws.

At less than 30 nanometers, particles become insensitive to flaws and have strength equivalent to that of a perfect crystal.

The finding, reported in the Proceedings of the National Academy of Sciences, will affect how engineers design nanoscale structures, removing the need for concern about the engineering concept of stress concentration at flaws.
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