Those 4 are circled in blue. Next we add the Aluminum atoms, connecting their tetrahedra. You'll notice that the 4 outer tetrahedra, and the 4 inner Mg atoms sit on spots mirroring eachother. Lastly ...
They sit on the corners of tetrahedra which share corners infinitely in 3 dimmensions, an array known as a Kagome net. The image below shows only the Al atoms sitting on the corners of tetrahedra. Now ...
He demonstrated that DNA strands could be designed to self-assemble into complex shapes, such as cubes, tetrahedra, and other polyhedral. This approach, known as structural DNA nanotechnology, has ...