Point groups in three dimensions the finite subgroups of SO(3), are: the cyclic groups "C" (the rotation group of a canonical pyramid), the dihedral groups "D" (the rotation group of a uniform prism, or canonical bipyramid), and the rotation groups "T", "O" and "I" of a regular tetrahedron, octahedron/cube and icosahedron/dodecahedron. In particular, the dihedral groups "D", "D" etc. are the rotation groups of plane regular polygons embedded in three-dimensional space, and such a figure may be considered as a degenerate regular prism. Therefore, it is also called a "dihedron" (Greek: solid with two faces), which explains the name "dihedral group". The rotation group of
Three-dimensional quartz phenolic Three-dimensional quartz phenolic Three-dimensional quartz phenolic (3DQP) is a phenolic-based material composed of a quartz cloth material impregnated with a phenolic resin and hot-pressed. When cured, 3DQP can be machined in the same way as metals and is tough and fire-resistant. 3DQP is used for the manufacture of nuclear weapon re-entry vehicles (RV). The quartz material 'hardens' the RV protecting the nuclear warhead against high-energy neutrons emitted by exo-atmospheric Anti-ballistic missile (ABM) bursts before re-entry. 3DQP was first used on the British Chevaline improved front end (IFE) for the Royal Navy's UGM-27 Polaris system that was in service from 1982