Tin pest related problems such as tin whiskers. At 13.2 °C (about 56 °F) and below, pure tin transforms from the silvery, ductile metallic allotrope of β-form "white tin" to the brittle, nonmetallic, α-form "grey tin" with a diamond cubic structure. The transformation is slow to initiate due to a high activation energy but the presence of germanium (or crystal structures of similar form and size) or very low temperatures of roughly −30 °C aids the initiation. There is also a large volume increase of about 27% associated with the phase change to the nonmetallic low temperature allotrope. This frequently makes tin
Puyo Puyo! 15th Anniversary Puyo Puyo! 15th Anniversary Ms. Accord, the teacher at the Primp Magic School, informs Sig that there will be a tournament up for play, and everyone's competing; the reward is a medal that will grant anyone's single wish. Another scene shows Amitie and Arle pledging to play by the rules, and Sig, still as clueless as ever, eventually plegdes as well, but not before witnessing six comets fall down onto Earth. Sig, realising that this is a big discovery, decides to ignore it anyhow and goes onto the competition. It turns out that the "comets" are actually six familiar characters