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 from the Madou series, who serve as boss characters in the story modes. As "Puyo Puyo! 15th Anniversary" was created to commemorate the fifteenth anniversary of Puyo Puyo, it includes most of the "Fever" characters plus six of the characters from the "Madou" series; they are said to have fallen from the sky into Primp Town, the primary setting of the Fever series games. There are a total of twenty-two characters in this game. 15th Anniversary has a slew of new modes, and also includes modes that emulate the original "Puyo Puyo", "Puyo Puyo Tsu" and "Puyo Pop Fever". In