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In physics, cryogenics is the study of the production and behaviour of materials at very low temperatures. It is not well-defined at what point on the temperature scale refrigeration ends and cryogenics begins, but scientists assume it starts at or below . The National Institute of Standards and Technology has chosen to consider the field of cryogenics as that involving temperatures below . This is a logical dividing line, since the normal boiling points of the so-called permanent gases (such as helium, hydrogen, neon, nitrogen, oxygen, and normal air) lie below −180 °C while the Freon refrigerants, hydrogen sulfide, and other common refrigerants have boiling points above −180 °C. (above −150 °C, −238 °F or 123 K). A person who studies elements that have been subjected to extremely cold temperatures is called a cryogenicist. Cryogenicists use the Kelvin or Rankine temperature scales. == Definitions and distinctions == ; Cryogenics: The branches of physics and engineering that involve the study of very low temperatures, how to produce them, and how materials behave at those temperatures. ; Cryobiology: The branch of biology involving the study of the effects of low temperatures on organisms (most often for the purpose of achieving cryopreservation). ; Cryosurgery: The branch of surgery applying very low temperatures (down to −196 °C) to destroy malignant tissue, e.g. cancer cells. ; Cryoelectronics: The field of research regarding superconductivity at low temperatures. ; Cryotronics: The practical application of cryoelectronics. ; Cryonics: Cryopreserving humans and animals with the intention of future revival. "Cryogenics" is sometimes erroneously used to mean "Cryonics" in popular culture and the press.〔(【引用サイトリンク】title=Cryonics is NOT the Same as Cryogenics )〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「cryogenics」の詳細全文を読む スポンサード リンク
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