Cryogenics scale, both of which measure from absolute zero, rather than more usual scales such as Celsius or Fahrenheit, with their zeroes at arbitrary temperatures. The word "cryogenics" stems from Greek "κρύο (cryo)" – "cold" + "γονική (genic)" – "having to do with production". Cryogenic fluids with their boiling point in Kelvin Liquefied gases, such as liquid nitrogen and liquid helium, are used in many cryogenic applications. Liquid nitrogen is the most commonly used element in cryogenics and is legally purchasable around the world. Liquid helium is also commonly used and allows for the lowest attainable temperatures to be reached. These
Ship prefix Ship prefix A ship prefix is a combination of letters, usually abbreviations, used in front of the name of a civilian or naval ship. Prefixes for civilian vessels may either identify the type of propulsion, such as "PS" for paddle steamer, or purpose, such as "RV" for research vessel. Civilian prefixes are often used inconsistently, and frequently not at all. Sometimes a slash is used to separate the letters, as in "M/S". Naval prefixes came into use as abbreviations for longer titles, such as "His/Her Majesty's Ship" in the British Royal Navy, abbreviated "H.M.S." and then "HMS". Earlier uses often