Abstract: Disclosed herein is a recording medium comprising a base material, the surface of which is coated with a composition comprising, as an essential component, a polymer having a weight average molecular weight of not less than 20,000 which is obtained by reacting a polyvalent carboxylic acid, or anhydride or lower alkyl ester thereof with a polyhydroxyl compound having a weight average molecular weight of not less than 1,000 obtained by adding ethylene oxide and/or propylene oxide to a compound having 2 to 4 active hydrogen atoms.

Abstract: A cryogenic cooling apparatus including a vacuum container for containing an object to be cooled, at least one refrigerator for cooling the object, and a thermal switch unit. The refrigerator has a high-temperature cooling stage and a low-temperature cooling stage connected to the high-temperature cooling stage via a low-temperature cylinder. The thermal switch unit has at least one high-temperature heat transfer member attached to the high-temperature cooling stage, at least one low-temperature heat transfer member attached to the low-temperature cooling stage and separated from the high-temperature heat transfer member, and a sealed container provided between the high-temperature cooling stage and the low-temperature cooling stage.

Abstract: A recording medium contains, within an ink absorbent substrate per se or in an ink receiving coat layer formed on a substrate, basic magnesium carbonate together with a cationic surfactant and/or a nonionic surfactant. The recording medium is suitably used for color ink jet recording of the both-ways serial printing type and eliminates substantially the tone difference between forward and backward printings and the discoloration during indoor storage.