Abstract: The purpose of the present invention is to provide a viscous composition which is capable of achieving a high viscosity over a pH range from acidic to weakly acidic conditions even in the presence of a polyvalent metal salt by means of an alkyl-modified carboxyl group-containing water-soluble copolymer. A viscous composition, which is obtained by adjusting the pH of a liquid composition that contains a specific alkyl-modified carboxyl group-containing water-soluble copolymer, a polyvalent metal salt and water to 7.0 or more with use of a base, and then adjusting the pH of the resulting liquid composition to 2.5-6.5 with use of a carboxylic acid and/or a phosphorus oxo acid, is able to have a high viscosity.

Abstract: An optical element, which has an antireflection performance offering excellent wavelength band characteristics and incident angle characteristics, includes a substrate and structures that each are formed of a convex portion and that are arranged in plural on a surface of the substrate at a fine pitch equal to or less than a wavelength of light. Each of the structures has a quadrangular pyramid shape or a truncated quadrangular pyramid shape that has a quadrangular bottom surface, and each of four sides that farm the quadrangular bottom surface is curved toward a center of the bottom surface.

Abstract: An object of the present invention is to provide a gel-like cosmetic material the viscosity of which is not easily reduced even in the presence of an electrolyte, the cosmetic material ensuring an unconventional jelly-like feel when being applied to the skin, and a smooth sensation after being applied to the skin. The present invention provides a gel-like composition comprising 0.3 to 3 mass % of an alkyl-modified carboxyl-group-containing water-soluble polymer, 3 to 20 mass % of a polyhydric alcohol, and 0.25 to 5 mass % of an inorganic salt, the alkyl-modified carboxyl-group-containing water-soluble polymer being (i) a polymer obtained by polymerizing a (meth)acrylic acid and a C18-24 alkyl-containing (meth)acrylic acid alkyl ester, or (ii) a polymer obtained by polymerizing a (meta)acrylic acid, a C18-24 alkyl-containing (meth)acrylic acid alkyl ester, and a compound having two or more ethylenically unsaturated groups.