Abstract: A riblet structure according to the present technology includes a plurality of riblets that are arranged in a width direction and each include a first wall portion and a second wall portion, the first wall portion being vertically provided to be substantially perpendicular to a bottom portion, the second wall portion including an inclined portion connected to the first wall portion at an apex portion and inclined with respect to a perpendicular direction at a predetermined angle.

Abstract: A wavelength converter includes a first phosphor activated with Cr3+; and a second phosphor activated with at least one ion of Ce3+ or Eu2+. A fluorescence spectrum of a fluorescence emitted by the second phosphor has a peak where a fluorescence intensity shows a maximum value in a wavelength range of 500 nm or more to less than 580 nm. The wavelength converter emits a fluorescence having a light component over an entire range of 500 nm or more to less than 580 nm. The wavelength converter emits a light having a spectrum in which a ratio of a minimum light emission intensity to a maximum light emission intensity is 40% or less in a wavelength range of 550 nm or more to 700 nm or less.

Abstract: A riblet structure includes a plurality of wave-shaped riblets on a surface thereof, in which each of the riblets has a smaller peak height as an angle formed between a ridge line and a fluid flow direction becomes larger, a width between peak bases in a direction orthogonal to the fluid flow direction becomes smaller as the angle becomes larger, and an angle formed between a slope of a peak of the riblet and the surface at the peak base or a curvature at the peak base is identical at any position in a cross-sectional shape in the direction orthogonal to the fluid direction.

Abstract: A polyurethane precursor-containing woody material that includes a woody raw material that is impregnated with a blocked isocyanate compound and a polyethylene glycol. The polyethylene glycol is represented by a formula: HO—(CH2—CH2—O), —H (n=1 to 12,000). The blocked isocyanate compound is a compound which is formed from an isocyanate compound and a blocking agent that protects an isocyanate group contained in the isocyanate compound, and is inactivated by a group derived from the blocking agent.

Abstract: A woody material, where a ratio (HB/HA) between a height (HA) of an absorption peak derived by C?H stretching vibration detected at a wavenumber from 2850 cm-1 to 2950 cm-1 and a height (HB) of an absorption peak derived by skeletal vibration of an aromatic ring detected at a wavenumber from 1480 cm-1 to 1540 cm-1 is 1.10 or less in an ATR spectrum of an inside or a surface of the woody material by an infrared spectroscopic analysis method.