Abstract: A light emitting device using a group III nitride group compound semiconductor is disclosed. The device includes a substrate, a group III nitride group compound semiconductor layer, and a rectangular parallelepiped stack Rd which is formed by etching multiple group III nitride group compound semiconductor layers laminated on the group III nitride group compound semiconductor layer. The group III nitride group compound semiconductor layer comprises regions, which have many defects and less defects, respectively, and are formed in a striped pattern. Each of the boundaries between the regions with less defects and more defects or a plane which includes a longitudinal edge of the buffer layer is vertical to the substrate and parallel to a longitudinal plane of the rectangular parallelepiped stack Rd. The boundaries and two stack facets Mrr of the rectangular parallelepiped stack Rd are parallel to each other.

Abstract: A light emitting device using a group III nitride group compound semiconductor is disclosed. The device includes a substrate, a group III nitride group compound semiconductor layer, and a rectangular parallelepiped stack Rd which is formed by etching multiple group III nitride group compound semiconductor layers laminated on the group III nitride group compound semiconductor layer. The group III nitride group compound semiconductor layer comprises regions, which have many defects and less defects, respectively, and are formed in a striped pattern. Each of the boundaries between the regions with less defects and more defects or a plane which includes a longitudinal edge of the buffer layer is vertical to the substrate and parallel to a longitudinal plane of the rectangular parallelepiped stack Rd. The boundaries and two stack facets Mrr of the rectangular parallelepiped stack Rd are parallel to each other.

Abstract: A polyester elastomer composition comprising a polyester block copolymer and a compound having, in one molecule, not less than two functional groups capable of reacting with a terminal group of the polyester block copolymer, and showing (A) a weight loss (volatility) at 150.degree. C., 2 hours of not more than 0.4% and (B) a gelation degree (gel fraction) at 250.degree. C., 4 hours of not more than 50%; and a polyester elastomer composition comprising a polyester block copolymer, a compound having, in one molecule, not less than two functional groups capable of reacting with a terminal group of the polyester block copolymer and a chain extender heating loss percentage satisfying the formula: (W1-W2)/W1.ltoreq.0.1, and a stabilizer comprising a tertiary amine as a part of its skeleton. From such composition, an elastomer molded product having fine mechanical strength, heat resistance and resistance to hydrolysis, which shows less volatility during heating and less gel and bleed out, can be obtained.

Abstract: A polyester resin composition having excellent gas barrier properties and transparency which comprises 100 parts by weight of a thermoplastic polyester resin (A), 1 to 100 parts by weight of a polyamide resin having metaxylylene group (B) and 0.01 to 50 parts by weight of a compatibilizing agent (C); and a polyester hollow molded article in the form of a single or multi-layered hollow molded article, wherein at least one of the layers is made of the above polyester resin composition.

Abstract: A mixture consisting essentially of (1) an organic polyisocyanate compound and/or a prepolymer having terminal isocyanate residues, which is derived from the reaction of an organic polyisocyanate with a polyhydroxyl compound, and (2) 2-pyrrolidone, is injected for grouting into water-leaking cracks or openings of concrete structures such as water tanks, subway constructions and tunnels. The injected mixture diffuses into the cracks or openings and is cured in short time by reacting with water at the leaking sites. The resultant polyurethane foam securely seals the water leaking sites.