Abstract: A material for adhesion prevention can be adhered to biological tissue with certainty and has improved tissue adhesiveness and biodegradability. Such material for adhesion prevention is composed of: a 1- to 1,000-?m-thick water-soluble support layer comprising a water-soluble polymer; and a 1- to 1,000-?m-thick adhesion prevention layer comprising a biodegradable polymer. The biodegradable polymer has a structure in which a branched polyalkylene glycol comprising 3 to 8 terminal hydroxyl groups per molecule is bound to a polyhydroxy alkanoic acid, and a mass ratio of the branched polyalkylene glycol relative to the total mass is 1% to 30%.

Abstract: A material for adhesion prevention can be adhered to biological tissue with certainty and has improved tissue adhesiveness and biodegradability. Such material for adhesion prevention is composed of: a 1- to 1,000-?m-thick water-soluble support layer comprising a water-soluble polymer; and a 1- to 1,000-?m-thick adhesion prevention layer comprising a biodegradable polymer. The biodegradable polymer has a structure in which a branched polyalkylene glycol comprising 3 to 8 terminal hydroxyl groups per molecule is bound to a polyhydroxy alkanoic acid, and a mass ratio of the branched polyalkylene glycol relative to the total mass is 1% to 30%.

Abstract: A polymer film can be adjusted to movement or a fine uneven surface of a living body and has excellent ability to adhere to a biological tissue. The polymer film includes a block copolymer having a structure in which branched polyalkylene glycol and polyhydroxyalkanoic acid are bound to each other, wherein the polymer film has a film thickness of 10 to 1000 nm. The branched polyalkylene glycol has at least three terminal hydroxyl groups per molecule, the mass percentage of the branched polyalkylene glycol relative to the total mass of the block copolymer is 1% to 30%, and a value obtained by dividing the average molecular weight of polyhydroxyalkanoic acid in the block copolymer by X that is the number of terminal hydroxyl groups present per a single molecule of the branched polyalkylene glycol is 10000 to 30000.

Abstract: A polymer film can be adjusted to movement or a fine uneven surface of a living body and has excellent ability to adhere to a biological tissue. The polymer film includes a block copolymer having a structure in which branched polyalkylene glycol and polyhydroxyalkanoic acid are bound to each other, wherein the polymer film has a film thickness of 10 to 1000 nm. The branched polyalkylene glycol has at least three terminal hydroxyl groups per molecule, the mass percentage of the branched polyalkylene glycol relative to the total mass of the block copolymer is 1% to 30%, and a value obtained by dividing the average molecular weight of polyhydroxyalkanoic acid in the block copolymer by X that is the number of terminal hydroxyl groups present per a single molecule of the branched polyalkylene glycol is 10000 to 30000.

Abstract: An image forming method and an apparatus therefor applicable to a color copier. A signal value representative of a reflection and appearing when the output of a photosensor is minimum in response to a change in the amount of toner deposition on a photoconductive element is detected. This maintains the density of a predetermined reference pattern used to sense an image density constant despite the change in, for example, the reflection characteristic of the photoconductive element. A bias for development is so changed as to maintain the output of the photosensor constant, so that the effective bias remains constant relative to the charge potential on the photoconductive element.