Abstract: An image forming apparatus has a book binding mechanism for performing a book bind operation using front sheets of a plurality of sizes which can bind a bundle of sheet members recorded by said image forming apparatus, and have limitations on the numbers of recorded sheet members to be bound. The image forming apparatus further has output means for outputting sheet number data according to a bundle of sheet members; judge means for judging whether or not the sheet number data output from said output means is larger than a range of the limitation; detect means for, when the judged result from said judge means is affirmative, dividing the sheet number data, and detecting a divided sheet number value which falls within the range of the limitation; and control means for controlling to perform a book bind operation in units of the sheet numbers detected by said detect means.

Abstract: Disclosed is a hardening material comprising (a) a powder component composed of a powdery mixture of tetracalcium phosphate and calcium phosphate having a Ca/P atomic ratio lower than 1.67 and (b) a liquid component composed of a colloidal aqueous solution comprising solid colloid particles dispersed in an aqueous medium, wherein said components (a) and (b) are independently packed and both the components are mixed for hardening.This hardening material can give a hardened body having a high strength without showing any harmful action on a living body. Accordingly, this hardening material is especially effectively used for the restoration of a hard tissue of a living body.

Abstract: Disclosed is a prosthetic composition comprising (A) a diester monomer represented by the following formula: ##STR1## wherein R.sub.1 stands for an alkylene group having 2 to 6 carbon atoms andR.sub.2 stands for an alkyl group having 2 to 4 carbon atoms,or a mixture of said diester monomer and other monomer copolymerizable therewith, (B) an orgnic polymer soluble in the monomer (A) in an amount of 0.5 to 5 parts by weight per part by weight of said monomer (A) and (C) a radical polymerization initiator.

Abstract: Disclosed is an acrylate compound represented by the following general formula: ##STR1## wherein R.sub.1 stands for a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, R.sub.2 stands for an alkylene group having 2 to 20 carbon atoms, R.sub.3 stands for a hydrogen atom or an alkyl group having 1 to 20 carbon atoms when n is 1, and n is 1 or 2.A composition comprising this acrylate compound as one component has an excellent adhesiveness.