Abstract: A polyvinyl alcohol-based hollow fiber membrane having a ratio between the size of particles of 90% rejection and that of particles of 10% rejection of not more than 5, thus proving to have a sharp fractionating property, is produced by a process which comprises, on producing a polyvinyl alcohol-based hollow fiber membrane by dry-jet wet spinning or wet spinning, using a spinneret having heat insulating structure.

Abstract: A polyvinyl alcohol-based hollow fiber membrane having a ratio between the size of particles of 90% rejection and that of particles of 10% rejection of not more than 5, thus proving to have a sharp fractionating property, is produced by a process which comprises, on producing a polyvinyl alcohol-based hollow fiber membrane by dry-jet wet spinning or wet spinning, using a spinneret having heat insulating structure.

Abstract: A copolyester film is disclosed which comprises a copolyester in which the dicarboxylic acid component comprises 100 to 85 mole percent of terephthalic acid and the diol component comprises 65 to 97 mole percent of 1,4-butanediol and 3 to 35 mole percent of a polyethylene glycol with a molecular weight of 106 to 550. The copolyester has a reduced viscosity in the range of 0.8 to 1.4 dl/g as measured at a concentration of 0.5 g/dl in a 1:1 (by weight) solvent mixture of phenol and tetrachloroethane at 30.degree. C. The copolyester has a main endothermic peak with a peak maximum temperature of 160.degree. C. to 200.degree. C. and at least one subsidiary endothermic peak with a peak maximum temperature of 30.degree. C. to 80.degree. C. in differential scanning calorimetry with the ratio (R) of the area occupying not less than 40.degree. C. in the subsidiary endothermic peak, the main endothermic peak area being within the range of 3 percent to 20 percent.

Abstract: An apparatus for measuring the quantities of chemical substances contained in a solution to be assayed by using a chemical-substance sensitive sensor consists of a potentiometric electrode which responds selectively to chemical substances, and a liquid-junction type reference electrode including a tube, a porous thread member housed in the front end opening of the tube and having a pore capacity of 0.2 cc/g or more and at least the surface of which is hydrophilic, a silver-silver chloride wire is provided and housed in the tube so that at one end of the wire is in contact with the thread member and the wire which extends along the tube. The wire is connected to a connector at the other end opening of the tube, an electrical insulating resin fills said tube, at least at the front end portion thereof, for fixing both the silver-silver chloride wire and the thread member by contact therewith and for stopping said tube. An internal solution is retained by suction in said porous thread member.