Abstract: Disclosed is a hydrophobic porous membrane with a polymer having fluorinated alkyl side chains held in physical contact with the surface of a polyolefin porous membrane in which the fluorinated alkyl side chains of the polymer are crystallized, as well as its manufacturing process. Also disclosed is a hydrophobic porous membrane with a fluorinated crosslinked polymer from a fluorinated monomer with a fluorinated alkyl side chain and a crosslinking monomer held in physical contact with the surface of a polyolefin porous membrane, in which the fluorinated alkyl side chains of the fluorinated crosslinked polymer are crystallized, as well as its manufacturing process. These porous membranes use polyolefin porous membranes having a higher mechanical strength and lower costs than the fluorinated polymer porous membranes and still provide superior hydrophobicity over polytetrafluoroethylene type membranes.

Abstract: A heat-resisting porous membrane comprises a porous polyolefin membrane having a crosslinked copolymer held on at least a part of the pore surfaces thereof, the crosslinked copolymer being composed of a monomer (A) comprising at least one multifunctional (meth)acrylate and a monomer (B) comprising at least one monofunctional (meth)acrylate having a hydrocarbon radical of 5 to 20 carbon atoms; and the heat-resisting porous membrane can be hydrophilized by additionally having a crosslinked polymer thereon. These heat-resisting porous membranes can be used in hot water for a long period of time without deteriorating the mechanical properties inherently possessed by the matrix of the porous membrane.

Abstract: A method for culturing cells by supplying oxygen to a culture medium through a multilayer composite membrane consisting of a porous layer(s) and a nonporous layer(s) having a thickness of less than 10 micrometers laminated one after the other. By using this multilayer composite membrane for supplying oxygen to the culture medium, oxygen can be supplied to the culture medium and/or the culture broth without causing foaming in the culture medium, cell growth inhibition or reduction in productivity of cellular products.

Abstract: A process for the preparation of an organic ester of ascorbic acid or erythorbic acid represented by the general formula (II) or (III): ##STR1## wherein R.sub.1 is alkyl, aralkyl, or aryl, by reacting ascorbic acid or erythorbic acid with an organic acid or an ester thereof of the general formula (I) :R.sub.1 COOR.sub.2 (I)wherein R.sub.1 is as defined above and R.sub.2 is hydrogen, methyl, ethyl or propyl, in an organic solvent in the presence of an ester hydrolase.

Abstract: A process for the preparation of an organic ester of ascorbic acid or erythorbic acid represented by the general formula (II) or (III): ##STR1## wherein R.sub.1 is alkyl, aralkyl, or aryl, by reacting ascorbic acid or erythorbic acid with an organic acid or an ester thereof of the general formula (I):wherein R.sub.1 is as defined above and R.sub.2 is hydrogen, methyl, ethyl or propyl, in an organic solvent in the presence of an ester hydrolase.

Abstract: High molecular weight hyaluronic acid can be efficiently produced by incorporating one or more compounds having at least one aromatic ring to which one or more hydroxyl groups are attached into a medium for producing hyaluronic acid by a bacterium capable of producing hyaluronic acid. By using this method, a sufficient amount of hyaluronic acid can be easily obtained without decomposing the high molecular structure of hyaluronic acid so that the process for isolating and purifying hyaluronic acid from the medium can be simplified.