Abstract: A method of producing a useful high-molecular-weight substance by culturing animal cells capable of proliferation, which comprises (A) a culturing step of culturing said animal cells in suspension to form a suspension culture mixture containing the animal cells and a useful high-molecular-weight substance produced by the animal cells; (B) a separating step of separating the animal cells from the suspension culture mixture and withdrawing the culture medium; (C) a removing step of removing low-molecular-weight substances inhibiting the growth of the animal cells from the culture medium, said inhibitor substances being the metabolites of the animal cells and different from the useful high-molecular-weight substance; (D) a recycling step of recycling part or the whole of the culture medium left after removal of the growth-inhibiting low-molecular-weight substances to the culturing step (A); and (E) a recovering step of recovering the useful high-molecular-weight substance accumulated in the culture system.

Abstract: Adherent 293 human kidney cells are continuously cultured in suspension in serum-free medium. Fresh medium is fed into a culture vessel and spent medium is withdrawn from the vessel. The 293 cells are maintained in small aggregates in suspension at a density of at least 3.times.10.sup.6 cells/ml for 30 days. The formation of large cell clumps is prevented by maintaining the concentration of calcium in the serum-free medium at 0.002 mM to 0.3 mM.

Abstract: A method of cultivating animal or plant cells, which consists essentially of contacting a cultivation liquor having animal or plant cells suspended therein with a liquid fluorocarbon having molecular oxygen dissolved therein, characterized in that said cultivation liquor forms a continuous suspension phase which has cell densities of at least 4.times.10.sup.6 cells/ml, that said contact is made by feeding said liquid fluorocarbon into the cultivation liquor from above the cultivation liquor such that 1 ml of liquid fluorocarbon has a surface area of about 6 to about 300 cm.sup.2 whereby the liquid fluorocarbon falls downward through the cultivation liquor by gravity, and that said cultivation liquor has a volume of at least about 10 liters.

Abstract: An apparatus for cell culture by perfusion comprising a cell culture tank for suspension culture, said cell culture tank having a suspension cell culture zone, a cell settling zone, an opening for discharging a spent culture medium from the settling zone and an opening for supplying a culture medium to the suspension culture zone, the suspension culture zone and the setting zone being separated by a partition therebetween in a manner to communicate with each other in the lower portion of the settling zone, and the settling zone being formed between the side wall of the cell culture tank and the partition. Another type of apparatus for cell culture having a unit in which main culturing and settling are carried out in a cell settling zone, and a multiunit cell culture apparatus having at least two culturing units which are stacked longitudinally are also described.

Abstract: A fire-resistant thermoplastic polyester resin composition having excellent anti-dripping properties which comprises(A) an aromatic polyester resin,(B) a graft copolymer of a butadiene polymer-vinyl monomer in an amount of at least 0.5 parts by weight but less than 25 parts by weight per 100 parts by weight of said polyester resin (A),(c) a fire retardant in an amount of from 0.5 to 35 parts by weight per 100 parts by weight of said polyester resin (A).

Abstract: A fire-retardant thermoplastic polyester resin composition free from "dripping" comprising(A) 100 parts by weight of an aromatic polyester resin,(B) from 0.5 to 100 parts by weight of an alkaline earth metal carbonate, and(C) from 0.5 to 50 parts by weight of a fire retardant.

Abstract: In the process for preparing alkenylbenzene by the catalytic reaction of alkylbenzenes and 1,3-butadiene in the presence of an alkali metal catalyst, the improvement which comprises effecting the preliminary contact of the freshly fed alkylbenzene with the reaction product of said catalyst reaction and thereafter catalytically reacting said alkylbenzene with said 1,3-butadiene.

Abstract: A process for the preparation of alkyltetralins which comprises feeding an alkenylbenzene into a reaction zone continuing a fixed bed of an acidic cyclization catalyst, and cyclizing it in the liquid phase at a temperature not higher than about 300.degree. C., characterized in that:I. at least a part of the reaction mixture containing the unreacted alkenylbenzene, which has been withdrawn from said reaction zone and in which the conversion of alkenylbenzene is below the intended final conversion, is cooled, and at least a part of the cooled reaction product in an amount sufficient to adjust the temperature of the reaction zone to not higher than about 300.degree. C. is recycled to said reaction zone, andIi. the remainder of the reaction product is led into another reaction zone containing a fixed bed of acidic cyclization catalyst, and without the aforesaid recycling, further cyclized in the liquid phase until the intended final conversion is attained.

Abstract: A process for preparing 2,6-dimethylnaphthalene by the selective isomerization of an isomeric mixture of dimethylnaphthalenes(DMN), characterized in that1. the weight ratio of DMN of group A which includes 2,6-DMN, 1,6-DMN, and 1,5-DMN to other DMN (not belonging to group A) in the isomerization reactant is adjusted to not more than 12,2. the weight percent of 2,6-DMN in the reaction product is adjusted to at least 27 based on the DMN of group A contained therein,3. the disproportionation ratio D (weight percent) of other DMN (not belonging to group A) and the conversion G (weight percent) of DMN of group A to other DMN satisfy the relation expressed by D.ltoreq. -0.9G + 6.76, and4. the residue in the crystallization step is recycled to the isomerization step.

Abstract: In the method wherein an alkenylation reaction product liquid obtained by the alkenylation reaction of an alkylbenzene and a C.sub.4 - C.sub.5 conjugated diene in the presence of alkali metal catalysts and containing unreacted alkylbenzene, alkali metal catalysts and organo-alkalimetal compounds is conveyed to a distillation zone at which said alkenylation reaction product liquid is separated by distillation to recover an alkenylbenzene-containing fraction and an unreacted alkylbenzene-containing fraction, the improvement which comprises adjusting the total of the concentrations of said alkali metal catalysts and organo-alkalimetal compounds in said alkenylation reaction product liquid introduced to the distillation zone so as to be 0.09 - 15 milligram atoms per kilogram of said product liquid, calculated as alkalimetal atoms, and thereafter conducting the distillation of said product liquid under conditions of non-addition of alcohols.

Abstract: In the process for preparing monoalkenylbenzenes by reacting an alkylbenzene and a C.sub.4 - C.sub.5 conjugated diene in the presence of an alkali metal catalyst while passing the reactants progressively through a series of successive reaction zones substantially isolated from each other under non-back-flow conditions, the reaction being carried out at this time while feeding said alkylbenzene and alkali metal catalyst to the first reaction zone and the conjugated diene separately to at least two of said zones, and thereafter withdrawing the reaction product from the final reaction zone of said series; the improvement which comprises (1) reacting the reactants including the alkylbenzene, C.sub.4 - C.sub.