Abstract: A cellulose ether that is predominantly substituted in the C3 position of the anhydroglucose unit of the cellulose is described. In an embodiment of the present invention, the partial degree of substitution in the C3 position of the cellulose ether is ?60%, based on the total degree of substitution.

Abstract: Finely divided polysacharide derivatives are described. The finely divided polysacharide derivatives are prepared by a process comprising: a) forming an aqueous composition comprising a polysaccharide derivative and water, in which the polysaccharide derivative is soaked or dissolved; b) converting the polysaccharide derivative of the aqueous composition into finely divided solid particles by, (i) contacting the aqueous composition with superheated water vapor in a dryer-pulverizer; or (ii) causing the polysaccharide derivative of the aqueous composition to flocculate; and c) optionally drying the finely divided solid particles of step b). The primary structures of the polysaccharide starting material are largely removed, and the product has a shape factor of less than 5 and greater than or equal to 1.

Abstract: Cellulose ethers with a specific substitution pattern, wherein they are substituted predominantly in the C3 position of the anhydroglucose unit of the cellulose.

Abstract: A cellulose ether that is predominantly substituted in the C3 position of the anhydroglucose unit of the cellulose is described. In an embodiment of the present invention, the partial degree of substitution in the C3 position of the cellulose ether is ≧60%, based on the total degree of substitution. Also described is a process for preparing the cellulose ether of the present invention. The process involves, reacting cellulose, dissolved in N-methylmorpholine-N-oxide monohydrate (NMMNO) and optionally other inert organic solvents, with alkylation reagents. The reaction takes place in the presence of: (i) an insoluble solid phase catalyst, e.g., solid ion exchange resins based on polystyrene having quaternary ammonium groups; (ii) stabilizers, e.g., propyl gallate; and (iii) optionally additional soluble co-catalysts, e.g., trimethylbenzylammonium hydroxide.

Abstract: Finely divided polysacharide derivatives are described. The finely divided polysacharide derivatives are prepared by a process comprising: a) forming an aqueous composition comprising a polysaccharide derivative and water, in which the polysaccharide derivative is soaked or dissolved; b) converting the polysaccharide derivative of the aqueous composition into finely divided solid particles by, (i) contacting the aqueous composition with superheated water vapor in a dryer-pulverizer; or (ii) causing the polysaccharide derivative of the aqueous composition to flocculate; and c) optionally drying the finely divided solid particles of step b). The primary structures of the polysaccharide starting material are largely removed, and the product has a shape factor of less than 5 and greater than or equal to 1.

Abstract: The invention relates to a new, particularly economic process for preparing pulverulent polysaccharide derivatives, in particular cellulose derivatives, having a thermal flocculation point; the process comprises soaking or dissolving the polysaccharide derivative in a solvent or mixed solvent, dividing/comminuting the soaked or dissolved polysaccharide derivative by thermal and/or mechanical liquid separation and an optional drying step.

Abstract: A system for continuous production and removal of a biological substance from a dispersed cell culture. The system comprises a reactor adapted to maintain the cell culture under incubating conditions and means for pumping limited volumes of the culture fluid from the reactor and through an external substance separation device adapted to extract the substance in a limited time on a continuous basis without collection of, or damage to, the dispersed cells. Less than 5% of the total culture fluid volume is outside the reactor (Volume outside or Vo) at any time and a given dispersed cell is outside the protective environment of the reactor for less than about two minutes, as expressed by the following relationship, ##EQU1## In preferred embodiments the external device comprises a plurality of substance-extracting, porous, hollow fibers through which the culture fluid, substance, and dispersed cells are continuously passed.

Abstract: The screw centrifuge has a cylindrical clarifying part and a conical desiccating part which is provided with axial supply pipes for a washing liquid and with openings for the passage of the washing liquid into the chamber between the drum and the screw core. A substantial improvement in the washing effect is achieved in that the openings are connected to a liquid distributor which is positioned along a cylindrical helix and which charges the washing liquid regularly along the screw flank over at least one turn in the vicinity of the screw core. The liquid distributor either comprises an overflow channel which is positioned in or directly upstream of the screw flank, or it is formed from a compact series of nozzles which are directed at the screw flank. It is an essential feature of this arrangement that the solids which are pushed up by the screw flanks are covered and saturated regularly with the washing liquid.

Abstract: A process for the purification and isolation of cellulose or starch ethers wherein directly after the etherification step the suspension agent and the extraction of the ether product with the purifying agent is carried out on the same continuously working filter.

Abstract: A process for purification and working-up of cellulose or starch ethers using a solid-jacket sieve centrifuge for removing the suspension agent extraction with purifying agent and isolation of the purified ether product.