Abstract: A gassing unit for bubble-free introduction of process gas into a liquid in a reactor, wherein the gassing unit includes at least: first and second spaced apart gas receiving chambers, the two gas receiving chambers connected to one another via at least two two-dimensional, gas-conducting diffusion membranes including hollow fibers spaced apart from one another and at least partially fixed to one another; a gas supply receptacle on at least one gas receiving chamber; a shaft receptacle on at least one gas receiving chamber; wherein the gassing unit for gassing the liquid in the reactor is supplied with process gas via the gas supply receptacle, is set into a rotational movement via the receptacle for the shaft and forms a convection flow within the reactor via rotational movement of the gassing unit in the liquid. Further included is a method for gassing a process liquid, a gas-liquid reactor including a gassing unit, and the use of a gassing unit for supplying biological cultures with process gases.

Abstract: A process for the additive manufacturing of porous gas-permeable shaped articles by selective laser sintering of a polymer powder may include a) Providing a layer of polymer powder within an construction space; b) Heating a polymer layer to a temperature greater than or equal to 0.5° C. and less than or equal to 2.5° C. below the melting point of the polymer powder; c) Spatially resolved melting of a powder bed by means of the introduction of laser energy; wherein steps a-c) are carried out one or more times in the same construction space on consecutively superimposed powder layers and the surface energy contribution to be introduced in process step c) is greater than or equal to 1.7 times and less than or equal to 4.25 times the product of the melting enthalpy, polymer powder filling density and layer thickness of the powder filling.

Abstract: The present invention relates to a gassing unit for bubble-free introduction of a process gas into a liquid located in a reactor, wherein the gassing unit comprises at least: a first gas receiving chamber and, spaced therefrom, a second gas receiving chamber for receiving a process gas, the two gas receiving chambers being connected to one another via at least two two-dimensional, gas-conducting diffusion membranes comprising hollow fibers spaced apart from one another and at least partially fixed to one another; a receptacle for a gas supply on at least one of the gas receiving chambers; a receptacle for a shaft on at least one of the gas receiving chambers; wherein the gassing unit for gassing the liquid in the reactor can be supplied with process gas via the gas supply receptacle, can be set into a rotational movement via the receptacle for the shaft and can form a convection flow within the reactor via the rotational movement of the gassing unit in the liquid.