A crossflow filter includes a rigid cylindrical inner wall and a rigid cylindrical outer wall with an inelastic filter membrane positioned therebetween defining a retentate channel inside the filter membrane and a permeate channel outside the filter membrane. Further, the filter includes transition channels shaped and connected to the inner and outer walls to deliver a flow of fluid from an inlet port to the retentate channel and to capture flow flowing longitudinally along the cylindrical inner and outer walls from both the retentate and permeate channels to respective outlet ports.

A polyimide precursor solution includes an aqueous solvent including water, a polyimide precursor, resin particles, and an ionization agent X having a boiling point of 100° C. or more and 130° C. or less and an ionization agent Y having a boiling point of 250° C. or more and 300° C. or less.

The present invention provides a separation membrane that allows a separation functional layer to have less defects and that inhibits a flux of a permeation fluid from decreasing. A separation membrane of the present invention includes a separation functional layer, an interlayer, and a porous support member in this order in a stacking direction. The interlayer has a thickness of 0.1 μm to 2.5 μm. A total value of the thickness of the interlayer and a thickness of the separation functional layer is less than 4.0 μm. The interlayer contains a polymer compound, for example. A distance Ra between a Hansen solubility parameter of the polymer compound and a Hansen solubility parameter of H.sub.2O is less than 19 MPa.sup.1/2, for example.

The present invention provides a separation membrane that allows a separation functional layer to have less defects and that inhibits a flux of a permeation fluid from decreasing. A separation membrane of the present invention includes a separation functional layer, an interlayer, and a porous support member in this order in a stacking direction. The interlayer has a thickness of 0.1 μm to 2.5 μm. A total value of the thickness of the interlayer and a thickness of the separation functional layer is less than 4.0 μm. The interlayer contains a polymer compound, for example. A distance Ra between a Hansen solubility parameter of the polymer compound and a Hansen solubility parameter of H.sub.2O is less than 19 MPa.sup.1/2, for example.

Provided are a polyimide compound including a repeating unit having an aromatic diamine component having a specific structure in which a side-chain benzylic position is regioselectively brominated, a gas separation membrane having a gas separation layer containing the polyimide compound, and a gas separation module and a gas separation apparatus each having the gas separation membrane.

Provided are a polyimide compound including a repeating unit having an aromatic diamine component having a specific structure in which a side-chain benzylic position is regioselectively brominated, a gas separation membrane having a gas separation layer containing the polyimide compound, and a gas separation module and a gas separation apparatus each having the gas separation membrane.

Filter holders and membranes are provided that can be included within a bioreactor bag system. The filter holders and membranes include features that allow incorporation of advanced membrane materials having differing material characteristics than traditional membranes that more closely matched the characteristics of the filter holder.

Filter holders and membranes are provided that can be included within a bioreactor bag system. The filter holders and membranes include features that allow incorporation of advanced membrane materials having differing material characteristics than traditional membranes that more closely matched the characteristics of the filter holder.

Compositions of and methods for producing a modified polyimide-containing compound with an alkyl or acyl group, one method including selecting and preparing a polyimide-containing compound to undergo a Friedel-Crafts alkylation or acylation reaction; carrying out the Friedel-Crafts alkylation or acylation reaction on the polyimide-containing compound to bond an alkyl group or acyl group to a reactive site on an aromatic compound of the polyimide-containing compound; cleaving the polyimide-containing compound to produce modified monomers comprising the alkyl group or the acyl group; and using the modified monomers in a reaction to produce the modified polyimide-containing compound, wherein the alkyl group or the acyl group is present in the modified polyimide-containing compound.

Compositions of and methods for producing a modified polyimide-containing compound with an alkyl or acyl group, one method including selecting and preparing a polyimide-containing compound to undergo a Friedel-Crafts alkylation or acylation reaction; carrying out the Friedel-Crafts alkylation or acylation reaction on the polyimide-containing compound to bond an alkyl group or acyl group to a reactive site on an aromatic compound of the polyimide-containing compound; cleaving the polyimide-containing compound to produce modified monomers comprising the alkyl group or the acyl group; and using the modified monomers in a reaction to produce the modified polyimide-containing compound, wherein the alkyl group or the acyl group is present in the modified polyimide-containing compound.