A method for producing permselective membrane includes preparing a support membrane having selective permeability and a lipid membrane containing a channel substance, the lipid membrane being formed on a surface of the support membrane. Excess lipids are removed with an acid or an alkali, and the support membrane has a permeation flux of 20 L/(m.sup.2.Math.h) or more and a desalination capacity of 1% to 20% at a pressure of 0.1 MPa.

Porous liquid-filtering membranes are provided having a boundary region substantially surrounding the pore region and having greater tear resistance than the pore region.

Provided is a hollow fiber membrane that is excellent in water vapor separation performance immediately after production and water vapor separation performance after repeated use with compressed air. A hollow fiber membrane comprising a polyarylate resin, wherein the hollow fiber membrane includes a skin layer on at least one of inner and outer surfaces, has a tensile strength of 7 MPa or more and an elongation at break of 15% or more, and has an internal pressure water permeability of less than 100 L/(m.sup.2.Math.atm/h) as measured using pure water at 25° C.

A flat ceramic membrane 1 has a plate-shaped porous support 21 made of ceramics and a filtration membrane 22 formed on an outer surface of the porous support 21. A plurality of water collection channels 2 where filtrate water obtained by permeation of water-to-be-treated through the filtration membrane 22 flows are formed inside the porous support 21. Further, a region where a thickness between a membrane surface 20 of the filtration membrane 22 and the water collection passage 2 is different is ensured inside the porous support 21.

A substrate for a liquid filter, which includes a polyolefin microporous membrane, the polyolefin microporous membrane having a water permeation efficiency of 0.10 to 0.50 ml/min.Math.cm.sup.2, the polyolefin microporous membrane having a bubble point of 0.50 MPa or more and 0.80 MPa or less.

A substrate for a liquid filter, which includes a polyolefin microporous membrane, the polyolefin microporous membrane having a water permeation efficiency of 0.51 to 1.20 ml/min.Math.cm.sup.2, the polyolefin microporous membrane having a bubble point of 0.45 MPa or more and 0.70 MPa or less, the polyolefin microporous membrane having a compressibility of less than 15%.

A substrate for a liquid filter, which includes a polyolefin microporous membrane, the polyolefin microporous membrane having a water permeation efficiency of 1.21 to 2.90 ml/min.Math.cm.sup.2, the polyolefin microporous membrane having a bubble point of 0.40 MPa to 0.65 MPa, the polyolefin microporous membrane having a compressibility of less than 15%.

The porous hollow fiber membrane of the present invention contains a thermoplastic resin, and includes a surface having a surface porosity of 32 to 60% and a fine pore diameter of 300 nm or less, and has a compressive strength of 0.7 MPa or more. The porous hollow fiber membrane of the present invention may include at least two layers, and in this case, the surface of one layer has a thickness of backbone of 0.3 to 20 μm and a fine pore diameter of 0.3 to 10 μm, and the surface of the other layer has a surface porosity of 32 to 60% and a fine pore diameter of 0.05 to 0.3 μm.

The present invention provides a strong polymer electrolyte membrane which can provide a water electrolyzer operable at low electrolysis voltage. The polymer electrolyte membrane of the present invention comprises a fluorinated polymer and a woven fabric, wherein the weight of the woven fabric is from 20 to 95 g/m.sup.2, and the warp and weft of the woven fabric independently have a denier of from 30 to 100.

Provided herein are methods and systems pertaining to sequencing units of analytes using nanopores. In general, arresting constructs are used to modify an analyte such that the modified analyte pauses in the opening of a nanopore. During such a pause, an ion current level is obtained that corresponds to a unit of the analyte. After altering the modified analyte such that the modified analyte advances through the opening, another arresting construct again pauses the analyte, allowing for a second ion current level to be obtained that represents a second unit of the analyte. This process may be repeated until each unit of the analyte is sequenced. Systems for performing such methods are also disclosed.