The present invention relates to a dialysate regeneration method that reduces a urea concentration of a urea-containing aqueous solution, the method including a reverse osmosis process of obtaining, from the urea-containing aqueous solution, a concentrate having a higher urea concentration and a permeate having a lower urea concentration by using a reverse osmosis membrane element at an operating pressure of 0.5 MPa or more and 2.0 MPa or less, in which the urea concentration of the urea-containing aqueous solution is 0.5 g/L or more, the reverse osmosis membrane element includes a reverse osmosis membrane, and the reverse osmosis membrane has a pore diameter of 7.0 Å or less as measured by a positron annihilation lifetime measurement method.

An array of discrete nanofiber films that are physically separated from one another are described. Techniques for forming the nanofiber film array are also described. Techniques for forming these structures include placing a suspension of nanofibers and/or nanoparticles on a patterned substrate. A pressure differential is applied, drawing the solvent of the suspension through holes in a mask. The nanofibers collect on an impermeable layer on the mask in a pattern corresponding to the negative features (grooves, holes, trenches) of the mask as the solvent is flowed through the holes.

Porous membranes are provided according to the invention having desirable coefficient of thermal expansion and large surface area, for example at least about 4,000 mm.sup.2. These porous membranes may be made according to an exemplary process employing lithographic patterning of a photoresist followed by development of the photoresist and etching. In one aspect, the etch barrier layer is chosen from a material that does not react with or incorporate metal or other contaminants into the membrane layer.

Embodiments of the present invention provide the integration of the function of the feed spacer, the permeate carrier, or both, as a part of the membrane sheet in a spiral wound membrane element.

An evaporative cooling system includes a porous ceramic body with a plurality of dry channels and a plurality of wet channels. The plurality of dry channels are configured to inhibit transfer of water vapor into the dry channels and include a barrier layer that includes a roughened layer with a features size less than 1000 nm and a hydrophobic chemical modification disposed on the roughened layer. The plurality of wet channels are configured to allow transfer of water vapor.

A biocompatible polymeric membrane includes pores defined between two material layers, where the first membrane material layer includes strips, and the second membrane material binds to each of the plurality of first membrane material layer strips includes a plurality of windows exposing each of the first membrane material strips. The biocompatible polymeric filtration membrane comprises pores defined by uniform passages defined by the first membrane material layer strips and the second membrane material layer within each window.

A fluid conduit includes a first portion having a first porosity, a second portion disposed immediately adjacent to the first portion, the second portion having a second porosity that is greater than the first porosity, and a third portion of the fluid conduit disposed immediately adjacent to the second portion, the third portion having a third porosity that is less than the second porosity. Each of the first portion, the second portion, and the third portion may be integrally formed as a single, continuous piece defining the fluid conduit.

An evaporative cooling system includes a porous ceramic body with a plurality of dry channels and a plurality of wet channels. The plurality of dry channels are configured to inhibit transfer of water vapor into the dry channels and include a barrier layer that includes a roughened layer with a features size less than 1000 nm and a hydrophobic chemical modification disposed on the roughened layer. The plurality of wet channels are configured to allow transfer of water vapor.

Porous membranes are provided according to the invention having desirable coefficient of thermal expansion and large surface area, for example at least about 4,000 mm.sup.2. These porous membranes may be made according to an exemplary process employing lithographic patterning of a photoresist followed by development of the photoresist and etching. In one aspect, the etch barrier layer is chosen from a material that does not react with or incorporate metal or other contaminants into the membrane layer.

Porous membranes are provided according to the invention having desirable coefficient of thermal expansion and large surface area, for example at least about 4,000 mm.sup.2. These porous membranes may be made according to an exemplary process employing lithographic patterning of a photoresist followed by development of the photoresist and etching. In one aspect, the etch barrier layer is chosen from a material that does not react with or incorporate metal or other contaminants into the membrane layer.