A filter medium includes first and second porous films mainly containing fluororesin, and a pre-collection member upstream of the first film. The second film is downstream of the first film. The pre-collection member has a pressure drop when air is passed through at a flow rate of 5.3 cm/s of between 15 Pa and 55 Pa, a collection efficiency of NaCl particles having a particle diameter of 0.3 ?m when air containing the particles is passed hrough at a flow rate of 5.3 cm/s of between 25% and 80%, a thickness of 0.4 mm or less, and a PF value between 7 and 15. The PF value={?log((100?collection efficiency (%))/100)}/(pressure drop (Pa)/1000). A ratio of the PF value of the pre-collection member to the PF value when the first and second films are overlapped, is between 0.20 and 0.45. The filter medium can be used in a filter pack or filter unit, and may be produced by integrating the first and second films and the pre-collection member using heat lamination.

A porous membrane for use in an electroosmotic pump for pumping a fluid by electroosmotic transport, the porous membrane comprising: first and second opposite surfaces and a net fluid flow direction extending in the porous membrane between said opposite surfaces, wherein when a given amount of charge flows through the porous membrane from the first to the second opposite surface more electroosmotic transport of the fluid will occur than when the same amount of charge flows through the porous membrane from the second to the first, opposite surface.

The problem addressed by the present invention is to provide a separation membrane with superior permeation performance and separation performance and having few occurrences of defects. The present invention relates to a separation membrane wherein: the separation membrane has a layer (I) with a thickness of 0.5-100 ?m; letting, in a cross-section in the direction of thickness of the layer (I), region a be a region with a depth of 50-150 nm from a surface (surface A), region b a region with a depth of 50-150 nm from the other surface (surface B), and region c a region with a thickness of 100 nm where the depth from both surfaces is the same, the average pore diameter Pa for region a and the average pore diameter Pb for region b are both 0.3-3.0 nm and the average pore diameter Pc for region c is 3.0 nm or less; and the percentage of open area Ha for region a, the percentage of open area Hb for region b, and the percentage of open area Hc for region c satisfy the following equations. 2Hc<Ha 2Hc<Hb

Described herein are filtration membranes and related, compositions, methods and systems and in particular filtration membranes with embedded polymeric micro/nanoparticles and related compositions, methods, and systems.

The present invention relates to: an alumina powder wherein a ratio (TBD/LBD) of a tapped bulk density (TBD) to a loose bulk density (LBD) is 1.5 or more; an alumina slurry containing the same; an alumina-containing coating layer; a multilayer separation membrane; and a secondary battery.

Micro- and nanofilters with precision pore sizes and pore layout have applications in many fields including capturing circulating tumor cells and fetal cells in blood, water treatment, pathogen detection in water, etc. Methods to fabricate micro- and nanofilters not using track etching or reactive ion etching are provided, allowing easy fabrication of single layer or stack of films simultaneously, and/or stack of films on rolls. Microfilter can be made using one or more layers of material. Invention enables mass production of microfilters with lithographic quality at low cost. Isolation, enumeration and characterization of circulating tumor cells using microfilters provides (i) guides to cancer treatment selection and personalize dosage, (ii) low cost monitoring for treatment response, disease progression and recurrence, (iii) assessment of pharmacodynamic effects, (iv) information on mechanisms of resistance to therapy, and (v) cancer staging. Microfabrication methods are also applicable to fabrication of any free standing patterned polymeric films.

The present invention relates to a layered semipermeable membrane satisfying the conditions below. (A) The maximum peak intensity between 3700 and 2900 cm.sup.?1 is 0.08 or greater in the difference spectrum between an IR spectrum measured at 25? C. and 97% relative humidity and an IR spectrum measured at 25? C. and 3% relative humidity. (B) The peak top wavenumber between 3700 and 2900 cm.sup.?1 of the aforementioned difference spectrum is 3400 cm.sup.?1 to 3550 cm.sup.?1. (C) The N1s peak has a maximum value at 401 eV or greater in X-ray photoelectron spectroscopy in which X-rays are radiated to a coat layer.

A method for manufacturing an ion exchange membrane is provided. The method for manufacturing an ion exchange membrane, according to one embodiment of the present invention, comprises the step of electrospinning a support fiber producing solution and an ion exchange fiber producing solution respectively to prepare a laminate in which a support fiber mat consisting of a support fiber and an ion exchange fiber mat consisting of an ion exchange fiber are alternatively laminated. According to the present invention, it is possible to simply control factors, such as the thickness, electroconductivity and mechanical strength of the membrane, and the diameter/ratio of a pore, etc. to be suitable for the use of ion exchange membrane during the manufacturing process, to simplify the manufacturing process. As such, the ion exchange membrane manufactured by the method can be utilized as a universal ion exchange membrane which has a large ion exchange capacity, a small electrical resistance, and a small diffusion coefficient as well as excellent mechanical strength and durability.

Provided is a method for producing a porous polyimide film with which it is possible to suppress the occurrence of curling in the polyimide-fine particle composite film obtained by firing the unfired composite film. The method for producing a porous polyimide film of the present invention includes, in the following order: forming an unfired composite film using a varnish that contains a resin including polyamide acid and/or polyimide, fine particles, and a solvent; immersing the unfired composite film in a solvent including water; firing the unfired composite film to obtain a polyimide-fine particle composite film; and removing the fine particles from the polyimide-fine particle composite film.

The present invention aims to provide a gas-selective permeable membrane that has gas permeability and gas selectivity capable of highly separating a target gas from other gases, is less likely to be influenced by the temperature condition employed, and is excellent in strength and handleability. The invention uses at least one or more polymerizable compounds to provide a gas-selective permeable film that contains a polymer having an optically uniaxial or multiaxial molecular alignment and to provide a laminate including a gas-permeable substrate and the permeable membrane laminated thereon.