Disclosed are porous elements that include sintered polymeric particles. The polymeric particles can be formed of a thermoplastic composition that includes a polyarylene sulfide. The polymeric particles sintered to form the porous elements have a very narrow size distribution. The porous elements can maintain their functionality and morphology even when utilized in high temperature applications.

An exhaust gas purification filter includes a plurality of cells extending in a filter axial direction, a porous partition separating and defining the plurality of cells, and a sealing section sealing the plurality of cells alternately at both filter ends. In the exhaust gas purification filter, the partition has a void volume of a reduced dale, Vvv, and a material volume of a reduced peak, Vmp, as volume parameters determined in noncontact surface roughness measurement on a surface of the partition, with their total value being 1.8 μm.sup.3/μm.sup.2 or less.

Intra-nasal filter devices and methods for their manufacture and use are disclosed. An intra-nasal filter device includes: a first stage filter proximate the septum; and a second stage filter comprising a flexible material extending upwardly from the first filter stage filter; wherein the flexible material comprises: an impedance in the range of 0.02 to 0.2 cmH.sub.2O; an effective cross-sectional area in the range of 0.2 to 2 square inches; and a plurality of radially extending geometric structures disposed along an axial length of the second stage.

An exhaust gas purification filter includes a plurality of cells each extending from an inflow end face to an outflow end face, a porous partition wall forming the cells in a partitioned manner, inflow-side sealing parts sealing openings on an inflow end face side of outflow cells where the exhaust gas flows out, and outflow-side sealing parts sealing openings on an outflow end face side of inflow cells where the exhaust gas flows in. Each of the inflow-side sealing parts has a porosity of less than 60%. The partition wall has a porosity of 60% or more and 70% or less. Assuming a pore size, at which cumulative pore volume is 50% in pore size distribution of the inflow-side sealing parts, is d50.sub.Pin, and a pore size, at which cumulative pore volume is 50% in pore size distribution of the partition wall, is d50.sub.B, the pore size d50.sub.Pin is less than 18 μm, and the pore size d50.sub.B is 18 μm or more and 25 μm or less.

A pillar-shaped honeycomb structure including an outer peripheral side wall, a plurality of first cells provided on an inner peripheral side of the outer peripheral side wall, the first cells extending from a first end surface to a second end surface, each opening on the first end surface and having a sealing portion with an average void ratio of 4% or less on the second end surface, and a plurality of second cells provided on the inner peripheral side of the outer peripheral side wall, the second cells extending from the first end surface to the second end surface, each having a sealing portion with an average void ratio of 4% or less on the first end surface and opening on the second end surface, the first cells and the second cells being alternately arranged adjacent to each other with a partition wall interposed therebetween.

A filter media comprises a first fiber layer and a second fiber layer positioned downstream of the first fiber layer. The first fiber layer has a first geometric mean fiber diameter of less than 1 pm such that the geometric standard deviation of fiber diameter is greater than 2. The second fiber layer has a second geometric mean fiber diameter of less than 1 pm such that the geometric standard deviation of fiber diameter is less than 2.

A manufacturing method of a honeycomb filter includes a kneaded material preparation process, a forming process, and a firing process, wherein the cordierite forming raw material contains porous silica as an inorganic pore former, in a cumulative particle size distribution of the cordierite forming raw material, particle diameters (μm) of 10% by volume, 50% by volume, and 90% by volume of the total volume from a small diameter side, are denoted by D.sub.(a) 10, D.sub.(a) 50 and D.sub.(a) 90, respectively, and a particle diameter (μm) of 50% by volume of the total volume from the small diameter side is denoted by D.sub.(b) 50 in a cumulative particle size distribution of the organic pore former, and the cordierite forming raw material and the organic pore former satisfy given expressions.

A manufacturing method of a honeycomb filter includes a kneaded material preparation process, a forming process and a firing process, wherein the cordierite forming raw material contains at least one of porous silica and fused silica, particle diameters (μm) of 10% by volume, 50% by volume and 90% by volume, from a small diameter side, are denoted by D.sub.(a) 10, D.sub.(a) 50 and D.sub.(a) 90 in a cumulative particle size distribution of the cordierite forming raw material, and a particle diameter (μm) of 50% by volume from a small diameter side is denoted by D.sub.(b) 50 in a cumulative particle size distribution of the organic pore former, D.sub.(b) 50 is 40 μm or less, and a cordierite forming raw material and an organic pore former satisfy given expressions.

Intra-nasal filter devices and methods for their manufacture and use are disclosed. An intra-nasal filter device includes: a first stage filter proximate the septum; and a second stage filter comprising a flexible material extending upwardly from the first filter stage filter; wherein the flexible material comprises: an impedance in the range of 0.02 to 0.2 cmH.sub.2O; an effective cross-sectional area in the range of 0.2 to 2 square inches; and a plurality of radially extending geometric structures disposed along an axial length of the second stage.

A nonwoven fabric according to the present invention is formed so that constituent fibers of the nonwoven fabric have an average fiber diameter of less than 1 μm and the number of fibers having fiber diameters ranging from 2 times up to 10 times the average fiber diameter of the constituent fibers is in a range of 2 to 20% of a total number of the constituent fibers. When the nonwoven fabric according to the present invention is used as a filter layer constituting an air filter, for example, it is possible to achieve high collection efficiency while reducing clogging (packing) between fibers to solve problems that may occur in using the conventional nanofiber nonwoven fabric (such as an increase in pressure loss and a decrease in service life).