Abstract: An asymmetrical, microporous, hollow fiber membrane is made from a polymeric dope mixture of polysulfone and polyvinyl pyrrolidone dissolved in an aprotic solvent. The physical morphology of the hollow fiber membrane, i.e., the asymmetric microporous wall, is rapidly formed by passing the polymeric dope mixture through an outer annular orifice of a tube-in-orifice spinneret while simultaneously passing a precipitating solution through the central tube of the spinneret. The emerging hollow fiber travels substantially downward for about 0.01-10 m before submersion into a quenching bath. The asymmetrical, microporous, hollow fiber membrane is biocompatible and suitable for use in, for example, dialysis, hemodialysis, ultrafiltration, and water filtration applications.

Abstract: A portable tree stand assembly includes a horizontal platform, which is easily mountable to a trunk of a tree. A vertical mounting structure is connected to a rear side of the horizontal platform and extends vertically downward from the horizontal platform. A cantilevered support structure is connected between a front side of the horizontal platform and a base of the vertical mounting structure, which allows an upper surface of the horizontal platform to be unobstructed. A plurality of spurs protruding rearwardly from the vertical mounting structure grip the surface of a tree without causing substantial damage to the tree. A link chain secures the stand to the tree without requiring cinching or tightening.