In one aspect, the invention is directed to a method for determining the concentration of anionic polymers or oligomers in industrial water comprising combining a buffer solution and a cationic dye solution, measuring absorbance of the buffer-dye admixture at selected wavelength and determining the polymer or oligomer concentration from the previously determined absorbance values. Control over the porosity is provided by using webs that exhibit a narrow, unimodal distribution of fiber diameters over the bulk of its distribution, such as in the top 80%. In another embodiment, the second material is formed into a second layer. 78 \u03bcgml, while showing weak or no cytotoxicity to mammalian cells. By defining a dynamic composition sensitivity, the CG phase correction method can be conveniently incorporated with SENSE reconstruction for the application of multi-shot SENSE DWI. 8, and a molar ratio of F to Cl is about 0.