A disposable absorbent article adapted to be worn about a lower torso of a human body and having a chassis, a non-removable absorbent core component disposed in a crotch region of the chassis, and one or more replaceable absorbent core component or components disposed in capillary liquid communication with the non-removable absorbent core component. Responsive to the monitored waves, an attribute of the fluid is estimated, including a sonic velocity, a mixture of gas and oil, a mixture of water and oil, an amount of sand, an amount of gas, an amount of skin effect, or a depth of fluid. , in a store, chain or other retail enterprise. In a further embodiment, an electrode can be formed from a portion of a substrate or well region, and the other electrode can be formed over such portion of the substrate or well region. The present invention relates to a method of micronizing the above compound characterized in that the compound is comminuted, for example, to the extent that the mean particle diameter of the compound will be 1\u02dc25 \u03bcm with 50 \u03bcm and larger particles accounting for 2% or less with a mill of the open-circuit pulverizing type.