Methods and structures for constructing a magnetic core of a coupled inductor. The operation begins by computing a concept score for a first concept in a first case received by the deep question answering system, the concept score being based on a machine learning concept model for the first concept. X may be a sulfonyl, phosphoryl, or 1,3,5-triazinyl group, Y may be a halogen leaving group, N may be a basic nucleophilic group, S may be an organic group, and ZM may be an ionizable end group. In order to provide a cleaning action, the contact surface is configured to progressively contact the face during sealing engagement and peel away from the face during disengagement.