In one aspect, the invention relates to a method for \u201ctagging\u201d proppants so that they can be tracked and monitored in a downhole environment, based on the use of composite proppant compositions containing dispersed fillers whose electromagnetic properties change at a detectable level under a mechanical stress such as the closure stress of a fracture. In one aspect, the invention provides a method for processing a substrate including depositing a nitrogen containing barrier layer on a substrate surface and then depositing a nitrogen free barrier layer thereon. The ends have inner sides that generally face one another across the test zone, and outer sides that are generally opposed to one another and the test zone. The inboard mount is an elongated bar extending beyond the height of the ROS unit. Finally, the method involves providing a representation of the first determination result and a representation of the second determination result.