A user authentication service for a communication network authenticates local users before granting them access to personalized sets of network resources. An exemplary embodiment comprises forming an artificial barrier to water flow, wherein the artificial barrier is located at or above a hydrocarbon-water interface between a water-bearing formation zone and a hydrocarbon-bearing formation zone. Following completion of polymerization, the cyclic polymer detaches from the complex via an intramolecular chain transfer reaction and the catalytic complex is regenerated. At least one void opening on the upper surface extends into the ground engaging base in a direction towards the bottom surface. The bioactive composite is loaded with a pharmaceutical composition and releases a therapeutically effective amount of a pharmaceutical composition for periods of up the 28 days.