The Grid approach provides the ability to access and use distributed resources as part of virtual organizations. The emerging Grid infrastructure gives rise to a class of scientific applications and services to support collaborative and distributed resource-sharing requirements as part of teleimmersion, visualization, and simulation services. Because such applications operate in a collaborative mode, data must be stored and delivered in timely manner to meet deadlines. Hence, this class of applications has stringent real-time constraints and quality-of-service (QoS) requirements. A QoS management approach is required to orchestrate and guarantee the interaction between such applications and services. In this paper we discuss the design and prototype implementation of a QoS system and show how we enable Grid applications to become QoS compliant. We validate this approach through a case study of nanomaterials. Our approach enhances the current Open Grid Services Architecture. We demonstrate the usefulness of the approach on a nanomaterials application.