Fabrication of Controlled Release Devices Using Supercritical Antisolvent Method

In this study, the supercritical antisolvent with enhanced mass transfer method (SASEM) is used to fabricate micro and nanoparticles of biocompatible and biodegradable polymer PLGA (poly DL lactide co glycolic acid). This process may be extended to the encapsulation of drugs in these micro and nanoparticles for controlled release purposes. Conventional supercritical antisolvent (SAS) process involves spraying a solution (organic solvent + dissolved polymer) into supercritical fluid (CO[subscript 2]), which acts as an antisolvent. The high rate of mass transfer between organic solvent and supercritical CO[subscript 2] results in supersaturation of the polymer in the spray droplet and precipitation of the polymer as micro or nanoparticles occurs. In the SASEM method, ultrasonic vibration is used to atomize the solution entering the high pressure with supercritical CO[subscript 2]. At the same time, the ultrasonic vibration generated turbulence in the high pressure vessel, leading to better mass transfer between the organic solvent and the supercritical CO₂. In this study, two organic solvents, acetone and dichloromethane (DCM) were used in the SASEM process. Phase Doppler Particle Analyzer (PDPA) was used to study the ultrasonic atomization of liquid using the ultrasonic probe for the SASEM process. Scanning Electron Microscopy (SEM) was used to study the size and morphology of the polymer particles collected at the end of the process.

Context Interchange as a Scalable Solution to Interoperating Amongst Heterogeneous Dynamic Services

Many online services access a large number of autonomous data sources and at the same time need to meet different user requirements. It is essential for these services to achieve semantic interoperability among these information exchange entities. In the presence of an increasing number of proprietary business processes, heterogeneous data standards, and diverse user requirements, it is critical that the services are implemented using adaptable, extensible, and scalable technology. The COntext INterchange (COIN) approach, inspired by similar goals of the Semantic Web, provides a robust solution. In this paper, we describe how COIN can be used to implement dynamic online services where semantic differences are reconciled on the fly. We show that COIN is flexible and scalable by comparing it with several conventional approaches. With a given ontology, the number of conversions in COIN is quadratic to the semantic aspect that has the largest number of distinctions. These semantic aspects are modeled as modifiers in a conceptual ontology; in most cases the number of conversions is linear with the number of modifiers, which is significantly smaller than traditional hard-wiring middleware approach where the number of conversion programs is quadratic to the number of sources and data receivers. In the example scenario in the paper, the COIN approach needs only 5 conversions to be defined while traditional approaches require 20,000 to 100 million. COIN achieves this scalability by automatically composing all the comprehensive conversions from a small number of declaratively defined sub-conversions.