Advanced microfabrication technologies for microspacecraft

Advanced microfabrication technologies offer the prospect of reducing the weight and size of spacecraft through the use of lighter and stronger materials in conjunction with new mechanical/structural design concepts and design optimization methods. At the same time, electronic components have been scaled down while increasing functional utility. A two-fold benefit is derived for space applications through the use of less expensive components and the lower launch costs associated with lighter components. GE-CRD is actively pursuing research in these key technologies for a wide range of applications including satellites. These key technologies will be reviewed and an update on GE progress will be given. The need to reduce weight and lower cost, while maintaining product quality and reliability are primary drivers in the design of satellites, in general, and microsatellites in particular. For the structural subsystem, these requirements pose a complex design problem unless new mechanical design concepts and computer-aided design optimization methods are employed. Several new concepts, such as battery packs doubling as panel reinforcements and fuel tanks as integral structural members, need to utilized. In addition, new viscoelastic material damping concepts for spacecraft components provide for lighter weight/lower cost designs, while satisfying the structural dynamics requirements. High density interconnect (HDI) technology permits the use of bare IC's on a ceramic substrate with 90 percent active area utilization. A copper/polyimide multilayer structure is the backbone of the technology, which has demonstrated a size/weight reduction of greater than 10x compared to printed circuit board with performance up to the GHz level. HDI modules have exceptional mechanical robustness as evidenced by survival of 180 kg rapid acceleration tests. Microelectromechanical systems (MEMS) are redefining sensors and actuators by miniaturization through micromachining techniques. Sharing many fabrication steps with HDI, we have developed a new technique for surface micromachining of copper/polyimide structures using computer-aided laser patterning

Evaluation of Antioxidant and Antimicrobial Activities of Chitrakadi Vati, a Ayurvedic Formulation

Abstract Free radicals are implicated for more than eighty diseases including diabetes mellitus, arthritis, cancer, ageing, etc. in treatment of theses diseases; antioxidant therapy has gained an utmost importance. Current research is now directed towards finding naturally occurring antioxidant of herbal drugs. Antioxidant activity of methanol extract of Chitrakadi Vati was evaluated by using Phosphomolybdenum assay, DPPH radical scavenging assay, superoxide radical scavenging assay and ABTS assay. The total phenolic, total tannins and total flavonoids content were determined. Antibacterial activity was also studied against Bacillus subtilis, Escherichia coli, Staphylococcus aureus and Streptococcus pyogenes by using cup-plate method. Erythromycin was used as standard antibacterial agent. The methanol extract was diluted into different concentration (1, 2, 4, 6, 8, 10 mg/l00 µl) with DMSO. The results of the study revealed that, the Chitrakadi Vati exhibited significant antibacterial activity