Economic Growth and Development in South Asia, with and without Regional Cooperation

Economic Development, Economic Growth, South Asia

Study of Staebler-Wronsky degradation effect in a Si:H based P-I-N solar cells

The objective of this study is to improve the stability and efficiency of thin solar cells with emphasis on a-Si:H devices. The research project was broken down into three main phases. The first involves designing and building a UHV glow discharge system; the second involves making good quality films and eventually efficient cells; the final phase will be analytical

Materials Selection and Processing Techniques for Small Spacecraft Solar Cell Arrays

Body mounted germanium substrate solar cell arrays form the faces of many small satellite designs to provide the primary power source on orbit. High efficiency solar cells are made affordable for university satellite programs as triangular devices trimmed from wafer scale solar cells. The smaller cells allow array designs to pack tightly around antenna mounts and payload instruments, giving the board design flexibility. One objective of this work is to investigate the reliability of solar cells attached to FR-4 printed circuit boards. FR-4 circuit boards have significantly higher thermal expansion coefficients and lower thermal conductivities than germanium. This thermal expansion coefficient mismatch between the FR-4 board and the components causes concern for the power system in terms of failures seen by the solar cells. These failures are most likely to occur with a longer orbital lifetime and an extended exposure to harsh environments. This work compares various methods of attaching solar cells to printed circuit boards, using solder paste alone and with a silicone adhesive, and considering the application of these adhesives by comparing the solder joints when printed by screen versus a stencil. An environmental test plan was used to compare the survivability and performance of the solar arrays

Increased platelet reactivity in idiopathic pulmonary fibrosis is mediated by a plasma factor

Introduction Idiopathic Pulmonary Fibrosis (IPF) is a progressive, incurable fibrotic interstitial lung disease with a prognosis worse than many cancers. Its pathogenesis is poorly understood. Activated platelets can release pro-fibrotic mediators that have the potential to contribute to lung fibrosis. We determine platelet reactivity in subjects with IPF compared to age-matched controls. Methods Whole blood flow cytometry was used to measure platelet-monocyte aggregate formation, platelet P-selectin expression and platelet fibrinogen binding at basal levels and following stimulation with platelet agonists. A plasma swap approach was used to assess the effect of IPF plasma on control platelets. Results Subjects with IPF showed greater platelet reactivity than controls. Platelet P-selectin expression was significantly greater in IPF patients than controls following stimulation with 0.1 µM ADP (1.9% positive ±0.5 (mean ± SEM) versus 0.7%±0.1; p = 0.03), 1 µM ADP (9.8%±1.3 versus 3.3%±0.8; p<0.01) and 10 µM ADP (41.3%±4.2 versus 22.5%±2.6; p<0.01). Platelet fibrinogen binding was also increased, and platelet activation resulted in increased platelet-monocyte aggregate formation in IPF patients. Re-suspension of control platelets in plasma taken from subjects with IPF resulted in increased platelet activation compared to control plasma. Conclusions IPF patients exhibit increased platelet reactivity compared with controls. This hyperactivity may result from the plasma environment since control platelets exhibit increased activation when exposed to IPF plasma

Description of Liquid Nitrogen Experimental Test Facility

The Liquid Nitrogen Test Facility is a unique test facility for ground-based liquid nitrogen experimentation. The test rig consists of an insulated tank of approximately 12.5 cubic ft in volume, which is supplied with liquid nitrogen from a 300 gal dewar via a vacuum jacketed piping system. The test tank is fitted with pressure and temperature measuring instrumentation, and with two view ports which allow visual observation of test conditions. To demonstrate the capabilities of the facility, the initial test program is briefly described. The objective of the test program is to measure the condensation rate by injecting liquid nitrogen as a subcooled spray into the ullage of a tank 50 percent full of liquid nitrogen at saturated conditions. The condensation rate of the nitrogen vapor on the subcooled spray can be analytically modeled, and results validated and corrected by experimentally measuring the vapor condensation on liquid sprays

Stabilizing intrinsic defects in SnO2_{2}

TThe magnetism and electronic structure of Li-doped SnO$_{2}$ are investigated using first-principles LDA/LDA$+U$ calculations. We find that Li induces magnetism in SnO$_{2}$ when doped at the Sn site but becomes non-magnetic when doped at the O and interstitial sites. The calculated formation energies show that Li prefers the Sn site as compared with the O site, in agreement with previous experimental works. The interaction of Li with native defects (Sn V$_\mathrm{Sn}$ and O V$_\mathrm{O}$ vacancies) is also studied, and we find that Li not only behaves as a spin polarizer, but also a vacancy stabilizer, i.e. Li significantly reduces the defect formation energies of the native defects and helps the stabilization of magnetic oxygen vacancies. The electronic densities of states reveals that these systems, where the Fermi level touches the conduction (valence) band, are non-magnetic (magnetic).cancies. The electronic densities of states reveal that those systems, where the Fermi levels touch the conduction (valence) band, are non-magnetic (magnetic).Comment: Phys. Rev. B (2013), Accepte