Spinor model of a perfect fluid and their applications in Bianchi type-I and FRW models

Different characteristic of matter influencing the evolution of the Universe has been simulated by means of a nonlinear spinor field. Exploiting the spinor description of perfect fluid and dark energy evolution of the Universe given by an anisotropic Bianchi type-I (BI) or isotropic Friedmann-Robertson-Walker (FRW) one has been studied.Comment: 10 pages, 8 Figure

Ion-Assisted Pulsed Laser Deposition of Amorphous Tetrahedral-Coordinated Carbon Films

AbstractA parametric study has been performed of amorphous tetrahedral carbon (a-tC) films produced by ion- assisted pulsed laser deposition (IAPLD). The ion voltage, current density, and feed gas composition (nitrogen in argon) have been varied. The resultant films were characterized by thickness, residual stress, Raman spectroscopy, and electrical resistivity. The Raman spectra have been fit to two gaussian peaks, the so called graphitic (“G”) peak and the disorder (“D”) peak. It has been found that the magnitude of the D peak and the residual compressive stress are inversely correlated. At low beam voltages and currents, the magnitude of the D peak is low, increasing as the ion beam voltage and current are raised. The ion beam voltage has the most dramatic effect on the magnitude of the D peak. At low voltages (200–500 V) the magnitude of the D peak is greater for ion beams with high percentages of nitrogen possibly indicative of C-N bonding in the films. At higher voltages (500 - 1500V) the D peak intensity is less sensitive to the nitrogen content of the beam.</jats:p