Photonic band structures of ZnX (X = S, Se, Te)

Dielectric photonic band gap materials have received broad attention due to their distinguished performance in optical devices, microwave generation and laser acceleration. We have theoretically studied photonic band structure parameters of ZnX (X = S, Se, Te). The photonic band structure calculations are performed using the MIT photonic-bands package (MPB) to calculate eigenmodes frequency domain of Maxwell's equations with periodic boundary conditions. Eigenmodes are calculated in Fourier domain. Model calculations are based on two-dimensional periodic crystal structure. The lattices consist of cylindrical rods and gaps between the rods filled with air. Single-site zinc blende lattices are considered. In order to get "gap maps" we have calculated the gaps as a function of radius of the rods. Moreover we have calculated the nature of guided modes in line defect waveguide. Our results are in good agreement with those in the literature

Generalized Beddington model with the host subject to the Allee Effect

We investigate the stability and invariant manifolds of generalized Beddington model with the host population subject to the Allee effect.We obtain the condition for the existence of the fixed points and investigate the stability of the system

Nitridation of Nb surface by nanosecond and femtosecond laser pulses

Niobium nitride samples were prepared by laser nitridation in a reactive nitrogen gas environment at room temperature using a Q-switched Nd:YAG nanosecond laser and a Ti:sapphire femtosecond laser. The effects of laser fluence on the formed phase, surface morphology, and electronic properties of the NbNxwere investigated. The samples were prepared at different nanosecond laser fluences up to 5.0 ± 0.8 J/cm2at fixed nitrogen pressure of ~2.7 × 104Pa formed NbNxwith mainly the cubic ?-NbN phase. Femtosecond laser nitrided samples were prepared using laser fluences up to 1.3 ± 0.3 mJ/cm2at ~4.0 × 104Pa nitrogen pressure. Laser induced ripple patterns oriented parallel to the beam polarization were formed with spacing that increases with the laser fluence. To achieve a laser-nitrided surface with desired crystal orientation the laser fulence is an important parameter that needs to be properly adjusted. © 2014 Elsevier B.V. All rights reserved.U.S. Department of Energy United States-Israel Binational Science Foundation: 1228228, 0821180 Basic Energy Sciences Office of ScienceThis work was partially supported by the National Science Foundation - United States Grant Nos. 0821180 and 1228228 . A.H.F. Was supported by a Jefferson Lab scholarship. The authors are grateful to the Stanford Synchrotron Radiation Lightsource (SSRL), California, USA, for providing synchrotron-based XAS facility. Use of the Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-76SF00515 . Support of DOE Cooperative Research Program for SESAME project is acknowledged by A.H.F, O.M.O and Y.U

Applications of Graph Coloring

International Conference on Computational Science and Its Applications - ICCSA 2005; 9 May 2005 through 12 May 2005A graph G is a mathematical structure consisting of two sets V(G) (vertices of G) and E(G) (edges of G). Proper coloring of a graph is an assignment of colors either to the vertices of the graphs, or to the edges, in such a way that adjacent vertices / edges are colored differently. This paper discusses coloring and operations on graphs with Mathematica and webMathematica. We consider many classes of graphs to color with applications. We draw any graph and also try to show whether it has an Eulerian and Hamiltonian cycles by using our package Color

X-ray absorption spectroscopy measurements of liquid water

PubMedID: 16852732Recent studies, based on X-ray absorption spectroscopy (XAS) and X-ray Raman scattering (XRS), have shown that the hydrogen bond network in liquid water consists mainly of water molecules with only two strong hydrogen bonds. Since this result is controversial, it is important to demonstrate the reliability of the experimental data, which is the purpose of this paper. Here we compare X-ray absorption spectra of liquid water recorded with five very different techniques sensitive to the local environment of the absorbing molecule. Overall, the spectra obtained with photon detection show a very close similarity and even the observable minor differences can be understood. The comparison demonstrates that XAS and XRS can indeed be applied reliably to study the local bonding of the water molecule and thus to reveal the hydrogen bond situation in bulk water. © 2005 American Chemical Society