Diffusion Synthetic Method Research Articles

Diffusion synthetic methods for computational modeling of one-speed slab-geometry transport problems with linearly anisotropic scattering

Two diffusion synthetic methods are described for computational modeling of one-speed, slab-geometry transport problems with linearly anisotropic scattering. These methods are referred to as diffusion synthetic methods, since the lower-order diffusion is used to simplify numerical solutions to the higher-order transport equation. In part I of this paper the word simplify is used in the sense of reducing the number of iterations to a prescribed stopping criterion; in other words, in the sense of accelerating the iteration on the scattering source in discrete ordinates (SN) calculations, by generating an improved initial guess. In part II, the word simplify is used in the sense of generating numerical results for the angular flux by solving analytically the first-order form of the transport equation in slab geometry with diffusion approximation for the scattering source integral terms. As with these two offered synthetic methods, special approximate boundary conditions are used in the diffusion equation to account for prescribed incident flux on the outer boundaries of the slab, including vacuum boundary conditions. Numerical results are given to illustrate the application of these two synthetic methods.

Radius-dependent assembly of complexes with the rigid unsymmetric ligand 5-(2-pyridyl)-1,3,4-oxadiazole-2-thione: Syntheses, structures and luminescence properties

The free ligand, 5-(2-pyridyl)-1,3,4-oxadiazole-2-thione ( 1, HL5), has been synthesized and characterized; its three new functional d 10 transition-metal complexes, [Zn( L5) 2(H 2O) 2] ( 2), [Cd( L5) 2] n ( 3) and [Hg 2( L5) 4] ( 4), have been successfully obtained by a diffusion synthetic method and characterized by single-crystal X-ray diffraction, infrared spectroscopy, elemental analysis, thermogravimetric analysis, and photoluminescence. On the basis of the X-ray analyses, the radii of the metal ions are found to play an important role in determining the structures. The radii and nature of the metal ions can impart their influence on the coordination geometry of the d 10 transition-metal atoms, which seems to be the main factor controlling the structures and luminescent properties of the reaction products in this system.