Homotopy method for the eigenvalues of symmetric tridiagonal matrices

We will present the homotopy method for finding eigenvalues of symmetric, tridiagonal matrices. This method finds eigenvalues separately, which can be a large advantage on systems with parallel processors. We will introduce the method and establish some bounds that justify the use of Newton’s method in constructing the homotopy curves.     

Pyridine-Type Complexes of Transition-Metal Halides XIV. Part III. Complexes with 2,4-, 2,6-, 3,4- and 3,5-lutidines

Compounds obtained by a solid–gas phase reactions between copper(II) chloride and bromide and 2,4-, 2,6- 3,4- and 3,5-lutidines were studied using thermogravimetry, far-infrared, electronic spectroscopy and X-ray diffraction. The results were compared with the corresponding data for the similar compounds with methylpyridines and 2,4,6-collidine. A special attention was paid to the host-guest phenomenon, a new structural feature of transition-metal halide complexes. This revised version was published online in August 2006 with corrections to the Cover Date.     

Ion-pair solid-phase extraction

Solid-phase extraction (SPE) is a technique widely employed by analytical chemists. SPE cartridges are available in a wide variety of formats containing media with diverse chemistries. This paper will review ion-pair SPE, one of the less frequently applied, and presumably less well-known techniques. Advantages of this technique over more conventional reversed-phase or ion-exchange SPE include selectivity, compatibility with rapid evaporative concentration, and potential application to multiclass multiresidue analysis.     

The effect of elevated reactant temperatures on soot nanostructures in a coflow diffusion ethylene flame

The relationship between soot surface growth, soot nanostructure and reactant temperature (T_r) in a coflow diffusion ethylene flame was investigated with multiple experimental techniques. The T_r was raised by heating the coflow air. Three cases, with 300K, 473K, and 673K T_r, respectively, were studied. Laser-induced Incandescence revealed that increasing T_r promotes soot formation. Although soot primary particle diameter (d_p) also increases with T_r, the increase in d_p slows down after 473K T_r, suggesting that there is a deceleration in soot surface growth. Transmission Electron Microscopy (TEM) imaging showed that increased T_r promotes soot aggregation and yields larger and more mature primary particles. The assessment of the Selected Area Electron Diffraction (SAED) patterns indicated that, at 673K T_r, there is a growth of lattice planes. Raman spectroscopy revealed further structural details. By assessing the band intensity ratios, soot for the T_r of 673K has more curved nanostructures. The deceleration of soot surface growth may be explained by surface aging, which is characterized by an increase in curved nanostructures.