The effect of high magnetic fields on degenerate band excitons in InSb

A variational technique is used to calculated the binding energy of degenerate band excitons in InSb as a function of magnetic field. the nonparabolicity of the conduction bands is taken into account and standard perturbation theory is used for deviation of the valence bands from the spherical. A comparison of the theoretical results and available experimental results is made.     

Nonlinear matrix solution of the Kohn-Hohenberg-Sham equation for electrons in a jellium slab

A new method is presented for the numerical solution of the Kohn- Hohenberg-Sham equation for the one-electron wavefunctions and energies for electrons in the presence of a jellium slab of finite thickness.     

Construction of skew Room squares

It is shown that the question of existence of skew Room squares is solved in all but finitely many cases.     

Pseudoazulene. reaktionen von fulvenen mit 3,6-dicarbomethoxy-1,2,4,5-tetrazin

Fulvenes (1) react with 3,6-dicarbomethoxy-1,2,4,5-tetrazine (2) to give 4a,5-dihydro-2H-cyclopenta[d]pyridazines (3), which can be transformed with mangandioxide to the dehydrocompounds 4. Through 1,6-addition of hydrogen pseudoazaazulenes of the 2H-cyclopenta[d]pyridazin type (6) are obtained. Oxidative C-C-connection of these compounds yields dehydrodimers (10), which on hydrogenation give bis-pseudoazaazulenes (11).     

On one-factorizations of compositions of graphs

Let G[H] denote the composition of the graphs G and H. If G can be decomposed into one-factors and two-factors, H can be decomposed into one-factors, and H is not the empty graph on an odd number of vertices, then G[H] can be decomposed into one-factors.     

Incipient Nucleophilic Attack on a Carbonyl Group Adjacent to a Stereogenic Centre in Peri Naphthalene Derivatives

The crystal structures of four peri-naphthalene derivatives model the Felkin–Anh approach of a nucleophilic centre (OH or NMe₂) to a carbonyl group attached to a stereogenic centre bearing a large (phenyl), medium (methyl) and a small (hydrogen) group. Thus, the conformation about the (O=)C−C* bond directs the phenyl group approximately perpendicular to the carbonyl group and away from the nucleophile, whose line of approach lies close to the hydrogen atom attached to the stereogenic centre. The nucleophile approaches the carbonyl group at 102.99(11)-112.34(9)° (for NMe₂) and at 118.56(14)° (for OH). The small pyramidalization of the carbonyl carbon towards the nucleophile increases as the nucleophilic centre approaches closer.     

Metal catalyzed rearrangement of a 2,2'-bipyridine Schiff-base ligand to a quaterpyridine-type complex

A Co(II) quaterpyridine-type complex has been prepared via a one-pot transformation of a 2,2'-bipyridine Schiff-base ligand in the presence of a Lewis acidic metal salt.     

Assessment of heavy metals emission from traffic on road surfaces

This study aims to analyse RDS heavy metal concentrations on road deposited sediment (RDS) using Riccarton Campus of Heriot-Watt University, Edinburgh, Scotland as a study site. RDS samples were collected at two transverse positions from different sites over a 4 month period in order to describe the influence of traffic on heavy metal emissions. The heavy metal concentrations of the RDS were determined by strong nitric acid digestion and atomic absorption spectrometry. The mean concentrations for Zn, Cu, Cd, Cr, Ni, Pb and Fe were found to be 213, 57, 1, 16, 15, 118, and 13497 mg kg-1 from samples near to the curb and 211, 79, 2, 15, 9, 35, and 14276 mg kg⁻¹ from samples 1 m from the curb respectively. Furthermore for both positions the highest concentrations for all metals were associated with the finer fraction (<63 μm) and stronger correlations between the metals were found further from the curb than near the curb, indicating that metals accumulating on the road surface further from the curb may likely be from the same source (traffic), while the sources of metals near the curb are more diverse.