Thermodynamic modeling of Fe–Ni pentlandite

Gibbs energy modeling of iron–nickel pentlandite has been performed using experimental data of ternary phase equilibria. A three-sublattice approach in the framework of the Compound Energy Formalism is developed to refine a two-sublattice model of pentlandite recently applied within a complete assessment of the Fe–Ni–S system. Experimental data about the iron site fraction on the octahedral sublattice at 523.15 K for the composition Fe₅Ni₄S₈ as well as the enthalpy of formation at 298.15 K for the composition Fe_4.5Ni_4.5S₈ are predicted satisfactorily by the novel model. New possibilities to interpret experimental phase equilibrium data on complex phase relations with pentlandite are discussed together on the basis of the recent extension of a second high-temperature heazlewoodite phase to a ternary solution phase.     

Über einige Umsetzungen von 2,5-Diamino- sowie 2-Amino-1,3,4-thiadiazolen mit α-Halogenketonen zu Imidazo[2,1-b]-1,3,4-thiadiazolen

2,5-Diamino-1,3,4-thiadiazole (1) reacts with -halogencarbonyl compounds to 2-imino-3-phenacyl(acetonyl)-5-amino-1,3,4-thiadiazolines (3) which easily can be cyclised to 2-amino-6-aryl (alkyl)-imidazo[2,1-b]-1,3,4-thiadiazoles (4), the structure of which was proofed.On the basis of the amino function in position 2 these substances were able to form easilySchiff bases (5, 6, 7). Their semicyclic amidine system did not allow as yet to integraet it in a third ring system.

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8. Mitt. über Heterocyclen; 7. Mitt.:A. Sitte, R. Wessel undH. Paul, Mh. Chem.106, 1291 (1975).     

Application of ligand-exchange capillary electrophoresis to the chiral separation of alpha-hydroxy acids and beta-blockers

The application of the principle of ligand-exchange capillary electrophoresis to two substance classes is described. As chiral selector N-(2-hydroxyoctyl)-L-4-hydroxyproline-copper(II) complex was used. This principle was applied to the chiral separation of alpha-hydroxy acids and drugs containing amino alcohol structure such as beta-blockers. The enantioselectivity was found to be strongly dependent on pH corresponding to the optimal conditions for complex formation for each structure class.     

A-Priori Validation of Scalar Dissipation Rate Models for Turbulent Non-Premixed Flames

The modelling of scalar dissipation rate in conditional methods for large-eddy simulations is investigated based on a priori direct numerical simulation analysis using a dataset representing an igniting non-premixed planar jet flame. The main objective is to provide a comprehensive assessment of models typically used for large-eddy simulations of non-premixed turbulent flames with the Conditional Moment Closure combustion model. The linear relaxation model gives a good estimate of the Favre-filtered scalar dissipation rate throughout the ignition with a value of the related constant close to the one deduced from theoretical arguments. Such value of the constant is one order of magnitude higher than typical values used in Reynolds-averaged approaches. The amplitude mapping closure model provides a satisfactory estimate of the conditionally filtered scalar dissipation rate even in flows characterised by shear driven turbulence and strong density variation.