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Full-Text Articles in Engineering

Anhydrous Praseodymium Salts In The Ionic Liquid [Bmpyr][Tf2n]:  Structural And Optical Properties Of [Bmpyr]4[Pri6][Tf2n] And [Bmyr]2[Pr(Tf2n)5], Arash Babai, Anja V. Mudring Jan 2005

Anhydrous Praseodymium Salts In The Ionic Liquid [Bmpyr][Tf2n]:  Structural And Optical Properties Of [Bmpyr]4[Pri6][Tf2n] And [Bmyr]2[Pr(Tf2n)5], Arash Babai, Anja V. Mudring

Anja V. Mudring

Purposely designed ionic liquids can be excellent solvents for spectroscopic studies of rare earth compounds. Absorption and emission spectra of anhydrous PrI3 and Pr(Tf2N)3 in the ionic liquid 1,1-n-butyl-methylpyrrolidinium bis(trifluoromethanesulfonyl)amide, [bmpyr][Tf2N], at room temperature are presented together with the emission spectra of solid [bmpyr]2[Pr(Tf2N)5] and [bmpyr]4[PrI6][Tf2N]. After excitation into the 3P1 level, remarkable luminescence not only from the 1D2 level but also from the 3P0 and even from the 3P1 level is observed. Amazingly in the case of the solid compounds and even more astonishing for a solution of Pr(Tf2N)3 in [bmpyr][Tf2N] the strongest luminescence transitions start from the 3P0 …


Lone Pair Effect In Thallium(I) Macrocyclic Compounds, Anja V. Mudring, Franziska Rieger Jan 2005

Lone Pair Effect In Thallium(I) Macrocyclic Compounds, Anja V. Mudring, Franziska Rieger

Anja V. Mudring

The role of the inert (lone) pair of electrons in thallium(I) salts is studied by comparison of the compounds [Tl@18-crown-6]+X- (X = TlI4, ClO4) and [K@18-crown-6]+ClO4-. In contrast to common introductory chemistry textbook opinions, the paradigm that s−p hybridization is a prerequisite for an inert electron pair to become stereochemically active in compounds of the heavier main group elements has to be revised. Instead, an inert pair of electrons is expected to become stereochemically involved whenever it is forced to participate in antibonding orbital interactions with its surroundings, and there is the possibility for a structural distortion that minimizes these …


Solid-Liquid Phase Equilibrium For Binary Lennard-Jones Mixtures, Monica R. Hitchcock, Carol K. Hall Jun 1999

Solid-Liquid Phase Equilibrium For Binary Lennard-Jones Mixtures, Monica R. Hitchcock, Carol K. Hall

Monica H. Lamm

Solid-liquid phase diagrams are calculated for binary mixtures of Lennard-Jones spheres using Monte Carlo simulation and the Gibbs-Duhem integration technique of Kofke. We calculate solid-liquid phase diagrams for the model Lennard-Jones mixtures: argon-methane, krypton-methane, and argon-krypton, and compare our simulation results with experimental data and with Cottin and Monson's recent cell theory predictions. The Lennard-Jones model simulation results and the cell theory predictions show qualitative agreement with the experimental phase diagrams. One of the mixtures, argon-krypton, has a different phase diagram than its hard-sphere counterpart, suggesting that attractive interactions are an important consideration in determining solid-liquid phase behavior. We then …


Hydrodynamics Of Dispersed Liquid Droplets In Agitated Synthetic Fibrous Slurries, Theodore J. Heindel, Feler Bose, S. Mostafa Ghiaasiaan Nov 1997

Hydrodynamics Of Dispersed Liquid Droplets In Agitated Synthetic Fibrous Slurries, Theodore J. Heindel, Feler Bose, S. Mostafa Ghiaasiaan

Theodore J. Heindel

The hydrodynamic and liquid particle dispersion processes in agitated vessels containing dilute liquid−liquid dispersions, and dilute liquid dispersions in synthetic fibrous slurries, were experimentally studied. A transparent cylindrical vessel 25 cm in height and 15.5 cm in diameter equipped with a six-blade impeller, with geometric proportions representing the standard vessel configuration, was used. The steady-state size distributions of molten wax particles, which constituted 1% by weight of the mixture everywhere, in pure water, and in aqueous slurries with 0.1%, 0.5%, 0.8%, and 1.0% consistencies of nylon fibers, were measured using sampling and microscopic image analyses. The average nylon fiber length …