Search results for "liquid"

How Do Droplets Depend on the System Size? Droplet Condensation and Nucleation in Small Simulation Cells

2003

Using large scale grandcanonical Monte Carlo simulations in junction with a multicanonical reweighting scheme we investigate the liquid-vapor transition of a Lennard—Jones fluid. Particular attention is focused on the free energy of droplets and the transition between different system configurations as the system tunnels between the vapor and the liquid state as a function of system size. The results highlight the finite size dependence of droplet properties in the canonical ensemble and free energy barriers along the path from the vapor to the liquid in the grandcanonical ensemble.

Kernspinlabel-Untersuchungen zur Struktur und Dynamik von flüssigkristallinen Hauptkettenpolymeren

1984

Thermotropic nematic polyesters, specifically deuterated at different positions of the polymer chain, were macroscopically aligned by strong magnetic fields and solid state extrusion. Analysis of the observed 2H NMR spectra was achieved, employing a dynamic NMR model, based on the stochastic Liouville equation. The model considers various double and multiple pulse sequences, recently employed in FT-NMR spectroscopy.

1987

The dielectric relaxation properties of a combined main-chain/side-chain liquid-crystalline polymer were investigated. It was found that the rotation of the side chain about the main chain (δ-process) is not as strongly restricted as in side-chain liquid-crystalline polymers. This is attributed to the facts that the side chain is attached to the flexible spacer within the chain backbone and that the concentration of the side chains is comparatively small. Two low-temperature relaxation processes were observed to occur in the glassy smectic and the crystalline state. They are attributed to intramolecular motions with in the mesogenic groups.

Relation of Interdiffusion and Self-Diffusion in Polymer Mixtures

1986

From different assumptions one obtains linear relationships either between the interdiffusion coefficient and the self-diffusion coefficients or between the inverse interdiffusion coefficient and the inverse self-diffusion coefficients. The nature of these assumptions and possible experiments for discriminating between them are discussed.

Colloidal layers in magnetic fields and under shear flow

2005

The behaviour of colloidal mono- and bilayers in external magnetic fields and under shear is discussed and recent progress is summarized. Superparamagnetic colloidal particles form monolayers when they are confined to a air–water interface in a hanging water droplet. An external magnetic field allows us to tune the strength of the mutual dipole–dipole interaction between the colloids and the anisotropy of the interaction can be controlled by the tilt angle of the magnetic field relative to the surface normal of the air–water interface. For sufficiently large magnetic field strength crystalline monolayers are found. The role of fluctuations in these two-dimensional crystals is discussed. Fur…

Self-assembly in surfactant-based liquid mixtures: Octanoic acid/Bis(2-ethylhexyl)amine systems

2012

Abstract The physico-chemical properties of Bis(2-ethylhexyl)amine (BEEA) plus octanoic acid (OA) mixtures have been investigated by IR, SAXS, WAXS, viscosimetry, and AC complex impedance spectroscopy in the whole composition range. Mainly driven by proton transfer from the acidic OA to the basic BEEA, the formation of stoichiometrically well-defined adducts takes place in the mixtures. This causes the slowing down of molecular dynamics and the increase in charge carrier number density. Interestingly, while the pure components possess no significant conductivity (about 10−12 S cm−1 at 25 °C), their mixtures show a composition-dependent enhanced conductivity (up to about 10−5 S cm−1), i.e., …

A system of conservation laws with discontinuous flux modelling flotation with sedimentation

2019

Abstract The continuous unit operation of flotation is extensively used in mineral processing, wastewater treatment and other applications for selectively separating hydrophobic particles (or droplets) from hydrophilic ones, where both are suspended in a viscous fluid. Within a flotation column, the hydrophobic particles are attached to gas bubbles that are injected and float as aggregates forming a foam or froth at the top that is skimmed. The hydrophilic particles sediment and are discharged at the bottom. The hydrodynamics of a flotation column is described in simplified form by studying three phases, namely the fluid, the aggregates and solid particles, in one space dimension. The relat…

Isobaric Vapor−Liquid Equilibrium of Binary Mixtures of 1-Butanol + Chlorobenzene and 2-Butanol + Chlorobenzene at 20 and 100 kPa

1997

Isobaric vapor−liquid equilibria were obtained for 1-butanol + chlorobenzene and for 2-butanol + chlorobenzene systems at 20 and 100 kPa using a dynamic still. The experimental error in temperature was ±0.1 K, in pressure ±0.01 kPa and ±0.1 kPa for the experiments carried out at 20 and 100 kPa, respectively, and in liquid and vapor composition ±0.001. The two systems satisfy the point-to-point thermodynamic consistency test. Both systems show a positive deviation from ideality. The data were correlated with the Wilson equation.

Control of pesticide residues by liquid chromatography-mass spectrometry to ensure food safety.

2006

Liquid chromatography-mass spectrometry (LC-MS) has become an invaluable technique for the control of pesticide residues to ensure food safety. After an introduction about the regulations that highlights its importance to meet the official requirements on analytical performance, the different mass spectrometers used in this field of research, as well as the LC-MS interfaces and the difficulties associated with quantitative LC-MS determination, are discussed. The ability to use practical data for quantifying pesticides together with the option of obtaining structural information to identify target and non-target parent compounds and metabolites are discussed. Special attention is paid to the…

Déclaration et vérification des créances. Le déclarant a le droit de confirmer ou réduire l'évaluation de sa créance jusqu'à ce que le juge statue

2003

International audience; (Com. 27 mai 2003, pourvoi n° 00-17.716, arrêt n° 867 F-P, Sté Spie Citra c/ Sté EGB Abelli, D. 2003, AJ p. 1631, obs. A. Lienhard)