Search results for "Kinetics"
showing 10 items of 2224 documents
The application of Jäntti's method for the fast calculation of equilibrium in case of multilayer adsorption
2002
On the basis of a molecular model for sorption kinetics Jäntti introduced a method to calculate equilibria shortly after a change of the pressure of the sorptive gas. In the present paper we apply that method for the description of multilayer adsorption.
Temperature influence on NaLaF 4 :Er 3+ green luminescence
2016
Abstract Er 3+ doped NaLaF 4 is a promising material for up-conversion luminescence applications due to low phonon energy and multisite nature of the crystalline lattice. In this work, luminescence processes in NaLaF 4 :Er 3+ materials have been studied at different temperatures. Spectra and decay kinetics of the green luminescence were measured under excitation to 4 F 7/2 state. Analysis of the green luminescence excitation spectra, the luminescence spectra and the luminescence decay kinetics at different temperatures reveals that the observed single green luminescence spectra at room temperature are related to overlapping of the green luminescence excitation bands from erbium ions located…
Spinodal Decomposition Kinetics of Colloid-Polymer Mixtures Including Hydrodynamic Interactions
2012
The phase separation dynamics of a model colloid-polymer mixture is studied by taking explicitly the hydrodynamic interactions caused by the solvent into account. Based on the studies on equilibrium phase behavior we perform a volume quench from the homogeneous region of the phase diagram deep into the region where colloid-rich and polymer-rich phases coexist. We demonstrate that the Multiparticle Collision Dynamics (MPCD) algorithm is well suited to study spinodal decomposition and present first results on the domain growth behavior of colloid-polymer mixtures in quasi two-dimensional confinement. On the one hand side we find that the boundary condition of the solvent with respect to the r…
Wetting and phase separation at surfaces
2005
We study the problem ofsurfacedirected spinodal decomposition, viz., the dynamical interplay of wetting and phase separation at surfaces. In particular, we focus on the kinetics of wetting-layer growth in a semi-infinite geometry for arbitrary surface potentials and mixture compositions. We also present representative results for phase separation in confined geometries, e.g., cylindrical pores, thin films, etc.
The Study of Carbamoyl Phosphate Synthetase 1 Deficiency Sheds Light on the Mechanism for Switching On/Off the Urea Cycle
2015
12 páginas, 4 figuras, 2 tablas.
Protofibril formation of amyloid beta-protein at low pH via a non-cooperative elongation mechanism.
2005
Deposition of the amyloid beta-protein (Abeta) in senile or diffuse plaques is a distinctive feature of Alzheimer's disease. The role of Abeta aggregates in the etiology of the disease is still controversial. The formation of linear aggregates, known as amyloid fibrils, has been proposed as the onset and the cause of pathological deposition. Yet, recent findings suggest that a more crucial role is played by prefibrillar oligomeric assemblies of Abeta that are highly toxic in the extracellular environment. In the present work, the mechanism of protofibril formation is studied at pH 3.1, starting from a solution of oligomeric precursors. By combining static light scattering and photon correla…
Evaluating the protecting effects of two consolidants applied on Pietra di Lecce limestone: A neutronographic study
2020
Abstract In this work a combined laboratory-based and neutronographic investigation was carried out on a type of limestone, known as Pietra di Lecce stone, widely used in Italian Baroque as construction material. The limestone was treated with two different commercially-available coatings, namely nanosilica and nanolime, and artificially weathered by salt crystallization and temperature/relative humidity jumps. The aim was to provide an experimental evidence of the protective and consolidating effectiveness of the two treatments by looking at the water absorption process occurring inside the pore network of the analyzed stones. The analysis of the wetting front position revealed significant…
Comparative Analysis of the Vascular Actions of Diterpenes Isolated from Euphorbia canariensis
1998
Abstract We have analysed the effects of 2,3-diepiingol 7,12-diacetate-8-isobutyrate (compound 1), ingenol-3-angelate-17-benzoate (compound 2), ingenol-3-angelate-17-benzoate-20-acetate (compound 3) and 3,5,7,8,9,15-hexahydroxyjatropha-6(17),11-dien-14-one-5,8-bis(2-methylbutyrate)-7-(2-methylpropionate) (compound 4), four diterpenes isolated from E. canariensis, on the isometric tension developed by isolated rabbit basilar and carotid arteries. Concentration-response curves to these compounds were obtained cumulatively in both arteries at resting tension and active tone (KCl, 50 mM). At resting tension a concentration-dependent contraction was induced by the four compounds. In the basilar …
Ethyl Hexanoate Transfer Modeling in Carrageenan Matrices for Determination of Diffusion and Partition Properties.
2007
; Aroma compound properties in food matrices, such as volatility and diffusivity, have to be determined to understand the effect of composition and structure on aroma release and perception. This work illustrates the use of mass transfer modeling to identify diffusion and partition properties of ethyl hexanoate in water and in carrageenan matrices with various degrees of structure. The comparison of results obtained with a diffusive model to those obtained with a convective model highlights the importance of considering the appropriate transfer mechanism. Modeling of the preliminary experimental steps ensures correct estimation of the conditions for the main aroma release step. The obtaine…
Two-Dimensional Modeling of a Flat-Plate Photocatalytic Reactor for Oxidation of Indoor Air Pollutants
2007
In this paper we present a two-dimensional (2-D) analysis of a narrow-slit, flat-plate, single-pass, flow-through photocatalytic reactor for air purification. The continuity equation for convection and diffusion in two dimensions, under un-steady-state conditions, was coupled with radiation field modeling and photocatalytic reaction kinetics to model the transient and steady-state behavior of the reactor. The model was applied to the photocatalytic oxidation of trichloroethylene (TCE) in humidified air streams under different experimental conditions. The kinetic parameters determined by a three-dimensional (3-D) computational fluid dynamics model of the reactor were used in the 2-D model si…