Search results for "dynamics"
showing 10 items of 9782 documents
Dimensional analysis and upscaling of two-phase flow in porous media with piecewise constant heterogeneities
2004
Dimensional analysis of the traditional equations of motion for two-phase flow in porous media allows to quantify the influence of heterogeneities. The heterogeneities are represented by position dependent capillary entry pressures and position dependent permeabilities. Dimensionless groups quantifying the influence of random heterogeneities are identified. For the case of heterogeneities with piecewise constant constitutive parameters (e.g., permeabilities, capillary pressures) we find that the upscaling ratio defined as the ratio of system size and the scale at which the constitutive parameters are known has to be smaller than the fluctuation strength of the heterogeneities defined, e.g.,…
Phase diagram of polymer blends in confined geometry
2001
Within self-consistent field theory we study the phase behavior of a symmetrical binary AB polymer blend confined into a thin film. The film surfaces interact with the monomers via short range potentials. One surface attracts the A component and the corresponding smei-infinite system exhibits a first order wetting transition. The surface interaction of the opposite surface is varied as to study the crossover from capillary condensation for symmetric surfaces fields to the interface localization/delocalization transition for antisymmetric surface fields. In the former case the phase diagram has a single critical point close to the bulk critical point. In the latter case the phase diagram exh…
Effects of finite thickness on interfacial widths in confined thin films of coexisting phases
1999
The capillary broadening of a 2-phase interface is investigated both experimentally and theoretically. When a binary mixture in a thin film with thickness D segregates into two coexisting phases the interface between the two phases may form parallel to the substrate due to preferential surface attraction of one of the components. We show that the interfacial profile (of intrinsic width w0) is broadened due to capillary waves, which lead to fluctuations, of correlation length of the local interface positions in the directions parallel to the confining walls. We postulate that acts as an upper cutoff for the spectrum of capillary waves on the interface, so that the effective mean square inter…
Computer simulation studies of finite-size broadening of solid–liquid interfaces: from hard spheres to nickel
2009
Using Molecular Dynamics (MD) and Monte Carlo (MC) simulations interfacial properties of crystal-fluid interfaces are investigated for the hard sphere system and the one-component metallic system Ni (the latter modeled by a potential of the embedded atom type). Different local order parameters are considered to obtain order parameter profiles for systems where the crystal phase is in coexistence with the fluid phase, separated by interfaces with (100) orientation of the crystal. From these profiles, the mean-squared interfacial width w^2 is extracted as a function of system size. We rationalize the prediction of capillary wave theory that w^2 diverges logarithmically with the lateral size o…
PHASE EQUILIBRIA IN THIN POLYMER FILMS
2001
Within self-consistent field theory and Monte Carlo simulations the phase behavior of a symmetrical binary AB polymer blend confined into a thin film is studied. The film surfaces interact with the monomers via short ranged potentials. One surface attracts the A component and the corresponding semi-infinite system exhibits a first order wetting transition. The surface interaction of the opposite surface is varied as to study the crossover from capillary condensation for symmetric surface fields to interface localization/delocalization transition for antisymmetric surface fields. In the former case the phase diagram has a single critical point close to the bulk critical point. In the latter…
Observation of topological gravity-capillary waves in a water wave crystal
2019
The discovery of topological phases of matter, initially driven by theoretical advances in quantum condensed matter physics, has been recently extended to classical wave systems, reaching out to a wealth of novel potential applications in signal manipulation and energy concentration. Despite the fact that many realistic wave media (metals at optical frequencies, polymers at ultrasonic frequencies) are inherently dispersive, topological wave transport in photonic and phononic crystals has so far been limited to ideal situations and proof-of-concept experiments involving dispersionless media. Here, we report the first experimental demonstration of topological edge states in a classical water …
Thermodynamic analysis of binding between drugs and glycosaminoglycans by isothermal titration calorimetry and fluorescence spectroscopy
2007
The thermodynamics of the interaction of positively charged drug molecules with negatively charged glycosaminoglycans (GAGs) is investigated by isothermal titration calorimetry (ITC) and fluorescence spectroscopy. The drugs considered are propranolol hydrochloride, tacrine, and aminacrine, and the polymers used as model GAGs are dextran sulfate, chondroitin sulfate, and hyaluronic acid. The ITC results show that the interaction between drugs and GAGs is via direct binding and that GAGs bind to drugs at one set of sites. Large negative values of heat capacity change (DeltaC(p)) are observed upon binding of GAGs to drugs. Such negative DeltaC(p) is not expected for purely electrostatic intera…
Mapping the network of pathways of CO diffusion in myoglobin.
2010
The pathways of diffusion of a CO molecule inside a myoglobin protein and toward the solvent are investigated. Specifically, the three-dimensional potential of mean force (PMF or free energy) of the CO molecule position inside the protein is calculated by using the single-sweep method in concert with fully resolved atomistic simulations in explicit solvent. The results are interpreted under the assumption that the diffusion of the ligand can be modeled as a navigation on the PMF in which the ligand hops between the PMF local minima following the minimum free energy paths (MFEPs) with rates set by the free energy barriers that need to be crossed. Here, all the local minima of the PMF, the MF…
Mass Transport Analysis of Bicarbonate Buffer: Effect of the CO2–H2CO3 Hydration–Dehydration Kinetics in the Fluid Boundary Layer and the Apparent Ef…
2019
The main buffering system influencing ionizable drug dissolution in the human intestinal fluid is bicarbonate-based; however, it is rarely used in routine pharmaceutical practice due to the volatility of dissolved CO2. The typical pharmaceutical buffers used fail to capture the unique aspects of the hydration-dehydration kinetics of the bicarbonate-CO2 system. In particular, CO2 is involved in a reversible interconversion with carbonic acid (H2CO3), which is the actual conjugate acid of the system, as follows CO2 + H2O ⇌ H2CO3. In contrast to ionization reactions, this interconversion does not equilibrate very rapidly compared to the diffusional processes through a typical fluid diffusion b…
Intracoronary application of C1 esterase inhibitor improves cardiac function and reduces myocardial necrosis in an experimental model of ischemia and…
1997
Background Myocardial injury from ischemia can be aggravated by reperfusion of the jeopardized area. The precise underlying mechanisms have not been clearly defined, but proinflammatory events, including complement activation, leukocyte adhesion, and infiltration and release of diverse mediators, probably play important roles. The present study addresses the possibility of reducing reperfusion damage by the application of C1 esterase inhibitor (C1-INH). Methods and Results Cardioprotection by C1-INH 20 IU/kg IC was examined in a pig model with 60 minutes of coronary occlusion, followed by 120 minutes of reperfusion. C1-INH was administered during the first 5 minutes of coronary reperfusion…