Search results for "fluid"
showing 10 items of 5513 documents
Dragging a Polymer Chain into a Nanotube and Subsequent Release
2008
We present a scaling theory and Monte Carlo (MC) simulation results for a flexible polymer chain slowly dragged by one end into a nanotube. We also describe the situation when the completely confined chain is released and gradually leaves the tube. MC simulations were performed for a self-avoiding lattice model with a biased chain growth algorithm, the pruned-enriched Rosenbluth method. The nanotube is a long channel opened at one end and its diameter $D$ is much smaller than the size of the polymer coil in solution. We analyze the following characteristics as functions of the chain end position $x$ inside the tube: the free energy of confinement, the average end-to-end distance, the averag…
High Pressure Solubility Data of the System Limonene + Linalool + CO2
2001
The feasibility of deterpenating orange peel oil with supercritical CO2 depends on relevant vapor−liquid equilibrium data because the selectivity of this solvent for limonene and linalool (the two key components of the oil) is of crucial importance. In this work the solubility data for the CO2 + limonene + linalool ternary system were measured at (318.2 and 328.2) K. The range of pressures covered was from (70 to 110) bar. Two different mixtures of limonene + linalool were used: a 40 mass % limonene + 60 mass % linalool mixture and a 60 mass % limonene + 40 mass % linalool mixture. To correlate the obtained results, two equations of state were successfully used (Peng−Robinson (PR) and Soav…
Bimodal Effect of Amphiphilic Biocide Concentrations on Fluidity of Lipid Membranes
1996
Abstract Using the spin label method (ESR) it has been shown that biologically active, amphiphilic compounds (quaternary ammonium salts -AS) containing polar heads with single and double positive charge caused, at low concentrations, decrease fluidity of liposome membranes formed with egg yolk lecithin (EYL). At higher concentrations an increase in fluidity was observed. With compounds having a single positive charge minimum fluidity of membrane structure occurs in the range of 1 to 3%, with compounds containing double positive charge -in the range of 4 -6 % . That effect does not depend on polar head size and length of alkyl chains of the AS used. Analysis of the electrostatic interaction …
Fluidity of liposome membranes doped with organic tin compounds: ESR study.
2008
The kinetics of change in the fluidity of liposome membranes, obtained in the process of sonication of Egg Yolk Lecithin (EYL), with the admixture of organic tin compounds, was investigated. Five compounds were selected for the research: three differed in the length of hydrocarbon chains, (CH(3))(4)Sn, (C(2)H(5))(4)Sn, and (C(3)H(7))(3)SnCl, whereas two differed in the number of aromatic rings, (C(6)H(5))(2)SnCl(2) and (C(6)H(5))(3)SnCl. The concentration of the compounds in proportion to EYL was 2 mol-%. Electron Spin (paramagnetic) Resonance (ESR) was applied using two spin probes TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl) and 16-DOXYL-stearic acid methyl ester (2-ethyl-2-(15-methoxy-15…
Adaptive Wetting-Adaptation in Wetting
2018
Many surfaces reversibly change their structure and interfacial energy upon being in contact with a liquid. Such surfaces adapt to a specific liquid. We propose the first order kinetic model to describe dynamic contact angles of such adaptive surfaces. The model is general and does not refer to a particular adaptation process. The aim of the proposed model is to provide a quantitative description of adaptive wetting and to link changes in contact angles to microscopic adaptation processes. By introducing exponentially relaxing interfacial energies and applying Young's equation locally, we predict a change of advancing and receding contact angles depending on the velocity of the contact line…
Magnetic Soret effect in a hydrocarbon based colloid containing surfacted Mn–Zn ferrite particles
1999
Abstract The Soret effect has been investigated in a hydrocarbon based magnetic fluid containing surfacted Mn 0.5 Zn 0.5 Fe 2 O 4 nanoparticles with a magnetic volume concentration of 2.3%. The magnetic fluid fills up a vertical diffusion column which consists of a flat vertical channel between two walls and two reservoirs at the ends of the channel. One wall of the channel is being heated while the another one is cooled, maintaining a temperature gradient over the channel's width that leads to separation of particles due to the Soret effect as well as the convective flow in the channel. The combination of the two mentioned effects brings up a measurable change of the concentration of magne…
Effect of carboxymethyl cellulose concentration on rheological behavior of milk and aqueous systems. A creep and recovery study
2009
Carboxymethyl cellulose (CMC) is an anionic polysaccharide used mainly as stabilizer and thickener agent. The purpose of this study was to investigate the effect of CMC concentration on viscoelasticity of dairy and aqueous model systems through the analysis of creep and recovery tests. The viscoelastic properties of different concentrations of CMC (0.75, 1.00, 1.25, and 1.50% w/w) in two milk systems (skimmed milk and whole milk) were compared with those of the same concentration of biopolymer in aqueous solution. Creep curves were fitted to a six parameter mechanical model (Burger + Kelvin-Voigt), whereas an empirical equation was used for recovery. The creep and recovery properties of sam…
Fast and continuous synthesis of nanostructured iron spinel in supercritical water: influence of cations and citrates
2014
International audience; Spinel iron oxide nanoparticles were obtained under supercritical water conditions in a continuous and fast (less than 10s) way by modifying the initial stoichiometric Fe II /Fe III molar ratio from (1/2) to (3/0), without base solution, and using citrates directly with iron precursors. This result opens the way of an economical and environmentally benign approach to synthesize superparamagnetic iron oxide nanoparticles (SPIONs) in important yields.
Nematic elastomers: From a microscopic model to macroscopic elasticity theory
2008
A Landau theory is constructed for the gelation transition in cross-linked polymer systems possessing spontaneous nematic ordering, based on symmetry principles and the concept of an order parameter for the amorphous solid state. This theory is substantiated with help of a simple microscopic model of cross-linked dimers. Minimization of the Landau free energy in the presence of nematic order yields the neoclassical theory of the elasticity of nematic elastomers and, in the isotropic limit, the classical theory of isotropic elasticity. These phenomenological theories of elasticity are thereby derived from a microscopic model, and it is furthermore demonstrated that they are universal mean-fi…
Expanded micro-particles by supercritical antisolvent precipitation: Interpretation of results
2008
Abstract Supercritical antisolvent (SAS) micronization has been used to obtain nanoparticles and micro-particles of several kinds of materials. Sometimes hollow expanded micro-particles have also been obtained. This work is focused on the analysis of this last morphology. We organized literature data and our previous experiments and we added new experiments on previously tested compounds and on compounds never tested before. As a result, expanded micro-particles using several compounds belonging to different categories and precipitated from different solvents in laboratory and pilot scale plants were obtained with diameters between about 10 and 180 μm. They also showed different sub-structu…