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1
Gomez, Gil Leticia. "The interaction between cholesterol and surfactant protein-c in lung surfactant". Doctoral thesis, Universite Libre de Bruxelles, 2009. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210205.
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The presence of cholesterol is critical in defining a dynamic lateral structure in pulmonary surfactant membranes, including the segregation of fluid-ordered and fluid-disordered phases.
However, an excess of cholesterol has been associated with impaired surface activity both in
surfactant models and in surfactant from injured lungs. It has also been reported that surfactant
protein SP-C interacts with cholesterol in lipid/protein interfacial films. In the present study, we
have analyzed the effect of SP-C on the thermodynamic properties of phospholipid membranes
containing cholesterol and on the ability of lipid/protein complexes containing surfactant
proteins and cholesterol to form and re-spread interfacial films capable of producing very low
surface tensions upon repetitive compression-expansion cycling. We have also analyzed the effect of cholesterol on the
structure, orientation and dynamic properties of SP-C embedded in physiologically relevant
model membranes.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished
2
Farnoud, Amir Mohammad. "Interaction of polymeric particles with surfactant interfaces". Diss., University of Iowa, 2013. https://ir.uiowa.edu/etd/4627.
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Films of phospholipids and biologically relevant surfactants at the air-water interface provide a well-defined medium to study molecular alignment, phase behavior and interactions of biomembranes and lung surfactant with exogenous materials. Interactions between lung surfactant interfaces and solid particles are of particular interest due to the increased use of nanomaterials in industrial applications and the promise of polymeric particles in pulmonary drug delivery. Understanding such interactions is necessary to avoid potential adverse effects on surfactant function after exposure to particles.
In this thesis, the mechanisms of surfactant inhibition after exposure to submicron particles via different routes were investigated. The effects of carboxyl-modified polystyrene particles (200 nm) on films of dipalmitoyl phosphatidylcholine (DPPC) and Infasurf (calf lung surfactant extract) were studied. Surfactants were exposed to different concentrations of particles in a Langmuir trough with symmetric surface compression and expansion. Surface tension, potential, microstructure and topology were examined to monitor particle effects on surfactant function. Several methods of surfactant exposure to particles were studied: particle injection into the subphase after spreading surfactant monolayers (subphase injection), mixing the particles with the subphase and spreading the surfactant on top (monolayer addition) and particle aerosolization onto surfactant films.
Studies with DPPC monolayers revealed that particle-surfactant interactions are dependent on the particle introduction method. In the subphase injection method, particles did not penetrate the monolayer and no inhibitory effects on surfactant function were observed. However, in the monolayer addition method, particles caused a premature monolayer collapse and hindered surfactant respreading likely by penetrating into the DPPC monolayer. Finally, particle aerosolization on surfactant was performed to mimic the physiologically relevant route of surfactant exposure to particles. Particle aerosolization on DPPC monolayers significantly inhibited surfactant function in the lung-relevant surface tension range. When aerosolized on Infasurf, particles caused inhibitory effects as a function of time suggesting adsorption of surfactant components on particle surfaces as the main mechanism of interaction. This research will enhance understanding of the mechanisms of particle-induced surfactant dysfunction, thereby providing information for the safe design of polymeric particles for drug delivery and for developing guidelines for particles used in occupational settings.
3
Windsor, Rosemary. "Polymer surfactant interaction studied by sum frequency spectroscopy". Thesis, University of Cambridge, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620464.
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4
Carnell, Sarah. "Surfactant interaction and persistence at the contact lens surface". Thesis, Aston University, 2015. http://publications.aston.ac.uk/37488/.
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The interaction of poloxamer and poloxamine (Pluronic® and Tetronic®) surfactants with hydrogel and silicone hydrogel contact lens surfaces is of interest for this thesis. The persistence of surfactant molecules at the lens surface can indicate how long the surface has been modified. It is therefore important to observe and characterise the surface and surfactant behaviour separately. Characterisation of the contact lenses was carried out through dehydrated sessile drop measurements and surface energy calculations. Silicone-containing materials tended to be most hydrophobic regardless of water content. Static and dynamic surface tension measurements were used to assess the surfactants and the critical micelle concentration was also observed. Pluronics® and Tetronics® do not behave as simple low molecular weight surfactants; their structure and size mean they are less mobile in solution and may be able to form mono molecular micelles. Surfactants with different molecular structure, molecular weight and hydrophobicity were used to observe how these properties affect surface tension behaviour and influence surfactant persistence. The aim of the work was observe the persistence of surfactants at the lens surface, any difference between the surfactant persistence, and the possibility to predict surfactant persistence on a lens. The ex vivo work presented here shows little distinction between surface tension measurements over time or between treated and untreated materials. It is not possible to measure in vivo surfactant persistence with surface tension techniques and therefore necessary to create in vitro models to assess surfactant behaviour. A simplified in vitro eye model was created to assess preliminary observations. These results and observations were used to progressively alter the model and create a more ‘eye-like’ system. Large hydrophobic Tetronics® were most persistent at the lens surface; hydrophobic drive was considered the most influential factor. In addition to this, the contact lens material and condition prior to surfactant treatment also had an effect on persistence. Materials containing PVP showed increased surfactant persistence, which was increased further when the lenses were dehydrated prior to surfactant treatment. Lens dehydration had no effect on persistence if PVP was not present in the lens material.
5
McKenzie, Zofi. "Nanotoxicology : nanoparticle interaction with surfactant proteins A and D". Thesis, University of Southampton, 2013. https://eprints.soton.ac.uk/390356/.
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Numerous epidemiological and toxicological studies have associated enhanced exposure to ambient air pollution with reduced resolution and increased incidence of respiratory infections. Surfactant Proteins A (SP-A) and SP-D are innate immune molecules within the lung and are important mediators in the resolution and clearance of microbial infections. They have also been implicated in the opsonisation and clearance of inorganic particulates in vitro. This study aimed to investigate the interaction of SP-A and SP-D with model 100nm unmodified (U-PS) and amine modified polystyrene (A-PS) nanoparticles. Firstly, it was hypothesised that the particle interaction with these proteins would alter particle clearance by macrophages and secondly that the sequestration of SP-A and SP-D by particles would result in a reduction in the anti-microbial function of these proteins. SP-A and SP-D were purified from the bronchoalveolar lavage fluid of subjects with alveolar proteinosis. Using absorption, turbidity, size and zeta potential measurements SP-A and SP-D were shown to interact with A-PS and U-PS particles and the extent of these interactions were dependent on the zeta potential of the particles. SP-A and SP-D altered the colloidal stability of the particles and this was related to the effect of each protein on the differential particle uptake by macrophages. In vitro influenza A virus (IAV) infection models were optimised using flow cytometry to detect surfactant protein mediated neutralisation of this virus at sub-maximal levels in cell lines representing cells found within the alveolus. These models were used to study the effect of U-PS and A-PS particles on surfactant protein mediated neutralisation of IAV. The results showed that nanoparticles can modulate the vitro function of SP-A and SP-D in a biphasic fashion in alveolar epithelial cells. However, this effect was dependent on a number of factors, including the particle, the protein and cell type under investigation. The identification of unlabelled lipids and nanoparticles in vitro by coherent anti-stokes raman scattering (CARS) was also be discussed.
6
Hohenschutz, Max. "Nano-ions in interaction with non-ionic surfactant self-assemblies". Thesis, Montpellier, 2020. http://www.theses.fr/2020MONTS064.
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Les ions de taille nanométrique (nano-ions), tels que les clusters ioniques de bore, les polyoxométalates (POM) et les grands ions organiques, ont suscité un intérêt remarquable ces dernières années en raison de leur capacité à s’adsorber ou se lier à des systèmes chimiques électriquement neutres, tels que les molécules hôtes macrocycliques, les nanoparticules, les tensioactifs et les polymères, etc. Il a été démontré que ces processus d'adsorption ou de liaison sont induits par un phénomène médié par solvant, l'effet chaotropique, qui pousse le nano-ion de la masse d'eau vers une interface. Ainsi, l'eau d'hydratation de l'ion et de l'interface est libérée dans la masse d'eau, ce qui entraîne une restitution de la structure intrinsèque de l'eau. Cet effet est particulièrement fort pour les nano-ions. Ils sont par conséquent appelés ions superchaotropiques ou hydrophobes dans le prolongement des ions classiques (faiblement) chaotropiques tels que le SCN-. Tous les superchaotropes couramment étudiés, bien que chimiquement divers, partagent des caractéristiques physiques telles qu'une faible densité de charge et une grande polarisabilité. Les effets des nano-ions sur les auto-assemblages de tensioactifs non ioniques éthoxylés, les phases micellaires et bicouches, sont ici élucidés pour tirer des conclusions sur leur nature chaotropique et/ou hydrophobe. En combinant la diffusion aux petits angles des neutrons et des rayons X (SANS et SAXS), et les diagrammes de phase, les systèmes tensioactifs non ioniques/nano-ion sont examinés et comparés, du nanomètre à l'échelle macroscopique. Ainsi, il est montré que tous les nano-ions étudiés induisent un chargement électrique des assemblages de tensioactifs ainsi qu'une déshydratation des têtes de tensioactif non-ionique. En outre, les ions chaotropiques ou hydrophobes diffèrent dans leurs effets sur la forme micellaire. Les ions chaotropiques entraînent les micelles allongées de tensioactif non-ionique vers les micelles sphériques (augmentation de la courbure), tandis que les ions hydrophobes provoquent une transition vers les phases bicouches (diminution de la courbure). Il est conclu que les nano-ions superchaotropiques agissent comme des tensioactifs ioniques car leur ajout à des systèmes de tensioactifs non ioniques provoque un effet de charge. Cependant, les nano-ions et les tensioactifs ioniques sont fondamentalement différents par leur association avec l'ensemble des tensioactifs non ioniques. Le nano-ion s'adsorbe sur les têtes des tensioactifs non ioniques par effet chaotropique, tandis que le tensioactif ionique s'ancre dans les micelles entre les queues des tensioactifs non ioniques par effet hydrophobe. La comparaison des effets de l'ajout de nano-ions ou de tensioactifs ioniques à des tensioactifs non ioniques a été approfondie sur les mousses. Les mousses ont été étudiées en ce qui concerne l'épaisseur du film de mousse, le drainage dans le temps et la stabilité, respectivement en utilisant la SANS, l'analyse d'image et la conductométrie. Le POM superchaotropique testé (SiW12O404-, SiW) ne mousse pas dans l'eau contrairement au SDS classique de tensioactif ionique. Néanmoins, l'ajout de petites quantités de SiW ou de SDS à une solution moussante de tensioactif non ionique a permis d'obtenir des mousses plus humides avec une durée de vie plus longue. Entre-temps, l'épaisseur du film de mousse (déterminée en SANS) est augmentée en raison de la charge électrique des monocouches de tensioactifs non ioniques dans le film de mousse. Il est conclu que le comportement remarquable des nano-ions - ici sur les systèmes tensioactifs non ioniques - peut être étendu aux systèmes colloïdaux, tels que les mousses, les polymères, les protéines ou les nanoparticules. Cette thèse démontre que le comportement superchaotropique des nano-ions est un outil polyvalent qui peut être utilisé dans de nouvelles formulations de matériaux et d'applications de la matière molleNanometer-sized ions (nano-ions), such as ionic boron clusters, polyoxometalates (POMs) and large organic ions, have spawned remarkable interest in recent years due to their ability to adsorb or bind to electrically neutral chemical systems, such as macrocyclic host molecules, colloidal nano-particles, surfactants and polymers etc. The underlying adsorption or binding processes were shown to be driven by a solvent-mediated phenomenon, the chaotropic effect, which drives the nano-ion from the water bulk towards an interface. Thus, hydration water of the ion and the interface is released into the bulk resulting in a bulk water structure recovery. This effect is particularly strong for nano-ions. Therefore, they were termed superchaotropic or hydrophobic ions as an extension to classical (weakly) chaotropic ions such as SCN-. All commonly studied superchaotropes, though chemically diverse, share physical characteristics such as low charge density and high polarizability. Herein, the effects of nano-ions on ethoxylated non-ionic surfactant self-assemblies, micellar and bilayer phases, are elucidated to draw conclusions on their chaotropic and/or hydrophobic nature. By combining small angle scattering of neutrons and x-rays (SANS and SAXS), and phase diagrams, non-ionic surfactant/nano-ion systems are examined and compared, from the nanometer to the macroscopic scale. Thus, all studied nano-ions are found to induce a charging of the surfactant assemblies along with a dehydration of the non-ionic surfactant head groups. Furthermore, chaotropic and hydrophobic ions differ in their effects on the micellar shape. Superchaotropic ions drive the elongated non-ionic surfactant micelles towards spherical micelles (increase in curvature), whereas hydrophobic ions cause a transition towards bilayer phases (decrease in curvature). It is concluded that superchaotropic nano-ions act like ionic surfactants because their addition to non-ionic surfactant systems causes a charging effect. However, nano-ions and ionic surfactants are fundamentally different by their association with the non-ionic surfactant assembly. The nano-ion adsorbs to the non-ionic surfactant heads by the chaotropic effect, while the ionic surfactant anchors into the micelles between the non-ionic surfactant tails by the hydrophobic effect. The comparison of the effects of adding nano-ions or ionic surfactant to non-ionic surfactant was further investigated on foams. The foams were investigated regarding foam film thickness, drainage over time and stability, respectively using SANS, image analysis and conductometry. The tested superchaotropic POM (SiW12O404-, SiW) does not foam in water in contrast to the classical ionic surfactant SDS. Nevertheless, addition of small amounts of SiW or SDS to a non-ionic surfactant foaming solution resulted in wetter foams with longer lifetimes. Meanwhile, the foam film thickness (determined in SANS) is increased due to the electric charging of the non-ionic surfactant monolayers in the foam film. It is concluded that the remarkable behavior of nano-ions – herein on non-ionic surfactant systems – can be extended to colloidal systems, such as foams, polymers, proteins or nanoparticles. This thesis demonstrates that the superchaotropic behavior of nano-ions is a versatile tool to be used in novel formulations of soft matter materials and applications
7
Crichton, Donna. "The interaction of oils with surfactant monolayers at the air-water surface". Thesis, University of Hull, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310247.
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8
Ocampo, Minette C. "Protein-Lipid Interactions with Pulmonary Surfactant Using Atomic Force Microscopy". The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1395050693.
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9
Höhn, Sebastian [Verfasser]. "Interaction of Pluronic polymers with sugar surfactant in microemulsions designed for decontamination / Sebastian Höhn". Bielefeld : Universitätsbibliothek Bielefeld, 2016. http://d-nb.info/1101694106/34.
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10
Nilsson, Peter. "Interaction between Crosslinked Polyelectrolyte Gels and Oppositely Charged Surfactants". Doctoral thesis, Uppsala University, Department of Pharmacy, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-8216.
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The interactions between anionic, crosslinked gels and cationic surfactants have been investigated. When exposed to oppositely charged surfactant, the gel collapses into a dense complex of polyion and micelles. During deswelling, the gel phase separates into a micelle-rich, collapsed surface phase, and a swollen, micelle-free core, both still part of the same network. As more surfactant is absorbed, the surface phase grows at the expense of the core, until the entire gel has collapsed. Polyacrylate (PA) gels with dodecyl- (C12TAB), and cetyltrimethylammonium bromide (C16TAB), as well as hyaluronate gels with cetylpyridinium chloride, have been studied.
Kinetic experiments have been performed on macro- as well as microgels, using micromanipulator assisted light microscopy for the latter. A surfactant diffusion controlled deswelling model has been employed to describe the deswelling. The deswelling kinetics of PA microgels have been shown to be controlled by surfactant diffusion through the stagnant layer surrounding the gel, as the surface phase is relatively thin for the major part of the deswelling. For macroscopic PA gels the surface phase is thicker, and the kinetics with C12TAB were therefore also influenced by diffusion through the surface phase, while for C16TAB they were dominated by it.
Relevant parameters have also been determined using equilibrium experiments. An irregular, balloon-forming deswelling pattern, mainly found for macrogels, as well as unexpectedly long lag times and slow deswelling for microgels, are reported and discussed.
The microstructure of fully collapsed PA/C12TAB complexes has been studied using small-angle X-ray scattering. A cubic Pm3n structure was found at low salt concentration, which melted into a disordered micellar phase as the salt concentration was increased. Further increasing the salt concentration dissolved the micelles, resulting in no ordering.
11
Svanedal, Ida. "Fundamental Characterization and Technical Aspects of a Chelating Surfactant". Doctoral thesis, Mittuniversitetet, Avdelningen för kemiteknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-21405.
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The purpose of this study was to investigate the fundamental characteristics of a chelating surfactant in terms of solution behaviour, chelation of divalent metal ions, and interaction in mixtures with different foaming agents and divalent metal ion, as well as examining its prospects in some practical applications. Chelating surfactants are functional molecules, with both surface active and chelating properties, which are water soluble and therefore suitable for chelation in many aqueous environments. The dual functionality offers the possibility to recover the chelating surfactant as well as the metals. The DTPA (diethylenetriaminepentaacetic acid)-based chelating surfactant 4-C12-DTPA (2-dodecyldiethylenetriaminepentaacetic acid) was synthesized at Mid Sweden University. In the absence of metal ions, all eight donor atoms in the headgroup of 4-C12-DTPA are titrating and the headgroup charge can be tuned from +3 to -5 by altering the pH. The solution properties, studied by surface tension measurements and NMR diffusometry, were consequently found strongly pH dependent. pH measurements of chelating surfactant solutions as a function of concentration was used to extract information regarding the interaction between surfactants in the aggregation process. Small differences in the conditional stability constants (log K) between coordination complexes of DTPA and 4-C12-DTPA, determined by competition measurements utilizing electrospray ionization mass spectrometry (ESI-MS), indicated that the hydrocarbon tail only affected the chelating ability of the headgroup to a limited extent. This was further confirmed in hydrogen peroxide bleaching of thermomechanical pulp (TMP) treated with 4-C12-DTPA. Interaction parameters for mixed systems of 4-C12-DTPA and different foaming agents were calculated following the approach of Rubingh’s regular solution theory. The mixtures were also examined with addition of divalent metal ions in equimolar ratio to the chelating surfactant. Strong correlation was found between the interaction parameter and the phase transfer efficiency of Ni2+ ions during flotations. Furthermore, a significant difference in log K between different metal complexes with 4-C12-DTPA enabled selective recovery of the metal ion with the highest log K. The findings in this study contribute to the understanding of the fundamental characteristics of chelating surfactants, which can be further utilized in practical applications.
12
Zhang, Xiang 1969. "Surfactant effects on the interaction of a three dimensional vortex pair with a free surface; and". Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/8234.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 2001.Includes bibliographical references.
In part I of the thesis, a canonical problem of three dimensional surfactant hydrody namics, the three-dimensional laminar interaction between a clean or contaminated free surface and a vortical flow underneath is considered. Initially, the vortical flow is in the form of two modulated finite-core vortex tubes parallel to the free surface. The vortex tubes break down via instability and helical vorticity is generated. The most prominent feature at the surface is that associated with the connection of helical vorticity to the free surface. For clean surface, the helical vorticity would interact fully with the free surface and reconnects to it under the influence of the primary vorticity. The presence of surfactant leads to substantial increase in the generation of free-surface secondary vorticity which results from large gradients in the surface surfactant distribution created by induced velocities at the free surface due to the primary vortex tubes. The secondary structure in the bulk interacts with the he lical vorticity, which totally alters the vortex pattern and connection process. The presence of contamination considerably weakens the connection in terms of strength, location and duration. The degree of secondary vorticity generation by the surfac tant is limited by a closed-loop interaction between the flow field (primary flow and secondary flow) and surfactant transport.
(cont.) The presence of secondary vorticity tends to smooth out the surfactant distribution on the free surface and consequently leads to a reduction in the generation of secondary vorticity itself associated with the sur factant gradient (together with surfactant diffusion). This negative feedback process and the rebounding of the primary vorticity by the secondary vorticity are the key processes underlying effects of insoluble surfactant. For contaminated free surface, the secondary and helical vortical structures interact strongly and new structures are generated. The split of helical vorticity because of the strong secondary vorticity leads to the new structures. When the surfactant is soluble, the effects are generally diminished due to the sorption kinetics between the surface and the bulk phase. Both vorticity isosurfaces and vortex filaments are used to describe vortex structures and their evolution. In Part II of the thesis, we investigated the turbulent flow over a smooth wavy wall undergoing traveling wave motion in the mean flow direction. Results are presented from direct numerical simulation with periodic and non-periodic streamwise boundary conditions. The Reynolds number in terms of mean velocity and motion wavelength is in the range of 3000-6500 and wave phase speed c relative to incoming flow velocity U is in the range of -0.5 and 2.0. The flow pattern is a strong function of c/U.For c = 0, there are features like separated region, attached boundary layer, and free shear layer ...
by Xiang Zhang.
Ph.D.
13
Groombridge, Matthew. "Fluid dynamics in nanoscale systems with amorphous surfaces and the interaction of nanoparticles with surfactant layers". Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/11145.
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The flow properties of fluids confined within nanoscale pores have been investigated. This study attempts to increase the understanding of some of the factors which affect flow over amorphous surfaces. Direct comparisons are made between experimental data and theoretical systems. Equilibrium and non-equilibrium methods are used to calculate the slip coefficient and a relaxation time, which is related to the interfacial friction. This is shown to be a simple and reliable way of predicting flow behaviour across a wide range of systems with different structures. Other methods, such as those based on Maxwell’s model, are found to be less reliable in systems with very rough surfaces. Enhanced flow rates, as found in some experimental systems, would have enormous benefits in a nanofluidic device. The flow dynamics in a variety of systems with different surface roughnesses and chemical compositions have been determined. The flow of water and decane fluids over a variety of carbon surfaces have been studied. Flow over PDMS surfaces with varying levels of oxidation has also been analysed. Enhancements are found to be lower than those predicted experimentally. There is a wide interest in the effects of inhalation of nanoparticles on lung tissues. In this work, the interactions of several environmentally interesting nanoparticles (fullerenes and titanium dioxide) with a model lung membrane have been simulated. The trajectories and interactions of the nanoparticles with the membranes are studied. Hydrophobic particles are found to sit amongst the lipid tails, hydrophillic particles nearer the water/lipid interface. Although no particles are found to cross freely into the water layer, an interesting effect is noted whereby water molecules are seen to leave the water phase of the membrane and coat the surface of hydrophilic nanoparticles. For the largest nanoparticles this creates a bridge across the membrane from the water phase to the vacuum.
14
Azar, Elise. "Interaction between inclusions mediated by surfactant membranes and changes in the local order of the acyl chains". Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS527/document.
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Pendant les dernières décennies les chercheurs ont étudié l'interaction entre des inclusions membranaires avec leur environnement et plus particulièrement avec la bicouche lipidique. On trouve dans la litérature beaucoup d'études théoriques et de simulations numériques sur ce sujet mais très peu d'expériences ont été menés là-dessus.Nous avons effectué des études systématiques afin de quantifier le potentiel d'interaction entre deux types d'inclusions au sein de la même couche et entre des couches adjacentes de plusieurs types de membranes ceci en variant surtout la concentration de particules dopantes, mais aussi d'autres paramètres pertinents : le type de tensioactif, l'épaisseur de la membrane, le contenu en cholestérol, la température, le degré d'hydratation. Pour cette fin nous avons utilisé la diffraction des rayons X aux petits angles et nous avons constaté que le potentiel d'interaction peut être décrit par une exponentielle décroissante en fonction de la concentration et de la température d'inclusion et qu'il dépend largement de la teneur en cholestérol et du degré d'hydratation.D'autre part, nous avons étudié l'effet de la gramicidine, un peptitde membranaire, sur l'ordre local des chaînes acyles de lipides et de tensioactifs. Cette étude a été menée en utilisant deux techniques différentes: en premier lieu la résonnance magnétique nucléaire, (DROSS-NMR) qui permet de détecter le changement d'ordre dans l'orientation des chaînes acyles, et en second lieu par diffraction des rayons X aux grands angles afin de déterminer le changement d'ordre dans la position des chaînes acyles. Nous avons trouvé que le dopage de la gramicidine dans les membranes rigidifie les chaînes acyles et dans un cas aussi les têtes polaires et en plus induit une modification de l'ordre local de ces chaînesFor years scientists have been studying the interaction of membrane inclusions with their environment and more particularly with the lipid bilayer.This field has been based on theoretical approaches and numerical simulation and lack experiments.We performed systematic studies in order to quantify the interaction potential between two types of inclusions within the same layer and between adjacent layers in several kinds of membranes and tried to elucidate the influence of the relevant parameters: the type of lipids or surfactants, the cholesterol content, the hydration degree, the type of inclusions and the membrane thickness using small-angle X-ray scattering. We found that the interaction potential can be described by a decreasing exponential as a function of inclusion concentrations and temperature and depends largely on the cholesterol content and hydration degree.On the other hand, we also studied the effect of the peptide inclusions on the local order of lipid and surfactant acyl chains using two different techniques: DROSS-NMR technique to detect the changes in the orientational order and WAXS technique to detect the changes in the positional order of the acyl chains. We found that inserting these peptides inclusions within the membrane rigidifies the acyl chains and sometimes even the headgroups and modifies their local order
15
Ahmed, Abdul Salim. "Structural studies of the interaction of bacterial lipopolysaccharides with C-reactive protein and lung surfactant protein D". Thesis, Keele University, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.572426.
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In this thesis, recognition of the complex natural ligand lipopolysaccharide (LPS) by the innate immune proteins C-reactive protein (CRP) from Limulus polyphemus (Atlantic horseshoe crab), and human surfactant protein D, in the form of a recombinant fragment comprising the a-helical coiled-coil neck plus three lectin domains (CRD), has been studied using X-ray crystallography. The intact LPS from three bacteria, E. coli (0111.B4), P. aeruginosa (serotype 10) and H influenzae type b strain RM153 Eagan (wild type and 4A mutant), were subjected to mild acid hydrolysis to separate the lipid A from the extended oligosaccharide fraction (OS) to improve solubility in crystallisation studies. X-ray diffraction data collection using synchrotron radiation on crystals of Limulus CRP grown in the presence of intact E. coli LPS provided diffraction to 2.oA resolution showing a large unit cell with multiple copies of the molecular aggregate of unknown size in the asymmetric unit. Structure solution was not attempted but has since been achieved by other members of the research group although significant difficulties remain with the refinement. Crystallographic analysis at 1.7 A resolution of the recombinant fragment of human SP-D crystals with H influenzae Eagan wild type and Eagan 4A OS shows no binding of the Eagan wild type OS, however, the Eagan 4A OS ligand is found complexed to the protein . CRD in chains Band C in a calcium dependent manner. No ligand binding could be observed in chain A. In both chains the binding is found in one orientation involving the core L,D-heptose C6- and Cr hydroxyl groups of the glycerol side chain, despite the availability of a terminal core glucose bearing vicinal equatorial C3 and C4 hydroxyl groups. Interaction with Kdo, seen in a putative anyhydro closed 5-membered ring form, is also evident suggesting that efficient recognition requires multiple binding interactions.
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Abozaid, Suhair Mohamed. "Studies on the interaction of surfactant protein SP-D with Inflenza A virus, Aspergillus fumigatus and dendritic cells". Thesis, Brunel University, 2016. http://bura.brunel.ac.uk/handle/2438/13595.
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Surfactant proteins, SP-A and SP-D, are collagen-containing calcium-dependent (C-type) lectins, called, collectins. Their primary structure has four regions: a cysteine-linked N- terminal region involved in multimerization, a collagen region composed of Gly-X-Y repeats, coiled-coil neck region, and the C-terminal carbohydrate recognition domains (CRD) or C-type lectin domain. SP-A looks like a bouquet, while SP-D is a cruciform- like structure, with four arms of equal length. SP-A and SP-D have been shown to act as innate immune molecules at pulmonary as well as extra-pulmonary sites by binding to pathogens, allergens and apoptotic/necrotic cells via their CRD region. SP-A and SP-D can induce pathogen neutralization and enhanced phagocytosis. In addition, SP-A and SP-D can interact via CRDs with allergens and dampen allergic reaction in vitro and in vivo. This thesis examines in vitro interaction of a recombinant fragment of human SP-D containing neck and CRD regions (rhSP-D) with IAV and Aspergillus fumigatus, in addition to characterizing a dichotomy of the effects of SP-A and SP-D on dendritic cells in an attempt to explain how SP-A and SP-D modulate DC functions differentially. Experiments involving interaction of rhSP-D with IAV pandemic strain show that it can be a restrictive factor against the virus, in addition to modulating immune response by a macrophage cell line. The rhSP-D can have anti-A. fumigatus effect directly and indirectly in the context of pathogen as well as allergen. A comparison has been made between two recombinant fragments of SP-D that have been expressed with and without 8 Gly-X-Y repeats for their fungistatic properties. The effects of SP-A and SP-D on cultured DC maturation, and effector cytokine and proliferative response of co-cultured cells have also been examined in vitro.
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Wang, Xiang. "Study of electrostatic interaction between charged surfactant vesicles and ionic molecules by bulk and fluorescence correlation spectroscopy measurements". College Park, Md. : University of Maryland, 2007. http://hdl.handle.net/1903/7606.
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Thesis (Ph. D.)--University of Maryland, College Park, 2007.Thesis research directed by: Dept. of Chemistry and Biochemistry. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Fowler, William Mackenzie. "Interaction of selected fungicides with insoluble bovine skin collagen in the presence of the non ionic surfactant Triton X-100". Thesis, Rhodes University, 1992. http://hdl.handle.net/10962/d1004976.
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In the leather industry fungicides are often used for the protection of wet-blue leather. These fungicides are usually only sparingly soluble and are therefore formulated together with surfactants in order to increase their solubility and to ensure an even distribution over the surface of the hide after treatment. Solutions containing both fungicides and surfactant are complex. The nature of these solutions was investigated. By means of UV/Vis spectroscopy and viscometry it was shown that the surfactant and fungicides form micelles and mixed micelles in solution. The nature of these micelles and mixed micelles was dependent on the solution temperature as well as on the concentrations of the surfactant and fungicides. At the higher temperatures and concentrations transition to large, possibly rod-shaped, mixed micelles occurred. The interaction between the selected fungicides 2-(thiocyanomethylthio)benzothiazole and n-octyl-4-isothiazol-3-one with bovine skin collagen in the form of both limed and lightly chromed hide powder in the presence of the non ionic surfactant Triton X -100 was investigated. Fungicide uptake was determined by difference measurements on the float solutions at regular intervals during treatment. Binding was rapid with equilibrium being established within the first six hours even for the solutions with the highest surfactant concentration. Binding failed to follow a normal mass-action binding-type isotherm approaching a saturation limit, but increased continuously indicating a co-operative effect whereby binding site affinity actually increased with the amount of ligand bound. Binding was accompanied by a drop in the free surfactant in the solution at the higher biocide levels indicating the formation of complex mixed micelles which bind to the collagen fibres. The uptake and antifungal activity of commercial fomulations of the fungicides on chrome-tanned wet-blue leather was investigated at various treatment temperatures. At lower fungicide treatment concentrations, binding tended to follow a typical mass-action type binding isotherm, increasing slightly with temperature. At higher float concentrations, an inflexion point was apparent beyond which uptake showed a marked increase with concentration. This inflexion point, signifying a change in binding characteristics, occurred at progressively lower concentrations with increasing temperature. Antifungal activity in terms of storage periods to onset of fungal growth was determined on the wet-blue leather cuttings immediately after treatment and drainage and also on sample discs after exhaustive extraction of free fungicide using dichloromethane. Storage performance testing of the various treated wet-blue leathers was carried out by different methods. Residual protective periods showed a curvilinear increase with dosage offer and surface uptake. In the low dosage range treatment temperature had only a relatively slight effect in promoting uptake and improving storage protection. At higher dosages, the influence of temperature on uptake and storage protection was greater due to the increase in surface binding of the fungicides at the elevated temperatures. Only a portion of the fungicide uptake was recovered by direct solvent extraction of the treated wet-blue leather. Solvent extraction reduced storage margins. The storage response in relation to fungicide content was, however comparable after extraction, indicating that both irreversibly bound and physically associated fungicide offered effective protection. Results of the study provide further insight into the mode of interaction of fungicide emulsion dispersion with bovine skin collagen, and the importance of the emulsion dispersions and its stability in determining the uptake of fungicide.
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Iruthayaraj, Joseph. "Poly (ethylene oxide) based bottle-brush polymers and their interaction with the anionic surfactant sodium dodecyl sulphate : solution and interfacial properties /". Doctoral thesis, Stockholm : Kemi, Chemistry, Kungliga Tekniska högskolan, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4680.
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CHAVARRIA, HELMUT ISAAC PADILLA. "MOLECULAR DYNAMICS OF THE INTERACTION OF DIBENZ[A,H]ANTHRACENE AND ITS METABOLITE WITH MODELS OF CELL MEMBRANE AND LUNG SURFACTANT". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2014. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=25054@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
O estudo da interação de dibenzo[a,h]antraceno (DBahA) e de seu metabólito com modelos de membrana celular e surfactante pulmonar foi realizado através de dinâmica molecular. Os modelos de membrana celular e de surfactante pulmonar são geralmente misturas de dipalmitoil fosfatidilcolina (DPPC), dipalmitoil fosfatidilglicerol (DPPG), e colesterol. No caso do modelo de surfactante pulmonar pode ser incluido as proteínas surfactantes (SP-A, SP-B, SP-C e SP-D). Neste projeto, o dibenzo[a,h]antraceno (DBahA) foi simulado com o DPPC sozinho e com uma mistura 32/32/1 de DPPC/DPPG/Colesterol. DBahA é encontrado nos gases de exaustão de veículos automotores (especialmente os movidos a diesel), na fumaça do cigarro e da madeira, além de alimentos grelhados na brasa. Ele é capaz de ser metabolizado pelo citocromo P450 e seu metabólito interage com o DNA, sendo então mutagênico e altamente carcinogênico. Os principais resultados mostram que o DBahA se difunde para o interior dos modelos e forma aglomerados. Quando o DBahA está em concentração elevada na parte exterior dos modelos, este não consegue se difundir facilmente para o interior dos modelos na escala de tempo simulado e forma aglomerados na interface água/modelo. O metabólito age similarmente, no entanto prefere ficar mais próximo da cabeça polar dos modelos.
The study of the interaction of dibenz[a,h]anthracene (DBahA) and its metabolite with cell membrane and pulmonary surfactant models was performed by molecular dynamics. The cell membrane and pulmonary surfactant models usually are mixtures of dipalmitoyl phosphatidylcholine (DPPC), dipalmitoyl phosphatidylglycerol (DPPG), and cholesterol. In the case of pulmonary surfactant, the models may include surfactant proteins (SP-A, SP-B, SP-C and SP-D). In this project, the DBahA was simulated with DPPC and with a 32/32/1 mixture of DPPC/DPPG/Cholesterol. DBahA is found in automotive vehicles (especially diesel vehicles), in cigarette and wood smoke, and grilled food. The DBahA molecule is metabolized by cytochrome P450 and its metabolite interacts with DNA, being mutagenic and highly carcinogenic. The results show that the DBahA diffuses into the interior of the models forming clusters. In the simulated time scale, when the DBahA is in high concentration in the outer part of the models, it may not spread easily to the inner side of the models because it forms clusters in the water/model interface. The metabolite acts similarly, but prefers to stay closer to the polar head of the models.
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Kovářová, Lenka. "Studium fyzikálních gelů s hydrofobními doménami". Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2013. http://www.nusl.cz/ntk/nusl-216963.
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The thesis is focused on physical hyaluronan gels. The object of study is the interaction of hyaluronan (HyA) with oppositely charged surfactants in physiologic solution (0.15 M NaCl), leading to the formation of gel. In the first part of work have been determined the solids´ contents (X) in gels and their supernatants in percentage and their correlation with molecular weight concentration of original HyA solution and the ratio of binding sites on hyaluronan chain and surfactant CTAB. To conclude, decrease in HyA concentration results in higher values of X and vice versa. On the other hand, increase in the value of X with increasing molecular weight of HyA is not so significant. Analogous conclusions have been made for supernatants and the amount of solids in gel. Drying process has been recorded by drying curves. Swelling process has been used for the characterization of gels. The percentage of water that can be absorbed by dried gel, was determined. The results are in agreement with the measurements of solids´ content in gels. In the next part, the correlation between rheological properties of gels and HyA concentration, HyA molecular weight and concentration of CTAB have been studied by the oscillation and flow tests. The samples with the highest molecular weight and concentration have the most viscoelastic character. The flow test confirmed the assumed pseudoplastic behavior of gels. A very interesting trend arose while comparing HyA concentrations and viscosity in stock solutions and gels. Whereas in stock solution viscosity (at low shear rate) is lower with increasing of HyA concentration, the situation was exactly the opposite in gels. The results are in agreement with frequency tests and observed character of gels.
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Valstar, Ank. "Protein-surfactant interactions". Doctoral thesis, Uppsala University, Department of Physical Chemistry, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-1070.
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Protein-surfactant interactions in aqueous media have been investigated. The globular proteins lysozyme and bovine serum albumin (BSA) served as model proteins. Several ionic and non-ionic surfactants were used.
Fluorescence probe measurements showed that at low sodium dodecyl sulfate (SDS) concentration (< 0.1 M) one micelle-like SDS cluster is bound to lysozyme. From dynamic light scattering (DLS) results it was observed that lysozyme in the complex does not correspond to the fully unfolded protein. At high SDS concentration (> 0.1 M) one compact and one more extended lysozyme-SDS complex coexist.
The influence of surfactant alkyl chain length and headgroup on BSA-surfactant complex formation was investigated. In these studies, binding isotherms were determined by nuclear magnetic resonance (NMR), DLS was used to measure the hydrodynamic radii of the complexes and the size of the micelle-like aggregates on BSA was determined using fluorescence probe methods.
It was observed from fluorescence measurements that the number of bound SDS molecules does not depend on the presence of the disulfide bridges. Reduced proteins wrap more efficiently around the micelle-like structures, resulting in somewhat smaller complexes, as observed with DLS.
Concentrated BSA-SDS solutions and the corresponding heat-set gels were investigated using DLS and fluorescence probe methods. Correlation lengths in the gel were determined and it was concluded that SDS forms micelle-like aggregates on BSA in concentrated solution and gel phase. The gel region in the ternary phase diagram BSA-SDS-3.1 mM NaN3 has been determined at room temperature.
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Raw, Juliana. "Estudo da interação de líquidos iônicos com proteínas modelo". Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-22112016-153329/.
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Líquidos iônicos (LIs) são sais que se encontram no estado líquido em temperaturas menores que 100ºC e que vêm ganhando protagonismo na área chamada química verde, prometendo: substituir solventes nocivos ao meio ambiente, aprimorar componentes eletrônicos, favorecer biocatálises dentre outros. Sua alta estabilidade e baixa toxicidade são frequentemente afirmadas, porém, devem ainda ser melhor investigadas. Com o objetivo de implementar o entendimento da interação dos líquidos iônicos com sistemas de relevância biológica, realizamos um estudo sistemático acerca da interação de 3 diferentes líquidos iônicos anfifílicos de mesma cabeça polar e diferentes caudas carbônicas ([C10mim][Cl], [C12mim][Cl] e [C14mim][Cl]) com 3 diferentes proteínas modelo, através das técnicas de absorção óptica, fluorescência, dicroísmo circular (CD) e espalhamento de raios-X a baixos ângulos (SAXS). Para Tanto, utilizamos as proteínas BSA e HSA (Albuminas de Soro Bovino e Humano, respectivamente) além da lisozima. Observamos a supressão da fluorescência das proteínas em todos os casos analisados, onde a diminuição da intensidade correspondeu a, para as proteínas BSA, HSA e lisozima, respectivamente, (55±3)%, (16.1±0.8)% e (4.1±0.2)%, em presença de 0.6mM de [C14mim][Cl], (38±2)%, (13.2±0.7)% e (0.6±0.1)% em presença de 0.6mM de [C12mim][Cl] e (11.0±0.5)%, (9.2±0.5)% e (0.0±0.1)% em presença de 0.6mM de [C10mim][Cl]. Os espectros de absorbância e fluorescência de todos os sistemas nos indicam uma interação de contato entre as proteínas e os líquidos iônicos. Constatamos também o deslocamento do pico de fluorescência, das proteínas BSA e HSA, para menores comprimentos de onda (blue-shift), na medida em que a concentração de LI era aumentada. O máximo deslocamento () alcançado correspondeu a (21±1)nm para ambas albuminas, enquanto que a lisozima não apresentou deslocamento significativo. O blue-shift pode ser explicado pela aproximação das cadeias carbônicas e formações de pontes de hidrogênio nas proximidades dos triptofanos. De acordo com a técnica de SAXS, evidenciamos o aumento do raio de giro das proteínas, na medida em que adicionamos LIs. O raio de giro da BSA, da HSA e lisozima em ausência de LI são (29±1)Å, (30±1)Å e (15±1)Å, respectivamente, e passam para (46±1)Å, (44±1)Å e (20±1)Å respectivamente, em presença de 0.6mM de [C14mim][Cl]. As curvas de SAXS também apresentaram o indício da formação de estruturas micelares a partir de uma dada concentração. Além da alteração em sua estrutura terciária, os dados de CD indicam uma leve perda de estrutura secundária de ambas as albuminas (BSA e HSA), passando de 80 para 65% de -hélice em ausência e presença de 0.6mM de [C14mim][Cl], respectivamente. Sugerimos que as interações das proteínas com os líquidos iônicos, embora inicialmente movidas por forças eletroestática, possuem como principal fator o efeito hidrofóbico, portanto quanto maior a cadeia carbônica do LI maior é sua interação com a proteína. Tal interação causa o desenovelamento das proteínas e formação de um complexo e estruturas micelares a altas concentrações de LI. Acreditamos que este trabalho traz novas informações acerca da interação dos LIs com proteínas modelo, indicando sua capacidade de alterar a conformação das mesmas.Ionic liquids (ILs) are salts that are liquid at temperatures smaller than 100 ° C and are gaining prominence in the so-called green chemistry, promising: replace harmful solvents to the environment, improve electronic components, and favor biocatalysis, among others. Its high stability and low toxicity are often asserted; nevertheless, they are ascribed to ILs due to its small volatility. With the aim of improving the understanding of the interaction of ILs with biological relevant systems, we conducted a systematic study of the interaction of three different ionic liquids of the same polar head and different paraffinic tails ([C10mim][Cl], [C12mim][Cl] and [C14mim][Cl]) with three different model proteins, through the techniques of optical absorption, fluorescence, circular dicrhoism (CD) and small angle X-ray scattering (SAXS). To do so, we use BSA and HSA proteins (Bovine Serum Albumin and the Human Serum Albumin, respectively) and lysozyme. We observed fluorescence quenching, of all studied proteins, where the decrease in the fluorescence was (for BSA, HAS and lysozyme, respectively): (55 ± 3)%, (16.1 ± 0.8)% to (4.1 ± 0.2 )% in the presence of 0.6mm [C14mim][Cl], (38 ± 2)%, (13.2 ± 0.7)% to (0.6 ± 0.1)% in the presence of 0.6mm [C12mim][Cl] and ( 11.0 ± 0.5)% (9.2 ± 0.5)% and (0.0 ± 0.1)% in the presence of 0.6mm [C10mim][Cl]. UV-vis absorbance spectra and fluorescence indicate all systems in a contact interaction between proteins and ionic liquids. We also note the shift of the fluorescent peak of BSA and HSA proteins for shorter wavelengths (blue-shift), as the IL content was increased. The maximum shift () achieved corresponded to (21 ± 1) nm for both albumins, whereas no significant displacement was observed for lysozyme. The blue-shift can be explained by the approach of carbon chains and formation of hydrogen bonds in the vicinity of tryptophan. SAXS data indicate an increasing in the proteins radius of gyration value as ILs was added in the solution. The turning radius of BSA, HSA and lysozyme in the absence of IL are (29 ± 1) Å, (30 ± 1) Å and (15 ± 1) Å, respectively, and go to (46 ± 1) Å, ( 44 ± 1) Å and (20 ± 1) Å, respectively, in the presence of 0.6mm [C14mim][Cl]. The SAXS curves also show evidence of the formation of micellar structures from a given concentration. Besides the change in its tertiary structure, the CD data indicates a slight loss of secondary structure of both albumins (BSA and HSA), from 80 to 65% of -helix in the absence and presence of 0.6mm [C14mim][Cl], respectively. We suggest that the interactions of the protein with the ionic liquid, although initially driven by electrostatic forces, have a major factor hydrophobic effect and thus the higher the carbon chain of greater IL is its interaction with the protein. This interaction causes unfolding of the protein and formation of a micellar structures at high concentrations of IL. We believe this work provides new information about the interaction of ILs with model proteins, indicating its ability to alter the conformation of the same.
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Šejnohová, Michaela. "Studium interakcí hyaluronan-tenzidy dialyzační technikou". Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2014. http://www.nusl.cz/ntk/nusl-217017.
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This diploma thesis is concentrated on the interactions between polyelectrolyte (hyaluronan) and cationic surfactant (CTAB). The experiments were performed in an aqueous solution and in an environment of physiological ionic strength (0,15mmoldm-3 NaCl). The determination of the surfactant concentration in solutions was based on the formation of colored complexes of CTAB and picric acid in chloroform. The concentrations of surfactant were measured by UV-VIS spectroscopy. The stability of CTAB+HyA was examined by a dialysis method. The results showed that, regardless of the environment, the presence of HyA in solution reduces the number of free molecules of CTAB which can be determined in the sample. It has been proved that there is an interaction between HyA and surfactant and that CTAB has greater affinity for HyA then for the picric acid. The stability of CTAB+HyA was determined by dialysis of 120 hours. After that time, the concentrations of the retentate and permeate were settled. The results showed that in the membrane remains a certain amount of CTAB bounded to hyaluronan. The system can be suitable for the preparation of targeted carriers of biologically active substances.
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Mears, Sarah Jane. "Polymer, particle, surfactant interactions". Thesis, University of Bristol, 1996. http://hdl.handle.net/1983/50736698-01b4-4c84-bc85-7f94e411a6f2.
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Patel, Rajesh. "Studies of drug-surfactant interactions". Thesis, University College London (University of London), 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313319.
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White, Sarah Jayne. "Polymer surfactant interactions in gels". Thesis, University of Bristol, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385970.
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MacNab, Jamie Robert. "Interaction of oils with surfactants". Thesis, University of Hull, 1996. http://hydra.hull.ac.uk/resources/hull:4703.
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This thesis is concerned with the interactions of oils with surfactants. The understanding of these interactions is important for a number of practical applications which include perfume delivery in fabric softeners. Both non-ionic surfactants, of the general formula H( CH2)n( OCH2CH2)m-OH, and lome surfactants, of the general formula CnH2n+lW(CH3)3Br were used in the study. Oils of varying polarity were investigated from non-polar alkane oils to moderately polar perfume oils.Initially, the work of adhesions of the perfume oils with water were studied to establish where these oils 'fitted-in' to a range of oils of varying polarity. It was found that the three perfume oils studied (linalool, cineole and eugenol) all exhibited adhesion properties which were fairly typical of moderately polar oils. In order to obtain the enthalpies and entropies of adhesion of the perfume oils with water the surface tensions and interfacial tensions with water were measured as a function of temperature. The enthalpy of adhesion for linalool with water is consistent with values obtained for the enthalpy of hydration of the hydroxyl group.The co-surfactant nature of the perfume oils was investigated by tension measurements of their adsorption to the heptane-water interface. Linalool and eugenol show reasonably high surface activity at this interface and could therefore be expected to act as cosurfactants in systems that contain conventional surfactants.The phase behaviour of the CgE5 + water + octane micro emulsion system was investigated to determine the effect of adding different concentrations of perfume oil on the size, shape and position of the three phase region. It was found that linalool reduces the size of this three phase region and also reduces the temperature at which the three phase region occurs. Although not conclusive, this behaviour suggests the system is approaching a triclitical point.It is of interest also to understand the adsorption of oils at planar surfactant mono layers and then attempt to relate the adsorption data to bulk phase solubilisation of the oils in micelles. The adsorption at a planar interface was attained by measuring the surface pressure of the oil at different activities. The surface concentration of the oils was then calculated from the Gibbs adsorption equation. By measuring these surface pressures as a function of activities at various temperatures, it was possible to derive the adsorption enthalpies and entropies with use of a form of the Van't Hoff equation. It was found that alkane adsorption increases with decreasing alkane chain length and the isotherms show a greater curvature upwards for the shorter chain length alkanes suggesting that the adsorption becomes more favourable as more alkane is added to the mixed alkane/surfactant film.Headspace analysis was employed to measure the solubilisation of oils in bulk surfactant solutions. The results obtained with this technique were preliminary although early indications suggest that more alkane oil is solubilised in bulk aggregates with curved monolayers than is adsorbed at planar monolayer interfaces. However, solubilisation of oil in bulk solutions may either be in the curved monolayer or they could form a 'core' of oil inside the aggregate.
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Hirst, Natasha C. "Solvency effects on polymer-surfactant interactions". Thesis, Cardiff University, 2008. http://orca.cf.ac.uk/54690/.
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Surfactants and polymers have extensive uses and applications in day to day life as detergents, cosmetics, and paints, and in industry, medicine and pharmaceuticals. Gaining a comprehensive understanding of the properties and functions of surfactant and polymer systems in a range of solvents will support the continued development of new uses for these systems. Against this background, this study characterised the interaction of the anionic surfactant sodium dodecyl sulphate (SDS) with the nonionic polymer, poly(vinylpyrrolidone) (PVP) in ethanol/water mixtures. A wide range of techniques were used, including surface tension, fluorescence spectroscopy, Nuclear Magnetic Resonance, Electron Paramagnetic Resonance, Small-Angle Neutron Scattering, and viscometry. This enabled properties such as the, critical micelle concentration and critical aggregation concentration (or CMC1) to be determined, as well as measuring the size and shape of micelles formed and of polymer configurations and further establishing trends in these physical properties with solvent composition. The study then went on to investigate SDS with a non-ionic triblock copolymer, Pluronic P104, in ethanol/water mixtures. This was a more challenging system and yielded some preliminary results, setting the way for further work on the interactions of ethanol with pluronics and surfactants.
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Berge, Johanna. "Interactions between surfactant mesophases and nanoparticles". Thesis, University of Bristol, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.705472.
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Perrins, N. M. "Interactions in surfactant stabilised colloidal micro-systems". Thesis, University of Kent, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.353999.
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Pynn, Christopher John. "Probing molecular interactions of a phospholipid surfactant". Thesis, University of Southampton, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.436971.
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SOARES, Deyze Alencar. "Ação da fosfolipase B extracelular de Paracoccidioides brasiliensis na interação ex vivo com macrófagos alveolares". Universidade Federal de Goiás, 2010. http://repositorio.bc.ufg.br/tede/handle/tde/1296.
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Previous issue date: 2010-03-26Paracoccidioides brasiliensis, a thermodimorphic fungus, is the causative agent of the most prevalent systemic mycosis in Latin America, paracoccidioidomycosis. The phospholipase B (PLB) enzyme is considered an important virulence factor in this dimorphic fungus, involved in the immune response of the host-pathogen interaction. Our objective was to determine whether a P. brasiliensis (Pb18) PLB is involved in adhesion / internalization of yeast and evasion of host immune responses. The effect of PLB was analysed using specific inhibition of PLB (alexidine dihydrochloride) and pulmonary surfactant in an ex vivo model (Pb18) of alveolar macrophage (MHS cells) infection. PLB enzyme assays and real time RT-PCR (qRTPCR) analysis of genes differentially expressed in the process of evasion: plb1 (phospholipase B1), icl1 (isocitrate lyase) and sod3 (Cu, Zn dismutase) and immune responses: clec2 (C-type lectin domain 2), cd14 (cluster of differentiation 14), tlr2 (toll-like receptor 2), nfkb (nuclear factor kappa B), nkrf (NF-kappaB repressing factor), il1β (inteleukin-1β) and tnfα (tumor necrosis factor alpha) were carried out using selective inhibition of PLB activity and pulmonary surfactant. The levels of cytokines inteleukin 10 (IL-10), IL-12 and TNF-α) were also determined by ELISA. PLB activity under adhesion conditions of P. brasiliensis (Pb18) to alveolar macrophage cells was found at high levels up to 6 hours post-infection. In the conditions of exposure to pulmonary surfactant and alexidine dihydrochloride, PLB activity and the level of transcripts of genes related to phagocytosis and inflammatory response were measured. We found that PLB activity had an influence on the phagocytic activity of alveolar macrophages. Alexidine dihydrochloride (0,25 μM) selectively inhibited PLB activity by 66% and decreased significantly the adhesion and internalization of yeast on MHS cells. Genes involved in phagocytosis (trl2 and cd14) and inflammatory response (nrkf, tnfα and il1β) were down-regulated in the presence of the PLB inhibitor. In contrast, the PLB activity and internalization of fungal yeast cells increased significantly in the presence of pulmonary surfactant (100 μg/mL) and genes such as clec2, important for effective phagocytosis by MHS cells, and the pro-inflammatory inhibitor (nkrf) were up-regulated. Also, the pulmonary surfactant did not alter cytokine production, while alexidine dihydrochloride decreased the levels of IL-10 and increased the levels of IL-12 and TNF-α. In addition, through simultaneous analyses of gene expression for the pathogen, P. brasiliensis, we found upregulation of the genes sod3, icl1 and plb1, required for the evasion of alveolar macrophages. P. brasiliensis PLB is important for the binding and internalization of yeast at macrophage surfaces. The specific effect of inhibiting PLB enzyme activity indicates that adhesion may be facilitated indirectly via fatty acid release from phospholipids of the membrane of host cells. This is the first study to show that PLB activity may modulate immune responses to P. brasiliensis infection.
Paracoccidioides brasiliensis, fungo dimórfico, é o agente etiológico principal micose sistêmica da América Latina, paracoccidioidomicose. A enzima fosfolipase B (PLB) é considerada um importante fator de virulência nesse fungo dimórfico e está envolvida na resposta imune da interação patógeno-hospedeiro. Nosso objetivo foi determinar se a PLB de P. brasiliensis (Pb18) está envolvida na adesão e internalização de leveduras e na evasão da resposta imune hospedeira. O efeito da PLB foi analisado usando o inibidor seletivo de PLB (alexidine dihydrochloride) e o surfactante pulmonar (Survanta) em um modelo ex vivo de infecção de macrófagos alveolares (MHS) com Pb18. Ensaio enzimático de PLB e análise de genes diferencialmente expressos por RT-PCR em tempo real (qRT-PCR) no processo de evasão: plb1 (fosfolipase B1), icl1 (isocitrato liase) e sod3 (Cu, Zn dismutase); e na resposta imune: clec2 (lecitina tipo-C 2), cd14 (cluster de diferenciação 14), tlr2 (receptor toll-like 2), nfkb (fator nuclear kappaB), nkrf (repressor fator nuclear kappaB), il1β (interleucina- 1 beta) e tnfα (fator de necrose tumoral alfa) foram realizados usando o inibidor seletivo da atividade de PLB e surfactante pulmonar. Os níveis de citocinas interleucina 10 (IL-10), IL-12 e TNF- α) foram determinados por ELISA. A atividade de PLB usadas em baixas condições para a adesão de P. brasiliensis (Pb18) obteve altos níveis em 6 horas pós-infecção. Na presença do surfactante pulmonar e alexidine dihydrochloride, a atividade da PLB e os níveis de transcritos dos genes relacionados à fagocitose e à resposta inflamatória foram quantificados. A PLB teve influência na atividade fagocítica dos macrófagos. Alexidine dihydrochloride (0,25 μM) inibiu seletivamente a atividade PLB em 66% e diminuiu significativamente a adesão e internalização de leveduras por macrófagos alveolares (MHS). Genes envolvidos na fagocitose (trl2 e cd14) e resposta inflamatória (nrkf, tnfα e il1β) foram reprimidos na presença do inibidor de PLB. Em contraste, a atividade PLB e internalização de leveduras aumentou significativamente na presença do surfactante pulmonar (100 μg/mL) e genes assim como clec2, importante para uma fagocitose efetiva pelos macrófagos alveolares (MHS), e o inibidor pró-inflamatório (nkrf) foram induzidos. Entretanto, o surfactante pulmonar não alterou a produção de citocinas, enquanto que alexidine dihydrochloride diminuiu os níveis de IL-10 e aumentou os níveis de IL-12 e TNF-α. Em adição, nas análises simultâneas de expressão de genes, P. brasiliensis, houve indução dos genes sod3, icl1 e plb1, requeridos para a evasão dos macrófagos alveolares. A PLB de P. brasiliensis é importante na adesão e internalização de leveduras pelos macrófagos alveolares. O efeito específico da inibição da atividade da PLB indica que a adesão pode ser facilitada indiretamente via liberação de ácidos graxos dos fosfolipídeos de membrana das células hospedeiras. Esse é o primeiro estudo mostrando que a atividade da PLB pode modular a resposta imune à infecção pelo P. brasiliensis.
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Brew, Henry. "An equilibrium study of polyelectrolyte/surfactant/dye interactions". Thesis, University of Salford, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272695.
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Alexander, P. H. V. "Solution-membrane interactions by non-ionic surfactants". Thesis, Cardiff University, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304749.
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Li, Jing. "Processing, stability and interactions of lung surfactant protein C /". Stockholm, 2005. http://diss.kib.ki.se/2005/91-7140-582-8/.
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Warren, Nicola. "A study of polymer-surfactant interactions by neutron reflectivity". Thesis, University of Oxford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365840.
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Woskett, Christine Maria. "Competitive adsorption and protein-surfactant interactions in food emulsions". Thesis, University of Leeds, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235613.
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He, Yunfei. "Study on the interfacial properties of surfactants and their interactions with DNA". Thesis, Paris 11, 2013. http://www.theses.fr/2013PA112112/document.
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Ayant une partie hydrophile et une partie hydrophobe, les tensioactifs peuvent s'adsorber sur des interfaces et d'abaisser la tension interfaciale (γ), ce qui améliore les propriétés interfaciales. Tensioactifs chargés sont également utilisés dans des applications biologiques, par exemple dans la livraison de gènes. Dans cette thèse, nous avons étudié les propriétés d'adsorption des tensioactifs, à la fois aux interfaces air/eau et sur l'ADN pour former des complexes.La première partie de la thèse se concentre sur les études d'interface de tensioactifs. Pour comprendre comment ils fonctionnent dans ces applications, il est important de connaître les échelles de temps de l'adsorption et la désorption de surfactant. Ainsi, il est nécessaire d'étudier l'adsorption et la cinétique de désorption, qui sont déjà largement étudié. Cependant, les études traditionnelles ont tendance à faire de nombreuses hypothèses, par exemple, l'extension de l'applicabilité des relations d'équilibre à des cas de non-équilibre. Dans cette mémoire, l'adsorption des deux systèmes tensioactifs différents a été étudiée, C12E6 de tensioactif non ionique et d'agent tensio-actif ionique CTAB avec suffisamment de sel. Une mesure de la compression de la bulle unique combiné avec une tension superficielle d'équilibre connue (γeq) de valeur permet de déterminer γ(Γ), ce qui est plus précis que les résultats des méthodes traditionnelles. Les concentrations de surface en fonction du temps sont mesurés, ce qui montre que l'adsorption est contrôlée par la diffusion à temps courts.Après avoir montré que l'adsorption est contrôlée par diffusion, nous rapportons la désorption des tensioactifs à partir de l'interface air/eau pour différents systèmes. Les processus de désorption sont confirmées pas être purement limitée par diffusion, indiquant la présence d'une barrière d'énergie. La barrière d'énergie est influencée par la longueur de la chaîne alkyle, et non le type de contre-ion.Dans la deuxième partie de la thèse, nous nous concentrons sur les systèmes d'ADN/tensioactif. Bien que l'interaction entre les tensioactifs cationiques et anioniques polyélectrolyte a été largement étudiée, il reste nécessaire de mieux comprendre le système complexe, en particulier pour rationaliser le choix des tensioactifs pour atteindre une capacité de liaison de l'ADN contrôlable et une faible toxicité pour l'organisme. Dans cette thèse, nous avons lancé l'enquête systématique sur les interactions des deux tensioactifs cationiques avec l'ADN.Le premier tensioactif utilisé est un gemini tensioactifs cationiques 12-2-12∙2Br. Avant de l'utiliser avec l'ADN d'une caractérisation approfondie a été effectuée. L'équilibrage du 12-2-12∙2Br sur une interface air/eau en l'absence d'électrolyte est très lent. Ajout de NaBr affecte peu la cinétique d'adsorption à des temps courts, pendant lesquels l'adsorption de diffusion. Cependant, l'adsorption s'équilibre beaucoup plus rapide. La formation de micelles de tensioactif cationique gemini 12-3-12∙2Br a été étudiée. La concentration micellaire critique (CMC) augmente légèrement avec la température et diminue avec la force ionique. 12-3-12∙2Br interagit fortement avec l'ADN, en raison de l'attraction électrostatique entre les deux et les interactions hydrophobes entre les chaînes alkyles. Sel écrans l'attraction électrostatique, tout en augmentant la longueur d'écartement des Gémeaux tensioactif affaiblit son interaction avec l'ADN.Un autre agent a également été étudié pour sa capacité de liaison à l'ADN et nous présentons une étude systématique sur les interactions entre tensioactif cationique liquide ionique [C12mim]Br et de l'ADN par des techniques expérimentales et de dynamique moléculaire (MD) de simulation. En ajoutant [C12mim]Br, les chaînes d'ADN sont soumis à compactage, des changements conformationnels, avec le changement de charge nette portée par le complexe ADN/tensioactif. simulation de MD confirme les résultats expérimentauxBearing a hydrophilic part and a hydrophobic part, surfactants can adsorb onto interfaces and lower the interfacial tension (γ), thereby enhancing the interfacial properties and leading to the applications in cleaning, surface functionalization, foaming and emulsification. Charged surfactants are also used in biological applications, in particular to extract and purify DNA, or for gene delivery. In this thesis we have studied the adsorption properties of surfactants, both to air/water interfaces and onto DNA to form complexes. The first part of the thesis concentrates on interfacial studies of surfactants. To understand how they work in these applications it is important to know the time-scales of the surfactant adsorption and desorption. Thus it is necessary to investigate the adsorption and desorption kinetics, which are already widely studied. However, traditional studies tend to make many assumptions, for example, extending the applicability of equilibrium relations to non-equilibrium cases. In this dissertation, the adsorption of two different surfactant systems has been investigated, non-ionic surfactant C12E6 and ionic surfactant CTAB with sufficient salt. A single bubble compression measurement combined with a known equilibrium surface tension (γeq) value allows the determination of γ(Γ), which is more accurate than results from traditional methods. The time-dependent surface concentrations are measured, showing that the adsorption is diffusion controlled at short times.Having shown that adsorption is diffusion controlled, we report desorption of surfactants from the air/water interface for different systems. The desorption processes are confirmed not to be purely diffusion-limited, showing the presence of an energy barrier. The energy barrier is influenced by the alkyl chain length, but not the counterion type.In the second part of the thesis we concentrate on DNA/surfactant systems. Although the interaction between cationic surfactant and anionic polyelectrolyte has been extensively studied, there still remains need to further understand the complex system, especially to rationalize the choice of surfactants to reach controllable DNA binding ability and low toxicity to the organism. In this dissertation, we introduced the systematic investigation on the interactions of two cationic surfactants with DNA.The first surfactant used is a cationic gemini surfactant 12-2-12∙2Br. Before using it with DNA a thorough characterization has been carried out. The equilibration of 12-2-12∙2Br onto an air/water interfaces in the absence of electrolyte is very slow. Addition of NaBr hardly affects the adsorption kinetics at short times, during which the adsorption is diffusive. However, the adsorption equilibrates much faster. The micellization of cationic gemini surfactant 12-3-12·2Br has been investigated. The critical micelle concentration (CMC) increases slightly with temperature and decreases with ionic strength. 12-3-12·2Br interacts strongly with DNA, due to the electrostatic attraction between the two and the hydrophobic interactions between alkyl chains. Salt screens the electrostatic attraction, while increasing spacer length of gemini surfactant weakens its interaction with DNA.Another surfactant has also been studied for its DNA binding ability and we present a systematic study on interactions between cationic ionic liquid surfactant [C12mim]Br and DNA by experimental techniques and Molecular Dynamics (MD) simulation. By adding [C12mim]Br, DNA chains undergo compaction, conformational changes, with the change of net charges carried by the DNA/surfactant complex. MD simulation confirms the experimental results
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Gray, Jason. "Monoglyceride food surfactants and their interaction with whey proteins". Thesis, University of Salford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301418.
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Corbyn, Conrad Paul. "Interactions of cationic and nonionic surfactants with DNA". Thesis, University of Hull, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.402989.
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Wesley, Robin David. "The interactions between polymers and surfactants at interfaces". Thesis, University of Bristol, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285889.
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Hagenhoff, Kerstin. "Investigations into soil-surfactant interactions in relation to soil washing". Thesis, University of Greenwich, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.401595.
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Augusto, Luis. "Interactions et effets des lipopolysaccharides bactériens dans l'alvéole pulmonaire". Paris 11, 2002. http://www.theses.fr/2002PA112239.
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Rodenhiser, Andrew Paul. "Fluorescence probing and size exclusion chromatographic studies of polymer-surfactant interactions". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0017/NQ49287.pdf.
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Charlton, Ian David. "New insights into micellar structural evolution and interaction using voltammetric methods". Thesis, University of Newcastle Upon Tyne, 1999. http://hdl.handle.net/10443/798.
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The development of electrochemical techniques as applied to self-assembled supramolecular systems (e. g. micelles) has advanced over the past decade. The main properties that have been elucidated by these techniques have been micellar selfdiffusion and size. Although there are reports that have paid attention to the qualitative influence of intermicellar interactions on the behaviour of the micellar system, quantitative assessments of interaction are very limited. In this thesis, the application of rotating disk voltammetry, primarily, has led to a quantitative rationalisation of intermicellar interactions in cationic and nonionic micellar systems over a range of surfactant and electrolyte concentrations. Two `normal' micellar systems are studied with aggregates formed from cationic (CTAC) and nonionic (Triton X-100) surfactants. Initial measurements and analysis yields micellar sizes that are consistent with published values, demonstrating the validity and the ease of application of electrochemical techniques. Measuring self-diffusion coefficients over a range of electrolytes provides a comprehensive assessment of micellar phase behaviour and yields further structural parameters which are conventionally determined using a variety of methods. The first reported study of electrochemistry in a reverse micelle `nanoemulsion' is presented. The growth in micellar size on the addition of a solubilised probe gives important inferences for the careful control of particle growth in a reverse micelle `nano-reactor'. In summary, the thesis, as the title states, gives new insights pertaining to micellar structural evolution and interaction. The thesis will examine the benefits of applying electrochemical techniques to study micellar systems and concentrate, predominately, on the wealth of information that can be obtained by the resultant analysis. The work forms an excellent basis for not only further quantitative analysis but also as a phenomenological template for employment in the study of a diversity of self-assembled supramolecular species.
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Amar, Khodja Ahcène. "Interactions entre molecules hydrophobes et micelles mixtes ioniques formees par des melanges binaires de surfactifs : influence des caracteristiques physico-chimiques des melanges". Paris 6, 1987. http://www.theses.fr/1987PA066235.
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Etude de la solubilisation du pentanol-1 dans des micelles mixtes d'agents de surface anioniques, cationiques, non ioniques, hydrogenes et perfluores, et de la perturbation de la condensation ionique a la surface micellaire
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Suzzoni, Ariane. "Evolution de la structure des minéraux argileux lors de leurs interactions avec des tensioactifs anioniques". Thesis, Sorbonne université, 2019. http://www.theses.fr/2019SORUS464.
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Dans le domaine pétrolier, une des méthodes utilisées afin d’augmenter le rendement des gisements est l’injection de tensioactifs. Toutefois, les interactions entre entités organiques et minéraux argileux présents au sein des réservoirs peuvent engendrer diverses complications. Une meilleure compréhension des interactions entre minéraux argileux et tensioactifs est donc primordiale afin d’anticiper les réactions pouvant se produire au sein du réservoir. Le système étudié se compose de kaolinite et illite et d’AOT et SDBS. L’analyse des isothermes d’adsorption renseigne sur les mécanismes d’interactions qui dépendent fortement du pH. Sur la base des mécanismes identifiés, nous nous sommes ensuite intéressés à l’influence de la concentration en tensioactif sur la stabilité de suspensions aqueuses d’illite et de kaolinite en combinant des expériences macroscopiques de suivi temporel de la sédimentation, des mesures rhéologiques et des expériences de diffusion des rayons X aux petits angles (SAXS). Dans le cas de la kaolinite, les mesures macroscopiques révèlent une désagrégation des particules en présence de tensioactif. L’analyse de la structure microscopique des suspensions par SAXS montre un lien fort entre la concentration et l’orientation des particules individuelles au sein des sédiments, qui dépendent fortement du pH et de la concentration en tensioactif anionique. Les comportements des suspensions d’illite sont significativement différents et on n’observe notamment que peu d’orientation des particules au sein des sédiments. L’origine de ces différences semble principalement liée aux différences de taille, de forme et de charge entre ces deux minérauxIn the oil industry, a commonly used method for increasing oil yield is to inject into the reservoir various organic chemicals. However, various interactions between such organic species and clay minerals naturally present in the reservoir rocks sometimes generate numerous detrimental effects. It is of prime importance to better assess and understand the interactions between clay minerals (kaolinite and illite) and surfactant molecules (AOT and SDBS). Adsorption in aqueous suspensions of anionic molecules onto the selected clay minerals was studied at different pH using the rest method. A thorough analysis of the obtained adsorption isotherms allows obtaining information about interaction mechanisms that are highly pH-dependent. On the basis of the thus identified mechanisms, we then focused on the influence of surfactant concentration on the stability of aqueous suspensions of kaolinite and illite. Such an analysis was carried out by combining macroscopic observations of the time evolution of sedimentation, rheological measurements and Small Angle X-ray Scattering (SAXS) experiments. In the case of kaolinite, macroscopic measurements reveal particle disaggregation in the presence of surfactant. At the microscopic level, SAXS investigations evidence strong links between volume fraction and particle orientation in the deposits, both parameters being highly dependent on pH and surfactant concentration. The behaviour of illite suspensions is significantly different as very limited orientation is observed in the sediments. Such differences in behaviour between both clay minerals could be tentatively assigned to differences in size, shape and charge
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Green, Rebecca J. "Protein/polymer interactions investigated by surface plasmon resonance". Thesis, University of Nottingham, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336926.
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Cattoz, Beatrice Nicole. "Interactions in complex solutions of polymers, particles, salts and surfactants". Thesis, University of Bristol, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.566814.
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Environmental pressures are driving detergent formulations to become ever-more so- phisticated blends of stabilisers; probing the interactions occurring in complex systems of hydrosoluble polymers with surfactants and their adsorption onto particles is key for the understanding of the mechanism of colloidal stability. In this thesis, the polymer-polymer and polymer-surfactant interactions have been investigated both in bulk and at the solid/liquid interface. The main techniques used were solvent relaxation NMR, photon correlation spectroscopy, small angle neutron scattering, diffusion NMR and optical reflectometry. The majority of experiments involved polyvinyl pyrrolidone, PVP, adsorbed on silica. Addition of sodium dodecyl sulfate, SDS, decreased the adsorbed amount but increased the layer thickness, leaving the remaining adsorbed polymer in an extended conformation caused by repulsive interactions amongst adsorbed surfactant aggregates and the silica interface. The introduction of a nonionic alcohol ethoxylate surfactant to this system prevented the desorption of the polymer layer as it formed mixed micelles with SDS reducing the total charges per micelle and lowering repulsions between the surface and the surfactant micelles. The effect of a non-adsorbing polymer, sodium polystyrene sulfonate, aPSS, on the stability of silica particles was also investigated, showing that addition of the polyelec- trolyte to the silica dispersion modifies the interparticles interactions. Small roughly spherical clusters were formed, followed by larger, less spherical aggregates resulting in the formation of a dense gel network. Exploring the PVP /N aPSS system showed that these polymers interact in bulk forming NaPSS-rich complexes; interfacial investigations revealed that adding aPSS to PVP previously adsorbed on silica led to surface complexes formation. Finally exposing PVP to sodium polyacrylate revealed some polymer interactions at high pH. These interactions were favoured by increasing molecular weights; adding this polymer to PVP adsorbed onto silica lead to a small decrease in adsorbed amount and some particle aggregation.