Literatura académica sobre el tema "Associative colloids"
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Artículos de revistas sobre el tema "Associative colloids"
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Shmotolokha, V. I. y M. F. Holovko. "Dimerizing hard spherocylinders in porous media". Condensed Matter Physics 27, n.º 1 (28 de marzo de 2024): 13607. http://dx.doi.org/10.5488/cmp.27.13607.
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This research focuses on the unique phase behavior of non-spherical patchy colloids in porous environments. Based on the theory of scaled particle (SPT), methods have been refined and applied to analyze the thermodynamic properties of non-spherical patchy particles in a disordered porous medium. Utilizing the associative theory of liquids in conjunction with SPT, we investigated the impact of associative interactions and connections between the functional nodes of particles on the formation of the nematic phase. Calculations of orientational and spatial distributions were conducted, which helped to understand the phase behavior of particles during the transition from isotropic to nematic phase under the spatial constraints imposed by the disordered matrix of the porous medium.
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Mitra-Delmotte, Gargi y Asoke Nath Mitra. "Softening the “Crystal Scaffold” for Life’s Emergence". Physics Research International 2012 (21 de febrero de 2012): 1–13. http://dx.doi.org/10.1155/2012/232864.
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Del Giudice’s group studies how water can organize on hydrophilic surfaces forming coherent domains (loaning energy from the quantum vacuum), plus quasifree electrons, whose excitations produce cold vortices, aligning to ambient fields. Their electric and magnetic dipolar modes can couple to oscillatory (electric-organic dipoles) and/or rotary (magnetic-mineral dipoles), besides responding to magnetic potentials. Thus, imprinted electromagnetic patterns of catalytic colloids—compared with Cairns-Smith’s “crystal scaffold”—on their structured water partners could have equipped the latter with a selection basis for “choosing” their context-based “soft-matter” (de Gennes) replacements. We consider the potential of the scenario of an external control on magnetic colloids forming in the Hadean hydrothermal setting (of Russell and coworkers)—via a magnetic rock field—conceptually enabling self-assembly, induction of asymmetries, response effects towards close-to-equilibrium dynamics, and associative networks, besides providing a coherent environment for stabilizing associated symmetry-broken quanta and their feedback interactions with those of coherent water domains, to address the emergence of metabolism and replication.
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Patel, Nirav, Ryan Guillemette, Ratnesh Lal y Farooq Azam. "Bacterial surface interactions with organic colloidal particles: Nanoscale hotspots of organic matter in the ocean". PLOS ONE 17, n.º 8 (25 de agosto de 2022): e0272329. http://dx.doi.org/10.1371/journal.pone.0272329.
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Colloidal particles constitute a substantial fraction of organic matter in the global ocean and an abundant component of the organic matter interacting with bacterial surfaces. Using E. coli ribosomes as model colloidal particles, we applied high-resolution atomic force microscopy to probe bacterial surface interactions with organic colloids to investigate particle attachment and relevant surface features. We observed the formation of ribosome films associating with marine bacteria isolates and natural seawater assemblages, and that bacteria readily utilized the added ribosomes as growth substrate. In exposure experiments ribosomes directly attached onto bacterial surfaces as 40–200 nm clusters and patches of individual particles. We found that certain bacterial cells expressed surface corrugations that range from 50–100 nm in size, and 20 nm deep. Furthermore, our AFM studies revealed surface pits in select bacteria that range between 50–300 nm in width, and 10–50 nm in depth. Our findings suggest novel adaptive strategies of pelagic marine bacteria for colloid capture and utilization as nutrients, as well as storage as nanoscale hotspots of DOM.
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Tavakkoli, Ehsan, Erica Donner, Albert Juhasz, Ravi Naidu y Enzo Lombi. "A radio-isotopic dilution technique for functional characterisation of the associations between inorganic contaminants and water-dispersible naturally occurring soil colloids". Environmental Chemistry 10, n.º 4 (2013): 341. http://dx.doi.org/10.1071/en13020.
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Environmental context The fate and behaviour of inorganic contaminants are dominated by soluble complex formation and interactions with naturally occurring colloids. Although the importance of these interactions has long been debated, our understanding of the mobility and bioavailability of contaminant–colloid associations has been hampered by the limitations of common operationally defined analytical techniques. The method developed in this study facilitates a step forward from operationally defined characterisation of the association between contaminants and colloids to a functional characterisation in terms of their exchangeability and potential bioavailability. Abstract Despite evidence that the fate and behaviour of inorganic contaminants are influenced by their interactions with water-dispersible naturally occurring soil colloids, our understanding of the mobility and bioavailability of contaminant–colloid associations has been hampered by the limitations of common operationally defined analytical techniques. In this paper, an isotopic dilution method was developed to quantify the isotopically exchangeable and non-exchangeable forms of zinc and phosphorus in filtered soil-water extracts. In addition, the effect of filter size on the determination of Zn and P exchangeability was investigated. The results showed that the isotopically non-exchangeable Zn and P in filtered soil-water extracts respectively ranged between 5 and 60% and 10 and 50% and was associated with water-dispersible colloids. Filter pore size had a significant effect on Zn and P exchangeability. Whereas the <0.1-µm filtrates contained isotopically exchangeable Zn and P fractions equal to the total Zn and P concentrations (i.e. 100% isotopically exchangeable Zn and P), the filtrates obtained from larger filter sizes (0.22, 0.45 and 0.7µm) contained increasing proportions of non-exchangeable Zn and P.
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Fernine, Yasmine, Natércia C. T. Martins, Mustapha Taleb y Tito Trindade. "Surface-Enhanced Raman Spectroscopy of Benzylpenicillin Using Silver Nanocrystals Modified with Moroccan Plant Extracts". Crystals 13, n.º 7 (16 de julio de 2023): 1105. http://dx.doi.org/10.3390/cryst13071105.
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Green chemical routes for the synthesis of colloidal metal nanocrystals have been of great interest, namely in the context of nanosciences associated with biological applications. Among these methods, the synthesis of metal colloids using medicinal plant extracts originates nanocrystals having surfaces modified with chemical compounds of biological origin, which can be further explored in association with conventional pharmaceutics. In this context, the development of spectroscopic methods that seeks for understanding the potential benefits of using formulations that contain natural compounds and metal nanoparticles with therapeutic properties is of relevance. This research describes the chemical synthesis of silver colloids via the reduction of Ag(I) in the presence of distinct aqueous plant extracts. The selected extracts were obtained from Moroccan plants that have been used in traditional therapeutic practices over the centuries. The method led to stable colloids comprising polydispersed Ag nanocrystals that show surface-enhanced Raman scattering (SERS) activity. As an illustrative scenario, these colloids have been applied to the SERS detection of the natural β-lactam antibiotic benzylpenicillin, also known as penicillin G (PG). Our results indicate that all the Ag colloids tested with the different plant extracts are SERS-active for PG without showing detrimental interference from chemical adsorbates originated from the extracts. Therefore, this spectroscopic method can be further explored for monitoring nanoformulations of pharmaceuticals and metal colloids obtained using biological synthesis.
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Heathwaite, Louise, Phil Haygarth, Rachel Matthews, Neil Preedy y Patricia Butler. "Evaluating Colloidal Phosphorus Delivery to Surface Waters from Diffuse Agricultural Sources". Journal of Environmental Quality 34, n.º 1 (enero de 2005): 287–98. http://dx.doi.org/10.2134/jeq2005.0287a.
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ABSTRACTColloid‐facilitated phosphorus (P) delivery from agricultural soils in different hydrological pathways was investigated using a series of laboratory and field experiments. A soil colloidal P test was developed that yields information on the propensity of different soils to release P attached to soil colloids. The relationship between turbidity of soil extracts and total phosphorus (TP) was significant (r2 = 0.996, p < 0.001) across a range of agricultural soils, and a strong positive relationship (r2 = 0.86, p < 0.001) was found between “colloidal P” (H2O–CaCl2 extracts) and turbidity. Linear regression of the proportion of fine clay (<2 μm) for each soil type evaluated against the (H2O–CaCl2) colloidal P fraction gave a weak but positive relationship (r2 = 0.38, p = 0.082). The relative contribution of different particle‐size fractions in transporting P in agricultural runoff from grassland soils was evaluated using a randomized plot experiment. A significant difference (p = 0.05) in both TP and reactive phosphorus (RP) in subsurface flow was recorded for different particle‐size fractions, with most TP transferred either in association with the 2‐μm fraction or with the 0.001‐μm or smaller fractions. Total P concentrations in runoff were higher from plots receiving P amendments compared with the zero‐P plots; however, these differences were only significant for the >0.45‐μm particle‐size fractions (p = 0.05), and may be evidence of surface applications of organic and inorganic fertilizers being transferred through the soil either as intact organic colloids or attached to mineral particles. Our results highlight the potential for drainage water to mobilize colloids and associated P during rainfall events.
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Kashy, Babak Kateby, Attila Podolyak, Natalya Makarova, Jarrod E. Dalton, Daniel I. Sessler y Andrea Kurz. "Effect of Hydroxyethyl Starch on Postoperative Kidney Function in Patients Having Noncardiac Surgery". Anesthesiology 121, n.º 4 (1 de octubre de 2014): 730–39. http://dx.doi.org/10.1097/aln.0000000000000375.
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Abstract Background: Whether intraoperative use of hydroxyethyl starch impairs kidney function remains unknown. The authors thus tested the primary hypothesis that Hextend promotes renal injury in surgical patients. Secondarily, the authors evaluated the dose–outcome relationship, in-hospital and 90-day mortality, and whether the relationship between colloid use and acute kidney injury (AKI) depends on baseline risk for AKI. Methods: The authors evaluated the data of 44,176 adults without preexisting kidney failure who had inpatient noncardiac surgery from 2005 to 2012. Patients given a combination of colloid and crystalloid were propensity matched on morphometric, and baseline characteristics to patients given only crystalloid. The primary analysis was a proportional odds logistic regression with AKI as an ordinal outcome based on the Acute Kidney Injury Network classification. Results: The authors matched 14,680 patients receiving colloids with 14,680 patients receiving noncolloids for a total of 29,360 patients. After controlling for potential confounding variables, the odds of developing a more serious level of AKI with Hextend was 21% (6 to 38%) greater than with crystalloid only (P = 0.001). AKI risk increased as a function of colloid volume (P < 0.001). In contrast, the relationship between colloid use and AKI did not differ on baseline AKI risk (P = 0.84). There was no association between colloid use and risk of in-hospital (P = 0.81) or 90-day (P = 0.02) mortality. Conclusion: Dose-dependent renal toxicity associated with Hextend in patients having noncardiac surgery is consistent with randomized trials in critical care patients.
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Mackay, Raymond A. "Electrochemistry in association colloids". Colloids and Surfaces A: Physicochemical and Engineering Aspects 82, n.º 1 (enero de 1994): 1–28. http://dx.doi.org/10.1016/0927-7757(93)02610-q.
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Swanton, S. W. y S. Vines. "Equilibrium leach tests: colloid generation and the association of radionuclides with colloids under simulated repository conditions". Colloids and Surfaces A: Physicochemical and Engineering Aspects 217, n.º 1-3 (abril de 2003): 71–79. http://dx.doi.org/10.1016/s0927-7757(02)00561-7.
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Raghunathan, Karthik, Anthony Bonavia, Brian H. Nathanson, Christopher A. Beadles, Andrew D. Shaw, M. Alan Brookhart, Timothy E. Miller y Peter K. Lindenauer. "Association between Initial Fluid Choice and Subsequent In-hospital Mortality during the Resuscitation of Adults with Septic Shock". Anesthesiology 123, n.º 6 (1 de diciembre de 2015): 1385–93. http://dx.doi.org/10.1097/aln.0000000000000861.
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Abstract Background Currently, guidelines recommend initial resuscitation with intravenous (IV) crystalloids during severe sepsis/septic shock. Albumin is suggested as an alternative. However, fluid mixtures are often used in practice, and it is unclear whether the specific mixture of IV fluids used impacts outcomes. The objective of this study is to test the hypothesis that the specific mixture of IV fluids used during initial resuscitation, in severe sepsis, is associated with important in-hospital outcomes. Methods Retrospective cohort study includes patients with severe sepsis who were resuscitated with at least 2 l of crystalloids and vasopressors by hospital day 2, patients who had not undergone any major surgical procedures, and patients who had a hospital length of stay (LOS) of at least 2 days. Inverse probability weighting, propensity score matching, and hierarchical regression methods were used for risk adjustment. Patients were grouped into four exposure categories: recipients of isotonic saline alone (“Sal” exclusively), saline in combination with balanced crystalloids (“Sal + Bal”), saline in combination with colloids (“Sal + Col”), or saline in combination with balanced crystalloids and colloids (“Sal + Bal + Col”). In-hospital mortality was the primary outcome, and hospital LOS and costs per day (among survivors) were secondary outcomes. Results In risk-adjusted Inverse Probability Weighting analyses including 60,734 adults admitted to 360 intensive care units across the United States between January 2006 and December 2010, in-hospital mortality was intermediate in the Sal group (20.2%), lower in the Sal + Bal group (17.7%, P < 0.001), higher in the Sal + Col group (24.2%, P < 0.001), and similar in the Sal + Bal + Col group (19.2%, P = 0.401). In pairwise propensity score–matched comparisons, the administration of balanced crystalloids by hospital day 2 was consistently associated with lower mortality, whether colloids were used (relative risk, 0.84; 95% CI, 0.76 to 0.92) or not (relative risk, 0.79; 95% CI, 0.70 to 0.89). The association between colloid use and in-hospital mortality was inconsistent, and survival was not uniformly affected, whereas LOS and costs per day were uniformly increased. Results were robust in sensitivity analyses. Conclusions During the initial resuscitation of adults with severe sepsis/septic shock, the types of IV fluids used may impact in-hospital mortality. When compared with the administration of isotonic saline exclusively during resuscitation, the coadministration of balanced crystalloids is associated with lower in-hospital mortality and no difference in LOS or costs per day. When colloids are coadministered, LOS and costs per day are increased without improved survival. A large randomized controlled trial evaluating crystalloid choice is warranted. Meanwhile, the use of balanced crystalloids seems reasonable. (Anesthesiology 2015; 123:1385-93)
Tesis sobre el tema "Associative colloids"
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Di, Dio Bruno Flavio. "Time-dependent rheology of soft particle glasses". Electronic Thesis or Diss., Université Paris sciences et lettres, 2023. http://www.theses.fr/2023UPSLS026.
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Comportement rhéologique dépendant du temps dans les verres colloïdaux de particules déformablesNous étudions des verres colloïdaux constitués de suspensions denses de particules déformables dans un fluide suspendant. Des exemples pratiques comprennent beaucoup de matériaux pâteux tels que les encres solides, les produits de soins personnels et certaines préparations alimentaires. Ces matériaux se comportent comme des fluides à seuil d’écoulement qui répondent de façon élastique à des petites déformations mais s’écoulent au-delà d’une contrainte seuil. Beaucoup de travaux expérimentaux et théoriques ont étudié leurs propriétés rhéologiques à l’état stationnaire. Les connaissances sur la réponse transitoire lors de la mise en écoulement ou au contraire lors de l’arrêt sont beaucoup moins avancées.Nous abordons ce problème dans le cas de suspensions très concentrées de microgels polyélectrolytes dont la microstructure est bien caractérisée. Sous écoulement ces verres colloïdaux accumulent des contraintes internes d’origine élastique qui relaxent très lentement de sorte qu’ils conservent au repos la mémoire de la direction dans laquelle ils ont été cisaillés. Nous proposons plusieurs protocoles de préparation qui minimisent l’effet de ces contraintes résiduelles et permettent de réaliser des expériences dénuées de biais directionnels. Les contraintes transitoires associées à la mise en écoulement sont analysées à l’aide d’expériences systématiques, de simulations, et d’un modèle phénoménologique, à la fois pour des microgels répulsifs et associatifs. Un dernier chapitre est consacré aux propriétés viscoélastiques à haute fréquence des suspensions. Nos résultats démontrent le rôle clé de la compétition entre l’élasticité due aux interactions de contact et les forces de viscosité dans le fluide suspendant. Ceci nous permet de proposer un cadre conceptuel qui rationalise les comportements dépendants du temps des verres colloïdaux de particules déformablesTime-dependent rheology of soft particle glassesSoft particle glasses are jammed suspensions of soft and deformable particles dispersed in a viscous fluid. Common examples include pasty materials such as solid inks, personal care products, and foods. They behave as yield stress fluids, which respond elastically to small perturbations, but deform irreversibly and flow when they are subjected to large enough stresses. Many experimental and theoretical studies have focused on the steady shear rheology of these materials. However much less is known about their behavior in transient situations like flow cessation or startup flow.Here we investigate the time-dependent rheology of jammed suspensions made of well-characterized polyelectrolyte microgels. Upon flow cessation, these materials store residual stresses that relax very slowly and are responsible for long-lived directional memory and aging. We design several experimental protocols that minimize residual stresses and memory making it possible to perform startup experiments without directional bias. The behavior of the stress growth function is then analyzed and discussed using systematic experiments, simulations, and a phenomenological model for microgels with both repulsive interactions and short-range associations. A final chapter is devoted to the high-frequency linear viscoelasticity of the suspensions. Overall, our results demonstrate the key role played by the competition between elastic contact forces and viscous forces, thus providing a unifying framework to rationalize the time-dependent rheology of soft particle glasses
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Costalat, Marie. "Structure et mécanisme d’élaboration de biomatériaux par complexation contrôlée de polysaccharides". Thesis, Lyon 1, 2014. http://www.theses.fr/2014LYO10265/document.
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Nos travaux ont porté sur le développement d'une méthode contrôlée de complexation de polyélectrolytes. La complexation est un processus spontané, sous contrôle cinétique et irréversible dans le cas de polysaccharides tels que le chitosane et les polysulfates, essentiellement le sulfate de dextrane ou l'héparine. Une conséquence de ce contrôle cinétique est que l'obtention d'objets de taille colloïdale requiert de travailler à fortes dilutions. De plus, les nanovecteurs obtenus ne sont pas toujours compatibles avec des conditions d'utilisation dans des milieux physiologiques. Le contrôle de l'association de polysaccharides se fait par écrantage des interactions électrostatiques attractives en présence de chlorure de sodium à la concentration au moins égale à 2 mol.L-1. L'élimination du sel par dialyse induit la formation d'hydrogels dont les caractéristiques et les propriétés dépendent principalement du rapport de charges n+/n- et de la cinétique d'élimination du sel. Ainsi, l'on peut former des hydrogels massifs ou des systèmes dispersés à des concentrations en polymères jusqu'à 30 fois plus élevées que par les méthodes sous contrôle cinétique. De plus, cette technologie permet l'encapsulation des principes actifs dans les particules qui peuvent aussi être fonctionnalisées par des biomolécules d'adressage. Le résultat majeur de ce travail réside en la maîtrise des associations entre polysaccharides de charges opposées, permettant d'obtenir des systèmes colloïdaux et massifs à fort potentiels d'applications biomédicalesOur work dealt with the development of a controlled method of polyelectrolyte complexation. The complexation is a spontaneous process, under kinetic control and irreversible in the case of polysaccharides such as the chitosan and polysulfates, essentially dextran sulfate or heparin. A consequence of this kinetic control is the requirement to work at high dilution to obtain objects of colloidal size. Moreover, the obtained nanovectors were not always adapted for use in physiological media. The control of the association of polysaccharides was achieved by screening the attractive electrostatic interactions in the presence of sodium chloride at concentration at least equal to 2 mol. L-1. Removal of salt by dialysis resulted in the formation of hydrogels, whose characteristics and properties depended mainly on the charge ratio n +/ n- and the kinetics of the salt elimination. Thus, massive or dispersed hydrogels were formed at polymer concentrations up to 30 times higher than by the methods under kinetic control. Furthermore, this technology allowed the encapsulation of active ingredients in the particles that could also be functionalized with biomolecules for targeting. The major result of this work was the control over the associations between oppositely charged polysaccharides which provided colloidal and massive systems of high potentialities in biomedical applications
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Mattiello, Maddalena. "Structure et dynamique de suspensions concentrées des colloïdes déformables molles avec liaisons associatives accordables". Electronic Thesis or Diss., Paris Sciences et Lettres (ComUE), 2018. https://pastel.hal.science/tel-03360697.
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Les colloïdes déformables sont largement utilisés comme additifs rhéologiques dans de nombreuses formulations, allant des peintures et des revêtements aux cosmétiques. Dans ce travail, nous présentons une nouvelle classe de microgels colloïdaux stimulables par le pH, dont la déformabilité et les interactions attractives inter-particulaires sont ajustables. Les microgels sont constitués d'un réseau de polyélectrolyte réticulé gonflé par l'eau, dont l'élasticité est ajustée à volonté en faisant varier la quantité de monomère réticulant pendant la synthèse. L'introduction de groupes alkyle induit des attractions de courte portée entre les microgels, dont la force dépend de la composition et de l'architecture des chaînes hydrophobes. Ce système est donc un bon candidat pour étudier les conséquences macroscopiques de la variation du potentiel d'interaction de répulsif à associatif et un modèle pour des matériaux plus complexes tels que les gels réversibles, les gels protéiques, etc. Nous avons utilisé la rhéologie non linéaire, la diffusion statique et dynamique de la lumière couplée à la vélocimétrie par images de particules (PIV) pour relier les propriétés à l'échelle des particules au comportement macroscopique des suspensions dans les régimes liquide, de verre entropique et de verre encombré.Dans une première partie, le potentiel inter-particulaire est purement répulsif mais son intensité est variée en utilisant la densité de réticulation comme paramètre de contrôle. Lors de l'augmentation de la fraction volumique des colloïdes, les suspensions de microgels fortement réticulées se comportent successivement comme des suspensions liquides, des verres entropiques et des verres encombrés. Dans ce dernier, les propriétés rhéologiques suivent les prédictions récentes pour des sphères élastiques idéales à des fractions volumiques élevées. De plus, la structure vitreuse des suspensions qui possèdent des corrélations spatiales à courte distance est responsable des couleurs structurales non iridescentes qui passent continuellement du rouge au bleu en augmentant la concentration. En revanche, les microgels faiblement réticulés présentent des propriétés mécaniques et d’écoulements décrites par des lois d’échelle nouvelles, ce qui suggère qu'ils appartiennent à une classe différente de matériaux désordonnés que nous avons appelés « colloïdes ultra-moux».La deuxième partie a été consacrée à l'étude des effets des attractions de courte portée sur les propriétés statiques et dynamiques des microgels. La comparaison avec des microgels purement répulsifs ayant exactement la même composition, la même densité de réticulation et la même taille de particule met en évidence les spécificités des microgels associatifs, qui ont un potentiel d'attraction inter-particulaire variable. Dans le régime du verre encombré, des interactions attractives sont responsables des hétérogénéités d’écoulement - une compétition entre le glissement de paroi et / ou les bandes de cisaillement - contrôlées par la force des interactions attractives. Pour rationaliser la rhéologie de ces systèmes, nous proposons un modèle à deux états impliquant deux temps caractéristiques associés à la relaxation des associations et à l'ouverture de la cage, respectivement. Ces résultats établissent un lien entre la force des attractions à courte portée et les instabilités d'écoulement macroscopiques. Enfin, nous présentons deux applications où des microgels associatifs sont utilisés dans de nouvelles formulations comme des mélanges avec des microgels non associatifs et comme stabilisants d’émulsionsSoft colloids are widely used as rheological additives in formulations as diverse as paint, coatings, and cosmetics. In this work we present a novel class of pH responsive colloidal microgels with controllable softness and tunable attractive interparticle interactions. Microgels are crosslinked polyelectrolyte networks swollen by water. The elasticity of individual microgels is tuned at will through the crosslink density which depends on the amount of multifunctional monomers introduced during the synthesis. Alkyl groups induce short range attractions between microgels, whose strength depends on the composition and the architecture of the hydrophobic chains. This system is thus a valuable candidate to elucidate the relation between the macroscopic properties and the strength of the interaction potential when it is varied from soft repulsive to soft attractive. This question is central to the behavior of materials like reversible gels or protein gels. We use non linear rheology, static and dynamic light scattering and video microscopy coupled to high speed Particle Image Velocimetry (PIV) to connect the particle scale properties to the macroscopic behavior of the suspensions in the liquid, glass and jamming regime.In a first part, the interparticle potential is purely repulsive and its strength is varied using the crosslink density as a control parameter. Upon increasing the polymer concentration, highly crosslinked suspensions successively encounter well defined glass and jamming transitions, which delimit the dilute, entropic glass, jammed glass, and dense glass regimes. In the jammed regime the rheological properties support recent predictions and simulations for ideal elastic spheres randomly packed at high volume fraction. The glass-like structure of the suspensions with short range spatial correlations is responsible for non-iridescent structural colors which shift continuously from red to blue when the concentration is increased. In contrast, weakly crosslinked microgels exhibit novel mechanical and flow properties with unprecedented scaling properties, which suggest that they belong to a different class of disordered materials that we termed ‘ultrasoft’ colloids.In the second part we investigate the effects of short range attractions on the static and dynamic properties of soft microgels. The comparison with purely repulsive microgels with exactly the same composition, crosslink density, and particle size highlights the specificities of associative microgels which have different interparticle attractive potential. In the jammed glass regime, attractive interactions are responsible for flow heterogeneities -a competition between wall slip and/or shear-banding- controlled by the strength of attractive interactions. To rationalize the rheology of associative suspensions, we propose a two-state model involving two characteristic time scales associated to the relaxation of the associations and cage opening, respectively. These results establish a link between the strength of short-range attractions and the macroscopic flow properties. Finally, we present two applications where associative microgels are used as in novel formulations as blends with the non associative and as emulsions stabilizers
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Ovchinnikov, O. V., M. S. Smirnov, A. O. Dedikova, B. I. Shapiro, T. S. Shatskikh y A. N. Latyshev. "Spectral Manifestation of Hybrid Association of Zn0.7Sd0.3S Colloidal Quantum Dots with J-Aggregates of Thiacarbocyanine Dye". Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35329.
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Spectral properties of mixtures of Zn0.7Sd0.3S colloidal quantum dots with mean diameter value of
3.5 nm with the molecules of 3,3'-di(γ-sulfopropil)-9-ethyl-4,5,4',5'-dibenzo-thiacarbocyanine betaine pyridine
salt (DEC), prepared in gelatin were investigated. The obtained data indicated that the formation of
well-luminescent trans-J-aggregates and spectral tuning in the position of the absorption band of DEC and
the luminescence band of quantum dots, providing requirements for resonant energy transfer in the hybrid
associate are the determinant factors in the increase of the luminescent emission of DEC molecules, interacting
with Zn0.7Cd0.3S colloidal quantum dots.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35329
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Chambers, Katrin Bella. "Association and Bioavailability of 17β-Estradiol with Soil and Manure Aqueous Dissolved and Colloidal Fractions". Thesis, North Dakota State University, 2014. https://hdl.handle.net/10365/27346.
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Steroidal estrogens in the environment exert toxicological effects at very low concentrations. Furthermore, dissolved and colloidal fractions of soil and manure play an important role in the environmental fate and transport of steroidal estrogens. One objective of this study was to quantify the association of the natural estrogen, 17β-estradiol (E2), with the dissolved fraction and colloidal fraction isolated from liquid swine manure (LSM), soil, and soil+LSM mixtures. The second objective of this study was to evaluate whether the E2 associated with the dissolved fraction/colloidal fraction, dissolved fraction and colloidal fraction of the various media could induce an estrogenic response. Estrogenicity was assessed using an E2 receptor (ER) competitor assay, which provided E2 equivalent concentration (EEQ) of dissolved fraction/colloidal fraction, dissolved fraction and colloidal fraction solutions created from the Soil, Soil+LSM and LSM.
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Chambers, Katrin Bella. "Association and Bioavailability of 17?-Estradiol with Soil and Manure Aqueous Dissolved and Colloidal Fractions". Thesis, North Dakota State University, 2014. https://hdl.handle.net/10365/27346.
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Steroidal estrogens in the environment exert toxicological effects at very low concentrations. Furthermore, dissolved and colloidal fractions of soil and manure play an important role in the environmental fate and transport of steroidal estrogens. One objective of this study was to quantify the association of the natural estrogen, 17?-estradiol (E2), with the dissolved fraction and colloidal fraction isolated from liquid swine manure (LSM), soil, and soil+LSM mixtures. The second objective of this study was to evaluate whether the E2 associated with the dissolved fraction/colloidal fraction, dissolved fraction and colloidal fraction of the various media could induce an estrogenic response. Estrogenicity was assessed using an E2 receptor (ER) competitor assay, which provided E2 equivalent concentration (EEQ) of dissolved fraction/colloidal fraction, dissolved fraction and colloidal fraction solutions created from the Soil, Soil+LSM and LSM.
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Audebeau, Etienne. "Fonctionnalisation et réticulation de la polyallylamine par des esters boroniques". Phd thesis, Université Pierre et Marie Curie - Paris VI, 2012. http://pastel.archives-ouvertes.fr/pastel-00733089.
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Le travail de cette thèse consiste à mettre au point des gels stimulables à partir d'un polymère hydrosoluble simple : la polyallylamine. Nous avons choisi d'utiliser la réaction réversible entre les acides boroniques et les diols pour former les points de réticulation (esters boroniques). La formation de ces esters boroniques a été étudiée pour deux systèmes modèles composés d'acide 4-carboxyphénylboronique et de cyclopentanediol ou de glucose. La fonctionnalisation de la polyallylamine est effectuée selon deux méthodes : les fonctions phénylboroniques par une réaction d'amidification via un agent de couplage carbodiimide. Les fonctions diol par une réaction d'ouverture du cycle de la gluconolactone. Cette deuxième réaction de greffage peut être réversible à pH élevé. Les mélanges de ces deux polymères permettent la formation de gels réversibles sur une large gamme de pH (pH>6). Cette efficacité de gélification, même à pH neutre, est attribuée à l'effet stabilisateur qu'exercent les fonctions amines du polymère sur les esters boroniques. Il a été également montré que les polymères greffés gluconamide peuvent facilement former des gels en présence de borax. La réaction entre une polyamine et la gluconolactone s'avère être une méthode simple et efficace pour conférer à ce type de polymère un pouvoir viscosifiant important lorsqu'il est combiné avec des dérivés portant des fonctionnalités acides boriques ou boroniques.
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Naderi, Ali. "Polyelectrolytes : Bottle-Brush Architectures and Association with Surfactants". Doctoral thesis, Stockholm : Kemi, Chemistry, Kungliga Tekniska högskolan, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4683.
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Arnould, Audrey. "Dispersions acide myristique-hydroxyde de choline : de la compréhension des mécanismes d’auto-association à l’étude des propriétés moussantes et émulsifiantes". Nantes, 2015. https://archive.bu.univ-nantes.fr/pollux/show/show?id=017ad6fd-5557-467c-b9a9-16d36cb991a1.
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Les acides gras extraits de matières premières végétales sont des tensioactifs naturels utilisés dans de nombreuses applications (savons, lubrifiants…). Cependant, leur utilisation reste limitée à cause de leur faible solubilité dans l’eau qui constitue un frein important à leur emploi. La dispersion des acides gras est donc un enjeu majeur tant d’un point de vue fondamental qu’industriel et peut être améliorée par l’ajout de contre-ion. Ainsi, l’objectif de cette thèse est de comprendre l’influence du rapport molaire entre l’acide myristique et un contre-ion organique utilisé pour sa dispersion, de la nature de celui-ci et de la température sur les propriétés d’auto-assemblage et fonctionnelles de cet acide gras. Une approche multi-échelle (diffusion des neutrons, microscopies, calorimétrie, RMN, DRX, IRTF) a été mise en oeuvre pour établir un diagramme de phase et comprendre les propriétés d’auto-assemblage en solution. Nous avons montré que le rapport molaire et la température modifiaient l’état d’ionisation de l’acide gras, l’état de la chaîne carbonée, ainsi que les interactions moléculaires modulant ainsi la morphologie des assemblages supramoléculaires. La nature du contre-ion organique influence également ces caractéristiques. Nous avons mis en évidence que les propriétés moussantes et émulsifiantes de ces systèmes sont principalement gouvernées par la morphologie de l’assemblage présent en solution et par le pH. Nous avons ensuite construit un système à base d’acide gras et d’une molécule photosensible dont les propriétés d’assemblage et moussantes peuvent être modulées par la lumièreFatty acids extracted from renewable sources are natural surfactants used in various applications (soap, lubricants…). However, their use remains limited due to their poor solubility. Improving the fatty acid dispersion is a major issue in both industrial and fundamental perspectives and can be realized by adding counterions. Consequently, the objective of this thesis is to understand the effect of the molar ratio between myristic acid and an organic counter-ion used for its dispersion, the nature of this counter-ion and the temperature of the system, on the self-assembly and functional properties. A multiscale approach (neutron scattering, microscopies, DSC, NMR, WAXS, FTIR) was carried out to establish a phase diagram and to understand the supramolecular assembly properties in solution. We showed that the molar ratio and the temperature modified the ionization state of the fatty acid, the fatty acid hydrocarbon chain state and the molecular interactions, which in turn tune the self-assembly morphology. The counter-ion chemical structure also modifies the nature of the self-assembly. We showed that the foaming and emulsifying properties are mainly governed by the self-assembly morphology and by the pH of the solution. We built a photoresponsive system based on fatty acids and a photosensitive molecule, which fatty acid self-assembly and foaming properties can be tuned by light
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Bastardo, Zambrano Luis Alejandro. "Self assembly of surfactants and polyelectrolytes in solution and at interfaces". Doctoral thesis, KTH, Ytkemi, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-425.
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This thesis focuses on the study of the interactions between polyelectrolytes and surfactants in aqueous solutions and at interfaces, as well as on the structural changes these molecules undergo due to that interaction. Small–angle neutron scattering, dynamic, and static light scattering were the main techniques used to investigate the interactions in bulk. The first type of polymer studied was a negatively charge glycoprotein (mucin); its interactions with ionic sodium alkyl sulfate surfactants and nonionic surfactants were determined. This system is of great relevance for several applications such as oral care and pharmaceutical products, since mucin is the main component of the mucus layer that protects the epithelial surfaces (e.g. oral tissues). Sodium dodecyl sulfate (SDS) on the other hand, has been used as foaming agent in tooth pastes for a very long time. In this work it is seen how SDS is very effective in dissolving the large aggregates mucin forms in solution, as well as in removing preadsorbed mucin layers from different surfaces. On the other hand, the nonionic surfactant n-dodecyl β-D-maltopyranoside (C12-mal), does not affect significantly the mucin aggregates in solution, neither does it remove mucin effectively from a negatively charge hydrophilic surface (silica). It can be suggested that nonionic surfactants (like the sugar–based C12-mal) could be used to obtain milder oral care products. The second type of systems consisted of positively charged polyelectrolytes and a negatively charged surfactant (SDS). These systems are relevant to a wide variety of applications ranging from mining and cleaning to gene delivery therapy. It was found that the interactions of these polyelectrolytes with SDS depend strongly on the polyelectrolyte structure, charge density and the solvent composition (pH, ionic strength, and so on). Large solvent isotopic effects were found in the interaction of polyethylene imine (PEI) and SDS, as well as on the interactions of this anionic surfactant and the sugar–based n-decyl β-D-glucopyranoside (C10G1). These surfactants mixtures formed similar structures in solutions to the ones formed by some of the polyelectrolytes studied, i.e. ellipsoidal micelles at low electrolyte concentration and stiff rods, at high electrolyte and SDS concentrations.QC 20100901
Libros sobre el tema "Associative colloids"
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Polymer Physics: Applications to Molecular Association and Thermoreversible Gelation. Cambridge: Cambridge University Press, 2011.
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1937-, Glass J. E. y American Chemical Society. Division of Polymeric Materials: Science and Engineering., eds. Polymers in aqueous media: Performance through association. Washington, DC: American Chemical Society, 1989.
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European Conference on Coal Liquid Mixtures (2nd 1985 London, England). Second European Conference on Coal Liquid Mixtures: A three day symposium organised by the Institution of Chemical Engineers in association with the Institute of Energy and held in London, 16-18 September 1985. Oxford, OX, England: Pergamon Press, 1985.
Buscar texto completoCapítulos de libros sobre el tema "Associative colloids"
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Tadros, Tharwat F. y Steven Housley. "Use of Associative Thickeners as Rheology Modifiers for Surfactant Systems". En Colloids in Cosmetics and Personal Care, 79–91. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2011. http://dx.doi.org/10.1002/9783527631131.ch5.
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Salhotra, Ripenmeet, Adrian Wong y Manu L. N. G. Malbrain. "The Place for Starches and Other Colloids". En Rational Use of Intravenous Fluids in Critically Ill Patients, 243–57. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-42205-8_11.
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AbstractThis chapter provides a comprehensive review of synthetic colloids, specifically hydroxyethyl starch (HES) solutions, and their role in resuscitation of critically ill, perioperative, and trauma patients. This chapter addresses various questions, including the crystalloid versus colloid debate, the strengths and weaknesses of different fluid trials and meta-analyses, and the specific situations or patient groups where colloids may have an advantage. This chapter focuses on the results of five major trials that compare the use of crystalloids versus colloids in critically ill patients. The 6S study and the CHEST trial confirmed the suspicion of renal damage associated with HES solutions, and the European Medicines Agency’s (EMA) safety committee prohibited the use of HES solutions in critically ill, septic, and burn patients, or those with kidney injury in 2013. However, many questions and controversies remained thereafter and more recently the European Commission has suspended the marketing authorizations of HES solutions for infusion. The use of HES and other synthetic colloids should be restricted to resuscitation in the perioperative setting or in limited volumes with extreme caution in trauma settings outside of the EU. The take-home messages include the availability of natural and synthetic colloids, the lack of outcome benefit in clinical trials, the association of HES with renal failure and increased use of renal replacement therapy, and the unsafe use of synthetic colloids in perioperative patients. This chapter recommends limiting the dose of synthetic colloids to 30ml/kg when given in the peri- and postoperative phase.
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González García, Álvaro. "On the Colloidal Stability of Association Colloids". En Polymer-Mediated Phase Stability of Colloids, 113–29. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-33683-7_7.
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Tadros, Tharwat F. y Steven Housley. "Use of Associative Thickeners as Rheology Modifiers for Surfactant Systems". En Colloid Stability, 79–91. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2014. http://dx.doi.org/10.1002/9783527631193.ch44.
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Ward, Anthony J. I. y Charles du Reau. "Surfactant Association in Nonaqueous Media". En Surface and Colloid Science, 153–96. Boston, MA: Springer US, 1993. http://dx.doi.org/10.1007/978-1-4615-3002-2_4.
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Claesson, Per M., Andra Dedinaite, Róbert Mészáros y Imre Varga. "Association between Polyelectrolytes and Oppositely Charged Surfactants in Bulk and at Solid/Liquid Interfaces". En Colloid Stability, 337–95. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2014. http://dx.doi.org/10.1002/9783527631193.ch37.
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Lyklema, J. "Step-Weighted Random Walk Statistics, as Applied to Association Colloids". En The Structure, Dynamics and Equilibrium Properties of Colloidal Systems, 173–79. Dordrecht: Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-011-3746-1_12.
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Takahashi, M., S. Hamaguchi, H. Ito, T. Imae y T. Nakamura. "Association of block copolymers with dendritic and perfluorinated side chains in solution and at an interface". En Surface and Colloid Science, 68–73. Berlin, Heidelberg: Springer Berlin Heidelberg, 2004. http://dx.doi.org/10.1007/b97084.
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Dwiecki, Krzysztof y Ewa Bąkowska. "The Effects of Association Colloids on Lipid Autoxidation in Bulk Oils". En Lipid Oxidation in Food and Biological Systems, 257–75. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-87222-9_12.
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Claesson, Per M., Andra Dedinaite, Róbert Mészáros y Imre Varga. "Association between Polyelectrolytes and Oppositely Charged Surfactants in Bulk and at Solid/Liquid Interfaces". En Colloid Stability and Application in Pharmacy, 337–95. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2011. http://dx.doi.org/10.1002/9783527631117.ch11.
Texto completoActas de conferencias sobre el tema "Associative colloids"
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Villeneuve, Pierre, Claire Bourlieu-Lacanal, David McClements, Eric Decker y Erwann Durand. "Lipid oxidation in emulsions and bulk oils: A review of the importance of micelles". En 2022 AOCS Annual Meeting & Expo. American Oil Chemists' Society (AOCS), 2022. http://dx.doi.org/10.21748/lzak8107.
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Lipid oxidation is a major cause of quality deterioration in food or cosmetic products. In these matrices, lipids are often present in a bulk or in emulsified forms. In both systems, the rate, extent and pathway of oxidation are highly dependent on the presence of colloidal structures and interfaces because these are the locations where oxidation normally occurs. In bulk oils, reverse micelles (association colloids) are present and are believed to play a crucial role on lipid oxidation. Conversely, in emulsions, surfactant micelles are present that also play a major role in lipid oxidation pathways. This review discusses the current understanding of the influence of micellar structures on lipid oxidation. In particular, is discussed the major impact of the presence of micelles in emulsions, or reverse micelles (association colloids) in bulk oil on the oxidative stability of both systems. Indeed, both micelles in emulsions and associate colloids in bulk oil are discussed as nanoscale structures that can serve as reservoirs of antioxidants and pro-oxidants and are involved in their transport within the concerned system. Their role as nanoreactors where lipid oxidation reactions occur is also commented. Significance of your research to the AOCS membership? The results underline the importance of a better understanding of the role of micelles in the control of lipid oxidation in food or cosmetic products.
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Cadix, Arnaud, Steven Meeker, Swati Kaushik, Elodie Haumesser y Guillaume Ovarlez. "Associative Microgels, New Self Adaptive Systems to Control Fluid Loss in Well Cementing". En Abu Dhabi International Petroleum Exhibition & Conference. SPE, 2021. http://dx.doi.org/10.2118/207472-ms.
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Abstract Fluid loss control additives are critical constituents in a cement slurry formulation to ensure even cement placement and ultimately satisfactory zonal isolation. Many technological options have been developed over the past decades to design fluid loss control additives for cementing. The most popular technologies as of today are either based on water soluble polymers or colloidal particles like latexes. As an alternative approach, in this paper we introduce a new technology based on associative or "sticky" microgels. These microgels are able to associate with one another at elevated concentration but, more surprisingly, are also able to associate under shear in the dilute regime during a filtration process. As a consequence these additives demonstrate outstanding performance as fluid loss control agents. This study focuses first on standard API filtration tests using sticky microgels, and on how their behavior in application differs from traditional systems, in particular water-based soluble polymers such as cellulosic derivatives or synthetic polymers. Our investigations then focus on the working mechanism of the microgel system by analyzing adsorption on the cement surface, rheology, and filter cake structure using Mercury Intrusion Porosimetry (MIP). Finally the behavior of sticky microgels in model filtration tests is explored with either filtration against porous ceramic discs or using microfluidic chips allowing a direct visualization of microgels during filtration. This study demonstrates that associative microgels are not controlling fluid loss through a simple size match between particles and pores within the filter cake but rather through shear-induced aggregation. Microfluidic observations reveal that aggregation occurs irreversibly as microgels are forced through the pores as the filtration process occurs. The shear-induced associated gels are particularly effective at reducing dramatically the filter cake permeability and allowing gas migration control. Interestingly the shear-induced aggregation of associative μgels seems to confer self-adaptive properties of the fluid loss additives with respect to the pore network to be clogged. Indeed, formation of shear aggregated gels larger than the individual microgels can be used to limit fluid loss even if the pore sizes are much larger than the individual microgels.
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"Development and Improvement of Organic Salt Solutions of Potassium Citrate As An Environmentally Friendly Completion Fluids for Oil and Gas Wells". En Indonesian Petroleum Association 44th Annual Convention and Exhibition. Indonesian Petroleum Association, 2021. http://dx.doi.org/10.29118/ipa21-e-279.
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This article provides information on the utilization and development of colloidal formulations based on organic potassium citrate, an alternative, environmentally friendly composite fluid that can support the drilling and production of oil and gas wells. The activity started with a laboratory-scale literature study, the formulation and modification of organic potassium citrate, testing the characteristics and performance of liquids, and improving advanced formulations. This completion fluid based on organic potassium citrate has high solubility and good stability to other pollutant particles. The colloidal organic salt system based on potassium citrate is an alternative function of the replenishment fluid (pressure holding fluid) for cleaning/deepening oil and gas wells. Currently, widely used composite fluids are chloride (Cl-), bromide (Br-), nitrate (NO3-), phosphate (PO4-), and cesium formate. However, these salt solutions are highly corrosive and are not environmentally friendly. The swelling test and the corrosion rate test are carried out using different fluids (i.e., KCl slurry, NaCl polymer, and colloidal organic citrate). The test results show that when the test is performed at room temperature for 16 hours, the organic citrate fluid's swelling rate is lower than 10%, and the KCl and NaCl sludge is higher than 20%. The result of a seven days corrosion test at 350oF is that the citric acid organic liquid is lower than 10 mpy, while KCl and NaCl are higher than 50 mpy. This completion fluid formulation based on organic citrate salts is a new type of completion fluid that has the following specifications: density up to (1.80), corrosion rate (3.19 mpy) @ 248-350oF, pH (6-8), resistance to extreme temperature, turbidity (7 NTU), a swelling rate below 10%, and has good compatibility with formation water. Also, potassium citrate organic salts can be degraded efficiently, making them safe for the environment.
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Tekiner, İsmail Hakkı, Anke Knoblauch, Bahar Özatila y Murat Ay. "Soft matter physics can set biological clock of industrial food science and (bio)technology". En 4th International Conference. Business Meets Technology. València: Editorial Universitat Politècnica de València, 2022. http://dx.doi.org/10.4995/bmt2022.2022.15542.
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Tom McLeash (2005), Professor of Natural Philosophy, says that “in science nothing stays the same. This is true not only at the level of discoveries, experiments, and theories, but also for the coherent structures and disciplines of the scientific community itself. A fascinating recent example has been the emergence of the field of ‘soft matter’ from a recognition that problems in polymer science, colloid science, liquid crystals, surfactant systems, foams, and even biological materials must draw on the same experimental and theoretical tools to make progress.” In this paper, we aim to highlight the concept of soft (condensed) matter physics and its association with industrial food science and (bio)technology within the scope of a new term “food physics”.
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Suciu, Claudiu Valentin. "Experimental Investigations on the Nano-Damping Durability". En 2008 Second International Conference on Integration and Commercialization of Micro and Nanosystems. ASMEDC, 2008. http://dx.doi.org/10.1115/micronano2008-70018.
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Connected to the nano-technological development, solid-liquid interfaces have been used to dissipate surface energies, in systems where the solid is liquid-repellent. Such interfaces are able to store, release or transform the mechanical energy. For instance, some modified silicas and zeolites in association with water have been used to build efficient ecological dampers and springs. Regarding this attractive kind of storage and loss of energy, some practical aspects, such as the endurance limits need to be clarified, and measures to augment the nano-damping durability to values required by usual machine elements (106−107 working cycles) await validation. Thus, in this work endurance tests are performed on nano-porous silica gel micro-particles by using a compression-decompression chamber. When the colloidal mixture of water and silica gel was supplied directly into the test chamber, the nano-damping performances abruptly reduced at augmentation of the number of working cycles due to the colloid leakage at the seals. Such severe leakage occurred since the clearance between the piston and cylinder (hundreds of microns), prescribed by the seals makers, was one order of magnitude larger than the diameter of silica gel particles (tens of microns); accordingly, a few layers of silica gel penetrated the gap, producing damage by abrasive wear of the seals and even of the piston surface during about 105 working cycles. In order to augment the nano-damping durability, colloidal mixture of water and silica gel is introduced inside of a tank that is separated by micro-filters from the main cylinder, in which only water is supplied. One discusses the influence of filtration on the nano-damping performances and the variation of durability versus the ratio of the filter pore’s diameter to the mean size of the silica gel particles. During a few working cycles the silica gel grains are not damaged, since the uniform pressure distribution in the liquid surrounding the particles prevent them from premature fracture, even at high-pressurization. However, silica gel grains that undergo gradually fatigue fracture are able to pass the filter and then, to escape at the test chamber seals; this produces a continuous reduction of the silica gel quantity inside of the pressurization chamber and accordingly, a proportional reduction of dissipation. On a logarithmic scale, a slight linear decreasing of the damping occurs until a critical number of working cycles; this is followed by an abrupt linear reduction of dissipation, with a slope that decreases when the diameter of the filter orifices is diminished. Despite the undesired decreasing of the nano-damping performances at augmentation of the number of working cycles, using appropriate filters the durability can be extended to reach the required life of an actual machine element.
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Almohsin, Ayman, Saad AlMutairi, Bader Alharbi y Anaam Al-ShaikhAli. "Re-Associated Polymer Particle Gels by In-Situ Nanosilica Gels for Water Shutoff Applications in Fractured Reservoirs". En SPE Conference at Oman Petroleum & Energy Show. SPE, 2024. http://dx.doi.org/10.2118/218501-ms.
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Abstract Re-association of preformed particle gel via colloidal nanosilica is an innovative kind of preformed particle gel of which particles can bond together to form a reinforced bulk gel system after being placed in a fractured having unwanted water production. The objective is to minimize water production of the oil wells by treating the non-productive conductive paths, mainly referred to as reservoir heterogeneity having natural or induced fracture which is connected to water aquifer. The ultimate objective of this research is to evaluate the newly developed systems for water shutoff application in fractured reservoir, using different testing methodologies. Thermogravimetric Analysis (TGA) and dynamic mechanical analysis were conducted to benchmark performed particle gels swelled in water and nanosilica/activator. In addition, curing time (re-association) must be defined to allow safe pumping operation of the fluid through the tubular and into the target zone; therefore, the re-association (gelation time) of the particle gels were investigated. A coreflooding test was carried-out to evaluate the plugging efficiency of the newly developed technology using an induced fractured core plugs. TGA thermograms of polymer particle gels swellen in water and Nanosilica revealed that the semi-quantitative result indicated that the total weight losses (TWL) of the samples are approximately 47wt.% and 18 wt.%, respectively, while the residual masses are found to be approximately 53 wt.% and 82 wt.%, respectively. Furthermore, the results obtained from dynamic mechanical analysis, the storage modulus (G') was much higher with particle gels swelled in in-situ nanosilica than swelled in water, the newly developed composite gels behave more solid-like material. Additionally, the (re-association of the particle gels) curing time can be controlled by adjusting activator concentration from minutes to hours, which allows a predictable and controllable pumping time. The core flooding findings unveiled that this robust newly developed material efficiently plugged the facture core with high pressure of 2000 psi. Evolving technologies are required in the oil industry to overcome the existent challenges. Re-association of preformed particle gel via In-situ nanosilica is a novel method to procedure a robust bulk gel system for water control from fractured reservoirs.
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Zancan, Maira, Andrea Pires Souto Damin, Jorge Villanova Biazus y Gabriela Dinnebier Tomazzoni. "POST-NEOADJUVANT CHEMOTHERAPY RECURRENCE IN PATIENTS WITH NODE-POSITIVE BREAST CANCER: INFLUENCE OF DIFFERENT AXILLARY APPROACHES". En XXIV Congresso Brasileiro de Mastologia. Mastology, 2022. http://dx.doi.org/10.29289/259453942022v32s1065.
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Introduction: Breast cancer treatment has drastically changed in recent decades due to a better understanding of the biology of this disease as well as an increase in diagnostic and therapeutic approaches. Axillary dissection (AD) persists as the standard treatment for axillary nodes after neoadjuvant chemotherapy (NAC); however, sentinel lymph node biopsy (SLNB) has become a promising alternative since it could spare the patient from lymphadenectomy-associated morbidity in axillary tumor regression following NAC. Objective: This study aimed to compare the recurrence rates between AD and SLNB in initially node-positive patients treated with NAC. Methods: A retrospective review was conducted for medical records of node-positive breast cancer patients treated with NAC at our institution between 2010 and 2016. Clinicopathological and surgical variables including the types of axillary approach were collected. The SLNB was performed in those who converted to node negative after NAC using technetium colloid, blue dye, or both. AD was performed in positive SLNB, missing SLNB, or persistent clinically node-positive. The association of these variables with axillary or systemic recurrences was investigated using the χ2 test. Results: The study included 131 patients, being most patients (71%) diagnosed with stage III disease. NAC produced a pathologic complete response in 22.1% of the patients. Axillary recurrence was observed in 4 (3.1%) patients (including 1 patient who underwent SLNB and 3 who underwent AD), while systemic recurrence was occurred in 37 (28.2%) patients. Regarding the axillary approach, 26% of the patients underwent SLNB, 58% AD, and 21% both techniques. A technetium-radiolabeled colloid and blue dye were both used as SLNB markers in 77.9% of the patients. The sentinel lymph node identification rate was 91.5% and the mean number of lymph nodes removed was 3 in SLNB. None of the investigated factors were significantly associated with axillary recurrence. Patients who underwent AD had higher systemic recurrence rates than those who only underwent SLNB. Conclusion: SLNB is a promising intervention for node-positive patients who convert to clinically node-negative status following NAC, since their recurrence rate was not higher than that on patients who underwent AD.
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Selling, Gordon, Milagros Hojilla-Evangelista y William Hay. "New high performance starch based emulsifiers using amylose inclusion complexes". En 2022 AOCS Annual Meeting & Expo. American Oil Chemists' Society (AOCS), 2022. http://dx.doi.org/10.21748/jnph6691.
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High value amylose inclusion complexes can be formed when corn starch (having 70% amylose) is gelatinized in the presence of hydrophobic ligands. As the components cool, the amylose wraps around the ligand to form an amylose inclusion complex (AIC). The properties of the AIC will be dependent on the selection of the ligand and the amount of amylose. AIC formed from fatty sodium/amine salts were found to be effective non-foaming emulsifiers. These AIC fatty acid/amine salts were produced using either steam jet cooking or microwave techniques. Various fatty acid/amine salts (C10-22) were produced and evaluated. Colloidal suspensions were produced using the AIC at concentrations of 0.1-3% solids, and their surface and rheological properties were then characterized. The AICs successfully formed stable emulsions with corn and other oils. The emulsification properties of the AIC is dependent on pH. Superior emulsifying activity at neutral and alkaline pH were obtained for fatty acid salt AICs when compared with commercial octenyl succinic anhydride (OSA) starch. The fatty amine salt AICs were superior at neutral and acidic pH with compared to OSA starch. Emulsions formed with the AIC were stable during long-term storage as the oil droplets were resistant to coalescence. Emulsion stability increased with ligand chain length due to viscosity differences (higher molecular weight ligand AICs have greater viscosity). The AIC are effective emulsifiers produced from readily available inexpensive ingredients (some food grade) formed via association rather than chemical bonds using current inexpensive industrial techniques.
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Jeanneaus, Ch y Y. Sultan. "ULTRASTRUCTURAL LOCALIZATION AND CHARACTERISATION OF VON WILLEBRAND FACTOR (VWF) AND TISSUE PLASMINOGEN ACTIVATOR (t-PA) IN ENDOTHELIAL CELLS (EC) AND MEGAKARYOCYTES (MK)". En XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1642911.
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The reciproqual localization of VWF and t-PA in EC and MK was analysed in EM using immunocytochemical techniques. In parallel, PAGE electrophoresis, zymographic analysis and immuno-blotting were also performed in cell extracts using specific polyclonal and monoclonal antibodies against VWF and t-PA. By immunofluorescence, VWF showed a dense granular pattern in EC, MK and platelets, although no fluorescence was observed with specific antibodies to t-PA. In contrast, at optical level, with peroxidase or alcaline phosphatase conjugated antibodies, t-PA antigen in EC, MK and platelets appear lightly distributed in the cytoplasm. More precise localization of both antigens was studies in EM after incubation of ultrathin sections with specific colloidal gold coupled antibodies. VWF was detected by specific antibodies in storage granules : γ -granules in MK and Weibel-Palade bodies in EC only reacted with specific antibodies when the storage granules were opened by thin section ; VWF antigen was associated with the tubular structures of these granules. In EC gold or peroxidase coupled antibodies showed the presence of t-PA antigen in rough ergastoplasmic reticulum (RER) saccules and total absence of this antigen in granule structures. After thrombin stimulation, stained vesicles revealed t-PA in the cytoplasm, vesicles which rapidly disappeared after being released. In cultured MK, t-PA was detected by immunoperoxidase in perinuclear cisternae and in small vesicles near the Golgi complex, suggesting the synthesis of t-PA by MK. Concommitantly to appearance of the t-PA, fibrinolytic activity was detected. Immediatly after platelet production fibrinolytic activity disappeared probably by association with an inhibitor. MK and EC extracts after electrophoresis, immunoblotting and zymographic analysis revealed the presence of biologically active t-PA at the same position. Thus the cells have a basal level of active t-PA which can also be seen in intact cells when deposited on fibrin films. However the fibrinolytic activity of t-PA is inhibited in absence of VWF as it is the case in EC of patients with severe forms of VW disease although t-PA antigen is normally present.
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Li, Lei, Xiaogang Gao, Yuliang Su, Mingjian Wang, Wendong Wang, Jiawei Tu y Xinhao Wang. "Asphaltene Precipitation Characteristics and Reservoir Damage When Applying CO2 Injection in Deep Reservoirs". En SPE Annual Technical Conference and Exhibition. SPE, 2023. http://dx.doi.org/10.2118/214805-ms.
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Abstract Asphaltenes are heavy aromatic hydrocarbon compounds contained in reservoir fluids and may precipitate when reservoir pressure is reduced by production or when gas is injected into the reservoir, and then further deposit on pore-throat surfaces causing reservoir damage. At present, the research on asphaltene precipitation and reservoir damage is carried out in conventional reservoirs, and the influence of CO2 injection under high-temperature high-pressure conditions has not yet been clearly understood. In this work, the perturbed-chain statistical associating fluid theory (PC-SAFT) is applied to construct the asphaltene precipitation envelope of crude oil under the conditions of depletion development and CO2 injection development, and the precipitation conditions of asphaltenes during CO2 injection are studied. Based on the Nghiem solid phase model, the phase state simulation of asphaltene precipitation was carried out, the characteristics of asphaltene precipitation were quantitatively described. Further, through the asphaltene deposition core experiment during the CO2 injection process, the damage degree of the reservoir after asphaltene deposition and reservoir permeability levels was evaluated. Finally, the numerical simulation study was conducted after correcting the parameters to the experimental results. The asphaltene deposition distribution in the reservoir and its influence on the productivity were evaluated. The results show that with the increase in the proportion of CO2 injection, the precipitation envelope of asphaltene expands, resulting in the earlier precipitation. While there is a crossover temperature near 140 ℃, when the temperature is lower than the crossover temperature, CO2 acts as an inhibitor. The precipitation of asphaltenes in the process of CO2 injection is the desorption of colloid-asphaltene inclusions caused by gas molecules, and then to the mutual polymerization process between dispersed asphaltene molecules. CO2 injection will increase the amount of precipitation and move the precipitation curve to the right side. The degree of permeability reduction caused by the deposition of asphaltenes in the core is 12.87% - 37.54%; the deposition of asphaltenes in the reservoir is mainly around the injection-production well and along the injected gas profile. Considering asphaltenes, the oil recovery degree is reduced by 1.5%, and the injection rate is reduced by 17%. The reservoir pressure, temperature and reservoir physical properties have a strong correlation with the degree of reservoir damage, while the initial asphaltene content has a low correlation. The main contribution of this work lies in the combination of PC-SAFT calculation, experinments, phase state simulation, and numerical simulation to predict the asphatene precipitation with different pressure, temperature, and the amount of injected gas, and clarify the influence on reservoir permeability and oil production when using CO2 injection. This work will be of great interest to operators seeking to enhance oil recovery by CO2 injection in deep reservoirs.
Informes sobre el tema "Associative colloids"
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Abdel-Fattah, Amr I. Chancellor Water Colloids: Characterization and Radionuclide Association. Office of Scientific and Technical Information (OSTI), junio de 2012. http://dx.doi.org/10.2172/1044090.
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Gschwend, P. Groundwater contaminant transport in association with colloidal microparticles and organic macromolecules; Final report. Office of Scientific and Technical Information (OSTI), diciembre de 1989. http://dx.doi.org/10.2172/137619.
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Shomer, Ilan, Louise Wicker, Uzi Merin y William L. Kerr. Interactions of Cloud Proteins, Pectins and Pectinesterases in Flocculation of Citrus Cloud. United States Department of Agriculture, febrero de 2002. http://dx.doi.org/10.32747/2002.7580669.bard.
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The overall objective was to understand the cloud flocculation of citrus juice by characterization of the interactions between proteins and pectins, and to determine the role of PE isozymes in catalyzing this phenomenon. Specific objectives were to: 1. identify/characterize cloud-proteins in relation to their coagulable properties and affinity to pectins; 2. to determine structural changes of PME and other proteins induced by cation/pectin interactions; 3. localize cloud proteins, PME and bound protein/pectates in unheated and pasteurized juices; 4. to create "sensitized" pectins and determine their effect on clarification. The original objectives were not changed but the methods and approach were modified due to specific research requirements. Two i postulates were: 1. there is a specific interaction of cloud proteins with de-esterified regions of ! pectin and this contributes to cloud loss; 2. isozymes of pectin-methyl-esterase (PME) vary in efficiency to create sensitized pectins. The appearance of citrus fruit juice is an important quality factor and is determined by the color and turbidity that .are conferred by the suspended particles, i.e., by the cloud and its homogeneity. Under some circumstances the cloud tend to flocculate and the juice clarifies. The accepted approach to explain the clarification is based on pectin demethoxylation by PME that promotes formation of Ca-pectate. Therefore, the juice includes immediate heat-inactivation upon ~ squeezing. Protein coagulation also promotes cloud instability of citrus fruit extracts. However, the clarification mechanism is not fully understood. Information accumulated from several laboratories indicates that clarification is a more complex process than can be explained by a single mechanism. The increasing trend to consume natural-fresh juice emphasizing the importance of the knowledge to assure homogeneity of fresh juice. The research included complementary directions: Conditions that induce cloud-instability of natural- juice [IL]. Evaluate purification schemes of protein [USA]. Identifications of proteins, pectin and neutral sugars ([IL]; Structure of the cloud components using light and electron microscopy and immuno-labeling of PME, high-methoxyl-pectin (HMP) and low-methoxyl-pectin (LMP); Molecular weight of calcium sensitized pectins [US]; Evaluation of the products of PME activity [US]. Fractions and size distribution and cloud components [IL-US]. The optimal pH activity of PME is 7 and the flocculation pH of the cloud is 3-4. Thus, the c roles of PME, proteins and pectins in the cloud instability, were studied in pH ranges of 2- 7. The experiments led to establish firstly repeatable simulate conditions for cloud instability [IL]. Thermostable PME (TS-PE) known to induce cloud instability, but also thermolabile forms of PME (TL-PE) caused clarification, most likely due to the formation and dissolution of inactive :. PE-pectin complexes and displacement of a protective colloid from the cloud surface [US]. Furthermore, elimination of non-PME protein increases TS-PE activity, indicating that non-PME proteins moderate PME activity [US]. Other experiments Concomitantly with the study of the PME activity but promotes the association of cloud-proteins to pectin. Adjusting of the juice pH to f 7 retains the cloud stability and re-adjusting of the pH to 40% DE reacts to immuno-labeling in the cloud fragments, whereas