Dissertations / Theses on the topic 'Osmotic coefficients'
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Knutsen, Jeffrey Steven. "Membrane bioseparations: Cellulase recovery, particle deposition, and second osmotic virial coefficients." Diss., Connect to online resource, 2005. http://wwwlib.umi.com/dissertations/fullcit/3165833.
Full textParupudi, Arun Kumar. "Demonstration of scale-down dynamic light scattering and determination of osmotic second virial coefficients for proteins." Master's thesis, Mississippi State : Mississippi State University, 2007. http://sun.library.msstate.edu/ETD-db/theses/available/etd-11092007-112135/.
Full textBley, Michael. "Simulating Osmotic Equilibria by Molecular Dynamics - From Vapor-Liquid Interfaces to Thermodynamic Properties in Concentrated Solutions." Thesis, Montpellier, 2018. http://www.theses.fr/2018MONTS122.
Full textThe aim of this PhD thesis is the development of a new theoretical method based on the simulation of vapor-liquid equilibria by means of molecular dynamics (MD) simulation. This new method predicts thermodynamic properties such as solvent activities and solute activity coefficients of aqueous and organic phases used in liquid-liquid extraction systems. These thermodynamic properties are required for mesoscopic thermodynamic modeling approaches estimating the efficiency and selectivity of a given solvent extraction system up to an industrial scale. Thermodynamic and structural properties of aqueous electrolyte solutions and organic solvent phase including aggregates resulting from amphiphilic extractant molecules are reproduced in very good agreement with previously available experimental and theoretical data. The osmotic equilibrium MD approach provides a new and powerful tool for accessing thermodynamic data
Guell, David Charles. "The physical mechanism of osmosis and osmotic pressure--a hydrodynamic theory for calculating the osmotic reflection coefficient." Thesis, Massachusetts Institute of Technology, 1991. http://hdl.handle.net/1721.1/29859.
Full textBhalla, Gaurav Ph D. Massachusetts Institute of Technology. "Osmotic reflection coefficient." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/51614.
Full textIncludes bibliographical references (leaves 149-152).
The presence of a discriminating barrier separating two solutions differing in concentration generates a net volume flux called osmotic flow. The simple case is of the ideal semi-permeable membrane which completely excludes the solute. The flow through such a membrane is directly proportional to the thermodynamic pressure drop less the osmotic pressure drop. For membranes which partially exclude the solute the osmotic contribution to flow is less than that of the semi-permeable membrane, and the reduction is given by the osmotic reflection coefficient [sigma]o,. This work was motivated by understanding the mechanistic aspects of osmotic flow through such membranes, in order to predict [sigma]o. One of the main goals of the research was to develop computational models to predict [sigma]o for charged porous membranes and charged fibrous membranes. The effects of molecular shape on [sigma]o for rigid macromolecules in porous membranes were analyzed using a hydrodynamic model. In this type of model, employed first by Anderson and Malone, steric exclusion of the solute from the periphery of the pore induces a concentration-dependent drop in pressure near the pore wall, which in turn causes the osmotic flow (Anderson and Malone 1974). Results were obtained for prolate spheroids (axial ratio, [gamma] > 1) and oblate spheroids ([gamma] < 1) in cylindrical and slit pores. Two methods, one of which is novel, were used to compute the transverse pressure variation. Although conceptually different, they yielded very similar results; the merits of each are discussed. For a given value of a/R, where a is the prolate minor semiaxis or oblate major semiaxis and R is the pore radius, [sigma]o, increased monotonically with increasing [gamma]. When expressed as a function of aSEIR, where asE is the Stokes-Einstein radius, the effects of molecular shape were less pronounced, but still significant. The trends for slits were qualitatively similar to those for cylindrical pores. When [sigma]o was plotted as a function of the equilibrium partition coefficient, the results for all axial ratios fell on a single curve for a given pore shape, although the curve for cylindrical pores differed from that for slits. For spheres ([gamma]= 1) in either pore shape, [sigma]o was found to be only slightly smaller than the reflection coefficient for filtration (of). That suggests that [sigma]o can be used to estimate of for spheroids, where results are currently lacking. A computational model was developed to predict the effects of solute and pore charge on [sigma]o, of spherical macromolecules in cylindrical pores. Results were obtained for articles and pores of like charge and fixed surface charge densities, using a theory that combined low Reynolds number hydrodynamics with a continuum, point-charge description of the electrical double layers. In this formulation steric and/or electrostatic exclusion of macromolecules from the vicinity of the pore wall creates radial variations in osmotic pressure. These, in turn, lead to the axial pressure gradient that drives the osmotic flow. Due to the stronger exclusion that results from repulsive electrostatic nteractions, ao, with charge effects always exceeded that for an uncharged system with the same solute and pore size. The effects of charge stemmed almost entirely from particle positions within a pore being energetically unfavorable. It was found that the required potential energy could be computed with sufficient accuracy using the linearized Poisson-Boltzmann equation, high charge densities notwithstanding. In principle, another factor that might influence o in charged pores is the electrical body force due to the streaming potential. However, the streaming potential was shown to have little effect on [sigma]o, even when it markedly reduced the apparent hydraulic permeability. A model based on continuum hydrodynamics and electrostatics was developed to predict the combined effects of molecular charge and size on the o, of a macromolecule in a fibrous membrane, such as a biological hydrogel. The macromolecule was represented as a sphere with a constant surface charge density, and the membrane was assumed to consist of an array of parallel fibers of like charge, also with a constant surface charge density. The flow was assumed to be parallel to the fiber axes. The effects of charge were incorporated into the model by computing the electrostatic free energy for a sphere interacting with an array of fibers. It was shown that this energy could be approximated using a pairwise additivity assumption. Results for [sigma]o, were obtained for two types of negatively charged fibers, one with properties like those of glycosaminoglycan chains, and
(cont.) the other for thicker fibers having a range of charge densities. Using physiologically reasonable fiber spacings and charge densities, [sigma]o, for BSA in either type of fiber array was shown to be much larger than (often double) that for an uncharged system. Given the close correspondence between [sigma]o and the [sigma]f; the results suggest that the negative charge of structures such as the endothelial surface glycocalyx is important in minimizing albumin loss from the circulation.
by Gaurav Bhalla.
Ph.D.
Crozier, Paul S. "Slab-Geometry Molecular Dynamics Simulations: Development and Application to Calculation of Activity Coefficients, Interfacial Electrochemistry, and Ion Channel Transport." BYU ScholarsArchive, 2002. https://scholarsarchive.byu.edu/etd/2.
Full textKebe, Mouhamadou. "Incidence de traitements thermiques sur le parenchyme de Pomme (Malus Domestica) et diffusion des composés phénoliques." Thesis, Avignon, 2014. http://www.theses.fr/2014AVIG0253/document.
Full textApple (Malus domestica Borkh. ) fruit widespread in temperate countries, is much consumed.It represents an important source of phenolic compounds. This study was interestedin polyphenol content of apple tissue parenchyma. The problem concerns effects of texturedegradation on the diffusion of polyphenols molecules. The originality of the approach isbased on the combination of texture, osmotic pressure and polyphenol leaching. Physicaland biochemical methods were used to measure changes at macroscopic scale and chemicalchanges occurring in the parenchymateous tissue . The study of mass transfer highlightedvarious factors that may affect apparent coefficient diffusion. The result showed that thedisintegration of texture , thickness, apple variety and osmotic pressure of leaching mediacan influence mass transfer yield. The study of the Cell walls components showed changesthat occur during leaching process. Light microscopic analysis revealed changes at cellularscale, procyanidins the major polyphenols, leaching phenomena and also interactionswith cell walls matrix
Verma, Kusum S. "The osmotic second virial coefficient as a predictor of protein stability." Master's thesis, Mississippi State : Mississippi State University, 2006. http://sun.library.msstate.edu/ETD-db/ETD-browse/browse.
Full textMiller, Mark Stephen. "Use of osmotic coefficient measurements to validate and to correct the interaction thermodynamics of amino acids in molecular dynamics simulations." Diss., University of Iowa, 2018. https://ir.uiowa.edu/etd/6476.
Full textHersh, Lawrence T. "Mathematical techniques for the estimation of the diffusion coefficient and elimination constant of agents in subcutaneous tissue." [Tampa, Fla.] : University of South Florida, 2007. http://purl.fcla.edu/usf/dc/et/SFE0002035.
Full textGe, Xinlei. "Extraction of Metal Values : Thermodynamics of Electrolyte Solutions and Molten Salts Extraction Process." Doctoral thesis, Stockholm : Skolan för industriell teknik och management, Kungliga Tekniska högskolan, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10638.
Full textMonnerat, Sandra Mourão. "Desidratação osmotica e secagem convectiva de maçã : transferencia de massa e alterações de estrutura celular." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/256446.
Full textTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
Made available in DSpace on 2018-08-13T18:52:37Z (GMT). No. of bitstreams: 1 Monnerat_SandraMourao_D.pdf: 2359962 bytes, checksum: 3df7969a948ecae9b1a169de42e7087a (MD5) Previous issue date: 2009
Resumo: No presente trabalho investigou-se a desidratação osmótica de maçãs (variedade Fuji), seguida ou não de secagem convectiva com ar quente. Foram determinados perfis de concentração de água e soluto(s) em amostras de maçãs cortadas ao meio e desidratadas osmoticamente em soluções aquosas binárias (30% e 50% de sacarose, p/p) e solução ternária (50% de sacarose e 10% de cloreto de sódio, m/m), sob agitação vigorosa e temperatura constante (27°C). As amostras imersas na solução osmótica durante 2, 4 e 8 h foram fatiadas a partir da superfície plana exposta. A densidade e os teores de água, açúcares totais e redutores e cloreto de sódio foram determinados em cada fatia. O modelo matemático que descreve o transporte de cada espécie estudada (água, sacarose e cloreto de sódio) se baseia na equação de continuidade e na Lei de Fick e considera o encolhimento do tecido. O modelo foi ajustado aos dados experimentais, através do método implícito de diferenças finitas de Crank-Nicolson para determinar os coeficientes efetivos de difusão como uma função da concentração, utilizando coordenadas materiais e integrando simultaneamente as equações diferenciais de cada componente (água e sacarose ou água, sacarose e cloreto de sódio). Imagens de microscopia ótica de tecidos tratados osmoticamente, previamente pigmentados com o corante vital vermelho neutro, foram obtidas variando-se a concentração das soluções e o tempo de exposição. Os registros fotográficos retratam alterações da estrutura celular, que variam de acordo com a intensidade do processo de desidratação. A secagem convectiva com ar quente foi realizada em amostras de maçãs cortadas ao meio, frescas e previamente tratadas em solução aquosa de sacarose a 50% p/p durante 4 horas (27°C). Os perfis de umidade foram determinados a partir da superfície, após a exposição da face plana das metades das maçãs ao fluxo de ar quente (60°C ) durante 3, 6, 10 e 24 horas de secagem. O modelo matemático que descreve o transporte da água se baseia nas equações de continuidade e na Lei de Fick e considera o encolhimento do tecido e a concentração inicial não homogênea para o tecido previamente tratado. De maneira similar à desidratação osmótica, a difusividade de água na secagem também foi determinada em função da concentração, utilizando-se o método implícito de diferenças finitas de Crank-Nicolson e coordenadas materiais. Obtevese um bom ajuste dos modelos matemáticos aos dados experimentais de desidratação osmótica e de secagem. A ordem de magnitude dos coeficientes obtidos para a desidratação osmótica foi uma ou duas vezes menor que de coeficientes de difusão binários de soluções puras de sacarose e de cloreto de sódio. No caso da secagem, o comportamento da difusividade mostrou dependência significativa com a concentração de água. O tecido fresco apresentou coeficientes superiores aos do tecido pré-tratado osmoticamente além de funcionalidades distintas para diferentes tempos de secagem (inferior e superior a 6 horas). O tecido tratado apresentou um comportamento mais estável da difusividade da água no material e foi descrito por uma única função. Este fato está relacionado com as mudanças estruturais ocorridas durante a secagem, mais severas para o tecido fresco em relação ao tecido tratado
Abstract: In this study it was investigated the osmotic dehydration of apples (Fuji variety) followed or not by convective drying with hot air. Concentration profiles were determined for water and solute(s) in samples of apples cut in half and osmotically dehydrated in binary aqueous solutions (30% and 50% sucrose, w/w) and ternary solution (50% sucrose and 10% sodium chloride, w/w) under vigorous stirring and constant temperature (27°C). The samples immersed in the osmotic solution for 2, 4 and 8 h were sliced from the exposed flat surface. The density and water, total and reducing sugars and sodium chloride contents were determined in each slice. The mathematical model that describes the transport of each species studied (water, sucrose and sodium chloride) is based on the continuity equation and on the of Fick's diffusion law and considers the tissue shrinkage. The model was fitted to experimental data through the finite difference implicit method of Crank-Nicolson, to determine the effective diffusion coefficients as a function of concentration, using material coordinates and integrating simultaneously the differential equations of each component (water and sucrose or water, sucrose and sodium chloride). Light microscopy images of osmotically processed tissues previously pigmented with the vital dye neutral red, were obtained, varying the concentration of solutions and time of exposure. The photographic records show changes in cellular structure, which vary with the intensity of the dehydration process. The convective air drying was carried out on samples of apples cut in half, fresh and treated in aqueous solution of sucrose to 50% w/w for 4 hours (27°C). The moisture profiles were determined from the surface, after exposure of the flat face of half of the apples to the flow of hot air (60 ° C) during 3, 6, 10 and 24 hours of drying. The mathematical model that describes the water transport is based on the continuity equation, the Fick's diffusion law, the tissue shrinkage and the nonhomogeneous initial concentration of the previously treated tissue. Similarly to the osmotic dehydration, the water diffusivity in drying was also determined in terms of concentration, using the finite difference implicit method of Crank-Nicolson and coordinated materials. It was possible to obtained a good fit of mathematical models to experimental data of osmotic dehydration and drying. The order of magnitude of the coefficients obtained for the osmotic dehydration was one or two times lower than diffusion coefficients of pure binary solutions of sucrose and sodium chloride. For drying, the behavior of diffusivity showed significant dependence with the concentration of water. The fresh tissue showed coefficients greater than the osmotically pre-treated tissue than it needs distinct functions for different times of drying (and less than 6 hours). The treated tissue showed a more stable behavior of the water diffusivity in the material and was described by a single function. This fact is related to the structural changes during drying, more severe for the fresh tissue than for the treated tissue
Doutorado
Doutor em Engenharia de Alimentos
Hubert, Nathalie. "Contribution à la détermination des propriétés thermodynamiques des solutions aqueuses d'électrolytes forts : étude des systèmes H2O-NaCl et H2O-Na2SO4 entre 25°C et 100°C par mesures d'équilibre liquide-vapeur et par calorimétrie." Vandoeuvre-les-Nancy, INPL, 1996. http://www.theses.fr/1996INPL005N.
Full textBohne, Guido. "Ausgewählte Eigenschaften des Sporopollenins der Kiefer." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2007. http://dx.doi.org/10.18452/15590.
Full textSubject of this thesis are relationships between physicochemical properties and functions of the exine concerning propagation, pollination and fecundation. Here the application of the 3-chambered sporopollenin-microcapsules (central capsule and sacci) in permeation chromatography proved of value. Both the kinetically dependent dispersion of small molecules and changes in concentration of sugars and dextran molecules in the medium were analysed to determine permeability coefficients of the nexine. The water absorption capacity of exine fragments and the hydraulic conductance of the nexine were calculated by means of changes in concentrations of excluded dextran molecules. The tectum of the saccal sexine is a microfiltration membrane with a sharp cut off in the submicrometer range; thus hydrocolloids with Stokes´radii over 100 nm (e.g. from native dextran) are excluded from the sacci. The nexine is a non-ideal reverse osmosis membrane having high reflexion coefficients in sugar and salt solutions; in addition few large pores allow the exchange of sugars and even of small polymers. The hydraulic conductance of the nexine is in the range typically for plasmamembranes (0.39-0.48 µm s-1 MPa-1); the results indicate that the exine does neither obstruct the uptake of nutrients by the sporoplast from the locular fluid nor hinder the rapid rehydration in the micropyle. When rehydrating, the distal foldings of the nexine (above the sacci) and the omega-like folding of the exine between the sacci (leptom), provide protection for the plasmamembrane when its surface area has to increase too rapidly. The corpus can be loaded with a concentrated electrolyte solution. When subsequently transferred into water the exine rupture and the sporoplast along with the intact intine is ejected. Water and other polar liquids adhere stronger to sporopollenin than hydrophobic ones. The matrix of sporopollenin show a high density in its solid content, water absorption capacity is low (0.18 mL g-1 DM) and it is resistant to deformation. This enable the formation of powder while dehydrating.
Fang, Che-Ming, and 房哲名. "Osmotic pressure and virial coefficients of star polymer solutions : dissipative particle dynamics." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/28505596559777229958.
Full text國立中央大學
化學工程與材料工程研究所
96
The osmotic pressure Π and virial coefficients ( B2 and B3 ) of linear and star polymers in good solvents are studied by dissipative particle dynamics simulations. The dependence of the osmotic pressure on the concentration c is directly caculated by considering two reservoirs separated by a semi- permeable, fictitious membrane. For linear polymers with chain length N, our simulation results confirm the scaling relations that B2 ~ N3ν in the dilute regime and Π ~ c2.70 in the semi-dilute regime. The exponent is greater than 9/4 due to the nature of soft beads. For star polymers, the scaling relations become B2 ~ Rg3 in dilute regime and Π λcα in semi-dilute regime. Both the prefactor λ and exponent α vary with the arm number but is independent of the arm length. As the arm number is increased, the exponent may rise from 2.7 to 3.07, which is qualitatively consistent with the experimental result.
Prickett, Richelle Catherine. "The application of the multisolute osmotic virial equation to cryobiology." Phd thesis, 2009. http://hdl.handle.net/10048/849.
Full textTitle from pdf file main screen (viewed on Jan. 15, 2010). A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Chemical Engineering and Medical Sciences, Departments of Chemical and Materials Engineering and Medical Sciences - Laboratory Medicine and Pathology, University of Alberta. Includes bibliographical references.
Duignan, Timothy Thomas. "Modelling specific ion effects with the continuum solvent." Phd thesis, 2015. http://hdl.handle.net/1885/13642.
Full textYANG, FENG-RU, and 楊奉儒. "The reflection coefficient for macromolecules in the osmotic flow through small pores." Thesis, 1987. http://ndltd.ncl.edu.tw/handle/81065045715299935066.
Full textMazzini, Virginia. "Specific ion effects in non-aqueous solutions." Phd thesis, 2017. http://hdl.handle.net/1885/144595.
Full text