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Dissertations / Theses on the topic 'Chemical Thermodynamics'
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Haghtalab, Ali. "Thermodynamics of aqueous electrolyte solutions." Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=74540.
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The focus of this work is the thermodynamics of aqueous solutions of strong electrolytes for both binary and multicomponent systems.A new excess Gibbs energy function to represent the deviations from ideality of binary electrolyte solutions was derived. The function consists of two contributions, one due to long-range forces, represented by the Debye-Huckel theory, and the other due to short-range forces represented by the local composition concept. The model is valid for the whole range of electrolyte concentrations, from dilute solutions up to saturation. The model consistently produces better results particularly at the higher concentration regions in which the other models deteriorate.
An electrochemical cell apparatus using Ion-Selective Electrodes (ISE) was constructed to measure the electromotive force (emf) of ions in the aqueous electrolyte mixtures. For the NaCl-NaNO$ sb3$-H$ sb2$O system, the data for the mean ionic activity coefficient of NaCl was obtained in order to show the reproducibility of literature data and to test the validity of the experimental procedure. The data for mean ionic activity coefficient of the following systems were also collected: (1) NaBr-NaNO$ sb3$-H$ sb2$O (a system with common ion); (2) NaBr-Ca(NO$ sb3$)$ sb2$-H$ sb2$O (a system with no-common-ion).
A novel mixing rule was proposed for the mean activity coefficients of electrolytes in mixtures in terms of the mean ionic activity coefficients of electrolytes in the binary solutions. The rule is applicable to multicomponent systems which obey Harned's Rule. Predictions are in excellent agreement with experimental data for ternary systems which follow the Bronsted specific ionic theory.
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Avlonitis, Dimitrios Anastassios. "Thermodynamics of gas hydrate equilibria." Thesis, Heriot-Watt University, 1992. http://hdl.handle.net/10399/803.
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Reservoir fluids are usually saturated with water at reservoir conditions and may form gas hydrates in transfer lines, which potentially may plug the system. For long subsea pipelines, methanol injection is the practical means for preventing hydrate formation and for decomposing blockages. For efficient and economical pipeline design and operation, phase boundaries, phase fractions and distribution of water and methanol among the equilibrium phases of the system must be accurately known. The system comprising reservoir fluids, water and methanol demonstrates a complex multiphase behaviour and currently no quantitatively adequate description for it has been detailed in the open literature. The problem is addressed in this thesis by a consistent application of classical equilibrium thermodynamics. At ordinary operating conditions any combination of as many as six phases can be potentially present. For the description of the vapour and all liquid phases, we use one cubic equation of state with nonconventional mixing rules developed as part of this work. Classical thermodynamics together with the cell theory of van der Waals and Platteeuw were employed for the development of a general model for the calculation of heat capacities of gas hydrates. A consistent methodology has also been developed for obtaining the potential parameters of the cell model. Thereafter, application of the model demonstrates that for nearly spherical guest molecules the classical cell theory is a strictly valid description of gas hydrates. However, complex guest molecules distort the hydrate lattice, resulting in variation of the numerical values of certain parameters of the model. This work presents an efficient algorithm for the solution of the problem of the identity of the equilibrium phases in multiphase systems where gas hydrates are potentially present. The algorithm is based on the alternative use of two equivalent forms of the Gibbs tangent plane criterion and it is believed to be more appropriate for systems involving gas hydrate equilibria than previous methods. Application of the proposed algorithm in several regions of the phase diagram of both binary and multicomponent systems shows that it can be used reliably to solve any phase equilibria problem, including the location of phase boundaries. In summary this work presents a consistent, efficient and reliable scheme for multiphase equilibrium calculations of systems containing reservoir fluids, water and methanol. Favourable results have been obtained by comparison with diverse experimental data reported in the open literature and it is believed that the proposed correlation can be used reliably for pipeline design and operation.
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Rickards, Andrew M. J. "Hygroscopic organic aerosol : thermodynamics, kinetics, and chemical synthesis." Thesis, University of Bristol, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.686238.
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Aerosols play a crucial role in many areas of scientific relevance including in new technologies to deliver medicine to the lungs, and in fuel injection and spray drying. Aerosols have a profound impact on the atmosphere, influencing radiative forcing both by scattering solar radiation and by influencing cloud properties. Organic aerosols are a major component, making up 20 - 90 % of the submicron mass by region, and are emitted from many natural and anthropogenic sources. This thesis presents new measurements of the hygroscopic behaviour of single organic droplets confined using two techniques: aerosol optical tweezers (AOT) and an electrodynamic balance (EDB). Values of the hygroscopicity parameter (K) are derived and added to a comprehensive literature survey to elucidate a relationship with droplet composition, in terms of the molecular ratio of oxygen to carbon atoms (OIC). These data are shown to be in broad qualitative agreement. However, variation in K for droplets of the same OIC is found to be significant, and discrepancies between subsaturated and supersaturated data are evident. The variabilities and uncertainties associated with characterising the kinetics of water transport in ultraviscous sucrose droplets are also presented. Droplets are exposed to a perturbation in relative humidity, and the resultant characteristic relaxation timescale (r) is determined from stimulated Raman spectra. Comparison of the experimental· evaporation data with simulated timescales shows excellent agreement, and r is shown to increase strongly with droplet radius. Qualitative agreement between experimental condensation data and simulated timescales is presented, and r is shown to increase with wait time (the time the perturbation is applied for). Finally, factors influencing the ability to perform controlled chemical synthesis in single droplets are investigated. The formation of Nylon-6,1 0 at the droplet-gas phase interface is used as a test case of the system, and the interplay between droplet volatility and reactivity is shown to be crucial for controlling the reaction. Further investigations demonstrate synthesis of picomolar concentrations (equivalent to a single dose) of a functionalised caprolactam anti-cancer drug. The challenges in reliably validating drug formation in aerosol are presented.
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Tamim, Jihane. "A continuous thermodynamics model for multicomponent droplet vaporization." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/mq20955.pdf.
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Khoshkbarchi, Mohammad Khashayar. "Thermodynamics of amino acids in aqueous electrolyte solutions." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=42068.
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A novel method has been developed for the measurement of the activity coefficients of an amino acid and the mean ionic activity coefficients of an electrolyte in water-electrolyte-amino acid systems. The method uses an electrochemical cell with two ion selective electrodes and a reference electrode. Activity coefficient data, at 298.15 K, for eight water-electrolyte-amino acid systems were measured. The cell consisted of a cation and an anion ion selective electrode, and the potential of each was measured versus a double junction reference electrode. The amino acids studied were glycine, DL-alanine, DL-valine and DL-serine and the electrolytes studied were NaCl and KCl. For the same systems, the solubilities at 298.15 K of the amino acids were measured at various electrolyte concentrations. The results show that the activity coefficients and the solubility of the amino acid in aqueous electrolyte solutions are strongly affected by the concentrations of both the electrolyte and the amino acid, the chemical structure of the amino acid and the nature of the cation of the electrolyte.The activity coefficients of amino acids in aqueous electrolyte solutions were modelled using a two-parameter excess Gibbs free energy model based on the contribution of a long range interaction term represented by the Bromley or the K-V model and a short range interaction term represented by the NRTL or the Wilson model.
A model based on the perturbation of a hard sphere reference system, coupled with a mean spherical approximation model, was also developed to correlate the activity coefficient of the amino acid and the mean ionic activity coefficient of the electrolyte in water-electrolyte-amino acid systems. The model can also predict the activity coefficients of amino acids in aqueous electrolyte solutions, without adjusting any parameter, at low electrolyte concentrations and slightly deviates from the experimental data at higher electrolyte concentrations.
A model was developed to correlate the solubilities of amino acids in aqueous and aqueous electrolyte solutions. The activity coefficients of amino acids in both aqueous and aqueous electrolyte solutions were represented by the perturbed mean spherical approximation model. It was shown that upon availability of independently evaluated experimental data for $ Delta h$ and $ Delta g$, the water-amino acid solubility model can accurately predict the solubility of amino acids in aqueous solutions without any adjustable parameter.
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Ferguson, Todd R. (Todd Richard). "Lithium-ion battery modeling using non-equilibrium thermodynamics." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/87133.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemical Engineering, 2014.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 147-161).
The focus of this thesis work is the application of non-equilibrium thermodynamics in lithium-ion battery modeling. As the demand for higher power and longer lasting batteries increases, the search for materials suitable for this task continues. Traditional battery modeling uses dilute solution kinetics and a fit form of the open circuit potential to model the discharge. This work expands on this original set of equations to include concentrated solution kinetics as well as thermodynamics-based modeling of the open circuit potential. This modification is advantageous because it does not require the cell to be built in order to be modeled. Additionally, this modification also allows phase separating materials to be modeled directly using phase field models. This is especially useful for materials such as lithium iron phosphate and graphite, which are currently modeled using a fit open circuit potential and an artificial phase boundary (in the case of lithium iron phosphate). This thesis work begins with a derivation of concentrated solution theory, beginning with a general reaction rate framework and transition state theory. This derivation includes an overview of the thermodynamic definitions used in this thesis. After the derivation, transport and conduction in porous media are considered. Effective transport properties for porous media are presented using various applicable models. Combining concentrated solution theory, mass conservation, charge conservation, and effective porous media properties, the modified porous electrode theory equations are derived. This framework includes equations to model mass and charge conservation in the electrolyte, mass conservation in the solid intercalation particles, and electron conservation in the conducting matrix. These mass and charge conservation equations are coupled to self-consistent models of the charge transfer reaction and the Nernst potential. The Nernst potential is formulated using the same thermodynamic expressions used in the mass conservation equation for the intercalation particles. The charge transfer reaction is also formulated using the same thermodynamic expressions, and is presented in a form similar to the Butler-Volmer equation, which determines the reaction rate based on the local overpotential. This self-consistent set of equations allows both homogeneous and phase separating intercalation materials to be modeled. After the derivation of the set of equations, the numerical methods used to solve the equations in this work are presented, including the finite volume method and solution methods for differential algebraic equations. Then, example simulations at constant current are provided for homogeneous and phase separating materials to demonstrate the effect of changing the solid diffusivity and discharge rate on the cell voltage. Other effects, such as coherency strain, are also presented to demonstrate their effect on the behavior of particles inside the cell (e.g. suppression of phase separation). After the example simulations, specific simulations for two phase separating materials are presented and compared to experiment. These simulations include slow discharge of a lithium iron phosphate cell at constant current, and electrolyte-limited discharge of a graphite cell at constant potential. These two simulations are shown to agree very well with experimental data. In the last part of this thesis, the most recent work is presented, which is based on modeling lithium iron phosphate particles including coherency strain and surface wetting. These results are qualitatively compared with experimental data. Finally, future work in this area is considered, along with a summary of the thesis.
by Todd R. Ferguson.
Ph. D.
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Cowles, Heather Jane. "Kinetics and thermodynamics of chemical reactions in aqueous solutions." Thesis, University of Leicester, 1990. http://hdl.handle.net/2381/34067.
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The kinetics of reaction and solvation properties of binary aqueous mixtures are discussed from different theoretical standpoints. Kinetic data are reported for reactions involving several Iron (II) complex cations in binary aqueous mixtures. The Savage-Wood Additivity Group Scheme (SWAG) is applied to kinetic data for the aquation of [Fe (5-nitro-1, 10-phenanthroline) 3]2+ in binary aqueous mixtures. Limitations of the theory are examined. The theory works well for reactions in alcohol-water and some carboxylic acid-water mixtures but not for reactions in urea-water and cyclic ether-water mixtures. The conclusion is reached that this theory can only be applied to relatively simple solutions. Otherwise, the assumptions made in the theory are not valid. Attention is then turned to the Kirkwood-Buff theory which can be applied to reactions in mixtures containing significant amounts of the cosolvent. Few assumptions are made in its derivation. This theory is used to probe the properties of a wide range of binary aqueous mixtures. Kinetic data describing reactions in these binary mixtures are then examined, leading to a consideration of preferential solvation. Finally, the possibility of monitoring chemical reactions under isochoric conditions is considered. A meaningful isochoric volume is defined. Kinetic and equilibrium reaction data are then analysed under these isochoric conditions.
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TORNATORE, LUCA. "HYDRODYNAMICAL SIMULATIONS OF GALAXY CLUSTERS: THERMODYNAMICS AND CHEMICAL ENRICHMENT." Doctoral thesis, Università degli studi di Trieste, 2005. http://thesis2.sba.units.it/store/handle/item/13085.
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Angevine, Christopher. "Nanopore thermodynamics via infrared laser heating." VCU Scholars Compass, 2017. https://scholarscompass.vcu.edu/etd/5200.
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Single molecule nanopore spectroscopy is a label-free method for characterizing a wide variety of water-soluble molecules. Recently there have been efforts to expand nanopore sensing to new areas of study. Forensic investigators require an easy to deploy method to identify an unknown number of contributors in a solution. Currently there is no easily available method to distinguish between a single or multiple contributor solution of DNA before being processed by more advanced analytical techniques which has led to wasted time and resources increasing the backlog of samples waiting to be processed. In this work we present a new nanopore technique capable of distinguishing between single and multiple contributors with an easy to deploy infrared heating laser. Previous cluster-nanopore enhancement interaction studies, produced by this group, have found that polymers in the presence of a gold-nanopore complex spend longer periods of time inside the pore. This is of great interest to the nanopore sensing community because longer residence times enable more accurate statistics on single polymers. In order to understand why x some polymers see large enhancements in the residence times (i.e. 20x) while other polymers see much less enhancement (i.e. 3x) a more complete picture of the free energy components is required. By using a IR heating laser, we construct an Eyring transition graph to extract the enthalpic and entropic energy components to find entropy plays a more important role than previously thought when a polymer interacts with a the nanopore. For nanoconfined polymers, entropy plays an important role on how a polymer will interact with the cluster-nanopore structure which in turn may lead to an increase or decrease of the residence time enhancement factor. This work shows with the addition of an infrared laser heater to a nanopore system a new tool has been added to the field. The IR laser coupled to a nanopore system allows for precise adjustments to residence times of events and extracts the free energy components without the need to physically modify the nanopore.
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Cheong, Ae-Gyeong. "Interfacial thermodynamics of liquid crystals : applications to capillary instabilities." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=84493.
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Most current applications and uses of liquid crystalline materials involve surfaces and interfaces. Prominent examples are high performance carbonaceous mesophase fibers, liquid crystal polymer fibers, and thermoplastic/liquid crystal polymer in-situ composites. Fundamental surface science and engineering principles are needed to optimize and design fibers and composites derived from liquid crystalline precursors. Currently non-equilibrium liquid crystal surface phenomena are not well understood. Force balance equations describing static and dynamical interfacial phenomena are available but have not been adequately used to describe the mechanics of fiber and film microstructures.This thesis explores the mechanics and stability of nematic liquid crystalline fibers embedded in inviscid and viscous matrices. A new theoretical framework for liquid crystal surface mechanics is formulated and used to model pattern formation and instability driven processes in fibers and fibrillar composites and blends. The liquid crystal Herring's formula and Laplace equation are derived and the role of liquid crystallinity is elucidated. In order to systematically analyze the role of the fundamental processes, linear stability analyses of capillary instabilities in nematic liquid crystalline fibers are performed by formulating and solving the governing nemato-capillary equations. An essential characteristic of liquid crystals, in contrast to isotropic liquids, is their mechanical anisotropy. Thus, the main parameters affecting the capillary instabilities are the isotropic and anisotropic surface tensions, the anisotropic viscosities, the bulk orientational elasticity, the isotropic viscosity of the matrix, and the surface bending modulus. Two asymptotic regimes are investigated: (a) the thin-fiber regime characterized by homogeneous bulk orientation and storage of surface elasticity, and (b) the thick-fiber regime characterized by bulk orientation distortions without surface elastic storage. Novel capillary instability mechanisms and symmetries of the instability modes for a nematic fiber embedded in a matrix are characterized. The predicted ability of capillary instabilities in nematic fibers to produce surface structures of well-defined symmetry and length scales, as well as chiral microstructures, is an important result that augments the pathways for targeted pattern formation. Deviations from classical Rayleigh capillary instabilities are identified and quantified in terms of liquid crystalline order.
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Smith, Raymond Barrett. "Nonequilibrium thermodynamics of porous electrodes for lithium-ion batteries." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/111406.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemical Engineering, 2017.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 147-170).
Lithium-ion batteries are increasingly important, both in portable electronic devices and as grid stabilization for intermittent renewable sources. The varied applications involve varying requirements for safety, lifetime, and energy/power density. The broad requirement space leads to a large design space, requiring either extensive and costly experimentation or effective models. To be predictive enough to facilitate design, models must be based on underlying physics. However, battery models commonly make assumptions known to be false, such as describing phase separating materials with Fickian diffusion. In this thesis, we build on existing battery models by modifying key parts to better capture fundamental phenomena including transport and reactions in phase separating materials. First, we introduce a model of lithium transport and surface reactions within particles of graphite, which has phase separation and is the most common anode material in lithium-ion batteries. We demonstrate key features of the model, including a sensitivity to its electrochemical reaction kinetics as well as its ability to capture both single particle and porous electrode experimental data. Second, we connect a model of electrochemical kinetics that is well-established in the chemistry community to nonequilibrium thermodynamics and apply it to materials with phase separating electrodes. We demonstrate that, although it shares some characteristics with a commonly used phenomenological model, it makes distinct predictions which agree with certain experimental results. Finally, we unify these single-particle models within a volume-averaged model to describe battery behavior at the scale of full porous electrodes. The developed model and simulation software have already been applied by other researchers to help explain behavior of batteries with phase separating materials.
by Raymond Barrett Smith.
Ph. D.
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Fesinmeyer, Robert Matthew. "Chemical shifts define the structure and folding thermodynamics of polypeptides /." Thesis, Connect to this title online; UW restricted, 2005. http://hdl.handle.net/1773/11621.
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Palandri, James L. "Applications of computed chemical equilibria /." view abstract or download file of text, 2000. http://wwwlib.umi.com/cr/uoregon/fullcit?p9986748.
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Thesis (Ph. D.)--University of Oregon, 2000.Typescript. Includes vita and abstract. Includes bibliographical references (leaves 374-384). Also available for download via the World Wide Web; free to University of Oregon users.
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Ribeiro, M. Gabriela T. C. "A study of the nature and everyday basis of undergraduates' thermodynamic ideas about some chemical reactions." Thesis, University of East Anglia, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278097.
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The nature of undergraduates' ideas about thennodynamics and the everyday basis of those ideas was investigated. A sample of fourteen Portuguese undergraduate students in their last year of university studies in physics and chemistry (teacher training) were interviewed individually about five chemical phenomena. The results showed that these students found it very difficult to use thermodynamic concepts to discuss real situations. The physical reality of the situation seemed to dominate thinking. The majority of the students used criteria based mainly on observable features or everyday notions. There was very little spontaneous use of thermodynamic concepts. It was found that non-science conceptions were persistent despite formal instruction in advanced chemistry the students had received. The second experiment investigated the everyday origin of the ideas the students used and how everyday experiences and meanings and formal instruction may have influenced these ideas. It was carried out by interviewing individually ten secondary school pupils (9th and 12th grades) and five adults. The results showed that the intuitive way of thinking about the physical world influences strongly what students learn about 'new', 'abstract' and 'scientific' ways of explaining what happens in nature. The comparison of the results of both experiments showed that there was close similarity between pupils' and university students' ideas. Several reasons were put forward as explanation: (i) students are more confident using criteria based on perceivable features (ii) the context of real phenomena makes the use of theoretical knowledge difficult (iii) students spend more time dealing with 'everyday meanings' than with 'scientific meanings' (iv) the concepts are abstract and (v) science uses words also used in ordinary speech. Implications for teaching are pointed out.
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Sabatini, Benjamin J. "Chemical composition, thermodynamics, and recycling : the beginnings of predictive behavioral modeling for ancient copper-based systems." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:91a4426b-8232-4f85-a39b-69e6c01c327c.
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In their attempts to understand the unwritten past of human technology and progression, archaeologists have borrowed aspects of the natural sciences to answer big questions. In one such pursuit, fundamental aspects of the sciences have been employed towards the chemical compositional analysis of copper-based artifacts, often to simply classify which is bronze, brass, or pure copper, and to explain why they are significant in limited space and time. This thesis takes the variety of identified metal types and compositions from these analyses and builds the beginnings of an ambitious thermodynamic model based on the accepted premise of consistent and widespread recycling of ancient metals over time. Following the laws of thermodynamics, in systems at equilibrium, the model predicts the outcome of metal losses over the course of ancient pyrometallurgical processes from molten systems through both volatilization and oxidation using rigorous and established mathematics and theory. Elemental loss likelihoods are modeled for all binary copper-based metals, using activity coefficients, and ternary copper and zinc-based systems, with the excess Gibbs free energy, respectively. The calculations are performed using custom-written software designed to account for hundreds of thousands of compositional permutations after the method described by Redlich and Kister (1948). The results of these calculations are given as activity (binary) and isoactivity (ternary) contour lines. Quantified tables for the oxidation and volatilization of elements from a copper melt at 1200 ºC and 1 atm are also given as rough indicators of element loss in ancient pyrometallurgical systems. A proof of concept of the models viability is also provided for binary Cu-M and ternary Cu-M-Zn (M = Ag, As, Au, Bi, Co, Fe, Ni, Pb, Sb, Sn, Zn), Cu-Sn-Pb, and Cu-Sb-As systems from the Late Bronze Age to post-medieval periods in Britain, which is based on several substantial artifact chemical datasets. For each ternary system, the interaction parameters used for higher-order calculations from the fitted behavior of each contributing binary systems are provided. Comparison of the calculated models to available experimental system assessments, and to published archaeological chemical datasets, show that in both respects the proposed modeling of ancient copper-based metal losses works. And given the near ubiquity of ancient metal use around the world, the consistency in metal production and recycling technology, and the chemical analyses available, this preliminary model can be applied virtually anywhere the technology for smelting and recycling existed. In addition to loss modeling, this thesis has the additional offshoots of predicting ancient furnace conditions based on the calculated behavior of interacting metals, and of the controlling thermodynamic factors in the ancient calamine process.
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Sozbilir, Mustafa. "A study of undergraduates' understandings of key chemical ideas in thermodynamics." Thesis, University of York, 2001. http://etheses.whiterose.ac.uk/14049/.
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Wagner, Katharina. "An Extension to Endoreversible Thermodynamics for Multi-Extensity Fluxes and Chemical Reaction Processes." Doctoral thesis, Universitätsbibliothek Chemnitz, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-146781.
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In this thesis extensions to the formalism of endoreversible thermodynamics for multi-extensity fluxes and chemical reactions are introduced. These extensions make it possible to model a great variety of systems which could not be investigated with standard endoreversible thermodynamics. Multi-extensity fluxes are important when studying processes with matter fluxes or processes in which volume and entropy are exchanged between subsystems. For including reversible as well as irreversible chemical reaction processes a new type of subsystems is introduced - the so called reactor. It is similar to endoreversible engines, because the fluxes connected to it are balanced. The difference appears in the balance equations for particle numbers, which contain production or destruction terms, and in the possible entropy production in the reactor. Both extensions are then applied to an endoreversible fuel cell model. The chemical reactions in the anode and cathode of the fuel cell are included with the newly introduced subsystem -- the reactor. For the transport of the reactants and products as well as the proton transport through the electrolyte membrane, the multi-extensity fluxes are used. This fuel cell model is then used to calculate power output, efficiency and cell voltage of a fuel cell with irreversibilities in the proton and electron transport. It directly connects the pressure and temperature dependencies of the cell voltage with the dissipation due to membrane resistance. Additionally, beside the listed performance measures it is possible to quantify and localize the entropy production and dissipated heat with only this one modelIn dieser Arbeit erweitere ich den Formalismus der endoreversiblen Thermodynamik, um Flüsse mit mehr als einer extensiven Größe sowie chemische Reaktionsprozesse modellieren zu können. Mit Hilfe dieser Erweiterungen eröffnen sich zahlreiche neue Anwendungsmöglichkeiten für endoreversible Modelle. Flüsse mit mehreren extensiven Größen sind für die Betrachtung von Masseströmen ebenso nötig wie für Prozesse, bei denen sowohl Volumen als auch Entropie zwischen zwei Teilsystem ausgetauscht werden. Für sowohl reversibel wie auch irreversibel geführte chemische Reaktionsprozesse wird ein neues Teilsystem - der "Reaktor" - vorgestellt, welches sich ähnlich wie endoreversible Maschinen durch Bilanzgleichungen auszeichnet. Der Unterschied zu den Maschinen besteht in den Produktions- bzw. Vernichtungstermen in den Teilchenzahlbilanzen sowie der möglichen Entropieproduktion innerhalb des Reaktors. Beide Erweiterungen finden dann in einem endoreversiblen Modell einer Brennstoffzelle Anwendung. Dabei werden Flüsse mehrerer gekoppelter Extensitäten für den Zustrom von Wasserstoff und Sauerstoff sowie für den Protonentransport durch die Elektrolytmembran benötigt. Chemische Reaktionen treten in der Anode und Kathode der Brennstoffzelle auf. Diese werden mit dem neu eingeführten Teilsystem, dem Reaktor, eingebunden. Mit Hilfe des Modells werden dann Wirkungsgrad, Zellspannung und Leistung einer Brennstoffzelle unter Berücksichtigung der Partialdrücke der Substanzen, der Temperatur sowie der Dissipation beim Protonentransport berechnet. Dabei zeigt sich, dass experimentelle Daten für die Zellspannung sowohl qualitativ als auch näherungsweise quantitativ durch das Modell abgebildet werden können. Der Vorteil des endoreversiblen Modells liegt dabei in der Möglichkeit, mit nur einem Modell neben den genannten Kenngrößen auch die abgegebene Wärme sowie die Entropieproduktion zu quantifizieren und den einzelnen Teilprozessen zuzuordnen
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Walton, S. Patrick (Stephen Patrick) 1973. "Thermodynamics and kinetics of antisense oligonucleotide hybridization to a structured mRNA target." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/43615.
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Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, February 2002.Includes bibliographical references (p. 165-178).
Antisense oligonucleotides have the potential to selectively inhibit the expression of any gene with a known sequence. Antisense-based therapies are under development for the treatment of infectious diseases as well as complex genetic disorders. Although there have been some remarkable successes, realizing this potential is proving difficult because of problems with oligonucleotide stability, specificity, affinity, and delivery. Each of these limitations has been addressed experimentally through the use of chemically-modified oligonucleotides and oligonucleotide conjugates, with much success in enhancing oligonucleotide efficacy. These early studies have shown that selection of target site, once considered a trivial problem, is critical to the success of antisense strategies. It has become clear that the efficacy of antisense oligonucleotides is a strong function of the structure of the target mRNA. Though single-stranded, RNA molecules are typically folded into complex three-dimensional structures, formed primarily by intramolecular Watson-Crick base-pairing. If an oligonucleotide is complementary to a sequence embedded in the three dimensional structure, the oligonucleotide may not be able to bind to its target site and exert its therapeutic effect. Because the majority of the structure of RNA molecules is due to Watson-Crick base-pairing, relatively accurate predictions of these folding interactions can be made from algorithms that locate the structure with the most favorable free energy of folding.
(cont.) Taking advantage of the predictability of RNA structures, this thesis addresses the problem of antisense target site selection, first from a theoretical and subsequently an experimental standpoint. A thermodynamic model to predict the binding affinity of oligonucleotides for their target mRNA is described and validated using multiple in vitro and cell-culture based experimental data sets. Subsequently, direct experimental comparisons with theoretical predictions are made on the well-characterized rabbit-[beta]-globin (RBG) mRNA, using a novel, centrifugal, binding affinity assay. The importance of the hybridization kinetics is also explored, as is the role of association kinetics in defining the rate of cleavage by the enzyme ribonuclease H (RNase H). Finally, the applicability of the model in identifying biologically active oligonucleotides is demonstrated.
by S. Patrick Walton.
Sc.D.
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Bulusu, Seshu Periah. "Comparison of the efficiency of a thermo-chemical process to that of a fuel cell process when both involve the same chemical reaction." [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-1554.
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Marla, Krishna Tej. "Molecular thermodynamics of nanoscale colloid-polymer mixures: chemical potentials and interaction forces." Available online, Georgia Institute of Technology, 2004, 2004. http://etd.gatech.edu/theses/available/etd-08102004-105655/.
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Thesis (Ph. D.)--Chemical Engineering, Georgia Institute of Technology, 2006.Dr. J. Carson Meredith, Committee Chair ; Dr. Charles A. Eckert, Committee Member ; Dr. Clifford L. Henderson, Committee Member ; Dr. Rigoberto Hernandez, Committee Member ; Dr. Peter J. Ludovice, Committee Member. Vita. Includes bibliographical references.
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Marla, Krishna Tej. "Molecular Thermodynamics of Nanoscale Colloid-Polymer Mixtures: Chemical Potentials and Interaction Forces." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/7604.
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Nanoscale colloidal particles display fascinating electronic, optical and reinforcement properties as a consequence of their dimensions. Stable dispersions of nanoscale colloids find applications in drug delivery, biodiagnostics, photonic and electronic devices, and polymer nanocomposites. Most nanoparticles are unstable in dispersions and polymeric surfactants are added generally to improve dispersability and control self-assembly. However, the effect of polymeric modifiers on nanocolloid properties is poorly understood and design of modifiers is guided usually by empirical approaches. Monte Carlo simulations are used to gain a fundamental molecular-level understanding of the effect of modifiers properties on the thermodynamics and interaction forces of nanoscale colloidal particles. A novel method based on the expanded ensemble Monte Carlo technique has been developed for calculation of the chemical potential of colloidal particles in colloid-polymer mixtures (CPM). Using this method, the effect of molecular parameters like colloid diameter, polymer chain length, colloid-polymer interaction strength, and colloid and polymer concentrations, on the colloid chemical potential is investigated for both hard-sphere and attractive Lennard-Jones CPM. The presence of short-chain polymeric modifiers reduces the colloid chemical potential in attractive as well as athermal systems. In attractive CPM, there is a strong correlation between polymer adsorption and colloid chemical potential, as both show a similar dependence on the polymer molecular weight. Based on the simulation results, simple scaling relationships are proposed that capture the functional dependence of the thermodynamic properties on the molecular parameters. The polymer-induced interaction forces between the nanoparticles have been calculated as a function of the above parameters for freely-adsorbing and end-grafted homopolymer modifiers. The polymer-induced force profiles are used to identify design criteria for effective modifiers. Adsorbing modifiers give rise to attractive interactions between the nanoparticles over the whole parameter range explored in this study. Grafted surface modifiers lead to attraction or repulsion based on the polymer chain length and grafting density. The polymer-induced attraction in both adsorbing and grafted modifiers is attributed primarily to polymer intersegmental interactions and bridging. The location of the thermodynamic minimum corresponding to the equilibrium particle spacing in nanoparticle-polymer mixtures can be controlled by tuning the modifier properties.
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Carson, Elin Mair Llywelyn. "A study of undergraduate students' understanding of selected concepts in chemical thermodynamics." Thesis, King's College London (University of London), 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.397643.
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Latino, Diogo Alexandre Rosa Serra. "Automatic learning for the classification of chemical reactions and in statistical thermodynamics." Doctoral thesis, FCT - UNL, 2008. http://hdl.handle.net/10362/1752.
Full textAbstract:
This Thesis describes the application of automatic learning methods for a) the classification of organic and metabolic reactions, and b) the mapping of Potential Energy Surfaces(PES). The classification of reactions was approached with two distinct methodologies: a representation of chemical reactions based on NMR data, and a representation of chemical reactions from the reaction equation based on the physico-chemical and topological features of chemical bonds.
NMR-based classification of photochemical and enzymatic reactions. Photochemical
and metabolic reactions were classified by Kohonen Self-Organizing Maps (Kohonen
SOMs) and Random Forests (RFs) taking as input the difference between the 1H
NMR spectra of the products and the reactants. The development of such a representation can be applied in automatic analysis of changes in the 1H NMR spectrum of a mixture and their interpretation in terms of the chemical reactions taking place. Examples of possible applications are the monitoring of reaction processes, evaluation of the stability of chemicals, or even the interpretation of metabonomic data.
A Kohonen SOM trained with a data set of metabolic reactions catalysed by transferases
was able to correctly classify 75% of an independent test set in terms of the EC
number subclass. Random Forests improved the correct predictions to 79%. With photochemical reactions classified into 7 groups, an independent test set was classified with 86-93% accuracy. The data set of photochemical reactions was also used to simulate mixtures with two reactions occurring simultaneously. Kohonen SOMs and Feed-Forward Neural Networks (FFNNs) were trained to classify the reactions occurring in a mixture based on the 1H NMR spectra of the products and reactants. Kohonen SOMs allowed the correct assignment of 53-63% of the mixtures (in a test set). Counter-Propagation Neural Networks (CPNNs) gave origin to similar results. The use of supervised learning techniques allowed an improvement in the results. They were improved to 77% of correct assignments when an ensemble of ten FFNNs were used and to 80% when Random Forests were used.
This study was performed with NMR data simulated from the molecular structure by
the SPINUS program. In the design of one test set, simulated data was combined with
experimental data. The results support the proposal of linking databases of chemical
reactions to experimental or simulated NMR data for automatic classification of reactions and mixtures of reactions.
Genome-scale classification of enzymatic reactions from their reaction equation.
The MOLMAP descriptor relies on a Kohonen SOM that defines types of bonds on the basis of their physico-chemical and topological properties. The MOLMAP descriptor of a molecule represents the types of bonds available in that molecule. The MOLMAP
descriptor of a reaction is defined as the difference between the MOLMAPs of the products and the reactants, and numerically encodes the pattern of bonds that are broken,
changed, and made during a chemical reaction.
The automatic perception of chemical similarities between metabolic reactions is required for a variety of applications ranging from the computer validation of classification systems, genome-scale reconstruction (or comparison) of metabolic pathways, to the classification of enzymatic mechanisms. Catalytic functions of proteins are generally described by the EC numbers that are simultaneously employed as identifiers of reactions, enzymes, and enzyme genes, thus linking metabolic and genomic information. Different methods
should be available to automatically compare metabolic reactions and for the automatic
assignment of EC numbers to reactions still not officially classified.
In this study, the genome-scale data set of enzymatic reactions available in the KEGG
database was encoded by the MOLMAP descriptors, and was submitted to Kohonen
SOMs to compare the resulting map with the official EC number classification, to explore
the possibility of predicting EC numbers from the reaction equation, and to assess the
internal consistency of the EC classification at the class level.
A general agreement with the EC classification was observed, i.e. a relationship between the similarity of MOLMAPs and the similarity of EC numbers. At the same time, MOLMAPs were able to discriminate between EC sub-subclasses. EC numbers could be assigned at the class, subclass, and sub-subclass levels with accuracies up to 92%, 80%, and 70% for independent test sets. The correspondence between chemical similarity of metabolic reactions and their MOLMAP descriptors was applied to the identification of a number of reactions mapped into the same neuron but belonging to different EC classes, which demonstrated the ability of the MOLMAP/SOM approach to verify the internal consistency of classifications in databases of metabolic reactions.
RFs were also used to assign the four levels of the EC hierarchy from the reaction
equation. EC numbers were correctly assigned in 95%, 90%, 85% and 86% of the cases
(for independent test sets) at the class, subclass, sub-subclass and full EC number level,respectively. Experiments for the classification of reactions from the main reactants and products were performed with RFs - EC numbers were assigned at the class, subclass and sub-subclass level with accuracies of 78%, 74% and 63%, respectively.
In the course of the experiments with metabolic reactions we suggested that the
MOLMAP / SOM concept could be extended to the representation of other levels of
metabolic information such as metabolic pathways. Following the MOLMAP idea, the pattern of neurons activated by the reactions of a metabolic pathway is a representation of the reactions involved in that pathway - a descriptor of the metabolic pathway. This reasoning enabled the comparison of different pathways, the automatic classification of pathways, and a classification of organisms based on their biochemical machinery. The three levels of classification (from bonds to metabolic pathways) allowed to map and perceive chemical similarities between metabolic pathways even for pathways of different
types of metabolism and pathways that do not share similarities in terms of EC numbers.
Mapping of PES by neural networks (NNs). In a first series of experiments, ensembles of Feed-Forward NNs (EnsFFNNs) and Associative Neural Networks (ASNNs) were trained to reproduce PES represented by the Lennard-Jones (LJ) analytical potential
function. The accuracy of the method was assessed by comparing the results of molecular dynamics simulations (thermal, structural, and dynamic properties) obtained from the NNs-PES and from the LJ function.
The results indicated that for LJ-type potentials, NNs can be trained to generate
accurate PES to be used in molecular simulations. EnsFFNNs and ASNNs gave better
results than single FFNNs. A remarkable ability of the NNs models to interpolate between distant curves and accurately reproduce potentials to be used in molecular simulations is shown.
The purpose of the first study was to systematically analyse the accuracy of different NNs. Our main motivation, however, is reflected in the next study: the mapping
of multidimensional PES by NNs to simulate, by Molecular Dynamics or Monte Carlo,
the adsorption and self-assembly of solvated organic molecules on noble-metal electrodes.
Indeed, for such complex and heterogeneous systems the development of suitable analytical functions that fit quantum mechanical interaction energies is a non-trivial or even impossible task.
The data consisted of energy values, from Density Functional Theory (DFT) calculations,
at different distances, for several molecular orientations and three electrode
adsorption sites. The results indicate that NNs require a data set large enough to cover
well the diversity of possible interaction sites, distances, and orientations. NNs trained with such data sets can perform equally well or even better than analytical functions.
Therefore, they can be used in molecular simulations, particularly for the ethanol/Au
(111) interface which is the case studied in the present Thesis. Once properly trained,
the networks are able to produce, as output, any required number of energy points for
accurate interpolations.
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Lewis, Amanda. "Fundamental studies of the chemical vapour deposition of graphene on copper." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/fundamental-studies-of-the-chemical-vapour-deposition-of-graphene-on-copper(f85feb54-5994-4201-b400-c622f4d7b216).html.
Full textAbstract:
The chemical vapour deposition (CVD) of graphene is the most promising route for production of large-area graphene films. However there are still major challenges faced by the field, including control of the graphene coverage, quality, and the number of layers. These challenges can be overcome by developing a fundamental understanding of the graphene growth process. This thesis contributes to the growing body of work on graphene CVD by uniquely exploring the gas phase chemistry and fluid flow in the hot-wall graphene CVD reactor. Firstly the reported parameter space for the hot-wall CVD of graphene on copper was mapped, informing the subsequent work and providing a resource for the wider community. A CVD reactor was constructed to extend this parameter space to lower pressures using methane as a carbon source, and the films were categorised using scanning electron microscopy, Raman spectroscopy and optical dark field microscopy. The latter showed particular promise as a rapid and non-destructive characterization technique for identifying graphene films on the deposition substrate. The gas phase equilibrium compositions were calculated across the parameter space, and correlations between the stabilities of various chemical species and the types of deposition were drawn. This laid a foundation for the remainder of the experimental work, which explored the effect of diluent gases and different feedstocks on the growth to understand the importance of the identified correlations. Diluent gases (argon and nitrogen) were added to the experimental conditions and the thermodynamic model, and were found to reduce the degree of coverage of the graphene films. This result shows that the CVD of graphene is sensitive to factors other than the thermodynamic state parameters, such as the fluid flow profile in the reactor and inelastic collisions between the higher mass diluent gases and the methane/hydrogen/copper system. Using a nitrogen diluent raises the equilibrium carbon vapour pressure and seems to allow larger graphene grains to form. This suggests that thermodynamic factors can contribute to the nucleation of graphene films. Varying the hydrocarbon feedstock and the process conditions indicated that the structure of the deposited carbon is closely related to the nucleation kinetics. Three nucleation regimes are associated with different types of deposition: homogeneous nucleation with amorphous carbon or soot; uncatalysed nucleation with multilayer deposition; and nucleation processes controlled by the copper substrate withpredominantly monolayer deposition. Changing the feedstock from methane to acetylene resulted in poorer graphene coverage, showing that thermodynamic control does not apply in the portion of the parameter space at the high temperatures and lowpressures most successfully used for the deposition of continuous graphene monolayers.
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Williams, Howard Mark. "Disorder in materials." Thesis, De Montfort University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.254680.
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Golmohammadi, Mojdeh. "Theory and simulation of thermodynamics and flow induced order in carbonaceous mesophase binary mixtures." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=97066.
Full textAbstract:
Carbonaceous mesophases (CMs) obtained from petroleum pitches and naphthalene precursors are mixtures of discotic nematic liquid crystals (DNLCs) employed to produce high performance carbon fibers (CFs). Natural pitches are usually polydisperse while synthetic ones are currently produced with very narrow molecular weight distributions.To design and control the final structure and mechanical properties of CFs three key parameters have to be considered: (i) characteristics of the raw material including the molecular weight, molecular interactions and the concentration of each species, (ii) the processing temperature and (iii) the extensional flow applied in the fiber spinning process. Experimental synthesis, processing, and characterization of CM materials are expensive due to the required equipment and operating conditions. Hence the computational modeling methodology adopted in this thesis is a cost effective tool for these novel materials. This thesis uses theory, mathematical modeling and computational simulations to characterize the effect of three above mentioned major factors on the orientational and molecular ordering behavior of a mixture of two monodisperse DNLCs, of relevance to the manufacturing of high performance CFs.The statistical mechanics Maier-Saupe model which effectively predicts the molecular ordering behavior of pure discotic systems is first extended to binary mixtures and then further extended to incorporate uniaxial extensional flow effects. Thermodynamic and thermo-rheological phase diagrams of binary lyotropic/thermotropic CM mixtures are predicted by this theory and partially validated by previous theoretical results and experimental observations. The generic thermo-rheological phase diagram which specifies the orientational structure of each component and their degree of molecular orientation under extensional spinning flow is obtained. X-ray diffraction intensity and orientational specific heat are also simulated in the present thesis, verified by available data and used as characterization tools for the orientation behavior of CM mixtures. In summary the thesis provides a new practical route for targeted structure-property relations for high performance CFs, through the chemistry and composition of the precursors, thus extending the traditional routes based on modifications of operating conditions and process geometry. At the fundamental level, the thesis presents the first dynamical model for DNLC mixtures. The models and results of the thesis are also applicable to rod-like systems under biaxial extensional flow, and DNLC under magnetic and electric fields.Les mésophases de carbone (CMs) obtenu à partir de précurseurs de bitume et de naphtalène sont des mélanges de cristaux liquides nématiques discotiques (DNLCs) utilisés pour produire les fibres de carbone (CF) à hautes performances. Le bitume naturel est généralement polydispersé tandis que celui qui est synthétique est présentement produit avec des distributions étroites du poids moléculaires.Afin de concevoir et de contrôler la structure finale et les propriétés mécaniques des CFs, trois paramètres importants doivent être pris en compte: (i) les caractéristiques de la matière première dont le poids moléculaire et les interactions moléculaires (ii) la température du processus et (iii) l'écoulement extensionnel appliqué dans le processus de filage de la fibre. La synthèse expérimentale, le traitement et la caractérisation des matériaux CM sont chers en raison de l'équipement et des conditions d'opérations requises. C'est pourquoi la méthode de modélisation numérique adoptée dans cette thèse est un outil rentable pour l'étude ces nouveaux matériaux.Cette thèse s'appuie sur la théorie, la modélisation mathématique et des simulations numériques pour caractériser l'effet de chacun des trois facteurs principaux, mentionnés ci-dessus, sur le comportement et l'orientation moléculaires d'un mélange de deux DNLCs monodispersés, relevant pour la fabrication de CFs à hautes performances.Le modèle de mécanique statistique de Maier-Saupe qui prédit efficacement l'arrangement moléculaire des systèmes discotiques purs est d'abord étendu aux mélanges binaires puis étendu afin d'incorporer les effets d'écoulement extensionnel uniaxiaux. Les diagrammes de phases de thermodynamique et de thermo-rhéologie des mélanges binaires de CM lyotrope / thermotrope prédis par cette théorie et partialement validée par les résultats théoriques et les observations expérimentales précédentes. Le diagramme de phase de thermo-rhéologie générique qui spécifie la structure d'orientation de chaque composant et leur degré d'orientation moléculaire sous extension est obtenu. L'intensité de la diffraction à rayon X ainsi que la chaleur spécifique orientée sont également simulées dans la présente thèse, vérifié par les données disponibles et utilisés comme outils de caractérisation du comportement d'orientation des mélanges de CM. En résumé, la thèse propose une nouvelle démarche pratique pour les relations ciblées propriété-structure pour les CFs à haute performance, grâce à la chimie et la composition des précurseurs, ainsi étendant les démarches traditionnelles basées sur des modifications de conditions d'exploitation et de la géométrie des processus. Au niveau fondamental, la thèse présente le premier modèle dynamique pour les mélanges DNLC. Les modèles et les résultats de cette thèse sont aussi applicables aux systèmes allongés sous écoulements extensionnel biaxial et sous l'effet de champs électriques et magnétiques.
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Wang, Xidong. "Synthesis of AlON and MgAlON Ceramics and Their Chemical Corrosion Resistance." Doctoral thesis, KTH, Materials Science and Engineering, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3120.
Full textAbstract:
In view of the excellent mechanical, chemical and opticalproperties, AlON (Aluminum oxynitride) as well as MgAlON(Magnesium Aluminum oxynitride) have drawn the attention ofmaterials scientists in past decades. In this thesis,thermodynamic properties, synthesis and corrosion resistance tooxygen and slag of AlON and MgAlON ceramics have beeninvestigated.
Gibbs energy of AlON and MgAlON with different compositionsand temperatures were estimatedby using thermodynamicquasi-parabola rule. Phase stability diagrams of Al-O-N andMg-Al-O-N systems at different conditions have been calculated.On the basis of thermodynamic analysis, AlON and MgAlONceramics were synthesized by hot-press sintering andcharacterized by XRD, TEM and HREM analyses. An X-raydiffraction standard file of MgAlON is suggested and sent toJCPDS.
The density of AlON synthesized was 3.63g/cm3, about 97.8% of its theoretical density. Thedensity of MgAlON is 3.55 g/cm3. Fracture toughness of AlON and MgAlON is 3.96 and4.06 MPa.m1/2. Three-point bending strength of AlON and MgAlONare 248 and 268 MPa, respectively, at room temperature andkeeps very high until 1723K. However the strength drops 189 and202 MPa for AlON and MgAlON, respectively, at 1723K. Thefracture section of AlON and MgAlON were examined and found tobe a mixed fracture of intercrystalline and cleavage fracturefor AlON and a mixed intercrystalline and transcrystallinefracture for MgAlON.
Oxidation experiments of AlON and MgAlON and a comparison ofthe oxidation behavior of AlON, MgAlON, O'SiAlON-ZrO2and NB-ZCM have been carried out. Undernon-isothermal oxidation conditions, oxidation of AlON exhibitstwo steps with a "S"-shaped curve due to the phasetransformation of oxidation product. As temperature increases,the oxidation product, γ -Al2O3formed at lower temperatures will transform intoα-Al2O3. Due to the differences in the molar volumesbetween α-Al2O3and γ -Al2O3, cracks are likely to be formed in the productlayer promoting further oxidation. MgAlON, O'SiAlON-ZrO2and NB-ZCM show only one step with paraboliccurves.
Isothermal oxidation experiments of AlON, MgAlON,O'SiAlON-ZrO2and NB-ZCM have been carried out in thetemperature range of 1373-1773K. At lower temperatures, MgAlONshows the best resistance to oxidation. But at highertemperatures, such as 1773K, AlON shows the best resistance tooxidation. O'SiAlON-ZrO2shows very good oxidation resistance in the lowtemperature range up to 1673K. But, as the temperature goes upabove 1673K, there is liquid phase produced during theoxidation process. Gas bubbles are also formed in the productlayer causing the flaking-off of some parts of the productlayer. Therefore its oxidation rate increases greatly astemperature rises to 1673K. In the case of BN-ZCM ceramics, dueto the evaporation of B2O3, the oxidation resistance seems to be poorest. Thechemical reaction activation energies for the initial stage ofoxidation of AlON, MgAlON, O'SiAlON-ZrO2and BN-ZCM are 218, 330, 260 and 254 kJ/molerespectively. And the activation energies at the laterdiffusion controlling stages are 227, 573, 367 and 289 kJ/molefor AlON, MgAlON, O'SiAlON-ZrO2and BN-ZCM respectively.
The roughness of the oxidation sample surfaces has beenmeasured by Atomic Force Microscope. As the temperatureincreases, the degrees of roughness of AlON and MgAlON surfacesincrease slightly due to the growth of crystal grain. Theroughness degree of BN-ZCM increases greatly because of theevaporation of B2O3. However the roughness of O'SiAlON-ZrO2decreases as the temperature increases from 1473Kto 1673K. The main reason is that the liquid phase (glass)produced during the oxidation process at high temperatures suchas 1673K and 1773K. The roughness degree of MgAlON, AlON,O'SiAlON-ZrO2and BN-ZCM are 234, 174, 75 and 63 nm respectivelyat 1473K, and 297, 284, 52 and 406 nm respectively at1673K.
Experiments of corrosion of AlON by CaO-MgO-"FeO"-Al2O3-SiO2slags were conducted in the temperature range of1693-1753K under static conditions as well as under forcedconvection. XRD, SEM-EDS and TEM analyses on the corrodedsamples were carried out.
The results showed that the diffusion was therate-controlling step in the initial stage of the corrosion.Thereafter, the slag formation (the product layer dissolvinginto the liquid slag) became more and more important. Thisaspect was further confirmed by fractal dimension analysis ofthe interface. The overall activation energy for the corrosionprocess with slag No.1 was evaluated to be 1002 kJ. Adding"FeO" to the slag greatly enhanced the corrosion rate probablydue to the reaction of the sample with "FeO".
Key words:AlON, MgAlON, Thermodynamics, Synthesis,Oxidation, Slag corrosion
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Biborski, Andrzej. "Chemical ordering kinetics and thermal vacancy thermodynamics in B2 binary intermetallics : simulation study." Praca doktorska, Strasbourg, 2010. http://www.theses.fr/2010STRA6196.
Full textAbstract:
Les alliages intermétalliques de structure B2 sont des matériaux prometteurs pour leurs propriétés physiques. Une concentration anormalement élevée de lacunes est observée dans les alliages B2 très ordonnés. Les sauts atomiques élémentaires ayant lieu via des sauts de lacunes, il est surprenant que la vitesse d’évolution de l’ordre est bien plus basse dans NiAl ordonné B2 – système où la concentration de lacunes est très haute – que dans le système L12 – Ni3Al où la concentration de lacunes est bien plus basse. Ce phénomène a souvent été expliqué par l’existence dans cette structure de défauts triples, où les lacunes sont en grande partie piégées sur le sous-réseau du nickel en corrélation avec des antisites de Ni (atomes de Ni sur le sous-réseau Al), avec deux lacunes pour un antisite. Le but général de cette thèse a été d’élaborer une méthodologie pour les simulations par méthode Monte-Carlo des cinétiques de transformation structurale de ces systèmes. Il a été nécessaire de développer un modèle thermodynamique qui permette de déterminer la concentration de lacunes d’équilibre – la dépendance en température de cette concentration ne pouvant plus être négligée. Des simulations Monte-Carlo cinétiques cohérentes peuvent ensuite être effectuées. Ces modélisations ont été faites avec un hamiltonien d’Ising et avec un hamiltonien multi-atomes de la méthode de l’atome entouré (embedded atom method). Les résultats obtenus sont en bon accord avec les observations expérimentales : l’évolution lente du système est due au manque d’efficacité statistique des sauts effectués (beaucoup d’aller-retours) après le premier stade rapide de génération des défauts triplesIntermetallics based on the B2 superstructure are very promising for their physical properties. An unusual high vacancy concentration is observed in highly ordered systems. Whereas elementary atomic jumps occur via a vacancy mechanism, surprisingly the rate of chemical ordering processes is much lower for B2 – NiAl superstructure – with relatively very high vacancy concentration – in comparison to the system with low vacancy concentration (L12 - Ni3Al). That phenomenon was often explained by the means of so called „triple defect” – where vacancies are mostly „trapped” on the Ni sub-lattice and correlated with creation of Ni antisites (Ni atoms residing on the Al sub-lattice), with statistically two vacancies per one antisite. The general aim of this thesis was to elaborate a methodology for kinetic simulations by Monte-Carlo methods of structural transformations in these systems. Therefore it was necessary to develop a thermodynamic model which allows finding equilibrium vacancy concentration – as the thermal dependency of vacancy concentration cannot be neglected. Consistent Kinetic Monte-Carlo simulations could be next realized. They were made using either an Ising-type Hamiltonian or the many body potentials of the Embedded Atom Method. The results are in good agreement with the experimental observations: the slow evolution of the system is due to the statistical inefficiency of jumps performed (many return jumps) after the extremely fast stage of generation of triple defects
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Mangwiro, John Knox. "Thermodynamics and kinetics of aresenic and antimony removal from copper by sodium based slags." Thesis, Imperial College London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266428.
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Abdel-Qader, Zainab. "The role of liquid mixing in evaporation of complex multi-component mixtures, modelling using continuous thermodynamics." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0017/MQ58435.pdf.
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Alexandridis, Paschalis. "Thermodynamics and dynamics of micellization and micelle-solute interactions in block-copolymer and reverse micellar systems." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/37749.
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Li, Yongfeng. "Nonlinear oscillation and control in the BZ chemical reaction." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26565.
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Thesis (Ph.D)--Mathematics, Georgia Institute of Technology, 2009.Committee Chair: Yi, Yingfei; Committee Member: Chow, Shui-Nee; Committee Member: Dieci, Luca; Committee Member: Verriest, Erik; Committee Member: Weiss, Howie. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Joshi, Suvid. "MIXED SURFACTANT SYSTEMS: THERMODYNAMICS AND APPLICATIONS IN METAL OXIDE IMPRINTING." UKnowledge, 2014. http://uknowledge.uky.edu/cme_etds/29.
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In this work we study mixtures of cationic surfactant (CTAB) and sugar based surfactant(s) (octyl beta-D-glucopyranoside (C8G1), dodecyl maltoside (C12G2) and octyl beta-D-xylopyranoside (C8X1)) to understand the non-ideal thermodynamic behavior of the mixtures of cationic and non-ionic surfactants in water and synthesis of imprinted materials. The thermodynamics of micellization, mixing and dilution of these systems are studied using Isothermal Titration Calorimetry (ITC) and the experimental data obtained are modeled with a pseudo-phase separation model with non-ideal mixing described by regular solution theory. It is shown that a model accounting for enthalpy of demicellization and enthalpy of dilution based on McMillan-Mayer model is able to fit ITC data set for CTAB-C8G1 system with varying mole fractions.
In addition to measuring non-ideal mixing behavior, mixtures of cationic and saccharide-based surfactants are of interest for the molecular imprinting of oxide materials. Mixtures of CTAB and either C8G1 or C8X1 are utilized to prepare nonporous adsorbent materials which act as selective adsorbents towards the headgroup of the saccharide surfactant. The approach is based on the Stöber silica particle synthesis process in which surfactants are added to soft particles present at the onset of turbidity to imprint their surface. This approach is shown to yield particles displaying selective adsorption for sugars with different number of carbons, but also provide enantioselective adsorption of targeted saccharides. Enantioselectivity of D-glucose, D-xylose and D-maltose is demonstrated by imprinting with C8G1, C8X1 and C12G2, respectively. The imprinting technique provides the first example of selective adsorption based on non-covalent imprinting of silica for sugars.
The mixed surfactant are also used to synthesize templated porous materials incorporating titanium which are used for epoxidation catalysis. The porous materials obtained have high surface area, uniform pore sizes in the mesopore range, and provided high selectivity and activity towards epoxidation of styrene. Titanosilicate thin films are also synthesized using cationic and saccharide surfactant mixtures to understand the incorporation of the titanium into the porous material. It is demonstrated that large amounts of isolated, tetracoordinated titanium sites can be incorporated into mesoporous silica-based materials via the complexation of the titanium precursor with a saccharide-based surfactant.
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Desch, Rebecca J. "Thermodynamics and Mass Transport of Biomolecule Adsorption onto Chromatographic Media." University of Cincinnati / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1382372858.
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Heese, Frank Patrick. "The thermodynamics, mechanism and kinetics of the catalytic conversion of propylene and water to diisopropyl ether over amberlyst 15." Doctoral thesis, University of Cape Town, 1998. http://hdl.handle.net/11427/9575.
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Bibliography: leaves 297-313.Diisopropyl ether (DIPE) was synthesised in a single step from a feed of propylene and water over Amberlyst 15 ion exchange resin catalyst. It was produced in a trickle bed reactor at pressures between 1 bar and 60 bar, at temperatures between 70°C and 160°C and at overall propylene to water ratios between 1:5 and 10:1. Reaction proceeded in the liquid phase within the catalyst particles. The only reactions that occurred in the system were the hydration of propylene to form isopropanol (IPA) , the alkylation of IPA with propylene to form DIPE and the bimolecular dehydration of IP A to form DIPE and water. No side reactions such as propylene oligomerisation were observed. Starting from a feed of propylene and water the primary reaction product was IPA. IPA was subsequently consumed in two secondary reactions which produced DIPE. DIPE was produced either by the alkylation of IPA with propylene or by the bimolecular dehydration of IPA. It was generally not possible to study the two DIPE formation reactions separately as they are linked via the propylene hydration reaction. All experimental data was thus reported in terms of a hydration rate and an etherification rate, the latter being the sum of the IPA alkylation and the bimolecular IPA dehydration rates.
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Adapa, Deekshitha. "Sorption of Benzene, Tolueneand Ethylbenzeneby Plasticized PEMA and PEMA/PMMA Sensing Films Using aQuartz Crystal Microbalance (QCM) at 298.15K." Scholar Commons, 2019. https://scholarcommons.usf.edu/etd/7720.
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Detection of volatile organic compounds (VOC’s) in the environment is important for human health and wellness. Long term exposure of certain VOC’s like benzene, toluene, ethylbenzene and xylene (BTEX) has a severe effect on human health. There are techniques such as gas chromatography, photo ionization, and mass spectroscopy that are time consuming, require gas sampling and are ineffective in real time sensing in air. Acoustic wave devices such as surface acoustic wave (SAW) devices can be used for sensing BTEX compounds in both vapor and liquid phase. The quartz crystal microbalance (QCM) is a low-frequency acoustic wave device, which can be used to characterize polymer film sensing quickly and easily by studying the sorption properties of BTEX compounds in them. In this work, thin films (~ 0.5 microns) of polymer/plasticizer blends are spin-coated on a 5MHz QCM for the detection of VOC’s. A polymer/plasticizer combination of poly (ethyl methacrylate) (PEMA) and a copolymer of poly (ethyl methacrylate) and poly (methyl methacrylate) (PEMA/PMMA) with di n-butyl phthalate (DBP), di-n-butyl sebacate (DBS) and n-butyl stearate (BS) are used for the detection of benzene, toluene and ethylbenzene in vapor phase. The working apparatus consists of a stream of solvent vapor diluted with nitrogen to an arbitrary concentration passing over the QCM oscillated to its resonant frequency. The sorption data are reported at 298.15 K in terms of activity as a function of weight fraction curves and are interpreted with the Flory-Huggins ternary model. The addition of plasticizer modifies the free volume properties of the polymer, thereby increasing diffusion and sensitivity of BTEX vapors. The plasticizer composition is tailored to 17.5%, for maximum sorption with minimal viscoelastic effects. The sorption and sensitivity of BTEX are interpreted and studied in terms of plasticizer type and concentration.
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Ozkan, Ibrahim Ali. "Thermodynamic model for associating polymer solutions." Diss., Available online, Georgia Institute of Technology, 2004:, 2004. http://etd.gatech.edu/theses/available/etd-05042004-142825/unrestricted/ozkan%5Fibrahim%5Fa%5F200408%5Fphd.pdf.
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Thesis (Ph. D.)--School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, 2005. Directed by Amyn S. Teja.Dr. Thomas H. Sanders, Committee Member ; Dr. Peter J. Ludovice, Committee Member ; Dr. J. Carson Meredith, Committee Member ; Dr. William J. Koros, Committee Member ; Dr. Amyn S. Teja, Committee Chair. Includes bibliographical references.
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Mi, Jian. "SiC Growth by Laser CVD and Process Analysis." Diss., Available online, Georgia Institute of Technology, 2006, 2006. http://etd.gatech.edu/theses/available/etd-04062006-135055/.
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Thesis (Ph. D.)--Mechanical Engineering, Georgia Institute of Technology, 2006.Lackey, W. Jack, Committee Chair ; Cochran, Joe K., Committee Member ; Danyluk, Steven, Committee Member ; Fedorov, Andrei G., Committee Member ; Rosen, David W., Committee Member ; Wang, Zhonglin, Committee Member.
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Atilhan, Mert. "High accuracy p-rho-t measurements up to 200 MPa between 200 K and 500 K using a compact single sinker magnetic suspension densimeter for pure and natural gas like mixtures." [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-1903.
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Sherman, Steven Randall. "Computer modeling and its application to problems in fluid phase equilibria." Diss., Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/10247.
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Al-Abbasi, Omar Abdulaziz. "Modeling the Non-Equilibrium Behavior of Chemically Reactive Atomistic Level Systems Using Steepest-Entropy-Ascent Quantum Thermodynamics." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/24069.
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Predicting the kinetics of a chemical reaction is a challenging task, particularly for systems in states far from equilibrium. This work discusses the use of a relatively new theory known as intrinsic quantum thermodynamics (IQT) and its mathematical framework steepest-entropy-ascent quantum thermodynamics (SEA-QT) to predict the reaction kinetics at atomistic levels of chemically reactive systems in the non-equilibrium realm. IQT has emerged over the last three decades as the theory that not only unifies two of the three theories of physical reality, namely, quantum mechanics (QM), and thermodynamics but as well provides a physical basis for both the entropy and entropy production. The SEA-QT framework is able to describe the evolution in state of a system undergoing a dissipative process based on the principle of steepest-entropy ascent or locally-maximal-entropy generation. The work presented in this dissertation demonstrates for the first time the use of the SEA-QT framework to model the evolution in state of a chemically reactive system as its state relaxes to stable equilibrium. This framework brings a number of benefits to the field of reaction kinetics. Among these is the ability to predict the unique non-equilibrium (kinetic) thermodynamic path which the state of the system follows in relaxing to stable equilibrium. As a consequence, the reaction rate kinetics at every instant of time is known as are the chemical affinities, the reaction coordinates, the direction of reaction, the activation energies, the entropy, the entropy production, etc. All is accomplished without any limiting assumption of stable or pseudo-stable equilibrium. The objective of this work is to implement the SEA-QT framework to describe the chemical reaction process as a dissipative one governed by the laws of quantum mechanics and thermodynamics and to extract thermodynamic properties for states that are far from equilibrium. The F+H2-->HF+H and H+F2-->HF+F reaction mechanisms are used as model problems to implement this framework.Ph. D.
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Anttila, Raimo. "Complexation thermodynamics of aluminum, beryllium, dioxouranium, and lanthanoids with ligands containing hard donor atoms." Oulu, Finland : Dept. of Chemistry, University of Oulu, 1992. http://catalog.hathitrust.org/api/volumes/oclc/35165443.html.
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Ochs, Leonard Ryder. "A statistical mechanical non-lattice coordination theory to describe the solution thermodynamics of polymer mixtures." Diss., The University of Arizona, 1993. http://hdl.handle.net/10150/186340.
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A theoretical model has been developed to advance the study of the thermodynamics of highly concentrated binary polymer solutions. This statistical mechanical theory was developed to allow the modeling of the molar Gibbs and Helmholtz free energies of mixing as well as the standard derived functions, such as the solvent and solute activities, and the molar enthalpies and entropies of mixing. Three major results have been generated from this work: (1) The polymer/solvent interactions can be partitioned into a coordination term, which leads to a configurational entropy, and an interaction energy of mixing term, which leads to the standard enthalpy of mixing; (2) The temperature dependence of the enthalpy of mixing yields an interaction energy of mixing which incorporates an additional entropy of mixing which is present for all types of systems, even athermal mixtures; and (3) The theory enables the use of experimentally obtained enthalpies of mixing to be used directly in the prediction of solvent activities, and experimentally determined solvent activities to be used as a predictor of the enthalpies of mixing without differentiating the experimental data. The theory was tested on fifteen binary systems. These systems had a range of physical property characteristics, from mixtures which can be considered almost ideal, to highly non-ideal athermal polymer solutions, to aqueous polymer solutions. The studied systems were; benzene/cyclopentane, benzene/cyclohexane, benzene/biphenyl, benzene/diphenylmethane, benzene/1,2-diphenylethane, cyclohexane/bicyclohexyl, n-hexane/n-hexadecane, toluene/polystyrene, chloroform/polystyrene, methylethylketone/polystyrene, cyclohexane/polystyrene, benzene/polypropylene glycol, benzene/polyethylene glycol, water/glucose, and water/polyethylene glycol. Parameters for each of these systems and components are tabulated. The experimental solvent activity data are graphed with the regression lines, and the experimental enthalpy of mixing data are graphed with the curves predicted from the solvent activity parameters. The average relative error of fit for the regression of the solvent activity data up to a polymer volume fraction of about 0.85 is less than ±0.0035, while for the entire solvent activity data set it is ±0.025. The average relative error of fit for the molar enthalpy of mixing predictions (excluding the water/PEG data) is less than ±0.005.
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Balonis, Magdalena. "The influence of inorganic chemical accelerators and corrosion inhibitors on the mineralogy of hydrated Portland Cement Systems." Thesis, University of Aberdeen, 2010. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=153269.
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The thermodynamic properties of chloride, nitrate and nitrite AFm hydrates have been determined. Investigations of solid solutions and thermodynamic calculations on the influence of these anions on mineralogical changes in cement paste were performed and compared with experiments. To calculate volume changes, densities of principal crystalline phases occurring in cement were critically assessed and tabulated, in some cases with addition of new data. Database was obtained by calculating densities from crystallographic data and unit cell contents. In hydrated cements, anion sites in AFm phase are potentially occupied by OH, SO4 and CO3 ions. C1, NO3 or NO2 ions readily displace hydroxide, sulfate and carbonate in the AFm structures. Nitrates and nitrites do not have ability to displace chloride from the Friedel’s salt (C1-AFm) though. The binding power of AFm for nitrite/nitrate/chloride was calculated and confirmed experimentally at 25°C. It was observed that presence of chloride, nitrate or nitrite alters the AFm/Aft balance and thereby affect the specific volume of paste solids. It was found that the success of nitrite as a corrosion inhibitor for protection of embedded steel arises from its “smart” behaviour. AFm normally stores and sequesters nitrite. If chloride ingress occurs in service, the AFm undergoes ion exchange, gaining chloride and forming Friedel’s salt, while releasing soluble nitrite ions to the pore fluid. As a result, the aqueous ratio of [NO2-]/[C1-] increases and remains within the passivation range for steel.
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Setiawan, Nico. "UNDERSTANDING THE THERMODYNAMICS AND ORAL ABSORPTION POTENTIAL OF PHARMACEUTICAL AMORPHOUS SOLID DISPERSIONS." UKnowledge, 2018. https://uknowledge.uky.edu/pharmacy_etds/85.
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Supersaturating drug delivery systems, such as amorphous solid dispersions (ASDs), have been used extensively to elevate the apparent solubility and oral bioavailability of poorly water-soluble drugs. However, despite the numerous examples of success in increasing solubility and oral bioavailability using ASDs, physical stability challenges remain as formulators seek to employ high drug loading for cost reduction and improved patient compliance. Therefore, stability in both the solid and solution state must be considered for ASDs to be successful. In the solid state, the drug must remain amorphous in the solid matrix throughout the shelf life of the product. Although excipients, such as polymers, have been known to stabilize the amorphous drug in the solid state, stresses encountered during manufacturing and fluctuations in storage conditions may have a detrimental impact on the physical stability of ASDs. Numerous studies have been performed on the impact of each process on ASD stability, yet the relative quantitative impact of each process with respect to the overall energetics landscape is not well understood.
Further, ASDs must dissolve after administration and maintain the intended supersaturation in the gastrointestinal (GI) tract during the GI transit time to achieve maximum oral absorption. In solution, the energetics advantage of the amorphous over the crystalline material is a “double-edged sword,” in that it produces not only a high absorption driving force but also an undesirable high crystallization potential. An approach to quantitatively measure the thermodynamic activity of amorphous materials is, thus, desirable. However, it is difficult to measure thermodynamic activity quantitatively, especially due to the speciation process induced by formulation excipients and endogenous materials. Hence, it is often difficult to assess the true enhancement in the absorption for a given ASD and to measure its crystallization tendency in solution. Overall, this dissertation aims to address the following:
1. The relative thermodynamics magnitude of various processes with respect to the crystallization energy associated with amorphous drugs
2. The development of a practical tool to measure the thermodynamic activity of amorphous materials over its crystalline counterpart in solution to assess the enhancement in absorption in the presence of excipients
3. The impact of measured thermodynamic activity on drug crystallization energetics in the presence of excipients
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Derivaux, Jean-Francois. "Stochastic thermodynamics of transport phenomena and reactive systems: an extended local equilibrium approach." Doctoral thesis, Universite Libre de Bruxelles, 2020. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/308809.
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Avec les progrès de la technologie, il est désormais devenu possible de manipuler des faibles quantités d’objets nanométriques, voire des objets uniques. Observer une réaction chimique de quelques centaines de molécules sur des catalyseurs, étudier le travail exercé lors du déploiement d’un brin d’ADN unique ou mesurer la chaleur émise par un unique électron dans un circuit électrique constituent aujourd’hui des actes expérimentaux courants. Cependant, à cette échelle, le caractère aléatoire des processus physiques étudiés se fait plus fortement ressentir. Développer une théorie thermodynamique à ces échelles nécessite d'y inclure de manière exhaustive ces fluctuations.Ces préoccupations et les résultats expérimentaux et théoriques associés ont mené à l’émergence de ce que l’on appelle aujourd’hui la thermodynamique stochastique. Cette thèse se propose de développer une approche originale à la thermodynamique stochastique, basée sur une extension de l'hypothèse d'équilibre local aux variables fluctuantes d'un système. Cette théorie offre de nouvelles définitions des grandeurs thermodynamiques stochastiques, dont l'évolution est donnée par des équations différentielles stochastiques (EDS).Nous avons choisi d'étudier cette théorie à travers des modèles simplifiés de phénomènes physiques variés; transport (diffusif) de chaleur ou de masse, transport couplé (comme la thermodiffusion), ainsi que des modèles de réactions chimiques linéaires et non-linéaires. A travers ces exemples, nous avons proposé des versions stochastiques de plusieurs grandeurs thermodynamiques d'intérêt. Une large part de cette thèse est dévolue à l'entropie et aux différents termes apparaissant dans son bilan (flux d'entropie, production d'entropie ou dissipation). D'autres exemples incluent l'énergie libre d'Helmholtz, la production d'entropie d'excès, ou encore les efficacités thermodynamiques dans le transport couplé.A l'aide de cette théorie, nous avons étudié les propriétés statistiques de ces différentes grandeurs, et plus particulièrement l'effet des contraintes thermodynamiques ainsi que les propriétés cinétiques du modèle sur celles-là. Dans un premier temps, nous montrons comment l'état thermodynamique d'un système (à l' équilibre ou hors d'équilibre) contraint la forme de la distribution de la production d'entropie. Au-delà de la production d'entropie, cette contrainte apparaît également pour d'autres quantités, comme l'énergie libre d'Helmholtz ou la production d'entropie d'excès. Nous montrons ensuite comment des paramètres de contrôle extérieurs peuvent induire des bimodalités dans les distributions d'efficacités stochastiques.Les non-linéarités de la cinétique peuvent également se répercuter sur la thermodynamique stochastique. En utilisant un modèle non-linéaire de réaction chimique, le modèle de Schlögl, nous avons calculé la dissipation moyenne, non-nulle, engendrée par les fluctuations du système. Les non-linéarités offrent aussi la possibilité de produire des bifurcations dans le système. Les différentes propriétés statistiques (moments et distributions) de la production d'entropie ont été étudiées à différents points avant, pendant et après la bifurcation dans le modèle de Schlögl.Ces nombreuses propriétés ont été étudiées via des développements analytiques supportés par des simulations numériques des EDS du système. Nous avons ainsi pu montrer la fine connexion existant entre les équations cinétiques du système, les contraintes thermodynamiques et les propriétés statistiques des fluctuations de différentes grandeurs thermodynamiques stochastiques.Over the last decades, nanotechnology has experienced great steps forwards, opening new ways to manipulate micro- and nanosystems. These advances motivated the development of a thermodynamic theory for such systems, taking fully into account the unavoidable fluctuations appearing at that scale. This ultimately leads to an ensemble of experimental and theoretical results forming the emergent field of stochastic thermodynamics. In this thesis, we propose an original theoretical approach to stochastic thermodynamics, based on the extension of the local equilibrium hypothesis (LEH) to fluctuating variables in small systems. The approach provides new definitions of stochastic thermodynamic quantities, whose evolution is given by stochastic differential equations (SDEs).We applied this new formalism to a diverse range of systems: heat or mass diffusive transport, coupled transport phenomena (thermodiffusion), and linear or non-linear chemical systems. In each model, we used our theory to define key stochastic thermodynamic quantities. A great emphasis has been put on entropy and the different contributions to its evolution (entropy flux and entropy production) throughout this thesis. Other examples include also the stochastic Helmholtz energy, stochastic excess entropy production and stochastic efficiencies in coupled transport. We investigated how the statistical properties of these quantities are affected by external thermodynamic constraints and by the kinetics of the system. We first studied how the thermodynamic state of the system (equilibrium \textit{vs.} non-equilibrium) strongly impacts the distribution of entropy production. We then extended those findings to other related quantities, such as the Helmholtz free energy and excess entropy production. We also analysed how some external control parameters could lead to bimodality in stochastic efficiencies distributions.In addition, non-linearities affect stochastic thermodynamics quantities in different ways. Using the example of the Schlögl chemical model, we computed the average dissipation of the fluctuations in a non-linear system. Such systems can also undergo a bifurcation, and we studied how the moments and the distribution of entropy production change while crossing the critical point.All these properties were investigated with theoretical analyses and supported by numerical simulations of the SDEs describing the system. It allows us to show that properties of the evolution equations and external constraints could strongly reflect in the statistical properties of stochastic thermodynamic quantities.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished
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Tanupabrungsun, Tanaporn. "Thermodynamics and Kinetics of Carbon Dioxide Corrosion of Mild Steel at Elevated Temperatures." Ohio University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1355328679.
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Goodman, Benjamin T. "Thermodynamic Property Prediction for Solid Organic Compounds Based on Molecular Structure." Diss., CLICK HERE for online access, 2003. http://contentdm.lib.byu.edu/ETD/image/etd300.pdf.
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Ahmed, Khawtar. "A PM-IRRAS study of the influence of surface potential on the kinetics and thermodynamics of bovine serum albumin (BSA) adsorption on a 316LVM stainless steel surface." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40824.
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ABSTRACT This thesis discusses the influence of surface charge (i.e. surface potential) on the kinetics and thermodynamics of bovine serum albumin (BSA) adsorption on a biomedical-grade 316LVM stainless steel surface. A technique of polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS) was efficiently employed for this purpose. The kinetics of BSA adsorption on the 316LVM surface was found to greatly depend on the surface potential. With an increase in surface potential towards more negative values, both the BSA initial adsorption rate and the saturated surface concentration of BSA also increase. Both effects were explained predominantly on the basis of replacement of well-ordered water molecules at the 316LVM/solution interface. Equilibrium experiments showed that the adsorption of BSA on the 316LVM surface is a highly spontaneous process, characterized by a highly negative apparent Gibbs energy of adsorption. The process was described using the Langmuir isotherm. With an increase in surface potential towards negative values, the apparent Gibbs energy of BSA adsorption also increases, as well as the saturated surface (monolayer) concentration. This effect was also explained on the basis of replacement of well-ordered water molecules at the 316LVM/solution interface. It was demonstrated that the adsorption of BSA on the 316LVM surface is a reversible process. The adsorbed BSA monolayer can be spontaneously desorbed at open circuit potential, but the kinetics of this process is slow. However, by cathodically polarizing the surface in the potential region of hydrogen evolution, the rate of the BSA desorption process can be significantly increased.Résumé Ce Mémoire discute de l‟influence de la charge de surface (i.e. potentiel de la surface) sur la cinétique et la thermodynamique de l‟adsorption du sérum de l‟albumine bovin (BSA) sur la surface d‟acier inoxydable de calibre biomédical. La technique de la spectroscopie de modulation de polarisation en réflexion infrarouge (PM-IRRAS) fut efficacement utilisée pour cet objectif. Il fut observé que la cinétique d‟adsorption du BSA sur une surface de 316LVM est fortement dépendante sur le potentiel de surface. Lorsque le potentiel de surface augmente, les valeurs de plus en plus négatives, le taux d‟adsorption initiale de BSA ainsique sa concentration de surface saturée croissent également. Les deux effets sont expliqués par le remplacement des molécules d‟eau bien ordonnées à l‟interface de la solution/316L VM. Les expériences d‟équilibre ont montré que l‟adsorption du BSA sur la surface 316L VM est un processus très spontané ; caractérisé par une forte apparente énergie d‟adsorption négative de Gibbs. Le processus fut décrit par l‟isotherme de Langmuir. Avec une augmentation du potentiel de surface vers des valeurs négatives, l‟énergie Gibbs apparente de l‟adsorption de BSA augmente également, ainsi que la concentration de la surface saturée (monocouche). Cet effet est aussi expliqué par le remplacement des molécules d‟eau bien ordonnées à l‟interface de la solution/316 L VM. Il fut démontré que l‟adsorption du BSA sur la surface 316L VM est un processus réversible. La monocouche adsorbée du BSA peut être spontanément désorbé (enlevé) avec le potentiel de circuit ouvert. Par contre, la cinétique de ce circuit est lente. Cependant, avec une polarisation cathodique de surface dans la région potentielle de l‟évolution d‟hydrogène, le taux du processus de désorption de BSA peut augmenter significativement.
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Mo, Yan. "Quantum dissipation theory with application to electron transfer : Protein folding kinetics and thermodynamics : a mean-field ising model /." View abstract or full-text, 2006. http://library.ust.hk/cgi/db/thesis.pl?CHEM%202006%20MO.
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