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1
Yadav, Santosh. "The Energetics of Water Interactions with Adult and Neonatal Skin." University of Cincinnati / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1259080683.
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Sresht, Vishnu. "Molecular-thermodynamic and simulation-assisted modeling of interfacial energetics." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/107875.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemical Engineering, 2016.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 189-203).
The heterogeneous molecular interactions that operate at material interfaces control the efficiency of chemical engineering processes as diverse as adsorption, emulsification, heat exchange, and froth flotation. In particular, the process of colloidal self-assembly harnesses the rich tapestry of interactions that operate at several length scales, including van der Waals and electrostatic interactions, the hydrophobic effect, and entropic considerations, to drive the autonomous aggregation of simple building blocks into intricate architectures. This bottom-up approach has increasingly become the mainstay of the colloids community in its quest to design and fabricate increasingly complex soft-matter assemblies for pharmaceutical, catalytic, optical, or environmental applications. Accurately modeling and manipulating interfacial interactions across many different length scales is vital to optimizing the self-assembly and stability of colloidal suspensions. With the above background in mind, in this thesis, I illustrate the modeling of interfacial phenomena at a range of length scales, with a particular focus on utilizing a combination of computer simulations and molecular-thermodynamic theories to evaluate the free energies associated with the formation and reconfiguration of revolutionary colloidal systems, including dynamically-responsive colloids and two-dimensional nanomaterial suspensions. First, I examine the interplay between interfacial tensions during the one-step fabrication, and stimuli-responsive dynamic reconfiguration, of three-phase and four-phase complex emulsions. This fabrication makes use of the temperature-sensitive miscibility of hydrocarbon, silicone, and fluorocarbon liquids and is applied to both microfluidic and scalable batch production of complex droplets. I demonstrate that droplet geometries can be alternated between encapsulated and Janus configurations by judicious variations in interfacial tensions, as controlled via conventional hydrocarbon and fluorinated surfactants, as well as by stimuli-responsive and cleavable surfactants. Subsequently, I examine the molecular origins of the ability of surfactants to modulate the interfacial tensions at fluid-fluid interfaces, including developing a computer simulation-aided molecular- thermodynamic framework to predict the adsorption isotherms of non-ionic surfactants at the air-water interface. The use of computer simulations to evaluate free-energy changes is implemented to model a surfactant molecule possessing tumor-selective cytotoxicity. Utilizing potential of mean force calculations, I shed light on the preference of this anti-cancer drug for certain types of lipid bilayers, including advancing a hypothesis for the mechanism through which this drug induces apoptosis. I then utilize potential of mean force calculations to evaluate the formation of colloidal suspensions of two novel two-dimensional materials: phosphorene and molybdenum disulfide (MoS2). I focus on the correlations between the structural features of commonly-used solvents and: (1) their ability to intercalate between nanomaterial sheets and induce exfoliation, and (2) their effect on the energy barrier hindering the aggregation of the phosphorene and MoS2 sheets. The combination of simulation-based computation of the potential of mean force (PMF) between pairs of nanomaterial sheets, as well as the application of theories of colloid aggregation, offers a detailed picture of the mechanics underlying the liquid-phase exfoliation and the subsequent colloidal stability of phosphorene and MOS2 sheets in the commonly-used solvents considered. The agreement between the predicted and the experimentally-observed solvent efficacies provides a molecular context to rationalize the currently prevailing solubility-parameter-based theories, and for deriving design principles to identify effective nanomaterial exfoliation media.
by Vishnu Sresht.
Ph. D.
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Narayanan, Vindhya. "Non-equilibrium Thermomechanics of Multifunctional Energetic Structural Materials." Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7570.
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Shock waves create a unique environment of high pressure, high temperature and high strain-rates. It has been observed that chemical reactions that occur in this regime are exothermic and can lead to the synthesis of new materials that are not possible under other conditions. The exothermic reaction is used in the development of binary energetic materials. These materials are of significant interest to the energetic materials community because of its capability of releasing high heat content during a chemical reaction and the relative insensitivity of these types of energetic materials. Synthesis of these energetic materials, at nano grain sizes with structural reinforcements, provides an opportunity to develop a dual functional material with both strength and energetic characteristics.
Shock-induced chemical reactions pose challenges in experiment and instrumentation. This thesis is addressed to the theoretical development of constitutive models of shock-induced chemical reactions in energetic composites, formulated in the framework of non-equilibrium thermodynamics and mixture theories, in a continuum scale. Transition state-based chemical reaction models are introduced and incorporated with the conservation equations that can be used to calculate and simulate the shock-induced reaction process. The energy that should be supplied to reach the transition state has been theoretically modeled by considering both the pore collapse mechanism and the plastic flow with increasing yield stress behind the shock wave. A non-equilibrium thermodynamics framework and the associated evolution equations are introduced to account for time delays that are observed in the experiments of shock-induced or assisted chemical reactions. An appropriate representation of the particle size effects is introduced by modifying the initial energy state of the reactants. Numerical results are presented for shock-induced reactions of mixtures of Al, Fe2O3 and Ni, Al with epoxy as the binder.
The theoretical model, in the continuum scale, requires parameters that should be experimentally determined. The experimental characterization has many challenges in measurement and development of nano instrumentation. An alternate approach to determine these parameters is through ab-initio calculations. Thus, this thesis has initiated ab-initio molecular dynamics studies of shock-induced chemical reactions. Specifically, the case of thermal initiation of chemical reactions in aluminum and nickel is considered.
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Rossi, Luciano Fernando dos Santos. "Otimização energetica de redes de trocadores de calor industriais : aplicações em engenharias de petroleo, alimentos e quimica." [s.n.], 1995. http://repositorio.unicamp.br/jspui/handle/REPOSIP/265690.
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Orientador: Antonio Carlos BannwartTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
Made available in DSpace on 2018-07-20T08:34:29Z (GMT). No. of bitstreams: 1 Rossi_LucianoFernandodosSantos_D.pdf: 31189486 bytes, checksum: b5668903a52a4adff00b0520804c237d (MD5) Previous issue date: 1995
Resumo: Este estudo teve como objetivo a análise de processos industriais, os mais abrangentes possíveis, visando sua otimização do ponto de vista energético-econômico. Neste intento, buscou-se apresentar não apenas um único ponto de otimalidade, mas um conjunto de opções que permita a um decisor escolher a situação mais conveniente. No desenvolvimento deste estudo foram utilizados um conjunto de Métodos de Otimização, dentre os quais podem ser destacados a Metodologia Pinch de Recuperação de Energia, baseada em uma redistribuição de potenciais térmicos dentro do processo analisado, e os Métodos originários da Programação Matemática, em especial a Programação Linear. Analisou-se em profundidade o caso, relativo à lndúsrtria de refino de Petróleo, de uma etapa de Craqueamento Catalítico da Refinaria de Paulínia, da PETROBRÁS. Entretanto, o conjunto de procedimentos aplicados neste trabalho mostrou-se eficiente quando da análise de outros segmentos industriais, em particular das lndústrias Química, de Alimentos e Petroquímica, como apresentado no decorrer deste trabalho. Este estudo mostra que é perfeitamente possível fazer-se uma análise energética e uma avaliação econômica de sua implantação, de uma maneira muito satisfatória e rápida
Abstract: This work deals with the industrial process analysis, includingvarious types and sizes, looking for their optimization fiom the economic and energetic point of view. Not only a single point of optimality was searched but a set of options which could permit to a decision maker to choose the best situation in each case. ln the development of this study were utilized a set of Optimization Methods, among which it can be mentioned the "Pinch Point Methodology" to heat recovery in networks, which is based in a redistribution of the thermal potentials of the process analyzed, and the methods originated tfom the Mathematics Programming, in special the Linear Programming. A deep analysiswas made on the case relative to an oil refinery.More precisely a part ofthe catalytic cracking of the Paulinia's Oil Refinery of PETROBRAS. The set of procedures applied in this work, it can be shown efficient when the analysis is applied to other industrial branches, in particular in the Chemistry, Food and Petrochemistry industries, as shown in throughout this work. This study shows that is possible to make an energetic analysis and an economic cost evaluation on the implementationof a process, in a fast and sactisfatory manner
Doutorado
Termica e Fluidos
Doutor em Engenharia Mecânica
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Moran, E. B. "Selective separations at ion exchangers : thermodynamics and energetics." Thesis, Swansea University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.638228.
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The equilibrium uptake of four amino acids (glycine, isoleucine, threonine, tryptophan) of differing physico-chemical properties on two ion exchangers of differing surface chemistries was studied with the aim of assessing the importance of inter-molecular and surface interactions in the ion exchange process. Analysis of data showed that, under the conditions investigated, the ion exchange of amino acids at hydrogen form cation exchangers occurred via the uptake of amino acid zwitterions and subsequent protonation of amino acid molecules within the exchangers. Equilibrium isotherm analysis allowed the determination of the thermodynamic equilibrium constants for each combination of amino acid and ion exchanger. The affinity of the synthetic organic resin (Dowex 50W) for the hydrophobic amion acid (tryptophan) was highest and lowest for the hydrophilic amino acid (threonine). The cellulosic ion exchanger (SE 53) displayed lower selectivity for all the amino acids compared to the Dowex 50W resin. This behaviour is explained by considering the chemical properties of the amino acids and ion exchangers. The heats of exchange of the amino acids at these ion exchangers were obtained by titration microcalorimetry using a Thermometric 2277 Thermal Activity Monitor. An analysis procedure was developed to determine the standard thermodynamic functions (ΔGo, ΔHo, ΔSo) for each ion exchange process. Knowledge of these thermodynamic quantities provided further insight into the interactions that can occur, in addition to the electrostatic interaction, during the ion exchange process. The thermodynamic data indicated the most effective means of manipulating process solution conditions in order to increase the selectivity of an ion exchanger for a particular amino acid and also to maximise the degree of separation between amino acids from a binary mixture. The techniques and data analysis procedures described are likely to be of use in the development of bioseparation processes.
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Binnie, S. J. "Ab initio surface energetics : beyond chemical accuracy." Thesis, University College London (University of London), 2011. http://discovery.ucl.ac.uk/1318067/.
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Density functional theory (DFT) is the work–horse of modern materials modeling techniques, but scattered evidence indicates it often fails for important surface properties. This thesis investigates how DFT estimates of the surface energy (σ) and molecular adsorption energies of ionic systems are affected by the choice of exchange–correlation (xc) functional. Accurate diffusion Monte–Carlo (DMC) and quantum chemistry (QC) calculations are presented for these quantities showing marked improvement over DFT and agreement of much better than chemical accuracy. DFT estimates of σ are presented for the (001) surfaces of LiH, LiF, NaF and MgO. Five xc functionals, LDA, PBE, RPBE, Wu–Cohen and PW91 are used. A clear xc functional bias is demonstrated with σLDA > σWC > σPBE > σPW91 > σRPBE. To improve the picture detailed pseudopotential DMC calculations are presented for LiH and LiF. The lattice parameters and cohesive energies agree with experiment to better than 0.2 % and 30 meV respectively. For LiH novel all–electron DMC calculations are also presented showing significant improvement over pseudopotential DMC. Accurate all–electron Hartree–Fock calculations of σ for LiH(001) and LiF(001) are presented along with calculations of the LiF bulk using specially adapted Gaussian basis–sets. Combined with existing QC correlation estimates the bulk and surface properties of LiH and LiF show excellent agreement to both experiment and DMC and allow a longstanding disagreement between two experimental estimates for σLiF to be resolved. Finally the adsorption energy curve for water on LiH(001) is obtained by both DMC and incremental QC techniques leading to agreement of better than 10 meV. DFT and dispersion corrected DFT estimates are also presented highlighting the large xc functional dependence. Thus we demonstrate that is possible and necessary to obtain agreement between higher levels of theory and produce benchmark values beyond DFT.
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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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Al-Motasem, Al-Asqalani Ahmed Tamer. "Nanoclusters in Diluted Fe-Based Alloys Containing Vacancies, Copper and Nickel: Structure, Energetics and Thermodynamics." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-89355.
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The formation of nano–sized precipitates is considered to be the origin of hardening and embrittlement of ferritic steel used as structural material for pressure vessels of nuclear reactors, since these nanoclusters hinder the motion of dislocations within the grains
of the polycrystalline bcc–Fe matrix. Previous investigations showed that these small precipitates are coherent and may consist of Cu, Ni, other foreign atoms, and vacancies. In this work a combination of on–lattice simulated annealing based on Metropolis Monte Carlo simulations and off–lattice relaxation by Molecular Dynamics is applied in
order to determine the structure, energetics and thermodynamics of coherent clusters in bcc–Fe. The most recent interatomic potentials for Fe–Cu–Ni alloys are used. The atomic structure and the formation energy of the most stable configurations as well as their total and monomer binding energy are calculated.
Atomistic simulation results show that pure (vacancy and copper) as well as mixed (vacancy-copper, copper-nickel and vacancy-copper-nickel) clusters show facets which correspond to the main crystallographic planes. Besides facets, mixed clusters exhibit a core-shell structure. In the case of v_lCu_m, a core of vacancy cluster coated with copper atoms is found. In binary Cum_Ni_n, Ni atoms cover the outer surface of copper cluster.
Ternary v_lCu_mNi_n clusters show a core–shell structure with vacancies in the core coated by a shell of Cu atoms, followed by a shell of Ni atoms. It has been shown qualitatively that these core–shell structures are formed in order to minimize the interface energy
between the cluster and the bcc-Fe matrix. Pure nickel consist of an agglomeration of Ni atoms at second nearest neighbor distance, whereas vacancy-nickel are formed by a vacancy cluster surrounded by a nickel agglomeration. Both types of clusters are called quasi-cluster because of their non-compact structure. The atomic configurations of quasiclusters can be understood by the peculiarities of the binding between Ni atoms and vacancies. In all clusters investigated Ni atoms may be nearest neighbors of Cu atoms but never nearest neighbors of vacancies or other Ni atoms. The structure of the clusters found in the present work is consistent with experimental observations and with results of pairwise calculations. In agreement with experimental observations and with recent results of atomic kinetic Monte Carlo simulation it is shown that the presence of Ni atoms promotes the nucleation of clusters containing vacancies and Cu.
For pure vacancy and pure copper clusters an atomistic nucleation model is established, and for typical irradiation conditions the nucleation free energy and the critical size for cluster formation have been estimated. For further application in rate theory and object kinetic Monte Carlo simulations compact and physically–based fit formulae are
derived from the atomistic data for the total and the monomer binding energy. The fit is based on the structure of the clusters (core-shell and quasi-cluster) and on the classical capillary model.
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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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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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Powers, Daryl E. "Effects of oxygen on embryonic stem proliferation, energetics, and differentiation into cardiomyocytes." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/38963.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2007.Includes bibliographical references (p. 106-114).
Most embryonic stem (ES) cell research has been performed using a gas-phase oxygen partial pressure (pO2gas) of 142 mmHg, whereas embryonic cells in early development are exposed to cellular pO2 (pO2cell) values of about 0-30 mmHg. Murine ES (mES) cells were used as a model system to study the effects of oxygen on ES cell proliferation, phenotype maintenance, cellular energetics, and differentiation into cardiomyocytes. It was found that undifferentiated mES cells are capable of surviving and proliferating at pO2 conditions in the range of 0-285 mmHg, with only moderately decreased growth at the extremes in pO2 over this range. Oxygen levels had no effect on the maintenance of the undifferentiated phenotype during culture with the differentiation-suppressing cytokine leukemia inhibitory factor (LIF) in the culture medium, and low oxygen had, at most, a small differentiating-promoting effect during culture without LIF. Aerobic metabolism was used to generate approximately 60% of the energy required by undifferentiated mES cells at high pO2, but substantially smaller fractions when cells were oxygen starved. This shift from aerobic to anaerobic respiration occurred within 48 hr with minimal cell death.
(cont.) Oxygen was found to substantially affect the differentiation of mES cells into cardiomyocytes. Reduced pO2cell conditions strongly promoted cardiomyocyte development during the first 6 days of differentiation, after which oxygen primarily influenced cell proliferation. Using silicone rubber membrane-based dishes to improve oxygenation and an optimized cardiomyocyte differentiation protocol, it was possible to reproducibly obtain 60 cardiomyocytes per input ES cells and a cell population that was 30% cardiomyocytes following 11 days of differentiation. These results, obtained using a pO2gas of 7 mmHg during the first 6 days of differentiation, represent a 3-fold increase relative to those obtained with a pO2gas of 142 mmHg throughout differentiation. This work has shown that undifferentiated ES cells are able to adapt to their environmental pO2 and are relatively insensitive to its variations, whereas during differentiation oxygen affects cell fate decisions. Oxygen control can be used to improve directed ES cell differentiation into cardiomyocytes and oxygen may play a more important role in early embryonic development than heretofore appreciated.
by Daryl E. Powers.
Ph.D.
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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.
Full textAbstract:
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.
Full textAbstract:
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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Orr-Ewing, Andrew John. "Laser studies of reaction dynamics." Thesis, University of Oxford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302888.
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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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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.
Full textAbstract:
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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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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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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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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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.
Full textAbstract:
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.
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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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Mishra, Subrata H. "Structure and Energetics of RNA - Protein Interactions for HIV RREIIB Targeting Zinc Finger Proteins." unrestricted, 2008. http://etd.gsu.edu/theses/available/etd-06302008-144759/.
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Thesis (Ph. D.)--Georgia State University, 2008.Title from file title page. Markus W. Germann, committee chair; Kathryn B. Grant , W. David Wilson, committee members. Electronic text (147 p. : ill. (some col.)) : digital, PDF file. Description based on contents viewed Oct. 6, 2008. Includes bibliographical references.
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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.
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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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Peterson, Charles Campbell. "Accurate Energetics Across the Periodic Table Via Quantum Chemistry." Thesis, University of North Texas, 2015. https://digital.library.unt.edu/ark:/67531/metadc822822/.
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Greater understanding and accurate predictions of structural, thermochemical, and spectroscopic properties of chemical compounds is critical for the advancements of not only basic science, but also in applications needed for the growth and health of the U.S. economy. This dissertation includes new ab initio composite approaches to predict accurate energetics of lanthanide-containing compounds including relativistic effects, and optimization of parameters for semi-empirical methods for transition metals. Studies of properties and energetics of chemical compounds through various computational methods are also the focus of this research, including the C-O bond cleavage of dimethyl ether by transition metal ions, the study of thermochemical and structural properties of small silicon containing compounds with the Multi-Reference correlation consistent Composite Approach, the development of a composite method for heavy element systems, spectroscopic of compounds containing noble gases and metals (ArxZn and ArxAg+ where x = 1, 2), and the effects due to Basis Set Superposition Error (BSSE) on these van der Waals complexes.
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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.
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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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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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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.
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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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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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Biborski, Andrzej. "Chemical ordering kinetics and thermal vacancy thermodynamics in B2 binary intermetallics : simulation study." Praca doktorska, Strasbourg, 2010. http://www.theses.fr/2010STRA6196.
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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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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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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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Pagire, Sudhir K. "Novel Methods for Co-crystallisation." Thesis, University of Bradford, 2014. http://hdl.handle.net/10454/12841.
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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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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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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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