Theses and Dissertations at Montana State University (MSU)
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/733
Browse
10 results
Search Results
Item NMR characterization of unfrozen brine vein distribution and structure in frozen systems(Montana State University - Bozeman, College of Engineering, 2022) Lei, Peng; Chairperson, Graduate Committee: Sarah L. Codd; This is a manuscript style paper that includes co-authored chapters.The liquid vein network (LVN) that forms in the interface of ice crystals or particles exists in frozen porous media due to the freezing point depression. The distribution and structure of the LVNs are dynamic due to the ice recrystallization phenomenon. In ice alone, the LVNs formed by the ice crystal interfaces can be characterized as a porous medium in terms of surface to volume ratio (SV /) and the tortuosity (alpha).The presence of solid particles or ice-binding proteins (IBPs) make the frozen system much more complex. The research presented uses nuclear magnetic resonance (NMR) experimental techniques, including magnetic resonance imaging (MRI), relaxation and self-diffusion measurements, to study the development of the LVNs in complex frozen systems containing solid particles or IBPs. Poly-methyl methacrylate (PMMA) particles of diameters 0.4, 9.9, and 102.2 microns are used with brine solution concentrations of 15, 30, and 60 mM Magnesium chloride (MgCl 2) to simulate complex frozen systems. The dynamic rearrangement with time of LVNs can be studied as a function of temperature, MgCl 2 concentration, and PMMA particle size. The results indicate that small solid particles dominate the structure dynamics while in larger solid particle packed beds the solute effect dominates. This behavior is quantified by determination of SV / and alpha from NMR relaxation and diffusion data. Additionally, IBP produced from the V3519-10 organism isolated from the Vostok ice core in Antarctica is added to ice samples frozen from 30, 60 and 120 mM MgCl 2 solution to investigate its influence on LVNs over months of aging. The interplay of the solute and biological effects is complicated but it appears the biological effect is more pronounced at lower salt concentrations. The data provide a basis for eventual combination of salt, IBP and solid particulate studies. The result of MRI, relaxation and self-diffusion measurements indicate the inhibition of ice recrystallization as a function of particle size, MgCl 2 concentration and the presence of IBP. The non-invasive data presented along with calibration of the relaxation experiments with self-diffusion experiments, demonstrate the continued extension of NMR techniques developed from porous media to frozen porous media and ice LVN structure.Item Rheo-NMR of complex fluids under startup, steady state and large amplitude oscillatory shear(Montana State University - Bozeman, College of Engineering, 2021) Jayaratne, Jayesha S.; Chairperson, Graduate Committee: Joseph D. Seymour and Sarah L. Codd (co-chair); This is a manuscript style paper that includes co-authored chapters.Fluids are categorized as either simple or complex based on the intricacy of their structure and material response to deformation. Simple fluids composed of small molecules subject to deformation, readily flow with linear interaction dynamics with neighboring molecules. In contrast complex fluids like polymers, micelle solutions, colloidal gels and suspensions, composed of larger molecules or particulates alter the dynamics of individual constituents during deformation, requiring complicated constitutive models. Complex fluids are encountered daily, as they are found in consumer products such as food, pharmaceutical and personal care products. Knowing flow characteristics of these consumer products and their raw materials under industrially applicable deformations enables engineers to design efficient industrial processes and to formulate products to desired qualities. While classical rheology (the study of the flow and deformation of matter) techniques give good estimation of stress-strain bulk flow response, it fails to provide local flow information. Proton nuclear magnetic resonance (1H-NMR) has been used to measure spatially and temporally resolved velocities of fluids subject to mechanical deformation. This research field is known as 'Rheo-NMR' and is a novel flow measuring technique in that it is non-invasive and able to quantify three-dimensional velocity fields even of opaque fluids. Velocity responses of complex fluids like worm-like micelle solutions, yield stress fluids and shear thinning fluids were studied under varied mechanisms of deformation and were compared to the responses of simple Newtonian fluids. How local velocities of the fluids change over time when a steady shear is applied suddenly, how the velocity fields are affected on applying large oscillatory shear deformations and how using different shearing geometries impacts the local flow response were explored. Using Rheo-NMR techniques, experimental protocols to study spatio-temporal velocity fields of complex fluids were developed and data analysis methods for quantifying such measurements were established.Item Spatiotemporal mapping of oxygen in model porous media biofilms using 19 F magnetic resonance oximetry(Montana State University - Bozeman, College of Engineering, 2019) Simkins, Jeffrey William; Chairperson, Graduate Committee: Philip S. Stewart and Joseph D. Seymour (co-chair); Philip S. Stewart and Joseph D. Seymour were co-authors of the article, 'Spatiotemporal mapping of oxygen in a microbially-impacted packed bed using 19 F nuclear magnetic resonance oximetry' in the journal 'The journal of magnetic resonance' which is contained within this dissertation.; Philip S. Stewart, Sarah L. Codd and Joseph D. Seymour were co-authors of the article, 'Non-invasive imaging of oxygen concentration in a complex in vitro biofilm infection model using 19 F MRI: persistence of an oxygen sink despite prolonged antibiotic therapy' submitted to the journal 'Magnetic resonance in medicine' which is contained within this dissertation.; Philip S. Stewart and Joseph D. Seymour were co-authors of the article, 'Microbial growth rates and local external mass transfer resistance in a porous bed biofilm system measured by 19 F magnetic resonance imaging of structure, oxygen concentration, and flow velocity' submitted to the journal 'Biotechnology and bioengineering' which is contained within this dissertation.Biofilms, microbial aggregates anchored to a surface using a sticky matrix of metabolic products called extracellular polymeric substances (EPS), are the dominant form of bacterial life and are widespread in nature, from glaciers to hot springs. The transition from the planktonic state to a biofilm is associated with striking changes to microbial phenotype which confer unique, biofilm-specific properties to resident cells that have important implications for medicine, industry, and environmental study. Many of these properties are caused in large part by oxygen transport limitation, which arises due to restriction of fluid flow in cell aggregates and consumption of oxygen for respiration. The balance of reactive and diffusive processes establishes strong spatial gradients in oxygen concentration which lead to profound spatial heterogeneity in bacterial species composition, growth yield, antimicrobial susceptibility, and reaction kinetics, among other traits. However, despite the importance of oxygen gradients in a host of highly-relevant biofilm phenomena, quantification of oxygen profiles in biofilms is difficult, both in the field and the lab, with the gold standard of measurement, the microelectrode, having significant limitations. 19 F Nuclear Magnetic Resonance (NMR) oximetry, a magnetic resonance-based technique for oxygen quantification that has been used to characterize oxygen usage in blood tissues and tumors, exploits the linear dependence of spin-lattice relaxation rate R 1 on local oxygen partial pressure for fluorine nuclei in perfluorocarbon (PFC) phases. In the current work, we apply 19 F NMR oximetry to a model packed bed biofilm system to generate novel insights into microbial oxygen usage and to introduce a complimentary oximetry tool for biofilm experimenters. We develop methodology for the introduction and fixation of a fluorinated oxygen sensor to facilitate long-term oxygen monitoring. We use 19 F oxygen distribution measurements in compliment to traditional NMR methods to correlate fluid flow with growth rate, generate spatial maps of oxygen utilization rate, identify differences in oxygen utilization behavior between different species, characterize infection persistence during antibiotic therapy, mathematically model macroscale oxygen sink development, and quantify local mass transfer phenomena.Item Magnetic resonance studies of fluid transport in porous systems and medical devices(Montana State University - Bozeman, College of Engineering, 2017) Nybo, Elmira; Chairperson, Graduate Committee: Sarah L. Codd; Joseph D. Seymour (co-chair)This research describes the application of nuclear magnetic resonance (NMR) techniques for non-invasive investigation of fluid transport and hydrodynamics in porous systems and medical devices. NMR microscopy is used to obtain information about internal structures and transport properties in porous materials and opaque systems. Controlling dispersion within restricted pore spaces is of importance in a variety of applications including soil consolidation and dewatering and electromigration of solutes. NMR pulsed gradient stimulated echo (PGSTE) techniques combined with electroosmotic flow (EOF) are used to study diffusion and dispersion coefficients in model glass bead packs. The results show that significant EOF-induced backflow can cause structural changes and alter the flow. Understanding the transport of liquids in porous materials during the application of electrical field holds promise for solving problems involving the delivery of binding agents to infill the pore space in rigid cement-based structures via electroosmosis. NMR PGSTE techniques and micro-CT scan imaging were used to study fluid transport and structural changes in a hydrating cement paste in a closed cell. It is shown that EOF in closed cement paste samples caused a significant increase in macroscopic void volume compared to closed samples with no flow. Needleless connectors (NCs) are commonly used medical devices with complicated internal design that leads to flow complexity that may cause undesirable bacterial deposition and biofilm formation. Magnetic resonance imaging (MRI) is applied to acquire spatial velocity maps of fluid flow at various positions within the devices. MRI velocimetry is demonstrated as an effective method to quantify flow patterns and fluid dynamic dependence on structural features of NCs. Alginate and alginate-based materials find an increasing interest in environmental engineering as adsorbents for heavy metal recovery from aqueous solutions. A Ca 2+ and Cu 2+ containing fluid flow through calcium-based alginate gel has been visualized using NMR velocimetry. NMR indicated velocity changes in gel capillaries caused by ion exchange processes and followed gel structural changes. NMR microscopy is shown as an effective method to describe fluid transport and internal structural features in opaque porous systems and medical devices.Item Nuclear magnetic resonance studies of biofilm - porous media systems(Montana State University - Bozeman, College of Engineering, 2017) Kirkland, Catherine Mullinnix; Chairperson, Graduate Committee: Sarah L. Codd; Joseph D. Seymour (co-chair); Sarah L. Codd was a co-author of the article, 'Low-field borehole NMR applications in the near subsurface environment' submitted to the journal 'Vadose zone journal' which is contained within this thesis.; Randy Hiebert, Adrienne Phillips, Elliot Grunewald, David O. Walsh, Joseph D. Seymour and Sarah L. Codd were co-authors of the article, 'Biofilm detection in a model well-bore environment using low-field NMR' in the journal 'Groundwater monitoring and remediation' which is contained within this thesis.; Maria P. Herrling, Randy Hiebert, Andrew T. Bender, Elliot Grunewald, David O. Walsh and Sarah L. Codd were co-authors of the article, 'In-situ detection of subsurface biofilm using low-field NMR - a field study' in the journal 'Environmental science and technology' which is contained within this thesis.; Sam Zanetti, Elliot Grunewald, David O. Walsh, Sarah L. Codd and Adrienne J. Phillips were co-authors of the article, 'Detecting microbially-induced calcite precipitation (MICP) in a model well-bore using downhole low-field NMR' in the journal 'Environmental science and technology' which is contained within this thesis.; Jessica Weisbrodt, Catherine M. Kirkland, Nathan H. Williamson, Susanne Lackner, Sarah L. Codd, Joseph D. Seymour, Gisela Guthausen and Harald Horn were co-authors of the article, 'NMR investigation of water diffusion in different biofilm structures' submitted to the journal 'Biotechnology and bioengineering' which is contained within this thesis.Nuclear magnetic resonance (NMR) allows for in-situ non-invasive studies of opaque systems over a wide range of length and time scales, making the method uniquely suited to studies of biofilms and porous media. The research comprising this thesis uses NMR to explore biophysical, chemical, and transport properties within heterogeneous porous media systems at both a macro- and micro-scale. The macro-scale projects validate a low-field borehole NMR instrument to monitor field-scale environmental engineering applications like subsurface biofilms and microbially-induced calcite precipitation (MICP). Subsurface biofilms are central to bioremediation of chemical contaminants in soil and groundwater whereby micro-organisms degrade or sequester environmental pollutants like nitrate, hydrocarbons, chlorinated solvents and heavy metals. When composed of ureolytic microbes, subsurface biofilms can also induce calcite precipitation. MICP has engineering applications that include soil stabilization and subsurface barriers, as well as sealing of cap rocks and well-bore regions for carbon dioxide sequestration. To meet the design goals of these beneficial applications, subsurface biofilms and MICP must be monitored over space and time - a challenging task with traditional methods. The low-field borehole NMR tool recorded changes in the T 2 relaxation distribution where enhanced relaxation indicated biofilm accumulation in a sand bioreactor and in subsurface soil. Additionally, the tool was able to detect MICP in a sand bioreactor. The changed mineral surface of the sand lead to an increase in T 2 relaxation times. The complementary high-field NMR project investigated micro-scale internal structures and mass transport within biofilm granules used for wastewater treatment. Granular sludge, composed of spherical aggregates of biofilm grown without a carrier, is an innovative biological treatment method with the potential to vastly reduce the cost of wastewater treatment without sacrificing efficiency. Large gaps remain, however, in our understanding of the fundamental formation mechanisms and the factors that control granule activity and stability. Magnetic resonance imaging (MRI) identified heterogeneous internal structures within aerobic granular sludge where relaxation rates and diffusion coefficients vary. Ultimately, these results will help improve modeling for optimization of granular sludge wastewater treatment process design.Item Characterizing molecular dynamics of polymer glass and gel phase transitions as a function of time, temperature, and concentration using nuclear magnetic resonance(Montana State University - Bozeman, College of Engineering, 2016) Dower, April Marie; Chairperson, Graduate Committee: Joseph D. SeymourPolymers can be used for a variety of applications and impact many aspects of our lives. This thesis investigates the dynamics of polymer gel and glass transitions over different times, temperatures, and concentrations using nuclear magnetic resonance (NMR) with the goal of further understanding these important systems. A polymer/solvent system, hydroxypropylmethylcellulose acetate succinate (HPMCAS) and acetone, was examined using magnetic relaxation correlation and exchange experiments to characterize domains of different molecular mobility over various temperatures and concentrations. Diffusometry was employed to support the results of the 2D relaxometry experiments. A simple relaxometry method to determine glassiness was verified, and characteristic length scales of a polymer solution at different temperatures were quantified using both relaxation exchange methods and diffusion data. Glasslike dynamics were observed in gelled polymer systems above their glass transition temperatures. The thermal gelation properties of colloidal polymer dispersions and the effects of different formulations on dry film formation of a polymer mixture were studied as well. Aging and plasticizer effects were examined in the colloidal polymer dispersions using magnetic relaxation correlation experiments along with diffusion experiments to understand molecular dynamics, and it was concluded that pre-gelation particle aggregates were necessary for the systems to thermally gel. The final polymer study aimed to determine why a formulation using differently-substituted polymer produced dry films with dissimilar mechanical properties than another. Using relaxometry data and quantitative length scales acquired through relaxation exchange, it was found that one mixture retained larger domains of water upon dry film formation, allowing the film to be less brittle.Item Nuclear magnetic resonance studies of wormlike micelles in porous media(Montana State University - Bozeman, College of Engineering, 2016) Trudnowski, Jacob Donald; Chairperson, Graduate Committee: Jennifer BrownInterest of worm-like micelles (WLM) in porous media has grown in oil industries as a rock fracturing fluid due to its fluid rheology properties. Non-invasive techniques like NMR are ideal for observing and monitoring non-Newtonian fluids. This research presents data collected using NMR techniques with Cetyl trimethyl ammonium toluene (CTAT) wormlike micelles flowing through porous media. Deviations from Gaussian behavior in displacement distributions are quantified, and effects of WLM in fluid flowing through porous media was observed.Item NMR of HPMCAS/acetone mixtures to characterize concentration and temperature dependent molecular dynamics and inform SDD droplet drying models(Montana State University - Bozeman, College of Engineering, 2014) Williamson, Nathan Hu; Chairperson, Graduate Committee: Joseph D. SeymourHydroxypropyl methylcellulose acetate succinate (HPMCAS)-based spray-dried dispersions (SDDs) have been shown to offer significant bioavailability enhancement for drugs with low aqueous solubility. However, the impact of macroscale process conditions on microscale droplet drying and the impact of droplet drying history on SDD physical stability, dissolution performance and particle properties are not well understood. Mass transfer to the droplet surface is diffusion limited, and quantifying the mutual diffusivity over the solvent content and wet-bulb temperatures experienced during drying is crucial to modeling droplet drying. This research used nuclear magnetic resonance (NMR) to probe the concentration and temperature dependence of molecular scale interactions within binary systems of HPMCAS polymer and acetone. This data can be incorporated into SDD droplet drying models. Following the generalized droplet drying model of Handscomb and Kraft [1], a specific SDD modeling procedure was developed. A preliminary form was coded in MATLAB using the finite difference method to approximate the drying time-dependent solvent concentration profiles over the changing droplet radius based on the governing equation for mass conservation. Mixtures of HPMCAS with acetone and wet placebo SDD were tested using high-field NMR. Pulsed gradient stimulated echo (PGSTE) NMR experiments resolved self-diffusion of solvent and polymer. Solvent concentration dependence of the mutual diffusivity was related to a free-volume fit of the acetone self-diffusivity. Multidimensional T 1-T 2 correlation and T 2-T 2 exchange experiments separated proton populations based on correlations of spin-lattice T 1 to spin-spin T 2 relaxation times and discerned time-dependent mixing between T 2 populations. T 1 and T 2 relaxation times depend on the mediation of dipolar coupling by rotational motions; therefore these experiments indicate molecular rotational mobility. Temperature dependence of self-diffusivity and T 1-T 2 correlation measured within a rubbery as well as a glassy HPMCAS/acetone sample indicated that these measurements can determine the thermodynamic phase of polymer-solvent systems. Progression of the SDD droplet drying model and the fundamental aspect of the research on polyelectrolyte and polymer dynamics expanded the current knowledge of polymer glass transition behavior, network formation, and aging. This research demonstrates the potential use of NMR to characterize and quantify mobility and mass transfer of polymers and other pharmaceutically-relevant materials.Item Characterization of non-Newtonian fluids and fluid flow through biofilms in porous media using nuclear magnetic resonance(Montana State University - Bozeman, College of Engineering, 2013) Edden, Alexis Sanderlin; Chairperson, Graduate Committee: Jennifer Brown; Alexis B. Sanderlin authored and Sarah J. Vogt, Elliot Grunewald, Bridget A. Bergin, and Sarah L. Codd were co-authors of the article, 'Biofilm detection in natural unconsolidated porous media using a low-field magnetic resonance system' in the journal 'Environmental science & technology' which is contained within this thesis.The research presented in this thesis uses nuclear magnetic resonance (NMR) experiments to study biofilm growth in porous media and to characterize the effects of shear forces on a non-Newtonian fluid. An introduction to NMR is given to provide experimental background and an understanding of the data analysis, followed by an overview of polymers and biofilms. The next chapters describe the experiments and results for biofilm growth in two different model porous media. The final chapter provides analysis of shear forces on the non-Newtonian fluid polyacrylamide. Biofilms are formed when bacterial cells attach to a surface and begin to grow in a phenotypically altered state. Observation of biofilm growth in porous media poses significant challenges due to the heterogeneous nature of the biofilm and the opaque nature of the surfaces on which biofilms form. In the experiments presented, displacement-relaxation experiments were performed while a biofilm grew in a model porous media positioned in the magnet. Separate analysis of the flow characteristics of the biofilm phase and the bulk fluid phase was possible within the same data set. The results indicate that convective flow did not occur through the biofilm and that biofouling of the pore space resulted in faster bulk fluid flow through the channels. Natural geological matter contains magnetically susceptible materials such as iron-bearing minerals and cannot be analyzed with a high-field NMR system. A benchtop low-field NMR system was used to perform relaxation measurements on highly magnetic natural geological sand samples mixed with sand and biofilm from a sand column reactor. Shorter relaxation times in the biofouled sample indicated the presence of a biofilm, demonstrating that low-field NMR systems can be used in the natural environment to test for the presence of biofouling. Polyacrylamide is often used in high-shear applications such as enhanced oil recovery and wastewater treatment. These shear forces could affect the structure, and thus the function, of the polymer. Rheo-NMR, a combination of rheology and NMR, was used to study the velocity field for polyacrylamide solutions in a Rheo-NMR Couette device under different shear rates. The data shows that the polymer exhibits shear thinning behavior.Item Nuclear magnetic resonance studies of biological and biogeochemical processes(Montana State University - Bozeman, College of Engineering, 2013) Vogt, Sarah Jane; Chairperson, Graduate Committee: Joseph D. Seymour; Sarah L. Codd (co-chair); Brandy D. Stewart, Joseph D. Seymour, Brent M. Peyton, and Sarah L. Codd were co-authors of the article, 'Detection of biological uranium reduction' in the journal 'Biotechnology and bioengineering' which is contained within this thesis.; Alexis B. Sanderlin, Joseph D. Seymour, and Sarah L. Codd were co-authors of the article, 'Permeability of a growing biofilm in a porous media fluid flow analyzed by magnetic resonance displacement-relaxation correlations' in the journal 'Biotechnology and bioengineering' which is contained within this thesis.; Hilary T. Fabich was a main author, and Matthew L. Sherick, Joseph D. Seymour, Jennifer R. Brown, Michael J. Franklin, and Sarah L. Codd were co-authors of the article, 'Microbial and algal alginate gelation characterized by magnetic resonance' in the journal 'Journal of biotechnology' which is contained within this thesis.The research presented uses nuclear magnetic resonance (NMR) experimental techniques to study systems of geochemical and biological processes. This thesis first presents an introduction to the NMR experimental concepts and data analysis. Several experimental systems are then described in detail: biological reduction of uranium; biofilm growth in porous media; and solutions and gels of alginate, a polymer molecule commonly found in the biofilm polymeric matrix. Bioremediation of heavy metal contaminants such as uranium around nuclear waste storage sites is an important environmental problem. Uranyl (UO 2 ²+) is soluble in water, while uraninite (UO 2) precipitates as nanoparticles. Certain types of bacteria are able to use uranium as the electron acceptor and reduce uranyl ions to uraninite. The experiments presented used a solution of uranyl ions that was reduced by a sulfur reducing bacteria and were studied using images and relaxation measurements. The growth of biofilms in the subsurface may also be used for bioremediation. Biofilms form when bacteria attach to surfaces and then produce and live within a polymeric matrix known as the extracellular polymeric substance (EPS). Experiments were done on a biofilm grown through the pore structure of a model bead pack. During the biofilm growth, displacement-relaxation correlation experiments were performed which were able to separate the biofilm phase from the bulk fluid phase using relaxation information. The results presented show that during biofilm growth very little convective flow occurs through the biofilm phase, while pore clogging causes channeling that increases the flow through non-biofilm filled pores and increases hydrodynamic dispersion. The EPS matrix of a biofilm contains DNA, proteins, and biologically produced polymers. Some biofilms such as those produced by the bacteria Pseudomonas aeruginosa contain the polymer alginate. Three biologically produced alginates were compared: alginate produced by algae, alginate produced by P. aeruginosa FRD1153, and alginate produced by P. aeruginosa FRD1. A diffusive reaction gelation process was used to produce heterogeneous gels which were analyzed both during and after gelation. Homogeneous gels and solutions were studied using relaxation dispersion techniques. Differences in hydrogen exchange processes, polymer conformation, and gel structure were analyzed.