Theses and Dissertations at Montana State University (MSU)

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    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.
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    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.
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    Exploring exchange and transport dynamics in complex systems through nuclear magnetic resonance
    (Montana State University - Bozeman, College of Letters & Science, 2021) Nelson, Madison Lee; Chairperson, Graduate Committee: Joseph D. Seymour and Sarah L. Codd (co-chair); This is a manuscript style paper that includes co-authored chapters.
    Nuclear magnetic resonance (NMR) is uniquely qualified for non-invasive studies of systems providing insights into macro-, meso-, and microscale structures. NMR relaxation and diffusion methods are applied to characterize transport and magnetization exchange dynamics in various complex systems. These techniques are highly sensitive to molecular mobility restrictions which correlate to the ability to monitor thermodynamic phase transitions and changes in molecular environment. NMR diffusion and relaxation measurements are applied to characterize the effect of xylose on transport within zeolite beads. The ability for NMR to explore the transport phenomenon on multiple length and time scales is exploited to characterize how the introduction of xylose effects the transport structure of the bead. Eigenvector simulations of magnetization evolution within a coupled pore system during multidimensional NMR measurements, T1-T2 relaxation correlation experiments, allowed for insights into complex diffusion and exchange occurring within multiple systems. Additionally, multidimensional relaxation NMR measurements, in the form of varying echo-time spin-spin relaxation dispersion T2(tau) and spin-spin relaxation exchange T2-T2 experiments, are demonstrated to successfully characterize thermodynamic structural rearrangements of two natural straight-chained hydrocarbons and a natural wax. Temperature dependent magnetization exchange was found in both the longitudinal and transverse magnetization. The results indicate the ability of NMR relaxometry to detect magnetization exchange without mass or molecular exchange, also known as spin diffusion, including in the transverse magnetization. Spatial domain extent can be inferred from the exchange timescale and an estimate of the spin diffusion coefficient. NMR relaxometry methods were extended to glycerol behenate, a common pharmaceutical component. Glycerol behenate was decomposed into its three base components to explore how polymorphic structure and exchange depend on temperature within each pure lipid through T2(tau) and T2-T2 NMR relaxation experiments. These methods allowed for in-situ monitoring of thermodynamic dependent exchange across domains in addition to decoupling of transverse and longitudinal exchange. The results allow for calculation of exchange length scales across the micro- and mesoscales within the lipids. Ultimately, multidimensional NMR relaxometry is successfully demonstrated to be an effective technique for characterizing and monitoring structural changes in lipids across various phase transition temperatures and time and length scales.
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    NMR hydrophilic metabolomic analysis of bacterial resistance pathways using multivalent quaternary ammonium antimicrobials in Escherichia coli and Bacillus cereus exposed to DABCO and mannose functionalized dendrimers
    (Montana State University - Bozeman, College of Letters & Science, 2021) Aries, Michelle Lynne; Chairperson, Graduate Committee: Mary J. Cloninger; This is a manuscript style paper that includes co-authored chapters.
    Novel antibiotics developed using a new scaffold are needed to combat the rising tide of antibiotic resistant bacteria. Multivalent antibiotics are a relatively new approach that have the potential to greatly increase the efficacy of antibiotics while making it difficult for bacteria to develop resistance. Dendrimers are an attractive framework for the multivalent presentation of antibacterial moieties. Quaternary ammonium compounds (QAC) are a positively charged class of membrane disruptors that are attracted to the large negative charge on phospholipid membranes. Nuclear magnetic resonance (NMR) metabolomics is a quantitative method used for comparison of metabolic profiles of wild type and mutated bacterial samples, enabling the study of bacterial response to antimicrobials. Proton (1 H) NMR hydrophilic metabolomics was used to study gram-negative and gram-positive bacteria upon exposure to 1,4-diazabicyclo-2,2,2-octane (DABCO) with a 16-carbon chain tethered onto a mannose functionalized poly(amidoamine) (PAMAM) dendrimer (denoted as DABCOMD), a membrane disrupting multivalent QAC. Stock Escherichia coli (E. coli) (denoted as wild type) and DABCOMD mutated E. coli (denoted as mutants) were collected in the mid log and stationary phases. The same procedures were used for Bacillus cereus (B. cereus) as for E. coli samples (denoted as unchallenged), except that a DABCOMD challenged sample set was added (denoted as challenged). The challenged sample set procedures were identical to the unchallenged, except DABCOMD was included at 33 % of the MIC value in the growth media for growth curve acquisition and sample collection. The greatest differences observed between the metabolic profiles of the wild type and mutated E. coli samples and between the challenged and unchallenged B. cereus samples were in energy-associated metabolites and membrane-related pathways. The mutants in all sample types were associated with higher levels of spent energy molecules (including AMP and NAD+) and peptidoglycan related compounds (including N-acetylglucosamine). Overall, more changes were observed for B. cereus (gram-positive), especially in challenged mutant B. cereus samples, than for E. coli (gram-negative) samples. Since DABCOMD is a positively charged multivalent membrane disruptor, both B. cereus and E. coli mutated to garner protection by altering their peptidoglycan layer composition, which is energetically costly.
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    Transient and steady state Rheo-NMR of shear banding wormlike micelles
    (Montana State University - Bozeman, College of Engineering, 2020) Al Kaby (Al Qayem), Rehab Noor; Chairperson, Graduate Committee: Sarah L. Codd and Jennifer Brown (co-chair); Jayesha S. Jayaratne, Timothy I. Brox, Sarah L. Codd, Joseph D. Seymour and Jennifer R. Brown were co-authors of the article, 'Rheo-NMR of transient and steady state shear banding under shear stratup' in the journal 'Journal of rheology' which is contained within this dissertation.; Sarah L. Codd, Joseph D. Seymour and Jennifer R. Brown were co-authors of the article, 'Characterization of velocity fluctuations and the transition from transient to steady state shear banding with and without pre-shear in a wormlike micelle solution under shear startup by Rheo-NMR' submitted to the journal 'Journal of applied rheology' which is contained within this dissertation.
    Over many years, the combination of nuclear magnetic resonance (NMR) techniques with rheometry, referred to as Rheo-NMR has been used to study materials under shear noninvasively. Rheo-NMR methods can provide valuable information on the rheological responses of materials or their behavior by temporally and spatially resolved mapping of the flow field. In this thesis, 1D velocity profiles across the fluid gap of a Couette shear cell are recorded using Rheo-NMR velocimetry to investigate the wormlike micelles (WLMs) surfactant system under transient and steady state flow conditions. The WLM system was a solution of 6 wt. % cetylpyridinium chloride (CPCl) and sodium salicylate (NaSal) in 0.5 M NaCl brine which is well-known for its ability to exhibit a mechanical response during flow known as shear banding. The shear banding phenomena is simply defined as the splitting of the flow into two macroscopic layers, a high and low shear band bearing different viscosities and local shear rates. Elastic instabilities are well known to develop in the unstable high shear band and manifest as fluctuations in the 1D measurements. Recently, it has been suggested that 1D velocimetry alone cannot reveal information about those observed fluctuations in terms of a sequence of elastic instabilities and 2D or 3D measurements are required. In this thesis, new Rheo-NMR equipment and quantitative analysis are used to characterize those fluctuations and show that 1D velocity measurements still have the potential to provide valuable information about 3D flows. Transient and steady state shear banding was observed for a range of shear rates across the stress plateau and the impact of several flow protocols were studied. The evolution of the high, low, and true shear rates, as well as interface position with time after shear startup was used to evaluate changes in the kinetics of shear band formation as a function of applied shear rate and flow protocol. Ultimately, these results will help in understanding the correlation between the macroscopic flow field and the microscopic structure and dynamics of WLMs and can also be a way to gain information about the presence and the dynamic of secondary flow without the need of a 3D measurement.
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    Quantitative 1 H NMR analyses of immunometabolic modulation in human macrophages
    (Montana State University - Bozeman, College of Letters & Science, 2019) Fuchs, Amanda Lee; Chairperson, Graduate Committee: Valerie Copie; Sage M. Schiller was an author and Wyatt J. Keegan, Mary Cloud B. Ammons, Brian Eilers, Brian Tripet and Valerie Copie were co-authors of the article, 'Quantitative 1 H NMR metabolomics reveals distinct metabolic adaptations in human macrophages following differential activation' in the journal 'Metabolites' which is contained within this dissertation.; Sage M. Schiller was an author and Isaac R. Miller, Mary Cloud B. Ammons, Brian Eilers, Brian Tripet and Valerie Copie were co-authors of the article, 'Pseudomonas aeruginosa planktonic- and biofilm-conditioned media elicit divergent responses in human macrophages' submitted to the journal 'PLoS pathogens' which is contained within this dissertation.
    Macrophages are innate immune cells that are found ubiquitously in nearly all human tissues, where they support host innate and adaptive immune responses in an effort to maintain systemic homeostasis. They are inherently plastic in nature and can dramatically modulate their functional phenotype according to pathogen and microenvironmental stimuli. Previous studies have shown that macrophages are particularly important for the resolution of inflammation in acute wound healing, which is marked by a phenotypic transition of wound macrophages from pro-inflammatory to anti-inflammatory. Chronic, or non-healing, wounds, such as diabetic, pressure, and venous leg ulcers, feature a prolonged host inflammatory response due in part to aberrant wound macrophage behavior. Non-healing in chronic wounds has also been shown to be dependent upon the establishment of pathogenic biofilms, which are more resistant to host defense mechanisms than planktonic, or free-floating, bacteria. Therefore, investigating macrophage dysregulation in the presence of bacterial biofilms has gained considerable interest. Here, 1D 1 H NMR-based metabolomics was utilized to identify metabolic pathways that are differentially modulated following primary human monocyte-derived macrophage activation with pro-inflammatory or anti-inflammatory stimuli relative to resting macrophages. Metabolic profiling of inflammatory macrophages indicated a substantial increase in oxidative stress as well as a decrease in mitochondrial respiration. These metabolic profiles also provided evidence that inflammatory macrophages divert metabolites from de novo glycerophospholipid synthesis to inhibit oxidative phosphorylation. In addition, we investigated which metabolic pathways are differentially modulated following primary human monocyte-derived macrophage exposure to Pseudomonas aeruginosa planktonic- and biofilm-conditioned media. Metabolic profiling of PCM- and BCM-exposed macrophages indicated a significant depletion of intracellular glucose without elevation of downstream glycolytic products. These metabolic patterns suggest that PCM- and BCM-exposed macrophages potentially divert glycolytic intermediates towards inositol phosphate metabolism. Overall, our studies provide additional support to previous findings, generate novel results regarding metabolic modulation of human macrophages following activation and exposure to planktonic- vs. biofilm-conditioned media, and contribute new insight to the field of immunometabolism.
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    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.
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    Nuclear magnetic resonance studies to characterize phase transitions in porous systems
    (Montana State University - Bozeman, College of Engineering, 2018) Thrane, Linn Winsnes; Chairperson, Graduate Committee: Sarah L. Codd; Emily A. Berglund, James N. Wilking, David Vodak and Joseph D. Seymour were co-authors of the article, 'NMR relaxometry to characterize drug structural phase in a porous construct' in the journal 'Molecular pharmaceutics' which is contained within this thesis.; Sarah L. Codd and Joseph D. Seymour were co-authors of the article, 'Probing molecular dynamics during hydrate formation by high field NMR relaxometry and diffusometry' submitted to the journal 'Journal of magnetic resonance' which is contained within this thesis.; Ryanne L. Daily, Abby Thane, Catherine M. Kirkland, Evan R. McCarney, Robin Dykstra, Sarah L. Codd and Adrienne J. Phillips were co-authors of the article, 'Detecting microbially induced calcite precipitation in porous systems using low-field nuclear magnetic resonance relaxometry' submitted to the journal 'Environmental science & technology' which is contained within this thesis.
    Nuclear magnetic resonance (NMR) allows for in-situ non-invasive studies of a wide range of systems at microscopic time and length scales. NMR relaxometry and diffusometry techniques along with magnetic resonance imaging (MRI) are applied to explore and characterize various phase transitions in complex systems. NMR techniques are highly sensitive to the thermodynamic phase of the system as well as restrictions on molecular motion, and the ability to detect and monitor phase transitions non-invasively is of great interest for various industrial applications NMR frequency spectra and 1D T 2 relaxation measurements are used to characterize the presence of an amorphous drug and its liquid-solid phase transition. T 1- T 2 magnetic relaxation correlation experiments monitor the impact of long-time storage at high relative humidity on the drug in a porous silica tablet. The results indicate the ability of non-solid-state NMR to characterize crystalline and amorphous solid structural phases, and the potential for drug quality control by NMR methods. High resolution MRI along with T 1-T 2 magnetic relaxation correlation experiments and pulsed gradient stimulated echo (PGStE) NMR methods are demonstrated to characterize hydrate formation. MRI monitors the spatial heterogeneity of the system as well as local hydrate growth rates. Using T 1-T 2 correlation NMR and spectrally resolved diffusometry, the transition from mobile to restricted dynamics is observed simultaneously for both water and cyclopentane throughout the hydrate formation process. The combination of these MR techniques allows for exploration of the complex molecular dynamics involved in hydrate formation processes. Using a low-field NMR system, microbially induced calcite precipitation (MICP) processes in granular media are explored by means of 1D T 2 relaxation measurements. The 1D T 2 distributions allowed for in-situ monitoring of the mineral precipitation progress and indicates decrease in total pore volume and a significant change in the surface mineralogy of the granular media. The results confirm the potential for detailed characterization of MICP progression in engineering applications. Ultimately, NMR is demonstrated as an effective method for detecting, characterizing, and monitoring several distinct phase transitions at various time- and length-scales.
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    Diffusion and diffusive exchange are sensitive to the structure of cartilage as measured by nuclear magnetic resonance
    (Montana State University - Bozeman, College of Engineering, 2017) Mailhiot, Sarah Elizabeth; Chairperson, Graduate Committee: Ronald K. June II; Nathan H. Williamson, Jennifer R. Brown, Joseph D. Seymour, Sarah L. Codd and Ronald K. June were co-authors of the article, 'T1-T2 correlation and biopolymer diffusion within human osteoarthritic cartilage measured with nuclear magnetic resonance' in the journal 'Applied magnetic resonance' which is contained within this thesis.; Sarah L. Codd, Jennifer R. Brown, Joseph D. Seymour and Ronald K. June were co-authors of the article, 'Pulsed gradient stimulated echo (PGSTE) NMR shows spatial dependence of fluid diffusion in human stage IV OA cartilage' submitted to the journal 'Magnetic resonance in medicine' which is contained within this thesis.; Fangrong Zong, James E. Maneval, Ronald K. June, Petrik Galvosas and Joseph D. Seymour were co-authors of the article, 'Quantifying NMR relaxation correlation and exchange in articular cartilage with time domain analysis' submitted to the journal 'Journal of magnetic resonance' which is contained within this thesis.; James E. Maneval, Ronald K. June and Joseph D. Seymour were co-authors of the article, 'Relaxation exchange in human OA cartilage impacts the observable T 2 relaxation rates' submitted to the journal 'Magnetic resonance in medicine' which is contained within this thesis.
    Osteoarthritis (OA) is the deterioration of the tissue on the surface of the articulating joints in mammals. OA is the progression loss of articular cartilage. OA affects 50% of people over age 65 and is the leading cause of workplace disability. There is no cure for OA and the state of the art treatment is joint replacement. One limitation for treating OA is the difficulty of diagnosing OA before tissue failure. Magnetic Resonance Imaging (MRI) is capable of detecting early pathologic changes to cartilage but challenges remain. The goal of this work is to evaluate how parameters, specifically relaxation and diffusion, used for creating imaging contrast in MRI are affected by disease in naturally occurring human osteoarthritis. Nuclear Magnetic Resonance (NMR) is utilized to measure the diffusion and magnetic relaxation in human OA cartilage samples. Diffusion Weighted Imaging (DWI) is a proposed imaging mechanism for diagnosing OA. The hypothesis is that fluid diffusion is faster in diseased tissue than in healthy tissue. We show that diffusion of fluid increases when cartilage is damaged by enzymes, such as during OA. We also show that the diffusion of fluid is donor specific in human OA cartilage. Diffusion of proteins in cartilage is also sensitive to enzyme degradation and donor as well as to the size and structure of the proteins in cartilage. These are complementary measures of the fluid and solid phase of cartilage. Relaxation weighted imaging is the most common way to image cartilage and is capable of measuring small structure changes due to OA. One limitation of this method is that reported relaxation rates vary between studies. We show that exchange, or motion of fluid, between the two sites of relaxation in cartilage alters the observed relaxation. Further, we show that the exchange rate is sensitive to donor and enzyme degradation. The results suggest that exchange rate is a sensitive measure of structure in cartilage and that relaxation should be cautiously interpreted when exchange occurs. Overall, this work shows that NMR and MRI are sensitive to the structure of cartilage and capable of detecting pathological damage to cartilage.
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    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.
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