Browsing by Author "Maneval, James E."

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Magnetic resonance analysis of capillary formation reaction front dynamics in alginate gels
(2011-09) Maneval, James E.; Bernin, D.; Fabich, H. T.; Seymour, Joseph D.; Codd, Sarah L.
The formation of heterogeneous structures in biopolymer gels is of current interest for biomedical applications and is of fundamental interest to understanding the molecular level origins of structures generated from disordered solutions by reactions. The cation-mediated physical gelation of alginate by calcium and copper is analyzed using magnetic resonance measurements of spatially resolved molecular dynamics during gel front propagation. Relaxation time and pulse-field gradient methods are applied to determine the impact of ion front motion on molecular translational dynamics. The formation of capillaries in alginate copper gels is correlated to changes in translational dynamics.
Magnetic resonance measurements of flow-path enhancement during supercritical CO2 injection in sandstone and carbonate rock cores
(2014-10) Vogt, Sarah J.; Shaw, Colin A.; Maneval, James E.; Brox, Timothy I.; Skidmore, Mark L.; Codd, Sarah L.; Seymour, Joseph D.
Sandstone and carbonate core samples were challenged with a two-phase supercritical CO2 and brine mixture to investigate the effects of chemical processes on the physical properties of these rocks during injection of CO2. The experiments were monitored in real-time for pressure, temperature, and volumetric rate discharge. Pore geometry and connectivity were characterized before and after each experimental challenge using magnetic resonance (MR) imaging and two-dimensional MR relaxation correlations. Quartz arenite sandstone cores were largely unaffected by the challenge with no measurable change in effective permeability at moderate and high temperatures (~50 Â°C and ~95 Â°C) or brine concentrations (~1 g/L and ~10 g/L). In contrast, a carbonate core sample showed evidence of significant dissolution leading to a six-fold increase in effective permeability. MR images and relaxation measurements revealed a marked increase in the volume and connectivity of pre-existing pore networks in the carbonate core. We infer that the increase in permeability in the carbonate core was enhanced by focused dissolution in the existing pore and fracture networks that enhanced fast-flow paths through the core.
NMR relaxation measurements of biofouling in model and geological porous media
(2011-09) Codd, Sarah L.; Vogt, Sarah J.; Hornemann, Jennifer A.; Phillips, Adrienne J.; Maneval, James E.; Romanenko, K. R.; Hansen, L.; Cunningham, Alfred B.; Seymour, Joseph D.
Recently 2D nuclear magnetic resonance (NMR) relaxation techniques have been able to access changes in pore structures through surface and diffusion based relaxation measurements. This research investigates the applicability of these methods for measuring pore and surface changes due to biofilm growth in various model porous systems and natural geological media. Model bead packs of various construction containing 100 lm borosilicate and soda lime glass beads were used to demonstrate how changes in the measured relaxation rates can be used to non-invasively verify and quantify biofilm growth in porous media. However significant challenges are shown to arise when trying to implement the same techniques to verify biofilm growth in a natural geological media.
Quantifying NMR relaxation correlation and exchange in articular cartilage with time domain analysis
(2018-02) Mailhiot, Sarah E.; Zong, Fangrong; Maneval, James E.; Galvosas, Petrik; Seymour, Joseph D.
Measured nuclear magnetic resonance (NMR) transverse relaxation data in articular cartilage has been shown to be multi-exponential and correlated to the health of the tissue. The observed relaxation rates are dependent on experimental parameters such as solvent, data acquisition methods, data analysis methods, and alignment to the magnetic field. In this study, we show that diffusive exchange occurs in porcine articular cartilage and impacts the observed relaxation rates in T1-T2 correlation experiments. By using time domain analysis of T2-T2 exchange spectroscopy, the diffusive exchange time can be quantified by measurements that use a single mixing time. Measured characteristic times for exchange are commensurate with T1 in this material and so impacts the observed T1 behavior. The approach used here allows for reliable quantification of NMR relaxation behavior in cartilage in the presence of diffusive fluid exchange between two environments.
Quantifying NMR relaxation correlation and exchange in articular cartilage with time domain analysis
(2018-02) Mailhiot, Sarah E.; Zong, Fangrong; Maneval, James E.; June, Ronald K.; Galvosas, Petrik; Seymour, Joseph D.
Measured nuclear magnetic resonance (NMR) transverse relaxation data in articular cartilage has been shown to be multi-exponential and correlated to the health of the tissue. The observed relaxation rates are dependent on experimental parameters such as solvent, data acquisition methods, data analysis methods, and alignment to the magnetic field. In this study, we show that diffusive exchange occurs in porcine articular cartilage and impacts the observed relaxation rates in T1-T2 correlation experiments. By using time domain analysis of T2-T2 exchange spectroscopy, the diffusive exchange time can be quantified by measurements that use a single mixing time. Measured characteristic times for exchange are commensurate with T1 in this material and so impacts the observed T1 behavior. The approach used here allows for reliable quantification of NMR relaxation behavior in cartilage in the presence of diffusive fluid exchange between two environments.