Physical Sciences and Mathematics Commons^™

Mapping Gadolinium Contrast In A Complex Ionic And Photosynthesis Environment Of Pineapple By Near-Infrared And X-Ray Imaging, Subhendra Sarkar, Zoya Vinokur, Chen Xu, Tetiana Soloviova, Amina Shahbaz, Aldona Gjoni

Publications and Research

This work explores the diffusivity of a lanthanide complex, Eovist (Gadolinium-Ethoxy Benzyl Diethylenetriamine pentaacetate) that is stable in neutral media but is not in acidic environment. In the current work an acidic fruit model like pineapple that is rich in transition metals was used and a possible transmetallation reaction among Eovist and transition metal complexes was tested using X-ray imaging. Another goal of this work was to perturb the usual and the unusual photosynthesis systems that pineapple has maintained for millions of years during the evolution of circadian genes for efficient water conservation by dark photosynthesis. To detect such photosynthesis …

Temperature And Salinity Distributions And Flushing Time Estimates In A Low-Inflow California Estuary, Sydney N. Wewerka

Physics

This study examines the temperature and salinity distributions in Morro Bay, a small, seasonally LIE located on the central coast of California. In Morro Bay, eelgrass (Zostera marina; a temperate seagrass), like all seagrasses, is a critical habitat-forming species that supports a large variety of invertebrate, fish, and bird species in the estuary (MBNEP, 2018). Since 2007, eelgrass in the estuary has declined by over 90%, with most losses occurring in the back regions (i.e., head) of the estuary (MBNEP, 2018). Near the mouth, eelgrass meadows have remained resilient, indicating that gradients in environmental conditions throughout the bay may be …

Experiment And Simulation Of Single-Molecule Recycling, Bo Wang

Doctoral Dissertations

This dissertation presents theoretical, numerical, and experimental research into a technique for extending the observation time of a single molecule in solution, while also enabling measurement of its diffusion coefficient. A confocal microscope is used to observe the fluorescently labelled molecule in aqueous solution, which is confined within a nanochannel. By focusing a laser beam into the nanochannel and applying electrokinetic flow along the tube, a molecule passes through the laser beam and emits a burst of photons. The molecule then passes back and forth through the focus while the voltage is repeatedly reversed at a fixed delay after each …

Using Bromide Tracer To Measure Uranium Diffusivity In Ground Water Sediments, Francis Michael Tee, Morris E. Jones, Megan K. Dustin, Sharon Bone, John Bargar

STAR Program Research Presentations

More than 129 million liters of groundwater are contaminated with uranium at Old Rifle, Colorado – a former uranium-processing site that operated until 1958. The original Department of Energy (DOE) strategy for remediation, involving natural flushing of U from the groundwater through mixing with surface water, has not proven successful. Thin pockets of silt-, clay-, and organic-rich sediments referred to as naturally reduced zones (NRZs) act both as sinks and sources of U to the aquifer, contribute to plume persistence, and appear to be diffusion limited controlled.

To better understand how the NRZs are diffusion limited controlled, a bromide tracer …

Reconstructing Thermal Properties Of Firn At Summit, Greenland, From A Temperature Profile Time Series, Alexandra L. Giese, Robert L. Hawley

Dartmouth Scholarship

We have constrained the value for thermal diffusivity of near-surface snow and firn at Summit Station, Greenland, using a Fourier-type analysis applied to hourly temperature measurements collected from eight thermistors in a closed-off, air-filled borehole between May 2004 and July 2008. An implicit, finite-difference method suggests that a bulk diffusivity of ∼25 ± 3m2 a−1 is the most reasonable for representing macroscale heat transport in the top 30 m of firn and snow. This value represents an average diffusivity and, in a conduction-only model, generates temperature series whose phase shifts with depth most closely match those of the Summit borehole …

Voigt, Reuss, Hill, And Self-Consistent Techniques For Modeling Ultrasonic Scattering, Christopher M. Kube, Joseph A. Turner

Department of Mechanical and Materials Engineering: Faculty Publications

An elastic wave propagating in a metal loses a portion of its energy from scattering caused by acoustic impedance differences existing at the boundaries of anisotropic grains. Theoretical scattering models capture this phenomena by assuming the incoming wave is described by an average elastic moduli tensorC_0ijkl (x) that is perturbed by a grain with elasticityC_ijkl (x ') where the scattering event occurs when x = x’. Previous models have assumed that C_0ijkl (x) is the Voigt average of the singlecrystal elastic moduli tensor. However, this assumption …

Modeling Core Generation And Transport Phenomena Of Microcapsules, Xiaoshuo Wu

Doctoral Dissertations

Microcapsules play an important role in chemical, biomedical, and medical research. Of importance is their potential use as bio-sensors, as microreactors, and for drug delivery. In this dissertation, Computational Fluid Dynamics methodology is used to model the generation of droplets or cores (using alginate and oil) and to determine from the model process parameters needed for generating cores of homogeneous size for the manufacturing of microcapsules. Also, material diffusion through a microcapsule for controlled release is modeled based on finite difference methodology. The model was applied to experimental data on dextran release from microcapsules in order to estimate the diffusion …