Investigation of Lithium Ion Battery Electrodes: Using Mathematical Models Augmented with Data Science to Understand Surface Layer Formation, Mass Transport, Electrochemical Kinetics, and Chemical Phase Change

This thesis first uses physical scale models to investigate solid-state phenomena - surface layer formation, solid-state diffusion of lithium, electrochemical reactions at the solid-electrolyte interface, as well as homogeneous chemical phase change reactions. Evidence is provided that surface layer formation on the magnetite, Fe3O4, electrode can accurately be described mathematically as a nucleation and growth process. To emulate the electrochemical results of the LiV3O8 electrode, a novel method is developed to capture the phase change process; this method describes phase change as a nucleation and growth process. The physical parameters of the LiV3O8 electrode: the solid-state diffusion coefficient, phase change saturation concentration, phase reaction rate constant, and exchange current density, are all quantified and the agreement with experimental results is compelling. Electrochemical evidence, corroborated by results from density functional theory, indicate that delithiation is a more facile process than lithiation in the LiV3O8 electrode. Further investigation of the LiV3O8 electrode is undertaken by coupling the crystal scale model to electrode scale phenomena. Characterization of the LiV3O8 electrode by operando EDXRD experiments provides a unique and independent set of observations that validate the previously estimated physical constants for the phase change saturation concentration and phase change reaction rate constant; they are both found to be consistent with their previous estimates. Finally, it is observed that anodic physical phenomena are important during delithiation of the cathode because the kinetics at the anode become mass-transfer limited. Finally, it is illustrated that coupling physical models to data science and algorithmic computing is an effective method to accelerate model development and quantitatively guide the design of experiments

STAT5 Signaling in Macrophages Regulates Mammary Gland Development and Tumorigenesis

University of Minnesota Ph.D. dissertation. July 2017. Major: Microbiology, Immunology and Cancer Biology. Advisor: Kathryn Schwertfeger. 1 computer file (PDF); x, 196 pages.The studies performed in this dissertation have focused on the role of STAT5 signaling in macrophages during different environmental contexts. We have demonstrated that STAT5 controls macrophage function in the developing mammary gland by regulating aromatase expression and estrogen signaling. Using autochthonous and transplant models of mammary tumorigenesis, we have shown that STAT5 signaling regulates tumor-associated macrophage function by modulating the expression of immunoregulatory and co-stimulatory molecules. Finally, these studies have revealed the ability of a clinically-relevant JAK/STAT inhibitor to induce the expression of pro-tumorigenic factors in macrophages and have demonstrated the need to understand the effects of systemic therapies on other cells in the tumor microenvironment

Modeling hydrodynamic self-propulsion with Stokesian Dynamics. Or teaching Stokesian Dynamics to swim

We develop a general framework for modeling the hydrodynamic self-propulsion (i.e., swimming) of bodies (e.g., microorganisms) at low Reynolds number via Stokesian Dynamics simulations. The swimming body is composed of many spherical particles constrained to form an assembly that deforms via relative motion of its constituent particles. The resistance tensor describing the hydrodynamic interactions among the individual particles maps directly onto that for the assembly. Specifying a particular swimming gait and imposing the condition that the swimming body is force- and torque-free determine the propulsive speed. The body’s translational and rotational velocities computed via this methodology are identical in form to that from the classical theory for the swimming of arbitrary bodies at low Reynolds number. We illustrate the generality of the method through simulations of a wide array of swimming bodies: pushers and pullers, spinners, the Taylor=Purcell swimming toroid, Taylor’s helical swimmer, Purcell’s three-link swimmer, and an amoeba-like body undergoing large-scale deformation. An open source code is a part of the supplementary material and can be used to simulate the swimming of a body with arbitrary geometry and swimming gait

Billions in Misspent EU Agricultural Subsidies Could Support the Sustainable Development Goals

The Common Agricultural Policy (CAP) is the guiding policy for agriculture and the largest single budget item in the European Union (EU). Agriculture is essential to meet the Sustainable Development Goals (SDGs), but the CAP's contribution to do so is uncertain. We analyzed the distribution of (sic)59.4 billion of 2015 CAP payments and show that current CAP spending exacerbates income inequality within agriculture, while little funding supports climate-friendly and biodiverse farming regions. More than (sic)24 billion of 2015 CAP direct payments went to regions where average farm incomes are already above the EU median income. A further (sic)2.5 billion in rural development payments went to primarily urban areas. Effective monitoring indicators are also missing. We recommend redirecting and better monitoring CAP payments toward achieving the environmental, sustainability, and rural development goals stated in the CAP's new objectives, which would support the SDGs, the European Green Deal, and green COVID-19 recovery

Microbial Life in Challenging Environments

Microorganisms are nearly ubiquitous on Earth, but the identity and function of microbial communities are inherently dependent on the properties of the specific environment in question. Here, I have studied soils around the world to answer questions about how the functional attributes of microorganisms allow them to respond to challenging environmental conditions. First, I explore how microbial communities in soils change across environmental gradients in Antarctica. I show that microbes in Antarctic surface soils are most restricted by low temperatures, low water availability, and high concentrations of salt. Microbial communities near the polar plateau, the most challenging environment, are dominated by Actinobacteria and Chloroflexi, and are enriched in genes associated with the oxidation of hydrogen gas as an energy source. Second, I show that the earliest microbial colonizers of a newly-formed volcanic island in the Kingdom of Tonga are chemolithotrophs that appear to have come from nearby geothermal systems. While many of these microbes utilize sulfur as an energy source, the most abundant organisms have genes that indicate they can oxidize trace gases including carbon monoxide and hydrogen. Finally, I show that organisms associated with carbon limited subsurface soils tend to have smaller genomes, grow more slowly, and have more gene pathways associated with metabolism and the storage of carbon. Taken together, these studies shed light on microbial survival in challenging soil environments and show the varied ways in which microbial communities interact with and are affected by their surroundings.</p

A harmonized and spatially explicit dataset from 16 million payments from the European Union's Common Agricultural Policy for 2015

The Common Agricultural Policy (CAP) is the largest budget item in the European Union, but varied data reporting hampers holistic analysis. Here we have assembled the first dataset to our knowledge to report individual CAP payments by standardized CAP funding measures and geolocation. We created this dataset by translating, geolocating to the county or province (NUTS3) level, and consistently harmonizing payment measures for over 16 million payments from 2015, originally reported by EU member states and compiled by the Open Knowledge Foundation Germany. This dataset and code allow in-depth analysis of over V60 billion in public spending by purpose and location for the first time, which enables both individual payment tracing and analysis by aggregation. These data are representative of the distribution of annual CAP payments from 2014 to 2020 and are of interest to researchers, policy makers, non-governmental organizations, and journalists for evaluating the distribution and impacts of CAP spending

Boy Scouts of America Concept Site Master Plan and Improvements

Our team, G1 Engineering, has partnered with the Boy Scouts of America to provide an update to their master plan for the Outdoor Education Center site located at 600 S. 120th Street, Lincoln, NE. Our work included providing transportation solutions; drainage evaluations; investigation of geotechnical conditions; environmental evaluation and determination of permitting requirements; preparation of concept design plans for bridges, drainage, utilities, and overall site plan; and evaluation of structural elements included in the project. Two streams cross the property presenting site access issues. Our team provided pedestrian, UTV, and emergency vehicle access bridges to address these issues. With the two streams on the property, a majority of the land is classified as a floodway or a floodplain. As such, there are regulations placed on any structures built in these areas to not raise flood elevations. Recent expanded use of the facility has led to strains on the parking areas and wastewater facilities. Our team has proposed solutions for expanded parking lots and lagoon operations. Finally, our team investigated the geotechnical conditions present on the site to allow for proper construction and placement of foundations of proposed structures