Master's Theses (Plan A and Professional Engineering Design Projects)

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    Climate Change and Tallgrass Prairies: Exploring the Interaction of Extreme Weather and Invasion in Managed Prairie Systems
    (2020-12) Ratcliffe, Hugh
    Climate change will increasingly shift seasonal timing and increase the frequency and intensity of extreme events like drought and severe wet conditions, all of which threaten to amplify other global change drivers like invasion. Consequently, understanding how conservation management actions like prescribed burning interact with climate is increasingly pressing for invasive management. Although prescribed burning has been widely demonstrated to increase native plant diversity and suppress a number of invasive species, understanding under what current and future conditions burning will be most effective remains an ongoing focus of applied prairie ecology research. Earlier springs and extended growing seasons will shift the timing and availability of resources and niche space, which may disproportionately advantage invasive species and also influence the outcome of burning. Furthermore, northern tallgrass prairies will experience intensified extreme precipitation patterns characterized by more precipitation falling in fewer events interspersed with longer dry periods and amplified evapotranspiration. Because moisture availability functions as a key determinant of prairie composition, theory and evidence suggest drought conditions will hinder invasion, whereas wetter conditions will enhance invasion. Here, I conducted two analyses exploring the effect of weather on prairie invasion dynamics from 2010-2019 in 25 observed prairie sites and 267 transects spread throughout Minnesota, USA. First, I estimated the effects of burning, start time of the growing season, and their interaction. Second, I estimated how an increase in extremely wet or dry months altered invasive abundance and influenced the effectiveness of burning. For the first analysis, I determined that burning reduced both total invasive and invasive cool season grass abundance, and that this reduction persisted over time for invasive cover but quickly waned for frequency. Additionally, I found that growing season start does indeed influence community composition but that later starts rather than earlier increased invasive abundance. For the second analysis, I found that a greater occurrence of abnormally wet months increased invasive abundance and minimal evidence that abnormally dry conditions hinder invasion. Furthermore, I did not observe additive interaction effects of drought and prescribed burning but did find that an increase in the number of wet months reduced the effectiveness of burning. Together, these results suggest that, although earlier spring timing is unlikely to be a primary mechanism driving increased invasion, more frequent extremely wet and dry months may intensify invasive dominance and hinder our ability to suppress invasion species via prescribed burning. Ultimately, I propose that future research should seek to better understand abiotic controls on invasive species’ phenologies, how precipitation seasonality influences invasive performance, and also identify potential thresholds in ecological processes to understand whether responses in community invasion dynamics are abrupt or gradual.
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    Using CRISPR to Model MCT1 Deficiency in Pluripotent Stem Cells.
    (2024) Reutzel, Bryan
    Monocarboxylate transporter 1 (MCT1) plays a key role in transporting monocarboxylates such as lactate, pyruvate, and ketone bodies across the neurovascular unit/blood brain barrier (NVU/BBB). Human MCT1 is a highly conserved 500 amino acid protein embedded in the plasma membrane which contains twelve transmembrane segments with its amino and carboxyl termini in the cytoplasm (Figure). It acts as a facilitative carrier that transports a monocarboxylate and H + in equimolar amounts down a concentration gradient. Some carboxylate drugs may enter the brain via MCT1 and because of its role in metabolism, it has become the target for transport inhibitors (α-cyano-4-hydroxycinnamate, MD-1, AZD3965). Despite the important function of MCT1 in moving metabolically relevant substrates, there have been reports of mutations in the SLC16A1 gene, which codes for MCT1, and render the protein product dysfunctional. Patients with these mutations present with metabolic ketoacidosis that sometimes include seizures, vomiting, and mild to moderate developmental delay. There are currently no in vitro models of MCT1 deficiency in human cells. We hypothesized that creating a cell line of human stem cells in which the SLC16A1 gene is altered would be useful for characterizing the role of MCT1 in the metabolism of cells of the NVU. We therefore used CRISPR/Cas9 editing of human induced pluripotent stem cells (iPSCs). We were able to isolate a heterozygous KO cell line, and were further able to use the isolated line to attempt to create a full/homozygous knockout. The characterization of the resulting cell lines of this study will provide insight into how this pathology may affect the NVU, as well as provide a model system to further investigate this genetic disease.
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    The Potential to Generate Exogenic Interneurons for Alzheimer’s Disease via Blastocyst Complementation
    (2022-12) Johnson, Sether
    Alzheimer’s disease (AD) currently affects millions of patients worldwide, and to date the development of effective therapies has been slow. In AD, numerous types of neural cells become dysfunctional and are susceptible to degeneration, leading to cognitive deficits. One particular cell type affected are GABAergic inhibitory interneurons. Normally, these cells function as modulators of neural circuits, and are associated with maintenance of network synchrony and oscillatory signaling important for memory encoding. Impairments in short term memory, electrophysiological abnormalities such as neural hyperactivity and epileptiform spikes, and loss of interneurons are seen in AD patients and AD mouse models. These observations suggest that degeneration and dysfunction of interneurons contributes to cognitive deficits in AD. Thus, restoring interneuron activity is one potential approach to treat AD. The generation of exogenic interneurons via blastocyst complementation is one promising method to generate these cells. In this method, interspecies chimeras are created by genetic editing in a host blastocyst, which establishes a developmental niche to be filled during expansion of the progeny of donor pluripotent stem cells (PSCs) injected into the blastocyst. Blastocyst complementation has several advantages compared to in-vitro directed differentiation of stem cells, namely that development occurs in an in-vivo context. Thus, progenitor cells are exposed to all the inductive cues needed for differentiation to the appropriate cell phenotype of interest, and therefore may more faithfully recapitulate the intended cell-type specific gene networks and biomolecular characteristics of those cells. Studies have shown that this technique can be applied for CNS tissues including specific brain regions. Specifically, previous work from the Low Lab at the University of Minnesota has shown that targeting the homeobox gene HHEX establishes a niche for the formation of various organs from donor cells including liver, pancreas, and brain (Ruiz-Estevez et al., 2021). HHEX may be a viable target gene for the generation of exogenic interneurons as previous work has indicated that knockout of HHEX impairs development of the medial ganglionic eminence (MGE), a developmental structure enriched in GABAergic interneuron progenitors (Martinez-Barbera et al., 2000). In addition, many studies have demonstrated that engraftment of MGE cells can reduce cognitive and electrophysiological deficits in AD mouse models. This suggests that the transplant of exogenic interneurons may be a feasible strategy to restore interneuron activity and reduce cognitive deficits in AD. While the generation of human-animal brain chimeras is controversial, recent surveys indicate the public is amenable to the concept for research and therapeutic use (Crane et al., 2020). Thus, future translation of this approach using human-porcine chimeras may provide exogenic human interneurons to treat AD patients. This thesis will describe the scientific background and rationale for exogenic interneuron generation by HHEX KO/blastocyst complementation as a potential approach to treat AD. It will also show preliminary analysis of HHEX KO/complemented mice, and show testing of a primary antibody for Lhx6 in wild type mouse tissue prior to the antibody being used to search for donor-derived interneuron progenitors in chimeras.
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    3D Printing Of Large-Scale Integrated Microfluidic Devices
    (2024) Kaarthik, Saravanan Sujit
    The ability to manufacture large-scale integrated microfluidic devices (mLSI) in an automated fashion with high throughput could impact numerous areas, including single-cell assays, drug discovery, and multi-sample analysis of human fluids. Conventional microfluidics fabrication is labor-intensive and requires the use of specialized facilities. Our group previously pioneered a method to 3D print microfluidic channels and valves by extruding silicone filaments in angular stacks. This technique faced limitations in scaling due to slow printing speed (1 mm/s) and inability to generate multiplexed flows. Here, we present an approach to 3D print mLSI devices that introduces an innovative method to reinforce channels locally and reduce the printing time 20-fold by doubling the extrusion diameter of the filaments. This allows for the incorporation of a Boolean design strategy that requires specific valves to remain open when actuated. This work paves the way for point-of-need mLSI production for medical diagnostics and disease detection.
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    Seasonal Prey Resource Partitioning Among Salmonids In The Bois Brule River, Wisconsin
    (2024) McCann, Daniel
    Over the past century, intentional introductions of non-native Salmonids into Lake Superior and its tributaries have raised concern about possible interactions with native Brook Trout (Salvelinus fontinalis), which have historically been subject to local extirpations. The Upper Bois Brule River, Wisconsin currently supports a diverse and abundant assemblage of Salmonid species, including Brook Trout, Brown Trout (Salmo trutta), Rainbow Trout (Oncorhynchus mykiss), Coho Salmon (Oncorhynchus kisutch), and Chinook Salmon (Oncorhynchus tshawyscha). To investigate underlying reasons for apparent co-existence of potentially competing species, I documented the seasonal diet characteristics among coexisting Salmonids and compared stomach content data to seasonal prey abundances (macroinvertebrates) in the benthos and stream drift. The primary objective was to determine if niche partitioning reduces competitive interactions between Brook Trout, Brown Trout, Rainbow Trout, and juvenile Coho Salmon in the Bois Brule River, Wisconsin. Results indicated that Brook Trout and Brown Trout had significant diet overlap during spring, summer, and fall sampling dates, while there were no instances of significant dietary overlap between the non-native species. Several positive relationships between diet overlap and the abundances of different prey categories suggest prey resource partitioning in response to competition may underlie the co-occupation of Salmond species in my study area. All Salmonid species showed positive selection for Trichoptera larvae during spring, summer, and fall. In addition, Brook Trout and Brown Trout showed positive selection for Gastropods during every season. Brook Trout were the only species with strong preferences for Crustaceans, while Rainbow Trout were the only species with preferences for Ephemeroptera nymphs. Brook Trout and Rainbow Trout exhibited opportunistic diets, while Brown Trout tended to feed primarily from the benthos and Coho Salmon fed mainly on surface-oriented prey. It’s likely that the persistence of Brook Trout in the presence of non-native Salmonids is attributed to their flexibility in foraging modes, utilization of increased invertebrate drift rates, and consumption of less preferred prey items. This study provides new information on resource utilization, niche partitioning, and resource overlap among multiple coexisting Salmonid species and may be helpful for future research and management with sympatric populations of native and non-native Salmonid species.
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    Antibiotic Resistant Gene Prevalence In Primary And Secondary Endodontic Infections: A Whole-Metagenome Shotgun Based Study
    (2023-08) Mieczkowski, Shay
    PURPOSE: The purpose of this study was to assess the prevalence of antibiotic resistant genes in primary and secondary endodontic infections using whole-metagenome shotgun sequencing. This study was also used to determine if a difference exists between the counts per million of antibiotic resistant genes present in primary versus secondary endodontic infections. MATERIALS AND METHODS: Twenty-five samples from patients with primary root canal infections, and twenty samples obtained from previously treated teeth currently diagnosed with apical periodontitis were analyzed with whole-metagenome shotgun sequencing at a depth of 15–20 M reads. Taxonomic and functional gene annotations were made using MetaPhlAn3 and HUMAnN3 software. We profiled a manually curated list of antibiotic resistant genes in our metagenomic data using the KEGG BRITE database (https://www.genome.jp/brite/ko01504). To assess if a significant difference exists between infections belonging to primary and secondary endodontic infections, a Mann-Whitney U test non-parametric test was used. P-value was two tailed and significance was determined at P<0.05. RESULTS: Thirty-seven total samples yielded high-quality DNA, 21 and 16 samples that belonged to primary and secondary infection samples, respectively. The most prevalent antibiotic resistant genes present included the metallo-beta-lactamase family protein, MFS transporter (DHA1 family, bicyclomycin/chloramphenicol), multidrug resistance protein (MATE family), membrane fusion protein (multidrug efflux system), and multiple antibiotic resistance protein. The bacteria encoding for antibiotic resistant genes that have the highest prevalence in primary and secondary endodontic infections included Eubacterium infirmum, Tannerella forsythia, Psuedopropionibacterium propionicum, Dialister pneumosintes, Prevotella Denticola, and Selenomonas sputigena. Mann-Whitney U analysis showed no significant difference between counts per million of primary and secondary endodontic infections (P = 0.6532). CONCLUSIONS: Numerous antibiotic resistant genes are prevalent and encoded for in both primary and secondary endodontic infections. No significant difference was found between the prevalence in counts per million of antibiotic resistant genes between the microbial composition in cases with primary or secondary endodontic infections.
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    Estimating Observer Detection Probability and Flushing Probability of Upland Nesting Ducks
    (2024-01) VeltKamp, Hunter
    Researchers commonly use vehicle-towed nest drags to locate duck nests in upland habitats, but the efficiency of this method has rarely been assessed. During a two-year study of duck nest survival in northeastern North Dakota, we assessed several potential sources of detection failure while using ATV-towed chain or cable-chain drags for nest searching. Our standard protocol involved teams of 2 ATV operators with no dedicated observer, therefore search-team members had to divide their attention between looking backwards to monitor the drag and looking forward to navigate, so some flushes may have gone undetected because both observers were looking away. We employed independent double-observer methodology to estimate the detection probability for each observer, and considered a variety of variables that might influence detection probabilities. We found that detection probability varied substantially among observers, ranging from 0.751 to 0.949, and that detection probability peaked in the middle of the 2020 nesting season and started out higher in 2021 with a gradual increase throughout the season. Although individual observers often failed to detect flushing females, we estimated that both observers working together detected 1957 out of 1993 (98.1%, SE = 0.2%) available flushing events. Based on our findings, we see no practical need to employ a third crew member as spotter because very few duck nests were missed due to failure to observe flushing hens. Another source of detection failure includes nesting females that failed to flush from the nest drag. To measure flushing probability, we used a 2-pass removal estimator based on repeated searches conducted ~ 10 minutes apart at 45 nesting fields during 2020 and 2021. The leading crew found 761 nests and the trailing crew found 141 nests. Estimated flushing probability was 0.707 (95% CRI 0.636 - 0.770) per search event. Variation between species was apparent with blue-winged teal having the lowest flushing probability at 0.62 and gadwall having the highest at 0.85. This means that the apparent composition of the nesting population based on nests found is not the same as the actual composition, with gadwall being overrepresented and blue-winged teal being underrepresented, relative to other species. Flushing probability also varied among study sites ranging from 0.52 to 0.87. There was little evidence that flushing probability differed by year, search date, or between cable-chain vs. chain only nest drags. In order to consider additional sources of variation, future studies should collect additional data for any variable that could have the possibility of causing a hen to sit tight and not flush. Focusing on increasing the flushing probability is more beneficial to increasing the number of found nests than increasing observer detection probability.
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    Characterization and Modification of Scaled-Up Pea and Chickpea Protein Isolates Extracted using Salt Solubilization Coupled with Membrane Filtration in Comparison to Commercial Proteins
    (2023-12) Yaputri, Brigitta
    The demand for plant protein ingredients continues to grow, along with growing interest in plant-based products, such as meat analogues. Soy protein is the most common plant protein source in the market due to availability, low cost, excellent nutritional quality, and good functional properties. In the meat analogue sector, soy protein is commonly combined with wheat gluten to form a meat-like fibrous texture via high moisture extrusion. However, soy protein and gluten are among the “Big Nine” allergens in the U.S., in addition to soy being a genetically modified (GMO) crop, which raises concerns and skepticism among consumers, creating demand for alternative plant protein sources. Among legume crops, pea and chickpea have been known to be good sources of protein. Pea protein is a major protein source that has been used in many food and beverage applications. Chickpea protein is a rather emerging protein source and is less studied compared to pea protein. There remains a limited availability of commercial chickpea protein ingredients in the market. As legumes, pea, chickpea, and soy share similar protein profile and structure, indicating the potential for pea and chickpea protein to substitute soy protein. However, pea and chickpea proteins have inferior functionality compared to soy protein, particularly gel strength. Protein functionality not only depends on the inherent protein structure and amino acid compositions but also on external factors, such as extraction methods. Currently, alkaline extraction coupled with isoelectric precipitation (AE-IEP) is the most common extraction method used in the industry to produce plant protein isolates. Extreme alkaline conditions may cause damage to the protein’s native structure due to excessive denaturation, which can impair protein functionality. Therefore, to compete with soy protein, there is a need to explore and optimize a milder extraction process to produce functional pea and chickpea protein isolates (PPI and ChPI). One method that is gaining traction is salt solubilization coupled with membrane filtration, which has mostly been performed at lab-scale to produce soy and pea protein isolates. To conduct a comprehensive evaluation, the industrial feasibility of such extraction process, following lab-scale optimization for ChPI, and its impact on the protein’s structure and function, must be determined. In addition to the extraction method, structural modification can also be used to further enhance targeted protein functionality. For meat analogue applications, good protein network, demonstrated by high gel strength, is important for the formation of meat-like fibrous texture. Enzyme transglutaminase (TG) has been used in the food industry to catalyze the formation of inter and intra-molecular crosslinks between the amino acids lysine and glutamine. Pea and chickpea are high in lysine, making them suitable substrates for TG. As research on this topic is limited, the selection of treatment parameters, along with protein structural and functional characterization, need to be done to determine the impact of TG on pea and chickpea protein. Therefore, the objectives of this study were: (1) to investigate the feasibility of scaling-up salt extraction coupled with membrane filtration and its impact on the structure and function of chickpea protein in comparison to pea protein and (2) to investigate the impact of transglutaminase treatment on the structure and function of pea and chickpea proteins. For objective 1, the salt solubilization conditions, including salt concentration and temperature were optimized for ChPI on benchtop based on protein purity and yield. Optimized benchtop extraction was then scaled-up at pilot scale to evaluate the scalability based on purity and yield of the chickpea protein. For comparison purposes, scaled-up (SU) PPI was produced following the same extraction method, according to our previous study. Structural characteristics of the SU PPI and SU ChPI were compared to benchtop and commercial isolates by determining the protein profile via SDS-PAGE, protein denaturation via differential scanning colorimetry (DSC), surface charge via zeta potential, and surface hydrophobicity by a spectrophotometric method. Functional characteristics of the SU isolates in comparison to benchtop and commercial counterparts, which included solubility, gel strength, water holding capacity, and emulsification properties, were also assessed. For objective 2, SU isolates were further treated with TG to induce polymerization. Different treatment conditions, including enzyme concentration and treatment time were tested and selected based on degree of polymerization, protein denaturation, and gel strength, as determined by SDS-PAGE, DSC, and thermal-induced gelation. The structural characteristics of the modified isolates (TG PPI and TG ChPI) were determined by evaluating the protein profile via SDS-PAGE, protein molecular weight distribution via SE-HPLC, protein denaturation by DSC, secondary structure via FTIR, surface charge via zeta potential, and surface hydrophobicity by spectrophotometric method in comparison to SU isolates and commercial ingredients. The functional properties of TG PPI and TG ChPI were determined by evaluating the protein’s solubility, gel strength, and emulsion capacity. The optimum salt solubilization conditions for ChPI were 0.5 M NaCl at room temperature, similar to those used for PPI, followed by ultrafiltration and dialysis. The benchtop and SU isolates had comparable protein purity with >90% protein and low ash content. The production of SU ChPI resulted in lower yield (41%) compared to benchtop production (52%), which was also observed for SU PPI, due to unavoidable losses during large scale production. The SU and benchtop isolates shared a similar protein profile. However, SU isolates experienced partial protein denaturation, higher surface hydrophobicity, and some polymerization due to thermal treatments during pasteurization, evaporation, and spray drying. Changes in structural characteristics of the SU isolates significantly impacted their functionality, including superior gel strength compared to their benchtop counterparts. Compared to the commercial pea and chickpea proteins, SU isolates were less denatured and polymerized, confirming that the adopted SE-UF process is milder compared to commercial isolation processes. Further, TG treatment of SU isolates resulted in a high degree of polymerization and a significant increase of intermolecular β-sheet. Heat treatment during enzyme incubation and inactivation step resulted in complete protein denaturation. TG-modified isolates had significantly lower solubility compared to their SU counterparts due to the formation of insoluble high molecular weight (MW) polymers and relatively high surface hydrophobicity. In contrast, TG isolates showed significantly stronger gel strength compared to the SU isolates, which was attributed to TG-induced polymerization. On the other hand, TG ChPI had significantly lower EC compared to SU ChPI, whereas that of TG PPI was not impacted, which was attributed to differences in legumin to vicilin ratio between pea and chickpea proteins. This study, for the first time, successfully demonstrated the scalability of chickpea protein isolate production following a mild SE-UF process. SU extraction resulted in protein isolates with high protein purity and good yield and preserved the protein’s structural integrity in comparison to the commercially produced ingredients, leading to better functionality. In addition, this study uniquely demonstrated the holistic impact of TG on the structure and function of SU PPI and SU ChPI, which could be leveraged to enhance texturization potential for meat analogues applications.
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    Insights into Biomechanics of Pelvic Organs: A 3D Finite Element Analysis Investigating Vaginal Vault Prolapse Mechanisms and Surgical Intervention
    (2024-01) Togaru, Lavanith
    Pelvic Floor Disorders (PFDs), including Vaginal Vault Prolapse (VVP), pose significant health concerns for women, affecting urinary, rectal, and sexual functions. This study addresses the lack of understanding in prolapse mechanisms and pelvic organ dynamics through a precise 3D Finite Element Analysis (FEA) model. Developed with data from the visible human project, this model integrates diverse material properties, ensuring accurate representation of pelvic organ behavior. Investigating nine simulated cases, the study unveils subtle variations in pelvic dynamics, emphasizing the link between changes in pelvic organ stiffness and prolapse. A simulated surgical Y-mesh demonstrates efficacy in rectifying VVP and pelvic floor issues. This research contributes substantially to VVP biomechanics, emphasizing the integral nature of pelvic organ interactions and urging further exploration of long-term surgical effects. The model not only enriches discussions on women's health but also lays the groundwork for advanced models to understand and manage Vaginal Vault Prolapse
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    Gut Microbial Metabolite, Sodium Butyrate Regulates The Blood-Brain Barrier Transport And Intra-Endothelial Accumulation Of Alzheimer’S Disease Amyloid-Beta Peptides
    (2024-01) Veerareddy, Vaishnavi
    Alzheimer's disease (AD) is a common type of dementia observed in the elderly with brain amyloid beta (Aꞵ) deposits as one of its pathological hallmarks. Risk factors contributing to AD include age, genetics, inflammation, gut dysbiosis, and co-morbidities like diabetes, hypertension, and insulin resistance1. Recent studies have highlighted the necessity of investigating the combined effect of risk factors on AD onset and progression2. In addition, a majority of AD patients are diagnosed with cerebrovascular dysfunction, which is considered to be a significant contributor to the disease progression3. Moreover, the gut microbiome diversity was shown to be diminished in AD patients4. One of the interactions between the gut and the brain is mediated by gut microbial metabolites through the gut-brain axis5. Gut microbial metabolites include mainly short-chain fatty acids (acetate, propionate, butyrate) and trimethylamine N-oxide (TMAO)6. Particularly, butyrate treatment was shown to improve impaired cognition and reduce Aꞵ deposition in the AD brain, although the underlying mechanisms are yet to be characterized7. Previously, we reported the impact of insulin signaling on Aꞵ trafficking between the brain and the blood via the blood-brain barrier (BBB), which lines the cerebrovascular lumen and regulates Aꞵ levels in the brain8. However, the effect of gut microbiome metabolites on Aꞵ trafficking/accumulation at the BBB and endothelial insulin signaling remains unknown. In this study, we investigated the effect of one of the bacterial metabolites, sodium butyrate (NaBu), on Aꞵ accumulation at the BBB endothelium and the role of endothelial insulin signaling. The NaBu decreased Aꞵ40 with 6 h treatment and Aꞵ42 accumulation upon 2 h and 6 h treatments in BBB cell (hCMEC/D3) monolayers in vitro. Moreover, NaBu increased the phosphorylation of protein kinase B (PKB/AKT) and extracellular signal-regulated kinase (ERK) upon 6 h treatment. Inhibitor studies were conducted to evaluate if NaBu effect on Aꞵ accumulation at the BBB is regulated by insulin signaling. Treatment with AKT inhibitor (MK2206) and NaBu increased Aꞵ42 accumulation compared to the NaBu alone treated group. Similarly, treatment with MEK inhibitor (trametinib) and NaBu increased Aꞵ42 accumulation compared to the NaBu-treated group. These findings suggest the involvement of AKT and ERK pathways in NaBu-mediated changes in Aꞵ42 accumulation at the BBB. Also, NaBu affects the expression of transporters and receptors at the BBB. The NaBu treatment increased permeability glycoprotein (P-gp) and decreased receptors for advanced glycated end products (RAGE) compared to the Aꞵ treated group. Further, studies need to be conducted to elucidate mechanisms underlying NaBu effect on the BBB endothelium in AD. Keywords: Alzheimer’s, Aβ, Blood-brain barrier, dysbiosis, sodium butyrate, Insulin signaling, P-gp, RAGE.
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    Pea Protein Globulins: Does their Relative Ratio Matter?
    (2023-07) Husband, Holly
    The relatively low abundance of 11S legumin in pea protein, coupled with the wide diversity in 7S vicilin to 11S legumin ratio among pea protein ingredients, are assumed contributors to pea protein’s inferior and inconsistent functionality and nutritional quality relative to soy protein. To improve the performance of pea protein ingredients in food and beverage applications, optimum protein profile must be identified. Therefore, this work followed a holistic approach to determine the impact of 7S/11S ratio on pea protein structure, functionality, and nutritional quality. Vicilin- and legumin-rich fractions were isolated and combined in different proportions to produce pea protein samples of varying 7S/11S ratios. For the first time, pea protein isolate was also enriched with 11S legumin to evaluate the impact of 11S abundance on functionality within an unfractionated protein matrix. Results revealed the isolated 7S vicilin had 6 fold higher gel strength and 5 fold higher emulsification capacity, but significantly lower nutritional quality, than the isolated 11S legumin. Despite having significantly higher sulfur-containing amino acids, high protein polymerization in the isolated 11S legumin contributed to the relatively low functionality. Further, fractionation induced unique changes to amino acid composition, resulting in significantly lower amino acid scores for isolated 7S vicilin and 11S legumin relative to pea protein isolate. Accordingly, 11S legumin enrichment of pea protein isolate did not improve functionality or nutritional quality. Nevertheless, this work contributed foundational knowledge that will provide direction for future studies aiming at devising strategies to improve the quality and consistency of pea protein ingredients.
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    Exploring the Role of the Cell Membrane in Formaldehyde Stress Tolerance in Methylorubrum extorquens
    (2024-01) Singla, Deepanshu
    Methanol is a promising alternative to sugars as a feedstock for bacteria in biomanufacturing as it does not compete with food demands and can be sustainably produced from greenhouse gases. Methylorubrum extorquens is a methylotroph that naturally uses reduced single-carbon compounds, such as methanol, as a sole source of carbon and energy. Understanding the metabolic regulation and physiology of M. extorquens will enable the adoption of methanol in the fermentation industry. Methanol utilization flows through formaldehyde, a toxic intermediate, which is generated in the periplasm and then moves into the cytoplasm to be further metabolized. However, the regulation of formaldehyde movement across inner cell membrane has not been studied in M. extorquens. Formaldehyde can damage proteins and DNA by forming diverse crosslinks or diffuse into lipid membranes and react with unsaturated bonds, damaging lipids and potentially disrupting the membrane. As most fatty acids in M. extorquens lipidome are unsaturated, we suspect they are prone to damage and that M. extorquens must have strategies for mitigating this damage. Here we show that cells acclimated to exogenous or endogenous formaldehyde have reduced membrane permeability and an altered lipid profile. We hypothesize that reduced membrane permeability limits the formaldehyde diffusion through membrane, regulating formaldehyde flux and preventing contact with unsaturated fatty acids which may make the membranes more resistant to formaldehyde mediated damage.
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    Textile Mechanical Recycling: Design, Improvement, and Analysis of a Carding Wire Drum System
    (2023-12) Teixeira Franca Alves, Paulo Henrique
    Textile manufacturing is responsible for significant environmental impacts such as 35% of primary microplastics production, 20% of global clean water pollution, and 10% of global greenhouse gas emissions. The growing problem of textile waste, further fueled by fast fashion and overconsumption, is set to grow with the rising global population. In 2018, 17 million tons of textile waste was generated in the US of which only 15% was recycled. Furthermore, only 1% of recycling policy research focuses on textile waste, demonstrating the great need for new studies and technologies to mitigate this problem. Additionally, present textile recycling technologies produce downcycled fibers, have high costs, or lack scalability for industrial production volumes. Despite the existence of various shredding machines for recycling textiles, the parameters that can influence this process have not been broadly investigated, decelerating the development of machines that could make fiber-to-fiber recycling a possibility. This study investigates the principles behind carded (toothed) drum textile shredding, to optimize the shredding process to obtain reusable fiber while decreasing the generation of fabric pieces and dust. The mechanics involved in subjecting fabrics to tensile and shear forces in a carding wire drum-operated system were investigated to understand better how the textile material behaves during the shredding process. By focusing on the interaction between the feeding and shredding drums and characterizing the failure mechanics of the drum-textile and tooth-yarn interactions, it was proposed that reducing tooth size and increasing the relative speed between drums will enhance the shear failure ratio, increasing the output of fibers and yarns. Because most existing textile recycling technologies are expensive, yield low-quality outputs, or lack scalability for industrial use, there is an urgent need for adaptable and sustainable textile recycling system designs that account for the dynamic nature of the textile and fashion industry. To ensure sustainability, these designs must be flexible enough to adapt to technological advancements, user needs, societal changes, and environmental conditions. To make this possible, flexible and sustainable principles were evaluated and overlapping principles were combined while missing principles were added, creating the design for sustainability and flexibility method (DfSFlex). The Fiber Shredder, a textile mechanical recycling machine, was developed with a focus on flexibility and sustainability and was evaluated based on how well it addressed the DfSFlex principles. The design and assembly processes of this machine were detailed to illustrate the decision-making involved in developing the technology. Later, a performance evaluation of the Fiber Shredder was performed and indicated that increased speed and processing time led to a higher generation of desired outputs (fibers and yarns) reflecting the principles of Design for Separation and Facilitate Resource Recovery in both design and processing. Furthermore, tests involving different materials and fabric structures demonstrated that material type, fabric thickness, and structure significantly influenced the output of recycled fibers. The Fiber Shredder outperformed an industrial shredding machine by producing outputs with fewer undesirable fabric pieces, more desirable fibers and yarns, and lower process losses. However, while effective for laboratory research purposes, the Fiber Shredder has limited capacity and requires automation and scaling up to meet industrial demands. Nonetheless, the development of this technology utilizing sustainable and flexible design principles shows promise in mechanical fiber-to-fiber recycling, contributing to the repurposing of textiles and reducing the amount of textile waste ending up in landfills.
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    Closing the Divide: Exploring Meaningful Technology Use in the Technology Integration Matrix
    (2024) Seylar, John
    The purpose of this mixed-methods study is to investigate the suitability of Technology Integration Matrix Observations (TIM-O) extensity scores to serve as a quantitative proxy for meaningful technology use in K-12 public school settings across the United States. To do so, correlations between TIM-O extensity scores and various school-level socioeconomic indicators were explored using a Cumulative Link Mixed Model. Questions and observations gathered during the model-building process were then used to inform the development of an interview protocol, which was used to gather the experiences and perspectives of three middle school instructional coaches. My analysis uncovered evidence that TIM-O extensity scores could serve as a useful proxy for meaningful technology use, though improvements and further study will be necessary.
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    The role of astrocytic adenosine monophosphate-activated protein kinase in cocaine-related behaviors
    (2022-01) Buczek, Laura
    Cocaine use induces changes in the brain’s structure and function inducing long-lasting changes in behavior and cognition. There are no FDA approved treatments for cocaine use disorder. Investigating cocaine-induced neuroadaptations, specifically changes in brain protein expression and function, will inform molecular targets for future therapeutic drug development. Two proteins, glial glutamate transporter 1 (GLT-1) and phosphorylated adenosine monophosphate-activated protein kinase (pAMPK) are downregulated upon cocaine exposure. It is unknown whether AMPK, expressed in neurons and astrocytes, regulates GLT-1 in the striatum in a cell-specific manner. I will first determine how astrocyte-specific manipulation of striatal AMPK impacts GLT-1 expression and function in the striatum. I will then determine whether the same astrocytic AMPK manipulations influence cocaine locomotor sensitization and acquisition of cocaine self-administration.
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    Immediate Deflection Calculations Of Transition And Cracked Prestressed Concrete Sections
    (2024-03) Wagner, Rachel
    Prestressed concrete is commonly used in floor, roof, and bridge members. In prestressed concrete, the steel strands are tensioned/pulled and then concrete is cast around the strands in the form. Once the concrete has set, the strands are cut, and the member is put into compression from the pre-tensioned strands. Concrete is classified as uncracked, transition, and cracked based on the stress in a critical section (ACI, 2019). In practice, the member is designed to remain uncracked during its service life. When this is not possible, the code requires additional calculations that can increase the complexity of the design, one of these being deflection calculations. Transition and cracked section deflection calculations utilize an effective or cracked moment of inertia that adjusts the stiffness according to the relationship between the applied moment and cracking moment ratio. Though these methods are commonly used, current equations and models are unable to estimate the immediate deflections of transition and cracked prestressed concrete sections in flexure reliably and accurately. The goal of this research is to determine if a solution with current methods exists for transition and cracked sections used in practice, particularly double-tee members. A sample of rectangular and double tees (n = 26) with prestressed reinforcement ratios varying from 0.06% to 0.45% was selected. Each specimen was modeled with five different equations to predict the deflection and loaded incrementally, to provide a plot of applied moment to deflection, and loads at specific stress limits and service moments. As the section progressively cracks under increasing loads, the neutral axis gets smaller as the cracks propagate towards the compressive face. This reduces the available area in the section to provide stiffness and resist the loads. Without calculating the cracked section properties, the reinforcement ratio is used to predict the cracked moment of inertia. The methods consider different ways to account for the changes in the member as it cracked, when to begin softening of the member, and alternative moments to shift the behavior closer to the experimental data. Some limitations to this study include a lack of full-scale double tee deflection specimens and specimens with low reinforcement ratios tested to failure. The methods considered in this study did not provide any greater performance than those already in use. As expected, there was general agreement between the estimated and tested data during the uncracked phase. But as the specimens were further stressed with loading past the cracking moment, the results became less consistent between methods. The equations that had the best results were the PCI and Auburn methods. These methods trended conservatively in their predictions and were computationally straightforward. The other alternative methods diverged from the experimental results as the stress in the member increased, making them a poorer choice for deflection prediction in cracked sections. Due to the overall lack of confidence in the deflection methods for transition and cracked sections, the recommended method continues to be the PCI for its simplicity in computation and performance in this group of test specimens. The Auburn method shows promise and can be revisited with the inclusion of additional data from deflections in full sized specimens.
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    Real Time Angle Of Attack Estimation For The Hycube Flight Vehicle In Gps-Denied Re-Entry
    (2024-01) Vedvik, Sophia
    With global interests in the study of hypersonic flow, large research efforts have gone towards collecting statistically significant amounts of high speed flow data at low costs. CubeSats are proving to be an economical testing platform for a variety of scientific experiments, where valuable hypersonic data can be collected and relayed upon re-entry to Earth. However, due to the budget, volume, and power constraints of CubeSats, many of the on-board sensors, including inertial measurement units (IMUS), have decreased accuracy. For purposeful data collection to occur, the sensors on-board typically work in conjunction with robust synthetic air data algorithms. To back out useful data on the vehicle's response during re-entry, the angle of attack of the vehicle must be estimated with one of such algorithms. This work proposes using an Extended Kalman Filter (EKF) which fuses an attitude determination algorithm with low-grade IMU angular rates and measurements of Earth's magnetic field. But in the case of re-entry, the vehicle will become deprived of Global Positioning System (GPS) data, which is required to obtain estimates of the Earth's magnetic field that work in conjunction with magnetometer magnetic field measurements. Thus, after developing the EKF framework, this work will perform a trade study to analyze ways in which Earth's magnetic field can still be a viable method to aid low-grade IMU attitude estimates. The trade study environment is modeled after the Hypersonic Configurable Unit Ballistic Experiment (HyCUBE), a project in development at the University of Minnesota that is leveraging the CubeSat form factors to collect valuable hypersonic flow data upon re-entry. Future work and improvements to the EKF, as well as the impact of this work will then be discussed.
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    Comparison Of Vickers Hardness Between Dental Ceramics And Hybrid Materials
    (2024-05) Rameh, Stephanie
    The study aims to compare Vickers hardness of five definitive crown materials in a controlled laboratory setting. Materials & Methods: Five specimens (15 x 12 x 1.5 mm) were obtained from each tested material: zirconia (Lava Ultimate), lithium disilicate (IPS e.max CAD), lithium silicate reinforced with zirconia (Celtra Duo CAD), dual polymer hybrid ceramic (Vita Enamic) and resin ceramic hybrid (VarseoSmile Crown Plus). Vickers indenter (Wilson VH3100, Buehler) was used to create 6 pyramid-shaped indentations on each specimen and surface hardness was then measured. Results: A statistically significant difference in Vickers Hardness was found between all tested materials. Zirconia has the highest Vickers hardness while VarseoSmile BEGO has the lowest. Celtra Duo has a higher mean microhardness than Emax, yet still lower than Zirconia. Vita Enamic had lower microhardness than both Emax and Zirconia. VarseoSmile BEGO has lower microhardness than both Emax and Zirconia. Conclusion: Vickers Hardness for the tested materials can be classified as follows: Zirconia > Celtra Duo > Emax > Vita Enamic > Varseosmile BEGO.
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    Professional Sport Corporate Social Responsibility And Opinion Leaders: An Exploration Into The Csr Communication Between Professional Sport Teams And The Media, Regulatory Bodies, And Monitoring Groups
    (2024) Hlina, Matthew
    Critiques of professional sport corporate social responsibility (CSR) often derive from opinion leader stakeholders, which consists of the media, regulatory bodies, and monitoring groups. Yet, little research has gone towards exploring the communicative practices used by professional sport teams to communicate with their opinion leader stakeholders about the CSR activities of their organization. The purpose of this study was to understand the CSR communication strategies that professional sport teams use to demonstrate their legitimacy to their opinion leader stakeholders and to identify the determinants of such communication strategies. The CSR communication strategies identified by Morsing & Schultz (2006) was used as a theoretical framework for this research. A narrative inquiry research design was used to examine the communication between professional sport teams and their opinion leaders. Using semi- structured interviews, data was collected from three professional sport CSR practitioners that were employed by three separate professional sport teams operating in three different North American professional sport leagues. Drawing from narrative thematic analysis, findings showed that professional sport teams used five CSR communication strategies to communicate with their opinion leaders and that seven determinants of CSR communication with opinion leader stakeholders exist. The findings a) extend the theory of CSR communication by providing empirical evidence for novel CSR communication strategies, b) establish a foundation by which to understand professional sport CSR communication with opinion leader stakeholders, and c) provide a framework for practitioners to evaluate and adjust their CSR communication with their stakeholders.