MS, Kent State University, 2019, College of Arts and Sciences / Department of Earth Sciences

Manganese (Mn), an essential nutrient critical for photosynthesis in plants but a toxic element in excess, impacts the fate and transport of other nutrients and toxins, forest metabolism, carbon storage, and ecosystem productivity. Given the significant role Mn can play in ecosystems, it is important to understand how soil geochemistry controls Mn uptake by vegetation. The purpose of this research was to explore how Mn uptake by plants is related to Mn supply to plants through mineral dissolution. We conducted a greenhouse pot experiment to quantify Mn uptake by plants based on controlled geochemical constraints. Specifically, we investigated whether Mn uptake was limited by the supply of Mn to soil solution or by biological controls within the plants. Greenhouse soil pots (quartz sand + peat) that were non-vegetated or vegetated with red maple saplings were supplied with either no added Mn, dissolved Mn, Mn oxides, or crushed shale containing Mn-bearing pyrite. We analyzed the chemical composition of plant tissue to quantify Mn uptake and soil leachate to quantify Mn losses. From these values, we constructed a mass balance model and calculated pseudo-first order rate constants to compare Mn mobilization between treatments. Mn uptake was higher in systems with dissolved Mn because it was not limited by mineral weathering. Mn uptake was also higher in systems supplied with fast-weathering substrates (pyrite in the shale) than slow-weathering substrates (Mn oxides). There were not significant differences in Mn leaching and total Mn loss between vegetated and non-vegetated pots in the Mn-oxide or shale treatments. We conclude that Mn uptake is controlled by dissolution rates of Mn-minerals in soil.

Committee: Elizabeth Herndon (Advisor); David Singer (Committee Member); Chris Blackwood (Committee Member) Subjects: Biogeochemistry; Environmental Geology; Environmental Science; Environmental Studies; Geobiology; Geochemistry; Geology

Doctor of Philosophy, Case Western Reserve University, 2021, Civil Engineering

Permanganate (MnO4-) plays an important role in water treatment as a strong oxidant. Two additives, i.e., bisulfite (HSO3-) and ligands, have been found to significantly accelerate its oxidation rates toward organic contaminants, but the specific mechanisms remain largely unknown or controversial. Reaction rate constants of contaminants toward various oxidants or reductants are an important parameter for optimizing water/wastewater treatment; however, experimentally measuring rate constants for thousands of contaminants is time-consuming and labor-intensive. In comparison, developing quantitative structure activity relationship (QSAR) models for estimating their rate constants is an efficient approach with satisfactory accuracy. The presence of bisulfite can make the oxidation of organic compounds by MnO4- complete in milliseconds. Previous studies concluded that uncomplexed Mn(III) was responsible for this millisecond reactivity. However, we revealed that this ultrafast reactivity was only observed in the presence of O2. We also found that HSO3- and O2 were rapidly consumed when mixing HSO3- with MnO4- in the presence of O2. This was because reactive Mn intermediates, mainly Mn(III) species, were generated in situ from the reaction of HSO3- and MnO4-, which then acted as a catalyst for the reaction of HSO3- and O2. In the presence of organic compounds, this catalytic effect was weakened because the reactive Mn intermediates were consumed by reacting with the organic compounds. However, without O2 these reactive Mn intermediates cannot oxidize the organic compounds. Hence, we concluded that only the Mn(III) with this catalytic role can oxidize organic compounds in milliseconds. This work unveiled the important role of O2 in the HSO3-/MnO4- system, which is important for its real applications. Ligands, such as pyrophosphate (PP), nitrilotriacetate (NTA), and ethylenediaminetetraacetic acid (EDTA), are known to increase the oxidation reactivity of phenolic comp (open full item for complete abstract)

Committee: Huichun Zhang (Committee Chair); Xiong Yu (Committee Member); Daniel Lacks (Committee Member); Anna Samia (Committee Member) Subjects: Environmental Engineering; Environmental Science

Doctor of Philosophy (PhD), Ohio University, 2016, Physics and Astronomy (Arts and Sciences)

The behavior of ferromagnetic alloys of manganese and iron with gallium when coupled with different magnetic and/or non-magnetic systems is investigated. The studies explore how the structural and electronic/magnetic properties vary with thickness and composition, probing systems in the sub-monolayer, ultra-thin, and thin film regimes. Molecular beam epitaxy is used to prepare clean sample surfaces that are subsequently investigated in-situ down to atomic level using scanning tunneling microscopy and Auger electron spectroscopy. A variety of ex-situ methods are also utilized to obtain information about the overall system properties, with additional theoretical calculations accompanying the experimental findings for two of the investigated systems. The first study refers to L10-structured ferromagnetic MnGa(111) ultra-thin films grown on semiconducting GaN(0001) substrates under lightly Mn-rich conditions. Room temperature scanning tunneling microscopy investigations reveal smooth and reconstructed terraces, with the surface structure consisting primarily of a hexagonal-like 2 x 2 reconstruction. Theoretical calculations are carried out using density functional theory, revealing that a Mn-rich 2 x 2 surface structure gives the best agreement with the observed experimental images and Auger electron spectroscopy surface composition investigations. It is found that under such growth conditions, the Mn atoms incorporate at different rates: surfaces become highly Mn-rich, while the bulk remains stoichiometric, making the MnGa system very sensitive to the ratio of elements in its structure. Such behavior reveals a potential recipe for tuning, for example, magnetic properties by carefully controlling the surface reconstruction during growth. With the aim of understanding how the properties change as the growth conditions are varied, we also investigate the structure, surface, and magnetism of ferromagnetic Ga-rich MnGa thin and ultra-thin films grown again on GaN(00 (open full item for complete abstract)

Committee: Arthur Smith (Advisor) Subjects: Condensed Matter Physics; Physics

Master of Science in Engineering (MSEgr), Wright State University, 2011, Materials Science and Engineering

Improvements of the anode performances in Li-ions batteries are in demand to satisfy applications in transportation. In comparison with graphitic carbons, transition metal oxides as well as graphene can store over twice amount of lithium per gram. Recently, graphene-based anodes for Li-ion batteries are under extensive development. In this research, lithium storage characteristics in graphene oxide (GO), GO/Manganese acetate (GO/MnAc), GO/manganese oxide (GO/MnOx) composites and Nano Graphene Platelets (NGP) were studied. The prepared GO delivered reversible capacities of 706mAh/g with an average columbic efficiency of 87%. Reversible capacities of 533 mAh/g were observed for GO/MnAc composite. GO/MnOx nanocomposite thermal annealed at 400°C in inert atmosphere exhibited high reversible charge capacity of 798 mAh/g with an average columbic efficiency of 95% and capacity fade per cycle of 1.8%. The EIS spectra of discharge and charge profiles of GO and GO/MnOx composites were analyzed to investigate the kinetics evolution of electrode process at different stages of lithium storage.

Committee: Hong Huang PhD (Advisor); Daniel Young PhD (Committee Member); Chu Kuan-lun PhD (Committee Member); George Huang PhD (Other) Subjects: Alternative Energy; Automotive Materials; Chemistry; Energy; Engineering; Materials Science; Metallurgy; Nanotechnology

MS, University of Cincinnati, 2008, Medicine : Epidemiology (Environmental Health)

Relation between Dietary Manganese Intake and Biological Markers of Manganese ExposureAbstract Manganese is an essential trace element, yet can be toxic in excess. The inter- and intra- individual variations in manganese levels in different biological media make research difficult. This study examined the relationship between dietary Mn intake and blood Mn. Methods: Subjects were recruited through the Cincinnati Lead study cohort. The Youth/Adolescent Questionnaire was used to evaluate the dietary intake of manganese. Results: The mean manganese dietary intake was 3.25 mg±2.06 (SD). The mean blood manganese concentration was 0.8mg/dl±0.36 (SD). The Spearman rank correlation coefficient between dietary manganese intake and blood manganese was not significant (P value= 0.99). Conclusions: We found no correlation between dietary manganese intake and blood manganese. This is due to our small sample size and the use of the YAQ that has not been designed specifically to measure manganese. More studies are needed to better understand the effect of dietary manganese intake on blood manganese.

Committee: Erin Haynes Dr.P.H (Committee Chair); Paul Succop Ph.D (Committee Member); Tianying Wu M.D,Ph.D,Sc.M (Committee Member) Subjects: Epidemiology

Doctor of Philosophy, Case Western Reserve University, 2011, Biomedical Engineering

Ca2+ cycling between the cellular and subcellular compartments plays an important role in regulating cardiac contraction. Disturbance in Ca2+ handling occurs in heart failure and is closely related to abnormal contractile performance. The influx of extracellular Ca2+ through L-type calcium channel is the trigger and a key player in the Ca2+ cycling process. However, there are limited ways to measure it in vivo. Recently, manganese (Mn2+)-enhanced MRI (MEMRI) has been proposed as a promising probe to assess Ca2+ uptake because Mn2+ also enters the cell through the Ca2+ channels. However, quantitative analysis and substantial validation are still lacking, which has limited the application of MEMRI as an in vivo method for quantitative delineation of the Ca2+ influx rate. In the current thesis project, a quantitative MEMRI method was developed and validated using small animal models. The sensitivity to subtle alterations in Ca2+ influx rate was demonstrated in a qualitative MEMRI study using a genetically manipulated mouse model that manifested slightly altered L-type Ca2+ channel activity. To provide quantitative estimation of Mn2+ dynamics, fast T1 mapping techniques were developed based on the direct linear relationship between Mn2+ concentration and proton R1. An ECG-triggered saturation recovery Look-Locker (SRLL) method and a model-based compressed sensing method was developed and validated, respectively. When these two methods were combined, rapid T1 mapping (< 80s) of both myocardium and blood were achieved at high spatial resolution (234x469 μm2). Subsequently, a kinetic model was developed to determine Ca2+ influx rate from the quantitative MEMRI measurements. The robustness and accuracy of estimated Ca2+ influx rate was validated using perfusion MEMRI datasets with L-type Ca2+ channel activity well controlled by buffer ingredients. In conclusion, the accomplishment of this project provides a robust MEMRI method for in vivo quantification of L-type Ca2+ (open full item for complete abstract)

Committee: Xin Yu (Committee Chair); Chris Flask (Committee Member); Mark Griswold (Committee Member); David Rosenbaum (Committee Member); David Wilson (Committee Member) Subjects: Biomedical Engineering; Biomedical Research; Medical Imaging; Radiation; Radiology

Master of Science in Occupational Health (MSOH), University of Toledo, 2013, College of Medicine

Occupational exposure to airborne manganese (Mn) is currently determined using National Institute for Occupational Safety and Health (NIOSH) and Occupational Safety and Health Administration (OSHA) analytical methods for particulate not otherwise regulated. The Institute of Occupational Medicine (IOM) dual fraction sampler is capable of providing both inhalable and respirable portions of airborne particles by using only one sampling device. For this study, the IOM dual fraction sampler was compared with OSHA method ID-125G for determining occupational exposure to airborne Mn contaminant during Shielded Metal Arc Welding (SMAW), which was performed in a barge at a marine facility. An aluminum cyclone was used with a 25-mm Mixed Cellulose Ester (MCE) filter to sample respirable Mn contaminants. A 25-mm MCE filter was also used to sample total Mn contaminants. All monitoring was performed by area sampling. The aluminum cyclone readings, except one, were consistently higher than those of the IOM dual sampler (respirable) readings; statistically speaking, the aluminum cyclone showed significantly (p < 0.01) more exposure than did the IOM dual sampler (respirable). Therefore, the findings of this study suggest that the IOM dual sampler is not recommended as an alternative to the aluminum cyclone for the sampling of respirable Mn contaminants. However, the readings of conventional total particle sampler were not significantly different from those of the IOM dual sampler (inhalable). Inhalable and total are compared in this study and the results support the conversion factor of 1.0, which is for welding fume. Therefore, the IOM dual sampler can be used as an alternative method to conventional total particle sampler.

Committee: Farhang Akbar (Committee Chair); Sheryl Milz (Committee Member); April Ames (Committee Member) Subjects: Public Health

Master of Arts, The Ohio State University, 1921, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, The Ohio State University, 1950, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, Miami University, 2024, Chemical, Paper and Biomedical Engineering

Cyclohexane is used in the production of consumer products and fuels and as a solvent. Based upon its industrial relevance, cyclohexane was selected as a representative volatile organic compound (VOC) with which to investigate the role of metal oxide supports in potassium/manganese (K/Mn) – based catalysts. Mn-based catalysts are effective catalysts due to their several oxidation states, mobility of oxygen vacancies, and redox properties. Cryptomelane, a K/Mn-based catalyst material, has been shown by others to be an effective VOC oxidation catalyst. In this study, K/Mn-based catalysts supported on various metal oxide materials were investigated for cyclohexane deep oxidation. The short-term activity of K/Mn on supports followed the trend: Fe3O4 > MnO2 > Al2O3 > TiO2 > SiO2. The performance of Fe3O4-supported and MnO2-supported catalysts with varying K/Mn and Mn loadings were investigated further. The catalysts were characterized for surface area, pore size, morphology, crystallinity, and crystal structure. At 350°C, the catalysts with the lowest loading of 0.63 mmoles K/Mn/g Fe3O4 exhibited the best short-term catalytic activity in the deep oxidation of cyclohexane, while 0.63 mmoles K/Mn/g MnO2 performed best over 95 hours. FTIR spectroscopy was used to assess partial oxidation product build-up on used catalysts.

Committee: Dr. Catherine Almquist (Advisor) Subjects: Chemical Engineering

Doctor of Philosophy, The Ohio State University, 2023, Materials Science and Engineering

Ultra-wide-bandgap (UWBG) materials-based power electronic devices suffer from unexpected and uncertain locations of non-uniformity, and high fields degrade these devices, limiting their lifetimes. It is a challenge to identify the exact locations of breakdown (hot spots), and often destructive processes are used, which are costly, time- consuming, and often not realistic. The work presented here is an attempt to demonstrate a non-destructive and reliable photocurrent spectroscopy technique based on the exciton Franz-Keldysh effect in probing the local electric field (F). By including the excitonic effect in quantitatively modeling the absorption lineshape (and, in turn, photocurrent responsivity), F values are estimated while exploring a wide range of physics. A probe that measures F locally is an extremely useful tool for mapping out the F distribution, performing reliability testing, locating hot and cold spots, validating, or refining electrostatic models, and optimizing device geometry. Analyzing the F-dependent responsivity has shed insight into the contributions of self-trapped excitons and self- trapped holes in 𝛽 − 𝐺𝑎2𝑂3 to the photocurrent-production pathway. Polarization- dependent photocurrent spectroscopy is also performed to verify various excitonic transitions, identify the crystallographic axes, and understand their behavior with the applied bias. For solar-blind photodetectors, light polarization could help to make PDs more selective to deep UV waveleng

Committee: Roberto Myers (Advisor); Andrea Serrani (Committee Member); Tyler Grassman (Committee Member); Wolfgang Windl (Committee Member) Subjects: Electrical Engineering; Engineering; Materials Science

Doctor of Philosophy (PhD), Ohio University, 2022, Chemistry and Biochemistry (Arts and Sciences)

Carbon monoxide (CO) is a toxic gas that has been known as the “silent killer” for decades. At high concentrations, CO reacts with hemoglobin, impairing its ability to transfer oxygen throughout the body. At low concentrations, however, CO has anti-cancer and anti-inflammatory effects. CO has also been shown to increase the sensitivity of certain types of cancer cells to the reactive oxygen species (ROS) produced by chemotherapeutics, thereby reducing drug resistance. One way to deliver CO in a controlled and safe manner is through the use of photoCORMs, or photoactivated CO releasing molecules. Transition metal-based photoCORMs are a class of molecules that release CO by breaking the M-CO bond upon exposure to light. In Chapters 2 and 3, my research study the effect of ligand set variation (both electronically and sterically) around the Mn(I) metal center on the photophysical and photochemical properties, as well as the assignment of photochemical intermediate formation during visible light irradiation. In Chapter 4, we designed a system that combined photo-activated CO delivery and singlet oxygen (1O2). The photophysical and photochemical properties of two Mn(I)-based photoCORMs sensitized with a luminescent BODIPY, as well as their ability to generate singlet oxygen during visible light irradiation were investigated.iv In Chapter 5, my focus was on water-soluble 3D supramolecular coordination cages (SCCs). The internal cavity incorporated in these structures allows them to encapsulate various guest molecules. Water-soluble Ln(III)-based SCCs are scarce, and the arrangement of water molecules inside the cavity, as well as the recognition properties of the latter, are mostly unknown. The study of such interactions would be of interest to the growing field of SCCs. To this end, we designed and synthesized a water-soluble Eu(III)-based supramolecular coordination cage with the general formula of Eu2L3 and a triplestranded helicate structure. T (open full item for complete abstract)

Committee: Eric Masson (Advisor) Subjects: Chemistry

Doctor of Philosophy (PhD), Ohio University, 2022, Chemistry and Biochemistry (Arts and Sciences)

The goal of this research was to design and study new systems of light activated molecules to deliver therapeutic agents. The impact of structural variation on spectroscopic properties as well as changes in photoinduced release of therapeutic molecules is reported herein. Chapter 2 reports complexes with the general structure [(bpy)2Ru(BL)Mn(CO)3Br](PF6)2 where the BL = 2,3-bis(2-pyridyl)pyrazine (dpp) and 2,2ʹ-bipyrimidine (bpm) and bpy = 2,2ʹ-bipyridine. Each of the bidentate bridging ligands exhibit different degrees of π-accepting ability when bridging two metal cations. The impact of the choice of bridging ligand on the photoactivated release of both CO and singlet oxygen (1O2) is reported. This report is the first example of a Ru(II),Mn(I) bimetallic complex with photoactivity in the phototherapy window (600 – 900 nm). The complexes were found to be stable in the dark and only released CO and singlet oxygen upon exposure to visible light. Chapter 3 extends the types of photoactivity of the complexes to include photoactivated DNA intercalation, along with CO release and 1O2 production. The framework used in this study was [(bpy)2Ru(tpphz)Mn(CO)3Br](PF6)2 where bpy = 2,2ʹ-bipyridine and tpphz = tetrapyrido[3,2-a:2′,3′-c:3′′,2′′-h:2′′′,3′′′j]phenazine. The previously studied [Ru(bpy)2(tpphz)](PF6)2 complex has the ability to intercalate between the base pairs of DNA, which can inhibit cell proliferation, as well as a high production efficiency of singlet oxygen when exposed to light. This study used the framework studied in chapter 2 and incorporated the tpphz as a bridging ligand component. The purpose of this study was to test if the addition of the Mn moiety would continue to allow interaction of the tpphz to DNA or inhibit it. The study found that the complex is stable in the dark and inhibits DNA intercalation in the dark. When exposed to visible light, the Mn component dissociates from the complex, freeing the tpphz to then intercalate into DNA. To the (open full item for complete abstract)

Committee: Jessica White (Committee Member); Eric Masson (Advisor) Subjects: Chemistry; Inorganic Chemistry

Master of Science, Miami University, 2022, Cell, Molecular and Structural Biology (CMSB)

Polyphenols have been investigated for their roles in plant science, including resistance to pathogens and predators and potential human health benefits. Polyphenols are abundant in environment and are structurally diverse. My project focused on polyphenols and two metal-protein systems. One project explored epigallocatechin gallate (EGCg) and the serum albumin-Cu(II) complex. EGCg is a bioactive phytochemical with antioxidant activity, while copper is an essential micronutrient. Copper binds to serum albumin at two sites, the high affinity NTS site and the lower affinity MBS site. EGCg also binds to albumin and chelates and possibly reduces Cu(II). I evaluated whether Cu(II), EGCg and albumin form a ternary complex using fluorescence, UV/Vis and EPR spectroscopy. Our results suggest EGCg reduces serum albumin-Cu(II)MBS to Cu(I) but has minimum effects on albumin-Cu(II)NTS. Another project focused on the possible degradation pathway of condensed tannin by the soil manganese peroxidase (MnP) by using monomers, (+)-catechin, (-)-epicatechin, and dimer B2. Condensed tannin degradation by the soil microbiome, which is critical to carbon cycle and ecology, is vastly unknown. Our findings highlight the importance of enzyme catalyzed reaction in the oxidation related CT degradation, and we also propose the possible role of structural features in the oxidation of CT.

Committee: Ann Hagerman (Advisor); Meixia Zhao (Committee Member); Carole Dabney-Smith (Committee Member) Subjects: Biochemistry; Pharmacology; Soil Sciences

Doctor of Philosophy, University of Akron, 2021, Integrated Bioscience

Caves provide a unique environment for studying microbial ecology, providing a portal to the microbial communities of the terrestrial subsurface. Despite the geologic isolation and nutrient limitation of growth in the subsurface, caves contain remarkably diverse microbial communities, with unique adaptations that allow community subsistence and growth. At Wind Cave National Park, South Dakota, a series of lakes are formed at the intersection of Wind Cave and the regionally important Madison aquifer. These lakes (WCL), provide a rare natural window into the aquifer, and my research has demonstrated that they allow us to examine the microbial community of a karst aquifer without the sources of contamination often associated with surface drilling. Though the isolation (125 m below the surface) and long residence time (~25 years) of water en route to the lakes results in ultraoligotrophic conditions (0.29 mg L-1 TOC), the lakes support a stable and diverse community of microbes, albeit with cell numbers lower than almost any body of water on Earth (~2,300 cells mL-1). This low biomass, combined with a reduced cell size as an adaptive strategy to survival in these nutrient limited conditions, made collecting sufficient cell mass for DNA based analyses problematic. I therefore optimized the standard techniques used to sample aquatic communities, using tangential flow filtration to filter more than 1,000 L of water from the Madison aquifer, through a 45 nm-pore size membrane allowing the capture of even the smallest cells within this microbial ecosystem. Metagenomic sequencing combined with comparative filtration revealed that WCL was enriched in ultrasmall cells, such as those found in the Patescibacteria and Nitrospirota. Evidence of integron-facilitated genetic plasticity suggests that metabolic flexibility is an important mechanism for adaptation and survival in WCL. Finally, our metagenomic and phylogenetic data suggest that manganese plays a central role in primary p (open full item for complete abstract)

Committee: Hazel Barton (Advisor); John Senko (Committee Member); Michael Konopka (Committee Member); Zhong-Hui Duan (Committee Member); R. Joel Duff (Committee Member) Subjects: Biogeochemistry; Biology; Microbiology

PhD, University of Cincinnati, 2021, Medicine: Epidemiology (Environmental Health)

Background: Manganese (Mn) toxicity is most often a result of industrial point sources, as Mn compounds are emitted from metal processing factories. Environmental Mn exposure has been linked to deficits in neuromotor function. Marietta, Ohio is home to the longest operating ferromanganese refinery, the top source of ambient Mn in North America. In this community-based longitudinal cohort study of children living near the refinery, we investigate the relationship between childhood and adolescent exposure to Mn and adolescent neuromotor function. Methods: A literature review was conducted to evaluate the current body of knowledge surrounding pediatric Mn exposure and neuromotor function. Participants in the Communities Actively Researching Exposures Study (CARES) provided biological specimens of blood, hair and toenails at a childhood visit conducted at ages 7-9 years. Blood was analyzed for manganese (Mn), lead (Pb) and serum cotinine, a marker of environmental tobacco smoke. Hair and toenails were analyzed for Mn. Study participants returned during adolescent years 13-17 for collection of biological specimens of blood and hair and evaluation of neuromotor function through postural balance testing. Blood was analyzed for Mn, Pb and serum cotinine and hair for Mn. Geometric means (GM) and geometric standard deviations (GSD) were calculated for biomarker concentrations and arithmetic means and standard deviations (SD) and frequencies for sociodemographic information of participants. Multivariable regression models were employed to examine the relationships between childhood and adolescent Mn exposure and adolescent postural balance, adjusting for covariates. Secondary analyses were conducted to visually examine plots with fitted splines and gender-by-Mn interaction effects on postural balance. Results: The CARES participants who completed adolescent postural balance testing were 54% female and 98% Caucasian. The mean age was 16 years old (range 13-17). (open full item for complete abstract)

Committee: Amit Bhattacharya Ph.D. (Committee Chair); Heidi Sucharew (Committee Member); Erin Haynes Dr.P.H. (Committee Member); Kelly Brunst Ph.D. (Committee Chair) Subjects: Epidemiology

PhD, University of Cincinnati, 2020, Medicine: Epidemiology (Environmental Health)

Introduction: Manganese (Mn) is an essential trace element necessary for normal growth and development, that in excess can be neurotoxic. Excess environmental Mn can occur due to industrial emissions, but exposure pathways from environmental sources to biomarker levels, and ultimately to neurological outcomes have not been determined. Objectives: The objectives of this dissertation are to 1) determine ambient air Mn exposure levels in a population living near the longest operating ferromanganese refinery in North America, using atmospheric dispersion modeling, 2) evaluate associations between modeled ambient air, soil, and indoor dust Mn collected from residences in the exposure area, and 3) determine pathways from environmental measures of Mn to blood, hair, and toenail Mn levels in exposed children using structural equation modeling (SEM). Methods: Data are from the Communities Actively Researching Exposure Study (CARES), a cross-sectional study conducted from 2008-2013 in the Marietta, Ohio area to investigate neurological effects of Mn exposure in 7-9 year old children. Emissions from the Mn refinery were modeled using the U.S. Environmental Protection Agency (EPA) regulatory air dispersion model AERMOD. Average annual ambient air Mn concentrations were determined for census blocks within 32 km of the refinery, and for CARES participants' homes and schools. Monthly modeled ambient air concentrations for 2009-2010 were compared to concentrations from a stationary air sampler in Marietta to evaluate accuracy of the model. Exposures by census blocks were determined to estimate population sizes exposed to air Mn levels exceeding 50 ng/m3, the U.S. EPA guideline. SEM was performed to determine pathways of exposure from air, soil, and indoor dust Mn separately for blood, hair, and toenail Mn. Additional data included in the models were heating, ventilation and air conditioning in the home, average hours/week spent outside by the participant, parent education, (open full item for complete abstract)

Committee: Kelly Brunst Ph.D. (Committee Chair); Florence Fulk Ph.D. (Committee Member); Erin Haynes Dr.P.H. (Committee Member); Tiina Reponen Ph.D. (Committee Member); Heidi Sucharew Ph.D. (Committee Member) Subjects: Epidemiology

Doctor of Philosophy, Miami University, 2020, Geology and Environmental Earth Science

Modern civilization as we know it today could not exist without heterogeneous catalysis as it underpins all development in applied chemistry, materials science, and environmental geochemistry. Catalysts allow important chemical reactions such as the production of agricultural fertilizer, the formation of petrochemicals, and the breakdown of environmental pollutants to occur with lower energy thresholds. Catalysts comprise a diverse group of materials but none quite as important as porous solids, which optimize surface area, facilitate catalyst recyclability, and impart important selective properties. Many porous materials are naturally occurring minerals such as transition metal oxides, phyllosilicates, zeolites or complex compounds of minerals. This dissertation relates efforts to create and explore novel mineral catalysts whose catalytic properties are directly related to their microporosity, that is, minerals whose pores are less than 2 nanometers in diameter. In the first project, cryptomelane - a manganese oxide with a square tunnel-based framework - was synthesized in the absence and presence of an aqueous growth medium and doped with europium during and after crystallization to investigate Eu's effects on cryptomelane's physical, chemical, and catalytic properties in a temperature-dependent oxidation reaction. It was determined that the position of Eu in the cryptomelane framework strongly affected its catalytic activity. In the second project, sepiolite - a phyllosilicate mineral with a ribbon-like crystal structure and high specific surface area - was modified with manganese and europium prior to in-situ growth and deposition of nanocrystalline titanium dioxide to investigate the effects of support-doping vs. catalyst-doping in a photocatalytic reaction under different ultraviolet radiations. It was determined that phyllosilicate support promoters have variable behavior during multi-step catalyst preparation which ultimately impacted the photocatalytic acti (open full item for complete abstract)

Committee: Mark Krekeler (Advisor); John Rakovan (Committee Member); Claire McLeod (Committee Member); Catherine Almquist (Committee Member); Peter Heaney (Committee Member) Subjects: Chemical Engineering; Environmental Geology; Materials Science; Mineralogy

PhD, University of Cincinnati, 2019, Medicine: Epidemiology (Environmental Health)

Background: Exhibiting a dual role with regards to human health, manganese (Mn) is necessary in trace quantities; however, at increased exposure levels, the metal poses a risk to neurologic functions. Previous studies have described negative associations between elevated concentrations of Mn and neurodevelopmental deficits. Additionally, supporting the dual role of Mn as both a nutrient and a neurotoxicant, a biphasic dose-response relationship between Mn exposure and cognition has been described. In particular, children are extremely vulnerable to neurologic insults and negative impacts during the early years may persist. Therefore, this dissertation aims to understand the impact of Mn exposure on cognition among school-age children living in Appalachian Ohio. Methods: First, a literature review was conducted to gain an understanding of previous studies examining Mn and cognition and identify gaps in the research. Utilizing the Communities Actively Researching Exposure Study (CARES), we analyzed Mn exposure data (Blood: MnB, Hair: MnH and Toenails: MnT) and cognitive measures (academic achievement and intelligence quotients (IQ)) among school-aged children living in eastern Ohio, an area with excess environmental exposure to Mn. We calculated geometric means (GM) and frequencies for sociodemographic information and metal concentrations in biological specimen. We explored linear dose-response associations through adjusted multiple regression models. Due to the biologic necessity of Mn, we additionally assessed nonlinear relationships. Results: The majority of the CARES participants are Caucasian and have parents with greater than 12 years of education. The GMs were as follows: MnB: 9.73 µg/L; MnH: 405.26 ng/g; MnT: 0.67 µg/g (Chapter 4). Mn concentrations measured in hair and toenails were significantly correlated [r = 0.34 p = <0.001 (Chapter 3); r = 0.37 p =0.0001 (Chapter 4)]. After adjustment for covariates, there were no significant associations between (open full item for complete abstract)

Committee: Kelly Brunst Ph.D. (Committee Chair); Kim Dietrich Ph.D. (Committee Member); Erin Haynes Dr.P.H. (Committee Member); Heidi Sucharew Ph.D. (Committee Member) Subjects: Epidemiology

Master of Science, The Ohio State University, 2019, Earth Sciences

Manganese (Mn) plays a critical role in river water quality since Mn-oxides serve as sorption sites for contaminant metals such as copper, zinc, and lead. Here, I measure and model annual changes in river water-groundwater interaction and Mn(aq) transport in an alpine streambed influenced by spring snowmelt (East River, Colorado). In field observations and models, oxygenated river water containing dissolved organic carbon (DOC) mixes with groundwater rich in reduced manganese in the riverbed. The depth of mixing is greatest during spring snowmelt when river discharge is greatest, leading to an influx of DOC, dilution of Mn(aq), and net respiration of Mn-oxides, despite an enhanced supply of oxygen. Conversely, a shift to upwelling conditions over the subsequent baseflow period allows for groundwater rich in Mn(aq) to mix with oxygenated river water in the shallow subsurface, resulting in net accumulation of Mn-oxides until the bed freezes in winter. To explore potential responses of Mn transport to different climate-induced hydrological regimes, I model three hydrograph scenarios (Historic, Low-snow, and Storm) for the Rocky Mountain region. In a warming climate with less snowpack and a longer baseflow season, Mn(aq) oxidation will be favored in the upper riverbed sediments over more of the year, which may increase the sorption capacity of the streambed for other metals.

Committee: Audrey Sawyer (Advisor); Elizabeth Griffith (Committee Member); Allison MacKay (Committee Member) Subjects: Biogeochemistry; Environmental Science; Hydrologic Sciences