Doctor of Philosophy, The Ohio State University, 1981, Graduate School

Committee: Not Provided (Other) Subjects: Biology

Master of Science, The Ohio State University, 1970, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, The Ohio State University, 1971, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, The Ohio State University, 1969, 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 in Chemistry, Youngstown State University, 2023, Department of Biological Sciences and Chemistry

Today's society is mainly dependent on fossil energy sources despite being not sustainable, not renewable, and not environmentally friendly, as they generate a lot of carbon dioxide. Hydrogen is a promising substitute for fossil fuels. It is a clean fuel with water as the only oxidation product, thus less production of CO2. Cadmium telluride (CdTe) is a promising semiconductor material that could facilitate the use of solar energy in producing hydrogen gas. CdTe can be a p-type photoelectrode that can perform electron transfer processes with an electrolyte. As a cathode, it reduces hydrogen ions in water to form hydrogen gas. Spray pyrolysis method, which is simple and easy to use, cheap compared to vacuum deposition methods, can produce uniform films over large surfaces within a short time, many small substrates at the same time, and whose concentration of precursor solution remains constant with time, was used in this project. CdTe films for this project were fabricated on stainless steel 304 substrates at different substrate temperatures and spray times. The precursor solution was based on a mixture of CdCl2, TeO2, hydrazine, and EDTA. Characterization of the fabricated films was done using X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS), stylus profilometry, cyclic voltammetry, and linear sweep voltammetry. The fabricated CdTe films had a uniform and highly crystalline surface morphology, that was Te-rich (p-type) and exhibited photoactivity with the evolution of hydrogen gas. The best photoelectrode was fabricated by spraying a mixture of equal volumes of 0.02 M solutions of Cd and Te salts onto a SS 304 substrate held at 330°C for 3 min, which produced a 10 µm-thick film and a photocurrent of 5800 µA/cm2 observed at -0.5 V. When a dispersion of Pt catalyst was reduced onto it, a photocurrent of 7700 µA/cm2 was observed at -0.5 V, which compares well with other fabrication methods.

Committee: Clovis Linkous PhD (Advisor); Christopher Arntsen PhD (Committee Member); Allen Hunter PhD (Committee Member); Joe Simeonsson PhD (Committee Member) Subjects: Analytical Chemistry; Chemistry

Doctor of Philosophy, University of Toledo, 2022, Physics

Solar energy is a powerful and essential source of renewable energy that works on the principle of the photovoltaic (PV) effect. Among all photovoltaic cell technologies, silicon (Si) dominates with a market share of ~ 90% of the PV industry. Though Si is highly efficient, cadmium telluride (CdTe) competes very effectively with crystalline Si (c-Si) for utility-scale PV and offers advantages in terms of energy payback time (EPBT) and low water impacts. Antimony sulfide (Sb2S3) absorber is an exploratory absorber material with favorable properties like earth abundance, a tunable band gap, and a high absorption coefficient. It also has the potential to serve as a top cell absorber for tandem PV technologies. CdTe is an II-VI semiconductor material with a direct band gap of 1.45 eV. Single junction polycrystalline CdTe solar cells have reached a certified photoconversion efficiency (PCE) of 22.1%. According to the Shockley-Queisser limit, for a material having a band gap of 1.45 eV, the theoretically attainable efficiency is 33.1%, suggesting ample room to improve the CdTe device's efficiency. The low PCE in CdTe is primarily due to the device's low open circuit voltage (VOC) and fill factor (FF). CdTe has a deep valance band edge of 5.9 eV below the vacuum level, that creates a barrier at the back interface, limiting hole transport and reduces the device's performance. The suitable implementation of a back buffer layer between the CdTe absorber and the back electrode is vital in improving monofacial and bifacial CdTe device performance. This dissertation addresses the synthesis and characterization of tellurium (Te) and lead telluride (PbTe) nanowires (NWs), copper iodide (CuI) nanoparticles, copper chromium oxide (CuxCryOz), and their applications to fabricate monofacial and bifacial solar cells based on CdTe as well as CdSexTe1-x absorber layers. In addition, the dissertation presents the fabrication and characterization of Sb2S3 solar cells. Tellurium and lead t (open full item for complete abstract)

Committee: Randy J Ellingson (Committee Chair); Yanfa Yan (Committee Member); Nikolas J Podraza (Committee Member); Anne Medling (Committee Member); Xavier Mathew (Committee Member) Subjects: Materials Science; Physics

Doctor of Philosophy, The Ohio State University, 2022, Entomology

Metal contamination, resulting from industrial, mining, transportation, and incineration activities, is ubiquitous in urban and other human dominated areas and poses an understudied yet potentially impactful challenge to pollinator communities. Legacy cities, concentrated in post-industrial regions, are cities that experienced a dramatic economic decline, followed by an exodus of residents which led to an abundance of vacant infrastructure and land that is oftentimes contaminated with metals. Increasing interest in reimagining unused urban land as habitat for bees and other beneficial species has created an urgent need to identify and isolate the impacts of metal exposure on these pollinators. Bees are exposed to and accumulate metals while searching for food and resources within contaminated regions, yet, they and other organisms are readily found within contaminated landscapes despite the potential negative effects of metal exposure. Therefore, the overarching goals of this dissertation research were to determine the lethal limits of metal exposure for bees, investigate the impacts of field relevant concentrations of common urban metals on bumble bee colony health, and asses any sublethal effects of metal exposure on bumble bee foraging behavior. Focusing first on legacy cities' unique opportunities for urban bee habitat with a potential for unintended metal exposure, the first objectives of this research were to review the literature on potential metal exposure routes for pollinators, and if bees are exposed, the impacts of metals on wild bee health, fitness, and behavior (Chapter 1). My next objective was to identify if, and at what concentrations, metal exposure results in forager bee mortality and if bees bioaccumulate any metals within their bodies (Chapter 2). Next, I wanted to identify how exposure to environmentally relevant concentrations of metals arsenic, cadmium, chromium, and lead that bees encounter in cities influence overall Bombus impatiens co (open full item for complete abstract)

Committee: Frances Sivakoff (Committee Member); Roman Lanno (Committee Member); Reed Johnson (Committee Member); Mary Gardiner (Advisor) Subjects: Entomology

Master of Science (MS), Ohio University, 2022, Biological Sciences (Arts and Sciences)

Bats in North America face many threats to their survival, including heavy metal pollution, a less widely studied and understood contributor to bat mortality. Arsenic, cadmium, and lead are three of eleven heavy metals of highest concern for wildlife due to their damaging effects to health at low levels of exposure. The purpose of this study was to better understand trends in concentrations of these metals in the fur of three bat species so as to manage conservation efforts more effectively. To do so, I examined concentrations of arsenic, cadmium, and lead in the fur of big brown bats (Eptesicus fuscus), little brown myotis (Myotis lucifugus) and eastern red bats (Lasiurus borealis) collected from museum samples and bats submitted for rabies testing. Among samples taken from museum collections, little brown myotis had higher arsenic levels in their fur than big brown and eastern red bats. Among big brown bats submitted for rabies testing, the presence of coal-fired power plants in the counties where bats were collected was associated with higher levels of arsenic in fur. Big brown bats with higher concentrations of lead and arsenic in their stomach contents also had greater concentrations in their fur. These data provide additional evidence that bats acquire heavy metals through their prey and that species accumulate metal differently, possibly due to difference in diet.

Committee: Joseph Johnson (Advisor); Viorel Popescu (Committee Member); Willem Roosenburg (Committee Member) Subjects: Ecology; Environmental Science; Toxicology; Wildlife Conservation

Doctor of Philosophy, University of Toledo, 2021, Physics

Polycrystalline Cadmium Telluride has been developed to be one of the most commercially successful materials for photovoltaic module production with power conversion efficiencies over 21% for research cells to over 18% for module efficiencies. However, little is known about these record devices architecture or the processing methods. Following conventional understanding of a CdTe solar cell operation, researchers have put extensive efforts over the years to improve the CdTe device performance through improved material quality and diode quality. While this have gained some benefit, performance limiting factors to these devices remains unchanged. Deviating from conventional concepts, better understanding of the device physics is needed in order to further improve these devices. This dissertation focusses on identifying these loss mechanisms and setting guidelines to fabricating high efficiency CdTe devices through both experimental and numerical simulation. Experimental work discusses the details to construction and characterization of a CdTe deposition system and employing the new understanding of improving the CdTe device to achieve high performing CdTe devices. Here the traditional CdS window layer is replaced by a wide bandgap MgxZn1-xO to increase the photocurrent generation with better band alignment. With optimum deposition and processing conditions, work demonstrates a device with power conversion efficiency >16%. With a good front contact, performance of the device can be limited by the poor back contact. Expanding the understanding to front contact band alignment, characteristics of a back buffer layer suitable for CdTe back contact is also explored. Through 1D numerical simulation of the conduction and valence band offset, doping levels of the CdTe and back buffer layer material, this dissertation work sets the guideline to achieving CdTe device performance up to 25%.

Committee: Michael Heben (Committee Chair); Alvin Compaan (Committee Member); Song Cheng (Committee Member); Yanfa Yan (Committee Member); Randall Ellingson (Committee Member) Subjects: Materials Science; Physics

Master of Science (MS), Bowling Green State University, 2021, Geology

Urban environments have a history of anthropogenic input of heavy metals to soils. Toledo, Ohio is an urban setting that has been altered through heavy industry and transportation dating back to the 1800s. Heavy metal contamination in soil has been shown to cause serious health effects in humans, such as brain damage, birth defects, cancer, and even death. A total of 137 Toledo soil samples were collected in collaboration with local Toledo schools, the Manos Community Garden, and a previous study completed by Stewart et al (2014). Stewart's study samples and the local Toledo schools' soil samples were collected by K-12 students through a hands-on citizen science project. The samples were analyzed to determine the concentrations of a series of heavy metals, including arsenic, cadmium, chromium, lead, nickel, and zinc. The results revealed multiple samples with elevated levels of all six focus metals greater than the Ohio EPA's soil background levels of the region. Two of these elements, arsenic and lead, had concentrations higher than the USEPA screening level for soils of this region in 73% and 7% of samples, respectively. Locations with elevated heavy metals concentrations in soils were mostly residential yards with older houses and within areas of high transportation. Therefore, the elevated levels of heavy metals were likely deposited from a legacy of human activities. Heavy metal predictive concentration maps of the Toledo, Ohio area were created to show possible areas of concern. The predictive maps showed a higher concentration of most elements in the Old West End area of Toledo. The findings were presented to the collaborating schools and in public forums to educate citizens about elevated heavy metal soil contamination in their area. They were given possible reasons for the contamination, explaining the harmful side effects of human activities on the soils. The health risks associated with the contamination were presented along with how to prevent health (open full item for complete abstract)

Committee: John Farver Dr. (Advisor); Jeffrey Snyder Dr. (Committee Member); Margaret Yacobucci Dr. (Committee Member) Subjects: Education; Geochemistry; Geology

Master of Science in Chemistry, Youngstown State University, 2020, Department of Chemistry

Heavy metals are natural elements found in the earth's crust which have dynamic applications in industrial, domestic, and agricultural activities. These human activities have caused their increased distribution to the environment. Science has shown some of these elements such as lead, cadmium, chromium, mercury and arsenic to be toxic to living organisms. Heavy metals are today known to cause cancer, development retardation in children, anemia, and autism, among other diseases. Currently chelation is the state-of-the-art technique in treatment of heavy metal toxicity in humans. However, despite the success stories, lack of selectivity, non-target side effects, redistribution of metals to other parts of the body and low efficiency attributable to chelators calls for alternative ways in treatment and management of heavy metals. One such approach would be the use of metal-organic frameworks (MOFs) in adsorption of heavy metals. MOFs are prepared through reaction of metal ions with multi-topic organic ligands, which assemble to form porous structures. This thesis has two sections. The first section of the document presents the in vitro adsorption capability of the selected metal-organic frameworks. We focused on two zirconium-derived MOFs, thiophene-containing (DUT-67) and non-thiophene containing (UiO-66) for adsorption of heavy metals from water, protein solutions, and Ovis aries's (sheep's) blood. The second section will address an unprecedented behavior of UiO-66 in Pb2+ adsorption. The results obtained in heavy metal adsorption (section one) shows that DUT-67 and UiO-66 have similar adsorption capabilities for Pb2+, Cd2+ and Cr3+ in water, protein solution, and blood samples. Adsorption of the selected heavy metals is noteworthy since Pb2+, Cr3+ and Cd2+ have been known to impose great risk to human health. Additionally, this report shows that these MOFs could selectively adsorb heavy metals from solution leaving behind most of the essential elements, hence reduc (open full item for complete abstract)

Committee: Douglas Genna PhD (Advisor); Nina Stourman PhD (Committee Member); Christopher Arntsen PhD (Committee Member) Subjects: Chemistry; Environmental Health; Environmental Management; Environmental Science; Materials Science; Therapy; Toxicology

Master of Science (MS), Wright State University, 2020, Physiology and Neuroscience

Humans are exposed daily to a variety of metals that can be harmful to our immune system. Although certain divalent metal cations are essential for numerous cellular functions and are critical trace elements in humans, the uptake mechanisms of these ions remain mostly unknown. Transient receptor potential melastatin 7 (TRPM7), which is expressed in a variety of human cell types, including lymphocytes and macrophages, conducts many divalent metal cations. TRPM7 channels are largely inactive under normal physiological conditions due to cytoplasmic magnesium acting as a channel inhibitor. Magnesium is a cofactor for many biochemical reactions. Low serum levels of magnesium, hypomagnesemia, can occur from increased magnesium loss from renal or gastrointestinal systems, redistribution of magnesium across the cell membranes, and decreased magnesium intake. Magnesium depletion allows both physiological and non-physiological divalent metal cations to enter through TRPM7, which is highly expressed in T-lymphocytes. Alterations to TRPM7 channel activity by channel blockers were found to affect the cell viability sequence. Through the use of Jurkat, a leukemic T-lymphocyte cell line which expresses high levels of TRPM7, HAP1 cells, and a TRPM7 kinase-dead mouse model, the entry of both physiological and non-physiological cations can be quantitated by measuring cell toxicity. A cell toxicity/viability assessment in Jurkat T-lymphocytes provided the sequence of Cd2+ > Zn2+ > Co2+ > Ni2+ > Mn2+ >> Sr2+ ≈ Ba2+ ≈ Ca2+ ≈ Mg2. Homeostatic mechanisms alter the effects of divalent metal cation entry and viability of T-lymphocytes, suggesting that TRPM7 in part contributes to metal ion entry.

Committee: Juliusz Ashot Kozak Ph.D. (Advisor); Christopher N. Wyatt Ph.D. (Committee Member); David R. Ladle Ph.D. (Committee Member) Subjects: Cellular Biology; Immunology; Pharmacology; Physiology

Bachelor of Science, Ashland University, 2020, Biology/Toxicology

Most exposures to the toxic heavy metal cadmium come through consumption of trace amounts in food and tobacco smoke. However, cadmium is often used to make jewelry due to its shiny appearance, low cost, and low melting point. This can result in additional exposure to children who mouth or swallow these items. While jewelry may not be marketed directly to children, it may be obtained by children due to low cost (typically around $1-$5). The U.S. currently does not regulate the cadmium content of jewelry that is not considered children's jewelry. The objective of this study was to determine the potential for high-cadmium jewelry to release cadmium if mouthed or swallowed by children. Eighty inexpensive jewelry samples were screened for cadmium by X-ray fluorescence. High-cadmium samples were extracted at body temperature with dilute NaCl to simulate mouthing and dilute HCl to simulate digestive action. After initial extractions, jewelry pieces were damaged to determine whether damage to the outer surface increased cadmium release. After extractions were complete, the total cadmium content of the samples was determined. Cadmium concentrations for all solutions were determined by atomic absorption (AA) spectrometry. Thirty-four total replicates of nine jewelry items were extracted as described. The average cadmium release from initial NaCl extractions was 727 µg, and from initial HCl extractions was 66.3 µg. After damage, the average release of cadmium from the NaCl extractions was 3400 µg, and from HCl extractions was 26300 µg. The comparable voluntary standards that have been adopted by the U.S. Consumer Product Safety Commission (CPSC) are a maximum release of 18 µg for NaCl extractions, and 200 µg for HCl extractions (U.S. CPSC 2011). The high levels of extractable cadmium underscore the danger posed by this jewelry.

Committee: Jeffrey Weidenhamer (Advisor); Doug Dawson (Other) Subjects: Biology; Chemistry; Toxicology

PhD, University of Cincinnati, 2017, Medicine: Epidemiology (Environmental Health)

Background: CBS's 60 Minutes ran an episode entitled “Following the Trail of Toxic E-waste” in 2008 and gave Americans, and the world, a firsthand look at informal electronic waste (e-waste) recycling. E-waste is the fastest growing solid waste stream worldwide with the United Nations Environmental Programme (UNEP) estimating that 50 million metric tons by the end of 2018. It contains many valuable metals that can be recycled and resold, however it also contains many harmful chemicals, such has lead (Pb), cadmium (Cd), hexavalent chromium (Cr[VI]), and manganese (Mn). Informal e-waste recycling involves methods that can lead to widespread contamination and adverse health effects, especially in pregnant women and children. Methods: Using data from the E-waste Recycling and Community Health (e-REACH) study, we measured Pb, Cd, Cr, and Mn from pregnant women who were enrolled at delivery from Guiyu (n=314), the exposed site, and Haojiang (n=320), a community with no history of informal e-waste recycling, from 2011-12. We calculated the geometric mean (GM) and recorded the minimum and maximum values for each metal in maternal blood, cord blood, and maternal urine for both sites. The ratio of each metal concentration in each of the biospecimens between Guiyu and Haojiang were calculated using linear regression. Relative risks (RR) were calculated for elevated blood Pb in mothers. We compared the differences in birth weight, birth length, head circumference, body mass index (BMI), and Ponderal index (PI). Odds ratios (OR) for small for gestational age in association with each metal concentration in the biospecimens were calculated. Finally, we used a structural equation model (SEM) to create an overall latent variable from each metal and examine its association with neonatal BMI. Results: Guiyu mothers had higher concentrations of Pb (ratio: 1.74, 95% CI: 1.60, 1.89), Cd (ratio: 1.31, 95% CI: 1.15, 1.48), and Cr (ratio: 1.52, 95% CI: 1.34, 1.73) in their blood c (open full item for complete abstract)

Committee: Aimin Chen Ph.D. (Committee Chair); Kim Dietrich Ph.D. (Committee Member); Tiina Reponen Ph.D. (Committee Member); Heidi Sucharew Ph.D. (Committee Member); Changchun Xie Ph.D. (Committee Member) Subjects: Epidemiology

Master of Science (MS), Ohio University, 2017, Geological Sciences (Arts and Sciences)

Urban runoff can come into contact with a range of pollutants. Metal pollutants can pose an especially significant threat to water quality. This study focused on metals: Cd, Zn, Cu, Pb, Fe and Mn. These metals were chosen after previous studies reported finding them in first flush stormwater collected throughout the Midwestern US. This study tested the effectiveness of SR-HP forms to remove metals from DI water with standard solutions of metals added. Two sizes of SR-HP forms were constructed from sodium percarbonate (Na2CO3·1.5H2O2) salts and resin and release rates were quantified. The smaller size released hydrogen peroxide (H2O2) at a steady average rate of 0.063 mg/min after 6.2 hours. One proof-of-concept treatment test was conducted utilizing smaller SR-HP forms and DI water containing dissolved metals. During the treatment test, SR-HP released H2O2 and alkalinity at the rates ranging from 1.35 mM to 0.135 mM and 0.90 mM to 0.09 mM, respectively. The pH of metal loaded deionized water was raised from 1.74 to 1.87 indicating slight neutralization by added carbonate. This resulted in removal efficacies ranging from 4.17% - 0.65%, 4.52% - +0.76%, 8.59% - 2.92%, 7.44% – 0.29%, 0.52% - +2.24% for Cd, Cu, Fe, Pb and Zn respectively. No consistent treatment was evident for all metals except for iron, which saw a modest removal of 8.6%. This 8.6 removal was most likely due to Fe2+ being used during Fenton's reaction. This result indicates effective removal by SR-HP could be feasible, especially if the pH is more alkaline. Further investigation of SR-HP form performance in a wide range of pHs could be possible.

Committee: Eung Seok Lee (Advisor); Greg Nadon (Committee Member) Subjects: Analytical Chemistry; Aquaculture; Aquatic Sciences; Area Planning and Development; Chemical Engineering; Chemistry; Environmental Geology; Environmental Science; Environmental Studies; Experiments; Geology; Hydrologic Sciences; Hydrology; Organic Chemistry

Doctor of Philosophy, The Ohio State University, 1987, Graduate School

Committee: Not Provided (Other) Subjects: Biology

Doctor of Philosophy, The Ohio State University, 1986, Graduate School

Committee: Not Provided (Other) Subjects: Biology

Doctor of Philosophy, The Ohio State University, 1981, Graduate School

Committee: Not Provided (Other) Subjects: Education

Doctor of Philosophy, The Ohio State University, 1981, Graduate School

Committee: Not Provided (Other) Subjects: Biology