Master of Science, University of Toledo, 2006, Biology (Ecology)

It is well known that invasive species, such as the dreissenid mussels in the Great Lakes, play significant roles in changing the substrate, community species composition, and habitat. This study examined the role of Dreissena, (zebra mussel, D. polymorpha and quagga mussel, D. bugensis) as an invasive “paver”, which compacts the sediment, and its effects on two native bioturbators, Hexagenia (burrowing mayflies; H. limbata and H. rigida) and unionid bivalve mollusks. Resulting consequences on sediment properties, infaunal invertebrates, and microbial community composition were analyzed. I further examined the spatial relationship between Dreissena and Hexagenia. Experiments showed that Hexagenia density increased in the presence of Dreissena, nematodes decreased, and oligochaetes and microbes were unaltered. In the absence of Dreissena, bioturbating species altered sediment water content and increased infaunal invertebrate densities, microbial activity, and microbial functional diversity. In further exploration of the relationship between Dreissena and Hexagenia, Hexagenia preferred habitat with 50-100% spatial coverage of live Dreissena clusters. These experiments thus revealed habitat facilitation by an invasive ecosystem engineer on a native ecosystem engineer, Hexagenia, with opposite effects on invertebrates, microbes, and sediment properties.

Committee: Christine Mayer (Advisor) Subjects:

Master of Science, The Ohio State University, 2023, Human Ecology: Human Nutrition

Safe and nutritious fresh produce is crucial for public health, and hydroponic farming systems play a vital role in sustainable crop production. However, these farming systems also present a favorable environment for the growth of human pathogens, leading to foodborne infections. The objective of this study was to assess the impact of chemical sanitizers on quality (yield, chlorophyll, and carotenoid) of lettuce and basil grown in hydroponic Nutrient Film Technique (NFT) systems. Additionally, the effectiveness of pHmanipulation of nutrient solution and SaniDate 12.0 (200 ppm) in eliminating human pathogen Salmonella Typhimurium and Listeria monocytogenes and their impact on lettuce quality and nutritional attributes (lutein, zeaxanthin, beta-carotene, beta-cryptoxanthin and chlorophyll a) were evaluated. Using a randomized complete block design, various sanitizer treatments were applied to nutrient solution of hydroponically grown lettuce and basil. The crops were monitored for five weeks, and their yield and nutritional composition were assessed. Results showed a detrimental effect of all sanitizer treatments on both lettuce and basil, compared to the nontreated control (p<0.01). However, lettuce and basil treated with 200ppm SaniDate 12.0 showed higher yields than those treated with chlorine sanitizers (p<0.01). An adverse effect was observed for lettuce and basil exposed to 200ppm Na-hypochlorite (lettuce; p=0.041and basil; p=0.027). In terms of human pathogen elimination, none of the treatments (including pH modification and 200ppm SaniDate 12.0) successfully eliminated Salmonella Typhimurium and Listeria monocytogenes from the NFT system. The highest reduction in Salmonella Typhimurium was achieved by SaniDate 12.0 (p<0.001), followed by pH=4(p=0.002), and finally pH=5 (p=1.00) as compared to non-treated control and for Listeria monocytogenes, the highest reduction in pathogen was SaniDate 12.0 (p<0.001), followed by pH=5 (p=0.04), as compared to non-treat (open full item for complete abstract)

Committee: Sanja Ilic (Advisor); Melanie L.L Ivey (Committee Member); Rachel Kopec (Committee Member) Subjects: Agriculture; Education; Food Science; Microbiology

Master of Public Health, The Ohio State University, 2021, Public Health

In production industries, such as aquaculture, there is a lack of invertebrate animal regulation, even with the Red Swamp Crayfish (Procambarus clarkii), which accounts for over $200 million in business for the United States. To Louisiana, crayfish are not only a crucial part of their rich culture, but also an important aspect of their aquaculture industry. Despite this, limited knowledge is available about the potential risks associated with eating farm-raised crayfish in the United States. Current food safety guidance lacks the information specific to crayfish populations within the United States allowing for the correct identification of potential hazards. In addition to food safety, biosecurity and biosafety practices associated with crayfish used in laboratory animal settings are limited. The objectives of this study are to evaluate the specific zoonotic pathogens present on Red Swamp Crayfish (Procambarus clarkii) from the southeastern part of the United States, Alabama & Louisiana, and determine the effectiveness of pathogen reduction in traditional food preparation techniques. Crayfish and their shipping containers were sampled for the presence of Escherichia coli, Salmonella, Staphylococcus aureus, and Vibrio spp. Additional subsets of crayfish were dissected to look for Paragonimus kellicotti. Vibrio was the most prevalent bacteria cultured. One hundred percent of samples collected from live crayfish (60/60) and 81% of all environmental samples (13/16) resulted in characteristic growth. Additionally, only 5% (3/60) samples grew characteristic E. coli colonies. It was also found that traditional cooking techniques were effective in reducing pathogen load in crayfish. One hundred percent (10/10) of live crayfish samples taken before boiling returned characteristic growth of Vibrio, while 10% (1/10) of boiled unseasoned crayfish samples grew minimally characteristic colonies. The remaining zoonotic pathogens, P. kellicotti, Salmonella, and S. aureus were not (open full item for complete abstract)

Committee: Thomas Wittum (Advisor); Raphael Malbrue (Committee Member); Antoinette Marsh (Committee Member); Jennifer Hefner (Committee Member) Subjects: Microbiology; Public Health; Veterinary Services

Doctor of Philosophy, The Ohio State University, 2021, Plant Pathology

Soilborne diseases and weeds contribute to more than 35% of crop yield loss worldwide. These can be managed successfully using an environmentally benign soil disinfestation method known as anaerobic soil disinfestation (ASD) and biocontrol agents (BCAs). These studies focused on developing soilborne pest management strategies that integrate ASD with BCAs. Organic amendments including wheat bran, molasses, and cover crops used as ASD carbon sources were evaluated to manage Rhizoctonia root rot (RRR) caused by Rhizoctonia solani in radish, clubroot disease caused by Plasmodiophora brassicae in mustard greens and several weed species. Forty-one isolates of the fungal BCA Trichoderma collected from diverse climatic zones in Nepal and Ohio were characterized using morphological and molecular techniques and assessed for their biocontrol efficacy in vitro and in planta. The Trichoderma isolates from Nepal were assigned to the Asperellum, Asperelloides and Harzianum clades, while the Ohio isolates were matched to the Hamatum and Ghanense clades based on a maximum likelihood phylogenetic analysis. Potential synergy between two Trichoderma BCAs and ASD in the suppression of RRR in radish and clubroot disease in mustard greens was assessed. Rhizoctonia solani populations were significantly reduced by ASD treatment regardless of carbon source, while Trichoderma populations were not affected by ASD treatment with the exception of ASD-mustard greens. The interactions of either Trichoderma isolate and ASD with most carbon sources were additive, while T. harzianum T22 with ASD-molasses and T. asperelloides NT25 with ASD-wheat bran interactions were synergistic in reducing disease severity. Anaerobic soil disinfestation effectively suppressed weed seed germination and viability when wheat bran, molasses and mustard greens biomass were used as carbon sources. We also analyzed the integration of genetic resistance and induced systemic resistance by Trichoderma isolates as a potential (open full item for complete abstract)

Committee: Sally Miller Dr. (Advisor); Pierce Paul Dr. (Committee Member); Jonathan Jacobs Dr. (Committee Member); Steve Culman Dr. (Committee Member); John Cardina Dr. (Committee Member) Subjects: Agriculture; Plant Pathology

Doctor of Philosophy, University of Toledo, 2017, Electrical Engineering

Electrically conductive hair-like structures, referred to as whiskers, can bridge the gap between densely spaced electronic components. This can cause current leakage and short circuits resulting in significant losses and, in some cases, catastrophic failures in the automotive, aerospace, electronics and other industries since 1946. Detecting a metal whiskers (MWs) is often a challenging task because of their random growth nature and very small size (diameters can be less than 1 µm, lengths vary from 1µm to several millimeters). Many decades ago the industry introduced whisker mitigating Pb in the solders used to fabricate electric and electronic parts. In recent years, this changed because the European Union (EU) passed a legislation in 2006, called “Restriction of the use of Certain Hazardous Substances (RoHS) in Electrical and Electronic Equipment”, which requires a reduction and elimination of the use of Pb in technology. Thus, the issue of undesirable and unpredictable whiskers growth has returned and there is a renewed interest in the mechanisms of formation of these structures. None of the whisker growth models proposed to date are capable of answering consistently and universally why whisker grow in the first place and why Pb addition suppresses their growth. Understanding MW nucleation and growth mechanism are of significant interest to this project, since this would potentially allow the development of new accelerated-failure testing methods of electronic components to replace existing testing methods which are generally found to be unreliable. In particular, this research is intended to study the effects of electric fields on the whisker growth, which according to the recently developed electrostatic theory[1] of whisker growth, are of crucial importance. This theory proposes that the imperfections on metal surfaces can form small patches of net positive or negative electric charge leading to the formation of the anomalous electric field (E), which go (open full item for complete abstract)

Committee: Daniel Georgiev Dr. (Committee Chair); Vijay Devabhaktuni Dr. (Committee Member); Victor Karpov Dr. (Committee Member); Devinder Kaur Dr. (Committee Member); Anthony Johnson Dr. (Committee Member) Subjects: Aerospace Materials; Chemical Engineering; Condensed Matter Physics; Electrical Engineering; Engineering; Experiments; Materials Science; Metallurgy; Nanoscience; Nanotechnology; Physics; Plasma Physics; Solid State Physics; Theoretical Physics

Doctor of Philosophy, The Ohio State University, 2017, Public Policy and Management

This dissertation examined whether participation in US Defense Security Cooperation (DSC) programs leads to reductions in a regime's willingness to inflict political terror such as extrajudicial killing, torture, disappearances, and political imprisonment. Two objectives framed the research: first, to identify structural factors that give rise to political terror, and second, to assess the efficacy of non-kinetic US intervention policies in allied nations. Though DSC programs are widely studied, the programs have been primarily evaluated in output terms such as dollars (Foreign Military Sales), the number of foreign officers trained (International Military Education and Training), and the number and cost of engagement events (National Guard State Partnership Program; SPP). To advance knowledge on DSC programs in outcome terms, this research started by recreating the key components of Poe and Tate (1990, 1994) causal frameworks on personal integrity rights. The initial objectives were to confirm or refute predictor variable results and to determine if the Poe and Tate-derived Political Terror Scale (PTS) was an appropriate measure to evaluate the efficaciousness of DSC programs. Next, the research expanded to include both a 167-country global time-sensitive cross-sectional (TSCS) analysis and a 46-country regional TSCS analysis using the US Geographic Combatant Commander Areas of Responsibilities (AORs) as its country-by-country delineation. Data collection began by creating the Rebuilding Failed and Weak States Dataset (RFWS Dataset) which included extensive data on a myriad of variables theorized to influence political terror. The RFWS Dataset covered 20 years from 1993-2012 plus four years 1989-1992 for variable lag effects. The PTS and the Fund for Peace's Fragile States Index (FSI) were the dependent variables since they represent globally respected indices of political terror and human rights abuses. Results validated the extant literature's conclusions (open full item for complete abstract)

Committee: Trevor Brown (Committee Chair) Subjects: Military Studies; Public Administration; Public Policy

Doctor of Philosophy, University of Toledo, 2009, Biology (Ecology)

Under conditions of compromised immunity, certain pathogenic strains of staphylococci can cause severe infections in humans and animals. Of the ca. 31 species of staphylococci currently recognized, 15 are potentially pathogenic to humans. Resistance to a variety of antibiotics has given certain members of the staphylococci a prominent place among emerging and re-emerging pathogens. Staphylococcus spp are ubiquitously distributed in a variety of hosts, multiple routes of transmission between hosts and between hosts and their environment have contributed to the spread of staphylococci beyond the boundaries of health care facilities and into the community. Environmental and community reservoirs (e.g. shared surfaces and natural environment) of staphylococci, including S. aureus and coagulase-negative staphylococci CNS, have not been thoroughly identified. Furthermore, studies related to the contamination of surfaces (clinical or environmental) with staphylococci have historically focused on one or several species that were considered clinically important (e.g. methicillin-resistant S. aureus, MRSA). To address this void in our knowledge of an important group of potentially pathogenic bacteria, research was designed to: i- identify public surfaces that harbor antibiotic-resistant bacteria communities, including several members of the staphylococci, ii- show that mecA (an important genetic determinate that confers resistance to several popular, therapeutic antibiotics) is widely distributed in nonstaphylococcal pathogens inhabiting a secondary environment, and; iii- demonstrate a newly developed methodology that allows the simultaneous detection and species identification of most of the clinically important staphylococci, and apply the method to investigate the contamination of clinical surfaces with staphylococci. In the first study, multiplex-PCR techniques were developed to detect and identify staphylococci, including methicillin-resistant staphylococci, on com (open full item for complete abstract)

Committee: Von Sigler PhD (Advisor); Scott Heckathorn PhD (Committee Member); Gruden Cyndee PhD (Committee Member); Michael Weintraub PhD (Committee Member); Turco Ron PhD (Committee Member) Subjects: Microbiology

Doctor of Philosophy, The Ohio State University, 2010, Chemical Physics

Infrared spectra of individual micron-scale particles can be measured accurately and inexpensively by placing them in the holes of plasmonic nickel mesh. This thesis describes many aspects of modeling infrared spectra of particles and coating in or near the holes of nickel mesh using Finite-Difference-Time-Domain (FDTD) software. These aspects include: 1) Background information on surface plasmons and extraordinary transmission 2) Background information about modeling with FDTD systems. 3) Simple mesh models that predict plasmonic mesh spectra qualitatively. 4) More complex mesh models that take much longer but give quantitative results. 5) Important aspects about modeling peak splitting in plasmonic mesh. 6) Modeling plasmonic mesh with thin layers and coatings. 7) Modeling the spectra of individual particles on plasmonic mesh.

Committee: James Coe (Committee Chair); John Herbert (Committee Member); Ezekiel Johnston-Halperin (Committee Member); Jay Kandampully (Committee Member) Subjects: Chemistry; Condensed Matter Physics

Doctor of Philosophy, The Ohio State University, 2010, Public Health

Methicillin-resistant Staphylococcus aureus (MRSA) is a significant infectious disease concern in human and veterinary healthcare settings where airborne transmission is suspected. A better understanding of sampling methods used for airborne MRSA surveillance is fundamental for accurately evaluating and successfully controlling the threat. Accordingly, we conducted laboratory and field studies to evaluate methods and risk associated with airborne MRSA. In the laboratory, Methicillin-susceptible Staphylococcus aureus (MSSA) was used as a surrogate for MRSA. Using a laboratory environmental chamber, we systematically evaluated: 1) MSSA particle size distribution, 2) efficiency of two aerosol generating methods (6-jet Collison nebulizer and Bubbler), and 3) recovery and collection of MSSA using three air sampling methods (Gelatine Filter, single-stage Impactor, and Impinger). Generation efficiencies of MSSA were evaluated using the ratio of the number concentration of airborne culturable particles to total particles. Total particle concentrations were evaluated with an aerodynamic particle sizer (TSI, Inc.) and culturable particles were evaluated using standard methods. Differences in generation efficiency were evaluated using a two sample t-test. Sampler performance was evaluated by examining: 1) loss of MSSA spiked onto the sampler over time, and 2) side-by-side measured concentration differences of airborne MSSA collection across a 4-log range aerosolized from the generator reservoir. Sampler recovery and collection comparisons were made using paired t-tests. From these laboratory studies, a pilot-scale field investigation of airborne and surface Staphylococcus spp., was performed within a veterinary hospital during periods of no known clinical Staphylococcal infections. Based on the laboratory studies we observed the aerodynamic particle size of airborne S. aureus at 0.723-0.777 micrometers. The Bubbler (1.16 x 10-4 CFU/particle) was observed to be marginally more (open full item for complete abstract)

Committee: Timothy Buckley PhD (Advisor); Armando Hoet PhD (Committee Member); Michael Pennell PhD (Committee Member); Kurt Stevenson MD (Committee Member) Subjects: Occupational Safety; Public Health; Veterinary Services

Master of Science, The Ohio State University, 1972, Zoology

Committee: Theodore Bookhout (Advisor) Subjects:

Doctor of Philosophy, The Ohio State University, 2005, Plant Pathology

Phomopsis cane and leaf spot is a disease of grape ( Vitis spp.) caused by Phomopsis viticola(Sacc.). The fungus survives winter in grape cane tissues that were infected in previous years. In the spring, conidia are splashed by rain onto new growth where they infect the plant tissues. The fungus can infect many parts of the grape, including shoots, rachises, leaves, and fruits, and infection typically takes place when the tissues are immature. The disease is considered to be monocyclic. The control of the disease has usually been done by either selective pruning of diseased canes (reducing inoculum) or preventative spraying of protectant fungicides onto new tissues. To extend our understanding of the epidemiology and control the disease, studies were conducted to: 1) evaluate a disease warning system by applying fungicides and fungicide-adjuvant combinations based on predicted infection periods utilizing measured weather conditions; 2) determine efficacy of a dormant fungicide spray program for controlling the disease in its early stage of development (spring); 3) correlate commercial control practices and environmental conditions with disease incidence based on a state-wide survey of commercial vineyards; and 4) determine spatial pattern of the disease in small (within a vine) and large (among vines) spatial scales using a range of spatial analyses. With the warning system, control was often equal to that obtained with a 7-day calendar-based protectant program, but with fewer fungicide applications. However, fungicides and fungicide-adjuvant combinations used with the warning system did not show curative activity in a controlled-environment study. A dormant fungicide application provided consistent, yet only moderate, control of the disease; however, growers who applied a dormant application or spring protectants tended to have less disease incidence based on the results of the commercial survey. Analyses of spatial patterns revealed that the disease tended to aggr (open full item for complete abstract)

Committee: Laurence Madden (Advisor) Subjects: Agriculture, Plant Pathology

Master of Arts (MA), Ohio University, 2006, Geological Sciences (Arts and Sciences)

A remote sensing investigation was conducted in June 2000 in a mixed-oak forest undergoing successional changes at Black Rock Forest, NY. Leaf litter data was collected throughout the fall of 2000 to assess productivity at the site and to obtain species-specific leaf area(LAI SPP) data for Acer rubrum, Quercus prinus, and Quercus rubrum. There were two objectives in this investigation: to determine (1) whether spectral differences exist at branch-level between the oak and maple groups at this site, and (2) whether the remotely-sensed canopy-level classifications are able to produce estimates of canopy cover for red maple that reflect the forest composition identified with the LAI SPPinformation. Significant multispectral differences were identified for all groups at the branch-level. Canopy-level analyses were restricted to the 550 nm wavelength because of calibration issues with the imaging system. These images were processed using soft classification methods, and produced canopy cover maps of questionable accuracy.

Committee: James Lein (Advisor) Subjects:

Doctor of Philosophy, Case Western Reserve University, 2010, Pathology

Since the introduction of penicillin, β-lactam antibiotics have been the antimicrobial agent of choice for the treatment of many infections. Unfortunately, the efficacy of these life-saving antibiotics is significantly threatened by bacterial β-lactamase enzymes. To overcome β-lactamase-mediated resistance, β-lactamase inhibitors were introduced (clavulanate, sulbactam, and tazobactam). These inhibitors greatly enhance the efficacy of their partner β-lactams in the treatment of Gram-negative infections. However, selective pressure from excess antibiotic use accelerated the emergence of resistance to β-lactam/β-lactamase inhibitor combinations. Furthermore, the prevalence of clinically relevant β-lactamases that are intrinsically resistant to inhibition is rapidly increasing. There is an urgent need for effective inhibitors that can restore the activity of β-lactams. Here, we demonstrate that the Asn276Asp substitution confers resistance to clavulanate in the class A SHV β-lactamase. Unlike the Asn276Asp substitution in the related TEM enzyme, and inhibitor-resistant β-lactamases in general, the SHV variant maintains a high level of catalytic efficiency for penicillins. This “fine-tuning” of the inhibitor-resistant phenotype may represent a significant evolutionary advance, as the enzyme maintains a balance of desired catalytic properties. By probing Asn276 with selectively designed inhibitors, we explored how the configuration of the conserved β-lactam carboxylate impacts binding. Despite relative distance from the active site, this second-shell residue exerts important effects on enzyme-ligand interactions. Our work also addresses the class C β-lactamases from Acinetobacter spp. and Pseudomonas aeruginosa, pathogens of increasing clinical concern for which few effective therapeutic options remain. The currently available β-lactamase inhibitors are inactive against these enzymes, and thus development of “second-generation” agents is a priority. We first studied (open full item for complete abstract)

Committee: Robert A. Bonomo M.D. (Advisor); Shu G. Chen Ph.D. (Committee Chair); Focco van den Akker Ph.D. (Committee Member); Michael Harris Ph.D. (Committee Member); Marion Skalweit M.D., Ph.D. (Committee Member) Subjects: Biochemistry; Microbiology