Master of Science, University of Akron, 2025, Geology

Quartz and feldspars are the most common minerals in the continental crust ( >91 wt%). These minerals are very strong in the upper continental crust (depth < 12 km, T < 300°C) where they deform by brittle mechanisms, but quartz weakens significantly at greater depths as it begins to deform by crystal plastic mechanisms. Therefore, quartz is thought to control the strength of rocks in the mid-to-lower continental crust and its rheology is used to model the strength of the mid-to-lower continental crust. The flow laws used to determine quartz rheology are determined using data from deformation experiments performed on natural quartzites at T > 900°C. These natural quartzites contain small (< 1 vol%) amounts of muscovite and other minerals. Muscovite reacts with quartz to form melt at T > 800°C at the confining pressure commonly used in these experiments (Pc = 1.5 GPa), which indicates that these experiments likely contain small amounts of melt. I performed single-pressure and pressure-stepping deformation experiments on two natural quartzites, the Tana quartzite and the Arkansas novaculite, using a solid salt assembly in a Griggs apparatus at high temperature (T = 900°C) and strain rate (1.6 * 10-6 s -1 ). Pressure was varied to change the ƒ𝐻2𝑂 which affects the strength of quartzites. Single-pressure experiments were performed at Pc = 1000 MPa to 1600 MPa to duplicate previous experiments. iv Pressure-stepping experiments were performed in increasing or decreasing 200 MPa (Pc range = 1000 to 1600 MPa) steps to determine if there was a pathdependence to the quartzite strength. Strength of the Tana quartzite increased as a function of time at conditions in decreasing pressure-stepping experiments, while strength of Tana quartzite increased and decreased as a function of time at conditions in increasing pressure-stepping experiments; strength of the Arkansas novaculite decreased as a function of time at conditions in both (open full item for complete abstract)

Committee: Caleb Holyoke III (Advisor); John Senko (Committee Member); Molly Witter (Committee Member) Subjects: Geology

Doctor of Philosophy in Engineering, Cleveland State University, 2024, Washkewicz College of Engineering

Cell therapies derived from induced pluripotent stem cells iPSCs hold promise in a wide array of clinical areas due to their capacity to differentiate into various cell types. Among these, pancreatic iPSC derived β-cells for treating Type 1 diabetes. However, there are many challenges surrounding scaling iPSC production and their derivatives such as β- cells for clinical use. These challenges have been addressed by developing an optimized bioengineered process for expanding iPSCs and differentiating them into β-cells. Through comprehensive experimentation and mathematical modeling, this research optimizes iPSC production, maintenance, aggregation, and pancreatic differentiation process and protocol transfer into a 3D environment, by defining critical process parameters (CPPs) and critical quality attributes (CQAs) essential for clinical translation. The goal of this research work is to contribute to the clinical translation of iPSC- based therapies and specifically for Type 1 diabetes by leveraging multifactorial perturbation methodology and bioprocess understanding to generate a scale necessary for clinical treatments. The study has two main focuses. One is to optimize the cell medium needed for iPSC maintenance and aggregate stability utilizing a design of experiments (DoE) approach in PBS vertical wheel bioreactors. The second focus is on the specific differentiation of iPSCs into β-cells, employing an optimized HD-DoE protocol and designing it for scalability in a suspension environment implemented in vertical wheel bioreactors with process optimized parameters from seeding to banking. The iPSC expansion, maintenance and optimization in 100 ml vertical wheel bioreactors tested in a factorial design identifies combinational media additives that attain pluripotency, continuous growth, and aggregate stability. The three-stage suspension pancreatic differentiation protocol developed for β-cells, is compared to an adherent differentiation then it transitions into (open full item for complete abstract)

Committee: Michael Bukys (Advisor) Subjects: Biomedical Engineering; Biomedical Research; Chemical Engineering; Engineering

Doctor of Philosophy, The Ohio State University, 2022, Horticulture and Crop Science

Many Midwestern organic farmers in their focus on improving soil quality for crop production attempt to balance their soil's calcium (Ca) and magnesium (Mg) saturation levels by applying calcium-rich amendments. For most soils, this practice based on the base cation saturation ratio (BCSR) hypothesis, requires repeated applications of calcitic limestone and or gypsum to increase Ca to approximately 65% of a soil's saturation capacity and reduce Mg saturation to less than 20%. Expected and claimed benefits of this practice of soil balancing include improved soil structure, decreases in weed pressure, and increases in crop yield. We applied various Ca and Mg rich minerals in a corn-soybean-small grain rotation in two Ohio soils over several years. Our treatments were designed to contrast the effects of different Ca to Mg ratios on the weed community and on soil properties. Our research is the first to provide evidence that Ca:Mg ratios in the soil can reduce density of weed seeds found in the soil. At the silt loam soil, broadleaf and grass seedbank densities were on average about 25% and 40% lower after the second year of gypsum applications, respectively, across crops. Weed emergence for the same soil showed a similar response. At the clay loam soil, grass seedbank densities were on average about 40% higher after the third year of epsom application across crops. Our experimental design enabled us to also investigate the claim of soil balancing proponents and farmers that the increases in crop yield they experienced were due to higher Ca:Mg ratios rather than pH correction. We examined crop yield in response to both pH and Ca and Mg saturation levels over 6 years and concluded that balancing the soil Ca and Mg levels did not impact corn or soybean yields but managing soil acidity did. Our results confirm that correcting excess acidity remains the fundamental reason to apply limestone as a tool to improve crop yields. Previously reported research from our project had (open full item for complete abstract)

Committee: Douglas Doohan (Advisor); Christine Sprunger (Committee Member); John Cardina (Committee Member); Steve Culman (Committee Member) Subjects: Agriculture; Agronomy; Soil Sciences

Master of Science (M.S.), University of Dayton, 2022, Chemistry

Certain molecules (photochromic compounds), when exposed to the light of a specific wavelength, undergo a reversible “isomeric” transformation which leads to reversible changes in some physicochemical properties. Azobenzene derivatives are an example of a photochromic compound that undergoes “cis-trans isomerization” upon irradiation with UV–visible light. Azobenzene derivatives have been previously found to form dynamic photo-responsive supramolecular aggregates. This research aims to further investigate the properties of azobenzene derivatives, and an in-depth understanding of how they form, if at all, dynamic photo-switching aggregates. To evaluate, and study the properties of these molecules, experiments such as solubility, irradiation, and pH experiments were conducted.

Committee: Angela Mammana (Advisor); Vladimir Benin (Committee Member); Justin Biffinger (Committee Member) Subjects: Chemistry

Master of Science in Engineering, University of Akron, 2022, Civil Engineering

The main goal of this study is to help the Ohio department of transportation (ODOT) in determining areas that may have future fine or coarse aggregate supply shortfalls, estimate the economic impact of those shortfalls, and recommend appropriate policy changes to deal with these shortfalls in the aggregate supply. The state of Ohio was divided into different study regions based on aggregate quality and availability, data was obtained from ODOT and the Ohio Department of National Resources to help estimate the amounts of aggregates produced and consumed in each region. Furthermore, information for individual mines were gathered from their representatives to help estimate the local aggregate reserves in each study region, also, different models were used in this study to forecast the number of years needed to deplete these reserves. Furthermore, this study discusses information that was collected from several aggregate industry representatives about barriers to expanding existing aggregate mines or permitting new ones. Furthermore, zoning laws related to the mining industry in Ohio are examined in this study. The study also proves that the geological deposits of the limestone and sand and gravel aggregate supplies are not uniformly distributed across the state, for example limestone reserves are limited in the eastern regions, whereas sand and gravel reserves are limited in the southern and northwestern regions. This will cause an increase in the demand for imported aggregates from other regions to cover the needs for good quality aggregates or use the locally availably lower quality aggregates. The study also recognizes areas within the state that are liable to be depleted from available aggregates in the future, this may be caused by the fact that the region in question already has low reserves of that specific aggregate type or caused by the high consumption rate of aggregates in that region. For example, currently, the central region has moderate amounts of re (open full item for complete abstract)

Committee: Ala Abbas (Advisor); Nariman Mahabadi (Committee Member); Ping Yi (Committee Member) Subjects: Civil Engineering

Master of Science (M.S.), University of Dayton, 2020, Chemistry

In the area of photochemistry, many molecules can undergo photoisomerization. Within these photoswitches is a family of molecules derived from azobenzene, which can form what are called supramolecular aggregates. When these molecules are in the presence of one another, they can form large structures. In addition to this, such molecules may also be able to maintain their ability to photoswitch while in a supramolecular structure. These supramolecular photoswitching aggregates have been used in many different applications including hydrogels and sol-gels, and the effort of cataloging and characterization of these molecules is a novel endeavor. Previous testing has concluded that ADA (Azobenzene-4,4'-dicarboxylic acid) and M0423 (4-Dimethylaminoazobenzene4'-carboxylic acid) show aggregation properties as well as photoswitching properties when paired together. When by themselves they show remarkable self-aggregation, however, they both do not show photoswitching properties. ADA shows photoswitching properties while M0423 does not. This data was confirmed through additional tests. The addition of the molecule A1598 (Azobenzene-3,3'-dicarboxylic acid) shows shocking similarities in aggregation to ADA in addition to possessing its own unique attributes. A1598 was confirmed to have formed aggregates with itself and M0423. These tests also confirmed a preferred pH and mixing ratio for the ADA and A1598-M0423 aggregate as well as assessing their photoswitching capabilities and aggregation under the stresses of photoswitching. Showing that both molecules when aggregated, regardless of the high degree of order displayed in the spectra, locked up. This prevented further photoswitching from occurring. This research shows that there is still more that can be learned from these molecules and similar azobenzene derivatives with respect to photoswitching aggregates.

Committee: Angela Mammana Ph.D. (Advisor); Vladimir Benin Ph.D. (Committee Member); Mark Masthay Ph.D. (Committee Member) Subjects: Chemistry; Organic Chemistry

Doctor of Philosophy (PhD), University of Toledo, 2019, Biomedical Sciences (Medical Microbiology and Immunology)

Cancer patients are known to be at high risk for thrombosis, a leading cause of death among cancer patients. Cancer patients are also at increased risk of developing recurrent thrombosis or severe bleeding as a result of anticoagulation therapy to treat cancer-associated thrombosis. Platelet-leukocyte aggregates (PLAs) are associated with increased thrombosis risk, but it remains unclear how PLA formation may influence thrombosis in the context of cancer. We tested the hypothesis that lung cancer patient platelets differ from healthy volunteers. Increased platelet counts can be a significant predictor of history of thrombosis in lung cancer patients. Lung cancer patient platelets expressed more P-selectin, a marker of activation, than healthy volunteers did (mean fluorescence intensity of P-selectin 29.12 and 11.69 units, respectively). We compared PLA formation in lung cancer patients compared to healthy volunteers. Lung cancer patients had significantly more CD4+ platelet-T cell aggregates (PTCAs) than healthy controls (36.84% of total CD4+ T cells vs. 19.01%, respectively). The detection limit of >22.43% CD4+ PTCAs was 76.92% sensitive and 72.55% specific for lung cancer. Lung cancer patients had significantly more CD8+ PTCAs than healthy controls (48.41% of total CD8+ T cells vs. 28.77%, respectively), and the detection limit of >35.24% CD8+ PTCAs was 75.00% sensitive and 73.08% specific for lung cancer. T cell-bound platelets were significantly more activated in lung cancer patients compared to healthy controls. Platelets in CD4+ PTCAs expressed MFI of 113.7U in lung cancer patients and 64.67U in healthy volunteers, and the detection limit of >55.15U was 62.22% sensitive and 69.57% specific for lung cancer. Platelets in CD8+ PTCAs expressed MFI of 159.7U in lung cancer patients and 90.35U in healthy volunteers, and the detection limit of >79.95U was 63.04% sensitive and 64.44% specific for lung cancer. We further explored the role of past history of thro (open full item for complete abstract)

Committee: Randall Worth PhD (Committee Chair); R. Mark Wooten PhD (Committee Chair); James Willey MD (Committee Member); Kathryn Eisenmann PhD (Committee Member); Saurabh Chattopadhyay PhD (Committee Member) Subjects: Biomedical Research; Cellular Biology; Immunology; Medicine; Oncology

Master of Science, University of Akron, 2018, Civil Engineering

Glass is one of the principal waste products generated in the US. The use of these glass cullet in the construction of shoulder section could reduce the quantity of waste glasses that goes to the landfill. Certain type of cementing agent is required to bind these glass particles in shoulder. Enzyme induced carbonate precipitation (EICP) has shown early promise as a viable and sustainable ground improvement method. Water based EICP leads to faster infiltration of cementation solution due to high permeability, thus limiting the amount of available reaction substances to produce CaCO3 precipitate at desired locations. This problem may be solved to some extent by the use of high viscosity polymer as a carrier of cementation solution in place of water. Laboratory tests performed on the recycled glass cullet showed the possibility of using them in the construction of shoulder section to prevent erosion. Moreover, a series of laboratory experiments performed showed that EICP worked well on the Ottawa sand but did not work well on recycled glass cullet. However, it was successful on the samples containing mixture of glass particles and Ottawa sand. The samples consisting up to 20% of recycled glass in the mixture were brittle and strong. The results of UCS testing showed the compressive strength of the intact sample decreases with increase in amount of recycled glass in the mixture. The pull out test carried out on the glass surface showed the possibility of application of EICP on the surface treated glass particles. SEM, XRD and TGA results on the samples treated with polymer modified EICP verify the presence of CaCO3 and the strength of the samples were tested at different moisture contents. The treated sand columns were organic-inorganic composites with sand cemented by a CaCO3-PVA mixture. Unlike low molecular weight PVA, medium molecular weight PVA forms complex matrix with the CaCO3 precipitate which does not dissolve in water at room temperature. The unconfine (open full item for complete abstract)

Committee: Junliang Tao PhD (Advisor); Zhe Luo PhD (Committee Member); Qixin Zhou PhD (Committee Member) Subjects: Civil Engineering

Master of Science, University of Akron, 2015, Civil Engineering

Literature review of several research projects have widely endorsed Spray Injection Patching method as a cost effective and durable pothole repair technique. While these studies provide detailed information related to different states, few researches have been made in Ohio to find out best material combinations to address compatibility issues of different aggregates with asphalt emulsions and best procedure to a long lasting spray injection patch. This study focusses on laboratory testing (compatibility, demulsibility and sensitivity analysis) accompanied with installation of pothole patches from spray injection patching method and its monthly evaluation. Laboratory test for compatibility evaluation was done as described in section 16 of AASHTO T 59-09 with some modifications in which fifteen different aggregates were mixed with seven different asphalt emulsions and in the demulsibility evaluation, the same aggregates were mixed with an asphalt emulsion of six different demulsibility values. For sensitivity test, aggregates stored at room, low and freezing temperature with varying moisture and dust contents were mixed with one asphalt emulsion according to section 16 of AASHTO T 59-09. During these tests, percentage coatings of the mixture, time to start turn black, balling etc. were noted. After laboratory tests, 8 different test sites were chosen with natural cracks and potholes to be durapatched with three aggregates and five asphalt emulsion. Unlike several other studies, no artificial potholes were created for this project. Each site was divided into 40 feet sections and size and dimension of potholes before durapatching were noted. Each section of each site was given a rating based on its condition in the months following installation. These findings were analyzed to find the durability of the spray injection patches with respect to material combinations and climatic conditions. It was observed that cationic emulsion worked better with gravels and anio (open full item for complete abstract)

Committee: Ala R. Abbas (Advisor) Subjects: Civil Engineering

Master of Science, The Ohio State University, 2014, Geological Sciences

Surface mine reclamation results in the removal and redistribution of soil materials, which has a profound effect on many soil properties. The Surface Mine Control and Reclamation Act (SMCRA) of 1977 was enacted by Congress to mitigate some of the negative consequences of surface mining. The goal of this research was to understand the impact of SMCRA on the development of permeability within the soil, as it relates to soil aggregate formation in the development of soil structure. To determine this, field saturated hydraulic conductivity (Kfs) measurements were made in three areas, one area reclaimed prior to SMCRA, one area reclaimed under the guidelines set forth by SMCRA, and one area that had not been mined. Soil samples were also gathered in order to assess whether soil aggregation was proceeding normally, or whether it was disrupted in any of the three areas. A wet sieving process was used to separate soil the soil aggregates into three size fractions. Organic material that was not contained within the soil aggregates was removed by physical separation, and the soil aggregates within each size fraction were analyzed for d13C and C/N. These data were then used to ascertain whether aggregation was proceeding normally. It was hypothesized that if aggregation was proceeding according to patterns established I the literature that the soil would be developing structure, and would thus have a higher measured Kfs. The aggregate dynamics study demonstrated that the unmined reference site was developing according to expected patterns (normally), and that the post-SMCRA reclaimed area was developing more normally than the pre-SMCRA area. The unmined area did not have the highest Kfs values, but the post-SMCRA site had a higher average Kfs than the pre-SMCRA site, based on limited data.

Committee: Anne Carey Dr. (Advisor); William Lyons Dr. (Committee Member); Michael Durand Dr. (Committee Member) Subjects: Earth; Environmental Geology; Environmental Science; Geology

Doctor of Philosophy (PhD), University of Toledo, 2014, College of Medicine

Patients with inflammatory cardiovascular disease have an increased number of circulating activated platelets and platelet-leukocyte aggregates (PLAs), both of which play a central role in the initiation and progression of disease. Activated platelets can activate the complement system on their surface, with potential consequences in vascular inflammation and thrombosis. Properdin, a positive regulator of the alternative pathway (AP) of complement, is produced mainly by stimulated leukocytes. The mechanisms by which properdin participates in complement activation on platelets and in PLA formation remain unknown. We have shown that the physiological forms of human properdin bind directly to activated, but not resting, platelets. The binding of properdin promotes AP complement activation on activated platelets, as measured by C3b and C9 deposition on their surface, by forming novel C3 convertases on the platelet [C3(H2O),Bb]. Removal of surface proteins by treating platelets with a low dose of proteinase K, leads to reduced properdin binding to activated platelets. On the other hand, chondroitin sulfate-A (a glycosaminoglycan that is released by platelets upon activation) increases the binding of properdin to activated platelets by ~4 fold. These results suggest that interaction of properdin with activated platelets may depend on a protein receptor as well as glycosaminoglycans (i.e. proteoglycans). We have also determined that properdin released by PMA-stimulated neutrophils binds to activated platelets. Since activated neutrophils and platelets directly interact with one another in pro-inflammatory microenvironments, the fresh properdin produced by neutrophils would be available to platelets at high concentrations. Using ex-vivo whole blood assays, we show that properdin leads to an increase in PLA formation in TRAP (thrombin receptor activating peptide)-stimulated whole blood and inhibition of properdin leads to decrease in PLA formation. Our data also show that pr (open full item for complete abstract)

Committee: Viviana Ferreira D.V.M., Ph.D. (Advisor); Stanislaw Stepkowski D.V.M., Ph.D. (Committee Member); Mark Wooten Ph.D. (Committee Member); Kevin Pan M.D., Ph.D. (Committee Member); Guillermo Vazquez Ph.D. (Committee Member) Subjects: Biology; Biomedical Research; Immunology

PhD, University of Cincinnati, 0, Engineering and Applied Science: Materials Science

A recent method to quantify molecular topologies of various materials using small-angle scattering has been used to quantify fractal systems like polymer solutions and ramified aggregate structures. Small angle x-ray and neutron scattering has been used to characterize ceramic aggregates and polymer systems respectively. Ramified aggregates are formed in many dynamic processes such as in flames. Such structures are disordered and present a challenge to quantification. The topological quantification of such nanostructured materials is important to understand their growth processes. Small-angle X-ray scattering (SAXS) is widely used to characterize such nanoparticle aggregates. The details in ceramic aggregates like branch fraction, number of segments in an aggregate and the short circuit path, coordination number and the number of end groups are extracted. In order to explicitly determine the nature of chain scaling, related to topology or solvent quality, as well as to quantifying the thermodynamic interactions, the coupling of the unified scattering function with the Random Phase Approximation (RPA) equation and inter-arm interactions based on Benoit's approach is proposed to enable analytical quantification of these effects using a scaling model. The scattering function places structural constraints from the model to limit the Unified Fit Function for hierarchal scattering. A detailed topological quantification of star polymer systems has been able to describe both, good and theta solvent conditions along with effect of functionalities, as well as resolve deviations in chain conformations due to steric interactions between star arms. An investigation on different solvent conditions for 6-arm polyurethane star polymers was done and the scaling parameters were extrapolation to zero entropy collapsed and extended chain states to understand the possible topological variations in the system. Polyisoprene star polymers under good solvent condition were used (open full item for complete abstract)

Committee: Gregory Beaucage Ph.D. (Committee Chair); Jude Iroh Ph.D. (Committee Member); Vikram Kuppa Ph.D. (Committee Member); Vesselin Shanov Ph.D. (Committee Member) Subjects: Materials Science

MS, University of Cincinnati, 2009, Engineering : Civil Engineering

This project examines whether the addition of microsilica or the use of aggregates with maximum size above 1.5 in., in concrete mixes prepared by the Ohio Department of Transportation (ODOT) for bridge decks and highway pavements, can have adverse effects on the durability properties of such structures. The behavior of several series of concrete specimens has been monitored over a period exceeding a year, and measurements of shrinkage, creep, abrasion, rapid chloride permeability, and freeze/thaw resistance have been recorded. Such data are evaluated to determine if altering the standard ODOT concrete mix design on either end of the gradation spectrum can indeed lower the cement content and increase its cost effectiveness and efficiency. It was found that different coarse aggregate gradations did not impact significantly the environmental properties of concrete examined. Variability issues related to the testing protocols themselves confounded the differences observed. These results indicate that larger sized coarse aggregates can be used for pavements and highway structures without significantly compromising the environmental properties of the concrete, and afford concrete producers more flexibility in creating cost-effective and cement-efficient mixes. It was found earlier in State Job No. 14800(0) that the compressive and flexural strengths of abused microsilica did not differ much from that of densified microsilica. This conclusion is brought into question, at least in the case of abused microsilica, by the rapid chloride permeability results obtained. Nonetheless, all values obtained are within the limits termed as low or moderate by the prevailing specifications.

Committee: Anastasios M. Ioannides PhD (Committee Chair); Richard A. Miller PhD (Committee Member); Mark Bowers PhD (Committee Member); Michael Baseheart PhD (Committee Member) Subjects: Civil Engineering

PhD, University of Cincinnati, 2007, Engineering : Materials Science

The phenomenon of structural branching is ubiquitous in a wide array of materials such as polymers, ceramic aggregates, networks and gels. These materials with structural branching are a unique class of disordered materials and often display complex architectures. Branching has a strong influence over the structure-property relationships of these materials. Despite the generic importance across a wide spectrum of materials, our physical understanding of the scientific nature of branching and the analytic description and quantification of branching is at an early stage, though many decades of effort have been made. For polymers, branching is conventionally characterized by hydrodynamic radius (size exclusion chromatography, SEC, rheology) or by counting branch sites (nuclear magnetic resonance spectroscopy, NMR). SEC and rheology are, at best, qualitative; and quantitative characterization techniques like NMR and transmission electron microscopy (TEM) (for ceramic nanoparticulate aggregates) have limitations in providing routine quantification. Effective structure characterization, though an important step in understanding these materials, remains elusive. For ceramic aggregates, theoretical work has dominated and only a few publications on analytic studies exist to support theory. A new generic scaling model is proposed in Chapter I, which encompasses the critical structural features associated with these complex architectures. The central theme of this work is the application of this model to describe a variety of disordered structures like aggregated nano-particulates, long chain branched polymers like polyethylene, hyperbranched polymers, multi-arm star polymers, and cyclic macromolecules. The application of the proposed model to these materials results in a number of fundamental structural parameters, like the mass-fractal dimension, df, the minimum path dimension, dmin, connectivity dimension, c, and the mole fraction branch content, φbr. These dimensions refl (open full item for complete abstract)

Committee: Dr. Gregory Beaucage (Advisor) Subjects: Engineering, Materials Science

PhD, University of Cincinnati, 2004, Engineering : Materials Science

Flame technology is an extremely effective method to synthesize nano-particles of ceramic oxides. The single-step chemistry, the ability to control shape and size and to produce millions of tons of nano-powders per annum with relative ease have made it popular with industry. Although this process primarily focused on oxides of silicon and titanium, it has now been adopted for manufacture of several other oxides of bismuth, vanadium, aluminum, iron, germanium and zirconium. There has been extraordinary progress in the application of flame burner to synthesize newer oxides having a wide range of particle size, polydispersity, composition and aggregation. But the fundamentals behind the mechanisms for particle formation and growth are still not well understood. Due to the extremely fast reaction rates, high temperatures and low concentrations associated with this process, it is difficult to accurately observe the formation of nuclei and their growth to aggregated nano-particles. Entire particle growth from inception to aggregation takes place in a few milliseconds! Light scattering and thermophoretic sampling have been used extensively to study such flames. But light scattering suffers from the brightness of the flame and the limitation on the size-range it can probe. It can only detect aggregates, and information about primary particles needs to be obtained by thermophoretic sampling. However thermophoretic sampling is an intrusive technique and sample collection in the flame involves disturbance of flow of the gases and the particles in the flame. It is necessary to find a single non-intrusive technique that can yield complete information for the flame and detect the rapid growth. In-situ small angle x-ray scattering (iSAXS), which utilizes high energy x-rays from synchrotron sources fits such a role perfectly. iSAXS of particles in the flame provides full information from nano-scale to micron-scale and about the evolution of particles and their morphology. Experimen (open full item for complete abstract)

Committee: Dr. Gregory Beaucage (Advisor) Subjects: Engineering, Materials Science

MS, University of Cincinnati, 2001, Engineering : Materials Science

Aggregation of organic pigments was studied by small and ultra-small angle x-ray scattering. The aggregation of organic pigments and the implications for optical properties has not been previously reported in the literature, although extensive literature of this type exists for inorganic pigments such as titania. The pigments were also inspected for primary particle-size by electron microscopy and aggregate size by light scattering. The pigments were examined as dry powders as well as after embedding in polymer matrices. All the pigments exhibited mass-fractal behavior when mixed into various polymers. Some pigments exhibited mass-fractal behavior even in powder form. The scattering patterns reflected differences in mass fractal dimension and particle size. The mass fractal dimension and the size of the aggregates in the polymer depend on the chemical nature of the pigment, the size and strength of the primary particle, the surface characteristics of the pigment and the interaction between the pigment and the polymer. The size and mass fractal dimension of the aggregate shows a clear dependence on the type of polymer used. A relation between the aggregate size and optimal optical properties is proposed here. Aggregates having size between 1 to 2 microns show best optical properties. It is proposed that the pigment aggregate growth needs to be controlled during processing to have good optical performance of the pigment. The processes of aggregation were examined for these pigments. Most of the pigments formed aggregates by a reaction limited aggregation process, except two pigments, which exhibited diffusion limited aggregation.

Committee: Dr. Gregory Beaucage (Advisor) Subjects:

Master of Science, The Ohio State University, 2009, Natural Resources

Abrupt climate change (ACC) is an unprecedented global threat. Cost effective strategies to mitigate ACC include offsetting anthropogenic emissions through terrestrial carbon (C) sequestration. Cultivated tropical soils may contain 40 % less soil organic carbon (SOC) than their potential capacity. Consequently, the conversion into appropriate land use and management practices could increase the SOC pool and mitigate ACC. The identification of appropriate soils and land use options for establishment of terrestrial C offsets necessitate establishing what proportion of the total C pool is securely stable within the soil aggregates and adsorbed to the silt and clay particles of the soil. A field study was designed to understand mechanisms of C sequestration in soils of the Neotropics and their capacity to mitigate ACC under different management schemes. This study focuses on characterizing the SOC pool up to 1-m depth in 12 land uses, distributed in 3 contrasting ecoregions of Costa Rica. Specific objectives were to: (i) to determine the effect of land use on SOC pool, (ii) to establish the role of climatic parameters on SOC pool and, (iii) to establish the role of primary and secondary soil particles on the physical protection of SOC. The hypothesis tested was that SOC pool is significantly influenced by climate and land use, and its stability is strongly dependent on the physical protection provided by soil aggregates and primary particles. Results show that the mean SOC concentration was higher in the order Montane > Pacific Dry > Atlantic Moist ecoregion. The total SOC pool ranged from 114 – 150 Mg C ha-1 in the Atlantic Moist ecoregion, 76 – 165 Mg C ha-1 in the Pacific Dry ecoregion and 166 – 246 Mg C ha-1 in the Montane ecoregion. The estimated C sink capacity was of 18.1 - 36.7 Mg C ha-1, 14.1 – 88.6 Mg C ha-1 and 9.4 – 80.7 Mg C ha-1 in the Atlantic, Pacific and Montane ecoregions, respectively. The SOC was significantly correlated to bulk density, field mois (open full item for complete abstract)

Committee: Rattan Lal (Advisor); Frank Calhoun (Committee Member); Norman Fausey (Committee Member) Subjects: Agriculture; Environmental Science; Soil Sciences

Master of Science, The Ohio State University, 2005, Environmental Science

The current U.S. wetland mitigation policy of “no-net-loss” requires that a new wetland be created to replace any natural wetland destroyed under development pressures. The purpose of this study was to evaluate the ability of created wetlands to accumulate carbon and to mitigate the carbon-mediated functions occurring in natural wetlands. Soil physical properties were analyzed as potential inhibitors of carbon accumulation in the created wetlands. An exponential model was then used to estimate the time for created wetlands to accumulate that carbon found in natural wetlands.Five created (ages 3-8 years) and four natural freshwater marsh wetlands in central Ohio, USA were selected for this study. Nine to fifteen soil cores were collected at each site and analyzed for soil organic carbon (SOC), mineralizable soil carbon, water-stable aggregates (WSA), particle-size fractions and bulk density. Peak-standing aboveground plant biomass was harvested. Created wetlands contained less plant biomass, less SOC and less mineralizable carbon than natural wetlands (MRPP, T=-11.6, p< 0.007). For the soil physical properties, created wetlands contained less macroaggregates, more microaggregates, more silt-clay, and had higher bulk density than natural wetlands (MRPP, T=-4.16, p=0.007). The carbon parameters and soil physical properties were found to be correlated by RDA, carbon content was positively correlated with macroaggregate content and negatively correlated with microaggregate content, silt-clay fraction, and bulk density. A fit of the SOC data to an exponential model indicated that a newly created wetland would require 300 years to sequester the amount of SOC contained in a natural wetland. At this rate of carbon accumulation, a mitigation ratio of 2.6:1 (area) would be necessary for successful mitigation over a fifty-year time period. Other models were found to fit the data equally well, however, but provided different estimates to equilibrium (range of 70 to 12,000 years (open full item for complete abstract)

Committee: Virginie Bouchard PhD (Advisor); Richard Dick PhD (Committee Member); Siobhan Fennessy PhD (Committee Member); Rattan Lal PhD (Committee Member) Subjects: Ecology; Soil Sciences

PHD, Kent State University, 2009, College of Arts and Sciences / Department of Physics

The discovery of thermotropic biaxial nematic phase in bent-core mesogens, have engendered interest in these systems. Also, it undergoes optical switching about 100 times faster than conventional uniaxial nematic liquid crystal. Azo-substituted bent-core compounds, A131 and A103, were investigated as both offer an opportunity to observe their structures and phase transitions from the uniaxial nematic (Nu) to biaxial nematic (Nb) phase and from Nb to the underlying smectic-C (SmC) phase. Plank-like molecular systems are also expected to form Nb phase. Chromonic liquid crystals formed by aqueous solutions of plank-like dye molecules are interesting for their unique self-assembly and structural evolution. They have applications in optical element, coloring in food and textiles, and etc. Both systems were investigated with synchrotron x-ray scattering, polarizing optical microscopy, and differential scanning calorimetry. Temperature dependence of d-spacing and positional order correlations along the director clearly mark the phase boundaries where Nu-Nb transition was approximately 27o below the clearing point. Positional order correlation length of A131 increased from 1.5 in Nu to 3.3 molecular lengths in Nb phase, before it jumps by a factor of at least 5 in SmC phase. The lack of large discontinuous changes in the structural parameters and the subtle signatures in heat capacity establish the second order nature of Nu-Nb and Nb-SmC phase transitions. The chromonic system investigation results provide quantitative information of structural properties in nematic and columnar mesophases. We studied water solutions of (achiral) sunset yellow dye and (chiral and achiral) dihydrochloride salts of perylenebis-dicarboxydiimide. Positional order correlation lengths' measurements, parallel and perpendicular to the aggregate axis, revealed that they increase with concentration and decrease with temperature. Temperature dependence of correlation lengths yielded the scission en (open full item for complete abstract)

Committee: Satyendra Kumar Prof. (Advisor); David Allender Prof. (Committee Member); Elizabeth Mann Prof. (Committee Member); Arne Gericke Prof. (Committee Member); Oleg Lavrentovich Prof. (Committee Member) Subjects: Physics

Master of Science in Civil Engineering, Cleveland State University, 2008, Fenn College of Engineering

Steel slag is an industrial byproduct obtained from the steel manufacturing industry. It is produced in large quantities during the steel-making operations which utilize Electric Arc Furnaces (EAF). Steel slag can also be produced by smelting iron ore in the Basic Oxygen Furnace (BOF). Steel slag can be used in the construction industry as aggregates in concrete by replacing natural aggregates. Natural aggregates are becoming increasingly scarce and their production and shipment is becoming more difficult. Steel slag is currently used as aggregate in hot mix asphalt surface applications, but there is a need for some additional work to determine the feasibility of utilizing this industrial by-product more wisely as a replacement for both fine and coarse aggregates in a conventional concrete mixture. Most of the volume of concrete is aggregates. Replacing all or some portion of natural aggregates with steel slag would lead to considerable environmental benefits. Most of the natural aggregates in the state of Ohio are shipped in from out of the state, whereas large steel slag deposits are locally available. The primary aim of this research was to evaluate the durability of concrete made with steel slag aggregates. This research has shown that replacing some percentage of natural aggregates by steel slag aggregates causes negligible degradation in strength. It is shown that as the amount of steel slag is increased beyond 75%; the workability of the concrete mixture became an important issue which eventually requires larger amounts of water reducing admixtures to achieve a minimum slump. The results showed that replacing about 50 to 75% of steel slag aggregates by volume for natural aggregates will not do any harm to concrete and also it will not have any adverse effects on the strength and durability.

Committee: Norbert Delatte PhD (Committee Chair); Paul Bosela PhD (Committee Member); Lutful Khan PhD (Other) Subjects: Civil Engineering