Doctor of Philosophy (PhD), Ohio University, 2024, Chemical Engineering (Engineering and Technology)

Oil and gas transmission pipelines are frequently prone to internal corrosion in field environments. Use of organic corrosion inhibitors is an economical and effective way to combat this problem. Their typically amphiphilic inhibitor molecules provide protection by adsorption on the metal surface. Therefore, understanding and quantifying adsorption phenomena has significance for prediction of corrosion inhibition performance of a particular compound. In this dissertation research, a quartz crystal microbalance with dissipation monitoring (QCM-D) was the primary tool used to investigate the adsorption of two corrosion inhibitor model compounds on a noble gold substrate. The research reported herein shows how QCM-D can be used effectively to gain insights about the properties of the adsorbed layer, quantify adsorption/desorption kinetics, make predictions on the possible adsorbed layer configurations, and investigate the influence of inhibitor molecular structure on adsorption phenomena. Since real scenarios involve an actively corroding substrate, a classical oscillatory circuit-based quartz crystal microbalance (QCM) was also used to probe the metal-solution interface for a corroding and corrosion product forming experimental system; this facilitated deciphering the various reaction steps involved. The QCM-D findings in the present research indicate that the geometric surface coverage was less than 100% even for inhibitor concentrations above the surface saturation concentrations. This can help in answering a historical question in corrosion inhibition research about non-zero corrosion rates at inhibitor concentrations corresponding to maximum inhibition. Furthermore, the kinetic adsorption/desorption constants were estimated from the adsorption curves and verified successfully by predicting desorption behavior. This is of great significance, as this methodology can be further extended to study corrosion inhibition and its persistency. Furthermore, this serves as (open full item for complete abstract)

Committee: Srdjan Nešić (Advisor) Subjects: Chemical Engineering

Master of Science (MS), Bowling Green State University, 2012, Geology

Quartz cement formed during diagenesis is the principle cause of porosity and permeability reduction in sandstones and therefore greatly affects reservoir quality. Predictive quartz cement models have provided a basic ability to estimate reservoir quality for quartz-rich rocks under ideal diagenetic conditions. However, examination of more complex, specific diagenetic environments is required to improve the accuracy of predictive models applied to unconventional hydrocarbon reservoirs. Our experimental and numerical approach to this problem has examined quartz cementation processes by: 1) assessing the feasibility of relatively low temperature hydrothermal flow-through experiments for investigating silica dissolution, transport, and precipitation processes during diagenesis in active fluid flow environments, and 2) to assessing the effect of grain size and sorting on the rate of quartz cementation and corresponding pore space evolution in sandstones under static hydrothermal conditions. Hydrothermal flow-through results indicate that small amounts of new quartz cement can be generated in less than 10 days at relatively low temperatures when compared to previous experimental work. Results obtained from static hydrothermal experiments indicate that grain size and sorting effect both the rate of quartz cementation in our experiments and corresponding pore space evolution. The surface area normalized rate is observed to decrease more rapidly in fine grain size experiments when compared to coarse grain size experiments. Additionally, pore space analysis of both experimental and modeled results indicates that while all grain size fractions rapidly converge on similar total porosity values the 2D connectivity of porosity varies markedly as a function of grain size and sorting.

Committee: Farver John PhD (Committee Chair); Onasch Charles PhD (Committee Co-Chair); Panter Kurt PhD (Committee Member) Subjects: Geology

Master of Arts (MA), Bowling Green State University, 2005, Geology

Fluids, and water in particular, play an integral role in deformation within the Earth's crust over a wide range of physical conditions. At low temperatures (<150°C), the effect of water is dominantly mechanical, largely through the effects of pore fluid pressure. At higher temperatures (>300°C), water-related chemical processes, such as diffusive mass transfer, advective mass transfer, and hydrolytic weakening dominate. In the transition between high and low temperature regimes, both mechanical and chemical processes operate and interact in complex ways. The Cove fault zone in south central Pennsylvania contains several map-scale blocks of quartz arenite, which display a wide range of brittle and ductile microstructures. Abundant evidence of fluids is present from map- to lattice-scales, including quartz precipitated in microveins, fluid inclusion planes, and zones of cataclasis, and the removal of quartz along dissolution surfaces. Three different aqueous fluids were identified based on the cathodoluminescence color of quartz precipitated by that fluid, and the homogenization (T h ), last ice melting temperatures (T m ), and salt species from aqueous, two-phase fluid inclusions. Fourier Transform Infrared (FTIR) spectroscopy data indicate that a large amount of water has become incorporated in the lattice of deformed detrital grains, especially those in the proximity of fluid conduits (e.g., microveins). The fluids, based on the oxygen isotopic composition of the quartz precipitated, appear to be derived from basinal brines or metamorphic fluids that were probably driven northwestward along regional aquifers and fault zones. The microstructures in the Cove fault zone indicate that water was important in controlling the operative deformation mechanisms. Although brittle deformation is prevalent, a significant amount of ductile deformation is present. The formation of ductile microstructures at temperatures of less than 250° C is attributed to the presence of water (open full item for complete abstract)

Committee: Charles Onasch (Advisor) Subjects: Geology

Master of Science, The Ohio State University, 1920, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, University of Akron, 2023, Geology

Within the mid to lower continental crust distributed ductile thinning occurs, in orogens that form mountains like the Himalayas and Appalachia, due to a weak middle to lower crust that deforms laterally in response to loading of a thickened, cold upper crust. This thinning destabilizes large orogens and causes the exhumation of hot and weak rock from the mid to lower crust that begins to partially melt. This melting further weakens the rocks and may affect the deformation mechanisms operating in the crust. Melting has been seen to have impacts on the deformation mechanisms and resulting lattice preferred orientations (LPO) that form in olivine-basalt aggregates (Holtzman et al., 2003). To investigate the effects of partial melting on deformation mechanisms and LPO development in two common foliated felsic rocks, I performed general shear deformation experiments on a fine-grained quartzite and fine-grained gneiss at T = 800°C, 850°C, 900°C, 950°C, or 975°C, P = 1.5 GPa, and strain rate of 6*10-5/s. The quartzite (grain size ~30 microns) is composed of 90% quartz and 10% muscovite. The fine-grained gneiss (grain size ~50 microns) is composed of 43% quartz, 40% plagioclase, 16% biotite, and 1% accessory minerals. The foliation in the slices of each rock was oriented parallel to the shear plane between Al2O3 shear pistons with a cut made at 45° to the compression direction. Experiments were performed at a range of temperatures to change the melt fraction present in the rocks during deformation (Melt = ~0%, 0.25%, 0.5%, and 1%). The yield stress of Moine Thrust quartzite decreased as a function of increasing temperature from ~1000 to ~300 MPa. However, all the experiments with melt present (T equal to to greater than 850°C) significantly strain hardened after a shear strain (g) of 1. This hardening may be due to the presence of melt along grain boundaries which is absorbing water from the recrystallizing quartz grains which slows diffusive recovery in quartz. The Gne (open full item for complete abstract)

Committee: Caleb Holyoke (Advisor); John Peck (Committee Member); Molly Witter-Shelleman (Committee Member) Subjects: Earth; Environmental Geology; Experiments; Geochemistry; Geological; Geology; Geophysics; Geotechnology; High Temperature Physics; Mineralogy; Petrology

Master of Science, The Ohio State University, 2023, Aerospace Engineering

In this thesis there are two main studies. The first is an assessment of the role of mineral composition for Air Force Research Laboratory Test Dust (AFRL) for deposition in a realistic gas turbine engine environment. The second is an attempt to recreate Arizona Road Dust (ARD) synthetically by analyzing the chemical components of the natural dust and blending synthetic minerals together to match it. In the first study, experiments were performed on an effusion cooling test article with a coolant flow temperature of 894K and surface temperature of 1144K. Aerosolized dust with a 0-10 µm particle size distribution was delivered to the test article. The mineral recipe of AFRL was altered such that the presence of each of the five components ranged from 0% to 100%. For each of these AFRL recipe experiments several results were reported including capture efficiency, hole capture efficiency, mass flow reduction per gram, and normalized deposit height. Results are compared to a previous study of the inter-mineral synergies in an impingement cooling jet at the same temperature conditions. Despite differences in experimental facility flow geometry, overall agreement was found between the trends in deposition behavior of the dust blends. The strong deposition effects that were observed were shown to be related to adhesion forces of particles, mechanical properties, and chemical properties of the dust minerals. In the second study, X-Ray Diffraction (XRD) was performed on ARD to identify minerals present in a naturally sourced dust blend. Pure minerals were mixed in quantities that matched the XRD spectrum of ARD, and oxide content of this synthetic dust blend was shown to match the ISO standard (12103-1) to which ARD conforms. Particle size distribution was also matched to ARD (0-15 µm). Experiments were then conducted in four deposition facilities, one of which was representative of turbine hot section conditions (1500-1625K) and two were representative of internal coola (open full item for complete abstract)

Committee: Datta Gaitonde (Committee Member); Jeffrey Bons (Advisor) Subjects: Aerospace Engineering

Master of Science, The Ohio State University, 2022, Food Science and Technology

Processing of milk ingredients often requires thermal processes that induce inter- and intra- molecular reactions of proteins and lipids that can affect bioavailability and human health benefits. Milk fat globule membrane (MFGM), found in human and cow's milk, has numerous proteins and lipids linked to gut development, bactericidal effects, and neurodevelopment in infants. Another important constituent of cow's milk, β-lactoglobulin (β-LG), is a source of essential amino acids and enhances immune function. Though individually and in their native form these compounds have benefits to human health, it is unclear how thermal processing influences the interactions between β-LG and MFGM. This is important to understand when formulating and processing products and making nutritional claims. The objective of this work was to investigate the effect of heat treatment on the interactions within and between MFGM and β-LG via Quartz Crystal Microbalance with Dissipation (QCM-D). The interaction of interest is of the MFGM as it is used in industry, and not as purified single proteins or phospholipids used in model studies. Therefore, our focus is to maintain the complexity of the MFGM and consider its interaction to a purified β-LG. QCM-D is an extremely sensitive technique to measure changes in molecular interactions by modification of frequency and dissipation on surfaces creating adsorption patterns. In this study, interactions between and within native complex MFGM and β-LG were evaluated with QCM-D at interaction temperatures at and between 25—80 °C. Statistical analysis was performed to compare the effect of temperature on the difference in frequency (ΔF = ΔF45min — ΔF15min) and dissipation shifts (ΔD = ΔD45min — ΔD15min) and temperature effect on stabilization ratio (= (ΔD45min — ΔD15min ) / (ΔF45min — ΔF115min) in addition to comparison to other analytic parameters. Our hypotheses were: 1) Minimal frequency and dissipation shifts will occur at 25 and 40 °C, as (open full item for complete abstract)

Committee: Rafael Jiménez-Flores (Advisor); Sheila Jacobi (Committee Member); Osvaldo Campanella (Committee Member) Subjects: Food Science

Master of Science (MS), Bowling Green State University, 2022, Geology

Porosity and permeability are very important characteristics of reservoir rocks. Understanding the factors, specifically cementation, which control porosity and permeability are especially crucial when it comes to predictive modeling. Previous research has focused on the effects of grain size, temperature, and iron oxide on precipitation rates of cement between two surface substrates: fresh-fractured surfaces and naturally weathered surfaces. This study focused on image analysis techniques to assess their viability in calculating the percentage of porosity and cement in comparison to traditional point counting. Three sample charges were created using the dual fraction design after Williams (2012) and the experiments were carried out over the course of 168 hours (1 week) to 672 hours (4 weeks), under the experimental conditions of 450oC and 150 MPa confining pressure. The resulting samples were photographed and the resulting mosaics point counted and analyzed using the Fiji image software. Numerous image analysis techniques were attempted in which Lookup Tables and retinex-filtering were fairly successful in segmenting porosity and improving overall image quality for easier point counting. Point counting data showed measureable differences in precipitation rates where fresh-fractured surfaces had a faster rate while weathered surfaces had greater quantities of cement. Additionally, fresh-fractured surface experiments showed the presence of externally-sourced cement from the amorphous silica source and internally-sourced cement from grain dissolution. A possible explanation is the rapid precipitation cuts off transport pathways for the dissolved amorphous silica and there is a switchover to internal sources of cement via the dissolution of grains and grain fragments.

Committee: John R. Farver Ph.D (Committee Chair); Yuning Fu Ph.D (Committee Member); Kurt S. Panter Ph.D (Committee Member) Subjects: Earth; Environmental Geology; Environmental Science; Geology; Petroleum Geology

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

The Nathrop volcanics are the eroded remnants of domes that formed in the Early Oligocene (~30 Ma) on the edge of the Arkansas graben as part of the Late-Eocene‒Early Oligocene Central Colorado Volcanic Field (CCFV), and are representative of the highly evolved, alkaline, high-silica magmas found in this region associated with the onset of the Rio Grande Rift formation. Two of the edifices, Sugarloaf Mountain and Ruby Mountain, are examined in this study, with new 40Ar/39Ar dates and major and trace geochemistry allowing a comprehensive look at the formation and eruptive history of the domes. Stratigraphic units present at the domes are defined and described, with differences in lithofacies between the domes cataloged as well. The basal unit is a pyroclastic lithic-lapilli tuff (Tnt) overlain by a tuffaceous breccia (Tnb) formed from the autobrecciation of each domes' carapace. The Tnb has two subunits, a vitrophyre (Tnbv) and a perlite (Tnbp) that formed from welding and interactions with groundwater, respectively. The final, uppermost unit is flow-banded rhyolite lavas (Tnr). Three dates determined by the 40Ar/39Ar method using anorthoclase from deposits sourced from Ruby Mountain are indistinguishable within error from each other (30.402 ±0.026; 30.418 ±0.036; 30.454 ±0.040 Ma) but are younger than the two ages measured on sanidine from Sugarloaf Mountain (30.547 ±0.012 and 30.596 ±0.012 Ma). The age distinctions allow for an eruption sequence to be discerned. Geochemical analysis shows overlapping major and trace element chemistry between the domes with REE analyses suggesting fractional crystallization of feldspar to be the cause of most geochemical differences between the domes. Distinct differences in REE concentrations suggest the domes originate from separate magma bodies with a shared source, rather than from a single, chemically zoned magma chamber.

Committee: Kurt Panter Dr (Advisor); John Farver Dr (Committee Member); Jeff Snyder Dr (Committee Member) Subjects: Geochemistry; Geology; Geophysical

Doctor of Philosophy, University of Akron, 2017, Polymer Engineering

The methods to control hydrogels' toughness, ultimate stress, and fracture energy have received attention by researchers in recent years. The toughness and fracture energy can be increased by incorporating energy dissipating mechanisms. Physical crosslinks that can break and reform during stressing provide a simple method to modulate hydrogel mechanics. Hydrophobic physical crosslinks are a well suited for increasing toughness and fracture energy. This work investigated a physically crosslinked hydrogel composed of a random copolymer containing hydrophilic segments [N,N-dimethylacrylamide or N-isopropylacrylamide] and hydrophobic segments [2-(N-ethylperfluorooctane sulfonamido)ethyl acrylate (FOSA)] that form a network by the hydrophobic aggregation of FOSA segments into nanodomains. This system provides a model system for tough physically crosslinked hydrogels. How physical crosslinks impact swelling in laterally confined thin films, how the physical hydrogel and nanodomains deform in stress relaxation, and how absorbed water is altered due to confinement between hydrophobic nanodomain crosslinks were studied. Unlike the significantly reduced swelling of chemically crosslink thin film gels, the nature of the physical crosslinks' allows rearrangements in laterally confined thin films. These rearrangements allow the thin films to obtain an equilibrium swelling ratio similar to bulk. The osmotic pressure of the hydrophilic chain swelling induces these rearrangements. The result of this is the ability of physically crosslinked thin films ability to overcome thin film swelling constraints. An equilibrium water content/distribution can be obtained by rearrangement of the network. The route by which physical crosslink domains breakup and reform was identified by performing 1D elongation during small angle neutron scattering with contrast matching (CM-SANS). The stress induced relaxation time was found to span 5 orders of magnitude when fit with seven Maxwell element (open full item for complete abstract)

Committee: Bryan Vogt (Advisor); Robert Weiss (Advisor); Nicole Zacharia (Committee Chair); Matthew Becker (Committee Member); Bi-min Newby (Committee Member) Subjects: Materials Science; Polymers

Master of Science, University of Akron, 2017, Geology

A Griggs rig apparatus was used to perform a number of strain rate stepping and pressure stepping experiments of O+ oriented synthetic quartz crystals. These samples were annealed at 1 atm and 900°C for 24 hours to convert the gel type water inclusions to free water inclusions similar to those that are found in natural milky quartz. Strain rate stepping experiments were performed at temperatures from 1000°C to 750°C, and strain rates from 1.6 X 10-4 s-1 to 1.6 X 10-6s-1, while confining pressure was held constant at 1.5 GPa. These samples were observed to yield over a range of <10 to ~300 MPa in many cases, though under some of the conditions tested samples did not yield. Two pressure stepping experiments were performed, one at 800°C and one at 750°C, with a strain rate of 1.6 X 10-6s-1 and confining pressures between 0.6 GPa and 1.5 GPa. The sample strengths measured in the pressure stepping experiments were between ~30 MPa and ~60 MPa. Microstructures observed within deformed samples include undulatory extinction and deformation lamellae. The mechanical data from those experiments that were consistent with dislocation creep fit the flow law: ε′=0.00177*CH2O1.9*fH2O* ςdiff3.29* e(-268.6/(R*T)) Under natural conditions, this suggests plastic yielding of quartz occurs at ~9 km (~225°C) deep in the crust.

Committee: Caleb Holyoke III (Advisor); LaVerne Friberg (Committee Member); John Peck (Committee Member) Subjects: Geology; Geophysical; Geophysics

Doctor of Philosophy, The Ohio State University, 1966, Graduate School

Committee: Not Provided (Other) Subjects: Physics

Master of Science (MS), Ohio University, 2016, Geological Sciences (Arts and Sciences)

Zircon (zrn) and quartz (qtz) from twenty-four new plagiogranite and granitoid samples from the Oman ophiolite were analyzed for δ18O and trace elements to understand silicic magma petrogenesis in this setting. The data were organized into a relative stratigraphic position to compare δ18O with depth within the ophiolite crust. δ18Oqtz, generally more variable than coexisting δ sup>18Ozrn, have probably experienced sub-solidus exchange. Low-δ18Ozrn plagiogranite in the basal sheeted-dikes and dike-gabbro boundary increase towards mantle-like values in the deepest gabbro. Overall, these observations require some involvement of hydrothermally-altered crust in the production of felsic melts throughout the crust, either through hydrous partial melting of hydrated mafic crust, assimilation, or both. The return to mantle-like δ18Ozrn with depth towards the Moho likely reflects decreasing seawater-signatures of hydrating fluids and/or lower ater/rock ratios with depth rather than a difference in petrogenetic process. Peridotite hosted granitoid have δ18Ozrn=5.1-15.4‰ and δ 18Oqtz=7.0-18.5‰. Zircon from individual rocks yield uniform δ18O. Multiple mechanisms are therefore required to produce the high- and low-δ18O felsic magmas below the Moho. High-δ18O magmas can only be generated if mantle-like melt mixes with high-δ18O sediment in the mantle wedge, while low-δ18O magmas likely form similarly to crustal plagiogranite.

Committee: Craig Grimes PhD. (Advisor) Subjects: Geochemistry; Geology

Doctor of Philosophy (PhD), Ohio University, 2015, Chemical Engineering (Engineering and Technology)

In oil and gas production, internal corrosion of pipelines causes the highest incidence of recurring failures. Ensuring the integrity of ageing pipeline infrastructure is an increasingly important requirement. One of the most widely applied methods to reduce internal corrosion rates is the continuous injection of chemicals in very small quantities, called corrosion inhibitors. These chemical substances form thin films at the pipeline internal surface that reduce the magnitude of the cathodic and/or anodic reactions. However, the efficacy of such corrosion inhibitor films can be reduced by different factors such as multiphase flow, due to enhanced shear stress and mass transfer effects, loss of inhibitor due to adsorption on other interfaces such as solid particles, bubbles and droplets entrained by the bulk phase, and due to chemical interaction with other incompatible substances present in the stream. The first part of the present project investigated the electrochemical behavior of two organic corrosion inhibitors (a TOFA/DETA imidazolinium, and an alkylbenzyl dimethyl ammonium chloride), with and without an inorganic salt (sodium thiosulfate), and the resulting enhancement. The second part of the work explored the performance of corrosion inhibitor under multiphase (gas/liquid, solid/liquid) flow. The effect of gas/liquid multiphase flow was investigated using small and large scale apparatus. The small scale tests were conducted using a glass cell and a submersed jet impingement attachment with three different hydrodynamic patterns (water jet, CO2 bubbles impact, and water vapor cavitation). The large scale experiments were conducted applying different flow loops (hilly terrain and standing slug systems). Measurements of weight loss, linear polarization resistance (LPR), and adsorption mass (using an electrochemical quartz crystal microbalance, EQCM) were used to quantify the effect of wall shear stress on the performance and integrity of corrosion inhibit (open full item for complete abstract)

Committee: Nesic Srdjan Dr. (Advisor) Subjects: Chemical Engineering; Chemistry; Materials Science; Metallurgy

Master of Science, Miami University, 2015, Geology and Environmental Earth Science

Details regarding the mineralization patterns of gold in epithermal systems are poorly understood. The nature of interfaces of gold with dominant minerals such as quartz and adularia is not well constrained. A refined understanding of gold microtextures and the interface between gold and associated minerals could provide insight into the details of gold growth and mineralization and may contain indicators of gold ore concentration mechanisms. Furthermore, a refined understanding of the interface may explain variation in cyanide leaching extraction efficiency and may enable enhancement of recovery methods. Macrocrystalline samples from Round Mountain, Nevada were analyzed using field emissions scanning electron microscopy (FESEM) and focused ion beam (FIB) milling assisted transmission electron microscopy (TEM). Results suggest that the two dimensional growth mechanism is dominant and that colloidal gold and silver nanoparticles are present at the interface and may play an important role in the formation of these deposits.

Committee: Mark Krekeler (Advisor); John Rakovan (Committee Member); Hailiang Dong (Committee Member) Subjects: Geochemistry; Geological; Geology; Mineralogy; Mining

Master of Science (MS), Bowling Green State University, 2015, Geology

Regional fluid migrations associated with orogenic events have a number of significant geologic consequences in the continental interior, such as the emplacement of hydrocarbons, mineralization, and diagenesis. It is currently believed that fluids associated with the Alleghanian orogeny in the central Appalachians where sourced from the eastern portion of the Piedmont, migrated westward, passing below the Blue Ridge, into the Valley and Ridge region, and finally into the craton. Previous studies have provided details about fluids across much of the central Appalachians, but one gap remains: the western portion of the Piedmont. Using fluid inclusion microthermometry on vein samples throughout the western Piedmont, the trapping conditions and fluid composition were found and used to compare the fluid history of this region with that of other regions to determine if the Piedmont was part of the westward fluid migration. The fluids of the western Piedmont were found to be very uniform in terms of trapping conditions and fluid composition regardless of vein type, rock unit and lithology, and sample location. All inclusions were two-phase (L+V) and were found to consist of a low salinity H2O+NaCl brine with a large majority of them having homogenization temperatures between 140 and 200°C. The age of the veins and fluids cannot be well constrained. While most veins are probably associated with early phases of deformation and metamorphism during the late Ordovician Taconic orogeny and/or the early Silurian Cherokee orogeny, the fluid inclusions in them may be younger and related to recrystallization and/or reequilibration during younger events, such as the late Paleozoic Alleghanian orogeny. Considering the regionally uniform microthermometric properties of the inclusions, their relatively low trapping temperatures and pressures, low salinity fluid composition, the lack of reequilibration textures, and the lack of evidence for significant Alleghanian deformation in (open full item for complete abstract)

Committee: Charles Onasch (Advisor); John Farver (Committee Member); Kurt Panter (Committee Member) Subjects: Geology

Master of Science (MS), Bowling Green State University, 2015, Geology

Previous work demonstrated that microcrystalline quartz bands and cement in cataclasites related to faults in quartz-rich rocks may have derived from a silica gel parent fluid (Onasch et al., 2010). Occurrences of microcrystalline quartz on various fault surfaces of the Tuscarora Sandstone and other lithologies raised the possibility that a silica gel may have been present during faulting and significantly reduced the frictional strength. Fractured grains, trapped silica nanospheres, flow features, amorphous silica, uniform grain size distribution and recrystallized grains of low dislocation density within microcrystalline quartz on the fault surface are interpreted to have resulted from comminution and hydration of wallrock asperities along the fault surface coeval with Mode I fracturing and subsequent gel formation that resulted in dynamic weakening. The viscous gel may have promoted greater displacements that allowed migration of the gel from the fault surface into adjacent open Mode I fractures to rapidly precipitate opaline phases and upon silica depletion, quartz microveins less rapidly. Complex mutually crosscutting relations between microfractures, microcrystalline quartz and microveins as well as presence of brecciated clasts within breccia indicate multiple episodes of brittle deformation. Mutually overprinting textures between brittle and fault creep microstructures (stylolites) suggest alternating brittle and ductile episodes. As silica-rich rocks are common, understanding the mechanics associated with the formation of silica gel on fault surfaces of quartz-rich rocks may provide new insight into mechanics associated with other microcrystalline quartz-hosted faults in silica-rich rocks.

Committee: Charles Onasch (Advisor); John Farver (Committee Member); Jeff Snyder (Committee Member) Subjects: Geology

PhD, University of Cincinnati, 2009, Medicine : Industrial Hygiene (Environmental Health)

Changes in work practices and dust exposures following training were evaluated among workers engaged in small-scale demolition of concrete and masonry structures/buildings. One-page employee and multiple-page supervisor task-based good work practice control guidance sheets (TB-GWP-CGSs) were adapted from existing documents and workers were trained in use of the information. Interactive hands-on training was delivered to 26 workers from two demolition crews, and then evaluated using a chain of evidence with seven levels. A pre-and-post walkthrough survey was used by trained observers to document work practices, and NIOSH 0600 and NIOSH 7500 methods were used to assess silica dust exposure levels. Worker feedback indicated that the training was effective and useful. Workers acquired knowledge (84% increase, p<0.001) and mastered skills in the application of TB-GWP-CGSs. The difference of proportions between use of work practice components before and after the intervention was statistically significant (p<0.005). The alpha quartz percent ranged from 18 to 40% in six bulk samples collected from five different demolition sites. The percent reduction in dust exposure ranged from 40 to 78% after the intervention. The maximum silica exposure measured in a crew was reduced from 18 to 85% after the intervention. Small-sample size and results below the limit of detection prevented additional statistical inference. The intervention was successfully developed and implemented. Following training substantial changes in work practices were observed, including preplanning, use of wet methods, natural ventilation and end-of-task review. Consistency in inter-observer ratings and observations by the trained observers suggest good reliability and validity of the walkthrough survey of the instruments. Respirable dust and respirable quartz exposure levels indicated reduction following training. The approach used in this study demonstrated the short-term benefit of training in changing (open full item for complete abstract)

Committee: Carol Rice PhD, CIH (Committee Chair); Thomas Lentz PhD, MPH (Committee Member); James Lockey MD, MS (Committee Member); Richard Niemeier PhD (Committee Member); Paul Succop PhD (Committee Member) Subjects: Biomedical Research; Health Education; Public Health

Doctor of Philosophy, The Ohio State University, 2006, Materials Science and Engineering

This dissertation reports findings on three different but related topics. Determination of cathodic kinetics for Al-containing phases is essential to characterize the corrosion behavior of high strength Al alloys. However, the current density measured from a potentiostat can be different than the true cathodic current because anodic dissolution occurs during cathodic polarization of Al alloys and a potentiostat only senses the net current. Therefore, it is necessary to use a nonelectrochemical measurement, such as Eletrochemical Quartz Crystal Microbalance (EQCM) technique. EQCM was used on thin film compositional analogs of S phase (Al2CuMg) particle, which is an important intermetallic particle commonly found in Al alloys, to evaluate the true cathodic current density. In principle, it should be possible to apply the EQCM technique to determine kinetic parameters, e.g., diffusivity of water. However, little research has been performed to relate this information to delamination and subsequent corrosion of the substrate under the coatings. Therefore, it is interesting to use EQCM for investigating water uptake in organic coatings, delamination, and corrosion on coated Al electrode. Electrochemical Impedance Spectroscopy (EIS) cannot accurately sense the initial degradation of protective coatings as they are just starting to fail because the low frequency impedance is typically higher than the input impedance of the EIS system for reasonably-sized samples. Changes in corrosion resistance of these good coatings cannot be sensed until a significant degradation occurs. Therefore, it is interesting to investigate other evaluation techniques to assess the early stage of organic coating failure. Potentiostatic Pulse Testing (PPT), which involves the application of potential steps instead of sine waves, holds promise for the evaluation of these protective coatings.

Committee: Gerald Frankel (Advisor) Subjects: Engineering, Materials Science

Master of Science (MS), Ohio University, 1996, Electrical Engineering & Computer Science (Engineering and Technology)

Fast time-domain-based GPS acquisition

Committee: Michael Braasch (Advisor) Subjects: