Doctor of Philosophy, Miami University, 2021, Ecology, Evolution and Environmental Biology

CHAPTER 1: Deeper waters are changing less consistently than surface waters in a global analysis of 102 lakes. As global climate change influences lake physical structure, this chapter analyzed long-term trends and drivers of five metrics of vertical thermal structure across 102 globally-distributed lakes. While increases in surface water temperatures and strength of stratification were common, trends in deepwater temperatures and thermocline depth were highly variable and poorly explained by geomorphological lake characteristics. CHAPTER 2: Attenuation of photosynthetically active radiation and ultraviolet radiation in response to changing dissolved organic carbon in browning lakes: Modeling and parametrization. Lake ecosystem models have limited capacity to address how changes in dissolved organic carbon (DOC) influence light attenuation and consequent vertical structural responses. We developed an update to the MyLake model to dynamically link light attenuation at multiple wavelengths, including the first parameterization of ultraviolet attenuation, with changing concentrations of DOC at the daily time step. CHAPTER 3: Earlier ice breakup induces changepoint responses in duration and variability of spring mixing and summer stratification duration in dimictic lakes. As ice cover duration has shortened in lakes worldwide, the subsequent periods of spring mixing and summer stratification are likely to change in response. We modeled the relationships between these two phenological periods vs. timing of ice breakup by "moving" a single lake across a latitudinal gradient. A key changepoint in the timing of ice breakup on May 9 determined the relative response of longer spring mixing vs. longer summer stratification duration. CHAPTER 4: High-frequency data reveal lake phenology is more strongly associated with oxygen depletion during winter than in summer. Using year-round high-frequency data from 14 lakes, we assessed the role of lake phenology on deepwate (open full item for complete abstract)

Committee: Craig Williamson (Advisor); Thomas Fisher (Committee Member); Tereza Jezkova (Committee Member); Stuart Jones (Committee Member); Michael Vanni (Committee Member); Jing Zhang (Committee Member) Subjects: Biology; Ecology; Limnology

Doctor of Philosophy, The Ohio State University, 2016, Physics

Protein surface hydration is essential to its structure, dynamics and function. Understanding the nature of hydration dynamics and water-protein interactions has fundamental significance in protein science. In this dissertation, we employed state-of-the-art femtosecond laser spectroscopy and site-directed mutagenesis to study protein surface hydration with femtosecond temporal resolution and single-residue spatial resolution. With intrinsic optical probe of tryptophan, we have elucidated the relationship between hydration water and local protein fluctuations and also mapped the global water motions around two globular proteins, rat liver fatty acid-binding protein (rLFABP) and the B1 immunoglobin-binding domain of Streptococcal protein G (GB1). First, we investigated the ultrafast internal conversion dynamics between the two concurrently excited states of tryptophan (1La and 1Lb) in GB1 and clarified the internal conversion (40-80 fs) will not smear the ultrafast solvation dynamics probed by tryptophan and the slowdown of hydration dynamics observed in proteins is true. Then we studied the solvation dynamics of the single tryptophan in Staphylococcal nuclease (SNase) by systematically mutating its three neighboring charged residues to determine the contributions from hydration water and protein charged side chains. The results unambiguously show that the total Stokes shifts of tryptophan are dominantly from hydration water relaxations. The protein motions are restricted on the picosecond time scales and always slower than hydration dynamics. To unravel the mechanism of water-protein interactions, we examined the temperature dependence of interfacial water and protein side-chain relaxations simultaneously for SNase. Significantly, the observations suggest that the relaxations of protein side chains are intrinsically correlated to hydration dynamics with the same energy barriers and that hydration water motions dominate water-protein coupling and drive protein surfac (open full item for complete abstract)

Committee: Dongping Zhong (Advisor); David Stroud (Committee Member); Ciriyam Jayaprakash (Committee Member); Comert Kural (Committee Member) Subjects: Biochemistry; Biophysics; Physics

Doctor of Philosophy, The Ohio State University, 2024, Chemistry

Understanding the fundamental interactions within and at the surface of atmospheric aerosol is of the utmost importance as they drive the properties of aerosol that influence global climate and public health. The first work presented herein explores the highly perturbed structure of water within systems inspired by phase separated organic aerosol. An approach is taken that combines polarized Raman spectroscopy and molecular dynamics to reveal the structural changes that occur as water is added incrementally to propylene carbonate (PC), a polar, aprotic solvent that is relevant in the environment and in electrochemical systems. Polarized Raman spectra of PC solutions were collected for water mole fractions 0.003 ≤ Χwater ≤ 0.296, which encompasses the solubility range of water in PC. The novel approach taken to the study of water-in-PC mixtures herein provides additional hydrogen bond and solvation characterization of this system that has not been achieveable in previous studies. Analysis of the polarized carbonyl Raman band in conjunction with simulations demonstrated that the bulk structure of the solvent remained unperturbed upon the addition of water. Experimental spectra in the O-H stretching region were decomposed through Gaussian fitting into sub-bands and studies on dilute HOD in H2O. With the aid of simulations, we identified these different bands as water arrangements having different degrees of hydrogen bonding. The observed water structure within PC indicates that water tends to self-aggregate, forming a hydrogen bond network that is distinctly different from the bulk and dependent on concentration. For example, at moderate concentrations, the most likely aggregate structures are chains of water molecules, each with two hydrogen bonds on average. The interaction of NO2 with organic interfaces is critical in atmospheric processing of marine and continental aerosol as well as in the development of NO2 sensing and trapping technologies. Recen (open full item for complete abstract)

Committee: Heather Allen (Advisor); Zachary Schultz (Committee Member); Bern Kohler (Committee Member) Subjects: Chemistry; Physical Chemistry

Doctor of Philosophy, University of Akron, 2018, Polymer Engineering

Hydrogels are water-swollen polymer networks that often exhibit biocompatibility and mechanical properties similar to many natural tissues. These properties grant hydrogels biomedical applications, such as tissue engineering, wound dressing and drug delivery. In recent years, supramolecular hydrogels with reversible, non-covalent crosslinks have received attention by researchers because of their toughness and the ability to be molded into complex shapes by conventional polymer processing techniques. During deformation, the reversible crosslinks (hydrophobic associations, ionic bonds, and/or hydrogen bondings) will dissociate and re-form to dissipate mechanical energy and prevent failure. In order to design tough supramolecular hydrogels, it is important to understand their structure-property relationships, i.e., the effect of crosslink structural change on the mechanical/rheological properties of hydrogels. This work investigated physically crosslinked hydrogels composed of random copolymers with hydrophilic segments [N,N-dimethylacrylamide (DMA) or 2-hydroxyethyl acrylate (HEA)] and hydrophobic segments [2-(N-ethylperfluorooctane sulfonamido)ethyl acrylate/methacrylate (FOSA or FOSM)]. When swollen in water, these copolymers form networks by the hydrophobic aggregation of FOSA/FOSM segments into nanodomains. The nanostructure of these hydrogels was elucidated by small angle neutron scattering (SANS) with contrast variation. The in-situ nanostructure evolution of the hydrogels during deformation and relaxation was monitored by small angle X-ray scattering (SAXS) and correlated with the mechanical properties of the hydrogels. During uniaxial extension, the rearrangement of crosslinks altered the network conformation and resulted in a non-affine deformation. With increasing strain rate, more rearrangement of crosslinks occurred to dissipate mechanical energy and toughen the hydrogel. At the same time, more structural anisotropy occurred due to less network relaxati (open full item for complete abstract)

Committee: Bryan Vogt (Advisor); Robert Weiss (Advisor); Abraham Joy (Committee Member); Mark Soucek (Committee Chair); Qixin Zhou (Committee Member) Subjects: Polymer Chemistry; Polymers

Doctor of Philosophy, The Ohio State University, 2016, Geography

The glaciers of the Cordillera Blanca Peru are rapidly retreating as a result of climate change, altering the timing, quantity and quality of water available to downstream users. Changes in water availability have serious implications for ecosystems, human livelihoods and regional economies. This dissertation investigates spatiotemporal changes in the glacier hydrologic system of the Cordillera Blanca Peru. It includes three major components. First, I develop multispectral unmanned aerial vehicles (UAV) and kite platforms capable of operating at over 5000m in mountain regions. Secondly, I deploy these platforms to investigate processes of glacier change and surface/subsurface hydrology within the glacial valleys of the Cordillera Blanca. Finally, I integrate UAV datasets with traditional field hydrology to improve our understanding of the spatiotemporal variability in soil moisture and its role in moderating groundwater storage within the Cordillera Blanca. I designed and deployed UAVs on multiple missions at over 5000masl in the Cordillera Blanca, Peru. After describing the UAV design in Chapter 2, this dissertation reports on results of four studies that utilise the UAV to address research questions within the region. Chapter 3 comprehensively assesses the accuracy of photogrammetrically derived structure from motion (SfM) digital elevation models (DEMs), by quantitatively and qualitatively comparing the data against surveyed GPS positions and LiDAR DEMs. Finding that accuracy is as good if not superior to low density LiDAR, with the high density SfM point clouds retaining unique surface details. Chapter 4 investigates the dynamics of glacier change over the debris covered Llaca glacier. I document the importance of debris cover and surface features such as ice cliffs in controlling melt rates. Average glacier downwasting is 0.75m over one year but is highly heterogeneous. Ice cliff horizontal recession rates of up to 25m annual were measured illustrating the i (open full item for complete abstract)

Committee: Bryan Mark PhD (Advisor); Darla Munroe PhD (Committee Member); Michael Durand PhD (Committee Member); Liu Desheng PhD (Committee Member) Subjects: Geography; Geomorphology; Hydrologic Sciences; Hydrology; Physical Geography; Remote Sensing; Robotics; Soil Sciences; Technology; Water Resource Management

MS, University of Cincinnati, 2014, Engineering and Applied Science: Mechanical Engineering

In present study, the enhancement of meniscus evaporation by changing meniscus shape and area was investigated. Rather than observing the meniscus shape directly, an alternative method has been utilized. A Condensation Particle Counter (CPC) structure, which benefits from meniscus evaporation of a porous media to make vapor for water droplet growth, has been introduced to analyze the production water droplet. By analyzing the size and concentration of the condensed water droplet from CPC, the enhancement of meniscus evaporation taken place at the porous media was determined. The meniscus shape and area alterations were controlled by applying an additional pressure onto the meniscus. The results of the bigger condensed water droplet and higher concentration clearly demonstrate that the enhancement has been achieved to the meniscus evaporation, which was led by changing of the additional pressure applied to the meniscus of the porous media.

Committee: Sang Young Son Ph.D. (Committee Chair); Pramod Kulkarni D.Sc. (Committee Member); Frank Gerner Ph.D. (Committee Member) Subjects: Mechanics

Doctor of Philosophy, The Ohio State University, 2010, Chemistry

The challenges to reveal the molecular organization and interactions at the biological and atmospheric relevant interfaces were confronted in this dissertation by using vibrational sum frequency generation (VSFG) spectroscopy. In particular, the interfaces of biological membrane represented by model phospholipid monolayers, and the aqueous organosulfur species (dimethyl suloxide, DMSO and methanesulfonic acid, MSA) are studied. A condensing effect is observed for the model phospholipid (dipalmitoylphosphatidylcholine, DPPC) monolayer on concentrated DMSO subphases. When the DMSO molecules interact with the phospholipid membranes, DMSO molecules squeeze aside the phospholipids, which cause them to form tightly packed domain structures as well as causing the membrane to expand. In addition, the miscibility of DMSO with water and its powerful solvation of many substances make the formed pores a transportation corridor across the membrane, which as a result accounts for the enhanced permeability of membranes upon exposure to DMSO. Similar effects were found through “in-situ” Brewster angle microscopy (BAM) on dipalmitoylphosphatidyl ethanolamine (DPPE), glycerol (DPPG), and serine (DPPS) phospholipids, indicating that the condensing effect is not dependant upon the phospholipid headgroup structure. Novel structural features of water confined in phospholipid monolayers are revealed. At the air/D2O/monolayer interface, the dangling OD stretching mode showed a marked frequency red-shift as well as spectral structure upon increasing the monolayer surface coverage. Furthermore, the dangling OD was found to exist even when a D2O surface was fully covered by the lipid molecules. This phenomenon was observed in monolayers formed with DPPC and with palmitic acid. The frequency red-shift of the dangling OD is interpreted to be due to the perturbation imposed by the lipid hydrophobic tail groups. In addition, phase sensitive vibrational sum frequency generation is employed to i (open full item for complete abstract)

Committee: Heather Allen (Advisor); Dennis Bong (Committee Member); Sherwin Singer (Committee Member); James Waldman (Committee Member) Subjects: Chemistry

Doctor of Philosophy, The Ohio State University, 2002, Soil Science

Research was conducted to determine how water table management affects select physical properties and carbon fractions of a Hoytville clay loam soil. The research took place at the Northwest Branch of the Ohio Agricultural Research and Development Center in Wood County, Ohio. Water table management treatments included subsurface drainage and subsurface drainage with subirrigation. Subirrigation was applied during the vegetative, flowering and seed fill stages of crop growth to maintain a constant water table at 0.25 m below the surface and prevent moisture stress in the crops. The cropping system was a corn soybean rotation with fall tillage with a chisel for both crops and spring leveling with a Roterra before planting soybeans. Results show a difference in water stable aggregates (WSA) at a depth of 0.4 – 0.75 meters with the subirrigated treatment having a lower percentage of WSA. The mean weight diameter of aggregates in the subirrigated treatment was smaller than in the subsurface drainage treatment at a depth of 0.3 – 0.75 meters. A shift in the pore size distribution toward smaller pores in the subirrigated treatment further supported “loss of stable soil structure” theory for the subirrigated treatment. Penetration resistance measurements also revealed a change in the structural stability of the soil at a depth of 0.30 – 0.45 meters. No differences were seen between water management treatments in the carbon fractions of the upper 0 – 0.20 meters of the soil. The CENTURY model was tested to determine if it could be used to predict levels of soil organic matter as a result of subirrigation. The model was unable to predict the amount of total SOM in the soil unless the starting value of carbon was lowered well below actual values. Subirrigation of the Hoytville soil led to a loss of stable structure at a depth of approximately 0.40 meters in the soil. The exact reason for the loss of soil structure is unclear but may be related to long periods of saturation res (open full item for complete abstract)

Committee: Norman Fausey (Advisor) Subjects:

Master of Science, University of Akron, 2013, Polymer Science

Tissue loss and end-stage organ failure has been a significant health challenge for millions of Americans, with the total national health cost exceeding $400 billion per year. Tissue engineering aims to address this challenge. During the process of tissue engineering, scaffolds and matrices are needed as supporting structures for cells to grow. Meanwhile, the roughness and stiffness of the scaffold material can largely influence cell growth and differentiation. The macro- and meso- structures of the scaffold, along with the functional groups or growth factors present on the surface plays an important role in cell function. Poly(ester urea) (PEU) is regarded as a promising biodegradable scaffold material for tissue engineering. In this study, physical and mechanical properties including Young's modulus, storage modulus, water uptake profile, and degradation rate for PEUs of different structures were tested. Two different amino acids, phenylalanine and leucine, and various diol lengths were used in the synthesis of these PEUs. In this study, the data show that changing the amino acid from leucine (LEU) to phenylalanine (PHE) can result in a 20 degree increase in Tg, and a 30% increase in storage modulus. Tuning the length of the diols reduces the stiffness of the polymer backbone affording multiple opportunities to tune the property of the polymer. A structure-property relationship profile for PEUs can therefore be established. The effect of macro structure of poly(L-lactic acid) (PLLA) and poly(e-caprolactone) (PCL) scaffold was also explored. Electrospinning was used to fabricate fibrous scaffold of non-woven mats. 4-dibenzocyclooctynol (DIBO) terminated PCL was electrospun into nanofibers. The existence of DIBO groups on the surface was characterized by attaching an azide functionalized florescent dye. DIBO-PLLA was electrospun into fiber mats and functionalized by YIGSR peptide via metal-free click reaction on the DIBO group. Both random and uniaxial aligne (open full item for complete abstract)

Committee: Matthew Becker Dr. (Advisor); Abraham Joy Dr. (Committee Member) Subjects: Materials Science; Nanoscience; Neurosciences; Polymer Chemistry; Polymers

Doctor of Philosophy (Ph.D.), University of Dayton, 2012, Biology

Hydraulic characteristics in lotic ecosystems are influential in the structure and function of aquatic benthic communities. Human activities and the increased demand for freshwater have caused the modification of natural flow regimes worldwide. Hydrological alterations, such as dams, diversions, and channelizations, are associated with ecological change and known to have detrimental effects on benthic communities. As a whole, this dissertation investigated the effects of hydraulic variables on the spatial distribution of macroinvertebrates and habitat template characteristics in tropical and temperate freshwater streams of the West Maui Mountains, Maui, Hawaii, and in Dayton, Ohio. The first two studies took place in Hawaiian mountain streams that have been diverted, often removing >95% of base flow, for development, agriculture and tourism, thus modifying the natural flow and altering habitat and species composition. A transplant study investigated the effects of water removal and increased density on dispersal and upstream migration of N. granosa. Initial mean upstream migration rate was 0.25, 0.66 and 1.16 m/d under reduced flow, natural flow and natural flow with increased snail density, respectively. Through calculations using rates from published studies of neritids migrating en masse or in long lines, we generated realistic time frames for N. granosa to migrate above diversions, ranging from 72 days to 2.5 years (aggregate) and 29 days to 1.1 years (long narrow line). By understanding upstream migration, recommendations for migratory pathway and population restoration can be applied globally for tropical amphidromous species. Secondly, habitat template, discharge, habitat flow, and macroinvertebrate insect indices were evaluated within riffle and cascade microhabitats upstream and downstream of the highest elevation diversion in four streams of the West Maui Mountains. A significant 44% reduction in macroinvertebrate density downstream of diversions was f (open full item for complete abstract)

Committee: Albert J. Burky PhD (Advisor); M. Eric Benbow PhD (Advisor); Karolyn Hansen PhD (Committee Member); Mollie McIntosh PhD (Committee Member); Mark Nielsen PhD (Committee Member); P. Kelly Williams PhD (Committee Member); Carl Friese PhD (Committee Member) Subjects: Biology