Climate change is predicted to have many diverse effects on freshwater lakes and reservoirs by increasing both hypolimnetic hypoxia and runoff, which will increase nutrient concentrations and degrade water quality. Hypoxic conditions can trigger the release of metals and nutrients from the sediments, i.e., internal loading, while storms can increase external nutrient loading to a waterbody. One potential solution for combating hypoxia is to use side stream supersaturation (SSS), a novel form of hypolimnetic oxygenation. First, in Chapter 1, I tested the efficacy of SSS operation to improve water quality in Falling Creek Reservoir (FCR), a shallow, eutrophic, drinking water reservoir. I found that SSS operation successfully increased hypolimnetic oxygen concentrations in FCR and suppressed internal loading of iron, manganese, and phosphorus. In Chapter 2, I manipulated inflow volumes to FCR and used SSS as a tool to alter hypolimnetic oxygen conditions in whole-ecosystem manipulations of internal and external nutrient loading. I observed that internal nitrogen and phosphorus loading during hypoxic conditions largely controlled the hypolimnetic mass of nutrients in FCR, regardless of inflow volumes, presumably as a result of the accumulated nutrients in its sediment from historical agriculture. Additionally, FCR consistently functioned as net sink of N and P throughout almost all of the treatments and substantially reduced nutrient export to downstream ecosystems. In summary, my research demonstrates the sensitivity of reservoir water quality to global change. / Master of Science

New synthetic advances in the control of nanoparticle size and shape along with the development of new surface modifications facilitates the growing use of nanomaterials in biomedical applications. Of particular interest are functional and biocompatible nanomaterials for sensing, imaging, and drug delivery. The goal of this research is to tailor the function of nanomaterials for biomedical applications by improving the biocompatibility of the systems. Our work demonstrates both a bottom up and a post synthetic approach for incorporating stability, stealth, and biocompatibility to metal based nanoparticle systems. Two main nanomaterial projects are the focus of this dissertation. We first investigated the development of a green synthetic procedure to produce gold nanoparticles for biological imaging and sensing. The size and morphology of gold nanoparticles directly impact their optical properties, which are important for their function as imaging agents or their use in sensor systems. In this project, a synthetic route based on the natural process of biomineralization was developed, where a designed protein scaffold initiates the nucleation and subsequent growth of gold ions. To gain insight into controlling the size and morphology of the synthesized nanoparticles, interactions between the gold ions and the protein surface were studied along with the effect of ionic strength on interactions and then subsequent crystal growth. We are able to control the size and morphology of the gold nanoparticles by altering the concentration or identity of protein scaffold, salt, or reducing agent. The second project involves the design and optimization of metal organic framework nanoparticles for an external stimulus triggered drug delivery system. This work demonstrates the advantages of using surface coatings for improved stability and functionalization. We show that the addition of a polyethylene glycol surface coating improved the colloidal stability and biocompatibility of the system. The nanoparticle was shown to successfully encapsulate a variety of small molecule cargo. This is the first report of photo-triggered degradation and subsequent release of the loaded cargo as a mechanism of stimuli-controlled drug delivery. Each of the aforementioned projects demonstrates the design, synthesis, and optimization of metal-based systems for use in biomedical applications. / Ph. D.

The purpose of this study was to compare the stiffness of a Type II external skeletal fixator (ESF) to a 3.5 mm locking compression plate (LCP) in axial compression, mediolateral, and craniocaudal bending in a fracture gap model. The hypothesis was that the Type II ESF would demonstrate comparable stiffness to the LCP. A bone simulant consisting of short fiber reinforced epoxy cylinders and a 40 mm fracture gap was used. The LCP construct consisted of a 12 hole 3.5 mm plate with three 3.5 mm bicortical locking screws per fragment. The Type II ESF construct consisted of 3 proximal full fixation pins (Centerface®) per fragment in the mediolateral plane, and 2 carbon fiber connecting rods. Five constructs of each were tested in non-destructive mediolateral and craniocaudal bending, and axial compression. Stiffness was determined from the slope of the elastic portion of force-displacement curves. A one-way ANOVA and a Tukey-Kramer multiple comparisons test were performed, with significance defined as p < 0.05. In mediolateral bending, the stiffness of the Type II ESF (mean ± standard deviation; 1584.2 N/mm ± 202.8 N/mm) was significantly greater than that of the LCP (110.0 N/mm ± 13.4 N/mm). In axial compression, the stiffness of the Type II ESF (679.1 N/mm ± 20.1 N/mm) was significantly greater than that of the LCP (221.2 N/mm ± 19.1 N/mm). There was no significant difference between the constructs in craniocaudal bending. This information can aid in decision-making for fracture fixation, although ideal stiffness for healing remains unknown. / Master of Science

Moving bed biofilm reactors (MBBRs) have been used effectively to reach low nutrient levels in northern Europe for nearly 20 years at cold temperatures. A relatively new technology to the US, the MBBR has most typically been used in a post-denitrification configuration with methanol for additional nitrate removal. Methanol has clearly been the most commonly used external carbon source for post-denitrification processes due to low cost and effectiveness. However, with the requirement for more US wastewater treatment plants to reach effluent total nitrogen levels approaching 3 mg/L, alternative electron donors could promote more rapid MBBR startup/acclimation times and increased cold weather denitrification rates. Bench-scale MBBRs evaluating four different electron donor sources, specifically methanol, ethanol, glycerol, and sulfide (added as Na2S), were operated continuously at 12 °C, and performance was monitored by weekly sampling and insitu batch substrate limiting profile testing. Ethanol and glycerol, though visually exhibited much higher biofilm carrier biomass content, performed better than methanol in terms of removal rate (0.9 and 1.0 versus 0.6 g N/m²/day.) Maximum denitrification rate measurements from profile testing suggested that ethanol and glycerol (2.2 and 1.9 g N/m²/day, respectively) exhibited rates that were four times that of methanol (0.49 g N/m²/day.) Sulfide also performed much better than any of the other three electron donors with maximum rates at 3.6 g N/m²/day and with yield (COD/NO₃-N) that was similar to or slightly less than that of methanol. Overall, the yield and carbon utilization rates were much lower than expected for all four electron donors and much lower than previously reported; indicating that there could be advantages for attached growth versus suspended growth processes in terms of carbon utilization rates. The batch limiting NO₃-N and COD profiles were also used to find effective K_s values. These kinetic parameters describe NO₃-N and COD limitations into the biofilm, which affect the overall denitrification rates. Compared to the other electron donors, the maximum rate for methanol was quite low, but the estimated K_s value was also low (0.4 mg/L N). This suggests high NO₃-N affinity and low mass transfer resistance. The other three electron donors estimated higher K_s values, indicating that these biofilms have high diffusion resistance. Biofilm process modeling is more complex than for mechanistic suspended growth, since mass transfer affects substrate to and into the biofilm. Simulating the bench-scale MBBR performance using BioWin 3.0, verified that μ_max and boundary layer thickness play key roles in determining rates of substrate utilization. Adjustments in these parameters made it possible to mimic the MBBRs, but it is difficult to determine whether the differences are due to the MBBR process or the model. / Master of Science

Nutrient runoff from excess land application of poultry litter in the Chesapeake Bay Watershed has caused damage to the Chesapeake Bay and lead to the need for alternative poultry litter disposal methods. This study provided an economic feasibility analysis of the use of poultry litter as a partial replacement of coal at an electrical generating unit in Virginia's Chesapeake Bay Watershed. Previous research on the feasibility of converting litter to energy failed to include uncertainty in benefit-cost variables, therefore, this study used risk analysis to incorporate variable uncertainty. Project net worth in previous studies was measured under a public investment scenario with risk neutral preferences but did not take into account risk averse preferences common in private investment. This paper compared benefits under both public risk neutral and private risk averse investor preferences. NPV results showed the proposed project to be feasible but sensitive to the acquisition cost of poultry litter, the unit ash value of litter, and future coal price projections. The maximum level of risk aversion required for feasibility increased when expected returns were measured on an investment scale compared to an annual income scale. Poultry litter combustion produced lower levels of NOx and SO₂ emissions compared to coal, therefore, emission allowance trading through the EPA market based trading programs generated additional benefits to the model and increased the maximum level of risk aversion permitted for feasibility. Results suggested the potential to dispose of 110 thousand tons of poultry litter per year from the Chesapeake Bay Watershed without violating EPA emission standards. / Master of Science

Yes / Seabed consolidation state is one of important factors for evaluating the foundation stability of the marine structures. Most previous studies focused on the seabed consolidation around breakwaters standing on the seabed surface. In this study, a numerical model, based on Biot’s poro-elasticity theory, is developed to investigate the unsaturated seabed consolidation around a nearshore pile foundation, in which the pile inserted depth leads to a different stress distribution. Seabed instabilities of shear failure by the pile self-weight and the potential liquefaction under the dynamic wave loading are also examined. Results indicate that (1) the presence of the inserted pile foundation increases the effective stresses below the foundation, while increases and decreases the effective stresses around the pile foundation for small (de/R<=3.3) and large (de/R>3.3) inserted depths, respectively, after seabed consolidation, (2) the aforementioned effects are relatively more significant for small inserted depth, large external loading, and small Young’s modulus, (3) the shear failure mainly occurs around the inserted pile foundation, rather than below the foundation as previously found for the located marine structures, and (4) wave-induced momentary liquefaction near the inserted pile foundation significantly increases with the increase of inserted depth, due to the change of seabed consolidation state. / National Natural Science Foundation for Distinguished Young Scholars (51425901), the National Natural Science Foundation of China (51209082, 51209083), the Natural Science Foundation of Jiangsu Province (BK20161509), the Fundamental Research Funds for the Central Universities (2015B15514), Jiangsu Graduate Research and Innovation Plan Grant (#CXLX11_0450) and the 111 project (B12032).

The problem called debt overhang has recently been observed in international financial relations between a sovereign country and foreign commercial banks. The term “debt overhang” expresses the situation where a sovereign country has borrowed money from foreign banks and has been unable to fulfill the scheduled repayments for some time. We formulate this problem as a noncooperative game with the lender banks as players where each decides either to sell its loan exposure to the debtor country at the present price of debt on the secondary market, or to wait and keep its exposure. We propose two approaches: a one-period approach (Chapter II), and a direct dynamic approach (Chapter III). In the one-period approach, we consider a representative period, while in the dynamic approach, the whole dynamics is directly considered. Both approaches are consistent and complementary in that the first approach considers the effect of a large number of banks, and the second approach captures the dynamic nature of the problem. In the one-period approach, we consider the behavior of many banks. In the model with n lender banks, there are many pure and mixed strategy Nash equilibria. However we show that in any equilibrium, the resulting secondary market price remains almost the same as the present price when the number of banks is large. In addition, we discuss the structure of the set of Nash equilibria. The second approach is a direct dynamic formalization of the same problem with two creditor banks. We show that in the dynamic game there exist three types of subgame perfect equilibria with the property called the time continuation. We consider the relationships between the equilibria of the dynamic game and those of the one-period approach and show that the one-period approach does not lose much of the dynamic nature of the problem. In every equilibrium, each bank waits in every period with high probability, and this probability is close to 1 when the interest rate is small. If the price function of debt is approximated by some homogeneous function for large values of debt, then the central equilibrium probability becomes almost stationary in the long run. The stationary probability is relatively high as long as the interest rate is low. Finally, in Chapter IV, we consider the duration of debt overhang with two lender banks. We show that the equilibrium duration of debt overhang converges to a constant when the length of a subperiod tends to zero. The constant is large when the degree of homogeneity of the price function is high. When the degree of the homogeneity is low, the constant is close to In 2/ In β², where β is the annual interest factor. These results as a whole are interpreted as a tendency for the problem of debt overhang to persist over a long time. / Ph. D.

Background: Awareness on climate change and sustainability have increased rapidly in the past decades. Companies are expected to implement sustainability into their operations and disclose information on their sustainability operations. These expectations can be seen as external push factors resulting from various sources, including institutional requirements, such as EU-directives, and societal stakeholders, such as local communities and customers. Large firms in Europe will be required to report on their sustainability measures and operations while experiencing pushes from all the parties affected by or affecting the companies’ operations. The effect of these push factors shapes the sustainability implementation in service firms and expose the company to internal resistances in adapting sustainability as a core part of the company. Purpose: The purpose of this thesis is to contribute to the understanding of sustainability implementation in service firms that results from a complex matrix of constantly evolving external forces. Method: This study is a qualitative study with a deductive reasoning. Data was collected by holding semi-structured interviews and conducting a thematic analysis based on the result. A conceptual framework was developed to present the linkages between the external push factors investigated. Conclusion: The study contributes to the understanding of the effects of the various external forces that shape the operations of companies. The findings highlight the impact of education and onboarding in awareness on internal sustainable development. The push from stakeholders can be seen through collaborations and engagements with all parties affected. As the operations of the companies are strongly shaped by current regulations, internal resistances arise from uncertainty and concerns of resources being misallocated leading to companies overlooking important areas of sustainable development.

Approved for public release; distribution in unlimited. / The purpose of a United States Army Directorate of Contracting (DOC) is to award or execute contracts for supplies or services and perform post-award contract administration functions for the Army installation and Army units stationed at the installation. The DOC accomplishes its purpose within the context of the Federal Acquisition System's Vision, which is to deliver on a timely basis the best value product or service to the customer, while maintaining the public's trust and fulfilling public policy objectives. A DOC must consider many external stakeholders to achieve its purpose. The basic premise of this thesis research is to improve a DOC's organizational effectiveness through the examination of its external environment, particularly, external stakeholders. The concept of stakeholder management concentrates on an organization's need to consider its relationships with specific stakeholder groups. An organization's ability to satisfy the desires of key stakeholders, meeting the stakeholders' criteria, is the key to an effective organization. Data were gathered from 15 government stakeholders and 14 contractors using a questionnaire that addressed such questions as: What are your organizations expectations and requirements of the DOC? How well did the DOC meet your needs and expectations? Does your organization control a resource needed by the DOC? The thesis summarizes findings and provides recommendations. The overall benefit of this thesis research is improved environmental awareness, which enables the DOC to become more effective in achieving its mission and meeting the desires of its external stakeholders. / Major, United States Army

The thesis analyses the trend in external economic balance of the Czech Republic since 2000. The main instruments for the analysis were found in level of balance of payments and external debt statistics. The emphasis is also placed on exchange rate of Czech currency which is considered to be one of the leading determinants of external economic relations. The main goal of this paper lies in examination of past, present and also expected future trend in external balance with respect to various indicators and to comparison with other EU members, especially with Central Europe region (Poland, Slovakia and Hungary). The thesis should provide general overview of external economic relations of the Czech Republic in situation when some European countries are being threatened by deep debt crisis and in some cases the life-line from European union or International Monetary Fund must come.