Bacterial contamination of food is a global concern. Methods of treating bacterial contamination are limited. Bacteriophages, bacterial viruses, offer a promising solution. However, bacteriophages may have limited application for foods that undergo sterilization processing, are inhospitable to organisms, or must be maintained in a dry state. This thesis focused on methods to expand the application of bacteriophages. First, bacteriophages were subjected to generalized stresses of desiccation, heat, and acidity, under laboratory conditions to propagate new populations with improved stress resistance. However, testing of these stress-resistant populations under real-world conditions failed to produce results comparable to generalized laboratory conditions. Success in the application of selected bacteriophages may require high situational specificity during selection, including in terms of food matrix and stress mechanics. The focus of our research shifted from the modification of bacteriophage populations themselves to the development of food-safe protective matrices. Designed matrices encapsulate bacteriophage for integration with modern food production and even the food products themselves. A pullulan-trehalose sugar powder was developed for the protection of a model bacteriophage from pasteurization. Microparticles were engineered such that the majority of the particle would be composed of trehalose as a stabilizer and polysaccharide pullulan was designed to accumulate at the particle surface to slow dissolution. This structure resulted in a bacteriophage powder that remained intact and protective over short-term high-temperature pasteurization, whereas unprotected bacteriophage experienced significant loss in titer. Leucine-lactose and leucine-lactose-maltodextrin microparticles were engineered for the inclusion of bacteriophage in powdered infant formula. The bacteriophage powder was designed as a dormant protection system that could activate upon reconstitution. The excipient system was formulated to not significantly affect the pH, composition, and dissolution of commercial infant formula. The bacteriophage powder was also engineered to match the shelf life and secondary shelf life of infant formula. Altogether, this thesis demonstrates that bacteriophage application in different foods can be expanded through particle engineering. / Thesis / Doctor of Philosophy (PhD) / Bacterial contamination of food can lead to widespread outbreaks and subsequent preventable deaths. Our best tool against bacteria, antibiotics, cannot be widely applied to food for risk to the natural human biome and creation of resistant bacteria. Bacteriophages, viruses that infect bacteria, are a naturally occurring bactericide that offer an alternative solution. This thesis focuses on improving the application of bacteriophages in food. First, bacteriophages are selected for resistance to common food processing stresses, such as heat, drying, and acidity, to prepare future generations that are stress-resistant. Second, a protective sugar powder was designed that could be used to add bacteriophages to milk before pasteurization. Post-pasteurization, the sugar would dissolve and release bacteriophage into the milk to deal with any post-processing contamination. Lastly, an infant-safe bacteriophage powder was developed that could be intermixed with powdered infant formula in an effort to reduce infant death due to the ingestion of bacteria.

The composition and stability of polymer-magnetite complexes is essential for their use as a treatment for retinal detachment, for drug targeting and delivery, and for use as a MRI contrast agent. This work outlines a general methodology to design well-defined, stable polymer-magnetite complexes. Colloidal modeling was developed and validated to describe polymer brush extension from the magnetite core. This allowed for the observation of deviations from expected behavior as well as the precise control of polymer-particle complex size. Application of the modified Derjaguin-Verwey-Landau-Overbeek (DLVO) theory allowed the determination of the polymer loading and molecular weight necessary to sterically stabilize primary magnetite particles. Anchoring of polyethers to the magnetite nanoparticle surface was examined using three different types of anchor groups: carboxylic acid, ammonium, and zwitterionic phosphonate. As assessed by dynamic light scattering (DLS), the zwitterionic phosphonate group provided far more robust anchoring than either the carboxylic acid or ammonium anchor groups, which was attributed to an extremely strong interaction between the phosphonate anchor and the magnetite surface. Coverage of the magnetite surface by the anchor group was found to be a critical design variable for the stability of the zwitterionic phosphonate groups, and the use of a tri-zwitterionic phosphonate anchor provided stability in phosphate buffered saline (PBS) for a large range of polymer loadings. Incorporation of an amphiphlic poly(propylene oxide)-b-poly(ethyelene oxide) (PPO-b-PEO) diblock copolymer attached to the magnetite surface was examined through colloidal modeling and DLS. The relaxivity of the complexes was related to aggregation behavior observed through DLS. This indicated the presence of a hydrophobic interaction between the PPO layers of neighboring complexes. When this interaction was large enough, the complexes exhibited an increased relaxivity and cellular uptake. Thus, we have developed a methodology that allows for design of polymer-magnetite complexes with controlled sizes (within 8% of predicted values). Application of this methodology incorporated with modified DLVO theory aids in the design of colloidally stable complexes with minimum polymer loading. Finally, determination of an anchor group stable in the presence of phosphate salts at all magnetite loadings allows for the design of materials with minimum polymer loadings in biological systems. / Ph. D.

The purpose of this study is to analyze the process of education in central Appalachia. Persistent economic and social problems in the region such as unemployment, low average incomes, low educational attainment, and widespread poverty have defied solution. This study uses primary data from high school-aged youths and their parents' in four rural school districts in Appalachia to examine incentive structures which encourage, or discourage, individuals from obtaining education. The study evaluates a number of influences on the value that individuals place on education including community and employer influences, the willingness of youths to relocate to obtain employment, and the perception of employment opportunities in the local community. The study also examines inter-generational aspects of educational behavior by analyzing the influence of socioeconomic background, and parental attitudes and values, on the attitudes and values of their children. The findings indicate that socioeconomic background, and parental and community influences have a significant impact on educational behavior in Appalachia. / Ph. D.

An innovative sampling technique employing extractant impregnated membranes is presented for the selective sorption and stabilization of specific oxidation states of chromium. Polymer-based selective ion traps employing the extractants tricaprylmethylammonium chloride (Aliquat-336) and di-(2-ethylhexyl) phosphoric acid (DEHPA) were used for the selective removal and enrichment of the anionic forms of Cr(VI) and cationic forms of Cr(III), respectively. Results show Aliquat-336 and DEHPA effectively remove Cr(VI) and Cr(III) from aqueous solutions. Extraction efficiency is independent of source concentration from 1-50 ppm but is dependent upon time, pH of the source, ionic strength, extractant concentration, composition of source phase, and choice of stripping agent and stripping agent concentration. Optimum conditions for Cr(VI) and Cr(III) were determined to be 1 v/v% Aliquat-336 and 30 v/v% DEHPA; an extraction time of at least 3-5 days; source phase pH between 3-5; and 1 M NaOH/ 0.5 M HNO3 as stripping agent for Cr(VI) and Cr(III) species, respectively. Batch extraction efficiencies of 97 +/- 3 % were obtained for the optimal conditions. Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES) was used for total chromium determination. UV-VIS spectrometry was used for Cr(VI) determination. Scanning Electron Microscopy revealed the physical structure of the polymeric supports and subsequent impregnation was evidenced by the SEM images. X-ray photoelectron spectroscopic results provided the elemental composition of the Versapor-450 membrane to be 71. 5% C, 7.0% O, 9.5% Cl and 12.0% N. The Whatman PP membrane was and 100.0 % C. Elemental composition of 1 v/v% Aliquat-336 on Versapor-450 and Whatman PP membrane was 92.3% C, 0.8% O, 3.6% N, and 3.3% Cl and 94.3% C, 3.3% N, and 2.4% Cl, respectively. Elemental composition of 30 v/v% DEHPA on Versapor-450 and Whatman PP membranes were 78.8% C, 3.4% P, 17.8% O and 76.3% C, 19.3% O, 4.4% P, respectively. Column studies under simulated groundwater conditions utilizing the extractant impregnated membranes showed no statistical difference in Cr(VI) recoveries from those obtained in batch experiments. Cr(III) extraction revealed a statistical difference in analyte recovery vs. batch experiments. This is attributed to the lowered pH and cationic interferences present in simulated groundwater. / Ph. D.

Video stabilization is an important aspect of video processing, especially for handheld devices where unintended camera movement can significantly degrade the resulting recording. This paper investigates four image based methods for video stabilization. The study explores the Lukas-Kanade, Inverse Compositional Lukas-Kanade, Farnebäck Optical Flow, and GMFlow methods, evaluating their sub-pixel accuracy, real-time performance, and robustness to in-frame motion such as a person walking in front of the camera. The results indicate that while all methods achieve sub-pixel precision, real-time execution on a mobile phone is not feasible with the current implementations. Furthermore, the methods exhibit varying levels of difficulty in handling in-frame motion, with RANSAC-based approaches partially compensating for non-camera-induced movement. The paper also discusses the potential of machine learning techniques, represented by GMFlow, in enhancing stabilization quality at the cost of computational complexity. The findings offer valuable insights for the development of more efficient and robust video stabilization solutions.

Undrained triaxial tests were conducted to develop the constitutive relationships for two agricultural soils, which could be used for the finite element analysis of multipass effects of vehicles on soil compaction. Sandy-clay and sandy-silt samples were loaded and unloaded three times to levels of 138 kPa to simulate three passes of an agricultural tractor. An axial loading rate of 200 mm/min was used to include the dynamic effects of rapid loading from the vehicles. An Instron Universal Testing Machine was used to provide this loading rate. During the tests, a microcomputer based data acquisition system recorded axial force and strain. The system recorded 28 values per second. Tests were conducted at four confining pressures; 17.2, 24.1, 34.4 and 41.4 kPa. Plots for deviatoric stress and axial strain were found to be bilinear. Initial and latter portions of the curve were assumed to represent the elastic and plastic deformations of the sample, respectively. Assuming an associated flow rule, an elastic-plastic constitutive model was developed based on a Mohr-Coulomb failure surface. The constitutive model developed was evaluated by simulating a triaxial test at a confining pressure of 28 kPa. Initial conditions were computed by substituting the boundary stresses into the model to determine the elastic-plastic matrix. Incremental loads were applied up to the maximum stress level. For each increment of load, the elastic-plastic matrix was updated from the previous load application. The simulated data compared fairly well with experimental results, but tended to overpredict at higher stress levels. Based on a comparison with existing elastic-plastic models, the derived model appears to be well suited for substitution into the finite element method for studying soil compaction resulting from multipass effects of tractors. / M.S.

M.S.

Soil organic matter (SOM) is a critical biogeochemical pool that can be managed as part of global efforts to conserve nutrients and enhance carbon (C) sequestration. But reliably increasing SOM has proven difficult because most of the organic matter that enters soil as plant litter and organic amendments (i.e., compost, manure) is susceptible to decomposition by soil microorganisms and eventually is lost to the environment as greenhouse gases and non-point source pollution. Many soils lack the physical and/or chemical properties that enable some human-modified soils (e.g., terra preta soils in the Amazon Basin) to stabilize and retain C and nutrients in SOM while maintaining relatively high levels of productivity compared to surrounding natural soils that formed under similar conditions. I hypothesized that two of the major stabilizers of organic matter common to terra preta soils of the Amazon basin – black carbon (biochar) and poorly crystalline, reactive iron (Fe) minerals – could be applied to a fine-textured soil from Southwest Virginia to improve the accumulation and retention of C and nitrogen (N). I used a field experiment to compare the effects of three types of locally-produced biochars applied with and without an organic N fertilizer (blood meal) on soil C and N availability. I then used an incubation experiment featuring the soils from the aforementioned field experiment to examine the effects of applying Fe2+ -treated manure effluent on the retention of C and N in unamended and hardwood biochar-amended soils. I found that biochar adsorbed inorganic N in all cases, while providing a reliable, stable increase in SOM due to its recalcitrant nature. However, the manure effluent used in the incubation experiment stimulated the decomposition of mineral-associated organic matter (MAOM), with the addition of Fe2+ to the manure mitigating this apparent positive priming effect and the presence of biochar actually reversing this effect and promoting an increase in MAOM following manure application to biochar-amended soil. Overall, biochar stimulated the retention of N by decreasing the leachable inorganic N in the soil and enhanced soil C stocks. Additionally, biochar applications had the added benefit of promoting the accumulation of manure in soil as stable, microbially-processed MAOM, while co-applying Fe2+ with manure only served to inhibit the priming of native soil C. / Master of Science / Organic matter is an important constituent of all soils. Farmers and gardeners would like to increase the organic matter on their lands to improve their crop yields and health of their soils, yet people in many regions of the world struggle with actually getting long-lasting forms of organic matter to accumulate in soils. Moreover, managing soils to increase the amount of carbon stored in these long-lasting forms has the benefit of offsetting human contributions to atmospheric carbon dioxide and global warming. Some soils stabilize and build up organic matter more efficiently than others, and I hypothesized that if two well-known soil materials that help to stabilize organic matter – charcoal and iron – were added to a soil, then the accumulation of organic matter in the soil could be improved. The first part of my research was a field experiment in which three different kinds of charcoal were added either with or without an organic fertilizer to the soil in a Southwest Virginia pasture. I then measured the amount of carbon in the soil and determined that charcoal additions increased soil carbon and helped to retain mobile forms of plant nutrients. The second part of my research used the charcoal-treated and untreated soils from the field experiment for a project where cow manure was co-applied with three levels of iron and added to soils in jars in a controlled laboratory setting. The jars were then maintained at an ideal moisture and temperature for the growth of microbes for 70 days and analyzed afterwards. I found that the manure caused the organic matter in the soil to be consumed by microbes, while charcoal caused the organic matter from the manure to accumulate and remain. Adding iron with the manure prevented the microbes from consuming the pre-existing organic matter in the soil, but did not contribute to the retention of the manure in the soil. Overall, while both iron and charcoal influenced the retention of organic matter in soil, biochar proved to be more effective at stabilizing manure organic matter than the iron additions.

This thesis examines the wartime wage stabilization program in detail, and how it may help with controlling inflation in general.

Yes / The use of peptides to nucleate, grow, and stabilize nanoparticles in aqueous media via non-covalent interactions offers new possibilities for creating functional, water-dispersed inorganic/organic hybrid materials, particularly for Au nanoparticles. Numerous previous studies have identified peptide sequences that both possess a strong binding affinity for Au surfaces and are capable of supporting nanoparticle growth in water. However, recent studies have shown that not all such peptide sequences can produce stable dispersions of these nanoparticles. Here, via integrated experiments and molecular modeling, we provide new insights into the many factors that influence Au nanoparticle growth and stabilization in aqueous media. We define colloidal stability by the absence of visible precipitation after at least 24 hours post-synthesis. We use binding affinity measurements, nanoparticle synthesis, characterization and stabilization assays, and molecular modeling, to investigate a set of sequences based on two known peptides with strong affinity for Au. This set of biomolecules is designed to probe specific sequence and context effects using both point mutations and global reorganization of the peptides. Our data confirm, for a broader range of sequences, that Au nanoparticle/peptide binding affinity alone is not predictive of peptide-mediated colloidal stability. By comparing nanoparticle stabilization assay outcomes with molecular simulations, we establish a correlation between the colloidal stability of the Au nanoparticles and the degree of conformational diversity in the surface-adsorbed peptides. Our findings suggest future routes to engineer peptide sequences for bio-based growth and dispersion of functional nanoparticles in aqueous media. / Air Office of Scientific Research, grant number FA9550-12-1-0226.