Compared to normal cells, cancer cells tend to have higher concentrations of reactive oxygen species (ROS) such as hydrogen peroxide (H2O2) due to an accelerated cellular metabolism. The high ROS content leaves cancer cells increasingly susceptible to oxidative stress-induced cell death. This susceptibility can be manipulated in selective cancer therapy by further increasing production of ROS or inhibiting peroxide removal systems or a combination of the two. Pharmacological ascorbate (high-dose intravenous ascorbate) has been shown to sensitize pancreatic cancer to ionizing radiation (IR) by increasing production of ROS such as H2O2. Glutathione reductase (GR) and thioredoxin reductase (TrxR) are both important enzymes in peroxide removal systems. GR and TrxR function to recycle key electron donors in the cellular removal of H2O2. We hypothesized that inhibiting the peroxide removal systems via inhibition of GR and TrxR would enhance ascorbate-induced cytotoxicity in pancreatic cancer cells. Inhibition of TrxR activity enhanced ascorbate-induced cytotoxicity in MIA PaCa-2 pancreatic cancer cells. Additionally, knockdown of GR protein expression in combination with pharmacological ascorbate treatment increased MIA PaCa-2 pancreatic cancer cell sensitivity to IR. In MIA PaCa-2 and 403 F1 patient-derived pancreatic cancer cells, inhibition of both TrxR and GR activity combined with pharmacological ascorbate enhanced radiosensitivity. However, this effect was not seen in 339 patient-derived pancreatic cancer cells treated with the same dose of ascorbate. In conclusion, inhibition of TrxR activity, GR activity, or both enhances radiosensitivity and ascorbate-induced cytotoxicity in some, but not all, pancreatic cancer cell lines. Treatments combining ascorbate with inhibition of H2O2 removal may be an effective strategy for treatment of pancreatic adenocarcinoma.

No description available.

Algae are a diverse group of simple organisms that lack roots, stems or leaves and are able to use sunlight, carbon dioxide, and nutrients to produce complex compounds, such as carbohydrates, proteins and lipids. These compounds, especially lipids, are highly sought-after by agricultural, nutraceutical and energy interests. Although there is great potential for algae derived biofuels, there are technical and economic challenges associated with their cultivation. Relevant to this dissertation, the environmental impacts associated with algae cultivation can be reduced by using municipal and agricultural wastewaters as a water and nutrient source. This research was divided into three sections to address current challenges in the algal industry and science, technology, engineering and math (STEM) education. The sections were: 1) examination of the growth of indigenous algae on wastewater (centrate) produced from dewatering anaerobically digested municipal sludge, 2) examination of the effect of non-axenic conditions on the growth of three different algal cultures using wastewater from a recirculating aquaculture system (RAS), and 3) using wastewater treatment and algae to increase scientific inquiry in authentic science research with high school students. In the first section, indigenous algae were cultivated on centrate under natural light conditions in a semi-continuous photobioreactor. A non- linear bio-optical model was developed considering Michaelis-Menten photosynthesis-irradiance response. The bio-optical model was applied to fit the cumulative biomass data and had an R-squared value of 0.96. The second section examined the growth and accumulation of storage product. Higher calorific values were observed for all algae cultures when grown under non-axenic conditions, most likely due to significantly higher lipid contents. Significantly higher algal lipid contents under non-axenic conditions may be attributed to the stress of the presence of RAS microorganisms. Finally, having a university-based algal project with involvement of University of South Florida (USF) researchers, teachers and high school (HS) students facilitated increased scientific understanding and skills among HS students. Outcomes included graduate students gaining greater in-depth practical understanding as these students had to learn skills, such as designing a photobioreactor and then immediately had to teach HS students how to construct photobioreactors, design and conduct experiments, and gather scientific data. HS students gained a greater understanding of biological and chemical processes, such as photosynthesis. In addition, they learned important skills, such as calculating means and standard deviations using Excel, orally communicating scientific concepts and preparation of a PowerPoint presentation.

The purpose of this study was to examine social workers’ perspectives on the risk factors that are associated with cases of removal of infants. A quantitative survey design was utilized, using self-administered questionnaires that were distributed electronically to social workers located in San Bernardino County. The sample consisted of 94 participants, and the majority of the participants were White, non-Hispanic females. The study found that social workers identified substance abuse, the lack of infant’s physical safety in the home along with the age of the infant, and the lack of parents’ readiness to take part of the safety plan as highest risk factors for the removal of infants. Lastly, a surprising finding in this study was that a child’s ethnicity was indicated as a risk factor that increases the possibility of infant removal. It is recommended that social workers continue to receive trainings and other educational opportunities to enhance the social workers’ knowledge, values, and practice skills, to ensure the safety and well-being of all children.

Recently, there has been growing interest in using transition metals (TM) for catalytic and electromagnetic applications, due to the ability of TMs to form stable compounds in multiple oxidation states. In this research, the focus has been on the synthesis and characterization of carbon-supported TM nanoparticles (NPs), specifically palladium (Pd) and gold (Au) NPs, for catalytic applications, and transition metal oxides (TMO) NPs, specifically Fe3O4 NPs for electromagnetic applications. Carbon supports have several advantages, such as enabling even distribution of particles, offering large specific surface area with excellent electron conductivity, and relative chemical inertness. In this dissertation, for catalytic applications, emphasis was on removal of trichloroethylene (TCE) from groundwater. For this application, carbon-supported Pd/Au NP catalysts were developed. Pd was chosen because it is more active, stable and selective for desired end-products, and Au has shown to be a good promotor of Pd's catalytic activity. Often, commercially available Pd-based catalysts are made using harsh chemicals, which can be harmful to the environment. Here, an environmentally friendly process with aspects of green chemistry was developed to produce carbon-supported Pd/Au NP catalysts. This process uses a combination of sonochemistry and solvothermal syntheses. The carefully designed carbon-supported Pd/Au NP catalyst material was systematically characterized, tested against TCE, and optimized for increased rate of removal of TCE. Electron microscopy and spectroscopy techniques were used to study the material including structure, configuration and oxidative state. The Pd/Au NPs were found mainly to form clusters with an aggregate-PdShellAuCore structure. Using state-of-the-art direct detection with electron energy loss spectroscopy, the Pd NPs were found to have an oxidative state of zero (0). The formation of the catalyst material was studied in detail by varying several synthesis parameters including type of solvent, sonication time, synthesis temperature etc. The most optimized catalyst was found remove TCE at double the rate of corresponding commercial Pd-based catalysts in a hydrogen headspace. This material was found to catalyze the removal of TCE via traditional hydrodehalogenation and shows promise for the removal of other contaminants such as trichloropropane (TCP), carbon tetrachloride (CT). This green approach to make and optimize TM materials for specific applications was extended to TMOs, specifically magnetite (Fe3O4) and further developed for the application of electromagnetism. As catalysts, Fe3O4 is used for removal of p-nitrophenol from water. However, since the carbon-supported Pd/Au material system was developed and optimized for catalysis, here, carbon-supported Fe3O4 NPs were developed for electromagnetic applications. There has been growing interest in tuning the magnetic properties of materials at room temperature with the use of external electric fields, for long-term applications in data storage and spintronic devices. While a complete reversible change of material properties has not yet been achieved, some success in partial switching has been achieved using multiferroic spinel structures such as Fe3O4. These materials experience a change in magnetic moment at room temperature when exposed to the electric fields generated by electrochemical cells such as lithium ion batteries (LIBs) and supercapacitors (SC). In the past, a 1% reversible change was observed in Fe3O4 using LIBs. Here, building on the developments from previous material system, Fe3O4 NPs were directly hybridized onto the graphene support in order to increase the observable change in magnetic moment. The material was systematically designed and tested for this application, including a study of the material formation. A simple, environmentally friendly synthesis using the solvothermal process was implemented to make the graphene-supported Fe3O4 NPs. This new material was found to produce a reversible change of up to 18% in a LIB. In order to overcome some of the difficulties of testing with a LIB, a corresponding hybrid SC was designed, built and calibrated. The graphene-supported Fe3O4 NPs were found to produce a net 2% reversibility in the SC, which has not been reported before. The results from both the LIB and SC were analyzed to better understand the mechanism of switching in a spinel ferrite such as Fe3O4, which can help optimize the material for future applications. The focus of this dissertation was on the development of a methodology for carbon-supported TM and TMO NPs for specific applications. It is envisioned that this approach and strategy will contribute towards the future optimization of similar material systems for a multitude of applications.

Polluted stormwater, if not treated, can compromise water quality throughout our hydrologic cycle, adversely affecting aquatic ecosystems. Common stormwater pollutants, copper and zinc, have been identified as primary toxicants in multiple freshwater and marine environments. For small-scale generators, stormwater management can be cumbersome and implementation of common BMPs impractical thus catch basins are popular though not the most environmentally conscious and sustainable option. This study aims to characterize the potential of a mobile media filter operation for the treatment and on-site recycling of catch basin stormwater. The removal capacities of various commercially available filter media (e.g. a common perlite; Earthlite™, a medium largely composed of biochars; and Filter33™, a proprietary porous medium) were measured using binary injection solutions modeled after local catch basin stormwater characteristics. The results of filtration experiments, rapid small-scale column tests (RSSCTs), indicate that the transport of metals in Perlite is primarily impacted by nonspecific sorption whereas in Earthlite™ and Filter33™ both nonspecific and specific sorption are present. For all media and experimentation, there was a consistent preferential uptake of copper such that copper displayed delayed arrival and/or greater removal than zinc. Moreover, the observed snow plow effects and concentration plateaus in Earthlite™ and Filter33™ RSSCTs suggest rate limited ion exchange and specific sorption in addition to ion competition. Earthlite™ exhibited an approach velocity dependent removal efficiency in the RSSCTs and pseudo second order uptake behavior for zinc in kinetic batch experiments. At the lab scale equivalent of the proposed field scale flow rate, Filter33™ displayed the greatest average zinc removal of 8.6 mg/g. In all, this research indicates that test parameters (i.e. pH, competitive ions solutions, empty bed contact time, flow rate) based on the natural environment and field scale operation can greatly impact removal efficiency in filter media.

The maltreatment of children impacts individuals, communities, states, and societies. One response to the problem is the removal of children from their families, which can cause significant trauma for all involved. Moreover, the financial, legal, and emotional costs increase exponentially when subsequent re-removal, known as reactivation, occurs. Nationwide, the rate of reactivation averages just over 6%; in Arizona, the rate is significantly higher, with 11% of children being reactivated within 2 years of initial reunification. The purpose of this quantitative, non-experimental study was to determine whether poverty, ethnicity, parental substance use, parental employment, marital status, and number of children in the home is predictive of reactivation following reunification. The study was grounded in Bronfenbrenner's ecological theory and Brown's multiple risk factors model. Archival data of 627 family case files from a social service agency were analyzed using logistic regression. Results revealed that number of children was the only significant predictor, with fewer children resulting in higher reactivation rates. The lack of findings for the other predictor variables in light of extant research suggests that further research is needed to determine the unusually high rate of reactivations in this particular region. Further study may thus effect positive social change through findings that may impact educational and social welfare programs, legislative action, and enhancement of family skills training and resources.

Dans le cas des pièces aéronautiques de grandes dimensions et de formes complexes nécessitant un bon état de surface, les opérations de polissage sont la plupart du temps réalisées manuellement par des opérateurs spécialisés. Ces opérations étant longues, pénibles et coûteuses, il paraît pertinent de s’intéresser à leur automatisation. Dans ces travaux de thèse, nous nous intéressons à la mise en place d’un processus de polissage robotisé pour un train d'atterrissage en acier à haute résistance. La définition du processus robotisé passe par la définition des outils adéquats (taille de grain, forme et souplesse), des conditions de polissage (effort, vitesse de coupe, vitesse d’avance, angle de dépinçage et recouvrement) et le réglage des paramètres de la commande en effort en fonction du matériau à polir et de la spécification de rugosité visée. Un modèle d’enlèvement de matière est ensuite proposé afin de maîtriser le défaut d’état de surface généré pour des outils « disques ». Une campagne expérimentale permet enfin de valider la mise en œuvre du robot et du processus de polissage sur une pièce spécifique, notamment en ce qui concerne la chaîne numérique. / In the case of aircraft large parts and complex shapes requiring a good finish state, polishing operations are mostly performed manually by specialized operators. These operations are long, painful and expensive, it seems relevant to be interested in their automation. In the thesis work, we focus on the development of a robotic polishing process for high strength steel landing gear. The definition of the robotic process involves the definition of appropriate tools (grain size, shape and flexibility), polishing conditions (force, cutting speed, feed rate, inclination angle and overlap) and adjustment of parameters the force control based on the material to be polished and the specification roughness. A material removal model is then proposed to control the surface state generated for discs tools. Finally, an experimental campaign validates the implementation of the robot and the polishing process on a specific part, in particular as regards the numerical chain.

This thesis details the work completed in order to develop a hydrodynamic and nitrate transport and reaction model for Round Lake, a backwater on UMR Pool 8. This work begins with investigating the fundamentals of nitrogen removal in aquatic ecosystems and reviewing other combined hydrodynamic and nutrient modeling efforts. Field data were gathered to determine model boundary conditions and provide a basis for calibration and validation. Using this data, the flow regime in Round Lake was simulated. CFD applications to model particle residence times and species transport and reaction were used to analyze the effects local hydraulics have on nitrogen removal in the lake. Results demonstrated an ability for CFD to predict spatial variation of nitrate with this ecosystem.

Approximately 25% of households in the U.S. treat their wastewater onsite using conventional onsite wastewater treatment systems (OWTS). These systems typically include a septic tank or a series of septic tanks followed by a soil absorption system. They effectively remove biochemical oxygen demand (BOD), total suspended solids (TSS), fats and grease but are not designed to remove significant amounts of nitrogen. High nitrogen loading to coastal and ground waters can be dangerous to aquatic life and public health. Hence, there is a need for advanced onsite wastewater treatment systems that can effectively remove nitrogen. Making enhanced nitrogen removal for OWTS as our primary goal, a laboratory scale Hybrid Adsorption and Biological Treatment Systems (HABiTS) was developed and upon observation of its effective nitrogen removal capacity, a pilot demonstration study with two side-by-side HABiTS, one with recirculation and one without recirculation (only forward flow) were constructed and tested at the Northwest Regional Water Reclamation Facility in Hillsborough County (Florida). HABiTS employ biological nitrogen removal and ion exchange for effective nitrogen removal. HABiTS is a two-stage process which uses nitrification for the oxidation of ammonium to nitrate and ion exchange for ammonium adsorption that helps buffer transient loading and also acts as a biofilm carrier in its stage 1 biofilter and it uses tire-sulfur hybrid adsorption denitrification (T-SHAD) in its stage 2 biofilter. These sulfur pellets help promote sulfur oxidation denitrification (SOD) and tire chips are used for nitrate adsorption during transient loading conditions, as biofilm carriers for denitrifying bacteria, and can also be used as organic carbon source to promote heterotrophic denitrification because they leach organic carbon. For this research, HABiTS without recirculation is considered as the control system and the performance of HABiTS with recirculation was tested for its ability to further enhance nitrogen removal from HABiTS. Nitrified effluent recirculation is a common strategy employed in wastewater treatment for enhanced nitrogen removal. It is the reintroduction of semi-treated wastewater to pass through an anoxic pre-treatment chamber to achieve better quality effluent. Recirculation is said to improve and consistently remove nitrogen at any hydraulic loading rate and/or nitrogen concentration. This is because of the dilution of high BOD septic tank effluent with nitrified effluent which lowers COD:TKN ratio and also improves mass transfer of substrates in the stage 1 biofilter. Recirculation also provides some pre-denitrification in the pre-treatment chamber, thereby reducing nitrogen load on the system. The HABiTS with recirculation (R) was run at 1:1 ratio of nitrified effluent recirculation rate to the influent flow rate for 50 days, and at 3:1 ratio for the remaining period of this research (200 days). The forward flow system (FF) was run under constant conditions throughout the research and comparisons between the two systems were made for different water quality parameters (pH, DO, conductivity, alkalinity, TSS, chemical oxygen demand (COD), total nitrogen (TN), total phosphorus (TP) and various nitrogen species). The final effluent ammonium results showed that the system with recirculation removed consistently > 80% NH4+-N during 1:1 and 3:1 recirculation ratios whereas the forward flow system achieved 57% removal. Further, an average of 81% total inorganic nitrogen (TIN) removal from the system influent was seen in the recirculation system’s final effluent when compared to an average of 55% in forward flow system’s final effluent. This research explains in detail, the impact of nitrified effluent recirculation on enhanced nitrogen removal in onsite systems and the results presented in this thesis proved that nitrified effluent recirculation provides promising enhanced nitrogen removal in an onsite wastewater treatment system.