<p> A computer model is developed to simulate the emulsion copolymerization of styrene/butadiene in perfectly stirred batch, semi-batch or continuous flow reactors. The model considers free radical initiation by a redox mechanism, micellar particle nucleation, radical concentration as -a function of particle size, radical entry rate and termination rate and diffusion controlled termination and propagation reactions. It predicts conversion, copolymer composition, particle number, number and mass average molecular masses and tri- and tetra-functional branch frequencies. A simple method of estimating the particle size distribution is included in the model. Heat balances over the reactor and cooling jacket are considered and proportional-integra control of the reactor temperature is simulated.</p> <p> The model is used to simulate SBR copolymerization and styrene homopolymerization experimental data from the literature. These simulations tested only certain parts of the model and it is concluded that a more complete verification of the model can only be achieved by running a series of designed experiments. Qualitatively, the molecular mass, particle size distribution and reactor temperature predictions appear to be reasonable. The lack of appropriate temperature dependent rate constants currently limits the molecular mass predictions to isothermal conditions.</p> <p> A comparison of semi-batch operating policies designed to control copolymer composition is presented to illustrate the potential application of the model.</p> / Thesis / Master of Engineering (ME)

Occupational health surveys reported that first responders such as firefighters (FF) have some of the highest levels of cardiovascular disease in the nation from poor eating habits and lack of exercise. Three studies were established with goals to identify oxidative stress (OS) biomarkers and improve cardiovascular health for FF including: 1) a 28-day-carbohydrate restricted diet (CRD), 2) a heat-house search and clear protocol in personal protection equipment (PPE) plus curcumin supplementation, and 3) a treadmill exercise protocol in PPE with ketone salt supplementation. During those studies, stored blood plasma subsamples were evaluated for targeted antioxidants or untargeted metabolite concentration fluctuations using 1H NMR. Results from the 28-day-CRD tracked 40 metabolites consistently pre- and post-diet using 1H NMR platform. Of these metabolites’ acetone, β-hydroxybutyrate, leucine, and valine significantly upregulated while isoleucine downregulated. The plasma from the curcumin supplementation study contained 34 metabolites that were consistently identified. Lactate significantly upregulated immediate after exercise but returned to pre-exercise levels at 30 min post exercise while all the other metabolites were similar. From the ketone salt study 38 metabolites that were consistently identified from the pre- and post-exercise samples. Mean concentrations of acetone and β-hydroxybutyrate were significantly upregulated as were leucine and valine pre- and post-exercise while isoleucine downregulated. Lactate increased with ketone salt ingestion post-exercise and up to 30 min post-exercise but returned to normal at 24 h post-exercise compared to pre-exercise levels. Six other metabolites significantly differed in concentrations when compared across sampling times with no discernable impacts to OS or other notable trends. Multivariate analyses using principal components analysis (PCA), partial least squares-discriminant analysis (PLS-DA) and orthogonal partial least squares-discriminant analysis (OPLS-DA) models were not supported using cross-validation for Q2 coefficients and permutations values at p ≤ 0.05. From these results no metabolites were shown to support transient OS suppression.

The fermentation of syngas (a mixture of CO, CO2 and H2) to produce ethanol is of interest as an alternative fuel. Clostridium carboxidivorans, has been found to produce higher than average amounts of ethanol and butanol from CO-rich mixtures. This project sought to determine the effects of the redox level in the solution, partial pressures in the headspace and mass transfer limitations on the products obtained through fermentation of syngas. It was determined that cysteine sulfide has a greater effect on the redox level of the media used to grow bacteria, than does the gas composition. Therefore, changing gas composition during the process will have little effect on the redox. However, addition of cysteine sulfide may vary the redox level. When cells were first inoculated, the redox level dropped and leveled at -200 mV SHE for optimal growth. In addition, cells switch from acetic acid to ethanol production after a drop of 40-70 mV in the redox level. Different sizes of reactors were used, including 1 liter reactors (non-pressurized), 50 mL bottles (20 psig) and 100 mL bottles (20 psig). The 50 mL bottles have more than double the growth rate than the 100 mL bottles (0.57 day-1 compared to 0.20 day-1). Partial pressures were measured in these two sizes to determine the different consumptions and the effect of partial pressure on both growth and production of acetic acid/ethanol. It is clear that re-gassing the bottles every 12 hours to keep the pressure higher in the 100 mL bottles makes a significant difference in the growth, making them very similar to the 50 mL bottles. Both the 50 mL and 100 mL bottle were found to have essentially the same mass transfer rate (0.227 L/hr vs. 0.255 L/hr). However, because of headspace differences, there was more CO available for the 50 mL bottles (on a per liter basis) as compared to the 100 mL bottles. Mass transfer analysis proved useful in pointing out that all three reactors likely experienced mass transfer limitations such that mass transfer effects are critical to address when performing studies involving syngas fermentation.

Stora Enso is a well-established provider of renewable solution packaging and board materials.Board products for liquid packaging and folding cartons for food are particularly sensitive tothe microbiological contaminants. In the manufacturing process, microbiological growth occursdue to environmental favourable conditions. Most of the microorganisms eventually die in theboard machine. The microflora in the process consists mainly of bacteria from genera Bacillusand Paenibacillus, and these species have a unique characteristic of forming endospores. Thespores are non-vegetative capsules transformed from the dying bacteria, with its purpose ofprotecting the bacterial genome from the unfriendly environment as it passes through in theboard machine. The levels of spores found in the board products are usually low, but suddenpeaks of spores in the board products are unwanted for food and health safety. Bacterial andspore cultivation is a standard method to investigate microbiological activity. The method isinaccessible due to 48-hour incubation time for obtaining test results and does not provide anyoverview in a short time frame of where in the process that might triggered sporulation. In thelong run, it can cause production losses that affect the prospects of the board production.The purpose of this study is to investigate a new analysis method to facilitate identification andquantification of microbiological activity with ATP bioluminescence (AdenosineTriphosphate) measurement and redox potential, and as well investigate the main process sitethat possibly causes the issue. ATP bioluminescence measures the concentration of ATP inrelation to the number of bacterial cells. The study was limited to the broke system due to theclosed system and accumulation of microorganisms. The broke system manages the reuse ofdowngraded new paper board. For the laboratory work, 15 process positions were selected inthe broke system. Pulp were sampled from each process position for each laboratory workday,and measurements of ATP bioluminescence, redox potential, pH, temperature, TOC (totalorganic carbon), retention time, and bacterial and spore cultivation were completed as well. Thecollected data were studied in a multivariate analysis and correlograms were produced for eachprocess position. In addition, a parallel study of a lab scale broke tower simulation wasperformed to further investigate if the broke tower could be the source of the microbiologicalactivity.The obtained results showed low correlations between the process parameters and the totalbacterial and spore concentration. Similar results were obtained for ATP bioluminescence andredox potential, resulted in a low correlation to the total bacterial and spore concentration aswell. The simulation gave additional insight in the function of ATP bioluminescence and redoxpotential.The conclusion is that ATP bioluminescence is an accessible method due to high repeatability,however the reliability is lacking. The analysis is not reliable because of low correlationbetween the total bacterial and spore concentration. Redox potential is both a reliable andaccessible method to identify and quantify the microbiological growth in the system, becauseit signifies the environmental conditions for the bacterial growth. It has been proven in the brokesimulation. Further research is needed to understand the representation in relation to thebacterial growth behind each analysis in order to fully consider the analysing measurementapplicable. Due to low correlations between the variables in each process position, anyassumptions cannot be considered in any specific process position that might be main cause ofraised spore values in board products. / Stora Enso är en väletablerad leverantör av förnybara lösningar för förpackningar ochkartongmaterial. Kartongprodukter för vätskeförpackningar och vikkartong för livsmedel ärsärskilt känslig för mikrobiologisk aktivitet. I tillverkningsprocessen sker mikrobiologisktillväxt på grund av gynnsamma miljöförhållanden. De flesta av de vegetativa cellerna dör såsmåningom i kartongmaskinen, men en stor del av mikrofloran består av bakterier från släktenaBacillus och Paenibacillus. Dessa arter har en unik egenskap att bilda endosporer. Sporerna äricke-vegetativa kapslar som transformerats från de döende bakterierna, med syftet att skyddabakteriegenomet från den ogynnsamma miljön som passeras i genom maskinen. Nivåerna avsporer som finns i kartongprodukterna är låga, men plötsliga förhöjda värden av sporer ikartongprodukterna är oönskade för livsmedels- och hälsosäkerheten. Bakterie- och sporodlingär en standardmetod att undersöka den mikrobiologiska aktiviteten. Metoden är otillgängligvars resultat visas efter 48 timmar inkubation. Metoden ger ingen översikt var i processen somkan ha framkallats sporulering, och detta bildar en diffus överblick var i processen inom korttidsram som kan ha bidragit till sporuleringen. På lång sikt kan det orsakas produktionsförlustersom påverkar kartongproduktionens framtidsutsikter.Syftet med denna studie är att undersöka nya analysmetoder för att underlätta identifiering ochkvantifiering av mikrobiologisk aktivitet med en ATP bioluminescens (Adenosin Trifosfat)mätning och redoxpotential och även undersöka den huvudsakliga processposition som orsakardet huvudsakliga problemet. ATP bioluminescens mäter koncentrationen av ATP i förhållandetill antalet vegetativa celler. Studien begränsades till utskottssystemet på grund av slutet systemoch ansamling av mikroorganismer. För laborationsarbetet valdes 15 processpunkter ut iutskottssystemet. Utskottsmassan togs från varje processpunkt för varje laborationsdag, ochmätningar av ATP bioluminescens, redoxpotential, pH, temperatur, TOC (totalt organiskt kol),retentionstid och bakterie- och sporodling genomfördes också. De insamlade data studerades ien multivariat analys och korrelogram togs fram för varje processpunkt. En parallellundersökning genomfördes med en labbsaklig simulering av utskottstornet för att ytterligareundersöka om tornet är möjligtvis källan till den mikrobiologiska aktiviteten.De erhållna resultaten visade låg korrelation mellan processparametrarna och den totalabakterie- och sporkoncentrationerna i samtliga processpositioner. ATP bioluminescens ochredox potential erhöll låg korrelation mellan den totala bakterie- och sporkoncentrationen, mensimuleringen gav tydligare förståelse i de båda mätningarnas funktion.Slutsatsen är att ATP är en tillgänglig metod eftersom det är repeterbar. Däremot har det visatsatt den är opålitlig, på grund av den låga korrelationen mellan den totala bakteriella ochsporhalten. Redox potential är pålitlig att använda, vilket har visats i simuleringen. Denförklarar de miljömässiga förhållandena i systemet och på så sätt stärks förståelsen om denbakteriella tillväxten. Vidare forskning behövs för att förstå betydelsen i samband med denbakteriella tillväxten bakom varje mätning för att analysmetoden ska vara applicerbar. På grundav låga korrelationer mellan variablerna i varje processposition kan några antaganden intebeaktas i någon specifik processposition som kan vara huvudorsaken till förhöjda sporvärden ikartongprodukter.

Perturbation of cellular redox homeostasis to a more oxidized state has been linked to adverse human health effects such as diabetes and cancer. However, the impact of altering the regulation of redox homeostasis during development is not fully understood. Specifically, this project investigates the role of the Nrf2 antioxidant response pathway and its effect on glutathione (GSH; cellular redox buffer) at critical windows of development. To explore this, we used zebrafish embryos (Danio rerio) as a model due to the function of GSH and the Nrf2 being conserved among vertebrates. We exposed zebrafish embryos to three Nrf2 activators: two antioxidant enhancing molecules: sulforaphane (SFN; 40 µM) and Dimethyl fumarate (DFM; 7µM) as well as the pro-oxidant tert-Butylhydroquinone (tBHQ; 1µM) for 6 hours at critical windows development: 24, 48, 72 hours post fertilization (hpf). Following exposure, we visualized Nrf2 protein levels and glutathionylation rates using immunohistochemistry and confocal imaging. We found that changes in Nrf2 expression were dependent on the tissue type with there being significant changes in Nrf2 when looking at the pancreatic beta cells. Also in the beta cells, exposure to SFN, tBHQ, and DMF were found to increase Nrf2 translocation into the nucleus. Most notably, all three Nrf2 activators significantly altered glutathionylation levels depending on the time-point the zebrafish were exposed. SFN and tBHQ were also found to significantly increase glutathionylation at 48 and 72hpf, but led to a significant decrease at 96hpf while DMF increased glutathionylation at all three time-points. Interestingly, there was little correlation between Nrf2 protein levels and glutathionylation, but zebrafish with a mutated Nrf2 did have significantly different glutathionylation rates than the wild type fish. This suggests that oxidative stress is not the sole regulator of glutathionylation and instead Nrf2 may also be regulating glutathionylation through GSH storage. My data indicate that the effects of Nrf2 activation on Nrf2 levels and glutathionylation depend on the timing of exposure to the perturbing chemicals and the tissue type. Finding these windows of development where redox homeostasis is most sensitive in humans can allow for possible preventative and/or protective measures to oxidative stress during development.

<p>  </p> <p>Nowadays, clean and renewable energy sources like wind and solar power have been rapidly growing for the goal of phasing out traditional fossil fuels, achieving carbon neutrality, and realizing sustainable development. Long-duration and large-scale energy storage is needed to address the intermittent nature of these sources. Especially, redox flow battery (RFB) is an attractive energy storage device for large scale applications because of its high scalability, design flexibility, and intrinsic safety. The all vanadium redox flow battery stands for the state-of-the-art system, but the high vanadium cost and limited energy density are among the limiting factors for wide commercialization. Therefore, it is necessary to develop new RFB materials that are cost-effective and highly soluble. Organic redox-active molecules (redoxmers) hold great potential to satisfy these requirements due to structural diversity, tunable chemical and electrochemical properties, and earth-abundant sources. With rational structural design, organic redoxmers can show favorable properties such as high solubility, suitable redox potential, and good chemical stability. However, current efforts are mainly on the development of anolyte redoxmers, e.g. phenazine, anthraquinone and viologen. Only limited types of catholyte candidates have been reported such as ferrocene and TEMPO. The major reason for such slow-paced progress is the limited chemical stability of these catholyte redoxmers. To bridge this critical gap, my efforts are focused mainly on the design and development of promising catholyte redoxmers for both aqueous organic (AORFBs) and non-aqueous organic redox flow batteries (NRFBs).</p> <p>Phenoxazine functionalized with a hydrophilic tetraalkylammonium group demonstrates good water solubility and suitable redox potential. Cyclic voltammograms (CV) and flow cell testing were used to evaluate the electrochemical properties and battery performance, respectively. Besides, the battery fading mechanism was systematically investigated by CV, liquid chromatography mass spectra (LC-MS) and electron paramagnetic resonance (EPR) spectroscopy. The redoxmer decomposition mechanism analysis will benefit future redoxmer development by guiding the molecular design of more stable structure candidates. </p> <p>A structural design strategy for the development of novel TMPD-based (tetramethyl-<em>p</em>-phenylenediamine) catholyte redoxmers for NORFBs is presented. Two categories of functional groups, including oligo(ethylene glycol) (EG) either chains and phenyl rings, were incorporated into the TMPD core to improve solubility and stability in non-aqueous electrolytes, respectively. EPR characterization and bulk electrolyte (BE) analysis were carried out to evaluate the redoxmers stability. In addition, DFT studies were conducted to understand the impacts of functional groups on redox potential and chemical stability. The present work demonstrates the feasibility of constructing promising redoxmers from TMPD and provides insights into molecular designing of catholytes to achieve high solubility and excellent stability for non-aqueous redox flow batteries.</p>

The environmental mobility of Technetium-99 is inextricably tied to its oxidation state. Under oxidizing conditions Tc-99 predominates as the Tc(VII)O4- anion. This anion has a high solubility and is precluded from sorption on most soil or mineral surfaces, giving it a high environmental mobility. Under reducing conditions, Tc-99 predominates as Tc(IV)O2 or Tc(IV)2S7. Tc(IV) species tend to be insoluble and are therefore immobile. Due to this redox dichotomy, there has been significant interest in developing reductive immobilization strategies for Tc-99, particularly in anoxic environments where Tc(IV) is conventionally assumed to be stable. However, O2 is not the only common environmental oxidant. Many high valent manganese species are environmentally prolific and well known to exist in anoxic and overall reducing environments. These powerful oxidants can create localized oxidizing conditions in otherwise reducing environments. Limited research on the oxidation of Tc(IV) species has left a knowledge gap in the true recalcitrance of such immobilization forms in environmental settings. Our work aims to bridge this knowledge gap by studying the oxidation of Tc(IV) by various, environmentally common, high valent manganese species. Mn(III)-ligand complexes in particular have been overlooked. Up until recently, aqueous Mn(III) was assumed to be absent from the environment due to its disproportionation in aqueous systems without suitable complexing ligands. More recently, Mn(III)-ligand complexes have been shown to be prolific in a variety of natural waters. We have shown that various manganese oxides and Mn(III)-ligand complexes are capable of rapidly oxidizing Tc(IV) to Tc(VII), even in the absence of oxygen, resulting in dissolution of Tc-99 and release to the aqueous phase. This thesis presents novel information on the redox interface chemistry of Tc-99, which is crucial to developing effective remediation methods.

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