Dissertations / Theses on the topic 'SCR reaction'

The reaction mechanism for the Selective Catalytic Reduction (SCR) of NO by NH3 on V2O5 surface was simulated by means of density functional theory (DFT) calculations performed at B3LYP/6-31G** level. As the initiation reaction, ammonia activation on V2O5 was investigated. Coordinate driving calculations showed that ammonia is adsorbed on Brø
nsted acidic V-OH site as NH4 + species by a nonactivated process with a relative energy of -23.6kcal/mol. Vibration frequencies were calculated as 1421, 1650, 2857 and 2900cm-1 for the optimized geometry, in agreement with the experimental literature. Transition state with a relative energy of -17.1kcal/mol was also obtained. At the end of the Lewis acidic ammonia interaction calculations, it was observed that ammonia is hardly adsorbed on the surface. Therefore, it is concluded that the SCR reaction is initiated more favorably by the Brø
nsted acidic ammonia adsorption. As the second step of the SCR reaction, NO interaction with the preadsorbed NH4 + species was investigated. Accordingly, NO interaction results in the formation of gas phase NH2NO molecule with a relative energy difference of 6.4kcal/mol. For the rest of the reaction sequence, gas phase decomposition of NH2NO was considered. Firstly, one of the hydrogen atoms of NH2NO migrates to oxygen. It then isomerizes in the second step. After that, the reaction proceeds with the isomerization of the other hydrogen. Finally, a second hydrogen atom migration to the oxygen leads to the formation of N2 and H2O. Total relative energy for this reaction series was obtained as -60.12kcal/mol, in agreement with the literature.

The reaction mechanism for the selective catalytic reduction (SCR) of nitric oxide by ammonia on (010) V2O5 surface represented by a V2O9H8 cluster was simulated by density functional theory (DFT) calculations. The computations indicated that SCR reaction consisted of three main parts. In the first part ammonia activation on Brø
nsted acidic V-OH site as NH4+ species by a nonactivated process takes place. The second part includes the interaction of NO with pre-adsorbed NH4 + species to eventually form nitrosamide (NH2NO). The rate limiting step for this part as well as for the total SCR reaction is identified as NH3NHO formation reaction. The last part consists of the decomposition of NH2NO on the cluster which takes advantage of a hydrogen transfer mechanism between the active V=O and V-OH groups. Water and ammonia adsorption and dissociation are investigated on (101) and (001) anatase surfaces both represented by totally fixed and partially relaxed Ti2O9H10 clusters. Adsorption of H2O and NH3 by H-bonding on previously H2O and NH3 dissociated systems are also considered. By use of a (001) relaxed Ti2O9H10 cluster, the role of anatase support on SCR reaction is investigated. Since NH2NO formation on Ti2O9H10 cluster requires lower activation barriers than on V2O5 surface, it is proposed that the role of titanium dioxide on SCR reaction could be forming NH2NO. The role of vanadium oxide is crucial in terms of dissociating this product into H2O and N2. Finally, NH3 adsorption is studied on a V2TiO14H14 cluster which represents a model for vanadia/titania surface.

THE EFFECTS OF CERIA ADDITION ON AGING AND SULFATION OF LEAN NOx TRAPS FOR STAND ALONE AND LNT-SCR APPLICATIONS Model powder and fully formulated monolithic lean NOx trap (LNT) catalysts were used to investigate the effect of ceria on desulfation behavior. Temperature-programmed reduction (TPR) experiments (model catalysts) showed each of the oxide phases present is able to store sulfur and possesses distinct behavior (temperature at which desulfation occurs). La-CeO2 or CeO2-ZrO2-containing samples (monoliths) showed a greater resistance to deactivation during sulfation and required lower temperatures to restore the NOx storage efficiency to its pre-sulfation value. Fully formulated monolithic LNT catalysts containing varying amounts of Pt, Rh and BaO were subjected to accelerated aging to elucidate the effect of washcoat composition on LNT aging. Elemental analysis revealed that residual sulfur, associated with the Ba phase, decreased catalyst NOx storage capacity and that sintering of the precious metals resulted in decreased contact between the Pt and Ba phases. Spatially-resolved inlet capillary mass spectrometry (SpaciMS) was employed to understand the factors influencing the selectivity of NOx reduction in LNT catalysts degreened and thermally aged) containing Pt, Rh, BaO and Al2O3, and contained La-stabilized CeO2. Stretching of the NOx storage and reduction zone (NSR) zone resulted in increased selectivity to NH3 due to the fact that less catalyst was available to consume NH3 by either the NH3-NOx SCR reaction or the NH3-O2 reaction. Additionally, the loss of oxygen storage capacity (OSC) and NOx storage sites, along with the decreased rate of NOx diffusion to Pt/Rh sites, led to an increase in the rate of propagation of the reductant front after aging, in turn, resulting in increased H2:NOx ratios at the Pt/Rh sites and consequently increased selectivity to NH3. Finally, a crystallite scale model was used to predict selectivity to NH3 from the LNT catalysts during rich conditions after a fixed amount of NOx was stored during lean conditions. Both the experimental and model predicted data showed that the production of NH3 is limited by the rate of diffusion from the Ba storage sites to the Pt particles at 200 °C. At 300 °C, the process is limited by the rate at which H2 is fed to the reactor.

An integrated NOx adsorption-reduction process has been proposed in this study for the treatment of flue gases under lean-burn conditions by decoupling the adsorption and reduction into two different zones. The hypothesis has then been validated in a novel internal circulating fluidized bed. The adsorption and reaction performance of Fe/ZSM-5 for the selective catalytic reduction (SCR) of NOx with propylene was investigated in a fixed bed reactor. The fine Fe/ZSM-5(Albemarle) catalyst showed reasonable NOx adsorption capacity, and the adsorption performance of the catalyst was closely related to the particle size and other catalyst properties. Fe/ZSM-5 catalyst was sensitive to the reaction temperature and space velocity, and exhibited acceptable activity when O₂ concentration was controlled at a low level. Water in the flue gas was found to slightly enhance the reactivity of Fe/ZSM-5(Albemarle), while the presence of CO₂ showed little effect. SO₂ severely inhibited the reactivity of Fe/ZSM-5(Albemarle), and the deactivated catalyst could be only partially regenerated. Configurations of the reactor influenced the hydrodynamic performance significantly in a cold model internal circulating fluidized bed (ICFB) reactor. For all configurations investigated, the high gas bypass ratio from the annulus to draft tube (RAD) and low draft tube to annulus gas bypass ratio (RDA) were observed, with the highest RDA associated with the conical distributor which showed the flexible and stable operation over a wide range of gas velocities. Solids circulation rates increased with the increase of gas velocities both in the annulus and the draft tube. Gas bypass was also studied in a hot model ICFB reactor. The results showed that the orientation of perforated holes on the conical distributor could be adjusted to reduce RAD and/or enhance RDA. Coarse Fe/ZSM-5(PUC) and fine Fe/ZSM-5(Albemarle) catalysts were used in an ICFB and a conventional bubbling fluidized bed to test the NOx reduction performance. Coarse Fe/ZSM-5(PUC) catalyst showed poor catalytic activity, while fine Fe/ZSM-5(Albemarle) catalyst exhibited promising NOx reduction performance and strong inhibiting ability to the negative impact of excessive O₂ in the ICFB reactor, proving that the adsorption-reduction two-zone reactor is effective for the NOx removal from oxygen-rich combustion flue gases.

The legislation has forced the vehicle industry to reduce tail-end emissions. The air pollutant nitrogen oxide (NOX) has been shown to have a negative impact on human health and the environment. One of the key technologies to reduce the levels of NOX emitted from a vehicle is by implementing an after-treatment system. The after-treatment system includes catalysts, a particle filter and an evaporation system. In the evaporation system a liquid jet containing a urea-water solution known as AdBlue is injected into the hot exhaust gases to evaporate into gaseous ammonia NH3 and water H2O. Then NH3 enters the Selective Catalytic Reduction (SCR) catalyst where it chemically reacts with NOX to form N2 and H2O. Problems can arise if an excessive amount of AdBlue is injected and a fluid film is formed on evaporation surfaces. At certain operating conditions the fluid film can crystallise and form solid deposits. The solid deposits can cause high back-pressure, material deterioration and ammonia slip. This project is done in collaboration with Scania CV AB. Scania is a world-leading manufacturer of heavy-duty vehicles, busses and engines. Scania works continuously to develop new simulation methods to capture the complex phenomena of AdBlue spray, wall film dynamics and risk of solid deposits, to use in the development process of new components. The aim of this project is to implement and evaluate a new method to predict the risk of crystallisation of urea (AdBlue) using the software Star-CCM+. Two different geometries are studied, a test rig and a Scania silencer. Different operating conditions, parameter settings and a speed-up method are analysed. During the project a base-line model has been created and the results have been compared with measurement results and the software AVL Fire. The results on the test rig show the effect of altering the mesh and important model parameters. Injected particles are grouped into parcels with the same properties. The number of parcels is a crucial factor for the wall film formation and should be sufficiently high to get a statistical representation of the droplet size distribution. The results from the real silencer show strong evaporation and thin wall film formation with the suggested method. The method is shown to be stable and the software is user-friendly. A speed-up method was investigated to decrease the computational time. The computational time was reduced by a factor 20. The outcome of this project is a guide for set-up of AdBlue spray and wall film simulations. Recommendations to future work includes further validation of the settings, investigation of the evaporation rate and droplet size distribution and the application to other cases. The next step is also to tune the critical thresholds for deposit risk assessment.
Lagstiftning har tvingat fordonstillverkare att minska avgasutsläppen. Luftföroreningen kväveoxid (NOX) har visat sig ha en negativ inverkan på människors hälsa och på miljön. En viktig teknik för att minska utsläppen av NOX ¨ar att implementera ett efterbehandlingssystem. Efterbehandlingssystemet tar hand om avgaserna genom substrat, filter och ett förångningssystem. I förångningssystemet sprutas en urea-vattenlösning, som kallas AdBlue, in i de heta avgaserna där den förångas till ammoniak NH3 och vatten H2O. Ammoniakgasen leds därefter in till SCR katalysatorn där den kemiskt reagerar med NOX och bildar kvävgas N2 och vattenånga. Problem kan uppstå om fel mängd AdBlue sprutas in, då kan vätska byggas upp på förångsningsytor, kristallisera och bilda avlagringar. Avlagringarna kan bygga upp en solid klump som kan orsaka ett högt mottryck, nedbrytning av material och ammoniakslip. Detta arbete är ett samarbete med Scania CV AB som är en världsledande producent av lastbilar, bussar och motorer. Scania arbetar kontinuerligt med att utveckla nya simuleringsvertyg för att beskriva uppkomsten av Urea avlagringar för att använda i utvecklingen av nya komponenter. Syftet med detta arbete är att implementera och utvärdera en ny metod för att prediktera klump mha simuleringsverktyget Star-CCM+. Två olika geometrier är använd i arbetet: en testrigg och en av Scanias ljuddämpare. Olika driftspunkter, parametrar och en uppsnabbad metod är studerade. Under projektets gång har en modell byggts upp och jämförts med mätningar och simuleringar från programvaran AVL Fire. Resultatet från simuleringarna på testriggen visar effekten av att variera olika parametrar. Partiklarna som sprutas in i systemet är grupperade i paket med liknande egenskaper. Antalet paket påverkar uppbyggnaden av väggfilm och det rekommenderas att denna parameter hålls hög för att statistiskt beskriva droppfördelningen av partiklar. Resultaten på ljuddämparen visar en stark förångning och en tunn väggfilm för samtliga driftspunkter. Den implementerade metoden har visat sig vara stabil och användarvänlig. En uppsnabbad metod har utvärderats för att minska beräkningstiden. Beräkningstiden kunde minskas med en faktor 20. Resultatet av arbetet är en guide för hur metoden implementeras och bör användas. Rekommendationer till framtida arbete är en fortsatt undersökning av parametrar, utvärdering av förångningsmodellen, validering av droppstorleksfördelningen och tillämpningen på andra geometrier. Nästa steg i utvecklingen skulle vara att kalibrera tröskelvärden för prediktering av klump.

Biological nutrient removal is used as an indicator of SBR performance at nine different SBRplants operated for a long period at low water temperatures (5 – 10oC). Typically needed aeratedSRT (Solids Residence Time) for complete nitrification is found to be in the range of 6 – 10 days.Biological phosphorus removal has been found to take place at 5oC. The specific nitrification and denitrification rates (g N/kg VSS/h) have been found to besubstantially higher than those found in design recommendations. At temperatures < 10 oC thenitrification rates have been found up to 4 g Nox/kg VSS/h. It has also been possible to establish a relation between the COD/N ratio and the nitrificationrate, showing that the rate increases to high rates when the ratio decreases. Enhanced biological phosphorus removal has been demonstrated at two different plants even atlow water temperatures 5 – 7 oC. Efficient biological nitrogen removal and phosphorus removal has been demonstrated at bothlow water temperatures and in presence of very high Chromium concentrations in inlet water, upto 20 mg Cr/l. The plants operated with a short fill time in comparison with the total cycle time for the SBRprocess have all demonstrated good sludge settling properties, suggesting that the SBR processmay incorporate a good sludge selection performance. Once a flexible operation strategy has been installed (in most cases through PLC systems) it hasbeen possible to meet load variations to maintain good treatment results. This has been found tobe true for most of the plants included in the thesis. Finally, a modified way to assess the energy efficiency for the system is analysed and suggested.Instead of using the traditional ratio kWh/kg BODremoved the use of kWh/kg OCPremoved as a basisfor energy efficiency is used as a far more relevant efficiency measurement.
QC 20100803

Doctor of Philosophy
Department of Civil Engineering
Kyle A. Riding
Finely ground glass has the potential for pozzolanic reactivity and can serve as a supplementary cementitious material (SCM). Glass reaction kinetics depends on both temperature and glass composition. Uniform composition, amorphous nature, and high silica content of glass make ground glass an ideal material for studying the effects of glass type and particle size on reactivity at different temperature. This study focuses on how three narrow size ranges of clear and green glass cullet, 63–75 [mu]m, 25–38 [mu]m, and smaller than 25 [mu]m, as well as combination of glass types and particle sizes affects the microstructure and performance properties of cementitious systems containing glass cullet as a SCM. Isothermal calorimetry, chemical shrinkage, thermogravimetric analysis (TGA), quantitative analysis of X-ray diffraction (XRD), and analysis of scanning electron microscope (SEM) images in backscattered (BS) mode were used to quantify the cement reaction kinetics and microstructure. Additionally, compressive strength and water sorptivity experiments were performed on mortar samples to correlate reactivity of cementitious materials containing glass to the performance of cementitious mixtures. A recently-developed modeling platform called “[mu]ic the model” was used to simulated pozzolanic reactivity of single type and fraction size and combined types and particle sizes of finely ground glass. Results showed that ground glass exhibits pozzolanic properties, especially when particles of clear and green glass below 25 [mu]m and their combination were used at elevated temperatures, reflecting that glass cullet is a temperature-sensitive SCM. Moreover, glass composition was seen to have a large impact on reactivity. In this study, green glass showed higher reactivity than clear glass. Results also revealed that the simultaneous effect of sizes and types of glass cullet (surface area) on the degree of hydration of glass particles can be accounted for through a linear addition, reflecting that the surface area would significantly affect glass cullet reactivity and that the effects of SCM material interaction on reaction kinetics were minimal. However, mechanical properties of cementitious systems containing combined glass types and sizes behaved differently, as they followed the weaker portion of the two particles. This behavior was attributed to the pores sizes, distruibution, and connectiity. Simulations of combined glass types and sizes showed that more work on microstructural models is needed to properly model the reactivity of mixed glass particle systems.

Parkinson's disease (PD) is a progressive neurodegenerative disorder of unknown cause that afflicts about 1.5 million Americans. The characteristic feature of PD is a deficiency of dopamine in the terminals of nigrostriatal neurons. Two enzyme systems, the neuronal form of nitric oxide synthase (nNOS) and monoamine oxidase B (MAO-B), have been linked to neurodegenerative pathways leading to PD. Several MAO-B and nNOS inhibitors have been evaluated for their neuroprotective properties in the mouse model of neurodegeneration which employs the parkinsonian inducing neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). One such compound is 7-nitroindazole (7-NI), a compound which is reported to inhibit both enzymes.

This thesis focuses on the synthesis and biological evaluation of a potential prodrug form of 7-NI and related indazolyl containing compounds which are designed to release the active drugs following a metabolic bioactivation process. These studies have led to a detailed description of the nucleophilic aromatic substitution reactions between 4-chloro-1-methylpyridinium iodide and the indazolyl reactants that were employed as the initial step in the synthesis of the target compounds. The MAO-B substrate and inhibition properties of these "prodrugs" as well as the parent indazolyl compounds were examined. The results are discussed in relation to a previously developed active site model of MAO-B.
Master of Science

The sensitivity of two operational output parameters, criticality and isotopic composition during burnup, to specific design and operational reactor parameters in a Sodium Cooled Fast Reactor, is investigated. The computational simulation tool Serpent is used. The parameters varied include Uranium enrichment, Plutonium content, rod thickness, fuel temperature, and sodium density. In burnup, the development of the fraction of fissile isotopes, isotopes used for measurements, the isotopic composition of Plutonium, and isotopes that complicate fuel reprocessing is displayed. A surrogate model, optimized for use in determining how criticality develops between data points, is used. The results are displayed as plots created in Matlab. The results are discussed, with a focus on how large an effect varying different parameters have on different outputs related to the reactor's operation. It is concluded that the Plutonium content has the largest effect on the isotopic composition and that, based on the performed simulations, MOX fuel is potentially safer than Zirconium alloy fuel in a practical setting.

Dissociation constants for alternate dirmcleotide substrates and competitive inhibitors suggest that the dinucleotide binding site of the Ascaris suum NAD-malic enzyme is hydrophobic in the vicinity of the nicotinamide ring. Changes in the divalent metal ion activator from Mg^2+ to Mn^2+ or Cd^2+ results in a decrease in the dinucleotide affinity and an increase in the affinity for malate. Primary deuterium and 13-C isotope effects obtained with the different metal ions suggest either a change in the transition state structure for the hydride transfer or decarboxylation steps or both. Deuterium isotope effects are finite whether reactants are maintained at saturating or limiting concentrations with all the metal ions and dinucleotide substrates used. With Cd^2+ as the divalent metal ion, inactivation of the enzyme occurs whether enzyme alone is present or is turning over. Upon inactivation only Cd^2+ ions are bound to the enzyme which becomes denatured. Modification of the enzyme to give an SCN-enzyme decreases the ability of Cd^2+ to cause inactivation. The modified enzyme generally exhibits increases in K_NAD and K_i_metai and decreases in V_max as the metal size increases from Mg^2+ to Mn^2+ or Cd^2+, indicative of crowding in the site. In all cases, affinity for malate greatly decreases, suggesting that malate does not bind optimally to the modified enzyme. For the native enzyme, primary deuterium isotope effects increase with a concomitant decrease in the 13-C effects when NAD is replaced by an alternate dinucleotide substrate different in redox potential. This suggests that when the alternate dinucleotides are used, a switch in the rate limitation of the chemical steps occurs with hydride transfer more rate limiting than decarboxylation. Deuteration of malate decreases the 13-C effect with NAD for the native enzyme, but an increase in 13-C effect is obtained with alternate dinucleotides. These suggest the presence of a secondary 13-C effect in the hydride transfer step. This phenomenon is also applicable to the modified enzyme with NAD as the substrate.

The possible effects of changes in the feeding pattern on activated sludge properties related to bioflocculation have been analyzed in lab scale sequencing batch reactors (SBR) in order to determine if these changes in effluent water quality and settling and dewatering properties are significant, so they can be considered in future studies or if they can be recommended as crucial when operating and designing wastewater treatment plants. The activated sludge process is widely used to treat wastewater from both industrial and municipal sources. Biomass from industrial facilities containing high monovalent to divalent ion content usually settles poorly, which leads to low quality effluents that fail to meet environmental requirements. Therefore, the combined effect of feeding pattern plus the addition of sodium to activated sludge reactors was studied in this experiment.

A series of SBRs were operated at different sodium concentrations that ranged from 1.5 - 15 meq/L and different feeding times that ranged from 1 minute to 4 hours. Biomass samples were taken from each reactor to study the settling and dewatering properties and effluent samples were used to analyze the amount of organic matter and exocellular polymeric substances present due to deflocculation. As expected, the changes in feeding strategies affected all of the properties measured. When the feeding time was maintained low (pulse feed) the effluent quality and settling properties were the best. As the feeding time was increased the effluent quality, settling, and dewatering properties increased suggesting that the way in which the reactors were fed affected the overall bioflocculation process. The causes of the high deflocculation observed are not well understood, but data suggest that a microbial community change could have affected exocellular biopolymers which are believed to play an important role on bioflocculation.

This research demonstrates the importance of the interaction between cation content and feeding pattern when operating a wastewater treatment plants and when reporting lab-scaled results related to settling and bioflocculation.

Master of Science

During the past decades, reactive distillation has received intensive attention due to the well known benefits of integrating distillation with reaction in a single unit. Significant capital savings, improved conversion and selectivity, avoidance of azeotropes, together with heat integration are some of the main advantages of using reactive distillation. Many applications have proven to be economically advantageous by using reactive distillation (e.g. MTBE and TAME synthesis, production of methyl-acetate, manufacture of di-isopropyl-ether, oligomerisation of linear butenes and others). Whereas there are many procedures available for the synthesis of non-reactive columns or reactive-separation systems, the synthesis of reactive distillation columns is still a challenge, due to the complexity and the high number of design parameters involved. Available conceptual design methods generally address three (or four) components and fully reactive columns, but there is still a lack of systematic conceptual design methods for more general column configurations and for multi-component systems. The aim of this work is to develop a methodology to identify promising column configurations and to obtain column design parameters (number of reactive and non-reactive stages, reflux and reboil ratios, feed condition) for a given feed mixture and a set of desired products. A new systematic design method for reactive systems reaching equilibrium allows the analysis of the impact of different configurations (fully reactive or hybrid columns) and feed policies (single- or double-feed columns) on column performance. The methodology is extended to account for kinetically-controlled reactions in synthesis and design of reactive distillation columns. Systems with two degrees of freedom (according to the Gibbs phase rule) were considered for equilibrium reactions, and ternary and quaternary systems for kinetically-controlled reactions. Reactive distillation column designs generated by the methodology are presented as illustrative examples. Their predicted performances are shown to be in good agreement with those predicted by rigorous simulation using HYSYS. The approach can easily be automated and typically generates multiple designs, allowing a design engineer to efficiently compare various design options including hybrid and fully reactive columns, single- and double-feed configurations, and different sets of operating parameters for a given column configuration. The new methodology developed in this work facilitates a stepchange in conceptual design practice, offering a systematic and easy to use tool for the synthesis and design of reactive distillation columns.

In today’s progressively urbanised society, there is an increasing need for cost-effective, environmentally sound technologies for the removal of nutrients (carbon, phosphorous, nitrogen) from polluted water. Nitrogen removal from wastewater is the focus of this thesis. Conventional nitrogen removal requires the two processes of aerobic nitrification followed by anoxic denitrification, which is driven by remaining reducing power. While most wastewaters contain a significant fraction of reducing power in the form of organic substrate, it is difficult to preserve the reducing power required for denitrification, due to the necessary preceding aerobic oxidation step. Consequently, one of the major limitations to complete N-removal in traditional wastewater treatment systems is the shortage of organic carbon substrate for the reduction of oxidised nitrogen (NO2-, NO3-), produced from nitrification. This thesis followed two main research themes that aimed to address the problem of organic carbon limitation in nitrogen removal from wastewater, by management of the oxygen supply. The first theme was the study of N-removal by simultaneous nitrification and denitrification (SND) in the novel reactor type, the sequencing batch reactor (SBR). It was aimed to increase understanding of PHB metabolism and the limiting factors of SND and then to develop a suitable on-line control strategy to manage the oxygen supply and optimise nitrogen removal by SND. The second main research theme was the application of the CANON(Completely Autotrophic Nitrogen-removal Over Nitrite) process for nitrogen removal from wastewater; a novel process that requires minimal oxygen supply and has the potential to completely circumvent the requirement for organic substrate in nitrogen removal because it is catalysed by autotrophic microorganisms – Anammox (anaerobic ammonium oxidisers) and aerobic nitrifiers. For study of the SND process, a completely automated 2 L sequencing batch reactor was developed with on-line monitoring of the dissolved oxygen concentration, pH and oxidation-reduction (ORP) potential. The SBR was operated continuously for up to 2 years and, due to its separation of different phases by time, enabled the study and optimisation of different microbial activities, including acetate uptake and conversion to PHB (feast phase), PHB hydrolysis and consumption (famine phase), nitrification and denitrification (and SND). All experimental work was performed using a mixed culture Project summary and acetate as the organic substrate. Acetate consumption and PHB production was studied under different oxygen supply rates to establish conditions that allow maximum conversion of acetate to PHB during the feast phase. Lower DO supply rates (kLa 6 – 16 h-1) resulted in preservation of a higher proportion of acetate as PHB than at higher DO supply rates (kLa 30 and 51 h-1). Up to 77 % of the reducing equivalents available from acetate were converted to PHB under O2-limitation, as opposed to only 54 % under O2-excess conditions, where a higher fraction of acetate was used for biomass growth. A metabolic model based on biochemical stoichiometry was developed that could reproduce the trends of the effect of oxygen on PHB production. Experimental findings and simulated results highlighted the importance of oxygen control during the feast phase of an SBR in preserving reducing power as PHB. To develop an oxygen management strategy for the aerobic famine phase,the effect of the dissolved oxygen (DO) concentration on SND, using PHB as the electron donor, was investigated. There was a clear compromise between the rate and the percentage of SND achieved at different DO concentrations. A DO setpoint of 1 mg L-1 was optimal for both the percentage of SND (61 %) and rate of SND (4.4 mmol N. Cmol X-1. h-1). Electron flux analysis showed that most SND activity occurred during the first hour of the aerobic famine period, when the oxygen uptake rate (due to NH4 + and PHB oxidation) was highest. Aerated denitrification ceased as soon as NH4 + was depleted. The presence of NH4 + provided an oxygen “shield”, preventing excessive penetration of oxygen into the flocs and creating larger anoxic zones for SND. PHB degradation was first order with respect to the biomass PHB concentration (dfPHB/dt = 0.19 . fPHB). The slow nature of PHB degradation made it a suitable substrate for SND, as it was degraded at a similar rate to ammonium oxidation. While DO control during the aerobic famine phase could increase nitrogen removal via SND, total N-removal in the SBR was still limited by the availability of reducing power(PHB) in the anoxic phase. The length of the aerobic phase needed to be minimised to prevent over-oxidation of PHB after NH4 + depletion. The specific oxygen uptake rate (SOUR) was found to be an effective on-line parameter that could reproducibly detect the end-point of nitrification. A simple method was developed for continuous, on-line measurement of the SOUR, which was used for automated adjustment of the aerobic phase length. Minimisation of the aerobic phase length by feedback control of the Project summary SOUR improved nitrogen removal from 69 % (without phase length control) to 86 %, during one cycle. The SOUR-aeration control technique could successfully adapt the aerobic phase length to varying wastewater types and strengths and to varying aeration conditions. The medium- and long-term effects of oxygen management on nitrogen removal was investigated by operating the SBR continuously for up to one month using DO control throughout all stages of the SBR, i.e. oxygen-limitation during the feast phase, a DO setpoint of 1 mg L-1 during the famine phase and SOUR controlled aerobic phase length. Complete oxygen management resulted in minimisation of the amount of PHB that was oxidised aerobically in each SBR cycle and caused an accumulation of cellular PHB over time. The increased availability of PHB during aeration resulted in a higher SOUR and increased N-removal by SND from 34 to 54 %. After one month of continuous SBR operation, the settling efficiency of the biomass improved from 110 mL . g-1X to less than 70 mL . g-1X and almost complete N-removal (9 %) was achieved via SND during aeration, however at a reduced rate (1.5 mmol Cmol X-1 h-1). Therefore, long-term oxygen management resulted in biomass with improved settling characteristics and a higher capacity for SND. Results of the first main research theme highlighted the importance of aeration control throughout all stages of the SBR for maximum N-removal via SND. The CANON process was investigated as an alternative to the use of conventional activated sludge for treatment of wastewaters limited by organic carbon substrate. The initial study of the CANON process was performed at the Kluyver Laboratory in Delft, the Netherlands, using an already established Anammox enrichment culture. The effect of extended periods of NH4 +-limitation on the CANON microbial populations was studied, to examine their ability to recover from major disturbances in feed composition. The CANON process was stable for long periods of time until the N-loading rate reached below 0.1 kg N m 3 day-1, when a third population of bacteria developed in the system (aerobic nitrite oxidisers), resulting in a decrease in N-removal from 92 % to 57 %. Nitrite oxidisers developed due to increased levels of oxygen and nitrite. This highlighted the requirement for oxygen control during the CANON process to prevent increased DO levels and growth of undesired microbes. To initiate the CANON process from a local source, Anammox was enriched from local activated sludge (Perth, Western Australia). FISH analysis (fluorescence in situ hybridisation) of the enriched Anammox strain showed that it belonged to the Order Planctomycetales, Project summary the same as all other identified Anammox strains, but represented a new species of Anammox. The enrichment culture was not inhibited by repeated exposure to oxygen, allowing initiation of an intermittently-aerated CANON process to achieve sustained, completely autotrophic ammonium removal (0.08 kg N m-3 day-1) for an extended period of time, without any addition of organic carbon substrate. Dissolved oxygen control played a critical role in achieving alternating aerobic and anaerobic ammonium oxidation. The main conclusion drawn from the study is the important role of oxygen management in achieving improved nitrogen removal. A careful oxygen management strategy can minimise wastage of reducing power to improve PHB-driven SND by activated sludge and can prevent major disturbances to the population balance in the CANON system. Oxygen management has the potential to reduce aeration costs while significantly improving nitrogen removal from wastewaters limited by organic carbon.

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Um dos principais problemas ambientais nos países industrializados está relacionado a liberação no meio ambiente de gases formadores de chuva ácida. A quantidade desses gases lançada para atmosfera é controlada pela legislação ambiental que vem se tornando cada vez mais restritiva. Vários são os processos aplicados a indústria capazes de remover esses contaminantes de correntes advindas de processos industriais. Dentre esses, destaca-se o processo SNOX® da Haldor Topsoe®, o qual é capaz de remover NOX e SOX de efluentes gasosos industriais, visando enquadrar a concentração desses gases dentro dos parâmetros exigidos pela legislação ambiental. A remoção desses gases é realizada por um reator constituído por dois leitos catalíticos, distintos, em série. O primeiro leito catalítico é constituído por um catalisador de estrutura monolítica, nesse ocorre a reação de redução do NOX. Enquanto que, o segundo leito é constituído por um catalisador em formato de anéis de Rashig, e nesse ocorre a oxidação do SO2. Neste trabalho foi modelado e simulado o comportamento dinâmico de um reator de abatimento de emissões atmosféricas nas condições operacionais similares a um reator de uma unidade SNOX®. Cada um dos leitos catalíticos que compõem o reator foi modelado e validado separadamente. No primeiro leito além da reação de redução do NO também considerou-se a reação de oxidação do SO2, esse modelo matemático foi simulado e avaliado nas condições operacionais apresentadas em Tronconni et al. (1998). No segundo leito catalítico do reator considerou-se apenas que a reação de oxidação do SO2 acontecia no leito, o modelo matemático do leito de oxidação foi simulado e avaliado nas condições operacionais apresentadas em Almqvist et al. (2008). Ambos os modelos apresentaram bom ajuste aos dados experimentais com erros entre 2 e 11%. Com isso, os dois modelos foram acoplados num código computacional e simulados nas condições operacionais do reator SNOX® mostrado em Schoubye e Jensen (2007). O primeiro leito catalítico teve um incremento na temperatura ao longo do reator de 9°C e a conversão de NO foi de 92%, a região de entrada do primeiro leito foi a região com maior quantidade de sítios catalíticos ocupados pela amônia. Já no segundo leito catalítico a conversão do SO2 foi de 96%. Como parte do estudo de modelagem e simulação do reator, técnicas de análise de sensibilidade global foram aplicadas, determinando-se o grau de dependência de parâmetros específicos sobre: as concentrações de NO, NH3 e SO3, no primeiro leito do reator, e as concentrações de SO2 e SO3 no segundo leito. Determinou-se que dentre os parâmetros avaliados o que teve maior influência sobre as concentrações de saída de ambos os leitos foi o comprimento do leito. A partir do modelo matemático desenvolvido neste trabalho também foram gerados dados para inferir as concentrações de NO e SO3 na saída do reator, que foi realizada através de redes neurais e máquinas de vetor de suporte. Verificou-se que a performance da estimação realizada pelas redes neurais se assemelha a das máquinas de vetor de suporte.
One of the main environmental problems in industrialized countries is related to release into the forming gas environment of acid rain. The amount of greenhouse gases released into the atmosphere is controlled by the environmental legislation, that is becoming increasingly restrictive. Several processes are applied to industry to remove these contaminants from currents resulting from industrial processes. Among these, there is the SNOX® Haldor Topsoe process, which is capable of removing NOx and SOx from industrial emissions, aiming to frame the concentration of these gases within the parameters required by environmental legislation. The removal of these gases is conducted by the process reactor consisting of two catalytic beds distinct in series. The first catalyst bed has a monolithic catalyst structure, in it occurs the reduction reaction of NOx. The second bed has a catalyst with shape of cylindrical rings, in this bed occurs the oxidation of SO2. In this work was modeled and simulated the dynamic behavior of atmospheric emissions abatement reactor in similar operating conditions to a reactor of a SNOX® unit. Each of the catalyst beds, that it make up the reactor, was modeled and validated separately. In the first bed was considered the reactions of reduction of NO and oxidation of SO2, this mathematical model was simulated and evaluated in the operating conditions presented in Tronconni et al. (1998). In the second catalytic bed was considered that only the reaction of oxidation SO2 occurred in the bed, the mathematical model of the oxidation bed was simulated and evaluated in operating conditions presented in Almqvist et al. (2008). Both models showed good fit to the experimental data with error between 2-11%. Thus, the two models had been written in computer code and simulated in reactor operating conditions SNOX® shown on Schoubye and Jensen (2007). The first catalyst bed had an increase in temperature along it of 9 ° C and the conversion of NO was 92%. In the first bed, the inlet region was the region with larger amount of catalytic sites occupied by ammonia. On the second catalytic bed, the SO2 conversion was 96,6%. As part of the modeling and simulation study for reactor the global sensitivity analysis techniques were applied aiming to determine the influence of some parameters over the concentrations of NO, NH3 and SO3 in the bed of catalytic reduction of NO and the concentration SO2 and SO3 in SO2 oxidation bed. From this study it was determined that among the evaluated parameters which it had the greatest influence on the output levels of the first reactor bed was the length of this bed. From the mathematical model developed in this paper we were also generated data to infer the concentrations of NO and SO3 in the reactor outlet, which was performed by neural networks and support vector machines. It was found that the performance of infer carried out by the neural network resembles to the performance of support vector machines.

FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico
Os sistemas de lagoas de estabilizaÃÃo, bastante presentes em aterros sanitÃrios normalmente nÃo sÃo suficientes para o atendimento aos padrÃes ambientais de descarte de lixiviado tratado em Ãguas superficiais. Este trabalho avaliou o emprego das tecnologias aerÃbias do tipo reator aerado submerso (RAS) e reator em batelada seqÃencial (RBS) como opÃÃes de pÃs-tratamento para lixiviado antigo prÃ-tratado em lagoas de estabilizaÃÃo. A coleta do lixiviado se deu na saÃda da Ãltima lagoa de estabilizaÃÃo do sistema de tratamento de lixiviado (duas anaerÃbias em sÃrie, seguidas de uma facultativa) localizadas no Aterro SanitÃrio Metropolitano Oeste (ASMOC), municÃpio de Caucaia, RegiÃo Metropolitana de Fortaleza, estado do CearÃ. Inicialmente foi realizada uma caracterizaÃÃo fÃsico-quÃmica do lixiviado efluente e verificaÃÃo do atendimento aos padrÃes de descarte. O RAS foi operado em cinco fases, sendo divididas entre esgoto sintÃtico e lixiviado, este Ãltimo testado com e sem diluiÃÃo. Avaliou-se o efeito da adiÃÃo de fonte externa de carbono, etanol, para a fase em que o reator era alimentado com lixiviado sem diluiÃÃo. O RBS foi confeccionado em acrÃlico, em formato cilÃndrico, com um volume Ãtil de 5,0L, sendo inicialmente estudado o tempo de operaÃÃo de cada ciclo de 24 horas. Posteriormente, foram avaliados no RBS os tempos totais de ciclo de 12 e 48 horas, alÃm do efeito da adiÃÃo de etanol no desempenho do reator. Os reatores foram instalados no LaboratÃrio de Saneamento (Labosan) do Departamento de Engenharia HidrÃulica e Ambiental (DEHA) da Universidade Federal do Cearà (UFC). Eles foram operados na faixa mesofÃlica, com temperatura ambiente prÃxima de 27ÂC. Em relaÃÃo ao lixiviado tratado, os valores encontrados na caracterizaÃÃo fÃsico-quÃmica confirmam a recalcitrÃncia e complexidade do lixiviado, indicando que apenas as lagoas de estabilizaÃÃo, nÃo atendem plenamente os padrÃes de descarte. A presenÃa de compostos recalcitrantes e tÃxicos no lixiviado afluente ao RAS durante um dos perÃodos de investigaÃÃo causou diminuiÃÃo na remoÃÃo de DQO, mostrando efeito inibitÃrio nos microrganismos presentes no inÃculo. Entretanto, em outra fase de investigaÃÃo, tanto o RAS quanto o RBS se mostraram eficientes e estÃveis na remoÃÃo de DQO e nitrogÃnio amoniacal, mesmo tratando lixiviado sem diluiÃÃo. A adiÃÃo de etanol como fonte externa de carbono foi benÃfica para suprir as necessidades metabÃlicas microbianas, fazendo aumentar tanto a eficiÃncia global do RAS e RBS em termos de remoÃÃo de matÃria orgÃnica (DQO), assim como na estabilidade operacional dos mesmos. O RAS e o RBS foram tambÃm bastante eficientes no processo de nitrificaÃÃo. O estudo no RBS com os tempos de ciclo de 12, 24 e 48 h revelaram que nÃo houve diferenÃa entre os tempos em relaÃÃo à remoÃÃo dos constituintes analisados, fazendo com que se considerasse 12 h como tempo Ãtimo de ciclo, de forma a minimizar os custos com volume do reator e tempo de aeraÃÃo. Como conclusÃo geral do experimento pode-se dizer que o tratamento biolÃgico aerÃbio, tanto utilizando reatores aerados submerso (RAS) quanto reatores em batelada seqÃencial (RBS), pode ser considerado uma boa alternativa para o pÃs-tratamento de lixiviado antigos provenientes de sistemas de lagoas de estabilizaÃÃo, mas ainda requer adequaÃÃes operacionais ou associaÃÃes com processos fÃsico-quÃmicos ou de oxidaÃÃo avanÃados para o enquadramento de todos os constituintes.
The system of stabilization ponds, which is often present in landfills, is usually not efficient to meet environmental standards for disposal of treated leachate on surface waters. This study evaluated the use of submerged aerated reactor (SAR) and sequencing batch reactor (SBR) as post-treatment options for old leachate pre-treated in waste stabilization ponds. The leachate collection took place at the outflow of the last stabilization pond of the treatment system (two anaerobic em series, followed by a facultative pond) located in West Metropolitan Landfill (ASMOC), Caucaia municipality, metropolitan region of Fortaleza, Cearà state. A physical-chemical characterization of the leachate effluent was performed to verify the compliance to reach disposal standards. The SAR was operated in five phases, being divided between synthetic wastewater and leachate, the latter tested with and without dilution. We evaluated the effect of adding an external carbon source, ethanol, for the phase in which the reactor was fed with leachate without dilution. SBR was made of acrylic, in a cylindrical shape with a working volume of 5.0 L and the total time cycle of 24 hours was initially studied. The total time cycles of 12 and 48 hours were also evaluated in the SBR performance, as well as the effect of adding ethanol as carbon source. The reactors were installed at the Laboratory of Sanitation (Labosan) of the Department of Hydraulic and Environmental Engineering (DEHA), Federal University of Cearà (UFC). They were operated in the mesophilic range, with temperature near 27  C. Regarding the treated leachate, the physical-chemical characterization confirmed its recalcitrance and complexity, indicating that only the stabilization ponds did not fully meet the standards of disposal. The presence of recalcitrant and toxic compounds in the leachate influent to the SAR during the investigation period decreased COD removal, showing an inhibitory effect on the microorganisms present in the inoculum. However, in another research phase, both the SAR and SBR were stable and efficient on COD and ammonia removals, even when undiluted leachate was used. The addition of ethanol as external carbon source was beneficial to meet the microbial metabolic needs, increasing both the overall efficiency of SAR and SBR in terms of organic matter removal (COD) and operational stability. The SAR and SBR were also quite efficient in the nitrification process. The study with SBR with cycle times of 12, 24 and 48 h showed no considerable difference amongst the constituent removals, so that 12 h was considered as optimal time cycle in order to minimize the costs with reactor volume and aeration time. As a general conclusion of the experiment we can say that the aerobic biological treatment, using either submerged aerated reactor (SAR) or sequencing batch reactors (SBR), can be considered a good alternative for post-treatment of old leachate pre-treated in stabilization ponds, but still requires operational adjustments and associations with physical-chemical or advanced oxidation processes for accomplish all discharge standards.

The depletion of fossil fuels together with growing environmental concerns have created incitement for developing a more energy-efficient and environmentally-friendly vehicle fleet. The development towards cleaner heavy-duty vehicles started already in the 80’s with the introduction of emission legislations. Initially, engine optimization was enough for reaching the legislated levels of emissions. However, at present engine optimization is not enough but exhaust aftertreatment has become an essential part of heavy-duty vehicles, in order to meet the emission standards. Today, the total emissions are targeted which means that there is an interest in decreasing the idling emissions as well as the emissions during operation. To reduce the overall emissions several states in the USA have introduced idling legislations. Due to the limitations in idling time alternative solutions for power generation during rests are requested. A possible alternative is a fuel cell auxiliary power unit, combining a fuel cell with a fuel reformer (FC-APU).  The focus of this thesis is the development of the fuel reformer for an FC-APU, in which the hydrogen to the fuel cell is generated from diesel in a high-temperature catalytic process. The produced hydrogen can also be used in other heavy-duty vehicle applications i.e. selective catalytic reduction of NOx (HC-SCR), where addition of hydrogen is essential for reaching high conversion at low temperatures. The effect of using hydrogen from a fuel reformer in HC-SCR is included in this work. The catalytic material development is focused on developing promoted materials with lower rhodium content but with catalytic activity comparable to that of materials with higher rhodium content. This includes evaluation and extensive characterization of both fresh and aged promoted materials. The work also includes reactor design where a micro reactor with multiple air inlets is evaluated. This work has contributed to increased knowledge of catalytic materials suitable for reforming of diesel. By changing the support material from the traditionally used alumina to ceria-zirconia, increased H2 yield was achieved. In addition, the ceria-zirconia supported material was less prone to coke. By promoting the material with cobalt or lanthanum it was possible to decrease the rhodium content by 2/3 with enhanced catalytic performance. It was also discovered that promotion with lanthanum decreased the tendency for coking even further. Additionally, the lanthanum-promoted material had higher thermal stability as well as a stable highly dispersed rhodium phase. Furthermore, the work has contributed to an increased knowledge concerning the fuel reformer’s effect on HC-SCR. The work displays clear evidence of benefits with using hydrogen-rich gas from a fuel reformer instead of pure hydrogen. The benefits are derived from the content of low molecular weight hydrocarbons present in the hydrogen-rich gas, which are strong reducing agents increasing the NOx reduction. This finding proves that fuel reforming in combination with HC-SCR is a viable option for NOx abatement.

QC 20150202

This thesis is divided into two broad categories: the synthesis and SAR of thapigargin I and related derivatives, discussed in Part A, and mechanistic studies of perovskite-mediated Suzuki reactions, discussed in Part B. Experimental procedures for both projects can be found in Part C, along with appendices and references. (Fig. 566401A) Part A delineates the successful synthesis of unnatural analogues of thapsigargin 89, 91 and 93, which were subsequently evaluated as SERCA inhibitors. The results show that unlike the related analogue 33, none of these analogues significantly inhibited SERCA. (Fig. 566401B) Degradation studies of a natural sample of thapsigargin 1 are also described. the intermediates obtained were used to probe possible reactions, conditions and protecting groups for the final steps of the total synthesis of the natural product and served to highlight problems with other synthetic routes. Discussion of how these results were successfully applied to the completion of the first total synthesis of thapsigargin can be found in Section 2. Part B describes work conducted during the first year of these graduate studies and many of the results have now been published. A battery of experiments was used to convincingly show that LaFe_0.57Co_0.38Pd_0.05O₃-mediated Suzuki reactions take place, in part at least, via solution-phase Pd intermediates, believed to desorb from the perovskite lattice during the reaction and be recaptured at the end of the cycle. A series of related structures have been evaluated as potential Suzuki catalysts and their structures and activities are critically assessed.

Els lixiviats d'abocadors urbans són aigües residuals altament contaminades, que es caracteritzen per les elevades concentracions d'amoni i el baix contingut de matèria orgànica biodegradable. El tractament dels lixiviats a través dels processos de nitrificació-desnitrificació convencionals és costós a causa de la seva elevada demanda d'oxigen i la necessitat d'addició d'una font de carboni externa. En els darrers anys, la viabilitat del tractament d'aquest tipus d'afluents per un procés combinat de nitritació parcial-anammox ha estat demostrada. Aquesta tesi es centra en el tractament de lixiviats d'abocador a través d'un procés de nitritació parcial en SBR, com un pas preparatori per a un reactor anammox. Els resultats de l'estudi han demostrat la viabilitat d'aquesta tecnologia per al tractament de lixiviats d'abocador. El treball va evolucionar des d'una escala inicial de laboratori, on el procés va ser testat inicialment, a uns exitosos experiments d'operació a llarg termini a escala pilot. Finalment, la tesi també inclou el desenvolupament, calibració i validació d'un model matemàtic del procés, que té com a objectiu augmentar el coneixement del procés.
Urban landfill leachate are highly contaminated wastewater, usually characterised by high ammonium concentrations and low biodegradable organic matter content. Treating leachate through conventional nitrification-denitrification processes is expensive due to its high oxygen demand and the requirement of a supplementary external carbon source. In recent years, the feasibility of treating such streams with a low C:N ratio by a combined partial nitritation-anammox process has been demonstrated. This thesis deals with the treatment of landfill leachate by a partial nitritation-SBR, as a preparative step for an anammox reactor. The results of the study have demonstrated the feasibility of this technology for the treatment of landfill leachate. The work evolved from initial lab-scale studies, where the process was first tested, to a successful long-term experiment at pilot-scale. In addition, the thesis also includes the development, calibration and validation of a mathematical model of the process, aiming at increasing process knowledge.

Este trabalho propõe uma metodologia para enumerar soluções, que indiquem a barra e a compensação de potência reativa necessária para o sistema elétrico sob análise, que atendam aos requisitos avaliados pela função objetivo e as restrições. Nessa alocação de compensação ótima de potência reativa, obtemos as melhores barras e configurações de potências e tecnologias de dispositivos de compensação, minimizando as perdas totais de potência ativa da rede. Em redes fracas com conversores de frequência (por exemplo, para conexão de fontes renováveis, ou interligações utilizando conversores HVDC), esta metodologia proposta busca a melhor relação de curto-circuito trifásico (SCR) no ponto de conexão do conversor de frequência, melhorando a conexão da barra de interesse. O método busca soluções para alocar um único dispositivo de compensação, e soluções alocando simultaneamente dois dispositivos. A metodologia proposta baseia-se na enumeração exaustiva das soluções, e o estudo de caso nos sistemas de 14 e 30 barras do IEEE mostrou a aplicabilidade e funcionalidade da metodologia proposta.
This work proposes a methodology to enumerate solutions, which indicate the bar and the reactive power compensation required for the electrical system under analysis, that meet the requirements evaluated by the objective function and the constraints. In this allocation of optimal compensation of reactive power, we obtain the optimal bars and technologies of compensation devices, minimizing the total losses of active power of the network. In weak networks with frequency converters (e.g. for connection of renewable sources, or interconnections using HVDC converters), the proposed methodology seeks the best threephase short-circuit (SCR) relation at the connection point, improving the connection of the new generation. The method looks for solutions to allocate a single compensation device, and solutions to allocate two devices simultaneously. The proposed methodology is based on the exhaustive enumeration of the solutions. A case study carried out in the IEEE 14 and 30 bus systems shows the applicability and performance of the proposed methodology.

En aquesta tesis s'ha desenvolupat un sistema de control capaç d'optimitzar el funcionament dels Reactors Discontinus Seqüencials dins el camp de l'eliminació de matèria orgànica i nitrogen de les aigües residuals. El sistema de control permet ajustar en línia la durada de les etapes de reacció a partir de mesures directes o indirectes de sondes. En una primera etapa de la tesis s'ha estudiat la calibració de models matemàtics que permeten realitzar fàcilment provatures de diferents estratègies de control. A partir de l'anàlisis de dades històriques s'han plantejat diferents opcions per controlar l'SBR i les més convenients s'han provat mitjançant simulació. Després d'assegurar l'èxit de l'estratègia de control mitjançant simulacions s'ha implementat en una planta semi-industrial. Finalment es planteja l'estructura d'uns sistema supervisor encarregat de controlar el funcionament de l'SBR no només a nivell de fases sinó també a nivell cicle.
In this Thesis a control system has been developed which permits optimizing the performance of the Sequencing Batch Reactors (SBR) within the field of organic matter and nitrogen removal from the wastewater. This control system is based on the on-line adjustment of the length of the reaction phases using directly or indirectly the data acquired from the sensors. In a first stage of the Thesis the calibration of the activated sludge models is studied what permits obtaining models for testing different operating and control strategies. From the analysis of historical data several options for controlling the SBR are obtained and most suitable is tested using a simulation approach. Afterwards, the control strategy is implemented in a semi-industrial plant obtaining promising results. Finally, a proposal for a supervisory control system is presented which can be in charge of controlling the performance of the SBR not only at a phase level but also at cycle level.

Actualment, la legislació ambiental ha esdevingut més restrictiva pel que fa a la descàrrega d'aigües residuals amb nutrients, especialment en les anomenades àrees sensibles o zones vulnerables. Arran d'aquest fet, s'ha estimulat el coneixement, desenvolupament i millora dels processos d'eliminació de nutrients.
El Reactor Discontinu Seqüencial (RDS) o Sequencing Batch Reactor (SBR) en anglès, és un sistema de tractament de fangs actius que opera mitjançant un procediment d'omplerta-buidat. En aquest tipus de reactors, l'aigua residual és addicionada en un sol reactor que treballa per càrregues repetint un cicle (seqüència) al llarg del temps. Una de les característiques dels SBR és que totes les diferents operacions (omplerta, reacció, sedimentació i buidat) es donen en un mateix reactor.
La tecnologia SBR no és nova d'ara. El fet, és que va aparèixer abans que els sistema de tractament continu de fangs actius. El precursor dels SBR va ser un sistema d'omplerta-buidat que operava en discontinu. Entre els anys 1914 i 1920, varen sorgir certes dificultats moltes d'elles a nivell d'operació (vàlvules, canvis el cabal d'un reactor a un altre, elevat temps d'atenció per l'operari...) per aquests reactors. Però no va ser fins a finals de la dècada dels '50 principis del '60, amb el desenvolupament de nous equipaments i noves tecnologies, quan va tornar a ressorgir l'interès pels SBRs. Importants millores en el camp del subministrament d'aire (vàlvules motoritzades o d'acció pneumàtica) i en el de control (sondes de nivell, mesuradors de cabal, temporitzadors automàtics, microprocessadors) han permès que avui en dia els SBRs competeixin amb els sistemes convencional de fangs actius.
L'objectiu de la present tesi és la identificació de les condicions d'operació adequades per un cicle segons el tipus d'aigua residual a l'entrada, les necessitats del tractament i la qualitat desitjada de la sortida utilitzant la tecnologia SBR. Aquestes tres característiques, l'aigua a tractar, les necessitats del tractament i la qualitat final desitjada determinen en gran mesura el tractament a realitzar. Així doncs, per tal d'adequar el tractament a cada tipus d'aigua residual i les seves necessitats, han estat estudiats diferents estratègies d'alimentació.
El seguiment del procés es realitza mitjançant mesures on-line de pH, OD i RedOx, els canvis de les quals donen informació sobre l'estat del procés. Alhora un altre paràmetre que es pot calcular a partir de l'oxigen dissolt és la OUR que és una dada complementària als paràmetres esmentats.
S'han avaluat les condicions d'operació per eliminar nitrogen d'una aigua residual sintètica utilitzant una estratègia d'alimentació esglaonada, a través de l'estudi de l'efecte del nombre d'alimentacions, la definició de la llargada i el número de fases per cicle, i la identificació dels punts crítics seguint les sondes de pH, OD i RedOx.
S'ha aplicat l'estratègia d'alimentació esglaonada a dues aigües residuals diferents: una procedent d'una indústria tèxtil i l'altra, dels lixiviats d'un abocador. En ambdues aigües residuals es va estudiar l'eficiència del procés a partir de les condicions d'operació i de la velocitat del consum d'oxigen. Mentre que en l'aigua residual tèxtil el principal objectiu era eliminar matèria orgànica, en l'aigua procedent dels lixiviats d'abocador era eliminar matèria orgànica i nitrogen.
S'han avaluat les condicions d'operació per eliminar nitrogen i fòsfor d'una aigua residual urbana utilitzant una estratègia d'alimentació esglaonada, a través de la definició del número i la llargada de les fases per cicle, i la identificació dels punts crítics seguint les sondes de pH, OD i RedOx.
S'ha analitzat la influència del pH i la font de carboni per tal d'eliminar fòsfor d'una aigua sintètica a partir de l'estudi de l'increment de pH a dos reactors amb diferents fonts de carboni i l'estudi de l'efecte de canviar la font de carboni.
Tal i com es pot veure al llarg de la tesi, on s'han tractat diferents aigües residuals per a diferents necessitats, un dels avantatges més importants d'un SBR és la seva flexibilitat.
Actualmente, la legislación ambiental se ha convertido más restrictiva por lo que concierne al vertido de aguas residuales con nutrientes, especialmente en las llamadas áreas sensibles o zonas vulnerables. A partir de este hecho, se ha estimulado el conocimiento, desarrollo y mejora de los procesos de eliminación de nutrientes.
El Reactor Discontinuo Secuencial (RDS) o Sequencing Batch Reactor (SBR) en inglés, es un sistema de tratamiento de fangos activados que opera mediante un procedimiento de llenado-vaciado. En este tipo de reactores, el agua residual es adicionada en un solo reactor que trabaja por cargas repitiendo un ciclo (secuencia) a lo largo del tiempo. Una de les características de los SBR es que todas las diferentes operaciones (llenado, reacción, sedimentación y vaciado) se dan en el mismo reactor.
La tecnología SBR no es nueva. De hecho, apareció antes que el sistema de tratamiento continuo de fangos activados. El precursor de los SBR fue un sistema de llenado-vaciado que operaba en discontinuo. Entre los años 1914 y 1920, surgieron ciertas dificultades muchas de ellas a nivel de operación (válvulas, cambios de caudal de un reactor a otro, elevado tiempo de atención por parte del operario...) para estos reactores. Pero no fue hasta finales de la década de los '50 principios de los '60, con el desarrollo de los nuevos equipamientos y las nuevas tecnologías, cuando volvió a resurgir el interés en los SBRs. Importantes mejoras en el campo de los suministro de aire (válvulas motorizadas o de acción neumática) y en el de control (sondas de nivel, medidores de caudal, temporizadores automáticos, microprocesadores) han permitido que hoy en día los SBRs compitan con los sistemas convencionales de fangos activados.
El objetivo de la presente tesis es la identificación de las condiciones de operación adecuadas para un ciclo según el tipo de agua residual en la entrada, las necesidades del tratamiento y la calidad deseada de la salida utilizando la tecnología SBR. Estas tres características, el agua a tratar, las necesidades del tratamiento y la calidad final deseada determinan en gran medida el tratamiento a realizar. Así pues, para poder adecuar el tratamiento a cada tipo de agua residual y a sus necesidades, han sido estudiados diferentes estrategias de alimentación.
El seguimiento de los cambios de las medidas en línea de pH, OD y RedOx proporciona información sobre el proceso. A su vez, otro parámetro que se puede calcular a partir del OD es la OUR que también da información del proceso.
Se han evaluado las condiciones de operación para eliminar nitrógeno de una agua residual sintética utilizando una estrategia de alimentación escalonada, a partir del estudio del efecto del número de alimentaciones, la definición de la longitud y el número de fases por ciclo, y la identificación de los puntos críticos siguiendo las sondas de pH, OD y RedOx.
Se ha aplicado la estrategia de alimentación escalonada a dos aguas residuales diferentes: una procedente de una industria textil y la otra, de los lixiviados de un vertedero. En las dos aguas residuales se estudió la eficiencia del proceso a partir de las condiciones de operación y de la velocidad de consumo de oxigeno. Mientras que en el agua residual textil el principal objetivo era eliminar materia orgánica, en el agua procedente de los lixiviados del vertedero era eliminar materia orgánica y nitrógeno.
Se han evaluado las condiciones de operación para eliminar nitrógeno y fósforo de una agua residual urbana utilizando una estrategia de alimentación escalonada, a partir del estudio de la definición de la longitud y el número de fases por ciclo, y la identificación de los puntos críticos siguiendo las sondas de pH, OD y RedOx.
Se han analizado la influencia del pH y la fuente de carbono para eliminar fósforo de un agua sintética a partir del estudio del incremento de pH en dos reactores con diferentes fuentes de carbono y el estudio del efecto de cambiar la fuente de carbono.
Como se puede apreciar a lo largo de la tesis, donde se han tratado diferentes aguas residuales para a diferentes necesidades, una de las ventajas más importantes de los SBR es su flexibilidad.
Nowadays, environmental legislation has become more restricted in the nutrient wastewater discharge, especially in the sensitive areas and vulnerable zones. So, many studies have been stimulated on the understanding, developing and improving the biological nutrient removal processes.
The Sequencing Batch Reactor (SBR) is a fill-and-draw activated sludge system for wastewater treatment. In this system, wastewater is added to a single reactor which operates in a batch treatment mode repeating a cycle (sequence) continuously. All the operations (fill, react, settle and draw) are achieved in a single batch reactor.
SBR technology is not new. In fact, it precedes the use of continuous flow activated sludge technology. The precursor to this was a fill-and-draw system operated on batch, similar to the SBR. Between 1914 and 1920, many difficulties were associated with operating these fill-and-draw systems, most resulting from the process valving required to switch flow from one reactor to another, operator attention required. Interest in SBRs was revived in the late 1950s and early 1960s, with the development of new equipment and technology. Improvements in aeration devices (i.e. motorized valves, pneumatically actuated valves) and controls (level sensors, flowmeters, automatic timers, microprocessors) have allowed SBRs to successfully compete with conventional activated sludge systems.
The aim of this thesis consists in the identification of suitable operation conditions for a cycle according to kind of influent wastewater, treatment requirements and effluent quality using a SBR technology. The influent wastewater, treatment requirements and effluent quality desire determinate in great measure the treatment to realize. So, different studies have been carried out in order to obtain a suitable treatment for each wastewater and requirement using a step-feed strategy.
By means of on-line pH, DO and ORP measurements are possible follow the status of the process. At the same time another parameter, that complements all these, is the OUR calculated through DO dada.
Evaluation the operation conditions for nitrogen removal using a step-feed strategy for a synthetic wastewater through the study of the effect of number of filling events, the definition of the length and number of phases for a cycle, and the identification of the critical points following the pH, DO and ORP sensors.
Application of the step-feed strategy in two different industrial wastewaters: textile wastewater and landfill leachate wastewater. In both wastewaters, the efficiency has been studied through the operational conditions and oxygen uptake rate. While in the textile wastewater the main objective was only organic matter removal, in the landfill leachate wastewater was carbon and nitrogen removal.
Evaluation of the operation conditions for nitrogen and phosphorus removal using a step-feed strategy for an urban wastewater through, the definition of the number and length of phases for a cycle, and the identification of the critical points following the pH, DO and ORP sensors.
Influence of pH and carbon source in phosphorus removal using synthetic wastewater through the study of pH increase in two different carbon sources and the effect of change of carbon source.
As it can be observed in this thesis, where it is treated different wastewaters for different requirements, one of the main advantages of the SBR is its flexibility.

In the last decades, the awareness of environmental issues has increased in society considerably. There is an increasing need to improve the effluent quality of domestic wastewater treatment processes. This thesis describes the application of the Sequencing Batch Reactor (SBR) technology for Biological Nutrient Removal (BNR) from the wastewater. In particular, the work presented evolves from the nitrogen removal to the biological nutrient removal (i.e. nitrogen plus phosphorous removal) with special attention to the operational strategy design, the identification of possible reactor cycle controls or the influent composition related to the process efficiency. In such sense, also the use of ethanol as an external carbon (when low influent Carbon:Phosphorus (C:P) or Carbon:Nitrogen (C:N) ratios are presented) are studied as an alternative to maintain the BNR efficiency.

Thesis (MTech (Civil Engineering))--Cape Peninsula University of Technology, 2016.
The addition of certain fillers and additives in conventional concrete is imperative for improving its rheological properties. The effect of additives, namely limestone (LS) and superplasticisers (SP), on the hydration kinetics of self-compacting concrete (SCC) was investigated on cement paste scale. These additives interact mostly with cement paste, since aggregates are considered to be inert materials. An understanding of the effect of these additives on the hydration kinetics of cement paste is paramount to the design of an SCC with excellent properties. Four CEM I 52.5N Portland cements from one supplier but produced at different factories, LS and two types of SP, were used in this research. The hydration kinetics were evaluated by monitoring the elastic modulus growth of the cement pastes. Different coefficients of the self-acceleration kinetics equation – the self-acceleration constant, characteristic time and real time of hydration – were used to establish the effect of different concentrations of SP with and without the optimum concentration of limestone (30%) on the hydration kinetics of cement pastes. As far as can be ascertained, this is the first time the rheokinetic model has been used to describe the initial hydration of SCC paste.

This thesis presents results obtained during 2007/08 in the course of doctoral research into attitudes towards linguistic variation in England and Austria and is based in part on a study by Lees (2000). In this project attitudes amongst British and Austrian informants towards low-prestige ('dialect') and high-prestige varieties are investigated on the basis of assumptions made about speakers of these varieties. The data are collected by means of the 'matched-guise technique', whereby informants listen to a number of recordings of low and high-prestige varieties and note their reactions on the basis of a selection of traits using a semantic differential. In this way the research aims to ascertain whether a pattern emerges, where the informants' perception of the guises is influenced by the prestige of the spoken variety. The results in England and in Austria are compared in order to determine similarities and differences in language attitudes towards low and high-prestige varieties in the two countries. Some results presented here correspond to certain social expectations, with high-prestige speakers being associated with better-paid employment and a better education. Other results, though, are less predictable, as where, for example, the female informants in England and in Austria judge the speakers more positively than the male informants, regardless of the prestige of the speaker's variety. In any case, there is evidence from both countries of the informants' evaluations of the speaker being influenced by their associations of the speaker's variety with that speaker's social status. The data also indicate that the social status of speakers in England is judged to a greater extent on the basis of their spoken variety than is the case in Austria, where speakers are more used to switching freely between points on the standard-dialect continuum and are consequently less judgemental in their perception of a speaker based purely on the evidence of their spoken variety.

Biological nutrient removal has been studied and applied for decades in order to remove nitrogen and phosphorus from wastewater. However, more anthropogenic uses and the continued demand for water have forced the facilities to operate at their maximum capacity. Therefore, the goal of this thesis is to obtain more compact systems for nutrient removal from domestic wastewater. In this sense, optimization and long-term stabilization of high volume exchange ratios reactors, treating higher volumes of wastewater, have been investigated. With the same target, aerobic granular sludge was proposed as a reliable alternative to reduce space and increase loading rates in treatment plants. However, the low organic loading rate from low-strength influents (less than 1 Kg COD•m-3d-1) results in slower granular formation and a longer time to reach a steady state. Because of that, different methodologies and operational conditions were investigated in order to enhance granulation and nutrient removal from domestic wastewater.
L’estudi de l’eliminació biològica de nutrients s’ha dut a terme durant dècades. Tot i això, la influencia de l’home i l’augment de la demanda d’aigua han forçat a les instal•lacions a treballar a la seva capacitat màxima. Així, l’objectiu de la tesi és obtenir sistemes més compactes per a l’eliminació de nutrients de les aigües residuals. En aquest sentit, s’ha investigat l’optimització i estabilització de reactors amb alts volums d’intercanvi, tractant més aigua. Amb el mateix objectiu, el fang granular aeròbic va ser proposat com una alternativa fiable per tal de reduir l’espai i incrementar les càrregues de les depuradores. Tot i això, la granulació amb influents de baixa càrrega (menors a 1 Kg dQO•m-3d-1) resulta més lenta i més dificultosa alhora d’obtenir l’estat estacionari. Per aquesta raó es van investigar diferents metodologies i condicions d’operació per tal de millorar la granularció i l’eliminació de nutrients de les aigües urbanes.

By the end of the twentieth century, there were many secessionist groups, but, the move towards Taiwanese secessionism has arguably been the most significant of these. It triggered the 1996 Taiwan Strait Crisis, which resulted in a historical military confrontation between Mainland China and the US. As will be shown, from 1988 to 2000, Lee Teng-hui, as president of Taiwan, manipulated the political Cross-Straits relationship to promote what was ultimately a secessionist policy. This caused Mainland China to react strongly and triggered sharp tension between Taiwan and Mainland China. This thesis considers what motivated Lee Teng-hui to implement a secessionist Cross-Straits policy and why he supported unification while adopting a substantive secessionist policy. It looks at how he was able to instigate Taiwanese hostility towards Mainlanders, to transform the hostility into a sense of Taiwanese national identity and ultimately into Taiwanese secessionist ideology. A historical approach was used in exploring the origins of secessionism, and descriptive and analytical methods to review systematically and comprehensively political developments in the ROC and its civil war, and to study Lee Teng-hui’s life; the national identity of Taiwan and Mainland China; the implementation of Lee Teng-hui’s political Cross-Straits policy; and the reaction of Mainland China. The study showed that the main cause of Taiwanese secessionism was ethnic conflict between Taiwanese and Mainlanders. It originated from the 228 Incident of 1947, in which Mainlander-led troops slaughtered many Taiwanese. Soon after, the Mainlander-led government fled to Taiwan from Mainland China, and many Taiwanese (including Mainlanders) were killed during the State of Emergency in the 1950s and 1960s. Since the Mainlander-led government fled to Taiwan in its original central government form, the Mainlander élite occupied key positions in the government during the 1950s and 1960s. It resulted in unfair power-sharing for Taiwanese, and caused the Taiwanese élite to believe that they had to establish their own government (nation). Lee Teng-hui had participated in the CCP and had been under political surveillance by the Mainlander-led government for over twenty years. He weathered these political difficulties, but by reasonable inference, there was a close relationship between the political oppression by the Mainlander-led government and his secessionist political Cross-Straits policy. Because Taiwanese residents were indoctrinated by Chiang Ching-kuo and his father, Chiang Kai-shek’s administration for about 40 years, Chinese ideology was dominant and Lee Teng-hui initially paid lip-service to Cross-Strait unification whilst working towards secessionism as reflected in the Chingdao-Lake Incident (1994); the private dialogue between Lee Teng-hui and Shiba Ryotaro (1994); the address at Cornell University (1995); and his two-state theory (1999). However, due to strong pressure from Mainland China, he did not reach his secessionist goal during his presidential term (1988-2000). In conclusion, this thesis shows that Taiwan Island’s geopolitical importance is at the heart of the US’ support for Taiwan’s secession from the Mainland. Therefore, Lee’s secessionist Cross-Strait policy aside, US national interests lie in containing Mainland China and it has, therefore, always played an important role in the secessionist issue and always will. From the perspective of Mainland China, either in terms of nationalism or national security, Taiwan’s secession is a life-and-death issue. If Taiwanese authorities were to declare independence, the only option for Mainland China would be to launch a unification war. For the US, Taiwan is only a pawn that it uses to contain Mainland China. Therefore, in the Cross-Strait issue, the US has more options than Mainland China, namely, to use military intervention in the future to deter Chinese unification or to decide to share common peaceful international relations with Mainland China by accepting Cross-Strait unification.
Thesis (DPhil (International Relations))--University of Pretoria, 2004.
Political Sciences
unrestricted

The stress corrosion cracking (SCC) of components which are fabricated from austenitic stainless steel has been observed in the primary circuit of pressurised water reactors (PWR). In recent years it has become an increasing concern that cold work can induce susceptibility to SCC in these materials, even when exposed to good-quality flowing coolant. Laboratory studies which were launched in response to this observation have confirmed that SCC susceptibility is enhanced by cold work. The intention of this study is therefore to investigate the link between the effects of cold work on the material and the susceptibility to SCC. The investigation has been conducted on a grade 304 austenitic stainless steel. Characterisation of the microstructure and mechanical properties has been carried out in the annealed condition, and following cold rolling to a reduction in thickness of 20 %. The cold rolled material has then been subjected to SCC tests in simulated PWR primary circuit coolant. Two types of test were utilised: slow strain rate tests (SSRTs) were carried out in order to investigate the initiation of cracks from a smooth surface and constant load tests using pre-cracked specimens were used to investigate the crack propagation behaviour. In both types of test the SCC produced was predominantly intergranular. The SSRTs revealed that the most susceptible grain boundaries separated grains which had dissimilar deformation microstructures (one grain deformed heavily by planar bands, the other more homogenously). It was also observed that initiation could occur on a grain boundary which is adjacent to an annealing twin. In both microstructural configurations the susceptibility is likely to be due to the deformation incompatibility across the failed boundary, possible indicating that shear at the boundary is important for the initiation of cracking. The crack propagation behaviour of the rolled material was particularly anisotropic; regardless of the loading direction (specimens were manufactured to allow loading along the rolling, transverse and normal plate directions) cracking was observed to occur parallel to the rolling-transverse plane. The origin of this behaviour was explored in terms of preferential alignment of the deformation microstructure and the anisotropic mechanical properties of the rolled plate. Limited transgranular cracking was also observed, which occurred along oxidised deformation bands. The results overall indicate that heterogeneous deformation between different regions of the material, and preferential alignment of the deformation microstructure are important with respect to the SCC susceptibility of the rolled material.

Thesis (Ph.D)--Biomedical Engineering, Georgia Institute of Technology, 2009.
Committee Chair: Bellamkonda, Ravi; Committee Member: Babensee, Julia; Committee Member: Butera, Robert; Committee Member: DeWeerth, Steve; Committee Member: Lee, Robert; Committee Member: McKeon, Robert. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Chalcone is an alternative name for an α,β-unsaturated carbonyl compound. The system consists of two aromatic rings linked together by a three aliphatic carbon bridge. In the last few years, chalcones and their derivatives have become one of the interesting compounds that show significant activity in reducing PrPSc levels and for this reason these types of compounds were chosen as lead compounds for this project. Different series’ of chalcones were synthesised via aldol condensation under continuous flow conditions. The first route consists of the reaction between 4-(benzyloxy)-3-methoxybenzaldehyde and different substituted acetophenones. The second route contains the indole moiety, these compounds were synthesised from the reaction between 1H-indol-6-carbaldehyde and different substituted acetophenones. A new chalcone was synthesised from 3-((1H-pyrazol-1-yl)methyl)-4-methoxybenzaldehyde which was treated with acetophenone forming the corresponding chalcone. The synthesised chalcone was then used to synthesise two types of pyrrolones containing the moiety of 5-hydroxy-pyrrolidin-2-one (γ-hydroxy-γ-lactam). Three different types of amines were used to synthesise the fourth type of chalcones. The amines were reacted with 4-flourobenzaldehyde forming the corresponding aldehydes which were treated with a variety of heterocylic ketones to produce the corresponding chalcones. Three types of bischalcones were also synthesised from the reaction between 4-(1H-pyrazol-1-yl)benzaldehyde and different ketones. Chalcones containing the quinoline moiety were synthesised in four steps starting from m-toluidine to form the aldehyde which was treated with a variety of acetophenones forming the corresponding chalcones. The ketothylinic group of the chalcones were cyclized into the corresponding pyrazolines by treating them with hydrazine monohydrate using ionic solvent under continuous flow conditions. Finally, all the synthesised chalcones and their derivatives were screened for their antiprion activity and to investigate the antiprion structure-activity relationship. Amongst 51 chalcones and their derivatives 27 compounds were found to be active as antiprion agents. The Best EC50 values were found in compounds 154 (EC50 = 0.097µM), 155 (EC50 = 0.0103 µM), 163b (EC50 = 0.1 µM), 171 (EC50 = 0.1 µM), 179 (EC50 = 0.14 µM), 180 (EC50 = 0.10 µM), 181 (EC50 = 0.54 µM), 182 (EC50 = 0.01 µM) and 183 (EC50 = 0.03 µM).

Il CP-ESFR è un progetto integrato di cooperazione europeo sui reattori a sodio SFR realizzato sotto il programma quadro EURATOM 7, che unisce il contributo di venticinque partner europei. Il CP-ESFR ha l'ambizione di contribuire all'istituzione di una "solida base scientifica e tecnica per il reattore veloce refrigerato a sodio, al fine di accelerare gli sviluppi pratici per la gestione sicura dei rifiuti radioattivi a lunga vita, per migliorare le prestazioni di sicurezza, l'efficienza delle risorse e il costo-efficacia di energia nucleare al fine di garantire un sistema solido e socialmente accettabile di protezione della popolazione e dell'ambiente contro gli effetti delle radiazioni ionizzanti. " La presente tesi di laurea è un contributo allo sviluppo di modelli e metodi, basati sull’uso di codici termo-idraulici di sistema, per l’ analisi di sicurezza di reattori di IV Generazione refrigerati a metallo liquido. L'attività è stata svolta nell'ambito del progetto FP-7 PELGRIMM ed in sinergia con l’Accordo di Programma MSE-ENEA(PAR-2013). Il progetto FP7 PELGRIMM ha come obbiettivo lo sviluppo di combustibili contenenti attinidi minori 1. attraverso lo studio di due diverse forme: pellet (oggetto della presente tesi) e spherepac 2. valutandone l’impatto sul progetto del reattore CP-ESFR. La tesi propone lo sviluppo di un modello termoidraulico di sistema dei circuiti primario e intermedio del reattore con il codice RELAP5-3D© (INL, US). Tale codice, qualificato per il licenziamento dei reattori nucleari ad acqua, è stato utilizzato per valutare come variano i parametri del core del reattore rilevanti per la sicurezza (es. temperatura di camicia e di centro combustibile, temperatura del fluido refrigerante, etc.), quando il combustibile venga impiegato per “bruciare” gli attinidi minori (isotopi radioattivi a lunga vita contenuti nelle scorie nucleari). Questo ha comportato, una fase di training sul codice, sui suoi modelli e sulle sue capacità. Successivamente, lo sviluppo della nodalizzazione dell’impianto CP-ESFR, la sua qualifica, e l’analisi dei risultati ottenuti al variare della configurazione del core, del bruciamento e del tipo di combustibile impiegato (i.e. diverso arricchimento di attinidi minori). Il testo è suddiviso in sei sezioni. La prima fornisce un’introduzione allo sviluppo tecnologico dei reattori veloci, evidenzia l’ambito in cui è stata svolta questa tesi e ne definisce obbiettivi e struttura. Nella seconda sezione, viene descritto l’impianto del CP-ESFR con attenzione alla configurazione del nocciolo e al sistema primario. La terza sezione introduce il codice di sistema termico-idraulico utilizzato per le analisi e il modello sviluppato per riprodurre l’impianto. Nella sezione quattro vengono descritti: i test e le verifiche effettuate per valutare le prestazioni del modello, la qualifica della nodalizzazione, i principali modelli e le correlazioni più rilevanti per la simulazione e le configurazioni del core considerate per l’analisi dei risultati. I risultati ottenuti relativamente ai parametri di sicurezza del nocciolo in condizioni di normale funzionamento e per un transitorio selezionato sono descritti nella quinta sezione. Infine, sono riportate le conclusioni dell’attività.

This thesis is a follow up on "SPARC fast reactor design: Design of two passively metal-fuelled sodium-cooled pool-type small modular fast reactors with Autonomous Reactivity Control" by Tobias Lindström (2015). In this thesis the two reactors designed by Lindström in said thesis were evaluated. The goal was to determine the reactors ability to load follow as well as the burnup of the neutron absorber used in the passive control system. To be able to determine the dynamic behaviour of the reactors the reactivity feedbacks of the cores were modelled using Serpent, a Monte Carlo simulation software for 3D neutron transport calculations. These feedbacks were then implemented into a dynamic simulation of the core, primary and secondary circulation and steam generator. The secondary circulation and feedwater flow were used to regulate steam temperature and turbine power. The core was left at constant coolant flow and no control rods were used. The simulations showed that the reactor was able to load follow between 100 % and 40 % of rated power at a speed of 6 % per minute. It was also shown that the reactor could safely adjust its power between 100 % and 10 % of rated power suggesting that load following is possible below 40 % of rated power but at a lower speed. Finally the reactors were allowed compensate for the variations in a week of the Latvian wind power production in order to show one possible application of the reactor.

Mestrado em Biotecnologia
Polyhydroxyalkanoates (PHA) emerge as a promising alternative to the conventional plastics due to its biodegradability, biocompatibility and thermochemical properties. Several strategies have been studied in order to decrease PHA production costs and enlarge their commercialization, such as the use of pre-treated renewable substrates and the development of economically and environmentally sustainable extraction procedures. The first part of this work aimed to compare two different reactor operation modes for the production of short-chain organic acids (SCOA), preferred substrates for polyhydroxyalkanoates (PHA) production. Acidogenic fermentation was performed by mixed microbial cultures (MMC) in a continuously stirred tank reactor (CSTR) and in a sequential batch reactor (SBR) operated for 130 days and submitted to the same operational conditions. Both reactors achieved full fermentation (>90%) for an OLR of 10gCOD/L·d, with a different range and relative concentrations of fermentation products (FP). Ethanol (EtOH) was the dominant FP in the CSTR and acetic acid (HAc) the main SCOA produced, while the SBR presented butyric acid (HBu) as dominant FP, slightly higher than the HAc concentration. Although the CSTR showed a higher yield of SCOA than the SBR – 0.671 and 0.604, respectively -, the SBR presented a higher conversion of substrate into SCOA – 48% over 38%. The second part of the work focused on the PHA extraction from pure cultures of C. necator and MMC with surfactants and an enzymatic solution from the hydrolysate of the fungus P. variotii. An extraction protocol was developed for application of the extractive agents studied. Afterwards, a systematic extraction of PHA from the microbial cultures was performed and several concentrations and temperatures tested. Among the surfactants used, BRIJ 30 presented the most promising results with recoveries above 30% for the pure cultures and above 20% for the MMC. The enzymatic solution enabled the PHA extraction when used at a concentration of 10% but not in inferior percentages, indicating that application of higher concentrations should be studied.
Os polihidroxialcanoatos (PHA) apresentam-se como uma alternativa promissora aos plásticos convencionais, devido à sua biodegradabilidade, biocompatibilidade e propriedades termoquímicas. Várias estratégias têm sido estudadas para reduzir os custos de produção de PHA e ampliar a sua comercialização, como o uso substratos renováveis sujeitos a um pré-tratamento e o desenvolvimento de procedimentos de extração económica e ambientalmente sustentáveis. A primeira parte do trabalho consistiu na comparação de dois modos de operação de reator distintos para a produção de ácidos orgânicos de cadeia curta (AOCC), substratos preferidos para a produção de PHA. A fermentação acidogénica foi protagonizada por culturas microbianas mistas (CMM), num reator contínuo perfeitamente agitado (CSTR) e num reator descontínuo sequencial (SBR), operados durante 130 dias sob as mesmas condições operacionais. Ambos os reatores atingiram fermentação total (>90%) para a carga orgânica de 10gCOD/L·d, com gama de produtos de fermentação (PF) e respetivas concentrações relativas distintas. Etanol foi o PF dominante no CSTR e ácido acético (HAc) o principal AOCC produzido, enquanto o SBR apresentou dominância pelo ácido butírico (HBu), com concentração pouco acima do HAc. Apesar do CSTR ter tido maior rendimento de AOCC que o SBR - 0.671 e 0.604, respetivamente - o SBR teve uma conversão de substrato em AOCC superior – 48% comparativamente a 38%. A segunda parte do trabalho incidiu na extração de PHA de culturas puras de C. necator e CMM com aplicação de surfatantes e solução enzimática de hidrolisado do fungo P. variotii. Inicialmente, foi desenvolvido um protocolo para aplicação dos agentes extrativos em estudo. Após, foi feita a extração sistemática de PHA das culturas microbianas seguindo o protocolo desenvolvido e combinando valores de temperatura e concentração. Dos surfatantes utilizados, o BRIJ 30 apresentou resultados mais promissores com recuperações de polímero acima de 30% para as culturas puras e acima de 20% para as CMM. A solução enzimática permitiu extração de PHA em concentração de 10% mas não em concentrações inferiores, indicando que concentrações mais elevadas deverão ser estudadas.

Increased possibilities during the last decades for early detection of prostate cancer have sparked research on preventable or treatable risk factors and on improvements in therapy. Treatments of the disease still entail significant side effects potentially affecting men during the rest of their lives. The studies of the present thesis concern different aspects of prostate cancer from etiological risk factors and factors influencing treatment to an improved methodology for the detection of treatment side effects. Papers I, II, both based in the population based cohort ULSAM (Uppsala Longitudinal Study of Adult Men), investigate possible risk factors of prostate cancer with options for intervention: selenium levels and the metabolic syndrome. The phenomenon of competing risk of death from other causes than prostate cancer and its impact on and importance for choice of statistical methods is also exemplified and discussed for the first time in prostate cancer research. -Smokers with low selenium status have an increased future risk of later development of prostate cancer. Influence of genetic variability appears plausible. -The metabolic syndrome and especially its increased waist circumference component are associated with later development of prostate cancer – taking competing risks of death from other causes into account. Papers III and IV using pharmacoepidemiological methods investigate aspects of drug utilisation in prostate cancer using nationwide and international databases. In Paper III factors influencing anti-androgen use in prostate cancer are investigated, both from a prescriber- and patient perspective.  The age and disease risk group of the patient, unsupported scientifically, influence both the prescribers’ choice of dose and the patients’ adherence to treatment. -Adherence, not previously investigated in male cancer patients, was considerably higher than reported for adjuvant breast cancer treatment. Subgroups of men suitable for intervention to increase adherence were identified. Paper IV, investigates the feasibility of improving an established method for screening large adverse drug reactions databases, the proportional reporting ratio (PRR), this by using restricted sub-databases according to treatment area (TA), introducing the concept of PRR-TA. -The PRR-TA method increases the signal-noise relationship of analyses; a finding highly relevant for possibly conserving manual resources in Pharmacovigilance work in a drug-authority setting.

Dans le cadre du projet ASTRID ((Advanced Sodium Technological Reactor for Industrial Demonstration), les interactions fluide-structure mettant en jeu la dynamique du coeur (gerbage), tels qu'elles peuvent survenir lors d'un séisme, sont d'un grand intérêt. Le gerbage du coeur est également reconnu comme l'événement le plus plausible pour expliquer les quatre AURN (Arrêt d'Urgence pour Radioactivité Négative) survenus dans le réacteur Phénix, durant les années 1989 et 1990. L'objectif poursuivi est d'améliorer, pour leurs aspects dynamiques, la compréhension des interactions fluide-structure susceptibles de se produire dans un SFR (Sodium Fast Reactor). Le centre d'intérêt principal étant phénomène de dissipation visqueuse, cette thèse entreprend trois approches expérimentales, numérique et analytique, en s'appuyant sur des expériences de vibrations libres menées sur deux installations, PISE1A, mono-assemblage et PISE2C, multi-assemblages. Deux séries d'expériences de vibrations libres ont été menées sur PISE1A, en faisant varier la hauteur d'eau et en utilisant un mélange d'eau et de glycérol, dans des proportions variables. Le but est d'examiner l'influence des variations de masse ajoutée et de viscosité sur la dynamique des oscillations de l'assemblage. Les simulations numériques correspondantes, développées dans le code CAST3M, se sont appuyées sur la résolution des équations de Navier-Stokes 3D. Les écarts entre les résultats numériques et expérimentaux sont présentés et analysés. En particulier, les effets d'extrémité se sont révélés être d'une importance marginale. Des expériences de vibrations libres ont également été effectuées sur PISE2C en sollicitant l'installation de trois façons différentes : mise en mouvement globale, mise en mouvement par la couronne externe puis par la couronne interne. Un modèle réticulé, fondé sur des hypothèses de symétrie et de linéarité a été développé parallèlement. Les résultats expérimentaux ont permis de confirmer les symétries mais ont remis en cause les hypothèses de linéarité. Ce résultat encourage à persévérer dans la voie des modèles déterministes
In the scheme of French ASTRID (Advanced Sodium Technological Reactor for Industrial Demonstration) project, fluid-structure interaction phenomena involved in the dynamic behaviour of core flowering, which could happen during seismic events, are of high interest. Also core flowering behaviour is considered as the main initiating event for the four SCRAMs that happened in Phénix reactor during 1989 and 1990. In objective to improve the knowledge of fluid-structure interaction phenomena of dynamic issues in a SFR core, especially focused on damping, this Ph.D. thesis have been conducted in experimental, numerical and analytical approaches based on free-vibration experiments on mono-assembly test facility PISE-1A and multi-assembly test facility PISE-2C. Two series of free-vibration experiments have been performed on PISE-1A with different water heights and different mass fractions of water-glycerol mixtures to examine the dynamic behaviours with respect to different added mass, different densities and viscosities. Corresponding numerical interpretations have been conducted with 3D Navier-Stokes model in CAST3M code. Sources of uncertainties are discussed to explain the discrepancies between the numerical computation and experimental results. Edge effects are not found to have an important impact on the dynamic behaviours of the system. On PISE-2C, free-vibration experiments with different modes of excitations have been conducted, including total flowering, partial flowering with internal crown excited and partial flowering with external crown excited. A reticulate model with homogenised linear hypothesis has been developed to interpret PISE-2C experiments. Good symmetries are found in PISE-2C suggesting that the deterministic tool is valid for the analysis

A presente pesquisa propôs avaliar a remoção biológica do nitrogênio pela via simplificada (nitritação) utilizando fenol como fonte de carbono na etapa anóxica (desnitritação) em um sistema de lodos ativados com biomassa em suspensão. Para tanto operou-se um reator piloto (volume útil de 20 litros) em bateladas seqüenciais alimentado com 5 (cinco) litros de água residuária sintética. A investigação foi caracterizada pela utilização do fenol (1.000 mg C6H5OH/L) e pelo aumento gradual da concentração de nitrogênio amoniacal no despejo líquido sintético (200; 300 e 500 mg N/L) buscando as condições que permitissem a predominância do N-NO2 - ao final da fase aeróbia dos ciclos de tratamento e utilização do fenol pelos microrganismos heterotróficos para redução do nitrogênio oxidado durante a fase anóxica. Para a presente pesquisa as condições para predominância do N-NO2 - na massa líquida do reator ao final da etapa aeróbia foram: pH @ 8,3 associado à extensão do período aeróbio do ciclo de tratamento que garantisse uma concentração mínima de amônia livre (> 0,3 mg NH3/L) no conteúdo do reator piloto. Com estas condições, a relação N NO2 - / (N-NO2 - + N-NO3 -) variou entre 89 e 99%. Mantendo uma concentração de 1,0 mg O2/L no conteúdo do reator durante afase aeróbia e tempo de residência hidráulico de três dias, as eficiências de remoção de N-NH3 variaram entre: 89 e 98% com concentrações no afluente próximas a 200 mg N/L (nove ciclos de tratamento); 95 e 98% para concentrações no afluente da ordem de 300 mg N/L (cinco ciclos de remoção) e 95 e 97% com concentrações no afluente próximas a 500 mg N/L (três ciclos de tratamento). Para temperaturas entre 23,5 e 33°C e concentrações de sólidos em suspensão voláteis entre 3.420 e 2.175 mg SSV/L no conteúdo do reator, a taxa de nitrificação específica variou entre 0,01 e 0,05 kg N-NH3/ kg SSV. dia. Concentrações máximas de amônia livre da ordem de 16 mg NH3/L e de ácido nitroso livre entre 0,001 e 0,009 mg HNO2/L no conteúdo do reator piloto não inibiram a oxidação biológica do nitrogênio. Fenol, em concentrações no afluente próximas a 1.000 mg C6H5OH/L, mostrou-se adequado como única fonte de carbono para remoção de nitrogênio, via nitrito, para concentrações afluentes da ordem de 200 e 300 mg N/L. As eficiências de remoção do nitrogênio oxidado variaram entre 97 e 100%, utilizando taxas de aplicação volumétricas próximas a 0,03 kg fenol /m3.hora.. As taxas de "desnitritação" específicas variaram entre 0,01 e 0,05 kg N-NO2 - / kg SSV .dia; a relação alimento/microrganismo (A/M) esteve compreendida entre 0,06 e 0,13 kg fenol / kg SSV. dia; a relação fenol removido/N-NOx removido variou entre 2,1 e 3,2 g fenol removido / g NNOx removido e as eficiências de remoção do fenol, durante a etapa anóxica estiveram compreendidas entre 37 e 67%. Taxas de aplicação volumétricas da ordem de 0,07 kg fenol /m3.hora inibiram a "desnitritação" biológica. Os três ciclos de tratamento da etapa conduzida com concentração de 500 mg N/L no afluente, foram marcados pela inibição da "desnitritação" e acúmulo de fenol, causados pelas elevadas concentrações de N-NO2 - (@80 a 98 mg N-NO2 -/L) na massa líquida do reator. Ainda durante essa etapa, a coleta de amostra na fase anóxica dos ciclos de remoção para realização de ensaios exploratórios, associando cromatografia gasosa e espectrometria de massa, detectaram a formação de 2 e 4 - nitrofenol no conteúdo do reator piloto.
This research proposes to evaluate an activated sludge system with suspended biomass in a pilot scale aiming to remove nitrogen by a simplified way (nitritation) using phenol as the carbon source of the anoxic phase (denitritation). A pilot reactor of 20-liters volume was operated in sequence batch stages fed with 5-liters of a synthetic wastewater. The investigation was characterized by the use of phenol (1,000 mg C6H5OH/L) and the gradual increase of ammonium nitrogen concentration in the synthetic wastewater (200, 300 and 500 mg N/L) searching the conditions that allowed the prevalence of N-NO2 - in the end of the aerobic phase of the treatment cycles and the use of phenol for the heterotrophic microorganisms to reduce the oxidized nitrogen during the anoxic phase. To the present research, the conditions to N-NO2 - prevalence in the reactor liquid mass in the end of the aerobic phase were: pH @ 8.3 associated to the extension of the aerobic period of the treatment cycle which guarantees a minimum concentration of free ammonia (> 0.3 mg NH3/L) in the pilot reactor content. Considering these conditions, the relation N-NO2 - / (N-NO2 - + NNO3 -) varied between 91 and 99%. Maintaining a concentration of 1.0 mgO2/L in the reactor content and hydraulic residence time of three days, the removal efficiencies of N-NH3 vary between: 89 and 98% to influent concentrations near 200 mg N/L (nine treatment cycles); 95 and 98% to influent concentrations of the order of 300 mg N/L (five removal cycles) and 95 and 97% to influent concentrations near 500 mg N/L (three treatment cycles). To temperature between 23,5 and 33°C and volatile suspended solid concentrations between 3,420 and 2,175 mg SSV/L in the reactor, the specific nitrification rate varied between 0.01 and 0.05 kg N-NH3/ kg SSV.d-1. Maximum concentrations of free ammonia in the pilot reactor of the order of 16 mg NH3/L and nitrous acid between 0.001 and 0.009 mg HNO2/L didn?t inhibit the nitrogen biological oxidation. Influent phenol concentrations near 1,000 mg C6H5OH/L showed to be adequate as single carbonsource to nitrogen removal as nitrite to influent concentrations of the order of 200 and 300 mg N/L. The oxidized nitrogen removal efficiencies vary between 97 and 100%, using volumetric loading rates near 0.03 kg phenol/m3.hour. The specific denitritation rates vary between 0.01 and 0.05 kg N-NO2 - / kg SSV.d-1; the food / microorganism ratio (F/M) was between 0.06 and 0.13 kg phenol / kgSSV.d-1; phenolremoved/N-NOxremoved ratio varied between 2.1 and 3.2 g phenolremoved/ g N-NOxremoved and phenol removal efficiencies during the anoxic phase were between 37 and 67%. Volumetric loading rates of the order of 0.06 kg phenol / m3.hour inhibited the biological denitritation. The three treatment cycles of the phase conducted with influent concentration of 500 mg N/L showed denitritation inhibition and phenol accumulation caused by high concentrations of N-NO2 - (@80 to 98 mg N-NO2 -/L) in the reactor liquid mass. During this phase, the sampling of the anoxic phase of the removal cycles to the initial tests associating gas chromatography and mass spectrophotometer detected the formation of 2 and 4-nitrophenol in the pilot reactor content.

Thesis advisor: J. Scott Miller
The development of two catalytic asymmetric synthetic methods is presented and culminates with studies of their application to the synthesis of a natural product. The intramolecular variant of the Morita-Baylis-Hillman (MBH) reaction has remained almost untouched by asymmetric catalysis. A significant advance in the field is demonstrated with the development of a highly enantioselective intramolecular MBH reaction employing a co-catalytic system of N-methylimidazole (NMI) and pipecolinic acid (Pip). The optimization of various reaction parameters and the use of protic conditions (THF-H2O, 3:1) afforded the desired products in up to 82% yield and 80% ee. The extension of this methodology to include the use of vinylogous reaction partners in the Rauhut-Currier (RC) reaction has been achieved, establishing the first highly enantioselective RC reaction. A single amino acid derivative of cysteine, in the presence of potassium tert-butoxide and a critical concentration of water in acetonitrile, was demonstrated to function as a highly selective catalyst providing products in up to 95% ee. Finally, the application of the MBH and RC reactions to the synthesis of complex molecules presents highly useful methodology for the formation of a new C–C bond in the generation of densely functionalized enantiopure products. Preliminary studies toward the application of this methodology to the stereoselective synthesis of (+)-Sch 642305 are described. Examination of the catalyst’s ability to dictate the stereoselectivity of the key step (catalyst control) and allow the synthesis of both the natural product, and difficult-to-obtain unnatural stereoisomeric analogs, will be the subject of on-going studies
Thesis (PhD) — Boston College, 2008
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Chemistry

In computing the available computing power has continuously fallen short of the demanded computing performance. As a consequence, performance improvement has been the main focus of processor design. However, due to the phenomenon called 'Power Wall' it has become infeasible to build faster processors by just increasing the processor's clock speed. One of the resulting trends in hardware design is to integrate several simple and power-efficient cores on the same chip. This design shift poses challenges of its own. In the past, with increasing clock frequency the programs became automatically faster as well without modifications. This is no longer true with many-core architectures. To achieve maximum performance the programs have to run concurrently on more than one core, which forces the general computing paradigm to become increasingly parallel to leverage maximum processing power. In this thesis, we will focus on the Reactive Stream Program (RSP). In stream processing, the system consists of computing nodes, which are connected via communication streams. These streams simplify the concurrency management on modern many-core architectures due to their implicit synchronisation. RSP is a stream processing system that implements the reactive system. The RSPs work in tandem with their environment and the load imposed by the environment may vary over time. This provides a unique opportunity to increase performance per watt. In this thesis the research contribution focuses on the design of the execution layer to run RSPs on tiled many-core architectures, using the Intel's Single-chip Cloud Computer (SCC) processor as a concrete experimentation platform. Further, we have developed a Dynamic Voltage and Frequency Scaling (DVFS) technique for RSP deployed on many-core architectures. In contrast to many other approaches, our DVFS technique does not require the capability of controlling the power settings of individual computing elements, thus making it applicable for modern many-core architectures, with which power can be changed only for power islands. The experimental results confirm that the proposed DVFS technique can effectively improve the energy efficiency, i.e. increase the performance per watt, for RSPs.

One of the proposed solutions to the issue of nuclear waste volume is to transition from once through nuclear fuel cycle to advanced fuel cycles with used fuel recycling option. In any advanced fuel cycles with recycling options, the type and amount of separation technology deployed play a crucial role in the overall performance of the fuel cycle. In this work, a scenario study involving two advanced fuel cycles in addition to the once through fuel cycle were evaluated using VISION nuclear fuel cycle simulation code. The advanced fuel cycles were setup to transition completely to full recycling without any light water reactor by assuming all LWR currently in operation will have 20 years of operating life extension and no new LWR will be constructed thereafter. Several different separation capacities (1kT/yr, 2kT/yr and 4 kT/yr) were deployed and the overall impact of these capacities was analyzed in terms of resources utilization, used fuel and waste material generated and the amount of storage space required. Economic parameter (LCOE, LFCC, etc) analysis was also performed using VISION.ECON. Results presented in this work suggest that the need for LWR-UNF storage can be minimized if sufficient separation capacity is deployed early in the fuel cycle. It can also be concluded that a FuRe system without LEU will not be feasible, thus SFRs must be designed for optional use of LEU fuel. Otherwise LWRs must continue to be part of the mix to keep the near term cost of generating electricity competitive. It was observed that the higher amount of separation capacity deployed in the advanced fuel cycles led to higher LFCC and LCOE, but also translates into less environmental impact on both front and back end of the fuel cycle.