Microalloyed steels are widely used in oil and gas pipelines. They are a class of high strength, low carbon steels containing small additions (in amounts less than 0.1 wt%) of Nb, Ti and/or V. The steels may contain other alloying elements, such as Mo, in amounts exceeding 0.1wt%. Microalloyed steels have good strength, good toughness and excellent weldability, which are attributed in part to the presence of precipitates, especially nano-precipitates with sizes less than 10nm. Nano-precipitates have an important strengthening contribution, i.e. precipitation strengthening. In order to fully understand steel strengthening mechanisms, it is necessary to determine the precipitation strengthening contribution. Because of the fine sizes and low volume fraction, conventional microscopic methods are not satisfactory for quantifying the nano-precipitates. Matrix dissolution is a promising alternative to extract the precipitates for quantification. Relatively large volumes of material can be analyzed, so that statistically significant quantities of precipitates of different sizes are collected. In this thesis, the microstructure features of a series of microalloyed steels are characterized using optical microscopy (OM) and scanning electron microscopy (SEM). Matrix dissolution techniques have been developed to extract the precipitates from the above microalloyed steels. Transmission electron microscopy (TEM) and x-ray diffraction (XRD) are combined to analyze the chemical speciation of these precipitates. Rietveld refinement of the XRD pattern is used to fully quantify the relative amounts of the precipitates. The size distribution of the nano-precipitates (mostly 10 nm) is quantified using dark field imaging (DF) in the TEM. The effects of steel chemistry and processing parameters on grain microstructure and the amount of nano-precipitates are discussed. Individual strengthening contributions due to grain size effect, solid solution strengthening and precipitation strengthening are quantified to fully understand the strengthening mechanisms of the steels. / Materials Engineering

Coal fly ash is a by-product of coal combustion that has drawn renewed public scrutiny due to the negative environmental impacts from accidental release of this waste material from storage facilities. Historically, the leaching of toxic elements from coal fly ash into the environment has always been a major environmental concern. Despite extensive efforts into the characterization of coal fly ash, effective models for the fate and transport of toxic fly ash constituents have remained lacking, making it difficult to perform accurate environmental impact assessment for coal fly ash. To close this critical knowledge gap, the overall objective of this study was to develop a predictive model for the leaching of toxic elements from fly ash particles. First, physical properties of coal fly ash were characterized to evaluate their contribution to elemental transport. Unburned carbon was shown to contribute to the sorption of arsenic to fly ash, which slowed the release of arsenic from fly ash. In parallel, leaching properties of various elements were determined to differentiate species of varying leaching capacities, demonstrating that the majority of toxic elements were not mobile under environmentally relevant conditions. Subsequently, a mechanistic model for the dissolution of fly ash elements was developed and validated with batch kinetics studies. Furthermore, elemental dissolution was integrated with hydrodynamic modeling to describe the leaching of toxic elements from fly ash in dry disposal facilities, which was validated by column studies. The mechanistic model developed and validated in this research represents the first such model that successfully characterized the complex processes underlying the release and transport of toxic elements in coal fly ash, providing a valuable tool to predict the environment impact of coal fly ash and develop more effective management practices for both the industry and regulators.

In Sweden, among other countries, a deep multi-barrier geological repository, KBS-3, is planned for the burial of nuclear waste. One of the barriers is identified as the grantic bedrock itself and in this environment chlorite is present at surfaces in fracture zones. This thesis is focused on characterisation of chlorite samples and studies of their dissolution and sorption behaviour, in order to verify chlorites capacity to retard possible radionuclide migration in the case of leaking canisters. Chlorite dissolution of has been studied in the pH interval 2-12, and as expected the dissolution is highest at acidic pH and at most alkaline pH, whereas dissolution is lowest at near neutral pH values. Chemical and physical properties of chlorites clearly influence the dissolution rates, and at steady-state dissolution rates in the interval 10-12 ‑ 10-13 mol g-1 s-1 was observed. Sorption studies were performed since Ni(II) is one of the important activation products in spent nuclear fuel and sorption data on minerals like chlorite are lacking. Ni(II) sorption onto chlorite was studied using batch technique as a function of; pH, concentration of Ni(II), ionic strength and solid concentrations. As expected, the sorption of Ni(II) onto chlorite was pH dependent, but not ionic strength dependent, with a sorption maximum at pH ~ 8, and with a Kd of ~ 103 cm3/g. This confirms that the Ni(II) sorption onto chlorite is primarily acting through surface complexation. The acid-base properties were determined by titrations and described by a non-electrostatical surface complexation model in FITEQL. Further, the sorption results were fit with a 2-pK NEM model and three surface complexes, Chl_OHNi2+, Chl_OHNi(OH)+ and Chl_OHNi(OH)2, gave the best fit using FITEQL. / Sverige är ett av de länder som planerar ett geologiskt slutförvar kallad KBS-3, bestående av ett antal barriärer, för placering utav det använda kärnbränslet. En av dessa barriärer är identifierad som själva berggrunden där det tilltänkta förvaret kommer att byggas och i denna miljö förekommer klorit på granitytor i sprickzoner. Denna doktorsavhandling karakteriserar kloriter och studerar deras upplösnings- och sorptionsbeetende, för att kunna bestämma huruvida kloriter är utav betydelse som naturlig barriär för eventuell radionuklidtransport från det använda kärnbränslet. Upplösning av klorit har undersökts i pH intervallet 2-12 och graden av upplösningen är som förväntat högst vid sura respektive mest basiska pH och lägst där pH är neutralt. Denna studie bekräftar att den kemiska sammansättning och de fysikaliska egenskaper hos kloriterna påverkar upplösningshastigheterna och vid steady‑state har upplösningshastighet bestämts till 10-12 ‑ 10-13 mol g-1 s-1. Sorptionsstudier genomfördes då Ni(II) är en viktig aktiveringsprodukt och data rörande Ni(II) sorption till klorit saknas. Ni(II) sorption till klorit har studerats i; varierande pH, olika initiala Ni(II) koncentrationen, olika jonstyrka och olika fastfas förhållanden där individuella satser i serie har nyttjats. Som förväntat är sorptionen av Ni(II) till klorit pH beroende men inte jonstyrkeberoende och ett sorpions maximum observerades vid pH ~ 8, med ett Kd‑värde på ~ 103 cm3/g. Från detta dras slutsatsen att sorptionen av Ni(II) till klorit sker mestadels genom ytkomplexering. Syra-bas egenskaperna hos kloriterna bestämdes genom titreringar och bekrevs med en icke‑elektrostatisk modell i FITEQL. Vidare har passning av sorptionsresultaten utförts med en 2-pK NEM-modell och tre ytkomplex, Chl_OHNi2+, Chl_OHNi(OH)+ och Chl_OHNi(OH)2, vilket gav den bästa passningen av data med FITEQL. / QC 20100819

Many banks provide very similar services and that is why creating and maintaining relationships to clients is a differentiation strategy to get customer to return. Private advising is one service provided by banks where much interaction occurs and relationship is of great importance. The relationship between private advisers and their clients is therefore suitable for research. Knowing why a relationship ends is a strategic piece of information to improve the firm’s ability to keep customers in a relationship. The purpose of this paper is to identify the issues that lead to dissolution of a relationship and where they occur in the relationship development process between private advisors and clients. A pre-study was first made on Swedbank, through interviews, to obtain a holistic view of the situation. More in-depth interviews followed as well as triangulation through a questionnaire. The thesis presents seven issues that can lead to dissolution of the relationship: better offering from competitors, availability, personal factors, unachievable demands, no need for service, lack of certain services, and requirement not fulfilled. These issues have also been related to where in the relationship development process they occur and ranked in order to know how common it is for them to occur. / De flesta banker erbjuder sina kunder väldigt snarlika tjänster och därför har skapandet av relationer blivit en differentierings strategi för att få kunder att komma tillbaka. Privatrådgivning är en tjänst som banker erbjuder där mycket interaktion sker och relationer är oerhört viktiga. På grund av detta så är relationen mellan privatrådgivaren och dess klient passande att undersöka Att veta varför en relation avslutas är väldigt viktig strategisk information som kan användas för att förbättra en firmas möjlighet att bevara kunder. Syftet med den här uppsatsen är att identifiera de problem som kan leda till att en relation bryts och även att identifiera vart i relationsbyggnads processen dessa problem uppstår. En förstudie genomfördes först för att få en överblickande bild över ämnet. Efter denna så följde även mer djupgående intervjuer samt metodtriangulering med hjälp av ett frågeformulär som skickades ut till Swedbanks privatrådgivare. Uppsatsen presenterar sju problem som kan leda till upplösningen av en relation: bättre erbjudanden från konkurrenter, tillgänglighet, personliga faktorer, ouppnåeliga krav, inget behov av tjänst, brist på en viss tjänst samt att kunden inte uppfyller krav. Dessa problem har även relaterats till vart I relationsbyggnads processen de uppstår och rankats i ordning beroende på hur vanligt de är att problemen uppstår.

<p>This thesis presents an analysis of the material properties and phase behavior of divalent ionic surfactant salts, and protein and polymer glasses. There has been extensive interest in understanding the phase behavior of divalent ionic surfactants due to the many applications of ionic surfactants in which they come into contact with divalent ions, such as detergency, oil recovery, and surfactant separation processes. One goal of determining the phase boundaries was to explore the option of incorporating a hydrophobic molecule into the solid phase through the micelle-to-crystal bilayer transition, either for drug delivery applications (with a biologically compatible surfactant) or for the purpose of studying the hydrophobic molecule itself. The liquid micellar and solid crystal phases of the alkaline earth metal dodecyl sulfates were investigated using calorimetry, visual inspection, solubilization of a fluorescent probe, and x-ray diffraction. The Krafft temperature and dissolution enthalpy were determined for each surfactant, and partial composition-temperature phase diagrams of magnesium dodecyl sulfate-water, calcium dodecyl sulfate-water, as well as sodium dodecyl sulfate with MgCl₂ and CaCl₂ are presented. As a proof of concept, fluorescence microscopy images showed that it is, in fact, possible to incorporate a small hydrophobic molecule, diphenylhexatriene, into the solid phase.</p><p>The second, and main, part of this thesis expands on work done previously in the lab by using the micropipette technique to study two-phase microsystems. These microsystems consist of a liquid droplet suspended in a second, immiscible liquid medium, and can serve as direct single-particle studies of drug delivery systems that are formed using solvent extraction (e.g., protein encapsulated in a biodegradable polymer), and as model systems with which to study the materials and principles that govern particle formation. The assumptions of the Epstein-Plesset model, which predicts the rate of droplet dissolution, are examined in the context of the micropipette technique. A modification to the model is presented that accounts for the effect a solute has on the dissolution rate. The modification is based on the assumption that the droplet interface is in local thermodynamic equilibrium, and that the water activity in a solution droplet can be used to determine its dissolution (or dehydration) rate. The model successfully predicts the dissolution rates of NaCl solutions into octanol and butyl acetate up to the point of NaCl crystallization. The dehydration of protein solutions (lysozyme or bovine serum albumin) results in glassified microbeads with less than a monolayer of water coverage per protein molecule, which can be controlled by the water activity of the surrounding organic medium. The kinetics of dehydration match the prediction of the activity-based model, and it is shown how the micropipette technique can be used to study the effect of dissolution rate on final particle morphology. By using a stable protein with a simple geometry (lyosyzme), this technique was be used to determine the distance dependence of protein-protein interactions in the range of 2-25 &Aring;, providing the first calculation of the hydration pressure decay length for globular proteins. The distance-dependence of the interaction potential at distances less than 9 &Aring; was found to have a decay length of 1.7 &Aring;, which is consistent with the known decay length of hydration pressure between other biological materials. Biodegradable polyesters, such as poly(lactide-co-glycolide) (PLGA), are some of the most common materials used for the encapsulation of therapeutics in microspheres for long-term drug release. Since they degrade by hydrolysis, release rates depend on water uptake, which can be affected by processing parameters and the material properties of the encapsulated drug. The micropipette technique allows observations not possible on any bulk preparation method. Single-particle observations of microsphere formation (organic solvent extraction into a surrounding aqueous phase) show that as solvent leaves the microsphere and the water concentration in the polymer matrix becomes supersaturated, water phase separates and inclusions initially grow quickly. Once the concentration in the polymer matrix equilibrates with the surrounding aqueous medium, the water inclusions continue to grow due to dissolved impurities, solvent, and/or water-soluble polymer fragments resulting from hydrolysis, all of which locally lower the water activity in the inclusion. Experiments are also presented in which glassified protein microbeads were suspended in PLGA solution prior to forming the single microspheres. This technique allowed the concentration of protein in a single microbead/inclusion to be determined as a function of time.</p> / Dissertation

<p>This thesis addresses mass transfer in multi-phase single particle systems. By using a novel technique based upon the micropipette, the dissolution of liquid and gas droplets in a liquid medium can be observed. Three classes of experimental systems are observed: pure liquid droplet dissolution in a pure liquid environment, miscible mixture liquid droplet dissolution in a pure liquid environment, and solute-containing liquid droplet dissolution in a pure liquid environment. Experiments on the dissolution of pure droplets of water in n-alcohols and n-alkanes showed that water droplets dissolved ten times faster in the alcohols as compared to in the alkanes. When solubility was taken into account, however, and diffusion coefficients calculated using the Epstein-Plesset equation, diffusion constants for alkanes were twenty five times higher in alkanes than for the corresponding alcohol (for example 12.5 vs 0.5 x 10-8 cm2/s for pentane and pentanol). This difference in rates of diffusion of the single molecules reflects the effect of hydrogen bonding on small solute diffusion, which is expounded upon in Chapter 2.</p><p> A model for the dissolution of a droplet containing a mixture, each component of which is soluble in the surrounding liquid medium is presented in Chapter 3. The model is based upon a reduced surface area approximation and the assumption of ideal homogenous mixing : Mass flux (dm_i)/dt=&#12310;Afrac&#12311;_i D_i (c_i-c_s){1/R+1/&#8730;(&#960;D_i t)}, where Afraci is the area fraction of component i, ci and cs are the initial and saturation concentrations of the droplet material in the surrounding medium, respectively, R is the radius of the droplet, t is time, and Di is the coefficient of diffusion of component i in the surrounding medium. This model was tested for the dissolution of ethyl acetate and butyl acetate in water and the dissolution of butyl acetate and amyl acetate in water, and was found to provide a good fit. In Chapter 4, a partial differential equation, R^2/D &#9500; &#8706;c/&#8706;t&#9508;|_&#951;=(&#8733;&#951;)/D &#8706;c/&#8706;&#951;+(&#8706;^2 c)/&#12310;&#8706;&#951;&#12311;^2 +2/&#951; &#8706;c/&#8706;&#951;, is presented for the dissolution of a solute containing droplet in a liquid medium, and shell or bead formation is predicted. In Chapter 5, an application of the solute containing droplet dissolution is presented in which suspensions of glassified protein microspehres are used to improve the injectability of protein based pharmaceuticals. Injectability is related to viscosity, and the viscosity of a suspension may be predicted to follow the Krieger Dougherty equation: (&#951;(&#934;))/&#951;_0 =(1-&#934;/&#934;_m )^(-2.5&#934;_m ) , where &#934; is the volume fraction of the suspensate, &#951; is the viscosity of the overall suspension, &#951;0 is the viscosity of the suspending fluid, and &#934;m is the maximum possible volume fraction. Finally, in Chapter 6, various experimental methods used to generate droplets are addressed.</p> / Dissertation

The behaviour of hydrocarbon fuels in contaminated groundwater systems is studied using a multicomponent reactive transport model. The simulated processes include residual NAPL dissolution, aerobic and anaerobic biodegradation with daughter-product transport, and transport of a reactive carrier with mixed equilibrium/kinetic sorption. The solution algorithm is based on a three-dimensional Galerkin finite element scheme with deformable brick elements and capacity for a free watertable search. Nonlinearities are handled through Picard iteration. Convergence is rapid for most applications and mass balance errors for all phases are minimal. The model is first applied to simulate a pilot scale diesel fuel dissolution experiment in which humic acid is used as a natural organic carrier to enhance dissolution and to promote biodegradation of the aqueous components. The pilot scale experiment is described by Lesage et al. (1995) and Van Stempvoort et al. (2000). The conceptual model includes 8 unique components dissolving from 500 mL of residual diesel fuel within a 3D saturated domain. Oxygen-limiting competitive aerobic biodegradation with a dynamic microbial population is also included. A mixed 2-site equilibrium/kinetic model for describing sorption of the carrier to the aquifer solids was adopted to reproduce the observed breakthrough of the humic acid and organic components. Most model parameters were obtained independently with minimal calibration. Batch sorption data were found to fit well at the pilot scale, however biodegradation and dissolution rates were not well known and had to be fitted. Simulations confirmed the observed 10-fold increase in effective solubility of trimethylnaphthalene, and increases on the order of 2-5 for methyl- and dimethylnaphthalene. The simulated plumes showed almost complete attenuation after 5 years, in excellent agreement with observed data. A sensitivity analysis showed the importance of carrier concentrations, binding coefficients, dissolution and biodegradation rates. Compared to a dissolution scenario assuming no carrier, the humic acid-enhanced dissolution case decreased the remediation time by a factor of about 5. The second application of the model involves simulating the effect of ethanol on the persistence of benzene in gasoline-impacted groundwater systems. The conceptual model includes a 4-component residual gasoline source which is dissolving at the watertable into a 3D aquifer. Comparisons are made between dissolved plumes from a gasoline spill and those from an otherwise equivalent gasohol spill. Simulations have shown that under some conditions, a 10% ethanol component in gasoline can extend the travel distance of a benzene plume by at least 150% relative to that from an equivalent ethanol-free gasoline spill. The increase is due to preferred consumption of oxygen by ethanol and a corresponding reduction in the biodegradation rate of benzene while the two plumes overlap. Because of differences in retardation however, the ethanol and benzene plumes gradually separate. The impact therefore becomes limited because oxygen rapidly disperses behind the ethanol plume and benzene degradation eventually resumes. A sensitivity analysis for two common spill scenarios showed that background oxygen concentrations, and benzene retardation had the most significant influence on benzene persistence. A continuous gasohol spill over 10 years was found to increase the benzene travel distance by over 120% and a pure ethanol spill into an existing gasoline plume increased benzene travel distance by 150% after 40 years. The results are highly relevant in light of the forthcoming ban of MTBE in California and its likely replacement by ethanol by the end of 2002.

The behaviour of hydrocarbon fuels in contaminated groundwater systems is studied using a multicomponent reactive transport model. The simulated processes include residual NAPL dissolution, aerobic and anaerobic biodegradation with daughter-product transport, and transport of a reactive carrier with mixed equilibrium/kinetic sorption. The solution algorithm is based on a three-dimensional Galerkin finite element scheme with deformable brick elements and capacity for a free watertable search. Nonlinearities are handled through Picard iteration. Convergence is rapid for most applications and mass balance errors for all phases are minimal. The model is first applied to simulate a pilot scale diesel fuel dissolution experiment in which humic acid is used as a natural organic carrier to enhance dissolution and to promote biodegradation of the aqueous components. The pilot scale experiment is described by Lesage et al. (1995) and Van Stempvoort et al. (2000). The conceptual model includes 8 unique components dissolving from 500 mL of residual diesel fuel within a 3D saturated domain. Oxygen-limiting competitive aerobic biodegradation with a dynamic microbial population is also included. A mixed 2-site equilibrium/kinetic model for describing sorption of the carrier to the aquifer solids was adopted to reproduce the observed breakthrough of the humic acid and organic components. Most model parameters were obtained independently with minimal calibration. Batch sorption data were found to fit well at the pilot scale, however biodegradation and dissolution rates were not well known and had to be fitted. Simulations confirmed the observed 10-fold increase in effective solubility of trimethylnaphthalene, and increases on the order of 2-5 for methyl- and dimethylnaphthalene. The simulated plumes showed almost complete attenuation after 5 years, in excellent agreement with observed data. A sensitivity analysis showed the importance of carrier concentrations, binding coefficients, dissolution and biodegradation rates. Compared to a dissolution scenario assuming no carrier, the humic acid-enhanced dissolution case decreased the remediation time by a factor of about 5. The second application of the model involves simulating the effect of ethanol on the persistence of benzene in gasoline-impacted groundwater systems. The conceptual model includes a 4-component residual gasoline source which is dissolving at the watertable into a 3D aquifer. Comparisons are made between dissolved plumes from a gasoline spill and those from an otherwise equivalent gasohol spill. Simulations have shown that under some conditions, a 10% ethanol component in gasoline can extend the travel distance of a benzene plume by at least 150% relative to that from an equivalent ethanol-free gasoline spill. The increase is due to preferred consumption of oxygen by ethanol and a corresponding reduction in the biodegradation rate of benzene while the two plumes overlap. Because of differences in retardation however, the ethanol and benzene plumes gradually separate. The impact therefore becomes limited because oxygen rapidly disperses behind the ethanol plume and benzene degradation eventually resumes. A sensitivity analysis for two common spill scenarios showed that background oxygen concentrations, and benzene retardation had the most significant influence on benzene persistence. A continuous gasohol spill over 10 years was found to increase the benzene travel distance by over 120% and a pure ethanol spill into an existing gasoline plume increased benzene travel distance by 150% after 40 years. The results are highly relevant in light of the forthcoming ban of MTBE in California and its likely replacement by ethanol by the end of 2002.

The research addressed in this thesis is focused on the solubility and pseudo-polymorphic transition of L-serine in mixed water-methanol systems. Cooling re-crystallizations were carried out that varied both temperature and methanol concentration. Solubilities were measured with high-performance liquid chromatography. It is found that the solubility increased with increase in temperature and decreased drastically with methanol concentration. The effect of temperature at which there is a transition of L-serine crystals from the rod-shaped (anhydrous) form to hexagonal (monohydrate) form was confirmed and that transition temperatures decreased with methanol concentrations in a non-linear manner. The solubility data were correlated and plotted using the vant Hoff equation and the enthalpy and entropy of dissolution were determined. These values increased with increase in methanol concentration. The solid crystals were analyzed by optical microscopy and powder X-ray diffraction. The rod-shaped crystals were identified to be anhydrous L-serine, while the hexagonal crystals were L-serine monohydrate. Dehydration of the monohydrated crystals in their solid-state was examined and the onset of such phenomenon was known to start once the crystals were removed from the solutions.

Aluminum and its alloys are used in many aspects of modern life, from soda cans and household foil to the automobiles and aircraft in which we travel. Aluminum alloy systems are characterized by good workability that enables these alloys to be economically rolled, extruded, or forged into useful shapes. Mechanical properties such as strength are altered significantly with cold working, annealing, precipitation-hardening, and/or heat-treatments. Heat-treatable aluminum alloys contain one or more soluble constituents such as copper, lithium, magnesium, silicon and zinc that individually, or with other elements, can form phases that strengthen the alloy. Microstructure development is highly dependent on all of the processing steps the alloy experiences. Ultimately, the macroscopic properties of the alloy depend strongly on the microstructure. Therefore, a quantitative understanding of the microstructural changes that occur during thermal and mechanical processing is fundamental to predicting alloy properties. In particular, the microstructure becomes more homogeneous and secondary phases are dissolved during thermal treatments. Robust physical models for the kinetics of particle dissolution are necessary to predict the most efficient thermal treatment. A general dissolution model for multi-component alloys has been developed using the front-tracking method to study the dissolution of precipitates in an aluminum alloy matrix. This technique is applicable to any alloy system, provided thermodynamic and diffusion data are available. Treatment of the precipitate interface is explored using two techniques: the immersed-boundary method and a new technique, termed here the sharp-interface method. The sharp-interface technique is based on a variation of the ghost fluid method and eliminates the need for corrective source terms in the characteristic equations. In addition, the sharp-interface method is shown to predict the dissolution behavior of precipitates in aluminum alloys when compared with published experimental results. The influence of inter-particle spacing is examined and shown to have a significant effect on dissolution kinetics. Finally, the impact of multiple particles of various sizes interacting in an aluminum matrix is investigated. It is shown that smaller particles dissolve faster, as expected, but influence the dissolution of larger particles through soft-impingement, even after the smaller particles have disappeared.