A one dimensional mass transfer analysis was performed for convective transport as well as mass transport within a porous media. This analysis was based on the analogous average heat transfer within a duct. Equations were developed to calculate the concentration of gas species at the triple phase boundary sites present at the interface of a porous electrode and a nonporous electrolyte. The mass transport analyzed on the steam side electrode of a solid oxide electrolysis cell was performed for a ternary gas mixture. In this analysis two gas species were actively diffusing in the presence of a third inert carrier gas. Multicomponent diffusion coefficients were determined for each species in the steam side electrode mixture. The mass transport analysis performed on the air side electrode utilized a binary gas mixture, namely air. At less than one percent of the total mixture of air, the combined effects of Argon and Carbon Dioxide were assumed to be negligible. This assumption allowed us to consider air a binary mixture. A comprehensive model was developed to determine cell performance under various operating condition and multiple cell geometries. The output of this model was used to optimize various physical features of the cell. Tests were performed on electrode supported solid oxide electrolysis cells at the Idaho National Laboratory. These cells were subjected to various operating temperatures and inlet steam mole fractions. Voltage vs. current density experimental data were collected and compared to computational data in order to validate the model.

Regulation of the human delta opioid receptor (hDOR) is implicated in the development of tolerance to chronic morphine (Zhu et al., 1999). In addition, DORs are promising analgesic targets for the management of chronic pain states such as inflammatory or neuropathic pain (Cahill et al., 2007). Therefore, in this study, we investigated multiple aspects of hDOR regulation, including receptor phosphorylation, beta-arrestin binding, receptor internalization, down-regulation and desensitization, using recombinant Chinese hamster ovary (CHO) cells expressing the wild-type or various mutant hDOR constructs. We found that structurally diverse delta opioid agonists regulate the hDOR by different mechanisms. We demonstrate that morphine is able to activate the initial step of the regulatory events, phosphorylation of S363, but due to requirements for simultaneous activation of multiple sites, morphine fails to promote beta-arrestin binding, receptor internalization and down-regulation. We also report that peptide delta opioid receptor agonists and a non-peptide agonist SNC80 differ in their ability to down-regulate the hDOR. Further differences in receptor phosphorylation, desensitization and beta-arrestin translocation between these two classes of full DOR agonists are reveled by truncation of the receptor's C-terminus or by mutation of the primary phosphorylation site, S363. Studies using the mutant receptors identify the C-terminus as the important domain for hDOR phosphorylation, beta-arrestin binding and down-regulation by both peptide and non-peptide agonists. S363 within the C-terminus is critically involved in receptor phosphorylation, desensitization and down-regulation, but not in beta-arrestin binding and receptor internalization. In contrast to peptide agonists, SNC80 is able to phosphorylate and activate secondary intracellular domain(s), in addition to the C-terminus, which participate in beta-arrestin recruitment and receptor desensitization and down-regulation. Therefore, agonist-specific differences were detected for multiple regulatory events between morphine, peptide agonists and SNC80. Differential agonist-mediated regulation of the human delta opioid receptor may be used to design pain therapy drugs with improved analgesic properties and minimal side effects.

Warm forming of aluminum alloys of has shown promising results for increasing the formability of aluminum alloy sheet. Warm forming is a term that is generally used to describe a sheet metal forming process, where part or all of the blank is formed at an elevated temperature of less than one half of the material’s melting temperature. The focus of this work is to study the effects of warm forming on Novelis X926 clad aluminum brazing sheet. Warm forming of clad aluminum brazing sheet, which is commonly used in automotive heat exchangers has not been studied. This work can be split into three main goals: i) to characterize the material behavior and develop a constitutive model, ii) to experimentally determine the effects of warm forming on deep drawing; and, iii) to create and validate a finite element model for warm forming of Novelis X926. For an accurate warm forming material model to be created, a temperature and rate dependant hardening law as well as an anisotropic yield function are required. Uniaxial isothermal tensile tests were performed on 0.5mm thick Novelis X926at 25°C (room temperature), 100°C, 150°C, 200°C, and 250°C. At each temperature, tests were performed with various strain rates between 7.0 E -4 /sec and 7.0 E -2 /sec to determine the strain rate sensitivity. Tensile tests were also performed at 0° (longitudinal), 45° (diagonal), and 90° (transverse) with respect to the material rolling direction in order to assess the anisotropy of the material. It was found that increasing forming temperature increases elongation to failure by 200%, decreases flow stress by 35%, and increases strain rate sensitivity. Barlat’s Yield 2000 yield function (Barlat et al., 2003a) and the Bergström work hardening law (van den Boogaard and Huétink , 2006) were found to accurately method model the material behavior. Warm deep drawing of 101.6 mm (4”) diameter cylindrical cups was performed using specially designed tooling with heated dies and a cooled punch. Deep drawing was performed on 228.6 mm (9“) and 203.2 mm (8”) diameter blanks of 0.5 mm thick Novelis X926. Deep drawing was performed with die temperatures ranging from 25°C to 300°C with a cooled punch. Teflon sheet and Dasco Cast 1200 lubricants were used in experiments. Different punch velocities were also investigated. 228.6 mm diameter blanks, which could not be drawn successfully at room temperature, were drawn successfully using 200°C dies. Increasing the die temperature further to 250°C and 300°C provided additional improvement in formability and reduced tooling loads. Increasing the punch velocity, increases the punch load when forming at elevated temperatures, reflecting the strong material rate sensitivity at elevated temperatures. A coupled thermal mechanical finite element model was developed using the Bergström hardening rule and the Yield 2000 yield surface using LS-DYNA. The model was found to accurately predict punch force for warm deep drawing using Teflon sheet as a lubricant. Results for Dasco Cast 1200 were not as accurate, due to the difficulties in modeling the lubricant’s behavior. Finite element simulations demonstrated that warm forming can be used to reduce thinning at critical locations, compared to parts formed at room temperature.

Little is known about the outward trafficking of receptor dimers from the endoplasmic reticulum to the plasma membrane, or the role that trafficking plays in assembly, targeting and specificity of receptor signalling. Bimolecular fluorescence complementation was used to follow prescribed receptor homo/heterodimers in Jurkat cells and clarify the trafficking itineraries those receptors follow to reach the plasma membrane. Chemokine receptors CXCR4 and CCR5 were chosen due to their implication in numerous pathologies including, HIV and cancer, and their ability to form homo and hetero-oligomers. This study demonstrates that although the individual receptors composing heterodimeric complexes are the same as in homodimeric complexes, the heterodimer traffics and signals independently of its constituent homodimers. The presence of CD4 affects the trafficking of CCR5 containing dimers but not the CXCR4 homodimer. These observations demonstrate the importance of considering receptor heterodimers as distinct signalling entities that should be more carefully and individually characterized.

Apelin, the endogenous ligand to the apelin receptor, is a small peptide involved with cardiovascular regulation. Using nuclear magnetic resonance (NMR) spectroscopy, I demonstrate that at low temperature, residues R6-L9 and G13-F17 of apelin are more structured than the rest of the peptide. I also study the interactions of apelin with sodium dodecylsulphate (SDS), dodecylphosphocholine (DPC) and 1-palmitoyl-2-hydroxy-sn- glycero-3-[phospho-RAC-(1-glycerol)] (LPPG) micelles. Apelin binds to SDS micelles through residues R6-L9, with structure being induced in this region as well as the C- terminus of the peptide. The binding to micelles along with the corresponding change in structure make it likely that apelin binds to the apelin receptor following the membrane catalysis hypothesis. NMR spectroscopy was used to determine the structure of the N- terminal tail and first transmembrane segment of the apelin receptor (AR55) in DPC micelles. AR55 has two disrupted helices from D14-K25 and from A29-K57. The second helix is the membrane spanning region of AR55 and has a significant kink located at N46. Mutagenesis of the apelin receptor and functional assays indicate that G42, G45 and N46 are essential for the proper trafficking and function of AR. In the N-terminal tail, the functionally critical residues E20 and D23 form an anionic face that could take part in initial binding of apelin to AR. The structure of AR55 was also determined in SDS micelles, LPPG micelles and a 1:1 water: 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) solution. Overall, the micelle spanning region of AR55 has a consistent structure with a kink near N46. The N-terminal tail of AR55 is more variable, having similar structures in the micelle conditions but being largely helical in 50% HFIP. NMR relaxation experiments indicate that the N-terminal tail of AR55 undergoes much more motion in LPPG micelles compared to SDS and DPC micelles. Finally, I created a program named MC-HELAN that characterizes the kinks that occur in protein helices. I used MC- HELAN to analyze all non-redundant membrane protein structures as of March 2010. Membrane protein helix kinks are remarkably common and diverse. Initial attempts to predict membrane protein kinks using only the protein sequence were unsuccessful.

The processes studied by nuclear engineers generally include coupled physics phenomena (Thermal-Hydraulics, Neutronics, Material Mechanics, etc.) and modeling such multiphysics processes numerically can be computationally intensive. A way to reduce the computational burden is to use spatial meshes that are optimally suited for a specific solution; such meshes are obtained through a process known as Adaptive Mesh Refinement (AMR). AMR can be especially useful for modeling multiphysics phenomena by allowing each solution component to be computed on an independent mesh (Multimesh AMR). Using AMR on time dependent problems requires the spatial mesh to change in time as the solution changes in time. Current algorithms presented in the literature address this concern by adapting the spatial mesh at every time step, which can be inefficient. This Thesis proposes an algorithm for saving computational resources by using a spatially adapted mesh for multiple time steps, and only adapting the spatial mesh when the solution has changed significantly. This Thesis explores the mechanisms used to determine when and where to spatially adapt for time dependent, coupled physics problems. The algorithm is implemented using the Deal.ii fiinite element library [1, 2], in 2D and 3D, and is tested on a coupled neutronics and heat conduction problem in 2D. The algorithm is shown to perform better than a uniformly refined static mesh and, in some cases, a mesh that is spatially adapted at every time step.

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The thesis describes development and optimization process of an inductively coupled coil corrosion potential sensor for long-term civil structure health monitoring remotely. This is of growing interest for decreasing the maintenance cost, reducing the deterioration significantly and increasing the safety. The thesis is organized accordingly introduction, circuit modeling of the sensor, optimization and fabrication of the sensors and the simulated and experimental results from new and existing civil structure. The two geometrical design, cylindrical shape and Printed Circuit Board (PCB) based sensor parts of this research and their encapsulation technique for long-term enduring in harsh and corrosive environment of the civil infrastructure is described in the thesis. Results of an accelerated corrosion test on an embedded cylindrical shaped sensor indicates that the corrosion potential can be monitored with less than 10 mV resolution with a sensor sensitivity of ~0.73 kHz/mV. The last part describes a novel technique for a PCB sensor to simulate the existing structure already contaminated with corrosive substances such as chlorides. Two encapsulation techniques, non-conductive epoxy sealed and PLEXIGLAS with air gap sealed embedded PCB sensors response are compared from the accelerated corrosion test on new and built-in civil structure. Finally, results from the accelerated corrosion tests using the two encapsulation techniques mentioned above demonstrate that the embedded sensor in an existing structure may take up to 60 days to see the significant corrosion with a sensor sensitivity of ~ 1.53 kHz/mV or ~ 1.63 kHz/mV respectively. Since chlorides take many years to diffuse into concrete used for civil structures these sensors will respond fast enough to be used in existing structures as well as in new structures.