In this master thesis a small modular sodium-cooled metal-fuelled pool-type fast reactor design, called SPARC - Safe and Passive with Autonomous Reactivity control, has been designed. The long term reactivity changes in the SPARC are managed by implementation of the the Autonomous Reactivity Control (ARC) system, which is the novelty of the design. The overall design is mainly based on the Integral Fast Reactor project (IFR), which experimentally demonstrated the passive safety characteristics of a metal fuelled, sodium-cooled, pool-type reactor system. Whilst mimicking the passive safety features of the IFR, the vision of the SPARC design is a battery type reactor, which can operate with minimum interference from human actors. In this thesis, two reactor examples have been developed which operate using different fuel compositions. One reactor operates on recycled nuclear waste from today's nuclear power plants, and the other reactor operates on enriched uranium. Both reactors have a thermal power of 150 MW, and are meant to operate for 30 years without refuelling. The design was developed using the ADOPT software, and was simulated in Serpent. Using Serpent, criticality analyses were carried out which show that the ARC system is able to control the long term reactivity changes of the reactors.

Call number: LD2668 .T4 1978 L546 / Master of Science

Call number: LD2668 .T4 1985 T93 / Master of Science

Exaggerated cardiovascular reactivity (CVR) to stress has been implicated in the increased risk for cardiovascular disease (CVD) in individuals with posttraumatic stress disorder (PTSD), yet mixed results have been reported. The CVR research may have been confounded by underrepresentation of women, few studies using sophisticated cardiovascular measurement, and a lack of analyses of PTSD symptom clusters. The purpose of the present study was to examine if young civilian women (M ± SD = 29.89±7.33) with PTSD (n=17) demonstrate greater CVR than women with depression (n=12) or no mental illness controls (n=18), and to explore the relationships between CVR and PTSD symptom clusters. Participants were 56% Caucasian, 21% African American, 19% Hispanic, and 4% other. Systolic and diastolic blood pressure (SBP and DBP), heart rate (HR), and impedance cardiography derived cardiac output (CO) and total peripheral resistance (TPR) were utilized to examine CVR during speech preparation/delivery and math tasks. Between-group effects were observed during speech preparation - specifically, lower DBP reactivity for the PTSD group compared to the depression group (p < .05). Between-group effects were also evident during speech delivery, with a trend toward lower DBP reactivity for the PTSD group than the depression group (p <.08), higher CO reactivity for the PTSD group than controls (p <.01), and lower TPR reactivity for the PTSD group than the depression (p <.01) and control groups (p <.01). PTSD severity scores for DSM-IV-TR and DSM-5 were used as independent predictors of CVR in multiple regressions variables. The DSM-IV analysis did not provide significant associations. The DSM-5 yielded significant associations of avoidance and arousal clusters with SBP reactivity during math, a significant association avoidance with DBP reactivity during math, and significant associations of avoidance and arousal with HR reactivity during math. Further exploration of PTSD symptom clusters may provide a clearer picture of the relationship between PTSD/CVR. Higher reactivity and lower reactivity may both be associated with risk for CVD, albeit through separate mechanisms.

Research supports varied patterns of emotion-modulated startle (EMS) reactivity among depressed individuals. The purpose of this study was to examine whether these varied patterns can be explained by depression, empathic tendencies, and emotional stimuli. The EMS paradigm is a well-validated measure of emotion-modulated reactivity in which the magnitude of startle reflexes in reaction to acoustic stimuli are recorded while participants view pleasant, neutral, and negative images (Lang, Bradley, & Cuthbert, 1990). Young adults (N = 120; Mage = 19.54, SD = 1.41; 75% female) completed self-report rating scales of depression symptoms and cognitive and affective empathic tendencies and the EMS paradigm. Individuals with low depression, regardless of their cognitive (hp2 = .44 and .47) and affective empathic tendencies (hp2 = .49 and .36), and individuals with high depression and high cognitive and affective empathic tendencies (hp2 = .23, .46, respectively) exhibited the typical linear EMS reactivity pattern of increasing startle reflex magnitude from pleasant to neutral to unpleasant images. In contrast, individuals with high depression along with low cognitive and affective empathic tendencies exhibited blunted EMS reactivity patterns (hp2 = .000, .04, respectively). These findings indicate blunted EMS reactivity patterns only in depressed individuals who have low cognitive and affective empathic tendencies and are likely disengaged from emotional stimuli, thus suggesting variability among depressed individuals in motivational states that prime or inhibit the startle reflex.

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

Immunochemical reagents were characterized under carefully controlled laboratory conditions using conventional high performance liquid chromatography instrumentation. The stationary phase was prepared by attaching antigen molecules to an insoluble support through a covalent linkage. Experiments were carried out by introducing antibody molecules into the mobile phase and monitoring their interaction with the stationary phase. Monoclonal antibodies were employed because of their more homogeneous properties compared to polyclonal antisera. Radioisotopes were employed to study low level adsorption on the stationary phase. Recovery experiments were carried out in which it was possible to account for all of the material introduced into the mobile phase. Antibodies were purified over a preparative scale antigen affinity column following labeling to insure high immunoreactivity. Studied under normally dissociating conditions, irreversible adsorption of picomole amounts of protein on the antigen stationary phase was greater than on other ligand modified stationary phases. This accumulation decreased with repeated use of the affinity column. The present study provides a framework for evaluation of other immunoaffinity systems and demonstrates that reproducible recovery of immunologically active material in high yield is possible. Monoclonal antibodies labeled with fluorescein were different from unlabeled molecules in binding and physical characteristics. Computer simulations were used to describe binding behavior. Although fluorescein labels improve detection sensitivity over native protein absorbance, their use in this case decreased binding affinity significantly. Heterogeneity of affinity purified fluorescein labeled and unlabeled monoclonal antibodies was examined with two dimensional gel electrophoresis. In addition to increased charge heterogeneity in the labeled antibody fragments, both light and heavy chains possessed more negative character. These results agree with each other. Fluorescein contains a carboxylic acid group, and modification of antibody light chains may interfere with binding affinity. The number and location of labels covalently attached to antibodies must be carefully controlled to obtain maximum detection sensitivity and preserve immunoreactivity.

Cytochrome c was immobilized to several supports to study the effects of immobilization on the molecule and to serve as a model for the in vivo system. Immobilization was accomplished by covalent attachment of cytochrome c to the support surface, either Sepharose 6MB or glassy carbon. The effect of the coupling conditions on the covalent attachment reaction was studied with Sepharose 6MB. The reactive groups were monitored colorimetrically and were highly susceptible to hydrolysis. Correction for hydrolysis indicated that the covalent attachment reaction was first order with respect to reacted groups. Coupling conditions most affecting the amount of attached cytochrome c were the initial cytochrome c concentration, temperature, and pH. A detailed study of the resulting immobilized cytochrome c was conducted based on its three characteristic properties: spectra, oxidation reduction potential, and biological activity. The spectral properties demonstrated that no major conformational changes had occurred upon immobilization since the spectra were essentially the same. The redox potentials for most samples of immobilized cytochrome c loaded with different amounts of protein were found to be 20-25 mV lower than native cytochrome c (+ 270 mV). Two samples, the heaviest loaded, were approximately equal to the native protein suggesting that they may be least affected by immobilization. The biological activity measurements provide an indication of the ability of the molecule to function properly. The Michaelis constant (K(m)) for cytochrome oxidase and reductase with immobilized cytochromes c were significantly higher (20-400X) than the K(m) for soluble cytochrome c. The higher K(m)s reflect that about 1% of the immobilized cytochrome c is availble for reaction in agreement with distribution and exclusion studies. Correction of the immobilized cytochrome c K(m)s for available protein results in values similar to the soluble cytochrome c K(m). Immobilization of cytochrome c to glassy carbon was performed by two procedures employing a carbodiimide or 4-vinylpyridine as the coupling reagents. The former resulted in electrodes with higher specific activities and lower protein loadings than the latter. In both cases up to 60% of the immobilized protein was held by adsorption on the surface. Protein coverages were approximately 10⁻⁸ to 10⁻⁹ moles/cm² which corresponds to 100-800 layers.