Pressurized metered dose inhalers (pMDIs) are widely utilized to manage diseases of the lungs, such as asthma and chronic obstructive pulmonary disease. They can be formulated such that the drug and/or nonvolatile excipients are dissolved or dispersed in the formulation, rendering a solution or suspension formulation, respectively. While the formulation process for solution pMDIs is well defined, the formulation process of pMDIs with any type of suspended entity can be lengthy and empirical. The use of suspended drug or the addition of a second drug or excipient in a suspension pMDI formulation may non-linearly impact the product performance of the drug of interest in the formulation; this requires iterative testing of a series of pMDIs in order to identify a formulation with the most potential for success. One of the primary attributes used to characterize the product performance and quality control of inhaled medications is the residual aerodynamic particle size distribution (APSD) of the aerosolized drug. Along with clinical factors, formulation and device parameters have a significant impact on APSD. In this study, a computational model was developed using the principles of statistics and physical chemistry to predict the residual APSD generated by suspension pMDIs based on formulation, device, and raw drug or excipient substance considerations. The formulations modeled and experimentally evaluated consist of a suspended drug or excipient with/without a dissolved drug or excipient in a cosolvent-propellant system. The in silico model enables modeling a process that is difficult to delineate experimentally and contributes to understanding the link between pMDI formulation and device to product performance. The ability to identify and understand the variables that affect atomization and/or aerosol disposition , such as initial droplet size, suspended micronized drug or excipient size, and drug or excipient concentration, facilitates defining the design space for suspension pMDIs during development and improves recognizing the sensitive of the APSD is on each hardware and formulation variable. This model can later be applied to limit batch-to-batch variation in the manufacturing process and selecting plausible suspension pMDI formulations with quality design as the end goal.

The high and ever growing demand for electricity coupled with environmental concerns and a worldwide desire to shed petroleum dependence, all point to a shift to utilization of renewable sources of energy. The under developed nature of truly renewable energy sources such as, wind and solar, along with their limitations on the areas of applicability and the energy output calls for a renaissance in nuclear energy. In this second nuclear era, deliberately small reactors are poised to play a major role with a number of Small Modular Reactors (SMRs) currently under development in the U.S. In this work, an SMR model of the Integral Pressurized Water Reactor (IPWR) type is created, analyzed and optimized to meet the publically available performance criteria of the mPower SMR from B&W. The Monte Carlo codes MCNP5/MCNPX are used to model the core. Fuel enrichment, core inventory, core size are all variables optimized to meet the set goals of core lifetime and fuel utilization (burnup). Vital core behavior characteristics such as delayed neutron fraction and reactivity coefficients are calculated and shown to be typical of larger PWR systems, which is necessary to ensure the inherent safety and to achieve rapid deployment of the reactor by leveraging the vast body of operational experience amassed with the larger commercial PWRs. Inherent safety of the model is analyzed with the results of an analytical single channel analysis showing promising behavior in terms of axial and radial fuel element temperature distributions, the critical heat flux, and the departure from nucleate boiling ratio. The new fleet of proposed SMRs is intended to have increased proliferation resistance (PR) compared to the existing fleet of operating commercial PWRs. To quantify this PR gain, a PR analysis is performed using the Proliferation Resistance Analysis and Evaluation Tool for Observed Risk (PRAETOR) code developed by the Nuclear Science and Security Policy Institute at Texas A&M University. The PRAETOR code uses multi-attribute utility analysis to combine 63 factors affecting the PR value of a facility into a single metric which is easily comparable. The analysis compared hypothetical spent fuel storage facilities for the SMR model spent fuel assembly and one for spent fuel from a Westinghouse AP1000. The results showed that from a fuel material standpoint, the SMR and AP1000 had effectively the same PR value. Unable to analyze security systems and methods employed at specific nuclear power plant sites, it is premature to conclude that the SMR plants will not indeed show increased PR as intended.

No description available.

The steam generator plays a primary role in the safety and performance of a pressurized water reactor nuclear power plant. The cost to utilities is in the order of millions of Rands a year as a direct result of damage to steam generators. The damage results in lower efficiency or even plant shutdown. It is necessary for the utility and for academia to have models of nuclear components by which research and analysis may be performed. It must be possible to analyse steam generator performance for both day-to-day operational analysis as well as in the case of extreme accident scenarios. The homogeneous model for two-phase flow is simpler in its implementation than the two-fluid model, and therefore suffers in accuracy. Its advantage lies in its quick turnover time for development of models and subsequent analysis. It is often beneficial for a modeller to be able to quickly set up and analyse a model of a system, and a trade-off between accuracy and time-management is thus required. Searches through available literature failed to provide answers to how the homogeneous model compares with the two-fluid model for operational and safety analysis. It is expected to see variations between the models, from the analysis of the mathematics, but it remains to be shown what these differences are. The purpose of this study was to determine how the homogeneous model for two-phase flow compares with the two-fluid model when applied to a u-tube steam generator of a typical pressurized water reactor. The steam generator was modelled in both RELAP5 and in Flownex. A custom script was written for Flownex in order to implement the Chen correlation for boiling heat transfer. This was significantly less detailed than RELAP5’s solution of a matrix of flow regimes and heat transfer correlations. The geometry of the models were based on technical drawings from Koeberg Nuclear Power Plant, and were simplified to a one-dimensional model. Plant data obtained from Koeberg was used to validate the models at 100%, 80% and 60% power output. It was found that the overall heat transfer rate predicted with the RELAP5 two-fluid model was within 1.5% of the measured data from the Koeberg plant. The results generated by the homogeneous model for the overall heat transfer were within 4.5% of the measured values. However, the differences in the detailed temperature distributions and heat transfer coefficient values were quite significant at the inlet and outlet ends of the tube bundle, at the bottom tube sheet of the steam generator. In this area the water-level was not accurately modelled by the homogeneous model, and therefore there was an under-prediction in heat transfer in that region. Large differences arose between the Flownex and RELAP5 solutions due to difference in the heat transfer correlations used. The Flownex model exclusively implemented the Chen correlation, while RELAP5 implements a flow regime map correlated to a table of heat transfer correlations. It was concluded that the results from the homogeneous model for two-phase flow do not differ significantly when compared with the two-fluid model when applied to the u-tube steam generator at the normal operating conditions. Significant differences do, however, occur in lower regions of the boiler where the quality is lower. We conclude that the homogeneous model offers significant advantage in simplicity over the two-fluid model for normal operational analysis. This may not be the case for detailed accident analysis, which was beyond the scope of this study. / Thesis (MIng (Nuclear Engineering))--North-West University, Potchefstroom Campus, 2013.

The steam generator plays a primary role in the safety and performance of a pressurized water reactor nuclear power plant. The cost to utilities is in the order of millions of Rands a year as a direct result of damage to steam generators. The damage results in lower efficiency or even plant shutdown. It is necessary for the utility and for academia to have models of nuclear components by which research and analysis may be performed. It must be possible to analyse steam generator performance for both day-to-day operational analysis as well as in the case of extreme accident scenarios. The homogeneous model for two-phase flow is simpler in its implementation than the two-fluid model, and therefore suffers in accuracy. Its advantage lies in its quick turnover time for development of models and subsequent analysis. It is often beneficial for a modeller to be able to quickly set up and analyse a model of a system, and a trade-off between accuracy and time-management is thus required. Searches through available literature failed to provide answers to how the homogeneous model compares with the two-fluid model for operational and safety analysis. It is expected to see variations between the models, from the analysis of the mathematics, but it remains to be shown what these differences are. The purpose of this study was to determine how the homogeneous model for two-phase flow compares with the two-fluid model when applied to a u-tube steam generator of a typical pressurized water reactor. The steam generator was modelled in both RELAP5 and in Flownex. A custom script was written for Flownex in order to implement the Chen correlation for boiling heat transfer. This was significantly less detailed than RELAP5’s solution of a matrix of flow regimes and heat transfer correlations. The geometry of the models were based on technical drawings from Koeberg Nuclear Power Plant, and were simplified to a one-dimensional model. Plant data obtained from Koeberg was used to validate the models at 100%, 80% and 60% power output. It was found that the overall heat transfer rate predicted with the RELAP5 two-fluid model was within 1.5% of the measured data from the Koeberg plant. The results generated by the homogeneous model for the overall heat transfer were within 4.5% of the measured values. However, the differences in the detailed temperature distributions and heat transfer coefficient values were quite significant at the inlet and outlet ends of the tube bundle, at the bottom tube sheet of the steam generator. In this area the water-level was not accurately modelled by the homogeneous model, and therefore there was an under-prediction in heat transfer in that region. Large differences arose between the Flownex and RELAP5 solutions due to difference in the heat transfer correlations used. The Flownex model exclusively implemented the Chen correlation, while RELAP5 implements a flow regime map correlated to a table of heat transfer correlations. It was concluded that the results from the homogeneous model for two-phase flow do not differ significantly when compared with the two-fluid model when applied to the u-tube steam generator at the normal operating conditions. Significant differences do, however, occur in lower regions of the boiler where the quality is lower. We conclude that the homogeneous model offers significant advantage in simplicity over the two-fluid model for normal operational analysis. This may not be the case for detailed accident analysis, which was beyond the scope of this study. / Thesis (MIng (Nuclear Engineering))--North-West University, Potchefstroom Campus, 2013.

Bis(dimethylamino)-2-(4-methoxyphenyl)naphthalene (3) and 1,8-bis(dimethylamino)-4-diphenylphosphonaphthalene (5b) were synthesized as ESI-active analogues of the common organometallic ligands η6-anisole and triphenylphosphine. The water-soluble phosphine, sodium triphenylphosphine monosulfonate, was re-purposed as an ESI-active ligand. Its solubility in organic solvents and amenability to electrospray ionization was improved by replacing Na+ with the non-coordinating bis(triphenylphosphine)iminium cation. A new sample introduction method named PSI (pressurized sample infusion) was developed for the continuous infusion of air/moisture-sensitive samples into the mass spectrometer. The flow rate can be determined using a modified version of the Hagen-Poiseuille equation, and the ability of PSI (coupled with an ESI tag) to give quantitative kinetic data is demonstrated. A method for maintaining a dry, air-free ESI source is described for the analysis of highly reactive samples. The above developments were applied to the study of the copper-free Sonogashira (Heck alkynylation) reaction. The proposed active catalyst (Pd(0)L2, where L = PPh3 or 7) was observed, and its reactivity with iodomethane in the gas phase was determined to be less than that of Pd(0)L. Nevertheless, Pd(0)L2 is extremely reactive and even oxidatively adds dichloromethane (t1/2 = 10.7 min at 40 °C). Under standard reaction conditions intermediates corresponding to oxidative addition and transmetallation were detected, and coordination of base to palladium was observed for secondary amines but not triethylamine. Reductive elimination was achieved in the gas phase for a series of para-substituted aryl iodides with phenylacetylene, and the slope of the resulting Hammett plot (ρ) was -0.5. No evidence for the previously hypothesized anionic mechanism was observed. Simultaneous kinetic analysis of charged substrate, products and intermediates in the copper-free Sonogashira reaction was conducted using PSI-ESI-MS and high quality, information rich data for each species over time was obtained. In the absence of protons, reductive elimination is rate-limiting and the rate of reaction is relatively high. In the presence of protons (a byproduct of the reaction), transmetallation is rate-limiting and the rate of reaction is much slower. The use of a strong base was shown to improve the efficiency of the reaction, and an experimentally-derived catalytic cycle for the copper-free Sonogashira reaction is proposed. / Graduate

No description available.

Thesis (Ph. D.)--University of North Texas, May, 2007. / Title from title page display. Includes bibliographical references.

Thesis (M.S.)--University of North Texas, May, 2008. / Title from title page display. Includes bibliographical references.

Os hidrocarbonetos policíclicos aromáticos (HPA) representam hoje grande preocupação à comunidade científica devido a sua comprovada ação cancerígena e mutagênica, assim tornam-se necessárias metodologias mais eficientes para suas determinações. O presente trabalho desenvolveu a técnica de extração por líquido pressurizado com a etapa de clean-up simultânea a extração, com sílica e alumina como adsorventes dentro da cela do equipamento ASE-350. A metodologia desenvolvida foi comparada com a tradicional extração por Sohxlet através de material de referência certificado. A extração por Soxhlet, apesar de eficiente, mostrou-se dispendiosa pelo gasto enorme de tempo, solvente e adsorventes quando comparada a extração por líquido pressurizado. De maneira geral a extração por líquido pressurizado apresentou-se mais vantajosa que a tradicional extração por Soxhlet. A eficiência da metodologia desenvolvida também foi testada através de quatro diferentes tipos de solos brasileiros fortificados com solução padrão de HPA. Os solos utilizados foram dos seguintes locais: Nova Lima MG, Lavras MG, Casimiro de Abreu RJ e Luiz Eduardo Magalhães BA. Todos possuíam características granulométricas e químicas diferentes entre si. Dois solos foram classificados em latossolos vermelhos, um em vermelho-amarelo e um em planossolo. Houve diferença significativa na eficiência de recuperação de alguns HPA quando comparados os quatro tipos de solos, já para outros HPA não evidenciou-se influência da tipologia do solo / Polycyclic aromatic hydrocarbons (PAH) are now a great concern to the scientific community due to its proven carcinogenic and mutagenic action. Therefore more efficient methodologies become necessary for its determinations. This research developed the technique of extraction by pressurized liquid with the clean-up step simultaneous to the extraction, i.e., the soil sample is extracted as the clean-up occurs. For this silica and alumina adsorbents was used in the ASE-350 equipment cell. For the study four different types of Brazilian soils with their well-defined characterizations were used. The soils used were from the following locations: Nova Lima - MG, Lavras - MG, Casimiro de Abreu - RJ and Luiz Eduardo Magalhães - BA. All of them had different soil gradation and chemical characteristics. The soils were classified as red oxisols, red-yellowish oxisols and planosols. There was significant difference between the recovery efficiency of some PAH in the four soil types, as for other HPA showed up no influence of soil type. The developed methodology was compared to traditional Sohxlet extraction by certified reference material (CRM). The Soxhlet extraction, although effective, has proved costly for large expenditure of time, adsorbents and solvent when compared to pressurized liquid extraction. In general the pressurized liquid extraction was more advantageous than traditional Soxhlet extraction. The developed methodology efficiency was also tested through four different Brazilian soil types spiked with standard PAH solution. The soils used were from the following locations: Nova Lima - MG, Lavras - MG, Casimiro de Abreu - RJ and Luiz Eduardo Magalhães - BA. All of them had different soil gradation and chemical characteristics among themselves. Two soils were classified as red oxisols, one as red-yellowish oxisol and one as planosol. There was significant difference among the recovery efficiency of some PAHs when the four soil types were compared; as for other HPA showed up no evidence of soil type influence