Class of 2015 Abstract / Objectives: To determine if a change in the amount of sodium bicarbonate (NaHCO3) in 5 different IV solutions will help prevent phenytoin from falling out of solution (i.e. precipitating). Our working hypothesis is that the stability of the phenytoin solution will change with different IV solutions and will increase with increasing the amount of sodium bicarbonate. Methods: A constant amount of phenytoin injection solution was mixed with a constant amount of one IV solution per beaker. Different amounts of alkalizing agents were then added to each phenytoin and IV mixture. Precipitation of the mixtures was observed every 30 minutes for 4 hours, then again in 24 hours. Results: When different IV solutions were added to the phenytoin and alkalizing agent mixture , the pH of the mixture dropped from 10 to 9 independent of the amount of alkalizing agent present in the mixture. All phenytoin mixtures precipitated within 60 minutes; 0.9% NaCl and phenytoin mixture being the one with the most delayed precipitation. Conclusions: Based on the result of this experiment, we rejected both of our specific aim hypotheses. Our hypothesis is rejected because the stability of the phenytoin solution will not change by using different IV solutions or by changing the amount of sodium bicarbonate.

The environmental impact and sustainability of irrigation with coal-mine water was investigated from an agricultural point of view on different coal-mines in the Republic of South Africa. Field trials were carried out on a commercial and plot scale, on sites that could offer a range of soil, crop, weather conditions and water qualities such as gypsiferous, sodium sulphate and sodium bicarbonate waters. Crop production under irrigation with gypsiferous mine water is feasible on a field scale and sustainable if properly managed. No symptoms of foliar injury due to centre pivot sprinkler irrigation with gypsiferous water were observed. The presence of high Ca and Mg in the water suppressed plant uptake of K. This could be corrected by regular application of K containing fertilizers. The bigger problem experienced was waterlogging due to poor site selection, especially during the summer months. The problem is not related to the chemistry of the gypsiferous water used for irrigation. Pasture production with Na2SO4 rich mine effluent was also feasible, at least in the short term, but would need a well-drained profile and large leaching fraction to prevent salt build up. Forage quality was not affected by the Na2SO4 water used. NaHCO3 water was of very poor quality for irrigation and is not recommended for irrigation. Salt tolerant crops that are not susceptible to leaf scorching can be produced with this water, but only with very high leaching fractions and careful crop management. Regular gypsum application will be required to prevent structural collapse of the soil. Most of the salts applied will leach from the soil profile, and will probably need to be intercepted for treatment or reuse. The Soil Water Balance (SWB) model was validated successfully. The model predicted crop growth, soil water deficit to field capacity and soil chemistry reasonably well, with simulated results quite close to measured values. Soluble salts have to be leached from the soil profile, so that crop production can be sustainable, but will externalize the problem to the receiving water environment. To assess the environmental impact of irrigation with coal-mine water, it is valuable to develop a tool that can assist with prediction of offsite effects. SWB was validated for runoff quantity and quality estimations, and was found to give reasonable estimates of runoff quantity and quality. SWB also predicted the soil water and salt balance reasonably well. This gives one confidence in the ability of the model to simulate the soil water and salt balance for long-term scenarios and link the output of SWB to ground and surface water models to predict the wider impact of large scale irrigation. This will also link the findings of this work to other research oriented towards the management of mine water and salt balances on a catchment scale. It will also help authorities make informed decisions about the desirability and consequences of permitting mine water irrigation on a large scale. Irrigation with gypsiferous mine water can be part of finding the solution to surplus mine water problems. Appropriate irrigation management of mine water is essential for the long-term sustainability of irrigation. / Thesis (PhD)--University of Pretoria, 2009. / Plant Production and Soil Science / unrestricted

Articular cartilage has a low propensity for self-repair, due to which 27 million people are affected by osteoarthritis every year in North America. The current repair techniques used for cartilage defects possess flaws that reduce long-term clinical success. Tissue engineering carries with it the promise of engineering hyaline-like cartilage with physical and biochemical properties, similar to that of native cartilage. This being said, the primary objective of my project was to engineer clinically relevant sized articular cartilage constructs. To achieve my objective, first, I investigated the effect of continuous culture on cartilaginous tissue growth. Constructs grown under continuous media flow significantly accumulated more collagen and glycosaminoglycan, and displayed a stratified morphology, similar to that found in native cartilage. The second goal was to further increase chondrocyte proliferation, and extracellular matrix (ECM) accumulation. To achieve this, constructs were grown in a bioreactor with media supplemented with 14 mM sodium bicarbonate (NaHCO3). Constructs cultivated in the bioreactor with NaHCO3 supplementation exhibited a significant (p<0.05) increase in ECM accumulation (a 98-fold increase in glycosaminoglycans and a 25-fold increase in collagen content), cell proliferation (a 13-fold increase), and thickness (a 28-fold increase) compared to all other conditions (static and reactor without NaHCO3 supplementation). The third goal was to engineer cartilage constructs with as little cells as possible, reducing donor site morbidity. From the results obtained, it was evident that the monolayer constructs outperformed all the other constructs (pellet, biopsy, and minced). The final goal was to understand the underlying reason for the increased proliferation. First, I investigated if there were any differences present in intracellular pH (pHi) and intracellular buffering capacity. Second, I determined the role of extracellular pH (pHe) on cell proliferation. In an effort to accurately achieve this, I, for the first time, have reported on measuring pHi of chondrocytes while still in culture (2D and 3D cultures) using a confocal microscope. This study demonstrated the importance of extracellular environments, such as pHe, extracellular buffering capacity, and the presence of carbon dioxide and bicarbonate ions for chondrocyte proliferation. / Thesis (Ph.D, Chemical Engineering) -- Queen's University, 2012-10-30 19:19:32.026