The objective of the research in this thesis was to develop high-efficiency n-type silicon solar cells at low-cost to reach grid parity. This was accomplished by reducing the electrical and optical losses in solar cells through understanding of fundamental physics and loss mechanisms, development of process technologies, cell design, and modeling. All these technology enhancements provided a 3.44% absolute increase in efficiency over the 17.4% efficient n-type PERT solar cell. Finally, 20.84% efficient n-type PERT (passivated emitter and rear totally diffused) solar cells were achieved on commercial grade 239cm2 n-type Cz silicon wafers with optimized front boron emitter without boron-rich layer and phosphorus back surface field, silicon dioxide/silicon nitride stack for surface passivation, optimized front grid pattern with screen printed 5 busbars and 100 gridlines, and improved rear contact with laser opening and physical vapor deposition aluminum. This thesis also suggested research directions to improve cell efficiency further and attain ≥21% efficient n-type solar cells which involves three additional technology developments including the use of floating busbars, selective emitters, and negatively charged aluminum oxide (Al2O3) film for boron emitter surface passivation.

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This dissertation studies China’s energy policy since the “Go Out” strategy became the PRC’s “overarching national strategy”, having been put forward for the first time in the 5th Plenum of the 15th CPC Central Committee in October 2000 –despite having been de facto implemented since 1993. It focuses on the evolution of the PRC’s petroleum and biofuels policy from 2000 to 2010 and on the impact it has had on Brazilian and Argentine energy policy and exports of energy resources to China. The study adopts an asymmetrical interdependent perspective within a South-South Cooperation analytical framework to argue that the role these countries have played as suppliers of fossil energy resources (petroleum) to the PRC throughout the observed period –role that can be defined as having been relatively modest in spite of having ranked as China’s top South American oil suppliers for most of it– has considerable potential to become significantly more relevant in the future, through the diversification of their energy exports to China based on the combination of fossil fuels and renewable energy resources (biofuels). As regards the former, the study highlights the game-changing discovery of enormous ultra deep-water off-shore reserves in Brazil in 2007 and 2010 (Tupi-Lula and Libra, respectively, which are already turning Brazil into a major oil exporter) and of the gigantic shale energy formation of Vaca Muerta in Argentina in 2010. Regarding the latter, both Brazil and Argentina are leading producers and exporters of biofuels (sugar cane- based ethanol and soybean-based biodiesel, respectively). The remarkable progress that the PRC has made in the energy sectors of the analyzed countries –and in Latin America in general, showing the “asymmetry of attention” paid by China and the USA to the region is emphasized. The research highlights the increasing importance that renewable energy resources are having in Chinese energy policy, due to both energy security and environmental concerns. It argues that the addition of clean energy resources to their exports to the PRC would benefit Brazil and Argentina by allowing them to diversify not only their export baskets (by adding more products to their exports to China, with the plus that these would have value added) and export destinations (adding the growing Chinese market while simultaneously reducing these countries’ dependence on traditional biofuel destinations such as the EU and the USA), but would also have positive effects for China’s fuel supply mix, contributing to make China’s transition to a low-carbon economy (or, at least, lower-carbon) shorter – as well as positive spillovers in their industrial structures.

This study determined the effect of N-acetylcysteine (NAC) supplementation on recovery of strength following eccentric muscle injury. Female subjects (n = 21, age = 20.7 ± .10 yr, weight = 68.05 ± 10.3 kg, height = 1.69 ± .07 m) performed one bout of eccentric exercise involving the forearm flexor muscles. Subjects were given a placebo (food-grade cellulose; n = 10) or NAC supplement (10 mg·kg-1 bw·d-1; n = 11) for 7D prior to and 14D following the exercise bout. Maximal Voluntary Contraction (MVC) torque, muscle soreness, range of motion (ROM), and arm circumference were measured at pre-exercise, immediately post-exercise, and at 1D, 3D, 7D and 10D post-exercise. In addition, serum interleukin-6 (IL-6), serum creatine kinase (CK), and serum glutathione were measured. Subjects also completed a food frequency questionnaire to determine the antioxidant content of their diet. There was no difference in the loss and subsequent recovery of muscular strength between the placebo and NAC group immediately post-exercise (26.93 ± 6.4 vs. 24.95 ±9.4 Nm), 1D (27.83 ± 5.7 vs. 26.9 ± 8.5 Nm), 3D (38.35 ± 6.7 vs. 34.69 ± 10.2 Nm), 7D (46.9 ± 8.8 vs. 42.5 ± 11.8 Nm), or 10D (57.83 ± 11.7 vs. 52.92 ± 14.3 Nm) post-exercise (p = .274). In addition, there was no difference in muscle soreness (p = .752), arm circumference (p = .535), ROM (p = .539), serum CK (p = .449), serum glutathione (p = .967), or serum IL-6 (p = .360) at any time point. Scores on the food frequency questionnaire demonstrated that dietary antioxidant intake was not different between groups (41.04 ± 8.04 vs. 33.01 ± 12.6; p = .054). In conclusion, a bout of eccentric forearm flexor exercise resulted in muscle injury and a significant decrease in subjects’ ability to produce force. Supplementation with NAC had no effect on recovery of strength, arm circumference, ROM, serum CK, serum IL-6, or serum glutathione at any time point following the exercise bout. These results demonstrate that NAC has no effect on recovery of strength following eccentric muscle injury.

Glycosylation, the addition of sugar moieties to nascent proteins, is one of the most common posttranslational modifications. Glycosylation regulates protein structure, function and localization. Most cell surface proteins and secreted proteins are glycosylated by the addition of Asparagine(N)-linked glycans (N-glycans). Aberrant N-glycosylation is a well-accepted feature of malignancy and is a potential prognostic marker for some types of cancer. For example, increased expression of complex N-glycans has been detected in cancers of breast, colon and has been correlated with reduced survival of the patients. Therefore, understanding the role of N-glycosylation in malignancy could be beneficial for developing novel therapeutic and prognostic strategies. To examine the role of N-glycosylation in malignancy, we applied chemical biology and genetic approaches. First, we conducted a high throughput screen to identify compounds that could block L-PHA-induced cell death. Our screen identified the cardiac glycoside Na+/K+-ATPase inhibitors as novel inhibitors of N-glycosylation. Further analysis of N-glycans consistently confirmed that inhibition of Na+/K+-ATPase impairs the N-glycosylation, as well as migration and invasion. Interestingly, other studies have shown antimetastatic effects of cardiac glycosides in patients. Thus, our high throughput screen identified Na+/K+-ATPase inhibition as a novel strategy to target the N-glycosylation pathway. In addition, we used a genetic approach to investigate the role of N-acetylglucosaminyltransferase I (GlcNAc-TI/Mgat1) in malignancy. Knockdown of GlcNAc-TI decreased the cell-surface expression of complex N-glycans. By confocal microscopy, knockdown of GlcNAc-TI decreased cell surface expression of β1 integrins and increased their localization around the nucleus. Moreover, GlcNAc-TI knockdown decreased the migration and invasion of malignant cells. Next, we investigated the effect of GlcNAc-TI in an orthotopic xenograft mouse model of metastasis. GlcNAc-TI knockdown significantly decreased the lung colony formation of the highly metastatic PC3N7 human prostate cancer cell line in mice. Our results suggest an important role for GlcNAc-TI in tumor metastasis. Interestingly, breast cancer patients with lower expression levels of Mgat1 had lower risk of disease relapse after therapy. Thus, GlcNAc-TI plays an important role in cancer progression and metastasis and GlcNAc-TI inhibitors could have therapeutic benefits for cancer patients. Moreover, expression levels of GlcNAc-TI could be used as a prognostic marker in patients with cancer.

Measures of working memory capacity are associated with performance on a variety of cognitive tasks. A number of recent studies have provided evidence that training working memory can lead to improvements in fluid intelligence and performance on other untrained tasks. However, many of these studies suffer from design limitations. The aim of this study was to investigate the effects of working memory training on measures of fluid intelligence, reasoning, working memory, and attentional control by comparing a training group with an active control group. The training group improved more than the active control group on some, but not all outcome measures. Differential improvement for the training group was observed on fluid intelligence, working memory capacity, and response times on conflict trials in the Stroop task. In addition, individual differences in pre-training fluid intelligence scores and initial performance on the training task explain some of the variance in outcome measure improvements.

Nitrogen fertilization has the potential to significantly affect yield, nutrient concentration and removal and overall stand longevity of C4 grasses grown for bioenergy production. While most studies report that these grasses need little to no fertilizer inputs to maximize yield, no specific recommendations have been given for fertilizer requirements across a wide range of C4 perennial grass species, cultivars, harvest timings and N application rates. Two field trials were established in the summer of 2008 in Ridgetown and Elora, Ontario to compare 4 Miscanthus (M. sinensis and M. sacchariflorus crosses; Nagara-116 and Amuri-114, and Miscanthus x giganteus; M1 Select and Polish), 2 switchgrass (Panicum virgatum L.; Cave-in-rock and Shelter) and 2 big bluestem varieties (Andropogon gerardii Vitman; Prairie view and Southlow), 4 nitrogen fertilization rates (0, 40, 80, and 160 kg N ha-1) and 2 harvest timings (fall vs. spring harvest). Plots were harvested in the fall of 2009 and spring and fall of 2010. Yield response to N fertilization varied by location, species and year. In general, increasing N fertilization rates generated an increased yield response in all tested species. Different rates of N fertilization resulted in variable responses to N, P and K tissue concentrations and removal in switchgrass and Miscanthus. Tissue N concentrations and removal both increased with added N fertilization at both locations. In most cases N removal was the highest at the highest N application rate. Nitrogen concentrations were highest in the leaves and seed heads across species, N rates and locations. P and K concentrations and removal with increasing N fertilization in the whole plant and in individual plant parts did not follow clear trends in either Miscanthus or switchgrass in both locations. Delaying harvest to spring reduced yield at both locations by 35-42% and 62-65% for Miscanthus and switchgrass, respectively. Yield losses by delaying harvesting to the spring were increased with higher rates of N fertilization. Delaying harvesting decreased N, P and K concentration and removal in most grasses and locations.