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This thesis is concerned with the study of crystal structures by x-ray and neutron diffraction techniques, and also with the application of the symbolic addition method of solving crystal structures directly from the diffraction data. Chapter 1 contains a review of direct methods of phase determination in diffraction experiments, the first part of the chapter being concerned with the historical background of the topic and the second part with the practical details of the symbolic addition method as applied to both x-ray and neutron diffraction data. In Chapter 2, the crystal structure analysis of the stable free radical t-butylferrocenyl nitroxide is described, and the possibility of direct Fe...N or Fe...O bonding is discussed. The relative orientations of the two cyclopentadienyl rings are compared with the orientations of the cyclopentadienyl rings in other ferrocene derivatives, and the dimensions of the nitroxide radical are compared with those published for other nitroxide radicals. Chapter 3 describes the refinement of the structure of the 1:1 complex of hexahelicene with 4-bromo-2,5,7-trinitrofluorenone, and the resulting dimensions of the hexahelicene molecule are compared with those predicted from molecular-orbital and valence-bond calculations in which a planar molecule was assumed. In Chapter 4 the determination of the crystal structure of potassium tri-hydrogen di-succinate directly from neutron diffraction data is described and discussed; the refinement of the structure of potassium tri-hydrogen di-glutarate is described, and the structures of these 'super-acid' salts are discussed, in particular the dimensions of their hydrogen bonds. Chapter 5 describes the x-ray and neutron diffraction analyses of the crystal structure of the neutral salt a-picoline N-oxide hydrochloride monohydrate, and the structure is described in terms of the disproportionation of a neutral salt into an acid salt and a basic salt. Particular attention is paid to the discussion of the 'acid salt' part of the structure,the bichloride ion Cl-H-Cl-. In Chapter 6, the structure analyses of the p. nitrosoaniline derivatives 9-nitrosojulolidine and N,N-diethyl p-nitrosoaniline are described, and the extent to which quinonoid-type structures contribute to the resonance hybrids of these compounds is discussed. The dimensions of their nitroso groups are discussed and compared with those of other nitroso compounds. (The accuracy attained in the neutron analysis of the picoline salt was disappointing in relation to the chemical interest of this structure. It could have been improved had it been possible to use longer counting times).

Nonpoint stormwater runoff remains a leading threat to surface water quality in the U.S. Increased impervious surfaces, climate change, and increasing water demands put even more pressure on stormwater managers to improve stormwater management practices with regards to cost effectiveness, removal performance, and ecological sustainability. More effective BMPs can be designed by understanding the nature of pollutant runoff loads with respect to the hydrograph. Many studies have been performed on the first flush (FF) phenomenon (the assumption that the initial portion of a rainfall-runoff event is more polluted than the later portions). However, controversy remains on whether or not the first flush truly exists, which environmental factors influence a first flush, and how best to define the first flush phenomenon. The objective of this study as to evaluate the first flush occurrence in two small urban watersheds (differing in extent of impervious area) using multiple analytical methods and definitions previously published in the literature. The first watershed is 4.8 acres with 67% impervious roadway and the second watershed is 5.6 acres with 87% wooded land cover. Statistical tests were performed to analyze for site-specific correlations between first flush strength and rainfall characteristics (e.g. rainfall depth, peak flow rate, runoff volume, peak rainfall intensity, and antecedent dry period) and determine differences in FF strength between different land uses and pollutants. Furthermore, the FF study was utilized to perform an annual treatable load analysis in order to evaluate the effectiveness of two hypothetical BMPs sized to treat stormwater from the highly impervious watershed based on the 1.3 cm, 1.9 cm, 2.6 cm and 3.2 cm of rainfall water quality volumes. A year-long study captured stormwater samples from over 33 storm events and analyzed for TSS, turbidity, nutrients and heavy metals. Samples were collected using flow-based sampling frequencies that yield a more accurate quantification of pollutant mass transport throughout the storm event than time-paced sampling used in most of the previous first flush studies. For each collected storm, normalized cumulative pollutant load (L') and runoff volume curves (V') were generated for each pollutant with a minimum of seven discrete curve points to quantify the first flush effect and evaluate for first flush occurrence based on several published methods and definitions (e.g., max L'>V', max L'-V' > 0.2, and 80% of total load runoff in first 30% of total runoff volume). Linear regression analyses were performed to determine the first flush coefficient (b) for the power function L' = V'b to quantify the FF strength. Relationships between the first flush strength and rainfall characteristics were examined. Analysis of covariance (ANCOVA) was utilized to determine if FF strength (i.e. b-value) significantly differed between wooded and impervious watersheds, and a nonparametric ANOVA (Kruskal-Wallis test) was used to evaluate differences in FF strength among the pollutants within each watershed. As indicated by all the methods utilized in this study, most pollutants exhibit a slight FF effect on average but substantial pollutant loading still occurred in the latter portion of the storm's total runoff volume. Thus, to treat the majority of a storm's total pollutant load requires capturing almost the same fraction of runoff volume. Although the FF phenomenon was not dominant, this study did define a "most efficient" design volume (first 40% of runoff or approximately 1.3 cm of rainfall), which was where the fraction of total pollutant load was greatest compared to the fraction of total runoff volume. Of the rainfall characteristics analyzed, rainfall and runoff volume both inversely affected the FF strength of TSS and heavy metals on the impervious watershed. Although the runoff nature of orthophosphate (O-PO4) at the first portion of the storms did not have a first flush, the relative FF strength for O-PO4 actually increased with increasing rainfall or runoff. Land use did not influence the first flush strength of the pollutants except for Pb, which had significantly stronger FF effect on the more impervious watershed compared to the heavily wooded one. Disregarding the estimated pollutant load from a large 18.2 cm tropical storm, the 1.3 cm and 2.6 cm of rainfall design volumes could potentially capture and treat on average 64% and 82% of the annual runoff volume and 67% and 85% of the annual pollutant load for all the pollutants on the impervious watershed. Although stormwater BMPs designed to capture the first 2.5 cm of rainfall can potentially treat a substantial fraction of yearly pollutant load, this study suggests that in watersheds with limited and expensive land area it is more efficient to use multiple smaller BMPs near the source that capture the smaller, more frequent storms (1.3 cm of rainfall or less). Among all the stormwater BMPs currently utilized to reduce peak runoff volumes and remove contaminants from urban runoff, constructed wetlands have emerged as an optimal choice because of their high performance of water quality improvement and ecological benefits. Due to a stormwater wetland's high land requirement, however, they are often difficult to size properly in urban environments. This study also evaluated the pollutant removal efficiencies of a newly constructed flow-through stormwater wetland that is sized to only capture 20% of runoff generated by the recommended design storm in N.C. (first 2.5 cm of rainfall). The wetland was constructed in December 2006 as a retrofit to a failing level-spreader in order to repair a rapidly eroding head-cut between two stormwater outfall channels and the receiving stream. Following addition of the extended detention function, the undersized wetland has initially removed, on average, 71% of the TSS load, between 39% and 60% of the nutrient load, and 60% of the heavy metal load. For all the pollutants except TP and TKN, lower removal efficiencies were observed for the storms with flow bypass (5 out of 9 events since the extended detention function) on average as compared to the smaller events without bypass. When evaluated for all the sampled storms, event mean concentrations proved to be statistically lower at the outlet for all pollutants except Ti and V. For most pollutants, higher influent EMCs were observed for the storms with higher removal efficiencies. It is important to note, however, that these initial results are skewed by a small number of storms with low rainfall depths (median = 0.46 cm). With that considered, the average removal efficiencies are actually higher than predicted for the 1.3 cm design storm BMP. Undersized wetlands with "flow through" design might provide effective and efficient pollutant removals if designed to safely pass the larger storms. Longer term research will provide a more definitive evaluation.

Remains of late Miocene hominoids increasingly indicate both taxonomic and adaptive diversity. Understanding hominoid paleoenvironments may illuminate the selection pressures relevant to this diversity. Previous analyses of bovid ecomorphology have been applied to understanding hominoid environments. In this study, a new analysis of distal and complete bovid metapodials assigned to five habitats was conducted and applied to several fossil sites including Can Llobateres and Y0311 in the Siwaliks. An ecomorphological framework was also developed for hipparion metapodials and applied to many late Miocene fossil sites. The distal and complete discriminant models for bovid metapodials reported here performed between 3.8 and 4.1 times better than chance. Compared to prior discriminant models developed for the bovid femur (Scott et al, 1999; Kappelman, 1988), astragalus (DeGusta and Vrba, 2002) and metapodials (Plummer and Bishop, 1994) all results reported here resulted in more robust values of Press’s Q statistic and better performance when compared to chance. Habitat scores were developed for hipparions based mainly on metapodial length and the medial-lateral dimension of the metapodial diaphysis. These scores yielded paleoenvironmental interpretations congruent with those already published for well-sampled sites such as Höwenegg and provide important evidence regarding late Miocene paleoenvironments. In total, the results of this analysis indicate two general patterns relevant to late Miocene hominoids. Sites such as Can Llobateres and Rudabánya are marked by lower hipparion diversity, hipparions adapted to closed habitats, and suspensory, frugivorous hominoids. In contrast, a second pattern is evident for locality 12 of the Sinap Formation and Ravin de la Pluie where a diverse and likely abundant hipparion fauna including open-adapted and closed-adapted forms is associated with pronograde, hard object feeding hominoids.