One of the central concerns of computational chemistry is that of efficiency (i.e. the development of methodologies which will yield increased accuracy of prediction without requiring additional computational resources – RAM, disk space, computing time). Though the equations of quantum mechanics are known, the solutions to these equations often require a great deal of computing power. This dissertation primarily concerns the theme of improved computational efficiency (i.e. the achievement of greater accuracy with reduced computational cost). Improvements in the efficiency of computational chemistry are explored first in terms of the correlation consistent composite approach (ccCA). The ccCA methodology was modified and this enhanced ccCA methodology was tested against the diverse G3/05 set of 454 energetic properties. As computational efficiency improves, molecules of increasing size may be studied and this dissertation explored the issues (differential correlation and size extensivity effects) associated with obtaining chemically accurate (within 1 kcal mol-1) enthalpies of formation for hydrocarbon molecules of escalating size. Two applied projects are also described; these projects concerned the theoretical prediction of a novel rare gas compound, FKrOH, and the mechanism of human glutathione synthetase’s (hGS) negative cooperativity. The final work examined the prospect for the parameterization of the modified embedded atom method (MEAM) potential using first principles calculations of dimer and trimer energies of nickel and carbon systems. This method of parameterization holds promise for increasing the accuracy of simulations for bulk properties within the field of materials science.

In recent years numerous complexes have been reported in which olefins were chelated to transition metals.Ever since the generally regarded first olefin complex, Zeise's salt (32) KPt(C2H43, the interest in this field of organometallic chemistry has expanded to several families of olefinic ligands and metals like palladium(II), platinum(II) copper(I), silver(I), and more recently vanadium and titanium The nature of the bonding of olefins to metal atoms seemed to involved the interaction between pi electrons in the unsaturated molecule and the hybrid orbitals of the metal rather than a localized sigma bonds between the metal atom and a particular carbon atom. The metal was complexed to a hydrocarbon which possessed a surplus of electrons. The direct overlap of a sigma orbital of the metal anad the p-orbital of the carbon atom formed a sigma type bond. The ligand carbon atom donated a surplus bonding pi-p electrons to a vacant sigma orbital of the metal while at the same time the excess negative charge was released back to the olefin from from a pi-d orbital of the metal to an empty antibonding pi-p orbital of the carbon atom. Dewar (9) illustrated this point by molecular orbital diagram. (See figure B) [see PDF file for Formula] The metal to olefin bond consisted of two parts: (a) overlap of the pi electron density of the olefin with sigma type acceptor orbital on the metal atom and (b) a "back-bonding" resulting from the flow of electron density from filled metal dxy or other dπ - pπ hybrid orbitals into antibonding orbital on the carbon atom. A schematic diagram of platinum olefin complexes can be shown as: [see PDF file for Formula] It was the intention of this research to increase our understanding of these stable diolefin complexes. In particular, the occurrence of rearrangement upon complexation of certain ligands to most likely a more stable configuration posed an interesting project. They syntheses of diolefin complexes provided an establishment of good technique and verification of reported data. The program of study was concentrated on the complexation of cyclic diolefins with primarily palladium(II) and platinum(II) chloride.

The objective of this thesis was to study theoretically the enrichment of hydrocarbon fuels with aluminum powder for an open-hearth furnace.

In-situ oil sands operations have been the dominant method of bitumen extraction in Canada since 2012; however, research on contaminants attributed to this method is limited in the peer-reviewed scientific literature, compared to that of open-pit mining. The Cold Lake oil sands region operates using exclusively thermal in-situ extraction techniques, raising the issue of whether oil sands activity is resulting in petroleum hydrocarbon (PHC) contamination in the absence of open-pit mines, upgraders, refineries, tailings ponds, and other bitumen processing operations. The lack of baseline contamination levels prior to oil sands development hampers debate on contamination from the oil sands industry. We address this shortcoming by using regional lake sediment cores to characterize petroleum hydrocarbons and trace their origin within the Cold Lake oil sands deposit. Petroleum hydrocarbons are hydrophobic compounds that bind to sediments, therefore persisting and accumulating in aquatic environments. This thesis examines historical levels of polycyclic aromatic hydrocarbons (PACs), petroleum biomarkers, and n-alkanes in radiometrically dated sediment cores collected from the depocenter of lakes within the Cold Lake heavy oil field. We used alkylated PACs and a suite of petroleum biomarkers to evaluate in-situ operations as potential petroleum-derived contamination sources. We predicted that similarly to open-pit mining, concentrations of PHCs in lake sediments would increase with industrial activity corresponding to proximity from in-situ operations. Like open-pit regions, alkylated PACs in Cold Lake sediments were elevated when compared to unsubstituted parent PACs and were significantly enriched in lake sediments deposited after the onset of oil sands operations. These findings imply that in-situ oil sands activity is driving the enrichment; however, diagnostic ratios and pyrogenic indices confirm a strongly pyrogenic origin in both pre-industrial and more recent sediments. When compared to a Cold Lake bitumen sample, the principal components driving PHC enrichment do not resemble bitumen. Likewise, diagnostic ratios of petroleum biomarkers and n-alkanes do not support bitumen as a significant source of hydrocarbons. PHC inputs in lake sediments are instead from terrestrial vegetation and plant waxes. These findings suggest that bitumen is not significantly contributing to petroleum hydrocarbon enrichment to lakes within the Cold Lake oil field; however, emissions from in-situ activity (natural gas burning, diesel trucks, seismic line cutting etc.) is increasingly abundant in more recent sediment. With >80 % of Canadian bitumen reserves requiring in-situ techniques for extraction, this thesis provides the first assessment of the spatial and temporal relationship between contaminant loading and proximity to in-situ oil sands operations. Additionally, this study allows for the environmental implications of open-pit mining operations to now be compared to that of in-situ techniques.

No description available.

No description available.

No description available.

A grass phytoremediation field study was initiated in July 1997 at the site of a former railroad tie facility that used creosote for tie preservation. The site is contaminated with polycyclic aromatic hydrocarbons (PAHs). A test matrix consisting of 36 planted (clover, fescue and rye grasses) and unplanted cells was established. The focus of the study was to evaluate PAH remediation in fertilized plots that were unplanted or seeded with clover, fescue or rye. Samples were collected from a depth of 15 to 21 cm, and the six most prevalent PAHs, acenaphthene, fluorene, phenanthrene, fluoranthene, pyrene and chrysene were quantified. Data from four sampling periods, t=0, 9, 12 and 17 months is presented. At t=9 months, substantial loss of the five lowest molecular weight (LMW) PAHs had occurred, and the loss was attributed to natural attenuation. During the first 9 months, below average precipitation at the site delayed grass root development. Between t=9 and 12 months, above average precipitation was recorded and this appeared to accelerate chrysene removal rates in both the unplanted and planted cells; however, the rate was higher rate in the planted cells. Similarly, fluoranthene and pyrene degradation seemed to be enhanced in the fescue and rye cells. Over the last 8 months of the study, acenaphthene, fluorene and phenanthrene concentrations approached constant, minimum levels suggesting additional removal will be limited. PAH compounds with higher solubility correlated to decreased constituent soil concentrations. Additional sampling was initiated at t=17 months to compare PAH concentrations with depth. This was done because the observed root mass changed significantly with depth. Samples were taken at two additional depths 10 to 15 and 32 to 38 cm. Increased removal of fluoranthene and pyrene was observed in the uppermost zone, suggesting a role for plants in remediation of these 4 ringed PAHs. / Master of Science

The patterns, stoichiometry, and kinetics of microbial benzene, toluene, p-xylene, m-xylene, and o-xylene degradation by a denitrifying activated sludge consortium was investigated in a sequencing batch reactor (SBR) receiving a mixed waste. After six months of acclimation, toluene and m-xylene were routinely degraded to below detection. Both toluene and m-xylene could serve as sole carbon and energy sources. The removal of o-xylene was also possible; however, its transformation was dependent upon gratuitous metabolism during toluene degradation. Benzene and p-xylene were recalcitrant throughout the study. The first order decay coefficient (b) of the denitrifying biomass was determined to be 0.016 ± 0.006 h⁻¹ on a theoretical oxygen demand (thOD) basis. The true growth yields (Y) for the biogenic and toluene/m-xylene components of the mixed waste were determined to be 0.41 ± 0.02 and 0.35 ± 0.04 mg thOD biomass per mg thOD substrate, respectively. The Monod parameters, qmax and KS, for toluene ranged from 0.059 to 0.14 mg toluene/mg protein/h and 0.84 to 6.9 mg/L, respectively. For m-xylene, the qmax and KS parameters ranged from 0.034 to 0.041 mg m-xylene/mg protein/h and 0.28 to 3.7 mg/L, respectively. Some of the variation observed between kinetic experiments was attributed to the different accumulation levels of the denitrification intermediate nitrite (NO⁻) and the inhibitory effects of its conjugate acid, nitrous acid (HNO₂). Other evidence suggested that part of the variation was also due to a continuous acclimation and refinement towards higher affinity toluene- and m-xylene-degrading enzyme systems within the biomass. / Master of Science

The problem was to study the behavior of several hydrocarbons when they were subjected to ultraviolet light of 2536 Å in the presence of mercury vapor.