My research interests have always focused on the field of environmental chemistry. In particular, my work has concentrated on the prevention or remediation of anthropogenic pollution using experimental and computational methods. As an M.S. student, I studied the use of naturally occurring sulfate-reducing bacteria to treat acid mine drainage (AMD) contaminated groundwater in situ. AMD, which often contains elevated concentrations of toxic heavy metals, pose a significant health threat that can be expensive to treat. In situ bioremediation techniques, such as those used in my research, represent an inexpensive way to treat these contaminants, but they are more sensitive to environmental factors. During my Ph.D. work I used high-level ab initio computational methods to investigate the kinetic rate parameters that govern specific pathways in the combustion and atmospheric decomposition of traditional and emergent fuel sources. Following my Ph.D., I worked as a research consultant for King Abdullah University of Science and Technology (KAUST) on determining the kinetic and thermodynamic parameters for specific fuel components, again using computational methods. Finally, during my post-doctoral work at the National Institute of Standards and Technology (NIST), I have been analyzing the high temperature kinetics (~1000 K) of methyl radical and hydrogen atom addition to unsaturated hydrocarbons using both computational and experimental single-pulse shock tube methods. These reactions are important pathways in the combustion of certain biofuels. By pairing the two methods we have been able to produce truly reliable results.
My work at Cabrini University involves the kinetic and thermodynamic investigation of hydrocarbon fuels and pollutants in the gas phase. The studies concentrate on the prevention of anthropogenic pollution using ab initio and DFT methods to determine the oxidation mechanisms under combustion and atmospheric conditions. The work focuses on assessing the viability of potential biofuel candidates through gas phase kinetics studies.
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Project 1 - Biofuels:
The Federal Aviation Administration (FAA) has recently expressed interest in funding research in aviation-grade biofuels. This will require the development of parameters and characteristics of fuels, both as individual molecules and complex blends, which will enable the evaluation of potential fuel sources. Research projects in this area consist of determining the reaction pathways of traditional and biofuel components, such as esters, alkenes and furanic compounds, under both combustion and atmospheric conditions using high level computational methods. These studies will use the Gaussian09 suite of programs along with reaction modeling software such as ChemRate to determine the thermodynamic and kinetic properties of these compounds, their products and reaction intermediates. The kinetic and thermodynamic parameters will allow for the determination of reliable rate parameters that can then be used by both the atmospheric and combustion modeling communities. Many of the compounds that would be viable aviation biofuel components will also be useful as ground transportation fuels.
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Project 2 - Hydrofluoroalkane and alkene oxidation
Chlorofluorocarbons (CFC) were once widely used for a variety of purposes due to their non-reactive nature, until Rowland and Molina determined that high energy UV light in the stratosphere is capable of breaking the C-Cl bond. The resulting Cl radical catalytically decomposes ozone. This process lead to the formation of the ozone hole over the Antarctic and the Montreal protocols in 1987, which reduced the use of and eventually lead to the ban of CFCs. Instead, researchers replaced one of the halogens with a hydrogen thereby making the molecules easier to be removed in the troposphere. However, these hydrochlorofluorocarbons (HCFC) were still making it up into the stratosphere and leading to further destruction of the ozone layer. To prevent the release of chlorine radicals into the stratosphere, the chlorines in the HCFCs were replaced with hydrogen, leading to the production of hydrofluorocarbons (HFC). While the lack of chlorine atoms means that the HFCs will not lead to the destruction of the ozone layer, they have since been found to be potent, long lived greenhouse gases (with lifetimes of ~100s of yrs). To address this problem, hydrofluoroolefins (HFO) were introduced, which due to their double bond are more susceptible to tropospheric decomposition. Unfortunately, little work has been done on what the intermediate species in the HFOs oxidation mechanism will be and what their IR absorption profile will be.
Project 3 - Antioxidants
Oxidative stress and reactive oxygen species (ROS) have been implicated in several physiological issues, including heart failure, cancer, and both Parkinson’s and Alzheimer’s diseases. ROS can enter the body either through exposure to airborne pollutants, such as ozone, or through in vivo processes like the Fenton reaction.11 Antioxidants are believed to remove ROS by scavenging radicals through electron transport, radical addition, or abstraction reactions. By analyzing the similarities and differences in the antioxidant mechanisms of these substances with a wide array of ROS and other radical species, this project will develop guidelines to predict what other compounds may also exhibit antioxidant properties. Some of the known antioxidants that I am interested in studying are: caffeine, theomobromine (found in chocolate), vitamin C, resveratrol (found in red wine), and anthocyanins (color pigments found in many plants).
Project 4 - 3D-printed equipment for undergraduate labs.
In the field of physical chemistry, it is often difficult to have undergraduates perform more advanced kinetics experiments. Often equipment such as stop/continuous flow reactors and temperature controlled cuvette holders that are required to perform rapid, accurate kinetics experiments are prohibitively expensive for use in an undergraduate lab setting, particularly at a small liberal arts college. However, with the recent development of small scale additive manufacturing devices (3D printers), a new avenue for curriculum development has opened up. Initial work in this area has involved the development of a continuous flow system that can fit in a quartz cuvette and allow for the premixing of reagents while sitting out of the path of the light source.
Project 5 - Virtual and Augmented Reality in Chemistry Education
Molecular models help students bridge the divide between the two dimensional pictures we as chemists use to represent molecules on paper and the three dimensional images we visualize when we see them. These physical models are themselves simplified representations of the molecules. They are often rigid and lack the ability to show the more dynamic behaviors of molecules (e.g., electron densities, vibrational modes, variations in bond distances, etc.). Advances in computational power over the last two decades has enabled the incorporation of computational chemistry software into the undergraduate curriculum. The importance of this is evident in the 2008 alterations to the ACS guidelines for an ACS certified undergraduate degree, which were amended to include the requirement that the college/university have the ability to perform computational chemistry calculations and that the students should use computational software as part of their coursework. The visualization software that is often paired with the computational allows the representations of chemicals to become more dynamic, however, they are currently limited to a 2D representation on a computer screen thereby eliminating the tactile, hands-on interaction of the physical molecular models. These screen-based models also require a certain degree of spatial ability, though due to the ability to rotate the image this requirement is less than a more traditional paper representation.
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