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Using Potential Energy Surfaces of Diatomic Molecules to Determine the Bond Dissociation Energy via Computational Chemistry
Get PDFThe bond length along which two atoms vibrate can be altered in order to construct a potential energy surface used to determine the bond dissociation energy of a diatomic molecule. Carbon monoxide was initially used as the diatomic molecule of choice in this ChemCompute lab experiment. The bond length of carbon monoxide was altered in the range of .086 to .177 nm, and the electronic energy produced was recorded. A potential energy curve was constructed at these bond lengths until the molecule dissociated; a relative potential energy curve was then constructed. The equilibrium bond length, 0.113 nm, and the well depth (De”) were found, 692.539 kJ/mol. Using the force constant of 1902 N/m for carbon monoxide, the vibrational frequency (ve) was found to be 2169 cm-1 . The zero-point energy, which is the difference between the bottom of the well and the lowest possible vibrational level, was determined to be 1084 cm-1. The bond dissociation energy (Do”) for carbon monoxide was then found to be 669.6 kJ/mol with a 37.5% error. Using another set of molecules, sulfur monoxide (SO) and hydrochloric acid (HCl), equilibrium bond lengths of 0.135 and 0.128 nm, vibrational frequencies of 1685 and 3147 cm-1, and zero-point energies of 842.7 and 1574 cm-1 were found, respectively. To assess the accuracy of the calculations from ChemCompute further, the bond dissociation energy was also found for SO and HCl with a value of 242.9 kJ/mol and 53.4% error for SO and 24.60 kJ/mol with 94.5% error for HCl. As the number of bonds decreases between a diatomic molecule, the accuracy of the bond dissociation energy decreases. While being a useful tool in visualizing bond length and the potential energy surface for a diatomic molecule, due to these computational methods relying on experimentally determined values and the Gaussian basis set, the data produced is sometimes inaccurate in the determination of dissociation energies
Influence of Nutrient Contamination on Macroinvertebrate Communities in Two Tidal Freshwater Creeks
Get PDFFreshwater ecosystems are some of the most biodiverse on the planet, but they are threatened due to human actions resulting in habitat loss, pollution, and nutrient runoff. Macroinvertebrates can be used to measure the health of a freshwater system because different taxa have different tolerances to pollutants. However, the relationship between nutrient runoff and macroinvertebrates remains understudied. Accokeek Creek and Aquia Creek are two tidal freshwater streams in Stafford, VA. Accokeek Creeks drains a watershed containing the Crow’s Nest Natural Area Preserve and minimal development. Aquia Creek’s watershed is largely suburban. The objectives of this study were a) to examine differences in macroinvertebrate diversity between Accokeek and Aquia Creeks and b) to investigate the relationship between nutrient concentration and macroinvertebrate community assemblage. Because we expected nutrient levels to be higher in Aquia Creek, we hypothesized that Accokeek Creek would have higher macroinvertebrate biodiversity than Aquia Creek. In late spring 2021, habitat data and three macroinvertebrate samples were taken from six Accokeek sites and four Aquia sites. Two water samples and one sediment sample were collected from each Accokeek and Aquia site for nitrogen and phosphorus testing. A total of 1,874 macroinvertebrates across 25 taxa were identified with the most common taxa being Oligochaeta (n=954), Chironomidae (n=314), and Hydrobiidae (n=191). Shannon Diversity was significantly higher in Aquia Creek (1.418±0.096 mean±SE, n=10) than in Accokeek Creek (0.939±0.099, t(20)= -3.4, p=0.003, n=12). Orthophosphate levels were significantly higher in Aquia Creek (0.154mg/L±0.012) than in Accokeek Creek (0.065mg/L±0.008), t(20)= -6.3, p\u3c0.0001). Based on these results, our hypothesis was not supported. A positive relationship was found between orthophosphate level and Shannon Diversity [R2 =0.25, p=0.0104], which may be explained by increased vegetation associated with elevated orthophosphate levels. Further analysis will be done to examine the relationship between biodiversity and nutrient levels in the late summer months
Borderline Personality Symptoms and Relationship Threat: The Moderating Role of Perceived Parental Rejection
Get PDFIndividuals with borderline personality disorder (BPD) often perceive relationship threats more intensely, resulting in increased emotional reactivity. However, this link has never been examined with physiological measures in “real time,” nor has perceived parental rejection ever been investigated as a potential moderator of this link. To fill this gap, the present study induced romantic relationship threat, after which participants completed an emotional reactivity task while electroencephalography data were recorded. Results reveal that higher levels of BPD features were associated with increased emotional reactivity, indicated by larger late positive potential (LPP) amplitudes, to negative stimuli in the face of a romantic relationship threat. Results also indicate that perceived parental rejection moderates said link, in that individuals with high BPD features and high perceived parental rejection have decreased emotional reactivity to negative stimuli following a relationship threat. Findings have implications for treatment of BPD clients who have experienced parental rejection in childhood, as well as implications for couples’ counseling in the face of relationship threat
Abel Lake Water Quality: Trends over four decades
Get PDFFreshwater lake reservoirs are important not only for their unique beauty but also as a source of easily treatable water for human consumption. It is critical to monitor and protect these waters. Monitoring enables regulation and planning for correction of unusual measurements. After being monitored for 17 years of active water use, Abel Lake is now no longer routinely monitored, though it remains a water resource for future generations. New sampling was completed in 2022 to evaluate the lake’s current condition. Historical trends such as alkalinity had recorded at ranges from 24 to 28 mg/L while new data shows current levels are now ranging from 38 to 62 mg/L. Other interesting trends include measures of pH, turbidity, hardness, color, iron, and manganese. The changes recorded from while the plant was in operation today are likely caused by the consumption of carbon dioxide via algal photosynthesis, and seasonal leaf litter and suspended sediment inputs
Grumio Bacteriophage Genome Annotation
Get PDFBacteriophages, or phages, are virus particles which are only capable of infecting bacterial cells (Clokie et al.). These phages are of interest as a potential replacement for antibiotic therapies in cases of drug resistant bacterial infections (Sulakyelidz et al. 2001). One such phage, Grumio, was discovered and isolated at the University of Mary Washington. As a recently discovered phage there was very little known about it, such as the specific sequences of DNA responsible for its infection of certain strains of bacteria. By analyzing this genetic material, the genomic sequences responsible for the phages ability to infect certain strains of bacteria as well as other functions of the final virus particle may be discovered. To accomplish this, the complete sequence of DNA is analyzed and annotated using the program DNAMaster to provide a reference for future work of the notable features within the genome. This annotation includes the identification of likely gene sequences as well as assessments of these sequences for potential functions. The resulting final annotation of the bacteriophage genome will then be submitted to be included in the PhagesDB as a reference for future work with Grumio or other similar bacteriophages
Graph Embedded Term Rewrite Systems
Get PDFThe primary motivator of this research is attempting to extend the ability of cryptographic protocol analysis tool and prove security questions about a wider set of cryptographic systems. Many systems already work for “subterm-convergent” presentations. Many also work for specific examples of protocols that are beyond subterm-convergent. However, there is no syntactic definition of this “beyond subterm” or no classification of what systems. The resulting question is: Can we define a new form of beyond subterm-convergent Term Rewrite System (TRS) and prove it can be used to extend the ability of existing cryptographic protocol analysis methods? We begin finding our solution by first using notions of graph theory develop a new definition of graph-embedded relation on terms. Then, we extend the graph embedded notion on terms to term-rewrite systems. Next, we prove that these new “graph-embedded TRS” encompass the required properties of the cryptographic analysis systems. Finally, we prove that the protocol analysis systems work on the classes of graph-embedded TRS, namely that they have the local stability property. As a result of this research, we have developed a new form of graph-embedded term rewrite system. Additionally, we have proven several properties such as termination and that they differ from homeomorphic embedded systems. These properties were then used to show how graph-embedded term rewrite systems can be used to analyze cryptographic protocols, for example, by using local stability. In future work, we would like to explore more applications for graph-embedded term rewrite systems, as well as investigating if additional embedding properties such as topological embeddings are useful
Myokine Expression in a Myotonic Dystrophy Type 1 Cell Culture Model
Get PDFMyotonic dystrophy type 1 (DM1) is a multisystemic disease characterized by muscle weakening and wasting. DM1 is the most commonly diagnosed adult-onset muscular dystrophy, and skeletal muscle wasting is responsible for 60% of DM1 related mortality, although the mechanism responsible for the DM1 skeletal muscle wasting phenotype has not been concretely identified. DM1 is caused by expansion of CUG repeats in the 3′ untranslated region of the DMPK gene. Pervious research has suggested that myokines, signaling molecules typically involved in cell-cell communication, play a role in muscle wasting. Additionally, gene expression analysis of a mouse DM1 model identified elevated expression of specific myokines, including Cx3cl1. This project aimed to explore the role of myokines in DM1 related muscle wasting using a cell culture model. Using Lipofectamine 3000, the C2C12 mouse myoblast cell line was transfected with plasmids that express either human DMPK exons 11-15 including a 960 CUG repeat or a control plasmid that that express DMPK exons 11-15 with no CUG repeats. Differentiation was induced in half of the cells, and RNA was extracted from the cells at three timepoints: day 1, 3, and 5. Extracted RNA was assessed using qPCR to quantify Cx3cl1 expression. Unfortunately, the qPCR results did not indicate measurable expression of Cx3cl1, the primary target myokine of this project, in the transfected cells, despite expression of internal controls at all timepoints at comparable level. The immeasurable expression of Cx3cl1 could be due to the C2C12 cells’ inadequate expression of CUG repeats in the DMPK gene, as the cells potentially are not expressing long enough repeats to observe an effect. Further research that utilizes a different model, such as a mouse skeletal muscle or human myoblast cell culture model is required to determine the influence of myokines on DM1 pathology, as these models express repeat RNA for prolonged periods of time
Exploration of the Effects of Bond Length on the Potential Energy Curves for Diatomic Compounds
Get PDFBond dissociation energy (BDE) is the unique energy required to break a bond in a molecule into its respective atoms or molecular fragments. In this study, the theories behind harmonic and anharmonic oscillators, which address BDE of diatomic molecules, were employed to relate the length of a bond to its corresponding potential energy. A computational chemistry program was utilized to investigate the potential energies of diatomic hydrogen (H2), bromine (Br2), and hydrogen bromide (HBr). The diatomic molecules were found to obey Hooke’s law for harmonic oscillation at low energies, but as the energy increased with stretching the bond, deviations were observed due to anharmonicity because the restoring force was inequivalent to the displacement force. Instead of a harmonic parabolic shape, the potential energy curve followed a Morse potential function, approaching an asymptote representing the dissociation of the molecule into its constituent atoms at increased energies. The equilibrium bond length of dihydrogen was found to be approximately 75 pm, with an error of 1.16% from the literature value, 74.14 pm.1 Despite the accuracy of the computed bond length, the BDE for H2 was elucidated to be 1025 kJ/mol using the computational program, with a 135 % error from the literature value of 436 kJ/mol.1 In this presentation, an overview of these theories, the experimentation, and the major results will be provided for H2 and the other diatomic molecules
Execute the Office
No full textWhen Colin Rafferty moved to Virginia in 2008 he didn’t know much about the presidents, so he set out to read a biography of each one. What began as a personal project eventually turned into his new publication – a collection of experimental, genre-bending essays on every U.S. president
Resurrecting Gaelic: Modernity and Heritage Language Revival in Scotland in a Comparative Perspective
Get PDFMany people from across the world have little or no connection to their heritage languages. Whether this loss is caused by conquest, colonialization, or simply lack of parent-child transmission, many believe that they are missing an integral part of their cultural identity and want to reclaim the languages of their forebearers. There is wide debate about how, why, and if this linguistic reclamation and revitalization should happen because, in the face of modernity and language evolution, the best solutions are not always clear. What constitutes successful language revitalization in the modern world, and why does it happen? Gaelic in Scotland is a telling example