Chemistry Commons^™

A Non-Destructive Analytical Technique Used For Analyzing A Variety Of Glassware Samples In Hopes To Determine Their Elemental Composition Based Off Their Qualitative And Quantitative Data Results., Angela Scarpa

Spring Showcase for Research and Creative Inquiry

In this study, XRF analysis was used to examine and identify specific glassware samples, exported from remote locations, in hopes to determine any correlation between the glass samples being tested. During experimentation, there were 41 glass samples and 3 glass standards that were examined and quantitatively analyzed to determine the elemental compositions of all samples. To ensure optimal sensitivity of these different materials, four methods were utilized to confirm accurate data is collected and to improve all quantitative data results. These four methods contain distinct experimental factors and were purposely selected due to their specific current, voltage, filter, time, and …

Chemical Analysis Of An Herbal Opioid, Lauren Johnson

Spring Showcase for Research and Creative Inquiry

Different chromatography techniques were used to analyze the concentration of an active component, mitragynine, in kratom samples. The analysis also compared three different extraction methods, one using ultrasonification, the other two using a commercial at home espresso maker. Using gas chromatography mass spectrometry, and high performance liquid chromatography, comparisons between key compounds in the substances were determined and concentrations of mitragynine within the samples were calculated.

Raman Spectroscopy Using A Monolithic Spatial Heterodyne Raman Spectrometer For Planetary Exploration, Abigail M. Waldron

Theses and Dissertations

Raman spectroscopy is a vibrational technique that provides detailed molecular and structural information for organic and inorganic molecules and minerals, and is uniquely suited for spacecraft applications, in the search for chemical indicators of life. This is why NASA sent two Raman spectrometers to Mars on the Mars 2020 Perseverance rover, as part of the SuperCam and SHERLOC instruments. The Raman spectrometers on Perseverance are conventional dispersive instruments that have been engineered to survive the harsh conditions of spaceflight. Future missions could benefit from smaller, more robust designs, especially missions to the Jovian planets, Jupiter and Saturn, their moons, asteroids …

Cis-Trans Isomerism In Single Molecule Electronic Devices, Tinsae Alem

Spring Showcase for Research and Creative Inquiry

We investigated the switching properties of cis-trans isomers of azobenzene for single molecule electronics. Although the cis-trans isomerization leads to structural changes within the molecule, the current flow is found to depend mainly on the relative position of the electrodes. The on/off ratio was determined to measure the performance of these isomers as switches. Different cis-trans isomers were studied to compare results.

The Analysis Of Heavy Metals In Samples Of Honey Using X-Ray Fluorescence And Anodic Stripping Voltammetry, Mia Arrieta, Kaleigh Beale

Spring Showcase for Research and Creative Inquiry

A daunting reality is haunting scientists as Colony Collapse Disorder (CCD) is declining bee population in the United States (1). A concrete conclusion as to why CCD is happening remains unclear but extensive research and studies are leaning towards a toxic component in honey to bees called hydroxymethylfurfural (HMF) (1). HMF has been a culprit in question for a while but researchers are still on the fence as to whether it should be concluded as such. It is theorized that HMF is formed in very warm temperatures and catalyzed by a metal in honey; manganese (1). Manganese is one of …

Water Quality Assessment Of Farmville, Va, Meghan Hall

Spring Showcase for Research and Creative Inquiry

In Farmville, some people drink tap water, but others choose only to drink filtered or bottled water. Some blame this on taste, and others say the mineral content affects their skin from sinks and showers. I propose to conduct an analysis of water hardness and chloride, nitrate, and lead levels of water from various sources in Farmville, Virginia. To measure each parameter, an EDTA titration was carried out to test for water hardness, anodic stripping voltammetry was conducted to detect lead, ion-selective electrode was used to measure chloride, and a modified Griess reaction was carried out to measure nitrate levels. …

Chemistry Meets Art: Instrumental Analysis At The Lcva, James Rakes, Mia Arrieta, Kaleigh Beale, Adonel Grubb

Spring Showcase for Research and Creative Inquiry

This project is an ongoing collaboration between the Longwood chemistry program and the Longwood Center for the Visual Arts. The demonstration shows the capabilities of the X-ray fluorescence spectrophotometer as a non-destructive elemental analysis technique. Our class visited the LCVA to analyze several pieces in their art collections. We were able to utilize the XRF instrument to analyze the elemental composition of glass and metal, painted pottery and porcelain, oil paintings, and metals. This project lays the groundwork for further research using X-ray fluorescence for non-destructive chemical analysis.

Characterization Of Uranium, Lead, And Rare Earth Element Pollution In Natural Soils And Sediments, Hope Rasmussen

Civil and Environmental Engineering Theses and Dissertations

Heavy metals in the environment add to the global burden of pollution, negatively impacting public health and ecosystem resilience. This study included projects regarding uranium (U), lead (Pb), and rare earth elements (REE) in natural samples, due to their known toxicity, ubiquity, and relevance in context to recent pollution trends. The first project focused on testing the potential of using a hydroxyapatite product as a remediation solution for U-contaminated groundwater and soil at an EPA Superfund site. The results showed that the U was sequestered in a highly crystalline mineral form within the solids, guiding the EPA to specify the …

Synthesis Of A Novel Pyrrole Family As Potential Anti-Cancer Agents, Sang T. Truong, Jeffrey A. Hansen

Student Research

A one-step selective reaction was developed to synthesize a novel pyrrole family (20 different members) from a keto-epoxide and several aromatic amines at room temperature in 3h. When substituting aromatic amine with aliphatic amines or inorganic bases, furan derivatives were produced selectively. The kinetic behavior of the reactions and structure of the products were characterized by nuclear magnetic resonance spectroscopy. The results showed that our reaction is selective with high yields (> 85%). To understand the selective formation of pyrrole and furan, we conducted computational experiences to study the mechanisms of the primary reaction and its competitor using Density Functional …

Biophysical And Structural Studies On Telomeric G-Quadruplexes From Tetrahymena Thermophila, Dana Beseiso , '21

Senior Theses, Projects, and Awards

G-quadruplexes (GQs) are non-canonical DNA structures composed of stacks of stabilized guanine tetrads (G-tetrads). GQs are highly diverse structures that can be categorized by their strand directionality, number of G-tetrads, and loop types among other parameters. Due to their high guanine content, GQs are expected to fold in regions such as telomers or oncogene promoters. They are thus firmly established as biologically viable targets for the development of anticancer therapeutics. In order to harvest GQs’ therapeutic potential, extensive structural studies are required to elucidate the structures’ diverse topologies alone and in complex with selective ligands. Towards this goal, this thesis …

Use Of Anthraquinone Derivatives And Methods Of Efficient Syntheses, Alex Crespo

Senior Honors Theses

While the bromination of aromatic compounds is a well-researched topic, AQ and hydroxy substituted AQ derivatives, with two carbonyl groups acting as strong deactivators for electrophilic substitution, are notoriously difficult to brominate.¹¹ Although there are well defined ways to brominate an AQ or hydroxy substituted AQ dating back to 1921,¹² in order to synthesize more complex AQ derivatives, a method for halogenating AQ derivatives already bonded to more complicated or unstable functional groups is needed in order for the compound to carry out desirable activities. This represents an area of great need in research. The purpose of this …

Hydrogen-Bonded Clusters: A Study Of The Elusive Anisole-Ammonia And Anisole-Water 1:1 Complexes, John Lawrence Loman

Master's Theses (2009 -)

The hydrogen bond is one of the most important and versatile interactions found in most subsets of chemistry and biology. This interaction is responsible for reactions and characteristic properties of the systems in thereof. This interaction is just one of several available non-covalent interactions that can occur and over the past several decades of molecular spectroscopy studies, the definition of the hydrogen bond has become broader compared to the “classic” definition. To accurately study the hydrogen-bonding in these systems can be quite challenging due to the size and complexity of the molecules involved, as well as the other interactions that …

Synthesis Of Composites From Cellulose, Chitosan, And Ciprofloxacin Hci Encapsulated In Sporopollenin Capsules, Mark Mitmoen

Master's Theses (2009 -)

In order to be effective dressings for the treatment of infected wounds in the battlefield, it is essential that composite materials made from the biopolymers Cellulose and Chitosan contain broad-spectrum antibiotic drugs. These drugs must first be encapsulated into microcapsules in order to protect them from the manufacturing process, ensuring that they remain in a usable form in the final product. Here we demonstrate the successful encapsulation of Ciprofloxacin HCl into Sporopollenin Exine Capsules (SEC) to produce Cipro@SEC, followed by incorporation of Cipro@SEC into a polymer composite consisting of a mixture of Cellulose and Chitosan dissolved in 1-butylmethylimidazolium chloride, an …

Biochemical Analysis Of Dual T-Loop Rna Motifs That Perform Shape Recognition Of The Trna Elbow, John Aparicio Aguirre

Master's Theses (2009 -)

T-loops are highly abundant, structurally conserved five nucleotide motifs that facilitate long range intra- and intermolecular interactions and function to stabilize the tertiary fold of RNA. Interlocked or dual T-loop motifs provide additional thermodynamic stability and perform long-range docking of other RNA molecules. Dual T-loop RNA structures are present within the multi-turnover ribonuclease P-based ribozyme, the ribosome, and the bacterial tRNA-sensing riboswitch genetic element. In all three systems, a dual T-loop structure recognizes TYC/D-loop region of tRNA. Interestingly, sequence conservation at specific positions in the T-loops suggest a conserved interlocked RNA architecture. While X-ray crystallography provides insight into the putative …

Development Of Mqct Method For Calculations Of Collisional Energy Transfer For Astrochemistry And Planetary Atmospheres, Bikramaditya Mandal

Dissertations (1934 -)

A mixed quantum/classical methodology and an efficient computer code, named MQCT, were developed to model molecular energy transfer processes relevant to astrochemical environments and planetary atmospheres and applied to several real systems. In particular, the rotational energy transfer in N2 + Na collisions was studied with the focus on quantum phase, differential cross-sections, and scattering resonances, and excellent agreement with full quantum results was found. For H2O + H2, detailed calculations were carried out with the focus on allowed vs. forbidden transitions between the ortho/para states of both collision partners. Again, excellent agreement with full quantum calculations was achieved. Calculations …

Molecular Basis Of Xenobiotic Metabolism And Resistance In Tetranychus Urticae, Leily Daneshian

Theses and Dissertations

Invasive pest species are a major cause of crop loss around the world and adversely affect the agricultural industry. We are focusing on Tetranychus urticae (two-spotted spider mite; TSSM), which is a polyphagous pest that targets more than 1100 plant species. The TSSM alone causes a loss of roughly $1.6 billion per year globally due to acaricide resistance. It is developing resistance to most acaricides due to rapid growth and reproduction. Therefore, new acaricides are needed to combat TSSM resistance and infestation [1]. To address this problem, four enzymes of TSSM, intradiol ring cleavage dioxygenases, a glutathione S-transferase, a β …

Reversing The Regioselectivity Of Indole Addition To Cyclic Unsymmetrical Oxyallyl Cations: Construction Of Diaryl Quaternary Centers, Thomas Davis Curry Ii

Honors Capstones

No abstract provided.

Fate Of Persistent Contaminants And Emerging Algal Toxins In Drinking Water And The Environment, Danielle Christine Westerman

Theses and Dissertations

Population growth and global climate change has resulted in the degradation of pristine water sources, causing issues like saltwater intrusion, persistent harmful algal blooms, and drought from population growth. Future reliance on alternative sources of drinking water to is expected globally, therefore, nontraditional sources of drinking water are becoming increasingly vital sources of potable water around the world. For example, desalination (typically by reverse osmosis), despite its high energy demands and high cost, is being utilized all over the world to meet drinking water demand. Wastewater reuse, the additional treatment of wastewater to produce drinking water, either directly or indirectly, …

Studies Of The Chemistry Of Pentaruthenium Carbido Carbonyl Cluster Complexes With Aldehydes, Azobenzene And Alkynes, Humaiara Akter

Theses and Dissertations

Polynuclear metal carbonyl complexes serve as the bridging model between heterogeneous catalysis and homogeneous catalysis for the activation of small molecules. Ru5(m5-C)(CO)15 has been found to exhibit superior reactivity due to its unusual polynuclear metal geometry. possibilities of interconversions of ligand bonding modes, and the formation of the electronically unsaturated metal species. C-H activation in aldehydes and azobenzene of pentaruthenium cluster complexes is described in chapters 2 and 3 respectively. The formation of new hydrocarbyl zwitterions and C – C coupling ethyne to the carbido carbon in the complex, and the alkyne insertion reactions with pentaruthenium cluster complexes are described …

Cationic Metallo-Polyelectrolytes: Synthesis And Application In Self-Assembly And Mechanochemistry, Yujin Cha

Theses and Dissertations

In this dissertation, cationic metallocene-containing polyelectrolytes were investigated for the construction of nano-objects by CDSA and the mechanical force-responsive polymer. The self-assembly behavior and mechanically induced polymer deformation were characterized and discussed.

In Chapter 1, the overall background and recent development of metallocene-containing polymers as well as their applications in self-assembly and polymer mechanochemistry were introduced. Primary research objectives were described.

The first section of the dissertation on the CDSA of cationic metallocene-containing block copolymers was provided in Chapter 2. The preparation of PCL-b-PCoAEMAs was achieved through ring-opening polymerization (ROP) of ε-caprolactone and reversible addition-fragmentation chain-transfer (RAFT) polymerization of cobaltocenium …

Sparse Modeling For Predicting Class Assignments For Trace Forensic Evidence, Dayla Christine Rich

Theses and Dissertations

Numerous disciplines in forensic science utilize various types of spectral data when analyzing evidence. Spectral techniques are particularly critical for the analysis of trace evidence, as these methods are normally non-destructive. Preserving evidence, especially trace evidence, is of high priority in a forensic laboratory setting. Once a piece of evidence has been fully consumed, no more analyses can be performed. Typically, visual comparison, or spectral overlay, is performed to compare questioned samples (evidence) to standards or knowns. However, such an approach may not be optimal in distinguishing the subtle, yet highly important, discriminating characteristics present in the spectra. As statistical …

Effect Of Oil And Gas Extraction On Disinfection By-Product Formation In Drinking Water, Dallas Graham Abraham

Theses and Dissertations

Certain industrial processes, such as energy extraction and utilization, generate massive amounts of wastewater with various geogenic and synthetic contaminants. Oil and gas wastewaters are characterized by elevated halide levels, particularly geogenic bromide and iodide. Concentrations in produced wastewaters have been reported as high as thousands of mg/L of bromide and tens of mg/L of iodide. Large volumes of these wastewaters are stored, transported, and disposed of, potentially impacting drinking water sources. Because conventional wastewater treatment fails to remove halides, oil and gas wastewater disposal, even after treatment, facilitates the formation of brominated and iodinated disinfection by-products (DBPs) at downstream …

Biophysical Characterization Of The Par-4 Tumor Suppressor: Evidence Of Structure Outside The Coiled Coil Domain And Interactions With Platinum Chemotherapeutics, Andrea Megan Clark

Chemistry & Biochemistry Theses & Dissertations

Prostate apoptosis response-4 (Par-4) is an apoptosis-inducing tumor suppressor protein. Full-length Par-4 has previously been shown to be a predominantly intrinsically disordered protein (IDP) under neutral conditions, with significant regular secondary structure evident only within the C-terminal coiled coil domain. However, IDPs can gain ordered structure through the process of induced folding, which often occurs under non-neutral conditions. Previous work has shown that the Par-4 leucine zipper, which is a subset of the C-terminal coiled coil domain, is disordered under neutral conditions, but forms a dimeric coiled coil at acidic pH. Increase in ionic strength was also shown to increase …

Evaluating The Role Of The Stringent Response Mechanism In Clostridioides Difficile Survival And Pathogenesis, Astha Pokhrel

Chemistry & Biochemistry Theses & Dissertations

The human pathogen Clostridioides difficile is increasingly tolerant of multiple antibiotics and causes infections with a high rate of recurrence, creating an urgent need for new preventive and therapeutic strategies. The stringent response, a universal bacterial response to extracellular stresses, governs antibiotic survival and pathogenesis in diverse organisms but has not previously been characterized in C. difficile. This dissertation explores the ability of C. difficile to mount the stringent response. The bacteria encode a full-length, canonical bifunctional Rel/Spo Homolog or RSH enzyme. C. difficile RSH is incapable of utilizing GTP as a substrate but readily synthesizes putative 5’-pGpp-3’ alarmones. …

Computational And Experimental Investigation Into The Determinants Of Protein Structure, Folding, And Stability In The Β-Grasp Superfamily, John T. Bedford Ii

Chemistry & Biochemistry Theses & Dissertations

Elucidating the mechanisms of protein folding and unfolding is one of the greatest scientific challenges in basic science. The overarching goal is to predict three-dimensional structures from their amino acid sequences. Understanding the determinants of protein folding and stability can be facilitated through the study of evolutionarily related but diverse proteins. Insights can also be gained through the study of proteins from extremophiles that may more closely resemble the primordial proteins. In this doctoral research, three aims were accomplished to characterize the structure, folding and unfolding behavior within the β-grasp superfamily. We propose that the determinants of structure, stability, and …

Conservation Of Polyester-Urethane Magnetic Audio Tapes And Discrimination Of Textile Fiber Dyes Using Spectroscopy And Chemometrics, Nilmini Hemanthika Ratnasena

Theses and Dissertations

This dissertation explores and discusses conservation of magnetic audio tapes and discrimination of fiber dyes employing spectroscopic techniques and chemometrics.

Conservation of polyester urethane magnetic audio tapes has become a major challenge since they are susceptible to degradation via hydrolysis. The world’s modern cultural history is vastly recorded in this media, and now conservationists need a non-destructive technique to determine the playability status of these tapes. Once conservationists identify degraded tapes, they can be subjected to the baking process. This process temporarily reverses hydrolysis and provides enough time to digitize tapes, preserving information for future generations. The first three chapters …

Automating And Implementing Complex, Multistep Sample Preparation Processes To Generate Reproducible Proteomic And Phosphoproteomic Data, Brian Todd Mullis

Theses and Dissertations

Phosphorylation is the most common post-translational modification that occurs within the cell and is intricately involved in many biological processes. It is important to understand the roles that protein kinases and phosphatases play by mapping protein phosphorylation as many disease states stem from aberrant signaling events. With the advent of modern mass spectrometry (MS), researchers are now provided with more complex phosphorylation patterns from thousands of proteins in each mass spectrometric analysis. Further developments in quantification techniques, such as stable isotope labeling with amino acids in cell culture (SILAC) and label-free quantitation, have allowed researchers to reliably quantify changes to …

Development Of A Liquid Biopsy: Using A Synthetic Lectin Array For The Detection Of Cancer, Mary Grace Hollenbeck

Theses and Dissertations

Cancer is the second leading cause of death worldwide with 9.6 million deaths in 2019. It is well known that early detection of cancer often leads to a better prognosis. However, due to drawbacks associated with current cancer screens (i.e. invasiveness, high false positive and negative rates) new or updated early detection methods are needed. Chapter one overviews current breast, colon, and prostate detection methods and the drawbacks associated with them. Additionally, this chapter presents an alternative detection method that utilizes an array of boronic acid functionalized synthetic lectins. We describe the development and progression of this array and show …

Molten Alkali Halide Salt-Flux Crystal Growth And Physical Property Determination Of Complex Oxides And Chalcogenides Supported By First Principles Density Functional Theory Calculations, Mohammad Usman

Theses and Dissertations

The primary objective of this dissertation is to inform the reader about more thansixty new materials with potentially attractive physical properties obtained via molten alkali halide flux methods as X-ray diffraction quality crystals. Flux crystal growth carries several advantages over other synthetic methods, including low reaction temperatures and straightforward post-reaction workup. This dissertation consists of 11 chapters, including an introductory chapter, which are organized into two parts, each corresponding to the general structure type of the family of oxides and chalcogenides being investigated. Part 1, which encompasses chapters 2–6, is dedicated to the discussion of crystal growth of complex chalcogenides …

Characterization And Hydrogenation Activity Of Supported Palladium Particles, Narayan Acharya

Theses and Dissertations

In this project, the hydrogenation activity of palladium (Pd) particles supported on different carbon and oxide supports was investigated. Supported Pd particles were prepared using strong electrostatic adsorption (SEA) technique, which is known to produce metal particles with narrow and uniform distribution. The scanning transmission electron microscopy (STEM), X-ray diffraction (XRD), and chemisorption methods were used to characterize the Pd particle size in this project. The Pd particles on different supports were annealed at a specific temperature, and the particle size was studied as a function of annealing temperature. Propylene hydrogenation to propane was conducted in a flow reactor to …