2020 Chemistry Capstone Symposium
The 2020 Chemistry Capstone Symposium is virtual this year due to COVID-19. Students have prepared recorded versions of their presentations for viewing by internal audiences. Their talk titles and abstracts are listed below.
We are all disappointed not to be able to have our usual in-person celebration of our students and their work. At the same time, we have been very impressed by their extreme determination and persistence in this challenging and unprecedented time. They have been real troopers.
Way to go, class of 2020! We congratulate all of you on your hard work and accomplishments!
A-G
Competition between molecules: A co-crystal study of nitrile and amide functionalized compounds and applications to cavitands
Carson J. Bergstrom, Senior Capstone Seminar
A molecular library consisting of triazoles and benzotriazoles, functionalized with amides and nitriles in various substitutions was synthesized. We subsequently attempted to co-crystallize these eight compounds with a variety of di-acid and pyrimidine co-formers using solvent assisted grinding and analyzed them using infrared (IR) spectroscopy. Our results indicate that with a 1:1 stoichiometry, the success rate for the formation of co-crystals with nitrile-containing compounds is 90% (54/60). In contrast, none of the co-formers formed co-crystals with amide containing compounds in a 1:1 stoichiometry, whereas by increasing the amide:co-former ratio to 2:1, the success rate increases to 92% (55/60). The results are believed to be due to interference of the homomeric forces present in amides which prevent the formation of heteromeric co-crystals until the reaction is saturated with co-former. We then synthesized and studied host-guest interactions between halogen bond donors and a benzyl-(1,2,4-triazole) functionalized macrocycle compound, c-hexyltetra(4-benzyl-(1,2,4-triazole))cavitand. Results showed a 4:1 guest:host ratio using UV-vis titration techniques. This study showed the power of the amide homomeric interactions and our ability to tune co-crystal formation by increasing co-former stoichiometry. It also enhances understanding of triazole functionalization on cavitands as a halogen bond acceptor and suggests the use of c-hexyltetra(4-benzyl-(1,2,4-triazole))cavitand in the formation of a non-covalent di-cavitand in the future.
Exploring the Effect of Nitrogenated Carbon-Based Electrocatalysts on the Oxygen Reduction Reaction
Aminda D. Cheney-Irgens, Senior Capstone Seminar
The Oxygen Reduction Reaction (ORR) is an important mechanism that occurs at the cathode of metal air batteries and fuel cells, but the kinetics and mechanism of this generally first-order reaction are not well known and sufficient metal-free electrocatalysts don’t currently exist to facilitate the reaction. In order to avoid the use of expensive Pt-based electrocatalysts currently held as the standard, nitrogen-doped electrocatalysts based in Vulcan carbon and carbon nano-onions were studied and the current and current density of the electrocatalysts were compared. Rotating disk electrode (RDE) and rotating ring disk electrode (RRDE) methods were used to analyze the ORR, electrocatalytic behavior, and peroxide intermediate at an electrode rotation velocity of 1600 rpm. Nitrogen-doped carbon nano-onions performed the best of the carbon-based electrocatalysts with a measured current of -0.815 mA and current density of 4.15 mA cm-2. However, this current was at least 1 mA less in absolute value than the measured current of the Pt-doped samples, which indicates more research is needed on metal-free doping strategies.
Concentration Dependence of Bis(trifluoromethane)sulfonimide Lithi-um Salt on Conductivity in a Novel Solid Polymer Electrolyte
Lance Coyer, Senior Capstone Seminar
Solid polymer electrolytes are a promising alternative to the organic liquid electrolytes commonly used in batteries today. By replacing the liquid electrolyte with a solid polymer electrolyte many of the associated safety concerns can be reduced, or eliminated completely. Electrochemical impedance spectroscopy (EIS) was collected using a homemade sample holder capable of temperature control. A novel homopolymer synthesized by ring opening metathesis of oxanorbornene dicarboximide with an oligomeric ethylene oxide (EO) side chain of length 12 (ONDI-12) has previously been shown to have the greatest conductivity at room temperature. The conductivity dependence of poly(ONDI-12) on bis(trifluoromethane)sulfonimide lithium salt (LiTFSI) was consistent over all temperatures observed with a maximum conductivity of 2.2 x10-4 S cm-1 achieved. The glass transition temperature increased proportionally with LiTFSI. The conductivities of the samples were normalized with the respective glass transition temperature, which suggests that [Li+]/[EO] = 0.101 is the optimum ratio.
Synthesizing Coumarins, using Von Pechman Condensation Reaction, as a Fluorescent Reporting Group, for Application in Designing a Novel Thermo-cleavable System of Affinity Chromatography.
Pho Q. Doan, Senior Capstone Seminar
In the presented research work, we have tested the ability for modifying β-keto ester by SN2 alkylation reaction. We tested the Von Pechmann reaction with various homogenous acid and Lewis acid catalysts. We also noticed the difference in the isolation of the 7-hydroxy coumarin and the 7-amino coumarin products and proposed an isolation method for each of the compound and proposed a purification method for purifying 7-amino coumarin compounds.
Absolute Configuration of 5-hydroxy-prostaglandins
Dominic Golding, Senior Capstone Seminar
5-hydroxyprostaglandin E2 and 5-hydroxyprostaglandin D2 are novel prostaglandins which may contribute to pain and inflammation responses in the body. The synthesis of 5-hydroxyprostaglandins was achieved using photosensitized (singlet) oxygenation (1O2) of prostaglandins E2 and D2, followed by reduction of the hydroperoxides to hydroxides using triphenylphosphine, resulting in the formation of diastereomeric products. The diastereomers were isolated using RP-HPLC with unknown configuration, with yields of 3% and 2% for 5S and 5R-hydroxyprostaglandin E2, and 2% and 1% for 5S and 5R-hydroxyprostaglandin D2. Determining the configuration of the eluted 5-hydroxyprostaglandin diastereomers was accomplished after derivatization with (-)menthyl-chloroformate and breaking the 6,7 double bond by ozonolysis, forming 2-hydroxyhexanedioic acid diastereomers. By making 2-hydroxyhexanedioic acid standards from authentic 5S and 5R-HETE, comparison of the 5-hydroxyprostaglandin-derived acid diastereomers and the authentic standards using LC-MS scanning at 357.4 m/z indicated that 5S-hydroxyprostaglandins eluted earlier than the 5R-prostaglandins, with retention times of 2.53 and 2.60 minutes, respectively.
Synthesis and characterization of a single ion conducting solid polymer electrolyte
Hannah R. Hazel, Senior Capstone Seminar
In this study, multiple organic precursor molecules and polymers were synthesized via standard organic reaction mechanisms and ring-opening metathesis polymerization (ROMP) in the ultimate pursuit of a single-ion conducting solid polymer electrolyte. The solid phase nature, high modulus, and single-ion conducting properties of these polymers could help to address some of the safety issues currently associated with lithium-ion battery electrolytes – especially those caused by lithium dendrite growth –
while maintaining effective conductivity levels at room temperature. An oxanorbornene dicarboximide (ONDI) type fused ring molecule was used with a variety of attached side chains as the primary backbone for ROMP. Multiple polymers and copolymers were synthesized with varying ratios of an ONDI monomer with an alkyne side chain for post-polymerization single-ion functionalization via copper catalyzed click chemistry, an ONDI monomer with a long chain poly(ethyleneoxide) side chain, and a norbornene dicarboximide (NDI) monomer with a phenyl group side chain. In this study, the reaction conditions and purification procedures for these organic syntheses and polymerizations were studied for optimization. In the future, these novel ONDI based single-ion conducting polymers synthesized via click chemistry will be characterized to determine their glass transition temperature, dispersity
and molecular weight, transference numbers, morphology, and relative conductivities.
Exploring the mechanisms of intracellular Gram-negative bacteria recognition
Tran T. Hoang, Senior Capstone Seminar
Gram-negative bacteria are notorious for causing infections in the human body. However, the innate immune system can recognize this bacterial presence through the detection of lipopolysaccharide (LPS), an endotoxin that makes up the outer membrane component of gram-negative bacteria. Recognition of LPS allows the detection of the bacteria as a whole, making LPS a potent inflammatory response activator. LPS activates different signaling pathways depending on the location of the bacteria with respect to the host immune cell. Extracellular recognition of LPS is detected by toll-like receptor 4 (TLR4), and the LPS/TLR4 signal transduction pathway has been heavily studied in the past few years. Recent work, however, has also identified the potential of intracellular recognition of LPS, detected by novel receptor Caspase-11. This study tested for the genes that play a role in positively regulating the LPS/Caspase-11 signaling pathway. Out of the selected genes, we have confirmed that SGTA does not positively regulate the pathway, while C8ORF33 showed the most potential in being a positive regulator. The other tested genes, stard8 and CPT1A, required further work to confirm their contribution to the novel pathway.
Designing a Diene to use in a Thermocleavable Linkage for Affinity Chromatography
Alexander R. Holter, Senior Capstone Seminar
A thermocleavable linkage is designed as a method to reversibly bind ligands to stationary-phase media for affinity chromatography. By utilizing a hetero Diels-Alder reaction, ligands functionalized with a dienophile can be bound to a stationary-phase medium functionalized with a diene. To elute an analyte of interest that is bound to the affinity ligand, heat would be used to cleave the Diels-Alder linkage between the ligand and the stationary-phase by a retro-Diels-Alder. The retro-Diels-Alder reaction offers the potential advantages of the recycling and redecoration of the chromatography medium with new affinity ligands. The diene being designed is based on a 9,10-dialkylanthracene scaffold since it does not dimerize readily and acts as a fluorophore. By synthesis of 9-(azidomethyl)-10-methylanthracene, the diene can be attached to an alkyne-labeled chromatographic medium via copper(I)-catalyzed azide-alkyne cycloaddition to form a 1,2,3-triazole linkage. An intermediate diene 9-(bromomethyl)-10-methylanthracene (55% yield) has been synthesized to be attached to the stationary-phase chromatographic medium. To attach the diene, the bromine will be replaced with an azide functional group.
Exploring the Synthesis of Doped Nanorod Quantum Dots Using a Zinc Acetate Precursor
Nicholas J. Jandoc, Senior Capstone Seminar
Nanocrystals can be used in a variety of ways, including inside of luminescent solar concentrators (LSCs) for the use of solar energy. These nanocrystals, which are also called quantum dots, absorb ultraviolet light and emits visible light. Quantum dots were previously synthesized as spheres but new procedures have shown that these quantum dots can also be synthesized as rods, or nanorods, and has the potential to allow for alignment within the LSC to direct the emission of photons in the direction of the concentrator. Current synthetic routes that is used to synthesize these nanorods yields nanorods that are too long and too thin for desired alignment or effective absorbance wavelengths. The goal is to examine how this synthesis proceeds and how to control the aspect ratios of ZnSe/ZnS nanorods by isolating and determining the intermediate species of the reaction and then adjusting the synthetic procedure. The synthesis is done by reacting zinc acetate with oleylamine, dodecanethiol, and selenium powder and then heating the flask to varying temperatures for three minutes. FTIR, NMR, UV-Vis absorption, and GCMS spectra were obtained. ICP-MS analysis was performed to quantify the Zn:Se ratio. “Magic-sized” nanocrystals form at temperatures above 120 °C. Isolation and identification of these intermediates may lead to new insights of nanorod growth.
Evaluation Of a Novel Small Molecule to Improve Gene Editing Out-come
Kenson Jean, Senior Capstone Seminar
Sickle cell disease (SCD) affects about 90,000 people in the US, and millions worldwide, most of them of African, Middle Eastern, or East Indian descent. The average life span of a SCD patient is 30 years less than healthy individuals. Patients in the US have a median life span of 42 or 38 years respectively, for females and males. Gene therapy and editing in hematopoietic stem cells (HSCs) has been used to treat SCD. However, there are a few limitations such as low editing efficiency and decreased cell expansion. Cell expansion is very crucial for gene editing strategies. Our study focused on evaluating a novel small molecule to improve gene editing outcome. The proprietary compound we tested increases HSCs expansion and homology directed repair (HDR) editing efficiency.
Exploring the Synthesis of Doped Nanorod Quantum Dots
Hannah J. Johnson, Senior Capstone Seminar
Nanocrystal quantum dots can be used for a variety of applications. The absorbance spectrum of these nanocrystals can be adjusted by changing their size, which includes both length and width. This research was performed to more fully understand the procedure of synthesizing ZnSe nanorod quantum dots by breaking down the reaction steps and adjusting the precursors and temperatures in the reaction. “Magic-sized” ZnSe nanocrystals appear to be a key intermediate in this reaction and may act as a seed for further propagation of nanorod growth.
Practical Applications of Iron-Catalyzed Wacker-Type Oxidation Reactions
Brian C. Julian, Senior Capstone Seminar
Regiospecific oxidation of alkenes selecting for the markovnikov position is commonly carried out through processes such as oxymercuration – demercuration that use reagents which are harmful for the environment. Here we investigate a possible practical application of a greener oxidation pathway through iron-catalyzed Wacker-Type Oxidation with the intent of making it possible to run on a mass scale for classroom purposes. The presence of the desired product was confirmed through TLC and NMR analysis. Unfortunately, due to COVID-19 lab closure, final purification of the final product was not possible, but NMR analysis confirms that the synthesis of 1,3-Propanediol, 1-phenyl- from cinnamyl alcohol was successful.
Endothermic singlet fission in di-benzoic acid perylene oligomers
Jennica E. Kelm, Senior Capstone Seminar
In a time where there is an increasing need to develop sustainable energy sources, dye-sensitized solar cells (DSSCs) are a promising alternative because they are a relatively inexpensive, composed of abundant materials and environmentally friendly. Conventional dyes used in DSSCs produce one electron‑hole pair per absorbed photon, wasting excess photon energy as heat; however, dyes undergoing singlet fission could in theory produce two electron-hole pairs per absorbed photon. Singlet fission (SF) is a spin-allowed process by which a molecule in its excited singlet state shares its energy with a ground state molecule to produce two triplet-excited molecules creating the potential of doubling the photocurrent from high-energy photons in solar cells. A series of perylene‑based compounds capable of intramolecular singlet fission have been developed at NREL and in this work we derivatize the aforementioned oligomers with carboxylic acid groups to enable their application in DSSCs. Specifically, synthetic and purification methods were developed for a di-carboxylic acid mono-perylene chromophore. We characterized the optical properties of the monomer in solution, which reveal a broader, and more blue‑shifted absorption spectrum compared to the monomer without carboxylic acids, while fluorescence spectra exhibit more similarity between the two compounds. Time-resolved photoluminescence results reveal that most of the fluorescence from the singlet state is quenched when the compounds are ligated to TiO2, however, a faint, broad and red‑shifted emission indicates the presence of a small number of electronic-trap sites. Transient absorption results indicate the growth of a triplet state and a decline of the singlet state, indicating that singlet fission is happening. More analysis is needed to confirm whether the electron injection from the perylene to the TiO2 is taking place, and whether it occurs from the singlet or triplet state. The triplet excitons that are formed on picosecond timescale decay slowly, which is ideal for harnessing them in photovoltaic devices.
Sweet Taste and Safety: Health and Environmental Effects of Aspartame and Sucralose
Leighton R. Kingma, Senior Capstone Seminar
The use of artificial and non-nutritive sweeteners has been on the rise in the past several decades. The increased intake of these sweeteners has led to many studies that seek to determine what potential adverse effects these sweeteners have on people and the environment. This review serves to report on several health effects that are associated with the intake of two popular artificial sweeteners: aspartame and sucralose. Potential negative effects associated with aspartame included weight gain, cancer risk, effect on dental caries, and neurological effects. Sucralose was potentially associated with weight gain, cancer, diabetes, and is an environmental contaminant. Aspartame was found to cause weight gain. Links between cancer and aspartame consumption require additional research. Aspartame was found to have a preventative effect on dental cavity formation. Negative neurological effects were also reported in literature. Sucralose use was found to cause weight gain, and type 2 diabetes risk was found to increase with its use. Cancer risk as a result of sucralose consumption requires additional research. Sucralose is an emerging environmental contaminant that could have largely negative implications in the future.
A study on the efficacy of S. Cerevisiae-derived alcohol dehydrogenase under oxidative stress
Anh-Duong T. Le, Senior Capstone Seminar
The use of oxidative stressors in viticulture is widespread and has practical applications to help cessate fermentation. The purpose of this research is to determine the effect of oxidative stress on alcohol dehydrogenase (ADH) by measuring the rate of NAD+ formation using spectrophotometric assays. Hydrogen peroxide was used as the oxidative stressor, and was applied with incubation for one hour. In short, it was found the rate of NAD+ reduction was drastically decreased in ADH containing lysates when oxidized during education to 8.6% of the original velocity in the first sample, and to 26% in the second sample.
The Shikimate Pathway
Brianna K. Lindsey, Senior Capstone Seminar
The shikimate pathway is a biosynthetic pathway for the synthesis of chorismate, the precursor the aromatic amino acids phenylalanine, tryptophan and tyrosine as well as other secondary metabolites. The process is only seen to occur in microorganisms and plants, making it a great target pathway for inducing toxicity into unwanted plants. Glyphosate for example is
one of the most widely used herbicide worldwide, specifically targeting and inhibiting the enzyme 5-enolpyruvylshikimate 3-phosphate (EPSP) synthase. Due to humans and animals not containing the shikimate pathway, it is necessary for them to ingest all of their required aromatic amino acids. Shikimate acid is one of the intermediates in the pathway, which has been very
important in the synthesis of the flu medication, Tamiflu.
Sensitive electrochemical detection of PFOA using redox active nickel Prussian blue capture probes
Thomas J. Mallos, Senior Capstone Seminar
Per- and polyfluorinated alkyl substances (PFAS) are persistent organic pollutants linked to a variety of health risks, such as cancer, miscarriage, and liver damage. Current ex situ detection methods for PFAS are expensive and time consuming, leading to the need for efficient, sensitive, and selective in situ methods. Metal organic frameworks (MOFs) and similar porous networks are known to adsorb PFAS, with some having sensing capabilities. We are looking at electrochemical affinity sensors, with preferential PFAS selectivity. Nickel Prussian blue (NiFe), a hexacyanoferrate framework with intrinsic redox activity, has previously been used as an electrochemical sensor. This
work focuses on the capture and sensing of perfluorooctanoic acid (PFOA), one of the dominant PFAS, using NiFe. PFOA capture and detection leads to direct changes in the Fe(CN)6 3 – /4 – redox couple which is a structural unit of NiFe, and can be monitored directly through cyclic voltammetry. PFOA was detected at 10 ng/L concentrations, well below the EPA health advisory limit. Results here suggest NiFe could be used to detect other PFAS, like perfluorobutanoic acid (PFBA) or perfluorooctane sulfonate (PFOS), but further work is necessary to understand the adsorption mechanism.
Bioaccessability of Lead on the Hillsides of the Bunker Hill Su-perfund Site (Smelterville, ID)
Nicole M. Martin, Senior Capstone Seminar
The hillsides in the Bunker Hill superfund site are contaminated with lead from over a century of mining and some of that is in a form the human body can absorb leading to long term damage. The Bunker Hill Superfund site is 1,500 sq. miles of public and private land located in Smelterville, Idaho that affected by the Bunker Hill Metallurgical Complex (mine and smelter) which was operation from 1917 until 1981. Over 7,000 properties have had soil remediation and the hillsides have been subject to numerous revegetation and site stabilization efforts. This project focused on testing samples from the hillsides that were previous examined 25 yrs ago to see where the current lead concentrations are and how much of that lead if bioaccessible using an in vitro method followed by analysis by laser induced breakdown spectroscopy (LIBS) and inductively coupled plasma mass spectroscopy (ICP-MS). The analysis provided evidence that some areas on the hillsides are still heavily contaminated with 78% of samples being above 3,000 ppm, 25% above 40,000 ppm, and a maximum concentration of 89,000 ppm. The bioaccessibility was 130 ± 20% and was calculated using the LIBS results for total soil lead concentration.
Adaptive Mutation from induced DNA damage of yeast 8- oxoguanine glycosylase cells
Zohal G. Mohammady, Senior Capstone Seminar
The OGG1 gene plays a role in DNA damage repair of guanine and affects the prevalence of mutations in cells in response to oxidative stress. This study looks into the differences between adaptive and replicative mutagenesis induced by oxidative DNA damage in order to determine underlying mechanisms that may have taken place. In Saccharomyces cerevisiae, the occurrence of adaptive mutants after induced DNA damage in wild-type (WT) cells increased by 6.52-fold and in ogg1 cells by 1.33-fold. The replicative mutants also increased after induced DNA damage, 2.79-fold in WT cells and 1.71-fold in ogg1. The smaller fold increase in replicative mutants in the WT strain indicate mechanisms of DNA repair with more time to grow after oxidative exposure whereas the ogg1 strain had a considerable higher number of mutants in comparison with its lack of repair. With these results, we can determine the mechanisms of adaptive mutagenesis that occur in a cell.
Investigating the Order-to-Disorder Transition Phase Behaviors of Asymmetric Core-Shell Bottlebrush Polymers
Emily M. Ness, Senior Capstone Seminar
Block polymers, which include two or more chemically different segments, are of substantial technological interest due to their ability to self-assemble into various microphase separated morphologies with tunable microdomain sizes. Diblock and triblock copolymers are of particular interest in nanolithography for the manufacture of advanced microelectronics, due to their potential to access sub-14-nm feature sizes required for the development of faster and more efficient microprocessors. In this project, we investigate how nonlinear block polymer architectures impact the thermodynamics underlying their microphase separation. Specifically, we describe the synthesis of densely grafted, core-shell bottlebrush polymers derived from linking cylinder-forming ABA-type triblocks through their chain midpoints. Using temperature-dependent synchrotron small-angle X-ray scattering, we demonstrate that the order-to-disorder transition temperatures (TODT) of these bottlebrushes increase on increasing the bottlebrush backbone length. These results are interpreted in terms of the configurational entropy penalty for ordering a disordered triblock polymer melt.
Screening for Arsenic, Copper, Lead, and Cadmium Contamina-tion in Soil at Point Defiance Elementary School, Ruston, WA
Victoria T. Nguyenle, Senior Capstone Seminar
Various heavy metals that were emitted from the ASARCO Smelter (As, Cd, Cu and Pb) are present in soil around the Puget Sound area. This study measured the concentration of heavy metals in the soil at Point Defiance Elementary school to determine if the school would require a soil clean up. Soil samples were gathered on the outer fields of the school at 24 different sites and then heavy metal concentrations were detected via Laser Induced Breakdown Spectroscopy (LIBS) and ICP-MS. The results revealed that the highest concentration of As, Cd, Cu and Pb, measured by ICP-MS, were 4.72 ppm, 0.198 ppm, 800 ppm and 58.0 ppm respectively. Analysis via LIBS revealed that the highest concentrations of Cd and Cu were 42.6 ppm and 2560 ppm and that concentrations of As and Pb were below the detection level at the sites comparable to ICP-MS. These results demonstrated that the concentrations of these heavy metals as determined by ICP-MS were lower than the EPA Standard Cleanup level, indicating that further cleanup was not required. In comparing the analytical techniques of LIBS and ICP-MS, the concentrations of the metals were too low to determine if LIBS was a sufficient screen tool. Further investigation would involve the use of higher concentrated heavy metals.
Quantum Dot Ligand Exchange for Luminescent Solar Concentrators
Megan M. Packer, Senior Capstone Seminar
Luminescent solar concentrators (LSCs) can be used to collect solar energy due to the semiconductor nanocrystal quantum dots that absorb the sunlight and emit photons. The outermost shell of quantum dots is composed of organic ligands that impact the stability, solubility, and luminescence of the quantum dot. The goal of the research was to develop ligand exchange protocols and characterize the quantum dots that have been exchanged with new ligands. The ligands that are on the quantum dots during synthesis can be exchanged with ligands that will improve the quantum dot stability, luminescence, and ability to remain well mixed in the LSCs. Two ligands, 6-azidohexanoic acid and 12-azidododeconoic clicked with a methacrylate monomer were exchanged with Mn:ZnSe/ZnS and CdSe/ZnS quantum dots.
Diversity in Chemistry Education in High School and College
Betsabe A. Parmly, Senior Capstone Seminar
Ensuring that everyone is equally welcome in the chemistry discipline begins with educators. Previous literature has shown that utilizing certain teaching methods in chemistry classrooms can improve scores, motivation, and retention for all students, especially students from underrepresented groups. Active learning strategies, the flipped classroom model, and cohort learning models are all examined for their potential in improving student success rates and increasing diversity in chemistry. A survey was also conducted at PLU to answer the following questions: 1. Do positive high school chemistry class experiences correlate to future interest in chemistry and STEM fields? 2. If so, what teaching strategies increase students’ enjoyment and success in chemistry classes? 3. Are there key differences in responses between men and women or majority or minority ethnic groups? The survey results showed that positive experiences in the high school classroom did not correlate with student decisions to major in chemistry or take further chemistry courses in college. The survey also showed that students’ perceptions of their chemistry course, positive or negative, were greatly influenced by their teachers and fellow classmates. The results also did not indicate that there were any differences in responses between men and women. They also showed that students of diverse ethnicities were more likely to enjoy their chemistry class than Caucasian students. These results seem to suggest that chemistry classrooms are more inclusive now than they have been in the past.
An Analysis of Chemicals in Tampons via SPME/GCMS and ICPMS
Sophie M. Schroeder, Senior Capstone Seminar
ABSTRACT: Tampons are one of the most widely used feminine hygiene products and are highly regulated by the Food and Drug Administration. Despite this, there is not much analytical research available concerning chemicals that are bioavailable within tampons. To address this, we used SPME/GCMS and ICPMS to establish a basic view of chemicals present in three brands of regular-sized tampons: Playtex, a scented option; Kroger, the cheapest available; and Natracare, an organic brand. Playtex scented tampons had 22 different chemicals present, many of which were various perfumes. The three most prevalent across the four SPME fibers were galaxolide, tonalide, and sodium tetrahydrojasmonate. Galaxolide was quantified using a standard and found to be present in concentrations of 0.92 ppm. The metal ion concentrations above 10 ppb were zinc at 22 ppb, chromium at 12 ppb, and vanadium at 11 ppb. No metals ions were hazardous at the concentrations recorded. The Kroger tampons had four chemicals present according to the GCMS data, but in low amounts. The highest metal ion concentration was zinc at 43 ppb. Antimony was present at 2 ppb, a potentially concerning concentration. No other metals ions were hazardous at the concentrations recorded. The Natracare tampons had ten chemicals present in the SPME/GCMS data. The two most significant of these were 2,4-Di-tert-butylphenol and 1-Oxaspiro[4.5]deca-6,9-diene-2,8-dione, 7,9-bis(1,1-dimethylethyl)-, both of which are chemicals commonly used in plastic refining and manufacturing; a possible source of introduction to the tampon for these is the recycled plastic wrapper. The ICPMS showed iron to be present at a concentration of 20 ppb. No other metals ions were hazardous at the concentrations recorded.
MARTX’s role in varied immune response from infection by closely related Vibrio vulnificus.
Kyle M. Siemers, Senior Capstone Seminar
Vibrio vulnificus is a water-dwelling bacteria that, through the multifunctional autoprocessing repeats-in-toxin (MARTX) toxin, infects people through skin lesions or by ingestion to cause serious disease and even death. The MARTX toxin im-pacts its host cell’s integrity and ability to mount an immune response by the actions of its effector domains. Different strains and toxin organization “types” have shown to have variable affects enacting an immune response to clear the bacte-ria. In this study, the immune response of infected cells is modelled by measuring the amount of IL-8, a proinflammatory cytokine, secreted by the intoxicated cell. Based on which strain of bacteria and consequently, which toxin organization type it contained, the differences between types and genetic relatedness of the bacteria strains were investigated. We found that out of the five toxin types studied, four types suppressed the host cell’s ability to enact an immune response. Observed differences in immune response suppression between toxin types that varied by only by one effector domain shows that the combination of domains that make up the MARTX toxin can result in altered immune response from the individual effector domain. Further, we saw differences in immune response suppression among different strains with the same toxin type, which discouraged the reliance on solely the toxin type to precisely predict immune response in the system we modelled with IL-8.
Post Synthesis Heat Treatment of Doped Magnesium Zinc Selenide Nanocrystals
Erik R. Straume, Senior Capstone Seminar
Zinc selenide nanorods doped with manganese were synthesized. These rods were put under post synthesis heat treatment in order to study the effects of heating in different ligands. Studies have been done by other groups has shown an effect when heating nanorods in amines. Heat annealing was done but the effects are unable to be studied due to the large size dispersity of the rods before synthesis.
How low can you go: Detecting dopamine on ruthenia modified pyrolytic carbon electrodes.
Chelsea N. Swank, Senior Capstone Seminar
The electroanalysis capacity of both pyrolytic carbon nanomaterials and nanocrystalline ruthenia dioxide in its rutile form has been studied in concentrations of dopamine from 1 nM to 10 mM in 1.0 M perchloric acid using cyclic voltammetry and differential pulse voltammetry. Ruthenia-dioxide modified pyrolytic-carbon electrodes demonstrated a stronger sensitivity and a
lower limit of detection for sensing dopamine than the carbon modified electrodes using differential pulse voltammetry respectively: 9.4 (± 0.2) ⨉ 105 μA·M-1 and 5 (± 6) ⨉ 10-8 M; 1.71 (± 0.03) ⨉ 106 μA·M-1 and 6.4 (± 9) ⨉ 10-7 M. Using cyclic voltammetry, the ruthenia-modified electrodes lacked dopamine oxidation peaks in lower concentrations of dopamine: 1 nM – 10 μM, which is thought to be caused by the preference of charge storage, due to the amount of pseudocapacitive response, rather than transfer during oxidation. Furthermore, the ruthenia-modified electrodes corroded with continued use in 1.0 M perchloric acid. Although the results of the UV spectra are conflicting with our primary focus, this technique exists as a guide for exploring biological buffers with use of Ruthenia modified electrodes in its nanocrystalline form for the detection of dopamine and other reactive biological ions and mole-cules.
Analysis of catalyst contamination in polyethylene terephthalate (PET) plastic water bottles
Ludmila S. Volosevych, Senior Capstone Seminar
Eleven different brands of PET bottled water were collected from the Washington State super markets and analyzed to quantitatively determine antimony and titanium concentrations in the bottled water. Analysis was conducted using a Perkin Elmer NexIon 350X ICP-MS. ICP-MS TotalQuant mode was also used to conduct a qualitative analysis for over 100 elements, including germanium. A rhenium internal standard was used to monitor method precision and to normalize analyte concentrations. Antimony and titanium were calibrated on a 10-point calibration with R2 values of 0.99990 and 0.99987, respectively. Antimony concentrations varied between 0.027 0.009 ppb and 0.69 0.04 ppb. Titanium concentrations varied between 0.60 0.06 ppb and 6.7 0.4 ppb. The qualitative analysis revealed that germanium was present in PET water samples at concentrations as high as 0.2 ppb. All antimony concentrations determined were below the US EPA maximum contamination limit of 6 ppb. There are no current drinking water contamination limits for titanium or germanium.
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