Physical Sciences and Mathematics Commons^™

Multiscale Variability Of Heavy Metals In A Western U.S. Snowpack, Kelsey Hefner

Student Research Symposium

Natural and anthropogenically sourced particulates are deposited from the atmosphere to landscapes via dry and wet deposition, making frozen winter snowpack a natural archive of atmospheric elemental composition. Wildfires in the Western United States are increasing in extent, duration, and severity, especially in alpine regions. Severe fires remove forest canopy and can impact how atmospheric elements are dispersed and stored across snow-dominated watersheds. We evaluated Al, V, Cr, Mn, Ni, Cu, As, Zn, Se, Mo, Cd, and Pb concentrations in 394 winter snow core samples. We collected samples in 2019 and 2020 from a chronosequence of eight forests that burned …

Photocathodes From Aerobic Oxidation Of Tellurorhodamines, Amelia Jellison

Student Research Symposium

Contemporary dye-sensitized solar cells are far less efficient than silicon solar panels, therefore this project seeks to develop an improved dye sensitized photocathode. Tellurorhodamine dyes, including mesityl derivatives and tellurium black, have been chosen to increase efficiency through increased light harvesting. The photophysical and electrochemical properties of tellurorhodamines with varying structures are analyzed to quantify its efficiency to serve as a dye sensitized photo cathode. Dyes undergo aerobic oxidation facilitated by light, the absorption profile is obtained before and after. Mesityl derivatives are known to experience significant red-shifting following aerobic oxidation. At its base oxidation state, tellurium black experiences an …

Comparison Of Heavy Metals In Spinach Grown On The Roof Ground Location At Portland State University, Tyler A. Robin

Student Research Symposium

As a result of urbanization, fresh, healthy food can be expensive and easily contaminated but space for local farming is limited. Roofs can be underutilized in densely populated cities and can offer a space for local fresh farming. The purpose of this study is to continue a previous study done in 2021, to find if growing leafy vegetables on the roof can limit heavy metal exposure from air pollutants. This study compares spinach grown on the roof in 2021, 2019 and spinach bought from stores around the Portland State University campus and the heavy metals found in these greens. The …

Simple Arenes As Aryne Synthetic Equivalents Via Sulfonium Salt Intermediates, Riley A. Roberts

Student Research Symposium

Arynes are ephemeral molecules that are yet to be fully exploited in synthetic strategy because they are often challenging to access. These reactive intermediates participate in a myriad of reactions that conventional chemistry is incapable of, making them extremely useful for the synthesis of important molecules like pharmaceuticals and agrochemicals. While classical approaches for synthesizing arynes employ cheap starting material, extremely harsh reagents are necessary to generate the aryne. In contrast, methods that do not require harsh reaction conditions do require starting material that is exceedingly difficult to synthesize. To access arynes quickly and efficiently, the work described herein aims …

Computational Investigation Of The Mechanism Of An Octahedral Ni(Ii) Proton Reduction Catalyst And Importance Of Intramolecular Hydrogen Bonding, Avik Bhattacharjee, Dayalis S.V. Brown, Carolyn N. Virca, Trent E. Ethridge, Oreana Mendez Galue, Uyen T. Pham, Theresa M. Mccormick

Student Research Symposium

Water-splitting to make hydrogen gas is of extreme importance in the field of alternative energy research. Transition-metal complexes are capable of catalyzing the conversion of water to hydrogen at higher pH, with low overpotential. Our research focuses on the importance of intramolecular hydrogen bonding (H-bonding) on the pKa and thermodynamic stability of the catalytic intermediates of a well-known proton-reduction catalyst, nickel (II) tris-pyridinethiolate. Density Functional Theory (DFT) calculations on the parent catalyst and eleven derivatives demonstrate geometric isomer formation after the protonation step of catalysis. These isomers differ in the relative thermodynamic stabilities and pKa values, which can be attributed …

Metallodithiolate Ligands For Reversing Metal Ion Induced Aggregation Of Beta Amyloid, Eleanor K. Adams, Marilyn Rampersad Mackiewicz

Student Research Symposium

Alzheimer’s Disease (AD) is the sixth leading cause of death in the United States with no known methods to cure, reverse or halt disease progression. The “metal hypothesis” states that Fe^II, Cu^II, Zn^II, and Al^II bind to truncated Aβ peptides and form soluble oligomers which deposit as senile plaques. These plaques play a crucial role in AD pathogenesis. For example, metallated-Aβ aggregates are hypothesized to disrupt membranes or generate a reactive oxygen species (ROS) through redox cycling in the presence of Cu^I/II or Fe^III/II and a reducing agent. ROS can lead …

Diagnostic Platform For Current Health Status Monitoring, Albert S. Benight, Megan M. Koslen, Matthew W. Eskew

Student Research Symposium

Our approach is based on physical measurements of blood plasma and exploits the plethora of information contained in the human plasma proteome, as a reporter of human health status. The assay involves collection and analysis ofthermograms of plasma from human blood measured by differential scanning calorimetry (DSC).

Plasma thermograms arise from the temperature-induced denaturation profile of proteins within blood plasma measured by DSC. This insightful measurement thereby provides a snapshot of the current state of the human plasma proteome which directly informs on overall systemic health. Such measurements have been shown to be highly accurate and sensitive indicators of health …

Thiophene Based Molecular Sensors Towards Mercury Detection, Austin K. Shigemoto, Carolyn N. Virca, Sam Underwood, Lauren Shetterly, Theresa M. Mccormick

Student Research Symposium

Toxic heavy metals such as mercury have increased in concentration in the environment due to pollution. Inorganic mercury in the environment can be later converted to a more toxic form: methylmercury. Regular consumption of fish containing methylmercury can lead to several cognitive and motor disorders as well as Minamata disease. The current methods used to detect both methylmercury and inorganic mercury in sea life and drinking water involve long sample preparation and cost. In order to more efficiently track this toxic metal in the environment and identify contaminated food and water sources, a cheaper and faster method of detection is …

Training An Asymmetric Signal Perceptron In An Artificial Chemistry, Peter Banda

Student Research Symposium

Autonomous learning implemented purely by means of a synthetic chemical system has not been previously realized. Learning promotes reusability, and minimizes the system design to simple input-output specification. In this poster, I present a simulated chemical system, the first full-featured implementation of a perceptron in an artificial (simulated) chemistry, which can successfully learn all 14 linearly separable logic functions. A perceptron is the simplest system capable of learning inspired by the functioning of a biological neuron. My newest model called the asymmetric signal perceptron (ASP) is, as opposed to its predecessors such as the weight-race perceptron (WRP), substantially simpler by …

An Alternative Ribozyme For The Rna Hypercycle, Ishak Elkhal

Student Research Symposium

In the quest to forward understanding of the prebiotic world (specifically, the RNA World Hypothesis), one of the most interesting paradigms to consider is the potential for cooperative networks that may have driven molecular evolution forward. Such a network may exist as an RNA hypercycle, as proposed by Eigen (1977). Much progress has been made towards an RNA hypercycle-like system, especially using the Azoarcus ribozyme system demonstrated by Vaidya et al. (2012). The current work is dedicated to constructing a second model as a cooperative RNA network, utilizing a group I intron from Coxiella burnetii (Cbu1917). The intron was constructed …