posters
EFFICIENCY OF IDEAL AND NON-IDEAL HEAT ENGINES
Ethan Mickelson Taylor Nelson Dr. Marie Lopez Del Puerto
University of St. Thomas - St. Paul
In this project we studied computational models for ideal and non-ideal Carnot heat engines with a focus on understanding their efficiencies. A Carnot engine consist of a cycle with two isothermal and two adiabatic stages that yield the theoretically highest efficiency. We wrote a simple MATLAB simulation for an ideal Carnot engine as described in Arnaud and Chusseau (AJP 78 (1): 106-110). We then modified our code to simulate a non-ideal engine using ideas from Johansson (Journal of Thermodynamics (2014), 217187). These models allow us to gain a better understanding of the second law of thermodynamics and can be used as the basis of a project for a thermodynamics course.
ELLIPSOMETRIC DETERMINEATION OF THIN-FILM THICKNESS & COMPLEX REFLECTIVE INDEX
Yousef Almujaly Dr. Adam Green
University of St. Thomas - St. Paul
Over the past few months, we found that ellipsometry is a reliable tool in determining the thickness of thin film coatings. Our measured values for semiconductor reference samples and glass slides coated with gold or carbon are very close to known thicknesses. Our next step is to determine the complex refractive index of these samples. In the future, we will use ellipsometry to quantify optical properties of butterfly wings, scarab beetle shells, and other biological thin films.
ENVIRONMENTAL AND CHEMICAL APPLICATIONS OF POLARIZED MICROSCOPY TO VISUALIZE MICROPLASTIC CONTAMINATION
Alexa Chelsey Dr. Adam Green
University of St. Thomas - St. Paul
Polarized microscopy is widely employed to characterize optically anisotropic materials, with interference colors arising from birefringence serving as a convenient means to visually differentiate materials. While crystalline materials typically exhibit birefringence, amorphous materials can also demonstrate this property when subjected to strain, as is the case with many microplastics. These particles, ranging from 125 μm to 5 mm in size, are either constructed or broken down from larger plastics. These particles are pervasive throughout the environment and have been of recent concern due to their negative effects on human and environmental health. This project aimed toward providing an accessible method for undergraduate students to visualize the pervasiveness of microplastics. Through imaging of microplastics and other birefringent materials such as common crystals (e.g. vitamin C, urea, and caffeine), students were familiarized with polarization properties of materials. A chemistry focused approach to the physics was taken to show the interdisciplinary nature of this project.
EVALUATING THE EDUCATIONAL EFFECTIVENESS OF A FOUNDATIONS OF MODERN PHYSICS LAB COURSE
Jennifer Graham Dr. Rob Davies
University of St. Thomas - St. Paul
The physics department at the University of St. Thomas teaches the course Foundations of Modern Physics with the aim of connecting ideas behind particle and nuclear physics to the evolution of the universe after the Big Bang and the four fundamental forces of nature. Along with the lecture is the laboratory component, the current rendition of this course includes three labs focused on techniques of particle detection covering the topics: 1/r2, beta spectroscopy, and anti-matter matter annihilation. One of us (Jennifer) took this course in the Fall of 2024 while the other (Rob) taught the laboratory portion of the class. As a student of Physics Education Jennifer is in an unusually good position to critique the course content. The goal of our work together has been to improve the Physics 215 laboratory content by leveraging Jennifer's experience in the course and by expanding our view of the possibilities by reviewing other available curricula that covers similar topics. After reviewing TBD other curricula covering nuclear physics laboratory and reflecting on our experiences with the existing curricula, we identified three areas of current course content for improvement: the relationship between a Geiger-Muller tube and high voltage, counting statistics, and how students discover deadtime. Over the past four months, we have drafted three activities for inclusion in next fall's course. These different activities focus on building the foundational understandings necessary for the student-based learning and higher-order thinking completed throughout the semester. By incorporating these activities, it is our objective that students can use the tools to analyze data and mathematically model physical ideas with a better understanding of the experimental conditions and theory that is taught through the course's three labs.
INVESTIGATING ECONOMIC MEHTODS TO SYNTHESIZE WOOD BIOCHAR FOR SUPERCAPACITOR ELECTRODES
Josh Sedarski Anders Anthonisen-Brown Dr. Lifeng Dong
Hamline University
2024 POSTER CONTEST 1st PLACE WINNER
We investigated economic methods for producing bur oak biochar to replace fossil fuel-derived activated carbons as electrode materials for supercapacitors. Three synthesis methods were evaluated by their operating temperatures, mass yield, setup cost, ease of use, and their performance in supercapacitor electrodes: a top-lit updraft gasifier, distillation of wood, and a biochar kiln. The resultant biochars were fashioned into electrodes of coin-type supercapacitors and tested for their specific capacitance, cycling stability, and electrical conductivity. The gasifier demonstrated the best electrode material, with a median specific capacitance of 70.14 F/g, cycling stability of 97.37% after 250 cycles, and an internal resistance drop of 55.8 Ω (all tested at a 0.5 mA charging current). This is close to commercially available carbons (83.55 F/g, 98.99%, 93.0 Ω), and outperforms the kiln (40.79 F/g, 123.03%, 239.8 Ω) and distillation methods (20.57 F/g, 97.72%, 112.2 Ω). The gasifier also possessed high operating temperatures (>550℃), low setup costs (~$50), a mass yield of 18.84%, and user-friendly operation. Future work will optimize composition of the gasifier biochar, explore different wood species, and search for more sustainable chemical activation agents.
MULTISPECTRAL IMAGING FOR ART, MEDICINE AND THE ENVIRONMENT
Laney Tomaro Dr. Adam Green
University of St. Thomas - St. Paul
Light of different wavelengths penetrates materials to different depths and can reveal important information about structural layers. In many cases, infrared light can be used to image deep structures while blue and green light display features closer to surfaces. Dermatologists sometimes use this effect to diagnose skin lesions, museum curators utilize it to peer below paint layers to visualize charcoal underdrawings, and environmental scientists apply it to various substrates, underneath the surface of water, as well as to soil and crop imaging. This poster is a progress report showing simple, inexpensive ways to perform multispectral imaging in the undergraduate laboratory. We are just beginning this project, but preliminary results look promising. Using either color cameras or monochrome cameras in conjunction with color filters, we have found that subtraction of images at different wavelengths can enhance the contrast of targets in turbid media, providing valuable insight and information about the material and its composition.