Western Kentucky University
Department of Physics and Astronomy

Colloquium

WKU Physics Majors

Department of Physics and Astronomy
Western Kentucky University

"Senior project presentations"

November 27, 2017 @ 4:00 pm in TCCW 201

Abstract

Zachary Thomas
"Photodeactivation of pathogenic bacteria using methylene blue and graphene quantum dot"

A biocompatible photodynamic therapy agent that generates a high amount of singlet oxygen with high water dispersibility and excellent photostability is desirable. In this work, a graphene-based biomaterial which is a promising alternative to a standard photosensitizers was produced and its efficiency compared to a standard photosensitizer, methylene blue. Graphene quantum dots (GQDs) were synthesized by irradiating benzene and nickel oxide mixture using nanosecond laser pulses. High-resolution transmission electron microscopy (HR-TEM) results show GQDs whose size less than 5 nm with very good water dispersibility were successfully obtained. UV-Vis spectra and photoluminescence spectra shows that GQDs have an absorption peak around 270 nm and maximum emission at 430 nm with the excitation wavelength of 310 nm. Deactivation of Escherichia coli (E. coli) a gram-negative bacterium with methylene blue and carbon nanoparticles was studied by irradiating with different wavelengths. The results show a significant decrease in the number of colony forming units of E. coli. Our results show that GQDs can potentially be used to develop therapies for the eradication of pathogens in open wounds, burns, or skin cancers..

Devon Loomis
"Comparison of Metal Oxide Semiconductor Response to Bacterial Growth on Spoiled Meats"

The SGX MiCS-6184 metal oxide semiconducting sensor array was used to measure the off-gassing of meat samples during their spoiling process. This signal response was then compared to the count of colony forming units on the meat. The cfu’s were found by diluting quantities of the meat in DI water and incubating them for a span of 48 hours on agar plates. The relationship between the signal response and bacterial count suggests that the SGX sensors are a reliable method for indicating the level of spoilage of certain meats. I will discuss the mathematical methods we used and how they suggest a connection between the two data sets.

Seth Harper
"Detecting Spoiled Meat using Novel Metal Oxide Sensors"

Having the ability to tell if food is spoiled has always been a touch-and-go concept at best. The manufacturer posts a “best by” date and past that the only way to tell is by smell. So, what if it was possible to use an electronic nose to smell the meat and tell if it is spoiled or not? That is the purpose of this experiment. Using the sensor array SGX MiCS-6814, which is an array of 3 separate metal oxide sensors that detect when different gases are nearby. When a sensor is turned on the surface begins to heat up, which causes electrons to leave the surface. This causes the sensors to be highly reactive. When a gas that fits the specific type of sensor is near the surface, it will oxidize the surface of the sensor which will cause a change in resistance. This change in resistance creates the signal that is measured. The primary focus of this experiment is to take various stages of spoiled meat and record a sensor response for these stages. This response will then be compared to biological colony counts. This will provide some proof that the sensor shows that the meat is spoiled. The task was to find a calibration curve for the sensor array. Meat was purchased from the market and the purchase date and expiration date were recorded. The meat was stored in a lab refrigerator at 4o C. Measurements were taken daily to see how the response varied as the meat became more spoiled. Every time a sensor measurement was taken, bacteria was cultured on agar plates from the same sample. The bacteria cultures were incubated for 48 hours to allow growth to occur. The colony counts were compared to the sensor measurements.

James Pierce
"Beta Testing the QES1."

Quantum optics, though a relatively new field in physics, has already revealed many applications for the present and the future. However, there exists a problem: not many people possess the foundational knowledge and experience needed to continue the research in this field. Qubitekk, a leading company in quantum physics, has been developing an instructional quantum optics lab kit for the very purpose of supplying crucial background information. This presentation will touch on the various applications of quantum optics and discuss the ongoing beta-testing of the QES1 Quantum Optics Lab Kit.