Browsing by Author "Le, An-Phong"
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Item The Design and Construction of an Affordable Raman Spectrometer(Florida Southern College, 2022-05) Baxmann, Alivia; Le, An-PhongRaman spectroscopy is capable of identifying unknown substances in a fast and nondestructive manner and has found a wide range of uses, such as identifying hydrogen peroxidebased explosives, characterizing chocolate, and verifying gemstone identity. Commercial Raman spectrometers can easily cost tens of thousands of dollars and building a low cost version would enable more widespread adoption of this technique and make additional analytical applications feasible. Undergrad chemistry courses leave out how an instrument works in favor of teaching how to interpret the results unless special topics classes are offered. In industry, chemists are expected to do general maintenance and troubleshooting on all instruments present in the lab. Giving students the opportunity to handle equipment prior to a business setting allows for increased confidence. The basic parts have been assembled with the aid of a 3D printer. Preliminary results will be discussed as well as possible future uses of the project.Item Functional nanoimprinted plasmonic crystals for chemical sensing and imaging(Springer, 2012) Le, An-Phong; Gray, Stephen K.; Nuzzo, Ralph G.; Rogers, John A.We describe here nanoimprinted plasmonic crystals composed of highly uniform subwavelength metal nanohole and nanopost arrays and their application in surface-enhanced sensing and imaging. Soft nanoimprint lithography is a versatile, cost-effective method to precisely replicate these structures with well-characterized optical properties. These plasmonic crystals support multiple surface plasmon modes controlled by the design rules of the nanostructures, allowing us to optimize the devices for operation in a particular wavelength range. We have demonstrated the ability to spectroscopically measure bulk refractive index changes and mechanical deformation of hydrogels resulting from pH changes, thin film imaging with sensitivities down to submonolayer levels using a common optical microscope, and Raman signal enhancement using a single common device framework. These plasmonic crystals have the potential to overcome many of the technological limitations that have limited the widespread application and integration of surface-enhanced analytical techniques.Item Quantifying the “Golden Ratio” of Hyper-Palatable Foods: What Makes Junk Food So Addictive?(Florida Southern College, 2022-05) Schabes, Madeleine; Le, An-PhongThe rising popularity of hyper-palatable foods is motivating research on what makes a food addictive. The current research focuses on neurological and psychological explanations, not on the foods’ physical makeup. It is suggested that food companies strategize the ratio of salts, sugars, and fats to overcome a person’s natural eating regulation, or sensory-specific satiety (SSS.) This strategy is referred to as the “golden ratio” or “bliss point” but has never been quantified. The study will compare popular and unpopular potato chips as determined by purchasing trends and rankings. For this investigation, the salt, sugar, and fat content was measured through analyzing chloride, dextrose, sucrose, fructose, lactose, and solid fat content. Subsequent statistical analyses will find if different ratios exist between popular and unpopular potato chips. If a common ratio is found, it could aid in ingredient reduction without affecting palatability. This can be a major cost-saving measure for the food industry, and it could make foods healthier for people with conditions such as diabetes and hypertension.Item The Use of Simulations with Active Learning Exercises(American Chemical Society, 2022-01-31) Harvey, David T.; Le, An-Phong; Lucy, Charles A.; Mosby, Brian M.; Park, Ellane J.Using simulations offers several advantages in analytical chemistry courses. Students can explore variables faster than is often possible when using the actual instrument or method being simulated. Simulations provide the opportunity for multiple risk-free trials with instant feedback. Simulations can be used to better prepare students for upcoming laboratory experiments or to reinforce concepts covered in the classroom. Simulations can give students experience with the capabilities of an instrumental method that is not available for the laboratory portion of the course. Strategies for the effective use of simulators in active learning exercises for acid-base titrations, signal processing, cyclic voltammetry, and high performance liquid chromatography are described herein.