The effect of temperature on metabolism and oxidative damage in a lizard, Sceloporus consobrinus

Ectotherm metabolic rates positively scale with temperature. As metabolism increases, mitochondria produce more reactive oxygen species, consequently increasing oxidative damage to biomolecules such as DNA. While a recent study in ectotherms produced the expected positive relationship between temperature and metabolism, it also revealed a surprising inverse relationship between metabolic rate and oxidative damage. Our study investigates the effect of temperature manipulation on metabolism and oxidative damage in three geographically distinct populations of Sceloporus consobrinus across a latitudinal thermal gradient. Adult female lizards from each population were collected and exposed to two separate 23.5 hour temperature treatments in the lab: 18°C and 37°C. Metabolic rates were measured at each temperature, and blood samples were collected before and after each temperature exposure. Following DNA extraction and digestion, the oxidative damage biomarker 8-hydroxy-2′-deoxyguanosine (8-OHdG) was quantified for each individual using liquid chromatography with tandem mass spectrometry. As expected, our findings show that metabolic rates are higher at warmer temperatures. Further, while we did not see a change in 8-OHdG levels after the 37°C treatment, the 18°C challenge resulted in an increase in 8-OHdG levels in two of the three populations. Interestingly, lizards from the northernmost population showed resistance to oxidative damage during the cold thermal challenge. This may be due to an altered thermoregulatory strategy or a mechanism to reduce temperature-related oxidative damage. As climate change continues to amplify temperature extremes and may disproportionately impact ectotherms, it is important to understand the influence that temperature has on organismal performance.

Continue reading Nicole Joseph »

Energy Harvesting for Residential Microgrid Distributed Sensor Systems

Microgrids are localized, independent power grids that can operate while connected to the larger electrical grid. These systems make intelligent decisions regarding power management and use an array of components to monitor power generation, consumption, and environmental conditions. While this technology can save money, complex installation and maintenance has limited the adoption of microgrids in residential spaces. To simplify this technology, the next evolution of microgrid components includes sensors that are wireless and ambiently powered. Energy harvesting circuits can be incorporated into microgrid sensors, enabling them to recapture otherwise wasted environmental energy. Equipping microgrid sensors with energy harvesters simplifies the end user experience by eliminating the need for cable routing. Implementing energy harvesting techniques results in a microgrid that is easier to deploy, cleaner, and requires less maintenance. In this poster, we share the design, implementation, and evaluation of a hybrid energy harvesting and battery-powered sensor. We assessed the sensor’s performance through experiments, demonstrating its potential to operate autonomously and reliably for a decade or more without maintenance.

Continue reading Devin Whalen »

Physical Stability of Liposomes

Liposomes have proven to be effective nanocarriers of various drugs and pharmaceutical compounds. Their spherical lipid bilayer composition enables the entrapment of such molecules in their internal aqueous environment. A concern with these nanocarriers is their stability over time. Specifically, I investigated how liposomes degrade in different pH buffer solutions over an 8-day period. Fabrication of liposomes was accomplished by extruding DOPC lipids in buffer solutions of varying pH’s through a 100 nm pore size polycarbonate membrane. The samples were stored in a 70 °C recirculatory bath throughout the experiment and were tested daily. To characterize degradation, I utilized Dynamic Light Scattering (DLS) and UV-Vis spectroscopy. The DLS was used to determine average liposome size and the UV-Vis was used to determine light transmittance. We found liposome diameter increased for all pH’s with a significant increase in polydispersity among all samples. While some pH’s did cause greater increases than others, we were unable to make a strong correlation between the rate of degradation and the pH. The UV-Vis was not useful as the initial solutions were too opaque. The overall increase in polydispersity is significant because it points towards a “soup” of particles that may form from the various degradation products. These products may include various sized liposomes, long cylindrical micelles, and surfactant particles. Further study of these particles may give insight into the degradation processes occurring.

Continue reading Matt Brennan »

Telomere dynamics in Tree Swallows: exploring the effects of temperature and microbiome

As the climate is rapidly changing, many species are facing a more unpredictable and thus challenging environment. Particularly, frequent cold weather swells, known as cold snaps, have posed a significant thermoregulatory challenge that is suspected to shorten telomeres–the non-coding, protective, terminal caps on chromosomes–and ultimately reduce organismal lifespan. However, it is unknown how the composition of the gut microbiome affects an organism’s ability to face these thermoregulatory challenges. Here, we investigated the effect of temperature and antibiotics on telomere length in the widely distributed and tractable Tree Swallow (Tachycineta bicolor). Wild nestlings were reared in captivity from days five to twelve post-hatch under both cold (31ºC) and control (35ºC) conditions and further divided into two groups: antibiotic treated and non-antibiotic treated. Blood samples from twelve days post-treatment were analyzed using the telomere restriction fragment assay. While there was no significant temperature by antibiotic interaction, both warmer temperatures and antibiotic treatment resulted in individuals with longer telomeres. These findings suggest that more variable and colder climates early in the breeding season are likely to have a detrimental impact at the cellular level. Though we predicted that the administration of antibiotics may result in more telomere loss, the longer telomere average for the antibiotic treated nestlings suggests the connection between temperature challenges and the gut microbiome is complex and deserving of further research.

Continue reading Sarah Chapman »

Stroke Rehab Using Negative Stiffness Compliant Shell Mechanisms

The goal of this project was to characterize, verify, and optimize compliant shell geometry that exhibited prolonged negative stiffness. Because research into devices exhibiting negative stiffness is limited, this project added to basic scientific knowledge about such mechanical structures and added to the field’s understanding of them. In addition to this, this research worked towards helping patients in stroke rehabilitation in their journeys of recovery. The approach to this project was greatly motivated by the need for negative stiffness within a rehabilitation device. This is precisely what maximizes the efficiency of repetitive rehabilitation exercises, such as bending of the fingers for hand recovery after a stroke, which was my focus.

Continue reading Angela Ziganshina »

Life After a Secondary Music Ensemble:
An Instrumental Case Study of Former Ensemble Musicians

The purpose of this instrumental case study was to explore the experiences of former ensemble musicians and their views on collaboration during their secondary education experience. The analysis of collaboration was done through the framework of Collaboration Theory, with six components including building group cohesion, influencing others, observing and doing, organizing work, status seeking, and turn-taking. Semi-structured interviews were conducted and then coded and analyzed, then organized into themes. The participants’ responses indicated thoughtful reflection of their past experiences in middle and high school. The participants discussed and responded to questions about the individual components of Collaboration Theory and found it relevant in the secondary music classroom. They listed multiple ways their directors or peers facilitated those communal experiences, with students generally appreciating their smaller group time and an organized rehearsal space. Collaboration Theory was found to be an effective framework for discussing and implementing collaborative practices in secondary music education.

Continue reading Ryan Hill »

Diffusion in Macroscopically Layered Polymer Gels

Transdermal drug delivery is a vital mechanism for skincare, hormone replacement, and other biomedical applications. Organic polymer gels have been recently identified as candidates for this drug delivery mechanism. Our present work focuses on controlling model drug release rate in a layered polymer gel system consisting of multiple organogels and a polystyrene backing. Typically, one organogel contains a diffusion probe [AOT (sodium bis(2-ethylhexyl)sulfosuccinate)], tri-block copolymer, and an organic solvent whereas the other contains only tri-block copolymer and organic solvent. The tri-block copolymer forms a physically crosslinked network within the gels that consists of spherical polystyrene domains and a plasticized rubbery matrix consisting of ethylene-co-butylene and aliphatic mineral oil (organic solvent). The matrix phase is fluid-like and amenable to mass transport, which allows for probe diffusion. Using Fourier Transform Infrared (FTIR) spectroscopy, the overall probe release rate, which stems from this diffusion, can be tracked. In particular, we are interested in the comparison between the aforementioned layered systems and a ‘traditional’ system with a single organogel containing the AOT diffusion probe. We also seek to investigate how changing the tri-block copolymer concentration of the barrier organogel layer – that which contains no AOT – changes the overall diffusion probe release rate. Our measurements show that the release rate of layered systems exhibits a time-delay phenomenon. Furthermore, systems with higher tri-block copolymer concentration in the barrier layer exhibit a longer time delay.

Continue reading Nick DeVita »

Impact of Morphology and Polymorph on Behavior of Succinic Acid Aerosols in Mixtures with Ammonium Sulfate

Particles on the scale of nanometers are incredibly important in atmospheric chemistry due to their complex role as aerosols in the atmosphere. Atmospheric aerosols and their morphologies directly impact cloud formation, which in turn affects global warming and climate change modeling. In this project, a system of succinic acid, a dicarboxylic acid, and ammonium sulfate, an inorganic salt, was studied as both are commonly found in atmospheric aerosols. Aerosol systems are commonly studied by analyzing their size distributions, and it is expected that most systems produce a Gaussian (normal) size distribution. However, the succinic acid/ammonium sulfate system is noteworthy for containing aerosols with a bimodal size distribution. One plausible explanation for the observed bimodal size distribution is related to the polymorphism of succinic acid, as different crystal structures could produce different particle sizes.
This project utilized a syringe pump to feed aqueous solutions of varying concentrations and mixing ratios of succinic acid and ammonium sulfate into an atomizer to produce nanoscale particles. These particles were then dried and analyzed in a Scanning Mobility Particle Sizer (SMPS) system to obtain size distribution data. To test for the presence of different polymorphs in solutions of succinic acid and ammonium sulfate, particles were collected using a cascade impactor to then be analyzed with powder x-ray diffraction (PXRD) and scanning electron microscopy (SEM). The collected data allowed for the characterization of the succinic acid/ammonium sulfate system at different concentrations and mixtures of solution.

Continue reading Will Feldscher »

Beliefs about Musical Attributes
Though people dance, sing, and interact musically all across the world, there is substantial individual variation in musical abilities. What do children and adults believe about where musical abilities come from? We investigated 7- to 8-year-old children’s (N = 48) and adult’s (N = 100) beliefs about origins of musical abilities. First, children gave open-ended explanations based on prompts about musical and non-musical attributes (“There is a person who is very good at playing cello. People always clap when they play. Why do you think they are good at playing cello?”). Then, both adults and children were asked to rate how much genetic factors, environmental factors, and personal choices explained those same attributes (1 – “not at all” to 5 – “just about all”). In open-ended explanations, children tended to emphasize personal choices (e.g., “he practices a lot”). For positively-worded scale ratings, adults consistently rated personal choices highest and genetic factors lowest in importance, but again considered genetic factors to be relatively important for singing and rhythmic abilities. For negatively-worded questions, adults rated the environment highest for some of the characteristics, the outliers being singing and cello being highest in genetics and personal choice respectively. In contrast, children consistently rated environmental factors as least important, and rated genetic and personal choice factors as approximately equally important. Findings suggest that children and adults both emphasize practice and personal effort in musical skill acquisition. By adulthood, however, adults refine their beliefs about the relative importance (or unimportance) of genetic contributions to musical attributes.

Continue reading Zachary Wasserman »

How Many Passes Does it Take?
An Investigation to Determine the Optimal Number of Liposome Extrusion Cycles

Liposomes are lipid-based nanoparticles commonly known for their drug carrying capacity and value in membrane and nanoreactor research. One commonly used method of fabricating liposomes of particular size is membrane extrusion where liposomes are pushed through a porous membrane and form smaller liposomes. However, the details pertaining to liposome extrusion, such as the number of passes, membrane pore sizes, and pre-extrusion sample preparation, vary between labs. The goal of this project is to establish a relationship between the number of passes through a track-etched, polycarbonate membrane, and the average diameter and lamellarity of extruded liposomes. To investigate, we extrude samples to different amounts varying from 1 to 1,000 passes and measure the average hydrodynamic diameter and diameter distribution of each using dynamic light scattering (DLS). We measure lamellarity with small angle x-ray scattering (SAXS) and cryogenic transmission electron microscopy (CryoTEM). When liposome size distribution and lamellarity data start to flatten out, it is suggested that extrusion has been completed, and further extruding would not change the liposome size and lamellarity. These results provide researchers with the optimal number of passes for liposome extrusion that will allow them to form ideal distributions in the shortest amount of time.

Continue reading Kasey Piper »