North Carolina State University Undergraduate Symposium

2013 - 22nd Annual NC State Undergraduate Research Symposium


Eric John Alexy Chemistry
, D8
Mentor(s): Jonathan Lindsey Chemistry
Design and Synthesis of Multi-Pigment Light-Harvesting Arrays
Natural light-harvesting systems employ many pigments to absorb sunlight and transfer the resulting energy from pigment to pigment until a reaction center is reached, where conversion to chemical energy occurs.  One of the central objectives of artificial photosynthesis is to learn how to create synthetic architectures that rival, and perhaps surpass, the performance of native systems.  Nature’s pigments are hydroporphyrins such as chlorophylls (or bacteriochlorophylls) which absorb strongly in the blue and red (or near-infrared) spectral regions but are relatively transparent in the rest of the solar spectrum.  To develop broad-band absorbers for use in light-harvesting systems, several perylene-porphyrin and perylene-hydroporphyrin arrays were synthesized and their photochemical properties examined.  Each array contains an ethynyl linker joining the perylene and the porphyrin.  The synthesis follows a modular building block approach utilizing mild, copper-free, palladium catalyzed, Sonogashira coupling reactions in which a meso-bromoporphyrin (or hydroporphyrin analogue) is coupled with a perylene-ethyne, relying on preparative size exclusive chromatography (SEC) for purification.  These perylene-porphyrin arrays are attractive candidates as light-harvesting pigments for several reasons: (1) porphyrins have large molar absorption coefficients, (2) the ethyne linker increases electronic communication and thus rates of energy transfer between the perylene and porphyrin, and (3) the perylene-monoimide accessory pigment absorbs strongly in spectral regions lacked by porphyrins and hydroporphyrins.  A better understanding of the photochemical properties of these synthetic arrays can lead to the design of more efficient light-harvesting systems, a key feature of future solar energy conversion systems.

Cassandra Nicole Brinkman Biology
Emmaline Smith Human Biology;
Arushi Wadhwa Human Biology;
Amanda Pons Biology
Biological Sciences
, A7
Mentor(s): Miriam Ferzli Biology
The Use of Mathematical Modeling to Individualize Treatment of Diseases
 While the life expectancy is increasing within the U.S., the percentage of the elderly population afflicted by diseases is on the rise. Diseases target individuals differently, and so it becomes important to introduce specialized treatment. For this reason, new innovative methods that attempt to reduce disease are imperative. These innovative methods include mathematical modeling and stem cell therapy. With mathematical modeling, scientists are able to analyze biological systems and the effectiveness of treatment on diseases. For example, in one study, researchers developed a patient-specific model of a failing heart in order to aid with diagnosis for cardiovascular disease (CVD). In another study, math models were used to predict the rate at which Alzheimer’s disease leads to the deterioration of the brain. Other studies used mathematical modeling to measure the success of effector cells in fighting a tumor, and to show the progression of cancers. With stem cell therapy, it has been modeled that stem cells can be used to aid with the growth of organs after surgery in order to increase the rate of recovery. All of these studies provide examples in which mathematical modeling allowed for predictions of either disease progression or recovery rate. The objective of our analysis is to find evidence of the role of mathematical modeling and stem cell therapy in furthering research efforts for the prevention and treatment of diseases such as CVD, Alzheimer’s and various types of cancer. We also report on how these models help to individualize treatment for different patients.

Bridget Eryn Conley Microbiology
, A8
Mentor(s): Deborah Threadgill Microbiology
Jeremy Barry Chemistry
Campylobacter Invasion Antigen B of Campylobacter rectus
Campylobacter rectus is a Gram negative motile anaerobe and a putative pathogen of periodontal disease. It has also been shown to be involved in low birth weight, preterm births and other pregnancy complications. C rectus encodes a protein sharing homology with Campylobacter jejuni, Campylobacter invasion antigen B (CiaB) which aids in pathogenesis by allowing invasive activity. In the presence of female sex hormones progesterone and estradiol, the C. rectus CiaB gene was found to be upregulated as determined by RT-PCR. In order to better understand the activity of CiaB in C. rectus and its role in periodontitis, a mutant was created by deleting the CiaB gene. Invitrogen’s Gateway® cloning system was used to create a vector containing three fragments, an upstream pre-CiaB fragment, a spectinomycin resistance cassette and a downstream post-CiaB fragment. Transformation via electroporation with the targeting plasmid into C. rectus ATCC 33238 was performed. Homologous recombination occurred, resulting in the deletion of the endogenous CiaB gene and the introduction of the spectinomycin resistance cassette. The null mutation was confirmed by sequencing.

Emily Jean Cox Biological Sciences: Human Biology
Sarah Djali Biological Sciences: Human Biology;
Michael Wyngarden Human Biology;
Akshitha Vijayakumar Biochemistry;
Taylor King Microbiology;
Dorian Perez Land Development: Soil Science;
Jacob Swift Animal Science;
Julianne Black Biological Sciences: Human Biology;
Hanna Lewis Biological Sciences: Human Biology;
Christina McChesney Biology;
Matthew Walsh Biological Sciences: Human Biology;
Nathan Hoggard Animal Science
, B21
Mentor(s): James Brown Microbiology
The Prion Hypothesis: Fact or Fiction
The Prion hypothesis states that transmissible spongiform encephalopathies (TSEs) are caused by abnormal conformational changes in a normal brain protein that can be transferred from individual to individual, and from one species to another. The disease conformation of the protein (PrPSc) catalyses the refolding of normal protein (PrPc) into new molecules of the disease protein. The Prion hypothesis excludes any causative microbial or viral agent. Affected brain tissue contains vacuoles and accumulations of amyloid plaque, which seem to generate symptoms, which include dementia and behavioral and cognitive abnormalities. TSEs include scrapie (sheep), mad cow disease, and Creutzfeldt-Jakob disease. These diseases are similar in many ways to Alzheimer’s, Parkinson’s, ALS, and Huntington’s disease. The Prion hypothesis has been controversial. Recent experiments, however, have demonstrated the generation of disease from recombinant PrPSc,  a molecular analog in fulfillment of Koch’s Postulates. In addition, mice lacking the PrPC gene are not susceptible to these diseases. These demonstrate that PrPSc (prion protein) is an essential component of TSEs. However, it seems likely that other factors play significant roles in these complex diseases. In conclusion, there is now strong experimental support for the central role of prions in TSEs, consistent with the Prion hypothesis.

Alyssa Sharon D'Addezio Human Biology
Biological Sciences
, D1
Mentor(s): Heather Patisaul Biology
Hyperactivity and elevated anxiety in female prairie voles developmentally exposed to bisphenol a (BPA) is accompanied by changes in oxytocin and vasopressin neuron numbers.
In rats and mice, developmental exposure to Bisphenol A (BPA) has been shown to cause changes in behavior related to anxiety and sociality. The mechanisms by which this occurs and the human relevance of these behavior changes remain largely unknown.  To investigate these effects resulting from developmental exposure to BPA, we used a unique rodent model, the prairie vole. Prairie vole pups were divided into a vehicle control group and three orally administered BPA exposure groups: 5 mg/kg, 50 mg/kg, and 50 mg/kg. The voles were tested in open-field, novel-social, and partner preference tests. Because the oxytocin-vasopressin (OT/AVP) system feeding into limbic dopaminergic pathways is critical for the manifestation of sociality, we then immunolabeled and counted OT and AVP neuron numbers in the paraventricular nucleus of the hypothalamus (PVN). Behavioral effects were dose-dependent and most pronounced in females with evidence of increased anxiety and decreased activity levels in the 50 mg/kg BPA exposure group and hyperactivity in the 5 mg/kg exposure group. The 50 mg/kg BPA exposure group in the female voles showed decreased OT neuron numbers in the posterior PVN and increased AVP neuron numbers in the anterior PVN compared to controls. These data support the hypothesis that BPA alters anxiety and exploratory behavior patterns possibly through the OT/AVP pathway and that exposure to chemicals during development may contribute to the incidence of human affective disorders such as autism, ADHD, and other behavioral disorders.

Mithi Alexa De Los Reyes Physics, Mathematics
, C12
Mentor(s): John Blondin Physics
Two- and Three-Dimensional Turbulence in Core-Collapse Supernovae
The Spherical Accretion Shock Instability (SASI), in which a supernova shock wave stalls and produces a turbulent post-shock flow, has generally been accepted as an important phenomenon in core-collapse supernovae. However, the ef ects of the turbulence caused by the SASI have not yet been thoroughly investigated. Indeed, while the scaling laws of turbulence are theoretically expected to behave differently in two and three dimensions, no full comparison has yet been made between two- and three-dimensional SASI-driven turbulence. We therefore use high-resolution hydrodynamic simulations of core-collapse supernovae to study the growth of this turbulence. We produce and analyze spherical harmonic power spectra in order to quantify energy conversion (i.e. gravitational potential energy to the kinetic energy of turbulent flow) on diferent length scales. Finally, this allows us to determine and compare which scaling laws best describe the turbulence in different dimensions. 

Jacquelyn Lee Fitzgerald Biology
Kelly Henkel Genetics and Plant Biology;
Grace Jou Zoology;
Courtney Bachman Natural Resources
Biological Sciences
, A4
Mentor(s): Miriam Ferzli Biology
Species Adaptations to Environmental Stressors
Human interactions with the environment are often at the root of many environmental stressors. One in particular is hydraulic fracturing, the use of water and chemical fluids coupled with intense pressure to drill horizontally for natural gas. Hydraulic fracturing may be a factor in increasing concentrations of hazardous chemicals, isotopes, and gases in shallow aquifers. In response to these sorts of pressures, species populations may react in a myriad of ways.  Any sort of disruption of the ecosystem may result in habitat tracking (in which organisms leave the environment), genetic change, altered interspecies interactions, or extinction.  Change in one species impacts the local biological community and may lead to global shifts in ecosystems.  The impact of these stressors may be demonstrated in coral and seaweed populations.  In response to the effects of climate change, these populations have shown altered interactions with other species, a decrease in reproductive fitness, and movement towards extinction.  Rapid environmental changes are often detrimental, since organisms do not have an opportunity to adapt. This is most evident in species with long life spans. In populations with low rates of diversity, these stressors are likely to cause extinction.  Without genetic variability, selection for more heat tolerant individuals is unlikely to occur.  The objective of this work is to illustrate how specific stressors affect biological systems.

Analiesel Eva Hannes Microbiology and Food Science
Food, Bioprocessing, and Nutrition Sciences
, D14
Mentor(s): Lee-Ann Jaykus Food, Bioprocessing & Nutrition Sciences
Persistence of Tulane Virus on Stainless Steel
 Human noroviruses (HuNoV) are the most common cause of acute viral gastroenteritis and a leading cause of foodborne disease. Transmission occurs when an infected host or contaminated surface comes in contact a food product, which is then consumed. HuNoV are highly infectious, but few studies have been done assessing their persistence on surfaces, largely due to the fact that these viruses cannot be cultured in vitro. As a result, the use of cultivable surrogates is necessary. The purpose of this study was to evaluate the persistence of Tulane Virus, a recently discovered HuNoV surrogate that can be cultured on primate cells. In the first round of experiments, the virus was inoculated onto stainless steel coupons and eluted over a period of 0 to 42 days. Quantitative reverse transcription-polymerase chain reaction (RT-qPCR) was used to quantify virus persistence. An RNase treatment was applied to an aliquot of the elution prior to nucleic acid extraction to distinguish infectious from non-infectious, surviving viral particles. Results showed an overall decrease in the concentration of virus over the 42 days, with a 2-log10 reduction occurring in the first week and only a 0.3-log10 reduction occurring in the following 5 weeks. There was not a large difference in virus titer, whether or not detection was preceded by an RNase treatment. Additional studies are underway to use mammalian cell culture to evaluate virus persistence on the basis of infectivity. Together, these studies will allow us to compare RT-qPCR to infectivity assay, and develop data to compare the persistence of Tulane virus to HuNoV.  

Hope Alexandra Hendricks Biology
, B20
Mentor(s): David Threadgill Genetics
Differentiating Induced Pluripotent Stem Cells into Hepatocyte-like cells
The generation of mature hepatocyte-like cells is of particular medical interest as liver transplantation is currently the only available treatment for end stage liver diseases. Current research involves developing efficient procedures to differentiate induced pluripotent stem cells into hepatocyte-like cells. This research repeated a 12-day protocol to derive hepatocytes from mouse iPS cells using three different differentiating medias. The purpose of the medias was to transform the iPS cells into definitive endoderm, hepatic commitment cells, and lastly into mature hepatocyte-like cells. The results showed clear morphological transitions from iPS cells, but PCR analysis of the definitive endoderm marker Sox17 did not show significant differences between treated and untreated 429 iPS cells after the first media treatment. Further, application of the three step protocol to WSBxNOD 2.5 cells, which morphologically resemble the human iPS cells used in the original research, did not show any more promising results after PCR analysis of Sox17. Future research will involve pinpointing the correct media treatment and cells to successfully reach definitive endoderm. Gene analysis on specific marker genes of the mature hepatocytes will determine the overall success of the protocol.

Laura Ashley Icenhour Biology
Animal Science
, A20
Mentor(s): Chad Stahl Animal Science
The effects of an obesigenic diet on growth, bone composition and activity of mesenchymal stem cells in Yucatan miniature swine
Formula feeding during infancy has been associated with heightened risk for childhood and later life obesity. High sugar and saturated fat diets are common cause for development of childhood obesity. We examined the effects of an obesigenic diet on bone integrity and mesenchymal stem cell (MSC) differentiation in young Yucatan miniature swine.  Artificially fed animals received a milk replacer formulated to match sow milk, while sow-reared animals remained with their mothers until weaning. Animals were then put into 2 weaning groups; obese (O) and control (C). The O group was fed a high fat, high fructose diet ad libitum for 1 hour, 2 times per day. After measuring intake for the O group, the C animals received 50% by weight of their lean feed at each feeding. Feed intake was measured daily, and bodyweights were obtained weekly. ADG, ADFI and feed efficiency were all increased in the O animals (P<0.05). At the end of the study, O had larger, heavier bones with higher bone mineral content than did the C piglets, as indicated by longer length and higher ash percentage in the humerus and radial bones (P<0.1).  MSC from the Yucatan piglets did not differentiate as expected when treated with adipocytic and osteogenic induction medias. For this reason, gene expression was not performed. More work needs to be performed to optimize appropriate media recipes to achieve differentiation in these aging MSC.

William Zachary Jahn International Studies
Interdisciplinary Programs
, D26
Mentor(s): Anne Clement History
Japanese Competitive Education and Social Development Problems
Since the end of World War II, Japan’s educational ideology has seen a shift towards a more competitive nature. This competitive nature can arguably be attributed to Japan’s post war economic success. With the bursting of the economic bubble however, this competitive educational system is no longer producing the expected results of guaranteed lifelong career tracks. Even more significantly, the combination between the effects of the economic recession and the increasingly high rates of juvenile suicide seems to indicate that the Japanese educational system has become a problematic and controversial structure that contributes to growing social development problems among adolescents. This paper aims to further explore the relationship between Japan’s competitive educational system and the growing psychological conditions developed by the youth. It will show more specifically that, while a direct causal link is hard to prove, a strong correlation between both elements exists nonetheless. This correlation will be examined through a study of the following phenomena: the effects of the competitive nature of middle school cliques, bullying (ijime), severe social withdrawal (hikikomori), and eventually extreme instances such as the Aum Shinrikyo terrorist attack, and Japan’s rising problem of adolescent suicide. 

Nasir Khatri Biology
Biological Sciences
, A2
Mentor(s): James Knopp Biochemistry
Investigating Differences in Tissue Perfusion in the Elderly Following Regional Specific Training Stimulus or Aerobic Training
The existing standards of aerobic training and gradual progression into whole-body exercise for the elderly may be less than optimal. In this study, we examined the effects of 8 weeks of traditional aerobic plus resistant (AT+RT) exercise training preceded by 4 weeks of either 1) regional specific training stimulus (RSTS) (n=20), our novel exercise training protocol, or 2) AT (n=18) on skeletal muscle deoxygenation in frail elders. Near infrared spectroscopy was used to measure gastrocnemius muscle deoxyhemoglobin concentrations (HHb) during cardiopulmonary exercise testing at weeks 0, 4, and 12 of training. We hypothesized that RSTS would increase tissue perfusion during exercise to a greater extent than AT. There were no significant differences in tissue perfusion between RSTS and AT at week 0 (HHb: 3.907±2.469 v. 3.465±2.545, respectively; p=1.000), week 4 (HHb: 6.690±2.528 v. 4.802±2.756, respectively; p=0.9958), or week 12 (Hb: 1.607±2.740 v. -1.998±2.938, respectively; p=0.9455), and, despite significant improvements in fitness in both groups, there were no improvements in tissue perfusion in either group in response to exercise training. Further studies are needed to determine whether: 1) tissue perfusion is a limiting factor for exercise capacity in this population, and/or 2) NIRS is sensitive enough to detect modest changes in tissue oxygenation in healthy subjects. 

Kristen Nicole Leger Biochemistry
, C12
Mentor(s): Gang Lu Structural Biology
Crystal Structure of the NYN Domain of MCPIP1
Monocyte chemotactic protein-1 induced protein-1 (MCPIP1), which is encoded by the gene zc3h12a, plays important roles in the regulation of cellular inflammatory response and microRNA biogenesis. MCPIP1 contains an ubiquitin binding domain, a Nedd4-BP10, YacP Nuclease (NYN) domain, and a single CCCH-type zinc finger domain. MCPIP1 is essential in the prevention of immune disorders.  MCPIP1 knockout mice spontaneously died within 12 weeks of birth, and many of them suffered growth retardation, as well as severe splenomegaly and lymphoadenopathy. Additionally, the MCPIP1 -/- mice developed hyperimmunoglobulinemia relative to all immunoglobulin isotypes evaluated. MCPIP1 is responsible for regulating the stability of interleukin-6 (IL-6). The MCPIP1 knockout mice had increased levels of IL-6 mRNA. MCPIP1 has also been shown to antagonize the ribonuclease Dicer in microRNA biogenesis. It can cleave the terminal loops of microRNA precursors (i.e. pre-let7, pre-miR146a, and pre-miR135b) to inhibit the maturation of microRNAs. We determined the crystal structure of the MCPIP1 NYN domain in complex with Mg2+ and revealed that NYN adopts a FLAP-PIN domain fold. The Mg2+ ion is coordinated by the side chain of an aspartate residue in the active site and 5 water molecules. The crystal structure shed light on the RNA recognition by MCPIP1 and the cleavage of terminal loops of microRNA precursors.    

Joseph Andrew Murray Mathematics
, B11
Mentor(s): Carl Meyer Mathematics
Beating the Oddsmakers -- Modifying Sports Rating and Ranking Methods to Improve Predictive Success
The topic of rating and ranking sports teams has risen in significance since the inception of the Bowl Championship Series, with large amounts of fame and fortune awarded to those football teams which are selected (based on rankings) to compete in postseason bowl games. Rankings are determined, among other things, by computer ranking systems which utilize topics from Linear Algebra to calculate unbiased rankings based on team performance in a given season. Additionally, these ranking methods can be used to predict winners of games by assuming that a high ranked team will beat the teams ranked below it. I analyzed the predictive accuracy of several popular ranking methods, with a focus on determining which factors of a ranking method aid in accurate predictions. I used sports data from the 2012-2013 NCAA Division I college basketball season as my input and found that the Colley method was the most successful with a natural predictive accuracy of 76.39%. I also found that, against intuition, modifying the Colley method resulted in reduced predictive accuracy; however, modifying other methods resulted in higher predictive accuracy. Throughout my research, the one factor that most often improved predictive accuracy was the inclusion of a cap on margin of victory, with noticeable improvements in both an Offense-Defense model and an Elo-based method. These results imply that the predictive success of a ranking method can vary depending on the method, and that no sole component will always increase or decrease predictive success.

Madison Brooke Owsley Biology
, A19
Mentor(s): Michael Hyman Microbiology
Isolation and characterization of novel isobutylene-utilizing bacteria
 A variety of aerobic bacteria are known to grow on simple alkenes but currently only one bacterium (Mycobacterium sp. ELW1) has been identified that grows on the simplest branched alkene, isobutylene (2-methylpropene). Isobutylene metabolism in strain ELW1 is dependent on cobalt as a key enzyme involved in the pathway of isobutylene metabolism (2-hydroxyisobutyrate mutase) contains cobalamin. Strain ELW1 is also capable of degrading a number of environmental pollutants such as 1,4-dioxane (14D). In this study I have isolated two new strains of isobutylene-metabolizing bacteria. I have also examined whether growth of these strains on a key intermediate in the pathway of isobutylene metabolism is cobalt-dependent and examined whether these strains can also oxidize 14D after growth on isobutylene. The two new strains were isolated by enrichment cultures using a variety of hydrocarbon-impacted soil samples as inocula. After repeated subculturing, the purity of the isolated strains was established by streaking the cultures and by microscopic analysis after gram staining. One strain, MO1, was shown to be a gram+ rod, the other strain, MO2, was shown to be a gram+ coccus. Unlike  strain ELW1, growth of both strains MO1 and MO2 on 2-hydroxyisobutyrate was unimpacted by eliminating cobalt from the growth medium. This result suggests that strain MO1 and MO2 both potentially utilize a different pathway of isobutylene metabolism than strain ELW1.  In initial experiments, isobutylene-grown cells of strain MO1 also oxidized 14D, as determined by gas chromatography. Additional studies will aim to identify the key intermediates in the pathway of isobutylene metabolism by these strains as well as the kinetic characteristics of 14D degradation by these organisms.

Charles H. Parrish II Biological Engineering: Environmental Engineering
Plant Biology
, B17
Mentor(s): Imara Perera Plant Biology
A comparative study of experimental systems for plant responses to low phosphate
Phosphate is an essential macronutrient for many cellular processes in plants. Inositol hexakisphosphate (InsP6) is a major storage form of phosphate in plants and IPK1 is a key enzyme in InsP6 synthesis. The Arabidopsis thaliana ipk1 mutant exhibits defects in sensing external phosphate. The goal of this study was to further investigate the role of IPK1in plant responses to low phosphate. For this study we employed three different experimental systems, an agar-plate based method as well as seedlings in liquid culture and a hydroponic system for mature plants. In each set of experiments, wild type and ipk1 plants were grown under sufficient or limiting phosphate and tissue was sampled for inorganic phosphate (Pi) content. Typical morphological responses to low phosphate include changes in primary root growth and agar plate-based assays are the most suited for measuring changes in root architecture under varying low phosphate concentrations. Two methods of hydroponics were optimized for testing of molecular responses at specific time points. A liquid culture system was used to monitor rapid short term responses of seedlings to low phosphate and a box-based hydroponic system was used to monitor root and shoot responses of mature plants. The results of each experiment, as well as the advantages and disadvantages of each growth method, will be discussed.

Megan L Perry Food Science
Johnathan Jackson Food Science;
Ashleigh Stephens Food Science;
Molly Spencer Food Science
Food, Bioprocessing, and Nutrition Sciences
, D26
Mentor(s): Brian Farkas Food, Bioprocessing & Nutrition Sciences
Formulation of a Low Sodium Frankfurter
Carolina Packers needs to reduce the sodium content of their Bright Leaf Red Hot Dog formulation in an effort to provide healthier options to children in local school systems. In frankfurters, sodium chloride (NaCl) has three important functions: texture, flavor, and preservation. The goal for this project was to develop a frankfurter formulation with less sodium without compromising the flavor, appearance, texture, or preservation properties of the company’s current formulation. Three batches were processed in the Carolina Packers plant: two lower sodium formulations (one with 17% NaCl reduction and one with complete replacement of NaCl with Morton’s Lite Salt^TM Mixture) and a control (the original frankfurter formulation). Sodium analysis was performed to determine that sodium was reduced from 2.4% to less than 2.0% in each test formulation. Several analyses were conducted to determine if the lower sodium formulations significantly affected the consumer perception, color, preservation, or texture of the product. It was found that the color, pH, water activity, purge loss, and aerobic plate count did not vary significantly between the three formulations over the twenty-one day shelf-life. Triangle tests were performed to determine if consumers could distinguish the difference between control frankfurters and lower sodium frankfurters. In both tests, slightly over half of the participants were able to tell the difference between the control frankfurters and lower sodium frankfurters. Texture results indicated that both lower sodium formulations had a softer exterior and interior when compared to the control frankfurters. This could be improved by modifying the ingredients.

Marie-Louise Posch Biology
Computer Science
, D7
Mentor(s): Donald Bitzer Computer Science-Engineering
Robert Rodman Computer Science-Engineering
Speaker Identification of a Ventriloquist Through Her Puppet Voices
     The purpose of this project is to explore the possibility of identifying a ventriloquist by a computational analysis of the ventriloquist’s normal voice and her four “puppet” voices. As current literature suggests, using a ventriloquist is a completely new way to examine the effectiveness of disguised voices in computer-aided speaker identification. It is hoped that the findings of this project will bring new insight into the field of computational linguistics and advance the current research involving speaker recognition. One field where the results of this study could be applied is law enforcement and security. Since a ventriloquist does, in effect, disguise his or her voice when making a puppet speak, our study asks whether such a disguise is effective in concealing the identity of the speaker. If it is possible to “see through” a disguised voice, it may then be possible to identify the person. To accomplish the objective, multiple pronunciations of three vowel phonemes of English: /i/ representing the vowel in meet; /u/ representing the vowel in /boot/ and /ae/ the single vowel phoneme in cat have been isolated and analyzed. By isolating the different phonemes, computer software can be used to identify the formant pattern of each vowel for each voice. Statistical methods may then be used to analyze the measurements and determine the likelihood of the puppet voices revealing the identity of the ventriloquist.

Ashley Elizabeth Quick Wood and Paper Science/Chemical Engineering
Forest Biomaterials, Wood & Paper Science
, C27
Mentor(s): Richard Venditti Wood And Paper Science
Hemicellulose as a replacement for petroleum based polyols in the paper coating industry
 Hemicellulose is a green substitute for petroleum based polyols and is a non-food based substitute for starch polyols. It is also a byproduct of an associated industry – the paper industry – and is available in large quantities. Hemicellulose is a long chain material bearing hydroxyl groups which associate with hydrophilic solvents; however, once crosslinked with Zirconium salt, the product is a more or less rigid gel that is water resistant upon drying. This makes Hemicellulose a viable raw material for the coating industry. In the first part of our research, an alkaline treatment was applied to switchgrass, pine wood and Coastal Bermuda Grass in order to extract hemicelluloses to subsequently produce a new product for coating applications. An extraction at 75°C recovered 27% of the biomass as a predominantly hemicellulose material with a number average degree of polymerization of 500 determined by gel permeation chromatography The product was characterized by FTIR spectroscopy, gel permeation chromatography for molecular weight and water contact angle analysis. The results obtained indicate a promising combination between the effective extraction of hemicellulose from grasses and an environmentally friendly process to generate hemicellulose with high degree of polymerization for use in various industrial applications as coating applications.  The second part of this project, not shown here, is about using the extracted hemicellulose to synthetize a biodegradable hemicellulose coating insolubilized which is an innovative and important issue in coating engineering chemistry.

Richard William Schaefer Polymer and Color Chemistry
Textile Engineering, Chemistry & Science
, D17
Mentor(s): David Hinks Textile Engineering Chemistry and Science
Keith Beck Textile Engineering Chemistry and Science
Forensic Analysis of Fiber-Reactive Dyed Cellulose by Enzyme Digestion, Liquid Chromatographic, and Mass Spectrometric Methods
Forensic scientists utilize fiber trace evidence as circumstantial evidence to indicate contact between people and objects. One method for identifying fibers is by their color. Current methods for identifying the dyes present in cellulose dyed with fiber-reactive-dyes lack accuracy, specificity, and repeatability. Additionally, many test methods require dye extraction, which is difficult for cellulose reactive dyes because they covalently bond to cellulose. One potential method for identifying these reactive dyes that are bound to cellulose is to hydrolyze the glucosidic linkages to release the original dye, or with the original dye-fiber covalent bond intact but with glucose or cellobiose substituents.  In this way, analysis of the non-polymeric derivatized dye becomes possible via High Performance Liquid Chromatography and Time-of-Flight Mass Spectrometry. A set of fiber-reactive dyed cotton samples were prepared, and a method was established using cellulase-based enzymes to digest them. One set of dyes was analyzed using HPLC; the chromatograms for the digested samples were unique indicating that the test method may be viable after optimization of the mobile phase and column. Analysis of enzyme-digested cotton dyed with C.I. Reactive Blue 19 via a modified mobile phase and column using HPLC and TOF MS identified the dye attached to glucose and cellobiose units. Further attempts were made to refine the HPLC separation method to make it suitable for all reactive dyes, but a generic method has not yet been identified. Direct Injection TOF MS revealed the presence of unknown ions that could be masking the digested dye signal. 

Christopher Allen Stanbery Marine Earth & Atmospheric Sci
Marine Earth and Atmospheric Sciences
, D23
Mentor(s): Karl Wegmann Marine,Earth & Atmospheric Sci
Beaver dams and stream evolution in the Piedmont of North Carolina

Prior to the arrival of European settlers, beavers acted as bioengineers significantly modifying the flux of water, sediment, and organic matter along streams and rivers across North America.  The sharp decline in their populations and the subsequent dramatic shift of land use brought about by the arrival of these people had an extensive and lasting impact on valley bottoms across the continent.  As millions of dollars are spent on stream restoration, the historic and future role of beavers in modifying and maintaining stream systems must be established.  While increasing amounts of research are being done in the western U.S., less work has been done to understand what part beaver dams play in the eastern U.S, especially along streams draining the Piedmont of North Carolina.  Historic Yates Mill County Park (Wake County) has an active beaver re-colonization site.  We hypothesized that the presence of beaver dams along Steep Hill Creek would improve water quality and stream health by serving as a sink for total suspended solids (TSS) and excess nutrients.  We collected a suite of water quality parameters, TSS measurements, and radiocarbon dated stream-bank sediments in order to test whether the beaver dam complex serves to minimize the impacts to downstream water quality during storm events.  Preliminary results indicate that the beaver dam is an effective trap for TSS. Though there is a great deal more data to collect, this initial study shows that beavers play a vital role in creating and maintaining a healthy, natural river system.

Kelly "Ashton" Thompson Horticultural Science
Horticultural Science
, D3
Mentor(s): Helen Kraus Horticultural Science
Eggshells as a potential organic liming agent for aquaponic systems.


Aquaponics is the integration of aquaculture and hydroponics into a unique symbiotic ecosystem in which the fish provide nutrients for the plants and the plants filter potentially harmful nutrients out of the water for the fish. Beneficial bacteria mediate nutrient cycling resulting in the release of hydrogen ions, thus lowering the culture water’s pH. Aquaponic systems have a target pH of 7.0 which is typically maintained through the use of calcium hydroxide and/or potassium hydroxide, both chemically manufactered. For this experiment we tested the use of egg shells as an organic liming agent in an aquaponic system. Our results showed that egg shells can be used as an effective liming agent in place of calcium hydroxide in an aquaponic system.

Michael Anthony Valeri Chemical Engineering
Chemical & Biomolecular Engineering
, B21
Mentor(s): Michael Dickey Chemical & Biomolecular Eng
Tuning the yield properties of a semiconducting membrane (Ga2O3) on a liquid metal alloy (Eutetic Gallium Indium) by Water
The aim of this research is to study, control, and manipulate the properties of a passivating surface oxide (Ga2O3) layer (skin) that forms spontaneously at ambient temperature on a room temperature liquid metal alloy, eutectic gallium indium (EGaIn).  This semiconducting skin (or nanofilm) acts like a flexible membrane that provides mechanical stability to the high surface tension, low viscosity liquid metal such that it can be molded into useful shapes (e.g., antennas, interconnects, self assembled monolayer and electrodes).  Rupturing this semiconducting nanofilm allows the metal to flow (e.g., into microfluidic channels to define its shape) and provides a method to create conductive structures that change shape, and therefore function, in response to stimuli.  We seek to understand and manipulate these properties by water to better control the shape of the metal. 
Rheology provides fundamental and quantitative information about the behavior of this skin under various mechanical and chemical environments.  In a stress controlled rheometer, parallel plates sandwich EGaIn and measure the modulus and yield stress of the skin by oscillatory stress-strain measurements.  The mechanical properties of EGaIn on the micro scale can be tuned by modifying the skin.  The results suggest that certain environments (water) weaken the skin and others (polyvinylalcohol) reinforce the skin. We also tested these hypotheses by measuring the critical pressure to flow egain into a capillary, surface characterization by XPS, and simple tilt drop tests with or without water.

Ty B Wagoner Food Science
Krisha Patel Food Science;
Caitlin Alberts Food Science;
Lauren DePalma Food Science
Food, Bioprocessing, and Nutrition Sciences
, A27
Mentor(s): Brian Farkas Food, Bioprocessing & Nutrition Sciences
Comparing effects of thermal processing on bioactive immune compounds in human milk
Human milk from donor milk banks is available to premature infants that do not have access to their own mother's milk. Human milk is unique in its ability to provide nutrients and immune factors that aid the underdeveloped neonatal immune system. The milk is pasteurized using a Low-Temperature Long-Time (LTLT) method called Holder pasteurization (62.5°C for 30 min). While effective at inactivating potential pathogens, the thermal treatment also destroys many important biologically active proteins. High-Temperature Short-Time (HTST) pasteurization (71.7°C for 15sec) has also been studied with human milk. Recent studies have suggested that this thermal treatment is less destructive to the heat sensitive proteins, with a lysozyme retention rate of 80% compared to 65% for LTLT. However, the financial investment for HTST pasteurization equipment is not feasible for most donor banks. Utilizing a controlled temperature water bath, this study seeks to determine if a higher temperature and shorter batch pasteurization time will provide greater retention in bioactive proteins. This data will be used to identify an improved processing time and temperature combination for donor milk. Several variables of the thermal process will be studied, including the time and temperature combination and three different package types: plastic, glass, and a multi-layer aluminum polyethylene terephthalate pouch. Data will be collected to study the effects of these treatments on two important heat sensitive bioactive compounds, secretory IgA (sIgA) and lysozyme, and on aerobic bacterial counts to validate the thermal process.

Eric Whitmire Computer Science and Biomedical Engineering
Electrical & Computer Engineering
Mentor(s): Alper Bozkurt Elec & Comp Engineering
Test Platform for Automated Control of Terrestrial Insect Biobots
Centimeter scale mobile biobots offer unique advantages in uncertain environments. Previous experimentation has demonstrated neural stimulation techniques in order to control the motion of Madagascar hissing cockroaches. These trials relied on stimulation by a human operator using a remote control. We have developed a Kinect-based system for computer operated automatic control of cockroaches. Using image processing techniques and a radio transmitter, this platform both detects the position of the roach biobot and sends stimulation commands to an implanted microcontroller-based receiver. The work presented here enables repeatable experimentation and allows precise quantification of the line following capabilities of the roach biobot. This system will help refine our model for the stimulation response of the insect and improve our ability to direct them in increasingly dynamic situations.

Eric Warren Wilbanks Spanish
, B14
Mentor(s): Robin Dodsworth English
Pitch and VOT as Factors in the Perception of Sexual Identity and Masculinity in Male Speech
Language is a crucial medium for the creation, presentation, and perception of multiple intersecting aspects of social identity, including sexual identity. Previous research has shown that listeners are extremely skilled at identifying a speaker’s sexual identity just by listening to his/her speech. However, results have been mixed as to which specific linguistic features contribute to listeners’ perceptions. The current study investigates the effect of raising pitch 15Hz, lowering pitch 15Hz, and doubling voice onset time (VOT) in voiceless stops (consonants) for the words pocket, cap, token, and coat produced by four speakers, two of whom self-identified as gay and two of whom self-identified as straight. These stimuli were rated by a group of 71 listeners along seven-point Likert scales for the following parameters: Gay/Straight, Educated/Uneducated, and Feminine/Masculine. Quantitative analysis of the results shows that listeners rated each of the speakers consistently across stimuli, despite the fact that they were presented with 58 separate stimuli over the span of 30 minutes. However, raising the pitch 15Hz caused listeners to rate the self-identified straight speakers as less straight and less masculine. Other within-speaker effects were much weaker than the overall differences between speakers. These data prove that speakers are able to consistently perceive speaker-level differences in identity through hearing single words in isolation. They also suggest that pitch is a linguistic resource used in the perception of sexuality and masculinity in men to a greater extent than VOT.

Alex Shaun Woodrow Chemical Engineering
Chemical & Biomolecular Engineering
, D20
Mentor(s): Richard Spontak Chemical and Biomolecular Engineering
May Hägg Chemical Engineering;
Iman Soltani Chemical & Biomolecular Eng
Use of Block Ionomers and Their Blends for Gas Separation
Efficient separation of contaminant molecules, such as CO2 and NH3, from industrial gas streams is problematic. Although such gas separation remains the focus of ongoing research, effective means of separation are usually expensive. Gas separation processes based on polymer membranes constitute a promising alternative to adsorbents and liquid scrubbers because they are relatively inexpensive, mechanically durable, and are easily tailored for specific processes. The focus of this study has been to examine the gas transport properties of a new block ionomer and discover its effectiveness at removing contaminant molecules from gas mixtures. The polymer used in this work is a poly[tert-butylstyrene-b-(ethylene-co-propylene)-b(styrene-r-styrene sulfonate)-b-(ethylene-co-propylene)-b-tert-butylstyrene] pentablock ionomer. Unlike conventional block copolymers, the midblock is selectively sulfonated. Materials with discrete degrees of sulfonation ranging from IEC 1.0 to IEC 2.0 have been tested. For pure-gas permeation testing, ionomer films measured approximately 200 μm thick and were prepared as two different morphologies. The first morphology was the as-received morphology wherein the olefinic and styrenic groups constitute the continuous matrix. This morphology was prepared by welding several films together at approximately 110°C to create the targeted 200 μm film. The second was an inverted morphology prepared by solvent casting from tetrahydrofuran, in which case the sulfonated midblock formed the matrix. The permeability of each gas through these materials was then compared to each other. It was shown that CO2 caused plasticization and increased the permeability of the material. In companion studies, the permeability of NH3 in the presence of water is remarkably high relative to other gases, indicating that these materials may be uniquely suited for removal of ammonia from methane derived from biomass.