Master's Theses
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Item An Evaluation of a Northern Bobwhite (Colinus virginianus) Parent-reared Release in South CarolinaHaley, RyanNorthern bobwhites (Colinus virginianus) have experienced large, range-wide declines mainly attributed to the loss of early-successional habitat. Bobwhite population recovery is predicated on sound habitat management. Even when adequate habitat exists, low bobwhite densities and limited dispersal capabilities may limit population recovery. Restocking techniques, including release of pen-reared birds, wild bobwhite translocation, and the use of wild-strained, parent-reared captive-raised bobwhites have been explored as surrogates to natural recolonization. In this study, I evaluated survival and reproduction of parent-reared bobwhites, compared to resident bobwhites, on a private property in South Carolina from April 2009-April 2013. I used a sequential modeling approach to evaluate adult survival and nest survival using Program MARK. Bobwhite survival was best explained by temporal (annual and weekly) effects and group (parent-reared vs. resident) effects. Weekly bobwhite survival for both parent-reared and resident bobwhites was too low to produce a stable population. Parent-reared bobwhite survival was lower than resident bobwhites during the first 3 weeks post-release but similar during later weeks. Parent-reared bobwhites released in August had higher survival (S = 0.884, 95% CI = 0.862, 0.903) than birds released in early fall (S = 0.707, 95% CI = 0.621, 0.782). Nest survival and other reproductive parameters for parent-reared and resident bobwhite were similar. The viability of the parent-reared release system as a restocking technique is limited as currently constructed and future modification is needed if it is to produce a viable bobwhite populationItem Bat Activity on Golf Courses in DelawareWallrichs, MeganDue to landscape modifications and chemical use, golf courses have earned a negative reputation among some environmental groups, but their park-like landscapes may offer habitat for some wildlife species, especially over other land use types. In this study, I monitored bat activity using ultrasonic acoustic detectors in different small-scale habitats found on golf courses on the Delmarva Peninsula. My objective was to evaluate if and how bats are using course landscapes. I found differences in overall activity levels at the habitat level but not on different golf courses. Areas with closed canopy and open understory that were managed had significantly higher activity than other four habitats that reflected more natural habitats (open grass, dense canopy forest fragment, and open canopy forest fragment). The open understory managed areas also had significantly higher foraging activity than the other four habitats. Six of the eight bat species thought to occur on the Delmarva Peninsula were recorded, but Eptesicus fuscus and Lasiurus borealis dominated bat activity across all golf courses and habitats and had highest activity in open understory managed habitat. These findings indicate that bats are using golf courses on the Peninsula regularly as flyways and foraging grounds, and even substantially disturbed areas are used extensively. This study adds to the growing body of literature that positive partnerships can be created between wildlife and golf courses.Item In vitro Assessment of Phytoconstituents, Efficacy and Cytotoxicity of Extracts from Medicinal Plants on Prostate Cancer C4-2 CellsAsuzu, Peace ChiamakaPhenolic compounds are products of secondary plant metabolism known for their biological activity including their antimicrobial, antioxidant, analgesic, stimulant, anti-carcinogenic, and aphrodisiac properties. The main objective of this study was to assess the content and properties of bioactive phytochemicals in the extracts of Prunus africana, Pausinystalia yohimbe, Moringa oleifera, Momordica charantia and Orthero spp and determine their potency/cytotoxic effects. Total phenolics (TPC), carotenoids, anthocyanins, and flavonoids and their antioxidant properties in water, ethanol, methanol, acetone, and dichloromethane extracts of the different plant parts of these five plants were measured using the Folin-Ciocalteu, 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity (DPPH), ferric reducing antioxidant power (FRAP), and 2,2′-Azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) radical scavenging (ABTS) assays. For most of the plant samples, extraction yields were highest in ethanol or methanol extraction solvents. The highest total phenolic content (1397.33 mg GAE/g) was seen in the methanol extract of P. africana bark from Cameroon, while the acetone extract of M. charantia leaves yielded the highest total flavonoid content (217.33 mg RU/g). The FRAP values in this study ranged from 7.09 in the DCM extract of P. africana bark (Kenya) to 131.57 mM Fe2+/g in ACE extract of M. charantia leaf. The EC50 values for the acetone and methanol extracts of P. africana bark (Cameroon), methanol and ethanol extracts of P. yohimbe leaf and the methanol extract of P. yohimbe root were comparable to ascorbic acid (0.18 mg/mL). TPC showed a strong positive correlation with TFC of acetone extracts of P. yohimbe and Orthero roots, FRAP of ethanol and methanol extracts of P. africana (Cameroon) root, acetone and methanol extracts of P. africana (Cameroon) leaf, methanol extracts of P. yohimbe leaf, M. charantia leaf and the TEAC of P. africana (Cameroon) bark water extract, ethanol extracts of P. yohimbe leaf and Orthero root. Using high performance liquid chromatography (HPLC), seven phenolic acids, namely methyl 4-hydroxybenzoate, protocatechuic acid ethyl ester, trans-sinapic acid, vanillic acid, trans-ferulic acid, p-coumaric acid and caffeic acid were isolated from nine extracts of P. africana and P. yohimbe. The most abundant phenolic acids were vanillic acid (116.41 mg/g dry extract in methanol extract of P. yohimbe leaf) and trans-sinapic acid (102.22 mg/g dry extract in water extract of P. africana bark). On gas chromatographic phytosterol analysis, stigmasterol, β-sitosterol and campesterol were present in all plant parts of P. africana and P. yohimbe except for P. africana root and bark, where campesterol was not detected. β-sitosterol showed the highest concentration and variation between plant parts, ranging from 0.55-2.26 in the bark and leaf and 0.35-0.46 mg/g in the root and leaf of P. africana and P. yohimbe, respectively. Using different concentrations of P. africana extracts, prostate cancer C4-2 cells, a hormonally insensitive subline of LNCaP cells, were treated in a proliferation assay. A concentration dependent inhibition of cell growth in cells treated with P. africana bark and root extracts was present from days 1 through 3 of incubation, with the methanol extract of the bark showing the strongest effect. Compared to other plant parts, leaf extracts were significantly less cytotoxic at the same concentrations. All plant part extracts contained significant amounts of phenolic compounds and pigments with potent antioxidant activity comparable to that of ascorbic acid, in the case of P. africana, demonstrated in vitro cytotoxicity.Item Numerical solutions to paraxial wave equationsMross, Colby PierceIn this thesis, we apply various numerical methods to solve ordinary differential equations and the paraxial wave equation. The numerical methods we applied to solving paraxial wave equation are the 4th order Runge Kutta method, the Crank-Nicolson method, the Leapfrog Crank-Nicolson method, and the splitting spectrum method. The advantage of the explicit RK4 method is the high order accuracy in time. We perform detailed comparison between these numerical methods. The paraxial wave equation is derived from Maxwell's equation and we focus on the case of cubic Kerr nonlinearity presents, which is applied to study optical pulse propagation in nonlinear Kerr media. The Leapfrog Crank-Nicolson method, being an implicit method, is the most cost efficient method and when choosing small step sizes can be the most accurate when applied to paraxial wave equations.Item Magnetic Noise due to Interactions Between Bulk Impurities and Electrons in Nitrogen Vacancy Center DiamondsBarrios, BruceNitrogen vacancy centers (NV) diamonds present great interest as robust atomic-scale magnetic field sensors. One of the serious problems of NV-center diamond devices is electric and magnetic field noise. The noise can be verified by the optically detected magnetic resonance (ODMR) line-broadening; the noise reduce sensitivity of the devices. In this work we theoretically study the magnetic field noise caused by the magnetic dipole-dipole interactions between the bulk impurities of 13C, 14N and the electron in the NV-center. We use the cluster correlation expansion method to calculate the magnetic field fluctuations, and then, obtain the noise spectrum. The noise spectra is greater at lower frequencies but decrease at higher frequencies.Item Improving identification of subtle changes in wide-area sensing through dynamic zoomGreen, Michael AlvinThe past decade has seen an abundance of applications that utilize sensors to collect data. One such example is a gigapixel image, which combines a multitude of high-quality images into a panorama capable of viewing hundreds of acres. The resulting datasets can be quite large, making analysis time consuming and resource intensive. Moreover, coverage of such broad environments can mean numerous sensor feeds to which one must attend. A suitable approach for analysis and sense-making of such data is to focus on "interesting" samples of data, namely regions of interest, or ROI. ROIs are especially useful in wide-area sensing situations that return datasets that are largely similar from one instance to the next, but also possess small differences. Identifying subtle changes is relevant to certain scenarios in surveillance, such as the evidence of human activity. Several ROI detection techniques exist in the research literature. My work focuses on ROI detection tuned to subtle differences for images at varying zoom levels. My thesis consists of developing a method that identifies regions of interest for subtle changes in images. In this pursuit, my contributions will address key questions including the characterization of image information dynamics through introduction of dynamic zoom, the definition and measurement of subtlety, and an approach for scoring and selecting ROIs. This work will provide an automated attention mechanism for zoomed images, but is also applicable to domains include satellite imagery and cyber security.Item Enzyme-assisted aqueous extraction of Njangsa (Ricinidendron heudelotti) seed oilArrey, Immaculate TabeSolvent extraction methods are widely used industrially to obtain oil from plant seeds, mostly due to their high efficiencies (90-98% w/w yield). However, consideration is being given to solvent-free extraction methods due to the growing concern that residual solvent in oil could pose significant health and environmental risks. As such, enzymatic extraction methods are receiving considerable interest in the oil industry due to their high specificity. Certain enzymes such as: hemicellulase, protease, pectinase and amylase are known to hydrolyze and degrade the cell wall of oilseeds, which significantly increases oil yield and quality upon extraction. Therefore, the aim of this study was to explore the effects of these four different enzymes on Njangsa (Ricinodendron heudeulotti) seed. A control without any enzyme was run in tadem. These treatments were compared to solvent-extraction using hexane. The percent yield of the enzyme-assisted extraction (28.37 - 36.0%) were significantly (p < 0.05) higher than that of the control (19.09%) but, lower than the hexane extraction (46.40%). Quality indices of Njangsa seed oil (NSO) such as: acid, peroxide, saponification, thiobarbituric acid, para-anisidine and free fatty acid values of the enzyme-assisted extraction samples were found to be significantly (p < 0.05) lower than the solvent extraction samples. Predominant fatty acids of NSO were alpha-eleostearic acid (α- ESA), linoleic, stearic, and oleic. NSO had a high polyunsaturated fatty acid content. The use of enzymes in Njangsa seed extraction were able to improve the quality parameters of Njangsa oil.Item The study of bacterial communities in catfish (ictalurus punctatus) during storageAccumanno, GinaFish is a lean source of protein and abundant in vitamins and minerals. Unfortunately, fresh fish deteriorates rapidly mainly due to microbial spoilage. With consumers’ health concerns about using harsh chemical preservatives, natural antimicrobials would be a safer, alternative solution to prevent microbial spoilage. Metagenomics refers to investigating microbial communities from foods, environmental samples etc. and understanding how they interact with one another. Bacterial taxonomy, as a whole can be classified using high throughput sequencing platforms. In this study a commercial store-bought catfish and a pond-raised catfish were treated individually with three natural preservatives. From the catfish samples under refrigerated storage, DNA libraries were sequenced on the Illumina MiSeq platform. Of the 3 treatments, N#1 showed the most significant bacteria reduction at the midpoint (99%) in the store-bought fish and in the pond-raised fish in the late phase (>99%). Pseudomonas dominated the other bacteria in early phase for all sample treatments in the store-bought fish but was suppressed by the N#1 in middle phase which allowed for more diversity. In the pond-raised fish, Pseudomonas also dominated other bacteria in the sample treatments for the middle and late phases but never became the dominant bacterial species for the pond-raised N#1 samples which allowed for greater diversity overall. This knowledge can suggest effective natural preservative treatments to extend the shelf-life of fishery products.Item An examination of recreational angling for sharks in Delaware watersJohnson, SymoneRecreational angling targeting prohibited shark species (e.g. Sand Tiger (Carcharias taurus) and Sandbar (Carcharhinus plumbeus) Sharks) has increased in Delaware, raising concerns about the population status of these species. In an attempt to help address these concerns, my thesis had two objectives: to better understand recreational anglers’ perceptions of and interactions with prohibited sharks; and to explore gear modifications that result in minimizing harm to shark species caught during recreational angling. To achieve my first objective, I developed an angler survey with the goals of: 1) improving our understanding of threats to sharks, 2) identifying potential solutions to threats of shark conservation, and 3) improving fisheries management of sharks through reduced injury or mortality. The survey highlighted the need for improved accuracy in species identification and compliancy with best angling practices and/or regulations as threats to shark conservation. My findings suggest that resource managers may modify their approaches to reduce injury or mortality of sharks through increased angler education and training, K-12 education, social media campaigns, and increased enforcement. Building upon this, I examined the efficacy of experimental (blocker) longline gangions compared to control gangions for reducing damage to individual Sand Tiger and Sandbar Sharks during capture events. Over a three year period (2012-2014) comprising of 153 longline sets, I landed 493 Sand Tiger and 240 Sandbar Sharks. Overall catch rates of Sand Tigers (p = 0.024) and Sandbar Sharks (p = 0.013) were reduced on the experimental gangions. Gear type had a marked impact on hooking location (p = 0.003) for Sand Tigers as the overwhelming majority (96.3%) of gut hooked Sand Tiger individuals were encountered on control gangions. The use of blocker gangions shows much promise in minimizing risk of injury for Sand Tigers captured during longline surveys. In the case of Sandbar Sharks, there were no incidents of gut hooking in the entire study suggesting that the risk of injury from gut hooking is minimal for the species. The marked decline in gut hooking rates with Sand Tigers noted with the use of the experimental gangions underscores its potential use as a tool to reduce injury risk and to improve post-release survival prospects. It is well understood that a healthy marine environment provides direct and indirect economic awards and healthy shark populations are a key point in these environments. I hope my efforts to provide insights on angling preferences and practices in Delaware, as well as a potential tool for use in the angling community, will help foster increased recovery prospects for these important species.Item Characterization of strawberry (fragaria ananassa) by genotyping and phenotypingBiswas, AnjuStrawberry is an important fruit crop for its nutritional value and is known to have a higher amount of antioxidants. Consuming strawberries can increase dietary antioxidants. Antioxidants in strawberry can act against cardiovascular diseases, cancer, and other health issues. Recently, use of molecular markers is becoming popular in strawberry breeding programs as well as in genotyping of existing varieties. Genotyping is the process of determining genetic differences among individual plants and can be readily applied to identify genetic diversity among the germplasm. Simple sequence repeat (SSR) markers present in every living organism. Majority of the SSR markers are used for genotyping includes cultivar identification, genetic diversity analysis, taxonomic analysis, marker-assisted breeding, and cloning. It is easier to identify a trait of interest in any genotype if known SSR markers are available. Cultivated strawberries have a wide range of SSR markers available which permits to detect polymorphism of closely related genotypes as the genome of strawberries has been sequenced. In this study, we genotyped thirty-three strawberry accessions utilizing thirty-five SSR markers and phenotyped by observing leaf total antioxidant (TA) content, leaf shape, leaf trichome density and petiole size. DNA extraction, PCR, and SSR analysis were done for genotyping. We identified two distinct genetic groups from those genotypes, one group is alpine (wild or woody) type strawberry and another group is the cultivated type. In this study, we identified 120 alleles with an average of 3.43 alleles per locus. The genetic polymorphism ranged from 0.1461 for the marker ARSFL_9 to 1.6635 for the marker FG1a/b. All thirty-three accessions were grouped into clusters based on the genetic diversity analysis and found that grouping them into three clusters was provided the maximum genetic diversity. The cluster three contained more diverse genotypes among those. Leaf total antioxidant content was measured in Trolox equivalent amounts by colorimetric assays. The highest antioxidant containing genotypes were Earliglow, Wendy, Elan hybrid, Clancy, and Record. Spectrophotometer and high-resolution camera were used for phenotyping. We classified all genotypes into five groups according to the leaf shape and three groups according to the leaf trichome density and leaf petiole size. From the association, the two genotypes named Clancy and Elan hybrid contained more total antioxidant content with high trichome density. Strawberry breeding programs can utilize information from this research during cultivar development and authentication of genotypes.Item Monitoring of vibrio species in oysters crassostrea virginica and seawater of Delaware bay and molecular characterization of vibrio parahaemolyticusAlmuhaideb, EsamABSTRACT Delaware Bay is the prime oystering ground in Delaware. Oysters naturally inhabit marine environments and, as filter-feeding mollusks, they tend to accumulate different microorganisms from seawater during their filtration process. Most of the illnesses caused by the consumption of raw and undercooked oysters are strongly associated with the oysters contaminated with Vibrio spp. Vibrio spp. are Gram-negative pathogenic bacteria from the family Vibrionaceae that negatively impact aquatic systems and human health. This study aimed to identify and differentiate Vibrio spp. in oyster and seawater samples from the Delaware Bay using CHROMagarᵀᴹ Vibrio medium which provides the means for easy differentiation of Vibrio parahaemolyticus, Vibrio vulnificus, Vibrio cholerae, and Vibrio alginolyticus based on the colony color. Pathogenic Vibrio parahaemolyticus was characterized using conventional PCR which was applied for the identification of total and pathogenic V. parahaemolyticus by screening the species-specific tlh gene, and the virulent tdh, trh, toxR, and vpm genes. Vibrio spp. were differentiated and isolated, and total and pathogenic V. parahaemolyticus from oyster and seawater samples were identified. Oysters and seawater samples were collected once a month from June through October 2016, from Bowers Beach, and Lewes, Broadkill in Delaware Bay. A third site, Slaughter Beach, was added to this study from August through October 2016. Physico-chemical water quality parameters recoded on-site during samples collection include water and air temperature, salinity, pH, dissolved oxygen, turbidity, chlorophyll a, depth, conductivity, weather, wind direction, wind speed, and tide. Oyster and seawater samples were serially diluted up to (10⁻⁶), and 100 µL of each dilution from each sample were spread plated on CHROMagarᵀᴹ Vibrio medium. V. parahaemolyticus, V. vulnificus/V. cholerae, and V. alginolyticus colonies were identified based on color development (mauve, green/blue, and colorless, respectively). Average Vibrio spp. in oyster ranged from <10 CFU g-1 (non-detectable) to 2.8×104 CFU g-1, while the average of Vibrio spp. in seawater samples ranged from 1.7×10 CFU mL-1 to 4.47×103 CFU mL-1. More Vibrio colony forming units were observed during the warmer months (June through September). As anticipated, the total colony forming units of Vibrio spp. were proportional in both oyster and seawater samples. The multiple regression model indicated a significant positive relationship between Vibrio spp. and V. parahaemolyticus Log10 CFUs and water temperature, (p < 0.05). The one-way ANOVA analysis showed no statistical significant association between Vibrio spp. Log10 CFUs and the sample type, oysters and seawater (p > 0.05). A total of 165 bacterial isolates of Vibrio parahaemolyticus (mauve colonies) from oyster and seawater samples were examined for the presence of tlh, tdh, trh, toxR, and vpm genetic markers. Only 19% of the samples tested were positive for tdh and 24% were positive for trh while 83%, 65.5%, and 67% of the samples were positive for tlh, toxR, and vpm, respectively. This confirmed the specificity of tlh gene for V. parahaemolyticus species. Screening for tdh and trh genes is not sufficient for the surveillance of pathogenic or potential pathogenic V. parahaemolyticus but the reliability of toxR and vpm as gene markers is notably higher.Item Regulation of gene expression by the CD44-Intracytoplasmic domain (CD44-ICD)Shelton, Alexis S.CD44 is a major cell membrane hyaluronan receptor and cell adhesion glycoprotein. It is involved in multiple cellular processes including cell migration and invasion, apoptosis, stemness and cell proliferation. It exists in a variety of isoforms mainly due to the alternative splicing of ten of its 20 exons and posttranslational modifications. CD44 also undergoes proteolytic cleavages that generate the CD44 intracytoplasmic domain (CD44-ICD). The CD44- ICD is translocated to the nucleus where it can regulate gene expression. The CD44-ICD- dependent regulation of gene expression is likely to be mediated by protein-protein interactions (PPI) with factors of the transcriptional machinery, which makes of the CD44-ICD a transcriptional co-regulator. However, the existence of the CD44-ICD response element (CIRE) and its reported binding to it makes of the CD44-ICD a transcription factor. We hypothesize that the CD44-ICD is a novel transcriptional regulator with properties of a co-regulator and a transcription factor. To test this hypothesis we carried out PPI assays such as proximity ligation assays (PLA) and plate array PPI assays. We also analyzed the expression of genes related with CD44-associated cellular events such as apoptosis, oxidative stress and stemness using proteome profiler assays and transcription factor activation plate arrays. PLA data showed that the CD44- ICD interacts with the transcription factor Runx2 in the nucleus as well as in the cytoplasm. We also found that the CD44-ICD interacts with more transcription factors. The expression of CD44 in MCF-7 cells, which is expected to generate the CD44-ICD, inhibited the expression of Nrf2, caspase 3 and E-cadherin, important genes in oxidative stress, apoptosis and stemness, respectively. The inhibition of Nrf2 in MCF-7/CD44 cells, promoted a higher sensitivity to oxidative stress caused by hydrogen peroxide compared to MCF-7 cells. Altogether, these data iii supports that CD44 can act as a regulator of gene expression and that this regulation is in part via its intracytoplasmic domain once released into the cytoplasm and nucleus. The CD44-ICD appears to be able to act as a co-activator as well as a co-repressor. Because the CD44-ICD size of only 72 residues, the CIRE sequence to which it can bind is unusual. This type of protein- DNA interaction is usually associated with larger DNA-binding proteins such as bona fide transcription factors. The dual capacity of the CD44-ICD to interact with proteins of the transcriptional machinery as well as to interact with its own response element on promoter sequences, might place the CD44-ICD in a novel category of transcriptional regulators.Item The Neuroprotective Effects of Sumo Conjugase, Ubc9, in Dopaminergic Cells and NeuronsWilliams, DionneParkinson’s disease (PD) is characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc) and related to alpha-synuclein mediated protein aggregation. These protein aggregates are known as Lewy bodies. The Small Ubiquitin Modifier (SUMO) is a form of post-translational modification that regulates protein function and stability. Although SUMOylation may increase the solubility of alpha-synuclein, the role of SUMOylation in dopaminergic neurons remains unclear for PD pathology. Our preliminary studies show that the SUMO conjugase, Ubc9, protects rat dopaminergic cells against 1-methyl-4-phenylpyridinium (MPP+) toxicity and prevents the protein degradation of dopamine transporter (DAT) (Cartier et al., manuscript under review). We hypothesize that the overexpression of Ubc9 protects dopaminergic neurons against oxidative stress. For in vitro studies, N27 rat dopaminergic cells overexpressing Ubc9-EGFP showed higher cell viability and lower cytotoxicity against MPP+ induced toxicity, compared to EGFP only cells. In vitro studies include cell viability (MTT) and cytotoxicity assay (LDH), reactive oxygen species (ROS) detection, and mitochondrial respiration, to determine the protective role of Ubc9 in dopaminergic cells against oxidative stress (MPP+). We also established transgenic C57Bl/6 mice overexpressing Ubc9 or wildtype C57Bl/6 mice in the lab. Chronic intraperitoneal injection of the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) has been utilized to induce parkinsonism for both transgenic and wildtype C57BL/6 mice. Using immunhistological staining of tyrosine hydroxylase (TH) as a marker for dopaminergic neurons. We found that the pan-Ubc9 overexpression protected dopaminergic neurons in the striatum and the Substantia Nigra from MPTP-toxicities, compared to wildtype littermate mice. Our study supports that SUMOylation can be a potential therapeutic target to prevent oxidative stress-induced PD pathology. Currently we are assessing the neuroprotective mechanisms of Ubc9-mediated SUMOylation in PD models.Item Thermal charge noise of a near-surface nitrogen vacancy center diamond with a protective layerChrostoski, Philip CA nitrogen vacancy center in diamond has become an interesting topic to investigate with their applications in magnetic field sensors and quantum computing. A major problem in their applications has been the large amounts of noise. Fluctuations in both the electric and magnetic fields give rise to this noise. At room temperature, the electric field has shown to be the largest factor in the noise. We decided to investigate these thermal fluctuations caused by the electric field. The model used is a system consisting of the NV-center with a protective layer on the surface. We examined different surface materials such as; D-glycerol, propylene carbonate, and others to compare with recent experimental data. The fluctuation dissipation theorem was used to obtain the charge noise spectral density. The noise for the liquid protective layers is less than the solid protective layers initially. The liquids show better noise reduction due to their faster relaxation times for their dipole interactions. Both the real and imaginary parts of the permittivity play key roles in effecting the noise of the system.Item Rudimentary syntheses of solution processable polyaniline and graphene oxide materials for energy device applicationsMelton, Omar TalibElectrically conductive polymers (CPs) play a major role in organic electronics and are alternatives to traditional energy and electronic materials. The focus of this research is the rudimentary syntheses of polyaniline (PANI) as a processable and electrically conductive polymer, graphene oxide (GO) and reduced graphene oxide (rGO) materials for energy conversion or storage device. Novel and augmented syntheses are conducted intended for the improvement of processability, conductivity, and development of PANI and GO material film. We have observed that the bulky dopant, dioctylsulfosuccinate sodium salt (DSS), improved the solubility of PANI. The variation of solvent was attempted to increase the electrical conductivity, with o-xylene showing improved dispersion capability over toluene. Additionally, the synthesized PANIs exhibited differences in both film formation and conductivity. GO was produced from a variation of a modified Hummers’ method. This new method incorporated the use of inexpensive commercial materials working toward the synthesis, purification, and development of GO. Bulky commercial grade graphite powder was used in place of the typical graphite flakes. Furthermore, cellulose filter paper was coopted in place of the standard metal sieve. Through effective grinding of graphite, the resultant synthesized material was good quality GO. Afterwards, thermal treatment applied under vacuum successfully reduced GO. The subsequent films fabricated from heat treated GO showed crystalline structure and improved conductivity over other GO materials.Item Germanium silicon tin oxide thin films for uncooled infrared detectorsCardona, JaimeMicrobolometer is a class of infrared detector whose resistance changes when the temperature changes. In this work, we deposited and characterized Germanium Silicon Oxide thin films mixed with Tin (Ge-Si-Sn-O) for uncooled infrared detection. Ge-Sn-O was deposited by co-sputtering of Sn and Ge-Si targets in an Ar+O environment using a radio frequency (RF) and direct current (DC) sputtering system. The electrical and optical properties of the thin films were tested to verify whether Ge-Si-Sn-O could be used as a sensing material in a microbolometer. From this testing, it was shown that with the an atomic composition consisting of Ge0.36Si0.04Sn0.11O0.43 the Ge-Si-Sn-O alloy could have a temperature coefficient of resistance (TCR) greater than -3.5 %/K, optical band gap of around 1 eV, and noise value of 300 μV/√Hz at 10Hz. With these values, besides the slightly high noise value, it has been determined that Ge-Si-Sn-O alloy is a viable candidate for use in microbolometer development.Item Validating the role of Pcl6 in the cell cycle in yeast (Saccharomyces cerevisiae)Cruz, VanessaThe cell cycle consists of a set of processes that result in the duplication of cellular constituents. Cyclin dependent kinases (Cdks) ensure successful progression of cells through the cell cycle. Cdk activation requires cyclin binding and phosphorylation of its appropriate substrate to tightly regulate cell cycle progression. There are six known Cdks in yeast (Saccharomyces cerevisiae); Cdc28, Kin28, Srb10, Ctk1, Bur1 and Pho85. Cdc28 is the only essential Cdk due to its crucial role in cell cycle progression. The remaining Cdks contribute to cell cycle progression through regulation of gene expression and cellular metabolism. The cyclin partners for Pho85 includes Pcl6. Knowledge about Pcl6 is limited. The goal of this project is explore and validate the role of Pcl6 in yeast cell biology. Based on literature review, we hypothesized that Pcl6 is regulated by components of the Nucleotide Excision Repair (NER) complex in yeast. The NER pathway in yeast is known to repair endogenous DNA damage in yeast cells. Our results confirm our hypothesis. Components of the NER pathway regulate the stability of Pcl6 in our NER mutant strains. Our studies also explore the sensitivity of exogenous DNA damage on the viability of the NER mutants. Our results show cell sensitivity to exogenous DNA damage by 4-Nitroquinoline 1-Oxide, Hydroxyurea, Hydrogen Peroxide, Nocodazole and Methyl-Methane Sulfonate. Future studies will determine the effects of endogenous and exogenous DNA damage on Pcl6 protein level.Item Stellate macroporous silica nanospheres in bio-macromolecules encapsulation and deliveryChi, Hao-HsinThis project focused on using mesoporous silica as a solid support to encapsulate enzymes for operating a highly economic, and recyclable biomass processing system. The main objective is to turn non-food biomass sources into food products. Enzymes are macromolecules with the structural backbone of proteins or ribonucleic acid sequences (RNAs) which work as catalysts in living organisms. Enzymes have the advantage of being the least contaminating catalyst due to normal catalyst might generate toxic by-product, and preferable to organic and inorganic catalysts, especially when used for product related to human used, which require biocompatibility of final product. However, there are several disadvantages in enzyme utilization. Their fabrication is time-consuming and requires elaborated molecular biology processes. Most of the enzymes need well-defined reaction conditions to be functional and operate at high yield. Unfortunately, although they are reusable as normal catalysts, it proves difficult to extract or reuse the enzymes from a reaction. Also, enzyme molecules are easily degradable and demand proper storage. To overcome some of the disadvantages, especially regarding stability to degradation, recovery, and reusability, immobilization of enzyme on solid support has become a thriving methodology. In recent years, mesoporous silica nanomaterials(MSN) have been at the forefront of enzyme immobilization given their extensive surface area, which provides capability to increase enzyme loading and for their demonstrate ability to protect enzyme from degradation, thus enabling high recyclability. Mesoporous silica is biocompatible and has already been used for several applications included. Catalysis, drug delivery, and Bio-imaging. Previously published research utilized mesoporous silica to deliver drugs, DNAs, RNAs or encapsulate single enzyme. The objective of this research is completed to develop a new porous silica platform that is unique in its porosity structure and develop it into a dual-enzyme platform with the scope of demonstrating a multi-reaction bio nanocatalyst. In regard to the further applications, the stellate MSN can be used as drug delivery or become a package of the biomacromolecule delivery system kit.Item A frontotemporal dementia and motor neuron disease mouse model of tdp-43 proteinopathyHarmon, AshleyMotor neuron disease (MND), of which amyotrophic lateral sclerosis (ALS) is one example is a neurological disorder that involves the progressive loss of motor neurons. The death of these motor neurons leads to a loss of voluntary muscle control that can affect speaking, walking, breathing, and swallowing leading eventually to death. There is currently no cure for ALS therefore understanding mechanisms associated with the progression of this disease is crucial to developing a treatment. Transactive response DNA binding protein of 43kda (TDP-43) functions as a heterogeneous nuclear ribonucleoprotein (hnRNP) and is the major pathological protein in frontotemporal dementia (FTD, 50%) and sporadic ALS (95%). Mutations in TDP-43 account for ~5% of familial ALS cases. In a subset of cases with TDP-43 proteinopathy, patients clinically display both frontotemporal temporal dementia and motor deficits (FTD-MND). We have characterized an age-dependent decrease in motor function associated with pathological changes in mice selectively driving TDP-43 expression in the spinal cord and brain using a neuronal-specific (Prion) driver. Expression of a nuclear localization defective (NLS) TDP-43 mutant in spinal cord and brain showed severe motor deficit and significant changes in anxiety in 16-18 month old mice. Although there was a relatively late onset of symptoms compared to the human disease, that may be related to the low level of exogenous TDP-43 expression, these models may provide a better understanding of TDP-43 proteinopathies leading to the development of therapeutics to target these devastating diseases.Item Behavioral consequences of point mutations in the vesicular acetylcholine transporterWhite, DanielThe neurotransmitter acetylcholine (ACh) is involved in critical organismal functions as locomotion, learning and memory. Therefore, alterations in this neurotransmitter system is a key underlying factor in movement and cognitive deficits. The vesicular acetylcholine transporter (VAChT) mediates the packaging of ACh into synaptic vesicles for exocytotic release. Mutations in this protein ultimately diminish locomotion whereas complete loss of function of VAChT is fatal. The direct role of altered acetylcholine release and its association with impairment or enhancement of cognitive functions is still not fully understood. We hypothesize that point mutations in VAChT causes age-related deficits in cholinergic-mediated behaviors such as locomotion, learning and memory. Using Drosophila melanogaster as a model system, we have generated several mutations within VAChT and observed its effect on survivability, longevity and locomotive behavior. Here we report that VAChT point mutants causes defects in locomotion ability and an allele dependent deficit in lifespan. These results demonstrate that cholinergic release is important for the regulation of behavioral performance in Drosophila. In future studies, we will test methodologies to effectively rescue these deficits with implications for intervention strategies to treat cholinergic deprived disorders such as Alzheimer’s disease. Future studies will turn to investigating the effects of VAChT overexpression to determine whether the deficits seen in the Vacht mutants can be decreased or reversed.
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