Each year, UROC students produce abstracts of their summer research projects. Click the program name to see student abstracts from 2014.
Here is a small sampling:
Elmer Zapata-Mercado, Summer Research Institute
Home institution: University of Puerto Rico, Mayaguez Campus
Mentor: Dr. Carig Aspinwall
Title: Evaluation of Monomer Chain Lengths for Stabilization of Black Lipid Membranes via Polyner Scaffolding
Abstract: Biosensors are used for rapid screening of biologically active compounds in the blood and for rapid diagnosis of diseases. We are developing next generation biomimetic sensing technologies based on Black Lipid Membranes (BLMs), a synthetic mimic of the cell membrane environment. Though BLMs provide a useful medium to incorporate membrane proteins in sensors, they are inherently unstable and typically rupture in < 4 h. Thus, there is an urgent need to improve BLM stability to realize biomimetic sensors. To overcome this problem, we doped BLMs with either glycidyl methacrylate (GMA) or hexyl methacrylate (HMA) and the cross-linker ethylene glycol dimethacrylate (EGDMA) and polymerized using UV radiation to evaluate the influence on BLM stability. The conductance of GMA-doped BLMs decreased by approximately 50% after polymerization and the electrical stability, measured as the potential at which the BLM breaks down, increased by > 5 – fold suggesting that the stability of BLMs is improved. For HMA-doped BLMs there was no significant change in the electrical stability suggesting that a polymer scaffold consisting of HMA and EGDMA does not improve the stability of BLMs. To investigate the effect of monomer doped BLM on ion-channel activity, α-hemolysin, a pore forming bacterial toxin, was reconstituted in the GMA-doped BLMs. The conductance of the ion channel (≈0.8 nS) was maintained before and after BLM polymerization. This study finds that doping BLMs with GMA/EGDMA dramatically increased the electrical stability, suggesting that this could be utilized to increase BLM longevity for biosensor development.
Jamie Hernandez, Minority Health Disparities
Home institution: University of Arizona
Mentor: Dr. Jonathan P Vande Geest
Title: Non-Synthetic Electrospun Scaffold for a Tissue-Engineered Vascular Graft to Model Porcine Coronary Arteries
Abstract: Coronary heart disease is a leading cause of death in the United States, causing an increase in demand for the development of therapeutic biocompatible vascular grafts as a possible treatment. Experiments were aimed to propose the feasibility of modeling the properties of porcine coronary arteries using an electrospun cell-seeded gelatin and fibrinogen scaffold. Constructs were fabricated by electrospinning a gelatin and fibrinogen solution at various rotational speeds, translational speeds, and crosslinking times. Mechanical properties of each sample were tested using a microbiaxial optomechanical tensile testing device which simultaneously stretched the sample in a the axial and hoop directions (the latter in response to an increase in intraluminal pressure). Porcine aortic smooth muscle cells (PSMCs) were cultured on the constructs in a custom-made bioreactor designed to stimulate the sample laterally while simultaneously allowing culture media to flow through and around the construct with an aim to mimic physiological conditions. Results from mechanical tests revealed that the biopolymer constructs are less rigid and more compliant than a previously tested porcine coronary artery. Fluorescent imaging of seeded constructs indicated the ability of PSMCs to migrate within the scaffold. Current results suggest that it may be possible to create compliance-matched vascular grafts using various fabrication parameters, with future studies focused on the ability for PSMCs to remodel the construct.
Lauren Edwards, Maximizing Access to Research Careers
Home institution: University of Arizona
Mentor: Dr. Mary Alt
Title: Parental Attention Ratings of Children With and Without Specific Language Impairment
Abstract: Specific Language Impairment (SLI) is a common developmental language disorder that is typified by a deficit in language skills that is not attributed to any other developmental deficiencies. SLI has a high rate of co-morbidity with Attention Deficit Hyperactivity Disorder (ADHD) and both disorders have affected males more than females. Research suggests a link between SLI and issues with attention, so our study focused on the measurement of parental ratings of attention. The research questions were: 1) do children with SLI have higher parental ratings of attentional issues than children without SLI?; 2) do males have higher parental ratings of attentional issues than females? It was hypothesized children with SLI would have higher ratings than typically developing (TD) children and that males would have higher ratings than females in both groups. The parents of the participants filled out the ADHD Rating Scale-IV Home Version and a POWWER Parent Questionnaire about their child. Both forms were quantified and summed together to provide each child with an ‘ADHD Score.’ Results showed the parental ratings of children with SLI were equivalent to those for TD children and males were found to have equivalent ratings to females. However, differences emerged within groups. TD males had higher ratings than TD females, but both sexes had equivalent scores in the SLI group. This could be a reflection of higher comorbidity of attentional issues and SLI or a manifestation of parents interpreting language issues as attentional issues in girls with SLI.
Scott Tan, Integrated Optics for Undergraduate Native Americans
Home institution: Pomona College
Mentor: Dr. Palash Gangopadhyay
Title: Fabrication of Three-dimensional Gridlocked Hierarchical Nanostructured Carbon Electrodes Using Graphene and Magnetic Field Aligned Single-Walled Carbon Nanotubes and their Applications as Supercapacitor Electrodes
Abstract: Effective and low-cost energy storage devices are the key focus of extensive research efforts dedicated towards the development of a more sustainable future. Supercapacitors are unique devices that store energy with many advantages over regular rechargeable batteries. In this project we focused on optimizing a three-dimensional gridlocked hierarchical nanostructured design for carbon electrodes using graphene and magnetic field aligned carbon nanotubes. The highly porous structure, in combination with enhanced networks of conductive paths in the electrode, is expected to increase active surface area of the electrode by many-fold, thereby increasing its performance.
Carbon slurry composed of activated charcoal, polyvinylidene fluoride, graphene, and single-walled carbon nanotubes was dispersed in dimethylformamide and coated upon carbon coated copper foil. Samples were aligned within a magnetic field and dimethylformamide was evaporated to gridlock the electrode nanostructure. Fabricated electrodes were assembled into supercapacitor devices. Performance was tested and evaluated using cyclic voltammetry and galvanostatic charge-discharge measurements.
Results confirm that fabricated electrodes with aligned carbon nanotubes possess higher capacitance compared to those without magnetic alignment. Analysis of data shows specific capacitance as high as 67.1 F/g. Magnetic field alignment enhances specific capacitance by 259%, specific areal capacitance by 155%, Coulomb efficiency by 104%, peak energy density by 163%, and power density by 102% .
When graphene and carbon nanotubes are aligned by a magnetic field, the electrolyte in a supercapacitor is able to access an increased amount of surface area on the electrodes, thereby increasing its performance. Further research may be done to optimize electrode compositions.
Claudia Castro, Student Affairs Research Program
Home institution: University of Arizona|
Mentor: Dr. Ravishankar Palanivelu
Title: Sub-cellular Localization of Lorelei Protein in Arabidopsis Thaliana Reproduction
Abstract: In angiosperm reproduction, the pollen grain forms a pollen tube and extends through the transmitting tract to reach the female gametophyte, where it releases two sperm cells; one fuses with the egg cell giving rise to the embryo, and the other fuses with the central cell giving rise to the endosperm. This completes double fertilization and marks the initiation of seed development. In Arabidopsis thaliana LORELEI (LRE) mutant, most female gametophytes fail to induce pollen growth arrest and remain unfertilized. LORELEI encodes a putative glycophosphatidylinositol (GPI)-anchored membrane protein and is hypothesized to localize in the plasma membrane of synergid cells of the female gametophyte. This class of protein is secreted into the ER, where the GPI anchor is attached to the protein, and ultimately localizes to the plasma membrane. We showed that a wild-type LRE fused to YFP reporter gene (LRE-cYFP) is functional and localizes to the membrane-rich filiform apparatus (FA) of the synergid cells. We used this construct to investigate if predicted secretion signal, GPI attachment signal, and ω-sites are required for localization in the FA of the synergid cells by deleting the conserved domains, transforming them into lre/ lre null mutant, and determining subcellular localization of mutant proteins using confocal microscopy. Loss of signal sequence (LRE(ΔSS)-cYFP) resulted in no cYFP expression, indicating that secretion into ER is critical for LRE expression. Loss of GPI attachment signal and ω-sites affected the localization of LRE in the FA, pointing the role of GPI anchor in subcellular localization of LRE.
David Duron, UROC-PREP
Home institution: University of Arizona|
Mentor: Dr. Wufila Gronenberg
Title: Effects of Visual Occlusion on Metabolic Rates in the Bumble Bee Brain (Apildae: Bombus Impatiens)
Abstract: Sensory deprivation can lead to a reduction in the size of the affected brain regions. Here we test the hypothesis that deprivation may also affect the metabolic activity of the respective brain regions using the metabolic mapping tool of Cytochrome Oxidase (CO) staining. By occluding the vision of one eye we predict the CO concentrations to decrease in the corresponding optic lobes with possible changes in the calyces as well. The staining process used involves a solution of diaminobenzidine (DAB) and cytochrome c to produce a stain with CO that can be measured using 2D image software. Due to technical problems we only had a small sample size, but overall this preliminary study seems to confirm our hypothesis and provides an adequate source to benefit future experiments with similar objectives.