Digital Commons @ the Georgia Academy of Science
Not a member yet
1290 research outputs found
Sort by
EXPLORING NOVEL REACTIVITY FOR ENGINEERED MYOGLOBINBIOCATALYST: [2,3] SIGMATROPIC REARRANGEMENT OF ALLYLIC ALCOHOLS
No full textBiocatalysis is a green, sustainable process in which enzymes, whole-cells or other biological catalysts perform a required synthetic transformation in a highly efficient manner. Recently, the heme protein myoglobin (Mb) has been emerged as a robust biocatalyst. The engineered versions of Mb biocatalyst have shown to perform non-native chemical transformations such as cyclopropanation of activated and unactivated alkenes, hetero-atom insertion (S-H, N-H) reactions etc. in very high yields and in excellent selectivity. Here, we explore the reactivity of engineered Mb variants toward the [2,3] sigmatropic rearrangement of allylic acetals and thioketals to provide a simple, environmentally friendly and sustainable route to synthetically useful multifunctional organic compounds. With the above goal in mind, a feasibility study was performed using acrolein dimethyl acetal and ethyl diazoacetate (EDA) in presence of engineered Mb catalyst, Mb H64V V68A. Along with preforming these reactions under anaerobic, semi-aerobic, and aerobic conditions, this study incorporates additionally diverse experimental and controlled variables such as concentrations of the substrate and enzyme, temperature, pH, time trials, and substrate ratios. Our hope is to explore the prime conditions for this engineered myoglobin biocatalyst and determine conditions that this enzyme is able to function optimally in. Gas chromatography (GC) and Gas chromatography-Mass spectrometry (GC-MS) were used to quantify the biocatalysis reaction yields, percent conversions, and reaction rates. Nuclear magnetic resonance spectroscopy (NMR) was used to characterize the standard products and the products obtained from enzyme reactions
COMPARISON OF HOMOGENEOUS CATALYSTS FOR THE CONVERSION OF BIOMASS TO FORMIC ACID**
No full textCellulose is a biopolymer that is present in all plant biomass, serving as the major component of cell walls. Due to the abundance of this polymer, chemists have sought various ways to transform cellulose and glucose, its monomer, into renewable feedstock chemicals. One target molecule is formic acid (HCO2H), the smallest carboxylic acid, which can be used in a wide range of applications, including further conversion into components of syngas (H2 and CO). Previous conversions of cellulose or glucose into formic acid have required high pressures (~30 atm) and temperatures (160 °C). For this research, we studied three different catalysts: sodium metavanadate (NaVO3), iron (III) chloride (FeCl3), and tris-(2,2’-bipyridyl)iron(II) chloride ([Fe(bpy)3]Cl2) for the conversion of cellulose and glucose to formic acid under reduced temperatures and pressures
USING GAMESS TO DETERMINE TRANSITION MOMENTS**
No full textThe installation and use of GAMESS (General Atomic and Molecular Electronic Structure System) a general ab initio quantum computational program is discussed. GAMESS is a free computational package that is used to evaluate the transition dipole moments of several conjugated organic compounds, including 1,4-diphenyl-1,3-butadiene and 1,6-diphenyl-1,3,5-hexatriene . The computational results are compared to results from linear dichroism analysis and to literature values where available
THE IMPACT OF FIRE ON SOIL CHARACTERISTICS IN THE MARITIME FORESTS ON SAPELO ISLAND, GA
No full textHuman activities have drastically altered fire regimes in countless ecosystems by suppressing and/or effectuating fires. In the past, management strategies were formulated to eliminate the occurrence of fire altogether. As we have become more aware of the benefits of fires such as reducing the amount of fuel build-up, the recycling of nutrients for healthier plant communities, and the promotion of biodiversity, prescribed burns are now considered an integral part of forest management. Sapelo Island which is located off the coast of Georgia experiences both prescribed and natural fires. The goal of this study was to investigate the impact of no fire, prescribed fire, and natural fire on soil characteristics within an ecosystem. We hypothesized that soil samples collected from areas impacted by the high-intensity wildfires would have poor nutrient qualities for sustaining healthy vegetation, especially when compared with soils from the prescribed fire area. Prescribed burns are conducted between December-April on the Island and natural fires typically occur during the summer (May-July). Therefore, samples were collected between May-October of 2019. Within the areas of interest, four sites were chosen for sampling based on their proximity to areas that experienced prescribed or natural fires. Horizontal transects were established and sample plots placed along each one at equal intervals for a total of 15 sample plots per transect. In each plot, a soil sample was collected by taking from multiple locations within the sampling plot using a soil auger. We measured soil quality by determining soil pH, and extractable phosphorus, potassium, calcium, magnesium, zinc, manganese, copper, boron, and sodium (all measured in ppm). Understanding soil texture, cation-exchange, and nutrient changes in fire impacted areas will help managers further understand fire dynamics on the island and inform management strategies
USING IRIDOVIRUS CORE GENES TO TEST KNOWN PHYLOGENETIC RELATIONSHIPS BETWEEN AMBYSTOMA TIGRINUM VIRUS STRAINS FROM THE WESTERN USA**
No full textRanaviruses are emerging infections in ectothermic vertebrates. They are known to affect over 145 species of amphibians globally and are members of the Iridoviridae. Iridoviruses have 26 core genes that are conserved between genera of the viruses. In this study we examined five of the 26 core iridovirus genes in 15 strains of Ambystoma tigrunum virus (ATV) from the western USA, which are known to have local/geographical variation in several other genes which are not in the core genes of iridoviruses. Here we examined the Hypothetical Protein-Clostridium tenani (Open Reading Frame, ORF 11L), the Immediate Early Protein ICP-4 (ORF 13L), Myristilated Membrane Protein A (ORF 51L), Myristilated Membrane Protein B (ORF 1L) and Transcription Elongation Factor TIIS (ORF 24L) as potential alternatives to non-core genes for phylogenetic reconstruction of closely related strains. Sequence data obtained from GenBank and analyzed using a MAFTT server and MEGA software, will be compared visually for homology and utility as alternate genes for discerning local adaptation in these ATV strains. Based on initial data from other core genes, we expect to find that these are too highly homologous to be informative over small geographical scales within the same genus of ranaviruses
EFFECTS OF QUERCETIN AND RESVERATROL ON AHR ACTIVATION IN MOUSE HEPATOCYTES EXPOSED TO BEEF CHAR**
No full textStudies have shown that the consumption of meat, particularly charred beef, causes an increased risk of cancer. When beef is grilled at high temperatures, carcinogens such as heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs) are produced. These compounds can bind to and activate the aryl hydrocarbon receptor (AhR), leading to their metabolic activation into DNA-adduct-forming carcinogens. In recent studies, stilbenoids, such as resveratrol, and bioflavonoids, such as quercetin, have been shown inhibit the activation of the AhR, thus preventing the PAHs from activating the receptor. These chemicals are found in a variety of edible vascular plants, including those that produce fruits, vegetable, nuts, seeds, herbs, spices, flowers, tea and red wine. In our studies, we will treat Hepa1.1 mouse hepatocytes with solutions of charred beef extract in either phosphate-buffered saline or ethanol to confirm transcriptional upregulation of an AhR-mediated cyp1a1 luciferase reporter gene. We will further investigate whether co-treatment with resveratrol or quercetin can block activation of the AhR in hepatocytes exposed to extracts of charred beef
MORINGA PLANTS AS EXPOSURE PATHWAYS FOR HEAVY METALS IN KABWE, ZAMBIA**
No full textNine decades of lead mining at the Broken Hill Mine in Kabwe, Zambia subsequently polluting the surrounding neighborhoods. This study is being carried out to assess the potential health risks of exposure to heavy metals via consumption of medicinal Moringa oleifera. While the tree could be medically beneficial to residents in contaminated areas, its ability to hyperaccumulate heavy metals could cause the tree to act as an additional exposure pathway to metals for people living in these areas. In addition, this study will examine the relationship between lead concentration in soils to the amount taken up by the moringa trees. Field samples were collected to analyze metal content of various parts of the tree and the surrounding soils. Moringa trees were also grown in lab to further determine the degree of heavy metal accumulation in different parts of the tree, in a controlled environment. The effect of mycorrhizae on metal uptake by moringa will also explored
An Eight-Year Photometric Study of the Seyfert 1 Galaxy NGC 5548 **
No full textWe present multi-wavelength continuum light curves spanning the period 2012 to 2020 for the Seyfert 1 galaxy NGC 5548. CCD observations in the B, V, R, and I photometric bands (using Johnson/Cousins or Bessel filters) were made with the telescopes operated by the Southeastern Association for Research in Astronomy (SARA) in Arizona, in Chile, and on the island of La Palma. Our observations show that NGC 5548 brightened by one-half to one magnitude (depending upon the filter) during the period 2012 to 2014, followed by a three-year period of dimming. During 2019 the galaxy exhibited a period of rapid brightening. The data show a correlation between brightness (V) and color (V-I), though with significant scatter. These observations will contribute to ongoing reverberation mapping studies of NGC 5548, with the goal of determining the mass of its central back hole (estimated at 5.3±1.7×107 solar masses) and the geometry of the surrounding gaseous regions
Hamiltonian Analysis of integrable point vortices in a circular domain
No full textUsing Hamiltonian methods, we analyze the motion of point vortices in a circular domain. We summarize the case with n =1 vortex and focus mainly on discussing the collapse of, and equilibrium solutions for, n=2 vortices. We also discuss results for n=3, 4, and 5 vortices, and with time permitting we may present additional results including quasi-periodic solutions and choreographic solutions
Viscosity of a Crowding Medium Obtained Through Optical Trapping**
No full textThe dynamic viscoelasticity a cellular medium is mainly due to the crowding of a large number of interacting and non-interacting proteins. Our research presents how the viscosity of a medium is altered in the presence of globular proteins. Optical trapping is the experimental technique that we used. Optical trapping is a process of using a laser directed through several lenses and focused into our sample which is filled with beads. When the laser interacts with a bead it uses the momentum of light to create the equivalent of a potential well which holds the bead within a small area allowing us to study the effects, much like that of a spring. Using the variance of the bead’s position found using a Position Sensing Diode, we can find the stiffness of this ‘spring’ that holds the bead within the laser by using the Equipartition Theory. This stiffness leads us to the viscosity which we verify using a second method known as the Passive power-spectrum technique. This technique uses a Fourier transformation of the position data to convert to a power spectrum, fitting this with the Lorentzian and finding the corner frequency will give us the stiffness of the trap, which we compare against the previous method to confirm our findings. We used a 980 nm infrared laser and Nikon inverted microscope to develop a synthetic approach to calculate the viscosity of a medium. This approach has enabled us to calculate the viscosity of several water and glycerol concentrations. The method has been extended to investigate the viscoelasticity of the medium with various concentrations of globular Polyethylene glycol proteins