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Articles 91 - 114 of 114
Full-Text Articles in Physical Sciences and Mathematics
Exploring A Ring-Closing Metathesis Approach To The Archazolids, Brianne R. King
Exploring A Ring-Closing Metathesis Approach To The Archazolids, Brianne R. King
WWU Graduate School Collection
The archazolids are a complex family of natural products with distinct structural features. Inspired by these unique structural characteristics, our group sought to synthesize an analogue of this family, dihydroarchazolid B. We were encouraged to synthesize this analogue due to its high potential to be a potent cytotoxic agent against the vacuolar-type ATPases (V-ATPases) and because it is a simpler analogue than the parent natural products from a synthetic perspective. Within this work, a ring-closing metathesis (RCM) approach was explored in depth towards the completion of our target. From these efforts, a metathesis deactivating stereotriad was uncovered in a key …
Synthetic Studies On Guaipyridine Alkaloids, Patrick M. M. (Patrick Michael Mcphee) Shelton
Synthetic Studies On Guaipyridine Alkaloids, Patrick M. M. (Patrick Michael Mcphee) Shelton
WWU Graduate School Collection
The guaipyridines are a class of naturally occurring alkaloids isolated from plants native to the Pacific Islands and Southeast Asia. One member of this family, cananodine, has displayed potent in vitro cytotoxic effects against two different types of hepatocellular carcinoma cell lines. More recently discovered guaipyridine compounds, rupestines A-M, share structural similarities to cananodine and might possess similar anti-cancer properties. The potential medical benefits and the rare and interesting structure of the guaipyridines make them desirable and challenging synthetic targets. Two distinct synthetic routes were developed to access the guaipyridine core, and in doing so the total synthesis of cananodine …
Deoxygenation Properties Of Ru-Based Phosphide Catalysts, Bo Carrillo
Deoxygenation Properties Of Ru-Based Phosphide Catalysts, Bo Carrillo
WWU Graduate School Collection
Bio-oil derived from fast pyrolysis of bio-mass is becoming a more viable option for addressing the growing demand for oil while being more environmentally friendly than fossil fuels. However, bio-oils have poor chemical stability and high acidity due to their high oxygen content. Metal phosphides such as ruthenium phosphide (Ru2P) have been investigated by the Bussell group to catalytically upgrade compounds contained in bio-oil, but further optimization is required before their commercial viability can be accessed. In current research, less expensive, more abundant metals (Co or Ni) are being used to replace some of the ruthenium, which is both expensive …
Synthesis And Reactivity Of Pyridinediimine Iron Complexes: For The Breakdown Of Carbon Dioxide, Zachary Thammavongsy
Synthesis And Reactivity Of Pyridinediimine Iron Complexes: For The Breakdown Of Carbon Dioxide, Zachary Thammavongsy
WWU Graduate School Collection
The increase of greenhouse gases in our atmosphere, particularly carbon dioxide (CO2), has been recognized by the scientific, industrial, and political communities. The increase in CO2 concentration has been connected to negative effects on our environment (global warming). Despite the negative associations of CO2, chemists can synthesize useful organic products and fuel from it. Ideally, the two electron reduction of CO2 to CO can provide one of the two products of synthesis gas (CO and H2), which is used in the Fischer-Tropsch process to produce diesel fuel. This thesis aims to convert CO2 to CO, using a cheap and abundant …
Synthesis Of Alignable Fluorophores For Use In Luminescent Solar Concentrators, Willie E. Benjamin
Synthesis Of Alignable Fluorophores For Use In Luminescent Solar Concentrators, Willie E. Benjamin
WWU Graduate School Collection
Luminescent Solar Concentrators (LSCs) collect and concentrate sunlight for use in solar power generation. First proposed over 30 years ago, LSCs are simple devices consisting of a planar waveguide coated or impregnated with a fluorophore. Sunlight absorbed by the fluorophore, reemitted into the waveguide, and concentrated at the edges of the collector. The most substantial problem with previous iterations of LSC technology is that they suffer from escape cone losses (photons lost through the top and bottom of the waveguide) that limited their size and efficiency. In this study, the reduction in escape cone losses was studied through alignment of …
¹⁵N Heteronuclear Single Quantum Coherence Backbone Assignment Of Cyanomet Isoform Sperm Whale Myoglobin And Permutant, James M. (James Morgan) Hall
¹⁵N Heteronuclear Single Quantum Coherence Backbone Assignment Of Cyanomet Isoform Sperm Whale Myoglobin And Permutant, James M. (James Morgan) Hall
WWU Graduate School Collection
The relationship between backbone dynamics and stability in circularly permuted globins is not well understood. HGL16 is a circular permutant of sperm whale myoglobin (sw Mb) in which the amino and carboxyl termini have been linked by 16 amino acids, (GlyGlyGlySer)4. New termini have been generated between the G and H helices. This permutant was shown to be 5.2 kcal/mol less stable than the wild-type protein. Backbone dynamic studies of permuted globins via 15N Heteronuclear Single Quantum Coherence (NHSQC) nuclear magnetic resonance (NMR) experiments may help achieve a better understanding to the observed stability changes observed. The assignments of both …
Structural And Functional Characterization Of Villin Domain 6 And Supervillin N-Terminal Fragments, Stanislav Fedetchkine
Structural And Functional Characterization Of Villin Domain 6 And Supervillin N-Terminal Fragments, Stanislav Fedetchkine
WWU Graduate School Collection
The protein villin is a member of the gelsolin superfamily, and regulates cytoskeleton formation in the brush border at the apical end of epithelial cells. The six villin domains (V1-V6) form which contain a Ca²+ -dependent actin-binding site associated with the V1-V3 fragment. The six villin domains are homologous to gelsolin and have ~50% sequence identity. In the absence of calcium, gelsolin adopts a compact, inactive conformation stabilized by a 12-residue C-terminal helix. This helix locks domains G2 and G6 as a "latch" in low calcium and releases at higher calcium levels. Tyrosine phosphorylation, phosphatidylinositol 4,5-bisphosphate (PIP2) and calcium concentration …
Development Of Surface-Enhanced Raman Based Sensors, Elizabeth C. (Elizabeth Cecilia) Wellner
Development Of Surface-Enhanced Raman Based Sensors, Elizabeth C. (Elizabeth Cecilia) Wellner
WWU Graduate School Collection
While the medical field incorporates various imaging methods for diagnosis and treatment, there is a need for continual development of real-time in vivo imaging techniques in this field. A surface-enhanced Raman scattering (SERS) based fiber optic sensor is reported. An optical fiber was coated in gold nanoparticles, capable of Raman scattering. SERS active molecules were adsorbed onto the gold nanoparticle film, and SERS spectra obtained. Using 4-mercaptopyridine as a SERS reporter molecule, the chemical environment surrounding the probe was determined by the analysis of the pH sensitive SERS spectra. The methods of preparation and characterization of the SERS-based fiber sensors …
Globin Engineering Studies: Optimizing The Designs Of Circularly Permuted Myoglobin And Single-Chain Hemoglobin, Jamie M. (Jamie Marie) Apperson
Globin Engineering Studies: Optimizing The Designs Of Circularly Permuted Myoglobin And Single-Chain Hemoglobin, Jamie M. (Jamie Marie) Apperson
WWU Graduate School Collection
We are working to produce a stable and effective hemoglobin-based oxygen carrier (HBOC) for critical care. Mammalian myoglobins are good model systems for the protein engineering of human hemoglobin, and in the current work, our aim is to generate a circularly permuted myoglobin with increased thermodynamic stability compared to previous permuteins characterized by our lab. Our initial permuted myoglobin, HGL16, includes a 16-residue Gly-Ser linker (SGGG)4 between the A and H helices in sperm whale myoglobin (swMb). Although HGL16 was shown to fold and function like wild-type swMb, its stability was reduced significantly. In the current work, computational design of …
Silk Fibroin-Based Conducting Polymer Composite Electrodes And Their Use As Electromechanical Actuators, Isabella S. Romero
Silk Fibroin-Based Conducting Polymer Composite Electrodes And Their Use As Electromechanical Actuators, Isabella S. Romero
WWU Graduate School Collection
In order to produce conductive, biocompatible and mechanically robust materials for use in bioelectrical applications, we have developed a new strategy to selectively incorporate poly(pyrrole) (Ppy) into constructs made from silk fibroin. Here, we demonstrate that covalent attachment of negatively charged, hydrophilic sulfonic acid groups to the silk protein can selectively promote pyrrole absorption and polymerization within the modified films to form a conductive, interpenetrating network of Ppy and silk that is incapable of delamination. To further increase the conductivity and long-term stability of the Ppy network, a variety of small molecule sulfonic acid dopants were utilized and the properties …
Diastereoselective Intramolecular Carbonyl Hydrosilation For Complex Polyketide Synthesis, Casey R. Medina
Diastereoselective Intramolecular Carbonyl Hydrosilation For Complex Polyketide Synthesis, Casey R. Medina
WWU Graduate School Collection
It has been found that β-hydroxyketone compounds can be reduced to the corresponding 1,3-diol through an intramolecular carbonyl hydrosilation. Furthermore, because this hydrosilation proceeds through a cyclic 6-membered ring transition state, this reduction can be performed diastereoselectively by placing a stereocenter on the 6-membered ring transition state. Prior to further investigations into this diastereoselective intramolecular carbonyl hydrosilation, a streamlined synthesis of β-hydroxyketone compounds has been developed. This new synthesis features an enone diboration/oxidation sequence found to be successful on a broad scope of enones in high yields. Further studies have shown that placing a stereocenter outside of the transition state …
Structural And Functional Characterization Of A Permuted Hemoglobin, Michael P. (Michael Patrick) Murphy
Structural And Functional Characterization Of A Permuted Hemoglobin, Michael P. (Michael Patrick) Murphy
WWU Graduate School Collection
The tetrameric composition of human hemoglobin complicates protein engineering efforts that are required to improve its potential as an oxygen-carrying therapeutic. In our research to design a single-chain version of the hemoglobin molecule (scHb), we have co-expressed a circularly permuted human β-globin (cp-β) with human α-globin. At micromolar concentrations, the purified recombinant globins appear to associate to form an α-cpβ heterodimer in solution rather than the expected α2-cpβ2 heterotetramer. Compared to recombinant human hemoglobin, the α-cpβ heterodimer exhibits a stronger ligand binding affinity. Knowledge of the intermolecular interactions favoring formation of the α-cpβ heterodimer will be instrumental in understanding the …
Structural Studies Of Blood Coagulation Factor Viii In Complexes With Inhibitory Antibodies, Rachel Werther
Structural Studies Of Blood Coagulation Factor Viii In Complexes With Inhibitory Antibodies, Rachel Werther
WWU Graduate School Collection
Normal blood clotting is regulated by blood plasma protein factors in a blood coagulation cascade. Deficiency in one of these proteins, Factor VIII (FVIII), causes the disease hemophilia A, in which the patient is unable to form blood clots. Treatment of hemophilia A involves the infusion of FVIII, and the most common complication in this treatment is the development of antibodies against the therapeutic infusions. Two mouse monoclonal anti-human antibodies, 3E6 and G99, were used as models of inhibitory action against FVIII by binding to the C-terminal C2 domain. A classical antibody, 3E6, blocks the ability of FVIII to bind …
The Isolated Sixth Gelsolin Repeat Of Villin Has A Calcium-Regulated Structure And Lacks Capacity To Bind F-Actin, Jacob A. Brockerman
The Isolated Sixth Gelsolin Repeat Of Villin Has A Calcium-Regulated Structure And Lacks Capacity To Bind F-Actin, Jacob A. Brockerman
WWU Graduate School Collection
Villin is a modular, epithelial, actin binding protein responsible for the regulation of microvilli in the brush border region of the small intestine and kidney. Villin is regulated by tyrosine phosphorylation, Phosphatidylinositol 4,5-bisphosphate and calcium concentration. These signal molecules control villin's multifunctionality and allow it to switch among its several opposing functional roles. Villin can cleave, nucleate, cap and bundle F-actin. This is achieved through villin's six gelsolin-like domains which are connected by a 40 residue linker sequence to a novel C-terminal headpiece domain (HP). It is known that the HP forms a calcium insensitive F-actin binding site that is …
Performance Of Oriented Fluorophore Luminescent Solar Concentrators, Tristan Butler
Performance Of Oriented Fluorophore Luminescent Solar Concentrators, Tristan Butler
WWU Graduate School Collection
Solar power is likely to play a significant role in the future of fossil fuel alternatives. In order to maximize its impact, the cost of solar power must be competitive with fossil fuels on the global energy market. Luminescent Solar Concentrators are an attractive technology that can potentially reduce the cost of solar power. LSCs utilize cheap materials and no moving parts to concentrate light, however the amount of solar concentration is limited by loss mechanisms inherent in LSCs. One potential method to improve the efficiency of LSCs is through the use of oriented fluorophores. Based on theory presented in …
Gold(I)-Catalyzed Rearrangements Of Allyl Aryl Ethers: Mechanisitc And Synthetic Studies, Heidi E. Dimmitt
Gold(I)-Catalyzed Rearrangements Of Allyl Aryl Ethers: Mechanisitc And Synthetic Studies, Heidi E. Dimmitt
WWU Graduate School Collection
Gold catalyzed reactions are an active area of interest for synthetic chemists due to gold's ability to promote formation of carbon-carbon bonds. A mechanistic study of the aromatic Claisen rearrangement of allyl aryl ethers in the presence of a gold catalyst has shed some light on the role of the gold catalyst in this reaction. Studies probing the electronics requirements of the reaction as well as investigation of stereochemical conservation both support a dissociative ionic mechanism. Our data supports that the catalyst interacts primarily with the alkene branch as opposed to the phenoxide oxygen because the E and Z allyl …
Controlled Growth Of Organic Semiconductor Films In Liquid, Daniel W. (Daniel Wainwright) Shaw
Controlled Growth Of Organic Semiconductor Films In Liquid, Daniel W. (Daniel Wainwright) Shaw
WWU Graduate School Collection
Organic molecular crystalline (OMC) films are being investigated for use in a wide range of potential applications, from field effect transistors, to light-emitting diodes, and photovoltaic cells. The ultimate utility of OMC materials for such applications will depend on the degree and type of molecular order in deposited films, as well as the processing costs for preparing them. The goal of this thesis is to develop a method to produce high quality OMC thin films under ambient conditions, to characterize those films, and their growth kinetics. In particular, I will investigate OMC film growth by ambient axisymmetric spray method, a …
Preparation Of Z-Substituted Styrenes Using Hiyama And Suzuki Cross Couplings: A Synthesis Of Glandulone B, Courtney A. Engles
Preparation Of Z-Substituted Styrenes Using Hiyama And Suzuki Cross Couplings: A Synthesis Of Glandulone B, Courtney A. Engles
WWU Graduate School Collection
The heliannuols are a family of allelochemicals that have been isolated from the common sunflower (Helianthus annuus). The 8-membered cyclic ether moiety found in many of the heliannuols is a rare motif in nature and provides a challenging synthetic target. It has been found that conformational constraint in the form of a Z olefin helps promote the cyclization of aryl epoxides to the 8-membered cyclic ether. Hiyama couplings of aryl iodides and cyclic vinyl siloxanes produce Z-styrenes in good to excellent yields. Due to the expense of the catalyst used for the synthesis of the siloxanes, an alternate pathway to …
Oriented Fluorophore Luminescent Solar Concentrators, Christopher J. (Christopher John) Westcott
Oriented Fluorophore Luminescent Solar Concentrators, Christopher J. (Christopher John) Westcott
WWU Graduate School Collection
Though the sun's energy is the world's most prominent renewable energy resource, technologies such as photovoltaics (PVs) have yet to become a significant factor in the energy market due in part to the sheer cost of unit deployment. Luminescent Solar Concentrators (LSCs) have been investigated since the late 1960s as a means of reducing the cost of PV arrays by replacing large areas of expensive PVs with cheaper materials such as glass or plastic. LSCs function by using fluorescent dyes embedded in a host matrix that absorb the sun's rays and redirects the light through total internal reflection to small …
Hydrodesulfurization And Hydrodeoxygenation Over Noble Metal Phosphide Catalysts, Richard H. Bowker
Hydrodesulfurization And Hydrodeoxygenation Over Noble Metal Phosphide Catalysts, Richard H. Bowker
WWU Graduate School Collection
As the demand and price for crude petroleum continues to increase, unconventional sources of petroleum, including tar sands, oil shales, and bio-derived oils have become economically viable feedstocks. Previously, these oil reserves were deemed too costly to process into fuels due to the high impurity content (S, N, O) of the unrefined feedstocks. The decline in conventional oil reserves has focused increasing attention on utilizing these unconventional feedstocks. However, stringent environmental regulations governing fuel impurity content require refineries to remove these impurities in increasing amounts. Current hydrotreatment catalysts are unable to effectively remove theses impurities in sufficient quantities to meet …
Ambient Pressure Organic Semiconductor Thin Film Growth By Ambient Axisymmetric Spray, Kevin A. (Kevin Anthony) Bufkin
Ambient Pressure Organic Semiconductor Thin Film Growth By Ambient Axisymmetric Spray, Kevin A. (Kevin Anthony) Bufkin
WWU Graduate School Collection
Interest in using organic semiconductors in applications such as large area displays, photovoltaic devices, and radio frequency identification tags stems in part from their prospects for enabling significantly reduced manufacturing costs compared to traditional inorganic semiconductors. However many of the best performing prototype devices produced so far have involved expensive or time-consuming fabrication methods, such as the use of single crystals or thin films deposited under high vacuum conditions. This thesis examines a new approach for growing low molecular weight organic crystalline films at ambient conditions based on an organic vapor-liquid-solid growth (OVLS) mechanism using thermotropic nematic liquid crystal (LC) …
Structural Characterization Of Cytoskeleton Regulating Protein Villin And Its C-Terminal Modular Domains, Danielle A. Pfaff
Structural Characterization Of Cytoskeleton Regulating Protein Villin And Its C-Terminal Modular Domains, Danielle A. Pfaff
WWU Graduate School Collection
Villin is a modular protein that regulates F-actin bundles in the microvilli of absorptive epithelial cells in the intestine. At low (10-100 nM) calcium levels, Villin is an F-actin bundling agent supporting the specialized brush border membrane of the absorptive epithelium. At intermediate micromolar calcium levels, Villin nucleates and caps the barbed ends of F-actin and in high (> 100 μM) calcium Villin is an F-actin severing agent (Bretsher & Weber, 1980; Glenney et al., 1980, 1981; Mooseker et al. 1980). The amino acid sequence of Villin has seven modular domains. The first six Villin domains (D1-D6) form a "core" …
Activation And Inhibition Of Gtpase Translation Factors On The Prokaryotic Ribosome, Justin D. Walter
Activation And Inhibition Of Gtpase Translation Factors On The Prokaryotic Ribosome, Justin D. Walter
WWU Graduate School Collection
Throughout all domains of life, each protein in a cell is synthesized by a remarkable biomolecular machine called the ribosome, in a process referred to as translation. This process is regulated by proteins called translation factors, several of which belong to the GTPase superfamily of enzymes which require the binding and subsequent hydrolysis of guanosine 5'-triphosphate (GTP) to execute their function. In contrast to the regulatory role of translation factors, protein biosynthesis is inhibited by several naturally occurring antibiotics. While our understanding of translation has been revolutionized by the recent elucidation of atomic-resolution x-ray crystal structures of the ribosome trapped …
Copper-Catalyzed Diboration Of Ketones: Facile Synthesis Of Tertiary A-Hydroxyboronate Esters, Melissa Mcintosh
Copper-Catalyzed Diboration Of Ketones: Facile Synthesis Of Tertiary A-Hydroxyboronate Esters, Melissa Mcintosh
WWU Graduate School Collection
The versatility of the C-B bond in organic synthesis has led to extensive development of new methods for the selective incorporation of boron into organic substrates. The incorporation of boron substituents alpha to heteroatoms provides direct entry into substrates analogous to those formed and utilized in the Matteson homologation reaction. Our group has explored the diboration of various ketones using the (ICy)CuOt-Bu catalyst developed by Sadighi and co-workers. We found that (ICy)CuOt-Bu could be generated in situ using 3 mol % (ICy)CuCl and 5 mol% NaOt-Bu (Scheme 1). This catalyst system was shown to cleanly afford the diboration of various …