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Articles 1 - 26 of 26
Full-Text Articles in Chemistry
Characterization Of Sufs And Sufe Of Suf Pathway For Fe-S Cluster Assembly In Escherichia Coli, Guangchao Dong
Characterization Of Sufs And Sufe Of Suf Pathway For Fe-S Cluster Assembly In Escherichia Coli, Guangchao Dong
Theses and Dissertations
Fe-S clusters are one major type of the sulfur-containing cofactors, which conduct essential functions in organisms. The Suf pathway is one of the three main pathways for the biosynthesis of Fe-S clusters. In E. coli, the Suf pathway is utilized under iron limitation and oxidative stress. This ability is important for pathogens to survive. Also, the Suf pathway is found to be exclusive in bacteria, so it is a good target for novel antibiotic design. SufS is a cysteine desulfurase in the Suf pathway to extract sulfur from L-cysteine. It needs the enhancement of SufE. To better understand the catalytic …
Advances In Chemistry, Part I: Noise, Calibration, And Educational Advances In Analytical Chemistry. Part Ii: Safety Oversight In Chemical Journals, Lauren E. Grabowski
Advances In Chemistry, Part I: Noise, Calibration, And Educational Advances In Analytical Chemistry. Part Ii: Safety Oversight In Chemical Journals, Lauren E. Grabowski
Theses and Dissertations
Part I:
The accuracy and precision of the results of any chemical analysis depends on the calibration graph and its associated systematic and random errors. Least squares regression generally treats all data with equal weights. A weighted least-squares fit is an improvement but requires knowledge of the imprecision in each point of the calibration graph. The imprecision is not easy to estimate with high confidence because of the large number of replicates needed.
The imprecision depends on the types and magnitudes of the sources of noise. We characterized the noise sources in ICP-OES and UV/Vis and developed a model that …
Antimicrobial Biomaterials And Sustainable Polymers From Renewable Biomass, Mitra Shiran Ganewatta
Antimicrobial Biomaterials And Sustainable Polymers From Renewable Biomass, Mitra Shiran Ganewatta
Theses and Dissertations
In this dissertation, development of antimicrobial biomaterials and sustainable polymers from renewable biomass is described. In Chapter 1, an overview and recent development about sustainable polymers from renewable biomass, antimicrobial biomaterials and polymerization methods are given. Afterwards, the major research objectives of this doctoral research work are described.
Innovative cationic polymers containing pine resin sourced abietic acid is discussed in Chapter 2. The preparation of cationic compounds is conversed via a combination of Diels-Alder, catalytic esterification, quaternization and subsequent decoration of polycaprolactone that was prepared via ring-opening polymerization (ROP). Furthermore, the antimicrobial activity against a range of bacteria, biocompatibility with …
Shaping Metallic Nanoparticles Toward Integrated Plasmonics And Catalysis, Qingfeng Zhang
Shaping Metallic Nanoparticles Toward Integrated Plasmonics And Catalysis, Qingfeng Zhang
Theses and Dissertations
Noble metal nanoparticles have been of tremendous interest because of their intriguing size- and shape-dependent plasmonic and catalytic properties. The combination of tunable plasmon resonances with superior catalytic activities on the same nanoparticle, however, has long been challenging because plasmonics and catalysis require nanoparticles in two drastically different size regimes. Tunable plasmon resonances is a unique feature of sub-wavelength metallic nanoparticles, whereas heterogeneous catalysis requires the use of sub-5 nm nanoparticles as the catalysts. In this dissertation, I firstly found a unique way to bridge this size gap between nanoplasmonics and nanocatalysis. I demonstrated that desired plasmonic and catalytic properties …
Chemical Sensing In Harsh Environments By Multivariate Optical Computing, Christopher Michael Jones
Chemical Sensing In Harsh Environments By Multivariate Optical Computing, Christopher Michael Jones
Theses and Dissertations
Multivariate optical computing (MOC) is a compressive sensing technique for which an analyte concentration is detected in an interfering mixture by direct detector output. The detector measures the dot product of a linear regression vector with a sample spectrum, as an analog optical computation. The computation is accomplished with the multivariate optical element (MOE), to which the optical regression vector is encoded as a transmission pattern. As a spectrum of light emanates from a sample and passes through the MOE, the dot product naturally occurs when light strikes the detector. The MOC platform allows a simple, robust, and direct measurement …
Mechanistic Studies Of Nucleic Acid Chaperone Activities Of Retroviral Nucleocapsid Protein, Lichao Sun
Mechanistic Studies Of Nucleic Acid Chaperone Activities Of Retroviral Nucleocapsid Protein, Lichao Sun
Theses and Dissertations
In this dissertation, I have used single molecule Fluorescence Resonance Energy Transfer (sm-FRET), as a nanoscale spectroscopic ruler to gain quantitative, molecular-level understanding about the kinetics and mechanism of NC-chaperoned TAR sequence rearrangements. Firstly, I have resolved the complex kinetics and underlying reaction pathways of TAR sequence annealing in the presence of HIV-1 NC over a broad NC concentration by performing the time-resolved sm-FRET measurements in a unique aggregation-free environment. I have further gained the insights that the NC-induced secondary structural changed of TAR hairpins modulate the annealing pathways and consequently affect the overall kinetics of the TAR sequence annealing. …
Development Of An Electrochemical Method To Study Real-Time In Vivo Neurotransmitter Modulation, Srimal Aminda Samaranayake
Development Of An Electrochemical Method To Study Real-Time In Vivo Neurotransmitter Modulation, Srimal Aminda Samaranayake
Theses and Dissertations
Histamine and serotonin are important biogenic amines that regulate vital brain functions. These two transmitters are thoughts to be involved in neurodegenerative diseases such as Parkinson’s and Alzheimer’s and affective disorders including depression. Histamine and serotonin are believed to regulate each other but their fundamental neuromodulation mechanisms are not well understood. This lack of understanding makes brain disorders implicating these two transmitters difficult to diagnose and treat. Our lab extensively investigates the serotonergic system to understand serotonin’s neurochemistry in the brain. However, histamine is relatively understudied with respect to other biogenic amines because of an absence of suitable analytical tools. …
Synthesis, Characterization And Application Of Polymer-Grafted Nanoparticles, Yang Zheng
Synthesis, Characterization And Application Of Polymer-Grafted Nanoparticles, Yang Zheng
Theses and Dissertations
This work focused on the synthesis and characterization of polymer-grafted nanoparticles for various applications including drug-delivery, directed self-assembly and mechanical reinforcement applications. The surfaces of inorganic particles were modified with polymers of different composition, chain length, graft density and polymer architecture depending on the specific needs of each project. The surface modifications were mainly achieved by surface-initiated reversible addition fragmentation chain transfer (RAFT) polymerization, which is a very versatile technique to prepare nanocomposites with desired properties.
The first part of this work (Chapters 2 & 3) focused on novel self-assembly techniques. Chapter 2 described the design and characterization of a …
Silylation-Based Kinetic Resolution Of 2-Arylcyclohexanols And Understanding Internal Chirality Transmission Via Circular Dichroism, Li Wang
Theses and Dissertations
This work described herein focuses on the silylation-based kinetic resolution methodology developed by the Wiskur group in 2011. It is a powerful method for the separation of a single enantiomer from a mixture of racemic secondary alcohols. Chapter one is a summary of the background and related works of this methodology.
In chapter two, the silylation-based kinetic resolution of various trans 2-arylcyclohexanols will be discussed by employing a p-isopropyl triphenylsilyl chloride as the derivatizing reagent with (-)-benzotetramisole as the catalyst. The diastereoselective and enantioselective of trans alcohols over the cis will be investigated and a facial one-pot reaction sequence will …
Polymer Grafted Nanoparticles For Designed Interfaces In Polymer Nanocomposites, Mohammad Mohammadkhani
Polymer Grafted Nanoparticles For Designed Interfaces In Polymer Nanocomposites, Mohammad Mohammadkhani
Theses and Dissertations
This dissertation presents the design, synthesis, and characterization of polymer nanocomposite interfaces and the property enhancement from this interface design. Through the use of reversible addition fragmentation chain transfer (RAFT) polymerization for the grafting of polymer chains to silica nanoparticles, the surface of silica nanoparticles can be manipulated to tune the properties of nanocomposites by controlling the interface between the particles and the polymer matrix.
In the first part of this work, compatibility of 15 nm silica nanoparticles grafted with different alkyl methacrylates with linear low density polyethylene was investigated. SI-RAFT polymerization of hexyl, lauryl, and stearyl methacrylate on silica …
Assessing Aberrant Glycosylation With Synthetic Lectins To Detect And Stage Prostate Cancer, Anna Veldkamp
Assessing Aberrant Glycosylation With Synthetic Lectins To Detect And Stage Prostate Cancer, Anna Veldkamp
Theses and Dissertations
Aberrant glycosylation takes place during the onset of cancer and throughout the progression of the disease allowing certain glycans to serve as biomarkers1. Boronic acid functionalized synthetic lectins (SLs) have been shown to bind selectively and crossreactively to certain glycoproteins through covalent yet reversible interactions between the boronic acids and 1,2- or 1,3-diols found on saccharides2. This project focuses on 1) data acquisition optimization of an existing SL array; 2) the identification, isolation, and characterization of new SLs that interact with proteins and glycoproteins targeting the prostate and prostate cancer; and 3) the utilization of new SLs in cross-reactive sensor …
Fast Scan Cyclic Voltammetry For Real-Time Metal Speciation Analysis, Hettige. M. Thushani Siriwardhane
Fast Scan Cyclic Voltammetry For Real-Time Metal Speciation Analysis, Hettige. M. Thushani Siriwardhane
Theses and Dissertations
Electrochemistry is a powerful analytical tool that has been widely used to detect trace metals in natural systems. However, studying the speciation of metals during dynamic events, such as storms and floods, is analytically challenging due to the limited temporal resolution of traditional electrochemical techniques. Additionally, most techniques report the total metal concentration (both complexed and free) that does not reflect the toxicity of these metals, which arise mostly from the free state. To overcome these issues, we previously pioneered the use of fast scan cyclic voltammetry (FSCV) to measure free copper (Cu(II)) and lead (Pb(II)) in real-time in laboratory …
Characterization Of The Suf Fe-S Pathway In Escherichia Coli, Naimah Bolaji
Characterization Of The Suf Fe-S Pathway In Escherichia Coli, Naimah Bolaji
Theses and Dissertations
Iron is an essential transition metal required by almost all organisms for use as a cofactor in many metabolic processes such as respiration and photosynthesis. Iron can be combined with elemental sulfur to form an iron-sulfur (Fe-S) cluster. In bacterial pathogens, Fe-S cluster cofactors carry out critical functions and the Fe-S cluster biogenesis pathway is essential for their survival. In E. coli, the Suf pathway assembles Fe-S clusters under conditions of iron starvation and oxidative stress. While some mechanistic details of the Fe-S cluster biogenesis have been well-characterized, the process of in vivo iron donation remains unclear. Iron storage proteins …
The Development Of Novel Hybridized Hyaluronic Acid Biomaterials For Applications In Tissue Engineering And Controlled Drug Delivery, Panita Maturavongsadit
The Development Of Novel Hybridized Hyaluronic Acid Biomaterials For Applications In Tissue Engineering And Controlled Drug Delivery, Panita Maturavongsadit
Theses and Dissertations
This thesis is focused on the development of novel hybridized biomaterials for applications in tissue engineering and controlled drug delivery. Two types of materials used in my research are biopolymers and nanomaterials. Hyaluronic acid (HA), a natural polymer commonly found in extracellular matrix (ECM), was the primary polymer used in my research due to biocompatibility, biodegradability and the ease of manipulation to offer a wide range of physical and mechanical properties. Meanwhile, the nanomaterials, including Tobacco mosaic virus (TMV), gold nanorods and graphene, provide attractive properties, such as a nanoscale topography, biochemistry, high surface area, and special chemical and electrical …
Materials Discovery Of Reduced Early Transition Metal Compounds: Crystal Growth And Characterization, Dileka Abeysinghe
Materials Discovery Of Reduced Early Transition Metal Compounds: Crystal Growth And Characterization, Dileka Abeysinghe
Theses and Dissertations
Materials discovery via crystal growth is an active area of research that has led to the preparation of many novel materials along with the determination of their crystal structures. One sub-category in this diverse field of materials is the preparation of early transition metal reduced oxides. These reduced oxides often exhibit unusual electronic and magnetic properties. Due to the synthetic challenges associated with early transition metal reduction, new and facile methods to prepare reduced oxides is of great interest. These limitations can be overcome by using a carefully selected redox neutral flux, a vacuum sealed fused silica tube, and metal …
Disinfection By-Products: Formation In Pool Water And The Role Of Iodinated Medical Imaging Compounds As A Potential Precursor In The Formation Of Iodo-Dbps, Christina Marie Joseph
Disinfection By-Products: Formation In Pool Water And The Role Of Iodinated Medical Imaging Compounds As A Potential Precursor In The Formation Of Iodo-Dbps, Christina Marie Joseph
Theses and Dissertations
Disinfection by-products (DBPs) are the unintended consequence of using chemical disinfectants to kill pathogens in water. 1-11 They are formed from the reaction between disinfectants and natural organic matter (NOM), anthropogenic contaminants, and bromide/iodide present in the raw source water. DBPs are cause for concern because studies have found them to be toxic.11-16 This research focuses on identifying and studying the formation of DBPs. Specifically, the presence of DBPs in chlorinated pool water and tap water from Barcelona, Spain was studied to better understand which DBPs are formed in the pool as compared to those that enter the pool from …
Investigation Of Iron(Ii) Autoxidation Rate And Iron Mediated Geochemical Production Of Reactive Oxygen Species At Oxic-Anoxic Interfaces, Dewamunnage Muditha Chathurangani Dias
Investigation Of Iron(Ii) Autoxidation Rate And Iron Mediated Geochemical Production Of Reactive Oxygen Species At Oxic-Anoxic Interfaces, Dewamunnage Muditha Chathurangani Dias
Theses and Dissertations
Biogeochemical cycles in ecosystems regulate the flow of energy between reduced species (typically carbon compounds) and a variety of oxidants via both biotic and abiotic reactions. A key class of chemical compounds that can link these cycles through abiotic pathways are Reactive Oxygen Species (ROS). The production of ROS via photochemical pathways is well known. More recently, the non-photochemical production of ROS via the one electron oxidation of ferrous iron (Fe(II)) by dioxygen (O2) has been detected in a range of environments. The oxidation of Fe(II) initiates a pathway that generates an array of ROS as Fe is cycled between …
Fluorescence Polarization Measurements To Probe Alignment Of A Bithiophene Dye In One-Dimensional Channels Of Self-Assembled Phenylethynylene Bis-Urea Macrocycle Crystals, Preecha Kittikhunnatham
Fluorescence Polarization Measurements To Probe Alignment Of A Bithiophene Dye In One-Dimensional Channels Of Self-Assembled Phenylethynylene Bis-Urea Macrocycle Crystals, Preecha Kittikhunnatham
Theses and Dissertations
This thesis describes the use of polarized fluorescence microscopy to directly probe guest molecule orientation in bis-urea macrocycle crystals. These macrocycles assemble to afford one-dimensional (1D) microchannels ∼9 Å in diameter that have previously been shown to exhibit normal Fickian diffusion and induce selective reactivity among the confined guest molecules. In the present work, we take advantage of the quasi-1D morphology of fiber-like microcrystals with the extended dimension corresponding to the channel axis to measure excitation and emission polarization values for a bithiophene guest. Guest fluorescence is shown to be polarized along the fiber axis with emission polarization values up …
Targeting Aberrant Glycosylation In Colon And Prostate Cancer With An Improved Synthetic Lectin Array, Tanya Hundal
Targeting Aberrant Glycosylation In Colon And Prostate Cancer With An Improved Synthetic Lectin Array, Tanya Hundal
Theses and Dissertations
Cancers of the colon and prostate, though treatable, necessitate early detection to improve patient outcomes. Current diagnostics, (visual methods or biopsies) besides being invasive, are subjective towards interpretation, thus decreasing accuracy. Alternatively, blood-based tests involving measuring of specific biomarkers (like CEA and PSA for colon and prostate cancers, respectively) are associated with high false-positive rates and are more useful for monitoring post-treatment patient health, thus driving efforts to identify better screening and diagnostic techniques.
Abnormal glycosylation of integral membrane and secreted glycoproteins is known to take place at the onset of many diseases, including cancer, and presents as the over, …
Kinetic-Control Of Block Copolymer Micelles For Tunable Nanomaterials Towards Energy Devices, Hasala Nadeesini Lokupitiya
Kinetic-Control Of Block Copolymer Micelles For Tunable Nanomaterials Towards Energy Devices, Hasala Nadeesini Lokupitiya
Theses and Dissertations
Nano-scale inorganic porous materials are crucial for numerous applications ranging from electronics to energy conversion. The ability to control the morphology and the key architectural parameters of nanomaterials largely determines the transport characteristics and performance of such devices. But, there is very little understanding and development to tune these key architectural parameters such as inorganic wall-thickness and pore diameter. Even though there are numerous examples available on the fabrication of porous nanomaterials via block copolymer co-assembly, there is limited understanding on independent control over key architectural parameters. Because of that the major focus of this thesis is to explore and …
Coordination Chemistry Of Carboranes And Furan Ligands On Transition Metal Cluster Complexes, Emmanuel Joseph Kiprotich
Coordination Chemistry Of Carboranes And Furan Ligands On Transition Metal Cluster Complexes, Emmanuel Joseph Kiprotich
Theses and Dissertations
Chapter 1 presents the most relevant literature in the field of carborane chemistry. The focus is on icosahedral carboranes and the different methods of boron or carbon atoms substitution and functionalization. The direct addition of transition metal to boron atoms is covered in detail as well as strategies for cage opening of icosahedral carboranes.
Chapter 2 reports the preparation of some of the first polynuclear metal carbonyl cluster complexes where the closo-carborane cage: o-C2B10H12 serves as a ligand on the face of one (Os3(CO)9(µ3-4,5,9-C2B10H10 …
Elucidation Of Protein Interactions And The Re-Tuning Of Porphyrin Electronics For Hydroxylases, Steven Charles Ratigan
Elucidation Of Protein Interactions And The Re-Tuning Of Porphyrin Electronics For Hydroxylases, Steven Charles Ratigan
Theses and Dissertations
Non-Ribosomal Peptide Synthetases (NRPSs) and their exogenous tailoring partners have been heavily studied but not in the context of non-cognate systems. Orf78, a dinuclear iron β-hydroxylase from the lysobacter pathway and homologous to CmlA from the chloramphenicol pathway, is used to test affinities for one native and two non-native T-domains. Results indicate that there is enough difference between Type I and Type II NRPS systems to disfavor common recognition motifs. Additionally, the β-hydroxylase P450sky, from the skyllamycin biosynthetic pathway, is used in conjunction with the NRPS ATdomain NikP1AT from the nikkomycin biosynthetic pathway, in lieu of the homolog P450nikQ. The …
Structural And Functional Studies Of Proteins From The Agricultural Pests Tetranychus Urticae And Aspergillus Fumigatus, Caleb Schlachter
Structural And Functional Studies Of Proteins From The Agricultural Pests Tetranychus Urticae And Aspergillus Fumigatus, Caleb Schlachter
Theses and Dissertations
Agricultural pests are a worldwide problem and cause billions of dollars in crop loss. In the United States alone, an estimated $40 billion USD is lost per year due to insecticide resistance [1]. Studied here are proteins (potentially new pesticide targets) from the agricultural pests Tetranychus urticae and Aspergillus fumigatus. T. urticae, or twospotted spidermite, is a polyphagous pest, and three proteins from this pest, a cyanase, a glutathione S-transferase and an intradiol ring-cleavage dioxygenase are described [2]. Cyanase is involved in the conversion of bicarbonate and cyanate, a toxic self-defense metabolite produced by plants, into ammonia and carbon dioxide. …
Sustainable Polymeric Materials Derived From Plant Oils: From Synthesis To Applications, Xinzhou Zhang
Sustainable Polymeric Materials Derived From Plant Oils: From Synthesis To Applications, Xinzhou Zhang
Theses and Dissertations
In this thesis, monomers and polymers derived from high oleic soybean oil are investigated. The properties of these monomers and polymeric materials are characterized and discussed. Chapter 1 describes an overall background of bio-based resources, monomers, polymers, and their potential impact on society. The overall objective of my research is described. Chapter 2 outlines a new large-scale preparation of a soybean based monomer and the use of this monomer in thermoplastic elastomers. The synthetic procedures and characterizations of the monomers and polymers are discussed. In Chapter 3, potential applications of soybean oil monomers in both supramolecular polymers and poly(phosphoester)s are …
Redirecting P450 Ferryl-Oxo Intermediates From Oxygenation To Decarboxylation, Job Logan Grant
Redirecting P450 Ferryl-Oxo Intermediates From Oxygenation To Decarboxylation, Job Logan Grant
Theses and Dissertations
A recently discovered cytochrome P450 has garnered much interest for its ability to oxidatively decarboxylate n length fatty acids to n-1 terminal olefins using hydrogen peroxide as an oxidant. This enzyme (P450 OleT) is mechanistically peculiar, as it seemingly abrogates the oxygen insertion chemistry that typifies the P450 superfamily. In this work we explore the origin of this deviant catalysis.
Using stopped-flow and transient kinetic methodologies the ferryl-oxo pi-cation radical and ferryl-hydroxo intermediates, known as compound-I (Cpd-I) and compound-II (Cpd-II) respectively, were isolated in high yield. This is the first time either species has been observed in a substrate bound …
Metal-Organic Frameworks: A Versatile Platform For Light Harvesting And Energy Transfer, Derek E. Williams
Metal-Organic Frameworks: A Versatile Platform For Light Harvesting And Energy Transfer, Derek E. Williams
Theses and Dissertations
The global energy demand is undoubtedly rising at an alarming rate, and as a result, humanity faces the problem of finding alternative energy supplies. Approximately 80 percent of the world’s energy currently comes from fossil fuels, and only a small fraction, 10 percent, from renewable energy sources. The study of energy transfer (ET) processes is a rapidly developing area of interest due to the necessity for more efficient photovoltaic devices, which are crucial to meet the growing energy demand. A promising approach to further advance organic photovoltaics is to precisely arrange many lightharvesting chromophores (e.g., porphyrin derivatives), attainable through a …