Chemistry Commons^™

Solvent Stable Microbial Lipases: Current Understanding And Biotechnological Applications, Barry Ryan, Priyanka Priyanka, Yeqi Tan, Gemma K Kinsella, Gary T. Henehan

Articles

Objective: This review examines on our current understanding of microbial lipase solvent tolerance, with a specific focus on the molecular strategies employed to improve lipase stability in a non-aqueous environment.

Results: It provides an overview of known solvent tolerant lipases and of approaches to improving solvent stability such as; enhancing stabilising interactions, modification of residue flexibility and surface charge alteration. It shows that judicious selection of lipase source supplemented by appropriate enzyme stabilisation, can lead to a wide application spectrum for lipases.

Conclusion: Organic solvent stable lipases are, and will continue to be, versatile and adaptable biocatalytic workhorses commonly employed …

Chemical Analysis Of Aerosol Particle Surfaces, Hillary Woolf

Fall Student Research Symposium 2018

Aerosol particles are thought to impact climate properties. The ability to probe aerosols to understand their chemical properties has been difficult due to a lack of appropriate analytical techniques. Here we present interface-specific SHS techniques to allow for in situ analysis of aerosol particles. Transportation of aerosols from their collection site to the laboratory disturbs their chemical and physical properties thus making it difficult to take accurate measurements of aerosol particles. We show that using a CCD detector is a more effective option for producing more sensitive results and can greatly reduce sampling time and could possibly detect measurements from …

Chemistry Student Attitudes And Utilization Of Office Hours, Dieng Barbacar, Edgar Gomez, Andre Rodriguez

Publications and Research

While research has demonstrated that faculty-student interactions increase retention and graduation rates, faculty often report that their office hours are underutilized. To better understand students’ attitudes, usage and plans towards faculty hours a survey was administered in the second to third week of the fall 2018 semester to students in 5 sections of general chemistry courses. The goal was to better understand how students perceive the benefits and hindrances of office hours, along with current or planned attendance. Prior to survey administration, it was speculated that not attending office hours could be because they were not scheduled at a convenient …

Synthesis And Integration Of Oligoviologens Into Hydrogel Actuators, Kevin Liles

Arts & Sciences Graduate Student Theses and Dissertations

Interest in the development of soft-material artificial molecular muscles has inspired scientists to pursue novel stimuli-responsive systems capable of undergoing change in the physical and mechanical properties of a material in response to external stimuli. This interest has been driven primarily by advances, or the desire for advances, in fields such as soft robotics, microfluidics, and bio-compatible drug-delivery systems. In this work, redox-responsive viologens and their ability to form stable radical-cation complexes were evaluated as a method of actuation in stimuli-responsive materials, specifically hydrogels. First, a brief overview of hydrogel actuators is covered, with some examples given of the broad …

Canvass: A Crowd-Sourced, Natural-Product Screening Library For Exploring Biological Space, Sara E. Kearney, Gergely ZahoráNszky-KőHalmi, Kyle R. Brimacombe, Mark J. Henderson, Caitlin Lynch, Tongan Zhao, Kanny K. Wan, Zina Itkin, Christopher Dillon, Min Shen, Dorian M. Cheff, Tobie D. Lee, Danielle Bougie, Ken Cheng, Nathan P. Coussens, Dorjbal Dorjsuren, Richard T. Eastman, Ruili Huang, Michael J. Iannotti, Surendra Karavadhi, Carleen Klumpp-Thomas, Jacob S. Roth, Srilatha Sakamuru, Wei Sun, Steven A. Titus, Adam Yasgar, Ya-Qin Zhang, Jinghua Zhao, Rodrigo B. Andrade, M. Kevin Brown, Robert B. Grossman

Chemistry Faculty Publications

Natural products and their derivatives continue to be wellsprings of nascent therapeutic potential. However, many laboratories have limited resources for biological evaluation, leaving their previously isolated or synthesized compounds largely or completely untested. To address this issue, the Canvass library of natural products was assembled, in collaboration with academic and industry researchers, for quantitative high-throughput screening (qHTS) across a diverse set of cell-based and biochemical assays. Characterization of the library in terms of physicochemical properties, structural diversity, and similarity to compounds in publicly available libraries indicates that the Canvass library contains many structural elements in common with approved drugs. The …

Computational Studies Of Fullerene-Porphyrin Dyads, Sumreen Gul

Theses and Dissertations

Fullerene (C60) has generated much scientific interest since its discovery due to its novel optical, electronic, and physical properties. Fullerene has been shown to be an excellent electron acceptor and as a result is the acceptor of choice in organic photovoltaics. Porphyrins are excellent electron-donors due to their stability, low ionization potential, and excellent light absorption properties. As a result, fullerene-porphyrin dyads form unique donor-acceptor systems that can be useful for a variety of photoactive applications. In this research, computational studies have been performed on different varieties of C60-Porphyrin dyads and the relationship between molecular topology and the properties of …

Synthesis, Characterization And Enhanced Electrochemical Performance Of Amide-Based Metal Complexes As Electrocatalysts In Energy Devices And Non-Enzymatic Sensor, Charlette Parnell

Theses and Dissertations

The use of metal catalysts supported on the carbon nanomaterials as electrocatalysts has propelled the development of modified electrodes for electrochemical studies. They have been shown to increase sensitivity and electrical conductivity making them advantageous in applications for fuel cells, sensors and supercapacitors. In this dissertation, the synthesis and characterization of metal catalysts supported on carbon nanomaterials will be discussed and their electrochemical activity towards fuel cells, sensor and supercapacitor studies will be explored. Due to the great need for energy efficient and environmentally benign energy devices that can replace the use of fossil fuels in energy production, fuel cells …

Synthesis Of 5,6-Diaminoacenaphthylene By Reduction Of Sterically Crowded Nitro Groups With Sodium Dithionite, Amber J. Dood, Patrick A. Fisher, Christine L. Bodden, Luke J. Peterson, Kathryn A. Lindberg, Trevor A. Coeling, Douglas C. Yarbrough, Jason G. Gillmore

Faculty Publications

5,6-Diaminoacenaphthylene was synthesized in four steps from acenaphthene. This seemingly simple molecule provides unique synthetic challenges because it is relatively difficult to reduce the nitro groups and the molecule contains a particularly reactive double bond. It was determined that the only feasible sequence for the synthesis was to nitrate acenaphthene, then brominate, eliminate, and finally selectively reduce. Several reduction methods were attempted before finding one that would completely reduce both nitro groups while leaving the double bond intact.

A Simple And Robust Approach To Reducing Contact Resistance In Organic Transistors, Zachary A. Lamport, Katrina J. Barth, Hyunsu Lee, Eliot Gann, Sebastian Engmann, Hu Chen, Martin Guthold, Iain Mcculloch, John E. Anthony, Lee J. Richter, Dean M. Delongchamp, Oana D. Jurchescu

Chemistry Faculty Publications

Efficient injection of charge carriers from the contacts into the semiconductor layer is crucial for achieving high-performance organic devices. The potential drop necessary to accomplish this process yields a resistance associated with the contacts, namely the contact resistance. A large contact resistance can limit the operation of devices and even lead to inaccuracies in the extraction of the device parameters. Here, we demonstrate a simple and efficient strategy for reducing the contact resistance in organic thin-film transistors by more than an order of magnitude by creating high work function domains at the surface of the injecting electrodes to promote channels …

H2 Oxidation Over Supported Au Nanoparticle Catalysts: Evidence For Heterolytic H2 Activation At The Metal-Support Interface, Todd N. Whittaker, K. B. Sravan Kumar, Christine Peterson, Meagan N. Pollock, L. C. Grabow, Bert D. Chandler

Chemistry Faculty Research

Water adsorbed at the metal-support interface (MSI) plays an important role in multiple reactions. Due to its importance in CO preferential oxidation (PrOx), we examined H₂ oxidation kinetics in the presence of water over Au/TiO₂ and Au/Al₂O₃ catalysts, reaching the following mechanistic conclusions: (i) O₂ activation follows a similar mechanism to that proposed in CO oxidation catalysis; (ii) weakly adsorbed H₂O is a strong reaction inhibitor; (iii) fast H₂ activation occurs at the MSI, and (iv) H₂ activation kinetics are inconsistent with traditional dissociative H₂ chemisorption on metals. Density …

A New Generation Of Functional Polyisobutylenes For Advanced Applications, Corey M. Parada

Dissertations

Polyisobutylene (PIB) is a fully saturated, aliphatic polymer of high commercial importance due to its superior gas barrier properties and high chemical/oxidative stability. One commercial end-use for PIB is in insulated glass windows (IGU), where it acts as a gas/moisture barrier and sealant. Under certain adverse conditions, catastrophic failure of the PIB sealant may result in aesthetic and functional failure of the IGU, which necessitates replacement of the unit. Thus, there exists a need to improve current generations of thermoplastic PIB sealants to be able to withstand the harsh environments found in current real-world applications.

In the first project, we …

Polyhedral Oligomeric Silsesquioxane-Phosphate Glass Matrix Nanocomposites With Additional Chapter On Phosphate Glass-Poly(Ethylene Terephthalate) Matrix Composites, Kyoungtae Kim

Dissertations

Preparation and characterization of tin fluorophosphate glass (Pglass) matrix nanocomposites incorporating polyhedral oligomeric silsesquioxane (POSS) were investigated on the structural, thermal, morphological, mechanical, and rheological properties. Various processes including synthesis, extrusion and sintering processes were applied to prepare the nanocomposite samples. Another application of POSS with hydrophobic functional groups on the well-structured nanoscale silicate cage with three silanol groups was investigated to present the feasibility to use POSS molecule as a coating material on the surface of the hydrophilic inorganic glass. In addition, Poly(ethylene terephthalate) polymer matrix composites incorporating Pglass was studied to present the benefits of the Pglass with …

Effect Of Network Structure On Free Volume And Gas Transport Properties Of Thiol-Ene And Epoxy-Amine Networks, Ramesh Krishnan Ramakrishnan

Dissertations

Network parameters such as cross-link density or intermolecular interactions were used as effective parameters to control polymer chain packing or free volume and thereby control the mass transport properties of networks.

A series of polyethylene glycol (PEG) based thiol-ene elastomeric networks having a broad range of molecular weight between cross-links, M_c, (inverse of cross-link density) was prepared. The specific volume of the networks was studied as a function of temperature and pressure using high pressure dilatometry, and the obtained PVT data was fit using Simha-Somcynsky equation of state (S-S eos) analysis. Fractional free volume, quantified through S-S eos …

Structure-Property Relationships Of Solvent-Cast Organic Thin Films For Model Corrosion Control Coatings, Austin Maples

Dissertations

This dissertation aimed at answering several fundamental questions, specifically: 1) What is the effect of scribing parameters on visual corrosion assessments? 2) What role do molecular weight, residual solvent, and polymer composition have on morphological changes in organic thin films? 3) What alternatives to visual assessments could be implemented to better understand and detect corrosion before macroscopic failure? This research definitively proved that scribes can vary in type and dimensions, and yet are still comparable if the scribe dimensions before exposure are known. Furthermore, it demonstrated that solvents common to a variety of coating industries could become trapped within the …

Generating High-Order Optical And Spin Harmonics From Ferromagnetic Monolayers, G.P. Zhang, M.S. Si, M. Murakami, Y.H. Bai, Thomas George

Chemistry & Biochemistry Faculty Works

High-order harmonic generation (HHG) in solids has entered a new phase of intensive research, with envisioned band-structure mapping on an ultrashort time scale. This partly benefits from a flurry of new HHG materials discovered, but so far has missed an important group. HHG in magnetic materials should have profound impact on future magnetic storage technology advances. Here we introduce and demonstrate HHG in ferromagnetic monolayers. We find that HHG carries spin information and sensitively depends on the relativistic spin–orbit coupling; and if they are dispersed into the crystal momentum k space, harmonics originating from real transitions can be k-resolved and …

Assessing Biofiltration Without Ozonation For Removal Of Trihalomethane Precursors In Drinking Water At The Beaver Water District Drinking Water Treatment Plant, Sana Ajaz

Graduate Theses and Dissertations

Biofiltration without pre-ozonation has the capability to remove natural organic matter (NOM) fractions that serve as precursors of disinfection byproducts (DBPs), which include the four regulated trihalomethanes (THMs) and dichloroacetonitrile (DCAN). Rapid small-scale column tests (RSSCTs) and Pilot Plant filters operated at empty-bed contact times (EBCTs) of 4, 8, and 16 minutes were used to evaluate the performance of nutrient-amended (free ammonia and phosphorus) biofiltration for THM and DCAN precursor removal, as measured using formation potential (FP) tests. NOM surrogates – which include dissolved organic carbon (DOC), specific ultraviolet absorbance (SUVA254) and fluorescence-PARAFAC components – were measured weekly throughout the …

Online Bioanalytical Mass Spectrometry Methods For Analysis Of Small And Large Biomolecules Using One- And Two-Dimensional Liquid Chromatography, Yehia Zakaria Baghdady

Chemistry & Biochemistry Dissertations - Archive

In recent years, the innovation in biomarkers and biotherapeutics has increased the demand for state-of-the-art analytical platforms to achieve reliable and accurate discoveries and quantitative analysis methods. The challenges in their determinations are not limited to the large number of small and large biomolecules but also involve the great heterogeneity in chemical properties and abundance of those analytes. Liquid chromatography and mass spectrometry have advanced significantly to be the most common platform for analyzing biological samples. However, there are still many unmet challenges that that require application of novel bioanalytical methods to fill many gaps in online sample preparation, chromatographic …

Fundamental Studies On Ultrafast Separations And Development Of Geopolymer Based Base-Stable Stationary Phase Media, Rasangi Madhumali Wimalasinghe K.K.D.G.

Chemistry & Biochemistry Dissertations - Archive

This thesis consists of two sections. In the first section fundamentals of ultrafast separations is discussed. Ultrafast chromatography is an emerging area of separation science due to its applicability in high-throughput separations and purifications. State of the art superficially porous particles packed short and ultrashort columns are utilized to obtain the amenable speed and chromatographic efficiency required in ultrafast chromatography. Modifications to state of the art HPLC and UHPLC instrumentation required in cases where ultrafast separations are needed. Sub-second liquid chromatographic separations and ultrafast separations of biomolecules and complex mixtures are demonstrated. Fundamentals behind the analytical chromatographic column packing are …

Oxidation Of Carbon Monoxide Over Ceria And Alumina Supported Palladium Catalysts, John Davis Gary

Theses and Dissertations

Palladium catalysts on both Al2O3 and CeO2, supports were studied for efficacy in low temperature carbon monoxide oxidation. Calcination temperatures were varied between 500-900°C for alumina supported catalysts and shown to have no significant difference in activity. X-Ray Photoelectron Spectroscopy studies revealed structural changes associated with palladium states and reacted catalysts and displayed a change from palladium oxide (PdO) to native palladium oxide (PdOx) and elemental palladium (Pd). Activity studies were conducted on all catalysts synthesized and indicated that Pd/Al2O3 achieved 100% CO conversion at 150°C when calcined at 500°C and pretreated with reduction process. Pd/CeO2 showed higher activity and …

Groundwater Hydrogeolgy And Hydrochemistry Of Karst Springs In The Eastern Peninsula Of Fort Hood Military Installation, William Scribner Welles

Electronic Theses and Dissertations

The eastern peninsula of Fort Hood Military Installation is underlain by a complex karst spring network. These springs are a primary water source in a protected habitat for endangered songbirds, which has only recently begun to be fully investigated. These Fredericksburg Group springs express both epigenetic and hypogenetic karst signatures. The study area is part of a paleo reef trend, a hydraulically disconnected segment of the northern section of the Edwards Aquifer. This study utilized standard ion index values, repeated measures, and principal component analyses on the chemical profiles of six perennial springs to classify spring water sources and their …

Diamond Intracrystalline Stable Isotope Chemical Image Analysis By Time-Of-Flight Secondary Ionization Mass Spectrometery, Tyler J. Sundell

Graduate Theses/Dissertations

The chemical resistance of diamond allows in-situ study of the diamond source regions. For a majority of gem quality diamonds, this source region is the sublithospheric mantle keel of a cratonic nuclei. Through analysis of stable isotopes, radiogenic isotopes and trace elements, diamond geochemical analyses can define chemical fluxes in the mantle keel. However, such studies require multiple methodologies for each chemical suite, high spatial resolution and analytical precision. Here, I evaluate Time-of-Flight Secondary Ionization Mass Spectrometer (ToF-SIMS) as an alternative method for diamond geochemical analyses. ToF-SIMS analysis can perform in cation and anion mode to measure the entire periodic …

Influence Of High Aspect Ratio Nanoparticle Filler Addition On Piezoelectric Nanocomposites, Jeremy A. Armas

Master's Theses

Piezoelectric nanogenerators (PNGs) are a new class of energy harvesting materials that show potential as a direct energy source for low powered electronics. Recently, piezoelectric polymers have been utilized for PNG technology due to low toxicity, high flexibility, and facile solution processing which provide manufacturing opportunities such as screen printing. Throughout the last decade, countless projects have focused on how to enhance the energy harvesting capabilities of these PNGs through the incorporation of nanoparticle fillers, which have been reported to enhance the piezoelectric properties of the film either directly through their intrinsic piezoelectric properties or through acting as surfaces for …

Cigarette Litter Leachates: A Statistical Study Of Elements In Freshwater And Saltwater, Cintly Guzman Hernandez

Honors Theses

Cigarette butts are the most common item found in coastal litter cleanups as approximately 4.5 trillion smoked cigarette butts are discarded into the environment every year. Cigarette butts can leach toxic heavy metals and nicotine along with other compounds from tobacco combustion. Past research in our lab has analyzed elements leached from cigarette butts into freshwater. The cigarette butts consisted of smoked and unsmoked butts that were soaked varying periods of time, and at different pH levels to identify the relationship of these variables to the amount of metal leached. The elements analyzed were Al, Ba, Cd, Cr, Cu, Fe, …

Mechanistic Study Of The Inhibition Of Rho Gtpase-Mediated Metastasis, Hope Gloria Umutesi

Chemistry & Biochemistry Dissertations - Archive

The Ras superfamily of small GTPases are monomeric proteins that bind guanine nucleotides, and regulate many cellular signaling pathways. They function as molecular switches by shuttling between active GTP-bound and inactive GDP-bound states. The Ras superfamily consists of its subfamilies including Ras and Rho GTPases. Ras and Rho GTPases function to regulate cellular growth, transformation, transport, motility, traffic, and adhesion. Small GTPases reactions often require regulators, such as guanine nucleotide exchange factors (GEFs) and GTPase Activating Proteins (GAPs). GEFs mediate fast release of GDP and allow loading with GTP while GAPs accelerate the GTP hydrolysis to GDP. Redox agents also …

Designing Thermally Stable Ionic Liquid Stationary Phases For Gas Chromatography And Examining Their Structure-Property Relationships, Rahul A. Patil

Chemistry & Biochemistry Dissertations - Archive

Ionic liquids are popular in diverse scientific applications because of their unique physicochemical properties. The physicochemical properties of ionic liquids can be “tuned” by the modification of their structural moieties. Understanding of structure-property relationship is important if one wants to introduce a desired property in ionic liquid for a specific application. The initial part of this thesis will discuss the understanding of structure-property relationship of dicationic ionic liquids. Ionic liquids with high thermal stability are useful in many applications from simple solvents for high temperature reactions to high vacuum lubricants for space applications. This thesis presents the design, synthesis, and …

Development Of Highly Polar Structurally-Tuned Ionic Liquids With Unique Selectivity For Gas Chromatography, Mohsen Talebi

Chemistry & Biochemistry Dissertations - Archive

Ionic Liquids (ILs) are state-of-the-art fluids that have found broad application in separation science. Owing to their unique physicochemical properties such as low vapor pressure, high thermal stability, and high viscosity, they were successfully used as stationary phase in gas chromatography (GC). By properly engineering their molecular structure, ionic liquids with tailor-made properties can be designed. Therefore, a systematic structure-function relationship can be established to study the effect of structural modification on the properties of ionic liquids. Herein, I describe the design and synthesis of several dicationic ionic liquids. The synthesized ILs were characterized in terms their physicochemical properties. The …

Sem/Edx Analysis Of Bronze Disease, Brian Pauley, Nicole Bishop

Fall 2018 - Chemical Analysis Class Projects

Bronze disease is a type of self-progressing corrosion of bronze. This degradation is thought to be caused by humidity but proliferated through the formation of chlorine containing compounds that further react with the air. The origination of the bronze disease in this artifact is thought to have arisen from the tanning process used in the surrounding leather. It is highly probable that potassium chloride was used in the tanning process, providing the initial chlorides that cause bronze disease. The damage that this corrosion can cause can destroy priceless artifacts. An understanding of the bronze disease structure and chemical composition is …

Ft-Mir-Atr Of Organic Residues From Inside Peruvian Sacrificial Jars, Warren Rouse, Dr. Joshua Sebree

Fall 2018 - Chemical Analysis Class Projects

This project used various solvents in an attempt to determine the identity of the contents of Peruvian jars to determine their purpose.

A Compositional Study Of The Uni Museum Benin Bronzes Using Scanning Electron Microscopy, Elizabeth Akers

Fall 2018 - Chemical Analysis Class Projects

In 1897, the British empire annexed the kingdom of Benin in present day Nigeria.1 Many cultural artifacts, including a large collection of bronze statues and plaques, were taken and distributed among major museums

• Due to their increased demand, many sellers began creating fake bronzes to sell to tourists and collectors alike

• Four Benin bronze artifacts were donated to the museum in 1968 and have been questioned in terms of authenticity based on qualitative analyses

The Characterization Of Leather Wwii Artifacts Using Gc/Ms And Raman Spectroscopy, Brice Houser

Fall 2018 - Chemical Analysis Class Projects

Many museums face the challenge of protecting artifacts from deterioration. This process is often hampered by the history of the artifact, which can introduce factors that start or speed up the process of deterioration. An example of this is the method used during WW II to preserve leather. Mink oil or other fatty substances are used to help preserve and soften leather. A major component of mink oil is palmitic acid.

1 This fatty acid may have reacted with the brass in the same way that the oils from the hand react with coins to make that distinctive metallic smell, …