Chemistry Commons^™

Applying The Diffusion Of Innovation Theory To Characterize Stem Faculty Attending Professional Development Programs, Dihua Xue

Department of Chemistry: Dissertations, Theses, and Student Research

Instructional practices in undergraduate STEM courses have been static for decades, with a primary focus on lecture. Over the last twenty years, extensive research on how people learn science has led to the development of innovative instructional strategies that have been shown to enhance students’ learning and interest. These in turn have led to calls to reform instructional practices in STEM fields at the undergraduate level. However, evidence shows that these research-based instructional strategies have largely not been incorporated into classes. The promotion of these new strategies has been mostly conducted through workshops. Although numerous studies have evaluated the impact …

Developing Functionalized Peroxide Precursors For The Synthesis Of Cyclic And Spirocyclic Ethers, Anna J. Diepenbrock

Department of Chemistry: Dissertations, Theses, and Student Research

There is increasing interest in the development of methods for the synthesis of oxetanes and spirocyclic oxetanes, a class of molecules of interest to chemists as they synthesize libraries of possible drug target scaffolds with tunable physiochemical and biological properties.^1,2 Although most ethers are prepared through reaction of nucleophilic oxygen with electrophilic carbon, this work explores new reagents and routes for the synthesis of spirocyclic oxetanes based upon an application of "umpolung" or polarity reversal involving attack of nucleophilic carbon on the electrophilic oxygen of a peroxide (Scheme 1). In this work, a 2-carbon peroxide synthon for reverse etherification …

Eigenstate–Specific Temperatures In Two–Level Paramagnetic Spin Lattices, Mark Masthay, Calley N. Eads, Amber N. Johnson, R. Gerald Keil, Phillip Miller, Ross E. Jones, Joe D. Mashburn, Harry B. Fannin

Chemistry Faculty Publications

Increasing interest in the thermodynamics of small and/or isolated systems, in combination with recent observations of negative temperatures of atoms in ultracold optical lattices, has stimulated the need for estimating the conventional, canonical temperature Tconvc of systems in equilibrium with heat baths using eigenstate-specific temperatures (ESTs). Four distinct ESTs—continuous canonical, discrete canonical, continuous microcanonical, and discrete microcanonical—are accordingly derived for two-level paramagnetic spin lattices (PSLs) in external magnetic fields. At large N, the four ESTs are intensive, equal to Tconvc, and obey all four laws of thermodynamics. In contrast, for N < 1000, the ESTs of most PSL eigenstates are non-intensive, differ from Tconvc, and violate each of the thermodynamic laws. Hence, in spite of their similarities to Tconvc at large N, the ESTs …

Ion Trajectory Simulations And Design Optimization Of Toroidal Ion Trap Mass Spectrometers, Jessica Marie Higgs

Theses and Dissertations

Ion traps can easily be miniaturized to become portable mass spectrometers. Trapped ions can be ejected by adjusting voltage settings of the radiofrequency (RF) signal applied to the electrodes. Several ion trap designs include the quadrupole ion trap (QIT), cylindrical ion trap (CIT), linear ion trap (LIT), rectilinear ion trap (RIT), toroidal ion trap, and cylindrical toroidal ion trap. Although toroidal ion traps are being used more widely in miniaturized mass spectrometers, there is a lack of fundamental understanding of how the toroidal electric field affects ion motion, and therefore, the ion trap's performance as a mass analyzer. Simulation programs …

Nucleobase Sublimation On Mammut Americanum Tusk Fragments, Joshua Prybil

Mastodon Tusk Project Posters

Many preservation attempts have been made on the tusk that the University of Northern Iowa acquired. Due to the poor preservation attempts a lot of damage has happened and has caused the tusk to be in a way of disrepair. The Carver grant is very keen on the future preservation of the tusk. The sublimation of nucleobases will be able to help guide the type of preservation methods used in order to preserve the nucleobases and possible DNA still in the tusk. The extraction of nucleobases will not only help with the future preservation of tusk but it will also …

Determination And Quantification Of Lead Content In Mammut Americanus Dentine Material By Anodic Stripping Voltammetry, Emma R. Shipley

Mastodon Tusk Project Posters

A 120,000-200,000 year old mastodon tusk of species Mammut americanus, recovered from Hampton, Iowa in 1933 (right) was tested for lead using a lead test from Home Depot.1 The lead test was returned positive, so Anodic Stripping Voltammetry (ASV) was undertaken to determine the concentration of lead in the dentine material of the tusk. The lead concentration is of interest because lead could affect both the health of the conservator and researchers and also inform about the diet of the mastodon. Tusk dentine material (left) functions similarly to human teeth, and studies have shown that 90% of lead in the …

Removal Of Varnish Layers Verifying With Uv-Vis Spectroscopy, Vaughn Koch, Treasure Divis

Mastodon Tusk Project Posters

According to the Roy J. Carver grant, one of the goals is to get the mastodon tusk back to its original state. The preservation methods have not been well documented, therefore determining what the best solvents to remove the different layers needs to be known. In order to do this, various solvents will be used and confirmed through UV-vis spectroscopy with a Diffuse Reflectance Accessory (DRA) attached. This will measure the percentage of light that gets reflected back towards the detector. The image to the left shows the various layers that have been used in preserving the tusk, including some …

Quantitative Evaluation Of Heavy Metals In The Mastodon Tusk Ivory By Atomic Absorption Spectroscopy, Dmytro V. Kravchuck, Linda L. Wilson

Mastodon Tusk Project Posters

One of the most important objects in the University of Northern Iowa Museum collection is the Mammut Americanum (American Mastodon) tusk, which was originally found in 1933 in a sand pit south of Hampton, Iowa. Since then, severe mechanical and chemical damage was done to the tusk in attempts of restoration and storage, as shown in Figure 1. In order to address these problems, the UNI Museum was awarded a Roy J. Carver Charitable Trust Grant to restore and preserve the American Mastodon tusk. The purpose of the project is quantitative determination of the heavy metal content in the core …

Classification Of Tusk Layers By Means Of Raman Spectroscopy, Treasure Divis, Vaughn Koch

Mastodon Tusk Project Posters

The American Mastodon tusk was donated to the University of Northern Iowa, and Dr. J. Cable took the lead on preserving it for museum display at UNI. Dr. Cable’s notes stated that it would be possible to preserve the entire tusk, because the outside was “covered with a hard enamel-like substance”. Some notes were taken as to what materials were used to preserve the tusk early on, but their exact composition was not noted.

• Glazed and varnished between 1933 and 1960

• 1960 – canned patching plaster on chipping areas, glazing liquid (brown), two coats of varnish (satin finish …

What Is The Red Plaster In The Mastodon Tusk?, Tray Hickie

Mastodon Tusk Project Posters

During the first visit to the tusk, Dr. Sebree found the crack that had been filled with a strange plaster that was not known at the time.

After seeing the plaster glow from the small flashlight Dr. Sebree had with him, identifying this material seemed like an interesting project.

Due to the fact that the plaster’s makeup is unknown, but identifying the material it was made of, future attempts to restore and preserve the fossil can be done more safely in the event that the material is harmful

Initial x-ray analysis of the mastodon tusk revealed many unexpected surprises.

In …

Carbonization Studies On Mammut Americanum Tusk, Nina Jocic

Mastodon Tusk Project Posters

Many preservation attempts have been made on the tusk that the University of Northern Iowa acquired. Due to the poor preservation attempts a lot of damage has happened and has caused the tusk to be in a way of disrepair. The Carver grant is very keen on the future preservation of the tusk. The sublimation of nucleobases will be able to help guide the type of preservation methods used in order to preserve the nucleobases and possible DNA still in the tusk. The extraction of nucleobases will not only help with the future preservation of tusk but it will also …

Fluorescent Surface Mapping Of Mastodon Tusk, Clare Laubenthal, Joshua Sebree

Mastodon Tusk Project Posters

The subject of study is a Mammut americanum (American Mastodon) tusk. The tusk is currently damaged and in need of repair. To better understand the tusk and the preservation materials previously used, fluorescence spectrometry was used to make a surface map of the tusk. This data will be useful to the conservationists as they plan the care and restoration of the tusk.

An In Between Study: The Usage Of Cross-Sectional Sem And Raman Spectroscopy To Map The Surface Interfacing Of A Mastodon Tusk And Its Lacquers, Katherine Plotzke

Mastodon Tusk Project Posters

A microscopy study utilizing a DXR2 SmartRaman and Evex Mini-Scanning Electron Microscope (SEM) was done on the UNI Museum’s Mammut americanum (American Mastodon) tusk. A map of the surface interfacing was generated and provided information about the elemental composition and layer interconnectedness. Additionally, this project will also aid in the future restoration work on the tusk funded by the Roy J. Carver Charitable Trust.

Sem Topology Of Enamel, Tami Wallin

Mastodon Tusk Project Posters

The topology of the enamel is an important topic to study how, on a microscopic level, the surface of the tusk is rough or smooth so that the correct restoration material and method are applied to the tusk. The method of study to find this information will be the SEM; which with the back scattered electrons will tell me the topography and chemical composition on the surface of the mastodon tusk fragment that will be tested, shown in the image below. SEM has better spacial resolution than optical microscopes do with the measuring tool provided by the program and the …

The Warning On Saturated Fat: From Defective Experiments To Defective Guidelines, Fabian M. Dayrit

Chemistry Faculty Publications

Coconut oil has been adversely affected by the current dietary guidelines that advocate a lowering of total fat and the replacement of saturated fat with polyunsaturated fat. This recommendation has its origins in the saturated fat-cholesterol-heart disease hypothesis that Ancel Keys first proposed in 1957. This hypothesis became an official recommendation with the publication of the Dietary Guidelines for Americans in 1980 and has been adopted by many other countries and international agencies. The dietary recommendations also warn against coconut oil. Recently, the American Heart Association re-issued this warning in its 2017 Presidential Advisory. However, a critical review of the …

Developmental Steroids And Vitamins: Identified And Quantified In Predatory Lady Beetles, Andrea Hixson

Honors Theses

Autumn brings ladybeetles into homes to seek shelter during the winter, which is a nuisance. Their bites may induce an allergic reaction resulting in painful rashes. Predatory ladybeetles have been used as a biological control agents. Not only do they feed on ecological pests, they also feed on the saps of ripe fruits reducing the value of the damaged crop. Two species of ladybeetles (Coleoptera: Coccinellidae) will be examined to determine the quantities of steroids and vitamins used throughout their life stages. The species examined are native, Hippodamia convergens, of North America, and an invasive, Harmonia axyridis, of Asia. The …

Air-Processed Polymer Photovoltaics: Advanced Morphological Characterization And Synthesis Of New Materials For Increased Light Absorption, Levi Moore

Dissertations

Organic photovoltaics (OPVs) have undergone intense development in recent years due to their potential to produce inexpensive, flexible, lightweight, and portable solar cells utilizing organic photoactive materials. Polymer-based OPVs have recently surpassed the 10 % in laboratory-scale devices, but require strict processing conditions in inert environments. Materials and processing methods that are workable in air are therefore desired. In addition to the light-absorbing and charge transport properties of the active layer materials, the morphology, crystallinity and orientation of the components of the phase-separated blend are paramount in determining OPV device performance This dissertation explores the processing of the model polymer …

Ab Initio Structural Studies Of Cyclobutylmethyl Cations: Effect Of Fluoroalkyl Groups On The Relative Stability Of The Carbocations, Prakash Reddy, Golam Rasul, G. K. Surya Prakash

Chemistry Faculty Research & Creative Works

Ab initio calculations at MP2/cc-pVTZ level show that the trifluoromethyl group has a strong destabilizing effect on the nonclassical, σ-bridged cyclobutylmethyl cations. The GIAO-MP2 derived ¹³C NMR chemical shifts indicate substantial charge delocalization from the neighboring cyclobutyl ring for carbocations with an α-fluorolkyl group as compared to the 1-cyclobutylethyl cation, and this enhanced charge delocalization in case of the α-(trifluoromethyl)cyclobutylmethyl cation would lead to the ring-opening rearrangement to form the relatively more stable nonclassical primary cyclobutylmethyl cation, in which the carbocation center is farthest from the strongly electron-withdrawing trifluoromethyl group.

Identification Of Aspergillus Fumigatus Udp-Galactopyranose Mutase Inhibitors, Julia S.Martin Del Campo, Meital Eckshtain-Levi, Nancy J. Vogelaar, Pablo Sobrado

Chemistry Faculty Research & Creative Works

Aspergillus fumigatus is an opportunistic human pathogen responsible for deadly, invasive infections in immunocompromised patients. The A. fumigatus cell wall is a complex network of polysaccharides among them galactofuran, which is absent in humans. UDP-galactopyranose mutase (UGM) catalyzes the conversion of UDP-galactofuranose (UDP-Galf) to UDP-galactopyranose (UDP-Galp) and is an important virulence factor. UGM is a flavin-dependent enzyme that requires the reduced flavin for activity; flavin reduction is achieved by reaction with NADPH. The aim of this work was to discover inhibitors of UGM by targeting the NADPH binding site using an ADP-TAMRA probe in a high-throughput screening assay. The flavonoids …

Oxidation Of Dibenzothiophene To Dibenzothiophene-Sufone Using A Molybdenum (Vi) Oxide Catalyst: A Kinetic Study Testing Solvent Dependency And Mole Ratio Efficiency, Tomas Trevino Jr.

Theses and Dissertations

Oxidative desulfurization (ODS) is currently a solution to hydrodesulphurization. Currently, industrial usage of hydrodesulphurization (HDS) is the common source for petroleum purification. Unfortunately, HDS comes with environmental and economical ramifications. Due to the problems and potential hazards being presented with HDS, ODS has become a topic of interest in research development. A kinetic study using molybdenum (VI) oxide as a catalyst was used in oxidative desulfurization. Factors such as mole ratio and solvent dependency were tested for efficiency. As activation energy was calculated to show maximum efficiency with respect to temperature and concentration. Gas Chromatography, FT-IR, and Mass Spectroscopy were …

Remediation Of Lead And Copper Ions From Water Solutions Using Transition Metal Sulfides, Jesus M. Cantu Jr.

Theses and Dissertations

Heavy metal contamination in water solutions has been a major concern since many transition metals don’t play a role in any biological function and are actually detrimental to human health. There have been several techniques that have been implemented for the remediation of heavy metal contaminants. For this project, three metal sulfides—Fe7S8, ZnS, TiS 2—were synthesized and studied for their capabilities to remove Pb(II) and Cu(II) from water solutions. Several parameters were investigated to determine the effects of pH, time, temperature, binding capacities, and interfering ions. The room temperature adsorption capacities ranged 6.23–333.3 mg/g for Pb(II) and 1.31–250 mg/g for …

Remediation Of Trivalent And Hexavalent Chromium Ions From Aqueous Solutions Using Titanium Dioxide Polymorphs, Yvette Cantu

Theses and Dissertations

Three titanium dioxide (TiO2) polymorphs were synthesized and used for the removal of chromium (III) and chromium (VI) from aqueous solutions. Various solution parameters were studied to determine the effects of pH, temperature, time, possible interfering ions, and capacities on the binding of Cr(III) and Cr(VI) to all three polymorphs. pH assays determined the optimum pH for the binding of both Cr(III) and Cr(VI) to each polymorph. Adsorption isotherms determined that the adsorption of Cr(III) was non-spontaneous for the three polymorphs with ΔG values ranging from 6.03 to 12.89 kJ/mol. Furthermore, the binding of Cr(VI) to anatase was also non-spontaneous …

Synthesis Of Tetraethyl ((2-Amino-1,4-Phenylene)Bis(Methylene)) Bis(Phosphonate): An Intermediate In The Synthesis Of Amino-Substituted Conjugated Materials, Ariel Ivan Torres Burgueno

Theses and Dissertations

Discussed here are the syntheses of the phosphonate precursors for the Wittig-Horner synthesis of poly-phenylene vinylene (PPV) and distyrylbenzene (DSB) derivatives and their respective distyrylbenzene analogs containing amino moieties. The synthesis of the different compounds was achieved through bromination, Michaelis-Arbuzov reaction, reduction of the nitro group with a commercial cobalt sulfide catalyst and sodium borohydride. Preliminary evidence for the synthesis of amino substituted distyrylbenzene and of nitro/alkoxy substituted poly(p-phenylene vinylene) was obtained. Characterization of the products was performed by 1H-NMR. Preliminary results of the synthesis of a novel amino-substituted distyrylbenzene (DSB) are presented. The luminescence of the new DSB was …

Hydrodesulfurization Of Dibenzothiophene Using Lanthanum Doped Comos2, Carolina Valdes Bracamontes

Theses and Dissertations

Hydrodesulfurization (HDS) is a technique used in petrochemical industry for the removal of sulfur from crude oil. Using dibenzothiophene (DBT) as a target molecule and CoMoS2 catalysts doped with various concentrations of lanthanum were studied for catalytic activity in the removal of DBT from solution. Catalysts were synthesized using ammonium tetrathiomolydate, cobalt chloride and lanthanum nitrate under a solvothermal decomposition in decalin at 350 °C with H2 gas at 160 psi. To evaluate decomposition effects, a second set of catalyst precursors were decomposed in a tube furnace at 450 °C under a constant flow of 10%/90% H2/Ar. Characterizations of the …

Capacity Of Human Immunodeficiency Virus Targeting Chimeric Antigen Receptor T Cells To Eliminate Follicular Dendritic Cells Bearing Human Immunodeficiency Virus Immune Complexes, Matthew T. Ollerton

Theses and Dissertations

An important obstacle to a functional cure for HIV/AIDS is the persistence of viral reservoirs found throughout the body in various cells and tissues. Reservoirs can be latently infected cells, or in the case of follicular dendritic cells (FDC), non-infected cells that trap infectious virus on their surface through immune complexes (HIV-IC). Although several strategies have been employed to target and eliminate viral reservoirs, they are short-lived and ineffective. In an attempt to provide a long-term approach, chimeric antigen receptor T (CAR-T) cells were designed to eliminate native HIV on FDCs. Although effective at eliminating HIV-infected cells, and halting spreading …

Evaluating Ligand Assisted Activation Of Small Molecules Through Proton Reduction And Alcohol Oxidation., Rahul Jain

Electronic Theses and Dissertations

Hydrogen is a potential alternate to the carbon fuels to meet the future demands for energy in an eco-friendly manner. Hydrogen produced by the electrolysis of water is stored in fuel cells which on demand can be converted into electrical energy upon the reaction with oxygen. In the quest for economically viable electrocatalysts for hydrogen evolution, the work in this dissertation describes evaluation of nickel based catalysts coordinated to redox active ligands, dialkyl/diarylphosphine benzenethiol and bis(thiosemicarbazone) for their ability to generate hydrogen with external acids as a proton source. A nickel complex with the benzenethiol ligand framework follows a traditional …

Development Of An Improved Synthesis Of S-D-Ribosyl-L-Homocysteine (Srh) And Progress Toward Srh Analogs Modified At The C3 Position, Emily Rouse

Master's Theses

Quorum sensing is a system that facilitates bacteria turning on and off gene expression depending on population density. System 2 quorum sensing is utilized by both Gram positive and Gram negative bacteria, and the quorum sensing molecule used in this system is AI-2. AI-2 is biosynthesized by the enzyme LuxS from the precursor SRH. This thesis describes an improved synthesis of SRH through the exploration of different protecting group strategies. The knowledge gained from the improved synthesis of SRH is then applied toward the synthesis of SRH analogues with increased steric bulk installed through use of a stereoselective anti-Mannich reaction. …

Barrier Properties Of Polymer Nanocomposites With Graphene Oxide And Its Derivatives: Mechanism And Applications In Anticorrosive Coatings, Yidan Guan

Dissertations

Metallic devices made from steel or aluminum are subjected to deterioration by environmental contaminants over time. As one of the corrosion control methods, organic coatings show many advantages due to their low cost, versatility, decoration aesthetics and effective protections. Corrosion protection theories and failure modes of organic coatings are still not fully understood due to complicated interactions in the coating-metal-environment system, however, it is widely agreed that the barrier nature of polymeric materials towards aggressive species, such as oxygen, water, electrolyte, plays a key role. Improved barrier property of polymer nanocomposites (PNCs) with two-dimensional (2D) carbon filler, graphene and graphene …

Sem/Edx Chemical Composition Map Of Mastodon Tusk, Juliana Herran

Mastodon Tusk Project Posters

The goal of this project was to study one of the rarest objects in the collection of the UNI museum dating to the Aftonian or Yarmouth age (around 120,000 to 200,000 years old).

The tusk is 11 feet, 7.5 inches with a circumference at the proximal end of 2 feet, 2 inches.

There have been previous attempts of restoration of this tusk but there are not specific procedures on record that specify the materials or methods used during the restoration attempts with sufficient detail.

With the support of the Carver Grant awarded to the UNI museum, research teams containing students …

Energy-Dispersive X-Ray (Edx) Mapping Of Lead In Mastodon Tusk Using Sem, Nicholas Bonde, Katherine Plotzke

Mastodon Tusk Project Posters

The composition and location of lead within a prehistoric mastodon tusk was mapped using Energy Dispersive X-ray (EDX) spectroscopy analysis via a Scanning Electron Microscope (SEM). This analysis was intended to provide information on the distribution of lead throughout the tusk. Data collected from this analysis has provided insights into the sources of the lead.