Chemistry Commons^™

3d-Printed Structured-Illumination Neutron Optics For Phase Contrast Imaging With A Triga Neutron Source, Bridget Cadigan

Honors Capstones

No abstract provided.

In Situ Plant Uptake Of Excess Nutrients And Consequential Alteration Of Rhizosphere Dynamics, Srusti Maddala

Crop, Soil and Environmental Sciences Undergraduate Honors Theses

The use of phytoremediation in ecological remediation projects has numerous benefits including soil stabilization and nutrient uptake. Recently, microdialysis, a diffusion-based sampling technique commonly used in biomedical research, has been recognized as a candidate for monitoring chemical changes in the rhizosphere. The real-time, in situ data it provides about nutrient diffusion may improve the management and success of restoration projects. Therefore, the objective of this study was to employ the technique of microdialysis in the novel application of quantifying the diffusive flux of inorganic nitrogen compounds in the rhizosphere of native plants of Arkansas. The microdialysis technique was first optimized …

A Study And Synthesis : Bronze Compounds, Patricia Rose Olsen

Theses, Dissertations and Culminating Projects

The focus of this thesis is the investigation of ternary and quaternary reduced metal oxide compounds termed “bronzes.” The name bronze originally arose from the metallic-like luster of these compounds. Examples of these compounds range from sodium tungsten oxides to the more complex potassium cesium molybdenum oxides. These compounds are crystalline solids at room temperature.

The “bronzes” are compounds that have been studied since their initial synthesis by Wohler in 1824. These compounds belong to a class of compounds that are known as “nonstoichiometric” compounds. The general formula for reduced ternary transition metal oxides is AxMyOz. In this general formula, …

Discovery Of Single-Stranded Dna Aptamers For The Detection Of Ranavirus, Allyssa Angel

Theses, Dissertations and Culminating Projects

A key problem when developing molecular diagnostic techniques is procuring target detection probes. The need of a stable and selective probe is necessary for accurate target identification in disease detection. Antibodies are widely used but they are unstable at ambient temperatures and are expensive and time consuming to develop. The use of aptamers (short singlestranded DNA) as molecular probes provides several advantages over protein-based methods because they are more stable, easily selected and modifiable. The need of a reliable and stable probe is necessary for accurate detection tests in the field for disease monitoring. Currently, field methods are limited in …

Determining Donor Age Through Blood Analysis Using Attenuated Total Reflection Fourier Transform-Infrared (Atr Ft-Ir) Spectroscopy For Forensic Purposes, Samantha Leigh Giuliano

Legacy Theses & Dissertations (2009 - 2024)

Chapter 1 of this thesis is an overview of the use of attenuated total reflection Fourier transform-infrared (ATR FT-IR) spectroscopy in industry and for examination of body fluids with emphasizes on examination of blood. It covers recent developments for analysis of samples with ATR FT-IR spectroscopy for forensic purposes.

Hplc Detection Of Organic Gunshot Residues With Silicone Wristbands, Yelyzaveta Zuy

Honors Theses

The analysis of gunshot residue (GSR) is frequently used to aid in investigating firearm-related crimes. Typically, Scanning Electron Microscopy (SEM) is applied for inorganic analysis of elements such as lead, barium, and antimony to study GSR. However, heavy metal-free ammunition creates the need for a different type of approach. This research focuses on studying the potential of detecting organic gunshot residue (OGSR) collected with silicone wristbands through passive sampling. This study has been directed towards the development of an optimal High Performance Liquid Chromatography (HPLC) procedure for the detection and separation of five selected compounds typically found in OGSR. The …

Enhancing Upconversion Nanoparticle Performance Of Nayf4: Yb,Tm With Doping Optimization And Shell Addition And Of Nayf4: Yb,Er With Yb,Nd Shell Addition, Ashleigh M. Chov

Honors Thesis

Upconversion (UC), is a phenomenon that occurs when low-energy excitation (usually near-infrared (NIR)) results in higher-energy emission. Upconversion nanoparticles (UCNPs) are particles less than 100 nm in size that are synthesized using rare earth metals such as Yb, Er, Tm, and Y. UCNPs have important applications in a variety of fields, including bio-imaging, security printing, and latent fingerprint development. Traditional methods for latent fingerprint development such as fluorescent powder dusting have several drawbacks including low contrast, high background interference, and autofluorescence. NIR-to-NIR UCNPs are composed of NaYF₄: Yb, Tm and emit 800 nm light under 980 nm excitation …

Discriminating Azo Dyes: Conjugated Polymers, The Inner Filter Effect, And Array Sensors, Erin Crater

Honors Theses

Azo dyes are abundant pollutants that contaminate water supplies and threaten humans, biota, and ecosystem health. Their detection and discrimination are an incredible challenge due to the structural, chemical, and optical similarities between dyes, the complexity of the wastewater environment in which they are found, and their low environmental concentrations. In this work, the inner filter effect (IFE), combined with conjugated polymer array-based sensing, is utilized for the quantitative profiling of these pollutants. The array was constructed using three fluorescent, anionic conjugated polyelectrolytes whose varying spectroscopic properties led to distinct IFE patterns in the presence of the dyes. The unique …

Understanding Ice Mixtures Under Pluto Simulated Conditions And Their Implications For Geophysical Processes, Caitlin Joannah Ahrens

Graduate Theses and Dissertations

New Horizons at Pluto has given the planetary science community the first images of Pluto’s surface, including geologic wonders and compositional variability. Methane, nitrogen, and carbon monoxide make up the bulk of the volatile plutonian surface along with water ice. In this work, these three main volatiles are specifically investigated in the laboratory setting to understand the spectral properties and behavior of binary and ternary mixtures. The spectra are taken in the near-infrared wavelengths (1 – 2.5 µm) using Fourier transform infrared (FTIR) spectroscopy techniques utilizing the Pluto Simulation Chamber housed at the University of Arkansas, which can reach conditions …

Investigation On The Morphology Of Charge-Transfer Complexes In Low Density Polyethylene, Wade Korf

Master's Theses

Fillers are used ubiquitously throughout the fields of polymer and material science to overcome many inherent limitations to polymeric materials (i.e. poor stiffness or strength) and to expand their potential applications. There is a need to develop controllable particle architectures to better understand fundamental structure-property relationships in particle reinforced polymer composites. Charge-transfer complexes (CTCs) can assemble in situ into various needle and dendritic shapes via simple fabrication processes and at low loading levels. In this study, the effect of tetrathiafulvalene (TTF) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) CTC crystallites of various shapes and sizes on composite mechanical properties was investigated in an LDPE …

Thiol-Ene Click Chemistry For Solid State Triplet-Triplet Annihilation Upconversion And Parts-Per-Billion Pyrophosphate Sensing In Artificial Seawater, Abagail K. Williams

Master's Theses

Thiol-ene click chemistry is a robust approach to molecularly engineering polymers for many applications. Within this work, thiol-ene click chemistry is used to fabricate thiol-ene networks for TTA-UC and to synthesize a conjugated polyelectrolyte (CPE) used as a pyrophosphate (PPi) sensor in complex aqueous media. Chapter I focuses on the synthesis and upconversion performance of rubbery networks fabricated using thiol-ene click photopolymerization. The advancement of triplet-triplet annihilation based upconversion (TTA-UC) in emerging technologies necessitates the development of solid-state systems that are readily accessible and broadly applicable. We demonstrate that thiol-ene click chemistry can be used as a facile cure-on-demand synthetic …

Electrochemical Reduction Of Carbon Dioxide And Carbon Monoxide For The Production Of Green Fuels And Chemicals., Jacob M. Strain

Electronic Theses and Dissertations

It has become apparent that closing the carbon cycle on this planet in order to mitigate disastrous consequences of runaway global warming has become one of the most pressing issues of our civilization. One of the ways we need to accomplish this goal is by finding news methods to generate fuels that will be carbon neutral. Renewable fuels and green chemicals will be a major component of closing the carbon cycle and restoring our planet’s ecosystem into a sense of balance. A method that can help achieve this goal is the reduction of CO₂. If CO₂ can …

Computational Modeling Of Photolysis And Catalysis Reactions In Vitamin B12-Dependent Enzymes., Abdullah Al Mamun

Electronic Theses and Dissertations

Vitamin B₁₂ is a complex organometallic molecule, the derivatives of which such as adenosylcobalamin (AdoCbl) and methylcobalamin (CH₃Cbl) act as a cofactor in numerous enzymatic reactions. These two biologically active cofactors contain a unique organometallic Co-C σ bond. Important feature of this Co-C bond is that it can be activated by both thermally and photolytically inside the enzymatic environment as well as in the solution. In the case of enzymatic reactions where AdoCbl molecule act as a cofactor, the cleavage of the Co-C bond constitutes the key catalytic step. The most intriguing features of this cleavage is …

Size-Dependent Inhibitory Effects Of Antibiotic Nanocarriers On Filamentation Of E. Coli, Preeyaporn Songkiatisak, Feng Ding, Pavan Kumar Cherukuri, Xiao-Hong Nancy Xu

Chemistry & Biochemistry Faculty Publications

Multidrug membrane transporters exist in both prokaryotic and eukaryotic cells and cause multidrug resistance (MDR), which results in an urgent need for new and more effective therapeutic agents. In this study, we used three different sized antibiotic nanocarriers to study their mode of action and their size-dependent inhibitory effects against Escherichia coli (E. coli). Antibiotic nanocarriers (AgMUNH–Oflx NPs) with 8.6 × 10², 9.4 × 10³ and 6.5 × 10⁵ Oflx molecules per nanoparticle (NP) were prepared by functionalizing Ag NPs (2.4 ± 0.7, 13.0 ± 3.1 and 92.6 ± 4.4 nm) with a monolayer …

Optimizing The Synthesis Of A Theranostic Rhodamine, Alessandra Maisielou Rivera, Jonathan Alexander, Nathaniel Garrison

Creative Activity and Research Day - CARD

Current designs for small molecule theranostics, which serve both a diagnostic and therapeutic role, often involve dyes linked to therapeutic agents through a cleavable, traceless linker. In order to facilitate the separation of the dye from the therapeutic in response to a biological or chemical stimulus, linkers must incorporate elements of molecular logic, increasing their complexity and the overall bulk of the small molecule theranostic. By combining the self-immolative molecular logic of the linker into the structure of the dye itself, we hope to create a series of smaller, more atom-economical theranostics. Rhodamine dyes, which naturally possess aromatic rings with …

Determining The Impact Of Double-Layer Formation On Electrostatic Dna Melting, Gayatri Raghu

Creative Activity and Research Day - CARD

Electrostatic melting is an electrochemical tool that can be used to analyze the stability of the DNA double helix, allowing for the detection of various mutations in double stranded DNA (dsDNA).1 Here we explore the effect of electrochemical double layer formation on the electrostatic melting of dsDNA in an effort to better understand the mechanism of the aforementioned category of melting. Previous studies from our lab have shown that electrostatic melting curves can be used to distinguish between duplexes that are fully complementary and duplexes that contain a single mismatch.2 Electrostatic melting is assumed to result from the electrostatic repulsion …

Development Of Hyperpolarizable Macrocyclic 13c-Probes For The Quantification Of Metals In Vivo, Holly Clancy

Creative Activity and Research Day - CARD

Numerous studies have shown correlations between various diseases, such as cancer and Alzheimer’s disease, and a change in the concentration of metals in tissues. Current blood analysis-based methods of metal quantification do not always provide a sense of metal concentration in tissue samples. With this work, we aim to develop a non-surgical method to quantify metal concentrations in human tissue. Hexadentate ligands such as ethylenediaminetetraacetic acid (EDTA) tagged with a 13C label at the carbonyl position have shown specific shifting of the carbonyl peak upon complexation with various metals via magnetic resonance spectroscopy (MRS). Additionally, these compounds have shown increased …

Temperature-Dependence Of Electrostatic Dna Melting, Jeffrey Taylor

Creative Activity and Research Day - CARD

Electrostatic melting is a recently developed electrochemical tool that can be used to interrogate DNA stability, allowing for discrimination of double-stranded DNA (dsDNA) by base-pair sequence or the presence of mismatches, deletions, and other mutations (1). This type of analysis has potential applications in point-of-care diagnostics. Here we explore the dependence of temperature and potential on the kinetics of electrostatic melting in an effort to better understand the mechanism. Previous studies, by another group, have shown that the potential at which electrostatic melting occurs decreases with temperature in the range 10 – 18 °C, i.e. the melting becomes easier at …

Synthesis Of Sultams From Vinyl Aziridines And 1,4-Diazabicyclo[2.2.2]Octane Bis(Sulfur Dioxide), John Gandara

Creative Activity and Research Day - CARD

Sultams are an important functional group found in medicinal compounds with anticancer and enzyme inhibition activity. Traditional methods for sultam synthesis often require harsh conditions and have limited substrate scope. This research focuses on developing a novel methodology for the production of sultams using DABSO (1,4-diazabicyclo[2.2.2]octane bis(sulfur dioxide)) and vinylic aziridines. Our synthetic strategy starts with a Corey-Chaykovsky epoxidation of cinnamaldehyde, followed by an epoxide-opening using sodium azide. The final vinylic aziridine is synthesized by mesylation and Staudinger reduction of the resulting azido alcohol. Reaction of this vinyl aziridine with DABSO may provide a new strategy for synthesizing sultams. Following …

Synthesis Of Self-Immolative Rhodamine Based Theranostic Agent, Jonathan Alexander, Alessandra Rivera, Nathaniel Garrison

Creative Activity and Research Day - CARD

Theranostic agents, a class of molecules that simultaneously serve both a diagnostic and therapeutic function, enable in vivo imaging for early diagnosis and targeted drug delivery within a single entity. Due to recent advances in the synthesis and photophysical properties of the rhodamine scaffold, rhodamine dyes present a promising new direction for theranostic research. Toward the goal of exploring rhodamine dyes as self-immolative prodrugs for theranostic applications, we have synthesized a rhodamine precursor via a telescoped radical bromination/hydrolysis. Upon completion of the full rhodamine synthesis, we will explore and optimize the kinetics of its “turn-on” fluorescence and drug release in …

Determining The Mechanical Properties Of The E. Coli Methionine Transporter, Kha Andy Tran

Creative Activity and Research Day - CARD

Adenosine Triphosphate Binding Cassette (ABC) transporters constitute a superfamily of active transporters embedded in the cellular membrane. They consist of two highly conserved nucleotide-binding subunits which bind and hydrolyze ATP, and two diverse transmembrane subunits which provide a pathway for the substrate to pass through the membrane. ABC transporters serve a broad range of vital functions. Various conditions like cystic fibrosis and Stargardt disease are caused by defunct ABC transporters, and certain medical complications like antibiotic drug resistance are linked to promiscuous ABC transporters. Despite the importance of these transporters in crucial biological processes, the mechanisms of many transporters are …

Towards The Development Of Redox-Responsive Eu(Iii) Complexes For Cancer Imaging, Matthew Derfus

Creative Activity and Research Day - CARD

Cancer cells display redox dysregulation and lowered cytosolic pH as a means to maintain their over-proliferation. The development of an approach to probe tissue redox state could potentially allow discrimination between healthy and cancerous tissues. Magnetic Resonance Imaging (MRI) is a non-invasive technique used in the diagnosis of a variety of pathologies. The high spatial resolution and its use of non-ionizing radiation make MRI an attractive technique for cancer screening and detection. The quality of an MR image can be further enhanced with the aid of contrast agents, the majority of which are Gd(III) complexes. Gd(III) complexes provide positive contrast …

Investigating The Mechanism Of The E.Coli Atp-Binding Cassette Transporter Metni, Matthew Foronda

Creative Activity and Research Day - CARD

Intracellular chemical homeostasis is vital for cell survival. A key component for the maintenance of this homeostasis is ABC (ATP-binding cassette) transporters. These highly-conserved transporters utilize the energy from ATP binding and hydrolysis to move a wide array of substrates against their chemical gradient. Mutations can lead to a variety of diseases including cystic fibrosis and drug-resistant tumors. In order to solve these issues, these transporters must be well-studied. This project focuses on the mechanism of the methionine importer MetNI in E. coli, a reliable model for many transporters. Using fluorescence anisotropy, the apo-form of the substrate-binding protein (SBP) was …

Probing The Oxidation Chemistry Of Dimethoxymethane, A Model Ome Fuel, Rory Mcclish

Creative Activity and Research Day - CARD

The threat posed by anthropogenic global warming, along with attached mitigation policies, drives the search for alternative fuels or additives; this search requires understanding the combustion chemistry of possible biofuel candidates. The low-temperature oxidation of a potential diesel fuel substitute, dimethoxymethane (DMM, m/z 76), is herein investigated at 500K, 600K, and 700K using synchrotron radiation coupled with multiplexed photoionization mass spectrometry at the Advanced Light Source within the Lawrence Berkeley National Laboratory. The experimental data is resolved in 3 dimensions: time, mass, and photon energy; this allows for identification, characterization, and quantification of primary products. Energetics calculations are carried out …

Ti2ctx Mxene-Based All-Optical Modulator, Jun Yi, Jie Li, Shuohan Huang, Longyu Hu, Lili Miao, Chujun Zhao, Shuangchun Wen, Vadym Mochalin, Apparao M. Rao

Chemistry Faculty Research & Creative Works

MXenes, a new class of 2D transition metal carbides, nitrides, and carbonitrides, have attracted much attention due to their outstanding properties. Here, we report the broadband spatial self-phase modulation of Ti₂CT_x MXene nanosheets dispersed in deionized water in the visible to near-infrared regime, highlighting the broadband nonlinear optical (NLO) response of Ti₂CT_x MXene. Using ultrafast pulsed laser excitation, the nonlinear refractive index n2 and the third-order nonlinear susceptibility (Formula presented.) of Ti₂CT_x MXene were measured to be ∼10−13 m2/W and ∼ 10−10 esu, respectively. Leveraging the large optical nonlinearity of Ti …

A Cascade Reaction Of Cinnamyl Azides With Acrylates Directly Generates Tetrahydro-Pyrrolo-Pyrazole Heterocycles, Angela S. Carlson, En Chih Liu, Joseph J. Topczewski

Chemistry Faculty Research & Creative Works

Developing reactions to generate complex and modular building blocks in a concise and direct fashion remains a contemporary synthetic challenge. This work describes a stereoselective cascade reaction between allylic azides and acrylates that directly generates tetrahydro-pyrrolo-pyrazole ring systems. These products contain up to four contiguous stereocenters, two of which may be tetrasubstituted carbon atoms attached to a nitrogen atom. Over 30 examples are provided with an average isolated yield of 71% (ranging from 40% to 94%). The reaction was easily scaled to use more than one gram of starting material, and the products can be readily diversified.

Improving Biodiesel Through Pyrolysis: Direct Dynamics Investigations Into Thermal Decomposition Of Methyl Linoleate, Michael Bakker

Graduate Theses/Dissertations

Dependence on petroleum and petrochemical products is unsustainable as it is both a finite resource and environmentally hazardous. Biodiesel is a proposed alternative, but has complications including possessing poor cold weather operability and lacking the ability to supplement other petrochemical products (e.g., ethylene, hexane, etc.) relied upon in society. Pyrolysis of biodiesel has demonstrated the formation of smaller hydrocarbons comprising many of these petrochemical products. Our aim is to computationally simulate the pyrolysis of methyl linoleate, the most prevalent component in biodiesel formed in the US (from soybean). We make use of unimolecular direct dynamics describing intramolecular processes, introducing Temperature …

Probing Nanoelectroporation And Resealing Of The Cell Membrane By The Entry Of Ca2+ And Ba2+ Ions, Wenfei Bo, Mantas Silkunas, Uma Mangalanathan, Vitalij Novickij, Maura Casciola, Iurii Semenov, Shu Xiao, Olga N. Pakhomova, Andrei G. Pakhomov

Bioelectrics Publications

The principal bioeffect of the nanosecond pulsed electric field (nsPEF) is a lasting cell membrane permeabilization, which is often attributed to the formation of nanometer-sized pores. Such pores may be too small for detection by the uptake of fluorescent dyes. We tested if Ca²⁺, Cd²⁺, Zn²⁺, and Ba²⁺ ions can be used as nanoporation markers. Time-lapse imaging was performed in CHO, BPAE, and HEK cells loaded with Fluo-4, Calbryte, or Fluo-8 dyes. Ca²⁺ and Ba²⁺ did not change fluorescence in intact cells, whereas their entry after nsPEF increased fluorescence within <1 ms. The threshold for one 300-ns pulse was at 1.5–2 kV/cm, much lower than >7 …

Recombinant Expression Of Preptin Analogs For Alanine Scanning Mutagenesis Of Residues 27-29, Tehgan N. Anguilm

Theses and Dissertations

The novel peptide preptin consists of 34 amino acid residues corresponding to Asp⁶⁹-Leu¹⁰² of proinsulin-like growth factor E-peptide. Preptin has been isolated from pancreatic beta cells, and it has been found to exhibit both metabolic and mitogenic activities. This makes preptin an attractive candidate to treat insulin-independent diabetes and osteoporosis. Alanine scanning mutagenesis was utilized to substitute an alanine for residues Trp²⁷, Arg²⁸, and Gln²⁹ of preptin in order to ultimately study the structure-activity relationship of these residues to preptin’s metabolic activity.

Chemical And Electronic Surface Structure Of Chalcopyrite-Based Thin Films For Solar Water Splitting, James C. Carter

UNLV Theses, Dissertations, Professional Papers, and Capstones

In recent years, various thin film solar devices have reached markedly high efficiencies on both the laboratory and large area scale. To further evaluate their potential, and help drive device optimization of efficient solar devices, a detailed understanding of the chemical and electronic structure of the surfaces and interfaces is required. It is these interfaces that play a pivotal role in dictating aspects of device performance. Chalcopyrite-based materials, such as Cu(In,Ga)S2 (CIGS) are regarded as one of the most promising absorber materials for use in highly efficient solar devices. In the context of photoelectrochemical (PEC) hydrogen generation, the tunability of …