Analytical Chemistry Commons^™

Anatomy Of Stem Teaching In American Universities: A Snapshot From A Large-Scale Observation Study, Marilyne Stains, Jordan Harshman, Megan K. Barker, Stephanie V. Chasteen, Renee Cole, Sue Ellen Dechenne-Peters, M. Kevin Eagan Jr., Joan M. Esson, Jennifer K. Knight, Frank A. Laski, Marc Levis-Fitzgerald, Christopher J. Lee, Stanley M. Lo, Lisa M. Mcdonnell, Timothy A. Mckay, Nicole Michelotti, Michael S. Palmer, Kathryn M. Plank, Tamara M. Rodela, Erin R. Sanders, Natalie G. Schimpf, Patricia M. Schulte, Michelle Smith, Mackenzie Stetzer, Jackie Stewart, Blaire Van Valkenburgh, Erin Vinson, Laura K. Weir, Paul J. Wendel, Lindsay B. Wheeler, Anna M. Young

Department of Chemistry: Faculty Publications

National and local initiatives focused on the transformation of STEM teaching in higher education have multiplied over the last decade. These initiatives often focus on measuring change in instructional practices, but it is difficult to monitor such change without a national picture of STEM educational practices, especially as characterized by common observational instruments. We characterized a snapshot of this landscape by conducting the first large scale observation-based study. We found that lecturing was prominent throughout the undergraduate STEM curriculum, even in classrooms with infrastructure designed to support active learning, indicating that further work is required to reform STEM education. Additionally, …

Reductive Cleavage Of Organic Peroxides By Iron Salts And Thiols, Anderw Olson, Abigail J. Jameson, Shiva K. Kyasa, Boone W. Evans, Patrick H. Dussault

Department of Chemistry: Faculty Publications

Despite the low bond strength of the oxygen− oxygen bond, organic peroxides are often surprisingly resistant to cleavage by nucleophiles and reductants. As a result, achieving decomposition under mild conditions can be challenging. Herein, we explore the reactivity of a selection of peroxides toward thiolates, phenyl selenide, Fe(II) salts, and iron thiolates. Peroxides activated by conjugation, strain, or stereoelectronics are rapidly cleaved at room temperature by thiolate anions, phenylselenide, or Fe(II) salts. Under the same conditions, unhindered dialkyl peroxides are only marginally reactive; hindered peroxides, including triacetone triperoxide and diacetone diperoxide (DADP), are inert. In contrast, all but the most …

The Secant Rate Of Corrosion: Correlating Observations Of The Uss Arizona Submerged In Pearl Harbor, Donald L. Johnson, Robert J. Deangelis, Dana J. Medlin, Jon E. Johnson, James D. Carr, David L. Conlin

Department of Chemistry: Faculty Publications

Contrary to previous linear projections of steel corrosion in seawater, analysis of an inert marker embedded in USS Arizona concretion since the 7 December 1941 attack on Pearl Harbor reveals evidence that the effective corrosion rate decreases with time. The secant rate of corrosion, or SRC correlation, derived from this discovery could have a significant impact on failure analysis investigations for concreted shipwrecks or underwater structures. The correlation yields a lower rate of metal thinning than predicted. Development of the correlation is described.

Study Of The Oxidation Kinetics Of Nitrite Ions By Potassium Ferrate(Vi), J. Carr, I. Goncharova, D. Golovko, C. Mclaughlin, I. Golovko, J. Erickson

Department of Chemistry: Faculty Publications

Вивчено кiнетику окиснення нiтрит до нiтрат йонiв калiй фератом(VI) в широкому дiапазонi рН, вiд нейтрального до лужного сере- довища. Проведено двi серiї кiнетичних експе- риментiв, заснованих на рiзних технологiях одержання калiй ферату(VI). В першiй серiї експериментiв кристалiчний калiй ферат(VI) отримували хiмiчним синтезом. В дiапазонi рН 6.5–11 твердий K₂FeO₄ додавали до роз- чинiв нiтрит йонiв при вiдомiй концентрацiї та рН. Експерименти проводили пiд контролем рН та йонної сили. Кiнетичнi дослiдження коливалися вiд мiлiсекунд до декiлькох хви- лин. В другiй серiї експериментiв розчини K₂FeO₄ було отримано електрохiмiчним син- тезом. Лужнi розчини калiй ферату(VI) в 8.0 М …

The Study Of The Degradation Of Hexabromocyclododecane In A Heterogeneous System Containing Fe(Ii) Adsorbed To The Iron Oxide Hematite., Kristian K. Roopnarine

Dissertations and Theses

The reaction of hexabromocyclododecane (HBCDD), a widely used brominated flame retardant, was studied in a heterogenous mixture containing reactive Fe(II) adsorbed to the iron oxide hematite. The adsorbed Fe(II)/iron oxide system has shown to be a potent reductant in the transformation of organic contaminants with relatively water soluble organic contaminants. There currently aren’t many studies involving hydrophobic organic contaminants, such as HBCDD, in this reducing Fe(II)/iron oxide system. The results indicate that across the pHs 6.86, 6.95, 7.15 and 7.35 γ and β-HBCDD are degraded within a couple days. The pseudo-first order rate constants at pH 6.95 are 0.049 hr …

Quantitation Without Calibration: Response Profile As An Indicator Of Target Amount, Mrittika Debnath

Graduate Research Theses & Dissertations

Quantitative assessment of biomarkers is essential in numerous contexts from decision-making in clinical situations to food quality monitoring to the interpretation of life-science research findings. However, appropriate quantitation techniques are not as widely addressed as detection methods. One of the major challenges in biomarker’s quantitation is the need to have a calibration for correlating a measured signal to a target amount. The step complicates the methodologies and makes them less sustainable. In this work, we addressed the issue via a new strategy: relying on the position of response profile rather than absolute signal for assessment of a target nucleic acid’s …

The Development Of A Simplified Alkalinity Titration Analyzer, Reba Van Beusekom

Graduate Student Theses, Dissertations, & Professional Papers

Alkalinity is the acid neutralizing capacity for water, meaning alkalinity measures how sensitive an aquatic system is to acidic inputs. Currently, there are various measuring systems for alkalinity available including chemical test kits, potentiometric techniques, and colorimetric methods. Commercially available products lack the ease of use combined with precision and accuracy desired for on-line process and environmental monitoring. The goal of this project is to develop a simplified alkalinity titration analyzer, called the easyTMT, to measure alkalinity with precision and accuracy comparable to the best conventional methods. The system, under development, uses the Tracer Monitored Titration (TMT) technique. TMT …

Plasmon-Enhanced Optical Sensing By Engineering Metallic Nanostructures, Peng Zheng

Graduate Theses, Dissertations, and Problem Reports (ETD)

The world’s booming population projected to reach 10 billion by 2050 causes enormous stresses on environmental safety, food supply, and healthcare, which in return threatens human civilizations. One of the most promising solutions lies at innovating point-of-care (POC) sensing technologies to conduct detection of environmental hazards, monitoring of food safety, and early diagnosis of diseases in a timely and accurate manner. The discovery of surface-enhanced spectroscopy in the 1970s has significantly stimulated research on light-matter interaction which gives rise to enhanced optical phenomena such as surface-enhanced Raman scattering (SERS), plasmon-enhanced fluorescence (PEF), and particularly, they have found enormous applications in …

Enhanced Analysis Of Lignin Dehydrogenation Oligomers Via Mass Spectrometry, Amber Suzanne Bowman

Theses and Dissertations--Chemistry

Effective analytical techniques need to be developed to characterize the products of lignin degradation experiments to be able to generate renewable products from lignin. Mass spectrometry is an valuable analytical approach for lignin characterizaion, but it is hindered by lignin’s poor ionization efficiency, especially in the positive ion mode. In this work, we attempt to improve lignin’s ionization by utilizing electrospray and laser desorption mass spectrometry coupled with the addition of cations and chemical derivatives. We confronted the ionization problem from both a top-down and bottom-up analytical approach by analyzing synthesized monomers, dimers, and polymers along with natural lignin extracts …

Applications Of Cell-Derived Vesicles: From Single Molecule Studies To Drug Delivery, Faruk H. Moonschi

Theses and Dissertations--Chemistry

Single molecule studies can provide information of biological molecules which otherwise is lost in ensemble studies. A wide variety of fluorescence-based techniques are utilized for single molecule studies. While these tools have been widely applied for imaging soluble proteins, single molecule studies of transmembrane proteins are much more complicated. A primary reason for this is that, unlike membrane proteins, soluble proteins can be easily isolated from the cellular environment. One approach to isolate membrane proteins into single molecule level involves a very low label expression of the protein in cells. However, cells generate background fluorescence leading to a very low …

Carbon Quantum Dots: Bridging The Gap Between Chemical Structure And Material Properties, Timothy J. Pillar-Little Jr.

Theses and Dissertations--Chemistry

Carbon quantum dots (CQDs) are the latest generation of carbon nanomaterials in applications where fullerenes, carbon nanotubes, and graphene are abundantly used. With several attractive properties such as tunable optical property, edge-functionalization, and defect-rich chemical structure, CQDs have the potential to revolutionize optoelectronics, electro- and photocatalysis, and biomedical applications. Chemical modifications through the addition of heteroatoms, chemical reduction, and surface passivation are found to alter the band gap, spectral position, and emission pathways of CQDs. Despite extensive studies, fundamental understanding of structure-property relationship remains unclear due to the inhomogeneity in chemical structure and a complex emission mechanism for CQDs.

This …

Catalytic Conversion Of Monosaccharides Into 5-(Hydroxymethyl)Furfural In Ionic Liquids Using Aluminum Complexes Bearing Bidentate (Aminomethyl)Phenolate Ligands, Daudi Sayialel Saang'onyo

Theses and Dissertations--Chemistry

Currently, the major sources of fuel, energy, and chemicals are nonrenewable fossil resources such as petroleum, natural gas, and coal. Additionally, petroleum is used for the production of most transportation fuels and for the production of about 95% of organic chemicals. However, the production and use of non-renewable fossil fuels are unsustainable. For economic and environmental sustainability, there is a need to search for new and/or renewable resources and technologies for energy, fuels, and chemicals production that have the potential of effectively substituting fossil resources. In this context, lignocellulosic biomass is one of the candidates that meet these requirements due …

Aqueous Photochemistry Of 2-Oxocarboxylic Acids, Alexis Eugene

Theses and Dissertations--Chemistry

Atmospheric aerosols affect climate change by altering the energy balance of the atmosphere, and public health due to their variable chemical composition, size, and shape. While the formation of secondary organic aerosol (SOA) from gas phase precursors is relatively well understood, it does not account for the abundance of SOA observed during field measurements. Recently it has become apparent that in-aerosol aqueous chemical reactions likely provide some of the missing sources of SOA production, and many studies of aqueous phase processes are underway.

This work explores the fates of the simplest 2-oxocarboxylic acids, glyoxylic acid (GA) and pyruvic acid (PA), …

Evaluation Of Autonomously Measured Alkalinity, Ph, And Pco2 Variability On A Coral Reef, Brittany Peterson

Graduate Student Theses, Dissertations, & Professional Papers

Currently, our understanding of alkalinity (A_T) variability in highly dynamic environments such as coral reefs is limited by the dearth of A_T measurements. In order to better characterize these environments, high temporal resolution A_T data are needed. This work employed the newly developed Submersible Autonomous Moored Instrument for Alkalinity (SAMI-alk), a fully autonomous in situ A_T analyzer, to study seawater A_T variability. The main goals of this research were to evaluate the utility of combining the SAMI-alk data with currently available in situ measurements of pH and partial pressure of carbon dioxide (p …

Relationships Among Vitamin D Deficiency, Metabolic Syndrome, Smoking Behavior, And Physical Activity, Ethan Pham

Walden Dissertations and Doctoral Studies

Aging increases the risk of both vitamin D deficiency and metabolic syndrome. Vitamin D deficiency and metabolic syndrome may be related, although there are mixed findings. Furthermore, literature suggests other factors such as physical fitness activity and smoking behavior are associated with Vitamin D deficiency and the development of metabolic syndrome. A number of studies have documented associations between Vitamin D levels and physical fitness activities, while other studies found correlations between Vitamin D levels, metabolic syndrome, and smoking behavior. However, no previous study has examined the links between physical fitness activity, smoking behavior, Vitamin D levels, and the risks …

Part I: Design, Synthesis, And Studies Of Novel Age-Inhibitors And Age-Breakers; Part Ii: Novel Synthetic Methods For Organofluorine Compound, Jatin Mehta

Doctoral Dissertations

"Novel small molecule inhibitors and breakers of advanced glycation end-products (AGEs) have been synthesized and their in vitro inhibitory activities have been studied by ¹³C NMR, fluorescence, and UV-visible spectroscopy. We have demonstrated that these AGE-inhibitors and AGE-breakers were found to be more effective in their sequestration of AGE intermediates, such as dehydroascorbate (DHA) than the state-of-the art phenacylthiazolium bromide (PTB)-based AGE-inhibitors and AGE-breakers. Citric acid and other polyphenolic antioxidants have substantial AGE inhibitory effects in the D-glucose/leucine or benzylamine Maillard reaction model systems, and thus they are suitable as dietary additives for ameliorating AGE-induced complications.

Organofluorine compounds have …

Heteroatom Doped Porous Carbon For Alternative Energy Conversion And Storage Systems, Fatema A. Choudhury

Theses and Dissertations

Abstract

The electrocatalysis of oxygen plays a significant role in several electrochemical energy storage and conversion systems including metal−air batteries, fuel cells, electrocatalytic and photocatalytic water splitting. The sluggish kinetics and complex reaction mechanism of this cathodic oxygen reduction reaction (ORR) affect the performance and practical application of such renewable energy technologies. To address this limiting factor, a suitable electrocatalyst is required for ORR. In general, platinum or highly dispersed Pt-based nanoparticles on carbon black are considered as the best ORR catalyst. But platinum being very scarce and expensive tends to increase the cost. Moreover, platinum-based catalysts are prone to …

Development, Manufacture And Application Of A Solid-State Ph Sensor Using Ruthenium Oxide, Wade Lonsdale

Theses: Doctorates and Masters

The measurement of pH is undertaken frequently in numerous settings for many applications. The common glass pH probe is almost ideal for measuring pH, and as such, it is used almost ubiquitously. However, glass is not ideal for all applications due to its relatively large size, fragility, need for recalibration and wet-storage. Therefore, much research has been undertaken on the use of metal oxides as an alternative for the measurement of pH.

Here, a solid-state potentiometric pH sensor is developed using ruthenium metal oxide (RuO2). Initially, pH sensitive RuO2 electrodes were prepared by deposition with radio frequency magnetron sputtering (RFMS) …

Detection Of Cyanotoxins (Microcystins/Nodularins) In Hepatic Tissues And Epidermal Mats Of Stranded Bottlenose Dolphins (Tursiops Truncatus) In Northeast Florida, Amber Brown

UNF Graduate Theses and Dissertations

The St. Johns River (SJR; Jacksonville, FL, USA) is a large, brackish, estuarine system characterized by considerable anthropogenic pollution, recurrent harmful algal blooms (HABs), and diverse toxin-producing cyanobacteria. The most prevalent toxins in SJR water samples are microcystins/nodularins (MCs/NODs). Additionally, the SJR provides critical habitat for a genetically and behaviorally distinct estuarine community of bottlenose dolphins (Tursiops truncatus) that routinely uses and strands in low mesohaline and oligohaline areas of the river. This population has been subject to two unusual mortality events (UME) since 2010 and has since been described as having substantial declines in population health, characterized …