Physical Sciences and Mathematics Commons^™

The Construction And Optimization On An Ion Mobility Spectrometer For The Analysis Of Explosives And Drugs, Hanh Tuyet Lai

FIU Electronic Theses and Dissertations

Today, over 15,000 Ion Mobility Spectrometry (IMS) analyzers are employed at worldwide security checkpoints to detect explosives and illicit drugs. Current portal IMS instruments and other electronic nose technologies detect explosives and drugs by analyzing samples containing the headspace air and loose particles residing on a surface. Canines can outperform these systems at sampling and detecting the low vapor pressure explosives and drugs, such as RDX, PETN, cocaine, and MDMA, because these biological detectors target the volatile signature compounds available in the headspace rather than the non-volatile parent compounds of explosives and drugs. In this dissertation research volatile signature compounds …

Improved Arene Fluorination Methodology For I(Iii) Salts, Bijia Wang, Linlin Qin, Kiel D. Neumann, Shriharsha Uppaluri, Ronald Cerny, Stephen G. Dimagno

Ronald Cerny Publications

The use of low polarity aromatic solvents (benzene or toluene) and/or the removal of inorganic salts results in dramatically improved yields of fluorinated arenes from diaryliodonium salts. This methodology is shown to “scale down” to the conditions used typically for radiotracer synthesis.

Explorations In Homeoviscous Adaptation And Mass Spectral Analysis Of Membrane Lipids, Michael Douglas Timmons

University of Kentucky Doctoral Dissertations

The focus of this dissertation is centered on the mass spectral analysis of lipids and changes occurring in keeping with the concept of homeoviscous adaptation [1]. Homeoviscous adaptation is the process of modification of membrane lipids in response to environmental stimuli [1]. Dissertation investigations applied this concept to prokaryotic and eukaryotic organisms, and expanded the perception of environmental factors from exogenous organic solvents to intracellular environment.

The field of lipidomics deals with the analysis of phospholipid and fatty acid components of membranes the changes that occur due to environmental stimuli and their biological significance [2-6]. The high sensitivity of mass …

Self-Assembled Heteroleptic Chiral Ligands, Asymmetric Catalyst Systems And Methods, James M. Takacs

Chemistry Department: Faculty Publications

A method of synthesizing a heteroleptic, multiple metal containing metallocyclic catalyst, particularly Suited for asymmetric catalysis, comprising combining a plurality of plural functional group-containing, monodentate ligands of complementary chirality, said plural functional groups being tethered to each other by tethers in the presence of a scaffold structural metal Ms or derivative thereof, wherein at least one functional group on each ligand combines to ligate M to form a bidentate, M_s centered ligand scaffold containing the remaining functional groups and combining said bidentate ligand scaffold with a catalytic metal M_c or derivative thereof whereby the remaining functional groups combine …

Corrosion Of Civil War Era Sub Marine Explorer—Part 2, Donald L. Johnson, James D. Carr, Brent M. Wilson, Larry E. Murphy, James P. Delgado

Chemistry Department: Faculty Publications

The Sub Marine Explorer was designed and built by Julius H. Kroehl, who was born in Prussia in 1820. After migrating to the United States in 1838 and becoming a citizen, he served in the Union Navy (United States Navy during the Civil War) as an underwater demolitions expert. He left the Navy in 1863 and began designing a “sub-marine” that would facilitate Union forces’ mine removal and obstruction clearance. At the end of the Civil War, he became an engineer for the Pacific Pearl Co., an organization interested in using the craft to recover pearls from deep sea oyster …

Corrosion Of Civil War Era Sub Marine Explorer—Part 1, Donald L. Johnson, James D. Carr, Brent M. Wilson, Larry E. Murphy, James P. Delgado

Chemistry Department: Faculty Publications

The Sub Marine Explorer is one of five submersibles (submarines) constructed prior to 1870 that have survived either in museums or as in situ archaeological sites around the world. Since 1869, the wreck of Explorer has emerged at low tide on the beach of Isla San Telmo, Archipiélago de las Perlas, Panama, located ~75 km southwest of Panama City in the Bay of Panama. In 2001, James Delgado visited the site. Locals described the wreck as a World War II-era Japanese midget submarine. Delgado consulted with Richard Wills, an expert on American Civil War submarines, and confirmed that the well-preserved …

Method For Monitoring The Stereoselectivity And Relative Rate Of Organic Chemical Reactions, David R. Berkowitz, Sangeeta Dey, Kannan R. Karukurichi, Weijun Shen

Chemistry Department: Faculty Publications

A method for monitoring the stereoselectivity of at least one organic chemical reaction and the relative rate of at least one organic chemical reaction, wherein the reaction produces a product that can exist as at least two stereoisomers, is provided herein. Also disclosed are methods for identifying and preparing catalysts for the above reactions.

Geochemical Investigation Of An Offshore Sewage Sludge Deposit, Barcelona, Catalonia, Spain, Michael A. Kruge, Albert Permanyer, Jordi Serra, Danlin Yu

Department of Earth and Environmental Studies Faculty Scholarship and Creative Works

For 20 years ending in the 1990’s the city of Barcelona discharged the products from a large primary sewage treatment plant directly into the Mediterranean Sea via underwater conduits. About ca. 3 million m³ of relict sewage sludge, rich in organic matter and heavy metals, has spread over an elongated area offshore, due to successive ruptures of the conduits. The use of the discharge pipes ceased, but he sludge deposit remains in place for the time being.

To understand the history and present state of the sludge deposit in advance of future remediation, a program of geophysical mapping, sampling, …

The Analysis Of Cyanide And Its Breakdown Products In Biological Samples, Brian A. Logue, Diane M. Hinkens, Steven I. Baskin, Gary A. Rockwood

Chemistry and Biochemistry Faculty Publications

Cyanide is a toxic chemical that may be introduced into living organisms as a result of natural processes and/or anthropogenic uses (legal or illicit). Exposure to cyanide can be verified by analysis of cyanide or one of its breakdown products from biological samples. This verification may be important for medical, law-enforcement, military, forensic, research, or veterinary purposes. This review will discuss current bioanalytical techniques used for the verification of cyanide exposure, identify common problems associated with the analysis of cyanide and its biological breakdown products, and briefly address the metabolism and toxicokinetics of cyanide and its breakdown products in biological …

A Bland–Altman Comparison Of The Lead Care® System And Inductively Coupled Plasma Mass Spectrometry For Detecting Low-Level Lead In Child Whole Blood Samples, Christina Sobin, Tanner Schaub, Natali Parisi, Eva De La Riva

Christina Sobin, Ph.D.

Chronic childhood lead exposure, yielding blood lead levels consistently below 10 μg/dL, remains a major public health concern. Low neurotoxic effect thresholds have not yet been established. Progress requires accurate, efficient, and cost-effective methods for testing large numbers of children. The LeadCare® System (LCS) may provide one ready option. The comparability of this system to the “gold standard” method of inductively coupled plasma mass spectrometry (ICP-MS) for the purpose of detecting blood lead levels below 10 μg/dL has not yet been examined. Paired blood samples from 177 children ages 5.2–12.8 years were tested with LCS and ICP-MS. Triplicate repeat tests …

Process For Preparation Of Conducting Polymers, Reuben D. Rieke

Chemistry Department: Faculty Publications

Methods of preparing conducting polymers and the conductive polymers prepared therefrom are provided. The method includes a) combining a monomer-metal complex together with a manganese (II) halide to provide a monomer-manga nese complex, and b) combining the monomer-manganese complex together with a metal catalyst to provide the conductive polymer. Electronic devices can be made using the polymers prepared as described herein.

Corrosion Of Steel Shipwrecks In The Marine Environment: Uss Arizona—Part 2, Donald L. Johnson, Brent M. Wilson, James D. Carr, Matthew A. Russell, Larry E. Murphy, David L. Conlin

Chemistry Department: Faculty Publications

This article is a continuation of Part 1 (October 2006 MP) on the USS Arizona hull. It discusses additional methods being investigated for use in determining corrosion rates with a minimal impact on the existing structure. Marine biofouling (concretion) has accumulated on the hull. Concretion samples have been studied using x-ray diffraction, environmental electron microscopy, and corrosion potential (E_corr) to characterize the relationship between concretion and the steel substrate. The data presented in this study confirm the viability of concretion analysis as a minimum-impact procedure to estimate the corrosion rate of mild steel in seawater.

Corrosion Of Steel Shipwreck In The Marine Environment: Uss Arizona—Part 1, Donald L. Johnson, Brent M. Wilson, James D. Carr, Matthew A. Russell, Larry E. Murphy, David L. Conlin

Chemistry Department: Faculty Publications

The USS Arizona has remained submerged in Pearl Harbor, Hawaii, since the Japanese attack on December 7, 1941. The ship presents a potential hazard from fuel oil still present in the ship’s hull. As an important factor in management decisions, the effect of corrosion after nearly 65 years is being studied to determine the integrity of the ship’s structure. Coupon samples from the hull revealed decreasing corrosion rates from ~1 to 3 mpy (0.03 to 0.08 mm/y) from just below the water surface to the mudline. This is about one-third of that expected in the absence of biofouling or concretion. …

Iron And Manganese Based Nanomaterials For The Removal Of Selenite And Selenate From Aqueous Solution, Christina Marie Gonzalez

Open Access Theses & Dissertations

Selenium, a naturally occurring element in the environment, is an essential nutrient for humans and animals. However, there is a narrow range between selenium deficiency and toxicity. Selenium in natural waters generally has a concentration of < 10 ppb (parts per billion); however, in the San Joaquin Valley of California concentrations of selenium ranging from 140 to 1400 ppb have been observed. Anthropogenic practices such as agricultural irrigation drainage, coal burning power plants, combustion of fossil fuels, and mining operations are increasing selenium concentrations in aqueous environments. Once in aqueous environments, selenium exists primarily as the two inorganic oxoanions selenite (SeO32-) and selenate (SeO42-). Both of these selenium oxoanions are known to bioaccumulate and can cause embryotoxic and teratogenic effects to waterfowl. There has been a variety of treatment technologies developed for remediation of both selenium oxoanions in water including bacterial reduction, membrane filtration, chemical reduction, reverse osmosis, and solar ponds. However, these treatment technologies are not cost efficient. In this study an alternative treatment technique known as adsorption was used with three synthetic nanomaterials consisting of an iron oxide, manganese oxide, and an iron/manganese oxide. The pH profiles, time dependencies, competitive anion effects, and adsorption isotherms were performed with each of the nanomaterials for both selenite and selenate. In addition, X-ray absorption spectroscopy (XAS) studies were performed to determine both the oxidation state and binding coordination of the selenium oxoanion binding to the nanomaterials.

The investigation revealed the non microwave-assisted and microwave-assisted synthetic Fe3O4 and Mn3O4 nanomaterials, as well as the non microwave-assisted synthetic MnFe2O4 nanomaterial had the phases of magnetite, hausmannite, and Jacobsite, while the grain sizes were 27, 25, 25, 34, and 27 nm, respectively. The optimal binding of selenium oxoanions for all nanomaterials examined was reached at pH 4. Both non microwave-assisted and microwave-assisted Fe3O4 …

A New Green Chemistry Method Based On Plant Extracts To Synthesize Gold Nanoparticles, Milka Odemariz Montes Castillo

Open Access Theses & Dissertations

Extraordinary chemical and physical properties exhibited by nanomaterials, as compared to their bulk counterparts, have made the area of nanotechnology a growing realm in the past three decades. It is the nanoscale size (from 1 to 100 nm) and the morphologies of nanomaterials that provide several properties and applications not possible for the same material in the bulk. Magnetic and optical properties, as well as surface reactivity are highly dependent on the size and morphology of the nanomaterial. Diverse nanomaterials are being widely used in molecular diagnostics as well as in medicine, electronic and optical devices. Among the most studied …

Study Of Pbdes In Wastewater, Water And Sludge Of El Paso Del Norte Border Region Using Sbse Td/Gc-Ms, Beatriz Adriana Rocha-Gutierrez

Open Access Theses & Dissertations

Polybrominated diphenyl ethers (PBDEs) are a group of brominated compounds widely used as flame retardants. PBDEs are structurally similar to polychlorinated biphenyls (PCBs), and appear to act similarly in the environment. Due to their persistence and lipophilicity, PBDEs are found to be bioaccumulated and biomagnified in the food chain. Current research in PBDEs is focused on their occurrences, concentration, fate and transport in the environment, and the impact in the ecosystem and human health. Since PBDEs are not regulated in the USA, large amounts of these harmful chemicals are being dumped indiscriminately into the drainage system. As a result, these …

Chromium(Iii/Vi) Binding To Magnetite (Fe3o4), Hausmannite (Mn3o4), And Jacobsite (Mnfe2o4) Nanomaterials, Jeffrey Edward Hernandez

Open Access Theses & Dissertations

Chromium is a very versatile metal that is used for many applications in the world. Two of the most common ions of chromium that occur naturally are Cr(III) and Cr(VI). These two oxidation states have very different heath effects in living organisms. Cr(III) is relatively non-toxic to living organisms; however, Cr(VI) is very toxic to most living organisms This study was conducted to find a simple and cost effective method to sequester these two common ionic species of chromium from sources of water that are adjacent to or that are affected by other water sources contaminated by these two ions. …

Sulfur K-Edge Photo-Fragmentation Of Ethylene Sulfide, Wayne C. Stolte, Gunnar Ohrwall

Chemistry and Biochemistry Faculty Research

We have investigated the photofragmentation properties of the three-membered ring heterocyclic molecule ethylene sulfide or thiirane, C₂H₄S, by time-of-flight mass spectroscopy. Positive ions have been collected as a function of photon energy around the S K ionization threshold. Branching ratios were derived for all detected ions, which are informative of the decay dynamics and photofragmentation patterns of the core-excited species. We present a new assignment of the spectral features around the S K-edge.

Two-Dimensional To Three-Dimensional Structural Transition Of Gold Cluster Au 10 During Soft Landing On Tio 2 Surface And Its Effect On Co Oxidation, Hui Li, Yong Pei, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

We investigate the possible structural transition of a planar Au₁₀ cluster during its soft landing on a TiO₂ (110) surface with or with no oxygen defects. The collision between the gold cluster and the oxide surface is simulated using the Car–Parrinello quantum molecular dynamics method. Both high-speed and low-speed conditions typically implemented in soft-landing experiments are simulated. It is found that under a high-speed condition, the gold cluster Au₁₀ can undergo a sequence of structural transitions after colliding with a defect-free TiO₂ (110) surface. When the TiO₂ (110) surface possesses oxygen vacancies, however, chemical bonds …

Icosahedral B12-Containing Core–Shell Structures Of B80, Hui Li, Nan Shao, Bo Shang, Lan-Feng Yuan, Jinlong Yang, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

Low-lying icosahedral (I_h) B₁₂-containing structures of B₈₀ are explored, and a number of core–shell isomers are found to have lower energy than the previous predicted B₈₀ fullerene. The structural transformation of boron clusters from tubular structure to core–shell structure may occur at a critical size less than B₈₀.

Graphene-Like Bilayer Hexagonal Silicon Polymorph, Jaeil Bai, Hideki Tanaka, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

We present molecular dynamics simulation evidence for a freezing transition from liquid silicon to quasi-twodimensional (quasi-2D) bilayer silicon in a slit nanopore. This new quasi-2D polymorph of silicon exhibits a bilayer hexagonal structure in which the covalent coordination number of every silicon atom is four. Quantum molecular dynamics simulations show that the stand-alone bilayer silicon (without the confinement) is still stable at 400 K. Electronic band-structure calculations suggest that the bilayer hexagonal silicon is a quasi-2D semimetal, similar to a graphene monolayer, but with an indirect zero band gap.

Silver Nanoparticle Polymer Composite Based Humidity Sensor, Aoife Power, Tony Betts, John Cassidy

Articles

Silver nanoparticles were synthesised by a chemical reduction process in order to produce an aqueous colloidal dispersion. The resulting colloids were then characterised by a combination of UV-Vis spectroscopy, dynamic light scattering, X-ray diffraction and transmission electron microscopy and the nanoparticles were found to have an average diameter of 20–22 nm. The Ag/polymer nanocomposites were then applied to platinum interdigital electrodes as sensor coatings and the capability of the resulting sensor as a humidity detector investigated. With the application of 1 V, a current developed which was found to be directly proportional to humidity levels. The sensor gives a reversible, …

Transition States In Ei Reactions, Charles A. Kingsbury

Chemistry Department: Faculty Publications

The pyrolysis of amine oxides, sulfoxides, selenoxides, and esters to form alkenes is believed to be a concerted reaction with a cyclic transition state. Phosphine oxides, sulfones, and nitro compounds are unreactive. This study seeks to identify reasons for the lack of reactivity of the latter. Transition states were located for all substrates progressing from RHF/3-21G* to the MP2/6-31+G(d,p) level (in certain cases). For sulfones and nitro compounds, two possible reasons for lack of reactivity were considered: (1) Atoms approaching one another in the transition state may be considered to participate in a local n_O→σ*_{CH …}

Toxicodynamics And Biotransformation Of Azaspiracids Incorporating Liquid Chromatography-Tandem-Mass Spectrometry (Lc-Ms/Ms) Techniques., Daniel O'Driscoll

Theses

Azaspiracids (AZAs) are a family of lipophilic polyether marine biotoxins, that have caused a number of human intoxication incidents in Europe since 1995, which was the first incident reported following the consumption by consumers of intoxicated shellfish {Mytilus edulis). This class of phycotoxins has been responsible for extended closures of shellfisheries in various locations around Europe, where levels of AZAl-3 are regulated in shellfish. Since their discovery in 1995, AZAs have become the focus of extensive research, resulting in the discovery of numerous analogues. Only AZAl and AZA2 have been found in phytoplankton and all the other analogues are believed …

Application Of Liquid Chromatography - Tandem Mass Spectrometry For The Determination Of Veterinary Drug Residues In Food Of Animal Origin, Brian Kinsella

Theses

The QuEChERS (quick, easy, cheap, effective, rugged and safe) sample preparation approach was evaluated for the extraction of anthelmintic residues from bovine milk and tissues. Liquid chromatography coupled to tandem mass spectrom.etry (LC- MS/MS) was used for detection and quantification of residues, which included the benzimidazoles (BZs), macrocyclic lactones (MLS) and the generally overlooked flukicides.

Initial work focused on the optimisation of a QuEChERS method to effectively extract anthelmintic residues from milk and liver. The method involves the extraction of residues with acetonitrile (MeCN) in the presence of salts (MgS04 and NaCl) to induce phase separation. After shaking and centrifugation, …

Bioavailability Of Biosolids- And Consumer Product-Associated Polybrominated Diphenyl Ether (Pbde) Flame Retardants To Terrestrial Invertebrates, Michael O. Gaylor

Dissertations, Theses, and Masters Projects

The primary objectives of this research were therefore to evaluate polybrominated diphenyl ether (PBDE) bioavailability to ecologically distinct soil invertebrates exposed to Penta-BDE-treated consumer polyurethane foam (PUF) products and biosolid products with incurred PBDEs. In laboratory bioassays, earthworms (Eisenia fetida) bioaccumulated SigmaPBDEs (47+99+100+183) up to 11,000 mug/kg lipid after 28 days from a mixture of artificial soil and anaerobically-digested sludge biosolid (ADB). Earthworms also bioaccumulated SigmaPBDEs (47+99+100+153+154+183) up to 13,500 and 838,000 mug/kg lipid after 28 d from a mixture of artificial soil and composted sludge biosolid (CB) and Penta-BDE-spiked artificial soil (SAS), respectively. No previous lab studies on bioaccumulation …

Arsenic Speciation Analysis Of Biological Fluids : A Study Of Liquid Chromatography Coupled To Analytical Atomic Spectrometric Instrumentation, Kanna Ito

Legacy Theses & Dissertations (2009 - 2024)

Arsenic exists as many different chemical forms including inorganic, methylated and dietary species. The toxicity of these species varies: some are highly toxic and can cause adverse health effects in many parts of the body; others are considered relatively non-toxic. Monitoring arsenic exposure is usually accomplished by its direct measurement in biological fluids. Urine is the specimen of choice for assessing arsenic exposure, because of its short biological half-life in blood. There have been very few studies of arsenic species in blood, yet such research can provide valuable information on arsenic distribution and its metabolism in the body.

Elucidating The Structure Of Protein Aggregates By Raman Spectroscopy, Ludmila A. Popova

Legacy Theses & Dissertations (2009 - 2024)

The structures and properties of amyloid fibrils are of considerable interest due to their associations with numerous neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease and transmissible spongiform encephalopaties (prion diseases). Understanding fibrillogenesis at a molecular level requires detailed structural characterization of amyloid fibrils. However amyloid fibrils are difficult objects to study due to their non-crystalline and insoluble nature. These properties make the application of classical tools of structural biology, such as X-Ray crystallography and solution Nuclear Magnetic Resonance spectroscopy, impractical for structural characterization of protein fibrils.

Analytical Chemistry 2.0, David Harvey

Chemistry & Biochemistry Faculty Publications

No abstract provided.

Physical And Biochemical Assessment Of Mexican Palo Verde Response To Chromium Toxicity, Yong Zhao

Open Access Theses & Dissertations

In the United States, about 1/3 of the 1400 superfund sites have been reported to be chromium contaminated, making chromium the second most common metal found in superfund chemical contamination sites. Chromium removal from soil has commonly been carried out via chemical, physical, and thermal processes. However, these methods are expensive and/or invasive to local ecosystems. In contrast to these techniques, phytoremediation (the use of plants to remove toxic substances from areas containing contamination at low or medium levels) appears to be a cost-effective and environmentally friendly process for chromium removal. However, most reports on chromium phytoremediation suggest that this …