Chemistry Commons^™

Mechanism Of Lysine 48 Selectivity During Polyubiquitin Chain Formation By The Ube2r1/2 Ubiquitin-Conjugating Enzyme, Spencer Hill, Joseph S. Harrison, Steven M. Lewis, Brian Kuhlman, Gary Kleiger

College of the Pacific Faculty Articles

Lysine selectivity is of critical importance during polyubiquitin chain formation because the identity of the lysine controls the biological outcome. Ubiquitins are covalently linked in polyubiquitin chains through one of seven lysine residues on its surface and the C terminus of adjacent protomers. Lys 48-linked polyubiquitin chains signal for protein degradation; however, the structural basis for Lys 48 selectivity remains largely unknown. The ubiquitin-conjugating enzyme Ube2R1/2 has exquisite specificity for Lys 48, and computational docking of Ube2R1/2 and ubiquitin predicts that Lys 48 is guided to the active site through a key electrostatic interaction between Arg 54 on ubiquitin and …

An Investigation Into The Use Of Polymer Bound Boronic Acid For Glucose Detection In Paper Based Microfluidic Devices, Spencer A. Schultz

Master's Theses

Paper Based Microfluidic Devices (microPADs) are a new platform for point-of-care diagnostic assays for use in resource-limited settings. These devices rely typically on enzymatic assays to produce their results, which makes them susceptible to degradation when exposed to extreme environmental conditions such as high temperature. In order to overcome this limitation, this research project focused on investigating the use of polymers instead of enzymes to detect analytes on microPADs.

Polymer-bound boronic acid, a glucose and pH sensitive polymer, was incorporated into microPADs in order to develop a chronometric, paper-based glucose assay. The polymer was tested with both lateral and vertical …

Understanding College Students’ Exam Process In A General Chemistry Course, Angela Willson

Masters Theses

The main way most college chemistry courses assess what a student has learned is through a summative exam. After introductory science courses, such as general chemistry, many students cite poor teaching and disappointing grades in these courses as a reason for dropping out of STEM programs. There has been a lack of qualitative research on students’ experiences of the complete process of taking an exam from start to finish, or the exam process, which includes preparing for an exam, taking an exam, receiving feedback, and responding to feedback after the exam has been graded.

My goal in this exploratory study …

Metals Additive Manufacturing Powder Aging Characterization, Thomas Russell Lovejoy, Nicholas Karl Muetterties, David Takeo Otsu

Mechanical Engineering

The metallic additive manufacturing process known as selective laser melting requires highly spherical, normally distributed powder with diameters in the range of 10 to 50 microns. Previous observations have shown a degradation in powder quality over time, resulting in unwanted characteristics in the final printed parts. 21-6-9 stainless steel powder was used to fabricate test parts, with leftover powder recycled back into the machine. Powder samples and test specimens were characterized to observe changes across build cycles. Few changes were observed in the physical and mechanical properties of the specimens, however, there were indications of chemical changes across cycles. Potential …

Harmful And Beneficial Role Of Ros, Sergio Di Meo, Tanea Reed, Paola Venditti, Victor M. Victor

EKU Faculty and Staff Scholarship

Reactive oxygen species (ROS) are an unavoidable byproduct of oxygen metabolism and their cellular concentrations are determined by the balance between their rates of production and their rates of clearance by various antioxidant compounds and enzymes. For a long time ROS were thought to cause exclusively toxic effects which were associated with various pathologies, including carcinogenesis, neurodegeneration, atherosclerosis, diabetes, and aging. However, to date, it is known that while prolonged exposure to high ROS concentrations may lead to various disorders, low ROS concentrations exert beneficial effects regulating cell signaling cascades.

Screening The Low Molecular Weight Fraction Of Human Serum Using Atr-Ir Spectroscopy, Franck Bonnier, Matthew J. Baker, Hugh Byrne

Articles

Vibrational spectroscopic techniques can detect small variations in molecular content, linked with disease, showing promise for screening and early diagnosis. Biological fluids, particularly blood serum, are potentially valuable for diagnosis purposes. The so-called Low Molecular Weight Fraction (LMWF) contains the associated peptidome and metabolome and has been identified as potentially the most relevant molecular population for disease-associated biomarker research. Although vibrational spectroscopy can deliver a specific chemical fingerprint of the samples, the High Molecular Weight Fraction (HMWF), composed of the most abundant serum proteins, strongly dominates the response and ultimately makes the detection of minor spectral variations a challenging task. …

Glutamic Acid Resorcinarene-Based Molecules And Their Application In Developing New Stationary Phases In Ion Chromatography, Tayyebeh Panahi

Theses and Dissertations

Resorcinarenes can be functionalized at their upper and lower rims. In this work, the upper rim of a resorcinarene was functionalized with glutamic acids and the lower rim was functionalized with either methyl or undecyl alkyl groups. The cavitands were characterized by nuclear magnetic resonance (NMR), mass spectrometry (MS), UV-vis spectroscopy, dynamic light scattering (DLS) and electron microscopy. The binding of resorcinarene with amine guests was studied in DMSO by UV-vis titration. The obtained binding constants (K values) were in the range of 12,000-136000 M-1. The resorcinarenes were shown to form aggregates in a variety of solvents. The aggregates were …

Supramolecular Assembly Of Metal-Organic Tubes Constructed From The Ditopic Heteroscorpionate Ligand (4-Nh2C6H4)Chpz2 (Pz = Pyrazol-1-Yl) And Silver(I), James R. Gardinier, Jeewantha S. Hewage, Justin Hoffman, Sergey V. Lindeman, Natalia B. Shustova

Chemistry Faculty Research and Publications

The possibility of constructing tubular metal-organic structures with aid of weak hydrogen-bonding interactions between suitably designed metallacycles was explored. For this purpose, the new heteroditopic ligand (4-NH₂C₆H₄)CHpz₂ (L1) was prepared in good (75 %) yield by a one-pot procedure starting from commercial 4-acetamidobenzaldehyde. The equimolar reactions between L1 and various silver(I) salts gave the intended 1:1 complexes in which the metallacycles were assembled into tubes. However, the exact nature of the assemblies (including their solvate compositions) varied depending on anion, solvent, and concentration of the original crystallization solution. For the trifluoromethanesulfonate anion, a …

Mononuclear Iron-(Hydro/Semi)Quinonate Complexes Featuring Neutral And Charged Scorpionates: Synthetic Models Of Intermediates In The Hydroquinone Dioxygenase Mechanism, Amanda E. Baum, Sergey V. Lindeman, Adam T. Fiedler

Chemistry Faculty Research and Publications

Neutral and anionic scorpionate ligands have been employed to generate active-site models of hydroquinone dioxygenases (HQDOs). While the nonheme Fe center in nearly all HQDOs is coordinated to one Asp (or Glu) and two His residues, 1,2-gentisate dioxygenase (GDO) is unique in featuring a three His triad instead. A synthetic GDO model was therefore prepared with the neutral tris(4,5-diphenyl-1-methylimidazol-2-yl)phosphine (^Ph2TIP) ligand. The gentisate substrate was mimicked with the bidentate ligand 2-(1-methylbenzimidazol-2-yl)hydroquinonate (BIHQ). X-ray diffraction analysis of the resulting complex, [Fe(^Ph2TIP)(BIHQ)]OTf (1a), revealed a distorted square-pyramidal geometry. Structural and electrochemical data collected for 1a were compared to …

Development And Characterization Of Reagent Pencils For Microfluidic Paper Based Analytical Devices, Cheyenne H. Liu

Master's Theses

Microfluidic paper based analytical devices (microPADs) are a novel platform for point of care (POC) diagnostics. Limitations of reagent shelf life have been overcome with the introduction of reagent pencils as a method for solid-based reagent deposition. While useful, little work has been reported on the characterization and optimization of reagent pencils. Herein, an investigation on reagent pencil composition and efficiency is conducted via colorimetric release profile tests utilizing an erioglaucine disodium salt that yields a quantifiable blue colored product in the presence of water. Within this work, an investigation on the molecular weight dependence, polymer chain end functionality, and …

Thermochemical Properties Of Fluorinated Hydrocarbons, Hydroperoxides, And Fluorinated Hydroperoxides; Thermochemistry And Kinetics On Dissociation And Association Reactions Of Oxiranyl Radical, Heng Wang

Dissertations

Thermochemical properties on fluorinated hydrocarbons, alcohol, hydroperoxides, and alkyl hydroperoxides are determined. Reaction kinetics and modeling on the three member ring cyclic ether radical, oxiranyl radical, are studied under atmospheric and combustion environments.

Molecular geometries, vibration frequencies, internal rotor potentials, and thermo-chemical properties (ΔfHº298, S°(T) and C°p(T)) for fluorinated-hydrocarbons, thermochemical properties and bond energies, for alkyl and fluoro hydroperoxides and fluoro alcohols are determined with comparison of data from a number of different ab initio, density functional theory (DFT) and composite calculation methods, and basis sets.

Kinetic parameters for unimolecular decomposition and isomerization reactions of the oxiranyl radical are determined …

Studies On Purification And Functionalization Of Carbon Nanotubes And Their Aqueous Phase Behavior, Zheqiong Wu

Dissertations

Carbon nanotubes (CNTs) are known to have unique mechanical, thermal and electrical properties which make them attractive for a wide range of applications ranging from batteries to sensors. CNTs are rolled up graphene sheets where the single-walled CNTs (SWCNTs) and multi-walled CNTs (MWCNTs) are classified according to the number of concentric rings. In this dissertation, the focus is on several different aspects of MWCNTs. These include purification, functionalization and colloidal behavior.

MWCNTs are insoluble in solvents and therefore some degree of functionalization is required prior to their real-world applications. Oxidation debris is generated during carboxylation which is usually the first …

Segmentation And Additive Approach: A Reliable Technique To Study Noncovalent Interactions Of Large Molecules At The Surface Of Single‐Wall Carbon Nanotubes, Ana M. Torres, Steve Scheiner, Ajit K. Roy, Andrés M. Garay-Tapia, John J. Bustamante, Tapas Kar

Chemistry and Biochemistry Faculty Publications

This investigation explores a new protocol, named Segmentation and Additive approach (SAA), to study exohedral noncovalent functionalization of single-walled carbon nanotubes (SWNTs) with large molecules, such as polymers, bio-molecules etc, by segmenting the entire system into smaller units to reduce computational cost. A key criterion of the segmentation process is the preservation of the molecular structure responsible for stabilization of the entire system in smaller segments. Noncovalent interaction of linoleic acid (LA, C18H32O2), a fatty acid, at the surface of a (10,0) zigzag nanotubeis considered for test purposes. Three smaller segmented models have been created from the full (10,0)-LA system …

A Tonb-Dependent Receptor Regulates Antifungal Hsaf Biosynthesis In Lysobacter, Ruping Wang, Huiyong Xu, Liangcheng Du, Shan-Ho Chou, Hongxia Liu, Youzhou Liu, Fengquan Liu, Guoliang Qian

Liangcheng Du Publications

Lysobacter species are Gram-negative bacteria that are emerging as new sources of antibiotics, including HSAF (Heat Stable Antifungal Factor), which was identified from L. enzymogenes with a new mode of action. LesR, a LuxR solo, was recently shown to regulate the HSAF biosynthesis via an unidentified mechanism in L. enzymogenes OH11. Here, we used a comparative proteomic approach to identify the LesR targets and found that LesR influenced the expression of 33 proteins belonging to 10 functional groups, with 9 proteins belonging to the TBDR (TonB-Dependent Receptor) family. The fundamental role of bacterial TBDR in nutrient uptake motivates us to …

Oleanolic Acid Inhibits High Salt-Induced Exaggeration Of Warburg-Like Metabolism In Breast Cancer Cells, Suneetha Amara, Mu Zheng, Venkataswarup Tiriveedhi

Chemistry Faculty Research

Cancer cells have a proliferative advantage by utilizing intermediates of aerobic glycolysis (Warburg effect) for their macromolecule synthesis. Although the exact causes of this Warburg effect are unclear, high osmotic stress in solid tumor microenvironment is considered one of the important factors. Oleanolic acid (OA) is known to exert anti-inflammatory and anti-cancer effect. In our current studies, using breast cancer cell lines, we determined the protective role of OA in high salt-mediated osmotic stress-induced cancer growth. Hypertonic (0.16 M NaCl) culture conditions enhanced the cancer cell growth (26 %, p < 0.05) and aerobic glycolysis as marked by increased glucose consumption (34 %, p < 0.05) and lactate production (25 %, p < 0.05) over untreated cells. This effect was associated with increased expression and activity of key rate-limiting enzymes of aerobic glycolysis, namely hexokinase, pyruvate kinase type M2, and lactate dehydrogenase A. Interestingly, this high salt-mediated enhanced expression of aerobic glycolytic enzymes was efficiently reversed by OA along with the decreased cancer cell proliferation. In cancer cells, enhanced aerobic glycolysis is associated with the decreased mitochondrial activity and mitochondrial-associated caspase activity. As expected, high salt further inhibited the mitochondrial related cytochrome oxidase and caspase-3 activity. However, OA efficiently reversed the high salt-mediated inhibition of cytochrome oxidase, caspase activity, and pro-apoptotic Bax expression, thus suggesting that OA induced mitochondrial activity and enhanced apoptosis. Taken together, our data indicate that OA efficiently reverses the enhanced Warburg-like metabolism induced by high salt-mediated osmotic stress along with potential application of OA in anti-cancer therapy.

Rotational And Hyperfine Analysis Of Aus, Ian A. Wyse

Macalester Journal of Physics and Astronomy

Gas phase diatomic gold sulfide, AuS, was analyzed using optical spectroscopy. High-resolution spectra were collected and characterized and a global fit of the A²∑⁺-X²∏_3/2 (0,0), B²∑^–-X²∏_3/2 (0,0), and C²Δ_3/2-X²∏_1/2 (0,0) transitions at 15570 cm^-1, 16290 cm^-1, and 17670 cm^-1 was compiled and resulted in rotational constant determinations for the A²∑⁺((2σ)¹(4π)⁴), B²∑^–((2σ)²(4π)²(2σ*)¹), and C²Δ_{3/2 …}

The Effects Of Phosphonic Acids In Dye-Sensitized Solar Cells, Keith Edward James

Dissertations and Theses

Novel methods for the construction of dye-sensitized solar cells (DSSCs) were developed. A thin dense underlayer of TiO₂ was applied on fluorine-doped tin oxide (FTO) glass using as a precursor Tyzor AA-105. Subsequently a mesoporous film of P-25 TiO₂ was applied by spreading a suspension uniformly over the surface of the underlayer and allowing the plate to slowly dry while resting on a level surface. After sintering at 500° C slides were treated with TCPP as a sensitizing dye and assembled into DSSCs. A novel method was used to seal the cells; strips of Parafilm® were used as …

Glen Helen Water Quality: A 5-Year Exploration, 2011-2015 (Acs), Audrey E. Mcgowin Ph.D.

Chemistry Faculty Publications

No abstract provided.

Enhanced Adhesion Of Superhydrophobic Zno Surface, Liqiu Zheng Dr., Chan Kwaichow B.

Georgia Journal of Science

The superhydrophobicity and the strong solid-liquid adhesion of the dually structured ZnO surface are attributed to the suitable size of microstructure and nanostructure. This phenomenon, so different from the Lotus effect, can be called the Petal effect— the super hydrophobicity and the enhanced solid-liquid adhesion coexist on the same surface. The Cassie impregnating model was proposed to understand the underlying reason.

The Study Of Drug Interactions During Separation Using Gas Chromatography – Mass Spectrometry, Leanne Mocniak

Capstone Projects/Undergraduate Honors Theses

There are numerous existing techniques for forensic toxicological testing, but each one has limitations. Although there have been significant improvements in these techniques over the past 10 years, it still remains very difficult to successfully identify a wide range of drugs from one sample using a single method [12]. This difficulty arises from the major differences in molecular structure, volatility and stability in solution between these drugs. The overall goal of this study is to develop a method using gas chromatography (GC) coupled with triple quadrupole mass spectrometry (GC/MS/MS) to separate and accurately identify 10 different drugs of abuse from …

Multi-Regression Prediction Of Metal Partition Coefficients Under Various Physical/Chemical Conditions Design Of Experiments As, Cr, Cu, Ni And Zn, Eid A. Alkhatib, Danielle Grunzke, Trey Chabot

Chemistry & Physics Faculty Publications

The behavior of metals in surface water is complex and their partition coefficients can be impacted by many factors. Organic matter (OM) content in sediments, pH and salinity, are factors that may influence speciation and partitioning of metals. The difficulty in describing the impacts and relationships are that these processes are interconnected with no dominant associations among all. In this study, the partitioning of five metals (As, Cr, Cu, Ni and Zn) under different levels of salinity, pH, and OM content were investigated. A series of factorial design experiments are evaluated in which three levels of OM are tested each …

Dendrimer Modified Silica Nanoparticles As Fluorescent Chemosensors For The Detection Of Copper And Cyanide Ions, Alicia Luhrs

Master's Theses

A series of silica nanoparticle-based fluorescent chemosensors were synthesized for the sensitive and selective detection of Cu²⁺ ions in aqueous solution and subsequent CN^- ion detection. Silica nanoparticles (SNP) were modified with branching polyamidoamine (PAMAM) dendrimers, which function as selective turn-off Cu²⁺ ion chelators and platforms for the attachment of rhodamine isothiocyanate (RITC) or fluorescein isothiocyanate (FITC) fluorescent dyes. In the presence of Cu²⁺ ions, the emission of the fluorescent dye is quenched by Forster resonance energy transfer (FRET) and is dependent upon dendrimer generation, pH, fluorescent dye, and surface charge. The quenching effectiveness was analyzed …

Measuring Accuracy Of Two 3d Printing Materials, Mudassir Ali

Master of Technology Management Plan II Graduate Projects

Part accuracy is one of the important aspect in the manufacturing industry. The overall inaccuracy of the parts being built by RP technology has been one of the major challenges that need to be overcome. Though all the printing materials come with specifications, but the suppliers and manufactures does not specify the accuracy of the materials. In this study we established a study which compares the accuracy of the materials in consideration and performed an experiment to establish the superiority of a material in terms of accuracy over each other. The purpose of this project was to compare the dimensional …

Light-Activated Photocurrent Degradation And Self-Healing In Perovskite Solar Cells, Wanyi Nie, Jean-Christophe Blancon, Amanda J. Neukirch, Kannatassen Appavoo, Hsinhan Tsai, Manish Chhowalla, Muhammad A. Alam, Matthew Y. Sfeir, Claudine Katan, Jacky Even, Sergei Tretiak, Jared J. Crochet, Gautam Gupta, Aditya D. Mohite

Publications and Research

Solution-processed organometallic perovskite solar cells have emerged as one of the most promising thin-film photovoltaic technology. However, a key challenge is their lack of stability over prolonged solar irradiation. Few studies have investigated the effect of light soaking on hybrid perovskites and have attributed the degradation in the optoelectronic properties to photochemical or field-assisted ion migration. Here we show that the slow photocurrent degradation in thin-film photovoltaic devices is due to the formation of light-activated meta-stable deep-level trap states. However, the devices can self-heal completely by resting them in the dark for <1 min or the degradation can be completely prevented by operating the devices at 0°C. We investigate several physical mechanisms to explain the microscopic origin for the formation of these trap states, among which the creation of small polaronic states involving localized cooperative lattice strain and molecular orientations emerges as a credible microscopic mechanism requiring further detailed studies.

Inhibitory Effects Of Unique Sulfonamides On Leishmania Tarentolae And Potential Pathway Of Inhibition, Jade M. Katinas

Theses and Dissertations

Leishmaniasis is an endemic disease caused by the protozoan parasite Leishmania. Current treatments for the parasite are limited by cost, availability, and drug resistance as the worldwide occurrence of leishmaniasis continues to be more prevalent. Sulfonamides are a class of compounds with medicinal properties that have been used to treat bacterial and parasitic diseases via various pathways. In this study, newly synthesized, unique structural analogs of sulfonamide compounds were assessed for their impact on Leishmania cell viability and potential pathways for inhibition were evaluated. Leishmania tarentolae (ATCC Strain 30143) axenic promastigote cells were grown in BHI medium and treated with …

Gamma Aapeptides As Host Defense Peptide Mimics, Yaqiong Li

USF Tampa Graduate Theses and Dissertations

There has been increasing concern regarding the emergence of multi-drug resistant pathogens. The resistance develops when pathogens, especially bacteria, are frequently exposed to conventional antibiotics, as they are heavily used in both human and livestock. This is due to the high target specificity of conventional antibiotics, which places pathogens in high selective pressures and eventually results in drug resistant by mutations. To address this issue, global actions and cooperation are needed. At the same time, new technologies and strategies need to be developed. Host defense peptides (HDPs) are widely found in the innate immune system. They show both direct antimicrobial …

High-Valent Organometallic Palladium And Nickel Complexes And Their Roles In Carbon-Carbon And Carbon-Heteroatom Bond Formation Reactions, Jason Wesley Schultz

Arts & Sciences Graduate Student Theses and Dissertations

The development of palladium catalysis has been influential in a wide range of organic transformations, in particular C-C coupling, C-Heteroatom coupling and C-H functionalization reactions. These catalytic transformations normally proceed through the Pd0/II catalytic cycle. These reactions are remarkably useful, however, they suffer from two major problems: -hydride elimination and palladium black deposition. To circumvent these problems, recent reports have been focused on developing novel organic transformations proceeding through high-valent palladium and nickel catalytic cycles. To this point, we recently reported the isolation and characterization of various mononuclear PdIII complexes using the tetradentate ligands, N,N-di-alkyl-2,11-diaza[3.3](2,6)pyridinophane (RN4, R = tBu, iPr, …

Cyclotron Production And Biomedical Imaging Applications Of The Pet Isotope Manganese-52, Andrew Lake Wooten

McKelvey School of Engineering Graduate Student Theses & Dissertations

Manganese is an important element for biomedical research because of its roles as an essential micronutrient and as a neurotoxin from chronic elevated exposure, as well as the role of manganese(II) as a paramagnetic core for contrast agents in T1-weighted magnetic resonance imaging (MRI). Using a radiotracer of manganese provides excellent sensitivity for studying these phenomena, but only 52Mn met the criteria for our experiments: (1) a half-life (t1/2=5.6 days) that was long enough to examine timepoints over several days, (2) a half-life that was short enough to emit sufficient counts for a realistic scan time, and (3) emitted radiation …

Environmental Fullerene Chemistry: Elucidating Critical Reaction Pathways And Resulting Products In The Aqueous Phase, Jiewei Wu

McKelvey School of Engineering Graduate Student Theses & Dissertations

As the production of fullerenes and fullerene-based materials approaches industrial scale, there are increasing interests/concerns regarding their (potential) environmental impact(s) upon release. To date, a number of critical, aqueous-based fullerene transformation pathways under environmentally relevant conditions remain poorly understood. Comprehensive, fundamental, and quantitative understanding of the potential (major) reaction pathways and resulting products of fullerene materials, particularly in aquatic systems, is now crucial for their accurate fate, transport, life cycle, risk assessment(s), and thus ultimate material sustainability.

Herein, this dissertation is focused on identifying and elucidating aqueous transformation pathways of fullerene materials, focused on C60 as a model fullerene, under …

Epoxy Siloxane Self-Cleaning Coating Using F64pczn/Tio2 Photocatalyst Composite, James F. Sullivan

Seton Hall University Dissertations and Theses (ETDs)

A new photocatalytic composite powder incorporated into a siloxane epoxy polymer has been shown to yield a highly efficient self-cleaning coating. The composite, which makes greater use of light in the visible/near-infrared (NIR) region, was prepared by coating a nano-particle photocatalytic TiO₂ with 3% w/w of F₆₄PcZn photosensitizer resulting in a dark green powder. The F₆₄PcZn/P25 TiO₂ composite exhibited a greater photo-induced degradation of methyl red, a model surface contaminant, compared to traditional nano-particle photocatalytic TiO₂. Singlet oxygen (¹Δ_g ¹O₂), generated form the F₆₄PcZn, …