Chemistry Commons^™

Design And Characterization Of Composite Membranes For Solar Fuel Generating Devices, Ibtehaj Fahad Alshdoukhi

Theses and Dissertations

Currently, there is a great need for research and development on new sources of energy in order to meet energy demands in a clean, efficient, sustainable, economical and environmentally friendly way. A system that promises to meet these requirements is water splitting through artificial photosynthesis, generating hydrogen and oxygen, effectively storing light energy in the form of fuel such as H2. One main limitation in artificial photosynthesis is that the membrane must be able to conduct the ions involved in redox reactions, as well as the electrons/hole carriers produced by light absorption, while being mechanically stable and optically transparent. No …

Thermosetting Polymers Via Azide Alkyne Cycloaddition, Richard H. Cooke Iii

Dissertations

This dissertation exploits properties inherent to azide-alkyne cycloaddition and applies practical solutions to difficult problems. Chapter II addresses structure-property relationships in glassy azido-alkyne matrices by varying the identity of the central linkage within tetrapropargyl bis-aniline-type crosslinkers, and by the addition or omission of Cu(I) catalyst. This systematic study showed that an ether or methylene linkage yielded lower melting tetrapropargyl crosslinkers that were soluble in, and produced homogeneous, networks when cured with, a standard azido resin, di(3-azido-2-hydroxypropyl) ether of bisphenol-A; in contrast, a sulfone linkage yielded a relatively insoluble crosslinker and poorly dispersed, heterogeneous networks when reacted with the same …

Triacetin Enhances Levels Of Acrolein, Formaldehyde Hemiacetals, And Acetaldehyde In Electronic Cigarette Aerosols, Shawna Vreeke, David H. Peyton, Robert Strongin

Chemistry Faculty Publications and Presentations

The health effects of inhaled electronic cigarette (ecigarette) flavoring compounds are largely unknown. Earlier reports of their chemical reactivity have been conflicting, with some claiming, for example, that the degradation of flavoring chemicals in e-cigarettes to aldehydes is statistically insignificant. It is thus important to understand how these molecules react to afford enhanced aerosol products. The purpose of the current study was to investigate the origin of formaldehyde, acrolein, and acetaldehyde in e-cigarettes that contain the popular additive, triacetin (TA). By using 13C labeling and a combination of 1H NMR and 13C NMR, we were able to identify that ester …

Thermodynamic And Kinetic Study Of The Removal Of Cu2+ And Pb2+ Ions From Aqueous Solution Using Fe7s8 Nanomaterial, Jesus Cantu, Diego F. Gonzalez, Yvette Cantu, Thomas Eubanks, Jason Parsons

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

In the present study, pyrrhotite (Fe7S8) was investigated for the removal of Pb2+ and Cu2+ ions from aqueous solution. The Fe7S8 material was prepared through a solvothermal method and was characterized using XRD. The average particle size for the nanomaterial was determined to be 29.86 ± 0.87 nm using XRD analysis and Scherrer's equation. Batch studies were performed to investigate the effects of pH, time, temperature, interfering ions, and the binding capacity of Pb2+ and Cu2+ ions to the Fe7S8 nanomaterial. During the pH profile studies, the optimum pH for the binding of Pb2+ and Cu2+ was determined to be …

The Photodynamic And Structural Analyses Of Advanced Materials For Solar Fuel Conversion, Brian Pattengale

Dissertations (1934 -)

Mitigating the current and future climate and pollution issues that have been brought on by the combustion of fossil fuels is of utmost importance and will rely on, in part, the availability of renewable fuel sources. Of the possible sources of energy, solar is abundant, but must be harnessed efficiently and stored as a solar fuel to overcome the current storage issues that limit photovoltaic cells. One such fuel, H2(g), represents a carbon-neutral source of energy if it can be efficiently liberated from water via the water splitting reaction. Thus, much attention is focused on designing materials to perform the …

Design, Synthesis And Study Of Redox And Optoelectronic Properties Of Aromatic Oxidants And Polycyclic Aromatic Hydrocarbons, Mohammad Mosharraf Hossain

Dissertations (1934 -)

Organic materials play a significant role for the next generation photovoltaic devices that convert solar energy into usable forms of energy. In this regard, polycyclic aromatic hydrocarbons (PAHs) are fundamental tools in the developing area of molecular electronics and photovoltaics as they show excellent optical/electronic properties and are well-suited for applications in such developing areas as flexible display devices, field effect transistors and solar cell panels. Design and synthesis of novel materials for photovoltaics applications would require the proper understanding the mechanism of charge transport and identification of the structural features necessary in a particular molecular wire or PAH. To …

Characterizing The Activity Of Antimicrobial Peptides Against The Pathogenic Bacterium Clostridium Difficile In An Anaerobic Environment, Adenrele Mojeed Oludiran

Chemistry & Biochemistry Theses & Dissertations

Clostridium difficile is an anaerobic Gram-positive pathogen with high treatment costs and mortality and very high antibiotic tolerance. Antimicrobial host-defense peptides (HDPs) produced naturally by animal immune systems are promising candidates to develop novel therapies for bacterial infection because they cause oxidative stress that damages multiple targets in bacterial cells, so it is difficult for bacteria to evolve resistance to these attacks.

Piscidins, fish-derived HDPs that can also form complexes with copper (Cu) to enhance their activities, are very active against multiple bacterial species in an aerobic environment. We examined their activity against C. difficile and other species in an …

The Effect Of Soxhlet Extraction And Synthesis Temperature On Properties Of Polyaniline, Samuel Watson Stahl

Chemistry & Biochemistry Theses & Dissertations

Polyaniline was synthesized by the chemical oxidation of aniline in an HCl solution by ammonium persulfate. The temperature of the synthesis was varied to increase the molecular weight of the polymer from 37,600 Da to 52,400 Da. Soxhlet extraction using methanol as the primary solvent was performed on half the sample in order to further increase the average molecular weight by approximately 3150 Da and decrease the polydispersity index by 0.8. Films were cast from 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone (DMPU) and N-methyl-2-pyrrolidone (NMP) and then doped with trifluoromethanesulfonic acid.

The effect of the soxhlet extraction and synthesis temperature on the polymer’s properties …

Advances In Amino Acid Analysis For Marine Related Matrices And Its Application To Coastal Shelf Settings In The Canadian Arctic, Rachel M. Mcmahon

OES Theses and Dissertations

Amino acids comprise up to 50% of organic matter in cellular material and are a major fraction of oceanic organic carbon. Amino acids are also considered highly labile during organic matter recycling, making them useful proxies for organic carbon cycling. Nevertheless, analysis of individual amino acids has been burdened by lengthy derivatization and complex analysis since the 1950s. In this thesis, I describe the modification of advanced analytical techniques, developed in the biomedical field, for analysis of marine matrices which allow the determination of at least 40 amino acids without the need for lengthy sample preparation and derivatization, twice the …

Study Of The Visual Adaptation Mechanism In Marine Species With The Change Of Habitation Depth., Demid Osipov, Daniil Moshnikov

The International Student Science Fair 2018

The goal of our work was to determine the principal mechanisms that provide the difference in visual perception of two marine species that live on different depths: T. Pacificus and O. Vulgaris. In nature, visual perception of species that live deeper is shifted towards the blue region. This is related to the fact that red, orange and yellow light is absorbed more strongly by water than the blue light. On the other hand, the visual perception spectrum of an animal is determined by the absorption spectrum of the "light sensor" located in rods and cones of its eye retina. These …

Rearrangements Of Fluorinated Cyclopropylamines As A Novel Approach Toward Fluoroalkene-Based Peptidomimetics, Igor Mezentsev, Vera Zaborova

The International Student Science Fair 2018

"Organofluorine molecules have been widely applied in various research fields because of the unique properties of fluorine atoms. One type of fluorinated compounds is fluoroalkene-based peptidomimetics which are structurally similar to amide-containing compounds. They have been prepared to improve the pharmaceutical properties such as bioactivity, target specificity, and metabolic stability of the bioactive amides.

We suggested a new way of synthesizing fluoroalkene-based peptidomimetics through 2-fluoro-2-halocyclopropylamines, which provides an effective way toward fluoroalkene-based peptidomimetics with increased functional group tolerance and possibility of convergent synthesis."

The Effect Of Semiconductor Materials On Solar Cell Efficiency, Shivam Vohra

The International Student Science Fair 2018

The purpose of this project was to increase the efficiency of solar cells through the use of quantum dots and nanoparticles. These substances would increase the efficiency of the semiconductor. The research hypothesis stated that if lead iodide was applied to the semiconductor, then the average voltage, amperage, power, and efficiency of the solar cells would increase. The procedure for this project involved creating a lead iodide and titanium dioxide mixture with dimethylformamide, ethanol, acetylacetone, and Triton X-100 in an autoclave. Then, two milliliters of each solution were applied to cadmium selenide quantum dots to make four different solutions. Each …

Feco2o4 As An Anode Material For Lithium Ion Batteries, Chelsea Wong

The International Student Science Fair 2018

Lithium ion batteries (LIBs) are commonly found in many portable electronic appliances due to their ability to be rechargeable. Currently, commercial anodes in Li-ion batteries (graphite) have a theoretical capacity of around 372 mAh/g, while FeCo2O4 that will be investigated as the anode material has a theoretical capacity of 901.985mAh/g, more than double of the current commercial anode’s capacity. Earlier work done by Sharma et al also showed that FeCo2O4 has a very promising initial capacity of 827mAh/g. As such, the engineering goal is to produce a battery that will have a higher capacity than the current commercial Li-ion batteries …

Conversion Of Photostable Zn-Ma Crystals To Photoreactive, Yu Jing Siong

The International Student Science Fair 2018

Skin cancer is an issue that is increasingly plaguing the world. At least 100,000 new cases of skin cancer are diagnosed each year, and the disease kills over 2,500 people each year in the United Kingdom(UK). 86% died of melanoma, a particular type of skin cancer, cases in the UK are preventable. In addition, around 99% of non-melanoma skin cancers and 95% of melanoma is caused by overexposure to UV radiation. We feel that the key to reducing the number of skin cancer cases would be to raise the awareness of people’s exposure to UV rays. A feasible way to …

Reduction Of Nitro-Compounds By Iron Pentacarbonyl - New Approach To Drug Precursors, Alexander Sharipov, Maria Vladimirovna Galkina

The International Student Science Fair 2018

Reduction of nitro compounds lies at the center of most of the major areas of modern chemical industry, such as pharmacy and dye manufacturing. The precursors in these industrial processes predominantly possess multiple functional groups, including those highly susceptible to reduction by most of the currently used reducing agents. Therefore, the non-selective methods of reduction of precursors result in the loss of such functional groups. Furthermore, common reducing agents can potentially trigger the undesired intramolecular interactions between the substrate molecules and in turn make it impossible to obtain the end product. The rising demand for a cheap and efficient approach …

An Entirely New Molecular Glue For Mof Using Unusual Structural Transformation Of A Coordination Polymer, Sukwoo Jung, Hangyeol Kim, Junseok Ahn

The International Student Science Fair 2018

In this research, an entirely new molecular glue is reported. This ‘coordination polymer glue’ is synthesized from zinc metal and BDC-NPE(2,5-bis{4-[1-(4-nitrophenyl)ethylamino]butoxy}terephthalic acid). Molecular glue transforms from 1D coordination polymer to a 3D cross-linked framework, resulting in a phase change of solution to solid. The carboxylate group of this glue makes the preformed MOF bind to its framework. Therefore, when the solution of molecular glue is mixed with preformed MOF powder and heated, homogeneous and thin MOF film – MOF/ZnNPE film – is fabricated. The film is irrelevant to the kind of its substrate, and its thermal stability was enhanced in …

Utilization Of Papaya’S Sap (Carica Papaya L.) And Water Lettuce (Pistia Stratiotes) To Reduce Protein Amount On Liquid Tofu Waste, Muhammad Dzulfikar Farkhan, Naila Aliyahandra Anzani, Nabila Fikria Santoso

The International Student Science Fair 2018

Liquid waste from tofu production is one of the causes of environmental pollution. This condition happens because liquid tofu waste contain protein. Protein is metabolized by bacteria formed ammonia which emits foul odor. On this research, the protein amount in liquid tofu waste is reduced by the application of papaya’s sap and water lettuce. This research is divided into several steps. First, collecting the liquid tofu waste. second, tapping the papaya’s sap. Third, poured the papaya’s sap into the tofu waste. the next step is keep the mixture between tofu waste and papaya’s sap rest for 6, 18, and 24 …

Recommended Corrective Security Measures To Address The Weaknesses Identified Within The Shapash Nuclear Research Institute, Khadija Moussaid, Oum Keltoum Hakam

International Journal of Nuclear Security

The Shapash Nuclear Research Institute (SNRI) data book was issued by the International Atomic Energy Agency (IAEA) in 2013. The hypothetical facility data book describes the hypothetical site, which is divided into two areas: the low-security area, known as the administrative area, and the very high-security area, known as the protected area. The book contains detailed descriptions of each area’s safety and security measures, along with figures of multiple buildings in both areas, and also includes information about the site’s computer networks.

This paper aims to identify security weaknesses related to the institute’s location, the Administrative Area (AA), the Protected …

Attempted Resolution And Racemization Of Beckmann‐Derived Ctv‐Lactam And The Use Of Chirabite‐Ar® To Determine The Optical Purity Of The Supramolecular Scaffold, Marlon R. Lutz Jr., Elizabeth Ernst, Matthias Zeller, Jacob Dudzinski, Peter Thoresen, Daniel P. Becker

Chemistry: Faculty Publications and Other Works

Chirabite‐AR was employed to differentiate enantiomers of the axially chiral cyclotriveratrylene (CTV)‐derived macrocyclic lactam with baseline separation of most of the proton NMR resonances enabling enantiomeric purity determination of this supramolecular scaffold. Attachment of menthyloxy acetic acid as a chiral auxiliary to the CTV‐Beckmann derived lactam afforded diastereomers that were enriched to a ratio of 87:13, as confirmed by both ¹H NMR and single‐crystal X‐ray diffraction. Basic hydrolysis of the enriched diastereomeric mixture proceeded with rapid bowl inversion to yield racemic CTV‐lactam as confirmed by Chirabite‐AR NMR analysis. Density functional theory (DFT) calculations (M06 2X/6‐31G*) were performed on the …

Recent Progress For Fe-N-C Electrocatalysts In Alkaline Fuel Cells, Xin Deng, Heng-Quan Chen, Ye Hu, Qing-Gang He

Journal of Electrochemistry

Fuel cells are highly recommended nowadays due to their intrinsic advantages such as high energy conversion efficiency, nearly no pollution, and convenient operation. With the development of anion exchange membrane, alkaline fuel cells have gone through a renaissance thanks to their superiorities such as faster reaction kinetics, wider choices for both fuels and electrocatalysts. It is essential to find an appropriate electrocatalyst for oxygen reduction reaction (ORR) to improve the performance of alkaline fuel cells. Further commercialization of the widely used Pt-based materials has suffered from disadvantages such as scarcity and high cost. As alternatives to largely investigated Pt-based materials, …

A Study Of Pulse Electrodeposition On Suppressing The Formation Of Lithium Dendrite, Wen-Jun Guo, Zi-Qiong Li, Ruo-Hao Ke, Dong-Fang Niu, Heng Xu, Xin-Sheng Zhang

Journal of Electrochemistry

A pulse charge method was used to suppress the formation of lithium dendrite on the copper electrode in 0.5 mol·L^-1 LiBr/propylene carbonate (PC) electrolyte. The surface variation of lithium deposition was investigated by scanning electron microscope and impedance measurement. The SEM test showed that the lithium dendrites were formed on the copper electrode during the traditional process of electrodeposition. However, the formed dendrite was suppressed by pulse charge method. The results of the impedance measurement confirmed that the pulse electrodeposition could suppress the dendrite under the optimized duty ratio (0.5). The long single pulse deposition time decreased the resistance …

Pt/G-C3N4 Nanosheet For Visible Light-Induced Enhancement Of The Activity For Formic Acid Electro-Oxidation, Yong-Rong Sun, Chun-Yu Du, Guo-Kang Han, Ya-Jing Wang, Yun-Zhi Gao, Ge-Ping Yin

Journal of Electrochemistry

By using graphitic carbon nitride nanosheet (g-C₃N₄ nanosheet) as a support,Pt/g-C₃N₄ nanosheet catalyst was fabricated by microwave assisted polylol process. The nanoparticles size,composition,structure and optical properties of Pt/g-C₃N₄ nanosheet were characterized by TEM,XRD,XPS and UV-Vis diffuse reflectance spectroscopy. Comparing with the catalytic activities toward formic acid electro-oxidation under dark and visible light illumination,the superior activity of Pt/g-C₃N₄ nanosheet catalyst was achieved under visible light illumination. This visible light-driven enhancement in the formic acid performance could be attributed to the plasmon-induced electron-hole separation on g-C₃N₄ with …

Carbon Composite Fe3O4 Nanoparticles Based Electrochemical Sensor For Hydrogen Peroxide Detection, Si-Yu Zhang, Hui-Juan Wang, Shu-Fang Li, Jian-Ying Qu

Journal of Electrochemistry

In this work, a novel hydrogen peroxide electrochemical sensor was constructed with ferroferric oxide (Fe₃O₄) magnetic nanoparticles, which demonstrated good electrocatalytic activity for hydrogen peroxide. There existed a good linear relationship between the concentration of hydrogen peroxide and the oxidation peak current in the range of 1.00 × 10^-6 ~ 1.00 × 10^-3 mol·L^-1 (R = 0.9980) with the detection limit of 6.60 × 10-7 mol·L^-1. The sensor exhibited good anti-interference ability, high reproducibility and stability.

Simulation Of Fractal Growth On Metal Wire Electrode, Li-Feng Ding, Pei-Yuan Mao, Jun Cheng, Yu-Lan Niu, Yu-Hao Wen, Wei Chen

Journal of Electrochemistry

During processes of metal electrodepostion, there exist many complex morphological forms such as dendritic growing in the cathode deposited metal edge, which will seriously affect the quality of the electrodeposited product and current efficiency during machining. Investigations on dendritic crystal growing process and morphology could help controlling growth of electrolysis precipitate. In this work, Python and Matlab softwares were used, and the model of parallel electrode electrodeposition was established based on the diffusion-limited aggregation (DLA) model. By analyzing the law of fractal growth at different conditions of the particles number, probability, electrode spacing, the movement step length and orientation drift, …

Lead Modified Nanoporous Platinum Electro-Catalysts For Formic Acid Oxidation, Yuan-Yuan Zhang, Qing-Feng Yi, Ge-Kun-Kun Zuo, Tao Zou, Xiao-Ping Liu, Xiu-Lin Zhou

Journal of Electrochemistry

Platinum (Pt) catalysts modified by other suitable metals significantly enhance their electrochemical activities for formic acid oxidation. In this work, a titanium-supported nanoporous network platinum (nanoPt/Ti) electrode was prepared using a hydrothermal method. The as-prepared nanoPt/Ti electrode was modified with a certain amount of lead by using cyclic voltammetry for different scan cycle numbers (n), namely, n = 10, 15, 20 and 30, to synthesize the novel lead-modified nanoporous Pt (nanoPb_(n)-Pt/Ti) electrodes. Electro-oxidation of formic acid on these electrodes was studied with cyclic voltammetry (CV), chronoamperometry and chronopotentiometry in sulfuric acid solution. CV curves showed that both nanoPt/Ti …

Chemical Stability Investigations Of Catalyst Layer In Pemfc, Yan-Yan Gao, Ming Hou, Yong-Yi Jiang, Dong Liang, Jun Ai, Li-Min Zheng

Journal of Electrochemistry

This work was intended to study the effect of free radicals on the chemical stability of catalyst layer via ex situ accelerated stress test (AST). Fenton reagent was used as the free radical provider in this research. Apart from the decomposition of Nafion in catalyst layer, the agglomerated Pt nanoparticles and the corroded carbon support were also observed after being treated in Fenton reagent for 100 h. Firstly, the existence of fluoride (F) ions evidenced the chemical decomposation of Nafion after being attacked by trace radical species, which was supported by the intensity decrease in the C-F stretching and vibration …

Super‐Resolution Imaging Of Amyloid Structures Over Extended Times By Using Transient Binding Of Single Thioflavin T Molecules, Kevin Spehar, Tianben Ding, Yuanzi Sun, Niraja Kedia, Jin Lu, George R. Nahass, Matthew D. Lew, Jan Bieschke

Electrical & Systems Engineering Publications and Presentations

Oligomeric amyloid structures are crucial therapeutic targets in Alzheimer's and other amyloid diseases. However, these oligomers are too small to be resolved by standard light microscopy. We have developed a simple and versatile tool to image amyloid structures by using thioflavin T without the need for covalent labeling or immunostaining. The dynamic binding of single dye molecules generates photon bursts that are used for fluorophore localization on a nanometer scale. Thus, photobleaching cannot degrade image quality, allowing for extended observation times. Super‐resolution transient amyloid binding microscopy promises to directly image native amyloid by using standard probes and record amyloid dynamics …

Chemical Investigation Of Bioactive Marine Extracts, Selam Hagos

USF Tampa Graduate Theses and Dissertations

Natural products have been a fundamental source of medicinal scaffolds for decades; with sixty percent of marketed drugs. Many synthetic chemists are focused on synthesizing potent and nontoxic compounds for pharmaceutical targets, however, nature is still proving to be a source of new bioactive compounds. Produced by the host organism for defense, reproduction and communication, secondary metabolites also demonstrate promising bioactivity against human pathogens. Hence, natural product chemists continue their quest for new leads.

As a continuation of these efforts, this thesis attempts to explore fungi and sponges for new chemistry, and ultimately, new drug candidates. Antarctica is largely untapped; …

Game Of Frontier Orbitals: A View On The Rational Design Of Novel Charge-Transfer Materials, Maxim Vadimovich Ivanov, Scott A. Reid, Rajendra Rathore

Chemistry Faculty Research and Publications

Since the first application of frontier molecular orbitals (FMOs) to rationalize stereospecificity of pericyclic reactions, FMOs have remained at the forefront of chemical theory. Yet, the practical application of FMOs in the rational design and synthesis of novel charge transfer materials remains under-appreciated. In this Perspective, we demonstrate that molecular orbital theory is a powerful and universal tool capable of rationalizing the observed redox/optoelectronic properties of various aromatic hydrocarbons in the context of their application as charge-transfer materials. Importantly, the inspection of FMOs can provide instantaneous insight into the interchromophoric electronic coupling and polaron delocalization in polychromophoric assemblies, and therefore …

Co3(Hcoo)6@Rgo As A Promising Anode For Lithium Ion Batteries, Heng Jiang, Jing-Min Fan, Ming-Sen Zheng, Quan-Feng Dong

Journal of Electrochemistry

Metal–organic framework(MOF) is a kind of novel electrode materials for lithium ion batteries. Here, a composite material Co₃(HCOO)₆@rGO was synthesized for the first time by in situ loading of Co₃(HCOO)₆ on rGO (reduced oxide graphene) through a solution chemistry method. As an anode material for lithium ion batteries, it exhibited an excellent cycle stability as well as a large reversible capacity of 926 mAh·g^-1 at a current density of 500 mA·g^-1 after 100 cycles within the voltage range of 0.02 ~ 3.0 V vs. Li/Li⁺ with a good rate capability. …