Physical Sciences and Mathematics Commons^™

Controlled Electrochemical Synthesis Of Single One-Dimensional Metal Nanochains Across Microgap Electrodes., Amareshwari Konutham

Electronic Theses and Dissertations

This study mainly focuses on the fabrication of single one dimensional (1D) NP chains across the 5-micron gap of Au two electrode devices (TED). This has been achieved by electrochemical deposition of Ag onto the two electrodes, soaking the TED in 0.1 M Cetyltrimethyl ammonium bromide for 2-3 hours, and then close monitoring of the current as a function of time while a voltage across the two Ag coated Au electrodes in air. One dimensional Ag nanoparticle chain formation occurred by oxidation of Ag to Ag⁺ at the positive electrode followed by movement of Ag⁺ ions to the …

Determination Of Iron Content In Water, Sreenivasareddy Annem

All Capstone Projects

An easy, efficient and safe method was developed to determine iron in water samples. The method is an Iron Cell Test kit from Spectroquant in which firstly all iron ions are reduced to iron (II) ions by ascorbic acid. In a thioglycolate buffered medium, iron (II) reacts with a triazine derivative to form a purple complex that is determined photometrically. Calibration curve of iron standards was done with concentrations of 0.50, 1.0, 2.0, 3.0 and 4.0 ppm and it gave a R2 value of 0.9989 and straight line equation y=0.4749x-0.046. Iron analysis was done on two sets of water samples. …

Method Development For Analysis A Of Phthalates S By Hplc, Uma Ranganadham

All Capstone Projects

The purpose of this study is to develop an analytical method for determining the concentration of dialkyl phthalates as part of a larger study of phthalate degrading bacteria. Specifically, bacteria isolated from polyaromatic hydrocarbon contaminated riverine sediment are being determined for their proficiency in degrading dimethyl phthalate, diethyl phthalate, and dibutyl phthalate." HPLC instrument was used for analysis of these phthalate derivatives. A reversed phase isocratic and gradient elution and UV detection method was used for the individual and simultaneous determination of these phthalate derivatives. HPLC was carried out using a C18 column and spectrophotometric detection at 230nm. An isocratic …

Magnetic Nanostructure Application In Sers Detection Of Melatonin And Resonance Raman Characterization Of Binding Of Catechol Moieties With Antibiotic, Siqi Sun

USF Tampa Graduate Theses and Dissertations

Raman spectroscopy provides characteristic peaks of the target molecules that can be observed with appropriate laser, spectrometer and detector. These characteristic peaks can reveal ‘fingerprint’ information of a molecule even in a myriad of cases and combinations. It makes Raman spectroscopy a highly sensitive and selective analytical technique. Raman spectroscopy has a variety of chemical, environmental and biological applications. In this dissertation, modified Raman method are applied in life sciences and pharmaceutical studies.

The major challenge against development of Raman spectroscopy is how to improve the intensity of Raman signal. Surface Enhance Raman Scattering (SERS) and resonance Raman(RR) are utilized …

Analytical Methods To Support Design And Optimization Of Protein Drug Conjugate: Focusing On Haptoglobin-Hemoglobin Complex As A Drug Carrier, Shengsheng Xu

Doctoral Dissertations

Acquired immunodeficiency syndrome (AIDS) remains one of the most serious public health challenges and a significant cause of mortality for certain populations. Despite the large number of antiretrovirals (mostly nucleotide and nucleoside analogs) developed in the past two decades, the inability of small molecule therapeutics to target HIV reservoirs directly creates a significant obstacle to their effective utilization. Indeed, achieving the desired therapeutic effect in the absence of the effective targeted delivery must rely on dosage escalation, which frequently causes severe toxicity. This problem may be solved by conjugation of antiretroviral agents to endogenous proteins (e.g., hemoglobin haptoglobin complex) that …

Mechanistic Studies Of Proton Gradient-Driven Protein Translocation By Droplet-Interface Bilayer Techniques, En-Hsin Lee

Doctoral Dissertations

Transmembrane proton gradient plays a fundamental role in protein translocation across cellular membranes, including the transport of secreted enzymes from bacterial pathogens into host cells. Much attention has been devoted to understanding the machinery of such delivery and how it functions. Over the past decade, translocation of anthrax toxin has been widely studied not only because of its central role in the deadly pathogenesis of Bacillus anthracis, but also because that it is one of the most tractable toxins and thus serves as an attractive model for studying the translocation machinery that is dependent on proton gradient across membrane. …

Preparation Of Au/Ag Nanoshells Through A Galvanic Replacement Reaction, Elizabeth Maschmeyer

All Capstone Projects

It generally requires solid metal templates of hollow metal structures with uniform morphology by the present galvanic replacement mediated-growth approaches. In this project report, we present a new and simple approach for the controllable synthesis of Au/Ag alloy nanoshells (NSs) by applying galvanic replacement reaction on hollow Ag template in the presence of gold salt. High quality thiol-coated spherical shape Au/Ag NSs were produced via this new synthetic approach and the hollow interior of the Ag template is very well preserved during the galvanic replacement reaction. Plasmonic property measurements reveal that Au/Ag NSs exhibit strong absorption peak and more importantly, …

Synthesis Of Au/Ag, Pd/Ag And Pt/Ag Nanoparticles By Galvanic Replacement Reaction, Sunnith Kumar Admala

All Capstone Projects

In recent years, galvanic replacement reactions have been successfully employed to produce bimetallic nanoparticles of a range of shapes, yet to date very few efforts have been devoted to develop methods for synthesizing smaller (<10nm) M/Ag; M=Au, Pt, Pd alloy particles using Ag hollow particles as sacrificial template. In this research work, we investigated new approach for the controllable synthesis of Au/Ag, Pd/Ag, and Pt/Ag alloy nanoparticles by applying galvanic replacement reaction on hollow Ag template in the presence of gold, palladium, and platinum salts. According to TEM analysis, the sizes of Au/Ag, Pd/Ag, and Pt/Ag alloy particle are 7.0±1.6 nm, 6.0±1.2 nm, and 3.0±0.8 nm, respectively. According to the study of optical property measurements on Ag hollow samples with increasing Au, Pt, and Pd content, it was observed that surface plasmon resonance peaks of the Au/Ag particles prepared with higher concentrated HAuCl4 solutions absorb at longer wavelengths and are red-shifted compared to the surface plasmon resonance of Ag hollow template. In the case of adding K2PdCl4 to Ag hollow sample resulted in blue shift of surface Plasmon resonance peaks for initial addition of palladium salt and further addition of K2PdCl4 caused the Plasmon peaks to diminish. Interestingly, our attempt to make Pt/Ag particle by reacting Ag hollow particles with various amounts of K2PtCl4 revealed that resulting alloy particles could still exhibit surface Plasmon resonance peaks for higher Pt content. Usually Pt and Pd nanoparticles do not exhibit surface plasmon resonance peaks in the visible spectrum. This work provides a model for a design of M/Ag; M=Au, Pt, Pd alloy particles, where combining Ag hollow samples with increasing amounts of Au, Pt, and Pd can provide successful execution of tenability of surface plasmon resonance.

Redox And Spectroscopic Properties Of Protonated Species Of Iron Porphyrin Nitroxlys And Their Analogues, Md. Hafizur Rahman

Dissertations (1934 -)

Nitrite reduction to ammonia or nitrous oxide involves a series of electron transfer and protonation steps which are carried out by assimilatory or dissimilatory nitrite reductases. In the assimilatory process, nitrite incorporated into the biomass while in the dissimilatory process, it is excreted from the cell and the reaction is a source of energy. The complexes that will be studied in this work are models for assimilatory (siroheme) and dissimilatory (heme d1 ) nitrite reductases. Iron porphyrin nitrosyls were reduced in the presence of weak acids such as phenol and substituted phenols. Voltammetric techniques such as cyclic and rotating ring …

Manipulating The Optical Properties Of Hollow Pd/Ag And Pt/Ag Nanoparticles Synthesized By Galvanic Replacement Reaction, Salvador Alcantar

All Capstone Projects

Considerable efforts have recently been devoted to the fabrication of metallic nanostructures on account of their tunable morphologies which can lead to new and fascinating optical properties. These properties of a metallic nanostructure are most determined by their size, shape, composition and structure. Hollow metallic nanostructures have attracted much interest as their surface plasmonic properties and catalytic activities are completely different from those of solid nanoparticles. Galvanic replacement reaction (GRR) was known to be a powerful synthetic technique for converting solid metal nanostructures into hallow ones. These hollow nanostructures have high specific surface area, low density, use less material and …

Library Of Microcrystalline Tests For Novel Psychoactive Substances, Matthew Quinn, Michael Cain Jr., Monica Joshi

Chemistry Faculty Publications

A microcrystalline test is a precipitation reaction between a drug and a reagent, forming an insoluble drug-reagent complex that is unique to that specific test. These tests are quick, requiring minimal sample preparation and can be non-destructive. Therefore, they can be used as preliminary and confirmatory tests with expertise. Microcrystalline tests are one of the oldest analytical chemistry practices and their use for classic drugs such as cocaine, heroin and amphetamines is well-documented. However, there is very limited research on microcrystalline tests for the novel compounds encountered by law enforcement today. This research is an effort to increase understanding and …

In Situ Arsenic Speciation Using Surface-Enhanced Raman Spectroscopy, Mingwei Yang

FIU Electronic Theses and Dissertations

Arsenic (As) undergoes extensive metabolism in biological systems involving numerous metabolites with varying toxicities. It is important to obtain reliable information on arsenic speciation for understanding toxicity and relevant modes of action. Currently, popular arsenic speciation techniques, such as chromatographic/electrophoretic separation following extraction of biological samples, may induce the alternation of arsenic species during sample preparation. The present study was aimed to develop novel arsenic speciation methods for biological matrices using surface-enhanced Raman spectroscopy (SERS), which, as a rapid and non-destructive photon scattering technique. The use of silver nanoparticles with different surface coating molecules as SERS substrates permits the measurement …

Cathodic Electrochemiluminescence Of Meso-Tetra(4-Sulfophenyl)Porphyrin/Potassium Peroxydisulfate System, Yan-Fenga Wang, Dia Luo, Duo-Liang Shan, Xiao-Quan Lu

Journal of Electrochemistry

A new electrochemiluminescence (ECL) system in aqueous solution was constructed by using meso-tetra(4-sulfophenyl)porphyrin (TSPP) as a luminophoreand potassium peroxydisulfate (K2S2O8) as a reductive–oxidative coreactant. Upon sweeping from 0 V to -1.5 V, two cathodic ECL peaks were found simultaneously. One appeared at -0.8 V, which is corresponding to the reduction of TSPP, another at -1.2 V, that is attributed to the reduction of K2S2O8. And methylene blue could quench the ECL of TSPP effectively. In accordance with the linearity between quenching efficiency and the concentration of methylene blue, a method to determine methylene blue was established. The ECL mechanism was …

Detection Of Tetracyclines In An Anaerobic Waste Digester Using Solid Phase Extraction And High-Performance Liquid Chromatography Mass Spectrometry, Courtney Cruse

Mahurin Honors College Capstone Experience/Thesis Projects

Antibiotics are introduced to livestock to encourage growth and for the treatment of diseases. These antibiotics are not completely metabolized by swine, and thus these antibiotics are excreted with their waste. This poses a potential risk to human health as these antibiotics, a potential link to antibiotic resistant bacteria, then enter the surface water, ground water, and soil. In collaboration with the US Department of Agriculture (USDA) in Bowling Green, Kentucky, this research is concerned with analyzing the degradation of tetracyclines in swine waste from an anaerobic digester. Waste samples obtained from a digester and swine waste at the USDA …

Evolution Of Cu2o Morphology During Copper Corrosion In The Presence Of Gamma-Radiation, Arielle M. Jean

Electronic Thesis and Dissertation Repository

In this work, experiments were carried out in order to develop a mechanistic understanding of the corrosion of copper metal in limited water volumes under gamma-radiation. When exposed to gamma-radiation, water decomposes into chemically reactive oxidizing and reducing species. Under a continuous radiation flux, the concentrations of the radiolytically produced oxidants eventually reach a pseudo-steady state that can influence the corrosion kinetics of metallic surfaces.

The evolution of the surface morphology during water droplet corrosion of copper in the presence of gamma-radiation was investigated as a function of irradiation time and pH. The oxide growth kinetics were studied by measuring …

Species Identification Of Necrophagous Insect Eggs Based On Amino Acid Profile Differences Revealed By Direct Analysis In Real Time-High Resolution Mass Spectrometry, Justine E. Giffen, Jennifer Y. Rosati, Cameron M. Longo, Rabi A. Musah

Publications and Research

The colonization of decomposing remains by necrophagous insects such as blow flies is of forensic importance because the progression through the various stages of insect development can be correlated to time of death. The ability to infer this information hinges on accurate determination of the fly species that are associated with the entomological evidence collected. This evidence can include eggs, larvae, pupae, and puparial casings. Determination of the egg’s identity is particularly challenging because the eggs of multiple species are morphologically very similar. We report here that the species identity of fly eggs can be determined from their chemical fingerprint …

The Identification Of Volatile Organic Compounds From Synthetic Cathinone Derivatives For The Development Of Odor Mimic Training Aids, Vanquilla Shellman Francis

FIU Electronic Theses and Dissertations

Methylone, Ethylone, Methylenedioxypyrovalerone (MDPV), and α-Pyrrolidinopentiophenone (α-PVP) collectively referred to as bath salts are a new trend of illicit substances known as synthetic cathinones. Designed by chemically modifying the core structure of the compound cathinone, synthetic cathinones became prevalent within the United States around the mid-2000s. As a cheap and less controlled alternative to methylenedioxymethamphetamine (MDMA, ecstasy), it has become heavily abused, prompting emergency scheduling by federal regulators. Although regulations have been placed to halt incoming traffic of these drugs, lack of ground efforts still leave a large percentage of bath salts available.

This study is two-fold, as it seeks …

Evaluation Of A Filtration Sorbent For Remediation Of Arsenic In Groundwater, Clement Do

Electronic Theses, Projects, and Dissertations

A commercially available product, PURA PhosLock, was identified and evaluated for use as a sorbent to remove dissolved arsenic (As) from drinking water. Although marketed as a product to remove phosphate in aquaria, it is composed of iron oxide hydroxide (i.e., FeO(OH)), which is also known to adsorb dissolved As species from water. Arsenic was measured using standard methods and Graphite Furnace Atomic Absorption Spectroscopy. A first rough filtration test was performed to see if the PhosLock adsorbed As well. About 50 g of PhosLock was used to filter 10 L of tap water containing 100 ppb As. No detectable …

Detection Of Cathinone And Mephedrone In Plasma By Lc-Ms/Ms Using Standard Addition Quantification Technique, Theron W. Ng-A-Qui

Student Theses

Designer drugs are structural analogs of Drug Enforcement Agency (DEA) Schedule I and II substances. They are synthesized to mimic the effects of illegal drugs of abuse and to bypass the provisions of drug regulations. Despite the increased availability of designer drugs, few studies have focused on specific analytical extraction techniques for their detection and quantification in biological samples. Solid phase extraction (SPE) is the most commonly used technique for sample preparation. The purpose of this study is to evaluate the extraction efficiency of the various SPE columns with different sorbent materials for two designer drugs, cathinone and mephedrone in …

Development Of Luminescent Quantum Dot-Enabled Nano- And Microplatforms For Multiplex Detection Of Biomarkers, Kristen S. Williams

University of New Orleans Theses and Dissertations

Luminescent semiconductor quantum dots (QDs) are extensively researched for use in biological applications. They have unique optical and physical properties that make them excellent candidates to replace conventional organic dyes for cellular labeling, multiplexing, nucleic acid detection, and as generalized probes. The primary focus of this dissertation was to utilize quantum dots for improvement in immunoassays. Specifically, atherosclerosis biomarkers were detected simultaneously in an effort to demonstrate advances in early detection diagnostics.

Quantum dot-antibody bioconjugates were prepared by encapsulation into mesoporous silica and functionalized with thiol and amine groups to enable bioconjugation. Functionalization of the mesoporous silica quantum dot composites …

Study Of Selectivity In Extraction, Separation, And Detection On Drugs Using Gas Chromatography, Anumeha P. Muthal

Seton Hall University Dissertations and Theses (ETDs)

The selectivity of a method is defined by its ability to determine a particular analyte without interference in a complex mixture. Selectivity in gas chromatography (GC) can be obtained at different points in the analysis including the sample preparation, sample introduction, separation on column and detection. In GC, the first dimension of selectivity can be obtained in sample preparation; the second dimension in chromatographic separation and the third dimension in detection. This research focuses on the relationships between selectivity in these different dimensions, studied using some non-steroidal anti-inflammatory drugs, glucocorticoids, fatty acid methyl esters and polycyclic aromatic hydrocarbons. Recent methodologies …

Apparent Retention Volume Variation With Flow Rate Change In High Performance Liquid Chromatography, Susanne Buntz Erz

Seton Hall University Dissertations and Theses (ETDs)

Recent studies have demonstrated noticeable flow rate dependency of the chromatographic zone retention volume with respect to migration within the empty capillary. This appears to be the result of superposition of asymmetric lateral diffusion and of the laminar flow profile. Although these effects have been studied on empty capillaries, in the presence of the packed column, the retention shift may be insignificant relative to the adsorption-based retention of the analytes. In the case of fast and ultrafast HPLC with short capillary columns, the effect of extra-column caused variation in the analyte retention may constitute an increase of up to 120 …

Mapping Analyte-Signal Relations In Lc-Ms Based Untargeted Metabolomics, Nathaniel Guy Mahieu

Arts & Sciences Electronic Theses and Dissertations

The goal of untargeted metabolomics is to profile metabolism by measuring as many metabolites as possible. A major advantage of the untargeted approach is the detection of unexpected or unknown metabolites. These metabolites have chemical structures, metabolic pathways, or cellular functions that have not been previously described. Hence, they represent exciting opportunities to advance our understanding of biology. This beneficial approach, however, also adds considerable complexity to the analysis of metabolomics data - an individual signal cannot be readily identified as a unique metabolite. As such, a major challenge faced by the untargeted metabolomic workflow is extracting the analyte content …

Development Of Neurotensin-Based Radiopharmaceuticals For Neurotensin-Receptor-1-Positive Tumors Targeting, Yinnong Jia

Theses & Dissertations

The neurotensin receptor 1 (NTR1) is overexpressed in many cancers, due to its role as a growth pathway. These NTR1-positive cancers include pancreatic, colon, prostate and breast cancers. In the radiopharmaceutical field, the overexpression of NTR1 in cancer has prompted the development of NTR1-targeted diagnostics and therapeutics. The neurotensin (NT) peptide exhibits low nanomolar affinity for NTR1 and has been the paradigm for NTR1-targeted agents. Since the 1980’s, radiolabeled NT analogs have been developed and evaluated for targeting NTR1-positive cancers. Since native NT is rapidly degraded in vivo by a variety of peptidases, a tremendous amount of effort has been …

Ion-Specific Ice Recrystallization Provides A Facile Approach For The Fabrication Of Porous Materials, Shuwang Wu, Chongqin Zhu, Zhiyuan He, Han Xue, Qingrui Fan, Yanlin Song, Joseph S. Francisco, Xiao Cheng Zeng, Jianjun Wang

Xiao Cheng Zeng Publications

Ice recrystallization is of great importance to both fundamental research and practical applications, however understanding and controlling ice recrystallization processes remains challenging. Here, we report the discovery of an ion-specific effect on ice recrystallization. By simply changing the initial type and concentration of ions in an aqueous solution, the size of ice grains after recrystallization can be tuned from 27.4±4.1 to 277.5±30.9 mm. Molecular dynamics simulations show that the ability of the ion to be incorporated into the ice phase plays a key role in the ultimate size of the ice grains after recrystallization. Moreover, by using recrystallized ice crystals …

Improved Sample Utilization In Thermal Ionization Mass Spectrometry Isotope Ratio Measurements: Refined Development Of Porous Ion Emitters For Nuclear Forensic Applications, Matthew Louis Baruzzini

Doctoral Dissertations

The precise and accurate determination of isotopic composition in nuclear forensic samples is vital for assessing origin, intended use and process history. Thermal ionization mass spectrometry (TIMS) is widely accepted as the gold standard for high performance isotopic measurements and has long served as the workhorse in the isotopic ratio determination of nuclear materials. Nuclear forensic and safeguard specialists have relied heavily on such methods for both routine and atypical efforts. Despite widespread use, TIMS methods for the assay of actinide systems continue to be hindered by poor ionization efficiency, often less than tenths of a percent; the majority of …

Surface Modification Of Pillar Array Systems For Chromatography And Fluorescence Enhancement, Danielle Ruth Lincoln

Doctoral Dissertations

Thin-layer chromatography offers many advantages in the world of chemical separations due to its ease of use, high sensitivity, range of applicability, and multiplex capability. However, this technique is succeptible to band broadening effects that limit its efficiency. Attempting to resolve these effects by decreasing particle size causes a decrease in mobile phase velocity which creates its own band broadening via longitudinal diffusion. However, pillar array systems on the micro- and nanoscale have been shown as useful analogues to thin-layer chromatography which mitigate the efficiency concerns associated with the method.

The work within this dissertation is concerned with the modification …

Utilizing Nanostructures And Nano-Mechanics For Sensitive Analyte Detection Via Surface Enhanced Raman Spectroscopy (Sers) And Micro-Cantilever Sensing Platforms, Ryan Andrew Wallace

Doctoral Dissertations

The purpose of this dissertation is to present the effective utilization of nano-structures and nano-mechanics in conjunction with surface enhanced Raman spectroscopy (SERS) and micro-cantilever (MC) mechanical sensors for sensitive analytical detection. One of the most important attributes an Analytical Chemist can possess is the ability to develop and efficiently use the tools provided to obtain precise and accurate information that can be effectively communicated. The following is a brief outline of the background concepts and studies that will be present herein.

A discussion of SERS will be presented in which the history and concepts behind the technique will be …

Fundamental Studies Of Metal Ion Extraction Into Ionic Liquids By Macrocyclic Polyethers, James Lee Wankowski

Theses and Dissertations

The liquid-liquid extraction (LLX) of metal ions from aqueous media into ionic liquids (ILs) by macrocyclic polyethers has proven to be an efficient and selective, but complex approach to their separation. Partitioning in these systems has previously been described using a so-called ‘three-path’ model comprising three distinct extraction pathways: neutral complex / ion pair extraction, exchange of the IL cation for a metal-extractant complex, and exchange of the metal ion for a hydronium ion bound to the extractant. The balance of these three paths has been reported to be affected by several characteristics of the LLX system, including the structure …

The “Apparent” Diffusion Coefficient Of Electrons Through A Nafion Membrane, Marissa Kayle Reynolds

Graduate Theses and Dissertations

The hydrogen/oxygen fuel cell is a greener, more efficient energy solution. However, there are many problems with the fuel cell including storage, infrastructure, cost, the oxygen reduction reaction, and the durability of the proton exchange membrane (PEM). The PEM is not only used as the electrolyte for the cell but also as a physical barrier between the anode and the cathode. The integrity of this membrane is crucial to the functioning of the fuel cell. This thesis will examine using ferricyanide as a probe molecule for diagnostic experiment of Nafion membrane integrity. Using hydrodynamic voltammetry with a rotating disk electrode …