Chemistry Commons^™

Univariate Optimization Of Dispersive Liquid-Liquid Microextraction For Preconcentration Of Lead From Environmental Matrices, Samawah Region Prior To Quantification Using Flame Atomic Absorption Spectroscopy, Zaman Sahb Mehdi, Saher A. Ali Alshamkhawy

Al-Bahir

In this work, a procedure based on dispersive liquid₋liquid microextraction for lead (Pb) preconcentration and quantification in an environmental matrix by flame atomic absorption spectroscopy (FAAS) was applied. A case-study approach was chosen to obtain further in-depth information on the Pb levels. The green chemistry principles have been applied for the pretreatment and preparation of real samples by focusing on some features such as the volume of reagents/sample, employ of energy efficient equipment, and production of waste. A univariate strategy was utilized to achieve the optimum extraction conditions. 1750 µL of acetonitrile containing 100 µL of carbon tetrachloride, were rapid …

Papain-Catalyzed Synthesis Of Oligolysine In Low-Water Organic Reaction Media, Lakshmi Priya Ravikrishna, Krishnamurthi Tamilarasan, Vairamani Mariappanadar, Shubhender Kapila, Mathur Rajesh

Chemistry Faculty Research & Creative Works

Oligopeptides of l-lysine have the potential for applications in various scientific and technical areas. The number of residues in polycationic compounds such as oligolysine is also reported to have an effect on its biological properties. Hence, there is a necessity for developing efficient oligolysine synthesis methods where the oligopeptide dispersity can be tailored, along with optimum yield values. The ability of proteases to reverse their proteolytic activity to synthesize peptides has been reported in the literature. However, protease-catalyzed synthesis of oligopeptides of basic amino acids such as lysine in aqueous buffers is hindered by unfavorable thermodynamics. In this work, a …

Amperometric Bio-Sensing Of Lactate And Oxygen Concurrently With Local Field Potentials During Status Epilepticus, Eliana Fernandes, Ana Ledo, Greg A. Gerhardt, Rui M. Barbosa

Neurology Faculty Publications

Epilepsy is a prevalent neurological disorder with a complex pathogenesis and unpredictable nature, presenting limited treatment options in >30 % of affected individuals. Neurometabolic abnormalities have been observed in epilepsy patients, suggesting a disruption in the coupling between neural activity and energy metabolism in the brain. In this study, we employed amperometric biosensors based on a modified carbon fiber microelectrode platform to directly and continuously measure lactate and oxygen dynamics in the brain extracellular space. These biosensors demonstrated high sensitivity, selectivity, and rapid response time, enabling in vivo measurements with high temporal and spatial resolution. In vivo recordings in the …

Monodispersed Cu-Tcpp/Cu2O Hybrid Microspheres: A Superior Cascade Electrocatalyst Toward Co2 Reduction To C2 Products, Zi-Xuan Wan, Aidar Kuchkaev, Dmitry Yakhvarov, Xiong-Wu Kang

Journal of Electrochemistry

The electrochemical conversion of carbon dioxide (CO₂) into valuable chemicals is a feasible way to mitigate the negative impacts of overmuch CO₂ emissions. Porphyrin-based metal organic frameworks (MOFs) are expected to be used for selective and efficient electrochemical CO₂ reduction (ECR) with porous structure and ordered active sites. Herein, we report the synthesis of a monodispersed and spherical organic/inorganic hybrid Cu-TCPP@Cu₂O electrocatalyst composed of Cu-TCPP (TCPP=tetrakis (4-carboxyphenyl) porphyrin) and Cu₂O, where TCPP plays significant roles in regulating the morphology. In-situ formed Cu during ECR process in combination with Cu-TCPP (Cu-TCPP@Cu) can suppress …

Development Of Microfluidic Thermal Gel Electrophoresis For Biological Analysis, Mario Ambrocio Cornejo

Wayne State University Dissertations

ABSTRACTDEVELOPMENT OF MICROFLUIDIC THERMAL GEL ELECTROPHORESIS FOR BIOLOGICAL ANALYSIS by MARIO AMBROCIO CORNEJO May 2024 Advisor: Dr. Thomas H. Linz Major: Chemistry (Analytical Chemistry) Degree: Doctor of Philosophy The molecular biology that takes place within cells is vital to the over function of an organism. Healthy cellular function is crucial to a wide web of interconnected processes that need to be balanced and regulated. When these processes become abnormal, disease states are developed. The mapping of biological networks has led to the development of gene therapy and more accurate diagnostic tests. However, there are still vital biomolecules that due to …

Visible Light Photocatalysis With Quantum Dot Gel For Organic Synthesis, Daohua Liu

Wayne State University Dissertations

This dissertation presents metal chalcogenide quantum dots (QDs), a group of emerging visible light photocatalysts, for unique organic chemical transformations that are impossible using conventional molecular photocatalysts. The first part of this dissertation focuses on the comparison between ligand-capped CdS QD and CdS gel. CdS QD gel is a three-dimensional network of interconnected QD. CdS gels were found to show more facile charge transfer with substrates than QDs, due to the partial removal of ligands from its surface during gelation. Our study showed that the photocatalytic activity of CdS gels was indeed superior to trioctylphosphine (TOP)- and thioglycolic acid (TGA)-capped …

Solution Combustion Synthesis And Characterization Of Fumarolic Mineral Dolerophanite, Copper (Ii) Oxide Sulfate, Eric J. Cyganowski

Chemistry & Biochemistry Theses - Archive

Dolerophanite Cu₂OSO₄ is a rare mineral found almost exclusively in the fumaroles of volcano systems and is sensitive to temperature and humidity conditions. It has a monoclinic C2/m crystal structure characterized by two-dimensional layers composed of sulfate anions dispersed amongst copper (II) oxide backbones. There has been recent interest in dolerophanite due to the magnetic properties of its Kagome-like lattice as well as its potential use as a photocatalyst or Li-ion battery electrode. Literature on the material however has been limited by the available synthesis strategies. As such, this thesis work presents a novel strategy …

Unusual Eluents, Small Systems, And Digital Signal Processing For Highly Efficient Greener Separations, Troy T. Handlovic

Chemistry & Biochemistry Dissertations - Archive

Separation science is a rapidly evolving field, where routine analyses are now done at speeds and efficiencies not thought to be possible several years ago. The tangential field of green analytical chemistry is evolving at an even faster rate and can be considered to be in its infancy stage. As green analytical chemistry is better understood, the greenness of a method will be considered during standard method development just as resolution, sensitivity, and efficiency are considered now. The first portion of this dissertation focuses on the development of mathematical and pragmatic methods to minimize the analytical method greenness score, and …

Development Of Vacuum-Assisted Headspace High-Capacity Solid-Phase Microextraction For The Determination Of Semi-Volatile Compounds From Samples At Lower Temperatures, Shannon L. Thomas, Kevin A. Schug, Colton Myers, Jason S. Herrington, Reagan L. Miller, Anush Pabley, Frank W. Foss

Chemistry & Biochemistry Dissertations - Archive

Vacuum-assisted headspace solid-phase microextraction (Vac-HS-SPME) is a method used to increase solid-phase microextraction sampling of semi-volatile organic compounds. Three studies were conducted using Vac-HS-SPME via gas chromatography - mass spectrometry (GC-MS) methods for analysis of various sample types. First, a study was performed using Vac- HS-SPME combined with a high-capacity (HC) SPME Arrow to determine the operational fundamentals and workflow necessary to achieve optimal extraction of semi-volatile compounds from a model solid matrix (Ottawa sand). The fundamentals investigated included the seals necessary to create a leak-free sampling vial under vacuum conditions; the magnitude of the vacuum exerted, and the time …

Aggregation And Oligomerization Characterization Of Ss-Lactoglobulin Protein Using A Solid-State Nanopore Sensor, Mitu C. Acharjee, Brad Ledden, Brian Thomas, Xianglan He, Troy Messina, Jason Giurleo, David Talaga, Jiali Li

Physics Faculty Publications and Presentations

Protein aggregation is linked to many chronic and devastating neurodegenerative human diseases and is strongly associated with aging. This work demonstrates that protein aggregation and oligomerization can be evaluated by a solid-state nanopore method at the single molecule level. A silicon nitride nanopore sensor was used to characterize both the amyloidogenic and native-state oligomerization of a model protein ß-lactoglobulin variant A (βLGa). The findings from the nanopore measurements are validated against atomic force microscopy (AFM) and dynamic light scattering (DLS) data, comparing βLGa aggregation from the same samples at various stages. By calibrating with linear and circular dsDNA, this study …

Investigating The Ultrafast Dissociation Dynamics Of Energetic Materials Using Femtosecond Time-Resolved Mass Spectrometry, Jacob M. Shusterman

Theses and Dissertations

Shock initiation of energetic materials produces cations and anions that can contribute to initial endothermic chemical reactions which lead to detonation. Hence, knowledge of the initial dissociation pathways of ionized energetic molecules is important for advancing the understanding of initiation mechanisms and meeting longstanding goals of the Department of Defense. Despite their potential importance, these transient charged species are difficult to detect in detonation experiments and are often ignored in molecular dynamics modeling of shocked energetic materials. However, the technique of pump-probe femtosecond time-resolved mass spectrometry (FTRMS) paired with complementary theoretical calculations can be used to elucidate initial unimolecular dissociation …

Developing Methods For Analysis Of Chiral Small Molecules And D-Amino Acid Containing Peptides, Joshua I. Putman

Chemistry & Biochemistry Dissertations - Archive

This dissertation covers the development of methods to analyze chiral small molecules and d-amino acid containing peptides. The first section covers the development of liquid chromatographic chiral screening approaches for newly synthesized chiral molecules. The next part of the dissertation covers methodologies for the analysis of d-amino acid containing peptides. Lastly the bacterial degradation of three commonly used pesticides by bacteria harvested from Colorado potato beetles (Leptinotarsa decemliniata) is presented.

Twelve new azole compounds and eleven racemic ethanolamine derivatives were synthesized. These twenty-three compounds were evaluated using eight chiral columns, four macrocylic glycopeptides, a cyclodextrin derivative …

Lead-Free Perovskite/Metal Oxide Heterojunction Photocatalyst For Sustainable Toluene Oxidation, Zakarya Hazaea

Chulalongkorn University Theses and Dissertations (Chula ETD)

An important field of study is the ecologically benign synthesis of useful compounds such as benzaldehyde and benzyl alcohol from the organic contaminant toluene. Lead-free halide perovskites are excellent options for photocatalysis due to their exceptional photoelectric properties. Nonetheless, they have notable challenges, such as fast charge recombination and ineffective charge separation. In this work, we present a simple anti-solvent technique to create a heterojunction between lead-free halide perovskite Cs2AgBiBr6 (CABB) with Cu2O and Cu-Cu2O. This combination facilitates the photocatalytic activation of C(sp3)−H bonds, which in turn increases the oxidation of toluene. The Cu2O and Cu-Cu2O creating a Z-scheme heterojunction …

Assessment Of The Extraction And Quantification Of Pfbs From Sprague Dawley Rat Adipose Tissues, Joshua O. Osaghae

Honors College Theses

Per- and polyfluoroalkyl substances (PFAS) are a group of complex synthetic chemicals that have applications ranging from automotives to consumer products. PFAS have been found to bioaccumulate in the ecosystem as their carbon-fluorine bonds are among the strongest bonds in organic chemistry. Perfluorobutanesulfonic acid (PFBS) compounds are used as surfactants in water- and stain-repellent coatings for fabrics and carpets, cleaning agents, and paints. The persistence of PFAS has led to their accumulation in sources of groundwater, making them ubiquitous drinking water contaminants of concern with evidence linking PFAS exposure to adverse health effects, including reduced kidney function, thyroid disruption, and …

Experimental And Chemical Modeling Of Applied Dc Electric Field Induced H2 – Air Axisymmetric Laminar Co-Flow Diffusion Flames With Low Carbon Impurities, Susith Dilshan Pathmasiri Gunamuni Halowitage

Graduate Theses, Dissertations, and Problem Reports (ETD)

The effect of externally applied DC electric fields on flame structure was investigated in a stationary atmospheric axisymmetric laminar H₂–Air flame with less than 100 ppm carbon equivalent impurities. Flame OH chemiluminescence signals were recorded using a UV-sensitive CCD array as a function of voltage (+10 to -10 kV) applied to a stainless-steel ring electrode placed around the burner nozzle. Changes in chemiluminescence signal are reported as a function of electrode height above the burner, airflow, and fuel composition. Significant changes in OH* distributions were observed for voltages below -5 kV. Under optimum conditions, the height of the …

Development Of Lab-On-A-Chip Platforms Incorporating A Novel Acoustic Atomization Induced Pump Based On A Vibrating Sharp Edge Capillary., Balapuwaduge Lihini Tharanga Catherine Mendis

Graduate Theses, Dissertations, and Problem Reports (ETD)

Capillary Vibrating Sharp-edge Ionization device (cVSSI device) was developed by our laboratory with a low cost and an easy fabrication procedure. The generation of small liquid droplets by this technique has been used as an ionization source for mass spectrometry analysis platforms. On usual applications incorporating the cVSSI device a syringe pump was connected to the back end of the vibrating sharp tip capillary to ensure continuous loading of sample into the capillary to sustain the ionization process at the tip end of the vibrating sharp tip capillary. We were able to observe that upon the generation of droplets the …

The Surface Chemistry And Binding Interactions Of Lignin With Polymer-Encapsulated Gold Nanoparticles Acting As Model Microplastics, Oluwaseun Ayodeji Akinsola

All Master's Theses

This study investigates the surface chemistry and molecular-level interactions between lignin, a special type of natural organic matter, and polymer-capped gold nanoparticles, shedding light on the strength of adsorption between lignin and nanoscale polymer surfaces. Specifically, the study presents a variety of nanoscale polymer surfaces displaying different charged functional groups, using layer-by-layer assembly of three polyelectrolytes (polyallylamine hydrochloride (PAH)), polyacrylic acid (PAA), and poly(diallyldimethylammonium chloride (PDADMAC)) on 90 nm citrate-stabilized gold nanoparticles (AuNPs). This approach provides a library of polymer-encapsulated AuNPs for investigating the binding interactions of lignin to nanoscale polymers via spectroscopic techniques. ζ-potential, dynamic light scattering (DLS), …

A Portable, Digital Nucleic Acid Amplification Test For Use At The Point Of Care, Bethany J. Fike

Graduate Theses, Dissertations, and Problem Reports (ETD)

Nucleic acid tests are key tools for the detection and diagnosis of many diseases. In many cases, the amplification of nucleic acids is required to reach a detectable level. Although nucleic acid tests have great success, there is a need to make nucleic acid amplification tests more accessible to a point-of-care (POC) setting for diagnosis, prognosis, and monitoring of infectious diseases. Traditionally, these tests are performed through bulk Polymerase Chain Reaction (PCR) and are monitored in real time with a change in fluorescence intensity. With these bulk testing methods, only a qualitative or semi-quantitative result is possible. For more exact …

The Role Of Sugars In Aggregation Of The Protein Kassinin, Lillie G. Waldron

Student Summer Scholars Manuscripts

The aggregation of proteins to form amyloids is implicated in several diseases such as Alzheimer’s Disease, Parkinson’s Disease, and many others. This aggregation has several stages, progressing from isolated protein molecules (monomers) to small aggregates (oligomers), which are toxic to cells, and finally to large, string-like mature aggregates. Despite this association with disease, functional amyloids, which have normal biological functions, also result from protein aggregation. Kassinin, an amphibian peptide involved in nerve signal transmission, is a model system for functional amyloid study. To compare the aggregation of functional and disease-causing amyloids, we previously synthesized a fluorine-labeled kassinin through solid-phase peptide …

Detection Of Micrornas In Blood Samples Using Biosensors For The Detection Of Early-Stage Lung Cancer, Nicholas Bruno

Honors Undergraduate Theses

Lung cancer kills more people in the U.S. a year than any other cancer. This is largely because patients often remain asymptomatic until stage 3, by which time the tumor is usually highly malignant. High radiation-producing screenings are the current method of lung tumor detection. These typically involve machinery for tumor visualization, such as computed tomography (CT) scans, positron emission tomography (PET scan), magnetic resonance imaging (MRI), and X-rays. Not only does radiation exposure from this equipment pose a risk to the patient, but any tumors detected by these scanning techniques are likely to be locally advanced. This suggests that …

Inhaling The Unseen: Exploring The Presence Of Microplastics In The Human Respiratory Tract, Kara Coffman-Rea

Graduate Research Theses & Dissertations

Microplastics (plastic pieces less than 5 mm) have emerged as a pervasive form of pollution acknowledged as a universal threat to both environmental and human health. Their small size and widespread distribution pose significant risks to marine life, terrestrial ecosystems, and ultimately human health. Microplastics have been reported in food and drink items designated for human consumption, in cosmetics and consumer goods designed for human use, and within the air we breathe, each providing an entry route for microplastics to enter the human body. Recently, microplastic particles have been detected in a variety of human tissue samples (e.g., lung tissue). …

Addressing The Effects Of Counterion Size On The Properties Of Electrochemically Doped Conjugated Polymers, Kyle Baustert

Theses and Dissertations--Chemistry

Conjugated polymers (CPs) are an emerging class of materials that are attractive for many applications due to their low cost, flexibility, and ease of processing. Both chemical and electrochemical doping of CPs is done to alter important properties such as their electrical conductivities and optical absorbances. This ability to tune their properties allows for their use in devices such as organic electrochemical transistors (OECTs) for biosensing and bioelectronics, electrochromic devices for color changing windows, as well as wearable thermoelectrics to use body heat to power wearable electronics. There are several factors that can influence the properties of doped CPs including …

Effect Of Π-Conjugated Ligands And A* Site Organic Cations On The Energetic Properties And Photovoltaic Performance Of Metal Halide Perovskites, Harindi R. Atapattu

Theses and Dissertations--Chemistry

Metal halide perovskites have gained interest in optoelectronic applications such as photovoltaics, lasers, LEDs, transistors, and photodetectors due to their excellent semiconducting properties considering their low cost. Metal halide perovskite (HP) photovoltaics have rapidly increased in power conversion efficiency (PCE), which now exceeds 25%. HPs have gained attention in these applications due to their high tolerance towards defects, long charge carrier diffusion lengths, high charge carrier mobility, high optical absorption, and bandgaps that are tunable over a large range. Even though HP photovoltaic PCEs are improved these are still not commercially available due to them showing lower stability and energy …

Dna I-Motifs: Biophysical Characterization And Structure-Property Correlation As Foundation For Functional Material Design, Alexander Minasyan

Graduate Research Theses & Dissertations

Over the past decades, nucleic acids have emerged as crucial frameworks with significance in biological systems and functional material engineering. Cytosine-rich deoxyribonucleotide sequences can form quadruplex structures a.k.a. i-motifs. Recently, i-motifs have attracted scientific interest in biological and material design areas.

In this work, we systematically investigate an effect of structured and unstructured modifications such as hairpins, stems, loops and overhangs on the kinetic and thermodynamic properties of DNA i-motifs. We demonstrate that the modifications can influence i-motif’s stability and folding/unfolding rates: thus, double stranded stems and hairpins are the best at stabilizing i-motifs and increasing kinetic rates of folding. …

Stability Of Organic Metal Halide Perovskites, S S M Tareq Hossain

Theses and Dissertations--Chemistry

Perovskites have emerged as a promising candidate for low-cost production of solar cells. However, the most critical barrier for commercialization of perovskite solar cells (PSCs) is the inadequate stability of the organic metal halide perovskites (OMHPs). The degradation of OMHPs is induced by light, heat, air, and electrical bias. The known degradation pathways involve the oxidation of I- and Sn2+, dissolution of perovskites by moisture, irreversible reactions with water, ion migration, and ion segregation. To improve the stability of OMHPs various methods are adopted, such as additive engineering, perovskite surface treatment, and composition engineering. Surface ligands are used on top …

Impacts Of Key Degradation Byproducts On Amine Scrubbing For Post-Combustion Carbon Capture, Thomas Jorgensen

Theses and Dissertations--Chemistry

The increasing atmospheric CO₂ concentration causes significant concern about global warming and its environmental impact. Industrial sectors, including power generation, transportation, and production factories, contribute most of the anthropogenic sources of CO₂ emissions. Researchers search for methods to mitigate these CO₂ emissions without compromising the benefits of industrial processes, including CO₂ capture, utilization, and sequestration (CCUS). Post-combustion carbon capture (PCCC) by amine scrubbing is the most technology ready CCUS, with various pilot-scale projects worldwide showing small-scale to fully operational plants. While researchers have made significant progress in amine scrubbing, they strive to improve the efficiency and …

Use Of Interlaboratory Studies For The Development Of Consensus-Based Criteria For The Elemental Analysis Of Electrical Tapes, Lacey M. Leatherland

Graduate Theses, Dissertations, and Problem Reports (ETD)

Tape evidence is often used in criminal cases involving violent crimes, kidnappings, improvised explosive devices (IEDs), and drug trafficking. This evidence can reveal potential links between suspects, items, or scenes. The forensic examination of electrical tape can provide investigative leads or offer support to alternative hypotheses evaluated in the courtroom. A conventional analytical scheme includes microscopic examination, Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy Energy Dispersive Spectrometry (SEM-EDS), and Pyrolysis Gas Chromatography Mass Spectrometry (Py-GC/MS). Elemental analysis of electrical tapes is commonly achieved using SEM-EDS; however, recent scientific literature suggests that this analysis can evolve from using SEM-EDS to …

Conformational Investigation Of Biopolymers Through Molecular Dynamics (Md) Simulations And In-Droplet Hdx-Ms Utilizing Cvssi, Samira Hajian Foroushani

Graduate Theses, Dissertations, and Problem Reports (ETD)

Over the last two decades, mass spectrometry (MS) has received significant interest in biological study platforms, especially in the areas of proteomics and metabolomics. With the development of soft ionization methods like electrospray ionization (ESI), mass spectrometry has emerged as a potent method for directly characterizing proteins in their native state. The recent invention of capillary vibrating sharp-edge spray ionization has opened new avenues for the study of biopolymer native structure including the usage of droplet charge tuning and in-droplet hydrogen-deuterium exchange (HDX) labeling. With this new technique comes the opportunity to study biopolymer ion structure preservation with molecular dynamics …

Analytical Methods For Monitoring Traumatic Brain Injury Biomarkers/Treatment And Pharmaceutical Residual Solvents, Olajide Philip Adetunji

Doctoral Dissertations

"The development of highly sensitive and efficient analytical methods utilizing advanced instrumentation is necessary to help improve disease diagnosis and therapeutics. A major neuro-consequence of traumatic brain injury (TBI) is oxidative stress from the generation of reactive oxygen species and the depletion of antioxidant defenses. Alteration in concentrations of certain small molecules also occurs with the disease progression and can help understand TBI pathophysiology. Two analytical methods employing liquid chromatography with tandem mass spectrometry (LC-MS/MS) were developed and validated to monitor the potential small-molecule TBI biomarkers at sub-ppb levels. Subsequently, the neuroprotective effect of an antioxidant prodrug, N-acetylcysteine amide (NACA), …

Measuring The Properties Of Rod-Shaped Bacteria By Single-Entity Electrochemistry, Ashley Tubbs

Theses and Dissertations

Antibiotic-resistant bacteria pose a significant and escalating threat to hospitals around the world, necessitating the development of rapid and sensitive detection methods. Single-entity electrochemistry has emerged as a promising approach for detecting and identifying such bacteria, and monitoring the efficacy of antibiotics in real-time. Herein, we employ the translational diffusion equation for circular cylinders to predict the collision frequency of rod-shaped bacteria, informing our experimental setup. Our work demonstrates that lab-fabricated Pt ultramicroelectrodes can sensitively detect bacteria at femtomolar concentrations under migration-controlled conditions. Further, we present a method implemented in MatLab to automate the analysis of step-like signals observed in …