Physical Sciences and Mathematics Commons^™

Automated Workflow For Redox Potentials And Acidity Constants Calculations From Machine Learning Molecular Dynamics, Feng Wang, Jun Cheng

Journal of Electrochemistry

Redox potentials and acidity constants are key properties for evaluating the performance of energy materials. To achieve computational design of new generation of energy materials with higher performances, computing redox potentials and acidity constants with computational chemistry have attracted lots of attention. However, many works are done by using implicit solvation models, which is difficult to be applied to complex solvation environments due to hard parameterization. Recently, ab initio molecular dynamics (AIMD) has been applied to investigate real electrolytes with complex solvation. Furthermore, AIMD based free energy calculation methods have been established to calculate these physical chemical properties accurately. However, …

Tunable Magnetic Coupling In Graphene Nanoribbon Quantum Dots, Peter H. Jacobse, Mamun Sarker, Anshul Saxena, Brookhaven National Laboratory, Ziyi Wang, Emma Berger, Narayana R. Aluru, Alexander Sinitskii, Michael F. Crommie

Chemistry Department: Faculty Publications

Carbon-based quantum dots (QDs) enable flexible manipulation of electronic behavior at the nanoscale, but controlling their magnetic properties requires atomically precise structural control. While magnetism is observed in organic molecules and graphene nanoribbons (GNRs), GNR precursors enabling bottom-up fabrication of QDs with various spin ground states have not yet been reported. Here the development of a new GNR precursor that results in magnetic QD structures embedded in semiconducting GNRs is reported. Inserting one such molecule into the GNR backbone and graphitizing it results in a QD region hosting one unpaired electron. QDs composed of two precursor molecules exhibit nonmagnetic, antiferromagnetic, …

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 Journal for Engineering and Pure Sciences

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 …

The Top Ten Scientific Questions In Electrochemistry, Chinese Society Of Electrochemistry

Journal of Electrochemistry

1. How to Detect or Simulate the Dynamic Structural Changes of Complex Electrochemical Interfaces under In-Situ/Operando Conditions at the Microscale, and Establish Their Relationships with Macroscopic Electrochemical Performance?
2. How to Understand and Regulate the Nucleation and Growth of Metal Lithium at the Anode, and Develop Strategies for Suppressing Dendrite Formation？
3. How to Obtain High-Performance Alkali-Metal-Ion Solid-State Electrolytes for Solid State Batteries?
4. How to Develop Aqueous Battery Systems with High Energy Density and Multi-Electron Transfer Reaction？
5. How to Rationally Design Efficient and Long-Lasting Low/Non-Platinum Electrocatalysts and Their Large-Scale Production?
6. How to Construct High-Efficiency Three-Phase Interface and Gain Insights into Enhanced Charge/Mass Transportation …

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 …

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 …

Investigating The Effect Of Relative Humidity On Organic New Particle Formation From The Dark Ozonolysis Of Biogenic Volatile Organic Compounds, Austin Callum Flueckiger

Graduate College Dissertations and Theses

Solid or liquid particulate matter suspended in the air, also known as atmospheric aerosols, are a ubiquitous component of Earth’s atmosphere. It is important to understand the chemical and physical processes that lead to the formation of these aerosols as they have an impact on climate health and human health. An important subset of atmospheric aerosols are secondary organic aerosols (SOA) that form from the gas-phase oxidation of volatile organic compounds (VOCs). VOCs can be emitted via biogenic and anthropogenic pathways, however, global estimates place biogenic sources as the major contributor. Although widely studied, some of the fundamental mechanisms that …

Geochemistry Of Rare Earth Elements In Simulated Natural Waters: Experiments And Modelling Of Precipitation, Complexation, And Bioavailability., Samantha Zulian

Theses and Dissertations (Comprehensive)

Rare earth elements (REEs) are an important part of modern technology and used for many applications. Mining, agriculture, improper recycling and medical applications can increase the concentration of these elements in surface waters. Metals in the environment including REEs can be found naturally but understanding the implications increase concentrations from anthropogenic inputs is important. REE mobility, persistence and toxicity is imperative to risk assessment as Canada begins to mine REE. Ultimately, as with other metals, the impacts of REEs in the environment should be dependent on the specific physical and chemical forms of the elements. Fractionation provides a practical method …

Role Of Relative Humidity In New Particle Formation From Ozonlysis Of Atmospheric Volatile Organic Compounds, Christopher Snyder

Graduate College Dissertations and Theses

The impact of relative humidity (RH) on organic new particle formation (NPF) from ozonolysis of biogenic volatile organic compounds (BVOCs) remains an area of active debate. Previous reports provide contradictory results indicating both depression and enhancement of NPF under conditions of moderate RH, while others ignore the potential impact. Only several reports have suggested that the effect may depend on absolute mixing ratio of the precursor volatile organic compound (VOC, ppbv). However, before any experiments could be completed, development of new methods was necessary to overcome the limitation of sampling ultrafine nanoparticles (<50 nm aerodynamic diameter) with aerosol mass spectrometry. This dissertation includes a report on a new Particle Growth Apparatus (PaGA) that artificially grows particles from as small as 17 nm to over 110nm. Considerable effort was made to identify the most suitable growth matrix (squalane) and optimize particle growth for reproducibility and sensitivity.

The PaGA was then utilized in the …

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

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 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

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 …

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

Chemistry & Biochemistry Theses

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 …

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), …

Development Of Novel Protein Digestion And Quantitation Methods For Mass Spectrometic Analysis, Yongling Ai

Dissertations

Proteins are the workhorses of biology, playing multifaceted roles in maintaining cellular function, signaling, and response to environmental cues. Understanding their abundance and dynamics is pivotal for unraveling the complexities of biological processes, which underpins the foundations of molecular and cellular biology. Accurate measurement of protein quantities provides insights into cellular homeostasis, facilitates the discovery of biomarkers, and sheds light on the molecular mechanisms of diseases, bridging the gap between the molecular intricacies of proteins and their functional consequences in health and disease. The evolution of protein quantitation methodologies, from classical colorimetric assays to sophisticated mass spectrometry-based approaches, has expanded …

Assessing The Performance Of Newly Developed Silica Nanoparticles Against Lead And Phosphate Ion Removal From Contaminated Solutions Using Adsorption Isotherm, Hasan Shamseddine, Nour Abi Aad, Rami Oweini, Ghassan Younes

BAU Journal - Science and Technology

This study investigates the removal of Lead and Phosphate ion from aqueous solution using new silica nanoparticles doped with europium (H1) which was characterized using Scanning Electron Microscopy (SEM), Dynamic Light Scattering (DLS), Fourier-transform Infrared Spectroscopy (FTIR). The aim of this research is to develop a novel adsorbent material that can efficiently remove contaminated ions from wastewater or aqueous solutions. The adsorption of lead and phosphate ion onto the silica nanoparticles is investigated, and the efficiency of this removal is evaluated. Equilibrium data analysis reveals linear fitting with Langmuir isotherm with 24.76 mg/g Lead ion uptake, while for phosphate the …

Intelligent Control Based On Bp Artificial Neural Network For Electrochemical Nitrate Removal, Xin-Wan Zhang, Guang-Yuan Meng, Li-Qiang Fang, Ding-Ming Chang, Tong Li, Jin-Wen Hu, Peng Chen, Yong-Di Liu, Le-Hua Zhang

Journal of Electrochemistry

Achieving effective control of parameters in the process of nitrate wastewater treatment is critical to electrochemical water treatment. The powerful nonlinear mapping ability, self-adaptation and self-learning ability of neural network technology can optimize the electrochemical processing. However, there are few researches in this direction. Hence, based on the test data of the electrochemical reduction of nitrate, an electrochemical prediction model was established by using the BP neural network algorithm. Considering the correlation of various parameters in the electrochemical process, the reaction time, initial nitrate nitrogen concentration, pH and current density were determined as the input layer of the BP neural …

Investigation Of Zinc And Iron In Wildflower Honey, Savannah Simpson

Honors Theses

Honey acts as a valuable food source for both animals and humans. When found in contaminated environments, there is an increased likelihood that honey samples will have high metal concentrations. It has been discovered that honey concentrations in metals can be different based on location. This experiment aims to determine the amount of two valuable metals, zinc, and iron, in various honey sources. These metals can be important to the human body because they help boost immunity and allow the body to carry out the functions required for survival. However, if these elements are present in copious quantities, then it …

Differentiation Of Human, Dog, And Cat Hair Fibers Using Dart Tofms And Machine Learning, Laura Ahumada, Erin R. Mcclure-Price, Chad Kwong, Edgard O. Espinoza, John Santerre

SMU Data Science Review

Hair is found in over 90% of crime scenes and has long been analyzed as trace evidence. However, recent reviews of traditional hair fiber analysis techniques, primarily morphological examination, have cast doubt on its reliability. To address these concerns, this study employed machine learning algorithms, specifically Linear Discriminant Analysis (LDA) and Random Forest, on Direct Analysis in Real Time time-of-flight mass spectra collected from human, cat, and dog hair samples. The objective was to develop a chemistry- and statistics-based classification method for unbiased taxonomic identification of hair. The results of the study showed that LDA and Random Forest were highly …

An Inkjet-Printed Graphene Oxide–Poly(3,4-Ethylenedioxythiophene) Poly(Styrene Sulfonate) Electrode For Nitrite Detection In Water, Budi Riza Putra, Weni Anindya, Mohamad Rafi, Ika Kartika, Yudi Nugraha Thaha, Aga Ridhova, Wulan Tri Wahyuni

Makara Journal of Science

In this study, a screen-printed electrode (SPE) for nitrite (NO₂⁻) sensing was fabricated through an inkjet printing technique using a commercial printer machine and preparing an ink composite solution containing graphene oxide (GO) and poly(3,4 ethylenedioxythiophene) poly(styrene sulfonate) (PEDOT:PSS) as conductive materials. The optimum ink materials for SPE fabrication comprised GO and PEDOT:PSS with binders that resemble the viscosity of commercial ink. The surface topography of the fabricated SPE, which was characterized using scanning electron microscopy and atomic force microscopy, showed a smoother surface compared to the commercial screen-printed carbon electrode, with conductive ink materials deposited primarily …

Integration Of Raman Spectroscopy And Python-Based Data Analysis For Advancing Neurobiological Research, Natalie E. Dunn

Doctoral Dissertations

The field of Raman spectroscopy continues to expand into biological applications due to its usefulness as a non-invasive technique that can be utilized qualitatively and quantitatively. However, the inherent weakness of Raman scattering leads to the need for each collected spectra to undergo a preprocessing step to remove noise, background drift, and cosmic rays. Biological research in particular needs large datasets due to the increased variability in samples. As datasets grow, the need to perform preprocessing on each individual spectra becomes daunting. Often, these steps are done by hand with the help of specialized software programs. Preprocessing can be accelerated …

A Noninvasive Urine-Based Method For Kidney Cancer Early Detection, Kiana Holbrook

Open Access Theses & Dissertations

Based on the traditional serological uses to obtain diagnoses of cancer and biopsy techniques, common cancer detection could be not only invasive but expensive and some tests are also unreliable. Currently, urine is one of the most frequently used and collected specimens in the clinical diagnoses. While the areas of urinalysis and metabolomic profiling has received interest in the top clinical research, there are limited components to the validity, specificity, as well as sensitivity of endogenous urine substrates to detect early stages of cancers. Although there is research showcasing that urine is impacted by age, cancer type, geographical location, and …

Towards The Quantification Of Estrone And 17Β-Estradiol Conjugates In Dairy Cattle Urine Sorptive Stir Bar Extraction And Gas Chromatography-Mass Spectometry, S.M. Istiak Ahmed

Masters Theses & Specialist Projects

The global concern regarding the presence of compounds with estrogenic properties in the environment has grown significantly. Endocrine-disrupting compounds (EDCs) are environmental pollutants that disrupt the endocrine systems of both wildlife and humans. Estrogens, with their potent estrogenic effects, are particularly noteworthy among the various substances with endocrine-disrupting properties. They are of concern due to their prevalence in the environment, especially due to dairy waste contamination. These lipophilic compounds can accumulate in livestock fat tissues, potentially entering the human food chain. Sulfated forms of estrone and β- estriol, which exhibit a higher degree of saturation than their non-conjugated counterparts, have …

Electrodeposition Studies Of Gold Nanoparticles And Alginate Hydrogel Films., Harikrishnan Nambiathan Nambiar

Electronic Theses and Dissertations

This dissertation investigates the electrochemical deposition (ECD) and electrophoretic deposition (EPD) processes involving citrate (cit)-stabilized Au nanoparticles (NPs) and calcium alginate (Ca-Alg-Au NP) hydrogel films. The first part of the dissertation investigates the influence of NP size, surface area (SA) coverage, and ligand stabilizers on the electrochemical growth of Au on Au NPs, aiming to enhance our understanding of the growth process during the nucleation and growth of metal NPs. The growth kinetics depend on Au NP size (4 nm > 15 nm > 50 nm) for a constant SA coverage, as determined by the overpotentials for ECD. The growth rate increases …

The Room Temperature Electrolysis Of F-Elements In Aqueous And Ionic Liquid Media: Synthesis, Dissolution, And Reduction, Phillip George Hammer

UNLV Theses, Dissertations, Professional Papers, and Capstones

Procuring F-element metals is no simple task and often requires the use of caustic and hazardous materials at high temperatures. These materials are invaluable for a variety of scientific missions ranging from the elucidation of fundamental properties, as fast spectrum nuclear fuel forms, to pit production modernizing our nuclear stockpiles. Metallic actinide materials are essential to strategic and critical materials recovery, the nuclear energy sector, and weapons production. Room temperature electrolysis is envisioned as a process to recover laboratory scale (milligram to gram) quantities of actinide metals. This process closes the uranium chemical loop allowing the reclamation of materials for …

Studies On Electrochemical Hydrogen Isotope Separation, Liyanage Mayura Sankalpa Silva

All Dissertations

Graphene-integrated Proton Exchange Membrane (PEM) electrochemical cells have emerged as a novel area of scientific investigation in the realm of hydrogen isotope separation. Chemical Vapor Deposited (CVD) graphene has been especially useful due to its large-scale production capability for scaling-up purposes. The research described in this dissertation explores the role that inadvertent introduction of cations, notably ammonium and copper, during the CVD graphene transfer onto PEM substrates, such as Nafion, might play in affecting hydrogen ion transport and isotope separation in PEM electrochemical cells. An extensive review of existing literature exposed a gap concerning unintentional cation introductions during graphene transfer, …

The Influence Of Ion-Ion Correlations On Conductivity In Concentrated Ionic Systems, Md Dipu Ahmed

Masters Theses

This study delves into the fascinating realm of concentrated ionic systems, such as ionic liquids, superionic materials, organic ionic plastic crystals, and polyelectrolytes, which hold immense potential for energy storage applications. The focus is on understanding the intricate role of ionic correlations in shaping their ionic conductivity behavior. These correlations can either boost or impede conductivity, yet their underlying mechanisms remain elusive. Through extensive investigation of various materials, including ionic liquids with differing anionic masses, pure organic ionic plastic crystals, and doped systems, this research employs advanced techniques like dielectric spectroscopy and innovative momentum conservation models to quantify these correlations. …

Binding Interactions Of Biologically Relevant Molecules Studied Using Surface-Modified And Nanostructured Surfaces, Palak Sondhi

Dissertations

This research focuses on the field of surface nanobioscience, wherein different nanosurfaces that will be used as working electrodes in the electrochemical cell are manufactured and surface modified to understand the critical binding interactions between biologically significant molecules like proteins, carbohydrates, small drug molecules, and glycoproteins. This research is essential if we are to determine whether a synthetic molecule can serve as a therapeutic candidate or diagnose a disease in its early stages. In order to fully understand the binding interactions, the study begins with defining some of the fundamental concepts, principles, and analytical tools for biosensing.

Afterwards, we addressed …

Evaluation Of Iron Element By New Cpe Method And (Icp-Ms) In The Wastewater Of The Lifting And Treatment Stations, Mohammed Nasser Hussain, Ahmed Fadhil Khudhair, Hussain Jawad Ahmed

Al-Bahir Journal for Engineering and Pure Sciences

A new micell-mediated phase separation technique has been created to preconcentrate levels of iron before measuring it using a UV-Vis spectrophotometer. The method is based on the extraction of iron from the 1-Nitroso-2- naphthol reagent using Triton X-114 in a cloud point extraction procedure, where the method's ideal conditions were attained. 0.2 mL of Triton X-114, 2.887 mmol. L-1 of 1-Nitroso-2-naphthol reagent, pH = 8, 60 ºC. The Iron detection limit for the method is 0.05 µg. mL-1, and the RSD% is 4.728 µg. mL-1. Linearity was maintained in the iron concentration range of 0.25 to 16 µg. mL-1. Furthermore, …