Analytical Chemistry Commons^™

Computational Models That Exploit Spatial, Temporal, And Voltage-Current Relationships In The Electrochemical Generation-Collection Of Redox-Active Molecules, Miguel Angel Abrego Tello

Graduate Theses and Dissertations

The numerical studies in this dissertation explore the application of redox cycling, an advanced electrochemical technique, for analyzing bioelectrochemical systems with a particular focus on small-volume samples and involves electrodes that can be activated to oxidize and reduce, separated by varying distances and featuring different geometries. The redox cycling approach facilitates the spatio-temporal interrogation of kinetics, mass transport, and the quantification and identification of chemical systems. We optimize a previously fabricated neural probe design on an SU-8 substrate, featuring coplanar arrays of nine microband electrodes suited for in vivo applications. Through comprehensive in situ and in silico redox cycling studies …

High-Resolution Ion Mobility Analysis Of Isomeric Bile Acids Using Structures For Lossless Ion Manipulations (Slim) Im-Ms, Emmaleigh D. Efird

All Theses

Bile acids are an essential part of the human digestion system and play an important role in lipid absorption, bacteria movement in the small intestine, and regulation of the farnesoid X receptor (FXR) and G protein-coupled bile acid receptors (GPBAR) responsible for homeostasis. They are synthesized in the liver, stored in the gallbladder and the excess is carried on to the small intestine. Many liver and intestinal diseases are diagnosed based on bile acid metabolism pathways and the structures of those bile acids. Therefore, the bile acid structure determines the function of the molecule. Many bile acids are similar in …

Development Of A Flow Cytometry Method For The Identification And Enumeration Of Enterococcus Faecalis, Riza Magbitang

Master's Theses

A multi-color flow cytometry method coupled with fluorescent staining was developed to detect and quantify E. faecalis concentrations in coastal waters as an alternative to the traditional membrane filtration method. The developed method was used to characterize E. faecalis during batch growth and yielded consistent results across the various physiological states of the cells. Additionally, the application of propidium iodide (i.e., a viability stain), afforded the method the ability to differentiate between cells with intact and compromised cell membranes, which raises the potential of quantifying cells that are in viable-but-non-culturable (VBNC) state. Initial field test using natural seawater samples spiked …

First Announcement Of 76th Annual Meeting Of The International Society Of Electrochemistry, International Society Of Electrochemistry (Ise)

Journal of Electrochemistry

No abstract provided.

Tribocorrosion And Metal Release From Austenitic Stainless Steels 304 And 201 In Simulated Cassava Food Contact, Robert Addai, Temitope E. Olowoyo, Thalia E. Standish, Jeffrey Daniel Henderson, Ubong Eduok, Yolanda Hedberg

Chemistry Publications

Cassava is the third most significant calorie source in the tropics. Its processing has changed from traditional methods to stainless steel processing machines. This study investigated the influence of cassava on metal release from two common stainless steels, ASTM 304 and 201, with and without friction, and on tribocorrosion (multianalytically) of 304. Cassava was relatively corrosive and hindered repassivation of the surface oxide of stainless steel, but it also acted as a lubricant against mechanical friction. The combined action of friction and cassava caused a significant increase in iron, chromium, nickel, and manganese release from the stainless steels (30–35- fold …

Establishment Of Protocols To Measure Near-Ir(Nir) Surface-Enhanced Raman Scattering (Sers) Signals Of Nir Dye, Justin B. Ramsey

Forensic Science Master's Projects

Biomedical imaging techniques are crucial for early disease diagnostics, particularly for life-threatening conditions. However, traditional methods have inherent limitations, such as restricted spatial resolution and potential risks associated with repeated exposure to ionizing radiation. Near-infrared (NIR) surface-enhanced Raman spectroscopy (SERS) presents a promising alternative due to its minimal risks and potential for high-resolution biomedical imaging. A key challenge in NIR-SERS biomedical imaging is the development of biocompatible, nontoxic SERS substrates that can be safely introduced into the human body, targeting specific cells and tissues effectively.

NIR-SERS substrates typically consist of gold nanoparticles (AuNPs) modified with biorecognition elements and reporter molecules, …

The Analysis Of Artificially Flavored Coffees, Hannah Knights

Longwood Senior Thesis Proposal

This project aims to determine the molecular components that give artificially flavored coffees their advertised flavor. Much work has been conducted to determine various characteristics such as antioxidant properties, phenolic compounds, flavors, and aromas found in natural coffees. In addition, there is ample literature on the results of sensory tests for a variety of commercial coffees. However, not much work has been conducted to determine the compounds found in artificially flavored coffees that give rise to their distinctive aroma and flavor. This is, perhaps, due to the proprietary nature of the flavoring process employed by commercial producers. The goal of …

Effects Of The Biochar Of Senna Tora On The Soil Fertility Of Misau Farmlands, Bauchi State, Northern Nigeria, Ozoilo Onyeka Calistus, Umar Faruk Hassan, Auwal Adamu Mahmoud, Haruna Baba, Hamza Badamasi, Hannatu Akanang

Journal of Bioresource Management

The use of biochar as an amendment to the soil is attracting the scientific community's attention because of its cost-effectiveness, eco-friendliness, and its promising success in increasing the fertility of the soil and crop yield. In the present study, the effects of biochar from Senna tora applications on soil characteristics and the availability of micronutrients in Misau, Bauchi State, Nigeria, were explored. A completely randomized approach was adopted and duplicated three times, with reference soil (no biochar), 30-day, and 60-day biochar treatments. The biochar was removed at the end of the treatment, and soil samples from the various treatments were …

In Situ Diffuse Reflectance Spectroelectrochemistry Of Cathode Materials In Lithium-Ion Batteries, Lu-Lu Chen, Hao-Ran Li, Wei-Yi Liu, Wei Wang

Journal of Electrochemistry

Developing in situ spectroelectrochemistry methods, which can provide detailed information about species transformation during electrochemical reactions, is very important for studying electrode reaction mechanisms and improving battery performance. Studying real-time changes in the surface of electrode materials during normal operation can be an effective way to assess and optimize the practical performance of electrode materials, thus, in situ and in operando characterization techniques are particularly important. However, batteries are hard to be studied by in situ characterization measurements due to their hermetically sealed shells, and there is still much room for battery characterizations. In this work, a specially designed battery …

Electrochemical Detection Of Glucose Using A Prussian Blue Modified Electrodes Combined With Glucose Encapsulated Within A Xerogel, Daniel Baker, Sarah Davis, Drew Budner

Journal of the South Carolina Academy of Science

Recent literature reports examples of electrochemical biosensor systems that have been developed based upon on the encapsulation of enzymes and metal nanoparticles into a xerogel. These systems have been utilized for the detection of biologically important compounds, such as glucose. These reports on these systems have found acceptable detection limits and linear ranges. At the same time, Prussian blue modified electrodes have been shown to have better operating parameters than metal electrodes for the detection of hydrogen peroxide. In this work, a biosensor system is described that incorporates the encapsulation of glucose oxidize within a xerogel combined with electrochemical detection …

Implementing 1.5 Millimeter Internal Diameter Columns And A Portable Capillary Column Instrument Into Monoclonal Antibody Analytical Workflows, Benjamin Libert

Theses and Dissertations

Using 1.5 mm inner diameter (i.d.) columns to bridge the gap between routinely used 2.1 mm i.d. columns and capillary bore columns allows for a sequential but significant increase in performance without the need for specialized equipment associated with very low dispersion liquid chromatography (LC) systems. These 1.5 mm i.d. columns balance an increase in sensitivity compared to 2.1 mm i.d. columns (theoretically doubling the time-domain peak area in mass sensitive detectors for the same mass load), while mitigating the efficiency losses due to extra-column dispersion effects that are commonly observed with 1.0 mm i.d. columns. Here, the use of …

Turning Trash Into Treasure: Using Old Optical Spectrometers As Learning Tools In Instrumental Analysis, Ken Overway

Chemistry Faculty Scholarship

Chemical instrumentation is complex and expensive. When an instrument becomes nonfunctional, its pedagogical value remains despite its inability to make measurements. This work presents a laboratory experiment which gives new purpose to old optical spectrometers while building knowledge and confidence of students in their understanding of chemical instrumentation. Students are given a guided tour of spectroscopic instruments, starting from the simplest, and are asked to identify components and draw the optical path of each instrument. Allowing students to look inside of decommissioned instruments gives students a chance to see the differences and similarities of optical spectrometers while reinforcing the form …

Heavy Metals Implications To Sediment Microbiome And Coral Response To Arsenic Dosing, Dimitrios G. Giarikos, Amy Hirons, Jose V. Lopez, Abigail Renegar, Jason Gershman

SECLER Data

No abstract provided.

Production Of The Siderophore Lysochelin In Rich Media Through Maltose-Promoted High-Density Growth Of Lysobacter Sp. 3655, Fang Zhang, Jia Liu, Lin Jiang, Yongbiao Zheng, Lingjun Yu, Liangcheng Du

Department of Chemistry: Faculty Publications

Siderophores are produced by bacteria in iron-restricted conditions. However, we found maltose could induce the biosynthesis of the siderophore lysochelin in Lysobacter sp. 3655 in rich media that are not compatible with siderophore production. Maltose markedly promoted cell growth, with over 300% increase in cell density (OD₆₀₀) when LB medium was added with maltose (LBM). While lysochelin was not detectable when OD₆₀₀ in LBM was below 5.0, the siderophore was clearly produced when OD₆₀₀ reached 7.5 and dramatically increased when OD₆₀₀ was 15.0. Coincidently, the transcription of lysochelin biosynthesis genes was remarkably enhanced following the …

Hatt-Flow: Hierarchical Attention-Flow Mechanism For Group-Activity Scene Graph Generation In Videos, Naga Venkata Sai Raviteja Chappa, Pha Nguyen, Thi Hoang Ngan Le, Page Daniel Dobbs, Khoa Luu

Electrical Engineering and Computer Science Faculty Publications and Presentations

Group-activity scene graph (GASG) generation is a challenging task in computer vision, aiming to anticipate and describe relationships between subjects and objects in video sequences. Traditional video scene graph generation (VidSGG) methods focus on retrospective analysis, limiting their predictive capabilities. To enrich the scene-understanding capabilities, we introduced a GASG dataset extending the JRDB dataset with nuanced annotations involving appearance, interaction, position, relationship, and situation attributes. This work also introduces an innovative approach, a Hierarchical Attention–Flow (HAtt-Flow) mechanism, rooted in flow network theory to enhance GASG performance. Flow–attention incorporates flow conservation principles, fostering competition …

Molecular-Level Studies Of Nanopatterned Biomolecules With Atomic Force Microscopy, Ashley R. Walker

LSU Doctoral Dissertations

Atomic force microscopy (AFM) is an analytical technique in which a tipped probe is gently scanned across the surface in a raster pattern to generate digital images of a sample at the nanoscale. The AFM instrument has three general operational modes, which are contact, non-contact and tapping-mode, that can be used to examine materials at the atomic level. Single-molecular details of biological molecules and other soft organic materials can be captured with minimal denaturation in either ambient or liquid environments when using tapping-mode AFM. In tapping-mode, the probe is driven to oscillate vertically while the tip is scanned across the …

Non-Destructive Determination Of Surface Area In Reverse Phase Chromatographic Columns, Margaret Figus

Seton Hall University Dissertations and Theses (ETDs)

Excess adsorption isotherms of acetonitrile and methanol from water were measured on eight commercial columns. Columns used in this study represent the latest examples in column development and include three different poroshell columns (Kinotex C18, Ascentis C18, and Halo C18) as well as conventional columns with significantly different adsorbent geometries (Allure C18, YMC C18) and various hybrid-silica columns (Gemini C18, Xterra C18, and XBridge C18). Comparison of the excess adsorption isotherms measured on all these columns and expressed in surface-specific form demonstrated significant similarity of the adsorption properties of all columns, which allows the introduction of the Standard Excess Adsorption …

The Investigation Of The Reaction Of 2,3-Dimethylfuran With O(³P) And The Estimate Of The Photoionization Cross Section Of C-Cl And Absolute Photoionization Cross Sections Of Chlorinated Organic Compounds, Yilan Lori Chen

Master's Theses

The work presented in this thesis focuses on gas-phase reactions, which are fundamental for reducing greenhouse gas emissions and mitigating climate change. The experiments are performed at the Advanced Light Source (ALS) of Lawrence Berkeley National Laboratory, where there is a time-of-flight mass spectrometer coupled with tunable synchrotron radiation at Beamline 9.0.2 to collect high-quality data.

Chapter 1 details the background and purpose of each project, along with an overview of the origins of synchrotron radiation and time-of-flight mass spectrometry. The adaptation of biofuels is a way to minimize carbon emission and air pollutants, so research surrounding the reaction dynamics …

Advancing Simultaneous Extraction And Sequential Single-Particle Icp-Ms Analysis For Metallic Nanoparticle Mixtures In Plant Tissues, Lei Xu, Xingmao Ma, John Yang, Joel G. Burken, Paul Ki-Souk Nam, Honglan Shi, Hu Yang

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Engineered Nanoparticles (ENPs) Have Been Increasingly Used in Agricultural Operations, leading to an Urgent Need for Robust Methods to Analyze Co-Occurring ENPs in Plant Tissues. in Response, This Study Advanced the Simultaneous Extraction of Coexisting Silver, Cerium Oxide, and Copper Oxide ENPs in Lettuce Shoots and Roots using Macerozyme R-10 and Analyzed Them by Single-Particle Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Additionally, the Standard Stock Suspensions of the ENPs Were Stabilized with Citrate, and the Long-Term Stability (Up to 5 Months) Was Examined for the First Time. the Method Performance Results Displayed Satisfactory Accuracies and Precisions and Achieved Low Particle Concentration …

Model To Demonstrate Effects Of Mass Transfer And Applied Current In An Electrolytic Cell, George Ankrah

Reviews, Analyses, and Instructional Studies in Electrochemistry (RAISE)

This study investigates the relationship between applied current and resulting cell potential in an electrolytic system, considering the transport of electroactive species. By applying Michael Faraday's laws of electrolysis and the Nernst-Planck equation, the behavior of electroactive species in diffusion-controlled systems with and without stirring is modeled. The plots demonstrate how stirring enhances ion transport and establishes a stable Nernst diffusion layer, affecting the kinetics of electrochemical reactions. Understanding these dynamics is crucial for optimizing electrolysis processes.