Physical Sciences and Mathematics Commons^™

Analysis Of Primary Stripper Foils At The Spallation Neutron Source By An Electron Beam Foil Test Stand, Eric Paul Barrowclough

Doctoral Dissertations

Diamond films are used at the Spallation Neutron Source (SNS) as the primary charge exchange foils (i.e., stripper foils) of the accelerated 1 GeV (Gigaelectron volts) hydride ions. The most common type of film used is a nanocrystalline diamond film, typically 17 mm x 45 mm (millimeter) with an aerial density of 350 μg/cm² (microgram per square centimeter). The diamond film is deposited on a corrugated silicon substrate using plasma-assisted chemical vapor deposition. After the growth of the diamond film, 30 mm of the silicon substrate is etched away, leaving a freestanding diamond foil with a silicon handle that …

Characterization Of Highly Heterogeneous Heparin-Protein Complexes Using Novel Mass Spectrometry-Based Approaches, Yunlong Zhao

Doctoral Dissertations

Heparin-like glycosaminoglycan (GAG) is a family of polysaccharide involved in variety of physiological processes. They have potentials to interact with a broad range of proteins and many of them hold crucial values in regulation of protein functions. My dissertation addresses the significance and challenges in the field of heparin-mediated studies, with a focus on the questions in biological and analytical aspects, which are largely hindered by the structural heterogeneity and function diversity of heparin. My dissertation reports the efforts I made in the past few years with respect to the development of novel analytical strategies based on a combination of …

New Optical And Electrochemical Probes For Trace Chemicals With Health And Environmental Impacts, Thomas Stewart Carpenter

Doctoral Dissertations

The work in this dissertation focuses on the development of probes for the analysis of trace chemicals in samples with health and environmental impacts. A paper, Cu(copper)-based colorimetric probe was developed for the detection of toxic hydrogen sulfide (H₂S) gas. A modified Kipp’s apparatus was used to generate desired concentrations of H₂S in a total volume of 1.35 L (liters). The probe shows a qualitative response down to 60 ppb (parts per billion), indicating its ability to be used in industrial settings as a replacement for the commonly used lead acetate strips. When used in conjunction …

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. …

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 …

New Mass Spectrometric Methods For Studying Proteins In Solution And In The Gas Phase, Zhe Zhang

Doctoral Dissertations

This dissertation focuses on the mass spectrometric based methods for studying protein structures in solution phase and in gas phase. Protein structure is important to study because it is related to many disease mechanism and related therapies. The relationship between protein structures in solution phase and in gas phase has been investigated. Especially, the electrostatic interaction is characterized by mass spectrometry (MS). A HDX method has been developed to study protein oligomer kinetics and applied to study β-2-microglobulin (β2m) oligomerization. This dissertation firstly focuses on the relationship between protein gas phase structure and solution phase structure. We studied the structures …

Analysis Of Gold Nanoparticles And Their Use With Laser Desorption/Ionization Mass Spectrometry, Alyssa Marsico

Doctoral Dissertations

Gold nanoparticles (AuNPs) have many unique properties that make them attractive for use in various biological applications. Laser desorption/ionization mass spectrometry (LDI-MS) has been used to monitor AuNPs in complex biological samples but there are still many ways in which AuNPs can be used with MS. In this dissertation, the use of AuNPs to assist in analyte ionization has been investigated. Their ability to enhance signal from biomolecules based on their surface chemistry, size, aggregation and method of deposition has been studied. The first use of an inkjet printer to create surfaces from which analytes can be sampled is discussed …

Gold Nanoparticle Biodistributions And Stability In Vivo From Mass Spectrometric Imaging, Sukru Gokhan Elci

Doctoral Dissertations

Their smaller size, inherent non-toxicity and tunable properties of gold nanoparticles (AuNPs) attract researchers for their use in biological applications such as drug delivery, imaging and therapeutics. Understanding the in vivo fate of these AuNPs are essential for their potential effects in both the environment and the body. In this dissertation, mass spectrometric imaging methods using laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) and laser desorption/ionization (LDI-MS) have been investigated to monitor the in vivo fate of AuNPs. AuNP injected mouse tissue samples can be obtained and readily imaged to track the injected AuNPs using these methods. A first-ever imaging …

Rapid Quantification Of Trypsin Inhibitors In Food And Feed Formulations With Electrospray Ionization Mass Spectrometry, Radheshyam Panta

Doctoral Dissertations

"Presence of anti- nutrients deteriorate the nutritional value of animal foods and feed formulations. The important one being trypsin inhibitors. Trypsin inhibitors in food and feed formulations lower the protein supplement and hence the ultimate consequence is the decrease in growth and development of animals. It is therefore, crucial to monitor trypsin inhibitors in animal food and feed formulations. Research work mentioned in this dissertation is based on the development of rapid, more accurate and robust method for determination of trypsin inhibitor in food and feed formulations. The developed method includes extraction of trypsin inhibitor from food and feed formulation …

Biomarker Discovery Using Urinary Metabolomics For Noninvasive Early Cancer Detection, Casey Franklin Burton

Doctoral Dissertations

"The development of new screening methods for the early detection of cancer remains one of the foremost challenges facing modern cancer research. The emergence of new analytical technologies and their application to 'omics'-based approaches has provided researchers with powerful new tools for molecular biomarker discovery that may benefit early screening of cancer. This dissertation outlines several key advances made toward the application of urinary metabolomics to cancer biomarker discovery. The term urinary metabolomics here refers to the investigation of small metabolites in urine as potential disease biomarkers. The advantage of using this approach lies in its noninvasive sampling characteristics and …

Drinking Water Disinfection By-Products Detection, Formation And The Precursors Removal Study, Runmiao Xue

Doctoral Dissertations

"Haloacetic acids (HAAs) and trihalomethanes (THMs) are two groups of commonly found disinfection by-products (DBPs). Iodinated THMs and HAAs were observed after disinfection of water containing high level of iodide and are proved to be more toxic than their corresponding chlorinated and brominated species. In the presented dissertation, a novel rapid and sensitive high performance ion chromatography-tandem mass spectrometry (HPIC-MS/MS) method has been developed for simultaneous analysis of all these HAAs, bromate, bromide, iodide, and iodate, seventeen compounds in total, without any tedious sample preparation. Besides an efficient analytical method for the detection of DBPs, seeking for a green disinfectant …