Dissertations / Theses: 'Analytical chemistry|Engineering'

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Blanchard, Thomas W. "Design and Construction of an Atmospheric Pressure Imploding Thin-Film Theta Pinch Device as an Atomization Source for Atomic Emission Spectroscopy." Thesis, Southern Illinois University at Edwardsville, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=1606629.

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A direct solid sampling device has been developed using a theta pinch configuration to generate a pulsed plasma at atmospheric pressure. Energy from a 20kV, 1.80µF capacitive discharge system is to inductively couple with the sacrificial aluminum thin film and produce a cylindrical plasma. Electrical simulations of the main discharge circuit were analyzed to determine the necessary circuit components that would withstand the worst case scenario. The design uses 4” by 0.75” copper stock at varying lengths to make the transmission lines and must also accommodate a spark gap switch and Rowgowski coil into the design. The 5.5 turn prototype coil design is used in initial testing to examine behavior of the system when discharged.

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Garcia, Juan Fernandez. "Ion Mobility-Mass Spectrometry Measurements and Modeling of the Electrical Mobilities of Charged Nanodrops in Gases| Relation between Electrical Mobility, Size, and Charge, and Effect of Ion-Induced Dipole Interactions." Thesis, Yale University, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=3663632.

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Over recent years, Ion Mobility–Mass Spectrometry (IMS–MS) measurements have become a widely used tool in a number of disciplines of scientific relevance, including, in particular, the structural characterization of mass-selected biomolecules such as proteins, peptides, or lipids, brought into the gas-phase using a variety of ionization methods. In these structural studies, the measured electrical mobilities are customarily interpreted in terms of a collision cross-section, based on the classic kinetic theory of ion mobility. For ideal ions interacting as smooth, rigid-elastic hard-spheres with also-spherical gas molecules, this collision cross-section (CCS) is identical to the true, geometric cross section. On the other hand, for real ions with non-perfectly spherical geometries and atomically-rough surfaces, subject to long-range interactions with the gas molecules, the expression for the CCS can become fairly intricate.

This complexity has frequently led to the use of helium as the drift gas of choice for structural studies, given its small size and mass, its low polarizability (minimizing long-range interactions), and its sphericity and lack of internal degrees of freedom, all of which contribute to reduce departures between measured and true cross-sections. Recently, however, a growing interest has arisen for using moderately-polarizable gases such as air, nitrogen, or carbon dioxide (among others) in these structural studies, due to a number of advantages they present over helium, including their higher breakdown voltages (allowing for higher instrument resolutions) and better pumping characteristics. This shift has, nevertheless, remained objectionable in the eye of those seeking to infer accurate structural information from ion mobility measurements and, accordingly, there is a critical need to study whether or not measurements carried out in such gases may be corrected for the finite size of the gas molecules and their long-range interactions with the ions, in order to provide cross-sections truly representative of ion geometry. A first step to address this matter is undertaken here for the special case of nearly-spherical, nanometer-sized ions.

In order to attain this goal, we have performed careful and accurate IMS–MS measurements of hundreds of electrospray-generated nanodrops of the ionic liquid (IL) 1-ethyl-3-methylimidazolium tetrafluoroborate (EMI-BF₄), in a variety of drift gases (air, CO₂, and argon), covering a wide range of temperatures (20-100 °C, for both air and CO₂), and considering nanodrops of both positive and negative polarity (the latter in room-temperature air only). Thanks to the combined measurement of the mass and mobility of these nanodrops, we are able to simultaneously determine a mobility-based collision cross-section and a mass-based diameter (taking into account the finite compressibility of the IL matter) for each of them, which then allows us to establish a comparison between the two.

Over the entire range of experimental conditions investigated, our measurements show that the electrical mobilities of these nearly-spherical, multiply-charged IL nanodrops are accurately described by an adapted version of the well-known Stokes—Millikan (SM) law for the mobility of spherical ions, with the nanodrop diameter augmented by an effective gas-molecule collision diameter, and including a correction factor to account for the effect of ion—induced dipole (polarization) interactions, which result in the mobility decreasing linearly with the ratio between the polarization and thermal energies of the ion–neutral system at contact. The availability of this empirically-validated relation enables us, in turn, to determine true, geometric cross-sections for globular ions from IMS—MS measurements performed in gases other than helium, including molecular or atomic gases with moderate polarizabilities. In addition, the observed dependence of the experimentally-determined values for the effective gas-molecule collision diameter and the parameters involved in the polarization correction on drift-gas nature, temperature, and nanodrop polarity, is further evaluated in the light of the results of numerical calculations of the electrical mobilities, in the free-molecule regime, of spherical ions subject to different types of scattering with the gas molecules and interacting with the latter under an ion–induced dipole potential. Among the number of findings derived from this analysis, a particularly notable one is that nanodrop–neutral scattering seems to be of a diffuse (cf. elastic and specular) character in all the scenarios investigated, including the case of the monatomic argon, which therefore suggests that the atomic-level surface roughness of our nanodrops and/or the proximity between their internal degrees of freedom, rather than the sphericity (or lack of it) and the absence (or presence) of internal degrees of freedom in the gas molecules, are what chiefly determine the nature of the scattering process.

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Murphy, Craig E. "Alkaline hydrogen peroxide bleaching : a study of the evolved gases." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=38250.

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The principle objectives of this thesis are to determine which gases are evolved during alkaline hydrogen peroxide bleaching, and to develop techniques to measure these gases. Also, the relationship of the composition of the evolved gases from alkaline hydrogen peroxide bleaching of mechanical pulp to the reaction kinetics was elucidated. We have shown that the only gas being evolved into the bleaching headspace is oxygen; whereas, carbon dioxide is produced and fixed in solution as carbonate.
A new non-invasive technique for measuring the amount of oxygen evolved throughout the bleaching reaction was developed. This technique is able to be used in laboratory bleaching experiments that simulated most industrial parameters except consistency, which is limited to hand mixing at medium (10--12%) consistencies. With this method, we have shown that pulp washing, caustic charge and addition of chelating agent play key roles in the rates of oxygen evolution due to the decomposition of hydrogen peroxide. Better washing and higher chelating agent additions result in significant lowering of the rates of oxygen evolution. The rate of decomposition has been related to the dissociation of hydrogen peroxide which is dependent on pH.
The effect of transition metal ions on the kinetics of hydrogen peroxide decomposition during alkaline hydrogen peroxide bleaching of mechanical pulps was investigated. Iron, whether added or native to the pulp, did not contribute to the decomposition of hydrogen peroxide in the presence of lignin. Manganese is the main catalyst for peroxide decomposition, whether added or native to the pulp. The initial rate of oxygen evolution, in the presence of manganese, varies linearly with manganese concentration. Although alkali itself does decompose hydrogen peroxide, increased caustic charge results in an increase in the manganese induced decomposition rate. Kinetic equations are presented, which account for manganese concentration and caustic charge. The effect of DTPA on reducing the rate of hydrogen peroxide decomposition has been attributed to the chelation of manganese.
The relationship between hydrogen peroxide decomposition and the oxidation state of iron and manganese was determined visually. The effect of other bleaching additives on the catalyzed decomposition of hydrogen peroxide were also evaluated. Manganese is unreactive in the +II state, yet very reactive in the +III and +IV forms. Iron is not reactive in the presence of lignin. The presence of cellulose acts to prevent the formation of large low surface area precipitates of manganese III and IV. Manganese IV is the most likely reactive species in alkaline hydrogen peroxide bleaching. DTPA will bind Mn(II) but not the other oxidation states. The DTPA-manganese complex once formed is stable even after the pH is increased.
A new technique for the determination of carbon dioxide produced during hydrogen peroxide bleaching is presented. Carbon dioxide is produced during alkaline hydrogen peroxide bleaching, from reactions of hydrogen peroxide and lignin. The rate of carbon dioxide evolution varies linearly with lignin concentration. Kinetic equations are presented and rate constants have been calculated. The source of carbon dioxide is most likely decarboxylation of carboxylic acid groups formed in lignin by alkaline hydrogen peroxide oxidation.

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Lafrance, Denis 1965. "Near infrared determination of Lactate in biological fluids and tissues." Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=84866.

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Lactate is a key metabolite of glycolytic activity and as such, can be used as an indicator of the energy production of the whole organism, for the assessment of tissue perfusion and oxidative capacity. Estimating lactate levels in biological fluids allows the determination of anaerobic threshold during physical exercise. Likewise, lactate is of significant importance in several clinical situations, where a rapid and easy method is needed for diagnostic assessment and survival rate increase of the patient.
To achieve this objective, the potential of Near Infrared Spectroscopy (NIRS) to quantify lactate in biological fluids and tissues was evaluated. Initially, the project focused on quantifying of lactate in plasma samples taken from exercising humans. Using Partial Least Squares (PLS) and a leave-N-out cross validation routine, it was found that lactate concentration in human plasma could be estimated with a standard error of cross validation of 0.51 mmol/L.
To minimize sample preparation and reduce the time of analysis, NIRS was then evaluated as a technique for rapid analysis of lactate in whole blood from exercising rats and humans. Furthermore, standard addition method was used to expand the lactate concentration range and therefore cover a greater part of the physiological lactate concentration range. Regression analysis provided standard errors of cross validation of 0.29 mmol/L and 0.65 mmol/L for rats and humans respectively.
To improve precision, referenced lactate measurements were calculated. In this method, baseline spectra of subjects were subtracted from all collected spectra before chemometric routines were used. An improvement of the standard error of cross validation to 0.21 mmol/L was found by applying this procedure.
In vivo measurement of lactate during exercise in humans by NIRS was also evaluated. Using diffuse reflectance and 2D correlation spectroscopy, lactate was identified as the primary constituent monitored by in vivo measurements. Regression analysis resulted in a substantial error of 2.21 mmol/L for absolute measurements. However, results for referenced lactate measurements provided a significant improvement of the standard error of cross validation to 0.76 mmol/L. This finding suggests that NIRS may provide a valuable tool to assess in vivo physiological status for both research and clinical needs.

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Banks, Mark Lavoir 1960. "Detection of decontamination solution chelating agents using ion selective coated-wire electrodes." Thesis, The University of Arizona, 1992. http://hdl.handle.net/10150/278120.

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It is the purpose of this thesis to explore the feasibility of using coated-wire electrodes to measure chelating agent concentration. Chelating agents are often found in radioactive decontamination solutions because they aid in the removal of radionuclides from contaminated surfaces by increasing their solubility. However, this characteristic will also enhance the mobility of the radionuclide and thus its transport out of a waste disposal site. Coated-wire ion selective electrodes, based on a polyvinylchloride membrane using dioctylphthalate as a plasticizer and dinonylnaphthalene-sulfonic acid as a counterion, were constructed for five commonly utilized chelating agents (ethylenediaminetetracetic acid (EDTA), nitrilotriacetic acid (NTA), citric acid, oxalic acid and tartaric acid). The EDTA and NTA electrodes' calibration characteristics exhibited acceptable behavior in pure standard solutions. From data obtained while using the EDTA and NTA electrodes in a cement environment, further research needs to be done in the area of ion interference.

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Sounart, Thomas L. "Electrokinetic transport and fluid motion in microanalytical electrolyte systems." Diss., The University of Arizona, 2001. http://hdl.handle.net/10150/279916.

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Electrically-driven separation schemes, such as zone electrophoresis (ZE), isotachophoresis (ITP) and isoelectric focusing (IEF), are used profoundly to fractionate mixtures of charged compounds for preparative and particularly analytical applications. Inherent to the separation process is the development of local variations in the electrical conductivity, pH, electric field, etc. One-dimensional, quantitative descriptions of the spatio-temporal evolution of these variations, and their role in the separation process, have been developed over the past two decades. These descriptions lend significant insight into the electromigrational behavior of analytes and buffer components. Nevertheless, because they are one-dimensional, such descriptions omit important effects of electrokinetic fluid motion. The fluid motion arises naturally in the context of the separation scheme, and affects the evolving spatial gradients associated with the separation process. One-dimensional simulations have also been plagued by numerical limitations associated with advection-dominant transport in regions of sharp concentration gradients. In this dissertation, the numerical difficulties are resolved, and a general two-dimensional model of electrokinetic separations is presented. Because the balance laws account for coupling of the velocity field to the ion transport, a variety of processes important to both microfluidic manipulations and analytical separations can be considered. High-ionic strength electroosmotic pumping and field-amplified sample stacking are examined in detail. It is demonstrated that unsteady fluid eddies disperse the gradients in the field variables, and this limits the efficacy of microanalysis processes. Scaling arguments suggest that, at least for simple geometries, approximate solutions to the general model are possible. Semi-analytic approximations are constructed for the fluid velocity v and electric field E, and the parameter space over which they apply is defined. These approximations reduce simulation times by about two thirds, and provide general information on the dominant physics in microanalysis processes. The scale analysis and simulation results demonstrate that although cross-sectional conductivity gradients meet or exceed those in the axial direction, the electric field is essentially unidirectional. Also, at sufficiently high electric field strengths (ca. several hundred V/cm), nonlinear electrohydrodynamic stresses begin to influence the fluid motion. Finally, if the electrical stresses are negligible, the semi-analytic solutions for v and E permit 1-D macrotransport representations of the solute transport. Effective 1-D simulations yield cross-sectionally averaged values for the field variables in orders of magnitude less simulation time than 2-D simulations.

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Schoenfisch, Mark Henry 1970. "Electrochemical and spectroscopic characterization of self-assembled monolayers: Electrode modification for cardiac pacing applications." Diss., The University of Arizona, 1997. http://hdl.handle.net/10150/282526.

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New biomaterials for permanent cardiac pacemaking electrode applications based on Au surfaces chemically modified with self-assembled monolayers (SAMs) have been developed. The research described herein focuses on four areas related to understanding the extraordinary pacing exhibited by modified pacemaker electrodes. SAM-modified pacemaker electrodes were fabricated and tested in canines for chronic and acute cardiac pacing. In addition to having electrical properties suitable for pacing the heart, SAM-modified electrodes are proven superior to control electrodes in pacing performance. The data suggest that the biocompatibility of electrically conductive materials can be controlled at the molecular level with monolayer organic surface films. The development of a small rodent model for studying cardiac pacing was explored as an alternative to using canines in clinical studies. Rodents, not previously used for such studies, were demonstrated to be excellent mammals for testing initial electrode modification strategies. Myocardial tissue resistance in a living mammalian heart was determined using chronoamperometry and cyclic voltammetry of Ru(NH3 Pacemaker systems represent complete electrochemical cells. Thus, modified pacemaker electrodes are simply examples of chemically modified electrodes, an area of electrochemistry which has been studied extensively over the past two decades. For these types of systems, the interfacial chemistry occurring in the vicinity of the SAM is crucial to its function. Therefore, investigations into the stability, order, and orientation of SAMs at the metal electrode surface, and solvent behavior at the outer edge of the SAMs were undertaken. Such fundamental information is critical in understanding the biocompatibility of these modified pacemaker electrodes, and potentially, in understanding the mechanism for the pacing efficacy of the electrode modification. Surface Raman spectroscopy using an emersion approach was developed as an exceptional technique for probing the structural order and stability of SAMs on Ag and Au after exposure to solvent, electrolyte, and potential. Finally, the stability of these SAM-modified pacemaker electrodes to air and mechanical stress was investigated. Raman spectroscopy, cyclic voltammetry and x-ray photoelectron spectroscopy were utilized to better understand the shelf-life of modified electrodes.

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Pennebaker, Frank Martin 1970. "High precision and spatial analysis of platinum, palladium, and rhodium in catalytic converters by inductively coupled plasma atomic emission spectroscopy and inductively coupled plasma mass spectrometry." Diss., The University of Arizona, 1998. http://hdl.handle.net/10150/282792.

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The accuracy and precision of catalytic converter analysis using conventional analytical methodology such as fire assay, x-ray fluorescence, atomic absorption and ICP-AES are typically in the range of ±7-10% RSD. Due to the high cost of noble metals, methods of analysis with increased accuracy and precision are desired to evaluate the loading of noble metals onto converter bricks. The investigations described in this work have resulted in a better understanding of many of the inherent problems and have contributed new approaches for sample dissolution and analysis using array detector based Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS). These methods are shown to be accurate and precise for the analysis of Pt, Pd, and Rh in catalytic converters. Catalytic converters are difficult to dissolve by conventional acid methodology. While carius, tubes have previously been employed to dissolve small weights of sample, complete dissolution of increased amounts of sample, as needed for high precision ICP-AES analysis, has been hindered by the insufficient oxidation potential of the acids in the carius tube. In this work, the addition of ferric chloride is shown to increase the dissolving power of the carius tube method and specifically targets Pt, Pd and Rh for dissolution. Simultaneous collection of analyte wavelengths and simultaneous background correction, as performed with multichannel array detector ICP-AES instrumentation, have enhanced sensitivity and precision in catalytic converter analysis when compared to single channel instrumentation. The studies described within this dissertation demonstrate that flicker noise has been effectively eliminated through the use of multichannel array based ICP-AES instrumentation. With proper line selection and the use of the high-resolution system, Pt, Pd and Rh in catalytic converters can be analyzed with precision of 1-1.5%. ICP-AES accuracy has been confirmed through isotope dilution ICP-MS employing new methodology to avoid Zr isobaric interferences.

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Liu, Zhijie. "Reductive dehalogenation of chlorinated aliphatic compounds in electrolytic systems." Diss., The University of Arizona, 1999. http://hdl.handle.net/10150/283929.

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A series of chlorinated low-molecular-weight alkanes and alkenes was transformed electrolytically at metal cathodes at potentials from -0.3 to -1.4V (vs. SHE). Products included nonchlorinated hydrocarbons and less chlorinated intermediates. Product distributions are highly dependent on cathode material and applied cathode potential. Kinetics was first-order in the concentration of the halogenated targets. The specific first-order rate constants are function of cathode potential, cathode material, solution characteristics, and reactant identify. When transformation kinetics was governed by polarization resistance, rate constants were correlated with degree of halogenation and standard reduction potential for the predominant transformation reaction (as indicated by product analysis). Log-transformed reaction rate constants for reduction of chlorinated alkanes, derived via experiments at the same cathode potential (E(c) = -1.0 or -1.2V vs. SHE), were linearly related to carbon-halogen bond dissociation energies. A physical model for the observed correlation was developed from transition-state theory. The chlorinated ethenes reacted much faster than predicted from bond enthalpy calculations, suggesting that alkenes are not transformed via the same mechanism as the chlorinated alkanes. Polarographic study demonstrated that the shift of E₁/₂ of CCl₄ reduction was correlated with water concentration in solvent-predominated mixtures. Successful interpretation of these findings with a physical model suggested that solvents involved the rate-determining step of CCl₄ electrolysis both kinetically and mechanistically. The capture of trichloromethyl radicals with a spin trap (PBN) in an electrochemical system provided direct evidence supporting the free radical mechanism in electrolytic reduction of CCl₄. Gas-phase reductions of chlorinated alkanes and alkenes were studied in a modified fuel cell. Reactor performance was a function of the metal catalyst amended to the reactor cathode, the reactor potential, cathode temperature, the target compound identity, the partial pressure of O₂(g) in the cathode chamber and the condition (time in service) of the cathode. Single-pass CCl₄ conversions could achieve 90 percent with a mean residence time for gases in the porous cathode much less than a second. Reactor performance deteriorated with the presence of oxygen and time in service. Conversion efficiency was restored, however, by temporarily eliminating the halogenated target(s) from the influent stream or by briefly reversing reactor polarity.

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Pusel, Julia M. "Heterogeneous catalysts for hydrogen production from methane and carbon dioxide." Thesis, California State University, Long Beach, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=1585646.

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Several heterogeneous catalysts were studied for synthesis gas production through dry reforming of methane (DRM). This process uses carbon dioxide in lieu of the steam that is traditionally used in conventional methane reforming to produce hydrogen that can then be repurposed in more chemical processes [2]. The monometallic catalysts explored were Ni/Al₂O₃ and Ni/CeZrO₂ followed by their bimetallic versions PtNi/Al₂O₃ and PtNi/CeZrO₂ at 800°C. In addition to these catalysts, platinum supported Zeolitic Imidazolate Framework (ZIF)-8 was also investigated in comparison with PtNi/CeZrO₂ at 490°C. The studies suggest that these catalysts are suitable for promoting the dry reforming of methane for hydrogen production.

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Chen, Jacqueline T. 1973. "A fully automated system for analyzing phosphorus magnetic resonance spectroscopy data obtained from skeletal muscle in vivo /." Thesis, McGill University, 1999. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=30237.

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Phosphorus magnetic resonance spectroscopy (31P-MRS) permits the measurement of high-energy phosphates in the gastrocnemius muscle at rest and during recovery from exercise. This examination is a powerful non-invasive method to evaluate muscle mitochondrial function in vivo. Data analysis, however, can be both time-consuming and user-dependent. I designed a fully-automated system to quantify both resting and recovery spectra, followed by quantification of metabolite recovery kinetics. This included quantifying the recovery kinetics of adenosine diphosphate (ADP), an index of mitochondrial function which previously had not been properly characterized. I modeled the transition from ischemic-exercise to perfused-recovery as a step function, and fitted the ADP recovery with a second-order step-response function. Furthermore, I used nearest-neighbour methods to account for the effects of physical conditioning and metabolic work on the recovery kinetics. This fully-automated method of analyzing 31P-MRS data provides comprehensive results relevant to the diagnosis and monitoring of patients with metabolic myopathies.

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Glavan, Ana. "Chemical Approaches to the Surface Engineering of Paper and Cellulose-Based Materials for Microfluidics, Electronics and Low-Cost Diagnostics." Thesis, Harvard University, 2016. http://nrs.harvard.edu/urn-3:HUL.InstRepos:26718749.

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Paper (and other cellulose-based materials such as cotton thread and fabrics) are underexploited as materials for the construction of “high-tech” and “lab-on-a-chip” devices. One major drawback of paper is its tendency to absorb water from the environment and, with wetting, to change its mechanical properties; other challenges relate to control over the attachment of molecules (e.g. antibodies, DNA) and cells on its surface, and to the addition of electronic function. The goal of this thesis is to develop paper as a substrate for a range of applications— microfluidics, substrates for electronic systems and MEMS, low-cost diagnostics, cell biology, and optics. The approach involves chemically modifying the surface of the paper to provide new functions without altering any of its defining properties: mechanical flexibility, foldability, light weight, gas permeability, and low cost. The first part of my thesis describes the modification of paper by silanization with organosilanes such as alkyl- and fluoroalkyl trichlorosilanes in the gas phase. Here, silanization is used to lower the surface free energy of the paper and to minimize the tendency of paper to absorb liquids and vapors, and especially water. Chapter 1 and Appendix 3 demonstrate that the combination of long fluoroalkyl chains of grafted siloxanes with the micro-scale roughness and porosity of paper yielded a material that is omniphobic (both hydrophobic and oleophobic), while preserving the properties of mechanical flexibility and low resistance to transport of gas of the untreated paper. Appendix 3 shows that features of omniphobic paper can be used to construct microtiter plates and liquid-filled gas sensors using standard paper folding techniques, while Appendix 4 shows that new type of microfluidic device fabricated by carving microchannels into the surface of omniphobic paper. The resulting devices have open, unobstructed channels (with dimensions as small as 45 μm) and thus exhibit fluid dynamics similar to conventional PDMS-based microfluidics, but are much lighter and have the potential to be much less expensive than PDMS-based devices. The second part of my thesis is focused on engineering the surface of paper to enable efficient immobilization of capture and target molecules for bioanalysis. In one approach, described in Appendix 5, we exploit the ease with which the surface chemistry of paper (i.e. the surface of the cellulose fibers making up the paper) can be modified, in order to enhance the immobilization of antibodies and antigens on the surface of the paper via hydrophobic interactions, while preventing the wicking of the fluids into the paper substrate. As an application in low-cost diagnostics, we describe a low-cost electrochemical device for ELISA intended for use in resource-limited settings. In a second approach, described in Chapter 2, we developed of an efficient procedure for assembling microarrays of ssDNA and proteins on paper, at the lowest practical cost. This method starts with the synthesis of DNA oligonucleotides covalently linked to paper, and proceeds to generate ssDNA arrays that, through hybridization with complementary strands of DNA, are capable of simultaneously capturing DNA, DNA-conjugated protein antigens, and DNA-conjugated antibodies. The third part of my thesis describes the simple, inexpensive fabrication of electrodes for paper-based electrochemical systems. A first method describes, in Appendix 6, the development of inkjet printing as a method for high resolution printing of conductive patterns on omniphobic “RF” paper, both to extend its promise as a substrate for paper electronics, and to enable us to integrate it into our program in low-cost, paper based diagnostics. A second method, described in Chapter 3, circumvents the need for printing, and instead focuses on the fabrication and reconfiguration of simple, versatile, and inexpensive electroanalytical devices in which conventional stainless-steel pins—in unmodified form or after coating with a carbon paste—are used as electrodes.
Chemistry and Chemical Biology

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Pearce, E. I. "Analytical techniques for the study of soft contact lens spoilation." Thesis, Aston University, 1991. http://publications.aston.ac.uk/9761/.

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Soft contact lens wear has become a common phenomenon in recent times. The contact lens when placed in the eye rapidly undergoes change. A film of biological material builds up on and in the lens matrix. The long term wear characteristics of the lens ultimately depend on this process. With time distinct structures made up of biological material have been found to build up on the lens. A fuller understanding of this process and how it relates to the lens chemistry could lead to contact lenses that are better tolerated by the eye. The tear film is a complex biological fluid, it is this fluid that bathes the lens during wear. It is reasonable to suppose that it is material derived from this source that accumulates on the lens. To understand this phenomenon it was decided to investigate the make up and conformation of the protein species that are found on and in the lens. As inter individual variations in tear fluid composition have been found it is important to be able to study the proteins on a single lens. Many of the analytical techniques used in bio research are not suitable for this study because of the lack of sensitivity. Work with poly acrylamide electrophoresis showed the possibility of analyzing the proteins extracted from a single lens. The development of a biotin avidin electro-blot and an enzyme linked aniibody electro-blot, lead to the high sensitivity detection and identification of the proteins present. The extraction of proteins from a lens is always incomplete. A method that analyses the proteins in situ would be a great advancement. Fourier transform infra red microscopy was developed to a point where a thin section of a contact lens could yield information about the proteins present and their conformation. The three dimensional structure of the gross macroscopic structures termed white spots was investigated using confocal laser microscopy.

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Vreugdenhil, Andrew J. "Applications of vibrational spectroscopy to inorganic environmental and industrial systems." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=34477.

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Environmental and industrial systems have been investigated using vibrational spectroscopy. These applications were chosen to demonstrate the potential of vibrational spectroscopy as a means of obtaining molecular information from either in-situ or model environments in a rapid, convenient manner requiring minimal sample handling. Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) has been used to investigated two systems in the area of environmental chemistry. Using the characteristic CO stretching bands of the Mn(CO)$ sb3$ fragment, methylcyclopentadienyl manganese tricarbonyl (MMT), an additive to Canadian gasoline, was detected on soils treated with gasoline up to twelve months after exposure. Its longevity on and its interaction with different soils and various substrates was studied. A breakdown of the local symmetry of the manganese tricarbonly moiety suggests a Bronsted-type interaction between the soil and the carbonyl ligands of MMT. The uptake by harbour sediments of two tributyltin species used as marine antifouling agents, was also studied using DRIFTS. Water/sediments ratios and salinity were investigated as factors affecting adsorption. A novel infrared cell for probing the gas-phase infrared spectroscopy (HAGIS) cell was used to study the thermal decomposition products of ethylxanthanate-treated sulphide minerals and those of the related ethylxanthate metal complexes. The gas-phase decomposition products from sulphide minerals treated with ethylxante include $ rm CS sb2, COS, CO sb2, CH sb4, SO sb2,$ ethanol and possibly metal xanthates. The relative amounts of the products depend on the type of mineral surface, the temperature and the atmosphere in the cell. Iron, zinc, lead, nickel and copper ethylxanthate complexes were synthesized, and their thermal decomposition products were also studied by HAGIS. The complexes were classified according to the generation of the primary gas-phase decomposition products. Schemes for the produ

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Stork, Kurt Forrest 1961. "Surface chemistries of oxygen and water on titanium-iron bimetallic systems." Thesis, The University of Arizona, 1990. http://hdl.handle.net/10150/277327.

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The dissociative chemisorption of oxygen and water on Fe, Ti, and adlayers of each metal on the other have been explored via surface electron spectroscopies. Auger Electron Spectroscopy (AES) and X-ray Photoelectron Spectroscopy (XPS) have been used to monitor the reactions of titanium and iron with low exposures (from one to several hundred langmuirs) of oxygen and/or water vapor. Comparisons and contrasts are drawn between bulk metals and adlayer alloys--alloys formed by vapor depositing a few angstroms of one metal on top of a relatively thick film of the other metal. Most notable is the ability of a very thin layer of titanium to lessen the reactivity of a thick iron film toward oxygen.

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Zangmiester, Rebecca Anne. "Octasubstituted phthalocyanine assemblies: Characterization, polymerization, and patterning." Diss., The University of Arizona, 2001. http://hdl.handle.net/10150/279830.

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This dissertation explores the characterization of new phthalocyanine materials, and the processability of these materials with regard to thin film structures envisioned for use in organic based electronic devices. Highly ordered, coherent molecular assemblies are formed by Cu centered benzyloxyethoxy-substituted phthalocyanines. The influence of molecular aggregate interactions with solid supports, based on phenyl-phenyl interactions, manifests itself in large changes in wettability, and also in molecular orientations within those molecular aggregates. Selective deposition of these Pc assemblies was achieved based on chemical interactions with a heterogeneous surface. A facile process of creating alternating hydrophobic/hydrophilic regions on a Au substrate surface through a combination of microcontact printing and electropolymerization techniques (μCP/EP) was demonstrated. Optimization of the hydrophobic channel bottom regions with a phenyl terminated dopant results in patterned phthalocyanine stripes up to 500 μm in length. The substitution of a Co metal center does not appreciably influence the properties of the benzyloxyethoxy-substituted phthalocyanine material, although the lone pair electron, in the d(z)² orbital perpendicular to the Pc macrocycle, appears to be responsible for differences in molecular orientation. The ability of the Co metal to coordinate ligands (i.e. O₂) is particularly evident in electrochemical data taken of this material. Two new photoreactive phthalocyanines, with styryl- and cinnamyl-terminations, result in the formation of new materials, whose preliminary characterization is presented. The photoexcited polymerization of the styryl-substituted material resulted in formation of a 1-dimensional rod-like polymer material, with a mean rod length of 72 nm. The conversion percentages for this material routinely reached 30%, and are expected to improve with purer monomeric materials. The photolysis of the cinnamyl-terminated material routinely reach 70% conversion, and resulted in an insoluble material, that allows for photopatterning. Conventional interdigitated microelectrode (IME) measurements made on these materials show conductivities as high as ca. 10⁻⁸Ω⁻¹·cm⁻¹, and mobility values as high as 10⁻³ cm²·V⁻¹s⁻¹. These charge carrier properties, combined with the selective deposition possibilities (i.e. using patterned substrates and/or photolysis techniques) make this class of materials desirable for further investigation and applications in organic based electronic devices.

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17

Anderson, Michele Lynn 1968. "Characterization of organic/organic' and organic/inorganic heterojunctions and their light-absorbing and light-emitting properties." Diss., The University of Arizona, 1997. http://hdl.handle.net/10150/282555.

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Increasing the efficiency and durability of organic light-emitting diodes (OLEDs) has attracted attention recently due to their prospective wide-spread use as flat-panel displays. The performance and efficiency of OLEDs is understood to be critically dependent on the quality of the device heterojunctions, and on matching the ionization potentials (IP) and the electron affinities (EA) of the luminescent material (LM) with those of the hole (HTA) and electron (ETA) transport agents, respectively. The color and bandwidth of OLED emission color is thought to reflect the packing of the molecules in the luminescent layer. Finally, materials stability under OLED operating conditions is a significant concern. LM, HTA, and ETA thin films were grown in ultra-high vacuum using the molecular beam epitaxy technique. Thin film structure was determined in situ using reflection high energy electron diffraction (RHEED) and ex situ using UV-Vis spectroscopy. LM, HTA, and ETA occupied frontier orbitals (IP) were characterized by ultraviolet photoelectron spectroscopy (UPS), and their unoccupied frontier orbitals (EA) estimated from UV-Vis and fluorescence spectroscopies in combination with the UPS results. The stability of the molecules toward vacuum deposition was verified by compositional analysis of thin film X-ray photoelectron spectra. The stability of these materials toward redox processes was evaluated by cyclic voltammetry in nonaqueous media. Electrochemical data provide a more accurate estimation of the EA since the energetics for addition of an electron to a neutral molecule can be probed directly. The energetic barriers to charge injection into each layer of the device has been correlated to OLED turn-on voltage, indicating that these measurements may be used to screen potential combinations of materials for OLEDs. The chemical reversibility of LM voltammetry appears to limit the performance and lifetimes of solid-state OLEDs due to degradation of the organic layers. The role of oxygen as an electron trap in OLEDs has also been verified electrochemically. Finally, a more accurate determination of the offset of the occupied energy levels at the interface between two organic layers has been achieved via in situ monitoring of the UPS spectrum during heterojunction formation.

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18

Jabbour, Rabih Elie. "Characterization of selected immobilized metal-ions using solid phase extraction sorbents." Diss., The University of Arizona, 1998. http://hdl.handle.net/10150/282773.

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Solid phase extraction (SPE) has been developed as an alternative to liquid-liquid extraction (LLE) in the sample preparation process. The advantages of SPE over LLE are that it is a more useful, reliable tool for sample preparation, which offers greater selectivity. The selectivity of an SPE sorbent is vital for the isolation of analyte from a biological matrix containing a myriad of interferences. The use of conventional ion exchange SPE for such an extraction process might not be adequate due to the adverse effects of interfering ions. Metals immobilized on various modified silicas were investigated to determine if the addition of metals improved selectivity. The selectivity of these sorbents was studied by the extraction of analytes from high ionic strength matrices. Extraction selectivity was found to depend on different factors, including the type of bonded species, metal ions used and the analytes, counter ions, sample pH and elution solvent composition. Utilizing coordination complexation between analytes and immobilized metal ions, particularly when different phases are stacked, can increase selectivity for a particular analyte. Metals immobilized by ionic exchange sorbents were observed to retain analytes of tridentate chelation capability more than immobilized metals on bonded chelators. However, bonded chelators were observed to be advantageous because they more strongly retained metal ions, relative to ionic exchangers. The interactions of immobilized silver ions with unsaturated molecules utilizing SPE were investigated. Retention of silver ions was found dependent on the nature of bonded phase. The silver ions immobilized by coordination interactions showed weaker retention than silver immobilized by ionic interactions. Retention of alkenes by silver was found to have higher flow dependence, as compared to ionic exchange or ligand exchange processes. Retention of analytes was observed to depend on a variety of factors, including the type of bonded phase used for silver immobilization, the composition of the elution solvent, steric factors, the degree of unsaturation, the geometry and position of the double bonds of the analyte molecules. Extraction selectivity for geometrical isomers decreased when silver ions were immobilized by long chain cation exchangers versus those on conventional short chain cation exchangers.

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19

Brown, Elizabeth A. 1973. "Rapid aluminum alloy analysis utilizing inductively coupled plasma atomic emission spectrometry." Thesis, McGill University, 1999. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=30351.

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The goal of this study was the exploration of several techniques for the rapid analysis of aluminum pins by ICP-AES (inductively coupled plasma atomic emission spectrometry).
Direct solid sample analysis of the pin by DSI (direct sample insertion) proved to be unfeasible due to incomplete vaporization of the sample from the DSI probe.
A technique called the Real-time Alloy Analysis Technique (RAAT) allowed analyte signals to be monitored during sample digestion (in dilute HCl) and using a ratio method, quantitative results were obtained after a few minutes of initiating sample digestion. This method exhibited fast and simple sample preparation and high precision of <3% relative standard deviation.
An in-solution spark technique (SAD) was used to produce dispersions of the pins in water. The SAD and DSI proved promising as a very rapid sampling technique.

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20

Schweitzer, Melodie A. (Melodie Ann). "Optical depth profiling of thin polymer films and diffusion in membranes by photothermal deflection or "mirage effect" spectroscopy." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=29128.

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Photothermal deflection or 'mirage effect' spectroscopy was applied to the quantitative profiling of the optical absorbers in thin polymer films with depth dependent absorption coefficients. In addition, the mirage effect system instrumentation was designed and constructed. Improvements to the precision and accuracy of the instrumentation were implemented, which allowed for quantitative measurements of optical depth dependent layers to be profiled in samples consisting of thin polymer multilayered films. A theoretical model based on one-dimensional heat conduction was developed and used to analyze the experimental results. Further improvements were made to the model by applying diffraction theory to recover heat flux profiles. This added precision for the analysis was required for use in the inverse problem theory. The results from using this theoretical model were interpreted. The mirage effect technique was applied to the dynamic diffusion of solutions containing ionic species through a perfluorosulphonated ionomer membrane. The recovery of the heat flux profiles (solved using inverse problem theory) enabled the recovery of optical absorption profiles, and therefore, concentration profiles. A diffusion model (also developed in this work), enabled the diffusion coefficients of these species to be determined from the concentration profiles. By these means, the diffusion processes of species into the membrane were examined.

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21

Smolenyak, Paul Eric 1959. "Synthesis and characterization of new octasubstituted phthalocyanines: Supramolecular materials for thin film electronic, optical and chemical sensor applications." Diss., The University of Arizona, 1998. http://hdl.handle.net/10150/282774.

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The synthesis, structure, and properties of a number of new octasubstituted phthalocyanines, were investigated in this work. Substituent functionality and design has a profound influence on the film forming, and hence, chemical/physical properties of these model molecular electronic materials. Highly ordered thin films, of the benzyl terminated Pc, (2,3,9,10,16,17,23,24-octa(2-benzyloxyethoxy) phthalocyaninato) copper, CuPc(OC₂OBz)₈ and its di-hydrogen analogue were prepared and characterized. These materials form ordered Langmuir films composed of close packed columnar assemblies. Full compression of these materials produces thin films of stable bilayers that show remarkable mechanical stability, and can be transferred with high efficiency to substrates using a horizontal transfer protocol. The physical, spectroscopic, spectroelectrochemical, electrochemical, and electronic properties of these materials were characterized. These properties are strongly dependent on film morphology and structure. The conductivity of these materials relative to the Pc column axis, is highly anisotropic, and with electrochemical doping, the conductivity along the column axis is ca. 10⁻⁶ S/cm. 2,3,9,10,16,17,23,24-Octa(2-benzyloxytriethoxy) phthalocyaninato) copper, and di-hydrogen materials were prepared and characterized. These Pc derivatives did not exhibit the extraordinary properties of their shorter chained analogues. Film preparation efforts with these materials produced poorly ordered isotropic films. Chain length and benzyl termination are combined, in CuPc(OC₂OBz)₈, to produce a unique self assembling material with properties comparable to that reported previously for rigid-rod polymeric Pc materials.

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22

Baumann, Hannah J. "MOLECULAR INVESTIGATION INTO SPINAL CORD INJURY REGENERATION BARRIERS AND THERAPEUTIC STRATEGIES." University of Akron / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=akron1590662448091686.

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23

Georgescu, Nicholas Stefan. "Theoretical and Experimental Aspects of Electrocatalysis of the Oxygen Reduction Reaction and Related Systems." Case Western Reserve University School of Graduate Studies / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=case1481812694657585.

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24

Dunphy, Darren Robert. "Ultrasensitive spectroelectrochemistry of monolayer and submonolayer thin films using an electroactive integrated optical waveguide." Diss., The University of Arizona, 1999. http://hdl.handle.net/10150/282882.

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To increase the applicability of spectroelectrochemistry to ultrathin films at a transparent semiconductor electrode, a single-mode, step-index electroactive integrated optical waveguide (the EA-IOW) incorporating an indium tin oxide top layer as an electrode was developed. The EA-IOW is much more sensitive to absorbance by molecular adlayer species than previous electroactive waveguide designs; a sensitivity increase of ca. 4000 relative to a single-pass transmission experiment has been measured by monitoring the reduction of a surface-adsorbed dye molecule. An important characteristic of the present three-layer EA-IOW structure is that its design is close to being optimized in terms of maximizing sensitivity while maintaining acceptable optical losses, as determined by theoretical modeling. Before the EA-IOW can be applied to measure absorbance changes arising from electron transfer in ultrathin films, the background optical changes that occur as a function of potential must be understood. There is a linear decrease in outcoupled intensity as the EA-IOW is scanned negative which is a result of an increase in the number of free carriers inside the ITO, a highly reproducible effect. There is also a poorly reproducible non-linear component to the optical background, accompanied by a hysteresis between the forward and reverse potential scans, that disappears after conditioning the EA-IOW in electrolyte solution for a period of several days. It is hypothesized that his effect is due to hydroxylation of the ITO network. To test the EA-IOW experimentally, the reduction of surface-adsorption methylene blue was monitored, along with the formation of Prussian blue during the electrochemistry of ferricyanide. Two experimental applications of the EA-IOW will be reviewed; first, the EA-IOW was used to measure the spectroelectrochemistry of submonolayer films of phthalocyanine polymeric assemblies to compare the electrochemistry at submonolayer and multilayer coverages. Finally, the use of the EA-IOW in protein electrochemistry will be discussed. The dichroic ratio of cytochrome c adsorbed to indium tin oxide was measured as a function of potential, and found to be consistent with an orientation of the heme ligand that is almost parallel to the electrode surface. Also, a change in heme orientation was detected during reduction of the protein.

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25

Qi, Peihao 1957. "Leaching and electrochemical behavior of gold in iodide solutions." Thesis, The University of Arizona, 1990. http://hdl.handle.net/10150/291587.

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Of the halogens, the gold iodide complexes are the most stable in aqueous solutions. A series of experiments was performed to investigate the kinetics and mechanism of the leaching reaction between gold and iodide. Using a rotation disk technique, the most important kinetic parameters were measured. The reaction rate was found to be first order with respect toI⁻₃ and half order with respect to I⁻. A gold leaching rate of about 2.6 x 10⁻⁹ mol/cm²·sec for 10⁻² M I⁻ and 5 x 10⁻³ M I₂ was obtained. This value is close to that for typical cyanidation. The reaction rate appears to be controlled mainly by diffusion of reactants through the boundary layer of solution to the gold electrode under the conditions studied. The electrochemical study of gold in different halide solutions, with emphasis on iodide, was also carried out. The electrochemical techniques used in this investigation include cyclic voltammetry and linear sweep voltammetry. The results displayed the sequential oxidation for gold dissolution in iodide solution and confirmed that iodide has the strongest oxidation capability of dissolving gold of the halides.

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26

Deng, Fan. "Photon Upconversion Based on Triplet-Triplet Annihilation." Bowling Green State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1395249331.

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27

McCarthy, Jeffrey J. "Potentiometric microsensors and telemetry." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=39268.

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The use of ion-selective field-effect transistors (ISFETs) as potentiometric microsensors was investigated. In the first stage, an instrument was designed and built to operate an array of ISFETs. A microcomputer was used for instrument control and acquisition of data.
The second phase of research focussed on the development of a pH sensitive radiotelemetric device that could eventually be used for the noninvasive monitoring of gastric pH. The first attempt used an ISFET as a variable resistor in a simple telemetry circuit. The drift in the pH dependent signal from this device was significant. The use of a differential sensor was studied as a possible way to minimize the effect of signal drift. This system measured the differential output of a pH ISFET and a pH insensitive ISFET. The pH insensitivity was due to an alkanethiol monolayer at the ISFET$ vert$solution interface.
It was shown that ISFETs are well suited for use as sensors in telemetry devices. The union of these previously independent research areas has been achieved.

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28

Anderson, Jeffrey David. "Characterization and synthesis of organic semiconductor materials for light-emitting diodes: Structure-property relationships." Diss., The University of Arizona, 1999. http://hdl.handle.net/10150/284304.

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Light generation in organic light emitting diodes (OLEDs) requires the recombination of electron-hole pairs at a p-n junction. Radiative recombination has been investigated with solution electrochemical studies of the principal lumophores, dopants, and hole-transport agents of small molecule OLEDs. We have found that solution electrogenerated chemiluminescent (ECL) reactions between radical anion and cation states of OLED components model the spectral output and efficiency of solid-state electroluminescence. These studies have shown that the molecular structures of commonly used materials in OLEDs are not optimized. ECL has been used to develop and optimize new materials that dramatically improve device performance. The results of the ECL experiments can be explained using commonly accepted electron transfer theories. Nonaqueous electrochemistry and spectroelectrochemistry have been used to study the energetics and stability of radical cation states of new and existing biphenyl-bis-triarylamines (TPDs), triphenylamines, and carbazoles, common hole-transport materials in OLEDs. We have established that these triarylamines, upon anodic oxidation, cation radicals with widely variable stability that react via coupling-deprotonation to form a neutral dimer. We have quantified the decay of these reactions by following the visible absorption decay of the cation radicals. The stability of these states to dimerization reactions is critically dependent on molecular structure. We speculate that these dimerization reactions could occur in the solid state, and that this reaction could lead to OLED degradation, since it involves the loss of a proton. Derivatives of 9,10-diphenylanthracene were synthesized for use as Forster energy transfer dopants and stable charge traps in OLEDs. Cyclic voltarnmetry shows that these compounds form stable radical cation and anion states in nonaqueous electrolytes. Introduction of substituents to the anthracene ring can modify the HOMO - LUMO gap of these structures. When these molecules are doped into poly(N-vinylcarbazole), they act as Foster energy acceptors. Photoluminescent and electroluminescent spectra of these doped polymer composite films show that the luminescence originates from the singlet excited state of the diphenylanthracenes. Preliminary results of single layer OLEDs made from these materials are promising; device external quantum efficiencies attained up to ca. 1.2 % and brightness up to 800 cd/m² at 12 volts.

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29

Guo, Zhenrong. "Characterization of ionic, dipolar and molecular mobility in polymer systems." W&M ScholarWorks, 2005. https://scholarworks.wm.edu/etd/1539623474.

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Changes in the ionic and dipolar molecular mobility in a polymer system are the basis for the changes in the dielectric mechanical properties of polymer materials. Frequency Dependent Dielectric Measurements (FDEMS) and Ion Time-of-Flight (ITOF) are two important techniques to investigate ionic and dipolar molecular mobility in polymer systems. The results can be related to the macro- and molecular dielectric, electrical and dynamic properties of polymeric materials. The combination of these two methods provides a full view of electric, dielectric and dynamic behavior for the systems as they undergo chemical and/or physical changes during polymerization crystallization, vitrification, and/or phase separation.;The research on microscopic mass mobility in polymer systems was done on three aspects: (1) ion mobility in an epoxy-amine reaction system; (2) dipolar mobility and relaxation during dimethacrylate resin cure and (3) dye molecule migration and diffusion in polymer films.;In the ion mobility study, we separately monitor the changes in the ion mobility and the number of charge carriers during the epoxy-amine polymerization with FDEMS and ITOF measurements. The isolation of the number of carriers and their mobility allows significant improvement in monitoring changes in the state and structure of a material as it cures.;For the dipolar mobility and relaxation study, FDEMS measurements were used to detect structural evolution and spatial heterogeneity formation during the polymerization process of dimethacrylate resins. The dielectric spectra, glass transition (Tg) profiles and dynamic mechanical measurements were used to investigate the existence of two cooperative regions of sufficient size to create two alpha-relaxation processes representing oligomer rich and polymer microgel regions during the polymerization.;For the dye migration research, we tried to develop a visually color changing paper (VCP) due to dye molecule migration in polymer films. The mobility of dye molecules in polyvinyl films was controlled by the acidity of the environment. Ionamine derivatives of dyes were stable when mixed with acid. their diffusion in polymer films can be quickly triggered as the result of an acid/base neutralization reaction. The effect of the type of base, acid and the compatibility of polymer films on the diffusion rate is discussed.

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30

Brenan, Colin John Herbert. "Design, operation and applications of a visible-light confocal scanning Fourier transform Raman microscope for volumetric Raman spectrochemical imaging." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=41989.

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A new type of confocal Raman microscope called a Fourier transform confocal Raman microscope (FT-CRM) was designed, built and characterized with respect to its spatio-spectral imaging properties. Several different applications of the FT-CRM are presented that take advantage of its unique spectral and spatial imaging characteristics. The instrument combines focused illumination with spatially-filtered detection in a confocal optical configuration to collect photons scattered from a diffraction-limited volume in the sample (typically ${<}5 times10 sp{-18} m sp3)$ and reject photons from outside that region. The molecular vibrational information encoded in the inelastic, or Raman, spectral component of light scattered from the confocal volume is measured with a visible light Fourier transform Raman spectrometer. By scanning the sample relative to the confocal volume, a volumetric Raman spectrochemical image of the sample can be constructed.
Raman scattering is an inherently inefficient process; hence an optimal radius pinhole must be found that balances the FT-CRM optical throughput against the microscope spatial resolution and image contrast. Detailed experimental measurements mapped out the FT-CRM spatial response (axial and lateral), optical throughput and image signal-to-background and signal-to-noise ratios as a function of pinhole radius. Excellent agreement was found between these measurements and the predictions of a theoretical microscope model also developed as part of this thesis. Several applications of the FT-CRM included volumetric compositional imaging of three-dimensional chemically inhomogeneous materials such as cellulose and polyester fibers in water or two immiscible optically-similar liquids, water and trichloroehthylene, in a porous quartz sandstone matrix. The potential of the FT-CRM for non-invasive spectrochemical detection and imaging through a turbid tissue-like medium was demonstrated and a new spectral estimator, Fast Orthogonal Search, was evaluated to replace the discrete Fourier transform to improve the microscope performance.

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31

Hoh, Eunha. "Investigation of organochlorine and organobromine contaminants in the atmosphere." [Bloomington, Ind.] : Indiana University, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:3204532.

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Thesis (Ph. D.)--Indiana University, School of Public and Environmental Affairs, 2006.
Source: Dissertation Abstracts International, Volume: 67-01, Section: B, page: 0156. Adviser: Ronald A. Hites. "Title from dissertation home page (viewed Feb. 22, 2007)."

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32

Wiklund, Martin. "Ultrasonic Enrichment of Microparticles in Bioaffinity Assays." Doctoral thesis, KTH, Physics, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3729.

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This Thesis describes applications of standing-waveultrasonic traps for sensitive biomedical analysis. Two majorapproaches have been investigated where functionalizedmicroparticles are employed in bioaffinity assays. In the firstapproach, a longitudinal flow-through capillary ultrasonic trapis used for size selective separation and retention ofdifferently sized microparticles. This device may be used fordetection of particle pairs, which are formed during theinitial stage of microparticle immunoagglutination. Theperformance of the capillary ultrasonic trap for enrichment andcounting of particle pairs is characterized by a model systemof differently sized homogeneous fluorescent microparticles.The selectivity of this detection method relies on thecharacteristics of the force field inside the narrow borecapillary, which is formed by the competition between acousticradiation forces and viscous drag forces from the fluidflow.

The second approach is an investigation of the potential forsensitive protein quantification by combining ultrasonicenrichment and confocal laser-scanning fluore-scence detection.Here, the design of the ultrasonic trap is tailor-made for theimaging properties of a confocal microscope, resulting inrearrangement and concentration of suspended microparticlesinto single, dense layers that is scanned by a focused laserbeam. The bioaffinity assay employed is based on detecting thetarget molecules via fluorescent tracer antibodies immobilizedon the surface of each single particle.

The final part of the work presented in this Thesis is athorough investigation of both the biochemical and the physicalproperties that determine the performance and potentialsensitivity of the particle doublet assay. In thisinvestigation, a novel approach is presented for doubletdetection, namely fluorescence-microscopy-based classificationof doublets and singlets by a pattern recognition algorithm.The experimental results are also compared with the resultsfrom flow cytometry analysis. Furthermore, the initial stage ofimmuno-agglutination is theoretically investigated by a modelbased on diffusion-limited agglutination combined with a stericfactor determined by the geometry of the bio-molecules and theamount of specific and non-specific binding that is present inthe particular assay.

To conclude, the Thesis presents several approaches wherestanding-wave ultrasonic fields may be used for sensitiveparticle-based biomedical analysis. The best prospect for highsensitivity was found for the confocal laser-scanningfluorescence detection system, with a detection limit of theorder of 10^-14M. On the other hand, the agglutination-basedassay may give sensitivity of the order of 10^-11-10^-10M with very simple and inexpensiveequipment.

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33

Clymer, John Owen 1960. "Development of a palladium electrode oxygen sensor." Thesis, The University of Arizona, 1992. http://hdl.handle.net/10150/291974.

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This thesis investigates the nature of the potential variations in an electrochemical cell. The cell consists of palladium electrodes immersed in a phosphate buffer electrolyte with a Ag/AgCl double junction reference electrode. The relaxation response of the electrodes to an applied potential is examined and current-potential curves ("voltammograms") are generated by plotting the current flowing through an external circuit versus the measured electrode potential. These graphs show regions of hydrogen adsorption/desorption and areas of oxygen adsorption/desorption. The response of the cell to both nitrogen and oxygen "sparging," a technique that alters the gas concentration of the electrolyte, is also studied. Under these conditions, the potential fluctuates in a predictable manner. In addition, the voltage variations of palladium electrodes inserted into stems of tomato plants is investigated to compare results. The goal of this project is to provide evidence supporting the "Oxygen Hypothesis."

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34

Chen, Siying. "Characterization of crystalline and solution-processable phthalocyanine assemblies by electrochemical, photoelectrochemical, and surface spectroscopic techniques." Diss., The University of Arizona, 1996. http://hdl.handle.net/10150/282120.

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Ultrathin organized films of organic electronic materials, such as phthalocyanines (Pc), are promising for both fundamental and applied studies due to their special optical, electronic and photoconductive properties. The studies presented in this dissertation include fabrication of ultrathin molecular assemblies by molecular beam epitaxy and Langmuir-Blodgett techniques. The degree of molecular order, extent of charge transfer and the morphology within these films, assessed by methodologies, such as photoelectrochemistry, electrochemistry, surface analysis and optical spectroscopy were discussed and characterized. Under high vacuum condition, a wide range of ordered structures of some trivalent metal phthalocyanines, such as GaPc-Cl, InPc-Cl and AlPc-F, can be fabricated. These materials exhibit "layer-by-layer" growth on the single crystal SnS₂ surface when deposited by molecular beam epitaxy (MBE). The MBE technique allows for closer packing of these highly ordered phthalocyanines than in self-assembled (SA) or Langmuir-Blodgett (LB) thin films, due to the lack of hydrocarbon side chains which are necessary for control of molecular architecture during SA or LB depositions. Several new solution processable substituted phthalocyanines are introduced, which due to their strong self-assembled tendency, may be suitable for the formation of well organized thin films by SA and LB techniques. It is found that the types of the substituents attached to the Pc rings play a significant role in determining both the aggregation tendency and the electrochemical properties of Pcs. Surface pressure-area isotherms of these substituted phthalocyanines show that there can be one or two stable phase transition regimes for monomolecular film at the air/water interface. On-trough spectroscopic studies of benzylalkoxy substituted phthalocyanines show that in the pressure-area region prior to the formation of the first stable phase extensive aggregation has occurred. Electrochemical studies of fully compressed films of substituted phthalocyanines on certain substrates show the presence of multiple electroactive domains, controlling the oxidation or reduction process of the Pc rings. Spectroelectrochemical studies of LB films of CuPcOC₂OBz suggest that the presence of both monomer and aggregates leads to the two separate oxidation processes.

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35

Wong, Ka Chun. "Focused Ion Beam Nanomachining of Thermoplastic Polymers." Thesis, North Carolina State University, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=3538536.

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Commercially available Ga⁺ focused ion beam (FIB) instruments with nanometer size probe allows for in situ materials removal (sputtering) and addition (deposition) on a wide range of material. These spatially precise processes have enabled a wide range of nanofacbrication operations (e.g. specimen preparation for analysis by scanning electron microscope, transmission electron microscope, and secondary ion mass spectrometer). While there exists an established knowledge of FIB methods for sample preparation of hard materials, but FIB methodology remain underdeveloped for soft materials such as biological and polymeric materials.

As FIB is increasingly utilized for specimen preparation of polymeric materials, it is becoming necessary to formulate an information base that will allow established FIB techniques to be generalized to this spectrum of materials. A thorough understanding of the fundamental ion-solid interactions that govern the milling process can be instrumental. Therefore, in an effort to make the existing procedures more universally applicable, the interrelationships between target material, variable processing parameters, and process efficiency of the milling phenomena are examined. The roles of beam current, distance (i.e. step size) between successive FIB beam dwell and the time it spent at each dwell point (i.e. pixel dwell time) are considered as applied to FIB nanomachining of four different thermoplastic polymers: 1. low density polyethylene (LDPE), 2. high density polyethylene (HDPE), 3. Polystyrene (PS), and 4. nylon 6 (PA6). Careful characterization of such relationships is used to explain observed phenomena and predict expected milling behaviors, thus allowing the FIB to be used more efficiently with reproducible results. Applications involving different types of polymer composite fiber are presented.

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36

Bacani, Vincent J. (Vincent Joseph). "Development of a rapid colourimetric assay for resin and fatty acids in pulp and paper mill effluents." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=23253.

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Researchers have linked resin and fatty acids (RFAs) to acute toxicity, especially in thermomechanical and chemithermomechanical pulp and paper mill effluents. Thus, the measurement of total RFAs may be a rapid, inexpensive alternative to standard methods of toxicity monitoring, such as 96-hour rainbow trout testing. Current procedures for the analysis of RFAs typically involve solvent extraction and concentration, derivatization, and analysis by GC, HPLC, or TLC. These procedures are far too expensive, complicated, and time-consuming for implementation at mill sites.
This thesis reports the development of a rapid, colourimetric assay based on the dye methylene blue (MB) for the quantification of resin and fatty acids in pulp and paper mill effluents. This MB assay uses the complexation of the cationic organic dye molecule to the carboxylic acid groups of RFAs to form a measurable chromophore. The electrically neutral, blue-coloured complexes are then extracted into a poorly polar organic solvent, dichloromethane. The measured absorbance at 655 nm is directly related to the total RFA concentration in the effluent sample.
The methylene blue assay is inexpensive and simple to use. It has a method detection limit of 0.589 mg/L total RFA. There are good correlations between the results obtained using the methylene blue assay and a well-established GC assay, and between RFA concentrations measured by the MB assay and acute toxicity measured by Microtox. The assay is sufficiently simple and rapid to be practical for routine in-mill monitoring.

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Huettinger, Karl. "Semi-synthetic proteins for catalytic and analytical applications." Diss., Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/33823.

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Proteins have evolved over millions of years to serve a plethora of highly specialized functions in biological systems. Given the enormous diversity in structure and function, it is truly surprising that only 20 different amino acids are utilized as the building blocks of proteins. Furthermore, only a small set of metal cations that are biologically available are used as structural or catalytically active cofactors in proteins, whereas rare metal cations such as platinum, ruthenium or rhodium remain absent. In the 20th century myriad catalysts, based on non-biological transition metals, emerged that can facilitate numerous organic transformations. The goal of the thesis was to introduce new functions into proteins by attaching platinum metals and fluorescent metal sensors. Thus, semi-synthetic proteins for catalytic and analytical applications were generated. The replacement of organic solvents by environmentally benign solvents such as water is an imperative step towards achieving "green chemistry". The combination of small molecule catalysts with proteins may introduce new functions and take advantage of the benefits of "both worlds" while avoiding their potential drawbacks. Therefore semi-synthetic catalysts were developed for enantioselective organic reactions in aqueous medium. A suitable reaction, reaction conditions and catalytic system for later utilization in a semi-synthetic protein were designed, developed and characterized. Ruthenium porphyrins catalyzed cyclopropanation reactions with fair yields and high stereoselectivity in aqueous medium. The successful reaction in water was a crucial requirement for a catalytically active semi-synthetic protein. Mechanistic studies did not elucidate the actual catalytic species for the formation of the cyclopropanation product and the side-product diethyl maleate; however, new insights were gained from the analysis of potential reaction pathways. Moreover, studies of the influence of axial ligands, resembling likely residues coordinating to the ruthenium metal center in the active site of a semi-synthetic protein, on the carbene formation of ruthenium porphyrins illustrated that coordination of axial ligands may inhibit the catalytic activity. The generation of ruthenium porphyrin based semi-synthetic proteins and their subsequent catalysis of cyclopropanation reactions was carried out. Myoglobin and myoglobin mutants were successfully reconstituted with a heme-like ruthenium carbonyl porphyrin; however, none of the formed semi-synthetic proteins catalyzed the enantioselective cyclopropanation of styrene. Efforts to determine the reconstitution efficiency of the generated semi-synthetic were hampered by problems to purify the generated semi-synthetic proteins that are probably due to non-specific binding of the ruthenium porphyrin to the protein surface. The exploration of labile metal pools of the biologically relevant transition metals copper, iron and zinc in cells was the goal of developing semi-synthetic proteins for analytical applications. Combining fluorescent proteins with colored or fluorescent metal chelators by forming semi-synthetic proteins allows taking advantage of their beneficial properties while avoiding their downsides. This design offers an attractive platform for in vivo metal sensing. Plasmids encoding fluorescent proteins, targeting sequences and AGT or intein fusion domains (necessary for labeling) for eukaryotic and prokaryotic expression were generated. The targeting of intracellular compartments (mitochondria, nucleus and TGN) was successful (confirmed by light microscopy experiments with transfected mammalian cells). In vitro labeling experiments of expressed and purified fusion proteins with rhodamine derivatives succeeded with AGT based fusion proteins; however, labeling of fusion proteins by trans-splicing with split-inteins failed. A new Zinc(II)-chelator was attached to an AGT based protein and the resulting semi-synthetic protein exhibited strong changes of fluorescence in the presence of zinc(II). This represents an important step towards the goal of in vivo cell imaging of labile zinc(II) pools. Despite extensive efforts, all attempts failed to generate a chelator that forms Cu(I)-complexes with the 1:1 stochiometry (ligand:metal) that is necessary for metal sensing with semi-synthetic proteins.

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38

Yang, Lin 1963. "Fabrication of low-loss planar waveguides and development of integrated optical chemical sensors." Diss., The University of Arizona, 1996. http://hdl.handle.net/10150/282134.

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Applications of planar integrated optical waveguide (IOW) technology to problems in surface spectroscopy and optical chemical sensing have been partly limited by the difficulty of producing high quality glass IOWs is. The fabrication of IOWs by the sol-gel method from methyltriethoxysilane and titanium tetrabutoxide precursors has therefore been developed. The physical, chemical, and optical properties of the films were studied using a variety of analytical techniques. The results show that the catalyst used to accelerate the sol-gel reaction strongly influenced the optical quality of the IOW. A novel optical sensing platform was subsequently developed using a sol-gel derived, laminate planar IOW structure. The sensing element is fabricated by coating a sol-gel IOW with a second, porous sol-gel layer in which optical indicator molecules are physically entrapped, yet remain sterically accessible to analytes that diffuse into the pore network. Formation of a complex between the analyte and entrapped indicator is detected via attenuated total reflection (ATR) of light guided in the IOW. Feasibility was evaluated by constructing IOW-ATR sensors for Pb2+ and pH, based on entrapped xylenol orange and bromocresol purple respectively. The response of both sensors was sensitive and rapid. This work was further extended to the development of a new class of gaseous iodine sensors. The sensing principle is based on the detection of a charge transfer complex formed between iodine and phenyl groups that have been incorporated into a porous, methylated glass film. The sol-gel iodine sensor exhibits a linear response to gaseous I2 in the range of 100 ppb to 15 ppm with response and recovery times less than 15 sec. Langmuir-Blodgett (LB) films have also been deposited on a sol-gel IOW from zinc 1,4,8,11,15,18,22,25-octabutoxy-phthalocyanine (ZnPc). Planar waveguide linear dichroism was used to determine molecular orientation in a ZnPc LB monolayer. The IOW-supported ZnPc monolayer was found to exhibit a sensitive spectral response to gaseous I2. The overall optical sensing approach described in this dissertation is technically simple, inexpensive, and applicable to a wide variety of chemical sensing problems.

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39

Angeli, Gyorgy Zsolt 1954. "Development of a photoacoustic gas detector." Diss., The University of Arizona, 1996. http://hdl.handle.net/10150/290608.

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The work detailed in the dissertation has resulted in a photoacoustic gas detector chamber that has been proved to be applicable for measuring very low concentration gas traces in ambient air. Calculation tools were developed for photoacoustic cell design, namely (i) a method estimating the acoustic quality factor of a cavity even for open configurations; and (ii) a technique calculating the effectiveness of light-sound energy conversion. An open, windowless resonant photoacoustic chamber was designed, that has high acoustic quality factor and good noise suppression. In such a chamber neither the window material nor the contamination adsorbed on the window surface can contribute to the generation of unwanted coherent background signal. The most important factor limiting the applications of high quality factor resonant photoacoustic cells is the resonant frequency shift due to the possible temperature and gas density variations in the chamber. To compensate this drift, a unique electronic resonance tracking system was constructed. A calibration experiment applying a grating tuned CO₂ laser was performed. The achieved detection limits were 8 ppb for ethylene, 50 ppt for sulphur-hexafluoride, and 11 ppm for carbon-dioxide. The reliability of the system was determined by three repeated measurement campaigns over a month, and it was found outstanding. The photoacoustic detector system was also tested against a conventional analytical technique and good agreement was found with the colorimetric ammonia detection method recommended by the NIOH.

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Chan, Ka Keung. "SYNTHESIS AND FUNCTIONALITY STUDY OF NOVEL BIOMIMETIC N-GLYCAN POLYMERS." Cleveland State University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=csu162309270958734.

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41

Kaplan, Samuel. "DEVELOPING A METHOD FOR THE ELECTROCEHMICAL CHARACTERIZATION OF NOVELNITROGEN-DOPED CARBONACEOUS CATALYSTS FOR CARBON DIOXIDE REDUCTION." Case Western Reserve University School of Graduate Studies / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=case1626451551046237.

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42

Williams, Ammon N. "MEASUREMENT OF RARE EARTH AND URANIUM ELEMENTS USING LASER-INDUCED BREAKDOWN SPECTROSCOPY (LIBS) IN AN AEROSOL SYSTEM FOR NUCLEAR SAFEGUARDS APPLICATIONS." VCU Scholars Compass, 2016. http://scholarscompass.vcu.edu/etd/4631.

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The primary objective of this research is to develop an applied technology and provide an assessment for remotely measuring and analyzing the real time or near real time concentrations of used nuclear fuel (UNF) elements in electrorefiners (ER). Here, Laser-Induced Breakdown Spectroscopy (LIBS) in UNF pyroprocessing facilities was investigated. LIBS is an elemental analysis method, which is based on the emission from plasma generated by focusing a laser beam into the medium. This technology has been reported to be applicable in solids, liquids (includes molten metals), and gases for detecting elements of special nuclear materials. The advantages of applying the technology for pyroprocessing facilities are: (i) Rapid real-time elemental analysis; (ii) Direct detection of elements and impurities in the system with low limits of detection (LOD); and (iii) Little to no sample preparation is required. One important challenge to overcome is achieving reproducible spectral data over time while being able to accurately quantify fission products, rare earth elements, and actinides in the molten salt. Another important challenge is related to the accessibility of molten salt, which is heated in a heavily insulated, remotely operated furnace in a high radiation environment within an argon gas atmosphere. This dissertation aims to address these challenges and approaches in the following phases with their highlighted outcomes: 1. Aerosol-LIBS system design and aqueous testing: An aerosol-LIBS system was designed around a Collison nebulizer and tested using deionized water with Ce, Gd, and Nd concentrations from 100 ppm to 10,000 ppm. The average %RSD values between the sample repetitions were 4.4% and 3.8% for the Ce and Gd lines, respectively. The univariate calibration curve for Ce using the peak intensities of the Ce 418.660 nm line was recommended and had an R2 value, LOD, and RMSECV of 0.994, 189 ppm, and 390 ppm, respectively. The recommended Gd calibration curve was generated using the peak areas of the Gd 409.861 nm line and had an R2, LOD, and RMSECV of 0.992, 316 ppm, and 421 ppm, respectively. The partial least squares (PLS) calibration curves yielded similar results with RMSECV of 406 ppm and 417 ppm for the Ce and Gd curves, respectively. 2. High temperature aerosol-LIBS system design and CeCl3 testing: The aerosol-LIBS system was transitioned to a high temperature and used to measure Ce in molten LiCl-KCl salt within a glovebox environment. The concentration range studied was from 0.1 wt% to 5 wt% Ce. Normalization was necessary due to signal degradation over time; however, with the normalization the %RSD values averaged 5% for the mid and upper concentrations studied. The best univariate calibration curve was generated using the peak areas of the Ce 418.660 nm line. The LOD for this line was 148 ppm with the RMSECV of 647 ppm. The PLS calibration curve was made using 7 latent variables (LV) and resulting in the RMSECV of 622 ppm. The LOD value was below the expected rare earth concentration within the ER. 3. Aerosol-LIBS testing using UCl3: Samples containing UCl3 with concentrations ranging from 0.3 wt% to 5 wt% were measured. The spectral response in this range was linear. The best univariate calibration curves were generated using the peak areas of the U 367.01 nm line and had an R2 value of 0.9917. Here, the LOD was 647 ppm and the RMSECV was 2,290 ppm. The PLS model was substantially better with a RMSECV of 1,110 ppm. The LOD found here is below the expected U concentrations in the ER. The successful completion of this study has demonstrated the feasibility of using an aerosol-LIBS analytical technique to measure rare earth elements and actinides in the pyroprocessing salt.

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43

Cheheltani, Rabee. "Development of infrared spectroscopic methods for assessment of extracellular matrix changes in cardiovascular diseases." Thesis, Temple University, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3623127.

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Extracellular matrix (ECM) is a key component and regulator of many biological tissues. Several cardiovascular pathologies are associated with significant changes in the composition of the matrix. Better understanding of these pathologies and the physiological phenomenon behind their development depends on reliable methods that can measure and characterize ECM content and structure. In this dissertation, infrared spectroscopic methodologies are developed to study the changes in extracellular matrix of cardiovascular tissue in two cardiovascular pathologies; myocardial infarction and abdominal aortic aneurysm.

The specific aims of this dissertation were: 1. To develop a Fourier transform infrared imaging spectroscopy (FT-IRIS) methodology for creating distribution maps of collagen in remodeled cardiac tissue sections after myocardial infarction, and to quantitatively compare maps created by FT-IRIS with conventional staining techniques. 2. To develop an FT-IRIS method to assess elastin and collagen composition in the aortic wall. This will be accomplished using ex vivo animal aorta samples, where the primary ECM components of the wall will be systematically enzymatically degraded. 3. To apply the newly developed FTIR imaging methodology to evaluate changes in the primary ECM components (collagen and elastin) in the wall of human AAA tissues. The infrared absorbance band centered at 1338 ^cm-1, was used to map collagen deposition across heart tissue sections of a rat model of myocardial infarction, and was correlated strongly in the size of the scar (R=0.93) and local intensity of collagen deposition (R=0.86).

In enzymatically degraded pig aorta samples, as a model of ECM degradation in abdominal aortic aneurysm (AAA), partial least squares (PLS) models were created to predict collagen and elastin content in aorta based on collected FTIR spectra and biochemically measured values. PLS models based on FT-IRIS spectra were able to predict elastin and collagen content of the samples with strong correlations (^R2=0.90 and 0.70 respectively). Elastin content prediction from IFOP spectra was successful through a PLS regression model with high correlation (^R2=0.81).

The PLS regression coefficient from the FT-IRIS models were used to map collagen and elastin human AAA biopsy tissue sections, creating a similar map of each component compared to histologically stained images. The mean value of collagen deposition in each tissue was calculated for 13 pairs of AAA samples where stress had been calculated using finite element modeling. In most pairs with stress values higher than 5 N/m², collagen content was lower in the sample with higher stress value. Collagen maturity had a weak negative correlation (R=-0.35) with collagen content in these samples.

These results confirm that infrared spectroscopy is a powerful tool that can be applied to replace or complement conventional methods such as histology and biochemical analysis to characterize ECM components in cardiovascular tissues. Furthermore, infrared spectroscopy has the potential for translation to a clinical environment to examine ECM changes in aorta in a minimally invasive fashion using fiber optic technology.

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44

Vedanbhatla, Naga V. K. Abhinav. "Distributed Approach for Peptide Identification." TopSCHOLAR®, 2015. http://digitalcommons.wku.edu/theses/1546.

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A crucial step in protein identification is peptide identification. The Peptide Spectrum Match (PSM) information set is enormous. Hence, it is a time-consuming procedure to work on a single machine. PSMs are situated by a cross connection, a factual score, or a probability that the match between the trial and speculative is right and original. This procedure takes quite a while to execute. So, there is demand for enhancement of the performance to handle extensive peptide information sets. Development of appropriate distributed frameworks are expected to lessen the processing time. The designed framework uses a peptide handling algorithm named C-Ranker, which takes peptide data as an input then identifies the accurate PSMs. The framework has two steps: Execute the C-Ranker algorithm on servers specified by the user and compare the correct PSM’s data generated via the distributed approach with the normal execution approach of C-Ranker. The objective of this framework is to process expansive peptide datasets utilizing a distributive approach. The nature of the solution calls for parallel execution and hence a decision to implement the same in Java has been taken. The results clearly show that distributed C-Ranker executes in less time as compared to the conventional centralized CRanker application. Around 66.67% of the overall reduction in execution time is shown with this approach. Besides, there is a reduction in the average memory usage with the distributed system running C-Ranker on multiple servers. A great significant benefit that may get overlooked is the fact the distributed CRanker can be used to solve extraordinarily large problems without incurring expenses for a powerful computer or a super computer. Comparison of this approach with An Apache Hadoop Framework for peptide identification with respect to the cost, execution times and flexibility were discussed.

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Lee, Woo Hyoung. "Development and Use of Microelectrodes to Evaluate Nitrification within Chloraminated Drinking Water System Biofilms, and the Effects of Phosphate as a Corrosion Inhibitor on Nitrifying Biofilm." University of Cincinnati / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1258489526.

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46

Hoover, Robert R. Jr. "New Method for Coating Nickel with Ultrathin Platinum Films." Kent State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=kent1274984392.

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47

Lenart, William R. "EXPANDING EXPERIMENTAL AND ANALYTICAL TECHNIQUES FOR THE CHARACTERIZATION OF MACROMOLECULAR STRUCTURES." Case Western Reserve University School of Graduate Studies / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=case1584358701735061.

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48

Liu, Hui Qing 1957. "Fingerprinting biological materials." Thesis, The University of Arizona, 1992. http://hdl.handle.net/10150/291369.

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A study for non-destructive measurement and analysis of agricultural products was undertaken. Some enhancements were made to a spectrophotometer, DK-2A to meet the requirements of low uniform error band when using the factor analysis method. The instrument was modified by adding an integrating sphere, optical transducer, and electronic interface linked to a computer. The instrument was calibrated using targets traceable to NITS standards of BaSO₄ with mixtures of Carbon Black. This gave a range of known reflectance and provided consistent and reproducible data every 5 nm wavelengths between 350 nm and 800 nm. The spectral wavelength bands of the different biological materials were studied with target factor analysis. Target factors were applied in biological materials to characterize the important spectral properties. Pigment of foods, chlorophyll, carotenoid and myoglobin were separated from the spectral response of oranges, apples and meat. Their respective spectral signatures were determined.

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49

Wang, Wenfeng. "Investigation of Energy Alignment Models at Polymer Interfaces." Scholar Commons, 2014. https://scholarcommons.usf.edu/etd/5148.

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The presented study investigated the Induced Density of Interface States (IDIS) model at different polymer interfaces by using photoemission spectroscopy in combination with electrospray deposition. In recent years, organic electronics have attracted considerable attention due to their advantages of low-cost and easy-fabrication. The performance of such devices crucially depends on the energy barrier that controls the interface charge transfer. A significant effort has been made to explore the mechanisms that determine the direction and magnitude of charge transfer barriers in these devices. As a result of this effort, the IDIS model was developed to predict the energy alignment at metal/organic and organic/organic interfaces. The validity of the IDIS model on molecular interfaces was confirmed by the results of a series of experiments with small molecular materials, which are in good agreement with the theoretical calculations from the IDIS model. The charge neutrality level (CNL) and screening factor for various organic materials can be determined from the linear correlation between the hole injection barrier at metal/organic interface and the work function of its corresponding metal substrate, which stands as one of the most important features of the IDIS model. The study presented here explores whether the IDIS model is also valid for polymer interfaces. Two prototypical polymer materials: poly(3-hexylthiophene) (P3HT) and poly[2-methoxy-5-(2'-ethylhexyloxy)-p-phenylene vinylene] (MEH-PPV) were selected for the investigation. In the first part of this study, a series of metal/polymer interfaces were prepared using electrospray and investigated with photoemission spectroscopy. The linear relationship between the hole barriers extracted from the metal/polymer interface and the work function of its respective metal substrate suggests that the IDIS model is also valid for metal/polymer interfaces. The CNLs and the screening factors of P3HT and MEH-PPV are determined respectively. The experiment results are also discussed with regard to the Integer Charge Transfer (ICT) model. The comparison between the two models suggests that the IDIS model should be applied to interfaces prepared in vacuum while the ICT model works on interfaces with an ambient contamination layer present. The second part of the dissertation discusses the photoemission results of the MEH-PPV/P3HT heterojunction from the perspectives of the two models. The results indicate that the IDIS model is valid for polymer/polymer heterojunctions. The IDIS model more accurately predicted the measured orbital line up by using its principles for organic/organic heterojunction than the ICT model.

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Telo, Jasmin. "Conditioning of chromatographic systems prior to metabolomic studies : Investigation of the conditioning effect and the possibility to alter it." Thesis, Uppsala universitet, Avdelningen för analytisk farmaceutisk kemi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-324642.

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The conditioning effect in metabolomic studies is the phenomenon of initial variation of analytical results in the first 5-10 injections of a biological sample in chromatographic systems. The deviation manifests itself as a drift in retention time, peak area and in multivariate analysis. It is a major quality assurance problem in the metabolomic field and if not accounted for would result in high analytical variance. The aim of this study was to investigate the conditioning effect and to gain further knowledge about it. The study was carried out on UPLC of hydrophilic liquid chromatography (HILIC) type coupled to quadrupole time of flight (QTOF) MS. A systematic study was designed to investigate the effects of the age of the analytical column. An investigation into certain matrix components as a possible cause of the conditioning effect was made. Different sample preparation methods were investigated. One result showed that no conditioning could be seen and the system appeared stable from the first injection. Differences in sample composition between samples with conditioning effect and samples without conditioning effect were investigated. No correlation between conditioning effect and levels of certain matrix compounds could be found. More studies of correlation between sample composition and the amount of conditioning occurring is needed. Some samples appear to have no retention time drift but have a significant drift in peak area and in multivariate analysis. This is an indication that the conditioning effect should be analysed in more ways than one before determining if a system is stable.

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Dissertations / Theses on the topic 'Analytical chemistry|Engineering'

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