UNT Theses and Dissertations - 90 Matching Results

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Determination of Molecular Descriptors for Illegal Drugs by Gc-fid Using Abraham Solvation Model

Description: The Abraham solvation parameter model is a good approach for analyzing and predicting biological activities and partitioning coefficients. The general solvation equation has been used to predict the solute property (SP) behavior of drug compounds between biological barriers. Gas chromatography (GC) retention time can be used to predict molecular descriptors, such as E, S, A, B & L for existing and newly developed drug compounds. In this research, six columns of different stationary phases were … more
Date: December 2013
Creator: Akhter, Syeda Sabrina
Item Type: Refine your search to only Thesis or Dissertation
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Determination of Solute Descriptors for Illicit Drugs Using Gas Chromatographic Retention Data and Abraham Solvation Model

Description: In this experiment, more than one hundred volatile organic compounds were analyzed with the gas chromatograph. Six capillary columns ZB wax plus, ZB 35, TR1MS, TR5, TG5MS and TG1301MS with different polarities have been used for separation of compounds and illicit drugs. The Abraham solvation model has five solute descriptors. The solute descriptors are E, S, A, B, L (or V). Based on the six stationary phases, six equations were constructed as a training set for each of the six columns. The si… more
Date: August 2015
Creator: Mitheo, Yannick K.
Item Type: Refine your search to only Thesis or Dissertation
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Development of a Laponite Pluronic Composite for Foaming Applications

Description: The focus of the following research was to provide an optimized particle stabilized foam of Laponite and Pluronic L62 in water by understanding (1) the Laponite-Pluronic interactions and properties for improved performance in a particle stabilized foam and (2) the interfacial properties between air and the Laponite-Pluronic complex. These studies were conducted using both bulk and interfacial rheology, XRD, sessile droplet, TGA and UV-vis. Two novel and simple techniques, lamella break point an… more
Date: December 2012
Creator: Davis, James William
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The Development of an Analytical Microwave Electromagnetic Pulse Transmission Probe and Preliminary Test Results

Description: Within this educational endeavor instrumental development was explored through the investigation of microwave induce stable electromagnetic waves within a non-linear yttrium iron garnet ferromagnetic waveguide. The resulting magnetostatic surface waves were investigated as a possible method of rapid analytical evaluation of material composition. Initial analytical results indicate that the interaction seen between wave and material electric and magnetic fields will allow phase coherence recover… more
Date: May 2011
Creator: Griffith, William Francis
Item Type: Refine your search to only Thesis or Dissertation
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Development of Novel Semi-conducting Ortho-carborane Based Polymer Films: Enhanced Electronic and Chemical Properties

Description: A novel class of semi-conducting ortho-carborane (B10C2H12) based polymer films with enhanced electronic and chemical properties has been developed. The novel films are formed from electron-beam cross-linking of condensed B10C2H12 and B10C2H12 co-condensed with aromatic linking units (Y) (Y=1,4-diaminobenzene (DAB), benzene (BNZ) and pyridine (PY)) at 110 K. The bonding and electronic properties of the novel films were investigated using X-ray photoelectron spectroscopy (XPS), UV photoelectro… more
Date: August 2013
Creator: Pasquale, Frank L.
Item Type: Refine your search to only Thesis or Dissertation
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Direct Atomic Level Controlled Growth and Characterization of h-BN and Graphene Heterostructures on Magnetic Substrates for Spintronic Applications

Description: Epitaxial multilayer h-BN(0001) heterostructures and graphene/h-BN heterostructures have many potential applications in spintronics. The use of h-BN and graphene require atomically precise control and azimuthal alignment of the individual layers in the structure. These in turn require fabrication of devices by direct scalable methods rather than physical transfer of BN and graphene flakes, and such scalable methods are also critical for industrially compatible development of 2D devices. The … more
Date: August 2016
Creator: Beatty, John D.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Direct Inject Mass Spectrometry for Illicit Chemistry Detection and Characterization

Description: The field of direct inject mass spectrometry includes a massive host of ambient ionization techniques that are especially useful for forensic analysts. Whether the sample is trace amounts of drugs or explosives or bulk amounts of synthetic drugs from a clandestine laboratory, the analysis of forensic evidence requires minimal sample preparation, evidence preservation, and high sensitivity. Direct inject mass spectrometry techniques can rarely provide all of these. Direct analyte-probed nanoe… more
Date: May 2016
Creator: Williams, Kristina Charlene
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The Effect of Plasma on Silicon Nitride, Oxynitride and Other Metals for Enhanced Epoxy Adhesion for Packaging Applications

Description: The effects of direct plasma chemistries on carbon removal from silicon nitride (SiNx) and oxynitride (SiOxNy ) surfaces and Cu have been studied by x-photoelectron spectroscopy (XPS) and ex-situ contact angle measurements. The data indicate that O2,NH3 and He capacitively coupled plasmas are effective at removing adventitious carbon from silicon nitride (SiNx) and Silicon oxynitride (SiOxNy ) surfaces. O2plasma and He plasma treatment results in the formation of silica overlayer. In contrast,… more
Date: August 2014
Creator: Gaddam, Sneha Sen
Item Type: Refine your search to only Thesis or Dissertation
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Electrochemical Depostion of Bismuth on Ruthenium and Ruthenium Oxide Surfaces

Description: Cyclic voltammetry experiments were performed to compare the electrodeposition characteristics of bismuth on ruthenium. Two types of electrodes were used for comparison: a Ru shot electrode (polycrystalline) and a thin film of radio-frequency sputtered Ru on a Ti/Si(100) support. Experiments were performed in 1mM Bi(NO3)3/0.5M H2SO4 with switching potentials between -0.25 and 0.55V (vs. KCl sat. Ag/AgCl) and a 20mV/s scan rate. Grazing incidence x-ray diffraction (GIXRD) determined the freshly … more
Date: May 2012
Creator: Taylor, Daniel M.
Item Type: Refine your search to only Thesis or Dissertation
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Electrochemical Quartz Crystal Microbalance Study Of Bismuth Underpotential Deposition On Ruthenium And On Electrochemically Formed Ruthenium Oxide

Description: Kinetics and thermodynamics of bismuth (Bi) underpotential deposition (UPD) on ruthenium (Ru) and on electrochemically formed Ru oxide are studied using electrochemical quartz crystal microbalance technique. The Bi UPD and Bi bulk deposition are observed both on Ru and on electrochemically formed Ru oxide electrodes. The anodic peak potential of Bi UPD shifts slightly to positive potential as the scan rate increases. The peak current ratio (IAnode/ICathode) of Bi UPD and Bi bulk increases as th… more
Date: December 2011
Creator: Lin, Po-Fu
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Electrochemical Synthesis and Applications of Layered Double Hydroxides and Derivatives

Description: Layered double hydroxides (LDH) are a class of anionic clay with alternating layers of positive and negative charge. A metal hydroxide layer with divalent and trivalent metals with a positive charge is complemented by an interlayer region containing anions and water with a negative charge. The anions can be exchanged under favorable conditions. Hydrotalcite (Mg6Al2(OH)16[CO3]·4H2O) and other variations are naturally occurring minerals. Synthetic LDH can be prepared as a powder or film by numero… more
Date: August 2015
Creator: Kahl, Michael S.
Item Type: Refine your search to only Thesis or Dissertation
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Electrochemical Synthesis and Characterization of Inorganic Materials from Aqueous Solutions

Description: The dissertation consists of the following three sections: 1. Hydroxyapatite (HA) coatings. In this work, we deposited HA precursor films from weak basic electrolytic solution (pH= 8-9) via an electrochemical approach; the deposits were changed into crystallite coatings of hydroxyapatite by sintering at specific temperatures (600-800 ºC). The formed coatings were mainly characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microsc… more
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Date: December 2006
Creator: Yuan, Qiuhua
Item Type: Refine your search to only Thesis or Dissertation
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Electrochemically Deposited Metal Alloy-silicate Nanocomposite Corrosion Resistant Materials

Description: Zinc-nickel ?-phase silicate and copper-nickel silicate corrosion resistant coatings have been prepared via electrochemical methods to improve currently available corrosion resistant materials in the oil and gas industry. A layered silicate, montmorillonite, has been incorporated into the coatings for increased corrosion protection. For the zinc nickel silicate coatings, optimal plating conditions were determined to be a working pH range of 9.3 -9.5 with a borate based electrolyte solution, res… more
Date: May 2013
Creator: Conrad, Heidi Ann
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Electrodeposited Metal Matrix Composites for Enhanced Corrosion Protection and Mechanical Properties

Description: In the oil and gas industry, high corrosion resistance and hardness are needed to extend the lifetime of the coatings due to exposure to high stress and salt environments. Electrodeposition has become a favorable technique in synthesizing coatings because of low cost, convenience, and the ability to work at low temperatures. Electrodeposition of metal matrix composites has become popular for enhanced corrosion resistance and hardness in the oil and gas industry because of the major problems tha… more
Date: May 2016
Creator: Thurber, Casey Ray
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries

Electrodeposition of adherent copper film on unmodified tungsten.

Description: Adherent Cu films were electrodeposited onto polycrystalline W foils from purged solutions of 0.05 M CuSO4 in H2SO4 supporting electrolyte and 0.025 M CuCO3∙Cu(OH)2 in 0.32 M H3BO3 and corresponding HBF4 supporting electrolyte, both at pH = 1. Films were deposited under constant potential conditions at voltages between -0.6 V and -0.2 V vs Ag/AgCl. All films produced by pulses of 10 s duration were visible to the eye, copper colored, and survived a crude test called "the Scotch tape test", … more
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Date: May 2004
Creator: Wang, Chen
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Electrodeposition of Copper on Ruthenium Oxides and Bimetallic Corrosion of Copper/Ruthenium in Polyphenolic Antioxidants

Description: Copper (Cu) electrodeposition on ruthenium (Ru) oxides was studied due to important implications in semiconductor industry. Ruthenium, proposed as the copper diffusion barrier/liner material, has higher oxygen affinity to form different oxides. Three different oxides (the native oxide, reversible oxide, and irreversible oxide) were studied. Native oxide can be formed on exposing Ru in atmosphere. The reversible and irreversible oxides can be formed by applying electrochemical potential. Investi… more
Date: August 2007
Creator: Venkataraman, Shyam S.
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Electrodeposition of Diamond-like Carbon Films

Description: Electrodeposition of diamond-like carbon (DLC) films was studied on different substrates using two different electrochemical methods. The first electrochemical method using a three-electrode system was studied to successfully deposit hydrogenated DLC films on Nickel, Copper and Brass substrates. The as-deposited films were characterized by scanning electron microscopy (SEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), fourier transform infrared spectroscopy (FTIR) and cyclic vol… more
Date: August 2002
Creator: Chen, Minhua
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Electrodeposition of Nickel and Nickel Alloy Coatings with Layered Silicates for Enhanced Corrosion Resistance and Mechanical Properties

Description: The new nickel/layered silicate nanocomposites were electrodeposited from different pHs to study the influence on the metal ions/layered silicate plating solution and on the properties of the deposited films. Nickel/layered silicate nanocomposites were fabricated from citrate bath atacidic pHs (1.6−3.0), from Watts’ type solution (pH ~4-5), and from citrate bath at basic pH (~9). Additionally, the new nickel/molybdenum/layered silicate nanocomposites were electrodeposited from citrate bath at p… more
Date: August 2014
Creator: Tientong, Jeerapan
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Experimental Determination of L, Ostwald Solubility Solute Descriptor for Illegal Drugs By Gas Chromatography and Analysis By the Abraham Model

Description: The experiment successfully established the mathematical correlations between the logarithm of retention time of illegal drugs with GC system and the solute descriptor L from the Abraham model. the experiment used the method of Gas Chromatography to analyze the samples of illegal drugs and obtain the retention time of each one. Using the Abraham model to calculate and analyze the sorption coefficient of illegal drugs is an effective way to estimate the drugs. Comparison of the experimental dat… more
Date: May 2012
Creator: Wang, Zhouxing
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Fabrication and light scattering study of multi-responsive nanostructured hydrogels and water-soluble polymers.

Description: Monodispersed microgels composed of poly-acrylic acid (PAAc) and poly(N-isopropylacrylamide) (PNIPAM) interpenetrating networks were synthesized by 2-step method with first preparing PNIPAM microgel and then polymerizing acrylic acid that interpenetrates into the PNIPAM network. The semi-dilute aqueous solutions of the PNIPAM-PAAc IPN microgels exhibit an inverse thermo-reversible gelation. Furthermore, IPN microgels undergo the reversible volume phase transitions in response to both pH and tem… more
Date: December 2003
Creator: Xia, Xiaohu
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Forensic Analysis of Ink on Documents Using Direct Analyte-Probed Nanoextraction Coupled Techniques

Description: Analzying questioned documents in a nondestructive nature has been an issue for the forensic science community. Using nondestructive techniques such as video spectral comparator does not give reliable information due to the variations in gray or color levels that are distinguished differently by analysts. Destructive techniques such as chromatography give dependable, qualitative and quantitative, information but involves altering the evidentiary value of these questioned documents. The paradox … more
Date: May 2016
Creator: Huynh, Vivian
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Forensic Science Applications Utilizing Nanomanipulation-Coupled to Nanospray Ionization-Mass Spectrometry for the Analysis of Ultra-Trace Illicit Drugs

Description: Presented in this thesis are two methods that are coupled to the instrumentation for the recovery and analysis of ultra-trace illicit drug residues. The electrostatic dust lifting process is coupled with nanomanipulation-nanospray ionization to retrieve drug particles off of hard surfaces for analysis. For the second method, drug residues from fingerprint impressions are extracted followed by analysis. The methodology of these hyphenated techniques toward forensic science applications is applie… more
Date: December 2010
Creator: Wallace, Nicole
Item Type: Refine your search to only Thesis or Dissertation
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Free Radical Chemistries at the Surface of Electronic Materials

Description: The focus of the following research was to (1) understand the chemistry involved in nitriding an organosilicate glass substrate prior to tantalum deposition, as well as the effect nitrogen incorporation plays on subsequent tantalum deposition and (2) the reduction of a native oxide, the removal of surface contaminants, and the etching of a HgCdTe surface utilizing atomic hydrogen. These studies were investigated utilizing XPS, TEM and AFM. XPS data show that bombardment of an OSG substrate with… more
Date: August 2010
Creator: Wilks, Justin
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Free Radical Induced Oxidation, Reduction and Metallization of NiSi and Ni(Pt)Si Surfaces

Description: NiSi and Ni(Pt)Si, and of the effects of dissociated ammonia on oxide reduction was carried out under controlled ultrahigh vacuum (UHV) conditions. X-ray photoelectron spectroscopy (XPS) has been used to characterize the evolution of surface composition. Vicinal surfaces on NiSi and Ni(Pt)Si were formed in UHV by a combination of Ar+ sputtering and thermal annealing. Oxidation of these surfaces in the presence of either O+O2 or pure O2 at room temperature results in the initial formation of a S… more
Date: August 2010
Creator: Manandhar, Sudha
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