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Denaturation, Renaturation and Other Structural Studies on Phosphoglucose Isomerases
Structural properties of phosphoglucose isomerases isolated from a variety of species have been compared by peptide fingerprinting, predicted amino acid sequence homologies and by denaturation and renaturation studies. The enzymes are more readily denatured in guanidinium chloride than in urea, and the isomerase isolated from yeast is more stable toward acid pH than the rabbit muscle enzyme. The rates of guanidinium chloride-induced denaturation are markedly increased by ionic strength and decreased by substrates, competitive inhibitors or glycerol. The enzyme can be renatured, but only in the presence of glycerol. The renaturation process is dependent on protein concentration and temperature and provides a method for the formation of mixed species heterodimers.
Date:
December 1975
Creator:
Young, Clint D.
System:
The UNT Digital Library
A Content Originality Analysis of HRD Focused Dissertations and Published Academic Articles using TurnItIn Plagiarism Detection Software
This empirical exploratory study quantitatively analyzed content similarity indices (potential plagiarism) from a corpus consisting of 360 dissertations and 360 published articles. The population was defined using the filtering search criteria human resource development, training and development, organizational development, career development, or HRD. This study described in detail the process of collecting content similarity analysis (CSA) metadata using Turnitin software (www.turnitin.com). This researcher conducted robust descriptive statistics, a Wilcoxon signed-rank statistic between the similarity indices before and after false positives were excluded, and a multinomial logistic regression analysis to predict levels of plagiarism for the dissertations and the published articles. The corpus of dissertations had an adjusted rate of document similarity (potential plagiarism) of M = 9%, (SD = 6%) with 88.1% of the dissertations in the low level of plagiarism, 9.7% in the high and 2.2% in the excessive group. The corpus of published articles had an adjusted rate of document similarity (potential plagiarism) of M = 11%, (SD = 10%) with 79.2% of the published articles in the low level of plagiarism, 12.8% in the high and 8.1% in the excessive group. Most of the difference between the dissertations and published articles were attributed to plagiarism-of-self issues which …
Date:
May 2017
Creator:
Mayes, Robin James
System:
The UNT Digital Library
The Analysis of Volatile Impurities in Air by Gas Chromatography/Mass Spectrometry
The determination of carbon monoxide is also possible by trapping CO on preconditioned molecular sieve and thermal desorption. Analysis in this case is performed by gas chromatography/mass spectroscopy, although the trapping technique is applicable to other suitable GC techniques.
Date:
May 1993
Creator:
Talasek, Robert Thomas
System:
The UNT Digital Library
Deterministic Brownian Motion
The goal of this thesis is to contribute to the ambitious program of the foundation of developing statistical physics using chaos. We build a deterministic model of Brownian motion and provide a microscpoic derivation of the Fokker-Planck equation. Since the Brownian motion of a particle is the result of the competing processes of diffusion and dissipation, we create a model where both diffusion and dissipation originate from the same deterministic mechanism - the deterministic interaction of that particle with its environment. We show that standard diffusion which is the basis of the Fokker-Planck equation rests on the Central Limit Theorem, and, consequently, on the possibility of deriving it from a deterministic process with a quickly decaying correlation function. The sensitive dependence on initial conditions, one of the defining properties of chaos insures this rapid decay. We carefully address the problem of deriving dissipation from the interaction of a particle with a fully deterministic nonlinear bath, that we term the booster. We show that the solution of this problem essentially rests on the linear response of a booster to an external perturbation. This raises a long-standing problem concerned with Kubo's Linear Response Theory and the strong criticism against it by van …
Date:
August 1993
Creator:
Trefán, György
System:
The UNT Digital Library
The Electronic Spectrum of (-)-S-(pS)-2,5,3',6'-Tetrahydro-2.2-Paracyclophane-2-Carboxylic Acid
A new, efficient route was used in the synthesis of [2.2]-paracyclophane-2-carboxylic acid. The acid as then resolved and the Birch reduction performed yielding one enantiomer of tetrahydro-[2.2]-paracyclophane-2-carboxylic acid. The ultraviolet spectrum of tetrahydro-[2.2]-paracyclophane- 2-carboxylic acid in isopenthane shows one absorption at 206 nm (Emax = 5,271). There are three bands observed in the circular dichroism spectrum in isopentane at 236 nm ([] = 1.8 X 104), 201 nm ([0] = -16 X 104) and a positive band indicated below 180 nm but not observed. The bands were assigned and possible reasons for the occurrence of a mr'r* transition at unexpectedly long wavelengths are discussed.
Date:
May 1980
Creator:
Hall, Lindsey
System:
The UNT Digital Library
Evaluation of Adsorption and Microcoulometric Methods for Determination of Halogenated Organic Compounds in Water
Two adsorption/microcoulometric methods have been investigated for total organic halogen (TOX) in water. TOX, a proposed water-quality parameter, is a rapid, surrogate method to detect halides microcoulometrically and does not require compound identification before water quality can be judged. An XAD resin is used to concentrate organic halides that are eluted by a two-step, two-solvent procedure, followed by analysis using :chromatography or pyrolysis to convert organic halides to halide. In the granular activated carbon (GAC) method, the entire GAC-organic halide sample is pyrolyzed. TOX measurements of model compounds are comparable by both methods, but GAC was found to be superior to XAD for adsorption of chlorinated humics in drinking water and chlorinated lake water.
Date:
May 1980
Creator:
Kinstley, Warren O. (Warren Owen)
System:
The UNT Digital Library
Halogenated 2-Oxetanones
The purpose of this investigation is threefold: (1) to examine in detail the cycloaddition of halogenated ketenes and carbonyl compounds, (2) to study the decarboxylation of the resulting halogenated 2-oxetanones,and (3) to investigate the effect of halogens in the halogenated 2-oxetanones on the nucleophilic addition reaction.
Date:
May 1973
Creator:
Patel, Arvind D.
System:
The UNT Digital Library
Hyperconjugative Interactions in Silylanilines
The purpose of the present work is to study the bonding interactions between the substituents and the ring π system for a series of ortho and para MeₙH₃₋ₙM (M = C or Si, n = 0-3) substituted N,N-dimethylaniline . Both ground and excited-state interactions were studied and their magnitudes determined. The experimental data were then used in conjunction with molecular orbital calculations to differentiate among inductive, hyperconjugative, and d-pπ interactions on the ground and excited states. Overall, the study indicates that d orbital involvement in the interactions of organosilicon substituents with unsaturated systems is much less significant than is generally held. The importance of pₛᵢ⁻π and pₛᵢ⁻π* hyperconjugative interactions between silicon σ* orbitals and π system in producing the effects of silicon substitution on unsaturated systems has become more apparent.
Date:
May 1975
Creator:
Jung, Il Nam
System:
The UNT Digital Library
The Influence of Selected Non-Bonded Interactions on Vicinal Carbon-Carbon Coupling Constants
The body of information concerning carbon-carbon spin-spin coupling constants now includes a large number of coupling constants, the establishment of a dihedral angular dependence on 3JCC, and the application of 3JCC to conformational analysis. This study adds another dimension to the growing wealth of information associated with 13 C-NMR: the influence of some non-bonded interactions on 3JCC Four types of non-bonded interactions that could influence vicinal carbon-carbon NMR coupling constants were investigated. To facilitate the NMR studies, a variety of 13C-labeled compounds were synthesized.
Date:
May 1982
Creator:
Canada, Edward D. (Edward Dee)
System:
The UNT Digital Library
Isolation and Characterization of Proteus vulgaris Methylglyoxal Synthetase
Methylglyoxal synthetase, which catalyzes the formation of methylglyoxal and inorganic phosphate from dihydroxyacetone phosphate, was found in extracts of Proteus vulgaris. An efficient purification procedure utilizing ion exchange column chromatography and isoelectric focusing has been developed. Homogeneity of the enzyme preparation was confirmed by polyacrylamide gel electrophoresis and rechromatography.Two components of methylglyoxal synthetase were obtained upon isoelectric focusing. A comparison of the chemical and physical properties of the two components was carried out. The enzyme is a dimer. In the presence of inorganic phosphate, the hyperbolic saturation kinetics with dihydroxyacetone phosphate are shifted to sigmoidal.
Date:
May 1975
Creator:
Tsai, Pei-Kuo
System:
The UNT Digital Library
Long-Range Carbon-13--Carbon-13 Spin-Spin Coupling Constants
The study consists of three major areas of research. First, the dihedral angle dependence of vicinal carbon-carbon coupling constants is determined for aliphatic and alicyclic carboxylic acids wherein the formal hybridization and substituents are held constant. Second, the magnitudes and relative signs of long-range carbon-carbon coupling constants in a. triple- 13 C-labeled system are determined and compared with carbon-proton and/or proton-proton coupling constants in geometrically similar compounds. Third, the effect of changes in hybridization on long-range carbon-carbon coupling constants is determined for the following three groups of molecules: olefins and saturated hydrocarbons, aliphatic carboxylic acids, and aromatic compounds. In all cases only closely related systems are compared in order to identify the effect of individual molecular parameters. Most importantly, the results indicate that carbon-carbon couplings do correlate in magnitude and sign with carbon-proton and proton-proton couplings in analogous molecular. frameworks. Thus, the coupling mechanisms are similar in all three types of coupling. In addition, the observed trends in long-range carbon-carbon couplings provide an unambiguous method for assigning carbon chemical shifts.
Date:
December 1974
Creator:
Miller, Denis E.
System:
The UNT Digital Library
A Materials Approach to Silicon Wafer Level Contamination Issues from the Wet Clean Process
Semiconductor devices are built using hyperpure silicon and very controlled levels of doping to create desired electrical properties. Contamination can alter these precisely controlled electrical properties that can render the device non-functional or unreliable. It is desirable to determine what impurities impact the device and control them. This study consists of four parts: a) determination of acceptable SCI (Standard Clean 1) bath contamination levels using VPD-DSE-GFAAS (Vapor Phase Decomposition Droplet Surface Etching Graphite Furnace Atomic Absorption Spectroscopy), b) copper deposition from various aqueous HF solutions, c) anion contamination from fluoropolymers used in chemical handling and d) metallic contamination from fluoropolymers and polyethylene used in chemical handling. A technique was developed for the determination of metals on a silicon wafer source at low levels. These levels were then correlated to contamination levels in a SCI bath. This correlation permits the determination of maximum permissible solution contaminant levels. Copper contamination is a concern for depositing on the wafer surface from hydrofluoric acid solutions. The relationship between copper concentration on the wafer surface and hydrofluoric acid concentration was determined. An inverse relationship exists and was explained by differences in diffusion rates between the differing copper species existing in aqueous hydrofluoric acid solutions. Finally, …
Date:
December 1996
Creator:
Hall, Lindsey H. (Lindsey Harrison)
System:
The UNT Digital Library
Organometallic Precursors to Cyclic Organosilanes
This investigation deals with the preparations of cyclic organosilanes via two different types of organometallic precursors: borane adducts to chlorovinylsilanes and tertbutyllithium adducts to chlorovinylsilanes. The regiospecificity of the hydroboration of various types of boranes to chlorovinylsilanes was studied by three different methods. It was found that, by using bulky hydroborating agents, about 80% isomerically pure terminal borane adducts to chlorovinylsilanes could be obtained. While the adducts are potential precursors to silacyclopropanes, when these borane adducts were treated with bases such as sodium methoxide and methyl Grignard, no evidence for silacyclopropane formation was found.
Date:
May 1977
Creator:
Lim, Thomas Fay-Oy
System:
The UNT Digital Library
Ozonolysis and Cycloaddition Reaction of (Trimethylsilyl)ketene
The purpose of this investigation was to study the chemistry of the new and novel (trimethylsilyl)ketene. This ketene was synthesized by pyrolysis of (trimethylsilyl)ethoxyacetylene which was prepared from ethoxyacetylene and methyllithium. (Trimethylsilyl)ketene is a very stable and isolable ketene which does not dimerize and, therefore, provides an opportunity for some unique studies that have not been possible with other monosubstituted ketene.
Date:
August 1980
Creator:
Saidi, Kazem
System:
The UNT Digital Library
Reactions of Anions of Cyclic Oximes, Oxime Ethers, and Chiral Imines
The purpose of this investigation is to examine reactions of anions of oximes, oxime ethers and imines with acylating agents and other electrophiles. It is also an attempt to utilize the phenomenon of geometrical enantiomeric isomerism, in which absolute configuration is determined by double bond geometry, and the concept of regiospecific anion formation, also determined by double bond geometry, for stereospecific synthesis of tropinone derivatives.
Date:
August 1980
Creator:
Maloney, John R.
System:
The UNT Digital Library
Reactions of N-(Substituted) Phthalimides with n-Alkylamines
The initial purpose of this study was to determine if steric problems would account for the difference in the products obtained in the reaction of the N-(substituted)phthalimide with low and high molecular weight amines.
Date:
August 1970
Creator:
Johnson, D. Pat
System:
The UNT Digital Library
Rearrangement of Alkylhaloketene-Cyclopentadiene Adducts in Basic Solution--A New Synthesis of 2-Alkyltropones
This research is concerned with determining whether the previously reported synthesis of tropolone by the solvolysis of the dichloroketene-cyclopentadiene adduct in sodium acetate and acetic acid could be used to prepare 2-alkyltropones from the adducts of alkylhaloketenes and cyclopentadiene. The information obtained from these rearrangements could be useful in determining the mechanism of the ring expansion of halogenated ketene-cyclopentadiene adducts to tropone derivatives.
Date:
December 1971
Creator:
Hieble, Jacob Paul, 1948-
System:
The UNT Digital Library
Separation and Characterization of Variant Forms of Phosphoglucose Isomerase: Purification and Structural Analysis of Active Site Peptides from Human and Rabbit Phosphoglucose Isomerase
A method has been developed for the rapid, quantitative separation of normal and abnormal phosphoglucose isoemrase allozymes from individuals heterozygous for genetic variant forms of the enzyme. The method utilizes a substrate gradient elution of the enzyme from carboxymethyl Biogel and is far superior in terms of resolution and recovery to methods based on electrophoresis and isoelectric focusing. Four different genetic variant forms of the enzyme were isolated and subjected to a systematic comparison of their physical, catalytic and stability properties. The physical and catalytic properties of the variants were similar; however, clear differences in the stability of the allozymes were apparent.
Date:
May 1980
Creator:
Gibson, David R.
System:
The UNT Digital Library
Solderability Study of Tin/Lead Alloy Under Steam-Aging Treatment by Electrochemical Reduction Analysis and Wetting Balance Tests
Two types of solder samples, pins and through-holes were tested by SERA™ (Sequential Electrochemical Reduction Analysis) and Wetting Balance after various length of steamaging treatment. It was shown that after steam-aging, both types of specimen gave a similar electrochemical reduction curve, and solderabilty predictions made from SERA™ test agree with results obtained from Wetting Balance test on a qualitative base. Wetting balance test of pin samples after SERA™ test confirmed that SERA™ is a non-destructive testing method -- it even restored solderability. Comparison of electrochemical reduction behavior of samples under different treatment indicates that steam-aging can not reproduce exactly the effect of naturally atmospheric aging, and may not be the best artificial accelerating environment adopted.
Date:
May 1993
Creator:
Gao, Yang, 1966-
System:
The UNT Digital Library
Solid State Diffusion Kinetics of Intermetallic Compound Formation in Composite Solder
The Sn/Pb eutectic alloy system is the most widely used joining material in the electronics industry. In this application, the solder acts as both an electrical and mechanical connection within and among the different packaging levels in an electronic device. Recent advances in packaging technologies, however, driven by the desire for miniaturization and increased circuit speed, result in severe operating conditions for the solder connection. In an effort to improve its mechanical integrity, metallic or intermetallic particles have been added to eutectic Sn/Pb solder, and termed composite solders. It was the goal of this study to investigate the growth and morphology of the two intermetallic phases (Cu6Sn5 and Cu3Sn) that form between a Cu substrate and Sn/Pb solder under different aging and annealing conditions.
Date:
May 1993
Creator:
Sees, Jennifer A. (Jennifer Anne)
System:
The UNT Digital Library
Third World Decolonization: The Pan Africanist Movement in the Age of Nasserism
In the mid-twentieth century Egyptian President Gamal Abdel-Nasser, along with President Kwame Nkrumah of Ghana rose to international prominence as leaders and visionaries who were able to achieve political independence in their respective home countries while attempting to shape a destiny for Africa that did not involve Western imperialism. For Nasser's part, he first secured independence for Egypt, then turned his attention to the Middle East, but soon became as active in the politics of Sub Saharan Africa, also known as black Africa, as he was in the Arab world. This thesis explores Nasser's forays into Sub Saharan Africa during the period of decolonization on the continent and how his aspirations for Africa were equally a part of his political agenda that came to be known as Nasserism. Considering Nasser was the leader of the Third bloc, Egypt's fate was tied to Africa just as much as it was to the Middle East. Beyond the aspects of Nasser's involvement in Africa, this work also explores the active role Africans played in their quest for independence from European colonizers. Many African leaders during this time were as prominent and as shrewd as Nasser and were committed to establishing an anti-imperialist continent …
Date:
May 2017
Creator:
Pendegraft, Gregory
System:
The UNT Digital Library
Impact of an Online Education Program on Counselors' Knowledge and Attitudes about Near-Death Experiences
An estimated 15 million people in the US have had a near‐death experience (NDE), an experience of usually lucid consciousness during a close brush with death. Following an NDE, experiencers (NDErs) sometimes feel challenged and seek counseling to integrate the experience into their subsequent lives. They have reported psychologically harmful experiences disclosing their NDEs to healthcare professionals, including counselors. Counselors' knowledge and attitude about NDEs appear to be critical variables in their ability to uphold the ethical imperative to do no harm to clients. The recent development of a psychometrically sound instrument to assess these variables, coupled with online availability of a three-part NDE educational program for health professionals, made possible for the first time a large‐scale pre‐post study of the effect of the program on counselors' knowledge and attitude about NDEs. Participants were 212 licensed professional counselors (LPCs) aged 23 to 71 years old (M = 44.93, SD = 12.69); sex self-identified as 12.3% male, 87.3% female, and .5% other; racially/ethnically self-identified as 84% White and 17% non-White and as 6.6% Latino-Hispanic and 92.5% non-Latino/Hispanic; and representing four regions of the US. Results revealed that, compared to control group, composed of LPCs who completed topically unrelated online programs (n …
Date:
May 2017
Creator:
Loseu, Saharnaz
System:
The UNT Digital Library
Carbon-13-carbon-13 Coupling Constants in Fluorene and O-Methylbenzene Derivatives
A model system to calculate single-path coupling constant was devised to see if the couplings are additive in a system which has a dual-pathway. The system chosen was o-methyl-13C-benzoic acid. Because of anomalies in the data, the series was extended. Hybridization of the label appeared to have relatively little effect, and the conformation of the substituents very important.
Date:
August 1977
Creator:
Kattner, Richard M.
System:
The UNT Digital Library
The Mechanism of Formation and Lifetimes of Halogenated Ketenes
The investigation presented here is in two parts: a mechanistic study of the triethylamine dehydrohalogenation of ac-haloacid halides to form halogenated ketenes and a study of steric influence upon ketene lifetimes. The first part of this research deals with the mechanism of the dehydrohalogenation reaction. Two acid halides, isobutyryl chloride and a-chloropropionyl chloride, appeared to represent two mechanistic extremes for this reaction with triethylamine. Isobutyryl chloride reacted with triethylamine to form an acylammonium salt while a-chloropropionyl chloride produced the enolate salt. These salts were detected in chloroform solution by both nuclear magnetic resonance spectra and infrared spectra. The results of the investigation into the mechanism of dehydrohalogenation and ketene lifetime were complemented by CNDO/2 calculations of the acid halides and ketenes studied. It was concluded that the mechanism of dehydrohalogenation of acid halides involves a complex series of equilibria,and it has become increasingly apparent that halogenated ketenes are produced through the acylammonium salt. The enolate salt appears to be a dead end in the reaction to form ketenes. It was also demonstrated that increasing steric bulk has a stabilizing effect on ketene lifetimes.
Date:
August 1974
Creator:
Scherubel, Gary
System:
The UNT Digital Library