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Metabolism of Methylglyoxal by Scenedesmus Quadricauda
The purpose of this study was to investigate the metabolic pathways of methylglyoxal in S. quadricauda. digital.library.unt.edu/ark:/67531/metadc131263/
Metal-Aluminum Oxide Interactions: Effects of Surface Hydroxylation and High Electric Field
Metal and oxide interactions are of broad scientific and technological interest in areas such as heterogeneous catalysis, microelectronics, composite materials, and corrosion. In the real world, such interactions are often complicated by the presence of interfacial impurities and/or high electric fields that may change the thermodynamic and kinetic behaviors of the metal/oxide interfaces. This research includes: (1) the surface hydroxylation effects on the aluminum oxide interactions with copper adlayers, and (2) effects of high electric fields on the interface of thin aluminum oxide films and Ni3Al substrate. X-ray photoelectron spectroscopy (XPS) studies and first principles calculations have been carried out to compare copper adsorption on heavily hydroxylated a- Al2O3(0001) with dehydroxylated surfaces produced by Argon ion sputtering followed by annealing in oxygen. For a heavily hydroxylated surface with OH coverage of 0.47 monolayer (ML), sputter deposition of copper at 300 K results in a maximum Cu(I) coverage of ~0.35 ML, in agreement with theoretical predictions. Maximum Cu(I) coverage at 300 K decreases with decreasing surface hydroxylation. Exposure of a partially dehydroxylated a-Al2O3(0001) surface to either air or 2 Torr water vapor results in recovery of surface hydroxylation, which in turn increases the maximum Cu(I) coverage. The ability of surface hydroxyl groups to enhance copper binding suggests a reason for contradictory experimental results reported in the literature for copper wetting of aluminum oxide. Scanning tunneling microscopy (STM) was used to study the high electric field effects on thermally grown ultrathin Al2O3 and the interface of Al2O3 and Ni3Al substrate. Under STM induced high electric fields, dielectric breakdown of thin Al2O3 occurs at 12.3 } 1.0 MV/cm. At lower electric fields, small voids that are 2-8 A deep are initiated at the oxide/metal interface and grow wider and deeper into the metal substrate, which eventually leads to either physical collapse or dielectric breakdown of the oxide film on top. digital.library.unt.edu/ark:/67531/metadc3039/
Metal Complexes of 2,3-Quinoxalinedithiol
A series of new planar complexes with the dianion of 2,3-quinoxalinedithiol ligand has been prepared. The complexes have been characterized from the study of their analyses, magnetic moment, conductance, polarograms, electron spin resonance spectra, and electronic spectra, and compared with the available data on the corresponding maleonitriledithiolene and toluene-3,4-dithiolene complexes. digital.library.unt.edu/ark:/67531/metadc164322/
Metal (II) Complexes with N-Salicylideneamino Acids
Transition metal complexes derived from Schiff bases have rendered an important contribution to the development of modern coordination chemistry. Various stable compounds have been prepared having synthetic, biological, and physicochemical interest. In particular, complexes of salicylaldimines, B-ketoamines, and closely related ligand systems have been investigated. digital.library.unt.edu/ark:/67531/metadc164341/
Metal Oxide Reactions in Complex Environments: High Electric Fields and Pressures above Ultrahigh Vacuum
Metal oxide reactions at metal oxide surfaces or at metal-metal oxide interfaces are of exceptional significance in areas such as catalysis, micro- and nanoelectronics, chemical sensors, and catalysis. Such reactions are frequently complicated by the presence of high electric fields and/or H2O-containing environments. The focus of this research was to understand (1) the iron oxide growth mechanism on Fe(111) at 300 K and 500 K together with the effect of high electric fields on these iron oxide films, and (2) the growth of alumina films on two faces of Ni3Al single crystal and the interaction of the resulting films with water vapor under non-UHV conditions. These studies were conducted with AES, LEED, and STM. XPS was also employed in the second study. Oxidation of Fe(111) at 300 K resulted in the formation of Fe2O3 and Fe3O4. The substrate is uniformly covered with an oxide film with relatively small oxide islands, i.e. 5-15 nm in width. At 500 K, Fe3O4 is the predominant oxide phase formed, and the growth of oxide is not uniform, but occurs as large islands (100 - 300 nm in width) interspersed with patches of uncovered substrate. Under the stress of STM induced high electric fields, dielectric breakdown of the iron oxide films formed at 300 K occurs at a critical bias voltage of 3.8 ± 0.5 V at varying field strengths. No reproducible result was obtained from the high field stress studies of the iron oxide formed at 500 K. Ni3Al(110) and Ni3Al(111) were oxidized at 900 K and 300 K, respectively. Annealing at 1100 K was required to order the alumina films in both cases. The results demonstrate that the structure of the 7 Å alumina films on Ni3Al(110) is k-like, which is in good agreement with the DFT calculations. Al2O3/Ni3Al(111) (γ'-phase) and Al2O3/Ni3Al(110) (κ-phase) films undergo drastic reorganization and reconstruction, and the eventual loss of all long-range order upon exposure to H2O pressure > 10-5 Torr. Al2O3/Ni3Al(110) film is significantly more sensitive to H2O vapor than the Al2O3/Ni3Al(111) film, and this may be due to the incommensurate nature of the oxide/Ni3Al(110) interface. STM measurements indicate that this effect is pressure- rather than exposure- dependent, and that the oxide instability is initiated at the oxide surface, rather than at the oxide/metal interface. The effect is not associated with formation of a surface hydroxide, yet is specific to H2O (similar O2 exposures have no effect). digital.library.unt.edu/ark:/67531/metadc4843/
Metallization and Modification of Low-k Dielectric Materials
Aluminum was deposited onto both Teflon AF and Parylene AF surfaces by chemical vapor deposition of trimethylaluminum. This work shows that similar thin film (100 Angstroms) aluminum oxide adlayers form on both polymers at the low temperature dosing conditions used in the studies. Upon anneal to room temperature and above, defluorination of the polymer surfaces increased and resulted in fluorinated aluminum oxide adlayers; the adlayers were thermally stable to the highest temperatures tested (600 K). Angle-resolved spectra showed higher levels of fluorination toward the polymer/adlayer interface region. Copper films were also deposited at low temperature onto Teflon AF using a copper hexafluoroacetylacetonate-cyclooctadiene precursor. Annealing up to 600 K resulted in the loss of precursor ligands and a shift to metallic copper. As with aluminum adlayers, some polymer defluorination and resulting metal (copper) fluoride was detected. Parylene AF and polystyrene films surfaces were modified by directly dosing with water vapor passed across a hot tungsten filament. Oxygen incorporation into polystyrene occurred exclusively at aromatic carbon sites, whereas oxygen incorporation into parylene occurred in both aromatic and aliphatic sites. Oxygen x-ray photoelectron spectra of the modified polymers were comparable, indicating that similar reactions occurred. The surface oxygenation of parylene allowed enhanced reactivity toward aluminum chemical vapor deposition. Silicon-carbon (Si-Cx) films were formed by electron beam bombardment of trimethylvinylsilane films which were adsorbed onto metal substrates at low temperatures in ultra-high vacuum. Oxygen was also added to the films by coadsorbing water before electron beam bombardment; the films were stable to more than 700 K, with increasing silicon-oxygen bond formation at elevated temperatures. Copper metal was sputter deposited in small increments onto non-oxygenated films. X-ray photoelectric spectra show three-dimensional copper growth (rather than layer-by-layer growth), indicating only weak interaction between the copper and underlying films. Annealing at elevated temperatures caused coalescence or growth of the copper islands, with spectra indicating metallic copper rather than copper oxide. digital.library.unt.edu/ark:/67531/metadc9754/
Metals in Chemistry and Biology: Computational Chemistry Studies
Numerous enzymatic reactions are controlled by the chemistry of metallic ions. This dissertation investigates the electronic properties of three transition metal (copper, chromium, and nickel) complexes and describes modeling studies performed on glutathione synthetase. (1) Copper nitrene complexes were computationally characterized, as these complexes have yet to be experimentally isolated. (2) Multireference calculations were carried out on a symmetric C2v chromium dimer derived from the crystal structure of the [(tBu3SiO)Cr(µ-OSitBu3)]2 complex. (3) The T-shaped geometry of a three-coordinate β-diketiminate nickel(I) complex with a CO ligand was compared and contrasted with isoelectronic and isosteric copper(II) complexes. (4) Glutathione synthetase (GS), an enzyme that belongs to the ATP-grasp superfamily, catalyzes the (Mg, ATP)-dependent biosynthesis of glutathione (GSH) from γ-glutamylcysteine and glycine. The free and reactant forms of human GS (wild-type and glycine mutants) were modeled computationally by employing molecular dynamics simulations, as these currently have not been structurally characterized. digital.library.unt.edu/ark:/67531/metadc3678/
Metamodeling-based Fast Optimization of Nanoscale Ams-socs
Modern consumer electronic systems are mostly based on analog and digital circuits and are designed as analog/mixed-signal systems on chip (AMS-SoCs). the integration of analog and digital circuits on the same die makes the system cost effective. in AMS-SoCs, analog and mixed-signal portions have not traditionally received much attention due to their complexity. As the fabrication technology advances, the simulation times for AMS-SoC circuits become more complex and take significant amounts of time. the time allocated for the circuit design and optimization creates a need to reduce the simulation time. the time constraints placed on designers are imposed by the ever-shortening time to market and non-recurrent cost of the chip. This dissertation proposes the use of a novel method, called metamodeling, and intelligent optimization algorithms to reduce the design time. Metamodel-based ultra-fast design flows are proposed and investigated. Metamodel creation is a one time process and relies on fast sampling through accurate parasitic-aware simulations. One of the targets of this dissertation is to minimize the sample size while retaining the accuracy of the model. in order to achieve this goal, different statistical sampling techniques are explored and applied to various AMS-SoC circuits. Also, different metamodel functions are explored for their accuracy and application to AMS-SoCs. Several different optimization algorithms are compared for global optimization accuracy and convergence. Three different AMS circuits, ring oscillator, inductor-capacitor voltage-controlled oscillator (LC-VCO) and phase locked loop (PLL) that are present in many AMS-SoC are used in this study for design flow application. Metamodels created in this dissertation provide accuracy with an error of less than 2% from the physical layout simulations. After optimal sampling investigation, metamodel functions and optimization algorithms are ranked in terms of speed and accuracy. Experimental results show that the proposed design flow provides roughly 5,000x speedup over conventional design flows. Thus, this dissertation greatly advances the state-of-the-art in mixed-signal design and will assist towards making consumer electronics cheaper and affordable. digital.library.unt.edu/ark:/67531/metadc115081/
Metamorphosis: William Faulkner's Incorporation of Short Stories into Longer Narratives
This study analyzes these stories in their original and later forms, both to discover the types of changes Faulkner made and to determine whether or not he followed any pattern in the revisions. digital.library.unt.edu/ark:/67531/metadc108116/
“A Metaphor for the Impossibility of Togetherness”: Expansion Processes in Gubaidulina’s First String Quartet
This thesis illustrates how I hear processes of expansion organizing musical materials in the First String Quartet. By employing a flexible approach to expansion and developing models of wedge and additive expansions beyond the bounds of specific voice-leading or rhythmic augmentation procedures, expansion processes can be understood in each of the varied episodes of the quartet. Gubaidulina’s use of expansion processes, embodied organically in pitch, rhythm, form, and physical space, unifies the episodic materials of the First String Quartet and provides an inevitable conclusion to the work’s loose narrative. digital.library.unt.edu/ark:/67531/metadc149671/
Metaphors, Myths, and Archetypes: Equal Paradigmatic Functions in Human Cognition?
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The overview of contributions to metaphor theory in Chapters 1 and 2, examined in reference to recent scholarship, suggests that the current theory of metaphor derives from long-standing traditions that regard metaphor as a crucial process of cognition. This overview calls to attention the necessity of a closer inspection of previous theories of metaphor. Chapter 3 takes initial steps in synthesizing views of domains of inquiry into cognitive processes of the human mind. It draws from cognitive models developed in linguistics and anthropology, taking into account hypotheses put forth by psychologists like Jung. It sets the stage for an analysis that intends to further understanding of how the East-West dichotomy guides, influences, and expresses cognitive processes. Although linguist George Lakoff denies the existence of a connection between metaphors, myths, and archetypes, Chapter 3 illustrates the possibility of a relationship among these phenomena. By synthesizing theoretical approaches, Chapter 3 initiates the development of a model suitable for the analysis of the East-West dichotomy as exercised in Chapter 4. As purely emergent from bodily experience, however, neither the concept of the East nor the concept of the West can be understood completely. There exist cultural experiences that may, depending on historical and social context, override bodily experience inclined to favor the East over the West because of the respective connotations of place of birth of the sun and place of death of the sun. This kind of overriding cultural meaning is based on the “typical, frequently recurring and widely shared interpretations of some object, abstract entity, or event evoked in people as a result of similar experiences. To call these meanings ‘cultural meanings' is to imply that a different interpretation is evoked in people with different characteristic experiences. As such, various interpretations of the East-West image-schema exist simultaneously in mutually exclusive or competing forms, as the analysis of Gatsby and the reversal of the values of East and West in the context of colonizing and counter-colonizing attitudes suggests. digital.library.unt.edu/ark:/67531/metadc3284/
A Method for Approximating the Distributed Loads of an Airplane by Sets of Point Loads
This paper gives the derivation of a method for determining the forces to be applied to these points which will simulate the load distributed over all the airplane. digital.library.unt.edu/ark:/67531/metadc107936/
A Method for Calculating Foil Depression Factors
As disc-shaped detectors are one of the primary means of measuring the neutron density, a better solution is desirable if the error due to the depression factor is to be made negligible. In this paper, an attempt is made to solve this problem in the oblate spheroidal co-ordinate system which most nearly describes the disc-shaped detector, so that solutions may be obtained that describe depression factors for detectors of varying thicknesses and radii. digital.library.unt.edu/ark:/67531/metadc130315/
A Method of Analyzing Linear Perspective for Presentation to Junior and Senior High School Students
The general purpose of this study is to develop a series of peep shows, or visual models, which will enable the young student to understand what the laws of perspective are, how they were found, and why his drawings will appear to have three dimensions if he follows the rules. The study is based upon a widely accepted idea--that it is much easier for most people to understand and remember a principle when they can actually see how it works. When rules are merely memorized, one is not assisted by reason, which is essential for useful retention. digital.library.unt.edu/ark:/67531/metadc96896/
A Method of Analyzing Trends in Modern Painting for Presentation to High-School Students
In developing the study, the writer has attempted to devise a method whereby high-school students may gain an understanding of certain trends in modern abstract and non-objective painting. digital.library.unt.edu/ark:/67531/metadc75684/
Methodological Issues in Malingering Research: The Use of Simulation Designs
The accurate determination of malingering relies on the use of validated and clinically relevant assessment measures. Simulation design is the most often-used research design to accomplish this. However, its external validity is sometimes questioned. The goal of the thesis was to systematically evaluate these major elements: situation, incentives, and coaching. The situation in simulation studies can vary from relevant (academic failure in a college population) to irrelevant (capital murder) for the samples being studied. Incentives refer to the external motivation given to improve simulators' performance and can be positive (extra credit and monetary reward) or negative (extra time and effort). Finally, coaching refers to whether the participant receives any information on detection strategies that are designed to identify feigners. Using a large undergraduate sample in a factorial design, results indicate that a scenario familiar to the participants generally improved the believability of their responses. Coaching also improved the ability to feign convincingly, while incentive type was not associated with any change in scores. The implications of these findings for future research designs and the connection to practice are discussed. digital.library.unt.edu/ark:/67531/metadc33153/
Methods and Procedures Employed in the Operation of the Centralized System of Athletics in the White Senior High Schools of Dallas, Texas, 1931-1940
The purpose of this study was to record and interpret the methods and procedures employed in the operation of the centralized system of the athletic program in the white senior high schools of Dallas, Texas, for the years 1931 through 1940. digital.library.unt.edu/ark:/67531/metadc75353/
Methods and Procedures in Directing Extra-Curricular Activities
The purpose of this study is to discover and report the best practices of selecting, organizing, and administering the extra-curricular activitiy program in elementary and secondary schools. digital.library.unt.edu/ark:/67531/metadc29864/
Methods of County Financing in Relation to County Government in Texas
This study aims to show the relation of the methods of county financing in Texas to the present form of county government. It argues that the present form of county government in Texas is antiquated and inadequate to meet the requirements of efficient administration of county financing. digital.library.unt.edu/ark:/67531/metadc70251/
Methods Used to Classify Men Students Enrolled in the Physical Education Required Program at Selected Colleges and Universities in Texas
The purpose of this study is 1. to determine methods currently used by institutions surveyed by the study to classify men students enrolled in physical education required programs; 2. To evaluate methods in use by institutions surveyed by the study to classify men students enrolled in physical education required programs. digital.library.unt.edu/ark:/67531/metadc108040/
Metric Half-Spaces
This paper is a study of some of the basic properties of the metric half-space topology, a topology on a set which is derived from a metric on the set. In the first it is found that in a complete inner product space, the metric half-space topology is the same as one defined in terms of linear functionals on the space. In the second it is proven that in Rn the metric half-space topology is the same as the usual metric topology. In the third theorem it is shown that in a certain sense the nature of the metric halfspace topology generated by a norm on the space determines whether the norm is quadratic, that is to say, whether or not there exists an inner product on the space with the property that |x|^2=(x,x) for all x in the space. digital.library.unt.edu/ark:/67531/metadc131510/
Metric Postulates for Plane Geometry
The purpose of this paper is to investigate Saunders MacLane's axioms for plane geometry. The wording of the axioms has been modified; however, the concept suggested by each axiom remains the same. digital.library.unt.edu/ark:/67531/metadc130541/
Metric Spaces
This thesis covers fundamental properties of metric spaces, as well as completeness, compactness, and separability of metric spaces. digital.library.unt.edu/ark:/67531/metadc107938/
Metrical Analysis in Nineteenth-Century English Criticism of Shakespeare
It is the purpose of this study to resurrect and evaluate the most significant items of metrical analyses of Shakespeare's plays. digital.library.unt.edu/ark:/67531/metadc130751/
Metro Environmental: The impact of training HVAC technicians using the SightPros-VirTechs system for remote, wireless, Internet video assistance.
This qualitative study explored the overall impact of training HVAC technicians using the SightPros-VirTechs system for remote, wireless, internet video assistance at a small HVAC company, Metro Environmental. John Thomason, the president/co-owner developed a website and a new SightPros communication tool that allows wireless, one-on-one, just-in-time, high-quality, video-monitored instructions between an expert at one site and a technician at another site. Metro Environmental successfully used the SightPros-VirTechs system to train a new apprentice remotely. The apprentice and expert changed their normal and routine physical activities because the expert worked remotely and the apprentice worked on-site. Within just a few months, the apprentice proved competent enough to go to customer accounts without more experienced technicians nearby. The technicians express excitement about the SightPros communication tool as a way to contact remote experts whenever needed. The customer and business contacts also give good reviews and suggest other benefits. The expert permanently captures the communications so the company can use the saved video for many applications, especially training. The dissertation provides a list of recommendations to trainers/educators for similar applications. digital.library.unt.edu/ark:/67531/metadc12112/
The Mexican Government and Railroad Development, 1824-1876
This thesis analyzed material on Mexican railroad development before 1876 to determine what principles underlay public action in this area. Only significant or recurring concessions concerning connecting Mexico City and Veracruz, transcontinental communication, and tying the United States and Mexico by rail were studied, since they provided the best means of tracing public action over an extended period of time. digital.library.unt.edu/ark:/67531/metadc164034/
Mexico and Mexicans in the Fiction of Steinbeck, Morris, Traven and Porter
The purpose of this study is to investigate what seem to be the principal attitudes of Americans toward Mexico and Mexicans as expressed by four contemporary American authors, and to point out and evaluate salient features in their respective treatment of the subject. digital.library.unt.edu/ark:/67531/metadc130729/
Mexico in the United Nations
The purpose of this investigation is to look at the international organization from the point of view of a small, non-military nation to discover if and how it may be useful to such a nation in carrying out its foreign policy objectives in a bi-polar, nuclear world. digital.library.unt.edu/ark:/67531/metadc131392/
Michael Daugherty's Red Cape Tango: A Comparative Study of the Original Version for Symphony Orchestra and its Transcription for Wind Orchestra, with Four Recitals of Selected Works by Beethoven, Dvorák, Verdi, Bartók and Daugherty
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Michael Daugherty has created his niche in the music world by composing works inspired by icons of American popular culture. Red Cape Tango is the final movement of his Metropolis Symphony, a work inspired by the life and times of the comic book character Superman. This movement in particular deals with the death of the superhero through the use of musical elements, most notably the Latin Sequence of the Mass for the Dead, Dies irae. Daugherty's ingenuity in blending profoundly dark subjects with humor is particularly evident in this work. Death is personified as a temptress and lures Superman through the power of a seductive tango. This study concentrates on Daugherty's compositional style and its impact in musical circles. A transcription for wind orchestra was created by another composer/conductor precisely because of the need to bring such an important work to another medium, thus making it accessible to a wider audience. In addition, this study looks at the changes in instrumentation necessary to create a second, equally formidable version of the work. digital.library.unt.edu/ark:/67531/metadc3079/
Michael Nyman: The Man Who Mistook His Wife for a Hat
Composer Michael Nyman wrote the one-act, minimalist opera The Man Who Mistook His Wife for a Hat, based off the neurological case study written by Oliver Sacks under the same title. The opera is about a professional singer and professor whom suffers from visual agnosia. In chapter 1, the plot and history of the opera are discussed. Chapter 2 places The Man Who Mistook His Wife for a Hat alongside a selection of minimalist operas from Philip Glass and John Adams. Chapter 3 contains a history of the Fluxus art movement and shows where Fluxus-like examples appear in the opera. Chapter 4 includes Nyman's usage of minimalism, vocal congruencies, and Robert Schumann as musical elements that convey the drama. digital.library.unt.edu/ark:/67531/metadc6135/
Micro and nano composites composed of a polymer matrix and a metal disperse phase.
Low density polyethylene (LDPE) and Hytrel (a thermoplastic elastomer) were used as polymeric matrices in polymer + metal composites. The concentration of micrometric (Al, Ag and Ni) as well as nanometric particles (Al and Ag) was varied from 0 to 10 %. Composites were prepared by blending followed by injection molding. The resulting samples were analyzed by scanning electron microscopy (SEM) and focused ion beam (FIB) in order to determine their microstructure. Certain mechanical properties of the composites were also determined. Static and dynamic friction was measured. The scratch resistance of the specimens was determined. A study of the wear mechanisms in the samples was performed. The Al micro- and nanoparticles as well as Ni microparticles are well dispersed throughout the material while Ag micro and nanoparticles tend to form agglomerates. Generally the presence of microcomposites affects negatively the mechanical properties. For the nanoparticles, composites with a higher elastic modulus than that of the neat materials are achievable. For both micro- and nanocomposites it is feasible to lower the friction values with respective to the neat polymers. The addition of metal particles to polymers also improves the scratch resistance of the composites, particularly so for microcomposites. The inclusion of Ag and Ni particles causes an increase in the wear loss volume while Al can reduce the wear for both polymeric matrices. digital.library.unt.edu/ark:/67531/metadc5135/
Micro-fabrication of a Mach-Zehnder interferometer combining laser direct writing and fountain pen micropatterning for chemical/biological sensing applications.
This research lays the foundation of a highly simplified maskless micro-fabrication technique which involves incorporation of laser direct writing technique combined with fountain pen based micro-patterning method to fabricate polymer-based Mach-Zehnder interferometer sensor arrays' prototype for chemical/biological sensing applications. The research provides methodology that focuses on maskless technology, allowing the definition and modification of geometric patterns through the programming of computer software, in contrast to the conventional mask-based photolithographic approach, in which a photomask must be produced before the device is fabricated. The finished waveguide sensors are evaluated on the basis of their performance as general interferometers. The waveguide developed using the fountain pen-based micro-patterning system is compared with the waveguide developed using the current technique of spin coating method for patterning of upper cladding of the waveguide. The resulting output power profile of the waveguides is generated to confirm their functionality as general interferometers. The results obtained are used to confirm the functionality of the simplified micro-fabrication technique for fabricating integrated optical polymer-based sensors and sensor arrays for chemical/biological sensing applications. digital.library.unt.edu/ark:/67531/metadc10989/
Microbial Activity in "Overland Flow" Industrial Waste Treatment
One of the major problems of modern industries concerns the disposal of waste materials without the concomitant pollution of the environment. Several food and wood products industries have solved this problem by using the "overland flow" method of waste treatment. The research described in this paper was undertaken to ascertain the fact that the waste purification occurring on the disposal field is the result of microbial activities in the soil, and to study the transformations taking place. digital.library.unt.edu/ark:/67531/metadc131129/
A Microbial Survey of Raw Ingredients Used in Finished Products at Kraft Foods Company, Garland, Texas
The purpose of this investigation is to determine through routine checks the number of organisms present in the various raw ingredients used for the preparation of foods. The problem has consisted of, first, a determination of the total bacterial population by numbers; second, a determination of the incidence of colon bacteria in the samples examined; third, a determination of the presence of yeasts and molds; and fourth, an attempt to utilize this information obtained in judging the methods of handling the raw ingredients before they are used in the processing of foods. digital.library.unt.edu/ark:/67531/metadc97028/
Microbial Utilization of a Certain Hydrocarbon Insecticide
This problem includes, first, the isolation and identification of microorganisms which utilized the hydrocarbon insecticide as a sole source of carbon and energy; second, a determination of the effect on plants sprayed with the hydrocarbon medium as compared with the effect on plants sprayed with the hydrocarbon medium containing a good growth of hydrocarbon-utilizers; and third, a determination of the ability of laboratory stock cultures of organisms to utilize or remain alive in the hydrocarbon medium. digital.library.unt.edu/ark:/67531/metadc130266/
Microbiotic Cycles in Lake Hefner
The purposes of this paper are 1) to determine the microbiotic cycles which occur in Lake Hefner in order to form a basis for ascertaining the effects of future additions of evaporation control chemicals on the biological life of this reservoir, and 2) to make a generalization as to the microbiotic cycles which might occur in Southwestern reservoirs. digital.library.unt.edu/ark:/67531/metadc130654/
Microfarms
This study describes the role of rural women and their importance in the success of microfarm projects. Microfarm cultivators can increase their income levels through trade of agricultural products. By adopting self-sustaining methods, the cultivator saves money and does not need to rely as much on goods and services from outside resources to increase food production efficiencies in microfarms. This goal can be reached in part through careful planning and construction of the microfarm facility. In addition, in developing phases of the microfarm, the external resources may possibly be a mechanism to increase expansion and knowledge. Microfarms are an important option for the third world countries and poor people worldwide. digital.library.unt.edu/ark:/67531/metadc4607/
Microflora Found in a Selected Group of Food Products Enclosed in a Protective Wrapper
The purposes of this study are, first, to determine relative numbers and predominant types of bacterial organisms in the various food products studied; second, to evaluate the efficiency of the paper coverings of these foods; and third, to determine whether these products are potential sources of food poisoning. digital.library.unt.edu/ark:/67531/metadc96850/
Microflora of Frozen Fruits and Vegetables Dispensed from Grocery Stores in Denton, Texas
This investigation was carried out in order to determine whether or not blanching and freezing tends to reduce the incidence of bacteria, particularly those of the coliform group, and also the yeasts and molds. digital.library.unt.edu/ark:/67531/metadc83405/
Microorganisms Associated with a Spray Irrigation System
The area of research for this thesis concerns the role played by microorganisms in the process of organic breakdown of waste effluent. Although considerable research has been done since the early 1950's, little consideration has been given to the role of the microorganisms in this type of waste water purification. digital.library.unt.edu/ark:/67531/metadc131158/
Microsatellite-based genetic profiling for the management of wild and captive flamingo populations.
Flamingo species generate tremendous interest whether they are small captive groups or wild populations numbering in the thousands. Genetic pedigrees are invaluable for maintaining maximum genetic diversity in captive, as well as wild, populations. However, presently there is a general lack of genetic data for flamingo populations. Microsatellites are loci composed of 2-6 base pair tandem repeats, scattered throughout higher eukaryotic genomes, often exhibiting high levels of polymorphism and heterozygosity. These loci are thus important genetic markers for identity, parentage and population studies. Here, six microsatellite loci were isolated from a microsatellite-enriched Caribbean flamingo partial genomic library. Two are compound complex repeats and four are perfect trinucleotide repeats. Each locus was amplified from Caribbean, African greater, Chilean and lesser flamingo genomic DNAs. Heterozygosity frequencies were calculated for Caribbean (range 0.12-0.90) and African greater flamingos (range 0.23-0.94) loci. All six microsatellite loci were found to be in Hardy-Weinberg equilibrium and linkage disequilibrium analyses did not suggest linkage for any pair of two greater flamingo subspecies (African and Caribbean) loci. At least five of the loci also exhibit polymorphism in Chilean and lesser flamingos, but due to small sample numbers, relevant allele/heterozygosity frequency calculations could not be estimated. Nucleotide sequence comparisons of the amplicons derived from the four flamingo groups reveal a high level of sequence conservation at all loci. Although small sample numbers again limit the data for lesser flamingos and to some degree for the Chilean birds, the sequences of the two greater flamingo subspecies were identical and the number of nonconserved nucleotides appears to be higher for lesser/greater comparisons than for Chilean/greater comparisons. This is consistent with Chilean flamingos being a different species within the same genus as the greater flamingos, while lesser flamingos belong to a separate genus. Parentage analyses on suggested African greater flamingo family groups from Disney's Animal Kingdom's collection were performed using microsatellite data. Results confirmed many suggested family groups but in other cases one or more of the suggested parents were clearly excluded. The six microsatellite loci isolated provide a new population management tool useful for both wild and captive flamingo populations. digital.library.unt.edu/ark:/67531/metadc4957/
Microscopic Foundations of Thermodynamics and Generalized Statistical Ensembles
This dissertation aims at addressing two important theoretical questions which are still debated in the statistical mechanical community. The first question has to do with the outstanding problem of how to reconcile time-reversal asymmetric macroscopic laws with the time-reversal symmetric laws of microscopic dynamics. This problem is addressed by developing a novel mechanical approach inspired by the work of Helmholtz on monocyclic systems and the Heat Theorem, i.e., the Helmholtz Theorem. By following a line of investigation initiated by Boltzmann, a Generalized Helmholtz Theorem is stated and proved. This theorem provides us with a good microscopic analogue of thermodynamic entropy. This is the volume entropy, namely the logarithm of the volume of phase space enclosed by the constant energy hyper-surface. By using quantum mechanics only, it is shown that such entropy can only increase. This can be seen as a novel rigorous proof of the Second Law of Thermodynamics that sheds new light onto the arrow of time problem. The volume entropy behaves in a thermodynamic-like way independent of the number of degrees of freedom of the system, indicating that a whole thermodynamic-like world exists at the microscopic level. It is also shown that breaking of ergodicity leads to microcanonical phase transitions associated with nonanalyticities of volume entropy. The second part of the dissertation deals with the problem of the foundations of generalized ensembles in statistical mechanics. The starting point is Boltzmann's work on statistical ensembles and its relation with the Heat Theorem. We first focus on the nonextensive thermostatistics of Tsallis and the associated deformed exponential ensembles. These ensembles are analyzed in detail and proved (a) to comply with the requirements posed by the Heat Theorem, and (b) to interpolate between canonical and microcanonical ensembles. Further they are showed to describe finite systems in contact with finite heat baths. Their mechanical and information-theoretic foundation, are highlighted. Finally, a wide class of generalized ensembles is introduced, all of which reproduce the Heat Theorem. This class, named the class of dual orthodes, contains microcanonical, canonical, Tsallis and Gaussian ensembles as special cases. digital.library.unt.edu/ark:/67531/metadc6128/
Microstructure and Electronic Structures of Er-Doped Si Nano-particles Synthesized by Vapor Phase Pyrolysis
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Si nanoparticles are new prospective optoelectronic materials. Unlike bulk Si cry-stals, Si nanoparticles display intriguing room-temperature photoluminescence. A major challenge in the fabrication of Si nanoparticles is the control of their size distribution. The rare-earth element Er has unique photo emission properties, including low pumping power, and a temperature independent, sharp spectrum. The emission wavelength matches the transmission window of optical fibers used in the telecommunications industry. Therefore, the study of Er-doped Si nanoparticles may have practical significance. The goals of the research described in this dissertation are to investigate vapor phase pyrolysis methods and to characterize the microstructure and associated defects, particles size distributions and photoluminescence efficiencies of doped and undoped Si nanoparticles using analytical transmission electron microscopy, high resolution electron microscopy, and optical spectroscopy. Er-doped and undoped Si nanoparticles were synthesized via vapor-phase pyrolysis of disilane at Texas Christian University. To achieve monodisperse size distributions, a process with fast nucleation and slow growth was employed. Disilane was diluted to 0.48% with helium. A horizontal pyrolysis oven was maintained at a temperature of 1000 °C. The oven length was varied from 1.5 cm to 6.0 cm to investigate the influence of oven length on the properties of the nanoparticles. The Si nanoparticles were collected in ethylene-glycol. The doped and undoped Si nanoparticles have a Si diamond cubic crystal structure. Neither Er precipitation, Er oxides or Er silicides were detected in any of the samples. The Er dopant concentration was about 2 atom% for doped samples from the 3.0 and 6.0 cm ovens as determined by quantitative analysis using X-ray energy dispersive spectroscopy. The average Si nanoparticle size increases from 11.3 to 15.2 nm in the doped samples and from 11.1 to 15.7 nm in the undoped samples as the oven length increases from 1.5 to 6.0 cm. HREM data show that average Si nanocrystallite size varies from 6.4 to 3.3 to 5.9 nm in the doped samples, and from 7.5 to 12.2 nm in the undoped samples as the oven length increases. Room-temperature Er photoluminescence has been detected near 1.54 :m from all doped samples. Saturation of the Er photoluminescence intensity at large emission power and the monotonic decrease of the intensity as a function of the emission wavelength in the doped sample from the 3.0 cm oven suggest that a carrier-mediated energy transfer process occurs in the Er-doped Si nanoparticles. It is the first time to successfully fabricate and investigate Er-doped Si nanoparticles. digital.library.unt.edu/ark:/67531/metadc2476/
Microstructure Evolution in Laser Deposited Nickel-Titanium-Carbon in situ Metal Matrix Composite
Ni/TiC metal matrix composites have been processed using the laser engineered net shaping (LENS) process. As nickel does not form an equilibrium carbide phase, addition of a strong carbide former in the form of titanium reinforces the nickel matrix resulting in a promising hybrid material for both surface engineering as well as high temperature structural applications. Changing the relative amounts of titanium and carbon in the nickel matrix, relatively low volume fraction of refined homogeneously distributed carbide precipitates, formation of in-situ carbide precipitates and the microstructural changes are investigated. The composites have been characterized in detail using x-ray diffraction, scanning electron microscopy (including energy dispersive spectroscopy (XEDS) mapping and electron backscatter diffraction (EBSD)), Auger electron spectroscopy, and transmission (including high resolution) electron microscopy. Both primary and eutectic titanium carbides, observed in this composite, exhibited the fcc-TiC structure (NaCl-type). Details of the orientation relationship between Ni and TiC have been studied using SEM-EBSD and high resolution TEM. The results of micro-hardness and tribology tests indicate that these composites have a relatively high hardness and a steady-state friction coefficient of ~0.5, both of which are improvements in comparison to LENS deposited pure Ni. digital.library.unt.edu/ark:/67531/metadc33154/
Microwave-Assisted Synthesis, Characterization, and Photophysical Properties of New Rhenium(I) Pyrazolyl-Triazine Complexes
The reaction of the chelating ligand 4-[4,6-bis(3,5-dimethyl-1H-pyrazol-1-yl)-1,3,5-triazin-2-yl]-N,N-diethyl-benzenamine, L, with pentacarbonylchlororhenium by conventional heating method produces the complexes fac-[ReL(CO)3Cl2] and fac-[Re2L(CO)6Cl2] in a period of 48 hours. The use of microwaves as the source of heat and the increase in the equivalents of one of the reactants leads to a more selective reaction and also decreases the reaction time to 1 hour. After proper purification, the photophysical properties of fac-[ReL(CO)3Cl] were analyzed. The solid-state photoluminescence analysis showed an emission band at 628 nm independent of temperature. However, in the solution studies, the emission band shifted from 550 nm in frozen media to 610 nm when the matrix became fluid. These results confirm that this complex possess a phenomenon known as rigidochromism. digital.library.unt.edu/ark:/67531/metadc28473/
Microwave Cavity Method for Measuring Plasma Properties
This discussion is concerned primarily with communications blackout during spacecraft entry into a planetary atmosphere. The gas in the shock layer, between shock wave and vehicle surface, ionizes from the intense heating which takes place in the bow shock wave and a viscous region of high gas enthalpy. This ionization may persist throughout the subsequent flow over the vehicle and into the wake, thus completely engulfing the vehicle and its communications elements. The problem will be to simulate a plasma model that will be of interest for hypervelocity reentry vehicles and to provide meaningful expressions for the various plasma parameters of interest (electron density, electron temperature, collision frequency, etc.) in terms of the microwave measurables (amplitude, phase shifts, frequency shifts, polarization, etc.) digital.library.unt.edu/ark:/67531/metadc163950/
Microwave Cavity Test for Superconductivity
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The first part of this paper describes the Meissner effect in superconductors which serves as the most definitive evidence for superconductivity. It is shown that the microwave perturbation technique may be used to demonstrate this effect. By measuring the changes of resonant frequency and inverse quality factor Q of a microwave cavity with a small volume of sample loading, the Meissner effect can be shown by using the Slater perturbation equation. The experimental system is described with details and the basic principle of each component discussed. The second part of this work describes the technique employed to do the actual measurements. The experiments were conducted on samples of Gallium Arsenide (GaAs) and lead zirconate titanate (PZT) to look for the possible high temperature superconductivity properties. Results of these experiments are presented and discussed. Conclusion and suggestions to future exploration are made. digital.library.unt.edu/ark:/67531/metadc2996/
A Microwave Spectrometer for Narrow-line Electron Spin Resonance Studies
This thesis explores the basic theory, design and construction of electron spin resonance spectrometer. digital.library.unt.edu/ark:/67531/metadc163881/
Middle Men: Establishing Non-Anglo Masculinity in Southwestern Literature
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By examining southwestern masculinity from three separate lenses of cultural experience, Mexican American, Native American and female, this thesis aims to acknowledge the blending of masculinities that is taking place in both the fictitious and factual southwest. Long gone are the days when the cowboys chased down the savage Indians or the Mexican bandits. Southwestern literature now focuses on how these different cultures and traditions can re-construct their masculinities in a way that will be beneficial to all. The southwest is a land of borders and liminal spaces between the United States and Mexico, between brown and white, legal and illegal. All of these borders converge here to create the last American frontier. These converging borders also encompass converging traditions, cultures, and genders. By blending the cowboy, the macho, and the warrior, perhaps these Southwestern writers can construct a liminal masculinity more representative of the southwest itself. digital.library.unt.edu/ark:/67531/metadc4259/
Middle School Students in Virtual Learning Environments
This ethnographic study examined middle school students engaged in a virtual learning environment used in concert with face-to-face instruction in order to complete a collaborative research project. Thirty-eight students from three eighth grade classes participated in this study where data were collected through observation of student work within the virtual learning environment, an online survey, and focus group sessions with students involved in the project. Results indicated students found the virtual learning environment to be valuable as a platform to complete a collaborative research assignment because of portability, ease of use, and organization. Embedded resources within the environment were helpful because of the convenience. Other people, including peers and teachers, were the preferred source of help when problems navigating the environment or finding information arose. Students communicated within the virtual learning environment as a social outlet, a way to check in, and a means to offer content related comments. Ideally the study's findings will give insight into student experiences in a virtual learning environment in order to help educators design more effective learning experiences and incorporate useful supports within such environments. digital.library.unt.edu/ark:/67531/metadc30529/