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Presentation Options for Sculpture (open access)

Presentation Options for Sculpture

The act of putting anything on a base isolates it and makes it seem more precious. The base separates the viewer from the sculpture and affects the relationship between the sculpture and viewer. The problem for me was to remove the base and experiment with the possibilities now opened to my work. The purpose of this study was to explore the presentation potentials of sculpture freed from the constraints of the plinth.
Date: May 1992
Creator: Morrow, Elizabeth Lynn
System: The UNT Digital Library
As Thought is to Speech (open access)

As Thought is to Speech

This problem tries to bring together a comprehensive array of themes. There has been a duality between painterly techniques, recognizable images and disjunctive imagery. The subtractive painting technique used has created smooth transitions between images and made these hybrid realities more convincing.
Date: May 1992
Creator: Miller, Susan
System: The UNT Digital Library
An Illustrative Documentation of Afro-American Vernacular Dancers From the 1900's to 1945 (open access)

An Illustrative Documentation of Afro-American Vernacular Dancers From the 1900's to 1945

It was impossible to document all of the important dancers of the era; however, certain individuals were notably exceptional. The purpose of this study was to document and illustrate some of those dancers who impacted and influenced the development of American vernacular dance during the early twentieth century through the mid-1940's. The individuals chosen were as follows: Dewey "Pigmeat" Markham, John Bubbles, Bill Robinson, Earl "Snakeships" Tucker, James Walker and Charles Green (Chuck and Chuckles), Katherine Dunham, Honi Coles and Cholly Akins (Coles and Akins) Josephine Baker, The Derry Brothers (Ananias, Jimmy and Warren), Eddie Rector, Willa Mae Ricker and Leon James. Emphasis was concentrated on capturing an accurate likeness of the individuals as well as on establishing a specific mood. Since all of the above-mentioned individuals were dancers, a special effort was made to recreate the lighting and aura of the stage.
Date: May 1992
Creator: Woosley, Brigitte J.
System: The UNT Digital Library
Temperature history and microstructure of alumina (open access)

Temperature history and microstructure of alumina

A simple process for the attainment of fully dense and improved microstructure for Al{sub 2}O{sub 3} ceramics has been developed. Pure, narrow size distribution, submicron powder is used. Homogenization heat treatment of Al{sub 2}O{sub 3} powder compacts at 800{degree}C for 50 hours produces more uniform pore structure and higher green strength. Pore size distribution becomes narrower. Near fully dense, fine-grained (< 1.2{mu}m) and uniform grain size-distribution, undoped Al{sub 2}O{sub 3} ceramics can be produced using a high quality powder, a high-pressure cold isostatic forming method, and a two-step sintering technique. Improvements in the microstructure of Al{sub 2}O{sub 3} ceramics homogenized at 800{degree}C/50 h include a smaller pore size and a more uniform pore size distribution. Prevention of differential densification in the early stages and delay of pore channel closure to the later stages of sintering are believed to be the primary mechanisms for the microstructure improvement in two-step sintering. Two-step sintering is an alternate way to improve the microstructure of Al{sub 2}O{sub 3} ceramics compared to fast firing or MgO doping. When a homogenization heat treatment and the fast firing are combined, the final density is higher than from fast firing alone. However, the two-step sintering technique is simple and …
Date: May 1, 1992
Creator: Lin, Jiang Tsair
System: The UNT Digital Library
An analysis of multiple particle settling for LMR backup shutdown systems (open access)

An analysis of multiple particle settling for LMR backup shutdown systems

Backup shutdown systems proposed for future LMRs may employ discreet absorber particles to provide the negative reactivity insertion. When actuated, these systems release a dense packing of particles from an out-of-core region to settle into an in-core region. The multiple particle settling behavior is analyzed by the method of continuity waves. This method provides predictions of the dynamic response of the system including the average particle velocity and volume fraction of particles vs. time. Although hindered settling problems have been previously analyzed using continuity wave theory, this application represents an extension of the theory to conditions of unrestrained settling. Typical cases are analyzed and numerical results are calculated based on a semi-empirical drift-flux model. For 1/4-inch diameter boron-carbide particles in hot liquid sodium, the unrestrained settling problem assumes a steady-state solution when the average volume fraction of particles is 0.295 and the average particle velocity is 26.0 cm/s.
Date: May 1, 1992
Creator: Brock, R. W.
System: The UNT Digital Library
Reaction dynamics and photochemistry of divalent systems (open access)

Reaction dynamics and photochemistry of divalent systems

Results are presented of molecular beam studies of bimolecular and unimolecular reactions of Ba. Chapter 1 discusses the reaction Ba + NO{sub 2}. Formation of the dominant BaO({sup 1}{Sigma}) + NO products resulted primarily from decay of long-lived Ba{sup +}NO{sub 2}{sup {minus}} collision complexes. Secondary mechanisms led to formation of forward scattered, internally excited BaO, and BaNO + O. D{sub o}(Ba-NO) = 65{plus_minus}20 kcal/mol. Reactions of ground state and electronically excited Ba with water and alcohols are examined in Chapter 2. Reaction of Ba({sup 1}S) + H{sup 2}O led to BaO + H{sub 2}, whereas excited state Ba({sup 1}D) + H{sub 2}O reacted to form BaOH + H. Collisions between Ba and CH{sub 3}OH led to BaOCH{sub 3} + H. Radical channels involve H-atom migration and are promoted by excitation of the incident Ba atom. In Chapter 3, reactions of Ba({sup 1}S) with ClO{sub 2}2 and O{sub 3} are discussed. Again, direct and complex mechanisms were observed. Formation of BaCl + O{sub 2} from decomposition of Ba{sup +}ClO{sub 2}{sup {minus}} accounted for 10% of total reaction crass section. Although Ba + O{sub 3} {yields} BaO + 0{sub 2} occurs primarily by direct reaction mechanisms, the secondary channel Ba + 0{sub …
Date: May 1, 1992
Creator: Davis, H. F.
System: The UNT Digital Library
Nucleation and growth in electrodeposition of thin copper films on pyrolytic graphite (open access)

Nucleation and growth in electrodeposition of thin copper films on pyrolytic graphite

Electrodeposition of Cu on graphite electrodes was studied, with emphasis on nucleation. Various ex-situ and in-situ methods were investigated for determining the number density of nuclei. Two direct methods were studied (scanning electron microscopy and scanning tunneling microscopy); indirect determinations included Raman spectroscopy and analysis of potentiostatic current transients. Though some of the techniques correctly predicted the nucleation densities under special conditions, SEM was the most reliable tool. The large scatter in the data necessitated steps to minimize this effect. To electrodeposit Cu on graphite, a nucleation overpotential of 250 mV was measured with cyclic voltammetry; such a large overpotential does not occur on a Pt or on a Cu-covered graphite electrode. The deposition potential is the dominant parameter governing nucleation density. There is a sharp increase in the nucleation density with applied potential. Cu can be deposited on highly oriented pyrolytic graphite only between the nucleation overpotential and the hydrogen evolution potential. To increase the Cu nucleation density, while avoiding excessive H evolution, a double pulse potential technique was used; nucleation densities on the order of 10{sup 10} nuclei/cm{sup 2} were achieved. The use of inhibitors (PVA, benzotriazole) was also investigated. Deposition on conducting polymer electrodes was also studied; …
Date: May 1, 1992
Creator: Kinaci, F. S. & Muller, R. H.
System: The UNT Digital Library
Separation of compounds with multiple -OH groups from dilute aqueous solutions via complexation with organoboronate (open access)

Separation of compounds with multiple -OH groups from dilute aqueous solutions via complexation with organoboronate

The complexing extractant agent investigated in this work is 3-nitrophenylboronic acid (NPBA) in its anionic form (NPB). NPBA and Aliquat 336 (quaternary amine) is dissolved in 2-ethyl-l-hexanol, and the extractant is contacted with aq. NaOH. Solutes investigated were 1,2-propanediol, glycerol, fructose, sorbitol and lactic acid. Batch extraction experiments were performed at 25{degree}C. Partition coefficients, distribution ratios and loadings are reported for varying concentrations of solute and NPB. All solutes complexed with NPB{sup {minus}}, with all complexes containing only one NPB{sup {minus}} per complex. The 1:1 complexation constants for the solutes glycerol, fructose and sorbitol follow trends similar to complexation with B(OH){sub 4}{sup {minus}} (aq.), i.e. the complexation constants increase with increasing number of {minus}OH groups available for complexation. Assumption of 1:1 complex is not valid for 1, 2-propanediol, which showed overloading (more than one mole of solute complexed to one mole NPB{sup {minus}}) at higher concentrations. The {minus}OH group on the NPB{sup {minus}} which is left uncomplexed after one solute molecule had bound to the other two {minus}OH groups may be responsible for the overloading. Overloading is also observed in extraction of tactic acid, but through a different mechanism. It was found that TOMA{sup +} can extract lactic acid to …
Date: May 1, 1992
Creator: Chow, Tina Kuo Fung
System: The UNT Digital Library
The effect of low Au concentrations on the properties of eutectic Sn/Pb (open access)

The effect of low Au concentrations on the properties of eutectic Sn/Pb

This study was of the effects moderately low Au concentrations ({le} 10 wt%) have on the mechanical properties and microstructure of an eutectic Sn/Pb alloy. Vibration (60--90 Hz swept sine wave for 30 hours) and thermal cycling (0--110C for 1450 cycles) reliability tests were performed on fine pitch leaded chip carriers using eutectic Sn/Pb solder on PCBs (printed circuit boards) with 0, 5, 10, 20, and 50{mu}in nominal Au thicknesses. Testing was also performed on double shear creep specimens consisting of arrays of regular pitch joints. There was a dramatic increase in the number of joints containing voids with increasing Au concentration, an effect more pronounced in the creep joints than in the reliability joints. These voids tended to coalesce and grow during rework simulation of the reliability joints. AuSn{sub 4} intermetallics present in toe of 4.8 wt% (50 {mu}in) Au vibration joints rotated from initial vertical perpendicular to surface of PCB metallization, solidification positions to roughly horizontal (parallel to plating surface) orientations during rework simulation and during aging of the parts. The AuSn{sub 4} intermetallics in the toe of the 4.8 wt% (50{mu}in) Au reflowed joints also rotated after vibration testing. No joint failures were observed in either vibration …
Date: May 1, 1992
Creator: Kramer, P. A.
System: The UNT Digital Library
Sol-gel derived ceramic electrolyte films on porous substrates (open access)

Sol-gel derived ceramic electrolyte films on porous substrates

A process for the deposition of sol-gel derived thin films on porous substrates has been developed; such films should be useful for solid oxide fuel cells and related applications. Yttria-stabilized zirconia films have been formed from metal alkoxide starting solutions. Dense films have been deposited on metal substrates and ceramic substrates, both dense and porous, through dip-coating and spin-coating techniques, followed by a heat treatment in air. X-ray diffraction has been used to determine the crystalline phases formed and the extent of reactions with various substrates which may be encountered in gas/gas devices. Surface coatings have been successfully applied to porous substrates through the control of substrate pore size and deposition parameters. Wetting of the substrate pores by the coating solution is discussed, and conditions are defined for which films can be deposited over the pores without filling the interiors of the pores. Shrinkage cracking was encountered in films thicker than a critical value, which depended on the sol-gel process parameters and on the substrate characteristics. Local discontinuities were also observed in films which were thinner than a critical value which depended on the substrate pore size. A theoretical discussion of cracking mechanisms is presented for both types of cracking, …
Date: May 1, 1992
Creator: Kueper, T. W.
System: The UNT Digital Library
Trapping the M{sub 1} and M{sub 2} substrates of bacteriorhodopsin for electron diffraction studies (open access)

Trapping the M{sub 1} and M{sub 2} substrates of bacteriorhodopsin for electron diffraction studies

Visible and Fourier transform infrared (FTIR) absorption spectroscopies are used to observe protein conformational changes occuring during the bacteriorhodopsin photocycle. Spectroscopic measurements which define the conditions under which bacteriorhodopsin can be isolated and trapped in two distinct substates of the m intermediate of the photocycle, M{sub 1}, and M{sub 2}, are described. A protocol that can be used for high-resolution electron diffraction studies is presented that will trap glucose-embedded purple membrane in the M{sub 1}and M{sub 2} substates at greater than 90% concentration. It was discovered that glucose alone does not provide a fully hydrated environment for bacteriorhodopsin. Equilibration of glucose-embedded samples at high humidity can result in a physical state that is demonstrably closer to the native, fully hydrated state. An extension of the C-T Model of bacteriorhodopsin functionality (Fodor et al., 1988; Mathies et al., 1991) is proposed based on FTIR results and guided by published spectra from resonance Raman and FTIR work. 105 refs.
Date: May 1, 1992
Creator: Perkins, G. A.
System: The UNT Digital Library
A Cloudy Quark Bag Model of S, P, and D wave interactions for the coupled channel antikaon-nucleon system (open access)

A Cloudy Quark Bag Model of S, P, and D wave interactions for the coupled channel antikaon-nucleon system

The Cloudy Quark Bag Model is extended from S-wave to P- and D-wave. The parameters of the model are determined by K{sup {minus}}p scattering cross section data, K{sup {minus}}p {yields}{Sigma}{pi}{pi}{pi} production data, K{sup {minus}}p threshold branching ratio data, and K{sup {minus}}p {yields}{Lambda}{pi}{pi}{pi} production data. The resonance structure of the {Lambda}(1405), {Sigma}(1385), and {Lambda}(1520) are studied in the model. The shift and width of kaonic hydrogen are calculated using the model.
Date: May 15, 1992
Creator: He, Guangliang
System: The UNT Digital Library
Seismic wave propagation in thinly-layered media with steep reflectors (open access)

Seismic wave propagation in thinly-layered media with steep reflectors

Seismic waves reflected from steep reflectors in the earth`s subsurface spend a significant amount of time travelling more or less horizontally. Therefore, accurate imaging of steep geologic structure requires knowledge of the behavior of these horizontally propagating waves. In particular, the effect of tunneling on seismic waves propagating in thinly-layered media must be understood. I describe a method for modeling seismic waves traveling in thinly-layered media. This method, a frequency-wavenumber finite-difference scheme coupled with the Born approximation, is useful in studying seismic waves reflected from steep geologic structures.
Date: May 1992
Creator: Deng, H. L.
System: The UNT Digital Library
Structural transformation of nickel hydroxide films during anodic oxidation (open access)

Structural transformation of nickel hydroxide films during anodic oxidation

The transformation of anodically formed nickel hydroxide/oxy-hydroxide electrodes has been investigated. A mechanism is proposed for the anodic oxidation reaction, in which the reaction interface between the reduced and oxidized phases of the electrode evolves in a nodular topography that leads to inefficient utilization of the active electrode material. In the proposed nodular transformation model for the anodic oxidation reaction, nickel hydroxide is oxidized to nickel oxy-hydroxide in the region near the metal substrate. Since the nickel oxy-hydroxide is considerably more conductive than the surrounding nickel hydroxide, as further oxidation occurs, nodular features grow rapidly to the film/electrolyte interface. Upon emerging at the electrolyte interface, the reaction boundary between the nickel hydroxide and oxy-hydroxide phases spreads laterally across the film/electrolyte interface, creating an overlayer of nickel oxy-hydroxide and trapping uncharged regions of nickel hydroxide within the film. The nickel oxy-hydroxide overlayer surface facilitates the oxygen evolution side reaction. Scanning tunneling microscopy of the electrode in its charged state revealed evidence of 80 {endash} 100 Angstrom nickel oxy-hydroxide nodules in the nickel hydroxide film. In situ spectroscopic ellipsometer measurements of films held at various constant potentials agree quantitatively with optical models appropriate to the nodular growth and subsequent overgrowth of the …
Date: May 1, 1992
Creator: Crocker, R. W. & Muller, R. H.
System: The UNT Digital Library
A kinetic study of methanol synthesis in a slurry reactor using a CuO/ZnO/Al{sub 2}O{sub 3} catalyst (open access)

A kinetic study of methanol synthesis in a slurry reactor using a CuO/ZnO/Al{sub 2}O{sub 3} catalyst

A kinetic model that describes the methanol production rate over a CuO/ZnO/AI{sub 2}0{sub 3} catalyst (United Catalyst L-951) at typical industrial operating conditions is developed using a slurry reactor. Different experiments are conducted in which the H{sub 2}/(CO+CO{sub 2}) ratio is equal to 2, 1, and 0.5, respectively, while the CO/CO{sub 2} ratio is held constant at 9. At each H{sub 2}/(CO+CO{sub 2}) ratio the space velocity is set at four different values in the range of 3000-13,000 1/hr kg{sub cat}. The effect of H{sub 2}/(CO+CO{sub 2}) ratio and space velocity on methanol production rate, conversions, and product composition is further investigated. The results indicate that the highest methanol production rate can be achieved at H{sub 2}/(CO+CO{sub 2}) ratio of 1 followed by H{sub 2}/(CO+CO{sub 2}) ratio of 0.5 and 2 respectively. The hydrogen and carbon monoxide conversions decrease with increasing space velocity for all H{sub 2}/(CO+CO{sub 2}) ratios tested. Carbon monoxide hydrogenation appears to be the main route to methanol at H{sub 2}/(CO+CO{sub 2}) ratio of 0.5 and 2. On the other hand, carbon dioxide hydrogenation appears to be the main route to methanol at H{sub 2}/(CO+CO{sub 2}) ratio of 1. At all H{sub 2}/(CO+CO{sub 2}) ratios, the extent …
Date: May 1, 1992
Creator: Al-Adwani, H. A.
System: The UNT Digital Library
Coherent production of pions and rho mesons in neutrino charged current interactions on neon nuclei at the Fermilab Tevatron (open access)

Coherent production of pions and rho mesons in neutrino charged current interactions on neon nuclei at the Fermilab Tevatron

The coherent production of single pions and and {rho} mesons in charged current interactions of neutrinos and antineutrinos on neon nuclei has been studied. The data were obtained using the Fermilab 15-foot Bubble Chamber, filled with a heavy Ne-H{sub 2} mixture and exposed to the Quadrupole Triplet neutrino beam produced by 800 GeV protons from the Tevatron. The average beam energy was 86 GeV. In a sample of 330000 frames, 1032 two-prong {nu}{sub {mu}} + {bar {nu}}{sub {mu}} charged current interactions were selected. The goal of this study was to investigate the low Q{sup 2} high {nu} region where the hadron dominance model can be tested. In this model, the vector and axial-vector parts of the weak hadronic current are dominated by the {rho} and a{sub 1} mesons respectively. Moreover, the Partially Conserved Axial Current (PCAC) hypothesis can be tested by studying the coherent production of single pions.
Date: May 1, 1992
Creator: Willocq, S.
System: The UNT Digital Library
Electrostatic turbulence and transport in the RFP edge (open access)

Electrostatic turbulence and transport in the RFP edge

This thesis details measurements of electrostatic turbulence and transport in the Madison Symmetric Torus reversed field pinch. The electrostatic fluctuation levels are found to be large, with {tilde n}{sub e}/n{sub e} {approximately} 30%--55% and {tilde T}{sub e}/T{sub e} {approximately} 15%--40%. The frequency and wavenumber spectra are broad, with {Delta}n {approximately} 70--150 and {Delta}m {approximately} 3--6, and differ from measured magnetic fluctuation spectra. The transport inferred from coherence measurements indicates that electrostatic fluctuations can account for most of the observed particle losses, but contribute only {approximately}20% to the observed electron energy loss.
Date: May 1, 1992
Creator: Spragins, C. W.
System: The UNT Digital Library
Edge gradient and safety factor effects on electrostatic turbulent transport in tokamaks (open access)

Edge gradient and safety factor effects on electrostatic turbulent transport in tokamaks

Electrostatic turbulence and transport measurements are performed on the Tokapole-II tokamak at the University of Wisconsin-Madison, as the safety-factor and the edge equilibrium gradients and varied substantially. Tokapole-II is a poloidal divertor tokamak capable of operating at a wide range of safety factors due to its unique magnetic limiter configuration. It also has retractable material limiters in a large scrape-off region, which permits the study of edge boundary conditions like density and temperature gradients. The turbulence is independent of safety factor, but strongly sensitive to the local density gradient, which itself depends upon the limiter configuration. When a material limiter is inserted in a high <qa> discharge, the density gradient is increased locally together with a local increase of the turbulence. On the other hand, limiter insertion in low <qa> discharges did not increase the density gradient as much and the turbulence properties are unchanged with respect to the magnetic limiter case. It is conducted then, that electrostatic turbulence is caused by the density gradient. Although the electrostatic fluctuation driven transport is enhanced in the large density gradient case, it is in all cases to small to explain the observed energy confinement times. To explore instabilities with small wavelengths, a …
Date: May 1, 1992
Creator: Tan, Ing Hwie
System: The UNT Digital Library
Implementing Municipal Water Conservation Policy: Goals, Practices and the Case of Texas (open access)

Implementing Municipal Water Conservation Policy: Goals, Practices and the Case of Texas

This study examines whether water conservation is actually being incorporated into municipal water management practices. The development of a conservation policy from a general goal declaration to specific programmatic practices is reviewed for a Texas state water agency, the Texas Water Development Board. From January 1986 through September 1989, 102 political units in Texas applied to the Board for water-related loan funds and thus were required to implement municipal water conservation plans. Two aspects of this conversation policy are assessed: one, the Board's procedural arrangements for the development and review of water conservation plans, and two, the conservation plans of each political unit. It is concluded that Texas state water managers, and local manager also, have yet to incorporate conservation as a significant planning tool for the achievement of water management goals.
Date: May 1992
Creator: Sokulsky, Kariann Elizabeth
System: The UNT Digital Library
Effect of pH on the Persistence and Toxicity of Cyfluthrin to Chironomus Tentans (open access)

Effect of pH on the Persistence and Toxicity of Cyfluthrin to Chironomus Tentans

The effect of pH upon the aquatic toxicity of cyfluthrin was determined in 48 h static acute toxicity tests using 2nd instar Chironomus tentans larvae. Tests were conducted in both dechlorinated tap water and lake water of pH 8.0, 7.2, and 6.6. After 48 h, immobilized and dead larvae were removed and replaced with 2nd instar larvae to assess the persistence of toxicity. Midges were cultured in water adjusted to the pH values used in testing. Toxicity if cyfluthrin varied inversely with pH. An increase in the pH of tap water by 2 units resulted in a 2-decrease in toxicity. Toxicity of cyfluthrin also varied between tap and lake water of the same pH. EC50 values in lake water were approximately 2-3 times lower than those in tap water. Toxicity in the lake water and tap water at every pH tested was also significantly different when regression line elevations were compared. Natural waters amended with cyfluthrin were consistently more toxi to the chironomids than tap water of the same pH. Persistence of cyfluthrin at low pH also influenced chironomid behavior. Recovery of normal behavior generally began within 24 h at pH 8.0 At pH 6.0, recovery did not begin until …
Date: May 1992
Creator: Hambleton, Faith Ann (Faith Ann Elizabeth)
System: The UNT Digital Library
Ode to the Ninth: the Poetic and Musical Tradition Behind the Finale of Beethoven's Choral Symphony (open access)

Ode to the Ninth: the Poetic and Musical Tradition Behind the Finale of Beethoven's Choral Symphony

This study examines the finale of Beethoven's choral symphony and focuses on its inspirations and aims to invoke critical theories involving genre, namely genre's "horizon of expectation", and lead to an enriched perspective that points toward a number of compelling aspects of the Choral Finale overlooked by previous commentators.
Date: May 1992
Creator: Parsons, James, 1956-
System: The UNT Digital Library
Life Histories of Stoneflies (Plecoptera) and Other Aquatic Insects in the Rio Conejos Drainage, Colorado (open access)

Life Histories of Stoneflies (Plecoptera) and Other Aquatic Insects in the Rio Conejos Drainage, Colorado

Stonefly life histories were studied March, 1987 through May, 1990 in the Rio Conejos, Colorado. Adult presence phenology and intensity were monitored daily in the summers of 1988 and 1989 and were coupled with monthly benthic samples to assess nymphal growth. Eggs of several species were reared. Thirty-one species were collected, with several multi-species assemblages occurring in Capnia, Utacapnia, Taenionema, Suwallia, Triznaka, Isogenoides and Isoperla. Sufficient data were obtained to reveal partial or complete life histories of 13 species, five of which have not been previously reported. New information included the 9- to 10-mo egg diapause and semivoltine life histories of Isogenoides zionensis Hanson, Pteronarcella badia (Hagen) and Pteronarcys californica Newport. Additionally, Isoperla phalerata (Smith) had univoltine-slow growth, and L quinquepunctata (Banks) was univoltine-fast. Previously unstudied emergence periods are presented for Triznaka signata (Banks), Suwallia wardi Kondratieff and Kirchner and S. pallidula (Banks). The later two species temporally segregated emergence in both years. Isoperla fulva Claassen emerged in June, and was temporally segregated from its congeners. Regression analysis of cumulative percentage catch revealed two adult presence patterns. Eight species had slopes <7%/d (extended pattern), and only two, I. zionensis and P. cal'fornica, had slopes >7 %/d (synchronous pattern). Several stoneflies …
Date: May 1992
Creator: DeWalt, Ralph Edward
System: The UNT Digital Library
Molecular Mechanism of Action of Steroid Hormone Receptors (open access)

Molecular Mechanism of Action of Steroid Hormone Receptors

A novel bacterial expression system that is capable of producing high levels of soluble, stable, biologically active human vitamin D3 and estrogen receptors has been developed. The method utilizes ubiquitin fusion technology and a low temperature nalidixic acid induction of the lambda PL promoter. This system can produce large quantities of receptor antigen, but only a small fraction displays wild-type DNA and hormone binding properties. Therefore, the use of this system to overproduce receptors for crystallization studies is not practical. To overcome these problems, a 2 um based ubiquitin fusion system which allows regulated expression of the estrogen receptor in yeast (Saccharomyces cerevisiae) was developed. This system produces the estrogen receptor to a level of 0.2% of the total soluble protein. Moreover, this protein is undegradable, soluble, and biologically active. To test the transcriptional activity of the estrogen receptor produced in yeast, a cis-trans transcription assay was developed. This assay revealed that the transcriptional activity of the human estrogen receptor expressed in yeast was similar to that observed in transfected mammalian cells. This reconstituted estrogen transcription unit in Saccharomyces cerevisiae was utilized to examine the regulation of estrogen receptor functions by antiestrogens, to develop a random and rapid approach for …
Date: May 1992
Creator: Nawaz, Zafar
System: The UNT Digital Library
Isolation and Characterization of the Intracellular Granules from the Dental Follicle and Stellate Reticulum of Rat Molars (open access)

Isolation and Characterization of the Intracellular Granules from the Dental Follicle and Stellate Reticulum of Rat Molars

The purpose of this study was to isolate a relatively pure population of granules from the DF and SR of 7 day old rats and characterize them biochemically. If this could be accomplished, the next step was to determine if the granule proteins may play a role in tooth eruption.
Date: May 1992
Creator: Lin, Fan
System: The UNT Digital Library