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LOW TEMPERATURE COOPERATIVE BEHAVIOR OF THE RARE EARTH SALTS GdCl$sub 3$ AND PrCl . (open access)

LOW TEMPERATURE COOPERATIVE BEHAVIOR OF THE RARE EARTH SALTS GdCl$sub 3$ AND PrCl .

None
Date: January 1, 1971
Creator: Hessler, J.P.
System: The UNT Digital Library
Fall and winter movements and activity of muskrats in east-central Minnesota (open access)

Fall and winter movements and activity of muskrats in east-central Minnesota

None
Date: August 1, 1974
Creator: Stolen, Paul Dean
System: The UNT Digital Library
Formal analysis of name accessing in programming languages. [R] (open access)

Formal analysis of name accessing in programming languages. [R]

None
Date: October 1, 1975
Creator: Smith, C. L.
System: The UNT Digital Library
Response of Shortgrass Plains Vegetation to Chronic and Seasonally Administered Gamma Radiation (open access)

Response of Shortgrass Plains Vegetation to Chronic and Seasonally Administered Gamma Radiation

In order to determine the effect of radiation on the structure of native shortgrass plains vegetation, an 8750 Ci 137Cs source was installed on the Central Plains Experimental Range near Nunn, Colorado; The experimental area was divided into 6 treatment sectors, a control, 2 sectors for chronic exposure (irradiation initiated April 1969 and continuing as of August 1971), and one each for spring, summer and late fall seasonal semi-acute (30 day), exposures which were administered during April, July and December, 1969, respectively. Community structure was measured by coefficient of community and diversity index. Yield was determined by clipping plots in September 1970 and visual estimates in September 1969 and 1970 for the grass-sedge component of the vegetation. Individual species sensitivity was determined by density data recorded in April, June and September of 1969 and 1970 and by a phenological index recorded at weekly intervals during the 1969 and 1970 growing seasons. The response of the vegetation was similar whether determined by coefficient of community or diversity with diversity being a more sensitive measure of effects. In the chronically exposed sectors, the exposure rate which resulted in a 50 per cent reduction in these 2 parameters (CC50 or D50) was still …
Date: August 1, 1971
Creator: Fraley, L. Jr.
System: The UNT Digital Library
Low temperature heat capacity of lutetium and lutetium hydrogen alloys (open access)

Low temperature heat capacity of lutetium and lutetium hydrogen alloys

The heat capacity of high purity electrotransport refined lutetium was measured between 1 and 20/sup 0/K. Results for theta/sub D/ were in excellent agreement with theta values determined from elastic constant measurements. The heat capacity of a series of lutetium-hydrogen solid solution alloys was determined and results showed an increase in ..gamma.. from 8.2 to about 11.3 mJ/g-atom-K/sup 2/ for hydrogen content increasing from zero to about one atomic percent. Above one percent hydrogen ..gamma.. decreased with increasing hydrogen contents. The C/T data showed an increase with temperature decreasing below about 2.5/sup 0/K for samples with 0.1 to 1.5 atomic percent hydrogen. This accounts for a large amount of scatter in theta/sub D/ versus hydrogen content in this range. The heat capacity of a bulk sample of lutetium dihydride was measured between 1 and 20/sup 0/K and showed a large increase in theta/sub D/ and a large decrease in ..gamma.. compared to pure lutetium.
Date: October 1, 1977
Creator: Thome, D. K.
System: The UNT Digital Library
Polariton effects in naphthalene crystals (open access)

Polariton effects in naphthalene crystals

The experimental verification of the two-step nature of energy dissipation of photon energy by a crystal is the subject of this dissertation. The ..cap alpha..(O,O) Davydov component of the lowest energy singlet transition in pure strain-free napthalene single crystals is shown to exhibit an increase in absorption with increasing temperature, due to an increase in polariton damping via polariton-phonon scattering processes. (GHT)
Date: October 1, 1977
Creator: Robinette, S. L.
System: The UNT Digital Library
Synthesis and characterization of an N-(2-hydroxyethyl)-ethylenediaminetriacetic acid resin (open access)

Synthesis and characterization of an N-(2-hydroxyethyl)-ethylenediaminetriacetic acid resin

A chelating ion-exchange resin with N-(2-hydroxyethyl)ethylene-diaminetriacetic acid (HEDTA) used as the ligand chemically bonded to XAD-4 by an ester linkage, HEDTA-4, was synthesized. It is stable under normal experimental conditions with the liquid chromatograph. The structure of the resin was confirmed by an infrared spectrum, and by potentiometric titrations. The capacity of the resin was also obtained by potentiometric titration and by a nitrogen analysis. The resin was used to pack a column of 5 mm internal diameter and 5 cm long. The effect of pH on the retention of different metal ions on the resin was studied. It was found that the resin was most selective for chromium(III), copper(II), lead(II), mercury(II), uranium(VI), zirconium(IV) and zinc(II) at a pH of less than 3. Furthermore, the resin proves to be functioning with a chelating mechanism rather than ion-exchange, and it can concentrate trace metal ions in the presence of a large excess of calcium and magnesium. This makes the resin potentially useful for purifying and analyzing drinking water.
Date: October 1, 1977
Creator: Lai, Y. F.
System: The UNT Digital Library
Electron microscopy of hydrocarbon production in parthenium argentatum (guayule) (open access)

Electron microscopy of hydrocarbon production in parthenium argentatum (guayule)

The electron microscope was used to study the biological processes involved in hydrocarbon production. The little desert shrub Guayule (Parthenium argentatum) was selected for study. This shrub can produce hydrocarbons (rubber) in concentrations up to 1/4 of its dry weight. It grows on semi-arid land and has been extensively studied. The potential of Guayule is described in detail. Results of an investigation into the morphology of Guayule at the electron microscope level are given. Experiments, which would allow the biosynthesis of hydrocarbon in Guayule to be followed, were designed. In order to do this, knowledge of the biochemistry of rubber formation was used to select a tracer, mevalonic acid. Mevalonic acid is the precursor of all the terpenoids, a large class of hydrocarbons which includes rubber. It was found that when high enough concentrations of mevalonic acid are administered to seedling Guayule plants, build-ups of metabolized products are found within the chloroplasts of the seedlings. Also, tritium labeled mevalonic acid was used as a precursor, and its metabolic progress was followed by using the technique of electron microscope autoradiography. The results of these experiments also implicated chloroplasts of the Guayule plant in hydrocarbon production. The final task was the development …
Date: November 1, 1977
Creator: Bauer, T.E.
System: The UNT Digital Library
Stress induced reorientation of vanadium hydride (open access)

Stress induced reorientation of vanadium hydride

The critical stress for the reorientation of vanadium hydride was determined for the temperature range 180/sup 0/ to 280/sup 0/K using flat tensile samples containing 50 to 500 ppM hydrogen by weight. The critical stress was observed to vary from a half to a third of the macroscopic yield stress of pure vanadium over the temperature range. The vanadium hydride could not be stress induced to precipitate above its stress-free precipitation temperature by uniaxial tensile stresses or triaxial tensile stresses induced by a notch.
Date: October 1, 1977
Creator: Beardsley, M. B.
System: The UNT Digital Library
Electromigration of hydrogen and deuterium in vanadium, niobium, and tantalum (open access)

Electromigration of hydrogen and deuterium in vanadium, niobium, and tantalum

The electric mobility and effective valence of hydrogen and deuterium in vanadium, niobium, tantalum and three niobium-tantalum alloys were measured. A resistance technique was used to directly determine the electric mobility of hydrogen and deuterium at 30/sup 0/C while a steady-state method was used to measure the effective valence. The use of mass spectrographic techniques on a single specimen which contained both hydrogen and deuterium greatly increased the precision with which the isotope effect in the effective valence could be measured.
Date: October 1, 1977
Creator: Jensen, C. L.
System: The UNT Digital Library
Use of a semiconductor laser in infrared spectroscopy (open access)

Use of a semiconductor laser in infrared spectroscopy

A semiconductor laser has certain properties which makes its use desirable as a continuous monitor of atmospheric pollutants. Its energy output is concentrated in widely separated energy modes of very narrow bandwidths (less than 10/sup -5/ cm/sup -1/) which can be centered on one infrared absorption line of one gas. This makes the laser quite selective. The energy in each mode is typically greater than 200 ..mu.. watts, and, because of the laser's small size, its light energy can be collimated over large distances with minimal optical losses and be easily detected. One can rapidly measure the decrease in transmission of the light due to the absorption of the light by the gas being monitored, and, using certain analytical parameters, which are different for each absorption line, one can determine the concentration of the gas in question immediately. In addition to the line center (nu/sub 0/), these analytical parameters are the intensity (S) and the half width at half maximum (..gamma..). The intensity (S) is dependent only on temperature when expressed in a per concentration basis and ..gamma.. is dependent on pressure. The Lorentzian lineshape equation K(nu) + S/..pi gamma..(((nu - nu/sub 0/)/..gamma..)/sup 2/ + 1)/sup -1/ is the equation …
Date: December 1, 1977
Creator: Morris, R. N.
System: The UNT Digital Library
Temperature dependence of resistivity of thin film samples of chalcogenide glasses (open access)

Temperature dependence of resistivity of thin film samples of chalcogenide glasses

None
Date: October 1, 1975
Creator: Kulkarni, A. K.
System: The UNT Digital Library
Inductively coupled plasma--atomic emission spectrometry: trace elements in oil matrices (open access)

Inductively coupled plasma--atomic emission spectrometry: trace elements in oil matrices

The simultaneous determination of up to 20 trace elements in various oil matrices by inductively coupled plasma-atomic emission spectrometry is reported. The oil matrices investigated were lubricating oils (for wear metals), fuel oil, centrifuged coal liquefaction product, crude soybean oil, and commercial edible oils. The samples were diluted with appropriate organic solvents and injected into the plasma as an aerosol generated by a pneumatic nebulization technique. Detection limits of the 28 elements studied ranged from 0.0006 to 9 ..mu..g/g with the majority falling in the 0.01 to 0.1 ..mu..g/g range. Analytical calibration curves were linear over at least two orders of magnitude and for some elements this linearity extended over 4.5 orders of magnitude. Relevant data on precision and accuracy are included. Because metals often occur as particles in lubricating oil and coal liquefaction products, the effect of particles on the analytical results was examined. Wear metal particles in used oil did not appear to affect the analytical results. However, incomplete recovery relative to organometallic reference solutions was obtained for iron particles with a nominal mean diameter of 3.0 ..mu..m suspended in oil. It was shown that the following factors contributed to incomplete recovery for the particles: settling of the …
Date: December 1, 1977
Creator: Peterson, C. A.
System: The UNT Digital Library
Analytical applications of resins containing amide and polyamine functional groups (open access)

Analytical applications of resins containing amide and polyamine functional groups

A dibutyl amide resin is used for the separation of uranium(VI), thorium(IV), and zirconium(IV) from each other and several other metal ions. Uranium(VI) and thorium(IV) are determined in the presence of large excesses of foreign metal ions and anions. A practical application of the amide resin is studied by determining uranium in low grade uranium ores. The amide resin is also used for the selective concentration of gold(III) from sea water.
Date: December 1, 1977
Creator: Orf, G. M.
System: The UNT Digital Library
Dislocation morphology in deformed and irradiated niobium. [Neutron irradiation] (open access)

Dislocation morphology in deformed and irradiated niobium. [Neutron irradiation]

Niobium foils of moderate purity were examined for the morphology of dislocations or defect clusters in the deformed or neutron-irradiated state by transmission electron microscopy. New evidence has been found for the dissociation of screw dislocations into partials on the (211) slip plane according to the Crussard mechanism: (a/2) (111) ..-->.. (a/3) (111) + (a/6) (111).
Date: June 1, 1977
Creator: Chang, C. P.
System: The UNT Digital Library
Lanthanide extraction with 2,5-dimethyl-2-hydroxyhexanoic acid (open access)

Lanthanide extraction with 2,5-dimethyl-2-hydroxyhexanoic acid

This research is concerned with the solvent extraction into chloroform of the lanthanides, using 2,5-dimethyl-2-hydroxyhexanoic acid (DMHHA). This acid is the first ..cap alpha..-hydroxy aliphatic acid to be studied as an extracting agent for the lanthanides. The chloroform-water DMHHA partition constant was determined to be 1.0 (at 0.1 M ionic strength and 25/sup 0/C). The acid dimerizes in chloroform with a constant of 56. The light lanthanides can be extracted into chloroform by forming complexes with the DMHHA anions. The extracted metal species is highly aggregated. This extraction has a solubility limit which increases with the addition of unionized acid. The resultant extract is also highly aggregated. At unionized acid-to-metal ratios greater than one, extractions first occur followed by the slow precipitation of the lanthanide. At the tracer level, neodymium is extracted primarily as NdA/sub 3/(HA)/sub 5/ and (NdA/sub 3/)/sub 2/(HA)/sub q/. Very small amounts of (NdA/sub 3/)/sub 2/ and other metal aggregates are also present. The heavy lanthanides do not extract from solutions of DMHHA and its potassium salt, but form aqueous emulsions and precipitates. In the presence of the organic soluble tetrabutylammonium ion the heavy lanthanides can be extracted, presumably as ion pairs. The stability constants of the …
Date: December 1, 1977
Creator: Miller, J. H.
System: The UNT Digital Library
Anomalous Radial Plasma Losses in a Q-Machine With Mirror Magnetic Fields. (open access)

Anomalous Radial Plasma Losses in a Q-Machine With Mirror Magnetic Fields.

None
Date: April 1972
Creator: Searing, Richard Manor
System: The UNT Digital Library
Magnetic excitations above the critical temperature (open access)

Magnetic excitations above the critical temperature

None
Date: October 1, 1975
Creator: Swanson, P. A.
System: The UNT Digital Library
Investigation of high energy runaway electron confinement in the Oak Ridge tokamak (open access)

Investigation of high energy runaway electron confinement in the Oak Ridge tokamak

High energy runaway electrons in the Oak Ridge tokamak ORMAK have been investigated through measurement of the bremsstrahlung produced when these electrons leave the discharge and strike the limiting aperture of the torus. The experimental results have been interpreted in terms of a classical single-particle model appropriate for collisionless particles in a tokamak, and it has been found that most of the confinement properties of high energy runaways in ORMAK can be understood on this basis. An experiment designed to directly test this model has disclosed an anomalous transport which has been described by a runaway diffusion coefficient D approximately 10/sup 2/ to 10/sup 4/ cm/sup 2//sec appropriate for runaways near the outside of the plasma. A discussion of the possible mechanisms for this anomalous transport is given.
Date: November 1, 1977
Creator: Zweben, S. J.
System: The UNT Digital Library
ELECTRON TRANSFER REACTIONS OF FERROCENE. (open access)

ELECTRON TRANSFER REACTIONS OF FERROCENE.

None
Date: January 1, 1971
Creator: Pladziewicz, J R
System: The UNT Digital Library
Heated uranium tetrafluoride target system to release non-rare gas fission products for the TRISTAN isotope separator. [As replacement for uranyl stearate] (open access)

Heated uranium tetrafluoride target system to release non-rare gas fission products for the TRISTAN isotope separator. [As replacement for uranyl stearate]

Off-line experiments indicated that fluorides of As, Se, Br, Kr, Zr, Nb, Mo, Tc, Ru, Sb, Te, I and Xe could be volatilized, but except for Br, Kr, I and Xe, none of these elements were observed after mass separation in the on-line experiments. The results of the on-line experiments indicated a very low level of hydride contamination at ambient temperature and consequently, uranium tetrafluoride replaced uranyl stearate as the primary gaseous fission product target. Possible reasons for the failure of the heated target system to yield non-rare gas activities are discussed and suggestions for designing a new heated target system are presented.
Date: October 1, 1977
Creator: Gill, R. L.
System: The UNT Digital Library
Photoexcitation in Superconductors (open access)

Photoexcitation in Superconductors

Dissertation discussing the results of experiments to study the behavior of superconductors under light illumination.
Date: June 1976
Creator: Schuller, Ivan
System: The UNT Digital Library
The Relationship of Fifth-Grade Students' Self-Concepts and Attitudes toward Mathematics to Academic Achievement in Arithmetical Computation, Concepts, and Application (open access)

The Relationship of Fifth-Grade Students' Self-Concepts and Attitudes toward Mathematics to Academic Achievement in Arithmetical Computation, Concepts, and Application

The purpose of this study was to determine the interrelationship of self-concept and attitude toward mathematics to academic achievement in the areas of arithmetical computation, concepts, and application.
Date: August 1971
Creator: Moore, Bobbie Dean
System: The UNT Digital Library