Partner
UNT Libraries Government Documents Department
15,492
Oklahoma Historical Society
8,350
UNT Libraries Special Collections
5,600
Texas Historical Commission
2,549
UNT Libraries
651
UT San Antonio Libraries Special Collections
425
Dr. Pepper Museum
395
Sterling Municipal Library
320
Abilene Christian University Library
307
National WASP WWII Museum
282
177 More
Collection
United States Census Map Collection
7,254
Office of Scientific & Technical Information Technical Reports
7,237
Oklahoma Publishing Company Photography Collection
5,226
Texas Digital Newspaper Program
4,543
KXAS-NBC 5 News Collection
3,457
THC National Register Collection
2,498
Tocker Foundation Grant
2,282
Oklahoma Digital Newspaper Program
1,943
Jim Argo Collection
1,371
Abilene Library Consortium
812
328 More
Serial/Series Title
Degree Department
Degree Discipline
Degree Level
Country
States
Year
Month
The effect of hydrogen isotopes and helium on the tensile properties of 21-6-9 stainless steel
High-energy-rate-forged (HERF) stainless steels are used as the materials of construction for pressure vessels designed for the containment of hydrogen and its isotopes. Hydrogen and helium, the decay product of tritium, are known to embrittle these materials. HERF stainless steels have a relatively good resistance to hydrogen-and-helium-induced embrittlement when compared to annealed stainless steels due to their high number density of dislocations, which act as traps for hydrogen and helium. However, the degree of embrittlement in these materials can vary considerably because of microstructure and yield strength variations introduced during the forging process. In this study the effect of hydrogen and tritium on the tensile properties of 21-6-9 stainless steel was measured as a function of HERF yield strength in the range of 660 to 930 MPa. The effect of microstructure was studied also be conducting tensile tests with HERF and annealed samples.
Date:
December 31, 1990
Creator:
Morgan, M. J. & Lohmeier, D.
Object Type:
Article
System:
The UNT Digital Library
Effect of oxide particle distribution on the helium-induced fracture of copper
Long-term exposure to tritium (H{sup 3}) gas can degrade the mechanical properties of copper alloys while similar exposure to protium (H{sup 1}) gas does not cause such degradation. This difference in behavior is attributed to the presence of helium which is generated by the radioactive decay of tritium. The accumulation of helium, which is virtually insoluble in the copper lattice, can cause the nucleation of cavities along grain boundaries and promote intergranular fracture. Permeation studies have shown that oxide particles act as trap sites for diffusing hydrogen isotopes, and thus may affect the susceptibility of copper to helium-induced degradation by altering the initial tritium distribution in the metal lattice. Tensile and metallographic data demonstrate that oxide particles trap both tritium and helium and decrease the susceptibility of copper to helium-induced intergranular fracture. 25 refs, 3 tabs, 12 figs.
Date:
December 31, 1990
Creator:
Wheeler, D. A.
Object Type:
Article
System:
The UNT Digital Library
The effect of temperature upon the fatigue crack propagation behavior of Alloy 625
Fatigue crack propagation of annealed Alloy 625 was studied in air at 24--649 C. Crack growth rates tend to increase with temperature. Two heats were studied; differences in behavior between them suggest a heat-to-heat variability. Characterization of stress ratio (R=K{sub min}/K{sub max}) effects was also done at 538 C.
Date:
December 31, 1990
Creator:
James, L. A.
Object Type:
Article
System:
The UNT Digital Library
Effect of the slit widths. Appendix A
The aim of this mathematical treatment is to prove that any distortion of the gaussian intensity distribution of the beam, which may be caused by the finite width of the slits, is small, provided that the slit widths are not large with respect to the source size and divergence. The widths of the slit A and of the slit B were the same, equal to 0.1 mm for the measurement of the horizontal source size and divergence, and equal to 0.025 mm in the vertical case. It turns out, as shown below, that the distortion of the phase space gaussian beam distribution is estimated to be not greater than 6% in the vertical case and is considerably smaller in the horizontal case. The procedure followed in the analysis of the experimental data is then justified and is a good approximation.
Date:
December 31, 1990
Creator:
unknown
Object Type:
Report
System:
The UNT Digital Library
Effect of thiamine hydrochloride on the redox reactions of iron at pyrite surface. [Fourth quarterly techical progress report, September 1990--November 1990]
The present investigation is a part of our studies on the electro chemical aspects of pyrite bioleaching involving Thiobacillus ferrooxidans. Previously (1,2) we have examined the effect of T. ferrooxidans and their metabolic products on the redox reactions of Fe{sup 2+}/Fe{sup 3+} couple at the pyrite surface. Results obtained suggest that beyond 1. 5 days during their growth in a batch fermenter, the bacteria and their metabolic products completely cover the pyrite surface and shut down all electron transfer across the electrode-solution interface. In addition, it has been observed that the bacteria serve as the nucleation site for jarosite formation, which is found detrimental to bioleaching. In the present work we have focussed on the effect of the presence of vitamins on the redox chemistry of iron. Our examination of the effect of the presence of thiamine hydrochloride in the redox behavior of Fe{sup 2+}/Fe{sup 3+} at the pyrite surface has revealed that thiamine hydrochloride does not undergo chemical interaction with ferrous or ferric iron. However, it may adsorb onto the pyrite surface causing polarization of the pyrite electrode.
Date:
December 31, 1990
Creator:
Pesic, B. & Oliver, D. J.
Object Type:
Report
System:
The UNT Digital Library
Effects of alpha and gamma radiation on glass reaction in an unsaturated environment
Radiation may effect the long-term performance of glass in an unsaturated repository site by interacting with air, water vapor, or liquid water. The present study examines (1) the effects of alpha or gamma irradiation in a water vapor environment, and (2) the influence of radiolytic products on glass reaction. Results indicate that nitric and organic acids form in an irradiated water vapor environment and are dissolved in thin films of condensed water. Glass samples exposed to these conditions react faster and have a different assemblage of secondary phases than glasses exposed to nonirradiated water vapor environments. 23 refs., 4 figs., 2 tabs.
Date:
December 31, 1990
Creator:
Wronkiewicz, D.J.; Young, J.E. & Bates, J.K.
Object Type:
Article
System:
The UNT Digital Library
Effects of calcium magnesium acetate on the combustion of Coal-Water Slurries. Second quarterly project status report, 1 December 1989--28 February 1990
The general objective of the project is to investigate the combustion behavior of single Coal-Water Slurry particles burning at high temperature environments. Both uncatalyzed as well catalyzed CWS drops with Calcium Magnesium Acetate (CMA) catalyst will be investigated. Emphasis will also be given in the effects of CMA on the sulfur capture during combustion.
Date:
December 31, 1990
Creator:
unknown
Object Type:
Report
System:
The UNT Digital Library
Effects of calcium magnesium acetate on the combustion of Coal-Water Slurry. Third quarterly project status report, 1 March 1990--31 May 1990
The general objective of the project is to investigate the combustion behavior of single and multiple Coal-Water Slurry particles burning at high temperature environments. Both uncatalyzed as well as catalyzed CWS drops with Calcium Magnesium Acetate (CMA) catalyst will be investigated. Emphasis will also be given in the effects of CMA on the sulfur capture during combustion.
Date:
December 31, 1990
Creator:
Levendis, Y. A.
Object Type:
Report
System:
The UNT Digital Library
Effects of catalytic mineral matter on CO/CO{sub 2} ratio, temperature and burning time for char combustion. Quarterly progress report No. 2, January--March 1990
The importance of the CO{sub 2}/CO ratio of carbon oxidation products is illustrated by examination of the heats of reaction for formation of these two products. The heat released by formation of CO{sub 2} is a factor of 3.5 higher than for CO so the temperature of a particle will depend strongly on the CO{sub 2}/CO ratio produced. If gas diffusion through the boundary layer is fast, increased direct production Of CO{sub 2} produces a higher temperature and a higher burning rate. If the supply of oxygen to the surface is limited by diffusion through the boundary layer, production of CO{sub 2} consumes half as much carbon as production of CO so carbon consumption rate is reduced even though temperature may be somewhat higher. Models of these complex interactions have been developed; however the CO{sub 2}/CO ratio produced by the carbon-oxygen reaction must, at present be assumed or inferred from measurement of particle temperature. CO{sub 2}/CO ratios can be strongly influenced by catalytic material in the carbon and by the char temperature. In this program we are measuring the CO{sub 2}/CO ratio for both catalyzed and uncatalyzed chars over a wide range of temperature. These results will then be used …
Date:
December 31, 1990
Creator:
Longwell, J. P.; Sarofim, A. F.; Bar-Ziv, E.; Lee, Chun-Hyuk & Du, Z.
Object Type:
Report
System:
The UNT Digital Library
Effects of catalytic mineral matter on CO/CO{sub 2} ratio, temperature and burning time for char combustion. Quarterly progress report No. 3, April--June 1990
We have extended our recently reported method for determining the surface area of single microporous particles, Dudek et al., 1989 using an electrodynamic chamber (EDC) by increasing the operating pressures from 1 at to 25 at. The value of total surface area is determined from adsorption measurements of CO{sub 2} assuming monolayer adsorption. Measurements of CO{sub 2} desorption were also carried out to yield a point to point difference from the adsorption measurements of about 1%. Adsorption-desorption cycles were carried out for 10 particles to yield a scatter of less than 5% in the measured value for saturation adsorption. The major advantage of using high pressure measurements for evaluating the saturation value for CO{sub 2} adsorption is the improved accuracy of the extrapolation procedure. Previous measurements with the EDC at atmospheric pressure, Dudek, et al., 1989, yielded values for the surface area for similar particles of comparable value with a relative error of about 15%. The results of the high pressure measurements are however bounded with an error of about 3%. Also, the equilibrium adsorption-desorption coefficient was found with a high accuracy, whereas from atmospheric measurements it was not practical to obtain an accurate value.
Date:
December 31, 1990
Creator:
Longwell, J. P.; Sarofim, A. F.; Bar-Ziv, E. & Lee, Chun-Hyuk
Object Type:
Report
System:
The UNT Digital Library
Effects of elevated CO{sub 2} on Chesapeake Bay wetlands. [Progress report, 1988--1989]
Research during 1988--89 focused on several new aspects of the response of the salt marsh ecosystem to elevated CO{sub 2}. In previous years we gave highest priority to studies of the effect of CO{sub 2} on biomass production into above and below-ground tissues, nitrogen content, light response of photosynthesis of single leaves, leaf water potential and carbon dioxide and water vapor exchange between the plant canopy and the ambient air. Result from the work in 87 and 88 had shown that the C3 plant, Scirpus olneyi, responded vigorously to elevated CO{sub 2} but the two C4 species, Spartina patens and Distichlis spicata did not. The responses of photosynthesis were also reflected in the canopy and ecosystem processes. Thus our emphasis shifted from determining the growth responses to exploring photosynthesis in greater detail. The main questions were: does acclimation to high CO{sub 2} involve reduction of some aspect of photosynthesis either at the single leaf level or in canopy structure? How much more carbon will be accumulated in a high CO{sub 2} than under present CO{sub 2} concentration? Our results give us partial answers to these questions but since the long term aspect of CO{sub 2} stimulation remains the most important …
Date:
December 31, 1990
Creator:
Drake, B. G.; Arp, W. J. & Balduman, L.
Object Type:
Report
System:
The UNT Digital Library
The effects of hydrogen isotopes and helium on the tensile properties of 21-6-9 stainless steel
High-energy-rate-forged (HERF) stainless steels are used as the materials of construction for tritium and deuterium reservoirs. Hydrogen and helium, the decay product of tritium, are known to embrittle stainless steels (1--4). The resistance to hydrogen and helium induced embrittlement is relatively good for HERF stainless steels when compared to annealed stainless steels due to their high number density of dislocations, which act as traps for hydrogen and helium. However, the degree of the embrittlement in these materials can vary considerably because of microstructure and yield strength variations introduced during the forging process. In this study the effect of hydrogen and tritium on the room temperature tensile properties of 21-6-9 stainless steel was measured as a function of HERF yield strength in the range of 500 to 918 MPa. The effect of a microstructures was studied also by conducting tensile tests with both HERF samples and annealed samples.
Date:
December 31, 1990
Creator:
Morgan, M. J.
Object Type:
Article
System:
The UNT Digital Library
Effects of sample collection device and filter pore size on concentrations of metals in groundwater samples
The Savannah River Site has conducted a study to statistically quantify differences in metals concentrations as a function of sampling device and filter treatment. Twelve wells screened in unconsolidated coastal plain sediments were sampled for the study. All wells had histories of detectable toxic metals concentrations. Unfiltered and filtered (using 10 and 0.45 micron filters) samples were collected from all wells to evaluate the effects of filtering. To compare the effects of sampling device, the wells were sampled twice, once with a bladder pump and once with a centrifugal pump. An analysis of covariance (ANCOVA) method was used to assess the effects of sampling device and filtration on metals concentrations considering the variation in pH, conductivity, and turbidity among samples. This study demonstrates that when controlled sampling techniques are employed, differences in toxic metals concentrations between filtered and unfiltered samples are not statistically significant. However, variations in sampling devices yield samples with statistically different metals concentrations. The centrifugal pumps, which cause more agitation of the sample and the screened zone than bladder pumps, yield samples with statistically higher metals concentrations.
Date:
December 31, 1990
Creator:
Clark, S. B.; Park, N. M. & Tuckfield, R. C.
Object Type:
Article
System:
The UNT Digital Library
Eighth international congress on nitrogen fixation. Final program
This volume contains the proceedings of the Eighth International Congress on Nitrogen Fixation held May 20--26, 1990 in Knoxville, Tennessee. The volume contains abstracts of individual presentations. Sessions were entitled Recent Advances in the Chemistry of Nitrogen Fixation, Plant-microbe Interactions, Limiting Factors of Nitrogen Fixation, Nitrogen Fixation and the Environment, Bacterial Systems, Nitrogen Fixation in Agriculture and Industry, Plant Function, and Nitrogen Fixation and Evolution.
Date:
December 31, 1990
Creator:
unknown
Object Type:
Article
System:
The UNT Digital Library
Electrochemical oxidation of organic waste
Both silver catalyzed and direct electrochemical oxidation of organic species are examined in analytical detail. This paper describes the mechanisms, reaction rates, products, intermediates, capabilities, limitations, and optimal reaction conditions of the electrochemical destruction of organic waste. A small bench-top electrocell being tested for the treatment of small quantities of laboratory waste is described. The 200-mL electrochemical cell used has a processing capacity of 50 mL per day, and can treat both radioactive and nonradioactive waste. In the silver catalyzed process, Ag(I) is electrochemically oxidized to Ag(II), which attacks organic species such as tributylphosphate (TBP), tetraphenylborate (TPB), and benzene. In direct electrochemical oxidation, the organic species are destroyed at the surface of the working electrode without the use of silver as an electron transfer agent. This paper focuses on the destruction of tributylphosphate (TBP), although several organic species have been destroyed using this process. The organic species are converted to carbon dioxide, water, and inorganic acids.
Date:
December 31, 1990
Creator:
Almon, A. C. & Buchanan, B. R.
Object Type:
Article
System:
The UNT Digital Library
Electron beam optics for the FEL experiment and IFEL experiment
Electron beam transport system parameters for the FEL experiment and for the FEL experiment are given. The perturbation of the ``interaction region`` optics due to wiggler focussing is taken into account and a range of solutions are provided for relevant Twiss parameters in the FEL or IFEL region. Modifications of the transport optics in specific sections of the overall beam transport lines, for reasons of enhanced diagnostic capability or enhanced beam momentum analysis resolution, is also presented.
Date:
December 31, 1990
Creator:
van Steenbergen, A.
Object Type:
Report
System:
The UNT Digital Library
Energy aspects of solid waste management: Proceedings
The Eighteenth Annual Illinois Energy Conference entitled ``Energy Aspects of Solid Waste Management`` was held in Chicago, Illinois on October 29--30, 1990. The conference program was developed by a planning committee that drew upon Illinois energy and environmental specialists from the major sectors including energy industries, environmental organizations, research universities, utility companies, federal, state and local government agencies, and public interest groups. Within this framework, the committee identified a number of key topic areas surrounding solid waste management in Illinois which were the focus of the conference. These issues included: review of the main components of the solid waste cycle in the Midwest and what the relative impact of waste reduction, recycling, incineration and land disposal might be on Illinois` and the Midwest`s solid waste management program. Investigation of special programs in the Midwest dealing with sewage sludge, combustion residuals and medical/infectious wastes. Review of the status of existing landfills in Illinois and the Midwest and an examination of the current plans for siting of new land disposal systems. Review of the status of incinerators and waste-to-energy systems in Illinois and the Midwest, as well as an update on activities to maximize methane production from landfills in the Midwest.
Date:
December 31, 1990
Creator:
unknown
Object Type:
Article
System:
The UNT Digital Library
Energy dependent neutron imaging
A waste package consisting of a container and high-level nuclear waste is being developed for the permanent disposal of radioactive waste. Yucca Mountain, Nevada, is being studied as a potential site for the underground high-level nuclear waste repository. A major consideration for choosing Yucca Mountain is the presence of zeolite in tertiary ash-flow tuffs. The presence of zeolites could provide geological barriers to radionuclide migration. The suitability of the tuffaceous rocks at Yucca Mountain for the repository is being investigated since the properties of the environment around a waste site must be well characterized to reliably predict performance. The results of experiments at Lawrence Livermore National Laboratory (LLNL) to assess the possibility of imaging water in Nevada Test Site welded tuff samples showed that nuclear magnetic resonance imaging is not viable. This leaves neutron tomography and high-frequency electromagnetic geotomography as possibilities for the practical imaging of distribution and flow of fluids in rock, including tuff specimens. Water tracers are needed in electromagnetic tomography techniques since the contrast for detecting water in cracks of tuff is lower than in granite because of the higher porosity in tuff. The results of preliminary testing with geotomography by LLNL indicates relatively low spatial resolution. …
Date:
December 31, 1990
Creator:
Kupperman, D.S.; Hitterman, R.L. & Rhodes, E.
Object Type:
Article
System:
The UNT Digital Library
[Enhancement of photoassimilate utilization by manipulation of the ADPglucose pyrophosphorylase gene]. Progress report, [March 15, 1989--April 14, 1990]
The long term aim of this project is to assess the feasibility of increasing the conversion of photosynthate into starch via manipulation of the gene that encodes for ADPglucose pyrophosphorylase, a key regulatory enzyme of starch biosynthesis. In developing storage tissues such as cereal seeds and tubers, starch biosynthesis is regulated by the gene activation and expression of ADPglucose pyrophosphorylase, starch synthase, branching enzyme and other ancillary starch modifying enzymes, as well as the allosteric-controlled behavior of ADPglucose pyrophosphorylase activity. During the last two years we have obtained information on the structure of this enzyme from both potato tuber and rice endosperm, using a combination of biochemical and molecular biological approaches. Moreover, we present evidence that this enzyme may be localized at discrete regions of the starch grain within the amyloplast, and plays a role in controlling overall starch biosynthesis in potato tubers.
Date:
December 31, 1990
Creator:
Okita, T. W.
Object Type:
Report
System:
The UNT Digital Library
Enhancement of photoassimilate utilization by manipulation of the ADPglucose pyrophosphorylase genes. Progress report, [April 15, 1990--April 14, 1991]
The long term goal of this project is to assess the feasibility of increasing the conversion of photosynthate a key regulatory enzyme in starch biosynthesis. In developing storage tissues such as cereal seeds and tubers, starch biosynthesis is primarily regulated by the gene activation, expression, and allosteric regulation of ADPglucose pyrophosphorylase, as well as starch synthase, and branching enzyme. During the last year we have elucidated the structure of both subunits which compose this tetrameric enzyme and determined the temporal and spatial expression of the genes encoding each subunit as well as their correlation to starch biosynthesis. Genomic clones to both subunits have also been isolated and the gene structure of the small subunit determined. Transgenic potato plants have been produced containing deletions of the small subunit promoter. Currently, cis acting elements and their involvement in spatial and temporal expression are under investigation.
Date:
December 31, 1990
Creator:
Okita, T. W.
Object Type:
Report
System:
The UNT Digital Library
Environmental factors affecting distribution and abundance of bacteria, fungi and protozoa in subsurface sediments of the Upper Atlantic Coastal Plain, USA
Exploratory statistical analyses of microbiological, hydrological and geochemical data for samples from four boreholes drilled into Upper Atlantic Coastal Plain sediments near the Savannah River Site, SC, showed highly significant correlations between bacterial abundance (AODC and CFU) and hydraulic conductivity (K). Sediment texture variables (% sand (S), % silt, % clay (C), and S/C) were strongly interrelated with K and, therefore, also correlated with bacterial abundance. AODC did not correlate with the concentrations of dissolved inorganic nitrogen (DIN) or dissolved organic carbon (DOC) in pore water. CFU also did not correlate with DIN, but a negative relationship was found between the CFU and DOC for sandy sediments, suggesting that microbial activity may control pore water DOC concentration. In some, but not all boreholes, AODC and CFU correlated negatively with pore water concentrations of metals and positively with pH. Protozoan abundance correlated strongly with AODC and CFU in the two boreholes closest to the recharge areas for their major aquifers. It also correlated with sediment texture variables, but not with K. Fungal abundance did not correlate with the abundance of other microbial types when data from individual boreholes were considered; however it did correlate with both bacterial and protozoan abundance when …
Date:
December 31, 1990
Creator:
Levine, S. N. & Ghiorse, W. C.
Object Type:
Article
System:
The UNT Digital Library
Environmental Parameters Controlling Microbial Activities in Terrestrial Subsurface Environments. Technical Completion Report.
This project was begun in July 1988 as part of Phase I of the Deep Microbiology Subprogram. At this time, the Subprogram was preparing for sampling near the Savannah River Site (SRS) from what was being termed the ``Investigator`s Hole.`` This was the fourth hole drilled for sampling in the coastal plain sediments at a site near the SRS. Since there was a possibility of sampling from the saline Triassic basin in the deeper regions in this fourth hole, there was particular interest in quantifying halotolerant microorganisms from these samples and in determining the responses of subsurface microbes to a range of soft concentrations. Further interest in the soft tolerances of microbes from these coastal sediments arose from the fact that all of these sediments were deposited under marine conditions. It was also anticipated that samples would be available from the shallow unsaturated (vadose) zone at this site, so there was interest in quantifying microbial responses to matric water potential as well as solute water potential. The initial objectives of this research project were to: characterize microbial communities in a saline aquifer; determine the potential for microbial metabolism of selected organic compounds in a saline aquifers; characterize microbial communities in …
Date:
December 31, 1990
Creator:
Kieft, Thomas L.
Object Type:
Report
System:
The UNT Digital Library
D-erythroascorbic acid: Its preparations, chemistry, and metabolism (fungi and plants). Second year [annual] report, [May 23, 1988--May 22, 1990]
Sclerotinia sclerotiorum contains D-erythroascorbic acid (EAA) and a closely related reducing acid, possibly the open-chain form of EAA. The organism cleaves one of these products or possibly both to yield OA and D-glyceric acid. The OA is rapidly secreted into the medium. An analogy can be made between AA-linked OA biosynthesis in higher plants and EAA-linked OA biosynthesis in fungi as exemplified by S. sclerotiorum.
Date:
December 31, 1990
Creator:
Loewus, F. A. & Seib, P. A.
Object Type:
Report
System:
The UNT Digital Library
ESPY measurements of submerged composite plate vibrations
An Electronic Speckle pattern interferometer (ESPI) was constructed which performs full-field surface displacement measurements. This measurement technique when combined with a single-point measurement known as laser vibrometry, can completely determine the vibrational characteristics of complex structures. This information can, in turn, be used for nondestructive testing as well as for modal analysis. One NDT&E technique is to vibrationally excite the object and evaluate the time averaged interferograms from the ESPI and the vibration spectra from the vibrometer. Anomalies in the interferograms can be related to subsurface defects such as defective weld joints, internal cracks, voids, etc. All of this can be accomplished in a noncontacting and nonintrusive manor. In many instances, a finite element analysis in concert with this approach can be useful in interpreting the results. Since ESPI is analogous to optical holography, other methods equivalent to real-time and double-pulse holography may also be easily applied. As in holography, EXSPI is sensitive to out-of-plane surface displacements. Other optical arrangements can be implemented with the same equipment to give in-plane displacements which would give results similar to Moire interferometry without the need to apply gratings to the object under test. The advantage of this method over holographic interferometry is that …
Date:
December 31, 1990
Creator:
Pechersky, M. J.
Object Type:
Article
System:
The UNT Digital Library