Language

Molecular biological enhancement of coal biodesulfurization. [Rhodococcus, thiobacillus] (open access)

Molecular biological enhancement of coal biodesulfurization. [Rhodococcus, thiobacillus]

The objective of this project is to produce one or more microorganisms capable of removing the organic and inorganic sulfur in coal. The original specific technical objectives of the project were to: clone and characterize the genes encoding the enzymes of the 4S'' pathway (sulfoxide/sulfone/sulfonate/sulfate) for release of organic sulfur from coal; return multiple copies of genes to the original host to enhance the biodesulfurization activity of that organism; transfer this pathway into a fast-growing chemolithotropic bacterium; conduct a batch-mode optimization/analysis of scale-up variables.
Date: June 14, 1990
Creator: Litchfield, J. H.; Fry, I.; Wyza, R. E.; Palmer, D. T.; Zupancic, T. J. & Conkle, H. N.
Object Type: Report
System: The UNT Digital Library
Inherently safe nuclear-driven internal combustion engines (open access)

Inherently safe nuclear-driven internal combustion engines

A family of nuclear driven engines is described in which nuclear energy released by fissioning of uranium or plutonium in a prompt critical assembly is used to heat a working gas. Engine performance is modeled using a code that calculates hydrodynamics, fission energy production, and neutron transport self-consistently. Results are given demonstrating a large negative temperature coefficient that produces self-shutoff of energy production. Reduced fission product inventory and the self-shutoff provide inherent nuclear safety. It is expected that nuclear engine reactor units could be scaled from 100 MW on up. 7 refs., 3 figs.
Date: June 14, 1991
Creator: Alesso, P.; Chow, Tze-Show; Condit, R.; Heidrich, J.; Pettibone, J. & Streit, R.
Object Type: Article
System: The UNT Digital Library
Ex-vessel core catcher design requirements and preliminary concepts evaluation. [LMFBR] (open access)

Ex-vessel core catcher design requirements and preliminary concepts evaluation. [LMFBR]

As part of the overall study of the consequences of a hypothetical failure to scram following loss of pumping power, design requirements and preliminary concepts evaluation of an ex-vessel core catcher (EVCC) were performed. EVCC is the term applied to a class of devices whose primary objective is to provide a stable subcritical and coolable configuration within containment following a postulated accident in which it is assumed that core debris has penetrated the Reactor Vessel and Guard Vessel. Under these assumed conditions a set of functional requirements were developed for an EVCC and several concepts were evaluated. The studies were specifically directed toward the FFTF design considering the restraints imposed by the physical design and construction of the FFTF plant.
Date: June 14, 1974
Creator: Friedland, A.J. & Tilbrook, R.W.
Object Type: Report
System: The UNT Digital Library
Linear and non-linear calculations of the hose instability in the ion-focused regime (open access)

Linear and non-linear calculations of the hose instability in the ion-focused regime

A simple model is adopted to study the hose instability of an intense relativistic electron beam in a partially neutralized, low density ion channel (ion focused regime). Equations of motion for the beam and the channel are derived and linearized to obtain an approximate dispersion relation. The non-linear equations of motion are then solved numerically and the results compared to linearized data.
Date: June 14, 1982
Creator: Buchanan, H.L.
Object Type: Report
System: The UNT Digital Library
Energy and protein production from pulp mill wastes. Final report, 15 Jun 1976-14 Jun 1979 (open access)

Energy and protein production from pulp mill wastes. Final report, 15 Jun 1976-14 Jun 1979

The goal of this research was to convert the organics and sulfur in sulfite spent liquor (SSL) now classified as pollutants from sulfite pulp mills, into synthetic methane and protein by means of a combination chemical-biological process. Ozonization was used to break the high molecular weight lignosulfonate molecules present in SSL into lower weight fractions which could be metabolized by methane-producing bacteria and protein-producing yeast. Ozonization experiments showed that this treatment is effective in partially oxidizing and fragmenting lignosulfonates into fermentable substrates. This process is initiated at low ozone concentrations and proceeds rapidly until nearly 30% of the Chemical Oxygen Demand (COD) has been consumed. The conditions under which ozonization is conducted greatly affect the degree of oxidation and the molecular weight of the cleaved fragments. In spite of the appreciable oxidative cleavage of the lignosulfonate molecules, continuous-flow fermentation studies showed rather low yields of methane and yeast from ozonated SSL. Under optimum conditions, methane production averaged only 1.7 1/1 of SSL or approximately 3% of the total organics present. Protein production was somewhat more favorable with 6% of the organics being converted to yeast biomass. (6g/1). Neither fermentation fully used all of the oxygenated fragments produced by ozonization, and …
Date: June 14, 1979
Creator: Jurgensen, M. F. & Patton, J. T.
Object Type: Report
System: The UNT Digital Library
Prospects for DNA methods to measure human heritable mutation rates (open access)

Prospects for DNA methods to measure human heritable mutation rates

A workshop cosponsored by ICPEMC and the US Department of Energy was held in Alta, Utah, December 9-13, 1984 to examine the extent to which DNA-oriented methods might provide new approaches to the important but intractable problem of measuring mutation rates in control and exposed human populations. The workshop identified and analyzed six DNA methods for detection of human heritable mutation, including several created at the meeting, and concluded that none of the methods combine sufficient feasibility and efficiency to be recommended for general application. 8 refs.
Date: June 14, 1985
Creator: Mendelsohn, M.L.
Object Type: Article
System: The UNT Digital Library
Production of Gratings for High-Energy Petawatt-Class Lasers (open access)

Production of Gratings for High-Energy Petawatt-Class Lasers

At the time of this writing, we have manufactured and delivered more than 25 multilayer dielectric diffraction gratings from 470-800 mm in long aperture for pulse compression on Petawatt-class,1-micron laser systems being built at government and university facilities in the U.S and elsewhere. We present statistics of diffraction efficiency and its spatial uniformity, diffracted wavefront, and laser damage results on witness gratings. We also discuss yield, failure modes, and manufacturing improvements necessary to improve upon the current state of the art.
Date: June 14, 2006
Creator: Nguyen, H. T.; Carlson, T. C.; Hoaglan, C. R.; Nissen, J. D.; Aasen, M. D.; Peterson, J. E. et al.
Object Type: Article
System: The UNT Digital Library
Enhanced High Temperature Corrosion Resistance in Advanced Fossil Energy Systems by Nano-Passive Layer Formation (open access)

Enhanced High Temperature Corrosion Resistance in Advanced Fossil Energy Systems by Nano-Passive Layer Formation

Due to their excellent corrosion resistance, iron aluminum alloys are currently being considered for use as weld claddings in fossil fuel fired power plants. The susceptibility to hydrogen cracking of these alloys at higher aluminum concentrations has highlighted the need for research into the effect of chromium additions on the corrosion resistance of lower aluminum alloys. In the present work, three iron aluminum alloys were exposed to simulated coal combustion environments at 500 C and 700 C for both short (100 hours) and long (5,000 hours) isothermal durations. Scanning electron microscopy was used to analyze the corrosion products. All alloys exhibited excellent corrosion resistance in the short term tests. For longer exposures, increasing the aluminum concentration was beneficial to the corrosion resistance. The addition of chromium to the binary iron aluminum alloy prevented the formation iron sulfide and resulted in lower corrosion kinetics. A classification of the corrosion products that developed on these alloys is presented. Scanning transmission electron microscopy (STEM) of the as-corroded coupons revealed that chromium was able to form chromium sulfides only on the higher aluminum alloy, thereby preventing the formation of deleterious iron sulfides. When the aluminum concentration was too low to permit selective oxidation of …
Date: June 14, 2007
Creator: Marder, Arnold R.
Object Type: Report
System: The UNT Digital Library
Analysis of cause and mechanism for injection-induced seismicityat the Geysers Geothermal Field, California (open access)

Analysis of cause and mechanism for injection-induced seismicityat the Geysers Geothermal Field, California

We analyzed relative contributions to the cause andmechanism of injection-induced seismicity at The Geysers geothermalfield, California, using coupled thermal-hydrological-mechanicalmodeling. Our analysis shows that the most important cause forinjection-induced seismicity is injection-induced cooling and associatedthermal-elastic shrinkage that changes the stress state in such a waythat mechanical failure and seismicity can be induced. Specifically, thecooling shrinkage results in unloading and associated loss of shearstrength in critically shear-stressed fractures, which are thenreactivated. Thus, our analysis shows that cooling-induced shear slipalong fractures is the dominant mechanism of injection-induced seismicityat The Geysers.
Date: June 14, 2007
Creator: Rutqvist, Jonny & Oldenburg, Curtis
Object Type: Article
System: The UNT Digital Library
Germanium: From Its Discovery to SiGe Devices (open access)

Germanium: From Its Discovery to SiGe Devices

Germanium, element No.32, was discovered in 1886 by Clemens Winkler. Its first broad application was in the form of point contact Schottky diodes for radar reception during WWII. The addition of a closely spaced second contact led to the first all-solid-state electronic amplifier device, the transistor. The relatively low bandgap, the lack of a stable oxide and large surface state densities relegated germanium to the number 2 position behind silicon. The discovery of the lithium drift process, which made possible the formation of p-i-n diodes with fully depletable i-regions several centimeters thick, led germanium to new prominence as the premier gamma-ray detector. The development of ultra-pure germanium yielded highly stable detectors which have remained unsurpassed in their performance. New acceptors and donors were discovered and the electrically active role of hydrogen was clearly established several years before similar findings in silicon. Lightly doped germanium has found applications as far infrared detectors and heavily Neutron Transmutation Doped (NTD) germanium is used in thermistor devices operating at a few milliKelvin. Recently germanium has been rediscovered by the silicon device community because of its superior electron and hole mobility and its ability to induce strains when alloyed with silicon. Germanium is again a …
Date: June 14, 2006
Creator: Haller, E.E.
Object Type: Article
System: The UNT Digital Library
Investigating the Stability and Accuracy of the Phase Response for NOx Sensing 5% Mg-modified LaCrO3 Electrodes (open access)

Investigating the Stability and Accuracy of the Phase Response for NOx Sensing 5% Mg-modified LaCrO3 Electrodes

Impedance spectroscopy measurements were carried out on LaCr{sub 0.95}Mg{sub 0.05}O{sub 3} (LCM) asymmetric interdigitated electrodes supported on fully stabilized 8-mol% Y{sub 2}O{sub 3}-stabilized ZrO{sub 2} (YSZ) electrolytes. Experiments were carried out using 0-50 ppm NO{sub x}, 5-15% O{sub 2} with N{sub 2} as the balance, over temperatures ranging from 600-700 C. AC measurements taken at a constant frequency between 1-100 Hz indicated the phase response of the sensor was less sensitive to fluctuations in the O{sub 2} concentration and the baseline drift was limited. Specific frequencies were observed where the sensor response was essentially temperature independent.
Date: June 14, 2007
Creator: Murray, E. P.; Novak, R. F.; Kubinski, D. J.; Soltis, R. E.; Visser, J. H.; Woo, L. Y. et al.
Object Type: Article
System: The UNT Digital Library
Facility Safety Plan CMS Complexes CMS410 (open access)

Facility Safety Plan CMS Complexes CMS410

Laboratory management requires that the controls specified in this Facility Safety Plan (FSP) be applied to efficiently and safely perform operations within these facilities. Any operation conducted in these facilities that involves activities not commonly performed by the public, requires an Integrated Work Sheet to determine the appropriate level of safety documentation.
Date: June 14, 2007
Creator: Cooper, G
Object Type: Report
System: The UNT Digital Library
Imaging of InGaN inhomogeneities using visible aperturelessnear-field scanning optical microscope (open access)

Imaging of InGaN inhomogeneities using visible aperturelessnear-field scanning optical microscope

The optical properties of epitaxially grown islands of InGaN are investigated with nanometer-scale spatial resolution using visible apertureless near-field scanning optical microscopy. Scattered light from the tip-sample system is modulated by cantilever oscillations and detected at the third harmonic of the oscillation frequency to distinguish the near-field signal from unwanted scattered background light. Scattered near-field measurements indicate that the as-grown InGaN islanded film may exhibit both inhomogeneous In composition and strain-induced changes that affect the optical signal at 633 nm and 532 nm. Changes are observed in the optical contrast for large 3D InGaN islands (100's of nm) of the same height. Near-field optical mapping of small grains on a finer scale reveals InGaN composition or strain-induced irregularities in features with heights of only 2 nm, which exhibit different near-field signals at 633 nm and 532 nm incident wavelengths. Optical signal contrast from topographic features as small as 30 nm is detected.
Date: June 14, 2007
Creator: Stebounova, Larissa V.; Romanyuk, Yaroslav E.; Chen, Dongxue & Leone, Stephen R.
Object Type: Article
System: The UNT Digital Library
Synthetic Nano-Low Density Lipoprotein as Targeted Drug DeliveryVehicle for Glioblastoma Multiforme (open access)

Synthetic Nano-Low Density Lipoprotein as Targeted Drug DeliveryVehicle for Glioblastoma Multiforme

This paper discribes a synthetic low density lipoprotein(LDL) made by complexing a 29 amino acid that consists of a lipid bindingdomain and the LDL receptor binding domain with a lipid microemulsion.The nano-LDL particles were intermdiate in size between LDL and HDL andbound to LDL receptors on GBM brain tumor cells. Synthetic nano-LDLuptake by GBM cells was LDL receptor specific and dependent on cellreceptor number. It is suggested that these synthetic particles can serveas a delivery vehicle for hydophobic anti-tumor drugs by targeting theLDL receptor.
Date: June 14, 2006
Creator: Nikanjam, Mina; Blakely, Eleanor A.; Bjornstad, Kathleen A.; Shu,Xiao; Budinger, Thomas F. & Forte, Trudy M.
Object Type: Article
System: The UNT Digital Library
Identification of Severe Multiple Contingencies in Electric PowerSystems (open access)

Identification of Severe Multiple Contingencies in Electric PowerSystems

In this work, we propose a computationally feasible approachtodetect severe multiple contingencies. We pose a contingency analysisproblem using a nonlinear optimization framework, which enables ustodetect the fewest possible transmission line outages resulting ina systemfailure of specified severity, and the most severe system failure causedby removing a specified number of transmission lines from service.Illustrations using a three bus system and the IEEE ~;30 bus system aimto exhibit the effectiveness of the proposed approach.
Date: June 14, 2006
Creator: Donde, Vaibhav; Lopez, Vanessa; Lesieutre, Bernard; Pinar, Ali; Yang, Chao & Meza, Juan
Object Type: Article
System: The UNT Digital Library
Urban Surfaces and Heat Island Mitigation Potentials (open access)

Urban Surfaces and Heat Island Mitigation Potentials

Data on materials and surface types that comprise a city, i.e. urban fabric, are needed in order to estimate the effects of light-colored surfaces (roofs and pavements) and urban vegetation (trees, grass, shrubs) on the meteorology and air quality of a city. We discuss the results of a semi-automatic statistical approach used to develop data on surface-type distribution and urban-fabric makeup using aerial color orthophotography, for four metropolitan areas of Chicago, IL, Houston, TX, Sacramento, CA, and Salt Lake City, UT. The digital high resolution (0.3 to 0.5-m) aerial photographs for each of these metropolitan areas covers representative urban areas ranging from 30 km{sup 2} to 52 km{sup 2}. Major land-use types examined included: commercial, residential, industrial, educational, and transportation. On average, for the metropolitan areas studied, vegetation covers about 29-41% of the area, roofs 19-25%, and paved surfaces 29-39%. For the most part, trees shade streets, parking lots, grass, and sidewalks. At ground level, i.e., view from below the tree canopies, vegetation covers about 20-37% of the area, roofs 20-25%, and paved surfaces 29-36%.
Date: June 14, 2007
Creator: Akbari, Hashem; Akbari, Hashem & Shea Rose, Leanna
Object Type: Article
System: The UNT Digital Library
Gordon Conference - Cluster, Nanocrystals and Nanostructures - July 29th - August 3rd, 2007 (open access)

Gordon Conference - Cluster, Nanocrystals and Nanostructures - July 29th - August 3rd, 2007

None
Date: June 14, 2007
Creator: A. Welford Castleman, Jr.
Object Type: Report
System: The UNT Digital Library
Growth and structure of water on SiO2 films on Si investigated byKelvin probe microscopy and in situ X-ray Spectroscopies (open access)

Growth and structure of water on SiO2 films on Si investigated byKelvin probe microscopy and in situ X-ray Spectroscopies

The growth of water on thin SiO{sub 2} films on Si wafers at vapor pressures between 1.5 and 4 torr and temperatures between -10 and 21 C has been studied in situ using Kelvin Probe Microscopy and X-ray photoemission and absorption spectroscopies. From 0 to 75% relative humidity (RH) water adsorbs forming a uniform film 4-5 layers thick. The surface potential increases in that RH range by about 400 mV and remains constant upon further increase of the RH. Above 75% RH the water film grows rapidly, reaching 6-7 monolayers at around 90% RH and forming a macroscopic drop near 100%. The O K-edge near-edge X-ray absorption spectrum around 75% RH is similar to that of liquid water (imperfect H-bonding coordination) at temperatures above 0 C and ice-like below 0 C.
Date: June 14, 2007
Creator: Verdaguer, A.; Weis, C.; Oncins, G.; Ketteler, G.; Bluhm, H. & Salmeron, M.
Object Type: Article
System: The UNT Digital Library
Unconventional Magnetism in Low Carrier Density Systems and Nanoparticle Composites (open access)

Unconventional Magnetism in Low Carrier Density Systems and Nanoparticle Composites

Under the auspices of this funding, we have developed a program to synthesize and characterize highly monodispersed magnetic nanoparticles. We have been particularly interested in the origin of the exchange bias effect, which occurs in compound nanoparticles with a ferromagnetic core and an antiferromagnetic shell, and have mostly focused on Co/CoO core-shell nanoparticles. The exchange bias effect involves exchange coupling between the core moment and the antiferromagnetic shell which stabilizes the core moment, which would otherwise be quickly reorienting in ferromagnetic particles of this size.
Date: June 14, 2008
Creator: Aronson, Meigan C
Object Type: Report
System: The UNT Digital Library
A novel method to develop an otolith microchemistry model to determine striped bass habitat use in the San Francisco Estuary (open access)

A novel method to develop an otolith microchemistry model to determine striped bass habitat use in the San Francisco Estuary

Otolith Sr/Ca has become a popular tool for hind casting habitat utilization and migration histories of euryhaline fish. It can readily identify habitat shifts of diadromous fish in most systems. Inferring movements of fish within estuarine habitat, however, requires a model of that accounts of the local water chemistry and the response of individual species to that water chemistry, which is poorly understood. Modeling is further complicated by the fact that high marine Sr and Ca concentrations results in a rapid, nonlinear increase in water Sr/Ca and {sup 87}Sr/{sup 86}Sr between fresh and marine waters. Here we demonstrate a novel method for developing a salinity-otolith Sr/Ca model for the purpose of reconstructing striped bass (Morone saxatilis) habitat use in the San Francisco Bay estuary. We used correlated Sr/Ca and {sup 87}Sr/{sup 86}Sr ratios measurements from adult otoliths from striped bass that experienced a range of salinities to infer striped bass otolith Sr/Ca response to changes in salinity and water Sr/Ca ratio. Otolith {sup 87}Sr/{sup 86}Sr can be assumed to accurately record water {sup 87}Sr/{sup 86}Sr because there is no biological fractionation of Sr isotopes. Water {sup 87}Sr/{sup 86}Sr can in turn be used to estimate water salinity based on the …
Date: June 14, 2006
Creator: Phillis, C C; Ostrach, D J; Gras, M; Yin, Q; Ingram, B L; Zinkl, J G et al.
Object Type: Article
System: The UNT Digital Library
Gamma-ray Mirrors for Direct Measurement of Spent Nuclear Fuel (open access)

Gamma-ray Mirrors for Direct Measurement of Spent Nuclear Fuel

None
Date: June 14, 2013
Creator: Pivovaroff, M. J.; Ziock, K. P.; Fernandez-Perea, M.; Harrison, M. J. & Soufli, R.
Object Type: Article
System: The UNT Digital Library
Raster data transfer test using optigraphics produced data: MIL-R- 28002 Type 1 (Raster) (open access)

Raster data transfer test using optigraphics produced data: MIL-R- 28002 Type 1 (Raster)

The DoD Computer-aided Acquisition and Logistics Support (CALS) Test Network (CTN) is conducting tests of the military standard for the Automated interchange of Technical Information, MIL-STD-1840A, and its companion suite of specifications. The primary purpose of the CTN is to evaluate the effectiveness of the CALS standards for technical data interchange and to demonstrate the capability and operational suitability of these standards. This test was conducted to allow Optigraphics to demonstrate their ability to generated a MIL-R-28002 file. The objective was to evaluate their interpretation of the MIL-R-28002 standard thereby assist the CTN in substantiating the validity of the standards or recommending changes to these standards and the references to national or international standards.
Date: June 14, 1990
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Technology transfer from the space exploration initiative (open access)

Technology transfer from the space exploration initiative

Space exploration has demonstrated that it stimulates the national economy by creating new and improved products, increased employment, and provides a stimulus to education. The exploration of the Moon and Mars under the Space Exploration Initiative has the potential of accelerating this stimulates to the economy. It is difficult to identify all of the concrete ways this will be accomplished. However, many areas can be identified. The space exploration building blocks of power, propulsion, spacecraft, robotics, rovers, mining and manufacturing, communications, navigation, habitats, life support and infrastructures are reviewed to identify possible technology areas. For example, better means for working in hazardous areas and handling hazardous waste are potential outcomes of this initiative. Methods to produce higher quality goods and improve America's competitiveness in manufacturing will undoubtedly evolve from the need to produce products that must last many years in the harsh environments of space and planetary surfaces. Some ideas for technology transfer are covered in this paper.
Date: June 14, 1991
Creator: Buden, D.
Object Type: Article
System: The UNT Digital Library
Acceptable Knowledge Summary Report for Waste Stream: SR-T001-221F-HET/Drums (open access)

Acceptable Knowledge Summary Report for Waste Stream: SR-T001-221F-HET/Drums

This report is fully responsive to the requirements of Section 4.0 Acceptable Knowledge from the WIPP Transuranic Waste Characterization Quality Assurance Plan, CAO-94-1010, and provides a sound, (and auditable) characterization that satisfies the WIPP criteria for Acceptable Knowledge.
Date: June 14, 1999
Creator: Lunsford, G. F.
Object Type: Report
System: The UNT Digital Library