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{sup 17}O NMR investigation of oxidative degradation in polymers under gamma-irradiation

Description: The {gamma}-irradiated-oxidation of pentacontane (C{sub 50}H{sub 102}) and the polymer polyisoprene was investigated as a function of oxidation level using {sup 17}O nuclear magnetic resonance (NMR) spectroscopy. It is demonstrated that by using {sup 17}O labeled O{sub 2} gas during the {gamma}-irradiation process, details about the oxidative degradation mechanisms can be directly obtained from the analysis of the {sup 17}O NMR spectra. Production of carboxylic acids is the primary oxygen-containing functionality during the oxidation of pentacontane, while ethers and alcohols are the dominant oxidation product observed for polyisoprene. The formation of ester species during the oxidation process is very minor for both materials, with water also being produced in significant amounts during the radiolytic oxidation of polyisoprene. The ability to focus on the oxidative component of the degradation process using {sup 17}O NMR spectroscopy demonstrates the selectivity of this technique over more conventional approaches.
Date: March 8, 2000
Creator: ALAM,TODD M.; CELINA,MATHIAS C.; ASSINK,ROGER A.; CLOUGH,ROGER LEE & GILLEN,KENNETH T.
Partner: UNT Libraries Government Documents Department

Reduction of Tropical Cloudiness by Soot

Description: Measurements and models show that enhanced aerosol concentrations can augment cloud albedo not only by increasing total droplet cross-sectional area, but also by reducing precipitation and thereby increasing cloud water content and cloud coverage. Aerosol pollution is expected to exert a net cooling influence on the global climate through these conventional mechanisms. Here we demonstrate an opposite mechanism through which aerosols can reduce cloud cover and thus significantly offset aerosol-induced radiative cooling at the top of the atmosphere on a regional scale. In model simulations the daytime clearing of trade cumulus is hastened and intensified by solar heating in dark haze (as found over much of the northern Indian Ocean during the northeast monsoon).
Date: May 8, 2000
Creator: Ackerman, A. S.; Toon, O. B.; Stevens, D. E.; Heymsfield, A. J. & Ramanathan, V.
Partner: UNT Libraries Government Documents Department

Irradiation of Nd-Fe-B permanent magnets with APS bending magnet x-rays and {sup 60}Co {gamma}-rays

Description: The Advanced Photon Source (APS), as well as other third-generation synchrotron light sources, uses permanent magnets in the insertion devices to produce x-rays for scientific research. When placed in a high-energy storage ring, these permanent magnets are subjected to irradiation from synchrotron radiation, high-energy bremsstrahlung, and bremsstrahlung-produced photoneutrons. Previous investigations have exhibited varying degrees of degradation in the intensity of magnetization of these magnets due to irradiation from electron beams, {sup 60}Co {gamma}rays, and high-energy neutrons. The APS specifically uses Nd-Fe-B permanent magnets in their insertion devices. Although no detectable radiation-induced demagnetization has been observed in the APS insertion devices so far, partial demagnetization has been observed in at least one insertion device at the European Synchrotron Radiation Facility (ESRF), where Nd-Fe-B permanent magnets are also used.
Date: September 8, 2000
Creator: Alderman, J.; Job, P. K. & Puhl, J.
Partner: UNT Libraries Government Documents Department

Stress Corrosion Cracking of Annealed and Cold Worked Titanium Grade 7 and Alloy 22 in 110 C Concentrated Salt Environments

Description: Stress corrosion crack growth studies have been performed on annealed and cold worked Titanium Grade 7 and Alloy 22 in 110 C, aerated, concentrated, high pH salt environments characteristic of concentrated ground water. Following a very careful transition from fatigue precracking conditions to SCC conditions, the long term behavior under very stable conditions was monitored using reversing dc potential drop. Titanium Grade 7 exhibited continuous crack growth under both near-static and complete static loading conditions. Alloy 22 exhibited similar growth rates, but was less prone to maintain stable crack growth as conditions approached fully static loading.
Date: November 8, 2000
Creator: Andresen, P.
Partner: UNT Libraries Government Documents Department

Advanced Industrial Materials (AIM) Program Compilation of Project Summaries and Significant Accomplishments FY 1999

Description: For the past 10 years the Advanced Industrial Materials (AIM) has supported development of new and improved materials to enable U.S. industry to improve energy efficiency, increase productivity, and reduce waste. It has been a National Laboratory based program, with work currently under way at Oak Ridge National Laboratory, Los Alamos National Laboratory, and Sandia National Laboratories, in collaboration with industrial and university partners. With the advent of the Industries of the Future (IOF) strategy within the Office of Industrial Technologies (OIT) and the scheduled completion of the Continuous Fiber Ceramic Composites (CFCC) Program in FY 2002, an integrated materials program is being developed in OIT. So this represents the last summary of AIM research and development. The new program, Industrial Materials for the Future (IMF), will be competitive in operation, with solicitations for proposals for development of materials in accordance with the IOF Technology Roadmaps, followed by merit review and funding of the best proposals. Industry will take the lead in ''industry-specific'' research and development, in cooperation with National Laboratories, as needed. National Laboratories and universities will take the lead in maintaining a base technology program, for the purpose of maintaining a continuing flow of new materials technologies. The AIM and CFCC Programs will be replaced by the IMF program over a three year period, so that in FY 2004, all research and development will be in response to industry solicitations and Laboratory/university calls. The Program Manager believes that AIM has been an extremely successful program, thanks to the Laboratory investigators and their partners. For 10 years, the program has increased industrial participation from very little to nearly 100 percent. The CFCC Program, similarly, has been successful in advancing the knowledge of processing and property development in these materials, though much still can be done in advancing their uses ...
Date: August 8, 2000
Creator: Angelini, P
Partner: UNT Libraries Government Documents Department

Improvements in bis(cyclopentadienyl)magnesium purity as determined with gas chromatography-mass spectroscopy

Description: Bis(cyclopentadienyl)magnesium (MgCp2) is used commonly as a source for doping nitride materials with magnesium. Increased oxygen incorporation known to accompany the use of MgCp2 makes the purity of this precursor an important consideration in nitride CVD. Gas chromatography-mass spectroscopy (GCMS) methods have now been developed for the identification of volatile impurities in MgCp2. Diethylether, an oxygen containing organic compound (CH{sub 3}CH{sub 2}OCH{sub 2}CH{sub 3}), and additional organic impurities were found in the MgCp2 supplied by three manufacturers. Subsequent refinements in the synthetic processes by these companies have resulted in the availability of MgCp2 free of ether and other organic impurities as determined by GCMS.
Date: March 8, 2000
Creator: BARTRAM,MICHAEL E.
Partner: UNT Libraries Government Documents Department

Recent plant studies using Victoria 2.0

Description: VICTORIA 2.0 is a mechanistic computer code designed to analyze fission product behavior within the reactor coolant system (RCS) during a severe nuclear reactor accident. It provides detailed predictions of the release of radioactive and nonradioactive materials from the reactor core and transport and deposition of these materials within the RCS and secondary circuits. These predictions account for the chemical and aerosol processes that affect radionuclide behavior. VICTORIA 2.0 was released in early 1999; a new version VICTORIA 2.1, is now under development. The largest improvements in VICTORIA 2.1 are connected with the thermochemical database, which is being revised and expanded following the recommendations of a peer review. Three risk-significant severe accident sequences have recently been investigated using the VICTORIA 2.0 code. The focus here is on how various chemistry options affect the predictions. Additionally, the VICTORIA predictions are compared with ones made using the MELCOR code. The three sequences are a station blackout in a GE BWR and steam generator tube rupture (SGTR) and pump-seal LOCA sequences in a 3-loop Westinghouse PWR. These sequences cover a range of system pressures, from fully depressurized to full system pressure. The chief results of this study are the fission product fractions that are retained in the core, RCS, secondary, and containment and the fractions that are released into the environment.
Date: March 8, 2000
Creator: BIXLER,NATHAN E. & GASSER,RONALD D.
Partner: UNT Libraries Government Documents Department

Effects of Fire on Soil Seed Banks on the Hanford Site

Description: The Hanford wildfire in the summer of 2000 destroyed much of the vegetation on the Hanford Site, often resulting in soil erosion and dust storms. The 200 W Area has been affected by dust storms, and a re-vegetation project has been planned for the area to the west, the source of much of the dust. To determine if the seed bank in this area had been damaged by the fire, inhibiting natural re-growth, soil samples were collected from three burned areas and watered to see how much seedling emergence would occur. The soil was then sifted for grass seeds and the seeds examined for signs of fire damage. From this data it was concluded that significant damage to the seed bank probably occurred in the 200 West Expansion Area, and slight damage may have occurred primarily to monocot seeds in the seed banks farther west.
Date: September 8, 2000
Creator: Baker, Sarah E.
Partner: UNT Libraries Government Documents Department

Imaging System for the Automated Determination of Microscopical Properties in Hardened Portland Concrete

Description: During this CRADA, Honeywell FM and T and MoDOT personnel designed a unique scanning system (including both hardware and software) that can be used to perform an automated scan and evaluation of a concrete sample. The specific goals of the CRADA were: (1) Develop a combined system integration, image acquisition, and image analysis approach to mimic the manual scanning and evaluation process. Produce a prototype system which can: (a) automate the scanning process to improve its speed and efficiency; (b) reduce operator fatigue; and (c) improve the consistency of the evaluation process. (2) Capture and preserve the baseline knowledge used by the MoDOT experts in performing the evaluation process. At the present time, the evaluation expertise resides in two MoDOT personnel. Automation of the evaluation process will allow that knowledge to be captured, preserved, and used for training purposes. (3) Develop an approach for the image analysis which is flexible and extensible in order to accommodate the inevitable pathologies that arise in the evaluation process. Such pathologies include features such as cracks and fissures, voids filled with paste or debris, and multiple, overlapping voids. FM and T personnel used image processing, pattern recognition, and system integration skills developed for other Department of Energy applications to develop and test a prototype of an automated scanning system for concrete evaluation. MoDOT personnel provided all the basic hardware (microscope, camera, computer-controlled stage, etc.) for the prototype, supported FM and T in the acquisition of image data for software development, and provided their critical expert knowledge of the process of concrete evaluation. This combination of expertise was vital to the successful development of the prototype system.
Date: March 8, 2000
Creator: Baumgart, C.W.; Cave, S.P. & Linder, K.E.
Partner: UNT Libraries Government Documents Department

Development of field portable sampling and analysis systems

Description: A rapid field portable sample and analysis system has been demonstrated at the Savannah River Site and the Hanford Site. The portable system can be used when rapid decisions are needed in the field during scoping or remediation activities, or when it is impractical to bring large volumes of water to the lab for analysis.
Date: June 8, 2000
Creator: Beals, D.
Partner: UNT Libraries Government Documents Department

Defect diffusion during annealing of low-energy ion-implanted silicon

Description: We present a new approach for investigating the kinetics of defect migration during annealing of low-energy, ion-implanted silicon, employing a combination of computer simulations and atomic-resolution tunneling microscopy. Using atomically-clean Si(111)-7x7 as a sink for bulk point defects created by 5 keV Xe and Ar irradiation, we observe distinct, temperature-dependent surface arrival rates for vacancies and interstitials. A combination of simulation tools provides a detailed description of the processes that underly the observed temperature-dependence of defect segregation, and the predictions of the simulations agree closely with the experimental observations.
Date: March 8, 2000
Creator: Bedrossian, P J; Caturla, M-J & Diaz de la Rubia, T
Partner: UNT Libraries Government Documents Department

Uncharted Frontiers in the Spectroscopy of Highly Charged Ions

Description: The development of novel techniques is critical for maintaining a state-of-the-art core competency in atomic physics and readiness for evolving programmatic needs. We have carried out a three-year effort to develop novel spectroscopic instrumentation that added new dimensions to our capabilities for measuring energy levels, radiative transition probabilities, and electron-ion excitation processes. The new capabilities created were in areas that heretofore had been inaccessible to scientific scrutiny and included high-resolution spectroscopy of hard x rays, femtosecond lifetime measurements, measurements of transition probabilities of long-lived metastable levels, polarization spectroscopy, ultra-precise determinations of energy levels, and the establishment of absolute wavelength standards in x-ray spectroscopy. Instrumentation developed during the period included a transmission-type crystal spectrometer, a flat-field EUV spectrometer, and the development and deployment of absolutely calibrated monolithic crystals. The new capabilities enabled very sensitive tests of atomic wave functions, of calculations of magnetic sublevel populations, and of fundamental theories in uncharted regimes, and provided the basis for developing new diagnostic techniques of high-density plasmas.
Date: January 8, 2000
Creator: Beiersdorfer, P.; Brown, G.; Crespo, J.; Kim, S.-H.; Neill, P.; Utter, S. et al.
Partner: UNT Libraries Government Documents Department

AH-1Z First Flight

Description: First flight of the AH-1Z Viper attack helicopter. The aircraft performs an extended hover before landing.
Date: December 8, 2000
Creator: Bell Helicopter Textron
Partner: UNT Libraries Special Collections

Evidence for competing order parameters in the paramagnetic phase of layered manganites.

Description: The magnetic field and temperature dependence of the magnetic susceptibility and magnetization is studied for the ferromagnetic layered manganites SrO(La{sub t{minus}x}Sr{sub x}MnO{sub 3}){sub 2} in the composition range x = 0.32-0.40. In the paramagnetic phase, the susceptibility exhibits an anomalous maximum at an intermediate magnetic field value. The size of this field-induced susceptibility enhancement increases dramatically with x from 10% for x = 0.32 to 160% for x = 0.40. The temperature dependence of the effect shows a maximum at T {approx} 1.1 T{sub c} for all x. Quantitative analysis in terms of the Landau theory of phase transitions enables us to identify a distortion of the free energy F in the paramagnetic phase that is associated with the susceptibility anomaly. This free energy distortion corresponds to a magnetic system that approaches a first order magnetic phase transition as the temperature is lowered towards T{sub c}. Such a behavior is indicative of a second, competing order parameter, which is identified as the recently observed charge density wave. In the immediate vicinity of T{sub c}, the anomaly disappears and the system seems to undergo a more conventional second order paramagnetic-ferromagnetic phase transition.
Date: November 8, 2000
Creator: Berger, A.; Mitchell, J. F.; Miller, D. J. & Bader, S. D.
Partner: UNT Libraries Government Documents Department

Longitudinal spin dependence of massive lepton pair production

Description: In this paper, the authors summarize recent work in which they demonstrate that the Compton subprocess, q + g {r_arrow} {gamma}* + q also dominates the Drell-Yan cross section in polarized and unpolarized proton-proton reactions for values of the transverse momentum Q{sub T} of the pair that are larger than roughly half of the pair mass Q, Q{sub T} > Q/2. The Drell-Yan process is therefore a valuable, heretofore overlooked, independent source of constraints on the spin-averaged and spin-dependent gluon densities. Although the Drell-Yan cross section is smaller than the prompt photon cross section, massive lepton pair production is cleaner theoretically since long-range fragmentation contributions are absent as are the experimental and theoretical complications associated with isolation of the real photon. Moreover, the dynamics of spin-dependence in hard-scattering processes is a sufficiently complex topic, and its understanding at an early stage in its development, that several defensible approaches for extracting polarized parton densities deserve to be pursued with the expectation that consistent results must emerge.
Date: February 8, 2000
Creator: Berger, E. L.; Gordon, L. E. & Klasen, M.
Partner: UNT Libraries Government Documents Department

Quench sensitivity of hot extruded 6061-T6 and 6069-T6 aluminum alloys

Description: The purpose of this study is to investigate the quench sensitivity of mechanical properties of hot extruded 6061 and 6069 aluminum alloys. The relationship between mechanical properties and quench delzty time at various temperatures between 200-500 C was determined. It was concluded that the 6069-T6 was somewhat more quench sensitive than 6061, which may be consistent with the composition difference.
Date: August 8, 2000
Creator: Bergsma, S C; Kassner, M E; Li, X & Rosen, R S
Partner: UNT Libraries Government Documents Department

Microrelay

Description: Our goals in this project were to (1) develop a new design concept for a high reliability microrelay, (2) build a prototype, and (3) demonstrate high force relay closure in the prototype. During FY1999, we designed a microrelay to meet commercial specifications: 3 g (or 0.03 N) closure force and 30-mA actuation current at less than 0.5 V. Our microrelay not only occupies less than 1 mm{sup 3}--about 1% of the volume of the smallest commercial part--but also its fabrication takes advantage of semiconductor processing, which has the potential to automate microrelay production. Conventional relays are fabricated by assembling many discrete parts. The process includes a number of nonautomated assembly and inspection steps, which increase fabrication cost and limit possible size reductions. Microrelays based on electrostatic forces can be fabricated by thin-film techniques employed in the semiconductor industry; however, the voltages required to make reliable electrical contact in an electrostatic relay significantly increase the cost of the driver. Microrelays based on electromagnetic forces, on the other hand, provide reliable contacts at low voltage. Reliable metal-to-metal contacts require sufficient contact force to plastically deform contact surfaces at asperities-thereby increasing the contact area. On the other hand, contact metallurgy and the gaseous environment must be controlled to prevent contact welding, contamination, oxidation, and other effects that change contact resistance over time. A contact force of 3 g is commonly used with gold/gold-alloy contacts in a sealed relay (e.g., a reed relay). In this way, more than 10 million closures can be achieved with a resistance of less than 100 m{Omega}. Our prototype relay preserves the contact metallurgy of commercial relays. The fundamental innovation in the fabrication of our microrelay is the use of a 3-D lithographic process to create a ''winding'' around a discrete magnetic core. To achieve sufficient inductance to generate ...
Date: September 8, 2000
Creator: Bernhardt, A; Cooper, G & Malba, V
Partner: UNT Libraries Government Documents Department

Formation and Reactivity of Biogenic Iron Microminerals

Description: The overall purpose of the project is to explore and quantify the processes that control the formation and reactivity of biogenic iron microminerals and their impact on the solubility of metal contaminants. The research addresses how surface components of bacterial cells, extracellular organic material, and the aqueous geochemistry of the DIRB microenvironment impacts the mineralogy, chemical state and micromorphology of reduced iron phases.
Date: August 8, 2000
Creator: Beveridge, Terrance J.; Glasauer, Susan; Korenevsky, Anton & Ferris, F. Grant
Partner: UNT Libraries Government Documents Department