Pressure-induced isostructural transition in PdN2 (open access)

Pressure-induced isostructural transition in PdN2

We show that a synthesized Pd-N compound crystallize into the pyrite structure by comparison of experimental and calculated Raman intensities. The decreasing Raman intensities with decreasing pressure is explained by a closing of the fundamental band gap. We further discuss the experimental decomposition of this compound at 11 GPa in terms of an isostructural transition within the pyrite structure.
Date: March 5, 2010
Creator: Aberg, D; Erhart, P; Crowhurst, J; Zaug, J M; Goncharov, A F & Sadigh, B
Object Type: Article
System: The UNT Digital Library
Attrition Resistant Fischer-Tropsch Catalysts Based on FCC Supports (open access)

Attrition Resistant Fischer-Tropsch Catalysts Based on FCC Supports

Commercial spent fluid catalytic cracking (FCC) catalysts provided by Engelhard and Albemarle were used as supports for Fe-based catalysts with the goal of improving the attrition resistance of typical F-T catalysts. Catalysts with the Ruhrchemie composition (100 Fe/5 Cu/4.2 K/25 spent FCC on mass basis) were prepared by wet impregnation. XRD and XANES analysis showed the presence of Fe{sub 2}O{sub 3} in calcined catalysts. FeC{sub x} and Fe{sub 3}O{sub 4} were present in the activated catalysts. The metal composition of the catalysts was analyzed by ICP-MS. F-T activity of the catalysts activated in situ in CO at the same conditions as used prior to the attrition tests was measured using a fixed bed reactor at T = 573 K, P = 1.38 MPa and H{sub 2}:CO ratio of 0.67. Cu and K promoted Fe supported over Engelhard provided spent FCC catalyst shows relatively good attrition resistance (8.2 wt% fines lost), high CO conversion (81%) and C{sub 5}+ hydrocarbons selectivity (18.3%).
Date: February 5, 2010
Creator: Adeyiga, Adeyinka
Object Type: Report
System: The UNT Digital Library
Gene by Disease Interaction on Orbitofrontal Gray Matter in Cocaine Addiction (open access)

Gene by Disease Interaction on Orbitofrontal Gray Matter in Cocaine Addiction

Chronic cocaine use has been associated with structural deficits in brain regions having dopamine receptive neurons. However, the concomitant use of other drugs and common genetic variability in monoamine regulation present additional structural variability. We therefore examined variations in gray matter volume (GMV) as a function of lifetime drug use and the monoamine oxidase A (MAOA) genotype in cocaine use disorders (CUD) and healthy controls.
Date: December 5, 2010
Creator: Alia-Klein, N.; Alia-Klein, N.; Parvaz, M. A.; Woicik, P. A.; Konova, A.; Maloney, T. et al.
Object Type: Article
System: The UNT Digital Library
The FERMI@Elettra free-electron-laser source for coherent X-ray physics: photon properties, beam transport system, and applications (open access)

The FERMI@Elettra free-electron-laser source for coherent X-ray physics: photon properties, beam transport system, and applications

FERMI@Elettra is comprised of two free electron lasers (FELs) that will generate short pulses (tau ~;; 25 to 200 fs) of highly coherent radiation in the XUV and soft X-ray region. The use of external laser seeding together with a harmonic upshift scheme to obtain short wavelengths will give FERMI@Elettra the capability to produce high quality, longitudinal coherent photon pulses. This capability together with the possibilities of temporal synchronization to external lasers and control of the output photon polarization will open new experimental opportunities not possible with currently available FELs. Here we report on the predicted radiation coherence properties and important configuration details of the photon beam transport system. We discuss the several experimental stations that will be available during initial operations in 2011, and we give a scientific perspective on possible experiments that can exploit the critical parameters of this new light source.
Date: April 5, 2010
Creator: Allaria, Enrico; Callegari, Carlo; Cocco, Daniele; Fawley, William M.; Kiskinova, Maya; Masciovecchio, Claudio et al.
Object Type: Article
System: The UNT Digital Library
Paleoclimatic implications of glacial and postglacial refugia for Pinus pumila in western Beringia (open access)

Paleoclimatic implications of glacial and postglacial refugia for Pinus pumila in western Beringia

Palynological results from Julietta Lake currently provide the most direct evidence to support the existence of a glacial refugium for Pinus pumila in mountains of southwestern Beringia. Both percentages and accumulation rates indicate the evergreen shrub survived until at least {approx}19,000 14C yr B.P. in the Upper Kolyma region. Percentage data suggest numbers dwindled into the late glaciation, whereas pollen accumulation rates point towards a more rapid demise shortly after {approx}19,000 14C yr B.P. Pinus pumila did not re-establish in any great numbers until {approx}8100 14C yr B.P., despite the local presence {approx}9800 14C yr B.P. of Larix dahurica, which shares similar summer temperature requirements. The postglacial thermal maximum (in Beringia {approx}11,000-9000 14C yr B.P.) provided Pinus pumila shrubs with equally harsh albeit different conditions for survival than those present during the LGM. Regional records indicate that in this time of maximum warmth Pinus pumila likely sheltered in a second, lower-elevation refugium. Paleoclimatic models and modern ecology suggest that shifts in the nature of seasonal transitions and not only seasonal extremes have played important roles in the history of Pinus pumila over the last {approx}21,000 14C yr B.P.
Date: February 5, 2010
Creator: Anderson, P M; Lozhkin, A V; Solomatkina, T B & Brown, T A
Object Type: Article
System: The UNT Digital Library
The European Parliament (open access)

The European Parliament

The European Parliament (EP) is one of the three key institutions of the European Union (EU), and the only EU institution whose members are directly elected. This report discusses the construction and history of the EP, its role in functions of the EU as well as internationally, various international supports and criticisms of the EP, and the EP's ties with the U.S. Congress.
Date: November 5, 2010
Creator: Archick, Kristin & Mix, Derek E.
Object Type: Report
System: The UNT Digital Library
The European Union: Questions and Answers (open access)

The European Union: Questions and Answers

This report provides a brief overview of the European Union (EU), an economic and political partnership between 27 sovereign member states. The report describes the formation of the EU, the three main institutions of the EU, and the EU's relationship with the United States.
Date: November 5, 2010
Creator: Archick, Kristin & Mix, Derek E.
Object Type: Report
System: The UNT Digital Library
Terrestrial biogeochemical feedbacks in the climate system: from past to future (open access)

Terrestrial biogeochemical feedbacks in the climate system: from past to future

The terrestrial biosphere plays a major role in the regulation of atmospheric composition, and hence climate, through multiple interlinked biogeochemical cycles (BGC). Ice-core and other palaeoenvironmental records show a fast response of vegetation cover and exchanges with the atmosphere to past climate change, although the phasing of these responses reflects spatial patterning and complex interactions between individual biospheric feedbacks. Modern observations show a similar responsiveness of terrestrial biogeochemical cycles to anthropogenically-forced climate changes and air pollution, with equally complex feedbacks. For future conditions, although carbon cycle-climate interactions have been a major focus, other BGC feedbacks could be as important in modulating climate changes. The additional radiative forcing from terrestrial BGC feedbacks other than those conventionally attributed to the carbon cycle is in the range of 0.6 to 1.6 Wm{sup -2}; all taken together we estimate a possible maximum of around 3 Wm{sup -2} towards the end of the 21st century. There are large uncertainties associated with these estimates but, given that the majority of BGC feedbacks result in a positive forcing because of the fundamental link between metabolic stimulation and increasing temperature, improved quantification of these feedbacks and their incorporation in earth system models is necessary in order to develop …
Date: January 5, 2010
Creator: Arneth, A.; Harrison, S. P.; Zaehle, S.; Tsigaridis, K.; Menon, S.; Bartlein, P. J. et al.
Object Type: Article
System: The UNT Digital Library
Heavy Water Components Test Reactor Decommissioning - Major Component Removal (open access)

Heavy Water Components Test Reactor Decommissioning - Major Component Removal

The Heavy Water Components Test Reactor (HWCTR) facility (Figure 1) was built in 1961, operated from 1962 to 1964, and is located in the northwest quadrant of the Savannah River Site (SRS) approximately three miles from the site boundary. The HWCTR facility is on high, well-drained ground, about 30 meters above the water table. The HWCTR was a pressurized heavy water test reactor used to develop candidate fuel designs for heavy water power reactors. It was not a defense-related facility like the materials production reactors at SRS. The reactor was moderated with heavy water and was rated at 50 megawatts thermal power. In December of 1964, operations were terminated and the facility was placed in a standby condition as a result of the decision by the U.S. Atomic Energy Commission to redirect research and development work on heavy water power reactors to reactors cooled with organic materials. For about one year, site personnel maintained the facility in a standby status, and then retired the reactor in place. In 1965, fuel assemblies were removed, systems that contained heavy water were drained, fluid piping systems were drained, deenergized and disconnected and the spent fuel basin was drained and dried. The doors of …
Date: May 5, 2010
Creator: Austin, W. & Brinkley, D.
Object Type: Article
System: The UNT Digital Library
Applying Human Factors during the SIS Life Cycle (open access)

Applying Human Factors during the SIS Life Cycle

Safety Instrumented Systems (SIS) are widely used in U.S. Department of Energy's (DOE) nonreactor nuclear facilities for safety-critical applications. Although use of the SIS technology and computer-based digital controls, can improve performance and safety, it potentially introduces additional complexities, such as failure modes that are not readily detectable. Either automated actions or manual (operator) actions may be required to complete the safety instrumented function to place the process in a safe state or mitigate a hazard in response to an alarm or indication. DOE will issue a new standard, Application of Safety Instrumented Systems Used at DOE Nonreactor Nuclear Facilities, to provide guidance for the design, procurement, installation, testing, maintenance, operation, and quality assurance of SIS used in safety significant functions at DOE nonreactor nuclear facilities. The DOE standard focuses on utilizing the process industry consensus standard, American National Standards Institute/ International Society of Automation (ANSI/ISA) 84.00.01, Functional Safety: Safety Instrumented Systems for the Process Industry Sector, to support reliable SIS design throughout the DOE complex. SIS design must take into account human-machine interfaces and their limitations and follow good human factors engineering (HFE) practices. HFE encompasses many diverse areas (e.g., information display, user-system interaction, alarm management, operator response, control …
Date: May 5, 2010
Creator: Avery, K.
Object Type: Article
System: The UNT Digital Library
Energy and Water Development: FY2010 Appropriations (open access)

Energy and Water Development: FY2010 Appropriations

This report discusses the Energy and Water Development appropriations bill that provides funding for civil works projects of the Army Corps of Engineers (Corps), for the Department of the Interior's Bureau of Reclamation (Reclamation), the Department of Energy (DOE), and several independent agencies.
Date: January 5, 2010
Creator: Behrens, Carl E.
Object Type: Report
System: The UNT Digital Library
Fighting Fire with Fire: Superlattice Cooling of Silicon Hotspots to Reduce Global Cooling Requirements (open access)

Fighting Fire with Fire: Superlattice Cooling of Silicon Hotspots to Reduce Global Cooling Requirements

The running costs of data centers are dominated by the need to dissipate heat generated by thousands of server machines. Higher temperatures are undesirable as they lead to premature silicon wear-out; in fact, mean time to failure has been shown to decrease exponentially with temperature (Black's law). Although other server components also generate heat, microprocessors still dominate in most server configurations and are also the most vulnerable to wearout as the feature sizes shrink. Even as processor complexity and technology scaling have increased the average energy density inside a processor to maximally tolerable levels, modern microprocessors make extensive use of hardware structures such as the load-store queue and other CAM-based units, and the peak temperatures on chip can be much worse than even the average temperature of the chip. In recent studies, it has been shown that hot-spots inside a processor can generate {approx} 800W/cm{sup 2} heat flux whereas the average heat flux is only 10-50W/cm{sup 2}, and due to this disparity in heat generation, the temperature in hot spots may be up to 30 C more than average chip temperature. The key problem processor hot-spots create is that in order to prevent some critical hardware structures from wearing out …
Date: October 5, 2010
Creator: Biswas, S; Tiwari, M; Sherwood, T; Theogarajan, L & Chong, F T
Object Type: Article
System: The UNT Digital Library
Qatar: Background and U.S. Relations (open access)

Qatar: Background and U.S. Relations

This report presents an overview of Qatar's history and recent economic and political developments. The report discusses U.S. relations with Qatar, U.S. military cooperation and foreign assistance, political reform and elections, as well as human rights and social issues.
Date: May 5, 2010
Creator: Blanchard, Christopher M.
Object Type: Report
System: The UNT Digital Library
The U.N. Convention on the Elimination of All Forms of Discrimination Against Women (CEDAW): Issues in the U.S. Ratification Debate (open access)

The U.N. Convention on the Elimination of All Forms of Discrimination Against Women (CEDAW): Issues in the U.S. Ratification Debate

This report provides an overview of the Convention on the Elimination of All Forms of Discrimination Against Women (CEDAW) and describes its background, objectives, and structure, including the role of the Convention's monitoring body, the CEDAW Committee. It examines U.S. policy and issues in the U.S. ratification debate, including the Convention's possible impact on U.S. sovereignty, its effectiveness in combating discrimination, and its role as an instrument of U.S. foreign policy.
Date: May 5, 2010
Creator: Blanchfield, Luisa
Object Type: Report
System: The UNT Digital Library
Greenhouse Gas Emission Drivers: Population, Economic Development and Growth, and Energy Use (open access)

Greenhouse Gas Emission Drivers: Population, Economic Development and Growth, and Energy Use

The interactions of three variables underlie debates on the issue of climate change and what responses might be justified: the magnitude and rates of change of (1) population growth, (2) incomes, and (3) intensity of greenhouse gas emissions relative to economic activities. This report examines the interrelationships of the variables to explore their implications for policies that address climate change.
Date: March 5, 2010
Creator: Blodgett, John & Parker, Larry
Object Type: Report
System: The UNT Digital Library
Preliminary Evaluation of the Section 1603 Treasury Grant Program for Renewable Power Projects in the United States (open access)

Preliminary Evaluation of the Section 1603 Treasury Grant Program for Renewable Power Projects in the United States

This article evaluates the first year of the Section 1603 Treasury cash grant program, which enables renewable power projects in the U.S. to elect cash grants in lieu of the federal tax credits that are otherwise available. To date, the program has been heavily subscribed, particularly by wind power projects, which had received 86% of the nearly $2.6 billion in grants that had been disbursed as of March 1, 2010. As of that date, 6.2 GW of the 10 GW of new wind capacity installed in the U.S. in 2009 had applied for grants in lieu of production tax credits. Roughly 2.4 GW of this wind capacity may not have otherwise been built in 2009 absent the grant program; this 2.4 GW may have supported approximately 51,600 short-term full-time-equivalent (FTE) gross job-years in the U.S. during the construction phase of these wind projects, and 3,860 longterm FTE gross jobs during the operational phase. The program’s popularity stems from the significant economic value that it provides to renewable power projects, relative to the otherwise available tax credits. Although grants reward investment rather than efficient performance, this evaluation finds no evidence at this time of either widespread “gold-plating” or performance problems.
Date: May 5, 2010
Creator: Bolinger, Mark; Wiser, Ryan & Darghouth, Naim
Object Type: Article
System: The UNT Digital Library
Proposed U.S.-Colombia Free Trade Agreement: Labor Issues (open access)

Proposed U.S.-Colombia Free Trade Agreement: Labor Issues

This report examines three labor issues and arguments related to the pending U.S.-Colombia free trade agreement (CFTA; H.R. 5724 and S. 2830): violence against trade unionists; impunity (accountability for or punishment of the perpetrators); and worker rights protections for Colombians.
Date: October 5, 2010
Creator: Bolle, Mary Jane
Object Type: Report
System: The UNT Digital Library
Eastern Equine Encephalitis Virus (open access)

Eastern Equine Encephalitis Virus

None
Date: August 5, 2010
Creator: Borucki, M
Object Type: Report
System: The UNT Digital Library
Task 1.5 Genomic Shift and Drift Trends of Emerging Pathogens (open access)

Task 1.5 Genomic Shift and Drift Trends of Emerging Pathogens

The Lawrence Livermore National Laboratory (LLNL) Bioinformatics group has recently taken on a role in DTRA's Transformation Medical Technologies Initiative (TMTI). The high-level goal of TMTI is to accelerate the development of broad-spectrum countermeasures. To achieve those goals, TMTI has a near term need to conduct analyses of genomic shift and drift trends of emerging pathogens, with a focused eye on select agent pathogens, as well as antibiotic and virulence markers. Most emerging human pathogens are zoonotic viruses with a genome composed of RNA. The high mutation rate of the replication enzymes of RNA viruses contributes to sequence drift and provides one mechanism for these viruses to adapt to diverse hosts (interspecies transmission events) and cause new human and zoonotic diseases. Additionally, new viral pathogens frequently emerge due to genetic shift (recombination and segment reassortment) which allows for dramatic genotypic and phenotypic changes to occur rapidly. Bacterial pathogens also evolve via genetic drift and shift, although sequence drift generally occurs at a much slower rate for bacteria as compared to RNA viruses. However, genetic shift such as lateral gene transfer and inter- and intragenomic recombination enables bacteria to rapidly acquire new mechanisms of survival and antibiotic resistance. New technologies such …
Date: January 5, 2010
Creator: Borucki, M
Object Type: Report
System: The UNT Digital Library
Progress Towards Deployable Antineutrino Detectors for Reactor Safeguards (open access)

Progress Towards Deployable Antineutrino Detectors for Reactor Safeguards

Fission reactors emit large numbers of antineutrinos and this flux may be useful for the measurement of two quantities of interest for reactor safeguards: the reactor's power and plutonium inventory throughout its cycle. The high antineutrino flux and relatively low background rates means that simple cubic meter scale detectors at tens of meters standoff can record hundreds or thousands of antineutrino events per day. Such antineutrino detectors would add online, quasi-real-time bulk material accountancy to the set of reactor monitoring tools available to the IAEA and other safeguards agencies with minimal impact on reactor operations. Between 2003 and 2008, our LLNL/SNL collaboration successfully deployed several prototype safeguards detectors at a commercial reactor in order to test both the method and the practicality of its implementation in the field. Partially on the strength of the results obtained from these deployments, an Experts Meeting was convened by the IAEA Novel Technologies Group in 2008 to assess current antineutrino detection technology and examine how it might be incorporated into the safeguards regime. Here we present a summary of our previous deployments and discuss current work that seeks to provide expanded capabilities suggested by the Experts Panel, in particular aboveground detector operation.
Date: April 5, 2010
Creator: Bowden, N; Bernstein, A; Dazeley, S; Keefer, G; Reyna, D; Cabrera-Palmer, B et al.
Object Type: Article
System: The UNT Digital Library
Control of Toxic Chemicals in Puget Sound, Phase 3: Study of Atmospheric Deposition of Air Toxics to the Surface of Puget Sound (open access)

Control of Toxic Chemicals in Puget Sound, Phase 3: Study of Atmospheric Deposition of Air Toxics to the Surface of Puget Sound

The results of the Phase 1 Toxics Loading study suggested that runoff from the land surface and atmospheric deposition directly to marine waters have resulted in considerable loads of contaminants to Puget Sound (Hart Crowser et al. 2007). The limited data available for atmospheric deposition fluxes throughout Puget Sound was recognized as a significant data gap. Therefore, this study provided more recent or first reported atmospheric deposition fluxes of PAHs, PBDEs, and select trace elements for Puget Sound. Samples representing bulk atmospheric deposition were collected during 2008 and 2009 at seven stations around Puget Sound spanning from Padilla Bay south to Nisqually River including Hood Canal and the Straits of Juan de Fuca. Revised annual loading estimates for atmospheric deposition to the waters of Puget Sound were calculated for each of the toxics and demonstrated an overall decrease in the atmospheric loading estimates except for polybrominated diphenyl ethers (PBDEs) and total mercury (THg). The median atmospheric deposition flux of total PBDE (7.0 ng/m2/d) was higher than that of the Hart Crowser (2007) Phase 1 estimate (2.0 ng/m2/d). The THg was not significantly different from the original estimates. The median atmospheric deposition flux for pyrogenic PAHs (34.2 ng/m2/d; without TCB) shows …
Date: July 5, 2010
Creator: Brandenberger, Jill M.; Louchouarn, Patrick; Kuo, Li-Jung; Crecelius, Eric A.; Cullinan, Valerie I.; Gill, Gary A. et al.
Object Type: Report
System: The UNT Digital Library
Layed Perovskite PRBA0.5SR0.5CO205 as High Performance Cathode for Solid Oxide Fuels Using Photon Conducting Electrolyte (open access)

Layed Perovskite PRBA0.5SR0.5CO205 as High Performance Cathode for Solid Oxide Fuels Using Photon Conducting Electrolyte

The layered perovskite PrBa{sub 0.5}Sr{sub 0.5}Co{sub 2}O{sub 5+{delta}} (PBSC) was investigated as a cathode material for a solid oxide fuel cell using a proton-conducting electrolyte based on BaCe{sub 0.7}Y{sub 0.2}Zr{sub 0.1}O{sub 3-{delta}} (BCYZ). The sintering conditions for the PBSC-BCYZ composite cathode were optimized resulting in the lowest area-specific resistance and apparent activation energy obtained with the cathode sintered at 1200 C for 2h. The maximum power densities of the PBSC-BCYZ/BZCY/NiO-BCYZ cell were 0.179, 0.274, 0.395, and 0.522 Wcm{sup -2} at 550, 600, 650, and 700 C, respectively with a 15{micro}m thick electrolyte. A relatively low cell interfacial polarization resistance of 0.132 {Omega}cm{sup 2} at 700 C indicated that the PBSC-BCYZ could be a good cathode candidate for intermediate temperature SOFCs with proton-conducting electrolyte.
Date: May 5, 2010
Creator: Brinkman, K.
Object Type: Article
System: The UNT Digital Library
Visualization and Analysis-Oriented Reconstruction of Material Interfaces (open access)

Visualization and Analysis-Oriented Reconstruction of Material Interfaces

Reconstructing boundaries along material interfaces from volume fractions is a difficult problem, especially because the under-resolved nature of the input data allows for many correct interpretations. Worse, algorithms widely accepted as appropriate for simulation are inappropriate for visualization. In this paper, we describe a new algorithm that is specifically intended for reconstructing material interfaces for visualization and analysis requirements. The algorithm performs well with respect to memory footprint and execution time, has desirable properties in various accuracy metrics, and also produces smooth surfaces with few artifacts, even when faced with more than two materials per cell.
Date: March 5, 2010
Creator: Childs, Henry R.
Object Type: Article
System: The UNT Digital Library
Nano Vacancy Clusters and Trap Limited Diffusion of Si Interstitials in Silicon (open access)

Nano Vacancy Clusters and Trap Limited Diffusion of Si Interstitials in Silicon

The objective of this project is to develop a method to characterize nano vacancy clusters and the dynamics of their formation in ion-irradiated silicon. It will impact (1) semiconductor device processing involving ion implantation, and (2) device design concerning irradiation hardness in harsh environments. It also aims to enhance minority participation in research and curricula on emerging materials and ion beam science. Vacancy defects are of scientific and technological importance since they are ubiquitous when the host materials are exposed to particle irradiation. Studies on vacancy clustering in the past decades were mainly theoretical and the approach heavily relied on the total-energy calculation methods. The lack of experimental data is mainly due to the formidable task in measuring the cluster size and density using modern metrological techniques, including transmission electron microscopy and positron annihilation spectroscopy. To surmount these challenges, we proposed a novel approach to tackle the metrological problems on the nano vacancy clusters, especially in determining densities and sizes of the nano vacancies based on the premise that the vacancy-clusters act as diffusion-trapping centers. For a silicon substrate containing vacancyclusters, the diffusion of interstitials (from the surface) can be classified into three phases: (1) an ultrafast phase-I in which …
Date: May 5, 2010
Creator: Chu, Prof. Wei-Kan
Object Type: Report
System: The UNT Digital Library