Tuning electronic properties of novel metal oxide nanocrystals using interface interactions: MoO3 monolayers on Au(111) (open access)

Tuning electronic properties of novel metal oxide nanocrystals using interface interactions: MoO3 monolayers on Au(111)

Metal oxide nanocrystals deposited on metal surfaces have novel electronic properties due to interface and nanoscale effects. Crystals and nanoscale ribbons of MoO{sub 3} are highly effective catalysts and field emitters. This renders MoO{sub 3} an interesting prototype. Whilst MoO{sub 3} exists as bilayers in the bulk crystal5, in this work, monolayer MoO{sub 3} nanocrystals were grown epitaxially on Au(111). Ab initio calculations reveal that Au stabilizes the MoO{sub 3} monolayer through electronic charge redistribution at the interface. The Mo-O bonds are able to rotate about one another, allowing the MoO{sub 3} monolayer to adjust to the Au lattice. As a result, the monolayer is semimetallic, unlike bulk MoO{sub 3} which is semiconducting. This remarkable flexibility of the oxide lattice suggests the possibility of tuning electronic properties of transition metal oxides via interface interactions. The overall surface pattern obtained is affected by an interplay between the Au(111) surface reconstruction and the edges of the deposited MoO{sub 3} islands.
Date: April 20, 2004
Creator: Quek, S; Biener, M M; Biener, J; Friend, C M & Kaxiras, E
Object Type: Article
System: The UNT Digital Library
Convex Crystal X-ray Spectrometer for Laser Plasma Experiments (open access)

Convex Crystal X-ray Spectrometer for Laser Plasma Experiments

Measuring time and space-resolved spectra is important for understanding Hohlraum and Halfraum plasmas. Experiments at the OMEGA laser have used the Nova TSPEC which was not optimized for the OMEGA diagnostic space envelope or for the needed spectroscopic coverage and resolution. An improved multipurpose spectrometer snout, the MSPEC, has been constructed and fielded on OMEGA. The MSPEC provides the maximal internal volume for mounting crystals without any beam interferences at either 2x or 3x magnification. The RAP crystal is in a convex mounting geometry bent to a 20 cm radius of curvature. The spectral resolution, E/dE, is about 200 at 2.5 keV. The spectral coverage is 2 to 4.5 keV. The MSPEC can record four separate spectra on the framing camera at time intervals of up to several ns. The spectrometer design and initial field-test performance will be presented and compared to that of the TSPEC. Work supported by U. S. DoE/UC LLNL contract W-7405-ENG-48
Date: April 15, 2004
Creator: May, M.; Heeter, R. & Emig, J.
Object Type: Article
System: The UNT Digital Library
Aggregation of Distributed Generation Assets in New York State: Appendix (open access)

Aggregation of Distributed Generation Assets in New York State: Appendix

This report appendix describes aspects of a project to demonstrate the technical and economic feasibility of aggregating distributed generating resources in New York State. This project demonstrates a system that allows distributed generation (DG) to participate in competitive markets in much the same way as large central-station power plants. This approach involves aggregating the distributed demand-side resources into a single transaction entity consistent with the requirements of the New York Independent System Operator (NYISO). This single entity then buys or sells capacity and energy (i.e., curtailment) in NYISO markets.
Date: April 1, 2004
Creator: unknown
Object Type: Report
System: The UNT Digital Library
A New Detailed Term Accounting Opacity Code: TOPAZ (open access)

A New Detailed Term Accounting Opacity Code: TOPAZ

A new opacity code, TOPAZ, which explicitly includes configuration term structure in the bound-bound transitions is being developed. The goal is to extend the current capabilities of detailed term accounting opacity codes such as OPAL that are limited to lighter elements of astrophysical interest. At present, opacity calculations of heavier elements use statistical methods that rely on the presence of myriad spectral lines for accuracy. However, statistical approaches have been shown to be inadequate for astrophysical opacity calculations. An application of the TOPAZ code will be to study the limits of statistical methods. Comparisons of TOPAZ to other opacity codes as well as experiments are presented.
Date: April 28, 2004
Creator: Iglesias, C A; Chen, M H; Isaacs, W; Sonnad, V & Wilson, B G
Object Type: Article
System: The UNT Digital Library
Representation of the Thermodynamic Properties of Mg(NO3)2(aq) Using the Standard (Pitzer) and Extended (Archer) Ion-Interaction Models at 298.15 K (open access)

Representation of the Thermodynamic Properties of Mg(NO3)2(aq) Using the Standard (Pitzer) and Extended (Archer) Ion-Interaction Models at 298.15 K

None
Date: April 27, 2004
Creator: Rard, J A; Wijesinghe, A M & Wolery, T J
Object Type: Article
System: The UNT Digital Library
Recovery and Visualization of 3D Structure of Chromosomes from Tomographic Reconstruction Images (open access)

Recovery and Visualization of 3D Structure of Chromosomes from Tomographic Reconstruction Images

The objectives of this work include automatic recovery and visualization of a 3D chromosome structure from a sequence of 2D tomographic reconstruction images taken through the nucleus of a cell. Structure is very important for biologists as it affects chromosome functions, behavior of the cell and its state. Chromosome analysis is significant in the detection of deceases and in monitoring environmental gene mutations. The algorithm incorporates thresholding based on a histogram analysis with a polyline splitting algorithm, contour extraction via active contours, and detection of the 3D chromosome structure by establishing corresponding regions throughout the slices. Visualization using point cloud meshing generates a 3D surface. The 3D triangular mesh of the chromosomes provides surface detail and allows a user to interactively analyze chromosomes using visualization software.
Date: April 28, 2004
Creator: Babu, S; Liao, P; Shin, M C & Tsap, L V
Object Type: Article
System: The UNT Digital Library
Distribution of incoherent space - Charge tune shift of a bi-Gaussian beam (open access)

Distribution of incoherent space - Charge tune shift of a bi-Gaussian beam

The incoherent space-charge self-force tune shift of a bi-Gaussian coasting beam is revisited. The distribution density of the incoherent horizontal or vertical space-charge tune shift is computed numerically using a statistical method. Analytic approach has also been made with approximation. The results show a broad peak centered about 0.633 with a rms spread 0.168 of the linear space-charge tune shift.
Date: April 1, 2004
Creator: Ng, K. Y.
Object Type: Report
System: The UNT Digital Library
Universal Breakdown of Elasticity at the Onset of Material Failure (open access)

Universal Breakdown of Elasticity at the Onset of Material Failure

None
Date: April 20, 2004
Creator: Maloney, C & Lemaitre, A
Object Type: Article
System: The UNT Digital Library
China's Plan for Renewable Energy: Renewable Energy in China (open access)

China's Plan for Renewable Energy: Renewable Energy in China

China has rich potential for renewable energy development. Fact sheet describes Chinas policy for energy development, energy restructuring, development strategies and objectives, and measurement.
Date: April 1, 2004
Creator: unknown
Object Type: Text
System: The UNT Digital Library
Evaporative Evolution of Carbonate-Rich Brines from Synthetic Topopah Spring Tuff Pore Water, Yucca Mountain (open access)

Evaporative Evolution of Carbonate-Rich Brines from Synthetic Topopah Spring Tuff Pore Water, Yucca Mountain

The evaporation of a range of synthetic pore water solutions representative of the potential high-level-nuclear-waste repository at Yucca Mountain, NV is being investigated. The motivation of this work is to understand and predict the range of brine compositions that may contact the waste containers from evaporation of pore waters, because these brines could form corrosive thin films on the containers and impact their long-term integrity. A relatively complex synthetic Topopah Spring Tuff pore water was progressively concentrated by evaporation in a closed vessel, heated to 95 C in a series of sequential experiments. Periodic samples of the evaporating solution were taken to determine the evolving water chemistry. According to chemical divide theory at 25 C and 95 C our starting solution should evolve towards a high pH carbonate brine. Results at 95 C show that this solution evolves towards a complex brine that contains about 99 mol% Na{sup +} for the cations, and 71 mol% Cl{sup -}, 18 mol% {Sigma}CO{sub 2}(aq), 9 mol%SO{sub 4}{sup 2-} for the anions. Initial modeling of the evaporating solution indicates precipitation of aragonite, halite, silica, sulfate and fluoride phases. The experiments have been used to benchmark the use of the EQ3/6 geochemical code in predicting …
Date: April 14, 2004
Creator: Sutton, M; Alai, M & Carroll, S A
Object Type: Article
System: The UNT Digital Library
Sampling ENDL Watt Fission Spectra (open access)

Sampling ENDL Watt Fission Spectra

All of the fission spectra in the Evaluated Nuclear Data Library, ENDL [1], are defined by a simple analytical function: a Watt spectrum [2], W(a,b,E') = C*Exp[-a*E']*Sinh[(b*E'){sup 1/2}]. Where the normalization, C, is given by, C = [{pi}b/4a]{sup 1/2} Exp[b/4a]/a. The coefficients a and b vary from one isotope to another and also vary weakly with the incident neutron energy. Here E' is the secondary energy, i.e., the energy at which the fission neutrons are emitted. In ENDL energy units of MeV for incident neutron energies between 0 and 20 MeV, in all cases b is very close to 1.0, and a varies over a rather small range near 1.0. Currently there are 38 fissionable isotopes in ENDL. For each of these isotopes I have parameterized a as a simple function of the incident neutron energy, and I treat b as always equal to unity. The values of these parameters are available to TART users as part of the TART CD package [3]. This parameterization coupled with the general Watt sampling method described below results in a very fast and accurate method of sampling all of the fission spectra in ENDL. In all cases I select the fissioning isotope, define …
Date: April 1, 2004
Creator: Cullen, D E
Object Type: Report
System: The UNT Digital Library
Low Dose Radiation Hypersensitivity is Caused by p53-dependent Apoptosis (open access)

Low Dose Radiation Hypersensitivity is Caused by p53-dependent Apoptosis

Exposure to environmental radiation and the application of new clinical modalities, such as radioimmunotherapy, have heightened the need to understand cellular responses to low dose and low-dose rate ionizing radiation. Many tumor cell lines have been observed to exhibit a hypersensitivity to radiation doses below 50 cGy, which manifests as a significant deviation from the clonogenic survival response predicted by a linear-quadratic fit to higher doses. However, the underlying processes for this phenomenon remain unclear. Using a gel microdrop/flow cytometry assay to monitor single cell proliferation at early times post irradiation, we examined the response of human A549 lung carcinoma, T98G glioma and MCF7 breast carcinoma cell lines exposed to gamma radiation doses from 0 to 200 cGy delivered at 0.18 and 22 cGy/min. The A549 and T98G cells, but not MCF7 cells, showed the marked hypersensitivity at doses <50 cGy. To further characterize the low-dose hypersensitivity, we examined the influence of low-dose radiation on cell cycle status and apoptosis by assays for active caspase-3 and phosphatidylserine translocation (annexin-V binding). We observed that caspase-3 activation and annexin-V binding mirrored the proliferation curves for the cell lines. Furthermore, the low-dose hypersensitivity and annexin-V binding to irradiated A549 and T98G cells were …
Date: April 8, 2004
Creator: Enns, L; Bogen, K; Wizniak, J; Murtha, A & Weinfeld, M
Object Type: Article
System: The UNT Digital Library
Elastic and diffractive scattering at D0 (open access)

Elastic and diffractive scattering at D0

The first search for diffractively produced Z bosons in the muon decay channel is presented, using a data set collected by the D0 detector at the Fermilab Tevatron at {radical}s = 1.96 TeV between April and September 2003, corresponding to an integrated luminosity of approximately 110 pb{sup -1}. The first dN/d|t| distribution for proton-antiproton elastic scattering at this c.o.m. energy is also presented, using data collected by the D0 Forward Proton Detector between January and May 2002. The measured slope is reproduced by theoretical predictions.
Date: April 1, 2004
Creator: Edwards, Tamsin
Object Type: Article
System: The UNT Digital Library
LLNL Microsensors Program (open access)

LLNL Microsensors Program

The Microsensors Program was born out the need for enhanced sensor technology in support of the Weapons Program. In the interest of expanded diagnostic capabilities to provide true performance characteristics of weapon assemblies in flight and ground tests, a suite of sensor requirements was proposed. These potential new sensor technologies were envisioned to be completely unobtrusive and allow for the development of test vehicles (mock warheads and bomb assemblies) that were designed to mechanical and electrical specifications as close to the stockpile weapon design configuration as possible. The closeness of a test vehicle design to the respective stockpile weapon design is referred to as ''fidelity,'' with the term ''high-fidelity'' to mean all components are designed to emulate, very closely, the true system design. These efforts were in line with many activities associated with Stockpile Stewardship and were intended to enable better modeling and performance assessment without the need for underground testing. Several weapons are currently undergoing Life Extension Programs (LEP) to lengthen each weapon system's respective service life. The ability to assess the projected life of these complex assemblies is crucial to the success of the LEP activities.
Date: April 26, 2004
Creator: Lavietes, A
Object Type: Article
System: The UNT Digital Library
Building Confidence, A Story of Consensus in Kansas (open access)

Building Confidence, A Story of Consensus in Kansas

DOE's State Energy Program published this case study in conjunction with the Kansas Corporation Commission (KCC) about KCC's experience with establishing the IECC 2003 energy code in the state. The case study deals with building energy codes, home energy rating systems, and energy efficiency in residential buildings.
Date: April 1, 2004
Creator: unknown
Object Type: Text
System: The UNT Digital Library
Influence of the Environment on the General Corrosion Rate of Alloy 22 (N06022) (open access)

Influence of the Environment on the General Corrosion Rate of Alloy 22 (N06022)

Nickel (Ni) can dissolve a large amount of alloying elements while still maintaining its desirable austenitic microstructure. The resulting alloys are generally divided in families depending on the type of alloying elements they contain. Each one of these families is aimed to specific applications. Corrosive environments in industrial applications are generally divided for example in reducing acids, oxidizing acids, contaminated acids, caustic environments, oxidizing salts, etc. Depending on the application and the environment (electrolyte composition and temperature) several or single alloys may be recommended to fabricate components. The Nichromium-molybdenum (Ni-Cr-Mo) series contains a balanced selection of beneficial alloying elements so it can handle a variety of aggressive environments. By design, Alloy 22 or N06022 is one of the most versatile corrosion resistant nickel alloys since it has an outstanding corrosion resistance both in reducing and oxidizing conditions.
Date: April 19, 2004
Creator: Rebak, R B & Crook, P
Object Type: Article
System: The UNT Digital Library
Portland Public School Children Move with Propane (open access)

Portland Public School Children Move with Propane

This 2-page Clean Cities fact sheet describes the use of propane as a fuel source for Portland Public Schools' fleet of buses. It includes information on the history of the program, along with contact information for the local Clean Cities Coordinator and Portland Public Schools.
Date: April 1, 2004
Creator: unknown
Object Type: Text
System: The UNT Digital Library
WB/GEF Renewable Energy Development Project: Renewable Energy in China (open access)

WB/GEF Renewable Energy Development Project: Renewable Energy in China

Fact sheet describes China's Renewable Energy Development Project to supply electricity to rural households and institutions with wind energy and solar power (photovoltaics). World Bank and Global Environmental Facility fund the project.
Date: April 1, 2004
Creator: unknown
Object Type: Text
System: The UNT Digital Library
Proton Radiography as an electromagnetic field and density perturbation diagnostic (open access)

Proton Radiography as an electromagnetic field and density perturbation diagnostic

Laser driven proton beams have been used to diagnose transient fields and density perturbations in laser produced plasmas. Grid deflectometry techniques have been applied to proton radiography to obtain precise measurements of proton beam angles caused by electromagnetic fields in laser produced plasmas. Application of proton radiography to laser driven implosions has demonstrated that density conditions in compressed media can be diagnosed with MeV protons. This data has shown that proton radiography can provide unique insight into transient electromagnetic fields in super critical density plasmas and provide a density perturbation diagnostics in compressed matter . PACS numbers: 52.50.Jm, 52.40.Nk, 52.40.Mj, 52.70.Kz
Date: April 15, 2004
Creator: Mackinnon, A.; Patel, P.; Town, R.; Edwards, M.; Phillips, T.; Lerner, S. et al.
Object Type: Article
System: The UNT Digital Library
Laser Peening of Alloy 600 to Improve Intergranular Stress Corrosion Cracking Resistance in Power Plants (open access)

Laser Peening of Alloy 600 to Improve Intergranular Stress Corrosion Cracking Resistance in Power Plants

Laser peening is an emerging modern process that impresses a compressive stress into the surface of metals or alloys. This treatment can reduce the rate of intergranular stress corrosion cracking and fatigue cracking in structural metals or Alloy 600 needed for nuclear power plants.
Date: April 20, 2004
Creator: Chen, H; Rankin, J; Hackel, L; Frederick, G; Hickling, J & Findlan, S
Object Type: Article
System: The UNT Digital Library
Analysis of U.S. School Bus Populations and Alternative Fuel Potential (open access)

Analysis of U.S. School Bus Populations and Alternative Fuel Potential

This Clean Cities final report provides information concerning different school bus types, school bus populations, school bus miles and fuel use, school bus emissions, alternative fuel school buses, and potential for alternative fuel school bus use through 2010. It is intended to provide general information concerning the size of the school bus market in the U.S., as well as to provide some quantification of the potential for alternative fuel use in school buses in the U.S., and what that might mean for petroleum displacement and emissions reductions.
Date: April 1, 2004
Creator: Laughlin, M.
Object Type: Text
System: The UNT Digital Library
Quantifying the effects of limited CO2 fertilization on future climate (open access)

Quantifying the effects of limited CO2 fertilization on future climate

The response of the land biosphere to the ongoing increase in atmospheric CO{sub 2} is not fully understood. To evaluate the approximate upper and lower limits of land sequestration of carbon, we performed simulations using a comprehensive carbon-climate model. In one case the land biosphere is vigorously fertilized by added CO{sub 2} and sequesters carbon throughout the 21st century. In a second case, CO{sub 2} fertilization saturates in year 2000; in this case the land becomes an additional source of CO{sub 2} by 2050. The predicted atmospheric CO{sub 2} concentration at year 2100 differs by 40% between the two cases. Current uncertainties preclude determination of whether the land biosphere will amplify or damp atmospheric CO{sub 2} increases by the end of the century.
Date: April 6, 2004
Creator: Erickson, D.; Govindasamy, B.; Caldeira, K.; Mirin, A.; Thompson, S. L.; Delire, C. et al.
Object Type: Report
System: The UNT Digital Library
Large Plate Lysimeter Efficiency for Collecting Water Transported from Soil to Ground Water (open access)

Large Plate Lysimeter Efficiency for Collecting Water Transported from Soil to Ground Water

A large, zero-tension, plate lysimeter (3.05 x 2.13 m) was installed to intercept percolating soil water at Bikini Atoll (11 35'N, 165 25'E), a former nuclear test-site. In two experiments controlled amounts of irrigation water were applied over the lysimeter and leachate water was collected. Evapotranspiration (ET) calculations were made using the Penman-Monteith equation and climate data collected at the atoll. The efficiency of the lysimeter was essentially 100% in contrast to low efficiencies reported for smaller plate lysimeters. Lysimeter design, installation, and water balance results are discussed.
Date: April 14, 2004
Creator: Robison, W. L.; Stone, E. L. & Hamilton, T. F.
Object Type: Article
System: The UNT Digital Library
Hydrodynamics simulations of 2 (omega) laser propagation in underdense gasbag plasmas (open access)

Hydrodynamics simulations of 2 (omega) laser propagation in underdense gasbag plasmas

Recent 2{omega} laser propagation and stimulated Raman backscatter (SRS) experiments performed on the Helen laser have been analyzed using the radiation-hydrodynamics code hydra. These experiments utilized two diagnostics sensitive to the hydrodynamics of gasbag targets: a fast x-ray framing camera (FXI) and an SRS streak spectrometer. With a newly implemented nonlocal thermal transport model, hydra is able to reproduce many features seen in the FXI images and the SRS streak spectra. Experimental and simulated side-on FXI images suggest that propagation can be explained by classical laser absorption and the resulting hydrodynamics. Synthetic SRS spectra generated from the hydra results reproduce the details of the experimental SRS streak spectra. Most features in the synthetic spectra can be explained solely by axial density and temperature gradients. The total SRS backscatter increases with initial gasbag fill density up to {approx} 0.08 times the critical density, then decreases. Images from a near-backscatter camera (NBI) show that severe beam spray is not responsible for the trend in total backscatter. Filamentation does not appear to be a significant factor in gasbag hydrodynamics. The simulation and analysis techniques established here can be used in upcoming experimental campaigns on the Omega laser facility and the National Ignition Facility.
Date: April 5, 2004
Creator: Meezan, N. B.; Divol, L.; Marinak, M. M.; Kerbel, G. D.; Suter, L. J.; Stevenson, R. M. et al.
Object Type: Article
System: The UNT Digital Library