2010 Non-Proliferation Treaty (NPT) Review Conference: Key Issues and Implications (open access)

2010 Non-Proliferation Treaty (NPT) Review Conference: Key Issues and Implications

The report includes a short summary of the provisions and goals of the Non-Proliferation Treaty (NPT) and a brief history of past review conferences. It also discusses the key issues that the participants are likely to address during the 2010 conference.
Date: May 3, 2010
Creator: Kerr, Paul K.; Nikitin, Mary Beth; Woolf, Amy F. & Medalia, Jonathan
Object Type: Report
System: The UNT Digital Library
Analysis of the Spectral Function of Nd1.85Ce0.15CuO4, Obtained by Angle Resolved Photoemission Spectroscopy (open access)

Analysis of the Spectral Function of Nd1.85Ce0.15CuO4, Obtained by Angle Resolved Photoemission Spectroscopy

Samples of Nd{sub 2-x}Ce{sub x}CuO{sub 4}, an electron-doped high temperature superconducting cuprate (HTSC), near optimal doping at x = 0.155 were measured via angle resolved photoemission (ARPES). We report a renormalization feature in the self energy ('kink') in the band dispersion at {approx} 50-60 meV present in nodal and antinodal cuts across the Fermi surface. Specifically, while the kink had been seen in the antinodal region, it is now observed also in the nodal region, reminiscent of what has been observed in hole-doped cuprates.
Date: May 3, 2010
Creator: Schmitt, F.
Object Type: Article
System: The UNT Digital Library
Angle-resolved photoemission studies of lattice polaron formation in the cuprate Ca2CuO2Cl2 (open access)

Angle-resolved photoemission studies of lattice polaron formation in the cuprate Ca2CuO2Cl2

To elucidate the nature of the single-particle excitations in the undoped parent cuprates, we have performed a detailed study of Ca{sub 2}CuO{sub 2}Cl{sub 2} using photoemission spectroscopy. The photoemission lineshapes of the lower Hubbard band are found to be well-described by a polaron model. By comparing the lineshape and temperature dependence of the lower Hubbard band with additional O 2p and Ca 3p states, we conclude that the dominant broadening mechanism arises from the interaction between the photohole and the lattice. The strength of this interaction was observed to be strongly anisotropic and may have important implications for the momentum dependence of the first doped hole states.
Date: May 3, 2010
Creator: Shen, K.M.
Object Type: Article
System: The UNT Digital Library
Anomalous Fermi-Surface Dependent Pairing in a Self-Doped High-Tc Superconductor (open access)

Anomalous Fermi-Surface Dependent Pairing in a Self-Doped High-Tc Superconductor

We report the discovery of a self-doped multi-layer high T{sub c} superconductor Ba{sub 2}Ca{sub 3}Cu{sub 4}O{sub 8}F{sub 2} (F0234) which contains distinctly different superconducting gap magnitudes along its two Fermi surface(FS) sheets. While formal valence counting would imply this material to be an undoped insulator, it is a self-doped superconductor with a T{sub c} of 60K, possessing simultaneously both electron- and hole-doped FS sheets. Intriguingly, the FS sheet characterized by the much larger gap is the electron-doped one, which has a shape disfavoring two electronic features considered to be important for the pairing mechanism: the van Hove singularity and the antiferromagnetic ({pi}/a, {pi}/a) scattering.
Date: May 3, 2010
Creator: Chen, Y.
Object Type: Article
System: The UNT Digital Library
A Direct, Biomass-Based Synthesis of Benzoic Acid: Formic Acid-Mediated Deoxygenation of the Glucose-Derived Materials Quinic Acid and Shikimic Acid (open access)

A Direct, Biomass-Based Synthesis of Benzoic Acid: Formic Acid-Mediated Deoxygenation of the Glucose-Derived Materials Quinic Acid and Shikimic Acid

An alternative biomass-based route to benzoic acid from the renewable starting materials quinic acid and shikimic acid is described. Benzoic acid is obtained selectively using a highly efficient, one-step formic acid-mediated deoxygenation method.
Date: May 3, 2010
Creator: Arceo, Elena; Ellman, Jonathan & Bergman, Robert
Object Type: Article
System: The UNT Digital Library
Direct observation of the mass renormalization in SrVO3 by angle resolved photoemission spectroscopy (open access)

Direct observation of the mass renormalization in SrVO3 by angle resolved photoemission spectroscopy

We have performed an angle-resolved photoemission study of the three-dimensional perovskite-type SrVO{sub 3}. Observed spectral weight distribution of the coherent part in the momentum space shows cylindrical Fermi surfaces consisting of the V 3d t{sub 2g} orbitals as predicted by local-density approximation (LDA) band-structure calculation. The observed energy dispersion shows a moderately enhanced effective mass compared to the LDA results, corresponding to the effective mass enhancement seen in the thermodynamic properties. Contributions from the bulk and surface electronic structures to the observed spectra are discussed based on model calculations.
Date: May 3, 2010
Creator: Yoshida, t.
Object Type: Article
System: The UNT Digital Library
Doping Dependent Charge Transfer Gap and Realistic Electronic Model of n-type Cuprate Superconductors (open access)

Doping Dependent Charge Transfer Gap and Realistic Electronic Model of n-type Cuprate Superconductors

Based on the analysis of the measurement data of angle-resolved photoemission spectroscopy (ARPES) and optics, we show that the charge transfer gap is significantly smaller than the optical one and is reduced by doping in electron doped cuprate superconductors. This leads to a strong charge fluctuation between the Zhang-Rice singlet and the upper Hubbard bands. The basic model for describing this system is a hybridized two-band t-J model. In the symmetric limit where the corresponding intra- and inter-band hopping integrals are equal to each other, this two-band model is equivalent to the Hubbard model with an antiferromagnetic exchange interaction (i.e. the t-U-J model). The mean-field result of the t-U-J model gives a good account for the doping evolution of the Fermi surface and the staggered magnetization.
Date: May 3, 2010
Creator: Xiang, T.
Object Type: Article
System: The UNT Digital Library
Doping Evolution of the Underlying Fermi Surface in La_2&#8722xSr_xCuO_4 (open access)

Doping Evolution of the Underlying Fermi Surface in La_2&#8722xSr_xCuO_4

We have performed a systematic doping dependent study of La{sub 2-x}Sr{sub x}CuO{sub 4} (LSCO) (0.03 {le} x {le} 0.3) by angle-resolved photoemission spectroscopy. In the entire doping range, the underlying 'Fermi surface' determined from the low energy spectral weight approximately satisfies Luttinger's theorem, even down to the lightly-doped region. This is in strong contrast to the result on Ca{sub 2-x}Na{sub x}CuO{sub 2}Cl{sub 2} (Na-CCOC), which shows a strong deviation from Luttinger's theorem. The differences between LSCO and Na-CCOC are correlated with the different behaviors of the chemical potential shift and spectral weight transfer induced by hole doping.
Date: May 3, 2010
Creator: Yoshida, T.
Object Type: Article
System: The UNT Digital Library
Enhanced superconducting pairing interaction in indium-doped tin telluride (open access)

Enhanced superconducting pairing interaction in indium-doped tin telluride

The ferroelectric degenerate semiconductor Sn{sub 1-{delta}}Te exhibits superconductivity with critical temperatures, T{sub c}, of up to 0.3 K for hole densities of order 10{sup 21} cm{sup -3}. When doped on the tin site with greater than x{sub c} = 1.7(3)% indium atoms, however, superconductivity is observed up to 2 K, though the carrier density does not change significantly. We present specific heat data showing that a stronger pairing interaction is present for x > x{sub c} than for x < x{sub c}. By examining the effect of In dopant atoms on both T{sub c} and the temperature of the ferroelectric structural phase transition, T{sub SPT}, we show that phonon modes related to this transition are not responsible for this T{sub c} enhancement, and discuss a plausible candidate based on the unique properties of the indium impurities.
Date: May 3, 2010
Creator: Erickson, A.S.
Object Type: Article
System: The UNT Digital Library
Federal Register, Volume 75, Number 84, May 3, 2010, Pages 23151-23556 (open access)

Federal Register, Volume 75, Number 84, May 3, 2010, Pages 23151-23556

Daily publication of the U.S. Office of the Federal Register contains rules and regulations, proposed legislation and rule changes, and other notices, including "Presidential proclamations and Executive Orders, Federal agency documents having general applicability and legal effect, documents required to be published by act of Congress, and other Federal agency documents of public interest" (p. ii). Table of Contents starts on page iii.
Date: May 3, 2010
Creator: United States. Office of the Federal Register.
Object Type: Journal/Magazine/Newsletter
System: The UNT Digital Library
Fermi Surface Evolution Across Multiple Charge Density Wave Transitions in ErTe3 (open access)

Fermi Surface Evolution Across Multiple Charge Density Wave Transitions in ErTe3

None
Date: May 3, 2010
Creator: Moore, R. G.
Object Type: Article
System: The UNT Digital Library
Glass Composition Constraint Recommendations for Use in Life-Cycle Mission Modeling (open access)

Glass Composition Constraint Recommendations for Use in Life-Cycle Mission Modeling

The component concentration limits that most influence the predicted Hanford life-cycle HLW glass volume by HTWOS were re-evaluated. It was assumed that additional research and development work in glass formulation and melter testing would be performed to improve the understanding of component effects on the processability and product quality of these HLW glasses. Recommendations were made to better estimate the potential component concentration limits that could be applied today while technology development is underway to best estimate the volume of HLW glass that will eventually be produced at Hanford. The limits for concentrations of P2O5, Bi2O3, and SO3 were evaluated along with the constraint used to avoid nepheline formation in glass. Recommended concentration limits were made based on the current HLW glass property models being used by HTWOS (Vienna et al. 2009). These revised limits are: 1) The current ND should be augmented by the OB limit of OB ≤ 0.575 so that either the normalized silica (NSi) is less that the 62% limit or the OB is below the 0.575 limit. 2) The mass fraction of P2O5 limit should be revised to allow for up to 4.5 wt%, depending on CaO concentrations. 3) A Bi2O3 concentration limit of 7 …
Date: May 3, 2010
Creator: McCloy, John S. & Vienna, John D.
Object Type: Report
System: The UNT Digital Library
HANFORD TANK CLEANUP UPDATE APRIL 2010 (open access)

HANFORD TANK CLEANUP UPDATE APRIL 2010

None
Date: May 3, 2010
Creator: Berriochoa, M. V.
Object Type: Report
System: The UNT Digital Library
The hierarchy of multiple many-body interaction scales in high-temperature superconductors (open access)

The hierarchy of multiple many-body interaction scales in high-temperature superconductors

To date, angle-resolved photoemission spectroscopy has been successful in identifying energy scales of the many-body interactions in correlated materials, focused on binding energies of up to a few hundred meV below the Fermi energy. Here, at higher energy scale, we present improved experimental data from four families of high-T{sub c} superconductors over a wide doping range that reveal a hierarchy of many-body interaction scales focused on: the low energy anomaly ('kink') of 0.03-0.09eV, a high energy anomaly of 0.3-0.5eV, and an anomalous enhancement of the width of the LDA-based CuO{sub 2} band extending to energies of {approx} 2 eV. Besides their universal behavior over the families, we find that all of these three dispersion anomalies also show clear doping dependence over the doping range presented.
Date: May 3, 2010
Creator: Meevasana, W.
Object Type: Article
System: The UNT Digital Library
Iran: U.S. Concerns and Policy Responses (open access)

Iran: U.S. Concerns and Policy Responses

This report discusses the reasons that Iran is considered a threat to U.S. security, including Iran's nuclear program, involvement with terrorist organizations, and involvement with neighboring countries' local governments. The report also discusses ways which the U.S. hopes to modify Iran's behavior with sanctions, and the effectiveness of these sanctions.
Date: May 3, 2010
Creator: Katzman, Kenneth
Object Type: Report
System: The UNT Digital Library
Key Provisions that Take Effect Immediately (open access)

Key Provisions that Take Effect Immediately

A paper about affordable health care in the united states. It pertains to changes taking place for small businesses, seniors, the privately insured, and the uninsured.
Date: May 3, 2010
Creator: Pelosi, Nancy
Object Type: Report
System: The UNT Digital Library
Muon g-2 Calorimeter Prototypes (open access)

Muon g-2 Calorimeter Prototypes

The proposed design is a tungsten-scintillating fiber calorimeter with 35 segments, each read out by a separate PMT. Tungsten, which is significantly denser than lead, produces compact showers. This is necessary, in order to improve shower separation in analysis and to fully contain the showers within a calorimeter that satisfies the strict space constraints of the experiment. A single calorimeter segment (4 x 6 x 15 cm{sup 3}) has been constructed in order establish the feasibility of the new design and study its properties. Initial tests of the detector segment at the Paul Scherrer Institute were conducted with a low energy < 400 MeV/c electron beam. A higher-energy test with electrons up to a few GeV/c was performed at the Test Beam Facility under the experimental number T-967. All data from that test have been analyzed and published, and the tungsten-scintillating fiber calorimeter still appears to be a viable candidate. For this test beam run, a larger calorimeter (15 x 15 x 11 cm{sup 3}) has been constructed and an emphasis will be placed on understanding shower leakage and the ability to separate pileup events with a more granular readout. The experimenters will measure the energy resolution, linearity, and shower …
Date: May 3, 2010
Creator: Polly, Chris
Object Type: Report
System: The UNT Digital Library
Navy Force Structure and Shipbuilding Plans: Background and Issues for Congress (open access)

Navy Force Structure and Shipbuilding Plans: Background and Issues for Congress

This report provides background information and presents potential issues for Congress concerning the Navy's ship force-structure goals and shipbuilding plans. The planned size of the Navy, the rate of Navy ship procurement, and the prospective affordability of the Navy's shipbuilding plans have been matters of concern for the congressional defense committees for the past several years. Decisions that Congress makes on Navy shipbuilding programs can substantially affect Navy capabilities and funding requirements, and the U.S. shipbuilding industrial base.
Date: May 3, 2010
Creator: O'Rourke, Ronald
Object Type: Report
System: The UNT Digital Library
The New START Treaty: Central Limits and Key Provisions (open access)

The New START Treaty: Central Limits and Key Provisions

This report provides an overview of the New Strategic Arms Reductions Treaty (START), including a comparison to the original START Treaty, the belief of the Obama Administration and outside analysts that New START will enhance U.S. national security, and the criticisms of those who say that New START is a distraction from more important items on the nonproliferation agenda.
Date: May 3, 2010
Creator: Woolf, Amy F.
Object Type: Report
System: The UNT Digital Library
Nitrous Oxide from Agricultural Sources: Potential Role in Greenhouse Gas Emission Reduction and Ozone Recovery (open access)

Nitrous Oxide from Agricultural Sources: Potential Role in Greenhouse Gas Emission Reduction and Ozone Recovery

None
Date: May 3, 2010
Creator: unknown
Object Type: Report
System: The UNT Digital Library
An Overview of USDA Rural Development Programs (open access)

An Overview of USDA Rural Development Programs

None
Date: May 3, 2010
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Potential Impact of Adopting Maximum Technologies as Minimum Efficiency Performance Standards in the U.S. Residential Sector (open access)

Potential Impact of Adopting Maximum Technologies as Minimum Efficiency Performance Standards in the U.S. Residential Sector

The US Department of Energy (US DOE) has placed lighting and appliance standards at a very high priority of the U.S. energy policy. However, the maximum energy savings and CO2 emissions reduction achievable via minimum efficiency performance standards (MEPS) has not yet been fully characterized. The Bottom Up Energy Analysis System (BUENAS), first developed in 2007, is a global, generic, and modular tool designed to provide policy makers with estimates of potential impacts resulting from MEPS for a variety of products, at the international and/or regional level. Using the BUENAS framework, we estimated potential national energy savings and CO2 emissions mitigation in the US residential sector that would result from the most aggressive policy foreseeable: standards effective in 2014 set at the current maximum technology (Max Tech) available on the market. This represents the most likely characterization of what can be maximally achieved through MEPS in the US. The authors rely on the latest Technical Support Documents and Analytical Tools published by the U.S. Department of Energy as a source to determine appliance stock turnover and projected efficiency scenarios of what would occur in the absence of policy. In our analysis, national impacts are determined for the following end uses: …
Date: May 3, 2010
Creator: Letschert, Virginie; Desroches, Louis-Benoit; McNeil, Michael & Saheb, Yamina
Object Type: Article
System: The UNT Digital Library
Pressure-induced quenching of the charge-density-wave state observed by x-ray diffraction (open access)

Pressure-induced quenching of the charge-density-wave state observed by x-ray diffraction

We report an x-ray diffraction study on the charge-density-wave (CDW) LaTe{sub 3} and CeTe{sub 3} compounds as a function of pressure. We extract the lattice constants and the CDW modulation wave-vector, and provide direct evidence for a pressure-induced quenching of the CDW phase. We observe subtle differences between the chemical and mechanical compression of the lattice. We account for these with a scenario where the effective dimensionality in these CDW systems is dependent on the type of lattice compression and has a direct impact on the degree of Fermi surface nesting and on the strength of fluctuation effects.
Date: May 3, 2010
Creator: Sacchetti, A.
Object Type: Article
System: The UNT Digital Library

Renewable Resources for Hydrogen

This presentation provides an overview of renewable resources for hydrogen. It was presented at the National Hydrogen Association Hydrogen Conference & Expo in Long Beach, CA, May 3-6, 2010.
Date: May 3, 2010
Creator: Jalalzadeh-Azar, A. A.
Object Type: Presentation
System: The UNT Digital Library