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Catalyzed Water Oxidation by Solar Irradiation of Band-Gap-Narrowed Semiconductors (Part 2. Overview). (open access)

Catalyzed Water Oxidation by Solar Irradiation of Band-Gap-Narrowed Semiconductors (Part 2. Overview).

The objectives of this report are: (1) Investigate the catalysis of water oxidation by cobalt and manganese hydrous oxides immobilized on titania or silica nanoparticles, and dinuclear metal complexes with quinonoid ligands in order to develop a better understanding of the critical water oxidation chemistry, and rationally search for improved catalysts. (2) Optimize the light-harvesting and charge-separation abilities of stable semiconductors including both a focused effort to improve the best existing materials by investigating their structural and electronic properties using a full suite of characterization tools, and a parallel effort to discover and characterize new materials. (3) Combine these elements to examine the function of oxidation catalysts on Band-Gap-Narrowed Semiconductor (BGNSC) surfaces and elucidate the core scientific challenges to the efficient coupling of the materials functions.
Date: March 18, 2008
Creator: Fujita, E.; Khalifah, P.; Lymar, S.; Muckerman, J. T. & Rodriguez, J.
System: The UNT Digital Library
TRANSITION STATE FOR THE GAS-PHASE REACTION OF URANIUM HEXAFLUORIDE WITH WATER (open access)

TRANSITION STATE FOR THE GAS-PHASE REACTION OF URANIUM HEXAFLUORIDE WITH WATER

Density Functional Theory and small-core, relativistic pseudopotentials were used to look for symmetric and asymmetric transitions states of the gas-phase hydrolysis reaction of uranium hexafluoride, UF{sub 6}, with water. At the B3LYP/6-31G(d,p)/SDD level, an asymmetric transition state leading to the formation of a uranium hydroxyl fluoride, U(OH)F{sub 5}, and hydrogen fluoride was found with an energy barrier of +77.3 kJ/mol and an enthalpy of reaction of +63.0 kJ/mol (both including zero-point energy corrections). Addition of diffuse functions to all atoms except uranium led to only minor changes in the structure and relative energies of the reacting complex and transition state. However, a significant change in the product complex structure was found, significantly reducing the enthalpy of reaction to +31.9 kJ/mol. Similar structures and values were found for PBE0 and MP2 calculations with this larger basis set, supporting the B3LYP results. No symmetric transition state leading to the direct formation of uranium oxide tetrafluoride, UOF{sub 4}, was found, indicating that the reaction under ambient conditions likely includes several more steps than the mechanisms commonly mentioned. The transition state presented here appears to be the first published transition state for the important gas-phase reaction of UF{sub 6} with water.
Date: March 18, 2008
Creator: Garrison, S & James Becnel, J
System: The UNT Digital Library
THE USE OF VAPOR EXTRACTION SYSTEM AND ITS SUBSEQUENT REDUCTION OF WORKER EXPOSURE TO CARBON TETRACHLORIDE DURING RETRIEVAL OF HANFORDS LEGACY WASTE (open access)

THE USE OF VAPOR EXTRACTION SYSTEM AND ITS SUBSEQUENT REDUCTION OF WORKER EXPOSURE TO CARBON TETRACHLORIDE DURING RETRIEVAL OF HANFORDS LEGACY WASTE

The Hanford Site is a decommissioned nuclear productions complex located in south eastern Washington and is operated by the Department of Energy (DOE). From 1955 to 1973, carbon tetrachloride (CCl{sub 4}), used in mixtures with other organic compounds, was used to recover plutonium from aqueous streams at Z Plant located on the Hanford Site. The aqueous and organic liquid waste that remained at the end of this process was discharged to soil columns in waste cribs located near Z Plant. Included in this waste slurry along with CCl{sub 4} were tributyl phosphate, dibutyl butyl phosphate, and lard oil. (Truex et al., 2001). In the mid 1980's, CCl{sub 4} was found in the unconfined aquifer below the 200 West Area and subsequent ground water monitoring indicated that the plume was widespread and that the concentrations were increasing. It has been estimated that approximately 750,000 kg (826.7 tons) of CCl{sub 4} was discharged to the soil from 1955 to 1973. (Truex et al., 2001). With initial concentration readings of approximately 30,000 parts per million by volume (ppmv) in one well field alone, soil vapor extraction began in 1992 in an effort to remove the CCl{sub 4} from the soil. (Rohay, 1999). Since …
Date: March 18, 2008
Creator: DA, PITTS
System: The UNT Digital Library
Catalyzed Water Oxidation by Solar Irradiation of Band-Gap-Narrowed Semiconductors (Part 1. Overview). (open access)

Catalyzed Water Oxidation by Solar Irradiation of Band-Gap-Narrowed Semiconductors (Part 1. Overview).

The objectives of this report are: (1) Investigate the catalysis of water oxidation by cobalt and manganese hydrous oxides immobilized on titania or silica nanoparticles, and dinuclear metal complexes with quinonoid ligands in order to develop a better understanding of the critical water oxidation chemistry, and rationally search for improved catalysts. (2) Optimize the light-harvesting and charge-separation abilities of stable semiconductors including both a focused effort to improve the best existing materials by investigating their structural and electronic properties using a full suite of characterization tools, and a parallel effort to discover and characterize new materials. (3) Combine these elements to examine the function of oxidation catalysts on Band-Gap-Narrowed Semiconductor (BGNSC) surfaces and elucidate the core scientific challenges to the efficient coupling of the materials functions.
Date: March 18, 2008
Creator: Fujita, E.; Khalifah, P.; Lymar, S.; Muckerman, J. T. & Rodgriguez, J.
System: The UNT Digital Library
Pulse Length Control in an X-Ray FEL by Using Wakefields (open access)

Pulse Length Control in an X-Ray FEL by Using Wakefields

For the users of the high-brightness radiation sources of free-electron lasers it is desirable to reduce the FEL pulse length to 10 fs and below for time-resolved pump and probe experiments. Although it can be achieved by conventional compression methods for the electron beam or the chirped FEL pulse, the technical realization is demanding. In this presentation we study the impact of longitudinal wakefields in the undulator and how their properties can be used to reduced the amplifying part of the bunch to the desired length. Methods of actively controlling the wakefields are presented.
Date: March 18, 2008
Creator: Reiche, S.; Pellegrini, Claudio; Emma, P. & /SLAC, /UCLA
System: The UNT Digital Library
Injection Related Background due to the Transverse Feedback (open access)

Injection Related Background due to the Transverse Feedback

The background in the BaBar detector is especially high during injection, when most components are actually having reduced voltages. The situation is worse for the beam in High Energy Ring (HER) when the LER beam is present. It was found that the transverse feedback system plays an important role when stacking more charge on top of existing bunches. Lowering the feedback gain helped and it was realized later that the best scenario would be to gate off the feedback for only the one bunch, which got additional charge injected into it. The explanation is that the blown-up, but centered, original HER bunch plus the small injected off-axis bunch (each with half the charge) would stay in the ring if not touched, but the feedback system sees half the offset and wants to correct it, therefore disturbing and scraping the blown-up part.
Date: March 18, 2008
Creator: Decker, F. J.; Akre, R.; Fisher, A.; Iverson, R. & Weaver, M.
System: The UNT Digital Library
Structure and Phase Transformations in Pu Alloys (open access)

Structure and Phase Transformations in Pu Alloys

None
Date: March 18, 2008
Creator: Schwartz, A. J.; Massalski, T. B.; Cynn, H.; Evans, W. J.; Farber, D. L.; Wall, M. A. et al.
System: The UNT Digital Library
Irradiation disordering and ordering of Cu/sub 3/Au by fusion neutrons (open access)

Irradiation disordering and ordering of Cu/sub 3/Au by fusion neutrons

Ordered and partially ordered Cu/sub 3/Au alloys (S = .30 - .99) have been irradiated at 4K and 300K with fusion neutrons at RTNS-II. The disordering rate was measured by monitoring electrical resistivity. The analysis of 4K irradiations and a comparison with fission reactor irradiations indicated that the disordering rate depended upon the long-range order parameter, S, dS/d phi t = -S(k/sub 1/-k/sub 2/S), where k/sub 1/ and k/sub 2/ are scaled with damage energy. The results of 300K irradiation indicated that reordering competed significantly with disordering in the partially ordered sample. Compared to the results of 4K irradiation, the net disordering rate at 300K was higher than that at 4K. This difference and the dependence of disordering rate on S is discussed in terms of the effects of disorder and thermal displacements on cascade cooling processes.
Date: March 18, 1986
Creator: Huang, J.S.; Guinan, M.W. & Hahn, P.A.
System: The UNT Digital Library
What is wrong with the Cromer-Liberman anomalous scattering factors and what to do about them (open access)

What is wrong with the Cromer-Liberman anomalous scattering factors and what to do about them

Some sources of error in the original equation are discussed and possible corrections are suggested. (GHT)
Date: March 18, 1985
Creator: Liberman, D.A.
System: The UNT Digital Library
Review of short wavelength lasers (open access)

Review of short wavelength lasers

There has recently been a substantial amount of research devoted to the development of short wavelength amplifiers and lasers. A number of experimental results have been published wherein the observation of significant gain has been claimed on transitions in the EUV and soft x-ray regimes. The present review is intended to discuss the main approaches to the creation of population inversions and laser media in the short wavelength regime, and hopefully aid workers in the field by helping to provide access to a growing literature. The approaches to pumping EUV and soft x-ray lasers are discussed according to inversion mechanism. The approaches may be divided into roughly seven categories, including collisional excitation pumping, recombination pumping, direct photoionization and photoexcitation pumping, metastable state storage plus optical pumping, charge exchange pumping, and finally, the extension of free electron laser techniques into the EUV and soft x-ray regimes. 250 references.
Date: March 18, 1985
Creator: Hagelstein, P.L.
System: The UNT Digital Library
Fusion neutron irradiation of NiSi alloys at 4. 2K (open access)

Fusion neutron irradiation of NiSi alloys at 4. 2K

Two Ni alloys with 4 at.% Si and 12.7 at.% Si in solution have been irradiated at 4.2K with 14 MeV fusion neutrons. The resistivity damage rate of well annealed Ni-4%Si alloy showed an initial transient in the plot of d..delta..rho/d..delta..phit versus ..delta..rho. A high dislocation density appeared to reduce this transient. The resistivity damage rate of Ni-12.7%Si alloy showed an unusual behavior; d..delta..rho/d..delta..phit increases with ..delta..rho after the initial transient period. This behavior is attributed to precipitation and growth of Ni/sub 3/Si during irradiation. Post-irradiation isochronal annealing results showed significant effects of cold work and composition on recovery. Ni-4%Si recovered slower than pure nickel and a high dislocation density enhanced its recovery. For the Ni-12.7% Si alloy, recovery ended after being annealed to 38K, after which the resistivity increased with annealing temperature. This is attributed to further precipitation and growth of Ni/sub 3/Si.
Date: March 18, 1986
Creator: Guinan, M.W.; Huang, J.S. & Hahn, P.A.
System: The UNT Digital Library
Large-scale testing of structural clay tile infilled frames (open access)

Large-scale testing of structural clay tile infilled frames

A summary of large-scale cyclic static tests of structural clay tile infilled frames is given. In-plane racking tests examined the effects of varying frame stiffness, varying infill size, infill offset from frame centerline, and single and double wythe infill construction. Out-of-plane tests examined infilled frame response to inertial loadings and inter-story drift loadings. Sequential in-plane and out-of-plane loadings were performed to determine the effects of orthogonal damage and degradation on both strength and stiffness. A combined out-of-plane inertial and in-plane racking test was conducted to investigate the interaction of multi-directional loading. To determine constitutive properties of the infills, prism compression, mortar compression and various unit tile tests were performed.
Date: March 18, 1993
Creator: Flanagan, R. D. & Bennett, R. M.
System: The UNT Digital Library
Parametric variations of ion transport in TFTR (open access)

Parametric variations of ion transport in TFTR

This paper is divided into three roughly independent sections. The first is a historical review of the twenty year history of experimental ion heat transport measurements from many tokamaks. The second is a study of ion heat transport in Ohmic TFTR plasmas which shows that {chi}i {approximately} {chi}e {approx} 15{chi}i{sup neo}. Thus, ion heat transport is demonstrated to be strongly anomalous even the absence of auxiliary heating. The third section describes the variation of {chi}i with local ion temperature in TFTR during auxiliary heating, with emphasis on characterizing the differecens between transport in the L-mode and supershot regimes. The results are consistent with the conjecture that improved ion energy confinement in supershot plasmas is caused by a high ratio of T{sub 1}/T{sub e}.
Date: March 18, 1993
Creator: Scott, S. D.; Barnes, C. W. & Ernst, D.
System: The UNT Digital Library
Statement of David E. Baldwin, Associate Director for Energy, Lawrence Livermore National Laboratory and John C. Crawford, Vice President, Sandia National Laboratories, California, to the Subcommittee on Research and Development of the Committee on Environment and Public Works, United States Senate, Washington, DC, March 22, 1993 (open access)

Statement of David E. Baldwin, Associate Director for Energy, Lawrence Livermore National Laboratory and John C. Crawford, Vice President, Sandia National Laboratories, California, to the Subcommittee on Research and Development of the Committee on Environment and Public Works, United States Senate, Washington, DC, March 22, 1993

Testimony was submitted to the Senate on the environmental impacts of accelerated research and development of hydrogen-based energy systems. The advantages of hydrogen in transportation systems, in fuel cells for electric vehicles and power plants, and in energy storage from off-peak electricity production were described. The largest barrier to using hydrogen in the transportation sector is the on-board storage of enough fuel to provide an adequate driving range in an urban environment. Production methods and costs were also discussed. The authors believe a coordinated demonstration program with US industry is needed to develop the best technologies for hydrogen-fueled vehicles.
Date: March 18, 1993
Creator: Baldwin, D. E. & Crawford, J. C.
System: The UNT Digital Library
Thermally induced dephasing in periodically poled KTiOPO4 nonlinear crystals (open access)

Thermally induced dephasing in periodically poled KTiOPO4 nonlinear crystals

Experimental data that exhibits a continuous-wave, second-harmonic intensity threshold (15 kW/cm{sup 2}) that causes two-photon nonlinear absorption which leads to time-dependent photochromic damage in periodically poled KTiOPO{sub 4} is presented and verified through a thermal dephasing model.
Date: March 18, 2004
Creator: Dawson, J W; Pennington, D M; Jovanovic, I; Liao, Z M; Payne, S A; Drobshoff, A D et al.
System: The UNT Digital Library
Comment on"Air Emissions Due to Wind and Solar Power" and Supporting Information (open access)

Comment on"Air Emissions Due to Wind and Solar Power" and Supporting Information

Katzenstein and Apt investigate the important question of pollution emission reduction benefits from variable generation resources such as wind and solar. Their methodology, which couples an individual variable generator to a dedicated gas plant to produce a flat block of power is, however, inappropriate. For CO{sub 2}, the authors conclude that variable generators 'achieve {approx} 80% of the emission reductions expected if the power fluctuations caused no additional emissions.' They find even lower NO{sub x} emission reduction benefits with steam-injected gas turbines and a 2-4 times net increase in NO{sub x} emissions for systems with dry NO{sub x} control unless the ratio of energy from natural gas to variable plants is greater than 2:1. A more appropriate methodology, however, would find a significantly lower degradation of the emissions benefit than suggested by Katzenstein and Apt. As has been known for many years, models of large power system operations must take into account variable demand and the unit commitment and economic dispatch functions that are practiced every day by system operators. It is also well-known that every change in wind or solar power output does not need to be countered by an equal and opposite change in a dispatchable resource. The …
Date: March 18, 2009
Creator: Mills, Andrew D.; Wiser, Ryan H.; Milligan, Michael & O'Malley, Mark
System: The UNT Digital Library
The MINERvA Experiment (open access)

The MINERvA Experiment

The MINERvA experiment is a dedicated cross-section experiment whose aim is to measure neutrino cross sections for inclusive and exclusive final states on several nuclei. The detector is fully commissioned and began running in March 2010. As a dedicated cross-section experiment, MINERvA has a particular need to know the incident neutrino flux: both the absolute level and the energy dependence. In these proceedings we describe the MINERvA detector, give an update on the experimental status, and discuss the means to determine the neutrino flux. The MINERvA experiment is now running and has completed 25% of its full Low Energy run. There are various techniques planned for understanding the flux, including taking neutrino data at several different beam configurations. The experiment has gotten a first glimpse of two of the six configurations, and completed four horn current scans. Because of its exclusive final state reconstruction capabilities MINERvA can provide the much needed input for current and future oscillation experiments. The inclusive final state measurements and comparisons of nuclear effects across as many states as possible will provide new insights into neutrino-nucleus scattering.
Date: March 18, 2011
Creator: Harris, Deborah A. & Kopp, Sacha
System: The UNT Digital Library
Laser Inertial Fusion Energy Control Systems (open access)

Laser Inertial Fusion Energy Control Systems

A Laser Inertial Fusion Energy (LIFE) facility point design is being developed at LLNL to support an Inertial Confinement Fusion (ICF) based energy concept. This will build upon the technical foundation of the National Ignition Facility (NIF), the world's largest and most energetic laser system. NIF is designed to compress fusion targets to conditions required for thermonuclear burn. The LIFE control systems will have an architecture partitioned by sub-systems and distributed among over 1000's of front-end processors, embedded controllers and supervisory servers. LIFE's automated control subsystems will require interoperation between different languages and target architectures. Much of the control system will be embedded into the subsystem with well defined interface and performance requirements to the supervisory control layer. An automation framework will be used to orchestrate and automate start-up and shut-down as well as steady state operation. The LIFE control system will be a high parallel segmented architecture. For example, the laser system consists of 384 identical laser beamlines in a 'box'. The control system will mirror this architectural replication for each beamline with straightforward high-level interface for control and status monitoring. Key technical challenges will be discussed such as the injected target tracking and laser pointing feedback. This talk …
Date: March 18, 2011
Creator: Marshall, C.; Carey, R.; Demaret, R.; Edwards, O.; Lagin, L. & Van Arsdall, P.
System: The UNT Digital Library
In vitro High-Resolution Architecture and Structural Dynamics of Bacterial Systems (open access)

In vitro High-Resolution Architecture and Structural Dynamics of Bacterial Systems

None
Date: March 18, 2010
Creator: Malkin, A. J.; Plomp, M.; Leighton, T. J.; Vogelstein, B. & Holman, H.
System: The UNT Digital Library
The SEMATECH Berkeley MET: extending EUV learning to 16-nm half pitch (open access)

The SEMATECH Berkeley MET: extending EUV learning to 16-nm half pitch

Several high-performing resists identified in the past two years have been exposed at the 0.3-numerical-aperture (NA) SEMATECH Berkeley Microfield Exposure Tool (BMET) with an engineered dipole illumination optimized for 18-nm half pitch. Five chemically amplified platforms were found to support 20-nm dense patterning at a film thickness of approximately 45 nm. At 19-nm half pitch, however, scattered bridging kept all of these resists from cleanly resolving larger areas of dense features. At 18-nm half pitch, none of the resists were are able to cleanly resolve a single line within a bulk pattern. With this same illumination a directly imageable metal oxide hardmask showed excellent performance from 22-nm half pitch to 17-nm half pitch, and good performance at 16-nm half pitch, closely following the predicted aerial image contrast. This indicates that observed limitations of the chemically amplified resists are indeed coming from the resist and not from a shortcoming of the exposure tool. The imageable hardmask was also exposed using a Pseudo Phase-Shift-Mask technique and achieved clean printing of 15-nm half pitch lines and modulation all the way down to the theoretical 12.5-nm resolution limit of the 0.3-NA SEMATECH BMET.
Date: March 18, 2011
Creator: Anderson, Christopher N.; Baclea-an, Lorie Mae; Denham, Paul E.; George, Simi; Goldberg, Kenneth A.; Jones, Michael et al.
System: The UNT Digital Library
A Green Prison: Santa Rita Jail Creeps Toward Zero Net Energy (ZNE) (open access)

A Green Prison: Santa Rita Jail Creeps Toward Zero Net Energy (ZNE)

In an effort to create broad access to its optimization software, Lawrence Berkeley National Laboratory (LBNL), in collaboration with the University of California at Davis (UC Davis) and OSISoft, has recently developed a Software as a Service (SaaS) Model for reducing energy costs, cutting peak power demand, and reducing carbon emissions for multipurpose buildings. UC Davis currently collects and stores energy usage data from buildings on its campus. Researchers at LBNL sought to demonstrate that a SaaS application architecture could be built on top of this data system to optimize the scheduling of electricity and heat delivery in the building. The SaaS interface, known as WebOpt, consists of two major parts: a) the investment& planning and b) the operations module, which builds on the investment& planning module. The operational scheduling and load shifting optimization models within the operations module use data from load prediction and electrical grid emissions models to create an optimal operating schedule for the next week, reducing peak electricity consumption while maintaining quality of energy services. LBNL's application also provides facility managers with suggested energy infrastructure investments for achieving their energy cost and emission goals based on historical data collected with OSISoft's system. This paper describes these …
Date: March 18, 2011
Creator: Marnay, Chris; DeForest, Nicholas; Stadler, Michael; Donadee, John; Dierckxsens, Carlos; Mendes, Gonçalo et al.
System: The UNT Digital Library
Systematics of Coupling Flows in AdS Backgrounds (open access)

Systematics of Coupling Flows in AdS Backgrounds

We give an effective field theory derivation, based on the running of Planck brane gauge correlators, of the large logarithms that arise in the predictions for low energy gauge couplings in compactified AdS}_5 backgrounds, including the one-loop effects of bulk scalars, fermions, and gauge bosons. In contrast to the case of charged scalars coupled to Abelian gauge fields that has been considered previously in the literature, the one-loop corrections are not dominated by a single 4D Kaluza-Klein mode. Nevertheless, in the case of gauge field loops, the amplitudes can be reorganized into a leading logarithmic contribution that is identical to the running in 4D non-Abelian gauge theory, and a term which is not logarithmically enhanced and is analogous to a two-loop effect in 4D. In a warped GUT model broken by the Higgs mechanism in the bulk,we show that the matching scale that appears in the large logarithms induced by the non-Abelian gauge fields is m_{XY}^2/k where m_{XY} is the bulk mass of the XY bosons and k is the AdS curvature. This is in contrast to the UV scale in the logarithmic contributions of scalars, which is simply the bulk mass m. Our results are summarized in a set …
Date: March 18, 2003
Creator: Goldberger, Walter D. & Rothstein, Ira Z.
System: The UNT Digital Library
MASS MEASUREMENT UNCERTAINTY FOR PLUTONIUM ALIQUOTS ASSAYED BY CONTROLLED-POTENTIAL COULOMETRY (open access)

MASS MEASUREMENT UNCERTAINTY FOR PLUTONIUM ALIQUOTS ASSAYED BY CONTROLLED-POTENTIAL COULOMETRY

Minimizing plutonium measurement uncertainty is essential to nuclear material control and international safeguards. In 2005, the International Organization for Standardization (ISO) published ISO 12183 'Controlled-potential coulometric assay of plutonium', 2nd edition. ISO 12183:2005 recommends a target of {+-}0.01% for the mass of original sample in the aliquot because it is a critical assay variable. Mass measurements in radiological containment were evaluated and uncertainties estimated. The uncertainty estimate for the mass measurement also includes uncertainty in correcting for buoyancy effects from air acting as a fluid and from decreased pressure of heated air from the specific heat of the plutonium isotopes.
Date: March 18, 2009
Creator: Holland, M. & Cordaro, J.
System: The UNT Digital Library
Extended Simulations of Graphene Growth with Updated Rate Coefficients (open access)

Extended Simulations of Graphene Growth with Updated Rate Coefficients

New simulations of graphene growth in flame environments are presented. The simulations employ a kinetic Monte Carlo (KMC) algorithm coupled to molecular mechanics (MM) geometry optimization to track individual graphenic species as they evolve. Focus is given to incorporation of five-member rings and resulting curvature and edge defects. The model code has been re-written to be more computationally efficient enabling a larger set of simulations to be run, decreasing stochastic fluctuations in the averaged results. The model also includes updated rate coefficients for graphene edge reactions recently published in the literature. The new simulations are compared to results from the previous model as well as to hydrogen to carbon ratios recorded in experiment and calculated with alternate models.
Date: March 18, 2010
Creator: Whitesides, R.; You, X. & Frenklach, M.
System: The UNT Digital Library