2011 Archaea: Ecology, Metabolism, & Molecular Biology (open access)

2011 Archaea: Ecology, Metabolism, & Molecular Biology

Archaea, one of three major evolutionary lineages of life, are a fascinating and diverse group of microbes with deep roots overlapping those of eukaryotes. The focus of the 'Archaea: Ecology Metabolism & Molecular Biology' GRC conference expands on a number of emerging topics highlighting new paradigms in archaeal metabolism, genome function and systems biology; information processing; evolution and the tree of life; the ecology and diversity of archaea and their viruses. The strength of this conference lies in its ability to couple a field with a rich history in high quality research with new scientific findings in an atmosphere of stimulating exchange. This conference remains an excellent opportunity for younger scientists to interact with world experts in this field.
Date: August 5, 2011
Creator: Stedman, Keneth
System: The UNT Digital Library
2011 Quantum Control of Light & Matter Gordon Research Conference (July 31-August 5, 2011, Mount Holyoke College, South Hadley, MA) (open access)

2011 Quantum Control of Light & Matter Gordon Research Conference (July 31-August 5, 2011, Mount Holyoke College, South Hadley, MA)

Quantum control of light and matter is the quest to steer a physical process to a desirable outcome, employing constructive and destructive interference. Three basic questions address feasibility of quantum control: (1) The problem of controllability, does a control field exist for a preset initial and target state; (2) Synthesis, constructively finding the field that leads to the target; and (3) Optimal Control Theory - optimizing the field that carries out this task. These continue to be the fundamental theoretical questions to be addressed in the conference. How to realize control fields in the laboratory is an ongoing challenge. This task is very diverse viewing the emergence of control scenarios ranging from attoseconds to microseconds. How do the experimental observations reflect on the theoretical framework? The typical arena of quantum control is an open environment where much of the control is indirect. How are control scenarios realized in dissipative open systems? Can new control opportunities emerge? Can one null decoherence effects? An ideal setting for control is ultracold matter. The initial and final state can be defined more precisely. Coherent control unifies many fields of physical science. A lesson learned in one field can reflect on another. Currently quantum information …
Date: August 5, 2011
Creator: Weinacht, Thomas
System: The UNT Digital Library
23rd IAEA Fusion Energy Conference: Summary Of Sessions EX/C and ICC (open access)

23rd IAEA Fusion Energy Conference: Summary Of Sessions EX/C and ICC

An overview is given of recent experimental results in the areas of innovative confinement concepts, operational scenarios and confinement experiments as presented at the 2010 IAEA Fusion Energy Conference. Important new findings are presented from fusion devices worldwide, with a strong focus towards the scientific and technical issues associated with ITER and W7-X devices, presently under construction.
Date: January 5, 2011
Creator: Hawryluk, Richard J.
System: The UNT Digital Library
Ab initio Guided Optimization of GaTe for Radiation Detection Applications (open access)

Ab initio Guided Optimization of GaTe for Radiation Detection Applications

None
Date: April 5, 2011
Creator: Leao, C R & Lordi, V
System: The UNT Digital Library
Analysis and Modeling of Laser Ramps and Shocks in Tiitatium and Zirconium With Phase Transitions (open access)

Analysis and Modeling of Laser Ramps and Shocks in Tiitatium and Zirconium With Phase Transitions

None
Date: August 5, 2011
Creator: Heuze, O. & Swift, D. C.
System: The UNT Digital Library
Computational Needs for the Next Generation Electric Grid Proceedings (open access)

Computational Needs for the Next Generation Electric Grid Proceedings

The April 2011 DOE workshop, 'Computational Needs for the Next Generation Electric Grid', was the culmination of a year-long process to bring together some of the Nation's leading researchers and experts to identify computational challenges associated with the operation and planning of the electric power system. The attached papers provide a journey into these experts' insights, highlighting a class of mathematical and computational problems relevant for potential power systems research. While each paper defines a specific problem area, there were several recurrent themes. First, the breadth and depth of power system data has expanded tremendously over the past decade. This provides the potential for new control approaches and operator tools that can enhance system efficiencies and improve reliability. However, the large volume of data poses its own challenges, and could benefit from application of advances in computer networking and architecture, as well as data base structures. Second, the computational complexity of the underlying system problems is growing. Transmitting electricity from clean, domestic energy resources in remote regions to urban consumers, for example, requires broader, regional planning over multi-decade time horizons. Yet, it may also mean operational focus on local solutions and shorter timescales, as reactive power and system dynamics (including …
Date: October 5, 2011
Creator: Birman, Kenneth; Ganesh, Lakshmi; Renessee, Robbert van; Ferris, Michael; Hofmann, Andreas; Williams, Brian et al.
System: The UNT Digital Library
Desorption Dynamics, Internal Energies and Imaging of Organic Molecules from Surfaces with Laser Desorption and Vacuum Ultraviolet (VUV) Photoionization (open access)

Desorption Dynamics, Internal Energies and Imaging of Organic Molecules from Surfaces with Laser Desorption and Vacuum Ultraviolet (VUV) Photoionization

There is enormous interest in visualizing the chemical composition of organic material that comprises our world. A convenient method to obtain molecular information with high spatial resolution is imaging mass spectrometry. However, the internal energy deposited within molecules upon transfer to the gas phase from a surface can lead to increased fragmentation and to complications in analysis of mass spectra. Here it is shown that in laser desorption with postionization by tunable vacuum ultraviolet (VUV) radiation, the internal energy gained during laser desorption leads to minimal fragmentation of DNA bases. The internal temperature of laser-desorbed triacontane molecules approaches 670 K, whereas the internal temperature of thymine is 800 K. A synchrotron-based VUV postionization technique for determining translational temperatures reveals that biomolecules have translational temperatures in the range of 216-346 K. The observed low translational temperatures, as well as their decrease with increased desorption laser power is explained by collisional cooling. An example of imaging mass spectrometry on an organic polymer, using laser desorption VUV postionization shows 5 mu m feature details while using a 30 mu m laser spot size and 7 ns duration. Applications of laser desorption postionization to the analysis of cellulose, lignin and humic acids are briefly …
Date: April 5, 2011
Creator: Kostko, Oleg; Takahashi, Lynelle K. & Ahmed, Musahid
System: The UNT Digital Library
Dislocation Dynamics Simulations of Junctions in Hexagonal Close-Packed Crystals (open access)

Dislocation Dynamics Simulations of Junctions in Hexagonal Close-Packed Crystals

The formation and strength of dislocations in the hexagonal closed packed material beryllium are studied through dislocation junctions and the critical stress required to break them. Dislocation dynamics calculations (using the code ParaDiS) of junction maps are compared to an analytical line tension approximation in order to validate our model. Results show that the two models agree very well. Also the critical shear stress necessary to break 30{sup o} - 30{sup o} and 30{sup o} - 90{sup o} dislocation junctions is computed numerically. Yield surfaces are mapped out for these junctions to describe their stability regions as function of resolved shear stresses on the glide planes. The example of two non-coplanar binary dislocation junctions with slip planes [2-1-10] (01-10) and [-12-10] (0001) corresponding to a prismatic and basal slip respectively is chosen to verify and validate our implementation.
Date: December 5, 2011
Creator: Wu, C.; Aubry, S.; Chung, P. & Arsenlis, A.
System: The UNT Digital Library
Effects of Inclusions in HSLA Carbon Steel on Pitting Corrosion in CaCl2 (open access)

Effects of Inclusions in HSLA Carbon Steel on Pitting Corrosion in CaCl2

Susceptibility of high strength low alloy steel to localized corrosion was studied in 6.7 M CaCl{sub 2} for oil and natural gas drilling applications. Results of the immersion and electrochemical experiments showed that the steel is susceptible to pitting corrosion. Optical microscopy investigations of the polished samples revealed that 10% of the surface area was occupied by defects in the form of pits. The energy dispersive X-ray (EDX) and wavelength dispersive X-ray (WDX) chemical analyses revealed higher concentrations of Mn and S compared to the metal matrix in defected areas. These areas served as the sites for development of corrosion pits during both immersion and electrochemical experiments. The fatigue results of the corroded samples indicate that if the pit was the most significant defect, the fatigue crack initiated and propagated at this site.
Date: December 5, 2011
Creator: Ziomek-Moroz, M.; Bullard, S.; Rozman, K. & Kruzic, J.J.
System: The UNT Digital Library
ESTB: A New Beam Test Facility at SLAC (open access)

ESTB: A New Beam Test Facility at SLAC

End Station A Test Beam (ESTB) is a beam line at SLAC using a small fraction of the bunches of the 13.6 GeV electron beam from the Linac Coherent Light Source (LCLS), restoring test beam capabilities in the large End Station A (ESA) experimental hall. ESTB will provide one of a kind test beam essential for developing accelerator instrumentation and accelerator R&D, performing particle and particle astrophysics detector research, linear collider machine and detector interface (MDI) R&D studies, development of radiation-hard detectors, and material damage studies with several distinctive features. In the past, 18 institutions participated in the ESA program at SLAC. In stage I, 4 new kicker magnets will be added to divert 5 Hz of the LCLS beam to the A-line. A new beam dump will be installed and a new Personnel Protection System (PPS) is being built in ESA. In stage II, a secondary hadron target will be installed, able to produce pions up to about 12 GeV/c at 1 particle/pulse.
Date: April 5, 2011
Creator: Pivi, M.; Fieguth, T.; Hast, C.; Iverson, R.; Jaros, J.; Jobe, K. et al.
System: The UNT Digital Library
FACET Emittance Growth (open access)

FACET Emittance Growth

FACET, the Facility for Advanced Accelerator and Experimental Tests, is a new facility being constructed in sector 20 of the SLAC linac primarily to study beam driven plasma wakefield acceleration. The FACET beamline consists of a chicane and final focus system to compress the 23 GeV, 3.2 nC electron bunches to {approx}20 {micro}m long and {approx}10 {micro}m wide. Simulations of the FACET beamline indicate the short-duration and large, 1.5% rms energy spread beams may suffer a factor of four emittance growth from a combination of chromaticity, incoherent synchrotron radiation (ISR), and coherent synchrotron radiation (CSR). Emittance growth is directly correlated to head erosion in plasma wakefield acceleration and is a limiting factor in single stage performance. Studies of the geometric, CSR, and ISR components are presented. Numerical calculation of the rms emittance can be overwhelmed by long tails in the simulated phase space distributions; more useful definitions of emittance are given. A complete simulation of the beamline is presented as well, which agrees with design specifications.
Date: April 5, 2011
Creator: Frederico, J.; Hogan, M. J.; Nosochkov, Y.; Litos, M. D. & Raubenheimer, T.
System: The UNT Digital Library
Ferromagnetism in Mn-Implanted Epitaxially Grown Ge on Si(100) (open access)

Ferromagnetism in Mn-Implanted Epitaxially Grown Ge on Si(100)

We have studied ferromagnetism of Mn-implanted epitaxial Ge films on silicon. The Ge films were grown by ultrahigh vacuum chemical vapor deposition using a mixture of germane (GeH{sub 4}) and methylgermane (CH{sub 3}GeH{sub 3}) gases with a carbon concentration of less than 1 at. %, and observed surface rms roughness of 0.5 nm, as measured by atomic force microscopy. Manganese ions were implanted in epitaxial Ge films grown on Si (100) wafers to an effective concentration of 16, 12, 6, and 2 at. %. Superconducting quantum interference device measurements showed that only the three highest Mn concentration samples are ferromagnetic, while the fourth sample, with [Mn] = 2 at. %, is paramagnetic. X-ray absorption spectroscopy and x-ray magnetic circular dichroism measurements indicate that localized Mn moments are ferromagnetically coupled below the Curie temperature. Isothermal annealing of Mn-implanted Ge films with [Mn] = 16 at. % at 300 C for up to 1200 s decreases the magnetization but does not change the Curie temperature, suggesting that the amount of the magnetic phase slowly decreases with time at this anneal temperature. Furthermore, transmission electron microscopy and synchrotron grazing incidence x-ray diffraction experiments show that the Mn-implanted region is amorphous, and we believe …
Date: January 5, 2011
Creator: Guchhait, S.; Jamil, M.; Ohldag, H.; Mehta, A.; Arenholz, E.; Lian, G. et al.
System: The UNT Digital Library
Geomechanical Modeling for Thermal Spallation Drilling (open access)

Geomechanical Modeling for Thermal Spallation Drilling

None
Date: May 5, 2011
Creator: Walsh, S. D.; Lomov, I. & Roberts, J. J.
System: The UNT Digital Library
Improved resolution of hydrocarbon structures and constitutional isomers in complex mixtures using Gas Chromatography-Vacuum Ultraviolet-Mass Spectrometry (GC-VUV-MS) (Supplementary Info) (open access)

Improved resolution of hydrocarbon structures and constitutional isomers in complex mixtures using Gas Chromatography-Vacuum Ultraviolet-Mass Spectrometry (GC-VUV-MS) (Supplementary Info)

Understanding the composition of complex hydrocarbon mixtures is important for environmental studies in a variety of fields, but many prevalent compounds cannot be confidently identified using traditional gas chromatography-mass spectrometry (GC-MS) techniques. This work uses vacuum-ultraviolet (VUV) ionization to elucidate the structures of a traditionally"unresolved complex mixture" by separating components by GC retention time, tR, and mass-to-charge ratio, m/Q, which are used to determine carbon number, NC, and the number of rings and double bonds, NDBE. Constitutional isomers are resolved based on tR, enabling the most complete quantitative analysis to date of structural isomers in an environmentally-relevant hydrocarbon mixture. Unknown compounds are classified in this work by carbon number, degree of saturation, presence of rings, and degree of branching, providing structural constraints. The capabilities of this analysis are explored using diesel fuel, in which constitutional isomer distribution patterns are shown to be reproducible between carbon numbers and follow predictable rules. Nearly half of the aliphatic hydrocarbon mass is shown to be branched, suggesting branching is more important in diesel fuel than previously shown. The classification of unknown hydrocarbons and the resolution of constitutional isomers significantly improves resolution capabilities for any complex hydrocarbon mixture.
Date: September 5, 2011
Creator: Aerosol Dynamics Inc.,; Aerodyne Research, Inc.,; Tofwerk AG, Thun, Switzerland; Isaacman, Gabriel; Wilson, Kevin R.; Chan, Arthur W. H. et al.
System: The UNT Digital Library
Internal 26Al-26Mg isotope systematics of a type B CAI: Remelting of refractory precursor solids (open access)

Internal 26Al-26Mg isotope systematics of a type B CAI: Remelting of refractory precursor solids

None
Date: June 5, 2011
Creator: Kita, N. T.; Ushikubo, T.; Knight, K. B.; Mendybaev, R. A.; Davis, A. M.; Richter, F. M. et al.
System: The UNT Digital Library
International Cooperation of Seismology for Support to the CTBT (open access)

International Cooperation of Seismology for Support to the CTBT

None
Date: July 5, 2011
Creator: Gok, R.; Nakanishi, K. K.; Pasyanos, M. E.; Rodgers, A. J.; Harris, D. B.; Vergino, E. et al.
System: The UNT Digital Library
JET MIXING ANALYSIS FOR SRS HIGH-LEVEL WASTE RECOVERY (open access)

JET MIXING ANALYSIS FOR SRS HIGH-LEVEL WASTE RECOVERY

The process of recovering the waste in storage tanks at the Savannah River Site (SRS) typically requires mixing the contents of the tank to ensure uniformity of the discharge stream. Mixing is accomplished with one to four slurry pumps located within the tank liquid. The slurry pump may be fixed in position or they may rotate depending on the specific mixing requirements. The high-level waste in Tank 48 contains insoluble solids in the form of potassium tetraphenyl borate compounds (KTPB), monosodium titanate (MST), and sludge. Tank 48 is equipped with 4 slurry pumps, which are intended to suspend the insoluble solids prior to transfer of the waste to the Fluidized Bed Steam Reformer (FBSR) process. The FBSR process is being designed for a normal feed of 3.05 wt% insoluble solids. A chemical characterization study has shown the insoluble solids concentration is approximately 3.05 wt% when well-mixed. The project is requesting a Computational Fluid Dynamics (CFD) mixing study from SRNL to determine the solids behavior with 2, 3, and 4 slurry pumps in operation and an estimate of the insoluble solids concentration at the suction of the transfer pump to the FBSR process. The impact of cooling coils is not considered …
Date: July 5, 2011
Creator: Lee, S.
System: The UNT Digital Library
Kokes Awards for the 22nd North American Catalysis Society Meeting, June 5-10, 2011 (open access)

Kokes Awards for the 22nd North American Catalysis Society Meeting, June 5-10, 2011

The biennial North American Catalysis Society (NACS) Meetings are the premiere conferences in the area of catalysis, surface science, and reaction engineering. The 22nd meeting will be held the week of June 5-10, 2011 in Detroit, Michigan. The objective of the Meetings is to bring together leading researchers for intensive scientific exchange and interactions. Financial support that offsets some of the associated costs (specifically, registration fee, airline tickets, and hotel accommodations) would encourage graduate students, and for the first time undergraduate students, to attend and participate meaningfully in this conference. The funds sought in this proposal will help support the Richard J. Kokes Travel Award program. Graduate students eligible for these merit-based Awards are those who study at a North American university and who will present at the Meeting. We have currently 209 applications and we expect to be able to fund about half of them. The NACS has traditionally sought to encourage graduate student, and this year for the first time undergraduate studies, participation at the National Meetings and providing financial support is the most effective means to do so. Their attendance would contribute significantly to their scientific training and communication and presentation skills. They would be exposed to …
Date: June 5, 2011
Creator: Ribeiro, Fabio H.
System: The UNT Digital Library
LASER ENGINEERED NET SHAPING FOR REPAIR AND HYDROGEN COMPATIBILITY (open access)

LASER ENGINEERED NET SHAPING FOR REPAIR AND HYDROGEN COMPATIBILITY

A method to repair mismatched or damaged components using Laser Engineered Net Shaping{sup R} (LENS) technology to apply material was investigated for its feasibility for components exposed to hydrogen. The mechanical properties of LENS bulk materials were also tested for hydrogen compatibility. The LENS process was used to repair simulated and actual mismachined components. These sample components were hydrogen charged and burst tested in the as-received, as-damaged, and as-repaired conditions. The testing showed that there was no apparent additional deficiency associated with hydrogen charging compared to the repair technique. The repair techniques resulted in some components meeting the requirements while others did not. Additional procedure/process development is required prior to recommending production use of LENS.
Date: August 5, 2011
Creator: Korinko, P. & Adams, T.
System: The UNT Digital Library
Lattice Modeling and Calibration with Turn-by-Turn Orbit Data (open access)

Lattice Modeling and Calibration with Turn-by-Turn Orbit Data

A new method that explores turn-by-turn BPM data to calibrate lattice models of accelerators is proposed. The turn-by-turn phase space coordinates at one location of the ring are first established using data from two BPMs separated by a simple section with a known transfer matrix, such as a drift space. The phase space coordinates are then tracked with the model to predict positions at other BPMs, which can be compared to measurements. The model is adjusted to minimize the difference between the measured and predicted orbit data. BPM gains and rolls are included as fitting variables. This technique can be applied to either the entire or a section of the ring. We have tested the method experimentally on a part of the SPEAR3 ring.
Date: April 5, 2011
Creator: Huang, X.; Sebek, J. & Martin, D.
System: The UNT Digital Library
Lifetime and damage threshold properties of reflective x-ray coatings for the LCLS free-electron laser (open access)

Lifetime and damage threshold properties of reflective x-ray coatings for the LCLS free-electron laser

None
Date: May 5, 2011
Creator: Soufli, R.; Fernandez-Perea, M.; Hau-Riege, S. P.; Baker, S. L.; Robinson, J. C.; Gullikson, E. M. et al.
System: The UNT Digital Library
Measurement of Beam Lifetime and Applications for SPEAR3 (open access)

Measurement of Beam Lifetime and Applications for SPEAR3

Beam lifetime studies for the SPEAR3 storage ring are presented. The three lifetime components are separated with lifetime measurements under various combinations of beam currents and fill patterns and vertical scraper scans. Touschek lifetime is studied with rf voltage scans and with the horizontal or vertical scrapers inserted. The measurements are explained with calculations based on the calibrated lattice model. Quantum lifetime measurements are performed with reduced longitudinal and horizontal apertures, respectively, from which we deduce the radiation energy loss down to a few keV per revolution and the horizontal beam size.
Date: April 5, 2011
Creator: Huang, Xiaobiao & Corbett, Jeff
System: The UNT Digital Library
Measurement Uncertainty of High Energy Density Science Target Assemblies for the National Ignition Facility (open access)

Measurement Uncertainty of High Energy Density Science Target Assemblies for the National Ignition Facility

None
Date: August 5, 2011
Creator: Seugling, R. M.; Nederbragt, W. W.; Wilson, M. J.; Blobaum, K. J.; Peterson, S. C. & Lord, D. M.
System: The UNT Digital Library
The Muon Collider (open access)

The Muon Collider

We describe the scientific motivation for a new type of accelerator, the muon collider. This accelerator would permit an energy-frontier scientific program and yet would fit on the site of an existing laboratory. Such a device is quite challenging, and requires a substantial R&D program. After describing the ingredients of the facility, the ongoing R&D activities of the Muon Accelerator Program are discussed. A possible U.S. scenario that could lead to a muon collider at Fermilab is briefly mentioned.
Date: January 5, 2011
Creator: Zisman, Michael S.
System: The UNT Digital Library