On the effect of x-ray irradiation on the deformation and fracture behavior of human cortical bone (open access)

On the effect of x-ray irradiation on the deformation and fracture behavior of human cortical bone

In situ mechanical testing coupled with imaging using high-energy synchrotron x-ray diffraction or tomography imaging is gaining in popularity as a technique to investigate micrometer and even sub-micrometer deformation and fracture mechanisms in mineralized tissues, such as bone and teeth. However, the role of the irradiation in affecting the nature and properties of the tissue is not always taken into account. Accordingly, we examine here the effect of x-ray synchrotron-source irradiation on the mechanistic aspects of deformation and fracture in human cortical bone. Specifically, the strength, ductility and fracture resistance (both work-of-fracture and resistance-curve fracture toughness) of human femoral bone in the transverse (breaking) orientation were evaluated following exposures to 0.05, 70, 210 and 630 kGy irradiation. Our results show that the radiation typically used in tomography imaging can have a major and deleterious impact on the strength, post-yield behavior and fracture toughness of cortical bone, with the severity of the effect progressively increasing with higher doses of radiation. Plasticity was essentially suppressed after as little as 70 kGy of radiation; the fracture toughness was decreased by a factor of five after 210 kGy of radiation. Mechanistically, the irradiation was found to alter the salient toughening mechanisms, manifest by the …
Date: January 10, 2010
Creator: Barth, Holly D.; Launey, Maximilien E.; McDowell, Alastair A.; Ager, Joel W., III & Ritchie, Robert O.
Object Type: Article
System: The UNT Digital Library
Strain Induced Magnetism in SrRuO3 Epitaxial Thin Films (open access)

Strain Induced Magnetism in SrRuO3 Epitaxial Thin Films

Epitaxial SrRuO{sub 3} thin films were grown on SrTiO{sub 3}, (LaAlO{sub 3}){sub 0.3}(SrAlO{sub 3}){sub 0.7} and LaAlO{sub 3} substrates inducing different biaxial compressive strains. Coherently strained SrRuO{sub 3} films exhibit enhanced magnetization compared to previously reported bulk and thin film values of 1.1-1.6 {micro}{sub B} per formula unit. A comparison of (001) and (110) SrRuO{sub 3} films on each substrate indicates that films on (110) oriented have consistently higher saturated moments than corresponding (001) films. These observations indicate the importance of lattice distortions in controlling the magnetic ground state in this transitional metal oxide.
Date: January 10, 2010
Creator: Grutter, A.; Wong, F.; Arenholz, E.; Liberati, M. & Suzuki, Y.
Object Type: Article
System: The UNT Digital Library
The Sulfur-Iodine Cycle: Process Analysis and Design Using Comprehensive Phase Equilibrium Measurements and Modeling (open access)

The Sulfur-Iodine Cycle: Process Analysis and Design Using Comprehensive Phase Equilibrium Measurements and Modeling

Of the 100+ thermochemical hydrogen cycles that have been proposed, the Sulfur-Iodine (S-I) Cycle is a primary target of international interest for the centralized production of hydrogen from nuclear power. However, the cycle involves complex and highly nonideal phase behavior at extreme conditions that is only beginning to be understood and modeled for process simulation. The consequence is that current designs and efficiency projections have large uncertainties, as they are based on incomplete data that must be extrapolated from property models. This situation prevents reliable assessment of the potential viability of the system and, even more, a basis for efficient process design. The goal of this NERI award (05-006) was to generate phase-equilibrium data, property models, and comprehensive process simulations so that an accurate evaluation of the S-I Cycle could be made. Our focus was on Section III of the Cycle, where the hydrogen is produced by decomposition of hydroiodic acid (HI) in the presence of water and iodine (I2) in a reactive distillation (RD) column. The results of this project were to be transferred to the nuclear hydrogen community in the form of reliable flowsheet models for the S-I process. Many of the project objectives were achieved. At Clemson …
Date: January 10, 2010
Creator: Thies, Mark C.; O'Connell, J. P. & Gorensek, Maximilian B.
Object Type: Report
System: The UNT Digital Library
317/319 Phytoremediation site monitoring report - 2009 growing season : final report. (open access)

317/319 Phytoremediation site monitoring report - 2009 growing season : final report.

In 1999, Argonne National Laboratory (Argonne) designed and installed a series of engineered plantings consisting of a vegetative cover system and approximately 800 hybrid poplars and willows rooting at various predetermined depths. The plants were installed using various methods including Applied Natural Science's TreeWell{reg_sign} system. The goal of the installation was to protect downgradient surface and groundwater by intercepting the contaminated groundwater with the tree roots, removing moisture from the upgradient soil area, reducing water infiltration, preventing soil erosion, degrading and/or transpiring the residual volatile organic compounds (VOCs), and removing tritium from the subsoil and groundwater. This report presents the results of the monitoring activities conducted by Argonne's Energy Systems (ES) Division in the growing season of 2009. Monitoring of the planted trees began soon after the trees were installed in 1999 and has been conducted every summer since then. As the trees grew and consolidated their growth into the contaminated soil and groundwater, their exposure to the contaminants was progressively shown through tissue sampling. During the 2009 sampling campaign, VOC concentrations found in the French Drain area were in general consistent with or slightly lower than the 2008 results. Additionally, closely repeated, stand wide analyses showed contaminant fluctuations that …
Date: February 10, 2010
Creator: Negri, C .N.; Benda, P. L.; Gopalakrishnan, G. & Systems, Energy
Object Type: Report
System: The UNT Digital Library
Beam Fields in an Integrated Cavity, Coupler and Window Configuration (open access)

Beam Fields in an Integrated Cavity, Coupler and Window Configuration

In a multi-bunch high current storage ring, beam generated fields couple strongly into the RF cavity coupler structure when beam arrival times are in resonance with cavity fields. In this study the integrated effect of beam fields over several thousand RF periods is simulated for the complete cavity, coupler, window and waveguide system of the PEP-II B-factory storage ring collider. We show that the beam generated fields at frequencies corresponding to several bunch spacings for this case gives rise to high field strength near the ceramic window which could limit the performance of future high current storage rings such as PEP-X or Super B-factories.
Date: February 10, 2010
Creator: Weathersby, Stephen & Novokhatski, Alexander
Object Type: Article
System: The UNT Digital Library
BPM Breakdown Potential in the PEP-II B-factory Storage Ring Collider (open access)

BPM Breakdown Potential in the PEP-II B-factory Storage Ring Collider

High current B-Factory BPM designs incorporate a button type electrode which introduces a small gap between the button and the beam chamber. For achievable currents and bunch lengths, simulations indicate that electric potentials can be induced in this gap which are comparable to the breakdown voltage. This study characterizes beam induced voltages in the existing PEP-II storage ring collider BPM as a function of bunch length and beam current.
Date: February 10, 2010
Creator: Weathersby, Stephen & Novokhatski, Alexander
Object Type: Article
System: The UNT Digital Library
Determination of rotatable and frozen CoO spins and their relationship to exchange bias in CoO/Fe/Ag(001) (open access)

Determination of rotatable and frozen CoO spins and their relationship to exchange bias in CoO/Fe/Ag(001)

The exchange bias of epitaxially grown CoO/Fe/Ag(001) was investigated using X-ray Magnetic Circular Dichroism (XMCD) and X-ray Magnetic Linear Dichroism (XMLD) techniques. A direct XMLD measurement on the CoO layer during the Fe magnetization reversal shows that the CoO compensated spins are rotatable at thinner thickness and frozen, i.e. fixed in direction to the lattice, at larger thickness. By a quantitative determination of the rotatable and frozen CoO spins as a function of the CoO film thickness, we find the remarkable result that the exchange bias is well established before frozen spins are detectable in the CoO film, contrary to the common assumption that the majority of antiferromagnetic spins need to be frozen to generate the exchange bias. We further show that the rotatable/frozen CoO spins are uniformly distributed in the CoO film.
Date: February 10, 2010
Creator: Wu, J.; Park, J.; Kim, W.; Arenholz, E.; Liberati, M.; Scholl, A. et al.
Object Type: Article
System: The UNT Digital Library
Effect of NiO spin orientation on the magnetic anisotropy of the Fe film in epitaxially grown Fe/NiO/Ag(001) and Fe/NiO/MgO(001) (open access)

Effect of NiO spin orientation on the magnetic anisotropy of the Fe film in epitaxially grown Fe/NiO/Ag(001) and Fe/NiO/MgO(001)

Single crystalline Fe/NiO bilayers were epitaxially grown on Ag(001) and on MgO(001), and investigated by Low Energy Electron Diffraction (LEED), Magneto-Optic Kerr Effect (MOKE), and X-ray Magnetic Linear Dichroism (XMLD). We find that while the Fe film has an in-plane magnetization in both Fe/NiO/Ag(001) and Fe/NiO/MgO(001) systems, the NiO spin orientation changes from in-plane direction in Fe/NiO/Ag(001) to out-of-plane direction in Fe/NiO/MgO(001). These two different NiO spin orientations generate remarkable different effects that the NiO induced magnetic anisotropy in the Fe film is much greater in Fe/NiO/Ag(001) than in Fe/NiO/MgO(001). XMLD measurement shows that the much greater magnetic anisotropy in Fe/NiO/Ag(001) is due to a 90{sup o}-coupling between the in-plane NiO spins and the in-plane Fe spins.
Date: February 10, 2010
Creator: Kim, W.; Jin, E.; Wu, J.; Park, J.; Arenholz, E.; Scholl, A. et al.
Object Type: Article
System: The UNT Digital Library
An Exact SU(2) Symmetry and Persistent Spin Helix in a Spin-Orbit Coupled System (open access)

An Exact SU(2) Symmetry and Persistent Spin Helix in a Spin-Orbit Coupled System

Spin-orbit coupled systems generally break the spin rotation symmetry. However, for a model with equal Rashba and Dresselhauss coupling constant (the ReD model), and for the [110] Dresselhauss model, a new type of SU(2) spin rotation symmetry is discovered. This symmetry is robust against spin-independent disorder and interactions, and is generated by operators whose wavevector depends on the coupling strength. It renders the spin lifetime infinite at this wavevector, giving rise to a Persistent Spin Helix (PSH). We obtain the spin fluctuation dynamics at, and away, from the symmetry point, and suggest experiments to observe the PSH.
Date: February 10, 2010
Creator: Bernevig, Andrei
Object Type: Article
System: The UNT Digital Library
Extreme Ultraviolet Laser-based Table-top Aerial Image Metrology of Lithographic Masks (open access)

Extreme Ultraviolet Laser-based Table-top Aerial Image Metrology of Lithographic Masks

We report the first at-wavelength line edge roughness measurements of patterned EUV lithography masks realized using a table-top aerial imaging system based on a table-top {lambda}=13.2 laser.
Date: February 10, 2010
Creator: Brizuela, F.; Carbajo, S.; Sakdinawat, A.; Wang, Y.; Alessi, D.; Martz, D. et al.
Object Type: Article
System: The UNT Digital Library
HOM Sensitivity in the PEP-II HER Vacuum Chamber (open access)

HOM Sensitivity in the PEP-II HER Vacuum Chamber

Synchrotron radiation is the main source of vacuum chamber heating in the PEP-II storage ring collider. This heating is reduced substantially as lattice energy is lowered. Energy scans over {Upsilon} energy states were performed by varying the high energy ring (HER) lattice energy at constant gap voltage and frequency. We observed unexpected temperature rise at particular locations when HER lattice energy was lowered from 8.6 GeV ({Upsilon}(3S)) to 8.0 GeV ({Upsilon}(2S)) while most other temperatures decreased. Bunch length measurements reveal a shorter bunch at the lower energy. The shortened bunch overheated a beam position monitoring electrode causing a vacuum breach. We explain the unexpected heating as a consequence of increased higher order mode (HOM) power generated by a shortened bunch. In this case, temperature rise helps to identify HOM sources and HOM sensitive vacuum chamber elements. Reduction of gap voltage helps to reduce this unexpected heating.
Date: February 10, 2010
Creator: Weathersby, Stephen; Novokhatski, Alexander & Sullivan, Mike
Object Type: Article
System: The UNT Digital Library
Improving Reproducibility in Sputtered Beryllium and Graded Copper Doped Beryllium Capsules (open access)

Improving Reproducibility in Sputtered Beryllium and Graded Copper Doped Beryllium Capsules

None
Date: February 10, 2010
Creator: Youngblood, K.; Hayes, J.; Moreno, K.; Nikoo, A.; Xu, H.; Alford, C. et al.
Object Type: Article
System: The UNT Digital Library
Modeling Blood Flow in a Tilted IVC Filter: Does Tilt Adversely Affect Hemodynamics? (open access)

Modeling Blood Flow in a Tilted IVC Filter: Does Tilt Adversely Affect Hemodynamics?

None
Date: February 10, 2010
Creator: Singer, M. A. & Wang, S. L.
Object Type: Article
System: The UNT Digital Library
A moving target: responding to magnetic and structural disorder in lanthanide- and actinide-based superconductors (open access)

A moving target: responding to magnetic and structural disorder in lanthanide- and actinide-based superconductors

The effects of various chemical substitutions and induced lattice disorder in the Ce- and Pu-based 115 superconductors are reviewed, with particular emphasis on results from x-ray absorption fine structure (XAFS) measurements. The PuCoGa{sub 5} system offers the opportunity to follow changes in magnetic and electronic properties due to lattice disorder as a function of time in the same samples, in addition to the more traditional approach of perturbing the superconducting state through chemical substitutions. The reviewed work establishes a baseline for such future studies by determining the intrinsic lattice order in the 115 system, successfully understanding disorder as introduced through chemical substitutions in the Ce-based 115s, and beginning to explore the surprisingly large role of self-irradiation damage directly on the PuCoGa{sub 5} lattice. These studies lay the foundation for the harder future work toward measuring chemical substitutions in PuCoGa{sub 5}, correlating effects with non-Fermi liquid behavior, and obtaining a better structural picture of the distortions induced by {alpha}-decay of the plutonium nucleus.
Date: February 10, 2010
Creator: Booth, Corwin H.; Bauer, Eric D. & Mitchel, Jeremy N.
Object Type: Article
System: The UNT Digital Library
R&D ERL: G5 test and commissioning plan (open access)

R&D ERL: G5 test and commissioning plan

Gun-to-5-cell cavity (G5) setup (Fig 1-2) can be considered as the first stage of the final BNL ERL design. The goal of the G5 setup is to test critical ERL components with the beam and characterize the beam produced by the gun. Also, this test will be used to assess effectiveness of the zigzag merger, which will be installed later in the ERL setup. The major components under the test will include the SRF gun, the five-cell SRF cavity, vacuum components, parts of the control and diagnostic systems. G5 is designed to measure the following beam parameters: (1) projected bunch emittance (?) and Twiss parameters ({alpha}, {beta}); (2) slice emittance; (3) bunch length; and (4) longitudinal and transverse halo.
Date: February 10, 2010
Creator: Kayran, D. & Pozdeyev, E.
Object Type: Report
System: The UNT Digital Library
REVISED INDEPENDENT VERIFICATION SURVEY OF A AND B RADIOACTIVE WASTE TRANSFER LINES TRENCH BROOKHAVEN NATIONAL LABORATORY (open access)

REVISED INDEPENDENT VERIFICATION SURVEY OF A AND B RADIOACTIVE WASTE TRANSFER LINES TRENCH BROOKHAVEN NATIONAL LABORATORY

REVISED INDEPENDENT VERIFICATION SURVEY OF THE A AND B RADIOACTIVE WASTE TRANSFER LINES TRENCH, BROOKHAVEN NATIONAL LABORATORY 5062-SR-01-1
Date: February 10, 2010
Creator: Weaver, P. C.
Object Type: Report
System: The UNT Digital Library
Robust Algorithm for Computing Statistical Stark Broadening of Spectral Lines (open access)

Robust Algorithm for Computing Statistical Stark Broadening of Spectral Lines

A method previously developed to solve large-scale linear systems is applied to statistical Stark broadened line shape calculations. The method is formally exact, numerically stable, and allows optimization of the integration over the quasi-static field to assure numerical accuracy. Furthermore, the method does not increase the computational effort and often can decrease it compared to the conventional approach.
Date: February 10, 2010
Creator: Iglesias, C A & Sonnad, V
Object Type: Article
System: The UNT Digital Library
Advances in Modeling Exploding Bridgewire Initiation (open access)

Advances in Modeling Exploding Bridgewire Initiation

There is great interest in applying magnetohydrodynamic (MHD) simulation techniques to the designs of electrical high explosive (HE) initiators, for the purpose of better understanding a design's sensitivities, optimizing its performance, and/or predicting its useful lifetime. Two MHD-capable LLNL codes, CALE and ALE3D, are being used to simulate the process of ohmic heating, vaporization, and plasma formation in exploding bridgewires (EBW). Initiation of the HE is simulated using Ignition & Growth reactive flow models. 1-D, 2-D and 3-D models have been constructed and studied. The models provide some intuitive explanation of the initiation process and are useful for evaluating the potential impact of identified aging mechanisms (such as the growth of intermetallic compounds or powder sintering). The end product of this work is a simulation capability for evaluating margin in proposed, modified or aged initiation system designs.
Date: March 10, 2010
Creator: Hrousis, C A & Christensen, J S
Object Type: Article
System: The UNT Digital Library
Ammonia Absorption Technologies Development for Air Conditioning, Heat Pumping and Refrigeration (open access)

Ammonia Absorption Technologies Development for Air Conditioning, Heat Pumping and Refrigeration

The project management task under the project was completed and related to the development of a plan for the implementation of the project and is thus not relevant to final report. For this reason it is not included.
Date: March 10, 2010
Creator: Rocky Research
Object Type: Report
System: The UNT Digital Library
Axions from cosmic string and wall decay (open access)

Axions from cosmic string and wall decay

If inflation occurred with a reheat temperature > T{sub PQ}, axions from the decay of global axion strings and domain walls would make an important contribution to the cosmological energy density, comparable to that from vacuum misalignment. Several groups have numerically studied the evolution of axion strings and walls in the past, however substantial uncertainties remain in their contribution to the present density {Omega}{sub a,string+wall} {approx} 1-100 (f{sub a}/10{sup 12} GeV){sup 7/6}, where f{sub a} is the axion decay constant. I will describe the numerical methods used in our simulations and show results for several string and wall configurations.
Date: March 10, 2010
Creator: Hagmann, C A
Object Type: Article
System: The UNT Digital Library
The compressibility of cubic white and orthorhombic, rhombohedral, and simple cubic black phosphorus (open access)

The compressibility of cubic white and orthorhombic, rhombohedral, and simple cubic black phosphorus

The effect of pressure on the crystal structure of white phosphorus has been studied up to 22.4 GPa. The ?alpha phase was found to transform into the alpha' phase at 0.87 +- 0.04 GPa with a volume change of 0.1 +- 0.3 cc/mol. A fit of a second order Birch- Murnaghan equation to the data gave Vo = 16.94 ? 0.08 cc/mol and Ko = 6.7 +- 0.5 GPa for the alpha phase and Vo = 16.4 +- 0.1 cc/mol and Ko = 9.1 +- 0.3 GPa for the alpha' phase. The alpha' phase was found to transform to the A17 phase of black phosphorus at 2.68 +- 0.34 GPa and then with increasing pressure to the A7 and then simple cubic phase of black phosphorus. A fit of a second order Birch-Murnaghan equation to our data combined with previous measurements gave Vo = 11.43 +- 0.05 cc/mol and Ko = 34.7 +- 0.5 GPa for the A17 phase, Vo = 9.62 +- 0.01 cc/mol and Ko = 65.0 +- 0.6 GPa for the A7 phase and , Vo = 9.23 +- 0.01 cc/mol and Ko = 72.5 +- 0.3 GPa for the simple cubic phase.
Date: March 10, 2010
Creator: Clark, Simon M & Zaug, Joseph
Object Type: Article
System: The UNT Digital Library
A direct measurement of rotatable and frozen CoO spins in exchange bias system of CoO/Fe/Ag(001) (open access)

A direct measurement of rotatable and frozen CoO spins in exchange bias system of CoO/Fe/Ag(001)

The exchange bias of epitaxially grown CoO/Fe/Ag(001) was investigated using x-ray magnetic circular dichroism and x-ray magnetic linear dichroism (XMLD) techniques. A direct XMLD measurement on the CoO layer during the Fe magnetization reversal shows that the CoO compensated spins are rotatable at thinner thickness and frozen at larger thickness. By a quantitative determination of the rotatable and frozen CoO spins as a function of the CoO film thickness, we find the remarkable result that the exchange bias is well established before frozen spins are detectable in the CoO film. We further show that the rotatable and frozen CoO spins are uniformly distributed in the CoO film.
Date: March 10, 2010
Creator: Wu, J.; Park, J. S.; Kim, W.; Arenholz, E.; Liberati, M.; Scholl, A. et al.
Object Type: Article
System: The UNT Digital Library
Efficient Bulk Data Replication for the Earth System Grid (open access)

Efficient Bulk Data Replication for the Earth System Grid

The Earth System Grid (ESG) community faces the difficult challenge of managing the distribution of massive data sets to thousands of scientists around the world. To move data replicas efficiently, the ESG has developed a data transfer management tool called the Bulk Data Mover (BDM). We describe the performance results of the current system and plans towards extending the techniques developed so far for the up- coming project, in which the ESG will employ advanced networks to move multi-TB datasets with the ulti- mate goal of helping researchers understand climate change and its potential impacts on world ecology and society.
Date: March 10, 2010
Creator: Sim, Alex; Gunter, Dan; Natarajan, Vijaya; Shoshani, Arie; Williams, Dean; Long, Jeff et al.
Object Type: Article
System: The UNT Digital Library
Measure Of Quasi-Static Toughness And Fracture Parameters For Mock Explosive And Insensitive High Explosive LX-17 (open access)

Measure Of Quasi-Static Toughness And Fracture Parameters For Mock Explosive And Insensitive High Explosive LX-17

None
Date: March 10, 2010
Creator: Ferranti, L., Jr.; Gagliardi, F. J.; Cunningham, B. J. & Vandersall, K. S.
Object Type: Article
System: The UNT Digital Library