Amorphous and nanocrystalline Mg{sub 2}Si thin film electrodes (open access)

Amorphous and nanocrystalline Mg{sub 2}Si thin film electrodes

Mg{sub 2}Si films, prepared by pulsed laser deposition (PLD), were amorphous, as prepared, and nanocrystalline following annealing. Their micro-structure and electrochemical characteristics were studied by high resolution transmission electron microscopy (HRTEM) and electrochemical cycling against lithium. HRTEM analysis revealed that some excess Si was present in the films. The more amorphous thinner film exhibited excellent cyclability. However, when the film becomes crystalline, the irreversible capacity loss was more significant during the initial cycling and after *50 cycles. Interpretations of the superior stability of the amorphous films are examined.
Date: February 4, 2003
Creator: Song, Seung-Wan; Striebel, Kathryn A.; Song, Xiangyun & Cairns, Elton J.
System: The UNT Digital Library
The highly successful safe remediation of the Fernald waste pits undertaken under the privatization model (open access)

The highly successful safe remediation of the Fernald waste pits undertaken under the privatization model

Remediation of eight waste pits at the Department of Energy (DOE) Fernald site, located northwest of Cincinnati, Ohio, involves excavating approximately one million tonnes in-situ of low-level waste which were placed in pits during Fernald's production era. This unique project, one of the largest in the history of CERCLA/Superfund, includes uranium and thorium contaminated waste, soils and sludges. These wet soils and sludges are thermally dried in a processing facility to meet Department of Transportation (DOT) transportation and disposal facility waste acceptance criteria, loaded into railcars and shipped to the Envirocare waste disposal facility at Clive, Utah. This project is now approximately 60% complete with more than 415,000 tonnes (460,000 tons) of waste material safely shipped in 74 unit trains to Envirocare. Work is scheduled to be completed in early 2005. Success to date demonstrates that a major DOE site remediation project can be safely and successfully executed in partnership with private industry, utilizing proven commercial best practices, existing site labor resources and support of local stakeholders. In 1997 under the DOE's privatization initiative, Fluor Fernald, Inc. (Fluor Fernald) solicited the services of the remediation industry to design, engineer, procure, construct, own and operate a facility that would undertake the …
Date: February 23, 2003
Creator: Cherry, Mark; Lojek, Dave & Murphy, Con
System: The UNT Digital Library
Mechanical Behavior and Fractography of 304 Stainless Steel with High Hydrogen Concentration (open access)

Mechanical Behavior and Fractography of 304 Stainless Steel with High Hydrogen Concentration

Hydrogen embrittlement of 304 stainless steel with different hydrogen concentrations has been investigated. An electrochemical technique was used to effectively charge the high level of hydrogen into 304 stainless steel in a short period of time. At 25 ppm of hydrogen, 304 stainless steel loses 10 percent of its original mechanical strength and 20 percent plasticity. Although the ductile feature dominates the fractography, the brittle crown area near the outer surface shows the intergranular rupture effected by hydrogen. At 60 ppm of hydrogen, 304 stainless steel loses 23 percent of its strength and 38 percent plasticity, where the brittle mode dominates the fracture of the materials. Experimental results show that hydrogen damage to the performance of 304 stainless steel is significant even at very low levels. The fractograph analysis indicates the high penetration ability of hydrogen in 304 stainless steel. This work also demonstrates the advantages of the electrochemical charging technique in the study of hydrogen embrittlement.
Date: February 5, 2003
Creator: Au, M.
System: The UNT Digital Library
PACKAGING AND DISPOSAL OF A RADIUM BERYLLIUM SOURCE USING DEPLETED URANIUM POLYETHYLENE COMPOSITE SHIELDING. (open access)

PACKAGING AND DISPOSAL OF A RADIUM BERYLLIUM SOURCE USING DEPLETED URANIUM POLYETHYLENE COMPOSITE SHIELDING.

Two, 111 GBq (3 Curie) radium-beryllium (RaBe) sources were in underground storage at the Brookhaven National Laboratory (BNL) since 1988. These sources originated from Princeton Plasma Physics Laboratory (PPPL) where they were used to calibrate neutron detection diagnostics. In 1999, PPPL and BNL began a collaborative effort to expand the use of an innovative pilot-scale technology and bring it to full-scale deployment to shield these sources for eventual transport and burial at the Hanford Burial site. The transport/disposal container was constructed of depleted uranium oxide encapsulated in polyethylene to provide suitable shielding for both gamma and neutron radiation. This new material can be produced from recycled waste products (DU and polyethylene), is inexpensive, and can be disposed with the waste, unlike conventional lead containers, thus reducing exposure time for workers. This paper will provide calculations and information that led to the initial design of the shielding. We will also describe the production-scale processing of the container, cost, schedule, logistics, and many unforeseen challenges that eventually resulted in the successful fabrication and deployment of this shield. We will conclude with a description of the final configuration of the shielding container and shipping package along with recommendations for future shielding designs.
Date: February 23, 2003
Creator: Rule, K.; Kalb, P. & Kwaschyn, P.
System: The UNT Digital Library
Alpha-Gallium (010) surface reconstruction: a LEED structural analysis of the (1x1) room temperature and (2rt2xrt2)R45 degrees low temperature structures (open access)

Alpha-Gallium (010) surface reconstruction: a LEED structural analysis of the (1x1) room temperature and (2rt2xrt2)R45 degrees low temperature structures

The geometric structure of the alpha-Ga(010)-(1x1) room temperature structure and its (2rt2xrt2) R45 degrees reconstruction below 232 K have been determined using Low Energy Electron Diffraction (LEED) structure analysis. The room temperature structure conforms to the cut-dimer model, forming a two-dimensional metallic structure with only minimal lateral displacements of the atoms. The topmost interlayer distance is 1.53 Angstrom, corresponding to a spacing expansion of 2 percent from the bulk. In the low-temperature structure, the surface atoms shift to dimerize within the top two layers, resulting in a network of mostly covalent bonds, which form both parallel and perpendicular to the surface plane. The bond lengths of some of these dimers are about 10 percent shorter than the bond length found in the alpha-Ga bulk and are thus shorter than any Ga-Ga bonds reported so far.
Date: February 28, 2003
Creator: More, S.; Soares, E. A.; Van Hove, M. A.; Lizzit, S.; Baraldi, A.; Grutter, Ch. et al.
System: The UNT Digital Library
Palomar 5 and its tidal tails: New observational results (open access)

Palomar 5 and its tidal tails: New observational results

Sloan Digital Sky Survey data for the field of the cluster Pal 5 reveal the existence of a long massive stream of tidal debris spanning an arc of 10{sup o} on the sky. Pal 5 thus provides an outstanding example for tidal disruption of globular clusters in the Milky Way. Radial velocities from VLT spectra show that Pal 5 has an extremely low velocity dispersion, in accordance with the very low mass derived from its total luminosity.
Date: February 6, 2003
Creator: al., M. Odenkirchen et
System: The UNT Digital Library
Novel secreted isoform of adhesion molecule ICAM-4: Potential regulator of membrane-associated ICAM-4 interactions (open access)

Novel secreted isoform of adhesion molecule ICAM-4: Potential regulator of membrane-associated ICAM-4 interactions

ICAM-4, a newly characterized adhesion molecule, is expressed early in human erythropoiesis and functions as a ligand for binding a4b1 and aV integrin-expressing cells. Within the bone marrow, erythroblasts surround central macrophages forming erythroblastic islands. Evidence suggests that these islands are highly specialized subcompartments where cell adhesion events, in concert with cytokines, play critical roles in regulating erythropoiesis and apoptosis. Since erythroblasts express a4b1 and ICAM-4 and macrophages exhibit aV, ICAM-4 is an attractive candidate for mediating cellular interactions within erythroblastic islands. To determine whether ICAM-4 binding properties are conserved across species, we first cloned and sequenced the murine homologue. The translated amino acid sequence showed 68 percent overall identity with human ICAM-4. Using recombinant murine ICAM-4 extracellular domains, we discovered that hematopoietic a4b1-expressing HEL cells and non-hematopoietic aV-expressing FLY cells adhered to mouse ICAM-4. Cell adhesion studies showed that FLY and HEL cells bound to mouse and human proteins with similar avidity. These data strongly suggest conservation of integrin-binding properties across species. Importantly, we characterized a novel second splice cDNA that would be predicted to encode an ICAM-4 isoform, lacking the membrane-spanning domain. Erythroblasts express both isoforms of ICAM-4. COS-7 cells transfected with GFP constructs of prototypic or novel …
Date: February 18, 2003
Creator: Lee, Gloria; Spring, Frances A.; Parons, Stephen F.; Mankelow, Tosti J.; Peters, Luanne L.; Koury, Mark J. et al.
System: The UNT Digital Library
The renewables portfolio standard in Texas: An early assessment (open access)

The renewables portfolio standard in Texas: An early assessment

None
Date: February 1, 2003
Creator: Langniss, Ole & Wiser, Ryan
System: The UNT Digital Library
Barrier RF stacking (open access)

Barrier RF stacking

This paper introduces a new method for stacking beams in the longitudinal phase space. It uses RF barriers to confine and compress beams in an accelerator, provided that the machine momentum acceptance is a few times larger than the momentum spread of the injected beam. This is the case for the Fermilab Main Injector. A barrier RF system employing Finemet cores and high-voltage solid-state switches is under construction. The goal is to double the number of protons per cycle on the production target for Run2 and NuMI experiments.
Date: February 24, 2003
Creator: Takagi, Weiren Chou and Akira
System: The UNT Digital Library
Analysis of the vaporization barrier above waste emplacement drifts (open access)

Analysis of the vaporization barrier above waste emplacement drifts

Prediction of the amount of water that may seep into the waste emplacement drifts is an important aspect of assessing the performance of the proposed geologic nuclear waste repository at Yucca Mountain, Nevada. The repository is to be located in thick, partially saturated fractured tuff that will be heated to above-boiling temperatures as a result of heat generation from the decay of nuclear waste. Since water percolating down towards the repository will be subject to vigorous boiling for a significant time period, the superheated rock zone (i.e., rock temperature above the boiling point of water) can form an effective vaporization barrier that reduces the possibility of water arrival at emplacement drifts. In this paper, we analyze the behavior of episodic preferential flow events that penetrate the hot fractured rock, and we evaluate the impact of such flow behavior on the effectiveness of the vaporization barrier.
Date: February 3, 2003
Creator: Birkholzer, Jens; Mukhopadhyay, Sumit & Tsang, Yvonne
System: The UNT Digital Library
The Fermilab data storage infrastructure (open access)

The Fermilab data storage infrastructure

Fermilab, in collaboration with the DESY laboratory in Hamburg, Germany, has created a petabyte scale data storage infrastructure to meet the requirements of experiments to store and access large data sets. The Fermilab data storage infrastructure consists of the following major storage and data transfer components: Enstore mass storage system, DCache distributed data cache, ftp and Grid ftp for primarily external data transfers. This infrastructure provides a data throughput sufficient for transferring data from experiments' data acquisition systems. It also allows access to data in the Grid framework.
Date: February 6, 2003
Creator: Bakken, Jon A.; Berman, Eileen; Huang, Chih-Hao; Moibenko, Alexander; Petravick, Donald & Zalokar, Michael
System: The UNT Digital Library
Near Real Time Characterization of BNL Stockpiled Soils, Another ASTD Success Story (open access)

Near Real Time Characterization of BNL Stockpiled Soils, Another ASTD Success Story

As of October 2001, approximately 7,000 yd{sup 3} of stockpiled soil, contaminated to varying degrees with radioactive materials and heavy metals, remained at Brookhaven National Laboratory (BNL) after the remediation of the BNL Chemical/Animal/Glass Pits disposal area. During the 1997 removal action, the more hazardous/radioactive materials were segregated, along with, chemical liquids and solids, animal carcasses, intact gas cylinders, and a large quantity of metal and glass debris. Nearly all of these materials have been disposed of. In order to ensure that all debris was removed and to characterize the large quantity of heterogeneous soil, BNL initiated an extended sorting, segregation, and characterization project, co-funded by the BNL Environmental Management Directorate and the DOE EM Office of Science and Technology Accelerated Site Technology Deployment (ASTD) program. Project objectives were to remove any non-conforming items, and to assure that mercury and radioactive contaminant levels were within acceptable limits for disposal as low-level radioactive waste. Sorting and segregation were conducted simultaneously. Large stockpiles, ranging from 150 to 1,200 yd{sup 3}, were subdivided into manageable 20 yd{sup 3} ''subpiles'' after powered vibratory screening. The 1/2 inch screen removed gravel and almost all non-conforming items, which were separated for further characterization. Soil that passed …
Date: February 23, 2003
Creator: Bowerman, B. S.; Adams, J. W.; Kalb, P. D. & Lockwood, A.
System: The UNT Digital Library
Effects of Point Sources in Trench Disposal of Radioactive Waste (open access)

Effects of Point Sources in Trench Disposal of Radioactive Waste

At the U. S. Department of Energy Savannah River Site, disposal of radioactive wastes in shallow trenches was simulated with vadose zone models and decoupled aquifer models. The vadose zone models provided contaminant fluxes to the aquifer models.
Date: February 5, 2003
Creator: Collard, L.B.
System: The UNT Digital Library
Microbial Forensics: A Scientific Assessment (open access)

Microbial Forensics: A Scientific Assessment

Microorganisms have been used as weapons in criminal acts, most recently highlighted by the terrorist attack using anthrax in the fall of 2001. Although such ''biocrimes'' are few compared with other crimes, these acts raise questions about the ability to provide forensic evidence for criminal prosecution that can be used to identify the source of the microorganisms used as a weapon and, more importantly, the perpetrator of the crime. Microbiologists traditionally investigate the sources of microorganisms in epidemiological investigations, but rarely have been asked to assist in criminal investigations. A colloquium was convened by the American Academy of Microbiology in Burlington, Vermont, on June 7-9, 2002, in which 25 interdisciplinary, expert scientists representing evolutionary microbiology, ecology, genomics, genetics, bioinformatics, forensics, chemistry, and clinical microbiology, deliberated on issues in microbial forensics. The colloquium's purpose was to consider issues relating to microbial forensics, which included a detailed identification of a microorganism used in a bioattack and analysis of such a microorganism and related materials to identify its forensically meaningful source--the perpetrators of the bioattack. The colloquium examined the application of microbial forensics to assist in resolving biocrimes with a focus on what research and education are needed to facilitate the use of …
Date: February 17, 2003
Creator: Keim, Paul
System: The UNT Digital Library
CDF Run II status and prospects (open access)

CDF Run II status and prospects

Run II at the Tevatron Collider started at the beginning of March 2001. With extensive upgrades on both detectors and electronics the CDF II began to collect data. This paper reviews early Run II physics results obtained by analyzing data collected before the middle of June 2002. At the present the understanding of the detector performances is rather high so many analysis are already underway.
Date: February 6, 2003
Creator: Pagliarone, C.
System: The UNT Digital Library
Future of B Physics at CDF and D0 (open access)

Future of B Physics at CDF and D0

In this contribution to the panel discussion on ''The Future of Hadron B Experiments'' held at the 8th International Conference on B Physics at Hadron Machines (Beauty 2002) at Santiago de Compostela, Spain, June 17-21, 2002, we explore the physics potential for B physics at CDF and D0 in five years and beyond. After a brief introduction to precision flavour physics, we concentrate our discussion on the future of CP violation by evaluating the prospects for measuring the CKM angles {beta}, {gamma} and {alpha} at the Tevatron Collider experiments CDF and D0 by the end of Run II.
Date: February 21, 2003
Creator: Paulini, M.
System: The UNT Digital Library
Multi-criteria decision analysis: Limitations, pitfalls, and practical difficulties (open access)

Multi-criteria decision analysis: Limitations, pitfalls, and practical difficulties

The 2002 Winter Olympics women's figure skating competition is used as a case study to illustrate some of the limitations, pitfalls, and practical difficulties of Multi-Criteria Decision Analysis (MCDA). The paper compares several widely used models for synthesizing the multiple attributes into a single aggregate value. The various MCDA models can provide conflicting rankings of the alternatives for a common set of information even under states of certainty. Analysts involved in MCDA need to deal with the following challenging tasks: (1) selecting an appropriate analysis method, and (2) properly interpreting the results. An additional trap is the availability of software tools that implement specific MCDA models that can beguile the user with quantitative scores. These conclusions are independent of the decision domain and they should help foster better MCDA practices in many fields including systems engineering trade studies.
Date: February 1, 2003
Creator: Kujawski, Edouard
System: The UNT Digital Library
Focal-series reconstruction of nanoparticle exit-surface electron wave (open access)

Focal-series reconstruction of nanoparticle exit-surface electron wave

We have used the One-Angstrom Microscope (OAM) to image and apply focal-series reconstruction (FSR) of the exit-surface wave (ESW) to a 70Angstrom particle of gold supported on amorphous carbon. The phase of the complex ESW shows the positions of the atom columns in the specimen as white dots, and its diffractogram shows it contains information to 1.23Angstrom. The result demonstrates that through-focal reconstruction of the ESW does not need large crystal expanses to work properly. Although [110] Au structures may not need sub-Angstrom resolution to show all the useful structural details of the particle in this orientation, it is clear that focal reconstruction of the ESW can improve original data that is much more difficult to interpret directly. We expect this technique to prove even more useful when applied to nanoparticles containing finer spacings than the 2.35Angstrom separation of the 111 planes in the present gold nano-particle.
Date: February 24, 2003
Creator: O'Keefe, Michael A.; Nelson, E. Chris & Allard, Lawrence F.
System: The UNT Digital Library
HRTEM at half-Angstrom resolution: From OAM to TEAM (open access)

HRTEM at half-Angstrom resolution: From OAM to TEAM

Transmission electron microscopy (TEM) at sub-Angstrom resolution is important for nanotechnology. Identifying atom positions requires appropriate resolution, the ability to separate distinct objects in images. With Cs corrected, the information limit of the TEM controls resolution. The OAM has demonstrated that a resolution of 0.78A is possible. The TEAM (transmission electron achromatic microscope) will be a TEM using hardware correction of Cs with a monochromator to improve its information limit beyond that of the OAM by improvement of the electron-beam energy spread. It is shown that A 300keV HRTEM TEAM does not require a Cc corrector to reach 0.5A as long as beam energy spread and objective-lens current ripple are lowered sufficiently. A lower-voltage TEAM will require stricter limits on objective-lens current ripple to reach the targeted 0.5A resolution. No improvement in HT ripple or noise is required to improve the information limit per se since the monochromator determines the energy spread in the beam. However, improved HT ripple and noise will improve the beam current statistics (number of electrons passing through the monochromator) by placing more of the electrons closer to the center of the energy-spread distribution
Date: February 17, 2003
Creator: O'Keefe, Michael A.
System: The UNT Digital Library
Integration of health physics, safety and operational processes for management and disposition of recycled uranium wastes at the Fernald Environmental Management Project (FEMP) (open access)

Integration of health physics, safety and operational processes for management and disposition of recycled uranium wastes at the Fernald Environmental Management Project (FEMP)

Fluor Fernald, Inc. (Fluor Fernald), the contractor for the U. S. Department of Energy (DOE) Fernald Environmental Management Project (FEMP), recently submitted a new baseline plan for achieving site closure by the end of calendar year 2006. This plan was submitted at DOE's request, as the FEMP was selected as one of the sites for their accelerated closure initiative. In accordance with the accelerated baseline, the FEMP Waste Management Project (WMP) is actively evaluating innovative processes for the management and disposition of low-level uranium, fissile material, and thorium, all of which have been classified as waste. These activities are being conducted by the Low Level Waste (LLW) and Uranium Waste Disposition (UWD) projects. Alternatives associated with operational processing of individual waste streams, each of which poses potentially unique health physics, industrial hygiene and industrial hazards, are being evaluated for determination of the most cost effective and safe met hod for handling and disposition. Low-level Mixed Waste (LLMW) projects are not addressed in this paper. This paper summarizes historical uranium recycling programs and resultant trace quantity contamination of uranium waste streams with radionuclides, other than uranium. The presentation then describes how waste characterization data is reviewed for radiological and/or chemical hazards …
Date: February 23, 2003
Creator: Barber, James & Buckley, James
System: The UNT Digital Library
The role of hydromechanical coupling in fractured rock engineering (open access)

The role of hydromechanical coupling in fractured rock engineering

None
Date: February 27, 2003
Creator: Rutqvist, Jonny & Stephansson, Ove
System: The UNT Digital Library
Rheology Modifiers for Radioactive Waste Slurries (open access)

Rheology Modifiers for Radioactive Waste Slurries

The goals of this study were to determine if trace levels of chemical additives could be used to reduce the rheological characteristics of radioactive waste slurries, identify potential chemical additives for this work and future testing, test a limited set of chemical additive candidates on simulated radioactive wastes, and develop advanced techniques to visualize the internal slurry structure and particle-particle interaction within the slurry.
Date: February 19, 2003
Creator: Calloway, T.B. Jr.
System: The UNT Digital Library
Introduction to heavy meson decays and CP asymmetries (open access)

Introduction to heavy meson decays and CP asymmetries

These lectures are intended to provide an introduction to heavy meson decays and CP violation. The first lecture contains a brief review of the standard model and how the CKM matrix and CP violation arise, mixing and CP violation in neutral meson systems, and explanation of the cleanliness of the sin 2{beta} measurement. The second lecture deals with the heavy quark limit, some applications of heavy quark symmetry and the operator product expansion for exclusive and inclusive semileptonic B decays. The third lecture concerns with theoretically clean CP violation measurements that may become possible in the future, and some developments toward a better understanding of nonleptonic B decays. The conclusions include a subjective best buy list for the near future.
Date: February 5, 2003
Creator: Ligeti, Zoltan
System: The UNT Digital Library
Uptake and Retention of Cs137 by a Blue-Green Alga in Continuous Flow and Batch Culture Systems (open access)

Uptake and Retention of Cs137 by a Blue-Green Alga in Continuous Flow and Batch Culture Systems

Since routine monitoring data show that blue-green algae concentrate radioactivity from water by factors as great as 10,000, this study was initiated to investigate the uptake and retention patterns of specific radionuclides by the dominant genera of blue-green algae in the reactor effluents. Plectonema purpureum was selected for this study.
Date: February 18, 2003
Creator: Watts, J. R.
System: The UNT Digital Library