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Aberration-Coreected Electron Microscopy at Brookhaven National Laboratory (open access)

Aberration-Coreected Electron Microscopy at Brookhaven National Laboratory

The last decade witnessed the rapid development and implementation of aberration correction in electron optics, realizing a more-than-70-year-old dream of aberration-free electron microscopy with a spatial resolution below one angstrom [1-9]. With sophisticated aberration correctors, modern electron microscopes now can reveal local structural information unavailable with neutrons and x-rays, such as the local arrangement of atoms, order/disorder, electronic inhomogeneity, bonding states, spin configuration, quantum confinement, and symmetry breaking [10-17]. Aberration correction through multipole-based correctors, as well as the associated improved stability in accelerating voltage, lens supplies, and goniometers in electron microscopes now enables medium-voltage (200-300kV) microscopes to achieve image resolution at or below 0.1nm. Aberration correction not only improves the instrument's spatial resolution but, equally importantly, allows larger objective lens pole-piece gaps to be employed thus realizing the potential of the instrument as a nanoscale property-measurement tool. That is, while retaining high spatial resolution, we can use various sample stages to observe the materials response under various temperature, electric- and magnetic- fields, and atmospheric environments. Such capabilities afford tremendous opportunities to tackle challenging science and technology issues in physics, chemistry, materials science, and biology. The research goal of the electron microscopy group at the Dept. of Condensed Matter Physics and …
Date: April 1, 2008
Creator: Zhu, Y. & Wall, J.
System: The UNT Digital Library
ACCELERATED PROCESSING OF SB4 AND PREPARATION FOR SB5 PROCESSING AT DWPF (open access)

ACCELERATED PROCESSING OF SB4 AND PREPARATION FOR SB5 PROCESSING AT DWPF

The Defense Waste Processing Facility (DWPF) initiated processing of Sludge Batch 4 (SB4) in May 2007. SB4 was the first DWPF sludge batch to contain significant quantities of HM or high Al sludge. Initial testing with SB4 simulants showed potential negative impacts to DWPF processing; therefore, Savannah River National Laboratory (SRNL) performed extensive testing in an attempt to optimize processing. SRNL's testing has resulted in the highest DWPF production rates since start-up. During SB4 processing, DWPF also began incorporating waste streams from the interim salt processing facilities to initiate coupled operations. While DWPF has been processing SB4, the Liquid Waste Organization (LWO) and the SRNL have been preparing Sludge Batch 5 (SB5). SB5 has undergone low-temperature aluminum dissolution to reduce the mass of sludge for vitrification and will contain a small fraction of Purex sludge. A high-level review of SB4 processing and the SB5 preparation studies will be provided.
Date: December 1, 2008
Creator: Herman, C
System: The UNT Digital Library
Anisotropic Hexagonal Boron Nitride Nanomaterials - Synthesis and Applications (open access)

Anisotropic Hexagonal Boron Nitride Nanomaterials - Synthesis and Applications

Boron nitride (BN) is a synthetic binary compound located between III and V group elements in the Periodic Table. However, its properties, in terms of polymorphism and mechanical characteristics, are rather close to those of carbon compared with other III-V compounds, such as gallium nitride. BN crystallizes into a layered or a tetrahedrally linked structure, like those of graphite and diamond, respectively, depending on the conditions of its preparation, especially the pressure applied. Such correspondence between BN and carbon readily can be understood from their isoelectronic structures [1, 2]. On the other hand, in contrast to graphite, layered BN is transparent and is an insulator. This material has attracted great interest because, similar to carbon, it exists in various polymorphic forms exhibiting very different properties; however, these forms do not correspond strictly to those of carbon. Crystallographically, BN is classified into four polymorphic forms: Hexagonal BN (h-BN) (Figure 1(b)); rhombohedral BN (r-BN); cubic BN (c-BN); and wurtzite BN (w-BN). BN does not occur in nature. In 1842, Balmain [3] obtained BN as a reaction product between molten boric oxide and potassium cyanide under atmospheric pressure. Thereafter, many methods for its synthesis were reported. h-BN and r-BN are formed under ambient …
Date: August 1, 2008
Creator: Han,W.Q.
System: The UNT Digital Library
Bacteria in Permafrost (open access)

Bacteria in Permafrost

Significant numbers of viable ancient microorganisms are known to be present within the permafrost. They have been isolated in both polar regions from the cores up to 400 m deep and ground temperatures of -27 C. The age of the cells corresponds to the longevity of the permanently frozen state of the soils, with the oldest cells dating back to {approx}3 million years in the Arctic, and {approx}5 million years in the Antarctic. They are the only life forms known to have retained viability over geological time. Thawing of the permafrost renews their physiological activity and exposes ancient life to modern ecosystems. Thus, the permafrost represents a stable and unique physicochemical complex, which maintains life incomparably longer than any other known habitats. If we take into account the depth of the permafrost layers, it is easy to conclude that they contain a total microbial biomass many times higher than that of the soil cover. This great mass of viable matter is peculiar to permafrost only.
Date: January 1, 2008
Creator: Gilichinsky, David A.; Vishnivetskaya, Tatiana A.; Petrova, Maya A.; Spirina, Elena V.; Mamikin, Vladimir & Rivkina, Elizaveta
System: The UNT Digital Library
Chapter 2: Sustainable and Unsustainable Developments in the U.S. Energy System (open access)

Chapter 2: Sustainable and Unsustainable Developments in the U.S. Energy System

Over the course of the nineteenth and twentieth centuries, the United States developed a wealthy society on the basis of cheap and abundant fossil fuel energy. As fossil fuels have become ecologically and economically expensive in the twenty-first century, America has shown mixed progress in transitioning to a more sustainable energy system. From 2000 to 2006, energy and carbon intensity of GDP continued favorable long-term trends of decline. Energy end-use efficiency also continued to improve; for example, per-capita electricity use was 12.76 MWh per person per year in 2000 and again in 2006, despite 16 percent GDP growth over that period. Environmental costs of U.S. energy production and consumption have also been reduced, as illustrated in air quality improvements. However, increased fossil fuel consumption, stagnant efficiency standards, and expanding corn-based ethanol production have moved the energy system in the opposite direction, toward a less sustainable energy system. This chapter reviews energy system developments between 2000 and 2006 and presents policy recommendations to move the United States toward a more sustainable energy system.
Date: May 1, 2008
Creator: Levine, Mark; Levine, Mark D. & Aden, Nathaniel T.
System: The UNT Digital Library
The Exosporium of B.cereus Contains a Binding Site for gC1qR/p33: Implication in Spore Attachment and/or Entry (open access)

The Exosporium of B.cereus Contains a Binding Site for gC1qR/p33: Implication in Spore Attachment and/or Entry

B. cereus, is a member of a genus of aerobic, gram-positive, spore-forming rod-like bacilli, which includes the deadly, B. anthracis. Preliminary experiments have shown that gC1qR binds to B.cereus spores that have been attached to microtiter plates. The present studies were therefore undertaken, to examine if cell surface gC1qR plays a role in B.cereus spore attachment and/or entry. Monolayers of human colon carcinoma (Caco-2) and lung cells were grown to confluency on 6 mm coverslips in shell vials with gentle swirling in a shaker incubator. Then, 2 {micro}l of a suspension of strain SB460 B.cereus spores (3x10{sup 8}/ml, in sterile water), were added and incubated (1-4 h; 36{sup 0} C) in the presence or absence of anti-gC1qR mAb-carbon nanoloops. Examination of these cells by EM revealed that: (1) When B. cereus endospores contacted the apical Caco-2 cell surface, or lung cells, gClqR was simultaneously detectable, indicating upregulation of the molecule. (2) In areas showing spore contact with the cell surface, gClqR expression was often adjacent to the spores in association with microvilli (Caco-2 cells) or cytoskeletal projections (lung cells). (3) Furthermore, the exosporia of the activated and germinating spores were often decorated with mAb-nanoloops. These observations were further corroborated by …
Date: January 1, 2008
Creator: Ghebrehiwet, Berhane; Tantral, Lee; Titmus, Matthew A.; Panessa-Warren, Barbara J.; Tortora, George T.; Wong, Stanislaus S. et al.
System: The UNT Digital Library
MSTD 2007 Publications and Patents (open access)

MSTD 2007 Publications and Patents

The Materials Science and Technology Division (MSTD) supports the central scientific and technological missions of the Laboratory, and at the same time, executes world-class, fundamental research and novel technological development over a wide range of disciplines. Our organization is driven by the institutional needs in nuclear weapons stockpile science, high-energy-density science, nuclear reactor science, and energy and environment science and technology. We maintain expertise and capabilities in many diverse areas, including actinide science, electron microscopy, laser-materials interactions, materials theory, simulation and modeling, materials synthesis and processing, materials science under extreme conditions, ultrafast materials science, metallurgy, nanoscience and technology, nuclear fuels and energy security, optical materials science, and surface science. MSTD scientists play leadership roles in the scientific community in these key and emerging areas.
Date: April 1, 2008
Creator: King, W. E.
System: The UNT Digital Library
Philosophy of Mind and the Problem of FreeWill in the Light of Quantum Mechanics. (open access)

Philosophy of Mind and the Problem of FreeWill in the Light of Quantum Mechanics.

Arguments pertaining to the mind-brain connection and to the physical effectiveness of our conscious choices have been presented in two recent books, one by John Searle, the other by Jaegwon Kim. These arguments are examined, and it is argued that the difficulties encountered arise from a defective understanding and application of a pertinent part of contemporary science, namely quantum mechanics.
Date: April 1, 2008
Creator: Stapp, Henry & Stapp, Henry P
System: The UNT Digital Library
POPULATION DISTRIBUTION DURING THE DAY (open access)

POPULATION DISTRIBUTION DURING THE DAY

Population distribution during the day can be defined as distribution of population in an area during the daytime hours. However, a precise definition of daytime hours is challenging given the geographic variability in the length of a day or daylight hours. The US Census Bureau used "normal business hours" as the span of time to describe daytime population. Given that Censuses typically estimates residential population, it represents a nighttime population distribution. In that respect, daytime population in an area may be broadly defined as distribution of population at times other than when they are expected to be at their residences at night which extends the duration from business hours to include the evening hours as well.
Date: January 1, 2008
Creator: Bhaduri, Budhendra L.
System: The UNT Digital Library
Population Evacuations (open access)

Population Evacuations

Emergency evacuation is one of the most important protective action alternatives when facing a natural or a man-made disaster. The planning and implementation of a large-scale emergency evacuation is a difficult and complex problem that requires the interactions of many agencies and involves a large amount of information. This article focuses on the latter and discusses the models that are normally used in the planning phase to evaluate this type of protective action alternatives and the information requirements for their implementation. Although many advances have been achieved in this area, especially during the last few years, a considerable amount of work still remains incomplete. Some of the important areas that need attention, such as improvements in the demographic models, integration of traffic simulation and threat evolution models, and real-time information for the deployment phase, are also discussed in this paper.
Date: January 1, 2008
Creator: Franzese, Oscar
System: The UNT Digital Library
Proceedings of the 4th Annual Workshop on Cyber Security and Information Intelligence Research: Developing Strategies To Meet The Cyber Security And Information Intelligence Challenges Ahead (open access)

Proceedings of the 4th Annual Workshop on Cyber Security and Information Intelligence Research: Developing Strategies To Meet The Cyber Security And Information Intelligence Challenges Ahead

As our dependence on the cyber infrastructure grows ever larger, more complex and more distributed, the systems that compose it become more prone to failures and/or exploitation. Intelligence is information valued for its currency and relevance rather than its detail or accuracy. Information explosion describes the pervasive abundance of (public/private) information and the effects of such. Gathering, analyzing, and making use of information constitutes a business- / sociopolitical- / military-intelligence gathering activity and ultimately poses significant advantages and liabilities to the survivability of "our" society. The combination of increased vulnerability, increased stakes and increased threats make cyber security and information intelligence (CSII) one of the most important emerging challenges in the evolution of modern cyberspace "mechanization." The goal of the workshop was to challenge, establish and debate a far-reaching agenda that broadly and comprehensively outlined a strategy for cyber security and information intelligence that is founded on sound principles and technologies. We aimed to discuss novel theoretical and applied research focused on different aspects of software security/dependability, as software is at the heart of the cyber infrastructure.
Date: January 1, 2008
Creator: Sheldon, Frederick T; Krings, Axel; Abercrombie, Robert K & Mili, Ali
System: The UNT Digital Library
Rapid Data Assimilation in the Indoor Environment: theory and examples from real-time interpretation of indoor plumes of airborne chemicals (open access)

Rapid Data Assimilation in the Indoor Environment: theory and examples from real-time interpretation of indoor plumes of airborne chemicals

Releases of acutely toxic airborne contaminants in or near a building can lead to significant human exposures unless prompt response measures are identified and implemented. Commonly, possible responses include conflicting strategies, such as shutting the ventilation system off versus running it in a purge (100percent outside air) mode, or having occupants evacuate versus sheltering in place. The right choice depends in part on quickly identifying the source locations, the amounts released, and the likely future dispersion routes of the pollutants. This paper summarizes recent developments to provide such estimates in real time using an approach called Bayesian Monte Carlo updating. This approach rapidly interprets measurements of airborne pollutant concentrations from multiple sensors placed in the building and computes best estimates and uncertainties of the release conditions. The algorithm is fast, capable of continuously updating the estimates as measurements stream in from sensors. The approach is employed, as illustration, to conduct two specific investigations under different situations.
Date: September 1, 2008
Creator: Gadgil, Ashok; Sohn, Michael & Sreedharan, Priya
System: The UNT Digital Library
Theoretical Studies in Heterogenous Catalysis: Towards a Rational Design of Novel Catalysts for Hydrodesulfurization and Hydrogen Production (open access)

Theoretical Studies in Heterogenous Catalysis: Towards a Rational Design of Novel Catalysts for Hydrodesulfurization and Hydrogen Production

Traditionally, knowledge in heterogeneous catalysis has come through empirical research. Nowadays, there is a clear interest to change this since millions of dollars in products are generated every year in the chemical and petrochemical industries through catalytic processes. To obtain a fundamental knowledge of the factors that determine the activity of heterogeneous catalysts is a challenge for modern science since many of these systems are very complex in nature. In principle, when a molecule adsorbs on the surface of a heterogeneous catalyst, it can interact with a large number of bonding sites. It is known that the chemical properties of these bonding sites depend strongly on the chemical environment around them. Thus, there can be big variations in chemical reactivity when going from one region to another in the surface of a heterogeneous catalyst. A main objective is to understand how the structural and electronic properties of a surface affect the energetics for adsorption processes and the paths for dissociation and chemical reactions. In recent years, advances in instrumentation and experimental procedures have allowed a large series of detailed works on the surface chemistry of heterogeneous catalysts. In many cases, these experimental studies have shown interesting and unique phenomena. Theory …
Date: October 1, 2008
Creator: Rodriguez,J.A. & Liu, P.
System: The UNT Digital Library
Virtual Human Problem Solving Environments (open access)

Virtual Human Problem Solving Environments

Abstract. Interest in complex integrated digital or virtual human modeling has seen a significant increase over the last decade. Coincident with that increased interest, Oak Ridge National Laboratory (ORNL) initiated the development of a human simulation tool, the Virtual Human. The Virtual Human includes a problem-solving environment (PSE) for implementing the integration of physiological models in different programming languages and connecting physiological function to anatomy. The Virtual Human PSE (VHPSE) provides the computational framework with which to develop the concept of a "Virtual Human." Supporting the framework is a data definition for modeling parameters, PhysioML, a Virtual Human Database (VHDB), and a Web-based graphical user interface (GUI) developed using Java. Following description of the VHPSE, we discuss four example implementations of models within the framework. Further expansion of a human modeling environment was carried out in the Defense Advanced Research Projects Agency Virtual Soldier Project. SCIRun served as the Virtual Soldier problem solving environment (VSPSE). We review and compare specific developments in these projects that have significant potential for the future of Virtual Human modeling and simulation. We conclude with an evaluation of areas of future work that will provide important extensions to the VHPSE and VSPSE and make possible …
Date: January 1, 2008
Creator: Ward, Richard C.; Pouchard, Line Catherine; Munro, Nancy B. & Fischer, Sarah Kathleen
System: The UNT Digital Library