Application of NMR Methods to Identify Detection Reagents for Use in the Development of Robust Nanosensors (open access)

Application of NMR Methods to Identify Detection Reagents for Use in the Development of Robust Nanosensors

Nuclear Magnetic Resonance (NMR) spectroscopy is a powerful technique for studying bi-molecular interactions at the atomic scale. Our NMR lab is involved in the identification of small molecules, or ligands that bind to target protein receptors, such as tetanus (TeNT) and botulinum (BoNT) neurotoxins, anthrax proteins and HLA-DR10 receptors on non-Hodgkin's lymphoma cancer cells. Once low affinity binders are identified, they can be linked together to produce multidentate synthetic high affinity ligands (SHALs) that have very high specificity for their target protein receptors. An important nanotechnology application for SHALs is their use in the development of robust chemical sensors or biochips for the detection of pathogen proteins in environmental samples or body fluids. Here, we describe a recently developed NMR competition assay based on transferred nuclear Overhauser effect spectroscopy (trNOESY) that enables the identification of sets of ligands that bind to the same site, or a different site, on the surface of TeNT fragment C (TetC) than a known ''marker'' ligand, doxorubicin. Using this assay, we can identify the optimal pairs of ligands to be linked together for creating detection reagents, as well as estimate the relative binding constants for ligands competing for the same site.
Date: April 29, 2004
Creator: Cosman, M; Krishnan, V V & Balhorn, R
System: The UNT Digital Library
Bridging the Gap between Quantum Mechanics and Large-Scale Atomistic Simulation (open access)

Bridging the Gap between Quantum Mechanics and Large-Scale Atomistic Simulation

The prospect of modeling across disparate length and time scales to achieve a predictive multiscale description of real materials properties has attracted widespread research interest in the last decade. To be sure, the challenges in such multiscale modeling are many, and in demanding cases, such as mechanical properties or dynamic phase transitions, multiple bridges extending from the atomic level all the way to the continuum level must be built. Although often overlooked in this process, one of the most fundamental and important problems in multiscale modeling is that of bridging the gap between first-principles quantum mechanics, from which true predictive power for real materials emanates, and the large-scale atomistic simulation of thousands or millions of atoms, which is usually essential to describe the complex atomic processes that link to higher length and time scales. For example, to model single-crystal plasticity at micron length scales via dislocation-dynamics simulations that evolve the detailed dislocation microstructure requires accurate large-scale atomistic information on the mobility and interaction of individual dislocations. Similarly, modeling the kinetics of structural phase transitions requires linking accurate large-scale atomistic information on nucleation processes with higher length and time scale growth processes.
Date: August 16, 2004
Creator: Moriarty, J. A.
System: The UNT Digital Library
Potential energy sputtering of EUVL materials (open access)

Potential energy sputtering of EUVL materials

Of the many candidates employed for understanding the erosion of critical Extreme Ultraviolet Lithography (EUVL) components, potential energy damage remains relatively uninvestigated. Unlike the familiar kinetic energy sputtering, which is a consequence of the momentum transferred by an ion to atoms in the target, potential energy sputtering occurs when an ion rapidly collects charge from the target as it neutralizes. Since the neutralization energy of a singly charged ion is typically on the order of 10 eV, potential energy effects are generally neglected for low charge state ions, and hence the bulk of the sputtering literature. As an ion's charge state is increased, the potential energy (PE) increases rapidly, e.g. PE(Xe{sup 1+})= 11 eV, PE(Xe{sup 10+}) = 810 eV, PE(Xe{sup 20+}) = 4.6 keV, etc. By comparison, the binding energy of a single atom on a surface is typically about 5 eV, so even relatively inefficient energy transfer mechanisms can lead to large quantities of material being removed, e.g. 25% efficiency for Xe{sup 10+} corresponds to {approx} 40 atoms/ion. By comparison, singly charged xenon ions with {approx} 20 keV of kinetic energy sputter only about 5 atoms/ion at normal incidence, and less than 1 atom/ion at typical EUV source energies. …
Date: July 2, 2004
Creator: Pomeroy, J. M.; Ratliff, L. P.; Gillaspy, J. D. & Bajt, S.
System: The UNT Digital Library
Archaeofaunal insights on pinniped-human interactions in the northeastern Pacific (open access)

Archaeofaunal insights on pinniped-human interactions in the northeastern Pacific

Human exploitation of pinnipeds has considerable antiquity but shows increasing impacts on population numbers in the Holocene. Pinnipeds are a rich source of fat as well as protein. A few well-documented cases of regional extirpation of seals and sea lions by non-industrial peoples exist. The northeastern Pacific region, from southern California to Alaska, has yielded archaeological evidence for distributions and abundances of eared seals that differs markedly from historically documented biogeography. This is especially true of the northern fur seal (Callorhinus ursinus), among the most common pinnipeds in many archaeological sites from the Santa Barbara Channel area through to Kodiak Islands. This chapter reviews contemporary eared seal biogeography, evidence for the earlier timing and extent, of occurrence of northern fur seals along the northeastern Pacific coast, zooarchaeological and isotopic evidence for their foraging and probable maintenance of rookeries in lower latitudes, and for their disappearance from the southernmost part of their ancient distribution well before European contact. It also reviews ongoing debates over the behavioral ecology of ancient fur seals and over humans role in contributing to their disappearance.
Date: February 7, 2004
Creator: Gifford-Gonzales, D; Newsome, S; Koch, P; Guilderson, T; Snodgrass, J & Burton, R
System: The UNT Digital Library
Laser Fusion: The First Ten Years 1962-1972 (open access)

Laser Fusion: The First Ten Years 1962-1972

This account of the beginning of the program on laser fusion at Livermore in 1962, and its subsequent development during the decade ending in 1972, was originally prepared as a contribution to the January 1991 symposium 'Achievements in Physics' honoring Professor Keith Brueckner upon his retirement from the University of San Diego at La Jolla. It is a personal recollection of work at Livermore from my vantage point as its scientific leader, and of events elsewhere that I thought significant. This period was one of rapid growth in which the technology of high-power short-pulse lasers needed to drive the implosion of thermonuclear fuel to the temperature and density needed for ignition was developed, and in which the physics of the interaction of intense light with plasmas was explored both theoretically and experimentally.
Date: June 25, 2004
Creator: Kidder, R. E.
System: The UNT Digital Library
Solid Nitrogen at Extreme Conditions of High Pressure and Temperature (open access)

Solid Nitrogen at Extreme Conditions of High Pressure and Temperature

We review the phase diagram of nitrogen in a wide pressure and temperature range. Recent optical and x-ray diffraction studies at pressures up to 300 GPa and temperatures in excess of 1000 K have provided a wealth of information on the transformation of molecular nitrogen to a nonmolecular (polymeric) semiconducting and two new molecular phases. These newly found phases have very large stability (metastability) range. Moreover, two new molecular phases have considerably different orientational order from the previously known phases. In the iota phase (unlike most of other known molecular phases), N{sub 2} molecules are orientationally equivalent. The nitrogen molecules in the theta phase might be associated into larger aggregates, which is in line with theoretical predictions on polyatomic nitrogen.
Date: April 5, 2004
Creator: Goncharov, A. & Gregoryanz, E.
System: The UNT Digital Library
Program and Abstracts: DOE Solar Program Review Meeting 2004, 25--28 October 2004, Denver, Colorado (open access)

Program and Abstracts: DOE Solar Program Review Meeting 2004, 25--28 October 2004, Denver, Colorado

This booklet contains the agenda and abstracts for the 2004 U.S. DOE Solar Energy Technologies Program Review Meeting. The meeting was held in Denver, Colorado, October 25-28, 2004. More than 240 abstracts are contained in this publication. Topic areas for the research papers include laboratory research, program management, policy analysis, and deployment of solar technologies.
Date: October 1, 2004
Creator: unknown
System: The UNT Digital Library
Improving Steam System Performance: A Sourcebook for Industry (open access)

Improving Steam System Performance: A Sourcebook for Industry

A sourcebook designed to provide steam system users with a reference outlining opportunities to improve system performance and optimize energy efficiency in industrial energy systems.
Date: October 1, 2004
Creator: unknown
System: The UNT Digital Library
Energy Design Guidelines for High Performance Schools: Tropical Island Climates (open access)

Energy Design Guidelines for High Performance Schools: Tropical Island Climates

The Energy Design Guidelines for High Performance Schools--Tropical Island Climates provides school boards, administrators, and design staff with guidance to help them make informed decisions about energy and environmental issues important to school systems and communities. These design guidelines outline high performance principles for the new or retrofit design of your K-12 school in tropical island climates. By incorporating energy improvements into their construction or renovation plans, schools can significantly reduce energy consumption and costs.
Date: November 1, 2004
Creator: unknown
System: The UNT Digital Library
Vacuum Technology (open access)

Vacuum Technology

The environmental condition called vacuum is created any time the pressure of a gas is reduced compared to atmospheric pressure. On earth we typically create a vacuum by connecting a pump capable of moving gas to a relatively leak free vessel. Through operation of the gas pump the number of gas molecules per unit volume is decreased within the vessel. As soon as one creates a vacuum natural forces (in this case entropy) work to restore equilibrium pressure; the practical effect of this is that gas molecules attempt to enter the evacuated space by any means possible. It is useful to think of vacuum in terms of a gas at a pressure below atmospheric pressure. In even the best vacuum vessels ever created there are approximately 3,500,000 molecules of gas per cubic meter of volume remaining inside the vessel. The lowest pressure environment known is in interstellar space where there are approximately four molecules of gas per cubic meter. Researchers are currently developing vacuum technology components (pumps, gauges, valves, etc.) using micro electro mechanical systems (MEMS) technology. Miniature vacuum components and systems will open the possibility for significant savings in energy cost and will open the doors to advances in …
Date: October 15, 2004
Creator: Biltoft, P. J.
System: The UNT Digital Library
System Performance Characterization (open access)

System Performance Characterization

Characterizing an adaptive optics (AO) system refers to understanding its performance and limitations. The goal of an AO system is to correct wavefront aberrations. The uncorrected aberrations, called the residual errors and referred to in what follows simply as the errors, degrade the image quality in the science camera. Understanding the source of these errors is a great aid in designing an AO system and optimizing its performance. This chapter explains how to estimate the wavefront error terms and the relationship between the wavefront error and the degradation of the image. The analysis deals with the particular case of a HartmannShack wavefront sensor (WFS) and a continuous deformable mirror (DM), although the principles involved can be applied to any AO system.
Date: May 26, 2004
Creator: van Dam, M. A.
System: The UNT Digital Library
Extended Community: An Oral History of the Community Environmental Monitoring Program (CEMP), 1989 - 2003 (open access)

Extended Community: An Oral History of the Community Environmental Monitoring Program (CEMP), 1989 - 2003

Studying the Community Environmental Monitoring Program (CEMP) provides a unique opportunity to trace a concept created by two nuclear industry originators from inception, as it transitioned through several stewardship agencies, to management by a non-profit organization. This transition is informed not only by changes over two decades in the views of the general populace toward nuclear testing but also by changing political climates and public policies. Several parallel histories accompanied the development of the CEMP: an administrative history, an environmental history, and a history of changing public perception of not only nuclear testing, but other activities involving radiation such as waste transportation, as well. Although vital, those histories will be provided only as background to the subject of this study, the oral histories gathered in this project. The oral histories collected open a window into the nuclear testing history of Nevada and Utah that has not heretofore been opened. The nuclear industry has generated a great deal of positive and negative reaction since its inception. The CEMP emerged with specific objectives. It was designed to provide information to potential downwind communities and counter negative perceptions by creating more community involvement and education about the testing. The current objectives of the …
Date: July 1, 2004
Creator: DeSilva, Susan
System: The UNT Digital Library
Corrosion Behavior of Nickel Alloys in Wet Hydrofluoric Acid (open access)

Corrosion Behavior of Nickel Alloys in Wet Hydrofluoric Acid

Hydrofluoric acid is a water solution of hydrogen fluoride (HF). Hydrofluoric acid is used widely in diverse types of industrial applications; traditionally, it is used in pickling solutions in the metal industry, in the fabrication of chlorofluorocarbon compounds, as an alkylation agent for gasoline and as an etching agent in the industry of glass. In recent years, hydrofluoric acid has extensively been used in the manufacture of semiconductors and microelectronics during the wet chemical cleaning of silicon wafers. Hydrofluoric acid can be considered a reducing acid and although it is chemically classified as weaker than, for example, sulfuric or hydrochloric acids, it is extremely corrosive. This acid is also particularly toxic and poses greater health hazard than most other acids. The corrosion behavior of metals in hydrofluoric acid has not been as systematic studied in the laboratory as for other common inorganic acids. This is largely because tests using hydrofluoric acid cannot be run in standard equipment and because of the toxic nature of this acid. Moreover, short-term weight loss laboratory corrosion tests in hydrofluoric acid can be frustrating since the results are not as highly reproducible as in the case of other acids such as sulfuric or hydrochloric. One …
Date: February 6, 2004
Creator: Rebak, R. B.
System: The UNT Digital Library
Spectroscopy of ions using fast beams and ion traps (open access)

Spectroscopy of ions using fast beams and ion traps

A knowledge of the spectra of ionized atoms is of importance in many fields. They can be studied in a wide variety of light sources. In recent years techniques coming under the broad heatings of fast beams and ion traps have been used extensively for such investigations. This article considers the advantages that various techniques have for particular applications.
Date: October 1, 2004
Creator: Pinnington, E. H. & Trabert, E.
System: The UNT Digital Library
Modelling the Madden Julian Oscillation (open access)

Modelling the Madden Julian Oscillation

The MJO has long been an aspect of the global climate that has provided a tough test for the climate modelling community. Since the 1980s there have been numerous studies of the simulation of the MJO in atmospheric general circulation models (GCMs), ranging from Hayashi and Golder (1986, 1988) and Lau and Lau (1986), through to more recent studies such as Wang and Schlesinger (1999) and Wu et al. (2002). Of course, attempts to reproduce the MJO in climate models have proceeded in parallel with developments in our understanding of what the MJO is and what drives it. In fact, many advances in understanding the MJO have come through modeling studies. In particular, failure of climate models to simulate various aspects of the MJO has prompted investigations into the mechanisms that are important to its initiation and maintenance, leading to improvements both in our understanding of, and ability to simulate, the MJO. The initial focus of this chapter will be on modeling the MJO during northern winter, when it is characterized as a predominantly eastward propagating mode and is most readily seen in observations. Aspects of the simulation of the MJO will be discussed in the context of its sensitivity …
Date: May 21, 2004
Creator: Slingo, J. M.; Inness, P. M. & Sperber, K. R.
System: The UNT Digital Library
A multi-scale approach to molecular dynamics simulations of shock waves (open access)

A multi-scale approach to molecular dynamics simulations of shock waves

Study of the propagation of shock waves in condensed matter has led to new discoveries ranging from new metastable states of carbon [1] to the metallic conductivity of hydrogen in Jupiter, [2] but progress in understanding the microscopic details of shocked materials has been extremely difficult. Complications can include the unexpected formation of metastable states of matter that determine the structure, instabilities, and time-evolution of the shock wave. [1,3] The formation of these metastable states can depend on the time-dependent thermodynamic pathway that the material follows behind the shock front. Furthermore, the states of matter observed in the shock wave can depend on the timescale on which observation is made. [4,1] Significant progress in understanding these microscopic details has been made through molecular dynamics simulations using the popular non-equilibrium molecular dynamics (NEMD) approach to atomistic simulation of shock compression. [5] The NEMD method involves creating a shock at one edge of a large system by assigning some atoms at the edge a fixed velocity. The shock propagates across the computational cell to the opposite side. The computational work required by NEMD scales at least quadratically in the evolution time because larger systems are needed for longer simulations to prevent the …
Date: September 3, 2004
Creator: Reed, E. J.; Fried, L. E.; Manaa, M. R. & Joannopoulos, J. D.
System: The UNT Digital Library
High Pressure Materials Research: Novel Extended Phases of Molecular Triatomics (open access)

High Pressure Materials Research: Novel Extended Phases of Molecular Triatomics

Application of high pressure significantly alters the interatomic distance and thus the nature of intermolecular interaction, chemical bonding, molecular configuration, crystal structure, and stability of solid [1]. With modern advances in high-pressure technologies [2], it is feasible to achieve a large (often up to a several-fold) compression of lattice, at which condition material can be easily forced into a new physical and chemical configuration [3]. The high-pressure thus offers enhanced opportunities to discover new phases, both stable and metastable ones, and to tune exotic properties in a wide-range of atomistic length scale, substantially greater than (often being several orders of) those achieved by other thermal (varying temperatures) and chemical (varying composition or making alloys) means. Simple molecular solids like H{sub 2}, C, CO{sub 2}, N{sub 2}, O{sub 2}, H{sub 2}O, CO, NH{sub 3}, and CH{sub 4} are bounded by strong covalent intramolecular bonds, yet relatively weak intermolecular bonds of van der Waals and/or hydrogen bonds. The weak intermolecular bonds make these solids highly compressible (i.e., low bulk moduli typically less than 10 GPa), while the strong covalent bonds make them chemically inert at least initially at low pressures. Carbon-carbon single bonds, carbon-oxygen double bonds and nitrogen-nitrogen triple bonds, for example, …
Date: May 26, 2004
Creator: Yoo, C.
System: The UNT Digital Library
Hyperspectral Geobotanical Remote Sensing for CO2 Storage Monitoring (open access)

Hyperspectral Geobotanical Remote Sensing for CO2 Storage Monitoring

This project's goal is to develop remote sensing methods for early detection and spatial mapping, over whole regions simultaneously, of any surface areas under which there are significant CO2 leaks from deep underground storage formations. If large amounts of CO2 gas percolated up from a storage formation below to within plant root depth of the surface, the CO2 soil concentrations near the surface would become elevated and would affect individual plants and their local plant ecologies. Excessive soil CO2 concentrations are observed to significantly affect local plant and animal ecologies in our geothermal exploration, remote sensing research program at Mammoth Mountain CA USA. We also know from our geothermal exploration remote sensing programs, that we can map subtle hidden faults by spatial signatures of altered minerals and of plant species and health distributions. Mapping hidden faults is important because in our experience these highly localized (one to several centimeters) spatial pathways are good candidates for potentially significant CO2 leaks from deep underground formations. The detection and discrimination method we are developing uses primarily airborne hyperspectral, high spatial (3 meter) with 128 band wavelength resolution, visible and near infrared reflected light imagery. We also are using the newly available ''Quickbird'' satellite …
Date: May 14, 2004
Creator: Pickles, W & Cover, W
System: The UNT Digital Library
Steam Digest: Volume IV (open access)

Steam Digest: Volume IV

This edition of the Steam Digest is a compendium of 2003 articles on the technical and financial benefits of steam efficiency, presented by the stakeholders of the U.S. Department of Energy's BestPractices Steam effort.
Date: July 1, 2004
Creator: unknown
System: The UNT Digital Library
Improving Process Heating System Performance: A Sourcebook for Industry (open access)

Improving Process Heating System Performance: A Sourcebook for Industry

A sourcebook designed to provide process heating system users with a reference outlining opportunities to improve system performance and optimize energy efficiency in industrial energy systems.
Date: September 1, 2004
Creator: unknown
System: The UNT Digital Library
14th Workshop on Crystalline Silicon Solar Cells & Modules: Materials and Processes; Extended Abstracts and Papers (open access)

14th Workshop on Crystalline Silicon Solar Cells & Modules: Materials and Processes; Extended Abstracts and Papers

The 14th Workshop will provide a forum for an informal exchange of technical and scientific information between international researchers in the photovoltaic and relevant non-photovoltaic fields. It will offer an excellent opportunity for researchers in private industry and at universities to prioritize mutual needs for future collaborative research. The workshop is intended to address the fundamental properties of PV silicon, new solar cell designs, advanced solar cell processing techniques, and cell-related module issues. A combination of oral presentations by invited speakers, poster sessions, and discussion sessions will review recent advances in crystal growth, new cell designs, new processes and process characterization techniques, cell fabrication approaches suitable for future manufacturing demands, and solar cell encapsulation. This year's theme, ''Crystalline Si Solar Cells: Leapfrogging the Barriers,'' reflects the continued success of crystalline Si PV in overcoming technological barriers to improve solar cell performance and lower the cost of Si PV. The workshop will consist of presentations by invited speakers, followed by discussion sessions. In addition, there will be two poster sessions presenting the latest research and development results. Some presentations will address recent technologies in the microelectronics field that may have a direct bearing on PV. The sessions will include: Advances in …
Date: August 1, 2004
Creator: Sopori, B. L.
System: The UNT Digital Library
CFD Simulation of Airflow in Ventilated Wall System Report #9 (open access)

CFD Simulation of Airflow in Ventilated Wall System Report #9

The objective of this report was to examine air movements in vinyl and brick ventilation cavities in detail, using a state of the art CFD commercial modeling tool. The CFD activity was planned to proceed the other activities in order to develop insight on the important magnitudes of scales occurring during ventilation air flow. This information generated by the CFD model was to be used to modify (if necessary) and to validate the air flow dynamics already imbedded in the hygrothermal model for the computer-based air flow simulation procedures. A comprehensive program of advanced, state-of-the-art hygrothermal modeling was then envisaged mainly to extend the knowledge to other wall systems and at least six representative climatic areas. These data were then to be used to provide the basis for the development of design guidelines. CFD results provided timely and much needed answers to many of the concerns and questions related to ventilation flows due to thermal buoyancy and wind-driven flow scenarios. The relative strength between these two mechanisms. Simple correlations were developed and are presented in the report providing the overall pressure drop, and flow through various cavities under different exterior solar and temperature scenarios. Brick Rainscreen Wall: It was initially …
Date: January 1, 2004
Creator: Stovall, Therese K & Karagiozis, Achilles N
System: The UNT Digital Library
Procurement of Architectural and Engineering Services for Sustainable Buildings: A Guide for Federal Project Managers (open access)

Procurement of Architectural and Engineering Services for Sustainable Buildings: A Guide for Federal Project Managers

This guide was prepared to be a resource for federal construction project managers and others who want to integrate the principles of sustainable design into the procurement of professional building design and consulting services. To economize on energy costs and improve the safety, comfort, and health of building occupants, building design teams can incorporate daylighting, energy efficiency, renewable energy, and passive solar design into all projects in which these elements are technically and economically feasible. The information presented here will help project leaders begin the process and manage the inclusion of sustainable design in the procurement process. The section on establishing selection criteria contains key elements to consider before selecting an architectural and engineering (A/E) firm. The section on preparing the statement of work discusses the broad spectrum of sustainable design services that an A/E firm can provide. Several helpful checklists are included.
Date: June 1, 2004
Creator: unknown
System: The UNT Digital Library
Evaluation of the Compressed Air Challenge(R) Training Program (Executive Summary) (open access)

Evaluation of the Compressed Air Challenge(R) Training Program (Executive Summary)

The final report of the evaluation of the Compressed Air Challenge (CAC) Training Program. The training program is designed to provide plant personnel and compressed air system vendors with knowledge and tools required to effect improvements to the energy efficiency and overall performance of plant compressed air systems. As of May 2001, 3,029 individuals had attended the CAC Fundamentals of Compressed Air Training Systems and 925 individuals had attended ''Advanced Management of Compressed Air Systems''. These individuals represented 1,400-1,500 separate business establishments. The evaluation is based on three main research tasks: analysis of the CAC registration database, interviews with 100 end-user personnel who attended the CAC training, and interviews with 100 compressed air system vendors and consulting engineers who attended the training sessions.
Date: March 1, 2004
Creator: unknown
System: The UNT Digital Library