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Towards Understanding the Mechanism of PETN Coarsening (open access)

Towards Understanding the Mechanism of PETN Coarsening

The long-term goal is to determine the mechanism of PETN crystallization and coarsening at the solid-vapor interface and to quantify the thermodynamic and kinetic parameters that control those processes. We achieve this goal by investigating the surface evolution of synthetic PETN single crystals using in situ atomic force microscopy (AFM) at various temperatures.
Date: March 23, 2005
Creator: Qiu, R.; Overturf, G.; Gee, R.; Burnham, A.; Weeks, B. & De Yoreo, J.
System: The UNT Digital Library
2004 Structural, Function and Evolutionary Genomics (open access)

2004 Structural, Function and Evolutionary Genomics

This Gordon conference will cover the areas of structural, functional and evolutionary genomics. It will take a systematic approach to genomics, examining the evolution of proteins, protein functional sites, protein-protein interactions, regulatory networks, and metabolic networks. Emphasis will be placed on what we can learn from comparative genomics and entire genomes and proteomes.
Date: March 23, 2005
Creator: Gray, Douglas L. Brutlag Nancy Ryan
System: The UNT Digital Library
2004 Reversible Associations in Structure & Molecular Biology (open access)

2004 Reversible Associations in Structure & Molecular Biology

The Gordon Research Conference (GRC) on 2004 Gordon Research Conference on Reversible Associations in Structure & Molecular Biology was held at Four Points Sheraton, CA, 1/25-30/2004. The Conference was well attended with 82 participants (attendees list attached). The attendees represented the spectrum of endeavor in this field coming from academia, industry, and government laboratories, both U.S. and foreign scientists, senior researchers, young investigators, and students.
Date: March 23, 2005
Creator: Gray, Edward Eisenstein Nancy Ryan
System: The UNT Digital Library
Pore Fluid Effects on Shear Modulus in a Model of Heterogeneous Rocks, Reservoirs, and Granular Media (open access)

Pore Fluid Effects on Shear Modulus in a Model of Heterogeneous Rocks, Reservoirs, and Granular Media

To provide quantitative measures of the importance of fluid effects on shear waves in heterogeneous reservoirs, a model material called a ''random polycrystal of porous laminates'' is introduced. This model poroelastic material has constituent grains that are layered (or laminated), and each layer is an isotropic, microhomogeneous porous medium. All grains are composed of exactly the same porous constituents, and have the same relative volume fractions. The order of lamination is not important because the up-scaling method used to determine the transversely isotropic (hexagonal) properties of the grains is Backus averaging, which--for quasi-static or long-wavelength behavior--depends only on the volume fractions and layer properties. Grains are then jumbled together totally at random, filling all space, and producing an overall isotropic poroelastic medium. The poroelastic behavior of this medium is then analyzed using the Peselnick-Meister-Watt bounds (of Hashin-Shtrikman type). We study the dependence of the shear modulus on pore fluid properties and determine the range of behavior to be expected. In particular we compare and contrast these results to those anticipated from Gassmann's fluid substitution formulas, and to the predictions of Mavko and Jizba for very low porosity rocks with flat cracks. This approach also permits the study of arbitrary numbers …
Date: March 23, 2005
Creator: Berger, E. L.
System: The UNT Digital Library
CP: AN INVESTIGATION OF COEFFICIENT OF THERMAL EXPANSION, DECOMPOSITION KINETICS, AND REACTION TO VARIOUS STIMULI (open access)

CP: AN INVESTIGATION OF COEFFICIENT OF THERMAL EXPANSION, DECOMPOSITION KINETICS, AND REACTION TO VARIOUS STIMULI

The properties of pentaamine (5-cyano-2H-tetrazolato-N2) cobalt (III) perchlorate (CP), which was first synthesized in 1968, continues to be of interest for predicting behavior in handling, shipping, aging, and thermal cook-off situations. We report coefficient of thermal expansion (CTE) values over four specific temperature ranges, decomposition kinetics using linear heating rates, and the reaction to three different types of stimuli: impact, spark, and friction. The CTE was measured using a Thermal Mechanical Analyzer (TMA) for samples that were uniaxially compressed at 10,000 psi and analyzed over a dynamic temperature range of -20 C to 70 C. Using differential scanning calorimetry, DSC, CP was decomposed at linear heating rates of 1, 3, and 7 C/min and the kinetic triplet calculated using the LLNL code Kinetics05. Values are also reported for spark, friction, and impact sensitivity.
Date: March 23, 2005
Creator: Weese, R. K.; Burnham, A. K. & Fontes, A. T.
System: The UNT Digital Library
An Overview of the Target Fabrication Operations at Lawrence Livermore National Laboratory (open access)

An Overview of the Target Fabrication Operations at Lawrence Livermore National Laboratory

The Target Engineering team at Lawrence Livermore National Laboratory (LLNL) builds precision laser targets for the National Ignition Facility (NIF) and the Omega Laser in Rochester, NY, and other experimental facilities. The physics requirements demand precision in these targets, which creates a constant need for innovative manufacturing processes. As experimental diagnostics improve, there is greater demand for precision in fabrication, assembly, metrology, and documentation of as-built targets. The team specializes in meso-scale fabrication with core competencies in diamond turning, assembly, and metrology. Figure 1 shows a typical diamond turning center. The team builds over 200 laser targets per year in batches of five to fifteen targets. Thus, all are small-lot custom builds, and most are novel designs requiring engineering and process development. Component materials are metals, polymers and low density aerogel foams. Custom fixturing is used to locate parts on the Diamond Turning Machines (DTM) and assembly stations. This ensures parts can be repeatably located during manufacturing operations. Most target builds involve a series of fabricating one surface with features and then relocating the components on another fixture to finish the opposite side of the component. These components are then assembled to complete multiple-component targets. These targets are typically built …
Date: March 23, 2005
Creator: Hibbard, R L & Bono, M J
System: The UNT Digital Library
Surrogate Nuclear Reactions - An Indirect Method for Determining Reaction Cross Sections (open access)

Surrogate Nuclear Reactions - An Indirect Method for Determining Reaction Cross Sections

An indirect method for determining cross sections of reactions proceeding through a compound nucleus is presented. Some applications of the Surrogate nuclear reaction approach are considered and challenges that need to be addressed are outlined.
Date: March 23, 2005
Creator: Escher, J; Ahle, L; Bernstein, L; Burke, J; Church, J A; Dietrich, F et al.
System: The UNT Digital Library