Publications

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Erbium dihydride Er(H,D,T){sub 2} is a fluorite structure rare-earth dihydride useful for the storage of hydrogen isotopes in the solid state. However, thermodynamic predictions indicate that erbium oxide formation will proceed readily during processing, which may detrimentally contaminate Er(H,D,T){sub 2} films. In this work, transmission electron microscopy (TEM) techniques including energy-dispersive x-ray spectroscopy, energy-filtered TEM, selected area electron diffraction, and high-resolution TEM are used to examine the manifestation of oxygen contamination in ErD{sub 2} thin films. An oxide layer {approx}30-130 nm thick was found on top of the underlying ErD{sub 2} film, and showed a cube-on-cube epitaxial orientation to the underlying ErD{sub 2}. Electron diffraction confirmed the oxide layer to be Er{sub 2}O{sub 3}. While the majority of the film was observed to have the expected fluorite structure for ErD{sub 2}, secondary diffraction spots suggested the possibility of either nanoscale oxide inclusions or hydrogen ordering. In situ heating experiments combined with electron diffraction ruled out the possibility of hydrogen ordering, so epitaxial oxide nanoinclusions within the ErD{sub 2} matrix are hypothesized. TEM techniques were applied to examine this oxide nanoinclusion hypothesis.

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The objective of the experimental effort is to provide a model particle system that will enable modeling of the macroscopic rheology from the interfacial and environmental structure of the particles and solvent or melt as functions of applied shear and volume fraction of the solid particles. This chapter describes the choice of the model particle system, methods for synthesis and characterization, and results from characterization of colloidal dispersion, particle film formation, and the shear and oscillatory rheology in the system. Surface characterization of the grafted PDMS interface, dispersion characterization of the colloids, and rheological characterization of the dispersions as a function of volume fraction were conducted.

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In the title compound, C{sub 27}H{sub 17}N{sub 3}O{sub 4}, the azo group displays a trans conformation and the dihedral angles between the central benzene ring and the pendant anthracene and nitrobenzene rings are 82.94 (7) and 7.30 (9){sup o}, respectively. In the crystal structure, weak C-H...O hydrogen bonds, likely associated with a dipole moment present on the molecule, help to consolidate the packing.

This one-year exploratory LDRD aims to provide fundamental understanding of the mechanism of CO₂ scrubbing platforms that will reduce green house gas emission and mitigate the effect of climate change. The project builds on the team member's expertise developed in previous LDRD projects to study the capture or preferential retention of CO₂ in nanoporous membranes and on metal oxide surfaces. We apply Density Functional Theory and ab initio molecular dynamics techniques to model the binding of CO₂ on MgO and CaO (100) surfaces and inside water-filled, amine group functionalized silica nanopores. The results elucidate the mechanisms of CO₂ trapping and clarify some confusion in the literature. Our work identifies key future calculations that will have the greatest impact on CO₂ capture technologies, and provides guidance to science-based design of platforms that can separate the green house gas CO₂ from power plant exhaust or even from the atmosphere. Experimentally, we modify commercial MFI zeolite membranes and find that they preferentially transmit H₂ over CO₂ by a factor of 34. Since zeolite has potential catalytic capability to crack hydrocarbons into CO₂ and H₂, this finding paves the way for zeolite membranes that can convert biofuel into H₂ and separate the products all in one step.

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The primary function of the Gamma Detector Response and Analysis Software (GADRAS) is the solution of inverse radiation transport problems, by which the configuration of an unknown radiation source is inferred from one or more measured radiation signatures. GADRAS was originally developed for the analysis of gamma spectrometry measurements. During fiscal years 2007 and 2008, GADRAS was augmented to implement the simultaneous analysis of neutron multiplicity measurements. This report describes the radiation transport methods developed to implement this new capability. This work was performed at the direction of the National Nuclear Security Administration's Office of Nonproliferation Research and Development. It was executed as an element of the Proliferation Detection Program's Simulation, Algorithm, and Modeling element.

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We report on the work done in the late-start LDRD Using Emulation and Simulation to Understand the Large-Scale Behavior of the Internet. We describe the creation of a research platform that emulates many thousands of machines to be used for the study of large-scale inter-net behavior. We describe a proof-of-concept simple attack we performed in this environment. We describe the successful capture of a Storm bot and, from the study of the bot and further literature search, establish large-scale aspects we seek to understand via emulation of Storm on our research platform in possible follow-on work. Finally, we discuss possible future work.