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Sample records for hogan-brun uldis ozolins

  1. Deaf Education Policy as Language Policy: A Comparative Analysis of Sweden and the United States

    ERIC Educational Resources Information Center

    Hult, Francis M.; Compton, Sarah E.

    2012-01-01

    The role of languages is a central issue in deaf education. The function of sign languages in education and deaf students' opportunities to develop linguistic abilities in both sign languages and the dominant language(s) of a society are key considerations (Hogan-Brun 2009; Reagan 2010, 53; Swanwick 2010a). Accordingly, what Kaplan and Baldauf…

  2. Deaf Education Policy as Language Policy: A Comparative Analysis of Sweden and the United States

    ERIC Educational Resources Information Center

    Hult, Francis M.; Compton, Sarah E.

    2012-01-01

    The role of languages is a central issue in deaf education. The function of sign languages in education and deaf students' opportunities to develop linguistic abilities in both sign languages and the dominant language(s) of a society are key considerations (Hogan-Brun 2009; Reagan 2010, 53; Swanwick 2010a). Accordingly, what Kaplan and Baldauf…

  3. Computational Discovery of Novel Hydrogen Storage Materials and Reactions

    NASA Astrophysics Data System (ADS)

    Wolverton, Christopher

    2009-03-01

    Practical hydrogen storage for mobile applications requires materials that exhibit high hydrogen densities, low decomposition temperatures, and fast kinetics for absorption and desorption. Unfortunately, no reversible materials are currently known that possess all of these attributes. Here we present an overview of our recent efforts aimed at developing a first-principles computational approach to the discovery of novel hydrogen storage materials. We have developed computational tools which enable accurate prediction of decomposition thermodynamics, crystal structures for unknown hydrides, and thermodynamically preferred decomposition pathways. We present examples that illustrate each of these three capabilities. Specifically, we focus on recent work on crystal structure and dehydriding reactions of borohydride materials, such as Mg(BH4)2, MgB12H12, and mixtures of complex hydrides such as the ternary LiBH4/LiNH2/MgH2 system.References:[0pt] (1) V. Ozolins, E. H. Majzoub, and C. Wolverton, ``First-Principles Prediction of a Ground State Crystal Structure of Magnesium Borohydride'', Phys. Rev. Lett. 100, 135501 (2008).(2) C. Wolverton, D. J. Siegel, A. R. Akbarzadeh, and V. Ozolins, ``Discovery of Novel Hydrogen Storage Materials: An Atomic Scale Computational Approach'', J. Phys. Condens. Matt. 20, 064228 (2008).(3) J. Yang, et al., ``A Self-Catalyzing Hydrogen Storage Material'' Angew. Chem. Int. Ed., 47, 882 (2008).(4) A. R. Akbarzadeh, V. Ozolins, and C. Wolverton, ``First-Principles Determination of Multicomponent Hydride Phase Diagrams: Application to the Li-Mg-N-H System'', Advanced Materials 19, 3233 (2007).(5) D. J. Siegel, C. Wolverton, and V. Ozolins, ``Thermodynamic Guidelines for the Prediction of Hydrogen Storage Reactions and their Application to Destabilized Hydride Mixtures'', Phys. Rev. B 76, 134102 (2007).

  4. RETRACTED: Crystal structures of XnB12H12 (X = Li, K, Ca) and hydrogen storage property of Na-(Li, K, Ca)-B-H system from first principles calculation

    NASA Astrophysics Data System (ADS)

    YaJuan, Guo; JianFeng, Jia; XiaoHua, Wang; Ying, Ren; HaiShun, Wu

    2013-02-01

    This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy).This article has been retracted at the request of the Editor-in-Chief.The Authors have plagiarized part of a paper that had already appeared in: V. Ozolins, E. H. Majzoub and C. Wolverton, First-Principles Prediction of Thermodynamically Reversible Hydrogen Storage Reactions in the Li-Mg-Ca-B-H System, J. Am. Chem. Soc. 131 (2009) 230-237; DOI:http://dx.doi.org/10.1021/ja8066429.One of the conditions of submission of a paper for publication is that authors declare explicitly that their work is original and has not appeared in a publication elsewhere. Re-use of any data should be appropriately cited. As such this article represents a severe abuse of the scientific publishing system. The scientific community takes a very strong view on this matter and apologies are offered to readers of the journal that this was not detected during the submission process.

  5. Finding Symmetry-adapted Wannier Functions from L1 Sparse Optimization

    NASA Astrophysics Data System (ADS)

    Chen, Jiatong; Yin, Ke; Xia, Yi; Ozolins, Vidvuds; Osher, Stanley; Caflisch, Russel

    2015-03-01

    Wannier functions have applications in numerous fields of condensed matter physics, from polarization and orbital magnetization to topological insulators and linear-scaling methods for electronic structure calculations. We present a technique to calculate symmetry-adapted Wannier functions that are strictly localized within a finite region based on the framework of compressed Wannier modes [V. Ozolins, R. Lai, R. Caflisch, S. Osher. Proc. Natl. Acad. Sci. USA 2014 111 (5) 1691-1696]. Our method does not require a prior computation of the band structure, but directly minimizes a functional that is the sum of the total energy and an L1 regularization term 1/μ ∫ | Ψ | dr , which drives strict localization. One parameter μ controls the trade-off between the localization and the energy accuracy. Here we show how symmetry constraints can be incorporated in this formalism, leading to Wannier functions that form irreducible representations of the crystal group. Since only k points from the irreducible wedge of the Brillouin zone need to be considered, the computational effort is similar to that required for conventional band structure calculations.

  6. Transition metal based borohydrides for hydrogen storage

    NASA Astrophysics Data System (ADS)

    Jayanthi, Chakram; Liu, Jianjun; Wei, Suhuai; Zhao, Yufeng

    2010-03-01

    Using ab-initio studies based on the density-functional theory, we have calculated binding energies per hydrogen molecule for decomposition reactions of transition metal borohydrides MHxB12H12 to MB12 structures, where M corresponds to Sc, Ti, or V. Depending on the valence of the transition metal, x can be 1, 2, or 3. Crystal structures considered for MB12 included both hypothetical and those found in the international crystallographic structural database. On the other hand, the crystal structure considered for MHxB12H12 belongs to C2/c (space group 15) structure as reported in a previous study [V. Ozolins et al. JACS, 131, 230 (2009)]. Among the structures investigated, Titanium-based metal borohydride structure has the lowest binding energy per hydrogen molecule relative to the cubic TiB12 structure (˜0.37 eV/H2). Our finding should be contrasted with the binding energy/H2 for simple metal based borohydrides (e.g., CaB12H12 ), which has a value of ˜ 1.5 eV/H2, suggesting that transition metals play a significant role in lowering the H2 binding energy in borohydrides.

  7. Discovery of Novel Complex Metal Hydrides for Hydrogen Storage through Molecular Modeling and Combinatorial Methods

    SciTech Connect

    Lesch, David A; Adriaan Sachtler, J.W. J.; Low, John J; Jensen, Craig M; Ozolins, Vidvuds; Siegel, Don; Harmon, Laurel

    2011-02-14

    UOP LLC, a Honeywell Company, Ford Motor Company, and Striatus, Inc., collaborated with Professor Craig Jensen of the University of Hawaii and Professor Vidvuds Ozolins of University of California, Los Angeles on a multi-year cost-shared program to discover novel complex metal hydrides for hydrogen storage. This innovative program combined sophisticated molecular modeling with high throughput combinatorial experiments to maximize the probability of identifying commercially relevant, economical hydrogen storage materials with broad application. A set of tools was developed to pursue the medium throughput (MT) and high throughput (HT) combinatorial exploratory investigation of novel complex metal hydrides for hydrogen storage. The assay programs consisted of monitoring hydrogen evolution as a function of temperature. This project also incorporated theoretical methods to help select candidate materials families for testing. The Virtual High Throughput Screening served as a virtual laboratory, calculating structures and their properties. First Principles calculations were applied to various systems to examine hydrogen storage reaction pathways and the associated thermodynamics. The experimental program began with the validation of the MT assay tool with NaAlH4/0.02 mole Ti, the state of the art hydrogen storage system given by decomposition of sodium alanate to sodium hydride, aluminum metal, and hydrogen. Once certified, a combinatorial 21-point study of the NaAlH4 LiAlH4Mg(AlH4)2 phase diagram was investigated with the MT assay. Stability proved to be a problem as many of the materials decomposed during synthesis, altering the expected assay results. This resulted in repeating the entire experiment with a mild milling approach, which only temporarily increased capacity. NaAlH4 was the best performer in both studies and no new mixed alanates were observed, a result consistent with the VHTS. Powder XRD suggested that the reverse reaction, the regeneration of the