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IMMS Papers

2011 Papers
2010 Papers
2009 Papers
2008 Papers

    2011 Papers

  • Joan Shea

  • Directing Zeolite Structures into Hierarchically Nanoporous Architectures
    Rob Messinger

    Kyungsu Na, Changbum Jo, Jeongnam Kim, Kanghee Cho, Jinhwan Jung, Yongbeom Seo, Bradley F. Chmelka, and Ryong Ryoo

  • DNA Dynamics is Likely to be a Factor in the Genomic Nucleotide Repeats Expansions Related to Disease
    Boian Alexandrov, Kim Rasmussen
  • DNA Dynamics Is Likely to Be a Factor in the Genomic Nucleotide Repeats Expansions Related to Diseases
    Kim Rasmussen, Boian Alexandrov

    V.I. Valtchinov, V. Gelev, Y. Dagon J. Bock, I.S. Kohane,  A. Usheva

  • Entropy–Driven Conformations Controlling DNA Functions
    Kim Rasmussen, Boian Alexandrov

    A. Usheva

  • Molecular Optimization of Multiply-Functionalized Mesoporous Films with Ion Conduction Propoerties
    Brad Chmelka, Donghun Kim

    Also:  George L. Athens, Jan D. Epping, Sylvian Cadars, Yair Ein-Eli

  • Molecular Origins of Macroscopic Mechanical Properties in Elastomeric Orgtanosiloxane Foams
    Brad Chmelka, Fred Milstein, Rob Messinger, Trevor Marks

    Also Seth Gleiman

  • Polymer-Based Materials and Composites-Synthesis, Assembly, Properties and Applications
    Debra Wrobleski

    Conference Proceedings

  • Polymorph specific RMSD local order parameters for molecular crystals and nuclei: a-, B-, and y-glycine
    Nathan Duff
  • Thermal Fluctuations in Shape, Thickness and Molecular Orientation in Lipid Bilayers
    Paul Welch

    Max C. Watson, Evgeni S. Penev, and Frank L. H. Brown

    2010 Papers

  • Atomic displacements in the charge ice pyrochlore Bi2Ti2060 studied by neutron total scattering
    Daniel Shoemaker
  • Chemical fixed p-n heterojunctions for polymer electronics by means of covalent B-F bond formation
    Corey Hoven

    UCSB Author:  Bazan, GC

  • Chemically fixed p-n heterojunctions for polymer electronics by means of covalent B-F bond formation
    Corey Hoven

    Co-author:  Guillermo Bazanl.  The paper is all available through http://dx.doi.org

  • Improved Performance of Polymer Bulk Heterojunction Solar Cells Through the Reduction of Phase Separation via Solvent Additives
    Corey Hoven

    UCSB Author:  Nguyen, Thuc-Quyen

  • Real space investigation of structural changes at the metal-insulator transition in VO2
    Daniel Shoemaker
  • Suppression of Electro-Osmotic Flow by Surface Roughness
    Todd Squires, Rob Messinger
  • The Janus Character of Heterogeneous Dendritic Nanoparticles
    Craig Hawker, Jerred Chute, Kim Rasmussen, Paul Welch

    Need specific date of publication and volume, etc.

  • The Janus Character of Heterogeneous Dendritic Nanoparticles
    Craig Hawker, Jerred Chute, Kim Rasmussen, Paul Welch
  • The Los Alamos Neutron Science Center neutron rheometer in the cone and plate geometry to examine tethered polymers/polymer melt interfaces via neutron reflectivity
    Christopher Hammetter, Rex Hjelm
  • Total-scattering descriptions of local and cooperative distortions in the oxide spinel Mgl-xCuxCr204 with dilute Jahn-Teller ions
    Ram Seshadri, Daniel Shoemaker

    2009 Papers

  • Intrinsic exchange bias in ZnxMn3-xO4 solid solutions
    Ram Seshadri, Daniel Shoemaker, Thomas Proffen

    Bulk specimens of the hetaerolite solid solution ZnxMn3-xO4, with x = 0, 0.25, 0.5, 0.75, and 1 have been prepared as homogeneous, phase-pure polycrystalline samples as ascertained by neutron diffraction measurements. Samples with x = 0.25, 0.5, and 0.75 exhibit shifted magnetic hysteresis loops at low temperature, characteristic of exchange bias typically seen in magnetic composites. We propose that the unusual magnetic behavior arises as a result of a nanoscale mixture of ferrimagnetic and antiferromagnetic regions that are distinct but lack long-range order. While some glassy behavior is seen in AC magnetic measurements, its magnitude is not sufficient to account for the observed dramatic exchange bias. Furthermore, isothermal and thermoremanent magnetization measurements distinguish this material from a pure spin glass. The title system offers insights into the alloying of a ferrimagnet Mn3O4 with an antiferromagnet ZnMn2O4 wherein distinct magnetic clusters grow and percolate to produce a smooth transition between competing orders.

  • Molecular Dynamics of the Electric Double Layer
    Brian Giera

    2009 Student Symposium

  • Unraveling Atomic Positions in an Oxide Spinel with Two Jahn−Teller Ions: Local Structure Investigation of CuMn2O4
    Ram Seshadri, Daniel Shoemaker

    At first sight, the quenched tetragonal spinel CuMn2O4 can be formulated with Cu2+ and Mn3+, implying that the tetrahedral site is Jahn−Teller (JT)-active Cu2+and the octahedral site is JT-active Mn3+. High-resolution, high-momentum-transfer neutron scattering analysis suggests that the sample has 30% inversion: Mn on the tetrahedral Cu site with compensating Cu on the octahedral site. Reverse Monte Carlo (RMC) analysis of the pair distribution function allows details of metal−oxygen connectivity to be probed in a manner that is significantly on the local rather than the average scale. Bond valence analysis of the RMC supercell reveals that both JT ions disproportionate to higher and lower valence states as a means of avoiding their JT tendency, particularly on the tetrahedral site. The occurrence of Cu3+ in particular is suggested for the first time and is supported by X-ray photoelectron spectroscopy data. The bimodal distribution of O−Cu−O bond angles at the tetrahedral site (distinct from what is seen for O−Mn−O bond angles) further reveals a hidden distinction between sites previously considered to be equivalent. Application of total scattering techniques originally developed for highly disordered materials permits the examination of nanoscale crystalline structure with elemental specificity that is not available in traditional reciprocal-space analysis.

  • VISTAS, Experimental Physical Sciences
    Ed Kober

    Los Alamos Materials Strategy

    2008 Papers

  • Making it stick: convection, reaction and diffusion in surface-based biosensors
    Todd Squires, Rob Messinger

    The past decade has seen researchers develop and apply novel technologies for biomolecular detection, at times approaching hard limits imposed by physics and chemistry. In nearly all sensors, the transport of target molecules to the sensor can play as critical a role as the chemical reaction itself in governing binding kinetics, and ultimately performance. Yet rarely does an analysis of the interplay between diffusion, convection and reaction motivate experimental design or interpretation. Here we develop a physically intuitive and practical understanding of analyte transport for researchers who develop and employ biosensors based on surface capture. We explore the qualitatively distinct behaviors that result, develop rules of thumb to quickly determine how a given system will behave, and derive order-of-magnitude estimates for fundamental quantities of interest, such as fluxes, collection rates and equilibration times. We pay particular attention to collection limits for micro- and nanoscale sensors, and highlight unexplained discrepancies between reported values and theoretical limits

  • Making it Stick: convection, reaction and diffusion in surface-based biosensors
    Todd Squires, Rob Messinger
  • Ordering and Reverse Ordering Mechanisms of Triblock Copolymers in the Presence of Solvent
    Kim Rasmussen, Ed Kober

    Self-consistent field theory is used to study the self-assembly of a triblock copolymer melt. Two different external factors (temperature and solvent) are shown to affect the self-assembly. Either one or two-step self-assembly can be found as a function of temperature in the case of a neat triblock melt, or as a function of increasing solvent content (for non-selective solvents) in the case of a triblock-solvent mixture. For selective solvents, it is shown that increasing the solvent content leads to more complicated self-assembly mechanisms, including a reversed transition where order is found to increase instead of decreasing as expected, and re-entrant behavior where order is found to increase at first, and then decrease to a previous state of disorder.

Theses and Dissertations

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