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April 2015
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1

  1. No events scheduled

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  1. Center for Functional Nanomaterials Seminar

    9:45 am, CFN Bldg. 735 - Second Floor Conference Room B

    Hosted by: Kevin Yager

    Recovery of three-dimensional structure from single particle X-ray scattering of completely randomly oriented diffraction patterns as predicted few decades back has been real due to advent of the new emerging XFEL (X-ray free electron laser) technology. Some of the best-known structure determination of helical objects such as helical viruses or deoxyribonucleic acid has been done by fiber diffraction. Layer line intensities of fiber diffraction pattern as expressed by cylindrical harmonics can be transformed into equivalent spherical harmonic expansion leaving the clue behind that structure of helical objects may be recovered from single particle scattering of randomly oriented helical molecules thus avoiding the tedious challenge of single axis alignment. In this work we have solved the structure of TMV (tobacco mosaic virus) helices from a set of randomly oriented simulated diffraction patterns exploiting symmetry and internal constraint of the diffraction volume thus proving the above claim on step ahead. As the world's first XFEL is in operation starting from June 2009 at SLAC National Lab at Stanford, the very first few experiments being conducted on larger objects such as viruses. We have analyzed a set of experimental diffraction patterns of chlorella virus deposited on cxidb.org and recovered a quadratic coefficients of Fourier shell correlation whose angular momentum selection rule proves that the collected data is primarily from an icosahedral object.

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  1. Center for Functional Nanomaterials Seminar

    11 am, CFN Bldg. 735 - First Floor Conference Room A

    Hosted by: Oleg Gang

    One of the main goals of nanotechnology is developing methods for creation of designed nano-scaled systems with ability to control their structures, transformations and dynamic processes. Such full control over the material design will permit achieving the desired functional properties. Approaches based on DNA-driven assembly of nanosystems were recently demonstrated as a powerful route for regulated self-assembly at nanoscale. Metal nanoparticles or quantum dots, functionalized with oligonucleotides are envisioned in this approach to be precisely directed in targeted structures, in bulk, at surfaces or within a cluster. The Watson-Crick recognition between DNA grafted on particle surface allows for programming interparticle interactions with extreme richness and thermodynamical tunability. We extended DNA-assembly methodology for fabrication of dynamically responsive nanoclusters and nanocrystals using a linking particles 'i-motif', a DNA sequence that responds to pH stimulation. DNA double strands were also applied as an interparticle distance controller to self-assemble a series of clusters with core-shell architecture. The core, gold nanoparticle (AuNP) was surrounded by the shell of DNA-attached colloidal quantum dots (QD), forming AuNP-DNA-QD clusters with tunable optical (photoluminescence) responses, which mimics the architecture of light harvesting complex. A novel strategy for assembling 3D nanoparticle clusters was demonstrated: designing a molecular frame with encoded vertices for particles placement. Using a DNA origami octahedron as such frame, we positioned specific particles types at the octahedron vertices, which permitted a fabrication of clusters with different symmetries and particles composition. We applied the combination of cryo-EM technique and single particle method to uncover the structure of the DNA frame and to reveal that nanoparticles are spatially coordinated in the prescribed manner. We also proposed a ne

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  1. Center for Functional Nanomaterials Colloquium

    11 am, Bldg 735, CFN 2nd Floor Seminar Room

    Hosted by: Eric Stach

    Connecting the underlying chemical processes with the growth and emergent form remains unsurmountable problem in life sciences [1]. In materials research, the current outlook is more optimistic: establishing such connection, from the basic interatomic forces to growing nanostructure shape and properties becomes a real possibility. We will discuss several important examples, focusing on two recent results. First one concerns the nanotubes, where it took two decades to derive a kinetic formula [2] R ~ sin x (growth rate R, helical angle x). Further analysis of the subtle balance between the kinetic and thermodynamic views reveals sharply peaked abundance distribution A ~ x exp (-x) [3]. This explains the puzzling (n, n-1) types observed in many experiments. In the second example, a combination of DFT and Monte Carlo models explains the low symmetry shapes of graphene on substrates. In equilibrium, edge energy variation dE manifests in slightly distorted hexagons. In growth, it enters as ~exp(-dE/kT), amplifying the symmetry breaking to triangle, ribbon, rhomb [4]. Third example concerns 2D materials of more complex chemistry, h-BN and MX2 among them, and how their defects, dislocations and grain boundaries, predicted from the first principles, find remarkable experimental confirmations [5]. [1] On Growth and Form, by D'Arcy W. Thompson (Cambridge U, 1917). [2] F. Ding et al. PNAS 106, 2506 (2009); R. Rao et al. Nature Mater. 11, 213 (2012). [3] V. Artyukhov - E. Penev et al. Nature Comm. 5, 489 (2014). [4] Y. Liu et al. PRL 105, 235502 (2010); V. Artyukhov et al. PNAS 109, 15136 (2012); Y. Hao et al. Science, 342, 720 (2013); V. Artyukhov et al. PRL 114, 115502 (2015). [5] X. Zou, et al. Nano Lett., 13, 253 (2013); S. Najmaei et al. Nature Materials, 12, 754 (2013); A. Aziz et al. Nature Comm., 5, 4867 (2014). *** Boris I. Yakobson is an expert in theory and computational modeling of materials na

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  1. Center for Functional Nanomaterials Seminar

    10 am, CFN Bldg. 735 - Second Floor Conference Room B

    Hosted by: Kevin Yager

    Xray Photon Correlation Spectroscopy (XPCS) allows the measurement of dynamics on small length scales through the fluctuations of a far field diffraction pattern produced by micron sized partially coherent xray beams. I will describe the analysis of systems containing directed motion through two main topics. The first will be the measurement of velocity fields using a heterodyne technique. The second will be the use of a spatial extension to XPCS to probe flow gradients or strain fields. The deformation of a rubber polymer with Angstrom resolution over the course of a few seconds is measured. The experimental setup, data analysis and initial results will be presented, along with some discussion of the limitations and capabilities.

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  1. APR

    30

    Thursday

    Center for Functional Nanomaterials Seminar

    11 am, Bldg 735, Conference Room A

    Thursday, April 30, 2015, 11:00 am

    Hosted by: James Dickerson

    The theme of this presentation is the use of microstructural control to extend the favorable attributes of "Nano", and minimize the undesirable ones, in relation to lithium ion batteries (LIBs), sodium ion batteries (SIBs) and electrochemical supercapacitors. In this talk I will cover several examples where proper microstructural design provides substantial improvements: A) The use of nanoscale coatings to more than double the cycling capacity retention and achieve near 100% coulombic efficiency of Si nanowire and nanotube LIB anodes; B) Fabricating improved materials for Na ion battery anodes through tailored metal alloys and pseudographitic carbons; C) Converting a common livestock biowaste, in the form of chicken eggshell membranes and inedible egg whites, to electrodes with some of the highest specific capacitances and Li storage capacities reported in literature for any carbon; D) Creating carbons with electrochemical performance on par or even better than graphene for a range of energy storage devices, from hemp fibers, banana peels and peat moss. In all cases I will detail the key synthesis ��" microstructure features that transform the performance of these materials from mundane to remarkable. Recent media coverage: http://www.altmetric.com/details.php?citation_id=1462145&src=bookmarklet

  1. APR

    30

    Thursday

    Center for Functional Nanomaterials Seminar

    "David Mitlin: Design of Electrode Microstructures that Bridge Supercapacitors and Batteries"

    Presented by David Mitlin, Clarkson University, Chemical & Biomolecular Engineering and Mechanical Engineering

    11 am, Bldg 735, Conference Room A

    Thursday, April 30, 2015, 11:00 am

    Hosted by: James Dickerson

    The theme of this presentation is the use of microstructural control to extend the favorable attributes of "Nano", and minimize the undesirable ones, in relation to lithium ion batteries (LIBs), sodium ion batteries (SIBs) and electrochemical supercapacitors. In this talk I will cover several examples where proper microstructural design provides substantial improvements: A) The use of nanoscale coatings to more than double the cycling capacity retention and achieve near 100% coulombic efficiency of Si nanowire and nanotube LIB anodes; B) Fabricating improved materials for Na ion battery anodes through tailored metal alloys and pseudographitic carbons; C) Converting a common livestock biowaste, in the form of chicken eggshell membranes and inedible egg whites, to electrodes with some of the highest specific capacitances and Li storage capacities reported in literature for any carbon; D) Creating carbons with electrochemical performance on par or even better than graphene for a range of energy storage devices, from hemp fibers, banana peels and peat moss. In all cases I will detail the key synthesis ��" microstructure features that transform the performance of these materials from mundane to remarkable. Recent media coverage: http://www.altmetric.com/details.php?citation_id=1462145&src=bookmarklet

  2. MAY

    31

    Sunday

    CFN Proposal Deadline

    "CFN Proposal Deadline for September-December Cycle 2015"

    11:45 pm, CFN

    Sunday, May 31, 2015, 11:45 pm

  3. SEP

    30

    Wednesday

    CFN Proposal Deadline

    "CFN Proposal Deadline for January-April Cycle 2016"

    11:45 pm, CFN

    Wednesday, September 30, 2015, 11:45 pm