BNL Home
May 2016
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  1. Center for Functional Nanomaterials Seminar

    11 am, Bldg 735, Conference Room B

    Hosted by: 'Chang-Yong Nam'

    Membrane-based technologies are energy efficient and have a small footprint, making them economically attractive candidates to help address our water and energy needs. Ion exchange membranes (i.e., charged membranes, ionomers, etc.) are critical for efficient operation of a number of membrane-based technologies such as electrodialysis, reverse electrodialysis, fuel cells, etc., due to their ability to effectively control rates of water and ion transport. Efforts are also underway to harness their separation properties for applications that have not traditionally used them (e.g., reverse osmosis, pressure retarded osmosis, etc.). One avenue for improving these technologies is to develop more effective membranes. Rational design of high performance membranes could be catalyzed by fundamental knowledge of the connection between polymer structure (physical or chemical) and transport properties. However, despite the long history of literature on the topic and the industrial importance of such materials, the current state of understanding is incomplete. Experimental techniques for characterizing ion sorption and transport in charged membranes have been established, however, a simple theoretical framework for interpreting the experimental findings is missing. In this study, a framework for ion sorption and diffusion in charged membranes based upon ideas from polyelectrolyte theory (e.g., counter-ion condensation) has been formulated and tested against experimental data. For the membranes considered in this study, the framework accurately described, and in some cases predicted, concentration gradient (i.e., salt permeability) and electric field (i.e., ionic conductivity) driven ion transport. The main factors governing ion sorption and transport in charged polymers are discussed. Our long-term goal is to use such knowledge to establish structure/property relations leading to rational design of membranes with improved performance.

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  1. Center for Functional Nanomaterials Seminar

    1:30 pm, Bldg 735, Conference Room A, 1st Floor

    Hosted by: ''Oleg Gang''

    A living cell is a complex soft matter system that is far from equilibrium. While its components have definite mechanical properties like stiffness and viscosity, cells consume energy to generate force and exhibit adaptation by modulating their mechanical properties through regulatory pathways. In this work, we explore cell mechanics by stretching single fibroblast cells and simultaneously measuring their traction stresses. We show that a minimal active linear viscoelastic model captures essential features of cell response, especially during early times shortly after stretch. On longer time scales, cells often exhibit an adaptive response to stretch that contradicts the minimal mechanical model. We find that while molecular perturbations of myosin and vinculin change quiescent traction stresses, surprisingly they have no significant impact on the stiffness or viscoelastic timescale of the cell response.

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  1. CFN Colloquium

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

    Hosted by: ''''''Chuck Black''''''

    Photonics on chip could enable a platform for monolithic integration of optics and microelectronics for applications of optical interconnects in which high data streams are required in a small footprint. This approach could alleviate some of the current bottlenecks in traditional microelectronics. In this talk I will review the challenges and achievement in the field of Silicon Nanophotonics and present our recent results. Using highly confined photonic structures, much smaller than the wavelength of light, we have demonstrated ultra-compact passive and active silicon photonic components that enhance the electro-optical, mechanical and non-linear properties of Silicon. Based on the ability to dynamically modulate light on the same time scale as the time of flight we have demonstrated novel GHz structures for a variety of applications including all-optical synchronized RF oscillators and optical isolators on a silicon chip. Michal Lipson is the Higgins Professor of Electrical Engineering at Columbia University, New York, NY. Her research focuses on novel on-chip Nanophotonics devices. She has pioneered several of the critical building blocks for silicon photonics including the GHz silicon modulators. Professor Lipson's honors and awards include 2010 Macarthur fellow, NYAS Blavatnik award, OSA Fellow, IBM Faculty Award, and NSF Early Career Award. More information on Professor Lipson can be found at http://lipson.ee.columbia.edu/

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  1. JUN

    2

    Thursday

    CFN Colloquium

    "Graphene Synthesis and Devices"

    Presented by Dr. James Tour, Rice University

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

    Thursday, June 2, 2016, 11:00 am

    Hosted by: 'Dmitri Zakharov'

    An in-depth look at numerous methods to make graphene, ranging from single-crystal sheets that grown in precise hexagonal arrays to growth of graphene in air at room temperature using lasers, and 2- and 3-D hybrid graphene nanotube structures. Use of the graphene materials in composites will be discussed. Many of the devices made and their transitions to industry will be shown. These devices include fuel cells, water splitting systems, batteries, supercapacitors and more.

  2. JUN

    3

    Friday

    Center for Functional Nanomaterials Seminar

    "Research in Chemical Sciences at University of Warsaw: from General Information to Activities in Area of Electrocatalytic Functional Materials"

    Presented by Pawel J. Kulesza, University of Warsaw, Poland

    11 am, CFN, Bldg 735 Conference Room A, 1st Floor

    Friday, June 3, 2016, 11:00 am

    Hosted by: '''Pawel Majewski'''

    My research is focused on rational design of materials for efficient electrocatalysis and electrochemical energy conversion and storage. In particular, I am interested in electrochemical reduction of carbon dioxide, a potent greenhouse gas and a contributor to global warming. Given the fact that the CO2 molecule is very stable, its electroreduction processes are characterized by large overpotentials. To optimize the hydrogenation-type electrocatalytic approach, we have utilized nanostructured metallic centers (e.g. Pd, Pt or Ru) in a form of highly dispersed nanoparticles generated within a supramolecular network of distinct N-, S- or oxygen-coordination complexes. Another possibility to enhance electroreduction of carbon dioxide is to explore direct transformation of solar-to-chemical energy using transition metal oxide semiconductors. We showed that, by controlled combination of semiconducting oxides (TiO2 and Cu2O), we were able to drive photoelectrochemical reduction of carbon dioxide mostly to methanol. Application of mixed-metal oxides as active matrices is important in electrocatalytic oxidation of small organic molecules in low-temperature fuel cells. The oxide's chemical properties and morphology, which favor hydrous proton mobility affect the overall reactivity during oxidation of ethanol (e.g. at PtRu). When metal nanoparticles were dispersed between WO3 and ZrO2 layers, significant current enhancements were observed. The result can be rationalized by the mechanism in which Rh induces splitting of C-C bonds in C2H5OH molecules before the actual electrooxidation. We also consider nanoelectrocatalytic systems permitting effective operation of the iodine-based dye sensitized solar cells. The ability of Pd or Pt nanostructures to induce splitting of I-I bonds in the triiodide molecules is explored here to enhance electron transfers in the triiodide/iodide-containing 1,3-dialkylimidazolium ionic liquids.

  3. JUN

    9

    Thursday

    Center for Functional Nanomaterials Seminar

    "Molecular Cluster as Superatoms in Solid-State Chemistry"

    Presented by Xavier Roy, Columbia University

    1:30 pm, CFN, Bldg 735, Conference Room A, 1st Floor

    Thursday, June 9, 2016, 1:30 pm

    Hosted by: ''''Matthew Sfeir''''

    Traditional solid-state compounds are infinite crystalline arrays of densely packed atoms. The emergence of collective properties in structured clusters of atoms, which we term "superatoms", offers a new class of fundamental building blocks for assembling materials. The superatom concept has the potential to usher in a new era where materials are designed to have a specific function, rather than discovered by trial and error. To realize this concept, we are exploring the use of molecular clusters as superatomic building blocks, designing and synthesizing not only the molecular clusters but also the means by which they interact. In this presentation, I will show how the atomic control and the diversity afforded by our superatoms allows us to dictate the structure of the solids and control the interactions between the building blocks. I will discuss how collective properties emerge from these interactions by providing examples of magnetic phase transition, electrical transport and thermal energy transport.

  4. JUL

    17

    Sunday

    Summer Sunday

    "Exploring the Ultra Small: The Center for Functional Nanomaterials"

    10 am, Berkner Hall for Information

    Sunday, July 17, 2016, 10:00 am

    Tour the Center for Functional Nanomaterials, where Brookhaven scientists study structures as tiny as a billionth of a meter.