199 research outputs found

    Effect of varying the composition and nanostructure of organic carbonate-containing lyotropic liquid crystal polymer electrolytes on their ionic conductivity

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    Nanostructured composite electrolyte films consisting of a cross-linked lyotropic liquid crystal (LLC) monomer, an organic carbonate liquid electrolyte (propylene carbonate, dimethylcarbonate, diethylcarbonate) and a Li salt (LiClO_4, LiBF_4, LiPF_6) were systematically prepared and characterized at two electrolyte concentrations (0.245 and 1.0 m) and four liquid loading levels (5, 15, 30, 50 wt %). The LLC morphology of the films was investigated using polarized light microscopy and powder X-ray diffraction; their ionic conductivity was investigated using AC impedance measurements. Higher liquid electrolyte loadings and Li salt concentrations generally increased ionic conductivity, regardless of the liquid electrolyte or salt used. Some mixed-phase LLC morphologies displayed good ionic conductivity; however, as initially prepared, these formulations were at the limit of liquid uptake. In contrast, composites with a type II bicontinuous cubic (QII) LLC phase containing ordered, three-dimensional interconnected nanopores exhibited good conductivity using much less liquid electrolyte and a lower Li salt concentration, indicating that this structure is more amenable to ion transport than less ordered/uniform morphologies. When wetted with electrolyte solution and integrated into Li/fluorinated carbon coin cells, the QII films were sufficiently strong to act as an ion-conductive separator and displayed stable open-circuit potentials. Many of the mixed-phase films gave shorted cells

    A Rootstock Provides Water Conservation for a Grafted Commercial Tomato (<i>Solanum lycopersicum</i> L.) Line in Response to Mild-Drought Conditions: A Focus on Vegetative Growth and Photosynthetic Parameters

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    <div><p>The development of water stress resistant lines of commercial tomato by breeding or genetic engineering is possible, but will take considerable time before commercial varieties are available for production. However, grafting commercial tomato lines on drought resistant rootstock may produce drought tolerant commercial tomato lines much more rapidly. Due to changing climates and the need for commercial production of vegetables in low quality fields there is an urgent need for stress tolerant commercial lines of vegetables such as tomato. In previous observations we identified a scion root stock combination (‘BHN 602’ scion grafted onto ‘Jjak Kkung’ rootstock hereafter identified as 602/Jjak) that had a qualitative drought-tolerance phenotype when compared to the non-grafted line. Based on this initial observation, we studied photosynthesis and vegetative above-ground growth during mild-drought for the 602/Jjak compared with another scion-rootstock combination (‘BHN 602’ scion grafted onto ‘Cheong Gang’ rootstock hereafter identified as 602/Cheong) and a non-grafted control. Overall above ground vegetative growth was significantly lower for 602/Jjak in comparison to the other plant lines. Moreover, water potential reduction in response to mild drought was significantly less for 602/Jjak, yet stomatal conductance of all plant-lines were equally inhibited by mild-drought. Light saturated photosynthesis of 602/Jjak was less affected by low water potential than the other two lines as was the % reduction in mesophyll conductance. Therefore, the Jjak Kkung rootstock caused aboveground growth reduction, water conservation and increased photosynthetic tolerance of mild drought. These data show that different rootstocks can change the photosynthetic responses to drought of a high yielding, commercial tomato line. Also, this rapid discovery of one scion-rootstock combination that provided mild-drought tolerance suggests that screening more scion-rootstock combination for stress tolerance may rapidly yield commercially viable, stress tolerant lines of tomato.</p></div

    Encapsulating nanoparticle arrays into layer-by-layer multilayers by capillary transfer lithography

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    We introduce capillary transfer lithography for the fabrication of ordered microscopic arrays from nanoparticulate materials encapsulated into ultrathin (<100 nm) flexible polymer films. Well-defined polymer micropatterns have been fabricated by capillary transfer lithography and used as a protective template for guided assembly of nanoparticles on layer-by-layer (LbL) multilayers. Sequential removal of this template facilitates further assembly of a topmost polyelectrolyte film, hence completing encapsulation. The striped and chess-board arrays of a single layer of carbon nanotubes and gold nanoparticles were sandwiched between two polymer LbL multilayers of thickness 19 nm each.close524

    Single-Molecule AFM Characterization of Individual Chemically Tagged DNA Tetrahedra

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    Single-molecule characterization is essential for ascertaining the structural and functional properties of bottom-up DNA nanostructures. Here we enlist three atomic force microscopy (AFM) techniques to examine tetrahedron-shaped DNA nanostructures that are functionally enhanced with small chemical tags. In line with their application for biomolecule immobilization in biosensing and biophysics, the tetrahedra feature three disulfide-modified vertices to achieve directed attachment to gold surfaces. The remaining corner carries a single bioligand that can capture and present individual cargo biomolecules at defined lateral nanoscale spacing. High-resolution AFM topographic imaging confirmed the directional surface attachment as well as the highly effective binding of individual receptor molecules to the exposed bioligands. Insight into the binding behavior at the single-molecule level was gained using molecular recognition force spectroscopy using an AFM cantilever tip with a tethered molecular receptor. Finally, simultaneous topographic and recognition imaging demonstrated the specific receptor–ligand interactions on individual tetrahedra. In summary, AFM characterization verified that the rationally designed DNA nanostructures feature characteristics to serve as valuable immobilization agents in biosensing, biophysics, and cell biology

    High Energy Neutrinos and Photons from Curvature Pions in Magnetars

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    We discuss the relevance of the curvature radiation of pions in strongly magnetized pulsars or magnetars, and their implications for the production of TeV energy neutrinos detectable by cubic kilometer scale detectors, as well as high energy photons.Comment: 19 pages, 4 figures, to appear in JCA