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Showing Spotlights 665 - 672 of 2023 in category (newest first):

 

Nanotechnology in construction

buildingIn the construction industry and in architecture, nanotechnology and nanomaterials provide new opportunities. 'Nano-products' for construction purposes are currently found in four main sectors: cement-bound construction materials, noise reduction and thermal insulation or temperature regulation, surface coatings to improve the functionalities of various materials, and fire protection. At the present time, nanomaterials - and therefore 'nano-products' - remain considerably more expensive than conventional alternatives due to the required production technology, and the technical performance of many products remains to be demonstrated. Also, Information on which nanomaterial is found in which form and concentration in a product is often unavailable, particularly to end users.

Posted: Sep 13th, 2012

Surface chemistry of silver nanoparticles and cell death

silver_nanoparticlesSilver nanoparticles are among the most commercialized nanomaterials due to their use as antibacterial agent in consumer products and surface coatings. Several reports have shown that silver ions from silver compounds or those that develop from nanosilver particles through contact with water are highly toxic to microorganisms such as bacteria, fungi and algae. Contributing to an incomplete and confusing picture, in the literature, silver nanoparticles are claimed as nontoxic or toxic depending on their size, concentration and surface functionalization. Researchers have now reported on possible adverse effects of the silver nanoparticles upon their release into the environment and provided novel insights into the possible applications of silver nanoparticles in nanomedicine by discussing their p53 gene related cell death profiles.

Posted: Sep 12th, 2012

Nanoparticle approach to simultaneously deliver proteins and DNA into plant cells

multifunction_nanoparticleNanotechnology is gaining significant interest in plant sciences with research focusing on investigating plant genomics and gene function as well as improving crop species. The impact on agriculture could be dramatic. Most of the work done with nanoparticles in plant sciences relies on a passive uptake of nanoparticles by plant cells - a process that cannot be controlled. Plant cells differ from animal cells in several aspects, a major one being that they possess a wall surrounding them to provide, among other things, mechanical and structural support. Researchers are commonly using surface-functionalized silica nanoparticles as nonviral nanocarriers for experimental drug and DNA delivery into animal cells but their use with plants so far was limited due to the barriers posed by the cell wall. Following up on previous work, researchers have made this process more efficient and introduced a much more challenging biomolecule to plant cells - proteins.

Posted: Sep 10th, 2012

A lithography technique for fabricating complex, free-floating protein structures

microstructureMultiphoton lithography (MPL) is a microfabrication technique used to create three-dimensional microscale objects with complex geometrical arrangements. Of the various chemistries used to produce solid forms in MPL, protein photocrosslinking has been of particular value in biological applications. In new work, researchers have now described a strategy for creating a nearly unlimited range of microforms from crosslinked protein, including structures composed of multiple proteins. They also describe MPL microfabrication of complex unconstrained objects using high-viscosity protein-based reagents. To avoid drift during fabrication of microforms that are not in integral contact with a surface, the team developed a methodology for producing high-viscosity protein-based reagents, or "protogels". These materials allow the fabrication of protein-based objects that retain rotational and translational degrees of freedom.

Posted: Sep 6th, 2012

Highly asymmetric line nanopatterning becomes possible with block copolymer self-assembly

nanopatternsLithography based on block copolymer self-assembly has received significant attention due to the ability to achieve morphologies with dimensions in the range of 10 to 20 nm or even below. Block copolymer lithography is a cost-effective, parallel, and scalable nanolithography for densely packed periodic arrays of nanoscale features, whose typical dimension scale is beyond the resolution limit of conventional photolithography. Researchers have now introduced a conceptually new and versatile strategy to achieve asymmetric line patterns. This is the first work to demonstrate that highly asymmetric line nanopatterning is possible even though a block copolymer self-assembly technique is used.

Posted: Sep 5th, 2012

Extremely water repellent graphene foams

water-repellingResearchers have shown that it is possible to use graphene sheets to create a superhydrophobic coating material that shows stable superhydrophobicity under both static as well as dynamic (droplet impact) conditions. They demonstrates a novel macroscopic graphene structure composed of an integrated foam-like network of graphene sheets with well-controlled microscale porosity and roughness. The novel idea here was to grow graphene over a sacrificial nickel foam template and then leech away the nickel, leaving behind a graphene foam with few-layered graphene sheets that comprise the walls of the foam. The foam is then coated with a 200nm layer of Teflon.

Posted: Sep 4th, 2012

Unique porous carbon spheres made by ultrasonic spray pyrolysis

carbon_nanospheresUltrasonic spray pyrolysis (USP) has been widely used in industry for spherical solid powder production, particularly of metal oxides. For some applications, though, porous particles are more desirable than dense ones. Back in 2005, researchers developed a technique to synthesize porous micro- and nanoparticles via USP. This method has since been expanded to prepare porous carbon microspheres. The high surface area and unique porous structures suggest that porous carbon spheres can be useful for electrode materials, adsorbents, and catalyst supports. Researchers at the University of Illinois already demonstrated the use of carbon microspheres as supercapacitors. Now, the team has expanded the aerosol synthesis of porous carbon materials by the use of energetic carbon precursors. Some of the resulting porous carbon spheres exhibit unique and unprecedented morphologies.

Posted: Sep 3rd, 2012

The challenge of testing nanomaterial ecotoxicity in aquatic environments

algal_cellsAquatic ecotoxicity test methods, which are routinely applied to testing of nanomaterials, were originally developed for water soluble chemicals. Nanomaterials are fundamentally different from many 'conventional' chemicals as they often have limited or no solubility at all and are potentially released to the environment in a particulate form (e.g. carbon nanotubes). Only limited nano-specific guidance on ecotoxicity testing is currently available, for instance existing OECD ecotoxicity test guidelines to nanomaterials. These guidelines exhibit a number of specific shortcomings mainly related to characterization, exposure preparation, quantification and monitoring concentrations, and dose-metrics. A new paper from scientists in Denmark contributes to the progress in algae testing of nanomaterials. This work also aids in the development of additional guidance as it adds to the understanding of pros and cons of different techniques for biomass quantification.

Posted: Aug 31st, 2012