Showing Spotlights 1129 - 1136 of 2140 in category (newest first):
Along with graphene, boron nanoribbons have attracted more and more fundamental research interest. However, a major challenge in providing experimental evidence is that the preparation of atomically thin boron nanoribbons is very difficult. In new work that represents an important step in bridging theoretical predictions and experimental realization of atomically thin boron nanoribbons, reseaerchers demonstrate the successful fabrication of 'white graphene' nanoribbons - made of thermally and chemically stable atomic layers of hexagonal boron nitride - by unwrapping multiwalled boron nanotubes under delicate argon plasma etching. They show that the insulator-semiconductor electrical transition takes place during this processing and that this typically electrically insulating compound becomes a semiconductor when it is in ribbon morphology.
Nov 9th, 2010
In a new research field that could be called 'experimental nanotoxicology', scientists have now, for the first time, demonstrated that biological effects of manufactured nanoparticles can be predicted using their chemical, physical, and geometrical properties. The results successfully demonstrate the high potential of cheminformatics approaches for improving the experimental design and prioritizing the biological testing of novel manufactured nanoparticles. The team modeled their approach after a process used in drug design and chemical synthesis, where the chemical structure of a new compound is quantitatively correlated with a well defined process, such as biological activity or chemical reactivity. Such a Quantitative Structure Activity Relationship (QSAR) can then be utilized to help guide chemical synthesis and drug design. They termed their approach quantitative nanostructure-activity relationship (QNAR) modeling.
Nov 8th, 2010
Nanocatalysis - the use of nanoparticles to catalyze reactions - is a rapidly growing field which involves the use of nanomaterials as catalysts for a variety of homogeneous and heterogeneous catalysis applications. Heterogeneous catalysis represents one of the oldest commercial practices of nanoscience; nanoparticles of metals, semiconductors, oxides, and other compounds have been widely used for important chemical reactions. Since nanoparticles have a large surface-to-volume ratio compared to bulk materials, they are attractive candidates for use as catalysts. Although surface science studies have contributed significantly to our fundamental understanding of catalysis, most commercial catalysts, are still produced by 'mixing, shaking and baking' mixtures of multi-components; their nanoscale structures are not well controlled and the synthesis-structure-performance relationships are poorly understood.
Nov 5th, 2010
Researchers at Harvard University have shown that nanostructures can be patterned with focused electron or ion beams in thin, stable, conformal films of water ice grown on silicon. They demonstrated ice lithography as a lithographic technique for patterning e.g. metal wires down to 20 nm wide. What's interesting about this technique is that patterning with ices of any condensed gas is a straightforward and practical process. Ice resist does not require spinning or baking. All processing and patterning steps can occur in a single evacuated chamber and be monitored at high resolution. The final removal of unexposed resist leaves minimal residues. Environmentally harmful solvents are not required and complete dry removal of the ice layer can be performed by in situ sublimation. Also, ice lithography makes it possible to nanopattern chemical modifications into silicon and other substrates. The team has now reported the successful application of ice lithography to the fabrication of nanoscale devices.
Nov 4th, 2010
Understanding the behavior and impacts of nanomaterials in the environment and in human health is a daunting task. Today, we don't even know what the impact of most chemicals is, and that includes products we have been using for many years. Nevertheless, a general understanding about nanotoxicity is slowly emerging as the body of research on cytotoxicity, genotoxicity, and ecotoxicity of nanomaterials grows. Many of the published toxicity studies have limited relevance, due, in large part, to study design limitations, including inadequate justification for dose selection or route of exposure criteria. A recently published article addresses myths and misconceptions regarding nanotoxicology.
Nov 2nd, 2010
Compared to silicon-based devices, polymer solar cells made of conducting plastic material are lightweight, relatively inexpensive to fabricate, flexible, designable on the molecular level, and have little potential for negative environmental impact. The big question today is to what degree polymer solar cells will be able to commercially compete with silicon solar cells. With the exciting vision of organic solar cells becoming a low-cost electricity source available in any size and shape, as flexible thin films and even coatings, researchers all over the world are working on making organic solar cells commercially attractive. Finding a relatively simple way of polymerizing fullerenes and including this new material in photovoltaic cells, researchers have opened a route towards plastic solar cells that are much cheaper and easier to fabricate than conventional silicon-based photovoltaic panels.
Nov 1st, 2010
A relatively new method of purifying brackish water is capacitive deionization (CDI) technology. The advantages of CDI are that it has no secondary pollution, is cost-effective and energy efficient. The basic concept of CDI, as well as electrosorption, is to force charged ions toward oppositely polarized electrodes through imposing a direct electric field: brackish water flows between pairs of high surface area carbon electrodes that are held at a potential difference of about 1-2 volts. The ions and other charged particles, such as microorganisms, are attracted to and held on the electrode of opposite charge. A research team has now developed a CDI application that uses graphene-like nanoflakes as electrodes for capacitive deionization. They found that the graphene electrodes resulted in a better CDI performance than the conventionally used activated carbon materials.
Oct 27th, 2010
In atomic force microscopy (AFM), tip quality depends mainly on the dimensions and shape of the probe, the durability of the tip apex, and the nature of the interaction between sample and probe. With this in mind, researchers have experimented with mounting ultra sharp and high aspect ratio carbon nanotube (CNT) bundles onto the apex of an AFM tip to improve spatial and potential resolution. Although AFM tips functionalized with a carbon nanotube have attracted considerable attention, attaching CNTs to scanning probes is not a trivial matter, which limits their practical use. An alternative approach, whereby a CNT is grown onto the AFM tip, also can be very time-consuming and requires a costly set-up. A team at the Friedrich-Schiller-University Jena in Germany has now demonstrated a fast and cheap process for the fabrication of carbon nanotube AFM tips with the help of microwave ovens.
Oct 26th, 2010