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Nanotechnology Spotlight

Behind the buzz and beyond the hype:
Our Nanowerk-exclusive feature articles

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Showing Spotlights 1545 - 1552 of 1688 in category (newest first):

 

Nanotechnology in cosmetics - 2000 years ago...?

These days we are debating if nanoparticles in sunblock and toothpaste are safe. The ancient Greeks and Romans didn't know about such things - but they already used nanotechnology in their cosmetics. A group of researchers in France showed that lead-based chemistry, which was initiated in Egypt more than 4000 years ago, could result in the synthesis of lead sulfide (PbS, galena) nanocrystals. With a diameter of about 5 nm, the appearance of these crystals is quite similar to PbS quantum dots synthesized by modern materials science techniques.

Posted: Sep 5th, 2006

Low temperature fabrication of CNTs for field emission displays

Carbon nanotubes (CNTs) are considered the most promising material for field emitters and a practical example are CNTs as electron emitters for field emission displays (FED). CNT emitters are generally fabricated by indirect growth methods such as screen-printing and electrophoresis. These methods show advantages in lowering the coating temperature and scale-up of the substrate size, but the direction of CNTs cannot be well controlled and a post-treatment process is generally necessary to enhance the performance of CNT emitters. In contrast to the indirect method, chemical vapor deposition (CVD) is a common technique for growing nanotubes directly on the substrate with the assistance of metallic catalysts. With the CVD method, CNTs can be grown at desired locations with a specified direction. However,most synthesis technologies such as conventional thermal CVD or plasma enhanced CVD are performed at temperatures over 500 C, which may restrict the application of CNTs on plastic substrates. Therefore, lowering the growth temperature for CNTs is one of the important directions for facilitating CNT applications.

Posted: Sep 1st, 2006

DNA as template for assembling nanostructures

Recent developments in DNA-based nanotechnology have shown the suitability of this novel assembly method for constructing useful nanostructures. DNA molecules can serve as precisely controllable and programmable scaffolds for organizing functional nanomaterials in the design, fabrication, and characterization of nanometer scale electronic devices and sensors. DNA-templated metallic nanowires are such an example and over the past few years DNA scaffolds have been metallized with silver, gold, palladium, platinum and copper. DNA-based fabrication methods could ultimately lead to naturally bio-compatible nanodevices.

Posted: Aug 31st, 2006

The flip side of using carbon nanotubes for environmental pollutants removal

Carbon nanomaterials have been studied as superior sorbents for their potential environmental applications to remove pollutants such as organic pollutants, metals, fluorides and radionuclides. Most of these studies focused on the adsorption process and few dealt with the interfacial interactions of organic contaminants with carbon nanomaterials in aqueous media. However, understanding their desorption behavior as well is critical to evaluating environmental and health impacts of carbon nanomaterials. New research looks at the high adsorption capacity and reversible adsorption of PAHs (polycyclic aromatic hydrocarbons), many of which are suspected carcinogens, on CNTs. The findings imply the potential release of PAHs if PAH-adsorbed CNTs are inhaled by animals and humans, leading to a high environmental and public health risk.

Posted: Aug 30th, 2006

Numbering up: The use of microreactors for nanomanufacturing

Microscale reactor technology has tremendous advantage over conventional macro-scale or batch chemical processes, and offers versatility for a wide range of applications including chemical analyses, drug discovery, radiotracer synthesis, and the fabrication of engineered nanomaterials. Attention is currently focused on developing scaleable process regimes, using an approach engineers call numbering up. Microreactor technology is defined by a series of interconnected, functionally distinct channels formed on a planar surface, utilizing either hydrodynamic or (EOF) for pumping, with channel dimensions typically between 10-300 microns.

Posted: Aug 29th, 2006

Infrared imaging of sub-10 nm particles

Objects a thousand times smaller than the wavelength of infrared light (10 micrometers) are undetectable by standard far-field optical infrared microscopy since the weak nanoparticle signals would be buried far below the background level. To overcome this drawback and to achieve nanoscale spatial resolution researchers in Germany illuminate the nanoparticles by a highly intensive nanoscale infrared light spot. It is generated in the nano-gap between a laser-illuminated scanning metal tip and the substrate supporting the particles. The simple but very efficient trick finally allowing detection of sub-10 nm particles is the use of highly reflecting substrates instead of glass slides typically used as a sample carrier in optical microscopy.

Posted: Aug 28th, 2006

Template-free synthesis of hollow nanostructures

Among many nanomaterials with distinct geometric shapes, spheres and cubes are the two simplest forms, yet they possess the highest symmetries. One of the obvious geometric merits of this class of materials is their low resistivity under fluidic conditions, as they can be essentially considered as zero-dimensional entities when their size is trimmed down to the nanoscale regime. So far, most hollow interiors of nanomaterials are created by template-methods. Researchers in Singapore for the first time demonstrated that nanostructured polyhedrons of functional materials with desired interiors can be synthesized template-free through a simple hydrothermal method.

Posted: Aug 25th, 2006

Nanoscience and nanotechnology in Latin America

The year 2005 was an important year for nanoscience and nanotechnology in Latin America. Brazil increased federal funding for its nanotechnology program. In Mexico, the Senate Committee for Science and Technology declared itself in favor of the development of a National Emergency Program for investment in research and teaching of nanotechnology. In Colombia, the National Council of Nanoscience and Nanotechnology was created. But all this was not done without controversy; and it was in Argentina that conflicts in the scientific and political spheres were concentrated, with repercussions in the media. In Argentina, many of the things that took place in a short span of time might take longer than in many other Latin American countries.

Posted: Aug 24th, 2006