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Nanotechnology Spotlight

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

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Showing Spotlights 1321 - 1328 of 1649 in category (newest first):

 

Ethanol production inside carbon nanotubes

Ethanol is all the rage these days. Although we have been drinking ethanol, an alcohol, for thousands of years (fermented beverages such as beer and wine may contain up to 15-25% ethanol by volume), the recent interest has been sparked by its use as a renewable fuel alternative to gasoline. Indeed, the largest single use of ethanol is as a motor fuel and fuel additive. Ethanol is produced by fermentation when certain species of yeast metabolize sugar. The process works with all biological feedstocks that contain appreciable amounts of sugar or materials that can be converted into sugar such as starch or cellulose. The primary feedstock for ethanol production in the U.S. is corn. In Brazil, the world's leading ethanol producer, it's mostly derived from sugar cane. While there is a heated controversy over the economic and ecological benefits of using biomass for producing ethanol fuel, it seems that nanotechnology's jack-of-all-trades, the carbon nanotube (CNT), might provide a solution here as well. CNTs are increasingly recognized as promising materials for catalysis, either as catalysts themselves, as catalyst additives or as catalyst supports. Researchers in China now have used CNTs loaded with rhodium (Rh) nanoparticles as reactors to convert a gas mixture of carbon monoxide and hydrogen into ethanol. This appears to be the first example where the activity and selectivity of a metal-catalyzed gas-phase reaction benefits significantly from proceeding inside a nanosized CNT reaction vessel.

Posted: Jun 8th, 2007

New fabrication techniques could get OLEDS ready for the big screen

OLEDs - organic light-emitting diodes - are full of promise for a range of practical applications not too far into the future. Today, OLEDs are used in small electronic device displays in mobile phones, MP3 players, digital cameras, etc. With more efficient and cheaper OLED technologies we soon will see ultraflat, very bright and power-saving OLED televisions, windows that could be used as light source at night, and large-scale organic solar cells. In contrast to regular LEDs, the emissive electroluminescent layer of an OLED consists of a thin-film of organic compounds. What makes OLEDs so attractive is that they do not require a backlight to function. Thus they draw far less power and, when powered from a battery, can operate longer on the same charge. OLED devices can be made thinner and lighter than comparable LED devices. Last but not least, OLEDs can be printed onto almost any substrate with inkjet printer technology, making new applications like displays embedded in clothes or roll-up displays possible. Unfortunately there are also drawbacks to this technology. Apart from its currently high manufacturing cost, the major problem is device degradation and the limited lifetime of organic materials. In particular, the most commonly used material for the anode, ITO (indium tin oxide), is a less than optimal material for future high-performance OLEDs. New research indicates that nanoimprinted semitransparent metal electrodes, replacing ITO electrodes, are an attractive and potentially practical solution for OLEDs and other organic devices.

Posted: Jun 7th, 2007

Horseradish, carbon nanotubes and cancer therapy

Scientists involved in cancer research are showing a lot of interest in carbon nanotubes (CNTs) to be used in basically three cancer-fighting areas. CNTs are being developed as targeted delivery vehicles for anticancer drugs right into cancer cells - think of really, really tiny injection needles. They are also used as the therapeutic agent itself; there is research that shows that CNTs can act as nanoscale bombs that literally blow apart a cancer cell. A third area of application is using CNTs as imaging agents. Particularly single-walled CNTs (SWCNTs) are under active development for various biomedical applications. One of the issues in using CNTs for therapeutic applications is the question of how to get them to the desired place within the organism, say a tumor cell. Another significant problem in applying CNTs for biological applications is that the nanotubes do not stay suspended as discrete nanotubes in aqueous solutions. Coupling the CNT with biomolecules, such as proteins, is a good method for targeting specific sites but has the disadvantage of either reducing protein activity or CNT absorption or both. A novel method demonstrates that it is possible to achieve complete retention of enzymatic activity of adsorbed proteins as well as retention of a substantial fraction of the near-infrared (NIR) absorption of SWCNTs.

Posted: Jun 6th, 2007

Regulating nanotechnology - incremental approach or new regulatory framework?

In 2005, the Project on Emerging Nanotechnologies released a report by Dr. J. Clarence Davies (Managing the effects of nanotechnology) that found that U.S. legislation was inadequate. Davies concluded that nanotechnology is difficult to address using existing regulations and a new regulatory framework was needed in order to take the unique properties and risks of nanomaterials into account. This was in somewhat contradiction to what the EU Commission had found after its preliminary risk assessment workshop in 2004. The European Commission concluded that the European Union could protect health and environment by using an incremental approach and adapt existing legislation. Although there are cultural and legal differences between the EU and U.S., some people had a hard time understanding how the conclusions of the two reports could be so different. Among them, a group of scientists in Denmark and Italy decided to take a very product-specific approach and analyze the existing legislation along the life-cycle of three different commercially available products containing nanomaterials. They conclude that the 'incremental approach' could work effectively, provided due explanations and amendments are taken where necessary.

Posted: Jun 5th, 2007

DNA wrappers for carbon nanotubes

To achieve the full benefits of the amazing properties of carbon nanotubes (CNTs) researchers are exploring all kinds of CNT composite materials. Material engineers are interested because this will lead to lighter,stronger and tougher materials. Another fascinating area involves CNT/polymer composite structures that will lead to a vast range of improved and novel applications, from antistatic and EMI shielding to more efficient fuel and solar cells, to nanoelectronic devices. One particular area of CNT/polymer composites is dealing with DNA-CNTs hybrids. Although researchers expect a plethora of new applications, the fact that even the formation mechanism of these complexes is not yet clear shows how early in the game this research still is. This might be due to the fact that in spite of the quite large number of experimental investigations on the interaction between DNA and CNTs, the number of theoretical studies is limited. Researchers in Germany now present, for the first time, the results of a systematic quantum mechanical modeling of the stability and the electronic properties of complexes based on single-walled carbon nanotubes, which are helically wrapped by DNA molecules.

Posted: Jun 4th, 2007

Green nanotechnology - turning diesel soot into carbon nanotubes

Diesel-burning engines are a major contributor to environmental pollution. They emit a mixture of gases and fine particles that contain some 40, mostly toxic chemicals, including benzene, butadiene, dioxin and mercury compounds. Diesel exhaust is listed as a known or probable human carcinogen by several state and federal agencies in the United States. Wouldn't it be nice if we could render diesel soot harmless before it gets released into the environment? Wouldn't it even be nicer if we could use this soot to manufacture something useful? Japanese scientists have come up not only with a unique technique for effectively collecting diesel soot but also a method for using this soot as a precursor for the production of single-walled carbon nanotubes. How is that as a practical example for green nanotechnology?

Posted: May 30th, 2007

How to build a nanothermometer

One of the problems nanoscientists encounter in their forays into the nanoworld is the issue of accurate temperature measurement. Ever since Galileo Galilei invented a rudimentary water thermometer in 1593, accurate temperature measurement has been a challenging research topic and thermosensing technologies have become a field in their own right. Now, that technology has reached the nanoscale, temperature gradients are becoming essential in areas such as thermoelectricity, nanofluidics, design of computer chips, or hyperthermal treatment of cancer. Currently there is no established method how to measure the temperature gradients at the nanoscale. Most of today's probes are traditional bulk probes, the kind that gets inserted into a sample and measures the temperature. Liquid crystal films which change colors depending on temperature also have at least microscale thickness and lateral dimensions. A recent review addresses these issues and gives an overview of current and future developments for nanoscale temperature measurement technologies.

Posted: Jun 1st, 2007

Blowing bubbles - from cling wrap to nanotechnology electronics

One of the most common methods of film manufacture is Blown Film Extrusion. The process, by which most commodity and specialized plastic films are made for the packaging industry, involves extrusion of a plastic through a circular die, followed by "bubble-like" expansion. The resulting thin tubular film can be used directly, or slit to form a flat film. Nanoscientists now have found a way to use this very common and efficient industrial technology to potentially solve the problem of fabricating large-area nanocomposite films. Currently, the problems with making thin film assemblies are either the production cost of using complex techniques like wet spinning or the unsatisfactory results of unevenly distributed and lumping nanoparticles within the film. The new bubble film technique results in well-aligned and controlled-density nanowire and carbon nanotubes (CNTs) films over large areas. These findings could finally open the door to affordable and reliable large-scale assembly of nanostructures.

Posted: May 31st, 2007