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Taken with a flash, this photo contrasts reflectivity and absorbtion of various materials. On the left is a circle of black paint, in the middle is the new darkest material, and on the right is a disk of carbon. With the flash, it is easy to see how much blacker than black paint the material really is.  (Source: National Geographic)
Specialized nanotubes set the record for the blackest material on Earth

Chalk up another valuable use of carbon nanotubes -- creating the darkest material on Earth.  Last month researchers at Rice College and Rensselaer Polytechnic Institute in New York used the handy carbon molecular structures to set an unusual world record -- the record for the most light-absorbing material known to man.

The key to the technology is atom-thick nanotubes.  The tubes are arranged vertically on the surface, widely-spaced and standing on end, like the bristles of a paint brush.  The key is the spacing.  By widely spacing the tubes, light is able to enter the material, but then ends up trapped within the collection of thin tubes. 

Project leader and Rensselaer physics professor Shawn-Yu Lin explains, "The loosely packed forest of carbon nanotubes, which is full of nanoscale gaps and holes to collect and trap light, is what gives this material its unique properties.  Such a nanotube array not only reflects light weakly, but also absorbs light strongly. These combined features make it an ideal candidate for one day realizing a super black object."

To give an idea of exactly how black the result is, black paint reflects approximately 5 percent of the visible light that strikes it.  The previous darkest material was a nickel-phosphorous compound, which only reflected 0.35 percent of visible light.  The new nanotube compound blows away these previous competitors, reflecting a bare 0.045 percent of the visible light that hits it. This is almost nine times less than the previous record holder and over a hundred times less than black paint.

Scientist Richard Massey, a dark matter expert at the California Institute of Technology in Pasadena calls the material "very clever", but warns the public not to confuse it with dark matter.  He explains that dark matter absorbs no light and somehow behaves as if transparent, allowing all light to pass through it.  He contrasts this with the new material which "absorbs all light without reemitting/reflecting any—hence no light reaches us from it, and it appears dark."

The work was featured in the journal Nano Letters.  The team also applied for a Guinness World Record for the blackest material.

The first possible business application considered by Rice and RPI was solar power.  Despite the recognition, though, the solar industry remains relatively lukewarm to the new material.  While a few companies such as SolFocus contacted the team, others like Marc Cortez, executive vice president of sales and marketing at Soliant Energy were skeptical about the technology.  Mr. Cortez stated doubts about whether the technology could make an impact, stating, "The ultimate challenge will be to take it from the lab into a high-volume manufacturing environment.  It’s only then you’ll know whether or not it will be a 'game-changing' technology."

With the solar power industry not warming up enough to the new technology, a new group has jumped in to court Rice and RPI -- the U.S. Military.   The Military, according to Popular Science, approached the researchers with interest in using the technology.  The Military, which is investigating a number of nanotube applications, expressed hopes for employing the technology to make its B-2 stealth bombers even stealthier.  By using the material, the B-2s would be capable of absorbing even more radar, making them more difficult to spot.  The military is excited about how the new material could revolutionize its stealth efforts, making its arsenal deadlier and more efficient than ever.

Meanwhile, Professor Yu-Lin is quick to remind people of the technology's more peaceful applications such as improving the efficiency of solar panels, which are typically coated in more reflective black paint.  Another valuable application, he believes is using the material to line telescope barrels to provide a darker background to provide less interference with the focused celestial light.

One thing's for sure, whether it be for war or for peace, someone is certain to be interested in a commercial application of this exciting new nanotube material.

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RE: nanos
By KristopherKubicki on 2/23/2008 12:43:01 AM , Rating: 2
You received criticism from others, but I personally feel a need for more research into this too.

At one time, we encouraged asbestos to no end. It was the miracle material. CNTs and buckeyballs are todays miracle materials.

A year ago, I called for awareness into this field. Not because I want CNT development halted, but because I think if we understand the risks before plunging headlong into them, we (the scientific community) can pre-emptively counter the naysayers with logical, clearly defined studies.

I strongly advise anyone involved in the field of CNT research to start the analysis now and do it in an honest and thorough manner.

RE: nanos
By masher2 on 2/23/2008 1:44:42 PM , Rating: 1
> "At one time, we encouraged asbestos to no end."

The asbestos scare is truly one of the more overstated scares in environmental history. The average person has millions of asbestos fibers in their lungs, all from natural sources. Many studies have shown low levels of asbestos exposure generate no increased risk of lung disease.

For asbestos miners who for decades were chronically exposed to asbestos levels millions of times higher, a risk exists. But even here, the risk was small, and almost always confined to patients who had some other aggravating factor (like tobacco smoke).

The asbestos scare has spawned the world's largest gravy train for trial lawyers, amounting to a $100+ billion dollar payout nearly all of which was for cases not actually caused by asbestos exposure.

RE: nanos
By Optimizer on 2/23/2008 9:57:22 PM , Rating: 2
Maybe for chrysotile asbestos but I wouldn't be so quick to dismiss the risks of amphibole asbestos such as tremolite found in Zonolite attic insulation.
How do the risks from exposure to different kinds of asbestos differ?
Though chrysotile (white asbestos) has been used most widely, the greater potency of amphibole (blue and brown) asbestos to cause illness is generally recognised. Hodgson and Darnton in their scientific paper (2000) estimated the risk of mesothelioma and lung cancer by asbestos fibre type for a range of different exposure scenarios [2]. This analysis suggests that on average blue asbestos has a risk about 500 times that of white asbestos for mesothelioma and 10-50 times as high for lung cancer. The equivalent risk ratio for brown asbestos is 100 for mesothelioma and the same as blue (10-50) for lung cancer.

Once asbestos fibres are in your lungs, they are there permanently. Indeed, just because you have asbestos fibres in your lungs, it doesn't mean that you'll develop asbestos related diseases. Also, because it takes at least 10 years and in some cases up to 60 years) after first exposure to asbestos fibres for any asbestos related illness to develop, there's a good chance that you'll die for some other reason first.

Is there a safe level of exposure below which there is no risk?

There is a lack of scientific consensus as to whether there exists a threshold of exposure to asbestos below which a person is at zero risk of developing mesothelioma. However, there is evidence from epidemiological studies of asbestos exposed groups that any threshold for mesothelioma must be at a very low level – and it is fairly widely agreed that if a threshold does exists then it cannot currently be quantified. For practical purposes HSE does not assume that such a threshold exists.

Asbestosis and lung cancer
The situation for lung cancer and asbestosis is uncertain. Arguments for a threshold for lung cancer are based on the notion of the carcinogenic process being an extension of the chronic inflammatory processes producing fibrosis. It is generally recognised that heavy doses of white asbestos are required to produce clinically significant lung fibrosis. However, the situation for blue and brown asbestos is more uncertain and fibrosis has been observed at much lower exposures. This also suggests that if a threshold for lung cancer does exist for blue and brown asbestos it must be at a very low level indeed.

Whatever the statistics say, I am not so quick dismiss it as a low probability risk while looking into the eyes of my 3 year old.

RE: nanos
By masher2 on 2/23/2008 11:33:33 PM , Rating: 2
> "I am not so quick dismiss it as a low probability risk while looking into the eyes of my 3 year old. "

Would you let your family live in Monterey County, California...or any of the other several places around the world where naturally occurring asbestos is in the air, at levels far higher than one would ever receive from ceiling tiles?

Would you feed your child a Happy Meal? The increased risk of cancer from one hamburger a week (due to the higher-fat diet) is much greater than the excess risk of mesothelioma from exposure to the levels of asbestos one would see from any non-occupational exposure.

Asbestos is a risk to occupational workers -- people who are constantly exposed, particularly when the material is being mined or processed, and thus releases large amounts of dust. For the rest of us, the risk is simply vastly overstated.

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