Carbon nanotubes (CNTs) add strength and design flexibility to many materials, from reinforcing adhesives and materials used in electronics to enhancing the design of carbon fiber composites for use in cars and aerospace applications. But there's been increasing evidence that they, along with other nanoscale materials, may pose risks to human health and the environment. In ongoing research efforts to determine just how toxic they actually are, researchers at Texas Tech University have come up with a new method for detecting CNTs in soils.
The university's environmental biologists built an apparatus that can quantify how much CNT is present in a given soil sample. That's not an easy task since they're so small: mean outer diameters of 13nm to 16nm are common in multi-walled tubes. The apparatus was developed as part of the researchers' ongoing work in locating CNTs in biological environments and examining how they to accumulate in soil, plants such as food crops, or other organisms.
Researchers at Texas Tech University have come up with a new method for detecting CNTs in soils, which will help determine their toxicity. CNTs are so small that mean outer diameters of 13nm to 16nm are common in multi-walled tubes, shown here as grains partially smeared on paper (scale in centimeters). (Source: Shaddack/Wikimedia Commons)
The testing apparatus works by exposing soil samples to microwaves, which can reveal even mere trace quantities of CNTs. That's because, in the presence of microwaves, CNTs produce very high quantities of heat, much higher than most materials. The effect is so extreme that, if you put CNTs in your kitchen microwave oven, the carbon will spontaneously ignite. The researchers used this fact to heat samples to different temperatures to determine different concentration levels. The method has also been used to determine the amount of CNT loading in plant samples and earthworms.
The news about CNTs' toxicity is more than a little unwelcome, since graphene, the tubes' constituent substance, is the hardest known substance. When layers of it are rolled up into tubes, the resulting CNTs constitute a fiber that is 100 times stronger than steel and weighs one-sixth as much. That combination, along with qualities such as mechanical strength and electrical and thermal conductivity, makes them highly unusual and ideal building blocks for industrial uses.
Earlier this year, a joint study by the University of Missouri and the US Geological Survey showed CNTs to be toxic to various species of invertebrate aquatic organisms that live in sediment, including mussels, worms, and crustaceans. These researchers note that CNTs, which may contain metals as well as carbon, tend to accumulate in sediment when released into water. Both the metals -- including nickel, chromium, and other metals used in manufacturing that may remain as impurities -- and the carbon in CNTs can reduce growth rates or even kill certain types of marine life. The degree of toxicity varied depending on the type and source of CNT, the species of test organism, whether the materials had been cleaned using acid, and what method was used for dispersing the materials.
Researchers of the joint study say one of the biggest potential contamination risks occurs during the manufacture of carbon composites, but careful waste management and handling procedures can reduce that risk. More information is also needed on what happens when the composites begin to break down.
Great parallel. Burning "stuff" is a quick solution used too many places in the world. When the fire is out, the stuff is gone and out of mind. But what is out of mind oftimes becomes the stuff in the lungs, the bloodstream, the organs and cells.
As for the scented candles, hopefully the proliferation of LED "fake" candles on the store shelves this year lead to fewer scented candles that must be endured. A Christmas wish for 2013 and beyond?
"Burning stuff" is how nature does it. [I've been presented lake sediment data showing prehistoric fire events were quite periodic (every 25-27 years)]
It doesn't go away.
We evolved eating and breathing it. (we didn't evolve eating grains)
Inspired by the hooks a parasitic worm uses to penetrate its host's intestines, the Karp Lab has invented a flexible adhesive patch covered with microneedles that adheres well to wet, soft tissues, but doesn't cause damage when removed.
Engineers at the University of California, San Diego are designing a robotic arm that takes inspiration from the loose, flexible, yet very strong structure of the armored plates on a seahorse's tail.
Researchers at the Missouri University of Science & Technology have designed a new nanoscale material that can transmit light faster than the 186,000 miles per second it usually takes to travel through air.
It has often been said that as California goes, so goes the nation. This spring, the state's wind power is setting energy generation records and solar energy generation is expected to rise sharply during the second half of 2013.
The latest model of Liquid Robotics' Wave Glider autonomous, unmanned marine vehicle (UMV), the SV3, is reportedly the world's first hybrid wave- and solar-power-propelled unmanned ocean robot.
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A quick look into the merger of two powerhouse 3D printing OEMs and the new leader in rapid prototyping solutions, Stratasys. The industrial revolution is now led by 3D printing and engineers are given the opportunity to fully maximize their design capabilities, reduce their time-to-market and functionally test prototypes cheaper, faster and easier. Bruce Bradshaw, Director of Marketing in North America, will explore the large product offering and variety of materials that will help CAD designers articulate their product design with actual, physical prototypes. This broadcast will dive deep into technical information including application specific stories from real world customers and their experiences with 3D printing. 3D Printing is
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