Monday, November 28, 2011
Very Speedy Fish
Graphene Foam Sensors Cheaply Detect Trace Particles in Air Ten Times Better Than Current Tech
Using Graphene Foam to Detect Gases RPI
Nanotechnology as a discipline is bleeding-edge cool, but so often we hear more about its amazing potential than its practical application. So it’s always refreshing to catch wind of a story like this: Researchers at Rensselaer Polytechnic Institute in New York have developed and demonstrated a small, relatively inexpensive, and reusable sensor made of graphene foam that far outperforms commercial gas sensors on the market today and could lead to better explosives detectors and environmental sensors in the very near future.
The new sensor dispenses with a lot of the limitations that have been holding back sensors in this space. In the last several years, many strides have been made in the science of manipulating nanostructures to be excellent detectors of very fine trace elements of chemicals on the air. But these sensors, while great in theory, are impractical in actual service.
Current sensor designs are complex, often relying on an individual nanostructure that must be carefully manipulated and even more carefully analyzed. They are often not reusable and must be deployed at specific temperatures or pressures, making a handheld sensor device unreliable, very expensive, and impossible to use repeatedly.
Enter graphene foam. The new postage-stamp-sized sensor developed at RPI involves growing graphene--one-atom-thick layers of carbon--on a structure of nickel foam. Removing that nickel foam leaves behind a structure of foam-like graphene with unique electrical properties that can be tuned to the task of sensing.
When exposed to air, particles adsorb to the foam’s surface. And each of these particles affects the graphene foam in a different way, slightly modifying its electrical resistance. Run a current through it, and a measurement of the change in resistance tells a you what’s sticking to the foam. Moreover, by running a roughy 100-milliampere current through the foam the RPI team found they could cause the particles to desorb--that is, they unattached themselves from the sensor, cleansing it so it can be used again and again.
Tweaked to detect ammonia (a key ingredient in homemade explosive ammonium nitrate--think: fertilizer bombs), the graphene foam sensor managed to detect the offending particle at just 1,000 parts-per-million in just five-to-10 minutes--making it ten times more effective than the best detectors on the market today. A second demo involving nitrogen dioxide (another trace element given off by explosives as they degrade) showed nearly identical results--effective at 100 parts-per-million, or ten times better than current commercial sensors.
Given that graphene foam is fairly easy to handle and manipulate given its larger size and room-temperature-ready performance, that’s pretty remarkable. It also drastically lowers the barrier to a practical handheld devices for atmospheric sensing. See more straight from the source in the vid below.
Smart-Phone App Warns Pedestrians of Oncoming Cars
WalkSafe beeps and vibrates a phone when its owner is in the path of a fast-moving vehicle.
Researchers at Dartmouth College and the University of Bologna in Italy have developed an Android app that uses the camera on a smart phone to detect oncoming traffic.
The app relies on machine-learning and image-recognition algorithms to identify the fronts and backs of vehicles, and takes into account varying light conditions, phone tilt, and blur. When WalkSafe detects a car approaching at 30 miles per hour or faster, it vibrates the phone and makes a sound to alert the distracted user.
Andrew Campbell, professor of computer science at Dartmouth and head of the Smartphone Sensing Group, says the app also exploits phone APIs to only run the vehicle-detection algorithm during active calls, saving the phone's battery.
Using a Nexus One phone, the researchers show that WalkSafe could reliably detect oncoming cars as far as 50 meters away from pedestrians (see the video above). They now plan to speed up the recognition algorithm to improve the app.
Now all we need is system to alert for people who text and walk.
Tiny Magnets Could Clear Diseases from the Blood
Blood cleaner: A microscope image shows one of the carbon-encapsulated nanomagnets used in the study.
Inge Herrmann
Inge Herrmann
BIOMEDICINE
Tiny Magnets Could Clear Diseases from the Blood
Researchers make magnetic nanoparticles that can latch on to harmful molecules and purge them from the blood.
Researchers in Zurich, Switzerland, are developing nanomagnets that could someday strip potentially harmful substances from the blood. The technology might treat people suffering from drug intoxication, bloodstream infections, and certain cancers.
The project involves magnetized nanoparticles coated with carbon and studded with antibodies specific to the molecules the researchers want to purge from the blood: inflammatory proteins such as interleukins, or harmful metals like lead, for example. The researchers can filter out the unwanted compounds by adding the nanomagnets to blood and then running the blood through a dialysis machine or similar device.
"The nanomagnets capture the target substances, and right before the nanoparticles would be recirculated, the magnetic separator accumulates the toxin-loaded nanomagnets in a reservoir and keeps them separated from the recirculating blood," explains Inge Herrmann, a chemical engineer at the University of Zurich who is leading the work.
According to a study published in the journal Nephrology Dialysis and Transplantation in February 2011, the researchers removed 75 per cent of digoxin. This heart drug can prove fatal if given too high a dose in a single pass through a blood-filtration device. After an hour and a half of cleansing, the nanomagnets had removed 90 per cent of the digoxin.
One big caveat is that the researchers must demonstrate that the particles aren't toxic to the body and won't interfere with the blood's ability to clot. But early results are promising. In a 2011 paper in Nanomedicine, Herrmann's group showed that the nanomagnets did not damage cells or promote clotting—two critical safety milestones.
At the annual meeting of the American Society of Anesthesiologists in October, Herrmann presented data showing that the nanomagnets are partially taken up by monocytes and macrophages, two forms of immune cells. That's a necessary proof of principle for any future application of the technology in fighting severe infections.
Herrmann and her colleagues are now studying the technology in rats with sepsis—a severe bloodstream infection marked by the massive buildup of damaging immune molecules. Severe sepsis affects approximately a million people in the United States each year.
Jon Dobson, a biomedical engineer at the University of Florida, says detoxification is "an exciting application" of nanotechnology. His group has been using magnetic nanoparticles as remote controls to manipulate cellular activity, such as the differentiation of stem cells. "With chemicals, it can be difficult to switch it off once the process starts. With magnetic technology, you can switch it on and off at will," Dobson says.
The potential uses of the Swiss group's method extend beyond sepsis to other diseases, including blood cancers, Dobson says. For example, it might be possible to design nanomagnets that pair up with circulating leukaemia cells and usher them out of the body, thus reducing the risk of metastasis.
The potential uses of the Swiss group's method extend beyond sepsis to other diseases, including blood cancers, Dobson says. For example, it might be possible to design nanomagnets that pair up with circulating leukaemia cells and usher them out of the body, thus reducing the risk of metastasis.
O. Thompson Mefford, a nanotechnology expert at Clemson University, says the approach has appeal. He notes that the human body is a highly oxidative environment, and iron oxidation weakens the material's magnetic properties. By coating their magnets in carbon, the Swiss group may have devised a way to prevent this corrosion.
Still, he says, the technique's viability remains to be seen: "Having high circulation times, no immune response, and having the magnets not cluster with each other, that's a real challenge."
Closer to a cure for eczema
Scientists have found that a strain of yeast implicated in inflammatory skin conditions, including eczema, can be killed by certain peptides and could potentially provide a new treatment for these debilitating skin conditions. This research is published in the Society for Applied Microbiology’s journal, Letters in Applied Microbiology.20% of children in the UK suffer from atopic eczema and whilst this usually clears up in adolescence, 7% of adults will continue to suffer throughout their lifetime. Furthermore, this type of eczema, characterized by dry, itchy, flaking skin, is increasing in prevalence. Whilst the cause of eczema remains unknown, one known trigger factor is the yeast Malassezia sympodialis.
This strain of yeast is one of the most common skin yeasts in both healthy individuals and those suffering from eczema. The skin barrier is more fragile and often broken in those suffering from such skin conditions, and this allows the yeast to cause infection which then further exacerbates the condition. Scientists at Karolinska Institute in Sweden looked for a way to kill Malassezia sympodialis without harming healthy human cells.
The researchers looked at the effect on the yeast of 21 peptides which had either; cell-penetrating or antimicrobial properties. Cell-penetrating peptides are often investigated as drug delivery vectors and are able to cross the cell membrane, although the exact mechanism for this is unknown. Antimicrobial peptides, on the other hand, are natural antibiotics and kill many different types of microbe including some bacteria, fungi and viruses.
Tina Holm and her colleagues at Stockholm University and Karolinska Institute, added these different peptides types to separate yeast colonies and assessed the toxicity of each peptide type to the yeast. They found that six of the 21 peptides they tested successfully killed the yeast without damaging the membrane of keratinocytes, human skin cells.
Tina commented “Many questions remain to be solved before these peptides can be used in humans. However, the appealing combination of being toxic to the yeast at low concentrations whilst sparing human cells makes them very promising as antifungal agents. We hope that these peptides in the future can be used to ease the symptoms of patients suffering from atopic eczema and significantly increase their quality of life.”
The next step will be to further examine the mechanism(s) used by the peptides to kill yeast cells, in order to develop a potential treatment for eczema and other skin conditions.
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-Health Research on Skin Conditions
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