Stories tagged nano
Hey, wait a second...: How could you ever balance one of those on a pencil? Bad science!
Courtesy Matthieu :: giik.net/blogAll y’all up on graphene?
I knew you were. You’re Buzzketeers, the best of the best, the biggest of the brains, the coolest of the cids.
There’s no need to explain graphene to this team (the Lil’ Professors), so it would be totally unnecessary for me to point out that graphene is a fancy material made of a single layer of carbon atoms attached to each other in a honeycomb pattern. It’s about as flat as can be, and when you roll it up you get those little things Science Buzz is so crazy about: carbon nanotubes.
Nanotubes are awesome, and if you click on the link above you can learn about all the awesome things they can do. But graphene…graphene itself may be pretty awesome too. The problem with testing just how awesome graphene is is that it has been exceptionally difficult to a) make a piece of graphene so small that it hasn’t got any of the imperfections that naturally come in large chunks of things, and b) make a device to actually hold the itty bitty graphene well enough to really test the stuff out.
But science has now done those things! Using a tiny sheet of perfect graphene (about 1/100s the width of a human hair) and a really tiny diamond…poker-thing (about 10 billionths of a meter wide), scientists have finally been able to find out exactly how strong graphene is.
So, how strong is it? It’s the strongest! That is to say, the strongest material measured so far. It’s about 200 times the strength of structural steel, or, says Columbia Professor James Hone, “It would take an elephant, balanced on a pencil, to break through a sheet of graphene the thickness of Saran Wrap.”
This statement, of course, wins professor Hone July’s “Awesome explanation, Scientist” award. That’s a good mental image, and it shows a non-scientist like me how strong graphene is.
So…awesome explanation, Scientist! More of that, please!
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The shrinking radio: Courtesy Zettl Research Group, Lawrence Berkeley National Laboratory and University of California at Berkeley.
Courtesy Zettl Research Group
Tiniest radio yet
A fully integrated radio receiver, orders-of-magnitude smaller than any previous radio, was made from a single carbon nanotube (CNT).
When a radio wave of a specific frequency impinges on the nanotube it begins to vibrate vigorously. An electric field applied to the nanotube forces electrons to be emitted from its tip.
This nanotube radio is over 10,000,000,000,000,000,000 times smaller than the Philco vacuum tube radio from the 1930s.
The single nanotube serves, at once, as all major components of a radio: antenna, tuner, amplifier, and demodulator. (Berkely physics research)
See and hear a nano radio
Videos from an electron microscope view of the nanotube radio playing two different songs are linked below.
- Good Vibrations (Quicktime, 8.06 MB)
- Star Wars (Quicktime, 8.68 MB)
Nano structure self assembly
Courtesy Scott Warren and Uli Wiesner, Cornell University
Materials scientists perfect nano assembly of catalytic meshes
Catalysts, because of its shape, can speed up chemical reactions. Platinum is a useful catalyst in fuel cells but because it costs over $2000 an ounce, it needs to be used efficiently. One way to maximize the effectiveness of platinum is to maximize its surface area.
Cornell researchers have developed a method to self-assemble metals into complex configurations with structural details about 100 times smaller than a bacterial cell by guiding metal particles into the desired form using soft polymers. NSF News
How to self-assemble porous nano mesh
To keep nano spheres of platinum from clumping or "globbing" they are coated with an organic material known as a ligand. The innovative use of the ligands allows for the metal nanoparticles to be dissolved in a solution containing long co-polymer chains, or blocks, of molecules linked together to form a predictable pattern. After the spheres have filled in the spaces created by the co-polymer chains, heat is applied until the polymer turns to a carbon scaffold. The scaffold holds the platinum spheres in place until cooled. The carbon is then dissolved away leaving an intricate hexagonal mesh of platinum (see image above).
New surface textures will benefit plasmonics science
These metalic surfaces will also be of interest to scientists working in an area called plasmonics. Plasmonics is the study of interactions among metal surfaces, light, and density waves of electrons, known as plasmons. Improved optics applications, like lasers, displays, and lenses and better transmission of information within microchips will be some benefits.
Are nanomaterials safe?
Nanomaterials & health
Courtesy GiselaGiardino²³Nanomaterials show promise for curing diseases. But, how can we assess the risk of these nanomaterials causing problems within the human organism. Studies in animals are expensive and time consuming. Also, different cell types can respond differently to the same nanomaterial.
A fast screening method could help separate the good from the bad
Stanley Shaw and researchers from the Broad Institute of Harvard and MIT recently tested 50 different nanoparticles--mainly particles used for medical imaging, including mostly iron-based particles, as well as several types of quantum dots. The particles also had various chemical coatings.
The researchers tested each of the nanoparticles in four different types of cells--immune cells from mice, two types of human blood-vessel cells, and human liver cells--and at four different dosages. To create the different combinations, a robotic system similar to that used for drug screening placed the nanoparticles inside tiny wells on a plate containing hundreds of separate wells. Each well contained one cell type. The screening system then detected changes in the cells' metabolism in response to the nanomaterial. Computer software analyzed the data, looking for relationships between the different particles. Technology Review
The new screening tool, described in the Proceedings of the National Academy of Sciences, could help narrow the list of nanomaterials that need to undergo animal testing.
"Paper towel" can clean up oil spills
Researchers at MIT have combined a nanowire mesh with a water-repellant coating that can absorb up to 20 times its weight in oil. The oil absorbed can be recovered and the "paper towel" can be reused many times.
"Made of potassium manganese oxide, the nanowires are stable at high temperatures. As a result, oil within a loaded membrane can be removed by heating above the boiling point of oil. The oil evaporates, and can be condensed back into a liquid. The membrane--and oil--can be used again." MIT News
Last weekend, NIST (the guys who keep track of what time it is) hosted a RoboCup nanosoccer exhibition match, where the playing field was smaller than a grain of rice. Read more about the nanobot soccer match at BotJunkie.
Will wonders never cease?: A hypochondriac surfer...
Courtesy RickydavidIronic, isn’t it? Silver kills werewolves, werewolves hate silver…and yet these ancient enemies are more alike than they ever knew.
As we all know, materials start to get a little crazy when they approach the nano scale. Try as I might to crush bacteria to death with my silverware (beats washing it), silver on the flatware scale is not a very effective antimicrobial material.
When you get down to the nano scale, however, where silver particles are just a few billionths of a meter, it’s no longer like chasing down flagellates with a spoon. Really, nothing is quite like chasing down flagellates with a spoon, but all comparison is lost in the case of nano-silver.
It has been known for years now that nanoparticles of silver are able destroy harmful bacteria. The nanoparticles generate unique chemicals, known as “highly reactive oxygen species,” which inhibit the growth of bacteria. This is great, because we all hate those harmful bacteria. Nano-silver, for instance, is already found in certain fabrics to destroy odor-causing bacteria, and some high-tech washing machines generate tiny particles of silver for essentially the same reason.
Unfortunately, it’s becoming clear that these glittery little assassins may be the enemy of all bacteria, harmful and helpful.
It’s like this: we’d all love werewolves if they just spent their days tearing apart mummies, because mummies are gross and dangerous. But when werewolves start ripping into other more beneficial monsters, like Frankensteins, well, then they tend to lose favor. Frankensteins may be gross, but they have good hearts.
These tiny silver particles, according to researchers at the University of Missouri, have been ripping into Frankensteins. It’s been observed that nano-silver kills off beneficial, benign bacteria, like that used for wastewater treatment. As consumer use of nano-incorporating products increases, so to will the amount of artificial nano particles in the waste stream. Eventually this could kill off vital microbial species in rivers, streams, and lakes, as well as those used in wastewater treatment. There may be indirect consequences as well—for instance, the “sludge” byproduct of wastewater treatment is frequently used as land-application fertilizer. If silver nanoparticles accumulate in high enough levels in this sludge, they could end up seriously damaging the soil we use to grow our food crops.
This isn’t to say that we should necessarily halt our use of nano products, but it’s a reminder of how little we still know about nanotechnology. While we’ve had hundreds of years to learn to learn the ins and outs of deal with werewolves, nanotechnology is still pretty mysterious.
The University of Missouri will soon be launching a second study to determine the levels at which silver nanoparticles become toxic, and to exactly what extent they harm microbes in wastewater.
No needles insulin
Courtesy Aki Hanninen
Using needles is a pain
Injecting insulin with needles must be a pain for those with diabetes. Non-needle insulin delivery like inhalers or skin patches have not made it to market. Insulin via pills have failed because stomach acid destroys the insulin.
Stomach-proof gel hints at jab-free diabetes treatment
A new flexible hydrogel, when formed into 100 nanometer particles, can soak up insulin. The insulin within its cage-like structure is resistant to the biodegrading effects of stomach acid or enzymes. In a non-acid environment (like the intestines), the hydrogel swells and releases its insulin payload. When coated with a wheat-germ protein called agglutinin, the nanoparticles stick to the cells in the upper small intestine and helps the insulin get through the intestinal wall and into the blood stream. Animal trials of the gel are planned to start soon.
Sources:
New Scientist Tech
American Chemical Society (Abstract of paper published in Biomacromolecules)
Popcorn shaped dye particles double cheaper solar cell efficiency
Popcorn-ball design doubles efficiency of dye-sensitized solar cells: A close-up of a single ball, taken with a scanning electron microscope. The 300-nanometer sphere is large enough to scatter light. But its insides are made of tiny grains just 15 nanometers across.
Courtesy University of Washington Dye-sensitized solar cells, which are more flexible, easier to manufacture, and cheaper than existing solar technologies just got even better.
By using particles shaped like popcorn, University of Washington researchers were able to increase solar cell efficiencies from 2.4 up to 6.2 per cent. The porosity of the large balls (300nm) allowed light to penetrate into the layers and bounce around between balls increasing absorption. Each balls surface was made of smaller spheres (15nm) increasing the effective surface area. One gram of this material has a surface area of 1000 square feet.
The research used the pigment zinc oxide, which is of lower efficiency than the commercially used titanium oxide, but easier to work with during experiments. Titanium oxide layers are expected to show similar gains. While titanium oxide cells currently have a record efficiency of 11 percent, the researchers hope that by using the new method they can by far surpass this old record, possibly even surpassing silicon cell efficiencies. Such progress could make silicon cells, used for decades, obsolete, replaced by cheaper, more efficient, flexible cells.
Source; University of Washington News
Graphene potentially 100x better than silicon
Graphene computer chips: The slightly darker purple area is the graphene, and the lighter purple is the substrate material (SiO2/Si).
Courtesy S. Cho and M. S. Fuhrer, University of Maryland Graphene could replace silicon as the material of choice for many applications like high-speed computer chips and biochemical sensors.
Michael Fuhrer in a paper published online in Nature Nanotechnology explains that in graphene, the intrinsic limit to the mobility, a measure of how well a material conducts electricity, is higher than any other known material at room temperature.
If other extrinsic factors that limit mobility in graphene, such as impurities and lattice vibrations in the substrate on which graphene sits, could be eliminated, the intrinsic mobility in graphene would be more than 100 times higher than silicon.
The low resistivity and extremely thin nature of graphene makes it ideal for applications like touch screens, photovoltaic cells, and chemical and biochemical sensors. The research group was led by principal investigator Michael Fuhrer of the University of Maryland's Center for Nanophysics and Advanced Materials and the Maryland NanoCenter.
Better than silver or gold
Fuhrer said the electrical current in graphene is carried by only a few electrons moving much faster than the electrons in a metal like silver.
"Our current samples of graphene are fairly 'dirty' due to some extraneous sources of resistivity,"
"Once we remove that dirt, graphene, at room temperature, should have about 35 percent less resistivity than silver, the lowest resistivity material known at room temperature."
Roadmap for progress
Because graphene is only one atom thick, current samples must sit on a substrate, in this case silicon dioxide. The electron mobility within the graphene is effected by the substrate. Trapped electrical charges in the silicon dioxide (a sort of atomic-scale dirt) and vibrations of the silicon dioxide atoms can also have an effect on the graphene which are stronger than the effect of graphene's own atomic vibrations.
"We believe that this work points out the importance of these extrinsic effects, and creates a roadmap for finding better substrates for future graphene devices in order to reduce the effects of charged impurity scattering and remote interfacial phonon scattering." Fuhrer said.
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