Stories tagged Structure of Matter
Carbon nanotubesCourtesy St StevA new study published in the scientific journal Nature Nanotechnology shows that longer fibers of carbon nanotubes seem to mimic asbestos when injected into the abdomens of mice. This raises new safety concerns for the up-and-coming technology.
When the mice were injected with asbestos and with various sizes of carbon nanotube samples, the researchers discovered that the longer nanotubes acted in the same way as the asbestos, causing inflammation and lesions. Exposure to asbestos is considered the main cause of a cancer known as mesothelioma.
Just like nanotechnology today, asbestos was once considered a wonder material until its cancer-causing effects on the protective covering (mesothelium) of the body’s organs were realized.
Read more here.
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Oil painting by Vincent Van Gogh (Art Institute of Chicago): Did Vincent know his new way of seeing things was made possible by using an ancient medium?Courtesy Mark RyanOil painting, long considered a European invention dating from the 15th Century, appears now to have originated in Asia and from as early as the middle of the 7th Century.
Tests done on a series of wall murals discovered in caves in the Afghan region of Bamiyan show that the paint used is composed of resin and oil probably extracted from poppies or walnuts.
"This is the earliest clear example of oil paintings in the world, although drying oils were already used by ancient Romans and Egyptians, but only as medicines and cosmetics," said Yoko 
Gathering samples for analysis: Yoko Taniguchi and team members collect paint samples from one of the cave murals at Bamiyan.Courtesy National Research Institute for Cultural Properties, Tokyo (Japan), who led a team of scientists from the National Research Institute for Cultural Properties in Tokyo, the Centre of Research and Restoration of the French Museums, and the California-based Getty Conservation Institute.
The caves are located behind the site of the giant Buddha statues destroyed by the Taliban in 2001 because they were deemed “un-Islamic”. The Taliban also damaged the cave walls.
Close-up of Buddhas on muralCourtesy National Research Institute for Cultural Properties, Tokyo (Japan)Many of the cave paintings depict the robed Buddha sitting among mythical creatures, and are thought to have been painted by itinerant artisans traveling along the Silk Road, an ancient trade route linking China and the West.
Pigment layers under the microscopeCourtesy National Research Institute for Cultural Properties, Tokyo (Japan)Samples of the ancient pigment were tested at the European Synchroton Radiation Facility (ESRF) in Grenoble, France. The team used a combination of synchrotron techniques including mass spectrometry and gas chromatography to analyze several paintings from twelve of the caves and also from fragments of the toppled Buddha statues. The paint turned out to be composed of a mix of layered inorganic pigments and organic binders, such as natural resins, gums and protein. The latter indicates the possible use of egg or hide glue. Concentrations of lead carbonates known as lead whites were also detected.
"The use of drying oils in painting clearly shows an understanding of the properties of this material," said Ioanna Kakoulli, a materials archaeologist at the UCLA/Getty Conservation Program in Los Angeles. Although Kakoulli was not directly involved in the analysis, she confirmed it was of some of the earliest identified examples of drying oils used as a binding media in painting.
"Due to political reasons research on paintings in Central Asia is scarce," said team leader Taniguchi. "We were fortunate to get the opportunity from UNESCO, as a part of conservation project for the World Heritage Site Bamiyan, to study these samples."
Results of the study are published in the Journal of Analytical Atomic Spectrometry.
LINKS
ESRF site story
What is a Synchrotron?
NewKerala.com (India) story
Reuters.com story
National Geographic story
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 insulinCourtesy 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)
Taking some of the poison out of wine: Don't worry--the snake died happy.Courtesy niko siSouth African entrepreneur and former pro rugby player, Guy Kebble, has supposedly invented a method of purifying wine that could eliminate some of the negative side effects of drinking. The side effects in question include headaches and nausea, which nobody likes. There’s still no word as to whether the new wine filtering technique will have any affect on some of the other side effects of drinking, like dangerously creative dancing, or telling that dude what you really think of his fauxhawk.
Before we get into the specifics of Guy’s technique, let’s learn a little bit about hangovers.
As we all know, hangovers are primarily the result of an epic scale battle of wills between the mind and the body. Always at war, a night of drinking might be considered a specific “battleground” between the armies of the brain and the body, an opportunity for each faction to make the other do something it knows is a bad idea. The desolation of the morning after, however, has time and time again shown that, in war, no one wins.
Ethyl alcohol is the active component of beer wine and liquor. We drink it, and things get a little goofy. Ethyl alcohol, or ethanol, is not to be confused with methyl alcohol. Methyl alcohol, or methanol, can be distilled from wood, and differs from ethanol by a single carbon atom and a couple of hydrogens. When we drink methanol, however, things get really goofy. Like, we go blind and die.
Aside from the goofy stuff, ethanol is a diuretic—it makes us pee more. Because of all this peeing, we get dehydrated after boozing it up. Dehydration gives us dry mouths and aching heads. Also, being dehydrated can cause or little brains to shrink slightly and pull away from the sides of the skull, which is kind of unsettling.
Along with dehydration, when our body metabolizes alcohol things get a little crazy. Shortly after consuming alcohol, our bodies turn it into acetaldehyde. Acetaldehyde is a flammable, fruity smelling liquid, and it’s found naturally in fruit, coffee, and fresh bread. And it causes hangovers. The acetaldehyde is then converted in the liver to acetic acid, a reaction that redirects glucose (sugar) from our brains, and when our brains don’t get their sugar fix, they get angry. Also, they get tired, weak, moody, and unable to concentrate.
Finally, the presence of other chemicals mixed in with the alcohol, called congeners, can cause trouble. Congeners are products of fermentation, and are sometimes added to drinks to enhance flavor. They also can make us sick.
This is where the South African wine scheme comes in. Most wine, it seems, has sulphites added to it, to help preserve it from spoiling. Some people are intensely allergic to sulphites, but most of us just get headaches from them. But the alternative is drinking spoiled wine. Or no wine at all, if you want to get technical.
Guy Kebble claims to have invented a machine that purifies liquids using “ultra-violet technology,” making it unnecessary—in wine—to add sulphites to kill the little wine-dwelling microbes. And without the sulphites, all that stands in the way of joyful mornings-after are dehydration, acetaldehyde poisoning, and hypoglycemia.
That’s all? This Guy’s going to be rich.
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.
Grand Challenges for Engineering in the 21st Century
Want to know what to do with your life. A diverse committee of experts from around the world, at the request of the U.S. National Science Foundation, identified 14 challenges that, if met, would improve how we live.
Here is their list in no particular order. You can learn more about each challenge by clicking on it.
- Make solar energy economical
- Provide energy from fusion
- Develop carbon sequestration methods
- Manage the nitrogen cycle
- Provide access to clean water
- Restore and improve urban infrastructure
- Advance health informatics
- Engineer better medicines
- Reverse-engineer the brain
- Prevent nuclear terror
- Secure cyberspace
- Enhance virtual reality
- Advance personalized learning
- Engineer the tools of scientific discovery
You can vote for which is most important
The committee decided not to rank the challenges. NAE is offering the public an opportunity to vote on which one they think is most important and to provide comments at the Engineering Challenges website
Nano (not!): Built for the 1958 Brussels World's Fair, this model of a body-centred cubic crystal is similar to the nano crystal created with DNA except it is magnified 165 billion times.Courtesy John Kerno
First step toward three-dimensional catalytic, magnetic, and/or optical nanomaterials
Assembling structures that are 1000 times smaller than a human hair is difficult. One technique that works is known as "self assembly". A random mixture of microscopic parts can be coaxed into assembling spontaneously into a desired structure by attaching appropriate segments of DNA to various parts. Complementary DNA strands want to "pair up". This is how nano structures are assembled in living organisms.
"researchers at the U.S. Department of Energy's Brookhaven National Laboratory have for the first time used DNA to guide the creation of three-dimensional, ordered, crystalline structures of nanoparticles.
Nanomaterials: Golden handshake
The team from Brookhaven and another group from Northwestern University in Evanston, US, both started with tiny spheres of gold around 10 nanometres across, and attached short strands of DNA. By varying the length of the DNA strands, their flexibility,and the types of sticky ends, they are working toward reliably binding them together in particular ways. This is the first step toward building three-dimensional catalytic, magnetic, and/or optical nanomaterials.
Sources:
- "DNA-programmable nanoparticle crystallization" Nature; abstract (Jan 31, 2008)
- New Scientist Tech: source article
- Brookhaven National Laboratory News release from
Types of carbon nanotubesCourtesy Wikimedia CommonsUS researchers announced they have created the "darkest man-made material ever", using sheets of carbon just a single atom thick and rolled into tubes.
The nanotubes possess properties that make them great absorbers of light, and - at the same time – very lousy reflectors of it. And by roughing up the tube’s surface, scientists can adjust the material to make it scatter light even more.
"The periodic nanotube structures make an ideal candidate for creating superdark materials, because it allows one to tailor light absorption by controlling the dimensions and periodicities of nanotubes in the structure," said Dr Pulickel Ajayan, of Rice University in Houston, Texas, who led the team of researchers.
This stuff is so dark Ajayan and his team have entered it in the Guinness Book of World Records.
So what good is superdark material? Will it change your life? Just how dark do your groovy sunglasses really need to be?
Well, a super light-absorber could prove to be very useful in such things as electronics, computer chip technology, solar panels and solar-cells, or telescope optics. Just about anything that collects light or solar energy could benefit.
SOURCE
BBC.com
Houston Chronicle story
I-35 Bridge Collapse: Curious onlookers view the fallen I-35 structure from the 10th Avenue Bridge in Minneapolis.Courtesy Mark RyanThe National Transportation Safety Board (NTSB) is scheduled to make an announcement today regarding the cause of the I-35 bridge collapse in Minneapolis last August.
Fallen I-35 BridgeCourtesy Mark Ryan
A report in the New York Times says investigators have traced the source of the catastrophic failure to a design flaw in the gussets, the common steel plates that connect the angled beams of many US bridges.
Gusset plate visible in the I-35 bridge wreckage.Courtesy Mark Ryan
Sources in the report say the gussets used in the Minneapolis span weren’t structurally sound enough to meet safety margins even in the 1960s. Further repairs and renovations over the ensuing decades added even more weight and stress to the structure causing some of the gussets to snap finally. The flaw, according to the NSTB, has not been found in other existing US bridges.
The final report on the cause of the collapse won’t be released for several months, but today’s news conference should shed some light on the direction investigators are moving.
