Secrets of spider silk unraveled

Scientists claim to have recently made progress towards understanding what's behind the incredible strength of spider silk fibers

When you explore haunted houses or search for sacred artifacts in ancient temples, the cobwebs that you brush out of your way may seem fairly flimsy and inconsequential. For their size, however, spider silk fibers are incredibly strong – enough so that scientists have long been trying to figure out what their secret is, so it can be applied to man-made materials. In a recently-published paper, German scientists claim to have gotten closer to the answer.
"Silk fibers exhibit astonishing mechanical properties. They have an ultimate strength comparable to steel, toughness greater than Kevlar and a density less than cotton or nylon," said senior study author Dr. Frauke Gräter from the Heidelberg Institute for Theoretical Studies. "Because silk fibers continue to outperform their artificial counterparts in terms of toughness, many studies have tried to understand the mechanical characteristics of these extraordinary natural fibers."
It has already been established that spider silk is made up of two types of building blocks, namely soft amorphous and strong crystalline subunit components. Utilizing what they described as "a multi-scale 'bottom-up' computational approach," Gräter's team analyzed the atomic make-up of these components, with an eye towards how they both ultimately contribute to the structure of the fiber. Via computer simulations, they studied the characteristics of individual and coupled subunits, and of complete fibers.
What they discovered was that the silk's elasticity and its ability to distribute mechanical stress comes courtesy of the soft amorphous subunits. Its maximal toughness is a product of the crystalline subunits, and is greatly affected by the way in which they are distributed throughout the fiber. Models incorporating different arrangements of the two types of subunits were then tried out, with Dr. Gräter determining that "a serial arrangement of the crystalline and amorphous subunits in discs outperformed a random or parallel arrangement, suggesting a new structural model for silk."

HyperSolar concentrator could boost solar cell output by 400 percent

HyperSolar intends to produce a thin, flat, clear solar concentrator, that could boost the amount of sunlight reaching solar cells by up to 400 percent
Solar cells are the most expensive part of a solar panel, so it would follow that if panels could produce the same amount of electricity with less cells, then their prices would come down. In order for panels to be able to do so using existing cell technology, however, they would need to get more light to the fewer cells that they still had. Mounting the panels on the end of vertical poles to get them closer to the sun is one possible approach, that might work in the town of Bedrock or on Gilligan’s Island. A better idea, though, is to apply a clear layer of solar concentrators to the surface of a panel – and that’s just what HyperSolar intends to do.
The California company claims that it has just completed the prototype design of “the world’s first thin and flat solar concentrator for direct placement on top of existing solar cells.” Each sheet will contain a matrix of optical concentrators that are capable of collecting sunlight from a variety of angles. Beneath those concentrators will be a “photonics network,” that will channel light from all the collection points on the top to concentrated output points on the bottom. This network will also able to separate the sunlight into different spectrum ranges, so that specific ranges can be sent to specific cells designed to absorb them.
The sheets will also incorporate a photonics thermal management system, that will keep unusable parts of the solar spectrum from reaching the cells. This should keep the cells from overheating, and becoming less efficient.

While HyperSolar predicts that its product will be able to magnify the sun’s rays by 300 to 400 percent, not all cells will necessarily be able to handle that kind of intensity. For that reason, the solar concentrators will come in Low Magnification, High Magnification, and Mix-Mode Magnification models. At the 400 percent level, the company states that a concentrator-equipped panel could use 75 percent less cells than one without.
HyperSolar’s next step will be to produce an actual physical prototype, and see if it works as envisioned. We’ll keep you posted ...

Power Flowers to domesticate wind turbines

Power Flowers could become a common sight in towns and cities

Arguments still rage on, but it's generally accepted that we need to roll out more sustainable power solutions and break away from our reliance on fuels that are going to disappear one day. As advances in solar, wave and wind technologies gather pace, Dutch design house NL Architects has been looking at ways to bring wind turbines closer to where the power they produce is needed, instead of being located on remote hillsides. Inspired by a vertical-axis turbine called Eddy, the team thinks the answer may lie in tree-like creations named Power Flowers.
While most of us will offer strong vocal backing for the construction of wind farms, that can soon change if someone suggests building one nearby. As a result, the tri-blade towers get exiled to the middle of nowhere – or even further away. Instead of having a few high performance giants scattered throughout the land, NL Architects proposes a structure that would bring a few less efficient turbines together and place them closer to the users of the power they generate.

Embarking on the project, the designers asked themselves if it was possible to turn windmills into objects of desire. Bringing a few turbines together on a tree-like structure seemed the way to go, offering not-too-unpleasant aesthetics and power generation in one package. Using the familiar three-bladed turbine for such a creation would lead to similar issues as those currently faced by wind farm builders, so the team opted for the less efficient but not so unwieldy vertical-axis turbine instead.
The NL Architects design team has based its creation on an existing turbine created by Urban Green Energy called Eddy. The makers say that Eddy can be assembled in less than an hour, is safe to use in winds up to 120 mph (193 kph) and will last for at least 20 years. The Power Flowers structure would feature a hollow steel column with branches at the top. These branches would be home to either three or 12 Eddy-like turbines and could be deployed closer to, or even within, urban environments such as parks, streets or roadways.
Although vertical-axis turbines are considered less efficient than their tri-bladed bigger brothers, the Power Flowers design would allow for more of them to be packed into locations otherwise unavailable.
Using figures provided by Eddy's manufacturer, the team reckons that a three-turbine Power Flowers structure would generate over 13,000 kWh of power every year at an average wind speed of 5 meters per second and generate as little as 42.8db of noise at 12 meters per second. Each 12-turbine structure's annual power output for the same average wind speed is calculated at 55,000 kWh.

There are of course unresolved practical and engineering issues to overcome, which would make it very interesting to see if such a structure could actually jump from design software into the real world ... after which, we'd be watching closely for what sort of statistics would actually be produced and how such a thing would be received by the public at large.
Putting all that aside for a moment, would you object to one of these creations appearing outside your bedroom window or in the middle of your local park?

Researchers use bacteria to produce potential gasoline replacement directly from cellulose

Researchers have succeeded in producing isobutanol directly from cellulosic plant matter such as corn stover
With the situation in Libya causing a spike in fuel prices worldwide there's some good biofuel-related news out of the U.S. Department of Energy's BioEnergy Science Center (BESC) that could help to reduce many countries' dependence on oil imports. For the first time, BESC researchers have succeeded in producing isobutanol directly from cellulosic plant matter using bacteria. Being a higher grade of alcohol than ethanol, isobutanol holds particular promise as a gasoline replacement as it can be burned in regular car engines with a heat value similar to gasoline.
Due in large part to its natural defenses to being chemically dismantled, cellulosic biomass like corn stover and switchgrass, which is abundant and cheap, has been much more difficult to utilize than corn or sugar cane. This means that producing biofuel from such biomass involves several steps, which is more costly than a process that combines biomass utilization and the fermentation of sugars to biofuel into a single process.
Building on earlier work at UCLA in creating a synthetic pathway for isobutanol production, the BESC researchers managed to achieve such a single-step process by developing a strain of Clostridium cellulolyticum, a native cellulose-degrading microbe that could synthesize isobutanol directly from cellulose.
"In nature, no microorganisms have been identified that possess all of the characteristics necessary for the ideal consolidated bioprocessing strain, so we knew we had to genetically engineer a strain for this purpose," said Yongchao Li of Oak Ridge National Laboratory.
The research team chose Clostridium cellulolyticum, which was originally isolated from decayed grass, because it has been genetically engineered to improve ethanol production, which has led to additional more detailed research. While some Clostridium species produce butanol and others digest cellulose, none produce isobutanol, an isomer of butanol.
"Unlike ethanol, isobutanol can be blended at any ratio with gasoline and should eliminate the need for dedicated infrastructure in tanks or vehicles," said James Liao, chancellor's professor and vice chair of Chemical and Biomolecular Engineering at the UCLA Henry Samueli School of Engineering and Applied Science and leader of the research team. "Plus, it may be possible to use isobutanol directly in current engines without modification."
Earlier this week, U.S. Energy Secretary Steven Chu visited the BESC to congratulate the research team, saying, "Today's announcement is yet another sign of the rapid progress we are making in developing the next generation of biofuels that can help reduce our oil dependence. This is a perfect example of the promising opportunity we have to create a major new industry – one based on bio-material such as wheat and rice straw, corn stover, lumber wastes, and plants specifically developed for bio-fuel production that require far less fertilizer and other energy inputs."

Laser scribing promises cheaper, more efficient solar panels

A microchannel created using the laser scribing technique
A new manufacturing method that incorporates laser technology may result in thin film solar panels that are less expensive and more efficient than anything presently on the market. Currently, a stylus is used to mechanically etch microchannels into such panels, which electrically connect the individual solar cells and allow them to form an array. Researchers from Indiana's Purdue University, however, are developing a technique in which an ultrafast pulsing laser is used to do the etching. Not only will it hopefully be quicker and cheaper than mechanical "scribing," but it should also produce cleaner, sharper microchannels that offer superior performance.
"The mechanical scribing methods in commercial use do not create high-quality, well-defined channels," said Yung Shin, director of Purdue's Center for Laser-Based Manufacturing. "Although laser scribing has been studied extensively, until now we haven't been able to precisely control lasers to accurately create the microchannels to the exacting specifications required."
Shin's team has addressed the lack of control by using an ultrashort-pulse laser, the individual pulses of which last for only picoseconds, or quadrillionths of a second. The etching process utilizes what is known as "cold ablation," in that the pulse times are so short that the thin film doesn't suffer any heat damage.
"It creates very clean microchannels on the surface of each layer," Shin said. "You can do this at very high speed, meters per second, which is not possible with a mechanical scribe. This is very tricky because the laser must be precisely controlled so that it penetrates only one layer of the thin film at a time, and the layers are extremely thin. You can do that with this kind of laser because you have a very precise control of the depth, to about 10 to 20 nanometers."
The research project will continue for a three year period, by the end of which which the scientists hope to have established the scientific basis for their laser-ablation technique.

New material combines the strength of steel and the moldability of plastic

Jan Schroers and his team have developed novel metal alloys that can be blow molded into virtually any shape
Scientists at Yale University have done what materials scientists have been trying to do for decades – create a material that boasts the look, strength and durability of metal that can be molded into complex shapes as simply and cheaply as plastic. The scientists say the development could have the same impact on society as the development of synthetic plastics last century and they have already used the novel metals to create complex shapes, such as metallic bottles, watch cases, miniature resonators and biomedical implants, that are twice as strong as typical steel and can be molded in less than a minute.
Unlike the crystalline structure found in ordinary metals that makes them strong but also results in them requiring three separate steps for processing (shaping, joining and finishing), the metal alloys recently developed by the Yale team are amorphous metals known as bulk metallic glasses (BMGs), whose randomly arranged atoms and low critical cooling rate allows them to be blow-molded into complex shapes like plastics. This allows the researchers to combine the three traditional time- and energy-intensive metal processing steps into one blow molding process that takes less than a minute.

Although the different metals used to make the alloys, such as zirconium, nickel, titanium and copper, cost about the same as high-end steel, they can be processed as cheaply as plastic, according to Jan Schroers, a materials scientist at Yale that led the team.
The BMGs ability to soften and flow as easily as plastic at low temperatures and low pressures, without crystallizing like regular metal is what allows the material to be shaped with unprecedented ease, versatility and precision, Schroers said. To ensure the ideal temperature for blow molding was maintained, the team shaped the BMGs in a vacuum or in fluid.
"The trick is to avoid friction typically present in other forming techniques," Schroers said. "Blow molding completely eliminates friction, allowing us to create any number of complicated shapes, down to the nanoscale."

Schroers and his team have already fabricated a wide variety of shapes and devices using the new processing technique, including miniature resonators for microelectromechanical systems (MEMs) and gyroscopes, but they say that is just the beginning.

"This could enable a whole new paradigm for shaping metals," Schroers said. "The superior properties of BMGs relative to plastics and typical metals, combined with the ease, economy and precision of blow molding, have the potential to impact society just as much as the development of synthetic plastics and their associated processing methods have in the last century."

The new processing technique developed by the Yale researchers is described online in the current issue of Materials Today.

Self-healing elastic polymers developed with the help of a tree

The healing process demonstrated in the caoutchouc tree-inspired elastomer
When the caoutchouc tree is damaged, liquid latex containing capsules of the protein hevein escapes from inside of it. Those capsules rupture, releasing the hevein, which links the latex particles together and ultimately closes up the wound. The whole bursting/sealing-microcapsules thing is obviously a pretty good idea, as it has been put to use in human technology such as self-healing concrete, electronics, paint and aircraft epoxy resin. Now, German researchers have copied the caoutchouc tree's modus operandi to create a self-sealing elastic polymer.
Scientists from the Fraunhofer Institute for Environmental, Safety and Energy Technology loaded microcapsules with the adhesive polyisobutylene, then put those capsules into synthetic caoutchouc sap elastomers. The idea was that when pressure was put on the elastomers to the point of cracking, the capsules would rupture and mix with the elastomers' polymer chains, thus sealing the cracks.
As it turned out, the capsules didn't cooperate. When the polyisobutylene was added in an uncapsulized form, however, a self-healing effect did occur – the elastomers' tension expansion was restored by 40 percent after a 24-hour healing period.
The scientists further copied the caoutchouc tree, by charging the elastomer with ions. In the case of the tree, the hevein proteins link up with one another (and in the process, with the latex) via ionic bonding. By charging the synthetic elastomer, a similar effect could be achieved with the polyisobutylene.
Fraunhofer will have a self-healing muffler made from the experimental material on display at the Hannover Fair from April 4th to 8th. A self-healing biorenewable polymer is also being developed at Iowa State University.

Human muscle tissue could be grown from sea creatures' whiskers

Academics from the University of Manchester have developed a process of creating working human muscle tissue from sea squirts
Academics from the University of Manchester have developed a process of creating working human muscle tissue from sea squirts. The research holds promise for the engineering of muscles, ligaments and nerves from cellulose which is usually found in plants and is the main component of paper and plant based textiles such as cotton and linen. The creation of muscle from scratch along with the ability to repair existing muscle has the potential to improve the lives of millions of people around the world.
Tunicates, commonly known as sea squirts, grow on rocks and man made structures along coastal waters. They are small rounded or cylindrical animals with a hollow body and an outer shell of cellulose – long chains of sugars joined together. The researchers extract this cellulose in the form of nanowhiskers just 10 nanometers wide (one nanometer is one billionth of a meter) These are thinner than a human hair and smaller than muscle cells. Once aligned and parallel to each other, the nanowhiskers influence the behavior of skeletal muscle cells causing rapid muscle cell alignment and fusion. Alignment is important as it gives muscle tissue its strength and stiffness.
Cellulose is a renewable resource, the method of extraction fast and simple and due to its unique properties. It is already being used for a number of different medical applications including wound dressings and in other commercial applications as an adhesive and binder but this is the first time it has been used for creating muscle tissue.

Researchers develop first molecular piston capable of self-assembly

Scientists have created a nanoscale piston that is capable of self-assembly
Just like a regular-sized device requires a regular-sized motor to operate, a nanodevice likewise requires a molecular-scale motor. In some cases, that motor takes the form of a piston, and building a piston that's just a few nanometers long ... well, it's pretty hard. It can and has been done, but it's an extremely fiddly process. Now, scientists from France's Centre National de la Recherche Scientifique (CNRS) and the Université de Bordeaux, along with colleagues in China, have developed a molecular piston that is capable of assembling itself.
The CNRS/U Bordeaux piston consists of a slender rod-shaped molecule, around which is wrapped a helix-shaped molecule, that slides along the length of the rod. Both molecules are made from organic compounds, which were synthesized specifically for the project.
Previously with such pistons, a nanoscale ring would have to be manually placed around the rod. In this case, the helicoidal molecule was engineered to spontaneously wind itself around the rod, while still staying flexible enough to maintain a decent range of movement.
The helix moves along the rod in response to the acidity of the piston's environment. If the acidity is increased, the helix is drawn toward one end of the rod, while if it's decreased, the helix moves toward the other end.
So, what uses could such a tiny piston be put to? The researchers believe that if several of the nanodevices were joined end-to-end, they could function as a type of simplified artificial muscle tissue, capable of contracting on demand. Also, a surface covered with the pistons could switch between acting as an electrical insulator or conductor, while a larger rod with several helices could be used to create a polymer with adjustable stiffness ... and those are just a few suggestions.
The research, which was led by CNRS' Ivan Huc, was recently published in the journal Science.

Banana peels can be used to purify water

Research published in the journal of the American Chemical Society claims that mashed up peel can remove heavy metals from river water

The skin of a banana has been used to great comic effects in numerous slapstick routines for many years. It's also good for the skin and is a traditional cure for warts. You can polish shoes and silver with it. You can make wine with it and it's even been known to find itself being dried, wrapped in paper and smoked. Now, research published in the journal of the American Chemical Society claims that mashed up peel can remove heavy metals from river water.
Heavy metals can end up in the waterways of the world as a result of industrial or agricultural processes and have been linked to a variety of health problems, ranging from nausea and vomiting to lung, kidney and brain damage. While there are numerous purification methods are already employed to try and keep the nasties at bay, many involve significant cost and can carry their own toxic risks.
Adding to other work which has shown the benefits of using coconut fibers and peanut shells, Gustavo Castro and colleagues from Brazil's Instituto de Biociências de Botucatu at the Universidade Estadual Paulista have found that minced banana peel could quickly remove lead and copper from river water and is at least as effective, and in some cases even better than, existing methods.
The team found that the banana skin water treatment apparatus can be used up to 11 times without losing its cleansing properties. The use of banana skins is seen as very attractive for water purification because of low cost and the fact that no chemical modification is necessary for the process to work.
On the face of it, this seems to be a very promising use for an otherwise discarded waste product. Unfortunately, the university didn't get back to us when we inquired about what happens to the minced banana skin at the end of the process.
More detailed information is available in the research paper entitled Banana Peel Applied to the Solid Phase Extraction of Copper and Lead from River Water: Preconcentration of Metal Ions with a Fruit Waste, which has been published in the American Chemical Society's journal Industrial & Engineering Chemistry Research.