Fact of the day!
Today’s science fact is about the Texan Horned Lizard.
This lizard deters predators by shooting its own blood into their face. Out of its eyes. Apparently the blood taste......Learn More!
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| In the computer simulation, the composite is cut (far left) and the nanorods begin migration to the cut interface. In the third image, the polymerization from the rods surface and cross-linking initiates, culminating in the newly regrown gel (final image). Credit: University of Pittsburgh |
When a chair leg breaks or a cell phone shatters, either must be repaired or replaced. But what if these materials could be programmed to regenerate-themselves, replenishing the damaged or missing components, and thereby extend their lifetime and reduce the need for costly repairs? That potential is now possible according to researchers at the University of Pittsburgh Swanson School of Engineering, who have developed computational models to design a new polymer gel that would enable complex materials to regenerate themselves.
Principal investigator is Anna C. Balazs, PhD, the Swanson School's Distinguished Robert v. d. Luft Professor of chemical and petroleum engineering, and co-authors are Xin Yong, PhD, postdoctoral associate, who is the article's lead author; Olga Kuksenok, PhD, research associate professor; and Krzysztof Matyjaszewski, PhD, J.C. Warner University Professor of Natural Sciences, department of chemistry at Carnegie Mellon University.
"This is one of the holy grails of materials science," noted Dr. Balazs. "While others have developed materials that can mend small defects, there is no published research regarding systems that can regenerate bulk sections of a severed material. This has a tremendous impact on sustainability because you could potentially extend the lifetime of a material by giving it the ability to regrow when damaged."
The research team was inspired by biological processes in species such as amphibians, which can regenerate severed limbs. This type of tissue regeneration is guided by three critical instruction sets -- initiation, propagation, and termination -- which Dr. Balazs describes as a "beautiful dynamic cascade" of biological events.
"When we looked at the biological processes behind tissue regeneration in amphibians, we considered how we would replicate that dynamic cascade within a synthetic material," Dr. Balazs said. "We needed to develop a system that first would sense the removal of material and initiate regrowth, then propagate that growth until the material reached the desired size and then, self-terminate the process."
"Our biggest challenge was to address the transport issue within a synthetic material," Dr. Balazs said. "Biological organisms have circulatory systems to achieve mass transport of materials like blood cells, nutrients and genetic material. Synthetic materials don't inherently possess such a system, so we needed something that acted like a sensor to initiate and control the process."
The team developed a hybrid material of nanorods embedded in a polymer gel, which is surrounded by a solution containing monomers and cross-linkers (molecules that link one polymer chain to another) in order to replicate the dynamic cascade. When part of the gel is severed, the nanorods near the cut act as sensors and migrate to the new interface. The functionalized chains or "skirts" on one end of these nanorods keeps them localized at the interface and the sites (or "initiators") along the rod's surface trigger a polymerization reaction with the monomer and cross-linkers in the outer solution. Drs. Yong and Kuksenok developed the computational models, and thereby established guidelines to control the process so that the new gel behaves and appears like the gel it replaced, and to terminate the reaction so that the material would not grow out of control.
Drs. Balazs, Kuksenok and Yong also credit Krzysztof Matyjaszewski, who contributed toward the understanding of the chemistry behind the polymerization process. "Our collaboration with Prof. Matyjaszewski was exceptionally valuable in allowing us to accurately account for all the complex chemical reactions involved in the regeneration processes" said Dr. Kuksenok.
"The most beautiful yet challenging part was designing the nanorods to serve multiple roles," Dr. Yong said. "In effect, they provide the perfect vehicle to trigger a synthetic dynamic cascade." The nanorods are approximately ten nanometers in thickness, about 10,000 times smaller than the diameter of a human hair.
In the future, the researchers plan to improve the process and strengthen the bonds between the old and newly formed gels, and for this they were inspired by another nature metaphor, the giant sequoia tree. "One sequoia tree will have a shallow root system, but when they grow in numbers, the root systems intertwine to provide support and contribute to their tremendous growth," Dr. Balazs explains. Similarly, the skirts on the nanorods can provide additional strength to the regenerated material.
The next generation of research would further optimize the process to grow multiple layers, creating more complex materials with multiple functions.
Source: University of Pittsburgh
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| This chart shows star temperatures vs. stellar flux showing various zones including Earth. Credit: Chester Harmon |
Scientists should take the conservative approach when searching for habitable zones where life-sustaining planets might exist, according to James Kasting, Evan Pugh Professor of Geosciences at Penn State, including when building Terrestrial Planet Finders. That conservative approach means looking for planets that have liquid water and solid or liquid surfaces, as opposed to gas giants like Jupiter or Saturn. The habitable zone in a solar system is the area where liquid water, and by extension life, could exist. Defining the habitable zone is key to the search for life sustaining planets in part because the idea of a habitable zone is used in designing the space-based telescopes that scientists would use to find planets where metabolism -- and potentially life -- life might exist.
"It's one of the biggest and oldest questions that science has tried to investigate: is there life off the earth?" Kasting said. "NASA is pursuing the search for life elsewhere in the Solar System, but some of us think that looking for life on planets around other stars may actually be the best way to answer this question."
Recent research by Ravi Kopparapu, a post-doctoral researcher working with Kasting, suggests that the frequency of Earth-like planets in the habitable zones of stars known as M-dwarfs is 0.4 to 0.5. To find four potential Earth-like candidates, scientists would need to survey the habitable zones of about 10 cool stars. This data came from NASA's Kepler Space Telescope, which collected information on transiting exoplanets for almost four years before being partially disabled. Previous estimates put this frequency at 0.1, which would have forced scientists using planet finders to survey more stars, searching farther away from our Solar System.
An even more recent estimate of the frequency of Earth-like planets was announced by Eric Petigura and colleagues at the Kepler Science Conference in early November. They calculated the figure at 0.22 around stars more similar to the Sun. But Kopparapu and Kasting think Petigura and colleagues' estimate could be too high by a factor of two because they used an overly optimistic estimate for the width of the habitable zone. If so, then the old value of 0.1 may be closer to the truth.
The ability of a planet to sustain liquid water is traditionally part of the criteria when searching for life-sustaining planets. While some have argued that subsurface water would be enough to sustain life, testing that hypothesis remotely would be virtually impossible, so the focus for astronomers should remain on surface water, Kopparapu and Kasting note in a special issue of the Proceedings of the National Academies of Science.
"All life that we know of is carbon-based and depends on the presence of liquid water during at least part of its life cycle," Kasting notes in the paper. "Hence, if we see a planet that shows evidence for liquid water, we can immediately think about the possible presence of carbon-based life."
While no federal funding to build a Terrestrial Planet Finder is currently in place, the amount of research related to exoplanets is strengthening. A TPF would allow for the detection of gases -- or lack thereof -- in planets' atmospheres. If, for example, no signs of life are found after searching the habitable zones of 30 stars, that could be a reason for pessimism, said Kasting, who is also part of Penn State's Earth and Environmental Systems Institute.
And, while it may be more appealing to know that there is evidence of life on other planets, learning that there is not would have scientific implications.
"Maybe every planet out there that has the right conditions develops life," Kasting said. "We don't really know the answer to that. But, it could be. If you're an optimist, you think it just takes the right conditions. It happened on Earth, why wouldn't it happen somewhere else?"
It is possible that initial observations of Earth-like exoplanets could give an ambiguous answer, Kasting added. For example, oxygen might be found, but not methane. But even that could open the door to further exploration.
While the pursuit of life in the outer reaches of the sky might seem far-fetched at first glance, Kasting noted that astronomers have talked about it as a second Copernican revolution.
"Did it make any difference when we figured out that the Earth was going around the sun rather than vice versa? If you're just a practical-minded person, it made absolutely no difference to your life because life goes on Earth just the way it did," Kasting said.
"But if you expand your mind a little bit, it helped us figure out our place in the universe -- that we're actually on a little planet going around a rather normal star amongst many other stars in the galaxy, and there are many galaxies out there. It's been one of the most profound changes ever in human thought. We think of TPF as the next step in the Copernican revolution, to figure out if there are other Earths out there and if there is life on those planets."
Source: Penn State
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| Satellite imagery of the ancient Roman city of Apamea reveals that the entire site has been pockmarked with holes dug by looters since the start of the civil war. |
The Romans occupied modern-day Syria, and before them, the Assyrians, Persians and Akkadians built empires there.
The country is home to ancient Paleolithic fossils, some of the earliest evidence of agriculture and one of the largest troves of cuneiform tablets ever discovered.
"It's probably one of the oldest occupied areas of the Earth," said Emma Cunliffe, an archaeology researcher at Durham University in England, who has published a report documenting archaeological damage in Syria. "It's been continuously occupied since before modern man even existed."
Yet hundreds of archaeological sites are imperiled by civil war in Syria; bombing and looting have ravaged some of the richest of these sites; government and rebel forces have occupied ancient castles and bulldozed archaeological mounds created over thousands of years of human occupation. All six of the UNESCO World Heritage Sites in the country have been damaged, Cunliffe said.
Still, some archaeologists are trying to preserve Syria's heritage. They are talking to government and rebel leaders to protect the most important treasures, and have compiled a list of the key archaeological "no strike" sites that should be protected.
"This is the heritage first and foremost of the Syrian people, and then of the whole world," said Andrew Moore, the first vice president of the Archaeological Institute of America. "It's therefore in everybody's interests to do all they can to protect these important monuments."
Littered with heritage
As part of the Fertile Crescent, the land that is now Syria has been occupied for tens of thousands of years.
Syria contains some of the world's most beautiful Roman cities, Apamea and Palmyra, as well as a stunning Crusader-era castle called Krak des Chevaliers. Archaeologists have unearthed tens of thousands of cuneiform tablets in the ancient city of Ebla. The country houses the tombs of several of Mohammed's relatives, and its cities of Aleppo and Damascus have been continuously occupied for thousands of years.
Syria is also littered with thousands of other unstudied archaeological sites.
Historically, people in the region have built mud brick settlements on the ruins of earlier cities. Over thousands of years, a large mound, or tell, forms with layers of each civilization piled atop one another, said Jesse Casana, an archaeologist at the University of Arkansas and the chairman of the American Schools of Oriental Research's Damascus Committee.
Thousands of tells are scattered throughout the country. Most have not been excavated, and even at the most famous digs, archaeologists have barely scratched the surface, Casana said.
Bombing and looting
Bombing has already destroyed some of the most beautiful landmarks in the country. Last year, a 10th-century mosque in the old city of Aleppo was destroyed by bombing, and large parts of the old city, which may be one of the oldest continuously occupied cities in the world, were damaged as well.
But looting is a far bigger problem than direct destruction, Casana said.
Shadowy networks of antiquities smugglers outside of Syria are paying desperate locals to strip archaeological sites of artifacts.
Other evidence suggests that fighters are smuggling artifacts to buy weapons, Cunliffe said.
At the same time, the civil war has drained resources for protecting archaeological sites. Though civil servants do what they can, their efforts are no match for the chaos.
Ebla has been extensively looted and post-civil war satellite imagery has revealed that Apamea, the historic Roman city, has been riddled with holes since the start of the civil war.
"It looks like the surface of the moon," Cunliffe told LiveScience. "In eight months, the looted area exceeded the total excavated area."
Archaeological mounds, meanwhile, serve as attractive outposts for military because of their higher elevation.
"A lot of archaeological sites are being pretty severely damaged by military," Casana told LiveScience. "They build huge bunkers for tanks, or anti-aircraft equipment. They dig huge trenches into them and bulldoze sides of them off."
Protecting future sites
Archaeologists are doing what they can to protect the most famous sites. They have spoken with rebel and government forces about protecting those sites.
And organizations such as Blue Shield have documented damage using satellite imagery and have compiled lists of hundreds of the most valuable sites.
The U.S. government has added those sites, along with places such as hospitals and schools, to its "no strike" list. If the United States does pursue military strikes, hopefully, the potential for damage will be limited, Casana said.
Still, there's no undoing the damage that's already been done. The site that Casana once studied, Tell Qarqur in Western Syria, has been badly damaged.
"They put tanks on my site," Casana said. "I'm sure they're using my excavation trenches as toilets and digging holes in the thing. It's pretty depressing."
Scientists from Melbourne IVF and the Royal Women's hospital helped a woman who had both her ovaries removed get pregnant.
Australian doctors succeeded in helping a woman get pregnant seven years after her ovaries were removed during cancer treatment.
Vali, a woman from Brisbane, Queensland, Australia, asked doctors to preserve some of her ovarian tissue while she was undergoing cancer treatment in case it was possible to graft it back in the future.
"It didn't really hit me until I was ... 24 and I had to make some serious decisions about my healthcare then," she said. "I was really lucky with my doctors. I was able to have this opportunity even though I didn't really know anything about it."
Associate professor Kate Stern, head of fertility preservation at Melbourne IVF, said she consulted with Vali's surgeon and oncologist before attempting the first graft in 2010.
A second graft was done two years later.
The process produced two eggs, which where later fertilized and put back inside Vali's uterus. The 24-year-old cancer survivor and her partner, Dean, are now expecting twins.
Stern said when they began the procedure it was "unlikely" that it would be successful.
"There have been 29 babies born in the world [using this procedure]," he said. "But that's all from tissue that's been grafted back into the ovary or close to the ovary. But still, with that 29 there have been multiple, multiple, multiple attempts."
Stern said there was a big team of people behind the breakthrough.
"It's amazing how everyone is so excited for our patient. We've been doing this for a long time now, so it's taken a while to get to this point."
Australian doctors succeeded in helping a woman get pregnant seven years after her ovaries were removed during cancer treatment.
Vali, a woman from Brisbane, Queensland, Australia, asked doctors to preserve some of her ovarian tissue while she was undergoing cancer treatment in case it was possible to graft it back in the future.
"It didn't really hit me until I was ... 24 and I had to make some serious decisions about my healthcare then," she said. "I was really lucky with my doctors. I was able to have this opportunity even though I didn't really know anything about it."
Associate professor Kate Stern, head of fertility preservation at Melbourne IVF, said she consulted with Vali's surgeon and oncologist before attempting the first graft in 2010.
A second graft was done two years later.
"The
tissue was put back in the front wall of her abdomen, so that means
it's under the skin and the muscle but not inside the abdomen," Stern
said.
"We wanted to see if this might help her get pregnant. Then we gave
her some very gentle hormone stimulation -- not the full-on IVF."
The process produced two eggs, which where later fertilized and put back inside Vali's uterus. The 24-year-old cancer survivor and her partner, Dean, are now expecting twins.
Stern said when they began the procedure it was "unlikely" that it would be successful.
"There have been 29 babies born in the world [using this procedure]," he said. "But that's all from tissue that's been grafted back into the ovary or close to the ovary. But still, with that 29 there have been multiple, multiple, multiple attempts."
Stern said there was a big team of people behind the breakthrough.
"It's amazing how everyone is so excited for our patient. We've been doing this for a long time now, so it's taken a while to get to this point."
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| The hyperspectral camera is mounted under the wing of the airplane used for research. Credit: Fraunhofer IFF |
This look at a grapevine's "inner qualities" is made possible by special software that processes data from a hyperspectral camera, which records images of many adjacent wavelengths. Researchers at the Fraunhofer Institute for Factory Operation and Automation IFF in Magdeburg developed the software and the mathematical models it contains. "Every molecule absorbs light in a very specific wavelength range," explains project manager Prof. Udo Seiffert. "The camera chip we use covers a large area of the relevant wavelength spectrum and, together with appropriate software, is able to scan the biochemical composition of every single recorded pixel precisely." The camera thus delivers an overview of every constituent present in a plant in any significant concentration – a kind of hyperspectral "fingerprint".
A camera delivers an overview of phytoconstituents
The raw data have to be processed appropriately in order to make them usable for clients. "Our data processing is based on mathematical modeling. On the basis of these algorithms, the software recognizes characteristic absorption properties of defined target constituents and filters them out of the raw data," explains Seiffert. Initially, the researchers have to calibrate the software for the particular application so that it "knows" what constituents it should display. To do so, they photograph reference plants with their camera in order to obtain the fingerprint of the constituents. Then, the photographed tops of the plants are sent to a laboratory in order to analyze the concentrations of the constituents that are relevant to the user. Afterward, the laboratory results are entered into the mathematical model together with the hyperspectral fingerprint. The special thing about the software is its ability to correlate information autonomously and to save this knowledge. "Picture it somewhat like learning vocabulary," explains Seiffert. Once the software has learned the correlation, it automatically filters the relevant constituents out of the hyperspectral camera images the next time. Then, a laboratory analysis is no longer needed for other series of measurements.
Looking inside plants creates effective new options for farmers to increase crop yield. For instance, certain metabolites – products of metabolism – provide information on the quality of a plant's nutrition. Farmers can concentrate on cultivating those plants that thrive particularly well under the prevalent climatic conditions, thus enabling them to irrigate their fields less, for instance. Diseases such as fungal infections can also be detected faster thanks to hyperspectral technology. An infested plant activates defense mechanisms before an infection becomes outwardly visible – by dead leaves, stalks or mildew. Theses mechanisms indicate that the plant has detected and is combatting the infection. Previously, such tests required lengthy experiments in greenhouses. Not least, aerial photos can be used to detect sources of infection in a field quickly.
The first series of measurements with the project partner, the Australian Plant Phenomics Facility at the University of Adelaide, have concluded – the results are promising. At present, another use of the camera down under is in the planning stage. A demonstrator of the system's use in greenhouses and laboratories will be on display at Booth E72 in Hall 9 at the BIOTECHNICA in Hannover from October 8 to 10, 2013.