Friday, October 15, 2010

RESEARCH SUGGESTS VOLCANOES NIXED NEANDERTHALS

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New research suggests that climate change following massive volcanic eruptions drove Neanderthals to extinction and cleared the way for modern humans to thrive in Europe and Asia.

The research, led by Liubov Vitaliena Golovanova and Vladimir Borisovich Doronichev of the ANO Laboratory of Prehistory in St. Petersburg, Russia, is reported in the October issue of Current Anthropology.

"[W]e offer the hypothesis that the Neanderthal demise occurred abruptly (on a geological time-scale) … after the most powerful volcanic activity in western Eurasia during the period of Neanderthal evolutionary history," the researchers write. "[T]his catastrophe not only drastically destroyed the ecological niches of Neanderthal populations but also caused their mass physical depopulation."

Evidence for the catastrophe comes from Mezmaiskaya cave in the Caucasus Mountains of southern Russia, a site rich in Neanderthal bones and artifacts. Recent excavations of the cave revealed two distinct layers of volcanic ash that coincide with large-scale volcanic events that occurred around 40,000 years ago, the researchers say.

Geological layers containing the ashes also hold evidence of an abrupt and potentially devastating climate change. Sediment samples from the two layers reveal greatly reduced pollen concentrations compared to surrounding layers. That's an indication of a dramatic shift to a cooler and dryer climate, the researchers say. Further, the second of the two eruptions seems to mark the end of Neanderthal presence at Mezmaiskaya. Numerous Neanderthal bones, stone tools, and the bones of prey animals have been found in the geological layers below the second ash deposit, but none are found above it.

The ash layers correspond chronologically to what is known as the Campanian Ignimbrite super-eruption which occurred around 40,000 years ago in modern day Italy, and a smaller eruption thought to have occurred around the same time in the Caucasus Mountains. The researchers argue that these eruptions caused a "volcanic winter" as ash clouds obscured the sun's rays, possibly for years. The climatic shift devastated the region's ecosystems, "possibly resulting in the mass death of hominins and prey animals and the severe alteration of foraging zones."

Anthropologists have long puzzled over the disappearance of the Neanderthals and the apparently concurrent rise of modern humans. Was there some sort of advantage that helped early modern humans out-compete their doomed cousins? This research suggests that advantage may have been simple geographic location.

"Early moderns initially occupied the more southern parts of western Eurasia and Africa and thus avoided much of the direct impact of the … eruptions," the researchers write. And while advances in hunting techniques and social structure clearly aided the survival of modern humans as they moved north, they "may have further benefited from the Neanderthal population vacuum in Europe, allowing wider colonization and the establishment of strong source populations in northern Eurasia."

While the researchers stress that more data from other areas in Eurasia are needed to fully test the volcanic hypothesis, they believe the Mezmaiskaya cave offers "important supporting evidence" for the idea of a volcanic extinction.

University of Chicago Press

OLDEST EVIDENCE OF DINOSAURS FOUND IN POLISH FOOTPRINTS

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The oldest evidence of the dinosaur lineage—fossilized tracks—is described in Proceedings of the Royal Society B. Just one or two million years after the massive Permian-Triassic extinction, an animal smaller than a house cat walked across fine mud in what is now Poland. This fossilized trackway places the very closest relatives of dinosaurs on Earth about 250 million years ago—5 to 9 million years earlier than previously described fossilized skeletal material has indicated. The paper also described the 246-million-year-old Sphingopus footprints, the oldest evidence of a bipedal and large-bodied dinosaur.

"We see the closest dinosaur cousins immediately after the worst mass extinction," says Stephen Brusatte, a graduate student affiliated with the Division of Paleontology at the American Museum of Natural History. "The biggest crisis in the history of life also created one of the greatest opportunities in the history of life by emptying the landscape and making it possible for dinosaurs to evolve."

The new paper analyzes three sets of footprints from three different sites in the Holy Cross Mountains of central Poland. The sites, all quarries within a 25-mile radius of each other, are windows into three ecosystems because they represent different times periods. The Stryczowice trackway is the oldest at 250 million years. The Baranów trackway is the most recent at 246 million years of age while the Wióry trackway is sandwiched in time between the others.

Because footprints are only an imprint of a small part of the skeleton, identification of trackmakers is often tricky. Luckily, dinosaurs have a very distinctive gait, especially when compared to their diapsid relatives (the evolutionary group that includes birds, reptiles, and extinct lineages) like crocodiles and lizards. While lizards and crocodiles have a splayed walking style, dinosaurs place their two feet closer together. The footprints at all three Polish sites show this feature as well as indisputable dinosaur-like features, including three prominent central toes and reduced outer two toes, a parallel alignment of these three digits (a bunched foot), and a straight back edge of footprints, additional evidence of a dinosaur-like simple hinged ankle.
Because all of these features are seen in footprints at the oldest site, Brusatte and colleagues conclude that the Stryczowice prints—which are only a few centimeters in length—are the oldest evidence of the dinosaur lineage.

These dinosaurs, though, are considered "stem dinosaurs," or the immediate relatives of dinosaurs not part of the slightly more derived clade that technically defines dinosaurs. Also, this animal did walk on all four limbs, an abnormal posture for early dinosaurs and their close relatives, although it appears that its forelimbs were already being reduced to more dinosaur-like proportions since the footprints overstep handprints.

The Baranów and Wióry trackways show changes early in the evolutionary history of dinosaurs. Wióry at 248 million years ago shows slight diversification in the types of tracks, but all tracks remain quadrupedal. Footprints from Baranów at 246 million years ago, however, may be the earliest evidence of moderately large-bodied and bipedal true dinosaurs. These tracks, which are called Sphingopus, are 15 centimeters long.

"Poland is a new frontier for understanding the earliest evolution of dinosaurs," says Grzegorz Niedźwiedzki of the University of Warsaw and the Polish Academy of Sciences, who led the project and has been excavating footprints from the three sites for nearly a decade. "It used to be that most of the important fossils were from Argentina or the southwestern U.S., but in Poland we have several sites that yield footprints and bones from the oldest dinosaurs and their closest cousins, stretching throughout the entire Triassic Period."

Finally, although the dinosaur group emerged soon after the Permian extinction, dinosaur-like tracks are rare in the footprint assemblages, representing only 2 percent of the prints discovered as opposed to 40 percent for crocodile-like archosaurs. Dinosaurs became more abundant tens of millions of years later.

"For the first 20 million years of dinosaur history, dinosaurs and their closest relatives were living in the shadow of their much more diverse, successful, and abundant crocodile-like cousins," says Brusatte. "The oldest dinosaurs were small and rare."

(Photo: AMNH)

American Museum of Natural History

NEW TYPE OF LIQUID CRYSTAL PROMISES TO IMPROVE PERFORMANCE OF DIGITAL DISPLAYS

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Chemists at Vanderbilt University have created a new class of liquid crystals with unique electrical properties that could improve the performance of digital displays used on everything from digital watches to flat panel televisions.

The achievement, which is the result of more than five years of effort, is described by Professor of Chemistry Piotr Kaszynski and graduate student Bryan Ringstrand in a pair of articles published online on Sept. 24 and Sept. 28 in the Journal of Materials Chemistry.

"We have created liquid crystals with an unprecedented electric dipole, more than twice that of existing liquid crystals," says Kaszynski.

Electric dipoles are created in molecules by the separation of positive and negative charges. The stronger the charges and the greater the distance between them, the larger the electric dipole they produce.

In liquid crystals, the electric dipole is associated with the threshold voltage: the minimum voltage at which the liquid crystal operates. Higher dipoles allow lower threshold voltages. In addition, the dipole is a key factor in how fast liquid crystals can switch between bright and dark states. At a given voltage, liquid crystals with higher dipoles switch faster than those with lower dipoles.

Vanderbilt has applied for a patent on the new class of materials. Some of the companies that manufacture liquid crystals for commercial applications have expressed interest and are currently evaluating it.

"Our liquid crystals have basic properties that make them suitable for practical applications, but they must be tested for durability, lifetime and similar characteristics before they can be used in commercial products," Kaszynski says.

If it passes commercial testing, the new class of liquid crystals will be added to the complex molecular mixtures that are used in liquid crystal displays. These blends combine different types of liquid crystals and other additives that are used to fine-tune their characteristics, including viscosity, temperature range, optical properties, electrical properties and chemical stability. There are dozens of different designs for liquid crystal displays and each requires a slightly different blend.

The newly discovered liquid crystals are not only important commercially but they are also important scientifically.

Since 1888 when they were discovered, scientists have discovered more than 100,000 natural and synthetic compounds that have a liquid crystal state. They have determined that one of the prerequisites for such a state is that the molecule must be shaped like either a rod or a disc. A second requirement is that it must contain both rigid and flexible parts. It takes a delicate balance of two opposing factors or forces to produce a material halfway between a crystal and a liquid. However, there is still a great deal about this unusual state that scientists do not yet understand.

For example, scientists are still trying to determine the effect that a liquid crystal's electric dipole has on the temperature at which it becomes an ordinary liquid. The current consensus has been that increasing the strength of the dipole typically raises this transition temperature. The way in which the new type of liquid crystals are synthesized allowed Kaszynski and Ringstrand to test this theory by creating pairs of liquid crystals with the same geometry but different electric dipoles and measuring their transition temperatures. They found that subtle structural differences have a much greater effect on the transition temperature than do variations in the strength of the electric dipole.

What distinguishes the new class of liquid crystals is its "zwitterionic" structure. Zwitterions are chemical compounds that have a total net electrical charge of zero but contain positively and negatively charged groups. The newly developed liquid crystals contain a zwitterion made up of a negatively charged inorganic portion and a positively charged organic portion. Kaszynski first got the idea of making zwitterionic liquid crystals nearly 17 years ago when he first arrived at Vanderbilt. However, a critical piece of chemistry required to do so was missing. It wasn't until 2002 when German chemists discovered the chemical procedure that made it possible for the Vanderbilt researchers to succeed in this effort.

(Photo: Kaszynski lab)

Vanderbilt University

A TRACKING DEVICE THAT FITS ON THE HEAD OF A PIN

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Optical gyroscopes, also known as rotation sensors, are widely used as a navigational tool in vehicles from ships to airplanes, measuring the rotation rates of a vehicle on three axes to evaluate its exact position and orientation. Prof. Koby Scheuer of Tel Aviv University's School of Physical Engineering is now scaling down this crucial sensing technology for use in smartphones, medical equipment and more futuristic technologies.

Working in collaboration with Israel's Department of Defense, Prof. Scheuer and his team of researchers have developed nano-sized optical gyroscopes that can fit on the head of a pin — and, more usefully, on an average-sized computer chip — without compromising the device's sensitivity. These gyroscopes will have the ability to pick up smaller rotation rates, delivering higher accuracy while maintaining smaller dimensions, he says. The research was recently described in the journal Optics Express.

"Conventional gyroscopes look like a box, and weigh two or three pounds," Prof. Scheuer explains. "This is fine for an airplane, but if you're trying to fit a gyroscope onto a smaller piece of technology, such as a cellphone, the accuracy will be severely limited."

At the core of the new device are extremely small semi-conductor lasers. As the devices start to rotate, the properties of the light produced by the lasers changes, including the light's intensity and wavelength. Rotation rates can be determined by measuring these differences.

These lasers are a few tens-of-micrometers in diameter, as compared to the conventional gyroscope, which measures about 6 to 8 inches, says Prof. Scheuer. The device itself, when finished, will look like a small computer chip. Measuring a millimeter by a millimeter (0.04 inches by 0.04 inches), about the size of a grain of sand, the device can be built onto a larger chip that also contains other necessary electronics.

Prof. Scheuer and his team of researchers are currently working on lab demonstrators of the device, which he predicts will be ready for testing in a few years' time.

When available, the nano-gyroscopes will improve technologies that we use every day. When you rotate an iPhone, for example, the screen adjusts itself accordingly. A nano-gyroscope would improve the performance of this feature and be sensitive to smaller changes in position, says Prof. Scheuer. And that's not all. Nano-gyroscopes integrated into common cellphones could provide a tracking function beyond the capabilities of existing GPS systems. "If you find yourself in a place without reception, you would be able to track your exact position without the GPS signal," he says.

There are benefits to medical science as well. Right now, small capsules that contain cameras pass through the body during some diagnostic procedures, but to know where the capsule is within a patient, doctors must track its signal from the outside. With the addition of a nano-gyroscope, explains Prof. Scheuer, the capsule would have a built-in navigation system, which would provide the ability to move the capsule to more specific and precise locations within the body.

(Photo: TAU)

Tel Aviv University

BLIND INVENTORS REVOLUTIONISE COMPUTER ACCESS

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For many blind people, computers are inaccessible. It can cost upwards of $1000 to purchase "screen reader" software, but two blind computer programmers have solved this problem.

Queensland University of Technology (QUT) graduate James Teh and business partner Michael Curran developed a free, open-source program, called NVDA (NonVisual Desktop Access), which provides a synthetic voice to read the words on a computer screen as the cursor moves over them.

The invention won the blind duo accolades in the grand final program of the ABC's iconic New Inventors, which aired on September 23. They took home the "Les* is More" award, for an invention that "might make a real difference to people's lives or the environment."

"A sighted person takes for granted that they can sit down at any computer and use it," Mr Teh said.

"We really are in the information age - everything is online these days. So access to computers for the blind and vision impaired is incredibly important, which is why we wanted our software to be free."

Mr Teh, who majored in software engineering at QUT, said blind students typically didn't have the funds to purchase screen reader technology, at the time in their life when they most needed it. Now NVDA could be downloaded on to anyone's personal computer free of charge.

"It can also be copied to a USB stick, which can be used on any PC at school or university, with no installation required," he said.

Mr Teh knows firsthand the obstacles that blind students face. Studying a Bachelor of Information Technology, many teaching materials involved visual diagrams. His studies were made a lot easier by QUT teachers including computer science lecturer Malcolm Corney, who prepared detailed descriptions of diagrams prior to lectures.

"Sometimes he would sit with me for up to an hour explaining visual materials," said Mr Teh.

Mr Teh and Mr Curran have drawn on their own experience as blind computer users to develop a product which has some unique and innovative features. For example, as the mouse moves up and down the screen, a small beeping sound becomes higher and lower in pitch to let you know where the cursor is located.

NVDA has been translated into 27 languages, thanks to volunteer translators.

To date, there have been over 50,000 downloads. With the number of blind and low vision Australians expected to double to 600,000 in ten years' time (according to Vision Australia), NVDA has the potential to impact a significant number of lives.

"After our initial appearance on the New Inventors in March, we have definitely had more organisations and users interested in our product," Mr Teh said.

"It was amazing to think we were selected from the five finalists to win. We are very happy, proud and honoured."

Mr Teh and Mr Curran have been working on the project since 2006. They worked on their product without remuneration for two years. When Mozilla offered some funding in 2008, Mr Teh was able to quit his day job and work full-time developing NVDA.

Mr Teh and Mr Curran have plenty of future plans, including touch screen options for the blind and vision impaired. While keen to maintain the independence and integrity of their products, the pair's continued success may depend on the availability of further funding.

NVDA can be downloaded from http://www.nvda-project.org/

(Photo: QUT)

Queensland University of Technology

FIRST-OF-ITS-KIND STUDY FINDS ALARMING INCREASE IN FLOW OF WATER INTO OCEANS

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Freshwater is flowing into Earth's oceans in greater amounts every year, a team of researchers has found, thanks to more frequent and extreme storms linked to global warming. All told, 18 percent more water fed into the world's oceans from rivers and melting polar ice sheets in 2006 than in 1994, with an average annual rise of 1.5 percent.

"That might not sound like much – 1.5 percent a year – but after a few decades, it's huge," said Jay Famiglietti, UC Irvine Earth system science professor and principal investigator on the study, which will be published this week in Proceedings of the National Academy of Sciences. He noted that while freshwater is essential to humans and ecosystems, the rain is falling in all the wrong places, for all the wrong reasons.

"In general, more water is good," Famiglietti said. "But here's the problem: Not everybody is getting more rainfall, and those who are may not need it. What we're seeing is exactly what the Intergovernmental Panel on Climate Change predicted – that precipitation is increasing in the tropics and the Arctic Circle with heavier, more punishing storms. Meanwhile, hundreds of millions of people live in semiarid regions, and those are drying up."

In essence, he said, the evaporation and precipitation cycle taught in grade school is accelerating dangerously because of greenhouse gas-fueled higher temperatures, triggering monsoons and hurricanes. Hotter weather above the oceans causes freshwater to evaporate faster, which leads to thicker clouds unleashing more powerful storms over land. The rainfall then travels via rivers to the sea in ever-larger amounts, and the cycle begins again.

The pioneering study, which is ongoing, employs NASA and other world-scale satellite observations rather than computer models to track total water volume each month flowing from the continents into the oceans.

"Many scientists and models have suggested that if the water cycle is intensifying because of climate change, then we should be seeing increasing river flow. Unfortunately, there is no global discharge measurement network, so we have not been able to tell," wrote Famiglietti and lead author Tajdarul Syed of the Indian School of Mines, formerly of UCI.

"This paper uses satellite records of sea level rise, precipitation and evaporation to put together a unique 13-year record – the longest and first of its kind. The trends were all the same: increased evaporation from the ocean that led to increased precipitation on land and more flow back into the ocean."

The researchers cautioned that although they had analyzed more than a decade of data, it was still a relatively short time frame. Natural ups and downs that appear in climate data make detecting long-term trends challenging. Further study is needed, they said, and is under way.

(Photo: Daniel A. Anderson / University Communications)

UC Irvine Earth

A LINK BETWEEN AIR TRAVEL AND DEATHS ON THE GROUND

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The atmosphere is full of natural and man-made chemicals, including emissions from fuel combustion and byproducts of living organisms. Many of these chemicals combine in the atmosphere to form tiny solid and liquid particles known as “fine particulate matter” that are 2.5 micrometers or smaller (the average human hair is about 70 micrometers in diameter, by comparison). While it’s not clear whether all of these particles may be harmful, some are; the danger to humans comes when they are inhaled and trapped in the lungs, where they can then enter the bloodstream.

In 2004, the World Health Organization estimated that about one million deaths per year are caused by air pollution, and several epidemiological studies have linked air pollution to the development of cardiovascular and respiratory illnesses, including lung cancer. Those studies tracked thousands of adults over many years to measure their exposure to air pollution while monitoring their health. Once the data were statistically analyzed to correct for other risk factors like smoking, the results indicated that increased exposure to fine particulate matter caused by air pollution is linked to health problems like chronic bronchitis and decreased lung function, as well as premature death.

Aviation emissions contribute to this health problem, according to a new study that suggests that airplanes flying at a cruise altitude of around 35,000 feet emit pollutants that contribute to about 8,000 deaths per year globally. The research, reported online this month in the journal Environmental Science and Technology, provides the first estimate of premature deaths attributable to aircraft emissions at cruise altitudes. Aircraft emit nitrogen oxides (NOx) and sulfur oxides (SOx), which react with gases already existing in the atmosphere to form harmful fine particulate matter.

Current worldwide regulations target aircraft emissions only up to 3,000 feet. That’s because regulators have assumed that anything emitted above 3,000 feet would be deposited into a part of the atmosphere that has significantly smoother air, meaning pollutants wouldn’t be affected by turbulent air that could mix them toward the ground. Thus, even though 90 percent of aircraft fuel is burned at cruise altitudes, only those pollutants that are emitted during takeoff and landing are regulated by measuring emissions during tests of newly manufactured engines in simulated takeoff and landing conditions.

“Anything above that [altitude] really hasn’t been regulated, and the goal of this research was to determine whether that was really justified,” says lead author Steven Barrett, the Charles Stark Draper Assistant Professor of Aeronautics and Astronautics in MIT’s Department of Aeronautics and Astronautics.

To study the effects of cruise emissions, Barrett used a computer model that combined data about plane trajectories, the amount of fuel burned during flights and the estimated emissions from those flights. He combined that with a global atmospheric model that accounts for air-circulation patterns in different parts of the globe and the effect of emissions to determine where aviation emissions might cause an increase in fine particulate matter. He then used data related to population density and risk of disease in different parts of the world to determine how the change in particulate matter over certain regions might affect people on the ground — specifically, whether the air pollutants would lead to an increased risk of death.

Analysis of these data revealed that aircraft pollution above North America and Europe — where air travel is heaviest — adversely impacts air quality in India and China. That is, even though the amount of fuel burned by aircraft over India and China accounts for only 10 percent of the estimated total amount of fuel burned by aircraft across the globe, the two countries incur nearly half — about 3,500 — of the annual deaths related to aircraft cruise emissions. The analysis also revealed that although every country in the Northern Hemisphere experienced some number of fatalities related to these emissions, almost none of the countries in the Southern Hemisphere had fatalities.

That’s because the majority of air traffic occurs in the Northern Hemisphere, where planes emit pollutants at altitudes where high-speed winds flowing eastward, such as the jet stream, spread emissions to other continents, according to the study. Part of the reason for the high percentage of premature deaths in India and China is that these regions are densely populated and also have high concentrations of ammonia in their atmosphere as a result of farming. This ammonia reacts with oxidized NOx and SOx to create fine particulate matter that people inhale on the ground. Although agriculture is abundant in Europe and North America, the ammonia levels aren’t as elevated above those regions.

Funded by the UK Research Councils with help from the U.S. Department of Transportation, the study recommends that cruise emissions be “explicitly considered” by international policymakers who regulate aviation engines and fuels. Steve Lott, a spokesman for the International Air Transport Association, a trade group that represents 230 airlines, says that aviation is “a small part of a big problem,” particularly when compared to other transportation sources of emissions, such as those caused by shipping, which a 2007 study linked to 60,000 premature deaths per year.

Lourdes Maurice, the chief scientific and technical adviser for environment at the Federal Aviation Administration, says that if the agency can confirm Barrett’s findings through additional research, then it will work with the Environmental Protection Agency and the International Civil Aviation Organization to consider appropriate regulatory action. The FAA will continue to fund research to address uncertainties highlighted by Barrett’s work, she adds.

Barrett concedes that there are many uncertainties, including how accurately the model reflects how air travels vertically from high altitudes to low altitudes. To address this, he is collaborating with researchers at Harvard to study an isotope of the element beryllium that is produced naturally at high altitudes and attaches to atmospheric particles that eventually reach the ground through air or rain. Researchers have a general idea of how much beryllium is concentrated in the atmosphere, and Barrett and his colleagues are currently analyzing ground measurements of the element to quantify the extent to which his model “gets vertical transport right.”

(Photo: Christine Daniloff)

MIT

RESEARCHERS DISCOVER HOW BONE MARROW STEM CELLS INJECTED INTO SKELETAL MUSCLE REVERSE HEART FAILURE

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A growth-factor chain of action that prompts bone marrow stem cells to repair cardiac tissue and reverse heart failure has been identified by researchers at the University at Buffalo's Center for Research in Cardiovascular Medicine.

Earlier research from this group showed for the first time that injecting mesenchymal (bone marrow) stem cells into skeletal muscle in an animal model increased two-fold the production of myocytes, a type of heart muscle cell.

The current findings provide insight into how the injected stem cells may rejuvenate the host tissue. Results of the discovery of this distinct heart repair action appear online as an article-in-press in the American Journal of Physiology-Heart Circulation Physiology at http://www.ncbi.nlm.nih.gov/pubmed/20852053

"By thoroughly understanding the interplay of stem cells and host tissue, and characterizing stem-cell-derived growth factors," says Techung Lee, PhD, senior author on both papers, "it is possible to assemble a cocktail of these factors and use it for tissue repair, much like the use of insulin for diabetes patients."

Lee is associate professor of biochemistry and biomedical engineering in the UB School of Medicine and Biomedical Sciences and the School of Engineering and Applied Sciences, respectively.

Bone marrow mesenchymal stem cells [MSCs] possess an impressive ability to produce a plethora of growth factors, most of which remain to be characterized, Lee says.

"These growth factors appear to account for most of the observed therapeutic benefits in preclinical and clinical studies. Using skeletal muscle as a depot for the injected MSCs, we found that the MSC-derived growth factors activate production of host muscle tissue-derived growth factors."

The heart disease death rate has dropped significantly in the last three decades due to better treatments, resulting in large numbers of people living with heart failure. However, heart transplantation is the only therapy currently available to reverse the continual decline in heart function, and donor hearts are scarce.

Lee notes that current clinical trials of myocardial stem cell therapy require surgery, injecting the cells directly into the heart or into the heart muscle, invasive methods that can result in harmful scar tissue, arrhythmia, calcification or small vessel blockages. Lee's research group found that only 1-to-2 percent of MSCs infused into the myocardium actually grafted into the heart, and there was no evidence that they differentiated into heart muscle cells.

"For these reasons, and because patients with heart failure are not good surgical risks, it made sense to explore a non-invasive cell delivery approach," Lee notes.

Lee's group has shown that the instructive signal that generates the repair of cardiac tissue appears to come from at least a group of MSC-derived factors belonging to the IL-6 type cytokine family. Cytokines are small proteins made by the cells that act on other cells to stimulate or inhibit their function.

"These IL-6 type cytokines typically activate their cell/tissue targets through two specific proteins, known as JAK and STAT3, a cytosolic and a nuclear protein, respectively," explains Lee. "These cytokines then instruct the host cell to produce another panel of growth factors.

"The combined effects of the growth factors from injected stem cells and growth factors produced by host tissues cause tissue repair and achieve healing. Being able to use the factors for therapy rather than stem cells will make therapy to repair hearts much easier," he says.

(Photo: U. Buffalo)

University at Buffalo

MIMICKING NATURE, WATER-BASED ARTIFICIAL LEAF PRODUCES ELECTRICITY

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A team led by a North Carolina State University researcher has shown that water-gel-based solar devices – “artificial leaves” – can act like solar cells to produce electricity. The findings prove the concept for making solar cells that more closely mimic nature. They also have the potential to be less expensive and more environmentally friendly than the current standard-bearer: silicon-based solar cells.

The bendable devices are composed of water-based gel infused with light-sensitive molecules – the researchers used plant chlorophyll in one of the experiments – coupled with electrodes coated by carbon materials, such as carbon nanotubes or graphite. The light-sensitive molecules get “excited” by the sun’s rays to produce electricity, similar to plant molecules that get excited to synthesize sugars in order to grow, says NC State’s Dr. Orlin Velev, Invista Professor of Chemical and Biomolecular Engineering and the lead author of a paper published online in the Journal of Materials Chemistry describing this new generation of solar cells.

Velev says that the research team hopes to “learn how to mimic the materials by which nature harnesses solar energy.” Although synthetic light-sensitive molecules can be used, Velev says naturally derived products – like chlorophyll – are also easily integrated in these devices because of their water-gel matrix.

Now that they’ve proven the concept, Velev says the researchers will work to fine-tune the water-based photovoltaic devices, making them even more like real leaves.

“The next step is to mimic the self-regenerating mechanisms found in plants,” Velev says. “The other challenge is to change the water-based gel and light-sensitive molecules to improve the efficiency of the solar cells.”

Velev even imagines a future where roofs could be covered with soft sheets of similar electricity-generating artificial-leaf solar cells.

“We do not want to overpromise at this stage, as the devices are still of relatively low efficiency and there is a long way to go before this can become a practical technology,” Velev says. “However, we believe that the concept of biologically inspired ‘soft’ devices for generating electricity may in the future provide an alternative for the present-day solid-state technologies.”

North Carolina State University

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