Giant fire-bellied toad's brain brims with powerful germ-fighters

Frog and toad skins already are renowned as cornucopias of hundreds of germ-fighting substances. Now a new report in ACS's Journal of Proteome Research reveals that the toad brains also may contain an abundance of antibacterial and antiviral substances that could inspire a new generation of medicines.

Ren Lai and colleagues point out that scientists know little about the germ-fighting proteins in amphibian brains, despite many studies showing that amphibians synthesize and secrete a remarkably diverse array of antimicrobial substances in their skin. So they decided to begin filling that knowledge gap by analyzing brains from the Giant Fire-Bellied Toad and the Small-webbed Bell Toad.

They discovered 79 different antimicrobial peptides, the components of proteins, including 59 that were totally new to science. The diversity of the peptides "is, to our knowledge, the most extreme yet described for any animal brains," they noted. Some of the peptides showed strong antimicrobial activity, crippling or killing strains of staph bacteria, E. coli, and the fungus that causes yeast infections in humans. These promising findings suggest that the toad brains might be a valuable source for developing new antibacterial and antiviral drugs.

Provided by American Chemical Society (news : web)

Toward a 'green grid' for delivering solar and wind-based electricity

After years of neglect, scientists and policy makers are focusing more attention on developing technologies needed to make the so-called "green grid" possible, according to an article in ACS' Chemical Reviews. That's the much-needed future electrical grid, an interconnected network for delivering solar and wind-based electricity from suppliers to consumers.

Zhenguo (Gary) Yang and colleagues point out that concerns over the use of coal, oil, and other fuels that contribute to global warming and are in limited supply, have spurred interest in generating electrical energy from clean, renewable resources such as solar and wind power. But solar and wind are not constant and reliable sources of power, since wind power fluctuates from moment to moment and solar power is generated only in the daytime.

This situation poses a significant challenge for electrical grid operators because other power plants need to compensate for this variability and the U.S. power grid currently has little energy storage capability. To enable a significant level of penetration and effective use of renewable energy sources amid growing energy demands, electrical grids of the future will need a low-cost, efficient way to integrate and store this electrical energy, the scientists note.

The scientists analyzed the conclusions of more than 300 scientific studies and identified several technologies that can be used for energy storage for the green grid. These include high-tech batteries now in development that can efficiently store electricity in the form of chemicals and reversible release it on demand. Among the promising technologies are so-called redox flow and sodium-ion batteries, which could provide a low cost, high efficiency way to store energy.

In addition to the United States, several other countries such as China and countries in Europe are planning to increase research activities related to energy storage and development. "The growing interests as well as worldwide research and development activities suggest a bright outlook for developing stationary energy storage technologies for the future electric grid," the article concludes.

Provided by American Chemical Society (news : web)

Ceramic coatings may protect jet engines from volcanic ash

Last year's $2 billion shutdown of European airspace following a volcanic eruption in Iceland alerted everyone to the danger that ash clouds can pose to aircraft engines.

Now, researchers have discovered that a new class of ceramic coatings could offer jet engines special protection against volcanic ash damage in the future.

For a study published online in the Early View edition of the journal Advanced Materials, the researchers tested two coatings that were originally developed to keep airborne sand from damaging jet engines, and found that the coatings also resist damage caused by ash deposits.

"Of course, it's best for jets to avoid ash in the first place," said Nitin Padture, College of Engineering Distinguished Professor at the Ohio State University, who led the study. "That's not always possible. We determined that these coatings could offer sufficient protection against small amounts of ash ingested by the engine over time."

However, large amounts of ash can temporarily jam a jet engine and cause it to stall, he explained. These coatings would not be useful in those extreme circumstances.

Temperatures inside an engine reach up to 2,500 degrees Fahrenheit, and ceramic thermal-barrier coatings insulate metallic engine parts from that heat. The ingested ash melts onto the coating and penetrates the coating. Upon cooling, the molten ash forms a brittle glass that flakes off, taking the coating with it.

It's a familiar story to Padture, who previously invented a new coating composition to prevent similar engine damage caused by sand.

Like sand, ash is made mostly of silica. When the Icelandic volcano Eyjafjallajökull erupted in April 2010, it billowed clouds of silicate ash.

"Ash poses a threat very similar to sand, but ash composition varies widely depending on the type of volcano. After what happened in Iceland, we wanted to see how ash interacted with our new thermal barrier coating, and whether the underlying damage mechanisms were any different," he said.

Doctoral students Julie Drexler and Andrew Gledhill took samples of the ceramic coatings on pieces of metal, and coated them with ash from the Eyjafjallajökull eruption. Then they heated the samples in a furnace to simulate the high temperatures created in a jet engine.

They experimented with a typical jet engine coating and two sand-resistant coatings. One was Padture's formula, containing zirconia and alumina, and the other was a commercially available new formula based on gadolinium zirconate.

In that test, the ash badly damaged the typical coating, while coatings made of Padture's formula and the gadolinium zirconate formula retained their overall structure.

Looking at cross-sections of the samples, the researchers saw why: molten ash had penetrated through the pores of the typical ceramic coating all the way to its base. But in the other two, the molten ash barely penetrated.

Drexler explained why the pores are important.

"Pores give the coating its strain tolerance," she said. "They make room for the coating to expand and contract as the engine heats up while flying, and as it cools after landing. When all the pores are plugged with ash, the coating can't adjust to the temperature anymore, and it breaks off."

On the sand-resistant coatings, the ash filled the pores only near the surface. Chemical analysis revealed that the ash reacted with the alumina in the first coating to produce a thin layer of the mineral anorthite below the surface, while on the gadolinium zirconate it produced a layer of the mineral apatite.

"The chemical reaction arrests the penetration of the ash into the coatings," Gledhill said. "The unaffected pores allow the coating to expand and contract."

Now, the researchers are repeating their experiment with a new setup. They are heating samples over and over with a powerful blowtorch, and letting them cool in between to more closely simulate engine conditions.

Both sand-resistant coatings are more expensive than the typical coating, but the researchers think that the benefits outweigh the cost.

"This study's not going to solve all the problems of ash clouds and jet engines, but we are making progress, and we've learned a lot about the physics of the situation," Padture said.

But that's not all they learned.

"We also learned how to pronounce 'Eyjafjallajökull.'"

Provided by The Ohio State University (news : web)

Anti-aging hormone Klotho inhibits renal fibrosis, cancer growth

A natural hormone known to inhibit aging can also protect kidneys against renal fibrosis, UT Southwestern Medical Center researchers have demonstrated.

Scientists led by Dr. Makoto Kuro-o, associate professor of pathology, showed in mice that the anti-aging hormone Klotho suppressed both renal fibrosis – a common complication of chronic kidney disease – and the spread of cancer. The findings are available online in the Journal of Biological Chemistry.

More than 26 million people in the U.S. are affected by chronic kidney disease. Researchers say Klotho also helps patients with acute injury of the kidney that obstructs urine outflow or causes a drop in blood flow to the kidney. Nearly half of the patients in hospital intensive care units have some form of kidney injury due to drugs, surgery, bleeding or dehydration, said Dr. Kuro-o, the study's senior author who discovered Klotho more than a decade ago.

"Within a few days after injury, renal function can be completely gone," he said. "We show that Klotho injection in a drip infusion could be effective not only as an initial treatment for acute kidney injury, but also to prevent its progression into chronic kidney disease. This offers real hope for patients with renal disease."

The UT Southwestern researchers focused on mesenchymal cells: multipotent cells that can differentiate into a variety of cell types. These are essential for development and growth, but when the cells are out of balance, they can morph into a pathological form that causes fibrosis (toughening of the tissue layers) and metastasis in cancer cells, said Dr. Kuro-o.

Scientists involved in this study also found that Klotho prevents cancer migration and metastasis. In the study, they blocked a ureter to cause renal fibrosis or introduced human cancer cells in laboratory mice. Secreted Klotho was effective in blocking three signaling pathways – TGF-?1, Wnt and IGF-1 – that can cause tissue fibrosis or cancer metastasis.

The researchers reported for the first time that Klotho binds to the cells' transforming growth factor receptor and inhibits signaling required for epithelial-to-mesenchymal transition (EMT), a "master switch" that causes cells to morph into a more pliable form. EMT cancer cells can squeeze into surrounding tissue and eventually into the bloodstream, leading to metastatic spreading of cancer.

"This is further evidence that Klotho is an understudied tumor-suppressor and really quite important because it's secreted and flows through the body," said Dr. David Boothman, professor of radiation oncology and pharmacology, associate director for translational research and an author of the study. "It could be a major surveillance mechanism for blocking tumor formation and progression."

Provided by UT Southwestern Medical Center (news : web)

Computer modeling used to study protein involved with cancer, aging and chronic disease

A new biophysical and biochemical study may lead to better understanding of how structural flexibility controls the interaction of a protein that is closely involved with cancer, aging and other chronic diseases -- thereby facilitating future development of better therapeutic strategies, according to a Kansas State University biochemist.

Jianhan Chen, an assistant professor of biochemistry, was one of the researchers on a collaborative project that took a combined computational and experimental approach to understand how protein p21 functions as a versatile regulator of cell division. Their latest findings, "Intrinsic disorder mediates the diverse regulatory functions of the Cdk inhibitor p21," were published in a recent edition of Nature Chemical Biology.

The study used computer simulation to rationalize results from biochemical and biophysical experiments, and provided further insights that would guide future investigations, Chen said. In this case, the focus is human protein p21 and its ability to function as an inhibitor of normal cell growth.

The protein has been shown to be an intrinsically disordered protein. This means it lacks a well-defined three-dimensional structure, characteristics that, until roughly a decade ago, were thought to be necessary for the protein to function.

"For a long time it was believed that proteins must fold to function and it was hard to imagine how an unfolded protein could play a role in crucial cellular areas," Chen said. "What researchers before me found was that by lacking a stable structure, this actually turned out to be really, really important to how these proteins function."

Along with being an intrinsically disordered protein, p21 is a versatile cyclin-dependent kinase, or Cdk, inhibitor -- meaning it adapts to and inhibits a range of Cdk-cyclin complexes that regulate eukaryote cell division. It also has been connected to cancer and aging. For example, Chen said p21 is a principal trans-activation target of the p53 tumor suppressor protein and contributes to p53-dependent tumor suppression.

"This protein is extremely challenging to study. It's highly dynamic and it's heterogeneous," Chen said. Because of this, mechanistic studies of intrinsically disordered proteins like p21 have been limited. Experiment alone is not sufficient and computer modeling is necessary to provide important missing details, he said. A tight integration of both could lead to a precise understanding of how structural flexibility influences function of p21 and other intrinsically disordered proteins.

"For me this is one of the most interesting IDPs," Chen said. "I'm a theorist and I want to use this system to understand the principles of how this type of proteins can perform their functions. Even though they are disordered, they are not random; there is no chaos. They still have some type of residual structures and certain features which allow function to be controlled in a precise way, and I want to understand the underlying mechanism of how this occurs."

Chen is continuing work with p21 and other small proteins that regulate cell cycles.

Provided by Kansas State University (news : web)

Physicists create clouds of impenetrable gases that bounce off each other

When one cloud of gas meets another, they normally pass right through each other. But now, MIT physicists have created clouds of ultracold gases that bounce off each other like bowling balls, even though they are a million times thinner than air -- the first time that such impenetrable gases have been observed.

While this experiment involved clouds of lithium atoms, cooled to near absolute zero, the findings could also help explain the behavior of similar systems such as neutron stars, high-temperature superconductors, and quark-gluon plasma, the hot soup of elementary particles that formed immediately after the Big Bang. A paper describing the work will appear in the April 14 issue of Nature.

The researchers, led by MIT assistant professor of physics Martin Zwierlein, carried out their experiment with an isotope of lithium that belongs to a class of particles called fermions. All building blocks of matter -- electrons, protons, neutrons and quarks -- are fermions.

Different states of fermionic matter are distinguished by their mobility. For example, electrons can be mobile, as in a metal; immobile, as in an insulator; or flow without resistance, as in a superconductor. However, for many types of material, including high-temperature superconductors, it is not known what circumstances induce fermions to form a given state of matter. This is especially true of materials with strongly interacting fermions, meaning they are more likely to collide with each other (also called scattering).

In this study, the researchers set out to model strongly interacting systems, using lithium gas atoms to stand in for electrons. By tuning the lithium atoms' energy states with a magnetic field, they made the atoms interact with each other as strongly as the laws of nature allow, meaning that they scatter every time they encounter another atom.

To eliminate any effects of heat energy, the researchers cooled the gas to about 50 billionths of one Kelvin, close to absolute zero (-273 degrees Celsius). They used magnetic forces to separate the gas into two clouds, labeled "spin up" and "spin down, then made the clouds collide in a trap formed by laser light. Instead of passing through each other, as gases would normally do, the clouds repelled in dramatic fashion.

"When we saw that these ultra dilute puffs of gas bounce off each other, we were completely amazed," says graduate student Ariel Sommer, lead author of the Nature paper.

The gas clouds did eventually diffuse into each other, but in several cases it took an entire second or more -- an extremely long time for events occurring at microscopic scales.

The research, conducted at the MIT-Harvard Center for Ultracold Atoms, is part of a program aimed at using ultracold atoms as easily controllable model systems to study the properties of complex materials, such as high-temperature superconductors and novel magnetic materials that have applications in data storage and improving energy efficiency.

In future work, the researchers plan to confine the lithium gases to two-dimensions, which will allow them to simulate the two-dimensional state in which electrons exist in high-temperature superconductors.

Their work can also be used to model the behavior of other strongly interacting systems, such as high-density neutron stars, which are only a few tens of kilometers in diameter but more massive than our sun.

Another substance that interacts as strongly as the atoms in the ultracold lithium gas clouds created at MIT is quark-gluon plasma, which existed at the universe's formation and has been recreated in particle colliders by colliding atomic nuclei at energies corresponding to a trillion degrees.

Story Source:

The above story is reprinted (with editorial adaptations ) from materials provided by Massachusetts Institute of Technology. The original article was written by Anne Trafton.

Journal Reference:

Ariel Sommer, Mark Ku, Giacomo Roati, Martin W. Zwierlein. Universal spin transport in a strongly interacting Fermi gas. Nature, 2011; 472 (7342): 201 DOI: 10.1038/nature09989

Controlled production of nanometric drops

When a drop falls on a lotus flower it remains on the surface without wetting it. This is due, firstly, to the chemical components of the leaves of this plant, which are hydrophobic and therefore repel water, and, secondly, to the nanostructure of the surface, which augments the repellent effect. Taking these nanostructural properties as a starting point, researchers from the Faculty of Physics at the University of Barcelona have carried out a study -- the results of which have been published in the journal Nature Materials - in which they demonstrate the physical conditions required for the controlled production of drops between the micro- and nanoscales.

The study details the different physical conditions needed to destabilize a fluid and create droplets according to the wetting properties of the surface it is in contact with. Ignasi Pagonabarraga, a lecturer with the Department of Fundamental Physics and one of the authors of the study, explains that "the interaction of the fluid with the surface can be used to control the size of the drops and the time they take to form. Although there are other methods for creating micrometric droplets, the affinity of liquids to solid surfaces creates a more versatile environment for the production and control of drops down to the nanoscale."

According to Aurora Hernández-Machado, a lecturer with the UB's Department of Structure and Constituents of Matter and co-author of the study, "miniaturization in liquids is important in increasing efficiency and optimizing the rate of consumption of substances such as pharmaceutical products, cosmetics and ink, which would enable us to lower the cost of processes associated with the production and control of these products. In addition, the physical model, which we could define as a microfluidic dispenser for various substances, allows us to overcome the limitations traditionally associated with drop formation processes and to create submicrometre-scale droplets."

One of the fields to which this type of process is most readily applicable is the development of lab-on-a-chip (LOC) devices, which integrate a range of laboratory analysis functions into a miniaturized chip format and need only very small volumes of liquid to perform the analyses. The dynamics involved in the formation of submicrometre-scale drops have various technological applications in other fields, for example in controlled drug administration or in the creation of emulsions such as those used in certain types of cosmetic products formed by micro-droplets of substances with specific properties within another fluid. Other applications include ink distribution in printers.

In physical terms, the drops are formed due to instability in the fluid. The study describes a wetting-based destabilization mechanism of forced microfilaments that affects adherence to difference surfaces. The researchers have been able to establish the balance of forces that determines the drop emission mechanism, which involves the capillarity of the fluid, the viscous friction of the solid surface and gravity. This balance and the size of the liquid filaments determine the size of the drops emitted, which in some cases are nanometric. It has also been observed that the emission of drops depends to a great extent on the static wetting angle, that is, the angle that the drop makes with the contact surface. The greater this angle the higher the degree of hydrophobia of the surface in question.

In the experiments carried out for the study, focusing on water in air, the team of researchers has demonstrated the operation of the microfluidic model and created drops at the micrometre scale, but the model is also capable of producing nanometric droplets. Tests have been carried out using a range of supports from hydrophilic surfaces to superhydrophobic substrates, and the authors show how wetting can be used to pinpoint the wetting-controlled emission point. By varying the chemical and nanostructural properties of the surface in question, it is possible to alter the wetting angle and control the drop formation dynamics.

Story Source:

The above story is reprinted (with editorial adaptations) from materials provided by Universidad de Barcelona.

Journal Reference:

R. Ledesma-Aguilar, R. Nistal, A. Hernández-Machado, I. Pagonabarraga. Controlled drop emission by wetting properties in driven liquid filaments. Nature Materials, 2011; DOI: 10.1038/NMAT2998