Thursday, April 7, 2011

Search for advanced materials aided by discovery of hidden symmetries in nature

 A new way of understanding the structure of proteins, polymers, minerals, and engineered materials will be published in the May 2011 issue of the journal Nature Materials. The discovery by two Penn State University researchers is a new type of symmetry in the structure of materials, which the researchers say greatly expands the possibilities for discovering or designing materials with desired properties.

The research is expected to have broad relevance in many development efforts involving physical, chemical, biological, or engineering disciplines including, for example, the search for advanced ferroelectric ferromagnet materials for next-generation ultrasound devices and computers. The paper describing the research will be posted early online by the journal on 3 April 2011, prior to its publication in the journal's May 2011 print edition.

Before the publication of this paper, scientists and engineers had five different types of symmetries to use as tools for understanding the structures of materials whose building blocks are arranged in fairly regular patterns. Four types of symmetries had been known for thousands of years -- called rotation, inversion, rotation inversion, and translation -- and a fifth type -- called time reversal -- had been discovered about 60 years ago. Now, Gopalan and Litvin have added a new, sixth, type, called rotation reversal. As a result, the number of known ways in which the components of such crystalline materials can be combined in symmetrical ways has multiplied from no more than 1,651 before to more than 17,800 now. "We mathematically combined the new rotation-reversal symmetry with the previous five symmetries and now we know that symmetrical groups can form in crystalline materials in a much larger number of ways," said Daniel B. Litvin, distinguished professor of physics, who coauthored the study with Venkatraman Gopalan, professor of materials science and engineering.

The new rotation-reversal symmetry enriches the mathematical language that researchers use to describe a crystalline material's structure and to predict its properties. "Rotation reversal is an absolutely new approach that is different in that it acts on a static component of the material's structure, not on the whole structure all at once," Litvin said. "It is important to look at symmetries in materials because symmetry dictates all natural laws in our physical universe."

The most simple type of symmetry -- rotation symmetry -- is obvious, for example, when a square shape is rotated around its center point: the square shows its symmetrical character by looking exactly the same at four points during the rotation: at 90 degrees, 180 degrees, 270 degrees, and 360 degrees. Gopalan and Litvin say their new rotation-reversal symmetry is obvious, as well, if you know where to look.

The "eureka moment" of the discovery occurred when Gopalan recognized that the simple concept of reversing the direction of a spiral-shaped structure from clockwise to counterclockwise opens the door to a distinctly new type of symmetry. Just as a square shape has the quality of rotation symmetry even when it is not being rotated, Gopalan realized that a spiral shape has the quality of rotation-reversal symmetry even when it is not being physically forced to rotate in the reverse direction. Their further work with this rotation-reversal concept revealed many more structural symmetries than previously had been recognized in materials containing various types of directionally oriented structures. Many important biological molecules, for example, are said to be either "right handed" or "left handed," including DNA, sugars, and proteins.

"We found that rotation-reversal symmetry also exists in paired structures where the partner components lean toward each other, then away from each other in paired patterns symmetrically throughout a material," Gopalan said. These "tilting octahedral" structures are common in a wide variety of crystalline materials, where all the component structures are tightly interconnected by networks of shared atoms. The researchers say it is possible that components of materials with rotation-reversal symmetry could be engineered to function as on/off switches for a variety of novel applications.

The now-much-larger number of possible symmetry groups also is expected to be useful in identifying materials with unusual combinations of properties. "For example, the goal in developing a ferroelectric ferromagnet is to have a material in which the electrical dipoles and the magnetic moments coexist and are coupled in the same material -- that is, a material that allows electrical control of magnetism -- which would be very useful to have in computers," Gopalan said. The addition of rotation-reversal symmetry to the materials-science toolbox may help researchers to identify and search for structures in materials that could have strong ferroelectric and ferromagnetic properties.

Gopalan and Litvin said a goal of their continuing research is to describe each of the more than 17,800 different combinations of the six symmetry types to give materials scientists a practical new tool for significantly increasing the efficiency and effectiveness in finding novel materials. The team also plans to conduct laboratory experiments that make use of their theoretical work on rotation-reversal symmetry. "We have done some predictions, we will test those predictions experimentally," Litvin said. "We are in the very early stages of implementing the results we have described in our new theory paper." Gopalan said, for example, that he has predicted new forms for optical properties in the commonplace quartz crystals that are used widely in watches and electronic equipment, and that his group now is testing these predictions experimentally.

The National Science Foundation provided financial support for this research through its Materials Research Science and Engineering Centers program.

Story Source:

The above story is reprinted  from materials provided by Penn State, via EurekAlert!, a service of AAAS.

Journal Reference:

Venkatraman Gopalan, Daniel B. Litvin. Rotation-reversal symmetries in crystals and handed structures. Nature Materials, 2011; DOI: 10.1038/nmat2987

Berkshire Exec Resigns (Apparently) Over Lubrizol Bid

Some of you may have heard the news that Berkshire Hathaway executive David L. Sokol has resigned. Sokol bought 100,000 shares of Lubrizol and suggested to Buffett that Berkshire buy the whole company. Here’s the Lubrizol-related excerpt from Buffett’s statement about the resignation:

Finally, Dave brought the idea for purchasing Lubrizol to me on either January 14 or 15. Initially, I was unimpressed, but after his report of a January 25 talk with its CEO, James Hambrick, I quickly warmed to the idea. Though the offer to purchase was entirely my decision, supported by Berkshire’s Board on March 13, it would not have occurred without Dave’s early efforts.

That brings us to our second set of facts. In our first talk about Lubrizol, Dave mentioned that he owned stock in the company. It was a passing remark and I did not ask him about the date of his purchase or the extent of his holdings.

Shortly before I left for Asia on March 19, I learned that Dave first purchased 2,300 shares of Lubrizol on December 14, which he then sold on December 21. Subsequently, on January 5, 6 and 7, he bought 96,060 shares pursuant to a 100,000-share order he had placed with a $104 per share limit price.

Dave’s purchases were made before he had discussed Lubrizol with me and with no knowledge of how I might react to his idea. In addition, of course, he did not know what Lubrizol’s reaction would be if I developed an interest. Furthermore, he knew he would have no voice in Berkshire’s decision once he suggested the idea; it would be up to me and Charlie Munger, subject to ratification by the Berkshire Board of which Dave is not a member.

As late as January 24, I sent Dave a short note indicating my skepticism about making an offer for Lubrizol and my preference for another substantial acquisition for which MidAmerican had made a bid. Only after Dave reported on the January 25 dinner conversation with James Hambrick did I get interested in the acquisition of Lubrizol.

Neither Dave nor I feel his Lubrizol purchases were in any way unlawful. He has told me that they were not a factor in his decision to resign.

Dave’s letter was a total surprise to me, despite the two earlier resignation talks. I had spoken with him the previous day about various operating matters and received no hint of his intention to resign. This time, however, I did not attempt to talk him out of his decision and accepted his resignation.

This seems to me a case of an appearance of conflict of interest rather than a real conflict of interest. Sokol thought Lubrizol was a good investment. He suggested that it would be a good investment for his company, too. Engineering an entire deal to make a tidy—albeit $3 million—profit would be the tail wagging the dog.


Profile: Alfredo M. Ayala Jr., Disney Imagineer

Alfredo M. Ayala Jr. majored in chemistry in college, but these days he dabbles in a very special kind of alchemy. He’s been with Walt Disney Imagineering Research and Development for over 15 years, where his job is to create new illusions and experiences for Disney park guests. And as he explained Sunday at the ACS national meeting in Anaheim, it was organic chemistry that got his foot in the door.

Ayala said he fell in love with science as a boy when he saw “Antimatter”, an animated look at the atomic world by Carlos Gutierrez, a UCLA film major turned chemistry major and organic chemistry professor. As it so happened, Gutierrez became Ayala’s mentor when the young Ayala came to Cal State L.A., through Gutierrez’s program for engaging junior high and high school students interested in biomedical sciences. At Cal State L.A., Ayala followed his interests in chemistry and in computers, taking engineering coursework in addition to chemistry. He was an undergraduate researcher in Gutierrez’s organic chemistry lab when he applied for an internship with the Disney company.

Disney asked its prospective interns to write a paragraph about why they wanted the gig. But instead of just gushing about how cool it would be to work with the company, Ayala took a different tack. He knew Imagineers were looking to reformulate the skin material for the Pirates of the Caribbean attraction, which at the time contained chromium, a non-chlorine scavenger, as a heat stabilizer. By not having a chlorine scavenger, hydrochloric acid was being produced in reactions with water, which in turn corroded parts that would need to be replaced periodically.

Ayala sent Disney three proposals for alternative skin formulas, based on some chemistry he had done forming precursors to analogs of 18-crown-6 ethers in the Gutierrez group. In this 1995 Tet. Lett. paper the group begins with some tin-containing acetals and forms two different crown ether precursors depending on whether they add 1,2-dibromoethane or 2-chloroethanol. “Note we were scavenging chlorine and bromine- this is how I got the idea,” Ayala says.

His ingenuity on the application paid off in the form of an interview. “That was what got me in,” he says. He’s been with Disney ever since.

“You’d be surprised how much chemistry goes on at Disney,” Ayala says. Building one Disney attraction takes experts in 140 disciplines, from mechanical engineering to art. And chemistry challenges are everywhere at the parks, Ayala says. Research in materials science for skin and other applications is an active area. “The skin formulation I worked on as an intern is obsolete,” he says. An entire department is dedicated to making eco-friendlier and more durable paints and coatings. But perhaps the biggest chemistry challenge in the parks is water- from transportation to treatment to recycling, he says. Disney has an environmental group with labs in Zurich and collaborations with UCLA and Carnegie Mellon Universities to find those kinds of solutions.

Although chemistry got him his start at the company, “I don’t do chemistry right now,” Ayala says. One of the best things about working for Disney is the opportunity to explore other interests and evolve your job to pursue them. An interest in optics led to his becoming the lead optics designer for the “Mission: Space” attraction. An interest in special effects, UV paints, and lasers led to his becoming the special effects lead for the “Kim Possible World Showcase Adventure” at Epcot at Walt Disney World, , and the principal developer of the technology behind the “Finding Nemo Submarine Voyage“. His current project is introducing a new robotic animation system for the parks, which will make robots reactive and responsive to park guests. With chemistry training “what you have is a base,” Ayala says. “You can build on it.”

“For me, going to work is going to play,” Ayala says. “I play every day.”

Interested in becoming an Imagineer? There are a few avenues for getting started. One is the worldwide ImagiNations Design Competition, held annually. Here is an example of a project for the competition. Disney also offers chemistry internships in Florida, says Angela Winstead of Morgan State University in Baltimore, who coordinated the Society Committee on Education career panel where Ayala spoke in Anaheim.


Small scale chemistry could lead to big improvements for biodegradable polymers

Using a small block of aluminum with a tiny groove carved in it, a team of researchers from the National Institute of Standards and Technology and the Polytechnic Institute of New York University is developing an improved “green chemistry” method for making biodegradable polymers. Their recently published work is a prime example of the value of microfluidics, a technology more commonly associated with inkjet printers and medical diagnostics, to process modeling and development for industrial chemistry.

“We basically developed a microreactor that lets us monitor continuous polymerization using enzymes,” explains NIST materials scientist Kathryn Beers. “These enzymes are an alternate green technology for making these types of polymers—we looked at a polyester—but the processes aren’t really industrially competitive yet,” she says. Data from the microreactor, a sort of zig-zag channel about a millimeter deep crammed with hundreds of tiny beads, shows how the process could be made much more efficient. The team believes it to be the first example of the observation of polymerization with a solid-supported enzyme in a microreactor.

The group studied the synthesis of PCL (Polycaprolactone), a biodegradable polyester used in applications ranging from medical devices to disposable tableware. PCL, Beers explains, most commonly is synthesized using an organic tin-based catalyst to stitch the base chemical rings together into the long polymer chains. The catalyst is highly toxic, however, and has to be disposed of.

Modern biochemistry has found a more environmentally friendly substitute in an enzyme produced by the yeast strain Candida antartica, Beers says, but standard batch processes—in which the raw material is dumped into a vat, along with tiny beads that carry the enzyme, and stirred—is too inefficient to be commercially competitive. It also has problems with enzyme residue contaminating and degrading the product.

By contrast, Beers explains, the microreactor is a continuous flow process. The feedstock chemical flows through the narrow channel, around the enzyme-coated beads, and, polymerized, out the other end. The arrangement allows precise control of temperature and reaction time, so that detailed data on the chemical kinetics of the process can be recorded to develop an accurate model to scale the process.

“The small-scale flow reactor allows us to monitor polymerization and look at the performance recyclability and recovery of these enzymes,” Beers says. “With this process engineering approach, we’ve shown that continuous flow really benefits these reactors. Not only does it dramatically accelerate the rate of reaction, but it improves your ability to recover the enzyme and reduce contamination of the product.” A forthcoming follow-up paper, she says, will present a full kinetic model of the reaction that could serve as the basis for designing an industrial scale process.

While this study focused on a specific type of enzyme-assisted polymer reactions, the authors observe, “it is evident that similar microreactor-based platforms can readily be extended to other systems; for example, high-throughput screening of new enzymes and to processes where continuous flow mode is preferred.”

More information: S. Kundu, et al. Continuous flow enzyme-catalyzed polymerization in a microreactor. J. Am. Chem. Soc. DOI:10.1021/ja111346c

Provided by National Institute of Standards and Technology (news : web)

From crankcase to gas tank: New microwave method converts used motor oil into fuel

That dirty motor oil that comes out of your car or truck engine during oil changes could end up in your fuel tank, according to a report presented here today at the 241st National Meeting & Exposition of the American Chemical Society (ACS). It described development of a new process for recycling waste crankcase oil into gasoline-like fuel — the first, they said, that uses microwaves and has "excellent potential" for going into commercial use.

"Transforming used motor into gasoline can help solve two problems at once," said study leader Howard Chase, Professor of Biochemical Engineering at the University of Cambridge in the United Kingdom. "It provides a new use for a waste material that's too-often disposed of improperly, with harm to the environment. In addition, it provides a supplemental fuel source for an energy-hungry world."

Estimates suggest that changing the oil in cars and trucks produces about 8 billion gallons of used motor oil each year around the world. In the United States and some other countries, some of that dirty oil is collected and re-refined into new lubricating oil or processed and burned in special furnaces to heat buildings. Chase noted, however, that such uses are far from ideal because of concerns over environmental pollution from re-refining oil and burning waste oil. And in many other countries, used automotive waste oil is discarded or burned in ways that can pollute the environment.

Scientists thus are looking for new uses for that Niagara of waste oil, growing in volume as millions of people in China, India, and other developing countries acquire cars. Among the most promising recycling techniques is pyrolysis, a process that involves heating oil at high temperatures in the absence of oxygen. Pyrolysis breaks down the waste oil into a mix of gases, liquids, and a small amount of solids. The gases and liquids can then be chemically converted into gasoline or diesel fuel. However, the current processes heat the oil unevenly, producing gases and liquids not easily converted into fuel.

Chase and his research team say the new method overcomes this problem and uses their new pyrolysis technology. In lab studies, his doctoral students, Su Shiung Lam and Alan Russell, mixed samples of waste oil with a highly microwave-absorbent material and then heated the mixture with microwaves. The pyrolysis process appears to be highly efficient, converting nearly 90 percent of a waste oil sample into fuel. So far, the scientists have used the process to produce a mixture of conventional gasoline and diesel.

"Our results indicate that a microwave-heated process shows exceptional promise as a means for recycling problematic waste oil for use as ," Chase and Lam said. "The recovery of valuable oils using this process shows advantage over traditional processes for oil recycling and suggests excellent potential for scaling the process to the commercial level."

Provided by American Chemical Society (news : web)

Antibiotics wrapped in nanofibers turn resistant disease-producing bacteria into ghosts

 Encapsulating antibiotics inside nanofibers, like a mummy inside a sarcophagus, gives them the amazing ability to destroy drug-resistant bacteria so completely that scientists described the remains as mere "ghosts," according to a report today at the the 241st National Meeting & Exposition of the American Chemical Society (ACS).

Mohamed H. El-Newehy, Ph.D., leader of the nanofibers research team, said the new technology has potentially important applications in the on-going battle against antibiotic-resistant infections. Estimates suggest that more than 100,000 people in the United States alone develop such infections each year, with nearly 20,000 deaths. Health care costs from those infections may exceed $20 billion annually.

"The rapid emergence of resistant to commonly used antibiotics has become a serious public health problem," said El-Newehy. "There is an urgent need to identify new antibiotics that work in different ways that can overcome resistance. Our approach is not a new antibiotic, but a new way of delivering existing antibiotics."

That approach, El-Newehy explained, could make new treatments available to patients much faster than trying to discover and develop brand-new medicines, a process that typically takes 10-12 years and costs $800 million to almost $2 billion. It could be used against a broad range of bacteria to fight disease, prevent bacterial and fungal contamination in the food industry, inhibit the growth of microorganisms in drinking water and enhance the effects of chemotherapy, he added.

It involves putting common antibiotics inside nanofibers made of polyvinyl alcohol and polyethylene oxide — wisps of plastic-like material so small that peach hair or a strand of spider silk are gigantic by comparison. Nanofibers can't even be seen under a regular microscope, and almost a billion could be lined up side-by-side along the length of a yard stick.

El-Newehy's group knew that nanofibers have special properties due to their high surface area to weight ratio. Those properties have kindled research on multiple biomedical applications nanofibers, including wound dressings, medical textiles, antibacterial materials to control post-operative inflammation, and new ways of delivering drugs. They decided to test the effects of nanofibers with multiple antibiotics encapsulated directly into fiber, using laboratory cultures of various microbes. Antibiotics wrapped inside nanofibers were highly effective in killing a variety of disease causing bacteria and fungi, including Escherichia coli and Pseudomonas aeruginosa, two increasingly drug-resistant microbes.

"When treated with antibiotics wrapped in nanofibers, the microbes were severely damaged and many cells were enlarged, elongated, fragmented, or left as just empty ghosts," El-Newehy said. "The fibers by themselves, without antibiotic did not affect the bacteria. They seem to work by boosting the power of the . By wrapping the anti-microbial agents in the fibers, it makes the drug action more focused and the agents are effective for longer period of time than with conventional delivery techniques."

El-Newehy, with the Petrochemical Research Chair, Department of Chemistry College of Science, King Saud University, Riyadh, Riyadh, Saudi Arabia, said that besides drug delivery, nanofibers are being used for tissue engineering, wound dressing, medical textiles and antimicrobial materials that can be used to control post-operative inflammation, promote wound healing and dressing, especially for diabetic ulcers.

Salem Al-Deyab, Ph.D., the supervisor of Petrochemical Research Chair at King Saud University, said that this study was funded by the Petrochemical Research Chair at King Saud University, Saudi Arabia. In addition, Petrochemical Research Chair has the lead in the possession of the first machine (Nanospider) for producing nanofibers in Saudi Arabia, said Al-Deyab. Officials plan a major effort to develop the Nanofibers Research Center at Petrochemical Research Chair to become a major center for Research for different applications at King Saud University, said Al-Deyab.

Provided by American Chemical Society (news : web)