Kitchen Gadget Inspires Scientist to Make More Effective Plastic Electronics

Fabricating single crystal organic field-effect transistors using ultra-thin polymer membrane for a gate insulator. In the upper row, the membrane is stretched over the transistor before vacuum is applied. In the lower row, the vacuum has been applied and the membrant is adhering to the organic crystal. Photos on the right are close-up views of the transistor, with the organic semiconductor crystal in red. (Credit: Credit: H. T. Yi, et. al.)

One day in 2010, Rutgers physicist Vitaly Podzorov watched a store employee showcase a kitchen gadget that vacuum-seals food in plastic. The demo stuck with him. The simple concept -- an airtight seal around pieces of food -- just might apply to his research: developing flexible electronics using lightweight organic semiconductors for products such as video displays or solar cells.

"Organic transistors, which switch or amplify electronic signals, hold promise for making video displays that bend like book pages or roll and unroll like posters," said Podzorov. But traditional methods of fabricating a part of the transistor known as the gate insulator often end up damaging the transistor's delicate semiconductor crystals.

Drawing inspiration from the food-storage gadget, Podzorov and his colleagues tried an experiment. They suspended a thin polymer membrane above the organic crystal and created a vacuum underneath, causing the membrane to collapse gently and evenly onto the crystal's surface. The result: a smooth, defect-free interface between the organic semiconductor and the gate insulator.

The researchers reported their success in the journal Advanced Materials. In the article,Podzorov and three colleagues describe how a single-crystal organic field effect transistor (OFET) made with this thin polymer gate insulator boosted electrical performance. The researchers further reported that they could remove and reapply membranes to the same crystal several times without degrading its surface.

Organic transistors electrically resemble silicon transistors in computer chips, but they are made of flexible carbon-based molecules that can be printed on sheets of plastic. Silicon transistors are made in rigid, brittle wafers of silicon.

The methods that scientists previously applied to organic transistor fabrication were based on silicon semiconductor processing, explained Podzorov, assistant professor in the Department of Physics and Astronomy, School of Arts and Sciences. These involved high temperatures, high-energy plasmas or chemical reactions, all of which could damage the delicate organic crystal surface and hinder the transistor's performance.

"People have tendencies to go with something they've known for a long time," he said. "In this case, it doesn't work right."

Podzorov's innovation builds upon a decade of Rutgers research in this field, including his invention of the first single crystal organic transistor in 2003. While his latest innovation is still a ways from commercial reality, he sees an immediate application in the classroom.

"Our technique takes 10 minutes," he said. "It should be exciting for students to actually build these devices and immediately see them work, all within one lab session."

Podzorov was actually trying to solve another problem when he first recalled the food packaging demo. He was thinking about how to protect organic crystals from airborne impurities when his lab shipped samples to collaborating scientists in California and overseas.

"We could place our samples between plastic sheets and pull a vacuum," he said. "Then I thought, 'why don't we try doing this for our gate insulator?'"

Funding for the research was provided by the U. S. Department of Energy and the Rutgers Institute for Advanced Materials and Devices for Nanotechnology. Collaborators in Podzorov's lab were postdoctoral researchers Hee Taek Yi and Yuanzhen Chen, and undergraduate student Krzysztof Czelen. The department's machine shop made a custom-designed vacuum chamber for the project

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Journal Reference:

1. H. T. Yi, Y. Chen, K. Czelen, V. Podzorov. Vacuum Lamination Approach to Fabrication of High-Performance Single-Crystal Organic Field-Effect Transistors. Advanced Materials, 2011; 23 (48): 5807 DOI:10.1002/adma.201103305

Scorpions Inspire Scientists in Making Tougher Surfaces for Machinery

Yellow fattail scorpion (Androctonus australis). 
(Credit: © Fyle / Fotolia)

Taking inspiration from the yellow fattail scorpion, which uses a bionic shield to protect itself against scratches from desert sandstorms, scientists have developed a new way to protect the moving parts of machinery from wear and tear.

A report on the research appears in ACS' journal Langmuir.

Zhiwu Han, Junqiu Zhang, Wen Li and colleagues explain that "solid particle erosion" is one of the important reasons for material damage or equipment failure. It causes millions of dollars of damage each year to helicopter rotors, rocket motor nozzles, turbine blades, pipes and other mechanical parts. The damage occurs when particles of dirt, grit and other hard material in the air, water or other fluids strike the surfaces of those parts. Filters can help remove the particles but must be replaced or cleaned, while harder, erosion-resistant materials cost more to develop and make. In an effort to develop better erosion-resistant surfaces, Han and Li's group sought the secrets of the yellow fattail scorpion for the first time. The scorpion evolved to survive the abrasive power of harsh sandstorms.

They studied the bumps and grooves on the scorpions' backs, scanning the creatures with a 3-D laser device and developing a computer program that modeled the flow of sand-laden air over the scorpions. The team used the model in computer simulations to develop actual patterned surfaces to test which patterns perform best. At the same time, the erosion tests were conducted in the simple erosion wind tunnel for groove surface bionic samples at various impact conditions. Their results showed that a series of small grooves at a 30-degree angle to the flowing gas or liquid give steel surfaces the best protection from erosion.

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Journal Reference:

1. Han Zhiwu, Zhang Junqiu, Ge Chao, Wen Li, Luquan Ren.Erosion Resistance of Bionic Functional Surfaces Inspired from Desert Scorpions. Langmuir, 2012; 120120101148000 DOI: 10.1021/la203942r

World's Most Powerful X-Ray Laser Creates 2-Million-Degree Matter

This photograph shows the interior of a Linac Coherent Light Source SXR experimental chamber, set up for an investigation to create and measure a form of extreme, 2-million-degree matter known as “hot, dense matter.” The central part of the frame contains the holder for the material that will be converted by the powerful LCLS laser into hot, dense matter. To the left is an XUV spectrometer and to the right is a small red laser set up for alignment and positioning. (Credit: Photo courtesy of University of Oxford/Sam Vinko)

Researchers working at the U.S. Department of Energy's (DOE) SLAC National Accelerator Laboratory have used the world's most powerful X-ray laser to create and probe a 2-million-degree piece of matter in a controlled way for the first time. This feat, reported inNature, takes scientists a significant step forward in understanding the most extreme matter found in the hearts of stars and giant planets, and could help experiments aimed at recreating the nuclear fusion process that powers the sun.

The experiments were carried out at SLAC's Linac Coherent Light Source (LCLS), whose rapid-fire laser pulses are a billion times brighter than those of any X-ray source before it. Scientists used those pulses to flash-heat a tiny piece of aluminum foil, creating what is known as "hot dense matter," and took the temperature of this solid plasma -- about 2 million degrees Celsius. The whole process took less than a trillionth of a second.

"The LCLS X-ray laser is a truly remarkable machine," said Sam Vinko, a postdoctoral researcher at Oxford University and the paper's lead author. "Making extremely hot, dense matter is important scientifically if we are ultimately to understand the conditions that exist inside stars and at the center of giant planets within our own solar system and beyond."

Scientists have long been able to create plasma from gases and study it with conventional lasers, said co-author Bob Nagler of SLAC, an LCLS instrument scientist. But no tools were available for doing the same at solid densities that cannot be penetrated by conventional laser beams.

"The LCLS, with its ultra-short wavelengths of X-ray laser light, is the first that can penetrate a dense solid and create a uniform patch of plasma -- in this case a cube one-thousandth of a centimeter on a side -- and probe it at the same time," Nagler said.

The resulting measurements, he said, will feed back into theories and computer simulations of how hot, dense matter behaves. This could help scientists analyze and recreate the nuclear fusion process that powers the sun.

"Those 60 hours when we first aimed the LCLS at a solid were the most exciting 60 hours of my entire scientific career," said Justin Wark, leader of the Oxford group. "LCLS is really going to revolutionize the field, in my view."

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Journal Reference:

1. S. M. Vinko, O. Ciricosta, B. I. Cho, K. Engelhorn, H.-K. Chung, C. R. D. Brown, T. Burian, J. Chalupský, R. W. Falcone, C. Graves, V. Hájková, A. Higginbotham, L. Juha, J. Krzywinski, H. J. Lee, M. Messerschmidt, C. D. Murphy, Y. Ping, A. Scherz, W. Schlotter, S. Toleikis, J. J. Turner, L. Vysin, T. Wang, B. Wu, U. Zastrau, D. Zhu, R. W. Lee, P. A. Heimann, B. Nagler, J. S. Wark. Creation and diagnosis of a solid-density plasma with an X-ray free-electron laser. Nature, 2012; DOI: 10.1038/nature10746

Scientists Create First Free-Standing 3-D Cloak

Researchers in the US have, for the first time, cloaked a three-dimensional object standing in free space, bringing the much-talked-about invisibility cloak one step closer to reality.

Published  in the Institute of Physics and German Physical Society's New Journal of Physics, the researchers used a method known as "plasmonic cloaking" to hide an 18-centimetre cylindrical tube from microwaves.Whilst previous studies have either been theoretical in nature or limited to the cloaking of two-dimensional objects, this study shows how ordinary objects can be cloaked in their natural environment in all directions and from all of an observer's positions.

Some of the most recent breakthroughs in the field of invisibility cloaking have focussed on using transformation-based metamaterials -- inhomogeneous, human-made materials that have the ability to bend light around objects -- however, this new approach uses a different type of artificial material -- plasmonic metamaterials.

When light strikes an object, it rebounds off its surface towards another direction, just like throwing a tennis ball against a wall. The reason we see objects is because light rays bounce off materials towards our eyes and our eyes are able to process the information.

Due to their unique properties, plasmonic metamaterials have the opposite scattering effect to everyday materials.

"When the scattered fields from the cloak and the object interfere, they cancel each other out and the overall effect is transparency and invisibility at all angles of observation.

"One of the advantages of the plasmonic cloaking technique is its robustness and moderately broad bandwidth of operation, superior to conventional cloaks based on transformation metamaterials. This made our experiment more robust to possible imperfections, which is particularly important when cloaking a 3D object in free-space," said study co-author Professor Andrea Alu.

In this instance, the cylindrical tube was cloaked with a shell of plasmonic metamaterial to make it appear invisible. The system was tested by directing microwaves towards the cloaked cylinder and mapping the resulting scattering both around the object and in the far-field. The cloak showed optimal functionality when the microwaves were at a frequency of 3.1 gigahertz and over a moderately broad bandwidth.

The researchers, from the University of Texas at Austin, have shown in previous studies that the shape of the object is irrelevant; oddly shaped and asymmetric objects can both be cloaked using this technique.

Moving forward, one of the key challenges for the researchers will be to demonstrate the cloaking of a 3D object using visible light.

"In principle, this technique could be used to cloak light; in fact, some plasmonic materials are naturally available at optical frequencies. However, the size of the objects that can be efficiently cloaked with this method scales with the wavelength of operation, so when applied to optical frequencies we may be able to efficiently stop the scattering of micrometre-sized objects.

"Still, cloaking small objects may be exciting for a variety of applications. For instance, we are currently investigating the application of these concepts to cloak a microscope tip at optical frequencies. This may greatly benefit biomedical and optical near-field measurements," continued Professor Alu.

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Journal Reference:

1. D Rainwater, A Kerkhoff, K Melin, J C Soric, G Moreno, A Al. Experimental verification of three-dimensional plasmonic cloaking in free-space. New Journal of Physics, 2012; 14 (1): 013054 DOI: 10.1088/1367-2630/14/1/013054

Graphene 'Invisible' to Water: How the Extreme Thinness of Graphene Enables Near-Perfect Wetting Transparency

Graphene is the thinnest material known to science. The nanomaterial is so thin, in fact, water often doesn’t even know it’s there. A new study from Rensselaer Polytechnic Institute shows how the extreme thinness of graphene enables near-perfect wetting transparency. The findings could help inform a new generation of graphene-based flexible electronic devices. Additionally, the research suggests a new type of heat pipe that uses graphene-coated copper to cool computer chips. (Credit: Rensselaer/Koratkar)

ScienceDaily (Jan. 23, 2012) — Graphene is the thinnest material known to science. The nanomaterial is so thin, in fact, water often doesn't even know it's there.

Results of the study were published in the journal Nature Materials. The findings could help inform a new generation of graphene-based flexible electronic devices. Additionally, the research suggests a new type of heat pipe that uses graphene-coated copper to cool computer chips.Engineering researchers at Rensselaer Polytechnic Institute and Rice University coated pieces of gold, copper, and silicon with a single layer of graphene, and then placed a drop of water on the coated surfaces. Surprisingly, the layer of graphene proved to have virtually no impact on the manner in which water spreads on the surfaces.

The discovery stemmed from a cross-university collaboration led by Rensselaer Professor Nikhil Koratkar and Rice Professor Pulickel Ajayan.

"We coated several different surfaces with graphene, and then put a drop of water on them to see what would happen. What we saw was a big surprise -- nothing changed. The graphene was completely transparent to the water," said Koratkar, a faculty member in the Department of Mechanical, Aerospace, and Nuclear Engineering and the Department of Materials Science and Engineering at Rensselaer. "The single layer of graphene was so thin that it did not significantly disrupt the non-bonding van der Waals forces that control the interaction of water with the solid surface. It's an exciting discovery, and is another example of the unique and extraordinary characteristics of graphene."

Results of the study are detailed in the Nature Materials paper "Wetting transparency of graphene."

Essentially an isolated layer of the graphite found commonly in our pencils or the charcoal we burn on our barbeques, graphene is single layer of carbon atoms arranged like a nanoscale chicken-wire fence. Graphene is known to have excellent mechanical properties. The material is strong and tough and because of its flexibility can evenly coat nearly any surface. Many researchers and technology leaders see graphene as an enabling material that could greatly advance the advent of flexible, paper-thin devices and displays. Used as a coating for such devices, the graphene would certainly come into contact with moisture. Understanding how graphene interacts with moisture was the impetus behind this new study.

The spreading of water on a solid surface is called wetting. Calculating wettability involves placing a drop of water on a surface, and then measuring the angle at which the droplet meets the surface. The droplet will ball up and have a high contact angle on a hydrophobic surface. Inversely, the droplet will spread out and have a low contact angle on a hydrophilic surface.

The contact angle of gold is about 77 degrees. Koratkar and Ajayan found that after coating a gold surface with a single layer of graphene, the contact angle became about 78 degrees. Similarly, the contact angle of silicon rose from roughly 32 degrees to roughly 33 degrees, and copper increased from around 85 degrees to around 86 degrees, after adding a layer of graphene.

These results surprised the researchers. Graphene is impermeable, as the tiny spaces between its linked carbon atoms are too small for water, or a single proton, or anything else to fit through. Because of this, one would expect that water would not act as if it were on gold, silicon, or copper, since the graphene coating prevents the water from directly contacting these surfaces. But the research findings clearly show how the water is able to sense the presence of the underlying surface, and spreads on those surfaces as if the graphene were not present at all.

As the researchers increased the number of layers of graphene, however, it became less transparent to the water and the contact angles jumped significantly. After adding six layers of graphene, the water no longer saw the gold, copper, or silicon and instead behaved as if it was sitting on graphite.

The reason for this perplexing behavior is subtle. Water forms chemical or hydrogen bonds with certain surfaces, while the attraction of water to other surfaces is dictated by non-bonding interactions called van der Waals forces. These non-bonding forces are not unlike a nanoscale version of gravity, Koratkar said. Similar to how gravity dictates the interaction between Earth and the sun, van der Waals forces dictate the interaction between atoms and molecules.

In the case of gold, copper, silicon, and other materials, the van der Waals forces between the surface and water droplet determine the attraction of water to the surface and dictate how water spreads on the solid surface. In general, these forces have a range of at least several nanometers. Because of the long range, these forces are not disrupted by the presence of a single-atom-thick layer of graphene between the surface and the water. In other words, the van der Waals forces are able to "look through" ultra-thin graphene coatings, Koratkar said.

If you continue to add additional layers of graphene, however, the van der Waals forces increasingly "see" the carbon coating on top of the material instead of the underlying surface material. After stacking six layers of graphene, the separation between the graphene and the surface is sufficiently large to ensure that the van der Waals forces can now no longer sense the presence of the underlying surface and instead only see the graphene coating. On surfaces where water forms hydrogen bonds with the surface, the wetting transparency effect described above does not hold because such chemical bonds cannot form through the graphene layer.

Along with conducting physical experiments, the researchers verified their findings with molecular dynamics modeling as well as classical theoretical modeling.

"We found that van der Waals forces are not disrupted by graphene. This effect is an artifact of the extreme thinness of graphene -- which is only about 0.3 nanometers thick," Koratkar said. "Nothing can rival the thinness of graphene. Because of this, graphene is the ideal material for wetting angle transparency."

"Moreover, graphene is strong and flexible, and it does not easily crack or break apart," he said. "Additionally, it is easy to coat a surface with graphene using chemical vapor deposition, and it is relatively uncomplicated to deposit uniform and homogeneous graphene coatings over large areas. Finally, graphene is chemically inert, which means a graphene coating will not oxidize away. No single material system can provide all of the above attributes that graphene is able to offer."

A practical application of this new discovery is to coat copper surfaces used in dehumidifiers. Because of its exposure to water, copper in dehumidifier systems oxidizes, which in turn decreases its ability to transfer heat and makes the entire device less efficient. Coating the copper with graphene prevents oxidation, the researchers said, and the operation of the device is unaffected because graphene does not change the way water interacts with copper. This same concept may be applied to improve the ability of heat pipes to dissipate heat from computer chips, Koratkar said.

"It's an interesting idea. The graphene doesn't cause any significant change to the wettability of copper, and at the same time it passivates the copper surface and prevents it from oxidizing," he said.

Along with Koratkar and Ajayan, co-authors of the paper are Yunfeng Shi, assistant professor in the Department of Materials Science and Engineering at Rensselaer; Rensselaer mechanical engineering graduate students Javad Rafiee, Abhay Thomas, and Fazel Yavari; Rensselaer physics graduate student Xi Mi; and Rice mechanical and materials engineering graduate student Hemtej Gullapalli.

This research was supported in part by the Advanced Energy Consortium (AEC); the National Science Foundation (NSF); and the Office of Naval Research (ONR) graphene Multidisciplinary University Research Initiative (MURI).

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Journal Reference:

1. Javad Rafiee, Xi Mi, Hemtej Gullapalli, Abhay V. Thomas, Fazel Yavari, Yunfeng Shi, Pulickel M. Ajayan, Nikhil A. Koratkar. Wetting transparency of graphene. Nature Materials, 2012; DOI: 10.1038/NMAT3228

Ultrafast Magnetic Processes Observed 'Live' Using an X-Ray Laser

Detail of the structure of cupric oxide (CuO). The copper atoms (green) carry a magnetic moment, behaving like small compass needles. The direction of the magnetic moment is illustrated by a red arrow. A point means that the arrow is pointing out of the surface (we are looking at its sharp end), a cross shows that the arrow is pointing into the surface (we are looking at its tail end). The magnetic structure changes significantly as the temperature increases above 213 Kelvin (around -60°C). One aspect of this change is a difference in the period of the magnetic order. Unlike the ordering at low temperatures, the magnetic structure in the temperature range 213 K to 230 K is incommensurate: its period does not ‘fit’ with the period of the crystal structure of copper and oxygen atoms. To be precise, a full rotation of the direction of the magnetic moment does not require exactly four atomic separations, but a little more or a little less, depending on the direction. (Credit: Image courtesy of Paul Scherrer Institut (PSI))

ScienceDaily (Jan. 23, 2012) — In first-of-their-kind experiments performed at the American X-ray laser LCLS, a collaboration led by researchers from the Paul Scherrer Institute has been able to precisely follow how the magnetic structure of a material changes.

This is another milestone, because such investigations will also be a major focus of research at the planned Swiss X-ray Laser, Swiss FEL, at PSI. The results could contribute to the development of new technologies for magnetic storage media for the future.The study was carried out on cupric oxide (CuO). The change of structure was initiated by a laser pulse, and then, with the help of short X-ray pulses, near-instantaneous images were obtained at different points in time for individual intermediate steps during the process. It appears as if the structure begins to change 400 femtoseconds after the laser pulse strikes (1 femtosecond = 0.000 000 000 000 001 seconds). Apparently, the fundamental magnets within the material need that much time to communicate with each other and then react. In addition to this scientific result, the work proves that it is actually possible with X-ray lasers to follow certain types of extremely rapid magnetic processes.

The researchers have reported on their work in the latest edition of the technical journal Physical Review Letters (PRL).

Materials with particular magnetic properties are the basis of many current technologies, in particular, data storage on hard discs and in other media. For this, the magnetic orientation in the material is most often used: the atoms in the material behave to some extent like tiny rod magnets ("spins"). These mini-magnets can be oriented in different ways and information can be stored through their orientation. For efficient data storage, it is crucial that old data can be rapidly overwritten. This is possible if the magnetic orientation in a material can be altered in a very short time. To develop innovative materials which can store data quickly, it is therefore important to understand exactly how this change occurs as a function of time.

Magnetic orientation in motion

In experiments performed at the X-ray laser LCLS at Stanford, California, a collaboration led by researchers from the Paul Scherrer Institute have been able to study the magnetic orientation in cupric oxide, CuO. This material demonstrates completely different magnetic orientations depending on temperature: Below -60°C, the spins, which function in the copper atoms (Cu) like magnets, point periodically in one direction and then the opposite; between -60°C and -43°C, they are arranged helically, as if they were forming a spiral staircase. Although the spin orientations for the two arrangements have been known for some time, the time required to move from one arrangement to the other has only now been shown by the experiment.

"In our investigation, we began with a 'cold' sample and then heated it with an intense flash of light from an optical laser," explains Steven Johnson, spokesman for the PSI experiment. "Shortly after this, we determined the structure of the sample by illuminating it with an extremely short pulse from an X-ray laser. When we repeated this at different time intervals between the flash of light and the X-ray pulse, we were able to reconstruct the course of the change in the magnetic structure."

Mini-magnets need 400 femtoseconds to agree amongst themselves.

The results show that it takes about 400 femtoseconds before the magnetic structure begins to alter visibly. Then the structure gradually reaches its final state. The more intense the initiating flash of light, the faster the change of state. "The spins of all copper atoms are involved in the magnetic structure. Thus the atoms at opposite ends of the material must be coordinated before the structure can change. This takes 400 femtoseconds," explains Urs Staub, one of the PSI researchers responsible. "For cupric oxide, that is the fundamental limit; it simply cannot happen faster than that. This depends upon how strongly the spins are coupled between neighbouring atoms."

There is a good reason why the researchers were particularly interested in cupric oxide. Along with the screw-like magnetic orientation that occurs between -60°C and -43°C, the material is also 'multiferroic', a material where electrical and magnetic processes mutually influence one another. These materials have many different potential areas of application where magnetism and electronics interact.

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Journal Reference:

1. S. Johnson, R. de Souza, U. Staub, P. Beaud, E. Möhr-Vorobeva, G. Ingold, A. Caviezel, V. Scagnoli, W. Schlotter, J. Turner, O. Krupin, W.-S. Lee, Y.-D. Chuang, L. Patthey, R. Moore, D. Lu, M. Yi, P. Kirchmann, M. Trigo, P. Denes, D. Doering, Z. Hussain, Z.-X. Shen, D. Prabhakaran, A. Boothroyd. Femtosecond Dynamics of the Collinear-to-Spiral Antiferromagnetic Phase Transition in CuO.Physical Review Letters, 2012; 108 (3) DOI:10.1103/PhysRevLett.108.037203

Computer scientist cracks mysterious 'Copiale Cipher'

ScienceDaily (Oct. 25, 2011) — The manuscript seems straight out of fiction: a strange, handwritten message in abstract symbols and Roman letters meticulously covering 105 yellowing pages hidden in the depths of an academic archive.

Now, more than three centuries after it was devised, the 75,000-character Copiale Cipher finally has been broken.

The mysterious cryptogram, bound in gold and green brocade paper, reveals the rituals and political leanings of an 18th-century secret society in Germany. The rituals detailed in the document indicate the society had a fascination with eye surgery and ophthalmology, though it seems members of the society were not eye doctors.

"This opens up a window for people who study the history of ideas and the history of secret societies," said computer scientist Kevin Knight of the USC Viterbi School of Engineering, part of the international team that finally cracked the cipher. "Historians believe that secret societies have had a role in revolutions, but all that is yet to be worked out, and a big part of the reason is because so many documents are enciphered."

To break the cipher, Knight and colleagues Beáta Megyesi and Christiane Schaefer of Uppsala University in Sweden tracked down the original manuscript, which was found in the East Berlin Academy after the Cold War and now is in a private collection. They transcribed a machine-readable version of the text, using a computer program created by Knight to help quantify the co-occurrences of certain symbols and other patterns.

"When you get a new code and look at it, the possibilities are nearly infinite," Knight said. "Once you come up with a hypothesis based on your intuition as a human, you can turn over a lot of grunt work to the computer."

With the cipher, the codebreaking team began not even knowing the language of the encrypted document. But because they had a hunch about the Roman and Greek characters distributed throughout the manuscript, they isolated these from the abstract symbols and attacked it as the true code.

"It took quite a long time and resulted in complete failure," Knight said.

After trying 80 languages, the cryptography team realized the Roman characters were "nulls" intended to mislead the reader. It was the abstract symbols that held the message.

The team later tested the hypothesis that abstract symbols with similar shapes represented the same letter or groups of letters. Eventually, the first meaningful words of German emerged: "Ceremonies of Initiation," followed by "Secret Section."

For more information about the method of decipherment, visit http://stp.lingfil.uu.se/%7Ebea/copiale/

Knight now is targeting other coded messages, including ciphers sent by the Zodiac Killer, a serial murderer who sent taunting messages to the press and has never been caught. Knight also is applying his computer-assisted codebreaking software to other famous unsolved codes such as the last section of "Kryptos," an encrypted message carved into a granite sculpture on the grounds of CIA headquarters, and the Voynich Manuscript, a medieval document that has baffled professional cryptographers for decades.

But for Knight, the trickiest language puzzle of all is still everyday speech. A senior research scientist in the Intelligent Systems Division of the USC Information Sciences Institute, Knight is one of the world's leading experts on machine translation -- teaching computers to turn Chinese into English or Arabic into Korean.

"Translation remains a tough challenge for artificial intelligence," said Knight, whose translation software has been adopted by Apple and Intel, among other companies.

With researcher Sujith Ravi, who received a Ph.D. in computer science from USC in 2011, Knight has been approaching translation as a cryptographic problem, which could not only improve human language translation but also could be useful in translating languages that are not currently spoken by humans, including ancient languages and animal communication.

The National Science Foundation funded Knight's cryptography and translation research. The Copiale Cipher work was presented as part of an invited presentation at this year's meeting of The Association for Computational Linguistics.

For a video on Kevin Knight and the Copiale Cipher, visit http://www.youtube.com/watch?v=Eam0Tk-1FyI

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