Caltech-Led Team Creates Damage-Tolerant Metallic Glass

Amorphous palladium-based alloy demonstrates unprecedented level of combined toughness and strength; could be of use in biomedical implants

PASADENA, Calif.—Glass is inherently strong, but when it cracks or otherwise fails, it proves brittle, shattering almost immediately. Steel and other metal alloys tend to be tough—they resist shattering—but are also relatively weak; they permanently deform and fail easily.

The ideal material, says Marios Demetriou, a senior research fellow at the California Institute of Technology (Caltech), has the advantage of being both strong and tough—a combination called damage tolerance, which is more difficult to come by than the layperson might think. "Strength and toughness are actually very different, almost mutually exclusive," he explains. "Generally, materials that are tough are also weak; those that are strong, are brittle."

And yet, Demetriou—along with William Johnson, Caltech's Ruben F. and Donna Mettler Professor of Engineering and Applied Science, and their colleagues—report in a recent issue of the journal Nature Materials that they have developed just such a material. Their new alloy—a combination of the noble metal palladium, a small fraction of silver, and a mixture of other metalloids—has shown itself in tests to have a combination of strength and toughness at a level that has not previously been seen in any other material.

"Our study demonstrates for the first time that this class of materials, the metallic glasses, has the capacity to become the toughest and strongest ever known," Demetriou says. Indeed, the researchers write in their paper, these materials allow for "pushing the envelope of damage tolerance accessible to a structural metal."

What gives metallic glasses their unusual qualities is the fact that they are made of metals—with the inherent toughness that comes with that class of material—but have the internal structure of glass, and thus its strength and hardness. (Despite its name, it is this internal structure that is the only glasslike thing about metallic glass: the material is not transparent, Demetriou notes, and is both optically and electronically like metal.)

The problem with trying to increase strength in ordinary metals is that their atoms are organized in a crystal lattice, Demetriou explains. "And whenever you try to make something as perfect as a crystal, inevitably you will create defects," he says. Those defects, under stress, become mobile, and other atoms move easily around them, producing permanent deformations. While this rearrangement around defects results in an ability to block or cap off an advancing crack, producing toughness, it also limits the strength of the material.

A notched, glassy palladium sample does not shatter after severe bending, despite the generation of multiple cracks.
Credit: LBNL/Maximilien E. Launey

On the other hand, glass has an amorphous structure, its atoms scattered about without a specific discernible pattern. In metallic glasses—also called amorphous metals because of their structure—this results in an absence of the extended defects found in crystalline metals. The actual defects in glasses are generally much smaller in size and only become active when exposed to much higher stresses, resulting in higher strengths. However, this also means that the strategy used in ordinary metals to stop a crack from growing ever longer—the easy and rapid rearrangement of the atoms around defects into a sort of cap at the leading edge of a crack—is not available.

"When defects in the amorphous structure become active under stress, they coalesce into slim bands, called shear bands, that rapidly extend and propagate through the material," says Demetriou. "And when these shear bands evolve into cracks, the material shatters."

It was this tendency to shatter that was thought to be one of the limiting factors of metallic glasses, which were first developed in the 1960s at Caltech. The assumption was that, despite their many benefits, they could never match or exceed the toughness of the toughest steels.

But what the Caltech scientists found, much to their surprise, was that creating more of a problem could actually solve the problem.

In the new palladium alloy, so many shear bands form when the material is put under stress that it "actually leads to higher toughness, because the bands interact and form networks that block crack propagation," Demetriou explains. In other words, the number of shear bands that form, intersect, and multiply at the tip of an evolved crack is so high that the crack is blocked and cannot travel very far. In essence, then, the shear bands act as a shield, preventing shattering. Thus, the palladium glass acts very much like the toughest of steels, using an analogous blocking mechanism of arresting cracks.

"And," Demetriou adds, "this high toughness does not come at the expense of strength. This material has both strength and toughness, which is why it falls so far outside what's previously been possible. That's why this material is so special."

The palladium alloy described in the paper could soon be of use in biomedical implants, says Demetriou. "One example is dental implants," Demetriou says. "Many noble-metal alloys, including palladium, are currently used in dentistry due to their chemical inertness and resistance to oxidation, tarnish, and corrosion. Owing to its superior damage tolerance, the present palladium glass can be thought of as a superior alternative to conventional palladium dental alloys. Plus, the absence of any elements considered toxic or allergenic—nickel, copper, aluminum—from the composition of this alloy will likely promote good biological compatibility."

The class of such tough metallic glasses potentially could be used in other structural applications like automotive and aerospace components, the team says. But this particular alloy is unlikely to be part of any large-scale manufacturing process. "It's prohibitively expensive," says Demetriou. "The cost is much too high for any large-scale, widespread use."

Still, he notes, the fact that it was created at all, with these particular properties, tells scientists that this level of toughness and strength is well within reach. Now it's just a matter of figuring out specifically what gives this alloy its unique damage tolerance, and how that can be replicated with an alloy containing less-expensive, less-precious metals. 

In addition to Demetriou and Johnson, the other authors on the Nature Materials paper, "A Damage-Tolerant Glass," are Caltech graduate student Glenn Garrett, visitor in applied physics and materials science Joseph Schramm, and lecturer in applied physics and materials science Douglas Hofmann; Robert Ritchie from the Lawrence Berkeley National Laboratory (LBNL) and UC Berkeley; and Maximilien Launey, formerly of LBNL and now at the Cordis Corporation. Their work was supported by the National Science Foundation and the U.S. Department of Energy.

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Lori Oliwenstein
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John Dabiri Named to EBONY "Power List"

Congratulations to Caltech's John Dabiri, who has been named to EBONY magazine's annual Power 100 List. Among his companions there: President Barack Obama, Wyclef Jean, Michael Jordan, and Will Smith.

"I'm honored to be included in a list with so many distinguished leaders from all walks of life," Dabiri says. "I hope that my inclusion in the list encourages the next generation of young people that they too can use science and engineering to positively impact their communities. And I especially hope that we will start to see them in greater numbers here at Caltech."

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Kathy Svitil
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Engineering for the Other Half

"Nothing happens in industry from the sole effort of a single mind working in isolation." That, says Visiting Professor of Mechanical Engineering Ken Pickar, is a lesson every young engineer needs to learn. And it's a recurring theme of his course E/ME 105, "Product Design for the Developing World." The course, created with input from the Caltech chapter of Engineers for a Sustainable World (ESW), emphasizes that products don't bring themselves to market unaided—that engineers can be the agents of lasting global change—and that there's more to innovation than just cleverness.

This year's class consisted of sixteen Techers, along with another sixteen attending SaintGITS, a technical university in southwestern India. Their task: define and attempt to solve a number of problems affecting India's poorest residents.

Under the guidance of Professor Jason Issac, the SaintGITS students did much of the initial research, interviewing local business owners, farmers, and professionals. They uncovered several recurring themes, including reduced costs and the empowerment of women, who are largely underrepresented in the workforce. Ultimately, the group proposed seven projects: three involving India's rice and rubber industries, two dealing with health care, and two addressing the insufficiencies of the country's power grid. Teams then began brainstorming via instant messaging and videoconferences (evening in Pasadena corresponds to morning in India), and on December 7 they presented their results.

One proposed device, roughly the size of a deck of cards, is intended to be strapped outside the window of a commuter bus. Over the course of a one-hour ride, its tiny wind-driven turbine would provide enough electricity to charge a cell phone battery. Another project, a personal sleeping fan, proposes to combat India's fierce equatorial heat without air conditioning. It resembles a similar device currently marketed by a UK company, but by lowering the engineering tolerances ("do all the vents need to be exactly the same diameter?"), the team was able to drop costs dramatically.

Given the specific problems being addressed, not every one of the group's projects would likely find a market in the West. However, Pickar encouraged his students to consider the possibility of filing for intellectual property protection where appropriate. For instance, one concept, arising from discussions with medical professionals, was a device to simplify the process of transferring hospital patients between bed and wheelchair. Its design elegantly integrates quick-release hinges and rollers into a large collapsible board. Another was a set of crutches adaptable for use on staircases. By providing extra contact surfaces, they would replace the traditional plant-swing-and-hop procedure with a much gentler lift-and-lower motion, reducing the likelihood of tumbles. In fact, the team's first two prototypes (fashioned from PVC pipe and metal tubing) proved so stable, a tester reported having successfully suspended himself in midair for a full minute.

Throughout the course, at least as much attention is devoted to surprises, failures, and lessons learned as to successes. It's all part of the process, Pickar says: Engineering is mostly trial and error, and students must learn to welcome both of those phases, not to fear them.

"They need to make mistakes in a safe environment," he grins, "before they do it for real."

For more on the course, read "Product Design for the Developing World."

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Dave Zobel
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Caltech Applied Physicist Amnon Yariv Awarded National Medal of Science

PASADENA, Calif., October 15, 2010—Amnon Yariv, the Martin and Eileen Summerfield Professor of Applied Physics and professor of electrical engineering—a pioneer in the field of optoelectronics—has been named one of 10 recipients of the National Medal of Science, the highest honor bestowed by the United States government on scientists.

Yariv was honored for "scientific and engineering contributions to photonics and quantum electronics that have profoundly impacted lightwave communications and the field of optics as a whole,"

according to a National Science Foundation (NSF) press release. (The NSF administers the National Medal of Science and its companion, the National Medal of Technology and Innovation, on behalf of the White House.)

"The extraordinary accomplishments of these scientists, engineers, and inventors are a testament to American industry and ingenuity," said President Barack Obama when announcing the awards. "Their achievements have redrawn the frontiers of human knowledge while enhancing American prosperity, and it is my tremendous pleasure to honor them for their important contributions."

Yariv's award brings the number of Caltech faculty and alumni recipients of the National Medal of Science to 55.

Yariv describes the thread of his research over the years as "fascination with light waves: learning how to generate them, manipulate them, and make them play new 'games.'" In the process, he developed mathematical theories widely used today to describe energy exchange among light waves, as well as experimental and fabrication techniques to demonstrate some of the resulting applications.

"A high point of my group's research," he says, "was the invention of the semiconductor Distributed Feedback Laser, which today powers the Internet's fiber-optic network." He also points to work he did with two colleagues to formulate the quantum theory of nonlinear optics. "Years after its development," he says, "it has become the starting point for the new and futuristic field of quantum communication." Current research in his group is aimed at getting a large number of lasers to collaborate and exchange information, thus realizing new functionalities.

"In addition to being the academic father of applied physics at Caltech, Amnon has personally mentored many of our most successful faculty members and continues to be one of the most constructive and imaginative forces within our division," says Ares Rosakis, the Theodore von Kármán Professor of Aeronautics, professor of mechanical engineering, and chair of the Division of Engineering and Applied Science. "We are indeed lucky to have him at Caltech."

Yariv earned his BS, MS, and PhD degrees from the University of California, Berkeley, in 1954, 1956, and 1958. He joined the Caltech faculty as an associate professor in 1964 and became a full professor in 1966. He was named the Summerfield Professor in 1996.

Yariv and his fellow medal recipients will receive their awards at a White House ceremony later this year.

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Lori Oliwenstein
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Capturing the Sun

With a prestigious Truman Fellowship at the Sandia National Laboratories, a Caltech graduate student continues his quest to create solar fuel.

William Chueh has traveled thousands of miles throughout the United States to pursue his passion of nature photography, often hiking deep into remote canyons to snap the perfect picture. But when it came time to choose a graduate school, he decided to stay put at his undergraduate alma mater, Caltech, summoning his love of nature and concern for the environment as a guide.

In 2005, Chueh, then a Caltech senior, applied to graduate school in the Institute's Division of Engineering and Applied Science, and in his application, he recalled an event that would inform his research path. Two years earlier, he wrote, he had made a trip to the iconic Yosemite Valley. He was anticipating pristine views, but what he found instead was a curtain of smog thrown up by thousands of cars and buses passing through. His goal as a graduate student, Chueh wrote, was to help fix that problem. Today, he's made significant progress toward that goal.

This month, after five years in the lab of Professor of Materials Science and Chemical Engineering Sossina Haile, Chueh wrapped up his doctoral research—work that included developing a novel method of using solar energy to generate fuel. That breakthrough recently earned him a prestigious Truman Fellowship at the Sandia National Laboratories in Livermore, California. Chueh is the first Caltecher to receive the three-year, $800,000 fellowship, which will give him the freedom and funding to pursue a line of research that may lead to crucial advances in the production of abundant, clean energy.

Chueh started his freshman year at Caltech shortly after 9/11, amid considerable discussion about America's critical need to wean itself off fossil fuels. One of the recommended areas of research concerned ways to improve energy conversion and storage, and Chueh got hooked on the subject.

"If you throw fuel and oxygen in an engine, it burns in an inefficient and dirty way," Chueh says. "But if you use electrochemistry and do it in a more controlled manner, then you will have better efficiency and lower emissions." During his senior year, he assisted in a research project led by Haile, who had been studying ways of improving fuel cells, which convert fuel into electricity through a chemical reaction.

One of the problems with many fuel cells concerns temperature.  Some can only operate at such high temperatures that they must be encased in expensive ceramic materials to withstand the heat, while those that can operate at close to room temperature need precious, scarce metals such as platinum to work. Another problem is that they need fuel—typically hydrogen derived from fossil fuels—to generate electricity.

Chueh holds three samples of metalized, thin-film cerium oxide, which he and Haile used to study the fundamental chemistry for generating fuel from the sun's heat.

Tackling the first problem, Haile had been investigating materials that would also allow fuel cells to work at lower temperatures. One of them, cerium oxide (CeO2), is derived from the element cerium—which is classified as a rare earth metal, but is actually as common as copper. Cerium oxide plays an important role in a car's catalytic converter, helping to turn smog-causing molecules into carbon dioxide.

Shortly after Chueh joined Haile's lab as a graduate student, he and Haile started talking about whether CeO2 could also play a role in using the heat of the sun to convert a chemical "cocktail," consisting primarily of carbon dioxide (CO2) and steam, into a gas mixture of carbon monoxide and hydrogen known as "synthesis gas." This "syngas," as it's commonly called, can then be converted into liquid fuels through a decades-old process involving a series of chemical reactions.

"I was pessimistic at first," Chueh says. For a while he held off on testing the idea, but at Haile's urging, he decided to run the necessary experiments during winter break in 2007, when everyone else in the lab was on vacation. "It worked right off the bat," Chueh says. "I'm very cautious, though, so I repeated it before I told her about it. We were all very excited by the results."

Currently, says Chueh, "I'm working on experiments to demonstrate that this is not just a laboratory curiosity, but a solution that could potentially work on a larger scale." The process could also be used in a variety of applications, including the production of fuel for transportation and for running factories.

Chueh took this photograph of the sensational fall colors in Yosemite Valley in 2006.

"William is a truly remarkable researcher, combining exceptional experimental talent with deep theoretical insight," says Haile. "This has allowed him to transform a loosely defined idea from a few sketches on a piece of paper to a meaningful scientific and technological breakthrough. I look forward to learning of his latest discoveries as he moves on to the next stage of his career."

At Sandia, a government-owned facility that develops technologies that support national security, Chueh will continue to study the cerium oxide–reaction to try to determine exactly what is happening at the molecular level while the catalyst is working. "Once we have a more detailed picture of that, we will be able to better understand why it works," he says, and possibly come up with ways to improve it.

Chueh says that he's "convinced that in the years to come, we'll see scaled-up plants that are actually producing a good amount of fuel from this kind of process. This system would work best in the desert, where there's lots of sun."

While Chueh acknowledges that there are numerous other solar research projects that could prove to be as beneficial as the cerium process, he says,  "Every system has its advantages and drawbacks. In the end, a solution to the energy problem will not come from a single technology but from a wide range of technologies. This gives consumers and policy makers one additional option."

As for the nature photography that started it all, Chueh didn't have much time for his hobby during graduate school, but he's looking forward to taking it up again.

"I'm hoping to go to the eastern Sierra in the fall when all the aspens turn yellow and then orange," he says. "In nature photography, I love finding order in chaos, and that's what we essentially do in science.

"Deep down, I have a great appreciation for the environment," Chueh says. "When I saw that smog-filled Yosemite Valley, that's when I thought, 'I've got to do something before all this gets wiped out.'"

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Mike Rogers
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Thad Vreeland Jr., 85

Thad Vreeland Jr., emeritus professor of materials science at the California Institute of Technology (Caltech), passed away August 9 in San Gabriel, California. He was 85 years old.

Vreeland—a member of Caltech's materials science program from its earliest days—was best known for his studies of the mechanical properties of materials, with an emphasis on how severely stressed materials deform plastically and permanently.

"His specialty was defects in materials—specifically dislocations, which are the agents of plastic deformation," says Brent Fultz, professor of materials science and applied physics at Caltech, and one of Vreeland's colleagues.

In the 1960s and '70s, Fultz says, Vreeland performed challenging experiments to measure how fast dislocations move in metal crystals; in the '80s, he studied how defects in thin layers of semiconductor materials are generated by ion bombardment or stresses. Vreeland's work in the 1990s included studies of how powders can be consolidated into bulk materials by subjecting them to strong mechanical shocks.

"Thad Vreeland took pride in laboratory technique and had both skill and style in building his own equipment, often frugally," says Fultz. "With the University of Pennsylvania's David Pope—then a Caltech graduate student—Vreeland designed and built a device for subjecting large crystals to pulsed torsional loads, and he built several x-ray diffractometers of unique design. Thad Vreeland's shock wave consolidation facility used the barrel of a field gun that he reinforced for even higher velocities."

Vreeland worked as a consultant for organizations such as Union Carbide, and collaborated with corporations and research institutions such as the McDonnell Douglas Research Laboratory on varied materials projects. He coauthored The Analysis of Stress and Deformation with Caltech's George W. Housner, who passed away in 2008.

"Thad was a great scientist and he interacted well with various researchers and engineers across campus," says Ares Rosakis, the Theodore von Kármán Professor of Aeronautics, professor of mechanical engineering, and chair of the Division of Engineering and Applied Science, "particularly with the solid mechanics group associated both with aeronautics and mechanical engineering."

Vreeland was born in 1924 and was a lifelong member of the Caltech community, receiving his BS in 1949, his MS in 1950, and his PhD in 1952. That same year, he was named a research fellow in engineering; he subsequently joined the Caltech faculty in 1954 as an assistant professor of mechanical engineering. Vreeland was a professor of materials science from 1968 until his retirement in 1991, whereupon he was named emeritus professor.

After his retirement, Vreeland spent a great deal of time in his Montana home—most of which he designed himself, says his wife, Mary Vreeland. "It was near West Yellowstone, which is the trout fishing center of the west," she adds. "Lots of Caltech faculty and students came up to fish with him."

In addition to Mary, Vreeland is survived by his children—Michael, Terry, and Janet—and two grandchildren, Theresa and Johanna.

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Lori Oliwenstein
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Two Caltech Scientists Named Among 2010 NIH Director's New Innovator Awardees

PASADENA, Calif.—As part of a National Institutes of Health (NIH) initiative to stimulate highly innovative research and support promising new scientific investigators, two scientists from the California Institute of Technology (Caltech) were named among the 2010 class of the NIH Director's New Innovator Award recipients.

Alexei Aravin, assistant professor of biology, and Changhuei Yang, associate professor of electrical engineering and bioengineering, were among those honored with the grants, which are meant to help new investigators take exceptional and innovative research ideas to the next level.

"NIH is pleased to be supporting early-stage investigators from across the country who are taking considered risks in a wide range of areas in order to accelerate research," says Francis S. Collins, director of the National Institutes of Health. "We look forward to the results of their work."

Yang and his research team will be pushing in a new research direction in biophotonics—the study of the interaction of time-reversed light with biological structures. When light hits the body's tissues, the light scatters, making visualizing structures under the skin extremely difficult. "A couple of years ago, my group experimentally demonstrated that it is possible to reduce tissue opacity"—make the tissues and their structures easier to see—"by time-reversing tissue light transmission," Yang explains. Put simply, they traced the paths of the scattered photons back through the tissues, showing that, by doing so, they could create images of what the light had encountered on its way in.

"We believe that this phenomenon holds a key to deep-tissue optical imaging and therapy," says Yang. "I am grateful for this New Innovator award, because it will allow my group to better understand the science and develop technologies that can capitalize on its advantages. If our work pans out well, it could lead the way to deep-tissue surgery without incision points, highly targeted optical-based cancer therapies, ultrasound imaging with chemical specificity, and better microscopy."

Yang received his BS, MS, and PhD from the Massachusetts Institute of Technology. He joined Caltech as an assistant professor of electrical engineering in 2003, became assistant professor of electrical engineering and bioengineering in 2004, and was named associate professor in 2009.

The research for which Aravin was singled out focuses on understanding the functions of small RNA—tiny snippets of ribonucleic acid that play a role in silencing genes through a pathway known as RNA interference. A few years ago, Aravin discovered a new class of small RNA that provides protection against a type of genomic parasite—the so-called transposable elements. He will use the New Innovator award to study the ways in which "small-RNA pathways can be programmed to modulate gene expression and cause heritable phenotypic changes"—changes to the proteins a cell makes, as well as to its other traits and characteristics. His goal? To use small RNA to develop tools and methodologies that can actively direct a cell down a particular developmental pathway.

"Achievement of these goals will be of great importance for both general science and medicine," says Aravin, "as it will provide insights into processes of development and lineage commitment and allow major advances to be made in medical applications such as stem cell technologies and anticancer therapies."

Aravin received his BS, MSc, and PhD from Moscow State University and joined the Caltech faculty in 2009.

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Lori Oliwenstein
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Jerrold E. Marsden, 68

Jerrold Eldon Marsden, the Carl F. Braun Professor of Engineering, Control and Dynamical Systems, and Applied and Computational Mathematics at Caltech, passed away on the evening of September 21, 2010, with his wife and daughter by his side. He was 68.

Marsden was one of the leading world experts in mathematical and theoretical mechanics. His work spanned a variety of fields, including fluid mechanics, geometric mechanics, elasticity, control theory, dynamical systems, and numerical methods. By focusing on geometric foundations, he was able to unite different disciplines, connecting mathematical theory with physical models and practical applications. His work has, consequently, influenced geometers and physicists alike. His research has led to advances in many areas, including spacecraft mission design, turbulence modeling, and the design of underwater vehicles. Marsden's influence was felt around the globe, in no small part because of his countless international collaborations.

"Jerry was an amazing intellectual, a gifted professor, and one of the finest colleagues that I have met," says Ares Rosakis, the Theodore von Kármán Professor of Aeronautics and professor of mechanical engineering, and chair of the Division of Engineering and Applied Science. "He was a great mentor to many of our Caltech students and our younger colleagues."

Born in Ocean Falls, British Columbia, Canada, Marsden graduated from the University of Toronto in 1965 with a BSc in mathematics. He received his PhD in applied mathematics in 1968 from Princeton University. He then joined the faculty at the University of California, Berkeley, before coming to Caltech in 1992 as a Fairchild Distinguished Scholar. He was appointed professor of control and dynamical systems in 1995, and in 2003, he was named the Carl F. Braun Professor. In 1992, he helped found the Fields Institute, a mathematical research institute at the University of Toronto, where he was a director until 1994.

Marsden was an accomplished educator and mentor, having written six undergraduate math textbooks, which are used worldwide, and 14 monographs, many of which are the definitive references in their fields. He has had more than 40 PhD students and postdocs. In 2006, Caltech's Graduate Student Council awarded him its Teaching and Mentoring Award.

He received numerous other awards that recognized his contributions as a researcher and educator: the Jeffrey-Williams Prize, the AMS-SIAM Norbert Wiener Prize, two Humboldt Prizes, a Fairchild Fellowship, the Max Planck Research Award, the SIAM von Neumann Prize, and the United Technologies Research Award. In 2006, he received an honorary doctorate from the University of Surrey. He will posthumously be awarded the 2010 Thomas K. Caughey Award this coming November in Vancouver.

He was elected a fellow of the Royal Society in 2006 and was a fellow of the Royal Society of Canada and the American Academy of Arts and Sciences.

He is survived by his wife, Barbara; his children, Christopher and Alison; grandchildren Eliza and Isaac; and sister Judy.

The family has requested that, in lieu of flowers, contributions be made to the Jerrold E. Marsden Scholarship Fund, which is an endowment that will be used to support students in Caltech's Department of Computing and Mathematical Sciences. Alternatively, contributions can be made to the Pasadena dog rescue, Mutts and Moms.

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Jon Weiner
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Caltech Engineer Named MacArthur Fellow

PASADENA, Calif.—John O. Dabiri, a fluid-dynamics expert at the California Institute of Technology (Caltech) whose studies of schooling fish have inspired new ideas for wind farming, was named a MacArthur Fellow today, and awarded a five-year, $500,000 "no strings attached" grant. Each year, the John D. and Catherine T. MacArthur Foundation awards the unrestricted fellowships—also known as "genius" grants—to individuals who show "exceptional creativity in their work and the prospect for still more in the future," according to the Foundation's website.

This year's crop of 23 Fellows includes stone carver Nicholas Benson and quantum astrophysicist Nergis Mavalvala; Dabiri joins the ranks of Caltech's previous MacArthur Fellows, including 2008 awardee Alexei Kitaev.

Unlike most MacArthur recipients—who are awakened with an early morning phone call announcing their prize—Dabiri, who is an associate professor of aeronautics and bioengineering at Caltech, received an email.

"The Foundation had one of the digits incorrect in my cell phone number, so they called the wrong guy," Dabiri says. "The email asked me to call the Foundation immediately, but since I had always heard that the winners receive a phone call, I assumed they just wanted my help getting in touch with a colleague. That's when I heard the good news—and I was completely shocked! Between proposal deadlines, papers, and preparing lecture notes, this wasn't at all on my radar."

Dabiri is the head of Caltech's Biological Propulsion Laboratory, where he and his colleagues examine the mechanics and dynamics of biological propulsion, which has applications for the design of new types of biologically inspired propulsion systems. Although Dabiri is notably a nonswimmer, and admits to sinking "like a stone" in the water, much of his work is focused on jellyfish, which he studies in a 40-meter-long, 8,000-gallon water tunnel at Caltech. Jellyfish can slice through the water with extreme efficiency and may generate high-powered jets when under attack. One outcome of this work has been the design of propellers that create vortex rings like those of jellyfish. In other research, Dabiri and his colleagues have developed a model that explains how some of the ocean's tiniest swimming animals may have a huge impact on large-scale ocean mixing.

Dabiri also is interested in developing new and better ways of harnessing wave and wind energy as power sources. "I became inspired by observations of schooling fish, and the suggestion that there is constructive hydrodynamic interference between the wakes of neighboring fish," he says. During these observations, Dabiri noticed that some of the vortices left behind by fish swimming in a school rotate clockwise, while others rotate counter-clockwise. He realized this could have relevance to wind farms, which are commonly hampered by a lack of space.

The large-propeller horizontal-axis wind turbines most commonly seen on wind farms require a substantial amount of land to perform properly; in contrast, vertical turbines, which use a vertical rotor, can be placed on smaller plots of land in a denser pattern. Dabiri and his colleagues determined that placing vertical-axis turbines in arrays with certain strategic configurations might allow the turbines to work more efficiently as a result of their relationship to others around them—just as in schools of fish.

Such configurations of vertical turbines are currently being put to the test on an experimental wind farm under construction in the high desert north of Los Angeles.

Dabiri, who holds a bachelor's degree from Princeton University, obtained a Master of Science degree in aeronautics from Caltech in 2003 and, in April 2005, a PhD in bioengineering with a minor in aeronautics from Caltech. In May 2005, he joined the Caltech faculty as an assistant professor; he was promoted to associate professor in 2009. In 2008, Dabiri was the recipient of an Office of Naval Research Young Investigator award for research in bioinspired propulsion, and was named one of Popular Science magazine's "Brilliant 10" young scientists to watch; in 2009, he was given a Presidential Early Career Award for Scientists and Engineers.

"We are proud and delighted that John has received this acknowledgment of his innovative approach to research and his engineering education and training at Caltech," says Ares J. Rosakis, the Theodore von Kármán Professor of Aeronautics, professor of mechanical engineering, and chair of the Division of Engineering and Applied Science.

"I'm extremely grateful for the MacArthur award, but it is the result of the efforts of many people," Dabiri says. "I've been blessed with generous mentors at every stage of life: from my parents, to my professors at Princeton, to Mory Gharib here at Caltech. It's also a credit to the students and postdocs in my lab, who work very hard on challenging and often risky research topics, and to my collaborators—especially biologists like Jack Costello at Providence College and Sean Colin at Roger Williams University—who gave me a deeper appreciation for the beautiful subtleties of jellyfish. I hope they all know how grateful I am."

"John has this extraordinary talent for making complex science and engineering issues simple through his deep understanding of these subjects," says Gharib, the Hans W. Liepmann Professor of Aeronautics, professor of bioinspired engineering, and Caltech's vice provost. "Getting ideas from jellyfish to design better propulsion systems requires an exceptionally creative mind. Receiving the MacArthur Fellowship award for his work on aquatic propulsion is a fantastic achievement for a nonswimmer."

"As for how I'll spend the money, I'm going to have to pray about that," Dabiri says. "This is an opportunity I never imagined I would have, and I want to make the most of it."

He does, however, have one idea: "I think I'll start with swimming lessons, so that I can finally get up close and personal with the jellyfish I've been studying from afar."

For more information on the 2010 MacArthur Fellows, visit the Foundation website at www.macfound.org.

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Kathy Svitil
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Caltech Receives $10 Million in Gifts to Help Launch New Terrestrial Hazard Center

Center will focus on developing innovative ways to reduce the risks and costs of natural hazards

PASADENA, Calif.-In an effort to find ways to minimize the damage caused by natural hazards, the California Institute of Technology (Caltech) has established the Terrestrial Hazard Observation and Reporting Center (THOR), funded by $6.7 million from Foster and Coco Stanback of Irvine, California, and $3.35 million from the Gordon and Betty Moore matching program.

THOR will have the unique mandate of bringing together-under one program-innovative efforts to reduce the risks and costs associated with natural hazards. The center will span two divisions at Caltech, Geological and Planetary Sciences (GPS) and Engineering and Applied Science (EAS).

The study of natural hazards and solutions is ordinarily undertaken in separate academic disciplines with little intellectual interaction. THOR will provide a new focal point that will unify these efforts and allow investigators to focus on critical societal issues.

"From the current flooding in Pakistan, to the recent earthquake in Haiti, to the constant threat of wildfires in our own backyard, we are consistently reminded of the devastating impact natural hazards can have on society," says Caltech president Jean-Lou Chameau. "Now, with the generous support of Foster and Coco Stanback, Caltech scientists and engineers will be able to study these critical issues in a unique interdisciplinary environment.  THOR will help communities around the world determine how to best prepare for, anticipate, and respond to various natural hazards, hopefully saving lives in the process." 

Natural hazards that will fall under THOR's purview include global climate change, earthquakes, tsunamis, landslides, wildfires, and extreme weather events such as droughts, among others.

By providing support for the development of techniques and physical inventions, THOR will focus on practical societal aspects of natural hazards and their public policy implications.

For instance, THOR may help guide the distribution of limited resources following a major hazard such as an earthquake or tsunami, or lead to early-warning systems.

"The interdisciplinary and interactive nature of engineering at Caltech allows us to translate scientific knowledge and discovery into applications with direct societal impact," says Ares Rosakis, the von Kármán Professor of Aeronautics, professor of mechanical engineering, and chair of the division of Engineering and Applied Science. "One of the areas of pioneering research and innovation made possible by THOR is seismo-engineering. The boundaries of seismo-engineering are fuzzy ones and lie exactly in the interface between seismology and earthquake engineering.  We are delighted to have the opportunity to explore these boundaries."

Caltech has a number of highly visible areas of expertise that already touch on natural-hazard issues, including the Seismological Laboratory, the Linde Center for Global Environmental Science, missions of the Caltech-managed Jet Propulsion Laboratory (JPL) that provide critical high-precision data on Earth's climate and environment, multiple studies supported by the Keck Institute for Space Studies (KISS) focused on future Earth-observing missions, and the Resnick Institute for Science, Energy, and Sustainability.   

"The THOR center will provide a unique platform for collaboration among scientists, students, and policymakers, empowering them with the extensive resources of Caltech and the Jet Propulsion Laboratory," says THOR donor Foster Stanback. "By linking our eyes in the sky with the many eyes on the ground, we will be far better prepared to anticipate, mitigate, and eliminate many environmental hazards."

THOR's attention and resources will be applied in several ways, including the dissemination of the results of work supported by THOR; supporting efforts to transfer ideas and technologies that show promise of practical implementation; and prioritizing, seeding, and nurturing ideas encompassing research activities, along with the invention of technologies.

"THOR will give faculty in GPS and EAS the opportunity to develop innovative new ways to help mitigate the consequences and costs of the natural hazards society faces, from climate change to earthquakes to water scarcity," says Ken Farley, the W.M. Keck Foundation Professor of Geochemistry and chair of the division of Geological and Planetary Sciences. "This very applied research is difficult to support from federal sources, so my hope is that the gift will catalyze entirely new endeavors. THOR will also allow us to bring to our educational program a new focus on the societal and policy implications and relevance of our work."

The center will be housed within the newly renovated Linde + Robinson Laboratory on the Caltech campus.

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Jon Weiner
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