Tuesday, May 26, 2015 to Friday, May 29, 2015
Center for Student Services 360 (Workshop Space) – Center for Student Services

CTLO Presents Ed Talk Week 2015

Ditch Day? It’s Today, Frosh!

Today we celebrate Ditch Day, one of Caltech's oldest traditions. During this annual spring rite—the timing of which is kept secret until the last minute—seniors ditch their classes and vanish from campus. Before they go, however, they leave behind complex, carefully planned out puzzles and challenges—known as "stacks"—designed to occupy the underclassmen and prevent them from wreaking havoc on the seniors' unoccupied rooms.

Follow the action on Caltech's Facebook, Twitter, and Instagram pages as the undergraduates tackle the puzzles left for them to solve around campus. Join the conversation by sharing your favorite Ditch Day memories and using #CaltechDitchDay in your tweets and postings.

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Watching Paint Dry and Colors Fade: The Intersection of Art and Science

Watson Lecture Preview

Conserving a museum's holdings is a blend of art and science. Analytical chemists have explained why a dramatic sky disappeared from Winslow Homer's For to Be a Farmer's Boy. Materials scientists have unearthed the sources of color in ancient Chinese jades. Environmental engineers have uncovered the reasons behind the faded brilliance of Georges Seurat's A Sunday on La Grande Jatte.

On Wednesday, May 20, at 8 p.m. in Caltech's Beckman Auditorium, Katherine T. Faber, the Simon Ramo Professor of Materials Science at Caltech, will examine how science serves art in a museum setting, and discuss how bridges to universities can be built.

 

Q: What do you do?

A: I am a materials scientist who focuses on the mechanical behavior of brittle materials. Ceramic materials are especially attractive for use at very high temperatures, such as those needed for energy-related applications—engine components, catalyst supports, or coatings for turbines in aerospace or power generation.

And when I say "mechanical behavior," I'm largely interested in how materials fracture. I'm pretty fortunate to be able to break things for a living. But I have also discovered through the years that some of the materials and structures that I want to study don't exist. That has forced me to move into ceramic processing as well. That way my students and I can understand the link between how the materials are made and how they respond.

Our recent work has focused on porous materials. Historically, one would not want pores in brittle materials, because they act as flaws, and therefore as sources of failure. More recently, porosity is desirable in ceramics, for high-temperature filters or for biomedical scaffolds that allow cell or bone ingrowth, to name just two examples.

 

Q: How does that relate to art conservation, which is the subject of your talk?

A: Conservation studies have actually become an important part of my career. Objects of cultural heritage are made up of the same materials that we study as materials scientists. The phenomena that occur in cultural heritage materials are of particular interest—one needs to understand degradation, such as fading or cracking, in order to preserve these objects. The merit of these studies reaches beyond the art community. We all benefit from these investigations. So will our children, if we continue to study and protect our cultural heritage.

Engineering disciplines are generally very forward thinking and future-oriented. We say, "What materials can we make that will improve our future?" But it is also of value to take our knowledge of materials and look back. One aspect of this art-related work that has been appealing to students is the realization that the expertise that they are developing can be used to solve many different kinds of problems. It's not just about the next photovoltaic or the next superalloy—their talents and skills can be put to use in technical art history. Ultimately, I would like to develop partnerships here in Southern California that will offer Caltech students the same opportunities that the students at Northwestern University have had with the Art Institute of Chicago. It's simply a matter of finding the right partners in the broad array of museums we have here.

 

Q: How did you get into this line of work?

A: Quite by chance. About 12 years ago, I was approached by staff from the Art Institute of Chicago, which had just been given funds to hire its very first conservation scientist. The museum had a very large conservation department, but it did not have a PhD-level scientist on board. The staff was trying to anticipate the needs of this person, who had yet to be named. They were hoping to identify contacts in the academic community for their future hire, and they had heard about my department's reputation. I was the chair of Northwestern's Department of Materials Science and Engineering at the time, so I was the natural person to visit. When asked if we might be a good link for their scientist, my response was an immediate "Yes!"

And indeed, a year later the Art Institute hired a fantastic conservation scientist, Francesca Casadio, and we started to work together immediately. We've collaborated on ancient Chinese jades and Meissen ceramics. I also became the matchmaker, if you will, who linked other engineering faculty at Northwestern to the Art Institute. In 2013, Francesca and I went on to found the Center for Scientific Studies in the Arts, a partnership funded by the Andrew W. Mellon Foundation, extending our research to museums around the U.S. But it was all serendipity.

 

Named for the late Caltech professor Earnest C. Watson, who founded the series in 1922, the Watson Lectures present Caltech and JPL researchers describing their work to the public. Many past Watson Lectures are available online at Caltech's iTunes U site.

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Watching Paint Dry and Colors Fade
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Caltech Students Named Goldwater Scholars

Two Caltech students, Saaket Agrawal and Paul Dieterle, have been awarded Barry M. Goldwater scholarships for the 2015–16 academic year.

The Barry Goldwater Scholarship and Excellence in Education Program was established by Congress in 1986 to award scholarships to college students who intend to pursue research careers in science, mathematics, and engineering.

Saaket Agrawal is a sophomore from El Dorado Hills, California, majoring in chemistry. Under Greg Fu, the Altair Professor of Chemistry, Agrawal works on nickel-catalyzed cross coupling, a powerful method for making carbon-carbon bonds. Specifically, Agrawal conducts mechanistic studies on these reactions, which involves elucidating the pathway through which they occur. After Caltech, he plans to pursue a PhD research program in organometallic chemistry—the combination of organic (carbon-based) and inorganic chemistry—and ultimately hopes teach at the university level.

"Caltech is one of the best places in the world to study chemistry. The faculty were so willing to take me on, even as an undergrad, and treat me like a capable scientist," Agrawal says. "That respect, and the ability to do meaningful work, has motivated me."

Paul Dieterle is a junior from Madison, Wisconsin, majoring in applied physics. He works with Oskar Painter, the John G. Braun Professor of Applied Physics, studying quantum information science.

"The quantum behavior of atoms has been studied for decades. We are researching the way macroscopic objects behave in a quantum mechanical way in order to manipulate them into specific quantum states," Dieterle says. Painter's group is studying how to use macroscopic mechanical objects to transform quantized electrical signals into quantized optical signals as part of the larger field of quantum computing, a potential next generation development in the field.

"The power of quantum computing would be immense," says Dieterle, who would like to attend graduate school to study quantum information science. "We could simulate incredibly complex things, like particles at the edge of a black hole. Participating in this physics revolution is so exciting."

Agrawal and Dieterle bring the number of Caltech Goldwater Scholars to 22 in the last decade.

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New Thin, Flat Lenses Focus Light as Sharply as Curved Lenses

Lenses appear in all sorts of everyday objects, from prescription eyeglasses to cell-phone cameras. Typically, lenses rely on a curved shape to bend and focus light. But in the tight spaces inside consumer electronics and fiber-optic systems, these rounded lenses can take up a lot of room. Over the last few years, scientists have started crafting tiny flat lenses that are ideal for such close quarters. To date, however, thin microlenses have failed to transmit and focus light as efficiently as their bigger, curved counterparts.

Caltech engineers have created flat microlenses with performance on a par with conventional, curved lenses. These lenses can be manufactured using industry-standard techniques for making computer chips, setting the stage for their incorporation into electronics such as cameras and microscopes, as well as in novel devices.

"The lenses we use today are bulky," says Amir Arbabi, a senior researcher in the Division of Engineering and Applied Science, and lead author of the paper. "The structure we have chosen for these flat lenses can open up new areas of application that were not available before."

The research, led by Andrei Faraon (BS '04), assistant professor of applied physics and material science, appears in the May 7 issue of Nature Communications.

The new lens type is known as a high-contrast transmitarray. Made of silicon, the lens is just a millionth of a meter thick, or about a hundredth of the diameter of a human hair, and it is studded with silicon "posts" of varying sizes. When imaged under a scanning electron microscope, the lens resembles a forest cleared for timber, with only stumps (the posts) remaining. Depending on their heights and thicknesses, the posts focus different colors, or wavelengths, of light.

A lens focuses light or forms an image by delaying for varying amounts of time the passage of light through different parts of the lens. In curved glass lenses, light takes longer to travel through the thicker parts of the lens than through the thinner parts. On the flat lens, these delays are achieved by the silicon posts, which trap and delay the light for an amount of time that depends on the diameter of the posts. With careful placement of these differently sized posts on the lens, the researchers can guide incident light as it passes through the lens to form a curved wavefront, resulting in a tightly focused spot.

The Caltech researchers found that their flat lenses focus as much as 82 percent of infrared light passing through them. By comparison, previous studies have found that metallic flat lenses have efficiencies of only around a few percent, in part because their materials absorb some incident light.

Although curved glass lenses can focus nearly 100 percent of the light that reaches them, they usually require sophisticated designs with nonspherical surfaces that can be difficult to polish. On the other hand, the design of the flat lenses can be modified depending upon the exact application for which the lenses are needed, simply by changing the pattern of the silicon nanoposts. This flexibility makes them attractive for commercial and industrial use, the researchers say. "You get exceptional freedom to design lenses for different functionalities," says Arbabi.

A limitation of flat lenses is that each lens can only focus a narrow set of wavelengths, representing individual colors of the spectrum. These monochromatic lenses could find application in devices such as a night-vision camera, which sees in infrared over a narrow wavelength range. More broadly, they could be used in any optical device involving lasers, as lasers emit only a single color of light.

Multiple monochromatic lenses could be used to deliver multicolor images, much as television and computer displays employ combinations of the colors red, green, and blue to produce a rainbow of hues. Because the microlenses are so small, integrating them in optical systems would take up little space compared to the curved lenses now utilized in cameras or microscopes.

Although the lenses currently are expensive to manufacture, it should be possible to produce thousands at once using photolithography or nanoimprint lithography techniques, the researches say. In these common, high-throughput manufacturing techniques, a stamp presses into a polymer, leaving behind a desired pattern that is then transferred into silicon through dry etching of silicon in a plasma.

"For consumer applications, the current price point of flat lenses is not good, but the performance is," says Faraon. "Depending on how many of lenses you are making, the price can drop down rapidly."

The paper is entitled "Subwavelength-thick lenses with high numerical apertures and large efficiency based on high-contrast transmitarrays." In addition to Arbabi and Faraon, other Caltech coauthors include graduate student Yu Horie, senior Alexander Ball, and Mahmood Bagheri, a microdevices engineer at JPL. The work was supported by the Caltech/JPL President's and Director's Fund and the Defense Advanced Research Projects Agency. Alexander Ball was supported by a Summer Undergraduate Research Fellowship at Caltech. The device nanofabrication was performed in the Kavli Nanoscience Institute at Caltech.

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Monday, May 18, 2015
Brown Gymnasium – Scott Brown Gymnasium

Jupiter’s Grand Attack

JCAP Receives a 5-Year, $75M Funding Renewal

On Monday, April 27, the Department of Energy (DOE) announced a five-year, $75 million renewal of the Joint Center for Artificial Photosynthesis (JCAP). JCAP's mission is to explore the science and technology of artificial photosynthesis to harness solar energy for the production of fuel.

JCAP is the nation's largest research program dedicated to the development of an artificial solar-fuel generation technology. Established in 2010 as a DOE Energy Innovation Hub, JCAP aims to create a low-cost generator to make fuel from sunlight 10 times more efficiently than plants. Such a breakthrough would have the potential to reduce our country's dependence on oil and enhance energy security.

The Hub is directed by Caltech, but it has its primary sites both at Lawrence Berkeley National Laboratory (LBNL) and at Caltech. JCAP brings together more than 150 scientists and engineers from Caltech and LBNL, and also draws on the expertise and capabilities of key partners at UC Irvine, UC San Diego, and the SLAC National Accelerator Laboratory at Stanford.

The funding renewal announcement was made at LBNL by Franklin Orr, under secretary for science and energy at DOE.

"JCAP's work to produce fuels from sunlight and carbon dioxide holds the promise of a potentially revolutionary technology that would put America on the path to a low-carbon economy," said Orr in a DOE press release. "While the scientific challenges of producing such fuels are considerable," the released noted, "JCAP will capitalize on state-of-the-art capabilities developed during its initial five years of research, including sophisticated characterization tools and unique automated high-throughput experimentation that can quickly make and screen large libraries of materials to identify components for artificial photosynthesis systems."   

"We are honored and delighted to receive renewed support from the Department of Energy for JCAP," says JCAP director Harry A. Atwater, Howard Hughes Professor of Applied Physics and Materials Science at Caltech. "Thanks to this renewal, JCAP will continue to push the scientific frontiers of artificial photosynthesis, with an emphasis on selective carbon dioxide reduction under mild temperature and pressure conditions. Carbon dioxide reduction is at the core of natural photosynthesis, and understanding the science and technology of this reaction is also central to society's efforts to mitigate carbon dioxide emission. It is an enormous challenge, but just the sort of problem that is worthy of sustained scientific investment. We are excited for the work ahead."

In its first five years of research, JCAP has made significant advances in a number of areas, including the automated and rapid discovery and characterization of new catalysts and light absorbers, the development of techniques for protecting the light-absorbing components in solar-fuels generators, and the creation of experimental protocols for objective evaluations of the activity and stability of materials. All of these technologies are critical to the development of solar-driven water splitting and the reduction of carbon dioxide to produce fuel.

For more information about JCAP, please visit http://solarfuelshub.org/.

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Tuesday, May 19, 2015
Guggenheim 101 (Lees-Kubota Lecture Hall) – Guggenheim Aeronautical Laboratory

Science in a Small World - Short Talks

Tuesday, May 19, 2015
Dabney Hall, Garden of the Associates – The Garden of the Associates

Science in a Small World - Poster Session #2

Tuesday, May 19, 2015
Dabney Hall, Garden of the Associates – The Garden of the Associates

Science in a Small World - Poster Session #1

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