Artificial Leaf Harnesses Sunlight for Efficient Fuel Production

Generating and storing renewable energy, such as solar or wind power, is a key barrier to a clean-energy economy. When the Joint Center for Artificial Photosynthesis (JCAP) was established at Caltech and its partnering institutions in 2010, the U.S. Department of Energy (DOE) Energy Innovation Hub had one main goal: a cost-effective method of producing fuels using only sunlight, water, and carbon dioxide, mimicking the natural process of photosynthesis in plants and storing energy in the form of chemical fuels for use on demand. Over the past five years, researchers at JCAP have made major advances toward this goal, and they now report the development of the first complete, efficient, safe, integrated solar-driven system for splitting water to create hydrogen fuels.

"This result was a stretch project milestone for the entire five years of JCAP as a whole, and not only have we achieved this goal, we also achieved it on time and on budget," says Caltech's Nate Lewis, George L. Argyros Professor and professor of chemistry, and the JCAP scientific director.

The new solar fuel generation system, or artificial leaf, is described in the August 27 online issue of the journal Energy and Environmental Science. The work was done by researchers in the laboratories of Lewis and Harry Atwater, director of JCAP and Howard Hughes Professor of Applied Physics and Materials Science.

"This accomplishment drew on the knowledge, insights and capabilities of JCAP, which illustrates what can be achieved in a Hub-scale effort by an integrated team," Atwater says. "The device reported here grew out of a multi-year, large-scale effort to define the design and materials components needed for an integrated solar fuels generator."


Solar Fuels Prototype in Operation
A fully integrated photoelectrochemical device performing unassisted solar water splitting for the production of hydrogen fuel. Credit: Erik Verlage and Chengxiang Xiang/Caltech

The new system consists of three main components: two electrodes—one photoanode and one photocathode—and a membrane. The photoanode uses sunlight to oxidize water molecules, generating protons and electrons as well as oxygen gas. The photocathode recombines the protons and electrons to form hydrogen gas. A key part of the JCAP design is the plastic membrane, which keeps the oxygen and hydrogen gases separate. If the two gases are allowed to mix and are accidentally ignited, an explosion can occur; the membrane lets the hydrogen fuel be separately collected under pressure and safely pushed into a pipeline.

Semiconductors such as silicon or gallium arsenide absorb light efficiently and are therefore used in solar panels. However, these materials also oxidize (or rust) on the surface when exposed to water, so cannot be used to directly generate fuel. A major advance that allowed the integrated system to be developed was previous work in Lewis's laboratory, which showed that adding a nanometers-thick layer of titanium dioxide (TiO2)—a material found in white paint and many toothpastes and sunscreens—onto the electrodes could prevent them from corroding while still allowing light and electrons to pass through. The new complete solar fuel generation system developed by Lewis and colleagues uses such a 62.5-nanometer-thick TiO2 layer to effectively prevent corrosion and improve the stability of a gallium arsenide–based photoelectrode.

Another key advance is the use of active, inexpensive catalysts for fuel production. The photoanode requires a catalyst to drive the essential water-splitting reaction. Rare and expensive metals such as platinum can serve as effective catalysts, but in its work the team discovered that it could create a much cheaper, active catalyst by adding a 2-nanometer-thick layer of nickel to the surface of the TiO2. This catalyst is among the most active known catalysts for splitting water molecules into oxygen, protons, and electrons and is a key to the high efficiency displayed by the device.

The photoanode was grown onto a photocathode, which also contains a highly active, inexpensive, nickel-molybdenum catalyst, to create a fully integrated single material that serves as a complete solar-driven water-splitting system.

A critical component that contributes to the efficiency and safety of the new system is the special plastic membrane that separates the gases and prevents the possibility of an explosion, while still allowing the ions to flow seamlessly to complete the electrical circuit in the cell. All of the components are stable under the same conditions and work together to produce a high-performance, fully integrated system. The demonstration system is approximately one square centimeter in area, converts 10 percent of the energy in sunlight into stored energy in the chemical fuel, and can operate for more than 40 hours continuously.

"This new system shatters all of the combined safety, performance, and stability records for artificial leaf technology by factors of 5 to 10 or more ," Lewis says.

"Our work shows that it is indeed possible to produce fuels from sunlight safely and efficiently in an integrated system with inexpensive components," Lewis adds, "Of course, we still have work to do to extend the lifetime of the system and to develop methods for cost-effectively manufacturing full systems, both of which are in progress."

Because the work assembled various components that were developed by multiple teams within JCAP, coauthor Chengxiang Xiang, who is co-leader of the JCAP prototyping and scale-up project, says that the successful end result was a collaborative effort. "JCAP's research and development in device design, simulation, and materials discovery and integration all funneled into the demonstration of this new device," Xiang says.

These results are published in a paper titled "A monolithically integrated, intrinsically safe, 10% efficient, solar-driven water-splitting system based on active, stable earth-abundant electrocatalysts in conjunction with tandem III-V light absorbers protected by amorphous TiO2 films." In addition to Lewis, Atwater, and Xiang, other Caltech coauthors include graduate student Erik Verlage, postdoctoral scholars Shu Hu and Ke Sun, material processing and integration research engineer Rui Liu, and JCAP mechanical engineer Ryan Jones. Funding was provided by the Office of Science at the U.S. Department of Energy, and the Gordon and Betty Moore Foundation.

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Caltech Chemists Solve Major Piece of Cellular Mystery

Team determines the architecture of a second subcomplex of the nuclear pore complex

Not just anything is allowed to enter the nucleus, the heart of eukaryotic cells where, among other things, genetic information is stored. A double membrane, called the nuclear envelope, serves as a wall, protecting the contents of the nucleus. Any molecules trying to enter or exit the nucleus must do so via a cellular gatekeeper known as the nuclear pore complex (NPC), or pore, that exists within the envelope.

How can the NPC be such an effective gatekeeper—preventing much from entering the nucleus while helping to shuttle certain molecules across the nuclear envelope? Scientists have been trying to figure that out for decades, at least in part because the NPC is targeted by a number of diseases, including some aggressive forms of leukemia and nervous system disorders such as a hereditary form of Lou Gehrig's disease. Now a team led by André Hoelz, assistant professor of biochemistry at Caltech, has solved a crucial piece of the puzzle.

In February of this year, Hoelz and his colleagues published a paper describing the atomic structure of the NPC's coat nucleoporin complex, a subcomplex that forms what they now call the outer rings (see illustration). Building on that work, the team has now solved the architecture of the pore's inner ring, a subcomplex that is central to the NPC's ability to serve as a barrier and transport facilitator. In order to the determine that architecture, which determines how the ring's proteins interact with each other, the biochemists built up the complex in a test tube and then systematically dissected it to understand the individual interactions between components. Then they validated that this is actually how it works in vivo, in a species of fungus.

For more than a decade, other researchers have suggested that the inner ring is highly flexible and expands to allow large macromolecules to pass through. "People have proposed some complicated models to explain how this might happen," says Hoelz. But now he and his colleagues have shown that these models are incorrect and that these dilations simply do not occur.

"Using an interdisciplinary approach, we solved the architecture of this subcomplex and showed that it cannot change shape significantly," says Hoelz. "It is a relatively rigid scaffold that is incorporated into the pore and basically just sits as a decoration, like pom-poms on a bicycle. It cannot dilate."

The new paper appears online ahead of print on August 27 in Science Express. The four co-lead authors on the paper are Caltech postdoctoral scholars Tobias Stuwe, Christopher J. Bley, and Karsten Thierbach, and graduate student Stefan Petrovic.


Crystal Structure of Fungal Channel Nucleoporin Complex
This video features a rotating three-dimensional crystal structure of the fungal channel nucleoporin complex bound to the adaptor nucleoporin Nic96. This interaction is the complex's sole site of attachment to the rest of the inner ring of the NPC. The channel nucleoporin complex borders the central transport channel and fills it with filamentous structures (phenylalanine-glycine repeats) that form a diffusion barrier and provide docking sites for proteins that ferry molecules across the nuclear envelope. Credit: Andre Hoelz/Caltech and Science

Together, the inner and outer rings make up the symmetric core of the NPC, a structure that includes 21 different proteins. The symmetric core is so named because of its radial symmetry (the two remaining subcomplexes of the NPC are specific to either the side that faces the cell's cytoplasm or the side that faces the nucleus and are therefore not symmetric). Having previously solved the structure of the coat nucleoporin complex and located it in the outer rings, the researchers knew that the remaining components that are not membrane anchored must make up the inner ring.

They started solving the architecture by focusing on the channel nucleoporin complex, or channel, which lines the central transport channel and is made up of three proteins, accounting for about half of the inner ring. This complex produces filamentous structures that serve as docking sites for specific proteins that ferry molecules across the nuclear envelope.

The biochemists employed bacteria to make the proteins associated with the inner ring in a test tube and mixed various combinations until they built the entire subcomplex. Once they had reconstituted the inner ring subcomplex, they were able to modify it to investigate how it is held together and which of its components are critical, and to determine how the channel is attached to the rest of the pore.

Hoelz and his team found that the channel is attached at only one site. This means that it cannot stretch significantly because such shape changes require multiple attachment points. Hoelz notes that a new electron microscopy study of the NPC published in 2013 by Martin Beck's group at the European Molecular Biology Laboratory (EMBL) in Heidelberg, Germany, indicated that the central channel is bigger than previously thought and wide enough to accommodate even the largest cargoes known to pass through the pore.

When the researchers introduced mutations that effectively eliminated the channel's single attachment, the complex could no longer be incorporated into the inner ring. After proving this in the test tube, they also showed this to be true in living cells.

"This whole complex is a very complicated machine to assemble. The cool thing here is that nature has found an elegant way to wait until the very end of the assembly of the nuclear pore to incorporate the channel," says Hoelz. "By incorporating the channel, you establish two things at once: you immediately form a barrier and you generate the ability for regulated transport to occur through the pore." Prior to the channel's incorporation, there is simply a hole through which macromolecules can freely pass.

Next, Hoelz and his colleagues used X-ray crystallography to determine the structure of the channel nucleoporin subcomplex bound to the adaptor nucleoporin Nic96, which is its only nuclear pore attachment site. X-ray crystallography involves shining X-rays on a crystallized sample and analyzing the pattern of rays reflected off the atoms in the crystal. Because the NPC is a large and complex molecular machine that also has many moving parts, they used an engineered antibody to essentially "superglue" many copies of the complex into place to form a nicely ordered crystalline sample. Then they analyzed hundreds of samples using Caltech's Molecular Observatory—a facility developed with support from the Gordon and Betty Moore Foundation that includes an automated X-ray beam line at the Stanford Synchrotron Radiation Laboratory that can be controlled remotely from Caltech—and the GM/CA beam line at the Advanced Photon Source at the Argonne National Laboratory. Eventually, they were able to determine the size, shape, and position of all the atoms of the channel nucleoporin subcomplex and its location within the full NPC.

"The crystal structure nailed it," Hoelz says. "There is no way that the channel is changing shape. All of that other work that, for more than 10 years, suggested it was dilating was wrong."

The researchers also solved a number of crystal structures from other parts of the NPC and determined how they interact with components of the inner ring. In doing so they demonstrated that one such interaction is critical for positioning the channel in the center of the inner ring. They found that exact positioning is needed for the proper export from the nucleus of mRNA and components of ribosomes, the cell's protein-making complexes, rendering it critical in the flow of genetic information from DNA to mRNA to protein.

Hoelz adds that now that the architectures of the inner and outer rings of the NPC are known, getting an atomic structure of the entire symmetric core is "a sprint to the summit."

"When I started at Caltech, I thought it might take another 10, 20 years to do this," he says. "In the end, we have really only been working on this for four and a half years, and the thing is basically tackled. I want to emphasize that this kind of work is not doable everywhere. The people who worked on this are truly special, talented, and smart; and they worked day and night on this for years."

Ultimately, Hoelz says he would like to understand how the NPC works in great detail so that he might be able to generate therapies for diseases associated with the dysfunction of the complex. He also dreams of building up an entire pore in the test tube so that he can fully study it and understand what happens as it is modified in various ways. "Just as they did previously when I said that I wanted to solve the atomic structure of the nuclear pore, people will say that I'm crazy for trying to do this," he says. "But if we don't do it, it is likely that nobody else will."

The paper, "Architecture of the fungal nuclear pore inner ring complex," had a number of additional Caltech authors: Sandra Schilbach (now of the Max Planck Institute of Biophysical Chemistry), Daniel J. Mayo, Thibaud Perriches, Emily J. Rundlet, Young E. Jeon, Leslie N. Collins, Ferdinand M. Huber, and Daniel H. Lin. Additional coauthors include Marcin Paduch, Akiko Koide, Vincent Lu, Shohei Koide, and Anthony A. Kossiakoff of the University of Chicago; and Jessica Fischer and Ed Hurt of Heidelberg University.

 

 

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High School Students Visit for Women in STEM Preview Day

On Friday, August 7, 104 female high school seniors and their families visited Caltech for the fourth annual Women in STEM (WiSTEM) Preview Day, hosted by the undergraduate admissions office. The event was designed to explore the accomplishments and continued contributions of Caltech women in the disciplines of science, technology, engineering, and mathematics (STEM).

The day opened with a keynote address by Marianne Bronner, the Albert Billings Ruddock Professor of Biology and executive officer for neurobiology. Bronner, who studies the development of the central nervous system, spoke about her experiences in science and at Caltech.

"Caltech is an exciting place to be. It's a place where you can be creative and think outside the box," she said. "My advice to you would be to try different things, play around, and do what makes you happy." Bronner ended her address by noting the pleasure she takes in mentoring young scientists, and especially young women. "I was just like you," she said.

Over the course of the day, students and their families attended panels on undergraduate research opportunities and participated in social events where current students shared their experiences of Caltech life. They also listened to presentations from female scientists and engineers of the Jet Propulsion Laboratory.

"I really love science, and it's so exciting to be around all of these other people who share that," says Sydney Feldman, a senior from Maryland. "I switched around my whole summer visit schedule to come to this event and I'm having such a great time."

The annual event began four years ago with the goal of encouraging interest in STEM in high school women and ultimately increasing applications to Caltech by female candidates. In 2009, a U.S. Department of Commerce study showed that women make up 24 percent of the STEM workforce and hold a disproportionately low share of undergraduate degrees in STEM fields.

"Women are seriously underrepresented in these fields," says Caltech admissions counselor and WiSTEM coordinator Abeni Tinubu. "Our event really puts emphasis on how Caltech supports women on campus, and we want to show prospective students that."

This year, the incoming freshman class is a record 47 percent female students. "This is hugely exciting," says Jarrid Whitney, the executive director of admissions and financial aid. "We've been working hard toward our goal of 50 percent women, and it is clearly paying off thanks to the support of President Rosenbaum and the overall Caltech community."

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Science for the Community

On the grounds of San Marino's Huntington Library, Art Collections, and Botanical Gardens—to the north of the Chinese Gardens, in the private, half-acre Huntington Ranch area—nearly two dozen middle- and high-school students have been spending this summer measuring the levels of nitrogen in the soils around them to help the ranch determine whether its soil is up to the challenge of growing an urban garden.

This hands-on research experience is part of the Community Science Academy @ Caltech, which is affiliated with Caltech's Center for Teaching, Learning, and Outreach (CTLO). The 23 first-timers in what is called CSA 1 are studying biological systems at the ranch; a similar number of continuing students, in CSA 2, are studying engineering and programming, and are building their own scientific instruments.

The program runs three days a week for six weeks. For CSA 1 students, it began on June 15 with soil sampling; by July 24, when it ends, students will have designed and performed their own experiments.

CSA@Caltech is now in its second year. It initially was funded with support from a National Institutes of Health Director's Pioneer Award to Caltech Professor of Biology Bruce Hay. In addition, the Pasadena Educational Foundation and the Siemens Foundation currently provide support for scholarships that allow all students from the Pasadena Unified School District to attend the program free of charge.

The students start most days with lectures by members of the Caltech staff. Every student is issued an iPad and keyboard for note taking and fieldwork. This technology allows the lectures to become interactive presentations using software that allows constant feedback between teacher and student. They spend much of their time at the CTLO on the Caltech campus, for talks on topics including soil and water quality, pest control, environmental monitoring, and remote sensing. They also work in the undergraduate teaching labs in Caltech's Divisions of Chemistry and Chemical Engineering and Biology and Biological Engineering for lessons on plant processing and bacterial detection, respectively.

At the Huntington Library, students apply in an outdoor setting what they have learned and practiced in Caltech classrooms and labs. For example, they gather soil samples from gardens and water samples from lily ponds for nitrate and ammonia testing; they conduct experiments on ant behavior; and they design and build sensor-carrying remote-controlled powered kites, which they fly over the Library grounds.

"These hands-on methods are critical for teaching students about the collaborative nature of science, the system of trial and error, and the importance of following protocols in scientific experimentation and analysis," says James Maloney (MS '06), one of the two codirectors of the CSA@Caltech program. Even while the students are getting what may well be their first exposure to research, they are also making a serious contribution to the Huntington's understanding of the ranch's viability as an urban garden. The ranch was originally a gravel parking lot, notes ranch coordinator Kyra Saegusa. It took six years for the soil to be rebuilt with sheets of mulch. The question now is whether it is ready for growing fruits and vegetables.

If the shouts of "I got a worm!" from one 13-year-old field worker are any indication, the soil restoration is certainly moving in the right direction.

The ultimate goal of CSA@Caltech—to promote STEM (science, technology, engineering, and mathematics) in secondary education and to help create the next generation of scientists—is further buttressed by tours of Caltech labs, where researchers such as Sarah Reisman, professor of chemistry, talked to the CSA@Caltech students about life as a scientist. Some of the students have already chosen areas in which they think they would like to specialize: for instance, Eris, a ninth grader from Blair High School in CSA 2, wants to study engineering and chemistry; Brandon, a CSA 2 ninth grader from Pasadena High School, wants to go into theoretical physics; and CSA 1 student Connor, an eighth grader from Sierra Madre Middle School, wants to be an aerospace engineer.

Building on this success, CSA@Caltech plans to add a third year of study next summer and continue their development of new educational technologies. "Our goal is to make high-quality science accessible to all," says CSA@Caltech codirector Julius Su (BS '98, BS '99, PhD '07).

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$100 Million Gift from Gordon and Betty Moore Will Bolster Graduate Fellowships

Trustees Gordon (PhD '54) and Betty Moore have pledged $100 million to Caltech, the second-largest single contribution in the Institute's history. With this gift, they have created a permanent endowment and entrusted the choice of how to direct the funds to the Institute's leadership—providing lasting resources coupled with uncommon freedom.

"Those within the Institute have a much better view of what the highest priorities are than we could have," Intel Corporation cofounder Gordon Moore explains. "We'd rather turn the job of deciding where to use resources over to Caltech than try to dictate it from outside."

Applying the Moores' donation in a way that will strengthen the Institute for generations to come, Caltech's president and provost have decided to dedicate the funds to fellowships for graduate students.

"Gordon and Betty Moore's incredibly generous gift will have a transformative effect on Caltech," says President Thomas F. Rosenbaum, holder of the Institute's Sonja and William Davidow Presidential Chair and professor of physics. "Our ultimate goal is to provide fellowships for every graduate student at Caltech, to free these remarkable young scholars to pursue their interests wherever they may lead, independent of the vicissitudes of federal funding. The fellowships created by the Moores' gift will help make the Institute the destination of choice for the most original and creative scholars, students and faculty members alike."

Further multiplying the impact of the Moores' contribution, the Institute has established a program that will inspire others to contribute as well. The Gordon and Betty Moore Graduate Fellowship Match will provide one additional dollar for every two dollars pledged to endow Institute-wide fellowships. In this way, the Moores' $100 million commitment will increase fellowship support for Caltech by a total of $300 million.

Says Provost Edward M. Stolper, the Carl and Shirley Larson Provostial Chair and William E. Leonhard Professor of Geology: "Investigators across campus work with outstanding graduate students to advance discovery and to train the next generation of teachers and researchers. By supporting these students, the Moore Match will stimulate creativity and excellence in perpetuity all across Caltech. We are grateful to Gordon and Betty for allowing us the flexibility to devote their gift to this crucial priority."

The Moores describe Caltech as a one-of-a-kind institution in its ability to train budding scientists and engineers and conduct high-risk research with world-changing results—and they are committed to helping the Institute maintain that ability far into the future.

"We appreciate being able to support the best science," Gordon Moore says, "and that's something that supporting Caltech lets us do."

The couple's extraordinary philanthropy already has motivated other benefactors to follow their example, notes David L. Lee, chair of the Caltech Board of Trustees.

"The decision that Gordon and Betty made—to give such a remarkable gift, to make it perpetual through an endowment, and to remove any restrictions as to how it can be used—creates a tremendous ripple effect," Lee says. "Others have seen the Moores' confidence in Caltech and have made commitments of their own. We thank the Moores for their leadership."

The Moores consider their gift a high-leverage way of fostering scientific research at a place that is close to their hearts. Before he went on to cofound Intel, Gordon Moore earned a PhD in chemistry from Caltech.

"It's been a long-term association that has served me well," he says.

Joining him in Pasadena just a day after the two were married, Betty Moore became active in the campus community as well. A graduate of San Jose State College's journalism program, she secured a job at the Ford Foundation's new Pasadena headquarters and also made time to come to campus to participate in community activities, including the Chem Wives social club.

"We started out at Caltech," she recalls. "I had a feeling that it was home away from home. It gives you a down-home feeling when you're young and just taking off from family. You need that connection somehow."

After earning his PhD from Caltech in 1954, Gordon Moore took a position conducting basic research at the Applied Physics Laboratory at Johns Hopkins University. Fourteen years and two jobs later, he and his colleague Robert Noyce cofounded Intel Corp. Moore served as executive vice president of the company until 1975, when he took the helm. Under his leadership—as chief executive officer (1975 to 1987) and chairman of the board (1987 to 1997)—Intel grew from a Mountain View-based startup to a giant of Silicon Valley, worth more than $140 billion today.

Moore is widely known for "Moore's Law," his 1965 prediction that the number of transistors that can fit on a chip would double every year. Still relevant 50 years later, this principle pushed Moore and his company—and the tech industry as a whole—to produce continually more powerful and cheaper semiconductor chips.

Gordon Moore joined the Caltech Board of Trustees in 1983 and served as chair from 1993 to 2000. That same year, he and his wife established the Gordon and Betty Moore Foundation, an organization dedicated to creating positive outcomes for future generations in the San Francisco Bay Area and around the world.

Among numerous other honors, Gordon Moore is a member of the National Academy of Engineering, a fellow of the Institute of Electrical and Electronics Engineers, and a recipient of the National Medal of Technology and the Presidential Medal of Freedom. 

The Gordon and Betty Moore Graduate Fellowship Match is available for new gifts and pledges to endow graduate fellowships. For more information about the match and how to support graduate education at Caltech, please contact Jon Paparsenos, executive director of development, at (626) 395-3088 or jpapars@caltech.edu.

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Clean Water For Nepal

On the steep, tea-covered hillsides of Ilam in eastern Nepal, where 25 percent of households live below the poverty level and electricity is scarce, clean running water is scarcer still. What comes out of the region's centralized distribution systems is unfiltered, untreated, and teeming with nitrates, viruses, and E. coli. Purifying it is the consumer's responsibility.

But wood and yak dung, the only available fuels for boiling water, are precious, and purification tablets impart an unpleasant chlorine taste. The result? During the rainy season, local hospitals overflow with typhoid and gastrointestinal cases, mostly involving children and tainted runoff.

That may change, thanks to a gravity flow and slow-sand filtration system designed by Caltech undergraduates. They represent EWB-Caltech, one of the newest chapters of Engineers Without Borders USA, a nongovernmental organization (NGO) whose mission is to design and implement sustainable engineering projects in underprivileged communities.

Founded in 2012 by Sarah Wright (BS '13, bioengineering), EWB-Caltech already has about 30 members. This summer, a half dozen of the chapter's members are traveling to Ilam, where they are staying with local villagers while helping to oversee and implement the system's construction. The hillside will be partly excavated and then reconstructed. Layers of rock, gravel, sand, polyethylene sheeting, and soil will soak up rainfall, filtering and purifying it as it trickles into underground water. Pipes tapping into the underground water will run downhill to a small communal enclosure made of poured concrete, providing a reliable supply of clean water for about 100 households, with another 200 indirectly affected.

The students will not be working alone, says their mentor, environmental engineering consultant Gordon Treweek (MS '71, PhD '75) who is partnering with Caltech engineering students for the first time. "All EWB projects are community-driven, with the local workforce providing much of the labor. And we've received tremendous logistical support, including interpreters, from the Namsaling Community Development Center, an NGO in Ilam that had previously worked with an EWB chapter from the University of Colorado, Boulder."

According to EWB requirements the Nepalese must contribute 5 percent of the project's budget. EWB-Caltech copresidents Jihoon Lee (a senior in bioengineering) and Nauman Javed (a senior in physics) acknowledge that successfully coming up with the remainder—over $20,000—involved nearly continuous fund-raising. "We've been applying for grants, soliciting private donations, partnering with companies, especially water-related and environmental corporations, and we held a benefit dinner in January that was largely attended by Caltech faculty and friends," says Lee.

Both a 10-day on-site assessment trip last summer and this summer's trip were covered by individual donations and grants. The assessment trip took Treweek, Javed, and fellow Caltech senior Webster Guan (chemical engineering) to Ilam to meet with the NGO; to survey the local community of about 100 families to ascertain their needs and willingness to assist in the construction and ongoing maintenance of the water tap stand; and to gather predesign data for planning construction and estimating costs.

"The support we have received from Caltech alumni directly and through their networks of contacts at Northrop Grumman and Boeing has been invaluable in helping to keep this project moving forward," Treweek says.

After the assessment trip, the students spent the 2014–15 school year preparing detailed engineering documents using computer-aided design techniques. In this, they were assisted by the water-resource engineering firms Carollo Engineers and Montgomery Watson Harza, whose pro bono involvement did not surprise Treweek. "Consulting engineering firms frequently donate resources for projects like this," he says. "It's socially responsible, and it gives them a chance to observe future engineers addressing the four traditional phases of engineering: planning, design, fund-raising, and construction."

With preventable infectious diseases a leading component of Ilam's one-in-three infant mortality rate, the project includes a public-education component. "Besides training the local villagers who will maintain our spring-water source protection system," says Javed, "we plan to visit local schools, demonstrate how the system works, teach a little germ theory."

But no amount of careful planning can guarantee success. Similar projects have failed due to engineering problems, misaligned long-term governance strategies, eleventh-hour reprioritizations by the community, even simple miscommunication. "We've drafted plenty of contingency plans," affirms Lee, "with great support from EWB-USA. Their stringent review procedures covered every engineering and social aspect of the project, and they've given us detailed feedback on our drawings, schedules, and rationales."

After the implementation phase—which ends just one week before classes resume back in Pasadena—EWB-Caltech will continue to monitor the site for five to six years. By then the current members will have moved on and a new group of student leaders will have taken over this project. But for now, they are spending their summer trying to build a better world, drop by drop.

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New VP for Student Affairs Named

Joseph Shepherd (PhD '81), the C. L. "Kelly" Johnson Professor of Aeronautics and professor of mechanical engineering, is leaving his post as dean of graduate studies to succeed Anneila Sargent (MS '67, PhD '78), the Ira S. Bowen Professor of Astronomy, as vice president for student affairs. Shepherd's new role is effective September 15.

Sargent, who served the campus as the leader of student affairs the last eight years, announced in March that she was leaving the post to return to research and teaching full time. Shepherd, who joined the Caltech faculty in 1993, has served the last six years as the dean of graduate studies.

We recently sat down with Shepherd to talk about his past role and his new one, his strengths and goals, and his experience at Caltech.

 

Q: What does the vice president for student affairs do?

A: Student Affairs includes the offices of the undergraduate and graduate deans as well as obvious things like the registrar, undergraduate admissions, fellowships and study abroad, the career center, the health center, and the counseling center. It also includes things you might not think of—athletics; performing and visual arts, which includes the music programs, the theater program, the various arts programs, and all of the faculty and instructors that make these programs possible; and a whole group of organizations lumped under "auxiliaries."

The term "auxiliaries" is misleading, because they're central to student life. Housing and dining are the biggest parts, but there are services like the C-Store, the Red Door Café, the Caltech Store and Wired.

 

Q: What makes this role exciting for you?

A:  People speculate about what it is that makes Caltech a great school. A lot of folks say, "Well, it's because it's so small." But I think it's also because we work with people instead of creating some bureaucratic mechanism to solve problems. We say, "All right, what's the issue here? How can we resolve this?" instead of, "We need to create a rule. And then we need to create a group to enforce the rule." My approach is to ask, "What do we want the outcome to be?" In Student Affairs, you want the outcome to be something that supports the students, supports the faculty, and then you make sure that it's not going to adversely affect the Institute.

 

Q: Are there any changes coming, any initiatives you want to establish?

A: We need to think about how we build on the strengths we have and improve the things that we're weakest at. Before you make any changes to an organization, you need to understand those two things. There are a lot of parts to Student Affairs, so I need to understand the strong points of those organizations, and then get them to help me formulate what's important to do.

You always have to be careful of unintended consequences. As they say in chess, you want to think several moves deep. All right, suppose we do that. What will it mean for different parts of our population? Do we make this choice based on the data we have, or do we need more data? Will there be effects on people we haven't thought about? Maybe we need to go talk to those people.

When you have the authority to change things, you also have the responsibility to ask, "Are these the right changes?" Nothing happens in isolation. Anything you do is invariably going to wind up touching quite a few people.

 

Q: You've been dean of graduate studies since 2009. Did you consider taking a breather before jumping into this?

A: Well, much to my surprise, I found that being the dean of graduate studies was rewarding in many different ways. Sometimes you had to do some difficult things, but I actually liked being the dean. I was able, to some extent, to continue my research. I did some teaching—although last year I taught a major course all three terms, and I had my research group—and I was the dean of graduate studies. That taught me a lesson: a man's got to know his limitations.

So when I was asked if I would take this position, I did think about taking a break and not doing it. I enjoy my research and I enjoy teaching. I enjoy working with students, but I also enjoy trying to help the Institute as a whole. Here at Caltech, we pride ourselves on the notion that we have this very special environment. We have this small school, and we have dedicated professionals that work together with faculty to nurture that environment—having faculty who are invested in participating in the key administrative roles is essential.

When I was a graduate student here, my adviser was Brad Sturtevant [MS '56, PhD '60, and a lifelong faculty member thereafter]. Brad was the executive officer for aeronautics [1972-76]. He was in charge of the committee that built the Sherman Fairchild Library and he was on the faculty board. He emphasized to me that being involved in administration was just as valuable as all the other aspects of being a faculty member. He was a dedicated researcher, but he also felt strongly that you should be a good citizen. You should contribute.

 

Q: It seems like this is more than just a duty to you, though.

A: I'm looking forward to it. I'm also very conscious of the responsibility. I think it's going to be important for us all to think about how we maintain the excellence of the Institute and that we imagine how this place is going to evolve. As society evolves around us, we will naturally wind up changing. We need to do that in a thoughtful way so that we continue to be the special organization that we are.

At the end of the day, I'm counting on help from the faculty and staff. Caltech works because of the committed individuals within our organizations, the personal connections we form as we work together and the cooperation across the campus that these connections enable.  It's a collective enterprise.

I think administration is not something that's done to people. It's being responsible for making sure that folks have the right work environment, the right job assignments, and the right resources. It's making sure we're doing the right things with the finite resources we have. One of our former presidents said something that's always stuck with me: an administrator's goals are not about their own career so much as helping the careers of others. You need to think about how you're helping the people working for you, because they have goals and aspirations. That's where you take your satisfaction.

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Thursday, September 24, 2015
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3rd Annual Caltech Teaching Conference: Schedule and RSVP Available Now

Better Memory with Faster Lasers

DVDs and Blu-ray disks contain so-called phase-change materials that morph from one atomic state to another after being struck with pulses of laser light, with data "recorded" in those two atomic states. Using ultrafast laser pulses that speed up the data recording process, Caltech researchers adopted a novel technique, ultrafast electron crystallography (UEC), to visualize directly in four dimensions the changing atomic configurations of the materials undergoing the phase changes. In doing so, they discovered a previously unknown intermediate atomic state—one that may represent an unavoidable limit to data recording speeds.

By shedding light on the fundamental physical processes involved in data storage, the work may lead to better, faster computer memory systems with larger storage capacity. The research, done in the laboratory of Ahmed Zewail, Linus Pauling Professor of Chemistry and professor of physics, will be published in the July 28 print issue of the journal ACS Nano.

When the laser light interacts with a phase-change material, its atomic structure changes from an ordered crystalline arrangement to a more disordered, or amorphous, configuration. These two states represent 0s and 1s of digital data.

"Today, nanosecond lasers—lasers that pulse light at one-billionth of a second—are used to record information on DVDs and Blu-ray disks, by driving the material from one state to another," explains Giovanni Vanacore, a postdoctoral scholar and an author on the study. The speed with which data can be recorded is determined both by the speed of the laser—that is, by the duration of each "pulse" of light—and by how fast the material itself can shift from one state to the other.

Thus, with a nanosecond laser, "the fastest you can record information is one information unit, one 0 or 1, every nanosecond," says Jianbo Hu, a postdoctoral scholar and the first author of the paper. "To go even faster, people have started to use femtosecond lasers, which can potentially record one unit every one millionth of a billionth of a second. We wanted to know what actually happens to the material at this speed and if there is a limit to how fast you can go from one structural phase to another."

To study this, the researchers used their technique, ultrafast electron crystallography. The technique, a new development—different from Zewail's Nobel Prize–winning work in femtochemistry, the visual study of chemical processes occurring at femtosecond scales—allowed researchers to observe directly the transitioning atomic configuration of a prototypical phase-change material, germanium telluride (GeTe), when it is hit by a femtosecond laser pulse.

In UEC, a sample of crystalline GeTe is bombarded with a femtosecond laser pulse, followed by a pulse of electrons. The laser pulse causes the atomic structure to change from the crystalline to other structures, and then ultimately to the amorphous state. Then, when the electron pulse hits the sample, its electrons scatter in a pattern that provides a picture of the sample's atomic configuration as a function of the time.

With this technique, the researchers could see directly, for the first time, the structural shift in GeTe caused by the laser pulses. However, they also saw something more: a previously unknown intermediate phase that appears during the transition from the crystalline to the amorphous configuration. Because moving through the intermediate phase takes additional time, the researchers believe that it represents a physical limit to how quickly the overall transition can occur—and to how fast data can be recorded, regardless of the laser speeds used.

"Even if there is a laser faster than a femtosecond laser, there will be a limit as to how fast this transition can occur and information can be recorded, just because of the physics of these phase-change materials," Vanacore says. "It's something that cannot be solved technologically—it's fundamental."

Despite revealing such limits, the research could one day aid the development of better data storage for computers, the researchers say. Right now, computers generally store information in several ways, among them the well-known random-access memory (RAM) and read-only memory (ROM). RAM, which is used to run the programs on your computer, can record and rewrite information very quickly via an electrical current. However, the information is lost whenever the computer is powered down. ROM storage, including CDs and DVDs, uses phase-change materials and lasers to store information. Although ROM records and reads data more slowly, the information can be stored for decades.

Finding ways to speed up the recording process of phase-change materials and understanding the limits to this speed could lead to a new type of memory that harnesses the best of both worlds.

The researchers say that their next step will be to use UEC to study the transition of the amorphous atomic structure of GeTe back into the crystalline phase—comparable to the phenomenon that occurs when you erase and then rewrite a DVD.

Although these applications could mean exciting changes for future computer technologies, this work is also very important from a fundamental point of view, Zewail says.

"Understanding the fundamental behavior of materials transformation is what we are after, and these new techniques developed at Caltech have made it possible to visualize such behavior in both space and time," Zewail says.

The work is published in a paper titled "Transient Structures and Possible Limits of Data Recording in Phase-Change Materials." In addition to Hu, Vanacore, and Zewail, Xiangshui Miao and Zhe Yang are also coauthors on the paper. The work was supported by the National Science Foundation and the Air Force Office of Scientific Research and was carried out in Caltech's Center for Physical Biology, which is funded by the Gordon and Betty Moore Foundation.

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New Dean of Graduate Studies Named

On July 1, 2015, Doug Rees, the Roscoe Gilkey Dickinson Professor of Chemistry, will begin serving as the new dean of graduate studies at Caltech.

"Doug's experience and concern with graduate education make him an ideal choice for dean of graduate studies. I am very pleased that he is willing to make this commitment to the Institute and its students," says Anneila Sargent, vice president for student affairs and the Ira S. Bowen Professor of Astronomy.

As the new dean, Rees will be the principal administrator and representative of Caltech's graduate education program, responsible for attending to concerns regarding the welfare of graduate students as well as for upholding the Institute's rules and policies.

"There are many groups essential to the effective operation of our graduate program that I want to get to know better, starting with the graduate students, the Graduate Office staff, and the option administrators and option reps," says Rees. "In my 26 years at Caltech, I've gained an appreciation for how the graduate programs in biochemistry and molecular biophysics and in chemistry operate, but the cultures in different options across campus can vary significantly, and I look forward to better understanding these distinctions."

Rees says that he is also very much looking forward to working directly with graduate students, staff, and faculty on behalf of the graduate program. Of particular interest during his tenure will be issues relating to the well-being and professional development of graduate students.

"I find research to be an adventure that, while exhilarating, is also challenging, frustrating, and even stressful; those aspects, however, are not incompatible with having a positive student experience and a supportive environment," Rees says. He adds that his priorities will be to raise fellowship support, increase the diversity of the graduate student body, and ensure that students have access to appropriate support services such as health care, counseling, and day care. "In addition, I also hope to be able to explore mechanisms to better prepare students for life after Caltech, including both academic and nonacademic career options," he says.

In his new post, Rees will take the place of C. L. "Kelly" Johnson Professor of Aeronautics and Mechanical Engineering Joseph Shepherd, who has served as the dean of graduate studies since 2009. "Joe leaves big shoes to fill and the campus owes him a huge debt of gratitude for all he has accomplished as dean of graduate studies. What I have learned from watching him in action over the past six years, and more recently as he has been helping me during this transition period, is that the most important quality for the dean is to care about the students—and I will definitely be working to follow his example," Rees says.

Rees received his undergraduate degree from Yale University in 1974 and his PhD from Harvard in 1980, becoming a professor at Caltech in 1989. An investigator with the Howard Hughes Medical Institute, Rees also served as the executive officer for chemistry from 2002 to 2006 and the executive officer for biochemistry and molecular biophysics from 2007 to 2015.

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