Friday, May 30, 2014
Annenberg 105

Caltech Teaching Assistant Training for 2014-2015 Year

From Nature to the Pharmacy: The Chemistry Behind Modern Medicines

Watson Lecture Preview

Natural products—molecules originally isolated from bacteria, fungi, plants, and other sources—often have medicinal values that can be enhanced by careful reengineering. For example, an aspirin tablet is a much better pain reducer than an extract of willow bark. Chemistry professor Sarah Reisman's lab develops synthetic methods to help organic chemists tweak existing molecules and even build new ones from scratch. On Wednesday, May 7, she will describe some tools of the trade.

The talk begins at 8:00 p.m. in Caltech's Beckman Auditorium. Admission is free.

 

Q: What do you do?

A: I'm a synthetic organic chemist. I spend a lot of time thinking about how to make small, carbon-based molecules—roughly the size of steroids, and comparable to most pharmaceuticals—that have some sort of biological activity. We try to prepare them in our laboratory so that through collaborations we can figure out how they work. We're more on the basic-research side of the spectrum; we develop synthetic tools that we, or researchers in pharma, can use to build molecules.

Natural products are relatively rare compounds. For example, the important antitumor drug Taxol—which we do not work on—was originally isolated from the Pacific yew tree. The yew population would have been decimated if the tree had been used as the commercial source of paclitaxel, which is the generic name for the drug. The manufacturers figured out how to culture an intermediate compound and finish the preparation synthetically, but first the demand for material inspired several chemical syntheses of the natural product.

Total chemical syntheses of natural products are complicated endeavors, because these molecules have very specific three-dimensional structures. The reactive parts that give the molecule its function all have to be connected in the correct spatial orientation, so how you bring the atoms together is really important. You have to figure out how to selectively engage and modify one part of the molecule without messing up the rest of it. Organic chemists have spent a long time developing these types of selective reactions, which is really what we do in my lab. And despite constant advancement in our understanding of synthetic organic chemistry, it is very much an empirical science. There are all sorts of rules and guidelines, but there are frequently exceptions to the rules and that's where things get interesting.

Working out the best order to do things is a big part of the challenge. We want to make these molecules in a reasonable way—usually in 20 synthetic steps or less. That's still on the high side, but it's reasonable. It's rare to obtain a 100 percent yield, and 20 synthetic steps with even a 75 percent yield at each step would lead to a very low overall yield. So we look for high-yield transformations wherever possible.

 

Q: What's exciting about this? What motivates you?

A: Well, I think it's pretty neat that most of what we make has never been made before. The goal is to make some compound that nature produces, but we get to design new molecules along the way.

We usually start with the target molecule and work backward—using either known transformations, or our intuition about reactions we might be able to develop—and as we simplify the target, we get to compounds that haven't been made before. Then we ask ourselves, okay, how do we actually make those compounds? And we work our way forward to those checkpoints—again, using known reactions, or new ones that we develop—but now starting from commercially available chemical building blocks.

I was drawn to organic chemistry because there's a tremendous amount of creativity embedded within it. There is no definitive right way to make a molecule. It's like putting together a jigsaw puzzle where you get to cut your own pieces. You figure out how to break the molecule up, and then how best to reassemble it. It's a lot of fun.

 

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

A: When I went to college I wanted to go to medical school. My declared major was biology, because I had heard that that was a good way to get in. Then, as a sophomore, I had to take organic chemistry as part of the premed requirement. I got hooked. It was unlike any other chemistry course I'd ever taken, because it was so creative. After I got into an organic chemistry lab and did some research, there was no looking back.

 

 

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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Douglas Smith
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The Chemistry Behind Modern Medicines
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Fu, Harrison, and Preskill Elected to the National Academy of Sciences

Three professors at Caltech have been elected to the prestigious National Academy of Sciences. The announcement was made Tuesday, April 29, in Washington D.C.

The new Caltech electees are Gregory C. Fu, Altair Professor of Chemistry; Fiona A. Harrison, Benjamin M. Rosen Professor of Physics; and John P. Preskill, Richard P. Feynman Professor of Theoretical Physics.

Fu is a synthetic organic chemist focusing on transition-metal catalysis and nucleophilic catalysis. He is currently developing enantioselective reactions and exploring the use of copper and nickel catalysts. In 2012, Fu won the Award for Creative Work in Synthetic Organic Chemistry from the American Chemical Society. He is a fellow of both the American Academy of Arts and Sciences (2007) and the Royal Society of Chemistry (2005).

Harrison specializes in observational and experimental high-energy astrophysics. She is the principal investigator for NASA's NuSTAR Explorer Mission. Harrison is recognized for her leadership in the design, development and launch of NuSTAR, as well as leading the team in the mission's scientific return.  As a result of almost two decades of technology development, NuSTAR is revolutionizing our view of the high-energy X-ray sky. Harrison was elected to the American Academy of Arts and Sciences in 2014, was elected as a fellow of the American Physical Society in 2012, and won a NASA Outstanding Public Leadership Medal in 2013.

Preskill is a theoretical physicist who began his career in particle physics (in particular, the interface between particle physics and cosmology) before moving to a specialization in quantum information and quantum computing. In 2000, Preskill founded the Institute for Quantum Information with the aim of harnessing principles of quantum mechanics to aid in particularly challenging information-processing tasks. He is a fellow of the American Physical Society.

The National Academy of Sciences is a private organization of scientists and engineers dedicated to the furtherance of science and its use for the general welfare. It was established in 1863 by a congressional act of incorporation signed by Abraham Lincoln that calls on the academy to act as an official adviser to the federal government, upon request, in any matter of science or technology.

The election of Fu, Harrison, and Preskill brings the total Caltech membership to 75 faculty and three trustees.

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Cynthia Eller
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Caltech Faculty Elected to the American Academy of Arts and Sciences

The American Academy of Arts and Sciences has elected three Caltech faculty members as academy fellows. They are John F. Brady, Chevron Professor of Chemical Engineering and Mechanical Engineering and executive officer for chemical engineering; Kenneth A. Farley, W. M. Keck Foundation Professor of Geochemistry and chair of the Division of Geological and Planetary Sciences; and Fiona A. Harrison, Benjamin M. Rosen Professor of Physics.

"It is a privilege to honor these men and women for their extraordinary individual accomplishments," said Don Randel, chair of the academy's board of directors, of the 204 newly elected fellows and 16 foreign honorary members. "The knowledge and expertise of our members gives the academy a unique capacity—and responsibility—to provide practical policy solutions to the pressing challenges of the day. We look forward to engaging our new members in this work."

Brady works in the area of complex fluids and active matter that includes microstructural elements such as suspensions, colloidal dispersions, and self-propelling particles. Understanding these materials led Brady to develop a novel computational method called Stokesian dynamics. He won the 2012 Fluid Dynamics Prize from the American Physical Society and was elected to the National Academy of Engineering in 1999.

Most of Farley's research has focused on terrestrial geochemistry, but he is now increasingly interested in planetary science and especially exploration of the geochemistry, geology, and geomorphology of Mars. In his laboratory on the Caltech campus, Farley and his group measure noble gases such as helium and neon in rock and mineral samples. One major objective of this work is determining the ages and surface exposure history of Earth's geological features. Farley was recently involved in the first-ever experiments of this type carried out on the surface of Mars, via an instrument on board the Mars Science Laboratory's Curiosity rover. He has received the Day Medal of the Geological Society of America and the Macelwane Award of the American Geophysical Union, and was elected to the National Academy of Sciences in 2013.

Harrison specializes in observational and experimental high-energy astrophysics. She is the principal investigator for NASA's NuSTAR Explorer Mission and uses this satellite, along with other satellites and ground-based telescopes, to understand black holes, neutron stars, and supernova remnants. In her labs at Caltech, Harrison's group develops high-energy X-ray detectors and instrumentation for future space missions. She was elected to the American Physical Society in 2012 and won a NASA Outstanding Public Leadership Medal in 2013.

Also named to the academy this year is Katherine T. Faber, the Walter P. Murphy Professor of Materials Science and Engineering at Northwestern University, who will be joining the Caltech faculty on July 1 as the Simon Ramo Professor of Materials Science. Faber's research focuses on understanding fracture and toughening of brittle materials such as those used for high-temperature coatings for power generation applications. She also works on the fabrication of ceramic materials with controlled porosity. She is cofounder and codirector of the Northwestern University-Art Institute of Chicago Center for Scientific Studies in the Arts (NU-ACCESS), which employs advanced materials science techniques for conservation science. Faber is a Distinguished Life Member of the American Ceramic Society (2013), and became a National Science Foundation American Competitiveness and Innovation Fellow in 2010.

The total number of Caltech faculty named to the academy is now 97.

The academy was founded in 1780 by John Adams, James Bowdoin, John Hancock, and other scholar-patriots "to cultivate every art and science which may tend to advance the interest, honor, dignity, and happiness of a free, independent, and virtuous people." The academy has elected as fellows and foreign honorary members the finest minds and most influential leaders from each generation, including George Washington and Ben Franklin in the 18th century, Daniel Webster and Ralph Waldo Emerson in the 19th, and Albert Einstein and Winston Churchill in the 20th. The current membership includes more than 250 Nobel laureates and 60 Pulitzer Prize winners.

A full list of new members is available on the academy website at https://www.amacad.org/content/members/members.aspx.

The academy will welcome this year's new fellows and foreign honorary members at its annual induction ceremony at the academy's headquarters in Cambridge, Massachusetts, on October 11, 2014.

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Cynthia Eller
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On the Front Lines of Sustainability

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On the Front Lines of Sustainability
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The chemical processes used to make products ranging from pharmaceuticals to perfumes can have a harmful impact on the environment. However, Caltech chemist and Nobel laureate Robert Grubbs has spent several decades developing catalysts—compounds that speed up a chemical reaction—that can make the synthesis of these products more efficient and ecologically friendly, ultimately reducing their environmental footprint. Similarly, chemist Brian Stoltz is developing new strategies for the synthesis of compounds needed in the chemical, polymer, and pharmaceutical industries. His new processes rely upon oxygen and organometallic catalysts—greener alternatives to the toxic metals that are normally used to drive such reactions.

Switching from paper files to cloud-based data storage might seem like an obvious choice for sustainability, but can we further reduce the environmental impact of storing data? The theoretical work of engineer and computer scientist Adam Wierman suggests that with the right algorithms, we can. Today, data centers—the physical storage facilities Wierman calls the "SUVs of the Internet"—account for more than 1.5 percent of U.S. electricity usage. And as more data goes online, that number is expected to grow. Wierman's work helps engineers design algorithms that will reroute data, with preference to centers that use renewable energy sources like wind and solar.

Energy from the sun—although free and abundant—cannot easily be stored for use on dreary days or transported to cloudy regions. Caltech engineer and materials scientist Sossina Haile hopes to remove that barrier with a specific type of solar reactor she has developed. The reactor is lined with ceramic cerium oxide; when this lining is heated with concentrated sunlight it releases oxygen, priming it to remove oxygen from water molecules or carbon dioxide on cooling, thus creating hydrogen fuel or "syngas"—a precursor to liquid hydrocarbon fuels. This conversion of the sun's light into storable fuel could allow solar-derived power to be available day and night.

Caltech student participants in the Department of Energy's biennial Solar Decathlon competition set out to prove that keeping a house lit up, cooled down, and comfortable for living is possible—even while off the grid. The Techers teamed up with students at the Southern California Institute of Architecture to create CHIP and DALE, their entries in the 2011 and 2013 competitions, respectively. These functional and stylish homes, powered solely by the sun, were engineered with innovative components including a rainwater collection system and moving room modules that optimize heating and cooling efficiency. 

Although many of us take the nearest bathroom for granted, working toilets require resources and infrastructure that may not be available in many parts of the world. Inspired by the "Reinventing the Toilet Challenge" issued by the Bill and Melinda Gates Foundation, environmental scientist and engineer Michael Hoffmann and his team applied his research in hydrogen evolution and water treatment to reengineer the toilet. The Caltech team's design—which won the challenge in 2012—can serve hundreds of people each day, treat its own wastewater, and generate electricity, providing a sustainable and low-cost solution to sanitation and hygiene challenges in the developing world. Prototypes are being tested in India and China for use in urban and remote environments in the developing world.  

Geophysicist Mark Simons studies the mechanics of the Earth—furthering our understanding of what causes our planet to deform over time. His research often involves using satellite data to observe the movement associated with seismic and volcanic activity, but Simons is also interested in changes going on in the icy parts of Earth's surface, especially the dynamics of glaciers. By flying high above Iceland's ice caps, Simons and his colleagues can track the glaciers' melt-and-freeze response in relation to seasonal and long-term variations in temperature—and their potential response to climate change.

The production of industrial nitrogen fertilizer results in 130 million tons of ammonia annually—while also requiring high heat, high pressure, and lots of energy. However, in a process called nitrogen fixation, soil microorganisms that live near the roots of certain plants can produce a similar amount of ammonia each year. The bugs use catalysts called nitrogenases to convert nitrogen from the air into ammonia at room temperature and atmospheric pressure. By mimicking the behavior of these microorganisms, Jonas Peters and his colleagues synthesized an iron-based catalyst that allows for nitrogen fixation under much milder conditions. The catalyst could one day lead to more environmentally friendly methods of ammonia production.

Traditionally, the photovoltaic cells in solar panels have been expensive and have had limited efficiency—making them a hard sell in the consumer market. Engineer and applied physicist Harry Atwater's work suggests that there is a thinner and more efficient alternative. Atwater, who is also the director of the Resnick Sustainability Institute, uses thin layers of semiconductors to create photovoltaics that absorb sunlight as efficiently as thick solar cells but can be produced with higher efficiency than conventional cells.

The generation of chemical fuels from sunlight could completely change the way we power the planet. Researchers in the laboratory of Caltech chemist Nate Lewis are working to develop different components of a fuel-producing device that could do just that called a photoelectrochemical cell. The cell would consist of an upper layer that could absorb sunlight, carbon dioxide, and water vapor, a middle layer consisting of light absorbers and catalysts that can produce fuels, which are then released through the device's bottom layer. When such a device is created, the Joint Center for Artificial Photosynthesis, of which Lewis is the scientific director, aims to ease the transfer of these technologies to the private sector. 

Clean energy from the wind is a promising alternative to fossil fuels, but giant pinwheel-like wind turbines that are common on many wind farms can create dangerous obstacles for birds as well as being an unpleasant addition to a landscape's aesthetic. To combat this problem, Caltech engineer and fluid-mechanics expert John Dabiri is testing a new design for wind turbines, which looks a bit like a spinning eggbeater emerging from the ground. By placing these columnar vertical wind turbines in a careful arrangement—an arrangement inspired by the vortex of water created behind a swimming fish—his smaller vertical turbines create just as much energy as the "pinwheels" and on a much smaller land footprint.

In the early 1990s, Caltech bioengineer Frances Arnold pioneered "directed evolution"—a new method of engineering custom-built enzymes, or activity-boosting proteins. The technique allows mutations to develop in the enzyme's genetic code; these mutations can give the enzyme properties that don't occur in nature but are beneficial for human applications. The selectively enhanced enzymes help microbes turn plant waste and fast-growing grasses into fuels like isobutanol, which could sustainably replace more than half of U.S. oil imports, Arnold says. She's also exploring ways the technique could help factories to make pharmaceuticals and other products in much cleaner and safer ways.

The combined research efforts of Richard Flagan, John Seinfeld, Mitchio Okumura, and Paul Wennberg aim to improve our understanding of various aspects of climate change. Chemical engineer Flagan is pioneering ways to measure the number and sizes of particles in the air down to that of large molecules. Seinfeld studies where particles in the air come from, how they are produced by airborne chemical reactions, and the effect they have on the world's climate. Chemical physicist Okumura studies the chemical reactions that occur when sunlight encounters air pollution and results in smog. Wennberg, an atmospheric chemist, studies the natural and human processes that affect smog formation, the health of the ozone layer, as well as the lifetime of greenhouse gases. Wennberg and his colleagues join a legacy of Caltech researchers who have improved air quality through key discoveries about pollution.

In the past, researchers have discovered materials that can act as reaction catalysts, driving sunlight to split water into hydrogen fuel and an oxygen byproduct. However, these wonder materials are often expensive and in short supply. The research of chemist Harry Gray, who leads the National Science Foundation-funded Center for Chemical Innovation in Solar Fuels program, tests combinations of Earth-abundant metals to search for an inexpensive catalyst that boosts the water-splitting reaction with the sun. Gray also coleads an outreach project in which students in the classroom can participate in the race for solar fuels by testing thousands of materials and reporting their results to Caltech researchers.

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Although Earth Week has officially come to a close, Caltech's commitment to sustainability continues. In this feature, you will meet some of the researchers at Caltech whose work is contributing to a greener planet and to the long-term improvement of our global environment.

Research for a Greener Future

Today's Earth Week feature highlights three cross-disciplinary research centers where Caltech scientists and engineers collaborate on projects that will have a positive impact on energy, the environment, and Earth's sustainable future.

The Ronald and Maxine Linde Center for Global Environmental Science

The Ronald and Maxine Linde Center for Global Environmental Science brings together researchers from chemistry, engineering, geology, environmental science, and other disciplines, with the goal of understanding the global environment and developing solutions to complex environmental problems. Linde Center scientists investigate how Earth's climate and its atmosphere, oceans, and biosphere have varied in the past and how they may change in the future. They are working on solutions to vexing challenges in climate change prognosis and mitigation, and to improve air and water quality.

The Linde Center was established thanks to support from Caltech alumnus and trustee Ronald Linde and his wife, Maxine. Led by acting director Paul Wennberg, Caltech's R. Stanton Avery Professor of Atmospheric Chemistry and Environmental Science and Engineering, the center is housed in the Linde + Robinson Laboratory, which was constructed in 1932 as an astronomy lab. The building recently underwent extensive renovations, to become one of the nation's most energy-efficient laboratories and the first existing historic building to earn the LEED Platinum rating. In 2012, Linde + Robinson was honored with a 2012 Los Angeles Conservancy Preservation Award for the "exceptionally creative and sensitive approach" of the renovation. The project, the conservancy noted, "not only preserved the building's unique historic features, it found brilliant new uses for them—particularly the solar telescope, built as the centerpiece of the original building but functionally obsolete. Now it tracks the sun and uses the light it captures for both illumination and exploration."

Resnick Sustainability Institute

Caltech's Resnick Sustainability Institute was created to fund and foster innovative Caltech-based sustainability and energy-science research collaborations with the potential to develop renewable-energy technologies that may one day help solve our global energy and climate challenges. The mission of the institute, which was founded with a generous gift from Stewart and Lynda Resnick, spans research, education, and communications. Current projects include research into energy generation, such as advanced photovoltaics, photoelectrochemical solar fuels, cellulosic biofuels, and wind-energy system design; energy conversion work on batteries and fuel cells; and research into technologies for energy efficiency and management, such as fuel-efficient vehicles, green chemical synthesis, and thermoelectric materials, as well as advanced research on electrical grid control and distribution.

This year the Resnick Sustainability Institute debuted two new initiatives: the Resonate Awards, which honor breakthrough achievements in energy science and sustainability, and a prize postdoctoral fellowship program. The Resonate Award winners will be announced at the Fortune Brainstorm GREEN conference in May 2014, and the inaugural class of postdoctoral fellows will be announced this fall.

Led by Harry Atwater, Caltech's Howard Hughes Professor and professor of applied physics and materials science, the institute is collocated with the Joint Center for Artificial Photosynthesis (JCAP) in the recently renovated Jorgensen Laboratory, which has been awarded LEED Platinum certification. In the renovation, Caltech and its partners were able to reuse or recycle over 90 percent of the materials removed from the original facility, a computer science building. Jorgensen has high-efficiency lighting and HVAC systems, a "living roof" composed of evergreen and drought-tolerant grasses, and water-saving plumbing and landscaping, among other green features.

The Joint Center for Artificial Photosynthesis (JCAP)

JCAP, established in 2010 as a U.S. Department of Energy (DOE) Energy Innovation Hub, is the nation's largest research effort focused on artificial photosynthesis. Led by researchers from Caltech (JCAP South, housed at the Jorgensen Laboratory) and partner Lawrence Berkeley National Laboratory (JCAP North), the center aims to create a low-cost artificial generator that uses sunlight, carbon dioxide, and water to make fuel from the sun 10 times more efficiently than current living crops. Once a prototype generator is developed, it will be handed off to private-sector companies to launch a new solar-fuels industry. Such a transformative breakthrough would reduce our country's dependence on oil and enhance energy security.

JCAP researchers include Scientific Director Nathan S. Lewis, Caltech's George L. Argyros Professor and professor of chemistry; Jonas Peters, the Bren Professor of Chemistry; William A. Goddard, Charles and Mary Ferkel Professor of Chemistry, Materials Science, and Applied Physics; and Harry Atwater.

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Caltech and JPL Experts Discuss Climate Change

In today's installment of our Earth Week 2014 features, Caltech experts share their knowledge about climate change.

 

Caltech professor Jess Adkins, a geochemist and paleoclimatologist, offers insight into global warming in the video "Is There Hope for Planet Earth?" produced by Green Wish, a nonprofit organization that funds green initiatives at the local level. In the video, Adkins talks about the history of climate change, where we are today, and what we can do to mitigate its impact in the future.

 

On April 22—Earth Day—the Caltech Center for Teaching, Learning, & Outreach sponsored an "Ask A Scientist" panel on the Caltech campus to answer questions about climate change and earth sciences. Panel members included David Crisp, JPL senior research scientist and principal investigator of the NASA Earth System Science Pathfinder Orbiting Carbon Observatory mission; Joshua Fisher, JPL research scientist, Water and Carbon Cycles Group; science communicator and education specialist Laura Tenenbaum; and Caltech alumnus Julius Su (BS '98 and '99, PhD '07), cofounder of Su-Kam Intelligent Education Systems (SKIES). Su used the SKIES iPad app, an online learning and information crowdsourcing tool, to relay online and audience questions to the panelists. The video is a recording of the live event.

 

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