Frances Arnold Wins Eni Award for Renewable-Energy Work

PASADENA, Calif.—For the second year in a row, a faculty member from the California Institute of Technology (Caltech) has been awarded the Eni Award in Renewable and Non-Conventional Energy. This year, chemical engineer Frances Arnold—who pioneered methods of "directed evolution" for the production and optimization of biological catalysts—has been chosen to receive the distinction, along with her colleague James Liao of UCLA.

Arnold, Caltech's Dick and Barbara Dickinson Professor of Chemical Engineering, Bioengineering and Biochemistry, has shown that mimicking Darwinian evolution in the laboratory is an efficient way to engineer the amino-acid sequence of a protein, endowing it with new capabilities or improving its performance. Arnold and her colleagues have used directed evolution to improve catalysts for making fuels and chemicals from renewable resources.

"There are a lot of creative people working on renewable and non-conventional energy, so it is a huge honor to be selected for this distinction," Arnold says. "This prize recognizes the basic technology we've developed over the years, but especially the application of directed evolution to making things that we currently get from non-renewable hydrocarbons."

The Eni Awards are international prizes that recognize outstanding research and development in the fields of energy and the environment. Eni is an integrated energy company based in Italy. According to the company's website, "The Eni Award was created to develop better use of renewable energy, promote environmental research and encourage new generations of researchers."

A 24-person scientific award committee selects the honorees each year in four categories: New Frontiers of Hydrocarbons, Renewable and Non-Conventional Energy, Protection of the Environment, and Debut in Research. Three additional prizes are awarded for innovative and applied research within Eni, in energy and the environment.

In 2012, Harry A. Atwater, Caltech's Howard Hughes Professor and professor of applied physics and materials science, and director of the Resnick Sustainability Institute, along with his colleague Albert Polman of the Dutch Research Institute AMOLF, was awarded the same Eni Award in Renewable and Non-Conventional Energy, for developing new ultrathin, high-efficiency solar cells.

Of Caltech's back-to-back Eni Awards, Arnold says, "It shows that the renewable-energy research going on at Caltech is world-class. Other places may have much bigger programs, but for impact and accomplishment, the research that the Resnick Institute supports is recognized throughout the world as being at the very top. These groups are making real progress on some of the most important problems we face today."

Arnold, Liao, and the other 2013 awardees will receive their prizes on June 27 at the Presidential Palace in Rome.

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Decision Making and Quality Control in Early Moments of a Protein’s Life

Watson Lecture Preview

Professor of Chemistry Shu-ou Shan studies the gears and springs in the molecular machinery of life. She'll be giving us a guided tour of the cellular assembly line at 8 p.m. on Wednesday, May 22, 2013 in Caltech's Beckman Auditorium. Admission is free.

 

Q: What do you do?

A: I'm a biochemist-slash-biophysicist. I want to understand how our cells' molecular machinery works. These machines are large assemblies of proteins and other molecules that fit together in very specific ways and whose parts move in close coordination to perform the functions of life. I'm particularly interested in understanding how these machines make accurate decisions in the crowded, complex environment inside the cell. These decisions ultimately control what the cell does—will it function correctly, will it turn into a cancer cell, or will it die prematurely?

I'm looking specifically at the decisions that have to be made by various cellular machines every time a new protein molecule is synthesized. For example, there are chaperone machines that help the new protein fold into the right structure. There are protein localizer machines that take the new protein to the right part of the cell—to an organelle, to the cell membrane, or even across the cell membrane, if the protein is a hormone or some other substance the cell intends to secrete. And there are all kinds of enzymes that put chemical tags on the new protein for all sorts of reasons.

We study how these machines work by using a lot of methods developed by chemists and physicists. For example, we can make a protein in a test tube and attach fluorescent dyes to various parts of it. The light from the fluorescence tells us how the protein is interacting with other proteins and how the protein's molecular structure is changing during those interactions. This lets us identify the important interactions that enable the protein to function properly. We do this over and over, putting the dyes in different places and using the data to build a model of how we think the protein works. Then we wipe away the crucial interactions by modifying the protein and see if that disrupts the protein's function in the cell in the ways we predicted.

 

Q: How did you get started on this line of work?

A: I've always believed that when true understanding comes, complexity reduces to simplicity. So the question for me when I was going through middle school and high school was, "What can I do to contribute to that enterprise?"

Then, in high school, I had a revelation. My biology class was studying Mendelian genetics, which are patterns of heredity that you can explain by recombining genes in different ways. Meanwhile, my organic chemistry class was learning about proteins and nucleic acids, and how a few simple principles of base pairing in a molecule of DNA led to a model for how our genetic information is replicated. And I made the connection that all the phenomena of heredity came down to chemical structures I could draw on a piece of paper. They happened because of changing chemical structures, which happened because chemical bonds were made or broken, which happened because the laws of physics drove them. That was an exciting moment.

I majored in chemistry and biochemistry at the University of Maryland, where I also took all the advanced math and physics classes available. They were not required, but I found them very interesting. I went to Stanford for my PhD, where I joined a lab that was trying to find the fundamental principles that explain how enzymes work. It was fantastic training, because we had to think very rigorously in terms of physics and chemistry while still trying to understand the connection to biological function. And at the end, I realized that I still wanted to do biology, so I went on to be a postdoc at a cell biology lab at UC San Francisco. That's where I started working on how proteins make decisions.

 

Q: What gets you really excited about it?

A: Being able to explain very complex and amazing phenomena in the cell at the level of chemical principles. We make a measurement of a molecular action in a test tube and put together a mathematical model that predicts how a certain protein is going to be treated by the cell. Then we go back and test those predictions, see if they match up—not just the trend of the line, but the actual numbers. Those are the divine moments when we really understand something.

My interest in science started with physics and chemistry. Like most physicists, I'm amazed by the beauty and elegance with which the laws of physics explain, and even predict, the phenomena we see around us. I still hold the optimistic belief that ultimately we will explain the complex phenomena of life in terms of simple principles. I guess if science is likened to a craft, I am really a watchmaker. I have to take it down to the very last detail and see how it's all pieced together.

 

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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Brown, Farley, and Seinfeld Elected to National Academy of Sciences

Based on their distinguished achievements in original research, three Caltech professors—Mike Brown, Ken Farley, and John Seinfeld—are among the 84 members and 21 foreign associates newly elected to the National Academy of Sciences. The announcement was made this week at the 150th annual meeting of the academy in Washington, D.C.

The three new elections bring the number of living Caltech faculty members who belong to the academy to 73, including four foreign associates. In addition, three current members of the Caltech Board of Trustees are academy members.

In total, there are now 2,179 active members and 437 foreign associates of the National Academy of Sciences.

 

Michael E. Brown, the Richard and Barbara Rosenberg Professor and professor of planetary astronomy

Mike Brown is known for discovering and characterizing bodies at the edge of the solar system. In 2005, he discovered a Kuiper-belt object, later named Eris, which is about the same size as Pluto but 27 percent more massive. That finding led to a scientific debate over how to define a planet, and to the eventual demotion of Pluto to "dwarf planet."

Brown received his undergraduate degree from Princeton University in 1987 and did his graduate work at UC Berkeley, completing his PhD in 1994. He came to Caltech as a visiting associate in 1995 and joined the faculty in 1997. Brown became a full professor in 2005 and was named the Rosenberg Professor in 2008.

Brown has won numerous awards for his work, including the 2001 Harold C. Urey Prize from the American Astronomical Society's Division for Planetary Sciences, a Presidential Early Career Award, a Sloan Research Fellowship, and the 2012 Kavli Prize in Astrophysics.

 

Kenneth A. Farley, chair of the Division of Geological and Planetary Sciences and the W. M. Keck Foundation Professor of Geochemistry

Ken Farley is recognized for his studies of the noble gases and what their concentrations in marine sediments, rocks, minerals, and seawater can tell us about geochemical processes and the timescales over which these processes have operated. He is also currently a participating scientist on NASA's Mars Science Laboratory rover mission.

Farley received a BS from Yale University in 1986 and a PhD from UC San Diego in 1991. He joined the Caltech faculty in 1993 and was appointed professor in 1998. Farley was named the Keck Foundation Professor in 2003, the same year he served as director of the Tectonics Observatory. He became division chair in 2004.

His distinctions include the 1999 James B. Macelwane Medal of the American Geophysical Union, the 2000 National Academy of Science Award for Initiatives in Research, and the 2008 Arthur L. Day Medal from the Geological Society of America, and he was named a 2013 Geochemical Fellow by the Geochemical Society and the European Association of Geochemistry.

 

John H. Seinfeld, the Louis E. Nohl Professor and professor of chemical engineering

John Seinfeld's work has greatly improved our understanding of the origin, chemistry, and evolution of particles, or aerosols, in the atmosphere. He has revealed the role of organic species in aerosols and the process by which vapor molecules become incorporated into particles. Today, his work continues to focus on large questions such as the effects of aerosols on cloud formation and Earth's climate.

Seinfeld received his BS from the University of Rochester in 1964 and his PhD from Princeton University in 1967. He joined the faculty at Caltech that same year, becoming a full professor in 1974 and the Nohl Professor in 1979. He served as executive officer for chemical engineering from 1974 until 1990 and was chair of the Division of Engineering and Applied Science from 1990 until 2000.

Seinfeld is a member of the National Academy of Engineering and a fellow of the American Academy of Arts and Sciences. Among other distinctions, he won the Tyler Prize for Environmental Achievement in 2012, the American Chemical Society's Award for Creative Advances in Environmental Science and Technology in 1993, the Fuchs Award in 1998, the Nevada Medal in 2001, and the Stodola Medal from the Swiss Federal Institute of Technology in 2008. He has also received honorary doctorates from the University of Patras, Carnegie Mellon University, and Clarkson University.

 

The National Academy of Sciences is a private, nonprofit honorific society of distinguished scholars engaged in scientific and engineering research, dedicated to the furthering of science and technology and to their use for the general welfare. Established in 1863, the National Academy of Sciences has served to "investigate, examine, experiment, and report upon any subject of science or art" whenever called upon to do so by any department of the government.

For more information about the academy, or for the full list of newly elected members, visit www.nationalacademies.orgFor an extensive list of Caltech awards and honors, visit www.caltech.edu/content/awards-honors.

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Fifty Years of Clearing the Skies

A Milestone in Environmental Science

Ringed by mountains and capped by a temperature inversion that traps bad air, Los Angeles has had bouts of smog since the turn of the 20th century. An outbreak in 1903 rendered the skies so dark that many people mistook it for a solar eclipse. Angelenos might now be living in a state of perpetual midnight—assuming we could live here at all—were it not for the work of Caltech Professor of Bio-organic Chemistry Arie Jan Haagen-Smit. How he did it is told here largely in his own words, excerpted from Caltech's Engineering & Science magazine between 1950 and 1962. (See "Related Links" for the original articles.)

Old timers, which in California means people who have lived here some 25 years, will remember the invigorating atmosphere of Los Angeles, the wonderful view of the mountains, and the towns surrounded by orange groves. Although there were some badly polluted industrial areas, it was possible to ignore them and live in more pleasant locations, especially the valleys . . . Just 20 years ago, the community was disagreeably surprised when the atmosphere was filled with a foreign substance that produced a strong irritation of the eyes. Fortunately, this was a passing interlude which ended with the closing up of a wartime synthetic rubber plant. (November 1962)

Alas, the "interlude" was an illusion. In the years following World War II, visibility often fell to a few blocks. The watery-eyed citizenry established the Los Angeles County Air Pollution Control District (LACAPCD) in 1947, the first such body in the nation. The obvious culprits—smoke-belching power plants, oil refineries, steel mills, and the like—were quickly regulated, yet the problem persisted. Worse, this smog was fundamentally different from air pollution elsewhere—the yellow, sulfur-dioxide-laced smog that killed 20 people in the Pennsylvania steel town of Donora in 1948, for example, or London's infamous pitch-black "pea-soupers," where the burning of low-grade, sulfur-rich coal added soot to the SO2. (The Great Smog of 1952 would carry off some 4,000 souls in four days.) By contrast, L.A.'s smog was brown and had an acrid odor all its own.

Haagen-Smit had honed his detective skills isolating and identifying the trace compounds responsible for the flavors of pineapples and fine wines, and in 1948 he began to turn his attention to smog.

Chemically, the most characteristic aspect of smog is its strong oxidizing action . . . The amount of oxidant can readily be determined through a quantitative measurement of iodine liberated from potassium iodide solution, or of the red color formed in the oxidation of phenolphthalin to the well-known acid-base indicator, phenolphthalein. To demonstrate these effects, it is only necessary to bubble a few liters of smog air through the colorless solutions. (December 1954)

His chief suspect was ozone, a highly reactive form of oxygen widely used as a bleach and a disinfectant. It's easy to make—a spark will suffice—and it's responsible for that crisp "blue" odor produced by an overloaded electric motor. But there was a problem:

During severe smog attacks, ozone concentrations of 0.5 ppm [parts per million], twenty times higher than in [clean] country air, have been measured. From such analyses the quantity of ozone present in the [Los Angeles] basin at that time is calculated to be about 500 tons.

Since ozone is subject to a continuous destruction in competition with its formation, we can estimate that several thousand tons of ozone are formed during a smog day. It is obvious that industrial sources or occasional electrical discharges do not release such tremendous quantities of ozone. (December 1954)

If ozone really was to blame, where was it coming from? An extraordinary challenge lay ahead:

The analysis of air contaminants has some special features, due to the minute amounts present in a large volume of air. The state in which these pollutants are present—as gases, liquids and solid particles of greatly different sizes—presents additional difficulties. The small particles of less than one micron diameter do not settle out, but are in a stable suspension and form so-called aerosols.

The analytical chemist has devoted a great deal of effort to devising methods for the collection of this heterogeneous material. Most of these methods are based on the principle that the particles are given enough speed to collide with each other or with collecting surfaces . . . A sample of Los Angeles' air shows numerous oily droplets of a size smaller than 0.5 micron, as well as crystalline deposits of metals and salts . . . When air is passed through a filter paper, the paper takes on a grey appearance, and extraction with organic solvents gives an oily material. (December 1950)

Haagen-Smit suspected that this oily material, a complex brew of organic acids and other partially oxidized hydrocarbons, was smog's secret ingredient. In 1950, he took a one-year leave of absence from Caltech to prove it, working full-time in a specially equipped lab set up for him by the LACAPCD. By the end of the year, he had done so.

Through investigations initiated at Caltech, we know that the main source of this smog is due to the release of two types of material. One is organic material—mostly hydrocarbons from gasoline—and the other is a mixture of oxides of nitrogen. Each one of these emissions by itself would be hardly noticed. However, in the presence of sunlight, a reaction occurs, resulting in products which give rise to the typical smog symptoms. The photochemical oxidation is initiated by the dissociation of NO2 into NO and atomic oxygen. This reactive oxygen attacks organic material, resulting in the formation of ozone and various oxidation products . . . The oxidation reactions are generally accompanied by haze or aerosol formation, and this combination aggravates the nuisance effects of the individual components of the smog complex. (November 1962)

Professor of Plant Physiology Frits Went was also on the case. Went ran Caltech's Earhart Plant Research Laboratory, which he proudly called the "phytotron," by analogy to the various "trons" operated by particle physicists. (Phyton is the Greek word for plant.) "Caltech's plant physiologists happen to believe that the phytotron is as marvellously complicated as any of the highly-touted 'atom-smashing' machines," Went wrote in E&S in 1949. "[It] is the first laboratory in the world in which plants can be grown under every possible climatic condition. Light, temperature, humidity, gas content of the air, wind, rain, and fog—all these factors can be simultaneously and independently controlled. The laboratory can create Sacramento Valley climate in one room and New England climate in another." Most of Los Angeles was still orchards and fields instead of tract houses, and the smog was hurting the produce. Went, the LACAPCD, and the UC Riverside agricultural station tested five particularly sensitive crops in the phytotron, Haagen-Smit wrote.

The smog indicator plants include spinach, sugar beet, endive, alfalfa and oats. The symptoms on the first three species are mainly silvering or bronzing of the underside of the leaf, whereas alfalfa and oats show bleaching effects. Some fifty compounds possibly present in the air were tested on their ability to cause smog damage—without success. However, when the reaction products of ozone with unsaturated hydrocarbons were tried, typical smog damage resulted. (December 1950)

And yet a third set of experiments was under way. Rubber tires were rotting from the smog at an alarming rate, cracking as they flexed while rolling along the road. Charles E. Bradley, a research associate in biology, turned this distressing development into a cheap and effective analytical tool by cutting rubber bands by the boxful into short segments. The segments—folded double, secured with a twist of wire, and set outside—would start to fall apart almost before one could close the window. "During severe smog initial cracking appears in about four minutes, as compared to an hour or more required on smog-free days, or at night," Haagen-Smit wrote in the December 1954 E&S.

The conclusion that airborne gasoline and nitrogen oxides (another chief constituent of automobile exhaust) were to blame for smog was not well received by the oil refineries, who hired their own expert to prove him wrong. Abe Zarem (MS '40, PhD '44), the manager and chairman of physics research for the Stanford Research Institute, opined that stratospheric ozone seeping down through the inversion layer was to blame. But seeing (or smelling) is believing, so Haagen-Smit fought back by giving public lectures in which he would whip up flasks full of artificial smog before the audience's eyes, which would soon be watering—especially if they were seated in the first few rows. By the end of his talk, the smog would fill the hall, and he became known throughout the Southland as Arie Haagen-Smog.

By 1954, he and Frits Went had carried the day.

[Plant] fumigations with the photochemical oxidation products of gasoline and nitrogen dioxide (NO2) was the basis of one of the most convincing arguments for the control of hydrocarbons by the oil industry. (December 1954)

It probably didn't hurt that an outbreak that October closed schools and shuttered factories for most of the month, and that angry voters were wearing gas masks to protest meetings. By then, there were some two million cars on the road in the metropolitan area, spewing a thousand tons of hydrocarbons daily.

Incomplete combustion of gasoline allows unburned and partially burned fuel to escape from the tailpipe. Seepage of gasoline, even in new cars, past piston rings into the crankcase, is responsible for 'blowby' or crankcase vent losses. Evaporation from carburetor and fuel tank are substantial contributions, especially on hot days. (November 1962)

Haagen-Smit was a founding member of California's Motor Vehicle Pollution Control Board, established in 1960. One of the board's first projects was testing positive crankcase ventilation (PCV) systems, which sucked the blown-by hydrocarbons out of the crankcase and recirculated them through the engine to be burned on the second pass. PCV systems were mandated on all new cars sold in California as of 1963. The blowby problem was thus easily solved—but, as Haagen-Smit noted in that same article, it was only the second-largest source, representing about 30 percent of the escaping hydrocarbons.

The preferred method of control of the tailpipe hydrocarbon emission is a better combustion in the engine itself. (The automobile industry has predicted the appearance of more efficiently burning engines in 1965. It is not known how efficient these will be, nor has it been revealed whether there will be an increase or decrease of oxides of nitrogen.) Other approaches to the control of the tailpipe gases involve completing the combustion in muffler-type afterburners. One type relies on the ignition of gases with a sparkplug or pilot-burner; the second type passes the gases through a catalyst bed which burns the gases at a lower temperature than is possible with the direct-flame burners. (November 1962)

Installing an afterburner in the muffler has some drawbacks, not the least of which is that the notion of tooling around town with an open flame under the floorboards might give some people the willies. Instead, catalytic converters became required equipment on California cars in 1975.

In 1968, the Motor Vehicle Pollution Control Board became the California Air Resources Board, with Haagen-Smit as its chair. He was a member of the 1969 President's Task Force on Air Pollution, and the standards he helped those two bodies develop would eventually be adopted by the Environmental Protection Agency, established in 1970—the year that also saw the first celebration of Earth Day. It was also the year when ozone levels in the Los Angeles basin peaked at 0.58 parts per million, nearly five times in excess of the 0.12 parts per million that the EPA would declare to be safe for human health. This reading even exceeded the 0.5 ppm that Haagen-Smit had measured back in 1954, but it was a triumph nonetheless—the number of cars in L.A. had doubled, yet the smog was little worse than it had always been. That was the year we turned the corner, in fact, and our ozone levels have been dropping ever since—despite the continued influx of cars and people to the region.

Haagen-Smit retired from Caltech in 1971 as the skies began to clear, but continued to lead the fight for clean air until his death in 1977—of lung cancer, ironically, after a lifetime of cigarettes. Today, his intellectual heirs, including professors Richard Flagan, Mitchio Okumura, John Seinfeld, and Paul Wennberg, use analytical instruments descended from ones Haagen-Smit would have recognized and computer models sophisticated beyond his wildest dreams to carry the torch—a clean-burning one, of course—forward.

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Picking Apart Photosynthesis

New insights from Caltech chemists could lead to better catalysts for water splitting

PASADENA, Calif.—Chemists at the California Institute of Technology (Caltech) and the Lawrence Berkeley National Laboratory believe they can now explain one of the remaining mysteries of photosynthesis, the chemical process by which plants convert sunlight into usable energy and generate the oxygen that we breathe. The finding suggests a new way of approaching the design of catalysts that drive the water-splitting reactions of artificial photosynthesis.

"If we want to make systems that can do artificial photosynthesis, it's important that we understand how the system found in nature functions," says Theodor Agapie, an assistant professor of chemistry at Caltech and principal investigator on a paper in the journal Nature Chemistry that describes the new results.

One of the key pieces of biological machinery that enables photosynthesis is a conglomeration of proteins and pigments known as photosystem II. Within that system lies a small cluster of atoms, called the oxygen-evolving complex, where water molecules are split and molecular oxygen is made. Although this oxygen-producing process has been studied extensively, the role that various parts of the cluster play has remained unclear. 

The oxygen-evolving complex performs a reaction that requires the transfer of electrons, making it an example of what is known as a redox, or oxidation-reduction, reaction. The cluster can be described as a "mixed-metal cluster" because in addition to oxygen, it includes two types of metals—one that is redox active, or capable of participating in the transfer of electrons (in this case, manganese), and one that is redox inactive (calcium).

"Since calcium is redox inactive, people have long wondered what role it might play in this cluster," Agapie says.

It has been difficult to solve that mystery in large part because the oxygen-evolving complex is just a cog in the much larger machine that is photosystem II; it is hard to study the smaller piece because there is so much going on with the whole. To get around this, Agapie's graduate student Emily Tsui prepared a series of compounds that are structurally related to the oxygen-evolving complex. She built upon an organic scaffold in a stepwise fashion, first adding three manganese centers and then attaching a fourth metal. By varying that fourth metal to be calcium and then different redox-inactive metals, such as strontium, sodium, yttrium, and zinc, Tsui was able to compare the effects of the metals on the chemical properties of the compound.

"When making mixed-metal clusters, researchers usually mix simple chemical precursors and hope the metals will self-assemble in desired structures," Tsui says. "That makes it hard to control the product. By preparing these clusters in a much more methodical way, we've been able to get just the right structures."

It turns out that the redox-inactive metals affect the way electrons are transferred in such systems. To make molecular oxygen, the manganese atoms must activate the oxygen atoms connected to the metals in the complex. In order to do that, the manganese atoms must first transfer away several electrons. Redox-inactive metals that tug more strongly on the electrons of the oxygen atoms make it more difficult for manganese to do this. But calcium does not draw electrons strongly toward itself. Therefore, it allows the manganese atoms to transfer away electrons and activate the oxygen atoms that go on to make molecular oxygen.

A number of the catalysts that are currently being developed to drive artificial photosynthesis are mixed-metal oxide catalysts. It has again been unclear what role the redox-inactive metals in these mixed catalysts play. The new findings suggest that the redox-inactive metals affect the way the electrons are transferred. "If you pick the right redox-inactive metal, you can tune the reduction potential to bring the reaction to the range where it is favorable," Agapie says. "That means we now have a more rational way of thinking about how to design these sorts of catalysts because we know how much the redox-inactive metal affects the redox chemistry."

The paper in Nature Chemistry is titled "Redox-inactive metals modulate the reduction potential in heterometallic manganese-oxido clusters." Along with Agapie and Tsui, Rosalie Tran and Junko Yano of the Lawrence Berkeley National Laboratory are also coauthors. The work was supported by the Searle Scholars Program, an NSF CAREER award, and the NSF Graduate Research Fellowship Program. X-ray spectroscopy work was supported by the NIH and the DOE Office of Basic Energy Sciences. Synchrotron facilities were provided by the Stanford Synchrotron Radiation Lightsource, operated by the DOE Office of Biological and Environmental Research. 

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Theodor Agapie Named Cottrell Scholar

Research Corporation for Science Advancement (RCSA) has named Theodor Agapie, an assistant professor of chemistry at Caltech, a 2013 Cottrell Scholar.

The Cottrell Scholar Awards were instituted by RCSA in 1994 to recognize early-career individuals for innovative research and teaching excellence. The awards are named in honor of scientist, inventor, and philanthropist Frederick Gardner Cottrell who, in 1912, founded the organization that came to be known as RCSA.

"I am honored to have been selected as a Cottrell Scholar by RCSA," says Agapie. "I am grateful to my team of researchers and the greater Caltech community for a rewarding and stimulating environment in which to do science."

Using the natural world as a source of inspiration, Agapie's research group studies and develops molecular systems to solve problems related to energy, materials, and health. In addition to his lab-based research, Agapie actively works to bring together graduate, undergraduate, and high school students through an outreach program that includes career mentoring, designing new experiments, and organized visits to the Caltech campus.

Agapie, a native of Romania, received his bachelor's degree from MIT in 2001 and his PhD from Caltech in 2007. He has been an assistant professor at Caltech since early 2009. Since joining Caltech's faculty, Agapie has been named a Searle Scholar, a Sloan Research Fellow, and a recipient of a National Science Foundation CAREER Award, and he has received the Award in Pure Chemistry from the American Chemical Society.

 

 

 

 

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State Legislators Honor Frances Arnold

Caltech chemistry professor Frances Arnold will be honored by the California Legislative Women's Caucus at its inaugural Breaking the Glass Ceiling awards ceremony in Sacramento, California, on March 4.

The ceremony, to be held in the Assembly chambers at the California State Capital, is part of the Legislative Women's Caucus commemoration of Women's History Month. Following the ceremony, Arnold and other awardees will attend a reception at the governor's office.

"I am honored to be included in the Legislative Women's Caucus's Breaking the Glass Ceiling ceremony," says Arnold. "It is important for people to know that there is a place for women in science and that female scientists are appreciated for their role in society."

Arnold will be among a small group of women so honored. According to the Legislative Women's Caucus, the Breaking the Glass Ceiling ceremony commemorates "influential women who have made an incredible contribution to California and have inspired women and girls here and beyond."

Arnold is the Dick and Barbara Dickinson Professor of Chemical Engineering, Bioengineering and Biochemistry at Caltech. Her "directed evolution" research has led to the creation of biological catalysts that are useful in the production of biofuels and chemicals from renewable resources.

Arnold has won numerous awards. In December, she was named by the White House as a recipient of the 2011 National Medal of Technology and Innovation. President Barack Obama presented Arnold with her medal in a ceremony in the East Room of the White House on February 1.

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John Bercaw Wins 2012 Tolman Medal in Chemistry

The Southern California Section of the American Chemical Society (SCALACS) has selected John E. Bercaw, the Centennial Professor of Chemistry at Caltech, to receive the 2012 Tolman Medal.

According to SCALACS, the Tolman Medal honors chemists for "achievements in fundamental studies; achievements in chemical technology; significant contributions to chemical education; or outstanding leadership in science on a national level." Awardees need not be residents of Southern California, but their award-related accomplishments must have been made here.

"I am very honored to have been selected to receive the Tolman Medal," says Bercaw. "Awards such as the Tolman Medal help to inspire chemists to explore new areas of research and to help their fellow scientists."

Bercaw's research group at Caltech focuses on the development of new catalysts for producing polymers, fuels, and commodity chemicals. His group works in the area of organotransition metal chemistry and prepares new compounds, investigates their chemical reactivity, and defines the fundamental mechanisms by which they react. Bercaw's research has led to new catalysts that have been adopted by industry for producing new and improved polyethylenes, as well as to catalysts for upgrading plentiful molecules such as methane or other light hydrocarbons to produce gasoline or diesel fuel.

"As our fossil fuel resources dwindle, it is imperative that we find more efficient and greener ways to convert them into transportation fuels and materials such as plastics," says Bercaw.

Bercaw received his BS in chemistry from North Carolina State University in 1967 and a PhD in chemistry from the University of Michigan in 1971. He originally came to Caltech as an Arthur Amos Noyes Research Fellow in Chemistry in 1972. He was appointed assistant professor of chemistry in 1974, associate professor in 1977, and professor in 1979. Named Shell Distinguished Professor in 1985, then Centennial Professor in 1993, he served as executive officer for chemistry in the Division of Chemistry and Chemical Engineering from 1999 to 2002. Bercaw is a member of the National Academy of Sciences and the American Academy of Arts and Sciences.

The Tolman Medal is named in honor of Richard C. Tolman, who became professor of physical chemistry and mathematical physics at Caltech in 1921 and later dean of the graduate school. The list of previous Tolman Medal winners includes Caltech scientists Harry B. Gray, Linus C. Pauling, Jacqueline K. Barton, Ahmed Zewail, and Robert H. Grubbs.

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Visualizing Biological Networks in 4D

A unique microscope invented at Caltech captures the motion of DNA structures in space and time

PASADENA, Calif.—Every great structure, from the Empire State Building to the Golden Gate Bridge, depends on specific mechanical properties to remain strong and reliable. Rigidity—a material's stiffness—is of particular importance for maintaining the robust functionality of everything from colossal edifices to the tiniest of nanoscale structures. In biological nanostructures, like DNA networks, it has been difficult to measure this stiffness, which is essential to their properties and functions. But scientists at the California Institute of Technology (Caltech) have recently developed techniques for visualizing the behavior of biological nanostructures in both space and time, allowing them to directly measure stiffness and map its variation throughout the network.

The new method is outlined in the February 4 early edition of the Proceedings of the National Academy of Sciences (PNAS).

"This type of visualization is taking us into domains of the biological sciences that we did not explore before," says Nobel Laureate Ahmed Zewail, the Linus Pauling Professor of Chemistry and professor of physics at Caltech, who coauthored the paper with Ulrich Lorenz, a postdoctoral scholar in Zewail's lab. "We are providing the methodology to find out—directly—the stiffness of a biological network that has nanoscale properties."

Knowing the mechanical properties of DNA structures is crucial to building sturdy biological networks, among other applications. According to Zewail, this type of visualization of biomechanics in space and time should be applicable to the study of other biological nanomaterials, including the abnormal protein assemblies that underlie diseases like Alzheimer's and Parkinson's.

Zewail and Lorenz were able to see, for the first time, the motion of DNA nanostructures in both space and time using the four-dimensional (4D) electron microscope developed at Caltech's Physical Biology Center for Ultrafast Science and Technology. The center is directed by Zewail, who created it in 2005 to advance understanding of the fundamental physics of chemical and biological behavior.

"In nature, the behavior of matter is determined by its structure—the arrangements of its atoms in the three dimensions of space—and by how the structure changes with time, the fourth dimension," explains Zewail. "If you watch a horse gallop in slow motion, you can follow the time of the gallops, and you can see in detail what, for example, each leg is doing over time. When we get to the nanometer scale, that is a different story—we need to improve the spatial resolution to a billion times that of the horse in order to visualize what is happening."

Zewail was awarded the 1999 Nobel Prize in Chemistry for his development of femtochemistry, which uses ultrashort laser flashes to observe fundamental chemical reactions occurring at the timescale of the femtosecond (one millionth of a billionth of a second). Although femtochemistry can capture atoms and molecules in motion, giving the time dimension, it cannot concurrently show the dimensions of space, and thus the structure of the material. This is because it utilizes laser light with wavelengths that far exceed the dimension of a nanostructure, making it impossible to resolve and image nanoscale details in tiny physical structures such as DNA .

To overcome this major hurdle, the 4D electron microscope employs a stream of individual electrons that scatter off objects to produce an image. The electrons are accelerated to wavelengths of picometers, or trillionths of a meter, providing the capability for visualizing the structure in space with a resolution a thousand times higher than that of a nanostructure, and with a time resolution of femtoseconds or longer.

The experiments reported in PNAS began with a structure created by stretching DNA over a hole embedded in a thin carbon film. Using the electrons in the microscope, several DNA filaments were cut away from the carbon film so that a three-dimensional, free-standing structure was achieved under the 4D microscope.

Next, the scientists employed laser heat to excite oscillations in the DNA structure, which were imaged using the electron pulses as a function of time—the fourth dimension. By observing the frequency and amplitude of these oscillations, a direct measure of stiffness was made.

"It was surprising that we could do this with a complex network," says Zewail. "And yet by cutting and probing, we could go into a selective area of the network and find out about its behavior and properties."

Using 4D electron microscopy, Zewail's group has begun to visualize protein assemblies called amyloids, which are believed to play a role in many neurodegenerative diseases, and they are continuing their investigation of the biomechanical properties of these networks. He says that this technique has the potential for broad applications not only to biological assemblies, but also in the materials science of nanostructures.

Funding for the research outlined in the PNAS paper, "Biomechanics of DNA structures visualized by 4D electron microscopy," was provided by the National Science Foundation and the Air Force Office of Scientific Research. The Physical Biology Center for Ultrafast Science and Technology at Caltech is supported by the Gordon and Betty Moore Foundation.

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