Tam on STEAM

For a quiet girl growing up in the peaceful Los Angeles suburb of Chatsworth, reading opened up an amazing world.

Jenny Yang made a trek to the library each week to check out a stack of books. Fiction was her favorite, but she also liked reading about science. “I just liked learning about the world,” she said.

The more Yang read about the world, the more she thought about things like pollution and recycling. “I have felt since I was a kid that I was an environmentalist,” she said. “I felt there was a big responsibility to keep our planet healthy by having as little impact as possible.”

Now Yang has found a career that merges her curiosity about the world and her passion for protecting our Earth. As an assistant professor of chemistry at the University of California, Irvine, she creates catalysts that can be used in clean energy technologies. Catalysts are handy substances that speed up chemical reactions. The catalysts themselves don’t change in the process, so they can do their work again and again.

Yang is a rising star in her field. She has been honored with a National Science Foundation Career Award, a Hellman Foundation Faculty Fellowship, and the Department of Energy Early Career Award. She also has become a mentor to other young women building careers in chemistry.


Even as a young girl, Yang was drawn to science. Reading about the inventions of Leonardo da Vinci fired her imagination. And she spent hours leafing through an anatomy book her parents had. “I wanted to know, what is your appendix for? What are your tonsils for? Why do you have hair, and what is it made of?” she recalled.

In high school, her favorite class was chemistry. She loved spending Saturdays at special chemistry labs offered at her school.

Some teens like chemistry because of the potential for loud and smelly explosions, but Yang didn’t feel that way. “That scares me a bit,” she said. “I wasn’t that kind of adventurous person.”

Instead, what captured her imagination was learning about the elements that make up everything around us. “I liked to understand the laws that governed the world,” she said.


Yang’s dad is an electrical engineer, and both of her parents encouraged her to go into a STEM field. She decided to attend the University of California, Berkeley, and major in chemistry.

In her freshman year, Yang found a research position in a geochemistry lab. Her lab group was trying to figure out how contaminants from nuclear waste sites move through the soil above the water table. Right away, she was hooked.

“I fell in love with research,” she said. “It was just neat to me that that there was a mystery that we were trying to solve.” She remembers asking her supervisor in the lab, “How do I do this for a living?”

Working in another chemistry lab at Berkeley, Yang synthesized magnetic metal clusters that could be spun up or down. These molecular magnets had potential applications in data storage. She was excited by the idea of making new molecules. “I remember thinking it was so cool to have a new compound in a vial that doesn’t exist anywhere else in the Universe,” she said.

While she was an undergraduate, Yang had summer internships at Lawrence Berkeley National Laboratory and the National Renewable Energy Laboratory in Colorado. The experience at NREL awakened her interest in finding alternatives to fossil fuels.


Yang received her B.S. in chemistry in 2001. For graduate school, she headed across the country to the Massachusetts Institute of Technology. There she worked under Daniel Nocera, a leader in the chemistry of renewable energy.

Yang’s research involved synthesizing molecules that mimic reactions catalyzed by enzymes in our bodies. One of these reactions breaks down hydrogen peroxide before it can damage our cells. “We studied the fundamental reactions,” Yang explained. “Most of the work I do is very fundamental chemistry. But we often look to biology for inspiration.”

At MIT, most of Yang’s classmates were male, but she found ways to network with other female students. “I played women’s ice hockey, and that ended up being very good for me,” she said. “It got me out of the lab to meet other women on campus.”

Yang received her Ph.D. in inorganic chemistry in 2007. She did postdoctoral work at the Pacific Northwest National Laboratory in Washington State and became a staff scientist there. In 2011 she moved back to California to join the Joint Center for Artificial Photosynthesis at the California Institute of Technology.


While Yang was at Cal Tech, UC Irvine recruited her. University officials were eager to bring on this up-and-coming researcher. They also were committed to having more women on their faculty. They told Yang about the school’s commitment to women and to work-life balance. She joined UC Irvine in 2013 as an assistant professor, teaching classes and running her own lab.

Yang and her lab group work to develop metal catalysts for the production of fuels from clean energy sources. One goal is to find better catalysts to break apart water (H2O) so the hydrogen (2H) can then be used in nonpolluting fuel cells.

(See Solving Our Clean Energy Puzzle for more on Jenny Yang’s research.)

Yang is drawn to clean energy research for a couple of reasons. “It’s an interesting chemistry problem, but it’s also very important,” she said. “We have to move beyond fossil fuels and find something that is sustainable.”


An important part of Yang’s job is mentoring her students to help them become successful scientists. She is excited about the promise of the young women she sees choosing careers in chemistry. “My lab group is more than half women,” she noted. “I wasn’t intending to do that. It sort of just happened.”

Yang finds that young women often need extra encouragement to keep going in a traditionally male-dominated field like chemistry. When a female student is feeling insecure about her abilities, Yang will offer a pep talk.

“I tell them that you don’t have to know everything,” she said. “There’s a misconception that you have to be the best and the most brilliant to make a contribution to science, but that’s not true. As long as you have ideas to share, you can make a contribution.”

Yang also encourages up-and-coming scientists through a program called LEAPS (Laboratory Experiments and Activities in the Physical Sciences). Twice a year, middle school students from underserved communities visit UC Irvine labs.

In Yang’s lab, the young visitors do an experiment where they coat a penny with zinc to turn it silver. Then they heat the penny to form a bronze alloy, which turns the penny gold. At the end of the day, the students fill out a survey. “The survey asks what was the most memorable part of their day, and it’s really exciting to me when the students say it was one of our experiments,” Yang said.

“Our intention is to show them not only what it’s like to attend a university, but also to experience hands-on science,” she explained. “We keep the ratio of students to scientists very small so they can actually talk to the students.”


When she’s not working, Yang like to play sports and exercise with her husband, Robert Nielsen, a computational chemist at Cal Tech. Maintaining a good work-life balance is important to Yang. “There’s a macho attitude that if you want to do this job, you have to dedicate your life to science,” she said. “I don’t think that’s necessary or even healthy.”

Yang and her husband are expecting their first child soon. “It’s still not super common for women to have children at all before tenure,” she said. “I had some anxiety about that, but I have found that my colleagues have been very supportive.”

What advice does Yang have for young people aspiring to STEM careers? “The most important thing is to follow your curiosity and your passion,” she said. “There may be barriers. But what matters is following something that you care about.”

Learn about UC Irvine’s efforts to encourage women in STEM fields: https://goo.gl/AdlZJS


One of the biggest challenges we face is finding ecofriendly alternatives to fossil fuels. Jenny Yang’s lab at the University of California, Irvine, is working on a key piece of that clean energy puzzle.

Most of our activities—from driving cars and cooking meals to taking hot showers and watching our favorite TV shows—rely on fossil fuels. But these fuels—coal, oil, and natural gas—have huge downsides. They are nonrenewable. Also, burning them releases carbon dioxide, a greenhouse gas. As people burn more and more fossil fuels, the level of carbon dioxide in our air rises. This warms our planet, creating problems for living things all over the world.

To replace fossil fuels, many scientists are working on clean, renewable energy sources such as solar energy. “But solar energy is only available during the day,” Yang noted. “We don’t have a good way to store the energy so we can use it at night or when it’s cloudy.”

To solve this problem, Yang’s team is taking inspiration from nature. Plants (and a few single-celled creatures) have an amazing ability. They can change the Sun’s energy into chemical energy. During photosynthesis, plants capture the energy in sunlight and store it in the chemical bonds of sugar molecules. This sugar fuels everything plants do—from growing and reproducing to making more leaves, flowers, and seeds.

The fossil fuels we use today come mostly from the decayed remains of plants that used photosynthesis to store solar energy millions of years ago. “We are interested in replicating that process by using artificial photosynthesis to turn renewable solar energy into fuels,” Yang said. Yang’s lab group is developing catalysts to make this process feasible. Catalysts speed up chemical reactions that would otherwise be very slow. Yang and her colleagues make new chemicals from common metals. Then they test these chemicals to see how well they work as catalysts.

The simplest fuel is hydrogen. It is clean and renewable. One way to obtain hydrogen is to use solar energy to separate the “H” from H2O—water. Scientists have come up with catalysts to spur this reaction. But these catalysts are expensive or inefficient. Yang’s group is looking for new catalysts that are cheaper and better.

Another cutting-edge area of research is recycling carbon dioxide from the atmosphere. This is just what plants do during photosynthesis—they take carbon dioxide out of the air and use solar energy to turn it into fuel. Yang and her team are working on catalysts to mimic this process.

Fuels from recycled carbon dioxide could replace the carbon-based fuels we currently dig out of the ground. Burning these new fuels would still release carbon dioxide, but we would be recycling the same carbon dioxide instead of adding more to the air.

Yang hopes the push to “make like a plant” will help solve our clean energy puzzle. The goal is to generate plenty of clean fuel from renewable energy sources. “And that,” Yang said, “will lead to cleaner air with less impact on the environment.”

Since black holes are invisible, Ghez explained, “The tool that we use is to watch stars that orbit a black hole.” There’s a problem, though. Earth’s atmosphere distorts our view of those distant stars.

Ghez compares the challenge to looking at a pebble at the bottom of a moving river. She needed to find a way, in effect, to make the “river” stand still.

In 1995, Ghez and a team of graduate students began using the Keck telescope to track the stars. They used infrared wavelengths to see through the heavy dust near the galaxy’s center, some 26,000 light-years away. They also developed a new technique called adaptive optics.

To overcome the atmosphere’s distortion, they aimed a powerful laser toward the sky to create an artificial “star” in the direction of the real star they wanted to observe. A computer tracked the distortion of the laser’s “star.” Then astronomers could correct for atmospheric distortion by shifting the surface of a flexible mirror. “It’s kind of like very fancy eyeglasses for your telescope,” Ghez said.

Her team returned to the Keck telescope over months and years, capturing images that they put together to create time-lapse “movies” of the stars’ movements. But it was slow work. It took five years of measurements just to confirm that the star closest to the galaxy’s center had turned a corner in its orbit.

At first the team worked on the mountaintop, struggling with the effects of high altitude. After a few years, they were able to control the telescope from the observatory’s facility at sea level in Waimea. Today they can operate the Keck telescope from UCLA.

To prove the existence of a supermassive black hole, Ghez said, “I want to see the stars that are as close to the center of the galaxy as possible, because I want to show there is a mass inside as small a region as possible.“

The researchers traced the movement of about two dozen stars orbiting at incredible speeds. They were able to follow one particular star, called S0-2, through its entire 16-year orbit.

Their measurements showed that S0-2 and other stars were orbiting something with an immense mass—equivalent to 4 million suns—in a relatively small area—as big as our solar system. It almost had to be a supermassive black hole. “There are no other alternatives that we know of,” Ghez said.

The confirmation was a breakthrough but not a surprise. But there was one big surprise in what Ghez and her team saw. Some of the stars were young. New stars should not exist near a black hole. In theory, any cloud of gas and dust would be torn to shreds before it could form a star. Ghez and other astronomers still can’t explain the presence of such young stars.

Recently Ghez has tracked a mysterious object called G2, discovered in 2011. Some astronomers thought it was a huge cloud of hydrogen gas. But then G2 swung past the supermassive black hole without being torn apart. That meant it could not be a gas cloud. Ghez concluded G2 is probably a pair of binary stars pulled together by intense gravity to form one huge star enveloped in gas and dust.

Ghez is looking forward to a unique opportunity in 2018, when the star S0-2 makes its closest approach to the galactic center. Scientists predict that a black hole will cause deviations from general relativity—Albert Einstein’s theory of gravity. This theory says gravity results from the distortion of space and time. Objects of greater mass cause more distortion of space-time.

“One of our ambitions is to test general relativity around a supermassive black hole,” Ghez said. S0-2’s close encounter with the galactic center will give her this chance.

Ghez continues to search for ways to get a clearer view of the heart of the Milky Way. “The technology keeps advancing,” she said. “With every step forward, we can see more and more.”

Photo Credit: Kyle Alexander