Molinero | College of Science

National Academy of Sciences

May 4, 2022

Valeria Molinero elected as a member of the National Academy of Sciences.

Molinero is the Jack and Peg Simons Endowed Professor of Theoretical Chemistry and the director of the Henry Eyring Center for Theoretical Chemistry. She is a theoretical chemist and uses computer and statistical models to explore the science of how crystals form and how matter changes from one phase to another down to the atomic scale.

Much of her work has involved the transition between water and ice and how that transition occurs in the formation of clouds, in insects with antifreeze proteins, and in food products, especially those containing sugars. Her work has implications for any process in which control of the formation and growth of ice crystals is critical, including snowmaking at ski resorts, protection of crops from freezing, preservation of human organs and tissue for transplant, and production of ice cream and gelato, her favorite food. In 2020, she and her international colleagues demonstrated that the smallest possible nanodroplet of water that can freeze into ice is around 90 molecules, a finding that earned them the 2020 Cozzarelli Prize from the journal Proceedings of the National Academy of Sciences.

She is a fellow of the American Academy of Arts & Sciences and recipient of several U awards, including the Distinguished Scholarly and Creative Research Award in 2019, the Extraordinary Faculty Achievement Award in 2016, the Camille Dreyfus Teacher-Scholar Award in 2012 and the College of Science Myriad Faculty Award for Research Excellence in 2011. She has also been honored by the Beckman Foundation with its Young Investigator Award, and by the International Association for the Properties of Water and Steam with its Helmholtz Award.

Valeria Molina

"There’s satisfaction that comes from seeing someone grow from the beginning of the Ph.D. into an accomplished researcher."

Valeria heard about her election between the news of a new publication with postdoctoral scholar Debdas Dhabal and preparations for a doctoral student’s dissertation defense. She received a phone call from colleague Dale Poulter, a distinguished professor emeritus and National Academy of Sciences member, to announce her election. “I was shocked,” she says. “To say it was a surprise would not do it justice. It was fantastic.”

Minutes later, she went into the dissertation defense, reflecting on the range of accomplishments represented by the publication, the election and the defense. “All the research is made essentially there, in the work of the students and postdocs,” she says. “There’s satisfaction that comes from seeing someone grow from the beginning of the Ph.D. into an accomplished researcher.”

Molinero is among 120 U.S. scientist-scholars and 30 foreign associates elected at the Academy’s Annual Meeting in Washington, D.C. She joins 16 other current University of Utah researchers who’ve been elected to the Academy. The National Academies, which also include the National Academy of Engineering and National Academy of Medicine, recognizes scholars and researchers for significant achievements in their fields and advise the federal government and other organizations about science, engineering and health policy. With today’s elections, the number of National Academy of Sciences members stands at 2,512, with 517 foreign associates.

Past & Present

National Academy of Sciences:
Brenda Bass, Cynthia Burrows, Mario Capecchi, Dana Carroll, Thure Cerling, James Ehleringer, Kristen Hawkes, James O’Connell, Baldomero “Toto” Olivera, C. Dale Poulter, Peter Stang, Wesley Sundquist, Polly Wiessner, Henry Harpending, Jesse D. Jennings, Erik Jorgensen, Cheves Walling, Sidney Velick, John R. Roth, Josef Michl, Ray White, Julian Steward, Jeremy Sabloff, Henry Eyring and Louis Goodman and Mary C. Beckerle.
National Academy of Engineering:
Jindrich Kopecek, R. Peter King, Adel Sarofim, Sung Wan Kim, Gerald Stringfellow, Donald Dahlstrom, George Hill, Jan D. Miller, Milton E. Wadsworth, Thomas G. Stockham, John Herbst, Stephen C. Jacobsen, Willem J. Kolff, Alex G. Oblad, Anil Virkar and William A. Hustrulid.
National Academy of Medicine:
Mario Capecchi, Wendy Chapman, Sung Wan Kim, Vivian Lee, Baldomero “Toto” Olivera, Stephen C. Jacobsen, Eli Adashi, Paul D. Clayton and Homer R. Warner.

Distinguished Research

May 10, 2019

“Since Professor Molinero joined the Department of Chemistry as Assistant Professor in 2006, she has developed a thriving research program in physical and materials chemistry, with foci on elucidating the phase behavior of water and its impact on atmospheric processes, and the design of new materials for energy and cryopreservation. Professor Molinero’s ground breaking research at the University of Utah has already resulted in over 290 presentations at conferences, universities, and research institutions all over the world (110 of them by students and postdocs of Molinero), and 95 journal articles—including three in Nature—that have gathered almost five thousand citations,” said one nominator.

“Professor Molinero’s work is a hallmark of what research and scholarship at our University should be about. In her 12 years of independent research, she has made an indelible mark in several fundamental areas of physical and computational chemistry, with implications that extend to atmospheric sciences and the design of materials for energy and catalysis. Professor Molinero is a leader in the Chemistry and Physics communities. She is the Vice-chair and Chair-elect of the Theory subdivision of the American Chemical Society, member of the nominating committee of the Division of Chemical Physics of the American Physical Society, member of the Board of Managers of the American Institute of Physics Publishing, the Editorial Advisory Board of the Journal of Chemical Physics and of The Journal of Physical Chemistry, has been on the selection committee of major awards by the American Chemical Society…”

Insects, Bacteria & Ice

January 10, 2019

Valeria Molinero

Contrary to what you may have been taught, water doesn’t always freeze to ice at 32 degrees F (zero degrees C). Knowing, or controlling, at what temperature water will freeze (starting with a process called nucleation) is critically important to answering questions such as whether or not there will be enough snow on the ski slopes or whether or not it will rain tomorrow.

Nature has come up with ways to control the formation of ice, though, and in a paper published in the Journal of the American Chemical Society University of Utah professor Valeria Molinero and her colleagues show how key proteins produced in bacteria and insects can either promote or inhibit the formation of ice, based on their length and their ability to team up to form large ice-binding surfaces. The results have wide application, particularly in understanding precipitation in clouds.

“We’re now able to predict the temperature at which the bacterium is going to nucleate ice depending on how many ice-nucleating proteins it has,” Molinero says, “and we’re able to predict the temperature at which the antifreeze proteins, which are very small and typically don’t work at very low temperatures, can nucleate ice.”

What is ice nucleation?
It’s long been known that life likes to mess with ice. Insects, fish and plants all produce various forms of antifreeze proteins to help them survive in below-freezing conditions. And plant pathogens, particularly the bacterium Pseudomonas syringae, employ proteins that promote the formation of ice to induce damage in their hosts. Before we can talk about how these proteins work, though, we need a quick refresher on how ice freezes.

Pure water, with no impurities, won’t freeze until it reaches -35 degrees C (-31 degrees F). That’s the temperature at which the water molecules will spontaneously arrange into a crystal lattice and start to recruit other molecules to join in. To start the freezing process at warmer temperatures, however, water molecules need something to hold on to, like a speck of dust, soot or other impurity, on which it can start building its crystal lattice. This is the process called nucleation.

Ice-nucleating proteins, such as those in Ps. syringae, bind to nascent ice crystallites in such a way as to reduce the energy cost of additional freezing. They can also aggregate together to further enhance their nucleating power. “It is a lot of group work!” Molinero says.

These proteins can be so efficient that they can nucleate ice at temperatures as warm as -2 degrees C (29 degrees F). Ice-nucleating proteins are already being put to use at ski resorts, with Colorado-based Snomax International marketing an additive containing Ps. syringae that gives snowmaking machines a boost.

Antifreeze proteins, however, also bind to ice, but force it to develop a curved surface that discourages additional freezing and requires much colder temperatures for ice to grow. Also, antifreeze proteins don’t aggregate together. “They have evolved to be loners, as their job is to find ice and stick to it,” Molinero says.

All of this was previously known, including the fact that antifreeze proteins were relatively small and ice-nucleating proteins were relatively large. What wasn’t known, though, was how the sizes and aggregating behaviors of the proteins affected the temperature of ice nucleation. That’s the question Molinero and her team set out to answer.

A “single bullet”
Molinero and graduate students Yuqing Qiu and Arpa Hudait conducted molecular simulations of protein interactions with water molecules to see how they affected the temperature of ice nucleation. Antifreeze and ice-nucleating proteins, Molinero says, bind to ice with nearly equal strength.

“Nature is using a single bullet in terms of interactions to address two completely different problems,” she says. “And the way it has resolved between antifreeze or ice nucleation is by changing the size of the proteins and their ability to team up to form larger ice-binding surfaces.”

Antifreeze proteins, they found, nucleated at just above -35 degrees C, which matched experimental data. Lengthening the simulated proteins increased the nucleation temperature, which plateaued after a certain length. The simulations predicted that further assembling around 35 bacterial proteins into larger domains was key to reach the ice-nucleating performance of Ps. syringae, with a nucleation temperature of -2 degrees C (29 degrees F).

“Now we can design new proteins or synthetic materials that nucleate ice at a specific temperature,” Molinero says.

Why it matters
The implications of such a finding extend all the way to the future of water on Earth.

Precipitation begins as ice, which nucleates and grows until it’s heavy enough to precipitate. At high altitudes where it’s colder, soot and dust can do the job of triggering nucleation. But at lower altitudes, it’s not dust that triggers nucleation—it’s bacteria.

Yes, the same proteins in Ps. syringae that aid snowmaking at ski resorts also aid ice formation at warmer temperatures, allowing low-altitude clouds to precipitate. In a warming climate, Molinero’s findings can help climate modelers better understand the conditions of cloud formation and precipitation and forecast how warming will affect the amount of ice nucleation and precipitation in the future.

“The ability to predict whether the clouds are going to freeze or not is super important in climate models, because ice formation determines precipitation and also the ratio of solar energy absorbed and reflected by our atmosphere,” Molinero says. “The challenge to predict whether ice is going to nucleate or not in clouds is a major limitation the predictive ability of weather and climate models.”

At a much smaller scale, however, the antifreeze and ice-nucleating proteins can be employed together in a fine-tuned ice dance: Some insects use antifreeze proteins to protect themselves down to around -8 degrees C (18 degrees F), but then employ ice-nucleating proteins at lower temperatures to contain ice growth before it gets out of hand.

“The big picture is that we now understand how proteins use their size and aggregation to modulate how much they can nucleate ice,” Molinero says. “I think that this is quite powerful.”