Professor Emeritus Chiang Chung Mei, pioneering scholar of ocean wave dynamics and fluid mechanics, dies at 91

Chiang Chung "C.C." Mei, professor emeritus in the MIT Department of Civil and Environmental Engineering (CEE), a renowned hydrodynamicist whose work shaped the field’s understanding of ocean waves and their interactions with coastal and offshore structures, passed away peacefully at home in Waltham, Massachusetts, on July 16. He was 91. 

For more than four decades, Mei was a defining presence in CEE. Since joining the MIT faculty as an associate professor in 1965, he became one of the world's foremost authorities on theoretical hydrodynamics, fluid mechanics, and ocean and coastal wave phenomena, retiring in 2010 after 45 years on the faculty. Throughout his career, he earned a reputation among colleagues and students as a generous mentor and thoughtful leader.

An elegant, rigorous scholar

Mei's research advanced the science of ocean wave hydrodynamics, spanning nearly every aspect, including nearshore currents, sediment transport and resuspension, the formation of sand ripples and bars on beaches, wave-induced stresses and seabed deformation, and the removal of contaminants from soils. In later years, he extended his mathematical approach to biofluid dynamics, publishing on flow problems in blood vessels and the inner ear, including a paper on "Streaming and diffusion in the cochlea" that appeared in the Journal of Fluid Mechanics in July 2025.

He authored over 300 publications, was cited more than 14,000 times, and coauthored the landmark books "Theory and Applications of Ocean Surface Waves" and "Homogenization Methods for Multiscale Mechanics." Mei published decades of influential research on wave power extraction, harbor oscillations, waves over muddy seabeds, coastal vegetation, landslide-generated waves, tsunamis, and hydrodynamic resonance. His work combined mathematical elegance with practical engineering application and continues to guide solutions to some of the world's most complex ocean-based environmental challenges, including coastal defenses against storms and oil spill response strategies.

"C.C. tackled deep, diverse, difficult, and important fluid dynamics questions with utmost finesse and elegance," says Lydia Bourouiba, the Japan Steel Industry Professor. "He was an inspiring scholar, an intellectual leader, and a wonderful mentor, whose rigor set the standard we should continue to uphold. We lost a true giant in our field."

His excellence and leadership in research and teaching earned numerous prestigious recognitions, including a Guggenheim Fellowship in 1972, election to the National Academy of Engineering in 1986, fellowship in the American Physical Society, the Theodore von Kármán Medal in 2007, and appointment as a Ford Professor of Engineering at MIT. 

Beyond his scientific achievements, Mei devoted himself to the MIT community, serving as interim head of CEE from 2001 to 2002 and helping guide the department through a period of transition with the same humility and steadiness that characterized his scholarly contributions. In 2015, the department established the C.C. Mei Distinguished Speaker Series in his honor — an idea that grew out of the initiative of Bourouiba to revive CEE's environmental seminar series and honor its strong historical legacy in fluid dynamics. "Discussing the idea with C.C., he thought it was an excellent idea and was so generously supportive. He embodied the excellence I wanted the new series to reflect; naturally, we named it in his honor," she says. The series continues to bring internationally renowned scholars to MIT. 

A mentor whose students became family

Mei's influence was equally profound in the lives of his students. Over more than 45 years at MIT, Mei advised and mentored generations of engineers, many of whom became leaders in academia, industry, and government. Even in his final days, those relationships endured. 

One of his first doctoral students, Professor Emertius Ole Madsen, visited him just hours before his passing. Former student Yile Li SM '01, PhD '06, who continued collaborating with Mei on biofluid dynamics research in his later years, remained in close conversation with him throughout his final days. Li recalls the highlight of his discussions with Mei. "He told me there are three stages of doing research: solving problems using mathematical methods, modeling problems by capturing core physics, and ultimately discovering entirely new problems," Li says. "His own work proved he was a master of all three."

For Mei's family, MIT was never simply his workplace. "CEE was truly the center of my father's life," says his daughter Deborah Mei. "For more than 50 years, it shaped not just his career, but our whole family's world. His students, colleagues, and collaborators weren't separate from our home life — they were part of it, for as long as I can remember."

Colleagues consistently remember not only Mei's intellectual brilliance, but also his extraordinary generosity. Mei was known for the warmth he extended to junior colleagues finding their footing at MIT. 

"He was so respectful and kind to me when I was hired in 1976, and feeling like a fish out of water," says Institute Professor Sallie “Penny” Chisholm. "I will never forget that. A great gentleman, indeed." 

Heidi Nepf, the Donald and Martha Harleman Professor, recalls Mei as "an exceptional scholar and a wonderful colleague."

Rafael L. Bras, professor emeritus, remembers Mei as the model of the gentleman scholar. "He cared deeply about people, loved his profession, and touched countless lives, both directly and indirectly. Everybody loved him."

A full and joyful life

Mei was born on April 4, 1935, in Wuchang, Hubei Province, China, the only son and first child of Ju-Long Mei and Wu Yu-Ling. He earned his BS from National Taiwan University in 1955, his MS from Stanford University in 1958, and his PhD from Caltech in 1963.

Those who knew him describe a man who was passionate, playful, endlessly curious, and quick with both words and affection. The home he shared with his wife, Caroline, became a gathering place for generations of the Mei family, his MIT colleagues and students alike with animated conversation, humor, and his familiar loving banter with his wife and siblings, as those close to him remember it.

To generations of students and colleagues, Mei was known as much for his patience, kindness, intellectual curiosity, and quiet encouragement as for his scientific accomplishments. He was always willing to discuss an idea, help a student work through a difficult problem, or offer thoughtful guidance to a young colleague beginning an academic career. His legacy lives on not only in the theories that continue to shape coastal and ocean engineering, but also in the worldwide community of scholars he mentored, inspired, and welcomed over more than half a century at MIT.

Mei is survived by his wife, Caroline (Schmitt) Mei of Waltham; his daughter, Deborah Yupin Mei, and her husband, Juan Ignacio Garcia De Motiloa Ubis of Singapore; his sisters Helen Chiang-Hua Mei Chao of Potomac, Maryland; Teresa Chiang-Ming Mei Wu of Bethesda, Maryland; Heidi Chiang-Kuo Mei Hsia and her husband, Jack, of Potomac, Maryland; and Christine Chiang Ying Mei and her husband, Paul Tung, of Rancho Palos Verdes, California; his grandchildren, Juan Ignacio Jr. and Lauren; and many nieces, nephews, grand-nieces, and grand-nephews.

Gifts may be made in Mei's memory to the Chiang and Caroline Mei Fund 

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Drug that targets an inflammatory enzyme could help prevent lung cancer

Every year, lung cancer kills more than 100,000 people in the United States. Smoking is the leading risk factor for lung cancer, but other environmental exposures can also contribute to the disease.

In an advance that could help prevent some of those lung cancer deaths, MIT researchers have shown that blocking an enzyme involved in lung inflammation appears to reduce the risk of developing tumors. 

The researchers found that this enzyme, caspase-1, is active in developing tumors in mice. When they treated the mice with a small-molecule drug that inhibits caspase-1, the mice were much less likely to develop lung tumors.

That drug has already gone into clinical trials for other diseases, and the researchers now hope to test it as a preventative drug in people with elevated risk for lung cancer. 

“If you look at global cancer deaths, lung cancer causes most of them, and most of that is driven by tobacco smoking. Additionally, people who are ‘never smokers’ are showing up with lung cancer. You can imagine a future where you get a test and if you’re deemed high-risk, you go on a preventative medicine. This concept is called cancer interception, and it could help millions of people,” says Sangeeta Bhatia, the John and Dorothy Wilson Professor of Health Sciences and Technology and of Electrical Engineering and Computer Science at MIT, and a member of MIT’s Koch Institute for Integrative Cancer Research and the Institute for Medical Engineering and Science (IMES).

Bhatia is the senior author of the new study, which appears today in Science Advances. Cathy Wang PhD ’26 is the lead author of the paper. 

Blocking inflammation

Preventing lung cancer in patients who are at high risk could significantly reduce the death toll of the disease. In 2017, a clinical trial run by Novartis yielded a tantalizing hint that targeting lung inflammation could prevent some lung cancer cases. That trial, known as CANTOS, was designed to examine whether an anti-inflammatory drug — an antibody that blocks the cytokine IL-1 beta — could reduce the risk of strokes and heart attacks. Unexpectedly, the researchers found that this treatment led to lower rates of lung cancer in a subset of people.

Later trials showed that the antibody had little effect in patients who had established lung cancer, but researchers are still exploring the possibility of using it to prevent progression of lung cancer in high-risk patients. A recent study by the Swanton lab at the Francis Crick Institute identified a set of proteins, across several biological pathways and cell types, that could be used to predict which patients would respond to treatment with an IL-1 beta antibody. 

IL-1 beta requires protease cleavage to be converted to its mature, active form. Thus, Bhatia and her team wondered if enzymes called proteases, which cleave other proteins, might be involved in driving the inflammatory pathway that includes IL-1 beta.

For several years, Bhatia’s lab has been developing tools to track and visualize proteases, since the activity of these enzymes can contribute to cancer development. Proteases can help tumor cells escape their original locations by cutting through proteins of the extracellular matrix, and they also play essential roles in guiding inflammatory cell migration, which can influence tumor growth and immune system targeting.

By coming up with ways to detect these enzymes, Bhatia’s lab has created diagnostic nanosensors for cancer and other diseases. The sensors consist of nanoparticles decorated with peptides that can be cleaved by certain proteases, revealing when proteases are active in a particular tissue or disease state.

In addition to their role in cancer, proteases are known to be involved in the regulation of inflammation. In their new study, Bhatia and her colleagues adapted their nanosensors to identify proteases that may participate in IL-1 beta-mediated inflammatory pathways. 

“We know that proteases are very important in inflammation, and we wanted to pinpoint which ones might be the most active during early lung cancer development,” Wang says.

For this study, the researchers used a mouse model developed by Tyler Jacks, the David H. Koch Professor of Biology at MIT and a member of the Koch Institute. This model, known as KPS, is engineered to turn on cancer-causing mutations in the p53 and Kras genes. The mice also express a peptide called SIINFEKL, which helps to activate T cells and stimulate inflammation in the lung.

The researchers designed their experiments to allow them to model increased cancer risk, beginning before tumor formation was detectable. Five weeks after they induced the cancer-causing mutations, the researchers injected some of the mice with an antibody that blocks IL-1 beta, while others were untreated. Three weeks later, the researchers used their nanosensors to detect proteases that were active in the lungs. 

Those experiments showed that in untreated mice, which all developed lung tumors, caspase-1 was very active. However, in the treated mice, which had fewer tumors, caspase-1 activity was significantly reduced. The researchers also found that in untreated mice, the active caspase-1 was found primarily in lung tumors, not in nearby healthy tissue.

Working with Lecia Sequist, a professor of medicine at Havard Medical School and physician at Mass General Brigham, the researchers also analyzed a small number of human lung fluid samples. In these samples, they also found higher levels of caspase-1 activity from patients with lung cancer compared to healthy donors, despite a common smoking history.

A repurposed drug

The observation that caspase-1 activity is interrelated with the IL-1 beta inflammation pathway was not completely surprising, given IL-1 beta itself required protease cleavage to be converted to its mature, active form. The MIT team then investigated whether inhibitors of caspase-1 might also provide the same protective effects as inhibitors of IL-1 beta, or even improve them. 

Before tumors developed, the researchers began treating the at-risk KPS mice with either a caspase-1 inhibitor, an IL-1 beta antibody, or both. In mice that received both drugs, nearly 20 percent never developed tumors at all. In the mice that received either the caspase-1 inhibitor or the IL-1 beta antibody alone, tumors were much smaller and less numerous than in untreated mice.

Unlike antibodies, which need to be given intravenously, caspase-1 inhibitors can be taken orally, which could make them more appealing as a preventative treatment. Another opportunity provided by these drugs is that they have previously been tested in clinical trials for treatment of rheumatoid arthritis and other diseases.

“What’s so attractive about using this caspase-1 inhibitor is that it has actually been tested in humans. It’s already been through safety studies, and we think it could potentially be repurposed for cancer prevention,” Bhatia says.

The researchers hope to test the drug in a clinical trial, potentially using the biomarkers that were identified by the Swanton team to identify subjects who are likely responsive to IL-1 beta antibody treatment. 

The authors of the study also include MIT researchers Qian Zhong, Shih-Ting Wang, Carmen Martin-Alonso, Sofia Neaher, Sahil Patel, Tiziana Parisi, Jesse Kirkpatrick, and Tyler Jacks. 

The study was funded by Johnson & Johnson, Upstage Lung Cancer through the Koch Institute Frontier Research Program, the Virginia and D.K. Ludwig Fund for Cancer Research, the Koch Institute’s Marble Center for Cancer Nanomedicine, the Koch Institute Support (core) Grant from the National Cancer Institute, and a core center grant from the National Institute of Environmental Health Sciences. 

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Cells pulse together as they grow — and malignant cells pulse the longest

Epithelial cells are the tiny shields that line and protect our body. In a developing embryo, epithelial cells grow, divide, and move into positions to form the outer layers of our skin and the surfaces of our organs and blood vessels. When we scrape our skin, suffer an internal tear, or undergo surgery, epithelial cells will migrate to the site of injury to heal a wound. And when epithelial cells go haywire, they can turn malignant and spread through the body as cancer. 

MIT engineers have now discovered that as they migrate, epithelial cells can synchronize and collectively pulse. In a study appearing today in the journal Newton, the researchers report observing groups of epithelial cells repeatedly moving in, then out, like a circle of dancers coming together and pulling apart. 

The team measured this collective rhythmic pulsing in different types of epithelial cells, including healthy cells, cells from benign tumors, and cancerous cells. 

Surprisingly, they discovered that malignant epithelial cells were more persistent in their synchronization, pulsing together for twice as long as healthier cells. It’s unclear why the cells sync up in this way. But the researchers suspect that this cellular dance can serve as a clinical signal.

“More aggressive cancer cells tend to have a steadier and more persistent rhythm as compared to healthy ones,” says study author Ming Guo, professor of mechanical engineering at MIT. “We think this coordination could serve as an early warning sign of how likely a tumor is to spread. The same coordinated waves may help shape embryos during development and close wounds upon injury.”

The study includes first author and former MIT graduate student Wenhui Tang SM ’20, PhD ’24; Mehrana Nejad and L. Mahadevan of Harvard University; and Adrian Pegoraro of the Metrology Research Centre of the National Research Council Canada. 

Cells got rhythm

When studying how epithelial cells organize and develop into whole organs and tissues, scientists have focused mainly on how the cells coordinate in space. Where cells move, where they are in relation to the growing tissue, and where they end up, are questions of spatial coordination that scientists including Guo have looked to investigate. How the movement of cells relate over time is less well-understood. 

Guo’s group at MIT studies cell interactions to identify patterns that relate to healthy versus diseased states. As part of this work, the team takes microscopic snapshots of cells that they grow in the lab, to identify interesting behaviors among cells. Recently, Tang, then a member of Guo’s lab, was looking at a series of movies of epithelial cells when she started to see a rhythm, or pattern over time.

“I was studying collective cell migration, and I observed cells were swelling, then squeezing together, then swelling, again and again, forming local patterns,” Tang recalls. “That’s when I realized there might be something more interesting happening with these cells over time.”

Taking a pulse

In their new study, the researchers focused on the timing of cellular movements. They started by studying healthy, live epithelial cells that they cultured in the lab. They stained the cells with fluorescent dye to illuminate each cell’s nucleus. This way, they could easily identify one cell from another. They kept the cells in dishes with nutrients to help them naturally grow, divide, and move about. 

“We’re looking at their natural migration process, related to how they would migrate during different processes in the body, such as when forming skin and organs, and healing wounds,” Guo explains.

Using a confocal microscope, the team took snapshots of the cells every few minutes, for up to 30 hours. When they strung the images together as a sort of movie, a distinct pattern emerged. 

“If you just stare at any one location, you can see those dots are coming together, and then going further away, then coming together again, and going further away, like waves,” Tang says. 

They observed that a single pulse occurred over about an hour. This pulsing persisted in healthy cells, as a slow and steady rhythm over the 30-hour period. 

Curious as to whether other types of epithelial cells would sync up in similar fashion, the team tried the same experiment with several different lines of human breast cancer epithelial cells. They studied the movement of cells from benign tumors and cells of increasing malignancy. They observed similar pockets of synchronized pulsing in every cell type, especially in the most cancerous cells. 

“We found the really dangerous cancer cells team up over time, and do this persistent oscillation, twice as long as healthy cells,” Guo says. “This is unexpected. We see they really team up, synchronize, and oscillate together, which potentially facilitates their invasion.”

The researchers also observed a correlation between cell synchronization, and cell density: In each dish of cells, regardless of type, the cells continued to grow, divide, and pulse. As their numbers grew, more cells pulsed together, and their synchronization increased, up to a point. Once the cells reached a certain density, their pulsing began to die down.

“There’s a peak of synchrony before it decreases as cell density continues to increase,” Tang says.

This connection is especially interesting in the context of certain conditions such as asthma. Epithelial cells line the inside of many organs and tissues, including the airways. In healthy people, these cells pack together and “jam” up to form a solid, stable lining that protects the airways. In asthmatic airways, however, epithelial cells are less able to jam together. This results in airways that are loose and fragile, easily irritated, and difficult to heal. 

Guo and Tang suspect that, as there appears to be a connection between cell density and cell synchronization, there may be a way to target asthma treatments, by watching how potential drugs affect asthma cell synchronization. A similar approach could be taken for the screening of cancer drugs.

“More malignant cells would be better synchronized. After treating them with a drug, if their synchronization is disrupted, then it might be an efficient drug where we can consider the next step,” Guo envisions.

This research was supported, in part, by the National Institutes of Health.

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High-speed microscopy reveals electrical activity across the brain

Within the brain, neurons compute by generating electrical impulses. These signals travel throughout neurons, which are in turn connected in vast networks that control brain functions such as sensory perception, memory formation, and control of movement. 

In an advance that could help neuroscientists map those neural networks, leading to a better understanding of how neural activity underlies behavior and other brain functions, MIT engineers have invented a new microscope that can image electrical activity in neurons distributed across the brain of an entire organism, the experimental model Danio rerio (zebrafish).

Using a microscope that they adapted for fast, high-volumetric rate imaging, the researchers were able to track electrical activity across the brain on the scale of milliseconds. This method revealed patterns of neural activity from neurons throughout the brain that were activated in response to ultraviolet light.

“All of the parts of the brain are connected together, so if you want to truly understand the brain, you have to understand how all the neurons work together as an emergent whole,” says Ed Boyden, the Y. Eva Tan Professor in Neurotechnology at MIT; a professor of biological engineering, media arts and sciences, and brain and cognitive sciences; and a member of MIT’s McGovern Institute for Brain Research, Yang Tan Collective, and the Koch Institute for Integrative Cancer Research.

Boyden is the senior author of the study, which appears today in Nature Methods. Former J. Douglas Tan Postdoctoral Fellow Zeguan Wang PhD ’24 and former MIT postdoc Jie Zhang are the lead authors of the paper. Other authors include former MIT postdoc Panagiotis Symvoulidis, Picower Institute research scientist Wei Guo, graduate students Davy Deng and Lige Zhang, Koch Institute research scientist Adam Amsterdam, Picower Institute research scientist Takato Honda, Boston College undergraduate Steven Roche, and Matthew Wilson, the Sherman Fairchild Professor of Neuroscience at MIT and a member of the Picower Institute.

High-speed imaging

One technique often used to measure neuron activity in the brain is calcium imaging. Calcium flows into neurons after they fire an electrical impulse, so measuring calcium levels in the cells can serve as a proxy for neural activity. However, this type of imaging isn’t fast enough to capture single spikes of activity.

“Calcium imaging inherently is very slow, so you’re talking about imaging activity on the order of seconds or even minutes. Typically that is too slow for us to be able to see a lot of these high-speed neural activities,” Zhang says. “Neurons compute using electrical activity, so with voltage imaging, you can get direct observation of that.” 

To enable direct imaging of voltage, researchers have developed proteins called genetically encoded voltage indicators — fluorescent proteins that can be genetically expressed in neurons. When a neuron fires an impulse, the protein fluoresces, which can be detected with a fluorescence microscope.

In previous work, researchers have used these proteins to image small populations of neurons, usually focusing on one localized part of the brain. Until now, there hasn’t been a way to image a large volume, such as the entire brain, with the millisecond-scale resolution needed to see electrical impulses from individual neurons.

To achieve that, the MIT team decided to modify a commonly used microscope known as a light sheet microscope. This type of microscope uses a sheet of laser light to illuminate a thin slice of a sample. By imaging many layers in sequence, this technique can generate 3D images of a large volume. However, with previous microscopes, the scanning of an entire volume would take too long to be able to capture neuronal impulses across the volume at single cell resolution. 

“Different groups of neurons that are distributed across the brain coordinate together at millisecond timescales to generate a lot of behaviors and brain computations,” Wang says. “To understand the principles, we need the technology to observe their activity at the same time, across the whole brain, so we are not missing any important participant neurons.”

To make the imaging process fast enough to image millisecond-scale activity, the researchers increased the image acquisition speed of the microscope’s camera, and they also boosted the scanning speed of the microscope using a technique called remote refocusing.

Using this approach, the researchers showed that they could scan the entire zebrafish brain 200 times per second, or once every five milliseconds. 

Mapping brain activity

To test the new microscope, the researchers engineered neurons in larval zebrafish to express a voltage indicator called Positron2-Kv. Although they had hoped that the indicator would end up in every neuron, it produced signals in neurons distributed throughout the brain, with about one quarter of the neurons exhibiting acceptable signals. This was enough, however, to observe patterns of activity across the brain. The researchers imaged the brain as the fish were resting, and they were able to observe single voltage spikes from neurons, as well as rapid bursts of spikes.

Additionally, this technique revealed patterns in how the brain is activated following a stimulus such as ultraviolet light. Immediately following the stimulus, activity was seen in the optic tectum, which receives and processes visual input from the retina. This activity propagated from one side of a part of the brain called the tectum to the other. Stimulus-independent activity also occurred in sequences across sets of neurons in the cerebellum and hindbrain.

The researchers now hope to increase the percentage of neurons that they can image across the brain, as well as the microscope’s speed and resolution. They are also working on expanding the use of this technique to other experimental models, including mice.

This approach, they say, could offer neuroscientists a new way to generate hypotheses about what happens in the brain when it engages in specific behaviors, or about how brain activity is linked to states of mind such as daydreaming.

“A big question is simply to understand how neurons work together as a network. And this might be the first time that you could do that, because you can image the voltage of neurons distributed throughout the network,” Boyden says.

The research was funded by the National Institutes of Health, the BRAIN Initiative, the Picower Institute Innovation Fund, K. Lisa Yang, Ashar Aziz, the K. Lisa Yang and Hock E. Tan Center for Molecular Therapeutics in Neuroscience at MIT, the Hock E. Tan and K. Lisa Yang Center for Autism Research, the Alana Down Syndrome Center, John Doerr, Jed McCaleb, James Fickel, and the Howard Hughes Medical Institute.

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Researchers uncover hidden pore network within nuclear fuel

The moment a nuclear reactor begins operation, a complex chain of events is initiated within the fuel: Heavy atoms split into fission products, knocking other atoms out of place and creating defects that can change how the fuel swells, transfers heat, and reacts chemically over time. 

Understanding those processes is key to understanding how safe and efficient a nuclear reactor will be. But even for some of the most-studied fuel types, the mechanisms controlling those processes are unclear.

Such is the case with a particular kind of metallic fuel, uranium alloyed with 10 percent zirconium by weight, also known as U-10Zr. This fuel was extensively tested in historic sodium-cooled fast reactors such as the Experimental Breeder Reactor-II (EBR-II) in Idaho and the Fast Flux Testing Facility (FFTF) in Washington state, helping establish the foundation for metallic fuel development in the U.S. Today, U-10Zr is again attracting attention for use in next-generation advanced reactors.

But most studies of U-10Zr took place decades ago, leaving unanswered questions about exactly how the fuel changes when it undergoes nuclear fission in a reactor and how it interacts with the protective fuel cladding surrounding it.

Now, together with Idaho National Laboratory (INL), MIT researchers have led one of the most detailed three-dimensional studies of irradiated U-10Zr to date. The researchers used a technique known as high energy synchrotron X-ray computed tomography at Brookhaven National Laboratory (BNL) in New York to analyze the pore networks and chemical changes that formed under irradiation during use inside the FFTF reactor, providing new insights into how the material swells, transfers heat, and interacts with the fuel cladding. 

The findings could help keep some nuclear reactors running for longer, while also informing the next generation of nuclear reactor fuel systems.

“This study helps us model the pore distribution in the fuel more accurately,” says senior author Ericmoore Jossou, MIT’s John Clark Hardwick (1986) Professor of Nuclear Science and Engineering. “It also helps us design for the safe operation of metallic fuels in reactors by giving us a better understanding of the role of pores and their importance.”

Joining Jossou on the paper are first author and MIT postdoc Anthony Harrup; Riley Moeykens ’25, SM ’25; BNL researchers Michael Drakopoulos and Nghia Vo; and INL researchers Jana Howard, Colby Jensen, and Tiankai Yao.

Understanding nuclear fuel

A class of nuclear reactors known as sodium-cooled fast reactors generate energy from rods of metallic fuels that are sealed inside metal tubes called cladding. In each rod, heat generally moves outward from the center to the edge and then to the cladding, where liquid sodium carries heat away to be harvested into power.

“As you operate the reactor, the contact between the fuel and the cladding material creates chemical interactions that can be problematic,” explains Jossou. “There is a migration of materials from the fuel to the cladding, like fission gases and rare earth elements called lanthanides, which can react with the cladding, cause embrittlement, and damage the fuel system.”

Studies of previously irradiated fuel and its cladding have captured mostly two-dimensional snapshots, preventing scientists from seeing the full scale of the pore networks that influence heat transfer and transport materials like lanthanides. Previous studies also mainly focused on specific sections of the fuel system, such as the fuel center or the fuel cladding interface.

For their study, the MIT researchers used fuel samples from the Fast Flux Testing Facility reactor, a sodium-cooled fast neutron reactor located in Washington state that operated from 1982 to 1992.

The Idaho National Lab managed the samples and prepared the samples. The team studied the prepared samples using high-energy synchrotron X-ray tomography at the Brookhaven National Laboratory. The synchrotron generated high-energy X-rays that allowed the researchers to reconstruct the fuel’s internal pore networks in three dimensions, revealing how porosity, chemistry, and fuel-cladding interactions evolve across the fuel radius.

The researchers found porosity increased modestly from the center of the fuel toward the fuel edge, but pore density jumped by over two orders of magnitude at the fuel’s edge by the cladding. The researchers also characterized the size and shape of pores, finding small pores at the center that turn into larger pore networks pointing outward toward the edge.

“The pores are currently modeled as spheres; however, in reality they are more complex, especially when many pores merged together,” Harrup says. “That’s true from the center all the way to the cladding. It explains why the cladding reacts the way it does, and why we see cladding chemicals in the fuel.”

The pore networks toward the edge allow fission products and lanthanides to move but slow down heat transport, impacting the fuel’s performance and lifetime. The researchers also mapped their microstructural findings with changes in the chemistry of the fuel in different areas.

“With this study, we’ve conducted an in-depth analysis enabled by advanced computational imaging methods that has never been done before, with correlations between local chemical environments and the formation of pores,” Harrup says. “It turns out that whether the environment is uranium rich or zirconium rich impacts the morphology and the channels of the pores. That has never been reported before.”

“The ability to directly visualize pore connectivity and fuel cladding interaction in three dimensions gives us important insight for improving fuel performance for advanced metallic fuel for sodium fast reactors,” says Tiankai Yao of INL.

Informing reactor designs

The experimental findings differed from some models of how pores form and how the fuel system swells, which could improve simulations to help keep reactors running for longer. They also give a more nuanced picture of how pores influence reactor performance and safety.

“This helps optimize the current metallic fuel proposed for sodium fast reactors,” Jossou says. “Now, together with INL, we better understand how pores are influencing the thermal performance of metallic fuel in reactors. At high temperature, the pores are not all bad, because we found they act as pathways for liquid sodium metal to flow through the fuel and sustain thermal conductivity. Connected pores could also serve as releasing channels for fission gases which reduce the internal fuel matrix stress.”

The findings could also be used to design better fuel systems for next generation of sodium fast reactors.

“This excellent piece of work generated by Professor Jossou’s group in collaboration with INL and BNL has elegantly combined the strength of attenuation-based X-ray tomography and focused ion beam lift-outs and produced valuable insights to the location-specific 3D porosity distribution in neutron-irradiated U-10Zr fuel,” says Dong Liu, a professor at Oxford University who was not associated with this work. “What is also impressive is that they correlated 3D porosity to the thermal properties of the fuels: The total volume fraction is not the only parameter that is important, the 3D topology also matters. This is extremely informative for the study of other types of porous nuclear materials.”

The work was supported by the U.S. Department of Energy Office of Nuclear Energy and utilized resources at BNL and INL. The sample preparation was carried out at INL, which is part of the Nuclear Science User Facilities, through a Rapid Turnaround Award.

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MIT selected to lead new NSF materials research center

The National Science Foundation (NSF) has selected MIT to establish and lead a new Materials Research Science and Engineering Center (MRSEC) focused on materials technologies for medical imaging, sustainable metals production, and next-generation semiconductors, according to an NSF announcement released July 30.

Expected to provide $18 million in research funding over six years, the award brings together 16 research groups from nine departments across four institutions, including five MIT departments, three collaborating universities, and a teaching hospital. The award is pending MIT’s negotiation of a formal research agreement with the NSF.

The MIT Materials Research Science and Engineering Center will be directed by Associate Professor Rafael Jaramillo of the Department of Materials Science and Engineering (DMSE), with Professor Caroline Ross of DMSE serving as associate director. The center will be housed administratively within the MIT Materials Research Laboratory.

The center will have two main research thrusts. One will engineer specialized materials to advance X-ray detectors used in medical imaging, potentially leading to better cancer diagnosis, lower radiation exposure, and improved industrial and security imaging. The other will explore high-temperature sulfur-based molten materials to transform how metals and semiconductors are made, opening a path to more efficient metal production, improved access to critical materials, and new thin-film semiconductor technologies. 

The expected funding will also support a new shared laboratory for testing magnetic materials and materials under extreme conditions, managed by MIT.nano. This facility will be available to academic and industry users, expanding the nationwide portfolio of NSF-supported research facilities. 

“The long-term goal is for the broader materials and engineering community to see the disruptive potential of bringing researchers together across disciplines to solve complex challenges,” says Jaramillo, the Stavros V. Salapatas Career Development Professor of Materials Science and Engineering. “And that includes specifically in medical diagnostics and metals production, where entirely new things will be possible that aren’t considered possible today.”

A legacy of collaboration

The selection of MIT’s MRSEC is part of a $108 million NSF investment in six research centers that will explore a range of topics, including artificial intelligence-driven experimental laboratories and hybrid quantum materials that combine light and matter. NSF’s MRSEC program brings together interdisciplinary teams of researchers to push the boundaries of materials science and engineering and tackle complex scientific challenges.

The MIT center builds on nearly 60 years of interdisciplinary materials research at the Institute, extending a legacy that began with U.S. Department of Defense-supported laboratories in the 1960s and continued through NSF-funded centers in subsequent decades. Past MRSEC investments helped build research communities that enabled MIT centers of excellence such as the MIT Microphotonics Center and the Microsystems Technology Laboratories.

“We were inspired to continue that legacy of collaborative research in materials science,” Jaramillo says. “It’s mainly the mode of working — the mode of working in a very intentional way as a team across disciplinary boundaries and having this program that brings people together.”

MIT departments involved in the MRSEC include DMSE; Chemistry; Chemical Engineering; Earth, Atmospheric and Planetary Sciences (EAPS); and Physics. Collaborating institutions identified in the MRSEC proposal are Yale University, the University of California at Santa Barbara, and the Department of Radiology at Massachusetts General Hospital and Harvard Medical School. 

The first research group will focus on re-engineering scintillators — materials that convert X-rays into visible light — at the nanoscale, with the goal of improving resolution, speed, and energy sensitivity.

“My vision for that is really Marin and JJ’s vision. So I'm basically cheerleading for them,” Jaramillo says, referring to optical materials experts Professor Marin Soljačić of Physics and Professor Juejun Hu of DMSE, who are expected to lead the effort.

The second group is closer to Jaramillo’s own research in semiconductor and advanced electronic materials. It seeks to develop a deeper understanding of high-temperature sulfur-based liquids to improve the yield and efficiency of producing critical metals such as copper. Expertise in these types of materials has become increasingly rare in U.S. academia, Jaramillo says, and one goal of the center is to rebuild that capability at MIT. “I’m very excited about that being a new intellectual center of gravity.”

Telling stories about materials

Beyond research, the center is also expected to develop outreach activities highlighting the importance of materials science in society, particularly in the Boston region, where Jaramillo said industries need more workers with backgrounds in materials processing.

“For example, our community colleges don’t offer it,” Jaramillo says. “If you were looking at a community college in Michigan, everyone would know what materials science is.”

One initiative, DISASTER! — “with all caps and an exclamation mark,” Jaramillo says — will tell stories of real-world catastrophes and the materials failures that contributed to them.

A major part of materials science over the last century has been understanding why things fail, Jaramillo says. “It’s also a tremendous foot in the door for introducing the field. Because frankly, ‘if it bleeds, it leads.’ If you have giant disasters, then suddenly people are like, ‘Why did the bridge fail?’”

The program will encourage MIT undergraduates to research and tell these stories, illustrating how forensic materials science has helped prevent future failures.

Among the examples Jaramillo cited are the rivets used to assemble the RMS Titanic, whose impurities made the rivets more brittle in the freezing North Atlantic, and the crashes of the world’s first commercial jetliner, the de Havilland Comet, which revealed the dangers of metal fatigue.

“There are so many other stories that need to be told around how a material failed,” Jaramillo said. “It really cost people money and time and lives. And then through forensic materials science, we understood why it failed and we avoided future failures.”

The MRSEC team is planning to stage public outreach events at the MIT Future Fest.

Looking ahead six years, Jaramillo hopes the center will have become a self-sustaining hub for materials research. 

“I hope that we will have rebuilt the muscle memory to come together in an interdisciplinary way around materials science, and that it should have a bit of a self-sustaining element to it. I hope that we then compete successfully for the next center, and lay the groundwork for the next 60 years.”

MIT Research Administration Services supported the MRSEC proposal development through its Research Development team, which specializes in providing substantive assistance for large and complex research proposals, and in supporting early-career faculty.

MIT faculty expected to be involved in the MRSEC are Rafael Jaramillo, Caroline Ross, Juejun Hu, and Antoine Allanore of DMSE; Moungi Bawendi of Chemistry; Martin Bazant of Chemical Engineering; Nicole Nie and Shuhei Ono of EAPS; and Marin Soljačić, Riccardo Comin, Nuh Gedik, and Long Ju of Physics.

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Astronomers discover a brand-new type of astrophysical object: A black hole star

Astronomers at MIT and elsewhere have spotted an extremely bright red spot in the early universe. The object resembles an enormous star, spanning the size of our solar system. But it also is putting out 100 billion times more energy than any known star can physically produce. In fact, such energies are closer to what a black hole might generate.

The curious combination suggests that the red spot is an entirely new type of astrophysical source. The astronomers are calling it a “black hole star.”

In a paper appearing today in the journal Nature, the team presents their analysis of the new object, which they discovered using NASA’s James Webb Space Telescope (JWST). The telescope spotted the bright red dot in the very early universe, just a few hundred million years after the Big Bang.

The scientists conclude that the most likely explanation for the strange red dot is that it is a mashup of a black hole and a star — a combination that has never been observed until now. The object is likely a hugely dense cloud of gas, powered not by standard nuclear fusion, but by a central black hole.

“Our picture of this object is evolving very rapidly,” says lead author Rohan Naidu, a NASA Hubble Fellow and Pappalardo Fellow at MIT’s Kavli Institute for Astrophysics and Space Research (MKI). “We think there is a central black hole that is 100,000 times as massive as the sun. And around this black hole, there would be this very extended envelope of gas that looks like a star the size of the solar system. It’s huge.”

If the bright red dot is indeed a black hole star, it would help to solve the identity of other mysterious “little red dots” that have appeared in nearly every deep space image JWST has taken to date.

“These little red dots seem to be everywhere in the early universe but essentially disappear by the present day,” Naidu says. “What exactly these objects are has been one of the most debated topics of the JWST era.”

The study’s MIT co-authors are MKI Director Robert Simcoe, the Bruno B. Rossi Professor of Experimental Physics; and Wendy Sun ’26, along with collaborators from multiple other institutions.

A singular source

Naidu and his colleagues didn’t intend to find a black hole star. They were looking for the most distant, earliest galaxies, as part of a survey that they named “Mirage or Miracle” (MoM). The team used the JWST to look into deep space, back when the universe was a few hundred million years old. Their goal was to look for galaxies that actually formed at those early times.

“There’s been this puzzle of many bright galaxies showing up at extremely early times,” Naidu says. “What we found was that what looks like an extremely bright early galaxy, aka a ‘miracle,’ in some cases actually could be a ‘mirage.’”

As they looked through JWST’s images for intriguing sources to target with their survey, they noticed a feature that stood out from the rest: a dot that was very red, and very bright.

“When we see something very red in the universe, we often assume that it is surrounded by dust, like soot or ash,” Simcoe explains. “The same way that the wildfire smoke from Canada recently made the sky in Boston look bright red, astronomical objects can also appear redder than their intrinsic color when you see them through a veil of dust.”

But there were other signatures in the light that didn’t quite match up with what physicists expect from dust. The team also observed another strange pattern: The dot’s light was extremely bright, except below certain wavelengths, where the light completely disappeared. 

This spectral drop-off is known as a “Balmer break” — a signature traditionally associated with dense gas soaking up photons in the atmospheres of stars that are a few hundred millions of years old. Vega, one of the brightest stars in the night sky shows exactly this pattern. 

“The break we observed in this object is the deepest break we have ever observed in any object, ruling out ‘ordinary’ stars as the source,” Naidu says. “But it made us wonder if we were seeing a new kind of ‘stellar atmosphere,’ but on a spectacular scale.” 

What’s more, the red dot’s light contained almost no signature of metals or any elements other than hydrogen and helium. “It was truly singular in so many ways,” Naidu says.

Pure light

To puzzle out what the source of the red dot could be, the team ran simulations of different scenarios to see what combination of astrophysical features could produce the red dot’s distinctive color.

“We started to ask: Could you make something that red using just hydrogen, without any dust?” Simcoe says. “To our surprise, it turns out you can, if you have an extremely dense screen of hydrogen, so dense that it looks more like the surface of an enormous star than a wispy interstellar nebula.”

Their simulations pointed to the red dot possibly being some powerful enshrouded energy source, surrounded by an extremely dense cocoon of hydrogen. If this were the case, it would explain the light-blocking Balmer break and the lack of anything other than hydrogen and helium that the astronomers observed. But it still wouldn’t explain the object’s extreme brightness.

“You have something that looks a bit like a star but is 100 billion times brighter,” Naidu says. “That means you can’t be powering this by nuclear fusion, which is the energy source that sits at the heart of all the stars we have.”

Black holes, however, routinely produce energy at the scales the team observed. Naidu and his colleagues incorporated an active, accreting black hole into their simulations of the hydrogen-cocooned star and varied the black hole’s mass, along with other parameters. They then compared the resulting brightness of the simulated “black hole star” with the brightness that JWST observed from the red dot.

From these simulations, they found the closest match, and concluded that the most likely scenario to explain the red dot, is a black hole star. Specifically, the object likely contains a central black hole that is about 100,000 times as massive as the sun. This powerful core is surrounded by a dense, star-like cocoon of hydrogen that is roughly the size of the solar system.

The team has named the object MoM-BH*-1, after the survey that detected it, as well as the moniker “black hole star – one,” which implies that the object is the first of others. The researchers suspect that black hole stars could explain many of the other little red dots that appear in JWST images. Those objects are not as bright as MoM-BH*-1. 

“Every little red dot is consistent with being a black hole star, embedded in a generic early galaxy,” Naidu says. “But what is special about MoM-BH*-1 is, the black hole star is essentially completely outshining its surrounding host galaxy, such that we’re seeing pure black hole star light.”

This research was supported, in part, by the MIT Department of Physics, NASA, and the Space Telescope Science Institute.

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