Five from MIT elected to the National Academy of Sciences for 2021

The National Academy of Sciences has elected 120 new members and 30 international associates, including five professors from MIT — Dan Freedman, Robert Griffin, Larry Guth, Stephen Morris, and Gigliola Staffilani — in recognition of their “distinguished and continuing achievements in original research.” Current membership totals 2,461 active members and 511 international associates. Membership is one of the highest honors that a scientist can achieve.

The National Academy of Sciences is a private, nonprofit institution that was established under a congressional charter signed by President Abraham Lincoln in 1863. It recognizes achievement in science by election to membership, and — with the National Academy of Engineering and the National Academy of Medicine — provides science, engineering, and health policy advice to the federal government and other organizations.

Daniel Freedman

Daniel Freedman, professor emeritus in MIT’s departments of Mathematics and Physics, is also a visiting professor at Stanford University’s Institute for Theoretical Physics. Freedman's research is in quantum field theory, quantum gravity, and string theory, with an emphasis on the role of supersymmetry. More recently, one focus of his work is the AdS/CFT correspondence, a broad framework based on the equivalence of field theories in different spacetime dimensions, one with and one without gravity.

He received his BA from Wesleyan University in 1960, and his MS and PhD in physics from the University of Wisconsin in 1962 and 1964. Freedman held postdoctoral appointments at Imperial College, the University of California at Berkeley, and Princeton University before joining the faculty at the Institute of Theoretical Physics at SUNY Stony Brook. In 1980 he joined the MIT faculty in applied mathematics, and has been jointly appointed with the MIT theoretical physics faculty since 2001.

Freedman was a distinguished alumni fellow at the University of Wisconsin-Madison, was a former Sloan and Guggenheim fellow, and was named Fellow of the American Academy of Arts and Sciences and of the American Physical Society. He has received the Special Breakthrough Prize in Fundamental Physics, the Dirac Medal and Prize, and the Dannie Heineman Prize.

Larry Guth

Claude E. Shannon Professor of Mathematics Larry Guth’s research interests are in metric geometry, with a focus on systolic inequality, and on finding connections between geometric inequalities and topology. More recently, Guth has been researching harmonic analysis and combinatorics, in relation to the Kakeya problem, an open question in Euclidean geometry that connects with restriction-type estimates in Fourier analysis and with estimates about incidences of lines in extremal combinatorics.

Guth received his BS in mathematics from Yale University, and after receiving his PhD from MIT in 2005, he followed a postdoctoral position at Stanford with faculty appointments at the University of Toronto and the Courant. He joined the MIT math faculty in 2012. 

Guth received the Salem Prize in Mathematics for outstanding contributions to analysis, the Maryam Mirzakhani Prize in Mathematics, the American Mathematical Society's Bocher Prize, and the New Horizons in Mathematics Prize. He received the School of Science’s Teaching Prize in Graduate Education, and was named a Margaret MacVicar Faculty Fellow for exceptional undergraduate teaching.

Stephen Morris

Stephen Morris, the Peter A. Diamond Professor in Economics, is an economic theorist who has made important contributions to the foundations of game theory and mechanism design, as well as applications in macroeconomics, international economics, and finance. He has developed new ways of understanding and modeling the role of incomplete information in the economy, and its implications for analysis and policy.

Morris received his undergraduate degree in mathematics and economics at Cambridge University, and his PhD from Yale University. He taught at the University of Pennsylvania, Yale University, and Princeton University before joining MIT’s Department of Economics in 2019. 

Morris is a fellow and was president of the Econometric Society. He is a member of the American Academy of Arts and Sciences, a research fellow of the Center for Economic Policy Research, and was a Sloan Research and Guggenheim Fellow.   

Gigliola Staffilani

Gigliola Staffilani, the Abby Rockefeller Mauzé Professor of Mathematics, is a mathematical analyst whose research focuses on dispersive nonlinear partial differential equations. She is one of 59 new members who are women, the most elected to the NAS in a single year.

Staffilani received the BS equivalent from the University of Bologna in 1989, and MS and PhD degrees from the University of Chicago in 1991 and 1995. She held positions at Princeton, Stanford, and Brown universities, and joined MIT in 2002.   

She is a member of the Massachusetts Academy of Sciences, the American Academy of Arts and Sciences, and the National Academy of Sciences. She received a Guggenheim Fellowship and a Simons Fellowship in Mathematics, and is a fellow of the American Mathematical Society. At MIT, she received the inaugural MITx Prize for Teaching and Learning in MOOCs by the MIT Office of Digital Learning, the Earll M. Murman Award for Excellence in Undergraduate Advising, and the "Committed to Caring" award by the Office of Graduate Education.

Robert Guy Griffin

Robert Guy Griffin, the Arthur Amos Noyes Professor of Chemistry, is also director of the Francis Bitter Magnet Laboratory. He devotes a large fraction of the Griffin Group’s research efforts to develop new magnetic resonance techniques to study molecular structure and dynamics. He also develops high-field dynamic nuclear polarization for the study of biological solids.

Griffin received his BS in 1964 from the University of Arkansas, and his PhD from Washington University in 1969. He joined the Francis Bitter Magnet Laboratory in 1972, and the Department of Chemistry’s faculty in 1989.

He was awarded the Richard R. Ernst Prize in Magnetic Resonance, sponsored by the Bruker BioSpin Corporation, for his pioneering contributions to high-resolution solid-state nuclear magnetic resonance as a whole, as well as its applications to biological systems. In particular, Griffin has developed widely used techniques for dipolar recoupling that permit internuclear distances to be measured during so-called “magic angle” spinning experiments. 

He has also received the ISMAR (International Society of Magnetic Resonance) Prize, the Günther Laukien Prize for NMR research, and the Bijvoet Medal of the Bijvoet Center for Biomolecular Research of Utrecht University.

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Robotic solution for disinfecting food production plants wins agribusiness prize

The winners of this year’s Rabobank-MIT Food and Agribusiness Innovation Prize got a good indication their pitch was striking a chord when a judge offered to have his company partner with the team for an early demonstration. The offer signified demand for their solution — to say nothing of their chances of winning the pitch competition.

The annual competition’s MIT-based grand-prize winner, Human Dynamics, is seeking to improve sanitation in food production plants with a robotic drone — a “drobot” — that flies through facilities spraying soap and disinfectant.

The company says the product addresses major labor shortages for food production facilities, which often must carry out daily sanitation processes.

“They have to sanitize every night, and it’s extremely labor intensive and expensive,” says co-founder Tom Okamoto, a master’s student in MIT’s System Design and Management (SDM) program.

In the winning pitch, Okamoto said the average large food manufacturer spends $13 million on sanitation annually. When you combine the time sanitation processes takes away from production and delays due to human error, Human Dynamics estimates it’s tackling an $80 billion problem.

The company’s prototype uses a quadcopter drone that carries a tank, nozzle, and spray hose. Underneath the hood, the drone uses visual detection technology to validate that each area is clean, LIDAR to map out its path, and algorithms for route optimization.

The product is designed to automate repetitive tasks while complementing other cleaning efforts currently done by humans. Workers will still be required for certain aspects of cleaning and tasks like preparing and inspecting facilities during sanitation.

The company has already developed several proofs of concept and is planning to run a pilot project with a local food producer and distributor this summer.

The Human Dynamics team also includes MIT researcher Takahiro Nozaki, MIT master’s student Julia Chen, and Harvard Business School students Mike Mancinelli and Kaz Yoshimaru.

The company estimates that the addressable market for sanitation in food production facilities in the country is $3 billion.

The second-place prize went to Resourceful, which aims to help connect buyers and sellers of food waste byproducts through an online platform. The company says there’s a growing market for upcycled products made by companies selling things like edible chips made from juice pulp, building materials made from potato skins, and eyeglasses made from orange peels. But establishing a byproduct supply chain can be difficult.

“Being paid for byproducts should be low-hanging fruit for food manufacturers, but the system is broken,” says co-founder and CEO Kyra Atekwana, an MBA candidate at the University of Chicago’s Booth School of Business. “There are tens of millions of pounds of food waste produced in the U.S. every year, and there’s a variety of tech solutions … enabling this food waste and surplus to be captured by consumers. But there’s virtually nothing in the middle to unlock access to the 10.6 million tons of byproduct waste produced every year.”

Buyers and sellers can offer and browse food waste byproducts on the company’s subscription-based platform. The businesses can also connect and establish contracts through the platform. Resourceful charges a small fee for each transaction.

The company is currently launching pilots in the Chicago region before making a public launch later this year. It has also partnered with the Upcycled Food Association, a nonprofit focused on reducing food waste.

The winners were chosen from a group of seven finalist teams. Other finalists included:

• Chicken Haus, a vertically integrated, fast-casual restaurant concept dedicated to serving locally sourced, bone-in fried chicken;
• Joise Food Technologies, which is 3-D printing the next-generation of meat alternatives and other foods using 3-D biofabrication technology and sustainable food ink formulation;
• Marble, which is developing a small-footprint robot to remove fat from the surface of meat cuts to achieve optimal yield;
• Nice Rice, which is developing a rice alternative made from pea starch, which can be upcycled; and
• Roofscapes, which deploys accessible wooden platforms to “vegetalize” roofs in dense urban areas to combat food insecurity and climate change.

This was the sixth year of the event, which was hosted by the MIT Food and Agriculture Club. The event was sponsored by Rabobank and MIT’s Abdul Latif Jameel World Water and Food Systems Lab (J-WAFS).

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David Miliband SM ’90 warns of “age of impunity” for despotic governments around the globe

Former British foreign minister David Miliband SM ’90 offered a sobering warning about human rights and democracy while delivering a special MIT lecture on Wednesday — and outlined how we might confront the emerging “age of impunity,” in which authoritarian governments and even democracies are increasingly flouting the rule of law.

“The next decade promises to be a race or a fight between accountability and impunity, within our own countries and internationally,” Miliband said, noting that lawlessness on the part of and within countries “applies in politics, in economics, even in respect of the environment.” About 68 percent of the world’s population is now living under autocratic rule, representing a 20 percentage point increase over the last decade, he said. According to the Economist Intelligence Unit index, about 70 percent of the world’s countries, including many democracies, saw a reduction in political freedom last year.

This does not just mean fewer rights for citizens at home during peacetime, Miliband emphasized, but fewer rights for refugees, and for civilians caught in the middle of wars.

And yet, Miliband contended while giving MIT’s Muh Alumni Award Lecture, “The coming age of impunity is only inevitable if we let it be so.” Instead, he suggested, by deploying “countervailing power” from government, civil society, and the private sector, supporters of rights can begin to curb the ominous trend toward authoritarianism.

Miliband’s talk occurred after he received the 2021 Robert A. Muh Alumni Award in the School of Humanities, Arts, and Social Sciences. The honor was founded and endowed by Robert A. Muh ’59 and his wife Berit, and is granted by MIT’s School of Humanities, Arts, and Social Sciences (SHASS). Muh is a life member emeritus of the MIT Corporation, and founded the award to honor “extraordinary contributions” in the humanities, arts, and social sciences. Melissa Nobles, the Kenin Sahin Dean of the Humanities, Arts, and Social Sciences at MIT, introduced Muh at the event.

Miliband served as U.K. foreign secretary from 2007 to 2010; he was also a member of Parliament in Britain from 2001 to 2013 and served as secretary of state for the environment. Miliband received his undergraduate degree from Oxford University in 1987 and his master’s from MIT’s Department of Political Science. For the last several years, Miliband has been serving as president and CEO of the International Rescue Committee (IRC), based in New York.

As Miliband noted in his remarks, this is not the first talk he has delivered at MIT; he also gave MIT’s 2010 Compton Lecture, about the prospects for peace in Afghanistan, while serving as foreign secretary. Miliband’s remarks on Wednesday were very much shaped by his work with the IRC, which has helped refugees globally.

“There is a clear trend of growing international lawlessness and normlessness,” Miliband said, noting that there are now 34,000 civilians killed in warfare every year, double the number of five years ago, and almost 80 million refugees and displaced people around the world, a record. There are also increasing numbers of aid workers killed per year and more military strikes on hospitals.

Part of the reason for this, Miliband suggested, is a global “shift in the balance of power” away from democracy and toward authoritarian states, whose leaders believe that “what goes on within a state is the business of that state and that state alone.  This has weakened the ability of the international system to enforce and uphold the basic pillars of the international order,” such as the Geneva Conventions.

Thus “there is a vicious circle in play,” he observed, in which more authoritarian countries are likely to violate human rights, while feeling less outside pressure to adhere to basic norms.

Yet ultimately, Miliband declared, “international relations needs the rights of individuals to be upheld against the rights of states, or the result is despotism and impunity.” 

An organizing principle for this effort, Miliband said, is the concept of “countervailing power,” coined by the economist John Kenneth Galbraith several decades ago to describe efforts to reduce the concentration of economic power among an elite few.

“The idea of countervailing power has relevance in curbing the abuse of state power, not just private power,” Miliband said. “And it needs to apply in the international domain, not just the national one.”

As Miliband described it, efforts to create such countervailing power must take many forms. He approved of a potential international meeting, led by U.S. President Joe Biden, of democratic countries, to discuss ways of sustaining democracy. But Miliband described several other tools that could be used to curb right abuses.

These include U.N.-led investigations of war crimes; the use of democratic legal systems to pursue war crimes cases where applicable (such as a case of Syrians being prosecuted in Germany); economic sanctions; the suspension of aid programs in places where rights abuses occur; and even private-sector interventions such as boycotts, or the suspension of, say, insurance coverage for those violating humanitarian law.

“The drift to impunity will not be stopped without those with economic power taking a stand,” Miliband said.

None of this, Miliband emphasized, will be easy.

Referring to “The Narrow Corridor,” a book about the battle to sustain liberal democracy, by MIT economist Daron Acemoglu and University of Chicago political scientist James Robinson, Miliband noted that “there is nothing ‘natural’ about liberal democracy. If anything, it is an unnatural creation, and certainly one that takes perpetual nurture if it is to endure.”

Moreover, Miliband noted, when it comes to holding authoritarians accountable, “Accountability courts the accusation of being slow. But the methodical tortoise sometimes beats the hyperactive hare.”

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Nanostructured device stops light in its tracks

Understanding how light waves oscillate in time as they interact with materials is essential to understanding light-driven energy transfer in materials, such as solar cells or plants. Due to the fantastically high speeds at which light waves oscillate, however, scientists have yet to develop a compact device with enough time resolution to directly capture them.

Now, a team led by MIT researchers has demonstrated chip-scale devices that can directly trace the weak electric field of light waves as they change in time. Their device, which incorporates a microchip that uses short laser pulses and nanoscale antennas, is easy to use, requiring no special environment for operation, minimal laser parameters, and conventional laboratory electronics.

The team’s work, published earlier this month in Nature Photonics, may enable the development of new tools for optical measurements with applications in areas such as biology, medicine, food safety, gas sensing, and drug discovery.

“The potential applications of this technology are many,” says co-author Phillip Donnie Keathley, group leader and Research Laboratory of Electronics (RLE) research scientist. “For instance, using these optical sampling devices, researchers will be able to better understand optical absorption pathways in plants and photovoltaics, or to better identify molecular signatures in complex biological systems.”

Keathley’s co-authors are lead author Mina Bionta, a senior postdoc at RLE; Felix Ritzkowsky, a graduate student at the Deutsches Elektronen-Synchrotron (DESY) and the University of Hamburg who was an MIT visiting student; and Marco Turchetti, a graduate student in RLE. The team was led by Keathley working with professors Karl Berggren in the MIT Department of Electrical Engineering and Computer Science (EECS); Franz Kärtner of DESY and University of Hamburg in Germany; and William Putnam of the University of California at Davis. Other co-authors are Yujia Yang, a former MIT postdoc now at École Polytechnique Fédérale de Lausanne (EFPL), and Dario Cattozzo Mor, a former visiting student.

The ultrafast meets the ultrasmall — time stands still at the head of a pin

Researchers have long sought methods for measuring systems as they change in time. Tracking gigahertz waves, like those used for your phone or Wi-Fi router, requires a time resolution of less than 1 nanosecond (one-billionth of a second). To track visible light waves requires an even faster time resolution — less than 1 femtosecond (one-millionth of one-billionth of a second).

The MIT and DESY research teams designed a microchip that uses short laser pulses to create extremely fast electronic flashes at the tips of nanoscale antennas. The nanoscale antennas are designed to enhance the field of the short laser pulse to the point that they are strong enough to rip electrons out of the antenna, creating an electronic flash that is quickly deposited into a collecting electrode. These electronic flashes are extremely brief, lasting only a few hundred attoseconds (a few one-hundred-billionths of one-billionth of 1 second).

Using these fast flashes, the researchers were able to take snapshots of much weaker light waves oscillating as they passed by the chip.

“This work shows, once more, how the merger of nanofabrication and ultrafast physics can lead to exciting insights and new ultrafast measurements tools,” says Professor Peter Hommelhoff, chair for laser physics at the University of Erlangen-Nuremberg, who was not connected with this work. “All this is based on the deep understanding of the underlying physics. Based on this research, we can now measure ultrafast field waveforms of very weak laser pulses.”

The ability to directly measure light waves in time will benefit both science and industry, say the researchers. As light interacts with materials, its waves are altered in time, leaving signatures of the molecules inside. This optical field sampling technique promises to capture these signatures with greater fidelity and sensitivity than prior methods while using compact and integratable technology needed for real-world applications.

This research was supported by the U.S. Air Force Office of Scientific Research through a Young Investigator Program entitled “On-Chip PHz Processing of Optical Fields using Nanostructured Electron Emitters,” and a Multi University Research Initiative (MURI) program entitled “Empty State Electronics.” The work was also supported in part by the European Research Council, the MIT-Hamburg PIER program at DESY, and SENSE.nano at MIT.

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On course to create a fusion power plant

“There is no lone genius who solves all the problems.”

Dennis Whyte, director of the Plasma Science and Fusion Center (PSFC), is reflecting on a guiding belief behind his nuclear science and engineering class 22.63 (Principles of Fusion Engineering). He has recently watched his students, working in teams, make their final presentations on how to use fusion technology to create carbon-free fuel for shipping vessels. Since taking on the course over a decade ago, Whyte has moved away from standard lectures, prodding the class to work collectively on finding solutions to “real-world” issues. Over the past years the course, and its collaborative approach to design, has been instrumental in guiding the real future of fusion at the PSFC.

For decades researchers have explored fusion, the reaction that powers the sun, as a potential source of virtually endless, carbon-free energy on Earth. MIT has studied the process with a series of “Alcator” tokamaks, compact machines that use high magnetic fields to keep the hot plasma inside and away from the walls of a donut-shaped vacuum vessel long enough for fusion to occur. But understanding how plasma affects tokamak materials, and making the plasma dense and hot enough to sustain fusion reactions, has been elusive.

Incubating fusion machines and design teams

The second time he taught the course, Whyte was ready for his students to attack problems related to net-energy tokamak operation, necessary to produce substantial and economical power. These problems could not be explored with the PSFC’s Alcator C-Mod tokamak, which maintained fusion in only brief pulses, but they could be studied by a class tasked with designing a fusion device that can operate around the clock.

Around this time Whyte learned of high-temperature superconducting (HTS) tape, a newly available class of superconducting material that supported creating higher magnetic fields for effectively confining the plasma. It had the potential to surpass the performance of the previous generation of superconductors, like niobium-tin, which was being used in ITER, the burning plasma fusion experiment being built in France. Could the class design a machine that would answer questions about steady-state operation, while taking advantage of this revolutionary product? Furthermore, what if components of the machine could be easily taken out and replaced or altered, making the tokamak flexible for different experiments?

What the class conceived was a tokamak called “Vulcan.” Whyte calls his students’ efforts “eye-opening,” original enough to produce five peer-reviewed articles for Fusion Engineering and Design. Although the tokamak design was never directly built, its exploration of demountable magnetic coils, made from the new HTS tape, suggested a path for a fusion future.

Two years later, Whyte started his students down that path. He asked, “What would happen in a device where we try to make 500 megawatts of fusion power — identical to what ITER does — but we use this new HTS technology?”

With student teams working on separate aspects of the project and coordinating with other groups to create an integrated design, Whyte decided to make the class environment even more collaborative. He invited PSFC fusion experts to contribute. In this “collective community teaching” environment the students expanded on the research from the previous class, creating the basis for HTS magnets and demountable coils.

As before, the innovations explored resulted in a published paper. The lead author was then-graduate student Brandon Sorbom PhD ’17. He introduced the fusion community to ARC, describe in the article’s title as “a compact, high-field, fusion nuclear science facility and demonstration power plant with demountable magnets.” Because ARC was too large a project to consider building immediately, Whyte and some of his postdocs and students eventually began thinking about how they could study the most important elements of the ARC design in a smaller device.

Their answer was SPARC, based on the experience gained from designing Vulcan and ARC. This compact, high-field, net fusion energy experiment has become a collaboration between MIT and Commonwealth Fusion Systems (CFS), a Cambridge, Massachusetts-based startup seeded with talent from 22.63. Bob Mumgaard and Dan Brunner, who helped design Vulcan, are in CFS leadership, as is Brandon Sorbom. MIT NSE Assistant Professor Zach Hartwig, who participated as a student in the Vulcan project, has also stayed involved in the SPARC project and developments. 

The economic question

The course had become an incubator for researchers interested in using the latest technology to re-imagine how quickly a fusion power plant would be possible. It helped redirect the focus of the PSFC from Alcator C-Mod, which ended operation in 2016, toward SPARC and ARC, and technology innovation. In the process the PSFC, whose fusion program had been largely funded by the U.S. Department of Energy, realized it would also need to expand its research sponsorship to private funding.

The discussions with the private sector brought home the requirement not just for technical feasibility, but for making fusion an attractive product economically. This inspired Whyte to add an economic constraint to the 2020 22.63 class project, noting “it changes how you think about attacking the design.” Consequently, he expanded the teaching team to include Eric Ingersoll, founder and managing director at LucidCatalyst and TerraPraxis. Together they imagined a novel application and market that could use fusion as an intense carbon-free energy source — international shipping.

The virtual nature of this year’s course offered the unique chance for a number of students, postdocs, and teachers from Princeton University to join the class as volunteers, with the intent of eventually creating a similarly structured course at Princeton. They integrated with MIT students and instructors into four teams working interdependently to design an onboard method of generating ammonia fuel for ship engines. The device was dubbed “ARCH,” the H standing for Hydrogen. By making innovations to the fusion design, mostly focused on improving materials and heat removal, the team showed they could meet economic targets.

For MIT graduate student Rachel Bielajew, part of the Systems Integration Team, focusing on the economics of the project provided a very different experience from her other classes and everyday research.

“It was definitely motivating to have an economic target driving design choices,” she says. “The class also reinforced for me that the pathway to successful fusion reactors is multidisciplinary and there is important research to be done in many fields.”

Whyte’s teaching journey has been as transformative for him as for his students.

“If you give young people the time, the tools, and the imaginative space to work together towards meaningful goals — it’s hard to imagine a more powerful force,” he says. “The class and the innovation provided by the collective student effort have changed my worldview, and, I believe, the prospects for fusion energy.”

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China’s transition to electric vehicles

In recent decades, China’s rapid economic growth has enabled more and more consumers to buy their own cars. The result has been improved mobility and the largest automotive market in the world — but also serious urban air pollution, high greenhouse gas emissions, and growing dependence on oil imports.

To counteract those troubling trends, the Chinese government has imposed policies to encourage the adoption of plug-in electric vehicles (EVs). Since buying an EV costs more than buying a conventional internal combustion engine (ICE) vehicle, in 2009 the government began to provide generous subsidies for EV purchases. But the price differential and the number of buyers were both large, so paying for the subsidies became extremely costly for the government.

As a result, China’s policymakers planned to phase out the subsidies at the end of 2020 and instead impose a mandate on car manufacturers. Simply stated, the mandate requires that a certain percent of all vehicles sold by a manufacturer each year must be battery-powered. To avoid financial penalties, every year manufacturers must earn a stipulated number of points, which are awarded for each EV produced based on a complex formula that takes into account range, energy efficiency, performance, and more. The requirements get tougher over time, with a goal of having EVs make up 40 percent of all car sales by 2030.

This move will have a huge impact on the worldwide manufacture of EVs, according to William H. Green, the Hoyt C. Hottel Professor in Chemical Engineering. “This is one of the strongest mandates for electric cars worldwide, and it’s being imposed on the largest car market in the world,” he says. “There will be a gigantic increase in the manufacture of EVs and in the production of batteries for them, driving down the cost of both globally.”

But what will be the impact of the mandate within China? The transition to EVs will bring many environmental and other benefits. But how much will it cost the nation? In 2016, MIT chemical engineering colleagues Green and then-graduate student I-Yun Lisa Hsieh PhD ’20 decided to find out. Their goal was to examine the mixed impacts of the mandate on all affected factors: battery prices, manufacturing costs, vehicle prices and sales, and the cost to the consumer of owning and operating a car. Based on their results, they could estimate the total societal cost of complying with the mandate in the coming decade. (Note that the Chinese government recently extended subsidy support for EVs for two years due to the Covid-19 pandemic and that this analysis was performed before that change was announced.)

Looking at battery prices

“The main reason why EVs are costly is that their batteries are expensive,” says Green. In recent years, battery prices have dropped rapidly, largely due to the “learning effect”: As production volumes increase, manufacturers find ways to improve efficiency, and costs go down. It’s generally assumed that battery prices will continue to decrease as EVs take over more of the car market.

Using a new modeling approach, Green and Hsieh determined that learning effects will lower costs appreciably for battery production, but not much for the mining and synthesis of critical battery materials. They concluded that the price of the most widely used EV battery technology — the lithium-ion nickel-manganese-cobalt battery — will indeed drop as more are manufactured. But the decline will slow as the price gets closer to the cost of the raw materials in it.

Using the resulting estimates of battery price, the researchers calculated the extra cost of manufacturing an EV over time and — assuming a standard markup for profit — determined the likely selling price for those cars. In previous work, they had used a variety of data sources and analytical techniques to determine “affordability” for the Chinese population — in other words, the fraction of their income available to spend on buying a car. Based on those findings, they examined the expected impact on car sales in China between 2018 and 2030.

As a baseline for comparison, the researchers first assumed a “counterfactual” (not true-to-life) scenario — car sales without significant adoption of EVs, so without the new mandate. Under that assumption, annual projected car sales climb to more than 34 million by 2030.

When the subsidy on EV purchases is eliminated and the mandate is enacted in 2020, total car sales shrink. But thereafter, the growing economy and rising incomes increase consumer purchasing power and drive up the demand for private car ownership. Annual sales are on average 20 percent lower than in the counterfactual scenario, but they’re projected to reach about 30 million by 2030.

The researchers also projected the breakdown in sales between ICE vehicles and battery EVs at three points in time. According to that analysis, in 2020, EVs make up just 7 percent of the total (1.6 million vehicles). By 2025, that share is up to 21 percent (5.4 million). And by 2030, it’s up to 37 percent (11.2 million) — close to the government’s 40 percent target. Altogether, 66 million EVs are sold between 2020 and 2030.

Those results also track the split between two types of plug-in EVs: pure battery EVs and hybrid EVs (which are powered by both batteries and gasoline). About twice as many pure battery EVs are sold than hybrid EVs, even though the former are more expensive due to the higher cost of their batteries. “The mandate includes a special preference for cars with a longer range, which means cars with large batteries,” says Green. “So carmakers have a big incentive to manufacture the pure battery EVs and be awarded extra points under the mandate formula.”

For the consumer, the added cost of owning an EV includes any difference in vehicle expenses over the whole lifetime of the car. To calculate that difference, the researchers quantified the “total cost of ownership,” or TCO, including the purchase cost, fuel cost, and operating and maintenance costs (including insurance) of their two plug-in EVs and an ICE vehicle out to 2030.

Their results show that before 2020, owning either type of plug-in EV is less costly than owning an ICE vehicle due to the subsidy paid on EV purchases. After the subsidy is removed and the mandate imposed in 2020, owning a hybrid EV is comparable to owning an ICE vehicle. Owning a pure battery EV is more expensive due to its high-cost batteries. Dropping battery prices reduces total ownership cost for both types of EVs, but the pure battery EV remains more expensive out to 2030.

Cost to society

The next step for the researchers was to calculate the total cost to China of forcing the adoption of EVs. The basic approach is straightforward: They take the extra TCO for each EV sold in each year, discount that cost to its present value, and multiply the resulting figure by the number of cars sold in that year. (They exclude taxes embedded in the purchase prices of the vehicle, of electricity and gasoline, and so on, as the society will have to pay other taxes to replace that lost revenue.)

Using that methodology, they calculated the incremental cost to society of each EV sold in each year as well as the extra cost per kilometer driven, assuming that the vehicle has a lifetime of 12 years and is driven 12,500 kilometers each year. The results show that the incremental cost of owning and driving an EV decreases from 2021 to 2030. The cost declines more for pure battery EVs than for hybrid EVs, but the former remain more costly.

By combining the per-car cost to society with the number of cars sold, the researchers calculated the total extra cost incurred. In their results, the total number of EVs sold in a year more than offsets any decrease in per-vehicle cost, so the incremental cost to society grows. And that cost is sizeable. On average, the transition to EVs forced by the mandate will cost 100 billion yuan per year from 2021 to 2030, which is about 2 percent of the nationwide expenditure in the transport sector every year.

During the 10 years from 2021-30, the annual societal cost of the transition to almost 40 percent EVs is equivalent to about 0.1 percent of China’s growing gross domestic product. “So the cost to society of forcing the sale of EVs in place of ICE vehicles is significant,” says Hsieh. “People will have far less money in their pockets to spend on other purchases.”

Other considerations

Green and Hsieh stress that the high societal cost of the forced EV adoption must be considered in light of the potential benefits to be gained. For example, switching from ICE vehicles to EVs will lower air pollution and associated health costs; reduce carbon dioxide emissions to help mitigate climate change; and reduce reliance on imported petroleum, enhancing the country’s national energy security and balance of payments.

Hsieh is now working to quantify those benefits so that the team can perform a proper cost-benefit analysis of China’s transition to EVs. Her initial results suggest that the monetized benefits are — like the costs — substantial. “The benefits appear to be the same order of magnitude as the costs,” she says. “It’s so close that we need to be careful to get the numbers right.”

The researchers cite two other factors that may impact the cost side of the equation. In early 2018, six Chinese megacities with high air pollution began restricting the number of license plates issued for ICE vehicles and charging high fees for them. With their lower-cost, more-abundant “green car plates,” EVs became cost-competitive, and sales soared. To protect Chinese carmakers, the national government recently announced that it plans to end those restrictions. The outcome and its impacts on EV sales remain uncertain. (Again, due to the pandemic, policies restricting car ownership have mostly been relaxed for now.)

The second caveat concerns how carmakers price their vehicles. The results reported here assume that prices are calculated as they are today: the cost of manufacturing the vehicle plus a certain percentage markup for profit. With the new mandate in place, automakers will need to change their pricing strategy so as to persuade enough buyers to purchase EVs to reach the required fraction. “We don’t know what they’re going to do, but one possibility is that they’ll lower the price of their battery cars and raise the price of their gasoline cars,” says Green. “That way, they can still make their profits while operating within the law.” As an example, he cites how U.S. carmakers responded to Corporate Average Fuel Economy standards by adjusting the relative prices of their low- and high-efficiency vehicles.

While such a change in Chinese automakers’ pricing strategy would lower the price of EVs, it would also push up average car prices overall, because the total car sales mix is dominated by ICE vehicles. “Some people in China who would otherwise be able to afford a cheap gasoline car now won’t be able to afford it,” says Hsieh. “They’ll be priced out of the market.”

Green emphasizes the impact of the mandate on all carmakers worldwide. “I can’t overstate how hugely important this is,” he says. “As soon as the mandate came out, carmakers realized that electric vehicles had become a major market rather than a niche market on the side.” And he believes that even without subsidies, the added expense of buying an EV won’t be prohibitive for many car buyers — especially in light of the benefits they offer.

However, he does have a final concern. As more and more EVs are manufactured, global supplies of critical battery materials will become increasingly limited. At the same time, however, the supply of spent batteries will increase, creating an opportunity to recycle critical materials for use in new batteries and simultaneously prevent environmental threats from their disposal. The researchers recommend that policymakers “help to integrate the entire industry chain among automakers, battery producers, used-car dealers, and scrap companies in battery recycling systems to achieve a more sustainable society.”

This research was supported through the MIT Energy Initiative’s Mobility of the Future study.

This article appears in the Autumn 2020 issue of Energy Futures, the magazine of the MIT Energy Initiative.

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Q&A: Vivienne Sze on crossing the hardware-software divide for efficient artificial intelligence

Not so long ago, watching a movie on a smartphone seemed impossible. Vivienne Sze was a graduate student at MIT at the time, in the mid 2000s, and she was drawn to the challenge of compressing video to keep image quality high without draining the phone’s battery. The solution she hit upon called for co-designing energy-efficient circuits with energy-efficient algorithms.

Sze would go on to be part of the team that won an Engineering Emmy Award for developing the video compression standards still in use today. Now an associate professor in MIT’s Department of Electrical Engineering and Computer Science, Sze has set her sights on a new milestone: bringing artificial intelligence applications to smartphones and tiny robots.

Her research focuses on designing more-efficient deep neural networks to process video, and more-efficient hardware to run those applications. She recently co-published a book on the topic, and will teach a professional education course on how to design efficient deep learning systems in June.

On April 29, Sze will join Assistant Professor Song Han for an MIT Quest AI Roundtable on the co-design of efficient hardware and software moderated by Aude Oliva, director of MIT Quest Corporate and the MIT director of the MIT-IBM Watson AI Lab. Here, Sze discusses her recent work.

Q: Why do we need low-power AI now?

A: AI applications are moving to smartphones, tiny robots, and internet-connected appliances and other devices with limited power and processing capabilities. The challenge is that AI has high computing requirements. Analyzing sensor and camera data from a self-driving car can consume about 2,500 watts, but the computing budget of a smartphone is just about a single watt. Closing this gap requires rethinking the entire stack, a trend that will define the next decade of AI.

Q: What’s the big deal about running AI on a smartphone?

A: It means that the data processing no longer has to take place in the “cloud,” on racks of warehouse servers. Untethering compute from the cloud allows us to broaden AI’s reach. It gives people in developing countries with limited communication infrastructure access to AI. It also speeds up response time by reducing the lag caused by communicating with distant servers. This is crucial for interactive applications like autonomous navigation and augmented reality, which need to respond instantaneously to changing conditions. Processing data on the device can also protect medical and other sensitive records. Data can be processed right where they’re collected.

Q: What makes modern AI so inefficient?

A: The cornerstone of modern AI — deep neural networks — can require hundreds of millions to billions of calculations — orders of magnitude greater than compressing video on a smartphone. But it’s not just number crunching that makes deep networks energy-intensive — it’s the cost of shuffling data to and from memory to perform these computations. The farther the data have to travel, and the more data there are, the greater the bottleneck.

Q: How are you redesigning AI hardware for greater energy efficiency?

A: We focus on reducing data movement and the amount of data needed for computation. In some deep networks, the same data are used multiple times for different computations. We design specialized hardware to reuse data locally rather than send them off-chip. Storing reused data on-chip makes the process extremely energy-efficient.  

We also optimize the order in which data are processed to maximize their reuse. That’s the key property of the Eyeriss chip that was developed in collaboration with Joel Emer. In our followup work, Eyeriss v2, we made the chip flexible enough to reuse data across a wider range of deep networks. The Eyeriss chip also uses compression to reduce data movement, a common tactic among AI chips. The low-power Navion chip that was developed in collaboration with Sertac Karaman for mapping and navigation applications in robotics uses two to three orders of magnitude less energy than a CPU, in part by using optimizations that reduce the amount of data processed and stored on-chip. 

Q: What changes have you made on the software side to boost efficiency?

A: The more that software aligns with hardware-related performance metrics like energy efficiency, the better we can do. Pruning, for example, is a popular way to remove weights from a deep network to reduce computation costs. But rather than remove weights based on their magnitude, our work on energy-aware pruning suggests you can remove the more energy-intensive weights to improve overall energy consumption. Another method we’ve developed, NetAdapt, automates the process of adapting and optimizing a deep network for a smartphone or other hardware platforms. Our recent followup work, NetAdaptv2, accelerates the optimization process to further boost efficiency.

Q: What low-power AI applications are you working on?

A: I’m exploring autonomous navigation for low-energy robots with Sertac Karaman. I’m also working with Thomas Heldt to develop a low-cost and potentially more effective way of diagnosing and monitoring people with neurodegenerative disorders like Alzheimer’s and Parkinson’s by tracking their eye movements. Eye-movement properties like reaction time could potentially serve as biomarkers for brain function. In the past, eye-movement tracking took place in clinics because of the expensive equipment required. We’ve shown that an ordinary smartphone camera can take measurements from a patient’s home, making data collection easier and less costly. This could help to monitor disease progression and track improvements in clinical drug trials.

Q: Where is low-power AI headed next?

A: Reducing AI’s energy requirements will extend AI to a wider range of embedded devices, extending its reach into tiny robots, smart homes, and medical devices. A key challenge is that efficiency often requires a tradeoff in performance. For wide adoption, it will be important to dig deeper into these different applications to establish the right balance between efficiency and accuracy.

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Q&A: Vivienne Sze on crossing the hardwire-software divide for efficient artificial intelligence

Not so long ago, watching a movie on a smartphone seemed impossible. Vivienne Sze was a graduate student at MIT at the time, in the mid 2000s, and she was drawn to the challenge of compressing video to keep image quality high without draining the phone’s battery. The solution she hit upon called for co-designing energy-efficient circuits with energy-efficient algorithms.

Sze would go on to be part of the team that won an Engineering Emmy Award for developing the video compression standards still in use today. Now an associate professor in MIT’s Department of Electrical Engineering and Computer Science, Sze has set her sights on a new milestone: bringing artificial intelligence applications to smartphones and tiny robots.

Her research focuses on designing more-efficient deep neural networks to process video, and more-efficient hardware to run those applications. She recently co-published a book on the topic, and will teach a professional education course on how to design efficient deep learning systems in June.

On April 29, Sze will join Assistant Professor Song Han for an MIT Quest AI Roundtable on the co-design of efficient hardware and software moderated by Aude Oliva, director of MIT Quest Corporate and the MIT director of the MIT-IBM Watson AI Lab. Here, Sze discusses her recent work.

Q: Why do we need low-power AI now?

A: AI applications are moving to smartphones, tiny robots, and internet-connected appliances and other devices with limited power and processing capabilities. The challenge is that AI has high computing requirements. Analyzing sensor and camera data from a self-driving car consumes about 2,500 watts, but the computing budget of a smartphone is just about a single watt. Closing this gap requires rethinking the entire stack, a trend that will define the next decade of AI.

Q: What’s the big deal about running AI on a smartphone?

A: It means that the data processing no longer has to take place in the “cloud,” on racks of warehouse servers. Untethering compute from the cloud allows us to broaden AI’s reach. It gives people in developing countries with limited communication infrastructure access to AI. It also speeds up response time by reducing the lag caused by communicating with distant servers. This is crucial for interactive applications like autonomous navigation and augmented reality, which need to respond instantaneously to changing conditions. Processing data on the device can also protect medical and other sensitive records. Data can be processed right where they’re collected.

Q: What makes modern AI so inefficient?

A: The cornerstone of modern AI — deep neural networks — can require hundreds of millions to billions of calculations — orders of magnitude greater than compressing video on a smartphone. But it’s not just number crunching that makes deep networks energy-intensive — it’s the cost of shuffling data to and from memory to perform these computations. The farther the data have to travel, and the more data there are, the greater the bottleneck.

Q: How are you redesigning AI hardware for greater energy efficiency?

A: We focus on reducing data movement and the amount of data needed for computation. In some deep networks, the same data are used multiple times for different computations. We design specialized hardware to reuse data locally rather than send them off-chip. Storing reused data on-chip makes the process extremely energy-efficient.  

We also optimize the order in which data are processed to maximize their reuse. That’s the key property of the Eyeriss chip that I co-designed with Joel Emer. In our followup work, Eyeriss v2, we made the chip flexible enough to reuse data across a wider range of deep networks. The Eyeriss chip also uses compression to reduce data movement, a common tactic among AI chips. The low-power Navion chip that I co-designed with Sertac Karaman for mapping and navigation applications in robotics uses two to three orders of magnitude less energy than a CPU, in part by using optimizations that reduce the amount of data processed and stored on-chip. 

Q: What changes have you made on the software side to boost efficiency?

A: The more that software aligns with hardware-related performance metrics like energy efficiency, the better we can do. Pruning, for example, is a popular way to remove weights from a deep network to reduce computation costs. But rather than remove weights based on their magnitude, our work on energy-aware pruning suggests you can remove the more energy-intensive weights to improve overall energy consumption. Another method we’ve developed, NetAdapt, automates the process of adapting and optimizing a deep network for a smartphone or other hardware platforms. Our recent followup work, NetAdaptv2, accelerates the optimization process to further boost efficiency.

Q: What low-power AI applications are you working on?

A: I’m exploring autonomous navigation for low-energy robots with Sertac Karaman. I’m also working with Thomas Heldt to develop a low-cost and potentially more effective way of diagnosing and monitoring people with neurodegenerative disorders like Alzheimer’s and Parkinson’s by tracking their eye movements. Eye-movement properties like reaction time could potentially serve as biomarkers for brain function. In the past, eye-movement tracking took place in clinics because of the expensive equipment required. We’ve shown that an ordinary smartphone camera can take measurements from a patient’s home, making data collection easier and less costly. This could help to monitor disease progression and track improvements in clinical drug trials.

Q: Where is low-power AI headed next?

A: Reducing AI’s energy requirements will extend AI to a wider range of embedded devices, extending its reach into tiny robots, smart homes, and medical devices. A key challenge is that efficiency often requires a tradeoff in performance. For wide adoption, it will be important to dig deeper into these different applications to establish the right balance between efficiency and accuracy.

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Cave deposits show surprising shift in permafrost over the last 400,000 years

Nearly one quarter of the land in the Northern Hemisphere, amounting to some 9 million square miles, is layered with permafrost — soil, sediment, and rocks that are frozen solid for years at a time. Vast stretches of permafrost can be found in Alaska, Siberia, and the Canadian Arctic, where persistently freezing temperatures have kept carbon, in the form of decayed bits of plants and animals, locked in the ground.

Scientists estimate that more than 1,400 gigatons of carbon is trapped in the Earth’s permafrost. As global temperatures climb, and permafrost thaws, this frozen reservoir could potentially escape into the atmosphere as carbon dioxide and methane, significantly amplifying climate change. However, little is known about permafrost’s stability, today or in the past.

Now geologists at MIT, Boston College, and elsewhere have reconstructed permafrost’s history over the last 1.5 million years. The researchers analyzed cave deposits in locations across western Canada and found evidence that, between 1.5 million and 400,000 years ago, permafrost was prone to thawing, even in high Arctic latitudes. Since then, however, permafrost thaw has been limited to sub-Arctic regions.

The results, published today in Science Advances, suggest that the planet’s permafrost shifted to a more stable state in the last 400,000 years, and has been less susceptible to thawing since then. In this more stable state, permafrost likely has retained much of the carbon that it has built up during this time, having little opportunity to gradually release it.

“The stability of the last 400,000 years may actually work against us, in that it has allowed carbon to steadily accumulate in permafrost over this time. Melting now might lead to substantially greater releases of carbon to the atmosphere than in the past,” says study co-author David McGee, associate professor in MIT’s Department of Earth, Atmospheric, and Planetary Sciences.

McGee’s co-authors are Ben Hardt and Irit Tal at MIT; Nicole Biller-Celander, Jeremy Shakun, and Corinne Wong at Boston College; Alberto Reyes at the University of Alberta; Bernard Lauriol at the University of Ottawa; and Derek Ford at McMaster University.

Stacked warming

Periods of past warming are considered interglacial periods, or times between global ice ages. These geologically brief windows can warm permafrost enough to thaw. Signs of ancient permafrost thaw can be seen in stalagmites and other mineral deposits left behind as water moves through the ground and into caves. These caves, particularly at high Arctic latitudes, are often remote and difficult to access, and as a result, there has been little known about the history of permafrost, and its past stability in warming climates.

However, in 2013, researchers at Oxford University were able to sample cave deposits from a few locations across Siberia; their analysis suggested that permafrost thaw was widespread throughout Siberia prior to 400,000 years ago. Since then, the results showed a much-reduced range of permafrost thaw.

Shakun and Biller-Celander wondered whether the trend toward a more stable permafrost was a global one, and looked to carry out similar studies in Canada to reconstruct the permafrost history there. They linked up with pioneering cave scientists Lauriol and Ford, who provided samples of cave deposits that they collected over the years from three distinct permafrost regions: the southern Canadian Rockies, Nahanni National Park in the Northwest Territories, and the northern Yukon.

In total, the team obtained 74 samples of speleothems, or sections of stalagmites, stalactites, and flowstones, from at least five caves in each region, representing various cave depths, geometries, and glacial histories. Each sampled cave was located on exposed slopes that were likely the first parts of the permafrost landscape to thaw with warming.

The samples were flown to MIT, where McGee and his lab used precise geochronology techniques to determine the ages of each sample’s layers, each layer reflecting a period of permafrost thaw.

“Each speleothem was deposited over time like stacked traffic cones,” says McGee. “We started with the outermost, youngest layers to date the most recent time that the permafrost thawed.”

Arctic shift

McGee and his colleagues used techniques of uranium/thorium geochronology to date the layers of each speleothem. The dating technique relies on the natural decay process of uranium to its daughter isotope, thorium 230, and the fact that uranium is soluble in water, whereas thorium is not.

“In the rocks above the cave, as waters percolate through, they accumulate uranium and leave thorium behind,” McGee explains. “Once that water gets to the stalagmite surface and precipitates at time zero, you have uranium, and no thorium. Then gradually, uranium decays and produces thorium.”

The team drilled out small amounts from each sample and dissolved them through various chemical steps to isolate uranium and thorium. Then they ran the two elements through a mass spectrometer to measure their amounts, the ratio of which they used to calculate a given layer’s age.

From their analysis, the researchers observed that samples collected from the Yukon and the farthest northern sites bore samples no younger than 400,000 years old, suggesting permafrost thaw has not occurred in those sites since then.

“There may have been some shallow thaw, but in terms of the entire rock above the cave being thawed, that hasn’t occurred for the last 400,000 years, and was much more common prior to that,” McGee says.

The results suggest that the Earth’s permafrost was much less stable prior to 400,000 years ago and was more prone to thawing, even during interglacial periods when levels of temperature and atmospheric carbon dioxide were on par with modern levels, as other work has shown.

“To see this evidence of a much less stable Arctic prior to 400,000 years ago, suggests even under similar conditions, the Arctic can be a very different place,” McGee says. “It raises questions for me about what caused the Arctic to shift into this more stable condition, and what can cause it to shift out of it.”

This research was supported, in part, by the National Science Foundation, the National Sciences and Engineering Research Council of Canada, and the Polar Continental Shelf Program.

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How to get salt out of water: Make it self-eject

About a quarter of a percent of the entire gross domestic product of industrialized countries is estimated to be lost through a single technical issue: the fouling of heat exchanger surfaces by salts and other dissolved minerals. This fouling lowers the efficiency of multiple industrial processes and often requires expensive countermeasures such as water pretreatment. Now, findings from MIT could lead to a new way of reducing such fouling, and potentially even enable turning that deleterious process into a productive one that can yield saleable products.

The findings are the result of years of work by recent MIT graduates Samantha McBride PhD ’20 and Henri-Louis Girard PhD ’20 with professor of mechanical engineering Kripa Varanasi. The work, reported today in the journal Science Advances, shows that due to a combination of hydrophobic (water repelling) surfaces and heat, dissolved salts can crystallize in a way that makes it easy to remove them from the surface, in some cases by gravity alone.

When the researchers began studying the way salts crystallize on such surfaces, they found that the precipitating salt would initially form a partial spherical shell around a droplet. Unexpectedly, this shell would then suddenly rise on a set of spindly leg-like extensions grown during evaporation. The process repeatedly produced  multilegged shapes, resembling elephants and other animals, and even sci-fi droids. The researchers dubbed these formations “crystal critters” in the title of their paper.

After many experiments and detailed analysis, the team determined the mechanism that was producing these leg-like protrusions. They also showed how the protrusions varied depending on temperature and the nature of the hydrophobic surface, which was produced by creating a nanoscale pattern of low ridges. They found that the narrow legs holding up these critter-like forms continue to grow upward from the bottom, as the salty water flows downward through the straw-like legs and precipitates out at the bottom, somewhat like a growing icicle, only balanced on its tip. Eventually the legs become so long they are unable to support the critter’s weight, and the blob of salt crystal breaks off and falls or is swept away.

The work was motivated by the desire to limit or prevent the formation of scaling on surfaces, including inside pipes where such scaling can lead to blockages, Varanasi says. “Samantha’s experiment showed this interesting effect where the scale pretty much just pops off by itself,” he says.

“These legs are hollow tubes, and the liquid is funneled down through these tubes. Once it hits the bottom and evaporates, it forms new crystals that continuously increase the length of the tube,” McBride says. “In the end, you have very, very limited contact between the substrate and the crystal, to the point where these are going to just roll away on their own.”

McBride recalls that in doing the initial experiments as part of her doctoral thesis work, “we definitely suspected that this particular surface would work well for eliminating sodium chloride adhesion, but we didn't know that a consequence of preventing that adhesion would be the ejection of the entire thing” from the surface.

One key, she found, was the exact scale of the patterns on the surface. While many different length scales of patterning can yield hydrophobic surfaces, only patterns at the nanometer scale achieve this self-ejecting effect. “When you evaporate a drop of salt water on a superhydrophobic surface, usually what happens is those crystals start getting inside of the texture and just form a globe, and they don't end up lifting off,” McBride says. “So it's something very specific about the texture and the length scale that we're looking at here that allows this effect to occur.”

This self-ejecting process, based simply on evaporation from a surface whose texture can be easily produced by etching, abrasion, or coating, could be a boon for a wide variety of processes. All kinds of metal structures in a marine environment or exposed to seawater suffer from scaling and corrosion. The findings may also enable new methods for investigating the mechanisms of scaling and corrosion, the researchers say.

By varying the amount of heat along the surface, it’s even possible to get the crystal formations to roll along in a specific direction, the researchers found. The higher the temperature, the faster the growth and liftoff of these forms takes place, minimizing the amount of time the crystals block the surface.

Heat exchangers are used in a wide variety of different processes, and their efficiency is strongly affected by any surface fouling. Those losses alone, Varanasi says, equal a quarter of a percent of the GDP of the U.S. and other industrialized nations. But fouling is also a major factor in many other areas. It affects pipes in water distribution systems, geothermal wells, agricultural settings, desalination plants, and a variety of renewable energy systems and carbon dioxide conversion methods.

This method, Varanasi says, might even enable the use of untreated salty water in some processes where that would not be practical otherwise, such as in some industrial cooling systems. Further, in some situations the recovered salts and other minerals could be salable products.

While the initial experiments were done with ordinary sodium chloride, other kinds of salts or minerals are expected to produce similar effects, and the researchers are continuing to explore the extension of this process to other kinds of solutions.

Because the methods for making the textures to produce a hydrophobic surface are already well-developed, Varanasi says, implementing this process at large industrial scale should be relatively rapid, and could enable the use of salty or brackish water for cooling systems that would otherwise require the use of valuable and often limited fresh water. For example, in the U.S. alone, a trillion gallons of fresh water are used per year for cooling. A typical 600-megawatt power plant consumes about a billion gallons of water per year, which could be enough to serve 100,000 people. That means that using sea water for cooling where possible could help to alleviate a fresh-water scarcity problem.

“This work shows a remarkable and interesting phenomenon,” says Neelesh Patankar, a professor of mechanical engineering at Northwestern University, who was not associated with this research. The findings, he says, “may lead to an entirely new approach to mitigate mineral fouling in industrial processes. Not only is this work interesting from a fundamental science perspective, in my opinion it is also of practical importance.”

The work was supported by Equinor through MIT Energy Initiative, the MIT Martin Fellowship Program, and the National Science Foundation.

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Investigating the embattled brain

A car backfires in a parking lot. An army veteran, recently returned from a combat zone, might duck and cover. He knows that he is no longer in an active war zone, but he was trained to react before thinking, an ability that meant life over death at one point in his life.

That training is so ingrained it has physically altered the way his brain works, weakening the connection between the amygdala, which is responsible for emotions like fear, and the prefrontal cortex, which regulates or controls these emotional responses.

How post-traumatic stress disorder (PTSD) — a mental condition caused by a severe psychological shock that leaves persistent symptoms such as anxiety, depression, sleep disturbance, and even physical pain — affects the brain and its functions is the focus of graduate student Omar Rutledge’s research in the Department of Brain and Cognitive Sciences. He is uniquely situated to study this topic, having been deployed to Iraq himself from March 2003 to July 2004, resulting in firsthand experience with PTSD.

Coronavirus impedes and inspires

Rutledge, a third-year PhD candidate, is looking at ways to specifically prevent situations in which acting on a triggering event before thinking is no longer a useful survival skill. For example, when our brains sense fear, they send signals that may temporarily alter our skin to conduct electricity more easily — think of the infamous polygraph, or lie-detector, test. In the future, a device like a watch could measure this “skin conductance” and send an alert allowing the wearer to prioritize managing their response to the triggering event, such as breathing more slowly instead of ducking behind an object, effectively retraining the brain to be less responsive to triggering events.

Though Covid-19 has put some aspects of this research on hold, the pandemic has inspired another project based on the need for social distancing. Rutledge wants to test whether the loneliness caused by physical distancing protocols can induce physical or chemical changes in the brain similar to changes affiliated with PTSD.

Imagine walking down the street at night. Someone else approaches from the other direction. If someone is accompanying you, that new person is likely not evaluated as a threat. When you are by yourself? “Most likely,” he asserts. The longer humans are alone, the more other people become perceived as threats.

“There’s this hypervigilance that occurs in loneliness, and there’s also something very similar that occurs in PTSD — a heightened awareness of potential threats. The combination of the two may lead to more adverse reactions in people with PTSD,” says Rutledge, who is the 2020-21 recipient of McGovern Institute for Brain Research’s Michael Ferrara graduate fellowship provided by the Poitras Center for Psychiatric Disorders Research.

Work has already been done at MIT to investigate short-term loneliness’ effect on the brain on a social level. In his future research plans, Rutledge said he hopes to explore whether and how chronic loneliness causes cognitive impairment. From there, further investigation could determine if loneliness has a deeper impact on veterans who have PTSD.

From war zone to campus

After making the seemingly impossible transition back from Iraq into civilian life in the States, Rutledge turned to psychology to learn more about what he was experiencing, earning a bachelor’s degree in psychology from the University of Alaska at Fairbanks in 2012. To his dismay, he found little had been done to truly understand the nature of combat-associated PTSD.  

For a broken bone, a doctor diagnoses the problem via X-ray, develops a plan to correct the issue, employs the necessary steps for repair, and then evaluates if the treatment succeeded. There is no analogous process for mental disorders.

“We can’t scan your individual brain and come up with a list of things that we can do to improve your situation. There’s nothing like that,” Rutledge says. “But that doesn’t mean we can’t try. That’s something that’s been on my mind since the very beginning.” He went on to earn a master’s degree in biomedical imaging at the University of California at San Francisco, which he completed in 2015.

For his next step, he planned to pursue a doctorate in a neuroscience program in order to go beyond understanding what is physically happening in the brain and begin to tie the brain to the mind using various tools.

But he never imagined being able to do this work at MIT.

A new kind of mission

Rutledge’s firsthand combat experience has enabled prior studies into PTSD with veterans to go deeper despite dredging up painful memories. “Even though I may be reopening my own wounds by listening to others share their stories, if I can help other veterans heal, I feel it’s worth it. In the process, it makes me a little bit stronger as well,” he says.

Last year, Rutledge received a James S. (1972) and Muguette Alder Fellowship, which is awarded annually to a graduate student in brain and cognitive sciences working on bipolar disorder and related diseases or, more broadly, mental illness, and is sponsored by a gift from Jim and Muguette Alder.

With Rutledge now a part of the “Gab Lab,” John Gabrieli, the Grover Hermann Professor of Health Sciences and Technology, cognitive neuroscience professor in the Department of Brain and Cognitive Sciences, and member of McGovern Institute, has someone who can advocate for PTSD research at MIT.

“I feel like it has been a mission of mine to do this kind of work,” explains Rutledge. “In the world of PTSD research, I look to my left and to my right, and I don’t see other veterans, certainly not a former infantry guy. If there are so few of us in this space, I feel like I have an obligation to make a difference for all who suffer from the traumatic experiences of war.”

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Up for a challenge in the lab and on the mat

At 5:30 a.m., his alarm would start blaring. Reluctant to get up, Jose Aceves-Salvador would hear his parents outside his door, bustling to get ready for work. “Ponte las pilas!” they would shout, using a Spanish idiom expressing encouragement to work hard.

The expression would stick with Aceves-Salvador throughout high school as he dreamed of going to college. Although neither of his parents had college degrees, they were both huge supporters of his decision. As Mexican immigrants who had moved to Los Angeles in their youth, their goal was to see their son achieve a better future.

“They didn’t know much about applying to college, but they knew that when you go, you’re set up for life,” explains Aceves-Salvador. “Whenever I’d hit a low, I’d think of how they’d tell me to work hard and keep going.”

To get a first taste of campus life, Aceves-Salvador attended a program at MIT called Minority Introduction to Engineering and Science (MITES) during the summer before his junior year of high school. MITES allowed Aceves-Salvador to take a genomics class at the Broad Institute of MIT and Harvard. The experience exposed him to the exciting and ever-changing world of scientific research.

“After MITES was over, I knew I wanted to go back to MIT. There was so much I still wanted to learn and explore,” Aceves-Salvador says. “In my mind, MIT was a huge reach school. But I couldn’t let go of the goal and figured I’d apply anyway.”

Aceves-Salvador was admitted and is now a senior studying biology with a concentration in education. “I love the learning process, and in biology there’s a never-ending cycle of questions to explore,” he says enthusiastically. “There are also so many opportunities to learn from failures and successes along the way.”

Aceves-Salvador wanted to do research the moment he arrived on campus, but struggled to get a lab position without any prior experience. Fortunately, in his sophomore year an interview with Xun Gong, a postdoc with the Strano Research Group, led to an opportunity. The lab had recently observed a new phenomenon in single-walled carbon nanotubes and wanted to investigate further. Aceves-Salvador joined the group and led the side project with Gong’s mentorship. “The project, and the fact that we were going into the unknown and exploring a new phenomenon perfectly fit my mentality, so I immediately said yes,” says Aceves-Salvador. “I eventually got my first taste of real science and have been hooked ever since.” 

Since his first project, Aceves-Salvador has continued to do research, in multiple MIT labs and at the University of California at Los Angeles one summer. He has enjoyed working on everything from modeling protein behavior to developing a gut microphysical system. “As a college student, you come in barely knowing what’s out there to explore. I’ve tried to use my undergraduate degree to learn more about biology as a field before committing to something,” he says.

Across his different lab experiences, Aceves-Salvador has noted the lack of Latinx representation in science. He is devoted to encouraging greater minority representation in STEM and has served as a teaching assistant and mentor for MITES and the MIT Leadership Training Institute. These roles have allowed him to share his empowering story and love for education by teaching others. “I really wouldn’t be here if it weren’t for programs like MITES. I’m so grateful I can give back and be part of its legacy,” Aceves-Salvador says.

For an afterschool program he led in Los Angeles, Aceves-Salvador shaped the science curriculum he teaches to be more exciting to young learners. Students were challenged through hands-on activities, like creating chemical reactions, to make their own observations. “At a young age you’re so curious and curiosity is what science is all about,” says Aceves-Salvador. “But oftentimes, this curiosity gets stifled through outside pressures. In the hands-on activities I help lead, I try to create an open environment that encourages students to feel comfortable asking questions.”

Aceves-Salvador noticed the same approaches being used abroad during his international teaching experiences. Through MISTI Global Teaching Labs, he has traveled to Spain and Mexico to teach biology, math, health sciences, and chemistry. In Spain, Aceves-Salvador got to lead a discussion with local teachers on how to approach and encourage STEM education. “At least in the school I was placed in, I saw greater opportunities for students to explore different corners of science in their projects,” he notes. “The community-centric classrooms were also more focused on discussion among the students and less lecture.”

Outside of teaching and research, Aceves-Salvador enjoys channeling his passionate energy into dance and cheer. He has been part of MIT Cheerleading and DanceTroupe. These activities have pushed him physically, for example training him to lift cheerleaders on his shoulders and throw them into the air. He credits the intense nature of workout routines for creating a deep communal bond between members. “You share a connection with people after they’ve seen you fall on your face,” he jokes. “You can’t really hide anything at that point.”

This fall, Aceves-Salvador will be attending Harvard Medical School to pursue a PhD through the Biological and Biomedical Sciences program. He looks forward to continuing to explore different realms in science, as well as encouraging other young minority students to do the same. “Growing up, I never expected myself to be here in this position today. Even when I actually got into MIT, I faced a lot of pushback. People questioned my abilities and attributed my successes to luck,” Aceves-Salvador explains.

“It took me four years to leave that mentality. Now, I want to be a driving force to change that stigma. I want people to know that the reason we’re here is because we deserve to be here. And we’re going to do big things just like anyone else.” 

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“Colloidal gels,” ubiquitous in everyday products, divulge their secrets

Researchers at MIT have developed a new method for determining the structure and behavior of a class of widely used soft materials known as weak colloidal gels, which are found in everything from cosmetics to building materials. The study characterizes the gels over their entire evolution, as they change from mineral solutions to elastic gels and then glassy solids.

The work uncovers the microstructural mechanisms underlying how the gels change naturally over time, and how their elastic properties also change, both over time and depending on the rate at which they are experimentally deformed. This characterization should allow further study, prediction, and perhaps manipulation of the gels’ behavior, opening doors to advances in such areas as drug delivery and food production, in which these gels are common ingredients, as well as in applications ranging from water purification to nuclear waste disposal, which use these colloidal gels in a crystallized, porous form known as zeolites.

“We believe this new overall picture and understanding of the gelation and subsequent aging process is of great importance for material scientists who work on soft matter,” says Gareth McKinley, the School of Engineering Professor of Teaching Innovation and professor of mechanical engineering at MIT.

“Our results enable researchers to determine why weak colloidal gels show aspects of both glassy and gel-like behavior, and to possibly engineer the gels to have particular desired features in their mechanical response,” says Bavand Keshavarz, a postdoc in MIT’s Department of Mechanical Engineering and first author of the new study, which appears in PNAS.

The research was performed as part of an international collaboration involving MIT, Argonne National Laboratory, the French National Center for Scientific Research, and the French Alternative Energies and Atomic Energy Commission.

Using aluminosilicate gels, widely utilized for making zeolites, the researchers overcame many of the challenges associated with characterizing these very soft materials, which continuously change over time, as well as exhibiting different properties depending on the rate at which that are deformed. Keshavarz likens their behavior to that of Silly Putty, which stretches and flows if you pull it slowly, but breaks off sharply if you give it a fast tug.

The gels also age quickly, which means that the mechanical behaviors they exhibit, while already varied at differing deformation rates, change quickly over time. Most previous studies focused on studying these materials in their mature state, Keshavarz says.

“They could not get an overall picture of the gel because the experimental window of their observations was rather narrow,” Keshavarz says.

For this study, the researchers realized they could put the gels’ aging process to their advantage through a framework known as “time-connectivity superposition.”

They subjected the alumino-silicates to a repeated series of complex deformation frequencies known as chirps during the gelation and subsequent aging processes. Chirps, modeled after the echolocation signal sequences produced by bats and dolphins, very quickly test the properties of changing soft materials.

By repeatedly applying the chirp signals throughout the evolution of the gels, the researchers developed a sequence of what could be thought of as informational snapshots representing the mechanical properties of the gels as they were subjected to a wide range of deformation frequencies spanning over eight orders of magnitude (for example, from 0.0001 hertz to 10,000 hertz).

“This means we have looked at the material behavior over a very wide range of probing frequencies,” says Keshavarz, “from very slow deformations to very fast ones.”

The resultant snapshots provided a comprehensive profile of the mechanical properties of the gels, allowing the researchers to conclude that weak colloidal gels, also known colloquially as pasty materials, have a dual nature, exhibiting features of both glasses and gels. Prior to this study, researchers’ limited observational perspectives led them to conclude that such materials were either gels or glasses, not having observed both features in a single experiment.

“One scientist says it’s a gel, and the other says it’s a glass. They’re both right,” says McKinley, comparing the gels’ characteristics to that of caramels, which exhibit the same principles of time-connectivity superposition as they are heated and can be either soft and chewy or brittle and glassy.

To observe the evolving structure of aluminosilicate gels, in addition to examining their mechanical properties throughout the gelation and aging process, the researchers applied X-ray scattering. This allowed them to resolve the structure of the gel starting from when its chemical components were smaller than the wavelength of light and therefore invisible without the penetration of X-rays. The process allowed the researchers to observe the physical structure of the gels at length scales ranging over four orders of magnitude, zooming in from a scale of 1 micron down to that of 0.1 nanometer.

Observing the gels at such wide-ranging spatial scales, the researchers discovered that the fractal-like network of connected particles that develops as the particles cluster into a gel remains fixed beyond the gel point. The network grows and adds clusters, changing in scale, but the main structure or “backbone” and geometry remain the same.

Examining the materials over such widely-ranging spatial scales and combining this information with the concurrent information about the materials’ mechanical behavior, the researchers also concluded that larger clusters within the network relaxed more slowly in a gel-like manner after being deformed while the smaller clusters relaxed more quickly like a rigid glassy material. McKinley makes the analogy to the marked differences we experience between the time it takes for a memory foam mattress to recover from being compressed versus the time a very hard conventional mattress takes. Observing this relationship between the size of clusters within the material and the rate of relaxation sheds further light on the origins of these soft materials’ distinctive properties.

“Our work opens up a novel perspective,” says Keshavarz, “and paves the path for researchers to develop a more comprehensive view about the nature of these pasty materials.”

“Colloidal gels are ubiquitous materials,” says Emanuela Del Gado, associate professor in Georgetown University’s Department of Physics, who was not involved in this research but has collaborated with the MIT team in the past. “Their physics is important in so many industries and technologies (from food to paint, to cement, personal care products and biomedical applications). This paper is the first attempt to identify the microscopic traits that unify the mechanics of a potentially wide class of systems, by connecting [the gels’] microstructure to their rheological behavior.”

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In Compton Lecture, Kwame Anthony Appiah analyzes foundations of racism

Philosopher Kwame Anthony Appiah offered a timely commentary while delivering the latest of MIT’s Compton lectures on Thursday, outlining a framework for understanding racism as a tool for social control, and not simply as an expression of prejudice.

“Racism is an ideology, whose effect is to oppress people of one racial identity or maintain unjust advantages for those of another,” Appiah said. “What makes people, beliefs, feelings, institutions, and practices racist is that they contribute to that wrong.”

This view, he said, has multiple implications. For one thing, racial thinking is not borne out of meaningful biological differences; anti-Black racism, for instance, only fully emerged in connection with the development of the modern Atlantic slave trade.

Instead, “Racial groups, like many other groups in society, are people who share a certain social identity — like people who share a gender, a class, a religion, or a nationality,” said Appiah.

Morever, he noted, while those oppressive structures sustain themselves “in part by creating people who are individually racist,” racism stems from “all our social practices, that we build in common.” Disamantling it, he added, “really must be done by we the people, acting together.”

The Compton Lectures are MIT’s most prominent annual speaking series, featuring  experts in a wide range of fields, from politics and government to science, the humanities, music, and journalism. While the lectures are traditionally held on campus in MIT Kresge Auditorium, this year Appiah’s talk, “One Way to Think about Racism,” was delivered via webcast due to the Covid-19 pandemic.

MIT President L. Rafael Reif began the event with introductory remarks, calling Appiah a “pioneering scholar and philosopher” who, in addition to his output of books and academic papers, also acts as “a probing, witty, compassionate, and morally demanding guide” as author of a regular newspaper column, “The Ethicist,” in the Sunday magazine of The New York Times.

A prominent scholar for over three decades, Appiah received his BA and PhD in philosophy from Cambridge University. He taught on the faculties of Yale University, Cornell University, Duke University, and Harvard University, and served as Princeton University’s Laurance S. Rockefeller University Professor of Philosophy and the University Center for Human Values from 2002 through 2014. He has been a professor of philosophy and law at New York University since 2014.

Among Appiah’s highest-profile books are “Cosmopolitanism: Ethics in a World of Strangers,” from 2006; “The Honor Code: How Moral Revolutions Happen,” published in 2010; and “The Lies that Bind: Rethinking Identity,” from 2018. The child of a Ghanian father and English mother, Appiah has woven his personal experiences, family history, and reflections on identity into some of his best-known writings. In 2012, Appiah was awarded the National Humanities Medal by President Barack Obama.

Appiah cited the Harvard University philosopher Tommie Shelby in stating “it helps to think of racism” as an ideology, that is, one of our “widely accepted illusory systems of belief that function to establish or reinforce structures of social oppression.”

Among other things, considering racism in these terms illuminates the reproduction of racial prejudices, since social divisions create conditions in which those prejudices can be widely perpetuated: “Segregation, for example, made it easier to have false belief about other races, because of the way it kept the races apart,” Appiah said.

For this reason among others, Appiah suggested, while racism may be perpetuated by individuals, responsibility also accrues to the society-wide structures that generate racist ideology and allow its transmission among people and over time.

“You can have a racist belief, and it’s a bad thing to have, but [it may be one] for which you are not to blame,” Appiah said. “It’s wrong, but it’s not [necessarily], so to speak, your wrong.”

Regarding the full-blown creation of anti-Black prejudice that arose to justify the Atlantic slave trade, Appiah noted, “Its effect was to rationalize the appalling treatment of Black people that the trade and practice of enslavement involved, as well as to defend, a little bit later, colonial empires.” He added: “We are still living with legacies of that white supremacy.”

A corollary of defining racism in terms of its contributions to larger social inequities, Appiah stated, is that programs such as affirmative action can be consistent with ideals of fairness.

“Racial solidarity among African Americans, given the history of white supremacy, is not a kind of racist ideology, and the attitudes it produces are not racist,” Appiah said, while noting that stereotypes held by members of any group toward any other can be unfair.  

In any event, Appiah pointed out, white Americans have a particular role to play in dismantling anti-Black racism, because of the social advantages afforded them: “When white people … point to acts of anti-Black racism, they’re less likely than Black people of being suspected of being hypersensitive or self-interested. You can also speak up in all-white settings when people venture anti-Black remarks.”

After Appiah’s talk, MIT President L. Rafael Reif moderated a question-and-answer session, reading audience queries to Appiah, including one that asked how institutions can better “identify those embedded, somewhat invisible racist systems” that still exist.

“One kind of institution that should be better at this than most is the university, because we’re full of people who are trying to think outside the box,” Appiah said.

Using the case of the great intellectual W.E.B. Du Bois, the first African American to receive a doctorate from Harvard, Appiah noted, “his experience both as an undergraduate and graduate student … was of course profoundly shaped by the fact that he was surrounded by people who had racist attitudes. Simply letting him in was not enough. I mean, he triumphed anyway, but figuring out how to make him feel that it was his place as much as theirs, that he was as welcome as them … all of that is more complicated than just saying, ‘Okay, come on in.’”

All told, Appiah said, unwinding racist structures is a massive task but one that can be helped by clear recognition of what those structures are and how they function.

“Given its pervasiveness, that’s going to take a while,” Appiah said. “But at least, once we’re clearer about what it [racism] is, we can set about the task, acting, all of us, whatever our racial identity, in a concerted program, to dismantle the racism that has so poisoned the history of this republic of ours, as it has poisoned the history of countries around the world.”

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