A new approach to liquid-repelling surfaces

“Omniphobic” might sound like a way to describe someone who is afraid of everything, but it actually refers to a special type of surface that repels virtually any liquid. Such surfaces could potentially be used in everything from ship hulls that reduce drag and increase efficiency, to coverings that resist stains and protect against damaging chemicals. But the omniphobic surfaces developed so far suffer from a major problem: Condensation can quickly disable their liquid-shedding properties.

Now, researchers at MIT have found a way to overcome this effect, producing a surface design that drastically reduces the effects of condensation, although at a slight sacrifice in performance. The new findings are described in the journal ACS Nano, in a paper by graduate student Kyle Wilke, professor of mechanical engineering and department head Evelyn Wang, and two others.

Creating a surface that can shed virtually all liquids requires a precise kind of texture that creates an array of microscopic air pockets separated by pillars or ridges. These air pockets keep most of the liquid away from direct contact with the surface, preventing it from “wetting,” or spreading out to cover a whole surface. Instead, the liquid beads up into droplets.

“Many liquids are perfectly wetting, meaning the liquid completely spreads out,” says Wilke. These include many of the refrigerants used in air conditioners and refrigerators, hydrocarbons such as those used as fuels and lubricants, and many alcohols. “Those are very difficult to repel. The only way to do it is through very specific surface geometry, which is not that easy to make,” he adds.

Various groups are working on fabrication methods, he says, but with surface features measured in tens of microns (millionths of a meter) or less, “it can make it quite hard to fabricate, and can make the surfaces quite fragile.”

If such surfaces are damaged — for example, if one of the tiny pillars is bent or broken — it can defeat the whole process. “One local defect can destroy the entire surface’s ability to repel liquids,” he says. And condensation, such as dew forming because of a temperature difference between the air and the surface, acts in the same way, destroying the omniphobicity.

“We considered: How can we lose some of the repellency but make the surface robust” against both damage and dew, Wilke says. “We wanted a structure that one defect wouldn’t destroy.” After much calculation and experimentation, they found a geometry that meets that goal thanks, in part, to microscopic air pockets that are disconnected rather than connected on the surfaces, making spreading between pockets much less likely.

The features have to be very small, he explains, because when droplets form they are initially at the scale of nanometers, or billionths of a meter, and the spacing between these growing droplets can be less than a micrometer.

The key architecture the team developed is based on ridges whose profiles resemble a letter T, or in some cases a letter T with serifs (the tiny hooks at the ends of letter strokes in some typefaces). Both the shape itself and the spacing of these ridges are important to achieving the surface’s resistance to damage and condensation. The shapes are designed to use the surface tension of the liquid to prevent it from penetrating the tiny surface pockets of air, and the way the ridges connect prevents any local penetration of the surface cavities from spreading to others nearby — as the team has confirmed in laboratory tests.

The ridges are made in a multistep process using standard microchip manufacturing systems, first etching away the spaces between ridges, then coating the edges of the pillars, then etching away those coatings to create the indentation in the ridges’ sides, leaving a mushroom-like overhang at the top.

Because of the limitations of the current technology, Wilke says, omniphobic surfaces are rarely used today, but improving their durability and resistance to condensation could enable many new uses. The system will need further refinement, though, beyond this initial proof of the concept. Potentially, it could be used to make self-cleaning surfaces, and to improve resistance to ice buildup, to improve the efficiency of heat transfer in industrial processes including power generation, and to reduce drag on surfaces such as the hulls of ships.

Such surfaces could also provide protection against corrosion, by reducing contact between the material surface and any corrosive liquids that it may be exposed to, the researchers say. And because the new method offers a way of precisely designing the surface architecture, Wilke says it can be used for “tailoring how a surface interacts with liquids, such as for tailoring the heat transfer for thermal management in high-performance devices.”

Chang-Jin Kim, a professor of mechanical and aerospace engineering at the University of California at Los Angeles who was not involved in this work, says “One of the most significant limitations of omniphobic surfaces is that, while such a surface has a superior liquid repellency, the entire surface is wetted once the liquid gets into the voids in the textured surface at some locations. This new approach addresses this very limitation.”

Kim adds that “I like that their key idea was based on fundamental science, while their goal was to solve a key real-life problem. The problem they addressed is an important but very difficult one.” And, he says, “This approach can potentially make some of the omniphobic surfaces useful and practical for some important applications.”

The research team also included former graduate students Daniel Preston and Zhengmao Lu. The work was supported by the cooperative agreement between MIT and the Masdar Institute of Science and Technology in Abu Dhabi (now Khalifa University), the Abu Dhabi National Oil Company, the Office of Naval Research, the Air Force Office of Scientific Research, and the National Science Foundation.

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Harnessing the power of sustainable energy

Energy production can be expensive, or inefficient, or toxic to the environment — or some unfortunate combination of the three. But Jesse Hinricher thinks it doesn’t have to be.

Hinricher, an MIT senior majoring in chemical engineering, has been conducting research focused on specialized batteries that could be plugged into the grid to provide renewable energy on demand. Specifically, he works on swapping out some of the pricier electrolytes in so-called redox flow batteries for more abundant ones, which could help make clean energy more affordable.

He cites his rural childhood as the initial source of his passion for environmental conservation. Hinricher grew up on a Minnesota farm, planting and harvesting soybeans, gardening, and tending cattle on his mother’s farm. His mom, who singlehandedly tends the 700-acre family farm, instilled in him the importance of hard work and independence, which remain some of his core values.

“She taught me to value education, and knowledge, and her work ethic has been a source of inspiration to me,” he says.

On a farm, he says, everything is mechanical; he enjoyed working with his hands. That affinity, blended with his drive to develop solutions for climate change, led Hinricher to study chemical engineering. He had seen firsthand how dramatically the seasons changed over years. For him, climate change wasn’t a distant concept; it was an increasingly alarming reality, and one that he felt he couldn’t ignore.

“I enjoy the environment, and I think it needs to be protected,” he says. “And if not me, then who?”

Battery power

Since January 2017, Hinricher has worked in the lab of Fikile Brushett, the Cecil and Ida Green Career Development Associate Professor in the Department of Chemical Engineering, on developing redox flow batteries. In some ways, these are similar to batteries you might put in your TV remote: Electrolytes ferry electrons between a cathode and an anode, producing energy. However, the energy density of redox flow batteries is too small to be used for something like a remote, or even a cell phone. They’d likely be incorporated into large-scale energy grids, and would theoretically be more energy efficient and less geographically dependent than other renewable energy storage devices.

For example, in the middle of the day, solar panels are producing lots of energy, but after the sun sets, they are not. Redox flow batteries can store renewable energy for people to use all day rather than relying on coal or natural gas plants. The pitfall of these batteries currently is that they require rare and expensive materials. That’s where Hinricher’s work comes in; his research focuses on identifying less expensive electrolytes and troubleshooting any flaws in their implementation.

“If we can discover less expensive materials, it makes redox flow batteries more commercially attractive, which would be the coolest thing to ever have contributed to,” he says.

Though Hinricher enjoys his work at MIT, it isn’t where he began his collegiate career. After graduating high school in 2012, he enrolled at the South Dakota School of Mines and Technology. He says that the School of Mines is well-connected, and does an excellent job of preparing its students to enter into industry. However, as much as he liked the applied side of chemical engineering, he was deeply interested in the theoretical aspects as well. He eventually transferred to MIT in fall 2016, excited to delve deeper into the conceptual side.

Before that, though, he carried out research in Professor David Boyles’ group at the School of Mines, working for two years performing organic synthesis of monomer units. This, he says, was where he learned “how rigorous and ultimately gratifying research can be when you care about it and are as passionate as Dr. Boyles was. He imparted that same passion to me.”

Hinricher also took a semester off his studies at Mines to serve as a Lunar Advanced Volatile Analysis subsystem integration and testing intern at NASA. There, he worked on the Resource Prospector Mission, developing analytical instruments for a robot intended to one day go to the moon and search for water.

Then, through a student research program held at Princeton University, he researched polymers that could stitch themselves back together when damaged. At the time he received his acceptance to MIT in 2015, he had ventured out to Berkeley, California, for an internship at the solar technology startup PLANT PV. Hinricher credits the startup’s co-founders, Brian Hardin and Craig Peters, as major influences on his career and mentorship.

“They made me an offer to stay out in California for a year and defer admission here, and I accepted, and had one of the best experiences that I could have asked for,” he says, describing how he saw firsthand to manage a startup and conduct cutting-edge research on renewable energy sources. His experiences also inspired him to dream of starting his own company one day.

Take a hike

Outside of classes, Hinricher likes to stay in touch with the nature that inspired his conservationist outlook in the first place. When he worked for PLANT PV in California, that meant winding through the towering trees of Muir Woods. Now, it’s anything from the White Mountains in New Hampshire to the Arnold Arboretum of Harvard University.

He’s also a member of Trash2Treasure, an MIT recycling program that places donation sites for used items in campus dormitories each spring. Then, in the beginning of the next academic year, T2T sells it back to the student body at a serious discount. One year, the organization managed to save around 250 boxes of items, which is something like 33 tons of material.

“It saves material that would have gone to landfill, and allows students to buy last-minute items very inexpensively,” he says. Anything that the group doesn’t sell is donated to a charitable organization.

In the future, Hinricher says he’d like to keep researching energy storage, and would like to start his own company. Right now, though, he plans to work toward his PhD and see where his research — and the scenic hiking trails along the way — will take him.

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First two-dimensional material that performs as both topological insulator and superconductor

A transistor based on the 2-D material tungsten ditelluride (WTe₂) sandwiched between boron nitride can switch between two different electronic states — one that conducts current only along its edges, making it a topological insulator, and one that conducts current with no resistance, making it a superconductor — researchers at MIT and colleagues from four other institutions have demonstrated.

Using four-probe measurements, a common quantum electronic transport technique to measure the electronic behavior of materials, the researchers plotted the current carrying capacity and resistance characteristics of the two-dimensional tungsten ditelluride transistor and confirmed their findings across a range of applied voltages and external magnetic fields at extremely low temperatures.

“This is the first time that the exact same material can be tuned either to a topological insulator or to a superconductor,” says Pablo Jarillo-Herrero, the Cecil and Ida Green Professor of Physics at MIT. “We can do this by regular electric field effect using regular, standard dielectrics, so basically the same type of technology you use in standard semiconductor electronics.”

New class of materials

“This is the first of a new class of materials — topological insulators that can be tuned electrically into superconductors — which opens many possibilities which before there were significant obstacles to realize,” Jarillo-Herrero says. “Having one material where you can do this seamlessly within the same material to transition between this topological insulator and superconductor is something which is potentially very attractive.”

Tungsten ditelluride, which is one of the transition metal dichalcogenide materials, is classified as a semimetal and conducts electricity like metals in bulk form. The new findings detail that in a single-layer crystal form, at temperatures from less than 1 kelvin to liquid nitrogen range (-320.4 degrees Fahrenheit), tungsten ditelluride hosts three distinct phases: topologically insulating, superconducting, and metallic. An applied voltage drives the transition between these phases, which vary with temperature and electron concentration. In superconducting materials, electrons flow without resistance generating no heat.

The new findings have been published online in the journal Science. Valla Fatemi PhD '18, who is now a postdoc at Yale, and postdoc Sanfeng Wu, who is a Pappalardo Fellow at MIT, are co-first authors of the paper with senior author Jarillo-Herrero. The co-authors are MIT graduate student Yuan Cao; Landry Bretheau PhD '18 of the École Polytechnique in France; Quinn D. Gibson of the University of Liverpool in the UK; Kenji Watanabe and Takashi Taniguchi of the National Institute for Materials Science in Japan; and Robert J. Cava, a professor of chemistry at Princeton University.

Like a quantum wire

The new work builds on a report earlier this year by the researchers demonstrating the quantum spin Hall effect (QSH), which is the signature physics phenomenon underlying two-dimensional topological insulators, in the same single layer tungsten ditelluride material. This edge current is governed by the spin of the electrons rather than by their charge, and electrons of opposite spin move in opposite directions. This topological property is always present in the material at cold temperatures.

This quantum spin Hall effect persisted up to a temperature of about 100 kelvins (-279.67 degrees F). “So it’s the highest temperature 2-D topological insulator so far,” says postdoc Sanfeng Wu, who also was a first author of the earlier paper. “It’s very important for an interesting quantum state like this to survive at high temperatures for use for applications.”

This behavior, in which the edges of tungsten ditelluride material act like a quantum wire, was predicted in 2014 in a theoretical paper by associate professor of physics Liang Fu and Ju Li, a professor of nuclear science and engineering and materials science and engineering. Materials with these qualities are sought for spintronic and quantum computing devices.

Although the topological insulating phenomenon was observed at up to 100 kelvins, the superconducting behavior in the new work occurred at a much lower temperature of about 1K.

This material has the advantage of entering the superconducting state with one of the lowest densities of electrons for any 2-D superconductor. “That means that that small carrier density that is needed to make it a superconductor is one that you can induce with normal dielectrics, with regular dielectrics, and using a small electric field,” Jarillo-Herrero explains.

Addressing the findings of topological insulating behavior in 2-D tungsten telluride in the first paper, and the findings of superconductivity in the second, Wu says, “These are twin papers, each of them is beautiful and put together their combination can be very powerful.” Wu suggests that the findings point the way for investigation of 2-D topological materials and could lead the way to a new material basis for topological quantum computers.

The tungsten ditelluride crystals were grown at Princeton University, while the boron nitride crystals were grown at the National Institute for Materials Science in Japan. The MIT team built the experimental devices, carried out the electronic transport measurements at ultra-cold temperatures, and analyzed the data at the Institute.

Simultaneous discovery

Jarillo-Herrero notes that this discovery that monolayer tungsten ditelluride can be tuned into a superconductor using standard semiconductor nanofabrication and electric field effect techniques was simultaneously realized by a competing group of collaborators, including Professor David Cobden at the University of Washington and Associate Professor Joshua Folk at the University of British Columbia. (Their article — “Gate-induced superconductivity in a monolayer topological insulator” — is being published online at the same time in Science First Release.)

“It was done independently in both groups, but we both made the same discovery,” Jarillo-Herrero says. “It’s the best thing that can happen that your big discovery immediately gets reproduced. It gives extra confidence to the community that this is something that’s very real.”

Jarillo-Herrero was elected as a fellow of the American Physical Society earlier this year based on his seminal contributions to quantum electronic transport and optoelectronics in two-dimensional materials and devices.

Step toward quantum computing

A particular area where this new capability may be useful is the realization of Majorana modes at the interface of topologically insulating and superconducting materials. First predicted by physicists in 1937, Majorana fermions can be thought of as electrons split into two parts, each of which behaves as an independent particle. These fermions have yet to be found as elementary particles in nature but can emerge in certain superconducting materials near absolute zero temperature.

“It is interesting by itself from a fundamental physics point of view, and in addition, it has prospects to be of interest for topological quantum computing, which is a special type of quantum computing,” Jarillo-Herrero says.

The uniqueness of Majorana modes lies in their exotic behavior when one swaps their positions, an operation that physicists call “braiding” because the time dependent traces of these swapping particles look like a braid. The braiding operations can’t change the quantum states of regular particles like electrons or photons, however braiding Majorana particles changes their quantum state completely. This unusual property, dubbed “non-Abelian statistics,” is the key to realizing topological quantum computers. A magnetic gap is also needed for pinning the Majorana mode at a location. 

“This work is quite beautiful,” says Jason Alicea, professor of theoretical physics at Caltech, who was not involved in this research. “The basic ingredients necessary for engineering Majorana modes — superconductivity and gapping of edge states by magnetism — have now been separately demonstrated in WTe₂.”

“Moreover, the observation of intrinsic superconductivity by gating is potentially a major boon for advanced applications of Majorana modes, e.g., braiding to demonstrate non-Abelian statistics. To this end, one can envision designing complex, dynamically tunable networks of superconducting quantum-spin-Hall edge states by electrostatic means.” Alicea says. “The possibilities are very exciting.”

The work was supported by the Gordon and Betty Moore Foundation and also was partly supported by the U.S. Department of Energy Basic Energy Sciences Office, the National Science Foundation, and the Elemental Strategy Initiative in Japan.

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Addressing the possibility of life on Mars

In 2018, millions of people around the world caught glimpses of the planet Mars, discernible as a bright red dot in the summer’s night skies. Every 26 months or so, the red planet reaches a point in its elliptical orbit closest to Earth, setting the stage for exceptional visibility. This proximity also serves as an excellent opportunity for launching exploratory Mars missions, the next of which will occur in 2020 when a global suite of rovers will take off from Earth. 

The red planet was hiding behind the overcast, drizzling Boston sky on Oct. 11, when Mars expert John Grotzinger gave audiences a different perspective, taking them through an exploration of Mars' geologic history. Grotzinger, the Fletcher Jones Professor of Geology at the Caltech and a former professor in the MIT Department of Earth, Atmospheric and Planetary Sciences (EAPS), also used the eighth annual John Carlson Lecture to talk to the audience gathered at the New England Aquarium about the ongoing search for life on Mars.

Specializing in sedimentology and geobiology, Grotzinger has made significant contributions to understanding the early environmental history of the Earth and Mars and their habitability. In addition to involvement with the Mars Exploration Rover (MER) mission and the High Resolution Science Experiment (HiRISE) onboard the Mars Reconnaissance Orbiter (MRO), Grotzinger served as project scientist of the Mars Science Laboratory mission, which operates the Curiosity roving laboratory. Curiosity explores the rocks, soils, and air of the Gale Crater to find out whether Mars ever hosted an environment that was habitable for microbial life during its nearly 4.6-billion-year history.

“What I’d like to do is give you a very broad perspective of how we as scientists go about exploring a planet like Mars, with the rather audacious hypothesis that there could have been once life there,” he told the audience. “This is a classic mission of exploration where a team of scientists heads out into the unknown.”

“Simple one-celled microorganisms we know have existed on Earth for the last three-and-a-half billion years — a long time. They originated, they adapted, they evolved, and they didn’t change very much until you had the emergence of animals just 500 million years ago,” Grotzinger said. “For basically 3 billion years, the planet was pretty much alone with microbes. So, the question is: Could Mars have done something similar?”

Part of the research concerning whether or not Mars ever hosted ancient life involves identifying the environmental characteristics necessary for the survival of living organisms, including liquid water. Currently, the thin atmosphere around Mars prevents the accumulation of a standing body of water, but that may not always have been the case. Topographic features documented by orbiters and landers suggest the presence of ancient river channels, deltas and possibly even an ocean on Mars, “just like we see on Earth,” Grotzinger said. “This tells us that, at least, for some brief period of time if you want to be conservative, or maybe a long period of time, water was there [and] the atmosphere was denser. This is a good thing for life.”

To describe how scientists search for evidence of past habitability on Mars, Grotzinger told the story of stratigraphy — a discipline within geology that focuses on the sequential deposition and layering of sediments and igneous rocks. The changes that occur layer-to-layer indicate shifts in the environmental conditions under which different layers were deposited. In that manner, interpreting stratigraphic records is simple, he said.

“It’s like reading a book. You start at the bottom and you get to the first chapter, and you get to the top and you get to the last chapter,” Grotzinger said. “Sedimentary rocks are records of environmental change … what we want to do is explore this record on Mars.”

While Grotzinger and Curiosity both continue their explorations of Mars, scientists from around the world are working on pinpointing new landing sites for future Mars rovers which will expand the search for ancient life. This past summer, the SAM (Sample Analysis on Mars) instrument aboard the Curiosity rover detected evidence of complex organic matter in Gale Crater, a discovery which further supports the notion that Mars may have been habitable once.

“We know that Earth teems with life and we have enough of a fossil record to know that it’s been that way since we get to the oldest, well-preserved rocks on Earth. But yet, when you go to those rocks, you almost never find evidence of life,” Grotzinger said, leaving space for hope. “And that’s because, in the conversion of the sedimentary environment to the rock, there are enough mineralogic processes that are going on that the record of life gets erased. And so, I think we’re going to have to try over and over again.”

Following the lecture, members and friends of EAPS attended a reception in the main aquarium that featured some of the research currently taking place in the department. Posters and demonstrations were arranged around the aquarium’s cylindrical 200,000-gallon tank simulating a Caribbean coral reef, and attendees were able to chat with presenters and admire aquatic life while learning about current EAPS projects.

EAPS graduate student, postdoc, and research scientist presenters included Tyler Mackey, Andrew Cummings, Marjorie Cantine, Athena Eyster, Adam Jost, and Julia Wilcots from the Bergmann group; Kelsey Moore and Lily Momper from the Bosak group; Eric Beaucé, Ekaterina Bolotskaya, and Eva Golos from the Morgan group; Jonathan Lauderdale and Deepa Rao from the Follows group; Sam Levang from the Flierl group; Joanna Millstein and Kasturi Shah from the Minchew group; and Ainara Sistiaga, Jorsua Herrera, and Angel Mojarro from the Summons group.

The John H. Carlson Lecture series communicates exciting new results in climate science to general audiences. Free of charge and open to the general public, the annual lecture is made possible by a generous gift from MIT alumnus John H. Carlson to the Lorenz Center in the Department of Earth, Atmospheric and Planetary Sciences.

Anyone interested in join the invitation list for next year’s Carlson Lecture is encouraged to contact Angela Ellis.

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Monitoring the atmosphere, changing the world

Measuring the greenhouse and ozone-depleting gas composition of the Earth’s atmosphere continuously for the past 40 years through a global network of sophisticated monitoring stations, the Advanced Global Atmospheric Gases Experiment (AGAGE) has racked up numerous notable achievements.

Among other things, the network’s measurements have helped estimate the lifetimes of ozone-depleting and greenhouse gases in the atmosphere; monitor and pinpoint sources of emissions of chemicals banned by international agreements such as the Montreal Protocol, which outlawed the use of chlorofluorocarbons (CFCs); determine concentrations of the atmosphere’s major cleansing agent, the hydroxyl radical (OH); and provide data to inform international policy discussions concerning atmospheric greenhouse gas emissions.

To celebrate these and other achievements aimed at improving our understanding of key global chemical and climatic phenomena, nearly 40 AGAGE scientists, collaborators, and invited guests from research institutions around the world (many representing dozens more researchers at their home institutions) gathered at a 40th anniversary conference earlier this month at Endicott House. Participants discussed the network’s evolution, impacts, and future.

History

Founded in 1978, AGAGE has also been known as the Global Atmospheric Gases Experiment (GAGE) and the Atmospheric Lifetime Experiment (ALE). Co-founder and leader Ronald Prinn has helped ALE/GAGE/AGAGE merge theory with experimental procedures to measure atmospheric concentrations and thus lifetimes of target gases.

“From the beginning, AGAGE has been a close collaboration between experiment and theory, each informing the other to achieve the siting, frequency, precision and accuracy of measurements needed to answer the scientific questions before us,” said Prinn, an expert in atmospheric chemistry who is director of MIT’s Center for Global Change Science and a professor in the Department of Earth, Atmospheric and Planetary Sciences (EAPS). 

When the network started, those questions included: how frequently to take measurements, where to put measuring stations, how precise to make the measurements, and which gases to measure and which instruments to deploy.

In order to detect and measure the atmospheric concentrations and lifetimes of ozone-depleting and greenhouse gases (GHGs), scientists built measurement instruments and developed computer software to interpret the data. Critical to measuring atmospheric pollutants was to deploy instruments onsite that could take measurements at least four times a day, rather than once a week, the typical rate of gas-measuring stations at the time.

“The goal was to measure ozone-depleting and greenhouse gases onsite at frequencies sufficient to identify both polluted and background air,” Prinn said.

Supported at first by a chemical industry keen on positioning itself to invent replacements for chemicals likely to be banned by international agreements, ALE’s initial goal was to determine the lifetimes of major ozone-depleting gases such as CFCs. The longer they last, the more that get destroyed only in the stratosphere; the shorter they last, the more they can be destroyed in the lower atmosphere before they can damage the ozone layer.

Within three years of deploying four measuring stations, ALE scientists determined that most ozone-depleting gases ended up in the stratosphere. (As it turned out, chemicals engineered to replace ozone-depleting gases were GHGs, known to warm the climate.) Subsequently, NASA, the lead federal agency for upper atmosphere research, became the main supporter of ALE, GAGE and AGAGE. In recent years, AGAGE has become truly international with 13 stations around the world, many of them receiving additional funding from the host nations.

In the 40 years since ALE’s founding, the network’s capabilities have grown significantly through more automation, instruments and stations; more powerful computers; and better computer models. The network first had four stations using gas chromatographs with electron capture detectors (GC-ECDs) measuring five gases four times a day, with sources and sinks inferred using very low-resolution 2-D model. Now there are 13 primary stations with a far more sophisticated set of instruments measuring well over 50 gases 20-40 times per day, with sources and sinks inferred using very high-resolution 3-D models and supercomputers. Today AGAGE data is often combined with NOAA surface data, and NASA and NOAA aircraft and satellite data, yielding a more comprehensive picture of atmospheric gases.

“I think our top accomplishment has been to measure this wide range of gases with precision, and do it in near-real time,” said Peter Simmonds, a visiting professor at the University of Bristol, who has served as an experimentalist throughout the network’s existence. Simmonds, who once built a portable gas chromatograph to measure CFCs, set up two of the first ALE monitoring stations in Ireland and Barbados.

“Our network is unique in that it provides estimates of global, national and city emissions of greenhouse and ozone depleting gases,” said Paul Fraser, an atmospheric chemist who established the network’s first Southern Hemisphere measurements of CFCs in the late-1970s and today calculates emissions using data from the Southern Hemisphere Station in Tasmania. “It allows us to say, yes, we have emissions problems, and this is where they’re coming from. And that enables us to then specifically identify industries that might be involved and to help them in their efforts to reduce these emissions.”

That capability can be critical in ensuring compliance with international environmental agreements such as the Montreal Protocol, said Ray Weiss, a professor at the Scripps Institution of Oceanography at the University of California at San Diego, who has overseen experimental management since joining the network 10 years after its inception — improving station technology and instrumentation calibration, increasing automation of station operations and centralizing data processing over the years.

“The only way to make sure [environmental policies] are working is to quantify what’s actually going into the atmosphere, whether it’s gases that affect climate or the ozone layer,” Weiss said. “The important thing is to keep doing it. It’s not exciting, but it has to be done independently.”

Informing the ban on CFCs

“What an achievement you have had over 40 years of incredible data that allowed you to actually be part of the process that led to a change. You have literally changed the world,” said EAPS Professor Susan Solomon, the conference’s keynote speaker, who described herself as an avid follower of AGAGE’s work and user of its data. Solomon recounted how data on the lifetimes of CFCs informed her research — most notably her discovery of the mechanism behind the formation of the ozone hole above Antarctica, which led to the banning of CFCs through the Montreal Protocol.

Among other things, ALE network methodology and data led to the publication of a paper that was the first to estimate the lifetimes of CFCs, using a top-down analysis that deduced the information from measurements of concentrations of CFCs already in the atmosphere — rather than a time-consuming bottom-up approach that would have entailed evaluating an endless number of alternative processes that skeptics hypothesized would show that CFCs would dissipate long before they could damage the ozone layer. Subsequent papers based on 3-D models and ALE data, established the stratosphere, rather than the lower atmosphere, as the domain where CFCs disintegrate, putting them in prime position to deplete the ozone layer.)

“We have to thank this network for the fact that we didn’t have to go after this in a bottom-up way,” said Solomon. “It’s because of the fact that we could go out and measure the concentrations of these things [that we didn’t] have to fight that bottom-up battle.”

During the Q&A session following her talk, Solomon also noted the value of AGAGE measurements of the important non-carbon-dioxide (non-CO2) greenhouse gases assessed by the Intergovernmental Panel on Climate Change. “There’s plenty to do on [greenhouse] gases that can contribute to global warming,” she said. “Your climate research on [these] gases is incredibly important and will surely be an area of continued need.”

Next steps

AGAGE is now complementing this work with intensified efforts to measure concentrations of more and atmospheric greenhouse gases. As AGAGE expands to take more high-frequency measurements, it also seeks to add many more stations in order to determine country-level emissions with greater accuracy.

Such measurements will be needed to improve understanding of global and regional trends in GHG emissions, and to help verify national and regional compliance to climate action pledges made in the Paris Agreement.

“The Paris Agreement is so loosely written that conformity is unlikely,” Weiss observed. “Anomalies will occur in a lot of places and that will make what we do very important.”

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Youssef Marzouk and Nicolas Hadjiconstantinou to direct the Center for Computational Engineering

Youssef Marzouk and Nicolas Hadjiconstantinou have been named co-directors of MIT’s Center for Computational Engineering (CCE), effective immediately, Anantha Chandrakasan, dean of the School of Engineering, has announced.

“This is an exciting time for computation at MIT, and I’m delighted they have agreed to serve in this important role,” Chadarkasan says. “The CCE has become a hub for some of the most advanced thinking on the science and engineering of computation. Professor Marzouk and Professor Hadjiconstantinou’s deep connections to this community and its pioneering educational programs will make them important partners in our plans for the future.”  

An associate professor in the Department of Aeronautics and Astronautics, Marzouk is also the director of MIT’s Aerospace Computational Design Laboratory and has served as co-director of graduate educational programs for the CCE. He is also a core member of the Statistics and Data Science Center in MIT's Institute for Data, Systems, and Society. His research focuses on uncertainty quantification, inverse problems, statistical inference, and large-scale Bayesian computation for complex physical systems, and on using these approaches to address modeling challenges in energy conversion and environmental applications.

Marzouk received his BS, MS, and PhD degrees in mechanical engineering at the Institute, and spent several years at Sandia National Laboratories before joining the faculty in 2009. He is a recipient of the Hertz Foundation doctoral thesis prize, the Sandia Laboratories Truman Fellowship, the U.S. Department of Energy Early Career Research Award, and the Junior Bose Award for Teaching Excellence from the MIT School of Engineering.     

Hadjiconstantinou is a professor in the Department of Mechanical Engineering and co-director for the CCE’s Computation for Design and Optimization program, as well as its computational science and engineering PhD program. His research interests include kinetic transport for small-scale fluid flow and solid-state heat transfer applications, molecular and stochastic simulation of nanoscale transport phenomena, and molecular and multiscale simulation method development. His research group uses theoretical molecular mechanics approaches, as well as molecular simulation techniques, to develop better understanding, as well as reliable models of nanoscale transport.

Hadjiconstantinou received a BA and MA in engineering from the University of Cambridge, and MS's in both mechanical engineering and physics from MIT, where he also earned his PhD in mechanical engineering. He is a former Lawrence Livermore Fellow and was awarded the Gustus L. Larson Award from the American Society of Mechanical Engineers.     

The Center for Computational Engineering was launched in 2008 and serves as a focal point for research and education in computational science and engineering at MIT. The center has its roots in the Computation for Design and Optimization (CDO) master’s degree program, which first started in 2005. CDO was incorporated into CCE when it was established, and in 2013 the center established a PhD program in computational science and engineering.

The center now comprises faculty and research partners from across the Institute. Its work focuses on advancing computational methodologies for scientific discovery and technological innovation across a spectrum of societally important application areas.      

The CCE’s education programs are, by construction, interdisciplinary. Students in the center’s doctoral program, for example, satisfy departmental requirements with participating partner departments (currently Aeronautics and Astronautics, Civil and Environmental Engineering, Chemical Engineering, Mechanical Engineering, Nuclear Science and Engineering, and Mathematics), but with enhancements that reflect an emphasis on computational engineering. This with-departments curricular structure is already serving as a model for other interdisciplinary doctoral programs at MIT, such as the PhD program in statistics administered within IDSS.      

Marzouk and Hadjiconstantinou replace Anthony Patera, the Ford Foundation Professor of Engineering in the Department of Mechanical Engineering, and Karen Willcox, a former MIT professor of aeronautics and astronautics.

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Squeezing cells to cure diseases

Cell-based immunotherapies, which often involve engineering cells to activate or suppress the immune system, have delivered some dramatic results to cancer patients with few other options. But the complex process of developing these therapies has limited a field that many believe could be a powerful new frontier in medicine.

Using a proprietary platform and an unconventional approach, startup SQZ Biotech is trying to expand immunotherapy’s impact by simplifying the process of engineering immune cells, thus unlocking a slew of new applications for the technology.

SQZ co-founder and CEO Armon Sharei SM ’13 PhD ’13 says his company leverages a simple process — squeezing cells so they can be penetrated by specific molecules — to engineer a broader suite of cell functions than has been possible with the gene therapy approaches that have attracted the bulk of the investments in the field.

In the middle of next year, backed by over $100 million in funding and a collaboration with Roche that could net SQZ over $1 billion in drug development milestone payments, the startup is aiming to begin clinical trials on a treatment targeting human papillomavirus (HPV)-positive tumors. The company’s next potential therapy is aimed at autoimmune diseases including Type 1 diabetes.

Clinical trials will be the true test for a technology that Sharei believes can have a life-altering impact across a variety disease types.

“There’s many things SQZ can do,” Sharei says. “We think [these two clinical programs] are just the beginning.”

A novel approach

CAR T-cell therapies were approved by the U.S. Food and Drug Administration in 2017. They work by extracting a patient’s T cells, known as the soldiers of the immune system, and genetically engineering them to attack cancer cells. The engineered T cells are then injected back into the patient. The process has demonstrated the remarkable potential of immunotherapy, but it is still being refined, has certain limitations, and can be prohibitively expensive.

SQZ’s lead programs avoid genetic engineering to modulate long-term immune responses. The company’s current focus in oncology is on a broad class of cells known as antigen presenting cells, or APCs, which Sharei describes as the “generals of the immune system.” APCs can instruct a patient’s T cells to attack cancerous cells by presenting the right antigens on their surface, in a function of the immune system that occurs naturally.

Engineering APCs to drive specific immune responses has been a struggle for researchers to date, but SQZ has shown that their platform is a simple, scalable way to tackle the issue. The platform works by squeezing a patient’s immune cells through narrow channels on a microfluidic chip, causing the cell membranes temporarily open up. Tumor-associated antigens are inserted into the cells and then naturally present on the cell’s surface, creating an APC. The engineered APCs can then be given back to the patient, where they can instruct the patient’s T cells as they naturally would, offering a relatively simple way to train T cells to attack cancer cells.

Conversely, when SQZ’s technology is used to target autoimmune diseases, red blood cells can be squeezed and manipulated to suppress an immune response, which Sharei says could lead to an innovative approach to treating chronic auto-immune diseases such as Type 1 diabetes.

An unexpected breakthrough

The technology behind SQZ was discovered out of exasperation as much as innovation. It began as a research project in the lab of Klavs Jensen, the Warren K. Lewis Professor of Chemical Engineering and a professor of materials science and engineering at MIT.

For over three years, researchers on the project attempted to shoot materials into cells using a microfluidic device and a jet. The cells proved to be difficult to penetrate, often deflecting away from the jet’s stream, so the team started forcing the cells toward the jet by constricting the cells through smaller channels within the chip. Eventually the project started to yield limited, often uncontrollable, results.

“It was a rough project,” remembers Sharei, who joined the project as a PhD candidate when it was roughly two years old, while being co-advised by Jensen and Robert Langer, the David H. Koch Institute Professor. “There was quite a while when nothing was happening. We kept banging our head against the wall with the jet technique.”

One day the team decided to run the cells through the system without the jet and found that biomaterials in the fluid still entered the cells. That’s when they realized that constricting, or squeezing, the cell was opening up holes in the cell membranes.

The discovery set off a string of experiments to improve the process. In 2013, Sharei, Jensen, and Langer founded SQZ Biotech to share the cell squeezing technology with other research groups. But those collaborations didn’t produce the kind of groundbreaking experiments Sharei and his team were hoping for.

“Companies and academics weren’t really using SQZ for the new things it could do,” Sharei says. “They were using it for the things they could already do, just to do them better. That wasn’t going to have the game changing impact we envisioned for it.”

So SQZ pivoted from providing a lab tool to developing new therapies. Sharei, whose undergraduate work in organic electronics had made him an unlikely participant in the original research project to begin with, found himself with his first full-time job running a company with a unique strategy.

“At the time, the cell therapy industry was very focused on CAR T-cell therapy and gene editing,” Sharei says. “We thought there were much more powerful and simple concepts to implement [with SQZ], and you could hit a lot more diseases. This was an initially difficult message to convey to the field.”

But the broader perception of SQZ changed overnight when the startup signed a partnership with Roche toward the end of 2015, which marked Roche’s first investment in cell-based immunotherapies. Recently, after nearly three years of encouraging preclinical research, Roche announced a dramatic expansion of that partnership, to include more types of APCs in the upcoming clinical trials. The deal gives SQZ $125 million in upfront payments and near-term milestones. On top of that, SQZ may receive development milestone payments of over $1 billion from the pharmaceutical giant. The collaboration also stipulates the two companies could share certain commercial rights to approved products in the future.

The deal gives SQZ some spending power as it tries to strike a balance among pursuing research initiatives internally, partnering with other companies, and granting licenses to outside research groups.

For Sharei, the researcher-turned-CEO, the goal is finding the right path to turn SQZ’s potential into treatments that maximize impact for patients.

“The long-term vision is a company that’s creating many different cell-based therapeutics that have an impact across different disease areas,” Sharei says. “But getting there is all about seeing how these [early trials] do. And as those start to show proof, we can expand into different disease areas as well as broaden the footprint of our early trials.”

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Machines that learn language more like kids do

Children learn language by observing their environment, listening to the people around them, and connecting the dots between what they see and hear. Among other things, this helps children establish their language’s word order, such as where subjects and verbs fall in a sentence.

In computing, learning language is the task of syntactic and semantic parsers. These systems are trained on sentences annotated by humans that describe the structure and meaning behind words. Parsers are becoming increasingly important for web searches, natural-language database querying, and voice-recognition systems such as Alexa and Siri. Soon, they may also be used for home robotics.

But gathering the annotation data can be time-consuming and difficult for less common languages. Additionally, humans don’t always agree on the annotations, and the annotations themselves may not accurately reflect how people naturally speak.

In a paper being presented at this week’s Empirical Methods in Natural Language Processing conference, MIT researchers describe a parser that learns through observation to more closely mimic a child’s language-acquisition process, which could greatly extend the parser’s capabilities. To learn the structure of language, the parser observes captioned videos, with no other information, and associates the words with recorded objects and actions. Given a new sentence, the parser can then use what it’s learned about the structure of the language to accurately predict a sentence’s meaning, without the video.

This “weakly supervised” approach — meaning it requires limited training data — mimics how children can observe the world around them and learn language, without anyone providing direct context. The approach could expand the types of data and reduce the effort needed for training parsers, according to the researchers. A few directly annotated sentences, for instance, could be combined with many captioned videos, which are easier to come by, to improve performance.

In the future, the parser could be used to improve natural interaction between humans and personal robots. A robot equipped with the parser, for instance, could constantly observe its environment to reinforce its understanding of spoken commands, including when the spoken sentences aren’t fully grammatical or clear. “People talk to each other in partial sentences, run-on thoughts, and jumbled language. You want a robot in your home that will adapt to their particular way of speaking … and still figure out what they mean,” says co-author Andrei Barbu, a researcher in the Computer Science and Artificial Intelligence Laboratory (CSAIL) and the Center for Brains, Minds, and Machines (CBMM) within MIT’s McGovern Institute.

The parser could also help researchers better understand how young children learn language. “A child has access to redundant, complementary information from different modalities, including hearing parents and siblings talk about the world, as well as tactile information and visual information, [which help him or her] to understand the world,” says co-author Boris Katz, a principal research scientist and head of the InfoLab Group at CSAIL. “It’s an amazing puzzle, to process all this simultaneous sensory input. This work is part of bigger piece to understand how this kind of learning happens in the world.”

Co-authors on the paper are: first author Candace Ross, a graduate student in the Department of Electrical Engineering and Computer Science and CSAIL, and a researcher in CBMM; Yevgeni Berzak PhD ’17, a postdoc in the Computational Psycholinguistics Group in the Department of Brain and Cognitive Sciences; and CSAIL graduate student Battushig Myanganbayar.

Visual learner

For their work, the researchers combined a semantic parser with a computer-vision component trained in object, human, and activity recognition in video. Semantic parsers are generally trained on sentences annotated with code that ascribes meaning to each word and the relationships between the words. Some have been trained on still images or computer simulations.

The new parser is the first to be trained using video, Ross says. In part, videos are more useful in reducing ambiguity. If the parser is unsure about, say, an action or object in a sentence, it can reference the video to clear things up. “There are temporal components — objects interacting with each other and with people — and high-level properties you wouldn’t see in a still image or just in language,” Ross says.

The researchers compiled a dataset of about 400 videos depicting people carrying out a number of actions, including picking up an object or putting it down, and walking toward an object. Participants on the crowdsourcing platform Mechanical Turk then provided 1,200 captions for those videos. They set aside 840 video-caption examples for training and tuning, and used 360 for testing. One advantage of using vision-based parsing is “you don’t need nearly as much data — although if you had [the data], you could scale up to huge datasets,” Barbu says.

In training, the researchers gave the parser the objective of determining whether a sentence accurately describes a given video. They fed the parser a video and matching caption. The parser extracts possible meanings of the caption as logical mathematical expressions. The sentence, “The woman is picking up an apple,” for instance, may be expressed as: λxy. woman x, pick_up x y, apple y.

Those expressions and the video are inputted to the computer-vision algorithm, called “Sentence Tracker,” developed by Barbu and other researchers. The algorithm looks at each video frame to track how objects and people transform over time, to determine if actions are playing out as described. In this way, it determines if the meaning is possibly true of the video.

Connecting the dots

The expression with the most closely matching representations for objects, humans, and actions becomes the most likely meaning of the caption. The expression, initially, may refer to many different objects and actions in the video, but the set of possible meanings serves as a training signal that helps the parser continuously winnow down possibilities. “By assuming that all of the sentences must follow the same rules, that they all come from the same language, and seeing many captioned videos, you can narrow down the meanings further,” Barbu says.

In short, the parser learns through passive observation: To determine if a caption is true of a video, the parser by necessity must identify the highest probability meaning of the caption. “The only way to figure out if the sentence is true of a video [is] to go through this intermediate step of, ‘What does the sentence mean?’ Otherwise, you have no idea how to connect the two,” Barbu explains. “We don’t give the system the meaning for the sentence. We say, ‘There’s a sentence and a video. The sentence has to be true of the video. Figure out some intermediate representation that makes it true of the video.’”

The training produces a syntactic and semantic grammar for the words it’s learned. Given a new sentence, the parser no longer requires videos, but leverages its grammar and lexicon to determine sentence structure and meaning.

Ultimately, this process is learning “as if you’re a kid,” Barbu says. “You see world around you and hear people speaking to learn meaning. One day, I can give you a sentence and ask what it means and, even without a visual, you know the meaning.”

“This research is exactly the right direction for natural language processing,” says Stefanie Tellex, a professor of computer science at Brown University who focuses on helping robots use natural language to communicate with humans. “To interpret grounded language, we need semantic representations, but it is not practicable to make it available at training time. Instead, this work captures representations of compositional structure using context from captioned videos. This is the paper I have been waiting for!”

In future work, the researchers are interested in modeling interactions, not just passive observations. “Children interact with the environment as they’re learning. Our idea is to have a model that would also use perception to learn,” Ross says.

This work was supported, in part, by the CBMM, the National Science Foundation, a Ford Foundation Graduate Research Fellowship, the Toyota Research Institute, and the MIT-IBM Brain-Inspired Multimedia Comprehension project.

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Scene at MIT: Happy Nanoween

As part of her research on nanomaterials, PhD student Ashley Kaiser recently grew millions of carbon nanotubes — each incredibly strong and only 1/10,000 the width of a human hair — and immersed them in a guiding liquid. Upon drying, the resulting nanotube "forest" created a recognizable spooky pattern.

"The initial motivation behind this work was to densify carbon nanotube forests into predictable, cellular patterns by gently wetting them with a liquid, a process that can help enable scalable nanomaterial manufacturing," says Kaiser, who studies in the lab of Professor Brian Wardle. "The pattern was not precisely planned. While I knew that the carbon nanotubes would form cell-like shapes, I didn't know that these three particular sections would spell out 'Boo' so nicely, so it was a pretty special find."

The image was captured using a scanning electron microscope, which produces images in greyscale; the orange color was added later as a special effect. "It was exciting to find this under the microscope, and I thought that it would be great for Halloween the moment I saw it!" Kaiser says.

Submitted by: William Litant/Department of Aeronautics and Astronautics | Image by: Ashley Kaiser

Have a creative photo of campus life you'd like to share? Submit it to Scene at MIT.

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The BSU at 50

In 1968, the black student community at MIT was small and needed a way to amplify its voice. Formed during that tumultuous year in political and racial history in the U.S., the MIT Black Students’ Union (BSU) launched a journey of advocacy and community that now continues 50 years later.

In the late 1960s, about 11 percent of Americans were black, but each 1,000-member class at MIT had perhaps half a dozen black students. Galvanized by the assassination of Martin Luther King Jr., black student groups were forming at overwhelmingly white college campuses across the country, and MIT was no exception. The students who started MIT BSU had two goals in mind: to support each other and to bring more black students to the Institute. “Surely there were more than three blacks in the high school class of 1965 who could belong to the MIT tribe,” says Linda C. Sharpe ’69, one of the BSU founders, who is a past president of the MIT Alumni Association and a former MIT Corporation member.

In fall of 1968, the new group drew up and presented a list of recommendations to the MIT administration: increasing the number of black students, creating a pre-­enrollment summer program for minority students, and hiring more minority faculty members. In response, MIT established the Task Force on Educational Opportunity (TFEO), which was made up of a group of BSU representatives and MIT administrators and chaired by associate provost (and future MIT president) Paul Gray ’54, SM ’55, ScD ’60. Through a series of often intense discussions, the TFEO designed the summer program, called Project Interphase, and came up with more inclusive approaches to things like recruitment, admissions, and financial aid.

“The Institute rolled up its sleeves and attacked [the recommendations] in the MIT way — that is, being very analytical about what the challenges and problems were, and then trying to figure out solutions to those challenges,” says founding BSU co-chair Shirley Ann Jackson ’68, PhD ’73, who went on to become the first black woman to earn a PhD from MIT and is now the president of Rensselaer Polytechnic Institute and a life member of the MIT Corporation. “That doesn’t mean there wasn’t great emotion around it, because there really, really was on all sides.”

Other key players in the birth of the BSU were founding cochair James Turner, PhD ’71, Jennifer Rudd ’68, Charles Kidwell ’69, Nathan Seely ’70, Sekazi Mtingwa ’71, Fred Johnson ’72, and Ronald Mickens, who was a postdoctoral associate in physics.

Gray, who died in 2017, would ultimately recall that being part of the Task Force was eye-opening: “I came away with an understanding I had none of two years before, as best a white person can understand what it was like to be black in the United States in the era before and during the civil rights revolution. It was a powerful experience.”

Through the efforts of the Admissions Office and BSU members who began recruiting black applicants from all over the country, the number of African-American students jumped to about 50 in the Class of 1973 and continued to rise, as did the numbers of women and other members of underrepresented minorities. Meanwhile, in an event modeled after political takeovers of buildings on other college campuses, a group of black students disrupted a meeting of the MIT Corporation in 1970 to advocate for the BSU demands and support kitchen workers involved in a labor dispute.

“The BSU has always played a major role in helping the Institute to not fall back from the goals of commitment and participation of black students, faculty, and administration. It’s been a key agent in helping MIT look at itself,” says adjunct professor emeritus of urban studies Clarence Williams, HM ’09, who joined the MIT administration in 1972 as assistant dean of the graduate school and has since served in multiple positions, including as acting director of the Office of Minority Education, special assistant to the president and chancellor, and Institute ombudsperson. Williams, who started the Black History Project in 1995, is the author of Technology and the Dream: Reflections on the Black Experience at MIT, 1941–1999 (MIT Press, 2001) and co-produced the 1996 video “It’s Intuitively Obvious,” which documented the experience of black students at MIT.

In addition to working to increase the number of black students on campus, the BSU advocated for recruitment and retention of black faculty and staff. “We also sought to broaden the dialogue on campus around issues pertinent to our community,” says Michelle Harton ’83, the outgoing chair of Black Alumni of MIT (BAMIT). Over the years, the BSU has organized discussion panels and cultural events, hosted prospective minority students, and played a central role in MIT’s annual Black History Month observance. Among the speakers brought to campus by the BSU are Benjamin L. Hooks, then executive director of the NAACP, and Ivan Van Sertima, author of They Came Before Columbus: The African Presence in Ancient America.

Five decades after the formation of the BSU, black students now make up 6.2 percent of MIT’s undergraduate population (as of fall 2017), up from 0.6 percent in 1968. And Sharpe notes that today, “the number of black women in the freshman class is nearly equal to the number of all women in my class.” She adds, “Times do change, if a lot more slowly than we would like.”

And the work continues today. In a parallel to the 1968 BSU proposals, the BSU and the Black Graduate Student Association (BGSA) met with President L. Rafael Reif in 2015, following several racially charged incidents across the country. The two groups issued a set of recommendations that included diversity orientation and training for all students, a diversity representative within each department, an MIT Medical clinician specializing in psychological issues affecting African-Americans, and a requirement that all undergraduates take an “immersion studies” elective focusing on multiculturalism or diversity. BAMIT and other groups also made recommendations. Many have already been completely or partially implemented, and conversations on how to advance other recommendations on the departmental level are ongoing.

“The work that needs to be done at MIT is similar to what needs to take place across the country — greater cultural understanding and value for the differences that people bring, plus mechanisms for civil discourse,” says Elaine Harris ’78, a BAMIT board member and cosponsor of what’s now called the Hack for Inclusion, an annual hackathon to tackle issues of bias, diversity, and inclusion. Outcomes from the hackathon include projects to create a more welcoming Boston for the black community and to address bias in machine learning. “I wish that the problem-­solving skills we apply to technical challenges and the metrics we develop to assess progress could be used in the domain of diversity, equity, and inclusion,” she says.

The BSU held an on-campus event in February to celebrate its 50-year legacy of advocating for black students and all minorities at MIT. In June, Jackson and Rudd — the first two black women to earn undergraduate degrees at MIT — became the first black women to earn their red jackets at their 50th reunion, where Jackson also served as a class speaker. In November, she is slated to speak at the BAMIT capstone event, “Road to 50: The Power of Community,” which will feature historical recollections, discussions, and a look forward.

Kelvin Green ’21, current cochair of the BSU, believes the organization is still playing an integral part to ensure equality within the MIT community, and that’s one of the reasons why he chose the Institute.

“Diversity is but a stepping-stone toward a higher goal,” he says. “Inclusion — truly valuing the people brought to this campus in all of the identities they bring — is where we must look. Let us not stop at the stepping-stone of diversity and ponder why it cannot support our weight; we must transition to the rock of inclusion, which is by definition created to support us all.”

This article originally appeared in the MIT News section of the November/December 2018 issue of MIT Technology Review magazine.

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Letter from President Reif: Consoling each other and helping to heal the world

The following email was sent today to the MIT community by President L. Rafael Reif.

To the members of the MIT community,

As our nation once again confronts heartbreaking mass violence, sending this annual reminder of MIT’s policies against harassment may feel to some as inconsequential and almost irrelevant.

Yet these policies could not have greater consequence, because they embody our conviction that the ultimate measure of our community is how we treat one another.

By reminding us that violence, racism, harassment and bullying are out of bounds – period – our policies can help lead us from error. Yet they cannot lead us towards the light: the essential duty to treat each other with respect, sympathy, decency, humility and kindness; the responsibility each of us has to make sure that everyone at MIT can truly feel at home; the challenge of finding a way to repair our fractured nation. This work we must do for ourselves.

Our policies also demonstrate that official statements matter – for good or ill. For instance, a recent draft of a government policy would redefine gender in a way that would erase the dignity and lived reality of well over a million transgender Americans, including many members of our MIT community. And next week in Massachusetts, the civil rights of these Americans are up for a vote.

Let me be clear: No matter how government policy may change, it will not change or weaken MIT’s commitment to protecting the rights and safety of every member of the MIT community.

Ultimately, nothing we do or say at MIT can reverse the fact that, from Pittsburgh to Jeffersontown, Charleston to Orlando, a baseball field in Maryland to the Boston Marathon, fellow human beings have been targeted and killed for being themselves.

Against the backdrop of our daily lives, such hatred and violence are much too frequent now. But we can and must fight the numb helplessness that might allow these acts to ever feel “normal.” We must keep ourselves alive to the shock and the pain, and stay focused on finding a better path for our society.

Tomorrow our community will come together to honor those killed or injured and those who helped them, and to console each other.

Vigil for Hope in the Face of Hate
Wednesday, October 31
12:30 PM
Steps of the Student Center (W20)

I am grateful for the way we live and work together at MIT. I am proud that we do not fear each other or the world. As one can see any day in the Infinite Corridor, our openness to talent from every faith, culture, nation and background is central to our success, and central to our humanity. We should never forget the value and strength of this deeply American idea.

In this difficult time, we must use the strength, ingenuity and optimism of our community to help heal the world.

Sincerely,

L. Rafael Reif

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Analyzing the 2018 election: Insights from MIT scholars

For the 2018 version of the Election Insights series, MIT humanities, arts, and social science faculty members are offering research-based perspectives on issues of importance to the country — ranging from the future of work to national security to civic discourse and the role that, as the Constitution states, "we, the people" have in the defense of democracy itself.

In addition to commentaries, the series also includes "Music for the Midterms," a lively playlist created by our music faculty, and an annotated election booklist consisting of nine works selected by MIT humanities scholars for their value illuminating this moment in American history.

Please, remember to vote on or before Nov. 6.

Commentary: On civil society and the defense of democracy

"What is written in a constitution can take a nation only so far unless society is willing to act to protect it. Every constitutional design has its loopholes, and every age brings its new challenges, which even farsighted constitutional designers cannot anticipate. We have to keep reminding ourselves that the future of our much-cherished institutions depends not on others but on ourselves, and that we are all individually responsible for our institutions." —Daron Acemoglu, the Elizabeth and James Killian Professor of Economics  Read more >>

Commentary: On partisan politics

"Partisan polarization is one of most important political developments of the past half-century. Of course, Democrats and Republicans have always taken divergent positions on issues ranging from slavery to internal improvements. Nevertheless, contemporary polarization differs from that of earlier eras, if only because the U.S. government directly shapes the lives of so many more people, in the U.S. and around the world." —Devin Caughey, associate professor of political science  Read more >>

Commentary: On media technology and immigration policy

"Widespread access to social media lowers the barrier for communities that have been marginalized by mass media and makes it easier for them to gain visibility and adherents. How might any of this affect the midterm elections? Here are three brief hypotheses, based on my ongoing research into the relationship between media technologies and social movements." —Sasha Costanza-Chock, associate professor of civic media Read more >>

Commentary: On democracy and civic discourse

"Elections are helpful reminders (as if we needed any) that we do not all agree. Yet, we must somehow figure out how to get along despite our disagreements. In particular, we may wonder whether, and to what extent, we should tolerate views we disagree with. In some cases, a well-functioning discursive market — a public forum of diverse views — may require us to respond to certain views with 'discursive intolerance." —Justin Khoo, Associate Professor of Philosophy  Read more >>

Commentary: On female candidates of color

“A record number of women have filed as candidates this year, and a record number have won primaries in House and Senate races. Women of color make up one-third of the women candidates for the House, and three of four female gubernatorial nominees are women of color." —Helen Elaine Lee, professor of writing  Read more >>

Commentary: On social media and youth political engagement

"Although discussions about youth and new media tend to assume that something about the technology itself is responsible for political and social changes, in fact, the political possibilities associated with contemporary media are highly contingent upon societal power structures.” —Jennifer Light, the Bern Dibner Professor of the History of Science and Technology  Read more >>

Commentary: On the U.S.-North Korea relationship

"The North Korean nuclear program is not something to be 'solved' — that window has closed — it is an issue to be managed. The good news is that the United States has a lot of experience managing the emergence of new nuclear weapons powers." —Vipin Narang, associate professor of political science  Read more >>

Commentary: On reducing gun violence

"America’s gun culture is a resilient fact of political life. Attempts to reverse the country’s appetite for firearms have largely failed, even as gun violence persists at an astonishing pace. Lately, however, a social movement to challenge gun culture has rocked politics for the first time in a generation." —John Tirman, executive director and principal research scientist in the Center for International Studies  Read more >>

Commentary: On American identity

"The stories and interpretations that different groups of Americans offer of economic changes, including the loss of manufacturing jobs and growing inequality, are central to how they understand their own social positions as well as the kinds of economic and political futures they can envision. Many Americans are now struggling for a way to understand and talk about these economic changes — changes that are also apparent in other wealthy countries but more extreme in the United States.” —Christine Walley, professor of anthropology  Read more >>

Playlist: Music for the Midterms

As America heads toward the 2018 midterm elections on Nov. 6, MIT Music faculty offer a wide-ranging playlist — from Verdi to Gershwin to Lin-Manuel Miranda — along with notes on why each work resonates with this election season.  Access the playlist >>

Annotated election booklist: Reading for the Midterms

As the 2018 midterms approach, MIT writers and scholars in the humanities offer a selection of nine books — along with notes on why each work is illuminating for this moment in American political history. Browse the booklist >>

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Model paves way for faster, more efficient translations of more languages

MIT researchers have developed a novel “unsupervised” language translation model — meaning it runs without the need for human annotations and guidance — that could lead to faster, more efficient computer-based translations of far more languages.

Translation systems from Google, Facebook, and Amazon require training models to look for patterns in millions of documents — such as legal and political documents, or news articles — that have been translated into various languages by humans. Given new words in one language, they can then find the matching words and phrases in the other language.

But this translational data is time consuming and difficult to gather, and simply may not exist for many of the 7,000 languages spoken worldwide. Recently, researchers have been developing “monolingual” models that make translations between texts in two languages, but without direct translational information between the two.

In a paper being presented this week at the Conference on Empirical Methods in Natural Language Processing, researchers from MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) describe a model that runs faster and more efficiently than these monolingual models.

The model leverages a metric in statistics, called Gromov-Wasserstein distance, that essentially measures distances between points in one computational space and matches them to similarly distanced points in another space. They apply that technique to “word embeddings” of two languages, which are words represented as vectors — basically, arrays of numbers — with words of similar meanings clustered closer together. In doing so, the model quickly aligns the words, or vectors, in both embeddings that are most closely correlated by relative distances, meaning they’re likely to be direct translations.

In experiments, the researchers’ model performed as accurately as state-of-the-art monolingual models — and sometimes more accurately — but much more quickly and using only a fraction of the computation power.

“The model sees the words in the two languages as sets of vectors, and maps [those vectors] from one set to the other by essentially preserving relationships,” says the paper’s co-author Tommi Jaakkola, a CSAIL researcher and the Thomas Siebel Professor in the Department of Electrical Engineering and Computer Science and the Institute for Data, Systems, and Society. “The approach could help translate low-resource languages or dialects, so long as they come with enough monolingual content.”

The model represents a step toward one of the major goals of machine translation, which is fully unsupervised word alignment, says first author David Alvarez-Melis, a CSAIL PhD student: “If you don’t have any data that matches two languages … you can map two languages and, using these distance measurements, align them.”

Relationships matter most

Aligning word embeddings for unsupervised machine translation isn’t a new concept. Recent work trains neural networks to match vectors directly in word embeddings, or matrices, from two languages together. But these methods require a lot of tweaking during training to get the alignments exactly right, which is inefficient and time consuming.

Measuring and matching vectors based on relational distances, on the other hand, is a far more efficient method that doesn’t require much fine-tuning. No matter where word vectors fall in a given matrix, the relationship between the words, meaning their distances, will remain the same. For instance, the vector for “father” may fall in completely different areas in two matrices. But vectors for “father” and “mother” will most likely always be close together.

“Those distances are invariant,” Alvarez-Melis says. “By looking at distance, and not the absolute positions of vectors, then you can skip the alignment and go directly to matching the correspondences between vectors.”

That’s where Gromov-Wasserstein comes in handy. The technique has been used in computer science for, say, helping align image pixels in graphic design. But the metric seemed “tailor made” for word alignment, Alvarez-Melis says: “If there are points, or words, that are close together in one space, Gromov-Wasserstein is automatically going to try to find the corresponding cluster of points in the other space.”

For training and testing, the researchers used a dataset of publicly available word embeddings, called FASTTEXT, with 110 language pairs. In these embeddings, and others, words that appear more and more frequently in similar contexts have closely matching vectors. “Mother” and “father” will usually be close together but both farther away from, say, “house.”

Providing a “soft translation”

The model notes vectors that are closely related yet different from the others, and assigns a probability that similarly distanced vectors in the other embedding will correspond. It’s kind of like a “soft translation,” Alvarez-Melis says, “because instead of just returning a single word translation, it tells you ‘this vector, or word, has a strong correspondence with this word, or words, in the other language.’”

An example would be in the months of the year, which appear closely together in many languages. The model will see a cluster of 12 vectors that are clustered in one embedding and a remarkably similar cluster in the other embedding. “The model doesn’t know these are months,” Alvarez-Melis says. “It just knows there is a cluster of 12 points that aligns with a cluster of 12 points in the other language, but they’re different to the rest of the words, so they probably go together well. By finding these correspondences for each word, it then aligns the whole space simultaneously.”

The researchers hope the work serves as a “feasibility check,” Jaakkola says, to apply Gromov-Wasserstein method to machine-translation systems to run faster, more efficiently, and gain access to many more languages.

Additionally, a possible perk of the model is that it automatically produces a value that can be interpreted as quantifying, on a numerical scale, the similarity between languages. This may be useful for linguistics studies, the researchers say. The model calculates how distant all vectors are from one another in two embeddings, which depends on sentence structure and other factors. If vectors are all really close, they’ll score closer to 0, and the farther apart they are, the higher the score. Similar Romance languages such as French and Italian, for instance, score close to 1, while classic Chinese scores between 6 and 9 with other major languages.

“This gives you a nice, simple number for how similar languages are … and can be used to draw insights about the relationships between languages,” Alvarez-Melis says.

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Inside these fibers, droplets are on the move

Microfluidics devices are tiny systems with microscopic channels that can be used for chemical or biomedical testing and research. In a potentially game-changing advance, MIT researchers have now incorporated microfluidics systems into individual fibers, making it possible to process much larger volumes of fluid, in more complex ways. In a sense, the advance opens up a new “macro” era of microfluidics.

Traditional microfluidics devices, developed and used extensively over the last couple of decades, are manufactured onto microchip-like structures and provide ways of mixing, separating, and testing fluids in microscopic volumes. Medical tests that only require a tiny droplet of blood, for example, often rely on microfluidics. But the diminutive scale of these devices also poses limitations; for example, they generally aren’t useful for procedures that need larger volumes of liquid to detect substances present in minute amounts.

A team of MIT researchers found a way around that, by making microfluidic channels inside fibers. The fibers be made as long as needed to accommodate larger throughput, and they offer great control and flexibility over the shapes and dimensions of the channels. The new concept is described in a paper appearing this week in the journal Proceedings of the National Academy of Sciences, written by MIT graduate student Rodger Yuan, professors Joel Voldman and Yoel Fink, and four others.

A multidisciplinary approach

The project came about as a result of a “speedstorming” event (an amalgam of brainstorming and speed dating, an idea initiated by Professor Jeffrey Grossman) that was instigated by Fink when he was director of MIT’s Research Laboratory of Electronics. The events are intended to help researchers develop new collaborative projects, by having pairs of students and postdocs brainstorm for six minutes at a time and come up with hundreds of ideas in an hour, which are ranked and evaluated by a panel. In this particular speedstorming session, students in electrical engineering worked with others in materials science and microsystems technology to develop a novel approach to cell sorting using a new class of multimaterial fibers.

Yuan explains that, although microfluidic technology has been extensively developed and widely used for processing small amounts of liquid, it suffers from three inherent limitations related to the devices’ overall size, their channel profiles, and the difficulty of incorporating additional materials such as electrodes.

Because they are typically made using chip-manufacturing methods, microfluidic devices are limited to the size of the silicon wafers used in such systems, which are no more than about 8 inches across. And the photolithography methods used to make such chips limit the shapes of the channels; they can only have square or rectangular cross sections. Finally, any additional materials, such as electrodes for sensing or manipulating the channels’ contents, must be individually placed in position in a separate process, severely limiting their complexity.

“Silicon chip technology is really good at making rectangular profiles, but anything beyond that requires really specialized techniques,” says Yuan, who carried out the work as part of his doctoral research. “They can make triangles, but only with certain specific angles.” With the new fiber-based method he and his team developed, a variety of cross-sectional shapes for the channels can be implemented, including star, cross, or bowtie shapes that may be useful for particular applications, such as automatically sorting different types of cells in a biological sample.

In addition, for conventional microfluidics, elements such as sensing or heating wires, or piezoelectric devices to induce vibrations in the sampled fluids, must be added at a later processing stage. But they can be completely integrated into the channels in the new fiber-based system.

A shrinking profile

Like other complex fiber systems developed over the years in the laboratory of co-author Yoel Fink, professor of materials science and engineering and head of the Advanced Functional Fabrics of America (AFFOA) consortium, these fibers are made by starting with an oversized polymer cylinder called a preform. These preforms contain the exact shape and materials desired for the final fiber, but in much larger form — which makes them much easier to make in very precise configurations. Then, the preform is heated and loaded into a drop tower, where it is slowly pulled through a nozzle that constricts it to a narrow fiber that’s one-fortieth the diameter of the preform, while preserving all the internal shapes and arrangements.

In the process, the material is also elongated by a factor of 1,600, so that a 100-millimeter-long (4-inch-long) preform, for example, becomes a fiber 160 meters long (about 525 feet), thus dramatically overcoming the length limitations inherent in present microfluidic devices. This can be crucial for some applications, such as detecting microscopic objects that exist in very small concentrations in the fluid — for example, a small number of cancerous cells among millions of normal cells.

“Sometimes you need to process a lot of material because what you’re looking for is rare,” says Voldman, a professor of electrical engineering who specializes in biological microtechnology. That makes this new fiber-based microfluidics technology especially appropriate for such uses, he says, because “the fibers can be made arbitrarily long,” allowing more time for the liquid to remain inside the channel and interact with it.

While traditional microfluidics devices can make long channels by looping back and forth on a small chip, the resulting twists and turns change the profile of the channel and affect the way the liquid flows, whereas in the fiber version these can be made as long as needed, with no changes in shape or direction, allowing uninterrupted flow, Yuan says.

The system also allows electrical components such as conductive wires to be incorporated into the fiber. These can be used for example to manipulate cells, using a method called dielectrophoresis, in which cells are affected differently by an electric field produced between two conductive wires on the sides of the channel.

With these conductive wires in the microchannel, one can control the voltage so the forces are “pushing and pulling on the cells, and you can do it at high flow rates,” Voldman says.

As a demonstration, the team made a version of the long-channel fiber device designed to separate cells, sorting dead cells from living ones, and proved its efficiency in accomplishing this task. With further development, they expect to be able to perform more subtle discrimination between cell types, Yuan says.

“For me this was a wonderful example of how proximity between research groups at an interdisciplinary lab like RLE leads to groundbreaking research, initiated and led by a graduate student. We the faculty were essentially dragged in by our students,” Fink says.

The researchers emphasize that they do not see the new method as a substitute for present microfluidics, which work very well for many applications. “It’s not meant to replace; it’s meant to augment” present methods, Voldman says, allowing some new functions for particular uses that have not previously been possible.

“Exemplifying the power of interdisciplinary collaboration, a new understanding arises here from unexpected combinations of manufacturing, materials science, biological flow physics, and microsystems design,” says Amy Herr, a professor of bioengineering at the University of California at Berkeley, who was not involved in this research. She adds that this work “adds important degrees of freedom — regarding geometry of fiber cross-section and material properties — to emerging fiber-based microfluidic design strategies.”

The team included graduate student Jaemyon Lee, Hao Wei Su PhD ’16, and postdocs Etgar Levy and Tural Khudryev. The work was supported by the National Science Foundation, the National Institutes of Health, the Defense Advanced Research Projects Agency, the U.S. Army Research Laboratory and the U.S. Army Research Office through the Institute for Soldier Nanotechnologies at MIT, and the Center for Materials Science and Engineering.

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3Q: Alyce Johnson on upholding the rights of MIT’s transgender community

When Massachusetts voters head to the polls on Nov. 6 for the 2018 midterm election, one of the items they’ll find on the ballot is Question 3, about whether to uphold a 2016 state law barring discrimination against transgender people in public spaces such as stores and restaurants.

With the election drawing near, MIT News spoke with interim Institute Community and Equity Officer Alyce Johnson, who leads the ICEO in its mission to advance a respectful and caring community that embraces diversity and empowers everyone to learn and do their best at MIT.

Johnson spoke about the Institute’s commitment to protecting the rights of transgender members of the MIT community, regardless of the ballot initiative’s outcome, and why respectful, open dialogue is an essential component of MIT’s campus life.

Q: What would be the effect on MIT policies if Question 3 does not pass, and the law protecting transgender people from discrimination in public places is overturned?

A: MIT’s senior administration and I want our community to know that our support for MIT’s transgender community is steadfast, and that the Institute’s nondiscrimination policy, which expressly prohibits discrimination based on gender identity, will remain in place if the state law is repealed following the Nov. 6 election. The same will be true if the federal government more narrowly defines gender under federal law, a change that is reportedly under consideration. I want to reassure our community that MIT is permitted to offer antidiscrimination protections that are broader than what is protected by state and federal law. The Institute’s policies will continue to prohibit discrimination or harassment at MIT based on sex, sexual orientation, and gender identity.

In addition to the policies we have in place, our unwavering commitment to the rights of transgender students, staff, and faculty will also continue regardless of the outcome of the election or of any potential federal policy changes. As just one example, the pilot project to designate certain all-gender restrooms on campus will keep moving forward.

We are working very hard to provide resources and support for those who feel under attack or not safe. The chancellor’s office is doing a great job, with events planned through the Division of Student Life and the Office of Minority Education (OME), of providing welcoming spaces for students during and after the election. The Rainbow Lounge and SPXCE Intercultural Center will both have open houses on Nov. 6 and Nov. 7. And, on Nov. 7, students can gather in the Student Center (PDR 1 and 2) from 3 to 5 p.m. for cookies, community, and conversation. OME is holding several events, including Let’s Chat in the OME with Student Mental Health and Counseling on Nov. 6 from 5:20 to 7 p.m. on Nov. 6 and on Nov. 7 from 3:00 to 5 p.m. 

For faculty, staff, postdocs, and family members, My Life Services offers expert counseling support and resources. The LBGTQ Employee Resource Group is also available to support our employees.

Q: For many, anticipation about the outcome of the November elections is high. Can you talk about why being active, engaged citizens, as well as promoting respectful dialogue among people with different political beliefs, is important to the MIT community and a priority for the ICEO?

A: This moment offers an opportunity to recommit to our values around mutual respect, openness, and integrity at MIT. Regardless of differences in opinion, we are committed to looking after each other, whatever the issue is, in the best of times and the worst of times.

The MIT culture rests with its citizens. We are a community that includes differences, and acknowledges and leverages those differences through studying and working together, and by having conversations that bring greater understanding of each other. It makes us a better organization when we can honor our differences and learn to have civil discourse in conversations about difficult topics. I learn from you because the lens through which you see things is different from my own lens. That’s what promotes understanding.

Q: One of the ways the ICEO operates is to partner and coordinate with other offices and organizations at MIT working to further diversity, inclusion, and civic engagement. From this vantage point, can you describe some of the activities on campus in the days leading up to the election?

A: There has been a surge of activities to help raise awareness and get out the vote at MIT. The ICEO recently partnered with the LBGTQ Employee Resource Group for an event we called “ICEO Community Town Hall: Trans Rights.” The session focused on a discussion about the current state of transgender rights in Massachusetts, and featured MIT students, alumni, staff, and faculty members.

Last year, a group of undergraduate and graduate students, the chancellor’s office, registrar, and Priscilla King Gray Public (PKG) Service Center implemented TurboVote, a nonpartisan, nonprofit platform, to increase voting and voter registration, and it’s been exciting to watch the initiative expand this fall.

A new nonpartisan student group called MITvote 2018, which works closely with the PKG Service Center, has been focused on voter registration and education. Through their work this fall, they’ve registered 1,056 people, which they estimate to be 13 percent of the eligible student voter population. On Oct. 30, they will be hosting a nonpartisan explanation of Massachusetts ballot races and initiatives with student political organizations in Room 4-370 from 7 to 8:30 p.m.

And, in response to Question 3, a group of students formed “Yes on 3.” Through information sessions and study breaks, this group has been raising awareness among students that transgender protection is an issue in the Massachusetts 2018 election, and they’ve been working to register students to vote.

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