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Imaging system helps surgeons remove tiny ovarian tumors

Tue, 04/23/2019 - 11:59pm

Ovarian cancer is usually diagnosed only after it has reached an advanced stage, with many tumors spread throughout the abdomen. Most patients undergo surgery to remove as many of these tumors as possible, but because some are so small and widespread, it is difficult to eradicate all of them.

Researchers at MIT, working with surgeons and oncologists at Massachusetts General Hospital (MGH), have now developed a way to improve the accuracy of this surgery, called debulking. Using a novel fluorescence imaging system, they were able to find and remove tumors as small as 0.3 millimeters — smaller than a poppy seed — during surgery in mice. Mice that underwent this type of image-guided surgery survived 40 percent longer than those who had tumors removed without the guided system.

“What’s nice about this system is that it allows for real-time information about the size, depth, and distribution of tumors,” says Angela Belcher, the James Mason Crafts Professor of Biological Engineering and Materials Science at MIT, a member of the Koch Institute for Integrative Cancer Research, and the recently appointed head of MIT’s Department of Biological Engineering.

The researchers are now seeking FDA approval for a phase 1 clinical trial to test the imaging system in human patients. In the future, they hope to adapt the system for monitoring patients at risk for tumor recurrence, and eventually for early diagnosis of ovarian cancer, which is easier to treat if it is caught earlier.

Belcher and Michael Birrer, formerly the director of medical gynecologic oncology at MGH and now the director of the O’Neal Comprehensive Cancer Center at the University of Alabama at Birmingham, are the senior authors of the study, published online in the journal ACS Nano this week.

Neelkanth Bardhan, a Mazumdar-Shaw International Oncology Fellow at the Koch Institute, and Lorenzo Ceppi, a researcher at MGH, are the lead authors of the paper. Other authors include MGH researcher YoungJeong Na, MIT Lincoln Laboratory technical staff members Andrew Siegel and Nandini Rajan, Robert Fruscio of the University of Milan-Bicocca, and Marcela del Carmen, a gynecologic oncologist at MGH and chief medical officer of the Massachusetts General Physicians Organization.

Glowing tumors

Because there is no good way to detect early-stage ovarian cancer, it is one of the most difficult types of cancer to treat. Of 250,000 new cases diagnosed each year worldwide, 75 percent are in an advanced stage. In the United States, the five-year combined survival rate for all stages of ovarian cancer is 47 percent, only a slight improvement from 38 percent three decades ago, despite the advent of chemotherapeutic drugs such as cisplatin, approved by the FDA in 1978 for ovarian cancer treatment. In contrast, the five-year combined survival rate for all stages of breast cancer has steadily improved, from around 75 percent in the 1970s to over 90 percent now.  

“We desperately need better upfront therapies, including surgery, for these (ovarian cancer) patients,” Birrer says.

Belcher and Birrer joined forces to work on this problem through the Bridge Project, a collaboration between the Koch Institute and Dana-Farber/Harvard Cancer Center. Belcher’s lab has been developing a novel type of medical imaging based on light in the near-infrared (NIR) spectrum. In a paper published in March, she reported that this imaging system could achieve an unprecedented combination of resolution and penetration-depth in living tissue.

In the new study, Belcher, Birrer, and their colleagues worked with researchers at MIT Lincoln Laboratory to adapt NIR imaging to help surgeons locate tumors during ovarian cancer surgery, by providing continuous, real-time imaging of the abdomen, with tumors highlighted by fluorescence. Previous analyses have shown that survival rates are strongly inversely correlated with the amount of residual tumor mass left behind in the patient during debulking surgery, but many ovarian tumors are so small or hidden that surgeons can’t find them.

To make the tumors visible, the researchers designed chemical probes using single-walled carbon nanotubes that emit fluorescent light when illuminated by a laser. They coated these nanotubes with a peptide that binds to SPARC, a protein that is overexpressed by highly invasive ovarian cancer cells. This probe binds to the tumors and makes them fluoresce at NIR wavelengths, allowing surgeons to more easily find them with fluorescence imaging.

The researchers tested the image-guided system in mice that had ovarian tumors implanted in a region of the abdominal cavity known as the intraperitoneal space, and showed that surgeons were able to locate and remove tumors as small as 0.3 millimeters. Ten days after surgery, these mice had no detectable tumors, while mice that had undergone the traditional, non-image-guided surgery, had many residual tumors missed by the surgeon.

By three weeks after the surgery, many of the tumors had grown back in the mice that underwent image-guided surgery, but those mice still had a median survival rate that was 40 percent longer than that of mice that underwent traditional surgery.

No other imaging system would be able to locate tumors that small during a surgical procedure, the researchers say.

“You can’t have a patient in a CT machine or an MRI machine and have the surgeon perform this surgical debulking procedure at the same time, and you can’t expose the patient to X-ray radiation for multiple hours of the long surgery. This optics-based imaging system allows us to do that in a safe manner,” Bardhan says.

Alessandro Santin, a professor of obstetrics and gynecology and clinical research program leader at the Yale University School of Medicine, described the results as “intriguing.”

“These data support the potential use of this novel imaging system in the intraoperative setting for the optical detection of residual malignant tissue at the time of surgical staging, and/or cytoreductive surgery in ovarian cancer patients,” says Santin, who was not involved in the study.

Monitoring patients

For most ovarian cancer patients, tumor debulking surgery is followed by chemotherapy, so the researchers now plan to do another study where they treat the mice with chemotherapy after image-guided surgery, in hopes of preventing the remaining tiny tumors from spreading.

“We know that the amount of tumor removed at the time of surgery for patients with advanced-stage ovarian cancer is directly correlated with their outcome,” Birrer says. “This imaging device will now allow the surgeon to go beyond the limits of resecting tumors visible to the naked eye, and should usher in a new age of effective debulking surgery.”

Now that they have demonstrated that this concept can be successfully applied to imaging during surgery, the researchers hope to begin adapting the system for use in human patients.

“In principle, it’s quite doable,” Siegel says. “It’s purely the mechanics and the funding at this point, because this mouse experiment serves as the proof of principle and may actually have been more challenging than building a human-scale system.”

The researchers also hope to deploy this type of imaging to monitor patients after surgery, and eventually to develop it as a diagnostic tool for screening women at high risk for developing ovarian cancer.

“A major focus for us right now is developing the technology to be able diagnose ovarian cancer early, in stage 1 or stage 2, before the disease becomes disseminated,” Belcher says. “That could have a huge impact on survival rates, because survival is related to the stage of detection.”

The research was funded, in part, by the Bridge Project and the Koch Institute Support (core) Grant from the National Cancer Institute, with previous support for the development of the system from the Koch Institute Frontier Research Program and the Kathy and Curt Marble Cancer Research Fund.

Water Innovation Prize goes to startups targeting methane and wastewater

Tue, 04/23/2019 - 4:34pm

A startup with a cheap technology for purifying textile wastewater and another with a system to help reduce methane emissions from cattle were named co-winners of the MIT Water Innovation Prize on Thursday.

After eight student finalist teams pitched their companies’ water-related solutions, the judges couldn’t agree on the winners and ultimately split the grand prize into two $14,000 checks for the co-winners.

The founders of both the seaweed-producing startup Symbrosia and the textile wastewater purification startup SiPure said they were happy to split the winnings.

“We were just so proud to be here,” SiPure business development lead Lily Cheng Zedler said after the event. “We’re really grateful to the Water Innovation Prize and the judges for believing in us.”

Close to 200 people, including students, faculty, investors, and people working in the private industry, traveled to the sixth floor of the Media Lab for the event. Members from the eight finalist teams came from as far away as Lebanon and as close as the MIT Sloan School of Management to share their ideas.

The third place, $7,000 prize went to Volta Irrigation, which loans seeds, fertilizers, and pesticides to smallholder farmers in Rwanda and surrounding countries, then helps the farmers increase their productivity by loaning them a proprietary irrigation system called the Alma Volta. The stationary, bicycle-like device works by having operators pedal, which powers an inverter, battery, and pump that efficiently distribute over 3,000 liters of water per hour onto crops.

Addressing livestock methane emissions

According to the Environmental Protection Agency, methane accounts for about 10 percent of U.S. greenhouse gas emissions. The largest source of methane is livestock such as cows, pigs, and goats, who produce it as part of their normal digestive processes.

Recent research has shown that mixing just 2 percent of a specific kind of algae into a cow’s diet can reduce their methane emissions by 99 percent.

Symbrosia is acting on those findings with a patent-pending system that consists of a tank for growing that algae, a tank for growing shrimp, and chambers that move waste and water back and forth. When waste from the shrimp moves to the algae tank it acts as fertilizer, and as the algae absorb nutrients from the water it produces clean, oxygenated water for the shrimp.

The result is a weekly harvest of algae and local, organic shrimp (which are grown in three-month rotational cycles). The only water loss in the system is due to evaporation, and all of the waste is dissolved back into the water, according to the company. Symbrosia plans to sell the algae to feed suppliers at $1.60 a pound, and the shrimp to restaurants at $24 a pound.

With its algae, the company plans to first target the mixed-ration dairy feed supplement market, estimated to be around $5.3 billion in size. With its shrimp, the company will first target the $31 million imported organic shrimp market in the U.S.

The company will begin its first pilot project with three corporate partners at Port Hueneme in California toward the end of this year. Eventually, it plans to place large versions of its system near livestock industry hot spots to maximize its impact.

Cleaning up the textile industry

Garment manufacturers use huge volumes of water each year to dye fabrics. Purifying the resulting wastewater is a complex, expensive process that can account for up to 25 percent of the operating costs of a standard textile mill.

Unfortunately, the low margins in the textile industry lead many manufacturers to dump the wastewater in local waterways. For example, in India, the world’s second largest producer of textiles, 80 percent of textile wastewater goes untreated, according to SiPure.

Wastewater dumping leads to the pollution of drinking water, destruction of local agriculture, and long-term health consequences for people in the area.

SiPure has developed and patented a silicon membrane that it says makes the process of purifying textile wastewater dramatically simpler and cheaper. Billions of tiny nanopores within the membrane allow water to flow through while molecular dyes get stuck.

“It looks boring on the surface, just a gray square,” SiPure co-founder Brendan Smith, who invented the technology during his PhD work in MIT’s Department of Materials Science and Engineering, told the audience during the pitch. “But the magic is in the cross section.”

Smith says the membrane is capable of removing more than 99 percent of the dyes in waters and can be produced for about 10 times less than competing ceramic-based purification technology. SiPure says its membrane also decreases maintenance costs while working for around 10 years.

This summer, the company is starting a pilot project with a textile mill in India, where its membranes will purify 50 to 100 liters of wastewater each day. From there, the founders plan to continue scaling throughout India in hopes of capturing 35 to 40 percent of the market by 2025.

The Water Innovation Prize, which helps translate research and ideas into business and impact, has been hosted by the MIT Water Club since 2015. Each year, student-led finalist teams from around the country and, increasingly, the world, come to MIT’s campus to pitch their water-related innovations.

“Nanofiber yarn” makes for stretchy, protective artificial tissue

Tue, 04/23/2019 - 4:29pm

The human body is held together by an intricate cable system of tendons and muscles, engineered by nature to be tough and highly stretchable. An injury to any of these tissues, particularly in a major joint like the shoulder or knee, can require surgical repairs and weeks of limited mobility to fully heal.

Now MIT engineers have come up with a tissue engineering design that may enable flexible range of motion in injured tendons and muscles during healing.

The team has engineered small coils lined with living cells, that they say could act as stretchy scaffolds for repairing damaged muscles and tendons. The coils are made from hundreds of thousands of biocompatible nanofibers, tightly twisted into coils resembling miniature nautical rope, or yarn.

The researchers coated the yarn with living cells, including muscle and mesenchymal stem cells, which naturally grow and align along the yarn, into patterns similar to muscle tissue. The researchers found the yarn’s coiled configuration helps to keep cells alive and growing, even as the team stretched and bent the yarn multiple times.

In the future, the researchers envision doctors could line patients’ damaged tendons and muscles with this new flexible material, which would be coated with the same cells that make up the injured tissue. The “yarn’s” stretchiness could help maintain a patient’s range of motion while new cells continue to grow to replace the injured tissue.

“When you repair muscle or tendon, you really have to fix their movement for a period of time, by wearing a boot, for example,” says Ming Guo, assistant professor of mechanical engineering at MIT. “With this nanofiber yarn, the hope is, you won’t have to wearing anything like that.”

Guo and his colleagues published their results this week in the Proceedings of the National Academy of Sciences. His MIT co-authors are Yiwei Li, Yukun Hao, Satish Gupta, and Jiliang Hu. The team also includes Fengyun Guo, Yaqiong Wang, Nü Wang, and Yong Zhao, of Beihang University.

Stuck on gum

The new nanofiber yarn was inspired in part by the group’s previous work on lobster membranes, where they found the crustacean’s tough yet stretchy underbelly is due to a layered, plywood-like structure. Each microscopic layer contains hundreds of thousands of nanofibers, all aligned in the same direction, at an angle that is slightly offset from the layer just above and below.

The nanofibers’ precise alignment makes each individual layer highly stretchable in the direction in which the fibers are arranged. Guo, whose work focuses on biomechanics, saw the lobster’s natural stretchy patterning as an inspiration for designing artificial tissues, particularly for high-stretch regions of the body such as the shoulder and knee.

Guo says biomedical engineers have embedded muscle cells in other stretchy materials such as hydrogels, in attempts to fashion flexible artificial tissues. However, while the hydrogels themselves are stretchy and tough, the embedded cells tend to snap when stretched, like tissue paper stuck on a piece of gum.

“When you largely deform a material like hydrogel, it will be stretched just fine, but the cells can’t take it,” Guo says. “A living cell is sensitive, and when you stretch them, they die.”

Shelter in a slinky

The researchers realized that simply considering the stretchability of a material would not be enough to design an artificial tissue. That material would also have to be able to protect cells from the severe strains produced when the material is stretched.

The team looked to actual muscles and tendons for further inspiration, and observed that the tissues are made from strands of aligned protein fibers, coiled together to form microscopic helices, along which muscle cells grow. It turns out that, when the protein coils stretch out, the muscle cells simply rotate, like tiny pieces of tissue paper stuck on a slinky.

Guo looked to replicate this natural, stretchy, cell-protecting structure as an artificial tissue material. To do so, the team first created hundreds of thousands of aligned nanofibers, using electrospinning, a technique that uses electric force to spin ultrathin fibers out from a solution of polymer or other materials. In this case, he generated nanofibers made from biocompatible materials such as cellulose.

The team then bundled aligned fibers together and twisted them slowly to form first a spiral, and then an even tighter coil, ultimately resembling yarn and measuring about half a millimeter wide. Finally, they seeded live cells along each coil, including muscle cells, mesenchymal stem cells, and human breast cancer cells.

The researchers then repeatedly stretched each coil up to six times its original length, and found that the majority of cells on each coil remained alive and continued to grow as the coils were stretched. Interestingly, when they seeded cells on looser, spiral-shaped structures made from the same materials, they found cells were less likely to remain alive. Guo says the structure of the tighter coils seems to “shelter” cells from damage.

Going forward, the group plans to fabricate similar coils from other biocompatible materials such as silk, which could ultimately be injected into an injured tissue. The coils could provide a temporary, flexible scaffold for new cells to grow. Once the cells successfully repair an injury, the scaffold can dissolve away.

“We may be able to one day embed these structures under the skin, and the [coil] material would eventually be digested, while the new cells stay put,” Guo says. “The nice thing about this method is, it’s really general, and we can try different materials. This may push the limit of tissue engineering a lot.”

This research was funded, in part, by MIT Research Support Committee Fund.

NEET welcomes Boeing sponsorship

Tue, 04/23/2019 - 3:45pm

A cross-departmental engineering program focused on modern industry and real-world projects is welcoming a new sponsor and industry collaborator: aerospace company Boeing.

This is a deeply beneficial industry collaboration for the New Engineering Education Transformation (NEET) program, which launched in 2017 to reimagine engineering education at MIT, says NEET Executive Director Amitava "Babi" Mitra.

A cross-disciplinary endeavor with a focus on integrative, project-centric learning, NEET cultivates the essential skills, knowledge, and qualities to help students build the “new machines and systems” that will be required to address the formidable challenges posed by the 21st century.

“Industry experts bring a flavor of real life into the projects,” Mitra says of the NEET program, which is offering five threads — Advanced Materials Machines, Autonomous Machines, Digital Cities, Living Machines, and Renewable Energy Machines.

“Projects are more engaging for students when we can connect them to what’s happening in industry,” says Mitra. Students in NEET earn a degree in their chosen major and are simultaneously awarded a NEET certificate in their chosen thread.

This fall, Boeing will become a founding co-sponsor of the Autonomous Machines thread. Alexa Jan, a senior in the Department of Electrical Engineering and Computer Science and NEET participant, calls this news exciting.

“A collaboration with Boeing will provide more resources for interdisciplinary projects that will help students be leaders in the autonomous machines field and beyond,” she says.

The close proximity of Aurora Flight Sciences, a Boeing company, will enable frequent interactions between students and autonomy and robotics experts from industry, says Jonathan P. How, the Richard Cockburn Maclaurin Professor of Aeronautics and Astronautics, who leads the Autonomous Machines thread.

“This collaboration will provide students with a wealth of experience on the needs for advanced autonomy in complex systems and a better understanding of how to implement those algorithms,” says How. He has worked with Boeing on research for more than a decade.

The collaboration was celebrated when Boeing representatives visited campus visit on April 17 for a series of meetings with administrators, faculty, and students.

“This partnership fits with our strategy for the Boeing Aerospace and Autonomy Center at Kendall Square, which will advance the enabling technologies for autonomous aircraft,” says Greg Hyslop, Boeing chief technology officer and senior vice president of engineering, test, and technology. “We see great benefit in supporting MIT students challenged with developing real-world autonomy solutions.”

Top collegiate inventors awarded 2019 Lemelson-MIT Student Prize

Tue, 04/23/2019 - 12:30pm

Following a nationwide search for the most inventive college students, the Lemelson-MIT Program today announced the winners of the 2019 Lemelson-MIT Student Prize. The prize recognizes young inventors who have dedicated themselves to solving global problems. This year’s inventions range from innovative, low-cost cancer screening tools to an affordable clean water system, which ensures homes and families have clean, safe water. 

The Lemelson-MIT Student Prize is supported by The Lemelson Foundation, and serves as a catalyst for young inventors in the fields of health care, transportation and mobility, food/water and agriculture, and consumer devices. The program awarded a total of $90,000 in prizes to three undergraduate teams and four individual graduate student inventors, selected from a large and highly competitive pool of applicants from across the United States. Students were selected based on a variety of factors including: the overall inventiveness of their work, the invention’s potential for commercialization or adoption, and youth mentorship experience.

“We are inspired by the revolutionary work of this year’s winners. All of the inventions are designed with the intention of making the world a better place,” said Professor Michael J. Cima, faculty director of the Lemelson-MIT Program and associate dean of innovation within the MIT School of Engineering. “We are proud of how dedicated these young inventors are to combatting real-world problems.”

“We congratulate this year’s winners for their outstanding work tackling significant challenges in order to improve lives both in the United States and around the world,” said Carol Dahl, executive director at The Lemelson Foundation. “This diverse group of students drives home the opportunity that exists to inspire young minds across the country to create the essential inventions of today and tomorrow.”

2019 Lemelson-MIT Student Prize Winners 

The “Cure it!” Lemelson-MIT Student Prize rewards technology-based inventions that involve health care. The winners are:

The majority of cervical cancer-related deaths occur in low and middle-income countries due to the lack of affordable screening technology. Mercy invented the Callascope, a high quality, low-cost, speculum-free device for cervical cancer screening and prevention. The device can be easily inserted into the vagina, like a tampon, either by a physician or for self-imaging/screening. It is fitted with a consumer-grade light source and camera to take images of the cervix from inside the body. The Callascope provides a cost-effective option for cervical cancer screenings in low-resource settings with limited available technologies. It can be connected to a mobile phone, tablet, or computer, and is coupled with an algorithm that uses machine learning to classify cervix images as normal or pre-cancerous.

The Ithemba team created a reusable, affordable, and contamination-free core needle breast biopsy device that is designed to support earlier breast cancer detection in low-resource settings. The reusable devices currently available on the market are expensive and require a 24-hour cleaning process. Ithemba’s novel device is not only affordable, but can also be sterilized instantly with a bleach wipe. With Ithemba’s device, performing breast biopsies will be significantly less expensive for hospitals and physicians in low-resource settings, and much safer for their patients.

The “Eat it!” Lemelson-MIT Student Prize rewards technology-based inventions that involve food/water and agriculture. The winners are:

Mullen’s company, Aclarity LLC, offers a scalable electrochemical water purification technology marketed initially for residential use that uses low amounts of electricity to zap contaminants in water through advanced oxidation reactions. The technology disinfects pathogens, destroys organic contaminants, removes metals, and normalizes pH to produce truly clean and safe water. It reduces maintenance, uses low energy and purifies water faster and more efficiently than conventional treatment methods in the U.S. and globally.

The BioEnergy Project is a compact and scalable food-waste-to-food-and-fuel system that converts food waste from dining halls and restaurants into both nutrient-rich organic fertilizer that can be used to grow more food, as well as electricity that is generated from biogas. Right now, 40 percent of all food produced is wasted and dumped into landfills. When food decomposes in a landfill it generates methane, which is released into the atmosphere. Currently, food waste is responsible for 8 percent of the total anthropogenic greenhouse gas emissions globally. The BioEnergy Project’s invention is a cyclical system that can tackle the environmental and agricultural concerns of food insecurity, the need for renewable energy sources, and addresses climate change by capturing and utilizing a methane source that would otherwise be released into the atmosphere from landfills.

The “Move it!” Lemelson-MIT Student Prize rewards technology-based inventions that involve transportation and mobility. The winners are:

Scurti developed an internal monitoring system for high-temperature superconductors (HTS), consisting of a sensing system to detect local, incipient failures in the HTS wire that generates the magnetic field needed to operate electric motors or magnetic levitation (MagLev) trains. The sensing system is based on optical fibers embedded into superconducting wires that are able to prevent failure of the superconductor. This invention allows for reliable operation of HTS systems, thereby bringing HTS materials and systems to fruition via applications such as electric motors for carbon-free ships and aircrafts, carbon-free, high-speed MagLev trains, and nuclear fusion reactors for power generation.

Portal Entryways is a wireless device that opens disabled-accessible doors when a user approaches with the Portal smartphone application. A small wireless receiver is installed on the door and the user’s Portal app uses proximity to tell the door when to open upon approach. In addition to benefitting people with mobility-related disabilities, the system also enables facilities managers to track door usage data in order to maintain accessibility.

The “Use it!” Lemelson-MIT Student Prize rewards technology-based inventions that involve consumer devices. The winners are:

The headset-like device, AlterEgo, is a sensory and auditory feedback system that uses neuromuscular signals from the brain’s speech system to extract speech. When we talk to ourselves internally, our brain transmits electrical signals to the vocal cords and internal muscles involved in speech production. With AlterEgo, an artificial intelligence agent is able to make sense of these signals and prepare a response. The user can hear the AI agent’s responses through vibrations in the skull and inner ear, thus making the process entirely internal. The AI agent can also send the information to a computer, to help an individual with a speech disability communicate in real-time.

Students interested in applying for the 2020 Lemelson-MIT Student Prize can find more information here. The 2020 Student Prize application will open in May.

Improving security as artificial intelligence moves to smartphones

Tue, 04/23/2019 - 11:00am

Smartphones, security cameras, and speakers are just a few of the devices that will soon be running more artificial intelligence software to speed up image- and speech-processing tasks. A compression technique known as quantization is smoothing the way by making deep learning models smaller to reduce computation and energy costs. But smaller models, it turns out, make it easier for malicious attackers to trick an AI system into misbehaving — a concern as more complex decision-making is handed off to machines. 

In a new study, MIT and IBM researchers show just how vulnerable compressed AI models are to adversarial attack, and they offer a fix: add a mathematical constraint during the quantization process to reduce the odds that an AI will fall prey to a slightly modified image and misclassify what they see. 

When a deep learning model is reduced from the standard 32 bits to a lower bit length, it’s more likely to misclassify altered images due to an error amplification effect: The manipulated image becomes more distorted with each extra layer of processing. By the end, the model is more likely to mistake a bird for a cat, for example, or a frog for a deer.   

Models quantized to 8 bits or fewer are more susceptible to adversarial attacks, the researchers show, with accuracy falling from an already low 30-40 percent to less than 10 percent as bit width declines. But controlling the Lipschitz constraint during quantization restores some resilience. When the researchers added the constraint, they saw small performance gains in an attack, with the smaller models in some cases outperforming the 32-bit model. 

“Our technique limits error amplification and can even make compressed deep learning models more robust than full-precision models,” says Song Han, an assistant professor in MIT’s Department of Electrical Engineering and Computer Science and a member of MIT’s Microsystems Technology Laboratories. “With proper quantization, we can limit the error.” 

The team plans to further improve the technique by training it on larger datasets and applying it to a wider range of models. “Deep learning models need to be fast and secure as they move into a world of internet-connected devices,” says study coauthor Chuang Gan, a researcher at the MIT-IBM Watson AI Lab. “Our Defensive Quantization technique helps on both fronts.”

The researchers, who include MIT graduate student Ji Lin, present their results at the International Conference on Learning Representations in May.

In making AI models smaller so that they run faster and use less energy, Han is using AI itself to push the limits of model compression technology. In related recent work, Han and his colleagues show how reinforcement learning can be used to automatically find the smallest bit length for each layer in a quantized model based on how quickly the device running the model can process images. This flexible bit width approach reduces latency and energy use by as much as 200 percent compared to a fixed, 8-bit model, says Han. The researchers will present their results at the Computer Vision and Pattern Recognition conference in June. 

Nine universities team up to create global infrastructure for digital academic credentials

Tue, 04/23/2019 - 10:40am

While digital technology has started to transform education by enabling new learning pathways that are customized to each individual’s needs, the way that educational institutions issue and manage academic credentials has not changed much. Nine leading universities announced that they have formed the Digital Credentials collaboration in order to create a trusted, distributed, and shared infrastructure standard for issuing, storing, displaying, and verifying academic credentials.

“Currently, those who successfully complete a degree from an institution must go back to that institution — sometimes by mail or even in person — each time there is a need to verify the academic credentials earned,” says Sanjay Sarma, MIT vice president for open learning. “This can be a complicated problem, especially if the learner no longer has access to the university. Such is the case with many refugees, immigrants, and displaced populations.” 

The universities working on this effort include Delft University of Technology in the Netherlands; Harvard University Division of Continuing Education; Hasso Plattner Institute at the University of Potsdam in Germany; MIT; Tecnologico de Monterrey in Mexico; Technical University of Munich in Germany; University of California at Berkeley; University of California at Irvine; and the University of Toronto in Canada. 

“As teaching and learning offered by our universities has come to encompass digital platforms, and as each of our learners have gained the power to shape their own educational trajectory over a lifetime, the question of trusted verification and authentication of learning and credentials poses itself with broad urgency,” says Diana Wu, dean of university extension and new academic ventures at UC Berkeley.

Using technology that relies on strong cryptography to prevent tampering and fraud, and shared ledgers to create a global infrastructure for anchoring academic achievements, the researchers plan to build upon earlier research and pioneering efforts by their institutions — including MIT’s pilot program for issuing all of its graduates a digital version of their diploma that is verified against a blockchain. 

One of the driving forces behind this shared effort is the interest by universities to utilize the advances brought by these new technologies in a way that prioritizes the needs of learners. Digital credentials allow learners to maintain a compelling and verifiable digital record of their lifelong learning achievements that may include badges, internships, bootcamps, certificates, MicroMasters (graduate-level courses), and stackable combinations thereof, as well as traditional degrees — all of which they can easily share with employers or other institutions. Institutions can record and manage the achievements of their learners in a way that is easy, safe, and inexpensive, and minimizes the risk of identity fraud.

“We are well-positioned in academia to use cutting-edge technology to empower learners to advance their careers and education with credentials in the palms of their hands,” says Hans Pongratz, senior vice president for information technology systems and services at Technical University of Munich.

The team has now set their sights on the evolution and governance of a shared standard. “Digital credentials are like tokens of social and human capital and hold tremendous value for the individual. The crucial opportunity we have today is to bring together institutions that share a commitment to the benefit of learners, and who can act as stewards of this infrastructure,” says Philipp Schmidt, director of learning innovation at the MIT Media Lab. 

“Our shared vision is one where academic achievements, and the corresponding credentials that verify them, can open up new pathways for individuals to become who they want to be in the future,” says José Escamilla, director of TecLabs Learning Reimagined at Tecnologico de Monterrey.

To learn more about this project, visit digitalcredentials.mit.edu.

Forums address MIT’s plans to reshape its computer science education

Tue, 04/23/2019 - 10:02am

Community forums held last week for the MIT Stephen A. Schwarzman College of Computing working groups addressed how new ideas for its curriculum, research, infrastructure, and operations can best serve the community and society.

In February, MIT charged five working groups with generating ideas for the structure and operation of the new college. The groups are: Academic Degrees, Social Implications and Responsibilities of Computing, Organizational Structure, Faculty Appointments, and Computing Infrastructure. The groups each have two co-chairs and anywhere from about a dozen to more than 20 other members, representing many departments, labs, and centers across the Institute. The groups meet regularly, and will soon submit a report to MIT administration that outlines many potential ideas for their respective assignments.

To keep the community updated, three forums for all five working groups were held Wednesday, April 17, and Thursday, April 18. Co-chairs and members for each group delivered brief presentations on their group’s goals, information-gathering processes, current ideas, lessons learned, challenges, and questions left unanswered. Then, they opened the floor to questions and comments from the audience, which comprised dozens of students, faculty, and staff from across MIT.

In Wednesday morning’s forum, held in the Kresge Small Auditorium, Social Implications and Responsibilities of Computing co-chair Julie Shah shared a sentiment echoed by all working group presenters: The new college presents an opportunity to rethink how computer science is taught and researched at MIT and beyond.

“There is a sense we have a unique opportunity here in designing something across the educational curriculum, and also thinking about how we engage external parties — producers of technologies, consumers, and regulators,” said Shah, an associate professor of aeronautics and astronautics. “And what we do here can potentially be a model that lifts all of us that are working in the space across the country, and farther, together.”

All-inclusive computing

While the forums addressed a broad range of topics, common threads included: bringing all of MIT’s disciplines — including the humanities and social sciences — into the fold, lowering various barriers for computing, injecting ethics into research and coursework, and providing adequate computing resources for all.

In her presentation, Social Implications and Responsibilities co-chair Melissa Nobles said her group is considering new curricula for the 21st century that loop in ethical, social, and policy analyses. Their research shows current coursework isn’t necessarily optimal in that regard. She noted a need for investments of time and money to design new curricula.

“Certain classes do offer some discussion of ethics, but we think not nearly as robust … and certainly not as widespread as it will need to be,” said Nobles, who is the Kenan Sahin Dean and professor of political science in the School of Humanities, Arts, and Social Sciences. “We want students to think about their own particular role in [ethics] as creators of technologies … but also recognizing that we live within a larger economic, political, and social context. … I think the general idea is that it’s [about] individual behavior [and] the consequences of what we do.”

So far, a challenge for Academic Degrees, said co-chair Srini Devadas in the same forum, has been introducing computing to all MIT departments, especially the humanities and social sciences. The group, for instance, has looked into making MIT’s computer science minor more flexible for a greater diversity of students, and discussed possibilities for various computing graduate certificates. “We want to teach ground-breaking concepts, but I think it’s going to be a challenge [to serve] the entirety of the community of people interested in being in the computation core area or using it in their major discipline,” Devadas said. “This has to be as far away from a silo as we can possibly make it.”

In a similar vein, in Wednesday afternoon’s forum, also held in Kresge’s Small Auditorium, Organizational Structure co-chair Asu Ozdaglar said her group’s key goals right now are: ensuring the college nurtures interdisciplinary research, promoting computing across the MIT curriculum, and thoroughly integrating social sciences and humanities in with computing.

The group is also discussing the particularly challenging split affiliations in the Department of Electrical Engineering and Computer Science (EECS). “We have a spectrum of research, where it’s difficult to say where electrical engineering ends and computer science starts,” said Ozdaglar, the School of Engineering Distinguished Professor of Engineering and head of EECS. “We’re trying to figure out what design option [works best].”

In his presentation, Faculty Appointments co-chair Eran Ben-Joseph, head of the Department of Urban Studies and Planning, said one of the group’s guiding principles is attracting diverse faculty to create “an interdisciplinary hub to bring together unique faculty [and attracting] faculty that are different, and doing things that are nonconventional.”

One potential idea is hiring faculty in “clusters” across, say, science, engineering, and humanities that would teach and research a certain preselected topic that spans different disciplines. The idea is to “find a set of people who work collectively across boundaries and make them a group, and not just individuals working alone,” said group member Isaac Chuang, a professor of electrical engineering and a professor of physics.

Thursday morning’s forum, held on the sixth floor of the Samberg Center, saw Computing Infrastructure discuss best practices in hosting servers, storing and sharing tons of data, and cloud computing, among other factors. So far, the group has found broad support for creating a centralized network that provides “infinite” computing resources to everyone on campus. “[That] lowers the barrier of entry to places not necessarily involved in computing … and people that don’t particularly have access” to computing, said group co-chair Benoit Forget, an associate professor of nuclear science and engineering.

A major challenge, on the other hand, has been in setting up a system to ensure open-access data while navigating privacy, access, and licensing. In fact, a few audience members from different areas of MIT — including from the MIT Sloan School of Management, the Comparative Media Studies/Writing program, and the McGovern Institute for Brain Research at MIT — voiced concerns about the expenses and restrictions in accessing certain datasets for research. Currently, the working group is considering options for an Institute-wide data licensing and privacy framework that can address those issues.

Remaining open and dynamic

In addressing what will be in the working group reports, Shah drove home the point that the groups won’t propose specific recommendations, but instead will detail many different ideas to choose from and modify.

“Early in this process, it’s important for us to … think openly and understand the pros and cons of different approaches, so we can design a system that works well across all of MIT,” she said. Once groups submit reports, she added, there will be further discussions with the community: “This is not the end of input from you as a community — it’s the beginning.”

One notable question came from an audience member in Wednesday afternoon’s forum: After so much work, what if you get it wrong? The present co-chairs agreed that, while they hope to get many things right, there will always be room for improvement. Especially because the field of computer science so rapidly changes, the working groups must remain adaptable to fluctuations in academics and research, said Nelson Repenning, co-chair of Organizational Structure.

“Even if we do get it right now, the world’s going to change pretty quickly, and we are going to have to update [the structure and organization],” said Repenning, the associate dean of leadership and special projects and the Distinguished Professor of System Dynamics and Organization Studies at the MIT Sloan School of Management. “An element of dynamism to this is absolutely essential.”

David Autor awarded Carnegie fellowship

Mon, 04/22/2019 - 11:59pm

MIT economist David Autor has been named to the 2019 class of Andrew Carnegie Fellows, a high-profile honor for scholars pursuing research in the social sciences and humanities.

The fellowship is provided by the Carnegie Corporation of New York, which announced its newest set of honorees this morning. This year, 32 Carnegie fellowship recipients were selected from more than 300 applicants. The winners receive up to $200,000 to support a research sabbatical.

Autor, the Ford Professor of Economics at MIT, told MIT News he was “honored” simply to have been nominated for the fellowship. He called the news of the award itself “awesome” and said it would give him “a huge boost of confidence” for a new research project he is undertaking about shifting demographics, the growing urban-rural split in the contemporary economy, and the political implications of these changes.

During his year as a Carnegie fellow, Autor will be working on a project he calls “Depopulism: How the Inversion of the Rural-Urban Age Gradient Shapes the Diverging Economic and Political Geography of the U.S. and other Industrialized Countries.” It is well-known that the average age in many industrial Western countries has risen in the last several decades; however, little attention has been paid to the geography of this phenomenon.

In 1950, Autor notes, “low-density towns and rural areas were demographically among the youngest places in the country, while dense urban areas were among the oldest.” But over time, and especially after 1980, he adds, “population density reversed sign,” as the populations of lower-density towns and rural areas aged rapidly, while urban populations did not.

“These stark differential shifts in age structures augur substantial but largely unrecognized consequences for the distribution of prosperity across people and places, the relative dynamism or stasis of cities and towns, and the political divides between urban and nonurban voters,” Autor says.

While looking at the demographic and economic dynamics behind this trend in the U.S., Autor will also examine the demographics of other industrialized countries and analyze the relationship between economic geography, inequality, and political polarization.

Autor has been a member of the MIT faculty since 1999. He has developed a broad portfolio of research in labor economics, including studies about the polarization of the U.S. job market, the effects of global trade on jobs and economic geography, the impact of jobs programs and other interventions on workers, the U.S. disability insurance system, and the effects of automation on work.

Other MIT faculty who have received the Carnegie fellowship in recent years include economist Daron Acemoglu and political scientists Taylor Fravel, Richard Nielsen, and Charles Stewart.

Three from MIT awarded 2019 Guggenheim Fellowships

Mon, 04/22/2019 - 5:10pm

Three MIT faculty members are among 168 people out of 3,000 applicants granted a fellowship by the John Simon Guggenheim Memorial Foundation. The foundation's announcement notes that the awardees were chosen based on their prior accomplishments and strong future potential. The MIT recipients are David Jerison and Hong Liu in the School of Science, and Seth Mnookin in the School of Humanities, Arts, and Social Sciences.

“It’s exceptionally satisfying to name 168 new Guggenheim Fellows,” says Edward Hirsch, president of the Guggenheim Foundation. “These artists and writers, scholars and scientists, represent the best of the best.” This year’s recipients join more than 18,000 extraordinary individuals who previously received this honor.

David Jerison, a professor in the Department of Mathematics, has received a Guggenheim fellowship to study interfaces that divide regions in optimal ways; these can be applied to situations where minimized energy or cost is important. Previously, he was one of 10 principal investigators awarded a 2018 Simons Foundation Collaboration Grant. He is also a recipient of a Sloan Foundation Research Fellowship, the Bergman Prize, and a National Science Foundation Presidential Young Investigator Award. He is also currently a fellow of the American Academy of Arts and Sciences and the American Mathematical Society, and vice president of the American Mathematical Society. A dedicated teacher, Jerison became an MIT MacVicar Faculty Fellow in 2004 and has designed many popular courses for MIT’s Open Courseware, MITx and edX.

Hong Liu will be applying his fellowship to his interdisciplinary research on black holes, turbulence, and quantum many-body systems. A professor in the Department of Physics, Liu has helped found interconnections between gravitational, nuclear and condensed matter physics, one of the first to use string theory to study quark-gluon plasma and identify similarities between black holes and superconductors. Prior to this fellowship, he was elected an Alfred Sloan Fellow, an Outstanding Junior Investigator by the Department of Energy, and a Simons Fellow.

Seth Mnookin is the director of the Graduate Program in Science Writing and a professor in the Comparative Media Studies/Writing program. He has authored three books to date: his first was recognized as Best Book of the Year by The Washington Post, his second reached The New York Times' bestseller list, and the most recent won the “Science in Society Award” from the National Association of Science Writers. The Guggenheim Fellowship is the most recent award for Mnookin, whose other accolades include the American Medical Writers Association prize for best story of 2014 and his election to the board of the National Association of Science Writers.

Letter regarding MIT's upcoming climate change symposia

Mon, 04/22/2019 - 5:00pm

The following letter was sent to the MIT community on April 23 by President L. Rafael Reif

To the members of the MIT community,

Starting next fall and ending on the 50th anniversary of Earth Day – a year from today – MIT will hold a series of six campus symposia on the urgent challenges of climate change and climate action.

I write now to encourage you to save the date for as many of these conversations as you can.

Closer to the time, we will find a number of ways, including via the climate symposia website, to share the exact campus locations and the speakers. For now, the topics, dates and times:

Progress in Climate Science
October 2, 2019, 1–4 p.m.

The Climate Policy Problem
October 29, 2019, 4–7 p.m.

Decarbonizing the Electricity Sector
December 4, 2019, 3–6 p.m.

Economy-wide Deep Decarbonization – Beyond Electricity!
February 25, 2020, 5–8 p.m.

MIT Initiatives and the Role of Research Universities
April 2, 2020, 2–5 p.m.

Summing Up: “Why are we waiting?"
April 22, 2020, 1–4 p.m.

For the energy and imagination it took to develop this important series, I am deeply grateful to the faculty members who agreed to serve on the MIT Climate Action Symposia Organizing Committee; their names appear below. With the leadership of chair Paul Joskow, Professor Emeritus in economics, the committee gathered ideas for topics and speakers from across the MIT community and used that thoughtful input to shape a compelling series of conversations.

I hope these symposia will deepen our shared knowledge about current climate science and policy, and help inspire us all to find new and more effective ways to achieve the immediate and sustained action it will take to confront this civilizational threat.

I look forward to seeing many of you at the inaugural symposium on October 2.

Sincerely,

L. Rafael Reif

MIT Climate Action Symposia Organizing Committee

John M. Deutch

Kerry A. Emanuel

Paula T. Hammond

Colette L. Heald

Joi Ito

Paul L. Joskow, chair

Ernest J. Moniz

Richard Schmalensee

Evelyn N. Wang

Maria T. Zuber (ex officio)

Candid conversation about race

Mon, 04/22/2019 - 3:36pm

Candid discussions about race relations are vital at a time of “pushback” against social diversity in the U.S., said Beverly Daniel Tatum, the former president of Spelman College, in a talk at MIT on Thursday.

“It seems to me pretty clear we’re living in a pushback moment,” Tatum said, referring to resistance against both political progress by blacks and a diversifying population. She added: “I think that today, most people would agree, we are more polarized than ever.”

And while Tatum emphasized that there is no easy remedy for the long-running conditions of material inequality in the U.S., she suggested that a frank discussion of race relations could help pave the way for improved policies, noting that progress was needed in areas such as criminal justice reform, voting rights, housing policy, and more.

“The only way to interrupt the process is to be active,” Tatum said, speaking before an audience of over 250 people in MIT’s Wong Auditorium. “If we wait for perfection, we will never start.”

Tatum is the author of the 1997 bestseller, “Why Are All the Black Kids Sitting Together in the Cafeteria?” Recently updated in a 20th-anniversary edition, the book is the spring 2019 selection for MIT Reads, a campus-wide initiative in which community members read and discuss the same works.

Being taught to not talk

Tatum was introduced at the event by Melissa Nobles, the Kenan Sahin Dean of the School of MIT’s Humanities, Arts, and Social Sciences at MIT, and a professor of political science. Nobles praised Tatum’s “visionary leadership” at Spelman and served as an interlocutor for Tatum during the public discussion.

“There’s one key question that’s motivating this conversation this afternoon,” Nobles said. “Which is: Where are we, as a country, in having honest conversations about race and racism?”

In Tatum’s view, society is not producing as many of these conversations as it should. To demonstrate, she asked audience members to think about the first time they remember becoming aware of perceived racial differences — which, for most people in the crowd, happened before they were 10. Tatum then asked if people had, at the time, discussed the subject with adults. Few of them had.

“We learn early not to talk about race, and certainly not to talk about racism,” Tatum observed. “And you can’t solve a problem if you can’t talk about it.”

When we do discuss race, Tatum noted, those conversations can quickly become derailed by accusations and defensiveness — particularly when people try to determine if other individuals are “racist.”

Instead, Tatum suggested an alternate description of the subject. We all have some prejudices, but the term “racism” is better left to descriptions of society-wide, institutional advantages built on a foundation of perceived ethnic difference.

“Racially-based prejudice is not the same as racism,” Tatum said. “Racism is a system.”

And, as she elaborated, “If someone says to you, ‘You are racist,’ usually the person hearing that feels like they’ve been insulted in some significant way.” As a result, Tatum said, “I find no usefulness in trying to figure out, should this person be labelled a racist, or should that person be labelled a racist? My question is: Is that person, or is any person, working to interrupt the cycle of racism?”

Politics: What is possible?

A significant portion of Thursday’s conversation also focused on the rocky political path toward racial equality in modern America. Even in recent decades, Tatum said, we have seen moments of progress, as well as times of regression.

Tatum recalled speaking at a 1997 event with then-president Bill Clinton — himself a reader of “Why Are All the Black Kids Sitting Together in the Cafeteria?” — who suggested that the political moment was promising for race relations and new policy.

“We’re a nation at peace and we’re experiencing prosperity,” Tatum recalled Clinton saying.

However, as she pointed out, the Clinton presidency soon became sidetracked due to scandal. Before long, the terrorist attacks of September 11, 2001, meant the U.S. was no longer at peace; the economic recession of 2007-2008 then reduced the country’s prosperity.

The 2008 election of Barack Obama to the presidency represented a great advance in race relations — but also lessened the sense, among some people, that more progress was needed.

“Something happened when he was elected,” Tatum said. “And that was — victory was declared.” People began proclaiming that the U.S. has entered a “postracial” era, Tatum said, although, “Of course it became very clear during his tenure that we’re not postracial.”

Changing demographics in the U.S. have also contributed to racial unease, Tatum suggested. In 1954, the year of the Supreme Court’s landmark Brown v. Board of Education of Topeka ruling on school integration, the U.S. was ethnically about 90 percent white. As of the last census, the country was about 67 percent white, and among people age 21 and under, that figure drops to 52 percent.

“A lot of the rhetoric I think that we hear, particularly the anti-immigration rhetoric, I think is fueled by white response to that shrinking [number],” Tatum said. “Some people are disturbed by that.” Moreover, she added, “When a lot of things are changing, people feel stressed, and when they feel stressed, they tend to turn inward and get defensive, unless they’re being encouraged to be expansive. This is why leadership matters.”

What can be done?

In a question-and-answer session with the audience, Tatum responded to a variety of queries about what sorts of action could help limit structurally inequalities in a nation withover 300 million people and fractured federal politics.

“You have to think globally, and then … act locally,” Tatum said, referring to a popular environmental idea. “What’s happening in your local space that needs your attention?” At some times in the past, she aded, “Grassroots, person-to-person engagement has been shown to be the best strategy.”

Asked about the effects of social media on racial dialogues, Tatum said she was still optimistic that people can build new relationships, despite the potential for media to reinforce existing social and ideological differences.   

“Certainly social media is a challenge,” Tatum said. “To the extent that we can put our phones down and talk face to face, in the communities where we are, I encourage that. … I think that it requires more imagination perhaps than we have right at this moment, but I think it is possible to build connections.”

In university settings, she noted, structured community dialogues that unfold over time have proven successful at initiating and sustaining productive dialogues about racial relations and policies. But much like taking an antibiotic, she said, it is important to stick with such programs for their entire schedule, rather than stopping too soon. 

“There’s kind of an arc of discomfort,” Tatum said. “When you first start these conversations, they do feel awkward. And if you stop because you felt awkward, you never get to the place where you can do it well. … Yes, people make mistakes, yes, they say things that offend each other. And they come back the next week and try harder the next time. I mean, it’s a learning process, and we all have to be willing to learn.”

Tatum served from 2002 through 2015 as the ninth president of Spelman College, the historically black liberal arts college for women in Atlanta. She is now president emerita at Spelman.

A clinical psychologist by training, Tatum is also a former acting president of Mount Holyoke College, where she was a professor of psychology and education, and dean of the college and vice president for student affairs. Earlier in her career, Tatum was a faculty member at Westfield State College in Massachusetts and a lecturer at the University of California at Santa Barbara. She earned her BA at Wesleyan University and her MA and PhD in clinical psychology from the University of Michigan, as well as an MA in religious studies from Hartford Seminary.

MIT is hosting a follow-up discussion about “Why Are All the Black Kids Sitting Together in the Cafeteria?” on Wednesday, April 24, as part of the MIT Reads program, which is run by the MIT Libraries.

“We believe that can lead to greater understanding about topics and lead to a better and more cohesive community here at MIT,” said Chris Burgh, director of libraries at MIT, in introductory remarks at Thursday’s event.

The event was also organized by Kwadwo Poku, manager of diversity recruitment and initiatives in MIT’s School of Architecture and Planning, who spoke at the close of the session, quoting the American writer James Baldwin: “Not everything that is faced can be changed. But nothing can be changed until it is faced.”

The event was presented in partnership with the Institute Community and Equity Office; the MIT Alumni Association; the MIT Coop; MIT Human Resources; MIT Medical; the MIT Press; the Office of Engineering Outreach Programs; the Office of Minority Education; the Office of Multicultural Programs; the Office of Resource Development; the Office of the Vice Chancellor; the Office of Graduate Education; the School of Architecture and Planning; the School of Science; the Student Life Office and Human Resources, Sloan School of Management; the Title IX and Bias Response Office; the Program in Media Arts and Sciences, Media Lab; and the Program in Women’s and Gender Studies.

Working out makes hydrogels perform more like muscle

Mon, 04/22/2019 - 3:00pm

Human skeletal muscles have a unique combination of properties that materials researchers seek for their own creations. They’re strong, soft, full of water, and resistant to fatigue. A new study by MIT researchers has found one way to give synthetic hydrogels this total package of characteristics: putting them through a vigorous workout.

In particular, the scientists mechanically trained the hydrogels by stretching them in a water bath. And just as with skeletal muscles, the reps at the “gym” paid off. The training aligned nanofibers inside the hydrogels to produce a strong, soft, and hydrated material that resists breakdown or fatigue over thousands of repetitive movements.

The polyvinyl alcohol (PVA) hydrogels trained in the experiment are well-known biomaterials that researchers use for medical implants, drug coatings, and other applications, says Xuanhe Zhao, an associate professor of mechanical engineering at MIT. “But one with these four important properties has not been designed or manufactured until now.”

In their paper, published this week in the Proceedings of the National Academy of Sciences, Zhao and his colleagues describe how the hydrogels also can be 3-D-printed into a variety of shapes that can be trained to develop the suite of muscle-like properties.

In the future, the materials might be used in implants such as “heart valves, cartilage replacements, and spinal disks, as well as in engineering applications such as soft robots,” Zhao says.

Other MIT authors on the paper include graduate student Shaoting Lin, postdoc Ji Liu, and graduate student Xunyue Liu in Zhao’s lab.

Training for strength and more

Excellent load-bearing natural tissues such as muscles and heart valves are a bioinspiration to materials researchers, but it has been very challenging to design materials that capture all their properties simultaneously, Zhao says.

For instance, one can design a hydrogel with highly aligned fibers to give it strength, but it may not be as flexible as a muscle, or it may not have the water content that makes it compatible for use in humans. “Most of the tissues in the human body contain about 70 percent water, so if we want to implant a biomaterial in the body, a higher water content is more desirable for many applications in the body,” Zhao explains.

The discovery that mechanical training could produce a muscle-like hydrogel was something of an accident, says Lin, the lead author of the PNAS study. The research team had been performing cyclic mechanical loading tests on the hydrogels, trying to find the fatigue point where the hydrogels would begin to break down. They were surprised instead to find that the cyclic training was actually strengthening the hydrogels.

“The phenomenon of strengthening in hydrogels after cyclic loading is counterintuitive to the current understanding on fatigue fracture in hydrogels, but shares the similarity with the mechanism of muscle strengthening after training,” says Lin.

Before training, the nanofibers that make up the hydrogel are randomly oriented. “During the training process, what we realized is that we were aligning the nanofibers,” says Lin, adding that the alignment is similar to what happens to a human muscle under repeated exercise. This training made the hydrogels stronger and fatigue-resistant. The combination of the four key properties appeared after about 1,000 stretching cycles, but some of the hydrogels were stretched over 30,000 cycles without breaking down. The tensile strength of the trained hydrogel, in the direction of the aligned fibers, increased by about 4.3 times over the unstretched hydrogel.

At the same time, the hydrogel demonstrated soft flexibility, and maintained a high water content of 84 percent, the researchers found.

The antifatigue factor

The scientists turned to confocal microscopy to take a closer look at the trained hydrogels, to see if they could discover the reasons behind their impressive anti-fatigue property. “We put these through thousands of cycles of load, so why doesn’t it fail?” Lin says. “What we did is make a cut perpendicular to these nanofibers and tried to propagate a crack or damage in this material.”

“We dyed the fibers under the microscope to see how they deformed as a result of the cut, [and found that] a phenomenon called crack pinning was responsible for fatigue resistance,” Ji says.

“In an amorphous hydrogel, where the polymer chains are randomly aligned, it doesn’t take too much energy for damage to spread through the gel,” Lin adds. “But in the aligned fibers of the hydrogel, a crack perpendicular to the fibers is ‘pinned’ in place and prevented from lengthening because it takes much more energy to fracture through the aligned fibers one by one.”

In fact, the trained hydrogels break a famous fatigue threshold, predicted by the Lake-Thomas theory, which proposes the energy required to fracture a single layer of amorphous polymer chains such as those that make up PVA hydrogels. The trained hydrogels are 10 to 100 times more fatigue-resistant than predicted by the theory, Zhao and his colleagues concluded.

The research was supported, in part, by the National Science Foundation, the Office of Naval Research, and the U.S. Army Research Office through the Institute for Soldier Nanotechnologies at MIT.

Breakthrough in boiling

Mon, 04/22/2019 - 1:55pm

Engineers must manage a maelstrom in the core of operating nuclear reactors. Nuclear reactions deposit an extraordinary amount of heat in the fuel rods, setting off a frenzy of boiling, bubbling, and evaporation in surrounding fluid. From this churning flow, operators harness the removal of heat.

In search of greater efficiencies in nuclear systems, scientists have long sought to characterize and predict the physics underlying these processes of heat transfer, with only modest success.

But now a research team led by Emilio Baglietto, an associate professor of nuclear science and engineering at MIT, has made a significant breakthrough in detailing these physical phenomena. Their approach utilizes a modeling technology called computational fluid dynamics (CFD). Baglietto has developed new CFD tools that capture the fundamental physics of boiling, making it possible to track rapidly evolving heat transfer phenomena at the microscale in a range of different reactors, and for different operating conditions.

“Our research opens up the prospect of advancing the efficiency of current nuclear power systems and designing better fuel for future reactor systems,” says Baglietto.

The group, which includes Etienne Demarly, a doctoral candidate in nuclear science and engineering, and Ravikishore Kommajosyula, a doctoral candidate in mechanical engineering and computation, describes its work in the March 11 issue of Applied Physics Letters.

Baglietto, who arrived at MIT in 2011, is thermal hydraulics lead for the Consortium for Advanced Simulation of Lightwater Reactors (CASL), an initiative begun in 2010 to design predictive modeling tools to improve current and next generation reactors, and to ensure the economic viability of nuclear energy as an electricity source.

Central to Baglietto’s CASL work has been the issue of critical heat flux (CHF), which “represents one of the grand challenges for the heat transfer community,” he says. CHF describes a condition of boiling where there is a sudden loss of contact between the bubbling liquid, and the heating element, which in the case of the nuclear industry is the nuclear fuel rod. This instability can emerge suddenly, in response to changes in power levels, for example. As boiling reaches a crisis, a vaporous film covers the fuel surface, which then gives way to dry spots that quickly reach very high temperatures.

“You want bubbles forming and departing from the surface, and water evaporating, in order to take away heat,” explains Baglietto. “If it becomes impossible to remove the heat, it is possible for the metal cladding to fail.”

Nuclear regulators have established power settings in the commercial reactor fleet whose upper limits are well beneath levels that might trigger CHF. This has meant running reactors below their potential energy output.

“We want to allow as much boiling as possible without reaching CHF,” says Baglietto. “If we could know how far we are at all times from CHF, we could operate just on the other side, and improve the performance of reactors.”

Achieving this, says Baglietto, requires better modeling of the processes leading to CHF. “Previous models were based on clever guesses, because it was impossible to see what was actually going on at the surface where boiling took place, and because models didn’t take into account all the physics driving CHF,” says Baglietto.

So he set out to create a comprehensive, high-fidelity representation of boiling heat transfer processes up to the point of CHF. This meant creating physically accurate models of the movement of bubbles, boiling, and condensation taking place at what engineers call "the wall" — the cladding of four meter-tall, one centimeter-wide nuclear fuel rods, which are packed by the tens of thousands in a typical nuclear reactor core and surrounded by hot fluid.

While some of Baglietto’s computational models took advantage of existing knowledge of the complex fuel assembly heat transfer processes inside reactors, he also sought new experimental data to validate his models. He enlisted the help of department colleagues Matteo Bucci, the Norman C. Rasmussen Assistant Professor of Nuclear Science and Engineering, and Jacopo Buongiorno, the TEPCO Professor and associate department head for nuclear science and engineering.

Using electrically simulated heaters with surrogate fuel assemblies and transparent walls, MIT researchers were able to observe the fine details in the evolution of boiling to CHF.

“You’d go from a situation where nice little bubbles removed a lot of heat, and new water re-flooded the surface, keeping things cold, to an instant later when suddenly there was no more space for bubbles and dry spots would form and grow,” says Baglietto.

One fundamental corroboration emerged from these experiments. Baglietto’s initial models, contrary to conventional thinking, had suggested that during boiling, evaporation is not the exclusive form of heat removal. Simulation data showed that bubbles sliding, jostling and departing from the surface removed even more heat than evaporation, and experiments validated the findings of the models.

“Baglietto’s work represents a landmark in the evolution of predictive capabilities for boiling systems, enabling us to model behaviors at a much more fundamental level than ever possible before,” says W. David Pointer, group leader of advanced reactor engineering at the Oak Ridge National Laboratory, who was not involved in the research. “This research will allow us to develop significantly more aggressive designs that better optimize the power produced by fuel without compromising on safety, and it will have an immediate impact on performance in the current fleet as well as on next-generation reactor design.”

Baglietto’s research will also quickly improve the process for developing nuclear fuels. Instead of spending many months and millions of dollars on experiments, says Pointer, “We can shortcut those long sequences of tests by providing accurate, reliable models.”

In coming years, Baglietto’s comprehensive approach may help deliver fuel cladding that is more resistant to fouling and impurities, more accident tolerant, and that encourages higher wettability, making surfaces more conducive to contact with water and less likely to form dry spots. 

Even small improvements in nuclear energy output can make a big difference, Baglietto says.

“If fuel performs five percent better in an existing reactor, that means five percent more energy output, which can mean burning less gas and coal,” he says. “I hope to see our work very soon in U.S. reactors, because if we can produce more nuclear energy cheaply, reactors will remain competitive against other fuels, and make a greater impact on CO2 emissions."

The research was supported by the Department of Energy’s Consortium for Advanced Simulation of Light Water Reactors.

In it together: Faculty mentors and graduate students

Mon, 04/22/2019 - 1:00pm

It can be very easy for students to become overwhelmed in graduate school. The daily challenges of research, the pressure to reach academic milestones, and the management of life outside MIT can tax even the most well-organized mind. Although no student is alone in their cohort, reaching out to classmates or colleagues for help may be difficult exactly because everyone is likely experiencing the same struggles.

Faculty mentors, on the other hand, can offer graduate students authoritative beacons of hope. Understanding the rigors of graduate school, faculty mentors have the expertise and also the distance to provide perspective and to exemplify success after degree completion. Faculty mentors John Lienhard, Susan Murcott, Bradly Olsen, and Agustin Rayo have been honored by their students as "committed to caring" for affirming, inspiring, actively listening, and creating space for all students.

John Lienhard: Affirming students

Professor John Lienhard of the Department of Mechanical Engineering makes the members of his lab feel secure in their positions — and they are happier for it, according to his graduate students. In addition to fostering excellent advising practices, much of Lienhard’s research is “centered around those most in need,” specifically those vulnerable to water and food scarcity around the world.

The ability to demonstrate support and affirmation for his students has become a distinguishing feature of Lienhard’s success in mentoring. “Prof. Lienhard wrote me a kind email, gave me good comments for the things that were working well and encouraged me on the projects that were going behind schedule,” one student wrote. “His kindness helped me work harder and more effectively.”

When his students encounter an unforeseen obstacle, Lienhard offers perspective that encourages moving forward. “When I received a rejection notice from a journal,” one nominator wrote, “[Lienhard] took the time to reassure me that this happens … and that based on the reviewer’s comments, the value of the paper was still strong.”

Some of Lienhard’s students have developed their own excellent mentorship practices. “As a mentor of undergrads myself,” one nominator wrote, “I followed John's example in providing a warm and caring environment.” As a result, this nominator was honored with an Outstanding UROP Mentor Award.

Lienhard offers his students professional advice beyond academic research. “He gave me advice and encouragement in all of my endeavors,” one student noted, “whether or not they adhered to the traditional academic path.”

He practices informal advising (a Mentoring Guidepost identified by the Committed to Caring program). In group meetings, he initiates discussions with graduate students concerning many topics that extend beyond academia, including the importance of exercise, preparing for a career, and managing finances. Lienhard also emphasizes to his graduate students “the need to communicate ideas, through presentations and other interpersonal interactions.”

Susan Murcott: Inspiring learning and practice

Susan Murcott’s “passion, love, and dedication” to teaching and learning encourages her students not only to explore problems, but in their words, “carve our own path toward a solution.” A lecturer in MITs D-Lab, Murcott’s work contributes to the D-lab’s mission of designing and developing collaborative approaches and practical solutions to global poverty challenges.

Murcott not only wishes to attract students and collaborators from across disciplines, but also from outside of academia. She aims to build a diverse group of team members who offer a breadth of perspectives in other dimensions as well. “I am happiest when the composition of my team is multicultural, multi-generational, and of different ethnicities, genders, and disciplines,” she says.

After assembling her collaborators, Murcott says she tries to “cultivate a feeling in the classroom that we are a small community.” Students are encouraged to get to know one another personally so that they develop a sense of interest and belonging. Murcott prefers smaller classes so that she can get to know students individually and work with them on the “project-based, hands-on, action learning” that D-Lab is known for.

This community feeling creates a judgment-free space for students to express their ideas. Murcott models understanding and listening skills, and in the words of one nominator “always takes people’s ideas and input seriously, and with grace.” This welcoming classroom environment (another Mentoring Guidepost identified by the C2C Program) nurtures confidence in students and provides them with the power to learn and grow.

Although battling the world’s water issues can easily become an all-consuming task, Murcott supports her students’ work/life balance with sensitivity to their other obligations and by monitoring how much time a given class should require. “I try not to overload students with work,” she says. “I want students to have a balanced life.”

Murcott recommends that students seek out mentors on campus who are caring, and whose work is of particular interest. “Don’t waste time,” she says. Students should choose mentors who are mentally present, and get to know them well.

Bradley Olsen: Creating space for everyone

Associate professor of chemical engineering Bradley Olsen recognizes that balancing life in graduate school is difficult. He notes that faculty members and graduate students share the same basic stressors, such as home responsibilities, deaths in the family, health concerns, and, of course, a lot of work. Olsen says that seeing faculty members as “fallible human beings like everyone else” can make it easier for graduate students to relate, and even see their own challenges reflected back to them.

Olsen encourages his students to approach him if they have any issues with research, classes, or grad school life more broadly. Whether or not things are going well, he actively schedules meetings with his graduate students to check in (another Mentoring Guidepost). In one instance when Olsen knew a student needed more support, his efforts to initiate follow-up meetings were deeply appreciated.

In the Olsen lab, graduate students and post-docs participate in small focus groups where a number of important topics are discussed, including mental health, women in science, and gender climate. During a group meeting on sexual harassment, Olsen encouraged the group to come up with ways to make MIT more welcoming to individuals who are victimized. “He also defined for us sexual harassment and how to recognize it,” the student said. This discussion provided an opening for lab members to explore ways to stop sexual harassment in our workplace and community.

Describing his own advising style, Olsen admits, “I sincerely wish I had a system, something with a catchy book-like title, but it’s really controlled chaos.” Olsen does his best to fulfill others’ expectations as well as his own. Along the way, he tries to be completely transparent about how things are going, and to apologize when necessary. His goal is continuous improvement and learning. “We do not aspire to be perfect, but we should always strive to grow,” Olsen says.

Agustin Rayo: Actively listening

Professor of philosophy Agustin Rayo’s concern for the mental health of his students is a direct result of his experience in their shoes. Particularly as an international student, Rayo says, “graduate school was rough, especially the first couple of years.”

Being away from his home country of Mexico was difficult for Rayo, and he often felt that he was academically behind his peers. “I was so stressed that I developed insomnia, which made everything worse,” he remembers.

Finding resources on campus, including MIT Mental Health and Counseling, made all of the difference for him. “I was in therapy throughout graduate school,” Rayo shares. “I'm not sure I would have made it to graduation without that kind of support.”

Keeping these experiences in mind, Rayo is quick to respond to any sign of poor mental health among his students. One advisee comments of Rayo, “I couldn't ask for a faculty member to take mental health issues in students more seriously.”

Rayo promotes work/life balance, a key component of mental health (and a Mentoring Guidepost). “I don't think I had a very good work/life balance until I got married,” Rayo says. “We now have a toddler and he is very good at ensuring that I don't neglect the 'life' part of my life!” Although marriage isn’t the only way to achieve balance, Rayo feels that prioritizing relationships and activities outside of MIT is an important step in the right direction.

When considering the department as a whole, Rayo places a high value on climate. Responding to a perceived issue in the department involving gender norms, he immediately scheduled meetings with the involved parties to ensure that all were heard and that every concern was addressed. “He made it clear that he supported us and valued our input,” one student says, “and worked with us to resolve the situation.”

One nominator emphasizes how seriously Rayo takes his role as a mentor. “I've never encountered a more caring, compassionate faculty member who was so dedicated to students' personal and academic wellbeing.”

Making graduate education more empowering

The Committed to Caring (C2C) program is an initiative of the Office of Graduate Education and contributes to its mission of making graduate education at MIT “empowering, exciting, holistic, and transformative.”

C2C invites graduate students from across MIT’s campus to nominate professors whom they believe to be outstanding mentors. Selection criteria for the award include the scope and reach of advisor impact on the experience of graduate students, excellence in scholarship, and demonstrated commitment to diversity and inclusion.

By recognizing the human element of graduate education, C2C seeks to encourage excellent advising and mentorship across MIT’s campus. More information about these and other C2C honorees and their advising practices may be found on the Committed to Caring pages.

Designing water infrastructure for climate uncertainty

Mon, 04/22/2019 - 12:40pm

In Kenya’s second largest city, Mombasa, the demand for water is expected to double by 2035 to an estimated 300,000 cubic meters per day. In Mombasa’s current warm and humid climate, that water comes from a substantial volume of precipitation that may also change significantly as the region warms in the coming decades in line with global climate model projections.

What’s not clear from the projections, however, is whether precipitation levels will rise or fall along with that warming.

The ultimate direction and magnitude of precipitation change is a major concern for designers of a proposed dam and reservoir system that will capture runoff into the Mwache River, which currently totals about 310,000 cubic meters per day. The substantial uncertainty in future runoff makes it difficult to determine the reservoir capacity necessary to meet Mombasa’s water demand throughout its estimated 100-year lifetime. City planner are therefore faced with deciding whether to invest in an expensive, large-scale dam to provide a consistent water supply under the driest future climate projected by the models, a smaller-scale dam that could accommodate current needs, or start small and build capacity as needed.

To help cities like Mombasa sort through such consequential decisions, a team of researchers at the MIT Joint Program on the Science and Policy of Global Change has developed a new, systematic approach to designing long-term water infrastructure amid climate change uncertainty. Their planning framework assesses the potential to learn about regional climate change over time as new observations become available, and thus evaluate the suitability of flexible approaches that add water storage capacity incrementally if the climate becomes warmer and drier.

The researchers describe the framework and its application to Mombasa in the journal Nature Communications.

A new framework for water infrastructure design

Using the framework to compare the likely lifetime costs of a flexible approach with those of two static, irreversible options for the proposed dam in Mombasa — one designed for the driest, warmest climate, the other for today’s climate — the research team found the flexible approach to be the most cost-effective while still maintaining a reliable supply of water to Mombasa.

“We found that the flexible adaptive option, which allows for the dam’s height to be increased incrementally, substantially reduces the risk of overbuilding infrastructure that you don’t need, and maintains a similar level of water supply reliability in comparison to having a larger dam from the get-go,” says Sarah Fletcher, the study’s lead author, a postdoctoral fellow at MIT’s Department of Civil and Environmental Engineering.

Fletcher’s work on the study was largely completed as a PhD student at MIT’s Institute for Data, Systems and Society under the supervision of co-author and MIT Joint Program Research Scientist Kenneth Strzepek, and in collaboration with co-author and former Joint Program research associate Megan Lickley, now a PhD student in the Department of Earth, Atmospheric and Planetary Sciences.

The Kenyan government is now in the final stages of the design of the Mwache Dam.

“Due to the Joint Program’s efforts to make leading-edge climate research available for use globally, the results from this study have informed the ongoing design and master planning process,” says Strzepek. “It’s a perfect illustration of the mission of Global MIT: ‘Of the World. In the World. For the World.’”

By pinpointing opportunities to reliably apply flexible rather than static approaches to water infrastructure design, the new planning framework could free up billions of dollars in savings in climate adaptation investments — savings that could be passed on to provide water infrastructure solutions to many more resource-limited communities that face substantial climate risk.

Incorporating learning into large infrastructure decision-making

The study may be the first to address a limitation in current water infrastructure planning, which traditionally assumes that today’s climate change uncertainty estimates will persist throughout the whole planning timeline, one that typically spans multiple decades. In many cases this assumption causes flexible, adaptive planning options to appear less cost-effective than static approaches. By estimating upfront how much planners can expect to learn about climate change in the future, the new framework can enable decision-makers to evaluate whether adaptive approaches are likely to be reliable and cost effective.

"Climate models can provide us with a useful range of potential trajectories of the climate system,” says Lickley. “There is considerable uncertainty in terms of the magnitude and timing of these changes over the next 50 to 100 years. In this work we show how to incorporate learning into these large infrastructure decisions as we gain new knowledge about the climate trajectory over the coming decades."

Using this planning tool, a city planner could determine whether it makes sense to choose a static or flexible design approach for a proposed water infrastructure system based on current projections of maximum temperature and precipitation change over the lifetime of the system, along with information that will eventually come in from future observations of temperature and precipitation change. In the study, the researchers performed this analysis for the proposed Mombasa dam under thousands of future regional climate simulations covering a wide range of potential temperature and precipitation trends.

“For example, if you started off on a high-temperature trajectory and 40 years from now you remain on that trajectory, you would know that none of the low-temperature design options are feasible anymore,” says Fletcher. “At that point you would have exceeded a certain amount of warming, and could then rule out the low-temperature-change planning option, and take advantage of an adaptive approach to increase the capacity.”

Future development on the planning framework may incorporate analysis of the potential to learn about other sources of uncertainty, such as the growth in demand for water resources, during the lifetime of a water infrastructure project.

The study was supported by the MIT Abdul Latif Jameel Water and Food Systems Lab and National Science Foundation.

How slippery surfaces allow sticky pastes and gels to slide

Mon, 04/22/2019 - 12:32pm

An MIT research team that has already conquered the problem of getting ketchup out of its bottle has now tackled a new category of consumer and manufacturing woe: how to get much thicker materials to slide without sticking or deforming.

The slippery coatings the team has developed, called liquid-impregnated surfaces, could have numerous advantages, including eliminating production waste that results from material that sticks to the insides of processing equipment. They might also improve the quality of products ranging from bread to pharmaceuticals, and even improve the efficiency of flow batteries, a rapidly developing technology that could help to foster renewable energy by providing inexpensive storage for generated electricity.

These surfaces are based on principles initially developed to help foods, cosmetics, and other viscous liquids slide out of their containers, as devised by Kripa Varanasi, a professor of mechanical engineering at MIT, along with former students Leonid Rapoport PhD ’18 and Brian Solomon PhD ’16. The new work is described today in the journal ACS Applied Materials and Interfaces.

Like the earlier surfaces they developed, which led to the creation of a spinoff company called LiquiGlide, the new surfaces are based on a combination of a specially textured surface and a liquid lubricant that coats the surface and remains trapped in place through capillary action and other intermolecular forces associated with such interfaces. The new paper explains the fundamental design principles that can achieve almost 100 percent friction reduction for these gel-like fluids.

Needing a squeeze

Such materials, known as yield-stress fluids, including gels and pastes, are ubiquitous. They can be found in consumer products such as food, condiments, and cosmetics, and in products in the energy and pharmaceuticals industries. Unlike other fluids such as water and oils, these materials will not start to flow on their own, even when their container is turned upside down. Starting the flow requires an input of energy, such as squeezing the container.

But that squeezing has its own effects. For example, bread-making machinery typically includes scrapers that constantly push the sticky dough away from the sides of its container, but that constant scraping can result in over-kneading and a denser loaf. A slippery container that requires no scraping could thus produce better-tasting bread, Varanasi says. By using this system, “beyond getting everything out of the container, you now add higher quality” of the resulting product.

That may not be critical where bread is concerned, but it can have great impact on pharmaceuticals, he says. The use of mechanical scrapers to propel drug materials through mixing tanks and pipes can interfere with the effectiveness of the medicine, because the shear forces involved can damage the proteins and other active compounds in the drug.

By using the new coatings, in some cases it’s possible to achieve a 100 percent reduction in the drag the material experiences — equivalent to “infinite slip,” Varanasi says.

“Generally speaking surfaces are enablers,” says Rapoport. “Superhydrophobic surfaces, for example, enable water to roll easily, but not all fluids can roll. Our surfaces enable fluids to move by whichever way is more preferable for them — be it rolling or sliding. In addition we found that yield-stress fluids can move on our surfaces without shearing, essentially sliding like solid bodies. This is very important when you want to maintain the integrity of these materials when they are being processed.”

Like the earlier version of slippery surfaces Varanasi and his collaborators created, the new process begins by making a surface that is textured at the nanoscale, either by etching a series of closely spaced pillars or walls on the surface, or mechanically grinding grooves or pits. The resulting texture is designed to have such tiny features that capillary action — the same process that allows trees to draw water up to their highest branches through tiny openings beneath the bark — can act to hold a liquid, such as a lubricating oil, in place on the surface. As a result, any material inside a container with this kind of lining essentially only comes in contact with the lubricating liquid, and slides right off instead of sticking to the solid container wall.

When a yield stress fluid, a gel-like material, flows in a simple glass tube it gets stuck to the walls and experiences shear stress. However, a tube coated with a slippery coating allows the fluid to move as a plug without shearing and without smearing on the tube. Courtesy of the researchers.

The new work described in this paper details the principles the researchers came up with to enable the optimal selection of surface texturing, lubricating material, and manufacturing process for any specific application with its particular combination of materials.

Helping batteries to flow

Another important application for the new coatings is in a rapidly developing technology called flow batteries. In these batteries, solid electrodes are replaced by a slurry of tiny particles suspended in liquid, which has the advantage that the capacity of the battery can be increased at any time simply by adding bigger tanks. But the efficiency of such batteries can be limited by the flow rates.

Using the new slippery coatings could significantly boost the overall efficiency of such batteries, and Varanasi worked with MIT professors Gareth McKinley and Yet-Ming Chiang on developing such a system led by Solomon and Xinwei Chen, a former postdoc in Chiang’s lab.

These coatings could resolve a conundrum that flow battery designers have faced, because they needed to add carbon to the slurry material to improve its electrical conductivity, but the carbon also made the slurry much thicker and interfered with its movement, leading to “a flow battery that couldn’t flow,” Varanasi says.

“Previously flow batteries had a trade-off in that as you add more carbon particles the slurry becomes more conductive, but it also becomes thicker and much more challenging to flow,” says Solomon. “Using slippery surfaces lets us have the best of both worlds by allowing flow of thick, yield-stress slurries.”

The improved system allowed the use of a flow electrode formulation that resulted in a fourfold increase in capacity and an 86 percent savings in mechanical power, compared with the use of traditional surfaces. These results were described recently in the journal ACS Applied Energy Materials.

“Apart from fabricating a flow battery device which incorporates the slippery surfaces, we also laid out design criteria for their electrochemical, chemical, and thermodynamic stability,” explains Solomon. “Engineering surfaces for a flow battery opens up an entirely new branch of applications that can help meet future energy storage demand.”

The research was supported by the Joint Center for Energy Storage Research, an Energy Research Hub funded by the U.S. Department of Energy, and by the Martin Family Society of Fellows for Sustainability.

Isabelle de Courtivron Writing Prize announces winners for 2019

Mon, 04/22/2019 - 12:20pm

Global Studies and Languages announced this year's winners of the Isabelle de Courtivron writing prize, awarded annually to recognize high-quality undergraduate writing (creative or expository) on topics related to immigrant, diaspora, bicultural, bilingual, and/or mixed-race experiences. The prize was established to honor Distinguished Professor Emerita Isabelle de Courtivron on the occasion of her retirement in 2010.

Five undergraduates received awards: First Prize went to Ivy Li for “To See a Brief Future.” Second Place prizes were awarded to Hanna Kherzai for "Don’t Tell Them” and Chloe Yang for “Dear Asian Tourists of MIT.” Honorable Mentions were awarded to Angela Lin for "Lost in Translation” and Abdalla Osman for "Dear Brother."

The judges noted that every single one of this year’s entries was profoundly moving. The writers shared their and their families’ inner worlds, leading readers through their lived experiences in between worlds, cultures, and languages; experiences that played out in a wide array of spaces, from the intimacy of a living room or a phone conversation, to airports and temples, to MIT’s chaotic Infinite Corridor and career fair. It was most humbling to be let into these worlds, to be entrusted with these stories and with the writers’ vulnerability. The winning pieces span a variety of genres: poetry, drama, and creative non-fiction. Family is central in most of the entries.

The prize winners will be honored at the GSL Spring Fest April 22, along with other honorees. Read the prize-winning entries and learn more about the writers.

2019 Change-Makers honored for fighting sexual misconduct

Mon, 04/22/2019 - 11:30am

On April 10, members of the MIT community came together to recognize and celebrate the achievements of select students, student groups, faculty, and staff for being “Change-Makers” in their corners of MIT. Change-Makers are individuals or groups who combat sexual misconduct by challenging harmful attitudes, language, or behaviors in order to create a safer and more inclusive campus culture.

Hosted by the offices of Violence Prevention and Response (VPR) and Title IX and Bias Response (T9BR), the Change-Maker Awards Banquet is held against a backdrop of a number of campus-wide events marking April as Sexual Assault Awareness Month. Now in its third year, the banquet features awards in different categories, including: Outstanding Undergraduate Student, Outstanding Graduate Student, Outstanding Staff Member, Oustanding Group, and Outstanding Pleasure Peer Educator. VPR and T9BR added a new category this year — Outstanding Department/Lab/Center (DLC) — to recognize a DLC for actively working to bring about positive culture change and prevent sexual misconduct.

Chancellor Cynthia Barnhart SM ‘85, PhD ‘88 kicked off the 2019 celebration by recognizing the newest class of Change-Makers, and highlighting a number of campuswide prevention, education, and response efforts that are currently underway.

“In their own creative and impactful ways, this year’s class of Change-Makers are challenging harmful attitudes and behaviors, and are helping to bring about important changes in culture — changes that make it clear that sexual misconduct and harassment of any kind have absolutely no place at MIT,” says Barnhart. “And their education, prevention, and response work — whether it’s with other students, colleagues, or throughout entire departments — bolsters our campus-wide work.”

Barnhart went on to highlight the 2019 Association of American Universities Campus Climate Survey on Sexual Misconduct that is open to students through May 1, as well as new groups responsible for advancing recommendations from a recent National Academies of Sciences, Engineering, and Medicine report.

Nominated by faculty, staff, and students from across MIT, this year’s awardees demonstrated a passion for, and dedication to, addressing sexual violence in their communities. The Awards Committee, which is comprised of staff from VPR and T9BR, received a record number of nominations. Each recipient was selected for their creative approach, depth of contribution, and level of impact.

The 2019 Change-Makers are:

Outstanding Undergraduate Student: Senior Gabrielle Ballard, who studies humanities and engineering, was selected for her contributions as a student leader invested in advancing conversations around equity and inclusion inside and outside of the classroom. In her roles as co-chair for the Black Women’s Alliance, a Pleasure educator, a student assistant in the Women and Gender Studies office, and a member of the multicultural recruitment team for MIT Admissions, Ballard has consistently demonstrated a desire to create change, to advance social justice, and to use an intersectional approach to her work.

Outstanding Graduate Student: Fifth-year graduate student in the Department of Material Science and Engineering Sarah Goodman received the Change-Maker award for her activism and role in shaping local, state, and federal policy. Her efforts include working on the External Affairs Board of the Graduate Student Council to craft responses to the U.S. Department of Education’s proposed Title IX regulations and to give input on federal legislation pertaining to sexual violence in the sciences. Her commitment to advocating for policy change has galvanized graduate students at MIT to use their voices and platforms as well.

Outstanding Staff Member: Amanda Pickett, a program assistant in Career Advising and Professional Development, was recognized for her ability to “call people in rather than calling them out.” She has put on events focused on a variety of topics, including: addressing sexual violence, LBGTQ+ allyship, understanding privilege, and working to create a healthier and safer community. These events have all come from Pickett’s own enthusiasm for having conversations about difficult topics in ways that don’t feel alienating.

Outstanding Group: The Healthy Masculinities Club, founded by graduate student Jay Dev and now led by his fellow graduate students Zack Avre and David Robinson, is a space open to all genders, but composed primarily of male-identifying people. The group was honored for coming together to discuss how to address and challenge harmful attitudes, language, and behavior. Their regular workshops tackle topics including masculinity, boyhood, intersectionality, consent, and sexual violence. The group originated in the Department of Urban Studies and Planning but it is open to anyone in the MIT community.

Outstanding Department: The Department of Chemical Engineering, which is led by Professor Paula Hammond ‘84, PhD ‘93, was selected for the hard work its faculty and students have put in to better understand the academic climate and for launching initiatives to make the climate more inclusive and welcoming. The entire chemical engineering department has elected to participate in an Inclusive Environments workshop, similar to the ones held by the Department of Chemistry in 2018. This workshop is a collaborative effort between faculty and students. Students supported the creation of these workshops by helping VPR and T9BR tailor the content to the relevant experiences within the department. Their feedback and guidance proved instrumental to developing an interactive and engaging workshop for all lab groups. Additionally, graduate students created a Women in Chemical Engineering group to continue working on fostering a welcoming and inclusive environment for all identities in the department. These examples underscore how the department and its students have cared and initiated change together.

Outstanding Pleasure Educator: Senior Madiha Shafquat, who is studying biological engineering, has been a powerful and consistent member of Pleasure for two and a half years. She was awarded a Change-Maker award for spearheading several initiatives, including raising awareness about Pleasure in the broader community and seeking to boost the quality of life here at MIT. She has modeled self-care, boundary setting, mentorship, and collaboration for staff and students alike.

Neuroscientists reverse some behavioral symptoms of Williams Syndrome

Mon, 04/22/2019 - 10:59am

Williams Syndrome, a rare neurodevelopmental disorder that affects about 1 in 10,000 babies born in the United States, produces a range of symptoms including cognitive impairments, cardiovascular problems, and extreme friendliness, or hypersociability.

In a study of mice, MIT neuroscientists have garnered new insight into the molecular mechanisms that underlie this hypersociability. They found that loss of one of the genes linked to Williams Syndrome leads to a thinning of the fatty layer that insulates neurons and helps them conduct electrical signals in the brain.

The researchers also showed that they could reverse the symptoms by boosting production of this coating, known as myelin. This is significant, because while Williams Syndrome is rare, many other neurodevelopmental disorders and neurological conditions have been linked to myelination deficits, says Guoping Feng, the James W. and Patricia Poitras Professor of Neuroscience and a member of MIT’s McGovern Institute for Brain Research.

“The importance is not only for Williams Syndrome,” says Feng, who is one of the senior authors of the study. “In other neurodevelopmental disorders, especially in some of the autism spectrum disorders, this could be potentially a new direction to look into, not only the pathology but also potential treatments.”

Zhigang He, a professor of neurology and ophthalmology at Harvard Medical School, is also a senior author of the paper, which appears in the April 22 issue of Nature Neuroscience. Former MIT postdoc Boaz Barak, currently a principal investigator at Tel Aviv University in Israel, is the lead author and a senior author of the paper.

Impaired myelination

Williams Syndrome, which is caused by the loss of one of the two copies of a segment of chromosome 7, can produce learning impairments, especially for tasks that require visual and motor skills, such as solving a jigsaw puzzle. Some people with the disorder also exhibit poor concentration and hyperactivity, and they are more likely to experience phobias.

In this study, the researchers decided to focus on one of the 25 genes in that segment, known as Gtf2i. Based on studies of patients with a smaller subset of the genes deleted, scientists have linked the Gtf2i gene to the hypersociability seen in Williams Syndrome.

Working with a mouse model, the researchers devised a way to knock out the gene specifically from excitatory neurons in the forebrain, which includes the cortex, the hippocampus, and the amygdala (a region important for processing emotions). They found that these mice did show increased levels of social behavior, measured by how much time they spent interacting with other mice. The mice also showed deficits in fine motor skills and increased nonsocial related anxiety, which are also symptoms of Williams Syndrome.

Next, the researchers sequenced the messenger RNA from the cortex of the mice to see which genes were affected by loss of Gtf2i. Gtf2i encodes a transcription factor, so it controls the expression of many other genes. The researchers found that about 70 percent of the genes with significantly reduced expression levels were involved in the process of myelination.

“Myelin is the insulation layer that wraps the axons that extend from the cell bodies of neurons,” Barak says. “When they don’t have the right properties, it will lead to faster or slower electrical signal transduction, which affects the synchronicity of brain activity.”

Further studies revealed that the mice had only about half the normal number of mature oligodendrocytes — the brain cells that produce myelin. However, the number of oligodendrocyte precursor cells was normal, so the researchers suspect that the maturation and differentiation processes of these cells are somehow impaired when Gtf2i is missing in the neurons.

This was surprising because Gtf2i was not knocked out in oligodendrocytes or their precursors. Thus, knocking out the gene in neurons may somehow influence the maturation process of oligodendrocytes, the researchers suggest. It is still unknown how this interaction might work.

“That’s a question we are interested in, but we don’t know whether it’s a secreted factor, or another kind of signal or activity,” Feng says.

In addition, the researchers found that the myelin surrounding axons of the forebrain was significantly thinner than in normal mice. Furthermore, electrical signals were smaller, and took more time to cross the brain in mice with Gtf2i missing.

The study is an example of pioneering research into the contribution of glial cells, which include oligodendrocytes, to neuropsychiatric disorders, says Doug Fields, chief of the nervous system development and plasticity section of the Eunice Kennedy Shriver National Institute of Child Health and Human Development.

“Traditionally myelin was only considered in the context of diseases that destroy myelin, such as multiple sclerosis, which prevents transmission of neural impulses. More recently it has become apparent that more subtle defects in myelin can impair neural circuit function, by causing delays in communication between neurons,” says Fields, who was not involved in the research.

Symptom reversal

It remains to be discovered precisely how this reduction in myelination leads to hypersociability. The researchers suspect that the lack of myelin affects brain circuits that normally inhibit social behaviors, making the mice more eager to interact with others.  

“That’s probably the explanation, but exactly which circuits and how does it work, we still don’t know,” Feng says.

The researchers also found that they could reverse the symptoms by treating the mice with drugs that improve myelination. One of these drugs, an FDA-approved antihistamine called clemastine fumarate, is now in clinical trials to treat multiple sclerosis, which affects myelination of neurons in the brain and spinal cord. The researchers believe it would be worthwhile to test these drugs in Williams Syndrome patients because they found thinner myelin and reduced numbers of mature oligodendrocytes in brain samples from human subjects who had Williams Syndrome, compared to typical human brain samples.

“Mice are not humans, but the pathology is similar in this case, which means this could be translatable,” Feng says. “It could be that in these patients, if you improve their myelination early on, it could at least improve some of the conditions. That’s our hope.”

Such drugs would likely help mainly the social and fine-motor issues caused by Williams Syndrome, not the symptoms that are produced by deletion of other genes, the researchers say. They may also help treat other disorders, such as autism spectrum disorders, in which myelination is impaired in some cases, Feng says.

“We think this can be expanded into autism and other neurodevelopmental disorders. For these conditions, improved myelination may be a major factor in treatment,” he says. “We are now checking other animal models of neurodevelopmental disorders to see whether they have myelination defects, and whether improved myelination can improve some of the pathology of the defects.”

The research was funded by the Simons Foundation, the Poitras Center for Affective Disorders Research at MIT, the Stanley Center for Psychiatric Research at the Broad Institute of MIT and Harvard, and the Simons Center for the Social Brain at MIT.

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