Author: MIT News

MIT spinout seeks to transform food safety testing

by Andi Sutton | Abdul Latif Jameel Water and Food Systems Lab |

“This is a $10 billion market and everyone knows it.” Those are the words of Chris Hartshorn, CEO of a new MIT spinout — Xibus Systems — that is aiming to make a splash in the food industry with their new food safety sensor.

Hartshorn has considerable experience supporting innovation in agriculture and food technology. Prior to joining Xibus, he served as chief technology officer for Callaghan Innovation, a New Zealand government agency. A large portion of the country’s economy relies upon agriculture and food, so a significant portion of the innovation activity there is focused on those sectors.

While there, Hartshorn came in contact with a number of different food safety sensing technologies that were already on the market, aiming to meet the needs of New Zealand producers and others around the globe. Yet, “every time there was a pathogen-based food recall” he says, “it shone a light on the fact that this problem has not yet been solved.”

He saw innovators across the world trying to develop a better food pathogen sensor, but when Xibus Systems approached Hartshorn with an invitation to join as CEO, he saw something unique in their approach, and decided to accept.

Novel liquid particles provide quick indication of food contamination

Xibus Systems was formed in the fall of 2018 to bring a fast, easy, and affordable food safety sensing technology to food industry users and everyday consumers. The development of the technology, based on MIT research, was supported by two commercialization grants through the MIT Abdul Latif Jameel Water and Food Systems Lab’s J-WAFS Solutions program. It is based on specialized droplets — called Janus emulsions — that can be used to detect bacterial contamination in food. The use of Janus droplets to detect bacteria was developed by a research team led by Tim Swager, the John D. MacArthur Professor of Chemistry, and Alexander Klibanov, the Novartis Professor of Biological Engineering and Chemistry.

Swager and researchers in his lab originally developed the method for making Janus emulsions in 2015. Their idea was to create a synthetic particle that has the same dynamic qualities as the surface of living cells.

The liquid droplets consist of two hemispheres of equal size, one made of a blue-tinted fluorocarbon and one made of a red-tinted hydrocarbon. The hemispheres are of different densities, which affects how they align and how opaque or transparent they appear when viewed from different angles. They are, in effect, lenses. What makes these micro-lenses particularly unique, however, is their ability to bind to specific bacterial proteins. Their binding properties enabled them to move, flipping from a red hemisphere to blue based on the presence or absence of a particular bacteria, like Salmonella.

“We were thrilled by the design,” Swager says. “It is a completely new sensing method that could really transform the food safety sensing market. It showed faster results than anything currently available on the market, and could still be produced at very low cost.”

Janus emulsions respond exceptionally quickly to contaminants and provide quantifiable results that are visible to the naked eye or can be read via a smartphone sensor.

“The technology is rooted in very interesting science,” Hartshorn says. “What we are doing is marrying this scientific discovery to an engineered product that meets a genuine need and that consumers will actually adopt.”

Having already secured nearly $1 million in seed funding from a variety of sources, and also being accepted into Sprout, a highly respected agri-food accelerator, they are off to a fast start.

Solving a billion-dollar industry challenge

Why does speed matter? In the field of food safety testing, the standard practice is to culture food samples to see if harmful bacterial colonies form. This process can take many days, and often can only be performed offsite in a specialized lab.

While more rapid techniques exist, they are expensive and require specialized instruments — which are not widely available — and still typically require 24 hours or more from start to finish. In instances where there is a long delay between food sampling and contaminant detection, food products could have already reached consumers hands — and upset their stomachs. While the instances of illness and death that can occur from food-borne illness are alarming enough, there are other costs as well.  Food recalls result in tremendous waste, not only of the food products themselves but of the labor and resources involved in their growth, transportation, and processing. Food recalls also involve lost profit for the company. North America alone loses $5 billion annually in recalls, and that doesn’t count the indirect costs associated with the damage that occurs to particular brands, including market share losses that can last for years.

The food industry would benefit from a sensor that could provide fast and accurate readings of the presence and amount of bacterial contamination on-site. The Swager Group’s Janus emulsion technology has many of the elements required to meet this need and Xibus Systems is working to improve the speed, accuracy, and overall product design to ready the sensor for market.

Two other J-WAFS-funded researchers have helped improve the efficiency of early product designs. Mathias Kolle, assistant professor in the Department of Mechanical Engineering at MIT and recipient of a separate 2017 J-WAFS seed grant, is an expert on optical materials. In 2018, he and his graduate student Sara Nagelberg performed the calculations describing light’s interaction with the Janus particles so that Swager’s team could modify the design and improve performance. Kolle continues to be involved, serving with Swager on the technical advisory team for Xibus.

This effort was a new direction for the Swager group. Says Swager: “The technology we originally developed was completely unprecedented. At the time that we applied to for a J-WAFS Solutions grant, we were working in new territory and had minimal preliminary results. At that time, we would have not made it through, for example,  government funding reviews which can be conservative. J-WAFS sponsorship of our project at this early stage was critical to help us to achieve the technology innovations that serve as the foundation of this new startup.”

Xibus co-founder Kent Harvey — also a member of the original MIT research team—is joined by Matthias Oberli and Yuri Malinkevich. Together with Hartshorn they are working on a prototype for initial market entry. They are actually developing two different products: a smartphone sensor that is accessible to everyday consumers, and a portable handheld device that is more sensitive and would be suitable for industry. If they are able to build a successful platform that meets industry needs for affordability, accuracy, ease of use, and speed, they could apply that platform to any situation where a user would need to analyze organisms that live in water. This opens up many sectors in the life sciences, including water quality, soil sensing, veterinary diagnostics, as well as fluid diagnostics for the broader healthcare sector.

The Xibus team wants to nail their product right off the bat.

“Since food safety sensing is a crowded field, you only get one shot to impress your potential customers,“ Hartshorn says. “If your first product is flawed or not interesting enough, it can be very hard to open the door with these customers again. So we need to be sure our prototype is a game-changer. That’s what’s keeping us awake at night.”

Greener, more efficient natural gas filtration

by Helen Knight | MIT News |

Natural gas and biogas have become increasingly popular sources of energy throughout the world in recent years, thanks to their cleaner and more efficient combustion process when compared to coal and oil.

However, the presence of contaminants such as carbon dioxide within the gas means it must first be purified before it can be burnt as fuel.

Traditional processes to purify natural gas typically involve the use of toxic solvents and are extremely energy-intensive.

As a result, researchers have been investigating the use of membranes as a way to remove impurities from natural gas in a more cost-effective and environmentally friendly way, but finding a polymer material that can separate gases quickly and effectively has so far proven a challenge.

Now, in a paper published today in the journal Advanced Materials, researchers at MIT describe a new type of polymer membrane that can dramatically improve the efficiency of natural gas purification while reducing its environmental impact.

The membrane, which has been designed by an interdisciplinary research team at MIT, is capable of processing natural gas much more quickly than conventional materials, according to lead author Yuan He, a graduate student in the Department of Chemistry at MIT.

“Our design can process a lot more natural gas — removing a lot more carbon dioxide — in a shorter amount of time,” He says.

Existing membranes are typically made using linear strands of polymer, says Zachary Smith, the Joseph R. Mares Career Development Professor of Chemical Engineering at MIT, who led this research effort.

“These are long-chain polymers, which look like cooked spaghetti noodles at a molecular level,” he says. “You can make these cooked spaghetti noodles more rigid, and in so doing you create spaces between the noodles that change the packing structure and the spacing through which molecules can permeate.”

However, such materials are not sufficiently porous to allow carbon dioxide molecules to permeate through them at a fast enough rate to compete with existing purification processes.

Instead of using long chains of polymers, the researchers have designed membranes in which the strands look like hairbrushes, with tiny bristles on each strand. These bristles allow the polymers to separate gases much more effectively.

“We have a new design strategy, where we can tune the bristles on the hairbrush, which allows us to precisely and systematically tune the material,” Smith says. “In doing so, we can create precise subnanometer spacings, and enable the types of interactions that we need, to create selective and highly permeable membranes.”

In experiments, the membrane was able to withstand unprecedented carbon dioxide feed pressures of up to 51 bar without suffering plasticization, the researchers report. This compares to around 34 bar for the best-performing materials. The membrane is also 2,000 -7,000 times more permeable than traditional membranes, according to the team.

Since the side-chains, or “bristles,” can be predesigned before being polymerized, it is much easier to incorporate a range of functions into the polymer, according to Francesco Benedetti, a visiting graduate student within Smith’s research lab in the Department of Chemical Engineering at MIT.

The research also included Timothy Swager, the John D. MacArthur Professor of Chemistry, and Troy Van Voorhis, the Haslam and Dewey Professor of Chemistry, MIT graduate students Hong-Zhou Ye and Sharon Lin, M. Grazia DeAngelis at the University of Bologna, and Chao Liu and Yanchuan Zhao at the Chinese Academy of Sciences.

“The performance of the material can be tuned by making very subtle changes in the side-chains, or brushes, that we predesign,” Benedetti says. “That’s very important, because it means we can target very different applications, just by making very subtle changes.”

What’s more, the researchers have discovered that their hairbrush polymers are better able to withstand conditions that would cause other membranes to fail.

In existing membranes, the long-chain polymer strands overlap one another, sticking together to form solid-state films. But over time the polymer strands slide over each other, creating a physical and chemical instability.

In the new membrane design, in contrast, the polymer bristles are all connected by a long-chain strand, which acts as a backbone. As a result, the individual bristles are unable to move, creating a more stable membrane material.

This stability gives the material unprecedented resistance to a process known as plasticization, in which polymers swell in the presence of aggressive feedstocks such as carbon dioxide, Smith says.

“We’ve seen stability that we’ve never seen before in traditional polymers,” he says.

Using polymer membranes for gas separation offers high energy efficiency, minimal environmental impact, and simple and continuous operation, but existing commercial materials have low permeance and moderate selectivity, making them less competitive than other more energy-intensive processes, says Yan Xia, an assistant professor of chemistry at Stanford University, who was not involved in the research.

“The membranes from these polymers exhibit very high permeance for several industrially important gases,” Xia says. “Further, these polymers exhibit little undesired plasticization as the gas pressure is increased, despite their relatively flexible backbone, making them desired materials for carbon dioxide-related separations.”

The researchers are now planning to carry out a systematic study of the chemistry and structure of the brushes, to investigate how this affects their performance, He says.

“We are looking for the most effective chemistry and structure for helping the separation process.”

The team are also hoping to investigate the use of their membrane designs in other applications, including carbon capture and storage, and even in separating liquids.

Squire Booker PhD ’94 to speak at 2019 Investiture of Doctoral Hoods and Degree Conferral Ceremony

by MIT Institute Events |

Chancellor Cynthia Barnhart announced today that Squire J. Booker PhD ’94 will be the guest speaker at MIT’s 2019 Investiture of Doctoral Hoods and Degree Conferral Ceremony. Booker is the Evan Pugh Professor of chemistry and of biochemistry and molecular biology and Eberly Family Distinguished Chair in Science at Penn State University, and an investigator with the Howard Hughes Medical Institute.

“Professor Booker is an outstanding researcher and educator who embodies the MIT mission of advancing knowledge for the betterment of humankind,” said Chancellor Barnhart, host of the ceremony, which will make its Killian Court debut this year. “As they begin a new chapter in their lives, our candidates will find lessons and inspiration in Professor Booker’s remarkable professional and personal story. It will be an honor to welcome him home to MIT, and thrilling to hear him speak from the storied Killian Court stage.”

The speaker selection process engages faculty and doctoral students to identify MIT alumni whose acumen, experience, and insight illuminate possible futures for new PhDs and ScDs. Eric Grimson, chancellor for academic advancement, chairs the Commencement Committee. “This is an especially exciting graduation for our doctoral candidates, as we confer their degrees together with their academic hoods for the first time,” he said. “We are exhilarated to welcome Professor Booker as our guest speaker on June 6.”

Booker attended Austin College in Sherman, Texas, where he earned a bachelor’s degree in chemistry and was a Minnie Stevens Piper Scholar. In the summer of 1986, he conducted research at MIT as a member of a cohort of six students who participated in the very first MIT Summer Research Program, which has now blossomed into an extensive program that welcomes approximately 40 interns from underrepresented backgrounds each year in a multitude of disciplines. He earned his doctoral degree in biochemistry at MIT in 1994, as well as a National Science Foundation–NATO Fellowship for postdoctoral studies at Université René Descartes in Paris, France. Honors continued in 1996 with a National Institutes of Health Postdoctoral Fellowship for study at the Institute for Enzyme Research at the University of Wisconsin.

A member of the Penn State faculty since 1999, Booker was the recipient of a 2002 National Science Foundation Faculty Early Career Development (CAREER) award. In 2004, he visited the White House to receive the Presidential Early Career Award for Scientists and Engineers. The award, conferred by President George W. Bush, recognized Booker’s research on enzyme reactions — including his work on an enzyme involved in the synthesis of unusual fatty acids that are needed by the bacteria responsible for most cases of tuberculosis — and his leadership as an educator and mentor. In 2011, he received the American Chemical Society’s Arthur C. Cope Scholar Award, which is given “to recognize and encourage excellence in organic chemistry.”

Booker was promoted to associate professor at Penn State in 2005 and, in 2013, professor. In 2015, he was named an investigator of the Howard Hughes Medical Institute, a science philanthropy organization with the mission to advance biomedical research and science education for the benefit of humanity. He was appointed in 2017 to the Eberly Distinguished Chair in Science, one of the highest honors awarded to faculty members in the Penn State Eberly College of Science.

According to a February 2018 announcement by Penn State, “Booker’s main research interests include deciphering the molecular details by which enzymes — a special class of proteins — catalyze reactions in the cell. He uses the insight gained to manipulate these reactions for various objectives, ranging from the production of biofuels to the development of antibacterial agents. His laboratory garnered international attention for elucidating a pathway by which disease-causing bacteria, such as methicillin-resistant Staphylococcus aureus, evade entire classes of commonly used antibiotics.” Penn State further notes Booker’s acclaim for research on enzymes employing extremely reactive molecules, known as free radicals, to catalyze their reactions. He has published more than 100 scientific papers in journals, including Science, Nature Chemical Biology, the Journal of the American Chemical Society, and Proceedings of the National Academy of Sciences, and he has served as guest editor for Current Opinion in Chemical Biology, Biochimica Biophysica Acta, Proceedings of the National Academy of Sciences, and the Journal of Biological Chemistry.

Booker is dedicated to mentoring rising scientists and to spurring students in underrepresented groups to consider STEM careers: To date, he has mentored 18 graduate students, nearly 50 undergraduate students, 16 postdocs and research scientists, and two high school students. “Squire Booker is not just a prolific and path-breaking researcher,” enthuses Professor Timothy Jamison, head of the Department of Chemistry, “his mentoring leadership is shaping the future of our field — and contributing to the pipeline of scholars in science. Moreover, I am grateful for his ongoing and invaluable service to our department and to MIT as a member of our Visiting Committee.”

Booker is past-chair of the Minority Affairs Committee of the American Society of Biochemistry and Molecular Biology, and was co-organizer of the society’s 2016 annual meeting. He is a fellow of the American Association for the Advancement of Science and a member of the American Academy of Arts and Sciences.

The 2019 Investiture of Doctoral Hoods and Degree Conferral Ceremony will take place on June 6 at 10 a.m. on Killian Court. The ceremony is open to family, friends, and mentors of doctoral candidates; no tickets are required.

School of Science announces 2019 Infinite Mile Awards

by School of Science |

The MIT School of Science has announced the winners of the 2019 Infinite Mile Award, which is presented annually to staff members within the school who demonstrate exemplary dedication to making MIT a better place.

Nominated by their colleagues, these winners are notable for their unrelenting and extraordinary hard work in their positions, which can include mentoring fellow community members, innovating new solutions to problems big and small, building their communities, or going far above and beyond their job descriptions to support the goals of their home departments, labs, and research centers.

The 2019 Infinite Mile Award winners are:

Christine Brooks, an administrative assistant in the Department of Chemistry, nominated by Mircea Dincă and several members of the Dincă, Schrock, and Cummins groups;

Annie Cardinaux, a research specialist in the Department of Brain and Cognitive Sciences, nominated by Pawan Sinha;

Kimberli DeMayo, a human resources consultant in the Department of Mathematics, nominated by Nan Lin, Dennis Porche, and Paul Seidel, with support from several other faculty members;

Arek Hamalian, a technical associate at the Picower Institute for Learning and Memory, nominated by Susumu Tonegawa;

Jonathan Harmon, an administrative assistant in the Department of Mathematics, nominated by Pavel Etingof and Kimberli DeMayo, with support from several other faculty members;

Tanya Khovanova, a lecturer in the Department of Mathematics, nominated by Pavel Etingof, David Jerison, and Slava Gerovitch;

Kelley Mahoney, an SRS financial staff member in the Kavli Institute for Astrophysics and Space Research, nominated by Sarah Brady, Michael McDonald, Anna Frebel, Jacqueline Hewitt, Jack Defandorf, and Stacey Sullaway;

Walter Massefski, the director of instrumentation facility in the Department of Chemistry, nominated by Timothy F. Jamison and Richard Wilk;

Raleigh McElvery, a communications coordinator in the Department of Biology, nominated by Vivian Siegel with support from Amy Keating, Julia Keller, and Erika Reinfeld; and

Kate White, an administrative officer in the Department of Brain and Cognitive Sciences, nominated by Jim DiCarlo, Michale Fee, Sara Cody-Larnard, Rachel Donahue, Federico Chiavazza, Matthew Regan, Gayle Lutchen, and William Lawson.

The recipients will receive a monetary award in addition to being honored at a celebratory reception, along with their peers, family and friends, and the recipients of the 2019 Infinite Kilometer Award this month.

The chemist and the stage

by Kailey Tse-Harlow | Division of Student Life |

Audrey Pillsbury has many different identities on campus: She is a musician and composer, she rows for the women’s openweight crew, and she studies chemistry (Course 5). Now she is exploring her identity as a second-generation Asian-American through her first collaborative musical, “The Jade Bracelet.”

Encouraged by a group of friends and professors, Pillsbury channeled her lifelong passion for music and dance to tell a story about cultures, family dynamics, and interracial relationships that are part of Pillsbury’s reality, being half Chinese and half Caucasian.

“The Jade Bracelet” is about members of the Wong family, who immigrate to America to escape China’s one-child policy. Later, the Wong sisters Jaden and Amy are seen dealing in high school dealing with stereotypes from both Asian and American cultures, interracial dating conflicts, and trying to balance different, and sometimes conflicting, identities. Pillsbury was able to connect with students from Harvard University, Wellesley College, the University of Massachusetts at Boston, Berklee College of Music, and other area schools who had experienced similar issues growing up in multicultural families.

“I want to feel close to my Asian roots but what does that mean?” says Pillsbury. “I’ve never been to Asia. I love Chinese food but what does that mean? I think those are the moments I had with my own mother and trying to figure out her past and to see things from her perspective”

As an MIT Burchard Scholar, Pillsbury discovered many options for sharing her experiences through the humanities, arts, and social sciences, which led her to write “The Jade Bracelet” libretto. “Being at MIT has given me access to a lot of resources. I have this platform where people will sort of care about what I’ve written or what I’ve done. Fellow students want to see what their fellow students came up with,” says Pillsbury.

“The Jade Bracelet” is more than just songs and dialogue for Pillsbury. “It’s really about putting all of these people’s experiences together, the process we’ve had in making it come together, and this journey,” she says. “Being Asian is a really important part of who I am. No one should be color blind. We should all see what each other for which cultures and backgrounds are important to us.”

Being a woman in a STEM field, Pillsbury sees art as a release, and she encourages MIT students to explore more within the arts field by getting creative on campus and telling their own stories.

“We have so many creative people here. I know it’s hard because at MIT we have to carve time out of our day,” she says. “You have to make the time to do it but we just have so many creative people and you have all the resources here.”

Pillsbury wants to continue writing music while she begins her full-time position at Raytheon Space and Airborne Systems this fall. In the meantime, the MIT Theater Guild put on two staged readings of “The Jade Bracelet” this month in Kresge Auditorium’s Little Theater.

Exotic “second sound” phenomenon observed in pencil lead

by Jennifer Chu | MIT News Office |

The next time you set a kettle to boil, consider this scenario: After turning the burner off, instead of staying hot and slowly warming the surrounding kitchen and stove, the kettle quickly cools to room temperature and its heat hurtles away in the form of a boiling-hot wave.

We know heat doesn’t behave this way in our day-to-day surroundings. But now MIT researchers have observed this seemingly implausible mode of heat transport, known as “second sound,” in a rather commonplace material: graphite — the stuff of pencil lead.

At temperatures of 120 kelvin, or -240 degrees Fahrenheit, they saw clear signs that heat can travel through graphite in a wavelike motion. Points that were originally warm are left instantly cold, as the heat moves across the material at close to the speed of sound. The behavior resembles the wavelike way in which sound travels through air, so scientists have dubbed this exotic mode of heat transport “second sound.”

The new results represent the highest temperature at which scientists have observed second sound. What’s more, graphite is a commercially available material, in contrast to more pure, hard-to-control materials that have exhibited second sound at 20 K, (-420 F) — temperatures that would be far too cold to run any practical applications.

The discovery, published today in Science, suggests that graphite, and perhaps its high-performance relative, graphene, may efficiently remove heat in microelectronic devices in a way that was previously unrecognized.

“There’s a huge push to make things smaller and denser for devices like our computers and electronics, and thermal management becomes more difficult at these scales,” says Keith Nelson, the Haslam and Dewey Professor of Chemistry at MIT. “There’s good reason to believe that second sound might be more pronounced in graphene, even at room temperature. If it turns out graphene can efficiently remove heat as waves, that would certainly be wonderful.”

The result came out of a long-running interdisciplinary collaboration between Nelson’s research group and that of Gang Chen, the Carl Richard Soderberg Professor of Mechanical Engineering and Power Engineering. MIT co-authors on the paper are lead authors Sam Huberman and Ryan Duncan, Ke Chen, Bai Song, Vazrik Chiloyan, Zhiwei Ding, and Alexei Maznev.

“In the express lane”

Normally, heat travels through crystals in a diffusive manner, carried by “phonons,” or packets of acoustic vibrational energy. The microscopic structure of any crystalline solid is a lattice of atoms that vibrate as heat moves through the material. These lattice vibrations, the phonons, ultimately carry heat away, diffusing it from its source, though that source remains the warmest region, much like a kettle gradually cooling on a stove.

The kettle remains the warmest spot because as heat is carried away by molecules in the air, these molecules are constantly scattered in every direction, including back toward the kettle. This “back-scattering” occurs for phonons as well, keeping the original heated region of a solid the warmest spot even as heat diffuses away.

However, in materials that exhibit second sound, this back-scattering is heavily suppressed. Phonons instead conserve momentum and hurtle away en masse, and the heat stored in the phonons is carried as a wave. Thus, the point that was originally heated is almost instantly cooled, at close to the speed of sound.

Previous theoretical work in Chen’s group had suggested that, within a range of temperatures, phonons in graphene may interact predominately in a momentum-conserving fashion, indicating that graphene may exhibit second sound. Last year, Huberman, a member of Chen’s lab, was curious whether this might be true for more commonplace materials like graphite.

Building upon tools previously developed in Chen’s group for graphene, he developed an intricate model to numerically simulate the transport of phonons in a sample of graphite. For each phonon, he kept track of every possible scattering event that could take place with every other phonon, based upon their direction and energy. He ran the simulations over a range of temperatures, from 50 K to room temperature, and found that heat might flow in a manner similar to second sound at temperatures between 80 and 120 K.

Huberman had been collaborating with Duncan, in Nelson’s group, on another project. When he shared his predictions with Duncan, the experimentalist decided to put Huberman’s calculations to the test.

“This was an amazing collaboration,” Chen says. “Ryan basically dropped everything to do this experiment, in a very short time.”

“We were really in the express lane with this,” Duncan adds.

Upending the norm

Duncan’s experiment centered around a small, 10-square-millimeter sample of commercially available graphite.

Using a technique called transient thermal grating, he crossed two laser beams so that the interference of their light generated a “ripple” pattern on the surface of a small sample of graphite. The regions of the sample underlying the ripple’s crests were heated, while those that corresponded to the ripple’s troughs remained unheated. The distance between crests was about 10 microns.

Duncan then shone onto the sample a third laser beam, whose light was diffracted by the ripple, and its signal was measured by a photodetector. This signal was proportional to the height of the ripple pattern, which depended on how much hotter the crests were than the troughs. In this way, Duncan could track how heat flowed across the sample over time.

If heat were to flow normally in the sample, Duncan would have seen the surface ripples slowly diminish as heat moved from crests to troughs, washing the ripple pattern away. Instead, he observed “a totally different behavior” at 120 K.

Rather than seeing the crests gradually decay to the same level as the troughs as they cooled, the crests actually became cooler than the troughs, so that the ripple pattern was inverted — meaning that for some of the time, heat actually flowed from cooler regions into warmer regions.

“That’s completely contrary to our everyday experience, and to thermal transport in almost every material at any temperature,” Duncan says. “This really looked like second sound. When I saw this I had to sit down for five minutes, and I said to myself, ‘This cannot be real.’ But I ran the experiment overnight to see if it happened again, and it proved to be very reproducible.”

According to Huberman’s predictions, graphite’s two-dimensional relative, graphene, may also exhibit properties of second sound at even higher temperatures approaching or exceeding room temperature. If this is the case, which they plan to test, then graphene may be a practical option for cooling ever-denser microelectronic devices.

“This is one of a small number of career highlights that I would look to, where results really upend the way you normally think about something,” Nelson says. “It’s made more exciting by the fact that, depending on where it goes from here, there could be interesting applications in the future. There’s no question from a fundamental point of view, it’s really unusual and exciting.”

This research was funded in part by the Office of Naval Research, the Department of Energy, and the National Science Foundation.

Streamlining restaurant operations

by Zach Winn | MIT News Office |

People in the restaurant industry know a thing or two about execution. High operating costs, low profit margins, and the perishable nature of every establishment’s most important resource — food — make it essential to get things done with speed and efficiency.

It’s no surprise, then, that the startup Toast has found success developing technology to streamline restaurant operations. Since its launch in 2013, Toast has been building on its original point of sale (POS) software to address each step in the process of getting an order from a customer to the kitchen and back again. Today, the company offers hardware and software solutions including a kitchen display system for cooks, tablet-based and handheld POS devices for waitstaff, payroll and analytics features for managers, and online ordering and delivery options for customers.

The POS space includes some large, well-funded companies, but Toast founders Aman Narang ’04 SM ’06, Jonathan Grimm ’07, and Steve Fredette ’06 have stayed focused on the customer and tried to make developing impactful solutions the focal point of everything they do.

That customer-focused mindset has worked: In 2017, Deloitte named Toast the third-fastest-growing technology company in the country, reporting revenue growth over 30,000 percent between 2013 and 2016.

Fredette says they didn’t realize how special their company was until their fundraising round last year, when Toast was valued at $1.4 billion.

“Once we started talking to investors who had compared our metrics to our competitors and seen the whole market, it started to become clear we were doing things differently,” Fredette says. “We’ve had a level of customer success that is much higher, I think, than what others have had. … I think a lot of that ultimately comes down to good execution.”

Just don’t congratulate the founders quite yet. Even now, Fredette says the company is in growth mode, and he still talks about the business like it’s a scrappy startup. That’s a useful way of looking at things if you want to be a market leader in the restaurant industry, which was projected to do more than $800 billion in sales in the U.S. last year. It’s also a perspective that was partially borne out of the founders’ experience at MIT.

“One of the biggest benefits of MIT is just being surrounded by a network of people that are ambitious and thinking about big ideas,” Fredette says. “That’s a very positive, infectious thing, and that was certainly influential for me. Coming out of MIT also gives you a confidence that you can do anything. You look around and think, ‘These are the people that are going to change the world, and I’m a part of that group.’”

Perhaps another thing driving the founders is the lack of confidence potential investors showed in the company early on. Then again, Toast’s early operations didn’t exactly inspire visions of Boston’s next billion-dollar startup.

Humble beginnings

Toast’s three founders set out to start a company after working together at Endeca, a software company that was bought by Oracle in 2011. Their initial idea was to make an ecommerce app for the restaurant industry, but they kept running into problems with the dated POS software many restaurants were using at the time, so they decided to build a better POS system.

After considering some areas to lease office space, the founders decided it would be cheaper to refinish the basement in Narang’s house and set up operations there. For the next nine months, Narang’s wife, who worked as a teacher, would wake up at 6 a.m. to find members of Toast’s small team coding in her basement, and would often go to sleep at night with the same people there.

Investors looking at Toast could be forgiven for failing to see the company’s potential at the time. Although the founders had worked in managerial roles at Endeca, they had very little experience running a startup. Narang and Grimm had majored in computer science at MIT, while Fredette’s degree was in chemistry, and the company’s “operations” looked more like a disheveled group of hackers in a basement — one of whom was seriously testing his wife’s patience.

Still, Fredette says some of Toast’s first customers were ditching market-leading POS solutions like Square and Micro for the company’s early product.

“We were always very customer-driven,” Fredette says. “Not having spent a lot of time in the restaurant industry ourselves, we didn’t presuppose we knew what our customers needed. We also had a lot of customer-facing experience from Endeca, so the best way to figure out what to build was to work with customers and deeply understand their problems.”

That approach ensured the founders were only building things their customers needed, and they quickly learned there was a lot to build. Fredette says they built five to 10 features for each of their first 10 customers or so until their needs started to converge.

Eventually, the company outgrew Narang’s basement, but the founders still didn’t feel ready to move into an office space, so they rented an apartment in Central Square. Fredette still remembers the unorthodox “office” holiday party Toast threw in December 2013. That arrangement came to an abrupt end when the landlord realized they were running a business.

By that time, however, it was clear Toast was on to something, and the founders finally felt comfortable enough to lease office space. It turned out to be a good investment.

“We couldn’t scale out quickly enough,” Fredette remembers. “We were basically scaling as fast as we could to fulfill what we saw as the demand from the market. It was a good problem to have as a company.”

Fredette says the founders have endured the inevitable pains that come from running a fast-growing company, learning in real-time as they overhauled processes, systems, and teams. Now at 1,400 employees, the founders have learned to look at scaling as an opportunity to improve the company.

They’ve also tried to maintain the spirit of the basement-based coding marathons of their early days by avoiding a top-down development structure and giving people the freedom to work on their own ideas. Fredette says Toast’s leadership team also tries to set big goals for the company.

“One of the most important things in terms of innovation is to have a big vision and set ambitious goals. Necessity is the mother of innovation,” Fredette says. “If you say we need to go to the moon, then innovation often happens. You could say the same thing for a lot of the MIT work that happens in research labs and the early projects that led to the internet. That pursuit of big goals then led to innovation, so I think setting big goals is an important part of a culture of innovation.”

But Fredette believes the best way to maintain success is to do what’s worked since the beginning: stay focused on the customer.

“We’re still very committed to our customers and to helping them achieve their own goals,” Fredette says. “We always ask our customers how we can help them thrive, how we can help them do more of what they love. And they have lots of ideas, so there’s a lot in front of us to increase our impact.”

National competition veterans pay it forward at regional science contest

by Laura Carter | School of Science |

On Saturday, Feb. 23, more than 100 middle school students gathered at MIT to compete in the annual Northeast Regional Middle School Science Bowl.

The event, now in its fourth year, was coordinated and executed by Kathleen Schwind, a senior in the five-year program in the MIT Department of Urban Studies and Planning, and Songela Chen, a senior in the MIT Department of Chemistry. Many of the organizers and volunteers, including Schwind and Chen, are veterans of middle and high school National Science Bowl (NSB) competitions.

“The Northeast Middle School Science Bowl really is something special,” says Schwind. “[It’s] an event run by young people for young people, and an opportunity to not only celebrate the youth in our community, but also inspire them to continue being a part of NSB and to give back to other young people one day, too.”

The first several rounds were a round-robin style warmup for the 21 teams of four or five middle school students representing 10 schools from Maine, New Hampshire, and Massachusetts. Correctly answered questions in fields such as life science, physical science, earth and space science, and math won a team points and the chance at a bonus question. An incorrect answer passed the question over to the other team, who could then attempt an answer.

After a lunch break and group photo, elimination rounds began. Those knocked out switched their attention to fun engineering challenges such as building a tower out of supplied paper bags, aluminum foil, cups, and straws. At the end of the day, eliminated participants watched the tight race for third place, followed by a championship round for the title.

This year, that title went to Jonas Clarke Middle School Team One from Lexington, Massachusetts. William Diamond Middle School Team One, also from Lexington, took second. The winning team received a coveted trophy and the opportunity to represent the Northeast in the National Science Bowl hosted by the U.S. Department of Energy in Washington in April.

However, the competition was not about winning, said several participants, all of whom wore matching green shirts stating, “Keep calm and science bowl on.” Instead, it was about the fun and comradery of being part of a team. “It gives you purpose,” said a seventh-grade student from William Diamond Middle School. Being on MIT’s campus was an opportunity to interact with an even larger scientific community. “It’s fun and confusing and kind of scary,” said an eighth grader from Jonas Clarke, who wants to be a marine biologist. “Scary because of the number of people and how big MIT is,” she clarified with a laugh.

As a student at MIT, Schwind founded the Northeast Regional Middle School Science Bowl when she learned the region lacked a local chapter. She used experience gained from founding and coordinating such events since age 16 — the youngest coordinator to date.

“The science bowl is extremely valuable for promoting science and the broader appreciation of science, so I am delighted to continue my support through MIT’s School of Science for this year’s event,” School of Science Dean Michael Sipser says of his recurring interest in sponsorship of the event.

Schwind also recruited the help of fellow National Science Bowl alumni, such as Chen. Although both will graduate in the spring, Schwind and Chen plan to continue running this event next year, remotely if necessary.

As a seven-year alumna of middle and high school science bowls, Chen says it was a motivator for her career in science and she hopes to pay it forward, “to show middle school students how valuable and rewarding science can be.”

“There is nothing like seeing a competitor have that sparkle in their eyes after the event and tell you that they now want to be a scientist or mathematician and go to MIT one day,” Schwind says.

QS World University Rankings rates MIT No. 1 in 11 subjects for 2019

by MIT News Office |

MIT has been honored with 11 No. 1 subject rankings in the QS World University Rankings for 2019.

The Institute received a No. 1 ranking in the following QS subject areas: Chemistry; Computer Science and Information Systems; Chemical Engineering; Civil and Structural Engineering; Electrical and Electronic Engineering; Mechanical, Aeronautical and Manufacturing Engineering; Linguistics; Materials Science; Mathematics; Physics and Astronomy; and Statistics and Operational Research.

MIT also placed second in six subject areas: Accounting and Finance; Architecture/Built Environment; Biological Sciences; Earth and Marine Sciences; Economics and Econometrics; and Environmental Sciences.

Quacquarelli Symonds Limited subject rankings, published annually, are designed to help prospective students find the leading schools in their field of interest. Rankings are based on research quality and accomplishments, academic reputation, and graduate employment.

MIT has been ranked as the No. 1 university in the world by QS World University Rankings for seven straight years.

Quantum dots can spit out clone-like photons

by David L. Chandler | MIT News Office |

In the global quest to develop practical computing and communications devices based on the principles of quantum physics, one potentially useful component has proved elusive: a source of individual particles of light with perfectly constant, predictable, and steady characteristics. Now, researchers at MIT and in Switzerland say they have made major steps toward such a single photon source.

The study, which involves using a family of materials known as perovskites to make light-emitting particles called quantum dots, appears today in the journal Science. The paper is by MIT graduate student in chemistry Hendrik Utzat, professor of chemistry Moungi Bawendi, and nine others at MIT and at ETH in Zurich, Switzerland.

The ability to produce individual photons with precisely known and persistent properties, including a wavelength, or color, that does not fluctuate at all, could be useful for many kinds of proposed quantum devices. Because each photon would be indistinguishable from the others in terms of its quantum-mechanical properties, it could be possible, for example, to delay one of them and then get the pair to interact with each other, in a phenomenon called interference.

“This quantum interference between different indistinguishable single photons is the basis of many optical quantum information technologies using single photons as information carriers,” Utzat explains. “But it only works if the photons are coherent, meaning they preserve their quantum states for a sufficiently long time.”

Many researchers have tried to produce sources that could emit such coherent single photons, but all have had limitations. Random fluctuations in the materials surrounding these emitters tend to change the properties of the photons in unpredictable ways, destroying their coherence. Finding emitter materials that maintain coherence and are also bright and stable is “fundamentally challenging,” Utzat says. That’s because not only the surroundings but even the materials themselves “essentially provide a fluctuating bath that randomly interacts with the electronically excited quantum state and washes out the coherence,” he says.

“Without having a source of coherent single photons, you can’t use any of these quantum effects that are the foundation of optical quantum information manipulation,” says Bawendi, who is the Lester Wolfe Professor of Chemistry. Another important quantum effect that can be harnessed by having coherent photons, he says, is entanglement, in which two photons essentially behave as if they were one, sharing all their properties.

Previous chemically-made colloidal quantum dot materials had impractically short coherence times, but this team found that making the quantum dots from perovskites, a family of materials defined by their crystal structure, produced coherence levels that were more than a thousand times better than previous versions. The coherence properties of these colloidal perovskite quantum dots are now approaching the levels of established emitters, such as atom-like defects in diamond or quantum dots grown by physicists using gas-phase beam epitaxy.

One of the big advantages of perovskites, they found, was that they emit photons very quickly after being stimulated by a laser beam. This high speed could be a crucial characteristic for potential quantum computing applications. They also have very little interaction with their surroundings, greatly improving their coherence properties and stability.

Such coherent photons could also be used for quantum-encrypted communications applications, Bawendi says. A particular kind of entanglement, called polarization entanglement, can be the basis for secure quantum communications that defies attempts at interception.

Now that the team has found these promising properties, the next step is to work on optimizing and improving their performance in order to make them scalable and practical. For one thing, they need to achieve 100 percent indistinguishability in the photons produced. So far, they have reached 20 percent, “which is already very remarkable,” Utzat says, already comparable to the coherences reached by other materials, such as atom-like fluorescent defects in diamond, that are already established systems and have been worked on much longer.

“Perovskite quantum dots still have a long way to go until they become applicable in real applications,” he says, “but this is a new materials system available for quantum photonics that can now be optimized and potentially integrated with devices.”

It’s a new phenomenon and will require much work to develop to a practical level, the researchers say. “Our study is very fundamental,” Bawendi notes. “However, it’s a big step toward developing a new material platform that is promising.”

The work was supported by the U.S. Department of Energy, the National Science Foundation, and the Swiss Federal Commission for Technology and Innovation.