|A drawing illustrates the unusual topological landscape around a pair of features known as exceptional points (red dots), showing the emergence of a Fermi arc (pink line at center), and exotic polarization contours that form a Mobius-strip-like texture (top and bottom strips). Courtesy of the researchers|
Topological effects, such as those found in crystals whose surfaces conduct electricity while their bulk does not, have been an exciting topic of physics research in recent years and were the subject of the 2016 Nobel Prize in physics. Now, a team of researchers at MIT and elsewhere has found novel topological phenomena in a different class of systems — open systems, where energy or material can enter or be emitted, as opposed to closed systems with no such exchange with the outside.
This could open up some new realms of basic physics research, the team says, and might ultimately lead to new kinds of lasers and other technologies.
The results are being reported in the journal Science, in a paper by recent MIT graduate Hengyun “Harry” Zhou, MIT visiting scholar Chao Peng (a professor at Peking University), MIT graduate student Yoseob Yoon, recent MIT graduates Bo Zhen and Chia Wei Hsu, MIT Professor Marin Soljačić, the Francis Wright Davis Professor of Physics John Joannopoulos, the Haslam and Dewey Professor of Chemistry Keith Nelson, and the Lawrence C. and Sarah W. Biedenharn Career Development Assistant Professor Liang Fu.
In most research in the field of topological physical effects, Soljačić says, so-called “open” systems — in physics terms, these are known as non-Hermitian systems — were not studied much in experimental work. The complexities involved in measuring or analyzing phenomena in which energy or matter can be added or lost through radiation generally make these systems more difficult to study and analyze in a controlled fashion.
But in this work, the team used a method that made these open systems accessible, and “we found interesting topological properties in these non-Hermitian systems,” Zhou says. In particular, they found two specific kinds of effects that are distinctive topological signatures of non-Hermitian systems. One of these is a kind of band feature they refer to as a bulk Fermi arc, and the other is an unusual kind of changing polarization, or orientation of light waves, emitted by the photonic crystal used for the study.
Photonic crystals are materials in which billions of very precisely shaped and oriented tiny holes are made, causing light to interact in unusual ways with the material. Such crystals have been actively studied for the exotic interactions they induce between light and matter, which hold the potential for new kinds of light-based computing systems or light-emitting devices. But while much of this research has been done using closed, Hermitian systems, most of the potential real-world applications involve open systems, so the new observations made by this team could open up whole new areas of research, the researchers say.
Fermi arcs, one of the unique phenomena the team found, defy the common intuition that energy contours are necessarily closed curves. They have been observed before in closed systems, but in those systems they always form on the two-dimensional surfaces of a three-dimensional system. In the new work, for the first time, the researchers found a Fermi arc that resides in the bulk of a system. This bulk Fermi arc connects two points in the emission directions, which are known as exceptional points — another characteristic of open topological systems.
The other phenomenon they observed consists of a field of light in which the polarization changes according to the emission direction, gradually forming a half-twist as one follows the direction along a loop and returns back to the starting point. “As you go around this crystal, the polarization of the light actually flips,” Zhou says.
This half-twist is analogous to a Möbius strip, he explains, in which a strip of paper is twisted a half-turn before connecting it to its other end, creating a band that has only one side. This Möbius-like twist in light polarization, Zhen says, could in theory lead to new ways of increasing the amount of data that could be sent through fiber-optic links.
The new work is “mostly of scientific interest, rather than technological,” Soljačić says. Zhen adds that “now we have this very interesting technique to probe the properties of non-Hermitian systems.” But there is also a possibility that the work may ultimately lead to new devices, including new kinds of lasers or light-emitting devices, they say.
The new findings were made possible by earlier research by many of the same team members, in which they found a way to use light scattered from a photonic crystal to produce direct images that reveal the energy contours of the material, rather than having to calculate those contours indirectly.
“We had a hunch” that such half-twist behavior was possible and could be “quite interesting,” Soljačić says, but actually finding it required “quite a bit of searching to figure out, how do we make it happen?”
“Perhaps the most ingenious aspect of this work is that the authors use the fact that their system must necessarily lose photons, which is usually an obstacle and annoyance, to access new topological physics,” says Mikael Rechtsman, an assistant professor of physics at Pennsylvania State University who was not involved in this work. “Without the loss … this would have required highly complex 3-D fabrication methods that likely would not have been possible.” In other words, he says, the technique they developed “gave them access to 2-D physics that would have been conventionally thought impossible.”
The work was supported by the Army Research Office through the Institute for Soldier Nanotechnologies; S3TEC, an Energy Frontier Research Center funded by the U.S. Department of Energy; the U.S. Air Force; and the National Science Foundation.
Read more at the MIT News Office.
David L. Chandler | MIT News Office
January 11, 2018
|A new machine-learning system for analyzing materials “recipes” uses a variational autoencoder, which squeezes data (left-hand circles) down into a more compact form (center circles) before attempting to re-expand it into its original form (right-hand circles). If the autoencoder is successfully trained, the compact representation will capture the data’s most salient characteristics. Image, Chelsea Turner, MIT|
Last month, three MIT materials scientists and their colleagues published a paper describing a new artificial-intelligence system that can pore through scientific papers and extract “recipes” for producing particular types of materials.
That work was envisioned as the first step toward a system that can originate recipes for materials that have been described only theoretically. Now, in a paper in the journal npj Computational Materials, the same three materials scientists, with a colleague in MIT’s Department of Electrical Engineering and Computer Science (EECS), take a further step in that direction, with a new artificial-intelligence system that can recognize higher-level patterns that are consistent across recipes.
For instance, the new system was able to identify correlations between “precursor” chemicals used in materials recipes and the crystal structures of the resulting products. The same correlations, it turned out, had been documented in the literature.
The system also relies on statistical methods that provide a natural mechanism for generating original recipes. In the paper, the researchers use this mechanism to suggest alternative recipes for known materials, and the suggestions accord well with real recipes.
The first author on the new paper is Edward Kim, a graduate student in materials science and engineering. The senior author is his advisor, Elsa Olivetti, the Atlantic Richfield Assistant Professor of Energy Studies in the Department of Materials Science and Engineering (DMSE). They’re joined by Kevin Huang, a postdoc in DMSE, and by Stefanie Jegelka, the X-Window Consortium Career Development Assistant Professor in EECS.
Sparse and scarce
Like many of the best-performing artificial-intelligence systems of the past 10 years, the MIT researchers’ new system is a so-called neural network, which learns to perform computational tasks by analyzing huge sets of training data. Traditionally, attempts to use neural networks to generate materials recipes have run up against two problems, which the researchers describe as sparsity and scarcity.
Any recipe for a material can be represented as a vector, which is essentially a long string of numbers. Each number represents a feature of the recipe, such as the concentration of a particular chemical, the solvent in which it’s dissolved, or the temperature at which a reaction takes place.
Since any given recipe will use only a few of the many chemicals and solvents described in the literature, most of those numbers will be zero. That’s what the researchers mean by “sparse.”
Similarly, to learn how modifying reaction parameters — such as chemical concentrations and temperatures — can affect final products, a system would ideally be trained on a huge number of examples in which those parameters are varied. But for some materials — particularly newer ones — the literature may contain only a few recipes. That’s scarcity.
“People think that with machine learning, you need a lot of data, and if it’s sparse, you need more data,” Kim says. “When you’re trying to focus on a very specific system, where you’re forced to use high-dimensional data but you don’t have a lot of it, can you still use these neural machine-learning techniques?”
Neural networks are typically arranged into layers, each consisting of thousands of simple processing units, or nodes. Each node is connected to several nodes in the layers above and below. Data is fed into the bottom layer, which manipulates it and passes it to the next layer, which manipulates it and passes it to the next, and so on. During training, the connections between nodes are constantly readjusted until the output of the final layer consistently approximates the result of some computation.
The problem with sparse, high-dimensional data is that for any given training example, most nodes in the bottom layer receive no data. It would take a prohibitively large training set to ensure that the network as a whole sees enough data to learn to make reliable generalizations.
The purpose of the MIT researchers’ network is to distill input vectors into much smaller vectors, all of whose numbers are meaningful for every input. To that end, the network has a middle layer with just a few nodes in it — only two, in some experiments.
The goal of training is simply to configure the network so that its output is as close as possible to its input. If training is successful, then the handful of nodes in the middle layer must somehow represent most of the information contained in the input vector, but in a much more compressed form. Such systems, in which the output attempts to match the input, are called “autoencoders.”
Autoencoding compensates for sparsity, but to handle scarcity, the researchers trained their network on not only recipes for producing particular materials, but also on recipes for producing very similar materials. They used three measures of similarity, one of which seeks to minimize the number of differences between materials — substituting, say, just one atom for another — while preserving crystal structure.
During training, the weight that the network gives example recipes varies according to their similarity scores.
Playing the odds
In fact, the researchers’ network is not just an autoencoder, but what’s called a variational autoencoder. That means that during training, the network is evaluated not only on how well its outputs match its inputs, but also on how well the values taken on by the middle layer accord with some statistical model — say, the familiar bell curve, or normal distribution. That is, across the whole training set, the values taken on by the middle layer should cluster around a central value and then taper off at a regular rate in all directions.
After training a variational autoencoder with a two-node middle layer on recipes for manganese dioxide and related compounds, the researchers constructed a two-dimensional map depicting the values that the two middle nodes took on for each example in the training set.
Remarkably, training examples that used the same precursor chemicals stuck to the same regions of the map, with sharp boundaries between regions. The same was true of training examples that yielded four of manganese dioxide’s common “polymorphs,” or crystal structures. And combining those two mappings indicated correlations between particular precursors and particular crystal structures.
“We thought it was cool that the regions were continuous,” Olivetti says, “because there’s no reason that that should necessarily be true.”
Variational autoencoding is also what enables the researchers’ system to generate new recipes. Because the values taken on by the middle layer adhere to a probability distribution, picking a value from that distribution at random is likely to yield a plausible recipe.
“This actually touches upon various topics that are currently of great interest in machine learning,” Jegelka says. “Learning with structured objects, allowing interpretability by and interaction with experts, and generating structured complex data — we integrate all of these.”
“‘Synthesizability’ is an example of a concept that is central to materials science yet lacks a good physics-based description,” says Bryce Meredig, founder and chief scientist at Citrine Informatics, a company that brings big-data and artificial-intelligence techniques to bear on materials science research. “As a result, computational screens for new materials have been hamstrung for many years by synthetic inaccessibility of the predicted materials. Olivetti and colleagues have taken a novel, data-driven approach to mapping materials syntheses and made an important contribution toward enabling us to computationally identify materials that not only have exciting properties but also can be made practically in the laboratory.”
The research was supported by the National Science Foundation, the Natural Sciences and Engineering Research Council of Canada, the U.S. Office of Naval Research, the MIT Energy Initiative, and the U.S. Department of Energy’s Basic Energy Science Program.
Larry Hardesty | MIT News Office
December 21, 2017
|This experimental setup was used by the team to measure the electrical output of a sample of solar cell material, under controlled conditions of varying temperature and illumination. The data from those tests was then used as the basis for computer modeling using statistical methods to predict the overall performance of the material in real-world operating conditions. Image, Riley Brandt|
The worldwide quest by researchers to find better, more efficient materials for tomorrow’s solar panels is usually slow and painstaking. Researchers typically must produce lab samples — which are often composed of multiple layers of different materials bonded together — for extensive testing.
Now, a team at MIT and other institutions has come up with a way to bypass such expensive and time-consuming fabrication and testing, allowing for a rapid screening of far more variations than would be practical through the traditional approach.
The new process could not only speed up the search for new formulations, but also do a more accurate job of predicting their performance, explains Rachel Kurchin, an MIT graduate student and co-author of a paper describing the new process that appears this week in the journal Joule. Traditional methods “often require you to make a specialized sample, but that differs from an actual cell and may not be fully representative” of a real solar cell’s performance, she says.
For example, typical testing methods show the behavior of the “majority carriers,” the predominant particles or vacancies whose movement produces an electric current through a material. But in the case of photovoltaic (PV) materials, Kurchin explains, it is actually the minority carriers — those that are far less abundant in the material — that are the limiting factor in a device’s overall efficiency, and those are much more difficult to measure. In addition, typical procedures only measure the flow of current in one set of directions — within the plane of a thin-film material — whereas it’s up-down flow that is actually harnessed in a working solar cell. In many materials, that flow can be “drastically different,” making it critical to understand in order to properly characterize the material, she says.
“Historically, the rate of new materials development is slow — typically 10 to 25 years,” says Tonio Buonassisi, an associate professor of mechanical engineering at MIT and senior author of the paper. “One of the things that makes the process slow is the long time it takes to troubleshoot early-stage prototype devices,” he says. “Performing characterization takes time — sometimes weeks or months — and the measurements do not always have the necessary sensitivity to determine the root cause of any problems.”
So, Buonassisi says, “the bottom line is, if we want to accelerate the pace of new materials development, it is imperative that we figure out faster and more accurate ways to troubleshoot our early-stage materials and prototype devices.” And that’s what the team has now accomplished. They have developed a set of tools that can be used to make accurate, rapid assessments of proposed materials, using a series of relatively simple lab tests combined with computer modeling of the physical properties of the material itself, as well as additional modeling based on a statistical method known as Bayesian inference.
The system involves making a simple test device, then measuring its current output under different levels of illumination and different voltages, to quantify exactly how the performance varies under these changing conditions. These values are then used to refine the statistical model.
“After we acquire many current-voltage measurements [of the sample] at different temperatures and illumination intensities, we need to figure out what combination of materials and interface variables make the best fit with our set of measurements,” Buonassisi explains. “Representing each parameter as a probability distribution allows us to account for experimental uncertainty, and it also allows us to suss out which parameters are covarying.”
The Bayesian inference process allows the estimates of each parameter to be updated based on each new measurement, gradually refining the estimates and homing in ever closer to the precise answer, he says.
In seeking a combination of materials for a particular kind of application, Kurchin says, “we put in all these materials properties and interface properties, and it will tell you what the output will look like.”
The system is simple enough that, even for materials that have been less well-characterized in the lab, “we’re still able to run this without tremendous computer overhead.” And, Kurchin says, making use of the computational tools to screen possible materials will be increasingly useful because “lab equipment has gotten more expensive, and computers have gotten cheaper. This method allows you to minimize your use of complicated lab equipment.”
The basic methodology, Buonassisi says, could be applied to a wide variety of different materials evaluations, not just solar cells — in fact, it may apply to any system that involves a computer model for the output of an experimental measurement. “For example, this approach excels in figuring out which material or interface property might be limiting performance, even for complex stacks of materials like batteries, thermoelectric devices, or composites used in tennis shoes or airplane wings.” And, he adds, “It is especially useful for early-stage research, where many things might be going wrong at once.”
Going forward, he says, “our vision is to link up this fast characterization method with the faster materials and device synthesis methods we’ve developed in our lab.” Ultimately, he says, “I’m very hopeful the combination of high-throughput computing, automation, and machine learning will help us accelerate the rate of novel materials development by more than a factor of five. This could be transformative, bringing the timelines for new materials-science discoveries down from 20 years to about three to five years.”
The research team also included Riley Brandt '11, SM '13, PhD '16; former postdoc Vera Steinmann; MIT graduate student Daniil Kitchaev and visiting professor Gerbrand Ceder, Chris Roat at Google Inc.; and Sergiu Levcenco and Thomas Unold at Hemholz Zentrum in Berlin. The work was supported by a Google Faculty Research Award, the U.S. Department of Energy, and a Total research grant.
David L. Chandler | MIT News Office
December 20, 2017
|The president of Croatia, Kolinda Grabar-Kitarović, visited MIT on Monday, Dec. 4. From left: MIT physicist Marin Soljačić; MIT President L. Rafael Reif; Croatian president Kolinda Grabar-Kitarović; and the dean of the MIT School of Science, Michael Sipser. Photo, Allegra Boverman|
Croatian president Kolinda Grabar-Kitarović visited MIT on Monday, Dec. 5, 2017, discussing research and innovation policy, and bestowing two medals upon MIT Professor Marin Soljačić.
The state visit began in the office of MIT President L. Rafael Reif, who greeted Grabar-Kitarović and engaged with her in a discussion, partly about the need to have more women pursue careers in science, engineering, and mathematics. Reif also exchanged formal gifts with Grabar-Kitarović.
While in the MIT president’s office, Grabar-Kitarović presented Soljačić with two medals. One, for his special contributions to science, is the Order of the Croatian Morning Star, bearing the image of Ruder Bošković (a noted 18th-century physicist and astronomer from Dubrovnik). The other medal, the Order of the Croatian Interlace, is for contributions to Croatia’s development, reputation, and the welfare of its citizens.
Soljačić is a physicist and native of Zagreb, Croatia, whose work in photonics has produced a variety of new applications in fields ranging from solar energy to novel types of lasers.
Grabar-Kitarović, who was elected president of Croatia in 2015, called the visit to MIT “very inspiring” when she met later with a panel of Croatian students — mostly graduate students and postdocs — who are enrolled at MIT. Soljačić and Michael Sipser, the dean of the School of Science at MIT, were also part of the discussion forum.
Sipser presented an overview of basic research in science at MIT, from astronomy and physics to neuroscience and biology, and noted some of the recent fundamental advances in which MIT has played a role — such as the observation of gravitational waves, for which MIT physicist Rainer Weiss recently received the Nobel Prize.
“In many cases I’ve found that what attracts people to come into science are these fundamental discoveries,” Sipser said.
Soljačić, who runs the Photonics and Modern Electro-Magnetics Group at MIT, presented the forum with an overview of his research group’s advances — which apply to a wide range of topics and technologies, including more efficient solar cells, wireless power transfer, optical neural networks, and privacy for touch screens.
During the forum, Soljačić said he was “very honored” to have received the awards from Grabar-Kitarović and the government of Croatia; for her part, Grabar-Kitarović said it was “an honor for me too” to have presented them.
Grabar-Kitarović solicited input from the students at the panel about ways of encouraging Croatian students to stay in the country — or return to it, after a spell of study elsewhere — and to help add to the country’s intellectual ecosystem. She also noted that her country needed to address the “lack of opportunity” that some talented students can face when it comes to gaining a foothold in academic research.
“I hope with the help of the wonderful young people around the table, we will be able to help by bringing more science and technology [research] to Croatia,” Grabar-Kitarović said.
Grabar-Kitarović is the first female president in Croatia’s history. (The country declared independence from the former Yugoslavia in 1991.) Before becoming president, she served in a variety of governmental positions, including a term as Croatia’s ambassador to the U.S., from 2008 to 2011.
The Croatian delegation also included Pjer Simunovic, Croatia’s current ambassador to the U.S.
Soljačić is one of four Croatian-born faculty members at MIT. The others are Tanja Bosak, an associate professor in the Department of of Earth, Atmospheric and Planetary Sciences; Silvija Gradečak, a professor in the Department of Materials Science and Engineering; and economist Drazen Prelec, a professor in the MIT Sloan School of Management and the Department of Economics.
Peter Dizikes | MIT News Office
December 5, 2017
|Illumination of a book (“Paradise Lost,” by John Milton) with the nanobionic light-emitting plants (two 3.5-week-old watercress plants). The book and the light-emitting watercress plants were placed in front of a reflective paper to increase the influence from the light emitting plants to the book pages. Image, Seon-Yeong Kwak|
Imagine that instead of switching on a lamp when it gets dark, you could read by the light of a glowing plant on your desk.
MIT engineers have taken a critical first step toward making that vision a reality. By embedding specialized nanoparticles into the leaves of a watercress plant, they induced the plants to give off dim light for nearly four hours. They believe that, with further optimization, such plants will one day be bright enough to illuminate a workspace.
“The vision is to make a plant that will function as a desk lamp — a lamp that you don’t have to plug in. The light is ultimately powered by the energy metabolism of the plant itself,” says Michael Strano, the Carbon P. Dubbs Professor of Chemical Engineering at MIT and the senior author of the study.
This technology could also be used to provide low-intensity indoor lighting, or to transform trees into self-powered streetlights, the researchers say. MIT postdoc Seon-Yeong Kwak is the lead author of the study, which appears in the journal Nano Letters.
Plant nanobionics, a new research area pioneered by Strano’s lab, aims to give plants novel features by embedding them with different types of nanoparticles. The group’s goal is to engineer plants to take over many of the functions now performed by electrical devices. The researchers have previously designed plants that can detect explosives and communicate that information to a smartphone, as well as plants that can monitor drought conditions.
Lighting, which accounts for about 20 percent of worldwide energy consumption, seemed like a logical next target. “Plants can self-repair, they have their own energy, and they are already adapted to the outdoor environment,” Strano says. “We think this is an idea whose time has come. It’s a perfect problem for plant nanobionics.”
To create their glowing plants, the MIT team turned to luciferase, the enzyme that gives fireflies their glow. Luciferase acts on a molecule called luciferin, causing it to emit light. Another molecule called co-enzyme A helps the process along by removing a reaction byproduct that can inhibit luciferase activity.
The MIT team packaged each of these three components into a different type of nanoparticle carrier. The nanoparticles, which are all made of materials that the U.S. Food and Drug Administration classifies as “generally regarded as safe,” help each component get to the right part of the plant. They also prevent the components from reaching concentrations that could be toxic to the plants.
The researchers used silica nanoparticles about 10 nanometers in diameter to carry luciferase, and they used slightly larger particles of the polymers PLGA and chitosan to carry luciferin and coenzyme A, respectively. To get the particles into plant leaves, the researchers first suspended the particles in a solution. Plants were immersed in the solution and then exposed to high pressure, allowing the particles to enter the leaves through tiny pores called stomata.
Particles releasing luciferin and coenzyme A were designed to accumulate in the extracellular space of the mesophyll, an inner layer of the leaf, while the smaller particles carrying luciferase enter the cells that make up the mesophyll. The PLGA particles gradually release luciferin, which then enters the plant cells, where luciferase performs the chemical reaction that makes luciferin glow.
Video: Melanie Gonick/MIT
The researchers’ early efforts at the start of the project yielded plants that could glow for about 45 minutes, which they have since improved to 3.5 hours. The light generated by one 10-centimeter watercress seedling is currently about one-thousandth of the amount needed to read by, but the researchers believe they can boost the light emitted, as well as the duration of light, by further optimizing the concentration and release rates of the components.
Previous efforts to create light-emitting plants have relied on genetically engineering plants to express the gene for luciferase, but this is a laborious process that yields extremely dim light. Those studies were performed on tobacco plants and Arabidopsis thaliana, which are commonly used for plant genetic studies. However, the method developed by Strano’s lab could be used on any type of plant. So far, they have demonstrated it with arugula, kale, and spinach, in addition to watercress.
For future versions of this technology, the researchers hope to develop a way to paint or spray the nanoparticles onto plant leaves, which could make it possible to transform trees and other large plants into light sources.
“Our target is to perform one treatment when the plant is a seedling or a mature plant, and have it last for the lifetime of the plant,” Strano says. “Our work very seriously opens up the doorway to streetlamps that are nothing but treated trees, and to indirect lighting around homes.”
The researchers have also demonstrated that they can turn the light off by adding nanoparticles carrying a luciferase inhibitor. This could enable them to eventually create plants that shut off their light emission in response to environmental conditions such as sunlight, the researchers say.
The research was funded by the U.S. Department of Energy.
Anne Trafton | MIT News Office
December 12, 2017
|MIT Institute Professor John Deutch. Photo, Donna Coveney|
MIT Institute Professor John Deutch, who has been on the MIT faculty since 1970, has served as a department head, dean of the School of Science, and provost, and has published over 160 technical publications as well as numerous publications on technology, energy, international security, and public policy issues. He served in the U.S. government as director of central intelligence from 1995 to 1996, as deputy secretary of defense from 1994 to 1995, and in other posts in the departments of Defense and Energy. He is a member of the nonpartisan Aspen Strategy Group, which is composed of current and former policymakers, academics, journalists, and business leaders whose aim is to explore foreign policy and national security challenges facing the United States. The group has just released its annual report, and it includes a chapter co-written by Deutch and former U.S. Secretary of State Condoleezza Rice, about how the U.S. should deal with the risk of losing important intellectual property rights regarding technological innovations, in the face of efforts by China to acquire such technology through underhanded means. MIT News asked Deutch to describe the potential risks and remedies for such actions that he and Rice outlined in their report.
Q: What was the challenge that you and Prof. Rice, now at Stanford Business School, were asked to address in this piece, and what conclusions did you reach?
A: This year the subject [of the Aspen Strategy Group’s annual report] was the future challenges we see for policy. There was a lot of talk about China and what its relationship with the United States is likely to be, and in the course of this there was a lot of discussion about national security and the tremendous emphasis in China's new five-year plan on technology, in key areas such as robotics, artificial intelligence, and machine learning. There also was a great deal of discussion about nefarious activities by some in China, including trying to get certain Chinese nationals who live here to provide information to the Chinese government to help them acquire this advanced technology. As a result of that, there's been a hint of a new set of proposals from some elements of the natonal security community to, first, control information in the United States from leaving the country, and, second, restrict Chinese nationals from participating in certain kinds of research projects. Condi and I decided to write a short piece about the danger of these proposals.
Basically our view was, yes, the Chinese are putting a greater emphasis on technology; they are growing very fast and they're increasingly competent, and so we should expect greater competition. And yes, they are performing illegal acts against the U.S., especially theft of intellectual property. The U.S. should do everything it can to push back on that effort and prevent it if possible. But the idea that we should respond to this threat by either restricting access to U.S. universities or keeping our ideas in the United States is completely wrong. We'll lose the tremendous advantage we have of an open university system if we do that. The only answer is for U.S. universities to do even more in pursuing their great record of being innovative and creative.
Q: Do you think it's possible to maintain academic freedom of information in the context of dealing with people who may not share our commitment to protecting intellectual property?
A: In such a situation, we need to recognize that we will have some losses. But there will be more severe effects on our innovative enterprise, which is the best in the world, if we start trying to stop these losses by applying restrictions. Universities aren't very good, first of all, at assessing the nature of the risk [of intellectual-property loss] and, second, at deciding what restrictive measures should be put in place. So, both my co-author Condi and I believe, keep the system open. Recognize that you will have some losses, but do what you do well.
Universities should make sure that our scholarly efforts and our educational efforts permit advances in key areas where fundamental research and practical application come together, in health, energy, and environment, including an emphasis on innovation. And we see that happening. By the way, much as the Chinese universities are improving, they do not have the kind of ecosystem that is so strong here, in terms of promoting innovation, creativity, and getting important things implemented in the private sector.
Q: So are there specific measures that universities should be taking to address these efforts to exploit U.S. innovations, or is your advice that they should avoid taking any special measures?
A: My answer is no, there are not specific measures they should take, but it is very important that the administrative leadership of the university understands the concerns in Washington, appreciates the risks, and doesn’t enter into joint projects that could really lead to a loss of sensitive technology.
The universities should try and explain to the government that we think the proper response here is better performance by U.S. universities, rather than trying to keep people out or keep our ideas in.
I think one should expect that the technical competence of China will continue to improve, because of the capabilities of its people and the significant amount of resources the Chinese are putting into technology leadership in a variety of fields. We should expect that. How much of an advantage is given to China by their quite sustained illegal efforts to acquire technology from both the United States and Europe? I think it is helpful but by no means the most important or the determining factor in their advance.
This short piece with Condi Rice is not so much directed to U.S. universities; rather it is directed to the government and the national security community, to say to them, be cautious here — don't throw the baby out with the bathwater.
David L. Chandler | MIT News Office
December 15, 2017
|Schwarzman Scholars from top left, clockwise: Katheryn Scott, Han Wu, Henry Aspegren, Joshua Woodard. Images courtesy of Schwarzman Scholars. Images courtesy of Schwarzman Scholars.|
Three MIT students — Henry Aspegren '17, Katheryn Scott, and Joshua Woodard — were selected as Schwarzman Scholars and will begin postgraduate studies at Tsinghua University in Beijing next fall. An alumnus, Han Wu MEng '15, was also selected for this highly competitive program.
Schwarzman Scholars are chosen based on demonstrated leadership qualities and potential to bridge and understand cultural and political differences. They will live in Beijing for a year of study and cultural immersion, attending lectures, traveling, and developing a better understanding of China.
This year’s four Schwarzman Scholars bring to 11 the total number of MIT winners honored since the scholarship’s inception in 2015. In all, 142 Schwarzman Scholars were selected from over 4,000 applicants. The new class is comprised of students from 39 countries and 97 universities with 41 percent from the United States, 20 percent from China, and 39 percent from the rest of the world. The currently enrolled MIT students were supported by MIT’s Office of Distinguished Fellowships the Presidential Committee on Distinguished Fellowships.
“This year’s winners of the Schwarzman Scholarship exemplify the combination of intellectual prowess and public mindedness that characterizes MIT students at their best,” says Professor William Broadhead, co-chair of the Presidential Committee for Distinguished Fellowships alongside Professor Rebecca Saxe. “Those of us who have had the pleasure of working with them through the application process have been impressed at every turn by their immense potential for local and global leadership. It’s exciting to celebrate with them now; and it will be exciting to see what they do next!”
Henry Aspegren, from Ann Arbor, Michigan, is an MIT master’s student in engineering. He received his BS in electrical engineering and computer science from MIT earlier this year. Aspegren aspires to develop public policy for addressing the new challenges and opportunities created by technology.
Aspegren recognized the economic disparities of the Detroit area growing up, when he played ice hockey on a team with players from manufacturing towns around metro Detroit that had been hit hard by the decline of the auto industry. This reality drew him to think about how economic incentives can stimulate economies, which fueled his academic interests in currency and financial institutions.
At MIT, Aspegren began conducting research in the MIT Media Lab’s Viral Communications Group, where he worked to help build a voting and ranking algorithm to quantify subjective qualities such as emotion across the internet in real time. During his junior year, he participated in the Cambridge MIT Exchange program and received a first from Cambridge University and a full blue in ice hockey.
This past January, Aspegren traveled to Korea through the MIT International Science and Technology Initiatives' Global Teaching Laboratory to lead a robotics workshop in which students programmed a Roomba vaccum cleaner to drive around an obstacle course. He has also interned with the electronic trading team at Goldman Sachs in New York and London, and worked as a software engineer with BetterWorks in Palo Alto.
Aspegren is now completing his MEng degree and conducting research with the MIT Media Lab’s Digital Currency Initiative to examine injustices in financing. This led him to design a block chain-based system for agricultural financing in Latin America in collaboration with the InterAmerican Development Bank.
Aspegren has been an active participant in MIT Athletics, playing club ice hockey throughout his undergraduate and graduate career, and playing on the varsity lacrosse team his freshman year. He is also a brother of Theta Chi Fraternity.
Katheryn "Kate" Scott, from Barrington, Illinois, is an MIT senior majoring in materials science and engineering. She studied abroad at Oxford University in her junior year through the Department of Materials Science and Engineering’s exchange program. Scott seeks to pursue a future career bridging the gap between science and communications, and eventually plans to found her own communications firm.
In the summer of her freshman year, Scott traveled to Singapore to conduct materials research, fabricating thin-film membranes to create nano-filtration systems for smog. She later began research with the MIT Libraries Conservation Lab, prototyping two different devices for reversible flattening of manuscripts, which would automate part of the conservation process. At Oxford, Scott conducted polymer research with the Polymer Group and Ashmolean Museum.
Scott has a keen interest in industry, and worked as a chemical engineering intern at Honeywell UOP. While there, she worked to improve wastewater filtration by developing a disinfectant and low temperature tolerant bacteria. The system saves 400,000 gallons of wastewater per day, results that led to the adoption of her system in October 2016.
Scott is a sorority sister of Sigma Kappa, and has held the role of continuing membership chair and new member assistant coordinator. She was elected as vice president of programming for the MIT Panhellenic Association.
Since Scott’s freshman year, she has been a member of MIT’s only Division I sport, rowing. She and her boat earned a bid to the 2016 national competition, and placed 5th, and Scott was named a Collegiate Rowing Coaches Association Scholar Athlete. When she was at Oxford University, she joined the university’s lightweight rowing club.
Joshua Charles Woodard, from Chicago, Illinois, is an MIT senior majoring in mechanical engineering with a minor in Mandarin Chinese. At Tsinghua, Woodard will earn a degree in politics, with a focus on comparative government. He plans a future career in diplomacy and public policy, with the goal of enacting effective strategies for social change.
Woodard’s dedication to social justice issues began prior to arriving at MIT. As a junior in high school, he applied for and was granted a Boeing Scholars Academy award to research Chicago’s gun violence and devise solutions. He then coordinated a city-wide brainstorming event between youth and government officials.
At MIT, Woodard has been a pivotal voice on issues of diversity and inclusion. As a student advisor on MIT President L. Rafael Reif’s Presidential Advisory Committee, he has provided guidance on important campus issues and policies ranging from diversity initiatives to the influence of the current political climate. Woodard has also demonstrated his leadership skills as co-chair of the student community and living group Chocolate City, and has been instrumental in increasing campus awareness of the Black Lives Matter movement and creating opportunities for dialogue.
Woodard participated in the Internationally Genetically Engineered Machines (iGEM) worldwide competition for synthetic biology, and he has interned in industrial design at the Charles Stark Draper Laboratory and HTC. He has also advocated to help local Boston high school students from underrepresented communities gain access to STEM experiences by co-founding the summer leadership program MIT BoSTEM Scholars Academy.
A talented artist and musician, Woodard has studied and performed Beijing Opera at the Shanghai Theater Academy in China, runs his own freelance photography business, JC Woodard Photography, and has performed on violin and viola with the MIT Jazz Band.
Han Wu graduated from MIT in 2015 with a master's degree in structural engineering focusing on high performance structures.
Prior to enrolling at MIT, he received a bachelor’s degree from the University of California at Los Angeles majoring in civil and environmental engineering and minoring in accounting. Currently, he works at Ove Arup and Partners Hong Kong (one of the worldwide leading engineering consulting firms) as a structural engineer and the chairman of Young Engineer’s Group.
Besides tackling challenging design problems, Wu also plays a key role in researching and implementing industry leading design tools as well as conducting training sessions. Upon completion of Schwarzman Scholars, he hopes to pursue a career in which he can combine his experience and knowledge in design and business development.
Kim Benard | Office of Distinguished Fellowships
MIT News Office
December 4, 2017
|BASF and Volkswagen Science Award Electrochemistry presentation Dec. 1, 2017, at Karlsruhe Institute of Technology in Germany. Standing (l-r): Volkswagen AG Research and Development Group Head Ulrich Eichhorn, Catalytic Innovations founder and CEO Stafford Sheehan, who received a special prize for applied research MIT Assistant Professor of Materials Science and Engineering Jennifer Rupp, who received the Science Award Electrochemistry, BASF Chief Technology Officer and Vice Chairman of the Board of Executive Directors Martin Brudermüller, and Karlsruhe Institute of Technology President Holger Hanselka. BASF photo.|
Jennifer L. M. Rupp, who holds joint appointments at MIT as an assistant professor in the Departments of Materials Science and Engineering [DMSE] and Electrical Engineering and Computer Science [EECS], won the 2017 “Science Award Electrochemistry,” awarded by Volkswagen and BASF. Rupp was honored for her work on energy storage systems.
Rupp received the award, which is worth about $47,000, on Dec. 1, 2017, at ceremonies held at Karlsruhe Institute of Technology (KIT) in Germany. Rupp’s Electrochemical Materials Laboratory at MIT is working to replace the flammable liquid electrolyte in lithium batteries with a safer solid-state lithium electrolyte.
“The team was honored to receive the award for their work on processing and designing new solid-state, garnet-type batteries and for their commitment to integrate cathodes with socio-economically acceptable elements," Rupp says. “Designing lithium conducting glass-ceramics and battery electrode alloys can be interesting strategies for future battery architectures based on garnets to avoid lithium dendrites that often lead to performance failure," Rupp says. Dendrites are lithium filaments shaped like tree leaves or snowflakes that can form in rechargeable lithium metal batteries, and their unchecked growth can cause a cell to short-circuit.
“The winners of our Science Award are an excellent example of innovative and creative ideas in this field,” says Dr. Ulrich Eichhorn, head of Group Research and Development for Volkswagen AG. The German automaker plans to reach a goal of 25 percent battery-powered electric vehicles by 2025.
The Science Award Electrochemistry noted Rupp’s work on ceramic engineering for fast lithium transfer in garnet-type batteries and a novel glassy-type lithium ion conductor that may lead to new design principles for solid-state batteries. “BASF creates chemistry for a sustainable future. We all know that batteries are at the core of electromobility, and there is great potential for specific technological progress in this area. Yet, there are scientific hurdles we must first overcome,” says Martin Brudermüller, Vice Chairman of the Board of Executive Directors and Chief Technology Officer at BASF. “Electrochemistry is a key technology for sustainable future mobility. That is why we need first-class research around the globe conducted by excellent scientists who inspire each other to continuously develop new and better solutions.”
Rupp joined the MIT Department of Materials Science and Engineering in January 2017 as the Thomas Lord Assistant Professor of Materials Science and Engineering at MIT, and recently was appointed as an assistant professor in the Department of Electrical Engineering and Computer Science. She also conducts research on materials for solid oxide fuel cells, electrochemical sensors and information storage devices.
The BASF and Volkswagen International “Science Award Electrochemistry” has been awarded yearly since 2012.
– Materials Research Laboratory
December 19, 2017
|Community college students who experience a summer of research at MIT develop greater self-confidence and better academic skills, with a majority completing a four-year degree, MIT Materials Research Laboratory Education Officer Susan Rosevear told a symposium at the Materials Research Society Fall meeting in Boston on Monday, Nov. 27, 2017. Photo, Denis Paiste, MIT MRL|
A summer of research at MIT gives inner-city Boston community college students a pathway toward greater self-confidence, better academic skills and a four-year college degree, MIT Materials Research Laboratory Education Officer Susan Rosevear said Monday, Nov. 27, 2017, during a symposium at the Materials Research Society [MRS] Fall meeting in Boston.
“Many of them have barely heard about materials science when they come to MIT, and by the end of the summer, they get sort of a full dunk into the world of materials science, so they are better informed to go forward,” Rosevear says. Over the past dozen years, 63 students from Roxbury and Bunker Hill Community Colleges have participated in the program at MIT. Of these, 45 went on to earn a four-year degree, with 34 pursuing degrees in science or engineering. Five continued on to graduate school in science or medicine.
The Research Experience for Undergraduates (REU) program is primarily funded through the MIT Materials Research Laboratory’s National Science Foundation-funded Materials Research Science and Engineering Center [NSF-MRSEC]. Bringing in underrepresented, or non-traditional, students from the community colleges broadens the diversity of students in the REU program.
“We are trying, and I think succeeding, in providing opportunities to community college students that they don’t have at their home institutions,” Rosevear says. Students learn to use electron microscopes, X-ray diffraction spectrometers and other advanced materials science characterization tools. Rosevear addressed a session at MRS highlighting collaborations between community colleges and four-year colleges.
In 2005, the MIT MRSEC, then part of the Center for Materials Science and Engineering, began the partnership with Roxbury Community College with seven students participating during its first year. In recent years, the summer program expanded to include community college professors in materials research on campus led by MIT faculty. So far, nine community college professors have participated. CMSE merged in October 2017 with the Materials Processing Center to form the MIT Materials Research Laboratory.
During the fall 2017 semester, Roxbury Community College Chemistry and Biotechnology Professor Kimberly Stieglitz offered a new course at Roxbury Community College, Research Science, [SCI 281] that brought students to the X-ray diffraction facility at MIT to examine their lab samples. “We keep finding new ways to leverage this partnership,” Rosevear says. Stieglitz and other teachers who have participated in the summer teachers’ program at MIT, also have incorporated material from their summer research into their classroom teaching, Rosevear notes.
Students must complete a basic engineering or science course, such as chemistry or biology, to be accepted into the MIT summer program. Community college teachers select the students based on academic record, statements of interest and faculty letters of recommendation. “They’ve been great partners for us, which is really key to the whole thing,” Rosevear explains. “Kimberly [Stieglitz] has told me, once they are selected, just knowing they are going to MIT changes their performance, they become more serious about themselves, their performance, motivation increases, and they have an increased commitment to STEM,” Rosevear says.
|Roxbury Community College Chemistry and Biotechnology Professor Kimberly Stieglitz [left] discusses her summer research at MIT with JoDe M. Lavine, Bunker Hill Community College Professor and Chairperson of the Engineering & Physical Sciences Department, during the annual Summer Scholars Poster Session on Aug. 3, 2017. Stieglitz worked in the lab of AMAX Career Development Assistant Professor in Materials Science and Engineering Robert J. Macfarlane. Photo, Denis Paiste, MIT MRL.|
Over the course of the summer, community college students attend weekly luncheon meetings covering topics such as crafting a high-quality poster presentation, applying to graduate school, understanding patents and trademarks, and pursuing careers in materials science and other engineering fields.
Interest among MIT faculty in hosting community college students continues to grow. “I have people coming to me and say, how do I get one of these students?
The students have sold themselves, is essentially what’s happened,” Rosevear says.
The community college program is distinct from the Summer Scholars program, which is open to undergraduates in science and engineering from across the U.S. and Puerto Rico who are citizens or legal residents. Applications for summer 2018 must be submitted by Feb. 16, 2018.
– Denis Paiste, MIT Materials Research Laboratory
December 19, 2017
|MIT engineers have devised a 3-D printing technique that uses a new kind of ink made from genetically programmed living cells. Courtesy of the researchers|
MIT engineers have devised a 3-D printing technique that uses a new kind of ink made from genetically programmed living cells.
The cells are engineered to light up in response to a variety of stimuli. When mixed with a slurry of hydrogel and nutrients, the cells can be printed, layer by layer, to form three-dimensional, interactive structures and devices.
The team has then demonstrated its technique by printing a “living tattoo” — a thin, transparent patch patterned with live bacteria cells in the shape of a tree. Each branch of the tree is lined with cells sensitive to a different chemical or molecular compound. When the patch is adhered to skin that has been exposed to the same compounds, corresponding regions of the tree light up in response.
The researchers, led by Xuanhe Zhao, the Noyce Career Development Professor in MIT’s Department of Mechanical Engineering, and Timothy Lu, associate professor of biological engineering and of electrical engineering and computer science, say that their technique can be used to fabricate “active” materials for wearable sensors and interactive displays. Such materials can be patterned with live cells engineered to sense environmental chemicals and pollutants as well as changes in pH and temperature.
What’s more, the team developed a model to predict the interactions between cells within a given 3-D-printed structure, under a variety of conditions. The team says researchers can use the model as a guide in designing responsive living materials.
Zhao, Lu, and their colleagues have published their results Dec. 5, 2017, in the journal Advanced Materials. The paper’s co-authors are graduate students Xinyue Liu, Hyunwoo Yuk, Shaoting Lin, German Alberto Parada, Tzu-Chieh Tang, Eléonore Tham, and postdoc Cesar de la Fuente-Nunez.
A hardy alternative
In recent years, scientists have explored a variety of responsive materials as the basis for 3D-printed inks. For instance, scientists have used inks made from temperature-sensitive polymers to print heat-responsive shape-shifting objects. Others have printed photoactivated structures from polymers that shrink and stretch in response to light.
Zhao’s team, working with bioengineers in Lu’s lab, realized that live cells might also serve as responsive materials for 3D-printed inks, particularly as they can be genetically engineered to respond to a variety of stimuli. The researchers are not the first to consider 3-D printing genetically engineered cells; others have attempted to do so using live mammalian cells, but with little success.
“It turns out those cells were dying during the printing process, because mammalian cells are basically lipid bilayer balloons,” Yuk says. “They are too weak, and they easily rupture.”
Instead, the team identified a hardier cell type in bacteria. Bacterial cells have tough cell walls that are able to survive relatively harsh conditions, such as the forces applied to ink as it is pushed through a printer’s nozzle. Furthermore, bacteria, unlike mammalian cells, are compatible with most hydrogels — gel-like materials that are made from a mix of mostly water and a bit of polymer. The group found that hydrogels can provide an aqueous environment that can support living bacteria.
The researchers carried out a screening test to identify the type of hydrogel that would best host bacterial cells. After an extensive search, a hydrogel with pluronic acid was found to be the most compatible material. The hydrogel also exhibited an ideal consistency for 3-D printing.
“This hydrogel has ideal flow characteristics for printing through a nozzle,” Zhao says. “It’s like squeezing out toothpaste. You need [the ink] to flow out of a nozzle like toothpaste, and it can maintain its shape after it’s printed
Video Abstract for Advanced Materials, 2017, 29, 1704821. Reproduced with permission. ©2017, Wiley-VCH Verlag GmbH & Co. KGaA.
From tattoos to living computers
Lu provided the team with bacterial cells engineered to light up in response to a variety of chemical stimuli. The researchers then came up with a recipe for their 3-D ink, using a combination of bacteria, hydrogel, and nutrients to sustain the cells and maintain their functionality. “We found this new ink formula works very well and can print at a high resolution of about 30 micrometers per feature,” Zhao says. “That means each line we print contains only a few cells. We can also print relatively large-scale structures, measuring several centimeters.”
They printed the ink using a custom 3-D printer that they built using standard elements combined with fixtures they machined themselves. To demonstrate the technique, the team printed a pattern of hydrogel with cells in the shape of a tree on an elastomer layer. After printing, they solidified, or cured, the patch by exposing it to ultraviolet radiation. They then adhere the transparent elastomer layer with the living patterns on it, to skin.
To test the patch, the researchers smeared several chemical compounds onto the back of a test subject’s hand, then pressed the hydrogel patch over the exposed skin. Over several hours, branches of the patch’s tree lit up when bacteria sensed their corresponding chemical stimuli. The researchers also engineered bacteria to communicate with each other; for instance they programmed some cells to light up only when they receive a certain signal from another cell. To test this type of communication in a 3-D structure, they printed a thin sheet of hydrogel filaments with “input,” or signal-producing bacteria and chemicals, overlaid with another layer of filaments of an “output,” or signal-receiving bacteria. They found the output filaments lit up only when they overlapped and received input signals from corresponding bacteria .
Yuk says in the future, researchers may use the team’s technique to print “living computers” — structures with multiple types of cells that communicate with each other, passing signals back and forth, much like transistors on a microchip. “This is very future work, but we expect to be able to print living computational platforms that could be wearable,” Yuk says.
For more near-term applications, the researchers are aiming to fabricate customized sensors, in the form of flexible patches and stickers that could be engineered to detect a variety of chemical and molecular compounds. They also envision their technique may be used to manufacture drug capsules and surgical implants, containing cells engineered produce compounds such as glucose, to be released therapeutically over time.
“We can use bacterial cells like workers in a 3-D factory,” Liu says. “They can be engineered to produce drugs within a 3-D scaffold, and applications should not be confined to epidermal devices. As long as the fabrication method and approach are viable, applications such as implants and ingestibles should be possible.”
This research was supported, in part, by the Office of Naval Research, National Science Foundation, National Institutes of Health, and MIT Institute for Soldier Nanotechnologies.
Jennifer Chu | MIT News Office
December 5, 2017