Nanoscience and nanotechnology

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      in Environment

      Nanotube sensors are capable of detecting and distinguishing gibberellin plant hormones

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      Researchers from the Disruptive and Sustainable Technologies for Agricultural Precision (DiSTAP) interdisciplinary research group of the Singapore-MIT Alliance for Research and Technology (SMART), MIT’s research enterprise in Singapore, and their collaborators from Temasek Life Sciences Laboratory have developed the first-ever nanosensor that can detect and distinguish gibberellins (GAs), a class of hormones in plants that are important for growth. The novel nanosensors are nondestructive, unlike conventional collection methods, and have been successfully tested in living plants. Applied in the field for early-stage plant stress monitoring, the sensors could prove transformative for agriculture and plant biotechnology, giving farmers interested in high-tech precision agriculture and crop management a valuable tool to optimize yield.

      The researchers designed near-infrared fluorescent carbon nanotube sensors that are capable of detecting and distinguishing two plant hormones, GA3 and GA4. Belonging to a class of plant hormones known as gibberellins, GA3 and GA4 are diterpenoid phytohormones produced by plants that play an important role in modulating diverse processes involved in plant growth and development. GAs are thought to have played a role in the driving forces behind the “green revolution” of the 1960s, which was in turn credited with averting famine and saving the lives of many worldwide. The continued study of gibberellins could lead to further breakthroughs in agricultural science and have implications for food security.

      Climate change, global warming, and rising sea levels cause farming soil to get contaminated by saltwater, raising soil salinity. In turn, high soil salinity is known to negatively regulate GA biosynthesis and promote GA metabolism, resulting in the reduction of GA content in plants. The new nanosensors developed by the SMART researchers allow for the study of GA dynamics in living plants under salinity stress at a very early stage, potentially enabling farmers to make early interventions when eventually applied in the field. This forms the basis of early-stage stress detection.

      Currently, methods to detect GA3 and GA4 typically require mass spectroscopy-based analysis, a time-consuming and destructive process. In contrast, the new sensors developed by the researchers are highly selective for the respective GAs and offer real-time, in vivo monitoring of changes in GA levels across a broad range of plant species.

      Described in a paper titled “Near-Infrared Fluorescent Carbon Nanotube Sensors for the Plant Hormone Family Gibberellins” published in the journal Nano Letters, the research represents a breakthrough for early-stage plant stress detection and holds tremendous potential to advance plant biotechnology and agriculture. This paper builds on previous research by the team at SMART DiSTAP on single-walled carbon nanotube-based nanosensors using the corona phase molecular recognition (CoPhMoRe) platform.

      Based on the CoPhMoRe concept introduced by the lab of MIT Professor Professor Michael Strano, the novel sensors are able to detect GA kinetics in the roots of a variety of model and non-model plant species, including Arabidopsis, lettuce, and basil, as well as GA accumulation during lateral root emergence, highlighting the importance of GA in root system architecture. This was made possible by the researchers’ related development of a new coupled Raman/near infrared fluorimeter that enables self-referencing of nanosensor near infrared fluorescence with its Raman G-band, a new hardware innovation that removes the need for a separate reference nanosensor and greatly simplifies the instrumentation requirements by using a single optical channel to measure hormone concentration.

      Using the reversible GA nanosensors, the researchers detected increased endogenous GA levels in mutant plants producing greater amounts of GA20ox1, a key enzyme in GA biosynthesis, as well as decreased GA levels in plants under salinity stress. When exposed to salinity stress, researchers also found that lettuce growth was severely stunted — an indication that only became apparent after 10 days. In contrast, the GA nanosensors reported decreased GA levels after just six hours, demonstrating their efficacy as a much earlier indicator of salinity stress.

      “Our CoPhMoRe technique allows us to create nanoparticles that act like natural antibodies in that they can recognize and lock onto specific molecules. But they tend to be far more stable than alternatives. We have used this method to successfully create nanosensors for plant signals such as hydrogen peroxide and heavy-metal pollutants like arsenic in plants and soil,” says Strano, the Carbon P. Dubbs Professor of Chemical Engineering at MIT who is co-corresponding author and DiSTAP co-lead principal investigator. “The method works to create sensors for organic molecules like synthetic auxin — an important plant hormone — as we have shown. This latest breakthrough now extends this success to a plant hormone family called gibberellins — an exceedingly difficult one to recognize.”

      Strano adds: “The resulting technology offers a rapid, real-time, and in vivo method to monitor changes in GA levels in virtually any plant, and can replace current sensing methods which are laborious, destructive, species-specific, and much less efficient.”

      Mervin Chun-Yi Ang, associate scientific director at DiSTAP and co-first author of the paper, says, “More than simply a breakthrough in plant stress detection, we have also demonstrated a hardware innovation in the form of a new coupled Raman/NIR fluorimeter that enabled self-referencing of SWNT sensor fluorescence with its Raman G-band, representing a major advance in the translation of our nanosensing tool sets to the field. In the near future, our sensors can be combined with low-cost electronics, portable optodes, or microneedle interfaces for industrial use, transforming how the industry screens for and mitigates plant stress in food crops and potentially improving growth and yield.”

      The new sensors could yet have a variety of industrial applications and use cases. Daisuke Urano, a Temasek Life Sciences Laboratory principal investigator, National University of Singapore (NUS) adjunct assistant professor, and co-corresponding author of the paper, explains, “GAs are known to regulate a wide range of plant development processes, from shoot, root, and flower development, to seed germination and plant stress responses. With the commercialization of GAs, these plant hormones are also sold to growers and farmers as plant growth regulators to promote plant growth and seed germination. Our novel GA nanosensors could be applied in the field for early-stage plant stress monitoring, and also be used by growers and farmers to track the uptake or metabolism of GA in their crops.”

      The design and development of the nanosensors, creation and validation of the coupled Raman/near infrared fluorimeter and related image/data processing algorithms, as well as statistical analysis of readouts from plant sensors for this study were performed by SMART and MIT. The Temasek Life Sciences Laboratory was responsible for the design, execution, and analysis of plant-related studies, including validation of nanosensors in living plants.

      This research was carried out by SMART and supported by the National Research Foundation of Singapore under its Campus for Research Excellence And Technological Enterprise (CREATE) program. The DiSTAP program, led by Strano and Singapore co-lead principal investigator Professor Chua Nam Hai, addresses deep problems in food production in Singapore and the world by developing a suite of impactful and novel analytical, genetic, and biomaterial technologies. The goal is to fundamentally change how plant biosynthetic pathways are discovered, monitored, engineered, and ultimately translated to meet the global demand for food and nutrients. Scientists from MIT, Temasek Life Sciences Laboratory, Nanyang Technological University (NTU) and NUS are collaboratively developing new tools for the continuous measurement of important plant metabolites and hormones for novel discovery, deeper understanding and control of plant biosynthetic pathways in ways not yet possible, especially in the context of green leafy vegetables; leveraging these new techniques to engineer plants with highly desirable properties for global food security, including high yield density production, and drought and pathogen resistance, and applying these technologies to improve urban farming.

      SMART was established by MIT and the National Research Foundation of Singapore in 2007. SMART serves as an intellectual and innovation hub for research interactions between MIT and Singapore, undertaking cutting-edge research projects in areas of interest to both Singapore and MIT. SMART currently comprises an Innovation Center and five interdisciplinary research groups: Antimicrobial Resistance, Critical Analytics for Manufacturing Personalized-Medicine, DiSTAP, Future Urban Mobility, and Low Energy Electronic Systems. More

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      in Energy

      Strengthening electron-triggered light emission

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      The way electrons interact with photons of light is a key part of many modern technologies, from lasers to solar panels to LEDs. But the interaction is inherently a weak one because of a major mismatch in scale: A wavelength of visible light is about 1,000 times larger than an electron, so the way the two things affect each other is limited by that disparity.

      Now, researchers at MIT and elsewhere have come up with an innovative way to make much stronger interactions between photons and electrons possible, in the process producing a hundredfold increase in the emission of light from a phenomenon called Smith-Purcell radiation. The finding has potential implications for both commercial applications and fundamental scientific research, although it will require more years of research to make it practical.

      The findings are reported today in the journal Nature, in a paper by MIT postdocs Yi Yang (now an assistant professor at the University of Hong Kong) and Charles Roques-Carmes, MIT professors Marin Soljačić and John Joannopoulos, and five others at MIT, Harvard University, and Technion-Israel Institute of Technology.

      In a combination of computer simulations and laboratory experiments, the team found that using a beam of electrons in combination with a specially designed photonic crystal — a slab of silicon on an insulator, etched with an array of nanometer-scale holes — they could theoretically predict stronger emission by many orders of magnitude than would ordinarily be possible in conventional Smith-Purcell radiation. They also experimentally recorded a one hundredfold increase in radiation in their proof-of-concept measurements.

      Unlike other approaches to producing sources of light or other electromagnetic radiation, the free-electron-based method is fully tunable — it can produce emissions of any desired wavelength, simply by adjusting the size of the photonic structure and the speed of the electrons. This may make it especially valuable for making sources of emission at wavelengths that are difficult to produce efficiently, including terahertz waves, ultraviolet light, and X-rays.

      The team has so far demonstrated the hundredfold enhancement in emission using a repurposed electron microscope to function as an electron beam source. But they say that the basic principle involved could potentially enable far greater enhancements using devices specifically adapted for this function.

      The approach is based on a concept called flatbands, which have been widely explored in recent years for condensed matter physics and photonics but have never been applied to affecting the basic interaction of photons and free electrons. The underlying principle involves the transfer of momentum from the electron to a group of photons, or vice versa. Whereas conventional light-electron interactions rely on producing light at a single angle, the photonic crystal is tuned in such a way that it enables the production of a whole range of angles.

      The same process could also be used in the opposite direction, using resonant light waves to propel electrons, increasing their velocity in a way that could potentially be harnessed to build miniaturized particle accelerators on a chip. These might ultimately be able to perform some functions that currently require giant underground tunnels, such as the 30-kilometer-wide Large Hadron Collider in Switzerland.

      “If you could actually build electron accelerators on a chip,” Soljačić says, “you could make much more compact accelerators for some of the applications of interest, which would still produce very energetic electrons. That obviously would be huge. For many applications, you wouldn’t have to build these huge facilities.”

      The new system could also potentially provide a highly controllable X-ray beam for radiotherapy purposes, Roques-Carmes says.

      And the system could be used to generate multiple entangled photons, a quantum effect that could be useful in the creation of quantum-based computational and communications systems, the researchers say. “You can use electrons to couple many photons together, which is a considerably hard problem if using a purely optical approach,” says Yang. “That is one of the most exciting future directions of our work.”

      Much work remains to translate these new findings into practical devices, Soljačić cautions. It may take some years to develop the necessary interfaces between the optical and electronic components and how to connect them on a single chip, and to develop the necessary on-chip electron source producing a continuous wavefront, among other challenges.

      “The reason this is exciting,” Roques-Carmes adds, “is because this is quite a different type of source.” While most technologies for generating light are restricted to very specific ranges of color or wavelength, and “it’s usually difficult to move that emission frequency. Here it’s completely tunable. Simply by changing the velocity of the electrons, you can change the emission frequency. … That excites us about the potential of these sources. Because they’re different, they offer new types of opportunities.”

      But, Soljačić concludes, “in order for them to become truly competitive with other types of sources, I think it will require some more years of research. I would say that with some serious effort, in two to five years they might start competing in at least some areas of radiation.”

      The research team also included Steven Kooi at MIT’s Institute for Soldier Nanotechnologies, Haoning Tang and Eric Mazur at Harvard University, Justin Beroz at MIT, and Ido Kaminer at Technion-Israel Institute of Technology. The work was supported by the U.S. Army Research Office through the Institute for Soldier Nanotechnologies, the U.S. Air Force Office of Scientific Research, and the U.S. Office of Naval Research. More

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      in Energy

      In nanotube science, is boron nitride the new carbon?

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      Engineers at MIT and the University of Tokyo have produced centimeter-scale structures, large enough for the eye to see, that are packed with hundreds of billions of hollow aligned fibers, or nanotubes, made from hexagonal boron nitride.

      Hexagonal boron nitride, or hBN, is a single-atom-thin material that has been coined “white graphene” for its transparent appearance and its similarity to carbon-based graphene in molecular structure and strength. It can also withstand higher temperatures than graphene, and is electrically insulating, rather than conductive. When hBN is rolled into nanometer-scale tubes, or nanotubes, its exceptional properties are significantly enhanced.

      The team’s results, published today in the journal ACS Nano, provide a route toward fabricating aligned boron nitride nanotubes (A-BNNTs) in bulk. The researchers plan to harness the technique to fabricate bulk-scale arrays of these nanotubes, which can then be combined with other materials to make stronger, more heat-resistant composites, for instance to shield space structures and hypersonic aircraft.

      As hBN is transparent and electrically insulating, the team also envisions incorporating the BNNTs into transparent windows and using them to electrically insulate sensors within electronic devices. The team is also investigating ways to weave the nanofibers into membranes for water filtration and for “blue energy” — a concept for renewable energy in which electricity is produced from the ionic filtering of salt water into fresh water.

      Brian Wardle, professor of aeronautics and astronautics at MIT, likens the team’s results to scientists’ decades-long, ongoing pursuit of manufacturing bulk-scale carbon nanotubes.

      “In 1991, a single carbon nanotube was identified as an interesting thing, but it’s been 30 years getting to bulk aligned carbon nanotubes, and the world’s not even fully there yet,” Wardle says. “With the work we’re doing, we’ve just short-circuited about 20 years in getting to bulk-scale versions of aligned boron nitride nanotubes.”

      Wardle is the senior author of the new study, which includes lead author and MIT research scientist Luiz Acauan, former MIT postdoc Haozhe Wang, and collaborators at the University of Tokyo.

      A vision, aligned

      Like graphene, hexagonal boron nitride has a molecular structure resembling chicken wire. In graphene, this chicken wire configuration is made entirely of carbon atoms, arranged in a repeating pattern of hexagons. For hBN, the hexagons are composed of alternating atoms of boron and nitrogen. In recent years, researchers have found that two-dimensional sheets of hBN exhibit exceptional properties of strength, stiffness, and resilience at high temperatures. When sheets of hBN are rolled into nanotube form, these properties are further enhanced, particularly when the nanotubes are aligned, like tiny trees in a densely packed forest.

      But finding ways to synthesize stable, high quality BNNTs has proven challenging. A handful of efforts to do so have produced low-quality, nonaligned fibers.

      “If you can align them, you have much better chance of harnessing BNNTs properties at the bulk scale to make actual physical devices, composites, and membranes,” Wardle says.

      In 2020, Rong Xiang and colleagues at the University of Tokyo found they could produce high-quality boron nitride nanotubes by first using a conventional approach of chemical vapor deposition to grow a forest of short, few micron-long carbon nanotubes. They then coated the carbon-based forest with “precursors” of boron and nitrogen gas, which when baked in an oven at high temperatures crystallized onto the carbon nanotubes to form high-quality nanotubes of hexagonal boron nitride with carbon nanotubes inside.

      Burning scaffolds

      In the new study, Wardle and Acauan have extend and scale Xiang’s approach, essentially removing the underlying carbon nanotubes and leaving the long boron nitride nanotubes to stand on their own. The team drew on the expertise of Wardle’s group, which has focused for years on fabricating high-quality aligned arrays of carbon nanotubes. With their current work, the researchers looked for ways to tweak the temperatures and pressures of the chemical vapor deposition process in order to remove the carbon nanotubes while leaving the boron nitride nanotubes intact.

      “The first few times we did it, it was completely ugly garbage,” Wardle recalls. “The tubes curled up into a ball, and they didn’t work.”

      Eventually, the team hit on a combination of temperatures, pressures, and precursors that did the trick. With this combination of processes, the researchers first reproduced the steps that Xiang took to synthesize the boron-nitride-coated carbon nanotubes. As hBN is resistant to higher temperatures than graphene, the team then cranked up the heat to burn away the underlying black carbon nanotube scaffold, while leaving the transparent, freestanding boron nitride nanotubes intact.
      By using carbon nanotubes as a scaffold, MIT engineers grow forests of “white graphene” that emerge (in MIT pattern) after burning away the black carbon scaffold. Courtesy of the researchersIn microscopic images, the team observed clear crystalline structures — evidence that the boron nitride nanotubes have a high quality. The structures were also dense: Within a square centimeter, the researchers were able to synthesize a forest of more than 100 billion aligned boron nitride nanotubes, that measured about a millimeter in height — large enough to be visible by eye. By nanotube engineering standards, these dimensions are considered to be “bulk” in scale.

      “We are now able to make these nanoscale fibers at bulk scale, which has never been shown before,” Acauan says.

      To demonstrate the flexibility of their technique, the team synthesized larger carbon-based structures, including a weave of carbon fibers, a mat of “fuzzy” carbon nanotubes, and sheets of randomly oriented carbon nanotubes known as “buckypaper.” They coated each carbon-based sample with boron and nitrogen precursors, then went through their process to burn away the underlying carbon. In each demonstration, they were left with a boron-nitride replica of the original black carbon scaffold.

      They also were able to “knock down” the forests of BNNTs, producing horizontally aligned fiber films that are a preferred configuration for incorporating into composite materials.

      “We are now working toward fibers to reinforce ceramic matrix composites, for hypersonic and space applications where there are very high temperatures, and for windows for devices that need to be optically transparent,” Wardle says. “You could make transparent materials that are reinforced with these very strong nanotubes.”

      This research was supported, in part, by Airbus, ANSYS, Boeing, Embraer, Lockheed Martin, Saab AB, and Teijin Carbon America through MIT’s Nano-Engineered Composite aerospace STructures (NECST) Consortium. More

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      in Security

      Two first-year students named Rise Global Winners for 2022

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      In 2019, former Google CEO Eric Schmidt and his wife, Wendy, launched a $1 billion philanthropic commitment to identify global talent. Part of that effort is the Rise initiative, which selects 100 young scholars, ages 15-17, from around the world who show unusual promise and a drive to serve others. This year’s cohort of 100 Rise Global Winners includes two MIT first-year students, Jacqueline Prawira and Safiya Sankari.

      Rise intentionally targets younger-aged students and focuses on identifying what the program terms “hidden brilliance” in any form, anywhere in the world, whether it be in a high school or a refugee camp. Another defining aspect of the program is that Rise winners receive sustained support — not just in secondary school, but throughout their lives.

      “We believe that the answers to the world’s toughest problems lie in the imagination of the world’s brightest minds,” says Eric Braverman, CEO of Schmidt Futures, which manages Rise along with the Rhodes Trust. “Rise is an integral part of our mission to create the best, largest, and most enduring pipeline of exceptional talent globally and match it to opportunities to serve others for life.”

      The Rise program creates this enduring pipeline by providing a lifetime of benefits, including funding, programming, and mentoring opportunities. These resources can be tailored to each person as they evolve throughout their career. In addition to a four-year college scholarship, winners receive mentoring and career services; networking opportunities with other Rise recipients and partner organizations; technical equipment such as laptops or tablets; courses on topics like leadership and human-centered design; and opportunities to apply for graduate scholarships and for funding throughout their careers to support their innovative ideas, such as grants or seed money to start a social enterprise.

      Prawira and Sankari’s winning service projects focus on global sustainability and global medical access, respectively. Prawira invented a way to use upcycled fish-scale waste to absorb heavy metals in wastewater. She first started experimenting with fish-scale waste in middle school to try to find a bio-based alternative to plastic. More recently, she discovered that the calcium salts and collagen in fish scales can absorb up to 82 percent of heavy metals from water, and 91 percent if an electric current is passed through the water. Her work has global implications for treating contaminated water at wastewater plants and in developing countries.

      Prawiri published her research in 2021 and has won awards from the U.S. Environmental Protection Agency and several other organizations. She’s planning to major in Course 3 (materials science and engineering), perhaps with an environmentally related minor. “I believe that sustainability and solving environmental problems requires a multifaced approach,” she says. “Creating greener materials for use in our daily lives will have a major impact in solving current environmental issues.”

      For Sankari’s service project, she developed an algorithm to analyze data from electronic nano-sensor devices, or e-noses, which can detect certain diseases from a patient’s breath. The devices are calibrated to detect volatile organic compound biosignatures that are indicative of diseases like diabetes and cancer. “E-nose disease detection is much faster and cheaper than traditional methods of diagnosis, making medical care more accessible to many,” she explains. The Python-based algorithm she created can translate raw data from e-noses into a result that the user can read.

      Sankari is a lifetime member of the American Junior Academy of Science and has been a finalist in several prestigious science competitions. She is considering a major in Course 6-7 (computer science and molecular biology) at MIT and hopes to continue to explore the intersection between nanotechnology and medicine.

      While the 2022 Rise recipients share a desire to tackle some of the world’s most intractable problems, their ideas and interests, as reflected by their service projects, are broad, innovative, and diverse. A winner from Belarus used bioinformatics to predict the molecular effect of a potential Alzheimer’s drug. A Romanian student created a magazine that aims to promote acceptance of transgender bodies. A Vietnamese teen created a prototype of a toothbrush that uses a nano chip to detect cancerous cells in saliva. And a recipient from the United States designed modular, tiny homes for the unhoused that are affordable and sustainable, as an alternative to homeless shelters.

      This year’s winners were selected from over 13,000 applicants from 47 countries, from Azerbaijan and Burkina Faso to Lebanon and Paraguay. The selection process includes group interviews, peer and expert review of each applicant’s service project, and formal talent assessments. More

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      in Environment

      MADMEC winner identifies sustainable greenhouse-cooling materials

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      The winners of this year’s MADMEC competition identified a class of materials that could offer a more efficient way to keep greenhouses cool.

      After Covid-19 put the materials science competition on pause for two years, on Tuesday SmartClime, a team made up of three MIT graduate students, took home the first place, $10,000 prize.

      The team showed that a type of material that changes color in response to an electric voltage could reduce energy usage and save money if coated onto the panes of glass in greenhouses.

      “This project came out of our love of gardening,” said SmartClime team member and PhD candidate Isabella Caruso in the winning presentation. “Greenhouses let you grow things year-round, even in New England, but even greenhouse pros need to use heating furnaces in the winter and ventilation in the summer. All of that can be very labor- and energy-intensive.”

      Current options to keep greenhouses cool include traditional air conditioning units, venting and fans, and simple cloth. To develop a better solution, the team looked through scientific papers to find materials with the right climate control properties.

      Two classes of materials that looked promising were thermochromic coatings, which change color based on temperature, and electrochromic solutions, which change color based on electric voltage.

      Creating both the thermochromic and electrochromic solutions required the team to assemble nanoparticles and spin-coat them onto glass substrates. In lab tests, the electrochromic material performed well, turning a deep bluish hue to reduce the heat coming into the greenhouse while also letting in enough light for plants. Specifically, the electrochromic cell kept its test box about 1 to 3 degrees Celsius cooler than the test box coated in regular glass.

      The team estimated that greenhouse owners could make back the added costs of the electrochromic paneling through savings on other climate-control measures. Additional benefits of using the material include reducing heat-related crop losses, increasing crop yields, and reducing water requirements.

      Hosted by MIT’s Department of Materials Science and Engineering (DMSE), the competition was the culmination of team projects that began last spring and included a series of design challenges throughout the summer. Each team received guidance, access to equipment and labs, and up to $1,000 in funding to build and test their prototypes.

      “It’s great to be back and to have everyone here in person,” Mike Tarkanian, a senior lecturer in DMSE and coordinator of MADMEC, said at the event. “I’ve enjoyed getting back to normal, doing the design challenges over the summer and celebrating with everyone here today.”

      The second-place prize was split between YarnZ, which identified a nanofiber yarn that is more sustainable than traditional textile fibers, and WasteAway, which has developed a waste bin monitoring device that can identify the types of items thrown into trash and recycling bins and flag misplaced items.

      YarnZ (which stands for Yarns Are Really NanofiberZ), developed a nanofiber yarn that is more degradable than traditional microfiber yarns without sacrificing on performance.

      A large chunk of the waste and emissions in the clothing industry come from polyester, a slow-degrading polymer that requires an energy-intensive melt spinning process before it’s spun into the fibers of our clothes.

      “The biggest thing I want to impress upon you today is that the textile industry is a major greenhouse gas-producing entity and also produces a huge amount of waste,” YarnZ member and PhD candidate Natalie Mamrol said in the presentation.

      To replace polyester, the team developed a continuous process in which a type of nanofiber film collects in a water bath before being twisted into yarn. In subsequent tests, the nanofiber-based yarn degraded more quicky than traditional microfibers and showed comparable durability. YarnZ believes this early data should encourage others to explore nanofibers as a viable replacement in the clothing industry and to invest in scaling the approach for industrial settings.

      WasteAway’s system includes a camera that sits on top of trash bins and uses artificial intelligence to recognize items that people throw away.

      Of the 300 million tons of waste generated in the U.S. each year, more than half ends up in landfills. A lot of that waste could have been composted or recycled but was misplaced during disposal.

      “When someone throws something into the bin, our sensor detects the motion and captures an image,” explains WasteAway’s Melissa Stok, an undergraduate at MIT. “Those images are then processed by our machine-learning algorithm to find contamination.”

      Each device costs less than $30, and the team says that cost could go down as parts are bought at larger scales. The insights gleaned from the device could help waste management officials identify contaminated trash piles as well as inform education efforts by revealing common mistakes people make.

      Overall, Tarkanian believes the competition was a success not only because of the final results, but because of the experience the students got throughout the MADMEC program, which included several smaller, hands-on competitions involving laser cutters, 3-D printers, soldering irons, and other equipment many students said they had never used before.

      “They end up getting into the lab through these design challenges, which have them compete in various engineering tasks,” Tarkanian says. “It helps them get comfortable designing and prototyping, and they often end up using those tools in their research later.” More

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      in Energy

      New process could enable more efficient plastics recycling

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      The accumulation of plastic waste in the oceans, soil, and even in our bodies is one of the major pollution issues of modern times, with over 5 billion tons disposed of so far. Despite major efforts to recycle plastic products, actually making use of that motley mix of materials has remained a challenging issue.

      A key problem is that plastics come in so many different varieties, and chemical processes for breaking them down into a form that can be reused in some way tend to be very specific to each type of plastic. Sorting the hodgepodge of waste material, from soda bottles to detergent jugs to plastic toys, is impractical at large scale. Today, much of the plastic material gathered through recycling programs ends up in landfills anyway. Surely there’s a better way.

      According to new research from MIT and elsewhere, it appears there may indeed be a much better way. A chemical process using a catalyst based on cobalt has been found to be very effective at breaking down a variety of plastics, such as polyethylene (PET) and polypropylene (PP), the two most widely produced forms of plastic, into a single product, propane. Propane can then be used as a fuel for stoves, heaters, and vehicles, or as a feedstock for the production of a wide variety of products — including new plastics, thus potentially providing at least a partial closed-loop recycling system.

      The finding is described today in the open access journal  JACS Au, in a paper by MIT professor of chemical engineering Yuriy Román-Leshkov, postdoc Guido Zichitella, and seven others at MIT, the SLAC National Accelerator Laboratory, and the National Renewable Energy Laboratory.

      Recycling plastics has been a thorny problem, Román-Leshkov explains, because the long-chain molecules in plastics are held together by carbon bonds, which are “very stable and difficult to break apart.” Existing techniques for breaking these bonds tend to produce a random mix of different molecules, which would then require complex refining methods to separate out into usable specific compounds. “The problem is,” he says, “there’s no way to control where in the carbon chain you break the molecule.”

      But to the surprise of the researchers, a catalyst made of a microporous material called a zeolite that contains cobalt nanoparticles can selectively break down various plastic polymer molecules and turn more than 80 percent of them into propane.

      Although zeolites are riddled with tiny pores less than a nanometer wide (corresponding to the width of the polymer chains), a logical assumption had been that there would be little interaction at all between the zeolite and the polymers. Surprisingly, however, the opposite turned out to be the case: Not only do the polymer chains enter the pores, but the synergistic work between cobalt and the acid sites in the zeolite can break the chain at the same point. That cleavage site turned out to correspond to chopping off exactly one propane molecule without generating unwanted methane, leaving the rest of the longer hydrocarbons ready to undergo the process, again and again.

      “Once you have this one compound, propane, you lessen the burden on downstream separations,” Román-Leshkov says. “That’s the essence of why we think this is quite important. We’re not only breaking the bonds, but we’re generating mainly a single product” that can be used for many different products and processes.

      The materials needed for the process, zeolites and cobalt, “are both quite cheap” and widely available, he says, although today most cobalt comes from troubled areas in the Democratic Republic of Congo. Some new production is being developed in Canada, Cuba, and other places. The other material needed for the process is hydrogen, which today is mostly produced from fossil fuels but can easily be made other ways, including electrolysis of water using carbon-free electricity such as solar or wind power.

      The researchers tested their system on a real example of mixed recycled plastic, producing promising results. But more testing will be needed on a greater variety of mixed waste streams to determine how much fouling takes place from various contaminants in the material — such as inks, glues, and labels attached to the plastic containers, or other nonplastic materials that get mixed in with the waste — and how that affects the long-term stability of the process.

      Together with collaborators at NREL, the MIT team is also continuing to study the economics of the system, and analyzing how it can fit into today’s systems for handling plastic and mixed waste streams. “We don’t have all the answers yet,” Román-Leshkov says, but preliminary analysis looks promising.

      The research team included Amani Ebrahim and Simone Bare at the SLAC National Accelerator Laboratory; Jie Zhu, Anna Brenner, Griffin Drake and Julie Rorrer at MIT; and Greg Beckham at the National Renewable Energy Laboratory. The work was supported by the U.S. Department of Energy (DoE), the Swiss National Science Foundation, and the DoE’s Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office (AMO), and Bioenergy Technologies Office (BETO), as part of the the Bio-Optimized Technologies to keep Thermoplastics out of Landfills and the Environment (BOTTLE) Consortium. More

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      in Energy

      Cracking the carbon removal challenge

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      By most measures, MIT chemical engineering spinoff Verdox has been enjoying an exceptional year. The carbon capture and removal startup, launched in 2019, announced $80 million in funding in February from a group of investors that included Bill Gates’ Breakthrough Energy Ventures. Then, in April — after recognition as one of the year’s top energy pioneers by Bloomberg New Energy Finance — the company and partner Carbfix won a $1 million XPRIZE Carbon Removal milestone award. This was the first round in the Musk Foundation’s four-year, $100 million-competition, the largest prize offered in history.

      “While our core technology has been validated by the significant improvement of performance metrics, this external recognition further verifies our vision,” says Sahag Voskian SM ’15, PhD ’19, co-founder and chief technology officer at Verdox. “It shows that the path we’ve chosen is the right one.”

      The search for viable carbon capture technologies has intensified in recent years, as scientific models show with increasing certainty that any hope of avoiding catastrophic climate change means limiting CO2 concentrations below 450 parts per million by 2100. Alternative energies will only get humankind so far, and a vast removal of CO2 will be an important tool in the race to remove the gas from the atmosphere.

      Voskian began developing the company’s cost-effective and scalable technology for carbon capture in the lab of T. Alan Hatton, the Ralph Landau Professor of Chemical Engineering at MIT. “It feels exciting to see ideas move from the lab to potential commercial production,” says Hatton, a co-founder of the company and scientific advisor, adding that Verdox has speedily overcome the initial technical hiccups encountered by many early phase companies. “This recognition enhances the credibility of what we’re doing, and really validates our approach.”

      At the heart of this approach is technology Voskian describes as “elegant and efficient.” Most attempts to grab carbon from an exhaust flow or from air itself require a great deal of energy. Voskian and Hatton came up with a design whose electrochemistry makes carbon capture appear nearly effortless. Their invention is a kind of battery: conductive electrodes coated with a compound called polyanthraquinone, which has a natural chemical attraction to carbon dioxide under certain conditions, and no affinity for CO2 when these conditions are relaxed. When activated by a low-level electrical current, the battery charges, reacting with passing molecules of CO2 and pulling them onto its surface. Once the battery becomes saturated, the CO2 can be released with a flip of voltage as a pure gas stream.

      “We showed that our technology works in a wide range of CO2 concentrations, from the 20 percent or higher found in cement and steel industry exhaust streams, down to the very diffuse 0.04 percent in air itself,” says Hatton. Climate change science suggests that removing CO2 directly from air “is an important component of the whole mitigation strategy,” he adds.

      “This was an academic breakthrough,” says Brian Baynes PhD ’04, CEO and co-founder of Verdox. Baynes, a chemical engineering alumnus and a former associate of Hatton’s, has many startups to his name, and a history as a venture capitalist and mentor to young entrepreneurs. When he first encountered Hatton and Voskian’s research in 2018, he was “impressed that their technology showed it could reduce energy consumption for certain kinds of carbon capture by 70 percent compared to other technologies,” he says. “I was encouraged and impressed by this low-energy footprint, and recommended that they start a company.”

      Neither Hatton nor Voskian had commercialized a product before, so they asked Baynes to help them get going. “I normally decline these requests, because the costs are generally greater than the upside,” Baynes says. “But this innovation had the potential to move the needle on climate change, and I saw it as a rare opportunity.”

      The Verdox team has no illusions about the challenge ahead. “The scale of the problem is enormous,” says Voskian. “Our technology must be in a position to capture mega- and gigatons of CO2 from air and emission sources.” Indeed, the International Panel on Climate Change estimates the world must remove 10 gigatons of CO2 per year by 2050 in order to keep global temperature rise under 2 degrees Celsius.

      To scale up successfully and at a pace that could meet the world’s climate challenge, Verdox must become “a business that works in a technoeconomic sense,” as Baynes puts it. This means, for instance, ensuring its carbon capture system offers clear and competitive cost benefits when deployed. Not a problem, says Voskian: “Our technology, because it uses electric energy, can be easily integrated into the grid, working with solar and wind on a plug-and-play basis.” The Verdox team believes their carbon footprint will beat that of competitors by orders of magnitude.

      The company is pushing past a series of technical obstacles as it ramps up: enabling the carbon capture battery to run hundreds of thousands of cycles before its performance wanes, and enhancing the polyanthraquinone chemistry so that the device is even more selective for CO2.

      After hurtling past critical milestones, Verdox is now working with its first announced commercial client: Norwegian aluminum company Hydro, which aims to eliminate CO2 from the exhaust of its smelters as it transitions to zero-carbon production.

      Verdox is also developing systems that can efficiently pull CO2 out of ambient air. “We’re designing units that would look like rows and rows of big fans that bring the air into boxes containing our batteries,” he says. Such approaches might prove especially useful in locations such as airfields, where there are higher-than-normal concentrations of CO2 emissions present.

      All this captured carbon needs to go somewhere. With XPRIZE partner Carbfix, which has a decade-old, proven method for mineralizing captured CO2 and depositing it in deep underground caverns, Verdox will have a final resting place for CO2 that cannot immediately be reused for industrial applications such as new fuels or construction materials.

      With its clients and partners, the team appears well-positioned for the next round of the carbon removal XPRIZE competition, which will award up to $50 million to the group that best demonstrates a working solution at a scale of at least 1,000 tons removed per year, and can present a viable blueprint for scaling to gigatons of removal per year.

      Can Verdox meaningfully reduce the planet’s growing CO2 burden? Voskian is sure of it. “Going at our current momentum, and seeing the world embrace carbon capture, this is the right path forward,” he says. “With our partners, deploying manufacturing facilities on a global scale, we will make a dent in the problem in our lifetime.” More

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      in Energy

      SMART Innovation Center awarded five-year NRF grant for new deep tech ventures

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      The Singapore-MIT Alliance for Research and Technology (SMART), MIT’s research enterprise in Singapore has announced a five-year grant awarded to the SMART Innovation Center (SMART IC) by the National Research Foundation Singapore (NRF) as part of its Research, Innovation and Enterprise 2025 Plan. The SMART IC plays a key role in accelerating innovation and entrepreneurship in Singapore and will channel the grant toward refining and commercializing developments in the field of deep technologies through financial support and training.

      Singapore has recently expanded its innovation ecosystem to hone deep technologies to solve complex problems in areas of pivotal importance. While there has been increased support for deep tech here, with investments in deep tech startups surging from $324 million in 2020 to $861 million in 2021, startups of this nature tend to take a longer time to scale, get acquired, or get publicly listed due to increased time, labor, and capital needed. By providing researchers with financial and strategic support from the early stages of their research and development, the SMART IC hopes to accelerate this process and help bring new and disruptive technologies to the market.

      “SMART’s Innovation Center prides itself as being one of the key drivers of research and innovation, by identifying and nurturing emerging technologies and accelerating them towards commercialization,” says Howard Califano, director of SMART IC. “With the support of the NRF, we look forward to another five years of further growing the ecosystem by ensuring an environment where research — and research funds — are properly directed to what the market and society need. This is how we will be able to solve problems faster and more efficiently, and ensure that value is generated from scientific research.”

      Set up in 2009 by MIT and funded by the NRF, the SMART IC furthers SMART’s goals by nurturing promising and innovative technologies that faculty and research teams in Singapore are working on. Some emerging technologies include, but are not limited to, biotechnology, biomedical devices, information technology, new materials, nanotechnology, and energy innovations.

      Having trained over 300 postdocs since its inception, the SMART IC has supported the launch of 55 companies that have created over 3,300 jobs. Some of these companies were spearheaded by SMART’s interdisciplinary research groups, including biotech companies Theonys and Thrixen, autonomous vehicle software company nuTonomy, and integrated circuit company New Silicon. During the RIE 2020 period, 66 Ignition Grants and 69 Innovation Grants were awarded to SMART’s researchers, as well as faculty at other Singapore universities and research institutes.

      The following four programs are open to researchers from education and research facilities, as well as institutes of higher learning, in Singapore:

      Innovation Grant 2.0: The enhanced SMART Innovation Center’s flagship program, the Innovation Grant 2.0, is a gated three-phase program focused on enabling scientist-entrepreneurs to launch a successful venture, with training and intense monitoring across all phases. This grant program can provide up to $800,000 Singaporean dollars and is open to all areas of deep technology (engineering, artificial intelligence, biomedical, new materials, etc). The first grant call for the Innovation Grant 2.0 is open through Oct. 15. Researchers, scientists, and engineers at Singapore’s public institutions of higher learning, research centers, public hospitals, and medical research centers — especially those working on disruptive technologies with commercial potential — are invited to apply for the Innovation Grant 2.0.

      I2START Grant: In collaboration with SMART, the National Health Innovation Center Singapore, and Enterprise Singapore, this novel integrated program will develop master classes on venture building, with a focus on medical devices, diagnostics, and medical technologies. The grant amount is up to S$1,350,000. Applications are accepted throughout the year.

      STDR Stream 2: The Singapore Therapeutics Development Review (STDR) program is jointly operated by SMART, the Agency for Science, Technology and Research (A*STAR), and the Experimental Drug Development Center. The grant is available in two phases, a pre-pilot phase of S$100,000 and a Pilot phase of S$830,000, with a potential combined total of up to S$930,000. The next STDR Pre-Pilot grant call will open on Sept. 15.

      Central Gap Fund: The SMART IC is an Innovation and Enterprise Office under the NRF’s Central Gap Fund. This program helps projects that have already received an Innovation 2.0, STDR Stream 2, or I2START Grant but require additional funding to bridge to seed or Series A funding, with possible funding of up to S$5 million. Applications are accepted throughout the year.

      The SMART IC will also continue developing robust entrepreneurship mentorship programs and regular industry events to encourage closer collaboration among faculty innovators and the business community.

      “SMART, through the Innovation Center, is honored to be able to help researchers take these revolutionary technologies to the marketplace, where they can contribute to the economy and society. The projects we fund are commercialized in Singapore, ensuring that the local economy is the first to benefit,” says Eugene Fitzgerald, chief executive officer and director of SMART, and professor of materials science and engineering at MIT.

      SMART was established by MIT and the NRF in 2007 and serves as an intellectual and innovation hub for cutting-edge research of interest to both parties. SMART is the first entity in the Campus for Research Excellence and Technological Enterprise. SMART currently comprises an Innovation Center and five Interdisciplinary Research Groups: Antimicrobial Resistance, Critical Analytics for Manufacturing Personalized-Medicine, Disruptive and Sustainable Technologies for Agricultural Precision, Future Urban Mobility, and Low Energy Electronic Systems.

      The SMART IC was set up by MIT and the NRF in 2009. It identifies and nurtures a broad range of emerging technologies including but not limited to biotechnology, biomedical devices, information technology, new materials, nanotechnology, and energy innovations, and accelerates them toward commercialization. The SMART IC runs a rigorous grant system that identifies and funds promising projects to help them de-risk their technologies, conduct proof-of-concept experiments, and determine go-to-market strategies. It also prides itself on robust entrepreneurship boot camps and mentorship, and frequent industry events to encourage closer collaboration among faculty innovators and the business community. SMART’s Innovation grant program is the only scheme that is open to all institutes of higher learning and research institutes across Singapore. More