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Tag: Materials Science

  • Semiconductor quantum dots create dream material

    Semiconductor quantum dots create dream material

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    Newswise — Researchers from the RIKEN Center for Emergent Matter Science and collaborators have succeeded in creating a “superlattice” of semiconductor quantum dots that can behave like a metal, potentially imparting exciting new properties to this popular class of materials.

    Semiconducting colloidal quantum dots have garnered tremendous research interest due to their special optical properties, which arise from the quantum confinement effect. They are used in solar cells, where they can improve the efficiency of energy conversion, biological imaging, where they can be used as fluorescent probes, electronic displays, and even quantum computing, where their ability to trap and manipulate individual electrons can be exploited.

    However, getting semiconductor quantum dots to efficiently conduct electricity has been a major challenge, impeding their full use. This is primarily due to their lack of orientational order in assemblies. According to Satria Zulkarnaen Bisri, lead researcher on the project, who carried out the research at RIKEN and is now at the Tokyo University of Agriculture and Technology, “making them metallic would enable, for example, quantum dot displays that are brighter yet use less energy than current devices.”

    Now, the group has published a study in Nature Communications that could make a major contribution to reaching that goal. The group, led by Bisri and Yoshihiro Iwasa of RIKEN CEMS, has created a superlattice of lead sulfide semiconducting colloidal quantum dots that displays the electrical conducting properties of a metal.

    The key to achieving this was to get the individual quantum dots in the lattice to attach to one another directly, “epitaxially,” without ligands, and to do this with their facets oriented in a precise way.

    The researchers tested the conductivity of the material they created, and as they increased the carrier density using a electric-double-layer transistor, they found that at a certain point it became one million times more conductive than what is currently available from quantum dot displays. Importantly, the quantum confinement of the individual quantum dots was still maintained, meaning that they don’t lose their functionality despite the high conductivity.

    “Semiconductor quantum dots have always shown promise for their optical properties, but their electronic mobility has been a challenge,” says Iwasa. “Our research has demonstrated that precise orientation control of the quantum dots in the assembly can lead to high electronic mobility and metallic behavior. This breakthrough could open up new avenues for using semiconductor quantum dots in emerging technologies.”

    According to Bisri, “We plan to carry out further studies with this class of materials, and believe it could lead to vast improvements in the capabilities of quantum dot superlattices. In addition to improving current devices, it could lead to new applications such as true all-QD direct electroluminescence devices, electrically driven lasers, thermoelectric devices, and highly sensitive detectors and sensors, which previously were beyond the scope of quantum dot materials.”

    In addition to RIKEN, the team included researchers from Tokyo Institute of Technology, the University of Tokyo, SPring-8, and the Tokyo University of Agriculture and Technology.

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    RIKEN

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  • Development of self-healing lens material to prevent traffic accidents in self-driving cars

    Development of self-healing lens material to prevent traffic accidents in self-driving cars

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    Newswise — Safety issues of self-driving cars have emerged due to frequent self-driving traffic accidents. A self-healing lens material that can prevent car accidents that occur due to signal distortion by restoring scratches on the sensor surface of the self-driving car has been developed.

    The Korea Research Institute of Chemical Technology (KRICT, President Lee, Young Kuk) research team led by Dr. Kim Jin Chul, Park Young Il, and Jeong Ji-Eun* and Prof. Kim Hak-Rin and Prof. Cheong In Woo in Kyungpook National University (KNU) developed a material that heals scratches on the sensor of an autonomous vehicle.
    * Technology from「Can scratches on car surfaces disappear when exposed to sunlight? : A new self-healing coating material」, published in 2022, has been further developed to enable not only structural recovery but also functional recovery such as recovery of an optical signal.

    When this self-healing optical material is used in the sensor of an autonomous vehicle, it is expected that the life expectancy of the product can be increased and future technology that can prevent malfunctions due to surface damage can be secured.

    A lens is a tool that collects or disperses light and is used in many everyday optical devices such as cameras, cell phones, and glasses. However, if the lens surface is damaged by a scratch, the image or optical signal received by the optical device can be severely distorted.

    Recently, traffic accidents caused by recognition errors and malfunctions of vision systems* such as LiDAR sensors and image sensors of self-driving cars have repeatedly occurred. As a result, confidence in the safety of self-driving cars is rather low**.
    * LIDAR sensors and image sensors that acts as the ‘eyes’ of an autonomous vehicle
    ** The results of a survey by the American Automobile Association showed that the number of respondents who were afraid of using self-driving cars increased by 13% from 55% in 2022 to 68% in 2023.

    The KRICT-KNU joint research team developed a transparent lens material that can remove scratches on the sensor surface within 60 seconds when focused sunlight is irradiated using a simple tool such as a magnifying glass.

    Because self-healing is favorable when molecular movement within the polymer is free, flexible materials are generally advantageous in securing excellent self-healing performance. However, lenses or protecting coating materials are made of hard materials, and thus it is very difficult to impart a self-healing function. To solve this problem, the research team combined a thiourethane structure, which is already being used as a lens material, and a transparent photothermal dye* to design a ‘dynamic chemical bond’ in which the polymers repeat disassembly and recombination under irradiation of sunlight.
    * A dye that converts light energy into heat energy

    In particular, the developed transparent organic photothermal dye can selectively absorb light of a specific near-infrared wavelength (850-1050 nm) without interfering with the visible light region (350-850 nm) used for image sensors and the near-infrared region (~1550 nm) used for LiDAR sensors.

    When sunlight is absorbed by photothermal dyes, the surface temperature of the developed lens material rises as the light energy is converted into thermal energy. Subsequently, the increased surface temperature makes it possible to self-heal a surface scratch by repeating the dissociation and recombination of chemical bonds in the polythiourethane structure.

    The developed lens material shows perfect self-healing even when scratches cross each other, and provides excellent resilience, maintaining 100% of the self-healing efficiency even if the process of scratching and healing at the same location is repeated more than five times.

    Dr. Lee Young Kuk, president of KRICT, said, “This technology is a platform technology that synthesizes self-healing lens materials using both an inexpensive high-refractive polymer material and a photothermal dye. It is expected to be widely used in various applications such as autonomous vehicle sensors as well as glasses and cameras.”

     

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     KRICT was established as a government-funded research institute in 1976. It has played a leading role in the development of the national chemical industry as it developed technologies for chemical and related fields of convergence, transferred chemical technologies to industries, produced professionals in the chemical field, and provided tremendous support for a variety of chemical infrastructures. Now we promise to reach new heights in chemistry and chemical engineering and continue our role in facilitating increased use of the knowledge from research. For more information, please visit KRICT’s website at https://www.krict.re.kr/eng/

    This study was supported by the New Career Researcher Program of the National Research Foundation of Korea and Korea Research Institute of Chemical Technology (KRICT). The research was published in the Feb 2023 issue of ‘ACS Applied Materials and Interfaces‘(IF: 10.383), an international scientific and technological journal.

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    National Research Council of Science and Technology

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  • Researchers create high-temp, extreme environment sensors

    Researchers create high-temp, extreme environment sensors

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    Newswise — Extreme environments in several critical industries – aerospace, energy, transportation and defense – require sensors to measure and monitor numerous factors under harsh conditions to ensure human safety and integrity of mechanical systems.

    In the petrochemical industry, for example, pipeline pressures must be monitored at climates ranging from hot desert heat to near arctic cold. Various nuclear reactors operate at a range of 300-1000 degrees Celsius, while deep geothermal wells hold temperatures up to 600 degrees Celsius.

    Now a team of University of Houston researchers has developed a new sensor that was proven to work in temperatures as high as 900 degrees Celsius or 1,650 degrees Fahrenheit, which is the temperature mafic volcanic lava, the hottest type of lava on Earth, erupts.

    “Highly sensitive, reliable and durable sensors that can tolerate such extreme environments are necessary for the efficiency, maintenance and integrity of these applications,” said Jae-Hyun Ryou, associate professor of mechanical engineering at UH and corresponding author of a study published in the journal Advanced Functional Materials.

    The article, which was featured on the cover of the journal, is titled “Piezoelectric Sensors Operating at Very High Temperatures and in Extreme Environments Made of Flexible Ultrawide-Bandgap Single-Crystalline AlN Thin Films.”

    Making It Work

    The UH research team previously developed III-N piezoelectric pressure sensor using single-crystalline Gallium Nitride, or GaN thin films for harsh-environment applications. However, the sensitivity of the sensor decreases at temperatures higher than 350 degrees Celsius, which is higher than those of conventional transducers made of lead zirconate titanate (PZT), but only marginally.

    The team believed the decrease in sensitivity was due to the bandgap – the minimum energy required to excite an electron and supply electrical conductivity – not being wide enough. To test the hypothesis, they developed a sensor with aluminum nitride or AlN.

    “The hypothesis was proven by the sensor operating at about 1000 degrees Celsius, which is the highest operation temperature among the piezoelectric sensors,” said Nam-In Kim, first author of the article and a post-doctoral student working with the Ryou group.

    While both AlN and GaN have unique and excellent properties that are suitable for use in sensors for extreme environments, the researchers were excited to find that AlN offered a wider bandgap and an even higher temperature range. However, the team had to deal with technical challenges involving the synthesis and fabrication of the high-quality, flexible thin film AlN.

    “I have always been interested in making devices using different materials, and I love to characterize various materials. Working in the Ryou group, especially on piezoelectric devices and III-N materials, I was able to use the knowledge I learned in my studies,” said Kim, who earned his Ph.D. in materials science and engineering from UH in 2022. His award-winning dissertation was on flexible piezoelectric sensors for personal health care and extreme environments.

    “It was very interesting to see the process leading to the actual results and we solved the technical challenges during the development and demonstration of the sensor,” he added.

    What’s Next?

    Now that the researchers have successfully demonstrated the potential of the high-temperature piezoelectric sensors with AlN, they will test it further in real-world harsh conditions.

    “Our plan is to use the sensor in several harsh scenarios. For example, in nuclear plants for neutron exposure and hydrogen storage to test under high pressure,” Ryou said. “AlN sensors can operate in neutron-exposed atmospheres and at very high-pressure ranges thanks to its stable material properties.”

    The flexibility of the sensor offers additional advantages that will make it useful for future applications in the form of wearable sensors in personal health care monitoring products and for use in precise-sensing soft robotics.

    The researchers look forward to their sensor being commercially viable at some point in the future. “It’s hard to put a specific date on when that might be, but I think it’s our job as engineers to make it happen as soon as possible,” Kim said.

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    University of Houston

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  • Engineering: Diapers to Houses

    Engineering: Diapers to Houses

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    Newswise — Up to eight percent of the sand in concrete and mortar used to make a single-story house could be replaced with shredded used disposable diapers without significantly diminishing their strength, according to a study published in Scientific Reports. The authors suggest that disposable diaper waste could be used as a construction material for low-cost housing in low- and middle-income countries.

    Disposable diapers are usually manufactured from wood pulp, cotton, viscose rayon, and plastics such as polyester, polyethylene, and polypropylene. The majority are disposed of in landfill or by incineration.

    Siswanti Zuraida and colleagues prepared concrete and mortar samples by combining washed, dried, and shredded disposable diaper waste with cement, sand, gravel, and water. These samples were then cured for 28 days. The authors tested six samples containing different proportions of diaper waste to measure how much pressure they could withstand without breaking. They then calculated the maximum proportion of sand that could be replaced with disposable diapers in a range of building materials that would be needed to construct a house with a floorplan area of 36 square metres that complies with Indonesian building standards.

    The authors found that disposable diaper waste could replace up to ten percent of the sand needed for concrete used to form columns and beams in a three-story house. This proportion increased to 27 percent of sand needed for concrete columns and beams in a single-story house. Up to 40 percent of the sand needed for mortar in partition walls can be replaced with disposable diapers, compared to nine percent of the sand in mortar for floors and garden paving. Together, up to eight percent of the sand in all of the concrete and mortar building materials required to build a single-story house with a floorplan of 36 square metres can be replaced with disposable diaper waste — equivalent to 1.7 cubic metres of waste.

    The authors note that wider implementation of their findings would require the involvement of stakeholders in government and waste treatment in developing processes for the large-scale collection, sanitising, and shredding of diaper waste. Additionally, building regulations would need to be modified to allow the use of diaper waste as a construction material.

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    Article details

    Application of non-degradable waste as building material for low-cost housing

    DOI: 10.1038/s41598-023-32981-y

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    Scientific Reports

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  • Ultralow temperature terahertz microscope capabilities enable better quantum technology

    Ultralow temperature terahertz microscope capabilities enable better quantum technology

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    Newswise — A team of scientists from the Department of Energy’s Ames National Laboratory have developed a way to collect terahertz imaging data on materials under extreme magnetic and cryogenic conditions. They accomplished their work with a new scanning probe microscope. This microscope was recently developed at Ames Lab. The team used the ultralow temperature terahertz microscope to take measurements on superconductors and topological semimetals. These materials were were exposed to high magnetic fields and temperatures below liquid helium (below 4.2 Kelvins or -452 degrees Fahrenheit).

    According to Jigang Wang, a scientist at Ames Lab, professor of Physics and Astronomy at Iowa State University, and the team leader, the team has been improving their terahertz microscope since it was first completed in 2019. “We have improved the resolution in terms of the space, time and energy,” said Wang. “We have also simultaneously improved operation to very low temperatures and high magnetic fields.”

    To expand their terahertz microscope’s capabilities to operate at extreme cryogenic and magnetic environments, Wang explained that his team developed a custom microscopy insert for a cryostat. A cryostat is a device used to maintain extremely cold temperatures. This insert was designed specifically for use with the cryogenic terahertz microscope.

    The new microscope capabilities allowed the team to examine superconductors and topological semimetals, both which operate at these low temperatures. These materials can also move electricity with almost zero energy loss and are important for furthering quantum computing technology.

    Based on their research so far, Wang said that the microscope could lead to development of new, improved materials for highly coherent quantum devices and a better understanding of superconducting and topological materials.

    This research is further discussed in the paper, “A sub-2 Kelvin Cryogenic Magneto-Terahertz Scattering-type Scanning Near-Field Optical Microscope (cm-THz-sSNOM),” written by R. H. J. Kim, J.-M. Park, S. J. Haeuser, L. Luo, and J. Wang, and published in Review of Scientific Instruments.

     

     

    Ames National Laboratory is a U.S. Department of Energy Office of Science National Laboratory operated by Iowa State University. Ames Laboratory creates innovative materials, technologies, and energy solutions. We use our expertise, unique capabilities, and interdisciplinary collaborations to solve global problems.

    Ames Laboratory is supported by the Office of Science of the U.S. Department of Energy. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, please visit https://energy.gov/science.

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    Ames National Laboratory

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  • Circuit boards from renewable raw materials

    Circuit boards from renewable raw materials

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    BYLINE: Rainer Klose

    Newswise — For many years, Thomas Geiger has been conducting research in the field of cellulose fibrils – fine fibers that can be produced from wood pulp or agricultural waste, for example. Cellulose fibrils hold great potential for sustainable production and the decarbonization of industry: they grow CO2-neutral in nature, burn without residues and are even compostable. They can be used for many purposes, for example as fiber reinforcement in technical rubber products such as pump membranes.

    But can cellulose fibrils perhaps also be used to make circuit boards that reduce the ecological footprint of computers? Printed circuit boards (PCBs) in particular are anything but innocent ecologically: They usually consist of glass fibers soaked in expoxy resin. Such a composite material is not recyclable and can so far only be disposed of properly in special pyrolysis plants.

    Computer mouse with an ivory look

    Geiger had already produced circuit boards from cellulose fibrils and investigated their biodegradation. Mixed with water, the bio-fibrils produce a thick sludge that can be dewatered and compacted in a special press. Together with a colleague, he produced 20 experimental boards, which were subjected to various mechanical tests and finally fitted with electronic components. The test succeeded, and the cellulose board released the soldered-on components after a few weeks in natural soil.

    Geiger had previously been involved in an Innosuisse project together with the OST University of Applied Sciences in Rapperswil, which produced housing parts for computer mice. The housing parts have a silky sheen and are similar in color and feel to workpieces made of ivory. But no manufacturer could be found who wanted to adopt the method. The price competition for small electronics is still too great for this – and conventional plastic injection molding processes have a clear advantage in this respect.

    Circuit boards made of wood wool or cellulose fibers and fibrils

    Recently, the opportunity arose to build on existing findings: Empa sustainability specialist Claudia Som was asked if she would like to collaborate on the EU research project Hypelignum. This is led by the Swedish materials research institute RISE and is looking for new ways of sustainably producing electronics. Claudia Som enlisted the help of her colleague Thomas Geiger.

    The project started in October 2022, and the research consortium, with participants from Austria, Slovenia, Spain, the Netherlands, Sweden and Switzerland, plans to produce and evaluate eco circuit boards made of various materials: In addition to nanofibrillated cellulose (CNF), wood wool and wood pulp are being investigated as a base; wood veneer is also being used as a base for the circuit boards.

    Two Empa labs are collaborating on the project: Firstly, the sustainability specialists led by Claudia Som from the Technology and Society lab. Som will use material databases to calculate the ecological footprint of the eco circuit boards and compare the individual concepts with each other. Thomas Geiger from Empa’s Cellulose & Wood Materials laboratory will manufacture the circuit boards from renewable raw materials. Green electronics has long been a research focus of the lab, which is headed by Gustav Nyström; Nyström’s team has already developed various printed electronic components from biodegradable materials, such as batteries and displays. The requirements for industrially produced computer circuit boards, however, are not trivial: Not only must the boards have high mechanical strength, they must also not swell in humid conditions or form cracks at very low humidity.

    “Cellulose fibers can be a very good alternative to glass fiber composites,” Geiger explains. “We dewater the material in a special press with 150 tons of pressure. Then the cellulose fibrils stick together on their own without any additives. We call this ‘hornification’.” The key here is at what pressure, temperature and for how long the pressing process must take place to produce optimal results.

    Four demonstrators planned

    The EU project Hypelignum has ambitious goals: It aims not only to study printed circuit boards made from renewable and compostable raw materials, but also to develop conductive inks for the electrical connections between individual components. These inks are often made based on silver nanoparticles. The researchers are looking for cheaper and less scarce substitute materials, as well as an ecological production method for these nanoparticles.

    At the end of the project, four demonstrators ought to show what had been achieved: an ecologically exemplary printed circuit board, a large construction element made of wood that will be equipped with sensors and actuators, pieces of furniture that will be equipped with sensors in an automated production line, and finally a demonstrator that will prove the recyclability of all these components.

    Infobox: Displays and batteries made from cellulose

    In 2022, an Empa research group led by Gustav Nyström succeeded in building a biodegradable display based on hydroxypropyl cellulose (HPC). They used HPC as a substrate and added a small amount of carbon nanotubes, making the cellulose electrically conductive. By mixing in cellulose nanofibers (CNF), they brought the ink into a printable form. The display changes color depending on the applied electrical voltage; in addition, it can also serve as a pressure or tension sensor and has the potential to play a role as a biodegradable user interface in future eco-electronics.

    https://www.empa.ch/web/s604/bioelektronik

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    Empa, Swiss Federal Laboratories for Materials Science and Technology

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  • Garnet solid electrolytes can be recycled via thermal healing

    Garnet solid electrolytes can be recycled via thermal healing

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    Newswise — Metallic lithium is considered as the ultimate anode material of next-generation high-performance energy storage system, owing to its ultrahigh theoretical specific capacity (3860 mA h g-1), ultralow electrochemical potential (-3.04 V vs. the standard hydrogen electrode), and low density (0.534 g cm-3). Employing Li metal as high-capacity anode, solid-state lithium-metal batteries (SSLMBs) are becoming one of the most promising candidates for next-generation energy storage devices, due to their high safety and potential high energy density. SSLMBs are expected to be the future for conventional lithium-ion batteries. However, the development of SSLMBs is still limited, due to the severe safety issues caused by the uncontrolled Li dendrite formation and growth. Besides, the strategies focusing on healing or recycling solid electrolytes with Li dendrite penetration are rarely reported.

    Recently, a study is led by the group of Prof. Wei Liu (School of Physical Science and Technology, ShanghaiTech University). In this study, they demonstrate a facile method for healing and recycling garnet electrolytes (Ta doped Li7La3Zr2O12: LLZTO) with Li dendrites through heat treatment. Excitingly, the recycled garnet ceramic pellets have increased ionic conductivity with higher relative density, which is due to the dendrite-derived species (LiOH and Li2CO3) in the grain boundaries are able to promote further densification of garnet electrolyte pellets during thermal healing process as sintering aids (Figure). Compared with pristine garnet electrolyte pellets, the relative density of the recycled garnet pellets is improved from 90.9% to 95.3%, and ionic conductivity is improved from 0.39 to 0.62 mS cm-1. Benefited from the enhanced relative density and ionic conductivity, a higher critical current density (CCD) is achieved, suggesting a better suppression effect on Li dendrite penetration.

     

    See the article:

    Recycling of garnet solid electrolytes with lithium-dendrite penetration by thermal healing

    https://link.springer.com/article/10.1007/s40843-022-2371-9

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    Science China Press

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  • New AI system can create proteins to fit design targets

    New AI system can create proteins to fit design targets

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    Newswise — MIT researchers are using artificial intelligence to design new proteins that go beyond those found in nature.

    They developed machine-learning algorithms that can generate proteins with specific structural features, which could be used to make materials that have certain mechanical properties, like stiffness or elasticity. Such biologically inspired materials could potentially replace materials made from petroleum or ceramics, but with a much smaller carbon footprint.

    The researchers from MIT, the MIT-IBM Watson AI Lab, and Tufts University employed a generative model, which is the same type of machine-learning model architecture used in AI systems like DALL-E 2. But instead of using it to generate realistic images from natural language prompts, like DALL-E 2 does, they adapted the model architecture so it could predict amino acid sequences of proteins that achieve specific structural objectives.

    In a paper to be published in Chem, the researchers demonstrate how these models can generate realistic, yet novel, proteins. The models, which learn biochemical relationships that control how proteins form, can produce new proteins that could enable unique applications, says senior author Markus Buehler, the Jerry McAfee Professor in Engineering and professor of civil and environmental engineering and of mechanical engineering.

    For instance, this tool could be used to develop protein-inspired food coatings, which could keep produce fresh longer while being safe for humans to eat. And the models can generate millions of proteins in a few days, quickly giving scientists a portfolio of new ideas to explore, he adds. 

    “When you think about designing proteins nature has not discovered yet, it is such a huge design space that you can’t just sort it out with a pencil and paper. You have to figure out the language of life, the way amino acids are encoded by DNA and then come together to form protein structures. Before we had deep learning, we really couldn’t do this,” says Buehler, who is also a member of the MIT-IBM Watson AI Lab.

    Joining Buehler on the paper are lead author Bo Ni, a postdoc in Buehler’s Laboratory for Atomistic and Molecular Mechanics; and David Kaplan, the Stern Family Professor of Engineering and professor of bioengineering at Tufts.

    Adapting new tools for the task

    Proteins are formed by chains of amino acids, folded together in 3D patterns. The sequence of amino acids determines the mechanical properties of the protein. While scientists have identified thousands of proteins created through evolution, they estimate that an enormous number of amino acid sequences remain undiscovered.

    To streamline protein discovery, researchers have recently developed deep learning models that can predict the 3D structure of a protein for a set of amino acid sequences. But the inverse problem — predicting a sequence of amino acid structures that meet design targets — has proven even more challenging.

    A new advent in machine learning enabled Buehler and his colleagues to tackle this thorny challenge: attention-based diffusion models.

    Attention-based models can learn very long-range relationships, which is key to developing proteins because one mutation in a long amino acid sequence can make or break the entire design, Buehler says. A diffusion model learns to generate new data through a process that involves adding noise to training data, then learning to recover the data by removing the noise. They are often more effective than other models at generating high-quality, realistic data that can be conditioned to meet a set of target objectives to meet a design demand.

    The researchers used this architecture to build two machine-learning models that can predict a variety of new amino acid sequences which form proteins that meet structural design targets.

    “In the biomedical industry, you might not want a protein that is completely unknown because then you don’t know its properties. But in some applications, you might want a brand-new protein that is similar to one found in nature, but does something different. We can generate a spectrum with these models, which we control by tuning certain knobs,” Buehler says.

    Common folding patterns of amino acids, known as secondary structures, produce different mechanical properties. For instance, proteins with alpha helix structures yield stretchy materials while those with beta sheet structures yield rigid materials. Combining alpha helices and beta sheets can create materials that are stretchy and strong, like silks.

    The researchers developed two models, one that operates on overall structural properties of the protein and one that operates at the amino acid level. Both models work by combining these amino acid structures to generate proteins. For the model that operates on the overall structural properties, a user inputs a desired percentage of different structures (40 percent alpha-helix and 60 percent beta sheet, for instance). Then the model generates sequences that meet those targets. For the second model, the scientist also specifies the order of amino acid structures, which gives much finer-grained control.

    The models are connected to an algorithm that predicts protein folding, which the researchers use to determine the protein’s 3D structure. Then they calculate its resulting properties and check those against the design specifications.

    Realistic yet novel designs

    They tested their models by comparing the new proteins to known proteins that have similar structural properties. Many had some overlap with existing amino acid sequences, about 50 to 60 percent in most cases, but also some entirely new sequences. The level of similarity suggests that many of the generated proteins are synthesizable, Buehler adds.

    To ensure the predicted proteins are reasonable, the researchers tried to trick the models by inputting physically impossible design targets. They were impressed to see that, instead of producing improbable proteins, the models generated the closest synthesizable solution.

    “The learning algorithm can pick up the hidden relationships in nature. This gives us confidence to say that whatever comes out of our model is very likely to be realistic,” Ni says.

    Next, the researchers plan to experimentally validate some of the new protein designs by making them in a lab. They also want to continue augmenting and refining the models so they can develop amino acid sequences that meet more criteria, such as biological functions. 

    “For the applications we are interested in, like sustainability, medicine, food, health, and materials design, we are going to need to go beyond what nature has done. Here is a new design tool that we can use to create potential solutions that might help us solve some of the really pressing societal issues we are facing,” Buehler says.

    This research was supported, in part, by the MIT-IBM Watson AI Lab, the U.S. Department of Agriculture, the U.S. Department of Energy, the Army Research Office, the National Institutes of Health, and the Office of Naval Research.

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    Written by Adam Zewe, MIT News Office

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    Massachusetts Institute of Technology (MIT)

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  • New research advances stable and affordable organic solar cells for renewable electricity

    New research advances stable and affordable organic solar cells for renewable electricity

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    Newswise — Due to the recent improvements in the efficiency with which solar cells made from organic (carbon-based) semiconductors can convert sunlight into electricity, improving the long-term stability of these photovoltaic devices is becoming an increasingly important topic.  Real-world applications of the technology demand that the efficiency of the photovoltaic device be maintained for many years. To address this key problem, researchers have studied the degradation mechanisms for the two components used in the light-absorbing layer of organic solar cells: the ‘electron donor’ and ‘electron acceptor’ materials. These two components are needed to split the bound electron-hole pair formed after the absorption of a photon into the free electrons and holes that constitute electrical current.

    In this new study reported in Joule, an international team of researchers led by the Cavendish Laboratory, University of Cambridge, have for the first time considered the degradation pathways of both the electron donor and electron acceptor materials. The detailed investigation of the electron donor material sets the current research work apart from the previous studies and provides important new insights for the field. Specifically, the identification of an ultrafast deactivation process unique to the electron donor material has not been observed before and provides a new angle to consider material degradation in organic solar cells.

    To understand how these materials degraded, the Cavendish researchers worked as part of an international team with scientists in the UK, Belgium, and Italy. Together, they combined photovoltaic device stability studies, where the operational solar cell is subject to intense light that closely matches sunlight, with ultrafast laser spectroscopy performed in Cambridge. Through this laser technique, they have been able to identify a new degradation mechanism in the electron donor material involving twisting in the polymer chain. As a result, when the twisted polymer absorbs a photon, it undergoes an extremely rapid deactivation pathway on femtosecond timescales (a millionth billionth of a second). This undesirable process is fast enough to outcompete the generation of free electrons and holes from a photon, which the scientists were able to correlate with the reduced efficiency of the organic solar cell after it had been exposed to simulated sunlight.

    “It was interesting to find that something as seemingly minor as the twisting of a polymer chain could have such a large effect on the solar cell efficiency,” said Dr. Alex Gillett, the lead author of the paper. “In the future, we plan to build on our findings by collaborating with chemistry groups to design new electron donor materials with more rigid polymer backbones. We hope that this will reduce the propensity of the polymer to twist and thus improve the stability of the organic solar cell device.”

    Due to their unique properties, organic solar cells can be used in a wide range of applications for which traditional silicon photovoltaics aren’t suitable. This could include electricity generating windows for greenhouses that transmit the colours of light required for photosynthesis, or even photovoltaics that could be rolled up for easy transportation and mobile electricity generation. Thus, by identifying the degradation mechanism that needs to be solved, the current research directly brings the next generation of photovoltaic materials and applications closer to reality.

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    University of Cambridge

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  • Farm waste turned into air-cleaning substance

    Farm waste turned into air-cleaning substance

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    Newswise — Air pollution and its high concentration in cities is one of the problems facing society today, due to its harmful effects on the environment, but also on human health. One of the causes of this pollution is the increase in nitrogen oxide emissions, mainly due to the use of fossil fuels.

    While the emissions of these gases are being reduced, photocatalysis is proving to be a tool for decontaminating air in cities: materials called semiconductors are created which, when coming into contact with the pollutant, under the effect of ultraviolet light, cause it to degrade, thus reducing its concentration in the air.

    Two research groups of the University of Cordoba, belonging to the Chemical Institute for Energy and the Environment (IQUEMA),and the Department of Inorganic Chemistry and Chemical Engineering,have been working to produce these materials. The team,formed by the BioPrEn and Inorganic Chemistry groups, has obtained biodegradable materials to fix nanoparticles with photocatalytic activity (in this case, titanium dioxide), augmentingthe power and, therefore,the decontaminating effect.

    The advances made by this work consist of “first, the creation of a biodegradable medium based on nanocellulose, obtained from agricultural waste; and, second, the development of a surface modification process of these nanoparticles, which results on their greater dispersion and immobilization,and, therefore, enhanced photocatalytic activity”, explains one of the authors of the article, researcher Eduardo Espinosa.

    The progress is twofold: it is possible to create a sustainable material by recovering a form of agricultural waste(thus contributing to the Circular Economy) and the process of fixing photocatalytic nanoparticles to this biodegradable medium is simplified. The benefit is, in fact, exponential, since the result is greater air decontamination due to the porosity and the three-dimensional nature of the material, which means that more photocatalytic particles are exposed to ultraviolet light compared to an opaque material or one in which only one surface is exposed to light.

    What is it like? Where is it used?

    Those who see this material will recognize a light, solid foam, but with very little density, similar to insulation coverings used in construction,or the popular corn “puffs.” To effect decontamination “it can be used as a porous filter through which the gas stream passes, always exposed to ultraviolet light, and the gas comes out decontaminated,” says Espinosa. Thus, gases released by industry, for example, would come out almost clean of nitrogen oxides.

    A further step in this research would be to modify the photocatalytic particle so that it is more sensitive to light from the visible spectrum, without having to resort to ultraviolet sources. In this way the photocatalytic power would be activated by sunlight alone, and this type of technology could be applied to textiles and other types of materials,thereby reducing the concentration of gases only through exposure to the sun.

    References:

    Carrasco, Sergio & Espinosa Víctor, Eduardo & González, Zoilo & Cruz-Yusta, Manuel & Sánchez, Luis & Rodríguez, Alejandro (2023). Simple Route to Prepare Composite Nanocellulose Aerogels: A Case of Photocatalytic De-NO x Materials Application. ACS Sustainable Chemistry &Engineering. https://doi.org/10.1021/acssuschemeng.2c06170

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  • New SLAC-Stanford Battery Center targets roadblocks to a sustainable energy transition

    New SLAC-Stanford Battery Center targets roadblocks to a sustainable energy transition

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    Newswise — Menlo Park, Calif. – The Department of Energy’s SLAC National Accelerator Laboratory and Stanford University today announced the launch of a new joint battery center at SLAC. It will bring together the resources and expertise of the national lab, the university and Silicon Valley to accelerate the deployment of batteries and other energy storage solutions as part of the energy transition that’s essential for addressing climate change.

    A key part of this transition will be to decarbonize the world’s transportation systems and electric grids ­– to power them without fossil fuels. To do so, society will need to develop the capacity to store several hundred terawatt-hours of sustainably generated energy. Only about 1% of that capacity is in place today.

    Filling the enormous gap between what we have and what we need is one of the biggest challenges in energy research and development. It will require that experts in chemistry, materials science, engineering and a host of other fields join forces to make batteries safer, more efficient and less costly and manufacture them more sustainably from earth-abundant materials, all on a global scale. 

    The SLAC-Stanford Battery Center will address that challenge. It will serve as the nexus for battery research at the lab and the university, bringing together large numbers of faculty, staff scientists, students and postdoctoral researchers from SLAC and Stanford for research, education and workforce training. 

     “We’re excited to launch this center and to work with our partners on tackling one of today’s most pressing global issues,” said interim SLAC Director Stephen Streiffer. “The center will leverage the combined strengths of Stanford and SLAC, including experts and industry partners from a wide variety of disciplines, and provide access to the lab’s world-class scientific facilities. All of these are important to move novel energy storage technologies out of the lab and into widespread use.”

    Expert research with unique tools

    Research and development at the center will span a vast range of systems – from understanding chemical reactions that store energy in electrodes to designing battery materials at the nanoscale, making and testing devices, improving manufacturing processes and finding ways to scale up those processes so they can become part of everyday life. 

    “It’s not enough to make a game-changing battery material in small amounts,” said Jagjit Nanda, a SLAC distinguished scientist, Stanford adjunct professor and executive director of the new center, whose background includes decades of battery research at DOE’s Oak Ridge National Laboratory. “We have to understand the manufacturing science needed to make it in larger quantities on a massive scale without compromising on performance.”

    Longstanding collaborations between SLAC and Stanford researchers have already produced many important insights into how batteries work and how to make them smaller, lighter, safer and more powerful. These studies have used machine learning to quickly identify the most promising battery materials from hundreds made in the lab, and measured the properties of those materials and the nanoscale details of battery operation at the lab’s synchrotron X-ray facility. SLAC’s X-ray free-electron laser is available, as well, for fundamental studies of energy-related materials and processes. 

    SLAC and Stanford also pioneered the use of cryogenic electron microscopy (cryo-EM), a technique developed to image biology in atomic detail, to get the first clear look at finger-like growths that can degrade lithium-ion batteries and set them on fire. This technique has also been used to probe squishy layers that build up on electrodes and must be carefully managed, in research performed at the Stanford Institute for Materials and Energy Sciences (SIMES).

    Nanda said the center will also focus on making energy storage more sustainable, for instance by choosing materials that are abundant, easy to recycle and can be extracted in a way that’s less costly and produces fewer emissions.

    A unique collaboration in the heart of Silicon Valley 

    Battery Center Director Will Chueh, an associate professor at Stanford and faculty scientist at SLAC, emphasized that the center is located in the middle of Silicon Valley’s entrepreneurial culture, two miles from the Stanford campus and a short walk away from large, world-class scientific facilities that only a national lab can provide. This generates advantages that would be impossible for any single partner to achieve, including outstanding educational and training opportunities for Stanford students and postdocs that will play an outsized role in shaping the next generation of energy researchers. 

    “There’s no other place in the world,” Chueh said, “where all of this comes together.”

    A pilot project for the center began in 2020 with two battery laboratories in SLAC’s Arrillaga Science Center where Stanford students and postdoctoral researchers have been synthesizing battery materials and evaluating devices. 

    The center is operated by SLAC’s Applied Energy Division and Stanford’s Precourt Energy Institute. Major funding for battery research at SLAC comes from the DOE Office of Science and Office of Energy Efficiency and Renewable Energy. SLAC’s Stanford Synchrotron Radiation Lightsource (SSRL) and Linac Coherent Light Source (LCLS) X-ray free-electron laser are DOE Office of Science user facilities.

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  • Next-Generation Aramid Fiber with Electrical Conductivity

    Next-Generation Aramid Fiber with Electrical Conductivity

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    Newswise — Aramid fiber is known as “super fiber” or “golden silk” because even though its weight is equivalent to only 20% of the weight of steel, it is more than five times as strong and does not burn, even at 500 °C. Aramid fiber is an essential material used in various applications such as body armor, fire-resistant clothing, fiber optic cable reinforcement, high-performance tires, and aerospace materials. The late Dr. Han-Sik Yun began researching aramid fiber at the Korea Institute of Science and Technology (KIST) in 1979 and secured independent source technology in 1984.

    Dr. Dae-Yoon Kim and his research team at the Functional Composite Materials Research Center within the KIST Jeonbuk Institute of Advanced Composite Materials announced that they have applied carbon nanotubes to aramid fibers to develop a new kind of composite fiber. In addition to being lightweight, strong, and fire-resistant, the fiber also has electrical conductivity, which is a first for conventional aramid fibers. The newly developed fiber is black in color due to the presence of carbon nanotubes.

    Inspired by the characteristics of a silkworm cocoon, the KIST research team succeeded in combining aramid, which has extremely low dispersibility, with carbon nanotubes. By utilizing the liquid crystal phase, silkworms produce high-strength fiber using high-concentration protein. Possessing both liquid-like fluidity and crystal-like order, the liquid crystal minimizes the coagulation of aramid and carbon nanotubes as well as improves the alignment. Utilizing these characteristics, the research team created a new type of composite fiber with high level of specific strength similar to that of existing commercial aramid fibers, as well as a specific electrical conductivity level of approximately 90% of that of copper wires.

    Despite these electrical characteristics, this next-generation aramid fiber does not use any metals, resulting in flexibility, non-corrosiveness, and a lightweight profile (approximately 30% of the weight of copper wires). It is expected to be used as a next-generation wire in various applications, such as smart military, medical robots, eco-friendly mobility, and aerospace technologies. Dr. Dae-Yoon Kim added, “This technology will have a significant impact on the super fiber market.”

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    KIST was established in 1966 as the first government-funded research institute in Korea. KIST now strives to solve national and social challenges and secure growth engines through leading and innovative research. For more information, please visit KIST’s website at https://eng.kist.re.kr/

    This research was supported by KIST’s K-Lab program and NRF’s Excellent Young Research Program and was published in Advanced Fiber Materials (IF: 12.924, JCR 1.923%), a prestigious international academic journal in the field of fiber.

     

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  • Solid electrolyte for all-solid-state batteries without high-temperature heat treatment

    Solid electrolyte for all-solid-state batteries without high-temperature heat treatment

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    Newswise — The all-solid-state battery is a secondary battery with a solid electrolyte between the anode and cathode. It is considered a representative of next-generation battery technology due to its high energy density and significantly lower risk of fire and explosion than conventional lithium-ion batteries. In recent years, materials research in the field of all-solid-state batteries has been focused on strategies to maximize material crystallinity to achieve ionic conductivity similar to that of liquid electrolytes (ionic conductivity of 10 mS/cm or more). However, this approach requires a high-temperature crystallization step (above 500 °C) of up to several days after material mixing or reaction. It resulted in high process costs and battery interface contact issues due to reduced mechanical deformability.

    Dr. Hyoungchul Kim’s research team at the Energy Materials Research Center, Korea Institute of Science and Technology (KIST, President Seok Jin Yoon), announced that they have successfully synthesized a solid electrolyte with superionic conductivity and high elastic deformability in a one-pot process at room temperature and normal pressure. This research has garnered attention because it can maximize the productivity of all-solid-state battery materials and solve the inherent interface problem by improving elastic deformation.

    Dr. Kim’s research team focused on the crystallographic features of the argyrodite sulfides to synthesize a highly deformable and ionically conductive solid-state electrolyte material under normal temperature and pressure conditions. Theoretically, ionic conductivity can be maximized by maximizing the halogen substitution rate at the 4a and 4c sites in the argyrodite crystal, but the material has never been practically synthesized due to its thermodynamic instability. In addition, typical crystalline argyrodite superconductors require high-temperature heat treatment above 500 °C. Therefore, the halogen substitution rate cannot be maximized, and the elastic modulus decreases with increasing crystallinity, leading to rapid degradation of cell performance. In contrast, without high-temperature heat treatment, a low elastic modulus similar to that of glass can be obtained; however, the ionic conductivity remains around 3 mS/cm, limiting its applicability as a solid-state electrolyte.

    The research team came up with a new strategy to obtain a thermodynamically unstable structure (i.e., fully halogenated argyrodite) that takes advantage of both crystalline and glassy properties. They developed a composition control method to lower the crystallization temperature of argyrodite as well as a new two-step mechanochemical milling process suitable for the lower crystallization temperature. This facilitated the synthesis of a fully halogen-substituted (~90.67% substitution) argyrodite with a superionic conductivity of ~13.23 mS/cm without a long high-temperature annealing. The synthesized material also possesses an elastic modulus of about 12.51 GPa, which is one of the lowest reported values for superionic-conductive solid electrolytes, and this is also advantageous for improving the interfacial performance of all-solid-state batteries. Moreover, the new one-pot process at room temperature and normal pressure can be completed in less than 15 h, which is the highest productivity for any solid electrolyte with superionic conductivity. This is a unique achievement, with material productivity that is approximately 2-6 times higher than those of conventional processes for synthesizing superconductive solid electrolytes.

    “We have succeeded in developing a new solid electrolyte material with high deformability and ionic conductivity through a new process at normal temperature and pressure,” said Dr. Kim of KIST, who led the research. He also expressed his expectation, saying, “The new material will serve as a trigger for the commercialization of all-solid-state batteries suitable for electric vehicles and energy storage systems (ESS) because it has maximized material productivity by eliminating the high-temperature heat treatment and simultaneously possesses high deformability and superionic conductivity suitable for solving the problem of the electrode interface of all-solid-state batteries.”

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    KIST was established in 1966 as the first government-funded research institute in Korea. KIST now strives to solve national and social challenges and secure growth engines through leading and innovative research. For more information, please visit KIST’s website at https://eng.kist.re.kr/

    This research was supported by the KIST Institutional Program and the Mid-Career Researcher Support Project funded by the Ministry of Science and ICT (Minister Jong-Ho Lee), and by the Ministry of Trade, Industry and Energy (Minister Chang-Yang Lee) for the development of lithium-based next-generation secondary battery performance enhancement and manufacturing technology. The results were published in Advanced Functional Materials (IF: 19.924, top 4.658% in JCR) recently.

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  • Advanced technologies for longer-lasting electric vehicles

    Advanced technologies for longer-lasting electric vehicles

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    Newswise — Owing to the worldwide trend of utilizing electric vehicles, there has been a rise in demand for next-generation secondary batteries with higher capacity and faster charging than the lithium-ion batteries currently in use. Lithium metal batteries have been recognized as promising rechargeable batteries because lithium metal anode exhibits theoretical capacity 10 times higher than commercial graphite anode. During charging-discharging processes, however, lithium dendrites grow on the anode, leading to poor battery performance and short-circuit.

    Dr. Sungho Lee, Head of the Carbon Composite Materials Research Center of the KIST Jeonbuk Institute of Advanced Composition Materials (President Dr. Seok-Jin Yoon, Director General Jin-Sang Kim) and Professor KwangSup Eom, the Gwangju Institute of Science and Technology (GIST, Acting President Rae-Gil Park), have developed a technology to improve the durability using carbon fiber paper as the anode material for lithium metal batteries.

    The KIST-GIST joint research team replaced the lithium metal-coated copper thin film with a thin carbon fiber paper containing lithium metal. The developed carbon fiber paper possessed hierarchical structure on the carbon monofilament composed of amorphous carbon and inorganic nanoparticles, resulting in enhancing the lithium affinity and preventing the growth of lithium dendrite. Although copper thin film anode short-circuits after approximately 100 cycles, the developed carbon fiber paper anode exhibits excellent cycling stability for 300 cycles. Furthermore, lithium metal battery using developed carbon fiber paper shows a high energy density of 428 Wh/kg, which is approximately 1.8 times higher than that using copper thin film (240 Wh/kg). From a process point of view, another advantage is to simplify the electrode manufacturing process because the molten lithium is quickly infused into the carbon fiber paper.

    Regarding the significance of this research, Dr. Sung-Ho Lee, Head of the Center at KIST, who led the research, said, “Considering the five times lower density and lower cost of carbon fiber compared to copper, our proposed anode material is an important achievement that can accelerate the commercialization of durable and lightweight lithium metal batteries.”

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    KIST was established in 1966 as the first government-funded research institute in Korea. KIST now strives to solve national and social challenges and secure growth engines through leading and innovative research. For more information, please visit KIST’s website at https://eng.kist.re.kr/

    This research was carried out as a KIST Institutional Program and a nanomaterial technology development project under the support of the Ministry of Science and ICT (Minister Lee Jong-ho). The results were published in the January issue of the international journal Advanced Energy Materials (IF=29.698, JCR top 2.464%).

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  • Securing new metal 3D printing technology that drives the renaissance of the manufacturing industry!

    Securing new metal 3D printing technology that drives the renaissance of the manufacturing industry!

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    Newswise — A research team led by Dr. Sang-woo Song, Dr. Chan-kyu Kim, Dr. Kang-myung Seo at the Department of Joining Technology of the Korea Institute of Materials Science(KIMS), a government-funded research institute under the Ministry of Science and ICT, has developed a foundational technology for controlling the volume of molten metal in the process of 3D printing metal using welding techniques. They achieved this through collaborative research with a research team led by Professor Young-tae Cho and Professor Seok Kim of the Department of Mechanical engineering at Changwon National University, and a research team led by Dr. Dae-won Cho of Busan Machinery Research Center at the Korea Institute of Machinery & Materials. As a result, they have successfully developed a metal 3D printing pen technology that can continuously print metal in a three-dimensional space with freedom.

    The metal 3D printing pen technology developed by the research team has the advantage of being able to freely and continuously print metal with freedom in the direction of the welding torch’s movement in 3D space. Compared to conventional metal 3D printing using lasers, the equipment construction cost is low, and additive manufacturing can be performed quickly using commercially available welding materials, making it more economical.

    Metal additive manufacturing using welding techniques has limitations in realizing complex structures because it is a limited process of building one layer at a time. This is because subsequent layers are laminated after complete solidification preventing the molten metal from flowing down. Due to this, there is a disadvantage in that a cooling time is required and the conditions that can be laminated are limited to specific examples. To solve this problem, the research team performed computer analysis to calculate and precisely control the surface tension of the molten metal and the solidified volume according to convection/conduction. Additionally, they developed a technology that can perform metal additive manufacturing in all conditions, including horizontal, vertical, inclined, and overhead positions. By continuously laminating the metal in the liquid phase before it fully solidifies, the manufacturing time is shortened, there is no boundary between layers, and it forms a dense microstructure with excellent mechanical properties.

    ※ In the case of ductility, 24.5% improvement compared to the existing WAAM (Wire Arc Additive Manufacturing) process, based on Inconel 625 (WAAM: welding and additive manufacturing (AM) of wire-type materials using an arc heat source)

    As of 2021, the size of the 3D printer market at home and abroad is KRW 82.1 billion and USD 2.1 billion, respectively, with annual average growth rates of 10.5% and 20%. This research achievement is expected to give vitality to the manufacturing industry by preoccupying technological superiority in the field of metal additive manufacturing and manufacturing high-value-added machines and parts using it.

    “We added 3D free-form additive manufacturing to the continuous additive manufacturing process, which was considered impossible in the existing metal additive manufacturing process,” said Sang-woo Song, principal researcher at KIMS, who is in charge of the research. He continued, “Like the existing 3D printing technology using polymers, it is possible to easily manufacture complex structures using existing metal welding materials, suggesting a new paradigm for the manufacturing industry.”

    This research result was carried out as a project of ‘Development of Multi-metallic Layer Materials for Multi-purpose Micro Modular Reactor’ by the Korea Institute of Materials Science with the support of the Ministry of Science and ICT. In addition, the research results were selected as a cover paper in the February issue of Advanced Science (IF=17.521), a world-renowned academic journal. Currently, the research team is continuing follow-up research for additive manufacturing of high-value-added machinery and parts in the nuclear power plant and defense industries.

     

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    About Korea Institute of Materials Science(KIMS)

    KIMS is a non-profit government-funded research institute under the Ministry of Science and ICT of the Republic of Korea. As the only institute specializing in comprehensive materials technologies in Korea, KIMS has contributed to Korean industry by carrying out a wide range of activities related to materials science including R&D, inspection, testing&evaluation, and technology support.

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  • New ways to measure curls and kinks could make it easier to care for natural hair

    New ways to measure curls and kinks could make it easier to care for natural hair

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    Newswise — INDIANAPOLIS, March 26, 2023 — Black women and others with curly or kinky hair encounter a vast and confusing array of haircare options. Advice on the best products to use for a certain type of hair is often contradictory, and the results can be highly variable. Now, scientists are bringing order to this chaos by identifying properties such as the number of curls or coils in a given length of hair that could eventually help users pick the perfect product and achieve consistent results.

    The researchers will present their findings today at the spring meeting of the American Chemical Society (ACS). ACS Spring 2023 is a hybrid meeting being held virtually and in-person March 26–30, and features more than 10,000 presentations on a wide range of science topics.

    “As an African American, I was born with very curly, seemingly unmanageable hair, and other ethnicities can possess similar hair properties,” says Michelle Gaines, Ph.D., the project’s principal investigator. Gaines used to rely on chemical relaxers to straighten her tresses but stopped when she became pregnant. She was then confronted with an overwhelming variety of products available to style and care for natural hair. Limited guidance about the best options for her particular hair type, and conflicting advice from friends, YouTube videos and other resources, didn’t help the situation.

    Clearly, Gaines says, there is a major knowledge gap that needs to be closed, so she has set out to fill it. “As a polymer chemist and materials scientist, I thought it would be great to start a project where I could study the nuances of my hair, because I felt like it wasn’t very well understood,” she says.

    Most prior research on properties was done on wavy or straight strands from white or Asian people, according to Gaines, who is at Spelman College, a historically Black college for women. Less is known about what has traditionally been called “African” hair, she says, though researchers at Groote Schuur Hospital and the University of Cape Town in South Africa have published some findings.

    L’Oréal, as well as celebrity hair stylist Andre Walker and others, have developed systems to classify different types of hair. Walker’s system ranges from straight to kinky, a category including tight coils and zig-zag strands with angular bends. Although some people believe all of these classification methods convey a preference for a smoother and straighter appearance — a bias with historic links to the preferential treatment of enslaved people who had straighter hair and lighter skin — they’re intended to help users choose the most suitable haircare products. Gaines felt these systems worked well for straight and wavy hair but lacked the nuance to distinguish the many varieties of curly and kinky hair.

    Gaines wanted to see if she could identify differences in properties other than curl shape and tightness, and then use those differences to develop a more precise and quantitative classification system. Undergraduates at Spelman eagerly lined up to help. Gaines and her student, Imani Page, are collaborating with Alfred Crosby, Ph.D., and Gregory Grason, Ph.D., at the University of Massachusetts Amherst; their expertise includes material property characterization and modeling of complex materials and soft matter.

    The team measured the mechanical properties of wavy, curly and kinky hairs with a texture analyzer and a dynamic mechanical analyzer. These instruments measure force, stress and other parameters as a strand is first uncurled and then stretched until it breaks.

    Among other findings, the team recently reported results for the “stretch ratio,” a new parameter they developed to quantify and compare the force required to uncurl a strand until it’s straight. That ratio was found to be negligible for straight hair (since it can’t be uncurled), about 0.8 for wavy, 1.1 for kinky and 1.4 for curly. This measurement could therefore be used as an indicator of the initial curliness of a sample, providing a quantifiable way to distinguish between these types.

    The team also measured geometric properties, such as the diameter, cross section and 3D shape of strands, using optical microscopy, scanning electron microscopy (SEM) and a camera. In addition, the researchers developed new parameters, including the number of complete waves, curls or coils — known as contours — that they measured on 3-cm lengths of hair. They found that wavy hair has less than one full contour in that length, curly has about two, and kinky/coily has approximately three or more. The results suggest that people will be able to classify their own hair by counting contours, Gaines says.

    In the latest work, Gaines has begun examining the layer that protects the surface of each hair fiber. Known as the cuticle, it consists of flat cells that overlap each other, like roof shingles. Cuticles have a natural tendency to open and close reversibly when exposed to water, shampoo and conditioner. However, excessive acid and moisture retention can cause permanent damage to the cuticles, causing them to remain irreversibly lifted, thus exposing the inner cortex of the hair fiber. Irreversibly lifted cuticles, and cuticles that easily open and close, make the strand more porous, which causes more moisture absorption. Gaines’ preliminary findings show the cuticle layers are larger and spaced further apart in wavy hair than in curly and coily hair. Also, the cuticle edges are smoother in wavy hair. These findings could help the researchers explain why curly and coily locks dry out faster than wavy and straight tresses. Ultimately, Gaines hopes, the team’s findings will identify the best parameters for developers to design and for consumers to select the most suitable products for each of the wondrously varied categories of hair.

    The researchers acknowledge support from the University of Massachusetts Amherst.

    A recorded media briefing on this topic will be posted Monday, March 27, by 10 a.m. Eastern time at www.acs.org/acsspring2023briefings. Reporters can request access to media briefings during the embargo period by contacting [email protected].

    For health and safety information for ACS Spring 2023, please visit the FAQ webpage.

    The American Chemical Society (ACS) is a nonprofit organization chartered by the U.S. Congress. ACS’ mission is to advance the broader chemistry enterprise and its practitioners for the benefit of Earth and all its people. The Society is a global leader in promoting excellence in science education and providing access to chemistry-related information and research through its multiple research solutions, peer-reviewed journals, scientific conferences, eBooks and weekly news periodical Chemical & Engineering News. ACS journals are among the most cited, most trusted and most read within the scientific literature; however, ACS itself does not conduct chemical research. As a leader in scientific information solutions, its CAS division partners with global innovators to accelerate breakthroughs by curating, connecting and analyzing the world’s scientific knowledge. ACS’ main offices are in Washington, D.C., and Columbus, Ohio.

    To automatically receive news releases from the American Chemical Society, contact [email protected].

    Note to journalists: Please report that this research was presented at a meeting of the American Chemical Society.

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    Title
    Reimagining hair science: A new approach to classify curly hair phenotypes via new quantitative geometrical & structural mechanical parameters 

    Abstract
    Hair science holds a great impact on society in the cosmetics industry and in biomedicine. Over the last few decades, there has been a significant societal paradigm shift for people with curly hair to accept the natural morphological structure of their curls and style their hair according to the innate, distinct, and unique material properties that their curly hair possesses. These societal and cultural shifts have given rise the development of new hair typing systems, beyond the traditional and highly limited ethnicity-based distinction between Caucasian, Mongolian, and African types. L’Oréal developed a hair typing taxonomy based on quantitative geometric features among the four key curl patterns – straight, wavy, curly, and coily, however the system fails to address the complex diversity of curly and coily hair. Andre Walker’s classification system is the existing gold standard for classifying curly hair types, however the system relies upon qualitative measures to classify hair type, which makes the system vague and ambiguous to the full diversity of phenotypic differences. The goal of this research is to use quantitative methods to identify new geometric parameters to better classify curly and coily hair and therefore provide more information on the kinds of personal care products that will resonate best with these curl patterns. The motivation behind employing hair typing is to better categorize hair phenotype and target appropriate personal care products tailored for specific hair phenotypes to maximize the desired appearance and overall hair health. This was accomplished by distinguishing new mechanical and physical properties of several types of human hair samples. Mechanical properties were measured under tensile extension using a texture analyzer (TA) and a dynamic mechanical analyzer (DMA). Both instruments measure force as a function of applied displacement, thus allowing the relationship between stress and applied stretch ratio to be measured as a hair strand uncurls and stretches to the point of fracture. Morphological properties were measured using scanning electron microscopy (SEM), photogrammetry, and optical microscopy. From the resulting data, correlations were made between fiber structure and mechanical performance. This data will be used to draw more conclusions on the contribution that morphology has on hair fiber mechanics and will promote cultural inclusion among researchers possessing curly and coily hair.

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    American Chemical Society (ACS)

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  • Colorful films could help buildings, cars keep their cool

    Colorful films could help buildings, cars keep their cool

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    Newswise — INDIANAPOLIS, March 26, 2023 — The cold blast of an air conditioner can be a welcome relief as temperatures soar, but “A/C” units require large amounts of energy and can leak potent greenhouse gases. Today, scientists report an eco-friendly alternative — a plant-based film that gets cooler when exposed to sunlight and comes in a variety of textures and bright, iridescent colors. The material could someday keep buildings, cars and other structures cool without requiring external power.

    The researchers will present their results at the spring meeting of the American Chemical Society (ACS). ACS Spring 2023 is a hybrid meeting being held virtually and in-person March 26–30 and features more than 10,000 presentations on a wide range of science topics.

    “To make materials that remain cooler than the air around them during the day, you need something that reflects a lot of solar light and doesn’t absorb it, which would transform energy from the light into heat,” says Silvia Vignolini, Ph.D., the project’s principal investigator. “There are only a few materials that have this property, and adding color pigments would typically undo their cooling effects,” Vignolini adds.

    Passive daytime radiative cooling (PDRC) is the ability of a surface to emit its own heat into space without it being absorbed by the air or atmosphere. The result is a surface that, without using any electrical power, can become several degrees colder than the air around it. When used on buildings or other structures, materials that promote this effect can help limit the use of air conditioning and other power-intensive cooling methods.

    Some paints and films currently in development can achieve PDRC, but most of them are white or have a mirrored finish, says Qingchen Shen, Ph.D., who is presenting the work at the meeting. Both Vignolini and Shen are at Cambridge University (U.K.). But a building owner who wanted to use a blue-colored PDRC paint would be out of luck — colored pigments, by definition, absorb specific wavelengths of sunlight and only reflect the colors we see, causing undesirable warming effects in the process.

    But there’s a way to achieve color without the use of pigments. Soap bubbles, for example, show a prism of different colors on their surfaces. These colors result from the way light interacts with differing thicknesses of the bubble’s film, a phenomenon called structural color. Part of Vignolini’s research focuses on identifying the causes behind different types of structural colors in nature. In one case, her group found that cellulose nanocrystals (CNCs), which are derived from the cellulose found in plants, could be made into iridescent, colorful films without any added pigment.

    As it turns out, cellulose is also one of the few naturally occurring materials that can promote PDRC. Vignolini learned this after hearing a talk from the first researchers to have created a cooling film material. “I thought wow, this is really amazing, and I never really thought cellulose could do this.”

    In recent work, Shen and Vignolini layered colorful CNC materials with a white-colored material made from ethyl cellulose, producing a colorful bi-layered PDRC film. They made films with vibrant blue, green and red colors that, when placed under sunlight, were an average of nearly 40 F cooler than the surrounding air. A square meter of the film generated over 120 Watts of cooling power, rivaling many types of residential air conditioners. The most challenging aspect of this research, Shen says, was finding a way to make the two layers stick together — on their own, the CNC films were brittle, and the ethyl cellulose layer had to be plasma-treated to get good adhesion. The result, however, was films that were robust and could be prepared several meters at a time in a standard manufacturing line.

    Since creating these first films, the researchers have been improving their aesthetic appearance. Using a method modified from approaches previously explored by the group, they’re making cellulose-based cooling films that are glittery and colorful. They’ve also adjusted the ethyl cellulose film to have different textures, like the differences between types of wood finishes used in architecture and interior design, says Shen. These changes would give people more options when incorporating PDRC effects in their homes, businesses, cars and other structures.

    The researchers now plan to find ways they can make their films even more functional. According to Shen, CNC materials can be used as sensors to detect environmental pollutants or weather changes, which could be useful if combined with the cooling power of their CNC-ethyl cellulose films. For example, a cobalt-colored PDRC on a building façade in a car-dense, urban area could someday keep the building cool and incorporate detectors that would alert officials to higher levels of smog-causing molecules in the air.

    The researchers acknowledge support and funding from Purdue University, the American Society of Mechanical Engineers, the European Research Council, the Engineering and Physical Sciences Research Council, the Biotechnology and Biological Sciences Research Council, the European Union and Shanghai Jiao Tong University.

    A recorded media briefing on this topic will be posted Monday, March 27, by 10 a.m. Eastern time at www.acs.org/acsspring2023briefings. Reporters can request access to media briefings during the embargo period by contacting [email protected].

    For health and safety information for ACS Spring 2023, please visit the FAQ webpage.

    The American Chemical Society (ACS) is a nonprofit organization chartered by the U.S. Congress. ACS’ mission is to advance the broader chemistry enterprise and its practitioners for the benefit of Earth and all its people. The Society is a global leader in promoting excellence in science education and providing access to chemistry-related information and research through its multiple research solutions, peer-reviewed journals, scientific conferences, eBooks and weekly news periodical Chemical & Engineering News. ACS journals are among the most cited, most trusted and most read within the scientific literature; however, ACS itself does not conduct chemical research. As a leader in scientific information solutions, its CAS division partners with global innovators to accelerate breakthroughs by curating, connecting and analyzing the world’s scientific knowledge. ACS’ main offices are in Washington, D.C., and Columbus, Ohio.

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    Title
    Structurally colored radiative cooling cellulosic films 

    Abstract
    Daytime radiative cooling (DRC) materials offer a sustainable approach to thermal management by exploiting net positive heat transfer to deep space. While such materials typically have a white or mirror-like appearance to maximize solar reflection, extending the palette of available colors is required to promote their real-world utilization. However, the incorporation of conventional absorption-based colorants inevitably leads to solar heating, which counteracts any radiative cooling effect. In this work, efficient sub-ambient DRC (Day: −4 °C, Night: −11 °C) from a vibrant, structurally colored film prepared from naturally derived cellulose nanocrystals (CNCs), is instead demonstrated. Arising from the underlying photonic nanostructure, the film selectively reflects visible light resulting in intense, fade-resistant coloration, while maintaining a low solar absorption (~3%).  Additionally, a high emission within the mid-infrared atmospheric window (>90%) allows for significant radiative heat loss. By coating such CNC films onto a highly scattering, porous ethylcellulose (EC) base layer, any sunlight that penetrates the CNC layer is backscattered by the EC layer below, achieving broadband solar reflection and vibrant structural color simultaneously. Finally, scalable manufacturing using a commercially relevant roll-to-roll process validates the potential to produce such colored radiative cooling materials at a large scale from a low-cost and sustainable feedstock.

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    American Chemical Society (ACS)

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  • Tackling counterfeit seeds with “unclonable” labels

    Tackling counterfeit seeds with “unclonable” labels

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    Newswise — Average crop yields in Africa are consistently far below expected, and one significant reason is the prevalence of counterfeit seeds whose germination rates are far lower than those of the genuine ones. The World Bank estimates that as much as half of all seeds sold in some African countries are fake, which could help to account for crop production that is far below potential.

    There have been many attempts to prevent this counterfeiting through tracking labels, but none have proved effective; among other issues, such labels have been vulnerable to hacking because of the deterministic nature of their encoding systems. But now, a team of MIT researchers has come up with a kind of tiny, biodegradable tag that can be applied directly to the seeds themselves, and that provides a unique randomly created code that cannot be duplicated.

    The new system, which uses minuscule dots of silk-based material, each containing a unique combination of different chemical signatures, is described today in the journal Science Advances in a paper by MIT’s dean of engineering Anantha Chandrakasan, professor of civil and environmental engineering Benedetto Marelli, postdoc Hui Sun, and graduate student Saurav Maji.

    The problem of counterfeiting is an enormous one globally, the researchers point out, affecting everything from drugs to luxury goods, and many different systems have been developed to try to combat this. But there has been less attention to the problem in the area of agriculture, even though the consequences can be severe. In sub-Saharan Africa, for example, the World Bank estimates that counterfeit seeds are a significant factor in crop yields that average less than one-fifth of the potential for maize, and less than one-third for rice. 

    Marelli explains that a key to the new system is creating a randomly-produced physical object whose exact composition is virtually impossible to duplicate. The labels they create “leverage randomness and uncertainty in the process of application, to generate unique signature features that can be read, and that cannot be replicated,” he says.

    What they’re dealing with, Sun adds, “is the very old job of trying, basically, not to get your stuff stolen. And you can try as much as you can, but eventually somebody is always smart enough to figure out how to do it, so nothing is really unbreakable. But the idea is, it’s almost impossible, if not impossible, to replicate it, or it takes so much effort that it’s not worth it anymore.”

    The idea of an “unclonable” code was originally developed as a way of protecting the authenticity of computer chips, explains Chandrakasan, who is the Vannevar Bush Professor of Electrical Engineering and Computer Science. “In integrated circuits, individual transistors have slightly different properties coined device variations,” he explains, “and you could then use that variability and combine that variability with higher-level circuits to create a unique ID for the device. And once you have that, then you can use that unique ID as a part of a security protocol. Something like transistor variability is hard to replicate from device to device, so that’s what gives it its uniqueness, versus storing a particular fixed ID.” The concept is based on what are known as physically unclonable functions, or PUFs.

    The team decided to try to apply that PUF principle to the problem of fake seeds, and the use of silk proteins was a natural choice because the material is not only harmless to the environment but also classified by the Food and Drug Administration in the “generally recognized as safe” category, so it requires no special approval for use on food products.

    “You could coat it on top of seeds,” Maji says, “and if you synthesize silk in a certain way, it will also have natural random variations. So that’s the idea, that every seed or every bag could have a unique signature.”

    Developing effective secure system solutions have long been one of Chandrakasan’s specialties, while Marelli has spent many years developing systems for applying silk coatings to a variety of fruits, vegetables, and seeds, so their collaboration was a natural for developing such a silk-based coding system towards enhanced security. 

    “The challenge was what type of form factor to give to silk,” Sun says, “so that it can be fabricated very easily.” They developed a simple drop-casting approach that produces tags that are less than one-tenth of an inch in diameter. The second challenge was to develop “a way where we can read the uniqueness, in also a very high throughput and easy way.”

    For the unique silk-based codes, Marelli says, “eventually we found a way to add a color to these microparticles so that they assemble in random structures.” The resulting unique patterns can be read out not only by a spectrograph or a portable microscope, but even by an ordinary cellphone camera with a macro lens. This image can be processed locally to generate the PUF code and then sent to the cloud and compared with a secure database to ensure the authenticity of the product. “It’s random so that people cannot easily replicate it,” says Sun. “People cannot predict it without measuring it.”

    And the number of possible permutations that could result from the way they mix four basic types of colored silk nanoparticles is astronomical. “We were able to show that with a minimal amount of silk, we were able to generate 128 random bits of security,” Maji says. “So this gives rise to 2 to the power 128 possible combinations, which is extremely difficult to crack given the computational capabilities of the state-of-the-art computing systems.”

    Marelli says that “for us, it’s a good test bed in order to think out-of-the-box, and how we can have a path that somehow is more democratic.” In this case, that means “something that you can literally read with your phone, and you can fabricate by simply drop casting a solution, without using any advanced manufacturing technique, without going in a clean room.”

    Some additional work will be needed to make this a practical commercial product, Chandrakasan says. “There will have to be a development for at-scale reading” via smartphones. “So. that’s clearly a future opportunity.” But the principle now shows a clear path to the day when “a farmer could at least, maybe not every seed, but could maybe take some random seeds in a particular batch and verify them,” he says.

    The research was partially supported by the U.S. Office of Naval research and the National Science Foundation, Analog Devices Inc., an EECS Mathworks fellowship, and a Paul M. Cook Career Development Professorship.

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    Massachusetts Institute of Technology (MIT)

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  • KICT Develops World’s First STF-based Stemming Solution for the Construction Blasting Industry

    KICT Develops World’s First STF-based Stemming Solution for the Construction Blasting Industry

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    Newswise — Breaking news in the world of construction and mining; Korea Institute of Civil Engineering and Building Technology (KICT, President Kim Byung-suk) has developed the world’s first shear thickening fluid (STF) based stemming solution. This is the first time that a STF has been developed into a blasting construction material or product for stemming, promising to revolutionize construction blasting with groundbreaking levels of efficiency and safety.

    Blasting is a crucial process in both mining and construction. However, low blasting efficiency has been an issue that has long plagued the blasting industry. Low blasting efficiency is when the target (most commonly rock) is not well broken down compared to the mass of explosives used. Selecting the right stemming material plays an important part in optimizing blasting operations, allowing reduced costs and enhancing the productivity and profitability of excavation and mining.

    Stemming is a process in industrial blasting in which a blasting hole is sealed with stemming materials to prevent the leaking of explosion gases from the blast hole. The use of inadequate stemming materials can lead to over 50% of the explosive energy being lost during a blasting operation. On top of the economic loss incurred by the waste of resources, the excess energy that leaks into the outward is converted to ground vibrations and noise, which may even cause environmental damage.

    This STF-based stemming solution has been named “SMART-STEM” by the team of KICT researchers who developed it. The research team at the KICT Department of Geotechnical Engineering Research (Dr. Moonkyung Chung, Dr. Younghun Ko, Dr. Seunghwan Seo) performed numerous tests over a period of 3 years from 2020 onward. The findings showed that “SMART-STEM” increased resistance to the eruption of explosive gases by 330% compared to the conventional sand-based stemming materials, while rock blasting performance was improved by more than 60%. 

    On-site demonstration of tunnel blasting in urban centers with high population density was also completed through a third-party validation test conducted in August 2022 in a very deep underground urban expressway construction site in Busan, South Korea. The excavation rate per blast increased greatly, with a reduction in total explosive consumption of up to 20%, leading to a reduction of ground blasting vibration in residential area of up to 50%.

    The newly developed “SMART-STEM” offers consistently robust and uniform sealing performance, reducing explosive consumption in blasting sites by simply substituting the existing stemming material with an affordable STF-based material. Moreover, with enhanced tunnel excavation rate per blast and reduced secondary work time, it can help reduce construction costs by up to 17%.

    The lead researcher of the project, Dr. Moonkyung Chung, commented, “I anticipate ‘SMART-STEM’ to be utilized as a mainstay of tunnel construction and other blasting projects in the urban centers of Korea. The construction blasting industry will be able to achieve more efficiency and effectiveness in blasting projects, raising their productivity and profitability by adopting the ‘SMART-STEM’ technology.”

    “SMART-STEM” was developed by a research team (2020∼2022, Team Leader: Dr. Moonkyung Chung) at the Korea Institute of Civil Engineering and Building Technology as a task under one of the institute’s key projects, “Development of new stemming material and blasting method using shear thickening fluid by high shock wave reaction.”

     

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    The Korea Institute of Civil Engineering and Building Technology (KICT) is a government sponsored research institute established to contribute to the development of Korea’s construction industry and national economic growth by developing source and practical technology in the fields of construction and national land management.

    This research was supported by a grant from the project “Development of new stemming material and blasting method using shear thickening fluid by high shock-wave reaction”, funded by the Korea Institute of Civil Engineering and Building Technology (KICT).

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    National Research Council of Science and Technology

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  • Detection of Methanol Using a Soft Photonic Crystal Robot

    Detection of Methanol Using a Soft Photonic Crystal Robot

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    Newswise — Robots are currently employed in industrial sites and fields, including disaster rescue, medicine, security, and national defense. Conventional metal-based robots exert strong operating power due to rigid body construction with joints connected to actuators such as motors. However, they may have difficulty with flexible movements and can cause harm during malfunctions. Recently, ‘soft robots’ made of smooth and flexible materials have emerged, but they may be more difficult to control than metal-based robots.

    Korea Institute of Science and Technology (KIST, President Seok Jin Yoon) announced that the research team composed of Dr. Dae-Yoon Kim of the Functional Composite Materials Research Center, Dr. Seung-Yeol Jeon of the Carbon Composite Materials Research Center, and Prof. Kwang-Un Jeong of the Department of Polymer-Nano Science and Technology at Jeonbuk National University (JBNU, President O Bong Yang) has succeeded in manufacturing a soft robot with a Janus structure, and developing a smart sensor for methanol detection. Excessive exposure to methanol may be fatal to humans and cause headaches, vomiting, dizziness, and visual disturbances. However, as methanol is more than 70% cheaper than ethanol, cases of misuse and abuse are increasing after COVID-19.

    Inspired by the free motions of mollusks such as the octopus, the research team adopted a method of allowing the movements of the soft robot to react spontaneously to the surrounding environment rather than controlling it with precise computing. By patterning two types of flexible polymer films with different expandability, the soft robot was allowed to move naturally in the desired direction according to the surrounding environment. Its motions include bending, folding, and twisting. In addition, a helicoidal nanostructure found in insects, such as butterflies, was introduced into soft robots, resulting in photonic crystal properties that selectively reflect the light of various colors. When the soft robot moves due to changes in the surrounding environment, the user can easily recognize this through color changes.

    The authors developed a sensor that can easily and quickly detect methanol contamination in water by applying the developed soft photonic crystal robot. The methanol detection sensor using the soft photonic crystal robot is economical because it can be reused many times. The robot does not require electricity to operate, so it can easily detect methanol in water in any location. Additionally, the circular polarization properties from the helicoidal nanostructure of the soft robot are difficult to forge and alter, so they are very effective in securing product reliability.

    Dr. Dae-Yoon Kim of KIST said: “This research has significance in implementing soft robots in everyday life. In the future, when multi-stimulus responsive materials capable of promptly and simultaneously responding to various external stimuli are developed, soft robots will be widely commercialized.”

     

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    KIST was established in 1966 as the first government-funded research institute in Korea. KIST now strives to solve national and social challenges and secure growth engines through leading and innovative research. For more information, please visit KIST’s website at https://eng.kist.re.kr/

    This research was conducted with the support of the K-Lab program of KIST and the Young Researcher Program of NRF. The research findings were published in ‘Advanced Functional Materials’ and selected as the frontispiece and hot topic in the field of robotics.

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    National Research Council of Science and Technology

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