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Highly Efficient and Stable Double Layer Solar Cell Developed Solar cells convert light into energy, but they can be inefficient and vulnerable to the environment, degrading with, ironically, too much light or other factors, including moisture and low temperature. An international research team has developed a new type of solar cell that can both withstand environmental hazards and is 26.7% efficient in power conversion. They published their results on March 26 in Science. The researchers, led by Byungha Shin, a professor from the Department of Materials Science and Engineering at KAIST, focused on developing a new class of light-absorbing material, called a wide bandgap perovskite. The material has a highly effective crystal structure that can process the power needs, but it can become problematic when exposed to environmental hazards, such as moisture. Researchers have made some progress increasing the efficiency of solar cells based on perovskite, but the material has greater potential than what was previously achieved. To achieve better performance, Shin and his team built a double layer solar cell, called tandem, in which two or more light absorbers are stacked together to better utilize solar energy. To use perovskite in these tandem devices, the scientists modified the material’s optical property, which allows it to absorb a wider range of solar energy. Without the adjustment, the material is not as useful in achieving high performing tandem solar cells. The modification of the optical property of perovskite, however, comes with a penalty — the material becomes hugely vulnerable to the environment, in particular, to light. To counteract the wide bandgap perovskite’s delicate nature, the researchers engineered combinations of molecules composing a two-dimensional layer in the perovskite, stabilizing the solar cells. “We developed a high-quality wide bandgap perovskite material and, in combination with silicon solar cells, achieved world-class perovskite-silicon tandem cells,” Shin said. The development was only possible due to the engineering method, in which the mixing ratio of the molecules building the two-dimensional layer are carefully controlled. In this case, the perovskite material not only improved efficiency of the resulting solar cell but also gained durability, retaining 80% of its initial power conversion capability even after 1,000 hours of continuous illumination. This is the first time such a high efficiency has been achieved with a wide bandgap perovskite single layer alone, according to Shin. “Such high-efficiency wide bandgap perovskite is an essential technology for achieving ultra-high efficiency of perovskite-silicon tandem (double layer) solar cells,” Shin said. “The results also show the importance of bandgap matching of upper and lower cells in these tandem solar cells.” The researchers, having stabilized the wide bandgap perovskite material, are now focused on developing even more efficient tandem solar cells that are expected to have more than 30% of power conversion efficiency, something that no one has achieved yet, “Our ultimate goal is to develop ultra-high-efficiency tandem solar cells that contribute to the increase of shared solar energy among all energy sources,” Shin said. “We want to contribute to making the planet healthier.” This work was supported by the National Research Foundation of Korea, the Korea Institute of Energy Technology Evaluation and Planning, the Ministry of Trade Industry and Energy of Korea, and the U.S. Department of Energy. Other contributors include Daehan Kim, Jekyung Kim, Passarut Boonmongkolras, Seong Ryul Pae and Minkyu Kim, all of whom affiliated with the Department of Materials Science and Engineering at KAIST. Other authors include Byron W. Larson, Sean P. Dunfield, Chuanxiao Xiao, Jinhui Tong, Fei Zhang, Joseph J. Berry, Kai Zhu and Dong Hoe Kim, all of who are affiliated with the National Renewable Energy Laboratory in Colorado. Dunfield is also affiliated with the Materials Science and Engineering Program at the University of Colorado; Berry is also affiliated with the Department of Physics and the Renewable and Sustainable Energy Institute at the University of Colorado Boulder; and Kim is also affiliated with the Department of Nanotechnology and Advanced Materials Engineering at Sejong University. Hee Joon Jung and Vinayak Dravid of the Department of Materials Science and Engineering at Northwestern University; Ik Jae Park, Su Geun Ji and Jin Young Kim of the Department of Materials Science and Engineering at Seoul National University; and Seok Beom Kang of the Department of Nanotechnology and Advanced Materials Engineering of Sejong University also contributed. Image credit: Professor Byungha Shin, KAIST Image usage restrictions: News organizations may use or redistribute this image, with proper attribution, as part of news coverage of this paper only. Publication: Kim et al. (2020) “Efficient, stable silicon tandem cells enabled by anion-engineered wide band gap perovskites”. Science. Available online at https://doi.org/10.1126/science.aba3433 Profile: Byungha Shin Professor byungha@kaist.ac.kr http://energymatlab.kaist.ac.kr/ Department of Materials Science and Engineering KAIST Profile: Daehan Kim Ph.D. Candidate zxzx4592@kaist.ac.kr http://energymatlab.kaist.ac.kr/ Department of Materials Science and Engineering KAIST (END)
2020.03.27 View 17478
Ultrathin but Fully Packaged High-Resolution Camera - Biologically inspired ultrathin arrayed camera captures super-resolution images. - The unique structures of biological vision systems in nature inspired scientists to design ultracompact imaging systems. A research group led by Professor Ki-Hun Jeong have made an ultracompact camera that captures high-contrast and high-resolution images. Fully packaged with micro-optical elements such as inverted micro-lenses, multilayered pinhole arrays, and gap spacers on the image sensor, the camera boasts a total track length of 740 μm and a field of view of 73°. Inspired by the eye structures of the paper wasp species Xenos peckii, the research team completely suppressed optical noise between micro-lenses while reducing camera thickness. The camera has successfully demonstrated high-contrast clear array images acquired from tiny micro lenses. To further enhance the image quality of the captured image, the team combined the arrayed images into one image through super-resolution imaging. An insect’s compound eye has superior visual characteristics, such as a wide viewing angle, high motion sensitivity, and a large depth of field while maintaining a small volume of visual structure with a small focal length. Among them, the eyes of Xenos peckii and an endoparasite found on paper wasps have hundreds of photoreceptors in a single lens unlike conventional compound eyes. In particular, the eye structures of an adult Xenos peckii exhibit hundreds of photoreceptors on an individual eyelet and offer engineering inspiration for ultrathin cameras or imaging applications because they have higher visual acuity than other compound eyes. For instance, Xenos peckii’s eye-inspired cameras provide a 50 times higher spatial resolution than those based on arthropod eyes. In addition, the effective image resolution of the Xenos peckii’s eye can be further improved using the image overlaps between neighboring eyelets. This unique structure offers higher visual resolution than other insect eyes. The team achieved high-contrast and super-resolution imaging through a novel arrayed design of micro-optical elements comprising multilayered aperture arrays and inverted micro-lens arrays directly stacked over an image sensor. This optical component was integrated with a complementary metal oxide semiconductor image sensor. This is first demonstration of super-resolution imaging which acquires a single integrated image with high contrast and high resolving power reconstructed from high-contrast array images. It is expected that this ultrathin arrayed camera can be applied for further developing mobile devices, advanced surveillance vehicles, and endoscopes. Professor Jeong said, “This research has led to technological advances in imaging technology. We will continue to strive to make significant impacts on multidisciplinary research projects in the fields of microtechnology and nanotechnology, seeking inspiration from natural photonic structures.” This work was featured in Light Science & Applications last month and was supported by the National Research Foundation (NRF) of and the Ministry of Health and Welfare (MOHW) of Korea. Image credit: Professor Ki-Hun Jeong, KAIST Image usage restrictions: News organizations may use or redistribute this image, with proper attribution, as part of news coverage of this paper only. Publication: Kisoo Kim, Kyung-Won Jang, Jae-Kwan Ryu, and Ki-Hun Jeong. (2020) “Biologically inspired ultrathin arrayed camera for high-contrast and high-resolution imaging”. Light Science & Applications. Volume 9. Article 28. Available online at https://doi.org/10.1038/s41377-020-0261-8 Profile: Ki-Hun Jeong Professor kjeong@kaist.ac.kr http://biophotonics.kaist.ac.kr/ Department of Bio and Brain Engineering KAIST Profile: Kisoo Kim Ph.D. Candidate kisoo.kim1@kaist.ac.kr http://biophotonics.kaist.ac.kr/ Department of Bio and Brain Engineering KAIST (END)
2020.03.23 View 15110
3D Hierarchically Porous Nanostructured Catalyst Helps Efficiently Reduce CO2 - This new catalyst will bring CO2 one step closer to serving as a sustainable energy source. - KAIST researchers developed a three-dimensional (3D) hierarchically porous nanostructured catalyst with carbon dioxide (CO2) to carbon monoxide (CO) conversion rate up to 3.96 times higher than that of conventional nanoporous gold catalysts. This new catalyst helps overcome the existing limitations of the mass transport that has been a major cause of decreases in the CO2 conversion rate, holding a strong promise for the large-scale and cost-effective electrochemical conversion of CO2 into useful chemicals. As CO2 emissions increase and fossil fuels deplete globally, reducing and converting CO2 to clean energy electrochemically has attracted a great deal of attention as a promising technology. Especially due to the fact that the CO2 reduction reaction occurs competitively with hydrogen evolution reactions (HER) at similar redox potentials, the development of an efficient electrocatalyst for selective and robust CO2 reduction reactions has remained a key technological issue. Gold (Au) is one of the most commonly used catalysts in CO2 reduction reactions, but the high cost and scarcity of Au pose obstacles for mass commercial applications. The development of nanostructures has been extensively studied as a potential approach to improving the selectivity for target products and maximizing the number of active stable sites, thus enhancing the energy efficiency. However, the nanopores of the previously reported complex nanostructures were easily blocked by gaseous CO bubbles during aqueous reactions. The CO bubbles hindered mass transport of the reactants through the electrolyte, resulting in low CO2 conversion rates. In the study published in the Proceedings of the National Academy of Sciences of the USA (PNAS) on March 4, a research group at KAIST led by Professor Seokwoo Jeon and Professor Jihun Oh from the Department of Materials Science and Engineering designed a 3D hierarchically porous Au nanostructure with two different sizes of macropores and nanopores. The team used proximity-field nanopatterning (PnP) and electroplating techniques that are effective for fabricating the 3D well-ordered nanostructures. The proposed nanostructure, comprised of interconnected macroporous channels 200 to 300 nanometers (nm) wide and 10 nm nanopores, induces efficient mass transport through the interconnected macroporous channels as well as high selectivity by producing highly active stable sites from numerous nanopores. As a result, its electrodes show a high CO selectivity of 85.8% at a low overpotential of 0.264 V and efficient mass activity that is up to 3.96 times higher than that of de-alloyed nanoporous Au electrodes. “These results are expected to solve the problem of mass transfer in the field of similar electrochemical reactions and can be applied to a wide range of green energy applications for the efficient utilization of electrocatalysts,” said the researchers. This work was supported by the National Research Foundation (NRF) of Korea. Image credit: Professor Seokwoo Jeon and Professor Jihun Oh, KAIST Image usage restrictions: News organizations may use or redistribute this image, with proper attribution, as part of news coverage of this paper only. Publication: Hyun et al. (2020) Hierarchically porous Au nanostructures with interconnected channels for efficient mass transport in electrocatalytic CO2 reduction. Proceedings of the National Academy of Sciences of the USA (PNAS). Available online at https://doi.org/10.1073/pnas.1918837117 Profile: Seokwoo Jeon, PhD Professor jeon39@kaist.ac.kr http://fdml.kaist.ac.kr Department of Materials Science and Engineering (MSE) https://www.kaist.ac.kr Korea Advanced Institute of Science and Technology (KAIST)Daejeon, Republic of Korea Profile: Jihun Oh, PhD Associate Professor jihun.oh@kaist.ac.kr http://les.kaist.ac.kr Department of Materials Science and Engineering (MSE) Department of Energy, Environment, Water and Sustainability (EEWS) KAIST Profile: Gayea Hyun PhD Candidate cldywkd93@kaist.ac.kr http://fdml.kaist.ac.kr Flexible Devices and Metamaterials Laboratory (FDML) Department of Materials Science and Engineering (MSE) KAIST Profile: Jun Tae Song, PhD Assistant Professor song.juntae@cstf.kyushu-u.ac.jp http://www.cstf.kyushu-u.ac.jp/~ishihara-lab/ Department of Applied Chemistry https://www.kyushu-u.ac.jp Kyushu UniversityFukuoka, Japan (END)
2020.03.13 View 14849
Scientists Observe the Elusive Kondo Screening Cloud Scientists ended a 50-year quest by directly observing a quantum phenomenon An international research group of Professor Heung-Sun Sim has ended a 50-year quest by directly observing a quantum phenomenon known as a Kondo screening cloud. This research, published in Nature on March 11, opens a novel way to engineer spin screening and entanglement. According to the research, the cloud can mediate interactions between distant spins confined in quantum dots, which is a necessary protocol for semiconductor spin-based quantum information processing. This spin-spin interaction mediated by the Kondo cloud is unique since both its strength and sign (two spins favor either parallel or anti-parallel configuration) are electrically tunable, while conventional schemes cannot reverse the sign. This phenomenon, which is important for many physical phenomena such as dilute magnetic impurities and spin glasses, is essentially a cloud that masks magnetic impurities in a material. It was known to exist but its spatial extension had never been observed, creating controversy over whether such an extension actually existed. Magnetism arises from a property of electrons known as spin, meaning that they have angular momentum aligned in one of either two directions, conventionally known as up and down. However, due to a phenomenon known as the Kondo effect, the spins of conduction electrons—the electrons that flow freely in a material—become entangled with a localized magnetic impurity, and effectively screen it. The strength of this spin coupling, calibrated as a temperature, is known as the Kondo temperature. The size of the cloud is another important parameter for a material containing multiple magnetic impurities because the spins in the cloud couple with one another and mediate the coupling between magnetic impurities when the clouds overlap. This happens in various materials such as Kondo lattices, spin glasses, and high temperature superconductors. Although the Kondo effect for a single magnetic impurity is now a text-book subject in many-body physics, detection of its key object, the Kondo cloud and its length, has remained elusive despite many attempts during the past five decades. Experiments using nuclear magnetic resonance or scanning tunneling microscopy, two common methods for understanding the structure of matter, have either shown no signature of the cloud, or demonstrated a signature only at a very short distance, less than 1 nanometer, so much shorter than the predicted cloud size, which was in the micron range. In the present study, the authors observed a Kondo screening cloud formed by an impurity defined as a localized electron spin in a quantum dot—a type of “artificial atom”—coupled to quasi-one-dimensional conduction electrons, and then used an interferometer to measure changes in the Kondo temperature, allowing them to investigate the presence of a cloud at the interferometer end. Essentially, they slightly perturbed the conduction electrons at a location away from the quantum dot using an electrostatic gate. The wave of conducting electrons scattered by this perturbation returned back to the quantum dot and interfered with itself. This is similar to how a wave on a water surface being scattered by a wall forms a stripe pattern. The Kondo cloud is a quantum mechanical object which acts to preserve the wave nature of electrons inside the cloud. Even though there is no direct electrostatic influence of the perturbation on the quantum dot, this interference modifies the Kondo signature measured by electron conductance through the quantum dot if the perturbation is present inside the cloud. In the study, the researchers found that the length as well as the shape of the cloud is universally scaled by the inverse of the Kondo temperature, and that the cloud’s size and shape were in good agreement with theoretical calculations. Professor Sim at the Department of Physics proposed the method for detecting the Kondo cloud in the co-research with the RIKEN Center for Emergent Matter Science, the City University of Hong Kong, the University of Tokyo, and Ruhr University Bochum in Germany. Professor Sim said, “The observed spin cloud is a micrometer-size object that has quantum mechanical wave nature and entanglement. This is why the spin cloud has not been observed despite a long search. It is remarkable in a fundamental and technical point of view that such a large quantum object can now be created, controlled, and detected. Dr. Michihisa Yamamoto of the RIKEN Center for Emergent Matter Science also said, “It is very satisfying to have been able to obtain real space image of the Kondo cloud, as it is a real breakthrough for understanding various systems containing multiple magnetic impurities. The size of the Kondo cloud in semiconductors was found to be much larger than the typical size of semiconductor devices.” Publication: Borzenets et al. (2020) Observation of the Kondo screening cloud. Nature, 579. pp.210-213. Available online at https://doi.org/10.1038/s41586-020-2058-6 Profile: Heung-Sun Sim, PhD Professor hssim@kaist.ac.kr https://qet.kaist.ac.kr/ Quantum Electron Correlation & Transport Theory Group (QECT Lab) https://qc.kaist.ac.kr/index.php/group1/ Center for Quantum Coherence In COndensed Matter Department of Physics https://www.kaist.ac.kr Korea Advanced Institute of Science and Technology (KAIST) Daejeon, Republic of Korea
2020.03.13 View 13179
A Single Biological Factor Predicts Distinct Cortical Organizations across Mammalian Species -A KAIST team’s mathematical sampling model shows that retino-cortical mapping is a prime determinant in the topography of cortical organization.- Researchers have explained how visual cortexes develop uniquely across the brains of different mammalian species. A KAIST research team led by Professor Se-Bum Paik from the Department of Bio and Brain Engineering has identified a single biological factor, the retino-cortical mapping ratio, that predicts distinct cortical organizations across mammalian species. This new finding has resolved a long-standing puzzle in understanding visual neuroscience regarding the origin of functional architectures in the visual cortex. The study published in Cell Reports on March 10 demonstrates that the evolutionary variation of biological parameters may induce the development of distinct functional circuits in the visual cortex, even without species-specific developmental mechanisms. In the primary visual cortex (V1) of mammals, neural tuning to visual stimulus orientation is organized into one of two distinct topographic patterns across species. While primates have columnar orientation maps, a salt-and-pepper type organization is observed in rodents. For decades, this sharp contrast between cortical organizations has spawned fundamental questions about the origin of functional architectures in the V1. However, it remained unknown whether these patterns reflect disparate developmental mechanisms across mammalian taxa, or simply originate from variations in biological parameters under a universal development process. To identify a determinant predicting distinct cortical organizations, Professor Paik and his researchers Jaeson Jang and Min Song examined the exact condition that generates columnar and salt-and-pepper organizations, respectively. Next, they applied a mathematical model to investigate how the topographic information of the underlying retinal mosaics pattern could be differently mapped onto a cortical space, depending on the mapping condition. The research team proved that the retino-cortical feedforwarding mapping ratio appeared to be correlated to the cortical organization of each species. In the model simulations, the team found that distinct cortical circuitries can arise from different V1 areas and retinal ganglion cell (RGC) mosaic sizes. The team’s mathematical sampling model shows that retino-cortical mapping is a prime determinant in the topography of cortical organization, and this prediction was confirmed by neural parameter analysis of the data from eight phylogenetically distinct mammalian species. Furthermore, the researchers proved that the Nyquist sampling theorem explains this parametric division of cortical organization with high accuracy. They showed that a mathematical model predicts that the organization of cortical orientation tuning makes a sharp transition around the Nyquist sampling frequency, explaining why cortical organizations can be observed in either columnar or salt-and-pepper organizations, but not in intermediates between these two stages. Professor Paik said, “Our findings make a significant impact for understanding the origin of functional architectures in the visual cortex of the brain, and will provide a broad conceptual advancement as well as advanced insights into the mechanism underlying neural development in evolutionarily divergent species.” He continued, “We believe that our findings will be of great interest to scientists working in a wide range of fields such as neuroscience, vision science, and developmental biology.” This work was supported by the National Research Foundation of Korea (NRF). Image credit: Professor Se-Bum Paik, KAIST Image usage restrictions: News organizations may use or redistribute this image, with proper attribution, as part of news coverage of this paper only. Publication: Jaeson Jang, Min Song, and Se-Bum Paik. (2020). Retino-cortical mapping ratio predicts columnar and salt-and-pepper organization in mammalian visual cortex. Cell Reports. Volume 30. Issue 10. pp. 3270-3279. Available online at https://doi.org/10.1016/j.celrep.2020.02.038 Profile: Se-Bum Paik Assistant Professor sbpaik@kaist.ac.kr http://vs.kaist.ac.kr/ VSNN Laboratory Department of Bio and Brain Engineering Program of Brain and Cognitive Engineering http://kaist.ac.kr Korea Advanced Institute of Science and Technology (KAIST) Daejeon, Republic of Korea Profile: Jaeson Jang Ph.D. Candidate jaesonjang@kaist.ac.kr Department of Bio and Brain Engineering, KAIST Profile: Min Song Ph.D. Candidate night@kaist.ac.kr Program of Brain and Cognitive Engineering, KAIST (END)
2020.03.11 View 11656
New Catalyst Recycles Greenhouse Gases into Fuel and Hydrogen Gas < Professor Cafer T. Yavuz (left), PhD Candidate Youngdong Song (center), and Researcher Sreerangappa Ramesh (right) > Scientists have taken a major step toward a circular carbon economy by developing a long-lasting, economical catalyst that recycles greenhouse gases into ingredients that can be used in fuel, hydrogen gas, and other chemicals. The results could be revolutionary in the effort to reverse global warming, according to the researchers. The study was published on February 14 in Science. “We set out to develop an effective catalyst that can convert large amounts of the greenhouse gases carbon dioxide and methane without failure,” said Cafer T. Yavuz, paper author and associate professor of chemical and biomolecular engineering and of chemistry at KAIST. The catalyst, made from inexpensive and abundant nickel, magnesium, and molybdenum, initiates and speeds up the rate of reaction that converts carbon dioxide and methane into hydrogen gas. It can work efficiently for more than a month. This conversion is called ‘dry reforming’, where harmful gases, such as carbon dioxide, are processed to produce more useful chemicals that could be refined for use in fuel, plastics, or even pharmaceuticals. It is an effective process, but it previously required rare and expensive metals such as platinum and rhodium to induce a brief and inefficient chemical reaction. Other researchers had previously proposed nickel as a more economical solution, but carbon byproducts would build up and the surface nanoparticles would bind together on the cheaper metal, fundamentally changing the composition and geometry of the catalyst and rendering it useless. “The difficulty arises from the lack of control on scores of active sites over the bulky catalysts surfaces because any refinement procedures attempted also change the nature of the catalyst itself,” Yavuz said. The researchers produced nickel-molybdenum nanoparticles under a reductive environment in the presence of a single crystalline magnesium oxide. As the ingredients were heated under reactive gas, the nanoparticles moved on the pristine crystal surface seeking anchoring points. The resulting activated catalyst sealed its own high-energy active sites and permanently fixed the location of the nanoparticles — meaning that the nickel-based catalyst will not have a carbon build up, nor will the surface particles bind to one another. “It took us almost a year to understand the underlying mechanism,” said first author Youngdong Song, a graduate student in the Department of Chemical and Biomolecular Engineering at KAIST. “Once we studied all the chemical events in detail, we were shocked.” The researchers dubbed the catalyst Nanocatalysts on Single Crystal Edges (NOSCE). The magnesium-oxide nanopowder comes from a finely structured form of magnesium oxide, where the molecules bind continuously to the edge. There are no breaks or defects in the surface, allowing for uniform and predictable reactions. “Our study solves a number of challenges the catalyst community faces,” Yavuz said. “We believe the NOSCE mechanism will improve other inefficient catalytic reactions and provide even further savings of greenhouse gas emissions.” This work was supported, in part, by the Saudi-Aramco-KAIST CO2 Management Center and the National Research Foundation of Korea. Other contributors include Ercan Ozdemir, Sreerangappa Ramesh, Aldiar Adishev, and Saravanan Subramanian, all of whom are affiliated with the Graduate School of Energy, Environment, Water and Sustainability at KAIST; Aadesh Harale, Mohammed Albuali, Bandar Abdullah Fadhel, and Aqil Jamal, all of whom are with the Research and Development Center in Saudi Arabia; and Dohyun Moon and Sun Hee Choi, both of whom are with the Pohang Accelerator Laboratory in Korea. Ozdemir is also affiliated with the Institute of Nanotechnology at the Gebze Technical University in Turkey; Fadhel and Jamal are also affiliated with the Saudi-Armco-KAIST CO2 Management Center in Korea. <Newly developed catalyst that recycles greenhouse gases into ingredients that can be used in fuel, hydrogen gas and other chemicals.> Publication: Song et al. (2020) Dry reforming of methane by stable Ni–Mo nanocatalysts on single-crystalline MgO. Science, Vol. 367, Issue 6479, pp. 777-781. Available online at http://dx.doi.org/10.1126/science.aav2412 Profile: Prof. Cafer T. Yavuz, MA, PhD yavuz@kaist.ac.kr http://yavuz.kaist.ac.kr/ Associate Professor Oxide and Organic Nanomaterials for the Environment (ONE) Laboratory Graduate School of Energy, Environment, Water and Sustainability (EEWS) Korea Advanced Institute of Science and Technology (KAIST) http://kaist.ac.kr Daejeon, Republic of Korea Profile: Youngdong Song ydsong88@kaist.ac.kr Ph.D. Candidate Department of Chemical and Biomolecular Engineering Korea Advanced Institute of Science and Technology (KAIST) http://kaist.ac.kr Daejeon, Republic of Korea (END)
2020.02.17 View 14965
What Fuels a “Domino Effect” in Cancer Drug Resistance? KAIST researchers have identified mechanisms that relay prior acquired resistance to the first-line chemotherapy to the second-line targeted therapy, fueling a “domino effect” in cancer drug resistance. Their study featured in the February 7 edition of Science Advances suggests a new strategy for improving the second-line setting of cancer treatment for patients who showed resistance to anti-cancer drugs. Resistance to cancer drugs is often managed in the clinic by chemotherapy and targeted therapy. Unlike chemotherapy that works by repressing fast-proliferating cells, targeted therapy blocks a single oncogenic pathway to halt tumor growth. In many cases, targeted therapy is engaged as a maintenance therapy or employed in the second-line after front-line chemotherapy. A team of researchers led by Professor Yoosik Kim from the Department of Chemical and Biomolecular Engineering and the KAIST Institute for Health Science and Technology (KIHST) has discovered an unexpected resistance signature that occurs between chemotherapy and targeted therapy. The team further identified a set of integrated mechanisms that promotes this kind of sequential therapy resistance. “There have been multiple clinical accounts reflecting that targeted therapies tend to be least successful in patients who have exhausted all standard treatments,” said the first author of the paper Mark Borris D. Aldonza. He continued, “These accounts ignited our hypothesis that failed responses to some chemotherapies might speed up the evolution of resistance to other drugs, particularly those with specific targets.” Aldonza and his colleagues extracted large amounts of drug-resistance information from the open-source database the Genomics of Drug Sensitivity in Cancer (GDSC), which contains thousands of drug response data entries from various human cancer cell lines. Their big data analysis revealed that cancer cell lines resistant to chemotherapies classified as anti-mitotic drugs (AMDs), toxins that inhibit overacting cell division, are also resistant to a class of targeted therapies called epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs). In all of the cancer types analyzed, more than 84 percent of those resistant to AMDs, representatively ‘paclitaxel’, were also resistant to at least nine EGFR-TKIs. In lung, pancreatic, and breast cancers where paclitaxel is often used as a first-line, standard-of-care regimen, greater than 92 percent showed resistance to EGFR-TKIs. Professor Kim said, “It is surprising to see that such collateral resistance can occur specifically between two chemically different classes of drugs.” To figure out how failed responses to paclitaxel leads to resistance to EGFR-TKIs, the team validated co-resistance signatures that they found in the database by generating and analyzing a subset of slow-doubling, paclitaxel-resistant cancer models called ‘persisters’. The results demonstrated that paclitaxel-resistant cancers remodel their stress response by first becoming more stem cell-like, evolving the ability to self-renew to adapt to more stressful conditions like drug exposures. More surprisingly, when the researchers characterized the metabolic state of the cells, EGFR-TKI persisters derived from paclitaxel-resistant cancer cells showed high dependencies to energy-producing processes such as glycolysis and glutaminolysis. “We found that, without an energy stimulus like glucose, these cells transform to becoming more senescent, a characteristic of cells that have arrested cell division. However, this senescence is controlled by stem cell factors, which the paclitaxel-resistant cancers use to escape from this arrested state given a favorable condition to re-grow,” said Aldonza. Professor Kim explained, “Before this research, there was no reason to expect that acquiring the cancer stem cell phenotype that dramatically leads to a cascade of changes in cellular states affecting metabolism and cell death is linked with drug-specific sequential resistance between two classes of therapies.” He added, “The expansion of our work to other working models of drug resistance in a much more clinically-relevant setting, perhaps in clinical trials, will take on increasing importance, as sequential treatment strategies will continue to be adapted to various forms of anti-cancer therapy regimens.” This study was supported by the Basic Science Research Program of the National Research Foundation of Korea (NRF-2016R1C1B2009886), and the KAIST Future Systems Healthcare Project (KAISTHEALTHCARE42) funded by the Korean Ministry of Science and ICT (MSIT). Undergraduate student Aldonza participated in this research project and presented the findings as the lead author as part of the Undergraduate Research Participation (URP) Program at KAIST. < Figure 1. Schematic overview of the study. > < Figure 2. Big data analysis revealing co-resistance signatures between classes of anti-cancer drugs. > Publication: Aldonza et al. (2020) Prior acquired resistance to paclitaxel relays diverse EGFR-targeted therapy persistence mechanisms. Science Advances, Vol. 6, No. 6, eaav7416. Available online at http://dx.doi.org/10.1126/sciadv.aav7416 Profile: Prof. Yoosik Kim, MA, PhD ysyoosik@kaist.ac.kr https://qcbio.kaist.ac.kr/ Assistant Professor Bio Network Analysis Laboratory Department of Chemical and Biomolecular Engineering Korea Advanced Institute of Science and Technology (KAIST) http://kaist.ac.kr Daejeon, Republic of Korea Profile: Mark Borris D. Aldonza borris@kaist.ac.kr Undergraduate Student Department of Biological Sciences Korea Advanced Institute of Science and Technology (KAIST) http://kaist.ac.kr Daejeon, Republic of Korea (END)
2020.02.10 View 11583
Professor Sung Yong Kim Elected as the Chair of PICES MONITOR < Professor Sung Yong Kim > Professor Sung Yong Kim from the Department of Mechanical Engineering was elected as the chair of the Technical Committee on Monitoring (MONITOR) of the North Pacific Marine Science Organization (PICES). PICES is an intergovernmental marine science organization that was established in 1992 through a collaboration between six North Pacific nations including South Korea, Russia, the United States, Japan, China, and Canada to exchange and discuss research on the Pacific waters. Its headquarters is located in Canada and the organization consists of seven affiliated maritime science and marine technology committees. Professor Kim was elected as the chair of the technical committee that focuses on monitoring and will be part of the Science Board as an ex-officio member. His term will last three years from November 2019. Professor Kim was recognized for his academic excellence, expertise, and leadership among oceanographers both domestically and internationally. Professor Kim will also participate as an academia civilian committee member of the Maritime and Fisheries Science and Technology Committee under the Korean Ministry of Oceans and Fisheries for two years from December 18, 2019. He stated, “I will give my full efforts to broaden Korean oceanography research by participating in maritime leadership positions at home and abroad, and help South Korea become a maritime powerhouse.” (END)
2019.12.22 View 7568
Professor Shin-Hyun Kim Receives the Young Scientist Award Professor Shin-Hyun Kim from the Department of Chemical and Biomolecular Engineering received the Young Scientist Award from the Korean Academy of Science and Technology. The Young Scientist Award is presented to a promising young Korean scientist under the age of 40 who shows significant potential, passion, and remarkable achievement. Professor Kim was lauded for his research of intelligent soft materials. By applying his research, he developed a capsule sensor material that can not only be used for sensors, but also for displays, color aesthetics, anti-counterfeit technology, residual drug detection, and more. The award ceremony took place on December 14 at the Gwacheon National Science Museum. The Korean minister of Science and ICT delivered words of encouragement, reminding everyone that “the driving force behind creative performance of scientists is the provision of continuous support.” He added, “Researchers of Korea deserve greater public attention and support.” (END)
2019.12.21 View 6506
New Liquid Metal Wearable Pressure Sensor Created for Health Monitoring Applications Soft pressure sensors have received significant research attention in a variety of fields, including soft robotics, electronic skin, and wearable electronics. Wearable soft pressure sensors have great potential for the real-time health monitoring and for the early diagnosis of diseases. A KAIST research team led by Professor Inkyu Park from the Department of Mechanical Engineering developed a highly sensitive wearable pressure sensor for health monitoring applications. This work was reported in Advanced Healthcare Materials on November 21 as a front cover article. This technology is capable of sensitive, precise, and continuous measurement of physiological and physical signals and shows great potential for health monitoring applications and the early diagnosis of diseases. A soft pressure sensor is required to have high compliance, high sensitivity, low cost, long-term performance stability, and environmental stability in order to be employed for continuous health monitoring. Conventional solid-state soft pressure sensors using functional materials including carbon nanotubes and graphene have showed great sensing performance. However, these sensors suffer from limited stretchability, signal drifting, and long-term instability due to the distance between the stretchable substrate and the functional materials. To overcome these issues, liquid-state electronics using liquid metal have been introduced for various wearable applications. Of these materials, Galinstan, a eutectic metal alloy of gallium, indium, and tin, has great mechanical and electrical properties that can be employed in wearable applications. But today’s liquid metal-based pressure sensors have low-pressure sensitivity, limiting their applicability for health monitoring devices. The research team developed a 3D-printed rigid microbump array-integrated, liquid metal-based soft pressure sensor. With the help of 3D printing, the integration of a rigid microbump array and the master mold for a liquid metal microchannel could be achieved simultaneously, reducing the complexity of the manufacturing process. Through the integration of the rigid microbump and the microchannel, the new pressure sensor has an extremely low detection limit and enhanced pressure sensitivity compared to previously reported liquid metal-based pressure sensors. The proposed sensor also has a negligible signal drift over 10,000 cycles of pressure, bending, and stretching and exhibited excellent stability when subjected to various environmental conditions. These performance outcomes make it an excellent sensor for various health monitoring devices. First, the research team demonstrated a wearable wristband device that can continuously monitor one’s pulse during exercise and be employed in a noninvasive cuffless BP monitoring system based on PTT calculations. Then, they introduced a wireless wearable heel pressure monitoring system that integrates three 3D-BLiPS with a wireless communication module. Professor Park said, “It was possible to measure health indicators including pulse and blood pressure continuously as well as pressure of body parts using our proposed soft pressure sensor. We expect it to be used in health care applications, such as the prevention and the monitoring of the pressure-driven diseases such as pressure ulcers in the near future. There will be more opportunities for future research including a whole-body pressure monitoring system related to other physical parameters.” This work was supported by a National Research Foundation of Korea (NRF) grant funded by the Ministry of Science and ICT. < Figure 1. The front cover image of Advanced Healthcare Materials, Volume 8, Issue 22. > < Figure 2. Highly sensitive liquid metal-based soft pressure sensor integrated with 3D-printed microbump array. > < Figure 3. High pressure sensitivity and reliable sensing performances of the proposed sensor and wireless heel pressure monitoring application. > -ProfileProfessor Inkyu ParkMicro/Nano Transducers Laboratoryhttp://mintlab1.kaist.ac.kr/ Department of Mechanical EngineeringKAIST
2019.12.20 View 11888
Team Geumo Wins Consecutive Victories in K-Cyber Security Challenge < Professor Sang Kil Cha > < Masters Candidate Kangsu Kim and Researcher Corentin Soulet > Team Geumo, led by Professor Sang Kil Cha from the Graduate School of Information Security, won the K-Cyber Security Challenge in the AI-based automatic vulnerability detection division for two consecutive years in 2018 and 2019. The K-Cyber Security Challenge is an inter-machine hacking competition. Participants develop and operate AI-based systems that are capable of independently identifying software vulnerabilities and gaining operating rights through hacking. The K-Cyber Security Challenge, inspired by the US Cyber Grand Challenge launched by the Defense Advanced Research Projects Agency (DARPA), is hosted by the Ministry of Science and ICT and organized by the Korea Internet and Security Agency. Researcher Corentin Soulet of the School of Computing and master’s student Kangsu Kim of the Graduate School of Information Security teamed up for the competition. Professor Cha, who has led the research on software and systems security since his days at Carnegie Mellon University, succeeded in establishing a world-class system using domestic technology. In a recent collaboration with the Cyber Security Research Center, Professor Cha achieved a ten-fold increase in the speed of binary analysis engines, a key component of AI-based hacking systems. For this accomplishment, he received the Best Paper Award at the 2019 Network and Distributed System Security Workshop on Binary Analysis Research (NDSS BAR). Kangsu Kim said, "It is a great honor to win the competition two years in a row. I will continue to work hard and apply my knowledge to serve society.” (END)
2019.12.20 View 7977
Professor Il-Doo Kim Named Scientist of the Year by the Journalists Professor Il-Doo Kim from the Department of Materials Science and Engineering was named the 2019 Scientist of the Year by Korean science journalists. The award was conferred at the 2019 Science Press Night ceremony of the Korea Science Journalists Association (KSJA) on November 29. Professor Kim focuses on developing nanofiber gas sensors for diagnosing diseases in advance by analyzing exhaled biomarkers with electrospinning technology. His outstanding research was praised and selected as one of the top 10 nanotechnology of 2019 by the Korea Nano Technology Research Society (KoNTRS), the Ministry of Science and ICT (MSIT), and the Ministry of Trade, Industry and Energy (MOTIE). Professor Kim was honored with the QIAN Baojun Fiber Award, which is awarded every two years by Donghua University in Shanghai, China to recognize outstanding contributions in fiber science and technology. Professor Kim was also elected as an academician of the Asia Pacific Academy of Materials (APAM) on November 21 in Guangzhou, China. In May, Professor Kim was appointed as an associate editor of ACS Nano, a leading international research journal in the field of nanoscience. In his editorial published in the May issue of ACS Nano, Professor Kim introduced and shared the history of KAIST and its vision for the future with other members of the journal. He hopes this will help with promoting a closer relationship between the members of the journal and KAIST moving forward. “Above all,” he said in his acceptance speech, “the greatest news for me as an educator is that the first PhD graduate from our lab, Dr. Seonjin Choi, was appointed as the youngest professor in the Division of Materials Science and Engineering at Hanyang University on September 1.”
2019.12.17 View 9132

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