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KAIST Develops Ultrathin Polymer Insulators Key to Low-Power Soft Electronics
Using an initiated chemical vapor deposition technique, the research team created an ultrathin polymeric insulating layer essential in realizing transistors with flexibility and low power consumption. This advance is expected to accelerate the commercialization of wearable and soft electronics. A group of researchers at the Korea Advanced Institute of Science and Technology (KAIST) developed a high-performance ultrathin polymeric insulator for field-effect transistors (FETs). The researchers used vaporized monomers to form polymeric films grown conformally on various surfaces including plastics to produce a versatile insulator that meets a wide range of requirements for next-generation electronic devices. Their research results were published online in Nature Materials on March 9th, 2015. FETs are an essential component for any modern electronic device used in our daily life from cell phones and computers, to flat-panel displays. Along with three electrodes (gate, source, and drain), FETs consist of an insulating layer and a semiconductor channel layer. The insulator in FETs plays an important role in controlling the conductance of the semiconductor channel and thus current flow within the translators. For reliable and low-power operation of FETs, electrically robust, ultrathin insulators are essential. Conventionally, such insulators are made of inorganic materials (e.g., oxides and nitrides) built on a hard surface such as silicon or glass due to their excellent insulating performance and reliability. However, these insulators were difficult to implement into soft electronics due to their rigidity and high process temperature. In recent years, many researchers have studied polymers as promising insulating materials that are compatible with soft unconventional substrates and emerging semiconductor materials. The traditional technique employed in developing a polymer insulator, however, had the limitations of low surface coverage at ultra-low thickness, hindering FETs adopting polymeric insulators from operating at low voltage. A KAIST research team led by Professor Sung Gap Im of the Chemical and Biomolecular Engineering Department and Professor Seunghyup Yoo and Professor Byung Jin Cho of the Electrical Engineering Department developed an insulating layer of organic polymers, “pV3D3,” that can be greatly scaled down, without losing its ideal insulating properties, to a thickness of less than 10 nanometers (nm) using the all-dry vapor-phase technique called the “initiated chemical vapor deposition (iCVD).” The iCVD process allows gaseous monomers and initiators to react with each other in a low vacuum condition, and as a result, conformal polymeric films with excellent insulating properties are deposited on a substrate. Unlike the traditional technique, the surface-growing character of iCVD can overcome the problems associated with surface tension and produce highly uniform and pure ultrathin polymeric films over a large area with virtually no surface or substrate limitations. Furthermore, most iCVD polymers are created at room temperature, which lessens the strain exerted upon and damage done to the substrates. With the pV3D3 insulator, the research team built low-power, high-performance FETs based on various semiconductor materials such as organics, graphene, and oxides, demonstrating the pV3D3 insulator’s wide range of material compatibility. They also manufactured a stick-on, removable electronic component using conventional packaging tape as a substrate. In collaboration with Professor Yong-Young Noh from Dongguk University in Korea, the team successfully developed a transistor array on a large-scale flexible substrate with the pV3D3 insulator. Professor Im said, “The down-scalability and wide range of compatibility observed with iCVD-grown pV3D3 are unprecedented for polymeric insulators. Our iCVD pV3D3 polymeric films showed an insulating performance comparable to that of inorganic insulating layers, even when their thickness were scaled down to sub-10 nm. We expect our development will greatly benefit flexible or soft electronics, which will play a key role in the success of emerging electronic devices such as wearable computers.” The title of the research paper is “Synthesis of ultrathin polymer insulating layers by initiated chemical vapor deposition for low-power soft electronics” (Digital Object Identifier (DOI) number is 10.1038/nmat4237). Picture 1: A schematic image to show how the initiated chemical vapor deposition (iCVD) technique produces pV3D3 polymeric films: (i) introduction of vaporized monomers and initiators, (ii) activation of initiators to thermally dissociate into radicals, (iii) adsorption of monomers and initiator radicals onto a substrate, and (iv) transformation of free-radical polymerization into pV3D3 thin films. Picture 2: This is a transistor array fabricated on a large scale, highly flexible substrate with pV3D3 polymeric films. Picture 3: This photograph shows an electronic component fabricated on a conventional packaging tape, which is attachable or detachable, with pV3D3 polymeric films embedded.
2015.03.10
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System Approach Using Metabolite Structural Similarity Toward TOM Suggested
A Korean research team at KAIST suggests that a system approach using metabolite structural similarity helps to elucidate the mechanisms of action of traditional oriental medicine. Traditional oriental medicine (TOM) has been practiced in Asian countries for centuries, and is gaining increasing popularity around the world. Despite its efficacy in various symptoms, TOM has been practiced without precise knowledge of its mechanisms of action. Use of TOM largely comes from empirical knowledge practiced over a long period of time. The fact that some of the compounds found in TOM have led to successful modern drugs such as artemisinin for malaria and taxol (Paclitaxel) for cancer has spurred modernization of TOM. A research team led by Sang-Yup Lee at KAIST has focused on structural similarities between compounds in TOM and human metabolites to help explain TOM’s mechanisms of action. This systems approach using structural similarities assumes that compounds which are structurally similar to metabolites could affect relevant metabolic pathways and reactions by biosynthesizing structurally similar metabolites. Structural similarity analysis has helped to identify mechanisms of action of TOM. This is described in a recent study entitled “A systems approach to traditional oriental medicine,” published online in Nature Biotechnology on March 6, 2015. In this study, the research team conducted structural comparisons of all the structurally known compounds in TOM and human metabolites on a large-scale. As a control, structures of all available approved drugs were also compared against human metabolites. This structural analysis provides two important results. First, the identification of metabolites structurally similar to TOM compounds helped to narrow down the candidate target pathways and reactions for the effects from TOM compounds. Second, it suggested that a greater fraction of all the structurally known TOM compounds appeared to be more similar to human metabolites than the approved drugs. This second finding indicates that TOM has a great potential to interact with diverse metabolic pathways with strong efficacy. This finding, in fact, shows that TOM compounds might be advantageous for the multitargeting required to cure complex diseases. “Once we have narrowed down candidate target pathways and reactions using this structural similarity approach, additional in silico tools will be necessary to characterize the mechanisms of action of many TOM compounds at a molecular level,” said Hyun Uk Kim, a research professor at KAIST. TOM’s multicomponent, multitarget approach wherein multiple components show synergistic effects to treat symptoms is highly distinctive. The researchers investigated previously observed effects recorded since 2000 of a set of TOM compounds with known mechanisms of action. TOM compounds’ synergistic combinations largely consist of a major compound providing the intended efficacy to the target site and supporting compounds which maximize the efficacy of the major compound. In fact, such combination designs appear to mirror the Kun-Shin-Choa-Sa design principle of TOM. That principle, Kun-Shin-Choa-Sa (君臣佐使 or Jun-Chen-Zuo-Shi in Chinese) literally means “king-minister-assistant-ambassador.” In ancient East Asian medicine, treating human diseases and taking good care of the human body are analogous to the politics of governing a nation. Just as good governance requires that a king be supported by ministers, assistants and/or ambassadors, treating diseases or good care of the body required the combined use of herbal medicines designed based on the concept of Kun-Shin-Choa-Sa. Here, the Kun (king or the major component) indicates the major medicine (or herb) conveying the major drug efficacy, and is supported by three different types of medicines: the Shin (minister or the complementary component) for enhancing and/or complementing the efficacy of the Kun, Choa (assistant or the neutralizing component) for reducing any side effects caused by the Kun and reducing the minor symptoms accompanying major symptom, and Sa (ambassador or the delivery/retaining component) which facilitated the delivery of the Kun to the target site, and retaining the Kun for prolonged availability in the cells. The synergistic combinations of TOM compounds reported in the literature showed four different types of synergisms: complementary action (similar to Kun-Shin), neutralizing action (similar to Kun-Choa), facilitating action or pharmacokinetic potentiation (both similar to Kun-Choa or Kun-Sa). Additional structural analyses for these compounds with synergism show that they appeared to affect metabolism of amino acids, co-factors and vitamins as major targets. Professor Sang Yup Lee remarks, “This study lays a foundation for the integration of traditional oriental medicine with modern drug discovery and development. The systems approach taken in this analysis will be used to elucidate mechanisms of action of unknown TOM compounds which will then be subjected to rigorous validation through clinical and in silico experiments.” Sources: Kim, H.U. et al. “A systems approach to traditional oriental medicine.” Nature Biotechnology. 33: 264-268 (2015). This work was supported by the Bio-Synergy Research Project (2012M3A9C4048759) of the Ministry of Science, ICT and Future Planning through the National Research Foundation. This work was also supported by the Novo Nordisk Foundation. The picture below presents the structural similarity analysis of comparing compounds in traditional oriental medicine and those in all available approved drugs against the structures of human metabolites.
2015.03.09
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KAIST Develops Subminiature, Power-Efficient Air Pollution Sensing Probe
Professor Inkyu Park and his research team from the Department of Mechanical Engineering at KAIST have developed a subminiature, power-efficient air-pollution sensing probe that can be applied to mobile devices. Their research findings were published online in the January 30th issue of Scientific Reports. As air pollution has increased, people have taken greater interest in health care. The developed technology could allow people to measure independently the air pollution level of their surrounding environments. Previous instruments used to measure air pollution levels were bulky and consumed a lot of power. They also often produced inaccurate results when measuring air pollution in which different toxic gases were mixed. These problems could not be resolved with existing semiconductor manufacturing process. Using local temperature field control technology, Professor Park’s team succeeded in integrating multiple heterogeneous nanomaterials and fitting them onto a small, low-power electronic chip. This microheating sensor can heat microscale regions through local hydrothermal synthesis. Because it requires a miniscale amount of nanomaterials to manufacture, the sensor is most suitable for mobile devices. Professor Park said, “Our research will contribute to the development of convergence technology in such field as air pollution sensing probes, biosensors, electronic devices, and displays.” The team's research was supported by the Ministry of Education and the Ministry of Science, ICT and Future Planning, Republic of Korea. Figure 1 – The Concept of Multiple Nanomaterial Device and Numerical Simulation Results of Precursor Solutions Figure 2 - Multiple Nanomaterial Manufactured in a Microscale Region
2015.02.27
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An Advanced Method of DNA Nanostructure Formation Developed
Professor Tae-Young Yoon’s research team from the Department of Physics at KAIST has developed a new method to form DNA nanostructures by using magnetic tweezers to observe and to induce the formation of the structure in real time. Unlike traditional designs of "DNA origami" which relies on thermal or chemical annealing methods, the new technology utilizes a completely different dynamic in DNA folding. This allows the folding to be done within only ten minutes. Developed in 2006, the "DNA origami" allows a long skeleton of DNA to be folded into an arbitrary structure by using small stapler DNA pieces. This has been a prominent method in DNA nanotechnology. However, the traditional technology which adopts thermal processes could not control the DNA formation during the folding because every interaction among DNAs occurs simultaneously. Thus, the thermal processes, which take dozens of hours to complete, had to be repeated multiple times in order to find the optimal condition. The research team designed a DNA folding using uni-molecular magnetic tweezers that applied force to a single DNA molecule while measuring the state of the DNA. Through this technology, they were able to induce the formation of DNA nanostructure and observe it at the same time. During high temperature heat treatment, the first stage of conventional thermal processes, the internal structure of the long skeleton DNA untangles. To induce such state, after attaching one side of the skeleton DNA to the surface of glass and the other side to a magnetic material, the team unfolded the internal structure of the DNA by pulling the two sides apart with magnetic force. Unlike the conventional thermal processes, this method lets the stapler DNA swiftly adhere to the skeleton DNA within a minute because the sites are revealed at room temperature. After the stapler pieces connected to the skeleton, the team removed the magnetic force. Next, the structure folded through self-assembly as the stapler DNAs stuck to different sites on the skeleton DNA. Professor Yoon said, “With the existing thermal methods, we could not differentiate the reactions of the DNA because the response of each DNA pieces mutually interacted with each other.” He added that “Using the magnetic tweezers, we were able to sort the process of DNA nanostructure formation into a series of reactions of DNA molecules that are well known, and shorten the time taken for formation in only ten minutes.” He commented, “This nanostructure formation method will enable us to create more intricate and desirable DNA nanostructures by programming the folding of DNA origami structures.” Conducted by Dr. Woori Bae under the guidance of Professor Yoon, the research findings were published online in the December 4th issue of Nature Communications. Figure 1: Uni-molecular magnetic tweezers orchestrating the DNA nanostructure formation Figure 2: The evolution of DNA nanostructure formation using magnetic tweezers. The DNA nanostructure with a 21-nanometer size was formed in about eight minutes.
2015.01.06
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A Key Signal Transduction Pathway Switch in Cardiomyocyte Identified
A KAIST research team has identified the fundamental principle in deciding the fate of cardiomyocyte or heart muscle cells. They have determined that it depends on the degree of stimulus in β-adrenergic receptor signal transduction pathway in the cardiomyocyte to control cells' survival or death. The findings, the team hopes, can be used to treat various heart diseases including heart failure. The research was led by KAIST Department of Bio and Brain Engineering Chair Professor Kwang-Hyun Cho and conducted by Dr. Sung-Young Shin (lead author) and Ph.D. candidates Ho-Sung Lee and Joon-Hyuk Kang. The research was conducted jointly with GIST (Gwangju Institute of Science and Technology) Department of Biological Sciences Professor Do-Han Kim’s team. The research was supported by the Ministry of Science, ICT and Future Planning, Republic of Korea, and the National Research Foundation of Korea. The paper was published in Nature Communications on December 17, 2014 with the title, “The switching role of β-adrenergic receptor signalling in cell survival or death decision of cardiomyocytes.” The β-adrenergic receptor signal transduction pathway can promote cell survival (mediated by β2 receptors), but also can result in cell death by inducing toxin (mediated by β1 receptors) that leads to various heart diseases including heart failure. Past attempts to identify the fundamental principle in the fate determining process of cardiomyocyte based on β-adrenergic receptor signalling concluded without much success. The β-adrenergic receptor is a type of protein on the cell membrane of cardiomyocyte (heart muscle cell) that when stimulated by neurohormones such as epinephrine or norepinephrine would transduce signals making the cardiomyocyte contract faster and stronger. The research team used large-scale computer simulation analysis and systems biology to identify ERK* and ICER** signal transduction pathways mediated by a feed-forward circuit as a key molecular switch that decides between cell survival and death. Weak β-adrenergic receptor stimulations activate ERK signal transduction pathway, increasing Bcl-2*** protein expression to promote cardiomyocyte survival. On the other hand, strong β-adrenergic receptor stimulations activate ICER signal transduction pathway, reducing Bcl-2 protein expression to promote cardiomyocyte death. Researchers used a systems biology approach to identify the mechanism of B-blocker****, a common drug prescribed for heart failure. When cardiomyocyte is treated with β1 inhibitor, strong stimulation on β-adrenergic receptor increases Bcl-2 expression, improving the chance of cardiomyocyte survival, a cell protection effect. Professor Kwang-Hyun Cho said, “This research used systems biology, an integrated, convergence research of IT (information technology) and BT (biotechnology), to successfully identify the mechanism in deciding the fate of cardiomyocytes based on the β-adrenergic receptor signal transduction pathway for the first time. I am hopeful that this research will enable the control of cardiomyocyte survival and death to treat various heart diseases including heart failure.” Professor Cho’s team was the first to pioneer a new field of systems biology, especially concerning the complex signal transduction network involved in diseases. Their research is focused on modelling, analyzing simulations, and experimentally proving signal pathways. Professor Cho has published 140 articles in international journals including Cell, Science, and Nature. * ERK (Extracellular signal-regulated kinases): Signal transduction molecule involved in cell survival ** ICER (Inducible cAMP early repressor): Signal transduction molecule involved in cell death *** Bcl-2 (B-cell lymphoma 2): Key signal transduction molecule involved in promotion of cell survival **** β-blocker: Drug that acts as β-adrenergic receptor inhibitor known to slow the progression of heart failure, hence used most commonly in medicine. Picture: A schematic diagram for the β-AR signalling network
2015.01.05
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Broadband and Ultrathin Polarization Manipulators Developed
Professor Bumki Min from the Department of Mechanical Engineering at KAIST has developed a technology that can manipulate a polarized light in broadband operation with the use of a metamaterial. It is expected that this technology will lead to the development of broadband optical devices that can be applied to broadband communication and display. When an object or its structure is analyzed by using a polarized light such as a laser, the results are generally affected by the polarized state of the light. Therefore, in an optics laboratory, the light is polarized by various methods. In such cases, researchers employ wave plates or photoactive materials. However, the performance of these devices depend vastly on wavelength, and so they are not suitable to be used as a polarizer, especially in broadband. There were many attempts to make artificial materials that are very photoactive by using metamaterials which have a strong resonance. Nonetheless, because the materials had an unavoidable dispersion in the resonance frequency, they were not adequate for broadband operation. Professor Min’s research team arranged and connected helical metamaterials that are smaller than the wavelength of light. They verified theoretically and experimentally that polarized light can be constantly rotated regardless of the wavelength by super-thin materials that have thickness less than one-tenth of the wavelength of the light. The experiment which confirmed the theory was conducted in the microwave band. Broadband polarized rotational 3D metamaterials were found to rotate the polarized microwave within the range of 0.1 GHz to 40 GHz by 45 degrees regardless of its frequency. This nondispersive property is quite unnatural because it is difficult to find a material that does not change in a wide band. In addition, the research team materialized the broadband nondispersive polarized rotational property by designing the metamaterial in a way that it has chirality, which determines the number of rotations proportional to the wavelength. Professor Min said, “As the technology is able to manipulate ultrathin polarization of light in broadband, it will lead to the creation of ultra-shallow broadband optical devices.” Sponsored by the Ministry of Science, ICT and Future Planning of the Republic of Korea and the National Research Foundation of Korea, this research was led by a PhD candidate, Hyun-Sung Park, under the guidance of Professor Min. The research findings were published online in the November 17th issue of Nature Communications. Figure 1 – Broadband and Ultrathin Polarization Manipulators Produced by 3D Printer Figure 2 – Concept of Broadband and Ultrathin Polarization Manipulators
2014.12.03
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Structure of Neuron-Connecting Synaptic Adhesion Molecules Discovered
A research team has found the three-dimensional structure of synaptic adhesion molecules, which orchestrate synaptogenesis. The research findings also propose the mechanism of synapses in its initial formation. Some brain diseases such as obsessive compulsive disorder (OCD) or bipolar disorders arise from a malfunction of synapses. The team expects the findings to be applied in investigating pathogenesis and developing medicines for such diseases. The research was conducted by a Master’s candidate Kee Hun Kim, Professor Ji Won Um from Yonsei University, and Professor Beom Seok Park from Eulji University under the guidance of Professor Homin Kim from the Graduate School of Medical Science and Engineering, KAIST, and Professor Jaewon Ko from Yonsei University. Sponsored by the Ministry of Science, ICT and Future Planning and the National Research Foundation of Korea, the research findings were published online in the November 14th issue of Nature Communications. A protein that exists in the neuronal transmembrane, Slitrk, interacts with the presynaptic leukocyte common antigen-related receptor protein tyrosine phosphatases (LAR-RPTPs) and forms a protein complex. It is involved in the development of synapses in the initial stage, and balances excitatory and inhibitory signals of neurons. It is known that a disorder in those two proteins cause a malfunction of synapses, resulting in neuropsychosis such as autism, epilepsy, OCD, and bipolar disorders. However, because the structure as well as synaptogenic function of these proteins were not understood, the development of cures could not progress. The research team discovered the three-dimensional structure of two synaptic adhesion molecules like Slitrk and LAR-RPTPs and identified the regions of interaction through protein crystallography and transmission electron microscopy (TEM). Furthermore, they found that the formation of the synapse is induced after the combination of two synaptic adhesion molecules develops a cluster. Professor Kim said, “The research findings will serve as a basis of understanding the pathogenesis of brain diseases which arises from a malfunction of synaptic adhesion molecules. In particular, this is a good example in which collaboration between structural biology and neurobiology has led to a fruitful result.” Professor Ko commented that “this will give new directions to synaptic formation-related-researches by revealing the molecular mechanism of synaptic adhesion molecules.” Figure 1: Overview of the PTPd Ig1–3/Slitrk1 LRR1 complex. Figure 2: Representative negative-stained electron microscopy images of Slitrk1 Full ectodomain (yellow arrows indicate the horseshoe-shaped LRR domains). The typical horseshoe-shaped structures and the randomness of the relative positions of each LRR domain can be observed from the two-dimensional class averages displayed in the orange box. Figure 3: Model of the two-step presynaptic differentiation process mediated by the biding of Slitrks to LAR-RPTPs and subsequent lateral assembly of trans-synaptic LAR-RPTPs/Slitrik complexes.
2014.11.28
View 9478
Professor YongKeun Park Produces Undergraduate Students with International Achievements
Three undergraduate students under the supervision of Professor YongKeun Park from the Department of Physics, KAIST, have published papers in globally renowned academic journals. The most recent publication was made by YoungJu Jo, a senior in physics. Jo’s paper entitled “Angle-resolved light scattering of individual rod-shaped bacteria based on Fourier transform light scattering” was published in the May 28th edition of Scientific Reports. Analyzing bacteria is a very important task in the field of health and food hygiene, but using the conventional biochemical methods of analysis takes days. However, observation with Jo’s newly developed method using light scattering analyzes bacteria within a matter of seconds. SangYeon Cho from the Department of Chemistry also published papers in Cell (2012) and Nature (2013), respectively, under the guidance of Professor Park. SangYeon Cho’s outstanding research achievements were recognized by Harvard and MIT. He was accepted with a full scholarship to Harvard-MIT Health Sciences and Technology Graduate School. He will begin his graduate studies at Harvard-MIT this September. Last March, SeoEun Lee from the Department of Biology was the recipient of the Best Paper Award by the Optical Society of Korea. She plans to pursue a doctoral degree at the College of Physicians and Surgeons, Columbia University in New York. Professor Park said, “Undergraduate students, who are learning a variety of subjects concurrently, are at the most creative time of their lives. KAIST has offered many opportunities to undergraduate students to partake in various research programs.” - Picture (a) and (b): Rod-shaped bacteria’s phase image and light-scattering patterns - Picture (c): Quantitative analysis to illustrate the extraction of information from bacteria
2014.06.03
View 9452
KAIST Top in the Nature Publishing Index 2013 Asia-Pacific
The Nature Publishing Index 2013 Asia-Pacific has been released today. The index is a supplement to Nature, which measures the output of research articles from nations and institutes published in the 18 Nature-branded primary research journals over the calendar year. A press release from the Nature Publishing Group follows below: South Korea regains scientific impetus PRESS RELEASE FROM NATURE PUBLISHING GROUP Embargoed until 03.00 KST on Thursday 27 March 2014 South Korea ranks fourth for scientific research output in the region, according to the Nature Publishing Index 2013 Asia-Pacific released today. In 2013, the nation significantly increased its NPI output following a slight drop in 2012. Named a possible ‘one to watch’ by the supplement editors, with high levels of investment in science and technology announced by both government and private enterprise, its NPI output is growing faster than China’s. The Korea Advanced Institute of Science and Technology has risen two places to take top spot above Seoul National University, which has retained second place. Pohang University of Science and Technology has leapt from eighth to third, with a more-than-threefold increase in corrected count, adjusted for the proportional contribution of collaborative institutions. Last year’s number one, Yonsei University, could not maintain its exceptional 2012 NPI output and has dropped to seventh spot. It is now just above a newcomer, the Institute for Basic Science (IBS), funded as part of the government’s increased investment in basic science. IBS plans to open 50 research centres by 2017 and will no doubt provide increasing contributions in the next few years. To see the latest results for the region, and the Nature Publishing Index Global Top 100, visit the Index website at www.natureasia.com/en/publishing-index. The data posted on the website is updated every week with a moving window of 12 months of data.
2014.03.27
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Professor Sang-Ouk Kim Publishes Review Article in the Journal of "Nature Materials"
Nature Materials, a peer-reviewed scientific journal published by Nature Publishing Group, covers a range of topics within materials science from materials engineering and structural materials. The journal invited Professor Sang-Ouk Kim of Materials Science and Engineering at KAIST to contribute to the April issue of 2014. Professor Kim, together with his doctoral student, Ju-Young Kim, wrote a review article in the “News and Views” section of the journal, which was entitled “Liquid Crystals: Electric Fields Line Up Graphene Oxide.” The News and Views is a peer-reviewed section where an academic authority in a particular field reviews and evaluates papers published in the journal. In the article, Professor Kim reviewed a paper written by Jang-Kun Song et al. and highlighted important research outcomes such as the efficient electric field switching of graphene oxide (GO) liquid-crystals in low-concentration dispersions and the demonstration of a prototype of a GO liquid-crystal display. This technology could lead the development of a flexible display. Professor Kim is an eminent scholar who has reported for the first time in the world on the solvent-based graphene oxide liquid crystals formation in 2011. For the article, please go to: http://www.kaist.ac.kr/_prog/download.php?filename=Nature_Materials_Professor_Sang-Ouk_Kim_Apr_2014.pdf
2014.03.26
View 7718
A research paper by Professor Myung-Chul Choi reviewed in Science (February 28, 2014)
A research paper entitled “Transformation of taxol-stabilized microtubules into inverted tubulin tubules triggered by a tubulin conformation switch” was published in Nature Materials this year, dated January 19, 2014. Professor Myung-Chul Choi and Dr. Chae-Yeon Song from the Department of Bio and Brain Engineering at KAIST co-authored the paper together with researchers from the University of California in Santa Barbara and the Hebrew University of Jerusalem. Science, dated February 28, 2014, has recently reviewed the paper in its section called "Perspectives."
2014.03.13
View 7374
Spillover Phenomenon Identified Using Model Catalyst System
Researchers at KAIST have identified spillover phenomenon, which has remained controversial since its discovery in the early 1960s. KAIST Department of Chemical and Biomolecular Engineering’s Professor Min-Gi Choi and his team has explained the "spillover phenomenon," using their own model catalyst system where platinum is selectively located within the amorphous aluminosilicate. The research results were published on the 25th February online edition of Nature Communications. Spillover refers to a phenomenon that occurs when hydrogen atoms that have been activated on the surface of metals, such as platinum, move to the surface of the catalyst. It was predicted that this phenomenon can be used to design a catalyst with high activity and stability, and thus has been actively studied over the last 50 years. However, many cases of the known catalysts involved competing reactions on the exposed metal surface, which made it impossible to directly identify the presence and formation mechanism of spillover. The catalysts developed by the researchers at KAIST used platinum nanoparticles covered with aluminosilicate. This only allowed the hydrogen molecules to pass through and has effectively blocked the competing reactions, enabling the research team to study the spillover phenomenon. Through various catalyst structure and reactivity analysis, as well as computer modeling, the team has discovered that Brönsted acid sites present on the aluminosilicate plays a crucial role in spillover phenomenon. In addition, the spillover-based hydrogenation catalyst proposed by the research team showed very high hydrogenation and dehydrogenation activity. The ability of the catalyst to significantly inhibit unwanted hydrogenolysis reaction during the petrochemical processes also suggested a large industrial potential. Professor Min-Gi Choi said, “This particular catalyst, which can trigger the reaction only by spillover phenomenon, can be properly designed to exceed the capacity of the conventional metal catalysts. The future goal is to make a catalyst with much higher activity and selectivity.” The research was conducted through funds subsidized by SK Innovation and Ministry of Science, ICT and Future Planning. The senior research fellow of SK Innovation Seung-Hun Oh said, “SK Innovation will continue to develop a new commercial catalyst based on the technology from this research.” Juh-Wan Lim and Hye-Yeong Shin led the research as joint first authors under supervision of Professor Min-Gi Choi and computer modeling works were conducted by KAIST EEWS (environment, energy, water, and sustainability) graduate school’s Professor Hyeong-Jun Kim.
2014.03.03
View 7909
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