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News Article | April 5, 2016
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Professor Wan Kyun Chung of Pohang University of Science and Technology’s Department of Mechanical Engineering — together with PhD student Young Jin Heo, MS student Junsu Kang, and postdoctoral researcher Min Jun Kim in the Robotics Laboratory — has developed a novel control algorithm to resolve critical problems induced from a Proportional-Integral-Derivative (PID) controller by automatizing the technical tuning process. Their research was published in Scientific Reports. “Lab-on-a-chip” designates devices that integrate various biochemical functions on a fingernail-sized chip to enable quick and compact biological analysis or medical diagnosis by processing a small volume of biological samples, such as a drop of blood. To operate various functions on a lab-on-a-chip device, the key technology is the precise and rapid manipulation of fluid on a micro-scale. In microfluidic devices, very small and trivial variables can frequently cause a large amount of errors. Up until now, the PID controller has normally been used for the manipulation of fluids in microfluidic chips. To apply the PID controller, a tedious gain-tuning process is required but the gain-tuning is a difficult process for people who are unfamiliar with control theory. In the case of controlling multiple flows, the process is extremely convoluted and frustrating. The developed control algorithm can improve accuracy and stability of flow regulation in a microfluidic network without requiring any tuning process. With this algorithm, microfluidic flows in multiple channels can be controlled in simultaneous and independent way. The team expects that this algorithm has the potential for many applications of lab-on-a-chip devices. For example, cell culture or biological analysis, which are conducted in biology laboratories, can be performed on a microfluidic chip. Physical and chemical responses can be analyzed in the subdivided levels. This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIP). Source: Pohang University of Science and Technology


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Site: http://phys.org/biology-news/

Majority of human Src homology 2 domains not only bind to proteins, but also interact with membrane lipids with high affinity and specificity. The SH2 domain-containing proteins play important roles in various physiological processes and are involved in cancer development. This study reveals how lipids control SH2 domain-mediated cellular protein interaction networks and suggests a new strategy for the therapeutic modulation of pY-signaling pathways. Prof. You-Me Kim and her student Dajung Jung at Pohang University of Science and Technology (POSTECH), in collaboration with Prof. Wonhwa Cho's group at the University of Illinois at Chicago, have identified that the majority of human Src homology 2 (SH2) domains not only bind to proteins, but also interact with membrane lipids with high affinity and specificity. Their research was published in the online edition of Molecular Cell on March 24th. The SH2 domain interacts with proteins and participates in intracellular signaling by binding to phosphortyrosine (pY) residues of partner proteins. Their mode of interaction with other proteins has been well characterized for a long time. Prof. Kim and her team found that the newly identified lipid binding by the SH2 domain is evolutionarily conserved, suggesting that the interaction serves as an important function for controlling intracellular signal transmission. The SH2 domain-containing proteins play important roles in various physiological processes and are involved in cancer development. This study reveals how lipids control SH2 domain-mediated cellular protein interaction networks and suggests a new strategy for the therapeutic modulation of pY-signaling pathways. Specific inhibitors blocking the SH2 domain-lipid interaction can potentially be developed as an anti-cancer drug. Explore further: Chemists get grip on slippery lipids


Abstract: Polymer semiconductors, which can be processed on large-area and mechanically flexible substrates with low cost, are considered as one of the main components for future plastic electronics. However, they, especially n-type semiconducting polymers, currently lag behind inorganic counterparts in the charge carrier mobility - which characterizes how quickly charge carriers (electron) can move inside a semiconductor - and the chemical stability in ambient air. Recently, a joint research team, consisting of Prof. Kilwon Cho and Dr. Boseok Kang with Pohang University of Science and Technology, and Prof. Yun-Hi Kim and Dr. Ran Kim with Gyungsang National University, has developed a new n-type semiconducting polymer with superior electron mobility and oxidative stability. The research outcome was published in Journal of the American Chemical Society (JACS) as a cover article and highlighted by the editors in JACS Spotlights. The team modified a n-type conjugated polymer with semi-fluoroalkyl side chains - which are found to have several unique properties, such as hydrophobicity, rigidity, thermal stability, chemical and oxidative resistance, and the ability to self-organize. As a result, the modified polymer was shown to form a superstructure composed of polymer backbone crystals and side-chain crystals, resulting in a high degree of semicrystalline order. The team explained this phenomenon is attributed to the strong self-organization of the side chains and significantly boosts charge transport in polymer semiconductors. Prof. Cho emphasized "We investigated the effects of semi-fluoroalkyl side chains of conjugated polymers at the molecular level and suggested a new strategy to design highly-performing polymeric materials for next-generation plastic electronics". This research was supported by the Center for Advanced Soft Electronics under the Global Frontier Research Program and the National Research Foundation (NRF) of Korea funded by the Ministry of Science, ICT and Future Planning. For more information, please click If you have a comment, please us. Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.


News Article
Site: http://phys.org/chemistry-news/

Kilwon Cho and the team's research was published in Journal of the American Chemical Society as a cover article and highlighted by the editors in JACS Spotlights. Credit: Journal of American Chemical Society Polymer semiconductors, which can be processed on large-area and mechanically flexible substrates with low cost, are considered as one of the main components for future plastic electronics. However, they, especially n-type semiconducting polymers, currently lag behind inorganic counterparts in the charge carrier mobility - which characterizes how quickly charge carriers (electron) can move inside a semiconductor - and the chemical stability in ambient air. Recently, a joint research team, consisting of Prof. Kilwon Cho and Dr. Boseok Kang with Pohang University of Science and Technology, and Prof. Yun-Hi Kim and Dr. Ran Kim with Gyungsang National University, has developed a new n-type semiconducting polymer with superior electron mobility and oxidative stability. The research outcome was published in Journal of the American Chemical Society (JACS) as a cover article and highlighted by the editors in JACS Spotlights. The team modified a n-type conjugated polymer with semi-fluoroalkyl side chains - which are found to have several unique properties, such as hydrophobicity, rigidity, thermal stability, chemical and oxidative resistance, and the ability to self-organize. As a result, the modified polymer was shown to form a superstructure composed of polymer backbone crystals and side-chain crystals, resulting in a high degree of semicrystalline order. The team explained this phenomenon is attributed to the strong self-organization of the side chains and significantly boosts charge transport in polymer semiconductors. Prof. Cho emphasized "We investigated the effects of semi-fluoroalkyl side chains of conjugated polymers at the molecular level and suggested a new strategy to design highly-performing polymeric materials for next-generation plastic electronics". This research was supported by the Center for Advanced Soft Electronics under the Global Frontier Research Program and the National Research Foundation (NRF) of Korea funded by the Ministry of Science, ICT and Future Planning.


Home > Press > Spintronics, low-energy electricity take a step closer: A new class of topological insulators discovered Abstract: Topological insulators are materials that let electric current flow across their surface while keeping it from passing it through their bulk. This exotic property makes topological insulators very promising for electricity with less energy loss, spintronics, and perhaps even quantum computing. EPFL scientists have now identified a new class of topological insulators, and have discovered its first representative material, which could propel topological insulators into applications. The work, which was carried out within the framework of the EPFL-led NCCR Marvel project, is published in Nature Materials. The technological promise of topological insulators has led to an intense search for optimal natural and man-made materials with such properties. Such research combines theoretical work that predicts what properties the structure of a particular material would have. The "candidate" materials that are identified with computer simulations are then passed for experimental examination to see if their topological insulating properties match the theoretical predictions. This is what the lab of Oleg Yazyev at EPFL's Institute of Theoretical Physics has accomplished, working with experimentalist colleagues from around the world. By theoretically testing potential candidates from the database of previously described materials, the team has identified a material, described as a "crystalline phase" of bismuth iodide, as the first of a new class of topological insulators. What makes this material particularly exciting is the fact that its atomic structure does not resemble any other topological insulator known to date, which makes its properties very different as well. One clear advantage of bismuth iodide is that its structure is more ordered than that of previously known topological insulators, and with fewer natural defects. In order to have an insulating interior, a material must have as few defects in its structure as possible. "What we want is to pass current across the surface but not the interior," explains Oleg Yazyev. "In theory, this sounds like an easy task, but in practice you'll always have defects. So you need to find a new material with as few of them as possible." The study shows that even these early samples of bismuth iodide appear to be very clean with very small concentration of structural imperfections. After characterizing bismuth iodide with theoretical tools, the scientists tested it experimentally with an array of methods. The main evidence came from a direct experimental technique called "angle-resolved photoemission spectroscopy". This method allows researchers to "see" electronic states on the surface of a solid material, and has become a key technique for proving the topological nature of electronic states at the surface. The measurements, carried out at the Lawrence Berkeley National Lab, proved to be fully consistent with the theoretical predictions made by Gabriel Autès, a postdoc at Yazyev's lab and lead author of the study. The actual electron structure calculations were performed at the Swiss National Supercomputing Centre, while data analysis included a number of scientists from EPFL and other institutions. "This study began as theory and went through the entire chain of experimental verification," says Yazyev. "For us is a very important collaborative effort." His lab is now exploring further the properties of bismuth iodide, as well materials with similar structures. Meanwhile, other labs are joining the effort to support the theory behind the new class of topological insulators and propagate the experimental efforts. ### This study was carried out within the framework of NCCR Marvel, a research effort on Computational Design and Discovery of Novel Materials, created by the Swiss National Science Foundation and led by EPFL. It currently includes 33 labs across 11 Swiss institutions. The work presented here involved a collaboration of EPFL's Institute of Theoretical Physics and Institute of Condensed Matter Physics with TU Dresden; the Lawrence Berkeley National Laboratory; the University of California, Berkeley; Lomonosov Moscow State University; Ulm University; Yonsei University; Pohang University of Science and Technology; and the Institute for Basic Science, Pohang. The study was funded by the Swiss National Science Foundation, the ERC, NCCR-MARVEL, the Deutsche Forschungsgemeinschaft, the U.S. Department of Energy, and the Carl-Zeiss Foundation. Reference Autès G, Isaeva A, Moreschini L, Johannsen JC, Pisoni A, Mori R, Zhang W, Filatova TG, Kuznetsov AN, Forró L, Van den Broek W, Kim Y, Kim KS, Lanzara A, Denlinger JD, Rotenberg E, Bostwick A, Grioni M, Yazyev OV. A Novel Quasi-One-Dimensional Topological Insulator in Bismuth Iodide β-Bi4I4. Nature Materials 14 December 2015. DOI: 10.1038/nmat4488 For more information, please click If you have a comment, please us. Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

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