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News Article | February 15, 2017
Site: www.eurekalert.org

A team of researchers, affiliated with UNIST has made a significant breakthrough in the search for the potential root causes of bipolar disorder. The research team, led by Professor Pann-Ghill Suh of Life Sciences at UNIST conducted a study that suggests the cellular protein Phospholipase Cγ1 (PLCγ1) could be a new promising candidate gene for bipolar disorder, also known as manic-depressive illness. The research published by the journal Molecular Psychiatry outlines the findings on January 31, 2017. The findings provide evidence that PLCγ1 is critical for synaptic function and plasticity and that the loss of PLCγ1 from the forebrain results in manic-like behavior. This breakthrough is expected to be widely used in research for the treatment ofthe manic symptoms associated with bipolar disorder. The PLCγ1 has once been proposed as a candidate gene for bipolar disorder in previous studies. However, it has been unclear that how the PLCγ1 plays a role in neron-to-neuron signaling and how it is related to mental illnesses, like bipolar disorder. In the study, Professor Suh and his team created forebrain-specific PLCγ1-deficient mice and observed what happened in the brain synapse of this mouse. Synapse is the part of the neuron where the signal is transmitted from the end. To test whether dysfunction of PLCγ1 in the brain contributes to development of neuropsychiatric disorders, the research team generated mouse models, lacking PLCγ1 in the forebrain and studied the synaptic and neuronal changes in mouse models. The research team reported that mice with forebrain-selective deletion of PLCγ1 also exhibit manic-like behavior, as well as deficits in inhibitory transmission and BDNF-dependent synaptic plasticity. This resulted in the imbalance between excitatory and inhibitory synaptic transmission in forebrain circuits, leading to behavioral abnormalities and manic episodes of bipolar disorder. These symptoms were alleviated after the drug treatment for bipolar disorder was given. "In the brain, excitatory synapses and inhibitory synapses work together to remain balanced for proper neurotransmission," says Professor Suh. "Our study demonstrated that the imbalance between these two is a major cause of various neuropsychiatric disorders and the GABAergic dysfunction observed in the hippocampi of bipolar disorder patients." According to the research team, the inhibitory synapses that lacks PLCγ1 protein do not work properly in excitatory neurons. This is due to the improper signaling of BDNF, which is critical for the synapse formation. This leads to an imbalance of excitatory synapses and inhibitory synapses, and causes mental illnesses, like bipolar disorder. "After 10 years of research, we have finally revealed PLCγ1 protein plays a major role in the onset of bipolar disorder," says Professor Suh. "Our findings, therefore, provide evidence that PLCγ1 is critical for synaptic function and plasticity and that the loss of PLCγ1 from the forebrain results in manic-like behavior." The research was carried out with the support of the future creation science department and the Korea Research Foundation. Y R Yang, et al.,"Forebrain-specific ablation of phospholipase Cγ1 causes manic-like behavior," Molecular Psychiatry, (2017).


News Article | February 15, 2017
Site: www.eurekalert.org

Their findings published in the recent issue of the journal Nature Nanotechnology. UNIST scientists have developed an exiting new catalyst that can split water into hydrogen almost as good as platinum, but less costly and found frequently on Earth. As described in the journal Nature Nanotechnology, this ruthenium (Ru)-based material works almost as efficient as platinum and likely shows the highest catalytic performance without being affected by the pH of the water. The research team, led by Professor Jong-Beom Baek of the Energy and Chemical Engineering at UNIST has synthesized Ru and C?N, a two-dimensional organic structure, to verify its performance as a water-splitting catalyst. With the aid of this new catalyst, entitled Ru@C?N it is now possible to efficiently produce hydrogen. The technology for producing hydrogen from water requires a good catalyst for commercial competitiveness. These water-splitting catalysts must exhibit high hydrogen conversion efficiency and excellent durability, operate well under low-voltage, and should be economical. The Pt-based catalysts used in the hydrogen generation reaction are highly expensive noble metals, resulting in additional costs and difficulty of mass production. They are also less stable in an alkaline environment. One solution, many researchers suggest, was to build catalysts made of cheap, non-noble metals. However, because these materials corrode rapidly under acidic condition and operate at very-high voltages, productivity was limited. The Ru@C?N, developed by Professor Baek is a high-performance material that satisfies all four commercial competitiveness of water-splitting catalysts. This material exhibits high turnover frequency (TOF) as high as Pt and can be operated on low-voltage supply. In addition, it is not affected by the pH of the water and can be used in any environment. The synthesis process of Ru@C?N is simple. Professor Baek and his colleagues simply mixed the ruthenium salt (RuCl?) with the monomers which forms the porous two-dimensional organic structure, C?N. The Ru@C?N catalyst is then produced after going through reduction and heat treatment processes. The researchers used the same process to build M@C?N (M = Co, Ni, Pd, Pt) catalysts, using cobalt (Co), nickel (Ni), lead (Pb) and platinum (Pt). When comparing their efficiency of hydrogen production, the Ru@C?N catalyst exhibited the highest catalytic performance at the lowest overvoltage, as well as superior catalytic activity. "Our study not only suggests new directions in materials science, but also presents a wide range of possibilities from basic to applied science," says Professor Baek. "This material is expected to attract attention in many areas thanks to its scientific potential." This study has been jointly conducted by postdoctoral researchers, Javeed Mahmood and Feng Li of Energy and Chemical Engineering at UNIST. Professor Jong-Beom Baek, Professor Hu Young Jeong of UCRF, and Professor Noejung Park of Natural Science partook as corresponding authors of this study. The research was supported by the Leader Researcher Support Project (Creative Research) by the Ministry of Science, ICT and Future Planning (MSIP) and the BK 21 Plus Project by the Ministry of Education (MOE) and the National Research Foundation of Korea (NRF). Javeed Mahmood et al., "An Efficient and pH-universal ruthenium-based catalyst for hydrogen evolution reaction," Nature Nanotechnology, (2017).


News Article | February 15, 2017
Site: www.eurekalert.org

Eleven UNIST students have been recognized for their excellence in academic and research work at the 23rd Annual International Samsung Human-Tech Paper Awards, held on February 7, 2017. Established in 1994, this competition recognizes an elite cadre of creative young researchers who through competition have demonstrated excellence in research. Approximately 1,500 papers are submitted each year, yet only a small percentage of papers are selected for the prestigious prize. Among the many eminent individuals, the following students won prestige for their latest research in their respective fields, listed below. Narendra Chaudhary, a PhD student of Life Sciences at UNIST, is one of the only two international students in South Korea to receive the award. He is currently developing visualization techniques for arrangement and interactions of specific gene loci in living cells. "It is a great honor to be given this exceptional award," says Narendra. "Through direct observation of the 3D structural changes in the human genome, I would like to provide new perspectives on existing genomic research." "Nothing is more rewarding to me as a teacher than seeing my students succeed," says Professor Hajin Kim. "Chaudhary is a dilligent student, capable of conducting research on the topic of self-selection and I am very proud of him." The award ceremony for the 2017 Samsung HumanTech Paper Awards took place in the fifth floor meeting room of Samsung Electronics, Seocho Discrict, Seoul on February 7, 2017. In this year, out of 1,500 excellent papers considered from high schools and universities, only 116 papers (79 from universities and 27 from highschools) were selected to receive the awards.


News Article | February 15, 2017
Site: www.treehugger.com

There have been so many new approaches to batteries lately that it's hard to keep track of them all, but most of them have one thing in common: they are all cheaper and safer than lithium-ion batteries. Listen, lithium-ion batteries are the best we've got on the market right now. They can store a lot of energy in a small, lightweight package -- that's why they're in basically everything we own -- but they also have some drawbacks. The materials needed to make them aren't earth-abundant, which makes them more expensive, especially as you scale up in size. They are a fire risk and they also have a fairly short life span. For years, researchers have been looking to more abundant, safer materials to create a better battery. Engineers at South Korea's Ulsan National Institute of Science and Technology (UNIST) are just the latest. They have developed a seawater battery that runs on water and salt, which they say could soon rival the lithium-ion battery in performance. Sodium is the sixth most abundant element on earth, making this battery far cheaper to manufacture and using seawater specifically greatly reduces any chance of fire. The researchers believe that in the future, seawater could be the key to the large-scale energy storage that's needed as the world shifts to more renewable energy. The batteries could also be used as emergency back-up energy for homes, businesses and ships. The seawater battery works much like a lithium-ion battery as the structure is the same, swapping out lithium for sodium. The university explains: The salt water is not just acting as an electrolyte; according to the American Chemical Society newsletter it is actually a "catholyte — an electrolyte and cathode combined. In batteries, the electrolyte is the component that allows an electrical charge to flow between the cathode and anode. A constant flow of seawater into and out of the battery provides the sodium ions and water responsible for producing a charge." Currently, the seawater batteries have a lower electrical output than lithium-ion batteries, but the researchers are working on building the batteries in various sizes and shapes to increase the charge rate. They will soon start mass producing the seawater batteries in a testing facility and join cells together in battery packs. The goal is to produce a battery pack by the end of next year that is capable of providing the home energy needs of a family of four.


News Article | February 28, 2017
Site: www.eurekalert.org

Alzheimer's disease (AD) is one of the most common form of dementia. In search for new drugs for AD, the research team, led by Professor Mi Hee Lim of Natural Science at UNIST has developed a metal-based substance that works like a pair of genetic scissors to cut out amyloid-β (Aβ), the hallmark protein of AD. The study has been featured on the cover of the January 2017 issue of the Journal of the American Chemical Society (JACS) and has been also selected as a JACS Spotlight article. Alzheimer's disease is the sixth leading cause of death among in older adults. The exact causes of Alzheimer's disease are still unknown, but several factors are presumed to be causative agents. Among these, the aggregation of amyloid-β peptide (Aβ) has been implicated as a contributor to the formation of neuritic plaques, which are pathological hallmarks of Alzheimer's disease (AD). As therapeutics for AD, Professor Lim suggested a strategy that uses matal-based complexes for reducing the toxicity of the amyloid beta (Aβ). Althought various metal complexs have been suggested as therapeutics for AD, none of them work effectively in vivo. The research team has found that they can hydrolyze amyloid-beta proteins using a crystal structure, called tetra-N methylated cyclam (TMC). Hydrolysis is the process that uses water molecules to split other molecules apart. The metal-mediated TMC structure uses the external water and cut off the binding of amyloid-beta protein effectively. In this study, the following four metals (cobalt, nickel, copper and zinc) were placed at the center of the TMC structure. When the double-layered cobalt was added to the center, the hydrolysis activity was at the highest. The research team reported that the cobalt-based metal complex (Co(II)(TMC)) had the potential to penetrate the blood brain barrier and the hydrolysis activity for nonamyloid protein was low. Moreover, the effects of this substance on the toxicity of amyloid-beta protein were also observed in living cell experiments. "This material has a high therapeutic potential in the treatment of Alzheimer's disease as it can penetrate the brain-vascular barrier and directly interact with the amyloid-beta protein in the brain," says Professor Lim. This study has also attracted attention by the editor of the Journal of the American Chemical Society. "Not only do they develop new materials, but they have been able to propose details of the working principles and experiments that support them," according to the editor. "As a scientist, this is such a great honor to know that our recent publication in JACS was highlighted in JACS Spotlights," says Professor Lim. "This means that our research has not only been recognized as an important research, but also has caused a stir in academia." This study has been conducted in collaboration with Professor Jaeheung Cho of Daegu Gyeongbuk Institute of Science and Technology (DGIST), Professor Kiyoung Park of Korea Advanced Institute of Science and Technology (KAIST), and Dr. Sun Hee Kim of Korea Basic Science Institute (KBSI). It has been also supporte by the National Research Foundation of Korea (NRF) and the Ministry of Science, ICT and Future Planning (MSIP). Jeffrey S. Derrick et al., "Mechanistic Insights into Tunable Metal-Mediated Hydrolysis of Amyloid-β Peptides", JACS, (2017).


Kim J.-Y.,UNIST | Jang D.,California Institute of Technology | Greer J.R.,California Institute of Technology
Advanced Functional Materials | Year: 2011

Homogeneous plasticity in metallic glasses is generally only observed at high temperatures or in very small structures (less than ≈100 nm), so their applications for structural performance have been very limited. Here, nanolaminates with alternating layers of Cu50Zr50 metallic glass and nanocrystalline Cu are synthesized and it is found that samples with an optimal composition of 112-nm-thick metallic-glass layers and 16-nm-thick Cu layers demonstrate a maximum strength of 2.513 GPa, a value 33% greater than that predicted by the rule-of-mixtures and 25% better than that of pure Cu 50Zr50 metallic glass. Furthermore, ≈4% strain at fracture is achieved, suppressing the instantaneous catastrophic failure often associated with metallic glasses. It is postulated that this favorable combination of high strength and deformability is caused by the size-dependent deformation-mode transition in metallic glasses, from highly localized plasticity, leading to immediate failure in larger samples to homogeneous extension in the smaller ones. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Hessari P.,UNIST
Computers and Mathematics with Applications | Year: 2014

The first order system least squares method for the Stokes equation with discontinuous viscosity and singular force along the interface is proposed and analyzed. First, interface conditions are derived. By introducing a physical meaningful variable such as the velocity gradient, the Stokes equation transformed into a first order system of equations. Then the continuous and discrete norm least squares functionals using Legendre and Chebyshev weights for the first order system are defined. We showed that continuous and discrete homogeneous least squares functionals are equivalent to appropriate product norms. The spectral convergence of the proposed method is given. A numerical example is provided to support the method and its analysis. © 2014 Elsevier Ltd. All rights reserved.


News Article | February 15, 2017
Site: phys.org

This new ultra-thin oxide semiconductors was created by a team of scientists, led by Professor Zonghoon Lee of Materials Science and Engineering at UNIST. In the study, Professor Lee has succeeded in demonstrating the formation of two-dimensional zinc oxide (ZnO) semiconductor with one atom thickness. This material is formed by directly growing a single-atom-thick ZnO layer on graphene, using atomic layer deposition. It is also the thinnest heteroepitaxial layer of semiconducting oxide on monolayer graphene. "Flexible, high-performance devices are indispensable for conventional wearable electronics, which have been attracting attention recently," says Professor Lee. "With this new material, we can achieve truly high-performance flexible devices." Semiconductor technology continually moves toward smaller feature sizes and greater operational efficiency and the existing silicon semiconductors seem to also follow this trend. However, as the fabrication process becomes finer, the performance becomes much critical issue and there has been much research on next-generation semiconductors, which can replace silicon. Graphene has superior conductivity properties, but it cannot be directly used as an alternative to silicon in semiconductor electronics because it has no band gap. A bandgap gives a material the ability to start and stop the flow of electrons that carry electricity. In graphene, however, electrons move randomly at a constant speed no matter their energy and they cannot be stopped. To solve this, the research team decided to demonstrate atom-by-atom growth of zinc and oxygen at the preferential zigzag edge of a ZnO monolayer on graphene through in situ observation. Then, they experimentally determine that the thinnest ZnO monolayer has a wide band gap (up to 4.0 eV), due to quantum confinement and graphene-like 'hyper-honeycomb' structure, and high optical transparency. The currently-existing oxide semiconductors have a relatively large bandgap in the range of 2.9-3.5 eV. The greater the band gap energy, the lower the leakage current and excess noise. "This is the first time to actually observe the in situ formation of hexagonal structure of ZnO," says Hyo-Ki Hong of Materials Science and Engineering, first author of the paper. "Through this process, we could understand the process and principle of 2D ZnO semiconductor productiom." "The heteroepitaxial stack of the thinnest 2D oxide semiconductors on graphene has potential for future optoelectronic device applications associated with high optical transparency and flexibility," says Professor Lee. "This study can lead to a new class of 2D heterostructures including semiconducting oxides formed by highly controlled epitaxial growth through a deposition route." Explore further: Model accurately predicts the electronic properties of a combination of 2-D semiconductors More information: Hyo-Ki Hong et al, Atomic Scale Study on Growth and Heteroepitaxy of ZnO Monolayer on Graphene, Nano Letters (2017). DOI: 10.1021/acs.nanolett.6b03621


News Article | February 15, 2017
Site: phys.org

Shown above is the Internal Photoemission (IPE) Measurement System, developed by Hoon Hahn Yoon, combined M.S./Ph.D. student of Natural Science at UNIST. Credit: UNIST A team of researchers affiliated with UNIST has created a new technique that greatly enhances the performance of Schottky diodes used in electronic devices. Their research findings have attracted considerable attention within the scientific community by solving the contact resistance problem of metal semiconductors, which had remained unsolved for almost 50 years. As described in the January issue of Nano Letters, the researchers have created a new type of diode with a graphene insertion layer sandwiched between metal and semiconductor. This new technique supplants previous attempts, and is expected to significantly contribute to the semiconductor industry's growth. The Schottky diode is one of the oldest semiconductor devices, formed by the junction of a semiconductor with a metal. However, due to the atomic intermixing along the interface between two materials, it is impossible to produce an ideal diode. Professor Kibog Park solved this problem by inserting a graphene layer at the metal-semiconductor interface. In the study, the research team demonstrated that this graphene layer, consisting of a single layer of carbon atoms, not only suppresses the material intermixing substantially, but also matches well with the theoretical prediction. "The sheets of graphene in graphite have a space between each sheet that shows a high electron density of quantum mechanics, in that no atoms can pass through," says Professor Park. "Therefore, with this single-layer graphene sandwiched between the metal and semiconductor, it is possible to overcome the inevitable atomic diffusion problem." According to Hoon Hahn Yoon, the first author, the study also confirms the prediction that "in the case of silicon semiconductors, the electrical properties of the junction surfaces hardly change regardless of the type of metal they use." The internal photoemission method was used to measure the electronic energy barrier of the newly fabricated metal/graphene/n-Si(001) junction diodes. The internal photoemission (IPE) measurement system in the image shown above has contributed greatly to these experiments. Explore further: New theory establishes a path to high-performance 2D semiconductor devices More information: Hoon Hahn Yoon et al, Strong Fermi-Level Pinning at Metal/n-Si(001) Interface Ensured by Forming an Intact Schottky Contact with a Graphene Insertion Layer, Nano Letters (2017). DOI: 10.1021/acs.nanolett.6b03137


News Article | February 15, 2017
Site: phys.org

As described in the journal Nature Nanotechnology, this ruthenium (Ru)-based material works almost as efficient as platinum and likely shows the highest catalytic performance without being affected by the pH of the water. The research team, led by Professor Jong-Beom Baek of the Energy and Chemical Engineering at UNIST has synthesized Ru and C2N, a two-dimensional organic structure, to verify its performance as a water-splitting catalyst. With the aid of this new catalyst, entitled Ru@C2N it is now possible to efficiently produce hydrogen. The technology for producing hydrogen from water requires a good catalyst for commercial competitiveness. These water-splitting catalysts must exhibit high hydrogen conversion efficiency and excellent durability, operate well under low-voltage, and should be economical. The Pt-based catalysts used in the hydrogen generation reaction are highly expensive noble metals, resulting in additional costs and difficulty of mass production. They are also less stable in an alkaline environment. One solution, many researchers suggest, was to build catalysts made of cheap, non-noble metals. However, because these materials corrode rapidly under acidic condition and operate at very-high voltages, productivity was limited. The Ru@C?N, developed by Professor Baek is a high-performance material that satisfies all four commercial competitiveness of water-splitting catalysts. This material exhibits high turnover frequency (TOF) as high as Pt and can be operated on low-voltage supply. In addition, it is not affected by the pH of the water and can be used in any environment. The synthesis process of Ru@C2N is simple. Professor Baek and his colleagues simply mixed the ruthenium salt (RuCl3) with the monomers which forms the porous two-dimensional organic structure, C2N. The Ru@C2N catalyst is then produced after going through reduction and heat treatment processes. The researchers used the same process to build M@C?N (M = Co, Ni, Pd, Pt) catalysts, using cobalt (Co), nickel (Ni), lead (Pb) and platinum (Pt). When comparing their efficiency of hydrogen production, the Ru@C2N catalyst exhibited the highest catalytic performance at the lowest overvoltage, as well as superior catalytic activity. "Our study not only suggests new directions in materials science, but also presents a wide range of possibilities from basic to applied science," says Professor Baek. "This material is expected to attract attention in many areas thanks to its scientific potential." Explore further: New approach to water splitting could improve hydrogen production More information: Javeed Mahmood et al, An efficient and pH-universal ruthenium-based catalyst for the hydrogen evolution reaction, Nature Nanotechnology (2017). DOI: 10.1038/nnano.2016.304

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