Utility of RT-PCR-based Dot-blot Hybridization for Detecting and Genotyping Echoviruses

Ahyoun Kim,Wooyoung Choi,Yoonseok Chung,Kisoon Kim,Youngmee Jee,Haewol Cho,Jooshil Lee 대한미생물학회 2007 Journal of Bacteriology and Virology Vol.37 No.3

Blend membranes of polybenzimidazole and an anion exchange ionomer (FAA3) for alkaline water electrolysis: Improved alkaline stability and conductivity

Konovalova, Anastasiia,Kim, Hyemi,Kim, Sangwon,Lim, Ahyoun,Park, Hyun Seo,Kraglund, Mikkel Rykær,Aili, David,Jang, Jong Hyun,Kim, Hyoung-Juhn,Henkensmeier, Dirk Elsevier 2018 Journal of membrane science Vol.564 No.-

<P><B>Abstract</B></P> <P>Anion exchange membranes (AEMs) conduct selectively hydroxide ions, while KOH doped polybenzimidazole is an ion-solvating polymer, conducting both potassium and hydroxide ions. In this work, meta-polybenzimidazole (mPBI) was blended with FAA3, a commercially available AEM, in the ratios of 2:1, 3:1, 4:1, 5:1 and 1:0. Doping was done by immersion in 0, 10, 15, 20, 25 and 30 wt% KOH solutions, giving rise to 30 membranes which were analyzed for their swelling behavior during doping, there composition (polymer, water, KOH), their mechanical properties and their through-plane conductivity in KOH solutions. Especially PF-41 showed higher tensile strength and Young's modulus than mPBI under all tested KOH concentrations. The highest conductivity of 166 mS cm<SUP>−1</SUP> was observed for PF-51 doped in 25% KOH, 80% higher than for mPBI. In an alkaline stability test, blend membranes showed higher tensile strength, Young's modulus and lower weight loss than mPBI after 4 weeks at 85 °C in 25 wt% KOH solution. PF-31 and PF-41 were also tested in an electrolysis cell, where they showed cell resistance comparable to mPBI. Because systems without cathode feed can be quite efficient, the permeability of membranes for KOH solutions was investigated.</P> <P><B>Highlights</B></P> <P> <UL> <LI> PBI and FAA3 were blended and doped with KOH solution. </LI> <LI> Composition (polymer, water, KOH) was analyzed. </LI> <LI> Blends show higher tensile strength and conductivity than PBI. </LI> <LI> Blends show higher alkaline stability (lower weight loss, higher tensile strength). </LI> <LI> In the electrolyzer, performance of the blends was similar to that of PBI. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Electrochemically synthesized nanostructured iron carbide/carbon composite as a low-cost counter electrode for dye-sensitized solar cells

Kim, Jin,Kang, Jin Soo,Jeong, Juwon,Son, Yoon Jun,Lee, Myeong Jae,Kang, Jiho,Lim, Ahyoun,Park, Hyun S.,Sung, Yung-Eun Elsevier 2018 Journal of Power Sources Vol.396 No.-

<P><B>Abstract</B></P> <P>Owing to the rapid increase in global energy consumption, which is currently based on fossil fuel combustion, the importance of renewable energy has become increasingly apparent. Solar energy is one of the most promising candidates to replace conventional energy sources, and various types of photovoltaic devices, including dye-sensitized solar cells, are being intensively investigated as a means for the efficient utilization of sunlight. However, the use of Pt in the counter electrodes of dye-sensitized solar cells limits their economic feasibility for practical and industrial applications. In the present study, to develop an active and economical material to replace Pt in dye-sensitized solar cells, we prepare a nanostructured iron carbide/carbon composite by electrochemical anodization of Fe foil followed by heat treatment in carbon-bearing gas atmosphere, which lead to the formation of conformal carbon shell on the surface of crystalline Fe<SUB>3</SUB>C. The superior catalytic properties of the iron carbide/carbon composite in the cobalt bipyridine redox electrolyte to those of Pt are confirmed by various electrochemical characterization methods. When used as the counter electrode in a dye-sensitized solar cell, the superior properties of the composite provide an 8.0% increase in power conversion efficiency compared to that achieved with a Pt counter electrode.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Nanostructured Fe<SUB>3</SUB>C/C electrode was prepared by a facile electrochemical procedure. </LI> <LI> Fe<SUB>3</SUB>C/C electrode exhibited superior catalytic activities to that of conventional Pt. </LI> <LI> Fe<SUB>3</SUB>C/C electrode in place of Pt counterpart led to an enhanced performance in DSCs. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Micro Flower-Like Hierarchical Mo2C/Co@NC (N-Doped Carbon) for Efficient Bifunctional Electrocatalyst

Kim Hee Soo,Lim Ahyoun,Woo Mino,Lee Hae In,Gu Yunjang,Lim Dong-Ha 한국화학공학회 2024 Korean Journal of Chemical Engineering Vol.41 No.1

The development of low-cost and high-effi ciency electrocatalysts for the water-splitting reaction to produce oxygen and hydrogen from alkaline electrolytes remains a major challenge, especially from the perspective of realizing fast and effi cient oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) catalysts, and it is important to improve the performance of these reactions through rational catalyst design. In this study, Co-based heterostructures composed of cobalt (Co) and molybdenum carbide (Mo 2 C) nanoparticles with micro-fl ower-like structures were intentionally designed as precursors for OER and HER electrocatalysts. In particular, during polymerization, nanoparticle (metal precursor) ions and dopamine aggregates combined to grow into nano-fl akes and retained their structure after carbonization, forming micro-fl ower-like structures characterized by high specifi c surface area and porosity. The catalysts with hierarchical heterostructures constructed using this unique structure showed activities similar to those of the commercially available IrO 2 and Pt/C catalysts, reaching current densities of 10 mA/cm 2 for OER and HER in 0.1 M KOH and exhibiting good durability. Therefore, our results present new concepts for the structuring and fabricating catalysts to realize effi cient OER and HER kinetics, and we expect that they will be utilized in the energy conversion fi eld.

A Review of Industrially Developed Components and Operation Conditions for Anion Exchange Membrane Water Electrolysis

Lim, Ahyoun,Cho, Min Kyung,Lee, So Young,Kim, Hyoung-Juhn,Yoo, Sung Jong,Sung, Yung-Eun,Jang, Jong Hyun,Park, Hyun S. The Korean Electrochemical Society 2017 Journal of electrochemical science and technology Vol.8 No.4

Solid-state alkaline water electrolysis is a promising method for producing hydrogen using renewable energy sources such as wind and solar power. Despite active investigations of component development for anion exchange membrane water electrolysis (AEMWE), understanding of the device performance remains insufficient for the commercialization of AEMWE. The study of assembled AEMWE devices is essential to validate the activity and stability of developed catalysts and electrolyte membranes, as well as the dependence of the performance on the device operating conditions. Herein, we review the development of catalysts and membranes reported by different AEMWE companies such as ACTA S.p.A. and Proton OnSite and device operating conditions that significantly affect the AEMWE performance. For example, $CuCoO_x$ and $LiCoO_2$ have been studied as oxygen evolution catalysts by Acta S.p.A and Proton OnSite, respectively. Anion exchange membranes based on polyethylene and polysulfone are also investigated for use as electrolyte membranes in AEMWE devices. In addition, operation factors, including temperature, electrolyte concentration and acidity, and solution feed methods, are reviewed in terms of their influence on the AEMWE performance. The reaction rate of water splitting generally increases with increase in operating temperature because of the facilitated kinetics and higher ion conductivity. The effect of solution feeding configuration on the AEMWE performance is explained, with a brief discussion on current AEMWE performance and device durability.

A Review on Membranes and Catalysts for Anion Exchange Membrane Water Electrolysis Single Cells

Cho, Min Kyung,Lim, Ahyoun,Lee, So Young,Kim, Hyoung-Juhn,Yoo, Sung Jong,Sung, Yung-Eun,Park, Hyun S.,Jang, Jong Hyun The Korean Electrochemical Society 2017 Journal of electrochemical science and technology Vol.8 No.3

The research efforts directed at advancing water electrolysis technology continue to intensify together with the increasing interest in hydrogen as an alternative source of energy to fossil fuels. Among the various water electrolysis systems reported to date, systems employing a solid polymer electrolyte membrane are known to display both improved safety and efficiency as a result of enhanced separation of products: hydrogen and oxygen. Conducting water electrolysis in an alkaline medium lowers the system cost by allowing non-platinum group metals to be used as catalysts for the complex multi-electron transfer reactions involved in water electrolysis, namely the hydrogen and oxygen evolution reactions (HER and OER, respectively). We briefly review the anion exchange membranes (AEMs) and electrocatalysts developed and applied thus far in alkaline AEM water electrolysis (AEMWE) devices. Testing the developed components in AEMWE cells is a key step in maximizing the device performance since cell performance depends strongly on the structure of the electrodes containing the HER and OER catalysts and the polymer membrane under specific cell operating conditions. In this review, we discuss the properties of reported AEMs that have been used to fabricate membrane-electrode assemblies for AEMWE cells, including membranes based on polysulfone, poly(2,6-dimethyl-p-phylene) oxide, polybenzimidazole, and inorganic composite materials. The activities and stabilities of tertiary metal oxides, metal carbon composites, and ultra-low Pt-loading electrodes toward OER and HER in AEMWE cells are also described.

Enterovirus 71 Infection with Central Nervous System Involvement, South Korea

Ryu, Wi-Sun,Kang, Byunghak,Hong, Jiyoung,Hwang, Seoyeon,Kim, Ahyoun,Kim, Jonghyun,Cheon, Doo-Sung Centers for Disease Control and Prevention 2010 Emerging infectious diseases Vol.16 No.11

<P>We assessed neurologic sequelae associated with an enterovirus 71 (EV71) outbreak in South Korea during 2009. Four of 94 patients had high signal intensities at brainstem or cerebellum on magnetic resonance imaging. Two patients died of cardiopulmonary collapse; 2 had severe neurologic sequelae. Severity and case-fatality rates may differ by EV71 genotype or subgenotype.</P>

Alkaline anion exchange membrane water electrolysis: Effects of electrolyte feed method and electrode binder content

Cho, Min Kyung,Park, Hee-Young,Lee, Hye Jin,Kim, Hyoung-Juhn,Lim, Ahyoun,Henkensmeier, Dirk,Yoo, Sung Jong,Kim, Jin Young,Lee, So Young,Park, Hyun S.,Jang, Jong Hyun Elsevier 2018 Journal of Power Sources Vol.382 No.-

<P><B>Abstract</B></P> <P>Herein, we investigate the effects of catholyte feed method and anode binder content on the characteristics of anion exchange membrane water electrolysis (AEMWE) to construct a high-performance electrolyzer, revealing that the initial AEMWE performance is significantly improved by pre-feeding 0.5 M aqueous KOH to the cathode. The highest long-term activity during repeated voltage cycling is observed for AEMWE operation in the dry cathode mode, for which the best long-term performance among membrane electrode assemblies (MEAs) featuring polytetrafluoroethylene (PTFE) binder–impregnated (5–20 wt%) anodes is detected for a PTFE content of 20 wt%. MEAs with low PTFE content (5 and 9 wt%) demonstrate high initial performance, rapid performance decay, and significant catalyst loss from the electrode during long-term operation, whereas the MEA with 20 wt% PTFE allows stable water electrolysis for over 1600 voltage cycles. Optimization of cell operating conditions (i.e., operation in dry cathode mode at an optimum anode binder content following an initial solution feed) achieves an enhanced water splitting current density (1.07 A cm<SUP>−2</SUP> at 1.8 V) and stable long-term AEMWE performance (0.01% current density reduction per voltage cycle).</P> <P><B>Highlights</B></P> <P> <UL> <LI> Catholyte feed method and anode binder content in an MEA for AEMWE were examined. </LI> <LI> Dry cathode operation was beneficial for long-term performance. </LI> <LI> Optimal PTFE binder content in the anode was 20 wt% for dry cathode operation. </LI> </UL> </P>