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Chinese Journal of Chemistry 2023年第24期41卷 3560-3566页

作者： Vinothkumar Ganesan sungho yoon Department of Chemistry Chung Ang University84 Heukseok-roDongjak-guSeoul06974 Republic of Korea

Poly(3-hydroxyalkanoates) (PHAs) are a promising class of biodegradable polymers,exhibiting properties comparable to traditional petroleum-based ***,the widespread commercialization of PHAs is hindered by the absence of an efficient and economically viable catalytic system,impeding their competitiveness against non-biodegradable *** an effort to address this challenge,we present a study on a newly developed chloro-bridged dimeric salphen zirconium cobaltate complex for the direct synthesis of PHAs via carbonylative polymerization of *** catalytic system demonstrates favorable activity under mild reaction conditions,enabling complete monomer conversion and an impressive 92% selectivity towards PHA *** meticulous control experiments and mechanistic studies,we have gained crucial insights into the polymerization ***,our findings challenge the prevailing notion of sequential ring-opening polymerization of in-situ generated β-lactones as the primary ***,we demonstrate that the polymerization predominantly proceeds through direct co-polymerization of epoxide and carbon monoxide,unveiling a unique and efficient mechanism for PHA synthesis.

关键词： C1 building blocks Chloro bridged salphenZr(IV)dimer Homogeneous catalysis Carbonylation Carbonylative polymerization Biodegradable polymer Poly(3-hydroxyalkanoates)

Development of Air Vehicle with Active Flapping and Twisting of Wing

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Journal of Bionic Engineering 2011年第1期8卷 1-9页

作者： Sangyol yoon Lac-Hyong Kang sungho Jo Department of Computer Science Korea Advanced Institute of Science and Technology Daejeon 305-701 Korea Department of Aerospace Engineering Korea Advanced Institute of Science and Technology Daejeon 305-701 Korea

This paper addresses mechanisms for active flapping and twisting of robotic wings and assesses flying effectiveness as a function of twist angle. Unlike the flapping motion of bird wings, insects generally make a twisting motion at the root of their wings while flapping, which makes it possible for them to hover in midair. This work includes the development of a Voice Coil Motor （VCM） because a flapping-wing air vehicle should be assembled with a compact actuator to decrease size and weight. A linkage mechanism is proposed to transform the linear motion of the VCM into the flapping and twisting motions of wings. The assembled flapping-wing air vehicle, whose weight is 2.86 g, produces an average positive vertical force proportional to the twist angle. The force saturates because the twist angle is mechanically limited. This work demonstrates the possibility of developing a flapping-wing air vehicle that can hover in midair using a mechanism that actively twists the roots of wings during flapping.

关键词： biomimetic flapping-wing air vehicle flapping twisting voice coil motor linkage mechanism

Critical factors to inhibit water-splitting side reaction in carbon-based electrode materials for zinc metal anodes

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Carbon Energy 2022年第6期4卷 1080-1092页

作者： Dong Hyuk Kang Eunji Lee Beom Sik Youn Son Ha Jong Chan Hyun Juhee yoon Dawon Jang Kyoung Sun Kim Hyungsub Kim Sang Moon Lee sungho Lee Hyoung-Joon Jin Hyung-Kyu Lim Young Soo Yun KU-KIST Graduate School of Converging Science and Technology Korea UniversitySeoulSeongbuk-guSouth Korea Division of Chemical Engineering and Bioengineering Kangwon National UniversityChuncheonGangwon-doSouth Korea Department of Eco-Polymer Science and Engineering Inha UniversityIncheonMichuhol-guSouth Korea Carbon Composite Materials Research Center Institute of Advanced Composite MaterialsKorea Institute of Science and Technology(KIST)Jeollabuk-doSouth Korea Department of Chemical and Biological Engineering Korea UniversitySeoulSeongbuk-guSouth Korea Neutron Science Division Korea Atomic Energy Research Institute(KAERI)DaejeonYuseong-guSouth Korea Research Center for Materials Analysis Korea Basic Science Institute(KBSI)DaejeonYuseong-guSouth Korea Department of Integrative Energy Engineering Korea UniversitySeoulSeongbuk-guSouth Korea

Zinc metal anodes(ZMA)have high theoretical capacities(820 mAh g−1 and 5855 mAh cm−3)and redox potential(−0.76 V *** hydrogen electrode),similar to the electrochemical voltage window of the hydrogen evolution reaction(HER)in a mild acidic electrolyte system,facilitating aqueous zinc batteries competitive in next-generation energy storage ***,the HER and byproduct formation effectuated by water-splitting deteriorate the electrochemical performance of ZMA,limiting their *** this study,a key factor in promoting the HER in carbon-based electrode materials(CEMs),which can provide a larger active surface area and guide uniform zinc metal deposition,was investigated using a series of threedimensional structured templating carbon electrodes(3D-TCEs)with different local graphitic orderings,pore structures,and surface *** ultramicropores of CEMs are the determining critical factors in initiating HER and clogging active surfaces by Zn(OH)2 byproduct formation,through a systematic comparative study based on the 3D-TCE series *** the 3D-TCEs had a proper graphitic structure with few ultramicropores,they showed highly stable cycling performances over 2000 cycles with average Coulombic efficiencies of≥99%.These results suggest that a well-designed CEM can lead to high-performance ZMA in aqueous zinc batteries.

关键词： aqueous batteries carbon electrode hydrogen evolution reaction multivalent ion zinc metal anode

Flammable carbon nanotube transistors on a nitrocellulose paper substrate for transient electronics

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Nano Research 2017年第1期10卷 87-96页

作者： Jinsu yoon Juhee Lee Bongsik Choi Dongil Lee Dae Hwan Kim Dong Myong Kim Dong-II Moon Meehyun Lim sungho Kim Sung-Jin Choi School of Electrical Engineering Kookmin University Seou102707 Republic of Korea School of Electrical Engineering Korea Advanced Institute of Science and Technology (KAIST) Daejeon 3414 I Republic of Korea Center for Nanotechnology NASA Ames Research Center Moffett Field CA 94035 USA Test&Package Technology Group Mechatronics R&D Center Samsung Electronics Gyeonggi-do 18448 Repubfic of Korea Department of Electrical Engineering Sejong University Seou105006 Republic of Korea

Transient electronics represent an emerging class of technology comprising materials that can vanish in a controlled manner in response to stimuli. In contrast to conventional electronic devices that are designed to operate over the longest possible period, transient electronics are defined by operation typically over a short and well-defined period; when no longer needed, transient electronics undergo self-deconstruction and disappear completely. In this work, we demonstrate the fabrication of thermally triggered transient electronic devices based on a paper substrate, specifically, a nitrocellulose paper. Nitrocellulose paper is frequently used in acts of magic because it consists of highly flammable components that are formed by nitratil^g cellulose by exposure to nitric acid. Therefore, a complete and rapid destruction of electronic devices fabricated on nitrocellulose paper is possible without producing any residue （i.e., ash）. The transience rates can be modified by controlling radio frequency signal-induced voltages that are applied to a silver （Ag） resistive heater, which is stamped on the backside of the nitrocellulose paper. The Ag resistive heater was prepared by a simple, low-cost stamping fabrication, which requires no harsh chemicals or complex thermal treatments. For the electronics on the nitrocellulose paper substrate, we employed semiconducting carbon nanotube （CNT） network channels in the transistor for superior electrical and mechanical properties.

关键词： carbon nanotube,paper substrate,flammable,transient security