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Precise control of surface oxygen vacancies in ZnO nanoparticles for extremely high acetone sensing response

Journal of Advanced Ceramics 2022年第5期11卷 769-783页

作者： Jihyun LEE Youngmoon CHOI byoung joon park Jeong Woo HAN Hyun-Sook LEE Jong Hyeok park Wooyoung LEE Department of Materials Science and Engineering Yonsei UniversitySeoul 03722Republic of Korea Department of Chemical and Biological Engineering Yonsei UniversitySeoul 03722Republic of Korea Department of Chemical Engineering Pohang University of Science and TechnologyPohang 37673Republic of Korea Institute for Convergence Research and Education in Advanced Technology Yonsei UniversitySeoul 03722Republic of Korea

ZnO has been studied intensely for chemical sensors due to its high sensitivity and fast ***,we present a simple approach to precisely control oxygen vacancy contents to provide significantly enhanced acetone sensing performance of commercial ZnO nanopowders.A combination of H_(2)O_(2)treatment and thermal annealing produces optimal surface defects with oxygen vacancies on the ZnO nanoparticles(NPs).The highest response of~27,562 was achieved for 10 ppm acetone in 0.125 MH_(2)O_(2)treated/annealed ZnO NPs at the optimal working temperature of 400℃,which is significantly higher than that of reported so far in various acetone sensors based on metal oxide semiconductors(MOSs).Furthermore,first-principles calculations indicate that pre-adsorbed O formed on the surface of H_(2)O_(2)treated ZnO NPs can provide favorable adsorption energy,especially for acetone detection,due to strong bidentate bonding between carbonyl C atom of acetone molecules and pre-adsorbed O on the ZnO *** study demonstrates that controlling surface oxygen vacancies by H_(2)O_(2)treatment and re-annealing at optimal temperature is an effective method to improve the sensing properties of commercial MOS materials.

关键词： gas sensors acetone metal oxide semiconductors(MOSs) ZnO nanoparticles(NPs) H_(2)O_(2)treatment

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Tailoring local structures of atomically dispersed copper sites for highly selective CO_(2) electroreduction

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Carbon Energy 2024年第4期6卷 79-90页

作者： Kyung‐Jong Noh byoung joon park Ying Wang Yejung Choi Sang‐Hoon You Yong‐Tae Kim Kug‐Seung Lee Jeong Woo Han Department of Chemical Engineering Pohang University of Science and Technology(POSTECH)PohangGyeongbukRepublic of Korea Department of Materials Science and Engineering Pohang University of Science and Technology(POSTECH)PohangGyeongbukRepublic of Korea Pohang Accelerator Laboratory(PAL) Beamline DivisionPohangGyeongbukRepublic of Korea

Atomically‐dispersed copper sites coordinated with nitrogen‐doped carbon(Cu–N–C)can provide novel possibilities to enable highly selective and active electrochemical CO_(2) reduction ***,the construction of optimal local electronic structures for nitrogen‐coordinated Cu sites(Cu–N_(4))on carbon remains ***,we synthesized the Cu–N–C catalysts with atomically‐dispersed edge‐hosted Cu–N_(4) sites(Cu–N_(4)C_(8))located in a micropore between two graphitic sheets via a facile method to control the concentration of metal ***‐hosted Cu–N_(4)C_(8) catalysts outperformed the previously reported M–N–C catalysts for CO_(2)‐to‐CO conversion,achieving a maximum CO Faradaic efficiency(FECO)of 96%,a CO current density of–8.97 mA cm^(–2) at–0.8 V versus reversible hydrogen electrode(RHE),and over FECO of 90%from–0.6 to–1.0 V versus *** studies revealed that the micropore of the graphitic layer in edge‐hosted Cu–N_(4)C_(8) sites causes the d‐orbital energy level of the Cu atom to shift upward,which in return decreases the occupancy of antibonding states in the*COOH *** research suggests new insights into tailoring the locally coordinated structure of the electrocatalyst at the atomic scale to achieve highly selective electrocatalytic reactions.

关键词： atomic local structure density functional theory electrochemical CO_(2)reduction metal nitrogen‐doped carbon single‐atom catalyst

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GIGANTEA Shapes the Photoperiodic Rhythms of Thermomorphogenic Growth in Arabidopsis

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Molecular Plant 2020年第3期13卷 459-470页

作者： Young-joon park Jae Young Kim June-Hee Lee byoung-Doo Lee Nam-Chon Paek Chung-Mo park Department of Chemistry Seoul National UniversitySeoul 08826Korea Department of Plant Science Seoul National UniversitySeoul 08826Korea Plant Genomics and Breeding Institute Seoul National UniversitySeoul 08826Korea These authors contributed equally to this article

Plants maintain their internal temperature under environments with fluctuating temperatures by adjusting their morphology and architecture,an adaptive process termed ***,the rhythmic patterns of plant thermomorphogenesis are governed by day-length ***,it remains elusive how thermomorphogenic rhythms are regulated by ***,we show that warm temperatures enhance the accumulation of the chaperone GIGANTEA(Gl),which thermostabilizes the DELLA protein,REPRESSOR OF ga1-3(RGA),under long days,thereby attenuating PHYTOCHROME INTERACTING FACTOR 4(PIF4)-mediated *** contrast,under short days,when Gl accumulation is reduced,RGA is readily degraded through the gibberellic acid-mediated ubiquitination-proteasome pathway,promoting thermomorphogenic *** data indicate that the GI-RGA-PIF4 signaling module enables plant thermomorphogenic responses to occur in a day-length-dependent *** propose that the Gl-mediated integration of photoperiodic and temperature information shapes thermomorphogenic rhythms,which enable plants to adapt to diel fluctuations in day length and temperature during seasonal transitions.

关键词： thermomorphogenesis day length Gl RGA PIF4

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Designing a Biomimetic Ornithopter Capable of Sustained and Controlled Flight

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Journal of Bionic Engineering 2008年第1期5卷 39-47页

作者： joon Hyuk park Kwang-joon Yoon Department of Aerospace Information System and Artificial Muscle Research Center Konkuk University Seoul 143-701 Korea

We describe the design of four ornithopters ranging in wing span from 10 cm to 40 cm, and in weight from 5 g to 45 g. The controllability and power supply are two major considerations, so we compare the efficiency and characteristics between different types of subsystems such as gearbox and tail shape. Our current omithopter is radio-controlled with inbuilt visual sensing and capable of takeoff and landing. We also concentrate on its wing efficiency based on design inspired by a real insect wing and consider that aspects of insect flight such as delayed stall and wake capture are essential at such small size. Most importantly, the advance ratio, controlled either by enlarging the wing beat amplitude or raising the wing beat frequency, is the most significant factor in an ornithopter which mimics an insect.

关键词： biomimetic ornithopter flapping wing unsteady state low Reynolds number

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Thermoresponsive Al^(3+)-crosslinked poly(N-isopropylacrylamide)/alginate composite for green recovery of lithium from Li-spiked seawater

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Green Energy & Environment 2022年第2期7卷 334-344页

作者： Sung Ho park Sang joon Lee Department of Mechanical Engineering Pohang University of Science and Technology(POSTECH)Pohang790-784South Korea

With the rapid increase in the demand for lithium as an energy-critical element,the recovery of Li+ions from seawater is a worldwide challenging ***,we propose a new facile and fast selective recovery approach of Li+using an Al^(3+)-crosslinked poly(N-isopropylacrylamide)(PNIPAAm)/alginate(Alg)(PNP/Alg(Al)) *** in situ TEM images indicate that Alg-Al^(3+)coordination is reorganized via the rearrangement of PNIPAAm and Alg networks,as the temperature *** reorganization eventually leads to the formation of polycrystalline *** in situ FTIR results exhibit that PNP/Alg(Al) composite has peculiar phase transitions,which includes a retrogressive phase change from hydrophobic to *** synergetic effect of the strong repulsion force of Al^(3+) ions and the attractive force of negatively charged polymeric chains enables the efficient adsorption of Li+ions with a low affinity from Li-spiked seawater.7.3% of Li+ions are recovered from Li-spiked seawater although the concentration of Li-spiked seawater is very *** addition,Li+ions can be extracted from PNP/Alg(Al) composite with the use of a small thermal *** proposed thermoresponsive IPN gel provides a strong potential in practical applications for Li+recovery as an innovative energy-material strategy.

关键词： structure seawater lithium

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Environmentally adaptive reshaping of plant photomorphogenesis by karrikin and strigolactone signaling

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Journal of Integrative Plant Biology 2024年第5期66卷 865-882页

作者： Young-joon park Bo Eun Nam Chung-Mo park Department of Smart Farm Science Kyung Hee UniversityYongin 17104Korea Departmentof Biological Sciences Seoul National UniversitySeoul 08826Korea Department of Chemistry Seoul National UniversitySeoul 08826Korea

Coordinated morphogenic adaptation of growing plants is critical for their survival and propagation under fluctuating *** morphogenic responses to light and warm temperatures,termed photomorphogenesis and thermomorphogenesis,respectively,have been extensively studied in recent *** photomorphogenesis,plants actively reshape their growth and developmental patterns to cope with changes in light ***,photomorphogenesis is closely associated with diverse growth hormonal ***,accumulating evidence indicates that light-directed morphogenesis is profoundly affected by two recently identified phytochemicals,karrikins(KARs)and strigolactones(SLs).KARs and SLs are structurally related butenolides acting as signaling molecules during a variety of developmental steps,including seed *** receptors and signaling mediators have been identified,and associated working mechanisms have been explored using gene-deficient mutants in various plant *** particular interest is that the KAR and SL signaling pathways play important roles in environmental responses,among which their linkages with photomorphogenesis are most comprehensively studied during seedling *** this review,we focus on how the phytochemical and light signals converge on the optimization of morphogenic *** also discuss molecular mechanisms underlying the signaling crosstalks with an aim of developing potential ways to improve crop productivity under climate changes.

关键词： karrikins morphogenic adaptation photomorphogenesis seedling establishment strigolactones

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Effect of alkaline metal ions on the photoluminescence properties of Eu^(3+)-doped Ca_3Al_2O_6 phosphors

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Journal of Rare Earths 2016年第12期34卷 1193-1198页

作者： Kyeongsoon park joon Woo Pi Deshmukh Abdul Hakeem Faculty of Nanotechnology and Advanced Materials Engineering Sejong University

Ca3–xAl2O6：x Eu^3＋（0.02≤x≤0.10） and Ca（2.92）Al2O6：0.04Eu^3＋,0.04M^＋（M^＋=Li^＋, Na^＋, and K^＋） phosphors were prepared by sol-gel method and their photoluminescence properties were investigated. The crystal structure of the annealed Ca3–xAl2O6：x Eu^3＋ and Ca（2.92）Al2O6：0.04Eu^3＋,0.04M^＋ phosphors was analyzed with X-ray diffraction（XRD）. The size and morphological characteristics of the annealed phosphors were investigated with a field emission scanning electron microscope（FE-SEM）. The photoluminescence properties were evaluated with a spectrofluorometer. The phosphors were effectively excited by the light of 396 nm and showed intense red emission at 616 nm, which originated from the 5D0→7F2 transition of Eu^3＋. Among the prepared phosphors, the Ca（2.96）Al2O6：0.04Eu^3＋ phosphor showed the strongest emission intensity and the highest color purity. The addition of alkaline metal ions（Li^＋, Na^＋, and K^＋） to Ca（2.96）Al2O6：0.04Eu^3＋ phosphor degraded the emission intensity and color purity.

关键词： phosphor photoluminescence emission sol-gel method Eu3+ rare earths

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Wearable Triboelectric Nanogenerators Based on Printed Polyvinylidene Fluoride Films Incorporated with Cobalt-Based Metal-Organic Framework for Self-Powered Mobile Electronics

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Energy & Environmental Materials 2024年第4期7卷 396-403页

作者： Myeong-Hyeon Kim Sang-joon park Tae-Jun Ha Department of Electronic Materials Engineering Kwangwoon UniversitySeoul 01897Korea

In this study,wearable triboelectric nanogenerators comprising bar-printed polyvinylidene fluoride(PVDF)films incorporated with cobalt-based metal-organic framework(Co-MOF)were *** enhanced output performance of the TENGs was attributed to the phase transition of PVDF from a-crystals toβ-crystals,as facilitated by the incorporation of the *** synthesis conditions,including metal ion,concentration,and particle size of the MOF,were optimized to increase open-circuit voltage(VOC)and open-circuit current(I_(SC))of PVDF-based *** addition to high operational stability,mechanical robustness,and long-term reliability,the developed TENG consisting of PVDF incorporated with Co-MOF(Co-MOF@PVDF)achieved a VOC of 194 V and an I_(SC)of 18.8μ***,the feasibility of self-powered mobile electronics was demonstrated by integrating the developed wearable TENG with rectifier and control units to power a global positioning system(GPS)*** local position of the user in real-time through GPS was displayed on a mobile interface,powered by the battery charged through friction-induced electricity generation.

关键词： bar printing phase transition polyvinylidene fluoride incorporated with cobalt-based metal-organic framework self-powered mobile electronics wearable triboelectric nanogenerators

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Prevalence of coronavirus from diarrheic calves in the Republic of Korea

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Asian Pacific Journal of Tropical Biomedicine 2018年第1期8卷 1-6页

作者： Jinho park Du-Gyeong Han Su Hee Kim Jeong-byoung Chae joon-Seok Chae Do-Hyeon Yu Kyoung-Seong Choi College of Veterinary Medicine Chonbuk National University Department of Animal Science and Biotechnology College of Ecology and Environmental Science Kyungpook National University Animal Disease & Biosecurity Team National Institute of Animal Science Rural Development Administration Laboratory of Veterinary Internal Medicine BK21 PLUS Program for Creative Veterinary Science Research Research Institute for Veterinary Science and College of Veterinary Medicine Seoul National University College of Veterinary Medicine Gyeongsang National University

Objective: To investigate the prevalence of bovine coronavirus(BCo V), bovine rotavirus, and bovine viral diarrhea virus in the feces of normal and diarrheic Korean native calves aged 1-81 days between April and October of 2016 in the Republic of Korea. Methods: Samples were obtained from 50 normal and 93 diarrheic(56 semi-formed, 28 loose, and 9 watery feces) calves in six different regions of northern and southern Korea. These fecal samples were tested for BCo V, bovine rotavirus, and bovine viral diarrhea virus by RT-PCR. Results: Among the three pathogens examined, infection with BCo V was especially prominent in relation to diarrhea among calves aged 1-21 days [odds ratio(OR)=9.3, 95% confidence interval(CI): 1.1-78.9; P=0.02). Infection with BCo V alone(OR=2.9; 95% CI: 1.1-7.6; P=0.03) or coinfection of BCo V with bovine viral diarrhea virus(OR=3.6; 95% CI: 1.0-12.4; P=0.04) was significantly associated with the development of loose feces. Grazing and colostrum intake strongly reduced the occurrence of diarrhea as compared to housed calves(OR=0.2; 95% CI: 0.1-0.4; P=0.00) and calves that had not been fed colostrum(OR=0.2; 95% CI: 0.1-0.7; P=0.02), respectively. Conclusions: The present study suggests that BCo V is involved in calf diarrhea in the Republic of Korea. Therefore, grazing and colostrum intake is recommended for preventing and controlling calf diarrhea caused by BCoV.

关键词： Calf diarrhea Bovine coronavirus Bovine viral diarrhea virus Loose feces Grazing

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Optical enhancement effects of plasmonic nanostructures on organic photovoltaic cells

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Chinese Chemical Letters 2015年第4期26卷 419-425页

作者： Hui joon park L.Jay Guo Division of Energy Systems Research Ajou University Department of Electrical Engineering and Computer Science University of Michigan

In this article, the optical enhancement effects of plasmonic nanostructures on OPV cells were reviewed as an effective way to resolve the mismatch problems between the short exciton diffusion length in organic semiconductors （around 10 nm） and the large thickness required to fully absorb sunlight （e.g. hundreds of nanometers）. Especially, the performances of OPVs with plasmonic nanoparticles in photoactive and buffer layers and with periodic nanostructures were investigated. Furthermore, nanoimprint lithography-based nanofabrication processes that can easily control the dimension and uniformity of structures for large-area and uniform I^lasmonic nanostructures were demonstrated.

关键词： Organic photovoltaicPlasmonic nanostructureNanoparticleNanogratingNanoimprint lithography

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