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Oxygen vacancy engineering for tuning the catalytic activity of LaCoO_(3) perovskite

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Journal of Rare Earths 2024年第3期42卷 506-514,I0003页

作者： Jeong hyun Cho Minjae Kim Inchan Yang Kyung tae park Chang Houn Rhee Hai Woong park Ji Chul Jung Department of Chemical Engineering Myongji UniversityYongin 17058Republic of Korea Institute of Advanced Composite Materials Korea Institute of Science and TechnologyWanju-gunJeollabuk-do 55324Republic of Korea Iron&Steel Process Engineering Research Group POSCOPohang 37859Republic of Korea Hydrogen Research Center Research Institute of Industrial Science&Technology(RIST)Pohang 37673Republic of Korea

Herein, we attempted to engineer oxygen vacancies on the surface of LaCoO_(3) perovskite through simple post-treatments(acid or reductive thermal treatments). Acid treatment induces oxygen vacancies through the selective etching of the La cations, whereas thermal treatment in a reducing atmosphere generates oxygen vacancies by directly removing lattice oxygen. The characterization results confirm that the number of surface oxygen vacancies, which are crucial in various catalytic oxidation reactions,considerably increases in the LaCoO_(3) catalysts treated with acid or reducing gas. Acid treatment enriches the oxygen vacancies while maintaining the structure of the LaCoO_(3) catalysts, which can not be achieved through reductive thermal treatment. Therefore, the acid treatment is considered a promising technique for oxygen vacancy engineering of perovskite catalysts for tuning their catalytic activities. Furthermore,the catalytic activities of the posttreated LaCoO_(3) catalysts for CO oxidation were evaluated and are noted to be considerably better than those of the pristine LaCoO_(3) catalyst due to their abundant oxygen vacancies. Consequently, we conclude that the oxygen vacancies of perovskite catalysts can be effectively engineered via two simple methods and play a significant role in CO oxidation.

关键词： LaCoO_(3)perovskite Acid treatment Reductive thermal treatment Oxygen vacancy CO oxidation Rare earths

Polymer waveguide tunable transceiver for photonic front-end in the 5G wireless network

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Photonics Research 2021年第2期9卷 181-186页

作者： tae-hyun park SUNG-MOON KIM EUN-SU LEE MIN-CHEOL OH Department of Electronics Engineering Pusan National UniversityPusan(Busan)46241Republic of Korea

A photonic front-end in the 5 G wireless network based on wavelength-division multiplexing optical communication requires low-cost tunable transceivers. By exploiting polymer waveguide Bragg-grating technology, we propose a tunable transceiver consisting of an external cavity tunable laser and a tilted grating tunable *** particular, a double-reflection tunable filter provides narrower reflection bandwidth and suppresses undesired mode coupling, improving the side-mode suppression ratio(SMSR) and reducing adjacent-channel crosstalk. By introducing perfluorinated polymers with low birefringence, polarization independence, which is a prerequisite for wavelength filter elements, is secured, and 20 d B bandwidth of 0.69 nm, wavelength tunability over 40 nm,and SMSR of 42 d B are achieved.

关键词： tunable waveguide network

M1-polarized macrophage-derived cellular nanovesicle-coated lipid nanoparticles for enhanced cancer treatment through hybridization of gene therapy and cancer immunotherapy

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Acta Pharmaceutica Sinica B 2024年第7期14卷 3169-3183页

作者： Ha Eun Shin Jun-Hyeok Han Seungyong Shin Ga-hyun Bae Boram Son tae-hyung Kim Hee Ho park Chun Gwon park Wooram park Department of Integrative Biotechnology Sungkyunkwan University(SKKU)SuwonGyeonggi 16419Republic of Korea Deparment of Inteligent Precision Healthcare Convergence SKKUSuwonGyeonggi 16419Republic of Korea Department of MetaBioHealth SKKU Institute for ConvergenceSKKUSuwonGyeonggi 16419Republic of Korea Department of Bioengineering Hanyang UniversitySeoul 04763Republic of Korea Department of Integrative Engineering Chung-Ang UniversitySeoul 06974Republic of Korea Department of Biomedical Engineering SKKUSuwonGyeonggi 16419Republic of Korea Korea Institute of Science and Technology(KIST) Seoul 02792Republic of Korea

Optimum genetic delivery for modulating target genes to diseased tissue is a major obstacle for profitable gene *** nanoparticles(LNPs),considered a prospective vehicle for nucleic acid delivery,have demonstrated efficacy in human use during the COVID-19 *** study introduces a novel biomaterial-based platform,M1-polarized macrophage-derived cellular nanovesicle-coated LNPs(M1-C-LNPs),specifically engineered for a combined gene-immunotherapy approach against solid *** dual-function system of M1-C-LNPs encapsulates Bcl2-targeting siRNA within LNPs and immune-modulating cytokines within M1 macrophage-derived cellular nanovesicles(M1-NVs),effectively facilitating apoptosis in cancer cells without impacting T and NK cells,which activate the intratumoral immune response to promote granule-mediating killing for solid tumor *** retention within tumor was observed upon intratumoral administration of M1-C-LNPs,owing to the presence of adhesion molecules on M1-NVs,thereby contributing to superior tumor growth *** findings represent a promising strategy for the development of targeted and effective nanoparticle-based cancer genetic-immunotherapy,with significant implications for advancing biomaterial use in cancer therapeutics.

关键词： Genetic-immunotherapy M1 macrophage-derived cellular nanovesicles Lipid nanoparticles(LNPs) Gene therapy siRNA Cancer immunotherapy Solid tumor Tumor microenvironment(TME)

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 University

In this study,wearable triboelectric nanogenerators comprising bar-printed polyvinylidene fluoride (PVDF) films incorporated with cobalt-based metalorganic framework (Co-MOF) were *** enhanced output performance of the TENCs was attributed to the phase transition of PVDF from α-crystals to β-crystals,as facilitated by the incorporation of the MOF.

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

Effect of hafnium and molybdenum addition on inclusion characteristics in Co-based dual-phase high-entropy alloys

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International Journal of Minerals,Metallurgy and Materials 2024年第7期31卷 1639-1650页

作者： Yong Wang Wei Wang Joo hyun park Wangzhong Mu Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education&Hubei Provincial Key Laboratory for New Processes of Ironmaking and Steelmaking Wuhan University of Science and TechnologyWuhan 430081China Department of Materials Science and Engineering KTH Royal Institute of TechnologySE-10044StockholmSweden Department of Chemical Engineering Northeast Electric Power UniversityJilin 132012China Department of Materials Science and Chemical Engineering Hanyang UniversityAnsan 15588Korea Engineering Materials Division of Materials ScienceDepartment of Engineering Science and MathematicsLuleå University of Technology97187 LuleåSweden

Specific grades of high-entropy alloys(HEAs)can provide opportunities for optimizing properties toward high-temperature *** this work,the Co-based HEA with a chemical composition of Co_(47.5)Cr_(30)Fe_(7.5)Mn_(7.5)Ni_(7.5)(at%)was *** refractory metallic elements hafnium(Hf)and molybdenum(Mo)were added in small amounts(1.5at%)because of their well-known positive effects on high-temperature *** characteristics were comprehensively explored by using a two-dimensional cross-sectional method and extracted by using a three-dimensional electrolytic extraction *** results revealed that the addition of Hf can reduce Al_(2)O_(3)inclusions and lead to the formation of more stable Hf-rich inclusions as the main *** addition cannot influence the inclusion type but could influence the inclusion characteristics by affecting the physical parameters of the HEA *** calculated coagulation coefficient and collision rate of Al_(2)O_(3)inclusions were higher than those of HfO_(2)inclusions,but the inclusion amount played a larger role in the agglomeration behavior of HfO_(2)and Al_(2)O_(3)*** impurity level and active elements in HEAs were the crucial factors affecting inclusion formation.

关键词： high-entropy alloy non-metallic inclusion agglomeration thermodynamics alloying

Depolarization mitigated in ferroelectric Hf_(0.5)Zr_(0.5)O_(2)ultrathin films(<5 nm)on Si substrate by interface engineering

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Journal of Advanced Ceramics 2024年第3期13卷 282-292页

作者： Se hyun Kim Younghwan Lee Dong hyun Lee Geun Hyeong park hyun Woo Jeong Kun Yang Yong Hyeon Cho Young Yong Kim Min Hyuk park Department of Materials Science and Engineering College of EngineeringSeoul National UniversitySeoul 08826Republic of Korea Research Institute of Advanced Materials College of EngineeringSeoul National UniversitySeoul 08826Republic of Korea Inter-university Semiconductor Research Center College of EngineeringSeoul National UniversitySeoul 08826Republic of Korea Pohang Accelerator Laboratory Pohang University of Science&TechnologyPohang 790784Republic of Korea

(Hf,Zr)O_(2)offers considerable potential for next-generation semiconductor devices owing to its nonvolatile spontaneous polarization at the ***,scaling this material to sub-5 nm thickness poses several challenges,including the formation of an interfacial layer and high trap *** particular,a low-k SiO_(2)interfacial layer is naturally formed when(Hf,Zr)O_(2)films are directly grown on a Si substrate,leading to high depolarization fields and rapid reduction of the remanent *** address these issues,we conducted a study to significantly improve ferroelectricity and switching endurance of(Hf,Zr)O_(2)films with sub-5 nm thicknesses by inserting a TiO_(2)interfacial *** deposition of a Ti film prior to Hf_(0.5)Zr_(0.5)O_(2)film deposition resulted in a high-k TiO_(2)interfacial layer and prevented the direct contact of Hf_(0.5)Zr_(0.5)O_(2)with *** findings show that the high-k TiO_(2)interfacial layer can reduce the SiO_(2)/Si interface trap density and the depolarization field,resulting in a switchable polarization of 60.2μC/cm^(2)for a 5 nm thick Hf_(0.5)Zr_(0.5)O_(2)***,we propose that inserting a high-k TiO_(2)interfacial layer between the Hf_(0.5)Zr_(0.5)O_(2)film and the Si substrate may offer a promising solution to enhancing the ferroelectricity and reliability of(Hf,Zr)O_(2)grown on the Si substrate and can pave the way for next-generation semiconductor devices with improved performance.

关键词： ferroelectric charge trapping hafnia depolarization

Electrochemically Deposited CZTSSe Thin Films for Monolithic Perovskite Tandem Solar Cells with Efficiencies Over 17%

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Energy & Environmental Materials 2024年第1期7卷 147-152页

作者： Sun Kyung Hwang Ik Jae park Se Won Seo Jae hyun park So Jeong park Jin Young Kim Department of Materials Science and Engineering Seoul National UniversitySeoul 08826Korea Department of Applied Physics Sookmyung Women's UniversitySeoul 04310Korea Research Institute of Advanced Materials and Systems Sookmyung Women's UniversitySeoul 04310Korea Research Institute of Advanced Materials(RIAM) Seoul National UniversitySeoul 08826Korea

In spite of the high potential economic feasibility of the tandem solar cells consisting of the halide perovskite and the kesterite Cu2ZnSn(S,Se)4(CZTSSe),they have rarely been demonstrated due to the difficulty in implementing solution-processed perovskite top cell on the rough surface of the bottom ***,we firstly demonstrate an efficient monolithic two-terminal perovskite/CZTSSe tandem solar cell by significantly reducing the surface roughness of the electrochemically deposited CZTSSe bottom *** surface roughness(R_(rms))of the CZTSSe thin film could be reduced from 424 to 86 nm by using the potentiostatic mode rather than using the conventional galvanostatic mode,which can be further reduced to 22 nm after the subsequent ion-milling *** perovskite top cell with a bandgap of 1.65 eV could be prepared using a solution process on the flattened CZTSSe bottom cell,resulting in the efficient perovskite/CZTSSe tandem solar *** the current matching between two subcells involving the thickness control of the perovskite layer,the best performing tandem device exhibited a high conversion efficiency of 17.5%without the hysteresis effect.

关键词： CZTSSe monolithic tandem solar cells perovskite solution process surface roughness control

Extracellular vesicles for neural regeneration after spinal cord injury

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Neural Regeneration Research 2024年第3期19卷 491-492页

作者： Young-Ju Lim Wook-tae park Gun Woo Lee Department of Orthopedic Surgery Yeungnam University Medical CenterYeungnam University College of MedicineDaeguKorea

What is spinal cord injury:Spinal cord injury(SCI)is the damage to the structure of the bundles of cells and nerves that communicate signals from the brain to the body and *** pathology of SCI includes both primary and secondary injuries(Morales et al.,2016).Physical forces such as compression,shearing,contusion,and tearing are major causes of primary injury in *** are two main processes in primary injury:acute and *** acute phase includes traumatic disruption of axons and hemorrhage of the blood vessels around the spinal *** injury to the vessels can lead to increased edema within the neural and cord tissues,susceptibility to infiltration by microglia and astrocytes,excitotoxicity,and ***,disruption of the blood-spinal cord barrier results in the release of inflammatory cytokines from specific cells and vessels.

关键词： acute injuries nerves

Tidal effects based on a GUP-induced effective metric

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Communications in Theoretical Physics 2024年第9期76卷 63-72页

作者： Soon-tae Hong Yong-Wan Kim Young-Jai park Center for Quantum Spacetime and Department of Physics Sogang UniversitySeoul 04107Republic of Korea Department of Physics and Research Institute of Physics and Chemistry Jeonbuk National UniversityJeonju 54896Republic of Korea Department of Physics Sogang UniversitySeoul 04107Republic of Korea

In this paper,we study tidal forces in the Schwarzschild black hole,whose metric explicitly includes a generalized uncertainty principle(GUP)*** also investigate interesting features of the geodesic equations and tidal effects that are dependent on the GUP parameterαrelated to a minimum ***,by solving the geodesic deviation equations explicitly with appropriate boundary conditions,we show thatαin the effective metric affects both the radial and angular components of the geodesic equation,particularly near the singularities.

关键词： generalized uncertainty principle geodesic deviation equation effective metric