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Surface plasmon enhancement of photoluminescence in photo-chemically synthesized graphene quantum dot and Au nanosphere

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Nano Research 2016年第6期9卷 1866-1875页

作者： Byeongho Park Sun jun Kim Ji Soo Sohn Min Sik Nam Shinill Kang seong chan jun School of Mechanical Engineering Yonsei University 50 Yonsei-ro Seodaemun-gu Seou1120-749 Republic of Korea

Graphene quantum dots （GQDs） are promising candidates for potential applications such as novel optoelectronic devices and bio-imaging. However, insufficient light absorption to exhibit their intriguing characteristics. The strong confinement of light caused by the Au nanoparticles as an antenna can considerably boost the light absorption. With the assistance of ultraviolet irradiation, we prepared bluish-green luminescent nanospheres by the hybridiza- tion of GQD and Au nanoparticles （GQD/Au）. These nanospheres showed a photoluminescence quantum yield of up to 26.9%. The GQD/Au nanospheres were synthesized using a solution of GQDs and HAuC14 by a photochemical method with the reduction of GQDs and the formation of metallic Au. The GQDs and Au nanopartides self-assembled and aggregated into nanospheres via aurophilicity and hydrogen bonding interactions. The average size of the GQD/Au nanospheres was found to be in the range of 150-170 nm, which is much larger than that of the pristine GQDs （4-7 nm）. The GQD/Au nanospheres exhibited an absorption band at 541 nm, which indicates the presence of Au in the nanospheres. The typical absorbance features of GQDs were observed near 236 and 303 nrn. The photoluminescence characteristics were investigated using the excitation and emission spectra. The GQD/Au nanospheres exhibited two emission peaks at 468 and 529 nm in the visible range. The green fluorescent peak located at 529 nm was newly generated by the hybridization. The GQD/Au nanospheres showed an emission efficiency which was two times more than that of the intrinsic GQDs. The reason for this increase was the surface plasmon resonance from the Au particles, which improved the fluorescence property of the resulting nanospheres. These nanospheres can be perceived as outstanding candidates for applications such as displays, optoelectronic devices, and imaging of the biological samples with high emission intensity.

关键词： graphene quantum dot gold nanosphere photoluminescence UV irradiation

High-concentration dispersions of exfoliated MoS2 sheets stabilized by freeze-dried silk fibroin powder

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Nano Research 2016年第6期9卷 1709-1722页

作者： HeungBo Sim JiYong Lee Byeongho Park Sun jun Kirn Shinill Kang ,WonHyoung Ryu seong chan jun School of Mechanical Engineering Yonsei University Seoul 120-749 Republic of Korea

Liquid-phase exfoliation （LPE） is an attractive method for the scaling-up of exfoliated MoS2 sheets compared to chemical vapor deposition and mechanical cleavage. However, the MoS2 nanosheet yield from LPE is too small for practical applications. We report a facile method for the scaling-up of exfoliated MoS2 nanosheets using freeze-dried silk fibroin powders. Compared to MoS2 dispersion in the absence of silk fibroin powder, sonicated MoS2 dispersions with silk fibroin powder （MoSJSilk dispersion） show noticeably higher exfoliated MoS2 nanosheet yields, with suspended MoS2 concentrations in MoS2/Silk dispersions sonicated for 2 and 5 h of 1.03 and 1.39 ***-1, respectively. The MoS2 concentration in the MoS2/Silk dispersion after centrifugation above 10,000 rpm is more than four times that without the silk fibroin. The size of the dispersed silk fibroin is controlled by the change of centrifugation rate, showing the removal of silk fibroin above tens of micrometers in size after centrifugation at 2,000 rpm. Size-controlled silk fibroin biomolecules combined with MoS2 nanosheets are expected to increase the practical use of such materials in fields related to tissue engineering, biosensors and electrochemical electrodes. Atomic force microscopy and Raman spectroscopy provide the height of the MoS2 nanosheets spin-cast from MoS2/Silk dispersions, showing thicknesses of 3--6 nm. X-ray photoelectron spectroscopy and X-ray diffraction indicate that the outermost surface layer of the hydrophobic MoS2 crystals interact with oxygen-containing functional groups that exist in the hydrophobic part of silk fibroins. The amphiphilic properties of silk fibroin combined with the MoS2 nanosheets stabilize dispersions by enhancing solvent-material interactions. The large quantities of exfoliated MoS2 nanosheets suspended in the as-synthesized dispersions can be utilized for the fabrication of vapor and electrochemical devices requiring high MoS2 nanosheets contents.

关键词： MoS2 nanosheet liquid-phase exfoliation freeze-dried silk fibroin powder amount of suspended MoB2 sheet stabilized dispersion

Enhancing Identity Protection in Metaverse-Based Psychological Counseling System

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Computers, Materials & Continua 2024年第1期78卷 617-632页

作者： jun Lee Hanna Lee seong chan Lee Hyun Kwon Department of Game Software Hoseo UniversityAsan-si31499Korea Yatav Enter Seoul04799Korea Department of Artificial Intelligence and Data Science Korea Military AcademySeoul01805Korea

Non-face-to-face psychological counseling systems rely on network technologies to anonymize information regard-ing client ***,these systems often face challenges concerning voice data leaks and the suboptimal communication of the client’s non-verbal expressions,such as facial cues,to the *** study proposes a metaverse-based psychological counseling system designed to enhance client identity protection while ensuring efficient information delivery to counselors during non-face-to-face *** proposed systemincorporates a voicemodulation function that instantlymodifies/masks the client’s voice to safeguard their ***,it employs real-time client facial expression recognition using an ensemble of decision trees to mirror the client’s non-verbal expressions through their avatar in the metaverse *** system is adaptable for use on personal computers and smartphones,offering users the flexibility to access metaverse-based psychological counseling across diverse *** performance evaluation of the proposed system confirmed that the voice modulation and real-time facial expression replication consistently achieve an average speed of 48.32 frames per second or higher,even when tested on the least powerful smartphone ***,a total of 550 actual psychological counseling sessions were conducted,and the average satisfaction rating reached 4.46 on a 5-point *** indicates that clients experienced improved identity protection compared to conventional non-face-to-face metaverse counseling ***,the counselor successfully addressed the challenge of conveying non-verbal cues from clients who typically struggled with non-face-to-face psychological *** proposed systemholds significant potential for applications in interactive discussions and educational activities in the metaverse.

关键词： Metaverse counseling system face tracking identity protection

Dipole-assisted carrier transport in bis(trifluoromethane) sulfonamide-treated O-ReS_(2) field-effect transistor

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Nano Research 2021年第7期14卷 2207-2214页

作者： Jae Young Park SangHyuk Yoo Byeongho Park Taekyeong Kim Young Tea Chun Jong Min Kim Keonwook Kang Soo Hyun Lee seong chan jun Department of Mechanical Engineering Yonsei UniversitySeoul 03722Republic of Korea Center for Biomicrosystem Brain Science InstituteKorea Institute of Science and TechnologySeoul 02792Republic of Korea Sensor System Research Center Korea Institute of Science and TechnologySeoul 02792Republic of Korea Department of Physics Hankuk University of Foreign StudiesYongin 17035Republic of Korea Division of Electronics and Electrical Information Engineering Korea Maritime and Ocean UniversityBusan 49112Republic of Korea Electrical Engineering Division Engineering Department University of CambridgeCambridgeCB3 OFAUK

We demonstrate the dipole-assisted carrier transport properties of bis(trifluoromethane)sulfonamide(TFSI)-treated O-ReS_(2) field-effect *** ReS_(2) was compared with defect-mediated ReS_(2) to confirm whether the presence of defects on the interface enhances the interaction between O-ReS_(2) and TFSI *** to the experiment,density functional theory(DFT)calculation was performed,and the result indicated that the charge transfer between TFSI and O-ReS_(2) is more sensitive to external electric fields than that between TFSI and pristine ReS_(2).After TFSI treatment,the drain current of O-ReS_(2) FET was significantly increased up to 1,113.4 times except in the range of−0.32–0.76 V owing to Schottky barrier modulation from dipole polarization of TFSI molecules,contrary to a significant degradation in device performance in pristine ReS_(2) ***,in the treated O-ReS_(2) device,the dipole direction was highly influenced by the voltage sweep direction,generating a significant area of hysteresis in I–V and transfer characteristics,which was further verified by the surface potential ***,the dipole state was enhanced according to the wavelength of the light source and *** results indicate that TFSI-treated ReS_(2) FET has large potential for use as next-generation memristor,memory,and photodetector.

关键词： Two-dimensional material ReS_(2) field-effect transistor TFSI superacid dipole

Electrically focus-tuneable ultrathin lens for high-resolution square subpixels

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Light(Science & Applications) 2020年第1期9卷 1066-1078页

作者： Sehong Park Gilho Lee Byeongho Park Youngho Seo Chae bin Park Young Tea Chun Chulmin Joo junsuk Rho Jong Min Kim James Hone seong chan jun School of Mechanical Engineering Yonsei University50 Yonsei-roSeodaemun-guSeoul 03722Republic of Korea Electrical Engineering Division Engineering DepartmentUniversity of Cambridge9 JJ Thomson AvenueCambridge CB3 OFAUK Department of Electronic Material Engineering Korea Maritime and Ocean UniversityBusan 49112Republic of Korea Department of Mechanical Engineering Pohang University of Science and Technology(POSTECH)77 Cheongam-roNam-guPohang 37673Republic of Korea Department of Chemical Engineering Pohang University of Science and Technology(POSTECH)77 Cheongam-roNam-guPohang 37673Republic of Korea Institute for Convergence Research and Education in Advanced Technology Yonsei University50 Yonsei-roSeodaemun-guSeoul 03722Republic of Korea Department of Mechanical Engineering Columbia University500 West 120th StreetMudd 220New YorkNY 10027USA

Owing to the tremendous demands for high-resolution pixel-scale thin lenses in displays,we developed a graphenebased ultrathin square subpixel lens(USSL)capable of electrically tuneable focusing(ETF)with a performance competitive with that of a typical mechanical refractive *** fringe field due to a voltage bias in the graphene proves that our ETF-USSL can focus light onto a single point regardless of the wavelength of the visible light—by controlling the carriers at the Dirac point using radially patterned graphene layers,the focal length of the planar structure can be adjusted without changing the curvature or position of the lens.A high focusing efficiency of over 60% at a visible wavelength of 405 nm was achieved with a lens thickness of change of 19.42% in the focal length with a 9% increase in transmission was exhibited under a driving *** design is first presented as an ETF-USSL that can be controlled in pixel units of flat panel displays for visible *** can be easily applied as an add-on to high resolution,slim displays and provides a new direction for the application of multifunctional autostereoscopic displays.

关键词： visible driving competitive

Multiplexed DNA-functionalized graphene sensor with artificial intelligence-based discrimination performance for analyzing chemical vapor compositions

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Microsystems & Nanoengineering 2023年第2期9卷 113-125页

作者： Yun Ji Hwang Heejin Yu Gilho Lee Iman Shackery Jin seong Youngmo jung Seung-Hyun Sung Jongeun Choi seong chan jun School of Mechanical Engineering Yonsei University500Yonsei-roSeodaemun-guSeoul 03722Republic of Korea

This study presents a new technology that can detect and discriminate individual chemical vapors to determine the chemical vapor composition of mixed chemical composition in situ based on a multiplexed DNA-functionalized graphene(MDFG)nanoelectrode without the need to condense the original vapor or target *** the best of our knowledge,our artificial intelligence(Al)-operated arrayed electrodes were capable of identifying the compositions of mixed chemical gases with a mixed ratio in the early *** innovative technology comprised an optimized combination of nanodeposited arrayed electrodes and artificial intelligence techniques with advanced sensing capabilities that could operate within biological limits,resulting in the verification of mixed vapor chemical *** selective sensors that are tolerant to high humidity levels provide a target for"breath chemovapor fingerprinting"for the early diagnosis of *** feature selection analysis achieved recognition rates of 99%and above under low-humidity conditions and 98%and above under humid conditions for mixed chemical *** 1D convolutional neural network analysis performed better,discriminating the compositional state of chemical vapor under low-and high-humidity conditions almost *** study provides a basis for the use of a multiplexed DNA-functionalized graphene gas sensor array and artificial intelligence-based discrimination of chemical vapor compositions in breath analysis applications.

关键词： humidity functional intelligence

A MEMS ultrasound stimulation system for modulation of neural circuits with high spatial resolution in vitro

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Microsystems & Nanoengineering 2019年第1期5卷 356-366页

作者： jungpyo Lee Kyungmin Ko Hyogeun Shin Soo-Jin Oh CJustin Lee Namsun Chou Nakwon Choi Min Tack Oh Byung Chul Lee seong chan jun Il-Joo Cho Center for BioMicrosystems Brain Science InstituteKorea Institute of Science and Technology(KIST)Seoul 02792Republic of Korea School of Mechanical Engineering Yonsei UniversitySeoul 03722Republic of Korea Division of Bio-Medical Science&Technology KIST SchoolKorea University of Science and Technology(UST)Seoul 02792Republic of Korea Center for Neuroscience Brain Science InstituteKorea Institute of Science and Technology(KIST)Seoul 02792Republic of Korea Convergence Research Center for Diagnosis Treatmentand Care System of DementiaKorea Institute of Science and Technology(KIST)Seoul 02792Republic of Korea Center for Glia-Neuron Interaction Korea Institute of Science and Technology(KIST)Seoul 02792Republic of Korea KU-KIST Graduate School of Converging Science and Technology Korea UniversitySeoul 02841Republic of Korea Division of Bio-Medical Science&Technology KIST SchoolKorea University of Science and TechnologyUSTYuseong-guDaejeon 34113Republic of Korea

Neuromodulation by ultrasound has recently received attention due to its noninvasive stimulation capability for treating brain *** there have been several studies related to ultrasonic neuromodulation,these studies have suffered from poor spatial resolution of the ultrasound and low repeatability with a fixed condition caused by conventional and commercialized ultrasound *** addition,the underlying physics and mechanisms of ultrasonic neuromodulation are still *** determine these mechanisms and accurately modulate neural circuits,researchers must have a precisely controllable ultrasound transducer to conduct experiments at the cellular ***,we introduce a new MEMS ultrasound stimulation system for modulating neurons or brain slices with high spatial *** piezoelectric micromachined ultrasonic transducers(pMUTs)with small membranes(submm membranes)generate enough power to stimulate neurons and enable precise modulation of neural *** designed the ultrasound transducer as an array structure to enable localized modulation in the target *** addition,we integrated a cell culture chamber with the system to make it compatible with conventional cell-based experiments,such as in vitro cell cultures and brain *** this work,we successfully demonstrated the functionality of the system by showing that the number of responding cells is proportional to the acoustic intensity of the applied *** also demonstrated localized stimulation capability with high spatial resolution by conducting experiments in which cocultured cells responded only around a working transducer.

关键词： neural stimulation system

SARS-CoV-2 aberrantly elevates mitochondrial bioenergetics to induce robust virus propagation

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Signal Transduction and Targeted Therapy 2024年第6期9卷 2702-2715页

作者： Hye Jin Shin Wooseong Lee Keun Bon Ku Gun Young Yoon Hyun-Woo Moon Chonsaeng Kim Mi-Hwa Kim Yoon-Sun Yi Sangmi jun Bum-Tae Kim Jong-Won Oh Aleem Siddiqui seong-jun Kim Department of Convergent Research of Emerging Virus Infection Korea Research Institute of Chemical TechnologyDaejeon 34114Republic of Korea Gyeongnam Biohealth Research Center Gyeongnam Branch InstituteKorea Institute of ToxicologyJinju 52834Republic of Korea Center for Research Equipment Korea Basic Science InstituteCheongjuChungcheongbuk-do 28119Republic of Korea Department of Biotechnology Yonsei UniversitySeoul 03722Republic of Korea Division of Infectious Diseases School of MedicineUniversity of CaliforniaSan DiegoLa JollaCA 92093USA Present address:Department of Microbiology Chungnam National University School of MedicineDaejeon 35015Republic of Korea

Severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)is a‘highly transmissible respiratory pathogen,leading to severe multiorgan ***,knowledge regarding SARS-CoV-2-induced cellular alterations is *** this study,we report that SARSCoV-2 aberrantly elevates mitochondrial bioenergetics and activates the EGFR-mediated cell survival signal cascade during the early stage of viral ***-CoV-2 causes an increase in mitochondrial transmembrane potential via the SARS-CoV-2 RNAnucleocapsid cluster,thereby abnormally promoting mitochondrial elongation and the OXPHOS process,followed by enhancing ATP ***,SARS-CoV-2 activates the EGFR signal cascade and subsequently induces mitochondrial EGFR trafficking,contributing to abnormal OXPHOS process and viral *** EGFR inhibitors remarkably reduce SARS-CoV-2 propagation,among which vandetanib exhibits the highest antiviral *** of SARS-CoV-2-infected cells with vandetanib decreases SARS-CoV-2-induced EGFR trafficking to the mitochondria and restores SARS-CoV-2-induced aberrant elevation in OXPHOS process and ATP generation,thereby resulting in the reduction of SARS-CoV-2 ***,oral administration of vandetanib to SARS-CoV-2-infected hACE2 transgenic mice reduces SARS-CoV-2 propagation in lung tissue and mitigates SARS-CoV-2-induced lung *** also exhibits potent antiviral activity against various SARS-CoV-2 variants of concern,including alpha,beta,delta and omicron,in in vitro cell culture *** together,our findings provide novel insight into SARS-CoV-2-induced alterations in mitochondrial dynamics and EGFR trafficking during the early stage of viral infection and their roles in robust SARS-CoV-2 propagation,suggesting that EGFR is an attractive host target for combating COVID-19.

关键词： alterations aberrant thereby

Role of marine natural products in the development of antiviral agents against SARS‑CoV‑2:potential and prospects

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Marine Life Science & Technology 2024年第2期6卷 280-297页

作者： D.P.Nagahawatta N.M.Liyanage Thilina U.Jayawardena H.H.A.C.K.Jayawardhana seong‑Hun Jeong Hyung‑jun Kwon You‑Jin Jeon Department of Marine Life Sciences Jeju National UniversityJeju 690-756Republic of Korea Department of Chemistry Biochemistry and PhysicsUniversitédu QuébecàTrois-RivièresTrois-RivièresQC G8Z 4M3Canada Marine Science Institute Jeju National UniversityJeju 63333Republic of Korea Functional Biomaterial Research Center Korea Research Institute of Bioscience and BiotechnologyJeongeup-siRepublic of Korea

A novel coronavirus,known as severe acute respiratory syndrome coronavirus 2(SARS-CoV-2),has surfaced and caused global concern owing to its ***-CoV-2 is the causative agent of coronavirus disease 2019;however,it was only discovered at the end of the year and was considered a pandemic by the World Health ***,the develop-ment of novel potent inhibitors against SARS-CoV-2 and future outbreaks is urgently *** naturally occurring bioactive substances have been studied in the clinical setting for diverse *** intricate infection and replication mechanism of SARS-CoV-2 offers diverse therapeutic drug targets for developing antiviral medicines by employing natural products that are safer than synthetic *** natural products(MNPs)have received increased attention in the development of novel drugs owing to their high diversity and ***,this review article investigates the infection and replication mechanisms,including the function of the SARS-CoV-2 genome and ***,we highlighted anti-SARS-CoV-2 therapeutic intervention efforts utilizing MNPs and predicted SARS-CoV-2 inhibitor design.

关键词： SARS-CoV-2 Marine natural products Drug targets Inhibitors