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Direct Growth of Graphene on Insulating Substrate by Laminated (Au/Ni) Catalyst Layer

  • Ko, Yong Hun;Kim, Yooseok;Jung, Daesung;Park, Seung Ho;Kim, Ji Sun;Shim, Jini;Yun, Hyeju;Song, Wooseok;Park, Chong-Yun
    • Applied Science and Convergence Technology
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    • v.24 no.4
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    • pp.117-124
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    • 2015
  • A direct growth method of graphene on insulating substrate without catalyst etching and transfer process was developed using Au/Ni/a-C catalyst system. During the growth process, behavior of the Au/Ni catalyst was investigated using EDX, XPS, SEM, and Raman spectroscopy. The Au/Ni catalyst layer was evaporated during growth process of graphene. The graphene film was composed mono-layer flakes. The transmittance of the graphene film was ~80.6%.

Solution NMR spectroscopy for investigation of liquid-liquid phase separation

  • Saio, Tomohide;Okumura, Masaki;Lee, Young-Ho
    • Journal of the Korean Magnetic Resonance Society
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    • v.24 no.2
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    • pp.47-52
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    • 2020
  • Liquid-liquid phase separation (LLPS) of biomolecules, a newly-found phase behavior of molecules in the liquid phase, has shown to its relationship to various biological function and misfolding diseases. Extensive studies have increasingly revealed a general mechanism of LLPS and characterized the liquid droplet; ho wever, intermolecular interactions of proteins and structural states of LLPS-inducing proteins inside of the droplet remain largely unknown. Solution NMR spectroscopy has emerged as a powerful approach as it provides invaluable information on protein intermolecular interactions and structures at the atomic and residue level. We herein comprehensively address useful techniques of solution NMR including the effect of paramagnetic relaxation enhancement for the study on the LLPS and droplet based on recent studies.

The design study of optics and opto-mechanics for Lyman-a sun camera of scientific satellite

  • Kim, Kil-Seon;Lee, J.G.;Lee, Y.H.;Rim, Cheon-Seog;Jang, Min-Hwan;Oh, Oh;Park, Jung-Sun;Lee, Woo-Yun;Kim, Geon-Hee
    • Proceedings of the Optical Society of Korea Conference
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    • 2004.07a
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    • pp.64-67
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    • 2004
  • The optics and opto-mechanics are disigned for imaging the sun at Lyman-${\alpha}$ line for scientific satellite. The optics are composed of conic mirrors. In order to block stary light. the new baffle design method is suggested. And we will present the opto-mechanics for this scientific satellite.

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Cd(II) and Zn(II) Complexes Containing N,N'-Bidentate N-(Pyridin-2-ylmethylene)cyclopentanamine: Synthesis, Characterisation and Methyl Methacrylate Polymerisation

  • Song, Yujin;Kim, Dongil;Lee, Ha-Jin;Lee, Hyosun
    • Bulletin of the Korean Chemical Society
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    • v.35 no.10
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    • pp.2929-2934
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    • 2014
  • The reaction between $[CdBr_2{\cdot}4H_2O]$ and anhydrous $[ZnCl_2]$ with N,N'-bidentate N-(pyridin-2-ylmethylene)-cyclopentanamine (impy) in ethanol yields dimeric $[(impy)Cd({\mu}-Br)Br]_2$ and monomeric $[(impy)ZnCl_2]$ complexes, respectively. The X-ray crystal structure of Cd(II) and Zn(II) complexes revealed that the cadmium atom in $[(impy)Cd({\mu}-Br)Br]_2$ and zinc in $[(impy)ZnCl_2]$ formed a distorted trigonal-bipyramidal and tetrahedral geometry, respectively. Both complexes showed moderate catalytic activity for the polymerisation of methyl methacrylate (MMA) in the presence of modified methylaluminoxane (MMAO), with polymethylmethacrylate (PMMA) syndiotacticity of about 0.70.

Structures of Butylthiolate Self-Assembled Monolayers on Au(111) with Gold Adatoms

  • Ryu, Seol;Kang, Jee-Won;Han, Young-Kyu;Lee, Yoon-Sup
    • Bulletin of the Korean Chemical Society
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    • v.32 no.10
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    • pp.3614-3617
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    • 2011
  • A density functional theory method with the local basis set was employed to perform slab calculations to study thiolate-induced surface reconstruction structures of butylthiolates (ButS) with c($4{\times}2$) superlattice of the Au(111) surface. The slab calculations indicate that the most stable adsorption structure is the ButS-Au (adatom)-SBut complex form, which is in good agreement with the reported experiments and theoretical results for thiolates with shorter alkyl chains. The cis form of ButS-Au (adatom)-SBut motifs is preferred by 0.11 eV with respect to the trans form, and by 0.15 eV over the mixed cis-trans configurations due to the steric hindrance between adjacent butyl groups. It appears that the motif of Au adatom on the Au(111) surface is favored even for butylthiolate.

Fabrication and Characterization of $High-T_c$ Superconducting Single Channel Flux Flow Transistor using the Atomic Force Microscope TiO Cantilever Tip (원자힘 주사현미경 TiO 탐침을 이용한 고온 초전도 단일채널 자속 흐름 트랜지스터의 제작 및 특성 해석)

  • Ko, Seok-Cheol;Kang, Hyeong-Gon;Lim, Sung-Hun;Lee, Jong-Hwa;Lee, Hae-Sung;Han, Byoung-Sung
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2004.07a
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    • pp.101-104
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    • 2004
  • We have fabricated a channel of superconducting flux flow transistor(SFFT) using the voltage-biased atomic force microscope(AFM) TiO tip and performed numerical simulations for the SFFT controlled by the magnetic field with a control current. The critical current density in a channel of the fabricated SFFT was decreased with the applied current by a control line. By comparing the measured with theoretical results, we showed a possibility of fabrication of an SFFT with a nano-channel using AFM anodization process technique.

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Mobility of Microplastics in Subsurface Environments: Current Knowledge and Perspectives (지중환경에서 미세플라스틱의 이동성에 대한 고찰)

  • Kim, Youn-Tae;Han, Weon Shik;Yoon, Hye-On
    • Journal of Soil and Groundwater Environment
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    • v.24 no.3
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    • pp.1-12
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    • 2019
  • Plastics have become essential materials in human life for several decades. Meanwhile, the inadvertent spread of plastic debris from the use of many plastic products has raised global environmental concerns. The risk of microplastics in subsurface environment has received little attention because soil is considered to confine microplastics within the matrix. However, the concentration of microplastics in soil unavoidably increased as a result of an increase in plastic production and use. Based on lab experiments, several researches claimed that microplastics possibly penentrate soil layers. Recently, a few researches reported the occurrence of microplastics in groundwater. This study reviewed the recent reports of microplastic occurrences in soil and groundwater, and the modeling studies for simulating transport of microplastics. Additionally, the difficulties and limits in microplastics researches in soil and groundwater are discussed. Finally, several perspectives on microplastic studies in subsurface environment are suggested.