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Site-Specific Growth of Width-Tailored Graphene Nanoribbons on Insulating Substrates
Song, Wooseok,Kim, Soo Youn,Kim, Yooseok,Kim, Sung Hwan,Lee, Su Il,Song, Inkyung,Jeon, Cheolho,Park, Chong-Yun American Chemical Society 2012 The Journal of Physical Chemistry Part C Vol.116 No.37
<P>The band-gap opening in graphene is a key factor in developing graphene-based field-effect transistors. Although graphene is a gapless semimetal, a band gap opens when graphene is formed into a graphene nanoribbon (GNR). Moreover, the band-gap energy can be manipulated by the width of the GNR. In this study, we propose a site-specific synthesis of a width-tailored GNR directly onto an insulating substrate. Predeposition of a diamond-like carbon nanotemplate onto a SiO<SUB>2</SUB>/Si wafer via focused ion-beam-assisted chemical vapor deposition is first utilized for growth of the GNR. These results may present a feasible route for growing a width-tailored GNR onto a specific region of an insulating substrate.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2012/jpccck.2012.116.issue-37/jp303409c/production/images/medium/jp-2012-03409c_0008.gif'></P>
Synthesis of Bandgap-Controlled Semiconducting Single-Walled Carbon Nanotubes
Song, Wooseok,Jeon, Cheolho,Kim, Yoo Seok,Kwon, Young Taek,Jung, Dae Sung,Jang, Sung Won,Choi, Won Chel,Park, Jin Sung,Saito, Riichiro,Park, Chong-Yun American Chemical Society 2010 ACS NANO Vol.4 No.2
<P>Bandgap-controlled semiconducting single-walled carbon nanotubes (s-SWNTs) were synthesized using a uniquely designed catalytic layer (Al<SUB>2</SUB>O<SUB>3</SUB>/Fe/Al<SUB>2</SUB>O<SUB>3</SUB>) and conventional thermal chemical vapor deposition. Homogeneously sized Fe catalytic nanoparticles were prepared on the Al<SUB>2</SUB>O<SUB>3</SUB> layer and their sizes were controlled by simply modulating the annealing time <I>via</I> heat-driven diffusion and subsequent evaporation of Fe at 800 °C. Transmission electron microscopy and Raman spectroscopy revealed that the synthesized SWNTs diameter was manipulated from 1.4 to 0.8 nm with an extremely narrow diameter distribution below 0.1 nm as the annealing time is increased. As a result, the bandgap of semiconducting SWNTs was successfully controlled, ranging from 0.53 to 0.83 eV, with a sufficiently narrow energy distribution, which can be applied to field-effect transistors based on SWNTs.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2010/ancac3.2010.4.issue-2/nn901135b/production/images/medium/nn-2009-01135b_0007.gif'></P>
Song, Wooseok,Kim, Yong-Hak,Sim, Se-Hoon,Hwang, Soonhye,Lee, Jung-Hyun,Lee, Younghoon,Bae, Jeehyeon,Hwang, Jihwan,Lee, Kangseok Oxford University Press 2014 Nucleic acids research Vol.42 No.7
<P>Here, we report a resistance mechanism that is induced through the modulation of 16S ribosomal RNA (rRNA) processing on the exposure of <I>Escherichia coli</I> cells to aminoglycoside antibiotics. We observed decreased expression levels of RNase G associated with increased RNase III activity on <I>rng</I> mRNA in a subgroup of <I>E. coli</I> isolates that transiently acquired resistance to low levels of kanamycin or streptomycin. Analyses of 16S rRNA from the aminoglycoside-resistant <I>E. coli</I> cells, in addition to mutagenesis studies, demonstrated that the accumulation of 16S rRNA precursors containing 3–8 extra nucleotides at the 5’ terminus, which results from incomplete processing by RNase G, is responsible for the observed aminoglycoside resistance. Chemical protection, mass spectrometry analysis and cell-free translation assays revealed that the ribosomes from <I>rng</I>-deleted <I>E. coli</I> have decreased binding capacity for, and diminished sensitivity to, streptomycin and neomycin, compared with wild-type cells. It was observed that the deletion of <I>rng</I> had similar effects in <I>Salmonella enterica</I> serovar Typhimurium strain SL1344. Our findings suggest that modulation of the endoribonucleolytic activity of RNase III and RNase G constitutes a previously uncharacterized regulatory pathway for adaptive resistance in <I>E. coli</I> and related gram-negative bacteria to aminoglycoside antibiotics.</P>
다공성 니켈 나노 구조체를 이용한 3차원 그래핀의 합성
송우석 ( Wooseok Song ),명성 ( Sung Myung ),이선숙 ( Sun Sook Lee ),임종선 ( Jongsun Lim ),안기석 ( Ki-seok An ) 한국복합재료학회 2016 Composites research Vol.29 No.4
그래핀은 저차원 구조에서 기인하는 우수한 특성으로 인해 슈퍼커패시터의 전극소재로 응용이 가능한 소재이다. 본 연구에서는 2차원 구조인 그래핀의 비 표면적 향상을 위해 다공성 니켈 나노구조체 표면에 열 화학기 상증착법과 마이크로웨이브 플라즈마 화학기상증착법을 이용하여 3차원의 그래핀을 합성하였다. 주사전자현미경, 라만 분광법, X-선 광전자 분광법을 통해 합성된 그래핀의 구조적, 화학적 특성을 분석한 결과, 3차원 구조의 우수한 결정성을 지니는 다중층 그래핀이 다양한 기판 위에 합성된 것을 확인할 수 있었다. Graphene has been a valuable candidate for use as electrodes for supercapacitors. In order to improve the surface area of graphene, three-dimensional graphene was synthesized on porous Ni nanostructure using thermal chemical vapor deposition and microwave plasma chemical vapor deposition. The structural and chemical characterization of synthesized graphene was performed by scanning electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. It was confirmed that three-dimensional and high-crystalline multilayer graphene onto various substrates was synthesized successfully.