http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
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>
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>
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>
축소형 연소기에서 임계 조건에 따른 화염구조 가시화 시험
송우석(Wooseok Song),구자예(Jaye Koo) 한국추진공학회 2019 한국추진공학회 학술대회논문집 Vol.2019 No.5
고성능 액체로켓엔진 개발을 위해서는 고온, 고압의 연소가 필수적이다. 본 논문에서는 축소형 연소기에서 임계 조건에 따른 화염구조를 가시화하는 것이 목표이다. 전단 동축 분사기를 이용하여 산화제는 기체산소를 사용하였고 연료는 액체 케로신을 사용하였다. 화염구조를 촬영하기 위해 탄화수소계 연료 연소에서 생성되는 CH* 화학발광 성분을 밴드패스필터 및 고속카메라를 이용하여 가시화하였다. 연소불안정 정도를 계산하여 아임계/초임계 연소조건에서 안정된 화염을 확인하였다. 안정된 연소조건에서 화염두께는 아임계 연소조건보다 초임계 연소조건에서 작게 측정되었다.. The high temperature and pressure in the combustion chamber is essential to develop the liquid rocket engine for a high performance. The objective of this study is to visualize the flame structure under subcritical and supercritical conditions using a subsclae combustor. The gaseous oxygen and liquid kerosene were used for propellants with the shear coaxial injector. In order to detect the flame structure, CH* chemiluminescience images, which is one of representative species during the combustion process, was recorded using band-pass filter and high-speed camera. A stable flame was confirmed by calculating the combustion instability intensity under subcritical and supercritical conditions. The flame thickness in the case of supercritical condition was thiner than in the case of subcritical condition.