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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>
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>
웹 어셈블리 활용한 웹 기반 블록체인 네트워크 시스템 설계 및 구현
송우석(Wooseok Song),정현준(Hyunjun Jung),정동원(Dongwon Jeong) 한국정보기술학회 2022 한국정보기술학회논문지 Vol.20 No.12
This paper measure the block generation performance of blockchain between javascript and web assembly in web enviroment and propose a method to maintain a blockchain system in a web environment. As the recent growth of blockchain, it is necessary to install a client software to participate in most blockchain networks. This is a factor that can hinder the convenience for popularization of blockchain technology. Therefore, this paper proposes a web-based blockchain system to provide users with high accessibility. In the experiment, the web assembly showed about 57.62% better performance than javascript in terms of blockchain block generation in the web environment. In addition, the proposed system shows that users can participate in the blockchain network through a browser and maintain the network by create and verify blocks.
웹 어셈블리를 활용한 웹 환경의 블록체인 활용 가능성 분석
송우석(Wooseok Song),정승원(Seungwon Jeong),정현준(Hyunjun Jung),정동원(Dongwon Jeong) 한국정보기술학회 2022 Proceedings of KIIT Conference Vol.2022 No.6
최근 웹의 규모와 블록체인의 연구 범위는 지속적으로 커지고 있다. 자바스크립트의 한계를 보완하기 위한 새로운 표준으로 웹 어셈블리가 공개되었으며, 이는 새로운 유형의 저수준 바이트 코드이다. 웹 어셈블리를 사용하면 웹 환경에서 네이티브 환경과 비슷한 연산 속도를 보여줄 수 있다. 또한 웹 서비스에 블록체인을 도입하려는 시도도 이어지고 있으며, 기존 대비 다양한 측면에서의 효율 상승도 기대된다. 따라서 본 논문에서는 블록체인을 각각 네이티브 환경과 웹 어셈블리를 적용한 웹 환경으로 구현해 블록 생성 시간을 비교하고 웹환경에서의 블록체인 활용 가능성을 분석한다. Low-Level 난이도에도 웹 어셈블리를 이용한 경우 Low-Level에 17.93% 더욱 빨랐으며, High-Level의 경우 네이티브가 3.25% 더욱 빠른 성능을 보여주었다. 제약 조건을 만족한다면 다양한 웹 서비스에 웹 어셈블리를 적용한 블록체인 시스템을 적용할 수 있을 것으로 기대된다. Recently, the size of the web and the scope of research on blockchain are continuously increasing. Web assemblies have been released as a new standard to compensate for the limitations of JavaScript, a new type of low-level byte code. Web assemblies allow you to show computational speeds similar to native environments in a web environment In addition, attempts to introduce blockchain into web services are continuing, and efficiency in various aspects is expected to increase compared to the previous one. Therefore, in this paper, blockchain is implemented as a native environment and a web environment applying a web assembly, respectively, to compare block creation time and analyze the possibility of using blockchain in a web environment. In casae of using Web Assembly, it’s 17.93% faster at Low-Level, but in case of High-Level, Native showed 3.25% faster performance, If the constraints are satisfied, it is expected that the blockchain system using web assembly can be applied to various web services.