Microbacterium xylanilyticum sp. nov., a xylan-degrading bacterium isolated from a biofilm

Kim, Kwang Kyu,Park, Hye Yoon,Park, Wooshin,Kim, In S.,Lee, Sung-Taik Microbiology Society 2005 International journal of systematic and evolutiona Vol.55 No.5

<P>A novel xylan-degrading bacterium, S3-E<SUP>T</SUP>, was isolated from the biofilm of a membrane bioreactor. The cells of this strain were Gram-positive, non-motile, non-spore-forming rods, produced primary branches and formed yellow colonies on nutrient agar. The strain had chemotaxonomic markers that were consistent with classification in the genus <I>Microbacterium</I>, i.e. MK-12, MK-11 and MK-13 as the major menaquinones, predominant iso- and anteiso-branched cellular fatty acids, glucose and galactose as the cell-wall sugars, peptidoglycan-type B2<I>β</I> with glycolyl residues and a DNA G+C content of 69·7 mol%. Phylogenetic analysis, based on 16S rRNA gene sequencing, showed that strain S3-E<SUP>T</SUP> is most similar to <I>Microbacterium hominis</I> IFO 15708<SUP>T</SUP> and <I>Microbacterium foliorum</I> DSM 12966<SUP>T</SUP> (97·6 and 97·4 % sequence similarity, respectively), and that it forms a separate lineage with <I>M. hominis</I> in the genus <I>Microbacterium</I>. DNA-DNA hybridization results and phenotypic properties showed that strain S3-E<SUP>T</SUP> could be distinguished from all known <I>Microbacterium</I> species and represented a novel species, for which the name <I>Microbacterium xylanilyticum</I> sp. nov. is proposed; the type strain is S3-E<SUP>T</SUP> (=DSM 16914<SUP>T</SUP>=KCTC 19079<SUP>T</SUP>).</P>

독성물질의 세포사 기전 및 세포사 유발물질의 검색법 개발에 관한 연구(Ⅰ) : 독성물질로 인한 파킨슨병 모델에서의 세포사 기전 연구 Study on the cell-death mechanisms of toxin-induced parkinsonism

강태석,김종민,서경원,김영옥,김준규,오재호,이윤동,김규봉,오정자,송연정,임종준,전범석,문전옥,최광식 식품의약품안전청 2000 식품의약품안전청 연보 Vol.4 No.-

MPTP 독성물질이 도파민성 신경세포에 선택적으로 작용하여 산화성 손상에 의한 신경세포사를 일으키는 것을 이용하여 파킨슨병의 동물모델을 만들고, 이를 통해서 아폼토시스를 비롯한 포사의 기전에 대한 연구 및 너코틴의 신경세포 보호효과 여부를 판정하는 실험을 병행하고자 하였다. 파킨슨꾐의 동물모델을 MPTf 독성 물질을 이용하여 확립하였으며, MPTP(30mgag, i.p.)를 투여한 후 1, 2,3, 4, 5일째 흑질 조직을 채춰하여 tarm로 박걸하여 tyrosine hydroxylase 면역조직화학염색을 수행하여 cell countif우한 결과, control은 57.635ce11s, 1일째 친.OfDells,2일째 57.9±6cells,3일릴 없.3±죠ells, 4일째 49.0츠3cells, 5일째 39.4±Scells료 4, 3일째 뚜렷한 신경세포 수의 감소를 보였다. 신경세포사 기전 규명을 위한 아폼토시스 분걱에서는 벼PTP 투여 후 1, 2, 3, 4, 5일째 조직을 채취하여 Hoechst staining, TUNEL staining을 수곡하였는데 양성 반응을 보인 신경세포는 관찰되지 않아. 아폼토시스로 인한 세포사가 관찰되지 않았다. bIPTP 파킨슨병 동물모델에서 nicotine 보호효과 탐색에 관한 실험은 nicat푸e 0.2mgAg을 5일 퐁안 투여 후 리『fP(30mgag)를 CS7Bt/6 마은스에 복강 내주사로 nicotine과 병용 투여한 후 1, 2, 3, 4, 5일째 뇌를 적출하땄다. 신경세포사가 뚜렷이 관찰되기 시작하는 4, 5일째의 신경세포 수의 감소 정도를 20. 30% 정도 약화시키는 경향을 보였으나, nicotine 보호효과에 대한 추가 실헝이 현재 수행 중에 있다. The cause of Parkinson's disease (PD) is largely unknown. However, free radical toxicit? may plaf a role ip. the degeneration of substantia nigra, which is the Hajorfocus of pathological damages in PD. Recently, a neuroprotective effect of nicotine in PD has been suggested. Therefore, the mechanism of neurodegenerafion and protective potential o( nicotine in PD were investigated in the experimental modeB of Pll using a neurotoxin, C57BL/6mice were administered with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP, 30 mg/kg,j.p.). The degree of neurodegenerafion was determined by immunohistochemical stainiHB oftyrosine hydroxylase (TH). TH-positive cells on nigral sections were found 56.0 ±4, 57.9 ±6,52.315ce11s, 49.0±3cells, and 39,4±Scells at days 1, 2, 3, 4, 5, respectively (controls : 57.6±Scells). Hoechst and TUNEL staining showed no evidence of apoptosis. The exandnation on themice co-adrunistered with nicotine(0.2mgAg) and MPTP(30mgag) revealed a tendency ofnicotine protective effects. At days 4 and 5, the degree of TH-positive cells was decreased by20-30%, In corclusiffn, the role of apoptosis was not evidenced in this MPTP modeB of PB.The possible proteccon by nicotine should be elucidated with further studies.

반도체 패키지 봉지재용 에폭시 수지 조성물이 코팅된 알루미늄 패드의 임피던스 변화

이상훈,서광석,윤호규 한국마이크로전자및패키징학회 2000 추계 기술심포지움 논문집 Vol.2 No.1

Large-scale pattern growth of graphene films for stretchable transparent electrodes

Kim, Keun Soo,Zhao, Yue,Jang, Houk,Lee, Sang Yoon,Kim, Jong Min,Kim, Kwang S.,Ahn, Jong-Hyun,Kim, Philip,Choi, Jae-Young,Hong, Byung Hee Macmillan Publishers Limited. All rights reserved 2009 Nature Vol.457 No.7230

Problems associated with large-scale pattern growth of graphene constitute one of the main obstacles to using this material in device applications. Recently, macroscopic-scale graphene films were prepared by two-dimensional assembly of graphene sheets chemically derived from graphite crystals and graphene oxides. However, the sheet resistance of these films was found to be much larger than theoretically expected values. Here we report the direct synthesis of large-scale graphene films using chemical vapour deposition on thin nickel layers, and present two different methods of patterning the films and transferring them to arbitrary substrates. The transferred graphene films show very low sheet resistance of ∼280 Ω per square, with ∼80 per cent optical transparency. At low temperatures, the monolayers transferred to silicon dioxide substrates show electron mobility greater than 3,700 cm<SUP>2</SUP> V<SUP>-1</SUP> s<SUP>-1</SUP> and exhibit the half-integer quantum Hall effect, implying that the quality of graphene grown by chemical vapour deposition is as high as mechanically cleaved graphene. Employing the outstanding mechanical properties of graphene, we also demonstrate the macroscopic use of these highly conducting and transparent electrodes in flexible, stretchable, foldable electronics.

Carbon nanofibers decorated with FeO<i> _x </i> nanoparticles as a flexible electrode material for symmetric supercapacitors

Samuel, Edmund,Joshi, Bhavana,Jo, Hong Seok,Kim, Yong Il,An, Seongpil,Swihart, Mark T.,Yun, Je Moon,Kim, Kwang Ho,Yoon, Sam S. Elsevier 2017 Chemical Engineering Journal Vol. No.

<P><B>Abstract</B></P> <P>We have produced flexible, freestanding, and light weight mats of FeO<I> <SUB>x</SUB> </I>-decorated carbon nanofibers (CNFs) and demonstrated their use in supercapacitors with high energy and power density and excellent long term capacitance retention. Highly flexible carbon-iron oxide nanofibers were synthesized by electrospinning a solution of polyacrylonitrile (PAN), polymethylmethacrylate (PMMA), and iron acetylacetonate (FeAcAc), followed by annealing to carbonize the PAN, pyrolyze the PMMA to produce pores, and convert FeAcAc to FeO nanoparticles. The morphology of the FeO<I> <SUB>x</SUB> </I>/CNF composite was determined by scanning and transmission electron microscopies, which showed that the embedded FeO<I> <SUB>x</SUB> </I> nanoparticles were well distributed in the CNF electrode. We employed cyclic voltammetry, galvanostatic charge/discharge measurements, and electrochemical impedance spectroscopy to evaluate the electrochemical performance of symmetric supercapacitors prepared from the FeO<I> <SUB>x</SUB> </I>/CNF composite. The supercapacitors exhibited high specific capacitance (427F·g<SUP>−1</SUP> at 10mV·s<SUP>−1</SUP> and 436F·g<SUP>−1</SUP> at 1A·g<SUP>−1</SUP> in the optimal case) and good stability, retaining 89% of their initial capacitance after 5000 cycles at a current density of 1A·g<SUP>−1</SUP>. The optimal device achieved an energy density of 167Wh·kg<SUP>−1</SUP> at a power density of 0.75kW·kg<SUP>−1</SUP>, and an energy density of 66Wh·kg<SUP>−1</SUP> at a power density of 7.5kW·kg<SUP>−1</SUP>. These combinations of energy and power densities can meet the needs of many emerging supercapacitor applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Highly flexible FeO<SUB>x</SUB>-carbon nanocomposite nanofibers were fabricated. </LI> <LI> Freestanding FeO<I> <SUB>x</SUB> </I>-CNF showed excellent retention (89%) after 5000 cycles at 1A·g<SUP>−1</SUP>. </LI> <LI> A FeO<SUB>x</SUB>/CNF-based supercapacitor provides 436F·g<SUP>−1</SUP> of capacitance at 1A·g<SUP>−1</SUP>. </LI> <LI> Excellent uniform decoration of CNF with FeO<SUB>x</SUB> was demonstrated. </LI> </UL> </P>

Flexible and freestanding core-shell SnO_<i>x</i>/carbon nanofiber mats for high-performance supercapacitors

Samuel, Edmund,Joshi, Bhavana,Jo, Hong Seok,Kim, Yong Il,Swihart, Mark T.,Yun, Je Moon,Kim, Kwang Ho,Yoon, Sam S. ELSEVIER SCIENCE 2017 JOURNAL OF ALLOYS AND COMPOUNDS Vol.728 No.-

<P><B>Abstract</B></P> <P>We demonstrate the fabrication of core-shell SnO<SUB> <I>x</I> </SUB>/carbon nanofiber (CNF) composite mats via single-nozzle one-step electrospinning for use as flexible freestanding electrodes in supercapacitors. The freestanding and flexible nature of the composites is essential for their use in lightweight, portable, and foldable electronic devices and eliminates the need for a separate current collector. We fully characterized the structural and morphological properties of the SnO<SUB> <I>x</I> </SUB>/CNF mats and optimized the SnO<SUB> <I>x</I> </SUB> to CNF precursor ratio. The optimized SnO<SUB> <I>x</I> </SUB>/CNF-based symmetric supercapacitor exhibited a capacitance of 289 F·g<SUP>−1</SUP> at a scan rate of 10 mV·s<SUP>−1</SUP>. Moreover, it retained more than 88% of its initial capacitance after 5000 cycles, highlighting the long-term stability of supercapacitors based on these SnO<SUB> <I>x</I> </SUB>/CNF mats.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A core-shell-structured SnO<SUB>x</SUB>/CNF composite mat electrodes were synthesized by single-nozzle-electrospinning. </LI> <LI> The core-shell composite is highly flexible and freestanding. </LI> <LI> Capacitors using these electrodes had specific capacitance of up to 289 F·g<SUP>−1</SUP> at a scan rate of 10 mV·s<SUP>−1</SUP>. </LI> <LI> Specific capacitance at a current density of 100 mA·g<SUP>−1</SUP> reached 273 F·g<SUP>−1</SUP>. </LI> </UL> </P>

High-performance supercapacitors using flexible and freestanding MnO_x/carbamide carbon nanofibers

Samuel, Edmund,Jo, Hong Seok,Joshi, Bhavana,Park, Hyun Goo,Kim, Yong Il,An, Seongpil,Swihart, Mark T.,Yun, Je Moon,Kim, Kwang Ho,Yoon, Sam S. Elsevier 2017 APPLIED SURFACE SCIENCE - Vol.423 No.-

<P><B>Abstract</B></P> <P>We demonstrate the fabrication of a MnO<I> <SUB>x</SUB> </I>/carbamide carbon nanofiber (CCNF) composite consisting of MnO particles embedded in CCNFs as a highly flexible and freestanding electrode material for supercapacitors. A sacrificial polymer component, polymethylmethacrylate, included in the precursor solution, pyrolyzes during heating, resulting in pores in the fibers, some of which are filled by the MnO nanocrystals. Carbamide is added to control the size of the MnO<I> <SUB>x</SUB> </I> particles as well as to increase the carbon content of the composite and hence its conductivity. The X-ray diffraction and Raman spectra of the composite show that the MnO particles formed have low crystallinity. Transmission electron microscopy confirms that the MnO particles are distributed very uniformly over the CCNFs. Symmetric supercapacitors constructed using electrodes of this composite exhibit specific capacitances of 498F∙g<SUP>−1</SUP> at a scan rate of 10mV∙s<SUP>−1</SUP> and 271F∙g<SUP>−1</SUP> at a current density of 1A∙g<SUP>−1</SUP>. They also exhibit excellent long-term cycling performance, retaining 93% of their initial capacity after 5000 cycles of galvanostatic charging/discharging.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We successfully fabricated a novel flexible MnO/CCNF composite. </LI> <LI> Flexible MnO/CCNF showed excellent retention (93%) after 5000 cycles at 1Ag<SUP>−1</SUP>. </LI> <LI> MnO/CCNF composite demonstrated specific capacitance of 498Fg<SUP>−1</SUP> at a scan rate of 10mVs<SUP>−1</SUP>. </LI> <LI> Dynamic MnO particle formation controlled by using carbamide. </LI> </UL> </P>

팬텀 모델 제작을 위한 SBS / 도전체 / 유전체 3 상 복합재료의 유전특성 연구

김윤진(Yoon Jin Kim),최형도(Hyung Do Choi),조광윤(Kwang Yun Cho),유돈식(Don Sik Yoo),윤호규(Ho Gyu Yoon),서광석(Kwang S . Suh) 한국고분자학회 2001 폴리머 Vol.25 No.1

WCDMA 통신용 I-Q 채널 12비트 1GS/s CMOS DAC

서성욱(Sung-uk Seo),신선화(Sunhwa Shin),주찬양(Chanyang Joo),김수재(Soojae Kim),윤광섭(Kwang S. Yoon) 대한전자공학회 2008 電子工學會論文誌-SD (Semiconductor and devices) Vol.45 No.1

본 논문에서는 WCDMA 통신용 송신기에 적용 가능한 12비트 1GS/s 전류구동 방식의 혼합형 DAC를 설계하였다. 제안된 DAC는 혼합형 구조로써 하위 4비트는 이진 가중치 구조, 중간비트와 상위비트는 4비트 온도계 디코더 구조로 12비트를 구성하였다. 제안된 DAC는 혼합형 구조에서 발생되는 지연시간에 따른 성능 저하를 개선하기 위해 지연시간보정 회로를 사용하였다. 지연시간보정 회로는 위상주파수 검출기, 전하펌프, 제어회로로 구성되어 이진 가중치 구조와 온도계 디코더 구조에서 발생하는 지연시간을 감소시킨다. 제안한 DAC는 CMOS 0.18㎛ 1-poly 6-metal n-well 공정을 사용하여 제작되었고 측정된 INL/DNL은 ±0.93LS/ 0.62LSB 이하로 나타났다. 입력 주파수 1㎑에서 SFDR은 약 60㏈로 측정되었고, SNDR은 51㏈로 측정되었다. 단일 DAC의 전력소모는 46.2mW로 나타났다. This paper describes a 12 bit 1GS/s current mode segmented DAC for WCDMA communication. The proposed circuit in this paper employes segmented structure which consists of 4bit binary weighted structure in the LSB, and 4bit thermometer decoder structure in the mSB and MSB. The proposed DAC uses delay time compensation circuits in order to suppress performance decline by delay time in segmented structure. The delay time compensation circuit comprises of phase frequency detector, charge pump, and control circuits, so that suppress delay time by binary weighted structure and thermometer decoder structure. The proposed DAC uses CMOS 0.18㎛ 1-poly 6-metal n-well process, and measured INL/DNL are below ±0.93LSB/±0.62LSB. SFDR is approximately 60dB and SNDR is 51dB at 1㎑ input frequency. Single DAC's power consumption is 46.2mW.

Intramolecular deformation of zeotype-borogermanate toward a three-dimensional porous germanium anode for high-rate lithium storage

Yoon, Taeseung,Song, Gyujin,Harzandi, Ahmad M.,Ha, Miran,Choi, Sungho,Shadman, Sahar,Ryu, Jaegeon,Bok, Taesoo,Park, Soojin,Kim, Kwang S. The Royal Society of Chemistry 2018 Journal of Materials Chemistry A Vol.6 No.33

<P>We demonstrate a new class of synthetic process for three-dimensional porous Ge materials (3D-pGe). Starting from zeotype-borogermanate microcubes, the 3D-pGe sample was synthesized through a thermal deformation of artificial Ge-rich zeolite, etching, and subsequent hydrogen reduction. After the synthesis, the resultant byproducts were simply removed by warm water instead of a harmful etchant such as hydrofluoric acid. Benefiting from the structural advantages with meso/macro porosity in the overall framework, the as-prepared 3D-pGe exhibits good electrochemical properties as anode materials for lithium-ion batteries with a high capacity (770 mA h g<SUP>−1</SUP>), cycling stability (capacity retention over 83%) after 250 cycles at 1C, and excellent rate capability (32% for 10C with respect to C/5) as well as pseudocapacitive contribution by surface-controlled reaction. This study paves the way to a new synthesis strategy of 3D porous Ge anode materials from zeolite for large-scale energy storage applications.</P>