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- 저자 : Zhe-Wei Lee (검색결과 4 건)
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Sun, Zhe,Lee, Sangsu,Park, Kyu Hyung,Zhu, Xiaojian,Zhang, Wenhua,Zheng, Bin,Hu, Pan,Zeng, Zebing,Das, Soumyajit,Li, Yuan,Chi, Chunyan,Li, Run-Wei,Huang, Kuo-Wei,Ding, Jun,Kim, Dongho,Wu, Jishan American Chemical Society 2013 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.135 No.48
<P><I>Clar’s aromatic sextet rule</I> has been widely used for the prediction of the reactivity and stability of polycyclic aromatic hydrocarbons with a <I>closed-shell</I> electronic configuration. Recent advances in <I>open-shell</I> biradicaloids have shown that the number of aromatic sextet rings plays an important role in determination of their ground states. In order to test the validity of this rule in singlet biradicaloids, the two soluble and stable dibenzoheptazethrene isomers <B>DBHZ1</B> and <B>DBHZ2</B> were prepared by different synthetic approaches and isolated in crystalline form. These two molecules have different numbers of aromatic sextet rings in their respective biradical resonance forms and thus are expected to exhibit varied singlet biradical character. This assumption was verified by different experimental methods, including nuclear magnetic resonance (NMR), electron spin resonance (ESR), superconducting quantum interference device (SQUID), steady-state and transient absorption spectroscopy (TA), and X-ray crystallographic analysis, assisted by unrestricted symmetry-broken density functional theory (DFT) calculations. <B>DBHZ2</B>, with more aromatic sextet rings in the biradical form, was demonstrated to possess greater biradical character than <B>DBHZ1</B>; as a result, <B>DBHZ2</B> exhibited an intense one-photon absorption (OPA) in the near-infrared region (λ<SUB>abs</SUB><SUP>max</SUP> <I>=</I> 804 nm) and a large two-photon absorption (TPA) cross-section (σ<SUP>(2)</SUP><SUB>max</SUB> = 2800 GM at 1600 nm). This investigation together with previous studies indicates that Clar’s aromatic sextet rule can be further extended to the singlet biradicaloids to predict their ground states and singlet biradical characters.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2013/jacsat.2013.135.issue-48/ja410279j/production/images/medium/ja-2013-10279j_0012.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja410279j'>ACS Electronic Supporting Info</A></P>
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Te-Hua Fang,Zhe-Wei Lee,Win-Jin Chang 한국물리학회 2017 Current Applied Physics Vol.17 No.10
We perform molecular dynamics (MD) simulations to study the structural response and fracture characteristics of nanoporous graphene (NPG) membranes subjected to shear loading. The effects of porosity, temperature, and shear velocity on the mechanical responses of NPG membranes are examined. The results show that the wrinkling of the membrane becomes more obvious with increasing strain. Fractures occur around holes on the long diagonal of the NPG parallelogram, and fracture stress in the NPG membrane decreases with increasing porosity. In addition, the effect of shear velocity on the shear modulus decreases with increasing porosity. The fracture strain of NPG membranes with different porosities obviously decreases with increasing temperature. The results enhance our understanding of the shear mechanical properties of NPG membranes and are helpful for the design and application of highperformance NPG membranes.
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Flavobacterium dongtanense sp. nov., isolated from the rhizosphere of a wetland reed.
Xiao, Yi-Ping,Hui, Wei,Lee, Jung-Sook,Lee, Keun Chul,Quan, Zhe-Xue Society for General Microbiology 2011 International journal of systematic and evolutiona Vol.61 No.2
<P>Two strains of Gram-reaction-negative, rod-shaped, non-spore-forming, non-motile, aerobic bacteria, designated LW30(T) and LW29, were isolated from the rhizosphere of a wetland reed in Dongtan, Chongming Island, China. The strains formed pale-yellow colonies on R2A plates. Growth occurred at 4-37 C (optimum 30 C), at pH 6-9 (optimum pH 7-8) and in the presence of 0-3?% (w/v) NaCl (optimum 0-1?%). Oxidase and catalase activities and flexirubin-type pigments were absent. MK-6 was the major respiratory quinone. The major fatty acids were iso-C(15?:?0), C(15?:?0), iso-C(15?:?1) G and iso-C(17?:?1)ω9c. Strains LW30(T) and LW29 could be differentiated from related species by several phenotypic characteristics. Phylogenetic analyses based on 16S rRNA gene sequences placed strains LW30(T) and LW29 in the genus Flavobacterium with high sequence similarity to Flavobacterium cheniae NJ-26(T) (94.0?%) and Flavobacterium indicium GPTSA 100-9(T) (93.9?%). Together with F. indicium GPTSA 100-9(T), strains LW30(T) and LW29 formed a distinct group in the phylogenetic tree. The DNA G+C content was 30 mol%. On the basis of the phylogenetic and phenotypic evidence, strains LW30(T) and LW29 represent a novel species of the genus Flavobacterium, for which the name Flavobacterium dongtanense sp. nov. is proposed. The type strain is LW30(T) (=KCTC 22671(T) =CCTCC AB 209201(T)).</P>
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Li, Yuan,Heng, Wee-Kuan,Lee, Byung Sun,Aratani, Naoki,Zafra, José,L.,Bao, Nina,Lee, Richmond,Sung, Young Mo,Sun, Zhe,Huang, Kuo-Wei,Webster, Richard D.,Ló,pez Navarrete, Juan T.,Kim, Dongh American Chemical Society 2012 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.134 No.36
<P>Polycyclic aromatic hydrocarbons with an open-shell singlet biradical ground state are of fundamental interest and have potential applications in materials science. However, the inherent high reactivity makes their synthesis and characterization very challenging. In this work, a convenient synthetic route was developed to synthesize two kinetically blocked heptazethrene (<B>HZ-TIPS</B>) and octazethrene (<B>OZ-TIPS</B>) compounds with good stability. Their ground-state electronic structures were systematically investigated by a combination of different experimental methods, including steady-state and transient absorption spectroscopy, variable temperature NMR, electron spin resonance (ESR), superconducting quantum interfering device (SQUID), FT Raman, and X-ray crystallographic analysis, assisted by unrestricted symmetry-broken density functional theory (DFT) calculations. All these demonstrated that the heptazethrene derivative <B>HZ-TIPS</B> has a closed-shell ground state while its octazethrene analogue <B>OZ-TIPS</B> with a smaller energy gap exists as an open-shell singlet biradical with a large measured biradical character (<I>y</I> = 0.56). Large two-photon absorption (TPA) cross sections (σ<SUP>(2)</SUP>) were determined for <B>HZ-TIPS</B> (σ<SUP>(2)</SUP><SUB>max</SUB> = 920 GM at 1250 nm) and <B>OZ-TIPS</B> (σ<SUP>(2)</SUP><SUB>max</SUB> = 1200 GM at 1250 nm). In addition, <B>HZ-TIPS</B> and <B>OZ-TIPS</B> show a closely stacked 1D polymer chain in single crystals.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2012/jacsat.2012.134.issue-36/ja304618v/production/images/medium/ja-2012-04618v_0015.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja304618v'>ACS Electronic Supporting Info</A></P>
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