Highly Efficient Electrochemical Responses on Single Crystalline Ruthenium–Vanadium Mixed Metal Oxide Nanowires

Chun, Sung Hee,Choi, Hyun-A,Kang, Minkyung,Koh, Moonjee,Lee, Nam-Suk,Lee, Sang Cheol,Lee, Minyung,Lee, Youngmi,Lee, Chongmok,Kim, Myung Hwa American Chemical Society 2013 ACS APPLIED MATERIALS & INTERFACES Vol.5 No.17

<P>Highly efficient single crystalline ruthenium–vanadium mixed metal oxide (Ru<SUB>1–<I>x</I></SUB>V<SUB><I>x</I></SUB>O<SUB>2</SUB>, 0 ≤ <I>x</I> ≤ 1) nanowires were prepared on a SiO<SUB>2</SUB> substrate and a commercial Au microelectrode for the first time through a vapor-phase transport process by adjusting the mixing ratios of RuO<SUB>2</SUB> and VO<SUB>2</SUB> precursors. Single crystalline Ru<SUB>1–<I>x</I></SUB>V<SUB><I>x</I></SUB>O<SUB>2</SUB> nanowires show homogeneous solid-solution characteristics as well as the distinct feature of having remarkably narrow dimensional distributions. The electrochemical observations of a Ru<SUB>1–<I>x</I></SUB>V<SUB><I>x</I></SUB>O<SUB>2</SUB> (<I>x</I> = 0.28 and 0.66)-decorated Au microelectrode using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) demonstrate favorable charge-transfer kinetics of [Fe(CN)<SUB>6</SUB>]<SUP>3–/4–</SUP> and Ru(NH<SUB>3</SUB>)<SUB>6</SUB><SUP>3+/2+</SUP> couples compared to that of a bare Au microelectrode. The catalytic activity of Ru<SUB>1–<I>x</I></SUB>V<SUB><I>x</I></SUB>O<SUB>2</SUB> for oxygen and H<SUB>2</SUB>O<SUB>2</SUB> reduction at neutral pH increases as the fraction of vanadium increases within our experimental conditions, which might be useful in the area of biofuel cells and biosensors.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2013/aamick.2013.5.issue-17/am4016445/production/images/medium/am-2013-016445_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am4016445'>ACS Electronic Supporting Info</A></P>

Studies of Small Molecule Dyes that Interact with Pyrene-labeled Amyloid Fragments

Lee, Hyemin,Lee, Hwiin,Lee, Minyung Korean Chemical Society 2014 Bulletin of the Korean Chemical Society Vol.35 No.11

Volume Increment Effect on the Photoisomerization of Hemicyanine Dyes in Oligo(ethylene glycol)s

Lee, Youmin,Lee, Minyung American Chemical Society 2013 The journal of physical chemistry. A, Molecules, s Vol.117 No.48

<P>We studied the excited-state dynamics of three hemicyanine dyes that undergo internal twisting from the localized excited state to the twisted intramolecular charge-transfer state. The dyes differ in the length of the alkyl chain in the aniline moiety and, thus, the volume of the motional moiety increases without having much of an effect on the excited-state potential surface. By employing oligo(ethylene glycol)s as a new homologous series of solvents that covers a high viscosity region, we showed that the excited-state lifetime of the hemicyanines gradually increases at any given viscosity when the size of the substituent increases. We describe our results for the solution-phase photoisomerization processes in terms of the breakdown of Stokes’ law, multidimensionality, and the Hubbard relation.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpcafh/2013/jpcafh.2013.117.issue-48/jp4101043/production/images/medium/jp-2013-101043_0008.gif'></P>

Excluded Volume Effect in the Fluorescence Energy Transfer of Single Donor–Multiple Acceptors in Polymer

Lee, Hyemin,Lee, Minyung American Chemical Society 2012 The Journal of physical chemistry B Vol.116 No.39

<P>Fluorescence resonance energy transfer (FRET) from a donor to multiple acceptors is an interesting subject. Numerous studies using theoretical models and simulations have focused on the excluded volume effect, which was not considered in Förster’s first derivation. In this work, we first present the experimental results on the excluded volume effect by employing time-resolved FRET. Coumarin 334 (C334) was used as the energy donor whereas hemin and cytochrome <I>c</I> (cyt <I>c</I>) were used as the energy acceptors. The fluorescence intensity decays were measured for C334 surrounded by a number of acceptors in poly(acrylic acid). We have observed that the excluded volume effect is markedly pronounced with cyt <I>c</I> compared with hemin when the acceptor concentration is high (>5 mM). The results, which may be explicitly described by the relative molecular sizes of two acceptors, showed that the excluded volume effect should be considered in the interpretation of FRET data, especially when bulk chromophores are used.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpcbfk/2012/jpcbfk.2012.116.issue-39/jp306164a/production/images/medium/jp-2012-06164a_0009.gif'></P>

Elucidation of photo-induced electron transfer in a loop-forming peptide: Dye-Ala-Gly-Gln-Tyr

Lee, Hwiin,Kim, Jeongyun,Kwon, Yong-Uk,Lee, Minyung Korean Society of Photoscience 2015 Rapid communication in photoscience Vol.4 No.3

We investigated photo-induced electron transfer (PET) in a dye-labeled peptide, fluorophore-Ala-Gly-Gln-Tyr, employing time-resolved fluorescence. As an effort to develop new functional dyes, we studied an acriflavine derivative for the electron-acceptor in the excited state from tyrosine, an electrondonor in the ground-state. The pH dependence of the fluorescence lifetime of the model peptide indicates that electron transfer between the excited dye and tyrosine occurs when the tyrosine is deprotonated. The proton-coupled electron transfer appears to be sequential rather than concerted. We also report direct time measurements on the end-to-end loop formation processes of the peptide in water.

Estimation of multiexponential fluorescence decay parameters using compressive sensing

Yang, Sejung,Lee, Joohyun,Lee, Youmin,Lee, Minyung,Lee, Byung-Uk SPIE - International Society for Optical Engineeri 2015 Journal of biomedical optics Vol.20 No.9

Photoionization of N,N,N',N'-Tetramethyl-p-phenylenediamine in Polar Solvents

Min Yeong Lee,Du Jeon Jang,Minyung Lee,Du-Jeon Jang,Dongho Kim,Sun Sook Lee,Bong Hyun Boo Korean Chemical Society 1991 Bulletin of the Korean Chemical Society Vol.12 No.4

The photoinduced electron transfer reactions of N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) in various polar solvents were studied by measuring time-resolved fluorescence. The temperature dependence on the fluorescence decay rate in acetonitrile, methanol, ethanol and buthanol was carried out to obtain the activation energy and Arrehnius factor for the photoinduced electron transfer reaction. It was found that as the dielectric constant of the solvent increases, the activation energy and the reaction rate increase. This implys that the Arrehnius factor is important in controlling the photoinduced electron transfer reaction rate. In water, TMPD exists in three forms (cationic, protonated and neutral forms) due to the high dielectric constant and strong proton donating power of water. The photoinduced electron transfer reaction was found to be very fast (< 50 ps) and also the long liverd component in the fluorescence decay profile attributable to the photoexcited protonated form of TMPD was observed. Probably, the reaction pathway and the reaction coordinate seem to be different depending on the solvents studied here.

GIS를 이용한 유출시뮬레이션에 관한 연구

김민영,지홍기,이순탁 嶺南大學校 環境問題硏究所 1999 環境硏究 Vol.19 No.1

요약문 본 연구에서는 기존의 재래적인 방법에 의해 모의된 수문곡성과 GIS를 이용한 자료를 바탕 으로 모의된 수문곡선을 실제 수문곡선과 비교함으로써 수문학에 있어서 GIS의 적용성을 검토할 뿐만 아니라, 이에 따른 결과를 바탕으로 두 방법을 통한 지형인자산출의 비교를 통 해 탱크모델의 매개 변수와의 상관관계를 분석하였다. 강우-유출 모델에 있어서 모델을 개발하거나 하나의 모델을 선정하는데는 사용목적의 적합 성, 구조의 단순성, 사용의 용이성 및 최소한의 입력자료 등을 생각하여 결정할 필요가 있 다. 이러한 점에서 본 연구에서는 다른 모델들에 비해 유출량을 추정하는데 있어서 구조의 단순성과 적은 양의 입력자료가 요구되는 점에서 탱크모델을 선정하여 IHP대표시험유역인 위천유역에 적용하였다. Abstract In this study, application of in runoff simulation is examined through the comparison of hydrographs which are simulated by classical method from GIS based data with actual hydrograph, and correlarion with parameters of tank model is analyzed through comparison of physiographic factors by two methods above on the base of the results. It is necessary to consider the compatability of purpose, the simplicity of structure, the convenience of usage, and minimum input data for developing a new model or selecting one model among various rainfall-runoff models. Based on this idea, this study selectstank model for it requires simpler structure and input data than dther models in estimation of runoff capacity and applies it to Wichun basin which is the representative area of IHP.

초소수성 표면을 이용한 하이드로젤 중공 캡슐 제조

송민영(Minyung Song),이지영(Jiyoung Lee),서경덕(Kyung Duck Seo),김동성(Dong Sung Kim),장석태(Suk Tai Chang) 한국고분자학회 2016 폴리머 Vol.40 No.5

초소수성 표면을 이용하여 간단하고 빠르게 하이드로젤 중공 캡슐을 제작하는 새로운 방법을 개발하였다. 광개시제를 포함하는 탄화수소 오일 층에 초소수성 성질을 가지는 기판을 위치시키고, 하이드로젤 단량체와 가교제를 함유한 마이크로 리터 부피의 droplet을 초소수성 표면에 형성하였다. UV light를 초소수성 표면에 조사하여 droplet의 물과 오일 계면에서 광개시제의 확산으로 일어난 광중합반응을 통해 형성된 하이드로젤 중공 캡슐을 제조하였다. 이러한 간단하고 효과적인 초소수성 표면 위에서 하이드로젤 중공 캡슐을 제작하는 방법은 콜로이드 나노 입자, 약물, 또는 세포 등을 쉽게 캡슐화하는데 활용될 것으로 전망된다. A single-step synthetic method for preparing hydrogel hollow capsules on a superhydrophobic surface was successfully developed. Aqueous microdroplets of a mixture of hydrogel monomer and cross-linker solutions were deposited on the superhydrophobic surface, which was situated under the hydrocarbon oil layer containing photoinitiator. When exposed to UV light, the aqueous microdroplets were converted to hollow capsules with a polymerized hydrogel shell, formed due to the diffusion of photoinitiators at the oil/water interface. This method for producing hydrogel hollow capsules on superhydrophobic surfaces is simple and efficient, rendering easy encapsulation of colloidal nanoparticles, drugs, or biological cells.

Excited-State Dynamics of Bis(9-fluorenyl)methane and its Derivative 9-(9-Ethylfluorenyl)-9′-fluorenylmethane: Steric Effect on Energetics and Dynamics of Ground- and Excited-State Conformations

Boo, Bong Hyun,Lee, Minyung,Jeon, Ki-Seok,Kim, Seung-Joon American Chemical Society 2014 The Journal of physical chemistry A Vol.118 No.12

<P>Intramolecular excimer formation of bis(9-fluorenyl)methane (BFM) and 9-(9′-ethylfluorenyl)-9-fluorenylmethane (EFFM), in which an ethyl group is substituted to a 9-H atom in BFM, was studied by means of steady-state and time-resolved fluorescence. Ab initio and DFT calculations enabled the prediction of three conformers as stable species of orthogonal, trans–gauche, and gauche–gauche. The theoretical and experimental results reveal that the substitution effect is also found to appreciably influence the energies, spectroscopy, and kinetics associated with the interconversion of various conformers of the diaryl compounds. We have not observed the rising components in the excimer fluorescence decay of BFM and EFFM in PMMA as observed in the liquid solutions probably because of the existence of the sandwich conformer responsible for the excimer fluorescence prior to the laser irradiation.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpcafh/2014/jpcafh.2014.118.issue-12/jp411878r/production/images/medium/jp-2013-11878r_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp411878r'>ACS Electronic Supporting Info</A></P>