http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Lee, Seunghwa,Yeom, Ji-Hyun,Seo, Sojin,Lee, Minho,Kim, Sarang,Bae, Jeehyeon,Lee, Kangseok,Hwang, Jihwan Microbiological Society of Korea 2015 The journal of microbiology Vol.53 No.4
<P>Resistance-nodulation-division (RND) efflux pumps are associated with multidrug resistance in many gram-negative pathogens. The genome of Vibrio vulnificus encodes 11 putative RND pumps homologous to those of Vibrio cholerae and Escherichia coli. In this study, we analyzed three putative RND efflux pumps, showing homology to V. cholerae VexAB and VexCD and to E. coli AcrAB, for their functional roles in multidrug resistance of V. vulnificus. Deletion of the vexAB homolog resulted in increased susceptibility of V. vulnificus to bile acid, acriflavine, ethidium bromide, and erythromycin, whereas deletion of acrAB homologs rendered V. vulnificus more susceptible to acriflavine only. Deletion of vexCD had no effect on susceptibility of V. vulnificus to these chemicals. Upon exposure to these antibacterial chemicals, expression of tolCV1 and tolCV2, which are putative outer membrane factors of RND efflux pumps, was induced, whereas expression levels of vexAB, vexCD, and acrAB homologs were not significantly changed. Our results show that the V. vulnificus homologs of VexAB largely contributed to in vitro antimicrobial resistance with a broad substrate specificity that was partially redundant with the AcrAB pump homologs.</P>
Electrocatalytic Reduction of Gas-Phased CO<sub>2</sub> on Nano-Sized Sn Electrode Surface
Lee, Seunghwa,Ju, HyungKuk,Jeon, Hongrae,Machunda, Revocatus L,Kim, Dahee,Lee, Jae Kwang,Lee, Jaeyoung The Electrochemical Society 2013 ECS transactions Vol.53 No.29
<P>Electrochemical conversion of CO<SUB>2 </SUB>(ECC) is one of the promising approaches which may produce alternative organic chemicals such as HCOOH, CH<SUB>3</SUB>OH and C<SUB>2</SUB>H<SUB>4</SUB>. Use of efficient catalysts and systems are necessarily required to obtain high selectivity and high conversion rate. In this study, nano-sized Sn electrocatalyst for producing formic acid is sprayed onto the gas diffusion electrode and a zero-gap electrolytic cell with the membrane electrode assembly is applied. A constant production of formic acid analyzed by UV-spectroscopy is obtained.</P>
Lee, Seunghwa,Ocon, Joey D.,Son, Young-il,Lee, Jaeyoung American Chemical Society 2015 The Journal of Physical Chemistry Part C Vol.119 No.9
<P>Electrolyte pH is an important parameter in determining the equilibrium concentrations of the carbon dioxidebicarbonatecarbonate system as well as in mapping out the thermodynamically stable phases of tin dioxide (SnO2) in an aqueous electrochemical system. Thus, we explored an optimized region in the combined potentialpH (EpH) diagram of the two systems where there is a simultaneously high catalytic activity for carbon dioxide (CO2) electrolysis and good phase stability for the SnO2 nanocatalysts. Our results suggest that choosing the right EpH combination, which in this case is at -0.6 V (vs RHE) and pH 10.2, results in a high faradaic efficiency of 67.6% for formate (HCOO) synthesis and an efficiency retention of similar to 90% after 5 h while maintaining the stability of the oxide structure and avoiding the formation of carbon monoxide. Widely applicable to neutral or near-neutral pH metal oxide electrocatalysts, optimized alkaline CO2 electrolysis offers distinct advantages in terms of the three major catalyst properties: activity, selectivity, and stability.</P>
Lee, Seunghwa,Kim, Dahee,Lee, Jaeyoung WILEY‐VCH Verlag 2015 Angewandte Chemie Vol.54 No.49
<P><B>Abstract</B></P><P>Electrocatalytic conversion of carbon dioxide (CO<SUB>2</SUB>) has recently received considerable attention as one of the most feasible CO<SUB>2</SUB> utilization techniques. In particular, copper and copper‐derived catalysts have exhibited the ability to produce a number of organic molecules from CO<SUB>2</SUB>. Herein, we report a chloride (Cl)‐induced bi‐phasic cuprous oxide (Cu<SUB>2</SUB>O) and metallic copper (Cu) electrode (Cu<SUB>2</SUB>O<SUB>Cl</SUB>) as an efficient catalyst for the formation of high‐carbon organic molecules by CO<SUB>2</SUB> conversion, and identify the origin of electroselectivity toward the formation of high‐carbon organic compounds. The Cu<SUB>2</SUB>O<SUB>Cl</SUB> electrocatalyst results in the preferential formation of multi‐carbon fuels, including <I>n</I>‐propanol and <I>n</I>‐butane C3–C4 compounds. We propose that the remarkable electrocatalytic conversion behavior is due to the favorable affinity between the reaction intermediates and the catalytic surface.</P>
Lee, Seunghwa,Hong, Sujik,Lee, Jaeyoung Elsevier 2017 CATALYSIS TODAY - Vol.288 No.-
<P><B>Abstract</B></P> <P>Controlling product selectivity is regarded as one of the main barriers in the application of Cu-based electrodes to electrochemical CO<SUB>2</SUB> reduction and hence significant studies on experimental factors to improve the selectivity towards desired products. In particular, two pH parameters appear to be important in controlling product selectivity of the CO<SUB>2</SUB> reduction process. We study how both bulk and local pH conditions affect product distributions during CO<SUB>2</SUB> reduction on oxygen-evacuated Cu<SUB>2</SUB>O electrode. In contrast with previous studies of local pH effect on CO<SUB>2</SUB> reduction using metallic Cu, our results suggest that not always is the preferential production of C2 compounds (C<SUB>2</SUB>H<SUB>4</SUB> +C<SUB>2</SUB>H<SUB>6</SUB>) achieved by high local pH condition irrespective of catalyst materials, but rather bulk pH condition could contribute to ability to control product selectivity. It is finally demonstrated that the bulk pH effect, often underestimated but related to carbonate speciation, is associated with the direct reduction of HCO<SUB>3</SUB> <SUP>−</SUP> to HCOO<SUP>−</SUP>.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Electrocatalytic reduction of CO<SUB>2</SUB> on oxygen-evacuated Cu<SUB>2</SUB>O. </LI> <LI> Controlling production of CO and HCOO<SUP>−</SUP> <I>via</I> different bulk pH contribution. </LI> <LI> Prioritizing bulk and local pH effect on product selectivity. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>While the electrochemical reduction of CO<SUB>2</SUB> into C2 compounds on Cu metal was selectively achieved by higher local pH condition, the local pH effect became less important in the CO<SUB>2</SUB> reduction on the oxygen-evacuated Cu<SUB>2</SUB>O. Instead, on the oxygen-evacuated Cu<SUB>2</SUB>O, we demonstrate that changing the bulk pH condition could influence on product selectivity and the bulk pH effect is derived from the molar fraction of HCO<SUB>3</SUB> <SUP>−</SUP> with its direct reduction to HCOO<SUP>−</SUP>.</P> <P>[DISPLAY OMISSION]</P>