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Ribosomally Synthesiszed Antimicrobial Peptides (Bacteriocins) in Lactic Acid Bacteria
Ingolf F. Nes,Sung-Sik Yoon,Dzung B. Diep 한국식품과학회 2007 Food Science and Biotechnology Vol.16 No.5
Bacteriocins in Gram-positive bacteria have attracted much attention because many have a strong antimicrobial activity also against bacteria outside the genera of the producers. Lantibiotics and the pediocin-like bactericins have attracted most attention since they kill a broad spectrum of Gram-positive bacteria including important pathogens. But many other promising Gram-positive bacteriocins have been thoroughly characterized. Recent studies have shown that bacteriocins may play a role in the intestinal flora to protect us against the food-borne pathogens. Bacterial genome sequencing has demonstrated that there may be an arsenal of such compounds and we are only seeing the top of the iceberg. The present review gives a short outlook of the field of bacteriocins with focus on lactic acid bacteria and includes recent findings.
Layer-by-Layer Doping of Few-Layer Graphene Film
Gü,neş,, Fethullah,Shin, Hyeon-Jin,Biswas, Chandan,Han, Gang Hee,Kim, Eun Sung,Chae, Seung Jin,Choi, Jae-Young,Lee, Young Hee American Chemical Society 2010 ACS NANO Vol.4 No.8
<P>We propose a new method of layer-by-layer (LbL) doping of thin graphene films. Large area monolayer graphene was synthesized on Cu foil by using the chemical vapor deposition method. Each layer was transferred on a polyethylene terephthalate substrate followed by a salt-solution casting, where the whole process was repeated several times to get LbL-doped thin layers. With this method, sheet resistance was significantly decreased up to ∼80% with little sacrifice in transmittance. Unlike samples fabricated by topmost layer doping, our sample shows better environmental stability due to the presence of dominant neutral Au atoms on the surface which was confirmed by angle-resolved X-ray photoelectron spectroscopy. The sheet resistance of the LbL-doped four-layer graphene (11 × 11 cm<SUP>2</SUP>) was 54 Ω/sq at 85% transmittance, which meets the technical target for industrial applications.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2010/ancac3.2010.4.issue-8/nn1008808/production/images/medium/nn-2010-008808_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn1008808'>ACS Electronic Supporting Info</A></P>
Diffusion Mechanism of Lithium Ion through Basal Plane of Layered Graphene
Yao, Fei,Gü,neş,, Fethullah,Ta, Huy Quang,Lee, Seung Mi,Chae, Seung Jin,Sheem, Kyeu Yoon,Cojocaru, Costel Sorin,Xie, Si Shen,Lee, Young Hee American Chemical Society 2012 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.134 No.20
<P>Coexistence of both edge plane and basal plane in graphite often hinders the understanding of lithium ion diffusion mechanism. In this report, two types of graphene samples were prepared by chemical vapor deposition (CVD): (i) well-defined basal plane graphene grown on Cu foil and (ii) edge plane-enriched graphene layers grown on Ni film. Electrochemical performance of the graphene electrode can be split into two regimes depending on the number of graphene layers: (i) the corrosion-dominant regime and (ii) the lithiation-dominant regime. Li ion diffusion perpendicular to the basal plane of graphene is facilitated by defects, whereas diffusion parallel to the plane is limited by the steric hindrance that originates from aggregated Li ions adsorbed on the abundant defect sites. The critical layer thickness (<I>l</I><SUB>c</SUB>) to effectively prohibit substrate reaction using CVD-grown graphene layers was predicted to be ∼6 layers, independent of defect population. Our density functional theory calculations demonstrate that divacancies and higher order defects have reasonable diffusion barrier heights allowing lithium diffusion through the basal plane but neither monovacancies nor Stone-Wales defect.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2012/jacsat.2012.134.issue-20/ja301586m/production/images/medium/ja-2012-01586m_0003.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja301586m'>ACS Electronic Supporting Info</A></P>
Negative and Positive Persistent Photoconductance in Graphene
Biswas, Chandan,Gü,neş,, Fethullah,Loc, Duong Dinh,Lim, Seong Chu,Jeong, Mun Seok,Pribat, Didier,Lee, Young Hee American Chemical Society 2011 NANO LETTERS Vol.11 No.11
<P>Persistent photoconductance, a prolonged light-induced conducting behavior that lasts several hundred seconds, has been observed in semiconductors. Here we report persistent negative photoconductance and consecutive prominent persistent positive photoconductance in graphene. Unusually large yields of negative PC (34%) and positive PC (1652%) and remarkably long negative transient response time (several hours) were observed. Such high yields were reduced in multilayer graphene and were quenched under vacuum conditions. Two-dimensional metallic graphene strongly interacts with environment and/or substrate, causing this phenomenon, which is markedly different from that in three-dimensional semiconductors and nanoparticles.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/nalefd/2011/nalefd.2011.11.issue-11/nl202266h/production/images/medium/nl-2011-02266h_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nl202266h'>ACS Electronic Supporting Info</A></P>
Influence of Copper Morphology in Forming Nucleation Seeds for Graphene Growth
Han, Gang Hee,Gü,neş,, Fethullah,Bae, Jung Jun,Kim, Eun Sung,Chae, Seung Jin,Shin, Hyeon-Jin,Choi, Jae-Young,Pribat, Didier,Lee, Young Hee American Chemical Society 2011 NANO LETTERS Vol.11 No.10
<P>We report that highly crystalline graphene can be obtained from well-controlled surface morphology of the copper substrate. Flat copper surface was prepared by using a chemical mechanical polishing method. At early growth stage, the density of graphene nucleation seeds from polished Cu film was much lower and the domain sizes of graphene flakes were larger than those from unpolished Cu film. At later growth stage, these domains were stitched together to form monolayer graphene, where the orientation of each domain crystal was unexpectedly not much different from each other. We also found that grain boundaries and intentionally formed scratched area play an important role for nucleation seeds. Although the best monolayer graphene was grown from polished Cu with a low sheet resistance of 260 Ω/sq, a small portion of multilayers were also formed near the impurity particles or locally protruded parts.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/nalefd/2011/nalefd.2011.11.issue-10/nl201980p/production/images/medium/nl-2011-01980p_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nl201980p'>ACS Electronic Supporting Info</A></P>
Miguel Rojas,Se, bastien Desche,nes,Philip Merrigan KINFORMS 2019 Management Review Vol.14 No.2
This article investigates if reforms of financial markets in Costa Rica have reduced the concentration of the financial industry and the interest-rate spread, two desirable outcomes of financial reforms. Our investigation shows that the concentration of the financial industry, measured by the Herfindhal-Hirschman index, fell notably after the conclusion of the reforms, suggesting an increased competition among financial institutions. Our research, however, does not support the view that the fall in concentration led to a reduction in the interest-rate spread. We provide explanations for the results and suggest avenues for future research.
Mobilization Functions of the Bacteriocinogenic Plasmid pRJ6 of Staphylococcus aureus
Marcus Lívio Varella Coelho,Hilana Ceotto,Danielle Jannuzzi Madureira,Ingolf F. Nes,Maria do Carmo de Freire Bastos 한국미생물학회 2009 The journal of microbiology Vol.47 No.3
Plasmid pRJ6 is the first known bacteriocinogenic mobilizable (Mob) plasmid of Staphylococcus aureus. Its Mob region is composed of four mob genes (mobCDAB) arranged as an operon, a genetic organization uncommon among S. aureus Mob plasmids. oriTpRJ6 was detected in a region of 431 bp, positioned immediately upstream of mobC. This region, when cloned into pCN37, was able to confer mobilization to the recombinant plasmid only in the presence of pRJ6. The entire Mob region, including oriTpRJ6, is much more similar to Mob regions from several coagulase-negative staphylococci plasmids, although some remarkable similarities with S. aureus Mob plasmids can also be noted. These similarities include the presence within oriTpRJ6 of the three mcb (MobC binding sites), firstly described in pC221 and pC223, an identical nick site also found in these same plasmids, and a nearly identical srapC223 site (sequence recognized by MobA). pRJ6 was successfully transferred to S. epidermidis by conjugation in the presence of the conjugative plasmid pGO1. Altogether these findings suggest that pRJ6 might have been originally a coagulase-negative staphylococci plasmid that had been transferred successfully to S. aureus.
Laser Thinning for Monolayer Graphene Formation: Heat Sink and Interference Effect
Han, Gang Hee,Chae, Seung Jin,Kim, Eun Sung,Gü,neş,, Fethullah,Lee, Il Ha,Lee, Sang Won,Lee, Si Young,Lim, Seong Chu,Jeong, Hae Kyung,Jeong, Mun Seok,Lee, Young Hee American Chemical Society 2011 ACS NANO Vol.5 No.1
<P>Despite the availability of large-area graphene synthesized by chemical vapor deposition (CVD), the control of a uniform monolayer graphene remained challenging. Here, we report a method of acquiring monolayer graphene by laser irradiation. The accumulation of heat on graphene by absorbing light, followed by oxidative burning of upper graphene layers, which strongly relies on the wavelength of light and optical parameters of the substrate, was <I>in situ</I> measured by the G-band shift in Raman spectroscopy. The substrate plays a crucial role as a heat sink for the bottom monolayer graphene, resulting in no burning or etching. Oscillatory thinning behavior dependent on the substrate oxide thickness was evaluated by adopting a simple Fresnel’s equation. This paves the way for future research in utilizing monolayer graphene for high-speed electronic devices.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2011/ancac3.2011.5.issue-1/nn1026438/production/images/medium/nn-2010-026438_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn1026438'>ACS Electronic Supporting Info</A></P>
Choirs, H I galaxy groups: catalogue and detection of star-forming dwarf group members
Sweet, S. M.,Meurer, G.,Drinkwater, M. J.,Kilborn, V.,Dé,nes, H.,Bekki, K.,Hanish, D.,Ferguson, H.,Knezek, P.,Bland-Hawthorn, J. Oxford University Press 2013 Monthly notices of the Royal Astronomical Society Vol.433 No.1