Sungkyunkwan University

About: Sungkyunkwan University is a education organization based out in Seoul, South Korea. It is known for research contribution in the topics: Graphene & Thin film. The organization has 28229 authors who have published 56428 publications receiving 1352733 citations. The organization is also known as: 성균관대학교.

RPA governs endonuclease switching during processing of Okazaki fragments in eukaryotes

Abstract: Extensive work on the maturation of lagging strands during the replication of simian virus 40 DNA suggests that the initiator RNA primers of Okazaki fragments are removed by the combined action of two nucleases, RNase HI and Fen1, before the Okazaki fragments join1,2,3,4,5 Despite the well established in vitro roles of these two enzymes6, genetic analyses in yeast revealed that null mutants of RNase HI and/or Fen1 are not lethal7,8,9, suggesting that an additional enzymatic activity may be required for the removal of RNA One such enzyme is the Saccharomyces cerevisiae Dna2 helicase10,11,12/endonuclease12, which is essential for cell viability13,14 and is well suited to removing RNA primers of Okazaki fragments15 In addition, Dna2 interacts genetically and physically with several proteins involved in the elongation or maturation of Okazaki fragments10,16 Here we show that the endonucleases Dna2 and Fen1 act sequentially to facilitate the complete removal of the primer RNA The sequential action of these enzymes is governed by a single-stranded DNA-binding protein, replication protein-A (RPA) Our results demonstrate that the processing of Okazaki fragments in eukaryotes differs significantly from, and is more complicated than, that occurring in prokaryotes We propose a novel biochemical mechanism for the maturation of eukaryotic Okazaki fragments

Sodium intercalation chemistry in graphite

Abstract: The insertion of guest species in graphite is the key feature utilized in applications ranging from energy storage and liquid purification to the synthesis of graphene. Recently, it was discovered that solvated-Na-ion intercalation can occur in graphite even though the insertion of Na ions alone is thermodynamically impossible; this phenomenon enables graphite to function as a promising anode for Na-ion batteries. In an effort to understand this unusual behavior, we investigate the solvated-Na-ion intercalation mechanism using in operando X-ray diffraction analysis, electrochemical titration, real-time optical observation, and density functional theory (DFT) calculations. The ultrafast intercalation is demonstrated in real time using millimeter-sized highly ordered pyrolytic graphite, in which instantaneous insertion of solvated-Na-ions occurs (in less than 2 s). The formation of various stagings with solvated-Na-ions in graphite is observed and precisely quantified for the first time. The atomistic configuration of the solvated-Na-ions in graphite is proposed based on the experimental results and DFT calculations. The correlation between the properties of various solvents and the Na ion co-intercalation further suggests a strategy to tune the electrochemical performance of graphite electrodes in Na rechargeable batteries.

Multipole plasmon resonances in gold nanorods

Abstract: The optical properties of gold rods electrochemically deposited in anodic aluminum oxide templates have been investigated. Homogeneous suspensions of rods with an average diameter of 85 nm and varying lengths of 96, 186, 321, 465, 495, 578, 641, 735, and 1175 nm were fabricated. The purity and dimensions of these rod nanostructures allowed us to observe higher-order multipole resonances for the first time in a colloidal suspension. The experimental optical spectra agree with discrete dipole approximation calculations that have been modeled from the dimensions of the gold nanorods.