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곽진환,현종찬,박재호,정경윤,유승호,윤영수,임희대 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.96 No.-
As promising candidates for next-generation batteries, calcium-ion batteries (CIBs) have attractedsignificant attention because of the lower cost and improved environmental friendliness of Ca metalrelative to those of Li and their potential to deliver higher energy densities. However, their practicalapplication has been limited by the lack of an appropriate electrode that can induce fast Ca cointercalation/deintercalation reactions while providing longer cycle life. In this study, we report bacterialcellulose (BC) with a highly graphitic-like ordered structure as a new and efficient co-intercalation hostfor multivalent Ca ions. The free-standing BC electrode with unique 3D porous morphology possessedultra-fast co-intercalation kinetics, much faster than that for a commercial graphite electrode. Inaddition, we addressed the controversial issue of whether Ca co-intercalation truly occurs in the graphiticlayer. It is demonstrated that the co-intercalation is directly dependent on the degree of carboncrystallinity by using various BC electrodes with different crystallinities at regular intervals. Finally, theeffect of the ordering of the carbon stacking layer on the co-intercalation chemistry waselectrochemically investigated.
세균의 Peptide Deformylase(PDF)를 억제하는 새로운 항균물질의 스크리닝
곽진환,김현주,설민정,서병선,이종국,최수영 대한약학회 2003 약학회지 Vol.47 No.3
Peptide deformylase (PDF) is essential and unique to bacteria, thus making it an attractive target for the discovery of novel antibacterial drugs. PDF deformylates the N-formylmethionine of newly synthesized polypeptides in prokaryotes. In this study, a pdf gene from Staphylococcus aureus 6538p was cloned in pET-14b vector and PDF protein was over-produced in Escherichia coli BL21 (DE3). NH$_2$-terminal His-tagged PDF protein was purified by nickel-nitrilotriacetic acid (Ni-NTA) metal-affinity chromatography. Enzymatic activity of purified 6xHis-tagged PDF was tested on the substrate (formyl-Methionine-Alanine-Serine) by formate dehydrogenase-coupled spectrometric assay of peptide deformylase. For the discovery of new PDF inhibitors from chemical libraries and culture broths of soil bacteria, a target-oriented screening system using a 96-well plate was developed. About 3,000 commercial chemical libraries were tested in this screening system, and 2 chemicals (0.07%) among them showed an inhibitory activity against PDF enzyme. This result showed that a new screening system can be used for the discovery of new PDF inhibitors.
Waste Sawdust-Derived Nanoporous Carbon as a Positive Electrode for Lithium-Ion Storage
곽진환,현종찬,문성박,진형준,임희대,윤영수 한국고분자학회 2020 Macromolecular Research Vol.28 No.13
Sustainable resources, particularly those induced from bio-derived waste materials, can be transformed into useful nanocarbon materials with high functionality. In this study, nanoporous carbon materials (N-CMs) were fabricated from waste sawdust using a simple heating process and a carefully controlled activation process. The waste-induced N-CMs had a high specific surface area of ~3044.6 m2 g-1, a nanoporous structure, and > 6 at.% heteroatoms. These properties led to high electrochemical performance with a specific capacity of ~298 mAh g-1 and excellent cycling stability over 2,000 cycles as a cathode in lithium-ion storage. Moreover, when the N-CMs were assembled with a nanostructured carbon-based anode, all full carbon- based cells could deliver high specific energy and specific power of ~377 Wh kg-1 and ~20,247 W kg-1, respectively, with a long-term cycle life of more than 1,000 cycles.