A chemically regenerative redox fuel cell using (2,2,6,6-tetramethylpiperidin-1-yl)oxyl redox reaction in acid medium

Han, Sang-Beom,Kwak, Da-Hee,Park, Hyun Suk,Park, Jin-Young,Ma, Kyeng-Bae,Won, Ji-Eun,Kim, Do-Hyoung,Kim, Min-Cheol,Park, Kyung-Won Elsevier 2018 Journal of Power Sources Vol.393 No.-

<P><B>Abstract</B></P> <P>(2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) with no free radical and non-volatile characteristic can be utilized as a liquid catalyst instead of O<SUB>2</SUB> at the cathode in a chemical regenerative redox fuel cell with H<SUB>2</SUB> as a fuel at the anode. In this study, the electrochemical properties and performance of TEMPO dissolved in sulfuric acid solution are investigated using half and unit cells. In the half-cell, TEMPO shows an activation energy of 1.27 kcal mol<SUP>−1</SUP> K<SUP>−1</SUP> for the reduction. A chemical regenerative redox fuel cell (CRRFC) using TEMPO as the liquid catalyst exhibits an open circuit voltage of 0.7 V and a maximum power density of 90 mW cm<SUP>−2</SUP> at 30 °C with a low activation loss. The regeneration cycling test of the CRRFC is performed at a constant voltage of 0.4 V under a flow rate of the oxygen-bubbled TEMPO solution. The performance of the CRRFC deteriorates, i.e., a power density of zero measured at >200 min. Thus, a highly efficient regeneration system needs to be developed for a high-performance CRRFC using TEMPO used as a liquid-type oxidant. Furthermore, stable liquid oxidants with relatively high standard reduction potentials can be proposed through various organic compounds.</P> <P><B>Highlights</B></P> <P> <UL> <LI> CRRFC was proposed using TEMPO instead of O<SUB>2</SUB> at the cathode. </LI> <LI> TEMPO showed fairly fast transport and low activation energy for the reduction. </LI> <LI> CRRFC exhibited an open circuit voltage of ∼0.7 V at 30 °C. </LI> <LI> CRRFC exhibited a maximum power density of ∼90 mW cm<SUP>−2</SUP> at 30 °C. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

유리섬유강화 복합절연재료의 열화특성에 관한 연구

이규철,유근민,김경석,박홍태 울산대학교 1996 공학연구논문집 Vol.27 No.2

본 연구에서는 주위 환경 열화에 따른 복합절연재료의 절연특성과 수명을 향상시키기 위해 고온에서 흡습량을 변화시켰을 때와 탈습량을 변화시켰을 때 흡십시료와 탈습시료의 전기적 특성 및 기계적 특성을 조사하였다. 유리섬유 각층의 흡습상수는 각각 1층에서 0.0117, 2층에서 0.0123, 3층에서 0.0152를 나타냈다. 전기적 특성 및 기계적 특성은 복합재료의 흡습에 따라 크게 떨어졌다. 70℃에서 습기가 완전히 건조되어도 흡습전의 전기적 및 기계적 특성을 얻기가 어려운 것으로 나타났다. 수분에 의해 발생한 복합절연재료내에 존재하는 많은 결함들은 에폭시 메트릭스와 필라사이에 존재하였다. The electrical and mechanical properties of moisture absorbed and moisture desorbed specimens were investigated to improve the insulating characteristics and the reliability of composite materials against environment aging. Moisture absorption constants with the layers of glass fiber showed 0.0117 in 1 layer, 0,0123 in 2 layer and 0.0152 in 3 layer, respectively. Although moisture was removed at 70℃, it was impossible to obtain the initial electrical and mechanical properties. Many defects induced by moisture were observed at the interface between epoxy matrix and filler in composite materials.

Dye-Cucurbit[n]uril Complexes as Sensor Elements for Reliable Pattern Recognition of Biogenic Polyamines

Park, Kyeng Min,Kim, Jeeyeon,Ko, Young Ho,Ahn, Youngjoo,Murray, James,Li, Meng,Shrinidhi, Annadka,Kim, Kimoon Chemical Society of Japan 2018 Bulletin of the Chemical Society of Japan Vol. No.

Guest-responsive, Non-proteolytic Harvest of a Cell-sheet using Controllable Host-guest Chemistry

Park, Kyeng Min,Shrinidhi, Annadka,Murray, James,Kim, Kimoon Wiley (John WileySons) 2018 Israel journal of chemistry Vol.58 No.3

Ultrastable Artificial Binding Pairs as a Supramolecular Latching System: A Next Generation Chemical Tool for Proteomics

Park, Kyeng Min,Murray, James,Kim, Kimoon American Chemical Society 2017 Accounts of chemical research Vol.50 No.3

<P>In this Commentary, we discuss cucurbit[7]uril-based ultrastable artificial binding pairs as a supramolecular latching system and how we envision this becoming important tools in proteomics. The limitations of current proteomic techniques are described with an emphasis on the lack of tools to answer questions about the complex and dynamic nature of the proteome. Our thoughts as to how artificial ultrastable binding pairs may be able to address these questions are given especially when they are combined with existing methods.</P>

<i>In Situ</i> Supramolecular Assembly and Modular Modification of Hyaluronic Acid Hydrogels for 3D Cellular Engineering

Park, Kyeng Min,Yang, Jeong-A,Jung, Hyuntae,Yeom, Junseok,Park, Ji Sun,Park, Keun-Hong,Hoffman, Allan S.,Hahn, Sei Kwang,Kim, Kimoon American Chemical Society 2012 ACS NANO Vol.6 No.4

<P>A facile <I>in situ</I> supramolecular assembly and modular modification of biocompatible hydrogels were demonstrated using cucurbit[6]uril-conjugated hyaluronic acid (CB[6]-HA), diaminohexane-conjugated HA (DAH-HA), and tags-CB[6] for cellular engineering applications. The strong and selective host–guest interaction between CB[6] and DAH made possible the supramolecular assembly of CB[6]/DAH-HA hydrogels in the presence of cells. Then, the 3D environment of CB[6]/DAH-HA hydrogels was modularly modified by the simple treatment with various multifunctional tags-CB[6]. Furthermore, we could confirm <I>in situ</I> formation of CB[6]/DAH-HA hydrogels under the skin of nude mice by sequential subcutaneous injections of CB[6]-HA and DAH-HA solutions. The fluorescence of modularly modified fluorescein isothiocyanate (FITC)-CB[6] in the hydrogels was maintained for up to 11 days, reflecting the feasibility to deliver the proper cues for cellular proliferation and differentiation in the body. Taken together, CB[6]/DAH-HA hydrogels might be successfully exploited as a 3D artificial extracellular matrix for various tissue engineering applications.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2012/ancac3.2012.6.issue-4/nn204123p/production/images/medium/nn-2011-04123p_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn204123p'>ACS Electronic Supporting Info</A></P>

Reduction-Sensitive, Robust Vesicles with a Non-covalently Modifiable Surface as a Multifunctional Drug-Delivery Platform

Park, Kyeng Min,Lee, Don-Wook,Sarkar, Bijay,Jung, Hyuntae,Kim, Jeeyeon,Ko, Young Ho,Lee, Kyung Eun,Jeon, Hyesung,Kim, Kimoon WILEY-VCH Verlag 2010 Small Vol.6 No.13

<P>The design and synthesis of a novel reduction-sensitive, robust, and biocompatible vesicle (SSCB[6]VC) are reported, which is self-assembled from an amphiphilic cucurbit[6]uril (CB[6]) derivative that contains disulfide bonds between hexaethylene glycol units and a CB[6] core. The remarkable features of SSCB[6]VC include: 1) facile, non-destructive, non-covalent, and modular surface modification using exceptionally strong host–guest chemistry; 2) high structural stability; 3) facile internalization into targeted cells by receptor-mediated endocytosis, and 4) efficient triggered release of entrapped drugs in a reducing environment such as cytoplasm. Furthermore, a significantly increased cytotoxicity of the anticancer drug doxorubicin to cancer cells is demonstrated using doxorubicin-loaded SSCB[6]VC, the surface of which is decorated with functional moieties such as a folate–spermidine conjugate and fluorescein isothiocyanate–spermidine conjugate as targeting ligand and fluorescence imaging probe, respectively. SSCB[6]VC with such unique features can be used as a highly versatile multifunctional platform for targeted drug delivery, which may find useful applications in cancer therapy. This novel strategy based on supramolecular chemistry and the unique properties of CB[6] can be extended to design smart multifunctional materials for biomedical applications including gene delivery.</P> <B>Graphic Abstract</B> <P>Biocompatible vesicles based on cucurbit[6]uril (CB[6]) can undergo surface modification by host–guest chemistry, internalization into targeted cells by receptor-mediated endocytosis, and triggered release of entrapped drugs in cytoplasm. They serve as a highly versatile multifunctional platform for targeted drug delivery. <img src='wiley_img_2010/16136810-2010-6-13-SMLL201000293-content.gif' alt='wiley_img_2010/16136810-2010-6-13-SMLL201000293-content'> </P>

Sulfur-Doped Porphyrinic Carbon Nanostructures Synthesized with Amorphous MoS₂ for the Oxygen Reduction Reaction in an Acidic Medium

Park, Hyun-Suk,Han, Sang-Beom,Kwak, Da-Hee,Lee, Gyu-Ho,Choi, In-Ae,Kim, Do-Hyoung,Ma, Kyeng-Bae,Kim, Min-Cheol,Kwon, Hye-Jin,Park, Kyung-Won WILEY-VCH 2017 CHEM SUS CHEM Vol.10 No.10

<P>To develop doped carbon nanostructures as non-precious metal cathode catalysts, nanocomposites were synthesized by using SBA-15 and 5,10,15,20-tetrakis(4-methoxyphenyl)-porphyrin-iron(III) chloride with different ratios of amorphous MoS2 precursor. From various analyses, it was found that, during pyrolysis at 900 degrees C under an N-2 atmosphere, the amorphous MoS2 precursor decomposed into Mo and S, facilitating the formation of graphene sheet-like carbon with MoC and doping of sulfur in the carbon. In the nanocomposite formed from 10 wt% MoS2 precursor (denoted as Mo/S/PC-10), most of the MoS2 was decomposed, thus forming S-doped carbon, which was grown on the MoC phase without crystalline MoS2. Furthermore, Mo/S/PC-10 exhibited better performance in the oxygen reduction reaction (specific activity of 1.23 mA cm(-2) at 0.9 V and half-wave potential of 0.864 V) than a commercial Pt catalyst, owing to a heteroatom-doped carbon nanostructure with a fairly high specific surface area. In the polarization curve of the unit-cell performance measured at 80 degrees C under ambient pressure, Mo/S/PC-10 as a cathode catalyst exhibited an optimal power density of 314 mW cm(-2) and a current density of 280 mA cm(-2) at 0.6 V.</P>

품종 및 재배년도에 따른 고춧가루의 Capsaicinoid와 Ascorbic acid의 성분 분석

박영은, 전지영, 이경민, 이재민, 노승우, 이준수 忠北大學校 農業科學硏究所 2016 農業科學硏究 Vol.32 No.1

Pepper (Capsicum annuum L.) is an important part of daily diet in Korea as a seasoning.�ﾠ�ﾠ Major Capsicum cultivars included Capsicum annuum, Capsicum baccatum, Capsicum chinense, Capsicum frutescens and Capsicum pubesecens and among them, Capsicum annuum is cultivated most highly in Korea. In this study, the cultivar and year-to-year variation of capsaicinoids and ascorbic acid contents in peppers were analyzed. Capsaicin contents were in the range of 0.29 to 295.54 mg/100 g and dihydro�ﾠ�ﾠ capsaicin contents were 0.10 to 201.29 mg/100 g, respectively. Ascorbic acid contents were in the range �ﾠ�ﾠ of 25.56 to 1,026.82 mg/100 g. The differences in capsaicinoid and ascorbic acid contents were not sig�ﾠ�ﾠ nificantly different (p < 0.05). In addition, validation parameters were determined to ensure analytical methods' validity. Generally, the results of validation parameters were reliable and satisfactory. This study provides reliable capsaicinoid and ascorbic acid data for the nutritional information.

3D Tissue Engineered Supramolecular Hydrogels for Controlled Chondrogenesis of Human Mesenchymal Stem Cells

Jung, Hyuntae,Park, Ji Sun,Yeom, Junseok,Selvapalam, Narayanan,Park, Kyeng Min,Oh, Kyunghoon,Yang, Jeong-A,Park, Keun Hong,Hahn, Sei Kwang,Kim, Kimoon American Chemical Society 2014 Biomacromolecules Vol.15 No.3

<P>Despite a wide investigation of hydrogels as an artificial extracellular matrix, there are few scaffold systems for the facile spatiotemporal control of mesenchymal stem cells (MSCs). Here, we report 3D tissue engineered supramolecular hydrogels prepared with highly water-soluble monofunctionalized cucurbit[6]uril–hyaluronic acid (CB[6]-HA), diaminohexane conjugated HA (DAH-HA), and drug conjugated CB[6] (drug-CB[6]) for the controlled chondrogenesis of human mesenchymal stem cells (hMSCs). The mechanical property of supramolecular HA hydrogels was modulated by changing the cross-linking density for the spatial control of hMSCs. In addition, the differentiation of hMSCs was temporally controlled by changing the release profiles of transforming growth factor-β3 (TGF-β3) and/or dexamethasone (Dexa) from the hydrolyzable Dexa-CB[6]. The effective chondrogenic differentiation of hMSCs encapsulated in the monoCB[6]/DAH-HA hydrogel with TGF-β3 and Dexa-CB[6] was confirmed by biochemical glycosaminoglycan content analysis, real-time quantitative PCR, histological, and immunohistochemical analyses. Taken together, we could confirm the feasibility of cytocompatible monoCB[6]/DAH-HA hydrogels as a platform scaffold with controlled drug delivery for cartilage regeneration and other various tissue engineering applications.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/bomaf6/2014/bomaf6.2014.15.issue-3/bm401123m/production/images/medium/bm-2013-01123m_0010.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/bm401123m'>ACS Electronic Supporting Info</A></P>