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Insulation Coating of Fe–Si–Cr Soft Magnetic Powder by Selective Oxidation
Jae‑Young Park,Kwangsuk Park,Bosung Seo,Julien O. Fadonougbo,Tae‑Wook Na,Ki Beom Park,Hyeon‑Tae Im,Nong‑Moon Hwang,Hyung‑Ki Park 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.7
This study examines the insulation coating technology of Fe–Si–Cr powder via selective oxidation annealing, which oxidizeselements selectively by controlling the oxidation potential. The study calculated the oxidation driving force of Fe, Si, andCr, and conducted a thermodynamic analysis of oxidation and reduction conditions according to temperature and oxidationpotential. Based on the results, a selective oxidation annealing was performed in an atmosphere in which Fe is reduced andonly Si and Cr are selectively oxidized. The oxidation potential was controlled through the partial pressure ratio of hydrogenand water vapor. The XPS analysis results confirmed that a Si and Cr complex oxide layer formed on the powder surfaceafter the selective oxidation annealing. Afterward, withstanding voltages were analyzed to evaluate the insulation property. Then, the withstanding voltage of the powder applying the selective oxidation annealing increased significantly comparedto that of the initial powder. Further analysis showed that the powder annealed in an air atmosphere had a significantly lowersaturation magnetic flux density than the initial powder, while the powder applying the selective oxidation annealing hadonly a slightly reduced saturation magnetic flux density.
Distribution of the Fairy Pitta (Pitta nympha) in the South Korea: A focus on protected areas
Gil-Pyo Hong(홍길표),Jae-Hoon Kim(김재훈),Seul-Gi Seo(서슬기),So-Yeon Cho(조소연),Bo-Yeon Hwang(황보연),Jong-Hyun Park(박종현),Seung-Yeon Lee(이승연),Ga-Young Kim(김가영),Wan-Hee Nam(남완희),Ha-Cheol Sung(성하철) 한국조류학회 2021 한국조류학회지 Vol.28 No.2
국내 팔색조(Pitta nympha) 분포 현황을 알아보고자 전국 국립공원 등 보호지역 중심으로 총 19개 지역을 조사하였고, 전문가 네트워크를 통해 자료를 보강하였다. 전국 19개 지역을 조사한 결과 북한산, 지리산 등 내륙지역 7개 국립공원에서는 팔색조가 확인되지 않았고, 경남 거제, 남해, 해남, 장흥 고흥 등 남해안과 인접한 12개 지역에서 팔색조 서식이 확인되었다. 또한 전문가 네트워크를 통해 수집한 팔색조 출현 위치 정보 82건을 분석한 결과, 전국 8개 광역지자체 모두 팔색조 서식이 확인되었고, 내륙지역(26.8%)보다 해안지역(73.2%)에서 더 많이 출현하였다. 연구 결과를 종합해보면, 우리나라의 팔색조는 주로 제주도와 남해안 지역을 중심으로 많이 분포하며, 그 보다 적은 개체수가 내륙 지역에 넓게 분포하고 있는 것으로 나타났다. The present study investigated the current distribution of Fairy Pitta (Pitta nympha) in South Korea. A total of 19 study areas, including protected areas such as national and provincial parks in South Korea were surveyed, and additional data obtained from an expert network. According to the results, Fairy Pitta was absent in seven inland national parks, including Mt. Bukhan and Chiri parks. Fairy Pitta inhabited 12 areas near the southern coast of South Korea, including Geoje, Namhae, Haenam, Jangheung, Goheung, and Gyeongnam Province. The analysis results of 82 datasets obtained from experts with regard to the locations where Fairy Pitta have been spotted showed that the bird inhabits all the eight metropolitan regions in South Korea, and is more frequently spotted in coastal areas (73.2%) than in inland areas (26.8%). The findings demonstrate that Fairy Pitta is mainly distributed in Jeju Island and the southern coast of South Korea, and is distributed in inland areas at relatively lower numbers.
Switching of Photonic Crystal Lasers by Graphene
Hwang, Min-Soo,Kim, Ha-Reem,Kim, Kyoung-Ho,Jeong, Kwang-Yong,Park, Jin-Sung,Choi, Jae-Hyuck,Kang, Ju-Hyung,Lee, Jung Min,Park, Won Il,Song, Jung-Hwan,Seo, Min-Kyo,Park, Hong-Gyu American Chemical Society 2017 NANO LETTERS Vol.17 No.3
<P>Unique features of graphene have motivated the development of graphene-integrated photonic devices. In particular, the electrical tunability of graphene loss enables high-speed modulation of light and tuning of cavity resonances in graphene-integrated waveguides and cavities. However, efficient control of light emission such as lasing, using graphene, remains a challenge. In this work, we demonstrate on/off switching of single- and double-cavity photonic crystal lasers by electrical gating of a monolayer graphene sheet on top of photonic crystal cavities. The optical loss of graphene was controlled by varying the gate voltage V-g, with the ion gel atop the graphene sheet. First, the fundamental properties of graphene were investigated through the transmittance measurement and numerical simulations. Next, optically pumped lasing was demonstrated for a graphene-integrated single photonic crystal cavity at V-g below-0.6 V, exhibiting a low lasing threshold of -4801 mu W, whereas lasing was not observed at V-g above -0.6 V owing to the intrinsic optical loss of graphene. Changing quality factor of the graphene-integrated photonic crystal cavity enables or disables the lasing operation. Moreover, in the double-cavity photonic crystal lasers with graphene, switching of individual cavities with separate graphene sheets was achieved, and these two lasing actions were controlled independently despite the close distance of -2.2 mu m between adjacent cavities. We believe that our simple and practical approach for switching in graphene-integrated active photonic devices will pave the way toward designing high-contrast and ultracompact photonic integrated circuits.</P>
Analysis of Ginsenosides by Thermospray LC/MS
Park, Man-Ki,Park, Jeong-Hill,Hwang, Gwi-Seo,Lee, Mi-Young,Park, In-Jeong The Korean Society of Ginseng 1995 Journal of Ginseng Research Vol.19 No.2
Ginseng saponins were analyzed by thermospray (TSP) LCMS method using ODS column and with acetonitrile/ammonium acetate solution. Optimal condition for TSP Lchfs was found as follows: capillary temperature: 33$0^{\circ}C$ repelled voltage: 200 V, and concentration of ammonium acetate: 0. 05 M. Panaxadiol and panaxatriol type saponins showed characteristic fragment ions. The calibration curve of ginseng saponin showed good linearity with a correlation coefficient of 0.99. Detection limits using selected ion monitoring (SIM) technique were improved by 10~200 times compared to conventional HPLCnnr detection method.
RAW264.7 세포에서 interferon-r 및 LPS에 의해 유도되는 NO생성에 미치는 TALT-35의 영향
박종일,박경석,김종석,박지훈,윤은진,송경섭,서강식,김훈,윤완희,박승길,임규,황병두 충남대학교 생물공학연구소 2006 생물공학연구지 Vol.12 No.-
TALP-35 purified from human term placenta is known to increase microtubule polymerization and stabilize the polymerized microtubule. To examine the effect of TALP-35 on immune system this study was performed. MTT assay was performed to investigate the effect of TALP-35 on the proliferation of RAW264.7 cells. TALP-35 dose dependently suppress the proliferation of RAW264.7 cells at high concentration (above 1 μM) in unstimulated cells, in case of 10 μM TALP-35 treated cells the suppression was 25% but in stimulated cells it was only 15%. Cosedimentation assay was carried out to investigate whether TALP-35 can bind to tubulin of RAW264.7, monocyte/macrophage lineage of mouse, and polymerize it. TALP-35 polymerize the tubulin of RAW264.7 cells and sedimented in dose-dependent manner. To investigate the effect of TALP-35 on the expression of iNOS protein western blotting was performed. The expression level of iNOS was decreased dose dependently in high concentration of TALP-35 treatment. To examine the activity of iNOS, secreted NO was determined by method based on Griess reaction. Interferon-γ and LPS-stimulated production of NO from RAW264.7 cells was decreased dose dependently above 0.1 μM concentration of TALP-35 and 50% is decreased at 10μM of it. This study shows TALP-35 can control cytokine induced-iNOS expression therefore it might control inflammatory diseases.
Seo-Yeon Park,Hye-Lim Jang,Jong-Hun Lee,Myung-Jin Hwang,Youngmin Choi,Haengran Kim,Jinbong Hwang,Dongwon Seo,Sanghe Kim,Jin-Sik Nam 한국산업식품공학회 2016 학술대회 및 심포지엄 Vol.2016 No.04
Nutritional and physicochemical changes of mustard leaf kimchi were examined during fermentation periods up to 3 months. As the fermentation processed, pH decreased, and titratable acidity gradually increased. The crude ash and protein contents increased during fermentation, but crude lipid content was significantly reduced from 5.97 to 5.07%. Crude fiber and carbohydrate showed no distinct changes. Dietary fiber contents were slowly changed between control and 1 month fermentation sample, and were maintained thereafter. The major free sugars of mustard leaf kimchi were fructose and glucose, and the amount of them were significantly decreased at the end of fermentation stage. Lactic acid showed a dramatic increase and reached its maximum at 3 months. All kimchi contained 20 amino acids; in particular, glutamic acid was the highest in mustard leaf kimchi. Amino acid contents fluctuated during fermentation. Except for calcium and selenium, the content of other ingredients (Fe, K, Mg, Na, and Zn) increased with prolonged fermentation time. Fermentation promotes a significant increasing in the content of linoleic acid and DHA. The highest antioxidant vitamins (β-carotene, tocopherol) contents were determined at mustard leaf kimchi fermented for 2 months. The results will provide fundamental data for proposing an appropriate fermentation periods to promote quality of kimchi
Selective GSK-3β inhibitors attenuate the cisplatin-induced cytotoxicity of auditory cells
Park, Hee-Je,Kim, Hyung-Jin,Bae, Gi-Sang,Seo, Sang-Wan,Kim, Do-Yun,Jung, Won-Seok,Kim, Min-Sun,Song, Mi-Young,Kim, Eun-Kyung,Kwon, Kang-Beom,Hwang, Sung-Yeon,Song, Ho-Joon,Park, Cheung-Seog,Park, Rae- Elsevier 2009 Hearing research Vol.257 No.1
<P><B>Abstract</B></P><P>Glycogen synthase kinase-3 (GSK-3) plays an important role in the regulation of apoptosis. However, the role of GSK-3 in the auditory system remains unknown. Here we examined whether the GSK-3-specific inhibitors, SB 216763 and LiCl, could protect against cisplatin-induced cytotoxicity of auditory cells. GSK-3 was activated by cisplatin treatment of HEI-OC1 cells. SB 216763 or LiCl treatments inhibited cisplatin-induced apoptosis in a dose-dependent manner and activated caspase-9, -8 and -3. In rat primary explants of the organ of Corti, SB 216763 or LiCl treatments completely abrogated the cisplatin-induced destruction of outer hair cell arrays. Administration of SB 216763 or LiCl inhibited cochlear destruction and the production of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and IL-6 in cisplatin-injected mice. Furthermore, administration of SB 216763 or LiCl reduced the thresholds of the auditory brainstem response (ABR) in cisplatin-injected mice. Collectively, these results suggest that cisplatin-induced ototoxicity might be associated with modulation of GSK-3 activation.</P>
Park, Hwang-Seo,Seh, Jung-Hun,Lee, Sang-Youb Korean Chemical Society 2002 Bulletin of the Korean Chemical Society Vol.23 No.6
Based on ab initio calculations at the MP2(FULL)/6-31+G**//RHF/6-31G** level, we compare the energetic and mechanistic features of a model reaction for catalytic action of Δ?-3-ketosteroid isomerase (KSL,E.C.5.3,3.1) with those of a corresponding nonenzymatic reaction in aqueous solution. The results show that the two catalytic acid residues,Tyr14 and Asp99, can lower the free energy of activation by 8.6kcal/mol, which is in good agreement with the experimentally predicted~9 kcal/mol,contribution of electrophilic catalyses to the whole enzymatic rate enhancement. The dienolate intermediate formed by proton transfer from the substrate carbon acid to the catalytic base residue (Asp38) ins predicted to be stabilized by 12.0 kcal/mol in the enzymatic reaction, making its formation thermodynamically favorable. It has been argued that enzymes catalyzing the reactions of carbon acids should resolve the thermodynamic problem of stabilizing the enolate intermediate as well as the kinetic porblem of lowering the free energy of activation for porton abstraction. We find that KSI can successfully overcome the thermodynamic difficulty ingerent in the nonenzymatic reaction through the electrophilic catalyses of the two acid residues. Owing to the stabilization of dienolate intermediate, the reketonization step could influence the overall reaction rate more significantly in the KSI- catalyzed reaction than in the nonenzymatic reaction, further supporting the previous experimental findings. However, the electrophilic catalyses alone cannot account for the whole catalygic capability (12-13 kcal/mol), confiming the earlier experimental implications for the invement of additional catalytic components. The present computational study indicates clearly how catalytic residues of KSI resolve the fundamental problems associated with the entropic penalty for forming the rate-limiting transition state and its destabilization in the bulk solvation environment.