Effects of manganese substitution at the B-site of lanthanum-rich strontium titanate anodes on fuel cell performance and catalytic activity

Rath, Manas K.,Ahn, Byung-Guk,Choi, Byung-Hyun,Ji, Mi-Jung,Lee, Ki-Tae Elsevier 2013 Ceramics international Vol.39 No.6

<P><B>Abstract</B></P> <P>Sr<SUB>0.4</SUB>La<SUB>0.6</SUB>Ti<SUB>1−<I>x</I> </SUB>Mn<SUB> <I>x</I> </SUB>O<SUB>3−<I>δ</I> </SUB> with rhombohedral structure has been investigated in terms of their electrochemical performance, redox stability, and electro-catalytic properties for solid oxide fuel cell anodes. The performance of Sr<SUB>0.4</SUB>La<SUB>0.6</SUB>Ti<SUB>1−<I>x</I> </SUB>Mn<SUB> <I>x</I> </SUB>O<SUB>3−<I>δ</I> </SUB> anodes for solid oxide fuel cells strongly depends on the Mn substitution at the B-site of the perovskites. Electrical conductivity of Sr<SUB>0.4</SUB>La<SUB>0.6</SUB>Ti<SUB>1−<I>x</I> </SUB>Mn<SUB> <I>x</I> </SUB>O<SUB>3−<I>δ</I> </SUB> increases with increasing Mn content. X-ray photoelectron spectroscopy analysis reveals that the amount of Mn<SUP>3+</SUP> and Ti<SUP>3+</SUP>, which is an electronic charge carrier, increases with Mn doping. The reduced anode powders with high Mn/Ti ratio show oxygen storage capability and a low carbon deposition rate. Linear thermal expansion coefficients of Sr<SUB>0.4</SUB>La<SUB>0.6</SUB>Ti<SUB>1−<I>x</I> </SUB>Mn<SUB> <I>x</I> </SUB>O<SUB>3−<I>δ</I> </SUB> anodes range from 9.46×10<SUP>−6</SUP> K<SUP>−1</SUP> to 11.3×10<SUP>−6</SUP> K<SUP>−1</SUP>. The maximum power densities of the single cell with the Sr<SUB>0.4</SUB>La<SUB>0.6</SUB>Ti<SUB>0.2</SUB>Mn<SUB>0.8</SUB>O<SUB>3−<I>δ</I> </SUB> anode in humidified H<SUB>2</SUB> and CH<SUB>4</SUB> at 800°C are 0.29Wcm<SUP>−2</SUP> and 0.24Wcm<SUP>−2</SUP>, respectively.</P>

초전도 한류기를 적용한 계통의 3상 단락사고에 대한 EMTDC 시뮬레이션

최효상,김병숙,서용균,나도간,이남재,한병성 전북대학교 공업기술연구소 1998 工學硏究 Vol.30 No.-

We have performed an EMTDC simulation for the current limiting effects of a superconducting fault current limiter (SFCL). A three-phase fault in the 154 kV transmission line between the gaepo and Sungnam substations produced a fault current of up to 60kA. The SFCL with 100 Ω impedance after quench limited the current to 17kA within a half cycle. This limited current is well below the upper limit of a circuit breaker, suggesting the impedance of the SFCL in the transmission line is sufficient.

Upregulation of NAD(P)H:quinone oxidoreductase by radiation potentiates the effect of bioreductive beta-lapachone on cancer cells.

Choi, Eun K,Terai, Kaoru,Ji, In-Mi,Kook, Yeon H,Park, Kyung H,Oh, Eun T,Griffin, Robert J,Lim, Byung U,Kim, Jin-Seok,Lee, Doo S,Boothman, David A,Loren, Melissa,Song, Chang W,Park, Heon Joo Stockton Press 2007 Neoplasia Vol.9 No.8

<P>We found that beta-lapachone (beta-lap), a novel bioreductive drug, caused rapid apoptosis and clonogenic cell death in A549 human lung epithelial cancer cells in vitro in a dose-dependent manner. The clonogenic cell death caused by beta-lap could be significantly inhibited by dicoumarol, an inhibitor of NAD(P)H:quinone oxido-reductase (NQO1), and also by siRNA for NQO1, demonstrating that NQO1-induced bioreduction of beta-lap is an essential step in beta-lap-induced cell death. Irradiation of A549 cells with 4 Gy caused a long-lasting upregulation of NQO1, thereby increasing NQO1-mediated beta-lap-induced cell deaths. Although the direct cause of beta-lap-induced apoptosis is not yet clear, beta-lap treatment reduced the expression of p53 and NF-kappaB, whereas it increased cytochrome C release, caspase-3 activity, and gammaH2AX foci formation. Importantly, beta-lap treatment immediately after irradiation enhanced radiation-induced cell death, indicating that beta-lap sensitizes cancer cells to radiation, in addition to directly killing some of the cells. The growth of A549 tumors induced in immunocompromised mice could be markedly suppressed by local radiation therapy when followed by beta-lap treatment. This is the first study to demonstrate that combined radiotherapy and beta-lap treatment can have a significant effect on human tumor xenografts.</P>

Effect of Transport Time on the Use of Reperfusion Therapy for Patients with Acute Ischemic Stroke in Korea

Choi Jay Chol,Kim Joong-Goo,Kang Chul-Hoo,Bae Hee-Joon,Kang Jihoon,Lee Soo-Joo,Park Jong-Moo,Park Tai Hwan,Cho Yong-Jin,Lee Kyung Bok,Lee Jun,Kim Dong-Eog,차재관,Kim Joon-Tae,Lee Byung-Chul,Lee Ji-Sung,K 대한의학회 2021 Journal of Korean medical science Vol.36 No.11

Background: We investigated the association between geographic proximity to hospitals and the administration rate of reperfusion therapy for acute ischemic stroke. Methods: We identified patients with acute ischemic stroke who visited the hospital within 12 hours of symptom onset from a prospective nationwide multicenter stroke registry. Reperfusion therapy was classified as intravenous thrombolysis (IVT), endovascular therapy (EVT), or combined therapy. The association between the proportion of patients who were treated with reperfusion therapy and the ground transport time was evaluated using a spline regression analysis adjusted for patient-level characteristics. We also estimated the proportion of Korean population that lived within each 30-minute incremental service area from 67 stroke centers accredited by the Korean Stroke Society. Results: Of 12,172 patients (mean age, 68 ± 13 years; men, 59.7%) who met the eligibility criteria, 96.5% lived within 90 minutes of ground transport time from the admitting hospital. The proportion of patients treated with IVT decreased significantly when stroke patients lived beyond 90 minutes of the transport time (P = 0.006). The proportion treated with EVT also showed a similar trend with the transport time. Based on the residential area, 98.4% of Korean population was accessible to 67 stroke centers within 90 minutes. Conclusion: The use of reperfusion therapy for acute stroke decreased when patients lived beyond 90 minutes of the ground transport time from the hospital. More than 95% of the South Korean population was accessible to 67 stroke centers within 90 minutes of the ground transport time.

Effect of Wood Vinegar on the Performance, Nutrient Digestibility and Intestinal Microflora in Weanling Pigs

Choi, J.Y.,Shinde, P.L.,Kwon, I.K.,Song, Y.H.,Chae, Byung-Jo Asian Australasian Association of Animal Productio 2009 Animal Bioscience Vol.22 No.2

Two experiments were conducted to investigate the feeding value of wood vinegar in weanling pigs. In Experiment 1, weanling pigs (n = 224; Landrace ${\times}$Yorkshire ${\times}$Duroc, 21${\pm}$3 d-old, initial BW 6.12${\pm}$0.10 kg) were assigned to four dietary treatments. Different levels of wood vinegar were added to the diets as dietary treatments (0, 0.1, 0.2 and 0.3%). Each treatment comprised 4 replicates with 14 piglets in each. Experimental feeding was conducted for 28 d in two phases (phase I, d 0 to 14 and phase II, d 15 to 28). Feeding of wood vinegar linearly (p<0.05) improved the phase I, phase II and overall ADG and increased (linear, p<0.05) the overall and phase II ADFI. Linear improvements in the apparent fecal digestibility of dry matter (p = 0.013), gross energy (p = 0.019) and crude protein (p = 0.033) were observed as the level of wood vinegar was increased in the diet of pigs. Experiment 2 was conducted to compare dietary wood vinegar with commonly used growth promoters, organic acid (mixture of 21% phosphoric acid, 3.25% propionic acid, 2.8% formic acid, 10% calcium formate and 5% calcium propionate) and antibiotic (aparamycin). A total of 288 weanling piglets (Landrace ${\times}$Yorkshire ${\times}$Duroc, 22${\pm}$2 d-old, initial BW 6.62${\pm}$0.31 kg) were assigned to four treatments with four replicates (18 piglets/pen) for 28 days and fed in 2 phases: phase I, d 0 to 14 and phase II, d 15 to 28. The dietary treatments were control (corn-soybean meal basal diet without antibiotics) and diets containing 0.2% antibiotic, 0.2% organic acid and 0.2% wood vinegar. Pigs fed antibiotic showed higher (p<0.001) ADG and better feed efficiency followed by pigs fed wood vinegar and organic acid diets while those fed the control diet had lowest ADG and poorest feed efficiency. The overall and phase I ADFI was highest (p<0.001) in pigs fed wood vinegar and lowest in pigs fed the control diet. Apparent fecal digestibility of dry matter, gross energy and crude protein was significantly higher (p<0.05) in pigs fed the antibiotic diet when compared with pigs fed the control but comparable among pigs fed antibiotic, organic acid and wood vinegar diets. Higher populations of Lactobacillus (p = 0.004) were noted in the ileum of pigs fed the wood vinegar diet, while the population of coliforms in the ileum and cecum was higher (p<0.001) in pigs fed the control diet when compared with pigs fed antibiotic, organic acid or wood vinegar diets. These results indicated that wood vinegar could improve the performance of weanling pigs by improving the nutrient digestibility and reducing harmful intestinal coliforms; moreover performance of pigs fed wood vinegar was superior to those fed organic acid.

Inhibition of thrombin-induced microglial activation and NADPH oxidase by minocycline protects dopaminergic neurons in the substantia nigra <i>in vivo</i>

Choi, Sang H.,Lee, Da Y.,Chung, Eun S.,Hong, Young B.,Kim, Seung U.,Jin, Byung K. Blackwell Science Ltd 2005 Journal of Neurochemistry Vol.95 No.6

<P>Abstract</P><P>The present study shows that activation of microglial NADPH oxidase and production of reactive oxygen species (ROS) is associated with thrombin-induced degeneration of nigral dopaminergic neurons <I>in vivo</I>. Seven days after thrombin injection in the rat substantia nigra (SN), tyrosine hydroxylase immunocytochemistry showed a significant loss of nigral dopaminergic neurons. This cell death was accompanied by localization of terminal deoxynucleotidyl transferase-mediated fluorecein UTP nick-end labelling (TUNEL) staining within dopaminergic neurons. This neurotoxicity was antagonized by the semisynthetic tetracycline derivative, minocycline, and the observed neuroprotective effects were associated with the ability of minocycline to suppress NADPH oxidase-derived ROS production and pro-inflammatory cytokine expression, including interleukin-1&bgr; and inducible nitric oxide synthase, from activated microglia. These results suggest that microglial NADPH oxidase may be a viable target for neuroprotection against oxidative damage.</P>

Health Indicators Related to Disease, Death, and Reproduction

Choi, Jeoungbin,Ki, Moran,Kwon, Ho Jang,Park, Boyoung,Bae, Sanghyuk,Oh, Chang-Mo,Chun, Byung Chul,Oh, Gyung-Jae,Lee, Young Hoon,Lee, Tae-Yong,Cheong, Hae Kwan,Choi, Bo Youl,Park, Jung Han,Park, Sue K. The Korean Society for Preventive Medicine 2019 Journal of Preventive Medicine and Public Health Vol.52 No.1

One of the primary goals of epidemiology is to quantify various aspects of a population's health, illness, and death status and the determinants (or risk factors) thereof by calculating health indicators that measure the magnitudes of various conditions. There has been some confusion regarding health indicators, with discrepancies in usage among organizations such as the World Health Organization the, Centers for Disease Control and Prevention (CDC), and the CDC of other countries, and the usage of the relevant terminology may vary across papers. Therefore, in this review, we would like to propose appropriate terminological definitions for health indicators based on the most commonly used meanings and/or the terms used by official agencies, in order to bring clarity to this area of confusion. We have used appropriate examples to make each health indicator easy for the reader to understand. We have included practical exercises for some health indicators to help readers understand the underlying concepts.

Effects of Decreased RH in the Greenhouse on the Vase life and Quality of Cut Rose ‘Lovely Lydia’

Hyungwon Choi,Suong T.T. Ha,Toan K. Nguyen,Woori Kim,Byung-Chun In,Jin-Hee Lim 한국원예학회 2017 한국원예학회 학술발표요지 Vol.2017 No.5

Genetic Diversity and Population Structure Analysis of Korean Native Chrysanthemums using SNP Markers

Toan K. Nguyen,Hyung-Won Choi,Jae-Han Jeong,Jaewoong Yu,Byung-Chun In,Jin-Hee Lim 한국원예학회 2016 한국원예학회 학술발표요지 Vol.2016 No.10

Binding Modes of New Bis-Ru(II) Complexes to DNA: Effect of the Length of the Linker

Kwon, Byung-Hyang,Choi, Byung-Hoon,Lee, Hyun-Mee,Jang, Yoon-Jung,Lee, Jae-Cheol,Kim, Seog-K. Korean Chemical Society 2010 Bulletin of the Korean Chemical Society Vol.31 No.6

Bis-[dipyrido[3,2-$\alpha$:2',3'-c]phenazine)$_2$(1,10-phenanthroline)$_2Ru_2$]$^{2+}$ complexes (bis-Ru(II) complexes) tethered by linkers of various lengths were synthesized and their binding properties to DNA investigated by normal absorption and linear dichroism spectra, and fluorescence techniques in this study. Upon binding to DNA, the bis-Ru(II) complex with the longest linker (1,3-bis-(4-pyridyl)-propane), exhibited a negative $LD^r$ signal whose intensity was as large as that in the DNA absorption region, followed by a complicate $LD^r$ signal in the metal-to-ligand charge transfer region. The luminescence intensity of this bis-Ru(II) complex was enhanced. The observed $LD^r$ and luminescence results resembled that of the [Ru(1,10-phenanthroline)$_2$ dipyrido[3,2-$\alpha$:2',3'-c]phenazine]$^{2+}$ complex, whose dipyrido[3,2-$\alpha$:2',3'-c]phenazine (dppz) ligand has been known to intercalate between DNA bases. Hence, it is conclusive that both dppz ligands of the bis-Ru(II) complex intercalate. The binding stoichiometry, however, was a single intercalated dppz per ~ 2.3 bases, which violates the "nearest binding site exclusion" model for intercalation. The length between the two Ru(II) complexes may be barely long enough to accommodate one DNA base between the two dppz ligands, but not for two DNA bases. When the linker was shorter (4,4'-bipyridine or 1,2-bis-(4-pyridyl)-ethane), the magnitude of the LD in the dppz absorption region, as well as the luminescence intensity of both bis-Ru(II) complexes, was half that of the bis-Ru(II) complex bearing a long linker. This observation can be elucidated by a model whereby one of the dppz ligands intercalates while the other is exposed to the aqueous environment.