• Title/Summary/Keyword: low oxygen treatment

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Peculiarities of ReBaCuO superconductor preparation

  • Fan, Zhanguo;Soh, Dea-Wha;Li, Ying-Mei;Park, Jung-Cheol;Korobova, N
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2001.07a
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    • pp.913-916
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    • 2001
  • From 1994 the cooperation between NEU of China and MJU of South Korea for study of ReBaCuO (Re=Rare earth elements) superconductors has been carried out. The progress has been got in following projects. Critical current density ($J_c$) of YBaCuO superconductor prepared by Melting Textured Growth (MTG) was improved. In the preparation of textured YBaCuO, 20 wt.% of YBaCuO 211 phase was added, which would be climactic for the microcracks in the textured YBaCuO. The effects of the 211 phase and Ag content on the superconductivity were studied and discussed in detail. The improved $J_c$ value was reached to 8$\times$10^4 A/cm^2 (77K,0T). Single phase $YbBa_{2}Cu_{3}O_{x}$ superconductor was sintered by the traditional powder metallurgical method, and its reaction process was studied. In recent years, NdBaCuO superconductor is being performed. The behavior of $Nd_{4}Ba_{2}Cu_{2}O_{10}$(Nd422 phase) and the solid solubility, x in the superconductor $Nd_{1+x}Ba_{2-x}Cu_{3}O_{y}$ by the heat treatment in the low oxygen partial pressure (1%) or Ar at $950{\circ}C$ were investigated. The zone-melting process was used to make oriented NdBaCuO superconductor in order to increase the critical current density.

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Evaluation of Anti-Oxidant and Anti-Inflammatory Activities of Ganoderma lucidum Cultured on Hulled Barley (겉보리에서 배양한 영지버섯 추출물의 항산화 및 항염증 효능 평가)

  • Seo, Kyoung Hee;Kim, Yeon Hwa;Lee, Young Min;Ghosh, Mithun;Park, Kang Min;Park, Dong Hyun;Kim, Jin Seong;Lim, Beong Ou
    • Korean Journal of Medicinal Crop Science
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    • v.25 no.1
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    • pp.29-36
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    • 2017
  • Background: Ganoderma lucidum cultured on hulled barley was investigated as a potential natural source of antioxidants and anti-inflammatory agents. Methods and Results: The yields from Ganoderma lucidum cultured on hulled barley water and ethanol extract were 17.69% and 25.77%, respectively. The antioxidant activity of Ganoderma lucidum cultured on hulled barley extracts was confirmed by various methods including assayss of 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2-azino-bis-(3-ethylbenzo thiazoline-6-sulfonic acid) (ABTS), nitrite radical scavenging, and $Fe^{3+}$ to $Fe^{2+}$ reducing power activity. The ethanol extract of Ganoderma lucidum cultured on hulled barley showed improved DPPH, ABTS and nitrite radical scavenging activity compared with the water extract. After treatment of RAW264.7 cells with Ganoderma lucidum cultured on hulled barley ethanol extracts, the cell viability compared with the control was 92.82%, even at a concentration of $3,000{\mu}g/m{\ell}$. The ethanol extract inhibited reactive oxygen species (ROS) generation in RAW264.7 cells stimulated with $H_2O_2$, even at low concentrations. In addition, the ethanol extract showed an inhibitory effects on the production of lipopolysaccharide-induced nitric oxide (NO) in RAW264.7 cells. Conclusions: This study suggests that the extract of Ganoderma lucidum cultured on hulled barley is a potential source of natural antioxidants and anti-inflammatory agents.

Synthesis and Characterization of LSGM Solid Electrolyte for Solid Oxide Fuel Cell (연료전지용 LSGM 페로브스카이트계 전해질의 합성 및 특성 연구)

  • Seong, Young-Hoon;Jo, Seung-Hwan;Muralidharan, P.;Kim, Do-Kyung
    • Journal of the Korean Ceramic Society
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    • v.44 no.12
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    • pp.696-702
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    • 2007
  • The family of (Sr,Mg)-doped $LaGaO_3$ compounds, which exhibit high ionic conductivity at $600-800^{\circ}C$ over a wide range of oxygen partial pressure, appears to be promising as the electrolyte for intermediate temperature solid oxide fuel cells. Conventional synthesis routes of (Sr,Mg)-doped $LaGaO_3$ compounds based on solid state reaction have some problems such as the formation of impurity phases, long sintering time and Ga loss during high temperature sintering. Phase stability problem especially, the formation of additional phases at the grain boundary is detrimental to the electrical properties of the electrolyte. From this point of view, we focused to synthesize single phase (Sr,Mg)-doped $LaGaO_3$ electrolyte at the stage of powder synthesis and to apply relatively low heat-treatment temperature using novel synthesis route based on combustion method. The synthesized powder and sintered bulk electrolytes were characterized by XRD, TG-DTA, FT-IR and SEM. AC impedance spectroscopy was used to characterize the electrical transport properties of the electrolyte with the consideration of the contribution of the bulk lattice and grain boundary to the total conductivity. Finally, relationship between synthesis condition and electrical properties of the (Sr, Mg)-doped $LaGaO_3$ electrolytes was discussed with the consideration of phase analysis results.

A study on the comparison of coated nitrifying bacteria on nitrification efficiency and distribution of nitrifying bacteria

  • Kwon, Hyun-Jin;Yoon, Joung-Yee;Chae, Jong-San;Kim, Dong-Jin
    • 한국생물공학회:학술대회논문집
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    • 2005.10a
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    • pp.434-438
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    • 2005
  • Nitrification characteristics and performance of wastewater treatment plants depend on not only temperature, pH, and dissolved oxygen of the wastewater but also species, distribution, and their metabolic stages of nitrifying bacteria. Due to their low specific growth rate, nitrifying bacteria are easy to wash out of the reactor and need long time to start-up and recover from damaged nitrifiers community. In order to overcome this limitation, nitrifying bacteria were coated on a polyurethane-based media. Laboratory and pilot-scale reactor had been designed and operated to compare the effect of coated nitrifying bacteria on wastewater nitrification efficiency and performance. Furthermore, the species and quantitative distribution of nitrifying bacteria were also investigated in the suspension and on the media. The results showed that nitrifier-coated reactor had better nitrification efficiency and performance than the control experiments. It also demonstrated that the amounts of total nitrifying bacteria of a coated reactor was higher than other reactors and it increased with operation time and wastewater temperature.

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A Review of Flame Retarding Polyacrylonitrile (PAN) Fibers and Composites (난연성 폴리아크릴로니트릴 고분자 섬유 및 복합소재 연구 동향)

  • Kim, Jongho;Ku, Bon-Cheol
    • Composites Research
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    • v.32 no.6
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    • pp.342-348
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    • 2019
  • Development of flame retarding polymer based materials has been studied actively due to the increase in use of polymers. The post treatment of manufactured fibers or the introduction of flame retardant into fibers is representative method for the way to improve the flame retardancy. Among the polymers, polyacrylonitrile (PAN), which is a precursor of carbon fiber, has been widely used for clothes. Due to low flame retardancy of PAN fiber (LOI value: 17~18%), the improvement of flame retardancy of PAN fiber is needed. In this review paper, we report preparation methods for the fabrication of post-treated (oxidization or chemical reaction) flame-retarding PAN fibers and composites composed of PAN and organic/inorganic materials (SiO2, 2D materials or CNT).

Effect of Alginic Acid on Experimentally Induced Arthropathy in Rabbit Model (토끼의 관절병증에 미치는 알긴산올리고당의 치료효과)

  • Bai, Young-Hoon;An, Tae-Hun;Lim, Sung-Chul;Pak, Sok-Cheon;Lee, Jae-Chang;Kang, Nam-Hyun;Bae, Chun-Sik
    • Korean Journal of Veterinary Research
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    • v.42 no.2
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    • pp.153-162
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    • 2002
  • For the induction of arthropathy, 5% hydrogen peroxide($H_2O_2$) was injected for 5 weeks into the intraarticular space of the New Zealand white rabbits to damage articular cartilage. Alginic acid of low molecular weight (2%) made from macromolecular alginate treated with enzyme was administered into articular space at the dose of 5 mg/kg twice a week for 3 and 6 weeks using 1 ml syringe and 26 G needle. Saline was injected for the control. Tissues surrounding the articulation were obtained for the measurements of superoxide dismutase(SOD) activity as a major antioxidant enzyme and malondialdehyde (MDA) as a lipid peroxidation level. Histopathologic examination on the surface of articular cartilage was carried out. Data showed that injection of hydrogen peroxide for 5 weeks had led to the induction of free radical damage and of articular cartilage change as confirmed by microscopic observation. The application of hydrogen peroxide caused a gradual increase in the SODs and MDA. These patterns were similar after 3 and 6 weeks of alginate treatment. Furthermore, microscopic examinations revealed that hydrogen peroxide caused flaking, fibrillation, fissuring, denudation, and hypocellularity in the articular surfaces. In conclusion, lipid peroxidation was demonstrated in the articular cartilage by the administration of hydrogen peroxide in the rabbit model. This lipid peroxidation could be caused by oxygen free radicals. The histologic and enzymatic correlations on lipid peroxidation in the articulation have provided a better understanding of arthropathy. It is possible to take advantage of these findings to evaluate effective alginate dosage more efficiently.

Pig Skin Gelatin Hydrolysates Attenuate Acetylcholine Esterase Activity and Scopolamine-induced Impairment of Memory and Learning Ability of Mice

  • Kim, Dongwook;Kim, Yuan H. Brad;Ham, Jun-Sang;Lee, Sung Ki;Jang, Aera
    • Food Science of Animal Resources
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    • v.40 no.2
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    • pp.183-196
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    • 2020
  • The protective effect of pig skin gelatin water extracts (PSW) and the low molecular weight hydrolysates of PSW generated via enzymatic hydrolysis with Flavourzyme® 1000L (LPSW) against scopolamine-induced impairment of cognitive function in mice was determined. Seventy male ICR mice weighing 20-25 g were randomly assigned to seven groups: Control (CON); scopolamine (SCO, 1 mg/kg B.W., intraperitoneally (i.p.); tetrahydroaminoacridine 10 [THA 10, tacrine; 10 mg/kg B.W. per oral (p.o.) with SCO (i.p.)]; PSW 10 (10 mg/kg B.W. (p.o.) with SCO (i.p.); PSW 40 (40 mg/kg B.W. (p.o.) with SCO (i.p.); LPSW 100 (100 mg/kg B.W. (p.o.) with SCO (i.p.); LPSW 400 (400 mg/kg B.W. (p.o.) with SCO (i.p.). All treatment groups, except CON, received scopolamine on the day of the experiment. The oxygen radical absorbance capacity of LPSW 400 at 1 mg/mL was 154.14 μM Trolox equivalent. Administration of PSW and LPSW for 15 weeks did not significantly affect on physical performance of mice. LPSW 400 significantly increased spontaneous alternation, reaching the level observed for THA and CON. The latency time of animals receiving LPSW 400 was higher than that of mice treated with SCO alone in the passive avoidance test, whereas it was shorter in the water maze test. LPSW 400 increased acetylcholine (ACh) content and decreased ACh esterase activity (p<0.05). LPSW 100 and LPSW 400 reduced monoamine oxidase-B activity. These results indicated that LPSW at 400 mg/kg B.W. is a potentially strong antioxidant and contains novel components for the functional food industry.

Influence of Electron Beam Irradiation on the Electrical Properties of ZnO Thin Film Transistor (전자빔 조사가 ZnO 박막의 전기적 특성 변화에 미치는 영향)

  • Choi, Jun Hyuk;Cho, In Hwan;Kim, Chan-Joong;Jun, Byung-Hyuk
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.30 no.1
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    • pp.54-58
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    • 2017
  • The effect of low temperature ($250^{\circ}C$) heat treatment after electron irradiation (irradiation time = 30, 180, 300s) on the chemical bonding and electrical properties of ZnO thin films prepared using a sol-gel process were examined. XPS (X-ray photoelectron spectroscopy) analysis showed that the electron beam irradiation decreased the concentration of M-O bonding and increased the OH bonding. As a result of the electron beam irradiation, the carrier concentration of ZnO films increased. The on/off ratio was maintained at ${\sim}10^5$ and the $V_{TH}$ values shifted negatively from 11 to 1 V. As the irradiation time increased from 0 to 300s, the calculated S. S. (subthreshold swing) of ZnO TFTs increased from 1.03 to 3.69 V/decade. These values are superior when compared the sample heat-treated at $400^{\circ}C$ representing on/off ratio of ${\sim}10^2$ and S. S. value of 10.40 V/decade.

INJECTION STRATEGY OF DIESEL FUEL FOR AN ACTIVE REGENERATION DPF SYSTEM

  • Lee, C.H.;Oh, K.C.;Lee, C.B.;Kim, D.J.;Jo, J.D.;Cho, T.D.
    • International Journal of Automotive Technology
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    • v.8 no.1
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    • pp.27-31
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    • 2007
  • The number of vehicles employing diesel engines is rapidly rising. Accompanying this trend, application of an after-treatment system is strictly required as a result of reinforced exhaust regulations. The Diesel Particulate Filter (DPF) system is considered as the most efficient method to reduce particulate matter (PM), but the improvement of a regeneration performance at any engine operation point presents a considerable challenge by itself. Therefore, the present study evaluates the effect of fuel injection characteristics on regeneration performance in a DOC and a catalyzed CR-DPF system. The temperature distribution on the rear surface of the DOC and the exhaust gas emission were analyzed in accordance with fuel injection strategies and engine operating conditions. A temperature increase more than BPT of DPF system was obtained with a small amount fuel injection although the exhaust gas temperature was low and flow rate was high. This increase of temperature at the DPF inlet cause PM to oxidize completely by oxygen. In the case of multi-step injection, the abrupt temperature changes of DOC inlet didn't occur and THC slip also could not be observed. However, in the case of pulse type injection, the abrupt injection of much fuel results in the decrease of DOC inlet temperatures and the instantaneous slip of THC was observed.

A Role of Unsaturated Fatty Acid in Animal Reproductive Cells and Biology

  • Hwangbo, Yong;Kim, Hwa-Young;Lee, Yu-Rim;Lee, Seung Tae;Lee, EunSong;Cheong, Hee-Tae;Yang, Boo-Keun;Park, Choon-Keun
    • Reproductive and Developmental Biology
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    • v.40 no.2
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    • pp.15-22
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    • 2016
  • As a one of unsaturated fatty acid, polyunsaturated fatty acids (PUFAs) have multiple actions: as precursor of prostaglandins (PGs), steroid hormone synthesis and energy production in animal reproduction. PUFAs, which include omega-3 (n-3) and omega-6 (n-6), are derived from the diet and changed by diet, species, breed and season. The plasma membrane of spermatozoa in mammals contain various PUFAs. These composition of PUFAs regulate the membrane fluidity and cause lipid peroxidation via generation of reactive oxygen species (ROS). Induced lipid peroxidation by ROS decreased viability and motility of spermatozoa, and it is reduced by addition of antioxidant and low concentration of PUFAs. Because oocytes of animal have a high lipid components, process of oocyte maturation and embryo development are influenced by PUFAs. In in vitro study, oocyte maturation, embryo development, intracellular cAMP and MAPK activity were increased by treatment of n-3 ${\alpha}$-linolenic acid (ALA) during maturation, whereas n-6 linoleic acid (LA) negatively influenced. Also, inhibition of fatty acid metabolism in oocyte influenced blastocyst formation of cattle. PGs are synthesized from PUFAs and various PUFAs influence PGs via regulation of PG-endoperoxide synthase (PTGS). Steroid hormone synthesis from cholesterol is regulated by expression of steroid acute regulator (StAR) protein and mRNA. Exogenous n-3 and n-6 PUFAs altered sex hormone in animal through stimulate or inhibit StAR activity. Because PUFAs altered PG and steroid hormone synthesis, follicular development was influenced by PUFAs. This effect of unsaturated fatty acid could provide information for improvement of reproductive ability in animals.