• 제목/요약/키워드: 과잉산소

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Electrical Properties of SrBi$_2$$Nb_2$>$O_9$ Thin Films deposited by RF Magnetron Sputtering Method (RF 마그네트론 스퍼터링법에 의해 증착된 SrBi$_2$$Nb_2$>$O_9$ 박막의 전기적 특성에 관한 연구)

  • Zhao, Jin-Shi;Choi, Hoon-Sang;Lee, Kwan;Choi, In-Hoon
    • Korean Journal of Materials Research
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    • v.11 no.4
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    • pp.290-293
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    • 2001
  • The SrBi$_2$Nb$_2$O$_{9}$ (SBN) thin films were deposited on p-type(100) Si substrates by rf magnetron sputtering to confirm the Possibility of Pt/SBN/Si structure for the application of nondestructive read out ferroelectric random access memory (NDRO- FRAM). The SBN thin films were deposited by co-sputtering method with Sr$_2$Nb$_2$O$_{7}$ (SNO) and Bi$_2$O$_3$ ceramic targets. The SBN thin films deposited at room temperature were annealed at $700^{\circ}C$ for 1hr in $O_2$ ambient. The structural and electrical properties of SBN with different power ratios of targets were measured by x-ray diffraction(XRD), scanning electron microscopy(SEM), capacitance-voltage(C-V), and current-voltage(I-V). The C-V curves of the SBN films showed hysteresis curves of a clockwise rotation showing ferroelectricity. When the Power ratio of the SNO/Bi$_2$O$_3$ targets was 120 W/100 W, the SBN thin films had excellent electrical properties. The memory window of SBN thin film was 1.8 V-6.3 V at applied voltage of 3 V-9 V and the leakage current density was 1.5 $\times$ 10$^{-7}$ A/$\textrm{cm}^2$ at applied voltage of 5 V The composition of SBN thin films was analysed by electron probe X-ray micro analyzer(EPMA) and the atomic ratio of Sr:Bi:Nb with pawer ratio of 120 W/100 W was 1:3:2.

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Induction of antioxygenic enzymes as defense systems in plant cells against low temperature stress : (I) Accumulation of pyruvate in cells during cold treatment and activation of antioxygenic enzymes during post-chilling period (식물의 냉해에 대한 생체방어기구로서 항산소성 효소의 유도 : (1) 저온처리중 pyruvate의 세포내 축적과 상온환원후 항산소성 효소의 활성화)

  • Kim, Jong-Pyung;Hahn, Chang-Kyun;Jung, Jin
    • Applied Biological Chemistry
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    • v.34 no.2
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    • pp.162-167
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    • 1991
  • In an attempt to explore the mechanistic aspects of chilling injury in plants and their defensive measures against the low temperature stress, the time sequential measurements of pyruvate, superoxide radicals$(O_{\overline{2}})$ and antioxygenic enzymes during whole period of injury-inducing treatment were performed using mostly rice seedlings. Pyruvate was substantialy accumulated in leaf tissues during the exposure period to $5^{\circ}C$ of the seedlings ; the relative extent of the accumulation was increased with increasing time of the cold treatment. When the cold-treated plants were translocated to ambient temperature$({\sim}25^{\circ}C)$, the accumulation started to dissipate, concomitantly accompaning a remarkable increase in the $O_{\overline{2}}$ level of tissues. Superoxide dismutase(SOD) and catalase were also activated during post-chilling period, although they showed a considerable lag time for activation. In contrast, glutathione peroxidase, another antioxygenic enzyme in cells, was not activated at all by preceding cold treatment of plants. The uptake of exogenous $O_{\overline{2}}$ by the roots of rice seedlings resulted in increase in the activities of SOD and catalase in root tissues. The supply of $H_2O_2$ to plan st brought about the activation of catalase in situ, while failing to exert any effect on the activation state of glutathione peroxidase. The results obtained in this work suggest that pyruvate accumulation in cells is the direct cause of the overproduction of $O_{\overline{2}}$ and thereby other toxic activated oxygen species, and that SOD and catalase may play a crucial role in the protection of plant cells against active oxygen-mediated chilling injury.

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Effect of Ulmus macrocapa Ethanolic Extracts on Anti-oxidant Activity and Melanin Synthesis in B16F1 Cells (B16F1세포에서 항산화 활성 및 멜라닌 합성에 대한 유백피 에탄올 추출물의 효능)

  • Kwon, Eun-Jeong;Park, Hye-Jung;Kim, Moon-Moo;Lee, Kyeong Rok;Hong, Il;Lee, Do Gyeong;Oh, Yunghee
    • Journal of Life Science
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    • v.24 no.9
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    • pp.946-951
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    • 2014
  • Melanin plays a key role in the protection of skin from ultraviolet light that generates reactive oxygen species (ROS), such as superoxide, hydroxyl radical, singlet oxygen and hydrogen peroxide. However, the ROS leading to the oxidation of lipids, proteins and DNA are involved in the overproduction of melanin that is known to cause melasma, age spots and freckles. Among the herb medicines, Ulmus macrocarpa used in this study was reported to contain flavonoids as a main component. The aim of this study is to investigate the whitening and anti-oxidant effects of Ulmus macrocarpa ethanolic extracts (UMEE) in B16F1 cells. UMEE below $3.12{\mu}g/ml$ did not show cytotoxicity. In an anti-oxidant experiment, UMEE showed not only high reducing power and scavenging activity on DPPH, but it was also observed that UMEE exhibit an inhibitory effect on lipid peroxidation. UMEE did not display an inhibitory effect on tyrosinase activity in vitro. However, UMEE inhibited melanin synthesis in B16F1 cells. In addition, UMEE reduced the expression levels of tyrosinase and tyrosinase-related protein-2 (TRP-2), which are key enzymes in melanogenesis. These results indicate that UMEE exert a whitening effect through the inhibition of both tyrosinase and TRP-2 expressions as well as anti-oxidant activity, suggesting that UMEE could have the functional potential for a whitening effect on the skin.

Interpretation of Blood Gas Analysis During Hypothermic Cardiopulmonary Bypass (저체온 체외순환시 혈액가스분석의 판독과 체온과의 상관관계)

  • Song, Sun-Ok
    • Journal of Yeungnam Medical Science
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    • v.6 no.1
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    • pp.121-131
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    • 1989
  • The temperature-corrected values of blood gas analysis were compared to uncorrected values in 40 cases of open heart surgery under moderate hypothermic cardiopulmonary bypass. The results were as follows. 1. The corrected value of pH was significantly higher than uncorrected value, and it's relationship was ${\Delta}pH=-0.015$ ${\Delta}Temp+0.005$(r=0.81, P<(0.01). 2. The corrected value of $PCO_2$ was lower than uncorrected value, and it's relationship was ${\Delta}PCO_2=1.11$ ${\Delta}Temp+1.81$(r=0.50, P<0.01). 3. The corrected value of $PO_2$ was lower than uncorrected value, and it' s relationship was ${\Delta}PO_2=5.21$ ${\Delta}Temp-1.45$(r=0.32, P<0.01). But there was no clinical significance. 4. The corrected values of $HCO_{3^-}$, base excess, $CO_2$ content and oxygen saturation were similar with uncorrected values. In summery, the values of pH and $PCO_2$were significantly changed by temperature-correction. Because of the neutral point of water (pH=pOH) rises as temperature falls and it change in parallel with the changes in blood pH, a corrected pH of 7.4, $PaCO_2$ of 40mmHg during deep hypothermia would reflect a profound respiratory acidosis. Therefore, the use of the uncorrected value at $37^{\circ}C$ is more preferable and valid means of assessing acid-base management regardless of actual patient temperature.

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Optimization of the Medium and Fermentation Conditions with Erythritol Producing Moniliella suaveolens var. nigra (에리스리톨 생산 균주인 Moniliella suaveolens var. nigra를 이용한 배지 및 발효조건의 최적화)

  • Choe, Byeong-Uk;Park, Hong-U
    • KSBB Journal
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    • v.14 no.5
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    • pp.628-632
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    • 1999
  • Optimization of the medium and fermentation conditions for erythritol production has been studied. We have found that the optimal carbon source was glucose at the concentration of 400 g/L. The optimal temperature was 3$0^{\circ}C$ with excessive aeration. Improved erythritol productivity was achieved by reducing the yeast extract from 5 g/L to 3g/L while adding 2.7 g/L urea, 1.79g/L $K_2HPO_4, and 0.18g/L MgSO$_4$. 7$H_2O. The erythritol productivity increased from 0.747 g/L/h to 1.071 g/L/h and the yield increased from 31.4% to 45.2%. The byproduct glycerol was reduced from 96.6g/L to 45.7g/L as well. We have performed 5L fermentation with and without the pH control. The erythritol productivity with the pH control was about 30% lower than that without pH control. Excessive foaming of 5L fermentation has been observed during fermentation.

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Effect of Injector Cooling on Ignition of Cryogenic Spray (분사기 냉각이 초저온 분무의 점화에 미치는 영향)

  • Kim, Do-Hun;Lee, Jin-Hyuk;Koo, Ja-Ye
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.40 no.3
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    • pp.222-229
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    • 2012
  • The cooling of a injector effects on the vapor pressure of cryogenic oxidizer spray, and it decides the phase transition point at the ignition process, when the combustion chamber pressure increases drastically. The phase transition of oxidizer spray affects the ignition characteristics, and several ignition tests with the LOx/$GCH_4$ uni-element coaxial swirl injector was performed in the different initial temperatures of oxidizer injector, in order to investigate the effect of injector cooling on the ignition transient characteristics. At the transition point of oxidizer phase, where the combustion chamber pressure increased over the LOx vapor pressure, the temporary quenching phenomenon of the flame occurred. The lower temperature of chilled down injector and tubing tends to move up the phase transition earlier.

Nitrogen Removal in Fluidized Bed and Hybrid Reactor using Porous Media (다공성 담체를 이용한 유동상 및 하이브리드 반응기에서의 질소제거)

  • Jun, Byong-Hee
    • Journal of Korean Society of Environmental Engineers
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    • v.27 no.5
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    • pp.542-548
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    • 2005
  • A fluidized bed reactor containing porous media has been known to be effective for nitrogen and organic matters removal in wastewater. The porous media which attached microbes plays important roles in simultaneous nitrification/denitrification (SND) due to coexistence of oxic, anaerobic and anoxic zone. For SND reaction, oxygen and organic substrates should be effectively diffused from wastewater into the intra-carrier zone. However, the overgrowth heterotrophic microbes at the surface of porous media may restrict from substrates diffusion. From these viewpoints, the existence and effect of heterotrophic bacteria at surface of porous media might be the key point for nitrogen removal. A porous media-membrane hybrid process was found to have improved nitrogen removal efficiency, due to stimulated denitrification as well as nitrification. Microelectrode studies revealed that although intra-media denitrification rate in a conventional fluidized bed was limited by organic carbon, this limitation was reduced in the hybrid process, resulting in the increased denitrification rate from 0.5 to $4.2\; mgNO_3-N/L/hr$.

Maximal Oxygen Debt, Lactate and Excess Lactate in Men with Low Hematocrit Ratio (헤마토크?????? 비율이 낮은 사람에 있어서 최대 산소 부채와 과잉젖산 사이의 관계)

  • Kim, Dai-Sung;Nam, Kee-Yong
    • The Korean Journal of Physiology
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    • v.2 no.2
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    • pp.53-61
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    • 1968
  • Maximal oxygen debt, lactate and excess lactate were measured in 13 men with low hematocrit ratio before and after maximal exercise. Maximal exercise run was performed on a treadmill and the duration of run was 2 minutes 45 seconds in each subject. Hematocrit ratio ranged between 35 and 47%, the mean being 39.8%. The following results were obtained. 1. Maximal oxygen debt expressed on basis of body weight increased as the hematocrit ratio decreased. The correlation coefficient between the two was r= -0.770. 2. The time necessary for decreasing to 50% of total maximal $O_2$ debt(half time) became longer as the hematocrit ratio decreased. In normal men the half time was about 4 minutes and at the longest it was 12 minutes in men with the lowest hematocrit ratio. 3. The lactate concentration reached its peak value after 3 minutes of recovery. Thereafter, the time course of decrease in lactate concentration coincided roughly with that of respiratory oxygen debt curve. To reach to the resting level, however, it took longer time than that of respiratory oxygen debt. 4. Resting concentrations of lactate was 1.28 mM/l, pyruvate 0.13 mM/l and L/P ratio was 9.8. Peak value of ${\Delta}L$ after exercise reached to the value of 10.4 mM/l and ${\Delta}L/P$ reached 26.0. Peak excess lactate after exercise was 6.34 mM/l. 5. The part of oxygen debt accounted for by the oxygen equivalent of excess lactate was only 38.4%. A better relationship between lactate and oxygen debt was observed and the part of oxygen debt accounted for by the oxygen equivalent of lactate was 63.3%. 6. Peak value of lactate after maximal exercise increased as the hematocrit ratio decreased. 7. Respiratory oxygen debt of 100 ml/kg was accounted for by lactate more than 60% and only 30% was by excess lactate. 8. Excess lactate was not a good index of respiratory oxygen debt.

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Ferroelectric Properties $\textrm{SrBi}_{2}\textrm{Ta}_{2}\textrm{O}_{9}$ Thin Films Deposited by RF Magnetron Sputtering Technique (RF magnetron sputtering법에 의해 제조된 $\textrm{SrBi}_{2}\textrm{Ta}_{2}\textrm{O}_{9}$박막의 강유전 특성에 관한 연구)

  • Park, Sang-Sik;Yang, Cheol-Hun;Yun, Sun-Gil
    • Korean Journal of Materials Research
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    • v.7 no.6
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    • pp.505-509
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    • 1997
  • FRAM(Ferroelectric Random Access memory)에의 응용을 위해 rf magnetron sputtering법을 이용하여 SrB $i_{2}$T $a_{2}$ $O_{9}$(SBT)박막을 증착하였다. 사용된 기판은 Pt/Ti/Si $o_{2}$Si이었으며 50$0^{\circ}C$에서 증착한 후 80$0^{\circ}C$의 산소 분위기 하에서 1시간 동안 열처리하였다. 증착시 증착 압력을 변화시켜 가면서 이에 따른 특성의 변화를 고찰하였다. 박막내의 Bi와 Sr의 부족을 보상하기 위해 20mole%의 Bi $O_{2}$와 30mole%의 SrC $O_{3}$를 과잉으로 넣어 타겟을 제조후 사용하였고 박막들의 두께는 300nm의 두께를 가지며 증착압력에 따라 다른 미세 구조르 보였다. 10mtorr에서 증착한 박막의 조성은 S $r_{0.6}$B $i_{3.8}$Ta/ sub 2.0/ $O_{9.0}$이었다. 이 SBT 박막의 잔류 분극(2 $P_{r}$)과 보전계(2 $E_{c}$)값은 각각 인가 전압 5V에서 18.5 $\mu%C/$\textrm{cm}^2$과 150kV/cm이었고, signal/noise비는 3V에서 4.6을 나타내었다. 5V의 bipolar pulse하에서 $10^{10}$cycle까지 피로 현상이 나타나지 않았으며, 누설 전류 밀도는 133kV/cm에서 약 1x$10^{-7A}$$\textrm{cm}^2$의 값을 보였다.을 보였다.

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Effect of Soybean Curd Residue Fermented by Monascus pilosus on the High fat Diet-Induced Obese Mice (Monascus pilosus로 발효시킨 비지의 항비만 효과)

  • Lee, Sang-Il;Lee, Ye-Kyung;Kim, Soon-Dong;Lee, In-Ae;Choi, Jongkeun;Suh, Joo-Won
    • Journal of Applied Biological Chemistry
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    • v.57 no.1
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    • pp.7-15
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    • 2014
  • This study investigated anti-obesity and antioxidant effects of dietary non-fermented soybean crud residue (SCR) and fermented SCR by Monascus pilosus (FSCR) in high-fat induced-obese mice. SCR and FSCR were supplemented with high-fat diet at 2% (wt/wt) dose for 8 weeks. Both SCR and FSCR significantly lowered body weight, epididymal fat weight and weight gain rate compared to high-fat diet control (HC) group and FSCR group showed lowest weight gain rate. In addition, it was observed that serum and hepatic lipid profiles including triglyceride, total cholesterol, LDL-cholesterol and HDL-cholesterol were significantly improved by supplementing SCR or FSCR. Furthermore, SCR and FSCR administration showed increase of glutathione content and decrease of hepatic lipid peroxide content, serum aminotransferase activity, and hepatic xanthine oxidase activity. On the other hand, activities of reactive oxygen species scavenging enzyme such as superoxide dismutase, glutathione S-transferase and glutathione peroxidase in two test groups were higher than those of HC. Lastly, in comparison with SCR, FSCR was more effective in restoring obesity-related biomarkers to normal level in high-diet induced obese mice. In conclusion, the present study indicates that FSCR could have not only anti-obese effects such as inhibition of abdominal fat accumulation, but also protective effects of cardiovascular disease such as atherosclerosis by decreasing serum and hepatic lipid contents. Furthermore, these results suggest that experimental diets in this study could alleviate hepatic damage caused by overproduction of reactive oxygen spices (ROS) due to obesity via inhibition of ROS generating activities and induction of ROS scavenging activities.