• 제목/요약/키워드: oxygen-18

검색결과 1,240건 처리시간 0.034초

XRD의 결정구조로 살펴본 GZO 박막의 온도의존성 (Temperature Dependence of Bonding Structure of GZO Thin Film Analyzed by X-ray Diffractometer)

  • 오데레사
    • 반도체디스플레이기술학회지
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    • 제15권1호
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    • pp.52-55
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    • 2016
  • GZO film was prepared on p-type Si wafer and then annealed at various temperatures in an air conditions to research the bonding structures in accordance with the annealing processes. GZO film annealed in an atmosphere showed the various bonding structure depending on annealing temperatures and oxygen gas flow rate during the deposition. The difference of bonding structures of GZO films made by oxygen gas flows between 18 sccm and 22 sccm was so great. The bonding structures of GZO films made by oxygen gas flow of 18 sccm were showed the crystal structure, but that of 22 sccm were showed the amorphous structure in spite of after annealing processes. The bonding structure of GZO as oxide-semiconductor was observed the trend of becoming amorphous structures at the temperature of $200^{\circ}C$. Therefore, the characteristics of oxide semiconductor are needed to research the variation near the annealing at $200^{\circ}C$.

Oxygen Evolution Reaction at Electrodes of Single Phase Ruthenium Oxides with Perovskite and Pyrochlore Structures$^{**}$

  • 최은옥;권영욱;모선일
    • Bulletin of the Korean Chemical Society
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    • 제18권9호
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    • pp.972-976
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    • 1997
  • Single phase ruthenium oxides with perovskite (ATi1-xRuxO3 (A=Ca, Sr)) and pyrochlore structure (Bi2Ru2O7, Pb2Ru2O6.5) have been prepared reproducibly by solid state reaction methods and their electrocatalytic activities for oxygen evolution have been examined by Tafel plots. Tafel slopes vary from a low value of 42 mV/decade up to 222 mV/decade at room temperature. The high exchange current densities and high Tafel slopes compared with those obtained from the RuO2 DSA electrode at the crystalline single phase metal oxide electrodes suggest that they are better electrocatalysts at low overpotentials. A favorable change in the Tafel slope for the oxygen evolution reaction occurs as the ruthenium content increases. Substitution of Ti for Ru in the perovskite solid solutions enhanced their chemical stability by losing marginal electrochemical activity.

Interaction of Oxygen and $CH_4$ with Molybdenum Oxide Catalysts

  • Kim, C. M.
    • Bulletin of the Korean Chemical Society
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    • 제18권10호
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    • pp.1082-1085
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    • 1997
  • The Near-Edge X-ray Absorption Fine Structure (NEXAFS) technique and Differential Scanning Calorimetry (DSC) were utilized to investigate the reaction of CH4 and O2 on the MoO3/SiO2 catalyst. The NEXAFS results showed that the stoichiometry of the molybdenum oxide catalyst supported on silica was MoO3. MoO3 was reduced to MoO2 when the catalyst was exposed to CH4 at 773 K. NEXAFS results confirm that lattice oxygen is directly related to the process of CH4 oxidation which takes place on the surface of MoO3/SiO2 catalysts. DSC results show that the structure of MoO3 changes around 573 K and this structural change seems to improve the migration of oxygen in the lattice.

꼬막, Tegillarca granosa의 생존과 대사에 미치는 염분의 영향 (Effect of Salinity on Survival and Metabolism of ark shell, Tegillarca granosa)

  • 문태석;신윤경
    • 한국패류학회지
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    • 제26권3호
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    • pp.171-177
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    • 2010
  • We examined physiological responses related to the survival, oxygen consumption and filtration rate of the blood cockle, Tegillaarca granosa as a result of salinity changes. The 44-day $LS_{50}$ (median lethal salinity) at $10^{\circ}C$ for adult and juvenile was 15.8 (confidence limits 13.5-18.2 psu) and 16.2 (confidence limits 14.1-18.4 psu) psu respectively, whereas the 11-day $LS_{50}$ at $25^{\circ}C$ for adult and juvenile was 16.8 psu (confidence limits 12.9-21.2 psu) and 22.4 (confidence limits 20.5-24.7 psu) psu respictively. In conditions of decreasing salinity, Oxygen consumption and filtration rates decreased or varied irregularly as salinity decreased. The results of this study could prove important in investigating causes of mass mortality and managing shellfish aquaculture farms.

A Rhythmicity in the rate of Oxygen Consumption by the Manila clam, Ruditapes philippinarum

  • Kim, Wan-Soo;Rumohr, Heye;Schimid, Michael K.;Koh, Chul-Hwan
    • Journal of the korean society of oceanography
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    • 제31권3호
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    • pp.117-122
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    • 1996
  • Oxygen consumption by the Manila clam, Ruditapes philippinarum (Bivalvia: Veneridae) maintained in a culture tank for 7-10 weeks was measured with an automatic intermittent-flow-respirometer (AIFR). There was evidence for an endogenous tidal rhythm of 12.4 h in oxygen consumption, at irregular intervals of between about 7 and 18 hours during experiments of between 22 h 5 min and 70 h 32 min (duration) recording for fasting animals in constant darkness at constant temperatures in the absence of tidal rhythms.

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계태아(鷄胎兒)의 산소소비(酸素消費)에 대하여 (Study on Oxygen Consumption of Chick Embryo)

  • 유창준
    • 대한수의학회지
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    • 제15권2호
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    • pp.177-180
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    • 1975
  • This study was undertaken to obtain more detailed knowledge of the oxygen consumption rate of chick embryos, of the relationship between the increasing rate of embryo weight and that of oxygen consumption, of the daily increase of oxygen consumption by that of embryo weight, and of the metabolic rate of the White Leghorn eggs. The results obtained are summarized as follows. 1. The average oxygen consumption rate of the chicken embryo at the 3rd day of incubation is 0.8ml/h, STPD. It is strongly suggested that this value can used as a physiological criterion to classify the fertilized and unfertilized eggs, on the other hand oxygen consumption rate of the fertilized eggs reaches a plateau between the 18th and 20th days. 2. There exists a parallel relationship between the increasing rate of embryo weight and that of oxygen consumption rate during the incubation period. 3. There are not exist a parallel relationship between the daily increase of embryo weight and that of oxygen consumption during the whole incubation period. 4. The metabolic rate of chicken embryo(ml/h/g) is highest in the early stage of incubation and it started to decrease sharply until the 8th day follow by slow decrease thereafter.

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SI 가솔린 엔진의 과급 및 흡기가 엔진 성능에 미치는 영향에 대한 연구 (A Study About the Effect of Supercharging and Intake Charge on Engine Performance in Spark Ignition Gasoline Engine)

  • 김기복;진석준;김치원;윤창식;한성현
    • 한국산업융합학회 논문집
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    • 제18권2호
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    • pp.110-118
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    • 2015
  • In this study, it is designed and used the test engine bed which is installed with turbocharger, and in addition to equipped using by oxygen adder. It has been controlled the oxygen volumetric fraction of intake air chrge, and supercharged flow rate into the cylinder of SI 4-stroke engine, and then, has been analyzed engine performance, combustion characteristics, and exhaust emission as analysis parameters. The tested parameters were the oxygen fraction and the variation of engine speed and air-fuel ratio.

Change in Properties of (Ba1-xLax)Fe3+1-tFe4+tO3-y System Depending on Heat Treatment Conditions

  • Lee, Eun-Seok;Lee, Seo-Jin
    • Transactions on Electrical and Electronic Materials
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    • 제18권6호
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    • pp.311-315
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    • 2017
  • The perovskite system $(Ba^{2+}{_{1-x}}La^{3+}{_x})Fe^{3+}{_{1-t}}Fe^{4+}{_t}O_{3-y}$ (y = (1 - x --t)/2) having a composition of x = 0.0, 0.1, 0.2, and 0.3 showedean increase in $Fe^{4+}$ mole ratios with an increase in oxygen partial pressure ($N_2{\rightarrow}air{\rightarrow}O_2$), and with an increasefin s, the $Fe^{3+}$ quantity decreased and oxygen content (3-y value) increased. For each N sampls heat-treated in $N_2$ gas, a considerable weight gain, i.e.g a steadynincrease if oxygen content, was observed in the TGA data on the cooling process. The conductivity values at a constant temperature were in the order of $N_2$$O_2$; the respective log ${\sigma}$ values (${\Omega}^{-1}{\cdot}cm^{-1}$) at 323 K of the BL0 sample were -5.75 (BL0-N), -3.39 (BL0-A), and -0.53 (BL0-O). The mixed valencies of $Fe^{3+}$ and $Fe^{4+}$ ions in each sample were also confirmed by both the oxidation curve above 350 mV and the cathodic reduction curve below 200 mV from cyclic voltammetry.

흰쥐 대뇌세포의 저산소증 모델에서 황련의 활성산소 생성 억제와 신경세포사 억제 (Suppression of Reactive Oxygen Species Production by Water-extracts of Coptidis Rhizoma Enhances Neuronal Survival in a Hypoxic Model of Cultured Rat Cortical Cells.)

  • 최주리;신길조;이원철;문일수;정승현
    • 생명과학회지
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    • 제18권3호
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    • pp.311-317
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    • 2008
  • Pathophysiological oxidative stress results in neuronal cell death mainly due to the generation reactive oxygen species (ROS). In low oxygen situation such as hypoxia and ischemia, excessive ROS is generated. Coptidis Rhizoma (CR) is a traditional medicine used for the incipient stroke. In this report we show that CR water extracts $(1\;{\mu}g/ml)$ exhibited protective effects of neuronal cell death in a hypoxic model (2% $O_2/5%\;CO_2,\;37^{\circ}C,$ 3 hr) of cultured rat cortical cells. We further show that CR water extracts significantly reduced the intensity of green fluorescence after staining with $H_2DCF-DA$ on one hour and three days after hypoxic shock and in normoxia as well. Our results indicate that CR water extracts prevent neuronal death by suppressing ROS generation.

삼기층(三紀層)에 배태(胚胎)된 벤토나이트의 산소(酸素) 및 수소동위원소(水素同位元素) 연구(硏究) (Hydrogen and Oxygen Isotopic Compositions of Tertiary Montmorillonites in Southern Korea)

  • 문희수
    • 자원환경지질
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    • 제19권spc호
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    • pp.131-138
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    • 1986
  • Hydrogen and oxygen isotope ratios of thirteen of the under 2 micron size fraction of the montmorillonites were measured. The oxygen isotopic compositions of these samples range from + 17.0 to +25.1 permil and the hydrogen isotope compositions range from -47.5 to -65.8 permil with an average standard deviation of 0.7 and 2.7 permil, respectively. The oxygen isotope compositions show a positive relationship with stratigraphy whereas the hydrogen isotope compositions do not. It suggest that the montmorillonite attained isotopic equilibrium at the maximum burial depth and ratained their oxygen isotope composition on subsequent uplift. Possibilities of montmorillonite formation by weathering or hydrothermal alteration of volcanic material are eliminated by the ${\delta}D$ and ${\delta}^{18}O$ values of these samples. Calculated formation temperature lie between 29 to $80^{\circ}C$.

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