• Title/Summary/Keyword: oxygen effect

Search Result 4,638, Processing Time 0.032 seconds

Effect of Flashing Light on Oxygen Production Rates in High-Density Algal Cultures

  • Park, Kyong-Hee;Kim, Dong-Il;Lee, Choul-Gyun
    • Journal of Microbiology and Biotechnology
    • /
    • v.10 no.6
    • /
    • pp.817-822
    • /
    • 2000
  • A proper flashing light is expected to enhance microalgal biomass productivity and photosynthetic efficiency. The effect of flashing light on high-density Chlorella kessleri (UTEX 398) cultures was studied using light-emitting diodes. A frequency modulator was designed to flash LEDs, and the device successfully provided wide range of frequencies and various duty cycles of flashing. A relatively high frequencies of 10, 20 and 50 kHz were used in this study. These frequencies have very short flashing time ($2-50{\mu}s$), which corresponded to the time constant of the light reaction of photosynthesis. The specific oxygen production rates of photosynthesis under flashing light were compared with those under an equivalent continuous light in specially designed illumination cuvette. The specific oxygen production rates under flashing light were 5-25% higher than those under the continuous light. A range of cell concentration was discovered, where the benefit of flashing light was maximized. The photosynthetic efficiency was also higher under flashing light with frequencies of over 1 kHz, which was a clear indication of flashing light effect and the degree of mutual shading could by overcome by flashing lights, particularly at high-density algal cultures.

  • PDF

Effect of Kaempferol on the Cytotoxicity Induced Oxygen Free Radicals in Skin Fibroblast Derived from Human In Vitro

  • Lee, Jai-Kyoo;Ha, Dae-Ho
    • Biomedical Science Letters
    • /
    • v.14 no.3
    • /
    • pp.193-198
    • /
    • 2008
  • In order to evaluate on the effect of kaempferol on the cytotoxicity of oxygen tree radicals, XTT assay was performed to determine the cell viability after skin fibroblasts derived from human (Detroit 51) that were treated with various concentrations of hydrogen peroxide $(H_2O_2)$. And also, the effect of kaempferol on the cytotoxicity induced by H202 that was examined by cell viability, lactate dehydrogenase (LDH) activity and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity in these cultures. $H_2O_2$ decreased cell viability in dose-dependent manner in these cultures and the $XTT_{90}\;and\;XTT_{50}$ values were determined at concentration of $35{\mu}M\;and\;90{\mu}M$ of $H_2O_2$ after skin fibroblasts derived from human were treated with $15{\sim}90{\mu}M$ of $H_2O_2$ for 6 hours, respectively. $H_2O_2$ was highly toxic on cultured skin fibroblasts derived from human by toxic criteria of Brenfreund and Puerner (1984). In the protective effect of kaempferol on $H_2O_2$-induced cytotoxicity, kaempferol increased DPPH radical scavenging activity and significantly decreased LDH activity. From these results, it is suggested that oxygen tree radical, $H_2O_2$, was highly toxic on cultured skin fibroblasts derived from human, and also kaempferol of flavonoid showed the protection on $H_2O_2$-induced cytotoxicity.

  • PDF

Effect of Amino Acids and Dissolved Oxygen on Expression of Invertase in Recombinant Saccharomyces cerevisiae (재조합 Saccharomyces cerevisiae의 Invertase 발현에 미치는 아미노산과 용존산소의 영향)

  • 신해헌;조정섭;변유량;박혜영
    • Microbiology and Biotechnology Letters
    • /
    • v.20 no.3
    • /
    • pp.348-354
    • /
    • 1992
  • In order to improve the productivity of invertase by recombinant Saccharomyces cerevisiae containing SUC2 gene, the effect of amino acids and dissolved oxygen concentration on the gene expression was investigated. Optimal concentrations of leucine and histidine for cell growth and cloned gene expression were 0.03 gig and 0.04 gig, respectively, expressed as the ratio of amino acid/glucose. The lack or excess of leucine and histidine has inhibitory effect on cell growth and invertase expression. In batch culture, the less aeration was, the higher invertase activity was. In continuous culture at a dilution rate of 0.09 h 1 with controlled dissolved oxygen tension, invertase activity increased dramatically at DOT levels below 5% air saturation, and a maximum activity of 215.54 KUlg cell was obtained under unaerated condition.

  • PDF

Computer based FEM stabilization of oxygen transport model for material and energy simulation in corroding reinforced concrete

  • Hussain, Raja Rizwan
    • Computers and Concrete
    • /
    • v.12 no.5
    • /
    • pp.669-680
    • /
    • 2013
  • This paper unveils a new computer based stabilization methodology for automated modeling analysis and its experimental verification for corrosion in reinforced concrete structures under the effect of varying oxygen concentration. Various corrosion cells with different concrete compositions under four different environmental conditions (air dry, submerged, 95% R.H and alternate wetting-drying) have been investigated under controlled laboratory conditions. The results of these laboratory tests were utilized with an automated computer-aided simulation model. This model based on mass and energy stabilization through the porous media for the corrosion process was coupled with modified stabilization methodology. By this coupling, it was possible to predict, maintain and transfer the influence of oxygen concentration on the corrosion rate of the reinforcement in concrete under various defined conditions satisfactorily. The variation in oxygen concentration available for corrosion reaction has been taken into account simulating the actual field conditions such as by varying concrete cover depth, relative humidity, water-cement ratio etc. The modeling task has been incorporated by the use of a computer based durability model as a finite element computational approach for stabilizing the effect of oxygen on corrosion of reinforced concrete structures.

THE EFFECT OF OXYGEN ON PERCHLORATE REDUCTION IN A BIOFILM REACTOR

  • Choi, Hyeok-Sun
    • Environmental Engineering Research
    • /
    • v.12 no.4
    • /
    • pp.148-154
    • /
    • 2007
  • The purpose of this research was to investigate the effects of low concentration of oxygen on reduction of perchlorate, especially low perchlorate influent concentrations in a biofilm reactor, as well as the effect of flow pattern in a biofilm reactor. Dissolved oxygen averaging 1 mg/L did not inhibit reduction of influent perchlorate from 23 to $426\;{\mu}g/L$ in the biofilm reactors when sufficient acetate was added, probably due to limitation of oxygen diffusion into the biofilm. Influent perchlorate ranging from 23 to $426\;{\mu}g/L$ was reduced to below detection level ($4\;{\mu}g/L$) in the presence of 1 mg/L dissolved oxygen (DO). Chloride was produced in a ratio of $0.37gCl^-/g{ClO_4}^-$ and $0.35gCl^-/g{ClO_4}^-$ in plug flow and recirculation biofilm reactor which is similar to stoichiometric amount ($0.36gCl^-/g{ClO_4}^-$) indicating complete perchlorate reduction at $426\;{\mu}g/L$ of ${ClO_4}^-$ feeding. At $23\;{\mu}g/L$L influent perchlorate, total biomass solids were 3.18 g and 2.81 g in the plug flow and recirculation biofilm reactors. The most probable number(MPN) analysis for perchlorate-reducing bacteria showed $10^4$ to $10^5\;cells/cm^2$ in both biofilm reactors throughout the experiments. The effluent perchlorate concentrations were not significantly different in the two different flow regimes, plug flow and recirculation biofilm reactors.

Investigation on Thermal and Chemical Effects of CO2 in Oxygen Enriched Flame (산소부화화염내 CO2의 열 및 화학적 효과에 대한 연구)

  • Kum Sung Min;Lee Chang Eon;Han Ji Woong
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.29 no.5 s.236
    • /
    • pp.617-624
    • /
    • 2005
  • An analysis of the effects of $CO_{2}$ on fundamental combustion characteristics was performed in Oxygen enriched condition by comparing the laminar burning velocities, flame structures, fuel oxidation paths. Fictitious $CO_{2}$ was introduced to discriminate the chemical reaction effects of $CO_{2}$ from the thermal effects. PREMIX code was utilized to evaluate the laminar burning velocities. OPPDIF code was utilized to investigate the flame structure and fuel oxidation path variation. The contributions of thermal effects on laminar burning velocities are dominant at lowly oxygen-enriched condition but those of chemical reaction effects become dominant at highly oxygen-enriched condition. Chemical reaction effects caused the additional flame temperature decrease besides thermal effects and oxygen-leakage increase in non-premixed flame. Specific fuel oxidation path and CO production path is enhanced in spite of overall decrement of fuel consumption rate by chemical reaction effects of$CO_{2}$.

Effect of Reduction-Reoxidation Firing on PTCR Properties of Sm-doped Barium Titanate Ceramics (Sm이 첨가된 티탄산바륨의 PTCR 특성에 대한 환원-재산화의 영향)

  • Chun, Myoung-Pyo;Myoung, Seong-Jae;Han, Ik-Hyun
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • 2005.11a
    • /
    • pp.35-38
    • /
    • 2005
  • The effect of reduction and re-oxidation firing on the PTCR properties of Sm-doped Barium Titanate ceramics was investigated for the application of multilayered PTC thermistor. The lattice parameter a, c decreases monotonically with increasing oxygen concentration in the reoxidation atmosphere, which seems to be related with the electrostatic Coulomb interaction between oxygen vancancy and nearest other atoms. With increasing oxygen concentration, the resistivity at room temperature and the magnitude of resistivity jump as a function of temperature increased in the region of oxygen concentration of 0 $\sim$ 10%. However, the resistivity at room temperature and the magnitude of resistivity jump is nearly constant and saturated in the region of oxygen concentration of 10 $\sim$ 20%. These phenomena is considered to be related with the variation of oxygen and barium-vancany concentration near the grain boundary.

  • PDF

Increased antioxidant enzyme activities and scavenging effect of oxygen free radicals by Jwagyuyeum and Woogyuyeum (좌귀음(左歸飮)과 우귀음(右歸飮)에 의(依)한 활성(活性) 산소류(酸素類)의 소거작용(消去作用)과 항산화(抗酸化) 효소계(酵素系)의 활성(活性) 증가(增加) 효과(效果)에 대(對)한 연구(硏究))

  • Jeong, Ji-Cheon
    • The Journal of Korean Medicine
    • /
    • v.17 no.1 s.31
    • /
    • pp.21-36
    • /
    • 1996
  • This study was undertaken to examine the effect of Jwagyuyeum and Woogyuycum, being known to reinforce Kidney-yin and yang, on the activities of endogenous antioxidant enzymes and the production of oxygen free radicals in the liver and kidney tissues, Alterations in enzyme activities were observed after in vivo treatment in rats, Jwagyuyeum and Woogyuyeum caused a significant increase in the activities of superoxide dismutase(SOD) and catajase Jwagyuyeum significantly increased the activity of glutathione peroxidase in both liver and kidney, but the enzyme activity was not significantly altered by Woogyuyeum. Treatment in vitro of Jwagyuyeum and Woogyuyeum decreased the production of oxygen free radicals in a dose-dependent fashion. These results suggest that Jwagyuyeum and Woogyuyeum stimulate the activities of antioxidant enzymes and inhibit directly the production of oxygen free radicals. These effects of both herbs may contribute to prevent the oxygen free radical-induced impairment of cell function.

  • PDF

The Effect of Oxygen Content on the Glass Forming Ability and Mechanical Properties of the Zr-based Amorphous Alloy Return Scrap (Zr기지 비정질 합금 스크랩의 비정질 형성능 및 기계적 성질에 미치는 산소함량의 영향)

  • Kim, Sung-Gyoo;Lee, Byung-Chul;Park, Heung-Il
    • Journal of Korea Foundry Society
    • /
    • v.35 no.4
    • /
    • pp.75-79
    • /
    • 2015
  • Commercial Zr-based amorphous alloy was recycled and oxygen was introduced during the recycling process. The oxygen content can have a great effect on the glass forming ability and the mechanical properties of the alloy. Therefore, it was closely examined. The initial oxygen content in the raw material was 1,244 ppm. It was increased to 3,789 ppm in the alloy after ten recycling processes. As the recycling processes were repeated, the oxygen content increased. Specifically, after four recycling processes, it increased sharply as compared to that after three recycling processes. After ten recycling processes, the glass transition temperature (Tg) increased from 613 K to 634 K and the crystallization temperature (Tx) increased from 696 K to 706 K. On the other hand, the super-cooled liquid region (${\Delta}T=Tx-Tg$) decreased slightly from 83 K to 72 K while the reduced glass transition temperature (Trg = Tg/Tm) was 0.63, remaining constant even when the oxygen content was increased. These results indicated that the increased oxygen content deteriorated the glass forming ability. The bending strength as determined in a three-point bending test showed a sharp decrease from 3,055 to 2,062 MPa as the oxygen content was increased from 1,244 ppm to 3,789 ppm; the extension was also decreased from 3.02 to 1.74 mm. These findings meant that the alloy became brittle.

Experimental Studies on Oxygen Tolerance and Poisoning under Hyperbaric Oxygen Environment (고압산소환경(高壓酸素環境)에서의 산소중독(酸素中毒) 및 내성(耐性)에 관(關)한 실험적(實驗的) 연구(硏究))

  • Lee, Won-Chang
    • Korean Journal of Veterinary Research
    • /
    • v.9 no.1
    • /
    • pp.11-22
    • /
    • 1969
  • Experimental studies were performed to observe the difference in tolerance of small animals to oxygen poisoning, and also to examine the effects of certain drug for it. The three experimental groups consisted of mature rat group, immature rat group and mouse group. The animals were exposed to 5 atm. of 100% oxygen using hyperbaric chamber, and they were observed for oxygen poisoning by pulmonary and central nervous system manifestation. The tolerance to oxygen poisoning was represented by half fatality time in each experimental group. The drug applied was ammonium chloride $NH_4Cl$ and it was administered intraperitoneally in various dosages for particular attribution of its prophylactic effect. The following conclusions were made; 1. The immature rat group showed the higher degree of tolerance to oxygen poisoning, as evidenced by a more prolonged half fatality time in the group. No significant difference in the half fatality time between the mature rat and the mouse group was observed. 2. The fact that the immature group showed the higher degree of tolerance as compared with the mature rat group represented by delayed onset of convulsion. 3. There was a remarkable difference in the Lung Weight/Body Weight ratio between the experimental and control group. 4. The animals with a shorter half fatality time uniformally displayed an earlier onset of convulsive seizure as the sign of oxygen poisoning and a significant elevated Lung Weight/Body Weight ratio. 5. Ammonium chloride at the dosage of 450mg per kg body weight had the most pronounced prophylactic effect on oxygen poisoning.

  • PDF