• Title/Summary/Keyword: Oxidation

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What is the Key Step in Muscle Fatty Acid Oxidation after Change of Plasma Free Fatty Acids Level in Rats?

  • Doh, Kyung-Oh;Suh, Sang-Dug;Kim, Jong-Yeon
    • The Korean Journal of Physiology and Pharmacology
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    • v.9 no.3
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    • pp.173-177
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    • 2005
  • The purpose of this study was to discern the critical point in skeletal muscle fatty acid oxidation by changing plasma free fatty acids (FFA) level in rat. In the study, 3 key steps in lipid oxidation were examined after changing plasma FFA level by acipimox. The rates of both palmitate and palmitoylcarnitine oxidation were decreased by decrease of plasma FFA level, however, carnitine palmitoyl transferase (CPT) 1 activity was not changed, suggesting CPT1 activity may not be involved in the fatty acid oxidation at the early phase of plasma FFA change. In the fasted rats, ${\beta}-hydroxy$ acyl-CoA dehydrogenase (${\beta}$-HAD) activity was depressed to a similar extent as palmitate oxidation by a decrease of plasma FFA level. This suggested that ${\beta}-oxidation$ might be an important process to regulate fatty acid oxidation at the early period of plasma FFA change. Citrate synthase activity was not altered by the change of plasma FFA level. In conclusion, the critical step in fatty acids oxidation of skeletal muscles by the change of plasma FFA level by acipimox in fasting rats might be the ${\beta}-oxidation$ step rather than CPT1 and TCA cycle pathways.

Oxidation of carbohydrates and A corbon-13 n. m. r. study of the keto sugars

  • An, Seung-Ho
    • Archives of Pharmacal Research
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    • v.9 no.4
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    • pp.229-232
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    • 1986
  • Three inexpensive oxidation reagents, namely pyridinium chlorochromate, chromium trioxide-dipyridine and nicotinium dichromate were utilized for oxidation of carbohydrates in 78-92% yield. Hydration could be eliminated in the oxidation of pentopyranosides and hexopyranosides, while pentofuranosides had a tendency to be easily hydrated during the oxidation. In the carbon-13 n. m. r. study, the carbonyl function resulted from the oxidation affected on the chemical shifts of $\alpha$- and $\beta$-carbons of methyl 3. 4-O-isopropylidene-$\beta$-D-arabinopyranosid-2-ulose (8) and 1,2 : 4, 5-di-O-isopropylidene-$\beta$-D-erythro-2, 3-hexodiulo-2, 6-pyranose (10) to slightly down fields (0.7-2.6 p. p. m.) compared with the chemical shifts before oxidation. While the carbonyl groups of 1. 2-O-isopropylidene-5-O-ethyloxycarbonyl-$\alpha$-D-erythro-pentofuran-3-ulose (4) and methyl 3, 5-0-isopropylidene-$\alpha$-D-threo-pentofuranosid-2-ulose (6) pushed the $\alpha$-carbons to up fields (3, 2-18.3 p. p. m. However, the order of signals on the spectra before and after oxidation remained unaltered.

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The Effect of The Heat Treatment Condition and the Oxidation Process on the Microstructure of Ag-CdO Contact Materials (Ag-CdO계 전기접점재료의 미세조직에 미치는 열처리 조건과 산화 공정의 영향)

  • Kwon, Gi-Bong;Nam, Tae-Woon
    • Journal of Korea Foundry Society
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    • v.25 no.6
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    • pp.226-232
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    • 2005
  • Contact material is widely used in the field of electrical parts. Ag-CdO material has a good wear resistance and stable contact resistance. In order to establish optimizing heat treatment condition, rolling temperature and oxidation process, we studied the microstructure of Ag-CdO material with various conditions. The experimental procedure were melting using high frequency induction, heat treatment, rolling and internal oxidation. And we experimented on difference process, Post-oxidaion. In this study, we obtained the optimizing heat treatment condition was $700^{\circ}C$ for 15 min. and the optimizing rolling temperature was $730^{\circ}C$. In investigation of the microstructure of oxidized material, coarse oxide and depleted oxidation layer existed. The hardness was average Hv 70. When we used Post-oxidation, oxides were finer than prior process and depleted oxidation layer did not exist. The hardness of Post-oxidation material was average Hv 80. And the optimizing rolling temperature was $800^{\circ}C$.

Characteristics and Formation of Thermal Oxidative Film Silicon Carbide for MOS Devices (MOS 소자용 Silicon Carbide의 열산화막 생성 및 특징)

  • O, Gyeong-Yeong;Lee, Gye-Hong;Lee, Gye-Hong;Jang, Seong-Ju
    • Korean Journal of Materials Research
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    • v.12 no.5
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    • pp.327-333
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    • 2002
  • In order to obtain the oxidation layer for SiC MOS, the oxide layers by thermal oxidation process with dry and wet method were deposited and characterized. Deposition temperature for oxidation layer was $1100^{\circ}C$~130$0^{\circ}C$ by $O_2$ and Ar atmosphere. The oxide thickness, surface morphology, and interface characteristic of deposited oxide layers were measurement by ellipsometer, SEM, TEM, AFM, and SIMS. Thickness of oxidation layer was confirmed 50nm and 90nm to with deposition temperature at $1150^{\circ}C$ and $1200{\circ}C$ for dry 4 hours and wet 1 hour, respectively. For the high purity oxidation layer, the necessity of sacrificial oxidation which is etched for the removal of the defeats on the wafer after quickly thermal oxidation was confirmed.

Study of wastewater-treatment's efficiency using Bacillus subtilis: with an effect of ozonation (Bacillus subtilis를 이용한 폐수처리 효과연구: 오존의 영향을 중심으로)

  • 박영규
    • Journal of environmental and Sanitary engineering
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    • v.17 no.4
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    • pp.29-38
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    • 2002
  • Advanced oxidation of wastewater was studied with a purpose to remove TOC and color by the ozone-assisted Fenton reaction. The optimal conditions were determined by hydrogen peroxide and ozone concentrations. Experimental results indicate that the ozone treatment after Fentons process was found to provide very efficient removal efficiency in the process, avoiding the exclusive ozone treatment. The combined process of ozone in the Fenton oxidation respectively was increased removal efficiences of 10.7% in comparison with exclusive Fenton oxidation. Also, the treatments of ozone after Fenton's oxidation respectively had increased the removal efficiences of 16.%. As a result, the treatment of ozone after Fentons oxidation had the best removal efficiency of approximately 96%. Removal efficiency of color was significantly increased as mush as 26% by the advanced Fenton's oxidation in comparison with exclusive Fenton's oxidation. The removal efficiencies in the biological treatment using Bacillus subtilis after Fenton's oxidation and after Fenton's and ozone's oxidation were increased by 14% and 19% respectively. Although these combined Bacillus subtilis-assisted Fenton's oxidation was determined to be effective method to treat the dyeing wastewater in an economic point of view, the choice of wastewater treatment can be varied depending on water quality.

Two-Step Oxidation of Refractory Gold Concentrates with Different Microbial Communities

  • Wang, Guo-hua;Xie, Jian-ping;Li, Shou-peng;Guo, Yu-jie;Pan, Ying;Wu, Haiyan;Liu, Xin-xing
    • Journal of Microbiology and Biotechnology
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    • v.26 no.11
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    • pp.1871-1880
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    • 2016
  • Bio-oxidation is an effective technology for treatment of refractory gold concentrates. However, the unsatisfactory oxidation rate and long residence time, which cause a lower cyanide leaching rate and gold recovery, are key factors that restrict the application of traditional bio-oxidation technology. In this study, the oxidation rate of refractory gold concentrates and the adaption of microorganisms were analyzed to evaluate a newly developed two-step pretreatment process, which includes a high temperature chemical oxidation step and a subsequent bio-oxidation step. The oxidation rate and recovery rate of gold were improved significantly after the two-step process. The results showed that the highest oxidation rate of sulfide sulfur could reach to 99.01 % with an extreme thermophile microbial community when the pulp density was 5%. Accordingly, the recovery rate of gold was elevated to 92.51%. Meanwhile, the results revealed that moderate thermophiles performed better than acidophilic mesophiles and extreme thermophiles, whose oxidation rates declined drastically when the pulp density was increased to 10% and 15%. The oxidation rates of sulfide sulfur with moderate thermophiles were 93.94% and 65.73% when the pulp density was increased to 10% and 15%, respectively. All these results indicated that the two-step pretreatment increased the oxidation rate of refractory gold concentrates and is a potential technology to pretreat the refractory sample. Meanwhile, owing to the sensitivity of the microbial community under different pulp density levels, the optimization of microbial community in bio-oxidation is necessary in industry.

High-Temperature Oxidation Behavior of Fe-22%Cr-5.8%Al Alloy (Fe-22%Cr-5.8%Al 합금의 고온 산화 거동)

  • Kim, Song-Yi;Choi, Sung-Hwan;Yun, Jung-Yeul;Kong, Young-Min;Kim, Byoung-Kee;Lee, Kee-Ahn
    • Journal of the Korean institute of surface engineering
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    • v.44 no.1
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    • pp.13-20
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    • 2011
  • This study investigated the high temperature oxidation behavior of Fe-22%Cr-5.8%Al alloy and the oxidation kinetics of the alloy were discussed. Bulk samples were prepared by VAM (vacuum arc melting) and hot forging. High temperature oxidation testes were isothermally conducted up to 100 hours in 79%$N_2$+21%$O_2$ environment at three different temperatures ($900^{\circ}C$, $1000^{\circ}C$, $1100^{\circ}C$). The weight gain was measured after oxidation according to oxidation time (2, 4, 6, 8, 10, 15, 20, 25, 30, 60, 80, 100 hours). The weight gain significantly increased with increasing oxidation temperature. As the temperature increased, the oxidized samples showed sequential formation of $Al_2O_3$, Cr-rich oxide, Fe-rich oxide. The activation energy of high temperature oxidation was obtained as 306.63 KJ/mol. $Al_2O_3$ were developed on the surface in the early stage of oxidation, representing protective role of oxidation. However, Fe-based and Cr-based oxides leaded to breakaway of oxide layer, thus resulted in the significant increase of additional oxidation.

The Analysis of Voltage Waveform and Oxidation Growth of Conductor with Series Arc (직렬 아크에 따른 도체의 산화물 증식 및 전압 파형 분석)

  • Choi, Chung-Seog;Kim, Hyang-Kon;Kim, Dong-Ook;Kim, Dong-Woo
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.55 no.3
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    • pp.146-152
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    • 2006
  • In order to analyze the characteristics of series arcs that could happen in poor connections of electrical facilities, we made an apparatus which is similar to actual situation. series arcs are generated between copper and copper, copper and bronze, copper and brass, bronze and bronze, and then oxidation growth and voltage waveform were measured. A very small vibration with constant movement is needed to grow oxidation initially, whereas oxidation growth proceeded without a vibration after a certain amount of time. At first, blue white flame was generated initially between copper and copper, and then yellow flame was generated. In case of contact between copper and copper, the length of oxidation growth was about 7.1[mm] in 90[min]. In case of contact between copper and brass, the length of oxidation growth was about 4.3[mm] in 90[min], When bronze is contacted with copper, the lengths of oxidation growth were about 1.4[mm] in 20[min] and 2.7[mm] in 40[min] respectively, and no more oxidation growth was shown after that. In case of contact between brass and brass, the length of oxidation growth was about 1.2[mm] in 90[min], so it was the smallest compared to other cases. When copper is contacted with copper, the current through the load was about 1.6[A] and the power dissipation increased from 19[W] to 31[W]. In case of oxidation growth between copper and brass, the voltage changed from 8.4[V] to 11[V]. However, the voltage drop and the power dissipation between copper and brass were small compared to oxidation growth between copper and copper. When series arcs were generated between bronze and copper, a peak was shown at the beginning of voltage increase, and 40[min] later, oxidation material was not grown any longer. When oxidation growth occurred, voltage waveform showed irregular waveforms with tiny ripples.

A Study on Evaluation of Oxidation Degradation of Bidiesel and Biodiesel Blended Fuel Distributing in Domestic (국내 유통 바이오디젤 및 바이오디젤 혼합연료의 산화열화 연구)

  • Min, Kyong-Il;Yim, Eui Soon;Na, Byung-Ki;Jung, Choong-Sub
    • Transactions of the Korean Society of Automotive Engineers
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    • v.21 no.4
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    • pp.135-143
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    • 2013
  • In this study, we suggested effective countermeasure of biodiesel oxidation problems by investigating the oxidation degradation of biodiesels derived from variable resources and the level of oxidation stability of current distributing biodiesel blended fuels (2%) in Korea, and oxidation stability change according to storage time (for 3 month) and biodiesel blending ratio (2, 5, 7, 10%). By the composition analysis results of biodiesel from various resources which are possible to distribute in Korea, the biodiesel from animal fat has poor oxidation stability and cold performance, while the biodiesel from coconut and palm kernel which are considered as future potential raw material showed good oxidation stability and cold performance. The oxidation stability level of current distributing biodiesel blended fuels in Korea was excellent with showing over 30 hours (average 68 hours) stability, but the oxidation stability of the blended fuel with animal fat biodiesel having poor oxidation property (1.22 hours) was rapidly decreased to below 32 hours by mixing only 2%. Therefore, we have to pay attention to quality control of oxidation property, because the oxidation stability problem can be caused by increasing biodiesel blending ratio and diversifying raw materials those have worse property.

Fuctional Relationship between Rate of Fatty Acid Oxidation and Carnitine Palmitoyl Transferase I Activity in Various Rat Tissues

  • Cho, Yu-Lee;Do, Kyung-Oh;Kwon, Tae-Dong;Jang, Eung-Chan;Lee, Keun-Mi;Lee, Suck-Kang;Kim, Jong-Yeon
    • The Korean Journal of Physiology and Pharmacology
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    • v.7 no.4
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    • pp.207-210
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    • 2003
  • Lipids play many structural and metabolic roles, and dietary fat has great impact on metabolism and health. Fatty acid oxidation rate is dependent on tissue types. However there has been no report on the relationship between the rate of fatty acid oxidation and carnitine transport system in outer mitochondrial membrane of many tissues. In this study, the rate of fatty acid oxidation and carnitine palmitoyltransferase (CPT) I activity in the carnitine transport system were measured to understand the metabolic characteristics of fatty acid in various tissues. Palmitic acid oxidation rate and CPT I activity in various tissues were measured. Tissues were obtained from the white and red skeletal muscles, heart, liver, kidney and brain of rats. The highest lipid oxidation rate was demonstrated in the cardiac muscle, and the lowest oxidation rate was in brain. Red gastrocnemius muscle followed to the cardiac muscle. Lipid oxidation rates of kidney, white gastrocnemius muscle and liver were similar, ranging from 101 to 126 DPM/mg/hr. CPT I activity in the cardiac muscle was the highest, red gastrocnemius muscle followed by liver. Brain tissue showed the lowest CPT I activity as well as lipid oxidation rate, although the values were not significantly different from those of kidney and white gastrocnemius muscle. Therefore, lipid oxidation rate was highly (p<0.001) related to CPT I activity. Lipid oxidation rate is variable, depending on tissue types, and is highly (p<0.001) related to CPT I activity. CPT I activity may be a good marker to indicate lipid oxidation capacity in various tissues.