• Title/Summary/Keyword: ChAT

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Antioxidative and Neuroprotective Effects of Extract and Fractions from Adenophora triphylla (잔대 추출물과 이들 분획물들의 항산화 및 뇌신경세포 보호 효과)

  • Chung, Mi Ja;Lee, Sanghyun;Park, Yong Il;Kwon, Ki Han
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.45 no.11
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    • pp.1580-1588
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    • 2016
  • The 70% ethanol extract from Adenophora triphylla showed a strong antioxidant effect and reduced cytotoxicity of $H_2O_2$ in SK-N-SH cells. The chloroform fraction from A. triphylla extract (AT-CH) among the six fractions showed strong DPPH radical and intracellular reactive oxygen species (ROS) scavenger effects and the highest protective effect against $H_2O_2$-induced SK-N-SH cell death. Bioactivity compounds were purified from AT-CH, and the chemical structures of the compounds were determined as ${\beta}$-sitosterol and daucosterol on the basis of $^1H-NMR$, $^{13}C-NMR$, and EI mass spectra. ${\beta}$-Sitosterol and daucosterol also had protective effects against oxidative stress in SK-N-SH cells. Phospho-p38 MAPK levels were elevated by $H_2O_2$ but were inhibited by treatment with AT-CH and phytosterols (${\beta}$-sitosterol and daucosterol) isolated from AT-CH. These results suggest that AT-CH has brain neuroprotective effects against oxidative stress ($H_2O_2$) by inhibiting activation of p38 pathways and scavenging intracellular ROS.

Synthesis of diamond thin film on WC-Co by RF PACVO (고주파 플라즈마 CVD에 의한 초경합금상에 다이아몬드 박막의 합성)

  • 김대일;이상희;박종관;박구범;조기선;박상현;이덕출
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2000.07a
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    • pp.452-455
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    • 2000
  • Diamond thin films were synthesized on WC-Co substrate at various experimental parameters using 13.56MHz RF PACVD(radio frequency plasma-assisted chemical vapor deposition). In order to increase the nucleation density, the WC-Co substrate was polished with 3$\mu\textrm{m}$ diamond paste. And the WC-Co substrate was pretreated in HNO$_3$: H$_2$O = 1:1 and O$_2$ plasma. In H$_2$-CH$_4$gas mixture, the crystallinity of thin film increased with decreasing CH$_4$concentration at 800W discharge power and 20torr reaction pressure. In H$_2$-CH$_4$-O$_2$gas mixture, the crystallinity of thin film increased with increasing O$_2$concentration at 800W discharge power, 20torr reaction pressure and 4% CH$_4$concentration.

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Diamond Film Growth by Vapor Activation Method Using ${CH_3}OH/{H_2}O$ Gas (HFCVD법에 의한 ${CH_3}OH/{H_2}O$ 혼합기체의 다이아몬드 박막성장에 관한 연구)

  • Lee, Gwon-Jae;Go, Jae-Gwi
    • Korean Journal of Materials Research
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    • v.11 no.12
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    • pp.1014-1019
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    • 2001
  • The diamond thin film was deposited on Si(100) substrate from$CH_3OH/H_2O$mixtured gas using a hot filament chemical vapor deposition(HFCVD) method. The deposition condition for samples has been varried with the$CH_3OH/H_2O$composition. Scanning electron microscopy(SEM) and Raman spectroscopy has been employed for the sample analysis. The diamond sample has been obtained below 20Pa with$CH_3OH/H_2O$mixtured gas. The crystallinity of diamond film improved as the composition $CH_3OH$decreases from 60Vol% to 52Vol%, and the sample structure changed from the cauliflower to the diamond structure. But the sample structure was becomes cauliflower at 50Vol% of in$CH_3OH$ in the $CH_3OH/H_2O$. It was shown that the$CH_3OH$ has threshold composition.

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Reaction Dynamics of CH3 + HBr → CH4 + Br at 150-1000 K

  • Ree, Jongbaik;Kim, Yoo Hang;Shin, Hyung Kyu
    • Bulletin of the Korean Chemical Society
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    • v.34 no.8
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    • pp.2473-2479
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    • 2013
  • The kinetics of the radical-polar molecule reaction $CH_3+HBr{\rightarrow}CH_4+Br$ has been studied at temperatures between 150 and 1000 K using classical dynamics procedures. Potential energy surfaces constructed using analytical forms of inter- and intramolecular interaction energies show a shallow well and barrier in the entrance channel, which affect the collision dynamics at low temperatures. Different collision models are used to distinguish the reaction occurring at low- and high-temperature regions. The reaction proceeds rapidly via a complex-mode mechanism below room temperature showing strong negative temperature dependence, where the effects of molecular attraction, H-atom tunneling and recrossing of collision complexes are found to be important. The temperature dependence of the rate constant between 400 and 1000 K is positive, the values increasing in accordance with the increase of the mean speed of collision. The rate constant varies from $7.6{\times}10^{-12}$ at 150 K to $3.7{\times}10^{-12}$ at 1000 K via a minimum value of $2.5{\times}10^{-12}\;cm^3\;molecule^{-1}\;s^{-1}$ at 400 K.

Pyrolytic Reaction Pathway of Dichloromethane in Excess Hydrogen (과잉수소 반응분위기에서 Dichloromethane 열분해 반응경로에 관한 연구)

  • Won, Yang-Soo
    • Applied Chemistry for Engineering
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    • v.17 no.6
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    • pp.638-643
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    • 2006
  • Pyrolytic reaction study of dichloromethane ($CH_{2}Cl_{2}$) in excess hydrogen was performed to investigate pyrolytic reaction pathways at a pressure of 1 atm with residence times of 0.3~2.0 sec in the temperature range of $525{\sim}900^{\circ}C$. A constant feed molar ratio $CH_{2}Cl_{2}$:$H_{2}$ of 4:96 was maintained through the experiment. Reagent loss and product formation were monitored by using an on-line gas chromatograph, where batch samples were analyzed by GC/MS. Complete destruction(99%) of the parent reagent was observed at temperature near $780^{\circ}C$ with residence time over 1 sec. Major products observed were $CH_{3}Cl$, $CH_{4}$, $C_{2}H_{4}$, $C_{2}H_{6}$, and HCl. Minor products included $CHClCCl_{2}$, CHClCHCl, $CH_{2}CHCl$, and $C_{2}H_{2}$. The pyrolytic reaction pathways to describe the important features of intermediate product distributions and reagent loss, based upon thermodynamic and kinetic principles, were suggested. The results of this work provided a better understanding of pyrolytic decomposition processes which occur during the pyrolysis of $CH_{2}Cl_{2}$ and similar chlorinated methanes.

Shock Tube Study on the Reaction of Methyl Radical with Molecular Oxygen (메틸 라디칼과 산소 분자 반응에 관한 충격관 연구)

  • Shin, Kuan Soo
    • Journal of the Korean Chemical Society
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    • v.39 no.10
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    • pp.769-775
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    • 1995
  • The reaction between $CH_3$ radicals and $O_2$ was investigated in incident shock waves at temperatures between 1390 and 2250 K and densities from 1.5 to 5.3 mol/$m^{+30/3}$ using azomethane as a source of methyl radicals by following the consumption of CH3 radicals with time resolved UV absorption measurements at 213.9 nm. The rate constant expression $k_2=1.35{\times}10^{12}\;exp( - 5900 K/T)\;cm^3 mol^{-1}s^{-1}$ for the reaction of $CH_3 + O_2{\rightarrow}CH_2O + OH$ was derived.

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Dry Etching Characteristics of GaN using a Planar Inductively Coupled CHsub $CH_4/H_2/Ar$ Plasma (평판 유도 결합형 $CH_4/H_2/Ar$ 플라즈마를 이용한 GaN 건식 식각 특성)

  • Kim, Mun-Yeong;Baek, Yeong-Sik;Tae, Heung-Sik;Lee, Yong-Hyeon;Lee, Jeong-Hui;Lee, Ho-Jun
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.48 no.9
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    • pp.616-621
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    • 1999
  • A planar inductively coupled $CH_4/H_2/Ar$plasma was used to investigate dry etch characteristics of GaN as a function of input power, RF bias power, and etch gas composition. Etch rate of GaN increased with input power up to 600 W and was saturated at the higher power. Also, the etch rates increased with increasing RF bias power, composition of $CH_4$ and Ar gas. We achieved the maximum etch rate of $930{\AA}$/min at the input power 400 W, RF bias power 250 W, and operational pressure 10 mTorr. This paper shows that smooth etched surface having roughness less than 1 nm in rms can be obtained by using planar inductively coupled plasma with $CH_4/H_2/Ar$ gas chemistry.

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Effect of Phospho-gypsum on reduction of methane emission from rice paddy soil

  • Ali, Muhammad Aslam;Lee, Chang-Hoon;Kim, Pil-Joo
    • Korean Journal of Environmental Agriculture
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    • v.26 no.2
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    • pp.131-140
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    • 2007
  • Phospho-gypsum a primary waste by-product in phosphate fertilizer manufacturing industry and a potential source of electron acceptors, such as mainly of sulfate and a trace amount of iron and manganese oxides, was selected as soil amendment for reducing methane $(CH_4)$ emissions during rice cultivation. The selected amendment was added into potted soils at the rate of 0, 2, 10, and 20 Mg $ha^{-1}$ before rice transplanting. $CH_4$ flux from the potted soil with rice plant was measured along with soil Eh and floodwater pH during the rice cultivation period. $CH_4$ emission rates measured by closed chamber method decreased with increasing levels of phospho-gypsum application, but rice yield markedly increased up to 10 Mg $ha^{-1}$ of the amendment. At this amendment level, total $CH_4$ emissions were reduced by 24% along with 15% rice grain yield increment over the control. The decrease in total $CH_4$ emission may be attributed due to shifting of electron flow from methanogenesis to sulfate reduction under anaerobic soil conditions.

Influence of Changing Combustor Pressure on Combustion Characteristics and Reaction Zone in the Partially Premixed Flame with $CH_4$, $C_2H_4$ and $C_3H_8$ (부분 예혼합 화염에서 연소실 압력이 연료별($CH_4$, $C_2H_4$, $C_3H_8$) 연소특성과 반응영역에 미치는 영향)

  • Son, Je-Ha;Kim, Jong-Ryul;Choi, Gyung-Min;Kim, Duck-Jool
    • Journal of the Korean Society of Combustion
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    • v.16 no.3
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    • pp.33-40
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    • 2011
  • Combustion experiments were conducted at three different fuels ($CH_4$, $C_2H_4$ and $C_3H_8$) to investigate the effects of combustor pressure (30 ~ -30 kPa) on combustion charateristics and reaction zone structure. Regardless of the fuels, emission index of CO (EICO) increased with decreasing combustor pressure, and EICO of $C_2H_4$ was mostly affected by changing combustor pressure at subatmospheric pressure. In order to observe reaction zone, $OH^*$, $CH^*$ and ${C_2}^*$ chemiluminescence intensity were measured. The sequence of the chemiluminescence intensity peak position was affected by chemical characteristics of fuels rather than changing combustor pressure. The emission zone thickness of $C_2H_4$ and $C_3H_8$, defined by the full width at half maximum (FWHM) of $CH^*$ intensity profile, were increased with decreasing combustor pressure. however, the thickness of $C_2H_4$ exhibited the opposite tendency due to the characteristics of the fuel as the bond structure.

CH4 Dry Reforming on Alumina-Supported Nickel Catalyst

  • Joo, Oh-Shim;Jung, Kwang-Deog
    • Bulletin of the Korean Chemical Society
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    • v.23 no.8
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    • pp.1149-1153
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    • 2002
  • CH4/CO2 dry reforming was carried out to make syn gas on the Ni/Al2O3 catalysts calcined at different temperatures. The Ni/Al2O3 (850 $^{\circ}C)$ catalyst gave good activity and stability w hereas the Ni/Al2O3 $(450^{\circ}C)$ catalyst showed lower activity and stability. The NiO/Al2O3 catalyst calcined at $850^{\circ}C$ for 16 h (Ni/Al2O3 $(850^{\circ}C))$ formed the spinel structure of nickel aluminate, which was confirmed by TPR. The carbon formation rate on the Ni/Al2O3 $(850^{\circ}C)$ catalyst was very low till 20 h, and then steeply increased with reaction time without decreasing the activity for CH4 reforming. The Ni/Al2O3 $(450^{\circ}C)$ catalyst showed high carbon formation rate at the initial reaction time and then, the rate nearly stopped with continuous decreasing the activity for CH4 reforming. Even though the amount of carbon deposition on the Ni/Al2O3 $(850^{\circ}C)$ catalyst was higher than that on the Ni/Al2O3 $(450^{\circ}C)$ catalyst, the activity for CH4ing was also high, which could be attributed to the different type of the carbon formed on the catalyst surface.