• Title/Summary/Keyword: CH1

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Tuning Behavior of (Cyclic Amines + Methane) Clathrate Hydrates and Their Application to Gas Storage (고리형 아민이 포함된 메탄 하이드레이트의 튜닝과 가스 저장 연구)

  • Ki Hun Park;Dong Hyun Kim;Minjun Cha
    • Korean Chemical Engineering Research
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    • v.61 no.3
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    • pp.394-400
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    • 2023
  • In this study, the tuning phenomena, gas storage capacity, and thermal expansion behaviors of binary (cyclopentylamine + CH4) and (cyclopropylamine + CH4) clathrate hydrates were investigated for the potential applications of clathrate hydrates to gas storage. To understand the tuning behaviors of binary (cyclopentylamine + CH4) and (cyclopropylamine + CH4) clathrate hydrates, 13C solid-state NMR spectroscopy was used, and the results confirmed that maximum tuning factors for the binary (cyclopentylamine + CH4) and (cyclopropylamine + CH4) clathrate hydrates were achieved at 0.5 mol% and 1.0 mol% of guest concentration, respectively. The gas storage capacity of binary (cyclopentylamine + CH4) and (cyclopropylamine + CH4) clathrate hydrates were also checked, and the results showed the CH4 capacity of our hydrate systems was superior to that of binary (tetrahydrofuran + CH4) and (cyclopentane + CH4) clathrate hydrates. The synchrotron diffraction patterns of these hydrates collected at 100, 150, 200, and 250 K confirmed the formation of a cubic Fd-3m hydrate. In addition, the lattice constant of clathrate hydrates with cyclopentylamine and methane were larger than that with cyclopropylamine and methane due to the effects of molecular size and shape.

The Effects of Auxin and Casein Hydrolysate on the Growth of Ginseng Hairy Root (인삼모상근의 생장에 미치는 Auxin과 Casein Hydrolysate의 영향)

  • 오승용;박효진;민병훈;양계진;양덕춘
    • Journal of Ginseng Research
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    • v.24 no.3
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    • pp.123-127
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    • 2000
  • In this study, the effects of auxin and casein hydrolysate (CH) on the growth of ginseng hairy root was elucidated. Ginseng hairy root was cultured under light and dark conditions in MS solid and liquid medium with various concentrations of auxin and CH for fifty days. After harvesting the cultures, the fresh and dry weight of cultures were examined, respectively. In the MS solid culture, 1 mg/L of IBA was most effective on the growth of ginseng hairy root under the dark condition, whereas IAA and CH did not affect on the growth of ginseng hairy root. In the MS liquid culture, the growth was maintained regularly by the treatments of IAA and NAA. IBA and CH restrained the growth of ginseng hairy root.

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Methane Oxidation in Landfill Cover Soils: A Review

  • Abushammala, Mohammed F.M.;Basri, Noor Ezlin Ahmad;Irwan, Dani;Younes, Mohammad K.
    • Asian Journal of Atmospheric Environment
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    • v.8 no.1
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    • pp.1-14
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    • 2014
  • Migration of methane ($CH_4$) gas from landfills to the surrounding environment negatively affects both humankind and the environment. It is therefore essential to develop management techniques to reduce $CH_4$ emissions from landfills to minimize global warming and to reduce the human risks associated with $CH_4$ gas migration. Oxidation of $CH_4$ in landfill cover soil is the most important strategy for $CH_4$ emissions mitigation. $CH_4$ oxidation occurs naturally in landfill cover soils due to the abundance of methanotrophic bacteria. However, the activities of these bacteria are influenced by several controlling factors. This study attempts to review the important issues associated with the $CH_4$ oxidation process in landfill cover soils. The $CH_4$ oxidation process is highly sensitive to environmental factors and cover soil properties. The comparison of various biotic system techniques indicated that each technique has unique advantages and disadvantages, and the choice of the best technique for a specific application depends on economic constraints, treatment efficiency and landfill operations.

Fabrication and characterization of silicon-based microsensors for detecting offensive $CH_3SH\;and\; (CH_3)_3N$ gases

  • Lee, Kyu-Chung;Hur, Chang-Wu
    • Journal of information and communication convergence engineering
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    • v.6 no.1
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    • pp.38-42
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    • 2008
  • Highly sensitive and mechanically stable gas sensors have been fabricated using the microfabrication and micromachining techniques. The sensing materials used to detect the offensive $CH_3SH$ and $(CH_3)_3N$ gases are 1 wt% Pd-doped $SnO_2$ and 6 wt% $Al_2O_3$-doped ZnO, respectively. The optimum operating temperatures of the devices are $250^{\circ}C$ and $350^{\circ}C$ for $CH_3SH$ and $(CH_3)_3N$, respectively and the corresponding heater power is, respectively, about 55mW and 85mW. Excellent thermal insulation is achieved by the use of a double-layer membrane: i.e. $0.2{\mu}m$-thick silicon nitride and $1.4{\mu}m$-thick phosphosilicate glass. The sensors are mechanically stable enough to endure the heat cycles between room temperature and $350^{\circ}C$, at least for 30 days.

Semiempirical Calculations of Substituent Effects on the Reactions of Cephem-Like β-Lactam Molecules

  • 이정철;고헌영;창문호;이윤섭
    • Bulletin of the Korean Chemical Society
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    • v.17 no.7
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    • pp.604-607
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    • 1996
  • Semiempirical PM3 MO calculations are applied to estimate both 1-atom (X=S,O,C) and 3-substituent (Y=R, CH2R, SR, CH2SR) effects on the reactions of some 1-atom-replaced and 3-substituted cephem-like β-lactam compounds of thiacephems, oxacephems, and carbacephems. Stabilization energy (SE) of the reaction intermediate for the reaction with a hydroxyl ion can be used to evaluate the facility of a reaction and selected as a chemical reactivity index. With the 1-atom effect only, the SE values obtained imply that thiacephems are generally more reactive than the other two cephem-like molecules and the reactivity order is thiacephems>oxacephems>carbacephems. When it comes to the 3-substituent (Y=R, CH2R, SR, CH2SR) effect, chemical reactivity can be best realized by using a 3-substituted thiacephem molecule capable of giving a resonance-stabilized and electron-rich leaving group after the reaction with a nucleophile. SE values, however, decrease in most cases when an additional intervening ethylene group is present (Y=CH2R, CH2SR). The overall 3-substituent reactivity tendency is SR>CH2SR>R>CH2R.

Anisotropic etching of polysilicon in a $Cl_2/CH_3Br/O_2$ Plasma

  • Yi, Whi-Kun
    • Journal of Korean Vacuum Science & Technology
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    • v.3 no.1
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    • pp.24-29
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    • 1999
  • The characteristic behaviors of CH3Br were examined first for the dry etching of polysilicon in a Cl2/CH3Br/O2 plasma. CH3Br is revealed one of the excellent additive gases to control anisotropy of etching profile and to give no undercutting for various typed of polysilicons. CH3Br acts as a passivation precursor on the side wall in etch cavity by forming polymer-like films such as CHxBry(x+y=1,2). The decrease of etch selectivity due to the reaction if the C-containing species from CH3Br with the surface O atoms of SiO2 was overcome by the addition of O2 into plasma, resulting that the selectivity increased by 2~3 times. According to the results of optical emission signals, CH3Br should be dissociated into several fragments to give more hydrogen atoms than bromine atoms in our helical resonator system.

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Effects of Application of Nitrogen Fertilizers on Methane Emission in a Paddy Soil (논 토양에서 질소비종이 CH4 배출에 미치는 영향)

  • Lee, Kyeong-Bo;Lee, Deog-Bae;Kim, Jong-Gu;Lee, Sang-Bok;Kim, Jae-Duk;Han, Sang-Su
    • Korean Journal of Soil Science and Fertilizer
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    • v.33 no.3
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    • pp.212-219
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    • 2000
  • This study was conducted to investigate methane emission among nitrogen fertilizers in paddy soil(Jeonbug series, occurring on fluvio-alluvial plain). The application rates of rice straw was $5,000kg\;ha^{-1}$ with $110kg\;N\;ha^{-1}$ as chemical fertilizer. It was found that the methane flux tended to be lower in ammonium sulfate than in urea and latex coated urea(LCU). The seasonal variations of the methane emission flux was high during the heading stage of the rice plant. Methane concentration in the soil solution was the highest at 5cm depth, but decreased with upper and lower depth. Methane emission under rice straw application was $0.265g\;m^{-2}\;day^{-1}$ by urea application. $0.207g\;m^{-2}\;day^{-1}$ by ammonium sulfate application, $0.318g\;m^{-2}\;day^{-1}$ by latex coated urea(LCU) application while methane emission under non rice straw application was $0.192g\;m^{-2}\;day^{-1}$ by urea application, $0.165g\;m^{-2}\;day^{-1}$ by ammonium sulfate application, $0.179g\;m^{-2}\;day^{-1}$ by latex coated urea(LCU) application.

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Administration of Alphas1-Casein Hydrolysate Increases Sleep and Modulates GABAA Receptor Subunit Expression

  • Yayeh, Taddesse;Leem, Yea-Hyun;Kim, Kyung-Mi;Jung, Jae-Chul;Schwarz, Jessica;Oh, Ki-Wan;Oh, Seikwan
    • Biomolecules & Therapeutics
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    • v.26 no.3
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    • pp.268-273
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    • 2018
  • Sleep is the most basic and essential physiological requirement for mental health, and sleep disorders pose potential risks of metabolic and neurodegenerative diseases. Tryptic hydrolysate of ${\alpha}_{S1}$-casein (${\alpha}_{S1}-CH$) has been shown to possess stress relieving and sleep promoting effects. However, the differential effects of ${\alpha}_{S1}-CH$ on electroencephalographic wave patterns and its effects on the protein levels of ${\gamma}$-aminobutyric acid A ($GABA_A$) receptor subtypes in hypothalamic neurons are not well understood. We found ${\alpha}_{S1}-CH$ (120, 240 mg/kg) increased sleep duration in mice and reduced sleep-wake cycle numbers in rats. While ${\alpha}_{S1}-CH$ (300 mg/kg) increased total sleeping time in rats, it significantly decreased wakefulness. In addition, electroencephalographic theta (${\theta}$) power densities were increased whereas alpha (${\alpha}$) power densities were decreased by ${\alpha}_{S1}-CH$ (300 mg/kg) during sleep-wake cycles. Furthermore, protein expressions of $GABA_A$ receptor ${\beta}_1$ subtypes were elevated in rat hypothalamus by ${\alpha}_{S1}-CH$. These results suggest ${\alpha}_{S1}-CH$, through $GABA_A$ receptor modulation, might be useful for treating sleep disorders.

A Study on the Reaction Optimization for the Utilization of CO2 and CH4 from Bio-gas (바이오가스에서 CO2/CH4 활용에 관한 반응최적화 연구)

  • KHO, DONGHYUN;CHO, WOOKSANG;BAEK, YOUNGSOON
    • Journal of Hydrogen and New Energy
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    • v.27 no.5
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    • pp.554-561
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    • 2016
  • Depending on the Bio-gas sources, main component gases of $CH_4$ and $CO_2$ are shown to be variously present in amounts. For the anaerobic digester, The concentration of $CH_4$ and $CO_2$ in the gases are 60~70 and 30~35 vol%. For the landfill gas, $CH_4$ and $CO_2$ are 40~60 and 40~60 vol%. For the food wastes, $CH_4$ and $CO_2$ are 60~80 and 20~40 vol%, respectively. In this study, maximum conversion rates of $CO_2$ were obtained from the variety of concentrations of $CH_4$ and $CO_2$ by the catalysts of reforming reactions. Moreover, in order to get maximum producing amount of synthetic gas, experimental studies were performed to optimize the reaction variables. On the basis of $CH_4$, 243 ml, R [$CH_4/(O2+CO_2)$] value were varied from 0.8 to 1.35, in the study of $CH_4$ and $CO_2$ reforming reactions. It was shown that the optimal results were obtained for 1.35 of R value. And also, at $850^{\circ}C$ and 1 atm, the production rate of synthetic gas was 90% and the conversion rates of $CH_4$ and $CO_2$ were higher than 99% and 90%, respectively.

Photoreactivity of $ReH_5$(Cyttp) (Cyttp=Php$(CH_2CH_2CH_2PCy_2)_2)$ with CO, $CO_2\;and\;PMe_3$

  • Lee, Myung-Young;Shin, Dae-Ho;Kim, You-Hyuk
    • Bulletin of the Korean Chemical Society
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    • v.15 no.7
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    • pp.571-576
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    • 1994
  • The photoreactions of $ReH_5(Cyttp)\;(1)\;(Cyttp=PhP(CH_2CH_2CH_2PCy_2)_2)\;with\;CO,\;CO_2\;and\;PMe_3 has been investigated to find the differences in reactivities from those of trismonophosphine analog. Irradiation of 1 under CO, $CO_2$ and excess $PMe_3$ in benzene results in the formation of the complexes, $ReH(CO)_2(Cyttp)\;(2),\;ReH_2({\eta}^2-HCO_2)(Cyttp)\;(3)\;and\;$ReH_3(PMe_3)(Cyttp)$ (4), respectively. The resulting products suggest that photoreactions of $ReH_5(Cyttp)$ proceed by photoextrusion of $H_2$ giving a phototransient species "$ReH_3$(Cyttp)" which can be trapped by CO, $CO_2\;and\;PMe_3$. The structures of 2, 3 and 4 are inferred based on $^1H,\;^{31}P$ NMR and I. R spectroscopy.