• 대한환경공학회지
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• 제28권3호
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• pp.323-328
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• 2006

본 논문의 목적은 부채꼴방전(GlidArc) 플라즈마 개질을 이용하여 프로판으로부터 카본블랙의 형성이 없는 합성가스 생산을 위한 개질특성과 최적 운전조건을 연구하였다. 또한 수소 생산 및 프로판 전환율을 항상시키기 위해 반응기 내의 촉매반응 영역에 13 wt%의 니켈촉매를 충진하여 수증기 몰 비, 이산화탄소 몰 비, 입력 전력, 주입 유량 변화의 변수별 연구를 수행하였다. 그 결과, 수증기 몰 비, 이산화탄소 몰 비, 입력 전력, 주입 유량이 각각 1.86, 0.48, 1.37 kW, 14 L/min일 때 프로판 전환율이 62.6%로 최적이었다. 위의 조건에서 합성가스의 건가스 기준에 농도는 $H_2\;44.4%,\;CO\;18.2%,\;CH_4\;11.2%,\;C_2H_2\;2.0%,\;C_3H_6\;1.6%,\;C_2H_4\;0.6%,\;C_3H_4$ 0.4%이며, 이산화탄소 전환율은 29.2%, 합성가스 내의 $H_2/CO$ 농도 비는 2.4이다.

• 한국표면공학회지
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• 제29권6호
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• pp.648-653
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• 1996

Hydrogenated amorphous carbon(a-C:H) films are prepared by rf plasma CVD in a $CH_4$ source gas system diluted with Ar of $H_2$. The spectra of emissive and reactive species in the plasma are detected using in stiu optical emission spectroscopy. Inaddition, the relationship between the film properties which can be varied by the deposition parameters and the Raman spectra is studied. In the $CH_4/H_2$ gas system, the emission intensities of CH and $H \tau$ decrease and those of $H \alpha$, $H \beta$, $C_2$ and Ar increase with increasing $H_2$ concentration, The formation of $C_2$ and CH in the $CH_4/Ar/H_2$ gas system is greatly suppressed by hydrogen addition and the excess of hydrogen addition is found to form graphite structure. The $C_2$ formation in the gas phase enhances a-C:H film formation.

• 한국재료학회지
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• 제28권2호
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• pp.75-81
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• 2018

An ultra-high temperature ceramic, tantalum carbide, has received much attention for its favorable characteristics: a superior melting point and chemical compatibility with carbon and other carbides. One drawback is the high temperature erosion of carbon/carbon (C/C) composites. To address this drawback, we deposited TaC on C/C with silicon carbide as an intermediate layer. Prior to the TaC deposition, the $TaCl_5-C_3H_6-H_2$ system was thermodynamically analyzed with FactSage 6.2 and compared with the $TaCl_5-CH_4-H_2$ system. The results confirmed that the $TaCl_5-C_3H_6-H_2$ system had a more realistic cost and deposition efficiency than $TaCl_5-CH_4-H_2$. A dense and uniform TaC layer was successfully deposited under conditions of Ta/C = 0.5, $1200^{\circ}C$ and 100 torr. This study verified that the thermodynamic analysis is appropriate as a guide and prerequisite for carbide deposition.

• Bulletin of the Korean Chemical Society
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• 제14권1호
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• pp.113-117
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• 1993

Good yield synthetic routes for the production of new B-alkyl-dithiaborane clusters are reported. The syntheses of the B-alkyl-dithiaboranes are based on the use of Fischer-type carbene reagents to activate the B-H bonds of dithiaborane for alkyl-addition reactions and are the first examples of transition-mediated reactions of dithiaborane to be reported. Thus, reactions employing arachno-$S_2B_7H_8$- and $(CO)_5M{C(R_1)R_2}$ (M = Cr, W; $R_1 = CH_3,\;C_6H_5;\; R_2 = OCH_3,\;SC_6H_5)$ were found to yield the intermidiate anions I, $[(CO)_5M{C(R_1)R_2S_2B_7H_8}]^-$, which upon protonation gave the corresponding neutral, air-sensitive cluster arachno-4-$RCH_2-6,8-S_2B_7H_8(R=CH_3,\;IIa;\;C_6H_5,\;IIb)$ range from 30 to 35% yield. Complexes IIa and IIb are isoelectronic with arachno-6,8-$S_2B_7H_9$ and, on the basis of the spectroscopic data, are proposed to adopt a similar arachno cage geometry in which an $RCH_2$ units are substituted to 4 position boron atom of the arachno-6,8-$S_2B_7H_9$.

• 동력기계공학회지
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• 제17권4호
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• pp.58-63
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• 2013

This paper presents the new cascade liquefaction cycles using $CO_2-C_2H_6-N_2$ and $CO_2-N_2O-N_2$. The performance of the cascade liquefaction cycles with respect to temperature differences in the LNG heat exchangers is analyzed using HYSYS software and then compared the performance of these cycles with phillips optimized cascade liquefaction cycle. The coefficient of performance of the new liquefaction cycles considered in this study decreases with the temperature differences in the LNG heat exchangers, but the compressor work, expander work and heat capacity in the LNG heat exchanger increases, respectively. From the comparison of performance of three cycles, the cascade liquefaction cycles using $CO_2-C_2H_6-N_2$ showed the highest COP. And the cycles using $CO_2-C_2H_6-N_2$ and $CO_2-N_2O-N_2$ presented the second and third highest COP, respectively. In the view of performance, the optimized cascade liquefaction cycle using $C_3H_8-C_2H_4-C_1H_4$ yields much better COP. But, in the environment view, it is found that the cascade liquefaction cycle using $CO_2-C_2H_6-N_2$ shows favorable characteristics.

• Toxicological Research
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• 제16권3호
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• pp.179-185
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• 2000

Zinc is known to generate reactive oxygen species (ROS) including superoxide anion and hydrogen peroxide ($H_2O_2$), which eventually contribute to cytotoxicity in a variety of cell types. Here in, we demonstrated that zinc decreased the viability of C6 glial cells in a time and dose-dependent manner, which was revealed as apoptosis characterized by ladder-pattern fragmentation of genomic DNA. chromatin condensation and DNA fragmentation in Hoechst dye staining. Zinc-induced apoptosis of C6 glial cells was prevented by the addition of catalase and antioxidants including reduced glutathione (GSH), N-acetyl-L-cysteine (NAC) and pyrrolidinedithiocarbamate (PDTC). Wefurther confirmed that zinc decreased intrac-ellular levels of GSH and generated $H_2O_2$in C6 glial cells. Moreover, antioxidants also decreased the generation of zinc-induced $H_2O_2$ in C6 glial cells. These data indicated that zinc-induced the apoptotic death of C6 glial cells via generation of reactive oxygen species such as $H_2O_2$.

• Applied Biological Chemistry
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• 제1권
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• pp.43-47
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• 1960

1). By means of the F.H. Allene and James Allenes method of the ${\alpha}-methylindole$ synthesis, 2-methylindole was prepared with the Acetyl-o-toluidine and $NaNH_2$. yield; 88%, mp. $56.5{\sim}57^{\circ}C$. 2). 23.7 gr of 3-(-Nitro-1-phenylethyl)-2-melthylindole was prepared with 0.1 mol. of the 2-methylindole and 0.1 mol. of the ${\beta}-Nitrostyrene$. yield: 84.6%, mp. $104{\sim}105^{\circ}C$. 3). Analytical results. Calcd. for $C_{17}H_{16}N_2O_2$: C, 72.84; H, 5.63; N, 9.99. Found: C, 72.62; H, 5.63; N, 9.79.

• 대한화학회지
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• 제30권5호
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• pp.441-448
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• 1986

몰리브덴산암모늄 수용액에서 적절한 살리실알데히드의 메탄올 혼합용액으로부터 디옥소비스(치환-살리실알데히다토) 몰리브덴늄(VI), $MoO_2(X-sal)_2(X=H,\;5-CH_3)$착물을 합성하고, 이들 각각의 화합물과 다양한 일차아민의 반응에 의하여 디옥소비스(치환-살리실알디미나토) 몰리브덴늄(VI)착물, $MoO_2(X-sal-N-R)_2,\;(R=C_6H_5,\;p-F-C_6H_4,\;m-Cl-C_6H_4,\;p-I-C_6H_4$ 및 $p-C_2H_5-C_6H_4)$을 합성하였다. 이들 착물은 모두 $900{\sim}940cm^{-1}$ 부근에서 ${\upsilon}_{Mo}=0$에 기인한 두 개의 강한 흡수띠가 관찰되었고, 핵자기공명스펙트럼에서 N=CH양성자에 대한 한 개의 시그날이 8.9ppm부근에서 나타났다. 이는 이들 착물이 $cis-MoO_2$기를 가진 6배위팔면체 착물임을 나타낸다. 질량분석의 결과로부터, $MoO_2$ : ligand의 결합비가 1:2임을 확인하였고, $MoO_2(5-CH_3-sal-N-R)_2$착물에 대한 분해과정을 조사하였다. 전자흡수스펙트럼에서 $N{\to}Mo$와 $O{\to}Mo$에 해당하는 전하이동전이는 $29,000cm^{-1}$과 $32,000cm^[-1}$부근에서 각각 일어났다. 한편, 디메틸포름아미드에서 측정한 이들 착물에 대한 몰전도도로부터 이들 착물이 비이온성 물질임을 확인하였다.

• Bulletin of the Korean Chemical Society
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• 제18권2호
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• pp.218-221
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• 1997

When phenylation of styrene was carried out in the presence of Pd(OAc)2 and PPh3 in benzene, trans-stilbene was obtained in good yield (566%) with high selectivity (98%) under mild condition (55 ℃, 50 psi O2, 20 h). Since trans-stilbene could be produced not only from benzene but also from phenyl group of PPh3 by migration of its phenyl group to Pd, the competitiveness of benzene and the migratory aptitude of aryl group of triarylphosphine toward styrene has been investigated with various phosphines (PR3: P(p-C6H4CH3)3, P(p-C6H4OCH3)3, P(p-C6H4F)3, P(p-C6H4Cl)3, P(C6H5)3, P(C6H11)3, P(OC4H9n)3, P(CH2C6H5)3 and P(C6F5)3). The yield and selectivity toward trans-stilbene are increased as the basicity of the phosphines increases. The composition of arylated olefin from arylphosphine, in turn, increases as the electronegativity of the substituent on the aryl group of arylphosphines increases.

• Molecules and Cells
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• 제22권2호
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• pp.220-227
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• 2006

Oxidative alteration of mitochondrial cytochrome c has been linked to disease and is one of the causes of proapoptotic events. We have investigated the modification of cytochrome c by $H_2O_2$. When cytochrome c was incubated with $H_2O_2$, oligomerization of the protein increased and the formation of carbonyl derivatives and dityrosine was stimulated. Radical scavengers prevented these effects suggesting that free radicals are implicated in the $H_2O_2$-mediated oligomerization. Oligomerization was significantly inhibited by the iron chelator, deferoxamine. During incubation of deoxyribose with cytochrome c and $H_2O_2$, damage to the deoxyribose occurred in parallel with the release of iron from cytochrome c. When cytochrome c that had been exposed to $H_2O_2$ was analyzed by amino acid analysis, the tyrosine, histidine and methionine residues proved to be particularly sensitive. These results suggest that $H_2O_2$-mediated cytochrome c oligomerization is due to oxidative damage resulting from free radicals generated by a combination of the peroxidase activity of cytochrome c and the Fenton reaction of free iron released from the oxidatively-damaged protein.