• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.284-284
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• 2012

In this study, $V_2O_5/TiO_2$ catalyst was measured reactivity of ethanol when vanadia ratio was increasing. First, $V_2O_5/TiO_2$ catalyst was prepared to the increasing vanadia ($VO_x$) ratio as 0.2, 1, 10 wt%. And we were used X-ray diffraction (XRD), then not appear markedly peak to pure vanadia about XRD analysis. So we were decided vanadia that was evenly dispersed on $TiO_2$. Result about temperature-programmed reduction (TPR) analysis was obtained 3 reactions that was dehydrogenationfrom obtained to acetaldehyde, dehydration from obtained to ethylene, condensation from obtained to diethyl ether. If vanadia ratio was increasing in $V_2O_5/TiO_2$, reactions temperature of ethanol was known lower. And condensation into diethyl ether is quenched away with increasing vanadia loading. In addition, competition between reductive dehydration and oxidative dehydrogenation occurs, while the selectivity toward dehydrogenation is favored with increasing vanadia loading.

• Bulletin of the Korean Chemical Society
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• 제15권11호
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• pp.985-990
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• 1994

Cross-interaction constants, ${\rho}^e_{XY}$, ${\rho}_{YZ}$ and ${\rho}_{XZ}$ are defined using observed rate constant, k_N=(k_1/k_{-1})k_2=Kk_2$, for the stepwise carbonyl addition reactions involving the rate-limiting breakdown of a tetrahedral intermediate $(T^{\pm})$. Abundant experimental evidence in the literature enables us to determine signs for the three constants for such mechanism, ${\rho}^e_{XY}$>0, ${\rho}_{YZ}$<0 and ${\rho}_{XZ}$0. These are in contrast to those for the concerted $S_N2$ mechanism, ${\rho}_{XY}$<0, ${\rho}_{YZ}$>0 and ${\rho}_{XZ}$, and provide useful mechanistic criteria. In the light of these criteria, mechanisms of some nucleophilic reactions of carbonyl compounds are re-examined.

• Bulletin of the Korean Chemical Society
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• 제16권12호
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• pp.1203-1208
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• 1995

Theoretical studies of the effect of the nonleaving group (RY) on the breakdown mechanism of the tetrahedral anionic intermediate, T-, formed by the addition of a less basic phenoxide nucleophile (X) to phenyl benzoates with a more basic phenoxide leaving group (Z) have been carried out using the PM3 MO method. The identity acyl transfer reactions (X=Z) are facilitated by an electron-withdrawing RY whereas they are inhibited by an electron-donating RY group. The results of non-identity acyl transfer reactions indicate that a more electron-donating RY group leads to a greater lowering of the higher barrier, TS2, with a greater degree of bond cleavage, and a greater negative charge development on the phenoxide oxygen atom, whereas the opposite is true for a more electron-withdrawing RY group, i.e., leads to a greater lowering of the lower barrier, TS1. The results provide theoretical basis for the signs of ρXY(>0) and ρYZ(<0) observations.

• Nuclear Engineering and Technology
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• 제51권3호
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• pp.915-921
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• 2019

Radiation damage due to neutrons has been calculated in Ni-based alloys in Wolsong CANDU reactor environments. Two damage parameters are considered: displacement damage, and transmutation gas production. We used the SPECTER and SRIM computer codes in quantifying radiation damage. In addition, damage caused by Ni two-step reactions was considered. Estimations were made for the annulus spacers in a CANDU reactor that are located axially along a fuel channel and made of Inconel X-750. The calculation results indicate that the transmutation gas production from the Ni two-step reactions is predominant as the effective full power year increases. The displacement damage due to recoil atoms produced from Ni two-step reactions accounts for over 30% out of the total displacement damage.

• Bulletin of the Korean Chemical Society
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• 제16권3호
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• pp.252-256
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• 1995

Semiempirical MO calculations using the PM3 method are performed on the reactions of acetate esters with substituted phenolate anions. The mechanistic change from rate-limiting formation to breakdown of the anionic intermediate is shown to occur in the gas-phase, especially for meta-nitrophenyl acetate. However the mechanistic change-over takes place at a lower basicity ($pK_0$) of the anion nucleophile than found for the corresponding formate. This lowering of $pK_0$ has been ascribed to the electron donating effect of the methyl group in the acetate. For the reactions involving rate-limiting breakdown of the intermediate, the large Bronsted coefficients, ${\beta}_X({\beta}_{nuc})$, are expected in general, but the magnitude increases to a larger value and the pK0 is lowered accordingly, when an electron-donating nonleaving group, like $CH_3$, is present. This type of nonleaving group effect provides a necessary condition for the carbonyl addition-elimination mechanism with rate-limiting breakdown of the intermediate.

• Clinical and Experimental Pediatrics
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• 제52권4호
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• pp.499-503
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• 2009

요오드성 조영제는 즉각적인 부작용과 지연성 부작용을 일으킬 수 있다. 저자들은 컴퓨터 단층 촬영을 위해 요오드성 조영제인 iopromide ($Ultravist^{(R)}$)를 사용하고 2일 뒤에 전신에 반점 구진성 반점과 발열이 반복적으로 발생한 환아를 경험하였다. 이 환아에서 피부단자시험, 피내반응검사, 첩포검사를 포함한 피부반응검사를 시행하여 $Ultravist^{(R)}$에 지연성 반응임을 확인하고 다른 조영제인 ioversol ($Optiray^{(R)}$), iohexol ($Iobrix^{(R)}$), iobitridol ($Xenetix^{(R)}$) 에도 교차반응이 있음을 확인하였기에 보고하는 바이다.

• Natural Product Sciences
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• 제12권3호
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• pp.144-149
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• 2006

The immediate-type allergic reaction (anaphylaxis) is involved in many allergic diseases such as asthma, allergic rhinitis, and sinusitis. The discovery of drugs for the treatment of immediate-type allergic diseases is a very important subject in human health. In this study, we investigated the effect of Rubus coreanus Miq.(Rosaceae) unripe fruits (RCF) on mast cell-mediated allergic reaction and inflammatory cytokine secretion. RCF inhibited compound 48/80-induced systemic reactions in mice. RCF attenuated immunoglobulin (Ig) E-mediated local allergic reactions. In addition, RCF dependently reduced histamine release from rat peritoneal mast cells local allergic reactions. In addition, RCF dependently reduced histamine release from rat peritoneal mast cells activated by compound 48/80 or IgE. Furthermore, RCF decreased the phorbol 12-myristate 13-acetate plus calcium ionophore A23187-stimulated tumor necrosis factor $(TNF)-{\alpha}$ and interleukin (IL)-6 secretion in human mast cells. Our findings provide evidence that RCF inhibits mast cell-derived immediate-type allergic reactions.

• Bulletin of the Korean Chemical Society
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• 제24권1호
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• pp.15-16
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• 2003

• 한국재료학회지
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• 제12권11호
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• pp.889-893
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• 2002

The reactions of $Cu/Ti/SiO_2$ structures at temperatures ranging from 200 to $700^{\circ}C$ have been studied for various Ti thicknesses. The reaction products initially formed, at around $300^{\circ}C$, were a series of Cu-Ti intermetallics ($Cu_3$Ti/CuTi) with the oxygen dissolved in the Ti moving from the compounds into the remaining unreacted Ti. At $500^{\circ}C$, the $Cu_3$Ti was converted into Cu-rich intermetallics, $Cu_4$Ti, which grew at the expense of the CuTi due to the increased oxygen content in the Ti. In addition, the outdiffusion of Ti, to the Cu surface, and the $Ti-SiO_2$ reactions, caused an abrupt increase in the oxygen content in the Ti layer, which placed thermodynamic restraints on further Ti reactions. Furthermore, thinner Ti layers showed a higher increasing rate of oxygen accumulation for the same consumption of Ti, which led to significantly reduced Ti consumption. The $SiO_2$ film under the Ti diffusion barrier was more easily destroyed with increasing Ti thickness.

• Bulletin of the Korean Chemical Society
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• 제34권7호
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• pp.2099-2104
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• 2013

We present here an efficient and simple method for preparation of highly active Pd heterogeneous catalyst (CNT-Pd), specifically by reaction of dichlorobis(triphenylphosphine)palladium ($Pd(PPh_3)_2Cl_2$) with thiolated carbon nanotubes (CNTs). The as-prepared CNT-Pd catalysts demonstrated an excellent catalytic activity for the carbon-carbon (C-C) cross-coupling reactions (i.e. Suzuki, Stille, and decarboxylative coupling reactions) under mild conditions. The CNT-Pd catalyst could easily be removed from the reaction mixture; additionally, in the decarboxylative coupling of iodobenzene and phenylpropiolic acid, it showed a six-times recyclability, with no loss of activity. Moreover, once its activity had decreased by repeated recycling, it could easily be reactivated by the addition of phosphine ligands. The remarkable recyclability of the decarboxylative coupling reaction is attributable to the high degree of dispersion of Pd catalysts in CNTs. Aggregation of the Pd catalysts is inhibited by their strong adhesion to the thiolated CNTs during the chemical reactions, thereby permitting their recycling.