• Title/Summary/Keyword: reactions

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A DSMC Technique for the Analysis of Chemical Reactions in Hypersonic Rarefied Flows (화학반응을 수반하는 극초음속 희박류 유동의 직접모사법 개발)

  • Chung C. H.;Yoon S. J.
    • Journal of computational fluids engineering
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    • v.4 no.3
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    • pp.63-70
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    • 1999
  • A Direct simulation Monte-Carlo (DSMC) code is developed, which employs the Monte-Carlo statistical sampling technique to investigate hypersonic rarefied gas flows accompanying chemical reactions. The DSMC method is a numerical simulation technique for analyzing the Boltzmann equation by modeling a real gas flow using a representative set of molecules. Due to the limitations in computational requirements. the present method is applied to a flow around a simple two-dimensional object in exit velocity of 7.6 km/sec at an altitude of 90 km. For the calculation of chemical reactions an air model with five species (O₂, N₂, O, N, NO) and 19 chemical reactions is employed. The simulated result showed various rarefaction effects in the hypersonic flow with chemical reactions.

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Formation and Growth of Atmospheric Aerosols by Water Vapor Reactions in an Indoor Smog Chamber (스모그 챔버에서 수분 반응에 의한 대기 에어로졸의 생성 및 성장)

  • Kim Min Cheol;Bae Gwi-Nam;Moon Kil-Choo;Park Ju-Yeoun
    • Journal of Korean Society for Atmospheric Environment
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    • v.20 no.2
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    • pp.161-174
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    • 2004
  • Aerosol formation and growth by water vapor reactions were investigated in a 2.5 -㎥ indoor smog chamber filled with the unfiltered ambient air. The relative humidity of test ambient air was elevated at 59~64% or 84~88% by adding water vapor. The aerosol number size distribution and the concentrations of $O_3$, NO, NO$_2$, and SO$_2$ were measured during the experiments. The $O_3$ and NO$_2$ gases were well reacted with the water vapor at high relative humidity of 84~88%, and the reaction rates of these gases seemed to be decreased at low relative humidity of 59~64%. The formation and condensational growth phenomena of ambient aerosols by water vapor reactions were observed in a Teflon bag, depending strongly on the initial particle size distribution. The water vapor reactions might be affected by the contents of oxidants produced by photochemical reactions under sunlight.

A Study on the Reaction Mechanism of Selective Epitaxial Growth in $SiH_2Cl_2-H_2-HCl$ System ($SiH_2Cl_2-H_2-HCl$ 시스템에서의 실리콘 선택적 성장에 대한 표면 반응메커니즘 고찰)

  • Kim, Bong-Soo;Han, Seung-Oh;Pak, James Jung-Ho
    • Proceedings of the KIEE Conference
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    • 1998.07d
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    • pp.1288-1290
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    • 1998
  • Three most dominant reactions are adsorption, movement, and desorption of $SiCl_2$ on silicon surface. $SiCl_2$ plays a key role in these dominant reactions. In this paper, surface reactions of $SiH_2Cl_2-H_2-HCl$ system are investigated and few dominant reactions were identified. An equation for Si net growth rate is derived from the analysis of these reactions and it is compared with experimental results of Bolem and Classen.

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Paradoxical Reactions following Intravenous Midazolam in Patients with Severe Anxiety for Dental Treatment -A Case Report- (치과 치료에 대한 심한 공포가 있는 환자들에서 미다졸람 정주 후 나타난 기이반응 -증례보고-)

  • O, Se-Ri
    • Journal of The Korean Dental Society of Anesthesiology
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    • v.9 no.1
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    • pp.30-35
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    • 2009
  • Intravenous midazolam has been frequently used for the relief of anxiety in dental treatment. This is likely the result of the sedative and anterograde amnestic properties of midazolam that are mediated through $\gamma$-Aminobutyric acid agonism. Unfortunately, Paradoxical reactions to midazolam include agitation, talkativeness, confusion, disinhibition, aggression,violent behavior, act of self-injury and need for restraints. These occur in less than 1% of all patients receiving midazolam, may occur at variable times after administration and are difficult to predict and diagnose. Two women with severe anxiety for dental treatment experienced paradoxical reactions associated with the use of intravenous midazolam. We are reviewed the management and prevention of paradoxical reactions and its different etiology.

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Effects of Competition between Phase Separation and Ester Interchange Reactions on the Phase Behavior in a Phase-Separated Immiscible Polyester Blend: Monte Carlo Simulation

  • Youk, Ji-Ho;Jo, Won-Ho
    • Fibers and Polymers
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    • v.2 no.2
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    • pp.81-85
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    • 2001
  • The effects of rate of phase separation to ester interchange reactions and the repulsive pair interaction energy on the phase behavior in a phase-separated immiscible polyester blend are investigated using a Monte Carlo simulation method. The time evolution of structure factor and the degree of randomness are monitored as a function of homogenization time. When the phase separation is dominant over ester interchange reactions, the domain size slowly increases with homogenization time. However, when the pair interaction becomes less repulsive, the domain size does not significantly change with homogenization time. On the other hand, when ester interchange reactions are dominant over the phase separation, the homogenization proceeds without a change in the domain size. The higher the extent of phase separation, the lower the increasing rate of the DR. However, when the phase separation is sufficiently dominant, the effect of the extent of phase separation on the increasing rate of the degree of randomness become less significant.

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Pd-Catalyzed Substitution Reactions with Organoindium Reagents in situ Generated from Indium and Allyl or Propargyl Halides

  • Lee, Phil-Ho;Shim, Eun-Kyong;Lee, Koo-Yeon;SeoMoon, Dong;Kim, Sun-Dae
    • Bulletin of the Korean Chemical Society
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    • v.26 no.1
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    • pp.157-160
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    • 2005
  • Allylindium and propargylindium reagents in situ generated from the reactions of indium with allyl halides and propargyl halides could participate as nucleophiles in Pd-catalyzed substitution reactions of allyl carbonates to produce 1,5-dienes and 1,5-enynes in good yields. $\beta$-Hydride elimination products were produced in case of carbonates having $\beta$-hydrogens. Because organoindium reagents obtained from allyl or propargyl halides and indium have previously not been used to Pd-catalyzed allylic and propargylic substitution reactions, these results should provide more opportunities for the development of new C-C bond forming reactions.

Linking Maternal Emotion Socialization to Boys' and Girls' Emotion Regulation in Korea

  • Song, Ju-Hyun;Trommsdorff, Gisela
    • Child Studies in Asia-Pacific Contexts
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    • v.6 no.2
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    • pp.47-57
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    • 2016
  • This study investigated whether Korean mothers' emotion socialization beliefs are related to emotional functioning in children differing across gender. We interviewed Korean mothers (N = 100) of first graders (55 boys; 45 girls) about their sensitivity, their reactions to children's distress, and children's emotion regulation. Two components of emotion regulation were distinguished: regulation and negativity. Results revealed that mothers' proactive sensitivity and their supportive reactions were related to their children's regulation, whereas unsupportive reactions were related to children's negativity. Child gender moderated the associations between mothers' socialization beliefs and children's emotion regulation: mothers' proactive sensitivity was more strongly associated with competent regulation in girls than in boys. Mothers' unsupportive reactions were related to increased negativity only in girls. Results are discussed from a cultural perspective, focusing on gender differences in the links between maternal socialization and children's emotional outcomes in Korea.

The Measurement of Tranfer Enthalpy in Mixed Solvent (Part 2) Solvent Effects on Nucleophilic Substitution Reactions of Ethyl and 2-Phenylethyl Benzenesulfonates

  • Heo, Cheol;Lee, Hae Hwang;Lee, Ik Chun
    • Bulletin of the Korean Chemical Society
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    • v.16 no.1
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    • pp.53-58
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    • 1995
  • Heats of solution of aniline (AN), benzylamine (BA), ethyl-(EBS) and 2-phenylethyl benzenesulfonates (PEB) are calorimetrically measured in acetonitrile-methanol mixtures at 25.0 $^{\circ}C$. The activation parameters, ${\Delta}H^{\neq}$, ${\Delta}S^{\neq}$ and ${\Delta}G^{\neq}$, are determined for the reactions of EBS and PEB with AN and BA using the kinetic data at three temperatures. Calorimetric transfer enthalpies of initial state, ${\delta}H_t^{0{\rightarrow}x})$(IS), and kinetically derived activation enthalpies, ${\delta}\;{\Delta}H^{\neq}$, in the MeCN-MeOH mixtures are combined to determine the transfer enthalpies of transition state, ${\delta}H_t^{0{\rightarrow}x})$(TS); ${\delta}H_t^{0{\rightarrow}x})$(IS) = ${\delta}{\Delta}H^{\neq}\;+\;{\delta}H_t^{0{\rightarrow}x}$(IS) The preferential solvation of anionic charge in the TS predicts a loose TS with a greater degree of bond cleavage for the reactions of PEB than for EBS, and also for the reactions with BA compared to the reactions with AN.