• Title, Summary, Keyword: {\gamma})reaction$

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Reactions of $\gamma$,$\gamma$,$\gamma$-Trichloroethylidene-m-Nitroacetophenone with Hydrazines ($\gamma$,$\gamma$,$\gamma$-Trichloroethylidene-m-Nitroacetophenone과 Hydrazine 들의 반응)

  • Youn Young Lee;Suk Zu Song
    • Journal of the Korean Chemical Society
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    • v.17 no.1
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    • pp.25-30
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    • 1973
  • 2,6-Disubstituted-3-pyridazinones were synthesized by the reactions of $\gamma$,$\gamma$,$\gamma$-trichloroethylidene-m-nitroacetophenone with phenylhydrazine and substituted phenylhydrazines, and hydrazone was isolated as an intermediate from the reaction with 2, 4-dinitrophenylhydrazine. From the reaction with hydrazine hydrate 3-(m-nitrophenyl)-5-trichloromethyl-2-pyrazoline was obtained in good yield. The effect of substituents on phenyl group in the reaction of $\gamma$,$\gamma$,$\gamma$-trichloroethylidene-m-nitroacetophenone with substituted phenylhydrazines was also discussed.

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SEPARATION OF GAMMA-RAYS PRODUCTION FROM $^{13}C(p,\;{\gamma})^{14}N,\;^{14}N({\gamma},\;{\gamma})^{14}N$ REACTIONS USING DOPPLER SHIFT EFFECT

  • Kim, Y.K.;Ha, J.H.;Youn, M.;Han, S.H.;Chung, C.E.;Moon, B.S.
    • Journal of Radiation Protection and Research
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    • v.26 no.3
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    • pp.287-290
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    • 2001
  • The 9.17MeV gamma-rays from the $^{13}C(p,\;{\gamma})^{14}N,\;^{14}N({\gamma},\;{\gamma})^{14}N$ reactions were measured. The incident 9.17MeV gamma-ray was produced from the $^{13}C(p,\;{\gamma})^{14}N$ reaction at Ep=1.75MeV resonance. The 1.75MeV proton beam was accelerated using the 3MV SNU-AMS Tandetron and 1.7MV KIGAM Tandem accelerators. The enriched 13C target was $121{\mu}g/cm^2$ self-supporting foil, and we used liquid nitrogen as a resonant absorption target. We used a HP-Ge detector with 30% efficiency and less 2keV energy resolution. We developed new method to detect the scattered 9.17MeV gamma-ray from the nitrogen target by using the energy difference between the Doppler shifted gamma-ray from the $^{13}C(p,\;{\gamma})^{14}N$ reaction and the resonant absorbed and rescattered gamma-ray from the $^{14}N({\gamma},\;{\gamma})^{14}N$ reaction.

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Dependence of an Interfacial Diels-Alder Reaction Kinetics on the Density of the Immobilized Dienophile: An Example of Phase-Separation

  • Min, Kyoung-Mi;Jung, Deok-Ho;Chae, Su-In;Kwon, Young-Eun
    • Bulletin of the Korean Chemical Society
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    • v.32 no.5
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    • pp.1679-1684
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    • 2011
  • Interfacial reactions kinetics often differ from kinetics of bulk reactions. Here, we describe how the density change of an immobilized reactant influences the kinetics of interfacial reactions. Self-assembled monolayers (SAMs) of alkanethiolates on gold were used as a model interface and the Diels-Alder reaction between immobilized quinones and soluble cyclopentadiene was used as a model reaction. The kinetic behavior was studied using varying concentrations of quinones. An unusual threshold density of quinones (${\Gamma}_c$ = 5.2-7.2%), at which the pseudo-first order rate constant started to vary as the reaction progressed, was observed. This unexpected kinetic behavior was attributed to the phase-separation phenomena of multi-component SAMs. Additional experiments using more phase-separated two-component SAMs supported this explanation by revealing a significant decrease in ${\Gamma}_c$ values. When the background hydroxyl group was replaced with carboxylic or phosphoric acid groups, ${\Gamma}_c$ was observed at below 1%. Also, more phase-separated thermodynamically controlled SAMs produced a lower critical density (3% < ${\Gamma}_c$ < 4.9%) than that of the less phaseseparated kinetically controlled SAMs (6.5% < ${\Gamma}_c$ < 8.9%).

Synthesis and Monomer Reactivity Ratio of PNIPAAM-PMMA Random Copolymer (PNIPAAM-PMMA Random Copolymer의 합성 및 단량체 반응성비 측정)

  • 이창배;조창기
    • Polymer Korea
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    • v.24 no.2
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    • pp.168-173
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    • 2000
  • Radical copolymerization of N-isopropylacrylamide (NIPAAM) with methyl methacrylate (MMA) was carried out in 1,4-dioxane using 2,2'-azobisisobutyronitrile (AIBN). To investigate the reactivity ratios of NIPAAM and MMA at different reaction temperatures, the copolymerization was allowed to proceed to low conversion (less than 10 wt%), and the reaction temperatures were 50, 60, and 7$0^{\circ}C$. The monomer reactivity ratios of NIPAAM and MMA were estimated by the graphical methods according to the Finemann-Ross equation. The ${\gamma}$$_1$ and ${\gamma}$$_2$ values for NIPAAM-MMA were 0.259 and 2.782 at 5$0^{\circ}C$, 0.271 and 2.819 at 6$0^{\circ}C$, and 0.286 and 2.915 at 7$0^{\circ}C$, respectively. As the reaction temperature increased, the ${\gamma}$$_1$ and ${\gamma}$$_2$ values increased. The activation energy difference was estimated by comparing the reactivity ratios at different reaction temperatures.

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Measuring one Nucleon Transfer Reaction 24Mg(p, d) 23Mg for Astrophysical Reaction Rates

  • Lee, E.J.;Chae, K.Y.
    • Journal of the Korean Physical Society
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    • v.71 no.11
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    • pp.758-763
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    • 2017
  • The level structure of a radionuclide $^{23}Mg$ has been studied by using the $^{24}Mg(p,\;d)^{23}Mg$ one nucleon transfer reaction measurement for the astrophysical $^{19}Ne({\alpha},\;{\gamma})^{23}Mg$ reaction rate. A 41 MeV proton beam was produced and accelerated at the 25 MV tandem accelerator of the Holifield Radioactive Ion Beam Facility of the Oak Ridge National Laboratory in the United States. The beam particles impinged on an isotopically-enriched $^{24}Mg$ solid target. Angular distributions of recoiling deuterons were extracted by using a large area silicon strip detector array. By comparing the experimentally-obtained angular distributions with zero range distorted wave Born approximation calculations, spins and parities of three energy levels of $^{23}Mg$ could be constrained for the first time, which is very important information needed to understand the $^{19}Ne({\alpha},\;{\gamma})^{23}Mg$ reaction rate.

A Study on the Sulfur-Resistant Catalysts for Water Gas Shift Reaction III. Modification of $Mo/γ-Al_2O_3$ Catalyst with Iron Group Metals

  • Park, Jin Nam;Kim, Jae Hyeon;Lee, Ho In
    • Bulletin of the Korean Chemical Society
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    • v.21 no.12
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    • pp.1233-1238
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    • 2000
  • $Mo/{\gamma}-Al_2O_3catalysts$ modified with Fe, Co, and Ni were prepared by impregnation method and catalytic activity for water gas shift reaction was examined. The optimum amount of Mo loaded for the reaction was 10 wt% $MoO_3$ to ${\gamma}-Al_2O_3.$ The catalytic activity of $MoO_3/{\gamma}-Al_2O_3was$ increased by modifying with Fe, Co, and Ni in the order of Co${\thickapprox}$ Ni > Fe. The optimum amounts of Co and Ni added were 3 wt% based on CoO and NiO to 10 wt% $MoO_3/{\gamma}-Al_2O_3$, restectively. The TPR (temperature-programmed reduction) analysis revealed that the addition of Co and Ni enganced the reducibility of the catalysts. The results of both catalytic activity and TPR experiments strongly suggest that the redox property of the catalyst is an important factor in water gas shift reaction on the sulfided Mo catalysts, which could be an evidence of oxy-sulfide redox mechanism.

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Response Function of HPGe Detector using $^{23}Na$(p, $\gamma$)$^{24}Mg$ and $^{27}Al$(p, $\gamma$)$^{28}Si$ Reaction ($^{23}Na$(p, $\gamma$)$^{24}Mg$$^{27}Al$(p, $\gamma$)$^{28}Si$반응을 이용한 HPGe 검출기의 응답함수)

  • Park, Sang-Tae
    • Journal of Radiation Protection and Research
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    • v.35 no.2
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    • pp.85-90
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    • 2010
  • In the present work, peak relative efficiency for the energy was obtained and response function was worked out. This study was carried out using the high resolution high efficiency HPGe detector(diameter 78.7 mm, length 86.5 mm) and NaI(Tl) detector for anti-compton. The anti-coincidence of the signals from the two detectors could be used to lessen the Compton effect signal; thus, the $\gamma$-ray energy resolution could be improved. The $\gamma$-ray spectrum was measured at $55^{\circ}$ to the direction of the incident proton beam. Reaction spectrum was obtained from the $^{23}Na$(p, $\gamma$)$^{24}Mg$ reaction at $E_p$ = 1424 keV and $^{27}Al$(p, $\gamma$)$^{28}Si$ reaction at $E_p$ = 992 keV. To accelerate the incident proton which creates the (p, $\gamma$) capture reaction, the 3 MeV Pelletron accelerator at the Tokyo Institute of Technology was used. Response function was worked out by a noble technique. We worked out a response function from 1.2 to 9.4 MeV at intervals of 0.75 MeV.

Chlorination of Phenyl Derivatives : Chlorination of ethyl -${\alpha},{\beta}-dichloro-{\beta}$-phenyl propionate under gamma ray irradiation (芳香族 誘導體의 염素化反應 Ethyl-${\alpha},{\beta}-dichloro-{\beta}$-phenyl propionate의 gamma 線 鹽素化反應)

  • Kim, You-Sun;Kim, Ki-Soo
    • Journal of the Korean Chemical Society
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    • v.12 no.2
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    • pp.55-60
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    • 1968
  • Chlorination of aromatic derivatives under UV light and ${\gamma}$-ray irradiation was studied. Ethyl ${\alpha} ,{\beta} -dichloro-{\beta}$-phenyl propionate gave the p-chlorophenyl derivatives when chlorination was done under UV light. The same type of the product was obtained in the reaction where the mole ratio of the ester and chlorine was 1 to 2 and the chlorination was done under ${\gamma}$-ray irradiation. When the mole ratio of the ester and chlorine was 1 to 8, the chlorination reaction under ${\gamma}$-ray irradiation gave a poly-chlorinated derivatives which was identified as a side chain chlorinated p-chlorophenyl derivatives. Ethyl ${\alpha} ,{\beta} -dichloro-{\beta}$-(p-chlorophenyl) propionate gave the same type of the side chain chlorinated p-chloro derivatives by the chlorination under ${\gamma}$-ray irradiation, whereas ethyl ${\alpha} ,{\beta} -dichloro-{\beta}$-(o-chlorophenyl) derivatives gave o,p-dichlorophenyl derivatives. The identifications of the products were based on a radio thin layer chromatography and activation analysis of chlorine contents of product. The chlorination reaction was discussed in regards to the effect of phenyl substituents to the formation of reaction product and the procedures were described.

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Purification and Properties of $\gamma$-Glutamyl Transpeptidase from Bacillus sp. KUN-17

  • Hwang, Se-Young;Ryang, Jun-Hwan;Lim, Wang-Jin;Yoo, Ick-Dong;Kunio Oishi
    • Journal of Microbiology and Biotechnology
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    • v.6 no.4
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    • pp.238-244
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    • 1996
  • $\gamma$-Glutamyl transpeptidase ($\gamma$-GTP; EC 2.3.2.2) present in the culture filtrate of Bacillus sp. KUN-17 was purified 400-fold through a consecutive procedure including organic precipitation and column chromatography. The enzyme has an estimated molecular weight of 70, 000 and consists of hetero-subunits with molecular weights of 42, 000 and 22, 000. In vitro optimal conditions for those transfer and hydrolysis reactions appeared to be pH 7.0 at $50^{\circ}C$ and pH 8.4 at $40^{\circ}C$, respectively. The denatured enzyme recovered most of its $\gamma$-GTP activity by removing detergents such as sodium dodecyl sulfate (SDS) or urea with dialysis. The enzyme showed higher affinities against a number of amino acids as $\gamma$-glutamyl acceptors than glycylglycine in the following order: L-valine, L-methionine, L-glutamic acid or L-as-paragine, L-alanine. Also, it was shown that L-glutamine was the most suitable $\gamma$-glutamyl donor for the transfer reaction among those tested. Amino acids generally inhibited the enzyme activity for the transfer reaction, but not for the hydrolysis reaction.

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Studies on the Properties of E. coli ${\gamma}-Glutamylcysteine$ Synthetase in Relation to the Enzymatic Synthesis of Glutathione (글루타치온의 효소적 생합성에 관계되는 E.coli ${\gamma}-Glutamylcysteine$ Synthetase의 특성 연구)

  • Nam, Yong-Suk;Kwak, Joon-Hyeok;Lee, Se-Yong
    • Applied Biological Chemistry
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    • v.40 no.6
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    • pp.478-483
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    • 1997
  • ${\gamma}-Glutamylcysteine$ synthetase was purified from E. coli K-12 strain and its properties related to the in vitro synthesis of glutathione by enzymatic method were investigated. The activity of purified ${\gamma}-glutamylcysteine$ synthetase was increased with increasing concentration of L-glutamate up to 60 mM, while it was decreased by about 50% and 40% under 60 mM of L-cysteine and 45 mM of glycine, respectively. The enzyme activity was reduced not only by ADP, one of the reaction products, but also by the reduced form of glutathione. Therefore, because the reduced glutathione as well as glycine which is the substrate for glutathione synthetase inhibit the activity of ${\gamma}-glutamylcysteine$ synthetase, it is recommended to design a bioreactor system with two separate reactions for glutathione synthesis : one with ${\gamma}-glutamylcysteine$ synthetase reaction and the other glutathione synthetase reaction. In addition since ADP, resulted from these reactions, reduces the activity of ${\gamma}-glutamylcysteine$ synthetase, it is necessary to introduce an ATP regeneration system for glutathione synthesis.

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