• Bulletin of the Korean Chemical Society
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• 제28권12호
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• pp.2324-2328
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• 2007

Organic fluorine chemistry produces many useful products. This paper elucidates the reaction of ethyl-4,4- difluoro-2-iodo-5-oxo-5-phenylpentanoate (2) with primary amines in a one-pot scheme. The reaction produced a series of β-fluoropyrrole derivatives at ambient temperatures. In this reaction, the less bulky the primary amine the higher was the resultant yield. When (2) and aqueous methylamine (40%) were allowed to react below 0 oC, 5-(ethoxycarboxyl)-1-methyl-3,3-difluoro-2-hydroxy-2-phenylpyrrolidine, an intermediate molecule for 2-ethyl-4-flouro-1-methyl-5-phenylpyrrole-2-carboxylate (5), was isolated first. Then, (5) reacted with hydroperchloric acid and acetic anhydride to form 5-(ethoxycarboxyl)-1-methyl-3,3-difluoro-2- phenylpyrrolinium perchlorate (6), which was converted to 2-ethyl-4-flouro-1-methyl-5-phenylpyrrole-2- carboxylate gradually in the presence of a base. Our experiments demonstrate that the formation of 2-ethyl-4- flouro-1-methyl-5-phenylpyrrole-2-carboxylate occurs via both one-pot schemes and stepwise pathways, depending on the reaction conditions. The isolation and characterization of the isolated intermediate (6) suggest an anionic pathway for this reaction.

• Bulletin of the Korean Chemical Society
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• 제20권11호
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• pp.1303-1308
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• 1999

Conducting poly(3,4-ethylenedioxythiophene) (PEDT) films with metalloporphyrins incorporated as the counter ions were prepared by electropolymerization of the monomer in the presence of metal-tetra(sulfonatophenyl) porphyrin anions. Cathodic reduction of oxygen on the resulting conducting polymer films was studied. The overpotential for O2 reduction on electrodes with cobalt-porphyrin complex was significantly smaller in acidic solutions than on gold. In basic solutions, the overpotential at low current densities was close to those on platinum and gold. Polymer electrode with Co-complex yielded higher limiting currents than with Fe-complex, although the Co-complex polymer electrode was a poorer electrocatalyst for O2 reduction in the activation range of potential than the Fe counterpart. From the rotating ring-disk electrode experiments, oxygen reduction was shown to proceed through either a 4-electron pathway or a 2-electron pathway. In contrast to the polypyr-role-based electrodes, the PEDT-based metalloporphyrin electrodes were stable with wider potential windows, including the oxygen reduction potential. Their electrocatalytic properties were maintained at temperatures up to 80℃ in KOH solutions.

• 대한화학회지
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• 제20권4호
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• pp.295-298
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• 1976

Organothioenamine phosphonate와 styrene oxide 와의 반응에서 얻어진 생성물의 구조를 규명한 결과 그것이 cyclopropane 유도체임을 알았다. 이것은 반응이 styrene oxide에 대한 thioenamine phosphonate의 친핵공격에 의해서 생긴 산소 음이온이 다시 인 원자를 공격함으로서 중간체로 betain이 형성 된다음 이어서 약한 P-C 결합이 끊어지면서 생성물로 이끌어져 감을 가리켜 주고있다. 또한 생성물의 광학활성을 조사한 결과는 우회전성 이어서 이 반응은 중간체에서 생긴 benzyl carbon의 입체적 효과를 받으며 어디까지나 안정한 경로를 거쳐서 이끌어져 감을 알 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제21권8호
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• pp.823-827
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• 2000

Gas-Phase reactions of methyl and ethyl nitrites with anionic nucleophiles of SH-, F- and OH- are investigated theoretically at the MP2/6-311+G* level. The SN2 processes are all highly exothermic and proceed with a typ-icaI double-weIl reaction coordinate profile. The elimination reactions of methyl nitrite with SH- and F- are double-well energy surface processes,with stabilizedproduct complexes of NO-...H2S and NO-...HF, pro-ceeding by an E1 cb-like E2 mechanism. The $\beta-elimination$ of ethyl nitrite is an E2 type process. The $\alpha-elimi-nation$ reactions of methyl and ethyl nitrites with OH- have triple-well energy profiles of Elcb pathway with an $\alpha-carbanion$ intermediate which is stabilized bythe vicinal $nc\alpha-{\sigma}*o-N$ charge transfer interactions. CompIex-ation ofmethyl carbanion with HF seems to provide a stable intermediate within a triple-well energy profile of El cb channel in the reaction of F- with methyl nitrite.

• Asian-Australasian Journal of Animal Sciences
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• 제24권3호
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• pp.369-378
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• 2011

The effect of a homolactic inoculant containing a blend of Lactobacillus plantarum, Pediococcus acidilactici and Enterococcus faecium or, the anionic surfactant, sodium dodecyl sulphate (SDS), alone or in combination on fermentation characteristics, aerobic stability and in situ DM, OM and NDF degradability of barley silage was investigated. Barley (Hordeum vulgare, L.) was harvested (45% DM), chopped and treated with water at 24 ml/kg forage (Control), inoculant at $1.09{\times}10^5$ cfu/g forage (I), SDS at 0.125% (wt/wt) of forage (S) or with the inoculant ($1.09{\times}10^5$ cfu/g) plus SDS (0.125% wt/wt; I+S). The treated forages were ensiled in triplicate mini silos and opened for chemical and microbiological analyses on d 1, 2, 3, 7, 14, 42 and 77. Silage samples from d 77 were opened and aerobically exposed for 7 d. The in situ rumen degradability characteristics of silage DM, OM and NDF were also determined. The terminal concentration of NDF in S and I+S was lower (p<0.001) than in other treatments. Lactate concentration was higher (p<0.001) and the rate and extent of pH decline were greater (p<0.001) in I and I+S than S and Control silages. A homolactic pathway of fermentation in I and I+S was evidenced by reduced (p<0.001) water-soluble carbohydrates concentration, higher lactate (p<0.01), lower acetate (p<0.01) and lower pH values (p<0.001) than in S and Control silages. All silages remained stable over 7 d of exposure to air as indicated by lower temperatures and moulds, and by non-detectable yeast populations. The treated silages had lower DM and OM degradability than in the Control but NDF degradation characteristics of I+S were improved compared to other treatments. It is concluded that the inoculant alone improved the fermentation characteristics whereas the combination of the inoculant with SDS improved both fermentation and NDF degradability of barley silage.

• 대한화학회지
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• 제27권3호
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• pp.213-217
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• 1983

태양에너지의 한 저장방법으로 녹색식물의 광합성을 모방한 계, 마이크로 에멀젼(microemulsion)을 고안하였으며, 이때 광에 의해서 유발된 전자가 계면을 통하는 능력을 측정하였다. 광증감제로 류테니늄비피리딘 착물$[Ru(bipy)_3]^{2+}$을 사용, 전자공여체 EDTA와 함께 물층에, 전자수용체 $HV^{2+}$(Hexadecyl violagan)이 계면에 각각 존재할 때 광에 의한 전자전이에 따르는 $HV^+$ 형성수득률은 0.12이였다. 또 계면에 $BNA^+$(Benzyl nicotinamide)를 넣고 유층에 아조(azo) 화합물을 넣었을 때는 azobenzene이 환원되었는데, 이때 양자수득률이 줄었다. (${\Phi}$ = 0.0016) 양이온 마이크로 에멀젼과 음이온 마이크로에멀젼의 광유발 전자전이 능력을 비교하였다. 광증감제로 유기염료인 로즈벤갈(Rose bengal)을 시험하였는데, 류테니늄착물보다 낮지 않았지만 광유발 전자가 계면에 전이되는 것을 알았다.

• 대한핵의학회지
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• 제20권1호
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• pp.33-37
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• 1986

It is well known that $^{99m}Tc-sulfur$ colloid or phytate hepatic scintigraphy is highly sensitive but not specific. Both $^{99m}Tc-DISIDA$ and bilirubin have been shown to share the same anionic transport pathway in the liver. Hepatocellular carcinoma(HCC) retains the ability to produce bile but has marked limitation to excreting it resulting in accumulation of bile within the tumor cells. Based upon such a fact, $^{99m}Tc-DISIDA$ hepatobiliary scintigraphy is used for the diagnosis of HCC. The present communication deals with our experience of DISIDA scintigraphic exploration of 9 cases of HCC in a retrospective way. We have made an observation on intensity of positive radio nuclide accumulation in the cold area of HCC as it is demonstrated by phytate scintigraphy. In addition we have semi quantitatively analyzed time-activity pattern and the following results were obtained. (1) All of 9 cases showed an increased uptake of $^{99m}Tc-DISIDA$ in delayed scintigrams. Of these 5 cases showed accumulation less than, 3 equal to, 1 more than the surrounding liver tissue. (2) The mean of the first appearing time of $^{99m}Tc-DISIDA$ activity in tumoral region was 2 hours and 20 minutes. (3) DISIDA scintigraphy provides us with positive informations of diagnostic value.

• Nuclear Engineering and Technology
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• 제26권2호
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• pp.285-293
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• 1994

압축 벤토나이트에서 핵종이동은 확산에 의해 지배된다. 국산 벤토나이트에 대한 음이온핵종의 확산 특성 규명을 위해서 요오드이온을 대상으로 관통확산실험을 수행하였다. 대상매질은 동해안 지역의 벤토나이트를 사용하였으며, 실험용액은 합성 모의지하수에 I-125를 첨가하여 사용하였다. 압축 벤토나이트의 충전밀도는 1.2, 1.4, 1.7Mg/㎥등 세가지로 하였다. 요오드이온의 겉보기확산계수와 유효확산계수는 충전밀도가 증가함에 따라 감소하였고, 이들 확산계수의 값은 각자 3.80-7.12$\times$$10^{-11}$ $m^2$/s와 1.25-7.97$\times$$10^{-12}$ $m^2$/s의 범위에 있었다. 실험결과, 겉보기확산계수는 벤토나이트의 공극구조에 의존하였으며, 유효확산계수는 공극구조는 물론 핵종확산이동에 이용된 유효공극율에 의해 좌우되었다. 본 연구에서 얻어진 결과는 처분장안전성평가의 기초자료로 활용될 것이다.

• Journal of Animal Science and Technology
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• 제59권7호
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• pp.16.1-16.6
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• 2017

Background: This study was performed to investigate the impact of exogenous ghrelin on the pancreatic ${\alpha}$-amylase outputs and responses of pancreatic proteins to ghrelin that may relate to pancreatic exocrine. Methods: Sprague-Dawley male rats (9 weeks old, $300{\pm}10g$) were injected with ghrelin via intraperitoneal (i.p.) infusion at dosage of 0, 0.1, 1.0 and $10.0{\mu}g/kg$ body weight (BW), respectively. The plasma ghrelin and cholecystokinin (CCK) level were determined using enzyme immunoassay kit; the mRNA expression of ghrelin receptor ($GHSR-1{\alpha}$) and growth hormone (GH) receptor were assessed by reverse transcription PCR; the expressions of pancreatic ${\alpha}$-amylase activity, extracellular-signal-regulated kinases (ERK), phosphorylated extracellular-signal-regulated kinases (pERK) and c-Jun N-terminal kinase (JNK) were evaluated by western blotting; moreover the responses of pancreatic proteins to ghrelin were analyzed using the two-dimensional gel electrophoresis system. Results: The exogenous ghrelin (1.0 and $10.0{\mu}g/kg\;BW$) elevated the level of plasma ghrelin (p < 0.05), and suppressed the expression of pancreatic ${\alpha}$-amylase at a dose of $10.0{\mu}g/kg\;BW$ (p < 0.05). No difference in the level of plasma CCK was observed, even though rats were exposed to any dose of exogenous ghrelin. In addition, a combination of western blot and proteomic analysis revealed exogenous ghrelin ($10.0{\mu}g/kg\;BW$) induced increasing the JNK and ERK expressions (p < 0.05) and four proteins such as Destrin, Anionic trypsin-1, Trypsinogen, and especially eukaryotic translation initiation factor 3 in rat pancreas. Conclusions: Taken together, exogenous ghrelin by i.p. infusion plays a role in the pancreatic exocrine secretion via mitogen-activated protein kinase signaling pathway.