• Biotechnology and Bioprocess Engineering:BBE
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• 제7권2호
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• pp.76-84
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• 2002

On-line conversion estimation of enzymatic esterification reactions in solvent-free media was investigated. In principle, conversion to ester can be determined from the amount of water produced by the reaction, because water is formed as a by-product in a stoichiometric manner. In this study, we estimated the water production rate only from some measurements of relative humidity and water balances without using any analytical methods. In order to test the performance of the on-line conversion estimation, the lipase-catalyzed esterification of n-capric acid and n-decal alcohol in solvent-free media was performed whilst controlling water activity at various values. The reaction conversions estimated on-line were similar to those determined by offline gas chromatographic analysis. However, when the water activity was controlled at higher values, discrepancies between the estimated conversion values and the measured values became significant. The deviation was found to be due to the inaccurate measurement of the water content in the reaction medium during the initial stages of the reaction. Using a digital filter, we were able to improve the accuracy of the on-line conversion estimation method considerably. Despite the simplicity of this method, the on-line estimated conversions were in good agreement with the off-line measured values.

• 한국세라믹학회지
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• 제46권2호
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• pp.170-174
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• 2009

$BaTiO_3$ powder was synthesized by the solid-state reaction of fine $BaTiO_3$ and $TiO_2$ raw materials. Fine grinding media of 50 and 300 microns were used for obtaining fine particulate mixture of $BaTiO_3$ and $TiO_2$ with high homogeneity. Effect of the size of grinding media on the synthesis mechanism of $BaTiO_3$ was discussed on the basis of the particulate morphology and thermogravimetry data for the mixture powders. By using the finer grinding media, $BaTiO_3$ was formed at the lower temperature and the particle size with the relatively narrower distribution could be obtained. $BaTiO_3$ powder with the average size of 100 nm was synthesized by the solid reaction in vacuum atmosphere.

• 대한화학회지
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• 제17권4호
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• pp.262-268
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• 1973

p-Phenylenediamine을 과량의 진한 염산 및 과염소산을 매질로하여 거의 완전히 tetrazo화 하였다. Tetrazonium염의 두 diazo기를 할로겐으로 치환하여 생긴 dihalobenzene의 수량으로 반응의 정도를 알아 보았다. 이 반응의 성패는 tetrazonium염의 안정도에 의하여 죄우되었으며, 그 안정도는 매질의 종류, 산도(농도) 및 그양과 밀접한 관계가 있음을 알았다. 즉 산매질의 농도가 너무 묽으면 tetrazonium염은 불안정하여 완전히 분해되었으며, 매질의 농도가 너무 진하면 tetrazonium염은 안정한 반면에 tetrazo화 반응이 방해되었다. 이 상반되는 두 경향을 조화시키기 위해서는 tetrazonium염이 안정하게 존재할 수 있는 가장 낮은 농도의 산을 매질로 써야함을 알 수 있었다. p-Phenylenediamine의 tetrazo화에서는 약$40{\sim}45$%의 산매질이 적당하였다. $H^+$이온이 부촉매로 작용하는 것으로 보아 diazo화 반응이 아민의 염의 상태에서 일어나는 것이아니고 유리상태의 아민과 nitroso group 사이에서 일어난다는 설이 타당함을 알 수 있었다. Tetrazo화 반응을 diazo화 반응의 kinetics 및 mechanism과 관련시켜서 설명하였다.

• KSBB Journal
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• 제9권3호
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• pp.306-311
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• 1994

유기용매상에서 Bacillus licheniformis에서 생산되는 protease를 이용하여 라세믹 ${\alpha}$-methylbenzy lamine의 광학분함을 행하였다. 이 반응은 아설 제 공자로 활성 에스대르를 샤용하여 라서l믹 아민을 광 학선택적으로 아마드로 변환시킨다. 이 반응의 반응 속도와 광학선택성을 증가시켜주기 위해 효소를 완 충액에 녹여 pH를 맞춘 후에 동결건조시키거나, 동결건조시 염이나 lyoprotectants를 첨가시키는 방 법, 적당한 유기용매의 선정, 에스테르 구조의 디자 인 등의 방법을 사용하였다. 그 결과. 30배의 초기 반응속도의 증가 및 12배의 광학선택성이 증가하는 결과를 보였다.

• 약학회지
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• 제44권1호
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• pp.36-40
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• 2000

The photodegradation of pefloxacin, photolabile fluoroquinolone antibacterial agent, was studied. In the presence of $N_2$, photodegradation of pefloxacin was suppressed. The singlet oxygen and free radical generated in the reaction media proceeded photochemical reaction. The photodegradation of peflxacin was sensitized by benzophenone, a triplet state sensitizer.

• Allergy, Asthma & Respiratory Disease
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• 제6권6호
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• pp.315-321
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• 2018

Purpose: Radiocontrast media are widely used in medical imaging to improve diagnostic accuracy. However, studies on the adverse reactions of radiocontrast media in children are limited. We aimed to describe the characteristics of adverse reactions to radiocontrast media among children who had a computed tomography scan or magnetic resonance imaging in a tertiary university hospital. Methods: We retrospectively collected data on adverse reactions to radiocontrast media by the reporting system of a tertiary university hospital. We selected data from children under the age of 19 from July 2011 to December 2017 and analyzed their characteristics. We focused mainly on the characteristics of the index case which is defined by the first adverse event of each subject. Results: During the period, a total of 88,050 radiocontrast media-enhanced imaging studies were performed and 184 cases of adverse reactions were reported. A total of 71 were identified as index cases. Forty-nine (69.0%) were male and the mean age was $12.7{\pm}3.2$ years. The incidence of radiocontrast media-related adverse reactions was 0.09% and severe reactions were 0.002%. The most common clinical feature was skin manifestations (54.9%), followed by gastrointestinal symptoms (40.8%) and neuropsychiatric symptoms (7.4%). Conclusion: Adverse reactions to radiocontrast media rarely occur in children and the incidence of severe reactions is low. Most reactions are mild and are related to the skin and gastrointestinal system. This report would provide good evidence for establishing a management strategy in children scheduled for imaging studies using radiocontrast media.

• 한방안이비인후피부과학회지
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• 제17권2호
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• pp.1-11
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• 2004

Objective: Chronic otitis media is an inflammation and infection of the middle ear which is persistent. Chronic otitis media occurs when the eustachian tube becomes blocked repeatedly, multiple infections, ear trauma, or swelling of the adenoids. A chronic ear may be the result of an acute ear infection that does not clear completely, or the result of recurrent ear infections. A chronic ear infection may be more destructive than an acute ear infection because its effects are prolonged, and it may cause permanent damage to the ear. Methods : Experimental animals made use of 4-5 weeks age(weight 20-25g) ICR(male)mouse. In the breeding farm, the lighting time was controlled from 7:00 am until 7:00 pm, the temperature was controlled within $22{\pm}0.5{\circ}$ and water and food were not limited. The extracts which were extracted from Hwangginaetak-san devided low dose group( 1.0g/kg-HN) and high dose group(3.0g/kg-HN), they were intragastrically administered to the mouse of sample A and sample B prior to LPS I.P injection. Compared with inflammation induced group which were induced by LPS, we measured the WBC count, IL-6 level in plasma and TNF-${\alpha}$ level in plasma. Results: 1. Hwangginaetak-san decreased WBC count in inflammatory reaction induced by LPS 2. Hwangginaetak-san decreased IL-6 level in inflammatory reaction induced by LPS. 3. Hwangginaetak-san didn't decreased TNF-${\alpha}$ level in inflammatory reaction induced by LPS Conclusion: According to above results, Hwangginaetak-san was improved its suppression effect to the inflammatory reaction through WBC count and IL-6 level. So Hwangginaetak-san is considered to be used for treatment of chronic otitis media by controlling the WBC count and IL-6 level in plasma.

• 생명과학회지
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• 제13권2호
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• pp.143-149
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• 2003

This experiment was undertaken to investigate proper conditions for protoplast isolation and regeneration from the mycelia of Lyophyllum ulmnrium. Protoplast isolation and regeneration are influenced by a variety of factors such as enzyme, osmotic stabilizer, reaction time and age of mycelia. A combination of Novozyme 234 (10mg/ml) and cellulase Onozuka R-10 (10 mg/ml) with 0.6 M $MgSO_4$ was most effective for isolation of the protoplasts. The optimum reaction time of the mycelia with the lytic enzymes was 3.5~4 hours at $28^{\circ}C$ in shaking condition at 120 strokes per min. High yield of the protoplasts were obtained from its 4~5 days old mycelia on complete agar media. Its protoplasts were regenerated to normal hyphae. Regeneration media with 0.6 M sucrose were proper for regeneration of the protoplasts. Their regeneration frequency on complete agar media was 2.3~2.7%.

• Bulletin of the Korean Chemical Society
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• 제13권4호
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• pp.395-398
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• 1992

Rate of solvolysis of dansyl chloride in aqueous binary mixtures of acetone, methanol and ethanol are reported. Kinetic solvent isotope effects in methanol and product selectivities in alcohol-water mixtures are also reported. Kinetic data are interpreted with the Grunwald-Winstein and Kivinen equations. The value of $k_{CH3OH}/k_{CH3OD}=1.76$ suggests that a general have catalyzed and/or an $S_AN$ pathway is operative in methanol, a less polar solvent. Rate-rate profiles for solvolysis of dansyl chloride in the aqueous binary media indicate a change in reaction channel from $S_AN$ (in less polar media) to $S_N2$ (in more polar media) mechanism.

• 한국인쇄학회지
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• 제7권1호
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• pp.65-72
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• 1989

Modified phenolics can have a retarding effect on the gelation of wood oil. Modified phenolic resins can be used in media for paint, varnishes, primers, overprinting varnishes, litho, letterpress and rotogravure inks. Varnishes based on rosin phenolic are faster drying, have better durability, are harder and glosser, and have greater resistance to water than ones based on ester gums. These physical properties is concerned with molecular weight distribution of rosin modified phenol resin. This paper was studied about molecular weight distribution of rosin phenolics which were prepared between $130~250^{\circ}C$. The results were as follows: 1) Average molecular weights inereased with increasing reaction temperature. 2) $M_w/M_n$ were from 3.43 to 46.44 with increasing reaction temperature and so the molecular weight distributions were changed from random distribution to broad distribution. 3) The relation ship between intrinsic viscosity and weight average molecular weight was follows: $[{\;}{\;}]={\;}1{\times}{\;}10^{-6}M_w,{\;}M_w=M_w$ 4) Esterification reaction between the acid group of rosin and polyol was started about $230^{\circ}C$$.