• Korean Chemical Engineering Research
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• 제49권6호
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• pp.720-725
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• 2011

금속질산염과 염화금산을 전구체로 사용하여 다양한 금속산화물($$Al_{2}O_{3}$, ZnO, $Fe_{2}O_{3}$, $Cr_{2}O_{3}$, $MnO_{2}$, CuO, NiO, $Co_{3}O_{4}$)에 담지된 금촉매를 공침법을 이용하여 제조한 후, 일산화탄소 산화반응에서 수분첨가의 영향을 검토하였다. 이들 중 $Co_{3}O_{4}$와 ZnO에 담지된 금촉매가 일산화탄소에 대하여 높은 활성을 보여주었다. 반응가스 중에 수분이 첨가될 때 Au/$Co_{3}O_{4}$ 촉매는 활성이 약간 감소하였으나, Au/ZnO 촉매에서는 활성이 크게 증가하여 수분에 의한 일산화탄소 산화 활성은 담체의 종류에 크게 의존함을 알 수 있었다. 반응가스 중에 포함된 수분에 관계없이 반응 전과 후의 Au(5 wt%)/ZnO 촉매의 금입자 크기는 거의 변하지 않아 활성이 감소되는 이유는 금입자들의 소결에 의한 영향보다는 카보네이트와 같은 화학종에 의해 불활성화가 일어남을 알 수 있었으며, 이 화학종은 수분의 첨가에 의해 이산화탄소로 분해되어 활성이 증가한 것으로 생각된다.

• Korean Chemical Engineering Research
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• 제51권5호
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• pp.545-549
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• 2013

높은 수율로 CHMI를 제조하는 공정을 개발하기 위한 연구의 일환으로, 공정 중간체 CHMAIE를 합성하는 실험적 연구를 수행하였다. CHMAIE 제조 공정의 중간체인 CHMA 생성반응은 무수 말레인산 용액에 사이크로헥실아민을 점적 투입한 후 반응액을 2시간 동안 숙성시키는 방법으로 완료하였으며, 생성된 CHMA를 $10^{\circ}C$ 이하에서 2.5시간 동안 석출시키면 98.2%의 수율을 얻을 수 있었다. CHMA로부터 CHMAIE를 제조하는 에스테르화 반응의 최적 온도는 $68^{\circ}C$ 이었으며, 이 최적 온도에서의 평형 전화율은 98.5%였다. 에스테르화 반응이 평형에 도달하는 시간은 온도에 따라 감소하며, 최적 온도에서의 평형도달 시간은 약 3시간 정도였다. 최종 생성물 중의 톨루엔은 진공 증류를 통하여 회수할 수 있었다. 톨루엔의 회수율은 증류 온도가 증가함에 따라 증가하였고, 증류 온도 $55^{\circ}C$에서의 톨루엔 회수율은 98%였다.

• Bulletin of the Korean Chemical Society
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• 제28권1호
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• pp.53-58
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• 2007

In the dehydrogenation of ethylbenzene to styrene, CO2 could play a role as an oxidant to increase conversion of ethylbenzene and stability as well over TiO2-ZrO2 mixed oxide catalysts. TiO2-ZrO2 catalysts were prepared by co-precipitation method and were characterized by BET surface area, bulk density, X-ray diffraction, temperature programmed desorption of NH3 and CO2. These catalysts were found to be X-ray amorphous with enhanced surface areas and acid-base properties both in number and strength when compared to the respective oxides (TiO2 and CO2). These catalysts were found to be highly active (> 50% conversion), selective (> 98%) and catalytically stable (10 h of time-on-stream) at 600 oC for the dehydrogenation of ethylbenzene to styrene. However, in the nitrogen stream, both activity and stability were rather lower than those in the stream with CO2. The TiO2-ZrO2 catalysts were catalytically superior to the simple oxide catalysts such as TiO2 and ZrO2. The synergistic effect of CO2 has clearly been observed in directing the product selectivity and prolonging catalytic activity.

• 한국결정성장학회지
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• 제22권6호
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• pp.286-290
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• 2012

알루미늄 에칭 폐액으로부터 boehmite(AlOOH) 분말을 합성하였다. 폐액에서 침전되어 있는 결정상은 gibbsite ($Al(OH)_3$)였으며, 산을 이용하여 pH를 조절한 결과 pH가 7~8 영역에서 boehmite 결정상이 얻어졌다. 침전 분말에 남아 있는 Na 이온을 제거하고자 세척공정을 진행하여 boehmite 분말을 얻었다. 합성한 분말의 평균입경은 약 40 nm이었다. 또한 열처리 온도가 증가함에 따라 boehmite는 ${\gamma}-Al_2O_3$와 ${\delta}-Al_2O_3$, ${\Theta}-Al_2O_3$를 거쳐 ${\alpha}-Al_2O_3$ 결정상으로 상전이가 일어났다.

• 한국세라믹학회지
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• 제35권11호
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• pp.1171-1181
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• 1998

$SrZr_{0.95}$$Y_{0.05}$$O_{2.975}$ powder was synthesized by ultrasonic spray pyrolysis using a solution that Sr carbonate and Zr and Y nitrates were dissolved in a citric acid solution. The processes of particle formation were in-vestigated with respect to solution properties and pyrolysis temperature. With changing the solution con-centration form 0.1M to 0.01M there was a tendency that average sizes of droplets and particles were de-creased and their size distributions were narrowed. Citrate functional groups converted the droplets into gel particles which prevented an inhomogeneous precipitation of the metal ions and facilitated the diffusion of gases during thermal decomposition. As a result the powder having spherical particles without hollow par-ticles could be prepared. Low pyrolysis temperature led to amorphous particles due to incomplete pyrolysis and made the particles difficult to maintain spherical shape due to retarded gelation of the droplets. Whereas higher pyrolysis temperature produced hollow and broken particles because the droplets un-derwent rapid gelationand decomposition. The particles obtained at two pyrolysis temperature $500^{\circ}$and $1000^{\circ}C$ consisted of a perovskite phase and a very small amount of $SrCO_3$ However after calcination at $1000^{\circ}C$ the particles contained a single perovskite phase having an average particle size of 0.63${\mu}{\textrm}{m}$ and an apparent density near to the theoretical density.

• Journal of Microbiology and Biotechnology
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• 제12권2호
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• pp.189-195
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• 2002

Using Streptomyces sp. YU100 isolated from Korean soil, the fermentative production of phospholipase D was attempted along with its purification and characterization studies. When different carbon and nitrogen sources were supplemented in the culture medium, glucose and yeast extract were found to be the best. By varying the concentration of nutrients and calcium carbonate, the optimal culture medium was determined as 2.0% glucose, 1.5% yeast extract, 0.5% tryptone 0.3% calcium carbonate. During cultivation, the strain secreted most of the phospholipase D in the early stage of growth within 24 h. The phospholipase D produced in the culture broth exhibited hydrolytic activity as well as transphosphatidylation activity on lecithin (phosphatidylcholine). In particular, the culture broth showed 8.7 units/ml of hydrolytic activity when cultivated at $28^{\circ}C$ for 1.5 days. The phospholipase D was purified using 80% ammonium sulfate precipitation and DEAE-Sepharose CL-6B column chromatography, which produced a major band of 57 kDa on a 10% SDS-polyacrylamide gel with purity higher than 80%. The enzyme showed an optimal pH of 7 in hydrolytic reaction, and at pH 4 in a transphosphatidylation reaction. The enzyme activity increased until the reaction temperature was elevated to $60^{\circ}C$. The enzyme was relatively stable at high temperatures and neutral pH, but significantly unstable in the alkaline range. Among the detergents tested as emulsifiers of phospholipids, the highest enzyme activity was observed when 1.5% Triton X-100 was employed. However, no inhibitory effect by metal ions was detected. Under optimized reaction conditions, the purified enzyme not only completely decomposed PC to phosphatidic acid within 1 h, but also exhibited higher than 80% conversion rate of PC to PS by transphosphatidylation within 4 h.

• ALGAE
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• 제21권2호
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• pp.261-266
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• 2006

The innate soluble polysaccharides and phenolic compounds of marine macroalgae are serious contaminants which interfere with experimental procedures such as restriction enzyme digestion, polymerase chain reaction (PCR) and other enzymatic reactions using extracted DNA samples. The viscous polysaccharides are co-precipitated with DNA samples by isopropanol or ethanol precipitation in conventional experiment. To overcome the problem, a method for the isolation of high molecular weight DNA from Porphyra tenera is developed with the application of diatomaceous earth column. The isolated DNAs by this method were about 50-100 kb in size and could be digested well with restriction enzymes. The nuclease activity seemed to be minimal, and high reproducibility in the arbitrary primed PCR for RAPD analyses was a distinctive feature. These results suggest that this method is very efficient in isolating nucleic acid from macroalgae including Porphyra.

• 한국식품과학회지
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• 제46권3호
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• pp.364-368
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• 2014

양파가공부산물인 양파껍질을 이용하여 산업체에서 활용 가능한 추출공정으로 다양한 항산화활성 변화를 확인 하였다. 양파껍질 추출물의 총 폴리페놀 함량은 OPME-1에서 233.90 mg/g으로 가장 높게 나타났으며, DPPH법에 의한 항산화활성의 $IC_{50}$값은 OPMPE-1에서 1.15 mg/mL로 가장 높은 radical 소거활성을 나타났다. ABTS에 의한 총 항산화력은 OPM에서 432.78 mg AA eq/g으로 높은 항산화활성을 나타냈으며, 환원력은 OPMPE-1에서 1.69 $A_{700}$으로 높게 나타났고, ORAC 지수는 OPMPE-1에서 $318,509{\mu}M\;TE/mL$로 가장 높게 나타났다. 본 연구결과 실제 산업체에서 양파껍질 추출물을 제조할 때 활용 가능한 추출공정은 여러 번 반복 추출을 하는 것보다 1회 추출만 하는 공정이 항산화 활성 결과 기능성 식품소재 원료로 활용이 더 유리할 것으로 사료된다.

• Mass Spectrometry Letters
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• 제8권2호
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• pp.23-28
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• 2017

Arctigenin is the main active ingredient of Fructus Arctii, which has been reported with a variety of therapeutic activities including anti-cancer, anti-inflammation, anti-virus, and anti-obesity effects. In this study, a simple and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the determination of arctigenin in rat plasma. The assay utilized a simple protein precipitation with methanol and the mobile phase consisted of 100% methanol and water containing 0.1% formic acid (65:35 v/v). Arctigenin and the internal standard (psoralen) were monitored using a positive electrospray turbo ionspray mode with multiple reaction monitoring transitions of m/z $373.2{\rightarrow}136.9$ and m/z $187.2{\rightarrow}130.9$, respectively, and total chromatographic run time was within 5 min. The lower limit of quantification (LLOQ) of arctigenin was 5 ng/mL in the rat plasma. The intra- and inter-day accuracy of arctigenin at LLOQ and matrix-matched quality control samples ranged 97.4 - 104.8% and 97.2 - 102.0%, respectively. The intra-day precision was within 4.80% and the inter-day precision was within 5.92%. Application of the present method was demonstrated through a pharmacokinetic study after intravenous and oral administration of arctigenin in male Sprague Dawley rats.

• Preventive Nutrition and Food Science
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• 제2권2호
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• pp.174-179
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• 1997

CMCase produced by recombinant E. coli JM109 (pCEH#4) containing CMCase gene from Cellulomonas sp. YE-5 was purified to 24.3 fold and 2.6% yield by ammoniumsulfate precipitation, DEAE-cellulose column chromatography and gel filtration on Sephadex G-100. The optimum pH and temperature for CMCase activity were pH 7.0 and 5$0^{\circ}C$. The enzyme was stable between pH 5.0 and 10.0, and up to 6$0^{\circ}C$. The molecular weight of he enzyme was estimated to be approximately 40,000 daltons by SDS-PAGE. Analysis of the amino acid composition showed that the enzyme contained many glycines and acidic amino acids. The enzyme was an endo-type CMCase and the final enzyme reaction product from hydrolysis of Cm-cellulose by the enzyme was cellobiose. {TEX}$K_{M}${/TEX} value determined with CM-cellulose was 1.28mM.