• Korean Chemical Engineering Research
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• 제43권5호
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• pp.621-626
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• 2005

Amberlyst-15 고체 산 촉매를 사용하여 올레산을 메탄올과 반응시켜 바이오 디젤의 성분이 되는 지방산 메틸 에스테르로 전환시켰다. 본 연구에서는 시료의 산가를 측정하고 전환율을 구함으로써 반응 온도, 메탄올 대 올레산의 몰 비 및 촉매의 양이 반응에 미치는 영향을 살펴보았다. 실험 범위 내에서 반응 온도가 $20^{\circ}C$ 상승할 때에 반응 속도는 약 2배씩 증가하였다. 그리고 메탄올 대 올레산의 몰 비가 증가 될 때는 최종 전환율은 증가하였지만, 반응에는 뚜렷한 차이가 없었다. 촉매 역시 반응에 중요한 변수로써, Amberlyst-15의 양을 2배로 증가시켰을 때, 반응속도는 1.2-1.3배 빨라졌다. 실험 데이터를 정량적으로 해석하기 위해 동역학식 연구를 하였으며 모사 균일 혼합물 모델(pseudo-homogeneous model)을 이용한 2차 반응 속도식을 전개하였다.

• 공업화학
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• 제29권1호
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• pp.62-66
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• 2018

Styrenated phenol alkoxylate (SP-A)는 일반적으로 균일계 염기 촉매 하에서 styrenated phenol (SP)과 ethylene oxide (EO)로부터 제조되어진다. 그러나, 취급이 용이하지 않은 EO를 사용하려면 고압반응장치를 이용한 반응공정 제어가 필요하다. 또한, 균일계 염기 촉매를 사용하면 반응종결 후에 잔존하는 염기를 제거하기 위한 중화공정이 필요하고, 촉매와 생성물의 분리가 어렵다는 문제점이 있다. 따라서, 본 연구에서는 균일계 염기 촉매를 사용하지 않고 불균일계염기 촉매를 사용하여 SP와 ethylene carbonate (EC)의 반응으로부터 제조된 SP-A에 대하여 보고하고자 한다. SP-A의 제조에 사용된 불균일계 염기 촉매는 KOH를 $La_2O_3$에 담지시킨 후, 소성하여 얻었다. 또한, EO 대신 EC를 사용함으로써 고압반응이 아닌 상압반응 조건에서 SP-A제조가 가능하였다. 합성된 SP-A의 평균 분자량 크기는 반응조건에 따라서 매우 다양하게 나타났다. $KOH/La_2O_3$촉매 하에서 제조된 SP-A의 평균 분자량 크기는 반응온도, 촉매의 첨가량 및 EC의 첨가량을 조절함으로써 임의로 조절이 가능하였다.

• 한국식품영양과학회지
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• 제40권5호
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• pp.738-746
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• 2011

Microbial transglutaminase(MTGase)를 이용하여 쌀 가수분해물과 초미세 생대두 분말을 혼합하여 전두부를 제조한 후 조직감, 동적점탄성, 단백질 결합패턴 및 미세구조를 평가하였다. 40%(w/v) 쌀 용액을 Termamyl 효소처리($85^{\circ}C$, 20분) 하였을 때 점조도 값 및 환원당 함량이 각각 $1.27\;Pa{\cdot}s^n$, 9.0%로 나타났다. MWSP 18~22% 농도에서 MTGase 효소로 응고시킨 전두부의 물성을 측정한 결과 MWSP 22% 첨가구에서 전형적인 두부의 조직감을 얻었으며, 쌀 가수분해물 7.5% 첨가구의 경우 경도 639.6 dyne/$cm^2$, 탄성 0.96으로 나타났다. MTGase 5%의 첨가 조건에서 MWSP 18~22% 농도에 따라 동적점탄성을 측정한 결과 MWSP 22% 첨가 경우 반응 6분 이내 G'(5.1 Pa) 및 G''(9.0 Pa)값으로 높게 나타났다. MWSP 22% 첨가구에서 시간에 따른 SDS-PAGE 상에서 대부분의 콩 단백질은 30분 이내에 중합되어 고분자중합체를 형성하였으며, 쌀 가수분해물이 첨가된 경우에도 대부분의 콩 단백질들이 중합되는 유사한 경향을 보였다. 쌀이 첨가된 전두부의 미세구조는 균일한 입자로 채워진 네트워크 구조를 보였으나 냉장저장 2일 후에는 쌀을 첨가하지 않은 대조구에 비해 더욱 거칠어진 표면을 확인할 수 있었다.

• 한국결정성장학회지
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• 제15권1호
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• pp.39-44
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• 2005

적점토 60 wt%, 석탄회 20 wt%, 석분오니 20 wt%를 혼합하여 제작한 sheet 형태의 소지에 인덴트(indent)를 주고 건조방법, 파쇄방법, 성형방법을 변화시켜 1～5 mm 골재의 파쇄율을 알아보았다. 소지를 건조할 때 실내와 실외에서의 자연건조, 건조기건조, 마이크로웨이브(microwave)건조, 급속건조로 분류하여 비교실험 하였고, 파쇄방법은 볼밀 Ⅰ 파쇄, 볼밀 Ⅱ 파쇄, 낙하파쇄, 기계식 파쇄(롤러밀사용)법으로 변화를 주었다. 성형방법은 인덴트의 간격과 깊이를 변화시키면서 동시에 소지의 두께를 변화시켜 실험하였다. 건조방법에 의한 비교실험 결과는 210초까지 건조시킨 마이크로웨이브건조가 약 42%로. 파쇄방법에서는 볼밀 Ⅱ 파쇄법이 약 65 %로 가장 높은 파쇄율을 보였고, 성형방법에서는 인덴트의 깊이가 깊어질수록(3mm의 소지에서만), 소지의 두께가 증가할수록 크기가 Ф=5 mm보다 큰 골재의 수율은 감소했고 Ф=5 mm 이하인 골재의 수율은 증가했다. 각각의 실험 후 파쇄 된 1～5mm 골재의 aspect ratio를 비교해본 결과 3mm 두께의 소지를 급속건조법에 의해 건조하고 볼밀 Ⅱ법을 이용해 파쇄 한 경우 가장 균일한 골재의 모양으로 파쇄 되었음을 알 수 있었다.

• 자원환경지질
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• 제44권1호
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• pp.71-82
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• 2011

본 연구는 국내에서 산사태 발생빈도가 높은 선캠브라아기 편마암 풍화토와 백악기 화강암 풍화토를 대상으로 하여 불포화 풍화토별 강우강도 및 흙의 단위중량에 따른 강우침투속도 관계를 파악하기 위하여 불포화 풍화토 칼럼시험을 하였다. 본 연구에서는 일정시간 간격으로 체적함수비, 간극수압 등을 TDR센서와 간극수압계를 통해 측정하였다. 현장 건조단위중량을 기준으로 느슨한 조건, 현장조건, 조밀한 조건으로 선정하고, 강우강도를 20 mm/h와 50 mm/h로 선정하여 시험을 수행하였다. 강우강도 20 mm/h 조건에서 각 단위중량 조건별 편마암 풍화토와 화강암 풍화토의 평균 강우침투속도는 각각 $2.854{\times}10^{-3}$ cm/s ~ $1.297{\times}10^{-3}$ cm/s와 $2.734{\times}10^{-3}$ cm/s ~ $1.707{\times}10^{-3}$ cm/s였으며, 강우강도 50 mm/h 조건에서는 각 풍화토별로 $4.509{\times}10^{-3}$ cm/s ~ $2.016{\times}10^{-3}$ cm/s와 $4.265{\times}10^{-3}$ cm/s ~ $3.764{\times}10^{-3}$ cm/s로 나타났다. 시험결과 강우강도가 높고 흙의 단위중량이 낮을수록 평균 강우침투속도는 증가하였으며, 느슨한 조건을 제외한 모든 조건에서 화강암 풍화토의 강우침투속도가 편마암 풍화토의 강우침투속도보다 빠르게 나타났다. 이는 화강암 풍화토가 편마암 풍화토에 비해서 입도가 비교적 균질하며, 단위중량이 낮고 공극율이 큰 것이 그 원인으로 판단된다.

• Asian-Australasian Journal of Animal Sciences
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• 제11권4호
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• pp.368-374
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• 1998

The study was conducted on six multiparous Murrah buffaloes which were earlier artificially induced into lactation. During the experimental period of 15 days, buffaloes were managed in a loose housing system. All the buffaloes were administered a single injection of bromocryptine (@ $100{\mu}g/kg$ body weight) subcutaneously in the neck region at 08:30 A.M., 50 days postpartum (early lactation). Blood samples were collected from four buffaloes for a period of 5 days before the administration of bromocryptine i.e. on days -5, -4, -3, -2, -1, on day of treatment (day 0) and thereafter daily for a period of 9 days i.e 1, 2, 3, 4, 5, 6, 7, 8 and 9 to determine the hormones and blood metabolites. Homogeneous milk samples from all the buffaloes were collected at morning and evening milkings on days coinciding with the days of blood sampling for analysis of milk constituents. Administration of bromocryptine resulted in a significant inhibition of plasma prolactin within 24 hrs of treatment, but the response in all the buffaloes was not uniform. The effect of bromocryptine on plasma prolactin hormone lasted for 1-4 days but Cortisol concentration were not altered. Administration of bromocryptine neither affected blood glucose nor plasma non-esterified fatty acids concentration. Irrespective of level of milk production from different buffaloes, there was no effect of bromocryptine on milk yield which indicated that prolactin is not required for milk secretion during early lactation in buffaloes. Milk constituents like fat, protein and lactose were not affected by bromocryptine may be due to no effect of bromocryptine of milk yield.

• BMB Reports
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• 제32권2호
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• pp.133-139
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• 1999

Thioltransferase, also known as glutaredoxin, was previously purified and characterized from Chinese cabbage (Brassica campestris ssp. napus var. pekinensis). However, in the process of gel filtration on Sephadex G-75, there were two activity peaks. In this study, a second thioltransferase (TTase CC-2) in the minor peak of the Sephadex G-75 elution profile was further purified using affinity chromatography on an S-hexylglutathione-agarose column by eluting with buffer solution containing 2.5 mM S-hexylglutathione. It showed a single band on SDS-PAGE indicating that TTase CC-2 is electrophoretically homogeneous. The molecular weight of TTase CC-2 was estimated to be about 22,000 daltons, and its isoelectric point was determined to be 6.73. Its size appears to be atypical and much larger than that of the first thioltransferase (TTase CC-1) from Chinese cabbage, and it can utilize 2-hydroxyethyl disulfide, S-sulfocysteine, and insulin as substrates. S-sulfocysteine was found to be a superior substrate for TTase CC-2. TTase CC-2 also displayed the reducing activity for non-disulfides such as dehydroascorbic acid. Its optimum pH was 8.5, which was consistent with that of TTase CC-1. TTase CC-2 activity was greatly activated by L-cysteine and reduced glutathione, and was found to be less heat-stable compared with TTase CC-1. Molecular and physiological differences between TTase CC-1 and TTase CC-2 remain to be elucidated. Chinese cabbage is the first plant which is known to contain two kinds of thioltransferases.

• 한국축산식품학회지
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• 제38권5호
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• pp.866-877
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• 2018

Cheese emulsion is an intermediate product for the production of cheese powder and needs to be stable, homogeneous and pumpable characteristics to convey to the spray drier. This study was conducted to evaluate the effects of fat reduction and emulsifying salt (ES) amount in cheese emulsion systems on the physicochemical characteristics. Reduced-fat (RF) and full-fat (FF) white-brined cheese emulsions were produced with different dry matters (DM; 15%-25% excluding ES) and ES concentrations (0%-3% based on cheese weight). Stable cheese emulsion was obtained at lower DM in RF cheese emulsion than that of FF cheese emulsion. Reduction in the amount of ES resulted in instability of both emulsions. Apparent viscosity with pseudoplastic flow behavior significantly increased with the decrease of fat content in stable cheese emulsions. Microstructure of emulsions appeared to be related to the fat content, stability and degree of emulsification. Reduction of fat content caused to get less lightness and more greenness in color, whereas yellowness was significantly decreased by increase in the amount of ES. In conclusion, fat reduction resulted in higher viscosities of cheese emulsion due to inducing the increment of protein, and the addition amount of ES considered as very important factor to produce stable cheese emulsion without protein precipitation or cream separation. Therefore, for preparation of RF cheese emulsion using a variety of white-brined cheese, lower amounts of DM would be suggested in this study to obtain homogenous droplets in the atomizing process of spray drying.

• Journal of Microbiology and Biotechnology
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• 제9권4호
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• pp.450-456
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• 1999

A high molecular-weight water-soluble fraction(PO) obtained by the ethanol precipitation of 0.1 N NaOH extracts of the mushroom Pleurotus ostreatus showed 82% anti-complementary activity for complement consumption hemolysis. The PO consisted of 42% carbohydrate (w/w), 50% protein (w/w), and 3% uronic acid (w/w). Fifty-eight percent of the anti-complementary activity decreased by periodate oxidation and 22% by protease digestion, suggesting that the sugar and protein moieties are essential for this activity. Two polysaccharide fractions, PO-IIIa-1 and PO-IIIa-2, with anti-complementary activity were isolated from the PO using DEAE-Sepharose FF followed by Sephadex G-75 and Sepharose CL-6B gel permeation chromatographies. The PO-IIIa-2 was found by HPLC to be nearly homogeneous, with the molecular mass of 531 kDa, and showed 96% $ITCH_{50}$ (inhibition against the total complement hemolysis of deionized water as the control) at a concentration of 1 mg/ml. This fraction contained galactose, mannose, fucose, and glucose with molar ratios of 1.75:1:0.65 and 0.59, respectively. The majority of galactose and mannose units in the PO-IIIa-2 were composed of TGalp1 ->, ->6Galp1->, ->2,6Galp1->, and ->Manp1->. The PO-IIIa-1 (molecular mass of 2000 kDa), exhibiting higher activity than the PO-IIIa-2, was further purified into two fractions, unbound proteoglycan (PO-IIIa-1A) and bound glucomannan (PO-IIIa-lB), by affinity chromatography using ConA-Sepharose CL-4B. The anti-complementary activity of each affinity purified fraction decreased as compared to that of the native PO-IIIa-1 fraction, indicating that the formation of complex between both polysaccharide fractions was necessary for full anti-complementary activity.

• International Journal of Industrial Entomology and Biomaterials
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• 제6권1호
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• pp.33-44
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• 2003

The arylphorin was purified from the pupal haemolymph of the Chinese oak silkmoth, Antheraea pernyi, and characterized physiologically and biochemically, The protein was purified by a simple preparative polyacrylamide gel electrophoresis (PAGE) and subsequent diffusive elution. The preparation was shown to be homogeneous by 7.5% native-PAGE. The native molecular weight of arylphorin was 450 kDa with a 80 kDa single subunit, suggesting hexamer, The protein contained high amounts (18.3%) of aromatic amino acids, phenylalanine (9.7%) and tyrosine (8.6%). Therefore, the protein was identified as a kind of a storage protein referred to as an arylphorin. The protein was stained by Schiff's reagent, suggesting a glycoprotein. The protein contained 4.9% (w/w) sugar and mannose and N-acetylglucosamine were major components. Also, degradation of the protein was begun by heat treatment at 90 for 20 minutes. These results showed that the A. pernyi arylphorin in the study is hexamer associated with the six subunits consisting of a 80kDa single subunit, and is different from that of Kajiura et al. (1998) in the subunit composition.