• 한국식품영양학회지
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• 제6권4호
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• pp.322-328
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• 1993

A study of general characteristics of acetone extracted pigment from the cell mass of Rhodospirillum rusrum DSM 467 was carried out for the development of natural food colorant. Through visible absorption scanning, it showed seven absorption peaks at 355, 410, 529, 624, 680 and 747nm, and it was shown to be yellow color. In acidic and neutral conditions, the color was yellow, while in the alkaline condition it was greenish yellow. This pigment was stable at pH range between 3.0~10.0, and below 4$0^{\circ}C$. In the presence of light and oxygen, the stability of pigment rapidly degraded and it became unstable in the presence of metal ions such as Cu2+, Al3+ and Fe3+. Through TLC analysis, it was shown to be composed of seven color fractions.

• Current Research on Agriculture and Life Sciences
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• 제22권
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• pp.49-56
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• 2004

Cellulolytic enzymes were prepared from alkaline resistant microorganisms which were newly screened from calcic soil. Characteristics of enzymes and enzymatic deinking efficiency of wastepaper were investigated. The results were summarized as fellows: 1. The recovery rate of crude enzyme was 93.7% in Bio-B and 57.4% in Bio-F. 2. The protein content in crude enzymes was lowest and the thermal stability of crude enzymes was highest in Bio-F. 3. The brightness gain of Bio-F deinked pulp was best in ONP and Bio-B deinked pulp was best in MOW. 4. The reject yield was increased with enzymatic deinking flotation process. 5. The residual ink area of paper was increased with enzymatic deinking and large size of ink particles were remained in paper.

• Journal of Applied Biological Chemistry
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• 제61권4호
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• pp.351-355
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• 2018

Treatment towards wound healing, a complex and dynamic process, has been given a great deal of efforts in the last few decades. Focus has been imposed on developing wound dressings that meet the requirements for proper wound healing. In this study, hydrogel made from blends of poly (vinyl alcohol) and ${\beta}$-1,6-branched-${\beta}$-1,3-glucan (beta-glucan) were synthesized by modified solvent casting method for wound dressing application. Optimization of hydrogel composition and analysis of wound dressing parameters such as stability and fluid uptake capacity (in the presence of water, saline and different pH solutions) has been studied. The result indicated that the PVA/beta-glucan hydrogel hold its structural integrity even at alkaline pH (pH~9) and upholds fluids four times of its original weight. Thus, the developed hydrogel is expected to be a promising candidate as wound dressing.

• 한국표면공학회지
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• 제55권2호
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• pp.38-50
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• 2022

As a low-cost and high-efficiency electrocatalysts with high performance and stability become a key challenge in the development of the practical use of water electrolysis, there is an intense interest in transition-metal oxalate-based materials. Transition-metal oxalate-based catalysts with excellent electrochemical performances have been widely applied in water electrolysis due to its low-cost and ease of synthesis. This review provides a useful summary on the development of transition-metal oxalate as potential catalysts for water electrolysis with a focus on the structural and compositional alteration, role of oxalate anion, and enhanced electrochemical performances.

• 공업화학
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• 제31권1호
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• pp.61-66
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• 2020

본 연구에서는 압착·코팅방식 촉매 제조 공정에 첨가제로 사용되는 콜로이드 실리카의 특성이 제조된 촉매의 성능 및 열적 안정성에 미치는 영향을 연구하였다. 이를 위해 4종의 콜로이드 실리카를 대상으로 실리카 형상 및 크기, 비표면적 및 기공특성, 성분 등을 분석하였으며 해당 콜로이드 실리카를 적용하여 제조한 V₂O₅/TiO₂ 촉매의 특성 평가 및 NOx 전환율에 대한 연구를 수행하였다. 콜로이드 실리카를 이용하여 제조한 촉매의 특성은 적용한 콜로이드 실리카의 특성에 따라 달라지며, 특히 콜로이드 실리카 내 피독물질 함량은 촉매 성능에 직접적인 영향인자인 것으로 분석되었다. 또한 콜로이드 실리카 내 실리카 함량이 높을수록 촉매의 열안정성과 성능이 향상되는 것으로 나타났다.

• 한국환경보건학회지
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• 제31권6호
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• pp.498-503
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• 2005

Stability of soybean isoflavone isomers according to extraction conditions such as temperature, pH, and extracting solvents was investigated. Heating induced three chemical reactions to occur for malony1 derivatives of isoflavones, namely decarboxylation of malony1 groups into acety1 derivatives, deesterification of malony1 residues, and hydrolysis of $\beta$-glycosidic bonds. Among the twelve isoflavone isomers, change in concentrations of acety1glycosides were most pronounced: Acety1 derivatives were present only in trace amounts in unheated hypocotyls, but the content increased dramatically during heating. As for the glycosides, concentrations of daidzin and glycitin increased due to heat treatment, though that of genistin remained almost unchanged. Heat decomposition rates and the patterns differed among the three malony1 derivatives. After 120 min at $80^{circ}C$, the relative concentrations of daidzin, glycitin and genistin were increased from $9.2\%$, $12.4\%$ and $3.3\%$ to $19.3\%$, $21.9\%$ and $6.2\%$, respectively. When crude isoflavones were solubilized in glycine buffer (pH 10.0) and incubated at $80^{circ}C$, deesterification occurred faster than at pH 7.0. When the pH of isoflavone solution was increased, the malony1glycosides were hydrolyzed to their respective glycosides at increased rate. Both acetyl and aglycone forms were unchanged and only de-esterification reactions occurred. At the acidic pH, malonylglycosides were much stable both at 60 and $80^{circ}C$. However at pH 10, $80^{circ}C$ and 1 hr, $75-80\%$ of malonylglycosides were transformed to their deesterified glycosides. When isoflavones were extracted with $60\%$ aqueous ethanol at $60^{circ}C$, isoflavone isomers were stable and the deesterification reactions did not occur in these conditions. However, at $80^{circ}C$ deesterification of malonyiglycosides occurred significantly with $15-20\%$ of malonylglycosides being hydrolyzed into their respective glycosides. This experiment showed that malonylglycosides undergo decomposition when heated or exposed to alkaline conditions. Also, aqueous ethanol was preferred to aqueous methanol as solubilizing media for obtaining extract with minimum degradation of malonylglycosides.

• 생명과학회지
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• 제20권11호
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• pp.1656-1661
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• 2010

난황단백질 가수분해를 위한 알칼리성 단백질분해효소를 5가지 담체 Duolite A568, Celite R640, Dowex-1, Dowex 50W 그리고 Silica gel R60 에 고정화하였다. Duolite A568의 경우에 24.7%의 최대 고정화 효율을 나타내었다. 자유 효소와 고정화 효소에 대한 최적의 pH는 각각 8과 9였고, 최적의 pH는 고정화에 의해 염기성으로 1만큼 증가하였다. 그러나 최적 온도는 자유 효소와 고정화 효소 모두 $50^{\circ}C$로 같았다. 고정화 효소가 자유 효소에 비해 높은 열 안정성을 보였다. 재사용 회분식 공정에서 10 cycle 동안 효소활성은 초기 활성의 86%를 유지하였다. 연속 공정을 위한 충진층 반응기에서 여러 유속에 대한 장기 조업에서 효소 활성의 안정성 평가하였는데 낮은 유속일수록 높은 활성을 유지하였다. 연속 조업에서 casein과 난황 단백질을 사용하여 원료에 대한 고정화 효소의 활성에 대한 영향을 조사하였다. 96시간 연속 조업에서 casein의 경우는 초기 활성의 83%를 유지하였고 난황 단백질의 경우는 초기 활성의 61%를 유지하였다.

• 한국식품영양과학회지
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• 제30권6호
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• pp.1147-1151
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• 2001

치자열매에서 geniposide를 추출하여 glycine과 반응시켜 얻은 치자 청색소를 식품에 활용하기 위하여 pH, 온도 및 첨가물에 대한 안정성과 음료 모델의 관능적 특성을 조사하였다. 치자 청색소는 산성에서 불안정하였으며 중성이나 알칼리성 조건에서는 매우 안정하였다. 상온에서 청색소는 매우 안정하여 약 93일의 반감기를 나타내었고, 온도가 증가할수록 분해속도가 증가하여 9$0^{\circ}C$에서는 약 2일의 반감기를 나타내었다. 혼합 이온용액($Na^{+}$, $K^{+}$, $Mg^{2+}$, $Ca^{2+}$) 0.01 M을 첨가한 경우 45일 저장 후 대조군에 비해 색소 잔존율이 높았다. 당의 종류는 색소의 안정성에 큰 영향을 미치지 않는 것으로 나타났고, 아미노산을 첨가할 경우에는 색소를 약간 안정화시켰으나, 비타민 C를 첨가할 경우 청색소의 안정성을 크게 떨어뜨리는 것으로 나타났다. 치자 청색소를 첨가한 모델음료의 관능평가 결과 대조군에 비해 당류나 무기이온, 아미노산을 첨가한 시료에 대해 높은 선호도를 나타내었다.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 1999년도 추계학술발표논문집
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• pp.180-186
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• 1999

Alkaline peroxide bleaching of (chemi) mechanical pulp is a very complicated system where various process factors affect the bleaching performance and pulp properties. Traditional on-factor-at a time method is ineffective and costly in finding the optimal bleaching conditions. In this study statistical experimental methods which include three steps. I. e. screening, response surface modeling and optimization, were used to find the conditions for maximal brightness development during one stage alkaline peroxide bleaching of TMP which had an initial brightness of 54.5% Elerpho. The TMP was pretreated with EDTA(0.5% on O. D. pulp. consistency, $30^{\circ}C$ for 60 minutes) and bleached in a 2L Mark V Quantum Reactor at 750rpm, 7.5% of bleaching consistency and with 0.05% magnesium sulfate addition. The ranges of other factors studied were 1~5% hydrogen peroxide on O. D plup, 1~4% sodium hydroxide on O. D pulp and 1~4% sodium silicate on O. D pulp, reaction temperature 50~$90^{\circ}C$ and reaction time 40~180minutes. A models with good predictability was established and the maximal brightness after one stage bleaching was found to be 70% Elerpho at $50^{\circ}C$, 50 minutes 5% hydrogen peroxide on O. D. pulp 3.2~3.4% sodium hydroxide on O. D. pulp 3.2~3.4% sodium hydroxide on O. D pulp and 4% silicate on O. D pulp. However further studies on other pulp properties such as strength and brightness stability shall be carried out in order to find out the optimal bleaching conditions.

• E2M - 전기 전자와 첨단 소재
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• 제9권6호
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• pp.605-615
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• 1996

In this paper, the effect of alkaline oxide addition such as Li$_{2}$O and Na$_{2}$O on the microstructure and humidity sensitivity of V$_{2}$O$_{5}$(2 mol%)-doped TiO$_{2}$(98 mol%) was investigated as a function of amount (0, 1, 2, 5, 10 mol%) of Li$_{2}$O and Na$_{2}$O additives. The pores in the alkaline free sample were distributed mostly in the range between 0.16 and 1.0.mu.m in diameter and its porosity was 23.29%. Li$_{2}$O caused grain overgrowth and reduced the porosity with a narrow distribution of the pore size, leading to poor humidity sensitivity. Na$_{2}$O helped to enlarge the distribution of the pore size through the formation of small soluble phases. The pore sizes of the sample containing Na$_{2}$O 2mol% were distributed mostly in the range between 1.0 and 2.5.mu.m in diameter and its porosity and intrusion volume of mercury were 31.13 % and 0.1155 mL/g respectively, which consequently improved the humidity sensing characteristics such as the sensitivity and temperature-stability. Especially, the addition of 2mol% of Na$_{2}$O improved the humidity-sensing characteristics such as sensitivity and linearity in the whole range between 30 and 90 %RH (Percentage Relative Humidity)y)