• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2008년도 추계학술대회B
• /
• pp.2688-2691
• /
• 2008

This study addresses a microfluidic method to uniformly form diacetylene (DA) liposomes and control their size. DA liposomes are biochemical sensor materials with a unique property such that when they are polymerized to polydiacetylene (PDA) they exhibit non-fluorescent blue to fluorescent red phase transition upon chemical or thermal stress. The liposome size and distribution are important because they significantly affect the phase transition. So far, DA Liposomes, have been prepared by mixing of bulk phases leading to heterogeneous, polydisperse distribution in size. Therefore, additional post-processes are required such as sonication or membrane extrusion to obtain an appropriate size of liposomes. Here, we report a novel strategy using a microfluidic chip and hydrodynamic focusing to form DA liposomes and control their size. Preliminary results obtained by scanning electron microscope (SEM) and dynamic light scattering (DLS) show that the microfluidic strategy generates more monodispersed liposomes than a bulk method.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2008년도 추계학술대회B
• /
• pp.2696-2699
• /
• 2008

Microfluidic chips have been frequently utilized to perform biochemical analysis, like cell culture, because they reduce the consumptions of analytes and reagents and automate multi-step analysis processes. It is often critical to monitor temperature in a microchannel for the analyses in order to control a reaction condition of bio or chemical molecules. We propose a novel method to monitor temperature of a microchannel flow by using polydiacetylene (PDA), a conjugated polymer, that has a unique property to transform its color from visible blue to fluorescent red by thermal stress. We inject PDA sensor droplets generated by hydrodynamic instability into a microchannel with a microheater incorporated on the channel bottom. Also, we change the channel temperature by providing the different electric power to the microheater. The results show that the florescence intensity of PDA sensor droplets linearly increases in response to the flow temperature increase within a certain range.

• 한국식품과학회지
• /
• 제53권6호
• /
• pp.815-818
• /
• 2021

The objective of this study was to develop a differential medium with improved selectivity for the isolation of Bacillus cereus. Mannitol egg yolk polymyxin medium supplemented with D-galactose allowed the differentiation of diarrheal- and emetic-type B. cereus through pH monitoring. The pH of the medium decreased significantly when incubating the emetic-type B. cereus, whereas the pH change was not significant when incubating the diarrheal-type. The addition of pH indicators, such as methyl red and phenol red, to the medium allowed visual differentiation between diarrheal- and emetic-type B. cereus. A solid agar medium was also developed by optimizing the concentrations of medium components such as monosaccharides, agar, egg yolk enrichment, pH indicators, and antibiotics. This study indicates the possibility of applying selective media for the differentiation of diarrheal- and emetic-type B. cereus.

• Fisheries and Aquatic Sciences
• /
• 제4권4호
• /
• pp.163-170
• /
• 2001

The effect of perilla oil added in diet on the biochemical properties of cultured sweet smelt, Plecoglossus altivelis, was investigated. The cultured fish were fed two different diets for 8 weeks; a control diet was a commercial diet, which was low in the content of docosa­hexaenoic acid (DHA, 22: 6n-3) and eicosapentaenoic acid (EPA, 20: 5n-3) less than approximately $2\%$ (CO group) and an experimental diet (PO group) was added perilla oil as a lipid source in the diet of the CO group. The PO group was superior in growth rate and feed efficiency compared with CO group. This trend showed markedly in female of both groups. The fatty acid composition in the muscle of PO group was closely related with those of the diet, while those of CO group were not. For plasma components, total cholesterol (CHOU of PO group was higher than that of CO group. Thiobarbituric acid-reactive substances (TBARS), hydroxyl (OH) radical levels and superoxide dismutase (SOD) activity of plasma were higher in PO group than CO group. The intensity of watermelon-like or cucumber-like aroma was much stronger in PO group with higher level of TBARS and OH radical in plasma compared CO group. Survival rate was also high in PO group with high levels of phagocytic rate, CHOL and SOD activity. These results suggest that perilla oil might be usefulness as a lipid source of the cultured sweet smelt diet, in which result in high quality of the cultured fish.

• Applied Biological Chemistry
• /
• 제25권4호
• /
• pp.224-231
• /
• 1982

liposome에 결합되어 있는 ${\alpha}-Tocopherol$의 형광을 이용하여 liposome의 상전이온도를 측정할 수 있었다. 이는 ${\alpha}-Tocopherol$의 vitamin E로서의 중요성 이외에 형광성 프로브로서의 새로운 가치의 발견이다. 형광성 프로브로서 그 응용의 확대를 위한 필수적인 기초자료의 수집을 위해, 분자분광학적성질을 조사하였다. 용액중의 ${\alpha}-Tocopherol$은 monomer와 dimer의 두가지 형태로 존재하며, 단파장흡수대$(291{\sim}294nm)$의 monomer는 형광성인데 반하여 dimer는 298nm 부근을 흡수하는 비형광성이고 분자간수소결합에 의하여 형성되었음이 밝혀졌다. liposome에 결합된 ${\alpha}-Tocopherol$은 각종 유기용매 중에서의 ${\alpha}-Tocopherol$과는 판이한 형광성질을 갖고 있었고 chromanolate이온형태의 화학종으로부터 생긴 것으로 해석되었다.

• Asian Pacific Journal of Cancer Prevention
• /
• 제14권5호
• /
• pp.3191-3196
• /
• 2013

Leaf extracts of Cassia alata L (akapulko), traditionally used for treatment of a variety of diseases, were evaluated for their potential antitumor properties in vitro. MTT assays were used to examine the cytotoxic effects of crude extracts on five human cancer cell lines, namely MCF-7, derived from a breast carcinoma, SK-BR-3, another breast carcinoma, T24 a bladder carcinoma, Col 2, a colorectal carcinoma, and A549, a nonsmall cell lung adenocarcinoma. Hexane extracts showed remarkable cytotoxicity against MCF-7, T24, and Col 2 in a dose-dependent manner. This observation was confirmed by morphological investigation using light microscopy. Further bioassay-directed fractionation of the cytotoxic extract led to the isolation of a TLC-pure isolate labeled as f6l. Isolate f6l was further evaluated using MTT assay and morphological and biochemical investigations, which likewise showed selectivity to MCF-7, T24, and Col 2 cells with $IC_{50}$ values of 16, 17, and 17 ${\mu}g/ml$, respectively. Isolate f6l, however, showed no cytotoxicity towards the non-cancer Chinese hamster ovarian cell line (CHO-AA8). Cytochemical investigation using DAPI staining and biochemical investigation using terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL)-a method used to detect DNA fragmentation-together with caspase assay, demonstrated apoptotic cell death. Spectral characterization of isolate f6l revealed that it contained polyunsaturated fatty acid esters. Considering the cytotoxicity profile and its mode of action, f6l might represent a new promising compound with potential for development as an anticancer drug with low or no toxicity to non-cancer cells used in this study.

• KSBB Journal
• /
• 제31권3호
• /
• pp.171-177
• /
• 2016

The effects of medicinal mushroom (Sparassis crispa) powder supplementation on the rheological property of dough and the quality of bread were investigated. Naturally dried S. crispa powders (NDSCP) and freeze-dried ones (FDSCP) were prepared. Farinograph profiles of dough showed that mushroom powder addition at levels higher than 1% led to reduced dough stability suggested by decreased development time and increased weakness. The incorporation of S. crispa powders was significantly (p<0.05) lower compared to other mushrooms which might be attributed to its high content of beta-glucan. FDSCP was chosen over NDSCP because of its fragrant flavor which could be ascribed to the preservation of volatile polyphenol components. The quality of FDSCP bread was evaluated with respect to specific volume, texture, color, and organoleptic qualities. The specific volume of bread with S. crispa powder decreased compared to the control, while textural properties, such as hardness, chewiness, and gumminess, were enhanced. Sensory evaluation showed that 0.3% FDSCP incorporation presented the highest bread quality. With its daily consumption, S. crispa supplemented bread can provide consumers with multiple health benefits.

• 환경영향평가
• /
• 제25권2호
• /
• pp.124-140
• /
• 2016

본 연구는 한국노동패널(Korea Labor and Income Panel Study, KLIPS) 제1차~제15차년도 자료와 환경부에서 제공하는 수질자료를 이용하여, 개인의 전반적인 생활만족도(life satisfaction)가 수질오염으로 대표되는 환경오염에 의해 어떻게 영향을 받는가를 실증적으로 분석한 것이다. 서수적 순서를 가진 종속변수의 특성과 패널자료의 이질성을 감안하여 패널 확률효과 순서형 프로빗(panel random-effects ordered probit) 모형으로 추정하였다. 수질오염도를 반영하는 지표로는 생물화학적 산소요구량(biochemical oxygen demand, BOD), 총인(total phosphorus, TP) 농도를 사용하였다. 또한 기존의 연구에서와 같이 개인의 경제적 특성, 사회 인구학적 특성을 동시에 고려하였다. 분석 결과 BOD, TP 모두 개인의 생활만족도에 부정적인 영향을 미치는 것으로 나타났다. 그 외 다른 변수들은 선행연구에서 나타난 결과와 유사하다. 자신의 소득 증가, 연령, 기혼, 자가주택 보유, 건강, 여성, 높은 교육수준은 생활만족도에 긍정적인 영향을 미치며, 타인의 소득 증가, 실업자, 도시거주, 자영업자인 경우는 부정적인 영향을 미치는 것으로 나타났다.

• 한국응용과학기술학회지
• /
• 제33권4호
• /
• pp.771-776
• /
• 2016

내열, 코팅 및 접착특성이 우수한 아크릴계 공중합체를 설계, 제조하였다. 공중합체용 모노머로 methyl methacrylate(MMA), isobornyl methacrylate(IBMA) 그리고 2-hydroxyethyl methacrylate(HEMA)를 사용하여 괴상 중합 및 유화 중합으로 반응하여 > 95%이상 고수율로 중합체를 제조하였다. $^1H$-NMR로 화학구조를 확인하였고 DSC, DMA, TGA분석으로 내열성을 확인한 결과 유리전이온도가 $123^{\circ}C$이상 $140^{\circ}C$까지 높게 나타났다. 또한, IBMA성분이 증가함에 따라 저장 탄성율, 열분해온도 모두 증가하였다. 인장강도는 IBMA의 함량이 전체 모노머 조성물중 10%에서 30%로 증가함에 따라 괴상 및 유화 중합체 모두에서 22에서 30 MPa로 강도가 증가하였으며 IBMA의 소수성 특성으로 접촉각은 70도에서 88도까지 증가함을 확인하였다.

• 접착 및 계면
• /
• 제9권1호
• /
• pp.22-27
• /
• 2008

아크릴 점착제의 점착력을 목표 수준으로 향상시키기 위해 실험계획법을 이용하여, 2-ethyl hexyl acrylate (2-EHA), ethyl acrylate (EA), metha acrylic acid (MAA), acryl amide (AAm)를 라디칼 용액 중합하여 점착력을 측정하였다. 실험계획법은 반응표면분석법의 하나인 혼합물 설계를 이용하여 특수 3차 모형으로 분석하였으며, 그 적용은 상용프로그램인 MINITAB을 사용하였다. 수립된 실험계획에 의해 실험하고 분석한 결과, 목표하는 점착력을 얻기 위한 단량체 조성은 2-EHA (0.8861), EA (0.0639), MAA (0.03), AAm (0.02)로 나타났으며, 그 회귀분석 식은 다음과 같았다. $$y=54.8816x_1+80.7067x_2-44.4700x_3-99.0288x_1x_2+60.7706x_1x_3-441.030x_2x_3+974.341x_1x_2x_3$$.