• 에너지공학
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• 제20권3호
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• pp.209-215
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• 2011

본 연구에서는 저온 열교환기 효율 향상을 위하여 상온($25^{\circ}C$)과 저온($10^{\circ}C$)에서 탄소나노유체와 산화탄소나 노유체의 열전도도와 점도를 측정하였다. 탄소나노유체는 다중벽 탄소나노튜브에 계면활성제 SDS 100 wt%, 고분자 화합물 PVP 300 wt%를 각각 혼합한 뒤 증류수에 초음파 분산하여 제조하였고, 산화탄소나노유체는 산화 처리된 다중벽 탄소나노튜브를 증류수에 초음파 분산하여 제조하였다. 탄소나노유체의 열전도도는 비정상 열선법을 사용하여 측정하였으며, 점도는 회전형 디지털 점도계를 사용하여 측정하였다. 그 결과 같은 혼합비율과 온도에서 다른 탄소나노유체들 보다 산화탄소나노유체의 열전도도가 가장 높게 측정되었고, 점도는 가장 낮게 측정되었다.

• Applied Biological Chemistry
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• 제36권3호
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• pp.158-162
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• 1993

토양에서 분리한 bilirubin oxidase를 생산하는 Penicillium sp. LAM 91-89의 배양액으로부터 효소를 정제하여 여러가지 성질을 조사하였다. LAM 91-89 billirubin oxidase는 $ethanol(40{\sim}80%)$ 추출 및 2회의 Sephadex G-200 column chromatography로 약 70배 정제하였으며 회수율은 12%였다. 이 효소는 분자량이 약 53,000 dalton이었으며 $40^{\circ}C$, pH 8.5에서 최대의 활성을 보였고 pH 6에서 10까지의 넓은 범위와 $40^{\circ}C$ 이하에서 안정하였다. 또 효소의 활성이 $Mg^{2+}$에 의해서 증가하였으며 $Ag^+,\;Hg^{2+},\;Mn^{2+},\;Pb^{2+}$, p-CMB, iodoacetate 및 SDS에 의해서 저해되었다. 그리고 이 효소는 bilirubin에 대한 특이성이 컸으며 bilirubin에 대한 $K_m$값은 $6.67{\mu}M$이였다.

• 한국환경과학회지
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• 제15권5호
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• pp.485-491
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• 2006

In the aqueous solutions the dephosphorylations of isopropyl phenyl-4-nitrophenyl phosphinate(IPNPIN) mediated by hydroxide$(OH^{\theta})$ and o-iodosobenzoate$(IB^{\theta})$ ions ate relatively slow, because of hydrophobicity of the substrate, and however it appears that $OH^{\theta}$ is inherently better nucleophile than $IB^{\theta}$, which is more soft ion. On the other hand, in cetyltrimetyiammonium bromide(CTABr) solutions which contain cationic micelles, the dephosphorylations of IPNPIN mediated by $OH^{\theta}$ or $IB^{\theta}$ ate very accelerated to 120 or 100,000 times as compared with those in the aqueous solutions. The values of pseudo first order rate constants reach a maximum with increasing. Such rate maxima are typical of micellar catalysed bimolecular reactions and the rise in rate constant followed by a gradual decrese is characteristic of reactions of hydrophobic substrates. In the cationic micellar solutions of CTABr, $IB^{\theta}$ accelerates the reactions much more than that $OH^{\theta}$ does. The reason seems that $IB^{\theta}$ which is more hydrophobic and soft ion than $OH^{\theta}$ is more easily moved into the Stern layer of the CTABr micelles than $OH^{\theta}$. In the anionic micellar solutions of sodium dodecyl sulfate(SDS), the dephosrhorylations of IPNPIN ate slower than those in aqeous solutions. It means that $OH^{\theta}$ or $IB^{\theta}$ cannot easily move and approach to the Stern layer of the micelle in which almost all the hydrophobic substrate are located and which has a negative circumstance.

• Asian Pacific Journal of Cancer Prevention
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• 제14권7호
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• pp.4135-4139
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• 2013

Inflammation is potential risk factor of various human malignancies. Inflammatory bowel syndromes such as ulcerative colitis are well known as risk factors for colon cancer. Here, we examined enhancing effects of dextran sulfate sodium (DSS)-associated inflammation on X-irradiation induced colonic tumorigenesis in Min and wild-type (WT) mice. Animals were X-irradiated at 1.5 Gy at 5 weeks of age (at 0 experimental week) and 2% DSS in drinking water was administered at 5 or 11 experimental weeks. Mice were sacrificed at 16 weeks and incidence and multiplicity of colonic tumors were assessed. Incidence of colonic tumors in Min mouse was increased from 33.3% to 100% (p<0.05) with X-irradiation alone, whereas no tumors were developed in WT mice. In DSS-treated Min mice, X-irradiation increased the number of colonic tumors. Total number of colonic tumors was increased 1.57 times to $30.7{\pm}3.83$ tumors/mouse with X-irradiation+DSS at 5 weeks comapared to $19.6{\pm}2.9$ in corresponding DSS alone group (p<0.05). When the duration of inflammation was compared, longer period of DSS effect promoted more colonic tumorigenesis. Collectively, we conclude that X-irradiation and DSS-induced inflammation act synergistically for colonic tumorigenesis.

• 한국환경과학회지
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• 제12권2호
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• pp.217-225
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• 2003

Samples of size-fractionated PM10 (airborne particulate matter with aerodynamic diameter less than $10\mu\textrm{m}$) were collected at an urban site in Jeju city from May to September 2002. The mass concentration and chemical composition of the samples were measured. The data sets were then applied to the CMB receptor model to estimate the source contribution of PM10 in Jeju area. The average PM10 mass concentration was 28.80$\mu\textrm{g}/m^3$ ($24.6~33.49\mu\textrm{g}/m^3$), and the FP (fine particle with aerodynamic diameter less than $2.l\mu\textrm{m}$ fraction in PM10 was approximately 8% higher than the CP (coarse particle with aerodynamic diameter greater than $2.l\mu\textrm{m}$ and less than $10\mu\textrm{m}$ fraction in PM10. The CP composition was obviously different from the FP composition, that is, the most abundant water soluble species was nitrate ion in the FP, but sulfate ion in the CP. Also sulfur was the most dominant element in the FP, however, sodium was that in the CP. From CMB receptor model results, it was found that road dust was the largest contributor to the CP mass concentration (45% of the CP) and ammonium nitrate, domestic boiler, and marine aerosol were major sources to the CP mass. However, the secondary aerosol was the most significant contributor to the FP mass concentration (45% of the FP). In this study, it was suggested that the contributions of soil dust and gasoline vehicle became very low due to collinearity with road dust and diesel vehicle, respectively.

• BMB Reports
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• 제35권3호
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• pp.291-296
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• 2002

Thanatin, a 21-residue peptide, is an inducible insect peptide with a broad range of activity against bacteria and fungi. It has a C-terminal disulfide loop, like the frog skin secretion antimicrobial peptides of the brevinin family. In this study, we tried to find the effect of a number of amino acids between the disulfide bond. Thanatin showed stronger antibacterial activity to Gram negative bacteria than other mutants, except Th1; whereas, the mutant peptides with deletion had higher activity to Gram positive bacteria than thanatin. An increase in the number of amino acid(s) using the alanine residue decreased the antibacterial activity in all of the bacteria. Th1 with deletion of threonine at position 15 ($Thr^{15}$) showed similar antibacterial activity against Gram-negative bacteria, but had higher activity against the Gram positive bacteria. In order to study the structure-function relationship, we measured liposome disruption by the peptides and CD spectra of the peptides. Th1 also showed the highest liposome leaking activity and α-helical propensity in the sodium dodecyl sulfate solution, compared with other peptides. Liposome disruption activity was closely correlated with the anti-Gram positive bacterial activity. All of the peptides showed no hemolytic activity. Th1 was considered to be useful as an antimicrobial peptide with broad spectrum without toxicity.

• Biomolecules & Therapeutics
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• 제5권2호
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• pp.165-173
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• 1997

This study was conducted to investigate the effect of DA-9601, an extract of Artemisiae Herba, which is known to possess mucoprotective action either by free radical scavenging effect or increase of mucus secretion, against animal models of inflammatory bowel disease (IBD) induced by trinirobenzene sulfonic acid (TNBS) or other noxious agents. Experimental colitis was induced by intracolonic administration of TNBS in 50% ethanol, or 1 ml of 7% acetic acid solution (AA), by subcutaneous injection of indomethacin (INDO) in rats, or by supplementing drinking water with 5% dextran sodium sulfate (DSS) in albino mice. DA-9601 was treated orally for 4 to 7 days. Animals were euthanized 1 day after the last treatment for morphological and biochemical analysises. All the noxious agents including TNBS, AA, INDO and DSS elicited severe colitis. The animals treated with DA-9601 showed a consistent, dose-related reduction in the severity of colitis, grossly and histologically. The reduction was significant (p<0.05) after administration of DA-9601 at dose range of 10 mg/kg or above. In TNBS-induced colitis, the rats receiving DA-9601 showed significantly decreased mucosal myeloperoxidase (MPO) and thiobarbituric acid-reactive substances (TBA-RS), when compared to control and mesalazine groups. Mucosal proinflammatory cytokine levels were also decreased after DA-9601 treatment. In conclusion, DA-9601 ameliorated macroscopic and histologic scores in experimental colitis either through decreasing oxidative stress or by attenuating cytokines involved in inflammation. DA-9601 could be a promising drug for the therapy of IBD.

• 한국산학기술학회논문지
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• 제11권9호
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• pp.3341-3346
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• 2010

이 연구는 세치제 내 함유되어 있는 SLS의 함유여부에 따라 구강 내 타액과 세균수의 변화정도를 비교분석하여 향후 보다 양질의 세치제 개발을 위한 기초자료를 제공하고자 하였다. SLS의 함유량을 2.2%와 0.0%의 세치제를 제조하여 각각 30명으로 구성된 두 집단의 실험대상자에게 4주간 사용하게 하고 실험 전 후의 타액과 구강 내 세균 수의 변화 차이를 보았다. 연구결과 SLS의 배합여부는 타액, 세균수의 변화에 현저한 차이를 보이지 않았다. 또한 SLS 배합여부는 타액량과 구강 내 세균수의 관련성이 없는 결과를 보였다. 하지만 실험대상자들이 사용한 세치제에 대한 만족도 조사에서는 SLS가 함유되지 않은 그룹 보다 SLS가 함유된 그룹에서 만족도가 현저하게 높은 것으로 나타났다. 만일 SLS가 선호감 때문에 이용되고 있다면 SLS의 적정 함유량에 대한 구체적 개선방안을 모색하여 할 것이다.

• Biomolecules & Therapeutics
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• 제15권2호
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• pp.123-126
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• 2007

A sensitive, simple and highly selective liquid chromatography method of determination for extraction of pseudoephedrine hydrochloride from Allegra D tablet was developed. The chief benefit of the present method is the minimal sample preparation, as the procedure is only filtering through pore syringe filter. Two drugs (pseudoephedrine hydrochloride, fexofenadine) were separated on a C$_{18}$ column and analyzed by high performance liquid chromatography (HPLC). The method had a chromatographic run time of 8.0 min. 1 ml of pseudoephedrine hydrochloride solution (1 mg/ml) was filtered through 0.22 um pore syringe filter. 50 ul of filtering solution was injected to HPLC pump and we knew the retention time (1.85 min) of separating of pseudoephedrine hydrochloride using UV detector at 280 nm. We used C$_{18}$ column (4.6 mm${\times}$250 mm), mobile phase solution (<0.05 mol/L NaH$_2$PO$_4$, 2 ml/L H$_3$PO$_4$>/CH$_3$CN / sodium dodesyl sulfate = 60 ml / 40 ml / 1 g). We separated psedoephedrine hydrochloride at run time of 1.85 min from Allegra D tablet solution (1 mg/ml) filtered through 0.22 um pore syringe filter using UV detector at 280 nm. Flow rate was set at 1.0 ml/min and the column temperature was set at 40$^{\circ}C$. Psedoephedrine hydrochloride solution (1 mg/ml) separated from Allegra D tablet was filtered through 0.22 um pore syringe filter and injected 50 ul. We confirmed the peak of psedoephedrine hydrochloride at same retention time and the separating solution was freeze-dried. In conclusion, A simple isocratic reverse-phase HPLC method has been developed that provides excellent separation of pseudoephedrine from Allegra D tablet.

• 한국미생물·생명공학회지
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• 제29권4호
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• pp.221-226
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• 2001

S. thermocyaneoviolaceus 가 생산하는 xylanases를 황산암모늄에 의한 염석 및 투석에 의해 조제한 효소를 이용하여 자일로오리고당을 생산하기 위한 최적 반응조건을 설정하였다. 자알로올리고당 생산을 위한 기질로는 oat spelt xyaln 보다 birchwood xylan을 사용하는 것이 더 좋았다. 반응온도의 영향을 조사한 결과 효소의 열 안정성과 자일로올리고당의 생선량 등을 고려할 때 $60^{\circ}C$에서 반응하는 것이 가장 좋았다 효소의 농도 pH의 영향및 반응시간의 영향을 조사한 결과 10 unit/ml xylanases를 첨가하여 pH 6.0에서 12 시간 반응시켰을 때 가장 많은 양의 자일로올리고당을 생산할 수 있었다. 이러한 최적 반응 조건에서 10% birchwood xylan 으로 부터 생산할 수 있는 자일로올리고당의 조성는 X2, X3, X4, X5 및 X6가 각각 20.1, 8.9 , 4.5, 16.2 및 9.1 g/I 이었으며 이때 생산되는 총 자일로올리고당 (X2~X6)은 58.8 g/I 이었다.