• Fisheries and Aquatic Sciences
• /
• 제12권2호
• /
• pp.86-89
• /
• 2009

2,3,6-Tribromo-4,5-dihydroxybenzyl methyl ether (TDB) from the methanolic extract of the red alga Symphyocladia latiuscula exhibits major antioxidant activity. In this study, the activity of TDB against oxidative damage in deoxyribose and DNA was investigated in vitro for potential applications in preventing mutagenesis caused by DNA damage. TDB inhibited the oxidation of deoxyribose at concentrations of up to $1{\mu}g$/mL in the presence of $Fe^{+3}$-EDTA/$H_2O_2$. Furthermore, TDB showed no pro oxidant activity as determined by absence of the reduction of bleomycin-$Fe^{+3}$ to bleomycin-$Fe^{+2}$, which leads to DNA damage. Based on these results, TDB demonstrated considerable antioxidant activity without prooxidant properties.

• 한국지능시스템학회논문지
• /
• 제14권2호
• /
• pp.190-194
• /
• 2004

본 논문에서는 비선형 생화학적인 공정의 모델링을 위해 퍼지시스템이 응용된 것을 보인다. SBR 반응조에서 질소제거를 위한 수처리 공정이 제시되었으며, 이 공정의 ORP값을 모델링하고 동정하기 위해 서로 다른 후반부 다항식을 가진 퍼지시스템이 소개되었다. 퍼지모델링 결과를 비교하고 분석하며 또한 제안된 방법에 의해 비선형 공정이 합리적이고 효율적으로 모델링 될 수 있음을 본 논문에서 보인다.

• 대한기계학회논문집B
• /
• 제31권10호
• /
• pp.855-859
• /
• 2007

Hydrogen as an energy carrier in fuel cell offers perhaps the largest potential benefits of reduced emissions of pollutants and greenhouse gases. The generation of high-purity hydrogen from hydrocarbon fuels is essential for efficient operation of fuel cell. Reduction of carbon monoxide to an acceptable level of 10ppm involves high temperature and low temperature water gas shift (WGS), followed by selective oxidation of residual carbon monoxide. The WGS reactor was designed and tested in this study to produce hydrogen-rich gas with CO to less than 5000 ppm. In the water gas shift operation, gas emerges from the reformer is taken through a high temperature shift (HTS) catalyst to reduce the CO concentration to about $2{\sim}4%$ followed to about 5000 ppm via a low temperature shift (LTS) catalyst.

• 한국물환경학회지
• /
• 제29권6호
• /
• pp.777-781
• /
• 2013

Ion-exchange technology is one of the best for removing nitrate from drinking water. However, problems related to the disposal of spent brine from regeneration of exhausted resins must be overcome so that ion exchange can be applied more widely and economically, especially in small communities. In this background, a combined bio-regeneration and ion-exchange system was operated in order to prove that nitrate-laden resins could be bio-regenerated through direct contact with denitrifying bacteria. A nitrate-selective A520E resin was successfully regenerated by denitrifying bacteria. The bio-regeneration efficiency of nitrate-laden resins increased with the amount of flow passed through the ion-exchange column. When the fully exhausted resin was bio-regenerated for 5 days at the flowrate of 30 BV/hr and MLSS concentration of $125{\pm}25mg/L$, 97.5% of ion-exchange capacity was recovered. Measurement of nitrate concentrations in the column effluents also revealed that less than 5% of nitrate was eluted from the resin during 5 days of bio-regeneration. This result indicates that the main mechanism of bio-regeneration is the direct reduction of nitrate by denitrifying bacteria on the resin.

• 한국환경과학회지
• /
• 제21권10호
• /
• pp.1187-1193
• /
• 2012

The aim of this research is to enhance the bottom environment of Geoje fish farm that has been severely contaminated. Treatment of microbial agent and/or calcium oxide significantly changed that environment: in ignition loss, either treatment (25% or 21%) showed better than mixed treatment (13.2%). In COD, the oxygen releasing agent or mixed treatment reduced the index by more than 20%. In T-P and T-N, the effects of $CaO_2$ on them were overwhelming (50% or more) meanwhile that of the microbial agent on them was less than 20%. Also, $CaO_2$ influenced on the microbial flora: Desulfobvibrio thermophilus, a sulfate reducing bacterium decreased in number, considering the increase of pH and rise of redox potential. In contrast, Pseudomonas sp., Pseudoalteromonas sp., Pseudomonas aeruginosa were remarkably dominant over other species with mixed treatment as a PCA analysis confirmed it.

• Bulletin of the Korean Chemical Society
• /
• 제30권9호
• /
• pp.2043-2050
• /
• 2009

2′-$\beta$-C-Methylneplanocin A (3) was synthesized via 2-$\beta$-C-methylribonolactone, prepared by a modified Whistler and BeMiller’s method developed by our laboratory, as potential anti-HCV agent. Reduction of 14 with Dibal-H afforded 26 in a good yield with a trace of 25, whereas a Luche reduction gave 26/25 = 4/1 mixture. Several attempts were made to chemoselectively remove TBS group in the presence of TBDPS group and treatment with both PPTS and TsOH showed the best result. Condensation of 26 with 6-chloropurine under Mitsunobu conditions produced an $S_N$2 product 27 along with an $S_N$2′ product 28.

• 대한화학회지
• /
• 제11권4호
• /
• pp.159-164
• /
• 1967

균일계수 산화환원 적정에 있어서의 전위의 적정분율에 따른 변화을 나타내는 정확한 방정식을 얻었다. 이 방정식은 정정곡선이 시약의 농도에 무관계함을 알려준다. 또한 전위차적정범위 종말점의 예민도는 반전지의 기준전위의 차는 몰론, 각 반반응에 관여하는 전자수에 따라 심한 영향을 받음을 알려준다. 적정곡선의 변곡점이 당량점과 일치하지 않음을 증명하였다. 또한 적정단계에 따른 반응의 완결도를 평형상수식을 토대로 하여 해석하였다. 이 결과는 산화환원 이외의 평형에도 적용된다.

• 전기학회논문지
• /
• 제67권12호
• /
• pp.1641-1647
• /
• 2018

In this paper, we describe a portable potentiostat which is capable of cyclic voltammetry(CV) and amperometry for electrochemical dissolved oxygen sensor. In addition, this portable potentiostat can also transmit the measured data wirelessly to android devices such as smart phone, tablet, etc. through Bluetooth. The potentiostat system consists of three parts; a voltage generator circuit which is controlled by Arduino nano and 12-bit DAC(digital to analog converter) to generate necessary electric potential for operating the electrochemical sensor, an oxidation/reduction current measurement circuit, and a Bluetooth module to transmit data wirelessly to an android device. Once measurements are carried out with the android application, the measured data is transmitted to the android device via Bluetooth and displayed using the android app. in real time. In this paper, we report the measured reduction current with a fabricated dissolved oxygen sensor in both saturated-oxygen state and zero-oxygen states. The results of the developed portable potentiostat system are in good agreement with those of the commercial portable potentiostat (${\mu}stat200$, Dropsens inc.). The measured peak reduction currents using the developed potentiostat and the commercial ${\mu}stat200$ potentiostat were $-0.755{\mu}A$ and $-0.724{\mu}A$, respectively. The reduction currents measured at zero-oxygen state were $-0.005{\mu}A$ and $-0.004{\mu}A$. The discrepancy between those two systems seems very small, which implies successful development of a portable and wireless potentionstat.

• 전기화학회지
• /
• 제12권1호
• /
• pp.54-60
• /
• 2009

The redox characteristics of 2-arylaldehydehydrazono-3-phenyl-5-substituted-2, 3-dihydro-1, 3, 4-thiadiazoles (1a-h) have been investigated in nonaqueous solvents such as 1, 2-dichloroethane (DCE), dichloromethane (DCM), acetonitrile (AN), Tetrahydrofuran (THF), and dimethylsulfoxide (DMSO) at platinum electrode. Through controlled potential electrolysis, the oxidation and reduction products of the investigated compounds had been separated and indentified. The redox mechanism had been suggested and proved. It had been found that all the investigated compounds were oxidized in two irreversible one-electron processes following the well-known pattern of The EC-mechanism; the first electron loss gives the corresponding cation-radical which is followed by proton removal from the ortho-position in the N-phenyl ring forming the radical. The obtained radical undergoes a second electron uptake from the nitrogen in the N = C group forming the unstable intermediate (di-radical cation) which undergoes ring closure forming the corresponding cation. The formed cation was stabilized in solution through its combination with a perchlorate anion from the medium. On the other hand, these compounds are reduced in a single two-electron process or in a successive two one-electron processes following the well known pattern of the EEC-mechanism according to the nature of the substituent; the first one gives the anion-radical followed by a second electron reduction to give the dianion which is basic enough to abstract protons from the media to saturate the (C = O) bond.

• 대한환경공학회지
• /
• 제38권9호
• /
• pp.521-527
• /
• 2016

나노 영가철은 산화환원기작을 통하여 염소계 유기화합물과 같은 물질을 효과적으로 처리할 수 있다고 알려져 있지만, 작은 사이즈로 인하여 회수가 어려운 단점으로 인하여 실제 수처리 공정에서는 유출 등의 우려로 널리 적용되지 못하였다. 이와 같은 한계를 극복하기 위하여 활성탄과 같은 담체에 고정화 하여 사용하는 연구가 활발히 진행되었다. 본 연구에서는 활성탄에 영가철의 고정화 시 대표적으로 사용되는 고온 및 상온의 두 가지 경로에 대해 평가하였으며, 결과를 바탕으로 최적의 합성 조건을 도출하였다. 효과적인 나노영가철/입상활성탄 복합체를 합성하기 위해서는 높은 철 함량과 더불어 영가철의 분율을 높이는 것이 중요하며, 이를 위해서는 합성 과정에서 형성되는 철 산화물 및 수산화물의 형성을 억제하는 것이 중요한 것으로 나타났다. 또한 영가철의 분율을 높이기 위한 환원 시간 및 중간 건조 과정의 유무 등 합성 조건의 영향을 살펴보았으며, 그 결과 중간 건조 과정 없이 바로 $NaBH_4$를 이용한 환원 조건을 약 2시간 이상 유지하는 것이 최적 조건임을 확인하였다. 합성된 나노영가철/입상활성탄 복합체는 활성탄의 흡착 능력과 영가철의 환원 능력을 동시에 보유함으로써 나이트로벤젠과 같은 환원이 가능한 오염물질의 제거에 효과적으로 나타났다.