• Korean Chemical Engineering Research
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• 제44권1호
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• pp.92-96
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• 2006

유기용매에서 효소를 이용하면 다양한 선택적 반응을 쉽게 수행할 수 있어 산업적 적용 가능성이 매우 높지만, 효소의 안정성 저하는 아직까지 큰 문제 중의 하나로 남아있다. 유기용매에서 효소 반응시 효소의 실활 원인과 효소의 안정화 방법 연구를 위하여 단백질의 folding에 관여하는 molecular chaperone의 일종인 heat-shock protein Hsp90을 이용하여, 대표적인 유기용매 반응시스템에서의 과산화효소 HRP 안정성 향상 연구를 수행하였다. 그 결과 Hsp90은 30％ DMSO, 30％ 및 50％ dioxane 완충용액에서 HRP의 실활 방지 효과를 보였고, 실활된 효소의 재생에도 탁월한 효과를 보였다. 그리고 형광분석과 CD(circular dichroism)에 의한 구조분석을 수행하여 Hsp90이 유기용매에 의해 unfolding되어 있는 효소를 다시 refolding하는 데 기여함을 알았다.

• 대한화학회지
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• 제53권3호
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• pp.325-334
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• 2009

유기용매들에 대한 내성을 갖고 분해할 수 있는 능력을 가진 박테리아가 해수에서 단리되었지만, 해양조건에서 유기용매가 분해될 때 그들의 역할은 잘 알려져 있지 않았다. 콘스탄차 해수에서 단리된 Aeromonas hydrophila IB$B_{ct4}$는 여러 다른 종류의 유기용매들에 대하여 내성을 갖고 분해할 수 있는 능력을 가지고 있다. 옥탄올-헥산 혼합물에서 2.64 - 3.17 사이의 분배계수지수 (log $P_{ow}$)를 가진 톨루엔, 크실렌 이성질체들 및 에틸벤젠은, 3.69 - 4.39 사이의 log $P_{ow}$를 가진 프로필벤젠, n-헥산 및 n-헵탄보다 이들 박테리아에 더 독성이 있었다. Aeromonas hydrophila IB$B_{ct4}$에 유기용매들을 처리하였을 때 분자수준에서 세포의 변형이 유발되었다. 다른 유기용매들에 의하여 분자수준에서의 세포변화가 다르게 나타난다는 것을 밝힌 이 연구는 배양 조건에서 유기용매에 대한 박테리아 세포들의 반응이 복잡하다는 것을 보여 주고 있다.

• 한국농공학회지
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• 제40권2호
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• pp.102-111
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• 1998

Large amount of sludge have been generating in the process of water and wastewater treatment in urban area, and it has been making many environmental problems. Currently almost of sludge is landfilled, and since sludge is difficult to handle and dehydrate, the permeated water from the filled-in ground contaminate the surrounding soil and groundwater which may cause serious environmental and sociological problems. The organic component in sludge can be almost removed through the heat treatment process, and the final product is called artificial soil or artificial media according to the temperature control. To produce artificial media using sludge, chabazite and lime were used as an additive, and the mixture of sludge & additives was thermally treated in the firing kiln at about 800~1, 100。C for about fifteen minutes. The physical and chemical characteristics of the produced artificial media were analyzed, and it showed that it can be used as an artificial media for plant production or soil conditioner for farmland. The concentrations of the toxic heavy metals in the artificial media were lower than the soil quality standard for farmland. The characteristics of produced artificial media, using the mixture of sludge and additives through the heat treatment, is similar to the natural chabazite and soil. The analyzed result of the mineral composition of artificial media showed that it has a characteristics similar to natural stable soil, so the produced artificial media may be applied to farmland or water culture without causing adverse effect. Therefore this study showed that the above process can be a feasible alternative for sludge treatment.

• Rapid Communication in Photoscience
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• 제4권3호
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• pp.70-72
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• 2015

Oligomers of p-phenylene vinylene and its derivatives have drawn much attention due to their unusual emission characteristics of showing increased emission when they form into nanoparticles. We have investigated the optical properties of the oligo-(p-phenylene vinylene) and its cyano-substituted derivatives in solution and in nanoaggregate media by femtosecond and picosecond time resolved fluorescence as well as stationary spectroscopies. All the spectroscopic data are consistent with the conclusion that the cyano substitution on the ${\beta}$-position of oligo-(p-phenylene vinylene) leads to breakage of the otherwise planar structure of cyano-unsubstituted molecules, which opens up an extremely efficient, as fast as 100 fs, non-radiative relaxation channel of the excited state. Formation of the nanoaggregates reverts the effect to make the molecules planar and to block the non-radiative relaxation channel. Therefore, concerning the applications in organic electroluminescent devices and organic light emitting diodes, substitution by the cyano group is not advantageous, although such modification should be useful in respect of controlling fluorescence intensity in different media.

• 한국물환경학회지
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• 제22권1호
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• pp.45-50
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• 2006

This study was performed to evaluate the air lift reactors (ALR) by variations of HRT and recycling rate. Air lift reactor was composed of bioreactor and clarifier above it. To remove organic matters and nitrogen through the formation of microbic film and filtration, bio-filter reactors were filled with clay, glass, bead, waste plastic, respectively. Influent wastewater was fed to biofilter reactor, and effluent wastewater from bio-filter reactor was injected ALR again, instead of adding external carbon source. Effluent BOD concentration was satisfied with lower than 10 mg/L in recycling rate 100% regardless of the variation of HRT and the kinds of media materials. In HRT 4 hr, recycling rate 100%, BOD removal efficiency rate was from about 85 to 90%, COD removal efficiency rate was higher than 90%. Effluent TN concentration was satisfied with less than 20 mg/L, if HRT was maintained by over than 6 hr regardless of recycling rate and media materials. Over than HRT was 4 hr, microbes concentration in air lift reactor was maintained over than 2,500 mg/L constantly, not sensitive to environmental condition, and organic removal was effective as it was higher.

• Journal of Microbiology and Biotechnology
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• 제20권5호
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• pp.950-957
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• 2010

Serratiopeptidase (SRP), a 50 kDa metalloprotease produced from Serratia marcescens species, is a drug with potent anti-inflammatory property. In this study, a powerful statistical design, evolutionary operation (EVOP), was applied to optimize the media composition for SRP production in shake-flask culture of Serratia marcescens NRRL B-23112. Initially, factors such as inoculum size, initial pH, carbon source, and organic nitrogen source were optimized using one factor at a time. The most significant medium components affecting the production of SRP were identified as maltose, soybean meal, and $K_2HPO_4$. The SRP so produced was not found to be dependent on whey protein, but rather was notably induced by most of the organic nitrogen sources used in the study and free from other concomitant protease contaminant, as revealed by protease inhibition study. In addition, experiments were performed using different sets of EVOP design with each factor varied at three levels. The experimental data were analyzed with a standard set of statistical formula. The EVOP-optimized medium, with maltose 4.5%, soybean meal 6.5%, $K_2HPO_4$ 0.8%, and NaCl 0.5% (w/v), gave a SRP production of 7,333 EU/ml, which was 17-fold higher than the unoptimized media. The application of EVOP resulted in significant enhancement of SRP production.

• Journal of Preventive Medicine and Public Health
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• 제45권6호
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• pp.335-343
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• 2012

Mercury is emitted to the atmosphere from various natural and anthropogenic sources, and degrades with difficulty in the environment. Mercury exists as various species, mainly elemental ($Hg^0$) and divalent ($Hg^{2+}$) mercury depending on its oxidation states in air and water. Mercury emitted to the atmosphere can be deposited into aqueous environments by wet and dry depositions, and some can be re-emitted into the atmosphere. The deposited mercury species, mainly $Hg^{2+}$, can react with various organic compounds in water and sediment by biotic reactions mediated by sulfur-reducing bacteria, and abiotic reactions mediated by sunlight photolysis, resulting in conversion into organic mercury such as methylmercury (MeHg). MeHg can be bioaccumulated through the food web in the ecosystem, finally exposing humans who consume fish. For a better understanding of how humans are exposed to mercury in the environment, this review paper summarizes the mechanisms of emission, fate and transport, speciation chemistry, bioaccumulation, levels of contamination in environmental media, and finally exposure assessment of humans.

• 한국버섯학회지
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• 제5권1호
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• pp.43-49
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• 2007

이상의 결과를 종합하면, 평가대상 토양을 증류수로 20배 희석하여 200rpm 으로 30분간 진탕한 후 PDA (감자추출배지)와 혼합하여 $121^{\circ}C$에서 20분간 살균한 후 Coriolus hirsutus (MKACC 50560) 균을 접종한다. 접종완료 후 $25^{\circ}C$에서 5일간 배양한 후 균사 생장을 측정하여 담자균의 균사 생장률 (목적토양에서의 균사생장/PDA 에서의 균사생장${\times}100$)을 계산한다. 이 기준에 따라 균사생장률이 60%이상이 되면 대상 토양은 작물 생육에 적합한 토양이라고 추정할 수 있다. 이러한 방법은 토양의 건전성 평가를 위한 신속한 간이검사를 통하여 소량의 시료를 가지고 단기간 내 대량 분석을 가능하게 하여 토양 건정성 평가의 기초 자료로 사용될 수 있다고 사료된다.

• 해양환경안전학회지
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• 제28권5호
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• pp.712-720
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• 2022

본 연구는 극지 식물플랑크톤의 자외선 영향을 파악하기 위해, Phaeocystis antarctica와 Phaeocystis pouchetii를 대상으로 유색 용존 유기물의 생산과 광반응성을 평가하였다. 강한 자외선에 노출 배양 시, 가시광선 파장대에서 유색 용존 유기물의 흡광도는 두 식물플랑크톤 모두 배양 초기에 비해 48시간 동안 감소하였다. 반면, 자외선 파장에서는 P. antarctica는 48시간 배양 후, 유색 용존 유기물의 흡광도는 초기 농도에 비해 약 30% 감소하였지만, P. pouchetii의 흡광도는 오히려 10% 증가한 경향을 보였다. 이 결과들은 강한 자외선에 노출될 경우, P. antarctica이 생산한 유색 용존 유기물은 광분해에 의한 감소로 인해 해수 중 수중 생태계에 자외선 차단 효과는 감소하는 반면, P. pouchetii가 생산한 유색 용존 유기물에 의한 광보호 효과가 더 효율적임을 알 수 있었다. 또한, 자외선 영향 하에서 배양된 P. pouchetii의 배양액에서 시간에 따라 증가한 유색 용존 유기물의 형광 특성이 지구 거대물질로 알려진 humic-like (C-peak)와 일치하여, 이는 자외선 차단 물질로 알려진 MAAs 생물 생산에 의한 것임을 확인하였다. 이는 기후변화에 의한 성층화가 강화되는 극지 해양환경에서, 광반응성이 낮은 P. pouchetti가 용존 유기물의 증가에 기여할 수 있을 것으로 기대된다.

• 환경위생공학
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• 제10권3호
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• pp.1.1-15
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• 1995

This study was performed to estimate the characteristics of the organic wastewater treatment and bed porosity with the circulation velocity in the anaerobic fluidized bed biofilm reactor. The results were as follows; 1. With Increasing circulation velocity the fluidized bed expanded smooth and with increasing initial particle volume the fluidized bed was increased. 2. With increasing circulation velocity the gasproduction was increased, but at 1.Scnt/sec of circulation velocity AFBBR showed the highest value of methane production rate per removed COD. Therefore, for the purpose of economical operation in AFBBR, 1.5cm/sec of circulation velocity was optimum 3. The microorganisms were colonized in the crevice of the media. 4. On fluidization, COD, VA,55 profiles with the reactor height were not showed. In conclusion, AFBBR suit the organic wastewater treatment's purpose, and at 1.5cm/sec of circulation velocity the system is economical in an energy Point of view.