헤스페리딘(Hesperidin, HD)은 다양한 식물체에 존재하는, 강한 항산화 기능을 가진 대표적인 flavonoid의 일종이다. 본 연구에서는 수용성 HD인 Hesperidin glucoside(HDG)가 가지는 세포손상 회복, 항염증 인자억제 및 melanin 생성억제 활성을 세포수준에서 비교하였다. HDG는 HD에 당전이 효소반응 으로 제조되었으며, HD에 비해 20,000배 이상 수용해도가 증가되었다. HaCaT 세포주에 대한 세포독성은 HDG가 HD에 비해 월등히 낮았다. HD와 HDG는 모두 자외선 조사된 HaCaT 세포에서 세포생존율 회 복효과를 나타내었다. 또한 HD와 HDG는 세포내 산화질소(NO), 종양괴사인자-α(TNF-α) 및 인터루킨 -6(IL-6)과 같은 염증 매개체 및 cytokine을 감소시켰으며, HD 보다는 HDG의 효과가 다소 우수하였다. Melanoma B16F10 세포주를 이용한 melanin 형성능과 tyrosinase 저해활성을 측정한 결과, HD와 HDG 모두 효과를 나타내었으며 HDG가 약간 우수한 결과를 보였다. 결론적으로, HD의 당전이체인 HDG는 HD에 비해 동등이상의 세포손상 회복, 염증성 매개체 및 cytokine 억제능과 melanin 형성억제능을 나타내 었으며, HDG의 높은 수용성과 낮은 세포독성 등의 특성은 다양한 분야에서의 용도를 확대시킬 수 있을 것으로 보인다.

석유기반 플라스틱의 대체제인 폴리하드록시부틸레이트(polyhydroxybutyrate, PHB)의 기존 추출방법은 분자량 감 소 및 물성 변형을 일으킨다. 본 연구에서는 기능화 된 탄소나노튜브(carbon nanotube, CNT)를 부착한 돌기형 탄소나노튜브 분리막의 여과를 통해 물리적 파쇄를 발생시켜 미생물 내 축적된 PHB를 추출하고자 하였다. 돌기형 탄소나노튜브 분리막의 물리적 파쇄를 확인하기 위해 대장균 용액으로 여과 실험을 수행하여 불활성화를 관찰하였다. 또한 PHB를 축적한 미생물 용 액의 여과를 수행하여 PHB가 추출되었는지 확인하였더니 가장 대표적인 추출방법인 chloroform과 비교하여도 여과로 인한 추출이 4% 높은 성능을 가진 것을 관찰하였다. 본 결과를 통해 친환경적 바이오 플라스틱 회수를 위한 돌기형 탄소나노튜브 분리막의 적용 가능성을 확인하였다.

The poor durability issue of polymer electrolyte membrane fuel cells is a major concern in terms of their commercialization. To understand the degradation mechanism of the catalysts, an accelerated durability test (ADT) was conducted according to the protocol established by internationally accredited organizations. However, reversible and irreversible factors contributing to the loss of activity have not yet been practically segregated because of the limitations of a batch-type three-electrode system, leading to the misunderstanding of the deactivation mechanism. In this study, we investigated the effect of a fresh electrolyte on the ADT and recovery process. When the fresh electrolyte was used at every range of the cycle, the chances of incorrect detection of dissolved CO and Pt ions in the electrolyte were very low. When the same electrolyte was used throughout the test, the accumulated Pt ions were deposited on the surface of the Pt nanoparticles or carbon support, affording an increased electrochemical surface area (ECSA) of Pt. Therefore, we believe that periodic replacement by a fresh electrolyte or a continuous-flow electrolyte is essential for the precise determination of the structural and electrochemical changes in Pt/C catalysts.

Polymer electrolyte membrane fuel cell (PEMFC) performance degrade when sulfur dioxide is present in the fuel hydrogen gas, this is referred as SO2 poisoning. This paper reveals SO2 poisoning on PEMFC cathode part by measuring electrical performance of single cell under 1 ppm and 5 ppm on SO2 gas operating. The security of SO2 poisoning depended on SO2 concentration under the best operating conditions(65℃ of cell temperature and 100% of relative humidity between anode and cathode). SO2 adsorption occured on the surface of catalyst layer on membrane electrode assembly (MEA), In addition, MEA poisoning by SO2 was cumulative but reversible. After poisoning within 5 ppm SO2 for 1hr, the electrical performance of PEMFC was found to recover up to about 93% by cyclic voltametry scan.

A mathematical model for the synergistic interaction of physical and chemical environmental agents was suggested for quantitative prediction of irreversibly damaged cells after combined exposures. The model took into account the synergistic interaction of

중추신경계는 일단 손상이 되면 손상된 세포의 재생, 손상된 수초의 회복, 신경계의 정상적인 연결 등의 제한성 때문에 그 회복이 매우 힘들다. 이러한 중추신경계의 중요한 손상으로는 다발성 경화증, 뇌졸중, 척수손상, 외상, 축삭의 탈수초화 등이 있다. 이전 연구들은 많은 발생빈도를 보이고 있는 척수손상에서 실질적인 척수의 기능적인 회복을 위해 손상된 척수신경의 재생과 축삭의 재수초화가 중요한 요인이라고 전하고 있다. 최근에는 이러한 척수손상에 대한 치료적 접근으로서 세포이식 기술이 하나의 해결책을 열어주고 있다. 따라서 본 논문에서는 척수손상의 특성을 살펴보고, 척수손상에 의한 기능장애에 대해 세포이식이 기능의 회복을 증진시킬 수 있다는 증거를 논의하고자 한다.

Potentially lethal damage repair (PLDR) in HFL-I was investigated by delayed plating experiments. The surviving fraction data were fitted to the linear Quadratic equation (LogSn=-nγ(αd+βd2) where γ=1 for immediate plating). And a repair factor γ was developed to compare survival for immediate and delayed plating . When we only took into account the repair factor of PLDR γ which was derived from the delay assay, the cell survival response th fractionated carbon ion irradiation was not fully matched. This gap suggested that consideration of another repair process is necessary. So this suggests that the various repair process plays an important role in the fractionated irradiations.

This study was performed to develop the biological treatment technology of wastewater polluted with heavy metals. Zinc-tolerant microorganism, such as Pseudomonas chlororaphis which possessed the ability to accumulate zinc, was isolated from industrial wastewaters polluted with various heavy metals. The characteristics of zinc accumulation in the cells, recovery of the zinc from the cells accumulating zinc, were investigated. Removal rate of zinc from the solution containing 100 ㎎/ℓ of zinc by zinc-tolerant microorganism was more than 90% at 48 hours after inoculation of the microorganisms. A large number of the electron-dense granules were found mainly on the cell wall and membrane fractions, when determined by transmission electron microscope. Energy dispersive X-ray spectroscopy revealed that the electron-dense granules were zinc complex with the substances binding heavy metals. The zinc accumulated into cells was not desorbed by distilled water, but more than 80% of the zinc accumulated was desorbed by 0.1M-EDTA. The residues of the cells after combustion at 550℃ amounted to about 21% of the dry weight of the cells. EDS analysis showed that the residues were comparatively pure zinc compounds containing more than 79% of zinc.