본 연구에서는 연료극 또는 공기극에 함유된 불순물인 황화합물의 도입을 차단할 수 있는 GDL을 제조하여, 이를 평가용 단위전지에 체결하여 H2S와 SO2를 연료극과 공기극에 각각 동시에 공급하여 PEMFC의 성능 저하 및 회복에 관한 연구를 수행하였다. 그 결과 H2S와 SO2의 농도가 증가함에 따라 전지의 성능이 감소하며 특히 10 ppm 이상의 농도에서는 10분 이내에 약 10-15% 정도 성능이 감소하였다. 특히 GDL 표면의 기공이 없는 CN-2 GDL을 체결한 단위전지의 경우 피독에 의한 성능 감소 속도가 더 빠른 것을 확인하였다. 그리고 단위전지 피독 후 황화합물이 혼합되지 않은 순수 가스를 1시간 이상 공급하였을 때 전지의 성능이 GDL의 종류에 따라 90%에서 95% 이상 회복되며 CN-1 GDL의 경우가 가장 회복이 우수하였다.

최근 산림분야를 통해 탄소배출량을 줄이고자하는 노력으로 신규 및 재조림이 주를 이루던 산림정책 패러다임이 산림전용 및 산림황폐화방지를 통한 탄소배출감축(REDD) 활동에 대한 관심으로 집중되고 있다. 이에 따라 REDD 이행 성과 가시화를 위한 단계적 연구가 진행되고 있다. 본 연구는 한국의 16개 시도단위별 산림환경여건을 분류하고, 국제적으로 주요하게 사용되는 6가지 기저선 접근법을 적용하여 국가단위 REDD 프로그램 운영을 위한 최적 기저선 접근법을 도출하였다. 연구결과 일반적으로 HFLD에 대한 탄소배출권 획득량이 낮았으며, 이에 반해 LFMD, LFHD에 대한 획득량은 높게 나타났다. 이에 따라 HFLD 지역은 산지전용을 통한 개발이 더 많은 경제적 이익을 가져올 수 있기 때문에 REDD 이행 기제에 대한 참여 유인이 부족하게 된다. 모든 유형의 산림여건에서 REDD에 대한 참여를 높이기 위한 유인성과 적은 노력으로 많은 양의 탄소배출권을 획득하는 일이 발생하지 않는 실제성이 모두 적절하게 만족스러운 기저선 접근법이 필요하다. 이러한 실제성과 유인성 평가시 Corridor Approach 접근법 선택이 가장 합리적인 것으로 판단되며, 국내 적용시 발생하는 이익분배에 대한 단점을 보완하기 위해 한국형 Corridor Approach 접근법을 개발하였다.

It is well established that mitochondrial genome is strictly maternally inherited in mammalian, despite the fact that paternal mitochondria enter into oocyte during fertilization. To date, although some mechanisms have been extrapolated to interpret the elimination of paternal mitochondria, the exact mechanism still is unclear. Recent studies suggest that autophagy process and the ubiquitin-mediated degradation pathway may be involved in elimination of paternal mitochondria. However, the dynamic profiles of autophagy and ubiquitination associated with paternal mitochondria degradation have not been determined in mouse model. Through immunostaining with specific antibody LC3 and Ubiquitin and confocal microscopy, we investigated the dynamic profiles of LC3 and Ubiquitin signals in mouse embryos during preimplantation development. In addition, embryos were stained with MitoTracker Red for tracking the degradation process of paternal mitochondria. Our results showed that paternal mitochondria gradually degraded during postfertilization development, and sporadic paternal mitochondria were found at least in 16 cell embryos. LC3 and Ubiquitin signals appeared in the midpiece of sperm at 3 h postfertilization, and they were strictly colocalizated with paternal mitochondria from zygote to 2 cell embryo. Nevertheless, the colocalization became loose at 4 cell embryos, and gradually disappeared beyond 4 cell embryos. Our results confirmed that autophagy process and the ubiquitin-mediated degradation pathway may take part in the postfertilization remove of paternal mitochondria.

This study was conducted to investigate the effects on in situ ruminal degradation of feed protein sources (soybean meal, P-SBM; dried distillers grain with solubles, P- DDGS; wheat bran, P-WB) treated with protease as compared with conventional feed protein sources (soybean meal, SBM; dried distillers grain with solubles, DDGS; wheat bran, WB). There was no significant change in the chemical composition and amino acid profiles of enzyme treatment protein sources compared with the non-treated groups (p<0.05). But for treatment groups, the solid content and total amino acids were reduced by increasing the moisture content due to proteolytic conditions. On the entire incubation time in situ ruminal degradation rate of dry matter appeared higher in treatment groups compared to control groups (p<0.05), and that of the treatment groups suspended during 48 hours were in the order of P-SBM (97.70%), P-WB (74.26%) and P- DDGS (72.39%). In particular, DM degradation rate of enzyme treated DDGS significantly increased to 43.62%, 45.99%, 55.97%, 69.87% and 72.39%, respectively, incubated during 3, 6, 12, 24 and 48 hours in rumen (p<0.05). Also protein degradation rate of P-WB and P-SBM significantly decreased compared to their respective non-treated sources; however, by contrast, in DDGS it was increased. For P-SBM, protein degradation rate significantly decreased at 6 and 12 hours, and for P-DDGS it was increased at 3 and 6 hours of suspension times in rumen (p<0.05). In particular, protein degradation rate of enzyme treated group suspended for 48 hours were in the order of P-SBM (91.81%), P-WB (86.36%) and P-DDGS (58.87%). This result suggests that protease treatment of feed protein sources might be utilized to increase the bypass ratio into post-rumen for wheat bran, soybean meal, and to improve the utilization of feed protein.

Hydroxyapatite (HAp) powders with different crystallinities were synthesized at various calcination temperatures through the co-precipitation of Ca(OH)2 and H3PO4. The degradation behavior of these HAp powders with different crystallinities was assessed in a simulated body fluid solution (SBF) for 8 weeks. Below 800˚C, the powders were nonstochiometric HAp, and the single HAp phase was successfully synthesized at 800˚C. The degree of crystallinity of the HAp powders increased with an increasing calcination temperature and varied in a range from 39.6% to 92.5%. In the low crystallinity HAp powders, the Ca and P ion concentrations of the SBF solution increased with an increasing soaking time, which indicated that the low crystallinity HAp degraded in the SBF solution. The mass of the HAp powders linearly decreased with respect to the soaking time, and the mass loss was higher at lower crystallinities. The mass loss ranged from 0.8% to 13.2% after 8 weeks. The crystallinity of the HAp powders increased with an increasing soaking time up to 4 weeks and then decreased because of HAp degradation. The pH of the SBF solution did not change much throughout the course of these experiments. These results suggested that the crystallinity of HAp can be used to control the degradation.

Many basidiomycetes, especially mushroom species, thrive on saccharides that they obtain from the decomposition of cellulose, hemi-cellulose and or lignin. Cellulose is degraded by specific enzymes called cellulases. Cellulases play an important role in the biosphere by recycling cellulose, the most abundant carbohydrate produced by plants. Also cellulases have many potential biotechnologic and industrial applications. Detection of cellulose degrading activity is commonly performed on carboxymethylcellulose CMC medium in combination with a stain that reveals the degraded CMC. In order to efficiently screen the F. velutipes knockout library, obtained through Agrobacterium-mediated transformation (ATMT), for those important enzymes we compared two different staining methods i.e. Congo Red and Gram’s Iodine (as reported in R. C. Kasana et al 2008). The latter stain showed strongly enhanced detection in time and intensity, facilitating mass screening of our mutant database. Using Gram’s iodine and square petri dishes containing up to 9 colonies at a time we can now rapidly screen multiple mutants in a short period. We are going to find the genes. Inactivated genes of mutants with altered cellulase degradation activity will be identified and cloned for further analysis.

The photodegradation of the model compounds Quinol, an aromatic organic compound and Acid blue FFS, an acid dye of chemical class Triphenylmethane was studied by using illumination with UV lamp of light intensity 250W. TiO2 and TiO2 doped with Boron and Nitrogen was used as catalyst. The sol-gel method was followed with titanium isopropoxide as precursor and doping was done using Boron and Nitrogen. In photocatalytic degradation, TiO2 and doped TiO2 dosage, UV illumination time and initial concentration of the compounds were changed and examined in order to determine the optimal experimental conditions. Operational time was optimized for 360 min. The optimum dosage of TiO2 and BN doped TiO2 was obtained to be 2 mgL-1 and 2.5 mgL-1 respectively. Maximum degradation % for quinol and Blue FFS acid dye was 78 and 95 respectively, at the optimum dosage of BN-doped TiO2 catalyst. It was 10 and 4% higher than when undoped TiO2 catalyst was used.

Many researchers reported biodegradation of environmental pollutants by white-rot fungi. Toward in situ bioremediation, we have investigated biodegradation of environmental pollutants by litter-decomposing fungi. In our results, lignin-degrading enzymes produced from litter-decomposing fungi are thought to participate in degradation of pentachlorophenol (PCP) and 2,4-dichlorophenoxy acetic acid (2,4-DA). Then, we examined the biodegradation of PCP, 2,4-DA and the analogs of 2,4-DA by purified laccase and the role of redox mediator on laccase reaction. Laccase purified from Calvatia craniiformis decomposed phenolic compounds, PCP and 2,4-dichlorophenol (2,4-DP), but not non-phenolic compounds, 2,4-DA and 2,4-dichlorophenoxy ethanol (2,4-DE), even in the presence of redox mediators. To clarify the reaction mechanism between the substrates and redox mediators, quantum chemical analysis was applied using MOPAC 2009 and Gaussian 03. The results of the heat of formation and the perturbation energy showed that even redox mediator radicals could not oxidize the non-phenolic compounds. Previously several reports showed that laccase-redox mediator systems decomposed non-phnolic compounds, but we propose that the system could not react on the chlorinated aromatic compounds based on the result of quantum analysis.

The genes encoding cellulases, which belong to glycosyl hydrolase families have been cloned from the basidiomycetous mushrooms. The transcripts of cellulase genes are strongly induced when the mycelia are grown in medium containing crystalline cellulose, and they are not expressed in medium containing glucose, but how insoluble substrates such as microcrystalline cellulose are recognized by these fungal cells is not clear. The polypore mushroom Polyporus arcularius is a wood-decomposing basidiomycete that produces at least three types (I, II, and IIIa) of carboxymethyl cellulase (CMCase) when the medium contains crystalline cellulose as the sole carbon source and produced mainly cellobiose in the medium. The genomic and cDNA clones encoding the family 12 endoglucanase (CMCase IIIa) gene (cel3A) of P. arcularius have been sequenced, and Cel3A has been expressed as an active enzyme in Escherichia coli. To determine the role and function of each type of cellulase in the degradation of crystalline cellulose by basidiomycetous mushrooms, the structure of all of the cellulase genes should be investigated, but the nucleotide sequences of the other cellulase genes in P. arcularius have not yet been reported. In the current study, the genomic and cDNA clones encoding the endoglucanases (cel4), and the two cellobiohydrolases (cel1 and cel2) of P. arcularius sequenced and characterized. The predicted amino acid sequence of Cel1 Cel2, Cel3a and Cel4 are similar to glycosyl hydrolase family 7, 6 12 and 5 protein, respectively. The expressions of the all cellulase genes (cel1 cel2, cel3a and cel4) were induced by Avicel (microcrystalline cellulose) and cellopentaose but repressed by glucose, cellobiose, cellotriose, and cellotetraose. There was a low level of transcription of both genes regardless of the carbon source. These results suggest that P. arcularius cells constitutively express a very low level of cellulase that can degrade insoluble crystalline cellulose and that the transcription of celluases in the cells is induced by products produced by these endoglucanases such as cellooligosaccharides. From our findings, we propose a possible mechanism for the recognition and degradation of insoluble crystalline cellulose by fungal cells.

우리나라 토양으로부터 분리된 (주와 김 2009) poly (butylene succinate-co-butylene adipate; PBSA) 분해균 Burkholderia cepacia PBSA-7, Bacillus licheniformis PBSA-8 및 Burkholderia sp. PBSA-9에서 PBSA 분해효소를 암호화하는 유전자를 분석하였다. PCR을 수행하여 B.cepacia PBSA-7과 Burkholderia sp. PBSA-9는 약

Two pesticides commonly used in spinach were subjected to a field residue trial to ensure safety of terminal residues in the harvest. The residual patterns of two pesticides, which were Azoxystrobin and chlorpyrifos were examined after applying with the recommended dose and their DT50 were calculated. Also degradation patterns of pesticides at storage 4℃ were compared to those at 20℃, and removal rates of pesticides by washing spinach with water were measured. Biological half-lives of azoxystrobin and chlorpyrifos were 3.2~3.8 and 3.8~4.7 days, respectively. During the storage period, the degradation patterns were appeared more obviously at 20℃ than 4℃. Removal rates of azoxystrobin and chlorpyrifos were 9.6~90.0% and 17.7~85.8% by various washing methods.

Low temperature degradation behavior in yttria stabilized tetragonal zirconia polycrystal (Y-TZP) ceramics was microscopically observed from the phase contrast between monoclinic surface and tetragonal matrix. The degradation behavior was dependent on the surface treatment of sintered Y-TZP, even if the sintering history is same. In the mirror polished specimen, the monoclinic layer appeared in a uniform thickness from the surface. On the contrary, for the specimen with coarse scratch, the thickness of degraded surface was more than double especially from the coarse scratch. Since the scratch results in local deformation, the residual stress should be induced around the scratch. With the transformation from tetragonal to monoclinic, the volume expansion exerts a stress on a neighboring grains and promotes a successive phase transformation. Such a autocatalytic effect can be triggered from the part of coarse scratch.

Methylene blue (MB) was degraded by TiO2 and ZnO deposited on an activated carbon fiber (ACF) surface under UV light. The ACF/TiO2 and ACF/ZnO composites were characterized by BET, SEM, XRD, and EDX. The BET surface area was related to the adsorption capacity for composites. The SEM results showed that titanium dioxide and zinc oxide are distributed on the ACF surface. The XRD results showed that the ACF/TiO2 and ACF/ZnO composites contained a unique anatase structure for TiO2 and a typical hexagonal phase for ZnO respectively. These EDX spectra showed the presence of peaks of Ti element on ACF/TiO2 composite and peaks of Zn element on the ACF/ZnO composite. The blank experiments for either illuminating the MB solution or the suspension containing ACF/TiO2 or ACF/ZnO in the dark showed that both illumination and the catalyst were necessary for the mineralization of organic dye. Additionally, the ACF/TiO2 composites proved to be efficient photocatalysts due to degradation of MB at higher reaction rates. The addition of an oxidant ([NH4]2S2O8) led to an increase of the degradation rate of MB for ACF/TiO2 and ACF/ZnO composites.