Abstract Systematic optimization of the photocatalyst and investigation of the role of each component is important to maximizing catalytic activity and comprehending the photocatalytic conversion of CO 2 reduction to solar fuels. A surface‐modified Ag@Ru‐P25 photocatalyst with H 2 O 2 treatment was designed in this study to convert CO 2 and H 2 O vapor into highly selective CH 4 . Ru doping followed by Ag nanoparticles (NPs) cocatalyst deposition on P25 (TiO 2 ) enhances visible light absorption and charge separation, whereas H 2 O 2 treatment modifies the surface of the photocatalyst with hydroxyl (–OH) groups and promotes CO 2 adsorption. High‐resonance transmission electron microscopy, X‐ray photoelectron spectroscopy, X‐ray absorption near‐edge structure, and extended X‐ray absorption fine structure techniques were used to analyze the surface and chemical composition of the photocatalyst, while thermogravimetric analysis, CO 2 adsorption isotherm, and temperature programmed desorption study were performed to examine the significance of H 2 O 2 treatment in increasing CO 2 reduction activity. The optimized Ag 1.0 @Ru 1.0 ‐P25 photocatalyst performed excellent CO 2 reduction activity into CO, CH 4 , and C 2 H 6 with a ~95% selectivity of CH 4 , where the activity was ~135 times higher than that of pristine TiO 2 (P25). For the first time, this work explored the effect of H 2 O 2 treatment on the photocatalyst that dramatically increases CO 2 reduction activity.
영산도는 전남 신안군 흑산면에 속하며 다도해해상국립공원과 신안-다도해 유네스코 생물권보전지역에 포함된다. 세계식물구계 구분에서 중일구계, 온대아구계, 한반도구에 속하며, 한반도 관속식물 분포상 후박나무, 구실잣밤나무, 붉가시나무 등 상록성 식물의 분포한계인 흑산도, 남해안 등 여러 섬이 포함된 남해안아구에 속한다. 현재까지 문헌조사를 통한 영산도에 자생하고 있는 환경부 지정 멸종위기 야생식물은 Ⅰ급 풍란과 Ⅱ급 석곡, 2분류군으로 나타났으나 본 연구를 통해 멸종위기 야생생물 Ⅱ급 혹난초가 자생하는 것으로 밝혀졌다. 섬 중앙부의 문암귀운과 얼굴바위 주변에서 총 4지점, 약 370개체군의 혹난초를 발견하였고, 착생기질과 주요 서식특성 분석을 통해 영산도 혹난초의 서식특성을 파악하였다. 더불어 영산도에 분포하는 멸종위기 야생식물에 대한 전수조사를 통해 기 알려진 풍란 1집단과 석곡 약 1000개체의 분포를 확인하였다. 영산도에 분포하고 있는 멸종위기 야생식물들은 대부분 인간의 접근이 불가능한 절벽사면 등에 분포하고 있어 인위적인 훼손위협은 낮은 것으로 판단되었다. 하지만 섬의 특성상 좁은 면적에 다수의 멸종위기 야생식물이 함께 분포하고 있어서 일부 식물의 자생지가 노출된다면 다수의 멸종위기 야생식물들이 불법적으로 훼손될 가능성이 있는 것으로 나타났으며, 방목염소에 의한 수목피해, 높아지는 귀화식물 점유율 등 환경훼손에 따른 위협은 지속적으로 증대하고 있는 것으로 판단되었다. 이에 따라 멸종위기 야생식물의 지속적인 관리와 모니터링, 섬 전체에 대한 특정도서, 생태경관보호구역 지정 등 정부 차원의 지속적인 관리를 포함한 현지 내· 외를 구분 짓지 않는 적극적인 보전 대책이 필요한 것으로 판단되었다.
Abstract O-GlcNAc transferase (OGT) is an enzyme that catalyzes the O-GlcNAc modification of nucleocytoplasmic proteins and is highly expressed in many types of cancer. However, the mechanism regulating its expression in cancer cells is not well understood. This study shows that OGT is a substrate of the E3 ubiquitin ligase X-linked inhibitor of apoptosis (XIAP) which plays an important role in cancer pathogenesis. Although LSD2 histone demethylase has already been reported as an E3 ubiquitin ligase in lung cancer cells, we identified XIAP as the main E3 ubiquitin ligase in colon cancer cells. Interestingly, OGT catalyzes the O-GlcNAc modification of XIAP at serine 406 and this modification is required for the E3 ubiquitin ligase activity of XIAP toward specifically OGT. Moreover, O-GlcNAcylation of XIAP suppresses colon cancer cell growth and invasion by promoting the proteasomal degradation of OGT. Therefore, our findings regarding the reciprocal regulation of OGT and XIAP provide a novel molecular mechanism for controlling cancer growth and invasion regulated by OGT and O-GlcNAc modification.
Photocatalytic CO2 reduction is a potential technique for converting solar energy and greenhouse gases into value-added-chemicals. However, limited light absorption and poor charge separation of electron-hole pairs are the main obstacles. Here, we have developed a highly stable, phase-controlled heterostructured photocatalyst of molybdenum sulfide with reduced titania (1T/2H-MoS2@RT) for CO2 reduction into CO. The optimized 1T/2H-MoS2@RT produced 1.02 μmol g−1 h−1 (1480.1 ppm g−1 h−1) of CO. The catalyst showed ∼5 and ∼19 times higher activity than RT and MoS2, respectively, and excellent stability over 48 h (8 cycles). Our investigation revealed that the combination of phase-controlled MoS2 with RT synergizes the selective conversion of CO2 to CO. MoS2 acts as a visible light sensitizer and electron transport bridge; however, RT extracts electrons from MoS2 because of its lower energy potential. Improved light absorption, CO2 adsorption, and rapid electron-hole separation are responsible for the increased catalytic activity and stability.
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