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Control of the oxidation state of copper in copper silicate SGU-29 for efficient catalytic reduction
Hyejin Yu,Hyun Sung Kim 대한화학회 2022 Bulletin of the Korean Chemical Society Vol.43 No.9
In transition metal-based zeotype systems, engineering transition metal species through ion exchange, doping, and oxidation state control to achieve heterogeneous catalytic systems is considered an effective strategy to improve catalytic performance. Among these strategies, controlling the oxidation state of transition metal species is a promising method to enhance the catalytic properties. Herein, we demonstrate for the first time that zeotypes containing Cu(I) can be effectively generated through the reduction of Cu(II) to Cu(I) in [CuO4]2? in the SGU-29 framework using a hydrogen/argon gas mixture. Our results showed that reduced SGU-29 (rSGU-29) exhibited a high catalytic performance while reducing 4-nitrophenol, providing 99% conversion.
Vegetables, but not pickled vegetables, are negatively associated with the risk of breast cancer.
Yu, Hyejin,Hwang, Ji-Yun,Ro, Jungsil,Kim, Jeongseon,Chang, Namsoo Lawrence Erlbaum Associates, Publishers [etc.] 2010 Nutrition and cancer Vol.62 No.4
<P>This study investigated the association between pickled vegetable consumption and the risk of breast cancer using a validated food frequency questionnaire. A total of 358 patients with breast cancer who were matched to 360 healthy controls by age (using a 5-yr age distribution) were recruited from the National Cancer Center in South Korea. After adjusting for nondietary risk factors, total vegetable intake was inversely associated with risk of breast cancer. However, unlike nonpickled vegetables, pickled vegetable intake and its proportion relative to total vegetables were positively associated with the risk of breast cancer, and this association was more profound and consistent when pickled vegetable intake was considered as a proportion relative to total vegetables (odds ratio [OR] = 6.24, 95% confidence interval [CI] = 3.55-10.97; P for trend <0.001 for highest vs. lowest quartiles of intake) than as the absolute consumed amount (OR = 2.47, 95% CI = 1.45-4.21; P for trend = 0.015 for highest vs. lowest quartiles of intake). These results suggest that not only the amount of total vegetable intake but also the amounts of different types of vegetable (i.e., pickled or nonpickled) and their proportions relative to total vegetables are significantly associated with the risk of breast cancer.</P>
유혜진(Hyejin Yu),오근엽(Keun-Yeob Oh),조원준(Wonjun Cho),임옥택(Oktaeck Lim) 한국가스학회 2021 한국가스학회지 Vol.25 No.1
세계적으로 천연가스는 환경적, 정치적, 지역적인 이유로 중요한 에너지원으로 부상하고 있다. 우리나라에서 천연가스는 액화천연가스로 수입하고 있으며, 석탄과 원전을 대체하는 연료나 원료의 활용에서 액화천연가스는 증가하고 있다. 우리나라는 천연가스를 수입에 의존하고 있기 때문에 공급에 대한 안정성분석이 중요하다. 따라서, 본 연구에서는 우리나라 수입구조의 위험도 분석을 통하여 공급리스크를 줄이고 안정적인 공급과 수요를 위한 방안을 제시하였다. 공급위험도를 감소시키기 위해 한 국가로부터의 수입 집중도를 낮춰야 하며, 가스공급안정성 지수 (gas supply security index, GSSI)가 낮은 국가의 수입비중을 낮추고 상대적으로 안정적인 국가인 러시아로부터 수입을 증가시켜야 한다. 또한, 수입국가의 수를 늘리거나 안정적 공급이 가능한 국가와의 관계 유지는 우리나라 수입가스의 공급안정성지표 (total gas supply security index, TGSSI)에 긍정적인 영향을 줄 것으로 분석되었다. Natural gas is globally emerging as an important energy source for environmental, political and regional reasons. In Korea, natural gas imported from oversea natural gas resources as a LNG, it is increased for an applications as a fuel and feedstock which replace the coal and nuclear energy. Because it is relied on the import market in Korea, it is very important to analyze the security for supply. Therefore, this study suggested a method for reducing supply risk and for providing stable supply and demand through risk analysis of Koreas import structure. In order to reduce the supply risk, the concentration of importing countries should be lowered and it is necessary to lower the proportion of countries with relatively low GSSI and increase the imports from Russia. Finally increasing the number of importing countries or maintaining friendly relations with countries where the supply is stable could give us the positive impact in terms of total GSSI.