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RISS 인기검색어
- 검색키워드
- 저자 : Risch, Harvey (검색결과 4 건)
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Park, Joohyuk,Risch, Marcel,Nam, Gyutae,Park, Minjoon,Shin, Tae Joo,Park, Suhyeon,Kim, Min Gyu,Shao-Horn, Yang,Cho, Jaephil Royal Society of Chemistry 2017 ENERGY AND ENVIRONMENTAL SCIENCE Vol.10 No.1
<P>Oxygen reduction reaction (ORR) or oxygen evolution reaction (OER) electrocatalysts including carbon-, non-precious metal-, metal alloy-, metal oxide-, and carbide/nitride-based materials are of great importance for energy conversion and storage technologies. Among them, metal oxides (<I>e.g.</I>, perovskite and pyrochlore) are known to be promising candidates as electrocatalysts. Nevertheless, the intrinsic catalytic activities of pyrochlore oxides are still poorly understood because of the formation of undesirable phases derived from the synthesis processes. Herein, we present highly pure single crystalline pyrochlore nanoparticles with metallic conduction (Pb2Ru2O6.5) as an efficient bi-functional oxygen electrocatalyst. Notably, it has been experimentally shown that the covalency of Ru-O bonds affects the ORR and OER activities by comparing the X-ray absorption near edge structure (XANES) spectra of the metallic Pb2Ru2O6.5and insulating Sm2Ru2O7for the first time. Moreover, we followed the interatomic distance changes of Ru-O bonds using<I>in situ</I>X-ray absorption spectroscopy (XAS) to investigate the structural stabilities of the pyrochlore catalysts during electrocatalysis. The highly efficient metallic Pb2Ru2O6.5exhibited outstanding bi-functional catalytic activities and stabilities for both ORR and OER in aqueous Zn-air batteries.</P>
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Optimizing nanoparticle perovskite for bifunctional oxygen electrocatalysis
Jung, Jae-Il,Risch, Marcel,Park, Seungkyu,Kim, Min Gyu,Nam, Gyutae,Jeong, Hu-Young,Shao-Horn, Yang,Cho, Jaephil The Royal Society of Chemistry 2016 ENERGY AND ENVIRONMENTAL SCIENCE Vol.9 No.1
<P>Highly efficient bifunctional oxygen electrocatalysts are indispensable for the development of highly efficient regenerative fuel cells and rechargeable metal-air batteries, which could power future electric vehicles. Although perovskite oxides are known to have high intrinsic activity, large particle sizes rendered from traditional synthesis routes limit their practical use due to low mass activity. We report the synthesis of nano-sized perovskite particles with a nominal composition of La-x(Ba0.5Sr0.5)(1-x)Co0.8Fe0.2O3-delta (BSCF), where lanthanum concentration and calcination temperature were controlled to influence oxide defect chemistry and particle growth. This approach produced bifunctional perovskite electrocatalysts similar to 50 nm in size with supreme activity and stability for both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). The electrocatalysts preferentially reduced oxygen to water (o5% peroxide yield), exhibited more than 20 times higher gravimetric activity (A g(-1)) than IrO2 in OER half-cell tests (0.1 M KOH), and surpassed the charge/discharge performance of Pt/C (20 wt%) in zinc-air full cell tests (6 M KOH). Our work provides a general strategy for designing perovskite oxides as inexpensive, stable and highly active bifunctional electrocatalysts for future electrochemical energy storage and conversion devices.</P>
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Prevalence and risk factors of hepatits C virus infection among Koreans in rural area of Korea
Shin, Hai-Rim,Kim, Joon-Youn,Ohno, Tomoyoshi,Cao, Kun,Mizokami, Masashi,Risch, Harvey,Kim, SooRyang 동아대학교 산업의학연구소 2000 산업의학연구소 논총 Vol.- No.5
In a Korean rural area with a high incidence of liver cancer, a molecular epidemiological study was conducted to estimate the prevalence of hepatitis C virus (HCV) infection and to determine the distribution of HCV genotype and transmission routes of HCV infection, The study population is those who volunteered to participate in a health survey in 1993 and were over 10 years of age. Those who were anti-HCV-positive and 20 of their spouses were re-examined in 1995 and tested for HCV genotype. A phylogenetic tree was constructed after sequencing analysis of core and envelope regions from the subjects with genotype 2a without a blood transfusion history. The age- and sex-standardized prevalence of anti-HCV was 5.52%. In a multivariate analysis, transfusion history was not associated with anti-HCV-pos-itivity, but a history of acupuncture (adjusted odds ratio = 2.2, 95% confidence interval = 1.0, 4.7) and a history of surgical operation (adjusted odds ratio = 2.0, 95%, confidence interval = 1.0, 4.1) were associated. The prevalence of HCV genotype 2a was the highest, and genotype 1b was less frequent. The phylogenetic tree showed strong homology among our samples with Japanese HCV strains. The present study suggests that there is a highly endemic area of HCV infection in Korea and that this endemicity is probably associated with a parenteral source of HCV infection other than blood transfusion. The study also suggests that some of the HCV infection was spread through non-sterilized or non-disposable acupuncture needles in this HCV endemic
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Arab, K.,Park, Y.,Lindroth, Anders M.,Schafer, A.,Oakes, C.,Weichenhan, D.,Lukanova, A.,Lundin, E.,Risch, A.,Meister, M.,Dienemann, H.,Dyckhoff, G.,Herold-Mende, C.,Grummt, I.,Niehrs, C.,Plass, C. Cell Press 2014 Molecular cell Vol.55 No.4
DNA methylation is a dynamic and reversible process that governs gene expression during development and disease. Several examples of active DNA demethylation have been documented, involving genome-wide and gene-specific DNA demethylation. How demethylating enzymes are targeted to specific genomic loci remains largely unknown. We show that an antisense lncRNA, termed TARID (for TCF21 antisense RNA inducing demethylation), activates TCF21 expression by inducing promoter demethylation. TARID interacts with both the TCF21 promoter and GADD45A (growth arrest and DNA-damage-inducible, alpha), a regulator of DNA demethylation. GADD45A in turn recruits thymine-DNA glycosylase for base excision repair-mediated demethylation involving oxidation of 5-methylcytosine to 5-hydroxymethylcytosine in the TCF21 promoter by ten-eleven translocation methylcytosine dioxygenase proteins. The results reveal a function of lncRNAs, serving as a genomic address label for GADD45A-mediated demethylation of specific target genes.
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