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The effects of transition metal in Sn-based pyrochlores on the methane catalytic combustion 总被引:1,自引:0,他引:1
Zheng JIANG Jixin SU Yun HAN Farhan ALSHAHRANI Zhengping HAO Tiancun XIAO 《自然科学进展(英文版)》2005,15(13):134-138
Lanthanum stannate pyrochlores, La2Sn2O7 and La2SnMO7 (M=Mn, Fe, Co, Ni, Cu), were successfully prepared by citric acid method and confirmed by XRD. TG and TPR characterizations showed that the introduction of transitional metals resulted in significant impacts on the structures and redox performances of prochlores. All the selected transitional metals could significantly improve their methane catalytic combustion performance. Among the doped pyrochlores, La2SnCoO7 pyrochlore possessed optimum activities at low temperatures, and Fe?doped pyrochlore showed highest reactivity for high temperature combustion and was proved to be promising materials for high temperature catalytic combustion. The reactivity differences of La2SnMO7 were reasonably attributed to the strong interactions between Sn and transitional metal. 相似文献
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Carbon materials prepared using different methods were characterized by XRD, Laser Raman and BET (Brunauer Emmett and Teller) methods. Adsorption removal of dibenzothiophene (DBT) from octane solution was performed on these carbon materials at room temperature. The adsorption was carried out in a liquid phase at room temperature. The effect of carbon surface chemistry on DBT adsorption activity was also studied. Carbon materials’ DBT adsorption capacities show a strong dependence on surface areas, pore size distributions and micropore volumes, and the introduction of metal species enhances their adsorption capacities somehow. However, there is a limit to the amount of metal species loaded because overloading metal species would block the pores, which leads to the decrease of adsorption capacities of the activated carbon. 相似文献
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Christina Ulm Mona Saffarzadeh Poornima Mahavadi Sandra Müller Gerlinde Prem Farhan Saboor Peter Simon Ralf Middendorff Hildegard Geyer Ingrid Henneke Nils Bayer Susanne Rinné Thomas Lütteke Eva Böttcher-Friebertshäuser Rita Gerardy-Schahn David Schwarzer Martina Mühlenhoff Klaus T. Preissner Andreas Günther Rudolf Geyer Sebastian P. Galuska 《Cellular and molecular life sciences : CMLS》2013,70(19):3695-3708
Posttranslational modification of the neural cell adhesion molecule (NCAM) by polysialic acid (polySia) is well studied in the nervous system and described as a dynamic modulator of plastic processes like precursor cell migration, axon fasciculation, and synaptic plasticity. Here, we describe a novel function of polysialylated NCAM (polySia-NCAM) in innate immunity of the lung. In mature lung tissue of healthy donors, polySia was exclusively attached to the transmembrane isoform NCAM-140 and located to intracellular compartments of epithelial cells. In patients with chronic obstructive pulmonary disease, however, increased polySia levels and processing of the NCAM carrier were observed. Processing of polysialylated NCAM was reproduced in a mouse model by bleomycin administration leading to an activation of the inflammasome and secretion of interleukin (IL)-1β. As shown in a cell culture model, polySia-NCAM-140 was kept in the late trans-Golgi apparatus of lung epithelial cells and stimulation by IL-1β or lipopolysaccharide induced metalloprotease-mediated ectodomain shedding, resulting in the secretion of soluble polySia-NCAM. Interestingly, polySia chains of secreted NCAM neutralized the cytotoxic activity of extracellular histones as well as DNA/histone-network-containing “neutrophil extracellular traps”, which are formed during invasion of microorganisms. Thus, shedding of polySia-NCAM by lung epithelial cells may provide a host-protective mechanism to reduce tissue damage during inflammatory processes. 相似文献
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