The size and morphology of the active phase (metal or metal oxide) are critical for the performance of heterogeneous catalysts. Conventional approaches for catalyst synthesis involve the modi cation of pore size and structure, the use of ligands to anchor the metal during preparation or the use of nanostructured oxides with well-de ned facets to provide suitable sites for metal nucleation and growth. However, these approaches may not yield durable catalysts for high temperature applications, such as the treatment of unburnt methane from natural gas fueled engines. Here we demonstrate an approach that relies on the trapping of metal single atoms on the support surface, in thermally stable form, to modify the nature of deposited metal/metal oxide clusters. By anchoring Pt ions on the catalyst support we can tailor the morphology of the deposited phase. In particular, two-dimensional (2-D) rafts of Pt/PtO x on the engineered catalyst support are formed by this approach, as opposed to three-dimensional (3-D) metal oxide nanoparticles on conventional supports. Adopting this approach for the synthesis of bimetallic catalysts via addition of Pd to the atom-trapped catalyst support (Pt@CeO 2 ) we found that the resulting Pd/Pt@CeO 2 catalyst provides improved thermal stability and water tolerance during methane oxidation.We attribute the improved performance to the 2-D morphology of the Pd/PdO phase present on the atomtrapped catalyst support. The results show that modifying the support by trapping single atoms could provide an important addition to the toolkit of catalyst designers to engineer catalyst supports for controlling the nucleation and growth of metal and metal oxide clusters in heterogeneous catalysts. the metal salt precursor on an oxide support 1 , via the methods of deposition-precipitation or strong electrostatic adsorption (SEA) 2 . Using these approaches, it is possible to achieve atomic dispersion of the deposited metal on a number of catalyst supports [3][4][5][6] . The interaction between the metal salt precursor and the functional groups on the surface (hydroxyls) determines the surface concentration of the dispersed phase. The nature and morphology of the dispersed phase depends on the surface structure of the oxide support 7, 8 , which can be manipulated by using faceted oxides as supports, or by introducing ligands on the support 9 . By pre-calcining the support, the number of hydroxyls on the support can be changed, which allows some control over the metal deposition (Scheme 1a).However, once the catalyst is treated at high temperatures, the mobility of the deposited metal leads to formation of thermodynamically stable structures, where the in uence of the initial preparation steps is lost. Here we explore an alternate approach where we trap metal atoms on the support to modify the
Polymeric fibres with small radii (such as ≤125 nm) are delicate to handle and should be laid down on a solid substrate to obtain practical devices. However, placing these nanofibres on commonly used glass substrates prevents them from guiding light. In this study, we numerically and experimentally demonstrate that when the nanofibre is placed on a suitable dielectric multilayer, it supports a guided mode, a Bloch surface wave (BSW) confined in one dimension. The physical origin of this new mode is discussed in comparison with the typical two-dimensional BSW mode. Polymeric nanofibres are easily fabricated to contain fluorophores, which make the dielectric nanofibre and multilayer configuration suitable for developing a large range of new nanometric scale devices, such as processor–memory interconnections, devices with sensitivity to target analytes, incident polarization and multi-colour BSW modes.
This study aimed to investigate the liver protection effect of Schisandra chinensis (Turcz.) Baill. (SC) lignans and its combination with Rubus idaeus (RI) on chronic alcohol-induced mice. A low level of SC lignans (SL) was prepared from the clear juice of sarcocarp. Lignans were further extracted from the SC seeds and added to the SL to form high-level SC lignans (SH). Moreover, RI clear juice lyophilized powder was mixed with SL (SR), and the liver protection effects of SL, SH and SR were investigated. Male ICR mice were administered with the corresponding samples and gastrically infused with 50% alcohol (1 h later) once per day for 60 d. In the in vitro study, the characteristic lignans in the SC clear juice and the seed extract were analyzed by high performance liquid chromatography (HPLC). The total phenolic content (TPC) and antioxidant capability of SL, SH, and SR were determined. The results of the in vivo study showed that SC lignans exhibited a dose-dependent effect on the regulation of hepatic antioxidant status, serum transaminases levels, hyperlipidemia and hepatic fat deposition in mice. However, hepatic lesions were observed in the SH mice, which indicated a potential side effect caused by long-term consumption of SH under chronic alcohol administration. By contrast, SR exhibited a similar hepatoprotective effect as SH without any abnormality found in the histological analysis. After analysis with HPLC, Schizandrol A and Schizandrol B were identified in the SC clear juice, and two more kinds of lignans, Schisandrin A and Schisandrin B, were identified in the seed extracts. The SR sample had the highest TPC and exhibited the best antioxidant capability. In conclusion, RI strengthened the liver protection effect of SC lignans effectively and safely, which was probably achieved by enhancing the antioxidant status and the positive effect of their combination was possibly attributed to both lignans and polyphenols. This study demonstrated that the combination of low-level SC lignans and RI might be used as a potential safe formula for beverage development to alleviate the adverse effects of long-term alcohol consumption.
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