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21.
In this paper, the polyhedral Pt nanoparticles under control were prepared by polyol method using AgNO3 and poly(vinylpyrrolidone) (PVP) in the reduction of H2PtCl6 with ethylene glycol (EG). Transmission electron microscopy (TEM) and high resolution (HR) TEM measurements were used to investigate their characterization. In the case of the previous removal of PVP by washing and heating at 300°C, the specific morphologies of polyhedral Pt nanoparticles were still observed. However, the removal of PVP only by heat treatment at 300°C without washing causes the significant variation of their morphology. The large Pt particles were observed in the self-aggregation and assembly of the as-prepared polyhedral Pt nanoparticles. The pure Pt nanoparticles by washing and heat treatment showed the electrocatalytic property better than PVP-Pt nanoparticles by heat treatment due to the incomplete removal of PVP and by-products from AgNO3. Therefore, the removal modes of PVP without changing their characterization are required to obtain the good catalytic performance.  相似文献   
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For a graph G and a set \({\mathcal{F}}\) of connected graphs, G is said be \({\mathcal{F}}\) -free if G does not contain any member of \({\mathcal{F}}\) as an induced subgraph. We let \({\mathcal{G} _{3}(\mathcal{F})}\) denote the set of all 3-connected \({\mathcal{F}}\) -free graphs. This paper is concerned with sets \({\mathcal{F}}\) of connected graphs such that \({\mathcal{F}}\) contains no star, \({|\mathcal{F}|=3}\) and \({\mathcal{G}_{3}(\mathcal{F})}\) is finite. Among other results, we show that for a connected graph T( ≠ K 1) which is not a star, \({\mathcal{G}_{3}(\{K_{4},K_{2,2},T\})}\) is finite if and only if T is a path of order at most 6.  相似文献   
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We construct, for any symplectic, unitary or special orthogonal group over a locally compact nonarchimedean local field of odd residual characteristic, a type for each Bernstein component of the category of smooth representations, using Bushnell–Kutzko’s theory of covers. Moreover, for a component corresponding to a cuspidal representation of a maximal Levi subgroup, we prove that the Hecke algebra is either abelian, or a generic Hecke algebra on an infinite dihedral group, with parameters which are, at least in principle, computable via results of Lusztig. In an appendix, we make a correction to the proof of a result of the second author: that every irreducible cuspidal representation of a classical group as considered here is irreducibly compactly-induced from a type.  相似文献   
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A chiral tripodal ligand was demonstrated to form a series of lanthanide complexes exhibiting multiple anion-sensing profiles, which incorporated a fluorescent quinoline and a stereo-controlled substituent in a tetradentate skeleton. This mainly gave 1:2 (lanthanide cation/ligand) complexes with lanthanide triflates but 1:1 complexes with lanthanide nitrates. Since addition of external guest anion dynamically changed the preferred stoichiometry, the chiral lanthanide complexes exhibited anion-responsive fluorescence, luminescence, and circular dichroism spectral characteristics as multiple anion-sensing probes.  相似文献   
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Although the supply of 12-oxo-PDA (1) and OPC-8:0 (2), the metabolites in the linolenic acid cascade leading to epi-jasmonic acid, is in demand for biological investigations, the previous syntheses of these metabolites suffer from low efficiency. Recently, we established a reaction to install an alkyl group onto the ring of cyclopentene monoacetate 4 by using a reagent system consisting of RMgCl (3 equiv) and CuCN (cat). The reaction was applied to ClMg(CH2)8OTBDPS (11) with modification by which the quantity of 11 could be reduced to 2 equiv without decreasing efficiency. The product 12 obtained in 88% yield with 92% regioselectivity was successfully transformed into the key iodo-lactone 17 in good yield, from which 12-oxo-PDA (1) and OPC-8:0 (2) were synthesized as described in Schemes 3 and 5 through construction of the cis side chain by Wittig reaction. Note that the Wittig reaction proceeded with high cis selectivity of >95%, which is higher than in similar cases reported previously. Synthesis of the 13-isomers of 1 and 2 was also accomplished. With these compounds in hand, the epimerization speed of 1 and 2 was investigated to rule out overestimation of the finding in the literature that 1 and 2 change to the 13-epimers easily. Instead, we observed that the compounds are quite stable at room temperature for an extended period of days under slightly acidic and neutral conditions.  相似文献   
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Climacostol (1), a defense toxin of the heterotrich ciliate Climacostomum virens was established as 5-(Z)-non-2-enyl-benzene-1,3-diol. The structure was rigorously confirmed by the total synthesis. The two congeners of climacostol contained in this ciliate were determined as 5-(Z,Z)-undeca-2,5-dienyl-benzene-1,3-diol (2) and 5-(Z,Z,Z)-undeca-2,5,8-trienyl-benzene-1,3-diol (3).  相似文献   
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