关于Fejer点上的一种复有理型插值的一致逼近阶

设D是一个Jordan,Г为其边界，并设Г满足Aльпер条件。本文得到了一种基于Fejer点的有理型插值算子对于f(z)∈C（Г）的一致逼近阶。     

Some Properties of Solutions to the Novikov Equation with Weak Dissipation Terms

In this paper, we investigate the Novikov equation with weak dissipation terms. First, we give the local well-posedness and the blow-up scenario. Then, we discuss the global existence of the solutions under certain conditions. After that, on condition that the compactly supported initial data keeps its sign, we prove the infinite propagation speed of our solutions, and establish the large time behavior. Finally, we also elaborate the persistence property of our solutions in weighted Sobolev space.     

Catalytic Platinum Nanoparticles Decorated with Subnanometer Molybdenum Clusters for Biomass Processing

The development of improved technologies for biomass processing into transportation fuels and industrial chemicals is hindered due to a lack of efficient catalysts for selective oxygen removal. Here we report that platinum nanoparticles decorated with subnanometer molybdenum clusters can efficiently catalyze hydrodeoxygenation of acetic acid, which serves as a model biomass compound. In contrast with monometallic Mo catalysts that are inactive and monometallic Pt catalysts that have low activities and selectivities, bimetallic Pt–Mo catalysts exhibit synergistic effects with high activities and selectivities. The maximum activity occurs at a Pt to Mo molar ratio of three. Although Mo atoms themselves are catalytically inactive, they serve as preferential binding anchors for oxygen atoms while a catalytic transformation proceeds on neighboring surface Pt atoms. Beyond biomass processing, Pt–Mo nanoparticles are promising catalysts for a wide variety of reactions that require a transformation of molecules with an oxygen atom and, more broadly, in other fields of science and technology that require tuning of surface–oxygen interactions.     

Charge redistribution and a shortening of the Fe—As bond at the quantum critical point of SmO1–xFxFeAs

Many researchers have pointed out that there is a quantum critical point (QCP) in the F‐doped SmOFeAs system. In this paper, the electronic structure and local structure of the superconductive FeAs layer in SmO_1–xF_xFeAs as a function of the F‐doping concentration have been investigated using Fe and As K‐edge X‐ray absorption spectroscopy. Experiments performed on the X‐ray absorption near‐edge structure showed that in the vicinity of the QCP the intensity of the pre‐edge feature at the Fe‐edge decreases continuously, while there is a striking rise of the shoulder‐peak at the As edge, suggesting the occurrence of charge redistribution near the QCP. Further analysis on the As K‐edge extended X‐ray absorption fine structure demonstrated that the charge redistribution originates mostly from a shortening of the Fe—As bond at the QCP. An evident relationship between the mysterious QCP and the fundamental Fe—As bond was established, providing new insights on the interplay between QCP, charge dynamics and the local structural Fe—As bond in Fe‐based superconductors.     

Facile Synthesis of Sub-Nanometric Copper Clusters by Double Confinement Enables Selective Reduction of Carbon Dioxide to Methane

Previous density-functional theory (DFT) calculations show that sub-nanometric Cu clusters (i.e., 13 atoms) favorably generate CH₄ from the CO₂ reduction reaction (CO₂RR), but experimental evidence is lacking. Herein, a facile impregnation-calcination route towards Cu clusters, having a diameter of about 1.0 nm with about 10 atoms, was developed by double confinement of carbon defects and micropores. These Cu clusters enable high selectivity for the CO₂RR with a maximum Faraday efficiency of 81.7 % for CH₄. Calculations and experimental results show that the Cu clusters enhance the adsorption of *H and *CO intermediates, thus promoting generation of CH₄ rather than H₂ and CO. The strong interactions between the Cu clusters and defective carbon optimize the electronic structure of the Cu clusters for selectivity and stability towards generation of CH₄. Provided here is the first experimental evidence that sub-nanometric Cu clusters facilitate the production of CH₄ from the CO₂RR.     

二维磁性纳米材料的可控合成及磁性调控

自旋电子学的研究重点在于同时利用电子的电荷和自旋两个自由度对信息进行处理和存储,其具有运行速度快、存储密度高和能耗低等优势。毫无疑问,发展二维磁性纳米材料的可控合成方法及磁性调控策略,对于新型自旋电子学器件的构筑具有重要的科学意义和应用价值。然而,目前得到的二维磁性纳米材料的种类十分有限,而且合成方法及磁性调控手段相对单一,极大地限制了该领域的发展。本文首先根据磁性的来源,对二维磁性纳米材料进行了分类,介绍了诱导产生的磁性和具有本征磁性的二维纳米材料,然后详细地归纳了二维磁性纳米材料常见的合成方法,如机械剥离法、电化学剥离法、化学气相沉积法以及液相合成方法等。此外,着重总结了二维材料磁性的主要调控手段,最后展望了该领域遇到的瓶颈、未来的研究重点及应用前景。     

Designing Sub‐2 nm Organosilica Nanohybrids for Far‐Field Super‐Resolution Imaging

Stimulated emission depletion (STED) microscopy enables ultrastructural imaging of biological samples with high spatiotemporal resolution. STED nanoprobes based on fluorescent organosilica nanohybrids featuring sub‐2 nm size and near‐unity quantum yield are presented. The spin–orbit coupling (SOC) of heavy‐atom‐rich organic fluorophores is mitigated through a silane‐molecule‐mediated condensation/dehalogenation process, resulting in bright fluorescent organosilica nanohybrids with multiple emitters in one hybrid nanodot. When harnessed as STED nanoprobes, these fluorescent nanohybrids show intense photoluminescence, high biocompatibility, and long‐term photostability. Taking advantage of the low‐power excitation (0.5 μW), prolonged singlet‐state lifetime, and negligible depletion‐induced re‐excitation, these STED nanohybrids present high depletion efficiency (>96 %), extremely low saturation intensity (0.54 mW, ca. 0.188 MW cm^?2), and ultra‐high lateral resolution (ca. λ_em/28).     

Speciation of zinc in secondary fly ashes of municipal solid waste at high temperatures

The evaporation aerosols produced during the vitrification process of municipal solid waste incinerators (MSWI) fly ash represent a potential environmental risk owing to their high content of heavy metals. In this research, high‐temperature heating processes were carried out on fly ashes collected from bag houses in a Chinese MSWI plant and the secondary fly ashes (SFA) were separately collected at three high temperatures (1273 K, 1423 K and 1523 K) below the melting range. Elemental analysis showed that high contents of both zinc and chlorine were present in these SFA samples and, according to the standard of the heavy metals industrial grade of ore, SFAs can be re‐used as metallurgical raw materials or rich ore. Moreover, as shown by XAS analysis and for different high temperatures, zinc environments in the three SFA samples were characterized by the same local structure of the zinc chloride. As a consequence, a zinc recycling procedure can be easily designed based on the configuration information.     

3D visualization of the microstructure of Quedius beesoni Cameron using micro-CT

The investigation of the internal morphology of insects is usually performed using classical microtomy yielding optical micrographs of stained thin sections. The achievement of high-quality cross sections for microtomy is time-consuming and the risk of damaging sections is unavoidable. Moreover, the approach is impractical, in particular when quick acquisition of 3D structural information is required. Recently, X-ray computed microtomography (micro-CT) with a high spatial resolution was considered as a potential tool for the morphological classification of insects. We used micro-CT to investigate Quedius beesoni Cameron at the cellular length scale. This method provides a new powerful and nondestructive approach to obtain 3D structural information on the biological organization of insects. The preliminary images presented in this contribution clearly reveal the endoskeleton and the muscles of the head and the thorax with a full 3D structure. We also reconstructed the 3D structure of the brain of Quedius beesoni Cameron, and this is the first reconstruction in Staphylinidae, which will be a great advancement for morphological and phylogenic research. We claim that both the spatial resolution and the contrast characteristic of micro-CT imaging may fulfill the requirements necessary for zoological insect morphology and phylogeny, in particular, when a classification of a rare and unique insect specimen is required.