In this talk, I will discuss our recent efforts to develop purely dielectric metamaterials possessing low absorption loss at optical frequencies. I will discuss implementations ranging from wavefront control to high Q...
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ISBN:
(纸本)9781467371100
In this talk, I will discuss our recent efforts to develop purely dielectric metamaterials possessing low absorption loss at optical frequencies. I will discuss implementations ranging from wavefront control to high Q-factor resonances.
Proton‐coupled electron‐transfer oxidation of a Ru II −OH 2 complex, having an N‐heterocyclic carbene ligand, gives a Ru III −O . species, which has an electronically equivalent structure of the Ru IV =O species, i...
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Proton‐coupled electron‐transfer oxidation of a Ru II −OH 2 complex, having an N‐heterocyclic carbene ligand, gives a Ru III −O . species, which has an electronically equivalent structure of the Ru IV =O species, in an acidic aqueous solution. The Ru III −O . complex was characterized by spectroscopic methods and DFT calculations. The oxidation state of the Ru center was shown to be close to +3; the Ru−O bond showed a lower‐energy Raman scattering at 732 cm −1 and the Ru−O bond length was estimated to be 1.77(1) Å. The Ru III −O . complex exhibits high reactivity in substrate oxidation under catalytic conditions; particularly, benzaldehyde and the derivatives are oxidized to the corresponding benzoic acid through C−H abstraction from the formyl group by the Ru III −O . complex bearing a strong radical character as the active species.
Packings of hard polyhedra have been studied for centuries due to their mathematical aesthetic and more recently for their applications in fields such as nanoscience, granular and colloidal matter, and biology. In all...
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Packings of hard polyhedra have been studied for centuries due to their mathematical aesthetic and more recently for their applications in fields such as nanoscience, granular and colloidal matter, and biology. In all these fields, particle shape is important for structure and properties, especially upon crowding. Here, we explore packing as a function of shape. By combining simulations and analytic calculations, we study three two-parameter families of hard polyhedra and report an extensive and systematic analysis of the densest known packings of more than 55 000 convex shapes. The three families have the symmetries of triangle groups (icosahedral, octahedral, tetrahedral) and interpolate between various symmetric solids (Platonic, Archimedean, Catalan). We find optimal (maximum) packing-density surfaces that reveal unexpected richness and complexity, containing as many as 132 different structures within a single family. Our results demonstrate the importance of thinking about shape not as a static property of an object, in the context of packings, but rather as but one point in a higher-dimensional shape space whose neighbors in that space may have identical or markedly different packings. Finally, we present and interpret our packing results in a consistent and generally applicable way by proposing a method to distinguish regions of packings and classify types of transitions between them.
Single‐layered two‐dimensional (2D) ultrathin mesoporous polymer/carbon films are grown by self‐assembly of monomicelles at the interfaces of various substrates, which is a general and common modification strategy....
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Single‐layered two‐dimensional (2D) ultrathin mesoporous polymer/carbon films are grown by self‐assembly of monomicelles at the interfaces of various substrates, which is a general and common modification strategy. These unconventional 2D mesoporous films possess only a single layer of mesopores, while the size of the thin films can grow up to inch size in the plane. Free‐standing transparent mesoporous carbon ultrathin films, together with the ordered mesoporous structure on the substrates of different compositions (e.g. metal oxides, carbon) and morphologies (e.g. nanocubes, nanodiscs, flexible and patterned substrates) have been obtained. This strategy not only affords controllable hierarchical porous nanostructures, but also appends the easily modified and multifunctional properties of carbon to the primary substrate. By using this method, we have fabricated Fe 2 O 3 –mesoporous carbon photoelectrochemical biosensors, which show excellent sensitivity and selectivity for glutathione.
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