Thermally stable mesoporous core-shell structured titania microspheres with well-defined hollow interiors were directly prepared by a novel hydrothermal precipitation of TiCl4 in the presence of urea and ammonium sulfate.
Zeolite's mesoporous cousins: High-surface-area single-crystal-like anatase-TiO2 was synthesized by a simple solution-growth method. This method produces a controllable mesoporous network and preferential exposure of the highly active (001) planes (see TEM) and is readily extendable to the synthesis of other mesoporous single crystals for application in, for example, catalysis and energy storage. Detailed facts of importance to specialist readers are published as "Supporting Information". Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.
We study the fundamental problem of reflection and refraction of a surface polariton as it strikes the interface between two waveguide structures. By making the two waveguide structures match to each other, coupling of surface polaritons to radiating modes is cancelled, and the reflected and transmitted waves consist of only surface modes. The reflection and transmission coefficients are calculated, and negative refraction of surface polaritons is demonstrated. Finite-difference time-domain numerical simulations are also performed to verify the analytical results. As one of the applications of the matched waveguide structure, a square corner reflector for phase-retardation-free reflection of surface polaritons is proposed.
Reduction of carbonyl compounds with a TiO2-supported Au catalyst (Au/TiO2) was performed under transfer hydrogenation conditions using i-PrOH to afford the corresponding alcohols in 31-99% conversion with 86-100% selectivities. In the reduction of acetophenone, the catalyst was recovered by simple filtration and reused four times without significant loss of catalytic activity (98.5% conversion, 100% selectivity for 4th reuse run). When 4-nitroacetophenone was used as a substrate, hydrogenation of the nitro group occurred to give 4-aminoacetophenone in 99% yield.
Neural network capability in symbolic computation has emerged in much recent work. However, symbolic computation is always treated as an end-to-end blackbox prediction task, where human-like symbolic deductive logic is missing. In this paper, we argue that any complex symbolic computation can be broken down to a sequence of finite Fundamental Computation Transformations (FCT), which are grounded as certain mathematical expression computation transformations. The entire computation sequence represents a full human understandable symbolic deduction process. Instead of studying on different end-to-end neural network applications, this paper focuses on approximating FCT which further build up symbolic deductive logic. To better mimic symbolic computations with math expression transformations, we propose a novel tree representation learning architecture GATE (Graph Aggregation Transformer Encoder) for math expressions. We generate a large-scale math expression transformation dataset for training purpose and collect a real-world dataset for validation. Experiments demonstrate the feasibility of producing step-by-step human-like symbolic deduction sequences with the proposed approach, which outperforms other neural network approaches and heuristic approaches.
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