We herein report α-arylsulfonyloxyacrylates as a kind of useful and attractive O-centered electrophiles for Suzuki cross-coupling reactions. A range of α-(hetero)aryl substituted acrylates has been prepared via the palladium-catalysed C-C cross-coupling reactions between potassium (hetero)aryltrifluoroborates and α-arylsulfonyloxyacrylates. Moreover, α-arylsulfonyloxyacrylate could also react with B-alkyl-9-BBN to produce α-alkyl substituted acrylates. The synthetic application of this new method was demonstrated by the preparation of the intermediate for synthesis of retinoid X receptors-selective retinoids. These Suzuki reaction-based protocols feature broad substrate scope, generality, and mild reaction conditions.
With the increasing popularity of location-aware Internet-of-Vehicle services, the next-Point-of-Interest (POI) recommendation has gained significant research interest, predicting where drivers will go next from their sequential movements. Many researchers have focused on this problem and proposed solutions. Machine learning-based methods (matrix factorization, Markov chain, and factorizing personalized Markov chain) focus on a POI sequential transition. However, they do not recommend the user’s position for the next few hours. Neural network-based methods can model user mobility behavior by learning the representations of the sequence data in the high-dimensional space. However, they just consider the influence from the spatiotemporal dimension and ignore many important influences, such as duration time at a POI (Point of Interest) and the semantic tags of the POIs. In this paper, we propose a novel method called multi-dimension spatial–temporal recurrent neural networks (MST-RNN), which extends the ST-RNN and exploits the duration time dimension and semantic tag dimension of POIs in each layer of neural networks. Experiments on real-world vehicle movement data show that the proposed MST-RNN is effective and clearly outperforms the state-of-the-art methods.
The differences of nonlinear absorption coefficient β are theoretically and numerically studied under both of the beam sections of plain and Gaussian distribution. The formula of energy transmission is derived on the base of temporal profile of Gaussian pulse beam. According to the formula, the absolute and relative differences of β are also estimated in compare with plain beam and the pulse beam that is rectangular in time but Gaussian in space. The relative differences turn out theoretically to be about 183% and 41.4% respectively. The further numerical simulation shows that these values are only the least differences. The existed differences mean that, according to the temporal influence of pulse, one should get a lager value of β in past performed routine experiments of nonlinear energy transmission. Our result suggests that, by taking temporal profile of a pulse beam into account, one can obtain more exact value of two-photon absorption cross section of the molecule experimentally.
Using the method of emergy analysis,we analyze the input and output of agro-ecological economic system,and select five indicators(net emergy yield ratio,emergy investment ratio,environmental loading ratio,emergy sustainability index,and dominance of emergy yield system) for assessment.The results show that the emergy input-output in Wu'an City is in general on the rise;the emergy investment ratio rises constantly,but the net emergy yield ratio decreases,and the comparative advantage in the prices of agricultural products is gradually lost.At the same time,with increase in the non-renewable industrial support emergy,the environmental pressures are also mounting.In the future agricultural development,it is necessary to pay more attention to the coordination between agricultural development and ecological environment,achieving sustainable development of agriculture.
Based on the analytical solutions of the wave equations in the elliptical-cylindrical coordinate system, the propagation characteristics of hollow elliptical waveguide for THz Radiation are investigated, and then the mode characteristic equations are also given. Our results show that the mode characteristic equations of a circular waveguide can be treated as a special case of an elliptic waveguide. The propagation characteristics are numerically simulated depending on the refractive index of dielectrics films and the eccentricity of the elliptic waveguide. The cutoff wavelengths of guided modes in the elliptic waveguide are also presented.
