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The first synthesis of well‐defined poly(methylene‐co‐1,1‐diphenylpropenenylene) (C1‐co‐C1'), equivalent to poly(ethylene‐co‐diphenylbutadiene) copolymers was accomplished by C1 copolymerization of novel diphenylpropenyl triphenyl arsonium ylides (Ph2AY) and dimethylsulfoxonium methylide (Me2SY) using B‐thexylborepane as initiator. All polymerization conditions, including feed ratio, temperature, and reaction time, were optimized. A series of photoluminescent poly(ethylene‐co‐diphenylbutadiene)s were synthesized at different feed ratios, opening a new synthetic horizon for poly(ethylene‐co‐disubstitutedbutadiene) copolymers. Notably, a new C1 segment, arising from a double bond rearrangement, was confirmed by NMR, resulting in an unprecedented two‐monomer three‐structure random terpolymer. An unexpected red‐shift phenomenon in the fluorescence spectra was observed with increasing the ratio of Ph2AY in the copolymer. This shift is attributed to the aggregation of diphenylbutadiene segment, similar to through‐space conjugation (TSC), likely induced by a decrease in the crystallinity of copolymers. Furthermore, another disubstituted allylic triphenyl arsonium ylides, (E)‐2‐phenylbutenyl triphenyl arsonium ylide (MePhAY) was also synthesized and investigated. These additional compounds expand the knowledge and the potential applications of such copolymerization techniques in advanced materials. [ABSTRACT FROM AUTHOR]

The first synthesis of well‐defined poly(methylene‐co‐1,1‐diphenylpropenenylene) (C1‐co‐C1'), equivalent to poly(ethylene‐co‐diphenylbutadiene) copolymers was accomplished by C1 copolymerization of novel diphenylpropenyl triphenyl arsonium ylides (Ph2AY) and dimethylsulfoxonium methylide (Me2SY) using B‐thexylborepane as initiator. All polymerization conditions, including feed ratio, temperature, and reaction time, were optimized. A series of photoluminescent poly(ethylene‐co‐diphenylbutadiene)s were synthesized at different feed ratios, opening a new synthetic horizon for poly(ethylene‐co‐disubstitutedbutadiene) copolymers. Notably, a new C1 segment, arising from a double bond rearrangement, was confirmed by NMR, resulting in an unprecedented two‐monomer three‐structure random terpolymer. An unexpected red‐shift phenomenon in the fluorescence spectra was observed with increasing the ratio of Ph2AY in the copolymer. This shift is attributed to the aggregation of diphenylbutadiene segment, similar to through‐space conjugation (TSC), likely induced by a decrease in the crystallinity of copolymers. Furthermore, another disubstituted allylic triphenyl arsonium ylides, (E)‐2‐phenylbutenyl triphenyl arsonium ylide (MePhAY) was also synthesized and investigated. These additional compounds expand the knowledge and the potential applications of such copolymerization techniques in advanced materials. [ABSTRACT FROM AUTHOR]

Clarification question generation is used mainly to solve the potential missing product information problem in e-commerce. However, the problem of not being able to better understand contextual semantic information has arisen when studying the diversity and specificity of clarification questions. This further leads to imprecise prediction of question keywords. With the aim of solving the current constraints, we propose the Transformer Encoder of Keyword Predictor Keyword-Conditioned Network (TEKPCNet). First, the transformer encoder has been proven to perform well in predicting external question keywords by encoding context. Then, the Text Convolutional Neural Network (TextCNN) and multilayer perceptron are combined to enhance the input of the encoder-decoder model. The diversity and specificity of the clarification question generation process should be further enhanced. Finally, the decoding process is completed by combining the attention mechanism. The generated clarification questions were evaluated in terms of two datasets using both automatic assessment and human evaluation. The experimental results show that the proposed model outperforms the other models. [ABSTRACT FROM AUTHOR]

We investigate the buckling and post-buckling properties of a hyperelastic half-space coated by two hyperelastic layers when the composite structure is subjected to a uniaxial compression. In the case of a half-space coated with a single layer, it is known that when the shear modulus μ f of the layer is larger than the shear modulus μ s of the half-space, a linear analysis predicts the existence of a critical stretch and wave number, whereas a weakly nonlinear analysis predicts the existence of a threshold value of the modulus ratio μ s / μ f ≈ 0. 57 below which the buckling is super-critical and above which the buckling is sub-critical. It is shown that when another layer is added, a larger variety of behaviour can be observed. For instance, buckling can occur at a preferred wavenumber super-critically even if both layers are softer than the half-space although the top layer would need to be harder than the bottom layer. When the shear modulus of the bottom layer lies in a certain interval, the super-critical to sub-critical transition can happen a number of times as the shear modulus of the top layer is increased gradually. Thus, an extra layer imparts more flexibility in producing wrinkling patterns with desired properties, and our weakly nonlinear analysis provides a road map on the parameter regimes where this can be achieved. [ABSTRACT FROM AUTHOR]

The effect of OZnAl-LDH and OZnFe-LDH on the catalytic dechlorination, thermal decomposition and smoke suppression of polyvinyl chloride (PVC) during pyrolysis processes was investigated and compared. The thermal degradation and combustion behavior of the PVC composites were investigated by thermogravimetric analysis and cone calorimetry, respectively. The results indicate that the addition of LDHs brought about the improved thermal stability and reduced heat release of PVC composites at high temperature. The smoke suppression properties of the composites are investigated by steady-state tube furnace. The results revealed that the toxic gases such as CO, CH4, NOx and N2O were inhibited by both two LDHs, but the OZnAl-LDH has better effect on the smoke suppression. Subsequently, the char layer was investigated by scanning electron microscopy–energy-dispersive spectrometry and Raman analysis. The results indicated that the LDHs can promote the dechlorination of PVC and form graphitized structures. Generally, OZnAl-LDH and OZnFe-LDH can be potential catalysts for waste disposal and improve the fire safety of PVC. [ABSTRACT FROM AUTHOR]

We report the first catalytic asymmetric approach to octahydroindolones and a divergent enantioselective synthesis of perhydroindole alkaloids, as exemplified by lycorine-type Amaryllidaceae alkaloids (+)-α-lycorane and (+)-lycorine, from a common intermediate by using a highly concise route. The assembly of octahydroindolones employs a catalytic enantioselective 1,4-conjugate addition of nitro dienynes, followed by a TsOH-catalyzed cascade synthesis of highly functionalized enones, and a diastereoselective intramolecular Michael addition. [ABSTRACT FROM AUTHOR]

Cerium-doped titanium dioxide (TiO2) with a hollow fiber structure was successfully prepared using ammonium ceric nitrate and tetrabutyltitanate as precursors and cotton fiber as the template. The effects of cerium (Ce)-doping on the crystallite sizes, crystal pattern, and optical property of the prepared catalysts were investigated by means of techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), BET surface area, and UV-vis diffuse absorption spectroscopy. SEM observation showed that the prepared TiO2 fibers possessed fibrous shape inherited from the cotton fiber and had a hollow structure. As confirmed by XRD and UV-vis diffuse absorption spectroscopy examinations, Ce-doping restrained the growth of grain size and extended the photoabsorption edge of TiO2 hollow fiber into the visible light region. The present photocatalyst showed higher photocatalytic reactivity in photodegradation of highly concentrated methylene blue (MB) solutions than pure TiO2 under UV and visible light, and the amount of Ce-doped significantly affected the catalytic property. In the experiment condition, the photocatalytic activity of 0.5 mol% Ce-doped TiO2 fiber was optimal of all the prepared samples. In addition, the possibility of cyclic usage of the photocatalyst was also confirmed. The material was easily removed by centrifugal separation. Therefore, using the template method and by doping with cerium, TiO2 may hopefully become a low-energy consuming, high activity and green environmentally friendly catalytic material. [ABSTRACT FROM AUTHOR]

The ZnO:N films are prepared by a wet chemical method. The temperature-dependent photoluminescence (PL) is used to investigate those ZnO: N films. Due to the introduction of nitrogen atoms into ZnO film, another phase appears in the ZnO film, which can release the stress and improve the film quality. As a result, a neutral donor-bound exciton (DX) emission peak is shown in low temperature PL spectrum. With the increasing temperature, the DX line gradually loses its intensity and shifts to 3.30 eV, which is consistent with the well-known conversion from bound exciton to free exciton at elevated temperatures. Then, due to the thermal quenching effect, the DX line vanishes in room temperature. In addition, no shift is shown in the location of visible band emission and only the intensity decreases with the increasing temperature. [ABSTRACT FROM AUTHOR]

A novel catalytic enantioselective synthesis of functionalized 1,3-enynes has been developed featuring the design and synthesis of conjugated nitro dienynes as a useful new class of Michael acceptors. Moreover, a simple, yet flexible catalytic cascade approach to functionalized enantioenriched acyclic α,β-enones and cyclic dienones has also been developed. [ABSTRACT FROM AUTHOR]