Catalytic Phosphination and Arsination

The catalytic, user-friendly phosphination and arsination of aryl halides and triflates by triphenylphosphine and triphenylarsine using palladium catalysts have provided a facile synthesis of functionalized aryl phosphines and arsines in neutral media. Modification of the cynaoarisne yielded optically active N, As ligands which will be screened in various asymmetric catalysis.     

Crash Diagnosis and Price Rebound Prediction in NYSE Composite Index Based on Visibility Graph and Time-Evolving Stock Correlation Network

This study proposes a framework to diagnose stock market crashes and predict the subsequent price rebounds. Based on the observation of anomalous changes in stock correlation networks during market crashes, we extend the log-periodic power-law model with a metric that is proposed to measure network anomalies. To calculate this metric, we design a prediction-guided anomaly detection algorithm based on the extreme value theory. Finally, we proposed a hybrid indicator to predict price rebounds of the stock index by combining the network anomaly metric and the visibility graph-based log-periodic power-law model. Experiments are conducted based on the New York Stock Exchange Composite Index from 4 January 1991 to 7 May 2021. It is shown that our proposed method outperforms the benchmark log-periodic power-law model on detecting the 12 major crashes and predicting the subsequent price rebounds by reducing the false alarm rate. This study sheds light on combining stock network analysis and financial time series modeling and highlights that anomalous changes of a stock network can be important criteria for detecting crashes and predicting recoveries of the stock market.     

Synthesis and X‐ray crystal structures of hypervalent arsenic compounds bearing arsenic‐iron bonds

A hypervalent arsorane with an As–Fe bond [ 6 : Rf₂As*FeCp(CO)₂ (Rf: o‐C₆H₄C(CF₃)₂O‐)] was synthesized by the reaction of the arsoranide anion ( 4‐Et ₄N: Rf₂As*^‐Et₄N⁺) with CpFe(CO)₂I ( 5 ) in the presence of AgBF₄. Diastereomeric arsoranes { 7a and 7b : Rf₂As*Fe*Cp(CO)(PPh₃)} were prepared by irradiation of 6 with a tungsten lamp in the presence of triphenylphosphine. X‐ray crystallographic analysis of 6 and 7a showed that the apical As–O bond lengths of these compounds are slightly longer than the equatorial As–C bonds. It is concluded that an electron‐donating group at the equatorial position elongates the apical E–O bond by electron donation to the apical oxygens. © 2000 John Wiley & Sons, Inc. Heteroatom Chem 11:42–47, 2000     

硝酸盐的大平反

Through three stories about nitrates, a storytelling technique is used to describe the main uses of nitrates today, including agricultural fertilizers, industrial explosives, and food preservatives. Nowadays, nitrate is suspected to be the main cause of carcinogenesis, but one coin has two sides; in fact, nitrates play an important role both in the ecological environment and in the human body. Therefore, the public can understand more about the applications of nitrates from this article. Through the accidental discovery of a rural couple in a wartime setting, this article describes the uses of nitrate in agriculture, antiseptic, immune systems and blood circulation system.     

Neural Network Structure Optimization by Simulated Annealing

A critical problem in large neural networks is over parameterization with a large number of weight parameters, which limits their use on edge devices due to prohibitive computational power and memory/storage requirements. To make neural networks more practical on edge devices and real-time industrial applications, they need to be compressed in advance. Since edge devices cannot train or access trained networks when internet resources are scarce, the preloading of smaller networks is essential. Various works in the literature have shown that the redundant branches can be pruned strategically in a fully connected network without sacrificing the performance significantly. However, majority of these methodologies need high computational resources to integrate weight training via the back-propagation algorithm during the process of network compression. In this work, we draw attention to the optimization of the network structure for preserving performance despite compression by pruning aggressively. The structure optimization is performed using the simulated annealing algorithm only, without utilizing back-propagation for branch weight training. Being a heuristic-based, non-convex optimization method, simulated annealing provides a globally near-optimal solution to this NP-hard problem for a given percentage of branch pruning. Our simulation results have shown that simulated annealing can significantly reduce the complexity of a fully connected network while maintaining the performance without the help of back-propagation.     

Quinoxaline-based conjugated polymers containing ruthenium(II) bipyridine metal complex

A series of novel quinoxaline-based conjugated polymers which contain a ruthenium(II) bipyridine complex were synthesized by the Suzuki coupling reactions. UV/VIS spectroscopy showed that the spectral features of the polymers are dependent on the amount of metal complex present. Results from excitation and emission spectroscopy suggest an energy transfer between the backbone and the metal complex. The polymers exhibit hole carrier mobilities of ≈ 10⁻⁵ cm² · V⁻¹ · s⁻¹, which is comparable to organic photoconductors.