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In this paper, a highly sensitive method for sulfur ion (S2−) detection was developed based on a four‐color fluorescence probe constructed from copper‐containing metal–organic framework (CuBDC) and four dye‐labeled single‐strand DNA (ssDNA). In the absence of S2−, dye‐labeled ssDNA can be adsorbed on the surface of CuBDC, and the dyes are close to copper ion on the CuBDC surface, their fluorescence is quenched by copper ion, and their fluorescence signals are weak. In the presence of S2− in the system, S2− reacts with copper ion in CuBDC to form CuS, which has a more stable structure than complex CuBDC, resulting in the decomposition of CuBDC. In this case, dye‐labeled ssDNA are detached from the CuBDC surface and dissolved in the solution, and the fluorescence of the dyes is restored. Under the optimized conditions, there is a good linear relationship between the total fluorescence intensity of four dyes and the concentration of S2− in the range of 2 × 10−9 to 5 × 10−8 mol/L; the detection limit is 2.2 × 10−10 mol/L. The method has a good selectivity and accuracy, and it can be applied to the analysis and detection of S2− in actual water samples. [ABSTRACT FROM AUTHOR]

Perovskite oxides and organic–inorganic halide perovskite materials, with numerous fascinating features, have been subjected to extensive studies. Most of the properties of perovskite materials are dependence on their ferroelectricity that denoted by remanent polarization (Pr). Thus, the increase of Pr in perovskite films is mainly an effort in material physics. At present, commonplace improvement schemes, i.e., controlling material crystallinity, and post‐annealing by using a high‐temperature process, are normally used. However, a simpler and temporal strategy for Pr improvement is always unavailable to perovskite material researchers. In this study, an organic coating layer, low‐temperature, and vacuum‐free strategy is proposed to improve the Pr, directly increasing the Pr from 36 to 56 µC cm−2. Further study finds that the increased Pr originates from the suppression of the oxygen defects and Ti defects. This organic coating layer strategy for passivating the defects may open a new way for the preparation of higher‐performance and cost‐effective perovskite products, further improving its prospective for application in the electron devices field. [ABSTRACT FROM AUTHOR]

Recently, actor-critic architectures such as deep deterministic policy gradient (DDPG) are able to understand higher-level concepts for searching rich reward, and generate complex actions in continuous action space, and widely used in practical applications. However, when action space is limited and has dynamic hard margins, training DDPG can be problematic and inefficiency. Since real-world actuators always have margins and interferences, after initialization, the actor network is likely to be stuck at a local optimal point on action space margin: actor gradient orients to the outside of action space but actuators stop at the margin. If the hard margins are complex, dynamic and unknown to the DDPG agent, it is unable to use penalty functions to recover from local optimum. If we enlarge the random process for local exploration, the training could be in potential risk of failure. Therefore, simply relying on gradient of critic network to train the actor network is not a robust method in real environment. To solve this problem, in this paper we modify DDPG to deep comparative policy (DCP). Rather than leveraging critic-to-actor gradient, the core training process of DCP is regulated by a T-fold compare among random proposed adjacent actions. The performance of DDPG, DCP and related algorithms are tested and compared in two experiments. Our results show that, DCP is effective, efficient and qualified to perform all tasks that DDPG can perform. More importantly, DCP is less likely to be influenced by the action space margins, DCP can provide more safety in avoiding training failure and local optimum, and gain more robustness in applications with dynamic hard margins in the action space. Another advantage is that, complex penalty for margin touching detection is not required, the reward function can always be brief and short. [ABSTRACT FROM AUTHOR]

In this paper, a highly sensitive method for sulfur ion (S 2- ) detection was developed based on a four-color fluorescence probe constructed from copper-containing metal-organic framework (CuBDC) and four dye-labeled single-strand DNA (ssDNA). In the absence of S 2- , dye-labeled ssDNA can be adsorbed on the surface of CuBDC, and the dyes are close to copper ion on the CuBDC surface, their fluorescence is quenched by copper ion, and their fluorescence signals are weak. In the presence of S 2- in the system, S 2- reacts with copper ion in CuBDC to form CuS, which has a more stable structure than complex CuBDC, resulting in the decomposition of CuBDC. In this case, dye-labeled ssDNA are detached from the CuBDC surface and dissolved in the solution, and the fluorescence of the dyes is restored. Under the optimized conditions, there is a good linear relationship between the total fluorescence intensity of four dyes and the concentration of S 2- in the range of 2 × 10 -9 to 5 × 10 -8  mol/L; the detection limit is 2.2 × 10 -10  mol/L. The method has a good selectivity and accuracy, and it can be applied to the analysis and detection of S 2- in actual water samples., (© 2024 John Wiley & Sons Ltd.)