Search

Perovskite solar cells (PSCs) have experienced exceptional development in recent years, due to their outstanding photoelectronic properties and low‐cost solution processing. Many state‐of‐the‐art PSC designs have been effectively demonstrated using a stacked 3D perovskite/2D perovskite heterostructure, yet limitations arise due to the low conductivity of the 2D perovskite, the hidden buried interface of 3D perovskite, and halide ion migration within 3D/2D PSC device under operational bias. Here, these limitations are overcome by developing a novel and universal post‐synthetic metal (Zn2+) doping strategy and realizing 3D/2D PSCs with superior efficiency and stability. Informed by ab initio calculations and synchrotron fine structure experiments, it is revealed that the introduced zinc ions are energetically favored at interstitial crystal sites, subsequently hindering the migration of halide ions and producing a beneficial shift toward a more n‐type character in the buried 3D perovskite interface. Combined with extensive photophysical characterization, the Zn2+‐modified 3D/2D perovskite thin film is shown to strongly recover its photo‐carrier conductivity compared with the 3D/2D perovskite film, boosting the efficiency (22.90%) of PSCs while exhibiting improved humidity and operational stability. [ABSTRACT FROM AUTHOR]

Purpose: This paper aims to investigate the relative translational control for multiple spacecraft formation flying. This paper proposes an engineering-friendly, structurally simple, fast and model-free control algorithm. Design/methodology/approach: This paper proposes a tanh-type self-learning control (SLC) approach with variable learning intensity (VLI) to guarantee global convergence of the tracking error. This control algorithm utilizes the controller's previous control information in addition to the current system state information and avoids complicating the control structure. Findings: The proposed approach is model-free and can obtain the control law without accurate modeling of the spacecraft formation dynamics. The tanh function can tune the magnitude of the learning intensity to reduce the control saturation behavior when the tracking error is large. Practical implications: This algorithm is model-free, robust to perturbations such as disturbances and system uncertainties, and has a simple structure that is very conducive to engineering applications. Originality/value: This paper verified the control performance of the proposed algorithm for spacecraft formation in the presence of disturbances by simulation and achieved high steady-state accuracy and response speed over comparisons. [ABSTRACT FROM AUTHOR]

Core–shell perovskite nanocrystals (NCs) have emerged as a promising class of materials for optoelectronic applications due to their unique properties and stability. Although much research has been conducted on the shell growth mechanism and properties of the core–shell NCs, little is known about the role of shell thickness in determining their optical properties. Herein, a heteroepitaxial method is employed to prepare a series of core–shell FAPbBr3/CsPbBr3 NCs with different shell thicknesses. Through temperature‐dependent photoluminescence measurement, it is found that the electronic structure of core–shell FAPbBr3/CsPbBr3 NCs evolves from quasi‐type‐II to type‐I with the increase in shell thickness. This abnormal transition can be attributed to the thickened gradient alloy layer FA1‐xCsxPbBr3, which effectively relieves the lattice mismatch and releases strain in the NCs, resulting in variations in the bandgap between the core and the shell. Furthermore, the biexciton Auger lifetimes in these samples exhibit a non‐monotonic dependence on shell thickness, indicating the electronic structure transition. These results provide valuable insights into the relationship between shell thickness, electronic structure, and optical properties in core–shell perovskite NCs, which may offer guidance for the design of high‐performance optoelectronic devices. [ABSTRACT FROM AUTHOR]

This document is a special issue of the journal "Symmetry" that focuses on recent progress in robot control systems. The issue contains fifteen papers covering various aspects of robot control, including robotics navigation and control, aircraft/spacecraft systems, and reliable designs. The papers discuss topics such as LiDAR-GPS/IMU calibration for autonomous driving, emotion recognition in human-computer interaction, and control strategies for spacecraft and aircraft. The issue also highlights other recent studies in spacecraft robot control, control of switching systems, self-learning control, state estimation of robotic systems, and trends in control systems for micro gyroscopes. The authors of the document are Chengxi Zhang, Jin Wu, and Chong Li. [Extracted from the article]

The grim situation of bacterial infection has undoubtedly become a major threat to human health. In the context of frequent use of antibiotics, a new bactericidal method is urgently needed to fight against drug-resistant bacteria caused by non-standard use of antibiotics. Cold atmospheric plasma (CAP) is composed of a variety of bactericidal species, which has excellent bactericidal effect on microbes. However, the mechanism of interaction between CAP and bacteria is not completely clear. In this paper, we summarize the mechanisms of bacterial killing by CAP in a systematic manner, discuss the responses of bacteria to CAP treatment that are considered to be related to tolerance and their underlying mechanisms, review the recent advances in bactericidal applications of CAP finally. This review indicates that CAP inhibition and tolerance of survival bacteria are a set of closely related mechanisms and suggests that there might be other mechanisms of tolerance to survival bacteria that had not been discovered yet. In conclusion, this review shows that CAP has complex and diverse bactericidal mechanisms, and has excellent bactericidal effect on bacteria at appropriate doses. Key points: • The bactericidal mechanism of CAP is complex and diverse. • There are few resistant bacteria but tolerant bacteria during CAP treatment. • There is excellent germicidal effect when CAP in combination with other disinfectants. [ABSTRACT FROM AUTHOR]

Performance of blue solution‐processed perovskite light‐emitting diodes (LEDs) is limited by availability of blue perovskite materials. Herein, 4‐(trifluoromethyl)benzoyl ammonium bromide (4‐TMBABr) is used with abundant NH and CO groups to passivate the defects and produce highly stable PEAxPA2‐x(CsPbBr3)n‐1PbBr4 perovskites for blue LED applications. The NH group in the 4‐TMBABr suppresses the Br‐ion mismatch through hydrogen bonds (N‐H···Br) and CO group coordinates the unsaturated lead dangling bonds (CO:Pb). The effective defect passivation by 4‐TMBABr reduces the nonradiative recombination in the perovskite films, hence enhancing its optical performance. In the LED structure, the sodium bis(trifluoromethanesulfonyl)imide (SBTI) modified NiOx films are used to improve the hole transport and to inhibit the fluorescence quenching of the perovskite layer. The dual‐defect manipulation strategy is advantageous for producing efficient and spectrally stable blue perovskite LEDs, and the authors demonstrate an LED with maximum luminance of 1094 cd m−2 and external quantum efficiency of 10.3%. This work can inform and underpin future development of blue perovskite LEDs with highly efficient and stabile performance. [ABSTRACT FROM AUTHOR]

Nature killer (NK) cells are increasingly considered important in tumor microenvironment, but their role in predicting the prognosis of ovarian cancer has not been revealed. This study aimed to develop a prognostic risk model for ovarian cancer based on NK cells. Firstly, differentially expressed genes (DEGs) of NK cells were found by single-cell RNA-sequencing dataset analysis. Based on six NK-cell DEGs identified by univariable, Lasso and multivariable Cox regression analyses, a prognostic risk model for serous ovarian cancer was developed in the TCGA cohort. This model was then validated in three external cohorts, and evaluated as an independent prognostic factor by multivariable Cox regression analysis together with clinical characteristics. With the investigation of the underlying mechanism, a relation between a higher risk score of this model and more immune activities in tumor microenvironment was revealed. Furthermore, a detailed inspection of infiltrated immunocytes indicated that not only quantity, but also the functional state of these immunocytes might affect prognostic risk. Additionally, the potential of this model to predict immunotherapeutic response was exhibited by evaluating the functional state of cytotoxic T lymphocytes. To conclude, this study introduced a novel prognostic risk model based on NK-cell DEGs, which might provide assistance for the personalized management of serous ovarian cancer patients. [ABSTRACT FROM AUTHOR]

Self‐assembly of nanocrystals into controlled structures while uncompromising their properties is one of the key steps in optoelectronic device fabrication. Herein, zigzag CsPbBr3 perovskite nanocrystals are demonstrated with a precise number of components with nanocube morphology, these can be successfully obtained through a dipole‐induced self‐assembly process. The addition of a trace amount of deionized water facilitates the transfer from CsPbBr3 nanocubes to intermediates of CsPb2Br5 and Cs3In2Br9, which then fastly release reaction monomers leading to further homogenous nucleation of CsPbBr3 nanocubes, followed by the formation of zigzag CsPbBr3 nanocrystals through a dipole‐induced self‐assembly process. Dipole moment along <110> axis is found to be the driving force for the assembly of nanocubes into zigzag nanocrystals. The zigzag CsPbBr3 nanocrystals exhibit desirable optical properties comparable to their nanocube counterparts and offer advantages for amplified spontaneous emission and lasing applications with low pump thresholds of 3.1 and 6.02 µJ cm−2, respectively. This study not only develops a strategy for producing highly controlled zigzag perovskite nanocrystals and provides insights on the dipole‐induced self‐assembly mechanisms, but also opens an avenue for their application in lasing. [ABSTRACT FROM AUTHOR]

Self‐assembly of nanocrystals into controlled structures while uncompromising their properties is one of the key steps in optoelectronic device fabrication. Herein, zigzag CsPbBr3 perovskite nanocrystals are demonstrated with a precise number of components with nanocube morphology, these can be successfully obtained through a dipole‐induced self‐assembly process. The addition of a trace amount of deionized water facilitates the transfer from CsPbBr3 nanocubes to intermediates of CsPb2Br5 and Cs3In2Br9, which then fastly release reaction monomers leading to further homogenous nucleation of CsPbBr3 nanocubes, followed by the formation of zigzag CsPbBr3 nanocrystals through a dipole‐induced self‐assembly process. Dipole moment along <110> axis is found to be the driving force for the assembly of nanocubes into zigzag nanocrystals. The zigzag CsPbBr3 nanocrystals exhibit desirable optical properties comparable to their nanocube counterparts and offer advantages for amplified spontaneous emission and lasing applications with low pump thresholds of 3.1 and 6.02 µJ cm−2, respectively. This study not only develops a strategy for producing highly controlled zigzag perovskite nanocrystals and provides insights on the dipole‐induced self‐assembly mechanisms, but also opens an avenue for their application in lasing. [ABSTRACT FROM AUTHOR]

The last decade has witnessed extensive breakthroughs and significant progress in atomically flat two-dimensional (2D) semiconductor nanoplatelets (NPLs) in terms of synthesis, growth mechanisms, optical and electronic properties and practical applications. Such NPLs have electronic structures similar to those of quantum wells in which excitons are predominantly confined along the vertical direction, while electrons are free to move in the lateral directions, resulting in unique optical properties, such as extremely narrow emission line width, short photoluminescence (PL) lifetime, high gain coefficient, and giant oscillator strength transition (GOST). These unique optical properties make NPLs favorable for high color purity light-emitting applications, in particular in light-emitting diodes (LEDs), backlights for liquid crystal displays (LCDs) and lasers. This review article first introduces the intrinsic characteristics of 2D semiconductor NPLs with atomic flatness. Subsequently, the approaches and mechanisms for the controlled synthesis of atomically flat NPLs are summarized followed by an insight on recent progress in the mediation of core/shell, core/crown and core/crown@shell structures by selective epitaxial growth of passivation layers on different planes of NPLs. Moreover, an overview of the unique optical properties and the associated light-emitting applications is elaborated. Despite great progress in this research field, there are some issues relating to heavy metal elements such as Cd2+ in NPLs, and the ambiguous gain mechanisms of NPLs and others are the main obstacles that prevent NPLs from widespread applications. Therefore, a perspective is included at the end of this review article, in which the current challenges in this stimulating research field are discussed and possible solutions to tackle these challenges are proposed. [ABSTRACT FROM AUTHOR]

Attitude determination is fundamental for spacecraft missions in aerospace engineering. Kalman filter (KF) is the optimal estimator in least square sense and, using the symmetry properties of matrix Lie groups system, the invariant Kalman filter (IKF) has been developed to boost the filtering performance for attitude estimation. However, due to presence of frequent and severer maneuvers, the Lie groups attitude dynamics is usually corrupted by significant biases and heavy-tailed outliers, which usually leads to decreased precision of IKF. For attitude estimation problem troubled by biased and heavy-tailed process noise, this work proposes a new invariant Kalman filter (VBAIKF) by constructing the hierarchical Gaussian system model: the probability density function of prior estimate state is first described using the student's t distribution, while the unknown scale covariance matrix and degrees of freedom (dof) of the employed student's t distribution are defined as the inverse Wishart distribution (IWD) and Gamma distribution. In VBAIKF, the Lie groups rotation matrix of spacecraft, the biased mean, the parameters of dof and scale covariance matrix are online estimated together by variational Bayesian fixed-point iterations. The simulation results with Lie groups attitude estimation system further verify the superior filtering adaptability and precision of proposed approach VBAIKF than other methods for attitude determination with biased mean and heavy-tailed process noise. [ABSTRACT FROM AUTHOR]

Perovskite solar cells (PSCs) have witnessed an unprecedentedly rapid development, especially in terms of power conversion efficiency (PCE). However, the solution‐processed perovskite films inevitably possess numerous crystallographic defects (e.g., halide vacancies), which has been shown to incur non‐radiative charge recombination and ion migration, thus limiting the enhancement of the PCE and stability of PSCs. Here, a novel dual metal (i.e., divalent and monovalent metal ions) modification strategy is reported for simultaneously reducing the defects, immobilizing the halide anions, and preventing ion loss from perovskite during post‐annealing process. Accordingly, this strategy significantly reduces non‐radiative recombination, enhancing the PCE by ≈12% and mitigating the current density‐voltage (J–V) hysteresis effect in resultant devices compared to undoped counterparts. As a result, a champion PCE exceeding 22% and a high open‐circuit voltage (Voc) of 1.16 V is obtained for dual metal ions‐modified PSCs. The optimized devices also exhibit extended lifespan upon the dual metal treatment. The study provides a new defect engineering strategy toward more efficient and stable perovskite photovoltaics. [ABSTRACT FROM AUTHOR]

This article presents integral-type edge event- and self-triggered policies for Lipschitz nonlinear multiagent systems, in which only edge states are employed by all controllers. An integral-type triggering function is designed to determine event instants, and the considered system can achieve Zeno-free triggering. An integral-type edge self-triggered policy is then designed to avoid sensors’ continuous measurements. Compared to traditional event-triggered schemes, the proposed strategies have relaxed triggering conditions and lowered the event frequencies. Also, the proposed edge self-triggered algorithm can avoid the requirement for continuous measurement error monitoring. Numerical simulations are given to demonstrate the effectiveness of the theoretical conclusions. [ABSTRACT FROM AUTHOR]

Purpose: This paper aims to study the attitude control problem with mutating orbital rate and actuator fading. Design/methodology/approach: To avoid malicious physical attacks and hide itself, the spacecraft may irregularly switch its orbit altitude within a specific range, which will bring about variations in orbital rate, thereby causing mutations in the attitude dynamics model. The actuator faults will also cause changes in system dynamics. Both factors affect the control performance. First, this paper determines the potential switching orbits. Then under different conditions, design controllers that can accommodate actuator faults according to the statistical law of actuator fading. Findings: This paper, to the best of the authors' knowledge, for the first time, introduces the Markovian jump framework to model the possible unexpected mutating of orbital rate and actuator fading of spacecraft and then designs a novel control policy to solve the attitude control problem. Practical implications: This paper also provides the algorithm design processes in detail. A comparative numerical simulation is given to verify the effectiveness of the proposed algorithm. Originality/value: This is an early solution for spacecraft attitude control with dynamics model mutations. [ABSTRACT FROM AUTHOR]

This paper introduces a novel consensus-based labeled multi-Bernoulli (LMB) filter to tackle multi-target tracking (MTT) in a communication resource-sensitive distributed sensor network (DSN). Although consensus-based approaches provide effective tools for distributed fusion and MTT, the requirement of iterative communication makes it impractical in resource limited situations. To deal with this issue, two event-triggered strategies are proposed and incorporated into the consensus-based LMB. Focusing on the information discrepancy between the local multi-target probability density function (PDF) and the time prediction of the latest broadcast one, the integral-triggering strategy (ITS) is introduced. Furthermore, by proving that the information discrepancy (Kullback-Leibler divergence) between two LMB densities with the same label space can be decomposed into the sum of the information discrepancy of each LMB component pair (LMB components with the same label), the separated-triggering strategy (STS) is proposed. The performance of the proposed algorithms is demonstrated in a distributed multi-target tracking scenario via numerical simulations. [ABSTRACT FROM AUTHOR]

The problem of simultaneous estimation of states and uncertainties by using limited information is investigated in this article. A sampled‐data learning observer (SLO) is presented for linear time‐invariant continuous systems, which can achieve successful estimation while only needs intermittent sampled‐data, saves computing resources, and does not require persistent excitation signals. The observer's demand for continuous measurement is reduced, that is, limited‐information is sufficient. Notably, the uncertainty estimation is performed by a learning equation with only simple addition operations, which is particularly suitable for actual digital system scenarios. Simulation results illustrate the effectiveness of the proposed SLO. [ABSTRACT FROM AUTHOR]

Purpose: This paper aims to propose a general and rigorous study on the propagation property of invariant errors for the model conversion of state estimation problems with discrete group affine systems. Design/methodology/approach: The evolution and operation properties of error propagation model of discrete group affine physical systems are investigated in detail. The general expressions of the propagation properties are proposed together with the rigorous proof and analysis which provide a deeper insight and are beneficial to the control and estimation of discrete group affine systems. Findings: The investigation on the state independency and log-linearity of invariant errors for discrete group affine systems are presented in this work, and it is pivotal for the convergence and stability of estimation and control of physical systems in engineering practice. The general expressions of the propagation properties are proposed together with the rigorous proof and analysis. Practical implications: An example application to the attitude dynamics of a rigid body together with the attitude estimation problem is used to illustrate the theoretical results. Originality/value: The mathematical proof and analysis of the state independency and log-linearity property are the unique and original contributions of this work. [ABSTRACT FROM AUTHOR]

Purpose: This paper aims to investigate the attitude regulation for spacecraft in the presence of time-varying inertia uncertainty and exogenous disturbances. Design/methodology/approach: The high gain approaches are typically used in existing researches for theoretical advantages, bringing better performance but sensitive to parameter selection, making the controller conservative. A reset-control policy is presented to achieve the spacecraft attitude control with easy control parameter tuning. Findings: The reset-control policy guarantees satisfying control performance despite using performance tuning function and saturation function besides reducing the conservativeness of the controller, thus reducing the effort in tuning control parameters. Originality/value: Notably, the adaptive function owns a reset mechanism, which is reset to a preset condition when the controlled variable crosses zero. The mathematical analysis also shows the system trajectory can converge to a set centered at the origin. [ABSTRACT FROM AUTHOR]

Inorganic perovskite nanocrystals (NCs) have demonstrated a number of unique optical and electronic properties for optoelectronic applications. However, the physical properties of these nanostructures, such as the dynamics of charge carriers on different timescales and their effect on the optical recombination of carriers, are not yet fully understood. This work reports on a slow (>1 s) reversible quenching of the NC photoluminescence due to a light‐induced Stark effect involving defects on the surface of the NCs and the redistribution of photoexcited carriers onto the NC surface. This phenomenon can influence the operation of optoelectronic devices based on these NCs, including hybrid photosensors based on graphene decorated with inorganic perovskite NCs, revealing their prospects and limitations. [ABSTRACT FROM AUTHOR]

This paper proposes a prescribed performance control policy for spacecraft attitude tracking control. The designed controller employs a kind of performance envelope function that can configure the convergence rate arbitrarily. Moreover, the controller design is based on the barrier Lyapunov function and indirect adaptive methods, which can suppress the fluctuation of external disturbances to obtain lower steady-state errors. Compared to prior studies on spacecraft attitude tracking, the proposed policy can arbitrarily configure the system convergence performance to achieve performance trade-offs in different scenarios. Moreover, the barrier Lyapunov function design and adaptive methods can achieve low steady-state errors with low computational resource consumption. Simulations that verify its effectiveness and superiority are provided herein. [ABSTRACT FROM AUTHOR]

Core/shell structured metal halide perovskite nanocrystals (NCs) are emerging as a type of material with remarkable optical and electronic properties. Research into this field has been developing and expanding rapidly in recent years, with significant advances in the studies of the shell growth mechanism and in understanding of properties of these materials. Significant enhancement of both the stability and the optical performance of core/shell perovskite NCs are of particular importance for their applications in optoelectronic technologies. In this review, the recent advances in core/shell structured perovskite NCs are summarized. The band structures and configurations of core/shell perovskite NCs are elaborated, the shell classification and shell engineering approaches, such as perovskites and their derivative shells, semiconductor shell, oxide shell, polymer shell, etc. are reviewed, and the shell growth mechanisms are discussed. The prospective of these NCs in lighting and displays, solar cells, photodetectors, and other devices is discussed in the light of current knowledge, remaining challenges, and future opportunities. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this paper is to study the general actuator modeling in spacecraft attitude control systems. Design/methodology/approach: The proposed module in this paper provides various non-ideal factors such as the second-order dynamic time response, time-delay, bias torques, dead-zones and saturation. The actuator module can make the simulation as close to the practical situation as possible. Findings: This paper presents a practical integrated module for the simulation of attitude control algorithms. Based on theoretical modeling, we give simulation modules and numerical examples. The proposed model can be directly used in spacecraft control simulation. Instead of considering only a few of them, it makes the simulation more convincing. Though it may not be perfect, it is better than totally ignoring the actuator dynamics. Originality/value: The authors provide an integrated actuator model for spacecraft attitude control simulation, considering as many nonlinear factors as possible once time. [ABSTRACT FROM AUTHOR]

Fast deactivation is a long-standing problem for zeolite catalyzed isobutane-butene alkylation that hinders its massive industrialization, and the optimization of the zeolites' acidity and pore structure is the key problem. A synergistic F-containing solution modification method was proposed to improve the diffusion performance without damaging the zeolites' acidity. The low-temperature ammonium fluoride treatment precise partly opened the cage windows of the zeolites to increase the acidity accessibility and diffusion performance. And the following acid treatment of ammonium fluosilicate effectively removed the extra-framework aluminum generated by the former treatment to achieve a high acidity and Brönsted acid amount to Lewis acid amount ratio. The best modified zeolite Y-11 has a lifetime of 60 h, which is 32% higher compared to that of the reference zeolite. Our primary results provide a promising strategy for designing superior zeolite catalysts for alkylation reactions. A synergistic F-containing solution modification method was proposed to improve the diffusion performance without damaging the zeolites' acidity, which have promoted the catalyst's alkylation stability. [Display omitted] • A synergistic modification method was proposed to improve the diffusion performance without damaging the acidity. • The NH 4 F treatment precise opened the cage windows of the zeolites to increase the acidity accessibility and diffusion. • The best modified zeolite Y-11 has a lifetime of 60 h, which is 32% higher compared to that of the reference zeolite. [ABSTRACT FROM AUTHOR]

The existing event-triggered (ET) strategies for distributed multi-target filter commonly employ triggering conditions focusing on the instantaneous information discrepancy. Although this approach can save communication resource, it suffers from its sensitivity to instantaneous disturbance and outliers that results in unnecessary communications. In this correspondence, an integral-type event-triggered mechanism is integrated with the consensus-based labeled multi-Bernoulli filter (LMB). The proposed algorithm provides a passivation effect that lowers the communication activities while preserving the tracking performance in the uncertain environment with disturbance. The theoretical analysis demonstrates that the integral-type event-triggered mechanism introduces bounded information discrepancy in the sense of Kullback–Leibler (KL) divergence. The proposed algorithm is also verified by numerical simulations in a target tracking scenario. • Integral term is introduced into the ET-based consensus-based LMB filter. • The proposed solution is insensitive to the instantaneous disturbance and outliers. • The theoretical analyses of the stability are provided. [ABSTRACT FROM AUTHOR]

Purpose: Recent spacecraft attitude control systems tend to use wireless communication for cost-saving and distributed mission purposes while encountering limited communication resources and data exposure issues. This paper aims to study the attitude control problem with low communication frequency under the sampled-data. Design/methodology/approach: The authors propose constructive control system structures based on quantization and event-triggered methods for intra-spacecraft and multi-spacecraft systems, and they also provide potential solutions to shield the control system's data security. The proposed control architectures can effectively save communication resources for both intra-spacecraft and multi-spacecraft systems. Findings: The proposed control architectures no longer require sensors with trigger-ing mechanism and can achieve distributed control schemes. This paper also provides proposals of employing the public key encryption to secure the data in control-loop, which is transmitted by the event-triggered control mechanism. Practical implications: Spacecraft attempts to use wireless communication, yet the attitude control system does not follow up promptly to accommodate these variations. Compared with existing approaches, the proposed control structures can save communication resources of control-loop in multi-sections effectively, and systematically, by rationally configuring the location of quantization and event-triggered mechanisms. Originality/value: This paper presents several new control schemes and a necessary condition for the employment of encryption algorithms for control systems based on event-based communication. [ABSTRACT FROM AUTHOR]

Lead halide perovskite nanocrystals (PeNCs) are promising materials for applications in optoelectronics. However, their environmental instability remains to be addressed to enable their advancement into industry. Here the development of a novel synthesis method is reported for monodispersed PeNCs coated with all inorganic shell of cesium lead bromide (CsPbBr3) grown epitaxially on the surface of formamidinium lead bromide (FAPbBr3) NCs. The formed FAPbBr3/CsPbBr3 NCs have photoluminescence in the visible range 460–560 nm with narrow emission linewidth (20 nm) and high optical quantum yield, photoluminescence quantum yield (PLQY) up to 93%. The core/shell perovskites have enhanced optical stability under ambient conditions (70 d) and under ultraviolet radiation (50 h). The enhanced properties are attributed to overgrowth of FAPbBr3 with all‐inorganic CsPbBr3 shell, which acts as a protective layer and enables effective passivation of the surface defects. The use of these green‐emitting core/shell FAPbBr3/CsPbBr3 NCs is demonstrated in light‐emitting diodes (LEDs) and significant enhancement of their performance is achieved compared to core only FAPbBr3‐LEDs. The maximum current efficiency observed in core/shell NC LED is 19.75 cd A‐1 and the external quantum efficiency of 8.1%, which are approximately four times and approximately eight times higher, respectively, compared to core‐only devices. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this paper is to investigate the attitude cooperation control of multi-spacecraft with in-continuous communication. Design/methodology/approach: A decentralized state-irrelevant event-triggered control policy is proposed to reduce control updating frequency and further achieve in-continuous communication by introducing a self-triggered mechanism. Findings: Each spacecraft transmits data independently, without the requirement for the whole system to communicate simultaneously. The local predictions and self-triggered mechanism avoid continuous monitoring of the triggering condition. Research limitations/implications: This investigation is suitable for small Euler angle conditions. Practical implications: The control policy based on event-triggered communication can provide potential solutions for saving communication resources. Originality/value: This investigation uses event- and self-triggered policy to achieve in-communication for the multi-spacecraft system. [ABSTRACT FROM AUTHOR]

We, for the first time, correlated the alkyl chain length of amine molecules with the defect passivation efficacy, either on the surfaces or at grain boundaries of perovskite films. Blade-coated perovskite solar cells with long-chain amine passivation achieved an efficiency of 21.5%, accompanied by a small voltage loss of 0.35 V. [ABSTRACT FROM AUTHOR]

Herein, we report a modular synthetic approach of (C-10 to C-13)-substituted 9,14-diaryl-9,14-dihydrodibenzo[a,c]phenazine derivatives. This synthetic route enables the aromatic substitution in a predictable and programmed manner to obtain products in synthetically useful isolated yield. [ABSTRACT FROM AUTHOR]

Microorganisms produce biologically active natural products, some of which are useful as antibiotics and other medicines. A great demand for new antibiotics exists due to the diversity of pathogens and their mechanisms of drug resistance. Antibiotics were discovered as natural metabolites that enable a microorganism to suppress the growth of a competitor. Although the pace of discovery has slowed dramatically, new approaches to identifying antibiotics show promise for the future. Among many modern approaches to discovery, co-culturing different species and understanding the molecular bases of their interactions is opening new windows to antibiotic discovery. Here we review several examples to illustrate how co-culturing as an approach is producing new insights into the biology of specialized metabolism. Understanding the varied functions of specialized metabolites, combined with use of innovative and advanced analytical tools, indicates that studies of microbial interactions will enhance the discovery of new antibiotics and other natural products. [ABSTRACT FROM AUTHOR]

Abstract The attitude cooperative control of multi-spacecraft under undirected information flow is studied in this paper based on a novel state-irrelevant event-triggered control (ETC) strategy. In the proposed algorithm, the control updating and data-transfer among spacecraft need only be executed when certain conditions are triggered. Then, the system model is utilized to predict the future state based on the last transmission and to calculate the time of the next transmission event. Firstly, the proposed algorithm reduces the control updating frequency remarkably and avoids continuous communication; secondly, each spacecraft updates its controller independently, without requiring all members to update simultaneously; thirdly, it is still effective in the presence of input limitation. The consensus can be guaranteed under such control strategy. It has proved that there exists a lower bound for the update interval, avoiding a phenomenon that the infinite number of events may appear in a finite time interval, also called the Zeno phenomenon. The efficacy of the proposed algorithm is verified via simulations. [ABSTRACT FROM AUTHOR]

This study aimed to investigate whether recombinant human brain natriuretic peptide (rhBNP) regulated hypoxia-induced injury in H9c2 cardiomyocytes through lncRNA EGOT. H9c2 cardiomyocytes were cultured under normoxia and hypoxia (21% and 3% O 2 ) conditions, and whether hypoxia induced injury by assessing cell viability, apoptosis and autophagy. H9c2 cells were then treated with different doses of exogenous rhBNP (200, 600 and 900 nmol/L, respectively) and the effects of rhBNP on hypoxia-induced injury in H9c2 cells as well as the expression of EGOT were studied. In addition, the regulatory relationships between rhBNP and EGOT as well as between rhBNP and PI3K/AKT/mTOR pathway in hypoxia-treated H9c2 cells were investigated. Hypoxia significantly induced injury in H9c2 cells (inhibited cell viability and promoted cell apoptosis and autophagy) and decreased the expression of EGOT. However, administration of rhBNP alleviated hypoxia-induced injury in H9c2 cells and elevated expression of EGOT. Suppression of EGOT significantly reversed the effects of rhBNP on hypoxia-induced injury in H9c2 cells. Further studies showed that the effects of EGOT on cell viability and apoptosis were by positively regulating the expression of Cyclin D1. Moreover, rhBNP alleviated hypoxia-induced cell injury by activating PI3K/AKT/mTOR pathway in H9c2 cells. Our results reveal that rhBNP may play a protective role in attenuating hypoxia-induced injury in H9c2 cardiomyocytes via regulating lncRNA EGOT/Cyclin D1/PI3K/AKT/mTOR pathway axis. The findings will provide a new strategy for the treatment of heart failure induced by hypoxia. [ABSTRACT FROM AUTHOR]

This paper addresses the attitude control problem to spacecraft against actuator faults. A novel observer based event-triggered control (OETC) approach is proposed to cope with external disturbances, actuator faults and reduce the control updating frequency. First, a learning observer (LO) is utilized to reconstruct actuator faults and disturbances. Then, based on the LO, an event-triggered control (ETC) scheme is designed to achieve attitude stabilization from the reconstructed knowledge. The innovation is that the integrated OETC possesses resource-saving advantages of both LO and ETC, which haven't been used before. Moreover, the design method is simple and easy to operate. Simulations are given to demonstrate the validities of the proposed algorithm. [ABSTRACT FROM AUTHOR]

This paper addresses the attitude synchronization and tracking control (ASTC) for multi-spacecraft formation system (MFS) under undirected and directed graph. First, a new adaptive nonsingular fast terminal sliding mode surface (ANFTSMS) is developed. It has both the merits of the NFTSM avoiding singularity and the adaptive method regulating the relative weighting of parameters. This provides designers a new way to improve the control performance. Second, by applying ANFTSMS, the proposed ANFTSM-controllers (ANFTSMCs) provide high precision finite-time convergence, robust to time-varying disturbances, uncertainties and accommodate to actuator faults, limited inputs. Moreover, the ANFTSMCs also achieve simple structure, inexpensive computations and chattering-free for continuous design. Few studies have addressed these problems simultaneously. Finally, effectiveness of the algorithms are verified via simulations. [ABSTRACT FROM AUTHOR]

Herein, we reported that the platinum (Pt) clusters encapsulated into sodalite (SOD) zeolite as catalyst exhibited 100 % selectivity at 100 % conversion in the selective hydrogenation of p‐chloronitrobenzene to p‐chloroaniline via hydrogen spillover. The direct interaction between p‐chloronitrobenzene and encapsulated Pt was prevented by the shape selectivity of SOD zeolite, reactants were thereby adsorbed onto zeolite outer surface to facilitate the hydrogenation proceeding by hydrogen spillover process. The further kinetic study and DFT calculation showed the excellent catalytic selectivity was ascribed to the much faster rate of hydrogenation of adsorbed nitro group than that of adsorbed C−Cl group. [ABSTRACT FROM AUTHOR]

Plug-and-play modular design is the future of spacecraft manufacturing. The employment of wireless communication between different modules instead of wire connections can reduce weight and simplify assembly. This paper focuses on the design of spacecraft attitude tracking control policies under wireless communications. A new event-based control policy with performance adjustable functions is proposed to achieve intermittent sampling to save system resources. Under the designed policy, the sampling frequency and convergence rate of the considered system can be traded off by designing different performance adjustable functions. Based on the Lyapunov function method, it proves that the spacecraft attitude tracking errors are uniformly ultimately bounded. In comparison with the previous results, the proposed policy provides a more general triggering condition and has the property of freely adjustable performance, which is suitable for scenarios with different performance requirements. Numerical simulations support the conclusion of its effectiveness and superiority. [ABSTRACT FROM AUTHOR]

Nanocrystal/polymer solid solar cells have the advantages of low-cost, simple process, and flexible manufacture. In this work, ternary solid solar cells based on FeS 2 and PbS nanocrystals exhibited photovoltaic conversion efficiency of 3.0% and 3.1%, respectively. As a kind of semiconductor with optical absorption in the visible and near-infrared regions, FeS 2 nanocrystals matched well with the solar radiation spectrum. Furthermore, PbS Nanocrystals could increase the number of electrons, due to its multiple exciton effect. Additionally, the FeS 2 nanocrystals solar cells showed high stability, with 83.3% of its initial efficiency remained after 15 weeks of exposure in air, and kept good stable performance at 20–80 °C. The photovoltaic conversion efficiency fluctuation magnitudes were also found to be smaller than quantum-dot sensitized solar cell under the same conditions. [ABSTRACT FROM AUTHOR]

Correction for 'Atomically flat semiconductor nanoplatelets for light-emitting applications' by Bing Bai et al., Chem. Soc. Rev., 2023, 52, 318–360, https://doi.org/10.1039/D2CS00130F. [ABSTRACT FROM AUTHOR]

The inverted polymer solar cell was prepared by self-made spray-coating system, and the poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) hole transport layer was studied. 220 nm poly-(3-hexylthiophene):[6,6]-phenylC61butyric-acid methyl-ester (P3HT:PCBM) and 40 nm PEDOT:PSS were deposited on ZnO thin film subsequently by solution spray coating. Different volume of isopropyl alcohol was introduced into PEDOT:PSS to decrease the contact angle and obtain the optimum Marangoni flow. The surface morphology and roughness of PEDOT:PSS films were characterized by atomic force microscopy with varied deposition temperature from 70°C to 160°C. The improvement of power conversion efficiency (PCE) was attributed to the enhancement of vertical phase separation in PEDOT:PSS film, which improved the charge transfer in the bulk cell. The highest PCE of spray-coated PSCs reached 2.80% after postannealing for 10 min. [ABSTRACT FROM AUTHOR]

This paper investigates the attitude fault-tolerant stabilization problem for a spacecraft subjected to its actuator effectiveness loss, inertia uncertainties and space disturbances. A novel Iterative Learning Sliding Mode Observer (ILSMO) is proposed to reconstruct the actuator effectiveness factors robustly and accurately by combining the P-type iterative learning algorithm with the sliding mode approach. Based on the reconstructed fault signals, an Iterative Learning Sliding Mode Controller (ILSMC) is designed to guarantee the closed-loop spacecraft attitude fault-tolerant stabilization by compensating for its lumped disturbance. The ILSMO and ILSMC stabilities are guaranteed using the Lyapunov direct approach, respectively. Finally, the numerical simulation results show that the proposed ILSMO-ILSMC-based spacecraft attitude fault-tolerant stabilization method is effective and superior. [ABSTRACT FROM AUTHOR]

Cardanol-based benzoxazine (Bz-C) was introduced to a ternary resin system to substitute carboxyl-terminated butadiene–acrylonitrile (CTBN) partially and improve the thermal and dielectric properties of the diglycidyl ether of bisphenol-A (epoxy)/4,4′-diaminodiphenylsulfone (DDS)/CTBN adhesive resin system. The effect of Bz-C on the curing behavior of blends was studied, and factors that affect the thermal, mechanical, and dielectric properties were discussed systematically. Results show that reactions between Ep, DDS, and Bz-C decrease the curing temperature of the quaternary blends and increase the cross-linking densities of the network, leading to higher glass-transition temperature and enhanced mechanical properties. The flexibility of the copolymer films was maintained by the introduction of the aliphatic side chain of Bz-C. Substitution of Bz-C for some group of CTBN in the cross-linked network resulted in decreased dielectric constant and dielectric loss in the copolymer films. [ABSTRACT FROM PUBLISHER]

Highlights: [•] A nanoconfined Ni-CeO2 catalyst was successfully prepared by an ball-milling method. [•] The Ni-CeO2 catalyst has strong metal–support interaction and high oxygen mobility compared. [•] The Ni-CeO2 catalyst has a high activity in ESR with a yield of at 350°C. [•] The Ni-CeO2 catalyst is superior stable even upon a 2h severe thermal treatment. [ABSTRACT FROM AUTHOR]

To handle the potential collision hazards caused by utilizing original fuel optimal impulsive reconfiguration approach, an analytical impulsive satellite formation reconfiguration method in terms of relative eccentricity and inclination vectors (E/I vectors) considering passive safety constraints is proposed. Firstly, the mechanism why original fuel optimal impulsive reconfiguration approach based on relative E/I vectors may cause unsatisfied collision avoidance constraints is analyzed. The unsatisfied scenarios are divided into two cases, namely, the single impulse is too large case and the middle relative E vector is in passive unsafety region case. Secondly, with respect to the unsatisfied collision avoidance scenarios, corresponding analytical impulsive reconfiguration strategies with passive safety constraints are proposed. Finally, the results of the numerical simulations show that the proposed reconfiguration methods can handle the passive safety constraints. [ABSTRACT FROM AUTHOR]

This brief investigates the problem of attitude tracking control using a variable learning intensity (VLI) online-learning control (OLC) scheme. The unique specialty of the proposed VLI-OLC scheme is that it achieves control performance enhancement via learning the previous control information online. The implementation is performed by a simple algebraic equation, which achieves decent control robustness while avoiding a complex control design and saving computational resources. The OLC's saturation response caused by the extensive system error during execution is noticeably weakened by introducing a VLI approach. Compatibility with previous algorithms can be guaranteed. The application example shows that control performance and saturation reduction are guaranteed concurrently. [ABSTRACT FROM AUTHOR]

This paper proposes a neural network and event-based fault-tolerant control scheme for spacecraft attitude stabilization in the presence of lumped disturbances, which consists of space disturbances, inertia uncertainties, and actuator faults. A neuro-adaptive estimator is employed to approximate the lumped disturbances, with the help of its powerful adaptive estimation capability of approximating any unknown smooth nonlinear function with arbitrary accuracy. The estimation is then utilized to formulate an integrated event-based dual-channel control scheme that can both guarantee the system's convergence and ensure the event triggering sequence possessing no-Zeno behavior simultaneously. The proposed control scheme provides a new and straightforward way for spacecraft attitude control to deal with lumped disturbances while requiring a low actuator updating frequency, thus saves on-board communication resources. Numerical simulations show the effectiveness of the algorithms. [ABSTRACT FROM AUTHOR]

In order to meet the constraints of velocity and acceleration of displacement and attitude motion of an unmanned helicopter during an automatic carrier landing mission, an asymmetric tracking differentiator, which could set the speed and acceleration limits in two directions of tracked signal motion respectively, was derived based on the tracking differentiator in the active disturbance rejection control method. Based on the proposed asymmetric tracking differentiator, a fal-extended state observer based on the fal function was added to construct the attitude and angular velocity controller which is programmable during the transition process of unmanned helicopters. The mathematical simulation and result analysis show that the newly proposed attitude estimation algorithm effectively compensates for the deficiencies of the existing methods, improves the anti-jamming capability and the accuracy of attitude estimation in the maneuvering process, achieving the expected design purposes. [ABSTRACT FROM AUTHOR]

The modular robotic arms can achieve desired performances in different scenarios through the combination of various modules, and concurrently hold the potential to exhibit geometric symmetry and uniform mass symmetry. Therefore, selecting the appropriate combination of modules is crucial for realizing the functions of the robotic arm and ensuring the elegance of the system. To this end, this paper proposes a double deep Q-network (DDQN)-based configuration design algorithm for modular robotic arms, which aims to find the optimal configuration under different tasks. First, a library of small modules of collaborative robotic arms consisting of multiple tandem robotic arms is constructed. These modules are described in a standard format that can be directly imported into the software for simulation, providing greater convenience and flexibility in the development of modular robotic arms. Subsequently, the DDQN design framework for module selection is established to obtain the optimal robotic arm configuration. The proposed method could deal with the overestimation problem in the traditional deep Q-network (DQN) method and improve the estimation accuracy of the value function for each module. In addition, the experience replay mechanism is improved based on the SumTree technique, which enables the algorithm to make effective use of historical experience and prevents the algorithm from falling into local optimal solutions. Finally, comparative experiments are carried out on the PyBullet simulation platform to verify the effectiveness and superiority of the configuration design method developed in the paper. The simulation results show that the proposed DDQN-based method with experience replay mechanism has higher search efficiency and accuracy compared to the traditional DQN scheme. [ABSTRACT FROM AUTHOR]

Summary: This article investigates the issue of orbit coordination control for a class of multi‐spacecraft formation systems in presence of limited communication and external disturbance. To solve the limitation of communication sources, a dynamic event trigger (DET) mechanism is developed to reduce the communication frequency between the follower spacecrafts. Subsequently, we explore a robust DET mechanism‐based distributed self‐learning sliding mode control design, in which a variable learning intensity‐based iterative learning algorithm is designed to approximate and compensate space perturbation. This approach can guarantee an event triggering sequence without Zeno phenomenon and accurate coordination control for formation configuration simultaneously. Compared with the traditional event‐triggered control and other state‐of‐the‐art approaches, the distributed DET control scheme achieves higher control accuracy of formation configuration meanwhile requires less communication resource. Finally, a series of numerical simulations demonstrate the feasibility and superiority of the event triggered control method. [ABSTRACT FROM AUTHOR]

This paper studies the spacecraft attitude stabilization problem with external disturbances. A new control scheme entitled online-learning control is proposed to achieve a robust, accurate, and simple-structure control algorithm. Compared with the conventional control design, an obvious distinction of the online-learning control algorithm is that it together utilizes the previous control input information and the system's current state information, as if learning experience from previous control input. In contrast, the conventional control scheme does not fully use the existing information and chooses to discard the previous control input information when generating control instructions. Due to the learning strategy, the utility of adaptive- or observer-based tools can be avoided when designing a robust control law, making a simple, effective algorithm, moreover saving system resources. The proposed control law can stabilize the attitude system by achieving the uniformly ultimately bounded convergence. [ABSTRACT FROM AUTHOR]