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Metal-halide perovskites(MHPs) have attracted widespread attention as the next-generation luminescent materials due to their excellent emission characteristics, such as narrowband emission and tunable color. Compared with hybrid perovskites, all-inorganic perovskites have better thermal and chemical stability and can therefore provide the basis for high-performance light-emitting diodes (LEDs) with reasonable operating stability. However, due to the large grain size and relatively poor surface quality of inorganic perovskites, the radiation recombination efficiency is inefficient, leading to a reduced efficiency of LED devices. Here, we employed the additive [2-(9H-carbazol-9-yl)ethyl]phosphonic acid (2PACz) for a straightforward in situ reaction with three-dimensional (3-D) inorganic perovskite. 2PACz forms a covalent bond with under-coordinated lead atoms on the perovskite surface, effectively passivating surface defects and enhancing radiative recombination efficiency. Simultaneously, crystal growth was controlled to obtain high-quality inorganic perovskite thin films with a smooth surface and small grain size. This approach not only reduces trap density in the perovskite but also maintains excellent charge transport characteristics of 3-D perovskite. Consequently, we fabricated a perovskite light-emitting diode (PeLED) with a maximum brightness of 13 192 cd m−2, an external quantum efficiency (EQE) of up to 20.87%, and a half-lifetime of 479 h (at 100 cd m−2).

With a stacking-layered architecture, the bilayer two-dimensional-three-dimensional (2D-3D) perovskite heterostructure (PHS) not only eliminates surface defects but also protects the 3D perovskite matrix from external stimuli. However, these bilayer 2D-3D PHSs suffer from impaired interfacial charge carrier transport due to the relatively insulating 2D perovskite fragments with a random phase distribution. Over the past decade, substantial efforts have been devoted to pioneering molecular and structural designs of the 2D perovskite interlayers for improving their charge carrier mobility, which enables state-of-the-art perovskite solar cells with high power conversion efficiency and exceptional operational stability. Herein, this review offers a comprehensive and up-to-date overview on the recent progress of bilayer 2D-3D PHSs, encompassing advancements on spacer cation engineering, interfacial charge carrier modification, advanced deposition protocols, and characterization techniques. Then, the evolutionary trajectory of bilayer 2D-3D PHSs is outlined by summarizing its mainstream development trends, followed by a perspective discussion about its future research opportunities toward efficient and durable perovskite solar cells.

Given the complex flight mission and structural characteristics of special-shaped tanks in new-generation space vehicles, this study investigates the sloshing characteristics and suppression methods of liquid propellant. Initially, the numerical calculation and structural suppression approaches for liquid propellant periodic sloshing are introduced. Subsequently, a new equivalent dynamic analysis approach based on the Volume of Fluid (VOF) method is presented and validated to simulate liquid sloshing and determine dynamic characteristic parameters such as sloshing mass, frequency, and damping ratio. Furthermore, anti-sloshing baffles are designed for sloshing suppression, and the influence of baffle height on sloshing frequency and damping ratio is examined. These significant findings provide crucial references and foundations for enhancing the flight stability and reliability of the attitude control system in new-generation space vehicles.

This article presents an active fault-tolerant formation control method based on learning neural network approaches for elliptical orbit spacecraft with thruster faults. To approximate thruster fault/synthesized perturbation online, we propose a learning radial basis function neural network (RBFNN) model in which the iterative learning algorithm with one algebraic iteration is first adopted to update the weight matrix of the RBFNN. Compared with conventional adaptive RBFNN models, the proposed learning RBFNN model requires fewer computations and allows for discontinuous output measurement. A learning neural network sliding mode observer is explored to accurately and robustly reconstruct the thruster fault and estimate the relative state of the formation. Subsequently, a learning neural network sliding mode control (SMC) law is designed to achieve accurate fault-tolerant configuration tracking for maintenance, in which the learning RBFNN model is used to online approximate and compensate for synthesized perturbations. Compared with the nonlinear terminal SMC method, the proposed control approach exhibits higher tracking accuracy for configuration maintenance without requiring massive computation. Numerical simulations and detailed comparisons are provided to illustrate the feasibility and superiority of the presented spacecraft fault-tolerant formation control approach.

The space-based gravitational wave (GW) detecting satellite's drag-free control system contains two test masses (TMs), and the relative translational motion between the three is coupled. Unlike the conventional single TM drag-free satellite, the double TMs drag-free satellite in GW detection cannot track the two TMs simultaneously with six relative translational degrees of freedom. Therefore, a suitable drag-free tracking approach is necessary to be chosen between the satellite and the two TMs to meet the residual acceleration demand in the direction of the TMs’ sensitivity axis. Different drag-free tracking techniques correspond to various decoupling feedback techniques, which result in various control performances between two TMs and a corresponding impact on fuel consumption. First, a new virtual point tracking approach that offers several possibilities for choosing drag-free reference points is provided after analyzing the virtual point tracking strategy used by the double TMs GW detection satellite. The position of the fuel optimal reference point is then determined. Additionally, the proposed tracking approach can reduce fuel consumption by about 15.8% at the fuel optimal reference point, and the results of the numerical simulations demonstrate excellent agreement with our hypothesis. The suggested tracking approach incorporates the mission requirements and fuel consumption, which can reduce fuel consumption and significantly lengthen the time of the satellite detection mission while maintaining the mission demands. This is in contrast to the current tracking technique.

This paper expounds on the development status and relevant works of control and guidance methods of the aerospace vehicle in recent years. The control difficulties and the solutions in the related results are introduced briefly. Moreover, the guidance methods are then expounded in detail according to the flight phases of the whole flight mission. Guidance methods are usually included in each phase, and the corresponding trajectory design theories are also introduced where necessary. In addition, the potential future development direction prospects. Based on the above, a brief conclusion is then made as a summary.

For continuous-discrete filtering with strong nonlinearity and large measurement intervals, a Log-Euclidean metric (LEM) based novel continuous-discrete cubature Kalman filter (LEMCDCKF) is proposed by shifting the cubature rule-based covariance propagation to Riemannian manifold. In conventional CDCKFs, the covariance differential equation based on cubature points is solved with Euclidean space integration schemes, which inevitably ignore the geometric property and restrict the performance of CDCKF. To remedy this shortage, we propose to define covariance on Riemannian symmetric positive definite (SPD) manifold and integrate the cubature rule-based covariance differential equation with the LEM-based novel scheme, which can successfully account for the manifold property of covariance matrices and provide accurate results. Moreover, by refining CDCKF with the LEM based scheme, the proposed LEMCDCKF shifts the covariance integration process to SPD manifold, which can break through the limitation of Euclidean numerical scheme. Numerical investigations verify the superior performance of the proposed LEMCDCKF in air traffic control scenarios with large measurement intervals.

The aim of this paper is to analyze dynamic characteristics and stability of magnetic sail-based planetary displaced orbits, and the feasibility of using a magnetic sail as an advanced propellantless control technology for formation flying around elliptic planetary displaced orbits (EPDOs). The thrust can be obtained from the momentum exchange between solar wind and an artificial magnetic field. First, the requirements of a magnetic sail for generating and maintaining a planetary circular displaced orbit is discussed including the value of attitude angles and characteristic acceleration. Based on different orbital periods, the circular displaced orbits are divided into three types and their linear stability is analyzed. For elliptical orbits, the conditions required to maintain an EPDO are investigated and the dynamical models of magnetic sail formation system are established. A finite time coordinated control algorithms relying on the protocols formulated on an undirected communication graph is proposed to achieve synchronized formation tracking rapidly while enhancing the robustness of formation system due to information interaction between spacecraft. Several numerical simulations are conducted to demonstrate that spacecraft formation can be effectively controlled by the proposed propellantless propulsion system.

Despite the rapid progress in perovskite light-emitting diodes (PeLEDs), the electroluminescence performance of large-area perovskite devices lags far behind that of laboratory-size ones. Here, we report a 3.5 cm × 3.5 cm large-area PeLED with a record-high external quantum efficiency of 12.1% by creating an amphipathic molecular interface modifier of betaine citrate (BC) between the perovskite layer and the underlying hole transport layer (HTL). It is found that the surface wettability for various HTLs can be efficiently improved as a result of the coexistence of methyl and carboxyl groups in the BC molecules that makes favorable groups to selectively contact with the HTL surface and increases the surface free energy, which greatly facilitates the scalable process of solution-processed perovskite films. Moreover, the luminous performance of perovskite emitters is simultaneously enhanced through the coordination between C═O in the carboxyl groups and Pb dangling bonds.

The generalized rigid registration problem in high-dimensional Euclidean spaces is studied. The loss function is minimized with an equivalent error formulation by the Cayley formula. The closed-form linear least-square solution to such a problem is derived which generates the registration covariances, i.e., uncertainty information of rotation and translation, providing quite accurate probabilistic descriptions. Simulation results indicate the correctness of the proposed method and also present its efficiency on computation-time consumption, compared with previous algorithms using singular value decomposition (SVD) and linear matrix inequality (LMI). The proposed scheme is then applied to an interpolation problem on the special Euclidean group $SE(n)$ with covariance-preserving functionality. Finally, experiments on covariance-aided Lidar mapping show practical superiority in robotic navigation.

The existing event-triggered distributed multi-target filters utilize a constant triggering threshold. Although the communication burden is reduced, it does not adapt well to dynamic environments. In this brief, a novel consensus-based labeled multi-Bernoulli (LMB) filter with event-triggered strategy is introduced with the triggering threshold being decided by a bounded threshold function. The theoretical analysis proves that the information discrepancy of the proposed algorithm is bounded in Kullback-Leibler (KL) divergence sense. The performance of the proposed algorithms is demonstrated in a distributed multi-target tracking scenario via numerical simulations.

The highly diastereoselective dicarbofunctionalization of substituted olefins still remains a daunting challenge in synthetic chemistry. Herein, we report a Pd-catalyzed diastereoselective 1,1-diarylation of 1,1-diarylethylene with chelation group free to enable the modular synthesis of smart material candidates, 1,1,2,2-tetraarylethanes (TAEs), which represent the first protocol by assembling four different aryl groups into ethane motif. Preliminary mechanistic experiments suggest that the crucial Pd-H species generated in situdo not disengage from the alkene intermediate during the reaction.

This article investigates an iterative finite impulse response (FIR) filter for a nonlinear system with model uncertainties. We begin by designing a simple initialization method for the iterative FIR structure and use the unscented transformation (UT) to realize iterative state estimation in each finite horizon. Additionally, a compensation variable is introduced to compensate for the inaccuracies in the nonlinear dynamic model, thereby reducing uncertainties and improving the estimation accuracy. To estimate the compensation variable, we employ the variational Bayesian (VB) method. Compared with other filters, our design can not only avoid calculating the Jacobian matrix and batch processing to reduce computational load but also enhance robustness. Simulation results demonstrate the validity of the proposed filter.

Unnatural chiral α-tertiary amino acids containing two different carbon-based substituents at the α-carbon centre are widespread in biologically active molecules. This sterically rigid scaffold is becoming a growing research interest in drug discovery. However, a robust protocol for chiral α-tertiary amino acid synthesis remains scarce due to the challenge of stereoselectively constructing sterically encumbered tetrasubstituted stereogenic carbon centres. Herein we report a cobalt-catalysed enantioselective aza-Barbier reaction of ketimines with various unactivated alkyl halides, including alkyl iodides, alkyl bromides and alkyl chlorides, enabling the formation of chiral α-tertiary amino esters with a high level of enantioselectivity and excellent functional group tolerance. Primary, secondary and tertiary organoelectrophiles are all tolerated in this asymmetric reductive addition protocol, which provides a complementary method for the well-exploited enantioselective nucleophilic addition with moisture- and air-sensitive organometallic reagents. Moreover, the three-component transformation of α-ketoester, amine and alkyl halide represents a formal asymmetric deoxygenative alkylamination of the carbonyl group.

This article addresses the multiagent systems consensus control problem via a learning observer-based performance tuning control policy. Specifically, a novel learning observer is presented to reconstruct the compound nonlinear terms and system states simultaneously. Based on the learning observer’s reconstructed information, a novel performance tuning control policy is proposed to deal with the internal nonlinear terms and external disturbances acting on the system while providing prescribed consensus performance. The proposed learning observer can guarantee the uniformly ultimately bounded estimation while saving computing resources, which is beneficial to the multiagent system. The proposed control policy, combined with observer and performance tuning, ensures the robustness to nonideal perturbations and the high accuracy control performance simultaneously. Mathematical simulations verify the effectiveness of the control algorithm.

Perovskite nanoplatelets (NPLs) show great potential for high-color-purity light-emitting diodes (LEDs) due to their narrow line width and high exciton binding energy. However, the performance of perovskite NPL LEDs lags far behind perovskite quantum dot-/film-based LEDs, owing to their material instability and poor carrier transport. Here, we achieved efficient and stable pure blue-emitting CsPbBr3NPLs with outstanding optical and electrical properties by using an aromatic ligand, 4-bromothiophene-2-carboxaldehyde (BTC). The BTC ligands with thiophene groups can guide two-dimensional growth and inhibit out-of-plane ripening of CsPbBr3NPLs, which, meanwhile, increases their structural stability via strongly interacting with PbBr64–octahedra. Moreover, aromatic structures with delocalized π-bonds facilitate charge transport, diminish band tail states, and suppress Auger processes in CsPbBr3NPLs. Consequently, the LEDs demonstrate efficient and color-stable blue emissions at 465 nm with a narrow emission line width of 17 nm and a maximum external quantum efficiency (EQE) of 5.4%, representing the state-of-the-art CsPbBr3NPL LEDs.

This paper proposes a novel fast deterministic quaternion attitude determination method for accelerometer and magnetometer combination (AMC). After taking insight to the attitude determination theory, an important relationship between the sensor outputs and the magnetometer’s reference vector is successfully derived. Based on the relationship, the optimal quaternion associated with the attitude of a certain object is easily calculated. The main breakthrough of this paper is that it significantly simplifies the determination of the magnetometer’s reference vector which always needs systematic calibration or iterative estimation in existing methods. We name the proposed method the Fast Accelerometer-Magnetometer Fusion (FAMF). Our proposed method has the advantages of better computation accuracy and less time consumption. Several experiments are carried out to illustrate the attitude determination results. Besides, comparisons with existing representative methods are also presented in the experimental section of this paper, which verify the effectiveness of the proposed FAMF. Finally, we experimentally show that the FAMF’s roll and pitch angles are immune to magnetic distortion, which ensures the robustness under complex environments for micro air vehicles (MAV).

Owing to the enlarged exciton binding energy and the ability to confine charge carriers compared to their three-dimensional (3D) counterparts, research on quasi-two-dimensional (quasi-2D) perovskite materials and the correlative application in light-emitting diodes (LEDs) has attracted considerable attention. However, high density of defects, exciton emission trapping, and unbalanced charge injection are still the main intractable obstacles to their further development and practical application. Herein, we report an efficient multifunctional interlayer, lithium fluoride (LiF), to boost the performance of green-emitting quasi-2D perovskite LEDs (PeLEDs) by simultaneously overcoming the aforementioned issues. The introduced LiF interlayer not only eliminates the defects at perovskite grain boundaries and the surface by reinforcing the chemical bonds with uncoordinated lead ions but also restrains the emission of perovskite from quenching triggered by the electron transport layer and reduces excess electron injections to effectively balance carriers in the device. As a result, the resulting green quasi-2D PeLED shows a maximum external quantum efficiency of 16.35%, which is the best value obtained for quasi-2D perovskite-based LEDs reported so far, with simultaneous improvement in the operating lifetime of the device.

Reported herein is a palladium/copper cooperative-catalyzed dicarbofunctionalization of alkene-tethered carbamoyl chlorides with 1,1-diborylmethane. This cyclization/deborylation cascade strategy allows for the expedient formation of the versatile borylated 3,3-disubstituted oxindole skeleton, allowing for further functionalization via the derivatization of the carbon–boron bond.

We report herein a miscellaneous oxindole synthesis bearing an all-carbon quaternary center, enabled by Pd-catalyzed intramolecular cyclization followed by multiple intermolecular Heck reactions of both easily accessible alkene-tethered carbamoyl chlorides and olefins. This protocol obviates the use of prefunctionalized olefinic reagents, exhibits excellent functional group tolerance, and features fascinating reactive versatility.

Al2O3binders of various particle sizes were used to formulate a zeolite Y-based catalyst, and the acidity of catalysts increases with decreasing Al2O3particle size. Characterization results showed that the amount and location of Al migration are related to the Al2O3particle size, thus influencing the catalysts’ acidity and activity. In the proposed Al2O3–zeolites interaction scheme, the contact area increases with the decreasing Al2O3particle size, which would increase the possibility of Al migration. Compared with microscale Al2O3, nanoscale Al2O3particle is more likely to migrate to zeolites due to its great diffusivity into the zeolite. Catalysts formulated by nanoscale Al2O3have better alkylation performance than those formulated by microscale Al2O3because of their higher acidity. The research on zeolites–binder interaction would give inspirations to zeolite-based catalysts design and industrial application.

This paper applies variational Bayesian to the stochastic system filtering problem for arbitrary measurement disturbances. Considering the system's robustness when confronted with disturbances, we model its dynamics with a random walk model. Afterward, by assuming an inverse-Gamma distribution, the newly introduced covariance is estimated under a variational Bayesian (VB) framework. The proposed filter improves robustness against additive disturbance and degrades automatically into a Kalman filter when without disturbance. Moreover, this filter avoids the labor-intensive process of tuning parameters. A numerical simulation and an on-site vehicle navigation experiment are given to illustrate the effectiveness of the proposed filter. [ABSTRACT FROM AUTHOR]

Pt/Y catalysts were made by vacuum impregnation using Pt(NH3)4Cl2, Pt(NH3)4(NO3)2, Pt(NH3)4(CH3COO)2, and Pt(NH3)(NO2) as precursors. The effects of Pt precursors on the performance of Pt/Y catalysts on the physicochemical characteristics and catalytic performance were investigated. The results of X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), NH3-TPD, and Py-IR revealed that the type of platinum salt precursor had no significant effect on the fundamental physicochemical properties of the zeolite catalysts throughout the loading process, including the unit cell, relative crystallinity, specific surface area, pore volume, and acid properties. Also, the lifetime of alkylation of the supported catalysts remains the same compared with the one before Pt loading. However, the regeneration performance differs obviously; when the Pt loading was reduced to 0.3%, the catalyst (Pt–N–Y) prepared with Pt(NH3)4(NO3)2as the precursor showed the best stable regeneration capability due to the highest Pt dispersion of Pt–N–Y according to transmission electron microscopy (TEM), thermogravimetric and mass-spectrometric (TG-MS) analyses, and H2-TPR analysis. In addition, the reason for this has been discussed in detail. The decomposition temperature of the Pt(NH3)4(NO3)2precursor is only 240 °C, and the reduction temperature of the catalyst prepared by it is also lower, which avoids the agglomeration of Pt particles at high temperatures. At the same time, the one-step decomposition of Pt(NH3)4(NO3)2reduced the degree of autoreduction of POxby NH3. Thus, with a lower Pt loading, Pt–N–Y exhibits steady reaction-regeneration performance in isobutane-butene alkylation.

The soft-hard interbedded rocks are often encountered in rock engineering such as mining engineering, tunnel engineering, and natural gas engineering. In this study, the horizontal soft-hard interbedded composite rock-like material (HSHC) specimens were prepared with different thickness ratios of rock-like layers, and a series of uniaxial compression tests were performed by using a self-designed loading mold. A parameter Rwas defined for the HSHC specimens, which is related to the thickness ratio of the soft and hard rock-like layers, the length-width ratio, and the mechanical parameters of the soft and hard rock-like materials. Rwas regarded to characterize the strength properties of the HSHC specimens. The test results showed that the axial strength of the HSHC specimens decreases first and then tends to be constant with increasing of R. Digital image correlation (DIC) technique was used to investigate the strain evolution and crack propagation process of the HSHC specimens. The displacement variation trend of the specimen can be roughly divided into three stages: stable deformation stage, rapid crack growth stage and instability failure stage. The failure mode of the HSHC specimens was mainly splitting tensile failure along the bedding plane. Meanwhile, a simplified mechanical model of laminated rock mass under uniaxial compression is established. The strength variation trend predicted by this model is consistent with the experimental results. The present study can reveal the failure mechanism of soft-hard interbedded rock mass at the bottom of the tunnel under the action of large horizontal stress after excavation.

AbstractTo improve the processability and toughness of bisbenzoxazine, a series of cardanol-based aromatic diamine benzoxazine (BZ-Xc) monomers were synthesized from cardanol, formaldehyde aqueous solution and aromatic diamines with different bridging groups such as -CH2-, -O- and -SO2-. The curing behavior, viscosity, thermal and mechanical properties of 4,4′-diaminodiphenylmethane (DDM)-based bisbenzoxazine (BM) and BZ-Xc copolymers were studied systematically. The results demonstrate that the plasticizing effect and flexibility of the alkyl side chain on BZ-Xc significantly reduced the melting viscosity of BM/BZ-Xc blends and improved the toughness of the copolymers. At the same time, the heat-resistant and mechanical properties of the copolymers were retained, because of the bifunctional structure of BZ-Xc. Moreover, the melting viscosity, glass transition temperature and curing temperature of the corresponding copolymers were increased as the result of rigidity and electron-withdrawing effects of the -SO2- bridging group compared to others.

Our objective was to trace and evaluate intracoronary transplanted mesenchymal stem cells (MSCs) labelled with superparamagnetic iron oxide (SPIO) by using magnetic resonance imaging (MRI) in a swine model of myocardial infarction (MI).

Objective— Vascular endothelial growth factor (VEGF), angiopoietin (Ang)-1 and -2 regulate angiogenesis and might be important in myocardial collateral development. Elevated levels of angiogenic growth factors in patients with coronary artery disease (CAD) have been reported. However, the age-related change of angiogenic growth factors in patients with CAD remains unclear.Methods and results— Serum VEGF, Ang-1 and -2 levels were measured by enzyme-linked immunosorbent assay kits. Serum VEGF, Ang-1 and -2 levels in patients with CAD were significantly higher than those in healthy control subjects. In patients aged < 61 years and 61 to 70 years, serum Ang-1 and -2 levels were significantly higher than in patients aged > 70 years, serum Ang-2 levels in patients aged < 61 years were significantly higher than in patients aged from 61 to 70 years. Serum VEGF levels were not significantly different in the three age groups. Serum VEGF, Ang-1 and -2 levels were not significantly different across the age groups in healthy subjects. Regression analysis showed that there was a negative correlation between age and Ang-1 and -2 in patients with CAD.Conclusion— Serum Ang-1 and -2 levels, but not VEGF levels in patients with CAD, are decreased along with advancing age.

Perovskite solar cells (PSCs) have been rapidly crowded into the emerging photovoltaic technology, exhibiting continuously boosted power conversion efficiencies (PCEs) over 25%. Despite the high PCE, the voltage loss (Vloss) of PSCs still need to be further reduced to achieve higher open-circuit voltage (Voc) and thus approaching its Shockley–Queisser limit. Great effort on minimizing the Vlosshas been made by mainly suppressing non-radiative recombination in perovskite and/or relevant interface, maximizing initial radiative efficiency, and modifying energy level alignment in PSCs. However, a timely overview of the lowest Vlossvalues achieved and the strategies of suppressing Vlossfor the PSCs based on the most prevalent perovskite compositions is still lacking. In this review, the definition and determining factors of Vlossare elucidated, and the state-of-the-art low Vlossvalues of PSCs based on various types of prevailing perovskites with variable bandgaps are comprehensively discussed. The strategies for suppressing Vlossof PSCs are highlighted, aiming to boost the fundamental understanding of related Vlossmechanisms. Finally, an insightful perspective on further suppressing the Vlossin PSCs is provided, targeting on achieving new record PCEs in PSCs.

The efficiency and stability of perovskite solar cells (PSCs) are hampered by the undesirable charge recombination on defective surface of polycrystalline perovskite grains and inferior charge transfer at relevant contact interfaces. Herein, we discovered that spontaneous anchoring of long-chain oleylamine (OA) ligands onto perovskite film surface can simultaneously improve the efficiency and stability of PSCs made by scalable blade-coating. The ultrathin insulating OA layer on perovskite film surface can achieve an ingenious surface/interface functionalization that plays synergistic roles in effective defect passivation and efficient charge tunneling. Blade-coated PSCs with OA functionalization acquire champion power conversion efficiencies (PCEs) of 21.5%, accompanied by a surprisingly high fill factor up to 86.3%, which can be ascribed to the reduced series resistance, facilitated electron tunneling and suppressed interfacial charge recombination at relevant interface. The OA-functionalized perovskite film is much more resistant to moisture, and improves the device shelf lifetime to >1000 h, and operation stability to >500 h under continuous one sun illumination with 96% initial efficiency retained.