Showing papers by "University of Macau published in 2022"

Surface Passivation Using 2D Perovskites toward Efficient and Stable Perovskite Solar Cells

Abstract: 3D perovskite solar cells (PSCs) have shown great promise for use in next-generation photovoltaic devices. However, some challenges need to be addressed before their commercial production, such as enormous defects formed on the surface, which result in severe SRH recombination, and inadequate material interplay between the composition, leading to thermal-, moisture-, and light-induced degradation. 2D perovskites, in which the organic layer functions as a protective barrier to block the erosion of moisture or ions, have recently emerged and attracted increasing attention because they exhibit significant robustness. Inspired by this, surface passivation by employing 2D perovskites deposited on the top of 3D counterparts has triggered a new wave of research to simultaneously achieve higher efficiency and stability. Herein, we exploited a vast amount of literature to comprehensively summarize the recent progress on 2D/3D heterostructure PSCs using surface passivation. The review begins with an introduction of the crystal structure, followed by the advantages of the combination of 2D and 3D perovskites. Then, the surface passivation strategies, optoelectronic properties, enhanced stability, and photovoltaic performance of 2D/3D PSCs are systematically discussed. Finally, the perspectives of passivation techniques using 2D perovskites to offer insight into further improved photovoltaic performance in the future are proposed.

Engineering Radiosensitizer‐Based Metal‐Phenolic Networks Potentiate STING Pathway Activation for Advanced Radiotherapy

Abstract: Radiotherapy, a mainstay of first-line cancer treatment, suffers from its high-dose radiation-induced systemic toxicity and radioresistance caused by the immunosuppressive tumor microenvironment. The synergy between radiosensitization and immunomodulation may overcome these obstacles for advanced radiotherapy. Here, the authors propose a radiosensitization cooperated with stimulator of interferon genes (STING) pathway activation strategy by fabricating a novel lanthanide-doped radiosensitizer-based metal-phenolic network, NaGdF4 :Nd@NaLuF4 @PEG-polyphenol/Mn (DSPM). The amphiphilic PEG-polyphenol successfully coordinates with NaGdF4 :Nd@NaLuF4 (radiosensitizer) and Mn2+ via robust metal-phenolic coordination. After cell internalization, the pH-responsive disassembly of DSPM triggers the release of their payloads, wherein radiosensitizer sensitizes cancer cells to X-ray and Mn2+ promote STING pathway activation. This radiosensitizer-based DSPM remarkably benefits dendritic cell maturation, anticancer therapeutics in primary tumors, accompanied by robust systemic immune therapeutic performance against metastatic tumors. Therefore, a powerful radiosensitization with STING pathway activation mediated immunostimulation strategy is highlighted here to optimize cancer radiotherapy.

Instant diagnosis of gastroscopic biopsy via deep-learned single-shot femtosecond stimulated Raman histology

Abstract: Abstract Gastroscopic biopsy provides the only effective method for gastric cancer diagnosis, but the gold standard histopathology is time-consuming and incompatible with gastroscopy. Conventional stimulated Raman scattering (SRS) microscopy has shown promise in label-free diagnosis on human tissues, yet it requires the tuning of picosecond lasers to achieve chemical specificity at the cost of time and complexity. Here, we demonstrate that single-shot femtosecond SRS (femto-SRS) reaches the maximum speed and sensitivity with preserved chemical resolution by integrating with U-Net. Fresh gastroscopic biopsy is imaged in <60 s, revealing essential histoarchitectural hallmarks perfectly agreed with standard histopathology. Moreover, a diagnostic neural network (CNN) is constructed based on images from 279 patients that predicts gastric cancer with accuracy >96%. We further demonstrate semantic segmentation of intratumor heterogeneity and evaluation of resection margins of endoscopic submucosal dissection (ESD) tissues to simulate rapid and automated intraoperative diagnosis. Our method holds potential for synchronizing gastroscopy and histopathological diagnosis.

Adaptive Backstepping Control of a Quadcopter With Uncertain Vehicle Mass, Moment of Inertia, and Disturbances

Abstract: In this article, we propose a solution to the problem of path following for a quadcopter aircraft with unknown vehicle parameters (mass and moment of inertia) and external disturbances By employing the backstepping technique, the proposed adaptive control strategy guarantees the following: the quadcopter is globally steered toward, and kept within, an arbitrarily small neighborhood of a desired smooth path, achieving global uniformly ultimately boundedness; compared to trajectory tracking, a smoother convergence is obtained as the control actuation signals (thrust force and torque) are bounded with respect to the position error, and the designed timing law ensures that the desired path starts to move only when the vehicle gets close to the desired path; and a single adaptive control law can be used for accurate motion control of aerial vehicles with a wide range of inertial properties, without the need for retuning control gains or other parameters Moreover, the controller is also made robust to external constant and slowly time-varying disturbances through the design of disturbance estimators To demonstrate the effectiveness and performance of the proposed control strategies, simulation and experimental results are presented and analyzed

Design of a new passive end-effector based on constant-force mechanism for robotic polishing

Abstract: Polishing is an important final machining process in manufacturing. For robotic polishing, active compliance control is the most frequently used approach to control the contact force between the end-effector and workpiece. However, it usually exhibits the problem of force overshoot at the start of contact, with poor force accuracy normally larger than 1 N. This paper proposes the concept design of a novel end-effector based on constant-force mechanism for robotic polishing. This design is the first constant-force mechanism based robotic end-effector for use in polishing experiment. An industrial robot is used to position the end-effector and the end-effector regulates the contact force passively. The constant-force motion range acts as a buffer to counteract the excessive displacement caused by inertia. As a result, there is no force overshoot, producing the consistency for the workpiece’s surface quality. Moreover, the property of the constant force ensures more accurate contact force without using a complex controller. Design, modeling, and simulation study have been performed to demonstrate the proposed idea. A prototype is fabricated for experimental testing. The end-effector is adopted to polish rusty steel, and the recorded contact force signal during polishing demonstrates the effectiveness of the constant-force mechanism in counteracting the force overshoot and improving the force accuracy. Results indicate that the polished surface is extremely uniform with steady contact force regulated by the constant-force mechanism.

Lead oxide enables lead volatilization pollution inhibition and phase purity modulation in perovskite quantum dots embedded borosilicate glass

Abstract: Embedding all-inorganic cesium lead halide CsPbX3 (X=Cl, Br, I) perovskite quantum dots (PQDs) PQDs into glass is one of the most effective strategies to improve their optical, thermal and chemical stabilities. Herein, by using PbO instead of PbBr2 as the lead source, it is effective to lower the melting temperature and reduce the volatilization pollution from lead halide raw materials. Thus, a high-purity CsPbBr3 PQDs embedded glass with 71.5 % PLQY was successfully prepared. The thermal stability, and photo-aging properties were also improved. By simply changing the halogen element, the red and blue CsPbX3 PQDs embedded glasses were successfully prepared. The white LED fabricated by coating obtained green/red CsPbX3 PQDs embedded glass on a blue chip displays high color gamut of 121.9 % NTSC standard and >91.1 % Rec. 2020 standard, which embodies the great potential of PQDs embedded glass in lighting and display fields.

Analysis, Design, and Implementation of Multi-Quasi-Proportional-Resonant Controller for Thyristor-Controlled LC -Coupling Hybrid Active Power Filter (TCLC-HAPF)

Abstract: Compared with the conventional active power filter, the thyristor-controlled LC -coupling hybrid active power filter (TC LC -HAPF) has a distinct characteristics of low dc-link operating voltage, which can lower the system and operational costs in the medium-voltage-level system. It also has a wider operational range than the conventional hybrid active power filter. Besides that, the TC LC -HAPF can provide reactive, harmonic, and unbalanced powers compensation simultaneously. In this article, the modeling of the TC LC -HAPF is investigated based on the linear control aspect. Then, the analysis, design, and implementation of a multi-quasi-proportional-resonant (MQPR) controller with gain scheduling for the TC LC -HAPF will be proposed, which can automatically change the resonant gain between the inductive and capacitive loads operation to improve its compensation performances. The proposed controller can significantly reduce the TC LC -HAPF steady-state current tracking errors and output current ripple. Finally, the simulation and experimental results are also provided to verify the effectiveness and performance of the MQPR controller for the TC LC -HAPF in comparison with the hysteresis current controller and quasi-proportional-resonant (QPR) controller, which shows superior compensating performances.

Phrase dependency relational graph attention network for Aspect-based Sentiment Analysis

Abstract: Aspect-based Sentiment Analysis (ABSA) is a subclass of sentiment analysis, which aims to identify the sentiment polarity such as positive, negative, or neutral for specific aspects or attributes that appear in a sentence. Previous studies have focused on extracting aspect-sentiment polarity pairs based on dependency trees, ignoring edge labels and phrase information. In this paper, we instead propose a phrase dependency graph attention network (PD-RGAT) on the ABSA task, which is a relational graph attention network constructed based on the phrase dependency graph, aggregating directed dependency edges and phrase information. We perform experiments with two pre-training models, GloVe and BERT. Experimental results on the benchmarking datasets (i.e., Twitter, Restaurant, and Laptop) demonstrate that our proposed PD-RGAT has comparable effectiveness to a range of state-of-the-art models and further illustrate that the graph convolutional structure based on the phrase dependency graph can capture both syntactic information and short long-range word dependencies. It also shows that incorporating directed edge labels and phrase information can enhance the capture of aspect-sentiment polarities on the ABSA task.

Lead oxide enables lead volatilization pollution inhibition and phase purity modulation in perovskite quantum dots embedded borosilicate glass

Abstract: Embedding all-inorganic cesium lead halide CsPbX3 (X=Cl, Br, I) perovskite quantum dots (PQDs) PQDs into glass is one of the most effective strategies to improve their optical, thermal and chemical stabilities. Herein, by using PbO instead of PbBr2 as the lead source, it is effective to lower the melting temperature and reduce the volatilization pollution from lead halide raw materials. Thus, a high-purity CsPbBr3 PQDs embedded glass with 71.5 % PLQY was successfully prepared. The thermal stability, and photo-aging properties were also improved. By simply changing the halogen element, the red and blue CsPbX3 PQDs embedded glasses were successfully prepared. The white LED fabricated by coating obtained green/red CsPbX3 PQDs embedded glass on a blue chip displays high color gamut of 121.9 % NTSC standard and >91.1 % Rec. 2020 standard, which embodies the great potential of PQDs embedded glass in lighting and display fields.

Revealing pion and kaon structure via generalised parton distributions *

Abstract: Clear windows onto emergent hadron mass (EHM) and modulations thereof by Higgs boson interactions are provided by observable measures of pion and kaon structure, many of which are accessible via generalised parton distributions (GPDs). Beginning with algebraic GPD Ansaetze, constrained entirely by hadron-scale $\pi$ and $K$ valence-parton distribution functions (DFs), in whose forms both EHM and Higgs boson influences are manifest, numerous illustrations are provided. They include the properties of electromagnetic form factors, impact parameter space GPDs, gravitational form factors and associated pressure profiles, and the character and consequences of all-orders evolution. The analyses predict that mass-squared gravitational form factors are stiffer than electromagnetic form factors; reveal that $K$ pressure profiles are tighter than $\pi$ profiles, with both mesons sustaining near-core pressures at magnitudes similar to that expected at the core of neutron stars; deliver parameter-free predictions for $\pi$ and $K$ valence, glue, and sea GPDs at the resolving scale $\zeta=2$GeV; and predict that at this scale the fraction of meson mass-squared carried by glue and sea combined matches that lodged with the valence degrees-of-freedom, with a similar statement holding for mass-squared radii.