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A 3-RPS parallel leveling mechanism based on the proportional integral (PI) robust sliding mode system is designed to solve the problem of data acquisition inaccuracy caused by vehicle tilting during the robot walking. Firstly, the configuration synthesis is carried out according to the spiral and inverse spiral theory. Then, the dynamic analysis and calculation of the 3-RPS leveling mechanism are carried out to construct its dynamic model. On this basis, the adaptive robust sliding mode algorithm is introduced to optimize and improve the PI controller to improve the stability and adaptive correction ability. The stability of the nonlinear control system is verified by Lyapunov function. Finally, the control error curve is obtained by Matlab/Simulink comparative simulation experiment. The simulation results show that the adaptive correction effect of the PI control system optimized by the robust sliding mode algorithm is remarkable, and the steady-state error of the control is greatly reduced. The research provides a basis for the development of physical prototype of 3-RPS parallel leveling mechanism.

Although scholars have proposed many types of self-assessment methods. There are still many teachers in China who consider that student self-assessment is "difficult to implement". This paper aims to optimize the assessment of MOOC learning, and to establish an integrated student self-assessment paradigm with "student-centered, teacher, and peer auxiliary". We started by selecting nine key factors that influence the implementation of self-assessment in MOOCs. Then, we clarified the relationship between the nine factors by using the interpretative structure model (ISM) and the MICMAC analysis, and a six-level paradigm of integrated student self-assessment was established. Moreover, we put forward the following suggestions to optimize student self-assessment in MOOC learning. First, it's necessary to consider student self-assessment in MOOCs as a formative assessment method. Second, universities should enhance student awareness of self-assessment through publicity. Third, institutions of higher education could set up assessment courses to enhance the quality of assessment of students. Fourth, schools should optimize the environment of student self-assessment with the help of technology. This study is of great significance for students to make self-assessment become the basis of online learning and thus perfect the research on MOOC learning.

The small and medium-sized enterprises provide much economic dynamism for macroeconomic development in China. However, many small and medium-sized enterprises have to face financing difficulties due to external factors and internal factors, such as the willingness of financial institutions to lend and the low credit of small and medium-sized enterprises. The establishment of private banks plays a very important role in alleviating the financing difficulties of small and medium-sized enterprises and eliminating financial suppression. This paper takes the listed small and medium-sized enterprises as samples to study the impact of the development of private banks on the small and medium-sized enterprises financing. The conclusions show that the development of private banks can alleviate the financing difficulties of small and medium-sized enterprises.

Despite significant advances in perovskite solar cells (PeSCs), the operational instability and susceptibility to Pb leakage of PeSCs severely limit their widespread application. To address these issues, this study investigates the effect of doping the Spiro‐OMeTAD hole‐transporting layer (HTL) with a chemically‐modified 2D conjugated covalent organic framework (Tp‐Azo‐COF) on the photovoltaic performance and stability of PeSCs. Enriched with abundant carbonyl (C═O) groups and azo (N═N) nodes, Tp‐Azo‐COF has excellent chelation and adsorption capabilities, and experimental results confirm that Tp‐Azo‐COF effectively decreases Pb leakage and Li‐ion migration, improving the environmental safety and operational stability of PeSCs. The optimized PeSCs (0.12 cm2) exhibit an efficiency of 24.25%, a new benchmark for COF‐modified devices, and maintain robust performance in large‐area modules (18 cm2) with an efficiency of 21.96%. Under accelerated aging tests, including continuous light irradiation at maximum power point tracking for 980 h, the module demonstrated exceptional durability, with near‐100% efficiency retention. The COF doping strategy developed in this study significantly enhances operational stability and minimizes Pb leakage in PeSCs, paving the way for the sustainable, large‐scale deployment of perovskite photovoltaics. [ABSTRACT FROM AUTHOR]

Charge transport layers are critical components in perovskite solar cells (PSCs) for achieving satisfied power conversion efficiencies (PCEs) and device stability. However, these layers often bring incompatible interfaces and complex fabrication, limiting the stability and scalability of PSC technology. Here an alternative strategy of salt‐based catalyzer (SBC) is proposed to regulate the heterogeneous nucleation of perovskite, which enables uniform and well‐controlled perovskite coverage directly onto the salt‐treated substrate without electron transport layers (ETLs). By carefully adjusting the cations, anions, and the thickness of SBC, high‐quality perovskite films along with superior buried interfaces suppress the carrier recombination losses and strengthen the interfacial stability, promoting the resultant device to achieve a record PCE of 23.04%, which represents the highest reported efficiency for ETL‐free PSCs. Meanwhile, the SBC technique can be well extended to large‐area, flexible, and module‐based devices. More encouragingly, the SBC‐based unencapsulated devices exhibit remarkable operational stability by retaining over 90% of initial efficiency for 1540 h under illumination and for 6312 h in an air environment. This work provides an advisable way to fabricate efficient and stable ETL‐free PSCs toward reliable and cost‐effective production. [ABSTRACT FROM AUTHOR]

Plasmonic metal/semiconductor heterostructures show promise for visible-light-driven photocatalysis. Gold nanorods (AuNRs) semi-coated with TiO2 are expected to be ideally structured systems for hydrogen evolution. Synthesizing such structures by wet-chemistry methods, however, has proved challenging. Here we report the bottom-up synthesis of AuNR/TiO2 nanodumbbells (NDs) with spatially separated Au/TiO2 regions, whose structures are governed by the NRs' diameter, and the higher curvature and lower density of CnTAB surfactant at the NRs' tips than on their lateral surfaces, as well as the morphology's dependence on concentration, and alkyl chain length of CnTAB. The NDs show plasmon-enhanced H2 evolution under visible and near-infrared light.

Owing to its high thermal and electrical conductivities, its ductility and its overall non-toxicity.sup.1-3, copper is widely used in daily applications and in industry, particularly in anti-oxidation technologies. However, many widespread anti-oxidation techniques, such as alloying and electroplating.sup.1,2, often degrade some physical properties (for example, thermal and electrical conductivities and colour) and introduce harmful elements such as chromium and nickel. Although efforts have been made to develop surface passivation technologies using organic molecules, inorganic materials or carbon-based materials as oxidation inhibitors.sup.4-12, their large-scale application has had limited success. We have previously reported the solvothermal synthesis of highly air-stable copper nanosheets using formate as a reducing agent.sup.13. Here we report that a solvothermal treatment of copper in the presence of sodium formate leads to crystallographic reconstruction of the copper surface and formation of an ultrathin surface coordination layer. We reveal that the surface modification does not affect the electrical or thermal conductivities of the bulk copper, but introduces high oxidation resistance in air, salt spray and alkaline conditions. We also develop a rapid room-temperature electrochemical synthesis protocol, with the resulting materials demonstrating similarly strong passivation performance. We further improve the oxidation resistance of the copper surfaces by introducing alkanethiol ligands to coordinate with steps or defect sites that are not protected by the passivation layer. We demonstrate that the mild treatment conditions make this technology applicable to the preparation of air-stable copper materials in different forms, including foils, nanowires, nanoparticles and bulk pastes. We expect that the technology developed in this work will help to expand the industrial applications of copper. High oxidation resistance, without degradation of thermal or electrical conductivity, is achieved in copper using surface modification by a solvothermal or electrochemical treatment with sodium formate and formation of a thin surface coordination layer., Author(s): Jian Peng [sup.1] , Bili Chen [sup.1] , Zhichang Wang [sup.1] [sup.2] [sup.3] , Jing Guo [sup.4] , Binghui Wu [sup.1] , Shuqiang Hao [sup.1] , Qinghua Zhang [sup.5] [...]

We have developed a facile procedure that can create asymmetrical building blocks by uniformly deforming nanospheres into C(∞v) symmetry at low cost and high quality. Concave polystyrene@carbon (PS@C) core-shell nanospheres were produced by a very simple microwave-assisted alcohol thermal treatment of spherical PS@C nanoparticles. The dimensions and ratio of the concave part can be precisely controlled by temperature and solvents. The concavity is created by varying the alcohol-thermal treatment to tune the swelling properties that lead to the mechanical deformation of the PS@C core-shell structure. The driving force is attributed to the significant volume increase that occurs upon polystyrene core swelling with the incorporation of solvent. We propose a mechanism adapted from published models for the depression of soft capsules. An extrapolation from this model predicts that the rigid shell is used to generate a cavity in the unbuckled shell, which is experimentally confirmed. This swelling and deformation route is flexible and should be applicable to other polymeric nanoparticles to produce asymmetrical nanoparticles.