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To understand the quantile regression model, research on a statistical analysis of advanced mathematics teaching quality evaluation was proposed. In the research, based on the test bank and questionnaires, statistical analysis was applied to examine the quality of the test bank and investigate the factors affecting the teaching quality, to understand the students’ scores, find the main factors affecting the teaching quality and use them to analyze the students’ learning status and learning quality. This will help teachers understand and grasp the students’ learning process and improve their teaching ability. And it can provide a theoretical basis for qualitative and quantitative analysis to further improve the high quality.

Magnetic two-dimensional (2D) materials have garnered significant attention due to their unique electronic, magnetic, and optical properties and their potential applications in next-generation electronic and optoelectronic devices. However, the magneto-optical effects of oligolayer antiferromagnetic materials remain inadequately understood. Here, we investigate the magnetic properties of few-layer nickel phosphorus trisulfide (NiPS3) and its twisted heterostructures, emphasizing the observation of optical phenomena at low temperatures (1.65 K). By stacking few-layer NiPS3 to fabricate twisted homostructures, we probe their magnetic characteristics using photoluminescence (PL) spectroscopy. Our results reveal that sharp exciton peaks emerge at low temperatures and that the spin chain orientation in oligolayer NiPS3 can be discerned through the polarization dependence of exciton PL intensity. Notably, fewer-layered NiPS3 exhibits a significant magneto-optical effect under an applied magnetic field, allowing the modulation of the polarization angle of its exciton PL spectrum. Additionally, the polarization-dependent Raman spectrum of NiPS3 shows substantial changes under the influence of a magnetic field. These findings underscore the potential of few-layer NiPS3 for future magneto-optical device applications. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) transition metal dichalcogenides (TMDs) have garnered considerable attention for their promising applications in sensors and optoelectronic devices, owing to their exceptional optical, electronic, and optoelectronic properties. However, the inherent high symmetry of TMD lattices imposes limitations on their functional versatility. Here, we present a strategy to disrupt the C3 rotational symmetry of monolayer WSe2 by fabricating a heterostructure incorporating WSe2 and SiP flakes. Through comprehensive experimental investigations and first-principle calculations, we elucidate that in the WSe2/SiP heterostructure, excitons—both neutral and charged—emanating from WSe2 exhibit pronounced anisotropy, which remains robust against temperature variations. Notably, we observe an anisotropic ratio reaching up to 1.5, indicating a substantial degree of anisotropy. Furthermore, we demonstrate the tunability of exciton anisotropy through the application of a magnetic field, resulting in a significant reduction in the anisotropic ratio with increasing field strength, from 1.57 to 1.18. Remarkably, the change in heterojunction anisotropy ratio reaches 24.8% as the magnetic field increases. Our findings elucidate that the perturbation of the C3 rotational symmetry of the WSe2 monolayer arises from a non-uniform charge density distribution within the layer, exhibiting mirror symmetry. These results underscore the potential of heterostructure engineering in tailoring the properties of isotropic materials and provide a promising avenue for advancing the application of anisotropic devices across various fields. [ABSTRACT FROM AUTHOR]

Introduction: This study investigates the characteristics of sediment disturbance caused by impeller rotation in reservoirs of inland rivers with high sediment content in China. A scaled experimental model, reflecting typical environmental conditions of inland water reservoirs in Northwest China, was established in Lanzhou, Gansu Province, following the principle of similarity. Methods: The study integrates numerical simulations using Ansys Fluent software and corroborates the findings through hydraulic experiments. Computational Fluid Dynamics (CFD) and the κ-ε Realizable model were employed to simulate the solid-liquid mixing process, which was verified against the experimental model. Results: The results indicate that increasing the impeller velocity from 2 rad/s to 8 rad/s, while submerged at a depth of 1000 mm in the flow field, enhances the rate of bottom sediment suspension. Furthermore, the rate of suspended sediment discharge from the model outlet increased with inflow velocity ranging from 0.1 m/s to 0.8 m/s. A decrease in the impeller's submersion depth from 600 mm to 1200 mm was found to reduce the maximum disturbance radius affecting the bottom sediment. Discussion: The reliability of the simulation was confirmed by comparing the software results with experimental data. This study provides insights into the mechanisms of sediment-laden flow disturbance in the reservoir areas of inland rivers in China and lays the groundwork for more comprehensive investigations into sediment discharge in these environments. [ABSTRACT FROM AUTHOR]

In view of the complex structure, difficult flotation and difficult leaching of low-grade mixed tungsten and molybdenum ore of a domestic company, the synergistic leaching of molybdenum and tungsten from molybdenum tungsten ore by hydrochloric acid pretreatment--pyrolusite + sulf uric acid was studied. The effects of various factors on the leaching rate of tungsten and molybdenum were investigated. The results show that under the conditions of hydrochloric acid concentration of 1.5 mol/L, liquid volume to solid mass ratio of 6.5/1 and atmospheric pressure, the tungsten and molybdenum ores are pretreated with hydrochloric acid. Under the optimal conditions of filter slag of 20 g, particle size of 200 mesh, pyrolusite dosage of 4 g, sulfuric acid of 8 mol/L, liquid volume to solid mass ratio of 5/1, temperature of 90 °C and leaching time of 3 h, the leaching rates of molybdenum and tungsten are 83% and 73%, respectively. [ABSTRACT FROM AUTHOR]

Blood-contact devices are prone to inflammation, endothelial dysfunction, coagulation, and the uncontrolled release of metal ions during implantation and service. Therefore, it is essential to make these multifunctional. Herein, a superhydrophobic DE@ZnS-ZnO@SA film (composed of dabigatran ester, zinc sulfite, zinc oxide, and stearic acid, respectively) is produced. The prepared film has non-adhesion and antibacterial properties, superior mechanical stability, durability, corrosion resistance, and is self-cleaning and blood-repellent. The results of the hemolysis, cytotoxicity, and other anticoagulant experiments revealed that the film had good blood compatibility, no cytotoxicity, and excellent anticoagulant properties. The film displays anticoagulant properties even after being immersed in Phosphate-Buffered Saline (PBS) for 7 days. Furthermore, the film can spontaneously release H2S gas for 90 h after soaking in an acidic environment (pH = 6) for 90 h. This property improves the acidic microenvironment of the lesion and promotes the proliferation of endothelial cells by using H2S gas. In addition, the film can inhibit the uncontrollable release of Zn2+ ions, avoiding its toxicity even when immersed in an acid environment for 35 days. This time-sequential functionalized surface has the potential to typify the future of blood-contacting scaffolds for long-lasting use. [ABSTRACT FROM AUTHOR]

Exploring the impact of different monitoring angles from unmanned aerial vehicle (UAV) on the monitoring accuracy of soil moisture content (SMC) is crucial for precision irrigation. To this end, experiment was conducted to monitor the SMC of winter wheat at different growth stages under different irrigation treatments in Yangling, Shaanxi, China. At a solar zenith angle of 45°, multispectral remote sensing data from a UAV were collected at thirteen different monitoring zenith angles. Simultaneously, the SMC in the wheat root zone was measured. From the UAV multispectral images, spectral reflectance was extracted for the construction of vegetation indices. Then the correlation between the vegetation indices and the measured SMC was analyzed. With the vegetation indices as input variables, SMC monitoring models were constructed using Extreme Learning Machine (ELM), Random Forest (RF), and Back Propagation Neural Network (BPNN). The study also examined the effect of specific angles (hotspot and dark spot angles) on the estimation accuracy of the SMC at the nadir angle. The results indicated that different monitoring angles significantly impact the SMC estimation accuracy. Band reflectance and vegetation indices exhibited significant peak values and angular effects at the monitoring zenith angle of 45°. The models achieved the optimal inversion accuracy at the hotspot angle (at a monitoring zenith angle of 45° in the solar principal plane), and the accuracy was ranked as follows: BPNN (R2 = 0.71; RMSE = 1.69) > ELM (R2 = 0.52; RMSE = 1.94) > RF (R2 = 0.48; RMSE = 2.10). By eliminating shadows at the nadir angle through the threshold of dark spot, inversion accuracy similar to the hotspot direction is achieved. This study provides a basis for appropriate selection of UAV flight angles for the monitoring of SMC in the root zone of winter wheat. [ABSTRACT FROM AUTHOR]

The leaf area index (LAI) is a crucial physiological indicator of crop growth. This paper introduces a new spectral index to overcome angle effects in estimating the LAI of crops. This study quantitatively analyzes the relationship between LAI and multi-angle hyperspectral reflectance from the canopy of winter oilseed rape (Brassica napus L.) at various growth stages, nitrogen application levels and coverage methods. The angular stability of 16 traditional vegetation indices (VIs) for monitoring the LAI was tested under nine view zenith angles (VZAs). These multi-angle VIs were input into machine learning models including support vector machine (SVM), eXtreme gradient boosting (XGBoost), and Random Forest (RF) to determine the optimal monitoring strategy. The results indicated that the back-scattering direction outperformed the vertical and forward-scattering direction in terms of monitoring the LAI. In the solar principal plane (SPP), EVI-1 and REP showed angle stability and high accuracy in monitoring the LAI. Nevertheless, this relationship was influenced by experimental conditions and growth stages. Compared with traditional VIs, the observation perspective insensitivity vegetation index (OPIVI) had the highest correlation with the LAI (r = 0.77–0.85). The linear regression model based on single-angle OPIVI was most accurate at −15° (R2 = 0.71). The LAI monitoring achieved using a multi-angle OPIVI-RF model had the higher accuracy, with an R2 of 0.77 and with a root mean square error (RMSE) of 0.38 cm2·cm−2. This study provides valuable insights for selecting VIs that overcome the angle effect in future drone and satellite applications. [ABSTRACT FROM AUTHOR]

Drip fertigation (DF) is a widely used technology to increase grain yield with water and fertilizer conservation. However, the mechanism of high grain yield (GY) under DF is still unclear. Here, a four-year field experiment assessed the impacts of four treatments (i.e., conventional irrigation and nitrogen application, CK; drip irrigation with conventional nitrogen fertilization, DI; split-nitrogen fertigation with conventional irrigation, SF; and drip fertigation, DF) on maize phenology, leaf photosynthetic rates, grain filling processes, plant biomass, and GY. The results showed that DF significantly increased maize GY by affecting phenology, grain filling traits, aboveground biomass (BIO) accumulation, and translocation. Specifically, DF significantly increased leaf chlorophyll content, which enhanced leaf photosynthetic rates, and together with an increase of leaf area index, promoted BIO accumulation. As a result, the BIO at the silking stage of DF increased by 29.5%, transported biomass increased by 109.2% (1.2 t ha−1), and the accumulation of BIO after silking increased by 23.1% (1.7 t ha−1) compared with CK. Meanwhile, DF prolonged grain filling days, significantly increased the grain weight of 100 kernels, and promoted GY increase. Compared with CK, the four-year averaged GY and BIO increased by 34.3% and 26.8% under DF; a 29.7%, 46.1%, and 24.2% GY increase and a 30.7%, 39.5%, and 29.9% BIO increase were contributed by irrigation, nitrogen, and coupling effects of irrigation and nitrogen, respectively. These results reveal the high yield mechanism of drip-fertigated maize, and are of important significance for promoting the application of drip fertigation. [ABSTRACT FROM AUTHOR]

Continuous time-series spectral data are important for inversion of crop or soil information. UAV remote sensing is usually selected under clear and windless weather conditions, but it is not possible to have such weather every day, which results in the UAV not collecting continuous daily spectral information. To explore this issue, we focused on summer maize with four irrigation levels as the research subject. A UAV platform with a multispectral sensor was used to acquire measured spectra of the maize canopy. The solar zenith angle was calculated and substituted into the Ambrals kernel-driven model to obtain simulated spectral data for the maize canopy, and the time-series UAV spectral data were complemented. Then, four vegetation indices (VIs) were established using simulated and measured spectral data, respectively, and the accuracy of the simulated VIs was evaluated. Finally, the simulated and measured VIs were used to monitor and evaluate variations in soil surface moisture content, respectively, and provide irrigation warning. The results demonstrated that Ambrals kernel-driven model can be used to simulate the reflectance of maize canopy collected by UAV. The simulated reflectance can complement time-series UAV spectral data and be used to establish VIs, among which Structure Intensive Pigment Index (SIPI) was established with the highest accuracy (R = 0.729). The VIs established by simulated reflectance can be used to monitor soil surface moisture content, and the monitoring effect is similar to the measured data (R2 = 0.642, RMSE = 0.42). It can evaluate the soil moisture a few days after irrigation and ensure the continuity and timeliness of soil moisture data, so as to improve the crop irrigation system and carry out irrigation warning. These results have certain reference for the supplementation of time-series spectral data and farmland irrigation using UAV multispectral remote sensing. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) anisotropic materials have garnered significant attention in the realm of anisotropic optoelectronic devices due to their remarkable electrical, optical, thermal, and mechanical properties. While extensive research has delved into the optical and electrical characteristics of these materials, there remains a need for further exploration to identify novel materials and structures capable of fulfilling device requirements under various conditions. Here, we employ heterojunction interface engineering with black phosphorus (BP) to disrupt the C3 rotational symmetry of monolayer WS2. The resulting WS2/BP heterostructure exhibits pronounced anisotropy in exciton emissions, with a measured anisotropic ratio of 1.84 for neutral excitons. Through a comprehensive analysis of magnetic-field-dependent and temperature-evolution photoluminescence spectra, we discern varying trends in the polarization ratio, notably observing a substantial anisotropy ratio of 1.94 at a temperature of 1.6 K and a magnetic field of 9 T. This dynamic behavior is attributed to the susceptibility of the WS2/BP heterostructure interface strain to fluctuations in magnetic fields and temperatures. These findings provide valuable insights into the design of anisotropic optoelectronic devices capable of adaptation to a range of magnetic fields and temperatures, thereby advancing the frontier of material-driven device engineering. [ABSTRACT FROM AUTHOR]