We reported a highly efficient electrochemical immunosensor utilizing chitosan–graphene nanosheets (CS-GNs) nanocomposites for the detection of aflatoxin B₁ (AFB₁) in corn samples. The CS-GNs nanocomposites, serving as a modifying layer, provide a significant specific surface area and biocompatibility, thereby enhancing both the electron transfer rate and the efficiency of antibody immobilization. The electrochemical characterization was conducted utilizing both differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). Moreover, the antibody concentration, pH, antibody immobilization time, and immunoreaction time, were optimized. The results showed that the current change ($\Delta I$) before and after the immunoreaction demonstrated a strong linear relationship ($R^2=0.990$) with the AFB₁ concentration, as well as good specificity and stability. The linear range extended from 0.05 to 25 ng/mL, with a detection limit of 0.021 ng/mL ($S/N=3$). The immunosensor exhibited a recovery rate ranging from 97.3% to 101.4% in corn samples, showing a promising performance using an efficient method, and indicating a remarkable prospect for the detection of fungal toxins in grains.

In this study, we developed a low-cost, high-sensitivity chemiluminescence competitive aptamer sensor for the detection of aflatoxin B₁ (AFB₁) in wheat samples. The optical fiber sensor was self-made, and it utilized biotin and streptavidin (SA) link aptamer and horseradish peroxidase (HRP) for the chemiluminescence detection, achieving competitive assay between the AFB₁ and AFB₁ antigen. We adjusted the experimental conditions of the sensor base on the date of optimization of the experimental conditions and chose coated antigens on the surface of carboxyl magnetic particles. Under conditions optimized by testing key parameters, the assay results showed that the chemiluminescence intensity and AFB₁ concentration demonstrated a strong linear relationship (R² = 0.995), the dynamic range was from 0.1 to 10 ng/mL with a detection limit of 0.09 ng/mL, and the aptamer exhibited good specificity and anti-interference ability. Testing the wheat samples showed that the spiked recovery rate ranged from 79.19% to 113.21%. The sensor possesses characteristics of low detection limits, simple manufacturing methods, and affordability, providing a novel solution for the development of low-cost and high-sensitivity AFB₁ detection equipment.

Due to the influences of the storage environment, water content change, particle settlement, natural loss, and other factors, the distribution density of wheat and the volume of grain pile in the storage process are gradually changed so that the single weight calculation method cannot objectively evaluate the storage quantity of wheat and also causes difficulties to the regular inspection of the quantity of wheat stock. To meet the practical needs of wheat inventory monitoring, a wheat inventory monitoring method based on inventory measurement and the support vector machine regression (SVR) prediction model is proposed. By collecting the working papers for the physical inspection of wheat in grain warehouses in Shanxi province, Hebei province, Henan province, Jiangsu province, and other places, the storage time, storage weight, storage moisture content, measured moisture content, measured volume weight, measured net volume, and measured weight for inspection were selected as training samples for the SVR prediction model, and kernel function selection and parameter optimization were carried out. We developed an optimal prediction model for the amount of wheat in the grain depots. In the actual grain store measurement process, the net volume of wheat in the current grain store was obtained by a laser volumetric measuring apparatus, the actual bulk density of wheat was sampled, and the actual moisture content of wheat was measured by sampling. The three samples, their storage time, their storage moisture content, and their storage weight were fed into the trained SVR prediction model as new samples, and the predicted weight of the wheat in the current grain store was obtained from the output. The error rate calculation procedure was introduced to achieve an anomalous judgment error rate for grain depots. The experimental results showed that the SVR prediction model based on the linear kernel function had a very low mean squared error and high determination coefficient, and the average prediction accuracy of the grain stock error rate reached 93.2 percent, which can meet the requirements of wheat quantity monitoring in grain warehouses.

People are gradually coming around to the idea of living a low-carbon lifestyle and using green transportation, and given the severe urban traffic congestion, electric bicycle commuting has taken over as the preferred mode of short-distance transportation for many. Since batteries are used to power electric bicycles, there are no greenhouse gas emissions while they are in use, which is more in line with the requirement for sustainable development around the world. The public has been increasingly concerned about the safety issues brought on by electric bicycles as a result of the industry’s quick development and the rapid increase in the number of electric bicycles worldwide. The unsafe operation of the elevator and the safety of the building have been seriously compromised by the unauthorized admission of electric bicycles into the elevator. To meet the need for fast detection and identification of electric bicycles in elevators, we designed a modified YOLOv5-based identification approach in this study. We propose the use of the EIoU loss function to address the occlusion problem in electric bicycle recognition. By considering the interaction ratio and overlap loss of the target frames, we are able to enhance localization accuracy and reduce the missed detection rate of occluded targets. Additionally, we introduce the CBAM attention mechanism in both the backbone and head of YOLOv5 to improve the expressive power of feature maps. This allows the model to prioritize important regions of the target object, leading to improved detection accuracy. Furthermore, we utilize the CARAFE operator during upsampling instead of the nearest operator in the original model. This enables our model to recover details and side information more accurately, resulting in finer sampling results. The experimental results demonstrate that our improved model achieves an mAP of 86.35 percent, a recall of 81.8 percent, and an accuracy of 88.0 percent. When compared to the original model under the same conditions, our improved YOLOv5 model shows an average detection accuracy increase of 3.49 percent, a recall increase of 5.6 percent, and an accuracy increase of 3.5 percent. Tests in application scenarios demonstrate that after putting the model on the hardware platform Jeston TX2 NX, stable and effective identification of electric bicycles can be accomplished.

In this paper, we propose a grain volume measurement method based on binocular structured light to address the need for fast and high-precision grain volume measurement in grain stocks. Firstly, we utilize speckle structured light imaging to tackle the image matching problem caused by non-uniform illumination in the grain depot environment and the similar texture of the grain pile surface. Secondly, we employ a semi-global stereo matching algorithm with census transformation to obtain disparity maps in grain bins, which are then converted into depth maps using the triangulation principle. Subsequently, each pixel in the depth map is transformed from camera coordinates to world coordinates using the internal and external parameter information of the camera. This allows us to construct 3D cloud data of the grain pile, including the grain warehouse scene. Thirdly, the improved European clustering method is used to achieve the segmentation of the three-dimensional point cloud data of the grain pile and the scene of the grain depot, and the pass-through filtering method is used to eliminate some outliers and poor segmentation points generated by segmentation to obtain more accurate three-dimensional point cloud data of the grain pile. Finally, the improved Delaunay triangulation method was used to construct the optimal topology of the grain surface continuous triangular mesh, and the nodes of the grain surface triangular mesh were projected vertically to the bottom of the grain warehouse to form several irregular triangular prisms; then, the cut and complement method was used to convert these non-plane triangular prisms into regular triangular prisms that could directly calculate the volume. The measured volume of the pile is then obtained by calculating the volume of the triangular prism. The experimental results indicate that the measured volume has a relative error of less than 1.5% and an average relative error of less than 0.5%. By selecting an appropriate threshold, the relative standard deviation can be maintained within 0.6%. The test results obtained from the laboratory test platform meet the requirements for field inspection of the granary.

An electrochemical aptamer sensor for the sensitive detection of aflatoxin B₁ (AFB₁) in corn samples was developed using nanocomposites loaded with copper nanoparticles (CuNPs) on zeolitic imidazolate framework-8 (ZIF-8), which were modified on a glassy carbon electrode (GCE). The CuNPs@ZIF-8 nanocomposites served as modifying materials for electrodes, exhibiting a high specific surface area and excellent compatibility with aptamers, thereby enhancing the electron transfer rate and increasing the aptamer loading and immobilization efficiency. The electrochemical properties before and after modification were investigated and validated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques, while the sensor’s performance was analyzed through quantitative detection via differential pulse voltammetry (DPV). Furthermore, various conditions, including the volume of ZIF-8 dispersion, electrodeposition time of copper nanoparticles, aptamer concentration, and AFB₁ incubation time, were optimized. The results indicated that the sensor exhibited a wide linear range (10.0 to 1.0 × 10⁶ pg/mL), with a lower limit of detection (LOD) of 1.13 pg/mL under optimized conditions, outperforming other reported aptamer sensors. The spiked recoveries in corn samples ranged from 96.663% to 105.72%. In conclusion, this sensor presents a novel solution for low-cost and high-sensitivity detection of AFB₁.