No abstract

Food safety related to drug residues in food has become a widespread public concern. Small-molecule drug residue analysis often relies on mass spectrometry, thin-layer chromatography, or enzyme-linked immunosorbent assays (ELISA). Some of these techniques have limited sensitivity and accuracy, while others are time-consuming, costly, and rely on specialized equipment that requires skilled operation. Therefore, the development of a sensitive, fast, and easy-to-operate biosensor could provide an accessible alternative to conventional small-molecule analysis. Here, we developed a nanocup array-enhanced metasurface plasmon resonance (MetaSPR) chip coupled with gold nanoparticles (AuNPs) (MSPRAN) to detect small molecules. As sulfamethazine drug residues in poultry eggs may cause health issues, we selected this as a model to evaluate the feasibility of using MSPRAN for small-molecule detection. The MSPRAN biosensor employed competitive immunoassay technology for sulfamethazine detection. The limit of detection was calculated as 73 pg/mL, with sensitivity approximately twice that of previously reported detection methods. Additionally, the recovery rate of the biosensor, tested in egg samples, was similar to that measured using ELISA. Overall, this newly developed MSPRAN biosensor platform for small-molecule detection provides fast and reliable results, facile operation, and is relatively cost-effective for application in food safety testing, environmental monitoring, or clinical diagnostics.

The capacity expansion project of Yahu landfill site in Pingshan New District of Shenzhen City is based on the old landfill site. It will inevitably cause the inhomogeneity of landfill foundation settlement because of the different new landfill height and the complicated geological conditions, and then cause bending deformation of the permeate discharge guide tube. In this article, the method of layer-wise summation is firstly used to calculate the settlement of pipeline foundation. On the basis of the above settlement calculation, the model of multi-braced steel frame is established to analysis the maximum axial tensile stress and bending degree of pipe by displacement method. The research has a good reference value for judging the safe state of the pipeline under uneven settlement of foundation.

The heap of new waste in landfills impose a large additional load on leachate pipelines constructed under existing landfill sites. There is urgent need to address safety problems caused by the new effect that is produced on these pipelines. Based on a modified Spangler model, the deformations of HDPE pipelines of different diameters and different wall thicknesses under garbage load were calculated and compared with design requirements. The calculation results show that the upper load has remarkable effect on the deformation of pipeline ring cross sections, the deflection of pipelines and loop tension stress of pipe walls. This was due to the differences of diameter and wall thickness of different HDPE pipelines which responded differently to the upper load.