TPN-COF@Fe-MIL-100 was used to construct an aptasensor for detecting tetracycline. A low detection limit of 1.227 fg mL⁻¹ within 0.01–10000 pg mL⁻¹ is deduced. High selectivity, reproducibility, stability, regenerability, and applicability are obtained.

As a high-temperature structural material, Ni₃Al matrix composites are often used to manufacture basic mechanical components that need to be used in high-temperature conditions. To meet the increasing demand for metal matrix composites with an excellent tribological performance over a wide temperature range, Ni₃Al matrix self-lubricating composites containing Sn-Ag-Cu and Ti₃SiC₂ (NST) were synthesized via laser-melting deposition. Dry sliding friction tests of NST against Si₃N₄ ball were undertaken from 20 to 800 °C to investigate the tribological behavior and wear-triggered self-healing properties. The results show that the tribological behaviors of NST are strongly dependent on the testing temperature and self-healing properties. At low and moderate temperatures from 20 to 400 °C, as the Sn-Ag-Cu flows into the cracks and is oxidized during sliding friction, while the cracks on the worn surface are filled with oxides consisting mainly of Al₂O₃, SnO₂ and CuO. At higher temperatures of 600 and 800 °C, the cracks are filled by the principal oxides of Al₂O₃, TiO₂ and SiO₂ due to the partial decomposition and oxidation of Ti₃SiC₂. Compared with other testing temperatures, the recovery ratio relative to the Ni₃Al base alloy of the cracks on the worn surface of NST is the highest at 400 °C, which is about 76.4%. The synergistic action mechanisms of Sn-Ag-Cu and Ti₃SiC₂ on the crack self-healing from 20 to 800 °C play a significant role in forming a stable solid lubricating film, improving the anti-friction and wear resistance of NST. The results provide a solution allowing for metal matrix composites to achieve excellent lubrication stability over a wide temperature range by virtue of the crack self-healing properties.

Partially- and fully-unzipped nitrogen-doped carbon nanotubes (NCNTs) were prepared by unzipping pristine NCNTs and three carbon nanostructures were applied to support Au nanoparticles (AuNPs) to form nanocomposites (Au/NCNTs, Au/PU-NCNTs, and Au/FU-NCNTs). The electrochemical behavior and the electrocatalytic activities of the nanocomposite-modified electrodes were examined. The oxygen functional groups, doped N content, and AuNP loaded concentrations are dependent on the unzipping-degree and then affect the electrochemical response and electrocatalytic performance of the electrodes. Besides, the three nanocomposites were also used for the immobilization of carcinoembryonic antigen (CEA) aptamer strands and applied for the detection of CEA. The Au/FU-NCNTs possess the optimal electrocatalytic activity and biosensing performance for the biomolecules and CEA, which is attributed to the maximum loaded AuNPs, the largest specific surface areas and the most active sites. The Au/FU-NCNT-based electrochemical aptasensor exhibits high sensitivity with a low detection limit of 6.84 pg mL⁻¹ within a broad linear range of CEA concentration from 0.01 to 10 ng mL⁻¹. All of these results indicate that the Au/FU-NCNTs may be a potential support for construction of aptasensors with high electrochemical effect and can be employed in the fields of biosensing or biomedical diagnosis.

To study the influence of the free piston generator structure on its stable operation, this paper chose the combining mathematical and physical methods to build a simulation model to investigate the influence factors. According to the dynamic and thermodynamic equation, the mathematical model of the free piston internal combustion generator system was established. the simulation model was built with the help of MATLAB/Simulink software, and the validity of the model was verified. Based on this, the influences of ignition position and piston group mass on the operation characteristics of free piston generator were investigated. The simulation results show that the factors such as ignition position, piston group mass have significant effects on the compression ratio, cylinder pressure, maximum acceleration, etc. of the free piston generator, which provides a theoretical basis for the stable operation control of the free piston internal combustion generator.

To stabilize the operation of free-piston engine generators (FPEGs), a variable load control strategy is proposed to regulate piston motion. By dynamically adjusting the equivalent load to control the system’s total resistance, the strategy alters the system circuit current, thereby modifying the electromagnetic resistance on the generator rotor and effectively constraining piston movement. However, this control method also impacts the operating characteristics of the FPEG. To investigate these impacts, simulations were conducted by varying key parameters, including piston mass, heat release, ignition position, and valve overlap length. Results indicate that these factors significantly influence the relationship between compression ratio and peak cylinder pressure. In single closed-loop control, controlling one parameter cannot determine another; instead, control objectives must be prioritized based on specific requirements. This study provides theoretical insights for developing closed-loop control strategies to ensure stable FPEG operation.