Due to their small particle size and large and modifiable surface, nanoparticles have unique advantages compared with other drug carriers. As a research focus in recent years, polyethylene glycol-polylactic acid (PEG-PLA) block copolymer and its end-group derivative nanoparticles can enhance the drug loading of hydrophobic drugs, reduce the burst effect, avoid being engulfed by phagocytes, increase the circulation time of drugs in blood, and improve bioavailability. Additionally, due to their smaller particle size and modified surface, these nanoparticles can accumulate in inflammation or target locations to enhance drug efficacy and reduce toxicity. Recent advances in PEG-PLA block copolymer nanoparticles, including the synthesis of PEG-PLA and the preparation of PEG-PLA nanoparticles, were introduced in this study, in particular the drug release and modifiable characteristics of PEG-PLA nanoparticles and their application in pharmaceutical preparations.

With the improvement of the load and speed of belt conveyor, the dynamic characteristic problem of belt conveyer appears especially outstanding. This paper analyzed the force situation of the conveyer by the discrete dynamics model, divided n viscoelastic properties mass units in advance, then built system analysis dynamics model by vibration mechanics, built modal neutral file of the flexible belt block by means of finite element analysis software, and built the virtual prototype model of the belt conveyor using ADMAS program. It analyzed the effect of stiffness and damping of belt on the starting process by dynamic characteristics simulation method. The simulation results showed that the speed wave period of belt with the smaller stiffness was longer and the peak was bigger, the belt speed easily occurred stronger surge, the transverse vibration of belt conveyor became more violent. With the increasing of stiffness, the belt speed wave peak value decreased. As the same time, the speed surge also decreased when other operation parameters of the belt conveyer system are fixed, with increasing of the damping, the dynamic tension force peak became smaller gradually, it led to decrease of vibration curve peak. Damping coefficient played the important role in decreasing the vibration intensity, the research result offers a new basis for the analysis and study of the dynamic characteristics of belt conveyor.

To avoid the open problems of the leading wheel and get a more rational structure, the paper uses PRO / E and the finite element software to analyze the leading wheel of JKM-3.25/4 multi-rope friction hoist. The results show that in the leading wheel the rib plates between the channel steel and wheel hub are removed or added the same ones will have little effect on the overall force situation, and only affect the stress of the weld bead. To solve the problem of open weld of rib plates, can consider the rib plates to be removed. When the radial angle between support wheel and drum is bigger than 6°, the overall force of the leading wheel is affected seriously. But when the radial angle is 5°, the amplitude of stress fluctuation is the minimum, which can improve the leading wheel working conditions and increase the service life of the leading wheel. Therefore the suggestion is to take the radial angle of 5° when to design the new multi-rope hoist. Study conclusions provide the theoretical supports for the leading wheel of multi-rope friction design and technical renovation.

This paper is about dynamic simulation of the belt conveyor based on ADAMS and PRO/E, and analyzes the influence of the transport distance of the conveyor start-up. As the transport distance of belt conveyor increases, the time of which start-up speed increases from rapidly to slowly prolongs, and the lateral vibration of the belt is more severe. It provides a basis for the selection of start-up time and idler spacing.

The grey relation analysis method of the grey systems theory is combined with the fault tree analysis method of reliability theory, and introduced to the analysis and diagnosis of striking cylinder of piston air-compressor. The various fault pattern occurrence possibilities in fault tree analysis of the striking cylinder of the piston air-compressor are analyzed and judged by calculating importance of the bottom event structure of the fault tree as well as the calculating and sorting of the grey relation degree, which provides theoretical basis for accurately preventing the fault occurrence. Calculation example showed the effectiveness and reliability of this method.