Aseptic loosening caused by the wear and tear of the artificial joint prosthesis after implantation is one of the main causes of artificial joint failure. Therefore, it is important to investigate the wear debris generated due to wear when developing new artificial joint materials. Aseptic loosening is related to the size, number, and morphology of wear debris, and this study proposed the separation and extraction of mixed wear debris with different density ratios of artificial joints by centrifugation to study the characteristics of different artificial joint wear and wear debris extraction rates. The results showed that multiple centrifugations to separate the mixed wear debris were able to reintroduce the wear debris on the wall of the centrifuge tube into the solution and that the wear debris extraction rate was increased. Suspensions with different density ratios of artificially jointed mixed wear debris were effectively separated by this method. The total extraction rate of the three repeated extractions compared to the first extraction rate, the extraction rate of CoCrMo wear debris increased by 6.7%, ultra-high molecular weight polyethylene (UHMWPE) wear debris increased by 15.1–23.44%, ZrO2wear debris increased by 10.91%, and that of polyether ether ketone (PEEK) wear debris increased by 9.95%. This method for separating and extracting wear debris from artificial joints can realize the separation of mixed wear debris from artificial joints and obtain a high extraction rate and high-quality wear debris images, investigate the wear mechanism of artificial joint implants, and provide valuable information on the wear performance of new artificial joint implants under investigation.Keywords:different density ratios;multiple centrifugal separations;wear chips
Xiaoming Luo,Juhang Cao,Jing Ren,Haipeng Yan,Limin He
The suspension characteristics of water droplet in oil were investigated under ultrasonic standing waves with high-speed photography in this paper. Firstly, the suspension position of droplet was predicted by theoretical derivation. The motion trajectory of droplet was captured and a kinetic analysis was applied to characterize the suspension position of droplet. The effects of droplet size, acoustic pressure, frequency, as well as density ratio of water and oil on the suspension position of droplet were analyzed in details. It was proved that the droplet size had little effect on the suspension position at different frequencies. The suspension zone approached minimum at 39.4 kHz, and the suspension position of droplet was insensitive to acoustic pressure amplitude and density ratio at this frequency. These would be advantageous to maintain the stability of droplet banding and shorten the width of banding. In addition, it was proved that the suspension position of droplet is approximately linear with the density ratio at different frequencies.
Graphical Alternative hypergolic fuels : A family of novel azide-functionalized cation-based hypergolic ionic liquids were designed and synthesized from cost-effective materials. These ionic liquids displayed excellent properties including low melting points, high thermal stability, low viscosities, and unique hypergolic reactivity, demonstrating their promise as potential alternative hypergolic fuels to toxic and volatile hydrazine derivatives. Hypergolic ionic liquids (ILs) have shown a great promise as viable replacements for toxic and volatile hydrazine derivatives used as propellant fuels, and hence, have attracted increasing interest over the last decade. To take advantage of the reactivity and high energy density of the azido group, a family of low-cost and easily prepared azide-functionalized cation-based ILs, including fuel-rich anions, such as nitrate, dicyanamide, and nitrocyanamide anions, were synthesized and characterized. All the dicyanamide- and nitrocyanamide-based ILs exhibited spontaneous combustion upon contact with 100 % HNO 3 . The densities of these hypergolic ILs varied in the range 1.11–1.29 g cm −3 , and the density-specific impulse, predicted based on Gaussian 09 calculations, was between 289.9 and 344.9 s g cm −3 . The values of these two key physical properties are much higher than those of unsymmetrical dimethylhydrazine (UDMH). Among the studied compounds, compound IL-3b, that is, 1-(2-azidoethyl)-1-methylpyrrolidin-1-ium dicyanamide, shows excellent integrated properties including the lowest viscosity (30.9 M Pa s), wide liquid operating range (−70 to 205 °C), shortest ignition-delay time (7 ms) with 100 % HNO 3 , and superior density specific impulse (302.5 s g cm −3 ), suggesting promising applications with potential as bipropellant formulations.
危险品化学品经营许可证（带存储）