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Poly (vinyl alcohol) (PVA) hydrogels are considered promising artificial articular cartilage. However, the weak attachment between PVA hydrogels and subchondral bone limit its application in the biomedical field. In this article, we present a new method to improve the mineralization of PVA hydrogels, and fabricate PVA hydrogels with continuously graded hydroxyapatite coating. The surface of the hydrogels was modified by dopamine self-polymerization and alendronate conjugation subsequently. Based on these, we used simulated body fluids to mineralize the hydrogels to mimic calcified cartilage zone. The modified surface of the PVA hydrogels showed excellent mineralization ability with continuously graded hydroxyapatite (HA). As the main component of human bones, HA can be chemically bonded body tissue on the interface, showing great biological activity. With the content of HA increasing, the cell adhesion ability of the hydrogels was enhanced, which helped the hydrogels integrate tightly with subchondral bone. These results demonstrate that the modified hydrogels could be promising substitutes for articular cartilage.

The better appearance of LCD rare earth polishing powder, the better sales. High-performance polishing powder for LCD was synthesized by using NH4HCO3 subsidence method, with rare earth carbonate as starting material. Coloring mechanism of rare earth polishing powder was studied by using TGA, XRD and so on. Color of rare earth polishing powder was quantitative described with the values of L, a, b, R, and chemical composition had a great influence on it. The result showed that Ca, Mg, Zn, Mn, P, Fe, Cu had a great effect on the white color of rare earth polishing powder, and the color had regular changes with chemical composition, calcining temperature, calcining time. The result can control production of rare earth polishing powder based its color, and it has significant practical value to color control of rare earth polishing powder.

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