A fastener assembly for a spinal fixation system that is particularly useful in treatment of pediatric and small-statured patients includes a fastener, an attachment member, and a locking member. The two housing are capable of rotating about one and another. 05 molml; mixing the solution A and the solution B in a volume ratio of 1:, and achieving a mixture; stirring and emulsifying the mixture, until an emulsion C is achieved; removing the organic solvent from the emulsion C, and achieving a deposit; washing the deposit with deionized water, and achieving a colloid; and drying and calcining the colloid, and eventually achieving a mesoporous material. The connector and the number of batteries are electrically connected to the circuit board. When charged with a sorbed nutrient such as phosphate or selenium, they can be used as fertilizer.