Effects of intervertebral disc degeneration on biomechanics behavior characteristics of L4-L5 under the vertical load / 生物医学工程学杂志

A geometrical model of L4-L5 lumbar segment was constructed using a three-dimensional graphics software. Four conditions of the degenerated discs, i. e. light degeneration, moderate degeneration, severe degeneration and complete excision degeneration, were simulated with loading situations using finite element method under the condition of appropriate computational accuracy. By applying a vertical load of 378.93 N on L4 vertebral plate, stress nephograms on joint isthmus under four different working conditions were obtained. The results showed that the contacted area of facet joint was influenced by the degree of intervertebral disc degeneration level, which influenced the mises stress on joint isthmus. It was proved that joint isthmus was the important pressure-proof structure of the back of lumbar vertebra, and the stress values and distribution were related to structural stiffness of the back of lumbar vertebra as well as the contact area of facet joint. The conclusion could be the theoretical reference for the analysis of spinal biomechanics and artificial disc replacement as well.

Determination of Aluminium in Water By Be Ryllon Ⅲ Spectrophotometry / 环境与健康杂志

Objective To Study the method for determination of aluminium in water by spectrophotometry of Be ryllon Ⅲ. Methods Be ryllon Ⅲ reacts on aluminium in oppropriate temperature and acidity in water and produces a red complex compound?The red complex compound can be determined by spectrophotometry. Results The optimum reaction temperature was 85 ℃, the optimum reaction time was 5 min, pH of buffer was 6.1, Beer's law was obeyed in the concentration range of 0-0.02 mg/L for aluminium, rates of recovery were 80.0%-96.0% and RSD was 0.70%. Conclusion This method is accurate, simple, sensitive and repeatable.