骨折治疗方法与原则的最优化历程

多年来骨折治疗,新旧技术、新旧理论相互融合,相互碰撞,产生了新的理论和方法,使得临床疗效显著提高,现阶段理智的临床医生应该融汇各家之长,多方互补,对每一位骨折患者的治疗都应该按照最优化的原则进行。但是在医疗过程中总存在着如方法选择不当或者错误,过度治疗,医患信任危机,医疗伦理道德的丧失等情况,我们应该用矛盾分析的方法来思考这些问题。     

老年髋部骨折围手术期医疗风险的分析与对策

髋部骨折是老年人的常见病之一,髋部骨折对老年人生命的危害最大。随着人口老龄化,老年髋部骨折发病率呈逐年上升趋势。老年骨质疏松髋部骨折围手术期的医疗风险临床较常见,如何降低老年骨质疏松髋部骨折围手术期的医疗风险,是临床骨科需要解决的问题。分析存在的风险问题,明确各种风险因素,尽可能降低老年髋部围手术期的医疗风险。     

Educational struggles and political community in South Africa

Democracy is often said to rest on some form of deeper argument, some self-understanding amongst people as belonging to a common political community. This paper explores this issue in the situation of South Africa. The policies of Apartheid have left a legacy of a morally fractured society with little by way of a shared moral discourse, and the paper raises the question of whether the concepts of democracy and community which emerged out of educational struggles in South Africa might provide a basis for the development of a shared moral discourse. The answer provided in the paper is that, although such concepts cannot provide the basis for democracy at a national level, they do provide some hints of how schools might contribute to the emergence of a shared moral discourse, and, thus, the starting point for building a unified political community.     

Critical Poisson’s ratio between toughness and brittleness

We have a new understanding on a unified fracture criterion based on two kinds of strain energy density. A definite expression which is a function of Poisson’s ratio to describe a crucial parameter in the unified fracture criterion is derived. The critical value of Poisson’s ratio between brittle and ductile materials can be derived as 2/7 which is verified by experimental data. Besides, the effect of Poisson’s ratio on the fracture loci in stress spaces is studied using unified fracture criterion. It is found that the decrease in Poisson’s ratio increases the asymmetry of fracture loci between tensile stress states and compressive stress states in principal stress spaces and between Lode parameters are 1 and ?1 in deviatoric-stress spaces. In addition, stress triaxiality has a great effect on the fracture behaviour with different Poisson’s ratios.     

Scale-dependent fracture mode in Cu–Ni laminate composites

Fracture behavior of Cu–Ni laminate composites has been investigated by tensile testing. It was found that as the individual layer thickness decreases from 100 to 20 nm, the resultant fracture angle of the Cu–Ni laminate changes from 72° to 50°. Cross-sectional observations reveal that the fracture of the Ni layers transforms from opening to shear mode as the layer thickness decreases while that of the Cu layers keeps shear mode. Competition mechanisms were proposed to understand the variation in fracture mode of the metallic laminate composites associated with length scale.     

Discontinuous cracking of TiN films on a steel substrate induced by an adhesive interlayer

ABSTRACT

The basic mechanisms governing the process of cracking of single-layer brittle films have been extensively explored through both simulations and experiments. However, the role that an adhesive interlayer plays in the cracking of the overlying brittle film remains unclear. By performing three-point bending experiments, we observed that the insertion of a 100?nm thick Ti interlayer changed the cracking behaviour of TiN films from a continuous pattern to a discontinuous pattern. The slight change in the microstructure of the film and the increase in film thickness arising from the addition of the Ti interlayer are unlikely to cause the observed cracking morphology. The combination of the different interface between the Ti and the steel substrate and the fracture of the Ti interlayer are responsible for the transition in the TiN film cracking morphologies.