激光焊和脉冲氩焊对钛耐腐蚀性的影响

目的：探讨激光焊和脉冲氩孤焊对耐腐蚀性的影响。方法：采用动电位极化技术，分别测定激光焊接及脉冲氩孤焊接TA2和TC4后，材料阳极极化曲线的变化。将焊接后的拉伸试样浸入37℃人工唾液中，90d取出，利用原子吸收能谱和化学分析方法测定人工唾液中的钛离子浓度，同时用万能拉伸实验机测试浸泡后材料的拉伸负荷及屈服负荷。结果：自腐蚀电位的顺序为：激光焊TA2＞激光焊TC4＞脉冲氩孤焊TA2＞脉冲氩弧焊TC4＞TA2＞TC4，极化电阻的顺序为：TA2（激光焊TC4）＞TC4＞激光焊TA2（脉冲氩弧焊TA2）＞脉冲氩弧焊TC4。未焊接的TA2和TC4均测到点蚀电位，激光焊接TC4、脉冲氩（脉冲氩弧焊TA2）＞脉冲氩弧焊TC4。未焊接的TA2和TC4均测到点蚀电位，激光焊接TC4、脉冲氩弧焊接TA2及TC4的极化曲线未测到点蚀电位。激光焊接TA2点蚀电位较高，钝化电流较小。测得的Ti离子浓度均小于0．398μg/cm^2，浸蚀前后材料的拉伸负荷、屈服负荷无明显变化。结论：激光焊和脉冲氩焊焊接后材料在人工唾液中的耐腐蚀性有所增强，激光焊接后耐腐蚀性增加较明显。     

不同温度热氧化处理钛种植体耐腐蚀性能和离子释放速度的体外研究

目的：采用恒电位仪、原子吸收光谱仪，对三组不同温度热氧化钛种植体表面的耐腐蚀性能和钛离子释放速率进行了研究。方法：三组试样的恒电位阳极极化曲线、腐蚀速率、离子释放速度的对比性研究。结果：各组表面均有好的耐腐蚀性能、低的离子释放速度；而且人工氧化组的耐腐蚀性能最好，钛离子释放率最低。以自然氧化组的耐腐蚀性能最差，钛离子释放率最高。结论：人工氧化组表面最稳定。     

The biologic effects of implant materials

The interaction between implant materials and the surrounding biological environment continues to be an area of intense research and clinical interest. This article presents the information presented in a symposium, held during the 36th Annual Meeting of the Orthopaedic Research Society, in which several important issues concerning the biologic effects of implant materials were discussed. These issues included the mechanisms by which implant materials are released to the surrounding tissues and the ways in which these tissues respond to implant materials. The problem of bone loss around cementless implants was discussed as a specific example of a biologic effect resulting in both bone remodelling and endosteal erosion.     

钨丝弹簧圈溶解的实验研究

目的 通过对钨丝弹簧圈栓塞后标本的光镜及电镜观察以证实其在体内的吸收现象以及吸收后血管是否再通。方法 取大耳白兔6只，不分雌雄。在静脉麻醉下暴露一侧颈总动脉，经7号套管针向动脉内置入我国自行研制生产的自由钨丝弹簧圈直至完全栓塞，分别于3个月及6个月取活体标本进行光镜、电镜观察。弹簧圈周围血管壁组织经常规方法固定后进行普通光镜及透射电镜观察，而分离暴露的弹簧圈未经任何固定直接进行扫描电镜观察。结果3和6个月后肉眼下均可见栓塞的血管内无血流通过。扫描电镜下可见钨丝弹簧圈变细，表面粗糙不平。光镜及透射电镜下可见血管壁周围组织内单核吞噬细胞增生并有金属颗粒沉积，弹簧圈两端的动脉已完全失去了血管壁的结构。取含金属颗粒的组织经电感耦连等质子光谱仪(ICP-MS)定性分析证实其主要成分为钨。结论钨丝弹簧圈在体内确实存在吸收现象，但吸收后血管并不一定再通。     

Formation of the cardiac vascular system and ventricular compact wall

The corrosion cast method for scanning electron microscopy, transmission electron microscopy and auto-injection of tracers for light microscopy were used to examine the cardiac coronary development and the forming of the ventricular compact wall to the embryonal sponge-work wall. Our observations suggest that the coronary artery first extends over outer layer, and later over middle and inner layers. As intertrabecular spaces are closed by fusion to each endocardium in the inner layer position, the veins are formed by the remaining expanded sinusoidal intertrabecular spaces. The capillaries of the coronary vessels are then connected to the veins to finally complete the cardiac vascular system.     

The utility of the combination of the corrosion cast method and post mortem MSCT scans

A careful post-mortem investigation is needed to determine the cause of death of patients bearing coronary stents and to describe complications of stent implantation. The main purpose of this study was to combine post mortem methods of CT angiography and corrosion cast preparation for the visualization of coronary stenoses, coronary stents, instent restenosis, and stent occlusion. Injection-corrosion method was combined with post-mortem MSCT angiography to characterize the pathomorphological changes after stent implantation in 6 male cadaver hearts. Multi-slice computed tomography was employed to visualize the coronary artery system. For image post processing, multiplanar reconstructions, maximal intensity projections and three dimensional reconstructions were used. This study was assessing the feasibility of post mortem MSCT for intracoronary stent evaluation. We described a method for characterization of the coronary side branch stenosis caused by stent implantation. Post mortem CT imaging proved to be a feasible and highly reproducible technique for the characterization of pathological changes in the coronary system.     

Electrochemical characterization of three types of Co-Cr based alloys manufactured by casting and selective laser melting according to ISO 10271

ObjectiveTo characterize the effect of elemental composition and manufacturing process on the electrochemical properties of Co-Cr-Mo, Co-Cr-W and Co-Cr-Mo-W alloys.MethodsSix Co-Cr based alloys were included in this study. All alloys are Co-Cr based alloys, classified in three different types according to their elemental composition. The first group has Mo as the third alloying element while the second one has W instead of Mo. The third one has both alloying elements. The groups are further divided by the manufacturing process (casting or Selective Laser Melting(SLM)). All groups were subjected to static immersion, open circuit potential, anodic scan, SEM/EDX analysis, static and cyclic tarnish testing according to ISO 10271 requirements. The ionic release was evaluated by inductively coupled plasma mass spectrometry and the results were statistically analyzed by two way ANOVA and Tukey test (a=0.05).ResultsNo statistical differences were identified for Co-Cr-Mo alloy for all elements and their total ionic release between casting and SLM manufacturing processes, in contrast to significantly lower values for SLM groups for the other two groups. All groups tested demonstrated similar performance in OCP and AS testing while no gross elemental changes before and after AS were identified following EDX analysis. All alloys fulfilled the requirements of tarnish resistanceConclusionsThe ionic release is dependent on alloy type and manufacturing process while all groups were found to fulfill the requirements of international standards for ionic release, corrosion and tarnish resistance and thus an acceptable clinical performance is anticipated.     

Study on corrosion inhibition behavior and adsorption mechanism of novel synthetic surfactants for carbon steel in 1 M HCl solution

The corrosion inhibition behavior and adsorption mechanism of three novel synthetic surfactants in 1 M HCl solution on carbon steel were investigated. The PP results confirmed that all the synthetic surfactants behave as mixed-type inhibitors, while the EIS results validated the existence of a protective layer by the adsorption of inhibitor molecules on the carbon surface. T₃ was observed to offer the highest inhibition efficiency (η_w, 96.28%) at 1 mM by the static weight loss measurements due to two different hydrophobic chains which form a more compact film with the crosswise arrangement. SEM/EDS and XPS results revealed the formation of the surfactants film on the carbon steel surface. Molecular dynamics simulation (MD) was further executed to determine the adsorption mechanism in molecular level insights. In addition, a linear correlation between surface activity (γ) and corrosion inhibition efficiency (η_w) was verified. The adsorption of the prepared surfactants followed the Freundlich isotherm at different concentration ranges. Moreover, the bilayer/multilayer adsorption mechanism was also proposed and confirmed by experimental, adsorption isotherm studies and MD. Hence, both MD simulations and experimental results revealed the analogous inhibition with the order follows: T₃ > T₂ > T₁.     

Evaluation of the corrosion inhibition effect of the combined admixture of rosemary and cinnamon cassia oil on mild steel in weak acid electrolyte

The corrosion resistance of mild steel (MS) in 0.5 M H₂SO₄ and HCl solution with specific concentrations of the intermixture of rosemary and cinanamon cassia essential oil extracts (RCC) was studied by potentiodynamic polarization method, open circuit potential analysis (OCP) and optical macroscopy. Information obtained showed RCC effectively inhibited MS corrosion from the lowest to the highest concentrations in both acids with lowest inhibition result of 95.30% and 94.19%, and highest inhibition efficiency of 99.21% and 97.69%. RCC exhibited dominant cathodic inhibition effect in H₂SO₄ due to suppression of the reduction reactions while in HCl RCC displayed mixed inhibition properties due to surface coverage effect in the presence of Cl^? anions. OCP showed RCC increased the thermodynamic tendency of MS to corrosion in H₂SO₄ solution despite effective inhibition performance with significant electronegative shift in corrosion potential. In HCl significant electropositive potential displacement was observed relative to the potential of the control MS due to adsorbed protonated RCC molecules unto the steel. Adsorption of RCC molecules on MS aligned with Langmuir, Frumkin and Freundlich isotherm models through chemisorption mechanism in both acids with average correlation coefficient value above 0.9. Optical images of MS in both acids without RCC showed severe surface degradation with the degree of degradation being higher from H₂SO₄ solution. Optical images from RCC inhibited steel depict effective surface protection.