Improved biological performance of magnesium by micro-arc oxidation

Magnesium and its alloys have recently been used in the development of lightweight, biodegradable implant materials. However, the corrosion properties of magnesium limit its clinical application. The purpose of this study was to comprehensively evaluate the degradation behavior and biomechanical properties of magnesium materials treated with micro-arc oxidation (MAO), which is a new promising surface treatment for developing corrosion resistance in magnesium, and to provide a theoretical basis for its further optimization and clinical application. The degradation behavior of MAO-treated magnesium was studied systematically by immersion and electrochemical tests, and its biomechanical performance when exposed to simulated body fluids was evaluated by tensile tests. In addition, the cell toxicity of MAO-treated magnesium samples during the corrosion process was evaluated, and its biocompatibility was investigated under in vivo conditions. The results of this study showed that the oxide coating layers could elevate the corrosion potential of magnesium and reduce its degradation rate. In addition, the MAO-coated sample showed no cytotoxicity and more new bone was formed around it during in vivo degradation. MAO treatment could effectively enhance the corrosion resistance of the magnesium specimen and help to keep its original mechanical properties. The MAO-coated magnesium material had good cytocompatibility and biocompatibility. This technique has an advantage for developing novel implant materials and may potentially be used for future clinical applications.     

电子束熔融制造医用Ti6Al4V在人工模拟体液中耐腐蚀行为

目的 研究电子束熔融技术（EBM）3D打印制备的医用Ti6Al4V不同打印截面在Hank''s模拟人工体液中的电化学腐蚀行为。方法 采用开路电位和动电位极化曲线方法研究了Ti6Al4V不同打印截面,分别记为EBM-XOY面（垂直于打印方向的钛合金截面）和EBM-YOZ面（平行于打印方向的钛合金截面）,在Hank''s模拟人工体液中的电化学腐蚀行为,利用SEM、XRD和金相显微镜分析了其表面形貌和物相组成及其腐蚀机理,并与传统医用锻造Ti6Al4V进行了对比研究。结果 与传统医用锻造Ti6Al4V合金相比,EBM-YOZ面钛合金在Hank’s模拟人工体液中的开路电位、腐蚀电位和腐蚀电流与之相当,显示出与之接近的耐腐蚀性能;EBM-XOY面钛合金的耐腐蚀性能较EBM-XOZ面和传统锻造钛合金稍差,主要原因是EBM-XOY面的α+β相界面积大,α相含量较高,且被优先溶解,因此,耐腐蚀性能较差。结论 电子束熔融制造的Ti6Al4V不同截面的耐腐蚀性能不同,EBM-YOZ面的耐腐蚀性能与传统医用锻造钛合金相当,EBM-XOY面的耐腐蚀性能稍差。     

Liver structural transformation after partial hepatectomy and repeated partial hepatectomy in rats: A renewed view on liver regeneration

BACKGROUND The phenomenon of liver regeneration after partial hepatectomy(PH) is still a subject of considerable interest due to the increasing frequency of half liver transplantation on the one hand, and on the other hand, new surgical approaches which allow removal of massive space-occupying hepatic tumors, which earlier was considered as inoperable. Interestingly, the mechanisms of liver regeneration are extensively studied after PH but less attention is paid to the architectonics of the regenerated organ. Because of this, the question "How does the structure of regenerated liver differ from normal, regular liver?" has not been fully answered yet. Furthermore, almost without any attention is left the liver's structural transformation after repeated hepatectomy(of the re-regenereted liver).To compare the architectonics of the lobules and circulatory bed of normal, regenerated and re-regenerated livers.METHODS The livers of 40 adult, male, albino Wistar rats were studied. 14 rats were subjected to PH-the 1st study group(SG_1); 10 rats underwent repeated PH – the 2nd study group(SG2); 16 rats were subjected to sham operation-control group(CG); The livers were studied after 9 months from PH, and after 6 months from repeated PH. Cytological(Schiff reaction for the determination of DNA concentration), histological(HE, Masson trichrome, CK8 Immunohistochemical marker, transparent slides after Indian Ink injection,), morphometrical(hepatocytes areas, perimeters and ploidy) and Electron Microscopical(Scanning Electron Microscopy of corrosion casts) methods were used.RESULTS In the SG_1 and SG_2, the area of hepatocytes and their perimeter are increased compared to the CG(P 0.05). However, the areas and perimeters of the hepatocytes of the SG_1 and SG_2 groups reveal a lesser difference. In regenerated(SG_1) and re-regenerated(SG_2) livers, the hepatocytes form the remodeled lobules, which size(300-1200 μm) exceeds the sizes of the lobules from CG(300-600 μm). The remodeled lobules(especially the "mega-lobules" with the sizes 1000-1200 μm) contain the transformed meshworks of the sinusoids, the part of which is dilated asymmetrically. This meshwork might have originated from the several portal venules(interlobular and/or inlet). The boundaries between the adjacent lobules(including mega-lobules) are widened and filled by connective tissue fibers, which gives the liver parenchyma a nodular look. In SG_2 the unevenness of sinusoid diameters, as well as the boundaries between the lobules(including the mega-lobules) are more vividly expressed in comparison with SG_1. The liver tissue of both SG_1 and SG_2 is featured by the slightly expressed ductular reaction.CONCLUSION Regenerated and re-regenerated livers in comparison with normal liver contain hypertrophied hepatocytes with increased ploidy which together with transformed sinusoidal and biliary meshworks form the remodeled lobulli.     

两种不同含氯消毒剂对手术器械的锈蚀反应及消毒效果观察

目的 观察两种不同含氯消毒剂对手术器械的锈蚀反应及消毒效果.使基层医院在手工清洗传染病污染器械过程中,既可防止器械产生锈蚀,又可避免清洗人员职业感染风险.方法 分别采用含氯泡腾片、含氯消毒粉稀释液浸泡手术器械.观察两组消毒剂不同时间对器械产生锈蚀情况;分别采用含氯泡腾片、含氯消毒粉稀释液浸泡血液污染器械4 h,观察器械表层情况及其两组消毒液存放48 h细菌监测情况.结果 含氯泡腾片稀释液浸泡器械仅5-10 min开始起锈蚀反应,而含氯消毒粉稀释液浸泡器械48 h则无锈蚀反应;泡腾片稀释液与消毒粉稀释液相比较其器械锈蚀率差异有统计学意义;两组消毒液分别浸泡血液污染器械4 h,其器械表层情况有差异;其两组消毒液存放48 h细菌监测合格率均达100%.结论 基层医院无清洗消毒设备时.用手工清洗传染病污染的器械前,使用含氯消毒粉稀释液浸泡器械,既不使器械产生锈蚀.又可达到消毒效果.     

蛋白质黏附对镍铬合金在人工唾液中腐蚀行为的影响

目的 研究两种不同蛋白质黏附对镍铬合金在人工唾液中腐蚀行为的影响。方法 实验组中选择小牛血清蛋白（BSA）和溶菌酶（LSZ）作为目标蛋白,分别与人工唾液混合制成不同浓度的试剂,对照组选择纯人工唾液（AS）,将镍铬合金试件分别浸泡在实验组与对照组溶液中24 h,通过测量动电位极化曲线进行拟合,得到电化学腐蚀参数值,包括腐蚀电流值（I_corr）、极化阻抗值（R_p）、破钝电位值（E_br）,以此观察蛋白质黏附对材料腐蚀行为的影响及其与浓度的相关性。结果 BSA组与对照组中测得腐蚀电流值（I_corr）从小到大依次为1% BSA、0.1% BSA、AS、0.01% BSA（P<0.05）,极化阻抗值（R_p）从小到大依次为AS、0.01% BSA、0.1% BSA、1% BSA（P<0.05）,破钝电位值（E_br）从小到大依次为AS、0.01% BSA、0.1% BSA、1% BSA（P<0.05）; LSZ组与对照组中测得腐蚀电流值（I_corr）从小到大依次为AS、0.22% LSZ、0.022% LSZ（P<0.05）,极化阻抗值（R_p）从小到大依次为AS、0.022% LSZ、0.22% LSZ（P<0.05）,破钝电位值（E_br）从小到大依次为AS、0.022% LSZ、0.22% LSZ（P<0.05）。结论 镍铬合金经蛋白溶液作用后,极化阻抗值及破钝电位均显著升高,且蛋白浓度越高,极化抗阻值和破钝电位值升高越显著。     

Corrosion of stainless steel sternal wire after long-term implantation

A variety of metallic components have been used in medical devices where lifelong durability and physical strength are demanded. To investigate the in vivo changes of implanted metallic medical devices in humans, stainless steel sternal wires removed from patients were evaluated. Stainless steel (316L) sternal wires removed from four patients after 10, 13, 22, and 30 years of implantation were evaluated using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Macroscopically, the removed specimens maintained their metallic luster and color. Under SEM, small holes were observed sporadically at 10 years and they tended to connect in the drawing direction. The longer the implanted duration, the more numerous and deeper were the crevices observed. By EDS, sulfur, phosphorus, and calcium were identified in all areas at 10 years, in addition to the component elements of stainless steel, comprising iron, chromium, nickel, and manganese. Corrosion products observed at 30 years were identified as calcium phosphate. In conclusion, stainless steel sternal wires develop corroded pores that grow larger and deeper with time after implantation; however, the pores remain shallow even after decades of implantation and they may not be a cause of mechanical failure. An amount of metal ions equivalent to the corroded volume must have been released into the human body, but the effect of these metal ions on the body is not apparent.     

应用钨丝弹簧圈栓塞后在体内溶解现象的临床观察

目的 通过检测钨丝弹簧圈血管内治疗前后30例病人血钨浓度以证实其在体内的溶解和吸收现象以及吸收与再通的关系。方法 随机抽取应用钨丝弹簧圈栓塞的30例病人进行调查。动静脉畸形（AVM）14例，硬脑膜动静脉瘘（DAVF）6例，动静脉瘘（AVF）5例，颈动脉海绵窦瘘（CCF）2例，动脉瘤3例。分别于术前及术后留取非抗凝血5ml并进行高速离心，取血清应用电感耦连等质子光谱仪（ICP-MS）经双盲法测定血钨浓度并进行自身配对统计学处理。对栓塞后的病人全部检查其肝肾功能及电解质。结果 栓塞后血钨浓度明显升高（P〈0．01）。虽然血钨浓度明显升高，但病人的肝肾功能及电解质无异常。结论 钨丝弹簧圈栓塞后在体内存在溶解和吸收现象，但金属钨对人体并不产生毒性。弹簧圈吸收后，动脉瘤不会复发，但AVM肯定复发。     

Surface Analysis of Indigenous Stainless Steel Miniplates Used in Facial Fractures

Aims and Objective  

The stainless steel (SS) implants are economical and easily available. Tissue reaction due corrosion of metallic plates and release of metal particles in surrounding soft tissues is the main reason put forward by advocates of removal of SS miniplates after period of fracture healing. The objectives of this study were to examine the surfaces changes and corrosion in relation to indigenously manufactured SS mini-plates, both due to intraoperative instrumentation and tissue reaction. The composition of these mini-plates and any metal release in surrounding soft tissues was also studied.     

New approach of electrochemical systems dynamics in the time domain under small-signal conditions: II. Modelling the responses of electrochemical systems by numerical inversion of Laplace transforms

In the first part of this work, we showed that numerical inversion of Laplace transform (NILT) methods could be readily applied to compute the responses of electrochemical systems to small input signals from any reasonable model of the system immittance that is the impedance for current-controlled techniques and the admittance for potential-controlled techniques. The aim of this second article is to provide some applications examples in different fields of electrochemical kinetics. The response of a polymer exchange membrane fuel cell to a small current pulse is computed. The responses of corrosion systems to small potential step/ramp signals are also dealt with. The response of electrochemical systems to a sinusoidal perturbation of electrode potential is investigated. Finally, both Faradaic and non-Faradaic components of the total current are computed by NILT methods under potential- and current-controlled conditions.