液压支架快速撤除技术研究应用

新汶矿业集团经过探索和实践,研究运用了差异互补式全掩护支护技术、掩护支架自牵引联动装置工艺、矿车运输、滑移运输多用轨道、自动找正装车平台、液控调整装置等新技术、新工艺,做到了液压支架综合流程快速回撤,实现了高效化、连贯化安全回撤,取得了良好的经济效益。     

Development of biodegradable scaffold using polylactic acid and polycaprolactone for cardiovascular application

The limitations of newly synthesized biodegradable stents are low mechanical strength, fracture stiffness, and fast degradability of the polymers. A cylindrical polymeric scaffold was proposed in combination of polylactic acid and polycaprolactone. The tensile strength of the blend was increased twice, though elongation has reduced threefold. The blend illustrated no chemical interaction between polymers. The scaffold was coated with docetaxel, and sustained release profile was observed for 56 days. The degradation of the scaffold was evaluated through change in mechanical properties, weight variation, and morphological studies. The developed hemocompatible polymeric scaffold may be used as for the cardiovascular application.     

镁合金支架材料AZ81表面PLGA(PTX)/PLLA/MAO涂层的研究

在AZ81镁合金表面制备了抗腐蚀和药物释放复合涂层,并对其耐蚀性、药物释放性能及生物相容性进行研究。DSC和红外光谱数据表明,紫杉醇均匀分散在PLGA体系中。药物释放数据表明30 d后,药物释放率在80%左右。SEM、电化学阻抗、极化及镁离子释放数据表明,PLLA涂层通过有效填充微弧氧化膜表面的微孔与裂缝提高了镁合金的耐腐蚀性。血液和细胞实验表明涂层镁合金血液相容性良好,无细胞毒性。     

基于仿真技术的血管支架工艺设置的研究

医用冠脉血管支架加工工艺复杂，工艺条件的设置对支架的性能有较大的影响。为清晰的了解压握、扩张尺寸设置对支架性能的影响，利用计算机仿真技术研究不同工艺设置对支架性能的影响。通过研究发现：压握工况设置下的支架安全性能随压握尺寸减小而变差；扩张工况设置下的支架安全性能随扩张尺寸减小而变好；并且不同的压握、扩张条件对支架的应力也产生一定的影响。结果表明：可以利用仿真技术预见不同的工艺设置对支架的性能影响，完善工艺设置。     

Macro- and microscale variables regulate stent haemodynamics,fibrin deposition and thrombomodulin expression

Drug eluting stents are associated with late stent thrombosis (LST), delayed healing and prolonged exposure of stent struts to blood flow. Using macroscale disturbed and undisturbed fluid flow waveforms, we numerically and experimentally determined the effects of microscale model strut geometries upon the generation of prothrombotic conditions that are mediated by flow perturbations. Rectangular cross-sectional stent strut geometries of varying heights and corresponding streamlined versions were studied in the presence of disturbed and undisturbed bulk fluid flow. Numerical simulations and particle flow visualization experiments demonstrated that the interaction of bulk fluid flow and stent struts regulated the generation, size and dynamics of the peristrut flow recirculation zones. In the absence of endothelial cells, deposition of thrombin-generated fibrin occurred primarily in the recirculation zones. When endothelium was present, peristrut expression of anticoagulant thrombomodulin (TM) was dependent on strut height and geometry. Thinner and streamlined strut geometries reduced peristrut flow recirculation zones decreasing prothrombotic fibrin deposition and increasing endothelial anticoagulant TM expression. The studies define physical and functional consequences of macro- and microscale variables that relate to thrombogenicity associated with the most current stent designs, and particularly to LST.     

Nickel-free stainless steel avoids neointima formation following coronary stent implantation

Abstract

SUS316L stainless steel and cobalt–chromium and platinum–chromium alloys are widely used platforms for coronary stents. These alloys also contain nickel (Ni), which reportedly induces allergic reactions in some subjects and is known to have various cellular effects. The effects of Ni on neointima formation after stent implantation remain unknown, however. We developed coronary stents made of Ni-free high-nitrogen austenitic stainless steel prepared using a N₂-gas pressurized electroslag remelting (P-ESR) process. Neointima formation and inflammatory responses following stent implantation in porcine coronary arteries were then compared between the Ni-free and SUS316L stainless steel stents. We found significantly less neointima formation and inflammation in arteries implanted with Ni-free stents, as compared to SUS316L stents. Notably, Ni²⁺ was eluted into the medium from SUS316L but not from Ni-free stainless steel. Mechanistically, Ni²⁺ increased levels of hypoxia inducible factor protein-1α (HIF-1α) and its target genes in cultured smooth muscle cells. HIF-1α and their target gene levels were also increased in the vascular wall at SUS316L stent sites but not at Ni-free stent sites. The Ni-free stainless steel coronary stent reduces neointima formation, in part by avoiding activation of inflammatory processes via the Ni-HIF pathway. The Ni-free-stainless steel stent is a promising new coronary stent platform.     

大倾角滑放工作面施工中技术难点的处理

大倾角滑放工作面通过调整倾斜,既符合《煤矿安全规程》之规定,又减少了成本的投入,符合高产高效工作面的要求。同时,通过工作面的缩面开采,减少了煤柱损失,提高了煤炭资源回收率,并创造了可观的经济效益。     

Influence of high-porosity mesh stent on hemodynamics of intracranial aneu- rysm： A computational study

This paper studies the influence of a High-Porosity Mesh （HPM） stent on the hemodynamic characteristics in the intracranial aneurysm based on the Computational Fluid Dynamics （CFD）. An idealized basilar tip aneurysm model and a HPM stent model are built. The pulsating blood flow in a cardiac cycle is computationally simulated for non-stented and stented models, to provide a wealth of information of the spatio-temporally varying blood flow field. The influence of the stent placement on the hemodynamic characteristics is analyzed in terms of distributions of velocity, pressure, Wall Shear Stress （WSS） and Energy Loss （EL）, which are believed to play an important role in the development and rupture of the aneurysm. The numerical results clearly show that the velocity, pressure, WSS and EL of the blood flow in the aneurysm are reduced by 30%-40% when the HPM stent is implanted. These computational results may provide valuable hemodynamic information for clinical neurosurgeon.     

NiTi合金表面微观形貌对血管内皮细胞及血小板黏附的影响

主要探讨血管支架材料--NiTi合金不同表面形貌对牛主动脉血管内皮细胞及血小板黏附的影响.采用机械抛光、机械刻蚀和化学浸蚀的方法制备微孔、微凹槽等微结构特征的NiTi合金表面.利用扫描电镜、粗糙度轮廓仪等对材料表面微观形貌和平均粗糙度进行表征,并测定微孔和微凹槽的材料表面对血小板及血管内皮细胞黏附的影响.结果表明:NiTi合金基体表面制备纳米级粗糙度的微孔和微凹槽等不同微观形貌对血小板黏附的影响不显著,但可明显促进内皮细胞的黏附;具有微孔结构的材料表面黏附的细胞数量最多,且细胞生长状态良好;材料表面微凹槽结构对细胞的早期黏附具有接触诱导效应.微粗糙化的各种不同材料表面形貌对血小板黏附的影响不显著.