Design strategy of poly (L-lactic acid) mixed braided stent: The influence of braiding ratio of thick and thin monofilaments

For the design of polymer stents, supportability and flexibility are two important indexes, but they are often difficult to balance. The mixed braiding of monofilaments with different diameters provides a potential solution to balance these two indices. In this study, the influence of mixed braiding on the mechanical properties of the stent was further explored by adjusting the knitting ratio of thick and thin monofilaments. By replacing the monofilaments in the stent with monofilaments with smaller diameters in turn, the changing trend of supportability and flexibility is obtained. The results show that, when the number of thick monofilaments is greater than or equal to that of thin monofilaments, the supportability of the stent can not only be maintained but also the flexibility can be greatly improved. Therefore, mixed braiding has the function of adjusting supportability and flexibility.     

Contact allergies to metal components of the 316 L steel in patients with coronary heart disease

In‐stent restenosis is a complication which impairs the success of coronary stenting. Recently it was supposed that a delayed hypersensitivity reaction to nickel and molybdenum might be one of the triggering factors in in‐stent restenosis. We have performed a retrospective analysis of the data collected in our centre with respect to this hypothesis. Altogether 20 patients were investigated (13 male, 7 female). Patch tests were performed with the standard series of the German Contact Dermatitis Research Group and a metal series containing the metal components of the 316 L stainless steel. A positive patch test reaction to nickel was observed in 2 (10.0%) patients, one of these patients had an in‐stent restenosis, the other had not. None of the patients showed a sensitization to the other metals. Restenoses were predominantly observed in patients with a negative patch test reaction to nickel (6/18 patients). Although it cannot be excluded that metal allergy may play a role in the restenosis process in coronary stenting there is at the moment little evidence for it.     

Smooth contact strategies with emphasis on the modeling of balloon angioplasty with stenting

Critical to the simulation of balloon angioplasty is the modeling of the contact between the artery wall and the medical devices. In standard approaches, the 3D contact surfaces are described by means of C⁰‐continuous facet‐based techniques, which may lead to numerical problems. This work introduces a novel contact algorithm where the target surfaces are described by polynomial expressions with C²‐continuity. On the basis of uniform cubic B‐splines, two different parametrization techniques are presented and compared, while the related implementation of the algorithm into a finite element analysis program is described. Two numerical examples are selected to demonstrate the special merits of the proposed contact formulation. The first example is a benchmark contact problem selected to point out the special features of the proposed strategies. The second example is concerned with the simulation of balloon angioplasty and stenting, where the contact between the balloon, the stent and the artery wall is numerically modeled. A patient‐specific 3D model of a stenotic femoral artery serves as a basis. The study concludes by identifying the changes in the mechanical environment of the artery in terms of contact forces and strains by considering two different stent designs. Copyright © 2008 John Wiley & Sons, Ltd.     

316L不锈钢冠脉支架制造工艺的研究

研究了激光精细雕刻冠状动脉血管支架的制造工艺,对冠脉支架结构设计原则、激光精细雕刻加工参数、热处理工艺进行了探讨.并给出一种冠脉支架结构,进行切割实验,分析了影响切口质量因素及真空热处理工艺、电化学工艺对冠脉支架样品质量的影响.     

冠状动脉支架材料的研究进展

冠状动脉支架置入术作为治疗心血管狭窄引起的冠心病的主要方法之一,得到了较为广泛、深入的研究.从材料的角度系统介绍了冠状动脉支架,包括支架基体材料、支架表面涂层材料和所载药物,并简要说明了药物涂层的组装工艺和冠状动脉支架的发展趋势.     

基于蛋白质组学分析奈比洛尔改善UUO大鼠肾间质纤维化

目的：观察奈比洛尔改善单侧输尿管梗阻（UUO）大鼠肾间质纤维化（RIF）的作用,并利用蛋白质组学探讨其机制。方法：SD大鼠分为：Sham组;UUO组;Neb组（UUO大鼠给予奈比洛尔10 mg·kg-1·d-1,i.g.）。各组分别在造模7 d,14 d和21 d时,麻醉大鼠,分离左侧梗阻肾。HE染色观察肾脏结构,Masson染色测RIF程度。利用蛋白质组学筛选造模21 d,UUO/Sham和Neb/UUO之间共有,且奈比洛尔回调差异蛋白,进行生物信息学分析。Western blot验证关键蛋白表达。结果：与Sham组比较,UUO大鼠RIF呈渐进性加重。奈比洛尔给药21 d显著改善UUO大鼠左肾RIF。与UUO/Sham比较,奈比洛尔回调差异蛋白179个。KEGG富集分析和PPI网络显示,回调差异蛋白主要涉及剪接体通路。Western blot证实Rbm8a、Srsf9、Sart1蛋白表达与蛋白组学结果一致。 结论：奈比洛尔改善UUO大鼠肾间质纤维化可能与调节剪接体密切相关。     

Intimal hyperplasia following implantation of helical-centreline and straight-centreline stents in common carotid arteries in healthy pigs: influence of intraluminal flow?

Intimal hyperplasia (IH) is a leading cause of obstruction of vascular interventions, including arterial stents, bypass grafts and arteriovenous grafts and fistulae. Proposals to account for arterial stent-associated IH include wall damage, low wall shear stress (WSS), disturbed flow and, although not widely recognized, wall hypoxia. The common non-planarity of arterial geometry and flow, led us to develop a bare-metal, nitinol, self-expanding stent with three-dimensional helical-centreline geometry. This was deployed in one common carotid artery of healthy pigs, with a straight-centreline, but otherwise identical (conventional) stent deployed contralaterally. Both stent types deformed the arteries, but the helical-centreline device additionally deformed them helically and caused swirling of intraluminal flow. At sacrifice, one month post stent deployment, histology revealed significantly less IH in the helical-centreline than straight-centreline stented vessels. Medial cross-sectional area was not significantly different in helical-centreline than straight-centreline stented vessels. By contrast, luminal cross-sectional area was significantly larger in helical-centreline than straight-centreline stented vessels. Mechanisms considered to account for those results include enhanced intraluminal WSS and enhanced intraluminal blood–vessel wall mass transport, including of oxygen, in the helical-centreline stented vessels. Consistent with the latter proposal, adventitial microvessel density was lower in the helical-centreline stented than straight-centreline stented vessels.     

武汉火车站三跨刚构拱桥模板工程关键技术

武广客运专线新建武汉火车站工程的三跨连续刚构拱桥10联平行布置,桥梁外形为复杂空间不可展曲面,桥梁体量大,设计要求达到饰面清水混凝土外观效果,同时工期紧张.针对工程的具体情况,工程中采用了型钢支撑架和多支点横向移动模架两种形式,论述了模板及支撑体系从设计到使用阶段相应的关键技术.结果表明,应用该关键技术,三跨连续刚构拱桥顺利得以完成,达到了质量和工期要求.     

液压支架电液控制系统

一种全新的煤矿井下液压支架电液控制系统,使液压支架与采煤机、刮板输送机联动、自动控制,实现综合机械化采煤工作面的高产、高效、安全、全自动化生产。目前在神化集团神东煤炭公司等矿井已经广泛使用这一新技术。     

高地应力软岩隧道合理支护方案研究

 基于高地应力软岩隧道明显流变效应的特点,提出在喷锚网支护的基础上增设U型钢可压缩支架和泡沫混凝土填充层的支护方案。利用建立的U型钢连接件力学模型和围岩与支架接触模型,分析2种支护方案下,宜昌-巴东(宜巴)高速公路峡口高地应力软岩隧道的长期稳定性。研究表明：(1) 建立的U型钢可压缩支架的连接件力学模型和围岩与支架之间的接触模型可以很好地反映支架缩动性与摩阻力之间的关系;(2) U型钢可压缩支架和泡沫混凝土填充层的联合支护既可以吸收围岩的流变变形,减小二次衬砌上的形变压力,又可以提供稳定的支护力,有利于高地应力软岩隧道的长期稳定。