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排序方式: 共有251条查询结果,搜索用时 15 毫秒
1.
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。 相似文献
2.
生物材料用于人体必须要具备生物相容性。尤其是与血液相接触的材料如血管内支架必须要具备血液相容性。材料的表面特性直接影响血液系统中是否会出现血栓。本文针对金属血管内支架的表面特性、与血液的界面反应以及用于提高血液相容性的低温等离子表面改性进行了简要综述 相似文献
3.
C. S. Lim P. Eng S. C. Lin C. K. Chua Y. T. Lee 《The International Journal of Advanced Manufacturing Technology》2002,20(1):44-49
Rapid prototyping (RP) and rapid tooling (RT) techniques can be applied to the field of medicine primarily because of their
ability to produce customised profiles and geometries in relatively short lead times. In this paper, the process by which
these techniques can be applied for the production of customised tracheobronchial stents for the purpose of maintaining patency
in an occluded respiratory tract is described. A comparison of RP systems was carried out to establish the preferred RP method
to produce the master model. The vacuum casting RT process was then used to produce the stent. 相似文献
4.
A neural network model with high nonlinear recognition capability was constructed to describe the relationship between the deformation impact factors and the deformation results of vascular stent.Then,using the weighted correction method with the attached momentum term,the network training algorithm was optimized by introducing learning factor η and momentum factor ψ,so the speed of the network training and the system robustness were enhanced.The network was trained by some practi-cal cases,and the statisti... 相似文献
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AbstractSUS316L 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. 相似文献
7.
Juan M. Jiménez Varesh Prasad Michael D. Yu Christopher P. Kampmeyer Abdul-Hadi Kaakour Pei-Jiang Wang Sean F. Maloney Nathan Wright Ian Johnston Yi-Zhou Jiang Peter F. Davies 《Journal of the Royal Society Interface》2014,11(94)
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. 相似文献
8.
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. 相似文献
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M. Malvè A. Pérez del PalomarA. Mena O. Trabelsi J.L. López-VillalobosA. Ginel F. PanaderoM. Doblaré 《International Communications in Heat and Mass Transfer》2011,38(7):855-862
Endotracheal stenting is a common treatment for tracheal disorders as stenosis, cronic cough or dispnoea episodes. However, medical treatment and surgery are still challenging due to the difficulties in overcoming potential prosthesis complications. In this work we analyze the response of the tracheal wall during breathing and coughing conditions under different stent implantations. A finite element model of a human trachea was developed and used to analyze tracheal deformability after prosthesis implantation under normal breathing and coughing using a fluid-structure interaction approach (FSI). The geometry of the trachea is obtained from computed tomography (CT) images of a healthy patient. A structured hexahedral-based grid for the tracheal wall and an unstructured tetrahedral-based mesh with coincident nodes for the fluid were used to perform the simulations with a finite element-based commercial software code. Tracheal wall is modeled as a fiber reinforced hyperelastic solid material in which the anisotropy due to the orientation of the fibers is taken into account. Deformations of the tracheal cartilage rings and of the muscle membrane, as well as the maximum principal stresses in the wall, are analyzed and compared with those of the healthy trachea in absence of prosthesis. The results showed that, the presence of the stent prevents tracheal muscle deflections especially during coughing. In addition, we proposed a methodology to evaluate, through numerical simulations, the predisposition of the stent to migrate. 相似文献