镍钛记忆合金胆道内支架治疗恶性高位胆管梗阻

应用镍钛形状记忆合金胆道内支架管治疗15例胆道恶性狭窄或梗阻，其中肝门部胆管癌11例，胆囊癌3例，肝门部肝癌1例。所有病人术前均有严重梗阻性黄疸（血清总胆红素平均值286．5μmo/L），经剖腹术或PTCD途径放置内支架管后14例黄疸在1～6周内消退，1例在住院期间死于多器官功能衰竭。对恶性高位胆道梗阻或狭窄所引起的黄疸行姑息性减黄治疗时，置入镍钛形状记忆合金支架作内引流是较为理想的治疗方法。

新型功能材料在机械工程中的应用

新型功能材料具有优异性能和特殊功能,把人类支配自然的能力提高到一个新的水平。文中主要介绍形状记忆材料、超磁致伸缩材料、梯度功能材料、智能材料等在机械工程领域中的应用。

Microstructures and mechanical properties of nanocrystalline NiTi intermetallics formed by mechanosynthesis

The formulation of nanocrystallinc NiTi shape memory alloys has potential effects in mechanical stimulation and medical im- plantology. The present work elucidates the effect of milling time on the product＇s structural characteristics, chemical composition, and mi- crohardness for NiTi synthesized by mechanical alloying for different milling durations. Increasing the milling duration led to the formation of a nanocrystalline NiTi intermetallic at a higher level. The formation of nanocrystalline materials was directed through cold fusion, fractur- ing, and the development of a steady state, which were influenced by the accumulation of strain energy. In the morphological study, uninter- rupted cold diffusion and fracturing were visualized using transmission electron microscopy. Particle size analysis revealed that the mean particle size was reduced to -93 μm after 20 h of milling. The mechanical strength was enhanced by the formation of a nanocrystalline in- termetallic phase at longer milling time, which was confirmed by the results of Vickers hardness analyses.

Improving exposure of anodically ordered Ni-Ti-O and corrosion resistance and biological properties of NiTi alloys by substrate electropolishing

Although Ni-Ti-O nanopores(NPs) can be fabricated by anodization of mechanically polished NiTi alloys, the top disordered layer is difficult to remove thus hindering the functionality of the Ni-Ti-O NPs. In this work, an electropolishing(EP) pretreatment was performed on the NiTi substrate prior to anodization to thoroughly expose the NPs. Our results show that the EP pretreatment for 5 min perfectly removes the top disordered layer on the Ni-Ti-O NPs to expose the underlying NPs and consequently, the corrosion resistance and antibacterial ability are enhanced. The exposed NPs can elongate bone marrow mesenchymal stem cells, which may be responsible for the upregulated alkaline phosphatase activity, secretion of Type I collagen, and extracellular matrix mineralization. These results suggest that EP is a desirable pretreatment before anodization of the NiTi alloys because the irregular surface layer on the Ni-Ti-O NPs can be removed to enhance the corrosion resistance and biological functions.

Self-assembled nanosheets on NiTi alloy facilitate endothelial cell function and manipulate macrophage immune response

Stenting has been widely adopted for the treatment of cardiovascular diseases,but the complications such as in-stent restenosis and late stent thrombosis cannot be completely avoided,which are closely related to endothelial dysfunction and inflammatory response.In the present work,oxide nanosheets were grown on the surface of nearly equiatomic Ni Ti alloy by alkaline corrosion(AC),aiming at yielding favorable endothelial functionality and immune microenvironment.The results show nanosheets mainly composed of TiO_(2),Ni(OH)_(2),and K_(2)TiO_(3)can be grown on the alloy in KOH solution of 2.5–15 M at room temperature.The AC-treated samples significantly promote endothelial cell(EC)functionality such as proliferation,migration,NO production,VEGF secretion,and angiogenesis.In addition,the sample grown in KOH of 15 M can switch macrophages to an anti-inflammatory M2 phenotype and up-regulate the gene expression of VEGF to facilitate EC functionality.These results demonstrate that the nanosheets can directly and indirectly up-regulate EC functionality,possibly leading to rapid re-endothelialization of the stents thus addressing the stent-related complications.

Porous nickel–titanium alloy prepared by gel-casting

To explore the preparation of porous nickel- titanium alloy with excellent properties, larger size and complex shape, the premixed powder of Ni and Ti with atomic ratio of 1：1 was shaped by gel-casting. The effects of solids loading and the content of dispersant on flow ability of nickel-titanium slurry and the mechanical properties of nickel-titanium sintered body were studied. The drying models under different solids loading were also discussed. The results show that the viscosity of slurries significantly increases with an increase in solids loading. After a proper process of drying, the green body with complex shape is obtained. The sintered body with porosity rate reaching up to 49.5 % and compression strength reaching to 364.74 MPa could meet the basic demands of implant materials.

Corrosion behavior,antibacterial ability,and osteogenic activity of Zn-incorporated Ni-Ti-O nanopore layers on NiTi alloy

Development of bone fixation devices with excellent corrosion resistance,antibacterial ability,and osteogenic activity is critical for promoting fracture healing.In this study,Zn-incorporated nanopore(NP)layers were prepared on the NiTi alloy through anodization and hydrothermal treatment.Results show that Zn can be evenly incorporated into the NP layers in the form of ZnTiO_(2).The Zn-incorporated samples exhibit good corrosion resistance and significantly reduce Ni^(2+)release.Meanwhile,the samples can continuously release Zn^(2+),which is responsible for excellent long-term antibacterial ability.Furthermore,the synergetic effect of Zn^(2+) release and nanoporous structure of the NP layers endues the NiTi alloy excellent osteogenic activity,as verified by upregulated alkaline phosphatase activity,secretion of type I collagen,and extracellular matrix mineralization.Therefore,Zn-incorporated Ni-Ti-O NP layers have great potential as biomedical coatings of NiTi-based implant materials.