Biological Safety Evaluation and Surface Modification of Biocompatible Ti–15Zr–4Nb Alloy

We performed biological safety evaluation tests of three Ti–Zr alloys under accelerated extraction condition. We also conducted histopathological analysis of long-term implantation of pure V, Al, Ni, Zr, Nb, and Ta metals as well as Ni–Ti and high-V-containing Ti–15V–3Al–3Sn alloys in rats. The effect of the dental implant (screw) shape on morphometrical parameters was investigated using rabbits. Moreover, we examined the maximum pullout properties of grit-blasted Ti–Zr alloys after their implantation in rabbits. The biological safety evaluation tests of three Ti–Zr alloys (Ti–15Zr–4Nb, Ti–15Zr–4Nb–1Ta, and Ti–15Zr–4Nb–4Ta) showed no adverse (negative) effects of either normal or accelerated extraction. No bone was formed around the pure V and Ni implants. The Al, Zr, Nb, and Ni–Ti implants were surrounded by new bone. The new bone formed around Ti–Ni and high-V-containing Ti alloys tended to be thinner than that formed around Ti–Zr and Ti–6Al–4V alloys. The rate of bone formation on the threaded portion in the Ti–15Zr–4Nb–4Ta dental implant was the same as that on a smooth surface. The maximum pullout loads of the grit- and shot-blasted Ti–Zr alloys increased linearly with implantation period in rabbits. The pullout load of grit-blasted Ti–Zr alloy rods was higher than that of shot-blasted ones. The surface roughness (Ra) and area ratio of residual Al₂O₃ particles of the Ti–15Zr–4Nb alloy surface grit-blasted with Al₂O₃ particles were the same as those of the grit-blasted Alloclassic stem surface. It was clarified that the grit-blasted Ti–15Zr–4Nb alloy could be used for artificial hip joint stems.     

Custom-Made Zirconium Dioxide Implants for Craniofacial Bone Reconstruction

Reconstruction of the facial skeleton is challenging for surgeons because of difficulties in proper shape restoration and maintenance of the proper long-term effect. ZrO₂ implant application can be a solution with many advantages (e.g., osseointegration, stability, and radio-opaqueness) and lacks the disadvantages of other biomaterials (e.g., metalosis, radiotransparency, and no osseointegration) or autologous bone (e.g., morbidity, resorption, and low accuracy). We aimed to evaluate the possibility of using ZrO₂ implants as a new application of this material for craniofacial bone defect reconstruction. First, osteoblast (skeleton-related cell) cytotoxicity and genotoxicity were determined in vitro by comparing ZrO₂ implants and alumina particle air-abraded ZrO₂ implants to the following: 1. a titanium alloy (standard material); 2. ultrahigh-molecular-weight polyethylene (a modern material used in orbital surgery); 3. a negative control (minimally cytotoxic or genotoxic agent action); 4. a positive control (maximally cytotoxic or genotoxic agent action). Next, 14 custom in vivo clinical ZrO₂ implants were manufactured for post-traumatologic periorbital region reconstruction. The soft tissue position improvement in photogrammetry was recorded, and clinical follow-up was conducted at least 6 years postoperatively. All the investigated materials revealed no cytotoxicity. Alumina particle air-abraded ZrO2 implants showed genotoxicity compared to those without subjection to air abrasion ZrO₂, which were not genotoxic. The 6-month and 6- to 8-year clinical results were aesthetic and stable. Skeleton reconstructions using osseointegrated, radio-opaque, personalized implants comprising ZrO₂ material are the next option for craniofacial surgery.     

Very-High-Cycle Fatigue Behavior of Inconel 718 Alloy Fabricated by Selective Laser Melting at Elevated Temperature

This study investigates the very-high-cycle fatigue (VHCF) behavior at elevated temperature (650 °C) of the Inconel 718 alloy fabricated by selective laser melting (SLM). The results are compared with those of the wrought alloy. Large columnar grain with a cellular structure in the grain interior and Laves/δ phases precipitated along the grain boundaries were exhibited in the SLM alloy, while fine equiaxed grains were present in the wrought alloy. The elevated temperature had a minor effect on the fatigue resistance in the regime below 10⁸ cycles for the SLM alloy but significantly reduced the fatigue strength in the VHCF regime above 10⁸ cycles. Both the SLM and wrought specimens exhibited similar fatigue resistance in the fatigue life regime of fewer than 10⁷–10⁸ cycles at elevated temperature, and the surface initiation mechanism was dominant in both alloys. In a VHCF regime above 10⁷–10⁸ cycles at elevated temperature, the wrought material exhibited slightly better fatigue resistance than the SLM alloy. All fatigue cracks are initiated from the internal defects or the microstructure discontinuities. The precipitation of Laves and δ phases is examined after fatigue tests at high temperatures, and the effect of microstructure on the formation and the propagation of the microstructural small cracks is also discussed.     

Ultimate Load-Carrying Ability of Rib-Stiffened 2024-T3 and 7075-T6 Aluminium Alloy Panels under Axial Compression

Stringer-stiffened panels made of aluminium alloys are often used as structural elements in the aircraft industry. The load-carrying capacity of this type of structure cannot relieve the reduction in strength in the event of local buckling. In this paper, a method of fabrication of rib-stiffened panels made of EN AW-2024-T3 Alclad and EN AW-7075-T6 Alclad has been proposed using single point incremental forming. Panels made of sheets of different thickness and with different values of forming parameters were tested under the axial compression test. A digital image correlation (DIC)-based system was used to find the distribution of strain in the panels. The results of the axial compression tests revealed that the panels had two distinct buckling modes: (i) The panels buckled halfway up the panel height towards the rib, without any appreciable loss of rib stability, and (ii) the rib first lost stability at half its height with associated breakage, and then the panel was deflected in the opposite direction to the position of the rib. Different buckling modes can be associated with the character of transverse and longitudinal springback of panels resulting from local interaction of the rotating tool on the surface of the formed ribs.     

A Simple Method for a Protective Coating on Stainless Steel against Molten Aluminum Alloy Comprising Polymer-Derived Ceramics,Oxides and Refractory Ceramics

A new coating based on polymer-derived ceramics (PDC), oxides and refractory ceramic with a thickness of around 50 µm has been developed to improve the resistance corrosion of stainless steel substrate against molten aluminum alloy in a thermal energy storage (TES) system designed to run at high temperature (up to 600 °C). These coatings implemented by straightforward methods, like tape casting or paintbrush, were coated on planar and cylindrical stainless-steel substrates, pyrolyzed at 700 °C before being plunged for 600 and 1200 h in molten AlSi₁₂ at 700 °C. The stainless-steel substrate appears healthy without intermetallic compounds, characteristic of molten aluminum alloy corrosion. The protective coating against AlSi₁₂ corrosion shows excellent performance and appears interesting for TES applications.     

应用记忆合金环抱器行多发肋骨骨折内固定术治疗连枷胸合并复合伤（多发伤）29例临床观察

目的：观察应用记忆合金环抱器行多发肋骨骨折内固定术治疗连枷胸的临床效果及其在重症胸外伤救治中的作用。方法研究对象为2010年12月—2014年2月之间的29例连枷胸合并复合伤患者,采用记忆合金环抱器行多发肋骨骨折内固定术治疗,对治疗方案及效果进行总结分析。结果本组病人中28例顺利治愈出院,一例因伤情过重死亡。结论应用记忆合金环抱器内固定治疗连枷胸,能够快速恢复胸廓形状及稳定性,缓解疼痛,有助于骨折愈合,效果显著。     

镁基合金生物可降解支架的国内外研究进展

近年来,镁基合金生物可降解支架在血管领域的应用取得了很大进展。镁基合金作为一种生物降解材料,比铁基合金和锌基合金具有一定的优势。然而,镁基合金的降解速度太快,无法与组织愈合的速度相匹配,而且还表现出不均匀腐蚀的特性。因此,研究者们从支架的表面改性、锻造工艺和成分配比等方面优化支架生物金属特性,并且逐步运用到动物实验及临床研究。本综述主要围绕以下3个方面展开：镁基合金生物可降解支架的国内外发展历程;镁基合金生物可降解支架的特性;镁基合金生物可降解支架的研究热点。     

钴合金和钛合金的细胞毒性研究

对植入材料磨损态的Co-29Cr-5Mo(CCM)和Ti-6Al-4V(Ti64)的细胞毒性进行研究。与固溶态相比,在完全培养液中,通过噻唑蓝(MTT)法研究两种合金在不同浸提浓度、不同浸提时间下的材料浸提液对小鼠成纤维细胞(L929)的毒性及影响机制。扫描电子显微镜(SEM)观察腐蚀前后材料表面的变化,ICP发射光谱仪(ICP-MS)检测CCM和Ti64合金中主要金属离子的释放,电化学工作站(CHI760E)表征两种磨损态合金在完全培养液中的腐蚀情况。MTT实验结果表明:磨损态的两种合金随材料浸提浓度和时间的增大,细胞的相对增殖率(RGR)均减小,其中CCM的RGR由98.36%减小至73.28%,细胞毒性由0级升至2级;Ti64的RGR减小至85.86%,细胞毒性升至1级。ICP-MS结果表明,磨损态合金有害离子的释放量随着浸提时间不断上升,浸提至168 h时,磨损态CCM合金Co和Cr释放量分别高达1 249.7和293.9 μg/L;磨损态Ti64合金Al和V释放量分别为30.7和19.7 μg/L。CCM的Tafel曲线和SEM分析表明,在完全培养液中,CCM表面化学位较高的棱、尖角以及微米级沟壑位置发生了缝隙腐蚀,造成金属离子的释放,并对L929细胞的生长和分裂产生抑制作用。     

3D打印钛合金骨小梁多孔结构的拉伸性能

文题释义：3D打印：3D打印技术开创了增材制造的生产方式,即依照3D设计蓝图可将金属粉末等原材料逐层堆积而制成最终产品,擅长构建形状结构复杂的产品与个体化定制,制作特异性假体或植入物,供植入以达到重建等目的,在骨科领域得到了广泛应用。 钛合金骨小梁：是以钛合金粉末为原材料,采用金属3D打印技术通过金属微粒逐层熔融叠加生成的一种类人体骨小梁三维空间网孔结构,其力学性能和生物学性能和人体的松质骨骨小梁极为相似,作为人工植入假体的表面结构,具有非常出色的骨长入效果。 背景：3D打印钛合金多孔结构以其良好的机械性能和生物相容性已经在骨科植入假体设计与临床应用方面得到了快速发展,与涂层假体相比,钛合金骨小梁结构具有骨长入快和骨长入好的优点。为了保证骨科植入物的安全,目前多采用实验方式确定骨小梁结构的拉伸、剪切疲劳和弯曲疲劳强度。 目的：通过力学实验和有限元数值模拟方法研究骨小梁多孔结构的力学性能。 方法：①3D打印钛合金骨小梁拉伸试件实验：设计并制备3D打印钛合金骨小梁拉伸试件,骨小梁结构的丝径为0.28-0.35 mm、孔径为0.71 mm、孔隙率为73%。检测钛合金骨小梁结构的拉伸强度,分析其失效机制,同时分析不同打印位置对骨小梁拉伸强度的影响。②数值模拟实验：利用有限元方法建立包括骨小梁理论结构的拉伸试件实体模型,模拟骨小梁试件的拉伸破坏过程。 结果与结论：①3D打印钛合金骨小梁拉伸试件的极限载荷分布在39.55-47.11 kN之间,等效极限拉伸应力分布在62.79-74.53 MPa之间,拉伸破坏的结果为网状结构断裂,说明钛合金骨小梁具有较高的拉伸强度;②3D打印钛合金骨小梁拉伸试件实验与数值模拟实验均显示,骨小梁试件受到拉伸破坏时的破坏形式为丝径断裂,不会在骨小梁与钛合金实体的结合面发生断裂;③数值模拟实验中骨小梁试件的拉伸破坏载荷低于3D打印钛合金骨小梁拉伸试件,造成该差异的原因主要为：3D打印骨小梁试件的丝径(280-350 μm之间)大于骨小梁的理论丝径(142 μm),而孔径(孔隙率75%)小于骨小梁的理论孔径(孔隙率96%)。 ORCID: 0000-0001-7000-2093(张兰) 中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程     

The molecular mechanism for effects of TiN coating on NiTi alloy on endothelial cell function

The aim of this study is to systematically investigate the molecular mechanism of different effects of nickel titanium (NiTi) alloy surface and titanium nitride (TiN) coating on endothelial cell function. Release of nickel (Ni) ion from bare and TiN-coated NiTi alloys and proliferation of endothelial cells on the two materials were evaluated, and then influence of the two materials on cellular protein expression profiles was investigated by proteomic technology. Subsequently, proteomic data were analyzed with bioinformatics analyses and further validated using a series of biological experiments. Results showed that although the two materials did not affect cell proliferation, the Ni ions released from bare NiTi alloy generated inhibition on pathways associated with actin cytoskeleton, focal adhesion, energy metabolism, inflammation, and amino acid metabolism. In comparison, TiN coating not only effectively prevented release of Ni ions from NiTi alloy, but also promoted actin cytoskeleton and focal adhesion formation, increased energy metabolism, enhanced regulation of inflammation, and promoted amino acid metabolism. Furthermore, the two processes, “the initial mediation of adsorbed serum protein layer to endothelial cell adhesion and growth on the two materials” from our previous study, and “the following action of the two materials on cellular protein expression profile”, were linked up and comprehensively analyzed. It was found that in stage of cell adhesion (within 4 h), release of Ni ions from bare NiTi alloy was very low, and the activation of adsorbed proteins to cell adhesion and growth related biological pathways (such as regulation of actin cytoskeleton, and focal adhesion pathways) was almost as same as TiN-coated NiTi alloy. This indicated that the released Ni ions did not affect the mediation of adsorbed proteins to endothelial cell adhesion. However, in stage of cell growth and proliferation, the release of Ni ions from bare NiTi alloy increased with time and reached a higher level, which inhibited endothelial cell function at molecular level, whereas TiN coating improved endothelial cell function.