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81.
This paper reviews the past, present and future of surface modification of titanium alloy from the point of view of preparation of hard tissue replacement implants. The development of titanium alloy is also described. 相似文献
82.
Surface modification technologies are quite common in the biomedical field to improve the mechanical,chemical, physical and biological properties of implants such as artificial joint and cardiovascular devices. In this paper, recent progress in the investigation of the bioactivity and biocompatibility enhancement of implants using plasma spraying and plasmabased ion implantation (PIII) is described. Plasma sprayed hydroxyapatite (HA) coatings are commonly used as bioactive coatings but the relatively poor adhesion between the coatings and titanium is one of main disadvantages which have limited their biomedical applications. In our recent studies, novel bioactive coatings, such as wollastonite and dicalcium silicate, were deposited onto titanium to enhance the surfaces bioactivity and biocompatibility. Our results indicate that plasma sprayed wollastonite and dicalcium silicate coatings possess excellent bioactivity as well as relatively high bonding strength. Plasma immersion ion implantation was also employed to improve the anti-corrosion and biological properties of implants. 相似文献
83.
Ali Nazari 《Computational Materials Science》2012,51(1):225-232
In the present work, Charpy impact energy of functionally graded steels produced by electroslag remelting composed of graded ferritic or austenitic layers in both crack divider and crack arrester configurations has been modeled by finite element method. The yield stress of each layer was related to the density of the statistically stored dislocations of that layer and assuming by Holloman relation for the corresponding stress-strain curves, tensile strengths of the constituent layers were determined via numerical method. By using load-displacement curves acquired from instrumented Charpy impact tests on primary specimens, the obtained stress-strain curves from uniaxial tensile tests were modified. The data used for each layer in finite element modeling were predicted modified stress-strain curves obtained from strain gradient plasticity theory. A relatively good agreement between experimental results and those obtained from simulation was observed. 相似文献
84.
Surface N-maleylation and N-naphthaloylation of chitin nanofiber (NF) were achieved by reaction with maleic and naphthalic anhydrides in water, respectively. Maleyl and naphthaloyl groups were sufficiently introduced to an amino group on a surface-deacetylated chitin NF. The characteristic nanofiber morphology was maintained after maleylation and naphthaloylation. These NFs were homogeneously dispersed in several organic solvents. Especially, naphthaloyl chitin NF was dispersed even in aromatic solvents, owing to the high level of solvation interactions with the naphthaloyl group. The NF dispersions in those aromatic solvents exhibited a dispersive-to-precipitate transition response at approximately 29 °C. Moreover, the naphthaloyl chitin NF dispersion cut harmful ultraviolet light. The maleyl chitin NF formed a self-standing gel after cross-linking polymerization. 相似文献
85.
介绍了甲醇生产中焦炉煤气精脱硫系统积碳与结焦的危害以及应对方法。通过设备改造及工艺调整等措施,减少各种杂质进入精脱硫系统,使加氢催化剂保持良好效果,实现设备长周期运行。 相似文献
86.
传统基于技术理性的蓝图式总体规划难以适应经济社会快速发展的要求,《重庆市城乡总体规划(2007—2020年)》(2011年修订)探索实践了《城乡规划法》和《城市总体规划修改工作规则》规定的修改程序。增强总体规划的适应性,需要建立动态完善总体规划的机制、加强多层级多部门的协调合作、空间与政策并重,加强对城市宏观发展趋势的把握。 相似文献
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