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Influence of screw length and diameter on tibial strain energy density distribution after anterior cruciate ligament reconstruction 总被引:1,自引:0,他引:1
Jie Yao Guan-Ming Kuang Duo Wai-Chi Wong Wen-Xin Niu Ming Zhang Yu-Bo Fan 《Acta Mechanica Sinica》2014,30(2):241-249
Postoperative tunnel enlargement has been frequently reported after anterior cruciate ligament(ACL)reconstruction.Interference screw,as a surgical implant in ACL reconstruction,may influence natural loading transmission and contribute to tunnel enlargement.The aims of this study are(1)to quantify the alteration of strain energy density(SED)distribution after the anatomic single-bundle ACL reconstruction;and(2)to characterize the influence of screw length and diameter on the degree of the SED alteration.A validated finite element model of human knee joint was used.The screw length ranging from 20 to 30 mm with screw diameter ranging from 7 to 9 mm were investigated.In the post-operative knee,the SED increased steeply at the extra-articular tunnel aperture under compressive and complex loadings,whereas the SED decreased beneath the screw shaft and nearby the intra-articular tunnel aperture.Increasing the screw length could lower the SED deprivation in the proximal part of the bone tunnel;whereas increasing either screw length or diameter could aggravate the SED deprivation in the distal part of the bone tunnel.Decreasing the elastic modulus of the screw could lower the bone SED deprivation around the screw.In consideration of both graft stability and SED alteration,a biodegradable interference screw with a long length is recommended,which could provide a beneficial mechanical environment at the distal part of the tunnel,and meanwhile decrease the bone-graft motion and synovial fluid propagation at the proximal part of the tunnel.These findings together with the clinical and histological factors could help to improve surgical outcome,and serve as a preliminary knowledge for the following study of biodegradable interference screw. 相似文献
233.
Wang X Han X Xie S Kuang Q Jiang Y Zhang S Mu X Chen G Xie Z Zheng L 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(8):2283-2289
A morphology evolution of SnO(2) nanoparticles from low-energy facets (i.e., {101} and {110}) to high-energy facets (i.e., {111}) was achieved in a basic environment. In the proposed synthetic method, octahedral SnO(2) nanoparticles enclosed by high-energy {111} facets were successfully synthesized for the first time, and tetramethylammonium hydroxide was found to be crucial for the control of exposed facets. Furthermore, our experiments demonstrated that the SnO(2) nanoparticles with exposed high-energy facets, such as {221} or {111}, exhibited enhanced catalytic activity for the oxidation of CO and enhanced gas-sensing properties due to their high chemical activity, which results from unsaturated coordination of surface atoms, superior to that of low-energy facets. These results effectively demonstrate the significance of research into improving the physical and chemical properties of materials by tailoring exposed facets of nanomaterials. 相似文献
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Xu L Kuang H Xu C Ma W Wang L Kotov NA 《Journal of the American Chemical Society》2012,134(3):1699-1709
Multiple properties of plasmonic assemblies are determined by their geometrical organization. While high degree of complexity was achieved for plasmonic superstructures based on nanoparticles (NPs), little is known about the stable and structurally reproducible plasmonic assemblies made up from geometrically diverse plasmonic building blocks. Among other possibilities, they open the door for the preparation of regiospecific isomers of nanoscale assemblies significant both from a fundamental point of view and optical applications. Here, we present a synthetic method for complex assemblies from NPs and nanorods (NRs) based on selective modification of NRs with DNA oligomers. Three types of assemblies denoted as End, Side, and Satellite isomers that display distinct elements of regiospecificity were prepared with the yield exceeding 85%. Multiple experimental methods independently verify various structural features, uniformity, and stability of the prepared assemblies. The presence of interparticle gaps with finely controlled geometrical parameters and inherently small size comparable with those of cellular organelles fomented their study as intracellular probes. Against initial expectations, SERS intensity for End, Side, and Satellite isomers was found to be dependent primarily on the number of the NPs in the superstructures rationalized with the help of electrical field simulations. Incubation of the label-free NP-NR assemblies with HeLa cells indicated sufficient field enhancement to detect structural lipids of mitochondria and potentially small metabolites. This provided the first proof-of-concept data for the possibility of real-time probing of the local organelle environment in live cells. Further studies should include structural optimization of the assemblies for multitarget monitoring of metabolic activity and further increase in complexity for applications in transformative optics. 相似文献
236.
W Yan L Xu C Xu W Ma H Kuang L Wang NA Kotov 《Journal of the American Chemical Society》2012,134(36):15114-15121
Chirality at the nanometer scale represents one of the most rapidly developing areas of research. Self-assembly of DNA-nanoparticle (NP) hybrids enables geometrically precise assembly of chiral isomers. The concept of a discrete chiral nanostructure of tetrahedral shape and topology fabricated from four different NPs located in the corners of the pyramid is fundamental to the field. While the first observations of optical activity of mixed pyramidal assemblies were made in 2009 ( Chen , W. ; Nano Lett. 2009 , 9 , 2153 - 2159 ), further studies are difficult without finely resolved optical data for precisely organized NP pyramidal enantiomers. Here we describe the preparation of a family of self-assembled chiral pyramids made from multiple metal and/or semiconductor NPs with a yield as high as 80%. Purposefully made R- and S-enantiomers of chiral pyramids with four different NPs from three different materials displayed strong chiroptical activity, with anisotropy g-factors as high as 1.9 × 10(-2) in the visible spectral range. Importantly, all NP constituents contribute to the chiroptical activity of the R/S pyramids. We were able to observe three different circular dichroism signals in the range of 350-550 nm simultaneously. They correspond to the plasmonic oscillations of gold, silver, and bandgap transitions of quantum dots. Tunability of chiroptical bands related to these transitions is essential from fundamental and practical points of view. The predictability of optical properties of pyramids, the simplicity of their self-assembly in comparison with lithography, and the possibility for polymerase chain reaction-based automation of their synthesis are expected to facilitate their future applications. 相似文献
237.
Fu‐Der Mai Ting‐Chu Hsu Yu‐Chuan Liu Kuang‐Hsuan Yang 《Journal of Raman spectroscopy : JRS》2012,43(6):724-729
In this work, we propose a new electrochemical method to prepare surface‐enhanced Raman scattering (SERS)‐active silver substrates in nitric acid solutions. Experimental results indicate that the SERS intensity of adsorbed Rhodamine 6G (R6G) can be significantly increased, as compared with that of R6G adsorbed on a SERS‐active Ag substrate prepared by an electrochemical method in a chloride‐containing solution, which was generally employed in the literature. Moreover, the SERS of R6G on the newly developed substrate (prepared in a nitric acid solution) still performs well at a high temperature of 250 °C. However, the enhancement capability of the SERS‐active substrate prepared in a chloride‐containing solution is seriously destroyed at temperatures higher than 150 °C. Further investigations indicate that the oxidation states of roughened Ag substrates prepared in nitric acid solutions under different experiment conditions have less influence on the corresponding SERS performances. Instead, different surface morphologies of roughened Ag substrates and different contents of nitrogen‐containing dopping ions on the roughened Ag substrates demonstrate significant effects on the corresponding SERS performances. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
238.
Peng Shao Xiao-Yu Kuang Li-Ping Ding Ming-Min Zhong Zhen-hua Wang 《Physica B: Condensed Matter》2012,407(21):4379-4386
Equilibrium geometric structures, stabilities, and electronic properties of SinCu2 (n=1–8) clusters and pure silicon Sin (n=3–10) clusters are investigated systematically by exchange-correlation density functional (B3LYP). The optimized geometries show that the most stable isomers have 3D structure for n=2, 4–8, and Cu-substituted Sin+2 clusters is dominating growth pattern for the SinCu2 clusters. The calculated averaged binding energies, fragmentation energies, second-order difference of energies, and the HOMO–LUMO gaps show that Si2Cu2 and Si5Cu2 clusters have enhanced relative stabilities and chemical stability than their neighboring clusters. Electronic properties of SinCu2 (n=1–8) clusters are studied by calculating the natural population analysis and electrostatic potential, where the results show that the two copper atoms always possess positive charge and positive potential surround them. In addition, the VIP, VEA and the chemical hardness (η) are also analyzed and compared. 相似文献
239.
本文通过基于密度泛函理论的第一性原理,研究了纤锌矿结构Al1-xInxN在不同In浓度下的稳固结构,以及电子和光学性质的变化规律。研究表明,AlInN不同In浓度的晶格结构都很稳定,说明AlInN的兼容性很好。晶格常数随In浓度的增大不断增大,而混晶的带隙则不断减小。并且随In浓度的增大,混晶在紫外光区的吸收系数、反射系数及折射率增大,吸收边、吸收峰和反射峰蓝移,且这两个峰的峰值减小。AlInN的吸收、反射和折射率曲线在Eg处出现峰值行为,此Eg处的峰值大小随In浓度的增加而增大。当In浓度达到87.5%时,混晶AlInN在紫外光区的吸收、反射和折射能力均达到最强,表明此时的掺杂效果最好。 相似文献
240.