In order to investigate the real-time cracking behavior of each component of a composite with strong interfacial bonding among lamellae, Ti-18 Nb(at.%) composite was prepared by spark plasma sintering(SPS), followed b...In order to investigate the real-time cracking behavior of each component of a composite with strong interfacial bonding among lamellae, Ti-18 Nb(at.%) composite was prepared by spark plasma sintering(SPS), followed by hot-rolling, annealing, and quenching. The microstructure and mechanical properties were characterized by scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS), micro-region X-ray diffractometry(MRXRD), nanoindentation, and in-situ scanning electron microscopy tensile testing. The results show that the Ti-18 Nb consists of Ti-enriched, diffusion and Nb-enriched zones, and the sharp Nb gradient across different zones leads to inhomogeneous distribution of phase and mechanical properties. A remarkable finding is that the diffusion zones not only enable the cooperative deformation between the brittle Ti-enriched zones and the ductile Nb-enriched zones but also act as the crack-arresters to prevent the local cracks in the Ti-enriched zones from further propagating across the composite.展开更多
Ti−Zr alloys(oxygen content 0.42−0.54 wt.%)were prepared via powder metallurgy and hot working.The results indicate that the Ti−Zr alloys exhibit Zr-rich and Zr-lean areas with the sameα-phase structure,and the Zr-ri...Ti−Zr alloys(oxygen content 0.42−0.54 wt.%)were prepared via powder metallurgy and hot working.The results indicate that the Ti−Zr alloys exhibit Zr-rich and Zr-lean areas with the sameα-phase structure,and the Zr-rich area shows a slightly higher oxygen content and a much finer grain size.The Ti−Zr alloys present a good combination of high strength(σs=700−900 MPa)and total elongation(>20%),and solid solution strengthening of oxygen plays a major role.Zr does not influence much the oxygen-induced brittleness due to its high structural similarity to Ti.Therefore,the high value of 0.54 wt.%is still within the critical oxygen content for the ductile-to-brittle transition of Ti and does not degrade the ductility.展开更多
To clarify the antibacterial behavior at early adhesion,two titania nanotube(TNT)arrays were fabricated on polished commercially pure titanium(Ti),and the interaction mechanisms between TNT arrays and the model bacter...To clarify the antibacterial behavior at early adhesion,two titania nanotube(TNT)arrays were fabricated on polished commercially pure titanium(Ti),and the interaction mechanisms between TNT arrays and the model bacteria(Escherichia coli,E.coli)were investigated.The results show that TNT arrays exhibit a significant early antibacterial effect,which is highly related to the surface free energy and nano-topography.The underlying antibacterial mechanisms include:(1)the anti-initial-attachment effect at the lag phase(0−4 h);(2)the anti-proliferation and physical bactericidal effects at the logarithmic phase(4−12 h);(3)the reduced antimicrobial properties probably due to the overgrowth of bacteria on TNT arrays at the stationary phase(12 h and then).展开更多
Hydroxyapatite（HA） and strontium（Sr） incorporated HA coatings with different Sr contents were prepared on Mg-4 Zn substrates by electrochemical deposition method. Fourier transform infrared（FTIR） spectroscopy, X...Hydroxyapatite（HA） and strontium（Sr） incorporated HA coatings with different Sr contents were prepared on Mg-4 Zn substrates by electrochemical deposition method. Fourier transform infrared（FTIR） spectroscopy, X-ray diffraction（XRD）, scanning electron microscopy（SEM）, energy dispersive spectroscopy（EDS） and electrochemical workstation were applied for the composition, phase constitution, morphology analyses and corrosion tests. The results reveal that the incorporation of Sr in coatings does not lead to dramatical change of functional groups and the crystal structure of the HA phase, but the crystal size and crystallinity decrease with increasing Sr content, which should be attributed to the lattice distortion and different occupancies of Sr and Ca ions. The 10 Sr HA@Mg-4 Zn samples show the lowest corrosion current density and the highest corrosion potential, and also exhibit the lowest amount of hydrogen evolution among all coated samples.展开更多
Investigations on manual laterality in non-human primates can help clarify human evolutionary origins of hand preference and cerebral cognition. Although body posture can influence primate hand preference, investigati...Investigations on manual laterality in non-human primates can help clarify human evolutionary origins of hand preference and cerebral cognition. Although body posture can influence primate hand preference, investigations on how posture affects hylobatid manual laterality are still in their infancy. This study focused on how spontaneous bipedal behavioral tasks affect hand preference in Hylobatidae. Ten captive northern white-cheeked gibbons (Nomascus leucogenys) were chosen as focal subjects. Unimanual grooming during sitting posture and supported bipedal posture were applied as behavioral tasks. The gibbons displayed a modest tendency on left-hand preference during sitting posture and right-hand preference during supported bipedal posture, although no group-level hand preference was detected for either posture. From the sitting to supported bipedal posture, 70% of individuals displayed different degrees of right-side deviation trends. The strength of manual laterality in the supported bipedal posture was higher than that in the sitting posture. We found significant sex differences in manual laterality during supported bipedal posture but not during sitting posture. Thus, to a certain degree, bipedal posture in N. leucogenys facilitates stronger hand preference, elicits a rightward trend in manual laterality, and produces sex-specific hand preference.展开更多
The inclusions evolution behavior in the continuous casting slab, rolled plates, and simulated welding samples of EH36 steels with and without Zr addition has been systematically investigated. The inclusions in plain ...The inclusions evolution behavior in the continuous casting slab, rolled plates, and simulated welding samples of EH36 steels with and without Zr addition has been systematically investigated. The inclusions in plain EH36 steel are almost composed of Al-Ca-S-O（-Mn） and undergo negligible changes during the whole process. With Zr addition, a large amount of individually fine MnS precipitates and Zr-containing inclusions are generated. In the rolled EH36-Zr sample, Zr-containing complex inclusions are effective to promote the nucleation of acicular ferrite on the surface, which are hardly found in the simulated welding sample of EH36-Zr steel due to the segregation of soluble Ti and Zr on the grain boundary.展开更多
One of the critical issues in the development of novel metallic biomaterials is the design and fabrication of metallic scaffolds and implants with hierarchical structures mimicking human bones. In this work, selective...One of the critical issues in the development of novel metallic biomaterials is the design and fabrication of metallic scaffolds and implants with hierarchical structures mimicking human bones. In this work, selective laser melting(SLM) and electrochemical anodization were applied to fabricate dense Ti-6 A1-4 V components with macro-micron-nanoscale hierarchical surfaces. Scanning electron microscopy(SEM), 3 D laser scanning microscopy(3 D LSM), contact angle video system, fluorescence microscopy and spectrophotometer were used to investigate the properties of the samples. The results reveal that the SLMed post-anodization(SLM-TNT) exhibits enhanced or at least comparable wettability, protein adsorption and biological response of mesenchymal stem cells(MSCs) in comparison with the three reference configurations, i.e., the polished Ti-6 Al-4 V(PO-Ti64), the SLMed Ti-6 A1-4 V(SLM-Ti64) and the polished Ti-6 A1-4 V post-anodization(PO-TNT). The improved cytocompatibility of the samples after SLM and anodization should be mainly attributed to the nanoscale tubular features,while the macro-micron-scale structures only lead to slight preference for cell attachment.展开更多
基金financially supported by the National Natural Science Foundation of China(No.52171114)the Innovation-oriented Advanced Technology and Industrial Technology Program Project of Hunan Province,China(No.2020SK2017)。
基金Project(51625404)supported by the National Natural Science Foundation for Distinguished Young Scholar of ChinaProjects(51604104,51504295)supported by the National Natural Science Foundation of China
文摘In order to investigate the real-time cracking behavior of each component of a composite with strong interfacial bonding among lamellae, Ti-18 Nb(at.%) composite was prepared by spark plasma sintering(SPS), followed by hot-rolling, annealing, and quenching. The microstructure and mechanical properties were characterized by scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS), micro-region X-ray diffractometry(MRXRD), nanoindentation, and in-situ scanning electron microscopy tensile testing. The results show that the Ti-18 Nb consists of Ti-enriched, diffusion and Nb-enriched zones, and the sharp Nb gradient across different zones leads to inhomogeneous distribution of phase and mechanical properties. A remarkable finding is that the diffusion zones not only enable the cooperative deformation between the brittle Ti-enriched zones and the ductile Nb-enriched zones but also act as the crack-arresters to prevent the local cracks in the Ti-enriched zones from further propagating across the composite.
基金Project(51625404)supported by the National Natural Science Foundation for Distinguished Young Scholar of China。
文摘Ti−Zr alloys(oxygen content 0.42−0.54 wt.%)were prepared via powder metallurgy and hot working.The results indicate that the Ti−Zr alloys exhibit Zr-rich and Zr-lean areas with the sameα-phase structure,and the Zr-rich area shows a slightly higher oxygen content and a much finer grain size.The Ti−Zr alloys present a good combination of high strength(σs=700−900 MPa)and total elongation(>20%),and solid solution strengthening of oxygen plays a major role.Zr does not influence much the oxygen-induced brittleness due to its high structural similarity to Ti.Therefore,the high value of 0.54 wt.%is still within the critical oxygen content for the ductile-to-brittle transition of Ti and does not degrade the ductility.
基金The authors are grateful for the financial supports from the National Natural Science Foundation of China(Nos.51604104,52171114,81702709)the Innovation-oriented Advanced Technology and Industrial Technology Program Project of Hunan Province,China(No.2020SK2017)+2 种基金the Central South University Postgraduate Education and Teaching Reform Project,China(No.2020JGB116)the Natural Science Foundation of Hunan Province,China(No.2020JJ4459)the Fundamental Research Funds for the Central Universities of Central South University,China(No.CX20200267).
文摘To clarify the antibacterial behavior at early adhesion,two titania nanotube(TNT)arrays were fabricated on polished commercially pure titanium(Ti),and the interaction mechanisms between TNT arrays and the model bacteria(Escherichia coli,E.coli)were investigated.The results show that TNT arrays exhibit a significant early antibacterial effect,which is highly related to the surface free energy and nano-topography.The underlying antibacterial mechanisms include:(1)the anti-initial-attachment effect at the lag phase(0−4 h);(2)the anti-proliferation and physical bactericidal effects at the logarithmic phase(4−12 h);(3)the reduced antimicrobial properties probably due to the overgrowth of bacteria on TNT arrays at the stationary phase(12 h and then).
基金Project(51604104) supported by the National Natural Science Foundation of ChinaProject(JCYJ20140417113430610) supported by the Development and Reform Commission of Shenzhen Municipality,China
文摘Hydroxyapatite（HA） and strontium（Sr） incorporated HA coatings with different Sr contents were prepared on Mg-4 Zn substrates by electrochemical deposition method. Fourier transform infrared（FTIR） spectroscopy, X-ray diffraction（XRD）, scanning electron microscopy（SEM）, energy dispersive spectroscopy（EDS） and electrochemical workstation were applied for the composition, phase constitution, morphology analyses and corrosion tests. The results reveal that the incorporation of Sr in coatings does not lead to dramatical change of functional groups and the crystal structure of the HA phase, but the crystal size and crystallinity decrease with increasing Sr content, which should be attributed to the lattice distortion and different occupancies of Sr and Ca ions. The 10 Sr HA@Mg-4 Zn samples show the lowest corrosion current density and the highest corrosion potential, and also exhibit the lowest amount of hydrogen evolution among all coated samples.
基金supported by the National Natural Science Foundation of China(31200293,31730104,31772468)
文摘Investigations on manual laterality in non-human primates can help clarify human evolutionary origins of hand preference and cerebral cognition. Although body posture can influence primate hand preference, investigations on how posture affects hylobatid manual laterality are still in their infancy. This study focused on how spontaneous bipedal behavioral tasks affect hand preference in Hylobatidae. Ten captive northern white-cheeked gibbons (Nomascus leucogenys) were chosen as focal subjects. Unimanual grooming during sitting posture and supported bipedal posture were applied as behavioral tasks. The gibbons displayed a modest tendency on left-hand preference during sitting posture and right-hand preference during supported bipedal posture, although no group-level hand preference was detected for either posture. From the sitting to supported bipedal posture, 70% of individuals displayed different degrees of right-side deviation trends. The strength of manual laterality in the supported bipedal posture was higher than that in the sitting posture. We found significant sex differences in manual laterality during supported bipedal posture but not during sitting posture. Thus, to a certain degree, bipedal posture in N. leucogenys facilitates stronger hand preference, elicits a rightward trend in manual laterality, and produces sex-specific hand preference.
文摘The inclusions evolution behavior in the continuous casting slab, rolled plates, and simulated welding samples of EH36 steels with and without Zr addition has been systematically investigated. The inclusions in plain EH36 steel are almost composed of Al-Ca-S-O（-Mn） and undergo negligible changes during the whole process. With Zr addition, a large amount of individually fine MnS precipitates and Zr-containing inclusions are generated. In the rolled EH36-Zr sample, Zr-containing complex inclusions are effective to promote the nucleation of acicular ferrite on the surface, which are hardly found in the simulated welding sample of EH36-Zr steel due to the segregation of soluble Ti and Zr on the grain boundary.
基金financially supported by the National Natural Science Foundation of China (No. 51604104)Shenzhen Science and Technology Innovation Commission (No. ZDSYS201703031748354)the National Science Foundation of Guangdong Province (No. 2016A030313756)
文摘One of the critical issues in the development of novel metallic biomaterials is the design and fabrication of metallic scaffolds and implants with hierarchical structures mimicking human bones. In this work, selective laser melting(SLM) and electrochemical anodization were applied to fabricate dense Ti-6 A1-4 V components with macro-micron-nanoscale hierarchical surfaces. Scanning electron microscopy(SEM), 3 D laser scanning microscopy(3 D LSM), contact angle video system, fluorescence microscopy and spectrophotometer were used to investigate the properties of the samples. The results reveal that the SLMed post-anodization(SLM-TNT) exhibits enhanced or at least comparable wettability, protein adsorption and biological response of mesenchymal stem cells(MSCs) in comparison with the three reference configurations, i.e., the polished Ti-6 Al-4 V(PO-Ti64), the SLMed Ti-6 A1-4 V(SLM-Ti64) and the polished Ti-6 A1-4 V post-anodization(PO-TNT). The improved cytocompatibility of the samples after SLM and anodization should be mainly attributed to the nanoscale tubular features,while the macro-micron-scale structures only lead to slight preference for cell attachment.
