The microstructure and mechanical properties of Mg94Zn2Y4 extruded alloy containing long-period stacking ordered structures were systematically investigated by SEM and TEM analyses. The results show that the 18R-LPSO ...The microstructure and mechanical properties of Mg94Zn2Y4 extruded alloy containing long-period stacking ordered structures were systematically investigated by SEM and TEM analyses. The results show that the 18R-LPSO structure and α-Mg phase are observed in cast Mg94Zn2Y4 alloy. After extrusion, the LPSO structures are delaminated and Mg-slices with width of 50-200 nm are generated. By ageing at 498 K for 36 h, the ageing peak is attained andβ′phase is precipitated. Due to this novel precipitation, the microhardness ofα-Mg matrix increases apparently from HV108.9 to HV129.7. While the microhardness for LPSO structure is stabilized at about HV145. TEM observations and SAED patterns indicate that the β′ phase has unique orientation relationships betweenα-Mg and LPSO structures, the direction in the close-packed planes ofβ′precipitates perpendicular to that ofα-Mg and LPSO structures. The ultimate tensile strength for the peak-aged alloy achieves 410.7 MPa and the significant strength originates from the coexistence ofβ′precipitates and 18R-LPSO structures.展开更多
Various ordered mesoporous carbons （OMCs） have been prepared by evaporation-induced trieonstituent co-assembly method. Their mesostructural stability under different carbon content, aging time and acidity were conve...Various ordered mesoporous carbons （OMCs） have been prepared by evaporation-induced trieonstituent co-assembly method. Their mesostructural stability under different carbon content, aging time and acidity were conveniently monitored by X-ray diffraction, transmission electron microscopy, and N2 sorption isotherms techniques. The results show mesostruetural stability of OMCs is enhanced as the carbon content increases from 36% to 46%, further increasing carbon content deteriorates the mesostructural stability. Increasing aging time from 0.5 h to 5.0 h make the mesostructural stability go through an optimum （2.0 h） and gradually reduce framework shrinkage of the OMCs. Highly OMCs can only be obtained in the acidity range of 0.2-1.2 mol/L HC1, when the acidity is near the isoelectrie point of silica, the resulting OMCs have the best mesostructure stability. Under the optimum condition, the carbon content of 46%, aging time of 2.0 h, and 0.2 mol/L HCl, the resulting OMCs have the best mesostrueture stability and the highest BET surface areas of 2281 m2/g.展开更多
The microstructure evolution and strengthening mechanisms of Mg-10Gd-1Er-1Zn-0.6Zr(wt.%) alloy were focused in the view of the size parameters and volume fraction(fp) of dual phases(long period stacking ordered(LPSO) ...The microstructure evolution and strengthening mechanisms of Mg-10Gd-1Er-1Zn-0.6Zr(wt.%) alloy were focused in the view of the size parameters and volume fraction(fp) of dual phases(long period stacking ordered(LPSO) structures and β’ precipitates).Results show that two types of LPSO phases with different morphologies formed,and the morphology and size of both LPSO phases varied with the solution conditions.However,the volume fraction decreased monotonously with increasing solution temperature,which in turn raised the volume fraction of β’ phase during aging.The alloy exhibited an ultimate tensile strength of 352 MPa,a yield strength of 271 MPa,and an elongation of 3.5% after solution treatment at 500℃ for 12 h and aging at 200℃ for 114 h.In contrast to the LPSO phase,the β’ phase seems to play a more important role in enhancing the yield strength,and consequently,a decreased fLPSO/fβ’,ratio results in an increased yield strength.展开更多
Highly ordered nanocomposite arrays of Rh6G-Au-AAO are formed by filling anodized aluminum oxide （AAO） with Rhodamine 6G （Rh6G） and gold nanoparticles. The optical properties of Rh6G-Au-AAO are studied by visible ...Highly ordered nanocomposite arrays of Rh6G-Au-AAO are formed by filling anodized aluminum oxide （AAO） with Rhodamine 6G （Rh6G） and gold nanoparticles. The optical properties of Rh6G-Au-AAO are studied by visible absorptive and fluorescent spectroscopy. Compared with the fluorescence spectra of Rh6G-Au in the solution environment, the fluo- rescence peak intensities of Rh6G-Au-AAO are significantly enhanced, the maximum enhancement rate is 5.5, and a constant blue shift of-12 nm of peak positions is presented. The effects come from the spatial confinement of AAO and the inhibition of the fluorescence quenching effect induced by gold nanoparticles. The results show that the nanocomposite structures of fluorescence molecules-metal nanoparticles-AAO have a considerable potential in engineering molecular assemblies and creating functional materials of superior properties for future nanoDhotonics.展开更多
In this study, we reported the design, fabrication, and characterization of well- ordered arrays of vertically-aligned, epitaxial NiSi2/Si heterostructures and single- crystalline NiSi2 nanowires on （001）Si substrat...In this study, we reported the design, fabrication, and characterization of well- ordered arrays of vertically-aligned, epitaxial NiSi2/Si heterostructures and single- crystalline NiSi2 nanowires on （001）Si substrates. The epitaxial NiSi2 with {111} facets was found to be the first and the only silicide phase formed inside the Si nanowires after annealing at a temperature as low as 300℃. Upon annealing at 500 ℃ for 4 h, the residual parts of Si nanowires were completely consumed and the NiSi2/Si heterostructured nanowires were transformed to fully silicided NiSi2 nanowires. XRD, TEM and SAED analyses indicated that all the NiSi2 nanowires were single crystalline and their axial orientations were parallel to the [001] direction. The obtained vertically-aligned NiSi2 nanowires, owing to their well-ordered arrangement, single-crystalline structure, and low effective work function, exhibit excellent field-emission properties with a very low turn-on field of 1.1 V/m. The surface wettability of the nanowires was found to switch from hydrophobic to hydrophilic after the formation of NiSi2 phase and the measured water contact angle decreased with increasing extent of Ni silicidation. The increased hydrophilicity can be explained by the Wenzel model. The obtained results present the exciting prospect that the new approach proposed here will provide the capability to fabricate other highly-ordered, vertically-aligned fully silicided nanowire arrays and may offer potential applications in constructing vertical silicide-based nanodevices.展开更多
The generation of toxic non-native protein conformers has emerged as a unifying thread among disorders such as Alzheimer＇s disease, Parkinson＇s disease, and amyotrophic lateral sclerosis. Atomic-level detail regardi...The generation of toxic non-native protein conformers has emerged as a unifying thread among disorders such as Alzheimer＇s disease, Parkinson＇s disease, and amyotrophic lateral sclerosis. Atomic-level detail regarding dynamical changes that facilitate protein aggre- gation, as well as the structural features of large-scale ordered aggregates and soluble non-native oligomers, would contribute signifi- cantly to current understanding of these complex phenomena and offer potential strategies for inhibiting formation of cytotoxic species. However, experimental limitations often preclude the acquisition of high-resolution structural and mechanistic information for aggregating systems. Computational methods, particularly those combine both aU-atom and coarse-grained simulations to cover a wide range of time and length scales, have thus emerged as crucial tools for investigating protein aggregation. Here we review the current state of computational methodology for the study of protein self-assembly, with a focus on the application of these methods toward understanding of protein aggregates in human neurodegenerative disorders.展开更多
基金Project (BK2010392) supported by the Natural Science Foundation of Jiangsu Province of ChinaProject (3212000502) supported by the Innovation Foundation of Southeast University,China
文摘The microstructure and mechanical properties of Mg94Zn2Y4 extruded alloy containing long-period stacking ordered structures were systematically investigated by SEM and TEM analyses. The results show that the 18R-LPSO structure and α-Mg phase are observed in cast Mg94Zn2Y4 alloy. After extrusion, the LPSO structures are delaminated and Mg-slices with width of 50-200 nm are generated. By ageing at 498 K for 36 h, the ageing peak is attained andβ′phase is precipitated. Due to this novel precipitation, the microhardness ofα-Mg matrix increases apparently from HV108.9 to HV129.7. While the microhardness for LPSO structure is stabilized at about HV145. TEM observations and SAED patterns indicate that the β′ phase has unique orientation relationships betweenα-Mg and LPSO structures, the direction in the close-packed planes ofβ′precipitates perpendicular to that ofα-Mg and LPSO structures. The ultimate tensile strength for the peak-aged alloy achieves 410.7 MPa and the significant strength originates from the coexistence ofβ′precipitates and 18R-LPSO structures.
基金This work was supported by the National Natural Science Foundation of China （No.20872135）.
文摘Various ordered mesoporous carbons （OMCs） have been prepared by evaporation-induced trieonstituent co-assembly method. Their mesostructural stability under different carbon content, aging time and acidity were conveniently monitored by X-ray diffraction, transmission electron microscopy, and N2 sorption isotherms techniques. The results show mesostruetural stability of OMCs is enhanced as the carbon content increases from 36% to 46%, further increasing carbon content deteriorates the mesostructural stability. Increasing aging time from 0.5 h to 5.0 h make the mesostructural stability go through an optimum （2.0 h） and gradually reduce framework shrinkage of the OMCs. Highly OMCs can only be obtained in the acidity range of 0.2-1.2 mol/L HC1, when the acidity is near the isoelectrie point of silica, the resulting OMCs have the best mesostructure stability. Under the optimum condition, the carbon content of 46%, aging time of 2.0 h, and 0.2 mol/L HCl, the resulting OMCs have the best mesostrueture stability and the highest BET surface areas of 2281 m2/g.
基金Project(2016YFB0301101)supported by the National Key Research and Development Program of ChinaProject(Z161100002116033)supported by Beijing Municipal Science and Technology Commission,China+1 种基金Project(KZ201810005005)supported by Key Science and Technology Program of Beijing Municipal Commission of Education,ChinaProject(2172013)supported by Beijing Natural Science Foundation,China
文摘The microstructure evolution and strengthening mechanisms of Mg-10Gd-1Er-1Zn-0.6Zr(wt.%) alloy were focused in the view of the size parameters and volume fraction(fp) of dual phases(long period stacking ordered(LPSO) structures and β’ precipitates).Results show that two types of LPSO phases with different morphologies formed,and the morphology and size of both LPSO phases varied with the solution conditions.However,the volume fraction decreased monotonously with increasing solution temperature,which in turn raised the volume fraction of β’ phase during aging.The alloy exhibited an ultimate tensile strength of 352 MPa,a yield strength of 271 MPa,and an elongation of 3.5% after solution treatment at 500℃ for 12 h and aging at 200℃ for 114 h.In contrast to the LPSO phase,the β’ phase seems to play a more important role in enhancing the yield strength,and consequently,a decreased fLPSO/fβ’,ratio results in an increased yield strength.
基金supported by the National Natural Science Foundation of China (No.60978020)the Key International S&T Cooperation Project (No.2005DFA10170)+3 种基金the National "973 Project" (No.2007CB307001)the National Natural Science Foundation of China (No.60408006)the Natural Science Fund of Tianjin (No.06TXTJJC13500)Program for Changjiang Scholars and Innovative Research Team in Nankai University, and the Cultivation Fund of the Key Scientific and Technical Innovation Project
文摘Highly ordered nanocomposite arrays of Rh6G-Au-AAO are formed by filling anodized aluminum oxide （AAO） with Rhodamine 6G （Rh6G） and gold nanoparticles. The optical properties of Rh6G-Au-AAO are studied by visible absorptive and fluorescent spectroscopy. Compared with the fluorescence spectra of Rh6G-Au in the solution environment, the fluo- rescence peak intensities of Rh6G-Au-AAO are significantly enhanced, the maximum enhancement rate is 5.5, and a constant blue shift of-12 nm of peak positions is presented. The effects come from the spatial confinement of AAO and the inhibition of the fluorescence quenching effect induced by gold nanoparticles. The results show that the nanocomposite structures of fluorescence molecules-metal nanoparticles-AAO have a considerable potential in engineering molecular assemblies and creating functional materials of superior properties for future nanoDhotonics.
文摘In this study, we reported the design, fabrication, and characterization of well- ordered arrays of vertically-aligned, epitaxial NiSi2/Si heterostructures and single- crystalline NiSi2 nanowires on （001）Si substrates. The epitaxial NiSi2 with {111} facets was found to be the first and the only silicide phase formed inside the Si nanowires after annealing at a temperature as low as 300℃. Upon annealing at 500 ℃ for 4 h, the residual parts of Si nanowires were completely consumed and the NiSi2/Si heterostructured nanowires were transformed to fully silicided NiSi2 nanowires. XRD, TEM and SAED analyses indicated that all the NiSi2 nanowires were single crystalline and their axial orientations were parallel to the [001] direction. The obtained vertically-aligned NiSi2 nanowires, owing to their well-ordered arrangement, single-crystalline structure, and low effective work function, exhibit excellent field-emission properties with a very low turn-on field of 1.1 V/m. The surface wettability of the nanowires was found to switch from hydrophobic to hydrophilic after the formation of NiSi2 phase and the measured water contact angle decreased with increasing extent of Ni silicidation. The increased hydrophilicity can be explained by the Wenzel model. The obtained results present the exciting prospect that the new approach proposed here will provide the capability to fabricate other highly-ordered, vertically-aligned fully silicided nanowire arrays and may offer potential applications in constructing vertical silicide-based nanodevices.
文摘The generation of toxic non-native protein conformers has emerged as a unifying thread among disorders such as Alzheimer＇s disease, Parkinson＇s disease, and amyotrophic lateral sclerosis. Atomic-level detail regarding dynamical changes that facilitate protein aggre- gation, as well as the structural features of large-scale ordered aggregates and soluble non-native oligomers, would contribute signifi- cantly to current understanding of these complex phenomena and offer potential strategies for inhibiting formation of cytotoxic species. However, experimental limitations often preclude the acquisition of high-resolution structural and mechanistic information for aggregating systems. Computational methods, particularly those combine both aU-atom and coarse-grained simulations to cover a wide range of time and length scales, have thus emerged as crucial tools for investigating protein aggregation. Here we review the current state of computational methodology for the study of protein self-assembly, with a focus on the application of these methods toward understanding of protein aggregates in human neurodegenerative disorders.
