A range of poly（ε-caprolactone）/poly（N-vinyl-2-pyrrolidone） amphiphilic block copolymers with well-defined hydrophilic chain length were synthesized by the living/controlled reversible addition fragmentation chai...A range of poly（ε-caprolactone）/poly（N-vinyl-2-pyrrolidone） amphiphilic block copolymers with well-defined hydrophilic chain length were synthesized by the living/controlled reversible addition fragmentation chain transfer polymerization method. The composition and struc- ture of the targeted resultants were characterized with 1H NMR, 13C NMR, FT-IR spec- troscopy and gel permeation chromatography. The various block copolymers were success- fully employed to fabricate the spherical micelle with core-shell morphological structure. The poly（N-vinyl-2-pyrrolidone） block-dependent characteristics of the copolymeric micelles were investigated by fluorescence spectroscopy, dynamic light scattering, and transmission electron microscopy. The solubilization of the hydrophobic ibuprofen as a model drug in the micelle solution was also explored. It was found that the drug loading contents are related to the micellar morphology structure determined by hydrophilic chain length in the copolymer.展开更多
Hardfill is a new type of artificially cemented material for dam construction works,with a wide application prospect.Its mechanical behavior lies between concrete and rockfill materials.A series of large-scale triaxia...Hardfill is a new type of artificially cemented material for dam construction works,with a wide application prospect.Its mechanical behavior lies between concrete and rockfill materials.A series of large-scale triaxial tests are performed on hardfill specimens at different ages,and the stress-strain behavior of hardfill is further discussed.The strength and stress-strain relationship of hardfill materials show both frictional mechanism and cohesive mechanism.An age-related constitutive model of hardfill is developed,which is a parallel model consisting of two components,rockfill component and cementation component.Moreover,a comparison is made between the simulated and the experimental results,which shows that the parallel model can reflect the mechanical characteristics of both rockfill-like nonlinearity and concrete-like age relativity.In addition,a simplified method for the determination of parameters is proposed.展开更多
The influence of ordered structure on the dislocation configuration,structure of anti-phase domain boundary,partial dislocation slips,etc.are analyzed in the background of promoting the plasticity of iron based ordere...The influence of ordered structure on the dislocation configuration,structure of anti-phase domain boundary,partial dislocation slips,etc.are analyzed in the background of promoting the plasticity of iron based ordered solid solutions with second-order phase transformation.The principles of deformation softening and annealing hardening in ordered solid solutions are discussed because of deformation induced structure disordering.It is concluded that the independent slip ability of the partial dislocations and the corresponding low temperature plasticity of ordered solid solutions could be promoted obviously by proper alloying effects,which reduces the anti-phase domain boundary energy,or by maintaining the disordering state into the low temperature range.The similar principles could be also used to modify the low temperature plasticity of other metal based ordered solid solutions.展开更多
文摘A range of poly（ε-caprolactone）/poly（N-vinyl-2-pyrrolidone） amphiphilic block copolymers with well-defined hydrophilic chain length were synthesized by the living/controlled reversible addition fragmentation chain transfer polymerization method. The composition and struc- ture of the targeted resultants were characterized with 1H NMR, 13C NMR, FT-IR spec- troscopy and gel permeation chromatography. The various block copolymers were success- fully employed to fabricate the spherical micelle with core-shell morphological structure. The poly（N-vinyl-2-pyrrolidone） block-dependent characteristics of the copolymeric micelles were investigated by fluorescence spectroscopy, dynamic light scattering, and transmission electron microscopy. The solubilization of the hydrophobic ibuprofen as a model drug in the micelle solution was also explored. It was found that the drug loading contents are related to the micellar morphology structure determined by hydrophilic chain length in the copolymer.
基金supported partially by the National Natural Science Foundation of China (Grant No. 10932012)the China-Europe Science and Technology Cooperation Program (Grant No. 0820)European Commission (Grant No. FP7-NMP-2007-LARGE-1)
文摘Hardfill is a new type of artificially cemented material for dam construction works,with a wide application prospect.Its mechanical behavior lies between concrete and rockfill materials.A series of large-scale triaxial tests are performed on hardfill specimens at different ages,and the stress-strain behavior of hardfill is further discussed.The strength and stress-strain relationship of hardfill materials show both frictional mechanism and cohesive mechanism.An age-related constitutive model of hardfill is developed,which is a parallel model consisting of two components,rockfill component and cementation component.Moreover,a comparison is made between the simulated and the experimental results,which shows that the parallel model can reflect the mechanical characteristics of both rockfill-like nonlinearity and concrete-like age relativity.In addition,a simplified method for the determination of parameters is proposed.
基金supported by the Independent Research Project of the State Key Laboratory for Advanced Metals and Materials (Grant No. 2010z-12)
文摘The influence of ordered structure on the dislocation configuration,structure of anti-phase domain boundary,partial dislocation slips,etc.are analyzed in the background of promoting the plasticity of iron based ordered solid solutions with second-order phase transformation.The principles of deformation softening and annealing hardening in ordered solid solutions are discussed because of deformation induced structure disordering.It is concluded that the independent slip ability of the partial dislocations and the corresponding low temperature plasticity of ordered solid solutions could be promoted obviously by proper alloying effects,which reduces the anti-phase domain boundary energy,or by maintaining the disordering state into the low temperature range.The similar principles could be also used to modify the low temperature plasticity of other metal based ordered solid solutions.
