Damaged articular cartilage has very limited capacity for spontaneous healing. Tissue engineering provides a new hope for functional cartilage repair. Creation of an appropriate cell carrier is one of the critical ste...Damaged articular cartilage has very limited capacity for spontaneous healing. Tissue engineering provides a new hope for functional cartilage repair. Creation of an appropriate cell carrier is one of the critical steps for successful tissue engineering. With the supposition that a biomimetic construct might promise to generate better effects, we developed a novel composite scaffold and investigated its potential for cartilage tissue engineering.展开更多
By using the advanced instrumentation of a Computer Controlled Scanning Electron Microscope (CCSEM), X-ray diffraction (XRD) and X-ray fluorescence (XRF), the ash composition and the mineral components of six typical ...By using the advanced instrumentation of a Computer Controlled Scanning Electron Microscope (CCSEM), X-ray diffraction (XRD) and X-ray fluorescence (XRF), the ash composition and the mineral components of six typical Huainan coals of different origins were studied. The transformation of mineral matter at high temperatures was tracked by XRD in reducing conditions. The quartz phase decreased sharply and the anorthite content tended to increase at first and then decreased with increasing temperatures. The formed mullite phase reached a maximum at 1250 ℃ but showed a tendency of slow decline when the temperature was over 1250 ℃ . The mullite formed in the heating process was the main reason of the high ash melting temperature of Huainan coals. Differences in peak intensity of mullite and anorthite reflected differences in phase concentration of the quenched slag fractions, which contributed to the differences in ash melting temperatures. The differences in the location of an amorphous hump maximum indicated differences of glass types which may affect ash melting temperatures. For Huainan coal samples with relatively high ash melting tempera- tures, the intensity of the diffraction lines for mullite under reducing condition is high while for the samples with rela- tively low ash melting temperature the intensity for anorthite is high.展开更多
Microstructures and mechanical properties of Nd : YAG laser welded transformation induced plasticity (TRIP) steel with tensile strength of 645 MPa were studied. Due to high cooling speed of laser welding, the weld ...Microstructures and mechanical properties of Nd : YAG laser welded transformation induced plasticity (TRIP) steel with tensile strength of 645 MPa were studied. Due to high cooling speed of laser welding, the weld metal mainly consists of martensite different from the base metal, which is composed of ferrite matrix with bainite and a little retained austenite. Therefore, the weld metal has maximum hardness at welded joint. The yield strength and tensile strength of welded specimens tested perpendicular to weld line were almost equal to those of the base metal. But the yield strength and tensile strength of welded specimens tested parallel with weld line were a little higher than those of the base metal. The formability of laser welded TRIP steel was decreased compared with that of the base metal.展开更多
Because powders are mostly non-isometric during the sintering process, copper powders were chosen to study the effects of four material transport mechanisms, including surface diffusion, grain-boundary diffusion, volu...Because powders are mostly non-isometric during the sintering process, copper powders were chosen to study the effects of four material transport mechanisms, including surface diffusion, grain-boundary diffusion, volume diffusion, and multi-couplings. These material transport mechanisms were studied with respect to sintering neck growth of a non-isometric biosphere during initial sintering. The evolution of the neck growth in the four transport mechanisms was simulated by Visual C++ as well based on the model of different particles. The results show that the increase of the sintering temperature, both the grain-boundary diffusion and volume diffusion play primary roles in neck growth, while surface diffusion gradually becomes the secondary mechanism. Both the sintered neck and the shrinkage of the two centers increase with increasing temperature by means of the coupling diffusion mechanism. The radius of the sintering neck decreased, and the shrinkage rate of the two centers increased with an increase of the diameter ratio of the two spheres.展开更多
基金This study was supported by a grant from Guangdong ProvincialScience &Technology Project, China (No. 2003A302102).
文摘Damaged articular cartilage has very limited capacity for spontaneous healing. Tissue engineering provides a new hope for functional cartilage repair. Creation of an appropriate cell carrier is one of the critical steps for successful tissue engineering. With the supposition that a biomimetic construct might promise to generate better effects, we developed a novel composite scaffold and investigated its potential for cartilage tissue engineering.
基金Projects 2003001 supported by the key project of Huainan city, & 2004kj125 by the Science Funding of Department of Education of Anhui Province
文摘By using the advanced instrumentation of a Computer Controlled Scanning Electron Microscope (CCSEM), X-ray diffraction (XRD) and X-ray fluorescence (XRF), the ash composition and the mineral components of six typical Huainan coals of different origins were studied. The transformation of mineral matter at high temperatures was tracked by XRD in reducing conditions. The quartz phase decreased sharply and the anorthite content tended to increase at first and then decreased with increasing temperatures. The formed mullite phase reached a maximum at 1250 ℃ but showed a tendency of slow decline when the temperature was over 1250 ℃ . The mullite formed in the heating process was the main reason of the high ash melting temperature of Huainan coals. Differences in peak intensity of mullite and anorthite reflected differences in phase concentration of the quenched slag fractions, which contributed to the differences in ash melting temperatures. The differences in the location of an amorphous hump maximum indicated differences of glass types which may affect ash melting temperatures. For Huainan coal samples with relatively high ash melting tempera- tures, the intensity of the diffraction lines for mullite under reducing condition is high while for the samples with rela- tively low ash melting temperature the intensity for anorthite is high.
文摘Microstructures and mechanical properties of Nd : YAG laser welded transformation induced plasticity (TRIP) steel with tensile strength of 645 MPa were studied. Due to high cooling speed of laser welding, the weld metal mainly consists of martensite different from the base metal, which is composed of ferrite matrix with bainite and a little retained austenite. Therefore, the weld metal has maximum hardness at welded joint. The yield strength and tensile strength of welded specimens tested perpendicular to weld line were almost equal to those of the base metal. But the yield strength and tensile strength of welded specimens tested parallel with weld line were a little higher than those of the base metal. The formability of laser welded TRIP steel was decreased compared with that of the base metal.
基金supported by the National Natural Science Foundation of China(No.50574075)New Century Excellent Talents in University(NCET-05-0873)Specialized Research Fund for the Doctoral Program of Higher Education(SRFDP20060700011 and 04JC22)
文摘Because powders are mostly non-isometric during the sintering process, copper powders were chosen to study the effects of four material transport mechanisms, including surface diffusion, grain-boundary diffusion, volume diffusion, and multi-couplings. These material transport mechanisms were studied with respect to sintering neck growth of a non-isometric biosphere during initial sintering. The evolution of the neck growth in the four transport mechanisms was simulated by Visual C++ as well based on the model of different particles. The results show that the increase of the sintering temperature, both the grain-boundary diffusion and volume diffusion play primary roles in neck growth, while surface diffusion gradually becomes the secondary mechanism. Both the sintered neck and the shrinkage of the two centers increase with increasing temperature by means of the coupling diffusion mechanism. The radius of the sintering neck decreased, and the shrinkage rate of the two centers increased with an increase of the diameter ratio of the two spheres.