Using an optical microscope and scanning electron microscope (SEM), the variation of eutectic Si morphology of Al-Si alloy in solution treatment was observed to study its influence on mechanical properties and fractur...Using an optical microscope and scanning electron microscope (SEM), the variation of eutectic Si morphology of Al-Si alloy in solution treatment was observed to study its influence on mechanical properties and fracture behavior. The results show that eutectic Si undergoes stubbing, necking, fragmentation, and growth in the initial stage (250 min); in the middle solution stage (250 to 400 min), the eutectic Si morphology has no significant change, only the degree of spheroidizing becomes higher; after 600 min, the growth of eutectic Si is a coarsening process controlled by diffusion and follows the Liftshitz-Slyozov-Wangner (LSW) model, and the eutectic Si morphology deteriorates due to the occurrence of facets and lap. Based on the quantitative measure and regression analysis, the eutectic Si morphology has a remarkable influence on mechanical properties and fracture behavior.展开更多
Objective： To evaluate the lumbar stability and the primary clinical results of unilateral facetectomy, transforaminal lumbar interbody fusion （TLIF） and unilateral pedicle screw fixation by X-Tube system. Methods...Objective： To evaluate the lumbar stability and the primary clinical results of unilateral facetectomy, transforaminal lumbar interbody fusion （TLIF） and unilateral pedicle screw fixation by X-Tube system. Methods： Five human lumbar cadaveric functional spine units（FSU） were obtained and graded facetectomy by 0, 1/4, 1/2, 3/4 and 4/4 were performed respectively on the left articular process of them. The stability of these 5 models was evaluated at flexion, extension, lateral bending and axial rotation. After a serial of biomechanical researches, 23 patients from June 2004 to March 2006 in our department underwent unilateral facetectomy, transforaminal lumbar interbody fusion （posterior lumbar interbody fusion） and unilateral pedicle screw instrumentation by X-Tube system. After general anaesthesia, with the guide of fluoroscopy and using X-Tube system, procedures of unilateral endoscopic facetectomy, spinal nerve root decompression, autologus spongy bone transplantation, one cage oblique insertion and unilateral pedicle screw instrumentation were performed. Results： There was no significant difference in flexion, extension, lateral bending and axial rotation of lumbar motion range after unilateral graded facetectomy. The stability of left/right axial direction was greatly affected when the range of graded facetectomy exceed 1/2. According to the Nakai criteria, for the 23 patients, the clinical result was excellent in 15 （65.2%）, good in 6 （26.1%） and fair in 2 （8.7%）. The fusion rate was 95.6% in excellent and good cases. Although partial absorption of bone grafts was observed in 1 case which might indicate a unsuccessful fusion, there was no loosing and replacement of instrument and no clinical symptoms occurred. Conclusion： The lumbar stability will be affected significantly when the range of graded facetectomy exceeds 1/2. Procedures of unilateral facetectomy, transforaminal lumbar interbody fusion and unilateral pedicle screw fixation is an optional strategy for microsurgical reconstruction, though the indications of the procedure should be carefully restricted.展开更多
The excellent energy storage performance of covalent sulfur-carbon material has gradually attracted great interest. However, in the electrochemical sodium storage process, the bond evolution mechanism remains an elusi...The excellent energy storage performance of covalent sulfur-carbon material has gradually attracted great interest. However, in the electrochemical sodium storage process, the bond evolution mechanism remains an elusive topic. Herein, we develop a one-step annealing strategy to achieve a high covalent sulfur-carbon bridged hybrid(HCSC)utilizing phenylphosphinic acid as the carbon-source/catalyst and sodium sulfate as the sulfur-precursor/salt template, in which the sulfur mainly exists in the forms of C–S–C and C–S–S–C. Notably, most of the bridge bonds are electrochemically cleaved when the cycling voltage is lower than0.6 V versus Na/Na+, leading to the appearance of two visible redox peaks in the following cyclic voltammogram(CV) tests.The in-situ and ex-situ characterizations demonstrate that S^2- is formed in the reduction process and the carbon skeleton is concomitantly and irreversibly isomerized. Thus, the cleaved sulfur and isomerized carbon could jointly contribute to the sodium storage in 0.01–3.0 V. In a Na-S battery system, the activated HCSC in cut off voltage window of 0.6–2.8 V achieves a high reversible capacity(770 mA h g^-1 at 300 mA g^-1). This insight reveals the charge storage mechanism of sulfur-carbon bridged hybrid and provides an improved enlightenment on the interfacial chemistry of electrode materials.展开更多
文摘Using an optical microscope and scanning electron microscope (SEM), the variation of eutectic Si morphology of Al-Si alloy in solution treatment was observed to study its influence on mechanical properties and fracture behavior. The results show that eutectic Si undergoes stubbing, necking, fragmentation, and growth in the initial stage (250 min); in the middle solution stage (250 to 400 min), the eutectic Si morphology has no significant change, only the degree of spheroidizing becomes higher; after 600 min, the growth of eutectic Si is a coarsening process controlled by diffusion and follows the Liftshitz-Slyozov-Wangner (LSW) model, and the eutectic Si morphology deteriorates due to the occurrence of facets and lap. Based on the quantitative measure and regression analysis, the eutectic Si morphology has a remarkable influence on mechanical properties and fracture behavior.
文摘Objective： To evaluate the lumbar stability and the primary clinical results of unilateral facetectomy, transforaminal lumbar interbody fusion （TLIF） and unilateral pedicle screw fixation by X-Tube system. Methods： Five human lumbar cadaveric functional spine units（FSU） were obtained and graded facetectomy by 0, 1/4, 1/2, 3/4 and 4/4 were performed respectively on the left articular process of them. The stability of these 5 models was evaluated at flexion, extension, lateral bending and axial rotation. After a serial of biomechanical researches, 23 patients from June 2004 to March 2006 in our department underwent unilateral facetectomy, transforaminal lumbar interbody fusion （posterior lumbar interbody fusion） and unilateral pedicle screw instrumentation by X-Tube system. After general anaesthesia, with the guide of fluoroscopy and using X-Tube system, procedures of unilateral endoscopic facetectomy, spinal nerve root decompression, autologus spongy bone transplantation, one cage oblique insertion and unilateral pedicle screw instrumentation were performed. Results： There was no significant difference in flexion, extension, lateral bending and axial rotation of lumbar motion range after unilateral graded facetectomy. The stability of left/right axial direction was greatly affected when the range of graded facetectomy exceed 1/2. According to the Nakai criteria, for the 23 patients, the clinical result was excellent in 15 （65.2%）, good in 6 （26.1%） and fair in 2 （8.7%）. The fusion rate was 95.6% in excellent and good cases. Although partial absorption of bone grafts was observed in 1 case which might indicate a unsuccessful fusion, there was no loosing and replacement of instrument and no clinical symptoms occurred. Conclusion： The lumbar stability will be affected significantly when the range of graded facetectomy exceeds 1/2. Procedures of unilateral facetectomy, transforaminal lumbar interbody fusion and unilateral pedicle screw fixation is an optional strategy for microsurgical reconstruction, though the indications of the procedure should be carefully restricted.
基金supported by the National Key Research and Development Program of China(2017YFB0102003 and2018YFB0104204)the National Natural Science Foundation of China(51622406,21673298 and 21473258)+2 种基金Young Elite Scientists Sponsorship Program By CAST(2017QNRC001)the Project of Innovation Driven Plan in Central South University(2017CX004 and 2018CX005)the Program for Innovative Team(in Science and Technology)in the University of Henan Province of China(17IRTSTHN003)
文摘The excellent energy storage performance of covalent sulfur-carbon material has gradually attracted great interest. However, in the electrochemical sodium storage process, the bond evolution mechanism remains an elusive topic. Herein, we develop a one-step annealing strategy to achieve a high covalent sulfur-carbon bridged hybrid(HCSC)utilizing phenylphosphinic acid as the carbon-source/catalyst and sodium sulfate as the sulfur-precursor/salt template, in which the sulfur mainly exists in the forms of C–S–C and C–S–S–C. Notably, most of the bridge bonds are electrochemically cleaved when the cycling voltage is lower than0.6 V versus Na/Na+, leading to the appearance of two visible redox peaks in the following cyclic voltammogram(CV) tests.The in-situ and ex-situ characterizations demonstrate that S^2- is formed in the reduction process and the carbon skeleton is concomitantly and irreversibly isomerized. Thus, the cleaved sulfur and isomerized carbon could jointly contribute to the sodium storage in 0.01–3.0 V. In a Na-S battery system, the activated HCSC in cut off voltage window of 0.6–2.8 V achieves a high reversible capacity(770 mA h g^-1 at 300 mA g^-1). This insight reveals the charge storage mechanism of sulfur-carbon bridged hybrid and provides an improved enlightenment on the interfacial chemistry of electrode materials.
