A new severe plastic deformation(SPD)technique for improvement of the metallurgical properties of the magnesium alloys is presented.In this process,a cyclic extrusion compression angular pressing(CECAP)process is foll...A new severe plastic deformation(SPD)technique for improvement of the metallurgical properties of the magnesium alloys is presented.In this process,a cyclic extrusion compression angular pressing(CECAP)process is followed by an extrusion step in the outlet playing the role of additional back pressure.Therefore,more uniform and enhanced mechanical properties are expected in comparison with equal channel angular pressing(ECAP).In order to evaluate the effectiveness and capabilities of this new method,an AM60 magnesium alloy was processed.Finite element results exhibited a significant increase in strain values as well as uniform strain distribution for the new method.In addition,~110%increase in compressive stress was observed in new method compared to the conventional ECAP.Experimental results revealed a noticeable increase in the hardness and strength of the specimens processed by the new technique as a result of the formation of finer grains and more homogeneous microstructure with good distribution of refinedβ-phase along the boundaries.It may be concluded that the new process is very promising for future magnesium alloy products.展开更多
The biomagnesium alloys have been considered to be one of the most potential biodegradable metal materials due to its good mechanical compatibility, biological compatibility, biological security and biodegradable char...The biomagnesium alloys have been considered to be one of the most potential biodegradable metal materials due to its good mechanical compatibility, biological compatibility, biological security and biodegradable characteristics. However, the two major problems of high degradation rates in physiological environment and low mechanical properties prevent the development of biomagnesium alloys. In the present work, the samples of Mg-Zn-Y-Nd alloy were prepared by cyclic extrusion compression （CEC） and equal channel angular pressing （ECAP）. The microstructures, mechanical properties of alloy and its corrosion behavior in simulated body fluid （SBF） were evaluated. The results reveal that Mg-Zn-Y-Nd alloy consists of equiaxial fine grain structure with the homogeneous distribution of micrometer size and nano-sized second phase, which was caused by the dynamic recrystallization during the ECAP and CEC. The corrosion resistance of alloy was improved. The tensile and corrosion resistance were improved, especially the processed alloy exhibit uniform corrosion performances and decreased corrosion rate. This will provide theoretical ground for Mg-Zn-Y-Nd alloy as vascular stent application.展开更多
This study used the radioimmunoassay method to observe 11 cases of prolapsed interver-tebral disc and to detect the change of cAMP and cGMP in the cerebrospinal fluid before and after fingerpressing manipulation in ac...This study used the radioimmunoassay method to observe 11 cases of prolapsed interver-tebral disc and to detect the change of cAMP and cGMP in the cerebrospinal fluid before and after fingerpressing manipulation in acupuncture point Weizhong (UB 40) and Chengshan (UB 57) in order to discussthe mechanism of analgesia of finger pressing manipulation. The results show the pain was relieved afterfinger pressing manipulation. cGMP of the cerebrospinal fluid increased from 0. 51±0. 19 to 0. 63±0. 13pm/ml, in average 32% higher than before the treatment (P<0. 05) . Since cAMP/cGMP decreased from30.52±26. 42 to 23.20 ± 16.91, this shows the analgesic mechanism of finger pressing manipulation mightbe due to the fact that the therapy excited the selectively endogenous analgesic system, caused the in-creased release of endorphin, and was accompanied by regulation ot cAMP and cGMP.展开更多
文摘A new severe plastic deformation(SPD)technique for improvement of the metallurgical properties of the magnesium alloys is presented.In this process,a cyclic extrusion compression angular pressing(CECAP)process is followed by an extrusion step in the outlet playing the role of additional back pressure.Therefore,more uniform and enhanced mechanical properties are expected in comparison with equal channel angular pressing(ECAP).In order to evaluate the effectiveness and capabilities of this new method,an AM60 magnesium alloy was processed.Finite element results exhibited a significant increase in strain values as well as uniform strain distribution for the new method.In addition,~110%increase in compressive stress was observed in new method compared to the conventional ECAP.Experimental results revealed a noticeable increase in the hardness and strength of the specimens processed by the new technique as a result of the formation of finer grains and more homogeneous microstructure with good distribution of refinedβ-phase along the boundaries.It may be concluded that the new process is very promising for future magnesium alloy products.
基金Acknowledgements The authors are grateful for the support by National Key Technology R＆D Program of China （Grant No. 2012BAI18B01） and the National Natural Science Foundation of China （Grant No. 51171174）.
文摘The biomagnesium alloys have been considered to be one of the most potential biodegradable metal materials due to its good mechanical compatibility, biological compatibility, biological security and biodegradable characteristics. However, the two major problems of high degradation rates in physiological environment and low mechanical properties prevent the development of biomagnesium alloys. In the present work, the samples of Mg-Zn-Y-Nd alloy were prepared by cyclic extrusion compression （CEC） and equal channel angular pressing （ECAP）. The microstructures, mechanical properties of alloy and its corrosion behavior in simulated body fluid （SBF） were evaluated. The results reveal that Mg-Zn-Y-Nd alloy consists of equiaxial fine grain structure with the homogeneous distribution of micrometer size and nano-sized second phase, which was caused by the dynamic recrystallization during the ECAP and CEC. The corrosion resistance of alloy was improved. The tensile and corrosion resistance were improved, especially the processed alloy exhibit uniform corrosion performances and decreased corrosion rate. This will provide theoretical ground for Mg-Zn-Y-Nd alloy as vascular stent application.
文摘This study used the radioimmunoassay method to observe 11 cases of prolapsed interver-tebral disc and to detect the change of cAMP and cGMP in the cerebrospinal fluid before and after fingerpressing manipulation in acupuncture point Weizhong (UB 40) and Chengshan (UB 57) in order to discussthe mechanism of analgesia of finger pressing manipulation. The results show the pain was relieved afterfinger pressing manipulation. cGMP of the cerebrospinal fluid increased from 0. 51±0. 19 to 0. 63±0. 13pm/ml, in average 32% higher than before the treatment (P<0. 05) . Since cAMP/cGMP decreased from30.52±26. 42 to 23.20 ± 16.91, this shows the analgesic mechanism of finger pressing manipulation mightbe due to the fact that the therapy excited the selectively endogenous analgesic system, caused the in-creased release of endorphin, and was accompanied by regulation ot cAMP and cGMP.
