本文评述了近年超塑性材料断裂研究理论进展。理论分析得出的一系列关系式可以反映这两个参数对塑性的贡献。其中 L-Z-B 关系式可以将经典理论和现代分析结合,描述了材料塑性和超塑性的基本规律。在众多限制超塑性变形能力的因素中,孔...本文评述了近年超塑性材料断裂研究理论进展。理论分析得出的一系列关系式可以反映这两个参数对塑性的贡献。其中 L-Z-B 关系式可以将经典理论和现代分析结合,描述了材料塑性和超塑性的基本规律。在众多限制超塑性变形能力的因素中,孔洞的影响可以通过综合了 m 值和孔洞长大速率两个参数(宏观参数和微观参数)的“超塑性断裂机构图”得以反映;当 m 值在变形中变化时,可以建立延伸率与最终 m 值之间的定量关系,这一关系又恰好与 G-A 的 m-ef 关系在形式上完全一致;各种缺陷(初始的或环境的)影响可以在理论分析中被反映,并且建立了它们之间的定量关系。展开更多
Background：Roughly focused extracorporeal shock waves therapy （ESWT） is characterized by a wide focal area,a large therapy zone,easy positioning,and less pain during treatment.The purpose of this study was to inves...Background：Roughly focused extracorporeal shock waves therapy （ESWT） is characterized by a wide focal area,a large therapy zone,easy positioning,and less pain during treatment.The purpose of this study was to investigate the effects of roughly focused ESWT on the expression of osteoprotegerin （OPG） and bone morphogenetic protein-2 （BMP-2） in osteoporotic fractures in rats.Methods：Seventy-two female Sprague-Dawley （SD） rats,3 months old,were divided into sham-operated group （n =6） and an ovariectomized （OVX） group （n =66）.Sixty OVX SD rats were used as a model of double proximal tibial osteotomy and inner fixation.The osteotomy site in the left tibia was treated with roughly focused ESWT once at an energy density of 0.26 mJ/mm^2,60 doses/min,and 2000 pact quantities.The contralateral right tibia was left untreated and served as a control.Expression of OPG and BMP-2 in the callus of the osteoporotic fracture area was assessed using immunohistochemistry,real-time polymerase chain reaction （PCR）,and Western blotting analysis.Results：Bone mineral density （BMD） at the proximal tibia,femur,and L5 spine was significantly reduced after ovariectomy.BMD of proximal tibia was 12.9% less in the OVX group than that in the sham-operated group.Meanwhile,bilateral oophorectomy resulted in a lower trabecular bone volume fraction （BV/TV） in the proximal tibia of the sham-OVX animals.Three months after bilateral oophorectomy,BV/TV was 14.29% of baseline BV/TV in OVX legs versus 45.91% in the sham-OVX legs （P 〈 0.001）.These data showed that the SD rats became a suitable model of osteoporosis,3 months after they were OVX.Immunohistochemical analysis showed higher levels of BMP-2 and OPG expression in the treatment group than those in the control group.Compared with the contralateral controls,decreased expression of OPG and BMP-2 at 3 days after roughly focused ESWT,followed by a later increase at 7 days,was indicated by real-time PCR and Western blotting analysis.The OPG messenger RNA （mRNA） expression levels peaked at 6 weeks after the shock wave treatment,paired with a much earlier （at 4 weeks） increase of BMP-2,and declined close to normal at 8 weeks.Conclusions：Roughly focused ESWT may promote the expression of OPG and BMP-2 in the osteoporotic fracture area in rats.BMP-2 and OPG may act synergistically and may lead to a significant enhancement of bone formation and remodeling.展开更多
文摘本文评述了近年超塑性材料断裂研究理论进展。理论分析得出的一系列关系式可以反映这两个参数对塑性的贡献。其中 L-Z-B 关系式可以将经典理论和现代分析结合,描述了材料塑性和超塑性的基本规律。在众多限制超塑性变形能力的因素中,孔洞的影响可以通过综合了 m 值和孔洞长大速率两个参数(宏观参数和微观参数)的“超塑性断裂机构图”得以反映;当 m 值在变形中变化时,可以建立延伸率与最终 m 值之间的定量关系,这一关系又恰好与 G-A 的 m-ef 关系在形式上完全一致;各种缺陷(初始的或环境的)影响可以在理论分析中被反映,并且建立了它们之间的定量关系。
基金This work was supported by grants from the National Nature Science Foundation of China （No. 81071501） and the Shanghai Committee of Science and Technology, China （No. 09411966500）.
文摘Background：Roughly focused extracorporeal shock waves therapy （ESWT） is characterized by a wide focal area,a large therapy zone,easy positioning,and less pain during treatment.The purpose of this study was to investigate the effects of roughly focused ESWT on the expression of osteoprotegerin （OPG） and bone morphogenetic protein-2 （BMP-2） in osteoporotic fractures in rats.Methods：Seventy-two female Sprague-Dawley （SD） rats,3 months old,were divided into sham-operated group （n =6） and an ovariectomized （OVX） group （n =66）.Sixty OVX SD rats were used as a model of double proximal tibial osteotomy and inner fixation.The osteotomy site in the left tibia was treated with roughly focused ESWT once at an energy density of 0.26 mJ/mm^2,60 doses/min,and 2000 pact quantities.The contralateral right tibia was left untreated and served as a control.Expression of OPG and BMP-2 in the callus of the osteoporotic fracture area was assessed using immunohistochemistry,real-time polymerase chain reaction （PCR）,and Western blotting analysis.Results：Bone mineral density （BMD） at the proximal tibia,femur,and L5 spine was significantly reduced after ovariectomy.BMD of proximal tibia was 12.9% less in the OVX group than that in the sham-operated group.Meanwhile,bilateral oophorectomy resulted in a lower trabecular bone volume fraction （BV/TV） in the proximal tibia of the sham-OVX animals.Three months after bilateral oophorectomy,BV/TV was 14.29% of baseline BV/TV in OVX legs versus 45.91% in the sham-OVX legs （P 〈 0.001）.These data showed that the SD rats became a suitable model of osteoporosis,3 months after they were OVX.Immunohistochemical analysis showed higher levels of BMP-2 and OPG expression in the treatment group than those in the control group.Compared with the contralateral controls,decreased expression of OPG and BMP-2 at 3 days after roughly focused ESWT,followed by a later increase at 7 days,was indicated by real-time PCR and Western blotting analysis.The OPG messenger RNA （mRNA） expression levels peaked at 6 weeks after the shock wave treatment,paired with a much earlier （at 4 weeks） increase of BMP-2,and declined close to normal at 8 weeks.Conclusions：Roughly focused ESWT may promote the expression of OPG and BMP-2 in the osteoporotic fracture area in rats.BMP-2 and OPG may act synergistically and may lead to a significant enhancement of bone formation and remodeling.
