In order to prolong the service life of aircraft skin made from AA2524, the effects of laser shock peening(LSP) on fatigue crack growth(FCG) rate and fracture toughness(K_(c)) of AA2524 were investigated. Multiple LSP...In order to prolong the service life of aircraft skin made from AA2524, the effects of laser shock peening(LSP) on fatigue crack growth(FCG) rate and fracture toughness(K_(c)) of AA2524 were investigated. Multiple LSP treatment was performed on compact tension(CT) specimen from single side and double sides. The surface integrity was measured with Vickers hardness tester, X-ray diffractometer and confocal laser scanning microscope, respectively. FCG rate test and fracture toughness test under plane stress were carried out after LSP treatment. The microstructure features of cross-sections were observed with scanning electron microscope. The results showed that the micro-hardness and residual stress of CT specimens were increased dramatically after LSP treatment. Compared to the base metal(BM), the fatigue life was prolonged by 2.4 times and fracture toughness was increased by 22% after multiple LSP.展开更多
Glutathione （GSH） is the principal non-protein thiol responsible for maintaining intracellular redox status and protecting cells against oxidative/ nitrosative stresses. In the biological system, some GSH is bound t...Glutathione （GSH） is the principal non-protein thiol responsible for maintaining intracellular redox status and protecting cells against oxidative/ nitrosative stresses. In the biological system, some GSH is bound to proteins, and others exist freely, including the reduced glutathione and oxidized glutathione （GSSG）. Generally it is in a steady redox state for GSH/GSSG couple to participate in a variety of physiological functions. Earlier studies showed that chemically induced oxidative stress in vivo in rats resulted in increased GSSG and decreased GSH/GSSG ratio. The impairment of the glutathione homeostasis represents an indicator of tissue oxidative stresss status in human subjects.展开更多
Background Pomegranate （punica granatum） belongs to the family Punicaceae, and its peel has been used as a traditional Chinese medicine because of its efficacy in restraining intestine, promoting hemostasis, and kil...Background Pomegranate （punica granatum） belongs to the family Punicaceae, and its peel has been used as a traditional Chinese medicine because of its efficacy in restraining intestine, promoting hemostasis, and killing parasites. Pomegranate peel has been reported to possess wound-healing properties which are mainly attributed to its polyphenol extracts. The purpose of this study was to investigate the effect of pomegranate peel polyphenols （PPP） gel on cutaneous wound healing in diabetic rats. Methods AIIoxan-induced diabetic rats were given incisional wounds on each side of the mid-back and then treated daily with PPP gel （polyphenol mass fraction =30%） post-wounding. Rats were sacrificed on days 4, 7, 14, and 21 post-wounding to assess the rates of wound closure, histological characteristics; and to detect the contents of hydroxyproline, production of nitric oxide （NO）, and activities of NO synthase （NOS）, as well as the expressions of transforming growth factor-β1 （TGF-β1）, vascular endothelial growth factor （VEGF）, and epidermal growth factor （EGF） in wound tissue. Results Wound closure was significantly shortened when PPP gel was applied to the wounds of diabetic rats. Histological examination showed the ability of PPP gel to increase fibroblast infiltration, collagen regeneration, vascularization, and epithelialization in the wound area of diabetic rats. In addition, PPP gel-treated diabetic rats showed increased contents of hydroxyproline, production of NO, and activities of NOS and increased expressions of TGF-β1, VEGF, and EGF in wound tissues. Conclusion PPP gel may be a beneficial method for treating wound disorders associated with diabetes.展开更多
基金Project(52075552) supported by the National Natural Science Foundation of ChinaProject(kq2007085) supported by Changsha Municipal Natural Science Foundation,China。
文摘In order to prolong the service life of aircraft skin made from AA2524, the effects of laser shock peening(LSP) on fatigue crack growth(FCG) rate and fracture toughness(K_(c)) of AA2524 were investigated. Multiple LSP treatment was performed on compact tension(CT) specimen from single side and double sides. The surface integrity was measured with Vickers hardness tester, X-ray diffractometer and confocal laser scanning microscope, respectively. FCG rate test and fracture toughness test under plane stress were carried out after LSP treatment. The microstructure features of cross-sections were observed with scanning electron microscope. The results showed that the micro-hardness and residual stress of CT specimens were increased dramatically after LSP treatment. Compared to the base metal(BM), the fatigue life was prolonged by 2.4 times and fracture toughness was increased by 22% after multiple LSP.
文摘Glutathione （GSH） is the principal non-protein thiol responsible for maintaining intracellular redox status and protecting cells against oxidative/ nitrosative stresses. In the biological system, some GSH is bound to proteins, and others exist freely, including the reduced glutathione and oxidized glutathione （GSSG）. Generally it is in a steady redox state for GSH/GSSG couple to participate in a variety of physiological functions. Earlier studies showed that chemically induced oxidative stress in vivo in rats resulted in increased GSSG and decreased GSH/GSSG ratio. The impairment of the glutathione homeostasis represents an indicator of tissue oxidative stresss status in human subjects.
基金This work was supported by a grant from the National Natural Science Foundation of China （No. 30960527）.
文摘Background Pomegranate （punica granatum） belongs to the family Punicaceae, and its peel has been used as a traditional Chinese medicine because of its efficacy in restraining intestine, promoting hemostasis, and killing parasites. Pomegranate peel has been reported to possess wound-healing properties which are mainly attributed to its polyphenol extracts. The purpose of this study was to investigate the effect of pomegranate peel polyphenols （PPP） gel on cutaneous wound healing in diabetic rats. Methods AIIoxan-induced diabetic rats were given incisional wounds on each side of the mid-back and then treated daily with PPP gel （polyphenol mass fraction =30%） post-wounding. Rats were sacrificed on days 4, 7, 14, and 21 post-wounding to assess the rates of wound closure, histological characteristics; and to detect the contents of hydroxyproline, production of nitric oxide （NO）, and activities of NO synthase （NOS）, as well as the expressions of transforming growth factor-β1 （TGF-β1）, vascular endothelial growth factor （VEGF）, and epidermal growth factor （EGF） in wound tissue. Results Wound closure was significantly shortened when PPP gel was applied to the wounds of diabetic rats. Histological examination showed the ability of PPP gel to increase fibroblast infiltration, collagen regeneration, vascularization, and epithelialization in the wound area of diabetic rats. In addition, PPP gel-treated diabetic rats showed increased contents of hydroxyproline, production of NO, and activities of NOS and increased expressions of TGF-β1, VEGF, and EGF in wound tissues. Conclusion PPP gel may be a beneficial method for treating wound disorders associated with diabetes.
