At present,shield tunneling often needs to pass through a large number of bridge pile foundations.However,there are few studies on the influence of shield tunneling on adjacent pile foundations by combining with groun...At present,shield tunneling often needs to pass through a large number of bridge pile foundations.However,there are few studies on the influence of shield tunneling on adjacent pile foundations by combining with groundwater seepage.Based on Winkler model,the calculation equations of shield tunneling on vertical and horizontal displacement of adjacent bridge pile are derived.Meanwhile,full and part three-dimensional finite element models are established to analyze the trend of bridge pier settlement,ground surface settlement trough,vertical and horizontal displacement of the pile and pile stress under three calculation conditions,i.e.,not considering groundwater effect,considering stable groundwater effect and fluid-soil interaction.The results show that the calculated value is small when the effect of groundwater is not considered;the seepage velocity of the soil above the excavation face is faster than that of the surrounding soil under fluid-soil interaction,and after the shield passing,the groundwater on both sides shows a flow trend of“U”shape on the ground surface supplying to the upper part of the tunnel;the vertical displacement of the pile body is bounded by the horizontal position of the top of the tunnel,the upper pile body settles,and the lower pile body deforms upward.The horizontal displacement of pile body presents a continuous“S”shape distribution,causing stress concentration near the tunnel.The calculated results of fluid-soil interaction are in good agreement with the field measured data and accord with the actual situation.展开更多
Background Dipeptidyl peptidase-lV （DPP-4） inhibitors are now used to improve postprandial glycemic control in type 2 diabetes. However, their effects on hepatic glucose production （HGP） in obesity are not clear. ...Background Dipeptidyl peptidase-lV （DPP-4） inhibitors are now used to improve postprandial glycemic control in type 2 diabetes. However, their effects on hepatic glucose production （HGP） in obesity are not clear. This study was designed to test the hypothesis that gluconeogenesis and HGP can be modulated by DPP-4 inhibitors in obesity. Methods Sprague Dawley male rats were divided into four groups, each on a different diet： general rat chow, n=10 （G）; G＋sitagliptin, n=10; high fat chow （obesity）, n=10 （55% fat calories, HFO）; HFO＋sitagliptin, n=10. After 10 weeks, the rats were fasted overnight and glucose metabolism was determined using 3-3H-glucose and 14C-glycerol as tracers. Results Glycerol rate of appearance （P 〈0.00001）, plasma glycerol （P 〈0.05） and free fatty acid （FFA） （P 〈0.05） concentrations, and HGP （P 〈0.05） were decreased in HFO＋sitagliptin group compared with HFO group, but there was no significant difference between G and G＋sitagliptin groups （P 〉0.05）. Gluconeogenesis in HFO group was five times of that in G rats （P 〈0.01）, but was significantly declined in HFO＋sitagliptin group （P 〈0.0001）. Conclusions Gluconeogenesis and HGP were inhibited by sitagliptin in high fat-induced obese rats due to decreased glycerol availability, which was a result of reduced glycerol release from adipose tissues. The finding suggests that sitagliptin is potentially useful for controlling fasting glucose in obesity, thereby delaying or preventing the development of diabetes.展开更多
基金Project(52078060)supported by the National Natural Science Foundation of ChinaProject(2020JJ4606)supported by the National Science Foundation of Hunan Province,China+1 种基金Project(18A127)supported by the Key Foundation of Education Department of Hunan Province,ChinaProject(2018IC19)supported by the International Cooperation and Development Project of Double-First-Class Scientific Research in Changsha University of Science&Technology,China。
文摘At present,shield tunneling often needs to pass through a large number of bridge pile foundations.However,there are few studies on the influence of shield tunneling on adjacent pile foundations by combining with groundwater seepage.Based on Winkler model,the calculation equations of shield tunneling on vertical and horizontal displacement of adjacent bridge pile are derived.Meanwhile,full and part three-dimensional finite element models are established to analyze the trend of bridge pier settlement,ground surface settlement trough,vertical and horizontal displacement of the pile and pile stress under three calculation conditions,i.e.,not considering groundwater effect,considering stable groundwater effect and fluid-soil interaction.The results show that the calculated value is small when the effect of groundwater is not considered;the seepage velocity of the soil above the excavation face is faster than that of the surrounding soil under fluid-soil interaction,and after the shield passing,the groundwater on both sides shows a flow trend of“U”shape on the ground surface supplying to the upper part of the tunnel;the vertical displacement of the pile body is bounded by the horizontal position of the top of the tunnel,the upper pile body settles,and the lower pile body deforms upward.The horizontal displacement of pile body presents a continuous“S”shape distribution,causing stress concentration near the tunnel.The calculated results of fluid-soil interaction are in good agreement with the field measured data and accord with the actual situation.
文摘Background Dipeptidyl peptidase-lV （DPP-4） inhibitors are now used to improve postprandial glycemic control in type 2 diabetes. However, their effects on hepatic glucose production （HGP） in obesity are not clear. This study was designed to test the hypothesis that gluconeogenesis and HGP can be modulated by DPP-4 inhibitors in obesity. Methods Sprague Dawley male rats were divided into four groups, each on a different diet： general rat chow, n=10 （G）; G＋sitagliptin, n=10; high fat chow （obesity）, n=10 （55% fat calories, HFO）; HFO＋sitagliptin, n=10. After 10 weeks, the rats were fasted overnight and glucose metabolism was determined using 3-3H-glucose and 14C-glycerol as tracers. Results Glycerol rate of appearance （P 〈0.00001）, plasma glycerol （P 〈0.05） and free fatty acid （FFA） （P 〈0.05） concentrations, and HGP （P 〈0.05） were decreased in HFO＋sitagliptin group compared with HFO group, but there was no significant difference between G and G＋sitagliptin groups （P 〉0.05）. Gluconeogenesis in HFO group was five times of that in G rats （P 〈0.01）, but was significantly declined in HFO＋sitagliptin group （P 〈0.0001）. Conclusions Gluconeogenesis and HGP were inhibited by sitagliptin in high fat-induced obese rats due to decreased glycerol availability, which was a result of reduced glycerol release from adipose tissues. The finding suggests that sitagliptin is potentially useful for controlling fasting glucose in obesity, thereby delaying or preventing the development of diabetes.
