Obesity-induced type 2 diabetes is mainly due to excessive free fatty acids leading to insulin resistance.Increasing thermogenesis is regarded as an effective strategy for hypolipidemia and hypoglycemia.Ginsenoside is...Obesity-induced type 2 diabetes is mainly due to excessive free fatty acids leading to insulin resistance.Increasing thermogenesis is regarded as an effective strategy for hypolipidemia and hypoglycemia.Ginsenoside is a natural active component in Panax ginseng C.A.Meyer,and some of them enhance thermogenesis.However,there are few studies on the mechanism and target of ginsenosides enhancing thermogenesis.Using thermogenic protein uncoupling protein 1(UCP1)-luciferase reporter assay,we identifi ed ginsenoside F1 as a novel UCP1 activator in the ginsenosides library.Using pull down assay and inhibitor interference,we found F1 binds toβ3-adrenergic receptors(β3-AR)to enhance UCP1 expression via cAMP/PKA/CREB pathway.We also investigated the ability of F1 on energy metabolism in obesity-induced diabetic mice,including body weight,body composition and energy expenditure.The results of proteomics showed that F1 signifi cantly up-regulated thermogenesis proteins and lipolytic proteins,but down-regulated fatty acid synthesis proteins.Ginsenoside F1 increased thermogenesis and ameliorated insulin resistance specifi cally by promoting the browning of white adipose tissue in obese mice.Additionally,ginsenoside F1 improves norepinephrine-induced insulin resistance in adipocytes and hepatocytes,and shows a stronger mitochondria respiration ability than norepinephrine.These fi ndings suggest that ginsenoside F1 is a promising lead compound in the improvement of insulin resistance.展开更多
The stable range of operation for the centrifugal compressor significantly influences the dynamic,economic,and environment-friendly characteristics of power systems.A deep understand-ing of the characteristics of inst...The stable range of operation for the centrifugal compressor significantly influences the dynamic,economic,and environment-friendly characteristics of power systems.A deep understand-ing of the characteristics of instability evolution is necessary to improve the compressor stability.A centrifugal compressor equipped with a vaneless diffuser is experimentally investigated using high-response static-pressure measurements.The results obtained indicate that three typical rotational-speed ranges exist based on the different instability evolution characteristics,which reveals the var-ious impeller–diffuser matching behaviors over the entire speed range.At low-speed ranges((40%–75%)N_(max),N_(max)is the maximum rotational speed),the compressor exhibits stable,Rotating Insta-bility(RI),impeller stall(diffuser stall),and surge modes.The impeller stall mode is induced by RI and propagates downstream,resulting in the diffuser stall and compressor surge modes.In the medium-speed range((75%–85%)N_(max)),the compressor exhibits stable,diffuser stall,RI,and surge modes.In the high-speed range((85%–100%)N_(max)),the compressor exhibits stable,diffuser stall,and surge modes.The dominant instability position is shifted from the impeller to the diffuser as the rotational speed increases.Both the impeller and diffuser stall present an irregular sawtooth static-pressure wave and exhibit broadband frequency spectrum patterns.展开更多
The stability of the flow in the vaneless diffuser of a centrifugal compressor is studied with the linear theory. The characteristics of direct and adjoint perturbation modes are investigated,and the receptivity of th...The stability of the flow in the vaneless diffuser of a centrifugal compressor is studied with the linear theory. The characteristics of direct and adjoint perturbation modes are investigated,and the receptivity of the instability mode to momentum forcing or mass injection is identified based on the adjoint modes. Analysis shows that the perturbation with the largest amplitude is located at the outlet of the vaneless diffuser, while the highest-receptivity region is located in the middle of the vaneless diffuser along the radial direction. The large difference between the direct and adjoint modes indicates that the instability mechanism cannot be identified from a study of either eigenmode separately. Therefore, the structural sensitivity analysis is adopted to study the feedback of the instability mode. The structural sensitivity of the eigenvalue which is proportional to the perturbation pressure and velocity is used to explain the mechanism of flow control for the vaneless diffuser.展开更多
基金supported by the National Natural Science Foundation of China[31872674]the Jilin Talent Development Foundation Grant[20200301018RQ]the Fundamental Research Funds for the Central Universities[CGZH202206].
文摘Obesity-induced type 2 diabetes is mainly due to excessive free fatty acids leading to insulin resistance.Increasing thermogenesis is regarded as an effective strategy for hypolipidemia and hypoglycemia.Ginsenoside is a natural active component in Panax ginseng C.A.Meyer,and some of them enhance thermogenesis.However,there are few studies on the mechanism and target of ginsenosides enhancing thermogenesis.Using thermogenic protein uncoupling protein 1(UCP1)-luciferase reporter assay,we identifi ed ginsenoside F1 as a novel UCP1 activator in the ginsenosides library.Using pull down assay and inhibitor interference,we found F1 binds toβ3-adrenergic receptors(β3-AR)to enhance UCP1 expression via cAMP/PKA/CREB pathway.We also investigated the ability of F1 on energy metabolism in obesity-induced diabetic mice,including body weight,body composition and energy expenditure.The results of proteomics showed that F1 signifi cantly up-regulated thermogenesis proteins and lipolytic proteins,but down-regulated fatty acid synthesis proteins.Ginsenoside F1 increased thermogenesis and ameliorated insulin resistance specifi cally by promoting the browning of white adipose tissue in obese mice.Additionally,ginsenoside F1 improves norepinephrine-induced insulin resistance in adipocytes and hepatocytes,and shows a stronger mitochondria respiration ability than norepinephrine.These fi ndings suggest that ginsenoside F1 is a promising lead compound in the improvement of insulin resistance.
基金co-supported by the National Natural Science Foundation of China(Nos.51906006,51736001,52006217)the Beijing Institute of Technology Research Fund Program for Young Scholars,China.
文摘The stable range of operation for the centrifugal compressor significantly influences the dynamic,economic,and environment-friendly characteristics of power systems.A deep understand-ing of the characteristics of instability evolution is necessary to improve the compressor stability.A centrifugal compressor equipped with a vaneless diffuser is experimentally investigated using high-response static-pressure measurements.The results obtained indicate that three typical rotational-speed ranges exist based on the different instability evolution characteristics,which reveals the var-ious impeller–diffuser matching behaviors over the entire speed range.At low-speed ranges((40%–75%)N_(max),N_(max)is the maximum rotational speed),the compressor exhibits stable,Rotating Insta-bility(RI),impeller stall(diffuser stall),and surge modes.The impeller stall mode is induced by RI and propagates downstream,resulting in the diffuser stall and compressor surge modes.In the medium-speed range((75%–85%)N_(max)),the compressor exhibits stable,diffuser stall,RI,and surge modes.In the high-speed range((85%–100%)N_(max)),the compressor exhibits stable,diffuser stall,and surge modes.The dominant instability position is shifted from the impeller to the diffuser as the rotational speed increases.Both the impeller and diffuser stall present an irregular sawtooth static-pressure wave and exhibit broadband frequency spectrum patterns.
文摘The stability of the flow in the vaneless diffuser of a centrifugal compressor is studied with the linear theory. The characteristics of direct and adjoint perturbation modes are investigated,and the receptivity of the instability mode to momentum forcing or mass injection is identified based on the adjoint modes. Analysis shows that the perturbation with the largest amplitude is located at the outlet of the vaneless diffuser, while the highest-receptivity region is located in the middle of the vaneless diffuser along the radial direction. The large difference between the direct and adjoint modes indicates that the instability mechanism cannot be identified from a study of either eigenmode separately. Therefore, the structural sensitivity analysis is adopted to study the feedback of the instability mode. The structural sensitivity of the eigenvalue which is proportional to the perturbation pressure and velocity is used to explain the mechanism of flow control for the vaneless diffuser.
