The characteristics of the flowfields of a synthetic jet actuator are experimentally investigated with the slot-nozzle driven by the piezoelectric membrane. The particle image velocimetry （PIV） and the hot-wire anem...The characteristics of the flowfields of a synthetic jet actuator are experimentally investigated with the slot-nozzle driven by the piezoelectric membrane. The particle image velocimetry （PIV） and the hot-wire anemometer are utilized to measure the flowfields and the velocity profiles of the actuator with different actuating factors. Analytical results show that pairs of counter-rotating vortices are generated near the nozzle. With the development of the synthetic ject, the synthetic jet rapidly spreads in the slot-width direction; while in the slot-length direction, it contracts firstly and slowly spreads. The centerline velocity distribution has a up-down tendency varying with axial distances, and accelerates to its maximum at z/b= 10. The transverse velocity profile across the slot-width is centro-symmetric and self-similar. However, the velocity profiles across the slot-length are saddle-like near the nozzle. It shows that there are two resonance frequencies for the actuator. If the actuator works with the resonance frequency, the vorticity and the velocity of the synthetic jet are higher than those of other frequencies. Compared with the continuous jet, the synthetic jet shows special flow characteristics.展开更多
Background Our previous study showed that the combined Chinese herbs containing scutellaria baicalensis georgi and gardenia jasminoids ellis inhibited atherosclerosis. In this study, we sought to determine if baicalin...Background Our previous study showed that the combined Chinese herbs containing scutellaria baicalensis georgi and gardenia jasminoids ellis inhibited atherosclerosis. In this study, we sought to determine if baicalin and geniposide could inhibit atherosclerosis through Wntl and dickkopf-related protein-1 （DKK1）. Methods The wild-type and ApoE-/- mice were treated with baicalin, geniposide, and baicalin plus geniposide daily by gavage for 12 weeks. Blood lipid levels were measured with an automatic biochemistry analyzer. Aortic atherosclerotic lesion areas were analyzed with Image-ProPlus software. The mRNA and protein expression of DKK1, Wntt and nuclear factor-r,B （NF-κB） were measured with RT-PCR and Westem Blot. Serum levels of interleukin-12 （IL-12） were quantified with ELISA. Results The baicalin or geniposide monotherapy as well as combination therapy inhibited the development of atherosclerotic lesions, increased Wntl and decreased DKKI expression and elevated the ratio of Wntl/DKK1 compared with high-lipid diet group. However, only baicalin or geniposide monotherapy decreased NF-κB expression. Moreover, baicalin and geniposide monoor combination therapy lowered IL-12 levels. Geniposide reduced both serum total cholesterol and low density lipoprotein levels, while baicalin either alone or in combination with geniposide did not affect serum lipid levels. In human, umbilical vein endothelial ceils stimulated by oxidized low density lipoprotein, baicalin and geniposide also increased Wntl and decreased DKK1 expression and elevated the ratio of Wntl/DKK1. Condusions Baicalin and geniposide exert inflammation-regulatory effects and may prevent atherosclerotic lesions through enhancing Wntl and inhibit- ing DKK1 expression.展开更多
文摘The characteristics of the flowfields of a synthetic jet actuator are experimentally investigated with the slot-nozzle driven by the piezoelectric membrane. The particle image velocimetry （PIV） and the hot-wire anemometer are utilized to measure the flowfields and the velocity profiles of the actuator with different actuating factors. Analytical results show that pairs of counter-rotating vortices are generated near the nozzle. With the development of the synthetic ject, the synthetic jet rapidly spreads in the slot-width direction; while in the slot-length direction, it contracts firstly and slowly spreads. The centerline velocity distribution has a up-down tendency varying with axial distances, and accelerates to its maximum at z/b= 10. The transverse velocity profile across the slot-width is centro-symmetric and self-similar. However, the velocity profiles across the slot-length are saddle-like near the nozzle. It shows that there are two resonance frequencies for the actuator. If the actuator works with the resonance frequency, the vorticity and the velocity of the synthetic jet are higher than those of other frequencies. Compared with the continuous jet, the synthetic jet shows special flow characteristics.
基金This study was funded by grants from the Natural Science Foundation of Hubei Province in China （2012FFB02508）.
文摘Background Our previous study showed that the combined Chinese herbs containing scutellaria baicalensis georgi and gardenia jasminoids ellis inhibited atherosclerosis. In this study, we sought to determine if baicalin and geniposide could inhibit atherosclerosis through Wntl and dickkopf-related protein-1 （DKK1）. Methods The wild-type and ApoE-/- mice were treated with baicalin, geniposide, and baicalin plus geniposide daily by gavage for 12 weeks. Blood lipid levels were measured with an automatic biochemistry analyzer. Aortic atherosclerotic lesion areas were analyzed with Image-ProPlus software. The mRNA and protein expression of DKK1, Wntt and nuclear factor-r,B （NF-κB） were measured with RT-PCR and Westem Blot. Serum levels of interleukin-12 （IL-12） were quantified with ELISA. Results The baicalin or geniposide monotherapy as well as combination therapy inhibited the development of atherosclerotic lesions, increased Wntl and decreased DKKI expression and elevated the ratio of Wntl/DKK1 compared with high-lipid diet group. However, only baicalin or geniposide monotherapy decreased NF-κB expression. Moreover, baicalin and geniposide monoor combination therapy lowered IL-12 levels. Geniposide reduced both serum total cholesterol and low density lipoprotein levels, while baicalin either alone or in combination with geniposide did not affect serum lipid levels. In human, umbilical vein endothelial ceils stimulated by oxidized low density lipoprotein, baicalin and geniposide also increased Wntl and decreased DKK1 expression and elevated the ratio of Wntl/DKK1. Condusions Baicalin and geniposide exert inflammation-regulatory effects and may prevent atherosclerotic lesions through enhancing Wntl and inhibit- ing DKK1 expression.
