Considering the droplet coalescence, the motion of a group of dispersed droplets in W/O emulsion in a DC electric field is simulated. The simulation demonstrates the evolutions of droplet number, size as well as its d...Considering the droplet coalescence, the motion of a group of dispersed droplets in W/O emulsion in a DC electric field is simulated. The simulation demonstrates the evolutions of droplet number, size as well as its distribution,local concentration distribution and droplet size-velocity relation with the applied time of electric field. The simulated average droplet size is roughly consistent with the experimental value. The simulated variation of droplet number with time under several applied voltages shows that increasing voltage is more effective for raising the rate of droplet coalescence than extending exerting time. However, with the further raise of applied voltage, the improvement in droplet coalescence rate becomes less significant. The evolution of simulated droplet size–velocity relationship with time shows that the inter-droplet electric repulsion force is very strong due to larger electric charge on the droplet under higher applied voltage, so that the magnitude and the direction of droplet velocity become more random, which looks helpful to droplet coalescence.展开更多
Objective: To study the effect of CO2 pneumoperitoneum and the special 30 degree head-down tilt position on the venous hemodynamics in the lower extremity. Methods: Color doplex ultrasound was adopted to evaluate the ...Objective: To study the effect of CO2 pneumoperitoneum and the special 30 degree head-down tilt position on the venous hemodynamics in the lower extremity. Methods: Color doplex ultrasound was adopted to evaluate the diameter and blood flow velocity of the right femoral vein of 18 patients undergoing gynecologic laparoscopy under the same pressure of pneumoperitoneum of 12 mmHg. The diameter of femoral vein and the flow velocity were measured; the blood flow volume was calculated based on the equation of Q = vπr2 . Result: After establishment of pneumoperitoneum, the dilation of the femoral vein and the decrease in the velocity and volume can be observed (P < 0.05). And the 30 degree head-down position could increase the flow velocity and volume of the femoral vein and decrease the diameter of the vessel ( P < 0.05). At 30 minutes of the 30 degree head-down tilt position, the blood flow ameliorated compared with that in prone position after the establishment of pneumoperitoneum. After deflation of pneumoperitoneum, the femoral vein remained dilated( P < 0. 05). Conclusion: During laparoscopy, CO2 pneumoperitoneum may result in the dilation of the vein in lower extremity and retar dance of blood flow. The 30 degree Trendlenburg position can ameliorate the blood flow in the lower extremity. The deflation of the pneumoperitoneum cannot eliminate the effect of CO2 pneumoperitoneum on the lower extremity veins, which may predispose deep venous thrombosis after laparoscopy.展开更多
基金Supported by the Special Research Project of Fujian Province(JK2012027)the Natural Science Foundation of Fujian Province(2014J01201)
文摘Considering the droplet coalescence, the motion of a group of dispersed droplets in W/O emulsion in a DC electric field is simulated. The simulation demonstrates the evolutions of droplet number, size as well as its distribution,local concentration distribution and droplet size-velocity relation with the applied time of electric field. The simulated average droplet size is roughly consistent with the experimental value. The simulated variation of droplet number with time under several applied voltages shows that increasing voltage is more effective for raising the rate of droplet coalescence than extending exerting time. However, with the further raise of applied voltage, the improvement in droplet coalescence rate becomes less significant. The evolution of simulated droplet size–velocity relationship with time shows that the inter-droplet electric repulsion force is very strong due to larger electric charge on the droplet under higher applied voltage, so that the magnitude and the direction of droplet velocity become more random, which looks helpful to droplet coalescence.
文摘Objective: To study the effect of CO2 pneumoperitoneum and the special 30 degree head-down tilt position on the venous hemodynamics in the lower extremity. Methods: Color doplex ultrasound was adopted to evaluate the diameter and blood flow velocity of the right femoral vein of 18 patients undergoing gynecologic laparoscopy under the same pressure of pneumoperitoneum of 12 mmHg. The diameter of femoral vein and the flow velocity were measured; the blood flow volume was calculated based on the equation of Q = vπr2 . Result: After establishment of pneumoperitoneum, the dilation of the femoral vein and the decrease in the velocity and volume can be observed (P < 0.05). And the 30 degree head-down position could increase the flow velocity and volume of the femoral vein and decrease the diameter of the vessel ( P < 0.05). At 30 minutes of the 30 degree head-down tilt position, the blood flow ameliorated compared with that in prone position after the establishment of pneumoperitoneum. After deflation of pneumoperitoneum, the femoral vein remained dilated( P < 0. 05). Conclusion: During laparoscopy, CO2 pneumoperitoneum may result in the dilation of the vein in lower extremity and retar dance of blood flow. The 30 degree Trendlenburg position can ameliorate the blood flow in the lower extremity. The deflation of the pneumoperitoneum cannot eliminate the effect of CO2 pneumoperitoneum on the lower extremity veins, which may predispose deep venous thrombosis after laparoscopy.
